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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

    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.

  10. 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

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

    SciTech Connect

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

    2011-10-15

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

  3. 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 %.

  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. 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

  20. 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

  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. 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.

  16. 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.

  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. 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.

  3. 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.

  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 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

  1. 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

  2. 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.

  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. 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.

  17. 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.

  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 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  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. Preparation of electrodeposited Zn-Ni-B alloy coatings

    NASA Astrophysics Data System (ADS)

    Sakai, Taro; Kamimoto, Yuki; Ichino, Ryoichi

    2016-01-01

    We prepared Zn-Ni-B alloys with high Zn content and high corrosion resistance. The composition of the alloys was controlled by potentiostatic electrolysis. In the electroplating bath, dimethylamineborane was used as the B source. The characterization of the alloys and corrosion resistance evaluation were carried out by X-ray diffraction (XRD) analysis, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Tafel plots, and cyclic corrosion tests. All films were categorized into three groups on the basis of the results of XRD analysis, and it was found by TEM analysis that the Ni-B-type showed an amorphous structure. The Ni-B-type could contain up to 50.6 mol % Zn and showed similar or better anticorrosion properties than the amorphous Ni-B films. In the Ni-B-type, the higher the Zn content, the higher the corrosion resistance. The Zn-Ni-B alloys had almost the same electrochemical corrosion resistance and Zn content as the Zn-Ni-P alloys.

  13. 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.

  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. 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.

  17. 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

  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. 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.

  7. 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.

  8. 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.

  9. 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

  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. 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

  18. 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 ...

  19. 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,…

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. 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

  8. 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.

  9. 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.

  10. 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 ...

  11. 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.

  12. 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...

  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. 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...

  2. 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.

  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