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Sample records for source ho ni

  1. Reentrant superconductivity in HoNi5-NbN-HoNi5 nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Gyanendra; Joshi, P. C.; Hossain, Z.; Budhani, R. C.

    2013-08-01

    Superconductivity (S) and ferromagnetism (F) are probed through transport and magnetization measurements in nanometer scale HoNi5-NbN (F-S) bilayers and HoNi5-NbN-HoNi5 (F-S-F) trilayers. The choice of materials has been made on the basis of their comparable ordering temperatures and strong magnetic anisotropy in HoNi5. We observe the normal state reentrant behavior in resistance vs. temperature plots of the F-S-F structures just below the superconducting transition in the limited range of HoNi5 layer thickness dHN (20\\ \\text{nm}) when d_{\\textit{NbN}} is fixed at{}\\simeq 10\\ \\text{nm} . The reentrance is quenched by increasing the out-of-plane (H_{\\perp} ) magnetic field and transport current where as in-plane (H_{\\parallel} ) field of \\leq 1500\\ \\text{Oe} has no effect on the reentrance. The origin of the reentrant behavior seen here in the range T_{\\textit{Curie}}/T_C \\leq 0.92 is attributed to a delicate balance between the magnetic exchange energy and the condensation energy in the interfacial regions of the trilayer.

  2. Enhanced ferromagnetic properties in Ho and Ni co-doped BiFeO3 ceramics

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    The magnetic properties of polycrystalline Bi1-xHoxFe1-yNiyO3 (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 Bi0.9Ho0.1Fe0.97Ni0.03O3 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, Bi0.9Ho0.1Fe0.97Ni0.03O3 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.

  3. Superconductivity and magnetism in (Ho xY 1- x)Ni 2B 2C

    NASA Astrophysics Data System (ADS)

    Eversmann, K.; Handstein, A.; Fuchs, G.; Cao, L.; Müller, K.-H.

    1996-02-01

    Superconducting and magnetic properties of polycrystalline samples of the pseudoquarternary system (Ho xY 1- x)Ni 2B 2C have been investigated by resistance and susceptibility measurements. A linear depression of the superconducting transition temperature with increasing magnetic ordering temperatures was found by variation of the Ho content providing evidence for magnetic pair breaking. This behaviour is analogous to the known scaling with the de Gennes factor of the rare earth elements in the family of quaternary RNi 2B 2C compounds. Both cases are described by a common scaling behaviour including the superconducting and magnetic transition temperatures. A reetrrant behaviour observed for Ho contents x>0.5 results in maximum in the temperature dependence of the upper critical field Hc2( T). These results are compared with Hc2( T) data of the RNi 2B 2C family ( R=Tm,Er).

  4. 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.

  5. Effect of Crystal Fields in Ho1 - xDyxNi2B2 C

    NASA Astrophysics Data System (ADS)

    Lee, W. C.

    2013-03-01

    From the anisotropy and the temperature dependence of magnetic susceptibilities of Ho1 - x Dyx Ni2B2 C system with magnetic field H perpendicular or parallel to c-axis, the crystalline electric field (CEF) effect has been studied and the magnetic exchange interaction constant Jex of rare-earth ions perpendicular to the c-axis estimated for 0 <=x <=1. The crystalline electric field parameter, B02, the first Steven parameter and the most dominant term in this system, are determined from the high-temperature-limit anisotropic Weiss temperatures of the magnetic susceptibilities and there is a broad minimum around x ~ 0.3, where superconducting transition temperature, TC, and Néel temperature, TN, are almost same.

  6. 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.

  7. High-field magnetic properties of Ho 2Fe 15M 2 compounds (M  Al, Ga, Ni and Si)

    NASA Astrophysics Data System (ADS)

    Wang, J. L.; Tang, N.; Li, W. Z.; Qin, W. D.; Pan, H. Y.; Nasunjilegal, B.; Yang, F. M.; de Boer, F. R.

    1996-07-01

    The crystalline structure and magnetic properties of the Ho 2Fe 15M 2 compounds with M  Al, Si, Ni, and Ga have been investigated. X-ray diffraction patterns on powder samples show that all compounds crystallize in the Th 2Ni 17-type structure. The substitution of Al and Ga for Fe leads to an increase in the lattice constants a and c, but a decrease for Si substitution. Substitution of all the M elements for Fe leads to an increase in the Curie temperature and to a decrease in the saturation magnetization. The exchange coupling constants JHoT between Ho and transition metal spins are found to be almost independent of the substituting atom.

  8. Microscopic changes in HoNi2B2C due to thermal treatment and its effect on superconductivity

    NASA Astrophysics Data System (ADS)

    Dertinger, A.; Dinnebier, R. E.; Kreyssig, A.; Stephens, P. W.; Pagola, S.; Loewenhaupt, M.; van Smaalen, S.; Braun, H. F.

    2001-05-01

    The low-temperature properties of HoNi2B2C strongly depend on its thermodynamic state established via thermal treatment. We present high resolution x-ray powder diffraction data taken on a pair of polycrystalline samples with identical chemical composition (HoNi2B2.1C) but annealed at different temperatures, namely, at 800 and at 1100 °C. Their superconducting transition temperatures differ by more than 10%. Rietveld refinement and difference Fourier analysis reveal subtle differences in the atomic parameters and in the electron density on the carbon site. Furthermore, a new atomic site can be identified for both samples, which is partially occupied with the lighter atoms boron or carbon.

  9. Electric and magnetic properties of Al86Ni8R6 (R=Sm, Gd, Ho) alloys in liquid and amorphous states

    NASA Astrophysics Data System (ADS)

    Sidorov, V.; Svec, P.; Svec, P.; Janickovic, D.; Mikhailov, V.; Sidorova, E.; Son, L.

    2016-06-01

    Electrical resistivity and magnetic susceptibility of Al86Ni8Sm6, Al86Ni8Gd6 and Al86Ni8Ho6 alloys are studied in a wide temperature range including amorphous, crystalline and liquid states. The negative value of resistivity temperature coefficient in amorphous ribbons is explained by the structural separation starting much before the beginning of their crystallization. The effective magnetic moments per Gd and Ho atoms are found to be essentially lower than for R3+ ions. The results are discussed in supposition of directed bonds between rare earth and aluminum atoms.

  10. Complex Structures in the Reentrant Phase Diagram of HoNi_2B_2C

    NASA Astrophysics Data System (ADS)

    Childers, J.; Zhang, J.; Olinger, A., Jr.; Metlushko, V.; Delong, L.; Canfield, P.

    1996-03-01

    HoNi_2B_2C exhibits a resistive onset to superconductivity near 9.0 K, followed by transitions to incommensurate magnetic order (IMO) at 6.0 K and 5.5 K, and commensurate antiferromagnetic order (AFM) at TN = 5.2 K. Vibrating reed (VR) and resistance data reveal two previously unobserved lines of magnetic anomalies in both the upper superconducting (SC) and lower reentrant SC regions for H || a*b*. The wide region between the upper onset of SC and the first magnetic anomaly reflects weak vortex pinning, possibly due to a subtle buildup of IMO from well above 8K. The interplay between SC and magnetic order is evident in abrupt displacements of transition lines to IMO near their crossing with the reentrant normal transition line for 5.2

  11. Angular dependence of metamagnetic transitions in HoNi{sub 2}B{sub 2}C

    SciTech Connect

    Canfield, P.C.; Budko, S.L.; Cho, B.K.; Lacerda, A.; Farrell, D.; Johnston-Halperin, E.; Kalatsky, V.A.; Pokrovsky, V.L.

    1997-01-01

    Detailed measurements of M(2 K, H, {theta}) of HoNi{sub 2}B{sub 2}C, where {theta} is the angle that the applied field H makes with the [110] axis while remaining perpendicular to the crystallographic c axis, reveal three metamagnetic transitions with angular dependences H{sub c1}=(4.1{plus_minus}0.1 kG)/cos({theta}), H{sub c2}=8.4{plus_minus}0.2 kG/cos({phi}), and H{sub c3}=(6.6{plus_minus}0.2 kG)/sin({phi}), where {phi}={theta}{minus}45 is the angle from the [100] axis. The high-field saturated moment, M{sub sat}{approx}10{mu}{sub B}cos{theta} is consistent with the local moments being confined to the [110] direction. The locally saturated moments for fields between H{sub ci} (i=1,2,3) also manifest angular dependences that are consistent with combinations of local moments along [110] axes. Analysis of these data lead us to infer that the net distribution of moments is ({up_arrow}{down_arrow}{up_arrow}{down_arrow}{up_arrow}{down_arrow}) for H{lt}H{sub c1}, ({up_arrow}{up_arrow}{down_arrow}{up_arrow}{up_arrow}{down_arrow}) for H{sub c1}{lt}H{lt}H{sub c2}, ({up_arrow}{up_arrow}{r_arrow}{up_arrow}{up_arrow}{r_arrow}) for H{sub c2}{lt}H{lt}H{sub c3}, and ({up_arrow}{up_arrow}{up_arrow}{up_arrow}{up_arrow}{up_arrow}) for H{gt}H{sub c3}. {copyright} {ital 1997} {ital The American Physical Society}

  12. Influence of Ni substitution at B-site for Fe3+ ions on morphological, optical, and magnetic properties of HoFeO3 ceramics

    NASA Astrophysics Data System (ADS)

    Habib, Zubida; Majid, Kowsar; Ikram, Mohd.; Sultan, Khalid; Mir, Sajad Ahmad; Asokan, K.

    2016-05-01

    Present study reports the effect of Ni substitution at B-site in HoFeO3 on the morphological, optical and magnetic properties. These compounds were prepared by solid-state reaction method. Scanning electron microscope reveals an increase in average grain sizes with Ni concentration. Absorption and emission spectra show redshift in band gap with increase in Ni ion concentrations. The Tauc plots show direct allowed transitions. Temperature-dependent magnetization studies on these compounds revealed the transition from ferromagnetism to paramagnetism. There is separation between temperature at which zero-field-cooled and field-cooled occurs at varied temperature with Ni substitution. The separation effect is related to the impact of the paramagnetic Ho3+ ions, whose magnitude becomes more prominent at higher temperature. The value of squareness ratio in these materials is below 0.5 indicating presence of multidomain structures.

  13. The structure of new nickel(I) oxides: LnSr 5Ni 3O 8 (Ln = Y, Dy, Ho, Er and Tm)

    NASA Astrophysics Data System (ADS)

    James, M.; Attfield, J. P.

    1994-12-01

    Stoichiometric oxides of 3d 9 nickel(I), LnSr 5Ni 3O 8 (Ln = Y, Dy, Ho, Er and Tm), have been prepared through the hydrogen reduction of LnSr 5Ni 3O 11, resulting in a change from a tetragonal K 2NiF 4 type structure to an orthorhombic Sr 2CuO 3 arrangement in which {1}/{3} of the bridging oxygen atoms are missing from chains of apex-linked nickel oxide square planes.

  14. Sources of stress gradients in electrodeposited Ni MEMS.

    SciTech Connect

    Hearne, Sean Joseph; Floro, Jerrold Anthony; Dyck, Christopher William

    2004-06-01

    The ability of future integrated metal-semiconductor micro-systems such as RF MEMS to perform highly complex functions will depend on developing freestanding metal structures that offer improved conductivity and reflectivity over polysilicon structures. For example, metal-based RF MEMS technology could replace the bulky RF system presently used in communications, navigation, and avionics systems. However, stress gradients that induce warpage of active components have prevented the implementation of this technology. Figure 1, is an interference micrograph image of a series of cantilever beams fabricated from electrodeposited Ni. The curvature in the beams was the result of stress gradients intrinsic to the electrodeposition process. To study the sources of the stress in electrodeposition of Ni we have incorporated a wafer curvature based stress sensor, the multibeam optical stress sensor, into an electrodeposition cell. We have determined that there are two regions of stress induced by electrodepositing Ni from a sulfamate-based bath (Fig 2). The stress evolution during the first region, 0-1000{angstrom}, was determined to be dependent only on the substrate material (Au vs. Cu), whereas the stress evolution during the second region, >1000{angstrom}, was highly dependent on the deposition conditions. In this region, the stress varied from +0.5 GPa to -0.5GPa, depending solely on the deposition rate. We examined four likely sources for the compressive intrinsic stress, i.e. reduction in tensile stress, and determined that only the adatom diffusion into grain boundaries model of Sheldon, et al. could account for the observed compressive stress. In the presentation, we shall discuss the compressive stress generation mechanisms considered and the ramifications of these results on fabrication of electrodeposited Ni for MEMS applications.

  15. 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 PAGESBeta

    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.

  16. Magnetic Interactions in the Double Perovskites R2NiMnO6 (R = Tb, Ho, Er, Tm) Investigated by Neutron Diffraction.

    PubMed

    Retuerto, María; Muñoz, Ángel; Martínez-Lope, María Jesús; Alonso, José Antonio; Mompeán, Federico J; Fernández-Díaz, María Teresa; Sánchez-Benítez, Javier

    2015-11-16

    R2NiMnO6 (R = Tb, Ho, Er, Tm) perovskites have been prepared by soft-chemistry techniques followed by high oxygen-pressure treatments; they have been investigated by X-ray diffraction, neutron powder diffraction (NPD), and magnetic measurements. In all cases the crystal structure is defined in the monoclinic P21/n space group, with an almost complete order between Ni(2+) and Mn(4+) cations in the octahedral perovskite sublattice. The low temperature NPD data and the macroscopic magnetic measurements indicate that all the compounds are ferrimagnetic, with a net magnetic moment different from zero and a distinct alignment of Ni and Mn spins depending on the nature of the rare-earth cation. The magnetic structures are different from the one previously reported for La2NiMnO6, with a ferromagnetic structure involving Mn(4+) and Ni(2+) moments. This spin alignment can be rationalized taking into account the Goodenough-Kanamori rules. The magnetic ordering temperature (TCM) decreases abruptly as the size of the rare earth decreases, since TCM is mainly influenced by the superexchange interaction between Ni(2+) and Mn(4+) (Ni(2+)-O-Mn(4+) angle) and this angle decreases with the rare-earth size. The rare-earth magnetic moments participate in the magnetic structures immediately below TCM. PMID:26513539

  17. S-shaped decanuclear heterometallic [Ni8Ln2] complexes [Ln(III) = Gd, Tb, Dy and Ho]: theoretical modeling of the magnetic properties of the gadolinium analogue.

    PubMed

    Hossain, Sakiat; Das, Sourav; Chakraborty, Amit; Lloret, Francesc; Cano, Joan; Pardo, Emilio; Chandrasekhar, Vadapalli

    2014-07-14

    The reaction of 8-quinolinol-2-carboaldoxime (LH2) with Ni(II) and Ln(III) salts afforded the heterometallic decanuclear compounds [Ni8Dy2(μ3-OH)2(L)8(LH)2(H2O)6](ClO4)2·16H2O (1), [Ni8Gd2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](NO3)2·12H2O (2), [Ni8Ho2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](ClO4)2·2MeOH·12H2O (3) and [Ni8Tb2 (μ3-OH)2(L)8(LH)2(MeOH)4(OMe)2]·2CH2Cl2·8H2O (4). While compounds 1-3 are dicationic, compound 4 is neutral. These compounds possess an S-shaped architecture and comprise a long chain of metal ions bound to each other. In all the complexes, the eight Ni(II) and two Ln(III) ions of the multimetallic ensemble are hold together by two μ3-OH, eight dianionic (L(2-)) and two monoanionic oxime ligands (LH(-)) whereas compound 4 has two μ3-OH, eight dianionic (L(2-)), two monoanionic oxime ligands (LH(-)) and two terminal methoxy (MeO(-)) ligands. The central portion of the S-shaped molecular wire is made up of an octanuclear Ni(II) ensemble which has at its two ends the Ln(III) caps. Magnetic studies on 1-4 reveal that the magnetic interactions between neighboring metal ions are negligible at room temperature. On the other hand, at lower temperatures in all the compounds anti-ferromagnetic interactions seem to be dominated. Analysis of the magnetic data for the Gd(III) derivative indicates Ni(II)-Ni(II) anti-ferromagnetic interactions and Gd(III)-Ni(II) ferromagnetic interactions at low temperatures. A theoretical density functional study on the magnetic behavior of the Gd(III) derivative suggests that while the weak ferromagnetic interaction between Gd(III) and Ni(II) is in line with the expectation of the magnetic interactions between orthogonal d and f orbitals, antiferromagnetic Ni(II)-Ni(II) interactions are related to the wide Ni-O-Ni angles (∼102°) and quasi-planar conformation of the Ni2O2 core. PMID:24876072

  18. OH and HO2 Concentrations, Sources and Loss Rates During the Southern Oxidants Study in Nashville, Tennessee, Summer 1999

    SciTech Connect

    Martinez, M.; Harder, H.; Kovacs, T. A.; Simpas, J. B.; Bassis, J.; Lesher, R.; Brune, W. H.; Frost, G. J.; Williams, E. J.; Stroud, C. A.; Jobson, B Tom T.; Roberts, James M.; Hall, Samual R.; Shetter, Richard E.; Wert, B.; Fried, Alan; Alicke, B.; Stutz, Jochen P.; Young, V. L.; White, A. B.; Zamora, R. J.

    2003-10-14

    OH and HO2 mixing ratios and total OH reactivity were measured together with photolysis frequencies, NOx, O3, many VOCs and other trace gases during the midsummer 1999 SOS campaign in Nashville, TN. These measurements provided an excellent opportunity to study OH and HO2 (collectively called HOx), and their sources and sinks in a polluted metropolitan environment. HOx generally showed the expected diurnal evolution, with maxima around noon of up to about 0.8 pptv of OH and 80 pptv of HO2 during sunny days. Overall, daytime observed OH and HO2 were a factor of 1.4 times modeled values, within the combined 1s instrument and model uncertainties. The chain length of HOx, which is determined from the ratio of the measured total OH reactivity that cycles OH to the first-order loss rate of OH to HNO3 production, was on average 15-20 during daytime and ~5 during nighttime, in general agreement with expectations. However, differences occurred between observed HOx behavior and expectations from theory and models. First, HO2 was greater than expected during daytime when NO mixing ratios were high; ozone production did not decrease as expected when NO was greater than 2 ppbv. Ozone production determined by the imbalance of the NOx photostationary state, which was almost twice that from HO2, also shows this dependence on NO. Second, the calculated OH production rate, which should equal the measured OH loss rate because OH is in steady-state, is instead less than the measured OH loss rate by (1-2)x107 molecules cm-3 s-1, with low statistical significance during the day and high statistical significance at night. Third, surprisingly high OH and HO2 mixing ratios were often observed during nighttime. The nighttime OH mixing ratio and the HO2/OH ratio cannot be explained by known reaction mechanisms, even those involving O3 and alkenes. Because instrument tests have failed to reveal any instrument artifacts, more exotic chemicals or chemistry, such as OH adducts or other radicals

  19. OH and HO2 concentrations, sources, and loss rates during the Southern Oxidants Study in Nashville, Tennessee, summer 1999

    NASA Astrophysics Data System (ADS)

    Martinez, M.; Harder, H.; Kovacs, T. A.; Simpas, J. B.; Bassis, J.; Lesher, R.; Brune, W. H.; Frost, G. J.; Williams, E. J.; Stroud, C. A.; Jobson, B. T.; Roberts, J. M.; Hall, S. R.; Shetter, R. E.; Wert, B.; Fried, A.; Alicke, B.; Stutz, J.; Young, V. L.; White, A. B.; Zamora, R. J.

    2003-10-01

    OH and HO2 mixing ratios and total OH reactivity were measured together with photolysis frequencies, NOx, O3, many VOCs, and other trace gases during the midsummer 1999 SOS campaign in Nashville, Tennessee. These measurements provided an excellent opportunity to study OH and HO2 (collectively called HOx), and their sources and sinks in a polluted metropolitan environment. HOx generally showed the expected diurnal evolution, with maxima around noon of up to about 0.8 pptv of OH and 80 pptv of HO2 during sunny days. Overall, daytime observed OH and HO2 were a factor of 1.33 and 1.56 times modeled values, within the combined 2σ instrument and model uncertainties. The chain length of HOx, which is determined from the ratio of the measured total OH reactivity that cycles OH to the total HOx loss, was on average 3-8 during daytime and up to 3 during nighttime, in general agreement with expectations. However, differences occurred between observed HOx behavior and expectations from theory and models. First, HO2 was greater than expected during daytime when NO mixing ratios were high; ozone production did not decrease as expected when NO was greater than 2 ppbv. Ozone production determined by the imbalance of the NOx photostationary state, which was almost twice that from HO2, also shows this dependence on NO. Second, the calculated OH production rate, which should equal the measured OH loss rate because OH is in steady state, is instead less than the measured OH loss rate by (1-2) × 107 molecules cm-3 s-1, with low statistical significance during the day and high statistical significance at night. Third, surprisingly high OH and HO2 mixing ratios were often observed during nighttime. The nighttime OH mixing ratio and the HO2/OH ratio cannot be explained by known reaction mechanisms, even those involving O3 and alkenes. Because instrument tests have failed to reveal any instrument artifacts, more exotic chemicals or chemistry, such as OH adducts or other radicals that

  20. SOURCE APPORTIONMENT OF FINE PARTICULATE MATTER IN THE U.S. AND ASSOCIATIONS WITH LUNG INFLAMMATORY MARKERS IL -8, COX -2 AND HO -1

    EPA Science Inventory

    Associations are well established between particulate matter (PM) and increased human mortality and morbidity. The association between fine PM sources and lung inflammatory markers IL-8, COX-2, and HO-1 was evaluated in this study.

  1. Metal-insulator transitions, structural and microstructural evolution of RNiO{sub 3} (R = Sm, Eu, Gd, Dy, Ho, Y) perovskites: Evidence for room-temperature charge disproportionation in monoclinic HoNiO{sub 3} and YNiO{sub 3}

    SciTech Connect

    Alonso, J.A.; Martinez-Lope, M.J.; Casais, M.T.; Arangda, M.A.G.; Fernandez-Diaz, M.T.

    1999-05-26

    RNiO{sub 3} nickelates have been prepared under high oxygen pressure (R = Sm, Eu, Gd) or high hydrostatic pressure (R = Dy, Ho, Y) in the presence of KClO{sub 4}. The samples have been investigated at room temperature (RT) by synchrotron X-ray powder diffraction to follow the evolution of the crystal structures and microstructures along the series. The distortion of the orthorhombic (space group Pbnm) perovskite progressively increases along the series, leading for the smallest Ho{sup 3+} and Y{sup 3+} cations to a subtle monoclinic distortion (space group P2{sub 1}/n) which implies the splitting of the Ni positions in the crystal. This symmetry was confirmed by neutron powder diffraction; the crystal structures for R = Ho and Y were refined simultaneously from RT synchrotron and neutron powder diffraction data. In both perovskites the oxygen octahedra around Ni1 and Ni2 positions are significantly distorted, suggesting the manifestation of Jahn-Teller effect, which is almost absent in the nickelates` of lighter rare earths. The very distinct mean Ni-O bond distances observed for Ni1 and Ni2 atoms at RT, in the insulating regime, suggest the presence of a charge disproportionation effect, considered as driving force for the splitting of the Ni positions. The metal-insulator (MI) transitions for RNiO{sub 3} (R = Gd, Dy, Ho, Y), above room temperature, have been characterized by DSC. The transition temperatures for Gd, Dy, Ho, and Y oxides in the heating runs are 510.7, 563.9, 572.7, and 581.9 K, respectively. The increasing rate of T{sub MI} for Dy, Ho, and Y materials is lower than that expected from the variation of T{sub MI} for the larger rare earth perovskites. This is probably related to the subtle monoclinic distortion found for Ho and Y nickelates. The high-resolution synchrotron X-ray powder patterns have revealed changes in the microstructure along the series. Powder patterns for orthorhombic RNiO{sub 3} (R = Sm, Eu, Gd, Dy) display asymmetric tails for

  2. Mo2NiB2-type {Gd, Tb, Dy)2Ni2.35Si0.65 and La2Ni3-type {Dy, Ho}2Ni2.5Si0.5 compounds: Crystal structure and magnetic properties

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The crystal structure of new Mo2NiB2-type {Gd, Tb, Dy}2Ni2.35Si0.65 (Immm, No. 71, oI10) and La2Ni3-type {Dy, Ho}2Ni2.5Si0.5 (Cmce No. 64, oC20) compounds has been established using powder X-ray diffraction studies. Magnetization measurements show that the Mo2NiB2-type Gd2Ni2.35Si0.65 undergoes a ferromagnetic transition at 66 K, whereas isostructural Tb2Ni2.35Si0.65 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, Tb2Ni2.35Si0.65 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) μB at 2 K. The La2Ni3-type Dy2Ni2.5Si0.5 exhibits ferromagnetic like transition at 42 K with coexisting antiferromagnetic interactions and field induced metamagnetic transition below 17 K. The magnetocaloric effect of Gd2Ni2.35Si0.65, Tb2Ni2.35Si0.65 and Dy2Ni2.5Si0.5 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 Tb2Ni2.35Si0.65 and Dy2Ni2.35Si0.65 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.

  3. 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

  4. Pentanuclear heterometallic {Ni2Ln3} (Ln = Gd, Dy, Tb, Ho) assemblies. Single-molecule magnet behavior and multistep relaxation in the dysprosium derivative.

    PubMed

    Chandrasekhar, Vadapalli; Bag, Prasenjit; Kroener, Wolfgang; Gieb, Klaus; Müller, Paul

    2013-11-18

    The reaction between Ln(III) chloride and NiCl2·4H2O salts in presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the synthesis of four isostructural pentanuclear hetereometallic complexes [Ni2Dy3(LH)4]Cl (1), [Ni2Gd3(LH)4]Cl (2), [Ni2Tb3(LH)3(LH2)]Cl2 (3), [Ni2 Ho3 (LH)3 (LH2)]Cl2 (4) with unprecedented topology. Here the two compounds 1 are 2 are monocationic and crystallize in chiral space group, P2(1)2(1)2(1) whereas compounds 3 and 4 are dicationic and crystallize in achiral space group P2(1)/n. The total metal framework, {Ni2Ln3} unit is held by four triply deprotonated ligands [LH](3-) in 1 and 2 whereas in case of 3 and 4 three triply deprotonated [LH](3-) and one doubly deprotonated [LH2](2-) ligands are involved. In these complexes both the lanthanide ions and the nickel(II) ions are doubly bridged and the bridging is composed of oxygen atoms derived from either phenolate or ethoxide groups. The analysis of SQUID measurements reveal a high magnetic ground state and a slow relaxation of the magnetization with two relaxation regimes for 1. For the thermally activated regime we found an effective energy barrier of U(eff) = 85 K. Micro Hall probe loop measurements directly proof the single-molecule magnet (SMM) nature of 1 with a blocking temperature of T(B) = 3 K and an open hysteresis for sweep rates faster than 50 mT/s. PMID:24236759

  5. High-power Ho-doped all-fiber superfluorescent source pumped by a 1150  nm Raman fiber laser.

    PubMed

    Jin, Xiaoxi; Wang, Xiong; Wang, Xiaolin; Xiao, Hu; Zhou, Pu

    2014-12-10

    A broadband superfluorescent source based on 2 m long Ho-doped fiber and a 1150 nm high-power Raman fiber laser is reported. The optical spectrum of the superfluorescent source spans the range from 1930 to 2110 nm. The maximum output power is 1.5 W, and the spectral full width at half-maximum is about 30 nm. Two peaks are generated in an optical spectrum when output power of the Ho-doped superfluorescent source is beyond ∼200  mW. PMID:25608073

  6. Evolution of magnetic layers stacking sequence within the magnetic structure of Ho(CoxNi1-x)2B2C

    NASA Astrophysics Data System (ADS)

    ElMassalami, M.; Takeya, H.; Ouladdiaf, B.; Gomes, A. M.; Paiva, T.; dos Santos, R. R.

    2014-12-01

    We evaluated the influence of Co substitution on the magnetic structure of Ho(CoxNi1-x)2B2C (x=0.2, 0.4, 0.6, 0.8) using neutron diffraction, magnetization and specific heat studies. Different modes are stabilized: an AFM k=(0,0,1) mode for x=0.2, a spiral k=(0,0,0.49) mode for x=0.4, a spiral k=(0,0,0.26) mode for x=0.6, and a FM k=(0,0,0) mode for x=0.8. Recalling that for x=0.0, k=(0,0,1) while for x=1.0, k=(0,0,0), then all these magnetic structures can be visualized as a variation in the stacking sequence, along the z-axis, of the intra-planar FM-coupled Ho sheets as such Co substitution controls the z-component of the k=(0,0,ux) vector where ux=0,0.26,0.49, or 1. We discuss this inference and the observation that in spite of such a diversity of magnetic structures, the critical temperatures and the saturated moments are only weakly influenced by substitution.

  7. Electric Transport in R2MGe6 Ternary Compounds (R=La, Ce, Gd, Tb, Dy, Ho; M=Mn, Ni, Cu)

    SciTech Connect

    M. Konyk; B. Kuzhel; Yu. Stadnyk; Yu. Gorelenko; Ya. Mudryk; A. Waskiv

    2007-04-29

    Polycrystalline samples of the intermetallic compounds La{sub 2}MnGe{sub 6}, Ce{sub 2}MnGe{sub 6}, La{sub 2}CuGe{sub 6}, Ce{sub 2}CuGe{sub 6}, and R{sub 2}NiGe{sub 6} (R = Gd, Tb, Dy, Ho), which belong to the Ce{sub 2}CuGe{sub 6} type of structure (Amm2 or Cm2m space group), were studied by means of the electrical resistivity and differential thermopower measurements. They exhibit the metallic-like behavior in the temperature range from 5 to 290 K. The peculiarities in both resistivity and thermopower temperature dependencies correlate with corresponding magnetic transition T{sub tr} temperatures.

  8. Indium flux synthesis of RE4Ni2InGe4 (RE = Dy, Ho, Er, and Tm): an ordered quaternary variation on the binary phase Mg5Si6.

    PubMed

    Salvador, James R; Kanatzidis, Mercouri G

    2006-09-01

    The quaternary compounds RE4Ni2InGe4 (RE = Dy, Ho, Er, and Tm) were obtained as large single crystals in high yields from reactions run in liquid In. The title compounds crystallize in the monoclinic C2/m space group with the Mg(5)Si(6) structure type with lattice parameters a = 15.420(2) A, b = 4.2224(7) A, c = 7.0191(11) A, and beta = 108.589(2) degrees for Dy4Ni2InGe4, a = 15.373(4) A, b = 4.2101(9) A, c = 6.9935(15) A, and beta = 108.600(3) degrees for Ho4Ni2InGe4, a = 15.334(7) A, b = 4.1937(19) A, c = 6.975(3) A, and beta =108.472(7) degrees for Er4Ni2InGe4, and a = 15.253(2) A, b = 4.1747(6) A, c = 6.9460(9) A, and beta = 108.535(2) degrees for Tm4Ni2InGe4. RE4Ni2InGe4 formed in liquid In from a melt that was rich in the rare-earth component. These compounds are polar intermetallic phases with a cationic rare-earth substructure embedded in a transition metal and main group matrix. The rare-earth atoms form a highly condensed network, leading to interatomic distances that are similar to those found in the elemental lanthanides themselves. The Dy and Ho analogues display two maxima in the susceptibility, suggesting antiferromagnetic ordering behavior and an accompanying spin reorientation. The Er analogue shows only one maximum in the susceptibility, and no magnetic ordering was observed for the Tm compound down to 2 K. PMID:16933908

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

    PubMed

    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. PMID:20687747

  10. 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.

  11. Prediction of 4H-SiC betavoltaic microbattery characteristics based on practical Ni-63 sources.

    PubMed

    Gui, Gui; Zhang, Kan; Blanchard, James P; Ma, Zhenqiang

    2016-01-01

    We have investigated the performance of 4H-SiC betavoltaic microbatteries under exposure to the practical Ni-63 sources using the Monte Carlo method and Synopsys® Medici device simulator. A typical planar p-n junction betavoltaic device with the Ni-63 source of 20% purity on top is modeled in the simulation. The p-n junction structure includes a p+ layer, a p- layer, an n+ layer, and an n- layer. In order to obtain an accurate and valid predication, our simulations consider several practical factors, including isotope impurities, self-absorption, and full beta energy spectra. By simulating the effects of both the p-n junction configuration and the isotope source thickness on the battery output performance, we have achieved the optimal design of the device and maximum energy conversion efficiency. Our simulation results show that the energy conversion efficiency increases as the doping concentration and thickness of the p- layer increase, whereas it is independent of the total depth of the p-n junction. Furthermore, the energy conversion efficiency decreases as the thickness of the practical Ni-63 source increases, because of self-absorption in the isotope source. Therefore, we propose that a p-n junction betavoltaic cell with a thicker and heavily doped p- layer under exposure to a practical Ni-63 source with an appreciable thickness could produce the optimal energy conversion efficiency. PMID:26583261

  12. Spectroscopic investigation of Yb,Ho,Pr:YAG as a 3 μm laser source

    NASA Astrophysics Data System (ADS)

    Stites, Ronald W.; Harris, Thomas R.

    2016-03-01

    In addition to the well-established 5I7 to 5I8 transition at 2.09 μm in holmium doped laser materials, there also exists a less energetic transition from the 5I6 level to 5I7 at 2.95 μm. As there has been a recent increase in interest and applications for 3.0 μm light, this material stands to be a viable alternative to other rare earth doped laser systems. Unfortunately, the wavelength required to directly pump the 5I6 level at 1.13 μm is not convenient for commercial laser diodes. Furthermore, the emission lifetime of the 5I7 state is longer than the 5I6 level, leading to a suppression of lasing due to "bottlenecking" in the material. To overcome these effects, we investigated the activation and deactivation of holmium doped yttrium aluminum garnet (YAG) using ytterbium and praseodymium respectively. By including ytterbium ions in the host material, readily available 914 nm diode light can be used to resonantly excite the 5I6 level in holmium. Similarly, the presence of praseodymium resonantly de-excites the 5I7 state, reducing its lifetime, and making the material more suitable for lasing. Here, we report the absorption and photoluminescence spectra of this triply doped Yb,Ho,Pr:YAG crystal. In addition, the emission lifetime for both the 2.09 μm and 2.95 μm transitions are reported and compared to a Yb,Ho:YAG control sample.

  13. Rare earth-copper-magnesium compounds RECu 9Mg 2 ( RE=Y, La-Nd, Sm-Ho, Yb) with ordered CeNi 3-type structure

    NASA Astrophysics Data System (ADS)

    Solokha, P.; Pavlyuk, V.; Saccone, A.; De Negri, S.; Prochwicz, W.; Marciniak, B.; Różycka-Sokołowska, E.

    2006-10-01

    A series of ternary compounds RECu 9Mg 2 ( RE=Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb) have been synthesized via induction melting of elemental metal ingots followed by annealing at 400 °C for 4 weeks. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS) was used for examining microstructure and phase composition. These phases crystallize with an ordered version of the binary hexagonal structure type first reported for CeNi 3. The crystal structure was solved for TbCu 9Mg 2 from single crystal X-ray counter data (TbCu 9Mg 2-structure type, P6 3/mmc-space group, hP24-Pearson symbol, a=0.49886 (7) nm, c=1.61646 (3) nm, RF=0.0474 for 190 unique reflections). The Rietveld refinement of the X-ray powder diffraction patterns of RECu 9Mg 2 confirmed the same crystal structure for the reported rare earth metals. The unit cell volumes for RECu 9Mg 2 smoothly follow the lanthanide contraction. The existence of a RECu 9Mg 2 phase was excluded for RE=Er and Tm under the investigated experimental conditions.

  14. 78 FR 68465 - NiSource, Inc.; Record of Decision, Habitat Conservation Plan, Environmental Impact Statement...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-14

    ... cooperating agencies. Availability of the FEIS was published in the Federal Register on June 7, 2013 (78 FR 34402), and June 14, 2013 (78 FR 35928). Background NiSource, Inc., headquartered in Merrillville..., the Service published a Notice of Intent (NOI) to prepare an EIS in the Federal Register (72 FR...

  15. 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.

  16. Effect of Carbon Sources on the Catalytic Performance of Ni/β-Mo2C.

    PubMed

    Zeng, Li-Zhen; Zhao, Shao-Fei; Li, Wei-Shan

    2015-06-01

    In this paper, Ni/β-Mo2C(S) and Ni/β-Mo2C(G) were prepared from solution-derived precursor with two different carbon sources (starch and glucose) and tested as anodic noble-metal-free catalysts in air-cathode microbial fuel cells (MFCs). The carburized catalyst samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET). The activity of the electrocatalyst towards the oxidation of several common microbial fermentation products (formate, lactate, and ethanol) was studied for MFC based on Klebsiella pneumoniae conditions. The composite MFC anodes were fabricated, and their catalytic behavior was investigated. With different carbon sources, the crystalline structure does not change and the crystallinity and surface area increase. The electrocatalytic experiments show that the Ni/β-Mo2C(G) gives the better bio- and electrocatalytic performance than Ni/β-Mo2C(S) due to its higher crystallinity and BET surface area. PMID:25877400

  17. Observation and modelling of OH and HO2 concentrations in Beijing and Pearl River Delta summer 2006: missing OH source in VOC rich atmosphere

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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) and the CAREBEIJING2006 (Campaigns of Air Quality Research in Beijing and Surrounding Region, 2006) campaigns at rural sites close to the megacities of Guangzhou and Beijing, respectively. In PRD, the observed daily maximum OH and HO2 concentrations reached daily peak values of (15~--~26)±106 cm-3 and (3~--~25)±108 cm-3, respectively. In Beijing, the corresponding values were about (4~--~17)±106 cm-3 and (2~--~24)±108 cm-3. At both sites, the measured OH concentrations were much higher than can be explained by current chemical box models when NOx is low, pointing to a missing OH source in VOC rich air. In this presentation, we report the observed and modelled HOx concentrations, depict the general feature of the HOx system through an empirical analysis, and examine different mechanistic proposals to explain the missing OH source (Hofzumahaus et al. 2009; Lu et al., 2011). Overall, we conclude that a missing OH recycling of type HO2->OH is required for these VOC rich air masses in the transient regime between biogenic and urban influences. Recently published mechanistic updates of isoprene chemistry (e.g. MIM2+ and LIM0) developed for forest regions are not able to reproduce the observed OH in both PRD and Beijing.

  18. 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.

  19. 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)

  20. Night-time measurements of HOx during the RONOCO project and analysis of the sources of HO2

    NASA Astrophysics Data System (ADS)

    Walker, H. M.; Stone, D.; Ingham, T.; Vaughan, S.; Cain, M.; Jones, R. L.; Kennedy, O. J.; McLeod, M.; Ouyang, B.; Pyle, J.; Bauguitte, S.; Bandy, B.; Forster, G.; Evans, M. J.; Hamilton, J. F.; Hopkins, J. R.; Lee, J. D.; Lewis, A. C.; Lidster, R. T.; Punjabi, S.; Morgan, W. T.; Heard, D. E.

    2015-07-01

    Measurements of the radical species OH and HO2 were made using the fluorescence assay by gas expansion (FAGE) technique during a series of night-time and daytime flights over the UK in summer 2010 and winter 2011. OH was not detected above the instrument's 1σ limit of detection during any of the night-time flights or during the winter daytime flights, placing upper limits on [OH] of 1.8 × 106 molecule cm-3 and 6.4 × 105 molecule cm-3 for the summer and winter flights, respectively. HO2 reached a maximum concentration of 3.2 × 108 molecule cm-3 (13.6 pptv) during a night-time flight on 20 July 2010, when the highest concentrations of NO3 and O3 were also recorded. An analysis of the rates of reaction of OH, O3, and the NO3 radical with measured alkenes indicates that the summer night-time troposphere can be as important for the processing of volatile organic compounds (VOCs) as the winter daytime troposphere. An analysis of the instantaneous rate of production of HO2 from the reactions of O3 and NO3 with alkenes has shown that, on average, reactions of NO3 dominated the night-time production of HO2 during summer and reactions of O3 dominated the night-time HO2 production during winter.

  1. 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). PMID:24997934

  2. Photooxidation of water by NiTiO3 deposited from single source precursor [Ni2Ti2(OEt)2(micro-OEt)6(acac)4] by AACVD.

    PubMed

    Tahir, Asif Ali; Mazhar, Muhammad; Hamid, Mazhar; Wijayantha, K G Upul; Molloy, Kieran C

    2009-05-21

    A single-source heterobimetallic complex Ni2Ti2(OEt)2(mu-OEt)6(acac)4 (1) (acac=2,4-pentanedionate), having a low decomposition temperature and sufficient solubility in organic solvents, was synthesized by simple chemical techniques in high yield and analyzed by melting point, FTIR, single crystal X-ray analysis and thermal analysis. The TGA analysis proved that complex (1) underwent facile thermal decomposition at 500 degrees C to give NiTiO3 residue. In-house designed aerosol assisted chemical vapor deposition equipment was used to deposit high quality thin films of NiTiO3 on a SnO2 coated conducting glass substrate at 500 degrees C. An XRD analysis of the thin films proved the formation of crystalline NiTiO3 with average grain size 42 nm. Scanning electron microscopic studies (SEM) show that the thin films consist of flat, plate-like nanoparticles. The current-potential characteristics recorded under AM1.5 illumination indicate that NiTiO3 thin films are anodic and the photocurrent density at 1.23 V vs RHE (Reversible Hydrogen Electrode) is about 40 microA cm(-2). PMID:19417932

  3. Magnetic structures of R 5Ni2In4 and R 11Ni4In9 (R  =  Tb and Ho): strong hierarchy in the temperature dependence of the magnetic ordering in the multiple rare-earth sublattices

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The magnetic properties and magnetic structures of the R 5Ni2In4 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 R 5Ni2In4 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. A transition at T C  =  125 K in Tb5Ni2In4 [κ 1  =  (0, 0, 0)] leads to a ferro/ferrimagnetic order where the magnetic ordering in one of the three R-sublattices leads to the ordering of another one; the third sublattice stays non-magnetic. New magnetic Bragg peaks appearing below T N  =  20 K can be indexed with the incommensurate magnetic propagation vector κ 2  =  (0, 0.636, ½) at T N  =  20 K a cycloidal spin order, which acts mostly upon the third R-sublattice, occurs. Ho5Ni2In4 establishes first antiferromagnetism [κ  =  (0, 0, 0)] at T N  =  31 K on two R-sublattices; then the system becomes ferro/ferrimagnetic at T C  =  25 K with the third sublattice ordering as well. Tb11Ni4In9 has three magnetic transitions at T C  =  135 K, T N1  =  35 K and at T N2  =  20 K they are respectively coupled to the appearance of different propagation vectors [κ 1  =  (0, 0, 0), κ 2  =  (0, 0, ½), κ 3  =  (0, 1, ½)], which themselves are operating differently on the five different R-sublattices. Two sublattices remain mostly ferromagnetic down to lowest temperature while the three others are predominantly coupled antiferromagnetically. In Ho11Ni4In9 a purely antiferromagnetic order, described by four different

  4. The potential for ductility enhancement from surface and interface dislocation sources in NiAl

    NASA Technical Reports Server (NTRS)

    Noebe, R. D.; Bowman, R. R.; Kim, J. T.; Larsen, M.; Gibala, R.

    1990-01-01

    Limited ductility and toughness of NiAl and related aluminides near room temperature pose major problems in their potential application as structural materials. An analysis of these problems is presented as part of a review of the flow and fracture behavior of binary NiAl. Following this discussion is a demonstration that conditions of elastic and plastic constraint associated with phase boundaries afforded by surface films, internal lamellae, or precipitates may introduce sufficient densities of mobile dislocations to enhance the ductility of NiAl-based materials by significant amounts. Examples of this behavior are presented for several model materials, including 001- and 123-oriented single crystals of oxide-coated NiAl, directionally solidified beta-gamma-prime (Ni70Al30) and beta-gamma (Ni50Fe30Al20) in situ composites, and several NiAl/precipitate systems. The nature of the resulting dislocation substructures and the effects of several materials variables are described.

  5. Growth mechanism of thin films of yttria-stabilized zirconia by chemical vapor infiltration using NiO-ceria substrate as oxygen source

    NASA Astrophysics Data System (ADS)

    Kikuchi, Kenji; Okada, Koji; Mineshige, Atsushi

    The deposition of yttria-stabilized zirconia films on a NiO-ceria substrate by chemical vapor infiltration (CVI) using ZrCl 4 and YCl 3 as metal sources and NiO-ceria as oxygen source was studied. The resultant films were cubic YSZ with a Y 2O 3 content of 3.7-4.2 mol%, and were transparent and strong. A NiO content of NiO-ceria above 60 mol% increases the growth rate of the YSZ film from about 5 to 25 μm over 2 h, indicating that chemical vapor deposition (CVD) occurred in addition to electrochemical vapor deposition (EVD), whereas NiO contents below 60 mol% does not affect the growth rate, indicating that only electrochemical vapor deposition occurred. The growth mechanism of the YSZ film is determined and a YSZ thin film is successfully fabricated on NiO-ceria to improve mechanical strength.

  6. Synthesis and characterization of NiO strips from a single source

    NASA Astrophysics Data System (ADS)

    Ni, Xiaomin; Zhao, Qingbiao; Zhou, Fu; Zheng, Huagui; Cheng, Jing; Li, Beibei

    2006-03-01

    One-dimensional strips of NiO, comprising self-assembled nanoparticles, were created through a thermal decomposition method using nickel dimethylglyoximate (Ni(dmg) 2) as starting agent. The morphology of the precursor was maintained during the heating process, while the size of the subunits was tailored by adjusting the calcining temperature. Raman spectrum revealed that many vacancies existed in the product which was obtained at a relatively lower temperature. Thus-prepared nanostructured NiO with subunits of about 15 nm exhibited a first discharge specific capacity of 784 mA h g -1 vs. Li metal, much higher than that of the sample with bigger building blocks.

  7. 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.

  8. Partitioning of Ni between olivine and siliceous eclogite partial melt: experimental constraints on the mantle source of Hawaiian basalts

    NASA Astrophysics Data System (ADS)

    Wang, Zhengrong; Gaetani, Glenn A.

    2008-05-01

    Olivine is abundant in Earth’s upper mantle and ubiquitous in basaltic lavas, but rarely occurs in eclogite. Partial melts of eclogite are, therefore, not in equilibrium with olivine, and will react with peridotite as they migrate through the upper mantle. If such melts erupt at Earth’s surface, their compositions will be highly modified and they may be olivine-saturated. We investigated experimentally the reaction between olivine and siliceous eclogite partial melt, and determined element partitioning between olivine and the melt produced by this reaction. Our results demonstrate that mixing of reacted eclogite partial melt with primitive basalt is capable of producing the positive correlation between melt SiO2 content and olivine Ni content observed in some Hawaiian lavas. Experiments were carried out by equilibrating eclogite partial melt or basalt with San Carlos olivine at 1 bar and 1,201 1,350°C. Our results show that eclogite partial melts equilibrated with mantle olivine retain their high SiO2, low FeO and MgO characteristics. Further, olivine-melt partition coefficients for Ni measured in these experiments are significantly larger than for basalt. Mixing of these melts with primitive Hawaiian tholeiitic lavas results in crystallization of high-Ni olivines similar to those in Makapuu-stage Koolau lavas, even though the mixed magmas have only moderate Ni contents. This results from a hyperbolic increase of the Ni partition coefficient with increasing polymerization of the mixed melt. Note that while eclogite partial melt in contact with peridotite will equilibrate with pyroxene as well as olivine, this will have the effect of buffering the activity of SiO2 in the reacted melt at a higher level. Therefore, an eclogite partial melt equilibrated with harzburgite will have higher SiO2 than one equilibrated with dunite, enhancing the effects observed in our experiments. Our results demonstrate that an olivine-free “hybrid” pyroxenite source is not

  9. 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.

  10. 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. PMID:26992542

  11. In Situ TiC-Reinforced Ni-Based Composite Coating Prepared by Flame Spraying Using Sucrose as the Source of Carbon

    NASA Astrophysics Data System (ADS)

    Wang, Haitao; Zhang, Shouquan; Zhu, Jinglei; Huang, Jihua; Liu, Huiyuan; Zhang, Hua

    2009-03-01

    A Ni-Ti-C composite powder for Reactive Thermal Spraying is made by heating a mixture of titanium, nickel, and sucrose to carbonize the sucrose, which is used as the source of carbon. The carbon obtained by pyrolysis of sucrose is a reactive constituent as well as the binder in the composite powder. The titanium and nickel particles are bound by the carbon to form granules of the composite powder. This powder feedstock was used to prepare in situ TiC-reinforced Ni-based composite coating by oxyacetylene flame spraying. The TiC-Ni composite coating is made of TiC, Ni, and some Ni3Ti. In the coating, a mass of fine TiC particles is uniformly distributed within the metallic matrix. The microhardness and surface hardness of the coating are, respectively, 1433 HV0.2kg and 62 ± 6 (HR30N). The wear resistance is much better for the TiC-Ni composite coating than for the substrate and Ni60 coating.

  12. Relationships between the Maritime Continent Heat Source and the El Niño-Southern Oscillation Phenomenon.

    NASA Astrophysics Data System (ADS)

    McBride, John L.; Haylock, Malcolm R.; Nicholls, Neville

    2003-09-01

    Various earlier studies have demonstrated that rainfall in the Maritime Continent-Indonesia region is strongly related to the El Niño-Southern Oscillation (ENSO) during the dry half of the year but has a very weak association with ENSO during the summer-wet season months. This relationship is investigated over a wider domain through the use of outgoing longwave radiation (OLR) data as a proxy for rainfall.Consistent with the hypothesis of Haylock and McBride, it is found that the large-scale structure of the low-order empirical orthogonal functions (EOFs) of OLR have a strong resemblance to the patterns of correlation between OLR and the Southern Oscillation index (SOI). This supports the hypothesis that the predictable component of rainfall is determined by the component that is spatially coherent, as quantified through EOF analysis.As was found earlier with rainfall, the region of largest correlation between interannual OLR anomalies and the SOI lies in the winter hemisphere. The predictable component of OLR (or rainfall) remains in the region of the Maritime Continent throughout the year and thus does not accompany the minimum OLR (maximum rainfall) during its annual interhemispheric progression as the major monsoon heat source.The sign of the OLR-SOI relationship is such that the Maritime Continent has increased rainfall during a La Niña or cold event. Patterns of correlation between sea surface temperature and the SOI show the existence of a region to the east of the Maritime Continent whereby sea surface temperature anomalies are positive during these (La Niña) conditions. This is in the sense of a direct relationship, that is, positive sea surface temperature anomalies corresponding to increased rainfall.The annual cycle of the sea surface temperature structure of ENSO is represented by the first EOF of the interannual sea surface temperature series for each separate calendar month. The region of the sea surface temperature anomaly giving the direct

  13. Mechanical annealing and source-limited deformation in submicrometre-diameter Ni crystals.

    PubMed

    Shan, Z W; Mishra, Raja K; Syed Asif, S A; Warren, Oden L; Minor, Andrew M

    2008-02-01

    The fundamental processes that govern plasticity and determine strength in crystalline materials at small length scales have been studied for over fifty years. Recent studies of single-crystal metallic pillars with diameters of a few tens of micrometres or less have clearly demonstrated that the strengths of these pillars increase as their diameters decrease, leading to attempts to augment existing ideas about pronounced size effects with new models and simulations. Through in situ nanocompression experiments inside a transmission electron microscope we can directly observe the deformation of these pillar structures and correlate the measured stress values with discrete plastic events. Our experiments show that submicrometre nickel crystals microfabricated into pillar structures contain a high density of initial defects after processing but can be made dislocation free by applying purely mechanical stress. This phenomenon, termed 'mechanical annealing', leads to clear evidence of source-limited deformation where atypical hardening occurs through the progressive activation and exhaustion of dislocation sources. PMID:18157134

  14. Producing Ni-rich olivine phenocrysts by mixing partial melts of eclogite and peridotite: an alternative to an olivine-free source for Hawaiian shield basalts

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Gaetani, G.

    2007-12-01

    It has been posited that presence of unusually Ni-rich (2500-4000 ppm) magnesian olivine phenocrysts in SiO2-enriched Hawaiian shield-building basalts, most notably the Koolau lavas, is inconsistent with a deep, olivine-bearing source rock. Instead, Sobolev et al. (2005) proposed that these lavas are generated by a multi- stage process in which partial melts of eclogite react with peridotite within the plume to form an olivine-free source rock with high Ni concentration. As the plume continues to ascend, partial melts of this "hybrid" pyroxenite mix with peridotite melts to produce SiO2- enriched Hawaiian shield-building lavas that crystallize high-Ni olivine. This model has also been used to argue for significant amounts of "hybrid" pyroxenite in the source regions of lavas from other ocean islands, continental basalts, and even MORB, implying that the upper mantle is highly heterogeneous (Sobolev et al., 2007). New experimental results demonstrate that Ni-rich magnesian olivine crystallizes from mixtures of peridotite partial melt and Ni-poor eclogite partial melt that have equilibrated with mantle olivine. This occurs because the concentration of Ni decreases linearly as eclogite partial melt is added to peridotite partial melt, whereas changing major element composition of the mixed melts causes DNi to increase hyperbolically. Experiments were conducted in which either (1) siliceous partial melt of eclogite or (2) primitive basalt was equilibrated with San Carlos olivines at 1 bar and 1201-1350°C. Experimental results demonstrate that eclogite partial melts in equilibrium with mantle olivine retain their high SiO2, low FeO and MgO characteristics. Theoretical modeling calibrated from these experimental results suggest that reaction of siliceous eclogite melt with mantle olivine at low pressure produces a melt containing ~300 ppm Ni. Despite its low Ni content, mixing of this melt with peridotite partial melt produces a high SiO2 melt that crystallizes Ni

  15. Systematic Study of a Family of Butterfly-Like {M2Ln2} Molecular Magnets (M = Mg(II), Mn(III), Co(II), Ni(II), and Cu(II); Ln = Y(III), Gd(III), Tb(III), Dy(III), Ho(III), and Er(III)).

    PubMed

    Moreno Pineda, Eufemio; Chilton, Nicholas F; Tuna, Floriana; Winpenny, Richard E P; McInnes, Eric J L

    2015-06-15

    A family of 3d-4f [M(II)2Ln(III)2(μ3-OH)2(O2C(t)Bu)10](2-) "butterflies" (where M(II) = Mg, Co, Ni, and Cu; Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) and [Mn(III)2Ln(III)2(μ3-O)2(O2C(t)Bu)10](2-) molecules (where Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) has been synthesized and characterized through single-crystal X-ray diffraction, SQUID magnetometry, and ab initio calculations. All dysprosium- and some erbium-containing tetramers showed frequency-dependent maxima in the out-of-phase component of the susceptibility associated with slow relaxation of magnetization, and hence, they are single-molecule magnets (SMMs). AC susceptibility measurements have shown that the SMM behavior is entirely intrinsic to the Dy and Er sites and the magnitude of the energy barrier is influenced by the interactions between the 4f and the 3d metal. A trend is observed between the strength of the 3d-4f exchange interaction between and the maximum observed in the χ″M(T). PMID:26016421

  16. 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.

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  19. The study of Nickel Resistant Bacteria (NiRB) isolated from wastewaters polluted with different industrial sources

    PubMed Central

    2014-01-01

    Background Pollution due to the heavy metals is a problem that may have negative consequences on the hydrosphere. One of the best procedures in removing the toxic metals from the environment is using metal resistant bacteria. Results In the present study eight nickel resistant bacteria were isolated from industrial wastewaters. Three of them were selected as the most resistant based on their Maximum tolerable concentration (8, 16 and 24 mM Ni2+). Their identification was done according to morphological, biochemical characteristics and 16SrDNA gene sequencing and they were identified as Cupriavidus sp ATHA3, Klebsiella oxytoca ATHA6 and Methylobacterium sp ATHA7. The accession numbers assigned to ATHA3, ATHA6 and ATHA7 strains are JX120152, JX196648 and JX457333 respectively. The Growth rate of the most resistant isolate, Klebsiella oxytoca strain ATHA6, in the presence of Ni2+ and the reduction in Ni2+ concentration was revealed that K oxytoca ATHA6 could decrease 83 mg/mL of nickel from the medium after 3 days. Conclusion It can be concluded that the identified Ni resistant bacteria could be valuable for the bioremediation of Ni polluted waste water and sewage. PMID:24475932

  20. 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.

  1. Determination of L X-ray fluorescence parameters for Ho, Lu, W, Hg and Bi.

    PubMed

    Turhan, M F; Durak, R; Akman, F

    2014-07-01

    In this work, L X-ray fluorescence cross sections, L sub-shell fluorescence yields and level widths and radiative vacancy transfer probabilities of L sub-shells to Mi, Ni and Oi sub-shells were measured for the elements Ho, Lu, W, Hg and Bi. Energy dispersive X-ray fluorescence (EDXRF) technique was used to measure L X-ray photons. To obtain related parameters, we used 59.54 keV gamma photons of (241)Am radioactive point source. Emitted L X-ray photons from targets were collected by means of a Si(Li) detector with resolution of 180 eV at 5.9 keV. The present results are generally in a good agreement with theoretical calculations and the other results obtained in the literature, within their range considering experimental uncertainty. PMID:24631748

  2. Nonsuperconductivity and magnetic features of the intermetallic borocarbide HoCo2B2C

    NASA Astrophysics Data System (ADS)

    Rapp, R. E.; Massalami, M. El

    1999-08-01

    Intrigued by the exotic features of the low-temperature superconducting and magnetic phase diagram of HoNi2B2C, this work searched for similar features in the isomorphous HoCo2B2C [LuNi2B2C-type structure, a=3.500(3) Å, c=10.590(9) Å]. In contrast to the former, no superconductivity is observed down to 30 mK, indicative of a relative lattice stiffening and a reduction in N(EF). The magnetic ordering of the Ho sublattice sets in at TN=5.4(1) K (Co-sublattice carries no magnetic moment). The magnetic entropy up to 10 K is suggestive of an electronic ground-state doublet. No field-induced cascade of magnetic phase transitions was observed in the range 1.8 KHo3+ nuclear Schottky-type contribution: the derived hyperfine parameters are comparable to that of those of HoNi2B2C and Ho metal. The T1 event, evident also in χac(T), is probably a manifestation of an order-to-order magnetic phase transition.

  3. HOED: Hypermedia Online Educational Database.

    ERIC Educational Resources Information Center

    Duval, E.; Olivie, H.

    This paper presents HOED, a distributed hypermedia client-server system for educational resources. The aim of HOED is to provide a library facility for hyperdocuments that is accessible via the world wide web. Its main application domain is education. The HOED database not only holds the educational resources themselves, but also data describing…

  4. 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…

  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. Multi-element determination of Cu, Fe, Ni and Zn content in vegetable oils samples by high-resolution continuum source atomic absorption spectrometry and microemulsion sample preparation.

    PubMed

    Nunes, Luana S; Barbosa, José T P; Fernandes, Andréa P; Lemos, Valfredo A; Santos, Walter N L Dos; Korn, Maria Graças A; Teixeira, Leonardo S G

    2011-07-15

    The aim of this work was to evaluate the microemulsification as sample preparation procedure for determination of Cu, Fe, Ni and Zn in vegetable oils samples by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). Microemulsions were prepared by mixing samples with propan-1-ol and aqueous acid solution, which allowed the use of inorganic aqueous standards for the calibration. To a sample mass of 0.5g, 100μL of hydrochloric acid and propan-1-ol were added and the resulting mixture diluted to a final volume of 10mL. The sample was manually shaken resulting in a visually homogeneous system. The main lines were selected for all studied metals and the detection limits (3σ, n=10) were 0.12, 0.62, 0.58 and 0.12mgkg(-1) for Cu, Fe, Ni and Zn, respectively. The relative standard deviation (RSD) ranged from 5% to 11 % in samples spiked with 0.25 and 1.5μgmL(-1) of each metal, respectively. Recoveries varied from 89% to 102%. The proposed method was applied to the determination of Cu, Fe, Ni and Zn in soybean, olive and sunflower oils. PMID:23140735

  7. Tropospheric HO determination by FAGE

    NASA Astrophysics Data System (ADS)

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

    1986-12-01

    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.

  8. 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.

  9. Rotational Spectroscopic Studies and Observational Searches for HO3

    NASA Astrophysics Data System (ADS)

    Widicus Weaver, Susanna

    Interstellar chemistry is largely driven by reactions of unstable molecules that serve as reaction intermediates in terrestrial chemistry. One such class of compounds are weakly-bound clusters. These clusters could form in interstellar environments through radiative association reactions, but their identification and characterization in interstellar environments is limited by a lack of rotational spectral information. One such species is HO3, which could be formed in the interstellar medium from O2 and OH. HO3 has been studied extensively in the infrared, and there are a few microwave spectral studies that have also been reported. However, no millimeter or submillimeter spectral information is available to guide astronomical observations. In this talk, we will present the laboratory characterization of trans -HO3 and trans -DO3 from 70 to 450 GHz using our newly developed fast sweeping technique. The molecular constants have been significantly refined, and additional higher order centrifugal distortion constants have been determined. We will also present an initial observational search for HO3 in 32 star forming regions. Although no HO3 lines have been detected thus far, strict upper limits can be placed on the HO3 column density in these sources based on this analysis. Additional Authors: Luyao Zou, Brian M. Hays.

  10. Determination of the K absorption edge energy of Ho in element and its compounds using the bremsstrahlung technique

    NASA Astrophysics Data System (ADS)

    Niranjana, K. M.; Badiger, N. M.

    2013-05-01

    The K shell binding energies of Ho in element and in compounds Ho2O3 and HoF3 have been measured for the first time by adopting a novel method. The method involves a weak beta source, an external bremsstrahlung (EB) converter, element and compound targets and a high-resolution HPGe detector coupled to a 16K multichannel analyser. A spectrum of continuous EB photons, produced by the interaction of beta particles from a 90Sr-90Y radioactive source with an iron foil, is allowed to pass through the element and compound targets of Ho. The spectrum of transmitted EB photons is measured with a high-resolution HPGe detector spectrometer. The transmitted spectrum shows a sudden drop in intensity at K shell binding energy of the target. Such a sudden drop, which is essentially due to the onset of the K shell photoelectric effect, has been used to determine the K shell binding energy of Ho in element. The K shell binding energies of Ho in Ho2O3 and HoF3 compounds have also been determined using the same technique. From these data, the chemical shift in the K shell binding energy has been measured. It is found to be positive for Ho2O3 and negative for HoF3, indicating the dependence of the chemical shift on the crystal structure.

  11. Hyperfine structure in the X8, A[19.1]9 and B[21.68]8 states of HoF and X8 and A[15.6]9 state of HoCl

    NASA Astrophysics Data System (ADS)

    Dick, M. J.; Linton, C.; Adam, A. G.

    2015-02-01

    High resolution spectra of holmium monofluoride, HoF and holmium monochloride, HoCl, prepared in a laser ablation source, have been obtained using laser induced fluorescence. Spectra of the A[19.1]9-X8 0-0 and 1-0 and B[21.68]8-X8 0-0 bands of HoF and the A[15.6]9-X8 0-0 band of HoCl all show resolved hyperfine structure. Analysis of the spectra yielded magnetic hyperfine parameters, h = 0.2240(5), 0.2210(6), 0.2177(6) and 0.2488(5) cm-1 for the X (v = 0), A (v = 0 and 1) and B (v = 0) states of HoF and 0.2355(32) and 0.2448(29) cm-1 for the X (v = 0) and A (v = 0) states of HoCl, respectively. The following quadrupole coupling constants were obtained for the above six states; eQq0(HoF) = -0.0874(67), -0.0586(44), -0.0579(56), -0.0840(64) cm-1 and eQq0(HoCl) = -0.082(11), -0.060(11) cm-1. Comparison with previously determined values for HoO and HoS show that the ground state magnetic hyperfine structure in HoF and HoCl is entirely due to the Ho 4f electron and is consistent with the ground state, X8, configuration of Ho+{4f10(5I8)6s2}X- (X = F, Cl). Calculations of the ground state magnetic, h(X8), and quadrupole, eQq0(X8) hyperfine parameters from atomic hyperfine parameters are found to be consistent with the observed values for both molecules.

  12. HO x budgets in a deciduous forest: Results from the PROPHET summer 1998 campaign

    NASA Astrophysics Data System (ADS)

    Tan, D.; Faloona, I.; Simpas, J. B.; Brune, W.; Shepson, P. B.; Couch, T. L.; Sumner, A. L.; Carroll, M. A.; Thornberry, T.; Apel, E.; Riemer, D.; Stockwell, W.

    2001-10-01

    Results from a tightly constrained photochemical point model for OH and HO2 are compared to OH and HO2 data collected during the Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET) summer 1998 intensive campaign held in northern Michigan. The PROPHET campaign was located in a deciduous forest marked by relatively low NOx levels and high isoprene emissions. Detailed HOx budgets are presented. The model is generally unable to match the measured OH, with the observations 2.7 times greater than the model on average. The model HO2, however, is in good agreement with the measured HO2. Even with an additional postulated OH source from the ozonolysis of unmeasured terpenes, the measured OH is 1.5 times greater than the model; the model HO2 with this added source is 15% to 30% higher than the measured HO2. Moreover, the HO2/OH ratios as modeled are 2.5 to 4 times higher than the measured ratios, indicating that the cycling between OH and HO2 is poorly described by the model. We discuss possible reasons for the discrepancies.

  13. 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.

    2016-03-01

    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

  14. 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.

  15. 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.

  16. {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.

  17. Neutron Emission Spectra from Inelastic Scattering on 58,60Ni with a White Neutron Source at FIGARO

    SciTech Connect

    Rochman, D.; Haight, R.C.; O'Donnell, J. M.; Devlin, M.; Ethvignot, T.; Granier, T.; Grimes, S.M.; Talou, P.

    2005-05-24

    Neutron emission spectra from inelastic neutron scattering on natural nickel at the FIGARO facility have been measured by a double time-of-flight technique. The incident neutrons are produced from the spallation source of the Weapons Neutron Research facility, and their energies are determined by time of flight. The emitted neutrons and gamma rays are detected by 16 liquid scintillators and one high-resolution germanium or one barium-fluoride detector, respectively. The results for incident neutron energies from 2 to 10 MeV are compared with predictions of nuclear model calculations performed with the code EMPIRE-II. Finally, the level density parameters 'a' and ''{delta}'' are extracted.

  18. Magnetic excitations in tetragonal HoCr{sub 2}Si{sub 2}

    SciTech Connect

    Moze, O.; Osborn, R.; Buschow, K. H. J.

    2000-05-01

    Magnetic excitations in tetragonal HoCr{sub 2}Si{sub 2} have been measured by neutron spectroscopy. The temperature and Q dependence of the excitations measured at 8 K confirm that they can be attributed to crystal field (CF) dipolar transitions experienced by the Ho ion. The analysis of the neutron spectroscopy data for HoCr{sub 2}Si{sub 2} is simplified by the fact that the CF coefficients have already been determined for the series RX{sub 2}Si{sub 2} (R=rare earth, X=Cu, Ni) by neutron spectroscopy. In addition, electronic band structure calculations and experimental determinations of the electric field gradient for numerous compounds of the type RT{sub 2}Si{sub 2} (T=Cr, Cu, Ni) show that the first-order CF coefficient, A{sub 2}{sup 0}, changes sign when passing from the series RX{sub 2}Si{sub 2} (X=Cr, Ni) to RCu{sub 2}Si{sub 2}. In the light of this information, the available neutron spectroscopy data for HoCr{sub 2}Si{sub 2} are presented and discussed. (c) 2000 American Institute of Physics.

  19. Neutron Emission Spectra from Inelastic Scattering on 58,60Ni with a White Neutron Source at FIGARO.

    SciTech Connect

    Rochman, D.; O'Donnell, J. M.; Devlin, M. J.; Ethvignot, T.; Granier, T.; Grimes, S. M.

    2005-01-01

    Neutron emission spectra from inelastic neutron scattering on natural nickel at the FIGARO facility have been measured by a double time-of-flight technique. The incident neutrons are produced from the spallation source of the Weapons Neutron Research facility, and their energies are determined by time of flight. The emitted neutrons and gamma rays are detected by 16 liquid scintillators and one high-resolution germanium or one barium-fluoride detector, respectively. The results for incident neutron energies from 2 to 10 MeV are compared with predictions of nuclear model calculations performed with the code EMPIRE-II. Finally, the level density parameters 'a' and '{Delta}E' are extracted.

  20. 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.

  1. 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.

  2. Multivariate optimization of ultrasound-assisted extraction for determination of Cu, Fe, Ni and Zn in vegetable oils by high-resolution continuum source atomic absorption spectrometry.

    PubMed

    Trindade, Alex S N; Dantas, Alailson F; Lima, Daniel C; Ferreira, Sérgio L C; Teixeira, Leonardo S G

    2015-10-15

    An assisted liquid-liquid extraction of copper, iron, nickel and zinc from vegetable oil samples with subsequent determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was optimized by applying a full factorial design in two levels and the response surface methodology, Box-Behnken. The effects of the acid concentration and the amplitude, cycle and time of sonication on the extraction of the analytes, as well as their interactions, were assessed. In the selected condition (sonication amplitude = 66%, sonication time = 79 s, sonication cycle = 74%), using 0.5 mol L(-1) HCl as the extractant, the limits of quantification were 0.14, 0.20, 0.21 and 0.04 μg g(-1) for Cu, Fe, Ni and Zn, respectively, with R.S.D. ranging from 1.4% to 3.6%. The proposed method was applied for the determination of the analytes in soybean, canola and sunflower oils. PMID:25952852

  3. 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.

  4. Infrared spectra of products of the reaction of H atoms with O2 trapped in solid neon: HO2, HO2(+), HOHOH(-), and H2O(HO).

    PubMed

    Jacox, Marilyn E; Thompson, Warren E

    2013-10-01

    When a Ne/O2 mixture is codeposited at 4.3 K with a Ne/H2 mixture that has been passed through a microwave discharge, the infrared spectrum of the resulting deposit includes prominent absorptions of the three vibrational fundamentals of HO2 and seven relatively weak absorptions in the infrared and near-infrared, only one of them previously reported, that can be assigned to overtones and combination bands of that product. Similar assignments are made for DO2. A new, broad absorption at 702.9 cm(-1) appears close to the gas-phase absorption of HOHOH(-) at 697 cm(-1). Isotopic substitution experiments support that assignment. Evidence is also presented for the stabilization of HOHO(-). Absorptions near the vibrational fundamentals of H2O and an absorption at 3472.4 cm(-1) grow on exposure of the deposit to radiation of wavelength shorter than 345 nm. These absorptions are assigned to the H2O(HO) complex, in agreement with the results of an earlier argon-matrix study. In both studies, photodestruction of HO2 molecules that have H2O trapped in a nearby site results in formation of the complex. Because the discharge through Ne/H2 supports ion production, photodetachment of the resulting HOHOH(-) is an additional source of the complex. Other absorptions may be contributed by the bending fundamental of HO2(+) and by a cation complex with H2. PMID:23215001

  5. 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.

  6. 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.

  7. Magnetocaloric effect in a cluster-glass system Ho5Pd2-xNix

    NASA Astrophysics Data System (ADS)

    Toyoizumi, Saori; Kitazawa, Hideaki; Morita, Kengo; Tamaki, Akira

    2016-02-01

    In order to investigate the effect of chemical pressure on the large magnetocaloric effect in Ho5 Pd2, we conducted X-ray diffraction, magnetization, and specific heat measurements on Ho5Pd2-xNix(0≤ x ≤ 1.0) rare-earth intermetallic compounds. The linear x dependence of the lattice constant a suggests that Ni is replaced with Pd in the case of Ho5Pd2-xNix (0 ≤ x ≤ 0.5). The spin-glass transition temperature Tg and paramagnetic Curie temperature θP indicate a weak oscillatory x dependence. However, the magnetic entropy change —ΔSm and the relative cooling power (RCP) are rapidly suppressed with increasing x. These large reductions in —ΔSm and RCP cannot be explained only in terms of normal Ruderman-Kittel- Kasuya-Yoshida (RKKY)-type indirect exchange interactions.

  8. 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…

  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. Delayed cutaneous wound closure in HO-2 deficient mice despite normal HO-1 expression

    PubMed Central

    Lundvig, Ditte M S; Scharstuhl, Alwin; Cremers, Niels A J; Pennings, Sebastiaan W C; te Paske, Jeroen; van Rheden, René; van Run-van Breda, Coby; Regan, Raymond F; Russel, Frans G M; Carels, Carine E; Maltha, Jaap C; Wagener, Frank A D T G

    2014-01-01

    Impaired wound healing can lead to scarring, and aesthetical and functional problems. The cytoprotective haem oxygenase (HO) enzymes degrade haem into iron, biliverdin and carbon monoxide. HO-1 deficient mice suffer from chronic inflammatory stress and delayed cutaneous wound healing, while corneal wound healing in HO-2 deficient mice is impaired with exorbitant inflammation and absence of HO-1 expression. This study addresses the role of HO-2 in cutaneous excisional wound healing using HO-2 knockout (KO) mice. Here, we show that HO-2 deficiency also delays cutaneous wound closure compared to WT controls. In addition, we detected reduced collagen deposition and vessel density in the wounds of HO-2 KO mice compared to WT controls. Surprisingly, wound closure in HO-2 KO mice was accompanied by an inflammatory response comparable to WT mice. HO-1 induction in HO-2 deficient skin was also similar to WT controls and may explain this protection against exaggerated cutaneous inflammation but not the delayed wound closure. Proliferation and myofibroblast differentiation were similar in both two genotypes. Next, we screened for candidate genes to explain the observed delayed wound closure, and detected delayed gene and protein expression profiles of the chemokine (C-X-C) ligand-11 (CXCL-11) in wounds of HO-2 KO mice. Abnormal regulation of CXCL-11 has been linked to delayed wound healing and disturbed angiogenesis. However, whether aberrant CXCL-11 expression in HO-2 KO mice is caused by or is causing delayed wound healing needs to be further investigated. PMID:25224969

  11. Polyborides with Th 2NiB 10-Type Structure: Synthesis, Crystal Structure, and Magnetic and Electrical Properties

    NASA Astrophysics Data System (ADS)

    Jeitschko, Wolfgang; Konrad, Thomas; Hartjes, Klaus; Lang, Arne; Hoffmann, Rolf-Dieter

    2000-10-01

    The new rare-earth nickel polyborides R2NiB10 (R=Y, Ce-Nd, Sm, Gd-Ho) were prepared by reacting cold-pressed pellets of the elemental components in an arc-melting furnace, followed by annealing in evacuated silica tubes. They crystallize with the orthorhombic Th2NiB10-type structure, which was refined from X-ray powder diffractometer data of Ce2NiB10 (a=565.4(1) pm, b=1125.8(2) pm, c=419.6(1) pm) and Nd2NiB10 (a=561.4(1) pm, b=1119.2(2) pm, c=417.7(1) pm). The magnetic properties of these polyborides and also of Th2CoB10 and Th2NiB10 were determined with a superconducting quantum interference magnetometer between 2 and 400 K with magnetic flux densities up to 5.5 T. Y2NiB10, Th2CoB10, and Th2NiB10 are Pauli paramagnetic. The others show Curie-Weiss behavior with magnetic moments corresponding to those of the free R3+ ions, with the exception of Ce2NiB10, where cerium has a mixed valence and Sm2NiB10 with the van Vleck paramagnetic Sm3+ ion. Antiferromagnetic order was observed for the compounds R2NiB10 (R=Pr, Nd, Sm, Gd-Ho) with Néel temperatures ranging between 8 K for Pr2NiB10 and 33 K for Gd2NiB10. Tb2NiB10, Dy2NiB10, and Ho2NiB10 are metamagnetic. Electrical resistivity measurements reflect the magnetic ordering temperatures and indicate metallic behavior for all compounds.

  12. 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.

  13. 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.

  14. Mafic mantle sources indicated by the olivine-spinifex basalt-ferropicrite lavas in the accreted Permian oceanic LIP fragments and Miocene low-Ni basalt and adakite lavas in central Japan

    NASA Astrophysics Data System (ADS)

    Ishiwatari, A.; Ichiyama, Y.; Yamazaki, R.; Katsuragi, T.; Tsuchihashi, H.

    2008-12-01

    Melting of mafic (eclogitic) rocks in the peridotite mantle diapir may be important to generate a large quantity of magma in a short period of time as required for the LIP basaltic magmatism (e.g. Takahashi et al. 1998; EPSL, 162, 63-). Ferropicritic rocks also occur in some LIPs, and Ichiyama et al. (2006; Lithos, 89, 47-) propose a non-peridotitic, Ti- and Fe-rich eclogitic source (recycled oceanic ferrogabbro?) entrained in the peridotitic LIP mantle plume for the origin of ferropicritic rocks, that occur with olivine-spinifex basalt (Ichiyama et al., 2007; Island Arc, 16, 493-) in a Permian LIP fragment that was captured in the Jurassic Tamba accretionary complex in central Japan. Although Ti-poor ferrokomatiitic magma might form through high- degree melting of a primitive chondritic mantle (25wt% MgO and 25wt% Fe+FeO), Ti- and HFSE-rich ferropicritic and meimechitic magmas can not form in this way. On the other hand, Miocene volcanic rocks distributed along the Japan Sea coast of central Japan also represent a product of large-scale arc magmatism that happened coeval to the spreading of the Japan Sea floor. The chemical and isotopic signatures of the magmas are consistent with the secular change of tectonic setting from continental arc (22- 20 Ma) to island arc (15-11 Ma) (Shuto et al. 2006; Lithos, 86, 1-). Some adakites have already been found from these Miocene volcanic rocks by Shuto"fs group, and mafic rock melting in either subducting slab or lower arc crust has been proposed. We have recently found a wide distribution of low-Ni basalt from Fukui City. The low-Ni basalt contains olivine phenocrysts which are one order of magnitude poorer in Ni (less than 0.02 wt% NiO at Fo87) than those in normal basalt (more than 0.2 wt% NiO at Fo87). The rock is also poor in bulk-rock Ni, rich in K and Ti, and may have formed from an olivine-free pyroxenitic source. Close association of adakite and low-Ni basalt with normal tholeiitic basalt, calc-alkaline andesite

  15. 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.

  16. Ductility enhancement from interface dislocation sources in a directionally solidified beta + gamma + gamma-prime Ni-Fe-Al composite alloy

    NASA Technical Reports Server (NTRS)

    Larsen, M.; Misra, A.; Hartfield-Wunsch, S.; Noebe, R.; Gibala, R.

    1990-01-01

    A directionally solidified beta + gamma + gamma-prime Ni-Fe-Al in situ composite alloy of composition Ni50Fe30Al20 has been used to investigate the effect of a plastically soft second phase on the mechanical behavior of a B2 ordered intermetallic alloy. This material exhibits extensive plasticity during compressive deformation at room temperature and fails in shear with extensive gamma + gamma-prime lamellar or rod pullout. The material also exhibits about 10 percent tensile elongation to fracture at room temperature, with final fracture that includes substantial necking of the gamma + gamma-prime lamellae or rods. Observation of slip lines and dislocation substructures discloses that the normally brittle beta matrix undergoes extensive plasticity in order to deform compatibly with the more ductile gamma phase. The plasticity of the beta matrix is accomplished by the generation of glissile dislocations into the beta matrix from the beta/gamma interface region and is enhanced because of a favorable beta-gamma orientation relationship for slip transfer. Ductility enhancement from interface-generated mobile dislocations generated from beta-gamma interfaces is compared to that observed in film-coated beta-NiAl single crystals and FeAl polycrystals.

  17. High-energy multi-kilohertz Ho-doped regenerative amplifiers around 2 µm.

    PubMed

    von Grafenstein, Lorenz; Bock, Martin; Griebner, Uwe; Elsaesser, Thomas

    2015-06-01

    We report a high-gain, cw-pumped regenerative amplifier which is based on Ho-doped crystals and seeded by a versatile broadband source emitting between 2050 and 2100 nm. The regenerative amplifier is implemented in a chirped-pulse amplification system operating at room temperature. Using Ho:YLF as gain medium, 1.1 mJ pulses with a 50 ps pulse duration and a 10 kHz repetition rate are generated at 2050 and 2060 nm, corresponding to an average power of 11 W. Using the same seed source, a 10 kHz Ho:YAG regenerative amplifier at 2090 nm is studied in the same configuration. In all cases the regenerative amplifier parameters are chosen to operate in a tunable single-energy regime without instabilities. PMID:26072833

  18. HORUS Measurements of OH and HO2: Method and First Measurements During GABRIEL

    NASA Astrophysics Data System (ADS)

    Martinez, M.; Harder, H.; Kubistin, D.; Rudolf, M.; Bartenbach, S.; Bozem, H.; Butler, T.; Colomb, A.; Eerdekens, G.; Fischer, H.; Gebhardt, S.; Gurk, C.; Hofmann, R.; Klüpfel, T.; Königstedt, R.; Parchatka, U.; Schiller, C.; Stickler, A.; Williams, J.; Yassaa, N.; Lelieveld, J.

    2006-12-01

    OH and HO2 were measured for the first time over a tropical rain forest during the GABRIEL campaign in October 2005 with HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy), developed at the MPI for Chemistry and adapted to fly in a Learjet wingpod. The measurements show unexpectedly high mixing ratios for both OH and HO2 in the boundary layer over the rain forest. The impact of biogenic emissions on OH and HO2 mixing ratios and diurnal variability as the air is transported over the forest is discussed. The extensive dataset measured during GABRIEL including measurements of many other trace gases and photolysis frequencies allows quantification of the main sources and sinks of OH. Comparison of the derived formation and loss rates of OH indicates the existence of additional yet unidentified sources of OH over the tropical rain forest.

  19. Significance of HO x and peroxides production due to alkene ozonolysis during fall and winter: A modeling study

    NASA Astrophysics Data System (ADS)

    Ariya, Parisa A.; Sander, Rolf; Crutzen, Paul J.

    2000-07-01

    In an attempt to identify new mechanisms for the generation of oxidants during fall and winter, we carried out a modeling investigation in which ozonolysis reactions of alkenes that were primarily anthropogenic in origin were considered. Our results indicate that the ozonolysis reactions of these molecules can be the major sources of HOx, H2O2, and organic peroxides during the night and therefore especially during dark seasons. These O3-initiated oxidation reactions produce more peroxy radicals than those initiated by HO or NO3. This increase in RO2 also results in an increase in HO, HO2, and H2O2. The direct HO formation pathways by ozonolysis of alkenes can form more HO radicals than that from the reaction of O(1D) + H2O during the dark seasons. This additional source of HO can augment significantly atmospheric oxidation. H2O2 formation by ozonolysis also appears to be the most important dark season tropospheric sources of this oxidant. Our modeling results suggest that the existence of pollutant hydrocarbons and trace amount of biogenically produced terpenes can also lead to important production of HOx, H2O2, and organic peroxides. Substantially enhanced gas-phase production of H2O2 and organic peroxides due to ozonolysis reactions can cause significant liquid-phase oxidation of S(IV) to S(VI), and hence the role of ozonolysis reactions can be important for the sulfur conversion studies.

  20. 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...

  1. 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...

  2. Peroxynitric acid (HO2NO2) measurements during the UBWOS 2013 and 2014 studies using iodide ion chemical ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Veres, P. R.; Roberts, J. M.; Wild, R. J.; Edwards, P. M.; Brown, S. S.; Bates, T. S.; Quinn, P. K.; Johnson, J. E.; Zamora, R. J.; de Gouw, J.

    2015-07-01

    In this paper laboratory work is documented establishing iodide ion chemical ionization mass spectrometry (I- CIMS) as a sensitive method for the unambiguous detection of peroxynitric acid (HO2NO2; PNA). A dynamic calibration source for HO2NO2, HO2, and HONO was developed and calibrated using a novel total NOy cavity ring-down spectroscopy (CaRDS) detector. Photochemical sources of these species were used for the calibration and validation of the I- CIMS instrument for detection of HO2NO2. Ambient observations of HO2NO2 using I- CIMS during the 2013 and 2014 Uintah Basin Wintertime Ozone Study (UBWOS) are presented. Strong inversions leading to a build-up of many primary and secondary pollutants as well as low temperatures drove daytime HO2NO2 as high as 1.5 ppbv during the 2013 study. A comparison of HO2NO2 observations to mixing ratios predicted using a chemical box model describing an ozone formation event observed during the 2013 wintertime shows agreement in the daily maxima HO2NO2 mixing ratio, but a differences of several hours in the timing of the observed maxima. Observations of vertical gradients suggest that the ground snow surface potentially serves as both a net sink and source of HO2NO2 depending on the time of day. Sensitivity tests using a chemical box model indicate that the lifetime of HO2NO2 with respect to deposition has a non-negligible impact on ozone production rates on the order of 10 %.

  3. 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.

  4. Presence of an HO-1 expression threshold in renal glomeruli.

    PubMed

    Detsika, Maria G; Atsaves, Vassileios; Papalois, Apostolos; Lianos, Elias A

    2015-12-01

    This article reports data describing HO-1 expression patterns of heme oxygenase (HO)-1 in isolated rat glomeruli and in cultured glomerular epithelial cells (GEC) in response to its natural substrate heme. Qualitative and quantitative data are presented to support presence of a HO-1 expression threshold in glomeruli but not in GEC. Interpretation of our data and further insight into HO-1 expression pattern in glomeruli may be found in 'HO-1 expression control in the rat glomerulus' [1]. PMID:26702422

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

    PubMed

    Sprague, Matthew K; Irikura, Karl K

    2015-07-01

    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. PMID:26066551

  6. 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.

  7. Swift observations of ASASSN-15ni

    NASA Astrophysics Data System (ADS)

    Campana, S.

    2015-07-01

    Swift observed ASASSN-15ni (Dong et al. 2015, Atel #7850) starting on 2015-07-29 01:13:07.00 UT for 2.0 ks. The XRT detected one source coincident with the optical position of ASASSN-15ni at a rate of (1.4+/-0.3) x 10^-2 counts s^-1.

  8. Monte Carlo simulation of liver cancer treatment with 166Ho-loaded glass microspheres

    NASA Astrophysics Data System (ADS)

    da Costa Guimarães, Carla; Moralles, Maurício; Roberto Martinelli, José

    2014-02-01

    Microspheres loaded with pure beta-emitter radioisotopes are used in the treatment of some types of liver cancer. The Instituto de Pesquisas Energéticas e Nucleares (IPEN) is developing 166Ho-loaded glass microspheres as an alternative to the commercially available 90Y microspheres. This work describes the implementation of a Monte Carlo code to simulate both the irradiation effects and the imaging of 166Ho and 90Y sources localized in different parts of the liver. Results obtained with the code and perspectives for the future are discussed.

  9. Formation of dioxins on NiO and NiCl2 at different oxygen concentrations.

    PubMed

    Yang, Jie; Yan, Mi; Li, Xiaodong; Lu, Shengyong; Chen, Tong; Yan, Jianhua; Olie, Kees; Buekens, Alfons

    2015-08-01

    Model fly ash (MFA) containing activated carbon (AC) as source of carbon, NaCl as source of chlorine and either NiO or NiCl2 as de novo catalyst, was heated for 1h at 350 °C in a carrier gas flow composed of N2 containing 0, 6, 10, and 21 vol.% O2, to study the formation of PCDD/Fs (dioxins) and its dependence on oxygen. The formation of PCDD/Fs with NiCl2 was stronger by about two orders of magnitude than with NiO and the difference augmented with rising oxygen concentration. The thermodynamics of the NiO-NiCl2 system were represented, X-ray absorption near edge structural (XANES) spectroscopy allowed to probe the state of oxidation of the nickel catalyst in the MFA and individual metal species were distinguished using the LCF (Linear combination fitting) technique: thus three supplemental nickel compounds (Ni2O3, Ni(OH)2, and Ni) were found in the fly ash. Principal Component Analysis (PCA) indicates that both Ni2O3 and NiCl2 probably played an important role in the formation of PCDD/Fs. PMID:25951618

  10. 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.

  11. Ultrafast Alkaline Ni/Zn Battery Based on Ni-Foam-Supported Ni3S2 Nanosheets.

    PubMed

    Hu, Pu; Wang, Tianshi; Zhao, Jingwen; Zhang, Chuanjian; Ma, Jun; Du, Huiping; Wang, Xiaogang; Cui, Guanglei

    2015-12-01

    Self-supported Ni3S2 ultrathin nanosheets were in situ formed by direct sulfurization of commercially available nickel foam using thioacetamide as sulfur source under hydrothermal process. The morphology and structure of the as-obtained sample were analyzed by using XRD, XPS, SEM, and TEM, revealing that an ultrathin nanosheets Ni3S2 were grown on the surface of Ni form. The as-obtained Ni3S2/Ni composite with uniform architecture was used as cathode material for alkaline Ni/Zn battery, which delivered high capacity of 125 mAh g(-1) after 100 cycles with no obvious capacity fading, extraordinary rate capability (68 mAh g(-1) at the current density of 5.0 A g(-1)), and high operating voltage (1.75 V). PMID:26599523

  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. PMID:19997290

  13. Magnetic structures in RNi{sub 2}B{sub 2}C (R = Ho, Er) superconductors

    SciTech Connect

    Stassis, C.; Goldman, A.I.; Dervenagas, P.; Zarestky, J.; Canfield, P.C.; Cho, B.K.; Johnston, D.C.; Sternlieb, B.; Sternlieb, B.

    1994-12-31

    Single crystal neutron diffraction techniques have been employed to study the evolution of magnetic structures in RNi{sub 2}B{sub 2}C compounds in an attempt to understand the relationship between magnetic ordering and superconductivity in several members of this series. For HoNi{sub 2}B{sub 2}C, below the superconducting transition (T{sub c} = 8 K), an incommensurate magnetic structure characterized by two wave vectors (0.585 a* and 0.915 c*) is found in a narrow temperature range between 4.7 K and 6 K. This is the same temperature range where bulk measurements find a deep minimum in the upper critical field, H{sub c2}. Below 4.7 K, HoNi{sub 2}B{sub 2}C is a simple collinear antiferromagnet. ErNi{sub 2}B{sub 2}C ({Tc} = 11 K) orders in an incommensurate modulated antiferromagnetic state characterized by an ordering wave vector 0.553 a* below 7 K, which coexists with superconductivity.

  14. 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.

  15. Energy levels of HoBr 63-

    NASA Astrophysics Data System (ADS)

    Tanner, Peter A.

    1986-12-01

    The excitation, electronic absorption and luminescence spectra of cubic Cs 2NaHoBr 6 have been recorded at temperatures down to that of liquid helium. The detailed spectral analyses enable comparisons to be made of the crystal-field splittings of Russell—Saunders terms with those in Cs 2NaHoCl 6. Under intense 647.1 nm laser excitation, luminescence is observed in the neat material in the spectral region between 17800 and 21750 cm -1.

  16. Electron-impact excitation of H-like Cr, Mn, Fe, Co, and Ni for applications in modeling X-ray astrophysical sources

    NASA Astrophysics Data System (ADS)

    Malespin, C.; Ballance, C. P.; Pindzola, M. S.; Witthoeft, M. C.; Kallman, T. R.; Loch, S. D.

    2011-02-01

    Context. Accurate atomic data for the less abundance Fe-peak elements are required for use in X-ray astrophysical studies. Aims: We calculate high quality electron-impact excitation collision strengths and effective collision strengths for hydrogenic Cr, Mn, Fe, Co, and Ni. Methods: We use the Dirac R-matrix method, the intermediate coupling frame transformation R-matrix method, the semi-relativistic distorted-wave method and the fully-relativistic distorted-wave method to calculate collision strengths for each of the ions. The ADAS collisional-radiative codes are used to produce photon emissivity coefficients for each ion. Results: Results are presented for atomic energy levels, spontaneous emission coefficients, electron-impact excitation collision strengths and associated effective collision strengths for each of the five species under consideration. We find relativistic effects can contribute an approximate 10% increase to the background cross section in relation to semi-relativistic collision calculations. We also confirm that radiation damping plays a prominent role for certain near threshold resonances. In order check the integration of our results within collisional-radiative modeling codes, we have used the ADAS package for some preliminary modeling of photon emissivities. The atomic data shall be made available online through the OPEN-ADAS site and the CFADC database Final datasets for each ion are only available in electronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A115

  17. 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...

  18. 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.

  19. 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

  20. Modeling global impacts of heterogeneous loss of HO2 on cloud droplets, ice particles and aerosols

    NASA Astrophysics Data System (ADS)

    Huijnen, V.; Williams, J. E.; Flemming, J.

    2014-03-01

    The abundance and spatial variability of the hydroperoxyl radical (HO2) in the troposphere strongly affects atmospheric composition through tropospheric ozone production and associated HOx chemistry. One of the largest uncertainties in the chemical HO2 budget is its heterogeneous loss on the surface of cloud droplets, ice particles and aerosols. We quantify the importance of the heterogeneous HO2 loss at global scale using the latest recommendations on the scavenging efficiency on various surfaces. For this we included the simultaneous loss on cloud droplets and ice particles as well as aerosol in the Composition-Integrated Forecast System (C-IFS). We show that cloud surface area density (SAD) is typically an order of magnitude larger than aerosol SAD, using assimilated satellite retrievals to constrain both meteorology and global aerosol distributions. Depending on the assumed uptake coefficients, loss on liquid water droplets and ice particles accounts for ∼53-70% of the total heterogeneous loss of HO2, due to the ubiquitous presence of cloud droplets. This indicates that HO2 uptake on cloud should be included in chemistry transport models that already include uptake on aerosol. Our simulations suggest that the zonal mean mixing ratios of HO2 are reduced by ∼25% in the tropics and up to ∼50% elsewhere. The subsequent decrease in oxidative capacity leads to a global increase of the tropospheric carbon monoxide (CO) burden of up to 7%, and an increase in the ozone tropospheric lifetime of ∼6%. This increase results in an improvement in the global distribution when compared against CO surface observations over the Northern Hemisphere, although it does not fully resolve the wintertime bias in the C-IFS. There is a simultaneous increase in the high bias in C-IFS for tropospheric CO over the Southern Hemisphere, which constrains on the assumptions regarding HO2 uptake on a global scale. We show that enhanced HO2 uptake on aerosol types associated with

  1. Pressure Dependent OH and HO2 Calibration of the Fluorescence Assay by Gas Expansion (FAGE) Instrument Using the Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC)

    NASA Astrophysics Data System (ADS)

    Winiberg, F.; Smith, S. C.; Seakins, P.

    2012-12-01

    The hydroxyl (OH) and hydroperoxy (HO2) radical are very important tropospheric radical species. The balance between OH and HO2 (the HOx cycle) can give understanding of localised atmospheric composition. OH and HO2 is measured in both ground and aircraft based campaigns using FAGE. Calibration of this non-absolute fluorescence technique is traditionally achieved by H2O photolysis. Operation of FAGE at varying pressure can affect the instrument sensitivity to HOx due to internal fluorescence cell pressure changes. These are traditionally accounted by varying the inlet pinhole size of the instrument, however this may alter the gas expansion and hence the instrument sensitivity to OH and HO2 (COH and CHO2 respectively). Presented here are the initial results from independent OH and HO2 pressure dependent calibration methods using the stainless steel HIRAC chamber, which can operate at various pressures (0.1 - 1 bar). The OH calibration method uses the loss rate of a well characterised hydrocarbon upon reaction with OH to infer the OH concentration measured by FAGE in the HIRAC chamber. A photolytic OH source ((CH3)3COOH) was used and all reactants were measured using calibrated GC-FID and FTIR. For HO2 calibrations, formaldehyde, HCHO, is photolysed (λ < 300 nm) in the presence of O2 to form 2HO2 to steady state, and the post-photolysis HO2 decay is monitored using FAGE. The decay is a function of the second order HO2 self-reaction, for which the rate is well known. As [HO2] = SHO2 x CHO2 (where SHO2 is the FAGE HO2 signal), the second order rate equation can be rearranged and a plot of 1/SHO2 vs. time yields CHO2. Preliminary experiments for the OH calibration method show discrepancies between traditional and hydrocarbon decay techniques. This is thought to be due to as yet unknown OH loss processes and conditioning of the HIRAC chamber. For the HO2 pressure dependent calibrations were in good agreement with traditional methods validating the widely used

  2. DFT study of the water gas shift reaction on Ni(111), Ni(100) and Ni(110) surfaces

    NASA Astrophysics Data System (ADS)

    Mohsenzadeh, Abas; Richards, Tobias; Bolton, Kim

    2016-02-01

    Density functional theory (DFT) calculations were used to study the water gas shift (WGS) reaction on Ni(111), Ni(100) and Ni(110) surfaces. The adsorption energy for ten species involved in the reaction together with activation barriers and reaction energies for the nine most important elementary steps were determined using the same model and DFT methods. The results reveal that these energies are sensitive to the surface structure. In spite of this, the WGS reaction occurs mainly via the direct (also referred to as redox) pathway with the CO + O → CO2 reaction as the rate determining step on all three surfaces. The activation barrier obtained for this rate limiting step decreases in the order Ni(110) > Ni(111) > Ni(100). Therefore, if O species are present on the surfaces then the WGS reaction is fastest on the Ni(100) surface. However, the barrier for desorption of H2O (which is the source of the O species) is lower than its dissociation reaction on the Ni(111) and Ni(100) surfaces, but not on the Ni(110) surface. Hence, at low H2O(g) pressures, the direct pathway on the Ni(110) surface will dominate and will be the rate limiting step. The calculations also show that the reason that the WGS reaction does not primarily occur via the formate pathway is that this species is a stable intermediate on all surfaces. The reactions studied here support the Brønsted-Evans-Polanyi (BEP) principles with an R2 value of 0.99.

  3. Presence of an HO-1 expression threshold in renal glomeruli

    PubMed Central

    Detsika, Maria G; Atsaves, Vassileios; Papalois, Apostolos; Lianos, Elias A.

    2015-01-01

    This article reports data describing HO-1 expression patterns of heme oxygenase (HO)-1 in isolated rat glomeruli and in cultured glomerular epithelial cells (GEC) in response to its natural substrate heme. Qualitative and quantitative data are presented to support presence of a HO-1 expression threshold in glomeruli but not in GEC. Interpretation of our data and further insight into HO-1 expression pattern in glomeruli may be found in ‘HO-1 expression control in the rat glomerulus’ [1]. PMID:26702422

  4. OH and HO2 Concentrations during PROPHET 2008: Measurement and Theory

    NASA Astrophysics Data System (ADS)

    Griffith, S. M.; Hansen, R. F.; Dusanter, S.; Stevens, P. S.; Galloway, M. M.; Hottle, J.; Kammrath, A.; Keutsch, F.; Mielke, L. H.; Alaghmand, M.; Shepson, P. B.; Zhang, N.; Zhou, X.; Bertman, S. B.; Carroll, M.

    2009-12-01

    Hydroxyl (OH) and hydroperoxy (HO2) radicals are key species driving the gas-phase oxidation of organic trace gases that lead to the formation of ozone and secondary organic aerosols in the troposphere. Previous measurements of OH and HO2 radicals in forest environments have shown serious discrepancies with modeled concentrations of these radicals. These discrepancies bring into question our understanding of the atmospheric chemistry of isoprene and other reactive biogenic emissions. During the summer of 2008, OH and HO2 (HOx) radical measurements were made at the forested PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions, and Transport) site in northern Michigan using a laser-induced fluorescence instrument developed at Indiana University. A suite of additional measurements including isoprene, methyl vinyl ketone, methacrolein, total monoterpenes, glyoxal, formaldehyde, nitrogen oxides (NOx), ozone, and UV actinic flux were measured simultaneously. These measurements were used to constrain a zero-dimensional model based on the Regional Atmospheric Chemistry Mechanism to predict the expected HOx radical concentrations. This analysis investigates individual day and night measured and modeled HOx concentrations, the HO2/OH ratio, and the production and loss processes governing HOx in this remote forested environment. Included in this analysis are 1) efforts to characterize the ozonolysis of unquantified highly reactive terpenes, which may be a potentially significant unaccounted for source of radicals in forested environments, and 2) the impact of recently proposed OH recycling in the isoprene oxidation mechanism that could lead to higher sustained OH concentrations.

  5. 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.

  6. 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...

  7. 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

  8. 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.

  9. HO-1/CO system in tumor growth, angiogenesis and metabolism - Targeting HO-1 as an anti-tumor therapy.

    PubMed

    Loboda, Agnieszka; Jozkowicz, Alicja; Dulak, Jozef

    2015-11-01

    Heme oxygenase-1 (HO-1, hmox-1) catalyzes the rate-limiting step in the heme degradation processes. Out of three by-products of HO-1 activity, biliverdin, iron ions and carbon monoxide (CO), the latter was mostly shown to mediate many beneficial HO-1 effects, including protection against oxidative injury, regulation of apoptosis, modulation of inflammation as well as contribution to angiogenesis. Mounting evidence suggests that HO-1/CO systemmay be of special benefit in protection inmany pathological conditions, like atherosclerosis or myocardial infarction. By contrast, the augmented expression of HO-1 in tumor tissues may have detrimental effect as HO-1 accelerates the formation of tumor neovasculature and provides the selective advantage for tumor cells to overcome the increased oxidative stress during tumorigenesis and during treatment. The inhibition of HO-1 has been proposed as an anti-cancer therapy, however, because of non-specific effects of known HO-1 inhibitors, the discovery of ideal drug lowering HO-1 expression/activity is still an open question. Importantly, in several types of cancer HO-1/CO system exerts opposite activities, making the possible treatment more complicated. All together indicates the complex role for HO-1/CO in various in vitro and in vivo conditions. PMID:26392237

  10. Preparatory studies for a high-precision Penning-trap measurement of the 163Ho electron capture Q-value

    NASA Astrophysics Data System (ADS)

    Schneider, F.; Beyer, T.; Blaum, K.; Block, M.; Chenmarev, S.; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Eibach, M.; Eliseev, S.; Grund, J.; Köster, U.; Nagy, Sz.; Novikov, Yu. N.; Renisch, D.; Türler, A.; Wendt, K.

    2015-07-01

    The ECHo Collaboration (Electron Capture 163Ho aims to investigate the calorimetric spectrum following the electron capture decay of 163Ho to determine the mass of the electron neutrino. The size of the neutrino mass is reflected in the endpoint region of the spectrum, i.e., the last few eV below the transition energy. To check for systematic uncertainties, an independent determination of this transition energy, the Q-value, is mandatory. Using the TRIGA-TRAP setup, we demonstrate the feasibility of performing this measurement by Penning-trap mass spectrometry. With the currently available, purified 163Ho sample and an improved laser ablation mini-RFQ ion source, we were able to perform direct mass measurements of 163Ho and 163Dy with a sample size of less than 1017 atoms. The measurements were carried out by determining the ratio of the cyclotron frequencies of the two isotopes to those of carbon cluster ions using the time-of-flight ion cyclotron resonance method. The obtained mass excess values are ME(163Ho)= -66379.3(9) keV and ME(163Dy)= -66381.7(8) keV. In addition, the Q-value was measured for the first time by Penning-trap mass spectrometry to be Q = 2.5(7) keV.

  11. Measurement of free radicals OH and HO2 in Los Angeles smog

    NASA Astrophysics Data System (ADS)

    George, L. A.; Hard, T. M.; O'Brien, R. J.

    1999-05-01

    Atmospheric free radicals hydroxyl and hydroperoxyl (OH and HO2, collectively HOx) are the catalysts that cause secondary or photochemical air pollution. Chemical mechanisms for oxidant and acid formation, on which expensive air pollution control strategies are based, must accurately predict these radical concentrations. We have used the fluorescence assay with gas expansion (FAGE) technique to carry out the first simultaneous, in situ measurements of these two radicals in highly polluted air during the Los Angeles Free Radical Experiment. A complete suite of ancillary measurements was also made, including speciated hydrocarbons, carbon monoxide, aldehydes, nitric oxide, nitrogen dioxide, and ozone along with meteorological parameters. Using this suite of measurements, we tested the ability of a lumped chemical mechanism to accurately predict radical concentrations in polluted air. Comparison of model predictions with measured radical concentrations revealed generally good agreement for OH early and late in the day, including the early evening hours, when OH persisted at low concentrations after dark. During midday, however, modeled [OH] was high by about 50%. Agreement for HO2 was quite good in the early morning hours, but model-calculated HO2 concentrations were significantly too high during midday. When we used our measured HO2 concentrations as model input, agreement between calculated and measured OH concentrations was improved. It seems likely that (1) the model's HOx sources are too large, (2) there are unaccounted HOx loss processes in Los Angeles air, and/or (3) the complex parameterization of RO2/HO2 radical chemistry in the reaction mechanism does not adequately describe the behavior of these radicals in the Los Angeles atmosphere.

  12. One-step grown multi-walled carbon nanotubes with Ni filling and decoration

    NASA Astrophysics Data System (ADS)

    Baro, Mahananda; Pal, Arup R.

    2015-06-01

    A single step approach for the synthesis of multi-walled carbon nanotubes filled with Ni nanowires (Ni-MWCNTs) and decorated with Ni nanoparticles has been illustrated. The MWCNTs are grown by a PECVD-sputtering hybrid process at the low temperature of 450 °C having an average diameter of 55   ±   6 nm and length of 1.35   ±   0.08 µm. Thin Ni films of the thickness 10 nm have been used, which act as a catalyst as well as a source material for the filling of MWCNTs with Ni nanowires, whereas sputtering of Ni is the source of decorated Ni particles. This process facilitates the growth of aligned MWCNTs filled with Ni nanowires and also decorated with Ni nanoparticles on the walls. Magnetic properties of the Ni filled and decorated MWCNTs are measured using a vibrating sample magnetometer. Magnetic hysteresis loops of Ni containing MWCNTs show ferromagnetic behavior. These Ni-MWCNTs shows coercivity of 135 Oe, which is significantly greater than that of the bulk Ni at room temperature. The magnetic property measurement reveals that the coercivity of the as grown MWCNTs is dependent on the size and content of Ni. Thus, a novel method has been demonstrated for the synthesis of ferromagnetic Ni-MWCNT which has potential applications in various fields.

  13. 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.

  14. U(1) Invariant F(tilde{R}) Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Klusoň, J.; Nojiri, S.; Odintsov, S. D.; Sáez-Gómez, D.

    2011-07-01

    This paper is devoted to the study of various aspects of projectable F( R) Hořava-Lifshitz (HL) gravity. We show that some versions of F( R) HL gravity may have stable de Sitter solution and unstable flat-space solution. In this case, the problem of scalar graviton does not appear because flat space is not vacuum state. Generalizing the U(1) HL theory proposed in Source>arXiv:1007.2410Source> , we formulate U(1) extension of scalar theory and of F( R) Hořava-Lifshitz gravity. The Hamiltonian approach for such the theory is developed in full detail. It is demonstrated that its Hamiltonian structure is the same as for the non-relativistic covariant HL gravity. The spectrum analysis performed around the flat background indicates the consistency of the theory because it contains a graviton with only transverse polarization. Finally, we analyze the spatially flat FRW equations for U(1) invariant F( R) Hořava-Lifshitz gravity.

  15. Rotational bands in neutron-rich 160-162Ho

    SciTech Connect

    Escrig, D.; Jungclaus, A.; Binder, B.; Dietrich, A.; Haertlein, T.; Bauer, H.; Gund, Ch.; Pansegrau, D.; Schwalm, D.; Bazzacco, D.; De Angelis, G.; Farnea, E.; Gadea, A.; Lunardi, S.; Napoli, D.R.; Rossi-Alvarez, C.; Ur, C.

    2004-02-27

    We have studied the high spin states in 160-162Ho in order to investigate the properties of the rotational bands and their dependence on the single particle orbits involved. The reaction 158,160Gd(7Li,xn) at 56 MeV were used to produce the Ho isotopes of interest. In all three Ho isotopes the known rotational bands have been significantly extended. New band-crossings have been observed for the first time in this work.

  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. A tunable and single-longitudinal-mode Ho:YLF laser

    NASA Astrophysics Data System (ADS)

    Dai, T. Y.; Wu, J.; Ju, L.; Zhang, Z. G.; Xu, L. W.; Yao, B. Q.; Wang, Y. Z.

    2016-07-01

    A 1.94 μm Tm-doped fiber laser pumped tunable single-longitudinal-mode Ho:YLF laser with double etalons was reported for the first time. The maximum single-longitudinal-mode output power of 345 mW at 2051.6 nm was achieved at the absorbed pump power of 11.9 W, corresponding to a slope efficiency of 5.5% and an optical conversion efficiency of 2.9%. By regulating the angle of the F-P etalons, the output wavelength of the laser can be tuned from 2051.6 nm to 2063.3 nm. The single-longitude-mode Ho:YLF laser operating at 2 μm can be used as the seed laser source of coherent Doppler lidar, differential absorption lidar and so on.

  18. Comparison of in-band pumped Tm:fiber and Ho:fiber

    NASA Astrophysics Data System (ADS)

    Sincore, Alex; Shah, Lawrence; Smirnov, Vadim; Richardson, Martin

    2016-03-01

    Thulium and holmium have become the rare earth dopants of choice for generating 2 micron laser light in silica fiber. The majority of Tm:fiber lasers are pumped with high power diodes at 790nm and rely upon cross-relaxation processes to achieve optical-to-optical efficiencies of 55-65%. Tm:fiber lasers can also be pumped at <1900nm by another Tm:fiber laser to minimize quantum defect, reaching efficiencies >90%. Ho:fiber lasers are similarly pumped by Tm:fiber lasers at 1900-1950nm, with <70% typical efficiency. In this work, Tm:fiber and Ho:fiber lasers are in-band pumped using the same experimental setup to directly compare their performance as 2 micron sources.

  19. Efficient, low threshold, cryogenic Ho:YAG laser.

    PubMed

    Ganija, Miftar; Simakov, Nikita; Hemming, Alexander; Haub, John; Veitch, Peter; Munch, Jesper

    2016-05-30

    We report the development of an efficient, liquid-nitrogen conduction cooled Ho:YAG slab laser with good beam quality. Detailed measurements resolving the structure of the 1900-1911 nm absorption band in Ho:YAG at 77 K are presented. Stress-free conduction cooled mounting of the Ho:YAG slab was demonstrated and the resulting laser operated with a large mode volume of 42 mm3, a slope efficiency of 75% and a threshold of 0.84 W. To our knowledge this corresponds to the lowest reported threshold intensity for a Ho:YAG laser. PMID:27410084

  20. 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.

  1. 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.

  2. Hořava-Lifshitz quantum cosmology

    NASA Astrophysics Data System (ADS)

    Bertolami, Orfeu; Zarro, Carlos A. D.

    2011-08-01

    In this work, a minisuperspace model for the projectable Hořava-Lifshitz gravity without the detailed-balance condition is investigated. The Wheeler-DeWitt equation is derived and its solutions are studied and discussed for some particular cases where, due to Hořava-Lifshitz gravity, there is a “potential barrier” nearby a=0. For a vanishing cosmological constant, a normalizable wave function of the Universe is found. When the cosmological constant is nonvanishing, the WKB method is used to obtain solutions for the wave function of the Universe. Using the Hamilton-Jacobi equation, one discusses how the transition from quantum to classical regime occurs and, for the case of a positive cosmological constant, the scale factor is shown to grow exponentially, hence recovering the general relativity behavior for the late Universe.

  3. Ho Doped BixSby Nanopolycrystalline Alloys

    NASA Astrophysics Data System (ADS)

    Lukas, K. C.; Joshi, G.; Wang, Dezhi; Ren, Z. F.; Opeil, C. P.

    2011-03-01

    Department of Physics, Boston College, Chestnut Hill, Massachusetts, 02467. Bismuth-Antimony alloys have been shown to have high ZT values below room temperature, especially for single crystals. For polycrystalline samples, impurity doping and magnetic field have proven to be powerful tools in the search for understanding and improving thermoelectric performance. Nanopolycrystalline BixSby doped with 1 and 3 % Ho were prepared by ball milling and dc hot pressing technique. Electrical resistivity, Seebeck coefficient, thermal conductivity, carrier concentration, mobility, and magnetization are measured in a temperature range of 5-350 K and in magnetic fields up to 9 Tesla. The effects of Ho doping on the thermoelectric properties of BixSby in magnetic field will be discussed. D.O.E. Energy Frontier Research Center Grant (S3TEC), at Massachusetts Institute of Technology.

  4. 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.

  5. Ni(II) salts and 2-propanol effect catalytic reductive coupling of epoxides and alkynes.

    PubMed

    Beaver, Matthew G; Jamison, Timothy F

    2011-08-01

    A Ni-catalyzed reductive coupling of alkynes and epoxides using Ni(II) salts and simple alcohol reducing agents is described. Whereas previously reported conditions relied on Ni(cod)(2) and Et(3)B, this system has several advantages including the use of air-stable and inexpensive Ni(II) precatalysts (e.g., NiBr(2)·3H(2)O) as the source of Ni(0) and simple alcohols (e.g., 2-propanol) as the reducing agent. Deuterium-labeling experiments are consistent with oxidative addition of an epoxide C-O bond that occurs with inversion of configuration. PMID:21718038

  6. 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.

  7. 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.

  8. 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.

  9. Magnetism and superconductivity in (HoxY1-x)Ni2B2C

    NASA Astrophysics Data System (ADS)

    Müller, Karl-Hartmut; Fuchs, Günter; Handstein, Axel; Cao, Lei; Eversmann, Kathrin

    1996-02-01

    The pseudoquarternary system (HoxY1-x)Ni2B2C, has been investigated by resistance and magnetization measurements. A linear depression of the superconducting transition temperature Tc found with increasing Ho content is interpreted in the framework of the Abrikosov-Gor'kov theory which predicts also a linear scaling of Tc with the de Gennes factor of the rare earth elements R of the RNi2B2C family. We found that both cases follow a common linear scaling behaviour including the superconducting transition and the magnetic ordering temperature. A reentrant behaviour observed for Ho contents x≥0.5 results in maxima in the temperature dependence of the upper critical field Hc2(T), which are compared with Hc2(T) data of TmNi2B2C. In the paramagnetic range of field and temperature the sample magnetization can be described by a Brillouin function with a Ho-moment of 10.5 μ B.

  10. Hořava-Lifshitz gravity and effective theory of the fractional quantum Hall effect

    NASA Astrophysics Data System (ADS)

    Wu, Chaolun; Wu, Shao-Feng

    2015-01-01

    We show that Hořava-Lifshitz gravity theory can be employed as a covariant framework to build an effective field theory for the fractional quantum Hall effect that respects all the spacetime symmetries such as non-relativistic diffeomorphism invariance and anisotropic Weyl invariance as well as the gauge symmetry. The key to this formalism is a set of correspondence relations that maps all the field degrees of freedom in the Hořava-Lifshitz gravity theory to external background (source) fields among others in the effective action of the quantum Hall effect, according to their symmetry transformation properties. We originally derive the map as a holographic dictionary, but its form is independent of the existence of holographic duality. This paves the way for the application of Hořava-Lifshitz holography on fractional quantum Hall effect. Using the simplest holographic Chern-Simons model, we compute the low energy effective action at leading orders and show that it captures universal electromagnetic and geometric properties of quantum Hall states, including the Wen-Zee shift, Hall viscosity, angular momentum density and their relations. We identify the shift function in Hořava-Lifshitz gravity theory as minus of guiding center velocity and conjugate to guiding center momentum. This enables us to distinguish guiding center angular momentum density from the internal one, which is the sum of Landau orbit spin and intrinsic (topological) spin of the composite particles. Our effective action shows that Hall viscosity is minus half of the internal angular momentum density and proportional to Wen-Zee shift, and Hall bulk viscosity is half of the guiding center angular momentum density.

  11. 2009 Louisiana "HoCP" and "Ho" nursery and infield variety trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three years after selecting in single-stools in the seedling stage, scientists in the breeding program assign “HoCP” or “Ho” numbers to varieties advanced for further testing. These newly assigned varieties are planted in replicated nursery trials at three locations (Ardoyne Farm in Schriever, Iber...

  12. Uric Acid-Induced Adipocyte Dysfunction Is Attenuated by HO-1 Upregulation: Potential Role of Antioxidant Therapy to Target Obesity

    PubMed Central

    Sodhi, Komal; Hilgefort, Jordan; Banks, George; Gilliam, Chelsea; Stevens, Sarah; Ansinelli, Hayden A.; Getty, Morghan; Abraham, Nader G.; Shapiro, Joseph I.

    2016-01-01

    Increased uric acid levels have been implicated in the pathogenesis of metabolic syndrome. To examine the mechanisms by which this occurs, we hypothesized that an increase in heme oxygenase 1, a potent antioxidant gene, will decrease uric acid levels and adipocyte dysfunction via suppression of ROS and xanthine oxidase (XO) levels. We examined the effect of uric acid on adipogenesis in human mesenchymal stem cells (MSCs) in the presence and absence of cobalt protoporphyrin (CoPP), an HO-1 inducer, and tin mesoporphyrin (SnMP), an HO activity inhibitor. Uric acid increased adipogenesis by increasing NADPH oxidase expression and elevation in the adipogenesis markers C/EBPα, PPARγ, and Mest, while decreasing small lipid droplets and Wnt10b levels. We treated MSCs with fructose, a fuel source that increases uric acid levels. Our results showed that fructose increased XO expression as compared to the control and concomitant treatment with CoPP significantly decreased XO expression and uric acid levels. These beneficial effects of CoPP were reversed by SnMP, supporting a role for HO activity in mediating these effects. These findings demonstrate that increased levels of HO-1 appear crucial in modulating the phenotype of adipocytes exposed to uric acid and in downregulating XO and NADPH oxidase levels. PMID:26681956

  13. Uric Acid-Induced Adipocyte Dysfunction Is Attenuated by HO-1 Upregulation: Potential Role of Antioxidant Therapy to Target Obesity.

    PubMed

    Sodhi, Komal; Hilgefort, Jordan; Banks, George; Gilliam, Chelsea; Stevens, Sarah; Ansinelli, Hayden A; Getty, Morghan; Abraham, Nader G; Shapiro, Joseph I; Khitan, Zeid

    2016-01-01

    Increased uric acid levels have been implicated in the pathogenesis of metabolic syndrome. To examine the mechanisms by which this occurs, we hypothesized that an increase in heme oxygenase 1, a potent antioxidant gene, will decrease uric acid levels and adipocyte dysfunction via suppression of ROS and xanthine oxidase (XO) levels. We examined the effect of uric acid on adipogenesis in human mesenchymal stem cells (MSCs) in the presence and absence of cobalt protoporphyrin (CoPP), an HO-1 inducer, and tin mesoporphyrin (SnMP), an HO activity inhibitor. Uric acid increased adipogenesis by increasing NADPH oxidase expression and elevation in the adipogenesis markers C/EBPα, PPARγ, and Mest, while decreasing small lipid droplets and Wnt10b levels. We treated MSCs with fructose, a fuel source that increases uric acid levels. Our results showed that fructose increased XO expression as compared to the control and concomitant treatment with CoPP significantly decreased XO expression and uric acid levels. These beneficial effects of CoPP were reversed by SnMP, supporting a role for HO activity in mediating these effects. These findings demonstrate that increased levels of HO-1 appear crucial in modulating the phenotype of adipocytes exposed to uric acid and in downregulating XO and NADPH oxidase levels. PMID:26681956

  14. An independent hydrogen source

    SciTech Connect

    Kobzenko, G.F.; Chubenko, M.V.; Kobzenko, N.S.; Senkevich, A.I.; Shkola, A.A.

    1985-10-01

    Descriptions are given of the design and operation of an independent hydrogen source used in purifying and storing hydrogen. If LaNi/sub 5/ or TiFe is used as the sorbent, one can store about 500 liter of chemically bound hydrogen in a vessel of 0.9 liter. Molecular purification of the desorbed hydrogen is used. The IHS is a safe hydrogen source, since the hydrogen is trapped in the sorbent in the chemically bound state and in equilibrium with LaNi/sub 5/Hx at room temperature. If necessary, the IHS can serve as a compressor and provide higher hydrogen pressures. The device is compact and transportable.

  15. Measurement of HO2 chemical kinetics with a new detection method

    NASA Technical Reports Server (NTRS)

    Lee, Long C.; Suto, Masako

    1986-01-01

    Reaction rate constants of HO2+O3 were measured at various temperatures using a newly developed HO2 detection method. HO2 was detected by the OH(A-X) emission produced from photodissociative excitation of HO2 at 147 nm. In order to examine the possible interference of other emitting species with the HO2 detection, the photoexcitation processes of all the chemical species existing in the discharge flow tube were also investigated. The results are summarized.

  16. 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).

  17. Measurement of 63Ni and 59Ni by accelerator mass spectrometry using characteristic projectile X-rays

    NASA Astrophysics Data System (ADS)

    McAninch, J. E.; Hainsworth, L. J.; Marchetti, A. A.; Leivers, M. R.; Jones, P. R.; Dunlop, A. E.; Mauthe, R.; Vogel, J. S.; Proctor, I. D.; Straume, T.

    1997-03-01

    The long-lived isotopes of nickel (59Ni, 63Ni) 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 63Cu(n,p)63Ni 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 63Ni (t{1}/{2} = 100 y) requires the chemical removal of 63Cu, which is a stable isobar of 63Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 × 10-8 ({Cu}/{Ni}) using the reaction of Ni with carbon monoxide to form the gas Ni(CO)4. The Ni(CO)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 63Cu. In a demonstration experiment, 63Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a 252Cf source. We successfully measured 63Ni 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 1012 with quantitative retention of 63Ni. Detection sensitivity (3σ) was ˜ 20 fg 63Ni in 1 mg Ni carrier ({63Ni}/{Ni} ≈ 2 × 10-11). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for 59Ni (t{1}/{2} = 105 y). Initial work has been undertaken on the application of this isotope as a biomedical tracer in living systems.

  18. 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.

  19. Anomalous temperature dependence of the lattice parameters in HoPO{sub 4} and HoVO{sub 4}: Rare earth quadrupolar effects

    SciTech Connect

    Skanthakumar, S.; Loong, C.K.; Soderholm, L.; Nipko, J.; Richardson, J.W. Jr.; Abraham, M.M.; Boatner, L.A.

    1994-07-01

    The temperature dependence of the lattice parameters in tetragonal HoPO{sub 4} and HoVO{sub 4} was measured using neutron powder-diffraction techniques. Below about 100K, the lattice parameter a of HoPO{sub 4} increases with decreasing temperature while c decreases. In HoVO{sub 4}, the above behavior is reversed, that is, a decreases with decreasing temperature while c increases. Similar measurements on nonmagnetic LUP0{sub 4} and LuVO{sub 4} do not show any anomaly. This observation indicates that the unusual temperature dependence of the lattice constants is magnetic in origin. It can be explained in terms of a Ho{sup 3+} quadrupole interaction with the crystalline lattice. In particular, the calculated electronically-generated quadrupole moment of the Ho{sup 3+} in HoPO{sub 4} and HoVO{sub 4} exhibits a temperature dependence similar to that observed in the lattice parameters.

  20. Role of Yb(3+) ions on enhanced ~2.9 μm emission from Ho(3+) ions in low phonon oxide glass system.

    PubMed

    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 Ho(3+) ions in Yb(3+)/Ho(3+) co-doped oxide based tellurite glass system. This emission intensity has increased many folds upon Yb(3+): 985 nm excitation compared to direct Ho(3+) excitations due to efficient excited state resonant energy transfer through Yb(3+): (2)F5/2 → Ho(3+): (5)I5 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) cm(2) respectively which are comparable to other crystal/glass hosts and even better than ZBLAN fluoride glass host. Hence, this Ho(3+)/Yb(3+) 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

  2. 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

  3. Fragmentation Dynamics of Endohedral Fullerene Ho3N@C80 Ionized with Intense and Short X-Ray FEL Pulses

    NASA Astrophysics Data System (ADS)

    Murphy, Brendan; Xiong, Hui; Fang, Li; Osipov, Timur; Kukk, Edwin; Petrovic, Vladmir; Li, Heng; Sistrunk, Emily; Squibb, Richard; Feifel, Raimund; Ferguson, Kenneth; Krzywinski, Jacek; Sebastian, Sebastian; Guehr, Markus; Bostedt, Christoph; Bucksbaum, Philip; Berrah, Nora

    2015-05-01

    The photoionization and fragmentation dynamics of gas phase endohedral fullerenes Ho3N@C80 with intense femtosecond X-ray pulses from the Linac Coherent Light Source (LCLS) free electron laser (FEL) have been investigated. The central photon energy of the x-ray pulses was set at 1530 eV, targeting the absorption of the 3d electron on Ho. Multiphoton ionization led to the highest charge state observed on the parent molecule to be Ho3N@C805+ , suggesting a stable structure even with 5 charges on the parent molecule. We will present the different atomic and molecular fragments dynamics observed. This work is funded by the Department of Energy, Office of Science, Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under grant N. DE-FG02-92ER14299.A002 and in part by National Science Foundation under Grant No. 1404109.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Magnetic ordering in Ho2Fe2Si2C

    NASA Astrophysics Data System (ADS)

    Susilo, R. A.; Cadogan, J. M.; Cobas, R.; Hutchison, W. D.; Avdeev, M.; Campbell, S. J.

    2015-05-01

    We have used neutron diffraction and 57Fe Mössbauer spectroscopy, complemented by magnetisation and specific heat measurements, to examine the magnetic ordering of Ho2Fe2Si2C. We have established that Ho2Fe2Si2C orders antiferromagnetically below TN = 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 ] . 57Fe Mössbauer spectra collected below TN 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 57Fe spectra below TN, which is due to a transferred hyperfine field—estimated to be around 0.3 T at 10 K—from the Ho sublattice.

  11. Bridging exchange bias effect in NiO and Ni(core)@NiO(shell) nanoparticles

    NASA Astrophysics Data System (ADS)

    Rinaldi-Montes, Natalia; Gorria, Pedro; Martínez-Blanco, David; Fuertes, Antonio B.; Fernández Barquín, Luis; Puente-Orench, Inés; Blanco, Jesús A.

    2016-02-01

    Among all bi-magnetic core(transition metal)@shell(transition metal oxide) nanoparticles (NPs), Ni@NiO ones show an onset temperature for the exchange bias (EB) effect far below the Néel temperature of bulk antiferromagnetic NiO. In this framework, the role played by the magnetism of NiO at the nanoscale is investigated by comparing the microstructure and magnetic properties of NiO and Ni@NiO NPs. With the aim of bridging the two systems, the diameter of the NiO NPs (~4 nm) is chosen to be comparable to the shell thickness of Ni@NiO ones (~2 nm). The EB effect in Ni@NiO NPs is attributed to the exchange coupling between the core and the shell, with an interfacial exchange energy of ΔE~0.06 erg cm-2, thus comparable to previous reports on Ni/NiO interfaces both in thin film and NP morphologies. In contrast, the EB detected in NiO NPs is explained in a picture where uncompensated spins located on a magnetically disordered surface shell are exchange coupled to the antiferromagnetic core. In all the studied NPs, the variation of the EB field as a function of temperature is described according to a negative exponential law with a similar decay constant, yielding a vanishing EB effect around T~40-50 K. In addition, the onset temperature for the EB effect in both NiO and Ni@NiO NPs seems to follow a universal dependence with the NiO crystallite size.

  12. 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...

  13. Deformation attending internal nitridation of Ni-Ti alloys

    SciTech Connect

    Savva, G.C.; Weatherly, G.C.; Kirkaldy, J.S.

    1996-04-01

    Net volume increase attending precipitation is the source of a number of interesting deformation processes including creep and grain boundary sliding. Grain boundary sliding, a common high temperature deformation process, was observed in Ni-Al but was absent in Ni-Ti and Ag-In. It appears that in Ni-Ti, Ni is preferentially transported outwards along dislocation pipes and some twin boundaries countercurrent to a bulk stress driven vacancy flow (similar to the Nabarro-Herring creep attributed to Ni-Al). Some Ti may be preferentially transported outward by grain boundaries since at compositions near the transition to a superficial scale of TiN outward solute diffusion is significant. A strong element of Ni surface diffusion is involved in redistributing extruded Ni and producing facetted surface features. In respect to Ti diffusion towards the surface the authors have to record a distinction between the process and the classical Wagner models of frontal internal oxidation which applies to Ag-In and Ni-Al.

  14. On Hořava-Lifshitz cosmology

    NASA Astrophysics Data System (ADS)

    Chen, Bin

    2011-05-01

    We give a brief overview of the Hořava-Lifshitz-gravity theory, its modifications and its implications in cosmology. In particular, we discuss the various issues on the gravitational scalar mode, including its decoupling, its role as inflaton and its stability. Our analysis shows that the scalar mode could decouple naturally at λ = 1 due to the extra gauge symmetry. On the other hand, the fact that the scalar mode becomes ghost when 1/3 < λ < 1 is a real challenge to the theory. We try to overcome this problem by modifying the action such that the RG flow lies outside the problematic region. We discuss the cosmological implications of the theory.

  15. Comparison of the Pulmonary Oxidative Stress Caused by Intratracheal Instillation and Inhalation of NiO Nanoparticles when Equivalent Amounts of NiO Are Retained in the Lung

    PubMed Central

    Horie, Masanori; Yoshiura, Yukiko; Izumi, Hiroto; Oyabu, Takako; Tomonaga, Taisuke; Okada, Takami; Lee, Byeong-Woo; Myojo, Toshihiko; Kubo, Masaru; Shimada, Manabu; Morimoto, Yasuo

    2016-01-01

    NiO nanoparticles were administered to rat lungs via intratracheal instillation or inhalation. During pulmonary toxicity caused by NiO nanoparticles, the induction of oxidative stress is a major factor. Both intratracheal instillation and inhalation of NiO nanoparticles induced pulmonary oxidative stress. The oxidative stress response protein, heme oxygenase-1 (HO-1), was induced by the administration of NiO nanoparticles at both the protein and gene expression level. Additionally, certain oxidative-stress markers in the lung, such as 8-iso-prostaglandin F2α, thioredoxin, and inducible nitric oxide synthase were increased. Furthermore, the concentration of myeloperoxidase (MPO) in the lung was also increased by the administration of NiO nanoparticles. When the amount of NiO in the lung is similar, the responses against pulmonary oxidative stress of intratracheal instillation and inhalation are also similar. However, the state of pulmonary oxidative stress in the early phase was different between intratracheal instillation and inhalation, even if the amount of NiO in the lung was similar. Inhalation causes milder oxidative stress than that caused by intratracheal instillation. On evaluation of the nanoparticle-induced pulmonary oxidative stress in the early phase, we should understand the different states of oxidative stress induced by intratracheal instillation and inhalation. PMID:26797643

  16. Crystal-field excitations and magnetic properties of Ho{sup 3+} in HoVO{sub 4}

    SciTech Connect

    Skanthakumar, S.; Loong, C.; Soderholm, L.; Abraham, M.M.; Boatner, L.A.

    1995-05-01

    The magnetic excitations in HoVO{sub 4} were studied by neutron scattering and susceptibility techniques. Well-defined transitions between the crystal-field-split states of the Ho{sup 3+} ions were observed at 15, 40, and 100 K. The magnetic spectra were analyzed using a single-ion crystal-field model which includes intermediate coupling of the LS states of Ho. A quantitative comparison of the observed energies and intensities with the model was made and used to refine the five crystal-field parameters needed to calculate the Ho ionic wave functions and other magnetic properties. The nonmagnetic {Gamma}{sub 1}-singlet ground state (containing about 90% pure {vert_bar}8,0{r_angle} component) of the Ho ions, in conjunction with the next higher doublet state situated at 2.5 meV, strongly influences the low-temperature magnetic behavior. The calculated magnetic susceptibility, which exhibits an easy plane coinciding with the crystallographic {ital a}-{ital b} plane at low temperatures, agrees very well with the experimental data obtained from single-crystal measurements. The magnetic properties of HoVO{sub 4} are contrasted with those of an isostructural compound HoPO{sub 4} which has a 98% pure {vert_bar}8,7{r_angle}-doublet ground state. The difference in the crystal-field-level structure between these two compounds is reflected in a sign change of the {ital B}{sub 0}{sup 2} crystal-field parameter. Despite the overall tetragonal crystal structure of HoVO{sub 4}, which predicts double degeneracy for each {Gamma}{sub 5} state, a small splitting in the first-excited doublet was clearly observed at low temperatures.

  17. 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.

  18. 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. PMID:25811311

  19. Bonding in zerovalent Ni compounds - NiN2 and Ni(N2)4 compared with NiCO and Ni(CO)4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Barnes, Leslie A.

    1989-01-01

    Calculations are carried out on NiN2, which may be considered a prototypical metal surface-ligand system. A large Gaussian basis set and an MCPF treatment of electron correlation are used. Consideration is also given to the 2Sigma(+) states of NiN2(-), NiCO(-), and NiN2(+), the low-lying 2Delta and 2Pi states of NiN2(+), and the 1A1 states of Ni(CO)4 and Ni(N2)4.

  20. 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.

  1. Aluminizing a Ni sheet through severe plastic deformation induced by ball collisions

    NASA Astrophysics Data System (ADS)

    Romankov, S.; Shchetinin, I. V.; Park, Y. C.

    2015-07-01

    Aluminizing a Ni sheet was performed through severe plastic deformation induced by ball collisions. The Ni sheet was fixed in the center of a mechanically vibrated vial between two connected parts. The balls were loaded into the vial on both sides of the Ni disk. Al disks, which were fixed on the top and the bottom of the vial, served as the sources of Al contamination. During processing, the Ni sheet was subject to intense ball collisions. The Al fragments were transferred and alloyed to the surface of the Ni sheet by these collisions. The combined effects of deformation-induced plastic flow, mechanical intermixing, and grain refinement resulted in the formation of a dense, continuous nanostructured Al layer on the Ni surface on both sides of the sheet. The Al layer consisted of Al grains with an average size of about 40 nm. The Al layer was reinforced with nano-sized Ni flakes that were introduced from the Ni surface during processing. The local amorphization at the Ni/Al interface revealed that the bonding between Ni and Al was formed by mechanical intermixing of atomic layers at the interface. The hardness of the fabricated Al layer was 10 times that of the initial Al plate. The ball collisions destroyed the initial rolling texture of the Ni sheet and induced the formation of the mixed [1 0 0] + [1 1 1] fiber texture. The laminar rolling structure of the Ni was transformed into an ultrafine grain structure.

  2. Using Diffusion Modeling to Understand Ni Variability and Magmatic Histories of Hawaiian Olivines

    NASA Astrophysics Data System (ADS)

    Lynn, K. J.; Garcia, M. O.; Shea, T.

    2014-12-01

    The Ni content of olivine has been used extensively for inferring the source lithology, and depth and temperature of generation for basaltic magma in various tectonic settings. Conflicting interpretations have been derived using Ni because Hawaiian basalts show large variations in olivine Ni content (up to a factor of two) for a given forsterite (Fo). A detailed study of historical basalts at Kilauea volcano was undertaken using high-precision EPMA to better understand the cause of Ni variation in Hawaiian basalts. Experimental studies predict that Ni abundance in olivine should be positively correlated with Fo during growth. Element maps and core-rim transects of crystals strongly zoned in Fo show that many Kilauea olivines violate this relationship. They have decoupled profiles in which Fo decreases towards the rim by up to 5 mol% and Ni remains nearly constant. Here, we evaluate whether the Ni variability and Fo-Ni decoupling result from (1) diffusive re-equilibration and/or (2) sectioning effects rather than being primary growth features of those olivines. We used 1D diffusion modeling of Mg, Ni, and Ca from EPMA profiles to determine if decoupling is caused by diffusive re-equilibration. Calculated timescales (e.g. 2.2-3.1 yr) are in excellent agreement for all elements and transects within individual crystals, suggesting that the Fo-Ni decoupling is a primary growth feature of the olivine. Sectioning effects on Fo-Ni zoning were evaluated using 3D diffusion models of numerical olivines, which were constructed using realistic morphologies found in nature. Off-center and highly oblique sections have Fo and Ni extremums offset from the geometric center in 2D sections. Analyses of normally zoned olivine with decoupled Fo-Ni will yield similar Ni at variable Fo, introducing "Ni-enriched", low Fo data. These "Ni-enriched" olivine compositions may contribute to the range of interpretations derived from current datasets

  3. 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

  4. 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

  5. Materials Data on CaNiAsHO5 (SG:19) 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

  6. Materials Data on HoGaNi (SG:62) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-02-09

    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

  7. Materials Data on HoNi5 (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

  8. Materials Data on HoNi3 (SG:166) 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

  9. Is HO{sup 2 sub +} a detectable interstellar molecule?

    SciTech Connect

    Widicus Weaver, S. L.; Woon, D. E.; Ruscic, B.; McCall, B. J.; Chemical Sciences and Engineering Division; Univ. of Illinois

    2009-05-20

    Although molecular oxygen, O{sub 2}, has long been thought to be present in interstellar environments, it has only been tentatively detected toward one molecular cloud. The fractional abundance of O{sub 2} determined from these observations is well below that predicted by astrochemical models. Given the difficulty of O{sub 2} observations from ground-based telescopes, identification of a molecule that could be used as a tracer of O{sub 2} in interstellar environments would be quite useful. To this end, we have undertaken a collaborative examination of HO{sub 2}{sup +} in an attempt to evaluate the feasibility of its detection in interstellar clouds. We have conducted high-level ab initio calculations of its structure to obtain its molecular parameters. The reaction responsible for the formation of HO{sub 2}{sup +} is nearly thermoneutral, and so a careful analysis of its thermochemistry was also required. Using the Active Thermochemical Tables approach, we have determined the most accurate values available to date for the proton affinities of O{sub 2} and H{sub 2}, and the enthalpy, Gibbs energy, and equilibrium constant for the reaction H{sub 3}{sup +} + O{sub 2} {yields} HO{sub 2}{sup +} + H{sub 2}. We find that while this reaction is endothermic by 50 {+-} 9 cm{sup -1} at 0 K, its equilibrium is shifted toward HO{sub 2}{sup +} at the higher temperatures of hot cores. We have examined the potential formation and destruction pathways for HO{sub 2}{sup +} in interstellar environments. Combining this information, we estimate the HO{sub 2}{sup +} column density in dense clouds to be {approx}10{sup 9} cm{sup -2}, which corresponds to line brightness temperatures of {le} 0.2 mK. If our results prove correct, HO{sub 2}{sup +} is clearly not a detectable interstellar molecule.

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

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Smialek, J. L.; Barrett, C. A.

    1989-01-01

    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-Al203 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.

  11. 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.

  12. Powder Neutron Diffraction Study of HoCoGa5

    SciTech Connect

    Kabayashi, Riki; Kaneko, Koji; Wakimoto, Shuichi; Chi, Songxue; Sanada, Naoyuki; Watanuki, Ryuta; Suzuki, Kazuya

    2013-01-01

    We have studied successive magnetic transitions of HoCoGa5 at TN1 = 9.6 K and TN2 = 7.5 K by using powder neutron diffraction. Apparent superlattice peaks were observed at temperatures below TN1. With further decreases temperature, the patterns exhibit a substantial change at temperatures below TN2. The observed magnetic peaks at 8 K (AntiFerromagnetic InCommensurate (AFIC) phase : TN2 < T < TN1) can be represented by the propagation vector qL = (1/2 0 ) with = 0.35(2). In contrast, the magnetic structure becomes commensurate with qC = (1/2 0 1/2) at 4 K (AntiFerromagnetic Commensurate (AFC) phase : T < TN2). The temperature dependence of magnetic intensity shows an apparent temperature hysteresis at TN2, indicates a first-order transition at TN2. Analysis of the integrated intensity at 4 K reveals that the Ho moment with a size of 8.6(2) B, oriented parallel to the c-axis in the AFC phase. While the successive transitions of HoCoGa5 are different from those of TbCoGa5, the magnetic structure in the AFC phase of HoCoGa5 is the same as the AFTb I of TbCoGa5, and may indicate an additional transition at a lower temperature in HoCoGa5.

  13. 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.

  14. Application of groundwater sustainability indicators to the Upper Pliocene aquifer in Ho Chi Minh city, Viet Nam

    NASA Astrophysics Data System (ADS)

    Ngo, T. M.; Lee, J.; Lee, H.; Woo, N. C.

    2013-12-01

    Groundwater plays an importance role for domestic, industrial, and agricultural uses in Ho Chi Minh city, Viet Nam. This study is objected to evaluate the sustainability of groundwater by using groundwater sustainability indicators (GWSIs) defined by UNESCO/IAEA/IAH Working Group on Groundwater Indicators at aquifer scale (the Upper Pliocene aquifer). There are four main indicators selected and one new indicator designed for the particular characteristic of Ho Chi Minh city which is under influence of by saline-water intrusion. The results indicated groundwater of the Upper Pliocene aquifer, the main groundwater supply source, is generally in the unsustainable state. The abstraction of groundwater, which was much greater than its capability, is probably causing the serious state of annual groundwater depletion and saline-water intrusion. The GWSIs, which expressed in such a simple way but scientifically-based and policy-relevant, proved its usefulness in evaluating the sustainability of groundwater at the aquifer scale in Ho Chi Minh city, and subsequently should be incorporated in water resource management practices.

  15. 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.

  16. Pistacia chinensis inhibits NO production and upregulates HO-1 induction via PI-3K/Akt pathway in LPS stimulated macrophage cells.

    PubMed

    Yayeh, Taddesse; Hong, Mei; Jia, Qi; Lee, Young-Chul; Kim, Hyun-Jin; Hyun, Eujin; Kim, Tae-Wan; Rhee, Man Hee

    2012-01-01

    Pistacia chinensis has been used for various purposes in China including as an understock for grafting Pistacia vera. However, little attention was given to its health promoting effects. Therefore, in this study, we investigated the effect of Pistacia chinensis methanolic extract (PCME) containing resorcinol class of phenolic lipids on pro-inflammatory mediators and heme oxygenase-1(HO-1) in lipopolysaccharide stimulated RAW264.7 cells. While PCME (2.5-10 μg/ml) inhibited mRNA expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and interleukin (IL)-6, it up-regulated HO-1 expression. Likewise, PCME inhibited iNOS protein expression, but not COX-2, and reduced nitric oxide (NO) release. Moreover, Phosphorylated c-Jun N-terminal Kinase (JNK) was attenuated dose-dependently in PCME pre-treated RAW264.7 cells. In addition, PCME up-regulated HO-1 protein expression was diminished by pre-treatment of PI-3K inhibitor. Furthermore, nuclear factor erythroid 2 related factor 2 (Nrf2) repressor was attenuated time-dependently during PCME treatment. Taken together, our study showed (for the first time) that PCME inhibited NO production and up-regulated HO-1 induction via PI-3K/Akt pathway, suggesting the role of Pistacia chinensis as potential sources of anti-inflammatory and antioxidant natural compounds. PMID:22928837

  17. Visualization of 2-μm radiation by BiF3:Ho3+ and BiF3:Ho3+/Yb3+ ceramics

    NASA Astrophysics Data System (ADS)

    Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Grishin, I. A.

    2016-06-01

    A series of ceramic samples of the compositions BiF3:1%Ho3+, BiF3:4%Ho3+, BiF3:1%Ho3+ + 1%Yb3+, and BiF3:1%Ho3+ + 3%Yb3+ is synthesized and the conversion of Tm:YLF laser radiation (λ = 1908 nm) is studied. The luminescence spectra exhibit bands in the regions of 490, 545, and 650 nm. The kinetic measurements of the afterglow of the green and red bands show that the population of the 5 S 2 and 5 F 4 states in the BiF3:1%Ho3+ samples occurs due to successive absorption of excitation photons, while the 5 F 5 level of Ho3+ is populated due to the ion-ion interaction. Codoping with Yb3+ leads to a decrease in the visualization threshold power density to 2 W/cm2.

  18. Proton Radioactivity Measurements at HRIBF: Ho, Lu, and Tm Isotopes

    SciTech Connect

    Akovali, Y.; Batchelder, J.C.; Bingham, C.R.; Davinson, T.; Ginter, T.N.; Gross, C.J.; Grzywacz, R.; Hamilton, J.H.; Janas, Z.; Karny, M.; Kim, S.H.; MacDonald, B.D.; Mas, J.F.; McConnell, J.W.; Piechaczek, A.; Ressler, J.J.; Rykaczewski, K.; Slinger, R.C.; Szerypo, J.; Toth, K.S.; Weintraub, W.; Woods, P.J.; Yu, C.-H.; Zganjar, E.F.

    1998-11-13

    Two new isotopes, {sup 145}Tm and {sup 140}Ho and three isomers in previously known isotopes, {sup 141m}Ho, {sup 150m}Lu and {sup 151m}Lu have been discovered and studied via their decay by proton emission. These proton emitters were produced at the Holifield Radioactive Ion Beam Facility (HRIBF) by heavy-ion fusion-evaporation reactions, separated in A/Q with a recoil mass spectrometer (RMS), and detected in a double-sided silicon strip detector (DSSD). The decay energy and half-life was measured for each new emitter. An analysis in terms of a spherical shell model is applied to the Tm and Lu nuclei, but Ho is considerably deformed and requires a collective model interpretation.

  19. Spectroscopy of {sup 144}Ho using recoil-isomer tagging

    SciTech Connect

    Mason, P. J. R; Cullen, D. M.; Scholey, C.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Peura, P.; Puurunen, A.; Rahkila, P.; Ruotsalainen, P.; Sorri, J.; Saren, J.; Uusitalo, J.; Xu, F. R.

    2010-02-15

    Excited states in the proton-unbound odd-odd nucleus {sup 144}Ho have been populated using the {sup 92}Mo({sup 54}Fe,pn){sup 144}Ho reaction and studied using the recoil-isomer-tagging technique. The alignment properties and signature splitting of the rotational band above the I{sup p}i=(8{sup +}){sup 144m}Ho isomer have been analyzed and the isomer confirmed to have a pih{sub 11/2} x nuh{sub 11/2} two-quasiparticle configuration. The configuration-constrained blocking method has been used to calculate the shapes of the ground and isomeric states, which are both predicted to have triaxial nuclear shapes with |gamma|approx =24 deg.

  20. Proton-proton intensity interferometry: Space-time structure of the emitting zone in Ni+Ni collisions

    SciTech Connect

    Korolija, M.; Cindro, N.; Shapira, D.

    1995-12-31

    A brief description is given of the Hanbury-Brown-Twiss effect method for determining the space-time structure of the proton-emitting source in a nucleus-nucleus collision. In this context a measurement of exclusive p-p correlations from {sup 58}Ni+{sup 58}Ni at 850 MeV is analyzed. The data served to study the directional dependence of the p-p correlation function and, for the first time, extract separately the source size and the particle-emission time.

  1. Template-based synthesis of Ni nanorods on silicon substrate

    NASA Astrophysics Data System (ADS)

    Jin, Xiaoyun; Hu, Yan; Wang, Yao; Shen, Ruiqi; Ye, Yinghua; Wu, Lizhi; Wang, Shouxu

    2012-01-01

    Free-standing nickel (Ni) nanorods were successfully prepared by pulsed electrodeposition using porous alumina membrane (PAM) on titanium (Ti) pre-coated silicon (Si) substrate. Initially, Si substrate was coated with subsequent layers of Ti (∼200 nm) and Al (∼600 nm) by sputtering process. The PAM/Ti/Si structure was fabricated by a two-step anodization in 0.3 M oxalic acid under a constant voltage of 40 V, and then used to grow Ni nanorods by pulsed electrodeposition. Finally, an Al layer was deposited on the Ni nanorods. The relationship between the pore-widening time and the pore diameter of the PAM on Si was also investigated. Field emission scanning electron microscopy (FESEM) was employed to observe the morphology of PAM, Ni nanorods and Al/Ni heterostructure. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphological and structural properties of Ni nanorods, respectively. Also, the compositional properties of the samples were characterized by energy dispersive X-ray spectra (EDS). The pore diameter and the pore length of the PAM were approximately 54.2 ± 12.2 nm and 800 nm, respectively. The Ni nanorods stand perpendicularly on the substrate, whose diameter and length were similar to the PAM. The Ni nanorods give an XRD pattern of face-centered cubic crystal structure. Ni nanorods with deposited a layer of Al have the potential application of a heat source or energetic material in the silicon-based micro-electromechanical systems (MEMS) compatible device.

  2. Lattice effects in HoVo 3 single crystal

    NASA Astrophysics Data System (ADS)

    Sikora, M.; Marquina, C.; Ibarra, M. R.; Nugroho, A. A.; Palstra, T. T. M.

    2007-09-01

    We report the study of lattice effects in the Mott insulator HoVO 3 performed by means of linear thermal expansion on a single crystal in the temperature range 10-290 K. The holmium orthovanadate HoVO 3 reveals gradual orbital ordering (OO) below TOO=200 K and orders antiferromagnetically at TN=113 K. A first-order structural phase transition takes place at TS˜38 K, which is probably accompanied by change of the OO type and hence the type of antiferromagnetic spin ordering.

  3. Electronic transitions of Ho in Pb2Sr2HoCu3O8 observed by inelastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Soderholm, L.; Loong, C.-K.; Xue, J. S.; Hammonds, J. P.; Greedan, J. E.; Maric, M.

    1993-05-01

    The electronic behavior of the 5I8 Russell Saunders ground multiplet of Ho3+ in Pb2Sr2HoCu3O8 has been investigated using inelastic neutron scattering. We observe ten peaks in the excitation spectra that are associated with crystal field transitions. The peaks are only slightly broader than expected from instrument resolution, indicating that there are no strong interactions between the local Ho f states and the CuO conduction states. Comparing the energies and intensities of the experimental peaks with those expected from modeling convinces us that there are at least three states populated at the temperature of our experiment (15 K), making the assignments of transitions very difficult in the absence of further data.

  4. [NiIII(OMe)]-mediated reductive activation of CO2 affording a Ni(κ1-OCO) complex

    DOE PAGESBeta

    Chiou, Tzung -Wen; Tseng, Yen -Ming; Lu, Tsai -Te; Weng, Tsu -Chien; Sokaras, Dimosthenes; Ho, Wei -Chieh; Kuo, Ting -Shen; Jang, Ling -Yun; Lee, Jyh -Fu; Liaw, Wen -Feng

    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

  5. Simple synthesis of Ni-containing ordered mesoporous carbons and their adsorption/desorption of methylene orange.

    PubMed

    Tian, Yong; Wang, Xiufang; Pan, Yufang

    2012-04-30

    A simple route has been developed to synthesize magnetic Ni-containing ordered mesoporous carbons (Ni/OMCs) without using a solvent for dissolving carbon precursor or magnetic source. The adsorption and desorption of methylene orange (MO) on the obtained Ni/OMCs were investigated. The effects of Ni(NO(3))(2) loading amount and carbonization temperature on the morphologies, the structural parameters and magnetic properties of these Ni/OMCs were evaluated by X-ray diffraction(XRD), N(2) sorption analysis, transmission electron microscopy(TEM) and physical property measurements. With the increase of Ni(NO(3))(2) loading amount, the ordering of the mesoporous structures, the specific surface area and the total pore volumes of Ni/OMCs decreased, but the pore diameters of Ni/OMCs and the sizes of Ni particle increased. The saturation magnetization strength could be easily adjusted by varying the amount of Ni(NO(3))(2). The specific surface area and total pore volumes decreased with the increasing of carbonization temperature. The size of Ni particle was the biggest at 750°C. The adsorption of MO into Ni/OMCs followed the Sips adsorption model. More interestingly, a simple equation was obtained and was proved to well fit the desorption behavior of MO on Ni/OMCs. The values for the relative fitted parameters were obtained and the physical meanings of the parameters were well defined. PMID:22366315

  6. 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.

  7. Magnetic properties of Ni/NiO nanocomposites synthesized by one step solution combustion method

    NASA Astrophysics Data System (ADS)

    Ganeshchandra Prabhu, V.; Shajira, P. S.; Lakshmi, N.; Junaid Bushiri, M.

    2015-12-01

    Ni/NiO nanocomposites were synthesized using solution combustion method and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX) and carbon, hydrogen, nitrogen (CHN) analyser. The Ni or NiO content in Ni/NiO nanocomposites vary with the quantity of HNO3 used for the synthesis. Magnetic coercivity (Hc) of Ni/NiO nanocomposites is found to be 413 Oe which can be used in magnetic applications. A feeble exchange bias of 7 Oe is seen from the NiO rich Ni/NiO.

  8. Optical transitions of Ho(3+) in oxyfluoride glasses and upconversion luminescence of Ho(3+)/Yb(3+)-codoped oxyfluoride glasses.

    PubMed

    Feng, Li; Wu, Yinsu

    2015-05-01

    Optical properties of Ho(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Ho(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980nm excitation. The effects of composition, concentration of the doping ions, and excitation pump power on the upconversion emissions were also systematically studied. PMID:25703369

  9. 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.

  10. Synergism between polyurethane and polydopamine in the synthesis of Ni-Fe alloy monoliths.

    PubMed

    Naresh Kumar, Thangavel; Sivabalan, Santhana; Chandrasekaran, Naveen; Phani, Kanala Lakshminarasimha

    2015-02-01

    Herein, we report the first synthesis of a light-weight macroporous 3-D alloy monolith of Ni-Fe/C using synergism between polydopamine (pDA) and polyurethane (pU); in situ formed polyurethane (pU) enables efficient mixing of pDA (carbon source) and Ni-FeOx resulting in Ni-Fe alloy monoliths at a temperature as low as ∼600 °C. The monolithic Ni-Fe/C exhibits enhanced oxygen evolution activity. PMID:25531680

  11. 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.

  12. Single frequency fiber laser at 2.05 μm based on Ho-doped germanate glass fiber

    NASA Astrophysics Data System (ADS)

    Wu, Jianfeng; Yao, Zhidong; Zong, Jie; Chavez-Pirson, Arturo; Peyghambarian, Nasser; Yu, Jirong

    2009-02-01

    A single frequency fiber laser operating near 2 micron with over 50 mW output power has been demonstrated by using a short piece of newly developed single mode holmium-doped germanate glass fiber. Laser from 2004 nm to 2083 nm was demonstrated from a short Ho-doped fiber laser cavity. A heavily thulium-doped germanate fiber was used as an in-band pump source for the holmium-doped fiber laser. The single frequency fiber laser can be thermally tuned.

  13. Solubility Measurements of Crystalline NiO in Aqueous Solution as a Function of Temperature and pH

    SciTech Connect

    Palmer, Donald; Benezeth, Pascale; Xiao, Caibin {nmn}; Wesolowski, David J; Anovitz, Lawrence {Larry} M

    2011-01-01

    Abstract Results of solubility experiments involving crystalline nickel oxide (bunsenite) in aqueous solutions are reported as functions of temperature (0 to 350 C) and pH at pressures slightly exceeding (with one exception) saturation vapor pressure. These experiments were carried out in either flow-through reactors or a hydrogen-electrode concentration cell for mildly acidic to near neutral pH solutions. The results were treated successfully with a thermodynamic model incorporating only the unhydrolyzed aqueous nickel species (viz., Ni2+ ) and the neutrally charged hydrolyzed species (viz., Ni(OH)02 ). The thermodynamic quantities obtained at 25 C and infinite dilution are, with 2 uncertainties: log10Ko s0 = (12.40 0.29), rGo m = (70.8 1.7) kJ mol 1; rHo m = (105.6 1.3) kJ mol 1; rSo m = (116.6 3.2) J K 1 mol 1; rCo p,m = (0 13) J K 1 mol 1; and log10Ko s2 = (8.76 0.15); rGo m = (50.0 1.7) kJ mol 1; rHo m = (17.7 1.7) kJ mol 1; rSo m = (108 7) J K 1 mol 1; rCo p,m = (108 3) J K 1 mol 1. These results are internally consistent, but the latter set differs from those gleaned from previous studies recorded in the literature. The corresponding thermodynamic quantities for the formation of Ni2+ and Ni(OH)02 are also estimated. Moreover, the Ni(OH) 3 anion was never observed, even in relatively strong basic solutions (mOH = 0.1 mol kg 1), contrary to the conclusions drawn from all but one previous study.

  14. Octanuclear Heterobimetallic {Ni4Ln4} Assemblies Possessing Ln4 Square Grid [2 × 2] Motifs: Synthesis, Structure, and Magnetism.

    PubMed

    Biswas, Sourav; Goura, Joydeb; Das, Sourav; Topping, Craig V; Brambleby, Jamie; Goddard, Paul A; Chandrasekhar, Vadapalli

    2016-09-01

    Octanuclear heterobimetallic complexes, [Ln4Ni4(H3L)4(μ3-OH)4(μ2-OH)4]4Cl·xH2O·yCHCl3 (Dy(3+), x = 30.6, y = 2 (1); Tb(3+), x = 28, y = 0 (2) ; Gd(3+), x = 25.3, y = 0 (3); Ho(3+), x = 30.6, y = 3 (4)) (H5L = N1,N3-bis(6-formyl-2-(hydroxymethyl)-4-methylphenol)diethylenetriamine) are reported. These are assembled by the cumulative coordination action of four doubly deprotonated compartmental ligands, [H3L](2-), along with eight exogenous -OH ligands. Within the core of these complexes, four Ln(3+)'s are distributed to the four corners of a perfect square grid while four Ni(2+)'s are projected away from the plane of the Ln4 unit. Each of the four Ni(2+)'s possesses distorted octahedral geometry while all of the Ln(3+)'s are crystallographically equivalent and are present in an elongated square antiprism geometry. The magnetic properties of compound 3 are dominated by an easy-plane single-ion anisotropy of the Ni(2+) ions [DNi = 6.7(7) K] and dipolar interactions between Gd(3+) centers. Detailed ac magnetometry reveals the presence of distinct temperature-dependent out-of-phase signals for compounds 1 and 2, indicative of slow magnetic relaxation. Magnetochemical analysis of complex 1 implies the 3d and the 4f metal ions are engaged in ferromagnetic interactions with SMM behavior, while dc magnetometry of compound 2 is suggestive of an antiferromagnetic Ni-Tb spin-exchange with slow magnetic relaxation due to a field-induced level crossing. Compound 4 exhibits an easy-plane single-ion anisotropy for the Ho(3+) ions and weak interactions between spin centers. PMID:27500314

  15. 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. PMID:26910881

  16. Urban photochemistry in central Tokyo: 1. Observed and modeled OH and HO2 radical concentrations during the winter and summer of 2004

    NASA Astrophysics Data System (ADS)

    Kanaya, Yugo; Cao, Renqiu; Akimoto, Hajime; Fukuda, Masato; Komazaki, Yuichi; Yokouchi, Yoko; Koike, Makoto; Tanimoto, Hiroshi; Takegawa, Nobuyuki; Kondo, Yutaka

    2007-11-01

    We used laser-induced fluorescence to measure the concentrations of OH and HO2 radicals in central Tokyo during two intensive campaigns (IMPACT IV and IMPACT L) in January-February and July-August 2004. The estimated detection limit for the 10-min data was 1.3 × 105 cm-3 for the nighttime and 5.2 × 105 cm-3 for the daytime. The median values of the daytime peak concentrations of HO2 were 1.1 and 5.7 pptv for the winter and summer periods, respectively, while the values for OH were 1.5 × 106 and 6.3 × 106 cm-3. High HO2 mixing ratios (>50 pptv) were observed on a day in summer when O3 mixing ratios exceeded 100 ppbv. The average nighttime concentrations of HO2 were 0.7 and 2.6 pptv for the winter and summer periods, respectively, while the values for OH were 1.8 × 105 and 3.7 × 105 cm-3. A photochemical box model constrained by ancillary observations was able to reproduce daytime OH concentrations reasonably well for both periods, although daytime HO2 concentrations were underestimated in winter and overestimated in summer. Increasing the wintertime hydrocarbon concentrations in the model led to an increase in daytime HO2 concentrations, thereby showing better agreement with observations; however, the model continued to underestimate HO2 concentrations at high NO mixing ratios. This underestimate was most pronounced in the mornings of both periods and during the daytime in winter. We studied processes that are capable of explaining this discrepancy, including unknown reactions of HNO4 or an unidentified HOx source that is linearly scalable to the NO mixing ratio. The important processes in terms of producing radicals were the olefin + O3 reactions in the nighttime of both periods and during the daytime in winter, the photolysis of carbonyls in the daytime for both periods, and the photolysis of HONO during the daytime in winter (using measured HONO concentrations) and during mornings in summer (using estimated HONO concentrations).

  17. Registration of ‘Ho 02-113’ Sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ho 02-113’ sugarcane was released by the USDA-ARS Sugarcane Research Unit working cooperatively with the Louisiana State University Agricultural Center, and the American Sugarcane League of the U.S.A. This high-fiber sugarcane variety was released for use as a biofuel feedstock to fill the rising i...

  18. P8 deficiency increases cellular ROS and induces HO-1.

    PubMed

    Weis, Sebastian; Bielow, Tobias; Sommerer, Ines; Iovanna, Juan; Malicet, Cédric; Mössner, Joachim; Hoffmeister, Albrecht

    2015-01-01

    The gene p8 encodes for a small cytoprotective protein with no apparent enzymatic activity being proposed to act as co-transcription factor whose expression is increased during inflammation. Recent data from astrocytes demonstrates that p8 suppression leads to induction of heme oxygenase 1 (HO-1). Here, we assessed the cross-talk between p8 and HO-1 in mouse embryonic fibroblasts (MEF) observing an increased expression of HO-1 in p8-deficient (p8(-/-)) MEFs in non-treated and treated conditions. This effect was independent of the cell cycle. Our findings revealed that generation of reactive oxygen species (ROS) was higher in p8(-/-) MEFs. Mitochondria and NADPH oxidases were not the origin of ROS. This observation was not restricted to MEF as suppression of p8 gene transcription in MiaPaCa-2 cells also led to increased intracellular ROS. Additionally, p8 deficiency did not affect the Rac1 dependant NADPH oxidase complex. Our data shows that p8 deficiency increases ROS and subsequently the expression of anti-oxidative enzymes, such as HO-1, suggesting an involvement in the anti-oxidative defense. Moreover, we suggest that the severity of AP observed in p8(-/-) mice is induced by an impaired anti oxidative capacity of the pancreas, which is caused by increased generation of ROS. PMID:25475530

  19. 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.

  20. 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.

  1. 2008 Louisiana "HoCP" Nursery and Infield Variety Trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three years after selection in single-stools at the seedling stage, scientists in the breeding program assign permanent “HoCP” or “Ho” numbers to experimental varieties advanced for further testing. These newly assigned varieties are planted in replicated nursery trials at three locations (Ardoyne ...

  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. 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.

  4. 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.

  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. Low temperature magnetic transitions of single crystal HoBi

    SciTech Connect

    Fente, A.; Suderow, H.; Vieira, S.; Nemes, N. M.; Garcia-Hernandez, M.; Budko, Sergei L.; Canfield, Paul C.

    2013-09-04

    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.

  7. The prosecution of Taiwan sexuality researcher and activist Josephine Ho.

    PubMed

    Wang, Ping

    2004-05-01

    In April 2003, following a newspaper report of a hyperlink to a website on bestiality on the Sexuality Databank website of the Center for the Study of Sexualities, National Central University, Taipei, Taiwan, 14 conservative NGOs filed charges against the Center's founder, Josephine Ho, for "propagating obscenities that corrupt traditional values." Ho has been researching sexuality and supporting freedom for marginalised sexual minorities for ten years. In a public statement in response to the charges, she said that the work of scholarly research must not be dictated by prejudice and that differences in sexual values should not be arbitrated by law and should be open for public discussion. As the legal process began in January 2004, Ho's supporters in Taiwan have called for the preservation of the Taiwan Constitutional decree on integrity and autonomy of academic research and freedom of expression on the internet, for the University to resist calls to dismiss Ho from her post, and for respect for freedom of speech and expression and the right to create spaces to educate people about non-normative sexualities. PMID:15242216

  8. 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...

  9. 2010 Louisiana "Ho" nursery and infield variety trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three years after selecting in single-stools in the seedling stage, scientists in the SRU’s sugarcane breeding program assign “HoCP” or “Ho” numbers to varieties advanced for further testing. These newly assigned varieties are planted in replicated nursery trials at the SRU’s Ardoyne Farm in Schrie...

  10. 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.

  11. Production and characterization of 166Ho polylactic acid microspheres.

    PubMed

    Yavari, Kamal; Yeganeh, Ehsan; Abolghasemi, Hossein

    2016-01-01

    Microsphere and particle technology with selective transport of radiation represents a new generation of therapeutics. Poly-L-lactic acid (PLLA) microspheres loaded with holmium-166 acetylacetonate ((166)Ho-PLLA-MS) are novel microdevices. In this research, (165)HoAcAc-PLLA microparticles were prepared by the solvent evaporation technique. Microspheres were irradiated at Tehran Research Reactor. The diameter and surface morphologies were characterized by particle sizer and scanning electron microscopy before and after irradiation. The complex stability, radiochemical purity, and in vivo biodistribiotion were checked in the final solution up to 3 days. In this study, (166)Ho-PLLA spherical particles with a smooth surface and diameter of 20-40 µm were obtained, which were stable in vitro and in vivo studies. Neutron irradiation did not damage the particles. The ease with which the PLLA spheres could be made in the optimal size range for later irradiation and their ability to retain the (166)Ho provided good evidence for their potential use in radioembolization. PMID:26691104

  12. 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 ...

  13. 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.

  14. The electrodeposition of FeCrNi stainless steel: microstructural changes induced by anode reactions.

    PubMed

    Hasegawa, Madoka; Yoon, Songhak; Guillonneau, Gaylord; Zhang, Yucheng; Frantz, Cédric; Niederberger, Christoph; Weidenkaff, Anke; Michler, Johann; Philippe, Laetitia

    2014-12-21

    The FeCrNi alloy, whose composition is close to that of stainless steel 304, was prepared by electrodeposition and characterized. Nanocrystalline FeCrNi (nc-FeCrNi) was obtained by employing a double-compartment cell where the anode is separated from the cathode compartment, while amorphous FeCrNi (a-FeCrNi) was deposited in a conventional single electrochemical cell. The carbon content of nc-FeCrNi was found to be significantly lower than that of a-FeCrNi, suggesting that carbon inclusion is responsible for the change in the microstructure. The major source of carbon is associated with the reaction compounds at the anode electrode, presumably decomposed glycine. Crystal structure analysis by XRD and TEM revealed that the as-deposited nc-FeCrNi deposits consist of α-Fe which transforms to γ-Fe upon thermal annealing. Nanoindentation tests showed that nc-FeCrNi exhibits higher hardness than a-FeCrNi, which is consistent with the inverse Hall-Petch behavior. PMID:25367332

  15. 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. PMID:23455117

  16. Resonantly pumped continuous-wave mode-locked Ho:YAP laser

    NASA Astrophysics Data System (ADS)

    Duan, X. M.; Lin, W. M.; Cui, Z.; Yao, B. Q.; Li, H.; Dai, T. Y.

    2016-04-01

    In this paper, we report a continuous-wave mode-locked Ho:YAP laser for the first time to our knowledge. Mode-locked pulse was produced by using an acousto-optic modulator. A 1.91-μm Tm-fiber laser as the pump source, at incident pump power of 25.9 W, the maximum output power of 2.87 W at 2117.8 nm was achieved in continuous-wave mode-locked regime. Pulse as short as 254.8 ps was obtained at repetition frequency of 81.52 MHz. In addition, the beam quality factor M 2 value of 1.6 was obtained.

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

    DOE PAGESBeta

    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-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

  18. Reversal of HO-1 related cytoprotection with increased expression is due to reactive iron.

    PubMed

    Suttner, D M; Dennery, P A

    1999-10-01

    It is often postulated that the cytoprotective nature of heme oxygenase (HO-1) explains the inducible nature of this enzyme. However, the mechanisms by which protection occurs are not verified by systematic evaluation of the physiological effects of HO. To explain how induction of HO-1 results in protection against oxygen toxicity, hamster fibroblasts (HA-1) were stably transfected with a tetracycline response plasmid containing the full-length rat HO-1 cDNA construct to allow for regulation of gene expression by varying concentrations of doxycycline (Dox). Transfected cells were exposed to hyperoxia (95% O(2)/5% CO2) for 24 h and several markers of oxidative injury were measured. With varying concentrations of Dox, HO activity was regulated between 3- and 17-fold. Despite cytoprotection with low (less than fivefold) HO activity, high levels of HO-1 expression (greater than 15-fold) were associated with significant oxygen cytotoxicity. Levels of non-heme reactive iron correlated with cellular injury in hyperoxia whereas lower levels of heme were associated with cytoprotection. Cellular levels of cyclic GMP and bilirubin were not significantly altered by modification of HO activity, precluding a substantial role for activation of guanylate cyclase by carbon monoxide or for accumulation of bile pigments in the physiological consequences of HO-1 overexpression. Inhibition of HO activity or chelation of cellular iron prior to hyperoxic exposure decreased reactive iron levels in the samples and significantly reduced oxygen toxicity. We conclude that there is a beneficial threshold of HO-1 overexpression related to the accumulation of reactive iron released in the degradation of heme. Therefore, despite the ready induction of HO-1 in oxidant stress, accumulation of reactive iron formed makes it unlikely that exaggerated expression of HO-1 is a cytoprotective response. PMID:10506583

  19. Reactive Ni/Ti nanolaminates

    SciTech Connect

    Adams, D. P.; Bai, M. M.; Rodriguez, M. A.; McDonald, J. P.; Jones, E. Jr.; Brewer, L.; Moore, J. J.

    2009-11-01

    Nickel/titanium nanolaminates fabricated by sputter deposition exhibited rapid, high-temperature synthesis. When heated locally, self-sustained reactions were produced in freestanding Ni/Ti multilayer foils characterized by average propagation speeds between approx0.1 and 1.4 m/s. The speed of a propagating reaction front was affected by total foil thickness and bilayer thickness (layer periodicity). In contrast to previous work with compacted Ni-Ti powders, no preheating of Ni/Ti foils was required to maintain self-propagating reactions. High-temperature synthesis was also stimulated by rapid global heating demonstrating low ignition temperatures (T{sub ig})approx300-400 deg. C for nanolaminates. Ignition temperature was influenced by bilayer thickness with more coarse laminate designs exhibiting increased T{sub ig}. Foils reacted in a vacuum apparatus developed either as single-phase B2 cubic NiTi (austenite) or as a mixed-phase structure that was composed of monoclinic B19{sup '} NiTi (martensite), hexagonal NiTi{sub 2}, and B2 NiTi. Single-phase, cubic B2 NiTi generally formed when the initial bilayer thickness was made small.

  20. The impact of clouds on radical concentrations: Observations of OH and HO2 during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Whalley, L. K.; George, I. J.; Stone, D.; Heard, D. E.

    2011-12-01

    Clouds play a crucial role in the chemistry of the atmosphere, occupying, on average, ~ 15 % of the volume of the lower atmosphere (Lelieveld & Crutzen, 1990). Modelling studies have shown that aqueous phase chemistry in clouds can influence gas phase radical chemistry and in turn can cause significant reductions in the oxidative capacity (e.g. Lelieveld & Crutzen, 1991; Kreidenweis et al., 2003) and, hence, removal rate of VOCs. A number of aircraft projects have identified significantly reduced HO2 concentrations when flying through clouds that exceeds the depletion expected due to the reduction in radiation alone (Olson et al., 2004; Commane et al., 2010). These experimental observations are relatively sparse, however, and until recently a comprehensive study to validate model predictions has been lacking. Here we report preliminary measurements of OH and HO2 radicals made during the HCCT (Hill Cap Cloud Thuringia) project that took place at Mt. Schmücke, Thuringia in Germany during September/October 2010. The University of Leeds Fluorescence Assay by Gas Expansion (FAGE) instrument was located at the summit of Mt. Schmücke and made near-continuous measurements of the radicals at the top of a 22 m tower. The site was regularly influenced by clouds throughout the measurement period and co-located measurements of liquid water content were made at the site enabling the influence of this microphysical parameter on the radical budget to be determined. On average, the photolysis rate of O3 to form O(1D), the primary daytime source of HOx radicals, was ~ 65 % lower in-cloud relative to the out of cloud observations. The HO2 concentrations were significantly depleted in cloud, with concentrations ~ 90 % lower relative to the out of cloud observations; an OH signal above the noise of the instrument was not observed during cloud events. These results suggest that heterogeneous processes in clouds do perturb the gas-phase radical chemistry. Further investigations into

  1. Simultaneous, in situ measurements of OH, HO2, O3, and H2O - A test of modeled stratospheric HO(x) chemistry

    NASA Technical Reports Server (NTRS)

    Wennberg, P. O.; Stimpfle, R. M.; Weinstock, E. M.; Dessler, A. E.; Lloyd, S. A.

    1990-01-01

    Simultaneous, in situ measurements of OH, HO2, H2O, and O3 from 37-23 km are reported. The partitioning between OH and HO2 and the total HO(x) concentration are compared with expected steady-state values. The ratio of HO2 to OH varies from less than 2 at 36 km to more than 3 at 25 km; in the lower stratosphere this ratio is nearly a factor of two less than predicted. The data are used to calculate HO(x) production and loss rates. The measured HO(x) mixing ratio is consistent with production dominated by the reaction of O(1D) with H2O, and loss controlled by NOy below 28 km and HO(x) above 30 km. The steady-state concentration of H2O2 is inferred from the measured HO2 concentration and calculated photolysis rate. The maximum H2O2 mixing ratio (at 33 km) is predicted to be less than 0.2 ppb.

  2. Registration of Three High Fiber Sugar Cane Varieties, L 79-1002, HoCP 91-552 AND Ho 00-961, for Biofuels Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High fiber sugarcane (Saccharum spp. hybrids) varieties, or energy canes, have been shown to be a viable feedstock for biofuel applications. Three high fiber sugarcane varieties, L 79-1002, HoCP 91-552 and Ho 00-961, were released in April 2007 for commercial biofuel production. L 79-1002 averaged 2...

  3. 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.

  4. 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.

  5. Interdiffusion in the Ni/TD-NiCr and Cr/TD-NiCr systems

    NASA Technical Reports Server (NTRS)

    Pawar, A. V.; Tenney, D. R.

    1974-01-01

    The diffusion of Ni and Cr into TD-NiCr has been studied over the 900 to 1100 C temperature range. The diffusion couples were prepared by electroplating Cr and Ni on polished TD-NiCr wafers. Concentration profiles produced as a result of isothermal diffusion at 905, 1000, and 1100 C were determined by electron microprobe analysis. The Boltzmann-Matano analysis was used to determine concentration-dependent diffusion coefficients which were found to compare favorably with previously reported values. These data suggest that 2 vol % ThO2 distribution has no appreciable effect on the rates of diffusion in TD-NiCr with a large grain size. This supports the view that an inert dispersoid in an alloy matrix will not in itself lead to enhanced diffusion unless a short-circuit diffusion structure is stabilized.

  6. 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.

  7. 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.

  8. Observations of nitrous acid (HONO) and peroxynitric acid (HO2NO2) made during the 2013 and 2014 Uintah Basin Winter Ozone Study (UBWOS)

    NASA Astrophysics Data System (ADS)

    Veres, P. R.; Roberts, J. M.; Alvarez, S. L.; Brown, S. S.; Burkholder, J. B.; De Gouw, J. A.; Edwards, P. M.; Lefer, B. L.; Liggio, J.; Min, K. E.; Stutz, J.; Tsai, J. Y.; Colosimo, S. F.; Wentzell, J. J. B.; Wild, R. J.; Yuan, B.; Flynn, J. H., III

    2014-12-01

    HONO is frequently observed to be the main OH source in the early morning, with more recent urban measurements showing significant rates of daytime production. Quantifying the impact of HONO as a source of daytime oxidant is crucial to forming a more explicit understanding of tropospheric ozone formation. In this work, ambient observations of HONO were made during the 2013 and 2014 Uintah Basin Wintertime Ozone Study (UBWOS) at a field site in Utah using various analytical techniques including chemical ionization mass spectrometry (CIMS), differential optical absorption spectroscopy (DOAS), cavity enhanced absorption spectroscopy (CEAS), and long path absorption photometry (LOPAP). Observations of HONO and HO2NO2 will be presented and compared to model results using a chemical box model applying explicit MCM chemistry to describe an ozone formation event observed during the 2013 wintertime season. Strong inversions leading to a build-up of many primary and secondary pollutants as well as low temperatures drove daytime HO2NO2 observations as high as 1.5 ppbv during the 2013 study. The potential of these high HO2NO2 concentrations as an interference to the various HONO measurements techniques will be discussed. Daytime HONO observations will be presented and analyzed with respect to coinciding vertical gradients, sampling artifacts, and potential instrumental interferences.

  9. NSAIDs inhibit neovascularization of choroid through HO-1-dependent pathway.

    PubMed

    Yoshinaga, Narimasa; Arimura, Noboru; Otsuka, Hiroki; Kawahara, Ko-Ichi; Hashiguchi, Teruto; Maruyama, Ikuro; Sakamoto, Taiji

    2011-09-01

    Intraocular neovascularization is the leading cause of severe visual loss and anti-vascular endothelial growth factor (VEGF) therapy is currently performed for choroidal neovascularization (CNV). Despite its potent anti-angiogenic effect, there are concerns about its long-term safety. Non-steroidal anti-inflammatory drugs (NSAIDs) are common therapeutic agents used for treating inflammatory diseases, and their anti-stress effects are attracting attention now. We studied the effects of topical NSAIDs on CNV, focusing on anti-stress proteins. Cultured retinal pigment epithelium (RPE) cells were treated with NSAIDs: bromfenac, indomethacin, or vehicle control. Transcription factor NF-E2-related factor 2 (Nrf2) and its downstream anti-oxidant protein heme oxygenase (HO)-1 were assessed using western blot and immunohistochemistry. As a result, NSAIDs induced translocation of Nrf2 into the nucleus and the robust expression of HO-1 in a dose- and time-dependent manner. Flow cytometric analysis revealed that bromfenac inhibited H(2)O(2)-induced apoptosis in cultured RPE cells. Next, we studied the effects of topical bromfenac on laser-induced CNV model in rat. The expressions of Nrf2 and HO-1, infiltrations of ED-1-positive macrophages at CNV lesions and size were analyzed. VEGF in the ocular fluid of these rats was also measured using enzyme-linked immunosorbent assay. Rats administered an inhibitor of HO-1 stannic mesoporphyrin (SnMP) were also studied. The results showed that topical bromfenac led to translocation of Nrf2 and induction of HO-1 in CNV lesions and that the number of infiltrating macrophages at the CNV lesion decreased. The sizes of CNV lesions were significantly smaller in bromfenac-treated rats than control CNV, and the effects were diminished by SnMP. VEGF increased in the ocular fluid after laser treatment and was inhibited by bromfenac and SnMP canceling these effects. NSAIDs inhibit CNV through the novel anti-stress protein HO-1-dependent pathway

  10. 1.6-W self-referenced frequency comb at 2.06 μm using a Ho:YLF multipass amplifier.

    PubMed

    Coluccelli, Nicola; Gambetta, Alessio; Gatti, Davide; Marangoni, Marco; Di Lieto, Alberto; Tonelli, Mauro; Galzerano, Gianluca; Laporta, Paolo

    2011-06-15

    A high-power optical frequency comb at 2.06 μm has been generated using a Ho:YLF multipass amplifier seeded by the long wavelength supercontinuum tail of an octave-spanning Er:fiber comb source. The Ho:YLF amplifier showed a net gain larger than 30 dB from 2048 to 2068 nm, allowing the generation of a 20 nm bandwidth comb with a mode spacing of 100 MHz and a power per mode ranging from 20 to 370 μW. In the time domain, the amplified comb corresponds to a pulse train with 1.6 W total power and 508 fs transform-limited pulse duration. Using a self-referencing f-2f interferometer and a phase-locking loop, spectral narrowing of the offset frequency down to less than 17 Hz has been achieved. PMID:21685999

  11. Over-expression of HO-1 on mesenchymal stem cells promotes angiogenesis and improves myocardial function in infarcted myocardium

    PubMed Central

    2010-01-01

    Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with diverse cytoprotective effects, and reported to have an important role in angiogenesis recently. Here we investigated whether HO-1 transduced by mesenchymal stem cells (MSCs) can induce angiogenic effects in infarcted myocardium. HO-1 was transfected into cultured MSCs using an adenoviral vector. 1 × 106 Ad-HO-1-transfected MSCs (HO-1-MSCs) or Ad-Null-transfected MSCs (Null-MSCs) or PBS was respectively injected into rat hearts intramyocardially at 1 h post-myocardial infarction. The results showed that HO-1-MSCs were able to induce stable expression of HO-1 in vitro and in vivo. The capillary density and expression of angiogenic growth factors, VEGF and FGF2 were significantly enhanced in HO-1-MSCs-treated hearts compared with Null-MSCs-treated and PBS-treated hearts. However, the angiogenic effects of HO-1 were abolished by treating the animals with HO inhibitor, zinc protoporphyrin. The myocardial apoptosis was marked reduced with significantly reduced fibrotic area in HO-1-MSCs-treated hearts; Furthermore, the cardiac function and remodeling were also significantly improved in HO-1-MSCs-treated hearts. Our current findings support the premise that HO-1 transduced by MSCs can induce angiogenic effects and improve heart function after acute myocardial infarction. PMID:20925964

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

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Suto, M.

    1986-01-01

    Research for the period from December 1, 1985 to May 31, 1986 is discussed, i.e., the reaction rate constant of HO2+O3 has been measured with a discharge-flow-tube apparatus. The HO2 radical was detected by the OH(A-X) photofragment emission produced from photodissociative excitation of HO2 at 147 nm. In the meantime, the optical emissions produced by the vacuum ultraviolet excitation of chemical species in the flow tube were investigated and used to examine the possibility for their interference with the HO2 detection. The research results are summarized below.

  13. [hHO-1 structure prediction and its mutant construct, expression, purification and activity analysis].

    PubMed

    Xia, Zhen Wei; Cui, Wen Jun; Zhou, Wen Pu; Zhang, Xue Hong; Shen, Qing Xiang; Li, Yun Zhu; Yu, Shan Chang

    2004-10-01

    Human Heme Oxygenase-1 (hHO-1) is the rate-limiting enzyme in the catabolism reaction of heme, which directly regulates the concentration of bilirubin in human body. The mutant structure was simulated by Swiss-pdbviewer procedure, which showed that the structure of active pocket was changed distinctly after Ala25 substituted for His25 in active domain, but the mutated enzyme still binded with heme. On the basis of the results, the expression vectors, pBHO-1 and pBHO-1(M), were constructed, induced by IPTG and expressed in E. coli DH5alpha strain. The expression products were purified with 30%-60% saturation (NH4)2SO4 and Q-Sepharose Fast Flow column chromatography. The concentration of hHO-1 in 30%-60% saturation (NH4)2SO4 components and in fractions through twice column chromatography was 3.6-fold and 30-fold higher than that in initial product, respectively. The activity of wild hHO-1 (whHO-1) and mutant hHO-1 (deltahHO-1) showed that the activity of deltahHO-1 was reduced 91.21% compared with that of whHO-1. The study shows that His25 is of importance for the mechanism of hHO-1, and provides the possibility for effectively regulating the activity to exert biological function. PMID:15636365

  14. 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.

  15. 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.

  16. Nuclear sources in galaxies

    NASA Astrophysics Data System (ADS)

    Elvis, M.

    In the local Universe most massive black holes at the centers of galaxies are not luminous quasars. Is this because (1) they are starved of gas, (2) they accrete without emitting radiation, (3) they refuse to eat, ejecting the incoming material, or (4) they are storing up matter in an accretion disk to feast later?With Chandra ACIS we have imaged a pilot sample of 6 nearby (D 30 Mpc) elliptical galaxies chosen to be especially quiescent based on the careful optical spectroscopy of Ho, measured black hole masses (Mbh > 10(7)Msol), and with existing X-ray upper limits (Lx 10(40)erg/s) implying far sub-Eddington accretion. In these galaxies we can measure, or limit, the diffuse hot interstellar medium, and so constrain the Bondi accretion rate.Faint X-ray emission is detected at or around the nucleus in each galaxy. The morphology of these weak X-ray sources is complex. The X-ray colors of the sources can be determined, and a moderate quality spectrum for one was obtained. We discuss these results against the possible explanations of black hole quiescence.On the other hand, a few percent of all galaxies shows evidence for nuclear activity and a brief review of the high energy emission from Active Galactic Nuclei is given.

  17. Solar-pumped Er,Tm,Ho:YAG laser

    SciTech Connect

    Benmair, R.M.J.; Kagan, J.; Kalisky, Y.; Noter, Y.; Oron, M.; Shimony, Y.; Yogev, A. )

    1990-01-01

    Direct solar illumination was used to pump a 5-mm-diameter 62-mm exposed-length rod of Er,Tm,Ho:YAG to achieve a quasi-cw lasing of the Ho ion at an average power of 12 W. The solar radiation was chopped at a 20% duty cycle to avoid overloading of the cooling system. The peak power output was more than 65 W during the chopper's open times. The slope efficiency is 3.8%, and the threshold input energy is approximately 100 W. The laser was operated for long times (up to hours) while maintaining its performance. This is, to our knowledge, the first directly solar-pumped laser operating at 77 K.

  18. Cathodoluminescence of GaN implanted with Sm and Ho

    SciTech Connect

    Lozykowski, H.J.; Jadwisienczak, W.M.; Brown, I.

    1999-04-01

    We report the first observation of visible cathodoluminescence of the rare earth (RE) elements Sm, Ho implanted in GaN. The implanted samples were given isochronal thermal annealing treatments at a temperature of 1100 degrees C in N2, at atmospheric pressure to recover implantation damages and activate the RE ions. The sharp characteristic emission lines corresponding to Sm{sup 3+} and Ho{sup 3+} intra-4f{sup n}-shell transitions are resolved in the spectral range from 400 to 1000 nm, and observed over the temperature range of 11-411 K. The cathodoluminescence emission is only weakly temperature dependent. The results indicate that RE doped GaN epilayers are suitable as a material for visible optoelectronic devices.

  19. 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. PMID:27391747

  20. 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.

  1. Holographic superconductors with Hořava-Lifshitz black holes

    NASA Astrophysics Data System (ADS)

    Cai, Rong-Gen; Zhang, Hai-Qing

    2010-03-01

    We discuss the phase transition of planar black holes in Hořava-Lifshitz gravity by introducing a Maxwell field and a complex scalar field. We calculate the condensate of the charged operators in the dual conformal field theories when the mass square of the complex scalar field is m2=-2/L2 and m2=0, respectively. We compute the electrical conductivity of the Hořava-Lifshitz superconductor in the probe approximation. In particular, it is found that there exists a spike in the conductivity for the case of the operator with scaling dimension one. These results are quite similar to those in the case of Schwarzschild-AdS black holes, which demonstrates that the holographic superconductivity is a robust phenomenon associated with asymptotic AdS black holes.

  2. Thermochemical stability of the HO 2-HOCl complex

    NASA Astrophysics Data System (ADS)

    Jalbout, A. F.; Li, X. H.; Solimannejad, M.

    2006-03-01

    The Van der Waals complex between hydroperoxy radical (HO 2) and hypochlorous acid (HOCl) has been studied using the B3LYP density functional theory method, the second-order Moller-Plessett level of theory, as well as the coupled-cluster method (CCSD(T)) with basis sets as large as 6-311++G(3df, 3pd). Our calculations show stabilization energies for HO 2-HOCl of 4.83, 5.03, 4.64, and 5.28 kcal/mol at the B3LYP/6-311++G(3df, 3pd), MP2/6-311++G(3df, 3pd), CCSD(T)/6-311++G(3df, 3pd) and G2 levels of theory, respectively.

  3. 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.

  4. The reactions of HO2 with CO and NO and the reaction of O(1D) with H2O

    NASA Technical Reports Server (NTRS)

    Simonaitis, R.; Heicklen, J.

    1973-01-01

    HO2 radicals were generated by the photolysis of N2O at 2139 A in the presence of excess H2O or H2 and smaller amounts of CO and O2. The O(1D) atoms produced from the photolysis of N2O to give HO radicals or H2 to give HO + H. With H2O two HO radicals are produced for each O(1D) removed low pressures (i.e. approximately 20 torr H2O), but the HO yield drops as the pressure is raised. This drop is attributed to the insertion reaction: O(1D) + H2O + M yields H2O2 +M. The HO radicals generated can react with either CO or H2 to produce H atoms which then add to O2 to produce HO2. Two reactions are given for the reactions of the HO radicals, in the absence of NO.

  5. 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.

  6. 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.

  7. 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.

  8. [Observational study on urinary status following HoLEP].

    PubMed

    Kono, Yuka; Matsumoto, Keiyu; Masuda, Norihiko; Shiraishi, Yusuke; Negoro, Hiromitsu; Utsunomiya, Noriaki; Tsunemori, Hiroyuki; Okubo, Kazutoshi; Okada, Takuya; Segawa, Takehiko; Muguruma, Koei; Kawakita, Mutsushi

    2014-02-01

    We assessed the safety, and postoperative urinary status of holmium laser enucleation of the prostate (HoLEP) for the treatment of benign prostatic hyperplasia (BPH). Of the initial 117 patients who underwent HoLEP from November 2004 to March 2011, 49 were followed up for two yearsor longer. These 49 patients were evaluated once preoperatively, and at the 3rd, 6th, 12th, 24th, 48th, and 60th month postoperatively using International Prostate Symptom Scores (I-PSS) total and sub-score, quality of life score (QOL), maximum flow rate (Qmax), and post-voiding residual urine volume (PVR). The median estimated transition zone and enucleated volume were 45. 1 and 47. 9 g, respectively. Evaluation scores showed significant improvementsthroughout the follow-up. I-PSS total scoresimproved from 21 points(before surgery) to 6 points(12 monthsafter surgery), QOL scoresimproved from 5 pointsto 2 points, Qmax improved from 6.8 ml/s to 17.4 ml/s, and PVR improved from 101 ml to 26 ml, respectively. Transient urinary incontinence was noted in 14 patients (28.5%). One case showed a Clavien grade 3 complication of postoperative bleeding. No blood transfusion or re-surgery for BPH was required. In conclusion, HoLEP proved to be a safe and effective therapy, with potential to become a new gold standard for treating BPH. PMID:24755814

  9. Non-coding RNA derived from the region adjacent to the human HO-1 E2 enhancer selectively regulates HO-1 gene induction by modulating Pol II binding

    PubMed Central

    Maruyama, Atsushi; Mimura, Junsei; Itoh, Ken

    2014-01-01

    Recent studies have disclosed the function of enhancer RNAs (eRNAs), which are long non-coding RNAs transcribed from gene enhancer regions, in transcriptional regulation. However, it remains unclear whether eRNAs are involved in the regulation of human heme oxygenase-1 gene (HO-1) induction. Here, we report that multiple nuclear-enriched eRNAs are transcribed from the regions adjacent to two human HO-1 enhancers (i.e. the distal E2 and proximal E1 enhancers), and some of these eRNAs are induced by the oxidative stress-causing reagent diethyl maleate (DEM). We demonstrated that the expression of one forward direction (5′ to 3′) eRNA transcribed from the human HO-1 E2 enhancer region (named human HO-1enhancer RNA E2-3; hereafter called eRNA E2-3) was induced by DEM in an NRF2-dependent manner in HeLa cells. Conversely, knockdown of BACH1, a repressor of HO-1 transcription, further increased DEM-inducible eRNA E2-3 transcription as well as HO-1 expression. In addition, we showed that knockdown of eRNA E2-3 selectively down-regulated DEM-induced HO-1 expression. Furthermore, eRNA E2-3 knockdown attenuated DEM-induced Pol II binding to the promoter and E2 enhancer regions of HO-1 without affecting NRF2 recruitment to the E2 enhancer. These findings indicate that eRNAE2-3 is functional and is required for HO-1 induction. PMID:25404134

  10. 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

  11. s-process nucleosynthesis in massive stars: new results on 60Fe, 62Ni and 64Ni

    NASA Astrophysics Data System (ADS)

    Domingo-Pardo, C.; Dillmann, I.; Faestermann, T.; Giesen, U.; Görres, J.; Heil, M.; Horn, S.; Käppeler, F.; Köchli, S.; Korschinek, G.; Lachner, J.; Maiti, M.; Marganiec, J.; Neuhausen, J.; Nolte, R.; Poutivtsev, M.; Reifarth, R.; Rugel, R.; Schumann, D.; Uberseder, E.; Voss, F.; Walter, S.; Wiescher, M.

    2009-01-01

    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,γ) 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 60Fe, 62Ni and 64Ni are reported. 60Fe is mostly produced during the short convective C shell burning phase, where peak densities of ~1011 cm-3 are reached, prior to the SN explosion. The stellar (n,γ) cross section of 60Fe could be measured with a 1 μg 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 62Ni, whereas in this case, the number of 63Ni nuclei produced were determined via accelerator mass spectroscopy at the Maier-Leibnitz-Laboratorium in Garching/Munich. The (n,γ) cross section of 64Ni 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_TOF of CERN for the future campaign in 2009.

  12. Extratumoral Heme Oxygenase-1 (HO-1) Expressing Macrophages Likely Promote Primary and Metastatic Prostate Tumor Growth

    PubMed Central

    Adamo, Hanibal; Thysell, Elin; Jernberg, Emma; Stattin, Pär; Widmark, Anders; Wikström, Pernilla; Bergh, Anders

    2016-01-01

    Aggressive tumors induce tumor-supporting changes in the benign parts of the prostate. One factor that has increased expression outside prostate tumors is hemoxygenase-1 (HO-1). To investigate HO-1 expression in more detail, we analyzed samples of tumor tissue and peritumoral normal prostate tissue from rats carrying cancers with different metastatic capacity, and human prostate cancer tissue samples from primary tumors and bone metastases. In rat prostate tumor samples, immunohistochemistry and quantitative RT-PCR showed that the main site of HO-1 synthesis was HO-1+ macrophages that accumulated in the tumor-bearing organ, and at the tumor-invasive front. Small metastatic tumors were considerably more effective in attracting HO-1+ macrophages than larger non-metastatic ones. In clinical samples, accumulation of HO-1+ macrophages was seen at the tumor invasive front, almost exclusively in high-grade tumors, and it correlated with the presence of bone metastases. HO-1+ macrophages, located at the tumor invasive front, were more abundant in bone metastases than in primary tumors. HO-1 expression in bone metastases was variable, and positively correlated with the expression of macrophage markers but negatively correlated with androgen receptor expression, suggesting that elevated HO-1 could be a marker for a subgroup of bone metastases. Together with another recent observation showing that selective knockout of HO-1 in macrophages reduced prostate tumor growth and metastatic capacity in animals, the results of this study suggest that extratumoral HO-1+ macrophages may have an important role in prostate cancer. PMID:27280718

  13. Extratumoral Heme Oxygenase-1 (HO-1) Expressing Macrophages Likely Promote Primary and Metastatic Prostate Tumor Growth.

    PubMed

    Halin Bergström, Sofia; Nilsson, Maria; Adamo, Hanibal; Thysell, Elin; Jernberg, Emma; Stattin, Pär; Widmark, Anders; Wikström, Pernilla; Bergh, Anders

    2016-01-01

    Aggressive tumors induce tumor-supporting changes in the benign parts of the prostate. One factor that has increased expression outside prostate tumors is hemoxygenase-1 (HO-1). To investigate HO-1 expression in more detail, we analyzed samples of tumor tissue and peritumoral normal prostate tissue from rats carrying cancers with different metastatic capacity, and human prostate cancer tissue samples from primary tumors and bone metastases. In rat prostate tumor samples, immunohistochemistry and quantitative RT-PCR showed that the main site of HO-1 synthesis was HO-1+ macrophages that accumulated in the tumor-bearing organ, and at the tumor-invasive front. Small metastatic tumors were considerably more effective in attracting HO-1+ macrophages than larger non-metastatic ones. In clinical samples, accumulation of HO-1+ macrophages was seen at the tumor invasive front, almost exclusively in high-grade tumors, and it correlated with the presence of bone metastases. HO-1+ macrophages, located at the tumor invasive front, were more abundant in bone metastases than in primary tumors. HO-1 expression in bone metastases was variable, and positively correlated with the expression of macrophage markers but negatively correlated with androgen receptor expression, suggesting that elevated HO-1 could be a marker for a subgroup of bone metastases. Together with another recent observation showing that selective knockout of HO-1 in macrophages reduced prostate tumor growth and metastatic capacity in animals, the results of this study suggest that extratumoral HO-1+ macrophages may have an important role in prostate cancer. PMID:27280718

  14. Methoxylated PBDEs (MeO-PBDEs), hydroxylated PBDEs (HO-PBDEs) and hydroxylated PCBs (HO-PCBs) in the liver of harbor seals from the northwest Atlantic.

    PubMed

    Weijs, Liesbeth; Shaw, Susan D; Berger, Michelle L; Neels, Hugo; Blust, Ronny; Covaci, Adrian

    2014-09-15

    Metabolites of PCBs and PBDEs are shown to influence the thyroid hormone homeostasis and therefore, could have an influence on the growth of newborn or young animals. We have investigated the occurrence of hydroxylated PCBs (HO-PCBs), hydroxylated PBDEs (HO-PBDEs), and methoxylated PBDEs (MeO-PBDEs) in the liver (48 pups; 6 adults) and blubber (4 pups; 1 adult) of harbor seals (Phoca vitulina concolor) from the northwest Atlantic. The sum of HO-PCBs in the liver ranged from 90 to 22,450 pg/g wet weight (ww) for pups and from 410 to 5290 pg/g ww for adults. Congener 4-HO-CB 107 was predominant in almost all samples regardless of age or gender, except in one adult male. Sum HO-PCB concentrations were highly correlated with the sum of precursor PCBs in the liver of harbor seals (r(2) = 0.79; p<0.0001). Concentrations of sum HO-PBDEs in the liver ranged from 70 to 1850 pg/g ww for pups and from 90 to 230 pg/g ww for adults. HO-PBDEs were also correlated with PBDEs (r(2) = 0.58; p<0.0001). Sum MeO-PBDE concentrations in the liver ranged from 20 to 1460 pg/g ww in pups and from 10 to 270 pg/g ww in adults. HO-PCBs and HO-PBDEs were not detected in the blubber. Levels of MeO-PBDEs in the blubber ranged from 1500 to 4400 pg/g ww. In all blubber samples, 6-MeO-BDE 47 was the predominant MeO-PBDE congener, followed by 2'-MeO-BDE 68 and 5-MeO-BDE 47, respectively. The presence of HO-metabolites in pup liver suggests that young harbor seals may have some, yet limited, metabolic capacity for PCBs and PBDEs, which can lead to an excessive accumulation of these chemicals in the body. Moreover, the presence of HO-PCB and HO-PBDE metabolites may pose an additional stress for young harbor seals due to their influence on the thyroid hormone system and could have consequences for the entire population. PMID:24982026

  15. 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.

  16. Increased HO-1 Levels Ameliorate Fatty Liver Development Through a Reduction of Heme and Recruitment of FGF21

    PubMed Central

    Hinds, Terry D.; Sodhi, Komal; Meadows, Charles; Fedorova, Larisa; Puri, Nitin; Kim, Dong Hyun; Peterson, Stephen J.; Shapiro, Joseph; Abraham, Nader G.; Kappas, Attallah

    2013-01-01

    Objective Obese leptin deficient (ob/ob) mice are a model of adiposity that displays increased levels of fat, glucose and liver lipids. Our hypothesis is that HO-1 overexpression ameliorates fatty liver development. Design and Methods Obese mice were administered cobalt protoporphyrin (CoPP) and stannic mesoporphyrin (SnMP) for 6 weeks. Heme, HO-1, HO activity, PGC1α, FGF21, glycogen content and lipogenesis were assessed. Results CoPP administration increased hepatic HO-1 protein levels and HO activity, decreased hepatic heme, body weight gain, glucose levels and resulted in decreased steatosis. Increased levels of HO-1 produced a decrease in lipid droplet size, FAS levels involving recruitment of FGF21, PPARα and Glut 1. These beneficial effects were reversed by inhibition of HO activity. Conclusion Increased levels of HO-1 and HO activity reduced the levels of obesity by reducing hepatic heme and lipid accumulation. These changes were manifested by decreases in cellular heme, increases in FGF21, glycogen content and fatty liver. The beneficial effect of HO-1 induction results from an increase in PPARα and FGF21 levels and a decrease in PGC1α, levels they were reversed by SnMP. Low levels of HO-1 and HO activity are responsible for fatty liver. PMID:23839791

  17. 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.

  18. 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)

  19. Behavior of Ni, Zn and Cr during low temperature aqueous Fe oxidation processes on Mars

    NASA Astrophysics Data System (ADS)

    Zhao, Yu-Yan S.; McLennan, Scott M.

    2013-05-01

    The behavior of Ni(II), Zn(II) and Cr(III) during the melanterite (FeSO4·7H2O) to hematite (α-Fe2O3) oxidative transformations involving evolution pathways via jarosite ((H3O,K)Fe3(OH)6(SO4)2), schwertmannite (Fe8O8(OH)6(SO4)) and goethite (α-FeOOH) were investigated in an acidic saturated MgSO4 matrix. Results provide important clues about how elevated levels of trace elements are incorporated into the secondary Fe mineralogy assemblages found on Mars and the mechanism for formation of hematitic concretions at Meridiani Planum on Mars. Our results demonstrate that starting at the same concentrations in the initial solution, final amounts of Ni, Zn and Cr in hematite via different pathways are very different. In Path 1 (melanterite → jarosite → hematite), partitioning of Ni, Zn and Cr into jarosite and hematite (formed through dissolution of jarosite) is most likely in the order: Cr > Zn > Ni. In Path 2 (melanterite → schwertmannite → goethite → hematite), schwertmannite and goethite exhibited strong affinities for divalent Ni and Zn. During such a pathway, Ni should accumulate more than Zn by at least a factor of two, and partitioning of Ni, Zn and Cr to the hematite is most likely in the order: Cr > Ni > Zn. Therefore, our results suggest that the high Ni and moderate Zn distribution pattern observed in Meridiani hematitic spherule-bearing samples can be explained best by the schwertmannite-goethite to hematite pathway (Path 2), without need for an additional high Ni source in this region. Although the lack of goethite at Meridiani renders it uncertain if goethite ever served as a precursor to facilitate hematite formation, dehydration of nano-crystalline goethite is thermodynamically favored and cannot be ruled out. On the other hand, if hematitic concretions were formed by dissolution of jarosite (Path 1), then much higher initial Ni/Zn ratios than 1 in initial diagenetic fluids may be necessary to explain the elevated levels of Ni in the spherules

  20. Telegram from Ho Chi Minh to Harry S. Truman. Teaching with Documents.

    ERIC Educational Resources Information Center

    Potter, Lee Ann; Schamel, Wynell

    2000-01-01

    Focuses on a telegram sent from Hanoi, Vietnam, by Ho Chi Minh through the Office of Strategic Services (OSS) station in Kunming, China, to President Truman in which Ho asked for support of Vietnam's independence from France. Provides background information, a reproduction of the telegram, and ideas for teaching activities. (CMK)

  1. 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...

  2. 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...

  3. Lentivirus mediated HO-1 gene transfer enhances myogenic precursor cell survival after autologous transplantation in pig.

    PubMed

    Laumonier, Thomas; Yang, Sheng; Konig, Stephane; Chauveau, Christine; Anegon, Ignacio; Hoffmeyer, Pierre; Menetrey, Jacques

    2008-02-01

    Cell therapy for Duchenne muscular dystrophy and other muscle diseases is limited by a massive early cell death following injections. In this study, we explored the potential benefit of heme oxygenase-1 (HO-1) expression in the survival of porcine myogenic precursor cells (MPCs) transplanted in pig skeletal muscle. Increased HO-1 expression was assessed either by transient hyperthermia or by HO-1 lentiviral infection. One day after the thermic shock, we observed a fourfold and a threefold increase in HSP70/72 and HO-1 levels, respectively. This treatment protected 30% of cells from staurosporine-induced apoptosis in vitro. When porcine MPC were heat-shocked prior to grafting, we improved cell survival by threefold at 5 days after autologous transplantation (26.3 +/- 5.5% surviving cells). After HO-1 lentiviral transduction, almost 60% of cells expressed the transgene and kept their myogenic properties to proliferate and fuse in vitro. Apoptosis of HO-1 transduced cells was reduced by 50% in vitro after staurosporine induction. Finally, a fivefold enhancement in cell survival was observed after transplantation of HO-1-group (47.5 +/- 9.1% surviving cells) as compared to the nls-LacZ-group or control group. These results identify HO-1 as a protective gene against early MPC death post-transplantation. PMID:18026170

  4. Paracrine action of HO-1-modified mesenchymal stem cells mediates cardiac protection and functional improvement.

    PubMed

    Zeng, Bin; Ren, Xiaofeng; Lin, Guosheng; Zhu, Chengang; Chen, Honglei; Yin, Jiechao; Jiang, Hong; Yang, Bo; Ding, Danhua

    2008-10-01

    The aim has been to determine whether the supernatants of mesenchymal stem cells (MSCs) transfected with adenovirus carrying human heme oxygenase-1 (hHO-1) gene protect cardiomyocytes from ischemic injury. We have found that hHO-1 infected MSCs (hHO-1-MSCs) increased expression of hHO-1 protein. Apoptosis of cultured hHO-1-MSCs exposed to hypoxia was suppressed. Several cytokines, including HGF, bFGF, TGF-beta, VEGF and IL-1beta, were produced by hHO-1-MSCs, some being significantly enhanced under hypoxia stimulation. Meanwhile, those cytokines reduced caspase-3 level and activity in cultured adult rat ventricular cardiomyocytes (ARVCs) exposed to hypoxia. Supernatants obtained from hHO-1-MSCs improved left ventricular function, limited myocardial infarct size, increased microvessel density, and inhibited apoptosis of cardiomyocytes in rat myocardial infarction. It can be concluded hHO-1-modified MSCs prevent myocardial cell injury via secretion of paracrine-acting mediators. PMID:18692581

  5. HO-1-mediated macroautophagy: a mechanism for unregulated iron deposition in aging and degenerating neural tissues.

    PubMed

    Zukor, Hillel; Song, Wei; Liberman, Adrienne; Mui, Jeannie; Vali, Hojatollah; Fillebeen, Carine; Pantopoulos, Kostas; Wu, Ting-Di; Guerquin-Kern, Jean-Luc; Schipper, Hyman M

    2009-05-01

    Oxidative stress, deposition of non-transferrin iron, and mitochondrial insufficiency occur in the brains of patients with Alzheimer disease (AD) and Parkinson disease (PD). We previously demonstrated that heme oxygenase-1 (HO-1) is up-regulated in AD and PD brain and promotes the accumulation of non-transferrin iron in astroglial mitochondria. Herein, dynamic secondary ion mass spectrometry (SIMS) and other techniques were employed to ascertain (i) the impact of HO-1 over-expression on astroglial mitochondrial morphology in vitro, (ii) the topography of aberrant iron sequestration in astrocytes over-expressing HO-1, and (iii) the role of iron regulatory proteins (IRP) in HO-1-mediated iron deposition. Astroglial hHO-1 over-expression induced cytoplasmic vacuolation, mitochondrial membrane damage, and macroautophagy. HO-1 promoted trapping of redox-active iron and sulfur within many cytopathological profiles without impacting ferroportin, transferrin receptor, ferritin, and IRP2 protein levels or IRP1 activity. Thus, HO-1 activity promotes mitochondrial macroautophagy and sequestration of redox-active iron in astroglia independently of classical iron mobilization pathways. Glial HO-1 may be a rational therapeutic target in AD, PD, and other human CNS conditions characterized by the unregulated deposition of brain iron. PMID:19250338

  6. 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.

  7. Nonvacuum Deposition of Silver Doped YBCO Coated Conductor on %100 Lattice Match Buffered Ni Tapes

    NASA Astrophysics Data System (ADS)

    Arda, L.; Cakiroglu, O.; Keskin, S.; Sacli, O. A.

    2007-04-01

    Silver doped YBa2Cu3O7-δ (YBCO) coated conductors were fabricated on Gd1.624Ho0.376O3 (100 % lattice match with YBCO) textured buffer layers on Ni tape by reel-to-reel sol-gel dip coating system. Sample were prepared with different wt(1-5) % Ag doped ratio. The surface morphologies and microstructure of all sample were characterized by ESEM, EDS and XRD. Pole figure texture analyses have been done to characterize texture of buffer layer and YBCO superconducting film . The critical current Ic measurement was performed using four wire method with the 1 μV/cm criterion. The critical current density, Jc was measured to be 2.2 × 104 A/cm2 at 77 K self field for 1 wt % Ag doped YBCO sample.

  8. Magnetic structure of TbNi{sub 2}B{sub 2}C

    SciTech Connect

    Dervenagas, P.; Zarestky, J.; Stassis, C.; Goldman, A.I.; Canfield, P.C.; Cho, B.K.

    1996-04-01

    Neutron-diffraction techniques have been used to study the magnetic structure of TbNi{sub 2}B{sub 2}C. The measurements, performed on single crystals of this compound, show that below approximately 15 K the moments order in an almost longitudinal spin wave with wave vector along {ital a}{sup {asterisk}}. The magnitude of the wave vector is close to that obtained in the Ho, Er, and Gd compounds. This observation provides additional evidence that there are common Fermi-surface nesting features along {ital a}{sup {asterisk}} in the rare-earth nickel boride carbides which cause the magnetic ordering of the rare-earth moments via the Ruderman-Kittel-Kasuya-Yosida mechanism. Below approximately 8 K, the experimental results indicate the development of a small ferromagnetic component. {copyright} {ital 1996 The American Physical Society.}

  9. 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)

  10. 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).

  11. Magnetic properties of NiFe2O4/carbon nanofibers from Venezuelan petcoke

    NASA Astrophysics Data System (ADS)

    Briceño, Sarah; Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi; Cañizales, Edgard

    2015-05-01

    NiFe2O4/carbon nanofibers (NiFe2O4/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe2O4 as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe2O4/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs.

  12. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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.

  14. 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

    2015-01-01

    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 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. PMID:26567536

  15. Preparation and bioevaluation of 166Ho labelled hydroxyapatite (HA) particles for radiosynovectomy.

    PubMed

    Unni, P R; Chaudhari, P R; Venkatesh, Meera; Ramamoorthy, N; Pillai, M R A

    2002-02-01

    The preparation of 166Ho labeled hydroxy apatite (HA) particles for radiosynovectomy applications is described in this paper. 166Ho was prepared by the irradiation of Ho2O3 at a flux of 1.8 x 10(13) neutrons/cm2/s for about 7 days. The irradiation resulted in the production of approximately 17 GBq of 166Ho activity at the end of six hours post end of bombardment and the corresponding specific activity was approximately 3-4 GBq/mg of Ho. The irradiated target was dissolved in 0.1 N HCl solution. Radionuclidic purity was ascertained by high resolution gamma ray spectrometry. HA particles were synthesized and characterized by X-ray diffractometry. Labeling studies were carried out with and without citric acid as a transchelating agent. Radiochemical yield and purity of the 166Ho-HA particles were ascertained by paper chromatography and by paper electrophoresis techniques. Labeling yield of >98% could be achieved at pH 7, with 40 mg of HA particles and 8.6 microg of Ho. 166Ho-HA particles prepared were stable for 72 h. Bio-evaluation of the 166Ho -HA particles were carried out by injecting approximately 74 MBq dose in 200 microL (approximately 8 mg of 166Ho-HA particles) directly into the arthritis induced knee joints as well as into the healthy knee joints of white New Zealand rabbits. Images of the injected joints of the animals recorded using a gamma camera at regular intervals showed good retention. Blood samples were collected from the animals and activity assayed in a scintillation detector. Experiments were also carried out under identical conditions in normal rabbits. In both the cases, it was observed that there was no significant extra articular leakage of the injected activity over the study period of 96 h post injection. PMID:11823125

  16. Kinetics of hydroperoxy radical reactions with acetone/HO2 adduct and with acetonylperoxy radical

    NASA Astrophysics Data System (ADS)

    Grieman, F. J.; VanDerGeest, K.; Newenhouse, E.; Watkins, K.; Noell, A. C.; Hui, A.; Sander, S. P.; Okumura, M.

    2013-12-01

    Reactions of hydroperoxy radical, HO2, with acetone and with acetonylperoxy radical, CH3C(O)CH2OO, may play an important role in the oxidation chemistry of the troposphere. Using a temperature-controlled slow-flow tube cell and laser flash photolysis of Cl2 to produce HO2 and CH3C(O)CH2OO from methanol and acetone, respectively, we studied the chemical kinetics involved over the temperature range of 215 to 298 K at 100 Torr. Rates of chemical reactions were determined by monitoring the HO2 concentration as a function of time by near-IR diode laser wavelength modulation spectroscopy. (See Fig.1.) The primary reactions are rapid (<100 μsec) reactions to form the adducts HO2-CH3OH and HO2-CH3C(O)CH3 followed by HO2 reactions with itself, the adducts (chaperone mechanisms), and acetonylperoxy radical. The equilibrium constants for adduct formation were determined in previous work.1,2 In this work, rate coefficients were determined for the acetone chaperone mechanism over the entire temperature range. (E.g., see Fig. 2.) The rate coefficients and energies obtained are very similar to those found for the methanol case.1 Rate coefficients for the CH3C(O)CH2OO/HO2 reaction were also determined over a smaller temperature range, extending the measured value beyond room temperature, and yielding an activation energy. 1. Christensen et al. J. Phys. Chem. A 2006, 110, 6948-6959. 2. Grieman et al. J. Phys. Chem. A 2011, 115, 10527-10538. Fig.1. HO2 decay for HO2/Acetone chemistry at T = 298 K. Fig.2. Determining rate coefficient (k") for HO2/acetone chaperone effect at T = 222.5 K.

  17. Heme oxygenase-1 (HO-1) inhibits postmyocardial infarct remodeling and restores ventricular function.

    PubMed

    Liu, Xiaoli; Pachori, Alok S; Ward, Christopher A; Davis, J Paul; Gnecchi, Massimiliano; Kong, Deling; Zhang, Lunan; Murduck, Jared; Yet, Shaw-Fang; Perrella, Mark A; Pratt, Richard E; Dzau, Victor J; Melo, Luis G

    2006-02-01

    We reported previously that predelivery of the anti-oxidant gene heme oxygenase-1 (HO-1) to the heart by adeno associated virus (AAV) markedly reduces injury after acute myocardial infarction (MI). However, the effect of HO-1 gene delivery on postinfarction recovery has not been investigated. In the current study, we assessed the effect of HO-1 gene delivery on post-MI left ventricle (LV) remodeling and function using echocardiographic imaging and histomorphometric approaches. Two groups of Sprague-Dawley rats were injected with 4 x 10(11) particles of AAV-LacZ (control) or AAV-hHO-1 in the LV wall. Eight wk after gene transfer, the animals were subjected to 30 min of ischemia by ligation of left anterior descending artery (LAD) followed by reperfusion. Echocardiographic measurements were obtained in a blinded fashion prior and at 1.5 and 3 months after I/R. Ejection fraction (EF) was reduced by 13% and 40% in the HO-1 and LacZ groups, respectively at 1.5 months after MI. Three months after MI, EF recovered fully in the HO-1, but only partially in the LacZ-treated animals. Post-MI LV dimensions were markedly increased and the anterior wall was markedly thinned in the LacZ-treated animals compared with the HO-1-treated animals. Significant myocardial scarring and fibrosis were observed in the LacZ-group in association with elevated levels of interstitial collagen I and III and MMP-2 activity. Post-MI myofibroblast accumulation was reduced in the HO-1-treated animals, and retroviral overexpression of HO-1 reduced proliferation of isolated cardiac fibroblasts. Our data indicate that rAAV-HO-1 gene transfer markedly reduces fibrosis and ventricular remodeling and restores LV function and chamber dimensions after myocardial infarction. PMID:16449792

  18. Ultra-separation of nickel from copper metal for the measurement of 63Ni by AMS

    NASA Astrophysics Data System (ADS)

    Marchetti, A. A.; Hainsworth, L. J.; McAninch, J. E.; Leivers, M. R.; Jones, P. R.; Proctor, I. D.; Straume, T.

    1997-03-01

    Measurements of 63Ni (t{1}/{2} = 100 yr) produced by the reaction 63Cu(n,p)63Ni could be used in the assessment of fast-neutron fluence from the Hiroshima atomic bomb. Such measurements would add new information to help resolve the current discrepancy between measured thermal neutron activation values and those calculated with the DS86 dosimetry system. It has been estimated that the 63Ni production at 5 m from the hypocenter was (1.4 ± 0.1) × 107 atoms/g Cu. Because of its sensitivity, accelerator mass spectrometry (AMS) is ideal for measurements at this low level. However, 63Ni has to be separated from large amounts of stable atomic isobar 63Cu (69% of pure Cu). In this study, a procedure is presented for the electrochemical separation of ultra-low amounts of Ni from Cu. The method was developed using samples of electrical Cu wire that were irradiated with fission neutrons from a 252Cf source. The wire samples were electrochemically dissolved in a solution containing 1 mg of Ni carrier. The Cu was selectively deposited on a cathode at controlled potential. Measurements of total Ni after electroseparation indicate ˜ 100% carrier recovery. To prevent Cu contamination, AMS targets were prepared by nickel carbonyl generation. The AMS results show a successful quantitative separation of ˜ 107 atoms of 63Ni from 2-20 g samples of Cu.

  19. Electrochromic properties of NiOx:H films deposited by DC magnetron sputtering for ITO/NiOx:H/ZrO2/WO3/ITO device

    NASA Astrophysics Data System (ADS)

    Dong, Dongmei; Wang, Wenwen; Dong, Guobo; Zhou, Yuliang; Wu, Zhonghou; Wang, Mei; Liu, Famin; Diao, Xungang

    2015-12-01

    NiOx:H thin films were deposited on ITO-coated glass by DC reactive magnetron sputtering at room temperature. The effects of the hydrogen content on the structure, morphologies, electrochemical properties, the stoichiometry and chemical states of NiOx:H thin films were systematically studied. In X-ray diffraction and atomic force microscopy analysis, the crystallinity of the films tends to be weakened when the flow amount ratio of Ar:O2:H2 equals 19:1:3 and as confirmed in electrochemical analysis, such relatively weak crystallinity is the main contributing factor to ion transportation. X-ray photoelectron spectroscopy reveals that the increase of the hydrogen contents results in a relatively lower binding energy exhibited in the Ni 2p spectra. The proportion of Ni2O3 in NiOx:H films increases from 22% at bleached state to 33% at colored state. A monolithic all-thin-film inorganic electrochromic device was fabricated with complementary configuration as ITO/NiOx:H/ZrO2/WO3/ITO. The electrochromic device with optimized NiOx:H thin films acting both as ion storage layer and proton-providing source displays high modulation efficiency of 68% at a fixed wavelength 550 nm.

  20. Ni2P nanosheets/Ni foam composite electrode for long-lived and pH-tolerable electrochemical hydrogen generation.

    PubMed

    Shi, Yanmei; Xu, You; Zhuo, Sifei; Zhang, Jingfang; Zhang, Bin

    2015-02-01

    The continuous consumption of fossil fuels and accompanying environmental problems are driving the exploration of low-cost and effective electrocatalysts to produce clean hydrogen. A Ni2P nanosheets/Ni foam composite, as a non-noble metal electrocatalyst, has been prepared through a facile chemical conversion pathway using surface oxidized Ni foam as precursor and low concentration of trioctylphosphine (TOP) as a phosphorus source. Further investigation shows the oxidized layer of Ni foam can orient the formation of Ni2P nanosheets and facilitate the reaction with TOP. The Ni2P/Ni, acting as a robust 3D self-supported superaerophobic hydrogen-evolving cathode, shows superior catalytic performance, stability, and durability in aqueous media over a wide pH value of 0-14, making it a versatile catalyst system for hydrogen generation. Such highly active, stable, abundant, and low-cost materials hold enormously promising potential applications in the fields of catalysis, energy conversion, and storage. PMID:25564726

  1. Ni-based heterogeneous catalyst from a designed molecular precursor for the efficient electrochemical water oxidation.

    PubMed

    Kuznetsov, Denis A; Konev, Dmitry V; Komarova, Natal'ya S; Ionov, Andrey M; Mozhchil, Rais N; Fedyanin, Ivan V

    2016-07-28

    Bimetallic Ni-Mo alkoxide was synthesized and exploited as the single-source precursor for the solution-processed deposition of the mixed-oxide layers on different conducting surfaces. Upon potential cycling in 1 M NaOH, these composites convert, in situ, into highly porous NiOx/NiOOH catalysts characterized by the high electrocatalytic activity for water oxidation under both basic (pH 13.6) and near neutral (pH 9.2) conditions. PMID:27354324

  2. Dynamics of the Ho+3 magnetism in the multiferroic compound HoMnO3 investigated via time domain terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Armitage, N. P.; Laurita, N. J.; Hu, Rongwei; Cheong, S.-W.

    The multiferroic insulator HoMnO3 possesses a diverse array of magnetism due to both magnetically active Mn+3 and Ho+3 moments, the latter of which sit at two distinct sites within its non-inversion symmetric hexagonal crystal structure. While previous studies have focused on the ordering of the Mn+3 moments, little is known about the magnetic structure below 5K where it is believed that there is at least partial ordering of the Ho+3 ions. In principle, magnetic exchange interactions exist between both distinct Ho+3 and Mn+3 ions, resulting in an complex phase diagram with as many as five distinct phases found below T = 5 K and H = 3 T. While previous infrared studies have focused on the Ho+3 crystal field levels, the spin excitations in the low frequency end of the far infrared remain unknown. We report the finding of new infrared absorptions via time domain terahertz spectroscopy which we attribute to the Ho+3 moments. The corresponding field dependence is studied.

  3. 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.

  4. UV-VUV synchrotron radiation spectroscopy of NiWO4

    NASA Astrophysics Data System (ADS)

    Kuzmin, A.; Pankratov, V.; Kalinko, A.; Kotlov, A.; Shirmane, L.; Popov, A. I.

    2016-07-01

    Photoluminescence and excitation spectra of microcrystalline and nanocrystalline nickel tungstate (NiWO4) were measured using UV-VUV synchrotron radiation source. The origin of the bands is interpreted using comparative analysis with isostructural ZnWO4 tungstate and based on the results of recent first-principles band structure calculations. The influence of the local atomic structure relaxation and of Ni2+ intra-ion d-d transitions on the photoluminescence band intensity are discussed.

  5. 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

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

    PubMed

    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

  7. Final Viking NiCd battery conditioning

    SciTech Connect

    Britting, A.

    1983-08-01

    The Viking Lander Monitor Mission (VLMM) is well beyond its planned 90-day landed Mars mission. It has been an established NASA goal to maintain an American presence on Mars for as long as possible. With healthy subsystems, the mission could conceivably last until December 5, 1994. At that time the radioisotope thermoelectric generator (RTG) power source output power would be marginal for support of the system electrical loads and for battery maintenance. The antenna pointing coefficients will also expire at that time, resulting in telecommunication system shutdown. Recently three of the four, 8 ampere-hour (AH) nickel-cadmium (NiCd) batteries onboard Viking Lander 1 (VL-1) have indicated signs of significant loss of energy storage capacity. An intensive program of deep-discharge battery reconditioning was begun in January 1982 in an attempt to return the batteries to levels of capacity approaching early mission values.

  8. Upconverted photoluminescence in Ho3+ and Yb3+ codoped Gd2O3 nanocrystals with and without Li+ ions.

    PubMed

    Jia, Yutao; Song, Yinglin; Bai, Yunfeng; Wang, Yuxiao

    2011-01-01

    The upconversion photoluminescence of Ho(3+) ion sensitized by Yb(3+) ion in Ho(3+)/Yb(3+) codoped Gd(2)O(3) nanocrystals with and without Li(+) is investigated in this paper. Strong fluorescence in the green (534-570 nm) and red (635-674 nm) regions of the spectrum has been observed, arising from the (5)F(4)/(5)S(2) → (5)I(8) and (5)F(5) → (5)I(8) transitions of Ho(3+) ion, respectively. Yb(3+) ion is considered to be a better sensitizer for catching enough pumping energy and transferring considerable energy to Ho(3+) in the Ho(3+)/Yb(3+) system. The upconversion intensity emitted by Ho(3+) is greatly enhanced when Li(+) is added to the Ho(3+)/Yb(3+) codoped Gd(2)O(3) nanocrystals. PMID:20839377

  9. Thermal modeling of NiH2 batteries

    NASA Technical Reports Server (NTRS)

    Ponthus, Agnes-Marie; Alexandre, Alain

    1994-01-01

    The following are discussed: NiH2 battery mission and environment; NiH2 cell heat dissipation; Nodal software; model development general philosophy; NiH2 battery model development; and NiH2 experimental developments.

  10. Ni5, Ni8, and Ni10 clusters with 2,6-diacetylpyridine-dioxime as a ligand.

    PubMed

    Escuer, Albert; Esteban, Jordi; Roubeau, Olivier

    2011-09-19

    In the present work, novel coordination possibilities for the system dapdoH(2)/Ni(II) (dapdoH(2) = 2,6-diacetylpyridine-dioxime) have been explored. Depending on the starting reagents and solution conditions, several clusters with nuclearities ranging from Ni(5) to Ni(10) were achieved and structurally characterized, namely, [Ni(5)(R-COO)(2)(dapdo)(2)(dapdoH)(2)(N(CN)(2))(2)(MeOH)(2)] in which R-COO(-) = benzoate (1) or 3-chlorobenzoate (2), [Ni(8)(dapdo)(4)(NO(3))(4)(OH)(4)(MeOH)(4)] (3), and [Ni(10)(dapdo)(8)(N(CN)(2))(2)(MeO)(MeOH)](NO(3)) (4). For the first time, pentadentate coordination for the dapdo(2-) ligand has been established. All compounds show a combination of square-planar and octahedrally coordinated nickel atoms. According to the Ni(2)(sp)Ni(3)(Oh) (1 and 2), Ni(4)(sp)Ni(4)(Oh) (3), and Ni(4)(sp)Ni(6)(Oh) (4) environments, these systems magnetically behave as trimer, tetramer, and hexanuclear clusters, respectively. dc magnetic measurements in the 2-300 K range of temperature reveal antiferromagnetic coupling for all compounds, and the correlation of the superexchange interaction with the torsion angles involving the oximato bridges is experimentally confirmed. PMID:21853990

  11. 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.

  12. 60W Ho:YLF oscillator-amplifier system

    NASA Astrophysics Data System (ADS)

    Koen, Wayne; Jacobs, Cobus; Wu, Lorinda; Strauss, Hencharl J.

    2015-02-01

    We developed a compact Ho:YLF oscillator-amplifier system end-pumped by two 54 W unpolarised Tm:fibre lasers, and produced 60.2 W of output power at 2064 nm. The oscillator consisted of a flat input coupler mirror, a 50 mm long 0.5 % doped Ho:YLF crystal rod, a 45 degree folding mirror, an AOM, and a concave output coupler mirror. The oscillator operated vertically polarised on the holmium crystal's σ-polarisation, ensuring good beam quality from the weak thermal lens. The concave output coupler had a radius of 300 mm and a reflectivity of 82 % at 2064 nm. The oscillator gave a maximum output of 24 W with an M2 of 1.06. The single-pass amplifier consisted of two 40 mm long, 0.5 % doped, Ho:YLF crystal rods and four folding mirrors. While the seed laser was pumped by a single fibre laser, the amplifier utilized the transmitted pump light from the seed laser in addition to the second fibre laser. With the first crystal amplifying on the σ-polarisation and the second crystal on the π-polarisation, the amplifier delivered 60.2 W with an M2 of 1.09, representing a gain of 2.5 while achieving an optical-to-optical efficiency of 55.5 %. When Q-switched with the AOM, the system delivered pulse lengths of between 43 and 113 ns at repetition rates from 15 to 40 kHz.

  13. Lifshitz holographic superconductor in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Luo, Cheng-Jian; Kuang, Xiao-Mei; Shu, Fu-Wen

    2016-08-01

    We study the holographic phase transition of superconductor dual to a Lifshitz black brane probed by an anisotropic scalar field in the probe limit in Hořava-Lifshitz gravity. With the use of numerical and analytical method, we investigate how the critical temperature of the condensation is affected by the Lifshitz exponent z, α-correction term in the action as well as the dimensions of the gravity. We also numerically explore the condensation of the dual operator and optical conductivity of the holographic system. Various interesting properties of the holographic condensation affected by the parameters of model are discussed.

  14. 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.

  15. Lasing characteristics of Ho:YAG single crystal fiber.

    PubMed

    Li, Yuan; Miller, Keith; Johnson, Eric G; Nie, Craig D; Bera, Subhabrata; Harrington, James A; Shori, Ramesh

    2016-05-01

    Lasing was demonstrated for the first time at 2.09 μm in 0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) fabricated using the Laser Heated Pedestal Growth (LHPG) method. Output power of 23.5 W with 67.5% optical-to-optical slope efficiency is, to the best of our knowledge, the highest output power achieved at 2 µm from a SCF fabricated using LHPG. With continued improvement in the quality of the SCF and better thermal management, output power of few 100s W and higher, especially in the 2 µm spectral region, is realizable in the very near future. PMID:27137589

  16. Detailed course of the O + HO2 reaction

    NASA Technical Reports Server (NTRS)

    Sridharan, U. C.; Klein, F. S.; Kaufman, F.

    1985-01-01

    The elementary radical-radical reactions that are of such importance in laser, astrophysical, atmospheric, and combustion processes are increasingly open to direct rate measurement. Attention is presently given to the O + HO2 reaction, which has only one exothermic product channel: OH + O2. Isotopic product analysis was conducted spectroscopically using laser-induced fluorescence of OH. It is found that the simple atom-radical reaction takes place by way of the rapid formation and breakup of an unexpected radical intermediate, thereby raising questions as to the formation, thermochemistry, and decomposition of poorly known products in many other radical-radical reaction systems.

  17. On the similarity of the bonding in NiS and NiO

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1985-01-01

    The bonding in NiS is found to be quite similar to that in NiO, having an ionic contribution arising from the donation of the Ni 4s electron to the S atom and a covalent component arising from bonds between the Ni 3d and the S 3p. The one-electron d bonds are found to be of equal strength for NiO and NiS, but the two-electron d bonds are weaker for NiS.

  18. Recycling Ni from Contaminated and Mineralized Soils.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rare plant species accumulate potentially valuable concentrations of some metals. Alyssum murale readily accumulates over 2% Ni in aboveground dry matter when grown on Ni-mineralized serpentine soils in Oregon, allowing production of “hay” biomass with at least 400 kg Ni ha-1 with low levels of fer...

  19. Oxygen potentials in Ni + NiO and Ni + Cr[sub 2]O[sub 3] + NiCr[sub 2]O[sub 4] systems

    SciTech Connect

    Kale, G.M.; Fray, D.J. . Dept. of Mining and Mineral Engineering)

    1994-06-01

    The chemical potential of O for the coexistence of Ni + NiO and Ni + Cr[sub 2]O[sub 3] + NiCr[sub 2]O[sub 4] equilibria has been measured employing solid-state galvanic cells, (+) Pt, Cu + Cu[sub 2]O [vert bar][vert bar] (Y[sub 2]O[sub 3])ZrO[sub 2] [vert bar][vert bar] Ni + NiO, Pt (-) and (+) Pt, Ni + NiO [vert bar][vert bar] (Y[sub 2]O[sub 3])ZrO[sub 2] [vert bar][vert bar] Ni + Cr[sub 2]O[sub 3] + NiCr[sub 2]O[sub 4], Pt (-) in the temperature range of 800 to 1,300 K and 1,100 to 1,460 K, respectively. The electromotive force (emf) of both he cells was reversible, reproducible on thermal cycling, and varied linearly with temperature. for the coexistence of the two-phase mixture of Ni + NiO, [Delta][mu][sub O[sub 2

  20. Low temperature specific heat of frustrated antiferromagnet HoInCu4

    NASA Astrophysics Data System (ADS)

    Weickert, Franziska; Fritsch, Veronika; Bambaugh, Ryan; Sarrao, John; Thompson, Joe D.; Movshovich, Roman

    2014-03-01

    We present low temperature specific heat measurements of single crystal HoInCu4, down to 35 mK and in magnetic field up to 12 Tesla. Ho atoms are arranged in an FCC lattice of the edge-sharing tetrahedra, and undergo an antiferromagnetic ordering at TN = 0.76 K, with the frustration parameter f = -ΘCW /TN of 14.3. Magnetic AF order is suppressed in field H0 ~ 4 T. The low temperature Schottky anomaly due to Ho evolves smoothly as a function of field through H0 and TN. The peak value of the anomaly remains roughly constant from 0 T to 12 T. The temperature of the anomaly's peak remains constant at TSch ~ 170 mK for HHo spins in zero field as well as an increasing moment on Ho once the AF order is suppressed. The measured entropy of HoInCu4 at 12 T and 2K is 17.32 J/mol-K ~ Rln8 expected for an I =7/2 nuclear spin of Ho. Work at LANL was performed under the auspices of the US DOE, OBES, MSE division.

  1. Photocatalytic activity of Ho-doped anatase titanium dioxide coated magnetite.

    PubMed

    Shi, Zhongliang; Xiang, Yongfang; Zhang, Xiaoyan; Yao, Shuhua

    2011-01-01

    A composite photocatalyst (Ho/TiO(2)/Fe(3)O(4)) with Ho-doped anatase titanium dioxide (Ho/TiO(2)) shell and a magnetite core was prepared by coating photoactive Ho/TiO(2) onto a magnetic Fe(3)O(4) core through the hydrolysis of tetrabutyltitanate (Ti(OBu)(4), TBT) in water/oil (w/o) microemulsion with precursors of Ho(NO(3))(3) and TBT in the presence of Fe(3)O(4) nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-Vis diffusive reflectance spectroscopy (UV-Vis DRS). The effect of Ho ion content on the photocatalytic activity was studied. The photodegradation behavior of the prepared photocatalyst under UV and visible light was investigated in aqueous solution using methyl orange (MO) as target pollutant. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photo-oxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Ho/TiO(2) was tightly bound to Fe(3)O(4) and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants. PMID:21208216

  2. HO-1 Upregulation Attenuates Adipocyte Dysfunction, Obesity, and Isoprostane Levels in Mice Fed High Fructose Diets

    PubMed Central

    Harsh, Mohit; Sodhi, Komal; Shapiro, Joseph I.; Abraham, Nader G.

    2014-01-01

    Background. Fructose metabolism is an unregulated metabolic pathway and excessive fructose consumption is known to activate ROS. HO-1 is a potent antioxidant gene that plays a key role in decreasing ROS and isoprostanes. We examined whether the fructose-mediated increase in adipocyte dysfunction involves an increase in isoprostanes and that pharmacological induction of HO-1 would decrease both isoprostane levels and adipogenesis. Methods and Results. We examined the effect of fructose, on adipogenesis in human MSCs in the presence and absence of CoPP, an inducer of HO-1. Fructose increased adipogenesis and the number of large lipid droplets while decreasing the number of small lipid droplets (P < 0.05). Levels of heme and isoprostane in fructose treated MSC-derived adipocytes were increased. CoPP reversed these effects and markedly increased HO-1 and the Wnt signaling pathway. The high fructose diet increased heme levels in adipose tissue and increased circulating isoprostane levels (P < 0.05 versus control). Fructose diets decreased HO-1 and adiponectin levels in adipose tissue. Induction of HO-1 by CoPP decreased isoprostane synthesis (P < 0.05 versus fructose). Conclusion. Fructose treatment resulted in increased isoprostane production and adipocyte dysfunction, which was reversed by the increased expression of HO-1. PMID:25295182

  3. Reaction of amorphous Ni-W and Ni-N-W films with substrate silicon

    NASA Technical Reports Server (NTRS)

    Zhu, M. F.; Suni, I.; Nicolet, M.-A.; Sands, T.

    1984-01-01

    Wiley et al. (1982) have studied sputtered amorphous films of Nb-Ni, Mo-Ni, Si-W, and Si-Mo. Kung et al. (1984) have found that amorphous Ni-Mo films as diffusion barriers between multilayer metallizations on silicon demonstrate good electrical and thermal stability. In the present investigation, the Ni-W system was selected because it is similar to the Ni-Mo system. However, W has a higher silicide formation temperature than Mo. Attention is given to aspects of sample preparation, sample characterization, the interaction between amorphous Ni-W films and Si, the crystallization of amorphous Ni(36)W(64) films on SiO2, amorphous Ni-N-W films, silicide formation and phase separation, and the crystallization of amorphous Ni(36)W(64) and Ni(30)N(21)W(49) layers.

  4. El Niño, past and present

    NASA Astrophysics Data System (ADS)

    Enfield, David B.

    1989-02-01

    El Niño events—anomalous warmings of the tropical Pacific with associated climatic and economic impacts around the globe—have occurred at several-year intervals since before written records began with the logs of Francisco Pizarro in 1525. In this review, the history of El Niño research is traced from its beginnings through the key innovations of Bjerknes and Wyrtki to the unusual 1982-1983 event. Recent research is then reviewed, with detailed discussions of two important processes: instability growth and vacillation between climate states. Throughout the paper there are adjunct discussions of extraregional teleconnections, ecological impacts, and research on El Niño in the ancient record. The final section discusses the present paradigm for vacillations between El Niño and non-El Niño states and speculates on the possibly chaotic nature of El Niño. El Niño and its atmospheric counterpart, the Southern Oscillation, appear to occur as an internal cycle of positive and negative feedbacks within the coupled ocean-atmosphere climate system of the tropical Pacific, although hypotheses based on external forcing also exist. All events are preceded by westerly wind anomalies on the equator near the date line. Baroclinic equatorial Kelvin waves are generated, propagating eastward toward South America where they depress the thermocline and raise sea level, while the deep, upper ocean reservoir of warm water in the western Pacific is depleted. Sea surface temperature (SST) anomalies in the cool eastern Pacific occur primarily because the normal source of cold water is depressed below the reach of mixing and upwelling processes. In the central equatorial Pacific, eastward advection by anomalous zonal flows is the principal mechanism. Nonlinear heat transfer to the lower atmosphere creates a positive ocean-atmosphere feedback resulting in the unstable growth of anomalies along the equator. Much of the present research aims at determining how the ocean

  5. Downregulation of Heme Oxygenase 1 (HO-1) Activity in Hematopoietic Cells Enhances Their Engraftment After Transplantation.

    PubMed

    Adamiak, Mateusz; Moore, Joseph B; Zhao, John; Abdelbaset-Ismail, Ahmed; Grubczak, Kamil; Rzeszotek, Sylwia; Wysoczynski, Marcin; Ratajczak, Mariusz Z

    2016-01-01

    Heme oxygenase 1 (HO-1) is an inducible stress-response enzyme that not only catalyzes the degradation of heme (e.g., released from erythrocytes) but also has an important function in various physiological and pathophysiological states associated with cellular stress, such as ischemic/reperfusion injury. HO-1 has a well-documented anti-inflammatory potential, and HO-1 has been reported to have a negative effect on adhesion and migration of neutrophils in acute inflammation in a model of peritonitis. This finding is supported by our recent observation that hematopoietic stem progenitor cells (HSPCs) from HO-1 KO mice are easy mobilizers, since they respond better to peripheral blood chemotactic gradients than wild-type littermates. Based on these findings, we hypothesized that transient inhibition of HO-1 by nontoxic small-molecule inhibitors would enhance migration of HSPCs in response to bone marrow chemoattractants and thereby facilitate their homing. To directly address this issue, we generated several human hematopoietic cell lines in which HO-1 was upregulated or downregulated. We also exposed murine and human BM-derived cells to small-molecule activators and inhibitors of HO-1. Our results indicate that HO-1 is an inhibitor of hematopoietic cell migration in response to crucial BM homing chemoattractants such as stromal-derived factor 1 (SDF-1) and sphingosine-1-phosphate (S1P). Most importantly, our in vitro and in vivo animal experiments demonstrate for the first time that transiently inhibiting HO-1 activity in HSPCs by small-molecule inhibitors improves HSPC engraftment. We propose that this simple and inexpensive strategy could be employed in the clinical setting to improve engraftment of HSPCs, particularly in those situations in which the number of HSPCs available for transplant is limited (e.g., when transplanting umbilical cord blood). PMID:27412411

  6. 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

  7. Kinetics of Ni2Si growth from pure Ni and Ni(V) films on (111) and (100) Si

    NASA Astrophysics Data System (ADS)

    Harith, M. A.; Zhang, J. P.; Campisano, S. U.; Klaar, H.-J.

    1987-01-01

    The kinetics of Ni2Si growth from pure Ni and from Ni0.93V0.07 films on (111) and (100) silicon has been studied by the combination of He+ backscattering, x-ray diffraction, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) techniques. The activation energies are 1.5 and 1.0 eV for pure Ni and Ni(V) films, respectively while the pre-exponential factors in Ni(V) are 4 5 orders of magnitude smaller than in the pure Ni case. The variations in the measured rates are related to the different grain size of the growing suicide layers. The vanadium is rejected from the silicide layer and piles up at the metalsilicide interface.

  8. Resistivity of the HoIn 3 and ErIn 3 single crystals

    NASA Astrophysics Data System (ADS)

    Kletowski, Z.; Sławiński, P.

    1990-11-01

    We report results of the resistivity measurements of HoIn 3 and ErIn 3 in temperature range 4.2-300 K. A comparison of these data with that for the nonmagnetic LuIn 3 indicates a big similarity of these three temperature dependences of the resistivity. An appearance of the spin disorder resistivity for the HoIn 3 and ErIn 3 is noticed. The resistivity results confirm the existence of an anomaly observed before for the HoIn 3 in the ordered phase.

  9. Thermomechanical properties of Cr:Tm:Ho:Y sub 3 Al sub 5 O sub 12

    SciTech Connect

    Marion, J.E.

    1990-05-15

    The thermomechanical properties of Cr:Ho:Tm:Y{sub 3}Al{sub 5}O{sub 12} have been measured and compared to similar measurements on Nd:Y{sub 3}Al{sub 5}O{sub 12}. We find that, in general, the properties are similar, with the single exception being thermal diffusivity. Nd:YAG has substantially higher thermal diffusivity than Cr:Tm:Ho:YAG. Consequently, the intrinsic thermal stress resistance figure of merit which governs a materials resistance to fracture in the presence of a steady thermal gradient is lower in Cr:Tm:Ho:YAG than in Nd:YAG. 6 refs., 1 tab.

  10. Single-longitudinal-mode Ho:LuAG laser at 2.1 μm

    NASA Astrophysics Data System (ADS)

    Liu, W.; Ju, Y. L.; Dai, T. Y.; Cui, Z.; Wu, J.; Yao, B. Q.; Duan, X. M.; Shen, Y. J.; Wang, Y. Z.

    2016-02-01

    In this letter we report a continuous wave Ho:LuAG laser running on single-longitudinal-mode operation. Two Fabry-Perot etalons were used to narrow the laser line-width. By regulating the angle of the etalons, single-longitudinal-mode lasing was achieved at a wavelength of 2100.65 nm. The maximum power and the slope efficiency of single-longitudinal-mode Ho:LuAG output are 264 mW and 14.5%, respectively. To our knowledge, this is the first time a Ho:LuAG laser with single-longitudinal-mode operation has been obtained.

  11. Measurement of atmospheric HO by a chemical method

    NASA Astrophysics Data System (ADS)

    Iyer, R. Subramonia; Rowland, F. Sherwood

    1986-12-01

    The parameters for a chemical technique can be outlined from the following set of desirable goals: (1) sufficient conversion of tracer species A to product B that B can be measured quantitatively in the presence of A and a great excess of air; (2) specificity of reaction such that A is converted to B only by reaction with HO; and (3) sufficient sensitivity for detection that the ambient concentration of HO is not seriously perturbed by the presence of A and B. This proposed study involves finding a chemical reaction specific enough for OH, and a measurement of the product formed. What one wants is a rate constant of about 10 to the -10th power cu cm/s, so that 0.1 percent of the OH will be converted in 100 s. Laboratory studies are needed to find a reaction which will fill this bill, yielding a product in quantity sufficient for precise measurement. This is an extremely fast constant and the search may be difficult. Again there is a question of perturbing the local environment, while still providing a sensitive measurement. Also the temperature and pressure dependence of the reaction rate is a complicated function for many of these species (that is, one must use a RRKM or Troe-based picture), and must be taken into account.

  12. Minimally invasive scoliosis treatment with a Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Rumpf, Christian G.; Lang, Robert D.; Goetz, Marcus H.

    2000-11-01

    Today most surgical treatment of spinal deformations is concentrated on invasive mechanical techniques with long operation times and major effects on the patient's mobility. The proposed minimally invasive technique using laser light for tissue ablation offers a possibility of gentle scoliosis treatment. It is thought that an early removal of the epiphysial growth zone on the convex side over several vertebrae results in a straightening of the spine. In a first evaluation, four different laser systems including argon ion, Nd:YAG (Q-switched), Nd:YAG (cw), and Ho:YAG laser were compared with respect to thermal damage to adjacent tissue, ablation rates, efficiency and laser handling. For in-vivo investigation, fresh lamb spine was used. Comparison showed that the Ho:YAG laser is the most appropriate laser for the given goal, providing efficient photoablation with moderate thermal effects on the adjacent tissue. In a second step the proposed minimally invasive operation technique was performed in in-vivo experiments on young foxhounds using 3D- thoracoscopic operation techniques. During these operations temperature mapping was done using fiber-optic fluorescent probes. After 12 months of normal growth the animals were sacrificed and x-ray as well as MRI was performed on the spine. First results show a positive effect of scoliotic growth in two cases. Being able to produce a scoliosis by hemiepiphysiodesis on the vertebra, It is thought that this technique is successful for a straightening of the spine on patients with scoliosis.

  13. 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.

  14. Itinerant and localized magnetization dynamics in antiferromagnetic Ho

    DOE PAGESBeta

    Rettig, L.; Dornes, C.; Thielemann-Kuhn, N.; Pontius, N.; Zabel, H.; Schlagel, D. L.; Lograsso, T. A.; Chollet, M.; Robert, A.; Sikorski, M.; et al

    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

  15. Measurement of atmospheric HO by a chemical method

    NASA Technical Reports Server (NTRS)

    Iyer, R. Subramonia; Rowland, F. Sherwood

    1986-01-01

    The parameters for a chemical technique can be outlined from the following set of desirable goals: (1) sufficient conversion of tracer species A to product B that B can be measured quantitatively in the presence of A and a great excess of air; (2) specificity of reaction such that A is converted to B only by reaction with HO; and (3) sufficient sensitivity for detection that the ambient concentration of HO is not seriously perturbed by the presence of A and B. This proposed study involves finding a chemical reaction specific enough for OH, and a measurement of the product formed. What one wants is a rate constant of about 10 to the -10th power cu cm/s, so that 0.1 percent of the OH will be converted in 100 s. Laboratory studies are needed to find a reaction which will fill this bill, yielding a product in quantity sufficient for precise measurement. This is an extremely fast constant and the search may be difficult. Again there is a question of perturbing the local environment, while still providing a sensitive measurement. Also the temperature and pressure dependence of the reaction rate is a complicated function for many of these species (that is, one must use a RRKM or Troe-based picture), and must be taken into account.

  16. Kinetics of Ni Sorption in Soils: Roles of Soil Organic Matter and Ni Precipitation

    SciTech Connect

    Shi, Zhenqing; Peltier, Edward; Sparks, Donald L.

    2012-12-10

    The kinetics of Ni sorption to two Delaware agricultural soils were studied to quantitatively assess the relative importance of Ni adsorption on soil organic matter (SOM) and the formation of Ni layered double hydroxide (Ni-LDH) precipitates using both experimental studies and kinetic modeling. Batch sorption kinetic experiments were conducted with both soils at pH 6.0, 7.0, and 7.5 from 24 h up to 1 month. Time-resolved Ni speciation in soils was determined by X-ray absorption spectroscopy (XAS) during the kinetic experiments. A kinetics model was developed to describe Ni kinetic reactions under various reaction conditions and time scales, which integrated Ni adsorption on SOM with Ni-LDH precipitation in soils. The soil Ni speciation (adsorbed phases and Ni-LDH) calculated using the kinetics model was consistent with that obtained through XAS analysis during the sorption processes. Under our experimental conditions, both modeling and XAS results demonstrated that Ni adsorption on SOM was dominant in the short term and the formation of Ni-LDH precipitates accounted for the long-term Ni sequestration in soils, and, more interestingly, that the adsorbed Ni may slowly transfer to Ni-LDH phases with longer reaction times.

  17. Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH

    PubMed Central

    Hussein, Mohd Zobir; Mohamad Jaafar, Adila; Hj. Yahaya, Asmah; Masarudin, Mas Jaffri; Zainal, Zulkarnain

    2014-01-01

    Multi-walled carbon nanotubes (MWCNTs) were prepared via chemical vapor deposition (CVD) using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs). Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs. PMID:25380526

  18. Formation and yield of multi-walled carbon nanotubes synthesized via chemical vapour deposition routes using different metal-based catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH.

    PubMed

    Hussein, Mohd Zobir; Jaafar, Adila Mohamad; Yahaya, Asmah Hj; Masarudin, Mas Jaffri; Zainal, Zulkarnain

    2014-01-01

    Multi-walled carbon nanotubes (MWCNTs) were prepared via chemical vapor deposition (CVD) using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs). Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs. PMID:25380526

  19. Hydrogen production using thermocatalytic decomposition of methane on Ni30/activated carbon and Ni30/carbon black.

    PubMed

    Srilatha, K; Viditha, V; Srinivasulu, D; Ramakrishna, S U B; Himabindu, V

    2016-05-01

    Hydrogen is an energy carrier of the future need. It could be produced from different sources and used for power generation or as a transport fuel which mainly in association with fuel cells. The primary challenge for hydrogen production is reducing the cost of production technologies to make the resulting hydrogen cost competitive with conventional fuels. Thermocatalytic decomposition (TCD) of methane is one of the most advantageous processes, which will meet the future demand, hence an attractive route for COx free environment. The present study deals with the production of hydrogen with 30 wt% of Ni impregnated in commercially available activated carbon and carbon black catalysts (samples coded as Ni30/AC and Ni30/CB, respectively). These combined catalysts were not attempted by previous studies. Pure form of hydrogen is produced at 850 °C and volume hourly space velocity (VHSV) of 1.62 L/h g on the activity of both the catalysts. The analysis (X-ray diffraction (XRD)) of the catalysts reveals moderately crystalline peaks of Ni, which might be responsible for the increase in catalytic life along with formation of carbon fibers. The activity of carbon black is sustainable for a longer time compared to that of activated carbon which has been confirmed by life time studies (850 °C and 54 sccm of methane). PMID:26233751

  20. Laser Resonance Ionization Spectroscopy of the Lanthanides Tb, Dy and Ho as Homologues to Actinides and Super Heavy Elements

    SciTech Connect

    Gottwald, T.; Lassen, J.; Liu, Yuan; Mattolat, C.; Raeder, S.; Wendt, K.

    2009-03-01

    At Oak Ridge National Laboratory (ORNL) spectroscopic investigations of the rare earth elements Tb, Dy and Ho were carried out using laser resonance ionization mass spectroscopy (RIMS). Detailed spectroscopic studies are necessary to develop highly efficient and selective excitation and ionization schemes. Those schemes, carefully worked out under off-line conditions are mandatory for employment at laser ion sources at on-line facilities for studies of exotic radioactive nuclei e.g. 146Tb, as well as for laser-based ultra trace isotope analysis. Additionally, this work serves as preparatory step for related investigations on actinide elements and in preparation of the heaviest elements, where spectroscopic data so far are scarce or not existing at all.

  1. Seasonal change in the atmospheric concentration of particulate polycyclic aromatic hydrocarbons in Ho Chi Minh City, Vietnam.

    PubMed

    Kishida, Masao; Mio, Chihiro; Fujimori, Keiichi; Imamura, Kiyoshi; Takenaka, Norimichi; Maeda, Yasuaki; Lan, Tran Thi Ngoc; Shibutani, Yasuhiko; Bandow, Hiroshi

    2009-11-01

    We analyzed atmospheric particulate polycyclic aromatic hydrocarbons (PAHs) in Ho Chi Minh City, Vietnam, for 19 months. The average concentrations of total PAHs at dry and rainy seasons were 4.28 +/- 2.83 and 15.71 +/- 8.21 ng m(-3), respectively. The use of motorcycles without catalytic converters, estimated to be main emission sources of PAHs, would be higher during the dry season. PAH concentrations show a negative correlation with sunshine duration (r = -0.51). Furthermore, the ratio of average PAH concentration in the dry season to that in the rainy season shows a positive correlation with photolytic half-life (r = 0.94). Thus, seasonal changes in PAH concentrations are attributable to their photolytic degradation. PMID:19471847

  2. Strong magnetization damping induced by Ag nanostructures in Ag/NiFe/Ag trilayers

    NASA Astrophysics Data System (ADS)

    Ley Domínguez, D.; da Silva, G. L.; Rodríguez-Suárez, R. L.; Rezende, S. M.; Azevedo, A.

    2013-07-01

    Ferromagnetic resonance has been used to investigate the magnetization relaxation in trilayers of Ag(t)/NiFe(10 nm)/Ag(t), sputter deposited on Si(001) where the thickness of the Ag layer varied from 0 nm to 24 nm. In the first stages of formation, the Ag layers form islands that work as mold to imprint defects or inhomogeneities on the NiFe film surface. The magnetic inhomogeneities and defects imprinted on the surface of the NiFe film act as extrinsic sources of magnetization relaxation in addition to the intrinsic Gilbert damping mechanism. Weak inhomogeneities are associated to the two-magnon scattering source and the strong inhomogeneities are associated to the fluctuations of the local magnetization. By adding the three different sources of magnetization damping, we were able to explain the azimuthal dependence of the ferromagnetic resonance linewidth.

  3. 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%.

  4. Lung endothelial HO-1 targeting in vivo using lentiviral miRNA regulates apoptosis and autophagy during oxidant injury

    PubMed Central

    Zhang, Yi; Jiang, Ge; Sauler, Maor; Lee, Patty J.

    2013-01-01

    The lung endothelium is a major target for inflammatory and oxidative stress. Heme oxygenase-1 (HO-1) induction is a crucial defense mechanism during oxidant challenges, such as hyperoxia. The role of lung endothelial HO-1during hyperoxia in vivo is not well defined. We engineered lentiviral vectors with microRNA (miRNA) sequences controlled by vascular endothelium cadherin (VE-cad) to study the specific role of lung endothelial HO-1. Wild-type (WT) murine lung endothelial cells (MLECs) or WT mice were treated with lentivirus and exposed to hyperoxia (95% oxygen). We detected HO-1 knockdown (∼55%) specifically in the lung endothelium. MLECs and lungs showed approximately a 2-fold increase in apoptosis and ROS generation after HO-1 silencing. We also demonstrate for the first time that silencing endothelial HO-1 has the same effect on lung injury and survival as silencing HO-1 in multiple lung cell types and that HO-1 regulates caspase 3 activation and autophagy in endothelium during hyperoxia. These studies demonstrate the utility of endothelial-targeted gene silencing in vivo using lentiviral miRNA constructs to assess gene function and that endothelial HO-1 is an important determinant of survival during hyperoxia.—Zhang, Y., Jiang, G., Sauler, M., Lee, P. J. Lung endothelial HO-1 targeting in vivo using lentiviral miRNA regulates apoptosis and autophagy during oxidant injury. PMID:23771928

  5. Distinct photoproducts of hydroxylated polybromodiphenyl ethers from different photodegradation pathways: a case study of 2'-HO-BDE-68.

    PubMed

    Xie, Qing; Chen, Jingwen; Zhao, Hongxia; Wang, Xingbao; Xie, Hong-Bin

    2015-02-01

    Hydroxylated polyhalodiphenyl ethers (HO-PXDEs) are emerging aquatic pollutants. Previous studies have shown that HO-PXDEs can photogenerate dioxins and phenolic compounds. However, it is unclear which photochemical pathways are responsible for the various photoproducts. This study investigates the direct photolysis and photooxidation initiated by (1)O2 and ˙OH that can be formed by photosensitization, taking 2'-HO-2,3',4,5'-tetrabromodiphenyl ether (2'-HO-BDE-68) as a case study. The results show that 1,3,8-tribromodibenzo-p-dioxin can only be produced during direct photolysis. By mass spectrum analysis, four dihydroxylated polybromodiphenyl ethers, generated from both direct and indirect photodegradation were confirmed. Among them, di-HO-tribromodiphenyl ether (di-HO-TBDE) was the main product generated from direct photohydrolysis. Most probably, the di-HO-TBDE is 2',5'-HO-2,3',4-tribromodiphenyl ether, as was suggested by density functional theory calculations. Ether bond cleavage is a dominant pathway for the direct photolysis and photooxidation reactions leading to 2,4-dibromophenol as the dominant product. The yields of the products, which are irrespective of reaction time and can be employed to compare the ability of different HO-PXDEs to photogenerate a given product, were reported. This study indicates that for accurate ecological risk assessment of HO-PXDEs, their different photodegradation pathways that may lead to different photoproducts should be considered. PMID:25569145

  6. Magnetocaloric effect of RM2 (R = rare earth, M = Ni, Al) intermetallic compounds made by centrifugal atomization process for magnetic refrigerator

    NASA Astrophysics Data System (ADS)

    Matsumoto, K.; Asamato, K.; Nishimura, Y.; Zhu, Y.; Abe, S.; Numazawa, T.

    2012-12-01

    RM2 (R = rare earth, M = Al, Ni and Co) compounds have large entropy change and magnetic transition temperatures can be controlled by change of R and/or M so that are suitable to a magnetic refrigerator for hydrogen liquefaction under development. In order to improve refrigerator performance, spherical powdered HoAl2, DyAl2, and GdNi2 compounds with submillimeter diameter were synthesized by centrifugal atomization process. By measuring the magnetization and heat capacity, we obtained entropy change by magnetic fields and entropy as functions of temperature and magnetic field, which are essential for analysing the magnetic refrigeration cycle. All samples showed sharp magnetic transitions and had good potentials for use in magnetic refrigeration.

  7. Thermal Stability of Ni-Mn Electrodeposits

    SciTech Connect

    Talin, A. A.; Marquis, E. A.; Goods, S. H.; Kelly, J. J.; Miller, Michael K

    2006-01-01

    The effect of Mn additions on the structural stability of electrodeposited Ni is investigated by comparing the microstructure evolution of Ni and Ni-Mn specimens with similar crystallographic initial textures. As deposited, Ni-Mn electrodeposits have a smaller crystallite size and substantially higher yield strength than Ni deposits, in agreement with the Hall-Petch relationship. Moreover, dilute Ni-Mn electrodeposits exhibit a thermal stability that significantly exceeds that of pure Ni. Indeed, Ni-Mn retains its texture, fine-grain microstructure, and strength above 500 C (for 1 h anneal), and does not recrystallize up to 800 C. In contrast, pure Ni with larger average grain size and similar preferred orientation shows abnormal grain growth at 300 C and recrystallization at 600 C. This study suggests two distinct temperature regimes. Below 600 C, grain boundary segregation appears as a plausible mechanism for the thermal stability of Ni-Mn electrodeposits, whereas grain boundary pinning by precipitation contributes to the improved microstructural stability of Ni-Mn above 600 C.

  8. Phonon Dispersion in Amorphous Ni-Alloys

    NASA Astrophysics Data System (ADS)

    Vora, A. M.

    2007-06-01

    The well-known model potential is used to investigate the longitudinal and transverse phonon dispersion curves for six Ni-based binary amorphous alloys, viz. Ni31Dy69, Ni33Y67, Ni36Zr64, Ni50Zr50, Ni60 Nb40, and Ni81B19. The thermodynamic and elastic properties are also computed from the elastic limits of the phonon dispersion curves. The theoretical approach given by Hubbard-Beeby is used in the present study to compute the phonon dispersion curves. Five local field correction functions proposed by Hartree, Taylor, Ichimaru-Utsumi, Farid et al. and Sarkar et al. are employed to see the effect of exchange and correlation in the aforesaid properties.

  9. High-purity Ni electroless plating on screen-printed anodized Al substrates

    NASA Astrophysics Data System (ADS)

    Park, Sang-Geon; Lee, Youn-Seoung; Rha, Sa-Kyun

    2016-07-01

    By using an electroless plating process with a Ni source solution including dimethylamine borane (DMAB) at pH 6.5 and 65 ◦ C, we obtained a higher purity Ni film (< 1 at.% boron) without damage to the anodized Al substrate. With increasing plating time, the thickness of the film increased gradually, although the average deposition rate of the Ni films decreased steadily. We can infer that the abrupt decrease in sheet resistance (Rs) at the interface region is due to the change in the boron concentration caused by surface reactions, and the gradual decrease in Rs in the bulk region is due mainly to the effect of the saturation of boron's concentration on the thickness. From a boron-distribution viewpoint, this result indicates that the B concentration in the Ni film increases gradually with increasing plating time for plating times ≤ 60 s as a kind of initial stage (that is, interface region), and then saturates uniformly for plating times ≥ 300 s as a kind of bulk region. On the other hand, from an electronic structure viewpoint, this result implies that Ni gains 3d electrons with respect to elemental Ni. The increase in the number of electrons gained by the Ni 3d states may result in an enhancement of the electrical conductivity.

  10. 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.

  11. California Niño/Niña

    PubMed Central

    Yuan, Chaoxia; Yamagata, Toshio

    2014-01-01

    The present study shows the existence of intrinsic coastal air-sea coupled phenomenon in the coastal ocean off Baja California and California in boreal summer for the first time. It contributes significantly to the interannual sea surface temperature (SST) anomalies there. An initial decrease/increase in the equatorward alongshore surface winds weakens/strengthens the coastal upwelling and raises/lowers the coastal SSTs through oceanic mixed-layer processes. The resultant coastal warming/cooling, in turn, heats/cools the overlying atmosphere anomalously, decreases/increases the atmospheric pressure in the lower troposphere, generates an anomalous cross-shore pressure gradient, and thus reinforces or maintains the alongshore surface wind anomalies. The regional air-sea coupled phenomenon seems to be analogous to the well-known El Niño/Southern Oscillation (ENSO) in the tropical Pacific but with much smaller time and space scales, and may be referred to as California Niño/Niña in its intrinsic sense. PMID:24763062

  12. California Niño/Niña.

    PubMed

    Yuan, Chaoxia; Yamagata, Toshio

    2014-01-01

    The present study shows the existence of intrinsic coastal air-sea coupled phenomenon in the coastal ocean off Baja California and California in boreal summer for the first time. It contributes significantly to the interannual sea surface temperature (SST) anomalies there. An initial decrease/increase in the equatorward alongshore surface winds weakens/strengthens the coastal upwelling and raises/lowers the coastal SSTs through oceanic mixed-layer processes. The resultant coastal warming/cooling, in turn, heats/cools the overlying atmosphere anomalously, decreases/increases the atmospheric pressure in the lower troposphere, generates an anomalous cross-shore pressure gradient, and thus reinforces or maintains the alongshore surface wind anomalies. The regional air-sea coupled phenomenon seems to be analogous to the well-known El Niño/Southern Oscillation (ENSO) in the tropical Pacific but with much smaller time and space scales, and may be referred to as California Niño/Niña in its intrinsic sense. PMID:24763062

  13. COMBUSTION AREA SOURCES: DATA SOURCES

    EPA Science Inventory

    The report identifies, documents, and evaluates data sources for stationary area source emissions, including solid waste and agricultural burning. Area source emissions of particulate matter, sulfur dioxide, oxides of nitrogen, reactive volatile organic compounds, and carbon mon...

  14. COMBUSTION AREA SOURCES: DATA SOURCES

    EPA Science Inventory

    The report identifies, documents, and evaluates data sources for stationary area source emissions, including solid waste and agricultural burning. rea source emissions of particulate matter, sulfur dioxide, oxides of nitrogen, reactive volatile organic compounds, and carbon monox...

  15. LETTER TO THE EDITOR: Low temperature magnetic properties of frustrated pyrochlore ferromagnets Ho2Sn2O7 and Ho2Ti2O7

    NASA Astrophysics Data System (ADS)

    Matsuhira, K.; Hinatsu, Y.; Tenya, K.; Sakakibara, T.

    2000-10-01

    AC and DC magnetic susceptibilities have been measured on frustrated pyrochlore ferromagnets Ho2Sn2O7 and Ho2Ti2O7 at temperatures down to 100 mK. In the AC magnetic susceptibility, a dramatic drop of χ' (in-phase component) and a single maximum of χ'' (quadrature component) are observed at around 1 K. The frequency dependence of these peak positions indicates the presence of a slow magnetic relaxation at low temperature, whose relaxation time obeys the Arrhenius formula with the energy barrier Eb = 19.6 K and 27.5 K for Ho2Sn2O7 and Ho2Ti2O7, respectively. Strong irreversibility is also observed in the temperature dependence of the DC magnetization of Ho2Sn2O7 at 1 kOe below Tp~ 0.75 K the zero-field-cooling (ZFC) curve indicates a very sharp peak at Tp, whereas the field-cooling curve has no anomaly at Tp and increases monotonically with decreasing T. In the DC magnetization process of the ZFC state at 0.46 K, a steep increase of the moment occurs above 2 kOe, and the irreversibility disappears at around ~15 kOe where the moment ferromagnetically saturates. These results indicate a clustering of magnetic moment whose size is of the order of a few tetrahedra, consistent with a recently proposed `spin ice' model.

  16. 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.

  17. 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.

  18. A template and catalyst-free metal-etching-oxidation method to synthesize aligned oxide nanowire arrays: NiO as an example.

    PubMed

    Wei, Zhi Peng; Arredondo, Miryam; Peng, Hai Yang; Zhang, Zhou; Guo, Dong Lai; Xing, Guo Zhong; Li, Yong Feng; Wong, Lai Mun; Wang, Shi Jie; Valanoor, Nagarajan; Wu, Tom

    2010-08-24

    Although NiO is one of the canonical functional binary oxides, there has been no report so far on the effective fabrication of aligned single crystalline NiO nanowire arrays. Here we report a novel vapor-based metal-etching-oxidation method to synthesize high-quality NiO nanowire arrays with good vertical alignment and morphology control. In this method, Ni foils are used as both the substrates and the nickel source; NiCl(2) powder serves as the additional Ni source and provides Cl(2) to initiate mild etching. No template is deliberately employed; instead a nanograined NiO scale formed on the NiO foil guides the vapor infiltration and assists the self-assembled growth of NiO nanowires via a novel process comprising simultaneous Cl(2) etching and gentle oxidation. Furthermore, using CoO nanowires and Co-doped NiO as examples, we show that this general method can be employed to produce nanowires of other oxides as well as the doped counterparts. PMID:20614899

  19. A HIGH-RESOLUTION PHOTOIONIZATION AND PHOTOELECTRON STUDY OF {sup 58}Ni USING A VACUUM ULTRAVIOLET LASER

    SciTech Connect

    Shi Xiaoyu; Huang Huang; Jacobson, Brian; Chang, Yih-Chung; Ng, C. Y.; Yin Qingzhu

    2012-03-01

    In order to provide high-resolution spectroscopic data of nickel ({sup 58}Ni) and its cation ({sup 58}Ni{sup +}) for the assignment of vacuum ultraviolet (VUV) stellar spectra, we have obtained the photoionization efficiency (PIE) spectra of {sup 58}Ni by using a supersonically cooled laser ablation transition-metal beam source and a broadly tunable VUV laser in the range of 61,100-73,600 cm{sup -1}, covering the photoionization transitions: Ni{sup +} (3d{sup 92} D) <- Ni (3d{sup 8}4s{sup 23} D), Ni{sup +}(3d{sup 92} D) <- Ni(3d{sup 8}4s{sup 23} F), and Ni{sup +} (3d{sup 8}4s{sup 4} F) <- Ni(3d{sup 8}4s{sup 23} F). We have also measured the VUV laser pulsed-field-ionization-photoelectron (PFI-PE) spectra of {sup 58}Ni in these regions. The VUV-PFI-PE measurement has allowed the determination of a precise value of 61,619.89 {+-} 0.8 cm{sup -1} (7.6399 {+-} 0.0001 eV) for the ionization energy (IE) of {sup 58}Ni. Due to the narrow VUV laser optical bandwidth of 0.4 cm{sup -1} used in the present study, many complex autoionizing resonances exhibiting Fano line shape profiles are resolved in the PIE spectra. Four autoionizing Rydberg series originating from two-electron and one-electron excitations from the Ni(3d{sup 8}4s{sup 23} F{sub 4}) ground state to converge to the respective Ni{sup +}({sup 2} D{sub 3/2}) and Ni{sup +}({sup 4} F{sub J} ) (J = 9/2, 7/2, and 5/2) ion states are identified. The Rydberg analysis, along with VUV-PFI-PE measurements, has yielded highly precise IE values for the formation of these excited ionic states from the Ni(3d{sup 8}4s{sup 23} F{sub 4}) ground state. The IE values, relative photoionization cross sections, and autoionizing Rydberg resonances observed in the present study are relevant to astrophysics by enhancing the atomic database of iron group transition metal atoms and for understanding the Ni and Ni{sup +} contribution to the VUV opacity in the solar atmosphere.

  20. Inter-El Niño variability in CMIP5 models: Model deficiencies and future changes

    NASA Astrophysics Data System (ADS)

    Yun, Kyung-Sook; Yeh, Sang-Wook; Ha, Kyung-Ja

    2016-04-01

    Inter-El Niño variability, which represents the diversity in spatiotemporal evolution among El Niño events, has been identified using the first two leading modes of sea surface temperature anomalies along the equator. The first mode represents the transition from El Niño into La Niña and the second mode reveals El Niño's persistence through the following spring. Here we examine the ability of models to capture inter-El Niño variability and predict future changes due to global warming using historical and Representative Concentration Pathway 8.5 simulations of phase 5 of the Coupled Model Intercomparison Project (CMIP5). Most CMIP5 models realistically reproduce the first mode, but three fifths of the models fail to capture the second mode, with considerable intermodel diversity. The 10 best models are therefore selected according to a measurement of pattern correlation coefficients and normalized root-mean-square errors with respect to reproduction of the second mode. The results aggregated from the best models indicate that the first "transition" mode will remain unchanged from the present climate to the future climate; in contrast, the second "persistence" mode changes stochastically across the CMIP5 models. Consequently, we conclude that El Niño's transition into La Niña is the most dominant characteristic of simulated inter-El Niño variability and will remain unswayed under global warming conditions. Model deficiency in simulating El Niño's persistence is a key source of uncertainty in modeling inter-El Niño variability, resulting in difficulty predicting how certain characteristics of El Niño events may change with global warming.

  1. Chamber Study Exploring Aerosol Formation from NO3 Oxidation of α-pinene and Δ-carene under Varying HO2/RO2/NO3 Regimes

    NASA Astrophysics Data System (ADS)

    Kang, H.; Ayres, B. R.; Fry, J.; Brown, S. S.; Day, D. A.; Thompson, S.; Hu, W.; Campuzano Jost, P.; Stark, H.; Jimenez, J. L.; Ranney, A.; Ziemann, P. J.

    2014-12-01

    Although monoterpenes are pervasive in wooded environments, their reactions with nitrate radicals (NO3, a potent nighttime oxidant downwind of combustion sources) and the resulting secondary aerosol formation are not well characterized. To better understand these reactions, environmental chamber experiments have often been conducted at elevated terpene concentrations and HO2/RO2/NO3 ratios that are not representative of the real atmosphere, resulting in a range of yields. To elucidate the reasons for these varying yields, a new series of experiments were conducted with varying concentration ratios of α-pinene or Δ-carene with N2O5 (source of NO3 radical) and with/without formaldehyde in a 8000 L Teflon chamber. Formaldehyde served as a precursor for HO2 to bias the system towards HO2-RO2 reactions, elevated N2O5 caused NO3-RO2 reactions to dominate, and elevated monoterpene concentrations (but not amount reacted) favored RO2-RO2 reactions. The chamber products in the gaseous and aerosol phase were characterized using an NO3/N2O5 Cavity Ringdown Spectrometer (CRDS), an Aerodyne High-Resolution Aerosol Mass Spectrometer (AMS), a Scanning Mobility Particle Sizer (SMPS), an Ultrafine Condensation Particle Counter (UCPC), an Aerodyne High-Resolution Chemical Ionization Mass Spectrometer using Iodide ion chemistry (I- CIMS), and a chemiluminescence NOx detector. The mechanistic reasons for the starkly different SOA yield from the NO3 + α-pinene vs. NO3 + Δ-carene systems were explored in addition to differences in gas and aerosol-phase composition and yields under the varying conditions of the primary terpene RO2 radical fate.

  2. The vertical structure of OH-HO2-RO2 chemistry in the nocturnal boundary layer: A one-dimensional model study

    NASA Astrophysics Data System (ADS)

    Geyer, Andreas; Stutz, Jochen

    2004-08-01

    Elevated OH and peroxy radical levels have recently been observed in the nocturnal boundary layer (NBL). Despite the possible importance of OH for the gas phase and particulate composition, the source of these ROx radicals at night is currently unclear. To investigate the influence of vertical mixing on nocturnal ROx chemistry, calculations with a one-dimensional chemical transport model were performed. The model predicts distinct vertical profiles for all ROx radical species during the night, with a pronounced RO2 maximum aloft and maxima of HO2 and OH closer to the ground. We conceptualize our results by distinguishing three chemical regimes in the NBL: (1) In the unreactive ground layer, which only forms at high NO emissions and strong vertical stabilities, OH chemistry is suppressed by high NO levels. (2) The upper layer, located in the upper NBL, is decoupled from the NO emissions at the ground. Ozonolysis of volatile organic compounds (VOCs) leads to the formation of ˜105 molecules cm-3 of OH. The RO2 maximum develops in the lower part of the upper layer by the elevated O3/NO3 + VOC reaction rates. (3) In the reactive mixing layer, in the height interval between the upper layer and the ground layer, RO2 and HNO4 (as HO2 reservoir) from the upper layer are mixed with NO from the ground layer. The active radical propagation chain leads to distinctive maxima of HO2 and OH (up to several 106 molecules cm-3) in this layer. The OH radicals in the reactive mixing layer can contribute up to 43% to the nocturnal VOC oxidation, illustrating that OH chemistry can be important even at night. Our model simulations show that vertical transport can redistribute ROx radicals in the NBL, acting as an important radical source in the lowest few meters of the atmosphere.

  3. Synthesis and photoluminescence properties of Ho3+ doped LaAlO3 nanoparticles.

    PubMed

    Vu, Hong Ha Thi; Atabaev, Timur S; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2012-07-01

    Nanosized particles with different Ho3+ concentrations were synthesized in LaAlO3 lattices using a simple Pechini-type sol-gel method. X-ray diffraction measurements were used to investigate the structural composition and the effects of holmium dopant concentration on LaAlO3:Ho3+ crystal formation. Field-emission scanning-electron microscopy images confirm the formation of approximately spherical particles with an average size about 100 nm. The photoluminescence results yielded optimal holmium ion concentration in LaAlO3 host matrices was about 3% in mol equivalent. The mechanism that are responsible for the photoluminescence emission processes discussed with the help of Ho3+-ion Dieke energy level diagram. Power dependent slope measurements were performed to identify up-conversion photoluminescence process involved in LaAlO3:Ho3+. PMID:22966668

  4. Raman scattering of rare earth sesquioxide Ho2O3: A pressure and temperature dependent study

    NASA Astrophysics Data System (ADS)

    Pandey, Sugandha Dogra; Samanta, K.; Singh, Jasveer; Sharma, Nita Dilawar; Bandyopadhyay, A. K.

    2014-10-01

    Pressure and temperature dependent Raman scattering studies on Ho2O3 have been carried out to investigate the structural transition and the anharmonic behavior of the phonons. Ho2O3 undergoes a transition from cubic to monoclinic phase above 15.5 GPa, which is partially reversible on decompression. The anharmonic behavior of the phonon modes of Ho2O3 from 80 K to 440 K has been investigated. We find an anomalous line-width change with temperature. The mode Grüneisen parameter of bulk Ho2O3 was estimated from high pressure Raman investigation up to 29 GPa. Furthermore, the anharmonic components were calculated from the temperature dependent Raman scattering.

  5. 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.

  6. Relative rate constants for the reactions of atomic oxygen with HO2 anad OH radicals

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.

    1983-01-01

    Relative rate constants for the reactions O + HO2 - OH + O2 (1) and O + OH - H + O2 (2) were obtained by using the discharge-flow resonance fluorescence technique at 2 torr total pressure and 299 K. HO2 radicals were generated by reacting atomic hydrogen with an excess of O2. Quasi-steady-state concentrations of OH and HO2 were established in the presence of excess atomic oxygen. Observed concentration ratios, namely the ratio of the OH concentration to the HO2 concentration, resulted in a value of 1.7 + or 0.2 for k1/k2. The error limits are twice the standard deviation obtained from the data analysis. Overall experimental error is estimated to be + or - 25 percent. This result confirms earlier direct measurements of k1 and k2 which required knowledge of absolute radical or atomic oxygen concentrations.

  7. 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)

  8. Observation of hydroperoxy radical HO2 in the upper atmosphere by SMILES

    NASA Astrophysics Data System (ADS)

    Kasai, Yasuko; Lehmann, Ralph; Kuribayashi, Kouta; Sato, Tomohiro

    2016-07-01

    The HO_{2} radicals have an important role to control the oxidation capacity in the Earth and planetary atmosphere. We provide a first diurnal photo-chemical behavior of HO_{2} in the wide vertical range between stratosphere and lower thermosphere of the Earth by spectroscopic observation using a instrument optimized for the detection of minor atmospheric radical species, named Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES), from International Space Station (ISS). An unexpected behavior of HO_{2} was detected above mesopause (about 80 km) with a peak abundance after the sunset time, which was completely different from known diurnal behavior in the stratosphere and the mesosphere. We will report the photo-chemical behavior of HO_{2} in the upper atmosphere.

  9. Collective γ-vibrational bands in 165Ho and 167Er

    NASA Astrophysics Data System (ADS)

    Gervais, G.; Radford, D. C.; Shimizu, Y. R.; Cromaz, M.; DeGraaf, J.; Drake, T. E.; Flibotte, S.; Galindo-Uribarri, A.; Haslip, D. S.; Janzen, V. P.; Matsuzaki, M.; Mullins, S. M.; Nieminen, J. M.; Svensson, C. E.; Waddington, J. C.; Ward, D.; Wilson, J. N.

    1997-02-01

    The nuclear structures of 165Ho and 167Er have been investigated by means of Coulomb excitation. These nuclei excited at moderate spins exhibit γ-vibrational bands with K π = {11}/{2}-, {3}/{2}- in 165Ho and K π = {11}/{2}+ in 167Er. The γ-vibrational bands in 165Ho are found to be isospectral; heaving very nearly identical in-band γ-ray energies. Gamma-ray branching ratios are analysed to extract information on collectivity and Coriolis mixing. Experimental results are compared with calculations performed with the Cranked Shell Moedl + RPA + particle-vibration coupling and by invoking the generalized intensity relations (GIR) in the unified model scheme. Although this model explains many features of the data, puzzling aspects such as identical transition energies for the bands in 165Ho remain unexplained. The role of the K quantum number in identical bands is discussed.

  10. New Magnetic confirguration in paramagnetic phase of HoCo2

    SciTech Connect

    Bonilla, C.M.; Calvo, I.; Herrero-Albillos, J.; Figueroa, A.I.; Castan-Guerrero, C.; Bertolome, J.; Rodriguez-Velamazan, J.A.; Schmitz, D.; Weschke, E.; Paudyal, Durga; Pecharsky, Vitalij; Gschneidner Jr, Karl; Bartolome, F.; Garcia, D.

    2012-02-23

    X-ray magnetic circular dichroism (XMCD) measurements on HoCo2 reveal the inversion of Co moment at temperatures higher than the critical temperature, Tc, showing that the net magnetization under a field of the Ho and Co sublattices remain antiparallel even above Tc. The Ho moment also changes its orientation to align antiparallel to the applied field at high temperature giving rise to a new magnetic configuration in the paramagnetic regime. Transverse susceptibility (TS) and small angle neutron scattering (SANS) measurements performed above Tc indicate the existence of sizable magnetic short-range correlated regions in HoCo2. First principles calculations based on spin polarized local-density approximation, LSDA+U havebeen performed to obtain insights on the origin of the short-range correlated volume.

  11. LABORATORY MEASUREMENTS OF NiH BY FOURIER TRANSFORM DISPERSED FLUORESCENCE

    SciTech Connect

    Vallon, Raphael; Richard, Cyril; Crozet, Patrick; Wannous, Ghassan; Ross, Amanda

    2009-05-01

    Red and orange bands of laser-induced fluorescence in NiH have been recorded on a Fourier transform interferometer at Doppler resolution. The spectra show strong transitions to low-lying vibronic states which are not thermally populated in a laboratory source, and therefore do not appear in laser excitation spectra, but which would be expected to contribute significantly to any stellar spectrum. The strongest bands belong to the G[{omega}' 5/2]-X {sub 2} {sup 2}{delta}{sub 3/2}, I[{omega}' 3/2]-X {sub 2}, and {sup 2}{delta}{sub 3/2} I[{omega}' 3/2]-W {sub 1} {sup 2}{pi}{sub 3/2} systems. Measurements are reported for {sup 58}NiH, {sup 60}NiH, and {sup 62}NiH.

  12. Modeling and Characterization of the Magnetocaloric Effect in Ni2MnGa Materials

    SciTech Connect

    Nicholson, Don M; Odbadrakh, Khorgolkhuu; Rios, Orlando; Hodges, Jason P; Ludtka, Gerard Michael; Porter, Wallace D; Sefat, A. S.; Rusanu, Aurelian; Evans III, Boyd Mccutchen

    2012-01-01

    Magnetic shape memory alloys have great promise as magneto-caloric effect refrigerant materials due to their combined magnetic and structural transitions. Computational and experimental research is reported on the Ni2MnGa material system. The magnetic states of this system have been explored using the Wang-Landau statistical approach in conjunction with the Locally Self-consistent Multiple-Scattering (LSMS) method to explore the magnetic states responsible for the magnet-caloric effect in this material. The effects of alloying agents on the transition temperatures of the Ni2MnGa alloy were investigated using differential scanning calorimetry (DSC) and superconducting quantum interference device (SQUID). Neutron scattering experiments were performed to observe the structural and magnetic phase transformations at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on alloys of Ni-Mn-Ga and Ni-Mn-Ga-Cu-Fe. Data from the observations are discussed in comparison with the computational studies.

  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. Catalytic dry reforming of methane over ni-substituted hexaaluminates

    SciTech Connect

    Gardner, T; Kugler, E; Spivey, J

    2012-01-01

    CO2 re-use as an oxidant at point emission sources represents a potentially viable option to reducing CO2 footprint. CO2-CH4 reforming performance for a series of Ba0.75NiyAl12-yO19-(y = 0.2, 0.4, 0.6, 0.8 and 1.0) catalysts are examined over the temperature range 200 to 900 °C. The catalysts exhibit unique CO2 adsorption characteristics that are directly related to surface bascity and the extent of Ni-substitution. The systematic study of the Ni substitution level on both structural and catalytic effects indicates that the segregation of Ba at the surface produces an effect on surface basicity and carbon deposition. The relationship between catalyst activity and structure is characterized by EXAFS, XRD, XPS and TPR1,2.

  15. B-Ni-Ti (164)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'B-Ni-Ti (164)' with the content:

  16. Investigation of spectroscopic properties of LiNbO3:Ho3+ crystals

    NASA Astrophysics Data System (ADS)

    Demirkhanyan, Hasmik G.

    2016-01-01

    In this paper the Stark problem for Ho3+ ion (4f10 electronic configuration) in LiNbO3 crystal is solved. Main spectroscopic parameters induced by inter-Stark transitions are determined. Based on analysis of experimental and theoretical data of the main spectroscopic characteristics of LiNbO3:Ho3+ crystals, it's perceptiveness as a material for optical cooling devices is shown.

  17. The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria.

    PubMed

    Krab, K; Soos, J; Wikström, M

    1984-12-10

    In a recent communication Lehninger and co-workers (Costa, L.E., Reynaferje, B., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 4802-4811) reported values approaching 8 for the H+/O ratio of vectorial proton ejection from rat liver mitochondria respiring with succinate. Here we present a rigorous analysis of these measurements which reveals that they may significantly overestimate the true H+/O stoicheiometry. PMID:6096164

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

    PubMed

    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 V(3+) orbitals, the V(3+) 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 V(3+) 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 Ho(3+5)I8  →  (5)I7 excitations and additional excitations assigned as vibronics. These latter combined with drastic changes in Ho(3+5)I8  →  (5)I7 excitations at T N2, are indicative of a strong coupling between the Ho(3+) ions and the ligand field. This could explain the large magnetocaloric capacity shown by HoVO3. PMID:27603503

  19. 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.

  20. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1994-01-01

    Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.

  1. 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.

  2. Measured Activities of Al and Ni in gamma-(Ni) and gamma'-(Ni)3Al in the Ni-Al-Pt System

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2007-01-01

    Adding Pt to Ni-Al coatings is critical to achieving the required oxidation protection of Ni-based superalloys, but the nature of the Pt effect remains unresolved. This research provides a fundamental part of the answer by measuring the influence of Pt on the activities of Al and Ni in gamma-(Ni), gamma prime-(Ni)3Al and liquid in the Ni-Al-Pt system. Measurements have been made at 25 compositions in the Ni-rich corner over the temperature range, T = 1400-1750 K, by the vapor pressure technique with a multiple effusion-cell mass spectrometer (multi-cell KEMS). These measurements clearly show adding Pt (for X(sub Pt) less than 0.25) decreases a(Al) while increasing a(Ni). This solution behavior supports the idea that Pt increases Al transport to an alloy / Al2O3 interface and also limits the interaction between the coating and substrate alloys in the gamma-(Ni) + gamma prime-(Ni)3Al region. This presentation will review the progress of this study.

  3. Single crystal neutron diffraction study of the magnetic structure of TmNi{sub 2}B{sub 2}C

    SciTech Connect

    Sternlieb, B.; Shapiro, S.; Stassis, C.; Goldman, A.I.; Canfield, P.

    1997-02-01

    Neutron diffraction techniques have been used to study the magnetic structure of single crystals of the magnetic superconductor (T{sub c} {congruent} 11K) TmNi{sub 2}B{sub 2}C. We find that below approximately 1.5K the magnetic moments order in an incommensurate spin wave with propagation vector q{sub m} = q{sub m} (a* +b*) (or q{sub m} = q{sub m} (a* + b*)) with q{sub m} = 0.094 {+-} 0.001. The spin wave is transverse with the moments aligned along the c-axis, and the observation of relatively intense higher order harmonics shows that the modulation is not purely sinusoidal but considerably squared. This incommensurate magnetic structure, which coexists with superconductivity below T{sub N} {congruent} 1.5K, is quite different from those observed in the magnetic superconductors HoNi{sub 2}B{sub 2}C and ErNi{sub 2}B{sub 2}C. The origin of diffraction peaks observed in scans parallel to a* is briefly discussed.

  4. 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.

  5. Comparative studies of microwave absorption in the singlet paramagnets HoVO{sub 4} and HoBa{sub 2}Cu{sub 3}O{sub x} in strong pulsed magnetic fields

    SciTech Connect

    Kazei, Z. A. Snegirev, V. V.; Goaran, M.; Kozeeva, L. P.; Kameneva, M. Yu.

    2008-03-15

    Microwave absorption in the tetragonal singlet paramagnets HoVO{sub 4} (zircon structure) and HoBa{sub 2}Cu{sub 3}O{sub x} (x {approx} 6, layered perovskite structure) is studied and compared in pulsed magnetic fields up to 40 T at low temperatures. These paramagnets are characterized by a singlet-doublet scheme of the low-lying levels of the Ho{sup 3+} ion in a crystal field. In a magnetic field directed along the tetragonal axis, HoVO{sub 4} exhibits resonance absorption lines at wavelengths of 871, 406, and 305 {mu}m, which correspond to electron transitions between the low-lying levels of the Ho{sup 3+} ion in the crystal field. The positions and intensities of these absorption lines in HoVO{sub 4} are well described in terms of the crystal-field formalism with the well-known interaction parameters. The absorption spectra of HoBa{sub 2}Cu{sub 3}O{sub x} at a wavelength of 871 {mu}m exhibit broad resonance absorption lines against the background of strong nonresonance absorption. The effects of low-symmetry (orthorhombic, monoclinic) crystal-field components, the deviation of a magnetic field from a symmetry axis, and various pair interactions on the absorption spectra of the HoVO{sub 4} and HoBa{sub 2}Cu{sub 3}O{sub x} crystals are discussed.

  6. Comparison of urinary calculus fragmentation during Ho:YAG and Er:YAG lithotripsy

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Lee, Ho; Teichman, Joel H.; Welch, A. J.

    2005-04-01

    We compared urinary calculus fragmentation with long pulsed Ho:YAG (λ= 2.12 μm) versus Er:YAG (λ = 2.94 μm) lasers. We measured the ablation width, depth, volume and efficiency as a function of pulse energy from calculus threshold energy to clinical energy typically used for Ho:YAG laser lithotripsy. Ablation effects were evaluated for three types of urinary calculi (calcium oxalate monohydrate, cystine, and uric acid), for single and multiple pulses applied at various optical energy levels. By means of comparing laser-induced crater topography and ablation volume for each stone type, the feasibility of Er:YAG laser lithotripsy was appraised. The Er:YAG laser pulse energy generated deeper and narrower crater shapes with relatively smooth contours whereas the Ho:YAG laser produced shallower and wider craters with irregular shapes. In terms of multiple pulses ablation, the Er:YAG produced larger ablation volume than Ho:YAG. The deeper crater induced by the Er:YAG was attributed to the higher absorption coefficient of stones at the 2.94 μm wavelength, and widening of crater by Ho:YAG was perhaps caused by lateral expansion of ablated material. Comparing the ablation efficiency, Er:YAG was superior to Ho:YAG for both single and five-pulses.

  7. Nd(3+)-Sensitized Ho(3+) Single-Band Red Upconversion Luminescence in Core-Shell Nanoarchitecture.

    PubMed

    Chen, Daqin; Liu, Lu; Huang, Ping; Ding, Mingye; Zhong, Jiasong; Ji, Zhenguo

    2015-07-16

    A strategy to achieve 808 nm excited single-band red upconversion luminescence of Ho(3+) via the core-shell nanoarchitecture design was provided. Specifically, the synthesized Yb/Ho/Ce: NaGdF4@Yb/Nd: NaYF4 active-core@active-shell nanoparticles were evidenced to enable high-content doping of Nd(3+) (∼10 mol %) in the shell layer and, thus, markedly enhance red upconversion emission from Ho(3+) activators in the core with the assistance of spatially confined doping of Nd(3+) ions and efficient energy transfer of Nd(3+) → Yb(3+)(shell) → Yb(3+)(core) → Ho(3+). Importantly, introducing Ce(3+) into the core was beneficial to the competition of radiation transitions from the two intermediate excited states of Ho(3+): (5)S2,(5)F4 (green-emitting) and Ho(3+): (5)F5 (red-emitting), which induced great enhancement in the red to green intensity ratio and ultimately intense single-band red upconversion emission. We believe that this preliminary study will provide an important advance in developing luminescent markers suitable for biolabeling applications. PMID:26266869

  8. HoBi-like viruses--the typical 'atypical bovine pestivirus'.

    PubMed

    Bauermann, Fernando V; Ridpath, Julia F

    2015-06-01

    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 suggest that these viruses may be endemic at least in parts of South America and Asia. The clinical presentations in cattle, described in field outbreaks and controlled studies, are similar to those associated with BVDV and range from subclinical to mild clinical signs, sporadically associated with reproductive losses, respiratory illness and hemorrhagic syndrome. The complete host range of HoBi-like virus is unknown, but data suggest higher adaptation of HoBi-like viruses to ruminants than swine. Acute infections, characterized by mild clinical signs, such as low-grade pyrexia and leukopenia, have been observed in both cattle and sheep. Virus has been isolated from nasal swabs indicating that virus was being shed. While seroconversion has been observed in pigs, no clinical presentation or viral shedding was evident following inoculation. While some commercial BVDV diagnostic tests may detect HoBi-like viruses, these tests do not differentiate between BVDV and HoBi-like viruses. The differentiation of BVDV and HoBi-like viruses is critical to the design of surveillance programs for these viruses. PMID:26050574

  9. First evidence of middle atmospheric HO2 response to 27 day solar cycles from satellite observations

    NASA Astrophysics Data System (ADS)

    Wang, Shuhui; Zhang, Qiong; Millán, Luis; Li, King-Fai; Yung, Yuk L.; Sander, Stanley P.; Livesey, Nathaniel J.; Santee, Michelle L.

    2015-11-01

    HO2 and OH, also known as HOx, play an important role in controlling middle atmospheric O3. Due to their photochemical production and short chemical lifetimes, HOx are expected to respond rapidly to solar irradiance changes, resulting in O3 variability. While OH solar cycle signals have been investigated, HO2 studies have been limited by the lack of reliable observations. Here we present the first evidence of HO2 variability during solar 27 day cycles by investigating the recently developed HO2 data from the Aura Microwave Limb Sounder (MLS). We focus on 2012-2015, when solar variability is strong near the peak of Solar Cycle 24. The features of HO2 variability, with the strongest signals at 0.01-0.068 hPa, correlate well with those of solar Lyman α. When continuous MLS OH observations are not available, the new HO2 data could be a promising alternative for investigating HOx variability and the corresponding impacts on O3 and the climate.

  10. GEC-targeted HO-1 expression reduces proteinuria in glomerular immune injury.

    PubMed

    Duann, Pu; Lianos, Elias A

    2009-09-01

    Induction of heme oxygenase (HO)-1 is a key defense mechanism against oxidative stress. Compared with tubules, glomeruli are refractory to HO-1 upregulation in response to injury. This can be a disadvantage as it may be associated with insufficient production of cytoprotective heme-degradation metabolites. We, therefore, explored whether 1) targeted HO-1 expression can be achieved in glomeruli without altering their physiological integrity and 2) this expression reduces proteinuria in immune injury induced by an anti-glomerular basement membrane (GBM) antibody (Ab). We employed a 4.125-kb fragment of a mouse nephrin promoter downstream to which a FLAG-tagged hHO-1 cDNA sequence was inserted and subsequently generated transgenic mice from the FVB/N parental strain. There was a 16-fold higher transgene expression in the kidney than nonspecific background (liver) while the transprotein immunolocalized in glomerular epithelial cells (GEC). There was no change in urinary protein excretion, indicating that GEC-targeted HO-1 expression had no effect on glomerular protein permeability. Urinary protein excretion in transgenic mice with anti-GBM Ab injury (days 3 and 6) was significantly lower compared with wild-type controls. There was no significant change in renal expression levels of profibrotic (TGF-beta1) or anti-inflammatory (IL-10) cytokines in transgenic mice with anti-GBM Ab injury. These observations indicate that GEC-targeted HO-1 expression does not alter glomerular physiological integrity and reduces proteinuria in glomerular immune injury. PMID:19587144

  11. Solid speciation and availability of nickel and chromium in Ni mining spoils

    NASA Astrophysics Data System (ADS)

    Raous, Sophie; Garnier, Jérémie; Sterckeman, Thibaul; Echevarria, Guillaume; Becquer, Thierry; Thomas, Fabien

    2010-05-01

    Nickel mining of ultramafic laterites generates different types of wastes, topsoils and ores that are too poor in Ni to be currently processed. These are mixed and stored on heaps which could be a potential source of Ni and Cr pollution. Chemical reactivity of the main metal bearing phases present in the mining spoils of Goiás (Brasil) was investigated. Principally a silicated 'saprolite' material and a Fe-oxide rich limonitic material were isolated from the wastes. Their total Ni and Cr content are high, respectively for Ni and Cr : 7,170 and 54,970 mg kg-1 in limonite and 12,200 and 12,650 mg kg-1 in saprolite. The main metal-bearing minerals, identified and localized using XRD, TEM-EDX, Raman spectroscopy and Mossbaüer spectrometry are well-crystallized minerals: goethite (75%), hematite (13%) and chromite in limonite and ferruginous smectite, talc and chromite in saprolite. Single and sequential extractions showed that the amounts of 1M KCl exchangeable Ni and Cr reached respectively 7.1% and 0.03% of total contents in saprolite. Moreover, Cr(VI) extraction by KH2PO4 showed that more than 2% (980 mg kg-1) of total Cr was under this labile toxic form in limonite. This study allowed us to determine the main reactions controlling the Ni and Cr mobility in the spoils i.e. Ni2+ cationic exchange in saprolitic spoil and CrO32- surface complexation in limonitic spoil. This study allowed us to demonstrate the need of chemical rehabilitation of mining wastes in order to avoid the dispersion of the high contents of Ni and Cr available. It constitutes the system definition needed to predict the Cr and Ni mobility in ultramafic mining spoils.

  12. A Note on Friedmann Equation of FRW Universe in Deformed Hořava—Lifshitz Gravity from Entropic Force

    NASA Astrophysics Data System (ADS)

    Wei, Shao-Wen; Liu, Yu-Xiao; Wang, Yong-Qiang

    2011-09-01

    With entropic interpretation of gravity proposed by Verlinde, we obtain the Friedmann equation of the Friedmann—Robertson—Walker universe for the deformed Hořava—Lifshitz gravity. It is shown that, when the parameter of Hořava—Lifshitz gravity ω → ∞, the modified Friedmann equation will go back to the one in Einstein gravity. This results may imply that the entropic interpretation of gravity is effective for the deformed Hořava—Lifshitz gravity.

  13. Metalation of cyclic pseudopeptidic thiosulfinates with Ni(II) and Zn(II) after ring opening: a mechanistic investigation.

    PubMed

    Galardon, Erwan; Bourles, Emilie; Artaud, Isabelle; Daran, Jean-Claude; Roussel, Pascal; Tomas, Alain

    2007-05-28

    Thiosulfinates are an emerging class of oxidized sulfur species that are frequently supposed to be involved in biochemical processes. Reaction of 12- and 10-membered ring pseudopeptidic thiosulfinates 1a (4,4,7,7-tetramethyl-1,3,4,7,8,10-hexahydro-5,6,1,10-benzodithiadiazacyclododecine-2,9-dione 5-oxide) and 1b (3,3,6,6-tetramethyl-1,8-dihydro-4,5,1,8-benzodithiadiazecine-2,7(3H,6H)-dione 4-oxide) with a Ni(II) salt leads after ring cleavage under alkaline conditions to the isolation of diamidato/thiolato/sulfinato complexes. These two thiolato/sulfinato complexes of nickel, which can also be prepared by dioxygen oxidation of the parent diamidato/dithiolato complexes, were characterized by X-ray crystallography. They show a square-planar geometry with a S-bonded sulfinato ligand. A similar reaction between 1b and a Zn(II) salt leads to a thiolato/sulfinato complex with an O-bonded sulfinate via the intermediate formation of a mixed thiolato/sulfinic ester. On the basis of 1H NMR, IR, and mass analyses, the sulfinic ester in the intermediate is proposed to be O-bonded to the zinc center. Then, an in-depth study of the cleavage of these thiosulfinates with the oxyanions RO- and HO- was performed. This led, after trapping of the open species with CH3I, to the identification of three polyfunctionalized products containing a methyl thioether, with either an isothiazolidin-3-one S-oxide, a methyl sulfone, or a methyl sulfinic ester. All of these products arise from a selective nucleophilic attack at the sulfinyl sulfur, promoted either directly by RO- or HO- or by an internal peptidic nitrogen of the thiosulfinate after deprotonation with RO- or HO-. PMID:17465540

  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. PMID:23207298

  15. Ho:YAG laser arthroscopy of the knee

    NASA Astrophysics Data System (ADS)

    Sisto, Domenick J.; Blazina, Martin E.; Hirsh, Linda C.

    1994-09-01

    The HO:YAG laser is a near-contact laser with a capacity to ablate or cut tissues. The ablation function allows the surgeon to remove meniscal tissue, lyse and resect adhesions, melt loose bodies, and dissolve inflamed synovium. The cutting function of the laser is utilized to perform a lateral release or resect torn menisci. The laser can also be utilized to drill holes in Grade IV chondromalacic lesions to initiate a healing response. The laser has been embraced by orthopaedic surgeons because of its shape and versatility. The tip is only 2 mm wide and can be delivered into the tight posterior compartments of the knee with no damaging contact with the articular surfaces. The laser coagulates as it works and bleeding is minimized. The laser can function both as a cutting and ablating tool. The laser can also drill holes into subchondral bone to, hopefully, initiate a healing response.

  16. 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.

  17. The impact of Ni on the physiology of a Mediterranean Ni-hyperaccumulating plant.

    PubMed

    Roccotiello, Enrica; Serrano, Helena Cristina; Mariotti, Mauro Giorgio; Branquinho, Cristina

    2016-06-01

    High nickel (Ni) levels exert toxic effects on plant growth and plant water content, thus affecting photosynthesis. In a pot experiment, we investigated the effect of the Ni concentration on the physiological characteristics of the Ni hyperaccumulator Alyssoides utriculata when grown on a vermiculite substrate in the presence of different external Ni concentrations (0-500 mg Ni L(-1)). The results showed that the Ni concentration was higher in leaves than in roots, as evidenced by a translocation factor = 3 and a bioconcentration factor = 10. At the highest concentration tested (500 mg Ni L(-1)), A. utriculata accumulated 1100 mg Ni per kilogram in its leaves, without an effects on its biomass. Plant water content increased significantly with Ni accumulation. Ni treatment did not, or only slightly, affected chlorophyll fluorescence parameters. The photosynthetic efficiency (FV/FM) of A. utriculata was stable between Ni treatments (always ≥ 0.8) and the photosynthetic performance of the plant under Ni stress remained high (performance index = 1.5). These findings support that A. utriculata has several mechanisms to avoid severe damage to its photosynthetic apparatus, confirming the tolerance of this species to Ni under hyperaccumulation. PMID:26983814

  18. Investigation on the Interactions of NiCR and NiCR-2H with DNA

    PubMed Central

    Chitranshi, Priyanka; Chen, Chang-Nan; Jones, Patrick R.; Faridi, Jesika S.; Xue, Liang

    2010-01-01

    We report here a biophysical and biochemical approach to determine the differences in interactions of NiCR and NiCR-2H with DNA. Our goal is to determine whether such interactions are responsible for the recently observed differences in their cytotoxicity toward MCF-7 cancer cells. Viscosity measurement and fluorescence displacement titration indicated that both NiCR and NiCR-2H bind weakly to duplex DNA in the grooves. The coordination of NiCR-2H with the N-7 of 2′-deoxyguanosine 5′-monophosphate (5′-dGMP) is stronger than that of NiCR as determined by 1H NMR. NiCR-2H, like NiCR, can selectively oxidize guanines present in distinctive DNA structures (e.g., bulges), and notably, NiCR-2H oxidizes guanines more efficiently than NiCR. In addition, UV and 1H NMR studies revealed that NiCR is oxidized into NiCR-2H in the presence of KHSO5 at low molar ratios with respect to NiCR (≤4). PMID:20671951

  19. Measurement of pernitric acid (HO2NO2) using chemical ionization mass spectrometry (CIMS) with I-·H2O as the reagent ions: instrumentation and observations

    NASA Astrophysics Data System (ADS)

    Chen, D.; Huey, L. G.; Tanner, D.; Ng, N. L.; Li, J.; Dibb, J. E.; Wang, Y.

    2015-12-01

    Peroxynitric acid (HO2NO2) is formed by the association reaction of HO2 and NO2, which couples both the HOx (HO2+OH) and NOx (=NO2+NO) families. The thermal decomposition at higher temperatures is sufficiently fast that HO2NO2 is in steady state with HO2 and NO2. This allows HO2 levels to be inferred from HO2NO2 observations. In Polar Regions and higher altitudes, significant levels of HO2NO2 can build up and influences local HOx and NOx photochemistry. Here, we present an in situ measurement technique of HO2NO2 based on chemical ionization mass spectrometry (CIMS) using the reagent ion I- and its hydrated form I-·H2O, together with our calibration technique for HO2NO2 measurements. We will also present observations of HO2NO2: (1) in a polar boundary layer on top of the Greenland Ice Sheet during summer 2011, and (2) in an urban boundary layer in metropolitan Atlanta during winter 2014. The local chemistry of HO2NO2 at Summit will be evaluated. The local HO2 in Atlanta will be inferred and assessed with models.

  20. New technique for prostatectomy using Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Daidoh, Yuichiro; Arai, Tsunenori; Murai, Masaru; Nakajima, Akio; Tsuji, Akira; Odajima, Kunio; Nakajima, Fumio; Kikuchi, Makoto; Nakamura, Hiroshi

    1994-05-01

    To develop a new transperineal laser prostatectomy through a biopsy needle, we determined the efficiency of a pulsed Nd:YAG laser irradiation for canine prostate. The Ho:YAG laser ((lambda) equals 2.1 micrometers ) may induced stress-wave to destroy the small vessels in prostate. After the exposure of the canine prostate, it was punctured by the needle. A quartz fiber of which core-diameter was 200 or 400 micrometers was inserted into the 18 G needle. The irradiation fluence was set to 150 - 600 J/cm2 and repetition rate was kept at 2 Hz. The cross-section of the irradiated portion of the prostate extracted immediately after the irradiation showed dark-colored hemorrhage layer around the ablation tract with 1 - 2 mm thickness. Some hemorrhage was histologically seen in stoma and gland in the irradiated prostate. In the case of 150 - 175 J/cm2 in the irradiation fluence, the irradiated portion of the prostate was found in the wedge-shaped area with brown color at one week after the irradiation. The lymphocytes infiltrating into the wedge-shaped zone were found. The wedge- shaped zone spread over the prostate and the change of urethral mucosa was minimum at one month after the irradiation. In the case of 500 - 600 J/cm2 irradiation, the paraurethral cavity was made at one month after the irradiation. The histological examination showed that the hemorrhage and subsequent histological changes may be caused by the laser induced stress-wave rather than thermal effect. Our results suggest that transperineal irradiation of pulsed Ho:YAG might offer an effective treatment for benign prostatic hyperplasia with the minimal damage to the urethral mucosa.

  1. 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. PMID:12347640

  2. High-nuclearity homometallic iron and nickel clusters: Fe22 and Ni24 complexes from the use of N-methyldiethanolamine.

    PubMed

    Foguet-Albiol, Dolos; Abboud, Khalil A; Christou, George

    2005-09-14

    The use of N-methyldiethanolamine (mdaH2) in reactions with Fe(III) and Ni(II) sources has led to Fe22 and Ni24 products; the clusters are the highest and second-highest, respectively, homometallic clusters for these metals to date, and possess S = 0 and S = 6 ground states, respectively. PMID:16113722

  3. A threonine stabilizes the NiC and NiR catalytic intermediates of [NiFe]-hydrogenase.

    PubMed

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-03-27

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production. PMID:25666617

  4. A Threonine Stabilizes the NiC and NiR Catalytic Intermediates of [NiFe]-hydrogenase*

    PubMed Central

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L.; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-01-01

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production. PMID:25666617

  5. Production, Quality Control and Biological Evaluation of 166Ho-PDTMP as a Possible Bone Palliation Agent

    PubMed Central

    Zolghadri, Samaneh; Jalilian, Amir Reza; Naseri, Zohreh; Yousefnia, Hassan; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad; Afarideh, Hossein

    2013-01-01

    Objective(s): In this study, 166Ho-1,2-propylene di-amino tetra(methy1enephosphonicAcid) (166Ho-PDTMP) complex was prepared as a bone palliation agent. Materials and Methods: The complex was successfully prepared using an in-house synthesized EDTMP ligand and 166HoCl3. Ho-166 chloride was obtained by thermal neutron irradiation (1 × 1013 n.cm-2.s-1) of natural Ho(NO3)3 samples followed by radiolabeling and stability studies. Biodistribution in wild type rats was also peformed. Results: The complex was prepared with the specific activity of 278 GBq/mg and high radiochemical purity (>99%, checked by ITLC). 166Ho-PDTMP complex was stabilized in the final preparation and in the presence of human serum (>90%) up to 72 hr. The biodistribution of 166Ho-PDTMP in wild-type rats demonstrated significant bone uptake was up to 48 hr compared to 166HoCl3. Conclusion: The produced 166Ho-PDTMP properties suggest a possible new bone palliative therapeutic to overcome the metastatic bone pains. PMID:23826495

  6. Preparation and spectroscopic characterization of two HoCl 3-galactitol complexes and one ErCl 3-galactitol complex

    NASA Astrophysics Data System (ADS)

    Hua, Xiaohui; Pan, Qinghua; Yu, Lei; Xue, Junhui; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Li, Weihong; Wang, Zheming; Wu, Jinguang; Liu, Kexin; Chen, Jia'er

    2011-07-01

    The interactions between metal ions and hydroxyl groups of carbohydrates are important for their possible biological activities. Here two HoCl 3-galactitol complexes ([Ho(galac)(H 2O) 3)]Cl 3·0.5galac) (HoG(I)) and ([Ho 2(galac)(H 2O) 12)]Cl 6·2H 2O) (HoG(II))) and one ErCl 3-galactitol complex ([Er(galac)(H 2O) 3)]Cl 3·0.5galac)(ErG)) were prepared and characterized. The possible structures of HoG(I) and ErG were deduced from FTIR, elemental analysis, ESI-MS, FIR, THz and TGA results. It is suggested that Ho 3+ or Er 3+ is 9-coordinated with six hydroxyl groups from two galactitol molecules and three water molecules, and another galactitol molecule is hydrogen-bonded in HoG(I) and ErG and the ratio of metal to ligand is 1:1.5. The structure of HoG(II) was determined by FTIR and X-ray diffraction analyses. The results demonstrate that lanthanide ions with galactitol may form two compounds in a system and different topological structures can be obtained.

  7. Effect of ZnX (X=F2 and Cl2) as modifier on luminescence properties of Ho3+/Yb3+ doped tellurite glasses.

    PubMed

    Joshi, C; Kumar, K; Rai, S B

    2011-06-01

    Optical absorption and photoluminescent properties of Ho(3+)/Yb(3+) co-doped tellurite and zinc halide tellurite glasses are investigated. The effect of zinc halides as modifier on the luminescence properties of above mentioned samples has been explored. Two intense upconversion emission bands centered at 546 ((5)F(4), (5)S(2)→(5)I(8)) and 660 ((5)F(5)→(5)I(8)) nm are observed when samples are excited by 976 nm radiation. Zinc halides act as quencher when 976 nm excitation source is used. The up and downconversion emission spectra are recorded with 532 nm excitation source also. In this case also, zinc halides do not show any improvement. The dependence of upconversion intensities on excitation power and temperature is discussed. The power dependence study shows a quadratic dependence of fluorescence intensity on the excitation power while decrement in emission intensity of different transitions at different rates is observed in temperature dependence study. The possible upconversion mechanisms are also discussed in order to understand the energy transfer between Yb(3+) and Ho(3+) ions. PMID:21398172

  8. Electromigration effect of Ni electrodes on the resistive switching characteristics of NiO thin films

    NASA Astrophysics Data System (ADS)

    Lee, C. B.; Kang, B. S.; Lee, M. J.; Ahn, S. E.; Stefanovich, G.; Xianyu, W. X.; Kim, K. H.; Hur, J. H.; Yin, H. X.; Park, Y.; Yoo, I. K.; Park, J.-B.; Park, B. H.

    2007-08-01

    The effects of Ni and Ni0.83Pt0.17 alloy electrodes on the resistance switching of the dc-sputtered polycrystalline NiO thin films were investigated. The initial off-state resistances of the films were similar to that of Pt /NiO/Pt film. However, after the first cycle of switching, the off-state resistance significantly decreased in the films with Ni in the electrode. It can be attributed to the migration of Ni from electrodes to the NiO films. The improvement in data dispersion of switching parameters is explained in terms of the decrease of the effective thickness of the films resulting from the migration of Ni.

  9. Precursor approach to lanthanide dioxo monocarbodiimides Ln2O2CN2 (Ln=Y, Ho, Er, Yb) by insertion of CO2 into organometallic Ln-N compounds.

    PubMed

    Zeuner, Martin; Pagano, Sandro; Schnick, Wolfgang

    2008-01-01

    We present two organometallic precursor approaches leading to the hitherto-unknown dioxo monocarbodiimides (Ln(2)O(2)CN(2)) of the late lanthanides Ho, Er, and Yb as well as yttrium. One involves insertion of CO(2), and the other one is a straightforward route using a molecular single-source precursor. To this end the reactivity of the activated amido lanthanide compound [(Cp(2)ErNH(2))(2)] towards carbon dioxide absorption under supercritical conditions was studied. Selective insertion of CO(2) into the amido complex yielded the single-source precursor [Er(2)(O(2)CN(2)H(4))Cp(4)], which was characterized by vibrational spectroscopy and thermal and elemental analyses. Ammonolysis of this amorphous compound at 700 degrees C affords Er(2)O(2)CN(2). To gain deeper insight into the structural characteristics of the amorphous precursor, a similar molecular carbamato complex was synthesized and fully characterized. X-ray structure analysis of the dimeric complex [Cp(4)Ho(2){mu-eta(1):eta(2)-OC(OtBu)NH}] shows an unusual bonding mode of the tert-butylcarbamate ligand, which acts as both a bridging and side-on chelating group. Ammonolysis of this compound also yielded dioxo monocarbodiimides, and therefore the crystalline carbamato complex turned out to be an alternative precursor for the straightforward synthesis of Ln(2)O(2)CN(2). Analogously, the dioxo monocarbodiimides of Y, Ho, Er, and Yb were synthesized by this route. The crystal structures were determined from X-ray powder diffraction data and refined by the Rietveld method (Ln=Ho, Er). Further spectroscopic characterization and elemental analysis evidenced the existence of phase-pure products. The dioxo monocarbodiimides of holmium and erbium crystallize in the trigonal space group P[over]3m1. According to X-ray powder diffraction, they adopt the Ln(2)O(2)CN(2) (Ln=Ce-Gd) structure type. PMID:18058884

  10. Radioanalytical studies of fallout 63Ni.

    PubMed

    Holm, E; Roos, P; Skwarzec, B

    1992-01-01

    Fallout of Nickel-63 (T1/2 = 100 a) produced in small amounts at nuclear weapon tests following the neutron activation of weapon construction material was investigated by studying carpets of lichen collected during 1961 to 1988 at the Lake Rogen district in central Sweden (62.3 degrees N, 12.4 degrees E). The maximal level of 63Ni in the lichen carpet, which occurred in 1964, was about 0.6 Bq kg-1, dry weight, and decreased to 0.1 Bq kg-1 in 1988. The deposition pattern for 63Ni was similar to other fallout radionuclides such as 137Cs, 90Sr and 239 + 240Pu. The concentrations of stable Ni were relatively constant at 0.5 to 1.0 microgram g-1 throughout the years resulting in, for example, a specific activity (63Ni/stable Ni) of 0.5 Bq mg-1 in 1964 and 0.1 Bq mg-1 in 1988. The total area content of 63Ni was estimated to be 1.0 Bq m-2 and the activity ratio 63Ni/60Co was estimated to be 0.03 in 1966. The Chernobyl accident in April 1986 did not significantly increase the levels of 63Ni. For the measurement of these extremely low-levels of 63Ni, 200 g of dry material (about 1 kg fresh) were ashed and leached with aqua regia after hydroxides had been precipitated with ammonia, leaving Ni in the aqueous phase. Nickel was extracted as a dimethylglyoxime complex by chloroform and back-extracted with HCl. Finally, Ni was electroplated onto copper discs from an ammonium sulfate medium at high pH. The radiochemical yield was determined by atomic absorption spectrometry of stable Ni before and after electrodeposition.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1310303

  11. [166Dy]Dy/166Ho hydroxide macroaggregates: an in vivo generator system for radiation synovectomy.

    PubMed

    Ferro-Flores, G; Hernández-Oviedo, O; Arteaga de Murphy, C; Tendilla, J I; Monroy-Guzmán, F; Pedraza-López, M; Aldama-Alvarado, K

    2004-12-01

    Radiation synovectomy is an effective treatment in patients suffering from inflammatory-rheumatoid and degenerative joint diseases. The aim of this work was to examine the feasibility of preparing dysprosium-166 (166Dy)/holmium-166(166Ho) hydroxide macroaggregates ([166Dy]Dy/166Ho-HM) as an in vivo generator for radiation synovectomy evaluating whether the stability of 166Dy-HM and 166Ho-HM complexes is maintained when the daughter 166Ho is formed. The Monte Carlo (MCNP4B) theoretical depth dose profile for the in vivo [166Dy]Dy/166Ho generator system in a joint model was calculated and compared with that produced by 90Y, 153Sm and 166Ho. 166Dy was obtained by neutron irradiation of enriched 164Dy2O3 in a Triga Mark III reactor. Macroaggregates were prepared by reaction of [166Dy]DyCl3 with 0.5 M NaOH in an ultrasonic bath. [166Dy]Dy/166Ho-HM was obtained with radiochemical purity >99.5% and with the majority of particles in the 2-5 microm range. In vitro studies demonstrated that the radio-macroaggregates are stable in saline solution and human serum without a significant change in the particle size over 14 d, suggesting that no translocation of the daughter nucleus occurs subsequent to beta- decay of 166Dy. Biological studies in normal rats demonstrated high retention in the knee joint even 7 d after [166Dy]Dy/166Ho-HM administration. The Monte Carlo (MCNP4B) theoretical depth dose profiles in a joint model, showed that the in vivo [166Dy]Dy/166Ho generator system would produce 25% and 50% less radiation dose to the articular cartilage and bone surface, respectively, than that produced by 90Y or pure 166Ho in a treatment with the same therapeutic dose to the synovium surface. Despite that 153Sm showed the best depth dose profile sparing doses to healthy tissues, the use of 166Dy could provide the advantage of being applied in patients that cannot be reached within a few hours from a nuclear reactor and to produce less radiation exposure to the medical personnel

  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. Composite Ni/NiO-Cr2O3 Catalyst for Alkaline Hydrogen Evolution Reaction

    SciTech Connect

    Bates, MK; Jia, QY; Ramaswamy, N; Allen, RJ; Mukerjee, S

    2015-03-12

    We report a Ni-Cr/C electrocatalyst with unpreeedented massactivity for the hydrogen evolution reaction (HER). in alkaline electrolyte. The HER Oietics of numerous binary and ternary Ni-alloys and composite Ni/metal-euride/C samples were evaluated in aquebus 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni-Cr materials which exhibit metallic Ni as well as NiOx and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to munerous binary dor ternary Ni-alloys, inCluding Ni Mg materials. It is likely that at adjacent Ni/NiOx sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a, sink for the H-ads, intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiO content and that the Cr2O3 appears to stabilize the composite NiO component-under HER conditions (where NiOx would typically be reduced to metallic Ni-0). Furthermore, in contrast to Pt, the Ni(O-x)/Cr2O3 catalyst appears resistant to poisoning by the anion.exchange ionomer (AEI), a serloua consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a: detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI.

  14. Microstructure and superelasticity of NiS/TiNi composite electrode

    NASA Astrophysics Data System (ADS)

    Kim, Han-seong; Cho, Gyu-bong; Kim, Ki-won; Cho, Kwon-koo; Liu, Yinong; Nam, Tae-hyun

    2007-07-01

    Surface Ni sulfides layers were formed on the surface of a Ti-50.0Ni alloy by reacting sulfur and Ni film deposited on the alloy, and then microstructures, transformation behavior, shape memory characteristics, superelasticity and electrochemical properties of a Ti-50.0Ni(at%) alloy with the sulfides were investigated. When Ni film deposited on a Ti-50.0Ni alloy was annealed under the sulfur pressure of 100 kPa at 623 K, sulfides layers consisted of NiS and NiS 1.97 were formed. When annealing was made at 648 K annealing with annealing time less than 0.9 ks, sulfides layers consisted of NiS and NiS 1.97 were formed also, while only NiS 1.97 was formed when it was made for 1.8 ks. When annealing was made at 673 K annealing with annealing time longer than 0.9 ks, only NiS 1.97 was formed. A Ti- 50.0Ni(at%) alloy with surface NiS 1.97 layer showed the two-stage B2-R-B19' transformation behavior, the perfect shape memory effect and a partial superelasticity with a superelastic recovery ratio of 78 %. NiS 1.97 cathode showed a clear discharge behavior with multi voltage plateaus. Discharge capacity of NiS 1.97 cathode decreased abruptly with increasing number of cycles up to 3, above which it decreased gradually.

  15. Selection Sources.

    ERIC Educational Resources Information Center

    Kerby, Ramona

    2002-01-01

    Discusses library collection development by school library media specialists and describes selection sources for new books and materials; retrospective selection sources for materials published in preceding years; and an acquisition source. Provides an overview of the selection process and includes 10 suggestions for selection. (LRW)

  16. Nonpoint Sources.

    ERIC Educational Resources Information Center

    Browne, F. X.

    1978-01-01

    Presented a literature review of nonpoint source effects on water quality and pollution covering: (1) water quality effects; (2) watershed studies; (3) nonpoint source models; and nonpoint source controls. A list of 122 references published in 1976 and 1977 is also presented. (HM)

  17. Ni speciation in tea infusions by monolithic chromatography--ICP-MS and Q-TOF-MS.

    PubMed

    Ščančar, Janez; Zuliani, Tea; Žigon, Dušan; Milačič, Radmila

    2013-02-01

    For humans, Ni is not considered to be an essential trace element. Its compounds, at levels present in foodstuffs and drinks, are generally considered to be safe for consumption, but for individuals who already suffer from contact allergy to Ni and may be subject to develop systemic reactions from its dietary ingestion, dietary exposure to Ni must be kept under control. Being the second most popular beverage, tea is a potential source of dietary Ni. Present knowledge on its speciation in tea infusions is poor. Therefore, complete speciation analysis, consisting of separation by liquid chromatography using a weak CIM DEAE-1 monolithic column, "on-line" detection by inductively coupled plasma mass spectrometry (ICP-MS) and "off-line" identification of ligands by hybrid quadrupole time-of-flight mass spectrometry (Q-TOF MS), was implemented for the first time to study Ni speciation in tea infusions. Total concentrations of Ni in dry leaves of white, green, oolong and black tea (Camellia sinensis) and flowers of herbal chamomile (Matricaria chamomilla) and hibiscus (Hibiscus sabdariffa) tea were determined after microwave digestion by ICP-MS. They lay between 1.21 and 14.4 mg kg(-1). Good agreement between the determined and the certified values of the Ni content in the standard reference material SRM 1573a tomato leaves confirmed the accuracy of the total Ni determination. During the infusion process, up to 85 % of Ni was extracted from tea leaves or flowers. Separation of Ni species was completed in 10 min by applying aqueous linear gradient elution with 0.6 mol L(-1) NH(4)NO(3). Ni was found to be present in the chromatographic fraction in which quinic acid was identified by Q-TOF in all the tea infusions analysed, which had pH values between 5.6 and 6.0. The only exception was the infusion of hibiscus tea with a pH of 2.7, where results of speciation analysis showed that Ni is present in its divalent ionic form. PMID:23232960

  18. 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

  19. 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. PMID:24954648

  20. Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

    NASA Astrophysics Data System (ADS)

    Ohmi, Tatsuya; Mizuma, Kiminori; Matsuura, Kiyotaka; Iguchi, Manabu

    2008-02-01

    A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen.

  1. Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

    SciTech Connect

    Ohmi, Tatsuya; Matsuura, Kiyotaka; Iguchi, Manabu; Mizuma, Kiminori

    2008-02-15

    A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen.

  2. Porous NiTi shape memory alloys produced by SHS: microstructure and biocompatibility in comparison with Ti2Ni and TiNi3.

    PubMed

    Bassani, Paola; Panseri, Silvia; Ruffini, Andrea; Montesi, Monica; Ghetti, Martina; Zanotti, Claudio; Tampieri, Anna; Tuissi, Ausonio

    2014-10-01

    Shape memory alloys based on NiTi have found their main applications in manufacturing of new biomedical devices mainly in surgery tools, stents and orthopedics. Porous NiTi can exhibit an engineering elastic modulus comparable to that of cortical bone (12-17 GPa). This condition, combined with proper pore size, allows good osteointegration. Open cells porous NiTi was produced by self propagating high temperature synthesis (SHS), starting from Ni and Ti mixed powders. The main NiTi phase is formed during SHS together with other Ni-Ti compounds. The biocompatibility of such material was investigated by single culture experiment and ionic release on small specimen. In particular, NiTi and porous NiTi were evaluated together with elemental Ti and Ni reference metals and the two intermetallic TiNi3, Ti2Ni phases. This approach permitted to clearly identify the influence of secondary phases in porous NiTi materials and relation with Ni-ion release. The results indicated, apart the well-known high toxicity of Ni, also toxicity of TiNi3, whilst phases with higher Ti content showed high biocompatibility. A slightly reduced biocompatibility of porous NiTi was ascribed to combined effect of TiNi3 presence and topography that requires higher effort for the cells to adapt to the surface. PMID:24928669

  3. 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.

  4. HO-1 Protects against Hypoxia/Reoxygenation-Induced Mitochondrial Dysfunction in H9c2 Cardiomyocytes

    PubMed Central

    Chen, Dongling; Jin, Zhe; Zhang, Jingjing; Jiang, Linlin; Chen, Kai; He, Xianghu; Song, Yinwei; Ke, Jianjuan; Wang, Yanlin

    2016-01-01

    Background Mitochondrial dysfunction would ultimately lead to myocardial cell apoptosis and death during ischemia-reperfusion injuries. Autophagy could ameliorate mitochondrial dysfunction by autophagosome forming, which is a catabolic process to preserve the mitochondrial’s structural and functional integrity. HO-1 induction and expression are important protective mechanisms. This study in order to investigate the role of HO-1 during mitochondrial damage and its mechanism. Methods and Results The H9c2 cardiomyocyte cell line were incubated by hypoxic and then reoxygenated for the indicated time (2, 6, 12, 18, and 24 h). Cell viability was tested with CCK-8 kit. The expression of endogenous HO-1(RT-PCR and Western blot) increased with the duration of reoxygenation and reached maximum levels after 2 hours of H/R; thereafter, the expression gradually decreased to a stable level. Mitochondrial dysfunction (Flow cytometry quantified the ROS generation and JC-1 staining) and autophagy (The Confocal microscopy measured the autophagy. RFP-GFP-LC3 double-labeled adenovirus was used for testing.) were induced after 6 hours of H/R. Then, genetic engineering technology was employed to construct an Lv-HO1-H9c2 cell line. When HO-1 was overexpressed, the LC3II levels were significantly increased after reoxygenation, p62 protein expression was significantly decreased, the level of autophagy was unchanged, the mitochondrial membrane potential was significantly increased, and the mitochondrial ROS level was significantly decreased. Furthermore, when the HO-1 inhibitor ZnPP was applied the level of autophagy after reoxygenation was significantly inhibited, and no significant improvement in mitochondrial dysfunction was observed. Conclusions During myocardial hypoxia-reoxygenation injury, HO-1 overexpression induces autophagy to protect the stability of the mitochondrial membrane and reduce the amount of mitochondrial oxidation products, thereby exerting a protective effect. PMID

  5. 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. PMID:22421399

  6. Absolute VUV Photoionization Spectra for Hcho, HO{_2}, and H{_2}O{_2} from 10.5-12.0 eV

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    The absolute vacuum ultraviolet (VUV) photoionization spectra of formaldehyde (HCHO), the hydroperoxy radical (HO{_2}) and hydrogen peroxide (H{_2}O{_2}) have been measured. The ability to quantify these species is critical for photoionization mass spectrometry studies of the kinetics of atmospheric and combustion reactions, which require accurate cross sections over a wide range of ionization energies. Experiments were performed at the Advanced Light Source (ALS) synchrotron at the Lawrence Berkeley National Laboratory. HCHO, HO{_2}, and H{_2}O{_2} were generated from the oxidation of methanol which is initiated by pulsed-laser-photolysis of Cl{_2} in a low pressure flow cell. Sampled gas was ionized by tunable VUV radiation from the ALS synchrotron and detected by time-resolved multiplexed photoionization mass spectrometry using the Sandia Multiplexed Chemical Kinetics Reactor. The photoionization spectra were obtained by scanning the photon energy from 10.5 to 12.0 eV. Absolute cross sections were determined relative to methanol from measurements of the depletion of precursors and kinetic modeling of the initial chemistry ({<} 10 ms). The absolute photoionization spectrum of HCHO and the relative photoionization spectra of HO{_2} and H{_2}O{_2} are in good agreement with previous work. D. L. Osborn, P. Zou, H. Johnson, C. C. Hayden, C. A. Taatjes, V. D. Knyazev, S. W. North, D. S. Peterka, M. Ahmed, S. R. Leone. Rev. Sci. Inst. 2008, 79, 104103. G. Cooper, J. E. Anderson, C. E. Brion. Chem. Phys. 1996, 209, 61. M. Litorja, B. J. Ruscic. Electron Spectrosc. Relat. Phenom. 1998, 97, 131.

  7. Nonpoint sources

    SciTech Connect

    Selzer, L.

    1994-12-31

    Nonpoint source pollution remains the most pervasive water quality issue faced today. Unlike pollution from point sources, nonpoint source pollution is diffuse both in terms of its origin and the manner in which it enters ground and surface waters. It results from a great variety of human activities that take place over a wide geographic area perhaps many hundreds or even thousands of acres. And unlike pollutants from point sources--which enter the environment at well-defined locations and in relatively even, continuous discharges--pollutants from nonpoint sources usually find their way into surface and ground waters in sudden surges associated with rainfall, thunderstorms, or snowmelt. The author discusses some of the most significant sources of nonpoint source pollution.

  8. 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

  9. NiTinol performance characterization and rotary actuator design

    NASA Astrophysics Data System (ADS)

    Mabe, James H.; Ruggeri, Robert T.; Rosenzweig, Ed; Yu, Chin-Jye M.

    2004-07-01

    The successful and practical application of shape memory alloy (SMA) torque tube actuators has frequently been hindered by an incomplete understanding of the effects of manufacturing and processing variables, particularly when working with large-scale systems producing high force and large displacements. Recently the authors have developed data for NiTinol SMA torque tubes subjected to a variety of processes routinely encountered in everyday industrial practice, with the objective of developing a robust and reliable high-energy actuator. Data are presented for more than 25 NiTinol torque tubes 5.5" long by 0.4" in diameter. The tubes were tested over a range of steady and variable loads exceeding 150 in-lbs of torque, with angular displacements of more than 60 degrees, and for durations exceeding 10,000 thermal cycles. Each tube's performance is characterized as a function of material source, level of cold work, heat treatment, tube fabrication technique, and training regime, and the results are shown. Changes in mechanical and shape memory property were also tracked, and they are reported. Application of NiTinol characteristics to practical design and fabrication of SMA actuators meeting a wide range of angular displacement and torque requirements will also be discussed.

  10. Unique Sandwiched Carbon Sheets@Ni-Mn Nanoparticles for Enhanced Oxygen Evolution Reaction.

    PubMed

    Zhang, Yan; Zhang, Huijuan; Yang, Jiao; Bai, Yuanjuan; Qiu, Huajun; Wang, Yu

    2016-05-11

    A unique sandwich-like architecture, where Ni-Mn nanoparticles are enveloped in coupled carbon sheets (CS@Ni-Mn), has been successfully fabricated. In the synthesis process, a great quantity of uniform NiMnO3 nanosheets generated by a universal hydrothermal method acts as precursors and templates and the cheap, environmentally friendly and recyclable glucose functions as a green carbon source. Via subsequent hydrothermal reaction and thermal annealing, sandwiched nanocomposites with Ni-Mn nanoparticles embedded inside and carbon sheets encapsulating outside can be massively prepared. The novel sandwich-like CS@Ni-Mn possesses numerous advantages, such as an intrinsic porous feature, large specific surface area, and enhanced electronic conductivity. Moreover, as a promising NiMn-based oxygen evolution reaction (OER) catalyst, the special sandwiched nanostructure demonstrates improved electrochemical properties in 1 M KOH, including a low overpotential of about 250 mV, a modest Tafel slope of 40 mV dec(-1), excellent stability over 2000 cycles, and durability for 40 h. PMID:27101350

  11. Study of the preparation of NI-Mn-Zn ferrite using spent NI-MH and alkaline Zn-Mn batteries

    NASA Astrophysics Data System (ADS)

    Xi, Guoxi; Xi, Yuebin; Xu, Huidao; Wang, Lu

    2016-01-01

    Magnetic nanoparticles of Ni-Mn-Zn ferrite have been prepared by a sol-gel method making use of spent Ni-MH and Zn-Mn batteries as source materials. Characterization by X-ray diffraction was carried out to study the particle size. The presence of functional groups was identified by Fourier transform infrared spectroscopy. From studies by thermogravimetry and differential scanning calorimetry, crystallization occurred at temperatures above 560 °C. The magnetic properties of the final products were found to be directly influenced by the average particle size of the product. The Ms values increase and the Hc values decrease as the size of the Ni-Mn-Zn ferrite particles increases.

  12. 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

  13. Cyclic and isothermal oxidation behavior at 1100 and 1200 C of Ni-20Cr, Ni-20Cr-3Mn, Ni-20Cr-3Si, and Ni-40Cr alloys

    NASA Technical Reports Server (NTRS)

    Lowell, C. E.

    1973-01-01

    Alloys of Ni-20Cr, Ni-20Cr-3Mn, Ni-20Cr-3Si, and Ni-40Cr were cyclically oxidized at 1100 and 1200 C for up to 100 hours. Oxidation behavior was judged by sample thickness and weight change, metallography, diffraction, and microprobe analysis. The least attacked were Ni-40Cr and Ni-20Cr-3Si. The alloy Ni-20Cr-3Mn was much less attacked than Ni-20Cr, but more than the other alloys. The formation of Cr2O3 accounted for the increased resistance of Ni-Cr and Ni-20Cr-3Si, and the formation of MnCr2O4 accounts for the improvement in Ni-20Cr-3mn over Ni-20Cr.

  14. New rare earth metal-rich indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu)—synthesis and crystal chemistry

    NASA Astrophysics Data System (ADS)

    Lukachuk, Mar'yana; Galadzhun, Yaroslav V.; Zaremba, Roman I.; Dzevenko, Mariya V.; Kalychak, Yaroslav M.; Zaremba, Vasyl I.; Rodewald, Ute Ch.; Pöttgen, Rainer

    2005-09-01

    The rare earth-nickel-indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14Co 2In 3 type, P4 2/ nmc, Z=4, a=888.1(1), c=2134.7(4), wR2=0.0653, 1381 F2 values, 63 variables for Sc 13.89Ni 3.66In 2.45; a=961.2(1), c=2316.2(5), wR2=0.0633, 1741 F2 values, 64 variables for Y 13.84Ni 3.19In 2.97; a=965.3(1), c=2330.5(5), wR2=0.0620, 1765 F2 values, 63 variables for Gd 14Ni 3.29In 2.71; a=956.8(1), c=2298.4(5), wR2=0.0829, 1707 F2 values, 64 variables for Tb 13.82Ni 3.36In 2.82; a=951.7(1), c=2289.0(5), wR2=0.0838, 1794 F2 values, 64 variables for Dy 13.60Ni 3.34In 3.06; a=948.53(7), c=2270.6(1), wR2=0.1137, 1191 F2 values, 64 variables for Ho 13.35Ni 3.17In 3.48; a=943.5(1), c=2269.1(5), wR2=0.0552, 1646 F2 values, 64 variables for Er 13.53Ni 3.14In 3.33; a=938.42(7), c=2250.8(1), wR2=0.1051, 1611 F2 values, 64 variables for Tm 13.47Ni 3.28In 3.25; a=937.3(1), c=2249.6(5), wR2=0.0692, 1604 F2 values, 64 variables for Tm 13.80Ni 3.49In 2.71; and a=933.4(1), c=2263.0(5), wR2=0.0709, 1603 F2 values, 64 variables for Lu 13.94Ni 3.07In 2.99. The RE14Ni 3In 3 indides show significant Ni/In mixing on the 4 c In1 site. Except the gadolinium compound, the RE14Ni 3In 3 intermetallics also reveal RE/In mixing on the 4 c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE14Ni 3In 3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell at an In2-In2 distance of 304 pm (for Gd 14Ni 3.29In 2.71). The crystal chemical peculiarities of the RE14Ni 3In 3 indides are briefly discussed.

  15. Fe, Ni and Zn speciation, in airborne particulate matter

    NASA Astrophysics Data System (ADS)

    Thiodjio Sendja, Bridinette; Aquilanti, Giuliana; Vassura, Ivano; Giorgetti, Marco

    2016-05-01

    The study of elemental speciation in atmospheric particulate matter is important for the assessment of the source of the particle as well for the evaluation of its toxicity. XANES data at Fe, Ni, and Zn K-edges are recorded on a sample of urban dust (from the Rimini area of Emilia Romagna region, Italy) deposited on a filter and on the NIST standard reference material 1648. Using linear combination fitting we give an indication of the chemical species of the three metals present in the samples.

  16. Reliability and Validity of the HoNOS-LD and HoNOS in a Sample of Individuals with Mild to Borderline Intellectual Disability and Severe Emotional and Behavior Disorders

    ERIC Educational Resources Information Center

    Tenneij, Nienke; Didden, Robert; Veltkamp, Eline; Koot, Hans M.

    2009-01-01

    In this study, psychometric properties of the Health of the Nation Outcome scales (HoNOS) and Health of the Nation Outcome Scales for People with Learning Disabilities (HoNOS-LD) were investigated in a sample (n = 79) of (young) adults with mild to borderline intellectual disability (ID) and severe behavior and mental health problems who were…

  17. 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. PMID:26928589

  18. Who is El Niño?

    NASA Astrophysics Data System (ADS)

    Philander, S. George

    It is a curious story, about a phenomenon we first welcomed as a blessing but now view with dismay, if not horror [Philander, 1998]. We named it El Niño for the child Jesus, provided it with relatives—La Niña and ENSO—and are devoting innumerable studies to the description and idealization of this family. These scriptures provide such a broad spectrum of historical, cultural, and scientific perspectives that there is now confusion about the identity of El Niño. Trenberth [1997] summarizes the situation as follows.The atmospheric component tied to El Niño is termed the “Southern Oscillation.” Scientists often call the phenomenon where the atmosphere and ocean collaborate ENSO, short for El Niño-Southern Oscillation. El Niño then corresponds to the warm phase of ENSO. The opposite “La Niña” (“the girl” in Spanish) phase consists of a basinwide cooling of the tropical Pacific and thus the cold phase of ENSO. However, for the public, the term for the whole phenomenon is “El Niño.”

  19. AF Ni-Cd cell qualification program

    NASA Technical Reports Server (NTRS)

    Hall, Steve; Brown, Harry; Collins, G.; Hwang, Warren

    1994-01-01

    The present status of the USAF NiCd cell qualification program, which is underway at the Naval Surface Warfare Center-Crane Division, is summarized. The following topics are discussed: overview; background; purpose; stress tests; results for super Ni-Cd; results for SAFT cells; GPS stress test; GPS simulated orbit; and results for gates cells. The discussion is presented in viewgraph format.

  20. Ion scattering experiment on Ni(110) surface

    SciTech Connect

    Nicholas, B.; Rambabu, B.; Collins, W.E.

    1986-01-01

    Light emission from excited neutral scattered Ne and sputtered Ni were investigated using the LEIS method. A 5-keV Ne/sup +/ beam was used to bombard a Ni(110) surface. Results of the light emission data is presented and compared with neutral production of Ne. 4 refs., 3 figs.

  1. Comparative geochemistry of four ferromanganese crusts from the Pacific Ocean and significance for the use of Ni isotopes as paleoceanographic tracers

    NASA Astrophysics Data System (ADS)

    Gueguen, Bleuenn; Rouxel, Olivier; Rouget, Marie-Laure; Bollinger, Claire; Ponzevera, Emmanuel; Germain, Yoan; Fouquet, Yves

    2016-09-01

    Ferromanganese (Fe-Mn) crusts are potential archive of the Ni isotope composition of seawater through time. In this study we aim at (1) understanding Ni isotope fractionation mechanisms and metal enrichment processes in Fe-Mn deposits, (2) addressing global vs. local control of Ni isotope composition of these deposits. Two Fe-Mn crusts from the North Pacific Ocean (Apuupuu Seamount, Hawaii) and two Fe-Mn crusts from the South Pacific Ocean (near Rurutu Island, Austral archipelago of French Polynesia) were characterized for their elemental geochemistry and Ni isotope composition. Geochemical analyses were performed at millimeter intervals in order to provide time-resolved record of Ni isotopes. Chronology and growth rates were determined using cosmogenic 10Be isotope abundances. The results show that, despite different growth rates, textures and geochemical patterns, Fe-Mn crusts from both North and South Pacific Oceans have fairly homogenous Ni isotope compositions over the last ∼17 Ma, yielding average δ60/58Ni values of 1.79 ± 0.21‰ (2sd, n = 31) and 1.73 ± 0.21‰ (2sd, n = 21) respectively. In one crust sample, however, layers directly in contact with the altered substrate show anomalously light δ60/58Ni values down to 0.25 ± 0.05‰ (2se) together with rejuvenated 10Be/9Be ratios correlating with elevated Ni/Mn ratios. Such patterns are best explained by protracted fluid-rock interactions leading to alteration of Mn-phases after crust formation. Isotopically light Ni would be the result of Ni isotope fractionation during adsorption rather than the contribution of external Ni sources (e.g. hydrothermal sources) having light Ni isotope compositions. The combination of our results with previously published data on Fe-Mn crusts indicates that the average Ni isotope composition in deep waters has not changed through the Cenozoic (∼70 Ma). We propose that Ni isotope variations in Fe-Mn crusts may not only record variations of Ni sources to the oceans, but

  2. Preparation and characterization of Ni-P/Ni3.1B composite alloy coatings

    NASA Astrophysics Data System (ADS)

    Wang, Yurong; He, Jiawei; Wang, Wenchang; Shi, Jianhua; Mitsuzaki, Naotoshi; Chen, Zhidong

    2014-02-01

    The preparation of Ni-P/Ni3.1B composite alloy coating on the surface of copper was achieved by co-deposition of Ni3.1B nanoparticles with Ni-P coating during electroless plating. Ni-P-B alloy coating was obtained by heat-treating the as-plated Ni-P/Ni3.1B composite coating. The effect of the concentration of sodium alginate, borax, thiourea, Ni3.1B, temperature, and pH value on the deposition rate and B content were investigated and determined to be: 30 g L-1, 10 g L-1, 2 mg L-1, 20 mg L-1, 70 °C and 9.0 , respectively. Sodium alginate and thiourea were played as surfactant for coating Ni3.1B nanoparticles and stabilizer for the plating bath, respectively. Ni-P/Ni3.1B composite coating had good performance such as corrosion resistance and solderability.

  3. Water dissociation on Ni(100) and Ni(111): Effect of surface temperature on reactivity

    SciTech Connect

    Seenivasan, H.; Tiwari, Ashwani K.

    2013-11-07

    Water adsorption and dissociation on Ni(100) and Ni(111) surfaces are studied using density functional theory calculations. Water adsorbs on top site on both the surfaces, while H and OH adsorb on four fold hollow and three fold hollow (fcc) sites on Ni(100) and Ni(111), respectively. Transition states (TS) on both surfaces are identified using climbing image-nudged elastic band method. It is found that the barrier to dissociation on Ni(100) surface is slightly lower than that on Ni(111) surface. Dissociation on both the surfaces is exothermic, while the exothermicity on Ni(100) is large. To study the effect of lattice motion on the energy barrier, TS calculations are performed for various values of Q (lattice atom coordinate along the surface normal) and the change in the barrier height and position is determined. Calculations show that the energy barrier to reaction decreases with increasing Q and increases with decreasing Q on both the surfaces. Dissociation probability values at different surface temperatures are computed using semi-classical approximation. Results show that the influence of surface temperature on dissociation probability on the Ni(100) is significantly larger compared to that of Ni(111). Moreover, on Ni(100), a dramatic shift in energy barrier to lower incident energy values is observed with increasing surface temperature, while the shift is smaller in the case of Ni(111)

  4. Organics Substantially Reduce HO2 Uptake onto Aerosols Containing Transition Metal ions.

    PubMed

    Lakey, Pascale S J; George, Ingrid J; Baeza-Romero, Maria T; Whalley, Lisa K; Heard, Dwayne E

    2016-03-10

    A HO2 mass accommodation coefficient of α = 0.23 ± 0.07 was measured onto submicron copper(II)-doped ammonium sulfate aerosols at a relative humidity of 60 ± 3%, at 293 ± 2 K and at an initial HO2 concentration of ∼ 1 × 10(9) molecules cm(-3) by using an aerosol flow tube coupled to a sensitive fluorescence assay by gas expansion (FAGE) HO2 detection system. The effect upon the HO2 uptake coefficient γ of adding different organic species (malonic acid, citric acid, 1,2-diaminoethane, tartronic acid, ethylenediaminetetraacetic acid (EDTA), and oxalic acid) into the copper(II)-doped aerosols was investigated. The HO2 uptake coefficient decreased steadily from the mass accommodation value to γ = 0.008 ± 0.009 when EDTA was added in a one-to-one molar ratio with the copper(II) ions, and to γ = 0.003 ± 0.004 when oxalic acid was added into the aerosol in a ten-to-one molar ratio with the copper(II). EDTA binds strongly to copper(II) ions, potentially making them unavailable for catalytic destruction of HO2, and could also be acting as a surfactant or changing the viscosity of the aerosol. The addition of oxalic acid to the aerosol potentially forms low-volatility copper-oxalate complexes that reduce the uptake of HO2 either by changing the viscosity of the aerosol or by causing precipitation out of the aerosol forming a coating. It is likely that there is a high enough oxalate to copper(II) ion ratio in many types of atmospheric aerosols to decrease the HO2 uptake coefficient. No observable change in the HO2 uptake coefficient was measured when the other organic species (malonic acid, citric acid, 1,2-diaminoethane, and tartronic acid) were added in a ten-to-one molar ratio with the copper(II) ions. PMID:26484935

  5. 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

  6. Simultaneous Quantification of OH and HO_2 in Dimethyl Ether Oxidation Using Faraday Rotation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Brumfield, Brian; Yang, Xueliang; Lefkowitz, Joseph; Ju, Yiguang; Wysocki, Gerard

    2014-06-01

    OH and HO_2 are key radical species that control the autoignition and flame chemistry of fuels. Quantification of these radicals in the low-temperature oxidation of fuels is challenging due to their low concentrations. Strong spectral interference from more abundant non-radical species can further complicate accurate quantification of OH and HO_2. Faraday Rotation Spectroscopy (FRS), a laser-based diagnostic that exploits magneto-optical properties of paramagnetic radical species, can overcome these technical challenges to provide sensitive and selective in situ quantification of radicals. Previously we have been able to illustrate the strengths of FRS in quantification of HO_2 radicals in the low-temperature oxidation of dimethyl ether. Recently we have constructed a dual-wavelength FRS system capable of simultaneous in situ measurement of OH and HO_2. A DFB diode laser operating at 2.8 μm is used to target the Q(1.5e) and Q(1.5f) transitions in the fundamental vibrational band of the 2Π3/2 ground electronic state of OH. An EC-QCL operating at 7.1 μm is used to target a Q-branch spectral feature in the νb{2} vibrational band of HO_2. Concentrations of the target species are extracted from the measured spectra through fitting of an FRS spectral model. Based on preliminary retrievals, 3σ detection limits of <1 ppmv for OH and HO_2 have been estimated from the non-linear least-squares fitting results. In this talk I will discuss the application of dual-wavelength FRS for sensitive measurement of OH and HO_2 radicals generated by oxidation of dimethyl ether in a flow reactor over a 520 K - 1050 K temperature range. B. Brumfield et al., J. Phys. Chem. Lett., 4, 872 (2013) B. Brumfield et al., ``Dual Modulation Faraday Rotation Spectroscopy of HO_2 in a Flow Reactor'' Accepted in Optics Letters (2014) N. Kurimoto et al., ``Quantitative Measurements of HO_2 / H_2O_2 and Intermediate Species in Low and Intermediate Temperature Oxidation of Dimethyl Ether'', Submitted

  7. The Pacific Northwest Hydrological Observatory (PNW HO): Hypothesis and model testing power through diversity

    NASA Astrophysics Data System (ADS)

    McDonnell, J. J.; Grant, G.; Hulse, D.

    2004-12-01

    The Pacific Northwest Hydrological Observatory (PNW HO) is a proposed national facility for the examination of the linkages between hydrologic and biogeochemical cycles, sustainability of water resources in the face of increasing human demands and climate change, hydrologic and ecosystem interactions, and hydrologic extremes. The PNW HO infrastructure will support research that examines forcings, feedbacks and couplings across hydro-eco-climatic interfaces, process scaling, and development of new predictive schemes and methods to reduce predictive uncertainty. Much of the data collection infrastructure is already in place, in the form of USGS gauging, local and State data recording. The PNW HO includes a novel experimental design that twins two neighboring watersheds-the humid Willamette and arid Deschutes River Basins-that represent a full range of landscape gradients and societal problems relating to water quantity and quality. Workers at the PNW HO will be able to build upon existing synthesis documents in the form of the Willamette River Basin Planning Atlas and recent AGU Monograph on the Deschutes River Basin. The PNW HO design builds upon the HJ Andrews LTER site in the headwaters and recent listing of the Willamette River Basin as a UNESCO HELP international observatory. The PNW HO has access to one of the richest SNOTEL datasets in North America along the divide between the Willamette and Deschutes Basins. The Willamette is a USGS NAWQA basin and the Deschutes has been the focus of a major USGS groundwater investigation, and is one of five sites nationally in the Fire Learning Network. Finally, and perhaps most importantly for technology transfer of HO science to policy and practice, the PNW HO enjoys a rather unique combination of Oregon's state-based land use planning and doctrine of prior appropriations water law (land use planning and water rights). While there are certainly areas in the West where human populations are growing as fast or faster, none

  8. Electrochemical properties of NiO-Ni nanocomposite as anode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, X. H.; Tu, J. P.; Zhang, B.; Zhang, C. Q.; Li, Y.; Yuan, Y. F.; Wu, H. M.

    NiO-Ni nanocomposite was prepared by calcining a mixture of Ni 2(OH) 2CO 3 and ethanol in a tube furnace at 700 °C for 45 min in air. The microstructure and morphology of the powders were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). In the composite, nanoscale Ni particles (<10 nm) were dispersed in the NiO matrix (about 100 nm). Electrochemical tests showed that the nanocomposite had higher initial and reversible capacity than pure NiO. The presence of the nanoscale Ni phase had improved both of the initial coulombic efficiency and the cycling performance, due to its catalytic activity, which would facilitate the decomposition of Li 2O and the SEI during the charge process.

  9. A ternary Ni-Al-W EAM potential for Ni-based single crystal superalloys

    NASA Astrophysics Data System (ADS)

    Fan, Qin-Na; Wang, Chong-Yu; Yu, Tao; Du, Jun-Ping

    2015-01-01

    Based on experiments and first-principles calculations, a ternary Ni-Al-W embedded-atom-method (EAM) potential is constructed for the Ni-based single crystal superalloys. The potential predicts that W atoms do not tend to form clusters in γ(Ni), which is consistent with experiments. The impurity diffusion of W in γ(Ni) is investigated using the five-frequency model. The diffusion coefficients and the diffusion activation energy of W are in reasonable agreement with the data in literatures. By W doping, the lattice misfit between the two phases decreases and the elastic constants of γ‧(Ni3Al) increase. As for alloyed elements Co, Re and W, the pinning effect of solute atom on the γ(Ni)/γ‧(Ni3Al) misfit dislocation increases with the increasing of the atomic radius.

  10. Direct observation of infinite NiO2 planes in LaNiO2 films

    NASA Astrophysics Data System (ADS)

    Ikeda, Ai; Krockenberger, Yoshiharu; Irie, Hiroshi; Naito, Michio; Yamamoto, Hideki

    2016-06-01

    Epitaxial thin films of LaNiO2, which is an oxygen-deficient perovskite with “infinite layers” of Ni1+O2, were prepared by a low-temperature reduction of LaNiO3 single-crystal films on NdGaO3 substrates. We report the high-angle annular dark-field and bright-field scanning transmission electron microscopy observations of infinite NiO2 planes of c-axis-oriented LaNiO2 epitaxial thin films with a layer stacking sequence of NiO2/La/NiO2. Resistivity measurements on the films show T 2 dependence between 400 and 150 K and a negative Hall coefficient.

  11. Predictability of the Ningaloo Niño/Niña.

    PubMed

    Doi, Takeshi; Behera, Swadhin K; Yamagata, Toshio

    2013-01-01

    The seasonal prediction of the coastal oceanic warm event off West Australia, recently named the Ningaloo Niño, is explored by use of a state-of-the-art ocean-atmosphere coupled general circulation model. The Ningaloo Niño/Niña, which generally matures in austral summer, is found to be predictable two seasons ahead. In particular, the unprecedented extreme warm event in February 2011 was successfully predicted 9 months in advance. The successful prediction of the Ningaloo Niño is mainly due to the high prediction skill of La Niña in the Pacific. However, the model deficiency to underestimate its early evolution and peak amplitude needs to be improved. Since the Ningaloo Niño/Niña has potential impacts on regional societies and industries through extreme events, the present success of its prediction may encourage development of its early warning system. PMID:24100593

  12. Nanoscale structural heterogeneity in Ni-rich half-Heusler TiNiSn

    SciTech Connect

    Douglas, Jason E. Pollock, Tresa M.; Chater, Philip A.; Brown, Craig M.; Seshadri, Ram

    2014-10-28

    The structural implications of excess Ni in the TiNiSn half-Heusler compound are examined through a combination of synchrotron x-ray and neutron scattering studies, in conjunction with first principles density functional theory calculations on supercells. Despite the phase diagram suggesting that TiNiSn is a line compound with no solid solution, for small x in TiNi{sub 1+x}Sn there is indeed an appearance—from careful analysis of the scattering—of some solubility, with the excess Ni occupying the interstitial tetrahedral site in the half-Heusler structure. The analysis performed here would point to the excess Ni not being statistically distributed, but rather occurring as coherent nanoclusters. First principles calculations of energetics, carried out using supercells, support a scenario of Ni interstitials clustering, rather than a statistical distribution.

  13. Capture of Hydrogen Using ZrNi

    NASA Technical Reports Server (NTRS)

    Patton, Lisa; Wales, Joshua; Lynch, David; Parrish, Clyde

    2005-01-01

    Water, as ice, is thought to reside in craters at the lunar poles along with CH4 and H2 . A proposed robotic mission for 2012 will utilize metal/metal hydrides for H2 recovery. Specifications are 99% capture of H2 initially at 5 bar and 100C (or greater), and degassing completely at 300C. Of 47-systems examined using the van't Hoff equation, 4 systems, Mg/MgH2, Mg2Ni/Mg2NiH4, ZrNi/ZrNiH2.8, and Pd/PdH0.77, were considered likely candidates for further examination. It is essential, when selecting a system, to also examine questions regarding activation, kinetics, cyclic stability, and gas impurity effects. After considering those issues, ZrN1 was selected as the most promising candidate, as it is easily activated and rapidly forms ZrNiH 2.8 . In addition, it resists oxide poisoning by CO2, and H2O, while some oxidation by O2 is recommended for improved activation . The presence of hydrogen in the as received Zr-Ni alloy from Alfa Aesar posed additional technical problems. X-ray diffraction of the Zr-Ni powder (-325 mesh), with a Zr:Ni wt% ratio of 70:30, was found to consist of ZrH2, ZrNiH2.8, and ZrNi. ZrH2 in the alloy presented the risk that after degassing that both Zr and ZrNi would be present, and thus lead to erroneous results regarding the reactivity of ZrNi with H2 . Fortunately, ZrH2 is a highly stable hydride that does not degas H2 to any significant extent at temperatures below 300C. Based on equilibrium calculations for the decomposition of ZrH2, only 1 millionth of the hydride decomposed at 300C under a N2 atmosphere flowing at 25 ccm for 64 hours, the longest time for pretreatment employed in the investigation. It was possible, from the X-ray results and knowledge of the Zr:Ni ratio, to compute the composition of a pretreated specimen as being 76 wt% ZrNi and the balance ZrH2.

  14. NiAl alloys for structural uses

    NASA Technical Reports Server (NTRS)

    Koss, D. A.

    1991-01-01

    Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the

  15. Neutron Spectroscopic factors of 56Ni

    NASA Astrophysics Data System (ADS)

    Sanetullaev, A.; Ghosh, T. K.; Lynch, W. G.; Bazin, D.; Chajecki, Z.; Coupland, Daniel; Hodges, R.; Lee, Jenny; Henzl, V.; Henzlova, D.; Rogers, A. M.; Sun, Z. Y.; Tsang, M. B.; Winkelbauer, J.; Youngs, M.; Famiano, M.; Clement, R. R. C.; Howard, M. E.; Cizewski, J. A.; O'Malley, P. D.; Manning, B.; Charity, R. J.; Charity, L. G.; Shapira, D.; Shmitt, K. T.

    2011-10-01

    The exact shell-structure of the unstable doubly-magic nucleus 56Ni has attracted a lot of interest recently. To test if 56Ni is a good core, 56Ni(p, d)55Ni transfer reactions were measured using 56Ni beam at two different energies, 37 MeV/u and 80 MeV/u, in inverse kinematics in two experiments. The second measurement was done in order to test the sensitivity of reaction cross sections and models to reaction energies. The measurements were performed at NSCL using HiRA array and S800 spectrometer. Spectroscopic factors have been extracted for the first experiment. The results show good agreement with shell-model calculations. Preliminary results of the measurements with 80 MeV/u beam will be presented as well. This work is funded by NSF under Grant No. PHY-0606007.

  16. Tensile deformation of NiTi wires.

    PubMed

    Gall, Ken; Tyber, Jeff; Brice, Valerie; Frick, Carl P; Maier, Hans J; Morgan, Neil

    2005-12-15

    We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed. PMID:16138359

  17. Charge ordering in Ni1 +/Ni2 + nickelates: La4Ni3O8 and La3Ni2O6

    NASA Astrophysics Data System (ADS)

    Botana, Antia S.; Pardo, Victor; Pickett, Warren E.; Norman, Michael R.

    2016-08-01

    Ab initio calculations allow us to establish a close connection between the Ruddlesden-Popper layered nickelates and cuprates not only in terms of filling of d levels (close to d9) but also because they show Ni1 +(S =1 /2 ) /Ni2 +(S =0 ) stripe ordering. The insulating charge-ordered ground state is obtained from a combination of structural distortions and magnetic order. The Ni2 + ions are in a low-spin configuration (S =0 ) yielding an antiferromagnetic arrangement of Ni1 + S =1 /2 ions like the long-sought spin-1/2 antiferromagnetic insulator analog of the cuprate parent materials. The analogy extends further with the main contribution to the bands near the Fermi energy coming from hybridized Ni dx2-y2 and O p states.

  18. XAFS study of Ni (II) aminovinylketone complexes

    NASA Astrophysics Data System (ADS)

    Yalovega, Galina E.; Vlasenko, Valerii G.; Uraev, Ali I.; Garnovskii, Alexander D.; Soldatov, Alexander V.

    2006-11-01

    The functional properties of the active sites in a metalloproteins depend on coordination geometry of metal, the number and the nature of coordination ligands. The Ni K-edge XAFS spectra of novel nickel complexes as models for the MeN 2O 2(S 2) active site in metalloproteins were measured and analyzed. Theoretical analysis of the Ni K-edge XANES was performed using FDMNES code based on the finite difference method (FDM) to solve the Schrödinger equation beyond muffin-tin approximations and self-consistent full multiple-scattering approach (code FEFF8.2). It was found that the spectrum is almost totally formed by the octahedron of the nearest neighbor atoms around Ni ion in the II (Ni) complex. The III (Ni) complex active center exists in square-planar configuration with shorter distances.

  19. 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. PMID:24978777

  20. Growth and spectroscopic properties of the 2.9 μm Tm,Ho:LuYAG laser crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Huili; Sun, Dunlu; Luo, Jianqiao; Fang, Zhongqing; Zhao, Xuyao; Cheng, Maojie; Zhang, Qingli; Yin, Shaotang

    2015-09-01

    Lu2.4Y0.6Al5O12 (LuYAG) crystals with three different doping concentrations of Tm3+ and Ho3+ were grown successfully by the Czochralski method. The crystals exhibit broad absorption band at 783 nm and the full width at half maximum (FWHM) are about 11 nm. Excited by 783 nm laser diode (LD), strong fluorescence peaks are observed near 2.9 μm, suggesting that the Tm3+ ions can act as the sensitizer for Ho3+ ions. The stimulated emission cross-sections at 2.911 μm are calculated to be 5.49 × 10-18 cm2, 3.11 × 10-18 cm2, and 4.04 × 10-18 cm2, respectively. Compared with the Tm,Ho:LuAG, and Tm,Ho:YAG crystals, the Tm,Ho:LuYAG crystal with 3 at.% Tm3+ and 1 at.% Ho3+ has a relatively longer lifetime 0.138 ms for the upper level 5I6 and a shorter lifetime 7.25 ms for the lower level 5I7, which is advantageous to the population inversion. These results indicate that the Tm,Ho:LuYAG crystal with 3 at.% Tm3+ and 1 at.% Ho3+ is a new potential candidate for realizing the 2.911 μm laser output.

  1. 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.

  2. 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...

  3. Protein assay for heme oxygenase-1 (HO-1) induced by chemicals in HepG2 cells.

    PubMed

    Miyamoto, Yohei; Ohshida, Keiyu; Sasago, Kaori

    2009-12-01

    Levels of heme oxygenase-1 (HO-1), a stress response protein, were measured to examine oxidative stress induced by several chemicals in HepG2 cells with and without S9mix using an ELISA. CdCl(2), heme, and diclofenac sodium salt (diclofenac) were used as inducers of HO-1. Acetaminophen (AAP) and cyclophosphamide (CP) were used as oxidative stress inducers. Stannic mesoporphyrin (SnMP) was used as an inhibitor of HO activity. Cytotoxicity was determined, and HO-1 levels were measured in HepG2 cells exposed to chemicals other than CP with non-metabolic activation without S9mix, and to diclofenac, AAP and CP with metabolic activation with S9mix. HO-1 levels were increased by CdCl(2) (7.5 microM), heme (10, 100 microM), and stannic mesoporphyrin (SnMP) (10 microM), but were not changed by AAP, and were decreased by diclofenac. HO-1 levels were increased by diclofenac (300 microM), and CP (36 microM), but were unaffected by AAP because of low sensitivity in HepG2 cells. The induction of HO-1 expression was first observed in cultured HepG2 cells treated with CP under conditions involving metabolic activation. These results showed the measurement of HO-1 protein levels in this system is useful when assessing oxidative stress as a tool for detecting drug toxicity. PMID:19952508

  4. Identification and molecular characterization of novel and divergent HoBi-like pestiviruses from naturally infected cattle in India.

    PubMed

    Mishra, N; Rajukumar, K; Pateriya, A; Kumar, M; Dubey, P; Behera, S P; Verma, A; Bhardwaj, P; Kulkarni, D D; Vijaykrishna, D; Reddy, N D

    2014-11-01

    HoBi-like pestiviruses have been sporadically reported from naturally infected cattle in South America, Asia and Europe. While the closely related bovine viral diarrhoea virus 1 (BVDV-1) and BVDV-2 have been reported from cattle in India, the prevalence and diversity of HoBi-like viruses have not yet been studied. Here we report the genetic diversity and molecular characteristics of HoBi-like viruses, through systematic surveillance in cattle (n=1049) from 21 dairy farms across India during 2012-2013. On the basis of real-time RT-PCR, virus isolation and nucleotide sequencing results, of the 20 pestivirus positive cattle, HoBi-like viruses were identified in 19 cattle from four farms in three states and BVDV-1b in one cattle. Phylogenetic analysis of 5'-UTR and N(pro) region identified the circulation of two lineages of HoBi-like viruses in India, that were distinct to those circulating globally, highlighting the independent evolution of at least three lineages of HoBi-like viruses globally. Antigenic differences were also evident between the two Indian lineages. In addition to revealing that HoBi-like virus may be more widespread in Indian cattle than previously reported, this study shows greater genetic divergence of HoBi-like viruses indicating a need for continued pestivirus surveillance in cattle. PMID:25301283

  5. 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.

  6. Mid-infrared emission characteristic and energy transfer of Ho3+-doped tellurite glass sensitized by Tm 3+.

    PubMed

    Chen, G X; Zhang, Q Y; Yang, G F; Jiang, Z H

    2007-05-01

    We report on 2.0-microm emission characteristic and energy transfer of Ho3+-doped tellurite glass sensitized by Tm3+ upon excitation of a conventional 808 nm laser diode. The Judd-Ofelt strength parameters, spontaneous radiative transition probabilities and radiative lifetime of Ho3+ have been calculated from the absorption spectra by using the Judd-Ofelt theory. Significant enhancement of 2.0-microm emission of Ho3+ has been observed with increasing Tm3+ doping up to 0.7 mol%. The energy transfer coefficient of the forward Tm3+-->Ho3+ is approximately 17 times larger than that of the backward Tm3+<--Ho3+ energy transfer. Our result indicates that the maximum gain of 2.0-microm emission, assigned to the transition of (5)I7-->(5)I8 of Ho3+, might be achieved from the tellurite glass at the concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. The high gain coefficient and quantum efficiency (1.16) along with the large value of the product of the stimulated emission cross-section and the measured radiative lifetime (4.12 x 10(-27) m(2)s) of the Ho3+/Tm3+-codoped tellurite glasses might find potential applications in efficient 2.0-microm laser. PMID:17393285

  7. 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…

  8. Magnetocaloric effect of the ternary Dy, Ho and Er platinum gallides

    NASA Astrophysics Data System (ADS)

    França, E. L. T.; dos Santos, A. O.; Coelho, A. A.; da Silva, L. M.

    2016-03-01

    Magnetic and magnetocaloric properties of equiatomic ternary gallides RPtGa (R=Dy, Ho and Er) compounds have been reported. All these compounds are iso-structural and order antiferromagnetically below 20 K. External applied magnetic field induces metamagnetic transition from antiferromagnetic to ferromagnetic state. Adiabatic entropy change (-ΔSM) shows negative contribution for magnetic field changes up to 10 kOe (for R=Ho and Er) and 30 kOe (for R=Dy) due to disordering of antiparallel spins with the external applied field. As the field change increases, only a positive asymmetric peak is observed. A broad -ΔSM peak is observed for HoPtGa, evidencing characteristics of a table-like behavior. HoPtGa and ErPtGa present the largest magnetocaloric effect (EMC) compared with DyPtGa, indicating that the nature of metamagnetic transition affects the magnetocaloric properties. The maximum value of adiabatic temperature change (∆ Tadmax) obtained for R=Dy, Ho and Er was respectively 4.1 K, 4.9 K and 6.7 K for ΔH=50 kOe. These values are comparable with the respective ∆ Tadmax reported for other RTX compounds in the same range of temperature and suggest that RPtGa compounds are attractive candidates for magnetic refrigeration in low temperature range (<20 K) with the advantage of not presenting hysteresis loss.

  9. High-pressure phase transition of MH3 (M: Er, Ho)

    NASA Astrophysics Data System (ADS)

    Hou, Pugeng; Tian, Fubo; Li, Da; Chu, Binhua; Zhao, Zhonglong; Liu, Bingbing; Cui, Tian

    2014-08-01

    Motivated by the potential high temperature superconductivity in hydrogen-rich materials, high-pressure structures of ErH3 and HoH3 were studied by using genetic algorithm method. Our calculations indicate that both ErH3 and HoH3 transform from P-3c1 structure to a monoclinic C2/m structure at about 15 GPa, and then transforms into a cubic Fm-3m structure at about 40 GPa. ErH3 and HoH3 adopt the same P63/mmc structure with space group P63/mmc at above about 220 and 196 GPa, respectively. For ErH3, the P63/mmc phase is stable up to at least 300 GPa, while for HoH3, a phase transformation P63/mmc → Cmcm occurs at about 216 GPa, and the Cmcm phase is stable up to at least 300 GPa. The P-3c1 ErH3 and HoH3 are calculated to demonstrate non-metallic character, and the other phases are all metallic phases.

  10. Magnetic structures in the magnetic phase diagram of Ho2RhIn8

    NASA Astrophysics Data System (ADS)

    Čermák, Petr; Prokeš, Karel; Ouladdiaf, Bachir; Boehm, Martin; Kratochvílová, Marie; Javorský, Pavel

    2015-04-01

    The magnetic phase diagram of the tetragonal Ho2RhIn8 compound has similar features to many related systems, revealing a zero magnetic field AF1 and a field-induced AF2 phases. Details of the magnetic order in the AF2 phase were not reported yet for any of the related compounds. In addition, only the Ho2RhIn8 phase diagram contains a small region of the incommensurate zero-field AF3 phase. We have performed a number of neutron diffraction experiments on single crystals of Ho2RhIn8 using several diffractometers including experiments in both horizontal and vertical magnetic fields up to 4 T. We present details of the magnetic structures in all magnetic phases of the rich phase diagram of Ho2RhIn8 . The Ho magnetic moments point along the tetragonal c axis in every phase. The ground-state AF1 phase is characterized by propagation vector k =(1 /2 ,0 ,0 ) . The more complex ferrimagnetic AF2 phase is described by four propagation vectors k0=(0 ,0 ,0 ) ,k1=(1 /2 ,0 ,0 ) ,k2=(0 ,1 /2 ,1 /2 ) ,k3=(1 /2 ,1 /2 ,1 /2 ) . The magnetic structure in the AF3 phase is incommensurate with kA F 3=(0.5 ,δ ,0 ) . Our results are consistent with theoretical calculations based on crystal field theory.

  11. Spectroscopic measurement of HO2, H2O2, and OH in the stratosphere

    NASA Technical Reports Server (NTRS)

    Park, J. H.; Carli, B.

    1991-01-01

    Stratospheric concentrations of HO2, H2O2, and OH have been retrieved simultaneously from the far-infrared emission spectra obtained with a balloon-borne Fourier transform spectrometer in June 1983 at 32 deg N latitude. Retrieved concentrations of HO2 and H2O2 are reported, along with vertical distributions of OH which were reported in an earlier paper for the afternoon, sunset, and nighttime periods for altitudes from 26 to 38 km. HO2 distributions are obtained with uncertainties that are about the same as OH for the same vertical range and for the afternoon and sunset periods. H2O2 concentration is obtained at an altitude of 30 km for the period that covers afternoon and sunset hours. The retrieved concentrations of these HO(x) species agree well with other individually measured results and the steady state photochemical predictions. The ratio HO2/OH at around 32 km seems to increase from the afternoon period to the sunset period.

  12. 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.

  13. 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.

  14. 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. PMID:27478131

  15. Toxicity of hydroxylated polychlorinated biphenyls (HO-PCBs) using the bioluminescent assay Microtox(®).

    PubMed

    Bhalla, Renu; Tehrani, Rouzbeh; Van Aken, Benoit

    2016-09-01

    Hydroxylated polychlorinated biphenyls (HO-PCBs) are toxic contaminants which are produced in the environment by biological or abiotic oxidation of PCBs. The toxicity of a suite of 23 mono-hydroxylated derivatives of PCBs and 12 parent PCBs was determined using the bacterial bioluminescent assay Microtox(®). All HO-PCBs tested exhibited higher toxicity than the corresponding parent PCB, with effect concentration 50 % (EC50) ranging from 0.07 to 133 mg L(-1). The highest toxicities were recorded with 4-hydroxylated derivatives of di-chlorinated biphenyls (EC50 = 0.07-0.36 mg L(-1)) and 2-hydroxylated derivatives of tri-chlorinated biphenyls carrying a chlorine substituent on the phenolic ring (EC50 = 0.34-0.48 mg L(-1)). The toxicity of HO-PCBs generally decreased when the degree of chlorination increased. Consistently with this observation, a significant positive correlation was measured between toxicity (measured by EC50) and octanol-water partition coefficient (pK ow) for the HO-PCBs under study (Pearson's correlation coefficient, r = 0.74), which may be explained by the lower solubility and bioavailability generally associated with higher hydrophobicity. This study is the first one which assessed the toxicity of a suite of PCBs and HO-PCBs using the bioluminescent assay Microtox(®), showing an inverse correlation between toxicity and hydrophobicity. PMID:27411941

  16. Home Assessment of Person-Environment Interaction (HoPE): content validation process.

    PubMed

    Rousseau, Jacqueline; Potvin, Louise; Dutil, Élisabeth; Falta, Patricia

    2013-10-01

    The purpose of this paper is to present the content validation, including a pilot test, of the Home Assessment of the Person-Environment Interaction (HoPE). The HoPE fills a gap for evaluating issues related to home adaptation. Using qualitative methods, a two-phase study was conducted: an expert consultation and a pilot test. The expert consultation was conducted via focus groups with occupational therapists (n = 20), and individual interviews with adults who had undergone home adaptation (n = 5). The pilot test was undertaken using a multiple case study design of four adults awaiting home adaptation. Data were audio-recorded, transcribed, and analyzed using NUD.IST software. In phase 1, experts agreed with the content of HoPE and suggested minor changes. In phase 2, HoPE enabled occupational therapists to identify handicap-creating situations. After both phases, the final version of HoPE is more comprehensive than other current tools and addresses the complex experiences of clients with whom occupational therapists work which suggests a new approach for practice regarding home adaptation. PMID:24102587

  17. Role of HO/CO in the Control of Peripheral Circulation in Humans.

    PubMed

    Sacerdoti, David; Mania, Despina; Pesce, Paola; Gaiani, Silvia; Gatta, Angelo; Bolognesi, Massimo

    2012-01-01

    Experimental studies show that the heme oxygenase/carbon monoxide system (HO/CO) plays an important role in the homeostasis of circulation and in the pathophysiology of hypertension. No data are available on its role in the control of peripheral circulation in humans. We evaluated the effects of inhibition of HO with stannous mesoporphyrin IX (SnMP) (200 μM) locally administered by iontophoresis, on human skin blood flow, evaluated by laser-Doppler flowmetry, in the presence and absence of nitric oxide synthase (NOS) inhibition with L-NG-Nitroarginine methyl ester (L-NAME) (100 μM). We also evaluated the effect of HO inhibition on vasodilatation induced by acetylcholine (ACh) and vasoconstriction caused by noradrenaline (NA). SnMP and L-NAME caused a similar 20-25% decrease in skin flow. After nitric oxide (NO) inhibition with L-NAME, HO inhibition with SnMP caused a further 20% decrease in skin perfusion. SnMP decreased vasodilatation induced by ACh by about 70%, while it did not affect vasoconstriction to NA. In conclusion, HO/CO participates in the control of peripheral circulation, independently from NO, and is involved in vasodilatation to ACh. PMID:22500215

  18. 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

  19. Transurethral holmium laser enucleation of prostates (HoLEP) larger than 80 g

    NASA Astrophysics Data System (ADS)

    Kuntz, Rainer M.; Lehrich, Karin; Fayad, Amr

    2001-05-01

    In this prospective study, the efficiency of HoLEP inpatients with prostates larger than 80 grams was to be evaluated. 64 urodynamically obstructed patients with prostate glands of 103 (80-230) grams of weight underwent HoLEP (80 W, 2.0 J, 40 Hz, 550 nm bare laser fibers). The resected weight was 70 (50-200) grams, the resection time was 120.5 (83-170) min., the average resection weight was 0.7 gm/min. The postoperative catheter time was 1.3 (1-3) days. The postoperative hospital stay was 2.5 (1-7) days. HoLEP induced a significant, pronounced and immediate improvement of lower urinary tract symptoms and micturition. The symptom score decreased from 22.3 preoperatively to 5.7 one week and 2.8 one year postoperatively. The peak urinary flow rate of 4.3 ml/sec preoperatively increased to 22 ml/sec one week and 32 ml/sec one year postoperatively. The residual urine dropped from 267 ml preoperatively to 11.5 ml one week and 5.0 ml one year postoperatively. There was one incident of postoperative arterial bleeding, one patient developed urethral stricture and two patients needed a second HoLEP. HoLEP appeared to be a highly effective treatment for prostates larger than 80 grams, with excellent functional results, minor blood loss, low complication rate and very short catheter time and hospital stay.

  20. 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. PMID:24735072

  1. Magnetic order and crystal structure study of YNi{sub 4}Si-type NdNi{sub 4}Si

    SciTech Connect

    Yao, Jinlei; Isnard, O.; Morozkin, A.V.; Ivanova, T.I.; Koshkid'ko, Yu.S.; Bogdanov, A.E.; Nikitin, S.A.; Suski, W.

    2015-02-15

    Magnetic measurements and neutron powder diffraction investigation of the magnetic structure of the orthorhombic YNi{sub 4}Si-type (space group Cmmm) NdNi{sub 4}Si compound are presented. The magnetocaloric effect of NdNi{sub 4}Si is calculated in terms of the isothermal magnetic entropy change and it reaches the maximum value of –3.3 J/kg K for a field change of 50 kOe near T{sub C}=12 K. Below ∼12 K, NdNi{sub 4}Si exhibits a commensurate b-axis collinear ferromagnetic ordering with the Cmm′m magnetic space group in a zero magnetic field. At 1.5 K, the neodymium atoms have the magnetic moment of 2.37(5) μ{sub B}. The orthorhombic crystal structure and its thermal evolution are discussed in comparison with the CaCu{sub 5}-type compound. - Graphical abstract: The NdNi{sub 4}Si supplement the series of the orthorhombic derivative of the CaCu{sub 5}-type, namely the YNi{sub 4}Si-type, RNi{sub 4}Si compounds (R=Y, La, Ce, Sm, Gd–Ho). Below ∼12 K in a zero applied magnetic field, NdNi{sub 4}Si exhibits a commensurate b-axis collinear ferromagnetic ordering with the Cmm′m magnetic space group. Compared to the CaCu{sub 5}-type NdNi{sub 4}Si compound, the YNi{sub 4}Si-type counterpart has the relatively high ferromagnetic ordering temperature (9.2 K vs. 12 K), the small magnetocaloric effect (–7.3 J/kg K vs. –3.3 J/kg K for ∆H=50 kOe), and the large magnetic anisotropy at low temperatures. In contrast with CaCu{sub 5}-type NdNi{sub 4}Si, YNi{sub 4}Si-type NdNi{sub 4}Si shows distinct hysteresis loop at 2 K.We suggest that orthorhombic distortion may be used as a prospective route for optimization of permanent magnetic properties in the family of CaCu{sub 5}-type rare earth materials. - Highlights: • Below ∼12 K the YNi{sub 4}Si-type NdNi{sub 4}Si shows a ferromagnetic ordering. • MCE of NdNi{sub 4}Si reaches value of –3.3 J/kg K in 0–50 kOe near Curie point. • NdNi{sub 4}Si exhibits b-axis ferromagnetic order with the Cmm′m magnetic space

  2. Ion source

    DOEpatents

    Leung, Ka-Ngo; Ehlers, Kenneth W.

    1984-01-01

    A magnetic filter for an ion source reduces the production of undesired ion species and improves the ion beam quality. High-energy ionizing electrons are confined by the magnetic filter to an ion source region, where the high-energy electrons ionize gas molecules. One embodiment of the magnetic filter uses permanent magnets oriented to establish a magnetic field transverse to the direction of travel of ions from the ion source region to the ion extraction region. In another embodiment, low energy 16 eV electrons are injected into the ion source to dissociate gas molecules and undesired ion species into desired ion species.

  3. The Ni-rich part of the Al–Ge–Ni phase diagram

    PubMed Central

    Jandl, Isabella; Reichmann, Thomas L.; Richter, Klaus W.

    2013-01-01

    The Ni-rich part of the ternary system Al–Ge–Ni (xNi > 50 at.%) was investigated by means of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM). The two isothermal sections at 550 °C and 700 °C were determined. Within these two sections a new ternary phase, designated as τ4, AlyGe9−yNi13±x (hP66, Ga3Ge6Ni13-type) was detected and investigated by single crystal X-ray diffraction. Another ternary low temperature phase, τ5, was found only in the isothermal section at 550 °C around the composition AlGeNi4. This compound was found to crystallise in the Co2Si type structure (oP12, Pnma). The structure was identified by Rietveld refinement of powder data. The NiAs type (B8) phase based on binary Ge3Ni5 revealed an extended solid solubility of Al and the two isotypic compounds AlNi3 and GeNi3 form a complete solid solution. Based on DTA results, six vertical sections at 55, 60, 70, 75 and 80 at.% Ni and at a constant Al:Ni ratio of 1:3 were constructed. Furthermore, the liquidus surface projection and the reaction scheme (Scheil diagram) were completed by combining our results with previous results from the Ni-poor part of the phase diagram. Six invariant ternary reactions were identified in the Ni-rich part of the system. PMID:27087754

  4. Preferred orientation relationships with large misfit interfaces between Ni{sub 3}Sn{sub 4} and Ni in reactive wetting of eutectic SnPb on Ni

    SciTech Connect

    Suh, J. O.; Tu, K. N.; Wu, Albert T.; Tamura, N.

    2011-06-15

    Ni{sub 3}Sn{sub 4} grains were formed on Ni by reactive wetting between molten eutectic SnPb and thermally annealed Ni foil. Using synchrotron white beam micro x-ray diffraction analysis, two kinds of preferred orientation relationships between Ni{sub 3}Sn{sub 4} and Ni were found. The existence of preferred orientation with large interfacial misfit is suggested as a general mechanism of intermetallic compound formation in reactive solder wetting on metals.

  5. 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.

  6. Rare earth metal rich magnesium compounds RE{sub 4}NiMg (RE=Y, Pr-Nd, Sm, Gd-Tm, Lu)-Synthesis, structure, and hydrogenation behavior

    SciTech Connect

    Tuncel, Selcan; Roquefere, Jean Gabriel; Stan, Cristina; Bobet, Jean-Louis Chevalier, Bernard Gaudin, Etienne; Hoffmann, Rolf-Dieter; Rodewald, Ute Ch; Poettgen, Rainer

    2009-02-15

    The rare earth metal rich compounds RE{sub 4}NiMg (RE=Y, Pr-Nd, Sm, Gd-Tm, Lu) were synthesized from the elements in sealed tantalum tubes in an induction furnace. All compounds were investigated by X-ray diffraction on powders and single crystals: Gd{sub 4}RhIn type, space group F4-bar 3m, Z=16, a=1367.6(2) pm for Y{sub 4}NiMg, a=1403.7(3) pm for Pr{sub 4}NiMg, a=1400.7(1) pm for Nd{sub 4}NiMg, a=1386.5(2) pm for Sm{sub 4}NiMg, a=1376.1(2) pm for Gd{sub 4}NiMg, a=1362.1(1) pm for Tb{sub 4}NiMg, a=1355.1(2) pm for Dy{sub 4}NiMg, a=1355.2(1) pm for Ho{sub 4}NiMg, a=1354.3(2) pm for Er{sub 4}NiMg, a=1342.9(3) pm for Tm{sub 4}NiMg, and a=1336.7(3) pm for Lu{sub 4}NiMg. The nickel atoms have trigonal prismatic rare earth coordination. These NiRE{sub 6} prisms are condensed via common edges to a three-dimensional network which leaves voids for Mg{sub 4} tetrahedra and the RE1 atoms which show only weak coordination to the nickel atoms. The single crystal data indicate two kinds of solid solutions. The RE1 positions reveal small RE1/Mg mixing and some compounds also show Ni/Mg mixing within the Mg{sub 4} tetrahedra. Y{sub 4}NiMg and Gd{sub 4}NiMg have been tested for hydrogenation. These compounds absorb up to eleven hydrogen atoms per formula unit under a hydrogen pressure of 1 MPa at room temperature. The structure of the metal atoms is maintained with only an increase of the lattice parameters ({delta}V/V{approx}22%) if the absorption is done at T<363 K as at higher temperature a decomposition into REH{sub 2}-REH{sub 3} hydrides occurred. Moreover, the hydrogenation affects drastically the magnetic properties of these intermetallics. For instance, Gd{sub 4}NiMg exhibits an antiferromagnetic behavior below T{sub N}=92 K whereas its hydride Gd{sub 4}NiMgH{sub 11} is paramagnetic down to 1.8 K. - Graphical abstract: The Mg{sub 4} and NiGd{sub 6} units in Gd{sub 4}NiMg and Gd{sub 4}NiMgH{sub x}.

  7. Highly efficient passively Q-switched Tm,Ho:GdVO4 laser with kilowatt peak power

    NASA Astrophysics Data System (ADS)

    Du, Yanqiu; Yao, Baoquan; Liu, Wei; Cui, Zheng; Duan, Xiaoming; Ju, Youlun; Yu, Hong

    2016-04-01

    We present the experimental results on the laser characteristics of diode-pumped passively Q-switched Tm,Ho:GdVO4 and Tm,Ho:YVO4 lasers with a Cr2+:ZnS saturable absorber emitting in the 2-μm range. The Tm,Ho:GdVO4 laser exhibits better performance than the Tm,Ho:YVO4 laser. The minimum pulse duration of 32.7 ns is obtained with the pulse energy of 0.30 mJ, corresponding to the peak power of 9.1 kW. The slope efficiencies of continuous wave and passively Q-switched Tm,Ho:GdVO4 lasers are 49.9% and 36.5%, corresponding to the Q-switching efficiency of 70.2%.

  8. In vitro evaluation of mitochondrial-chloroplast subcellular localization of heme oxygenase1 (HO1) in Glycine max.

    PubMed

    Dixit, Shubham; Verma, Khushbu; Shekhawat, Gyan Singh

    2014-05-01

    Heme oxygenase1 (HO1) catalyzes the degradation of heme in to biliverdin, carbon monoxide, and ferrous ions. Its role in higher plants has been found as an antioxidant and precursor of phytochrome synthesis. The present study focuses on subcellular localization of HO1 in leaves of soybean has been investigated. Most activity appeared to be located within chloroplast due to its role in phytochrome synthesis but mitochondria also share its localization. Mitochondrial location of HO1 might be on its inner membranous space due to its role in the synthesis of electron donor species which facilitates HO1 catalyzed reaction. Study reports the co-localization of HO1 in both chloroplast and mitochondria. PMID:24158377

  9. 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.

  10. 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.

  11. Hořava-Lifshitz gravity: Detailed balance revisited

    NASA Astrophysics Data System (ADS)

    Vernieri, Daniele; Sotiriou, Thomas P.

    2012-03-01

    We attempt a critical reconsideration of “detailed balance” as a principle that can be used to restrict the proliferation of couplings in Hořava-Lifshitz gravity. We reexamine the shortcomings that have been usually associated with it in the literature and we argue that easy remedies can be found for all of them within the framework of detailed balance, and that the most persistent of them are actually related to projectability. We show that, once projectability is abandoned, detailed balance reduces the number of independent couplings by roughly an order of magnitude and imposes only one restriction that constitutes a phenomenological concern: the size of the (bare) cosmological constant is unacceptably large. Remarkably, this restriction (which is present in the projectable version as well) has been so far underappreciated in the literature. Optimists might prefer to interpret it as a potential blessing in disguise, as it allows one to entertain the idea of a miraculous cancellation between the bare cosmological constant and the (still poorly understood) vacuum energy contribution.

  12. Light sterile neutrino sensitivity of 163Ho experiments

    NASA Astrophysics Data System (ADS)

    Gastaldo, L.; Giunti, C.; Zavanin, E. M.

    2016-06-01

    We explore the sensitivity of 163Ho electron capture experiments to neutrino masses in the standard framework of three-neutrino mixing and in the framework of 3+1 neutrino mixing with a sterile neutrino which mixes with the three standard active neutrinos, as indicated by the anomalies found in short-baseline neutrino oscillations experiments. We calculate the sensitivity to neutrino masses and mixing for different values of the energy resolution of the detectors, of the unresolved pileup fraction and of the total statistics of events, considering the expected values of these parameters in the two planned stages of the ECHo project (ECHo-1k and ECHo-1M). We show that an extension of the ECHo-1M experiment with the possibility to collect 1016 events will be competitive with the KATRIN experiment. This statistics will allow to explore part of the 3+1 mixing parameter space indicated by the global analysis of short-baseline neutrino oscillation experiments. In order to cover all the allowed region, a statistics of about 1017 events will be needed.

  13. 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. PMID:26009880

  14. Removal of natural organic matter in a typical south-China source water during enhanced coagulation with IPF-PACl.

    PubMed

    Liu, Hai-long; Wang, Dong-sheng; Xia, Zhong-huani; Tang, Hong-xiao; Zhang, Jin-song

    2005-01-01

    Systematic investigation on enhancing removal of natural organic matter (NOM) using inorganic polymer flocculant (IPF), polyaluminum chloride (PACl) and polyacrylamide (PAM) was performed in a typical south-China source water. Enhanced coagulation and applying polymer flocculant-aid were compared through jar tests and pilot tests. Raw water and settled water were characterized and fractionated by resin adsorption. The results show that DOC composes major part of TOC. The DOC distribution keeps relatively stable all around the year with typical high amounts of the hydrophilic matter around 50%. The distribution between HoB, HoA and HoN varies and undergoes fluctuation with the year round. During the summer season, the HoN becomes gradually the major part in hydrophobic parts. PACI with the species being tailor-made shows little pH effect during coagulation. The enhanced coagulation dosage for PACI could be 4.5 mg/L for the typical source water. The highest TOC removal achieved 31%. To be economically, 3 mg/L dose is the optimum dosage. Although hydrophilic fractions of NOM of both treatment strategies are removed about 30%, NOM causing UV254. absorbance were well removed(about 90%). Hydrophobic bases and acids fractions are much more removed under enhanced conditions. The hydrophilic fraction could be better removed using PAM, the polymer coagulant aid. PMID:16465898

  15. Observation and modelling of the OH, HO2 and RO2 radicals at a rural site (Wangdu) in the North China Plain in summer 2014

    NASA Astrophysics Data System (ADS)

    Tan, Zhaofeng; Fuchs, Hendrik; Lu, Keding; Bohn, Birger; Broch, Sebastian; Haeseler, Rolf; Hofzumahaus, Andrease; Holland, Frank; Li, Xin; Liu, Ying; Rohrer, Franz; Shao, Min; Wang, Baolin; Wang, Ming; Wu, Yusheng; Zeng, Limin; Wahner, Andrease; Zhang, Yuanhang

    2016-04-01

    A comprehensive field campaign was carried out in summer 2014 in Wangdu located in the North China Plain. A month of continuous OH, HO2and RO2 measurements were obtained by a laser induced fluorescence system. High daytime OH, HO2 and RO2 radical concentrations were observed of which their daily maximum concentrations were (5 - 15)×106cm‑3, (3 - 14)×108 cm‑3 and (3 - 15)×108 cm‑3, respectively. A chemical box model constrained by observed trace gas compounds with state of art chemical mechanism is used to interpret the observed radical concentrations. The model underestimated the observed OH concentrations by a factor of 2 when NO is less than 100ppt in the afternoon hours. Like PRIDE-PRD2006 and CAREBEIJING2006, an additional OH recycling is required to reproduce the observed OH concentrations for the high VOC and low NOx conditions. Based on a few chemical modulation experiments we performed at the site, the determined OH interference signal were very small for the afternoon conditions. In addition, we found that observed RO2 concentrations were underestimated in the morning hours which indicated the existence of additional chemical sources of RO2 and an underestimation of the local ozone production rates in current model.

  16. Rate constants for H{sub 2}CO + O{sub 2} {yields} HCO + HO{sub 2} at high temperature

    SciTech Connect

    Michael, J. V.; Su, M.-C.; Sutherland, J. W.; Fang, D.-C.; Harding, L. B.; Wagner, A. F.

    2000-01-05

    The reaction between H{sub 2}CO and O{sub 2} has been studied in a reflected shock tube apparatus between 1633--2027 K using trioxane, (H{sub 2}CO){sub 3}, as the source of H{sub 2}CO. O-atom atomic resonance absorption spectrometry (ARAS) was used to observe absolute [O]{sub t} under conditions of low [H{sub 2}CO]{sub 0} so that most secondary reactions were negligible. Hence, the observed [O]{sub t} was the direct result of the rate controlling reaction between H{sub 2}CO and O{sub 2}. Ab initio theoretical results indicated that the process, H{sub 2}CO + O{sub 2} {yields} HCO + HO{sub 2}, is the only possible reaction. After rapid HCO and HO{sub 2} dissociations, O-atoms are then instantaneously produced from H + O{sub 2} {yields} O + OH. Using the ab initio result, variational transition state theoretical calculations (CTST) give k{sub 1} = 4.4929 x 10{sup {minus}20} T{sup 2.9116} exp{minus}18692/T cm{sup 3} molecule{sup {minus}1} S{sup {minus}1}. This theoretical result is consistent with the present experimental determinations and those at lower temperatures.

  17. ION SOURCE

    DOEpatents

    Martina, E.F.

    1958-04-22

    An improved ion source particularly adapted to provide an intense beam of ions with minimum neutral molecule egress from the source is described. The ion source structure includes means for establishing an oscillating electron discharge, including an apertured cathode at one end of the discharge. The egress of ions from the source is in a pencil like beam. This desirable form of withdrawal of the ions from the plasma created by the discharge is achieved by shaping the field at the aperture of the cathode. A tubular insulator is extended into the plasma from the aperture and in cooperation with the electric fields at the cathode end of the discharge focuses the ions from the source,

  18. 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

  19. Silencing HO-1 sensitizes SKM-1 cells to apoptosis induced by low concentration 5-azacytidine through enhancing p16 demethylation.

    PubMed

    Wang, Ping; Ma, Dan; Wang, Jishi; Fang, Qin; Gao, Rui; Wu, Weibing; Lu, Tangsheng; Cao, Lu

    2015-03-01

    Heme oxygenase-1 was reported previously as a resistance target on acute myelocytic leukemia (AML). We found that HO-1 was resistant to 5-azacytidine (AZA) treatment of myelodysplastic syndrome (MDS), and explored further the relative mechanisms. Patient bone marrow mononuclear cells (n=48) diagnosed as different levels of MDS were collected. Cell growth was evaluated by MTT assay; cell cycle and apoptosis were detected by flow cytometry; mRNA expression was assessed by real-time PCR, protein expression was analyzed through western blotting. Methylation was assessed by MSP. The survival time, and weight of mice were recorded. HO-1 overexpression was observed in SKM-1 cells after AZA treatment comparing to other cell lines. The HO-1 expression in MDS patients with high-risk was higher than in low-risk patients. After HO-1 was silenced by lentivirus-mediated siRNA, the proliferation of SKM-1 cells was effectively inhibited by low concentration AZA, and the cell cycle was arrested in the G0/G1 phase. Upregulation of p16 and changing of p16-relative cell cycle protein was observed after silencing HO-1 in AZA treated SKM-1 cells. In addition, DNMT1 was downregulated following the decrease of HO-1 expression. In vivo, silencing HO-1 inhibited SKM-1 cell growth induced by AZA in a NOD/SCID mouse model. Silencing HO-1 sensitized SKM-1 cells toward AZA, which may be attributed to the influence of HO-1 on AZA-induced p16 demethylation. HO-1 may be one of the targets that enhance the therapeutic effects of AZA on MDS malignant transformation inspiring new treatment methods for high-risk and very high-risk MDS patients in clinical practice. PMID:25585641

  20. Microstructure of Ni-Al powder and Ni-Al composite coatings prepared by twin-wire arc spraying

    NASA Astrophysics Data System (ADS)

    Wang, Ji-xiao; Wang, Gui-xian; Liu, Jing-shun; Zhang, Lun-yong; Wang, Wei; Li, Ze; Wang, Qi-xiang; Sun, Jian-fei

    2016-07-01

    Ni-Al powder and Ni-Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni-Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni3Al, Al2O3, and NiO. The Ni-Al phase and a small amount of Al2O3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni-Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and NiAl in addition to a small amount of Al2O3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, NiAl, and Ni3Al in addition to a small amount of Al and Al2O3, and NiAl and Ni3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl3 precipitates and a Ni-Al-O amorphous phase formed in the matrix of the Ni solid solution in the original state.