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Sample records for mg espinhaco range

  1. Analysis of tectonic movements utilizing remote sensor products in the Southern Espinhaco (SE) region

    NASA Astrophysics Data System (ADS)

    Veneziani, Paulo; Tavaresdemattos, Juercio; Ohara, Tomoyuki

    1989-06-01

    The area under study, the Southern Espinhaco Region, Minas Gerais State, Brazil, comprises metasedimentary sequences of Proterozoic, a typical granite-greenstone belt of Archaean age, gneiss, mignatites, granulites, and metasedimentary, and mafic to felsic units attributed to undifferentiated Precambrian. The region suffered a complex geologic evolution, including polycyclic and polymetamorphic events. Deformations occurred during the deposition of sediments (synsedimentary) due to compressive forces acting repeatedly during the geologic history of the region, resulting in superimposed orogenesis. The ruptile, ruptile-ductile tectonics that were part of different events registered in the petrographic and structural record were analyzed by LANDSAT (MSS, RBV, and TM) and radar images, aeromagnetic data, and field work. The main results of this research are: identification of 7 sets of joint zones which are controlled along N-S, EW and NW-SE directions during the Archaean to Late Proterozoic events; identification of sinistral transcurrent movements along N50-60W lineaments during the compressive phase of Late Proterozoic; occurrence of different tectonic movements (compression and tension) along the main directions of fracturing; finally the analysis of lithostratigraphic and fracturing data permits to envisage the geologic history of Proterozoic evolution of the region characterized by mechanism compatible to intraplate tectonic movements (ensialic environment).

  2. Divacancies and the hydrogenation of Mg-Ti films with short range chemical order

    SciTech Connect

    Leegwater, H.; Schut, H.; Eijt, S. W. H.; Egger, W.; Baldi, A.; Dam, B.

    2010-03-22

    We obtained evidence for the partial chemical segregation of as-deposited and hydrogenated Mg{sub 1-y}Ti{sub y} films (0<=y<=0.30) into nanoscale Ti and Mg domains using positron Doppler-broadening. We exclusively monitor the hydrogenation of Mg domains, owing to the large difference in positron affinity for Mg and Ti. The electron momentum distribution broadens significantly upon transformation to the MgH{sub 2} phase over the whole compositional range. This reveals the similarity of the metal-insulator transition for rutile and fluorite MgH{sub 2}. Positron lifetime studies show the presence of divacancies in the as-deposited and hydrogenated Mg-Ti metal films. In conjunction with the relatively large local lattice relaxations we deduce to be present in fluorite MgH{sub 2}, these may be responsible for the fast hydrogen sorption kinetics in this MgH{sub 2} phase.

  3. Wide pH range for fluoride removal from water by MHS-MgO/MgCO₃ adsorbent: kinetic, thermodynamic and mechanism studies.

    PubMed

    Zhang, Kaisheng; Wu, Shibiao; Wang, Xuelong; He, Junyong; Sun, Bai; Jia, Yong; Luo, Tao; Meng, Fanli; Jin, Zhen; Lin, Dongyue; Shen, Wei; Kong, Lingtao; Liu, Jinhuai

    2015-05-15

    A novel environment friendly adsorbent, micro-nano hierarchical structured flower-like MgO/MgCO3 (MHS-MgO/MgCO3), was developed for fluoride removal from water. The adsorbent was characterized and its defluoridation properties were investigated. Adsorption kinetics fitted well the pseudo-second-order model. Kinetic data revealed that the fluoride adsorption was rapid, more than 83-90% of fluoride could be removed within 30 min, and the adsorption equilibrium was achieved in the following 4 h. The fluoride adsorption isotherm was well described by Freundlich model. The maximum adsorption capacity was about 300 mg/g at pH=7. Moreover, this adsorbent possessed a very wide available pH range of 5-11, and the fluoride removal efficiencies even reached up to 86.2%, 83.2% and 76.5% at pH=11 for initial fluoride concentrations of 10, 20 and 30 mg/L, respectively. The effects of co-existing anions indicated that the anions had less effect on adsorption of fluoride except phosphate. In addition, the adsorption mechanism analysis revealed that the wide available pH range toward fluoride was mainly resulted from the exchange of the carbonate and hydroxyl groups on the surface of the MHS-MgO/MgCO3 with fluoride anions.

  4. A Mg(2+)-dependent ecto-phosphatase activity on the external surface of Trypanosoma rangeli modulated by exogenous inorganic phosphate.

    PubMed

    Fonseca-de-Souza, André L; Dick, Claudia Fernanda; Dos Santos, André Luiz Araújo; Meyer-Fernandes, José Roberto

    2008-08-01

    In this work, we characterized a Mg(2+)-dependent ecto-phosphatase activity present in live Trypanosoma rangeli epimastigotes. This enzyme showed capacity to hydrolyze the artificial substrate for phosphatases, p-nitrophenylphosphate (p-NPP). At saturating concentration of p-NPP, half-maximal p-NPP hydrolysis was obtained with 0.23mM Mg(2+). Ca(2+) had no effect on the basal phosphatase activity, could not substitute Mg(2+) as an activator and in contrast inhibited the p-NPP hydrolysis stimulated by Mg(2+). The dependence on p-NPP concentration showed a normal Michaelis-Menten kinetics for this phosphatase activity with values of V(max) of 8.94+/-0.36 nmol p-NP x h(-1) x 10(-7) cells and apparent K(m) of 1.04+/-0.16 mM p-NPP. Mg(2+)-dependent ecto-phosphatase activity was stimulated by the alkaline pH range. Experiments using inhibitors, such as, sodium fluoride, sodium orthovanadate and ammonium molybdate, inhibited the Mg(2+)-dependent ecto-phosphatase activity. Inorganic phosphate (Pi), a product of phosphatases, inhibited reversibly in 50% this activity. Okadaic acid and microcystin-LR, specific phosphoserine/threonine phosphatase inhibitors, inhibited significantly the Mg(2+)-dependent ecto-phosphatase activity. In addition, this phosphatase activity was able to recognize as substrates only o-phosphoserine and o-phosphothreonine, while o-phosphotyrosine was not a good substrate for this phosphatase. Epimastigote forms of T. rangeli exhibit a typical growth curve, achieving the stationary phase around fifth or sixth day and the Mg(2+)-dependent ecto-phosphatase activity decreased around 10-fold with the cell growth progression. Cells maintained at Pi-deprived medium (2 mM Pi) present Mg(2+)-dependent ecto-phosphatase activity approximately threefold higher than that maintained at Pi-supplemented medium (50 mM Pi).

  5. Temperature-dependent Sellmeier equation at terahertz frequency range for 1 mol % MgO-doped stoichiometric lithium tantalate

    NASA Astrophysics Data System (ADS)

    Lee, Kyu-Sup; Ko, Do-Kyeong; Yu, Nan Ei

    2017-04-01

    We first examined a temperature-dependent Sellmeier equation for the extraordinary refractive index of MgO-doped stoichiometric LiTaO3 (MgO:SLT) crystal via frequency-tunable narrowband terahertz (THz) generation at 0.4–1.8 THz and at a low temperature range of 80–300 K. The mean deviation of Sellmeier equation fit was less than 0.3%, being equivalent with the predicted measurement uncertainty of 0.3%. The temperature effect (dn THz/dT) was 2.02 × 10‑3/K at 1 THz. Moreover, we showed the smaller birefringence for MgO:SLT than MgO-doped stoichiometric LiNbO3 at 300 K from THz time-domain spectroscopy. This study is crucial for material study itself and THz device engineering.

  6. Bounds to Hardening by Solid Solution, Precipitation and Short Range Order in Mg Binary Alloys

    NASA Astrophysics Data System (ADS)

    Cáceres, C. H.; Abaspour, Saeideh

    Miedema's coordinates are used to rank 4 model binary alloys considering the respective values of enthalpy of formation and the tendency to developing random solid solution, precipitation, short range order (SRO) and intermetallic compounds. The terminal solid solubility generally increases whereas the tendency to order decreases with decreasing heat of formation, and hardening by near-random solid solution and/or precipitation is expected to be dominant for solutes with low tendency to order, such as Al. For solutes with an intermediate tendency to order, hence solubility, such as Zn, or to form compounds, such as Gd, SRO is predicted to dominate the hardening. For solutes whose very large heat of formation leads to very high melting point intermetallics forming congruently, such as Sb, the terminal solid solubility is too low for any solute based hardening to be feasible. Implicancies for alloy design and selection regarding solute or precipitation hardening, SRO and creep resistance are discussed.

  7. Refractive Index and Absorption Coefficient of Undoped and Mg-Doped Lithium Tantalate in the Terahertz Range

    NASA Astrophysics Data System (ADS)

    Buzády, Andrea; Unferdorben, Márta; Tóth, György; Hebling, János; Hajdara, Ivett; Kovács, László; Pálfalvi, László

    2017-08-01

    Dielectric material parameters of lithium tantalate (LT) in the terahertz region have been investigated using terahertz time-domain spectroscopy (THz-TDS). Undoped congruent, undoped stoichiometric, and Mg-doped stoichiometric LT crystals were measured. The Mg content was 0.5 and 1.0 mol% for the stoichiometric composition. Index of refraction and absorption coefficient spectra were determined in the 0.3-2.0-THz frequency range for beam polarization both parallel (extraordinary polarization) and perpendicular (ordinary polarization) to the optical axis [001] of the crystal at room temperature. For the calculation of the refractive index and absorption coefficient spectra from the measured data, we used TeraMat software (Menlo System) belonging to the spectrometer. The refractive index and the absorption coefficient for stoichiometric crystals were lower than for the congruent one. In the case of stoichiometric crystals, the Mg dopant caused a slight reduction of both ordinary and extraordinary refractive index compared to the undoped crystal. However, the presence of Mg did not reduce the absorption coefficient either for the ordinary or for the extraordinary polarization. In order to fit the measurement data, a Lorentz oscillator model was used. Good agreement was obtained between the measured data and the fitting curves by using the Lorentz oscillator model containing three terms.

  8. High resolution Raman and neutron investigation of Mg(BH4)2 in an extensive temperature range.

    PubMed

    Giannasi, A; Colognesi, D; Ulivi, L; Zoppi, M; Ramirez-Cuesta, A J; Bardají, E G; Roehm, E; Fichtner, M

    2010-03-04

    Raman spectra of Mg(BH(4))(2) have been measured in an extensive temperature range, from 15 to 473 K. Taking into account the high temperature conversion from the alpha to the beta phase, we have observed evident signatures of this phase transition and determined the Raman vibrational spectrum of each phase. The neutron scattering spectra of the beta phase sample were also recorded. The present experimental results have been compared to the density functional theory calculations available in the literature, and a substantial agreement has been found.

  9. Microstrain and short-range ordering of Ca and Mg cations in pyrope-grossular garnet system

    NASA Astrophysics Data System (ADS)

    DU, W.; Clark, S. M.; Walker, D.

    2016-12-01

    Synchrotron X-ray diffraction (XRD) was used to measure the unit cell parameters of synthetic pyrope (Mg3Al2Si3O12), grossular (Ca3Al2Si3O12) and four intermediate garnet solid solutions at the Advanced Light Source, Lawrence Berkeley National Laboratory (ALS on beamline 12.2.2 at room temperature and pressure). Analysis of X-ray diffraction profiles by using Williamson-Hall plots shows that XRD peak width getting broadened with diffraction angle and the degree of the XRD peak broadening changes with garnet composition. Microstrain in the garnet structure, rather than grain size variation, is the principal reason for the observed XRD peak broadening. Garnets with compositions Py80Gr20 and Py20Gr80, close to the negligibly strained end members pyrope (Py100) and grossular (Gr100), have large microstrains, which is contrast to garnet with intermediate composition Py40Gr60, which almost has no microstrain. This compositional dependent elastic structural strain shows a complex correlation with other nonideal mixing properties along the pyrope-grossular binary, for example, excess volume, mixing enthalpy, thermal expansion etc. The observation that the two end member garnets carry almost zero microstrain indicates that the microstrain calculated from XRD peak broadening is related to the Mg-Ca substitution. A different degree of short-range ordering of Ca-Mg in dodecahedral site that develops during annealing after MA crystallization may be partly responsible for these nonideal-mixing phenomena along the pyrope-grossular join.

  10. Effect of Water Vapor Pressure on Fatigue Crack Growth in Al-Zn-Cu-Mg Alloy Over Wide-Range Stress Intensity Factor Loading

    DTIC Science & Technology

    2014-05-07

    Lee United States Air Force Academy Title: Effect of Water Vapor Pressure on Fatigue Crack Growth in Al-Zn-Cu- Mg Alloy Over Wide-range Stress...Al- li-Cu- Mg alloys in vacuum, Metall Trans A, 24 (1993) 1807-1817. [46] R.D. Carter, E.W. Lee, E.A. Starke, C.J. Beevers, The Effect of...Vapor Pressure on Fatigue Crack Growth in Al-Zn-Cu- Mg Alloy Over Wide-range Stress Intensity Factor Loading J.T. Bums1, R.W. Bush2, J. Ai1, J.L Jones1

  11. The Impact of Azilsartan Medoxomil Treatment (Capsule Formulation) at Doses Ranging From 10 to 80 mg: Significant, Rapid Reductions in Clinic Diastolic and Systolic Blood Pressure.

    PubMed

    Perez, Alfonso; Cao, Charlie

    2017-03-01

    In this phase 2, multicenter, parallel-group, double-blind, dose-ranging study, hypertensive adults (n=449) were randomized to receive one of five doses of a capsule formulation of azilsartan medoxomil (AZL-M; 5, 10, 20, 40, 80 mg), olmesartan medoxomil (OLM) 20 mg, or placebo once daily. The primary endpoint was change in trough clinic diastolic blood pressure (DBP) at week 8. AZL-M provided rapid statistically and clinically significant reductions in DBP and systolic blood pressure (SBP) vs placebo at all doses except 5 mg. Placebo-subtracted changes were greatest with the 40 mg dose (DBP, -5.7 mm Hg; SBP, -12.3 mm Hg). Clinic changes with AZL-M (all doses) were statistically indistinguishable vs OLM, although there were greater reductions with AZL-M 40 mg using 24-hour ambulatory blood pressure. Adverse event frequency was similar in the AZL-M and placebo groups. Based on these and other findings, subsequent trials investigated the commercial AZL-M tablet in the dose range of 20 to 80 mg/d. ©2016 Wiley Periodicals, Inc.

  12. High-resolution autoionizing line spectra of Mg II and Al III in the 160--260-A range emitted from a Penning ionization discharge plasma

    SciTech Connect

    Finkenthal, M.; Litman, A.; Mandelbaum, P.; Stutman, D.; Schwob, J.L.

    1988-08-01

    Spectra of aluminum and magnesium emitted from a Penning ionization discharge have been recorded in the XUV range by 2-m grazing-incidence spectrometer. Autoionizing satellite lines, originating from transitions between core excited levels lying in the continuum and ground or lowest excited states of the Na I-like Al III and Mg II, have been classified. Their implication for ionization cross-section estimates and XUV laser research is discussed.

  13. Effects of atomic short-range order on properties of the PbMg1 /3Nb2 /3O3 relaxor ferroelectric

    NASA Astrophysics Data System (ADS)

    Prosandeev, Sergey; Bellaiche, L.

    2016-11-01

    The effect of atomic short-range order on the macroscopic and microscopic properties of the prototype of relaxor ferroelectrics, that is, lead magnesium niobate Pb (Mg1 /3Nb2 /3) O3 (PMN), is studied via the combination of an annealing technique and a large-scale effective Hamiltonian method. The investigated short-range order gradually varies from the case of fully disordered solid solutions to the situation for which the first three nearest-neighboring shells of the B lattice of PMN adopt a rocksalt ordering between a sublattice made of pure Nb ions and a randomly distributed sublattice consisting of 2/3 of Mg and 1/3 of Nb. The characteristic temperatures of relaxor ferroelectrics (namely, the Burns, so-called T*, and depolarizing temperatures) significantly increase when strengthening this short-range chemical order, which is accompanied by an overall enhancement of the size of the polar nanoregions as well as of some antiferroelectric interactions. These results can be understood by the fact that chemical short-range order strongly modifies the internal electric fields felt by the Pb ions.

  14. Critical current densities and n-values of MgB2 strands over a wide range of temperatures and fields

    NASA Astrophysics Data System (ADS)

    Li, G. Z.; Yang, Y.; Susner, M. A.; Sumption, M. D.; Collings, E. W.

    2012-02-01

    Transport measurements of critical current density, Jct, in monocore powder-in-tube MgB2 strands have been carried out at temperatures, T, of from 4.2 to 40 K, and in transverse fields, B, of up to 14 T. Processing methods used were conventional continuous tube forming/filling (CTFF) and internal magnesium diffusion (IMD). Strands with several powder compositions were measured, including binary (undoped) MgB2, 2% carbon doped MgB2, and 3% carbon doped MgB2. Magnetization loops (M-B) were also measured, and magnetic critical current density, Jcm, values extracted from them. The transport, Jct(B) and magnetic, Jcm(B), critical current densities were compared. Also studied was the influence of doping on the resistively measured irreversibility field, Birr, and upper critical field, Bc2. Critical current densities, Jct, and n-values were extracted from transport measurements and were found to be universally related (for all B and T) according to n\\propto {J}_{{ct}}^{m} in which m = 0.52 ± 0.11. Likewise n was found to be related to B according to n ∝ B-p with a T-dependent p in the range of about 0.08-0.21. Further analysis of the field (B) and temperature (T) dependences of n-value resulted in an expression that enabled n(B,T), for all B and T, to be estimated for a given strand based on the results of transport Jct(B) measurements made at one arbitrarily chosen temperature.

  15. The 10 μm band in amorphous MgSiO3: the influence of medium-range structure, defects and thermal processing

    NASA Astrophysics Data System (ADS)

    Thompson, S. P.; Parker, J. E.; Tang, C. C.

    2012-09-01

    Context. Variations in the 10 μm amorphous silicate band profile between different environments have been variously attributed to differences in composition, grain processing or macroscopic constitution (e.g. compact versus aggregate grains). However the relationship with mineralogical structure has remained poorly defined. Aims: The relationship between the 10 μm band and medium-range (~2-20 Å) structure is investigated. Methods: Synchrotron X-ray scattering, Fourier transform infrared and Raman spectroscopy are used to relate changes in medium-range structure to changes in the 10 μm band profile for amorphous MgSiO3 annealed at temperatures leading up to crystallisation. Results: Raman and X-ray data show a build up of strain within the silicate network, which is released between ~400-550 °C, causing a relaxation of both the Si-O-Si bond angle and Si-O bond length. Decomposing the 10 μm band at each temperature step shows SiO3 is the initially dominant component and increases in proportion as other species become incorporated into the silicate structure. However at ~400 °C the proportion of SiO3 decreases as species with greater numbers of non-bridging oxygens form. The coincidence with strain release implies a breakup of larger tetrahedral structures. Conclusions: We identify a correspondence between the spectral response at 10 μm of amorphous MgSiO3 and the evolution of its structural state at medium-range distances. The dependence of the 10 μm band on medium-range structure may account for the hitherto poor correlation between composition and band behaviour, variations in the 10 μm band observed in other silicates of similar compositions, or, between observed bands in different astronomical settings.

  16. Dry Sliding Wear Behavior and Subsurface Microstructure Evolution of Mg97Zn1Y2 Alloy in a Wide Sliding Speed Range

    NASA Astrophysics Data System (ADS)

    An, J.; Xuan, X. H.; Zhao, J.; Sun, W.; Liang, C.

    2016-12-01

    The wear properties of Mg97Zn1Y2 alloy were investigated using the pin-on-disk wear machine within a load range of 20-380 N and a sliding speed range of 0.2-4.0 m/s. Analysis of worn surfaces using scanning electron microscope and energy-dispersive x-ray spectrometer revealed that wear mechanisms including abrasion + oxidation, delamination accompanied by heavy surface oxidation and delamination operated in mild wear regime, while wear mechanisms such as severe plastic deformation, severe plastic deformation accompanied by spallation of oxidation layer and surface melting prevailed in severe wear regime. The microstructural evolution and hardness change in subsurfaces were examined by optical microscopy and hardness tester. The transformation of surface material from the deformed into dynamic recrystallization (DRX) microstructure was observed before and after mild-to-severe transition. The reason for mild-to-severe wear transition was identified as the transformation of strain hardening to DRX softening in subsurface. Mg97Zn1Y2 alloy has a superior mild-to-severe wear transition resistance to AZ alloys because of its higher recrystallization temperature. A novel model for evaluating the critical surface temperature of mild-to-severe wear transition was established using DRX kinetics.

  17. Thermodynamic and Structural Properties of liquid Mg2SiO4 at high temperatures and pressure in the range 0-150 GPa from Molecular Dynamics Simulation

    NASA Astrophysics Data System (ADS)

    Martin, B.; Spera, F.; Nevins, D.

    2006-12-01

    Growing interest in the dynamics of magma oceans and melting within the terrestrial planets highlights the need for developing equations of state (EOS) and transport properties of molten silicate multicomponent solutions at high temperature and pressure. We report Molecular Dynamics simulations of liquid Mg2SiO4, an important component of the upper mantle. An interatomic effective pair potential that includes Coulomb forces, Born exponential electron repulsion and van der Waals dipolar attractive forces was used with parameters from Matsui (Mineral. Mag, 58A, 571-572, 1994). 50 state points were studied in the NEV microcanonical ensemble with 8001 particles (1143 formula units) each for 50 ps (1 fs timestep). Liquid densities range from 2750 kg/m3 to 4500 kg/m3 with temperature and pressure in the range 2000- 4500 K and 0-150 GPa, respectively. Atom trajectories were post-processed to obtain a comprehensive view of nearest neighbor coordination statistics, internal energy, isochoric heat capacity, and tracer diffusivities of Mg, Si and O at all state points. Computed potential energies scale linearly in T^{3/5} along isochors facilitating EOS development by allowing robust interpolation. First nearest neighbor coordination statistics show a continuous decrease in ^{[4]}Si and increase in ^{[5]}Si and ^{[6]}Si with increasing pressure along an isotherm. In distinction, the abundance of ^{[1]}O (O with one nearest Si neighbor) is roughly constant at about 70%, with ^{[0]}O and ^{[2]}O both at about 15% as pressure increases along an isotherm. Oxygen tracer diffusivity is ~6.7x10-9 m2/s at 9.8 GPa and 3088 K. Mg and Si tracer diffusivities 1.7 and 0.8 that of oxygen, respectively. Using the Stokes-Einstein and Eyring relations between shear viscosity and oxygen tracer diffusivity, a shear viscosity of ~2.1x10-3 Pa s is estimated for molten Mg2SiO4 at 10 GPa and 3100 K. Liquid density computed by MD compares very well with liquid density inferred from experimental

  18. Short- and long-range binding of Be with Mg in the X1Σ+ ground state and in the A1Π excited state

    NASA Astrophysics Data System (ADS)

    Kerkines, Ioannis S. K.; Nicolaides, Cleanthes A.

    2012-09-01

    We present results of configuration-interaction (CI) computations of wavefunctions and of properties of the first two singlet states, X1Σ+ and A1Π, of the, as yet unobserved, BeMg polar molecule, for internuclear distances in the range [2.5-1000] Å. The X1Σ+ state is very weakly bound, (De = 469.4 cm-1 at Re = 3.241 Å), whereas the A1Π state, which correlates with the excited dissociation channel [Mg KL3s3p1Po + Be 1s22s2 1S], is bound rather strongly (De = 19 394 cm-1 (55.5 kcal/mol) at Re = 2.385 Å). The X1Σ+ state supports 12 vibrational levels, for which vibrationally averaged dipole moments, ⟨μ⟩υ, were obtained, while 71 vibrational levels were found for A1Π. For the level (X1Σ+), ⟨μ⟩0 = 0.213 D. The υ″ = 7 and 8 X1Σ+ vibrational levels are found to have the highest probability to be reached via emission from the lowest lying vibrational levels of A1Π. The work had a dual outcome: First, it explored consequences of different choices of the state-specific reference "Fermi-sea" space ("active" space), which is required for the construction and execution of the multiconfigurational "complete active space self-consistent field" calculations and the subsequent multi-reference CI calculations. In this context, comparisons with results on the weakly bound ground states of the homonuclear Be2 and Mg2 molecules were made. Second, it produced reliable data for the short- as well as the long-range parts of the potential energy curve (PEC). Such information is relevant to analyses concerning cold and ultra-cold Physics and Chemistry. For example, accurate fits to the X1Σ+ PEC, which was computed to nano-Hartree accuracy, with account for basis-set-superposition error, produced the C6 and C8 dispersion coefficients as 364.3 ± 1.1 a.u. and 28 000 ± 500 a.u., respectively. The result for C6 is in excellent agreement with that of Derevianko et al. [At. Data Nucl. Data Tables 96, 323 (2010), 10.1016/j.adt.2009.12.002], (364 ± 4 a.u.), that was

  19. Broad range tuning of structural and optical properties of Zn x Mg1-x O nanostructures grown by vapor transport method

    NASA Astrophysics Data System (ADS)

    Vanjaria, Jignesh V.; Azhar, Ebraheem Ali; Yu, Hongbin

    2016-11-01

    One-dimensional (1D) Zn x Mg1-x O nanomaterials have drawn global attention due to their remarkable chemical and physical properties, and their diverse current and future technological applications. In this work, 1D ZnMgO nanostructures with different magnesium concentrations and different morphologies were grown directly on zinc oxide-coated silicon substrates by thermal evaporation of zinc oxide, magnesium boride and graphite powders. Highly well-defined Mg-rich ZnMgO nanorods with a rock salt structure and Zn-rich ZnMgO nanostructures with a wurtzite structure have been deposited individually by careful optimization of the source mixture and process parameters. Structural and optical properties of the deposited products were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy. Cathodoluminescence measurements demonstrate strong dominant peaks at 3.3 eV in Mg poor ZnMgO nanostructures and 4.8 eV in Mg rich nanostructures implying that the ZnMgO nanostructures can be used for the fabrication of deep UV optoelectronic devices. A mechanism for the formation and achieved diverse morphology of the ZnMgO nanostructures was proposed based on the characterization results.

  20. The role of melt-rock interaction in the formation of Quaternary high-MgO potassic basalt from the Greater Khingan Range, northeast China

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Qiang; Chen, Li-Hui; Wang, Xiao-Jun; Zhong, Yuan; Yu, Xun; Zeng, Gang; Erdmann, Saskia

    2017-01-01

    Melt-rock interaction between ascending melt and peridotite results in mantle metasomatism and also leads to compositional modification of the primary melt. While this process is known to occur, it is less well understood how the reactions and the composition of the resulting magma temporally evolve. Here whole-rock major and trace element, Sr-Nd-Pb-Hf isotopes, and olivine major element composition of Quaternary Nuominhe basalts in the Greater Khingan Range of northeast China are presented to unravel how melt-rock interaction modified the composition of the high-MgO potassic basalts as time progressed. The Nuominhe basalts are predominantly basanite with high MgO (8.1-16.8 wt %) and high total alkali content (K2O + Na2O = 6.0-9.2 wt %). They have high K2O/Na2O ratios (K2O/Na2O = 0.77-1.24) and low SiO2 and Al2O3 content (SiO2 = 44.4-48.7 wt %, Al2O3 = 10.5-13.2 wt %). They are characterized by enrichment in strongly incompatible elements, positive Ba, K, and Sr and negative Th, U, Zr, Hf, and Ti anomalies, similar to the composition of enriched mantle (EM1)-type oceanic island basalts (OIBs). Their isotopic composition also compares to that of EM1-type OIBs (i.e., with 87Sr/86Sr = 0.70467-0.70483, ɛNd = -4.1 to -1.5, ɛHf = -0.3 to 2.3, 206Pb/204Pb = 17.03-17.36). These elemental and isotopic characteristics are consistent with the interpretation that the potassium-rich melts were derived from recycled crustal materials with EM1 signature. Phlogopite-bearing mantle xenoliths and zoned olivine xenocrysts with high Fo89-92 and low CaO (<0.1 wt %) core and low Fo75-86 and high CaO (>0.1 wt %) rim composition record interaction between the ascending melt and mantle peridotite. Basalts erupted during late stages (Late Pleistocene and Holocene) of activity at the Nuominhe volcanic field show notably higher SiO2 content, Rb/Nb, Ba/Nb, K/La, and Ba/La, and lower MgO content than early-stage basalts (Early and Middle Pleistocene), which we infer to reflect a temporally

  1. Epitaxial Ti1- xWxN alloys grown on MgO(001) by ultrahigh vacuum reactive magnetron sputtering: Electronic properties and long-range cation ordering

    NASA Astrophysics Data System (ADS)

    Tian, F.; D'Arcy-Gall, J.; Lee, T.-Y.; Sardela, M.; Gall, D.; Petrov, I.; Greene, J. E.

    2003-01-01

    Epitaxial Ti1- xWxN alloys with 0<=x<=0.6 were grown on MgO(001) substrates at 500 °C by ultrahigh vacuum reactive magnetron sputtering from Ti and W targets in pure N2. X-ray diffraction, transmission electron microscopy (TEM), and cross-sectional TEM show that the 0.3-μm-thick Ti1- xWxN(001) alloys are single crystals with the B1-NaCl structure. Rutherford backscattering spectroscopy investigations indicate that alloys with x>=0.05 are slightly overstoichiometric with N/(Ti+W)=1.06+/-0.05. The alloy lattice parameter a⊥ along the film growth direction is 4.251 Å, irrespective of the WN concentration, for x<=0.41 and decreases slightly at higher concentrations. TEM analyses show that Ti0.5W0.5N(001) alloys have long-range CuPt-type atomic ordering on the cation sublattice. The room-temperature resistivity increases linearly from 13 μΩ cm for TiN to 287 μΩ cm for Ti0.42W0.58N due primarily to alloy scattering while the temperature coefficient of resistivity is positive in Ti1- xWxN alloys with x<=0.21 and negative for x>0.21 due to weak charge carrier localization. The superconducting critical temperature Tc of Ti1- xWxN alloys initially increases with x, due to a larger density of states at the Fermi level, consistent with valence band x-ray photoelectron spectroscopy measurements. Tc reaches a maximum of 6.67 K at x=0.21 and decreases for larger x values.

  2. Measurements of proton induced γ-ray emission cross sections on MgF2 target in the energy range 1.95-3.05 MeV

    NASA Astrophysics Data System (ADS)

    Zamboni, I.; Siketić, Z.; Jakšić, M.; Bogdanović Radović, I.

    2015-01-01

    In this work we present differential cross sections for γ-ray emission from the reactions 19F(p,p‧γ)19F (Eγ = 110, 197, 1236 and 1349 + 1357 keV), 24Mg(p,p‧γ)24Mg (Eγ = 1369 keV) and 25Mg(p,p‧γ)25Mg (Eγ = 390, 585 and 975 keV). Differential cross sections were measured for proton energies from 1.95 to 3.05 MeV with a 15 keV step and beam energy resolution of 0.06%. Thin reference standard, 54.1 μg/cm2 of MgF2 deposited on thin Mylar foil with additionally evaporated 4 nm Au layer, was used as a target. The γ-rays were detected by a 20% relative efficiency HPGe detector placed at an angle of 135° with respect to the beam direction, while the backscattered protons were collected using silicon surface barrier detector placed at the scattering angle of 165°. Obtained cross sections were compared with the previously measured data available from the literature.

  3. Experimental investigation of talc solubility in H sub 2 O-MgCl sub 2 -NaCl-HCl fluids in the range 500-700C, 2 kb

    SciTech Connect

    Grabman, K.B.; Popp, R.K. )

    1991-10-01

    The equilibrium solubility of the talc-quartz mineral assemblage in H{sub 2}O-MgCl{sub 2}-NaCl-HCl fluids at 2 kb and temperatures in the range 500-700C has been determined using rapid-quench hydrothermal techniques. At 500C, the concentration of Mg measured in the fluid after quench decreased in a systematic, nonlinear fashion with increasing concentrations of NaCl, from 2.8 m Mg in NaCl-free solutions to 1.5 m in 5.1 m NaCl. In contrast, at 600 and 700C Mg molalities increased with increasing NaCl molalities. At 600C, the concentration of Mg increased from 0.072 to 0.12 m as the concentration of NaCl increased from 0.0 to 6.1 m. At 700C, Mg molality increased from an NaCl-free value of 0.0078 m, to 0.031 m in 6.3 m NaCl. The observed solubilities were compared to concentrations of aqueous species calculated by solving the series of mass-action and mass-balance equations that describe the activities and molalities of the relevant species in the fluid. It is concluded that at 500C, MgCl{sub 2}{sup 0}, MgCl+, and Mg{sup 2+} are the only Mg-species necessary to account for the observed behavior. The calculations suggest that the decrease in Mg results from both the increasing concentrations of Cl{sup {minus}} as NaCl concentration increases, and the changing dielectric properties of the fluid. At 600 and 700C, the presence of Mg-species in addition to MgCl{sub 2}{sup 0}, MgCl{sup +}, and Mg{sup 2+} may be required to describe the increased solubility observed in the experiments. Use of the slope-quantification method for identifying aqueous species indicates that higher order Mg-Cl species or Na-Mg-Cl species are possible, but the precision of the technique is not sufficient to uniquely identify the species.

  4. Temperature increase due to Joule heating in a nanostructured MgO-based magnetic tunnel junction over a wide current-pulse range.

    PubMed

    Jeong, Boram; Lim, Sang Ho

    2011-07-01

    The temperature increase due to Joule heating in a nanopillar of a magnetic tunnel junction sandwiched by top and bottom electrodes was calculated by the finite element method. The results for the critical condition for the current-induced magnetization switching measured over a wide current-pulse range were taken from the literature. At long pulse widths, the temperature increase was solely dependent on the magnitude of the critical current density. However, no saturation in the temperature increase occurred for short pulse widths. In this case, the temperature increase additionally depended on the pulse width, so that a broad maximum occurred in the pulse width (or the critical current density) dependence of the temperature increase. The original results for the critical condition were corrected by accounting for the temperature increase and these corrected results, together with the Slonczewski equation, were used to extract an accurate value for the thermal stability factor.

  5. Merging multireference perturbation and density-functional theories by means of range separation: Potential curves for Be{sub 2}, Mg{sub 2}, and Ca{sub 2}

    SciTech Connect

    Fromager, Emmanuel; Jensen, Hans Joergen Aa.

    2010-02-15

    A rigorous combination of multireference perturbation theory and density functional theory (DFT) is proposed. Based on a range separation of the regular two-electron Coulomb interaction, it combines a short-range density functional with second-order strongly contracted n-electron valence state perturbation theory (sc-NEVPT2). The huge advantage of the sc-NEVPT2 approach is that the density is unchanged through first order due to a generalized-Brillouin-type theorem so that the computationally cumbersome self-consistency contribution of short-range DFT to the second-order energy correction equals zero. The method yields very promising results for the van der Waals systems Be{sub 2}, Mg{sub 2}, and Ca{sub 2}; including the multireference system Be{sub 2}.

  6. Relaxor-like ferroelectric behaviour favoured by short-range B-site ordering in 10% Ba{sup 2+} substituted MgFe{sub 2}O{sub 4}

    SciTech Connect

    Chithra Lekha, P.; Ramesh, G.; Revathi, V.; Subramanian, V.

    2014-05-01

    Graphical abstract: - Highlights: • Mechanism driving polarization in MgFe{sub 2}O{sub 4} is the Maxwell–Wagner polarization. • But Raman studies confirm the existence of local P4{sub 1}22/P4{sub 3}22 symmetry in MgFe{sub 2}O{sub 4}. • Ba{sup 2+} substitution increases ferroelectric ordering, ΔT{sub m} span, and masks electronic contribution. - Abstract: Using the molten salt method, pristine and Ba{sup 2+} substituted MgFe{sub 2}O{sub 4} are prepared. The relaxor-like behaviour observed in the dielectric dispersion indicates the existence of B-site short-range ordering with the local P4{sub 1}22/P4{sub 3}22 symmetry which is confirmed by the Raman spectroscopy. The paper further analyses the origin of polarization using Maxwell–Wagner fit and Nyquist plot. This work suggests a possible way to increase the relaxor-like ferroelectric ordering, larger span of relaxation temperature (ΔT{sub m}) and the effective masking of electronic contribution by the substitution of Ba{sup 2+} ion.

  7. Strictly linear trinuclear Dy-Ca/Mg-Dy single-molecule magnets: the impact of long-range f-f ferromagnetic interactions on suppressing quantum tunnelling of magnetization leading to slow magnetic relaxation.

    PubMed

    Zhang, Wan-Ying; Tian, Yong-Mei; Li, Hong-Feng; Chen, Peng; Zhang, Yi-Quan; Yan, Peng-Fei; Sun, Wen-Bin

    2017-06-27

    The synthesis, structural characterization and magnetic properties of four heterometallic complexes with formulas Ln2M(OQ)8 [Ln(iii) = Dy, M(ii) = Ca (1), Mg (2); Ln(iii) = Er, M(ii) = Ca (3), Mg (4); HOQ = 8-hydroxyquinoline] are reported. Complexes display a perfectly linear arrangement of three metal ions involving two terminal Ln(iii) ions and one central alkaline earth M(ii) ion, and they are bridged by three phenolato oxygen atoms from three 8-hydroxyquinoline ligands. Direct-current (dc) magnetic susceptibility studies show that there exists a long-range ferromagnetic (FM) interaction between two f-electronic centers in Dy-based complexes 1 and 2 albeit they are separated by diamagnetic alkaline earth ions, and the FM interaction has been successfully reproduced by ab initio calculations. Alternating current (ac) magnetic susceptibility measurements indicate that complexes 1 and 2 exhibit significant single-molecule magnet (SMM) behaviors. This is mostly attributed to the parallel magnetic axes of individual Dy(iii) sites aligning closely to the Dy-M-Dy direction, and the linearly extending magnetic susceptibility tensors of each ion lead to the FM interaction. The dc and ac susceptibility studies of the intramolecularly diluted complexes reveal that the f-f coupling suppresses the QTMs significantly in the absence of the external magnetic field.

  8. LiF:Mg,Ti TLD response as a function of photon energy for moderately filtered x-ray spectra in the range of 20-250 kVp relative to {sup 60}Co

    SciTech Connect

    Nunn, A. A.; Davis, S. D.; Micka, J. A.; DeWerd, L. A.

    2008-05-15

    The response of LiF:Mg,Ti thermoluminescent dosimeters (TLDs) as a function of photon energy was determined using irradiations with moderately filtered x-ray beams in the energy range of 20-250 kVp relative to the response to irradiations with {sup 60}Co photons. To determine if the relative light output from LiF:Mg,Ti TLDs per unit air kerma as a function of photon energy can be predicted using calculations such as Monte Carlo (MC) simulations, measurements from the x-ray beam irradiations were compared with MC calculated results, similar to the methodology used by Davis et al. [Radiat. Prot. Dosim. 106, 33-43 (2003)]. TLDs were irradiated in photon beams with well-known air kerma rates using the National Institute of Standards and Technology traceable M-series x-ray beams in the range of 20-250 kVp. For each x-ray beam, several sets of TLDs were irradiated for times corresponding to different air kerma levels to take into account any dose nonlinearity. TLD light output was then compared to that from several sets of TLDs irradiated at similar corresponding air kerma levels using a {sup 60}Co irradiator. The MC code MCNP5 was used to account for photon scatter and attenuation in the holder and TLDs and was used to calculate the predicted relative TLD light output per unit air kerma for irradiations with each of the experimentally used photon beams. The measured relative TLD response as a function of photon energy differed by up to 13% from the MC calculations. We conclude that MC calculations do not accurately predict the relative response of TLDs as a function of photon energy, consistent with the conclusions of Davis et al. [Radiat. Prot. Dosim. 106, 33-43 (2003)]. This is likely due to complications in the solid state physics of the thermoluminescence process that are not incorporated into the simulation.

  9. Equivalent magnetic noise reduction at high frequency range due to polarized direction optimization in Terfenol-D/Pb(Mg1/3Nb2/3)O3-PbTiO3 magnetoelectric laminate sensors

    NASA Astrophysics Data System (ADS)

    Fang, Cong; Ma, Jiashuai; Yao, Meng; Di, Wenning; Lin, Di; Xu, Haiqing; Wang, Wei; Luo, Haosu

    2017-02-01

    In this paper, we investigate the responsivities and output voltage noise power spectral densities of magnetoelectric (ME) laminate sensors, consisting of length magnetized Terfenol-D alloys and transverse/width poled Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMNT) crystals (i.e. L-T mode and L-W mode respectively), which are directly integrated with custom-build low noise charge amplifier circuits. Both the theoretical analyses and experimental results prove that the L-W mode sensor with the optimized polarized direction of the PMNT plate possesses lower magnetic detection limit at the interested high frequency range of 10 kHz≤f≤50 kHz. The equivalent magnetic noise (EMN) of the L-W mode sensor is 0.78 pT/Hz1/2 at 30 kHz, which is about 1.7 times lower than the 1.35 pT/Hz1/2 for conventional L-T mode sensor. Furthermore, an effective method of using operational amplifiers with low equivalent input noise voltage and employing ME laminate composites with high voltage coefficient to reduce the EMNs of the ME laminate sensors at high frequency range has been established.

  10. Experimental binding energies for the metal complexes [Mg(CH3OH)n](2+), [Ca(CH3OH)n](2+), and [Sr(CH3OH)n](2+) for n in the range 4-20.

    PubMed

    Bruzzi, E; Stace, A J

    2014-10-09

    A supersonic source of clusters has been used to prepare neutral complexes of methanol in association with an alkaline earth metal atom. From these complexes the following metal-containing dications have been generated through electron ionization: [Mg(CH3OH)n](2+), [Ca(CH3OH)n](2+), and [Sr(CH3OH)n](2+), and for n in the range 4-20, kinetic energy release measurements following the evaporation of a single molecule have been undertaken using a high resolution mass spectrometer. Using finite heat bath theory, these data have been transformed into binding energies for individual methanol molecules attached to each of the three cluster systems. In the larger complexes (n > 6) the results exhibit a consistent trend, whereby the experimental binding energy data for all three metal ions are similar, suggesting that the magnitude of the charge rather than charge density influences the strength of the interaction. From a comparison with data recorded previously for (CH3OH)nH(+) it is found that the 2+ charge on a metal ion has an effect on the binding energy of molecules in complexes containing up to 20 solvent molecules. The results recorded for [Ca(CH3OH)n](2+) show evidence of a very marked transition between n = 6 and 7, which is thought to coincide with the completion of a primary solvation shell and the onset of molecules starting to occupy a second and most probably a third shell.

  11. Differential cross section measurements of 27Al(p,p/γ)27Al and 27Al(p,αγ)24Mg reactions in the energy range of 1.6-3.0 MeV

    NASA Astrophysics Data System (ADS)

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.; Sharifzadeh, N.; Fathollahi, V.

    2015-11-01

    In this work measurement of differential cross sections of 27Al(p,p/γ)27Al (Eγ = 844, 1014 keV) and 27Al(p,αγ)24Mg (Eγ = 1369 keV) nuclear reactions in the proton energy range of 1.6-3.0 MeV are described and the measured values are presented. Thin Al target was prepared by evaporating a 26 μg/cm2 Al onto a 129 μg/cm2 self-supporting Ag film. The gamma-rays and backscattered protons were detected simultaneously. The gamma-rays and protons were collected by an HPGe detector placed at an angle of 90° with respect to beam direction and an ion implanted Si detector placed at a scattering angle of 165°, respectively. In this experimental setup the great advantage is that differential cross sections could be independent on absolute values of the collected beam charge. The overall systematic uncertainty of cross sections was estimated to be ±9% while statistical errors were less than ±5%.

  12. Oxygen Isotopes of Chondrules in the Queen Alexandra Range 99177 CR3 Chondrite: Further Evidence for Systematic Relationships Between Chondrule Mg# and Δ^1^7O and the Role of Ice During Chondrule Formation

    NASA Astrophysics Data System (ADS)

    Tenner, T. J.; Nakashima, D.; Ushikubo, T.; Kita, N. T.; Weisberg, M. K.

    2012-03-01

    QUE 99177 chondrules steadily rise in Δ^1^7O (-5 to -1 ‰) as Mg# decreases (99 to 97). Addition of +Δ1^7O H_2O ice to dry precursors could reduce chondrule Mg# (by oxidation during formation) while increasing Δ^1^7O. Estimated H_2O ice Δ^1^7O is 0.5 to 6‰.

  13. Inelastic electronic excitation and electron transfer processes in collisions between Mg(3 {sup 1}S{sub 0}) atoms and K{sup +}({sup 1}S{sub 0}) ions studied by crossed beams in the 0.10-3.80-keV energy range

    SciTech Connect

    Sabido, M.; Andres, J. de; Sogas, J.; Lucas, J.M.; Alberti, M.; Bofill, J.M.; Aguilar, A.

    2005-09-22

    Inelastic and charge-transfer excitation processes in collisions between ground-state neutral Mg atoms and K{sup +} ions have been studied by means of a crossed molecular-beam technique. Decay fluorescent emissions from Mg(3 {sup 1}P{sub 1}),Mg(4 {sup 3}S{sub 1}), and Mg(3s{sup 1}3d{sup 1},3 {sup 3}D{sub 3,2,1}) as well as the phosphorescent emission due to Mg(3 {sup 3}P{sub 1}) have been observed from excited Mg atoms and the charge-transfer emission decays from K(4 {sup 2}P{sub 3/2,1/2}),K(5 {sup 2}P{sub 3/2,1/2}),K(6 {sup 2}S{sub 1/2}), and K(4 {sup 2}D{sub 5/2,3/2}) for excited K atoms. The corresponding absolute cross-sections values versus collision energy functions were determined in the 0.10-3.80 keV laboratory energy range. In order to interpret the experimental results, accurate ab initio full configuration-interaction calculations using pseudopotentials have been performed for the (Mg-K){sup +} system, giving a manifold of adiabatic singlet and triplet potential-energy curves correlating with the different collision channels, which allow a qualitative interpretation of the emission excitation functions measured for the different processes studied. A comparative study with other Mg-alkali ion systems previously studied is also included.

  14. Effect of ambient Mg/Ca ratio on Mg fractionation in calcareous marine invertebrates: A record of the oceanic Mg/Ca ratio over the Phanerozoic

    NASA Astrophysics Data System (ADS)

    Ries, Justin B.

    2004-11-01

    The Mg/Ca ratio of seawater has changed significantly over the Phanerozoic, primarily as a function of the rate of ocean-crust production. Echinoids, crabs, shrimps, and calcareous serpulid worms grown in artificial seawaters encompassing the range of Mg/Ca ratios that existed throughout the Phanerozoic exhibit a direct nonlinear relationship between skeletal and ambient Mg/Ca. Specimens grown in seawater with the lowest Mg/Ca (˜1) changed their mineralogy to low-Mg calcite (<4 mol% MgCO3), suggesting that these high-Mg calcareous organisms would have produced low-Mg calcite in the Cretaceous, when oceanic Mg/Ca was lowest (˜1). These results support the empirical evidence that the skeletal chemistry of calcareous organisms has varied significantly over the Phanerozoic as a function of the Mg/Ca of seawater, and that the Mg/Ca of unaltered fossils of such organisms may be a record of oceanic Mg/Ca throughout the Phanerozoic. Mg fractionation algorithms, which relate skeletal Mg/Ca, seawater Mg/Ca, and temperature, were derived from these and other experiments. They can be used to estimate paleoceanic Mg/ Ca ratios and temperatures from fossil skeletal Mg/Ca of the organisms evaluated. Pale oceanic Mg/Ca ratios, recalculated by using the echinoderm Mg fractionation algorithm from published fossil echinoid Mg/Ca, crinoid Mg/Ca, and paleotemperature data, are consistent with other estimates and models of oceanic Mg/Ca over the Phanerozoic.

  15. Determination of the 36Mg(n ,γ )37Mg reaction rate from Coulomb dissociation of 37Mg

    NASA Astrophysics Data System (ADS)

    Shubhchintak; Chatterjee, R.; Shyam, R.

    2017-08-01

    We use the Coulomb dissociation (CD) method to calculate the rate of the 36Mg(n ,γ )37Mg radiative capture reaction. The CD cross sections of the 37Mg nucleus on a 208Pb target at the beam energy of 244 MeV/nucleon, for which new experimental data have recently become available, were calculated within the framework of a finite-range distorted-wave Born approximation theory that is extended to include the projectile deformation effects. Invoking the principle of detailed balance, these cross sections are used to determine the excitation function and subsequently the rate of the 36Mg(n ,γ )37Mg reaction. We compare these rates to those of the 36Mg(α ,n )39Si reaction calculated within a Hauser-Feshbach model. We find that for T9 as large as up to 1.0 (in units of 109 K) the 36Mg(n ,γ )37Mg reaction is much faster than the 36Mg(α ,n )39Si one. The inclusion of the effects of 37Mg projectile deformation in the breakup calculations enhances the (n ,γ ) reaction rate even further. Therefore, it is highly unlikely that the (n ,γ )β -decay r -process flow will be broken at the 36Mg isotope by the α process.

  16. Role of Mg interlayers in Fe/Mg/MgO/Fe and Fe/Mg/MgO/Mg/Fe magnetic tunnel junctions

    SciTech Connect

    Wang, Y.; Zhang, J.; Zhang, Xiaoguang; Cheng, Hai-Ping; Han, Prof. X. F.

    2010-01-01

    -Fe(001)/Mg/MgO/Fe- and -Fe(001)/Mg/MgO/Mg/Fe- magnetic tunnel junctions (MTJs) with Mg interlayers are studied by first-principles calculation. An important role of the Mg interlayer is identified to be preserving the preferential transmission of the majority-spin states with \\Delta_1 symmetry, which dominate the spin-dependent electron transport of MTJs with MgO barrier. One layer of Mg at the electrode/barrier interface does not decrease the tunneling magnetoresistance (TMR) ratio nearly as much as one layer of oxide. At certain Mg thickness case the TMR could be strongly influenced by the resonance tunneling states in minority-spin channel, these states are mainly raised from the quantum-well states formed in the Mg interlayer and coupled with interfacial resonance states which are very sensitive to the interface structures.

  17. The MG Composite

    PubMed Central

    Burns, Ted M.; Conaway, Mark; Sanders, Donald B.

    2010-01-01

    Objective: To study the concurrent and construct validity and test-retest reliability in the practice setting of an outcome measure for myasthenia gravis (MG). Methods: Eleven centers participated in the validation study of the Myasthenia Gravis Composite (MGC) scale. Patients with MG were evaluated at 2 consecutive visits. Concurrent and construct validities of the MGC were assessed by evaluating MGC scores in the context of other MG-specific outcome measures. We used numerous potential indicators of clinical improvement to assess the sensitivity and specificity of the MGC for detecting clinical improvement. Test-retest reliability was performed on patients at the University of Virginia. Results: A total of 175 patients with MG were enrolled at 11 sites from July 1, 2008, to January 31, 2009. A total of 151 patients were seen in follow-up. Total MGC scores showed excellent concurrent validity with other MG-specific scales. Analyses of sensitivities and specificities of the MGC revealed that a 3-point improvement in total MGC score was optimal for signifying clinical improvement. A 3-point improvement in the MGC also appears to represent a meaningful improvement to most patients, as indicated by improved 15-item myasthenia gravis quality of life scale (MG-QOL15) scores. The psychometric properties were no better for an individualized subscore made up of the 2 functional domains that the patient identified as most important to treat. The test-retest reliability coefficient of the MGC was 98%, with a lower 95% confidence interval of 97%, indicating excellent test-retest reliability. Conclusions: The Myasthenia Gravis Composite is a reliable and valid instrument for measuring clinical status of patients with myasthenia gravis in the practice setting and in clinical trials. PMID:20439845

  18. Microwave losses in MgO, LaAlO{sub 3}, and (La{sub 0.3}Sr{sub 0.7})(Al{sub 0.65}Ta{sub 0.35})O{sub 3} dielectrics at low power and in the millikelvin temperature range

    SciTech Connect

    Arzeo, M.; Lombardi, F.; Bauch, T.

    2014-05-26

    We have investigated both the temperature and the power dependence of microwave losses for various dielectrics commonly used as substrates for the growth of high critical temperature superconductor thin films. We present measurement of niobium superconducting λ∕2 coplanar waveguide resonators, fabricated on MgO, LaAlO{sub 3}, and (La{sub 0.3}Sr{sub 0.7})(Al{sub 0.65}Ta{sub 0.35})O{sub 3} (LSAT), at the millikelvin temperature range and at low input power. By comparing our results with the two-level system model, we have discriminated among different dominant loss mechanisms. LSAT has shown the best results as regards the dielectric losses in the investigated regimes.

  19. Passive Ranging

    DTIC Science & Technology

    1988-08-01

    1981). 5. R. Courant and D. Hilbert, Methods of Mathematical Physics , Vol. I, English ed., * Interscience, New York, 1953. 32 32 APPENDIX A CALCULATION...K Courant and D. Hilbert, Methods of Mathematical Physics , Vol. I, English ed., * Interscience, New York, 1953. A-8 APPENDIX B * RANGING ACCURACY IN

  20. Fe-Mg Interdiffusion in (Mg,Fe)O

    NASA Astrophysics Data System (ADS)

    Mackwell, Stephen; Bystricky, Misha; Sproni, Caroline

    2005-09-01

    We have performed a series of interdiffusion experiments on magnesiowüstite samples at room pressure, temperatures from 1,320° to 1,400°C, and oxygen fugacities from 10-1.0 Pa to 10-4.3 Pa, using mixed CO/CO2 or H2/CO2 gases. The interdiffusion couples were composed of a single-crystal of MgO lightly pressed against a single-crystal of (Mg1- x Fe x )1-δO with 0.07< x<0.27. The interdiffusion coefficient was calculated using the Boltzmann-Matano analysis as a function of iron content, oxygen fugacity, temperature, and water fugacity. For the entire range of conditions tested and for compositions with 0.01< x<0.27, the interdiffusion coefficient varies as tilde D = 2.9×10^{ - 6} f_{{text{O}}_2 }^{0.19} x^{0.73} {text{e}}^{ - (209,000 - 96,000 x)/RT} {text{m}}^{text{2}} {text{s}}^{ -1} These dependencies on oxygen fugacity and composition are reasonably consistent with interdiffusion mediated by unassociated cation vacancies. For the limited range of water activity that could be investigated using mixed gases at room pressure, no effect of water on interdiffusion could be observed. The dependence of the interdiffusion coefficient on iron content decreased with increasing iron concentration at constant oxygen fugacity and temperature. There is a close agreement between our activation energy for interdiffusion extrapolated to zero iron content ( x=0) and that of previous researchers who used electrical conductivity experiments to determine vacancy diffusivities in lightly doped MgO.

  1. Mg Isotopic Compositions of Modern Marine Carbonates

    NASA Astrophysics Data System (ADS)

    Krogstad, E.; Bizzarro, M.; Hemming, N.

    2003-12-01

    We have used a MC-ICP-MS to measure the isotopic composition of magnesium in a number of samples of modern marine carbonate. Due to the large mass difference between 26Mg and 24Mg (similar to that between 13C and 12C), there is potential for mass fractionation during geologic and biologic processes that may make this isotope system useful for geochemical studies. These samples are from the study of Hemming and Hanson (1992, GCA 56: 537-543). The carbonate minerals analyzed include aragonite, low-Mg calcite, and high-Mg calcite. The samples include corals, echinoderms, ooids, etc., from subtropical to Antarctic settings. Mg purification was accomplished by ion-exchange chromatography, using Bio-Rad AG50W-X12 resin on which greater than 99 percent recovery of Mg is achieved. Samples were introduced into the MC-ICP-MS (VG Axiom) using a Cetac MCN-6000 nebuliser. We use a standard-sample-standard bracketing technique, and samples are analysed at least three times. For lab standards we find that the reproducibility on the 26Mg/24Mg to be about ñ 0.12 permil (2 s.d.). We monitored our separated samples for Na and Ca, as we have found that high Ca/Mg and Na/Mg produce variable magnesium isotopic fractionation during mass spectrometry due to as yet unclear matrix effects. We have normalized our results to our measured values for seawater. We observed a d26Mg(s.w.) range of -1.4 to -2.4 permil in our modern carbonate samples relative to present day seawater. Due to the long residence time of Mg in the oceans (ca. 50 my), this must be due to kinetic or biologic effects. Our d25Mg(s.w.) variations as a function of d26Mg(s.w.) plot along the terrestrial fractionation trend. With an average d26Mg(s.w.) of ca. +0.5 permil in all samples of mantle lithologies and mantle-derived igneous rocks (Bizzarro et al., Goldschmidt abs., 2003), we can assume that the Mg isotopic composition of Earth's river water lies between ca. -2.4 and +0.5 permil (relative to seawater). The actual

  2. Long range B-site cation ordering and Briet–Wigner–Fano line shape of A{sub 1g}-like Raman mode in Nd{sub 1−x}Sm{sub x}(Mg{sub 0.5}Ti{sub 0.5})O{sub 3} microwave dielectric ceramics

    SciTech Connect

    Kiran, S. Roopas; Babu, G. Santosh; Narayana, Chandrabhas; Murthy, V.R.K.; Subramanian, V.

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Q × f of Nd{sub 1–x}Sm{sub x}(Mg{sub 0.5}Ti{sub 0.5})O{sub 3} are correlated with B-site cation ordering (LRO). ► Correlation between LRO and Γ of A{sub 1g}-like mode in Raman spectrum is observed. ► Reason for asymmetry in A{sub 1g}-like Raman mode in these materials is revealed. ► Briet–Wigner–Fano resonance is confirmed with temperature variation in Raman spectra. -- Abstract: Nd{sub 1−x}Sm{sub x}(Mg{sub 0.5}Ti{sub 0.5})O{sub 3} (x = 0.0–1.0) samples were prepared by solid-state reaction method. Rietveld refinement of X-ray diffraction data was done using P2{sub 1}/n space group with monoclinic symmetry, which supports 1:1 B-site cation ordering. Long range ordering (LRO) parameter decreased up to x = 0.5 and then found to increase with further increase in Sm concentration. The A{sub 1g}-like mode in Raman spectra was observed to possess Briet–Wigner–Fano line shape. The variation in obtained line width of the A{sub 1g}-like mode supported LRO. Microwave dielectric characteristics such as dielectric constant (ε{sub r}), quality factor (Q) and temperature coefficient of resonant frequency (τ{sub f}) were measured in the range of 7–9 GHz. ε{sub r} decreased from 26.5 to 24.9 and τ{sub f} become less negative from −58 ppm/°C to −36 ppm/°C with increase in Sm concentration. Q × f decreased from 47,500 GHz (for x = 0) to 39,800 GHz (for x = 0.5) and then increased to 44,600 GHz (for x = 1).

  3. Range and range rate system

    NASA Technical Reports Server (NTRS)

    Graham, Olin L. (Inventor); Russell, Jim K. (Inventor); Epperly, Walter L. (Inventor)

    1988-01-01

    A video controlled solid state range finding system which requires no radar, high power laser, or sophisticated laser target is disclosed. The effective range of the system is from 1 to about 200 ft. The system includes an opto-electric camera such as a lens CCD array device. A helium neon laser produces a source beam of coherent light which is applied to a beam splitter. The beam splitter applies a reference beam to the camera and produces an outgoing beam applied to a first angularly variable reflector which directs the outgoing beam to the distant object. An incoming beam is reflected from the object to a second angularly variable reflector which reflects the incoming beam to the opto-electric camera via the beam splitter. The first reflector and the second reflector are configured so that the distance travelled by the outgoing beam from the beam splitter and the first reflector is the same as the distance travelled by the incoming beam from the second reflector to the beam splitter. The reference beam produces a reference signal in the geometric center of the camera. The incoming beam produces an object signal at the camera.

  4. Phase equilibrium in Mg-Cu-Y

    NASA Astrophysics Data System (ADS)

    Mezbahul-Islam, Mohammad; Medraj, Mamoun

    2013-10-01

    Magnesium-based bulk metallic glasses (BMG) have potential in applications ranging from biomedical to sports equipment and the Mg-Cu-Y system offers some of the most promising alloys. Phase relations and ternary solubility of the binary and ternary compounds of this system have been experimentally investigated. The Isothermal section of Mg-Cu-Y system at 673 K for the entire composition range has been constructed. Phase relations in the Cu-rich (>66 at.% Cu) region of the Mg-Cu-Y system has been determined for the first time. The homogeneity range of three ternary compounds has been determined. Solidifications behavior of several key alloys have been discussed based on the differential scanning calorimetry (DSC) experiments and thermodynamic calculations. Extensive analysis of the DSC curves has been carried out to relate them to the corresponding phase transformation reactions and temperatures. Some of the most promising metallic glass forming regions have been analyzed using thermodynamic calculations.

  5. The effect of the MgO buffer layer thickness on magnetic anisotropy in MgO/Fe/Cr/MgO buffer/MgO(001)

    SciTech Connect

    Kozioł-Rachwał, Anna; Nozaki, Takayuki; Zayets, Vadym; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji; Suzuki, Yoshishige

    2016-08-28

    The relationship between the magnetic properties and MgO buffer layer thickness d was studied in epitaxial MgO/Fe(t)/Cr/MgO(d) layers grown on MgO(001) substrate in which the Fe thickness t ranged from 0.4 nm to 1.1 nm. For 0.4 nm ≤ t ≤ 0.7 nm, a non-monotonic coercivity dependence on the MgO buffer thickness was shown by perpendicular magneto-optic Kerr effect magnetometry. For thicker Fe films, an increase in the buffer layer thickness resulted in a spin reorientation transition from perpendicular to the in-plane magnetization direction. Possible origins of these unusual behaviors were discussed in terms of the suppression of carbon contamination at the Fe surface and changes in the magnetoelastic anisotropy in the system. These results illustrate a method to control magnetic anisotropy in MgO/Fe/Cr/MgO(d) via an appropriate choice of MgO buffer layer thickness d.

  6. Melting relations in the MgO-MgSiO3 system up to 70 GPa

    NASA Astrophysics Data System (ADS)

    Ohnishi, Satoka; Kuwayama, Yasuhiro; Inoue, Toru

    2017-06-01

    Melting experiments in a binary system MgO-MgSiO3 were performed up to 70 GPa using a CO2 laser heated diamond anvil cell. The quenched samples were polished and analyzed by a dualbeam focused ion beam (FIB) and a field emission scanning electron microscope (FE-SEM), respectively. The liquidus phase and the eutectic composition were determined on the basis of textual and chemical analyses of sample cross sections. Our experimental results show that the eutectic composition is the Si/Mg molar ratio of 0.76 at 35 GPa and it decreases with increasing pressure. Above 45 GPa, it becomes relatively constant at about 0.64-0.65 Si/Mg molar ratio. Using our experimental data collected at a wide pressure range up to 70 GPa together with previous experimental data, we have constructed a thermodynamic model of the eutectic composition of the MgO-MgSiO3 system. The eutectic composition extrapolated to the pressure and temperature conditions at the base of the mantle is about 0.64 Si/Mg molar ratio. The modeled eutectic composition is quite consistent with a previous prediction from ab initio calculations (de Koker et al. in Earth Planet Sci Lett 361:58-63, 2013), suggesting that the simple assumption of a non-ideal regular solution model can well describe the melting relation of the MgO-MgSiO3 system at high pressure. Our results show that the liquidus phase changes from MgO-periclase to MgSiO3-bridgmanite at 35 GPa for the simplified pyrolite composition ( 0.7 Si/Mg molar ratio), while MgSiO3-bridgmanite is the liquidus phase at the entire lower mantle conditions for the chondritic composition ( 0.84 Si/Mg molar ratio).

  7. Melting relations in the MgO-MgSiO3 system up to 70 GPa

    NASA Astrophysics Data System (ADS)

    Ohnishi, Satoka; Kuwayama, Yasuhiro; Inoue, Toru

    2017-02-01

    Melting experiments in a binary system MgO-MgSiO3 were performed up to 70 GPa using a CO2 laser heated diamond anvil cell. The quenched samples were polished and analyzed by a dualbeam focused ion beam (FIB) and a field emission scanning electron microscope (FE-SEM), respectively. The liquidus phase and the eutectic composition were determined on the basis of textual and chemical analyses of sample cross sections. Our experimental results show that the eutectic composition is the Si/Mg molar ratio of 0.76 at 35 GPa and it decreases with increasing pressure. Above 45 GPa, it becomes relatively constant at about 0.64-0.65 Si/Mg molar ratio. Using our experimental data collected at a wide pressure range up to 70 GPa together with previous experimental data, we have constructed a thermodynamic model of the eutectic composition of the MgO-MgSiO3 system. The eutectic composition extrapolated to the pressure and temperature conditions at the base of the mantle is about 0.64 Si/Mg molar ratio. The modeled eutectic composition is quite consistent with a previous prediction from ab initio calculations (de Koker et al. in Earth Planet Sci Lett 361:58-63, 2013), suggesting that the simple assumption of a non-ideal regular solution model can well describe the melting relation of the MgO-MgSiO3 system at high pressure. Our results show that the liquidus phase changes from MgO-periclase to MgSiO3-bridgmanite at 35 GPa for the simplified pyrolite composition ( 0.7 Si/Mg molar ratio), while MgSiO3-bridgmanite is the liquidus phase at the entire lower mantle conditions for the chondritic composition ( 0.84 Si/Mg molar ratio).

  8. Application of calcite Mg partitioning functions to the reconstruction of paleocean Mg/Ca

    NASA Astrophysics Data System (ADS)

    Hasiuk, Franciszek J.; Lohmann, Kyger C.

    2010-12-01

    Calcite Mg/Ca is usually assumed to vary linearly with solution Mg/Ca, that a constant partition coefficient describes the relationship between these two ratios. Numerous published empirical datasets suggests that this relationship is better described by a power function. We provide a compilation of these literature data for biotic and abiotic calcite in the form of Calcite Mg/Ca = F(Solution Mg/Ca) H, where F and H are empirically determined fitting parameters describing the slope and deviation from linearity, respectively, of the function. This is equivalent to Freundlich sorption behavior controlling Mg incorporation in calcite. Using a power function, instead of a partition coefficient, lowers Phanerozoic seawater Mg/Ca estimates based on echinoderm skeletal material by, on average, 0.5 mol/mol from previous estimates. These functions can also be used to model the primary skeletal calcite Mg/Ca of numerous calcite phases through geologic time. Such modeling suggests that the Mg/Ca of all calcite precipitated from seawater has varied through the Phanerozoic in response to changing seawater Mg/Ca and that the overall range in Mg/Ca measured among various calcite phases would be greatest when seawater Mg/Ca was also high (e.g., "aragonite seas") and lowest when seawater Mg/Ca was low (e.g., "calcite seas"). It follows that, during times of "calcite seas" when the seawater Mg/Ca is presumed to have been lower, deposition of calcite with low Mg contents would have resulted in a depressed drive for diagenetic stabilization of shelfal carbonate and, in turn, lead to greater preservation of crystal and skeletal microfabrics and primary chemistries in biotic and abiotic calcites.

  9. UHV and Ambient Pressure XPS: Potentials for Mg, MgO, and Mg(OH)2 Surface Analysis

    NASA Astrophysics Data System (ADS)

    Head, Ashley R.; Schnadt, Joachim

    2016-12-01

    The surface sensitivity of x-ray photoelectron spectroscopy (XPS) has positioned the technique as a routine analysis tool for chemical and electronic structure information. Samples ranging from ideal model systems to industrial materials can be analyzed. Instrumentational developments in the past two decades have popularized ambient pressure XPS, with pressures in the tens of mbar now commonplace. Here, we briefly review the technique, including a discussion of developments that allow data collection at higher pressures. We illustrate the information XPS can provide by using examples from the literature, including MgO studies. We hope to illustrate the possibilities of ambient pressure XPS to Mg, MgO, and Mg(OH)2 systems, both in fundamental and applied studies.

  10. Diffusion of Ca and Mg in Calcite

    SciTech Connect

    Cygan, R.T.; Fisler, D.K.

    1999-02-10

    The self-diffusion of Ca and the tracer diffusion of Mg in calcite have been experimentally measured using isotopic tracers of {sup 25}Mg and {sup 44}Ca. Natural single crystals of calcite were coated with a thermally-sputtered oxide thin film and then annealed in a CO{sub 2} gas at one atmosphere total pressure and temperatures from 550 to 800 C. Diffusion coefficient values were derived from the depth profiles obtained by ion microprobe analysis. The resultant activation energies for Mg tracer diffusion and Ca self-diffusion are respectively: E{sub a}(Mg) = 284 {+-} 74 kJ/mol and E{sub a}(Ca) = 271 {+-} 80 kJ/mol. For the temperature ranges in these experiments, the diffusion of Mg is faster than Ca. The results are generally consistent in magnitude with divalent cation diffusion rates obtained in previous studies and provide a means of interpreting the thermal histories of carbonate minerals, the mechanism of dolomitization, and other diffusion-controlled processes. The results indicate that cation diffusion in calcite is relatively slow and cations are the rate-limiting diffusing species for the deformation of calcite and carbonate rocks. Application of the calcite-dolomite geothermometer to metamorphic assemblages will be constrained by cation diffusion and cooling rates. The direct measurement of Mg tracer diffusion in calcite indicates that dolomitization is unlikely to be accomplished by Mg diffusion in the solid state but by a recrystallization process.

  11. Mg/Ca of Continental Ostracode Shells

    NASA Astrophysics Data System (ADS)

    Ito, E.; Forester, R. M.; Marco-Barba, J.; Mezquita, F.

    2007-12-01

    Marine ionic chemistry is thought to remain constant. This, together with the belief that marine calcifiers partition Mg/Ca in a systematic manner as functions of temperature (and Mg/Ca) of water forms the basis of the Mg/Ca thermometer. In continental settings both of these assumptions are usually not true. Continental waters contain a wide variety of solutes in absolute and relative ion concentrations. Hence, waters with identical Mg/Ca may have very different concentrations of Mg and Ca and very different anions. Here we use two examples to focus on the effects of ion chemistry on Mg/Ca partitioning in continental ostracode shells and we ignore the complexities of solute evolution, which can change Mg/Ca over timescales of minutes to millennia. Palacios-Fest and Dettman (2001) conducted a monthly study of ,Cypridopsis vidua at El Yeso Lake in Sonora, Mexico. They established a relation between temperature and average shell Mg/Ca using regression analyses on averaged data. When their Mg/Ca-temperature relation is applied to monthly ,C. vidua data from Page Pond near Cleveland, Ohio, water temperatures of -8 to -1°C are obtained. The observed Mg/Ca ranges for El Yeso Lake (0.31 to 0.46) and Page Pond (0.33 to 0.46) are similar, as are their specific conductivities (700 to 850μS for El Yeso Lake; 400 to 600μS for Page Pond). However, [Ca] is 140-260 mg/L for El Yeso, but only 70-90 mg/L for Page Pond. Page Pond data, in fact, shows a good temperature shell Mg/Ca relation for .C. vidua, but the relation is different from that at El Yeso. Hence, shell Mg/Ca is a multi-valued, family of curves function of temperature and Mg/Ca of water that depends on the [Mg] and [Ca] values in water and perhaps other factors. Our second example comes from sites near Valencia, Spain and involves shell data for ,Cyprideis torosa, an estuarine ostracode that is tolerant of a wide range of salinity and can live in continental waters as long as the carbonate alkalinity to Ca ratio is

  12. Treatment for Myasthenia Gravis (MG)

    MedlinePlus

    ... the plasma of the blood. The improvement in muscle strength may be striking, but is usually short-lived, ... MG, most patients will have improvement in their muscle strength. In some cases MG may go into remission ...

  13. Mg(+)-ligand binding energies

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry

    1991-01-01

    Ab initio calculations are used to optimize the structures and determine the binding energies of Mg(+) to a series of ligands. Mg(+) bonds electrostatically with benzene, acetone, H2, CO, and NH3 and a self-consistent-field treatment gives a good description of the bonding. The bonding in MgCN(+) and MgCH3(+) is largely covalent and a correlated treatment is required.

  14. Thermodynamic properties of liquid Mg-ln-Cd ternary solutions

    NASA Astrophysics Data System (ADS)

    Moser, Z.; Gasior, W.; Panek, Z.

    1984-09-01

    By means of concentration cells of the following type: Mg(s)∣MgCl2 in (LiCl-KCl)eut( l)∣Mg-In or Mg-ln-Cd( l), the partial thermodynamic data of Mg in Mg-ln and Mg-ln-Cd liquid solutions have been obtained in the composition range 0.1 ≤ XMg ≤ 0.7 for binary while for ternary alloys for t = 0.4, 0.6, and 0.8 (where t = XIn/(XIn + XCd)) and at various mangesium concentrations 0.1≤ XMg ≤ 0.6. Both ternary and binary alloys were investigated at a temperature range 750 to 900 K. Experimental partial excess Gibbs energies of Mg were interpreted by the Pelton and Flengas method. Results for Mg-ln system show a slight difference in comparison with previously published data for the same system also from emf studies. Results of this study for Mg-ln system exhibit negative and positive excess entropies of magnesium and the same is observed in ternary system Mg-ln-Cd at the range of concentration close to Mg-ln.

  15. On the structure of 30Mg and 32Mg

    NASA Astrophysics Data System (ADS)

    Macchiavelli, A. O.; Crawford, H. L.

    2017-06-01

    We discuss a phenomenological picture consisting of two- and three-level mixing models to describe the low-lying 0+ states in 30Mg and 32Mg, respectively. Within this approach, self-consistent solutions exist that are in good agreement with the available experimental information. The inclusion of a third state, namely the neutrons 4p4h configuration, resolves the ‘puzzle’ that results from a two-level model interpretation of the 30Mg(t, p)32Mg reaction data, and at the same time provides a consistent interpretation of B(E2) strengths. Our analysis indicates a 30Mg ground-state dominated by the spherical (0p0h) component while 32Mg emerges naturally and robustly as dominated by deformed (2p2h and 4p4h configurations), at the 95% level.

  16. The 30Mg(t ,p )32Mg "puzzle" reexamined

    NASA Astrophysics Data System (ADS)

    Macchiavelli, A. O.; Crawford, H. L.; Campbell, C. M.; Clark, R. M.; Cromaz, M.; Fallon, P.; Jones, M. D.; Lee, I. Y.; Salathe, M.; Brown, B. A.; Poves, A.

    2016-11-01

    Background: Competing interpretations of the results of a 30Mg(t ,p )32Mg measurement populating the ground state and 02+ state in 32Mg, both limited to a two-state mixing description, have left an open question regarding the nature of the 32Mg ground state. Purpose: Inspired by recent shell-model calculations, we explore the possibility of a consistent interpretation of the available data for the low-lying 0+ states in 32Mg by expanding the description from two-level to three-level mixing. Methods: A phenomenological three-level mixing model of unperturbed 0p0h, 2p2h, and 4p4h states is applied to describe both the excitation energies in 32Mg and the transfer reaction cross sections. Results: Within this approach, self-consistent solutions exist that provide good agreement with the available experimental information obtained from the 30Mg(t ,p )32Mg reaction. Conclusion: The inclusion of the third state, namely the 4p4h configuration, resolves the "puzzle" that results from a two-levelmodel interpretation of the same data. In our analysis, the 32Mg ground state emerges naturally as dominated by intruder (2p2h and 4p4h) configurations, at the 95% level.

  17. Energy band bowing parameter in MgZnO alloys

    SciTech Connect

    Wang, Xu; Saito, Katsuhiko; Tanaka, Tooru; Nishio, Mitsuhiro; Guo, Qixin; Nagaoka, Takashi; Arita, Makoto

    2015-07-13

    We report on bandgap bowing parameters for wurtzite and cubic MgZnO alloys from a study of high quality and single phase films in all Mg content range. The Mg contents in the MgZnO films were accurately determined using the energy dispersive spectrometer and X-ray photoelectron spectroscopy (XPS). The measurement of bandgap energies by examining the onset of inelastic energy loss in core-level atomic spectra from XPS is proved to be valid for determining the bandgap of MgZnO films. The dependence of the energy bandgap on Mg content is found to deviate downwards from linearity. Fitting of the bandgap data resulted in two bowing parameters of 2.01 ± 0.04 eV and 1.48 ± 0.11 eV corresponding to wurtzite and cubic MgZnO films, respectively.

  18. Comparative effects of a Mg-enriched diet and different orally administered magnesium oxide preparations on ionized Mg, Mg metabolism and electrolytes in serum of human volunteers.

    PubMed

    Altura, B T; Wilimzig, C; Trnovec, T; Nyulassy, S; Altura, B M

    1994-10-01

    To determine whether: 1) short-term dietary elevation in magnesium (Mg) intake could alter serum ionized Mg (IMg2+), total Mg (TMg); % ionized Mg (% IMg2+) and other cations; and 2) different formulated preparations of Mg oxide (MgO) in the presence and absence of phosphate could alter serum IMg2+, TMg, % IMg2+ and other cations in Mg-loaded subjects. A randomized, triple cross-over study was performed on a rigorously defined group of normal male volunteers. Eighteen males were administered diets containing four to five times the United States recommended daily allowance (USRDA) of Mg followed by a randomization of three different MgO preparations, in the presence or absence of phosphate, containing equimolar amounts (12.34 mmol) of elemental Mg. Forty age-matched volunteers served as reference range controls. Specific ion selective electrodes were utilized to measure IMg2+, ionized calcium (ICa2+), sodium (Na+) potassium (K+) and hydrogen ion concentration (H+). Measurement of urinary excretion of Mg as well as TMg were determined by atomic absorption spectroscopy. Diets enriched with different oral formulations of Mg given for 6 days result in significant elevations in serum IMg2+ and % IMg2+ but not TMg, ICa2+, K+ or H+ in normal subjects. Although such Mg-loaded subjects demonstrate significant elevation in urinary excretion of Mg, no further changes in IMg2+, TMg or any of the serum cations were produced by ingestion of either of the three MgO preparations. Subjects showing normally low basal levels of serum IMg2+, (< or = 0.54 mM/L), could easily have their serum IMg2+ level manipulated by diets enriched with Mg, whereas subjects having average normal or high normal IMg2+ levels did not have their IMg2+ elevated significantly with either diets enriched with Mg or with exogenous MgO. These results indicate that since serum IMg2+ and % IMg2+, but not TMg, can be altered by dietary intake, previous or future findings which may indicate no change in TMg by diet

  19. Thermodynamic data of Mg-chloritoid

    NASA Astrophysics Data System (ADS)

    Grevel, K.-D.; Navrotsky, A.; Kahl, W.-A.; Majzlan, J.; Lathe, C.

    2003-04-01

    Calorimetric and P-V-T data for synthetic Mg-chloritoid (MgAl2SiO5(OH)2) have been obtained. The enthalpy of drop-solution was measured by high-temperature oxide melt calorimetry in two laboratories (UC Davis, California, and Ruhr-University Bochum, Germany) using lead borate (2 PbO\\cdotB2O3) at T = 700 oC as solvent. The resulting values were used to calculate the enthalpy of formation from the elements; they range from -3552.7 ± 4.9 kJ mol-1 to -3555.4±6.1 kJ mol-1. Some preliminary heat capacity measurements of MgAl2SiO5(OH)2 have shown that a Berman and Brown (1985) type four-term equation based on the Neumann-Kopp rule represents the heat capacity over the entire temperature range to within the experimental uncertainty. The P-V-T behaviour of Mg-chloritoid has been determined under high pressures and high temperatures up to 8.5 GPa and 800 oC using a MAX 80 cubic anvil high-pressure apparatus. The samples were mixed with vaseline to ensure hydrostatic pressure transmitting conditions, NaCl served as an internal standard for pressure calibration. By fitting a Birch-Murnaghan EOS to the data, the bulk modulus was determined as 131.0 ± 2.4 GPa, (K' = 4), VT,0 = 456.58 Å3 exp [int(0.30±0.02) × 10-4 dT], (partialKT/partialT)P = -0.023±0.007 GPa K-1. The thermodynamic data obtained for Mg-chloritoid are consistent with phase equilibrium data reported in the literature. The best agreement was obtained with ΔfH0298 (Mg-chloritoid) = -3557.5 kJ mol-1, and S0298 (Mg-chloritoid) = 131.7 J K-1mol-1.

  20. Decay branching ratios of excited 24Mg

    NASA Astrophysics Data System (ADS)

    Munson, J. M.; Norman, E. B.; Burke, J. T.; Casperson, R. J.; Phair, L. W.; McCleskey, E.; McCleskey, M.; Lee, D.; Hughes, R. O.; Ota, S.; Czeszumska, A.; Chodash, P. A.; Saastamoinen, A. J.; Austin, R. A. E.; Spiridon, A. E.; Dag, M.; Chyzh, R.; Basunia, M. S.; Ressler, J. J.; Ross, T. J.

    2017-01-01

    The nuclear reactions 12C(12C,α )20Ne , 12C(12C,p )23Na , and 12C(12C,n )23Mg are the primary reactions in carbon burning, which occurs as part of several stellar processes. The Gamow window, which describes the energy range where most of these reactions take place, is typically around 1.5 MeV in the center-of-mass frame. Direct measurements of the cross sections at this energy are difficult due to the large Coulomb barrier present between the carbon nuclei; however, a successful surrogate measurement can provide the branching ratios between these reactions while avoiding the 12C+12C Coulomb barrier. An experiment was performed using inelastic scattering of 40 MeV α particles on 24Mg as a possible surrogate for the 12C+12C compound nucleus.

  1. Quasicrystal-reinforced Mg alloys

    PubMed Central

    Kyun Kim, Young; Tae Kim, Won; Hyang Kim, Do

    2014-01-01

    The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg–Zn–Y and Mg–Zn–Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α-Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg–Zn–Y alloys, the co-presence of I and Ca2Mg6Zn3 phases by addition of Ca can significantly enhance formability, while in Mg–Zn–Al alloys, the co-presence of the I-phase and Mg2Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg–Zn–Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg–Zn–Al–Sn alloys is attributed to the presence of finely distributed Mg2Sn and I-phase particles embedded in the α-Mg matrix. PMID:27877660

  2. Atomic structure of biodegradable Mg-based bulk metallic glass.

    PubMed

    Christie, J K

    2015-05-21

    We have used highly accurate first-principles molecular dynamics simulations to elucidate the structure of Mg60Zn35Ca5 and Mg72Zn23Ca5 bulk metallic glasses, which are candidate materials for biomedical implants; these two compositions exhibit different behaviours when implanted. The environments of each species are different, and average coordination numbers are ∼13 for Mg, ∼11 for Zn and ∼18-19 for Ca. A wide range of local environments were found and icosahedral motifs, often seen in bulk metallic glasses, were among the most common for both Mg and Zn. Through the computation of a chemical short-range order parameter, a moderate avoidance of Zn-Zn bonding over Zn-Mg or Zn-Ca was observed. No statistically significant difference in structure was observed between the two compositions.

  3. Progress in Thermodynamic Database Development for ICME of Mg Alloys

    NASA Astrophysics Data System (ADS)

    Schmid-Fetzer, Rainer

    Integrated thermodynamic software packages are a powerful tool to analyze phase formation in multicomponent Mg alloys, providing key data for focused alloy and process development. The thermodynamic database of the alloy system is the indispensable basis for this direct application, but also needed for any further step towards Integrated Computational Materials Engineering. The database quality, which may vary widely, is crucial for the reliability of such applications. Progress in development and extension of the large thermodynamic database for magnesium alloys is reported, with emphasis on consistency, coherency and quality assurance. One aspect is the coherent description of large solid solution ranges of intermetallic phases in multicomponent Mg alloys with rare earths. Further addition of Zn may produce complex icosahedral, long-period stacking order (LPSO) or other hexagonal phases. All these may form highly efficient secondary phase precipitates in the (Mg) matrix. Examples are given for Mg-Ce-La, Mg-Ce-Y, and Mg-Gd-Nd-Y-Zn-Zr alloys.

  4. Electron microscopy of Mg/TiO{sub 2} photocatalyst morphology for deep desulfurization of diesel

    SciTech Connect

    Yin, Yee Cia; Kait, Chong Fai Fatimah, Hayyiratul Wilfred, Cecilia

    2015-07-22

    A series of Mg/TiO{sub 2} photocatalysts were prepared and characterized using Field Emission Scanning Electron Microscopy (FESEM) and High-Resolution Transmission Electron Microscopy (HRTEM). The average particle sizes of the photocatalysts were ranging from 25.7 to 35.8 nm. Incorporation of Mg on TiO{sub 2} did not lead to any surface lattice distortion to TiO{sub 2}. HRTEM data indicated the presence of MgO and Mg(OH){sub 2} mixture at low Mg loading while at higher Mg loading, the presence of lamellar Mg-oxyhydroxide intermediates and Mg(OH){sub 2}.

  5. Subdivision of the Mg-suite noritic rocks into Mg-gabbronorites and Mg-norites

    NASA Technical Reports Server (NTRS)

    James, O. B.; Flohr, M. K.

    1983-01-01

    Mg-suite noritic rocks can be divided into two groups, the Mg-gabbronorites and the Mg-norites. The rocks of these groups differ in ratios of high-Ca pyroxene to total pyroxene, compositions of pyroxene and plagioclase, assemblages of Ti-, Nb-, and Zr-bearing minerals, compositions of chrome spinel, bulk-rock Ti/Sm and Sc/Sm, and measured ages. The two groups probably crystallized from different types of parent magmas. Two hypotheses are offered for the differences in composition of the parent magmas. One hypothesis ascribes the differences to compositional heterogeneity of the mantle source areas. The other hypothesis ascribes the differences to variations in extent of partial melting of the mantle source regions and variations in extent of assimilation of the anorthosite and the highly differentiated residual liquid that were produced during the primordial lunar differentiation.

  6. Interstitial Fe in MgO

    SciTech Connect

    Mølholt, T. E. Gislason, H. P.; Ólafsson, S.; Mantovan, R.; Gunnlaugsson, H. P.; Svane, A.; Weyer, G.; Masenda, H.; Naidoo, D.; Bharuth-Ram, K.; Fanciulli, M.; Johnston, K.; Sielemann, R.

    2014-01-14

    Isolated {sup 57}Fe atoms were studied in MgO single-crystals by emission Mössbauer spectroscopy following implantation of {sup 57}Mn decaying to {sup 57}Fe. Four Mössbauer spectral components were found corresponding to different Fe lattice positions and/or charge states. Two components represent Fe atoms substituting Mg as Fe{sup 2+} and Fe{sup 3+}, respectively; a third component is due to Fe in a strongly implantation-induced disturbed region. The fourth component, which is the focus of this paper, can be assigned to Fe at an interstitial site. Comparison of its measured isomer shift with ab initio calculations suggests that the interstitial Fe is located on, or close to, the face of the rock-salt MgO structure. To harmonize such an assignment with the measured near-zero quadrupole interaction a local motion process (cage motion) of the Fe has to be stipulated. The relation of such a local motion as a starting point for long range diffusion is discussed.

  7. Mg/Ti multilayers: Structural and hydrogen absorption properties

    NASA Astrophysics Data System (ADS)

    Baldi, A.; Pálsson, G. K.; Gonzalez-Silveira, M.; Schreuders, H.; Slaman, M.; Rector, J. H.; Krishnan, G.; Kooi, B. J.; Walker, G. S.; Fay, M. W.; Hjörvarsson, B.; Wijngaarden, R. J.; Dam, B.; Griessen, R.

    2010-06-01

    Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a “spinodal-like” microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti multilayers with different periodicities. Notwithstanding the large lattice mismatch between Mg and Ti, the as-deposited metallic multilayers show good structural coherence. On exposure to H2 gas a two-step hydrogenation process occurs with the Ti layers forming the hydride before Mg. From in situ measurements of the bilayer thickness Λ at different hydrogen pressures, we observe large out-of-plane expansions of Mg and Ti layers on hydrogenation, indicating strong plastic deformations in the films and a consequent shortening of the coherence length. On unloading at room temperature in air, hydrogen atoms remain trapped in the Ti layers due to kinetic constraints. Such loading/unloading sequence can be explained in terms of the different thermodynamic properties of hydrogen in Mg and Ti, as shown by diffusion calculations on a model multilayered systems. Absorption isotherms measured by hydrogenography can be interpreted as a result of the elastic clamping arising from strongly bonded Mg/Pd and broken Mg/Ti interfaces.

  8. Mg impurity in helium droplets

    NASA Astrophysics Data System (ADS)

    Navarro, J.; Mateo, D.; Barranco, M.; Sarsa, A.

    2012-02-01

    Within the diffusion Monte Carlo approach, we have determined the structure of isotopically pure and mixed helium droplets doped with one magnesium atom. For pure 4He clusters, our results confirm those of Mella et al. [J. Chem. Phys. 123, 054328 (2005), 10.1063/1.1982787] that the impurity experiences a transition from a surface to a bulk location as the number of helium atoms in the droplet increases. Contrarily, for pure 3He clusters Mg resides in the bulk of the droplet due to the smaller surface tension of this isotope. Results for mixed droplets are presented. We have also obtained the absorption spectrum of Mg around the 3s3p 1P1 ← 3s2 1S0 transition.

  9. Experimental calibration of Mg isotope fractionation between aragonite and seawater

    NASA Astrophysics Data System (ADS)

    Wang, Zhengrong; Hu, Ping; Gaetani, Glenn; Liu, Chao; Saenger, Casey; Cohen, Anne; Hart, Stanley

    2013-02-01

    The detectable magnesium (Mg) isotope fractionation between biogenic aragonite (including aragonitic corals, bivalves, scaphopod, and sclerosponges) and seawater can potentially be applied to reconstruct sea surface temperature (SST) in the past. To calibrate this thermometer, eight sets of inorganic precipitation experiments ('free-drift') in seawater (Mg/Ca = 5 or 10) have been carried out at 25-55 °C over a range of degassing rate. A cleaning procedure was adopted to remove Mg contamination by sea salt, surface absorbed Mg and silicate dust as nucleation centers. The Mg isotope fractionation between cleaned aragonite and seawater-like aqueous solution varies insignificantly with Mg/Ca ratios and Mg isotope compositions of the initial solution, and the CO2-degassing rate (0-75 cc/min), but decreases noticeably with increasing temperatures having a temperature sensitivity of ˜0.008-0.01‰/°C in the following form: Δ≈1000lnα=1.67(±0.36)-0.82(±0.11)×{1000}/{T} where αaragonite-seawater is the fractionation factor, and T is the absolute temperature in Kelvin. It is consistent with equilibrium fractionation between Mg2+ aquo-complex and magnesite predicted by one theoretical calculation. Qualitative comparison among Mg-bearing carbonates based on Mg-O bond strengths show the relative sequence of 26Mg enrichment is aragonite > dolomite > magnesite > calcite. Thus, the surprising agreement indicates either the calculation overestimated Mg fractionation between magnesite and fluid, or both theoretical calculation and our calibration represent Mg isotope fractionation between MgCO30-H2O cluster and Mg2+ aquo complexes. Comparison of our calibration with the Mg isotope fractionation between biogenic aragonite and seawater suggests Mg and oxygen isotope fractionations of some biogenic aragonites (e.g., Porites sp. corals) agree with our calibration within analytical uncertainty, whereas others deviate significantly, indicating biological and/or kinetic isotope

  10. Interdiffusion and Intrinsic Diffusion in the Mg-Al System

    SciTech Connect

    Brennan, Sarah; Bermudez, Katrina; Sohn, Yong Ho; Kulkarni, Nagraj S

    2012-01-01

    Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al

  11. 108 Range Commanders Council Meteorology Group Meeting (RCC-MG) NASA Marshall Space Flight Center Range Report - April 2017

    NASA Technical Reports Server (NTRS)

    Roberts, Barry C.

    2017-01-01

    The following is a summary of the major meteorological/atmospheric projects and research that have been or currently are being accomplished at Marshall Space Flight Center (MSFC). Listed below are highlights of work done during the past 6 months in the Engineering Directorate (ED) and in the Science and Technology Office (ST).

  12. 107 Range Commanders Council Meteorology Group Meeting (RCC-MG): NASA Marshall Space Flight Center Range Report

    NASA Technical Reports Server (NTRS)

    Roberts, Barry C.

    2016-01-01

    The following is a summary of the major meteorological/atmospheric projects and research that have been or currently are being accomplished at Marshall Space Flight Center (MSFC). Listed below are highlights of work done during the past 6 months in the Engineering Directorate (ED) and in the Science and Mission Systems Office (ZP).

  13. The van der Waals potentials of MgCa, MgSr, MgBa, CaSr, CaBa, and SrBa

    NASA Astrophysics Data System (ADS)

    Wei, L. M.; Li, P.; Tang, K. T.

    2015-08-01

    Based on the facts that the potential energy curves of the homo-nuclear group 2 dimers (group IIA metal), except Be2, are conformal, and they can be described by the Tang-Toennies potential model, a set of simple combining rules are proposed for the parameters of the reduced potentials of the hetero-nuclear dimers. Together with the well-established combining rules of the range parameters of the exponential repulsion and the known dispersion coefficients, these rules enable us to determine the ground state potential energy curves of MgCa, MgSr, MgBa, CaSr, CaBa, and SrBa from those of Mg2, Ca2, Sr2, and Ba2. The determined potentials are comparable to some ab initio calculations and in excellent agreement with the experiment.

  14. An Overview of Fe-Mg Interdiffusion in Mantle Minerals

    NASA Astrophysics Data System (ADS)

    Zhang, Baohua

    2017-07-01

    The rates of Fe-Mg interdiffusion in the Earth's materials are of fundamental importance to a wide range of geochemistry and geophysics problems. In order that the Earth Scientist may readily apply the available experimentally determined diffusion rates to such problems, a brief review of experimental data for Fe-Mg interdiffusion in mantle minerals is presented concerning new advances and some recent applications. Perspectives for the future are also suggested.

  15. Daytime wakefulness following a bedtime oral dose of zolpidem 20 mg, flunitrazepam 2 mg and placebo.

    PubMed Central

    Bensimon, G; Foret, J; Warot, D; Lacomblez, L; Thiercelin, J F; Simon, P

    1990-01-01

    1. The effects of zolpidem 20 mg, flunitrazepam 2 mg and placebo, administered at bed time, were studied in 12 healthy young male volunteers. 2. The assessments included, at awakening, subjective ratings of overnight sleep, cognitive function, psychomotor performance (digit symbol substitution, choice reaction time, flicker fusion threshold), subjective ratings of alertness, and plasma assay of residual drug concentration. Daytime sleep propensity during the day after dosing was evaluated with the multiple sleep latency test. 3. Compared with placebo, both active drugs improved subjective assessment of the ease of getting to sleep. At awakening, under flunitrazepam treatment, the reduction of performance, on memory and psychomotor tests, paralleled an increased subjective rating of sleepiness, but zolpidem treatment left subjects unimpaired compared with placebo. Similarly, daytime sleep propensity was enhanced throughout the following day under flunitrazepam treatment, but not under zolpidem treatment. Plasma assay for residual drug concentration at awakening found significant amounts of flunitrazepam and marginal amounts of zolpidem. 4. Results indicate that zolpidem 20 mg is devoid of residual effects in a range of tasks that were sensitive enough to demonstrate a prolonged wakefulness impairment following flunitrzepam 2 mg in healthy volunteers. PMID:2223425

  16. Mg2+ coordinating dynamics in Mg:ATP fueled motor proteins

    NASA Astrophysics Data System (ADS)

    Bojovschi, A.; Liu, Ming S.; Sadus, Richard J.

    2014-03-01

    The coordination of Mg2+ with the triphosphate group of adenosine triphosphate (ATP) in motor proteins is investigated using data mining and molecular dynamics. The possible coordination structures available from crystal data for actin, myosin, RNA polymerase, DNA polymerase, DNA helicase, and F1-ATPase are verified and investigated further by molecular dynamics. Coordination states are evaluated using structural analysis and quantified by radial distribution functions, coordination numbers, and pair interaction energy calculations. The results reveal a diverse range of both transitory and stable coordination arrangements between Mg2+ and ATP. The two most stable coordinating states occur when Mg2+ coordinates two or three oxygens from the triphosphate group of ATP. Evidence for five-site coordination is also reported involving water in addition to the triphosphate group. The stable states correspond to a pair interaction energy of either ˜-2750 kJ/mol or -3500 kJ/mol. The role of water molecules in the hydration shell surrounding Mg2+ is also reported.

  17. Growth of high Mg content wurtzite MgZnO epitaxial films via pulsed metal organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Alema, Fikadu; Ledyaev, Oleg; Miller, Ross; Beletsky, Valeria; Osinsky, Andrei; Schoenfeld, Winston V.

    2016-02-01

    We report on the growth of high Mg content, high quality, wurtzite MgxZn1-xO (MgZnO) epitaxial films using a pulsed metal organic chemical vapor deposition (PMOCVD) method. Series of MgZnO films with variable Mg concentration were deposited on bare and AlN coated sapphire substrates. The band gap of the films estimated using UV-visible transmission spectra ranges from 3.24 eV to 4.49 eV, corresponding to fraction of Mg between x=0.0 and x=0.51, as determined by Rutherford backscattering spectroscopy. The cathodoluminescence (CL) measurement has shown a blue-shift in the peak position of MgZnO with an increasing Mg content. No multi-absorption edges and CL band splitting were observed, suggesting the absence of phase segregation in the as grown films. The crystal structure and phase purity of the films were also confirmed by XRD analysis. Hall effect measurement in van der Pauw configuration was employed to evaluate the electrical properties of the films. With a rise in Mg incorporation into the ZnO lattice, the films became very resistive, consistent with the widening of the band gap. The AFM measurement on the films has shown a decreasing surface roughness with an Mg content. To the best of our knowledge, the current result shows the highest Mg content (x=0.51), high quality, wurtzite MgZnO epitaxial film ever grown by MOCVD. The high Mg incorporation without phase separation is believed to be due to the non-equilibrium behavior of the PMOCVD in which the kinetic processes dominate the thermodynamic one.

  18. Range management visual impacts

    Treesearch

    Bruce R. Brown; David Kissel

    1979-01-01

    Historical overgrazing of western public rangelands has resulted in the passage of the Public Rangeland Improvement Act of 1978. The main purpose of this Act is to improve unsatisfactory range conditions. A contributing factor to unfavorable range conditions is adverse visual impacts. These visual impacts can be identified in three categories of range management: range...

  19. Size effects in MgO cube dissolution.

    PubMed

    Baumann, Stefan O; Schneider, Johannes; Sternig, Andreas; Thomele, Daniel; Stankic, Slavica; Berger, Thomas; Grönbeck, Henrik; Diwald, Oliver

    2015-03-10

    Stability parameters and dissolution behavior of engineered nanomaterials in aqueous systems are critical to assess their functionality and fate under environmental conditions. Using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we investigated the stability of cubic MgO particles in water. MgO dissolution proceeding via water dissociation at the oxide surface, disintegration of Mg(2+)-O(2-) surface elements, and their subsequent solvation ultimately leads to precipitation of Mg(OH)2 nanosheets. At a pH ≥ 10, MgO nanocubes with a size distribution below 10 nm quantitatively dissolve within few minutes and convert into Mg(OH)2 nanosheets. This effect is different from MgO cubes originating from magnesium combustion in air. With a size distribution in the range 10 nm ≤ d ≤ 1000 nm they dissolve with a significantly smaller dissolution rate in water. On these particles water induced etching generates (110) faces which, above a certain face area, dissolve at a rate equal to that of (100) planes.1 The delayed solubility of microcrystalline MgO is attributed to surface hydroxide induced self-inhibition effects occurring at the (100) and (110) microplanes. The present work underlines the importance of morphology evolution and surface faceting of engineered nanomaterials particles during their dissolution.

  20. Range Reference Notebook

    DTIC Science & Technology

    2006-10-15

    rifle grenade (inert), tin can lid, 15” tent peg 3 Table FRD-7. Fort Ritchie Sector 3 Representative Examples of Non-MEC Clutter Description 1/2...Appendix B—Indirect Fire Range Examples SITES ( ADI ) Adak Naval Air Facility, AK, Mitt Lake Mortar Range (FRI) Fort Ritchie...example range. B- ADI -1 Indirect-Fire Range,: Adak, AK, Mitt Lake Mortar Range Impact Area Site-Specific References – Adak NAF Foster Wheeler

  1. A Long-Range Precision Ranging System

    NASA Technical Reports Server (NTRS)

    Easterling, Mahlon

    1961-01-01

    A technique is presented that may be used for precision real-time continuous range measuring at long ranges. The technique uses a carrier that is phase modulated by a pseudo-random binary sequence. The characteristics of the sequence that make it acquirable are discussed. The general form of a receiver capable of tracking the carrier is given and is shown to be a kind of phase-locked loop. A two-loop system capable of tracking a pseudo-random sequence and its clock is given. The combination of the receiver and the sequence tracking system form a ranging receiver. The power division necessary between the carrier and the sidebands is shown to be determined by the noise bandwidths of the two tracking systems. The bandwidths necessary for tracking space probes and Earth satellites are given and some experiments in radar-tracking Earth satellites are described. Based on these experiments, estimates are made of the useful range of such a system in tracking space probes.

  2. LOW Mg/Si PLANETARY HOST STARS AND THEIR Mg-DEPLETED TERRESTRIAL PLANETS

    SciTech Connect

    Carter-Bond, Jade C.; O'Brien, David P.; Delgado Mena, Elisa; Israelian, Garik; Gonzalez Hernandez, Jonay I.; Santos, Nuno C.

    2012-03-15

    Simulations have shown that a diverse range of extrasolar terrestrial planet bulk compositions are likely to exist based on the observed variations in host star elemental abundances. Based on recent studies, it is expected that a significant proportion of host stars may have Mg/Si ratios below 1. Here we examine this previously neglected group of systems. Planets simulated as forming within these systems are found to be Mg-depleted (compared to Earth), consisting of silicate species such as pyroxene and various feldspars. Planetary carbon abundances also vary in accordance with the host star C/O ratio. The predicted abundances are in keeping with observations of polluted white dwarfs, lending validity to this approach. Further studies are required to determine the full planetary impacts of the bulk compositions predicted here.

  3. Room-temperature perpendicular magnetic anisotropy of MgO/Fe/MgO ultrathin films

    SciTech Connect

    Kozioł-Rachwał, A.; Ślęzak, T.; Przewoźnik, J.; Skowroński, W.; Stobiecki, T.; Wilgocka-Ślęzak, D.; Qin, Q. H.; Dijken, S. van; Korecki, J.

    2013-12-14

    We used the anomalous Hall effect to study the magnetic properties of MgO/Fe(t)/MgO(001) structures in which the Fe thickness t ranged from 4 Å to 14 Å. For the iron deposited at 140 K, we obtained perpendicular magnetization at room temperature below the critical thickness of t{sub c} = (9 ± 1) Å. In the vicinity of t{sub c}, the easy magnetization axis switched from an out-of-plane orientation to an in-plane orientation, and the observed spin-reorientation transition was considered in terms of the competition among different anisotropies. The perpendicular magnetization direction was attributed to magnetoelastic anisotropy. Finally, the temperature-dependent spin-reorientation transition was analyzed for Fe thicknesses close to t{sub c}.

  4. Ab-initio calculations of semiconductor MgGeP{sub 2} and MgGeAs{sub 2}

    SciTech Connect

    Kocak, B.; Ciftci, Y.O.

    2016-05-15

    Highlights: • MgGeP{sub 2} and MgGeAs{sub 2} are semiconductor compounds. • MgGeP{sub 2} and MgGeAs{sub 2} are energetically, mechanically and dynamically stable. • The electronic charge density contour plot shows that the nature of bonding is a mixture of ionic-covalent. - Abstract: In this study, we focus on structural, electronic, elastic, lattice dynamic and optic properties of MgGeP{sub 2} and MgGeAs{sub 2} using ab-initio density-functional theory (DFT) within Armiento-Mattson 2005 (AM05) scheme of the generalized gradient approximation (GGA) for the exchange-correlation potential. Our computed structural results are in reasonable agreement with the literature. The band gap of these compounds is predicted to be direct. Our elastic results prove that these compounds are mechanically stable. The obtained phonon spectra of MgGeP{sub 2} and MgGeAs{sub 2} do not exhibit any significant imaginary branches using GGA-AM05 for the exchange-correlation approximation. Further analysis of the optical response of the dielectric functions, optical reflectivity, refractive index, extinction coefficient and electron energy loss delves into for the energy range of 0–22.5 eV. It motivated that there exists an optical polarization anisotropy of these compounds for optoelectronic device applications.

  5. Ultra-high Strength Nanostructured Mg

    DTIC Science & Technology

    2014-03-31

    27709-2211 Nanostructured Mg and Mg alloys, Mg metallic glass, Cryomilling, Powder consolidation, Spark plasma sintering , Deformation mechanisms REPORT...mechanically milled powder and high pressure on spark plasma sintering of Mg-Cu-Gd metallic glasses; (9) microstructure and mechanical behavior of Mg-10Li-3Al...pressure on spark plasma sintering of Mg– Cu–Gd metallic glasses, Acta Materialia , (07 2013): 4414. doi: Baolong Zheng, Ying Li, Weizong Xu

  6. Bioequivalence of a single 400-mg dose of imatinib 100-mg oral tablets and a 400-mg tablet in healthy adult Korean volunteers.

    PubMed

    Lee, Hae Won; Seong, Sook Jin; Park, Sung Min; Lee, Joomi; Gwon, Mi-Ri; Kim, Hyun-Ju; Lim, Sung Mook; Lim, Mi-Sun; Kim, Woomi; Yang, Dong Heon; Yoon, Young-Ran

    2015-06-01

    Imatinib mesylate (IM) is a selective tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors. A new once-daily 400-mg film-coated tablet of imatinib has been developed by a pharmaceutical company in Korea. The present study was designed to assess and compare the PK parameters, bioavailability, and bioequivalence of the new imatinib 400-mg formulation (test) versus the conventional 100-mg formulation (reference) administered as a single 400-mg dose in healthy adult male volunteers. This randomized, open-label, single-dose, two-way crossover study was conducted in healthy Korean male volunteers. Eligible subjects were randomly assigned in a 1 : 1 ratio to receive 400 mg of the test (one 400-mg tablet) or reference (four 100-mg tablets) formulation, followed by a 2-week washout period and administration of the alternate formulation. Serial blood samples were collected at 0 (predose), 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 24, 48, and 72 hours after administration. Plasma imatinib concentrations were determined using liquid chromatography coupled with tandem mass spectrometry. The formulations were to be considered bioequivalent if the 90% confidence intervals (CIs) of the adjusted geometric mean ratios for Cmax, AUC(0-t), and AUC(0-∞)ž were within the predetermined range of 0.80 - 1.25. In total, 35 subjects completed the study. No serious adverse event was reported during the study. The 90% CIs of the adjusted geometric mean ratios of the test formulation to the reference formulation for C(max), AUC(0-t) and AUC(0-∞)ž of imatinib were all within the bioequivalence criteria range of 0.8 - 1.25. The test formulation of imatinib met the Korean regulatory requirements for bioequivalence. Both imatinib formulations were well-tolerated in all subjects.

  7. Global Mapping of Mg-Number Derived from Clementine Data.

    NASA Astrophysics Data System (ADS)

    Cahill, J. T.; Lucey, P. G.; Gillis, J. J.; Steutel, D.

    2004-12-01

    environmental space exposure on the optical properties of these minerals. This was accomplished using Clementine ultraviolet and visible (UVVIS) data and a Hapke radiative transfer mixing model. The major features evident in these maps are the strong distinction between mare and highland regions, the former showing low Mg* and the latter generally higher; a large northern highlands unit with low Mg*, and an Mg* high north of South Pole-Aitken basin. Mare units are not universally low, mare Frigoris in particular has elevated Mg* relative to other mare. The strongest variations in the highlands occur in plagioclase rich, low FeO units, that exhibit values ranging near 50 to near 100 in coherent units. The craters Tycho and Aristarchus also exhibit high Mg*; these gabbroic anomalies may indicate more extensive Mg-rich material at depth. Deposits within SPA are unremarkable relative to surroundings, and share the intermediate Mg* of most of the highlands. 1. James, O.B. et al. PLPSC. 1989.; 2.Bersch, M.G., et al., GRL, 1991.; 3. Floss, C., et al., GCA, 1998.; 4. Korotev, R.L., et al., GCA, 2003.

  8. Mg fractionation in crustose coralline algae: Geochemical, biological, and sedimentological implications of secular variation in the Mg/Ca ratio of seawater

    NASA Astrophysics Data System (ADS)

    Ries, Justin B.

    2006-02-01

    The Mg/Ca ratio of seawater has varied significantly throughout the Phanerozoic Eon, primarily as a function of the rate of ocean crust production. Specimens of the crustose coralline alga Neogoniolithon sp. were grown in artificial seawaters encompassing the range of Mg/Ca ratios shown to have existed throughout the Phanerozoic. Significantly, the coralline algae's skeletal Mg/Ca ratio varied in lockstep with the Mg/Ca ratio of the artificial seawater. Specimens grown in seawater treatments formulated with identical Mg/Ca ratios but differing absolute concentrations of Mg and Ca exhibited no significant differences in skeletal Mg/Ca ratios, thereby emphasizing the importance of the ambient Mg/Ca ratio, and not the absolute concentration of Mg, in determining the Mg/Ca ratio of coralline algal calcite. Specimens grown in seawater of the lowest molar Mg/Ca ratio ( mMg/Ca = 1.0) actually changed their skeletal mineralogy from high-Mg (skeletal mMg/Ca > 0.04) to low-Mg calcite (skeletal mMg/Ca < 0.04), suggesting that ancient calcitic red algae, which exhibit morphologies and modes of calcification comparable to Neogoniolithon sp., would have produced low-Mg calcite from the middle Cambrian to middle Mississippian and during the middle to Late Cretaceous, when oceanic mMg/Ca approached unity. By influencing the original Mg content of carbonate facies in which these algae have been ubiquitous, this condition has significant implications for the geochemistry and diagenesis of algal limestones throughout most of the Phanerozoic. The crustose coralline algae's precipitation of high-Mg calcite from seawater that favors the abiotic precipitation of aragonite indicates that these algae dictate the precipitation of the calcitic polymorph of CaCO 3. However, the algae's nearly abiotic pattern of Mg fractionation in their skeletal calcite suggests that their biomineralogical control is limited to polymorph specification and is generally ineffectual in the regulation of skeletal

  9. Limited range of motion

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003173.htm Limited range of motion To use the sharing features on this page, please enable JavaScript. Limited range of motion is a term meaning that a joint or ...

  10. Television Tracker Range Equation

    NASA Astrophysics Data System (ADS)

    Huan-Wen, Zhu

    1987-05-01

    The paper gives an approximate television tracker range equation based on the concept of the radiology and signal-to-noise of television system, and describes the physical process and mathematical method of reckoning range equation. The range equation is useful to the desing and development of a system. This paper also discusses the demand and selection standard of the television tracker system to the imaging device and gives some possible approaches to increase the range.

  11. RADIO RANGING DEVICE

    DOEpatents

    Nieset, R.T.

    1961-05-16

    A radio ranging device is described. It utilizes a super regenerative detector-oscillator in which echoes of transmitted pulses are received in proper phase to reduce noise energy at a selected range and also at multiples of the selected range.

  12. Long Range Technology Planning.

    ERIC Educational Resources Information Center

    Ambron, Sueann, Ed.

    1986-01-01

    This summary of a meeting of the Apple Education Advisory Council, on long range technology plans at the state, county, district, and school levels, includes highlights from group discussions on future planning, staff development, and curriculum. Three long range technology plans at the state level are provided: Long Range Educational Technology…

  13. Long Range Technology Planning.

    ERIC Educational Resources Information Center

    Ambron, Sueann, Ed.

    1986-01-01

    This summary of a meeting of the Apple Education Advisory Council, on long range technology plans at the state, county, district, and school levels, includes highlights from group discussions on future planning, staff development, and curriculum. Three long range technology plans at the state level are provided: Long Range Educational Technology…

  14. Tau ranging revisited

    NASA Technical Reports Server (NTRS)

    Tausworthe, R. C.

    1987-01-01

    It is shown that a ranging receiver with a sufficient and reasonable number of correlators is competitive with the current sequential component ranging system by some 1.5 to 2.5 dB. The optimum transmitter code, the optimum receiver, and a near-maximum-lilelihood range-estimation algorithm are presented.

  15. Resetting of Mg isotopes between calcite and dolomite during burial metamorphism: Outlook of Mg isotopes as geothermometer and seawater proxy

    NASA Astrophysics Data System (ADS)

    Hu, Zhongya; Hu, Wenxuan; Wang, Xiaomin; Lu, Yizhou; Wang, Lichao; Liao, Zhiwei; Li, Weiqiang

    2017-07-01

    Magnesium isotopes are an emerging tool to study the geological processes recorded in carbonates. Calcite, due to its ubiquitous occurrence and the large Mg isotope fractionation associated with the mineral, has attracted great interests in applications of Mg isotope geochemistry. However, the fidelity of Mg isotopes in geological records of carbonate minerals (e.g., calcite and dolomite) against burial metamorphism remains poorly constrained. Here we report our investigation on the Mg isotope systematics of a dolomitized Middle Triassic Geshan carbonate section in eastern China. Magnesium isotope analysis was complemented by analyses of Sr-C-O isotopic compositions, major and trace element concentrations, and petrographic and mineralogical features. Multiple lines of evidence consistently indicated that post-depositional diagenesis of carbonate minerals occurred to the carbonate rocks. Magnesium isotope compositions of the carbonate rocks closely follow a mixing trend between a high δ26Mg dolomite end member and a low δ26Mg calcite end member, irrespective of sample positions in the section and calcite/dolomite ratio in the samples. By fitting the measured Mg isotope data using a two-end member mixing model, an inter-mineral Δ26Mgdolomite-calcite fractionation of 0.72‰ was obtained. Based on the experimentally derived Mg isotope fractionation factors for dolomite and calcite, a temperature of 150-190 °C was calculated to correspond to the 0.72‰ Δ26Mgdolomite-calcite fractionation. Such temperature range matches with the burial-thermal history of the local strata, making a successful case of Mg isotope geothermometry. Our results indicate that both calcite and dolomite had been re-equilibrated during burial metamorphism, and based on isotope mass balance of Mg, the system was buffered by dolomite in the section. Therefore, burial metamorphism may reset Mg isotope signature of calcite, and Mg isotope compositions in calcite should be dealt with caution in

  16. High-precision Mg isotopic systematics of bulk chondrites

    NASA Astrophysics Data System (ADS)

    Schiller, Martin; Handler, Monica R.; Baker, Joel A.

    2010-08-01

    chondrite parent bodies had precisely the same initial levels of 26Al, although planetesimals and planets appear to have accreted from material with a mean initial ( 26Al/ 27Al) 0 in the range of 2.1 to 6.7 × 10 - 5 . The average stable Mg isotope composition of all analysed chondrites, with the exception of a chondrule from the CBa chondrite Gujba ( δ25Mg DSM-3 = -0.032 ± 0.035‰), is δ25Mg DSM-3 = -0.152 ± 0.079‰ (2 sd) and is indistinguishable from that of the Earth's mantle.

  17. Telemetry Ranging: Signal Processing

    NASA Astrophysics Data System (ADS)

    Hamkins, J.; Kinman, P.; Xie, H.; Vilnrotter, V.; Dolinar, S.

    2016-02-01

    This article describes the details of the signal processing used in a telemetry ranging system in which timing information is extracted from the downlink telemetry signal in order to compute spacecraft range. A previous article describes telemetry ranging concepts and architecture, which are a slight variation of a scheme published earlier. As in that earlier work, the telemetry ranging concept eliminates the need for a dedicated downlink ranging signal to communicate the necessary timing information. The present article describes the operation and performance of the major receiver functions on the spacecraft and the ground --- many of which are standard tracking loops already in use in JPL's flight and ground radios --- and how they can be used to provide the relevant information for making a range measurement. It also describes the implementation of these functions in software, and performance of an end-to-end software simulation of the telemetry ranging system.

  18. Characterization of Mg2+ Distributions around RNA in Solution

    PubMed Central

    2016-01-01

    Binding of metal ions is an important factor governing the folding and dynamics of RNA. Shielding of charges in the polyanionic backbone allows RNA to adopt a diverse range of folded structures that give rise to their many functions within the cell. Some RNA sequences fold only in the presence of Mg2+, which may be bound via direct interactions or occupy the more diffuse “ion atmosphere” around the RNA. To understand the driving forces for RNA folding, it is important to be able to fully characterize the distribution of metal ions around the RNA. In this work, a combined Grand Canonical Monte Carlo-Molecular Dynamics (GCMC-MD) method is applied to characterize Mg2+ distributions around folded RNA structures. The GCMC-MD approach identifies known inner- and outer-shell Mg2+ coordination, while also predicting new regions occupied by Mg2+ that are not observed in crystal structures but that may be relevant in solution, including the case of the Mg2+ riboswitch, for which alternate Mg2+ binding sites may have implications for its function. This work represents a significant step forward in establishing a structural and thermodynamic description of RNA–Mg2+ interactions and their role in RNA structure and function. PMID:27819065

  19. ZnCdMgSe-Based Semiconductors for Intersubband Devices

    SciTech Connect

    Tamargo, Maria C.

    2008-11-13

    This paper presents a review of recent results on the application of ZnCdMgSe-based wide bandgap II-VI compounds to intersubband devices such as quantum cascade lasers and quantum well infrared photodetectors operating in the mid-infrared region. The conduction band offset of ZnCdSe/ZnCdMgSe quantum well structures was determined from contactless electroreflectance measurements to be as high as 1.12 eV. FT-IR was used to measure intersubband absorption in multi-quantum well structures in the mid-IR range. Electroluminescence at 4.8 {mu}m was observed from a quantum cascade emitter structure made from these materials. Preliminary results are also presented on self assembled quantum dots of CdSe on ZnCdMgSe, and novel quantum well structures with metastable binary MgSe barriers.

  20. Telemetry-Based Ranging

    NASA Technical Reports Server (NTRS)

    Hamkins, Jon; Vilnrotter, Victor A.; Andrews, Kenneth S.; Shambayati, Shervin

    2011-01-01

    A telemetry-based ranging scheme was developed in which the downlink ranging signal is eliminated, and the range is computed directly from the downlink telemetry signal. This is the first Deep Space Network (DSN) ranging technology that does not require the spacecraft to transmit a separate ranging signal. By contrast, the evolutionary ranging techniques used over the years by NASA missions, including sequential ranging (transmission of a sequence of sinusoids) and PN-ranging (transmission of a pseudo-noise sequence) whether regenerative (spacecraft acquires, then regenerates and retransmits a noise-free ranging signal) or transparent (spacecraft feeds the noisy demodulated uplink ranging signal into the downlink phase modulator) relied on spacecraft power and bandwidth to transmit an explicit ranging signal. The state of the art in ranging is described in an emerging CCSDS (Consultative Committee for Space Data Systems) standard, in which a pseudo-noise (PN) sequence is transmitted from the ground to the spacecraft, acquired onboard, and the PN sequence is coherently retransmitted back to the ground, where a delay measurement is made between the uplink and downlink signals. In this work, the telemetry signal is aligned with the uplink PN code epoch. The ground station computes the delay between the uplink signal transmission and the received downlink telemetry. Such a computation is feasible because symbol synchronizability is already an integral part of the telemetry design. Under existing technology, the telemetry signal cannot be used for ranging because its arrival-time information is not coherent with any Earth reference signal. By introducing this coherence, and performing joint telemetry detection and arrival-time estimation on the ground, a high-rate telemetry signal can provide all the precision necessary for spacecraft ranging.

  1. Comparison of 1 mg and 2 mg overnight dexamethasone suppression tests for the screening of Cushing's syndrome in obese patients.

    PubMed

    Sahin, Mustafa; Kebapcilar, Levent; Taslipinar, Abdullah; Azal, Omer; Ozgurtas, Taner; Corakci, Ahmet; Akgul, Emin Ozgur; Taslipinar, Mine Yavuz; Yazici, Mahmut; Kutlu, Mustafa

    2009-01-01

    Obesity is currently a major public health problem and one of the potential underlying causes of obesity in a minority of patients is Cushing's syndrome (CS). Traditionally, the gold standard screening test for CS is 1 mg dexamethasone overnight suppression test. However, it is known that obese subjects have high false positive results with this test. We have therefore compared the 1 mg and 2 mg overnight dexamethasone suppression tests in obese subjects. Patients whose serum cortisol after ODST was >50 nM underwent and a low-dose dexamethasone suppression test (LDDST); 24-hour urine cortisol was collected for basal urinary free cortisol (UFC). For positive results after overnight 1-mg dexamethasone suppression test we also performed the overnight 2-mg dexamethasone suppression test. We prospectively evaluated 100 patients (22 men and 78 women, ranging in age from 17 to 73 years with a body mass index (BMI) >30 kg/m2 who had been referred to our hospital-affiliated endocrine clinic because of simple obesity. Suppression of serum cortisol to <50 nM (1.8 microg/dL) after dexamethasone administration was chosen as the cut-off point for normal suppression. Thyroid function tests, lipid profiles, homocysteine, antithyroglobulin, anti-thyroid peroxidase antibody levels, vitamin B12, folate levels, insulin resistance [by homeostasis model assessment (HOMA)] and 1.0 mg postdexamethasone (postdex) suppression cortisol levels were measured. We found an 8% false-positive rate in 1 mg overnight test and 2% in 2 mg overnight test (p=0.001). There was no correlation between the cortisol levels after ODST and other parameters. Our results indicate that the 2 mg overnight dexamethasone suppression test (ODST) is more convenient and accurate than 1-mg ODST as a screening test for excluding CS in subjects with simple obesity.

  2. Soil Moisture Mapping at a Watershed of the Mantiqueira Range, MG, Brazil

    USDA-ARS?s Scientific Manuscript database

    Soil moisture is an important hydrological variable that characterizes the soil water dynamics influencing surface runoff generation and consequently sediment transport. This work aimed to analyze the spatial patterns of surface soil moisture, to identify the elements that exert the most influence i...

  3. Micron Accurate Absolute Ranging System: Range Extension

    NASA Technical Reports Server (NTRS)

    Smalley, Larry L.; Smith, Kely L.

    1999-01-01

    The purpose of this research is to investigate Fresnel diffraction as a means of obtaining absolute distance measurements with micron or greater accuracy. It is believed that such a system would prove useful to the Next Generation Space Telescope (NGST) as a non-intrusive, non-contact measuring system for use with secondary concentrator station-keeping systems. The present research attempts to validate past experiments and develop ways to apply the phenomena of Fresnel diffraction to micron accurate measurement. This report discusses past research on the phenomena, and the basis of the use Fresnel diffraction distance metrology. The apparatus used in the recent investigations, experimental procedures used, preliminary results are discussed in detail. Continued research and equipment requirements on the extension of the effective range of the Fresnel diffraction systems is also described.

  4. MgB2 tunnel junctions with native or thermal oxide barriers

    NASA Astrophysics Data System (ADS)

    Singh, R. K.; Gandikota, R.; Kim, J.; Newman, N.; Rowell, J. M.

    2006-07-01

    MgB2 tunnel junctions (MgB2/barrier/MgB2) were fabricated using a native oxide grown on the bottom MgB2 film as the tunnel barrier. Such barriers therefore survive the deposition of the second electrode at 300°C, even over junction areas of ˜1mm2. Studies of such junctions and those of the type MgB2/native or thermal oxide/metal (Pb, Au, or Ag) show that tunnel barriers grown on MgB2 exhibit a wide range of barrier heights and widths.

  5. Comparison between the low temperature thermoluminescence spectra in annealed LiF:Mg,Cu, LiF:Mg,Cu,P and LiF:Mg,Cu,Si

    NASA Astrophysics Data System (ADS)

    Yang, B.; Wang, L.; Townsend, P. D.; Gao, H.

    2008-06-01

    Two strong thermal peaks in the wavelength range 220-420 nm have been detected at 128 and 140 K in LiF:Mg,Cu, at 123 and 135 K in LiF:Mg,Cu,P and at 125 and 133 K in LiF:Mg,Cu,Si, respectively. The origin of these main TL peaks is discussed in terms of defect perturbed H-F and VK-e type recombination, respectively. The relative intensity between the two peaks in each sample and the emission spectra are dependent on the dopants. Annealing at 240-390 °C can modify the low temperature TL features, especially in those samples doped with three impurities. The low temperature data give some clues to select most favourable dopants for future LiF-type dosimeters.

  6. Compressive laser ranging.

    PubMed

    Babbitt, Wm Randall; Barber, Zeb W; Renner, Christoffer

    2011-12-15

    Compressive sampling has been previously proposed as a technique for sampling radar returns and determining sparse range profiles with a reduced number of measurements compared to conventional techniques. By employing modulation on both transmission and reception, compressive sensing in ranging is extended to the direct measurement of range profiles without intermediate measurement of the return waveform. This compressive ranging approach enables the use of pseudorandom binary transmit waveforms and return modulation, along with low-bandwidth optical detectors to yield high-resolution ranging information. A proof-of-concept experiment is presented. With currently available compact, off-the-shelf electronics and photonics, such as high data rate binary pattern generators and high-bandwidth digital optical modulators, compressive laser ranging can readily achieve subcentimeter resolution in a compact, lightweight package.

  7. Highly (100) oriented MgO growth on thin Mg layer in MTJ structure

    NASA Astrophysics Data System (ADS)

    Jimbo, K.; Nakagawa, S.

    2011-01-01

    In order to apply Stress Assisted Magnetization Reversal (SAMR) method to perpendicular magnetoresistive random access memory (p-MRAM) with magnetic tunnel junction (MTJ) using MgO (001) oriented barrier layer, multilayer of Ta/ Terfenol-D/ Mg/ MgO and Ta/ Terfenol-D/ MgO were prepared. While the MgO layer, deposited directly on the Terfenol-D layer, did not show (100) orientatin, very thin metallic Mg layer, deposited prior to the MgO deposition, was effective to attain MgO (100) orientation. The crystalline orientation was very weak without Mg, however, the multilayer with Mg showed very strong MgO(100) peak and the MgO orientation was shifted depending on the Mg thickness.

  8. Vonoprazan 20 mg vs lansoprazole 30 mg for endoscopic submucosal dissection-induced gastric ulcers

    PubMed Central

    Takahashi, Kazuya; Sato, Yuichi; Kohisa, Junji; Watanabe, Jun; Sato, Hiroki; Mizuno, Kenichi; Hashimoto, Satoru; Terai, Shuji

    2016-01-01

    AIM To compare the healing effects of vonoprazan and lansoprazole on gastric ulcers induced by endoscopic submucosal dissection (ESD). METHODS Data were obtained from a total of 26 patients. Fourteen patients were randomized to the vonoprazan group and 12 were randomized to the lansoprazole group. Patients were administered either 20 mg vonoprazan or 30 mg lansoprazole per day after ESD. Endoscopic images just after ESD, on day 8, and on day 28 were used for the evaluation of the shrinking rate of ESD ulcers. The shrinking rates and the incidence of delayed bleeding were compared between the 2 groups. RESULTS The shrinking rates of ESD ulcers on day 8 [vonoprazan group: 61.8% (range: 24.0%-91.1%), lansoprazole group: 71.3% (range: 25.2%-88.6%)] and on day 28 [vonoprazan group: 95.3% (range: 76.2%-100%), lansoprazole group: 97.2% (range: 81.1%-99.8%)] were not statistically different between the 2 groups. On day 28, most of the ulcers in both groups healed to more than 90%, whereas 3 of 14 (21.4%) in the vonoprazan group and 1 of 12 (8.3%) in the lansoprazole group had delayed ulcer healing, which was not statistically different (P = 0.356). The frequency of delayed bleeding was 0 in the both groups. Taken together, there were no significant differences between the two drug groups. CONCLUSION Our study indicates that vonoprazan is potent for the management of ESD ulcers although lansoprazole is also sufficient and cost-effective. PMID:27909552

  9. Laser Ranging System

    NASA Technical Reports Server (NTRS)

    Russell, J. K.

    1986-01-01

    Laser system points and focuses TV camera. Ranger is modified stock distance-measuring unit mounted on and electrically connected to television camera. Effective over target range of 3 to 500 ft. (approximately 1 to 150m). Developed for television monitoring of nearby objects from Space Shuttle. Super-imposes range and range-rate (speed of approach or recession) data on television image of target. Principle adaptable to applications such as proximity warning and robot control.

  10. Improved ranging systems

    NASA Technical Reports Server (NTRS)

    Young, Larry E.

    1989-01-01

    Spacecraft range measurements have provided the most accurate tests, to date, of some relativistic gravitational parameters, even though the measurements were made with ranging systems having error budgets of about 10 meters. Technology is now available to allow an improvement of two orders of magnitude in the accuracy of spacecraft ranging. The largest gains in accuracy result from the replacement of unstable analog components with high speed digital circuits having precisely known delays and phase shifts.

  11. Automatic range selector

    DOEpatents

    McNeilly, Clyde E.

    1977-01-04

    A device is provided for automatically selecting from a plurality of ranges of a scale of values to which a meter may be made responsive, that range which encompasses the value of an unknown parameter. A meter relay indicates whether the unknown is of greater or lesser value than the range to which the meter is then responsive. The rotatable part of a stepping relay is rotated in one direction or the other in response to the indication from the meter relay. Various positions of the rotatable part are associated with particular scales. Switching means are sensitive to the position of the rotatable part to couple the associated range to the meter.

  12. Range criterion for separability

    SciTech Connect

    Ha, Kil-Chan

    2010-12-15

    Horodecki formulated a remarkable criterion for separability, which is called the range criterion. This range criterion was mostly used to show that some states with positive partial transpose are entangled. In this Brief Report, we show that the range criterion is also useful to find a convex combination of product states for a separable state. For this purpose, we give an example of density matrix, which is separable in a 2 x 3 system and entangled in a 3 x 2 system at the same time. Then we illustrate the usefulness of the range criterion with this example.

  13. Alterations of Mg(2+) After Hemorrhagic Shock.

    PubMed

    Lee, Mun-Young; Yang, Dong Kwon; Kim, Shang-Jin

    2017-03-17

    Hemorrhagic shock is generally characterized by hemodynamic instability with cellular hypoxia and diminishing cellular function, resulting from an imbalance between systemic oxygen delivery and consumption and redistribution of fluid and electrolytes. Magnesium (Mg) is the fourth most abundant cation overall and second most abundant intracellular cation in the body and an essential cofactor for the energy production and cellular metabolism. Data for blood total Mg (tMg; free-ionized, protein-bound, and anion-bound forms) and free Mg(2+) levels after a traumatic injury are inconsistent and only limited information is available on hemorrhagic effects on free Mg(2+) as the physiologically active form. The aim of this study was to determine changes in blood Mg(2+) and tMg after hemorrhage in rats identifying mechanism and origin of the changes in blood Mg(2+). Hemorrhagic shock produced significant increases in blood Mg(2+), plasma tMg, Na(+), K(+), Cl(-), anion gap, partial pressures of oxygen, glucose, and blood urea nitrogen but significant decreases in RBC tMg, blood Ca(2+), HCO3(-), pH, partial pressures of carbon dioxide, hematocrit, hemoglobin, total cholesterol, and plasma/RBC ATP. During hemorrhagic shock, K(+), anion gap, and BUN showed significant positive correlations with changes in blood Mg(2+) level, while Ca(2+), pH, and T-CHO correlated to Mg(2+) in a negative manner. In conclusion, hemorrhagic shock induced an increase in both blood-free Mg(2+) and tMg, resulted from Mg(2+) efflux from metabolic damaged cell with acidosis and ATP depletion.

  14. The coordination of Mg in foraminiferal calcite

    NASA Astrophysics Data System (ADS)

    Branson, Oscar; Redfern, Simon A. T.; Tyliszczak, Tolek; Sadekov, Aleksey; Langer, Gerald; Kimoto, Katsunori; Elderfield, Henry

    2013-12-01

    The Mg/Ca ratio of foraminiferal calcite is a widely accepted and applied empirical proxy for ocean temperature. The analysis of foraminifera preserved in ocean sediments has been instrumental in developing our understanding of global climate, but the mechanisms behind the proxy are largely unknown. Analogies have been drawn to the inorganic precipitation of calcite, where the endothermic substitution of Mg for Ca is favoured at higher temperatures. However, evidence suggests that foraminiferal Mg incorporation may be more complex: foraminiferal magnesium is highly heterogeneous at the sub-micron scale, and high Mg areas coincide with elevated concentrations of organic molecules, Na, S and other trace elements. Fundamentally, the incorporation mode of Mg in foraminifera is unknown. Here we show that Mg is uniformly substituted for Ca within the calcite mineral lattice. The consistency of Mg-specific X-ray spectra gathered from nano-scale regions across the shell (‘test’) reveals that the coordination of Mg is uniform. The similarity of these spectra to that produced by dolomite shows that Mg is present in an octahedral coordination, ideally substituted for Ca in a calcite crystal structure. This demonstrates that Mg is heterogeneous in concentration, but not in structure. The degree of this uniformity implies the action of a continuous Mg incorporation mechanism, and therefore calcification mechanism, across these compositional bands in foraminifera. This constitutes a fundamental step towards a mechanistic understanding of foraminiferal calcification processes and the incorporation of calcite-bound palaeoenvironment proxies, such as Mg.

  15. Reversible S0/MgSx Redox Chemistry in MgTFSI2-MgCl2 Electrolyte for Rechargeable Mg/S Battery.

    PubMed

    Gao, Tao; Hou, Singyuk; Wang, Fei; Ma, Zhaohui; Li, Xiaogang; Xu, Kang; Wang, Chunsheng

    2017-08-28

    Magnesium redox chemistries are attracting growing attentions for rechargeable Mg batteries due to the unique benefits of Mg metal electrode: high reversibility without dendrite, low reduction potential and high specific capacity. Mg/S couple is of particular interest due to its high energy density (1700 Wh/kg and 3200 Wh/L) and low cost. Previous reports have justified the feasibility of a rechargeable Mg/S battery; however, only limited cycling stability was achieved, and the complicated preparation procedure of the electrolytes have significantly compromised the benefits of Mg/S chemistry, and hindered the development of Mg/S battery. Herein, we report the first rechargeable Mg/S battery using MgTFSI2-MgCl2-DME electrolyte and demonstrate the best cycling stability among all reported Mg/S batteries by suppressing polysulfide dissolution. Mechanistic study shows the battery works via S0/MgSx redox and the large voltage hysteresis mainly origins from Mg anode overpotential. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Mg isotopes geochemistry in the Han River basin, Korea

    NASA Astrophysics Data System (ADS)

    Ryu, J.; Lee, S.; Lee, K.; Shin, H.

    2012-12-01

    The Han River basin is the largest river system in South Korea, consisting of two major branches: the North Han River (NHR) and South Han River (SHR). Distinct differences in the lithology between the NHR and SHR (silicates vs. carbonates) allow us to constrain the behavior of Mg isotopes during chemical weathering. We collected water samples as well as rock samples in summer 2011. The lithological difference between the NHR and SHR is reflected in major ions and dissolved Sr isotope compositions; lower major ion concentrations and high 87Sr/86Sr ratios in the NHR but higher major ion concentrations and low 87Sr/86Sr ratios in the SHR. Dissolved Mg in the NHR yielded heavier Mg isotope compositions, ranging from -1.14 to -0.67‰ of δ26MgDSM3 with an average of -0.85‰ (n=6), than that in the SHR, ranging from -1.34 to -0.74‰ of δ26MgDSM3 with an average of -1.15‰ (n=6). The river waters draining only carbonates have much lower δ26MgDSM3 values (-1.34 to -1.27‰, n=3), similar to other rivers draining carbonates. This implies that biological fractionation such as plant uptake would be limited because a geographical environment in the Han River basin is almost same. Mineral saturation indices indicate that the river waters are undersaturated with respect to primary and secondary minerals such as smectite but waters draining the carbonates are oversaturated with respect to calcite and dolomite. Hence, the lower δ26MgDSM3 values in the NHR relative to source rocks could be mainly attributed to the fractionation during silicate mineral dissolution. Contrary to the NHR, δ26MgDSM3 values in the SHR indistinguishable from those of the carbonates imply that carbonates dissolution/precipitation would not fractionate Mg isotopes. This study indicates that Mg isotopes could be used to constrain riverine Mg sources.

  17. Control of intragastric pH with omeprazole 20 mg, omeprazole 40 mg and lansoprazole 30 mg.

    PubMed

    Katz, P O; Xue, S; Castell, D O

    2001-05-01

    Single daily doses of proton pump inhibitors, omeprazole and lansoprazole provide effective acid suppression and equal healing and symptom relief in patients with GERD. Despite this, controversy exists as to the efficacy of available proton pump inhibitors in the control of gastric acidity. To assess the efficacy of omeprazole 20 mg vs. lansoprazole 30 mg and omeprazole 40 mg vs. lansoprazole 30 mg in intragastric pH control. Study I: 12 Helicobacter pylori-negative volunteers (mean age 33 years) were treated with omeprazole 20 mg and lansoprazole 30 mg in random order before breakfast for 7 days. Study II: 24 subjects (mean age 36 years) were similarly treated with omeprazole 40 mg and lansoprazole 30 mg for 7 days after a baseline pH study. One week washout was allowed between studies. Subjects had the same meal on each study day. On day seven, a 24-h intragastric pH study was performed. The percentage time for which gastric pH > 4 was analysed (Gastrosoft, Synectics Medical Inc.) and expressed as mean +/- s.d. (1) Omeprazole 20 mg and lansoprazole 30 mg showed no significant difference in the percentage time for which gastric pH > 4 in the daytime and night-time periods. (2) The percentage time for which pH > 4 with omeprazole 40 mg was significantly greater than lansoprazole 30 mg in both daytime (61 +/- 19% vs. 48 +/- 14%, P < 0.001), and night-time periods (34 +/- 21% vs. 26 +/- 14%, P < 0.05). (3) A large inter-subject variation existed in both studies. (4) In 10 subjects who participated in both studies, omeprazole 40 mg showed a significantly higher percentage time for which pH > 4 in the daytime (69 +/- 18% vs. 51 +/- 15%, P=0.015) than omeprazole 20 mg. These pH data support the therapeutic equivalency of FDA approved doses of omeprazole and lansoprazole.

  18. Agriculture, Forestry, Range Resources

    NASA Technical Reports Server (NTRS)

    Crea, W. J., Jr.

    1973-01-01

    Significant results obtained from ERTS-1 observations of agriculture, forestry, and range resources are summarized. Four major parts are covered: (1) crop classification and mensuration; (2) timber and range resources survey and classification; (3) soil survey and mapping; and (4) subdiscipline areas.

  19. Laser ranging data analysis

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Near real-time Lageos laser ranging data are analyzed in terms of range bias, time bias, and internal precision, and estimates for earth orientation parameters X(sub p), Y(sub p), and UT1 are obtained. The results of these analyses are reported in a variety of formats. Copies of monthly summaries from November, 1986 through November, 1987 are included.

  20. Long Range Facilities Planning

    DTIC Science & Technology

    1982-04-01

    Richard Muther range facilities Many alterna- analysis indi- cated that if NASSCO ever expected to surpass its output of the last several years, current...Marine Engineers (SNAME) SP-1 Panel Meeting. The Maritime Administration had Richard Muther (an authority on long range facility planning) address a

  1. Home range and travels

    USGS Publications Warehouse

    Stickel, L.F.; King, John A.

    1968-01-01

    The concept of home range was expressed by Seton (1909) in the term 'home region,' which Burr (1940, 1943) clarified with a definition of home range and exemplified in a definitive study of Peromyscus in the field. Burt pointed out the ever-changing characteristics of home-range area and the consequent absence of boundaries in the usual sense--a finding verified by investigators thereafter. In the studies summarized in this paper, sizes of home ranges of Peromyscus varied within two magnitudes, approximately from 0.1 acre to ten acres, in 34 studies conducted in a variety of habitats from the seaside dunes of Florida to the Alaskan forests. Variation in sizes of home ranges was correlated with both environmental and physiological factors; with habitat it was conspicuous, both in the same and different regions. Food supply also was related to size of home range, both seasonally and in relation to habitat. Home ranges generally were smallest in winter and largest in spring, at the onset of the breeding season. Activity and size also were affected by changes in weather. Activity was least when temperatures were low and nights were bright. Effects of rainfall were variable. Sizes varied according to sex and age; young mice remained in the parents' range until they approached maturity, when they began to travel more widely. Adult males commonly had larger home ranges than females, although there were a number of exceptions. An inverse relationship between population density and size of home range was shown in several studies and probably is the usual relationship. A basic need for activity and exploration also appeared to influence size of home range. Behavior within the home range was discussed in terms of travel patterns, travels in relation to home sites and refuges, territory, and stability of size of home range. Travels within the home range consisted of repeated use of well-worn trails to sites of food, shelter, and refuge, plus more random exploratory travels

  2. A Facile Approach Using MgCl2 to Formulate High Performance Mg2+ Electrolytes for Rechargeable Mg Batteries

    SciTech Connect

    Liu, Tianbiao L.; Shao, Yuyan; Li, Guosheng; Gu, Meng; Hu, Jian Z.; Xu, Suochang; Nie, Zimin; Chen, Xilin; Wang, Chong M.; Liu, Jun

    2014-01-01

    Rechargeable Mg batteries have been regarded as a viable battery technology for grid scale energy storage and transportation applications. However, the limited performance of Mg2+ electrolytes has been a primary technical hurdle to develop high energy density rechargeable Mg batteries. In this study, MgCl2 is demonstrated as a non-nucleophilic and cheap Mg2+ source in combining with Al Lewis acids (AlCl3, AlPh3 and AlEtCl2) to formulate a series of Mg2+ electrolytes characteristic of high oxidation stability (up to 3.4 V vs Mg), sulfur compatibility and electrochemical reversibility (up to 100% coulombic efficiency). Three electrolyte systems (MgCl2-AlCl3, MgCl2-AlPh3, and MgCl2-AlEtCl2) were prepared free of purification and fully characterized by multinuclear NMR (27Al{1H} and 25Mg{1H}) spectroscopies, single crystal X-ray diffraction, and electrochemical analysis. The reaction mechanism of MgCl2 and the Al Lewis acids in THF is discussed to highlight the formation of the electrochemically active [(µ-Cl)3Mg2(THF)6]+ monocation in these electrolytes. We are grateful for the financial support from the Pacific Northwest National Laboratory (PNNL)-Laboratory Directed Research and Development (LDRD) program for developing magnesium battery technology. The XRD and SEM data were collected at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is a multiprogram laboratory operated by Battelle Memorial Institute for the Department of Energy under Contract DE-AC05-76RL01830.

  3. Analgesic efficacy of acetaminophen 1000 mg, acetaminophen 2000 mg, and the combination of acetaminophen 1000 mg and codeine phosphate 60 mg versus placebo in acute postoperative pain.

    PubMed

    Skoglund, L A; Skjelbred, P; Fyllingen, G

    1991-01-01

    Acetaminophen (APAP) 1000 mg, APAP 2000 mg, the combination of APAP 1000 mg plus codeine phosphate 60 mg (APAPCOD), and placebo (PBO) were compared in a 6-hour, randomized, single-dose, double-blind, parallel-group analgesic trial. All active treatments were statistically superior (p less than 0.05) to placebo for 4 hours after medication with respect to pain intensity (PI) and pain intensity difference (PID), and up to 3 hours regarding pain relief (PAR). The combination scored better than all other treatments on the summary analgesic efficacy measures sum PI (SUMPI), sum PID (SPID), and total PAR (TOTPAR). The combination was statistically superior to APAP 1000 mg on SUMPI, TOTPAR and maximum PAR (MAXPAR). Acetaminophen 2000 mg showed marginal numerical superiority over 1000 mg for SUMPI, but was not statistically superior for any summary efficacy measure. The 2000-mg dose was numerically inferior to APAPCOD for every summary efficacy measure and statistically inferior regarding SPID and MAXPAR. We concluded that codeine 60 mg added to acetaminophen 1000 mg offers analgesic advantages, and acetaminophen reaches an analgesic ceiling effect at 1000 mg using the dental pain model.

  4. Inhibition of DNA ejection from bacteriophage by Mg+2 counterions

    NASA Astrophysics Data System (ADS)

    Lee, Sell; Tran, C. V.; Nguyen, T. T.

    2011-03-01

    The problem of inhibiting viral DNA ejection from bacteriophages by multivalent counterions, specifically Mg+2 counterions, is studied. Experimentally, it is known that MgSO4 salt has a strong and nonmonotonic effect on the amount of DNA ejected. There exists an optimal concentration at which the minimum amount of DNA is ejected from the virus. At lower or higher concentrations, more DNA is ejected from the capsid. We propose that this phenomenon is the result of DNA overcharging by Mg+2 multivalent counterions. As Mg+2 concentration increases from zero, the net charge of DNA changes from negative to positive. The optimal inhibition corresponds to the Mg+2 concentration where DNA is neutral. At lower/higher concentrations, DNA genome is charged. It prefers to be in solution to lower its electrostatic self-energy, which consequently leads to an increase in DNA ejection. By fitting our theory to available experimental data, the strength of DNA-DNA short range attraction energies, mediated by Mg+2, is found to be -0.004 kBT per nucleotide base. This and other fitted parameters agree well with known values from other experiments and computer simulations. The parameters are also in agreement qualitatively with values for tri- and tetravalent counterions.

  5. Inhibition of DNA ejection from bacteriophage by Mg^+2 counterions

    NASA Astrophysics Data System (ADS)

    Lee, Seil; Tran, Cathy V.; Nguyen, Toan T.

    2009-03-01

    The problem of inhibiting viral DNA ejection from bacteriophages by multivalent counterions, especially Mg^+2 counterions, is studied. Experimentally, it is known that MgSO4 salt has a strong and non-monotonic effect on the amount of DNA ejected. There exists an optimal concentration at which the least DNA is ejected from the virus. At lower or higher concentrations, more DNA is ejected from the capsid. We propose that this phenomenon is the result of DNA overcharging by Mg^+2 multivalent counterions. As Mg^+2 concentration increases from zero, DNA net charge changes from negative to positive. The optimal inhibition corresponds to the Mg^+2 concentration where DNA is neutral. At lower/higher concentrations, DNA genome is charged. It prefers to be in solution to lower its electrostatic self-energy, which consequently leads to an increase in DNA ejection. Our theory fits experimental data well. The strength of DNA-DNA short range attraction, mediated by Mg^+2, is found to be -0.003 kBT per nucleotide base.

  6. Superconducting MgB2 wires with vanadium diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hušek, I.; Kováč, P.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.; Szundiová, B.

    2017-10-01

    Single-core MgB2 wires with a vanadium barrier and Cu stabilization have been made by the in situ powder-in-tube (PIT) and internal magnesium diffusion (IMD) into boron processes. Heat treatment of PIT wires was done at the temperature range of 650 °C–850 °C/30 min. Critical currents of differently treated MgB2/V/Cu wires have been measured and related with the structure of MgB2. It was found that critical current density of MgB2/V wire annealed above 700 °C decreases rapidly. The obtained results clearly show that vanadium is a well formable metal and can be applied as an effective diffusion barrier for MgB2 wires heat-treated at temperatures ≤700 °C. This temperature limit is well applicable for MgB2 wires with high current densities made by PIT and also by the IMD process.

  7. TmMg and renal Mg threshold in normal man and in certain pathophysiologic conditions.

    PubMed

    Rude, R K; Ryzen, E

    1986-01-01

    The TmMg and renal Mg threshold were assessed in normal subjects and in a number of pathological conditions. The TmMg in normal subjects was 1.4 mg/100 ml glomerular filtrate (GF) 1.73 m2 and numerically equalled the renal Mg threshold of 1.4 mg/100 ml. No significant difference was seen in patients with primary hyperparathyroidism or hypoparathyroidism. Patients with familial hypocalciuric hypercalcemia, however, tended to have an elevated renal Mg threshold. Investigation of 3 patients with idiopathic renal Mg wasting demonstrated a normal TmMg but reduced renal Mg threshold. Urinary Mg excretion was also assessed in normomagnesemic alcoholic patients. Retention of a parenterally administered Mg load and renal Mg retention were significantly greater than normal despite normal serum Mg concentrations. These data suggest that determination of TmMg and renal Mg threshold may provide useful information in understanding Mg homeostasis in normal subjects and in disorders which may result in abnormal Mg metabolism.

  8. Range Safety Systems

    NASA Technical Reports Server (NTRS)

    Schrock, Kenneth W.; Humphries, Ricky H. (Technical Monitor)

    2002-01-01

    The high kinetic and potential energy of a launch vehicle mandates there be a mechanism to minimize possible damage to provide adequate safety for the launch facilities, range, and, most importantly, the general public. The Range Safety System, sometimes called the Flight Termination System or Flight Safety System, provides the required level of safety. The Range Safety System section of the Avionics chapter will attempt to describe how adequate safety is provided, the system's design, operation, and it's interface with the rest of the launch vehicle.

  9. Preliminary error budget for an optical ranging system: Range, range rate, and differenced range observables

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; Finger, M. H.

    1990-01-01

    Future missions to the outer solar system or human exploration of Mars may use telemetry systems based on optical rather than radio transmitters. Pulsed laser transmission can be used to deliver telemetry rates of about 100 kbits/sec with an efficiency of several bits for each detected photon. Navigational observables that can be derived from timing pulsed laser signals are discussed. Error budgets are presented based on nominal ground stations and spacecraft-transceiver designs. Assuming a pulsed optical uplink signal, two-way range accuracy may approach the few centimeter level imposed by the troposphere uncertainty. Angular information can be achieved from differenced one-way range using two ground stations with the accuracy limited by the length of the available baseline and by clock synchronization and troposphere errors. A method of synchronizing the ground station clocks using optical ranging measurements is presented. This could allow differenced range accuracy to reach the few centimeter troposphere limit.

  10. SNOWY RANGE WILDERNESS, WYOMING.

    USGS Publications Warehouse

    Houston, Robert S.; Bigsby, Philip R.

    1984-01-01

    A mineral survey of the Snowy Range Wilderness in Wyoming was undertaken and was followed up with more detailed geologic and geochemical surveys, culminating in diamond drilling of one hole in the Snowy Range Wilderness. No mineral deposits were identified in the Snowy Range Wilderness, but inasmuch as low-grade uranium and associated gold resources were identified in rocks similar to those of the northern Snowy Range Wilderness in an area about 5 mi northeast of the wilderness boundary, the authors conclude that the northern half of the wilderness has a probable-resource potential for uranium and gold. Closely spaced drilling would be required to completely evaluate this mineral potential. The geologic terrane precludes the occurrence of fossil fuels.

  11. The role of Mg in the crystallization of monohydrocalcite

    NASA Astrophysics Data System (ADS)

    Rodriguez-Blanco, Juan Diego; Shaw, Samuel; Bots, Pieter; Roncal-Herrero, Teresa; Benning, Liane G.

    2014-02-01

    Monohydrocalcite is a member of the carbonate family which forms in Mg-rich environments at a wide range of Mg/Ca ratios Mg2+aq/Ca2+aq≥0.17<65. Although found in modern sedimentary deposits and as a product of biomineralization, there is a lack of information about its formation mechanisms and about the role of Mg during its crystallization. In this work we have quantitatively assessed the mechanism of crystallization of monohydrocalcite through in situ synchrotron-based small and wide angle X-ray scattering (SAXS/WAXS) and off-line spectroscopic, microscopic and wet chemical analyses. Monohydrocalcite crystallizes via a 4-stage process beginning with highly supersaturated solutions from which a Mg-bearing, amorphous calcium carbonate (ACC) precursor precipitates. This precursor crystallizes to monohydrocalcite via a nucleation-controlled reaction in stage two, while in stage three it is further aged through Ostwald-ripening at a rate of 1.8 ± 0.1 nm/h1/2. In stage four, a secondary Ostwald ripening process (66.3 ± 4.3 nm/h1/2) coincides with the release of Mg from the monohydrocalcite structure and the concomitant formation of minor hydromagnesite. Our data reveal that monohydrocalcite can accommodate significant amounts of Mg in its structure (χMgCO3 = 0.26) and that its Mg content and dehydration temperature are directly proportional to the saturation index for monohydrocalcite (SIMHC) immediately after mixing the stock solutions. However, its crystallite and particle size are inversely proportional to these parameters. At high supersaturations (SIMHC = 3.89) nanometer-sized single crystals of monohydrocalcite form, while at low values (SIMHC = 2.43) the process leads to low-angle branching spherulites. Many carbonates produced during biomineralization form at similar conditions to most synthetic monohydrocalcites, and thus we hypothesize that some calcite or aragonite deposits found in the geologic record that have formed at high Mg/Ca ratios could be

  12. Mu-2 ranging

    NASA Technical Reports Server (NTRS)

    Martin, W. L.; Zygielbaum, A. I.

    1977-01-01

    The Mu-II Dual-Channel Sequential Ranging System designed as a model for future Deep Space Network ranging equipment is described. A list of design objectives is followed by a theoretical explanation of the digital demodulation techniques first employed in this machine. Hardware and software implementation are discussed, together with the details relating to the construction of the device. Two appendixes are included relating to the programming and operation of this equipment to yield the maximum scientific data.

  13. Estimating parasite host range.

    PubMed

    Dallas, Tad; Huang, Shan; Nunn, Charles; Park, Andrew W; Drake, John M

    2017-08-30

    Estimating the number of host species that a parasite can infect (i.e. host range) provides key insights into the evolution of host specialism and is a central concept in disease ecology. Host range is rarely estimated in real systems, however, because variation in species relative abundance and the detection of rare species makes it challenging to confidently estimate host range. We applied a non-parametric richness indicator to estimate host range in simulated and empirical data, allowing us to assess the influence of sampling heterogeneity and data completeness. After validating our method on simulated data, we estimated parasite host range for a sparsely sampled global parasite occurrence database (Global Mammal Parasite Database) and a repeatedly sampled set of parasites of small mammals from New Mexico (Sevilleta Long Term Ecological Research Program). Estimation accuracy varied strongly with parasite taxonomy, number of parasite occurrence records, and the shape of host species-abundance distribution (i.e. the dominance and rareness of species in the host community). Our findings suggest that between 20% and 40% of parasite host ranges are currently unknown, highlighting a major gap in our understanding of parasite specificity, host-parasite network structure, and parasite burdens. © 2017 The Author(s).

  14. Interstellar fossil Mg-26 and its possible relationship to excess meteoritic Mg-26

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.

    1986-01-01

    A plausible scenario is advanced for explainig a linear correlation found in some solar system solids between their Mg-26/Mg-24 isotopic ratios and their Al/Mg elemental abundance ratios. This scenario involves three stages: (1) the mechanical aggregation of an average ensemble of Al-bearing dust particles that is postulated to be modestly enriched in the Al/Mg abundance ratio because the aggregated particles themselves are; (2) the extraction, perhaps but not necessarily by hot distillation, of almost all Mg, leaving an aggregate with a large Al/Mg ratio and a large Mg-26 excess; and (3) the uptake of normal ambient Mg by the resulting hot Al-rich solid as it cools in Mg-rich vapor. A linear correlation in solids between their Mg-26/Mg-24 isotopic ratio and their aluminum enrichment may be a fossil correlation inherited from interstellar dust.

  15. Interstellar fossil Mg-26 and its possible relationship to excess meteoritic Mg-26

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.

    1986-01-01

    A plausible scenario is advanced for explainig a linear correlation found in some solar system solids between their Mg-26/Mg-24 isotopic ratios and their Al/Mg elemental abundance ratios. This scenario involves three stages: (1) the mechanical aggregation of an average ensemble of Al-bearing dust particles that is postulated to be modestly enriched in the Al/Mg abundance ratio because the aggregated particles themselves are; (2) the extraction, perhaps but not necessarily by hot distillation, of almost all Mg, leaving an aggregate with a large Al/Mg ratio and a large Mg-26 excess; and (3) the uptake of normal ambient Mg by the resulting hot Al-rich solid as it cools in Mg-rich vapor. A linear correlation in solids between their Mg-26/Mg-24 isotopic ratio and their aluminum enrichment may be a fossil correlation inherited from interstellar dust.

  16. Efficacy and Safety of Doxepin 1 mg, 3 mg, and 6 mg in Adults with Primary Insomnia

    PubMed Central

    Roth, Thomas; Rogowski, Roberta; Hull, Steven; Schwartz, Howard; Koshorek, Gail; Corser, Bruce; Seiden, David; Lankford, Alan

    2007-01-01

    Study Objectives: To evaluate the efficacy and safety of doxepin 1, 3, and 6 mg in insomnia patients. Design: Adults (18-64 y) with chronic primary insomnia (DSM-IV) were randomly assigned to one of four sequences of 1 mg, 3 mg, and 6 mg of doxepin, and placebo in a crossover study. Treatment periods consisted of 2 polysomnographic assessment nights with a 5-day or 12-day drug-free interval between periods. Efficacy was assessed using polysomnography (PSG) and patient-reported measures. Safety analyses included measures of residual sedation and adverse events. Measurements and Results: Sixty-seven patients were randomized. Wake time during sleep, the a priori defined primary endpoint, was statistically significantly improved at the doxepin 3 mg and 6 mg doses versus placebo. All three doses had statistically significant improvements versus placebo for PSG-defined wake after sleep onset, total sleep time, and overall sleep efficiency (SE). SE in the final third-of-the-night also demonstrated statistically significant improvement at all doses. The doxepin 6 mg dose significantly reduced subjective latency to sleep onset. All three doxepin doses had a safety profile comparable to placebo. There were no statistically significant differences in next-day residual sedation, and sleep architecture was generally clinically preserved. Conclusions: In adults with primary insomnia, doxepin 1 mg, 3 mg, and 6 mg was well-tolerated and produced improvement in objective and subjective sleep maintenance and duration endpoints that persisted into the final hour of the night. The side-effect profile was comparable to placebo, with no reported anticholinergic effects, no memory impairment, and no significant hangover/next-day residual effects. These data demonstrate that doxepin 1 mg, 3 mg, and 6 mg is efficacious in improving the sleep of patients with chronic primary insomnia. Citation: Roth T; Rogowski R; Hull S; Schwartz H; Koshorek G; Corser B; Seiden D. Efficacy and safety of

  17. A SIMS Calibration of Benthic Foraminiferal Mg/Ca

    NASA Astrophysics Data System (ADS)

    Curry, W. B.; Marchitto, T. M.

    2005-12-01

    Using a suite of multi-core tops, we have produced a calibration of C. pachyderma Mg/Ca versus temperature spanning the temperature range of 5 to 18 °C. The core tops are located along the Florida margin south of Dry Tortugas (KNR166), along the Bahamas west of Andros Island and Great Bahama Bank (KNR166), and along the southeastern margin of Brazil (KNR159). Water depths range from about 200 to 800 m for the Florida Straits multi-cores and 400 to 800 m for the Brazil margin multi-cores. Five of the KNR166 core tops contain post-1950 bomb radiocarbon with Fmodern> 1; several others have bomb radiocarbon mixed in with pre-bomb sediments to give ages less than 0 BP. Core top ages are generally older for the KNR159 multi-cores, but each is from a location with a well documented Holocene section. Sedimentation rates for KNR166 multi-cores vary from 10 to 100 cm kyr-1; for KNR159 multi-cores, sedimentation rates vary from 5 to 10 cm kyr-1. Elemental ratios were determined by Secondary Ionization Mass Spectrometry (SIMS) using a Cameca IMS 3f ion probe calibrated for Mg/Ca and Sr/Ca using two standards which were independently measured using ICP-MS. Using SIMS, the external precision of the calibration standards averages ±3.5% (1σ RSD) for Mg/Ca and ± 1.7% (1σ RSD) for Sr/Ca. SIMS elemental measurements were performed on one to three individual C. pachyderma tests in each core top; more than 30 tests have been measured from 18 multi-core tops. Mg/Ca variability within C. pachyderma tests averages ± 20% (1σ RSD) with a small but significant trend toward higher variability at higher Mg/Ca. Higher Mg/Ca is observed in warmer waters, but the Mg/Ca values are generally lower (at comparable warm temperatures) than observed in previous calibration studies. At temperatures below 8 °C, C. pachyderma Mg/Ca values are less than 2 mmole/mole. At temperatures warmer than 15 °C, C. pachyderma Mg/Ca values exceed 3 mmole/mole. The slope of Mg/Ca versus temperature (~0.14 mmole

  18. Laser Ranging Simulation Program

    NASA Technical Reports Server (NTRS)

    Piazolla, Sabino; Hemmati, Hamid; Tratt, David

    2003-01-01

    Laser Ranging Simulation Program (LRSP) is a computer program that predicts selected aspects of the performances of a laser altimeter or other laser ranging or remote-sensing systems and is especially applicable to a laser-based system used to map terrain from a distance of several kilometers. Designed to run in a more recent version (5 or higher) of the MATLAB programming language, LRSP exploits the numerical and graphical capabilities of MATLAB. LRSP generates a graphical user interface that includes a pop-up menu that prompts the user for the input of data that determine the performance of a laser ranging system. Examples of input data include duration and energy of the laser pulse, the laser wavelength, the width of the laser beam, and several parameters that characterize the transmitting and receiving optics, the receiving electronic circuitry, and the optical properties of the atmosphere and the terrain. When the input data have been entered, LRSP computes the signal-to-noise ratio as a function of range, signal and noise currents, and ranging and pointing errors.

  19. ATS-3 ranging support

    NASA Technical Reports Server (NTRS)

    Brisken, A. F.

    1977-01-01

    The purpose of this effort was to provide NASA-Goddard Space Flight Center with ATS-3 ranging data from ground stations of the VHF network and from an additional ground station installed at the NASA-Goddard Space Flight Center. Ranging measurements to the NASA transponder enabled calculation of the transponder's line-of-position. Installation of an S-band transponder at the same site and the conduct of ranging experiments to this transponder and others via ATS-6 provided a second line-of-position. The NASA S-band transponder was specifically designed for installation aboard spacecraft. Consequently, this program provided NASA an opportunity to compare two different techniques using geostationary satellites in the tracking low orbit satellites.

  20. EBSD analysis of MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Inoue, K.; Muralidhar, M.; Berger, K.; Noudem, J.

    2016-04-01

    The grain orientation, the texture and the grain boundary misorientations are important parameters for the understanding of the magnetic properties of the bulk MgB2 samples intended for super-magnet applications. Such data can be provided by electron backscatter diffraction (EBSD) analysis. However, as the grain size (GS) of the MgB2 bulks is preferably in the 100-200 nm range, the common EBSD technique working in reflection operates properly only on highly dense samples. In order to achieve a reasonably good Kikuchi pattern quality on all samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to several bulk MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analyzed within the SEM, operating with a specific sample holder. We present several EBSD mappings of samples prepared with different techniques and at various reaction temperatures.

  1. Collisional excitation of MgO by He

    NASA Astrophysics Data System (ADS)

    Mogren Al Mogren, M.; Ajili, Y.; Almania, S.; Ben Abdallah, D.; Hochlaf, M.

    2015-09-01

    Using a well-established ab initio methodology to generate the potential energy surface of the MgO-He interacting system and a quantum close-coupling treatment of nuclear motion, we give the rotational (de-)excitation cross-sections and the collision rate coefficients for the first 16 rotational levels of the MgO molecule and He for temperatures ranging from 10 up to 300 K. A clear propensity rule in favour of Δj = 1 rotational transitions is observed. These data are compared with previous works on astrophysical oxygen-bearing diatomic species. This work should be useful for the eventual detection of the key metal-oxide MgO molecule in the circumstellar and interstellar media with current and future high-resolution telescopes.

  2. Enhanced boron adsorption onto synthesized MgO nanosheets by ultrasonic method.

    PubMed

    Li, Ping; Liu, Chuang; Zhang, Li; Zheng, Shili; Zhang, Yi

    2017-01-01

    MgO nanosheets with high adsorption performance were fabricated by an ultrasonic method. It was revealed that, nest-like MgO was formed from the magnesium salt solution precipitation and further calcination. Then the nest-like MgO was exfoliated by ultrasonic waves to obtain MgO nanosheets with approximately a lateral of 200-600nm and a thickness of 10nm. Adjusting the ultrasonic time and power, the specific surface areas of MgO nanosheets could be tuned in a range of 79-168m(2)/g. The synthesized MgO nanosheets were used as adsorbents to remove boron from aqueous solution, and the maximum boron adsorption capacity of these MgO nanosheets reached 87mgg(-1). The high uptake capability of the MgO nanosheets makes it potentially adsorbent for the removal of boron from wastewaters.

  3. Antibacterial biodegradable Mg-Ag alloys.

    PubMed

    Tie, D; Feyerabend, F; Müller, W D; Schade, R; Liefeith, K; Kainer, K U; Willumeit, R

    2013-06-16

    The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4) and aging (T6) heat treatment. The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH)₂ and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7), revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231) and Staphylococcus epidermidis (DSMZ 3269), and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  4. Porous Mg formation upon dehydrogenation of MgH2 thin films

    NASA Astrophysics Data System (ADS)

    Dura, J. A.; Kelly, S. T.; Kienzle, P. A.; Her, J.-H.; Udovic, T. J.; Majkrzak, C. F.; Chung, C.-J.; Clemens, B. M.

    2011-05-01

    The hydrogenation and dehydrogenation of a thin film of Mg with a Pd cap layer was measured using neutron reflectometry. Upon hydrogenation, (at 373 K and 0.2 MPa H2), the Mg film swelled in the surface normal direction by an amount roughly equal to the difference in volume between MgH2 and Mg. After dehydrogenation (at 343-423 K), the Mg film returned to a composition of Mg but retained the swelled thickness by incorporating voids. The presence of the voids is confirmed by SEM micrographs. The voids may explain some of the changes in absorption kinetics after full cycling of Mg films.

  5. VENUS Ranging Study

    DTIC Science & Technology

    2014-12-01

    the two dimensional PECan modelling presented in the next section. The seamount at 30 km range from RC to CN has a significant effect on propagation...Gabriola Island there is an apparent ‘ seamount ’ in the bathymetry profiles of CN and EN at a range of 30 km from RC, see Figure 3. The sediment in the...region of the ‘ seamount ’ corresponds to the rock, gravel, and gravel and rock shown in Figure 5 intersecting each track off Gabriola Island. The

  6. Western Aeronautical Test Range

    NASA Technical Reports Server (NTRS)

    Sakahara, Robert D.

    2008-01-01

    This viewgraph presentation reviews the work of the Western Aeronautical Test Range (WATR). NASA's Western Aeronautical Test Range is a network of facilities used to support aeronautical research, science missions, exploration system concepts, and space operations. The WATR resides at NASA's Dryden Flight Research Center located at Edwards Air Force Base, California. The WATR is a part of NASA's Corporate Management of Aeronautical Facilities and funded by the Strategic Capability Asset Program (SCAP). Maps show the general location of the WATR area that is used for aeronautical testing and evaluation. The products, services and facilities of WATR are discussed,

  7. Himalayan Mountain Range, India

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Snow is present the year round in most of the high Himalaya Mountain Range (33.0N, 76.5E). In this view taken at the onset of winter, the continuous snow line can be seen for hundreds of miles along the south face of the range in the Indian states of Punjab and Kashmir. The snow line is at about 12,000 ft. altitude but the deep Cenab River gorge is easily delineated as a break along the south edge of the snow covered mountains. '

  8. Satellite Laser Ranging operations

    NASA Technical Reports Server (NTRS)

    Pearlman, Michael R.

    1994-01-01

    Satellite Laser Ranging (SLR) is currently providing precision orbit determination for measurements of: 1) Ocean surface topography from satellite borne radar altimetry, 2) Spatial and temporal variations of the gravity field, 3) Earth and ocean tides, 4) Plate tectonic and regional deformation, 5) Post-glacial uplift and subsidence, 6) Variations in the Earth's center-of-mass, and 7) Variations in Earth rotation. SLR also supports specialized programs in time transfer and classical geodetic positioning, and will soon provide precision ranging to support experiments in relativity.

  9. Broad host range plasmids.

    PubMed

    Jain, Aayushi; Srivastava, Preeti

    2013-11-01

    Plasmids are and will remain important cloning vehicles for biotechnology. They have also been associated with the spread of a number of diseases and therefore are a subject of environmental concern. With the advent of sequencing technologies, the database of plasmids is increasing. It will be of immense importance to identify the various bacterial hosts in which the plasmid can replicate. The present review article describes the features that confer broad host range to the plasmids, the molecular basis of plasmid host range evolution, and applications in recombinant DNA technology and environment.

  10. Analysis of the Deformation Behavior of Mg-RE and Mg-Li Alloys using In-situ Energy-dispersive Synchrotron X-ray Diffraction

    SciTech Connect

    Lentz, Martin; Clausen, Bjorn; Reimers, Walter

    2012-08-06

    EPSC-Model is able to predict the complex deformation behavior of Mg-RE and Mg-Li alloys within a wide range of strains. Modification of the texture by RE-elements and the addition of Li increases the activity of slip systems at low strains - Reorientation due to twinning is stretch over a larger range of plastic deformation. Deformation at high strains is realized mainly by the basal and the -pyramidal slip systems.

  11. Hydrogen storage systems from waste Mg alloys

    NASA Astrophysics Data System (ADS)

    Pistidda, C.; Bergemann, N.; Wurr, J.; Rzeszutek, A.; Møller, K. T.; Hansen, B. R. S.; Garroni, S.; Horstmann, C.; Milanese, C.; Girella, A.; Metz, O.; Taube, K.; Jensen, T. R.; Thomas, D.; Liermann, H. P.; Klassen, T.; Dornheim, M.

    2014-12-01

    The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)2 and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH4 + MgH2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes.

  12. Fire-Proof Evaluation of CaO Added Mg-3Al, Mg-6Al, and Mg-9Al Mg Cast Products

    NASA Astrophysics Data System (ADS)

    Lee, Jin-kyu; Kim, Shae K.

    Mg products are easily oxidized and burned when they are exposed to high temperature or fire by accident. In order to solve these problems, the fire-proof solution has been developed by adding CaO in Mg alloys. The fire-proof was evaluated by three methods: quantitative DTA for small sphere specimen, furnace ignition test for burrs and machined chips, and torch ignition test for products. DTA was carried out for obtaining quantitative ignition temperature data with respect to specimen geometry and test environment; the furnace ignition test for burr and chip ignition temperature data; and the torch test for ignition temperature data for manufactured products. This paper discusses the results of fire-proof properties of 1wt.%, and 1.5wt.% CaO added Mg-3Al, Mg-6Al, and Mg-9Al Mg alloys compared with other high temperature Mg alloys such as AE44, AS21, MRI153, and MRI230. Eco-Mg alloy will be low-cost and fire-proof Mg alloys for airplane and train applications in terms of preventing poisonous gas generation, inhalation bum, and ignition generation.

  13. Photodissociation of Mg +(NH 3) ion

    NASA Astrophysics Data System (ADS)

    Yoshida, Shinji; Okai, Nobuhiro; Fuke, Kiyokazu

    2001-10-01

    Electronically excited states of Mg +(NH 3) are studied by photodissociation after mass selection. The dissociation spectrum shows relatively sharp vibronic transitions centered at about 28 000 and 36 000 cm-1. These absorption bands are assigned to the 2P- 2S type transitions localized on the Mg + ion. In photodissociation, a photoinduced charge-transfer process to produce NH 3+ is observed in addition to evaporation and intracluster reaction processes to produce Mg + and MgNH 2+ ions, respectively. The mechanism for the production of these ions is discussed in terms of the predissociative and non-adiabatic interactions between the low-lying states.

  14. [Fluorescent probes for intracellular Mg2+ measurement].

    PubMed

    Komatsu, Hirokazu; Suzuki, Yoshio; Suzuki, Koji

    2004-08-01

    Recently, fluorescent probes are widely used as tools for dynamical measurement of ion distributions and concentrations in cells. They are highly sensitive, and offer imaging by the use of fluorescent microscopy in easily and less cell damaging way. This paper discusses the selectivity and optical character of the three novel Mg(2+) fluorescent probes. KMG-20AM offers ratiometric quantative measurement of Mg(2+), KMG-104 provides high-sensitive qualitative analysis and 3-D measurement. With those improved Mg(2+) fluorescent probes, the physiological and pathological role of Mg(2+) are going to be more and more clear.

  15. Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg2Si/MgB2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Ueno, Katsuya; Nagashima, Yukihito; Seto, Yusuke; Matsumoto, Megumi; Sakurai, Takahiro; Ohta, Hitoshi; Takahashi, Kazuyuki; Uchino, Takashi

    2016-07-01

    Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg2Si)/superconductor(MgB2) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg2Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB2 nanograins surrounded by the MgO/Mg2Si matrix. This transition is followed by the intergrain phase-lock transition at ˜24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.

  16. The Coordination of Mg in Foraminiferal Calcite

    NASA Astrophysics Data System (ADS)

    Branson, O.; Redfern, S. A.; Tyliszczak, T.; Sadekov, A.; Langer, G.; Elderfield, H.

    2012-12-01

    The Mg/Ca ratio in calcite shells ('tests') of foraminifera is an empirical ocean temperature proxy widely used to interpret palaeoclimates. We explore the distribution and local environment of Mg in foram tests using STXM and NEXAFS spectroscopy to test the fundamental assumptions behind the proxy, and shed light on the mechanisms underpinning this vital oceanographic tool. Throughout the development of the Mg/Ca proxy, it has been assumed that Mg in foraminifera tests substitutes directly into the calcite lattice (1). This assumption is based on XRD analyses of various high-Mg biogenic carbonates, where Mg concentrations are manifest in the shifted position of diffraction peaks (2, 3). The extrapolation of this trend to foraminiferal calcite links the proxy to inorganic precipitation experiments, and provides a theoretical mechanistic framework to understand the link between Mg/Ca and temperature: the substitution of Mg is endothermic, and favoured at higher temperatures. However, the concentration of Mg in most foraminifera (0-10 mmol/mol Mg/Ca) is below the detection limit of XRD methods, and the analogy to inorganic systems has not been explicitly tested. Electron microprobe (4-6), LA-ICP-MS (7) and high-resolution nanoSIMS mapping (Sadekov, unpub.) of foraminifera tests have revealed the presence of high 'trace element' bands running in plane with the test surface, enriched in Mg, Sr, S, organic molecules and other trace elements. This emphasises a key question highlighted by Dodd (1) when the proxy was still in its infancy: how is Mg incorporated into mineral skeletons? By direct substitution into the calcite lattice, interstitially in a separate distinct mineral phase, or associated with organic compounds? We address this fundamental question using scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy at ALS beamline 11.0.2 to examine the distribution and local atomic environment of Mg in two contrasting species of foraminifera

  17. Effect of organic ligands on Mg partitioning and Mg isotope fractionation during low-temperature precipitation of calcite

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; Immenhauser, Adrian; Buhl, Dieter; Purgstaller, Bettina; Baldermann, Andre; Dietzel, Martin

    2016-04-01

    Calcite growth experiments have been performed at 25 oC and 1 bar pCO2 in the presence of aqueous Mg and six organic ligands in the concentration range from 10-5 to 10-3 M. These experiments were performed in order to quantify the effect of distinct organic ligands on the Mg partitioning and Mg stable isotope fractionation during its incorporation in calcite at similar growth rates normalized to total surface area. The organic ligands used in this study comprise of (i) acetate acid, (ii) citrate, (iii) glutamate, (iv) salicylate, (v) glycine and (vi) ethylenediaminetetraacetic acid (EDTA), containing carboxyl- and amino-groups. These fuctional groups are required for bacterial activity and growth as well as related to biotic and abiotic mineralization processes occurring in sedimentary and earliest diagenetic aquatic environments (e.g. soil, cave, lacustrine, marine). The results obtained in this study indicate that the presence of organic ligands promotes an increase in the partition coefficient of Mg in calcite (DMg = (Mg/Ca)calcite (Mg/Ca)fluid). This behaviour can be explained by the temporal formation of aqueous Mg-ligand complexes that are subsequently adsorbed on the calcite surfaces and thereby reducing the active growth sites of calcite. The increase of DMg values as a function of the supersaturation degree of calcite in the fluid phase can be described by the linear equation LogDMg =0.3694 (±0.0329)×SIcalcite - 1.9066 (±0.0147); R2=0.92 In contrast, the presence of organic ligands, with exception of citrate, does not significantly affect the Mg isotope fractionation factor between calcite and reactive fluid (Δ26Mgcalcite-fluid = -2.5 ±0.1). Citrate likely exhibits larger fractionation between the Mg-ligand complexes and free aqueous Mg2+, compared to the other organic ligands studied in this work, as evidenced by the smaller Δ26Mgcalcite-fluid values. These results indicate that in Earth's surface calcite precipitating environments that are

  18. Agriculture, forest, and range

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The findings and recommendations of the panel for developing a satellite remote-sensing global information system in the next decade are reported. User requirements were identified in five categories: (1) cultivated crops, (2) land resources, (3)water resources, (4)forest management, and (5) range management. The benefits from the applications of satellite data are discussed.

  19. RADIO RANGING DEVICE

    DOEpatents

    Bogle, R.W.

    1960-11-22

    A description is given of a super-regenerative oscillator ranging device provided with radiating and receiving means and being capable of indicating the occurrence of that distance between itself and a reflecting object which so phases the received echo of energy of a preceding emitted oscillation that the intervals between oscillations become uniform.

  20. Institutional Long Range Planning.

    ERIC Educational Resources Information Center

    Caldwell Community Coll. and Technical Inst., Lenoir, NC.

    Long-range institutional planning has been in effect at Caldwell Community College and Technical Institute since 1973. The first step in the process was the identification of planning areas: administration, organization, educational programs, learning resources, student services, faculty, facilities, maintenance/operation, and finances. The major…

  1. Long Range Plan.

    ERIC Educational Resources Information Center

    Jefferson Coll., Hillsboro, MO.

    This document presents Jefferson College's "Long Range Plan," which is intended to provide the College's governing board, administration, and faculty and staff with a task-oriented blueprint for maximizing the delivery of higher education services to students and the community in a predictable, programmatic, and fiscally sound manner.…

  2. Himalayan Mountain Range

    NASA Image and Video Library

    1981-04-14

    STS001-12-350 (12-14 April 1981) --- India and China, the Ladokh and Zaskar Ranges of the Great Himalaya are clearly etched by snow and shadow. A detailed view shows the glaciation process over a wide area. Photo credit: NASA

  3. Agriculture, forestry, range resources

    NASA Technical Reports Server (NTRS)

    Crea, W. J.

    1974-01-01

    In the area of crop specie identification, it has been found that temporal data analysis, preliminary stratification, and unequal probability analysis were several of the factors that contributed to high identification accuracies. Single data set accuracies on fields of greater than 80,000 sq m (20 acres) are in the 70- to 90-percent range; however, with the use of temporal data, accuracies of 95 percent have been reported. Identification accuracy drops off significantly on areas of less than 80,000 sq m (20 acres) as does measurement accuracy. Forest stratification into coniferous and deciduous areas has been accomplished to a 90- to 95-percent accuracy level. Using multistage sampling techniques, the timber volume of a national forest district has been estimated to a confidence level and standard deviation acceptable to the Forest Service at a very favorable cost-benefit time ratio. Range specie/plant community vegetation mapping has been accomplished at various levels of success (69- to 90-percent accuracy). However, several investigators have obtained encouraging initial results in range biomass (forage production) estimation and range readiness predictions. Soil association map correction and soil association mapping in new area appear to have been proven feasible on large areas; however, testing in a complex soil area should be undertaken.

  4. Agriculture, forestry, range resources

    NASA Technical Reports Server (NTRS)

    Macdonald, R. B.

    1974-01-01

    The necessary elements to perform global inventories of agriculture, forestry, and range resources are being brought together through the use of satellites, sensors, computers, mathematics, and phenomenology. Results of ERTS-1 applications in these areas, as well as soil mapping, are described.

  5. Electric vehicles: Driving range

    NASA Astrophysics Data System (ADS)

    Kempton, Willett

    2016-09-01

    For uptake of electric vehicles to increase, consumers' driving-range needs must be fulfilled. Analysis of the driving patterns of personal vehicles in the US now shows that today's electric vehicles can meet all travel needs on almost 90% of days from a single overnight charge.

  6. Front Range Branch Officers

    NASA Astrophysics Data System (ADS)

    The Front Range Branch of AGU has installed officers for 1990: Ray Noble, National Center for Atmospheric Research, chair; Sherry Oaks, U.S. Geological Survey, chair-elect; Howard Garcia, NOAA, treasurer; Catharine Skokan, Colorado School of Mines, secretary. JoAnn Joselyn of NOAA is past chair. Members at large are Wallace Campbell, NOAA; William Neff, USGS; and Stephen Schneider, NCAR.

  7. Nonscanning confocal ranging system

    NASA Astrophysics Data System (ADS)

    Sun, P. C.; Arons, E.

    1995-03-01

    We demonstrate a nonscanning confocal ranging system based on spatially incoherent interferometry. Such a system has significant advantages over the conventional confocal imaging system and other interferometric systems. We develop the theory in terms of coherence cells and demonstrate the equivalence of our method to the conventional confocal methods. Experimental results are also provided.

  8. Fact Sheet: Range Complex

    NASA Technical Reports Server (NTRS)

    Cornelson, C.; Fretter, E.

    2004-01-01

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

  9. STDN ranging equipment

    NASA Technical Reports Server (NTRS)

    Jones, C. E.

    1975-01-01

    Final results of the Spaceflight Tracking and Data Network (STDN) Ranging Equipment program are summarized. Basic design concepts and final design approaches are described. Theoretical analyses which define requirements and support the design approaches are presented. Design verification criteria are delineated and verification test results are specified.

  10. Mobile satellite ranging

    NASA Technical Reports Server (NTRS)

    Silverberg, E. C.

    1978-01-01

    A brief review of the constraints which have limited satellite ranging hardware and an outline of the steps which are underway to improve the status of the equipment in this area are given. In addition, some suggestions are presented for the utilization of newer instruments and for possible future research and development work in this area.

  11. Space-Based Range

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Space-Based Range (SBR), previously known as Space-Based Telemetry and Range Safety (STARS), is a multicenter NASA proof-of-concept project to determine if space-based communications using NASA's Tracking and Data Relay Satellite System (TDRSS) can support the Range Safety functions of acquiring tracking data and generating flight termination signals, while also providing broadband Range User data such as voice, video, and vehicle/payload data. There was a successful test of the Range Safety system at Wallops Flight Facility (WFF) on December 20, 2005, on a two-stage Terrier-Orion spin-stabilized sounding rocket. SBR transmitted GPS tracking data and maintained links with two TDRSS satellites simultaneously during the 10-min flight. The payload section deployed a parachute, landed in the Atlantic Ocean about 90 miles downrange from the launch site, and was successfully recovered. During the Terrier-Orion tests flights, more than 99 percent of all forward commands and more than 95 percent of all return frames were successfully received and processed. The time latency necessary for a command to travel from WFF over landlines to White Sands Complex and then to the vehicle via TDRSS, be processed onboard, and then be sent back to WFF was between 1.0 s and 1.1 s. The forward-link margins for TDRS-10 (TDRS East [TDE]) were 11 dB to 12 dB plus or minus 2 dB, and for TDRS-4 (TDRS Spare [TDS]) were 9 dB to 10 dB plus or minus 1.5 dB. The return-link margins for both TDE and TDS were 6 dB to 8 dB plus or minus 3 dB. There were 11 flights on an F-15B at Dryden Flight Research Center (DFRC) between November 2006 and February 2007. The Range User system tested a 184-element TDRSS Ku-band (15 GHz) phased-array antenna with data rates of 5 Mbps and 10 Mbps. This data was a combination of black-and-white cockpit video, Range Safety tracking and transceiver data, and aircraft and antenna controller data streams. IP data formatting was used.

  12. Nanoscale order in ZnSe:(Mg, O)

    SciTech Connect

    Elyukhin, Vyacheslav A.

    2014-02-21

    Self-assembling of 1O4Mg identical tetrahedral clusters resulting in the nanoscale order in ZnSe:(Mg, O) is presented. Co-doping transforms ZnSe into Mg{sub x}Zn{sub 1−x}O{sub y}Se{sub 1−y} alloy of MgO, MgSe, ZnO and ZnSe. The decrease of a sum of the enthalpies of the constituent compounds and diminution of the strain energy are the causes of this phenomenon. The self-assembling conditions are obtained from the free energy minimum when magnesium and oxygen are in the dilute and ultra dilute limits, correspondingly. The occurrence of 1O4Mg clusters and completion of self-assembling when all oxygen atoms are in clusters are results of the continuous phase transitions. The self-assembling occurrence temperature does not depend on the oxygen content and it is a function of magnesium concentration. Mg{sub x}Zn{sub 1−x}O{sub y}Se{sub 1−y} with all oxygen atoms in clusters can be obtained in temperature ranges from T = 206 °C (x = 0.001, y = 1×10{sup −4}) to T = 456 °C (x = 0.01, y = 1×10{sup −4}) and from T = 237 °C (x = 0.001, y = 1×10{sup −6}) to T = 462 °C (x = 0.01, y = 1×10{sup −6})

  13. Differential Conductance Measurements of MgB2/I/Pb Heterojunctions and all-MgB2 Junctions

    NASA Astrophysics Data System (ADS)

    Cusick, David; Eckhardt, Matthew; Dai, Wenqing; Li, Qi; Chen, Ke; Cunnane, Daniel; Zhuang, C. G.; Xi, X. X.; Naito, Michio; Ramos, Roberto

    2015-03-01

    We present our work characterizing several types of Magnesium Diboride Josephson junctions, including MgB2/I/Pb heterojunctions and all-MgB2 junctions. We will report on the I-V and dI/dV-V data collected at various temperatures using both a cryocooler-based experimental platform between 2 and 20 Kelvin and using a 3He probe platform between 0.3 and 1.0 Kelvin. These were both developed by undergraduates in a liberal arts university. Using high-sampling rates with a 24-bit data acquisition card and access to a broad of range of temperatures, we track and report energy gap distributions and temperature-dependent features of dI/dV peaks of MgB2, comparing these with theoretical predictions. R.C.R. acknowledges support from National Science Foundation Grant # DMR-1206561.

  14. The puzzle of {sup 32}Mg

    SciTech Connect

    Fortune, H. T.

    2011-08-15

    An analysis of results of the {sup 30}Mg(t,p) {sup 32}Mg reaction demonstrates that the ground state is the normal state and the excited 0{sup +} state is the intruder, contrary to popular belief. Additional experiments are suggested.

  15. On the Incidence and Kinematics of Strong Mg II Absorbers

    NASA Astrophysics Data System (ADS)

    Prochter, Gabriel E.; Prochaska, Jason X.; Burles, Scott M.

    2006-03-01

    We present the results of two complementary investigations into the nature of strong (rest equivalent width, Wr>1.0 Å) Mg II absorption systems at high redshift. The first line of questioning examines the complete Sloan Digital Sky Survey Data Release 3 set of quasar spectra to determine the evolution of the incidence of strong Mg II absorption. This search resulted in 7421 confirmed Mg II systems of Wr>1.0 Å, yielding a >95% complete statistical sample of 4835 absorbers (systems detected in S/N>7 spectral regions) spanning a redshift range 0.35Mg(X), is characterized by a roughly constant value at z>0.8, indicating that the product of the number density and gas cross section of halos hosting strong Mg II is unevolving at these redshifts. In contrast, one observes a decline in lMg(X) at z<0.8, which we interpret as a decrease in the gas cross section to strong Mg II absorption and therefore a decline in the physical processes relevant to strong Mg II absorption. Perhaps uncoincidentally, this evolution roughly tracks the global evolution of the star formation rate density. Dividing the systems in Wr subsamples, the lMg(X) curves show similar shape with lower normalization at higher Wr values and a more pronounced decrease in lMg(X) at z<0.8 for larger Wr systems. We also present the results of a search for strong Mg II absorption in a set of 91 high-resolution quasar spectra collected on the ESI and HIRES spectrographs. These data allow us to investigate the kinematics of such systems at 0.81.0 Å were discovered. These systems are characterized by the presence of numerous components spread over an average velocity width of Δv~200 km s-1. Also, absorption due to more highly ionized species (e.g., Al III, C IV, Si IV) tends to display kinematic profiles similar to the corresponding Mg II and Fe II absorption. We consider all of these

  16. Magnesium isotopic compositions of the Mesoproterozoic dolostones: Implications for Mg isotopic systematics of marine carbonates

    NASA Astrophysics Data System (ADS)

    Huang, Kang-Jun; Shen, Bing; Lang, Xian-Guo; Tang, Wen-Bo; Peng, Yang; Ke, Shan; Kaufman, Alan J.; Ma, Hao-Ran; Li, Fang-Bing

    2015-09-01

    Available Mg isotope data indicate that dolostones of different ages have overlapping range of Mg isotopic composition (δ26Mg) and there is no systematic difference among different types of dolomites. To further explore the Mg isotopic systematics of dolomite formation, we measured Mg isotopic compositions of Mesoproterozoic dolostones from the Wumishan Formation in North China Block, because dolomite formation in Mesoproterozoic might have been fundamentally different from the younger counterparts. Based on petrographic observations, three texturally-different dolomite phases (dolomicrite, subhedral dolomite and anhedral dolomite) are recognized in the Wumishan dolostones. Nevertheless, these three types of dolomites have similar δ26Mg values, ranging from -1.35‰ to -1.72‰, which are indistinguishable from Neoproterozoic and Phanerozoic dolostones. To explain δ26Mg values of dolostones, we simulate the Mg isotopic system during dolomite formation by applying the one-dimensional Diffusion-Advection-Reaction (1D-DAR) model, assuming that the contemporaneous seawater is the Mg source of dolostone. The 1D-DAR modeling results indicate that the degree of dolomitization is controlled by sedimentation rate, seawater Mg concentration, temperature, and reaction rate of dolomite formation, whereas Mg isotopic composition of dolostone is not only dependent on these factors, but also affected by δ26Mg of seawater and isotope fractionation during dolomite formation. Moreover, the 1D-DAR model predicts that dolomite formation within sediments has limited range of variation in δ26Mg with respect to limestones. Furthermore, the modeling results demonstrate that dolostone is always isotopically heavier than Ca-carbonate precipitated from seawater, explaining the systematic isotopic difference between dolostones and limestones. Finally, we can infer from the 1D-DAR model that early-formed dolostone at shallower depth of sediments is always isotopically lighter than that

  17. Range expansion of mutualists

    NASA Astrophysics Data System (ADS)

    Muller, Melanie J. I.; Korolev, Kirill S.; Murray, Andrew W.; Nelson, David R.

    2012-02-01

    The expansion of a species into new territory is often strongly influenced by the presence of other species. This effect is particularly striking for the case of mutualistic species that enhance each other's proliferation. Examples range from major events in evolutionary history, such as the spread and diversification of flowering plants due to their mutualism with pollen-dispersing insects, to modern examples like the surface colonisation of multi-species microbial biofilms. Here, we investigate the spread of cross-feeding strains of the budding yeast Saccharomyces cerevisiae on an agar surface as a model system for expanding mutualists. Depending on the degree of mutualism, the two strains form distinctive spatial patterns during their range expansion. This change in spatial patterns can be understood as a phase transition within a stepping stone model generalized to two mutualistic species.

  18. Long range chromatin organization

    PubMed Central

    Acuña, Luciana I Gómez; Kornblihtt, Alberto R

    2014-01-01

    Splicing is a predominantly co-transcriptional process that has been shown to be tightly coupled to transcription. Chromatin structure is a key factor that mediates this functional coupling. In light of recent evidence that shows the importance of higher order chromatin organization in the coordination and regulation of gene expression, we discuss here the possible roles of long-range chromatin organization in splicing and alternative splicing regulation. PMID:25764333

  19. Light beam range finder

    DOEpatents

    McEwan, Thomas E.

    1998-01-01

    A "laser tape measure" for measuring distance which includes a transmitter such as a laser diode which transmits a sequence of electromagnetic pulses in response to a transmit timing signal. A receiver samples reflections from objects within the field of the sequence of visible electromagnetic pulses with controlled timing, in response to a receive timing signal. The receiver generates a sample signal in response to the samples which indicates distance to the object causing the reflections. The timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the reflection such that the time between transmission of pulses in the sequence in sampling by the receiver sweeps over a range of delays. The transmit timing signal causes the transmitter to transmit the sequence of electromagnetic pulses at a pulse repetition rate, and the received timing signal sweeps over the range of delays in a sweep cycle such that reflections are sampled at the pulse repetition rate and with different delays in the range of delays, such that the sample signal represents received reflections in equivalent time. The receiver according to one aspect of the invention includes an avalanche photodiode and a sampling gate coupled to the photodiode which is responsive to the received timing signal. The transmitter includes a laser diode which supplies a sequence of visible electromagnetic pulses. A bright spot projected on to the target clearly indicates the point that is being measured, and the user can read the range to that point with precision of better than 0.1%.

  20. Light beam range finder

    DOEpatents

    McEwan, T.E.

    1998-06-16

    A ``laser tape measure`` for measuring distance is disclosed which includes a transmitter such as a laser diode which transmits a sequence of electromagnetic pulses in response to a transmit timing signal. A receiver samples reflections from objects within the field of the sequence of visible electromagnetic pulses with controlled timing, in response to a receive timing signal. The receiver generates a sample signal in response to the samples which indicates distance to the object causing the reflections. The timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the reflection such that the time between transmission of pulses in the sequence in sampling by the receiver sweeps over a range of delays. The transmit timing signal causes the transmitter to transmit the sequence of electromagnetic pulses at a pulse repetition rate, and the received timing signal sweeps over the range of delays in a sweep cycle such that reflections are sampled at the pulse repetition rate and with different delays in the range of delays, such that the sample signal represents received reflections in equivalent time. The receiver according to one aspect of the invention includes an avalanche photodiode and a sampling gate coupled to the photodiode which is responsive to the received timing signal. The transmitter includes a laser diode which supplies a sequence of visible electromagnetic pulses. A bright spot projected on to the target clearly indicates the point that is being measured, and the user can read the range to that point with precision of better than 0.1%. 7 figs.

  1. Photometric Passive Range Sensor

    NASA Astrophysics Data System (ADS)

    Argueta-Diaz, Victor; García-Valenzuela, Augusto

    2008-04-01

    In this paper we present a passive optical ranging method that consists of taking several photometric measurements from the light radiated by an object and deriving the range from these measurements. This passive ranging device uses an iris of radius a, a lens of radius larger than a, and a photodetector of radius p

  2. Front Range Report, Abstracts

    NASA Astrophysics Data System (ADS)

    Spence, William

    The second regional conference of the Front Range Branch, AGU, was attended by more than 80 professionals and some 20 outstanding high school students. The conference included 2 days of interdisciplinary talks, and lots of discussion, that primarily were keyed to geophysical studies of Colorado, Wyoming, and New Mexico. Other talks reported on nonregional, and sometimes global, studies being done by geophypsicists of the Front Range region.Topics included tectonics of the Front Range and the Colorado Plateau, pollution of the Arkansas and Mississippi rivers, and a supreme polluting event that caused the late-Cretaceous extinctions. Other notable talks were on toxic cleanup, microburst (wind shear) detection at U.S. airports, and other meteorological studies. Several talks treated the audience to the excitement of new work and surprise discoveries. The meeting was multimedia, including the playing of two videos through a projection TV and the playing of a fascinating tape between an airport control tower and incoming pilots during a severe microburst event.

  3. Twinning-mediated formability in Mg alloys.

    PubMed

    Suh, Byeong-Chan; Kim, Jae H; Hwang, Ji Hyun; Shim, Myeong-Shik; Kim, Nack J

    2016-03-01

    Mg alloys are promising candidates for automotive applications due to their low density and high specific strength. However, their widespread applications have not been realized mainly because of poor formability at room temperature, arising from limited number of active deformation systems and strong basal texture. It has been recently shown that Mg-Zn-Ca alloys have excellent stretch formability, which has been ascribed to their weak basal texture. However, the distribution of basal poles is orthotropic, which might result in anisotropy during deformation and have adverse effect on formability. Here, we show that tension twinning is mainly responsible for enhanced formability of Mg-Zn-Ca alloys. We found that tension twinning is quite active during both uniaxial deformation and biaxial deformation of Mg-Zn-Ca alloy even under the stress conditions unfavourable for the formation of tensile twins. Our results provide new insights into the development of Mg alloys having high formability.

  4. Twinning-mediated formability in Mg alloys

    PubMed Central

    Suh, Byeong-Chan; Kim, Jae H.; Hwang, Ji Hyun; Shim, Myeong-Shik; Kim, Nack J.

    2016-01-01

    Mg alloys are promising candidates for automotive applications due to their low density and high specific strength. However, their widespread applications have not been realized mainly because of poor formability at room temperature, arising from limited number of active deformation systems and strong basal texture. It has been recently shown that Mg-Zn-Ca alloys have excellent stretch formability, which has been ascribed to their weak basal texture. However, the distribution of basal poles is orthotropic, which might result in anisotropy during deformation and have adverse effect on formability. Here, we show that tension twinning is mainly responsible for enhanced formability of Mg-Zn-Ca alloys. We found that tension twinning is quite active during both uniaxial deformation and biaxial deformation of Mg-Zn-Ca alloy even under the stress conditions unfavourable for the formation of tensile twins. Our results provide new insights into the development of Mg alloys having high formability. PMID:26926655

  5. Biogeochemical Mg cycle in the Barton Peninsula, King George Island, West Antarctica

    NASA Astrophysics Data System (ADS)

    Choi, H. B.; Ryu, J. S.; Lee, J.; Lim, H. S.; Yoon, H.

    2016-12-01

    Understanding of biogeochemical Mg cycle is important in terms of plant growth as well as global climate because Mg participates in numerous biogeochemical processes. Here, we collected rock, soil, water and moss samples in the Barton peninsula, King George Island, West Antarctica, and measured their elemental and Mg isotope compositions in order to quantify and understand the biogeochemical processes of the Mg cycle. Elemental results show that the input of seawater derived Mg mainly controls dissolved Mg in meltwater. Mg isotope compositions in rocks and soils are consistent within the error, -0.03 ± 0.15‰ (n=6) and +0.03 ± 0.07‰ (n=8), respectively. However, δ26Mg values of meltwater and moss are -0.69 ± 0.09‰ (n=34) and -0.46 ± 0.19‰ (n=16), respectively, indicating that mosses display higher δ26Mg values compared to meltwater they uptake. This implies an isotope fractionation in favor of heavy isotopes during moss growth. The apparent Mg isotope fractionation between moss and meltwater (Δ26Mgmoss-meltwater) ranges from 0.02‰ to 0.55‰, with an average of +0.29‰ (n=6), which is within the range previously reported during higher plant growth. Our finding suggests that enhanced plant growth in Arctic and Antarctica due to climate change and global warming may play an important role in the biogeochemical Mg cycle globally.

  6. Development of a cw Co : MgF 2 laser

    NASA Astrophysics Data System (ADS)

    Di Lieto, A.

    2003-03-01

    The results obtained in the development of a cryogenic cw Co : MgF 2 laser, realized at the Dipartimento di Fisica of the Università di Pisa are presented. The laser can be tuned continuously in the range between 1.6 and 2.1 μm, with a typical output power of 1-2 W. A preliminary application to the spectroscopy of a Tm : YLF doped crystal is reported by using a photoacoustic apparatus.

  7. Spinelloid phases in the system MgGa2O4-Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Barbier, J.; Hyde, B. G.

    1986-11-01

    Spinelloid phases have been observed and characterized by powder X-ray diffraction and high-resolution electron microscopy. Mg3Ga2GeO3(III), with a narrow composition range of approximately 3 mole percent Mg2GeO4, is stable at atmospheric pressure up to about 1,420° C, and is isostructural with β-Mg2SiO4 and the spinelloid Phase III of the NiAl2O4-Ni2SiO4 system. This represents the first occurrence of a β-phase structure stable at 1 atm pressure. Above 1,420° C (1 atm) Mg3Ga2GeO8 (III) decomposes reversibly into a mixture of spinel and olivine. At high pressure (around 30 kbar at 1,100° C) it transforms into another spinelloid phase, Mg3Ga2GeO8 (IV), isostructural with Phase IV of the NiAl2O4-Ni2SiO4 system. In terms of crystal structures and phase relations therefore there exists a close analogy between the magnesium gallo-germanate and nickel alumino-silicate systems, the former being a lower-pressure analogue of the latter. Our investigation of a number of other pseudo-binary spinel-olivine oxide systems suggests that the formation of spinelloid phases can be associated with the inverse character of the spinel component.

  8. The Dissolution Kinetics of MgO into CaO-MgO-Fe2O3 Slag

    NASA Astrophysics Data System (ADS)

    Wei, Ruirui; Lv, Xuewei; Yue, Zhiwen; Xiang, Shenglin

    2017-02-01

    Calcium ferrite is the main binding phase for high-basicity sinter. The production and structure of calcium ferrite greatly influence the quality of the sinter. With the change in gangue composition, MgO becomes an important factor in the generation of calcium ferrite. In this study, the rotating cylinder method was used to study the dissolution kinetics of MgO into CaO-MgO-Fe2O3 melt. The experimental variables included the temperature, the initial composition of the melt, the Fe2O3/CaO mass ratio, the rotation time, and the rotation speed. The results indicate that the dissolution rate increases with increasing dissolution time, temperature, and rotation speed but decreases with increasing MgO content and Fe2O3/CaO mass ratio in the initial slag. The dissolution rate was observed to increase and then decrease with the addition of SiO2 in the initial slag. The activation energy and diffusion coefficient for MgO dissolution were found to range from 117.31 to 234.24 kJ mol-1 and from 1.03 × 10-6 to 1.18 × 10-5 cm2 s-1, respectively. The concentration difference between the solid and liquid phases is the main driving force for dissolution, but the viscosity and magnesium ion diffusivity of the melt also affect the process.

  9. Efficacy and safety of 10-mg azilsartan compared with 8-mg candesartan cilexetil in Japanese patients with hypertension: a randomized crossover non-inferiority trial.

    PubMed

    Takahara, Mitsuyoshi; Shiraiwa, Toshihiko; Shindo, Megumi; Arai, Akie; Kusuda, Yuko; Katakami, Naoto; Kaneto, Hideaki; Matsuoka, Taka-Aki; Shimomura, Iichiro

    2014-09-01

    We investigated whether 10 mg per day of azilsartan, one-half of the normal dosage, would be non-inferior to 8 mg per day of candesartan cilexetil for controlling blood pressure in Japanese patients with hypertension. In this open-label, randomized, crossover trial, 309 hypertensive Japanese adults treated with 8-mg candesartan cilexetil were randomized into two arms and received either 10-mg azilsartan or 8-mg candesartan cilexetil in a crossover manner. The primary efficacy outcome was systolic blood pressure, and the margin of non-inferiority was set to be 2.5 mm Hg. The participants were 67±11 years old, and 180 (58%) were male. The baseline systolic and diastolic blood pressure levels were 127.1±13.2 and 69.7±11.2 mm Hg, respectively. During the study period, the difference in systolic blood pressure between the treatments with 10-mg azilsartan and 8-mg candesartan cilexetil was -1.7 mm Hg, with the two-sided 95% confidence interval (CI) ranged from -3.2 to -0.2 mm Hg. The upper boundary of the 95% CI was below the margin of 2.5 mm Hg, confirming the non-inferiority of 10-mg azilsartan to 8-mg candesartan cilexetil. The difference also reached significance (P=0.037). The corresponding difference in diastolic blood pressure was -1.4 (95% CI: -2.4 to -0.4) mm Hg (P=0.006). Treatment with 10-mg azilsartan was similar to 8-mg candesartan cilexetil in its association with rare adverse events. In conclusion, 10-mg azilsartan was non-inferior to 8-mg candesartan cilexetil for controlling systolic blood pressure in Japanese hypertensive patients already being treated with 8-mg candesartan cilexetil.

  10. Experimental 25Mg and 13C NMR and Computational Modeling Studies of Amorphous Mg-Ca Carbonates

    NASA Astrophysics Data System (ADS)

    Singer, J. W.; Yazaydin, A. O.; Kirkpatrick, R. J.; Saharay, M.; Bowers, G. M.

    2012-12-01

    Nuclear magnetic resonance (NMR) spectroscopy of synthetic Mg-Ca amorphous carbonates (AMC-ACC) provides direct, element specific structural information about these complicated phases. The 13C, 25Mg, and 43Ca resonances are typically broad and span the chemical shift ranges of all the crystalline polymorphs in the Ca-Mg-CO3-H2O system. In a fashion similar to our previous analysis of 43Ca NMR results for ACC,1 here we integrate new experimental 13C and 25Mg spectra obtained at 20T for samples with Mg/(Ca+Mg) ratios from x=0 to x=1 with quantum chemical calculations of the NMR parameters of the crystalline phases using CASTEP calculations, simulations of the spectra using the SIMPSON software, and classical molecular dynamics calculations. XRD and 13C NMR results are in general agreement with the one-phase/two-phase model of ACC-AMC derived from thermochemical work by others.2 13C-NMR spectra of amorphous materials having intermediate compositions can not be completely fit by mechanical mixing of ACC and AMC end members—requiring a degree of Ca/Mg solid solution. Amorphous samples in two-phase region crystallize to assemblages of dolomite-like (x~0.5) and hydromagnesite-like (x~1) defective structures, but we also observe aragonite co-nucleation in the presence of excess water, indicative of a more complex evolution. While 43Ca NMR of X-ray amorphous materials shows featureless, symmetric, Gaussian line shapes, the large quadrupole moment of 25Mg gives rise to superposition of several quadrupolar line shapes representing different local structural environments. Singularities of static Mg spectra are best explained by local environments similar to nequehonite, hydromagnesite, and landsfordite. The spectra can not exclude minor contributions from anhydrous phases dolomite, huntite, and magnesite. Additional sites having very large quadrupolar coupling and/or site asymmetry are not explained by any known reference phases. CITATIONS (1) Singer, J. W.; Yazaydin, A. O

  11. A major determinant for gliding motility in Mycoplasma genitalium: the interaction between the terminal organelle proteins MG200 and MG491.

    PubMed

    Martinelli, Luca; Lalli, Daniela; García-Morales, Luis; Ratera, Mercè; Querol, Enrique; Piñol, Jaume; Fita, Ignacio; Calisto, Bárbara M

    2015-01-16

    Several mycoplasmas, such as the emergent human pathogen Mycoplasma genitalium, developed a complex polar structure, known as the terminal organelle (TO), responsible for a new type of cellular motility, which is involved in a variety of cell functions: cell division, adherence to host cells, and virulence. The TO cytoskeleton is organized as a multisubunit dynamic motor, including three main ultrastructures: the terminal button, the electrodense core, and the wheel complex. Here, we describe the interaction between MG200 and MG491, two of the main components of the TO wheel complex that connects the TO with the cell body and the cell membrane. The interaction between MG200 and MG491 has a KD in the 80 nm range, as determined by surface plasmon resonance. The interface between the two partners was confined to the "enriched in aromatic and glycine residues" (EAGR) box of MG200, previously described as a protein-protein interaction domain, and to a 25-residue-long peptide from the C-terminal region of MG491 by surface plasmon resonance and NMR spectroscopy studies. An atomic description of the MG200 EAGR box binding surface was also provided by solution NMR. An M. genitalium mutant lacking the MG491 segment corresponding to the peptide reveals specific alterations in cell motility and cell morphology indicating that the MG200-MG491 interaction plays a key role in the stability and functioning of the TO.

  12. Magnesium (Mg) Retention and Mood Effects After Intravenous Mg Infusion in Premenstrual Dysphoric Disorder

    PubMed Central

    Khine, Khursheed; Rosenstein, Donald L.; Elin, Ronald J.; Niemela, Julie E.; Schmidt, Peter J.; Rubinow, David R.

    2006-01-01

    Background: Conflicting data exist regarding the presence of magnesium (Mg) deficiency and the therapeutic efficacy of Mg in premenstrual syndrome or premenstrual dysphoric disorder (PMDD). Methods: The % Mg retention was determined using 24-hour urinary Mg excretion and the total dose of Mg given intravenously. In women with (n = 17) and without (n = 14) prospectively diagnosed PMDD, several blood measures of Mg and mood were obtained before, immediately after, and the day following an intravenous Mg (.1 mmol/kg) loading dose. A positive mood response was seen under open conditions; as open Mg infusion improved mood, subsequent PMDD patients (n = 10) were randomized in a double-blind, placebo-controlled, crossover fashion. Results: Patients (31.5%) and control subjects (27.5%) retained comparable mean percentages of Mg. Neither group differed in measures of mean Mg before, immediately after, or the day following Mg infusion. Although there was a time effect for all mood measures in the patient group (p <.01 for all), there was neither a treatment nor time-by-treatment effect. Conclusions: Contrary to prior reports, we found no evidence of Mg deficiency in women with PMDD compared with control subjects. Furthermore, Mg was not superior to placebo in the mitigation of mood symptoms in women with PMDD. PMID:16197921

  13. Laser Range Camera Modeling

    SciTech Connect

    Storjohann, K.

    1990-01-01

    This paper describes an imaging model that was derived for use with a laser range camera (LRC) developed by the Advanced Intelligent Machines Division of Odetics. However, this model could be applied to any comparable imaging system. Both the derivation of the model and the determination of the LRC's intrinsic parameters are explained. For the purpose of evaluating the LRC's extrinsic parameters, i.e., its external orientation, a transformation of the LRC's imaging model into a standard camera's (SC) pinhole model is derived. By virtue of this transformation, the evaluation of the LRC's external orientation can be found by applying any SC calibration technique.

  14. Mechanism and regulation of Mg-chelatase.

    PubMed Central

    Walker, C J; Willows, R D

    1997-01-01

    Mg-chelatase catalyses the insertion of Mg into protoporphyrin IX (Proto). This seemingly simple reaction also is potentially one of the most interesting and crucial steps in the (bacterio)chlorophyll (Bchl/Chl)-synthesis pathway, owing to its position at the branch-point between haem and Bchl/Chl synthesis. Up until the level of Proto, haem and Bchl/Chl synthesis share a common pathway. However, at the point of metal-ion insertion there are two choices: Mg2+ insertion to make Bchl/Chl (catalysed by Mg-chelatase) or Fe2+ insertion to make haem (catalysed by ferrochelatase). Thus the relative activities of Mg-chelatase and ferrochelatase must be regulated with respect to the organism's requirements for these end products. How is this regulation achieved? For Mg-chelatase, the recent design of an in vitro assay combined with the identification of Bchl-biosynthetic enzyme genes has now made it possible to address this question. In all photosynthetic organisms studied to date, Mg-chelatase is a three-component enzyme, and in several species these proteins have been cloned and expressed in an active form. The reaction takes place in two steps, with an ATP-dependent activation followed by an ATP-dependent chelation step. The activation step may be the key to regulation, although variations in subunit levels during diurnal growth may also play a role in determining the flux through the Bchl/Chl and haem branches of the pathway. PMID:9359397

  15. Magnesium isotopic composition of the oceanic mantle and oceanic Mg cycling

    NASA Astrophysics Data System (ADS)

    Liu, Ping-Ping; Teng, Fang-Zhen; Dick, Henry J. B.; Zhou, Mei-Fu; Chung, Sun-Lin

    2017-06-01

    To constrain the Mg isotopic composition of the oceanic mantle, investigate Mg isotope fractionation of abyssal peridotites during seafloor alteration, and assess Mg budget in the oceans, a suite of 32 abyssal peridotite samples from the Gakkel Ridge and Southwest Indian Ridge (SWIR) was, for the first time, selected for high-precision Mg isotope analyses. Although most of these samples are extensively altered, largely by serpentinization and weathering, primary olivine, diopside and enstatite grains are preserved in some samples. Olivine grains from the least altered samples have δ26Mg varying from -0.30 to -0.12‰ (n = 7), whereas enstatite and diopside have δ26Mg varying from -0.27 to -0.16‰ (n = 7), and from -0.23 to -0.09‰ (n = 6), respectively. Whole-rock δ26Mg values range from -0.24 to 0.03‰ with an average of -0.12 ± 0.13‰ (2SD, n = 32). Strongly serpentinized peridotites have lower average δ26Mg values (δ26Mg = -0.19 ± 0.07‰, 2SD, n = 7) than weathering-dominated ones (δ26Mg = -0.10 ± 0.12‰, 2SD, n = 25). Calculated Mg isotopic compositions of fresh mantle peridotites vary from -0.29 to -0.13‰, beyond the previously reported range of the subcontinental lithospheric mantle (-0.25 ± 0.04‰) and the analytical uncertainty (±0.07‰, 2SD). Our study therefore indicates that the oceanic mantle may have similar but slightly heterogeneous Mg isotopic compositions to that of subcontinental lithospheric mantle. Secondary serpentinization does not fractionate Mg isotopes of abyssal peridotites, whereas low-T weathering and formation of clay can result in the enrichment of heavy Mg isotopes in abyssal peridotites. This study also demonstrates that fluid-rock interaction does not necessarily produce rocks with intermediate Mg isotopic compositions. Magnesium isotopes of the rocks thereafter are dependent on the secondary minerals formed. We also conclude that the release of light Mg isotopes into the ocean during alteration of abyssal

  16. Monocular visual ranging

    NASA Astrophysics Data System (ADS)

    Witus, Gary; Hunt, Shawn

    2008-04-01

    The vision system of a mobile robot for checkpoint and perimeter security inspection performs multiple functions: providing surveillance video, providing high resolution still images, and providing video for semi-autonomous visual navigation. Mid-priced commercial digital cameras support the primary inspection functions. Semi-autonomous visual navigation is a tertiary function whose purpose is to reduce the burden of teleoperation and free the security personnel for their primary functions. Approaches to robot visual navigation require some form of depth perception for speed control to prevent the robot from colliding with objects. In this paper present the initial results of an exploration of the capabilities and limitations of using a single monocular commercial digital camera for depth perception. Our approach combines complementary methods in alternating stationary and moving behaviors. When the platform is stationary, it computes a range image from differential blur in the image stack collected at multiple focus settings. When the robot is moving, it extracts an estimate of range from the camera auto-focus function, and combines this with an estimate derived from angular expansion of a constellation of visual tracking points.

  17. Western Aeronautical Test Range

    NASA Technical Reports Server (NTRS)

    Sakahara, Robert D.

    2008-01-01

    NASA's Western Aeronautical Test Range (WATR) is a network of facilities used to support aeronautical research, science missions, exploration system concepts, and space operations. The WATR resides at NASA's Dryden Flight Research Center located at Edwards Air Force Base, California. The WATR is a part of NASA's Corporate Management of Aeronautical Facilities and funded by the Strategic Capability Asset Program (SCAP). It is managed by the Aeronautics Test Program (ATP) of the Aeronautics Research Mission Directorate (ARMD) to provide the right facility at the right time. NASA is a tenant on Edwards Air Force Base and has an agreement with the Air Force Flight Test Center to use the land and airspace controlled by the Department of Defense (DoD). The topics include: 1) The WATR supports a variety of vehicles; 2) Dryden shares airspace with the AFFTC; 3) Restricted airspace, corridors, and special use areas are available for experimental aircraft; 4) WATR Products and Services; 5) WATR Support Configuration; 6) Telemetry Tracking; 7) Time Space Positioning; 8) Video; 9) Voice Communication; 10) Mobile Operations Facilities; 11) Data Processing; 12) Mission Control Center; 13) Real-Time Data Analysis; and 14) Range Safety.

  18. Range Process Simulation Tool

    NASA Technical Reports Server (NTRS)

    Phillips, Dave; Haas, William; Barth, Tim; Benjamin, Perakath; Graul, Michael; Bagatourova, Olga

    2005-01-01

    Range Process Simulation Tool (RPST) is a computer program that assists managers in rapidly predicting and quantitatively assessing the operational effects of proposed technological additions to, and/or upgrades of, complex facilities and engineering systems such as the Eastern Test Range. Originally designed for application to space transportation systems, RPST is also suitable for assessing effects of proposed changes in industrial facilities and large organizations. RPST follows a model-based approach that includes finite-capacity schedule analysis and discrete-event process simulation. A component-based, scalable, open architecture makes RPST easily and rapidly tailorable for diverse applications. Specific RPST functions include: (1) definition of analysis objectives and performance metrics; (2) selection of process templates from a processtemplate library; (3) configuration of process models for detailed simulation and schedule analysis; (4) design of operations- analysis experiments; (5) schedule and simulation-based process analysis; and (6) optimization of performance by use of genetic algorithms and simulated annealing. The main benefits afforded by RPST are provision of information that can be used to reduce costs of operation and maintenance, and the capability for affordable, accurate, and reliable prediction and exploration of the consequences of many alternative proposed decisions.

  19. MiniAERCam Ranging

    NASA Technical Reports Server (NTRS)

    Talley, Tom

    2003-01-01

    Johnson Space Center (JSC) is designing a small, remotely controlled vehicle that will carry two color and one black and white video cameras in space. The device will launch and retrieve from the Space Vehicle and be used for remote viewing. Off the shelf cellular technology is being used as the basis for communication system design. Existing plans include using multiple antennas to make simultaneous estimates of the azimuth of the MiniAERCam from several sites on the Space Station and use triangulation to find the location of the device. Adding range detection capability to each of the nodes on the Space Vehicle would allow an estimate of the location of the MiniAERCam to be made at each Communication And Telemetry Box (CATBox) independent of all the other communication nodes. This project will investigate the techniques used by the Global Positioning System (GPS) to achieve accurate positioning information and adapt those strategies that are appropriate to the design of the CATBox range determination system.

  20. Nano-cube MgO formed on silicon substrate using pulsed laser deposition.

    PubMed

    Kaneko, Satoru; Ito, Takeshi; Akiyama, Kensuke; Yasui, Manabu; Hirabayashi, Yasuo; Soga, Masayasu; Miyake, Yumiko; Yoshimoto, Mamoru

    2012-03-01

    Nano-cube MgO particles were formed on Si substrates by deposition of an MgO target using pulsed laser deposition method. An epitaxial film grows on Si(001) substrate with its contraction of lattice constants. In this study, expecting high quality MgO film, the MgO film prepared in the oxygen pressure ranging from 75-400 mTorr at the high temperature of -750 degrees C. The deposited MgO showed the growth of (001) preferred orientation on the Si(001) substrate. However, X-ray Photoelectron Spectroscopy (XPS) indicated the MgO film did not form a continuous film on the Si surface. Interestingly, the surface morphology observed by an Atomic Force Microscopy (AFM) showed nano-cube MgO particles scattered on the smooth surface of Si substrate. After annealing the nano-cube MgO, the shape of MgO particles were changed from nano-cube to round shaped particles. The AFM image of the surface showed round shaped MgO nanoparticles scattered on rough surface. X-ray Diffraction (XRD) revealed the epitaxial growth of MgO(001) with cubic on cubic arrangement on the Si(001) substrate (MgO[100] parallel to Si[100]).

  1. Scratch Adhesion Evaluation of Electroless Nickel Plating on mg and mg Alloys

    NASA Astrophysics Data System (ADS)

    Liu, Zhenmin; Gao, Wei

    Magnesium (Mg) and its alloys are being used as structural components in industry because of their high strength-to-weight ratio and relatively high stiffness. A shortcoming of Mg based alloys is their poor corrosion and wear resistance. Therefore, coatings or surface treatment are needed for protection purpose. This paper reports our work on electroless plating of Ni-P on Mg alloys. Pure Mg, AZ31 and AZ91 Mg alloys were used as the substrates to investigate friction and adhesion properties of the electroless Ni-P coatings. The maximum friction coefficient (~0.3) was found on the electroless nickel coating of pure Mg substrate. The adhesion strengths of the coatings on AZ31 and AZ91 Mg alloys are higher than that on pure Mg. The critical load (a measure of adhesion strength) of AZ31 reached 13.1 N.

  2. Synthesis, structural and hydrogenation properties of Mg-rich MgH2-TiH2 nanocomposites prepared by reactive ball milling under hydrogen gas.

    PubMed

    Cuevas, Fermin; Korablov, Dmytro; Latroche, Michel

    2012-01-21

    MgH(2)-TiH(2) nanocomposites have been obtained by reactive ball milling of elemental powders under 8 MPa of hydrogen pressure. The composites consist of a mixture of β-rutile MgH(2), γ-orthorhombic high pressure MgH(2) and ε-tetragonal TiH(2) phases with nanosized crystallites ranging from 4 to 12 nm. In situ hydrogen absorption curves on milling reveal that nanocomposite formation occurs in less than 50 min through the consecutive synthesis of the TiH(2) and MgH(2) phases. The abrasive and catalytic properties of TiH(2) speed up the formation of the MgH(2) phase. Thermodynamic, kinetic and cycling hydrogenation properties have been determined for the 0.7MgH(2)-0.3TiH(2) composite and compared to nanometric MgH(2). Only the MgH(2) phase desorbs hydrogen reversibly at moderate temperature (523 to 598 K) and pressure (10(-3) to 1 MPa). The presence of TiH(2) does not modify the thermodynamic properties of the Mg/MgH(2) system. However, the MgH(2)-TiH(2) nanocomposite exhibits outstanding kinetic properties and cycling stability. At 573 K, H-sorption takes place in less than 100 s. This is 20 times faster than for a pure nanometric MgH(2) powder. We demonstrate that the TiH(2) phase inhibits grain coarsening of Mg, which allows extended nucleation of the MgH(2) phase in Mg nanoparticles before a continuous and blocking MgH(2) hydride layer is formed. The low crystallinity of the TiH(2) phase and its hydrogenation properties are also compatible with a gateway mechanism for hydrogen transfer from the gas phase to Mg. Mg-rich MgH(2)-TiH(2) nanocomposites are an excellent media for hydrogen storage at moderate temperatures.

  3. Narrowband filters for the FUV range

    NASA Astrophysics Data System (ADS)

    Rodríguez-de Marcos, Luis; Larruquert, Juan I.; Méndez, José A.; Aznárez, José A.; Fu, Liping

    2015-05-01

    We address the design, fabrication, and characterization of transmittance filters for the Ionosphere Photometer instrument (IP), developed by the Center for Space Science and Applied Research (CSSAR). IP, a payload of Feng-Yun 3D meteorological satellite, to be launched on 2016, is aimed to perform photometry measurements of Earth's ionosphere by the analysis of the OI (135.6 nm) spectral line and N2 Lyman-Birge-Hopfield (LBH, 140-180 nm) band, both of them in the far ultraviolet (FUV) range. The most convenient procedure to isolate a spectral band is the use of tunable transmittance filters. In many applications the intensity of the ultraviolet, visible and infrared background is higher than the intensity of the target FUV lines; therefore one of the most important requirements for transmittance filters is to reject (by reflecting and/or by absorbing) as efficiently as possible the visible and close ranges. In the FUV range, (Al/MgF2)n transmittance filters are the most common, and they are suitable to reject the visible and adjacent ranges. These materials present unique properties in this range: MgF2 is transparent down to ˜115 nm and Al has a very low refractive index in the FUV that contrasts well with MgF2. Narrowband tunable filters with very low transmittance at long wavelengths are achievable. The main data on the preparation and characterization of IP filters by Grupo de Óptica de Láminas Delgadas (GOLD) is detailed. In this proceeding we present (Al/MgF2)3 filters peaked at either 135.6 nm or at the center of the LBH band (˜160 nm). Filters were characterized in the 125-800 nm range (143-800 nm range for the LBH filter). After some storage in a desiccator, both coatings kept a transmittance of ~0.14 at their target wavelengths, with visible-to-peak transmittance ratios of 1.2·10-4 (OI filter) and 1.3·10-4 (LBH filter). One filter tuned at each target wavelength was exposed to ~300 Gy 60Co gamma dose, with no significant transmittance change.

  4. In vitro and in vivo comparison of binary Mg alloys and pure Mg.

    PubMed

    Myrissa, Anastasia; Agha, Nezha Ahmad; Lu, Yiyi; Martinelli, Elisabeth; Eichler, Johannes; Szakács, Gábor; Kleinhans, Claudia; Willumeit-Römer, Regine; Schäfer, Ute; Weinberg, Annelie-Martina

    2016-04-01

    Biodegradable materials are under investigation due to their promising properties for biomedical applications as implant material. In the present study, two binary magnesium (Mg) alloys (Mg2Ag and Mg10Gd) and pure Mg (99.99%) were used in order to compare the degradation performance of the materials in in vitro to in vivo conditions. In vitro analysis of cell distribution and viability was performed on discs of pure Mg, Mg2Ag and Mg10Gd. The results verified viable pre-osteoblast cells on all three alloys and no obvious toxic effect within the first two weeks. The degradation rates in in vitro and in vivo conditions (Sprague-Dawley® rats) showed that the degradation rates differ especially in the 1st week of the experiments. While in vitro Mg2Ag displayed the fastest degradation rate, in vivo, Mg10Gd revealed the highest degradation rate. After four weeks of in vitro immersion tests, the degradation rate of Mg2Ag was significantly reduced and approached the values of pure Mg and Mg10Gd. Interestingly, after 4 weeks the estimated in vitro degradation rates approximate in vivo values. Our systematic experiment indicates that a correlation between in vitro and in vivo observations still has some limitations that have to be considered in order to perform representative in vitro experiments that display the in vivo situation.

  5. Range imaging laser radar

    DOEpatents

    Scott, M.W.

    1990-06-19

    A laser source is operated continuously and modulated periodically (typically sinusoidally). A receiver imposes another periodic modulation on the received optical signal, the modulated signal being detected by an array of detectors of the integrating type. Range to the target determined by measuring the phase shift of the intensity modulation on the received optical beam relative to a reference. The receiver comprises a photoemitter for converting the reflected, periodically modulated, return beam to an accordingly modulated electron stream. The electron stream is modulated by a local demodulation signal source and subsequently converted back to a photon stream by a detector. A charge coupled device (CCD) array then averages and samples the photon stream to provide an electrical signal in accordance with the photon stream. 2 figs.

  6. Range imaging laser radar

    DOEpatents

    Scott, Marion W.

    1990-01-01

    A laser source is operated continuously and modulated periodically (typicy sinusoidally). A receiver imposes another periodic modulation on the received optical signal, the modulated signal being detected by an array of detectors of the integrating type. Range to the target determined by measuring the phase shift of the intensity modulation on the received optical beam relative to a reference. The receiver comprises a photoemitter for converting the reflected, periodically modulated, return beam to an accordingly modulated electron stream. The electron stream is modulated by a local demodulation signal source and subsequently converted back to a photon stream by a detector. A charge coupled device (CCD) array then averages and samples the photon stream to provide an electrical signal in accordance with the photon stream.

  7. The Mg impurity in nitride alloys

    SciTech Connect

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R.; Koleske, D. D.; Allerman, A. A.; Wang, Ke; Araki, Tsutomu; Nanishi, Yasushi

    2014-02-21

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  8. Examining the Evidence for the Influence of Carbonate Saturation State on Benthic Foraminiferal Mg/Ca

    NASA Astrophysics Data System (ADS)

    Martin, P. A.; Lea, D. W.; McCorkle, D. C.

    2002-12-01

    Benthic foraminiferal Mg/Ca paleothermometry is based on an empirical relationship between the Mg/Ca of benthic foraminifera recovered from core tops and in situ bottom water temperatures (Rosenthal, 1997; Martin et al, in press; Lear et al, in review). While there is a tight correlation between shell Mg/Ca and temperature over a broad range of temperatures (-1 to 20 degrees C), Mg/Ca variation over the small range of deep water temperatures reveals departures from the calibration curve at low temperatures. Lower Mg/Ca values are generally associated with the deepest sites from the Atlantic and Pacific, contributing to an apparently steeper Mg/Ca-T response for abyssal benthics. The steeper response of abyssal benthics may reflect an influence of decreasing carbonate saturation with depth. Saturation related effects have already been documented for Mg in planktonic foraminifera and for other metals (Cd, Ba, and Zn) in benthic foraminifera shells (see Marchitto and ref. therein). Although it is difficult to definitively separate the effects of various environmental parameters (including temperature, depth, and relative saturation states), which often change in unison, we can use the core top Mg/Ca data to estimate the potential influence of saturation state. An alternative calibration of the benthic Mg/Ca - T relationship can be derived from core top benthic foraminifera based only on sites bathed in waters above carbonate saturation that yields a slightly smaller change in Mg/Ca per degree C (~9.5% vs. 11%) but better explains benthic Mg/Ca from the coldest sites (-1degrees C). Using this alternative Mg/Ca -T relation and a subset of data from the Ceara Rise and Ontong Java Plateau, we can estimate a maximum Mg/Ca offset attributable to saturation state. By comparing core top and downcore data, we can also address possible differences in the primary Mg-T response and carbonate saturation related effects between different genera (Cibicidoides and Uvigerina).

  9. Prussian Blue Mg-Li Hybrid Batteries.

    PubMed

    Sun, Xiaoqi; Duffort, Victor; Nazar, Linda F

    2016-08-01

    The major advantage of Mg batteries relies on their promise of employing an Mg metal negative electrode, which offers much higher energy density compared to graphitic carbon. However, the strong coulombic interaction of Mg(2+) ions with anions leads to their sluggish diffusion in the solid state, which along with a high desolvation energy, hinders the development of positive electrode materials. To circumvent this limitation, Mg metal negative electrodes can be used in hybrid systems by coupling an Li(+) insertion cathode through a dual salt electrolyte. Two "high voltage" Prussian blue analogues (average 2.3 V vs Mg/Mg(2+); 3.0 V vs Li/Li(+)) are investigated as cathode materials and the influence of structural water is shown. Their electrochemical profiles, presenting two voltage plateaus, are explained based on the two unique Fe bonding environments. Structural water has a beneficial impact on the cell voltage. Capacities of 125 mAh g(-1) are obtained at a current density of 10 mA g(-1) (≈C/10), while stable performance up to 300 cycles is demonstrated at 200 mA g(-1) (≈2C). The hybrid cell design is a step toward building a safe and high density energy storage system.

  10. Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation.

    PubMed

    Martinez Sanchez, Adela H; Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine; Weinberg, Annelie; Luthringer, Bérengère J C

    2017-03-01

    Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10wt% of gadolinium (Mg-10Gd) and Mg with 2wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Bioequivalence of ondansetron oral soluble film 8 mg (ZUPLENZ) and ondansetron orally disintegrating tablets 8 mg (ZOFRAN) in healthy adults.

    PubMed

    Dadey, Eric

    2015-01-01

    Oral formulations of ondansetron are used to prevent nausea and vomiting associated with chemotherapy, radiotherapy, and surgery. An oral soluble film formulation of ondansetron (OND OSF) was developed using MonoSol Rx's proprietary PharmFilm technology and was formulated to dissolve rapidly on the tongue, without the need for water. This product provides an oral antiemetic treatment option for patients who experience difficulty swallowing. The purpose of this study was to compare the bioequivalence of OND OSF 8 mg (ZUPLENZ, Monosol Rx, Warren, NJ) with ondansetron orally disintegrating tablets (OND ODT) 8 mg (ZOFRAN, GlaxoSmithKline, Research Triangle Park). In 3 individual open-label, randomized studies, healthy adult subjects received a single dose of OND OSF 8 mg and a single dose of OND ODT 8 mg, under fasted conditions (study 1, n = 48), fed conditions (study 2, n = 48), and fasted with and without water (study 3, n = 18). Each dosing period was followed by a 3- or 7-day washout period. Ondansetron pharmacokinetics were assessed predose to 24 hours postdose for the single 8-mg doses of OND OSF and OND ODT. All analyses were conducted on natural log-transformed pharmacokinetic parameters for OND OSF and OND ODT. Under both fasted and fed conditions, the 90% confidence interval for the comparisons of OND OSF and OND ODT plasma ondansetron area under the curve from time 0 to the last measured concentration (AUC0-t), area under the concentration vs. time curve from time 0 to infinity (AUC0-∞), and maximum plasma concentration (Cmax) were within the 80%-125% range, indicating bioequivalence between the formulations. With features designed to make it portable and easy to take, OND OSF 8 mg provides an alternative treatment option, particularly for patients with dysphagia and others who find it difficult to take oral tablets.

  12. Controlled release of ibuprofen using Mg Al LDH nano carrier

    NASA Astrophysics Data System (ADS)

    Dasgupta, Sudip

    2017-08-01

    In the present study, NSAID (non-steroidal anti-inflammatory drugs) such as ibuprofen in anionic form has been intercalated in-situ into the interlayer space of Mg Al LDH nanoparticle during co-precipitation of hydroxides. LDH nanohybrids are characterized by XRD, FTIR and UV spectroscopy. Mg1-xAlx(NO3)x(OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Ibuprofen was intercalated in inter layer space of Mg-Al LDH during coprecipitation of drug LDH conjugate in nitrogen atmosphere. The nanopowders synthesised were in the size range between 25 to 90 nm with an average particle size of 55 nm. XRD analysis proved that there is an increase in d003 spacing from 7.89 Å for pristine LDH to 14.71 Å for ibuprofen intercalated LDH due to the intercalation of bigger ibuprofen molecule in the interlayer space of LDH. FTIR analysis showed hydroxyl and carbonyl stretching of ibuprofen in LDH-IBU sample confirming the intercalation of ibuprofen in the interlayer structure of LDH. The drug release study in phosphate buffer solution at pH 7.4 using UV-Vis spectroscopy demonstrated that 50 % drug molecules were released in 15 hours and more than 85 % release was achieved after 36 hours.

  13. MgCaO Dry Etching on GaN

    NASA Astrophysics Data System (ADS)

    Hlad, M.; Ren, F.

    2005-11-01

    MgCaO films grown by rf plasma-assisted Molecular Beam Epitaxy and capped with Sc2O3 are promising candidates as surface passivation layers and gate dielectrics on GaN-based high electron mobility transistors (HEMTs) and metal-oxide semiconductor HEMTs (MOS-HEMTs) respectively. Two different plasma chemistries were examined for etching these thin films on GaN. Inductively Coupled Plasmas of CH4/H2/Ar produced etch rates only in the range 20-70 å/min, comparable to the Ar sputter rates under the same conditions. Similarly slow MgCaO etch rates (˜100 å/min) were obtained with Cl2/Ar discharges under the same conditions, but GaN showed rates almost an order of magnitude higher. The MgCaO removal rates are limited by the low volatilities of the respective etch products. The CH4/H2/Ar plasma chemistry produced a selectivity of around 2 or etching the MgCaO with respect to GaN.

  14. The influence of Mg-Zr master alloy microstructure on the corrosion of Mg

    NASA Astrophysics Data System (ADS)

    Gandel, D. S.; Easton, M. A.; Gibson, M. A.; Abbott, T.; Birbilis, N.

    In this study, sixteen Mg-Zr alloys were produced to investigate the role of Zr on corrosion of Mg. Alloys were produced using two different commercial Mg-Zr master alloys commonly used for grain refining Mg, but which contain different Zr particle size distributions. It is seen that the master alloy with a smaller Zr particle size leads to an alloy containing more Zr in solid solution. The ratio of Zr in solid solution and in particle form was observed to have a marked effect on the corrosion of Mg.

  15. Is Mg-stabilized amorphous calcium carbonate a homogeneous mixture of amorphous magnesium carbonate and amorphous calcium carbonate?

    PubMed

    Yang, Sheng-Yu; Chang, Hsun-Hui; Lin, Cang-Jie; Huang, Shing-Jong; Chan, Jerry C C

    2016-10-04

    We find two types of carbonate ions in Mg stabilized amorphous calcium carbonate (Mg-ACC), whose short-range orders are identical to those of ACC and amorphous magnesium carbonate (AMC). Mg-ACC comprises a homogeneous mixture of the nano-clusters of ACC and AMC. Their relative amount varies systematically at different pH.

  16. Ultrafast Synthesis and Related Phase Evolution of Mg2Si and Mg2Sn Compounds

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Lu, Qiangbing; Yan, Yonggao; Su, Xianli; Tang, Xinfeng

    2017-02-01

    Both Mg2Si and Mg2Sn compounds were synthesized by an ultra-fast self-propagating high-temperature synthesis (SHS) method. The data regarding SHS were obtained via theoretical calculation combined with experiments, showing that the adiabatic temperature T ad and ignition temperature T ig of Mg2Si are a little higher than those of Mg2Sn. The mechanism of phase evolution and the concomitant microstructure evolution during the synthesis process of Mg2Si and Mg2Sn compounds were investigated by adopting SHS technique coupled with a sudden quenching treatment. Differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), and x-ray powder diffraction (XRD) results indicate that Mg2Si compound can be directly synthesized through the reaction of Mg and Si elements at around 850 K. Correspondingly, the formation of Mg2Sn needs to undergo melting of Sn and the subsequent feeble reaction between Mg and Sn elements before the large scale transformation at 730 K. As the groundwork, this research embodies great significance for future study on the ultrafast SHS process of the ternary Mg2Si1-x Sn x solid solutions.

  17. Neutron range spectrometer

    DOEpatents

    Manglos, Stephen H.

    1989-06-06

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are collimnated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. The computer solves the following equation in the analysis: ##EQU1## where: N(x).DELTA.x=the number of neutron interactions measured between a position x and x+.DELTA.x, A.sub.i (E.sub.i).DELTA.E.sub.i =the number of incident neutrons with energy between E.sub.i and E.sub.i +.DELTA.E.sub.i, and C=C(E.sub.i)=N .sigma.(E.sub.i) where N=the number density of absorbing atoms in the position sensitive counter means and .sigma. (E.sub.i)=the average cross section of the absorbing interaction between E.sub.i and E.sub.i +.DELTA.E.sub.i.

  18. Spontaneously intermixed Al-Mg barriers enable corrosion-resistant Mg/SiC multilayer coatings

    DOE PAGES

    Soufli, Regina; Fernandez-Perea, Monica; Baker, Sherry L.; ...

    2012-07-24

    Magnesium/silicon carbide (Mg/SiC) has the potential to be the best-performing reflective multilayercoating in the 25–80 nm wavelength region but suffers from Mg-related corrosion, an insidious problem which completely degrades reflectance. We have elucidated the origins and mechanisms of corrosion propagation within Mg/SiC multilayers. Based on our findings, we have demonstrated an efficient and simple-to-implement corrosion barrier for Mg/SiC multilayers. In conclusion, the barrier consists of nanometer-scale Mg and Al layers that intermix spontaneously to form a partially amorphous Al-Mg layer and is shown to prevent atmospheric corrosion while maintaining the unique combination of favorable Mg/SiC reflective properties.

  19. Formation and Corrosion Resistance of Mg-Al Hydrotalcite Film on Mg-Gd-Zn Alloy

    NASA Astrophysics Data System (ADS)

    Ba, Z. X.; Dong, Q. S.; Kong, S. X.; Zhang, X. B.; Xue, Y. J.; Chen, Y. J.

    2017-06-01

    An environment-friendly technique for depositing a Mg-Al hydrotalcite (HT) (Mg6Al2(OH)16-CO3ṡ4H2O) conversion film was developed to protect the Mg-Gd-Zn alloy from corrosion. The morphology and chemical compositions of the film were analyzed by scanning electronic microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy (RS), respectively. The electrochemical test and hydrogen evolution test were employed to evaluate the biocorrosion behavior of Mg-Gd-Zn alloy coated with the Mg-Al HT film in the simulated body fluid (SBF). It was found that the formation of Mg-Al HT film was a transition from amorphous precursor to a crystalline HT structure. The HT film can effectively improve the corrosion resistance of magnesium alloy. It indicates that the process provides a promising approach to modify Mg-Gd-Zn alloy.

  20. Mg deficiency affects leaf Mg remobilization and the proteome in Brassica napus.

    PubMed

    Billard, Vincent; Maillard, Anne; Coquet, Laurent; Jouenne, Thierry; Cruz, Florence; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain; Etienne, Philippe

    2016-10-01

    In order to cope with variable mineral nutrient availability, higher plants have developed numerous strategies including the remobilization of nutrients from source to sink tissues. However, such processes remain relatively unknown for magnesium (Mg), which is the third most important cation in plant tissues. Using Mg depletion of Brassica napus, we have demonstrated that Mg is remobilized from old leaves to young shoot tissues. Moreover, this study showed that Mg depletion induces modification of nutrient uptake, especially Zn and Mn. Finally, comparative proteomic analysis of old leaves (source of Mg) revealed amongst other results that some proteins requiring Mg for their functionality (isocitrate dehydrogenase for example) were up-regulated. Moreover, down-regulation of proteases suggested that mobilization of Mg from old leaves was not associated with senescence.

  1. Mg-isotopic fractionation in the manila clam (Ruditapes philippinarum): New insights into Mg incorporation pathway and calcification process of bivalves

    NASA Astrophysics Data System (ADS)

    Planchon, Frédéric; Poulain, Céline; Langlet, Denis; Paulet, Yves-Marie; André, Luc

    2013-11-01

    We estimate the magnesium stable isotopic composition (δ26Mg) of the major compartments involved in the biomineralisation process of euryhaline bivalve, the manila clam Ruditapes philippinarum. Our aim is to identify the fractionation processes associated with Mg uptake and its cycling/transport in the bivalve organism, in order to better assess the controlling factors of the Mg isotopic records in bivalve shells. δ26Mg were determined in seawater, in hemolymph, extrapallial fluid (EPF), soft tissues and aragonitic shell of adult clams collected along the Auray River estuary (Gulf of Morbihan, France) at two sites showing contrasted salinity regimes. The large overall δ26Mg variations (4.16‰) demonstrate that significant mass-dependent Mg isotopic fractionations occur during Mg transfer from seawater to the aragonitic shell. Soft tissues span a range of fractionation factors relative to seawater (Δ26Mgsoft tissue-seawater) of 0.42 ± 0.12‰ to 0.76 ± 0.12‰, and show evidence for biological isotopic fractionation of Mg. Hemolymph and EPF are on average isotopically close to seawater (Δ26Mghemolymph-seawater = -0.20 ± 0.27‰; 2 sd; n = 5 and Δ26MgEPF-seawater = -0.23 ± 0.25‰; 2 sd; n = 5) indicating (1) a predominant seawater origin for Mg in the intercellular medium and (2) a relatively passive transfer route through the bivalve organism into the calcifying fluid. The lightest isotopic composition is found in shell, with δ26Mg ranging from -1.89 ± 0.07‰ to -4.22 ± 0.06‰. This range is the largest in the dataset and is proposed to result from a combination of abiotic and biologically-driven fractionation processes. Abiotic control includes fractionation during precipitation of aragonite and accounts for Δ26Mgaragonite-seawater ≈ 1000 ln αaragonite-seawater = -1.13 ± 0.28‰ at 20 °C based on literature data. Deviations from inorganic precipitate (expressed as Δ26MgPhysiol) appear particularly variable in the clam shell, ranging from 0

  2. Interlayer exchange coupling, dipolar coupling and magnetoresistance in Fe/MgO/Fe trilayers with a subnanometer MgO barrier

    NASA Astrophysics Data System (ADS)

    Kozioł-Rachwał, A.; Skowroński, W.; Frankowski, M.; Chęciński, J.; Ziętek, S.; Rzeszut, P.; Ślęzak, M.; Matlak, K.; Ślęzak, T.; Stobiecki, T.; Korecki, J.

    2017-02-01

    Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 ÅMgO<6 Å. The coupling was enhanced for the trilayer grown on a homoepitaxial MgO buffer layer, and its IEC constant was estimated to be -3.3 erg/cm2 at a MgO thickness of 2.7 Å. After magnetic characterization, the sample was patterned into circular-shaped pillars with diameters ranging from 200 nm to 520 nm. We showed that the dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers, and we determined dependence of the dipolar coupling on the pillar diameter. Finally, magnetoresistance (MR) was measured as a function of MgO thickness (dMgO), and a non-zero MR was found for the MgO as thin as 3.4 Å. Extrapolation of the MR (dMgO) dependence to MR=0 allowed us to determine the length of the pinholes in our sample, which was estimated to be (3.2±0.5) Å.

  3. Toward accurate thermochemistry of the (24)MgH, (25)MgH, and (26)MgH molecules at elevated temperatures: corrections due to unbound states.

    PubMed

    Szidarovszky, Tamás; Császár, Attila G

    2015-01-07

    The total partition functions QT and their first two moments Q(')T and Q(″)T, together with the isobaric heat capacities CpT, are computed a priori for three major MgH isotopologues on the temperature range of T = 100-3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro)vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to QT at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q(″)T and CpT, principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of (24)MgH, (25)MgH, and (26)MgH at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species.

  4. Reactive wetting of amorphous silica by molten Al-Mg alloys and their interfacial structures

    NASA Astrophysics Data System (ADS)

    Shi, Laixin; Shen, Ping; Zhang, Dan; Jiang, Qichuan

    2016-07-01

    The reactive wetting of amorphous silica substrates by molten Al-Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO2 surface was 115° while that for pure Mg was 35° at 1073 K. For the Al-Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al-Mg alloy on the SiO2 surface was mainly attributed to the formation of Mg2Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

  5. AB Initio Characterization of MgCCH, MgCCH(+), and MgC2, and Pathways to their Formation in the Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Woon, David E.

    1996-01-01

    A study of Mg-bearing compounds has been performed in order to determine molecular properties which are critical for planning new astronomical searches and laboratory studies. The primary focus of the work is on MgCCH, MgCCH(+), and the isomers of MgC2. Only MgCCH has been identified in laboratory studies. Additional calculations have been carried out on MgH, MgNC, MgCN, and their cations in an effort to evaluate pathways to the formation of MgCCH and MgCCH(+) in the InterStellar Medium (ISM) or in circumstellar envelopes. Correlated ab initio methods and correlation-consistent basis sets have been employed. Properties including structures, rotational constants, dipole moments, and harmonic frequencies are reported. A transition state between linear MgCC and cyclic MgC2 has been characterized and was found to yield a minimal barrier (approx. 0.5 kcal/mole), indicating easy interconversion to the cyclic form. Direct reactions in the ISM between Mg or Mg(+) and HCCH are precluded by energetic considerations, but a number of ion- molecule or neutral-neutral exchange reactions between CCH and various Mg-containing species offer plausible pathways to MgCCH or MgCCH(+). Weakly bound MgH may react with CCH to form MgCCH, but MgH has not been detected. Both MgNC and MgCN have been observed, but reactions with CCH are slightly endothermic by 1-3 kcal/mole. Although MgH(+), MgNC(+), and MgCN(+) have not been detected, their reactions with CCH to form MgCCH(+) are all exothermic. With only a small barrier separating linear MgCC and cyclic MgC2, the dissociative recombination of MgCCH(+) with an electron is expected to yield cyclic MgC2, and regenerate Mg and CCH. New astronomical searches for MgCCH, MgCCH(+), cyclic MgC2, MgNC(+), and MgCN(+) will provide further insight into organo-magnesium astrochemistry.

  6. Diffusion of Al dimers on the surface of Mg clusters

    NASA Astrophysics Data System (ADS)

    Dai, Xiongying; Yang, Jianyu; Hu, Wangyu; Liu, Yanhui

    2017-06-01

    The surface diffusion of Al dimmers on Mg clusters with hexahedral structure was studied using the combination of quenched molecular dynamics and the embedded atom method. The system energy barriers of typical minimum energy diffusion paths for Al dimers on the Mg clusters were calculated using the Nudged Elastic Band method. In our study range (153-4061 atoms), the binding energies on the (0001) facets and the (1{\\overline 1 }01) facets differed, the binding energy on the former was lower than that on the latter. Moreover, cluster size only slightly influenced the binding energy values. Two possible diffusion paths were studied. Results showed that the diffusion of the dimer on the (0001) facet easily occurred at low temperatures. Furthermore, the interaction between the two atoms of the dimer facilitated the dimer crossing of the step edge between the (1{\\overline 1 }01) facets by hopping mechanism.

  7. Observation of pseudogap in MgB2.

    PubMed

    Patil, Swapnil; Medicherla, V R R; Ali, Khadiza; Singh, Ravi Shankar; Manfrinetti, Pietro; Wrubl, F; Dhar, Sudesh Kumar; Maiti, Kalobaran

    2017-09-06

    We investigate the electronic structure of a specially prepared highly dense conventional high temperature superconductor, MgB2 employing high resolution photoemission spectroscopy. The spectral evolution close to the Fermi energy is commensurate to BCS descriptions as expected. However, the spectra in the wider energy range reveal emergence of a pseudogap much above the superconducting transition temperature indicating apparent departure from the BCS scenario. The energy scale of the pseudogap is comparable to the energy of E2g phonon mode responsible for superconductivity in MgB2 and the pseudogap can be attributed to the effect of electron-phonon coupling on the electronic structure. These results reveal a scenario of the emergence of the superconducting gap within an electron-phonon coupling induced pseudogap and have significant implication in the study of high temperature superconductors. © 2017 IOP Publishing Ltd.

  8. Magnetic flux noise in MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Khare, Neeraj; Singh, D. P.; Gupta, Ajai K.

    2008-05-01

    Magnetic flux noise in MgB2 polycrystalline sample is measured using a high-TC rf-superconducting quantum interference device in the temperature range of 6-40K. A small magnetic field (˜200mG ) was applied while cooling the sample. The flux noise exhibits 1/fα type of behavior with α ˜1.0-1.3 and shows enhanced noise around 24 and 37K. The flux noise seems to originate from thermally activated vortex hopping. The large magnetic noise at 24K indicates the presence of larger density of pinning sites with energies ˜0.061eV leading to enhanced magnetic fluctuations at temperatures much below TC.

  9. COSMIC DUST IN Mg II ABSORBERS

    SciTech Connect

    Menard, Brice; Fukugita, Masataka

    2012-08-01

    Mg II absorbers induce reddening on background quasars. We measure this effect and infer the cosmic density of dust residing in these systems to be {Omega} Almost-Equal-To 2 Multiplication-Sign 10{sup -6}, in units of the critical density of the universe, which is comparable to the amount of dust found in galactic disks or about half the amount inferred to exist outside galaxies. We also estimate the neutral hydrogen abundance in Mg II clouds to be {Omega} Almost-Equal-To 1.5 Multiplication-Sign 10{sup -4}, which is approximately 5% of hydrogen in stars in galaxies. This implies a dust-to-gas mass ratio for Mg II clouds of about 1/100, which is similar to the value for normal galaxies. This would support the hypothesis of the outflow origin of Mg II clouds, which are intrinsically devoid of stars and hence have no sources of dust. Considerations of the dust abundance imply that the presence of Mg II absorbers around galaxies lasts effectively for a few Gyr. High-redshift absorbers allow us to measure the rest-frame extinction curve to 900 A, at which the absorption by the Lyman edge dominates over scattering by dust in the extinction opacity.

  10. Epitaxial MgO/Fe(001) and Fe/MgO(001): Structures of the interfaces

    NASA Astrophysics Data System (ADS)

    Młyńczak, E.; Freindl, K.; Spiridis, N.; Korecki, J.

    2013-01-01

    The chemical, electronic and magnetic structures of the interfaces between Fe(001) and MgO(001) thin films were studied using conversion electron Mössbauer spectroscopy (CEMS). A 1 ML thick 57Fe probe located at either of the interfaces in the MgO/56Fe/MgO epitaxial structure enabled precise measurements of the interfacial hyperfine interactions. Analysis of the CEMS spectra showed that both the "MgO/Fe" and "Fe/MgO" interfaces are partially oxidized (63% and 86%, respectively), although, despite good crystallinity, no well-defined iron oxide phases were detected. At the "MgO/Fe" interface, 14% of the oxidized Fe sites were found to be defective (located at steps, corners or kinks). The "Fe/MgO" interface, from which the formation of 57Fe islands of at least 3 ML in height was inferred, was found to be almost defect-free. No modification of the hyperfine parameters of Fe atoms located away from the interface was detected for "Fe/MgO," in contrast with the "MgO/Fe" interface. Approximately 6% of the probe layer diffused into the MgO films at both interfaces.

  11. Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF₂-MgO Carriers.

    PubMed

    Bonarowska, Magdalena; Wojciechowska, Maria; Zieliński, Maciej; Kiderys, Angelika; Zieliński, Michał; Winiarek, Piotr; Karpiński, Zbigniew

    2016-11-25

    Pd/MgO, Pd/MgF₂ and Pd/MgO-MgF₂ catalysts were investigated in the reaction of CCl₄ hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF₂-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C₂-C₅ hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF₂ is beneficial for shaping high activity of palladium catalysts. The MgO-MgF₂ support characterized by stronger Lewis acidity than MgF₂ contributes to very good catalytic activity for a relatively long reaction period (~5 h) but subsequent neutralization of stronger acid centers (by coking) eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO) are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

  12. Mg Incorporation Efficiency in Pulsed MOCVD of N-Polar GaN:Mg

    NASA Astrophysics Data System (ADS)

    Marini, Jonathan; Mahaboob, Isra; Hogan, Kasey; Novak, Steve; Bell, L. D.; Shahedipour-Sandvik, F.

    2017-10-01

    We report on the effect of growth polarity and pulsed or δ -doped growth mode on impurity incorporation in metalorganic chemical vapor deposition-grown GaN. In Ga-polar orientation, up to 12× enhancement in Mg concentration for given Mg flow rate is observed, resulting in enhanced p-type conductivity for these samples. In contrast, this enhancement effect is greatly diminished for N-polar samples, falling off with increasing Mg flow and showing maximum enhancement of 2.7× at 30 nmol/min Mg flow. At higher Mg flow rates, Mg incorporation at normal levels did not correspond to p-type conductivity, which may be due to Mg incorporation at nonacceptor sites. Concentrations of C, O, and Si were also investigated, revealing dependence on Mg flow in N-polar pulsed samples. Carbon incorporation was found to decrease with increasing Mg flow, and oxygen incorporation was found to remain high across varied Mg flow. These effects combine to result in N-polar samples that are not p-type when using the pulsed growth mode.

  13. Study on the compounds of Mg12La and (Mg,Zn)11.5La

    NASA Astrophysics Data System (ADS)

    Huang, M. L.; Si, Z. Y.; Li, H. X.

    2017-01-01

    The composition, crystal structure and phase relationship of the main intermetallics of the Mg-Zn-La system on the low La side have been studied. The results show that there exists a binary solid solutions of Mg12La as (Mg,Zn)La12 and a linear ternary compound (Mg,Zn)11.5La. Though the composition formula of the two phases are similar, but the composition of Zn in them are different. The maximum Zn content of (Mg,Zn)12La is 7.2at% and the minimum Zn content of (Mg,Zn)11.5La is 8.5at%. What’s more, the crystal structures of (Mg,Zn)12La and (Mg,Zn)11.5La phase are also totally different. (Mg,Zn)La12 have the body centered tetragonal lattice structure, but the crystal structure of (Mg,Zn)11.5La is C-centered orthorhombic lattice structure.

  14. Superior high-field current density in slightly Mg-deficient MgB2 tapes

    NASA Astrophysics Data System (ADS)

    Jiang, C. H.; Nakane, T.; Kumakura, H.

    2005-12-01

    A series of Fe-clad MgxB2 tapes with x varying from 0.5 to 1.2 was prepared by the in situ powder-in-tube method. Slightly Mg-deficient samples showed higher Jc in high magnetic fields, whereas samples with stoichiometric Mg or a slight excess of Mg exhibited better Jc in the low-field region. The sample with x =0.9 showed the best Jc in the applied magnetic field. The MgB2 core was porous in Mg-deficient tapes but with smaller grain sizes than the samples with a slight Mg excess due to insufficient grain growth. Some fine nanometer size grains were also observed in the B-rich samples. The enhanced grain boundary pinning due to the smaller grain size may explain the superior high-field Jc property of the slightly Mg-deficient MgB2 tapes. Our results indicate that preparing MgB2 samples with a slight excess of Mg may not be advantageous when developing devices for high-field applications.

  15. The effects of Mg enrichment of vegetable sprouts on Mg concentration, yield and ROS generation.

    PubMed

    Przybysz, Arkadiusz; Wrochna, Mariola; Małecka-Przybysz, Monika; Gawrońska, Helena; Gawroński, Stanisław W

    2016-08-01

    Two-thirds of the world's population do not consume the recommended amount of Mg, hence the demand for the production of Mg-enriched plants. Sprouts represent promising targets for enrichment. This study evaluated the effects of enriching broccoli, radish, alfalfa and mung bean sprouts with Mg (50-300 mg L(-1) ) on (i) the concentration of Mg and other ions, (ii) biomass accumulation, (iii) levels of reactive oxygen species (ROS), and (iv) the activity/content of enzymatic and non-enzymatic components of antioxidative systems. Enrichment of sprouts with Mg led to a significant increase in Mg concentration, especially in alfalfa (increase of 23-152 %), without depletion of other ions. A higher Mg concentration had a minor effect on biomass accumulation, but increased, often significantly, ROS generation and affected enzymatic and non-enzymatic antioxidative systems. The level of O2 (•-) increased most in broccoli, by 59-158%, while OH(•) increased most in radish, by 200-350%. Enrichment of sprouts with Mg is possible, but attention must be paid to elevated ROS levels in food. Mung bean sprouts are best suited to enrichment as they make a considerable contribution to the daily supplementation of Mg, at still low levels of ROS in enriched plants. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  16. A Range-Shift Technique for TOF Range Image Sensors

    NASA Astrophysics Data System (ADS)

    Sawada, Tomonari; Ito, Kana; Nakayama, Masakatsu; Kawahito, Shoji

    In Time-of-Flight (TOF) range image sensors using periodical pulsed light, there is a trade-off between the maximum range and range resolution. This paper proposes a range-shift technique for improving range resolution of the TOF range image sensor without sacrificing the measurement range. The range-shift operation uses a TOF range imaging pixel with periodical charge draining structure and several time-shifted short pulses. The use of the short pulse can improve the range resolution. The range image using the range-shift technique is synthesized with several sub-frames, each acquires one of the shifted range images. The use of the small duty-ratio pulse leads to reducing the effect of ambient light and improving the range resolution. The range-shift technique is tested with an implemented TOF range image sensor and it is found that the range resolution is improved to 2cm using a 10ns light pulse and 7 overlapped shifted ranges for the measurement range of 0.5m to 4.0m.

  17. Effect of secular variation in oceanic Mg/Ca on calcareous biomineralization

    NASA Astrophysics Data System (ADS)

    Ries, J. B.; Stanley, S. M.

    2006-12-01

    The polymorph mineralogy of simple, hypercalcifying marine organisms has generally varied in synchroneity with the polymorph mineralogy of abiotic CaCO3 precipitates (ooids, marine cements) throughout the Phanerozoic Eon. This synchroneity is caused by secular variation in the Mg/Ca ratio of seawater (SW; mMg/Ca > 2 = aragonite + high-Mg calcite; mMg/Ca < 2 = calcite), determined primarily by the mixing rate of mid-ocean-ridge/large-igneous-province hydrothermal brines and river water, driven by the global rate of ocean crust production. Here, we present experiments evaluating the effect of seawater Mg/Ca on the biomineralization and growth of extant representatives of hypercalcifying taxa that have been subjected to fluctuations in oceanic Mg/Ca in the past. Codiacean algae (arag), scleractinian corals (arag), coccolithophores (low-high Mg-calc), coralline algae (high Mg-calc), various reef-dwelling animals (echinoids, crabs, shrimp, calcareous serpulid worms; high Mg- calc), and calcifying microbial mats (arag + high-Mg calc) were grown in artificial SW formulated over the range of mMg/Ca (1.0 to 5.2) that occurred throughout each taxon's history. Codiacean algae and scleractinian corals exhibited higher rates of calcification and growth in artificial SW favoring their aragonite mineralogy and, significantly, produced a portion of their CaCO3 as calcite in the artificial calcite SW. Coccolithophores (low-high Mg calc.) showed higher calcification and growth rates and produced low-Mg calcite in the calcite SW. Likewise, coralline algae and the reef-dwelling animals (high-Mg calc) varied skeletal Mg/Ca with seawater Mg/Ca. The calcifying microbial mats grew equally well in the calcite and aragonite SW and varied their mineral polymorph commensurate with the SW (mMg/Ca<2 = low- Mg calc; mMg/Ca>2 = arag + high-Mg calc), suggesting a nearly abiotic mode of calcification. The precipitation of low-Mg calcite + aragonite by codiacean algae and scleractinian corals (arag

  18. The Lunar Highland Crust: The Origin of the MG Suite

    NASA Astrophysics Data System (ADS)

    Taylor, S. R.; Norman, M. D.; Esat, T.

    1993-07-01

    Norites, troctolites, dunites, spinel troctolites and gabbronorites form the Mg suite, which constitutes perhaps 20% of the highland crust. Their ages range from about 4.43 b.y. down to about 4.17 b.y. The Mg suite does not appear to be related to crystallization from the magma ocean. These rock types commonly have Mg# > 90 and so are "primitive," but also contain high concentrations of incompatible elements, typical of highly "evolved" igneous rocks. An origin by mixing of these two distinct components, one "primitive" to account for the major elements (particularly the high Mg#), and the other "evolved" to account for the high trace-element abundances, is suggested by these contradictory petrochemical characteristics. The source of the highly evolved trace-element component is clearly KREEP. The source of the "primitive" Mg-rich component is less clear. Many theories propose that the Mg-suite rocks are derived from different plutons that intruded the crust as separate igneous intrusions. However, all Mg-suite rocks have REE patterns parallel to those of KREEP and the ferroan anorthosites. This characteristic is compatible with mixing, but should not be expected to be duplicated in many separate igneous intrusions. The Mg suite also contains Mg-rich orthopyroxene, a mineral lacking in most mare basalts, so that the source regions of the mare basalts were distinct from those of the Mg suite. During crystallization of the lunar magma ocean, Mg-rich minerals accumulate on the bottom of the magma chamber at depths probably exceeding 400 km. It has been suggested that massive overturning of the crystal pile has occurred to bring these Mg-rich minerals close to the surface. The source regions of the mare basalts were solid by 4400 m.y. with only the minor KREEP component remaining liquid until about 4360 m.y. Thus the lunar interior was effectively solid, although still hot, at the time of the formation of the Mg suite. It thus seems difficult to envisage a massive

  19. Crystal structure of MgO along the shock Hugoniot

    NASA Astrophysics Data System (ADS)

    Smith, R.; Wicks, J. K.; Kraus, R. G.; Eggert, J.; Coppari, F.; Newman, M.; Millot, M. A.; Duffy, T. S.

    2016-12-01

    As many as 30% of main sequence stars are estimated to have planetary companions. Of the more than 6000 confirmed and candidate extrasolar planets discovered to date those that are 1-4 times the radius of the Earth are now known to be the most abundant. Determining the interior structure and composition of exoplanets is challenging but is key to understanding the diversity and evolution of planetary systems. The silicate compounds that dominate the Earth's mantle likely dissociate into component oxides at the extreme pressures (200-2000 GPa) and temperatures (5000-10000 K) existing in super-Earth mantles. Magnesium oxide (periclase), an end-member of the ferropericlase solid solution (Mg,Fe)O and an important component the Earth's mantle, has been thoroughly studied under static compression in the pressure and temperature range found within the Earth ( 135 GPa, 2500-4000K). However, as static compression techniques are typically limited to peak pressures of < 200 GPa, much less is known about its behavior under high-pressure and -temperature conditions. In our experiments, the structure of MgO upon shock compression over the 200-700 GPa pressure range was interrogated at the Omega-EP Laser facility at the Laboratory for Laser Energetics, University of Rochester. Laser drives of up to 2 kJ over 10 ns focused onto a polyimide ablator were used to shock compress 50-um thick polycrystalline or single-crystal MgO. Scattered He-α X-rays from an Cu backlighter timed with maximum compression were collected using the PXRDiP diagnostic, in which image plates line the inner walls of a box attached to the target package. Along the shock Hugoniot MgO transforms from a B1-B2 phase transformation at 400 GPa and B2-liquid at 700 GPa. For each pressure we measure pressure (velocity interferometry), density (x-ray diffraction) and shock temperature (pyrometry).

  20. Dielectric relaxation behavior of acceptor (Mg)-doped BaTiO3

    NASA Astrophysics Data System (ADS)

    Yoon, Seok-Hyun; Kwon, Sang-Hoon; Hur, Kang-Heon

    2011-04-01

    Dielectric relaxation behavior of acceptor (Mg)-doped BaTiO3 ceramics was investigated with the increase of Mg concentration up to 0.6 mol. % in the temperature rang of 120 ˜ 540 °C. In the high temperature range above 320 °C, the activation energies of dielectric relaxation (Eτ) showed nearly similar values of ˜ 1.2 eV irrespective of Mg concentration. However, in the low temperature range below 320 °C, they continuously decreased from ˜ 1.2 eV and then saturated to ˜ 0.4 eV with the increase of Mg concentration. The activation energies of electrical conduction (Eσ) of the bulk grain evaluated by impedance analysis also showed almost the same behavior. Such coincidence demonstrates that the observed dielectric behaviors are caused by the space charge polarization at grain boundaries by conducting charge carriers. The disappearance of the dielectric relaxation in submicrometer fine-grain specimen also supports this mechanism. The variation of Eτ and Eσ with the increase of Mg concentration in the low temperature range was supposed to be caused by the dominant hopping conduction between ionized acceptor (MgTi″) and neutral or hole-trapped acceptor (MgTi×).

  1. Superconductivity in MgB 2

    NASA Astrophysics Data System (ADS)

    Akimitsu, Jun; Muranaka, Takahiro

    2003-05-01

    We recently discovered that the intermetallic compound magnesium diboride (MgB2) exhibits the highest superconducting transition temperature (Tc=39 K) of all the metallic superconductors. In this paper we report on the basic superconducting characteristics of MgB2 and the current status of the research for the unanswered problem in this superconductivity. Especially, we review the several reports for the superconducting gap (Δ) by the spectroscopic measurements. Moreover we introduce the research into its anisotropic parameter (γ), which is important for the understanding of this superconducting states in this material.

  2. Electronic states of MgO: Spectroscopy, predissociation, and cold atomic Mg and O production

    SciTech Connect

    Maatouk, A.; Ben Houria, A.; Yazidi, O.; Jaidane, N.; Hochlaf, M.

    2010-10-14

    We used multiconfigurational methods and a large basis set to compute the potential energy curves of the valence and valence-Rydberg electronic states of MgO molecule. New bound electronic states are found. Using these highly correlated wave functions, we evaluated their mutual spin-orbit couplings and transition moment integrals. For the bound electronic states of MgO, we deduced an accurate set of spectroscopic constants that agree remarkably well with experimental results. Moreover, our potentials, transition moments, and spin-orbit coupling evolutions are incorporated into Fermi golden rule calculations to deduce the radiative lifetimes of MgO(B {sup 1}{Sigma}{sup +}) rovibrational levels and the natural lifetimes of MgO(A {sup 1}{Pi}) vibrational levels, where a good agreement is found with experimental values. Finally, we suggest new routes for the production of cold Mg and O atoms and cold MgO molecules.

  3. The millimeter-wave spectrum of the MgH and MgD radicals

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Barclay, W. L., Jr.; Anderson, M. A.

    1993-01-01

    The pure rotational spectrum of MgH radical (X 2 Sigma (+)) in its ground state v = 0 and v = 1 vibrational modes has been observed in the laboratory using millimeter/submillimeter direct absorption spectroscopy. The rotational spectra of two isotopically substituted species, MgD and (Mg-26)H, have been detected as well. All six hyperfine components of the N = 0 -1 transition of MgH in its v = 0 and v = 1 states have been directly measured to an accuracy of +/-50 kHz, and the five components have been observed for (Mg-26)H. The N = 0 +/-1 and N = 1 -2 transitions of MgD have also been detected. Rotational, fine structure, and hyperfine constants were determined for all species from a nonlinear least-squared fit to the data using a 2 Sigma Hamiltonian.

  4. Interdiffusion in the Mg-Al system and Intrinsic Diffusion in (Al3Mg2) Phase

    SciTech Connect

    Brennan, Sarah; Bermudez, Katrina; Kulkarni, Nagraj S; Sohn, Yong Ho

    2011-01-01

    Increasing use and development of lightweight Mg-alloys have led to the desire for more fundamental research in and understanding of Mg-based systems. As a strengthening component, Al is one of the most important and common alloying elements for Mg-alloys. In this study, solid-to-solid diffusion couple techniques were employed to examine the interdiffusion between pure Mg and Al. Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopies (SEM) were employed to observe the formation of the intermetallics -Al12Mg17 and -Al3Mg2, but not -phase. Concentration profiles were determined using X-ray energy dispersive spectroscopy (XEDS). The growth constants and activation energies were determined for each intermetallic phase.

  5. Electron microscopy observations of MgB 2 wire prepared by an internal Mg diffusion method

    NASA Astrophysics Data System (ADS)

    Shimada, Y.; Kubota, Y.; Hata, S.; Ikeda, K.; Nakashima, H.; Matsumoto, A.; Togano, K.; Kumakura, H.

    2011-11-01

    Microstructure in a high-density MgB2 wire fabricated by an internal Mg diffusion (IMD) process has been investigated by electron microscopy imaging and analysis at different scales. In the IMD process, a pure Mg rod was used as Mg source, and nanosized SiC powders were mixed with amorphous B powders. In the case of a heat treatment at 640 °C for 1 h carried out after rolling and drawing processes, the wire has two microstructural features that degrade critical current density: uncrystallized zones composed mainly of unreacted B and SiC powders, and cracks partly filled with course Mg2Si crystals. Those cracks were formed in the uncrystallized zones as well as in crystallized MgB2 zones. It indicate that the cracks formed by the mechanical milling and drawing remain after the heat treatment.

  6. Efficient hydrogen storage with the combination of lightweight Mg/MgH2 and nanostructures.

    PubMed

    Cheng, Fangyi; Tao, Zhanliang; Liang, Jing; Chen, Jun

    2012-07-28

    Efficient hydrogen storage plays a key role in realizing the incoming hydrogen economy. However, it still remains a great challenge to develop hydrogen storage media with high capacity, favourable thermodynamics, fast kinetics, controllable reversibility, long cycle life, low cost and high safety. To achieve this goal, the combination of lightweight materials and nanostructures should offer great opportunities. In this article, we review recent advances in the field of chemical hydrogen storage that couples lightweight materials and nanostructures, focusing on Mg/MgH(2)-based systems. Selective theoretical and experimental studies on Mg/MgH(2) nanostructures are overviewed, with the emphasis on illustrating the influences of nanostructures on the hydrogenation/dehydrogenation mechanisms and hydrogen storage properties such as capacity, thermodynamics and kinetics. In particular, theoretical studies have shown that the thermodynamics of Mg/MgH(2) clusters below 2 nm change more prominently as particle size decreases.

  7. The millimeter-wave spectrum of the MgH and MgD radicals

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Barclay, W. L., Jr.; Anderson, M. A.

    1993-01-01

    The pure rotational spectrum of MgH radical (X 2 Sigma (+)) in its ground state v = 0 and v = 1 vibrational modes has been observed in the laboratory using millimeter/submillimeter direct absorption spectroscopy. The rotational spectra of two isotopically substituted species, MgD and (Mg-26)H, have been detected as well. All six hyperfine components of the N = 0 -1 transition of MgH in its v = 0 and v = 1 states have been directly measured to an accuracy of +/-50 kHz, and the five components have been observed for (Mg-26)H. The N = 0 +/-1 and N = 1 -2 transitions of MgD have also been detected. Rotational, fine structure, and hyperfine constants were determined for all species from a nonlinear least-squared fit to the data using a 2 Sigma Hamiltonian.

  8. Superconductivity in MgPtSi: An orthorhombic variant of MgB2

    NASA Astrophysics Data System (ADS)

    Kudo, Kazutaka; Fujimura, Kazunori; Onari, Seiichiro; Ota, Hiromi; Nohara, Minoru

    2015-05-01

    A ternary compound, MgPtSi, was synthesized by solid-state reaction. An examination of the compound by powder x-ray diffraction revealed that it crystallizes in the orthorhombic TiNiSi-type structure with the P n m a space group. The structure comprises alternately stacked layers of Mg and PtSi honeycomb network, which is reminiscent of MgB2, and the buckling of the honeycomb network causes orthorhombic distortion. Electrical and magnetic studies revealed that MgPtSi exhibited superconductivity with a transition temperature of 2.5 K. However, its isostructural compounds, namely, MgRhSi and MgIrSi, were not found to exhibit superconductivity.

  9. Spontaneous polarization driven Mg concentration profile reconstruction in MgZnO/ZnO heterostructures

    SciTech Connect

    Imasaka, K.; Falson, J.; Kozuka, Y. Kawasaki, M.; Tsukazaki, A.

    2014-06-16

    Atomic reconstruction at the interface of MgZnO and ZnO in molecular beam epitaxy grown heterostructures is investigated. Using secondary ion mass spectroscopy, we experimentally find that Mg atomic reconstruction depends on the polarity of the interface; it is not observed in n-type interfaces (MgZnO on Zn-polar ZnO) owing to electron accumulation, while in p-type interfaces (ZnO on Zn-polar MgZnO), Mg drastically redistributes into the ZnO layer. Combined with self-consistent calculation of band profiles and carrier distributions, we reveal that the observed Mg reconstruction is not due to thermal diffusion but consequences in order to avoid hole accumulation. This tendency implies inherent significant asymmetry of energy scales of atomic and electronic reconstructions between n-type and p-type interfaces.

  10. Mg2(Si,Sn)-based thermoelectric materials and devices

    NASA Astrophysics Data System (ADS)

    Gao, Peng

    Thermoelectric effects are phenomena found in materials that can achieve direct conversion between heat flow and electricity. One important application of thermoelectric effects is thermoelectric generators, which can generate electricity when a temperature gradient is applied. Thermoelectric generators make use of various sources of heat and it is considered a promising solution for waste heat recovery. The conversion efficiency of thermoelectric generators depends on the materials used in the devices. Significant improvement in the performance of thermoelectric materials has been made in the past few decades. However, most of the good thermoelectric materials being investigated have limitations, such as the high materials cost, high materials density and toxicity of the constituent elements. The Mg2(Si,Sn)-based materials studied in this work are promising candidates for thermoelectric generators in the mid-temperature range and have drawn increasing research interest in recent years because these materials are high performance thermoelectrics that are low cost, low-density and non-toxic. In this work, systematic studies were performed on the Mg2(Si,Sn) thermoelectric materials. Thermal phase stability was studied for different compositions of Mg2Si1-xSnx and Mg2Si0.4Sn 0.6 was used as base material for further optimization. Both n-type and p-type samples were obtained by doping the materials with different elements. Peak ZT ˜ 1.5 for the n-type and ZT ˜ 0.7 for the p-type materials were obtained, both of which are among the best reported results so far. Experimental work was also done to study the techniques to develop the Mg2Si 0.4Sn0.6 materials into working devices. Different electrode materials were tested in bonding experiment for this compound, and copper was found to be the best electrode material for Mg2Si 0.4Sn0.6. Preliminary work was done to demonstrate the possibility of fabricating a Mg2Si0.4Sn0.6-based thermoelectric generator and the result is

  11. Temperature-dependent VNIR spectroscopy of hydrated Mg-sulfates

    NASA Astrophysics Data System (ADS)

    De Angelis, S.; Carli, C.; Tosi, F.; Beck, P.; Schmitt, B.; Piccioni, G.; De Sanctis, M. C.; Capaccioni, F.; Di Iorio, T.; Philippe, Sylvain

    2017-01-01

    We investigate two poly-hydrated magnesium sulfates, hexahydrite (MgSO4 · 6H2O) and epsomite (MgSO4 · 7H2O), in the visible and infrared (VNIR) spectral range 0.5/4.0 μm, as particulate for three different grain size ranges: 20-50 μm, 75-100 μm and 125-150 μm. All samples were measured in the 93-298 K temperature range. The spectra of these hydrated salts are characterized by strong OH absorption bands in the 1.0-1.5 μm region, and by H2O absorption bands near 2 and 3 μm. Other weak features show up at low temperatures near 1.75 μm (in both hexahydrite and epsomite) and 2.2 μm (only in hexahydrite). The spectral behavior of the absorption bands of these two minerals has been analyzed as a function of both grain size and temperature, deriving trends related to specific spectral parameters such as band center, band depth, band area, and band width. Hydrated minerals, in particular mono- and poly-hydrated sulfates, are present in planetary objects such as Mars and the icy Galilean satellites. Safe detection of these minerals shall rely on detailed laboratory investigation of these materials in different environmental conditions. Hence an accurate spectral analysis of such minerals as a function of temperature is key to better understand and constrain future observations.

  12. Chemical Interaction of Mg-CARBONATE and the Earth's Lower Mantle Minerals

    NASA Astrophysics Data System (ADS)

    Spivak, Anna; Solopova, Natalia; Litvin, Yuriy; Dubrovinsky, Leonid

    2013-04-01

    Diamonds of lower mantle origin are rare but important guests at Earth surface currying crucial information about deep interiors. Apart minerals expected to be similar in Earth lower mantle (particularly Mg-Fe-Al silicates and MgO-FeO oxides) ultra-deep diamonds contain primary inclusions of carbonates indicating that they are presented in the Earth lower mantle. Carbonates of magnesium, calcium, iron and sodium are stable at wide pressure-temperature conditions close to the geotherm. We studied interaction of Mg-carbonates with ferropericlase, perovskite employing laser-heated diamond anvil cell (DAC) at pressures up to 60 GPa and temperatures over 3000 K. Melting of Mg-carbonate is determined as congruent under PT-conditions of the lower mantle. The MgCO3 melts are stable in an expanded high-pressure high-temperature field. We observed formation of diamond at 18 and 40 GPa as a result of decomposition of MgCO3 melt at temperatures above 3500 K on the high-temperature boundary of the field. Melting reactions of the MgCO3-(Mg,Fe)O system were studied in the 30-63 GPa range at high temperatures up to 3600 K. It was found that decomposition boundary of MgCO3-(Mg,Fe)O melt is close to the pure MgCO3 decomposition one within ± 150 K (accuracy of DAC experiment). Preliminary data shows that perovskite -(Mg,Fe)(Si,Al)O3reacts with MgCO3 at PT-conditions of 24GPa/2000K and 60GPa/2500K, that is close to the boundary of congruent MgCO3 melting. The reaction is accompanied with formation of diamond and MgO. The experimental data on melting phase relations MgCO3, MgCO3 - (Mg,Fe)O and MgCO3-(Mg,Fe)(Si,Al)O3 systems combined with diamond crystallization are applied to the problem of ultra-deep diamond formation in carbonate-bearing parental media of the Earth's lower mantle. This work was funded by the Ministry of education and science of Russian Federation, project 8317, 16.740.11.0621, grants RFBR 12-05-33044 and 11-05-000401.

  13. Rechargeable Mg batteries with graphene-like MoS₂ cathode and ultrasmall Mg nanoparticle anode.

    PubMed

    Liang, Yanliang; Feng, Rujun; Yang, Siqi; Ma, Hua; Liang, Jing; Chen, Jun

    2011-02-01

    The combination of a highly exfoliated, graphene-like MoS₂ cathode and ultrasmall Mg nanoparticle anode is proposed, for the first time, for rechargeable Mg batteries. Such a configuration exhibits an operating voltage of 1.8 V and a well reversible discharge capacity of ca. 170 mA h g−1, emphasizing the necessity of rational morphological control of electrode materials and opening up new opportunities for rechargeable Mg batteries.

  14. Influence of RCS on Al-3Mg and Al-3Mg-0.25Sc alloys

    NASA Astrophysics Data System (ADS)

    Bhovi, Prabhakar M.; Venkateswarlu, K.

    2016-02-01

    An influence of repetitive corrugation and straightening (RCS) was studied on Al-3Mg and Al-3Mg-0.25Sc alloys up to eight passes. Each pass consist of a corrugation and followed by straightening. This has resulted in introducing large plastic strain in sample, and thus led to formation of sub-micron grain sizes with high angle grain boundaries. These sub grain formation was eventually resulted in improved mechanical properties. The average grain size of Al-3Mg-0.25Sc alloy after 8 passes yielded to ∼0.6pm. Microhardness, strength properties were evaluated and it suggests that RCS was responsible for high hardness values as compared to the as cast samples. The microhardness values after RCS were 105 HV and 130 HV for Al-3Mg and Al-3Mg-0.25Sc alloys, respectively. Similarly, ∼ 40% improvement in tensile strength from 240 MPa to 370 MPa was observed for Al- 3Mg-0.25Sc alloy after RCS process.Al-3Mg and Al-3Mg-0.25Scalloys exhibited maximum strength of 220 MPa and 370 MPa, respectively. It is concluded that RCS process has a strong influence on Al- 3Mg and Al-3Mg-0.25Sc alloys for obtaining improved mechanical properties and grain refinement. In addition to RCS process and presence of AESc precipitates in Al-3Mg-0.25Sc alloy had a significant role in grain refinement and improved mechanical properties as compared to Al-3Mg alloy.

  15. Temperature dependence of resistance in epitaxial Fe/MgO/Fe magnetic tunnel junctions

    SciTech Connect

    Ma, Q. L.; Wang, Shouguo; Wang, Y.; Zhang, J.; Ward, R. C. C.; Kohn, A.; Zhang, Xiaoguang; Han, Prof. X. F.

    2009-01-01

    The temperature dependence of resistance in parallel P and antiparallel AP configurations RP,AP has been investigated in epitaxial Fe/MgO/Fe junctions with varying MgO barrier thicknesses tMgO. RAP exhibits a substantial decrease with increasing temperature for samples with tMgO ranging from 3.0 to 1.5 nm. In contrast, RP is approximately temperature independent when tMgO =3.0 nm and increases with temperature when tMgO=2.1 and 1.5 nm. Possible origins of this temperature dependence of resistance, which include taking into account a spin independent term and consideration of spin-flip scattering, are discussed. We attribute the temperature dependence of RP,AP to the misalignment of magnetic moments in the electrodes due to thermal excitations and its effect on the spin dependent tunneling.

  16. Ultrathin MgO diffusion barriers for ferromagnetic electrodes on GaAs(001).

    PubMed

    Sarkar, Anirban; Wang, Shibo; Grafeneder, Wolfgang; Arndt, Martin; Koch, Reinhold

    2015-04-24

    Ultrathin MgO(100) films serving as a diffusion barrier between ferromagnetic electrodes and GaAs(001) semiconductor templates have been investigated. Using Fe as an exemplary ferromagnetic material, heterostructures of Fe/MgO/GaAs(001) were prepared at 200 °C with the MgO thickness ranging from 1.5 to 3 nm. Structural characterization reveals very good crystalline ordering in all layers of the heterostructure. Auger electron spectroscopy depth-profiling and cross-sectional high-resolution transmission electron microscopy evidence diffusion of Fe into MgO and-for too thin MgO barriers-further into GaAs(001). Our results recommend a MgO barrier thickness larger than or equal to 2.6 nm for its application as a reliable diffusion barrier on GaAs(001) in spintronics devices.

  17. Synthesis of MgO powder from magnesium nitrate using spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Pradita, T.; Shih, S. J.; Aji, B. B.; Sudibyo

    2017-03-01

    A variety of advantages such as catalyst, paints, flame retardants, semiconductors, additives in refractory and solid adsorbent can be obtained from Magnesium Oxide (MgO) based material. Ultrasonic spray pyrolysis (SP) process was conducted to synthesize MgO from Mg(NO3)2.6H2O (MgN) precursor. The MgO particles were characterized using Thermogravimetric Analysis (TGA), X-Ray Diffraction analysis (XRD) and Field Emission-Secondary Electron Microscopy (FE-SEM). In this study, Hollow spherical and irregular MgO particles were successfully obtained. It suggests that the particle size will decrease along with the increasing of the SP temperature, the smallest particle size obtained is in the range of 354±104 nm at 900°C SP temperature.

  18. Effect of MgO and Basicity on Microstructure and Metallurgical Properties of Iron Ore Sinter

    NASA Astrophysics Data System (ADS)

    Zhang, Mingming; Andrade, Marcelo W.

    The metallurgical properties of iron ore sinter mainly depends on sinter mineralogy and microstructure, which in turn depends on the chemical composition of the sinter mix. In order to meet blast furnace requirement on sinter quality, it is essential to optimize the MgO in sinter mix and sinter basicity to get desired properties. Laboratory pot grate sintering experiments and quantitative analysis of sinter mineralogical phases have been carried out to investigate the influence of MgO addition on microstructure and properties of low basicity and high basicity sinter. MgO addition has been varied from 2. 2 to 4. 5% for low basicity (2. 1), and high basicity (3. 5) sinter mixes. Mineralogical examination indicated that Magnetite-Mg phases increases when MgO content in sinter increases. To achieve balanced sinter quality to meet blast furnace specifications, high basicity with medium range of MgO sinter was recommended to sinter plant.

  19. The Interplay of Al and Mg Speciation in Advanced Mg Battery Electrolyte Solutions.

    PubMed

    See, Kimberly A; Chapman, Karena W; Zhu, Lingyang; Wiaderek, Kamila M; Borkiewicz, Olaf J; Barile, Christopher J; Chupas, Peter J; Gewirth, Andrew A

    2016-01-13

    Mg batteries are an attractive alternative to Li-based energy storage due to the possibility of higher volumetric capacities with the added advantage of using sustainable materials. A promising emerging electrolyte for Mg batteries is the magnesium aluminum chloride complex (MACC) which shows high Mg electrodeposition and stripping efficiencies and relatively high anodic stabilities. As prepared, MACC is inactive with respect to Mg deposition; however, efficient Mg electrodeposition can be achieved following an electrolytic conditioning process. Through the use of Raman spectroscopy, surface enhanced Raman spectroscopy, (27)Al and (35)Cl nuclear magnetic resonance spectroscopy, and pair distribution function analysis, we explore the active vs inactive complexes in the MACC electrolyte and demonstrate the codependence of Al and Mg speciation. These techniques report on significant changes occurring in the bulk speciation of the conditioned electrolyte relative to the as-prepared solution. Analysis shows that the active Mg complex in conditioned MACC is very likely the [Mg2(μ-Cl)3·6THF](+) complex that is observed in the solid state structure. Additionally, conditioning creates free Cl(-) in the electrolyte solution, and we suggest the free Cl(-) adsorbs at the electrode surface to enhance Mg electrodeposition.

  20. The Interplay of Al and Mg Speciation in Advanced Mg Battery Electrolyte Solutions

    SciTech Connect

    See, Kimberly A.; Chapman, Karena W.; Zhu, Lingyang; Wiaderek, Kamila M.; Borkiewicz, Olaf J.; Barile, Christopher J.; Chupas, Peter J.; Gewirth, Andrew A.

    2016-01-13

    Mg batteries are an attractive alternative to Li-based energy storage due to the possibility of higher volumetric capacities with the added advantage of using sustainable materials. A promising emerging electrolyte for Mg batteries is the magnesium aluminum chloride complex (MACC) which shows high Mg electrodeposition and stripping efficiencies and relatively high anodic stabilities. As prepared, MACC is inactive with respect to Mg deposition; however, efficient Mg electrodeposition can be achieved following an electrolytic conditioning process. Through the use of Raman spectroscopy, surface enhanced Raman spectroscopy, 27Al and 35Cl nuclear magnetic resonance spectroscopy, and pair distribution function analysis, we explore the active vs inactive complexes in the MACC electrolyte and demonstrate the codependence of Al and Mg speciation. These techniques report on significant changes occurring in the bulk speciation of the conditioned electrolyte relative to the as-prepared solution. Analysis shows that the active Mg complex in conditioned MACC is very likely the [Mg2(μ–Cl)3·6THF]+ complex that is observed in the solid state structure. Additionally, conditioning creates free Cl– in the electrolyte solution, and we suggest the free Cl– adsorbs at the electrode surface to enhance Mg electrodeposition.

  1. Comparing Doping Methodologies in Mg2Si/AgMg System

    NASA Astrophysics Data System (ADS)

    Polymeris, G. S.; Theodorakakos, A.; Mars, K.; Godlewska, E.; Lioutas, Ch. B.; Hatzikraniotis, E.; Paraskevopoulos, K. M.

    2014-10-01

    Morphological and optical characterizations for the Mg2Si samples doped with Ag are presented. Two different doping methodologies with silver, namely in situ and ex situ doping, were studied for the case of Mg2Si of self-propagating high-temperature synthesis. Electron microscopy measurements in both scanning and transmission configurations verified the presence of AgMg precipitates embedded in the Mg2Si matrix and similar results were also yielded by FTIR spectroscopy. Finally, the dependence of silver content in both forms of dopant and inter-metallic constituent is studied upon doping technology.

  2. Microstructure and hydrogen storage properties of Mg-Ni-Ce alloys with a long-period stacking ordered phase

    NASA Astrophysics Data System (ADS)

    Xie, Lishuai; Li, Jinshan; Zhang, Tiebang; Song, Lin; Kou, Hongchao

    2017-01-01

    On the basis of catalytic actions of transition metals and rare earth metals on Mg-based hydrogen storage alloys and aiming at alleviating the adverse influence of Mg oxidation, Mg-Ni-Ce alloys with different Ni and Ce contents were prepared by near equilibrium solidification. A new 18R-type long-period stacking ordered phase (LPSO) was formed coherently with Mg, Ni-substituted Mg12Ce and Mg2Ni in Mg-rich Mg-Ni-Ce ternary alloys. Distinct from the reported LPSO structures in other Mg-based alloys, in which the LPSO structures were fundamentally long period stacking variants of hexagonal close-packed structure of Mg, the LPSO structure found in the present work was a variant of Mg12Ce. Nanocrystalline alloys were obtained by high-energy ball milling the as-cast alloys. Nanocrystals of Mg, Mg2Ni and Mg12Ce with grain size in the range of 3-5 nm were observed in ball milled samples. The activation performance, isothermal hydrogenation behavior and anti-oxidation properties of the ball milled samples were systematically investigated and corresponding mechanisms were discussed based on detailed microstructural characteristics. CeH2.73 was formed after hydrogenation and spontaneously transformed into CeO2 during air exposure. The anti-oxidation properties of Mg-based hydrogen storage alloy were substantially improved with the addition of Ce by forming CeH2.73/CeO2 composite.

  3. Recovery of SO2 and MgO from By-Products of MgO Wet Flue Gas Desulfurization.

    PubMed

    Yan, Liyun; Lu, Xiaofeng; Wang, Quanhai; Guo, Qiang

    2014-11-01

    An industrial demonstration unit using natural gas as a heat source was built to calcine the by-products of MgO wet flue gas desulfurization from power plants; influencing factors on the SO2 content in calciner gas were comprehensively analyzed; and an advantageous recycling condition of MgO and SO2 from by-products was summarized. Results showed that the SO2 content in the calciner gas was increased by more than 10 times under a lower excess air coefficient, a higher feed rate, a lower crystal water in by-products, and a higher feed port position. For the tests conducted under the excess air coefficient above and below one, the effect of the furnace temperature on the SO2 content in the calciner gas was reversed. Results of activity analysis indicate that particles of MgO generated under the calcination temperature of 900-1,000°C had a high activity. In contrast, due to the slight sintering, MgO generated under the calcination temperature of 1,100°C had a low activity. To recycle SO2 as well as MgO, a temperature range of 900-927°C for TE103 is proposed. These studies will prompt the desulfurization market diversification, reduce the sulfur's dependence on imports for making sulfuric acid, be meaningful to balance the usage of the natural resource in China, and be regarded as a reference for the development of this technology for other similar developing countries.

  4. Recovery of SO2 and MgO from By-Products of MgO Wet Flue Gas Desulfurization

    PubMed Central

    Yan, Liyun; Lu, Xiaofeng; Wang, Quanhai; Guo, Qiang

    2014-01-01

    Abstract An industrial demonstration unit using natural gas as a heat source was built to calcine the by-products of MgO wet flue gas desulfurization from power plants; influencing factors on the SO2 content in calciner gas were comprehensively analyzed; and an advantageous recycling condition of MgO and SO2 from by-products was summarized. Results showed that the SO2 content in the calciner gas was increased by more than 10 times under a lower excess air coefficient, a higher feed rate, a lower crystal water in by-products, and a higher feed port position. For the tests conducted under the excess air coefficient above and below one, the effect of the furnace temperature on the SO2 content in the calciner gas was reversed. Results of activity analysis indicate that particles of MgO generated under the calcination temperature of 900–1,000°C had a high activity. In contrast, due to the slight sintering, MgO generated under the calcination temperature of 1,100°C had a low activity. To recycle SO2 as well as MgO, a temperature range of 900–927°C for TE103 is proposed. These studies will prompt the desulfurization market diversification, reduce the sulfur's dependence on imports for making sulfuric acid, be meaningful to balance the usage of the natural resource in China, and be regarded as a reference for the development of this technology for other similar developing countries. PMID:25371652

  5. Spin and magnetic moment of 23Mg

    NASA Astrophysics Data System (ADS)

    Yordanov, D. T.; Bissell, M. L.; Blaum, K.; De Rydt, M.; Geppert, Ch; Krämer, J.; Kreim, K.; Kowalska, M.; Krieger, A.; Lievens, P.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Rodríguez, L. V.; Sánchez, R.; Vingerhoets, P.

    2017-07-01

    A negative magnetic moment of 23Mg has been determined by collinear laser spectroscopy at CERN-ISOLDE. The absolute value is in agreement with previous measurements by nuclear magnetic resonance while the sign points at high-seniority configurations. The result is consistent with shell-model predictions for nuclei with valence nucleons in the sd shell.

  6. Controls of carbonate mineralogy and solid-solution of Mg in calcite: evidence from spelean systems

    SciTech Connect

    Gonzalez, L.A.; Lohmann, K.C.

    1985-01-01

    Precipitation of carbonate minerals in spelean systems occurs under a wide range of fluid chemistry, Mg-Ca ratios, alkalinities, pH and temperatures; thus, spelean systems provide ideal settings to determine factors controlling the mineralogy of precipitated carbonates and solid-solution of Mg in calcite. Cave waters and actively-precipitating carbonate speleothems were collected from Carlsbad Caverns National Park, New Mexico and the Mammoth-Flint Cave System, Kentucky. Carbonate mineralogy of precipitated phases was determined by x-ray diffraction, and major and minor element composition of waters and accompanying minerals were determined by Atomic Absorption Spectrophotometry. Results demonstrate that at a constant CO3 concentration the precipitation threshold for calcite to aragonite is controlled dominantly by the Mg/Ca ratio of the ambient fluid. Aragonite precipitation is favored by high Mg/Ca ratios. Conversely, with increasing CO3 concentration at constant fluid Mg/Ca ratios, calcite is preferentially precipitated. Solid-solution of Mg in calcite is positively correlated with both increased Mg/Ca ratios and CO3 concentrations. These data suggest that Mg contents of calcite can not be defined solely in terms of a homogeneous distribution coefficient. Rather, Mg concentrations can be also be affected by the CO3 concentration and degree of calcite saturation, suggesting that the rate of crystal growth also plays and important role in Mg solid-solution in calcites.

  7. Biocompatibility Assessment of Novel Bioresorbable Alloys Mg-Zn-Se and Mg-Zn-Cu for Endovascular Applications: In- Vitro Studies

    PubMed Central

    Budiansky, Noah; McGoron, Anthony J.

    2013-01-01

    Previous studies have shown that using biodegradable magnesium alloys such as Mg-Zn and Mg-Zn-Al possess the appropriate mechanical properties and biocompatibility to serve in a multitude of biological applications ranging from endovascular to orthopedic and fixation devices. The objective of this study was to evaluate the biocompatibility of novel as-cast magnesium alloys Mg-1Zn-1Cu wt.% and Mg-1Zn-1Se wt.% as potential implantable biomedical materials, and compare their biologically effective properties to a binary Mg-Zn alloy. The cytotoxicity of these experimental alloys was evaluated using a tetrazolium based- MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and a lactate dehydrogenase membrane integrity assay (LDH). The MTS assay was performed on extract solutions obtained from a 30-day period of alloy immersion and agitation in simulated body fluid to evaluate the major degradation products eluted from the alloy materials. Human foreskin fibroblast cell growth on the experimental magnesium alloys was evaluated for a 72 hour period, and cell death was quantified by measuring lactate dehydrogenase concentrations. Both Mg-Zn-Se and Mg-Zn-Cu alloys exhibit low cytotoxicity levels which are suitable for biomaterial applications. The Mg-Zn-Cu alloy was found to completely degrade within 72 hours, resulting in lower human foreskin fibroblast cell viability. The Mg-Zn-Se alloy was shown to be less cytotoxic than both the Mg-Zn-Cu and Mg-Zn alloys. PMID:24058329

  8. Biocompatibility Assessment of Novel Bioresorbable Alloys Mg-Zn-Se and Mg-Zn-Cu for Endovascular Applications: In- Vitro Studies.

    PubMed

    Persaud-Sharma, Dharam; Budiansky, Noah; McGoron, Anthony J

    2013-01-01

    Previous studies have shown that using biodegradable magnesium alloys such as Mg-Zn and Mg-Zn-Al possess the appropriate mechanical properties and biocompatibility to serve in a multitude of biological applications ranging from endovascular to orthopedic and fixation devices. The objective of this study was to evaluate the biocompatibility of novel as-cast magnesium alloys Mg-1Zn-1Cu wt.% and Mg-1Zn-1Se wt.% as potential implantable biomedical materials, and compare their biologically effective properties to a binary Mg-Zn alloy. The cytotoxicity of these experimental alloys was evaluated using a tetrazolium based- MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and a lactate dehydrogenase membrane integrity assay (LDH). The MTS assay was performed on extract solutions obtained from a 30-day period of alloy immersion and agitation in simulated body fluid to evaluate the major degradation products eluted from the alloy materials. Human foreskin fibroblast cell growth on the experimental magnesium alloys was evaluated for a 72 hour period, and cell death was quantified by measuring lactate dehydrogenase concentrations. Both Mg-Zn-Se and Mg-Zn-Cu alloys exhibit low cytotoxicity levels which are suitable for biomaterial applications. The Mg-Zn-Cu alloy was found to completely degrade within 72 hours, resulting in lower human foreskin fibroblast cell viability. The Mg-Zn-Se alloy was shown to be less cytotoxic than both the Mg-Zn-Cu and Mg-Zn alloys.

  9. Bioequivalence of Linagliptin 5 mg once daily and 2.5 mg twice daily: pharmacokinetics and pharmacodynamics in an open-label crossover trial.

    PubMed

    Friedrich, C; Jungnik, A; Retlich, S; Ring, A; Meinicke, T

    2014-05-01

    Linagliptin is an oral antihyperglycemic drug that acts by inhibiting the dipeptidyl peptidase-4 enzyme. A 5-mg once-daily regimen is available, but an alternative regimen was needed for twice-daily fixed-dose combinations. Although linagliptin has non-linear pharmacokinetics, simulation suggested 2.5 mg twice-daily would provide bioequivalent exposure and comparable plasma dipeptidyl peptidase-4 inhibition to 5 mg once-daily.This crossover study compared steady-state pharmacokinetics and pharmacodynamics of linagliptin 5 mg once-daily and 2.5 mg twice-daily, both administered for 7 days.In total, 16 healthy volunteers entered the study, and 15 completed both treatment periods. Exposure over 24-h at steady state (AUC0-24,ss) was similar for linagliptin 5 mg once-daily and 2.5 mg twice-daily (132 vs. 124 nmol · h/L), and the 90% confidence interval of the adjusted geometric mean ratio of AUC0-24,ss was well within the acceptance range for bioequivalence (ratio 93.9%; 90% confidence interval 89.5, 98.5). Median dipeptidyl peptidase-4 inhibition over a 24-h interval at steady state was 85.9% with linagliptin 5 mg once-daily and 86.5% with 2.5 mg twice-daily, and median dipeptidyl peptidase-4 inhibition values were approximately 80.0% at trough. Most subjects had no adverse events and there were no serious adverse events.Linagliptin 5 mg once-daily and 2.5 mg twice-daily provided bioequivalent exposure and similar inhibition of dipeptidyl peptidase-4 over the whole dosing interval.

  10. The Electrochemical Co-reduction of Mg-Al-Y Alloys in the LiCl-NaCl-MgCl2-AlF3-YCl3 Melts

    NASA Astrophysics Data System (ADS)

    Li, Mei; Liu, Yaochen; Han, Wei; Wang, Shanshan; Zhang, Milin; Yan, Yongde; Shi, Weiqun

    2015-04-01

    The electrochemical formation of Mg-Al-Y alloys was studied in the LiCl-NaCl-MgCl2 melts by the addition of AlF3 and YCl3 on a molybdenum electrode at 973 K (700 °C). In order to reduce the volatilization of salt solvent in the electrolysis process, the volatile loss of LiCl-NaCl-MgCl2 and LiCl-KCl-MgCl2 melts was first measured in the temperature range from 873 K to 1023 K (600 °C to 750 °C). Then, the electrochemical behaviors of Mg(II), Al(III), Y(III) ions and alloy formation processes were investigated by cyclic voltammetry, chronopotentiometry, and open circuit chronopotentiometry. The cyclic voltammograms indicate that the under-potential deposition of magnesium and yttrium on pre-deposited Al leads to formation of Mg-Al and Al-Y intermetallic compounds. The Mg-Al-Y alloys were prepared by galvanostatic electrolysis in the LiCl-NaCl-MgCl2-AlF3-YCl3 melts and characterized by X-ray diffraction and scanning electron microscopy with energy dispersive spectrometry. Composition of the alloys was analyzed by inductively coupled plasma-atomic emission spectrometer, and current efficiency was also determined by the alloy composition.

  11. MgCO3·3H2O and MgO complex nanostructures: controllable biomimetic fabrication and physical chemical properties.

    PubMed

    Wu, Xiaoming; Cao, Huaqiang; Yin, Gui; Yin, Jiefu; Lu, Yuexiang; Li, Baojun

    2011-03-21

    In this paper, we report a method of biomimetic synthesis of MgCO(3)·3H(2)O and MgO Viburnum opulus-like complex nanostructures with superhydrophobicity and adsorption properties. The MgCO(3)·3H(2)O complex nanostructures can be obtained by changing experimental parameters, including concentrations of reactants (dextran and MgCl(2)), molar ratios of reactants, and reaction time. The phase structure of as-synthesized samples was characterized by X-ray diffraction (XRD). The morphology and structure are studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The MgCO(3)·3H(2)O complex nanostructures exhibited superhydrophobicity, due to their unique superstructures, and was proved by the contact angle (CA) measurement. We also show that a simple calcination of these unusually shaped MgCO(3)·3H(2)O results in spontaneous formation of MgO complex nanostructures while the unique shape can be maintained, and the as-synthesized MgO nanostructures show excellent adsorption property. These unique structures and properties will open up a wide range of potential applications in material and environmental protection.

  12. Adsorption of Ar on a nonuniform MgO surface

    NASA Technical Reports Server (NTRS)

    Hinman, D. C.; Halsey, G. D.

    1976-01-01

    Data are presented for the adsorption of Ar and N2 on a strongly heterogeneous MgO surface at 84 K and for Ar at a range of temperatures between 130 and 250 K. The high-temperature data are analyzed according to a model which separates the contributions to the potential into bulk and surface terms, providing a method for the determination of the surface area from parameters characteristic of the bulk material. A solid-gas energy parameter and parameters indicating the strength of the impurity sites are also evaluated.

  13. Studies on ZnS-MgS Nano Composites

    NASA Astrophysics Data System (ADS)

    Rajkumar, M.; Raj, S. Alfred Cecil

    2011-10-01

    ZnS-MgS nanocomposites was successfully prepared by the microwave assisted solvothermal method using a domestic microwave oven. The prepared sample was annealed at 100 °C for 1 hr to improve the ordering. Grain sizes and lattice parameters were determined by carrying out X-ray powder diffraction measurements. Scanning electron microscopy (SEM) shows the morphology. AC electrical measurements were carried out on pelletised samples at various temperatures ranging from 40-150 °C. Results of the present study reveal that the space charge contribution plays a significant role in the charge transport process and polarizability.

  14. Preparation of an additive-free sample with a MgH2 phase by planetary ball milling of Mg with10 wt% MgH2

    NASA Astrophysics Data System (ADS)

    Hong, Seong-Hyeon; Song, Myoung Youp

    2016-11-01

    In order to prepare an additive-free sample with a MgH2 phase, 90 wt% Mg+10 wt% MgH2 (named Mg-10MgH2) was milled under hydrogen atmosphere in a planetary ball mill for different durations (2 h, 5 h, and 10 h). The hydrogen absorption and release properties of the prepared samples were investigated and compared with those of purchased pure MgH2 samples. Mg-10MgH2 milled for 5 h had the largest quantity of hydrogen released at 648 K for 100 min of 5.96 wt%. Mg-10MgH2 milled for 5 h released 0.11 wt% H for 10 min, 4.85 wt% H for 30 min, and 5.83 wt% H for 60 min at 648 K at the first cycle. Mg-10MgH2 milled for 5 h absorbed 5.39 wt% H for 5 min and 5.92 wt% H for 60 min at 648 K at the second cycle. Dehydriding curves were also obtained at the first cycle of Mg-10MgH2 samples milled for 5 h using Mg powder with or without sieving (200 mesh). The dehydriding curve at 648 K of a Mg-10MgH2 sample milled for 5 h in the planetary ball mill was compared with that of the sample milled for 24 h in a horizontal ball mill.

  15. New FCC Mg-Zr and Mg-Zr-ti deuterides obtained by reactive milling

    NASA Astrophysics Data System (ADS)

    Guzik, Matylda N.; Deledda, Stefano; Sørby, Magnus H.; Yartys, Volodymyr A.; Hauback, Bjørn C.

    2015-03-01

    Results for binary Mg-Zr and ternary Mg-Zr-Ti mixtures ball milled at room temperature under reactive deuterium atmosphere (5.6-6.7 MPa) are reported. X-ray and neutron powder diffraction combined with Rietveld refinements show that two new cubic phases were formed during milling. Mg0.40Zr0.60D1.78 and Mg0.40Zr0.26Ti0.34D1.98 crystallize with disordered face centered cubic metal atom arrangements. Results of differential scanning calorimetry and termogravimetric measurements demonstrate that both deuterides desorb deuterium at lower temperatures than MgD2, ZrD2 or TiD2; 528 and 575 K in the Mg-Zr-D and Mg-Zr-Ti-D system, respectively. Interestingly, Mg0.40Zr0.26Ti0.34D1.98 stores deuterium reversibly at 673 K and 10 MPa of D2.

  16. Preliminary study of the characteristics of a high Mg containing Al-Mg-Si alloy

    NASA Astrophysics Data System (ADS)

    Yan, F.; McKay, B. J.; Fan, Z.; Chen, M. F.

    2012-01-01

    An Al-20Mg-4Si high Mg containing alloy has been produced and its characteristics investigated. The as-cast alloy revealed primary Mg2Si particles evenly distributed throughout an α-Al matrix with a β-Al3Mg2 fully divorced eutectic phase observed in interdendritic regions. The Mg2Si particles displayed octahedral, truncated octahedral, and hopper morphologies. Additions of Sb, Ti and Zr had a refining influence reducing the size of the Mg2Si from 52 ± 4 μm to 25 ± 0.1 μm, 35 ± 1 μm and 34 ± 1 μm respectively. HPDC tensile test samples could be produced with a 0.6 wt.% Mn addition which prevented die soldering. Solution heating for 1 hr was found to dissolve the majority of the Al3Mg2 eutectic phase with no evidence of any effect on the primary Mg2Si. Preliminary results indicate that the heat treatment has a beneficial effect on the elongation and the UTS.

  17. Compressibility of the MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Prassides, K.; Iwasa, Y.; Ito, T.; Chi, Dam H.; Uehara, K.; Nishibori, E.; Takata, M.; Sakata, M.; Ohishi, Y.; Shimomura, O.; Muranaka, T.; Akimitsu, J.

    2001-07-01

    Considerable excitement has been caused recently by the discovery that the binary-boride system with stoichiometry MgB2 is superconducting at the remarkably high temperature of 39 K [J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, and J. Akimitsu, Nature 410, 63 (2001)]. This potentially opens the way to even higher-Tc values in a new family of superconductors with unexpectedly simple composition and structure. The simplicity in the electronic and crystal structures could allow the understanding of the physics of high-Tc superconductivity without the presence of the multitude of complicated features, associated with the cuprates. Synchrotron x-ray diffraction was used to measure the isothermal compressibility of MgB2, revealing a stiff tightly packed incompressible solid with only moderate bonding anisotropy between intralayer and interlayer directions. These results, combined with the pressure evolution of the superconducting transition temperature, Tc, establish its relation to the B and Mg bonding distances over a broad range of values.

  18. The Use of Norethindrone (2 Mg.) with Mestranol (0.1 Mg.) in Fertility Control

    PubMed Central

    Wearing, Morris P.

    1963-01-01

    Norethindrone 2 mg. with mestranol 0.1 mg. (Ortho-Novum 2 mg.) was taken in cyclic fashion for fertility control by 62 private patients through 312 cycles. Each patient was interviewed every month during the trial period. No pregnancies occurred. The most common side effects noted were breakthrough bleeding, headache, fatigue and tension, nausea and depression. Five patients left the study because of depression and one because of nausea. It is suggested that the use of norethindrone 2 mg. with mestranol 0.1 mg. be reserved for the following situations: (1) those patients who have used other methods without success and in whom a further pregnancy would, in the opinion of the family physician, create hardship; (2) those patients in whom fear of pregnancy is part of the cause of marital problems; and (3) those patients in whom the product is primarily used for the treatment of menstrual disorders. PMID:13999301

  19. Growth of MgO on multi-layered graphene and Mg in PVA matrix

    NASA Astrophysics Data System (ADS)

    Marka, Sandeep K.; Mohiddon, Md. Ahamad; Prasad, Muvva D.; Srikanth, Vadali V. S. S.

    2015-07-01

    An easy and low temperature in-situ growth of MgO micro-rods on multi-layered graphene (MLG) in poly vinyl alcohol (PVA) matrix is elucidated. MLG decked with nanosized fragments of MgO and PVA are used as the starting materials to form MgO micro-rods (width = ∼1 μm and length = ∼4 μm) and MLG filled PVA composite film. Simple solution mixing, spin coating and simple drying processes are used to obtain the PVA composite. The growth mechanism of MgO micro-rods and the role of PVA in the growth of MgO micro-rods are explained on the basis of the observed morphological, structural and phase characteristics and a further controlled synthesis experiment, respectively.

  20. Space-Based Range Safety and Future Space Range Applications

    NASA Astrophysics Data System (ADS)

    Whiteman, Donald E.; Valencia, Lisa M.; Simpson, James C.

    2005-12-01

    The National Aeronautics and Space Administration (NASA) Space-Based Telemetry and Range Safety (STARS) study is a multiphase project to demonstrate the performance, flexibility and cost savings that can be realized by using space-based assets for the Range Safety [global positioning system (GPS) metric tracking data, flight termination command and range safety data relay] and Range User (telemetry) functions during vehicle launches and landings. Phase 1 included flight testing S-band Range Safety and Range User hardware in 2003 onboard a high-dynamic aircraft platform at Dryden Flight Research Center (Edwards, California, USA) using the NASA Tracking and Data Relay Satellite System (TDRSS) as the communications link. The current effort, Phase 2, includes hardware and packaging upgrades to the S-band Range Safety system and development of a high data rate Ku-band Range User system. The enhanced Phase 2 Range Safety Unit (RSU) provided real-time video for three days during the historic GlobalFlyer (Scaled Composites, Mojave, California, USA) flight in March, 2005. Additional Phase 2 testing will include a sounding rocket test of the Range Safety system and aircraft flight testing of both systems. Future testing will include a flight test on a launch vehicle platform. This paper discusses both Range Safety and Range User developments and testing with emphasis on the Range Safety system. The operational concept of a future space-based range is also discussed.

  1. Space-Based Range Safety and Future Space Range Applications

    NASA Technical Reports Server (NTRS)

    Whiteman, Donald E.; Valencia, Lisa M.; Simpson, James C.

    2005-01-01

    The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to demonstrate the performance, flexibility and cost savings that can be realized by using space-based assets for the Range Safety (global positioning system metric tracking data, flight termination command and range safety data relay) and Range User (telemetry) functions during vehicle launches and landings. Phase 1 included flight testing S-band Range Safety and Range User hardware in 2003 onboard a high-dynamic aircraft platform at Dryden Flight Research Center (Edwards, California) using the NASA Tracking and Data Relay Satellite System as the communications link. The current effort, Phase 2, includes hardware and packaging upgrades to the S-band Range Safety system and development of a high data rate Ku-band Range User system. The enhanced Phase 2 Range Safety Unit provided real-time video for three days during the historic GlobalFlyer (Scaled Composites, Mojave, California) flight in March, 2005. Additional Phase 2 testing will include a sounding rocket test of the Range Safety system and aircraft flight testing of both systems. Future testing will include a flight test on a launch vehicle platform. This report discusses both Range Safety and Range User developments and testing with emphasis on the Range Safety system. The operational concept of a future space-based range is also discussed.

  2. Space-Based Range Safety and Future Space Range Applications

    NASA Technical Reports Server (NTRS)

    Whiteman, Donald E.; Valencia, Lisa M.; Simpson, James C.

    2005-01-01

    The National Aeronautics and Space Administration (NASA) Space-Based Telemetry and Range Safety (STARS) study is a multiphase project to demonstrate the performance, flexibility and cost savings that can be realized by using space-based assets for the Range Safety [global positioning system (GPS) metric tracking data, flight termination command and range safety data relay] and Range User (telemetry) functions during vehicle launches and landings. Phase 1 included flight testing S-band Range Safety and Range User hardware in 2003 onboard a high-dynamic aircraft platform at Dryden Flight Research Center (Edwards, California, USA) using the NASA Tracking and Data Relay Satellite System (TDRSS) as the communications link. The current effort, Phase 2, includes hardware and packaging upgrades to the S-band Range Safety system and development of a high data rate Ku-band Range User system. The enhanced Phase 2 Range Safety Unit (RSU) provided real-time video for three days during the historic Global Flyer (Scaled Composites, Mojave, California, USA) flight in March, 2005. Additional Phase 2 testing will include a sounding rocket test of the Range Safety system and aircraft flight testing of both systems. Future testing will include a flight test on a launch vehicle platform. This paper discusses both Range Safety and Range User developments and testing with emphasis on the Range Safety system. The operational concept of a future space-based range is also discussed.

  3. Kinetics of Mg partition and Mg stable isotope fractionation during its incorporation in calcite

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; Gautier, Quentin; Bosc, Olivier; Schott, Jacques

    2013-08-01

    Calcite growth experiments have been performed in the presence of aqueous Mg at 25 °C and 1 bar pCO2 to quantify magnesium partition coefficient D={(Mg/Ca)}/{(Mg/Ca)} and Mg isotope fractionation between calcite and reactive fluid (Δ26Mgcalcite-fluid) as a function of calcite precipitation rate rp (mol m-2 s-1). Mg partition coefficient, DMg, increases with calcite growth rate according to: LogD=0.2517(±0.0150)×Logrp+0.0944(±0.0182); R2=0.93,(10-8.3⩽rp⩽10-6.6molms) Δ26Mgcalcite-fluid was found to depend heavily on calcite growth rate with preferential incorporation of 24Mg in calcite and the extent of isotope fractionation decreasing with increasing calcite growth rate in accord with: Δ26Mg=0.7918(±0.0452)×Logrp+3.2366(±0.3360); R2=0.97(10-8.3⩽rp⩽10-6.6molms) The negative Δ26Mgcalcite-fluid values found in this study, with calcite overgrowths enriched in light Mg, are consistent with (i) recent experimental data on Mg isotope fractionation during low-Mg calcite homogeneous precipitation (Immenhauser et al., 2010) and magnesite growth (Pearce et al., 2012) and (ii) with theoretical values calculated for Mg-calcite by density-functional electronic structure models (Rustad et al., 2010). The deviation of the isotopic composition of precipitated Mg-calcite from the equilibrium mass fractionation line in a three isotope diagram is a linear function of calcite growth rate. The equilibrium Δ26Mgcalcite-fluid value at 25 °C derived from this linear extrapolation, Δ26Mgcalcite-fluid = -3.5 ± 0.2‰ (2σ), is in good agreement with the theoretical value calculated by Rustad et al. (2010) for Mg-calcite (Δ26Mgcalcite-fluid = -3.6‰; BP86 functional). A striking feature of the results of this study is the decrease of the extent of Mg isotope fractionation (from -3.16‰ to -1.88‰) with the increase of calcite precipitation rate (from 10-8.3 to 10-6.6 mol m-2 s-1) which is opposite to the variation of Ca, Ba and Sr isotope fractionation with calcite

  4. Dust in MG II Absorption Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, S.

    The dust absorption feature at 2175 AA is detected in a composite spectrum of Mg II absorbers. The composite absorber spectrum is obtained by taking the geometric mean of 92 quasar spectra after aligning them in the rest-frame of 96 absorbers. By aligning the spectra according to absorber redshifts we reinforce the spectral features of the absorbers, and smooth over possible bumps and wiggles in the emission spectra. The width of the observed absorption feature is 200-300 AA (FWHM), or 0.4-0.6 microns^{-1} and the central wavelength is 2240 AA. The Galactic dust feature has a central wavelength of 2176 AA and FWHM = 0.8-1.25 microns^{-1}. Simulations show that this discrepancy between the properties of the 2175 AA feature in Mg II absorbers and Galactic ISM can be mostly explained by the different methods used to measure them (cf. Malhotra 1997).

  5. Midazolam 12 mg is moderately counteracted by 250 mg caffeine in man.

    PubMed

    Mattila, M J; Vainio, P; Nurminen, M L; Vanakoski, J; Seppälä, T

    2000-12-01

    Caffeine (Caf) counteracts various effects of benzodiazepines (BZDs). Since the effects of zolpidem, a short-acting atypical GABA(A)-BZD agonist, were not antagonized by Caf, we studied an interaction between Caf and midazolam (Mid) in healthy volunteers. In Study 1, 108 healthy students divided to 6 parallel groups were given Mid 12 mg (capsule) and Caf 125 and 250 mg (in decaffeinated coffee), alone and in combinations in the double-blind placebo-controlled manner. Objective and subjective tests were done before and at 45 and 90 min after intake. Ranked delta-values (changes from baseline) were analyzed by one-way contrast ANOVA and Scheffe's tests. In Study 2, six healthy subjects took Mid 15 mg (tablet) with and without Caf 300 mg. The dynamic effects were analyzed as in Study 1 and the plasma concentrations were assayed. In Study 1, learn effects after placebo (ad + 15%) were seen for letter cancellation and digit symbol substitution tests. Midazolam alone significantly (p < 0.05 vs. delta-placebo) reduced letter cancellation and digit symbol substitution, lowered flicker fusion, impaired digit learning and caused subjective calmness on VAS. Caffeine alone did not differ from placebo objectively, yet improved quick-wittedness and contentedness on VAS. In the combinations, Mid + Caf 125 mg differed from placebo objectively as Mid alone, whereas Mid + Caf 250 mg did not. Mid + Caf 250 mg differed from Mid on digit substitution, but did not differ from Mid+Caf 150 mg in impairing memory and causing subjective sedation. In Study 2, Mid 15 mg caused sedation and Caf 300 mg increased plasma Mid at 45 min. Mid + Caf did not differ from Mid alone objectively, but did so subjectively on VAS (p > 0.05). In conclusion, in a parallel group study, sedative effects of Mid 12 mg were only moderately antagonized by Caf 250 mg but not by Caf 125 mg. In a cross-over study, a weak interaction was found subjectively but not in objective measures.

  6. MMT Survey for Intervening Mg II Absorption

    NASA Astrophysics Data System (ADS)

    Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.

    2006-05-01

    We present the results from a spectroscopic survey for intervening Mg II absorption in the spectra of 381 background QSOs conducted at the MMT telescope. This survey complements our earlier SDSS EDR Mg II survey, extending our results to lower redshift (z~=0.15) and weaker Mg II λ2796 rest equivalent width (Wλ27960~=0.1 Å). We confirm two major results from that survey: the transition in the Wλ27960 distribution at Wλ27960~0.3 Å, and the Wλ27960-dependent evolution of the incidence of systems. The nature of ∂2N/∂z∂Wλ27960 is consistent with the idea that multiple physically distinct components/processes contribute to the incidence of Mg II absorption systems in a W0-dependent manner and evolve at different rates. A significant decrease in the total proper absorption cross section is detected in our MMT data for systems as weak as 1.0 Å<=Wλ27960<1.5 Å at z<~0.4. We discuss this W0-dependent evolution in the context of the evolution of galaxy structures, processes including superwinds and interactions, and damped-Lyα absorbers. We also consider the possibility that the observed redshift and Wλ27960 dependence of the incidence of absorption in spectroscopic surveys for low-ionization/neutral gas results from the effects of dust-induced extinction. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  7. [Evaluation of efficacy of ketoconazole 800 mg-clindamycin 100 mg tablets vaginal against ketoconazole 800 mg- clindamycin 100 mg vaginal capsules in candida vaginitis and vaginosis].

    PubMed

    Martínez-García, Alfonso; Cejudo-Alvarez, José; Bravo-Topete, Enrique Gómez; Herrera-Villalobos, Javier Edmundo; Garibay-Valencia, Miguel; Mirabent-González, Felio

    2011-02-01

    pharmaceutical forms (presentations) influence treatment compliance and therefore the effectiveness. Here we present the results in the relief of vaginitis and vaginosis with two different dosage forms. To compare the efficacy and safety of a combination of ketoconazole 800 mg + clindamycin in soft vaginal gel capsules 100 mg (vaginal capsules) against ketoconazole 800 mg + 100 mg clindamycin vaginal tablets (TV) in the management of vaginitis by C. albicans and/or vaginosis. In a randomized, multicenter, comparative open label study, patients between 18 and 60 years with a diagnosis of vaginitis by C. albicans and/or vaginosis were included. Patients were evaluated clinically and direct exam of genital discharge and culture were performed. Patients were randomized to one of two treatments vaginal tablets or vaginal capsules, for 3 days. one hundred an sitxty nine patients were included, 85 in TV Group and 84 in vaginal capsules group. We found significant statistical difference in clinical response for tablet group at day three for burning p = 0.032 and itching p = 0.043. Microbiological cure was observed in patients with vaginitis by C. albicans, 92.5% in Group TV vs. 90.47% vaginal capsules group, all patients with G. vaginalis at baseline were negative for the organism at the end of the study, cure in patients with mixed infections were 78.94% for TV group vs. 78.26% vaginal capsules; group no adverse events were reported during treatment. Treatment of vaginitis/vaginosis with vaginal tablets is clinically better than vaginal soft gelatin capsules both treatments were well tolerated.

  8. The significance of Mg in prebiotic geochemistry

    PubMed Central

    Holm, N G

    2012-01-01

    Magnesium plays a special role in biochemistry because of its ability to coordinate six oxygen atoms efficiently in its first coordination shell. Such oxygen atoms may be part of one or two charged oxyanions, which means that Mg2+ can, for instance, tie together two different phosphate groups that are located at distance from each other in a macromolecule, and in this way be responsible for the folding of molecules like RNA. This property of Mg2+ also helps the stabilization of diphosphate and triphosphate groups of nucleotides, as well as promoting the condensation of orthophosphate to oligophosphates, like pyrophosphate and trimetaphosphate. Borates, on the other hand, are known to promote the formation of nucleobases and carbohydrates, ribose in particular, which is yet another constituent of nucleotides. The oldest borate minerals that we find on Earth today are magnesium borates. Dissolved borate stabilizes pentose sugars by forming complexes with cis-hydroxyl groups. In the furanose form of ribose, the preferential binding occurs to the 2 and 3 carbon, leaving the 5 carbon free for phosphorylation. The central role of Mg2+ in the function of ribozymes and its ‘archaic’ position in ribosomes, and the fact that magnesium generally has coordination properties different from other cations, suggests that the inorganic chemistry of magnesium had a key position in the first chemical processes leading to the origin and early evolution of life. PMID:22429303

  9. A preliminary study for novel use of two Mg alloys (WE43 and Mg3Gd).

    PubMed

    Guo, Yu; Liu, Weiwei; Ma, Shanshan; Wang, Jia; Zou, Jingting; Liu, Zhenzhen; Zhao, Jinghui; Zhou, Yanmin

    2016-05-01

    In this study, two types of magnesium alloys (WE43 and Mg3Gd) were compared with Heal-All membrane (a biodegradable membrane used in guided bone regeneration) in vitro to determine whether the alloys could be used as biodegradable membranes. Degradation behavior was assessed using immersion testing with simulated body fluid (SBF). Microstructural characteristics before and after immersion were evaluated through scanning electron microscopy, and degradation products were analyzed with energy dispersive spectrometry (EDS). To evaluate the biocompatibility of the three types of materials, we performed cytotoxicity, adhesion, and mineralization tests using human osteoblast-like MG63 cells. Immersion testing results showed no significant difference in degradation rate between WE43 and Mg3Gd alloys. However, both Mg alloys corroded faster than the Heal-All membrane, with pitting corrosion as the main corrosion mode for the alloys. Degradation products mainly included P- and Ca-containing apatites on the surface of WE43 and Mg3Gd, whereas these apatites were rarely detected on the surface of the Heal-All membrane. All three type of materials exhibited good biocompatibility. In the mineralization experiment, the alkaline phosphatase (ALP) activity of 10 % Mg3Gd extract was significantly higher than the extracts of the two other materials and the negative control. This study highlighted the potential of these Mg-REE alloys for uses in bone regeneration and further studies and refinements are obviously required.

  10. Zolpidem 10 mg given at daytime is not antagonized by 300 mg caffeine in man.

    PubMed

    Mattila, M J; Nurminen, M L; Vainio, P; Vanakoski, J

    1998-07-01

    Caffeine counteracts various effects of traditional benzodiazepines (BZDs). As zolpidem, a short-acting hypnotic, is an atypical GABAA-BZD agonist, we investigated when caffeine would counteract the effects of zolpidem as well. In daytime study I, zolpidem 10 mg (capsule) and caffeine 150 or 300 mg (in decaffeinated coffee) were given, alone and in combinations, to parallel groups (n = 15-17) of healthy students in double-blind and placebo-controlled manner. Objective and subjective tests were done before and 45 min and 90 min after intake. Ranked delta values (changes from baseline) were analysed by one-way contrast ANOVA and Scheffe's tests. In daytime study II, four healthy subjects took zolpidem 10 mg alone, and together with blinded caffeine 250 mg or (at -45 min) erythromycin 750 mg. Objective and subjective effects were measured and plasma zolpidem concentrations assayed at baseline and 45 min and 90 min after zolpidem intake. In study I, practice effects after placebo (ad + 30%) were seen for letter cancellation and digit symbol substitution but not for flicker fusion tests. Zolpidem alone significantly impaired (P < 0.05 vs delta placebo) letter cancellation and digit symbol substitution at 45 min and 90 min, lowered the flicker fusion threshold at 45 min, and caused subjective drowsiness, mental slowness, clumsiness and feeling of poor performance. Caffeine alone showed a non-significant trend to improve objective performance. The combined effects of zolpidem and either dose of caffeine matched those measured after zolpidem alone. Zolpidem + caffeine 300 mg was not stronger than zolpidem + caffeine 150 mg in impairing immediate memory and causing subjective sedation. In study II, zolpidem caused objective and subjective sedation; neither caffeine nor erythromycin modulated the effects of zolpidem or plasma zolpidem concentrations. The sedative effects of 10 mg of zolpidem are not antagonized by 150-300 mg of caffeine in pharmacodynamic or pharmacokinetic

  11. Zinc Binding to MG53 Protein Facilitates Repair of Injury to Cell Membranes.

    PubMed

    Cai, Chuanxi; Lin, Peihui; Zhu, Hua; Ko, Jae-Kyun; Hwang, Moonsun; Tan, Tao; Pan, Zui; Korichneva, Irina; Ma, Jianjie

    2015-05-29

    Zinc is an essential trace element that participates in a wide range of biological functions, including wound healing. Although Zn(2+) deficiency has been linked to compromised wound healing and tissue repair in human diseases, the molecular mechanisms underlying Zn(2+)-mediated tissue repair remain unknown. Our previous studies established that MG53, a TRIM (tripartite motif) family protein, is an essential component of the cell membrane repair machinery. Domain homology analysis revealed that MG53 contains two Zn(2+)-binding motifs. Here, we show that Zn(2+) binding to MG53 is indispensable to assembly of the cell membrane repair machinery. Live cell imaging illustrated that Zn(2+) entry from extracellular space is essential for translocation of MG53-containing vesicles to the acute membrane injury sites for formation of a repair patch. The effect of Zn(2+) on membrane repair is abolished in mg53(-/-) muscle fibers, suggesting that MG53 functions as a potential target for Zn(2+) during membrane repair. Mutagenesis studies suggested that both RING and B-box motifs of MG53 constitute Zn(2+)-binding domains that contribute to MG53-mediated membrane repair. Overall, this study establishes a base for Zn(2+) interaction with MG53 in protection against injury to the cell membrane. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. ReaxFF(MgH) reactive force field for magnesium hydride systems.

    PubMed

    Cheung, Sam; Deng, Wei-Qiao; van Duin, Adri C T; Goddard, William A

    2005-02-10

    We have developed a reactive force field (ReaxFF(MgH)) for magnesium and magnesium hydride systems. The parameters for this force field were derived from fitting to quantum chemical (QM) data on magnesium clusters and on the equations of states for condensed phases of magnesium metal and magnesium hydride crystal. The force field reproduces the QM-derived cell parameters, density, and the equations of state for various pure Mg and MgH(2) crystal phases as well as and bond dissociation, angle bending, charge distribution, and reaction energy data for small magnesium hydride clusters. To demonstrate one application of ReaxFF(MgH), we have carried out MD simulations on the hydrogen absorption/desorption process in magnesium hydrides, focusing particularly on the size effect of MgH(2) nanoparticles on H(2) desorption kinetics. Our results show a clear relationship between grain size and heat of formation of MgH(2); as the particle size decreases, the heat of formation increases. Between 0.6 and 2.0 nm, the heat of formation ranges from -16 to -19 kcal/Mg and diverges toward that of the bulk value (-20.00 kcal/Mg) as the particle diameter increases beyond 2 nm. Therefore, it is not surprising to find that Mg nanoparticles formed by ball milling (20-100 nm) do not exhibit any significant change in thermochemical properties.

  13. Thermodynamic analysis and experimental study on the oxidation of the Zn-Al-Mg coating baths

    NASA Astrophysics Data System (ADS)

    Su, Xuping; Zhou, Jie; Wang, Jianhua; Wu, Changjun; Liu, Ya; Tu, Hao; Peng, Haoping

    2017-02-01

    Surface oxidation of molten Zn-6Al baths containing 0.0, 3.0 and 6.0 wt. % Mg were analyzed using X-ray photoelectron spectroscopy. γ-Al2O3 is formed on the surface of the Zn-6Al bath, while MgAl2O4 and MgO occur at 460 °C in the Zn-6Al-3Mg and Zn-6Al-6Mg baths, respectively. Thermodynamic analysis on the oxidation of the Zn-Al-Mg baths was performed. Calculated phase diagrams at 460 °C and 560 °C show good agreements with the experimental results. MgO or MgAl2O4 exists in almost the entire composition range of the calculated oxidation diagrams. According to the calculation, oxidation products depend on the composition and temperature of the baths. The primary and secondary oxidation products of the Zn-Al-Mg baths can be reasonably explained by oxidation phase diagrams. Utilizing these results, the favorable practical bath melts and operating conditions can be designed.

  14. Studies on the thermoluminescence spectra and thermal stability of LiF:Mg,Cu, LiF:Mg,Cu,Na and LiF:Mg,Cu,Si

    NASA Astrophysics Data System (ADS)

    Yang, B.; Lu, Q.; Wang, S.; Townsend, P. D.

    2005-09-01

    Four thermoluminescence (TL) peaks at 60-90, 100-130, 130-180 and 180-220 °C (the main peak) were observed from LiF:Mg,Cu, LiF:Mg,Cu,Na and LiF:Mg,Cu,Si. The recorded emission bands were at 375 and 414 nm in LiF:Mg,Cu, at 379 and 424 nm in LiF:Mg,Cu,Na and 378 and 425 nm in LiF:Mg,Cu,Si. The loss of TL intensity and temperature shift of the main peak were observed in LiF:Mg,Cu, LiF:Mg,Cu,Na, LiF:Mg,Cu,Si, LiF:Mg,Cu,Na,Si and LiF:Mg as well as in LiF:Mg,Cu,P, when the sample was heated to above 270 °C. It is suggested that those are the common behaviors in the Mg doped LiF samples, if the concentration of magnesium is properly high. Those behaviors are supposed to be associated with the precipitated phase of Mg and the secondary phase - Mg/(other impurities) complex.

  15. Mg-doped congruent LiTaO3 crystal for large-aperture quasi-phase matching device.

    PubMed

    Ishizuki, Hideki; Taira, Takunori

    2008-10-13

    Mg-doped congruent composition LiTaO(3) (MgLT) crystal, which can be grown by a conventional Czochralski method, has improved properties such as transparent range, thermal conductivity, and coercive field compared to conventional undoped congruent LiTaO(3). In this paper, various properties of MgLT including Mg-doping dependence are characterized, and also compared to that of undoped congruent LiTaO(3), LiNbO(3), and Mg-doped congruent LiNbO(3), as a material of high power quasi-phase matching (QPM) device. Up to 3-mm-thick periodically poled MgLT crystal is shown to demonstrate the possibility of large-aperture QPM-MgLT devices. Subsequently, optical parametric oscillation experiments by using periodically poled MgLT are demonstrated to discuss an efficient QPM condition.

  16. Laser range profile of cones

    NASA Astrophysics Data System (ADS)

    Zhou, Wenzhen; Gong, Yanjun; Wang, Mingjun; Gong, Lei

    2016-10-01

    technology. Laser one-dimensional range profile can reflect the characteristics of the target shape and surface material. These techniques were motivated by applications of laser radar to target discrimination in ballistic missile defense. The radar equation of pulse laser about cone is given in this paper. This paper demonstrates the analytical model of laser one-dimensional range profile of cone based on the radar equation of the pulse laser. Simulations results of laser one-dimensional range profiles of some cones are given. Laser one-dimensional range profiles of cone, whose surface material with diffuse lambertian reflectance, is given in this paper. Laser one-dimensional range profiles of cone, whose surface mater with diffuse materials whose retroreflectance can be modeled closely with an exponential term that decays with increasing incidence angles, is given in this paper. Laser one-dimensional range profiles of different pulse width of cone is given in this paper. The influences of surface material, pulse width, attitude on the one-dimensional range are analyzed. The laser two-dimensional range profile is two-dimensional scattering imaging of pulse laser of target. The two-dimensional range profile of roughness target can provide range resolved information. An analytical model of two-dimensional laser range profile of cone is proposed. The simulations of two-dimensional laser range profiles of some cones are given. Laser two-dimensional range profiles of cone, whose surface mater with diffuse lambertian reflectance, is given in this paper. Laser two-dimensional range profiles of cone, whose surface mater with diffuse materials whose retroreflectance can be modeled closely with an exponential term that decays with increasing incidence angles, is given in this paper. The influence of pulse width, surface material on laser two-dimensional range profile is analyzed. Laser one-dimensional range profile and laser two-dimensional range profile are called as laser

  17. Corrosion Fatigue of Al-Zn-Mg and and Al-Mg-Li Alloys.

    DTIC Science & Technology

    1986-01-01

    surface of a sample of the Al-Zn-Mg alloy tested in 0.5 M sodium chloride, at a constant potential of -0.8 I..* xiii ..:S: Vuce ...potential of -0.8 Vuce (10OX). 20g .71 179 eL 4 0.2 mm Figure 97 The fracture surface of a sample of the Al-Zn-Mg alloy tested in 0.5 N sodium...fracture surface of a sample of the Al-Zn-Mg alloy tested in 0.5 N sodium chloride at a constant potential of-1.0 Vuce (20X). : Figure 100 The fracture

  18. Preparation and properties of amorphous MgB2/MgO superstructures: Model disordered superconductor

    NASA Astrophysics Data System (ADS)

    Siemons, W.; Steiner, M. A.; Koster, G.; Blank, D. H. A.; Beasley, M. R.; Kapitulnik, A.

    2008-05-01

    In this paper, we introduce a unique method for fabricating MgB2/MgO multilayers and demonstrate the potential for using them as a new model for disordered superconductors. In this approach, we control the annealing of the MgB2 to yield an interesting new class of disordered (amorphous) superconductors with relatively high transition temperatures. The multilayers appear to exhibit quasi-two-dimensional superconductivity with controlled anisotropy. We discuss the properties of the multilayers as the thickness of the components of the bilayers vary.

  19. Decay of a J{pi}=36+ Resonance in the 24Mg + 24Mg Reaction

    SciTech Connect

    Salsac, M.-D.; Haas, F.; Courtin, S.; Beck, C.; Rousseau, M.; Zafra, A. Sanchez I.; Algora, A.; Dombradi, Z.; Beghini, S.; Farnea, E.; Lenzi, S.; Montagnoli, G.; Scarlassara, F.; Behera, B.R.; Corradi, L.; Fioretto, E.; Gadea, A.; Latina, A.; Marginean, N.; Napoli, D.

    2005-11-21

    The narrow ({gamma}=170 keV) and high spin (J{pi}=36+) resonance in the 24Mg + 24Mg reaction at ECM= 45.7 MeV has been associated with a hyperdeformed molecular state in 48Cr. Such a description has important consequences for the resonance decay into the favored inelastic channels. Through fragment-{gamma} coincidence measurements performed ON and OFF resonance using the PRISMA-CLARA array, we have identified the 24Mg states selectively populated: the 2+ and 4+ members of the ground state band.

  20. Influence of Mg component and pressure on magnetic ordering of (Mg,Fe)O

    NASA Astrophysics Data System (ADS)

    Fujii, A.; Kondo, T.; Taniguchi, T.

    2012-12-01

    (Mg,Fe)O is the second most abundant phase in the Earth's lower mantle. Knowing the fundamental properties of (Mg,Fe)O is important to understand the Earth's materials. The relation between rhombohedral distortion and antiferromagnetic ordering in FeO have been discussed, as an end member of (Mg,Fe)O. However, it does not fully understand for (Mg,Fe)O yet because its structural transition pressure is influenced by Mg component and stress condition [e.g. Zhuravlev et al., 2007]. We should also account compositional dependence on Néel temperature [Woods and Fine, 1969; Fujii et al., 2011] and spin glass-like behavior [Abbas and Hicks, 1990; Jing et al., 1993]. In this study, we investigated the compositional dependence of magnetic ordering at ambient pressure, and pressure dependence of Néel temperature up to 1.27 GPa. Superconducting Quantum Interference Device (SQUID, MPMS-7, Quantum design) was used for all magnetic measurements. We measured the temperature dependence of susceptibilities cooling with in zero field (ZFC) and in a field (FC) at ambient pressure and observed splitting between susceptibility of ZFC and FC. We confirmed that the smaller compositional dependence on Néel temperature in (Mg1-XFeX)O (X ≤ 0.60) [Fujii et al., 2011] may be explained by spin-glass transition. The transition temperature of (Mg0.40Fe0.60)O is 82 K and is close to 76 K that observed in (Mg0.23Fe0.77)0.92O [Abbas and Hicks, 1990]. The spin-glass like behavior does not affect on the Néel temperature of (Mg1-XFeX)O (X ≥ 0.70) suggested by previous work [Fujii et al., 2011] because spin-glass transition temperature would not exceed 82 K. We also measured the pressure dependence of Néel temperature of (Mg0.30Fe0.70)O, (Mg0.25Fe0.75)O and (Mg0.20Fe0.80)O using a piston cylinder type pressure cell. We calibrated pressure by superconducting transition of tin. Néel temperature of (Mg,Fe)O were increased with increasing pressure except for some measurements under non

  1. Thermodynamic calculations of Fe–Mg interdiffusion in (Mg,Fe){sub 2}SiO{sub 4} polymorphs and perovskite

    SciTech Connect

    Zhang, Baohua Shan, Shuangming

    2015-02-07

    In this study, we show that the temperature and pressure dependence of Fe–Mg interdiffusion in (Fe,Mg){sub 2}SiO{sub 4} polymorphs (olivine, wadsleyite, and ringwoodite) and perovskite can be successfully reproduced in terms of bulk elastic and expansivity data through a thermodynamic model (so-called cBΩ model) that interconnects point defect parameters with bulk properties. Under dry and wet conditions, our calculated Fe–Mg interdiffusion coefficients D{sub calc}{sup Fe-Mg} (particularly for anisotropic diffusivity in olivine), activation enthalpy h{sup act}, and activation volume υ{sup act} over a wide range of geologically relevant temperatures (1000–2400 K) and pressures (0–100 GPa) are consistent with the experimental ones when the uncertainties are considered.

  2. Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2 + (1 - y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4.MgSO4(aq) at 298.15 K

    SciTech Connect

    Miladinovic, J; Ninkovic, R; Todorovic, M; Rard, J A

    2007-06-06

    Isopiestic vapor pressure measurements were made for {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions with MgCl{sub 2} ionic strength fractions of y = 0, 0.1997, 0.3989, 0.5992, 0.8008, and (1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements for the mixtures cover the ionic strength range I = 0.9794 to 9.4318 mol {center_dot} kg{sup -1}. In addition, isopiestic measurements were made with NaCl(aq) as reference standard for mixtures of {l_brace}xNa{sub 2}SO{sub 4} + (1-x)MgSO{sub 4}{r_brace}(aq) with the molality fraction x = 0.50000 that correspond to solutions of the evaporite mineral bloedite (astrakanite), Na{sub 2}Mg(SO{sub 4}){sub 2} {center_dot} 4H{sub 2}O(cr). The total molalities, m{sub T} = m(Na{sub 2}SO{sub 4}) + m(MgSO{sub 4}), range from m{sub T} = 1.4479 to 4.4312 mol {center_dot} kg{sup -1} (I = 5.0677 to 15.509 mol {center_dot} kg{sup -1}), where the uppermost concentration is the highest oversaturation molality that could be achieved by isothermal evaporation of the solvent at 298.15 K. The parameters of an extended ion-interaction (Pitzer) model for MgCl2(aq) at 298.15 K, which were required for an analysis of the {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) mixture results, were evaluated up to I = 12.025 mol {center_dot} kg{sup -1} from published isopiestic data together with the six new osmotic coefficients obtained in this study. Osmotic coefficients of {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions from the present study, along with critically-assessed values from previous studies, were used to evaluate the mixing parameters of the extended ion-interaction model.

  3. Silicon and magnesium diffusion in a single crystal of MgSiO3 perovskite

    NASA Astrophysics Data System (ADS)

    Xu, Junshan; Yamazaki, Daisuke; Katsura, Tomoo; Wu, Xiaoping; Remmert, Patrick; Yurimoto, Hisayoshi; Chakraborty, Sumit

    2011-12-01

    Si and Mg self-diffusion coefficients were measured simultaneously in single crystals of MgSiO3 perovskite under lower mantle conditions. There is little difference in Si volume diffusivity measured directly using single crystals (this study) and those retrieved from experiments with polycrystals (earlier studies). This agreement between studies establishes the reliability of Si diffusion coefficients measured in perovskite. Within the uncertainties of our measurements, no anisotropy in the diffusion of either Si or Mg could be resolved. Diffusion of Si and Mg in perovskite are described by an Arrhenius equation, D = D0 exp (-ΔH/RT) at 25 GPa, with D0 = 5.10 × 10-11 m2/s for Si and 4.99 × 10-11 m2/s for Mg, ΔH = 308 kJ/mol for Si, and 305 kJ/mol for Mg. Mg diffusivity in MgSiO3 perovskite is distinctly lower than those measured in olivine, wadsleyite, and ringwoodite. We find that Mg has very similar diffusivity to Si in perovskite. As a consequence, the rheological properties of the lower mantle may be controlled by the coupled motion of Si and Mg. A point defect-based model is discussed that may account for the diffusion behavior of Si and Mg in MgSiO3 perovskite. Our data indicate that, within realistic ranges of temperature, grain size, and state of stress, both diffusion creep as well as dislocation creep may be observed in the lower mantle.

  4. Thermodynamic studies and the phase diagram of the Li-Mg system

    SciTech Connect

    Gasior, W.; Moser, Z.; Zakulski, W.; Schwitzgebel, G.

    1996-09-01

    By means of the electromotive force (emf) method of concentration cells of the following scheme: Li (1)/LiCl-LiF (eut) or LiCi-KCl (eut)/Li-Mg (1) or Li (1)/LiCl-LiF (eut)/Li-Mg (s). Li activities for liquid and solid alloys at the (Mg), (Li), and (Mg) + (Li) two-phase region of the Li-Mg system were determined. Liquid alloys were examined at temperatures from 638 to 889 K at various Li concentrations. The (Mg) solid solutions were investigated in two series: at constant temperatures between 773 and 876 K, with varying Li content, and at fixed Li concentrations, equal to 0.125 and 0.160 molar fractions, at different temperatures between 772 and 849 K. At the two-phase region, (Mg) + (Li), emf measurements were performed in the temperature range 773 to 838 K, with fixed Li concentrations equal to 0.20, 0.25, and 0.275 molar fractions. For (Li) solid alloys, experiments were done at temperatures 773 to 849 K for several constant Li concentrations, between 0.30 and 0.45 molar fractions, respectively. Studies on solid alloys enabled the authors also to determine the boundaries (Li)/[(Mg) + (Li)] and (Mg)/[(Mg) + (Li)] at temperatures 773 to 831 K. The resulting thermodynamic and phase boundary data of this study were used with other selected references for a critical assessment of the Li-Mg system. The Lukas BINGSS optimization program and BINFKT for the calculation of the thermodynamic functions and of the phase diagram were used. The calculated equilibrium phase diagram at temperatures below 750 K indicates a slightly lower solid solubility of Mg in (Li) in comparison with results from thermal analysis and the recently published Saunders evaluation.

  5. Thermodynamic studies and the phase diagram of the Li-Mg system

    NASA Astrophysics Data System (ADS)

    Gasior, W.; Moser, Z.; Zakulski, W.; Schwitzgebel, G.

    1996-09-01

    By means of the electromotive force (emf) method of concentration cells of the following scheme: Li (1) / LiCl-LiF (eut) or LiCi-KCl (eut) / Li-Mg (1) or Li (1) / LiCl-LiF (eut) / Li-Mg (s) Li activities for liquid and solid alloys at the (Mg), (Li), and (Mg) + (Li) two-phase region of the Li-Mg system were determined. Liquid alloys were examined at temperatures from 638 to 889 K at various Li concentrations. The (Mg) solid solutions were investigated in two series: at constant temperatures between 773 and 876 K, with varying Li content, and at fixed Li concentrations, equal to 0.125 and 0.160 molar fractions, at different temperatures between 772 and 849 K. At the two-phase region, (Mg) + (Li), emf measurements were performed in the temperature range 773 to 838 K, with fixed Li concentrations equal to 0.20, 0.25, and 0.275 molar fractions. For (Li) solid alloys, experiments were done at temperatures 773 to 849 K for several constant Li concentrations, between 0.30 to 0.45 molar fractions, respectively. Studies on solid alloys enabled us also to determine the boundaries (Li)/[(Mg) + (Li)] and (Mg)/[(Mg) + (Li)] at temperatures 773 to 831 K. The resulting thermodynamic and phase boundary data of this study were used with other selected references for a critical assessment of the Li-Mg system. The Lukas BINGSS optimization program and BINFKT for the calculation of the thermodynamic functions and of the phase diagram were used. The calculated equilibrium phase diagram at temperatures below 750 K indicates a slightly lower solid solubility of Mg in (Li) in comparison with results from thermal analysis and the recently published Saunders evaluation.

  6. Influence of ion beam assisted deposition parameters on the growth of MgO and CoFeB

    SciTech Connect

    Ferreira, Ricardo; Freitas, Paulo P.; Petrova, Rumyana; McVitie, Stephen

    2012-04-01

    The effect of the kinetic parameters of an assistance ion beam on the crystallization of ion beam deposited MgO was investigated. It is shown that the crystallization of MgO in the as-deposited state is strongly dependent on the assistance beam parameters. Furthermore, two deposition regimes corresponding to different ranges of the assistance beam energy are found. XRD and TEM studies of CoFeB/MgO/CoFeB with MgO deposited in the two regimes show that CoFeB crystallization is favored when low energy assist beams are used, despite no differences being found in the MgO.

  7. A first-principles study of the thermodynamic and electronic properties of Mg and MgH2 nanowires.

    PubMed

    Wu, Xinxing; Zhang, Ruiqi; Yang, Jinlong

    2016-07-28

    In this article, we studied the thermodynamic and electronic properties of Mg and MgH2 nanowires with different diameters, and elucidated why MgH2 nanowires are good hydrogen storage materials through first-principles calculations. Previous experiments have shown that the orientation relationship between Mg and MgH2 nanowires is the Mg[0001] direction parallel to the MgH2[110] direction. In our calculations, Mg nanowires oriented along the [0001] direction and MgH2 nanowires oriented along the [110] direction were built from bulk Mg and MgH2 crystals, respectively. We found that as the diameters of Mg and MgH2 nanowires decrease, Mg and MgH2 nanowires become more unstable, and the hydrogen desorption energies and temperatures of MgH2 nanowires decrease. That is, the thinner the MgH2 nanowires get, the more dramatically hydrogen desorption temperatures (Td) will decrease. Meanwhile, we also found that when the diameters of MgH2 nanowires are larger than 1.94 nm, the Td almost maintain the same value at about 440 K, only about 40 K lower than that of bulk MgH2 crystal; if the diameters are less than 1.94 nm, the Td reduce very quickly. In particular, compared with bulk MgH2 crystal, the Td of the thinnest MgH2 nanowire with a diameter of 0.63 nm can be reduced by 164 K. In addition, the electronic structure calculations showed that Mg nanowires are metals, while MgH2 nanowires are semiconductors. In particular, our results showed that the electronic structures of MgH2 nanowires are influenced by the surface effect and quantum size effect. That is to say, the band gaps of MgH2 nanowires are controlled by surface electronic states and the size of MgH2 nanowires.

  8. Review: the effects of secular variation in seawater Mg/Ca on marine biocalcification

    NASA Astrophysics Data System (ADS)

    Ries, J. B.

    2009-07-01

    Synchronized transitions in the polymorph mineralogy of the major reef-building and sediment-producing calcareous marine organisms and abiotic CaCO3 precipitates (ooids, marine cements) throughout Phanerozoic time is believed to have been caused by tectonically-induced variations in seawater molar Mg/Ca (>2="aragonite seas"; <2="calcite seas"). Here, I review a series of experiments in which extant calcifying taxa were reared in experimental seawater formulated over the range of mMg/Ca ratios (1.0 to 5.2) that occurred throughout their geologic history. Aragonite-secreting bryopsidalean algae and scleractinian corals and calcite-secreting coccolithophores exhibited higher rates of calcification and growth in the experimental seawaters that favored their skeletal mineral. These results support the assertion that seawater Mg/Ca played an important role in determining which hypercalcifying marine organisms were the major reef-builders and sediment-producers throughout Earth history. The observation that primary production increased along with calcification in mineralogically-favorable seawater is consistent with the hypothesis that calcification promotes photosynthesis within autotrophs through the liberation of CO2. The Mg/Ca ratio of calcite secreted by the coccolithophores, coralline algae and reef-dwelling animals (crustacea, urchins, calcareous tube worms) declined with reductions in seawater Mg/Ca. Calcifying microbial biofilms varied their mineral polymorph with seawater Mg/Ca (mMg/Ca<2=low Mg calc; mMg/Ca>2=arag+high Mg calc), suggesting a nearly abiotic mode of calcification. These results indicate that biomineralogical control can be partially overridden by ambient seawater Mg/Ca and suggests that modern high Mg calcite organisms probably secreted low Mg calcite in calcite seas of the past. Notably, Mg fractionation in autotrophic organisms was more strongly influenced by changes in seawater Mg/Ca, a probable consequence of them inducing a less controlled

  9. Pulsed laser micromachining of Mg-Cu-Gd bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Kai; Lee, Ching-Jen; Hu, Ting-Ting; Li, Chun-Han; Huang, J. C.

    2012-06-01

    Micromachining of Mg-based bulk metallic glasses (BMGs) is performed using two kinds of pulsed nanosecond lasers: a 355 nm ultraviolet (UV) laser and a 1064 nm infrared (IR) laser. Precision machining on the micrometer scale and the preservation of amorphous or short-range order characteristics are important for the application of BMGs in micro-electro-mechanical systems. A higher micromachining rate is achieved using the UV laser than using the IR laser due to a better absorption rate of the former by Mg-based BMGs and a higher photon energy. The cutting depth of Mg-based BMGs ranges from 1 to 80 μm depending on the laser parameters. By appropriate adjustment of the laser power and scan speed, successful machining of the Mg-based BMG with preservation of the amorphous phase is achieved after the laser irradiation process. Short-pulse laser cutting represents a suitable alternative for machining of micro components.

  10. Impact of Mg content on native point defects in Mg{sub x}Zn{sub 1−x}O (0 ≤ x ≤ 0.56)

    SciTech Connect

    Perkins, J.; Foster, G. M.; Myer, M.; Mehra, S.; Chauveau, J. M.; Hierro, A.; Windl, W.; Brillson, L. J.

    2015-06-01

    We used depth-resolved cathodoluminescence spectroscopy and surface photovoltage spectroscopy to measure the densities, energy levels, and spatial distributions of zinc/magnesium cation and oxygen vacancies in isostructural, single-phase, non-polar Mg{sub x}Zn{sub 1−x}O alloys over a wide (0 ≤ x ≤ 0.56) range. Within this wide range, both defect types exhibit strong Mg content-dependent surface segregation and pronounced bulk density minima corresponding to unit cell volume minima, which can inhibit defect formation due to electrostatic repulsion. Mg in ZnO significantly reduces native defect densities and their non-polar surface segregation, both major factors in carrier transport and doping of these oxide semiconductors.

  11. Growth of rocksalt-structured Mg x Zn1- x O (x > 0.5) films on MgO substrates and their deep-ultraviolet luminescence

    NASA Astrophysics Data System (ADS)

    Kaneko, Kentaro; Onuma, Takeyoshi; Tsumura, Keiichi; Uchida, Takayuki; Jinno, Riena; Yamaguchi, Tomohiro; Honda, Tohru; Fujita, Shizuo

    2016-11-01

    Single-phase rocksalt-structured Mg x Zn1- x O (x > 0.5) alloy films were grown on MgO substrates using the mist chemical vapor deposition method. A specular surface with a step and terrace structure was obtained. The bandgap was tuned from 5.9 to 7.8 eV as x varied from 0.5 to 1. Deep ultraviolet cathodoluminescence, stemming from near band edge transitions, was observed for Mg0.57Zn0.43O in the 4.8-5.5 eV range, peaking at ˜5.1 eV (˜240 nm) in the 12-100 K range.

  12. Multiparticle-multihole states in 31Mg and 33Mg: A critical evaluation

    NASA Astrophysics Data System (ADS)

    Neyens, Gerda

    2011-12-01

    The experiments that provide information about the level structure of the “island of inversion” isotopes 31Mg and 33Mg are reviewed. Since the model-independent measurement of their ground-state spins was done, much experimental data can be reinterpreted, and spins and parities can be assigned to their excited states. Both experimental level schemes are found in very good agreement with calculations based on antisymmetrized molecular dynamics combined with the generator coordinate method. These calculations predict that both ground states are dominated by 2ℏω neutron excitations (more than 85% of the wave function). In the case of 33Mg, the energy of the 1ℏω and 3ℏω levels are calculated about 400 keV too high with respect to the ground state, while in 31Mg the 1ℏω levels are calculated only 200 keV too high. New key experiments are suggested.

  13. Mg intercalation in layered and spinel host crystal structures for Mg batteries.

    PubMed

    Emly, Alexandra; Van der Ven, Anton

    2015-05-04

    We investigate electrochemical properties of Mg in layered and spinel intercalation compounds from first-principles using TiS2 as a model system. Our calculations predict that Mg(x)TiS2 in both the layered and spinel crystal structures exhibits sloping voltage profiles with steps at stoichiometric compositions due to Mg-vacancy ordering. Mg ions are predicted to occupy the octahedral sites in both layered and spinel TiS2 with diffusion mediated by hops between octahedral sites that pass through adjacent tetrahedral sites. Predicted migration barriers are substantially higher than typical Li-migration barriers in intercalation compounds. The migration barriers are shown to be very sensitive to lattice parameters of the host crystal structure. We also discuss the possible role of rehybridization between the transition metal and the anion in affecting migration barriers.

  14. Auger recombination rates in ZnMgO from first principles

    NASA Astrophysics Data System (ADS)

    Heinemann, Markus; Heiliger, Christian

    2011-10-01

    We investigate direct electron-electron-hole interband Auger recombination for wurtzite Zn1-xMgxO alloys in the range 0 ≤ x ≤ 1. Recombination rates are computed by interpolating the band structure and transition matrix elements from ab initio calculations of bulk ZnO, Zn0.5Mgn0.5O, and MgO primitive cells. We find that interband Auger recombination is most probable for Mg concentrations around 50%, where ZnMgO does not exist in a stable wurtzite phase. Since, for low Mg concentrations, the calculated Auger coefficients are far below 10-32 cm6/s, we do not expect significant nonradiative loss through direct interband recombination in wurtzite ZnMgO.

  15. Point defects and magnetic properties of neutron irradiated MgO single crystal

    NASA Astrophysics Data System (ADS)

    Cao, Mengxiong; Ma, Yaru; Wang, Xingyu; Ma, Chunlin; Zhou, Weiping; Wang, Xiaoxiong; Tan, Weishi; Du, Jun

    2017-05-01

    (100)-oriented MgO single crystals were irradiated to introduce point defects with different neutron doses ranging from 1.0×1016 to 1.0×1020 cm-2. The point defect configurations were studied with X-ray diffuse scattering and UV-Vis absorption spectra. The isointensity profiles of X-ray diffuse scattering caused by the cubic and double-force point defects in MgO were theoretically calculated based on the Huang scattering theory. The magnetic properties at different temperature were measured with superconducting quantum interference device (SQUID). The reciprocal space mappings (RSMs) of irradiated MgO revealed notable diffuse scattering. The UV-Vis spectra indicated the presence of O Frenkel defects in irradiated MgO. Neutron-irradiated MgO was diamagnetic at room temperature and became ferromagnetic at low temperature due to O Frenkel defects induced by neutron-irradiation.

  16. Optical properties of Mg-doped VO{sub 2}: Absorption measurements and hybrid functional calculations

    SciTech Connect

    Hu Shuanglin; Li, S.-Y.; Granqvist, C. G.; Niklasson, G. A.; Ahuja, R.; Scheicher, R. H.; Hermansson, K.

    2012-11-12

    Mg-doped VO{sub 2} thin films with thermochromic properties were made by reactive DC magnetron co-sputtering onto heated substrates, and spectral absorption was recorded at room temperature in the 0.5 < h{omega} < 3.5 eV energy range. Clear evidence was found for a widening of the main band gap from 1.67 to 2.32 eV as the Mg/(V + Mg) atomic ratio went from zero to 0.19, thereby significantly lowering the luminous absorption. This technologically important effect could be reconciled with spin-polarized density functional theory calculations using the Heyd-Scuseria-Ernzerhof [Heyd et al., J. Chem. Phys. 118, 8207 (2003); ibid. 124, 219906 (2006)] hybrid functional. Specifically, the calculated luminous absorptance decreased when the Mg/(V + Mg) ratio was increased from 0.125 to 0.250.

  17. Object Recognition Using Range Images.

    DTIC Science & Technology

    1985-12-01

    Modeling the Dropouts in Range Images 28 Repairing the Pixel Dropouts 33 III. Recognizing Objects from Range Scenes 38 Using Range Geometry for Scene...well as possible methods of correcting for these effects. Other factors af- fecting the correlation coefficient that were considered were pixel dropouts ...and the beam spot size of the laser. Pixel dropouts were shown to be detrimental to a range image’s correlation coefficient, but could be corrected

  18. Porous Ceramic Composite ZrO2(MgO)-MgO for Osteoimplantology

    NASA Astrophysics Data System (ADS)

    Buyakov, A. S.; Kulkov, S. N.

    2017-02-01

    Pore and crystalline structure, biocompatibility of ceramic composite ZrO2(MgO)-MgO were studied. The main mechanical characteristics were determined and it has been shown that compression strength directly depends on microstresses obtained from X-ray data. In-vitro studies of mesenchymal stromal stem cells (MMSC), cultivated on material surface are shown that cell proliferation and differentiation of MMSC goes throw osteogenic type.

  19. Using evidence from different sources: an example using paracetamol 1000 mg plus codeine 60 mg

    PubMed Central

    Smith, Lesley A; Moore, R Andrew; McQuay, Henry J; Gavaghan, David

    2001-01-01

    Background Meta-analysis usually restricts the information pooled, for instance using only randomised, double-blind, placebo-controlled trials. This neglects other types of high quality information. This review explores using different information for the combination of paracetamol 1000 mg and codeine 60 mg in acute postoperative pain. Results Randomised, double-blind, placebo-controlled trials of paracetamol 1000 mg and codeine 60 mg had an NNT of 2.2 (95% confidence interval 1.7 to 2.9) for at least 50% pain relief over four to six hours in three trials with 197 patients. Computer simulation of randomised trials demonstrated 92% confidence that the simulated NNT was within ± 0.5 of the underlying value of 2.2 with this number of patients. The result was supported a rational dose-response relationship for different doses of paracetamol and codeine in 17 additional trials with 1,195 patients. Three controlled trials lacking a placebo and with 117 patients treated with of paracetamol 1000 mg and codeine 60 mg had 73% (95%CI 56% to 81%) of patients with at least 50% pain relief, compared with 57% (48% to 66%) in placebo controlled trials. Six trials in acute pain were omitted because of design issues, like the use of different pain measures or multiple dosing regimens. In each paracetamol 1000 mg and codeine 60 mg was shown to be better than placebo or comparators for at least one measure. Conclusions Different designs of high quality trials can be used to support limited information used in meta-analysis without recourse to low quality trials that might be biased. PMID:11231885

  20. Flunarizine in migraine prophylaxis: efficacy and tolerability of 5 mg and 10 mg dose levels.

    PubMed

    Centonze, V; Magrone, D; Vino, M; Caporaletti, P; Attolini, E; Campanale, G; Albano, O

    1990-02-01

    The use of flunarizine, a drug which has proven its efficacy in migraine, is often associated with important side effects. The aim of this paper has been to check their incidence at different dose levels (5 mg vs 10 mg). Our data confirm the occurrence of important side effects (in particular weight gain); on the other hand, they emphasize the dose-dependency of the side effects.

  1. Plasmons in MgB2

    NASA Astrophysics Data System (ADS)

    Chow, Paul; Caliebe, Wolfgang; Kao, Chi-Chang; Friedman, Barry

    2002-03-01

    Due to an apparent anomalously small effective coulomb interaction , it has been suggested [1] that there is a novel charge response from MgB2 in the form of acoustic plasmons. This has motivated at least two detailed calculations of plasmons in MgB2 [2,3]. Although these calculations find no indication of acoustic plasmons, there is a very interesting calculated charge response in the form of a very broad plasmon at ~20eV and an extremely sharp collective excitation with energy between 2-5 eV. Using inelastic X-ray scattering (IXS) we measured the collective charge excitations in MgB2 from oriented thin films and powder samples. The inelastic scattering from the oriented thin film was too weak to be measured, most likely indicating that the film was not sufficiently thick. The conventional plasmons near 20eV were measured in the powder sample for several values of q. In apparent disgreement with calculations [2] these plasmons persist for q of at least 1. /angstrom. We found no evidence of the calculated sharp lower energy excitation, possibly due to the low weight, insufficient resolution or directional averaging of the powder. Research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, [1] K. Voelker, V.I. Anisimov, and T.M. Rice, cond-mat/0103082 5 March 2001. [2] W. Ku, W.E. Pickett, R.T. Scalettar, and A.G. Eguiluz, cond-mat/0105389, 20 May 2001. [3] V.P. Zhukov, V.M. Silkin, E.V. Chulkov, P.M. Echenique, cond-mat/0105461, 23 May 2001.

  2. Laser cooling of MgCl and MgBr in theoretical approach

    SciTech Connect

    Wan, Mingjie; Shao, Juxiang; Huang, Duohui; Yang, Junsheng; Cao, Qilong; Jin, Chengguo; Wang, Fanhou; Gao, Yufeng

    2015-07-14

    Ab initio calculations for three low-lying electronic states (X{sup 2}Σ{sup +}, A{sup 2}Π, and 2{sup 2}Π) of MgCl and MgBr molecules, including spin-orbit coupling, are performed using multi-reference configuration interaction plus Davidson correction method. The calculations involve all-electronic basis sets and Douglas–Kroll scalar relativistic correction. Spectroscopic parameters well agree with available theoretical and experimental data. Highly diagonally distributed Franck-Condon factors f{sub 00} for A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) states for rapid laser cooling are also obtained. The proposed laser drives A{sup 2}Π{sub 3/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transition by using three wavelengths (main pump laser λ{sub 00}; two repumping lasers λ{sub 10} and λ{sub 21}). These results indicate the probability of laser cooling MgCl and MgBr molecules.

  3. Laser cooling of MgCl and MgBr in theoretical approach.

    PubMed

    Wan, Mingjie; Shao, Juxiang; Gao, Yufeng; Huang, Duohui; Yang, Junsheng; Cao, Qilong; Jin, Chengguo; Wang, Fanhou

    2015-07-14

    Ab initio calculations for three low-lying electronic states (X(2)Σ(+), A(2)Π, and 2(2)Π) of MgCl and MgBr molecules, including spin-orbit coupling, are performed using multi-reference configuration interaction plus Davidson correction method. The calculations involve all-electronic basis sets and Douglas-Kroll scalar relativistic correction. Spectroscopic parameters well agree with available theoretical and experimental data. Highly diagonally distributed Franck-Condon factors f00 for A(2)Π3/2,1/2 (υ' = 0) → X(2)Σ(+) 1/2 (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A(2)Π3/2,1/2 (υ' = 0) states for rapid laser cooling are also obtained. The proposed laser drives A(2)Π3/2 (υ' = 0) → X(2)Σ(+) 1/2 (υ″ = 0) transition by using three wavelengths (main pump laser λ00; two repumping lasers λ10 and λ21). These results indicate the probability of laser cooling MgCl and MgBr molecules.

  4. -MgO Melt by Super Gravity

    NASA Astrophysics Data System (ADS)

    Li, Juncheng; Guo, Zhancheng; Gao, Jintao; Li, Jingwei

    2014-08-01

    Perovskite phase was successfully separated from CaO-TiO2-SiO2-Al2O3-MgO melt by super gravity. Under the hypothesis that the titanium exists in the slag in terms of TiO2, with the gravity coefficient G = 600, time t = 5 minutes, and temperature T = 1563 K (1290 °C), the mass fraction of TiO2 in the concentrate is up to 52.94 pct, while that of the tailing is just 5.88 pct. The recovery ratio of Ti in the concentrate is up to 81.28 pct by centrifugal separation.

  5. The Atomization Energy of Mg4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1999-01-01

    The atomization energy of Mg4 is determined using the MP2 and CCSD(T) levels of theory. Basis set incompleteness, basis set extrapolation, and core-valence effects are discussed. Our best atomization energy, including the zero-point energy and scalar relativistic effects, is 24.6+/-1.6 kcal per mol. Our computed and extrapolated values are compared with previous results, where it is observed that our extrapolated MP2 value is good agreement with the MP2-R12 value. The CCSD(T) and MP2 core effects are found to have the opposite signs.

  6. On the dissociation energy of Mg2

    NASA Technical Reports Server (NTRS)

    Partridge, Harry; Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.; Mclean, A. D.; Liu, Bowen

    1990-01-01

    The bonding in the X 1Sigma(+)g state of Mg2 is investigated using near-complete valence one-particle Slater and Gaussian basis sets containing up to h functions. It is shown that the four-electron complete CI limit can be approached using a sequence of either second-order CI (SOCI) or interacting correlated fragment (ICF) calculations. At the valence level, the best estimate of the dissociation energy D(e) was 464/cm. This is a lower limit and is probably within 5/cm of the complete basis value.

  7. The Atomization Energy of Mg4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1999-01-01

    The atomization energy of Mg4 is determined using the MP2 and CCSD(T) levels of theory. Basis set incompleteness, basis set extrapolation, and core-valence effects are discussed. Our best atomization energy, including the zero-point energy and scalar relativistic effects, is 24.6+/-1.6 kcal per mol. Our computed and extrapolated values are compared with previous results, where it is observed that our extrapolated MP2 value is good agreement with the MP2-R12 value. The CCSD(T) and MP2 core effects are found to have the opposite signs.

  8. On the dissociation energy of Mg2

    NASA Astrophysics Data System (ADS)

    Partridge, Harry; Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.; McLean, A. D.; Liu, Bowen

    1990-05-01

    The bonding in the X 1Sigma(+)g state of Mg2 is investigated using near-complete valence one-particle Slater and Gaussian basis sets containing up to h functions. It is shown that the four-electron complete CI limit can be approached using a sequence of either second-order CI (SOCI) or interacting correlated fragment (ICF) calculations. At the valence level, the best estimate of the dissociation energy D(e) was 464/cm. This is a lower limit and is probably within 5/cm of the complete basis value.

  9. Biodegradable CaMgZn bulk metallic glass for potential skeletal application.

    PubMed

    Wang, Y B; Xie, X H; Li, H F; Wang, X L; Zhao, M Z; Zhang, E W; Bai, Y J; Zheng, Y F; Qin, L

    2011-08-01

    A low density and high strength alloy, Ca65Mg15Zn20 bulk metallic glass (CaMgZn BMG), was evaluated by both in vitro tests on ion release and cytotoxicity and in vivo implantation, aimed at exploring the feasibility of this new biodegradable metallic material for potential skeletal applications. MTT assay results showed that the experimental CaMgZn BMG extracts had no detectable cytotoxic effects on L929, VSMC and ECV304 cells over a wide range of concentrations (0-50%), whereas for MG63 cells concentrations in the range ~5-20% promoted cell viability. Meanwhile, alkaline phosphatase (ALP) activity results showed that CaMgZn BMG extracts increased alkaline phosphatase (ALP) production by MG63 cells. However, Annexin V-fluorescein isothiocyanate and propidium iodide staining indicated that higher concentrations (50%) might induce cell apoptosis. The fluorescence observation of F-actin and nuclei in MG63 cells showed that cells incubated with lower concentrations (0-50%) displayed no significant change in morphology compared with a negative control. Tumor necrosis factor-α expression by Raw264.7 cells in the presence of CaMgZn BMG extract was significantly lower than that of the positive and negative controls. Animal tests proved that there was no obvious inflammation reaction at the implantation site and CaMgZn BMG implants did not result in animal death. The cortical thickness around the CaMgZn BMG implant increased gradually from 1 to 4 weeks, as measured by in vivo micro-computer tomography.

  10. Sequential ranging: How it works

    NASA Technical Reports Server (NTRS)

    Baugh, Harold W.

    1993-01-01

    This publication is directed to the users of data from the Sequential Ranging Assembly (SRA), and to others who have a general interest in range measurements. It covers the hardware, the software, and the processes used in acquiring range data; it does not cover analytical aspects such as the theory of modulation, detection, noise spectral density, and other highly technical subjects. In other words, it covers how ranging is done, but not the details of why it works. The publication also includes an appendix that gives a brief discussion of PN ranging, a capability now under development.

  11. Superlow elastic stability of MgSO4-H2O ice

    NASA Astrophysics Data System (ADS)

    Fateev, E. G.

    2012-04-01

    A superlow elastic stability of low-saline MgSO4-H2O ice in a broad range of low temperatures (100-255 K) has been observed under the conditions of strong (0-1 GPa) uniaxial compression. The level of elastic stability of the MgSO4-H2O ice (containing a low mass fraction of MgSO4 within p = 0.0001-0.01) was 15-30 times smaller than in pure freshwater ice and also significantly lower than in NaCl-H2O solid solutions at low temperatures (100-215 K).

  12. A fundamental study on the [(μ-Cl)3Mg2(THF)6]+ dimer electrolytes for rechargeable Mg batteries†

    PubMed Central

    Cox, Jonathan T.; Hu, Dehong; Deng, Xuchu; Hu, Jianzhi; Hu, Mary Y.; Xiao, Jie; Shao, Yuyan; Tang, Keqi; Liu, Jun

    2016-01-01

    The long sought solvated [MgCl]+ species in the Mg-dimer electrolytes was characterized by soft mass spectrometry. The presented study provides an insightful understanding on the electrolyte chemistry of rechargeable Mg batteries. PMID:25562393

  13. Isothermal section of the La-Mg-Sn system at 500 °C and crystal structure of the new ternary stannide LaMgSn2

    NASA Astrophysics Data System (ADS)

    De Negri, S.; Solokha, P.; Minetti, R.; Skrobańska, M.; Saccone, A.

    2017-04-01

    The 500 °C isothermal section of the La-Mg-Sn ternary system was established by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS) and powder X-ray diffraction (XRPD) on more than fifty alloys synthesized by induction melting and annealed. A few boundary binary compounds were found to dissolve the third element, forming ternary solid solutions, among which La(MgxSn1-x)3 (0≤x≤0.14, cP4-AuCu3) is the most extended. The existence and crystal structure of three ternary compounds were confirmed, and their homogeneity ranges at 500 °C determined: La3Mg4-xSn2+x (0.12≤x≤0.40, hP9-Zr3Cu4Si2), LaMg3-xSn2 (0.33≤x≤0.78, hP34-LaMg3-xGe2) and LaMgSn (oP12-TiNiSi). The crystal structures of two novel ternary stoichiometric compounds, found during this work, were determined from powder X-ray diffraction pattern analysis and refined using the Rietveld method: La6Mg23Sn (Fm 3 bar m , cF120-Zr6Zn23Si, a =1.47107(1) nm) and LaMgSn2 (I 4 bar 2 m , tI32-LaMgSn2, a =0.83325(3) nm, c =1.24385(5) nm). The latter is the first representative of a new structure type and can be presented as composed by a complex Mg-Sn network hosting the bigger La atoms.

  14. Thermal stability and magnetic properties of MgFe2O4@ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Mallesh, S.; Prabu, D.; Srinivas, V.

    2017-05-01

    Magnesium ferrite, MgFe2O4, (MgFO) nanoparticles (NPs) have been synthesized through sol-gel process. Subsequently, as prepared particles were coated with Zinc-oxide (ZnO) layer(s) through ultrasonication process. Thermal stability, structure and magnetic properties of as-prepared (AP) and annealed samples in the temperature range of 350 °C-1200 °C have been investigated. Structural data suggests that AP MgFO NPs and samples annealed below 500 °C in air exhibit stable ferrite phase. However, α-Fe2O3 and a small fraction of MgO secondary phases appear along with ferrite phase on annealing in the temperatures range 500 °C- 1000 °C. This results in significant changes in magnetic moment for AP NPs 0.77 μB increases to 0.92 μB for 1200 °C air annealed sample. The magnetic properties decreased at intermediate temperatures due to the presence of secondary phases. On the other hand, pure ferrite phase could be stabilized with an optimum amount of ZnO coated MgFO NPs for samples annealed in the temperature range 500 °C-1000 °C with improvement in magnetic behavior compared to that of MgFO samples.

  15. The combination of amlodipine/valsartan 5/160 mg produces less peripheral oedema than amlodipine 10 mg in hypertensive patients not adequately controlled with amlodipine 5 mg

    PubMed Central

    Schrader, J; Salvetti, A; Calvo, C; Akpinar, E; Keeling, L; Weisskopf, M; Brunel, P

    2009-01-01

    Aims: To demonstrate the benefit of the combination amlodipine/valsartan 5/160 mg over amlodipine 10 mg, in producing a lower incidence of peripheral oedema for a comparable mean sitting systolic blood pressure (MSSBP) reduction. Methods: After a 4-week amlodipine 5 mg run-in phase, inadequately controlled hypertension patients (aged ≥ 55 years, MSSBP ≥ 130 and ≤ 160 mmHg) were randomised to receive amlodipine/valsartan 5/160 mg or amlodipine 10 mg for 8 weeks, followed by amlodipine/valsartan 5/160 mg for 4 weeks for all patients. Primary variables were MSSBP change from baseline to week 8 and incidence of peripheral oedema reported as an AE. Resolution of peripheral oedema was assessed 4 weeks after switching patients from amlodipine 10 mg to amlodipine/ valsartan 5/160 mg. Results: At week 8, MSSBP showed greater reduction with amlodipine/valsartan 5/160 mg than amlodipine 10 mg (least square mean: −8.01 vs.−5.95 mmHg, p<0.001 for non-inferiority and p=0.002 for superiority). Systolic control, overall BP control and systolic response rate at week 8 were significantly higher with combination than amlodipine 10 mg (34 vs. 26%; 57 vs. 50%; 36.57 vs. 27.77%, respectively). Incidence of peripheral oedema was significantly lower with the combination than amlodipine 10 mg (6.6 vs. 31.1%, p<0.001). Peripheral oedema resolved in 56% patients who switched from amlodipine 10 mg to the combination, without the loss of effect on BP reduction. Conclusion: In non-responders to amlodipine 5 mg, treatment with amlodipine/valsartan 5/160 mg induced significantly less peripheral oedema than amlodipine 10 mg for similar BP reduction. Peripheral oedema resolved in > 50% patients switching from amlodipine 10 mg to the combination. PMID:19196360

  16. Accurate analytic potential and Born-Oppenheimer breakdown functions for MgH and MgD from a direct-potential-fit data analysis.

    PubMed

    Henderson, Robert D E; Shayesteh, Alireza; Tao, Jason; Haugen, Carl C; Bernath, Peter F; Le Roy, Robert J

    2013-12-19

    New high-resolution visible Fourier transform emission spectra of the A (2)Π → X (2)Σ(+) and B' (2)Σ(+) → X (2)Σ(+) systems of (24)MgD and of the B' (2)Σ(+) → X (2)Σ(+) systems of (25,26)MgD and (25,26)MgH have been combined with earlier results for (24)MgH in a multi-isotopologue direct-potential-fit analysis to yield improved analytic potential energy and Born-Oppenheimer breakdown functions for the ground X (2)Σ(+) state of MgH. Vibrational levels of the ground state of (24)MgD were observed up to v" = 15, which is bound by only 30.6 ± 0.10 cm(-1). Including deuteride and minor magnesium isotopologue data allowed us also to determine the adiabatic Born-Oppenheimer breakdown effects in this molecule. The fitting procedure used the recently developed Morse/Long-Range (MLR) potential energy function, whose asymptotic behavior incorporates the correct inverse-power form. A spin-splitting radial correction function to take account of the (2)Σ spin-rotation interaction was also determined. Our refined value for the ground-state dissociation energy of the dominant isotopologue ((24)MgH) is D(e) = 11,104.25 ± 0.8 cm (-1), in which the uncertainty also accounts for the model dependence of the fitted D(e) values for a range of physically acceptable fits. We were also able to determine the marked difference in the well depths of (24)MgH and (24)MgD (with the deuteride potential curve being 7.58 ± 0.30 cm(-1) deeper than that of the hydride) as well as smaller well-depth differences for the minor (25,26)Mg isotopologues. This analytic potential function also predicts that the highest bound level of (24)MgD is v" = 16 and that it is bound by only 2.73 ± 0.10 cm(-1).

  17. Interdiffusion and impurity diffusion in polycrystalline Mg solid solution with Al or Zn

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Sohn, Yong Ho

    2014-01-01

    Interdiffusion and impurity diffusion in Mg binary solid solutions, Mg(Al) and Mg(Zn) were investigated at temperatures ranging from 623 to 723 K. Interdiffusion coef cients were determined via the Boltzmann Matano Method using solid-to-solid diffusion couples assembled with polycrystalline Mg and Mg(Al) or Mg(Zn) solid solutions. In addition, the Hall method was employed to extrapolate the impurity diffusion coef cients of Al and Zn in pure polycrystalline Mg. For all diffusion couples, electron micro-probe analysis was utilized for the measurement of concentration pro les. The interdiffusion coef cient in Mg(Zn) was higher than that of Mg(Al) by an order of magnitude. Additionally, the interdiffusion coef cient increased signi cantly as a function of Al content in Mg(Al) solid solution, but very little with Zn content in Mg(Zn) solid solution. The activation energy and pre-exponential factor for the average effective interdiffusion coef cient in Mg(Al) solid solution were determined to be 186.8 ( 0.9) kJ/mol and 7.69 x 10-1 ( 1.80 x 10-1) m2/s, respectively, while those determined for Mg(Zn) solid solution were 139.5 ( 4.0) kJ/mol and 1.48 x 10-3 ( 1.13 x 10-3) m2/s. In Mg, the Zn impurity diffusion coef cient was an order of magnitude higher than the Al impurity diffusion coef cient. The activation energy and pre-exponential factor for diffusion of Al impurity in Mg were determined to be 139.3 ( 14.8) kJ/mol and 6.25 x 10-5 ( 5.37 x 10-4) m2/s, respectively, while those for diffusion of Zn impurity in Mg were determined to be 118.6 ( 6.3) kJ/mol and 2.90 x 10-5 ( 4.41 x 10-5) m2/s.

  18. The magnesium isotope (δ26Mg) signature of dolomites

    NASA Astrophysics Data System (ADS)

    Geske, A.; Goldstein, R. H.; Mavromatis, V.; Richter, D. K.; Buhl, D.; Kluge, T.; John, C. M.; Immenhauser, A.

    2015-01-01

    Dolomite precipitation models and kinetics are debated and complicated due to the complex and temporally fluctuating fluid chemistry and different diagenetic environments. Using well-established isotope systems (δ18O, δ13C, 87Sr/86Sr), fluid inclusions and elemental data, as well as a detailed sedimentological and petrographic data set, we established the precipitation environment and subsequent diagenetic pathways of a series of Proterozoic to Pleistocene syn-depositional marine evaporative (sabkha) dolomites, syn-depositional non-marine evaporative (lacustrine and palustrine) dolomites, altered marine ("mixing zone") dolomites and late diagenetic hydrothermal dolomites. These data form the prerequisite for a systematic investigation of dolomite magnesium isotope ratios (δ26Mgdol). Dolomite δ26Mg ratios documented here range, from -2.49‰ to -0.45‰ (δ26Mgmean = -1.75 ± 1.08‰, n = 42). The isotopically most depleted end member is represented by earliest diagenetic marine evaporative sabkha dolomites (-2.11 ± 0.54‰ 2σ, n = 14). In comparing ancient compositions to modern ones, some of the variation is probably due to alteration. Altered marine (-1.41 ± 0.64‰ 2σ, n = 4), and earliest diagenetic lacustrine and palustrine dolomites (-1.25 ± 0.86‰ 2σ, n = 14) are less negative than sabkha dolomites but not distinct in composition. Various hydrothermal dolomites are characterized by a comparatively wide range of δ26Mg ratios, with values of -1.44 ± 1.33‰ (2σ, n = 10). By using fluid inclusion data and clumped isotope thermometry (Δ47) to represent temperature of precipitation for hydrothermal dolomites, there is no correlation between fluid temperature (∼100 to 180 °C) and dolomite Mg isotope signature (R2 = 0.14); nor is there a correlation between δ26Mgdol and δ18Odol. Magnesium-isotope values of different dolomite types are affected by a complex array of different Mg sources and sinks, dissolution/precipitation and non

  19. Laser range profile of spheres

    NASA Astrophysics Data System (ADS)

    Gong, Yanjun; Wang, Mingjun; Gong, Lei

    2016-09-01

    Profile information about a three-dimensional target can be obtained by laser range profile (LRP). A mathematical LRP model from rough sphere is presented. LRP includes laser one-dimensional range profile and laser two-dimensional range profile. A target coordinate system and an imaging coordinate system are established, the mathematical model of the range profile is derived in the imaging coordinate system. The mathematical model obtained has nothing to do with the incidence direction of laser. It is shown that the laser range profile of the sphere is independent of the incidence direction of laser. This is determined by the symmetry of the sphere. The laser range profile can reflect the shape and material properties of the target. Simulations results of LRP about some spheres are given. Laser range profile of sphere, whose surface material with diffuse lambertian reflectance, is given in this paper. Laser one-dimensional range profile of sphere, whose surface mater with diffuse materials whose retro-reflectance can be modeled closely with an exponential term that decays with increasing incidence angles, is given in this paper. Laser range profiles of different pulse width of sphere are given in this paper. The influences of geometric parameters, pulse width on the range profiles are analyzed.

  20. Multistage growth of Fe-Mg-carpholite and Fe-Mg-chloritoid, from field evidence to thermodynamic modelling

    NASA Astrophysics Data System (ADS)

    Pourteau, Amaury; Bousquet, Romain; Vidal, Olivier; Plunder, Alexis; Duesterhoeft, Erik; Candan, Osman; Oberhänsli, Roland

    2015-04-01

    We provide new insights into the prograde evolution of HP/LT meta-sedimentary rocks on the basis of detailed petrologic examination, element-partitioning analysis, and thermodynamic modelling of well-preserved Fe-Mg-carpholite- and chloritoid-bearing rocks from the Afyon zone (Anatolia). Study samples, stemming from three different areas of the metamorphic belt, include typical quartz-carpholite veins as well as quartz-free and quartz-bearing phyllites. All samples exhibit multiple stages of carpholite, whereas zoning was until now rarely documented in this type of rocks. We document continuous, and discontinuous compositional (ferro-magnesian substitution) zoning of carpholite (overall XMg = 0.27-0.73) and chloritoid (overall XMg = 0.07-0.30), as well as clear equilibrium, and disequilibrium (i.e. reaction-related) textures involving carpholite and chloritoid, which consistently account for the consistent enrichment in Mg of both minerals through time, and the progressive replacement of carpholite by chloritoid. Mg/Fe distribution coefficients calculated between carpholite and chloritoid vary widely within samples (2.2-20.0). Among this range, only values of 7-11 correlate with equilibrium textures, in agreement with data from the literature. Equilibrium phase diagrams for (NaK)FMASH rock compositions are calculated using a newly modified thermodynamic dataset, including most recent data for carpholite, chloritoid, chlorite, and white mica, as well as further refinements for Fe-carpholite, and both chloritoid end-members, as required to reproduce accurately petrologic observations (phase relations, experimental constraints, Mg/Fe partitioning). Modelling reveals that Mg/Fe partitioning between carpholite and chloritoid is greatly sensitive to temperature, and calls for a future evaluation of possible use as a thermometer, valid for blueschist-facies conditions, which has so far been missing. In addition, calculations show significant effective bulk composition

  1. Validation of the MG-DIS: a disability assessment for myasthenia gravis.

    PubMed

    Raggi, Alberto; Leonardi, Matilde; Schiavolin, Silvia; Antozzi, Carlo; Brenna, Greta; Maggi, Lorenzo; Mantegazza, Renato

    2016-05-01

    This paper is aimed to present the validation of the myasthenia gravis disability assessment (MG-DIS), a MG-specific patient-reported disability outcome measure. Consecutive MG patients were enrolled, followed-up for 12 months and administered the SF-36, the WHO disability assessment schedule (WHODAS 2.0) and the preliminary 31-item MG-DIS addressing impairments and activity limitations. Factor structure and metric properties were assessed. In total, 109 patients were enrolled: 76 were females, mean age 50, mean MG duration 10.4 years, 86 were AChR-positive. The MG-DIS was reduced to 20 items, explaining 70.6 % of the original questionnaire variance, four subscales (generalized impairment-related problems; bulbar function-related problems; mental health and fatigue-related problems; vision-related problems) and an overall disability index. The MG-DIS has good metric properties (Cronbach's alpha ranging between .808 and .930), is stable, showed to be more sensitive than the WHODAS 2.0 and SF-36 to detect group differences and longitudinal changes and was well correlated with the MG-composite (.642). The MG-DIS includes items representing ocular, generalized, bulbar and respiratory symptoms, and is therefore well-built around MG-specific features. MG-DIS can be used in clinical trials as well as in observational or epidemiological studies to characterize patients' disability level and address the amount of improvement in disability. Further studies are needed to explore the possibility of a shorter disability scale.

  2. Incorporation of Mg in Free-Standing HVPE GaN Substrates

    NASA Astrophysics Data System (ADS)

    Zvanut, M. E.; Dashdorj, J.; Freitas, J. A.; Glaser, E. R.; Willoughby, W. R.; Leach, J. H.; Udwary, K.

    2016-06-01

    Mg, the only effective p-type dopant for nitrides, is well studied in thin films due to the important role of the impurity in light-emitting diodes and high-power electronics. However, there are few reports of Mg in thick free-standing GaN substrates. Here, we demonstrate successful incorporation of Mg into GaN grown by hydride vapor-phase epitaxy (HVPE) using metallic Mg as the doping source. The concentration of Mg obtained from four separate growth runs ranged between 1016 cm-3 and 1019 cm-3. Raman spectroscopy and x-ray diffraction revealed that Mg did not induce stress or perturb the crystalline quality of the HVPE GaN substrates. Photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopies were performed to investigate the types of point defects in the crystals. The near-band-edge excitonic and shallow donor-shallow acceptor radiative recombination processes involving shallow Mg acceptors were prominent in the PL spectrum of a sample doped to 3 × 1018 cm-3, while the EPR signal was also thought to represent a shallow Mg acceptor. Detection of this signal reflects minimization of nonuniform strain obtained in the thick free-standing HVPE GaN compared with heteroepitaxial thin films.

  3. In-situ Multimodal Imaging and Spectroscopy of Mg Electrodeposition at Electrode-Electrolyte Interfaces

    DOE PAGES

    Wu, Yimin A.; Yin, Zuwei; Farmand, Maryam; ...

    2017-02-10

    We report the study of Mg cathodic electrochemical deposition on Ti and Au electrode using a multimodal approach by examining the sample area in-situ using liquid cell transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy (XAS). Magnesium Aluminum Chloride Complex was synthesized and utilized as electrolyte, where non-reversible features during in situ charging-discharging cycles were observed. During charging, a uniform Mg film was deposited on the electrode, which is consistent with the intrinsic non-dendritic nature of Mg deposition in Mg ion batteries. The Mg thin film was not dissolvable during the following discharge process. Wemore » found that such Mg thin film is hexacoordinated Mg compounds by in-situ STXM and XAS. This study provides insights on the non-reversibility issue and failure mechanism of Mg ion batteries. Also, our method provides a novel generic method to understand the in situ battery chemistry without any further sample processing, which can preserve the original nature of battery materials or electrodeposited materials. This multimodal in situ imaging and spectroscopy provides many opportunities to attack complex problems that span orders of magnitude in length and time scale, which can be applied to a broad range of the energy storage systems.« less

  4. In-situ Multimodal Imaging and Spectroscopy of Mg Electrodeposition at Electrode-Electrolyte Interfaces

    NASA Astrophysics Data System (ADS)

    Wu, Yimin A.; Yin, Zuwei; Farmand, Maryam; Yu, Young-Sang; Shapiro, David A.; Liao, Hong-Gang; Liang, Wen-I.; Chu, Ying-Hao; Zheng, Haimei

    2017-02-01

    We report the study of Mg cathodic electrochemical deposition on Ti and Au electrode using a multimodal approach by examining the sample area in-situ using liquid cell transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy (XAS). Magnesium Aluminum Chloride Complex was synthesized and utilized as electrolyte, where non-reversible features during in situ charging-discharging cycles were observed. During charging, a uniform Mg film was deposited on the electrode, which is consistent with the intrinsic non-dendritic nature of Mg deposition in Mg ion batteries. The Mg thin film was not dissolvable during the following discharge process. We found that such Mg thin film is hexacoordinated Mg compounds by in-situ STXM and XAS. This study provides insights on the non-reversibility issue and failure mechanism of Mg ion batteries. Also, our method provides a novel generic method to understand the in situ battery chemistry without any further sample processing, which can preserve the original nature of battery materials or electrodeposited materials. This multimodal in situ imaging and spectroscopy provides many opportunities to attack complex problems that span orders of magnitude in length and time scale, which can be applied to a broad range of the energy storage systems.

  5. High-pressure phases of Mg2Si from first principles

    NASA Astrophysics Data System (ADS)

    Huan, Tran Doan; Tuoc, Vu Ngoc; Le, Nam Ba; Minh, Nguyen Viet; Woods, Lilia M.

    2016-03-01

    First-principles calculations are presented to resolve the possible pressure-dependent phases of Mg2Si . Although previous reports show that Mg2Si is characterized by the cubic antifluorite F m 3 ¯m structure at low pressures, the situation at higher pressures is less clear with many contradicting results. Here we utilize several methods to examine the stability, electron, phonon, and transport properties of this material as a function of pressure and temperature. We find that Mg2Si is thermodynamically stable at low and high pressures. Between 6 and 24 GPa, Mg2Si can transform into Mg9Si5 , a defected compound, and vice versa, without energy cost. Perhaps this result is related to the aforementioned inconsistency in the structures reported for Mg2Si within this pressure range. Focusing solely on Mg2Si , we find a new monoclinic C 2 /m structure of Mg2Si , which is stable at high pressures within thermodynamical considerations. The calculated electrical conductivity and Seebeck coefficient taking into account results from the electronic structure calculations help us understand better how transport can be affected in this material by modulating pressure and temperature.

  6. In-situ Multimodal Imaging and Spectroscopy of Mg Electrodeposition at Electrode-Electrolyte Interfaces

    PubMed Central

    Wu, Yimin A.; Yin, Zuwei; Farmand, Maryam; Yu, Young-Sang; Shapiro, David A.; Liao, Hong-Gang; Liang, Wen-I; Chu, Ying-Hao; Zheng, Haimei

    2017-01-01

    We report the study of Mg cathodic electrochemical deposition on Ti and Au electrode using a multimodal approach by examining the sample area in-situ using liquid cell transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy (XAS). Magnesium Aluminum Chloride Complex was synthesized and utilized as electrolyte, where non-reversible features during in situ charging-discharging cycles were observed. During charging, a uniform Mg film was deposited on the electrode, which is consistent with the intrinsic non-dendritic nature of Mg deposition in Mg ion batteries. The Mg thin film was not dissolvable during the following discharge process. We found that such Mg thin film is hexacoordinated Mg compounds by in-situ STXM and XAS. This study provides insights on the non-reversibility issue and failure mechanism of Mg ion batteries. Also, our method provides a novel generic method to understand the in situ battery chemistry without any further sample processing, which can preserve the original nature of battery materials or electrodeposited materials. This multimodal in situ imaging and spectroscopy provides many opportunities to attack complex problems that span orders of magnitude in length and time scale, which can be applied to a broad range of the energy storage systems. PMID:28186175

  7. In-situ Multimodal Imaging and Spectroscopy of Mg Electrodeposition at Electrode-Electrolyte Interfaces.

    PubMed

    Wu, Yimin A; Yin, Zuwei; Farmand, Maryam; Yu, Young-Sang; Shapiro, David A; Liao, Hong-Gang; Liang, Wen-I; Chu, Ying-Hao; Zheng, Haimei

    2017-02-10

    We report the study of Mg cathodic electrochemical deposition on Ti and Au electrode using a multimodal approach by examining the sample area in-situ using liquid cell transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy (XAS). Magnesium Aluminum Chloride Complex was synthesized and utilized as electrolyte, where non-reversible features during in situ charging-discharging cycles were observed. During charging, a uniform Mg film was deposited on the electrode, which is consistent with the intrinsic non-dendritic nature of Mg deposition in Mg ion batteries. The Mg thin film was not dissolvable during the following discharge process. We found that such Mg thin film is hexacoordinated Mg compounds by in-situ STXM and XAS. This study provides insights on the non-reversibility issue and failure mechanism of Mg ion batteries. Also, our method provides a novel generic method to understand the in situ battery chemistry without any further sample processing, which can preserve the original nature of battery materials or electrodeposited materials. This multimodal in situ imaging and spectroscopy provides many opportunities to attack complex problems that span orders of magnitude in length and time scale, which can be applied to a broad range of the energy storage systems.

  8. Damage accumulation and annealing behavior in high fluence implanted MgZnO

    NASA Astrophysics Data System (ADS)

    Azarov, A. Yu.; Hallén, A.; Svensson, B. G.; Du, X. L.; Kuznetsov, A. Yu.

    2012-02-01

    Molecular beam epitaxy grown Mg xZn 1-xO ( x ⩽ 0.3) layers were implanted at room temperature with 150 keV 166Er + ions in a fluence range of 5 × 10 15-3 × 10 16 cm -2. Evolution of ion-induced damage and structural changes were studied by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis and time-of-flight elastic recoil detection analysis. Results show that damage production enhances in both Zn- and O-sublattices with increasing the Mg content in the MgZnO. However, MgZnO as well as pure ZnO exhibits a high degree of dynamic annealing and MgZnO can not be amorphized even at the highest ion fluence used. Annealing of heavily damaged ZnO leads to a strong surface erosion and thinning of the film. Increasing the Mg content suppresses the surface evaporation in high fluence implanted MgZnO but leads to a strong surface decomposition accompanied with a Mg-rich surface layer formation during post-implantation annealing.

  9. Microstructural, optical and magnetic properties study of nanocrystalline MgO

    NASA Astrophysics Data System (ADS)

    Choudhury, Biswajit; Choudhury, Amarjyoti

    2014-04-01

    Nanocrystalline MgO is prepared by precipitation method. It has a crystallite size of 13 nm. The particles are agglomerated with varied size ranges. N2 adsorption-desorption isotherm confirms the mesoporous structure of MgO nanoparticles with a surface area of 145 m2 g-1. MgO contains hydride related impurities as evidenced from the Fourier transform infrared (FTIR) spectroscopy results. The UV-vis absorption spectrum of MgO contains several visible absorption peaks mostly associated with oxygen vacancies. These oxygen vacancies trap electrons and form color centers such as F, F +, F 2+, F 2 2+, etc. Photoluminescence (PL) and photoluminescence excitation (PLE) results have revealed that the UV and visible emission peaks of MgO result from these color centers. MgO also exhibits room temperature ferromagnetism. Vacuum annealing, however, reduces the magnetization. Thus, the observed magnetism may not be associated with oxygen vacancies. It is the Mg vacancy which is most likely promoting ferromagnetism in nanoscale MgO.

  10. Mg-doped nano ferrihydrite—A new adsorbent for fluoride removal from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Mohapatra, M.; Hariprasad, D.; Mohapatra, L.; Anand, S.; Mishra, B. K.

    2012-03-01

    The present study evaluates synthesized Mg-doped nano ferrihydrite powder as an adsorbent for F- removal from aqueous solutions. High surface area Mg-doped ferrihydrite was prepared by co-precipitation method under controlled conditions. Samples were prepared by varying Mg content in the range of 0.39-1.12%. Preliminary test work revealed that under similar conditions, with the increase in Mg content from 0.39 to 0.98% in doped ferrihydrite, % F- adsorption increased from 66 to 91%. Hence this sample was characterized by XRD, TEM, SAED and TG-DTA. Batch adsorption experiments were carried out by varying contact time (30-480 min), initial pH (1.0-10), initial fluoride concentration (10-150 mg/L), adsorbent dose (0.5-4 g/L), temperature (20-45 °C) and Cl- or SO42- concentrations (nil to 50 mg/L). The results showed 0.98% Mg-doped ferrihydrite to be an excellent fluoride adsorbent giving maximum adsorption capacity of 64 mg/g. The time data fitted well to pseudo second order kinetic model. The isothermal data followed Langmuir model. Thermodynamic parameters confirmed the adsorption process to be spontaneous and endothermic. 89% of fluoride could be desorbed from loaded sample using 1 M NaOH.

  11. Chemical reduction kinetics of nitrate in aqueous solution by Mg/Cu bimetallic particles.

    PubMed

    Mortazavi, S B; Ramavandi, B; Moussavi, G

    2011-01-01

    Synthesized magnesium/copper (Mg/Cu) bimetallic particles have shown good potential for use in the reduction of nitrate from aqueous solutions. This study was conducted to investigate the main factors affecting the kinetics of nitrate reduction by Mg/Cu particles (<100 microm) in uncontrolled reaction conditions. The Mg/Cu bimetallic particles removed the majority of the various nitrate concentrations tested (50, 100, 150, 200 and 300 mg L(-1)) within a short period. The time required for the removal of 90.6% of the NO3(-) from a 100 mg L(-1) solution was about 20 min using 2 gL(-1) bimetallic Mg/Cu at an initial solution pH of 6. The activation energy (Ea) for nitrate reduction by Mg/Cu over the temperature range of 5 to 60 degrees C was 14.21 kJ mol(-1). The experimental results of the kinetic analysis from batch studies indicated that a higher initial nitrate concentration yielded a greater reaction-rate constant and the denitrification rate increased with increase Mg/Cu dosage.

  12. Magnesium absorption in human subjects from leafy vegetables, intrinsically labeled with stable 26Mg.

    PubMed

    Schwartz, R; Spencer, H; Welsh, J J

    1984-04-01

    Collards, turnip greens, leaf lettuce, and spinach, grown in nutrient solution so that their Mg content was 80 to 90% 26Mg, were tested in ambulant male volunteers stabilized on a constant metabolic diet. The freeze-dried vegetables were incorporated in bran muffins in which the vegetables replaced part of the bran. Bran muffins without vegetables were consumed for breakfast each day. They were also used as a standard test meal to which the vegetable muffins were compared. All subjects participated in three consecutive isotope absorption tests: one of the standard test meal and two of the vegetables. The standard test was carried out after at least 30 days on the controlled diet. Subsequent tests of vegetables followed at 4-wk intervals. Each test meal contained 30 microCi 28MgCl2 and 50 mg stable 26Mg, the latter either as the intrinsic label of a test vegetable or as 26MgCl2 in solution taken with the standard bran muffins. Net absorption of both isotopes was measured to establish exchangeability and to determine relative Mg absorption from the vegetables. Exchangeability was 90% or higher from all meals tested. Relative Mg absorption was highest from collards and least from the standard test meal. Net absorption values ranged from 40 to 60%.

  13. Magnesium absorption in human subjects from leafy vegetables, intrinsically labeled with stable /sup 26/Mg

    SciTech Connect

    Schwartz, R.; Spencer, H.; Welsh, J.J.

    1984-04-01

    Collards, turnip greens, leaf lettuce, and spinach, grown in nutrient solution so that their Mg content was 80 to 90% /sup 26/Mg, were tested in ambulant male volunteers stabilized on a constant metabolic diet. The freeze-dried vegetables were incorporated in bran muffins in which the vegetables replaced part of the bran. Bran muffins without vegetables were consumed for breakfast each day. They were also used as a standard test meal to which the vegetable muffins were compared. All subjects participated in three consecutive isotope absorption tests: one of the standard test meal and two of the vegetables. The standard test was carried out after at least 30 days on the controlled diet. Subsequent tests of vegetables followed at 4-wk intervals. Each test meal contained 30 microCi /sup 28/MgCl2 and 50 mg stable /sup 26/Mg, the latter either as the intrinsic label of a test vegetable or as /sup 26/MgCl/sub 2/ in solution taken with the standard bran muffins. Net absorption of both isotopes was measured to establish exchangeability and to determine relative Mg absorption from the vegetables. Exchangeability was 90% or higher from all meals tested. Relative Mg absorption was highest from collards and least from the standard test meal. Net absorption values ranged from 40 to 60%.

  14. A new antihypertensive agent: Maxzide (75 mg triamterene/50 mg hydrochlorothiazide).

    PubMed

    Blume, C D; Williams, R L

    1984-11-05

    The combination of potassium-sparing diuretics with hydrochlorothiazide is extensively used by hypertensive patients. In the United States, a capsule formulation containing 50 mg triamterene and 25 mg hydrochlorothiazide (Dyazide) is the most popular fixed-combination product. However, several investigators have confirmed that absorption of both the triamterene and hydrochlorothiazide components of Dyazide is markedly reduced. This reduced bioavailability may reduce its effectiveness in hypertensive patients who change from optimally bioavailable hydrochlorothiazide tablets to Dyazide capsules in an effort to correct hypokalemia. Scored tablets containing 75 mg triamterene/50 mg hydrochlorothiazide (Maxzide) have been developed using a patented parallel granulation manufacturing process and evaluated in a series of bioavailability-bioequivalence studies. The triamterene and hydrochlorothiazide components of Maxzide tablets were found to be as bioavailable as liquid preparations of the active ingredients given singly or in combination. Unlike Dyazide capsules, the hydrochlorothiazide component of Maxzide tablets was found to be absorbed to the same extent as single-entity hydrochlorothiazide tablets. These studies demonstrated that two Dyazide capsules (total of 100 mg triamterene/50 mg hydrochlorothiazide) deliver to the bloodstream approximately one-half the quantity of hydrochlorothiazide as one Maxzide (75 mg triamterene/50 mg hydrochlorothiazide) tablet or one 50 mg hydrochlorothiazide tablet. Similarly, two Dyazide capsules deliver approximately one-half the quantity of triamterene as one Maxzide tablet. The safety of Maxzide tablets (dose of one tablet a day) was then evaluated in three groups of hypertensive patients: those who previously had been given two Dyazide capsules a day, those who had received four Dyazide capsules a day, and newly diagnosed patients who had received no medication. The clinical condition of the patients who changed from two or four

  15. Electrochemical formation of Mg-Li-Ca alloys by codeposition of Mg, Li and Ca from LiCl-KCl-MgCl2-CaCl2 melts.

    PubMed

    Yan, Yong De; Zhang, Mi Lin; Xue, Yun; Han, Wei; Cao, Dian Xue; Jing, Xiao Yan; He, Li Yi; Yuan, Yi

    2009-08-07

    This work presents electrochemical formation of Mg-Li-Ca alloys via codeposition of Mg, Li and Ca on a molybdenum electrode in KCl-LiCl-MgCl(2)-CaCl(2) melts at 943 K. Cyclic voltammograms (CVs) showed that the underpotential deposition (UPD) of calcium on pre-deposited magnesium leads to the formation of a liquid Mg-Ca alloy, and the succeeding underpotential deposition of lithium on pre-deposited Mg-Ca alloy leads to the formation of a liquid Mg-Li-Ca solution. Chronopotentiometric measurements indicated that the codepositon of Mg, Li and Ca occurs at current densities more negative than -0.31 A cm(-2) in LiCl-KCl-MgCl(2) (5 wt%) melts containing 1 wt% CaCl(2). Chronoamperograms demonstrated that the onset potential for the codeposition of Mg, Li and Ca is -2.200 V, and the codeposition of Mg, Li and Ca is formed when the applied potentials are more negative than -2.200 V. X-Ray diffraction (XRD) indicated that Mg-Li-Ca alloys with different phases were formed via galvanostatic electrolysis. The microstructures of typical alpha and beta phases of Mg-Li-Ca alloys were characterized by optical microscope (OM) and scanning electron microscopy (SEM). The analysis of energy dispersive spectrometry (EDS) showed that the element Ca mainly distributes along grain boundary in Mg-Li-Ca alloys. The results of inductively coupled plasma analysis determined that the chemical compositions of Mg-Li-Ca alloys correspond with the phase structures of XRD patterns, and the lithium and calcium contents of Mg-Li-Ca alloys depend on the concentrations of MgCl(2) and CaCl(2).

  16. Toward Understanding the Roaming Mechanism in H + MgH → Mg + HH Reaction.

    PubMed

    Mauguière, Frédéric A L; Collins, Peter; Stamatiadis, Stamatis; Li, Anyang; Ezra, Gregory S; Farantos, Stavros C; Kramer, Zeb C; Carpenter, Barry K; Wiggins, Stephen; Guo, Hua

    2016-07-14

    The roaming mechanism in the reaction H + MgH →Mg + HH is investigated by classical and quantum dynamics employing an accurate ab initio three-dimensional ground electronic state potential energy surface. The reaction dynamics are explored by running trajectories initialized on a four-dimensional dividing surface anchored on three-dimensional normally hyperbolic invariant manifold associated with a family of unstable orbiting periodic orbits in the entrance channel of the reaction (H + MgH). By locating periodic orbits localized in the HMgH well or involving H orbiting around the MgH diatom, and following their continuation with the total energy, regions in phase space where reactive or nonreactive trajectories may be trapped are found. In this way roaming reaction pathways are deduced in phase space. Patterns similar to periodic orbits projected into configuration space are found for the quantum bound and resonance eigenstates. Roaming is attributed to the capture of the trajectories in the neighborhood of certain periodic orbits. The complex forming trajectories in the HMgH well can either return to the radical channel or "roam" to the MgHH minimum from where the molecule may react.

  17. Mechanical Properties of Mg-Gd and Mg-Y Solid Solutions

    NASA Astrophysics Data System (ADS)

    Kula, Anna; Jia, Xiaohui; Mishra, Raj K.; Niewczas, Marek

    2016-12-01

    The mechanical properties of Mg-Gd and Mg-Y solid solutions have been studied under uniaxial tension and compression between 4 K and 298 K (-269 °C and 25 °C). The results reveal that Mg-Gd alloys exhibit higher strength and ductility under tension and compression attributed to the more effective solid solution strengthening and grain-boundary strengthening effects. Profuse twinning has been observed under compression, resulting in a material texture with strong dominance of basal component parallel to compression axis. Under tension, twining is less active and the texture evolution is controlled mostly by slip. The alloys exhibit pronounced yield stress asymmetry and significantly different work-hardening behavior under tension and compression. Increasing of Gd and/or Y concentration leads to the reduction of the tension-compression asymmetry due to the weakening of the recrystallization texture and more balanced twinning and slip activity during plastic deformation. The results suggest that under compression of Mg-Y alloys slip is more active than twinning in comparison to Mg-Gd alloys.

  18. Toward understanding the roaming mechanism in H + MgH → Mg + HH reaction

    DOE PAGES

    Mauguiere, Frederic A. L.; Collins, Peter; Stamatiadis, Stamatis; ...

    2016-02-26

    The roaming mechanism in the reaction H + MgH →Mg + HH is investigated by classical and quantum dynamics employing an accurate ab initio threedimensional ground electronic state potential energy surface. The reaction dynamics are explored by running trajectories initialized on a four-dimensional dividing surface anchored on three-dimensional normally hyperbolic invariant manifold associated with a family of unstable orbiting periodic orbits in the entrance channel of the reaction (H + MgH). By locating periodic orbits localized in the HMgH well or involving H orbiting around the MgH diatom, and following their continuation with the total energy, regions in phase spacemore » where reactive or nonreactive trajectories may be trapped are found. In this way roaming reaction pathways are deduced in phase space. Patterns similar to periodic orbits projected into configuration space are found for the quantum bound and resonance eigenstates. Roaming is attributed to the capture of the trajectories in the neighborhood of certain periodic orbits. As a result, the complex forming trajectories in the HMgH well can either return to the radical channel or “roam” to the MgHH minimum from where the molecule may react.« less

  19. Apollo 15 Mg- and Fe-norites - A redefinition of the Mg-suite differentiation trend

    NASA Astrophysics Data System (ADS)

    Lindstrom, M. M.; Marvin, U. B.; Mittlefehldt, D. W.

    The Apollo 15 highland rocks from the Apennine Front include clasts of mafic plutonic rocks from deep in the lunar crust that were brought to the surface by the Imbrium and Serenitatis impacts. The Apollo 15 norites exhibit wide variations in mineral and bulk compositions and include Fe-norites that plot between the three major pristine rock fields on a diagram of Mg' in mafic minerals vs An in paglioclase. Based on assemblages and compositions of minerals, and on ratios of elemental abundances, it is concluded that these Apollo 15 Fe-norites are differentiated members of the Mg-norite suite. The Apollo 15 and 17 norites and troctolites form a closely related suite of rocks, whose variations in mineral compositions represent the main differentiation trend of the Mg-suite. This trend in mineral compositions has a steeper slope than the previous Mg-suite field. The parent magmas for these Mg-suite rocks formed by partial melting deep in the lunar mantle. Differentiation by fractional crystallization may also have included assimilation of crustal components as the magmas rose from the mantle and crystallized plutons in the lower crust.

  20. Refinements in an Mg/MgH2/H2O-Based Hydrogen Generator

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew; Huang, Yuhong

    2010-01-01

    Some refinements have been conceived for a proposed apparatus that would generate hydrogen (for use in a fuel cell) by means of chemical reactions among magnesium, magnesium hydride, and steam. The refinements lie in tailoring spatial and temporal distributions of steam and liquid water so as to obtain greater overall energy-storage or energy-generation efficiency than would otherwise be possible. A description of the prior art is prerequisite to a meaningful description of the present refinements. The hydrogen-generating apparatus in question is one of two versions of what was called the "advanced hydrogen generator" in "Fuel-Cell Power Systems Incorporating Mg-Based H2 Generators" (NPO-43554), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 52. To recapitulate: The apparatus would include a reactor vessel that would be initially charged with magnesium hydride. The apparatus would exploit two reactions: The endothermic decomposition reaction MgH2-->Mg + H2, which occurs at a temperature greater than or equal to 300 C, and The exothermic oxidation reaction MgH2 + H2O MgO + 2H2, which occurs at a temperature greater than or equal to 330 C.

  1. Pharmacokinetics of levonorgestrel 0.75 mg tablets.

    PubMed

    Kook, Karin; Gabelnick, Henry; Duncan, Gordon

    2002-07-01

    This study examined plasma levonorgestrel (LNG) concentrations and pharmacokinetics following oral administration of a single LNG 0.75 mg tablet. Sixteen healthy female volunteers 19-44 years old enrolled in the study. Serial blood samples were drawn over 72 h after dosing in a fasting state. A gas chromatographic, negative ionization mass spectrometric detection analytical method was used to determine plasma LNG concentrations. The observed mean peak plasma LNG concentration was 14.1 +/- 7.9 ng/mL (range 6.7-39.0 ng/mL). The mean time of peak concentration was 1.63 +/- 0.74 h (range 1-4 h). The plasma LNG concentration versus time profiles were subjected to noncompartmental pharmacokinetic analysis for the purposes of determining half-lives, apparent oral clearances (Cl/F), apparent volumes of distribution after oral administration (V/F), and mean residence time (MRT). Half-lives calculated from the terminal decline in plasma LNG concentrations ranged from 16.2 h to 32.3 h (mean = 24.4 +/- 5.3 h). The Cl/F was 7.06 +/- 2.69 L/h, V/F was 260 +/- 129 L, and MRT was 27.8 +/- 5.2 h. LNG was well tolerated; there were no serious adverse events during the study.

  2. Short-range Fundamental forces

    SciTech Connect

    Antoniadis, I; Baessler, Stefan; Buechner, M; Fedorov, General Victor; Hoedl, S.; Lambrecht, A; Nesvizhevsky, V.; Pignol, G; Reynaud, S.; Sobolev, Yu.

    2011-01-01

    We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: (1) spin-independent forces; and (2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments.

  3. Strongly coupled rotational band in 33Mg

    NASA Astrophysics Data System (ADS)

    Richard, A. L.; Crawford, H. L.; Fallon, P.; Macchiavelli, A. O.; Bader, V. M.; Bazin, D.; Bowry, M.; Campbell, C. M.; Carpenter, M. P.; Clark, R. M.; Cromaz, M.; Gade, A.; Ideguchi, E.; Iwasaki, H.; Jones, M. D.; Langer, C.; Lee, I. Y.; Loelius, C.; Lunderberg, E.; Morse, C.; Rissanen, J.; Salathe, M.; Smalley, D.; Stroberg, S. R.; Weisshaar, D.; Whitmore, K.; Wiens, A.; Williams, S. J.; Wimmer, K.; Yamamato, T.

    2017-07-01

    The "island of inversion" at N ≈20 for the neon, sodium, and magnesium isotopes has long been an area of interest both experimentally and theoretically due to the subtle competition between 0p-0h and n p -n h configurations leading to deformed shapes. However, the presence of rotational band structures, which are fingerprints of deformed shapes, have only recently been observed in this region. In this work, we report on a measurement of the low-lying level structure of 33Mg populated by a two-stage projectile fragmentation reaction and studied with the Gamma Ray Energy Tracking In-Beam Nuclear Array (GRETINA). The experimental level energies, ground-state magnetic moment, intrinsic quadrupole moment, and γ -ray intensities show good agreement with the strong-coupling limit of a rotational model.

  4. Half-life determination for 27Mg

    NASA Astrophysics Data System (ADS)

    Zahn, G. S.; Genezini, F. A.

    2015-07-01

    In this work, the half-life of the short-lived magnesium radionuclide 27Mg was measured by following the activity of samples after they were irradiated in the IEA-R1 reactor. An exponential decay function was then fitted to the results using the counts from a 60Co source as livetime chronometer; the individual half-life values obtained for each irradiation were compiled using both the usual unweighted and σ-2-weighted averages, as well as the robust averages obtained using the Normalized Residuals and the Rajeval techniques. The final halflive values obtained aren't compatible with the ENSDF compilation values, but have a similar uncertainty; analysis of the experimental literature values, all from the 50’s-60’s, show that further measurements should be undertaken in order to achieve a more robust consensus value for this half-life.

  5. Global Investigation of the Mg Atom and ion Layers using SCIAMACHY/Envisat Observations between 70 km and 150 km Altitude and WACCM-MG Model Results

    NASA Technical Reports Server (NTRS)

    Langowski, M.; vonSavigny, C.; Burrows, J. P.; Feng, W.; Plane, J. M. C.; Marsh, D. R.; Janches, Diego; Sinnhuber, M.; Aikin, A. C.

    2014-01-01

    Mg and Mg+ concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg+ dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly means of Mg and Mg+ for number density as well as vertical column density in different latitudinal regions are shown. Data from the limb mesosphere-thermosphere mode of SCIAMACHY/Envisat are used, which covers the 50 km to 150 km altitude region with a vertical sampling of 3.3 km and a highest latitude of 82 deg. The high latitudes are not covered in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm(exp-3) and 2000 cm(exp-3). Mg does not show strong seasonal variation at mid-latitudes. The Mg+ peak occurs 5-15 km above the neutral Mg peak at 95-105 km. Furthermore, the ions show a significant seasonal cycle with a summer maximum in both hemispheres at mid- and high-latitudes. The strongest seasonal variations of the ions are observed at mid-latitudes between 20-40 deg and densities at the peak altitude range from 500 cm(exp-3) to 6000 cm(exp-3). The peak altitude of the ions shows a latitudinal dependence with a maximum at mid-latitudes that is up to 10 km higher than the peak altitude at the equator. The SCIAMACHY measurements are compared to other measurements and WACCM model results. In contrast to the SCIAMACHY results, the WACCM results show a strong seasonal variability for Mg with a winter maximum, which is not observable by SCIAMACHY, and globally higher peak densities. Although the peak densities do not agree the vertical column densities agree, since SCIAMACHY results show a wider vertical profile. The agreement of SCIAMACHY and WACCM results is much better for Mg+, showing the same seasonality and similar peak densities. However

  6. Thermoluminescence of K-Mg-Al-Zn fluorophosphate glass

    NASA Astrophysics Data System (ADS)

    Thomas, Sunil; Chithambo, M. L.

    2017-02-01

    The thermoluminescence of beta irradiated K-Mg-Al-Zn fluorophosphate glass is reported. A glow-curve corresponding to 10 Gy measured at 1 °C/s shows two peaks, a weaker-intensity one at 70 °C and a more prominent one at 235 °C, the subject of this report. The main peak was observed to fade with delay between irradiation and measurement and specifically, by 11% in 15 h. Its dose response is superlinear in the dose range 1-190 Gy although the change was linear for the initial 10 Gy. Regarding kinetic analysis, the activation energy of the higher temperature peak was evaluated as 1.31 eV and that of the lower temperature peak was found as 0.47 eV. It was also noted that the main peak is affected by thermal quenching with an activation energy for thermal quenching equal to 1.37 eV. It is proposed that the mechanism associated with the thermoluminescence in K-Mg-Al-Zn fluorophosphate glass is that electrons trapped by the metal cations are released during heating and then recombine with holes at oxygen sites.

  7. Novel Co:MgF2 lidar for aerosol profiler

    NASA Technical Reports Server (NTRS)

    Acharekar, M. A.

    1993-01-01

    Lidars are of great interest because of their unique capabilities in remote sensing applications in sounding of the atmosphere, meteorology, and climatology. In this small business innovative research (SBIR) phase II program, laser sources including Co:MgF2, CTH:YAG, CTH:YSGG, CT:YAG, and Er:Glass were evaluated. Modulator of fused silica and TeO2 materials with Brewster's angle end faces were used with these lasers as acousto-optical (AO) Q-switches. A higher hold-off energy and hence a higher Q-switched energy was obtained by using a high power RF driver. The report provides performance characteristics of these lasers. The tunable (1.75-2.50 microns) Co:MgF2 laser damaged the TeO2 Q-switch cell. However, the CTH:YAG laser operating at 2.09 microns provided output energy of over 300 mJ/p in 50 ns pulse width using the fused silica Q-switch. This Q-switched CTH:YAG laser was used in a breadboard vertical aerosol profiler. A 40 cm diameter telescope, InSb and InGaAs detectors were used in the receiver. The data obtained using this lidar is provided in the report. The data shows that the eye safe lidar using CTH:YAG laser for the vertical aerosol density and range measurements is the viable approach.

  8. Exosome Proteome of U-87MG Glioblastoma Cells

    PubMed Central

    Chun, Sohyun; Ahn, Seunghyun; Yeom, Chang-Hwan; Park, Seyeon

    2016-01-01

    Exosomes are small membrane vesicles between 30 and 100 nm in diameter secreted by many cell types, and are associated with a wide range of physiological and/or pathological processes. Exosomes containing proteins, lipids, mRNA, and microRNA contribute to cell-to-cell communication and cell-to-environment regulation, however, their biological functions are not yet fully understood. In this report, exosomes in the glioblastoma cell line, U-87MG, were isolated and the proteome was investigated. In addition, exosome proteome changes in U-87MG cells exposed to a low temperature were investigated to elucidate whether the exosome proteome could respond to an external stimulus. Cell culture medium was collected, and exosomes were isolated by continuous centrifugation eliminating cell debris, nucleic acids, and other particles. The morphology of exosomes was observed by cryo-tunneling electron microscopy. According to 2-dimensional electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry, certain proteins including collagen type VI alpha 1, putative RNA-binding protein 15B chain A, substrate induced remodeling of the active site regulates HTRA1, coatomer protein complex-subunit beta 2, myosin-heavy chain 1, and keratin-type I cytoskeletal 9 showed differences between the control proteome and the low temperature-exposed proteome. PMID:27929413

  9. Preparation of Mg-MgH2 flakes by planetary ball milling with stearic acid and their hydrogen storage properties

    NASA Astrophysics Data System (ADS)

    Hong, Seong-Hyeon; Song, Myoung Youp

    2016-05-01

    Many studies preparing magnesium hydride using catalyst addition were performed, resulting in the preparation of additive-containing magnesium hydride. Preparation of a sample with a MgH2 phase without additives requires high pressure and high temperature and is time-demanding. In order to prepare an additive-free sample with a MgH2 phase, 90 wt% Mg+10 wt% MgH2 (named 90Mg+10MgH2) was milled under a hydrogen atmosphere with 6 wt% stearic acid as a process-controlling agent, which led to a formation of Mg-MgH2 flakes. The hydrogen storing and releasing properties of the prepared flakes were investigated and compared with those of purchased MgH2. A sample with a majority fraction of MgH2 phase was prepared by planetary ball milling of 90 Mg+10 MgH2 with 6 wt% stearic acid. The resultant particles of 90 Mg+10 MgH2 obtained after hydridingdehydriding cycling were much smaller and had significantly more cracks and defects than those of MgH2 after hydriding-dehydriding cycling. 90 Mg+10 MgH2 released 0.12 wt% hydrogen for 4 min, 3.70 wt% for 20 min, and 5.30 wt% for 60 min at 648 K at the first cycle.

  10. Effect of organic ligands on Mg partitioning and Mg isotope fractionation during low-temperature precipitation of calcite in the absence of growth rate effects

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; Immenhauser, Adrian; Buhl, Dieter; Purgstaller, Bettina; Baldermann, Andre; Dietzel, Martin

    2017-06-01

    Calcite growth rate has been previously shown to be the dominating parameter controlling both Mg partitioning and Mg isotope fractionation during calcite growth. In natural calcite precipitation environments - characterized by abundant organic material - the presence of dissolved organic molecules may affect these two parameters. In order to assess the role of organic molecules, steady state calcite growth experiments have been performed at 25 °C, 1 bar pCO2 and constant, within analytical uncertainty growth rate (rp = 10-7.4 mol m-2 s-1) in the presence of aqueous Mg and six organic ligands in the concentration range from 0.01 to 10 mM. The organic ligands used in this study are: (i) acetic acid, (ii) citric acid, (iii) glutamic acid, (iv) salycilic acid, (v) glycine, and (vi) ethylenediaminetetraacetic acid (EDTA). These contain one or more carboxyl- and amino-groups that are commonly present in natural organic substances found in lacustrine, fluvial, soil, cave, as well as in marine and earliest diagenetic porewater environments. Results shown here indicate that the presence of these carboxyl- and amino-groups promotes an increase in the partition coefficient of Mg in calcite (DMg = (Mg/Ca)calcite/(Mg/Ca)fluid) that can be attributed to their adsorption onto the calcite surfaces and the subsequent reduction of the active sites of growth. This increase of DMg values as a function of the supersaturation degree of calcite in the fluid phase can be described by the linear equation:

  11. Ranging Behaviour of Commercial Free-Range Laying Hens

    PubMed Central

    Chielo, Leonard Ikenna; Pike, Tom; Cooper, Jonathan

    2016-01-01

    Simple Summary Commercial free-range production has become a significant sector of the fresh egg market due to legislation banning conventional cages and consumer preference for products perceived as welfare friendly, as access to outdoor range can lead to welfare benefits such as greater freedom of movement and enhanced behavioural opportunities. This study investigated dispersal patterns, feather condition and activity of laying hens in three distinct zones of the range area; the apron area near shed; enriched zone 10–50 m from shed; and outer range beyond 50 m, in six flocks of laying hens under commercial free-range conditions varying in size between 4000 and 24,000 hens. Each flock was visited for four days to record number of hens in each zone, their behaviour, feather condition and nearest neighbour distances (NND), as well as record temperature and relative humidity during the visit. Temperature and relative humidity varied across the study period in line with seasonal variations and influenced the use of range with fewer hens out of shed as temperature fell or relative humidity rose. On average, 12.5% of the hens were observed on the range and most of these hens were recorded in the apron zone as hen density decreased rapidly with increasing distance from the shed. Larger flocks appeared to have a lower proportion of hens on range. The hens used the range more in the early morning followed by a progressive decrease through to early afternoon. The NND was greatest in the outer range and decreased towards the shed. Feather condition was generally good and hens observed in the outer range had the best overall feather condition. Standing, pecking, walking and foraging were the most commonly recorded behaviours and of these, standing occurred most in the apron whereas walking and foraging behaviours were recorded most in the outer range. This study supported the findings of previous studies that reported few hens in the range and greater use of areas closer

  12. The Portevin-Le Chatelier effect in an Al-Mg alloy

    NASA Astrophysics Data System (ADS)

    Mogucheva, Anna; Saenko, Mikhail; Kaibyshev, Rustam

    2016-11-01

    The Portevin-Le Chatelier (PLC) effect has been studied in an Al-Mg alloy. A series off tensile tests was carried out at temperatures ranging from -100 to 150°C at plastic strain rates ranging from a low 10-1 s-1 to a high of 10-5 s-1. The coarse-grained material displays tensile curves typical of Al-Mg alloys with an extensive initial strain hardening and an overall parabolic shape until necking. Mixed type (A + B) serrations take place during the strain hardening stage.

  13. A Master Switch Couples Mg2+-Assisted Catalysis to Domain Motion in B. stearothermophilus Tryptophanyl-tRNA Synthetase

    PubMed Central

    Weinreb, Violetta; Li, Li; Carter, Charles W.

    2011-01-01

    Summary We demonstrate how Tryptophanyl-tRNA synthetase (TrpRS) uses conformation-dependent Mg2+ activation to couple catalysis of tryptophan activation to specific, functional domain movements. Rate acceleration by Mg2+ requires ~ -6.0 kcal/mole in protein•Mg2+ interaction energy, none of which arises from the active site. A highly cooperative interaction between Mg2+ and four residues from a remote, conserved motif that mediates the shear of domain movement: (i) destabilizes the pre-transition state conformation, thereby (ii) inducing the Mg2+ to stabilize the transition state for kcat by ~ -5.0 kcal/mole. Cooperative, long-range conformational effects on the metal therefore convert an inactive Mg2+ coordination into one that can stabilize the transition state if, and only if, domain motion occurs. Transient, conformation-dependent Mg2+ activation, analogous to the escapement in mechanical clocks, explains vectorial coupling. PMID:22244762

  14. Atomic structure of amorphous Mg40Cu35Ti25 alloy: An ab initio molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Durandurdu, Murat

    2013-01-01

    Ab initio molecular dynamics simulations are carried out to model amorphous Mg40Cu35Ti25 and its local structural packing are investigated using a variety of analyzing techniques. Cu-atoms commonly form 12 fold coordinated clusters and some of which are perfect or defective types icosahedrons, implying an icosohedral short range order around Cu atoms. Mg and Ti atoms, on the other hand, favor to structure in higher coordinated polyhedrons. The coordination number of Ti atoms is slightly less than Mg atoms. The immiscibility effect between Ti and Mg is reflected by a low fraction of Mg-Ti bonding in the model. The atomic packing of Mg40Cu35Ti25 appears to be noticeably different from that of Mg-Cu-X (X=Y and Gd) metallic glasses even though all these materials exhibit primarily the same type of bonding natures.

  15. Internal reduction of (Mg,Ni)O: Morphology and kinetics

    SciTech Connect

    Rogers, K.A.; Trumble, K.P.

    1996-12-31

    Internal reduction microstructures in the (Mg{sub 1{minus}x}Ni{sub x})O system were studied as a function of temperature from 800 to 1350 {degrees}C and composition from 0.10 {le} x {le} 0.75. The microstructural variety extends from very fine Ni particles to a large scale interpenetrating vermiculite structures. Reduction microstructures are discussed in terms of composition and reduction temperature as a function of homologous temperature. The reduction kinetics in same composition range were studied, resulting in reduction rates an order of magnitude faster that observed previously with single crystals. The reduction rate was found to decrease with increasing composition, counter to most of the experimental evidence to date.

  16. Structural and collisional data for Mg III and Al IV

    NASA Astrophysics Data System (ADS)

    Elabidi, Haykel

    2014-10-01

    We present in this work energy levels, oscillator strengths, radiative decay rates and fine structure collision strengths for the Mg III and Al IV ions. The 11 configurations: (1s2) 2s22p6, 2s22p53l, 2s2p63l, 2s22p54l (l⩽n-1, where n is the principal quantum number), yielding the lowest 75 levels are used. The collisional data for these two ions are missing in the literature, especially the database CHIANTI, this is the principal motivation behind the present work. Calculations have been performed using the AUTOSTRUCTURE code. AUTOSTRUCTURE treats the scattering problem in the distorted wave approach. Fine structure collision strengths are calculated for a range of electron energies from 10 Ry to 240 Ry. The atomic structure data are compared to available experimental and theoretical results.

  17. Electrical properties and initial permeability of Cu-Mg ferrites

    NASA Astrophysics Data System (ADS)

    Ateia, E.; Ahmed, M. A.; Ghouniem, R. M.

    2014-05-01

    A series of polycrystalline spinel ferrites with composition Cu1-xMgxFe2O4 where 0.0 ≤ x ≤ 1 are prepared by the standard ceramic method. The single-phase cubic spinel structure of all the samples has been confirmed from X-ray diffraction analysis. The lattice constant increases linearly with increasing magnesium content obeying Vegard's law. The electrical properties (ɛ‧, and σ) of the prepared samples are measured at different temperatures as a function of applied frequency ranging from 100 kHz up to 5 MHz. The general trend of ɛ‧, and σ is decreased with increasing Mg2+ and increases with increasing temperature. The observed variation of dielectric properties is explained on the basis of Cu2+/Cu1+ ionic concentration as well as the electronic hopping frequency between Fe2+ and Fe3+ ions in the present samples. The data of initial permeability is also discussed.

  18. Study of α cluster structure in 22Mg

    NASA Astrophysics Data System (ADS)

    Cha, S. M.; Chae, K. Y.; Abe, K.; Bae, S. H.; Choi, S. H.; Binh, D. N.; Duy, N. N.; Hahn, K. I.; Hayakawa, S.; Hong, B.; Jung, H. S.; Kahl, D.; Khiem, L. H.; Kim, A.; Kim, D. H.; Kim, E. J.; Kim, G. W.; Kim, M. J.; Kwag, K. J.; Kwag, M. S.; Kwon, Y. K.; Lee, C. S.; Lee, E. J.; Lim, S. I.; Moon, B.; Moon, J. Y.; Nakao, T.; Park, S. Y.; Shimizu, H.; Yamaguchi, H.; Yang, L.; Zhuang, G.

    2017-09-01

    The α -cluster structure in the nuclei has been investigated for the perspective of nuclear structure. Contrary to the case of the 4 N nuclei with N = Z , the experimental evidences of the clustering structures for the proton-rich systems are still lacking information. In order to study the interesting proton-rich ^{22} Mg radionuclide, the ^{18} Ne( α , α ^{18} Ne elastic scattering will be measured at the Center for Nuclear Study Radioactive Ion Beam Separator of the University of Tokyo. By comparing the experimentally-obtained excitation function with theoretical R -matrix calculations, the resonance parameters of the ^{18} Ne+ α system will be provided in the energy range ˜1 { MeV} < E_{c.m.} < 12.4 { MeV}.

  19. Thermoluminescence studies of γ-irradiated ZnO:Mg2+ nanoparticles

    NASA Astrophysics Data System (ADS)

    Pushpa, N.; Kokila, M. K.; Nagabhushana, K. R.

    2016-07-01

    Pure and Mg2+ doped ZnO nanoparticles are synthesized by solution combustion method. X-ray diffraction studies of the samples confirm hexagonal phase. Crystallite size is calculated using Scherer formula and found to be ∼30 nm for undoped ZnO and 34-38 nm for Mg2+ doped ZnO. A broad PL emission in the range 400-600 nm with peaks at 400, 450, 468, 483, 492, 517, 553 nm are observed in both pure and Mg2+ doped nanoparticles. Near band edge emission of ZnO is observed at 400 nm. The broad band emissions are due to surface defects. PL emission intensity is found to increase with Mg2+ concentration up to 1.5 mol% and then decreases due to concentration quenching. Samples are irradiated with γ-rays in a dose range 0.05-8 kGy. Gamma irradiation doesn't affect PL properties. Undoped samples exhibit unstructured low intense TL glow with peak at 720 K. Whereas Mg2+ doped samples exhibit well structured TL glow curves with peak at ∼618 K. TL glow peak intensity of Mg2+ doped samples increases with Mg2+ concentration up to 2 mol%, thereafter decreases. TL curves of Mg2+ (2 mol%) doped ZnO exhibit two glows, a high intense peak at 618 K and a weak one with peak at ∼485 K. TL intensity of Mg2+ (2 mol%) doped ZnO samples increases with gamma dose up to 1 kGy and then decreases. Kinetic parameters of TL glows are calculated by deconvolution technique. Activation energy and frequency factor are found to be 1.5 eV and 3.38 × 1011 s-1 respectively.

  20. Structural and electronic properties of wurtzite MgZnO and BeMgZnO alloys and their thermodynamic stability

    NASA Astrophysics Data System (ADS)

    Gorczyca, I.; Teisseyre, H.; Suski, T.; Christensen, N. E.; Svane, A.

    2016-12-01

    Structural and electronic properties of MgZnO and BeMgZnO alloys are studied by the ab-initio Density Functional Theory method. Large band gap bowings are found for both kinds of alloys. The total energies as functions of the lattice constants are calculated and used to determine the ranges of composition in which the alloys are stable in the wurtzite structure. It is shown that the addition of 6% of Be can already help in stabilization of the MgZnO alloy in the wurtzite structure. The band gap can reach 7 eV for the wurtzite BexMg0.5Zn0.5-xO alloys with x approaching 0.5 and about 5.0 eV for Be0.125MgxZn0.875-xO type alloys for x approaching 0.6. Varying the alloy composition according to the presented stabilization diagram showing ranges of the x, y, for which BexMgyZn1-x-yO is stable in the wurtzite phase, one may tune band gaps over a wide spectral range, which provides flexibility in band gap engineering.

  1. Porous composite materials ZrO2(MgO)-MgO for osteoimplantology

    NASA Astrophysics Data System (ADS)

    Buyakov, Ales; Litvinova, Larisa; Shupletsova, Valeria; Kulbakin, Denis; Kulkov, Sergey

    2016-08-01

    The pore structure and phase composition of ceramic composite material ZrO2(Mg)-MgO at different sintering temperatures were studied. The main mechanical characteristics of the material were determined and it was shown that they are close to the characteristics of natural bone tissues. It was shown that material structure has a positive effect on the pre-osteoblast cells proliferation. In-vitro studies of pre-osteoblast cells, cultivation on material surface showed a good cell adhesion, proliferation and differentiation of MMSC by osteogenic type.

  2. Porous composite materials ZrO{sub 2}(MgO)-MgO for osteoimplantology

    SciTech Connect

    Buyakov, Ales; Litvinova, Larisa Shupletsova, Valeria; Kulbakin, Denis; Kulkov, Sergey

    2016-08-02

    The pore structure and phase composition of ceramic composite material ZrO{sub 2}(Mg)-MgO at different sintering temperatures were studied. The main mechanical characteristics of the material were determined and it was shown that they are close to the characteristics of natural bone tissues. It was shown that material structure has a positive effect on the pre-osteoblast cells proliferation. In-vitro studies of pre-osteoblast cells, cultivation on material surface showed a good cell adhesion, proliferation and differentiation of MMSC by osteogenic type.

  3. Properties of magnetic tunnel junctions with a MgO/CoFeB/Ta/CoFeB/MgO recording structure down to junction diameter of 11 nm

    NASA Astrophysics Data System (ADS)

    Sato, H.; Enobio, E. C. I.; Yamanouchi, M.; Ikeda, S.; Fukami, S.; Kanai, S.; Matsukura, F.; Ohno, H.

    2014-08-01

    We investigate properties of perpendicular anisotropy magnetic tunnel junctions (MTJs) with a recording structure of MgO/CoFeB/Ta/CoFeB/MgO down to junction diameter (D) of 11 nm from 56 nm. Thermal stability factor (Δ) of MTJ with the structure starts to decrease at D = 30 nm. D dependence of Δ agrees well with that expected from magnetic properties of blanket film taking into account the change in demagnetizing factors of MTJs. Intrinsic critical current (IC0) reduces with decrease of D in the entire investigated D range. A ratio of Δ to IC0 shows continuous increase with decrease of D down to 11 nm.

  4. Isotopic mass fractionation laws for magnesium and their effects on 26Al-26Mg systematics in solar system materials

    NASA Astrophysics Data System (ADS)

    Davis, Andrew M.; Richter, Frank M.; Mendybaev, Ruslan A.; Janney, Philip E.; Wadhwa, Meenakshi; McKeegan, Kevin D.

    2015-06-01

    Magnesium isotope ratios are known to vary in solar system objects due to the effects of 26Al decay to 26Mg and mass-dependent fractionation, but anomalies of nucleosynthetic origin must also be considered. In order to infer the amount of enhancement of 26Mg/24Mg due to 26Al decay or to resolve small nucleogenetic anomalies, the exact relationship between 26Mg/24Mg and 25Mg/24Mg ratios due to mass-dependent fractionation, the mass-fractionation "law", must be accurately known so that the 25Mg/24Mg ratio can be used to correct the 26Mg/24Mg ratio for mass fractionation. Mass-dependent fractionation in mass spectrometers is reasonably well characterized, but not necessarily fully understood. It follows a simple power fractionation law, sometimes referred to as the "exponential law". In contrast, mass fractionation in nature, in particular that due to high temperature evaporation that likely caused the relatively large effects observed in calcium-, aluminum-rich inclusions (CAIs), is reasonably well understood, but mass-fractionation laws for magnesium have not been explored in detail. The magnesium isotopic compositions of CAI-like evaporation residues produced in a vacuum furnace indicate that the slope on a log 25Mg/24Mg vs. log 26Mg/24Mg plot is ∼0.5128, and different from those predicted by any of the commonly used mass-fractionation laws. Evaporation experiments on forsterite-rich bulk compositions give exactly the same slope, indicating that the measured mass-fractionation law for evaporation of magnesium is applicable to a wide range of bulk compositions. We discuss mass-fractionation laws and the implications of the measured fractionation behavior of magnesium isotopes for 26Al-26Mg chronology.

  5. Inter-species and Seasonal Variability in Mg / Ca in Larger Benthic Foraminifera: Implications for Paleo-proxy

    NASA Astrophysics Data System (ADS)

    Singh, A.; Saraswati, P. K.; Pande, K.; Sanyal, P.

    2015-12-01

    The reports of inter-species variability to intra-test heterogeneity in Mg/Ca in several species of foraminifera have raised question about its use in estimation of seawater temperatures and necessitate field and culture studies to verify it for species from different habitats. In this study, we attempt to investigate if Mg/Ca in larger benthic foraminifera (LBF) could be a potential proxy of seawater temperatures for shallow marine carbonates. The samples were collected in different seasons from coral reef at Akajima (Okinawa, Japan). The Ca and Mg of 13 species of LBF and small benthic foraminifera from the same season were determined to examine variation in Mg/Ca among the species calcified under presumably the same temperature and salinity conditions. We also analyzed Amphistegina lessoni from different seasons for Ca, Mg and δ18O to determine variation in Mg/Ca with temperature and see how the two proxies of temperatures, Mg/Ca and δ18O, correlate in the same species. The species cluster about two distinctly separated Mg/Ca values. The first group comprising species of Amphistegina, Gypsina, Ammonia and Elphidium have relatively lower Mg/Ca, varying from 30 to 45 mmol/mol. The second group, having average Mg/Ca ranging from ~110 to 170 mmol/mol, includes species of Schlumbergerella, Baculogypsinoides, Baculogypsina, Heterostegina, Operculina, Calcarina, Amphisorus, Alveolinella and Poroeponides. The result suggests large interspecies variability implying vital effect in foraminiferal Mg/Ca. There is no distinct difference in Mg/Ca values between porcelaneous and hyaline types or symbiont-bearing and symbiont-free types. In Amphistegina lessoni the variation in Mg/Ca between individuals of the same season is as large as variation across the seasons. There is no correlation between Mg/Ca and seawater temperature. Lack of correlation between Mg/Ca and δ18O further suggests that Mg/Ca in the species is not primarily controlled by temperature.

  6. Quantifying the Potential Influence of Carbonate Saturation State on Benthic Foraminiferal Mg/Ca

    NASA Astrophysics Data System (ADS)

    Martin, P. A.; Lea, D. W.; McCorkle, D. C.

    2002-05-01

    Benthic foraminiferal Mg/Ca paleothermometry is based on an empirical relationship between the Mg/Ca of benthic foraminifera recovered from core tops and in situ bottom water temperatures (Rosenthal, 1997; Martin et al, in press; Lear et al, in review). While there is a tight correlation between shell Mg/Ca and temperature over a broad range of temperatures (-1 to 20 degrees C), Mg/Ca variation over the small range of deep water temperatures reveals departures from the calibration curve at low temperatures. Lower Mg/Ca values are generally associated with the deepest sites from the Atlantic and Pacific, contributing to an apparently steeper Mg/Ca-T response for abyssal benthics. The steeper response of abyssal benthics may reflect an influence of decreasing carbonate saturation with depth. Dissolution or other saturation related effects have already been documented for Mg in planktonic foraminifera and for other metals (Cd, Ba, and Zn) in benthic foraminifera shells (see Marchitto and ref. therein). Although it is difficult to definitively separate the effects of various environmental parameters (including temperature, depth, and relative saturation states), which often change in unison, we can use to the core top Mg/Ca data to estimate the potential influence of saturation state. An alternative calibration of the benthic Mg/Ca - T relationship can be derived based on core top benthic foraminifera only from sites bathed in waters above carbonate saturation, which yields a slightly smaller change in Mg/Ca per degree C (~9.5% vs. 11%) but better explains benthic Mg/Ca from the coldest sites (-1oC). Using this alternative Mg/Ca -T relation and a subset of the data from the Ceara Rise and Ontong Java Plateau, we can estimate a maximum Mg/Ca offset attributable to saturation state. The uncertainty this implies for downcore reconstructions varies widely (exceeding 1.5oC), depending on the hydrographic setting and which proxy is used to estimate saturation state.

  7. Extended range chemical sensing apparatus

    DOEpatents

    Hughes, Robert C.; Schubert, W. Kent

    1994-01-01

    An apparatus for sensing chemicals over extended range of concentrations. In particular, first and second sensors each having separate, but overlapping ranges for sensing concentrations of hydrogen are provided. Preferably, the first sensor is a MOS solid state device wherein the metal electrode or gate is a nickel alloy. The second sensor is a chemiresistor comprising a nickel alloy.

  8. Extended range chemical sensing apparatus

    DOEpatents

    Hughes, R.C.; Schubert, W.K.

    1994-01-18

    An apparatus is described for sensing chemicals over extended range of concentrations. In particular, first and second sensors each having separate, but overlapping ranges for sensing concentrations of hydrogen are provided. Preferably, the first sensor is a MOS solid state device wherein the metal electrode or gate is a nickel alloy. The second sensor is a chemiresistor comprising a nickel alloy. 6 figures.

  9. Desert Experimental Range: Annotated bibliography

    Treesearch

    E. Durant McArthur; Stanley G. Kitchen

    2013-01-01

    Entries qualify for inclusion if they were conducted in whole or part at the Desert Experimental Range (DER, also known as the Desert Range Experiment Station) or were based on DER research in whole or part. They do not qualify merely by the author having worked at the DER when the research was performed or prepared. Entries were drawn from the original abstracts or...

  10. Role of dopants in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P detectors

    SciTech Connect

    Mohammadi, Kh. Moussavi Zarandi, A.; Afarideh, H.; Shahmaleki, S.

    2013-06-15

    In this study, electronic structure of LiF crystal doped with Mg,Cu,P impurities was studied with WIEN2k code on the basis of FPLAPW+lo method. Results show that in Mg-doped LiF composition, an electronic trap was created with impurity concentration of 1.56% and 3.125%. In this condition, the electronic trap with increasing the percentage of the impurities up to 4.687% is annihilated. It was found, that by doping of Mg and Cu or P simultaneously, a hole-trap is created in valence band. It was realized that in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P, Cu impurity and Li atom, have a key role in creation of levels which lead to create electronic and hole traps. Mg impurity and F atom, only have a role in creation of electronic traps. In addition, P impurity has a main role in creation of the electronic and hole traps in LiF:Mg,Cu,P. The activation energy of electronic and hole trap in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P crystalline lattice were obtained as 0.3 and 5.5 eV, 0.92 and 3.4 eV and 0.75 and 3.1 eV, respectively. - Graphical abstract: Figure (a) and (b) shows changes in electronic structure and band gap energy of LiF crystal due to presence of Mg and Cu, Mg and P ions respectively. - Highlights: • Electronic structure of LiF, LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P materials were studied with WIEN2K code. • In LiF:Mg,Cu and LiF:Mg,Cu,P, Li atom and Cu impurity have a key role in creation of levels. • F atom and Mg impurity only have a role in creation of electronic traps. • In LiF:Mg,Cu,P, P impurity has a main role in creation of electronic and hole traps.

  11. High dynamic range subjective testing

    NASA Astrophysics Data System (ADS)

    Allan, Brahim; Nilsson, Mike

    2016-09-01

    This paper describes of a set of subjective tests that the authors have carried out to assess the end user perception of video encoded with High Dynamic Range technology when viewed in a typical home environment. Viewers scored individual single clips of content, presented in High Definition (HD) and Ultra High Definition (UHD), in Standard Dynamic Range (SDR), and in High Dynamic Range (HDR) using both the Perceptual Quantizer (PQ) and Hybrid Log Gamma (HLG) transfer characteristics, and presented in SDR as the backwards compatible rendering of the HLG representation. The quality of SDR HD was improved by approximately equal amounts by either increasing the dynamic range or increasing the resolution to UHD. A further smaller increase in quality was observed in the Mean Opinion Scores of the viewers by increasing both the dynamic range and the resolution, but this was not quite statistically significant.

  12. Phase transition and optoelectronic properties of MgH2

    NASA Astrophysics Data System (ADS)

    Nayak, Vikas; Verma, U. P.

    2016-05-01

    In this article, structural and electronic properties of MgH2 have been studied. The aim behind this study was to find out the ground state crystal structure of MgH2. For the purpose, density functional theory (DFT)-based full-potential linearized augmented plane wave (FP-LAPW) calculations have been performed in three different space groups: P42/mnm (α-MgH2), Pa3 (β-MgH2) and Pbcn (γ-MgH2). It has been found that the ground state structure of MgH2 is α-MgH2. The present study shows that α-MgH2 transforms into γ-MgH2 at a pressure of 0.41 GPa. After further increase in pressure, γ-MgH2 transforms into β-MgH2 at a pressure of 3.67 GPa. The obtained results are in good agreement with previously reported experimental data. In all the studied phases, the behavior of MgH2 is insulating and its optical conductivity is around 6.0 eV. The α-MgH2 and γ-MgH2 are anisotropic materials while β-MgH2 is isotropic in nature.

  13. [Magnesium (Mg) status in patients with cardiovascular diseases].

    PubMed

    Sasaki, S; Oshima, T; Teragawa, H; Matsuura, H; Kajiyama, G; Kambe, M

    1999-05-01

    Mg is the fourth most abundant total cation in the human body and the second most abundant intracellular cation. Moreover, Mg is an important cofactor for many enzymes especially those involved in phosphate transfer reactions. Mg is therefore essential in the regulation of the metabolism of other ions and cellular functions. Mg deficiency has been shown to be associated with fatal cardiovascular diseases such as cardiac arrhythmias and coronary heart disease, as well as with risk factors for these diseases, such as hypertension, and diabetes mellitus. Clinical evaluation of Mg status has been limited by the lack of suitable technology for measuring this cation. Although the measurement of serum total Mg is routinely available, ionized Mg is physiologically active. Furthermore, most of the body's Mg is present in the intracellular space. Our findings showed that serum total Mg was similar in all groups, but patients with arrhythmias and diabetes mellitus revealed lower levels of serum ionized Mg. On the other hand, patients with essential hypertension exhibited higher intraerythrocyte Mg concentrations than healthy controls. The measurement of serum total Mg may obscure the diagnosis of an abnormality in Mg metabolism in patients with arrhythmias and diabetes mellitus. Furthermore, the intracellular accumulation of Mg does not support the hypothesis of Mg deficiency in patients with essential hypertension.

  14. The effects of serpentinization on Mg isotopes in Mid-Atlantic ridge peridotite

    NASA Astrophysics Data System (ADS)

    Wimpenny, J.; Harvey, J.; Yin, Q.

    2012-12-01

    The magnesium isotope composition of the Earth's mantle [1], and bulk estimates for upper crustal rocks [2] overlap with values obtained from chondritic meteorites [1], suggesting broad scale homogeneity of δ26Mg on Earth. By way of contrast, weathering of continental crust results in significant fractionation of Mg isotopes [3]. Negative δ26Mg in riverine and groundwater fluxes suggest that the lighter isotopes of Mg are preferentially removed in fluid during partial weathering, leaving a heavy δ26Mg residuum [4]. Thus, riverine fluxes to the ocean result in a marine reservoir with a δ26Mg = -0.82 ± 0.01 [5], significantly lighter than that of fresh mantle material and its derivatives [1]. Abyssal peridotites recovered from Ocean Drilling Program Leg 209 display a wide range of bulk-rock compositions and have been demonstrated to have interacted with a number of low and high temperature fluids [6]. Peridotite from Hole 1274a has been variably serpentinized at low (c. 200 oC) temperatures. Serpentinized samples from Hole 1268a, have also interacted with a higher temperature fluid (c. 350 oC) with a low Mg/Si ratio resulting in abundant talc formation [6]. Serpentinites contain high concentrations of Mg and are abundantly exposed at the seafloor at slow and ultra-slow oceanic ridges [7,8]. Because peridotites are thought to be a source of Mg to seawater [9] any fractionation of Mg isotopes that accompanies serpentinization will have implications for the composition of Mg in seawater. The δ26Mg of samples from 1274a are similar to primary upper crustal rocks, (UCC δ26Mg = -0.22 ± 0.04 [2]). However, samples from 1268a have fractionated δ26Mg values that are generally enriched in isotopically heavy Mg relative to the UCC, ranging from -0.25 to -0.02‰. These results suggest that serpentinization itself does not cause fractionation of Mg, but that later formation of talc is associated with the preferential retention of isotopically heavy Mg, consistent with

  15. Foraging optimally for home ranges

    USGS Publications Warehouse

    Mitchell, Michael S.; Powell, Roger A.

    2012-01-01

    Economic models predict behavior of animals based on the presumption that natural selection has shaped behaviors important to an animal's fitness to maximize benefits over costs. Economic analyses have shown that territories of animals are structured by trade-offs between benefits gained from resources and costs of defending them. Intuitively, home ranges should be similarly structured, but trade-offs are difficult to assess because there are no costs of defense, thus economic models of home-range behavior are rare. We present economic models that predict how home ranges can be efficient with respect to spatially distributed resources, discounted for travel costs, under 2 strategies of optimization, resource maximization and area minimization. We show how constraints such as competitors can influence structure of homes ranges through resource depression, ultimately structuring density of animals within a population and their distribution on a landscape. We present simulations based on these models to show how they can be generally predictive of home-range behavior and the mechanisms that structure the spatial distribution of animals. We also show how contiguous home ranges estimated statistically from location data can be misleading for animals that optimize home ranges on landscapes with patchily distributed resources. We conclude with a summary of how we applied our models to nonterritorial black bears (Ursus americanus) living in the mountains of North Carolina, where we found their home ranges were best predicted by an area-minimization strategy constrained by intraspecific competition within a social hierarchy. Economic models can provide strong inference about home-range behavior and the resources that structure home ranges by offering falsifiable, a priori hypotheses that can be tested with field observations.

  16. Range indices of geomagnetic activity

    USGS Publications Warehouse

    Stuart, W.F.; Green, A.W.

    1988-01-01

    The simplest index of geomagnetic activity is the range in nT from maximum to minimum value of the field in a given time interval. The hourly range R was recommended by IAGA for use at observatories at latitudes greater than 65??, but was superceded by AE. The most used geomagnetic index K is based on the range of activity in a 3 h interval corrected for the regular daily variation. In order to take advantage of real time data processing, now available at many observatories, it is proposed to introduce a 1 h range index and also a 3 h range index. Both will be computed hourly, i.e. each will have a series of 24 per day, the 3 h values overlapping. The new data will be available as the range (R) of activity in nT and also as a logarithmic index (I) of the range. The exponent relating index to range in nT is based closely on the scale used for computing K values. The new ranges and range indices are available, from June 1987, to users in real time and can be accessed by telephone connection or computer network. Their first year of production is regarded as a trial period during which their value to the scientific and commercial communities will be assessed, together with their potential as indicators of regional and global disturbances' and in which trials will be conducted into ways of eliminating excessive bias at quiet times due to the rate of change of the daily variation field. ?? 1988.

  17. The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

    PubMed Central

    Mueller, Wolf-Dieter; Hornberger, Helga

    2014-01-01

    Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE) is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys. PMID:24972140

  18. Enhancement of lower critical field in thin MgB2 films and MgB2/MgO multilayers

    NASA Astrophysics Data System (ADS)

    Tan, Teng; Johnson, Evan; Acharya, Narendra; Hambe, Michael; Chen, Ke; Krick, Alex; May, Steven; Xi, Xiaoxing

    2013-03-01

    Magnesium diboride is a conventional superconductor with a high Tc of 39 K, a low residual resistivity of < 0.1 μΩ cm (at 42 K), and higher thermodynamic critical field Hc values than Nb. These properties make MgB2 a promising superconductor as an alternative to Nb for future SRF cavities. However, the lower critical field Hc 1 of MgB2 is low, and vortex dissipation above Hc 1 can lead to degradation of the quality factor and low RF breakdown field. Here, we report an enhancement of Hc 1 in thin MgB2 films and MgB2/MgO multilayers. The value of Hc 1(5K) is increased from 40 mT in a 300 nm-thick MgB2 film to 180 mT when the MgB2 layer thickness is 100 nm either in a single-layer film or in a MgB2/MgO multilayer with a total MgB2 layer thickness of 300 nm. Superconducting MgB2 thin films have been coated in-situon the inner wall of a SRF cavity using the hybrid physical chemical vapor deposition (HPCVD) technique. The characterization of the coating will be presented.

  19. How Wide Does the Wide Range Achievement Test Really Range?

    ERIC Educational Resources Information Center

    McBeath, Marcia; Marken, Dan

    Local norms for the three scores of the Wide Range Achievement Test (WRAT)--reading, spelling, and arithmetic--were developed on the basis of 1,021 children in the age range of 5 through 7 and 83 more children aged 8 through 11 from a suburban school district near Seattle, Washington. In general, the local group was found to be superior to the…

  20. Home range analysis using a mechanistic home range model

    SciTech Connect

    Moorcroft, P.R. . Dept. of Ecology and Evolutionary Biology); Lewis, M.A. . Dept. of Mathematics) Crabtree, R.L. . Dept. of Fish and Wildlife Resources)

    1999-07-01

    The traditional models used to characterize animal home ranges have no mechanistic basis underlying their descriptions of space use, and as a result, the analysis of animal home ranges has primarily been a descriptive endeavor. In this paper, the authors characterize coyote (Canis latrans) home range patterns using partial differential equations for expected space use that are formally derived from underlying descriptions of individual movement behavior. To the authors' knowledge, this is the first time that mechanistic models have been used to characterize animal home ranges. The results provide empirical support for a model formulation of movement response to scent marks, and suggest that having relocation data for individuals in adjacent groups is necessary to capture the spatial arrangement of home range boundaries. The authors then show how the model fits can be used to obtain predictions for individual movement and scent marking behavior and to predict changes in home range patterns. More generally, the findings illustrate how mechanistic models permit the development of a predictive theory for the relationship between movement behavior and animal spatial distribution.

  1. Mycoplasma genitalium mg200 and mg386 genes are involved in gliding motility but not in cytadherence.

    PubMed

    Pich, Oscar Q; Burgos, Raul; Ferrer-Navarro, Mario; Querol, Enrique; Piñol, Jaume

    2006-06-01

    Isolation and characterization of transposon-generated Mycoplasma genitalium gliding-deficient mutants has implicated mg200 and mg386 genes in gliding motility. The proposed role of these genes was confirmed by restoration of the gliding phenotype in deficient mutants through gene complementation with their respective mg386 or mg200 wild-type copies. mg200 and mg386 are the first reported gliding-associated mycoplasma genes not directly involved in cytadherence. Orthologues of MG200 and MG386 proteins are also found in the slow gliding mycoplasmas, Mycoplasma pneumoniae and Mycoplasma gallisepticum, suggesting the existence of a unique set of proteins involved in slow gliding motility. MG200 and MG386 proteins share common features, such as the presence of enriched in aromatic and glycine residues boxes and an acidic and proline-rich domain, suggesting that these motifs could play a significant role in gliding motility.

  2. Semiconducting p-type MgNiO:Li epitaxial films fabricated by cosputtering method

    SciTech Connect

    Kwon, Yong Hun; Chun, Sung Hyun; Cho, Hyung Koun

    2013-07-15

    Li-doped ternary Mg{sub x}Ni{sub 1-x}O thin films were deposited on (0001) Al{sub 2}O{sub 3} substrates by a radio frequency (RF) magnetron cosputtering method with MgO and NiO:Li targets. The Mg mole fraction and Li content were relatively controlled by changing RF power for the MgO target over a range of 0-300 W, while the NiO:Li target was kept at 150 W. As a result, all films were epitaxially grown on (0001) Al{sub 2}O{sub 3} substrates with the relationship of [110]{sub NiO}||[1110]{sub Al2O3}, [112]{sub NiO}||[2110]{sub Al2O3} (in-plane), and [111]{sub NiO}||[0001]{sub Al2O3} (out-of-plane), and showed p-type semiconducting properties. Furthermore, from x-ray diffraction patterns, the authors found that MgO was effectively mixed with NiO:Li without structural deformation due to low lattice mismatch (0.8%) between NiO and MgO. However, the excess Li contents degraded the crystallinity of the MgNiO films. The band-gap of films was continuously shifted from 3.66 eV (339 nm) to 4.15 eV (299 nm) by the RF power of the MgO target. A visible transmittance of more than 80% was exhibited at RF powers higher than 200 W. Ultimately, the electrical resistivity of p-type MgNiO films was improved from 7.5 to 673.5 {Omega}cm, indicating that the Li-doped MgNiO films are good candidates for transparent p-type semiconductors.

  3. Cisplatinum enhancement of myocardial Mg2+ transport.

    PubMed

    Murphy, L; Procopio, J M; Bianchi, C P

    1996-01-01

    Cisplatinum in a concentration (4.3 x 10(-6) M) corresponding to the therapeutic plasma concentration for cancer patients was found to cause a marked enhancement of magnesium efflux and uptake in perfused frog myocardium. The magnesium content of the perfused frog ventricle is increased from 6.66 +/- 0.34 mumol/g wet wgt to 8.03 +/- 0.38 mu mol/g wet wgt. Cisplatinum had a negative inotropic action reducing contractile force to 46 +/- 8% of initial force after 40 min of perfusion. The corresponding control contractile force was reduced to 74 +/- 7%. Removal of calcium and magnesium from the perfusion solution containing 0.5 mM EDTA for 10 minutes caused contractile force to be reduced to 0 after 6 beats at 24 min-1. After ten minutes of perfusion with EDTA, 1.87 mu mol/g wet wgt of magnesium was lost from control ventricles. Cisplatinum increased the loss to 4.08 +/- 0.34 mu mol/g wet wgt. The magnesium lost during EDTA perfusion was completely recovered after 5 minutes of perfusion in Ringer or Tyrode solution by both control and cisplatinum treated frog ventricles. The contractile force also recovered to the level prior to perfusion with EDTA Ringer. The rate of Mg2+ efflux in EDTA Ringer is largest during the first 3 minutes and was 0.170 +/- 0.051 p mol cm-2 sec-1 for controls and 0.798 p mol cm-2 sec-1 for the cisplatinum treated ventricles. During the last 7 min of perfusion in EDTA Ringer the Mg2+ efflux was reduced to 0.057 +/- 0.005 p mol cm-2 sec-1 for control ventricles and 0.170 p mol cm-2 sec-1 for the cisplatinum treated ventricles. Cisplatinum increased both magnesium efflux and influx and influx in the frog myocardium, increased magnesium content to a higher level and reduced contractile force. The effect of cisplatinum on magnesium transport is attributed to an increase in the charged form of cisplatinum that accumulates inside the cell where chloride content is low and the chloride of cisplatinum is displaced to form a positively charged

  4. First-principles studies of hydrogen interaction with ultrathin Mg and Mg-based alloy films

    NASA Astrophysics Data System (ADS)

    Yoon, Mina; Weitering, Hanno H.; Zhang, Zhenyu

    2011-01-01

    The search for technologically and economically viable storage solutions for hydrogen fuel would benefit greatly from research strategies that involve systematic property tuning of potential storage materials via atomic-level modification. Here, we use first-principles density-functional theory to investigate theoretically the structural and electronic properties of ultrathin Mg films and Mg-based alloy films and their interaction with atomic hydrogen. Additional delocalized charges are distributed over the Mg films upon alloying them with 11.1% of Al or Na atoms. These extra charges contribute to enhance the hydrogen binding strength to the films. We calculated the chemical potential of hydrogen in Mg films for different dopant species and film thickness, and we included the vibrational degrees of freedom. By comparing the chemical potential with that of free hydrogen gas at finite temperature (T) and pressure (P), we construct a hydrogenation phase diagram and identify the conditions for hydrogen absorption or desorption. The formation enthalpies of metal hydrides are greatly increased in thin films, and in stark contrast to its bulk phase, the hydride state can only be stabilized at high P and T (where the chemical potential of free H2 is very high). Metal doping increases the thermodynamic stabilities of the hydride films and thus significantly helps to reduce the required pressure condition for hydrogen absorption from H2 gas. In particular, with Na alloying, hydrogen can be absorbed and/or desorbed at experimentally accessible T and P conditions.

  5. ZnO/(ZnMg)O single quantum wells with high Mg content graded barriers

    SciTech Connect

    Laumer, Bernhard; Schuster, Fabian; Wassner, Thomas A.; Stutzmann, Martin; Rohnke, Marcus; Schoermann, Joerg; Eickhoff, Martin

    2012-06-01

    ZnO/Zn{sub 1-x}Mg{sub x}O single quantum wells (SQWs) were grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. Compositional grading allows the application of optimized growth conditions for the fabrication of Zn{sub 1-x}Mg{sub x}O barriers with high crystalline quality and a maximum Mg content of x = 0.23. High resolution x-ray diffraction reveals partial relaxation of the graded barriers. Due to exciton localization, the SQW emission is found to consist of contributions from donor-bound and free excitons. While for narrow SQWs with well width d{sub W}{<=}2.5nm, the observed increase of the exciton binding energy is caused by quantum confinement, the drop of the photoluminescence emission below the ZnO bulk value found for wide SQWs is attributed to the quantum-confined Stark effect. For a Mg content of x = 0.23, a built-in electric field of 630 kV/cm is extracted, giving rise to a decrease of the exciton binding energy and rapid thermal quenching of the SQW emission characterized by an activation energy of (24 {+-} 4) meV for d{sub W} = 8.3 nm.

  6. Mechanical and Corrosive Properties of Two Magnesium Wires: Mg4Gd and Mg6Ag

    NASA Astrophysics Data System (ADS)

    Maier, Petra; Szakács, Gabor; Wala, Marcin; Hort, Norbert

    The mechanical and corrosive properties of two Magnesium wires are studied in the field of microhardness, tension-, compression-and 3-point-bending tests, corrosion and its influence on the mechanical properties. Due to recrystallization during their complex forming processes (casting, extrusion, wire drawing), both wires show a fine grained microstructure resulting in high strength and ductility. However, the ductility is mostly evaluated by 3-point bending and compression; due to the notch effect in the clamp area, the maximum tensile strength and elongation under tension cannot be measured. Both alloys show a tensile-compressive yield asymmetry. Even RE-elements are known to reduce this asymmetry, the Mg-Gd alloy shows 100 MPa higher strength in tension than compression. The asymmetry of the Mg-Ag wire is similar. Overall the wires show very high strength and hardness, Mg6Ag slightly higher compared to Mg4Gd. Strong pitting corrosion is found and reduces strongly the tensile and bending strength.

  7. Photo-induced reactions in the ion-molecule complex Mg+-OCNC2H5

    NASA Astrophysics Data System (ADS)

    Sun, Ju-Long; Liu, Haichuan; Han, Ke-Li; Yang, Shihe

    2003-06-01

    Ion-molecule complexes of magnesium cation with ethyl isocyanate were produced in a laser-ablation supersonic expansion nozzle source. Photo-induced reactions in the 1:1 complexes have been studied in the spectral range of 230-410 nm. Photodissociation mass spectrometry revealed the persistent product Mg+ from nonreactive quenching throughout the entire wavelength range. As for the reactive channels, the photoproducts, Mg+OCN and C2H5+, were produced only in the blue absorption band of the complex with low yields. The action spectrum of Mg+(OCNC2H5) consists of two pronounced peaks on the red and blue sides of the Mg+ 32P←32S atomic transition. The ground state geometry of Mg+-OCNC2H5 was fully optimized at B3LYP/6-31+G** level by using GAUSSIAN 98 package. The calculated absorption spectrum of the complex using the optimized structure of its ground state agrees well with the observed action spectrum. Photofragment branching fractions of the products are almost independent of the photolysis photon energy for the 3Px,y,z excitations. The very low branching ratio of reactive products to nonreactive fragment suggests that evaporation is the main relaxation pathway in the photo-induced reactions of Mg+(OCNC2H5).

  8. High pressure phase equilibrium in the system Fe-Mg-Si-O

    SciTech Connect

    Saxena, S.K.; Fei, Y.

    1985-01-01

    Recent experimental data on high pressure synthesis of minerals in the Fe-Mg-Si-O system permit the establishment of a thermochemical-thermophysical data set with which phase equilibrium for the earth's mantle can be computed. The results indicate that low pressure (<200 Kbar) silicates (Mg-Fe) spinel and stishovite react to form (Mg-Fe) perovskite and (Mg-Fe) wuestite starting at a pressure close to 200 Kbar. The iron content of perovskite increases with depth a corresponding iron depletion in wuestite. Between 1000 and 1100 Kbar, both minerals begin to lose iron rapidly with pressure. Metal Fe with almost pure Mg-perovskite, MgO and oxygen becomes stable above 1200 Kbar, which pressure corresponds closely to the core-mantle boundary. This is a general feature over a range of temperatures and compositions. Conclusions are a) the present state of the earth is a consequence of thermochemical equilibrium which could have established over a range of post-accretionary temperatures, and b) the oxygen released in the equilibrium reaction could be available as a light element in the core. These results have a very important influence on trace element geochemical models of the mantle and therefore, on models of petrogenetic evolution of the earth.

  9. Structural and optoelectronic properties of Mg substituted ZTe (Z=Zn, Cd and Hg)

    NASA Astrophysics Data System (ADS)

    Khan, Imad; Subhan, Fazle; Ahmad, Iftikhar; Ali, Zahid

    2015-08-01

    Wide band gap semiconductor alloys, MgxZ1-xTe (Z=Zn, Cd and Hg), are investigated over a full range of Mg compositions (0≤x≤1) using density functional theory (DFT). The variation in the lattice constant of MgxZ1-xTe is linear with the composition x, and all these alloys obey Vegrd's law. The CdTe (6.50 Å) and MgTe (6.44 Å) are lattice matched compounds, therefore the lattice constant of MgCdTe decreases slightly with the concentration x, whereas the lattice constant also decreases for MgHgTe but increases for MgZnTe. It is due to the fact that Mg has larger size than Zn and smaller size than Cd and Hg. The band gap of these compounds are calculated using the modified Becke-Johnson (mBJ) exchange potential as LDA and GGA are not effective in producing the experimental band gap of a strongly correlated electron system. The calculated band gaps of these compounds cover the range 0-3.5 eV and are consistent with the experimental band gaps. The band gaps exhibit nonlinear behavior or bowing effect with the change in concentration. The frequency dependent optical properties like dielectric functions, and indices of refraction of these ternary systems are also calculated and discussed.

  10. Streak camera dynamic range optimization

    SciTech Connect

    Wiedwald, J.D.; Lerche, R.A.

    1987-09-01

    The LLNL optical streak camera is used by the Laser Fusion Program in a wide range of applications. Many of these applications require a large recorded dynamic range. Recent work has focused on maximizing the dynamic range of the streak camera recording system. For our streak cameras, image intensifier saturation limits the upper end of the dynamic range. We have developed procedures to set the image intensifier gain such that the system dynamic range is maximized. Specifically, the gain is set such that a single streak tube photoelectron is recorded with an exposure of about five times the recording system noise. This ensures detection of single photoelectrons, while not consuming intensifier or recording system dynamic range through excessive intensifier gain. The optimum intensifier gain has been determined for two types of film and for a lens-coupled CCD camera. We have determined that by recording the streak camera image with a CCD camera, the system is shot-noise limited up to the onset of image intensifier nonlinearity. When recording on film, the film determines the noise at high exposure levels. There is discussion of the effects of slit width and image intensifier saturation on dynamic range. 8 refs.

  11. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

    PubMed Central

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-01-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes—conversion and deposition coatings—while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches

  12. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants.

    PubMed

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-10-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes-conversion and deposition coatings-while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches are

  13. Analgesic efficacy and tolerability of oxycodone 5 mg/ibuprofen 400 mg compared with those of oxycodone 5 mg/acetaminophen 325 mg and hydrocodone 7.5 mg/acetaminophen 500 mg in patients with moderate to severe postoperative pain: a randomized, double-blind, placebo-controlled, single-dose, parallel-group study in a dental pain model.

    PubMed

    Litkowski, Leonard J; Christensen, Steven E; Adamson, Dennis N; Van Dyke, Thomas; Han, Seung-Ho; Newman, Kenneth B

    2005-04-01

    Combination therapy has been widely used for the clinical management of acute pain. By combining 2 drugs with different mechanisms of action, such therapy provides additive analgesic effects while reducing the risk for adverse effects. This study compared the efficacy and tolerability of oxycodone 5 mg/ibuprofen 400 mg with those of oxycodone 5 mg/acetaminophen 325 mg, hydrocodone 7.5 mg/acetaminophen 500 mg, and placebo in a dental pain model. This was a multicenter, randomized, double-blind, placebo- and active-controlled, parallel-group, single-dose study in patients experiencing moderate to severe pain after surgical removal of > or = 2 ipsilateral impacted third molars. Patients were randomly assigned to receive oxycodone 5 mg/ibuprofen 400 mg, oxycodone 5 mg/acetaminophen 325 mg, hydrocodone 7.5 mg/acetaminophen 500 mg, or placebo. The primary outcome measures were total pain relief through 6 hours after dosing (TOTPAR6), sum of pain intensity differences through 6 hours (SPID6), and adverse events. Secondary efficacy measures included SPID3 and TOTPAR3, peak pain relief, peak pain intensity difference, time to onset of pain relief, time to use of rescue medication, proportion of patients reporting pain half gone, and the patient's global evaluation. Two hundred forty-nine patients (43.5% male; 87.5% white; mean age, 19.1 years; mean body weight, 153.6 pounds) were randomized to treatment as follows: 62 to oxycodone 5 mg/ibuprofen 400 mg, 61 to oxycodone 5 mg/acetaminophen 325 mg, 63 to hydrocodone 7.5 mg/acetaminophen 500 mg, and 63 to placebo. Oxycodone 5 mg/ibuprofen 400 mg provided significantly greater analgesia compared with oxycodone 5 mg/acetaminophen 325 mg, hydrocodone 7.5 mg/acetaminophen 500 mg, and placebo (mean [SD] TOTPAR6, 14.98 [5.37], 9.53 [6.77], 8.36 [6.68], and 5.05 [6.49], respectively; P < 0.001, oxycodone 5 mg/ibuprofen 400 mg vs all other treatments). SPID6 values also differed significantly for oxycodone 5 mg/ibuprofen 400 mg

  14. GPS test range mission planning

    NASA Astrophysics Data System (ADS)

    Roberts, Iris P.; Hancock, Thomas P.

    The principal features of the Test Range User Mission Planner (TRUMP), a PC-resident tool designed to aid in deploying and utilizing GPS-based test range assets, are reviewed. TRUMP features time history plots of time-space-position information (TSPI); performance based on a dynamic GPS/inertial system simulation; time history plots of TSPI data link connectivity; digital terrain elevation data maps with user-defined cultural features; and two-dimensional coverage plots of ground-based test range assets. Some functions to be added during the next development phase are discussed.

  15. Rotational band structure in 32Mg

    NASA Astrophysics Data System (ADS)

    Crawford, H. L.; Fallon, P.; Macchiavelli, A. O.; Poves, A.; Bader, V. M.; Bazin, D.; Bowry, M.; Campbell, C. M.; Carpenter, M. P.; Clark, R. M.; Cromaz, M.; Gade, A.; Ideguchi, E.; Iwasaki, H.; Langer, C.; Lee, I. Y.; Loelius, C.; Lunderberg, E.; Morse, C.; Richard, A. L.; Rissanen, J.; Smalley, D.; Stroberg, S. R.; Weisshaar, D.; Whitmore, K.; Wiens, A.; Williams, S. J.; Wimmer, K.; Yamamato, T.

    2016-03-01

    There is significant evidence supporting the existence of deformed ground states within the neutron-rich N ≈20 neon, sodium, and magnesium isotopes that make up what is commonly called the "island of inversion." However, the rotational band structures, which are a characteristic fingerprint of a rigid nonspherical shape, have yet to be observed. In this work, we report on a measurement and analysis of the yrast (lowest lying) rotational band in 32Mg up to spin I =6+ produced in a two-step projectile fragmentation reaction and observed using the state-of-the-art γ -ray tracking detector array, GRETINA (γ -ray energy tracking in-beam nuclear array). Large-scale shell-model calculations using the SDPF-U-MIX effective interaction show excellent agreement with the new data. Moreover, a theoretical analysis of the spectrum of rotational states as a function of the pairing gap, together with cranked-shell-model calculations, provides intriguing evidence for a reduction in pairing correlations with increased angular momentum, also in line with the shell-model results.

  16. Rotational Band Structure in 32Mg

    NASA Astrophysics Data System (ADS)

    Crawford, Heather; NSCL E11029 Collaboration Team

    2016-03-01

    There is significant evidence supporting the existence of deformed ground states within the neutron-rich N =20 neon, sodium, and magnesium isotopes that make up what is commonly called the ``Island of Inversion''. However, rotational band structures, a characteristic fingerprint of a rigid non-spherical shape, have yet to be observed. We report on a measurement and analysis of the yrast (lowest lying) rotational band in 32Mg up to spin I = 6+, produced in a two-step projectile fragmentation reaction and observed using the state-of-the-art γ-ray tracking detector array, GRETINA. Large-scale shell model calculations using the SDPF-U-MIX effective interaction show excellent agreement with the new data. Moreover, a theoretical analysis of the spectrum of rotational states as a function of the pairing gap, together with cranked shell model calculations, provides intriguing evidence for a reduction in pairing correlations with increased angular momentum, also in line with the shell-model results. This material is based upon work supported by the U.S. DOE, Office of Science, NP Office under Contract No. DE-AC02-05CH11231 (LBNL). GRETINA was funded by the U.S. DOE Office of Science. Operation of the array at NSCL was supported by NSF.

  17. Microstructural formation in a hypereutectic Mg-Si alloy

    SciTech Connect

    Pan Yichuan . E-mail: riverpan@mail.sdu.edu.cn; Liu Xiangfa; Yang Hua

    2005-09-15

    In the present work, the microstructure of an ingot metallurgy hypereutectic Mg-8 wt.% Si alloy was studied using electron probe microanalysis (EPMA) and the solidification process was discussed. The components of the alloy are Mg{sub 2}Si and Mg. The solidified microstructure of the alloy contains three constituents: Mg{sub 2}Si primary dendrites that are surrounded by Mg sub-primary particles and the Mg-Mg{sub 2}Si eutectic. The primary Mg{sub 2}Si dendrites have a secondary dendrite arm spacing d {sub 2} of approximately 17 {mu}m or show polygonal morphologies with a mean size of 30 {mu}m. An Mg phase appearing as halos surround the Mg{sub 2}Si constituents. The Mg-Mg{sub 2}Si eutectic has a regular morphology of rod-like Mg{sub 2}Si distributed in a continuous matrix of Mg having an interphase spacing r of approximately 0.8 {mu}m.

  18. Autocatalytic Surface Hydroxylation of MgO(100) Terrace Sites Observed Under Ambient Conditions

    SciTech Connect

    Newberg, J.T.; Starr, D.; Yamamoto, S.; Kaya, S.; Kendelewicz, T.; Mysak E.R.; Porsgaard, S.; Salmeron, M.B.; Brown, Jr., G.E.; Nilsson, A.; Bluhm, H.

    2011-06-01

    We have investigated the reaction of water vapor with the MgO(100) surface using ambient pressure X-ray photoelectron spectroscopy (AP-XPS), which permits the study of the chemical composition of the MgO/water vapor interface at p(H{sub 2}O) in the Torr range. Water dissociation on thin MgO(100) films of 4-5.5 monolayers (ML) grown on Ag(100) was studied under isobaric conditions at p(H{sub 2}O) ranging from 0.005 to 0.5 Torr and temperatures from 380 to -10 C, up to a maximum relative humidity (RH) of 20%. At RH < 0.01% dissociative adsorption occurs only at defect sites (0.08 ML), while terrace sites remain unreactive toward water dissociation. In the range 0.01 < RH < 0.1% there is an abrupt onset of dissociative adsorption at terrace sites which saturates at 1 ML at 0.1% RH, and is accompanied by an increase in molecular water adsorption. At 20% RH there is 1 ML of molecularly adsorbed water interacting with a fully hydroxylated interface on MgO(100). The observed onset of hydroxylation near 0.01% RH is suggested to be due to water molecules aggregating at the surface, leading to an autocatalytic dissociation of water at MgO(100) terrace sites.

  19. A placebo-controlled study of three agomelatine dose regimens (10 mg, 25 mg, 25-50 mg) in patients with major depressive disorder.

    PubMed

    Kennedy, Sidney H; Avedisova, Alla; Giménez-Montesinos, Natalia; Belaïdi, Carole; de Bodinat, Christian

    2014-04-01

    A randomised placebo-controlled "dose relation study" was conducted in 549 patients who met the criteria for major depressive disorder, to evaluate the efficacy and safety of three doses regimens of agomelatine during 6 weeks: low fixed dosage (10 mg/day, n=133), fixed dosage (25 mg/day, n=138) and a flexible dosage with up-titration in case of insufficient improvement at week 2 (25-50 mg/day, n=137). At last post-baseline assessment, there were significant and incremental placebo-agomelatine differences on mean HAM-D₁₇ total scores in favour of each agomelatine dose regimen (2.46 ± 0.76 points, p=0.001 at 10 mg; 4.71+0.75 points, p<0.0001 at 25 mg and 4.92 ± 0.76 points, p<0.0001 at 25-50 mg) with statistically significant differences between 25 mg and 25-50 mg dose regimens compared to the 10 mg dose. The response rate according to HAM-D₁₇ was significantly higher in patients taking agomelatine than those taking placebo (difference of 16.1% at 10 mg p=0.005; 25.9% and 27.4% respectively at 25 mg and 25-50 mg, p<0.0001). The benefit of agomelatine was demonstrated in the subgroup of severely depressed patients in the 25 mg and 25-50 mg/day regimens. Consistent clinical response according to CGI variables and better social functioning were found in patients receiving agomelatine. All dose regimens of agomelatine were well tolerated and no unexpected adverse event was reported. This study provides evidence of a dose effect for agomelatine between 10 mg and the therapeutic dose regimen of agomelatine 25-50 mg: the efficacy of the higher dose regimens being more efficacious than the lowest (10 mg) daily dose. The data support a definitive statement regarding the utility of 25 mg as the threshold dose for initiating agomelatine in depressed patients. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

  20. Thermal Parameters and Microstructural Development in Directionally Solidified Zn-Rich Zn-Mg Alloys

    NASA Astrophysics Data System (ADS)

    Vida, Talita A.; Freitas, Emmanuelle S.; Brito, Crystopher; Cheung, Noé; Arenas, Maria A.; Conde, Ana; De Damborenea, Juan; Garcia, Amauri

    2016-06-01

    Transient directional solidification experiments have been carried out with Zn-Mg hypoeutectic alloys under an extensive range of cooling rates with a view to analyzing the evolution of microstructure. It is shown that the microstructure is formed by a Zn-rich matrix of different morphologies and competitive eutectic mixtures (Zn-Zn11Mg2 and Zn-Zn2Mg). For 0.3 wt-pct Mg and 0.5 wt-pct Mg alloys, the Zn-rich matrix is shown to be characterized by high-cooling rates plate-like cells (cooling rates >9.5 and 24 K/s, respectively), followed by a granular-dendritic morphological transition for lower cooling rates. In contrast, a directionally solidified Zn1.2 wt-pct Mg alloy casting is shown to have the Zn-rich matrix formed only by dendritic equiaxed grains. Experimental growth laws are proposed relating the plate-like cellular interphase, the secondary dendritic arm spacing, and the eutectic interphase spacings to solidification thermal parameters, i.e., cooling rate and growth rate. The experimental law for the growth of secondary dendritic spacings under unsteady-state solidifications is also shown to encompass results of hypoeutectic Zn-Mg alloys subjected to steady-state Bridgman growth.

  1. Oxide solubilities and phase relations in the system Mg-Nd-O-Cl

    SciTech Connect

    Kipouros, G.; Mediaas, H.; Vindstad, J.E.; Oestvold, T.; Tkatcheva, O.

    1996-10-01

    Freezing point depression measurements have been performed for the CaCl{sub 2}-NdOCl, Cs{sub 2}MgCl{sub 4}-NdOCl and MgCl{sub 2}-NdOCl liquid binaries with small additions of NdOCl. Very low NdOCl solubilities are observed in all the three binaries. Calculated solubility products of NdOCl at 1,073 K in CaCl{sub 2} and Cs{sub 2}MgCl{sub 4} are in the range 10{sup {minus}6}--10{sup {minus}8} confirming the experimental data.The MgCl{sub 2}-NdOCl system is more complicated. In the very dilute region NdOCl dissolves by forming two foreign ions probably Mg{sub 2}OCl{sub 5}{sup 3{minus}} and Nd{sup 3+} or NdO{sup +} and Mg{sub n}Cl{sub m}{sup (2n-m)-} depending on which cation Mg{sup 2+} or Nd{sup 3+} will bond the O{sup 2{minus}} ion most strongly.

  2. Magnetism of Amorphous and Nano-Crystallized Dc-Sputter-Deposited MgO Thin Films

    PubMed Central

    Mahadeva, Sreekanth K.; Fan, Jincheng; Biswas, Anis; Sreelatha, K.S.; Belova, Lyubov; Rao, K.V.

    2013-01-01

    We report a systematic study of room-temperature ferromagnetism (RTFM) in pristine MgO thin films in their amorphous and nano-crystalline states. The as deposited dc-sputtered films of pristine MgO on Si substrates using a metallic Mg target in an O2 containing working gas atmosphere of (N2 + O2) are found to be X-ray amorphous. All these films obtained with oxygen partial pressure (PO2) ~10% to 80% while maintaining the same total pressure of the working gas are found to be ferromagnetic at room temperature. The room temperature saturation magnetization (MS) value of 2.68 emu/cm3 obtained for the MgO film deposited in PO2 of 10% increases to 9.62 emu/cm3 for film deposited at PO2 of 40%. However, the MS values decrease steadily for further increase of oxygen partial pressure during deposition. On thermal annealing at temperatures in the range 600 to 800 °C, the films become nanocrystalline and as the crystallite size grows with longer annealing times and higher temperature, MS decreases. Our study clearly points out that it is possible to tailor the magnetic properties of thin films of MgO. The room temperature ferromagnetism in MgO films is attributed to the presence of Mg cation vacancies.

  3. AC conductivity and structural properties of Mg-doped ZnO ceramic

    NASA Astrophysics Data System (ADS)

    Othman, Zayani Jaafar; Hafef, Olfa; Matoussi, Adel; Rossi, Francesca; Salviati, Giancarlo

    2015-11-01

    Undoped ZnO and Zn1- x Mg x O ceramic pellets were synthesized by the standard sintering method at the temperature of 1200 °C. The influence of Mg doping on the morphological, structural and electrical properties was studied. The scanning electron microscopy images revealed rough surface textured by grain boundaries and compacted grains having different shapes and sizes. Indeed, the X-ray diffraction reveals the alloying of hexagonal ZnMgO phase and the segregation of cubic MgO phase. The crystallite size, strain and stress were studied using Williamson-Hall (W-H) method. The results of mean particle size of Zn1- x Mg x O composites showed an inter-correlation with W-H analysis and Sherrer method. The electrical conductivity of the films was measured from 173 to 373 K in the frequency range of 0.1 Hz-1 MHz to identify the dominant conductivity mechanism. The DC conductivity is thermally activated by electron traps having activation energy of about 0.09 to 0.8 eV. The mechanisms of AC conductivity are controlled by the correlated barrier hopping model for the ZnO sample and the small polaron tunneling (SPT) model for Zn0.64Mg0.36O and Zn0.60Mg0.40O composites.

  4. Ostracode Mg/Ca Ratios from Quaternary Sediments of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Dwyer, G. S.; Caverly, E. K.; Cronin, T. M.; Polyak, L. V.; DeNinno, L.; Rodriguez-Lazaro, J.

    2013-12-01

    We analyzed magnesium/calcium (Mg/Ca) ratios from adult, calcitic shells of the deep-sea ostracode Krithe from the Northwind and Mendeleev Ridges, Arctic Ocean, to reconstruct orbital-scale Quaternary bottom-water temperature history. Results show an early Pleistocene (~1.5 Ma to 500 ka) Mg/CaKrithe pattern with low-amplitude, possibly orbitally controlled, oscillations between 10.5 and 12.5 mmol/mol followed by a progressive trend towards higher ratios (> 17 mmol/mol) during the last 500 ka. This shift coincides with the mid-Pleistocene Transition and mid-Brunhes Event (~ 300-500 ka) recognized in microfaunal proxy records in the Arctic Ocean. Analyses of Mg/CaKrithe from intervals representing marine isotope stage 11 (MIS 11) in 5 cores from water depths from 700 to 1470 m show Mg/Ca ratios ranging from 10.5 to 14 mmol/mol. A 2 mmol/mol excursion in Mg/CaKrithe within MIS 11 seen in all cores likely corresponds to a brief stadial event recognized also in planktic and benthic microfaunas. We will discuss the implications of Mg/Ca paleothermometry for deep Arctic Ocean circulation and the evolution of Arctic sea ice during major Quaternary climatic transitions as well as possible factors other than water temperature that may influence Mg/Ca ratios in Krithe shells from Quaternary sediments from the Arctic Ocean.

  5. Pathway and Molecular Mechanisms for Malachite Green Biodegradation in Exiguobacterium sp. MG2

    PubMed Central

    Wang, Ji’ai; Gao, Feng; Liu, Zhongzhong; Qiao, Min; Niu, Xuemei; Zhang, Ke-Qin; Huang, Xiaowei

    2012-01-01

    Malachite green (MG), N-methylated diaminotriphenylmethane, is one of the most common dyes in textile industry and has also been used as an effective antifungal agent. However, due to its negative impact on the environment and carcinogenic effects to mammalian cells, there is a significant interest in developing microbial agents to degrade this type of recalcitrant molecules. Here, an Exiguobacterium sp. MG2 was isolated from a river in Yunnan Province of China as one of the best malachite green degraders. This strain had a high decolorization capability even at the concentration of 2500 mg/l and maintained its stable activity within the pH range from 5.0 to 9.0. High-pressure liquid chromatography, liquid chromatography-mass spectrometry and gas chromatography–mass spectrometry were employed to detect the catabolic pathway of MG. Six intermediate products were identified and a potential biodegradation pathway was proposed. This pathway involves a series of reactions of N-demethylation, reduction, benzene ring-removal, and oxidation, which eventually converted N-methylated diaminotriphenylmethane into N, N-dimethylaniline that is the key precursor to MG. Furthermore, our molecular biology experiments suggested that both triphenylmethane reductase gene tmr and cytochrome P450 participated in MG degradation, consistent with their roles in the proposed pathway. Collectively, our investigation is the first report on a biodegradation pathway of triphenylmethane dye MG in bacteria. PMID:23251629

  6. Comparison between Mg II k and Ca II H images recorded by SUNRISE/SuFI

    SciTech Connect

    Danilovic, S.; Hirzberger, J.; Riethmüller, T. L.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Gizon, L.; Berkefeld, T.; Schmidt, W.; Knölker, M.; Rodríguez, J. Blanco; Iniesta, J. C. Del Toro

    2014-03-20

    We present a comparison of high-resolution images of the solar surface taken in the Mg II k and Ca II H channels of the Filter Imager on the balloon-borne solar observatory SUNRISE. The Mg and Ca lines are sampled with 0.48 nm and 0.11 nm wide filters, respectively. The two channels show remarkable qualitative and quantitative similarities in the quiet Sun, in an active region plage and during a small flare. However, the Mg filtergrams display 1.4-1.7 times higher intensity contrast and appear more smeared and smoothed in the quiet Sun. In addition, the fibrils in a plage are wider. Although the exposure time is 100 times longer for Mg images, the evidence suggests that these differences cannot be explained only with instrumental effects or the evolution of the solar scene. The differences at least partially arise because of different line-formation heights, the stronger response of Mg k emission peaks to the higher temperatures, and the larger height range sampled by the broad Mg filter used here. This is evidently manifested during the flare when a surge in Mg evolves differently than in Ca.

  7. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    NASA Astrophysics Data System (ADS)

    Kumar, Danith; Yadav, L. S. Reddy; Lingaraju, K.; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.; Naika, H. Raja; Chikkahanumantharayappa, Nagaraju, G.

    2015-06-01

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm-1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV -Vis spectrum was found to be in the range 5.40-5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

  8. Two-color Laser Desorption of Nanostructured MgO Thin Films

    SciTech Connect

    Beck, Kenneth M.; Joly, Alan G.; Hess, Wayne P.

    2009-09-30

    Neutral magnesium atom emission from nanostructured MgO thin films is induced using two-color nanosecond laser excitation. We find that combined visible/UV excitation, for single-color pulse energies below the desorption threshold, induces neutral Mg-atom emission with hyperthermal kinetic energies in the range of 0.1- 0.2 eV. The observed metal atom emission is consistent with a mechanism involving rapid electron transfer to 3-coordinated Mg surface sites. The two-color Mg-atom signal is significant only for parallel laser polarizations and temporally overlapped laser pulses indicating that intermediate excited states are short-lived compared to the 5 nanosecond laser pulse duration.

  9. Structure and electromagnetic properties of FeSiAl particles coated by MgO

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhou, Ting-dong

    2017-03-01

    FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)2 sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5-18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to -33 dB.

  10. Mg doped InN and confirmation of free holes in InN

    SciTech Connect

    Wang, K.; Yamaguchi, T.; Miller, N.; Mayer, M. A.; Haller, E. E.; Iwamoto, R.; Araki, T.; Nanishi, Y.; Yu, K. M.; Walukiewicz, W.; Ager, J. W. III

    2011-01-24

    We report a systematic investigation on Mg doped InN epilayers grown by radio-frequency plasma-assisted molecular beam epitaxy. Electrolyte capacitance voltage (ECV) combined with thermopower measurements find p-type conduction over an Mg concentration range. For InN:Mg in this p-type 'window' the Seebeck coefficients dramatically change their signs from negative to positive when the thickness of undoped InN interlayer decreases to zero. This notable sign change of Seebeck coefficient explains the previous inconsistency between ECV and thermopower results and confirms the existence of mobile holes in the InN:Mg. Taking into account the undoped InN interlayer, the hole density and mobility are extracted.

  11. Fabrication and Spark Plasma Sintering of Magnetic alpha-Fe/MgO Nanocomposite by Mechanical Alloying.

    PubMed

    Lee, Chung-Hyo

    2016-02-01

    Solid-state reduction has occurred during mechanical alloying of a mixture of Fe2O3 and Mg powders at room temperature. It is found that magnetic nanocomposite in which MgO is dispersed in alpha-Fe matrix with nano-sized grains is obtained by mechanical alloying of Fe2O3 with Mg for 30 min. Consolidation of the ball-milled powders was performed in a spark plasma sintering (SPS) machine up to 800-1000 degrees C. X-ray diffraction result shows that the average grain size of alpha-Fe in a-Fe/MgO nanocomposite sintered at 800 degrees C is in the range of 110 nm. It can be also seen that the coercivity of SPS sample sintered at 800 degrees C is still high value of 88 Oe, suggesting that the grain growth of magnetic alpha-Fe phase during SPS process tends to be suppressed.

  12. Effect of scandium on the microstructure and ageing behaviour of cast Al-6Mg alloy

    SciTech Connect

    Kaiser, M.S.; Datta, S.; Roychowdhury, A. Banerjee, M.K.

    2008-11-15

    Microstructural modification and grain refinement due to addition of scandium in Al-6Mg alloy has been studied. Transmission electron microscopy is used to understand the microstructure and precipitation behaviour in Al-6Mg alloy doped with scandium. It is seen from the microstructure that the dendrites of the cast Al-6Mg alloy have been refined significantly due to addition of scandium. Increasing amount of scandium leads to a greater dendrite refinement. The age hardening effect in scandium added Al-6Mg alloys has been studied by subjecting the alloys containing varying amount of scandium ranging from 0.2 wt.% to 0.6 wt.% to isochronal and isothermal ageing at various temperatures for different times. It is observed that significant hardening takes place in the aged alloys due to the precipitation of scandium aluminides.

  13. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    SciTech Connect

    Kumar, Danith; Chikkahanumantharayappa; Yadav, L. S. Reddy; Nagaraju, G.; Lingaraju, K.; Naika, H. Raja; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.

    2015-06-24

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm{sup −1} indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

  14. Direct determination of the band alignment at the (Zn,Mg)O/CISSe interface

    SciTech Connect

    Erfurth, F.; Reinert, F.; Weinhardt, L.; Grimm, A.; Palm, J.; Niesen, T. P.; Umbach, E.

    2011-04-04

    The electronic and chemical properties of the (Zn{sub 1-x},Mg{sub x})O/CuIn(S,Se){sub 2} interface, prepared by sputtering of thin (Zn,Mg)O layers, were investigated with direct and inverse photoelectron spectroscopy on in situ prepared samples. With the combination of both techniques we have determined the band alignment at this interface as a function of Mg-content in the range 0{<=}x{<=}0.30. We find that the band alignment at the interface can be tailored between a ''cliff'' (downward step) in the conduction band for pure ZnO and a 'spike' (upward step) for high Mg-contents. A direct influence of the band alignment modifications on the solar cell parameters is found.

  15. Digital laser range finder emulator

    NASA Astrophysics Data System (ADS)

    McDowell, Vaughn P.; Holland, Orgal T.; Wilkerson, Christina G.

    1993-05-01

    A digital laser range finder emulator receives N-bits of range-to-target data in a parallel format and generates N-bits of serial data representative of the range-to-target data and an external synchronization pulse whose presence is indicative of valid serial data. First and second clock pulses are generated such that the second clock pulse is delayed with respect to the first clock pulse. Control logic, responsive to the first clock pulse, generates validity logic while control logic, responsive to the second clock pulse, generates transmit logic. The parallel format range-to-target data is converted into the serial data in response to the first clock pulse. The serial data is then output in response to the transmit logic. A gate, responsive to the second clock pulse and the validity logic, generates the synchronization pulse when the second clock pulse and validity logic occupy a common logic state.

  16. The dynamic range of LZ

    NASA Astrophysics Data System (ADS)

    Yin, J.

    2016-02-01

    The electronics of the LZ experiment, the 7-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to permit studies of physics where the energies deposited range from 1 keV of nuclear-recoil energy up to 3,000 keV of electron-recoil energy. The system is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in multi-tonne time-projection chambers, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined to accommodate the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines.

  17. Genus Ranges of Chord Diagrams

    PubMed Central

    Burns, Jonathan; Jonoska, Nataša; Saito, Masahico

    2015-01-01

    A chord diagram consists of a circle, called the backbone, with line segments, called chords, whose endpoints are attached to distinct points on the circle. The genus of a chord diagram is the genus of the orientable surface obtained by thickening the backbone to an annulus and attaching bands to the inner boundary circle at the ends of each chord. Variations of this construction are considered here, where bands are possibly attached to the outer boundary circle of the annulus. The genus range of a chord diagram is the genus values over all such variations of surfaces thus obtained from a given chord diagram. Genus ranges of chord diagrams for a fixed number of chords are studied. Integer intervals that can be, and those that cannot be, realized as genus ranges are investigated. Computer calculations are presented, and play a key role in discovering and proving the properties of genus ranges. PMID:26478650

  18. Genus Ranges of Chord Diagrams.

    PubMed

    Burns, Jonathan; Jonoska, Nataša; Saito, Masahico

    2015-04-01

    A chord diagram consists of a circle, called the backbone, with line segments, called chords, whose endpoints are attached to distinct points on the circle. The genus of a chord diagram is the genus of the orientable surface obtained by thickening the backbone to an annulus and attaching bands to the inner boundary circle at the ends of each chord. Variations of this construction are considered here, where bands are possibly attached to the outer boundary circle of the annulus. The genus range of a chord diagram is the genus values over all such variations of surfaces thus obtained from a given chord diagram. Genus ranges of chord diagrams for a fixed number of chords are studied. Integer intervals that can be, and those that cannot be, realized as genus ranges are investigated. Computer calculations are presented, and play a key role in discovering and proving the properties of genus ranges.

  19. Airborne 2 color ranging experiment

    NASA Technical Reports Server (NTRS)

    Millar, Pamela S.; Abshire, James B.; Mcgarry, Jan F.; Zagwodzki, Thomas W.; Pacini, Linda K.

    1993-01-01

    Horizontal variations in the atmospheric refractivity are a limiting error source for many precise laser and radio space geodetic techniques. This experiment was designed to directly measure horizontal variations in atmospheric refractivity, for the first time, by using 2 color laser ranging measurements to an aircraft. The 2 color laser system at the Goddard Optical Research Facility (GORF) ranged to a cooperative laser target package on a T-39 aircraft. Circular patterns which extended from the southern edge of the Washington D.C. Beltway to the southern edge of Baltimore, MD were flown counter clockwise around Greenbelt, MD. Successful acquisition, tracking, and ranging for 21 circular paths were achieved on three flights in August 1992, resulting in over 20,000 two color ranging measurements.

  20. The Influence of Grain Boundary Scattering on Thermoelectric Properties of Mg2Si and Mg2Si0.8Sn0.2

    NASA Astrophysics Data System (ADS)

    Pshenai-Severin, D. A.; Fedorov, M. I.; Samunin, A. Yu.

    2013-07-01

    The temperature dependences of the Seebeck coefficient, and electrical and thermal conductivities of bulk hot-pressed Sb-doped n-type Mg2Si and Mg2Si0.8Sn0.2 samples were measured in the temperature range from 300 K to 850 K together with the Hall coefficients at room temperature. The features of the complex band structure and scattering mechanisms were analyzed based on experimental data within the relaxation-time approximation. Based on the obtained model parameters, the possibility of improvement of the thermoelectric figure of merit due to nanostructuring and grain boundary scattering was theoretically analyzed for both Mg2Si and the solid solution.

  1. Structural relationships among MgZn2 and Mg4Zn7 phases and transition structures in Mg-Zn-Y alloys

    NASA Astrophysics Data System (ADS)

    Rosalie, Julian M.; Somekawa, Hidetoshi; Singh, Alok; Mukai, Toshiji

    2010-08-01

    Isothermal ageing of plastically deformed Mg-Zn-Y alloys resulted in precipitation along ? twin boundaries. The bulky precipitates so formed had structures similar to those recently reported for the rod-like ? precipitates, but afforded a more detailed study by high-resolution TEM due to their larger size. The core of the precipitates often had the structure of the monoclinic Mg4Zn7 phase, and had the orientation ? ; ? with either the matrix or the twin. On this Mg4Zn7 phase, the hexagonal MgZn2 phase grew in two orientations, both with ? . One of these orientations formed a known orientation relationship ? ; ? with the matrix. The part of the precipitate with the MgZn2 structure was usually in direct contact with the twin boundary. Both the Mg4Zn7 and MgZn2 phases have layered structures that can be described with similar building blocks of icosahedrally coordinated atoms. The atomic positions of zinc atoms comprise the vertices of these icosahedra and form 'thick' rhombic tiles. The orientations of these rhombuses remain unchanged across the interfaces between the two phases. Near the interface with MgZn2, transition structures formed in the Mg4Zn7 phase, with the Zn:Mg atom ratio between those of the Mg4Zn7 and MgZn2 phases. In these transition structures, the unit cell of the Mg4Zn7 phase is extended along [100] or [001] by half a unit cell length by continuation of the rhombic tiling. Structures of these extended unit cells are proposed.

  2. Starkey experimental forest and range.

    Treesearch

    Valerie. Rapp

    2004-01-01

    The Starkey Experimental Forest and Range. (Starkey) is a one-of-a-kind, world class research facility, located in the Blue Mountains of northeastern Oregon. Starkey is the primary field location for scientific study of the effects of deer, elk, and cattle on ecosystems. Most of the 28,000-acre forest and range is enclosed by a game-proof fence.The research...

  3. Comparative pharmacokinetics and bioavailability of gemifloxacin administered as an intravenous 200 mg formulation or an oral 320 mg tablet.

    PubMed

    Kim, Mi Jo; Lim, Hyeong-Seok; Cho, Sang-Heon; Bae, Kyun-Seop

    2014-03-01

    Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent, which has potent activity against most Gram-negative and Gram-positive organisms. It is indicated for the treatment of community-acquired pneumonia and acute bacterial exacerbation of chronic bronchitis. The aim of this study was to assess the clinical potential of a new gemifloxacin 200 mg intravenous formulation by comparing its pharmacokinetic characteristics with those of the branded Factive(®) gemifloxacin tablet. A single-dose, open-label, randomized-sequence, two-period crossover study was performed with 17 healthy male volunteers. The two treatment periods were separated by a 1-week washout period. Blood samples were taken for up to 48 h post-dose. Plasma gemifloxacin concentrations were determined by a validated high-performance liquid chromatography-tandem mass spectrometry method. To calculate the pharmacokinetic parameters, noncompartmental analysis was performed. The two formulations were considered to be pharmacokinetically equivalent if the 90 % confidence intervals (CIs) of the log-transformed ratios (intravenous/oral formulations) of the area under the plasma concentration-time curve (AUC) from time zero to the time of the last measurable concentration (AUClast) and the AUC from time zero to infinity (AUC∞) were within the standard bioequivalence range (0.8-1.25). Safety and tolerability were evaluated on the basis of physical examinations, vital signs, electrocardiograms, clinical laboratory tests and adverse event monitoring. Seventeen subjects were enrolled, and 15 subjects completed the study. Sixteen subjects received intravenous 200 mg gemifloxacin and 15 received oral 320 mg gemifloxacin. The 15 subjects in the pharmacokinetic analysis set had a mean (standard deviation [SD]) age, height and weight of 27.2 (5.3) years, 173.5 (4.4) cm and 67.3 (7.4) kg, respectively. Both formulations had similar pharmacokinetic profiles. For the intravenous formulation, the mean (SD) AUClast

  4. Elastic and Thermodynamic Properties of Complex Mg-Al Intermetallic Compounds via Orbital-Free Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Zhuang, Houlong; Chen, Mohan; Carter, Emily A.

    2016-06-01

    Magnesium-aluminum (Mg-Al) alloys are important metal alloys with a wide range of engineering applications. We investigate the elastic and thermodynamic properties of Mg, Al, and four stoichiometric Mg-Al compounds including Mg17Al12 , Mg13Al14 , and Mg23Al30 , and MgAl2 with orbital-free density-functional theory (OFDFT). We first calculate the lattice constants, zero-temperature formation energy, and independent elastic constants of these six materials and compare the results to those computed via Kohn-Sham DFT (KSDFT) benchmarks. We obtain excellent agreement between these two methods. Our calculated elastic constants of hexagonal close-packed Mg and face-centered-cubic Al are also consistent with available experimental data. We next compute their phonon spectra using the force constants extracted from the very fast OFDFT calculations, because such calculations are computationally challenging using KSDFT. This is especially the case for the Mg23Al30 compound, whose 3 ×3 ×3 supercell consists of 1431 atoms. We finally employ the quasiharmonic approximation to investigate temperature-dependent thermodynamic properties, including formation energies, heat capacities, and thermal expansion of the four Mg-Al intermetallic compounds. The calculated heat capacity and thermal expansion of both Mg and Al agree well with experimental data. We additionally find that Mg13Al14 and MgAl2 are both unstable, consistent with their absence from the equilibrium Mg-Al phase diagram. Our work demonstrates that OFDFT is an efficient and accurate quantum-mechanical computational tool for predicting elastic and thermodynamic properties of complicated Mg-Al alloys and also should be applicable to many other engineering alloys.

  5. Investigation of Mg isotope fractionation during low temperature precipitation of dolomite analogue minerals BaMg(CO3)2 and PbMg(CO3)2 PbMg(CO3)2

    NASA Astrophysics Data System (ADS)

    Li, W.; Huang, T.; Liu, C.

    2015-12-01

    Stable Mg isotopes are an emerging geochemical tool for studying dolomite-related problems. Currently available Mg isotope fractionation factors for dolomite are calibrated at hydrothermal conditions. Direct measurement of low temperature Mg isotope fractionation between dolomite and aqueous solution is hampered by the difficulty of synthesis of dolomite at ambient abiotic conditions. Dolomite analogue minerals including PbMg(CO3)2 and BaMg(CO3)2, however, can be readily synthesized at low temperatures. Therefore study of fractionation factors of Mg isotopes during PbMg(CO3)2 and BaMg(CO3)2 precipitation at low temperature conditions provides insights on Mg isotope behavior during dolomitization in geological processes.. We successfully synthesized PbMg(CO3)2 and BaMg(CO3)2 at 30-80ºC and characterized the products using scanning electron microscopy (SEM). In general, the crystallinity of PbMg(CO3)2 and BaMg(CO3)2 correlated with temperature. PbMg(CO3)2 synthesized at below 40℃ formed aggregates of nanocrystals. The aggregates became fewer in experiments at higher temperatures, and fine-grained (200~600nm in size), euhedral rhombohedrons of PbMg(CO3)2 were produced in the experiment at 80℃. In BaMg(CO3)2 synthesis experiments, morphology of BaMg(CO3)2 was mainly granular but the crystal size increased from 20 to 100nm with increasing temperature, and 0.5-1.1µm sized euhedral to subhedral crystals were produced at 70 and 80℃. Preliminary Mg isotope analyses for the experimental products show that Δ26Mg fractionation between PbMg(CO3)2 and aqueous solution at 40℃ is -1.87‰, whereas Δ26Mg fractionation between BaMg(CO3)2 and aqueous solution at 40℃ is -1.40‰. The result is consistent with the idea that heavy Mg isotopes favor shorter and stronger Mg-O bonds in minerals.

  6. IMPACT OF A REVISED {sup 25}Mg(p, {gamma}){sup 26}Al REACTION RATE ON THE OPERATION OF THE Mg-Al CYCLE

    SciTech Connect

    Straniero, O.; Cristallo, S.; Imbriani, G.; DiLeva, A.; Limata, B.; Strieder, F.; Bemmerer, D.; Broggini, C.; Caciolli, A.; Corvisiero, P.; Costantini, H.; Lemut, A.; Formicola, A.; Gustavino, C.; Junker, M.; Elekes, Z.; Fueloep, Zs.; Gyuerky, Gy.; Gervino, G.; Guglielmetti, A.; and others

    2013-02-15

    Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar H-burning regions. In particular, low-energy nuclear resonances in the {sup 25}Mg(p, {gamma}){sup 26}Al reaction affect the production of radioactive {sup 26}Al{sup gs} as well as the resulting Mg/Al abundance ratio. Reliable estimations of these quantities require precise measurements of the strengths of low-energy resonances. Based on a new experimental study performed at the Laboratory for Underground Nuclear Astrophysics, we provide revised rates of the {sup 25}Mg(p, {gamma}){sup 26}Al{sup gs} and the {sup 25}Mg(p, {gamma}){sup 26}Al {sup m} reactions with corresponding uncertainties. In the temperature range 50-150 MK, the new recommended rate of {sup 26}Al {sup m} production is up to five times higher than previously assumed. In addition, at T = 100 MK, the revised total reaction rate is a factor of two higher. Note that this is the range of temperature at which the Mg-Al cycle operates in a H-burning zone. The effects of this revision are discussed. Due to the significantly larger {sup 25}Mg(p, {gamma}){sup 26}Al {sup m} rate, the estimated production of {sup 26}Al{sup gs} in H-burning regions is less efficient than previously obtained. As a result, the new rates should imply a smaller contribution from Wolf-Rayet stars to the galactic {sup 26}Al budget. Similarly, we show that the asymptotic giant branch (AGB) extra-mixing scenario does not appear able to explain the most extreme values of {sup 26}Al/{sup 27}Al, i.e., >10{sup -2}, found in some O-rich presolar grains. Finally, the substantial increase of the total reaction rate makes the hypothesis of self-pollution by massive AGBs a more robust explanation for the Mg-Al anticorrelation observed in globular-cluster stars.

  7. Thermal conductivity of MgO and MgSiO3 at lower mantle conditions from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Jahn, S.; Haigis, V.; Salanne, M.

    2011-12-01

    Thermal conductivity is an important physical parameter that controls the heat flow in the Earth's core and mantle. The heat flow from the core to the mantle influences mantle dynamics and the convective regime of the liquid outer core, which drives the geodynamo. Although thermal conductivities of important mantle minerals at ambient pressure are well-known (Hofmeister, 1999), experimentalists encounter major difficulties to measure thermal conductivities at high pressures and temperatures. Extrapolations of experimental data to high pressures have a large uncertainty and hence the heat transport in minerals at conditions of the deep mantle is not well constrained. Recently, the thermal conductivity of MgO at lower mantle conditions was computed from first-principles simulations (e.g. de Koker (2009), Stackhouse et al. (2010)). Here, we used classical molecular dynamics to calculate thermal conductivities of MgO and MgSiO3 in the perovskite and post-perovskite structures at different pressures and temperatures. The interactions between atoms were treated by an advanced ionic interaction model which was shown to describe the behavior of materials reliably within a wide pressure and temperature range (Jahn & Madden, 2007). Two alternative techniques were used and compared. In non-equilibrium MD, an energy flow is imposed on the system, and the thermal conductivity is taken to be inversely proportional to the temperature gradient that builds up in response to this flow. The other technique (which is still too expensive for first principles methods) uses standard equilibrium MD and extracts the thermal conductivity from energy current correlation functions, according to the Green-Kubo formula. As a benchmark for the interaction potential, we calculated the thermal conductivity of fcc MgO at 2000K and 149GPa, where data from ab-initio non-equilibrium MD are available (Stackhouse et al., 2010). The results agree within the error bars, which justifies the use of the

  8. Surface studies of Li-ion and Mg battery electrodes

    NASA Astrophysics Data System (ADS)

    Esbenshade, Jennifer

    rate capabilities relative to a comparable Si thin film electrode. This intercalation behavior found by dimensionally constraining Si lithiation promises applicability to a range of conversion reactions. Improving Electrodeposition of Mg through an Open Circuit Potential Hold: In this section, in situ XRD, XPS, SEM and electrochemical methods were used to interrogate the mechanism of Mg electrodeposition from PhMgCl/AlCl3 (APC) and EtMgCl electrolytes. An open circuit potential (OCP) pause following Mg deposition led to retained enhancement of Mg deposition and stripping kinetics along with lowered overpotentials for both. In situ XRD demonstrated that the OCP pause led to a more polycrystalline deposits relative to that without the pause, while SEM presented micrographs that showed smaller deposits with an OCP hold. The improvement is attributed to an 'enhancement layer' that formed on the electrode during the OCP hold. Analysis of XPS data suggests that this 'enhancement layer' consists of Mg and Cl retained on the electrode surface, possibly following electrode depassivation.

  9. Bioequivalence studies for two different strengths of montelukast in healthy volunteers: 10 mg film-coated tablets and 5 mg chewable tablets.

    PubMed

    Pedroso, P; Almeida, S; Filipe, A; Neves, R I; Boudreault, S; Jiménez, C

    2013-09-01

    In order to assess the bioequivalence of 2 different formulations of montelukast, a pivotal trial for the montelukast 10 mg film-coated tablets formulation and a pivotal trial for the montelukast 5 mg chewable tablets formulation were conducted.For the 10 mg study, 34 healthy subjects were enrolled in a single centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days, while for the 5 mg study, 42 healthy subjects were included in another study with a similar design. For both studies, plasma samples were collected up to 24 h post-dosing and drug levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection.Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC0-t) and from time zero to infinity (AUC0-inf) and maximum observed concentration (Cmax), were determined from the drug concentration data using non-compartmental analysis.In the 10 mg study, the 90% confidence intervals obtained by analysis of variance were 99.62-120.51% for Cmax, 102.25-117.37% for AUC0-t and 101.96-116.67% for AUC0-inf, which were within the predefined acceptable range of 80.00-125.00%.In the 5 mg study, the 90% confidence intervals were 91.14-98.46% for Cmax, 93.02-98.42% for AUC0-t and 93.09-98.63% for AUC0-inf, which were within the predefined acceptable range of 80.00-125.00%.Bioequivalence between formulations was concluded both in terms of rate and extent of absorption for both strengths.

  10. Mg/Ca composition of benthic foraminifera Miliolacea as a new tool of paleoceanography

    NASA Astrophysics Data System (ADS)

    Sadekov, Aleksey Yu.; Bush, Flora; Kerr, Joanna; Ganeshram, Raja; Elderfield, Henry

    2014-10-01

    The Mg/Ca compositions of benthic foraminifera from the superfamily Miliolacea have been studied to explore the use of these high-Mg foraminifera as a proxy for deep ocean conditions. Taxonomic analyses, relative abundance, and depth distributions of different Miliolacea species were carried out on a collection of core top samples, covering a depth range of 131 m to 2530 m, along the Australian coast of the Timor Sea. Pyrgo sp., composed of Pyrgo sarsi and Pyrgo murrhina, was found to be the most suitable for proxy studies. Mg/Ca values of this group of foraminifera show a strong correlation with bottom water temperatures and carbonate ion saturation described by the linear relationship: Mg/Ca = 2.53(±0.22) × BWT + 0.129(±0.023) × Δ[CO32-] + 4.63(±0.53), within the -1°C to 8°C temperature range. Absolute Mg/Ca values of Pyrgo sp. calcite and their temperature sensitivity are similar to those observed for inorganic calcite, suggesting that Mg composition of Pyrgo sp. calcite is mainly controlled by inorganic processes. The Mg/Ca composition of Pyrgo sp. calcite provides a new tool for reconstructing both water temperature and carbonate ion saturation when combined with other proxies for one of these parameters. A down core record from the Eastern Equatorial Pacific has been generated to illustrate how Mg/Ca values can be used for paleoclimate studies. This down core record shows large changes in Pacific bottom waters [CO32-] across glacial-interglacial transition, implying an increase in [CO32-] during the glacial period.

  11. Transition probabilities and radiative lifetimes of Mg III

    NASA Astrophysics Data System (ADS)

    Alonso-Medina, A.; Colón, C.; Moreno-Díaz, C.

    2015-03-01

    There have been calculated transition probabilities for 365 lines arising from 2p5 n s(n = 3 , 4 , 5) , 2p5 n p(n = 3 , 4) , 2p5 n d(n = 3 , 4) , 2p5 n f(n = 4 , 5) and 2p5 5g configurations of Mg III and radiative lifetimes corresponding to 89 levels. These values were obtained in intermediate coupling (IC) by using ab initio relativistic Hartree-Fock (HFR) calculations. Later, we use the standard method of least square fitting of experimental energy levels for the IC calculations by means of Cowan's computer codes. The vast majority of the calculated transition probabilities correspond to lines lying in the ultraviolet range (UV) which are of high interest in astrophysics. Our results are compared to those previously reported in the literature. Furthermore, the values of transition probabilities of configuration levels 2p5 4d, 2p5 n f(n = 4 , 5) and 2p5 5g are presented for the first time. In light of these findings, it is possible to extend the range of wavelengths which allows us to estimate the temperature in plasma diagnostic. In addition, our results for radiative lifetimes have been compared to the available experimental values.

  12. Development of a new thermoluminescent phosphor based on LiF:Mg,Ti

    NASA Astrophysics Data System (ADS)

    Azorín, J.; González, P. R.; Lozano, I. B.; Rivera, T.; Azorin, C.

    2015-11-01

    By a slight modification in the dopants incorporation method, a new LiF:Mg,Ti TLD material has been developed with improved properties mainly in stabilization of thermoluminescent (TL) response and linearity. The TL response as well as linearity function of LiF:Mg,Ti under 60Co gamma irradiation were studied in the dose range from 10-3 to 103 Gy. The TL response as a function of gamma dose was linear from 2.5 mGy up to 50 Gy. Experimental results indicated that LiF:Mg,Ti synthesized in Mexico shows high stability and a wide range of linearity. Improvement in linearity could be attributed to Ti concentration. Kinetic parameters were determined by deconvolution of glow curves. Experimental results suggest that this new TLD material shows promising potential for gamma radiation dosimetry.

  13. On the metallicity dependence of the [Y/Mg]-age relation for solar-type stars

    NASA Astrophysics Data System (ADS)

    Feltzing, Sofia; Howes, Louise M.; McMillan, Paul J.; Stonkutė, Edita

    2017-02-01

    Several recent studies of solar twins in the solar neighbourhood have shown a tight correlation between various elemental abundances and age, in particular [Y/Mg]. If this relation is real and valid for other types of stars as well as elsewhere in the Galaxy, it would provide a very powerful tool to derive ages of stars without the need to resort to determining their masses (evolutionary stage) very precisely. The method would also likely work if the stellar parameters have relatively large errors. The studies presented in the recent literature span a narrow range of [Fe/H]. By studying a larger sample of solar neighbourhood dwarfs with a much larger range of [Fe/H], we find that the relation between [Y/Mg] and age depends on the [Fe/H] of the stars. Hence, it appears that the [Y/Mg]-age relation is unique to solar analogues.

  14. Effect of mechanical vibrations on grain refinement of AZ91 Mg alloy

    NASA Astrophysics Data System (ADS)

    Chaturvedi, Vatsala; Sharma, Ashok; Pandel, Upender

    2017-04-01

    AZ91 Mg alloys are extensively being consumed in the automotive, aerospace, electrical and communication industries. The large freezing range of this alloy allows the formation of coarse-grained structures. To overcome this problem magnesium alloys are, therefore, treated for grain refinement. In this study, mechanical vibrations in the frequency range from 0 to 25 Hz at a constant amplitude of 2 mm were imposed during solidification of Mg-9Al-1Zn alloy. Optimum results were obtained at 15 Hz. It was observed that mechanical vibration during solidification had a good refining effect on the grain morphology of the alloy. The alloy was characterized by optical metallography, scanning electron microscopy and mechanical properties such as hardness and tensile strength. It was observed that, by applying vibrations to the melt, a uniform distribution of the fine grains of the primary α-Mg phase was achieved and the properties were enhanced.

  15. Report on the sintering and properties of MgO and MgO-5% TiC

    SciTech Connect

    Bengisu, M.; Inal, O.T.

    1992-07-01

    Sintering of technical grade MgO yields higher fractional densities compared to pure MgO. TiC reacts with MgO under sintering of MgO-TiC composites in air, yielding Mg{sub 2}TiO{sub 4} and CO or CO{sub 2}. This can be suppressed in vacuum by plasma sintering. Plasma sintering of MgO at 1300 C and short times does not produce satisfactory results. 5 vol% TiC increases the sinterability of MgO during conventional air sintering; larger additions (50 vol%) decrease sinterability due to macropores formed by gaseous reaction product. Microwave sintering of MgO is possible. Mechanical properties of MgO are improved by additions of small amounts of TiC to starting powders.

  16. Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

    NASA Astrophysics Data System (ADS)

    Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

    2016-10-01

    In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase JSC of the surface while slightly decreasing VOC compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  17. Hydrogen storage and phase transformations in Mg-Pd nanoparticles

    NASA Astrophysics Data System (ADS)

    Callini, E.; Pasquini, L.; Rude, L. H.; Nielsen, T. K.; Jensen, T. R.; Bonetti, E.

    2010-10-01

    Microstructure refinement and synergic coupling among different phases are currently explored strategies to improve the hydrogen storage properties of traditional materials. In this work, we apply a combination of these methods and synthesize Mg-Pd composite nanoparticles by inert gas condensation of Mg vapors followed by vacuum evaporation of Pd clusters. Irreversible formation of the Mg6Pd intermetallic phase takes place upon vacuum annealing, resulting in Mg/Mg6Pd composite nanoparticles. Their hydrogen storage properties are investigated and connected to the undergoing phase transformations by gas-volumetric techniques and in situ synchrotron radiation powder x-ray diffraction. Mg6Pd transforms reversibly into different Mg-Pd intermetallic compounds upon hydrogen absorption, depending on temperature and pressure. In particular, at 573 K and 1 MPa hydrogen pressure, the metal-hydride transition leads to the formation of Mg3Pd and Mg5Pd2 phases. By increasing the pressure to 5 MPa, the Pd-richer MgPd intermetallic is obtained. Upon hydrogen desorption, the Mg6Pd phase is reversibly recovered. These phase transformations result in a specific hydrogen storage capacity associated with Mg-Pd intermetallics, which attain the maximum value of 3.96 wt % for MgPd and influence both the thermodynamics and kinetics of hydrogen sorption in the composite nanoparticles.

  18. Photodissociation spectroscopy of the Mg{sup +}-acetic acid complex

    SciTech Connect

    Abate, Yohannes; Kleiber, P. D.

    2006-11-14

    We have studied the structure and photodissociation of Mg{sup +}-acetic acid clusters. Ab initio calculations suggest four relatively strongly bound ground state isomers for the [MgC{sub 2}H{sub 4}O{sub 2}]{sup +} complex. These isomers include the cis and trans forms of the Mg{sup +}-acetic acid association complex with Mg{sup +} bonded to the carbonyl O atom of acetic acid, the Mg{sup +}-acetic acid association complex with Mg{sup +} bonded to the hydroxyl O atom of acetic acid, or to a Mg{sup +}-ethenediol association complex. Photodissociation through the Mg{sup +}-based 3p<-3s absorption bands in the near UV leads to direct (nonreactive) and reactive dissociation products: Mg{sup +}, MgOH{sup +}, Mg(H{sub 2}O){sup +}, CH{sub 3}CO{sup +}, and MgCH{sub 3}{sup +}. At low energies the dominant reactive quenching pathway is through dehydration to Mg(H{sub 2}O){sup +}, but additional reaction channels involving C-H and C-C bond activation are also open at higher energies.

  19. A fundamental study on the [(μ-Cl)3 Mg2 (THF)6 ]+ dimer electrolytes for rechargeable Mg batteries

    DOE PAGES

    Liu, Tianbiao; Cox, Jonathan T.; Hu, Dehong; ...

    2015-01-05

    We present a fundamental study on [(μ-Cl)3 Mg2 (THF)6 ]+ dimer electrolytes using various physical methods including Subambient Pressure Ionization with Nanoelectrospray Mass spectrometry (SPIN-MS), Raman spectroscopy, 25Mg{1H} NMR, 27Al{1H} NMR and electrochemical analysis. For the first time, long time sought THF solvated [MgCl]+ species was experimentally characterized by SPIN mass spectrometry in the solution of the Mgdimer containing electrolyte, confirming the mono-Cl- abstraction reaction between MgCl2 and an Al Lewis acid. Solvated MgCl2 in the electrolyte was confirmed by Raman spectroscopy. The experimental results establish the previously proposed dimerization equilibrium of solvated [MgCl]+ and MgCl2 with [(μ-Cl)3Mg2(THF)6]+.more » 25Mg{1H} NMR, 27Al{1H} NMR and electrochemical analysis on chloration reaction of [(μ-Cl)3Mg2(THF)6]AlPh3Cl with external Cl- led to further insights on the coordination chemistry of the dimer electrolyte. Finally, a comprehensive mechanism is proposed for the reversible electrochemical Mg deposition and stripping and Mg2+ and Cl- ion transports of the Mg dimer electrolytes in rechargeable Mg batteries.« less

  20. A systematic study of (25)Mg NMR in paramagnetic transition metal oxides: applications to Mg-ion battery materials.

    PubMed

    Lee, Jeongjae; Seymour, Ieuan D; Pell, Andrew J; Dutton, Siân E; Grey, Clare P

    2016-12-21

    Rechargeable battery systems based on Mg-ion chemistries are generating significant interest as potential alternatives to Li-ion batteries. Despite the wealth of local structural information that could potentially be gained from Nuclear Magnetic Resonance (NMR) experiments of Mg-ion battery materials, systematic (25)Mg solid-state NMR studies have been scarce due to the low natural abundance, low gyromagnetic ratio, and significant quadrupole moment of (25)Mg (I = 5/2). This work reports a combined experimental (25)Mg NMR and first principles density functional theory (DFT) study of paramagnetic Mg transition metal oxide systems Mg6MnO8 and MgCr2O4 that serve as model systems for Mg-ion battery cathode materials. Magnetic parameters, hyperfine shifts and quadrupolar parameters were calculated ab initio using hybrid DFT and compared to the experimental values obtained from NMR and magnetic measurements. We show that the rotor assisted population transfer (RAPT) pulse sequence can be used to enhance the signal-to-noise ratio in paramagnetic (25)Mg spectra without distortions in the spinning sideband manifold. In addition, the value of the predicted quadrupolar coupling constant of Mg6MnO8 was confirmed using the RAPT pulse sequence. We further apply the same methodology to study the NMR spectra of spinel compounds MgV2O4 and MgMn2O4, candidate cathode materials for Mg-ion batteries.

  1. The effect of Mg location on Co-Mg-Ru/γ-Al2O3 Fischer–Tropsch catalysts

    PubMed Central

    Combes, Gary B.; Ozkaya, Don; Enache, Dan I.; Ellis, Peter R.; Kelly, Gordon; Rosseinsky, Matthew J.

    2016-01-01

    The effectiveness of Mg as a promoter of Co-Ru/γ-Al2O3 Fischer–Tropsch catalysts depends on how and when the Mg is added. When the Mg is impregnated into the support before the Co and Ru addition, some Mg is incorporated into the support in the form of MgxAl2O3+x if the material is calcined at 550°C or 800°C after the impregnation, while the remainder is present as amorphous MgO/MgCO3 phases. After subsequent Co-Ru impregnation MgxCo3−xO4 is formed which decomposes on reduction, leading to Co(0) particles intimately mixed with Mg, as shown by high-resolution transmission electron microscopy. The process of impregnating Co into an Mg-modified support results in dissolution of the amorphous Mg, and it is this Mg which is then incorporated into MgxCo3−xO4. Acid washing or higher temperature calcination after Mg impregnation can remove most of this amorphous Mg, resulting in lower values of x in MgxCo3−xO4. Catalytic testing of these materials reveals that Mg incorporation into the Co oxide phase is severely detrimental to the site-time yield, while Mg incorporation into the support may provide some enhancement of activity at high temperature. PMID:26755760

  2. Nanocrystalline MgMnSiO4 and MgCoSiO4 particles for rechargeable Mg-ion batteries

    NASA Astrophysics Data System (ADS)

    Truong, Quang Duc; Devaraju, Murukanahally Kempaiah; Honma, Itaru

    2017-09-01

    Magnesium-ion batteries hold promise as next-generation secondary battery systems owing to its low cost, safety and high volumetric capacity. Magnesium metal silicates exhibit potential electrode materials with high specific capacities. However, the strong electrostatic interaction between Mg2+ and host lattice due to its divalency as well as antisite cation exchange, induces slow intercalation kinetics of Mg ions within the crystal lattices. Thus, nanocrystalline particles with shortened Mg ion diffusion distance enable the insertion/extraction of Mg ions and improve specific capacities of the batteries. Herein, we report the low-temperature production of crystalline MgMnSiO4 and MgCoSiO4 nanoparticles by a rapid supercritical fluid processing. The extraction of magnesium ions from the olivine framework has been confirmed by X-ray photoelectron spectroscopy, revealing its ability as active materials for magnesium-ion battery.

  3. Optical range and range rate estimation for teleoperator systems

    NASA Technical Reports Server (NTRS)

    Shields, N. L., Jr.; Kirkpatrick, M., III; Malone, T. B.; Huggins, C. T.

    1974-01-01

    Range and range rate are crucial parameters which must be available to the operator during remote controlled orbital docking operations. A method was developed for the estimation of both these parameters using an aided television system. An experiment was performed to determine the human operator's capability to measure displayed image size using a fixed reticle or movable cursor as the television aid. The movable cursor was found to yield mean image size estimation errors on the order of 2.3 per cent of the correct value. This error rate was significantly lower than that for the fixed reticle. Performance using the movable cursor was found to be less sensitive to signal-to-noise ratio variation than was that for the fixed reticle. The mean image size estimation errors for the movable cursor correspond to an error of approximately 2.25 per cent in range suggesting that the system has some merit. Determining the accuracy of range rate estimation using a rate controlled cursor will require further experimentation.

  4. Optical range and range rate estimation for teleoperator systems

    NASA Technical Reports Server (NTRS)

    Shields, N. L., Jr.; Kirkpatrick, M., III; Malone, T. B.; Huggins, C. T.

    1974-01-01

    Range and range rate are crucial parameters which must be available to the operator during remote controlled orbital docking operations. A method was developed for the estimation of both these parameters using an aided television system. An experiment was performed to determine the human operator's capability to measure displayed image size using a fixed reticle or movable cursor as the television aid. The movable cursor was found to yield mean image size estimation errors on the order of 2.3 per cent of the correct value. This error rate was significantly lower than that for the fixed reticle. Performance using the movable cursor was found to be less sensitive to signal-to-noise ratio variation than was that for the fixed reticle. The mean image size estimation errors for the movable cursor correspond to an error of approximately 2.25 per cent in range suggesting that the system has some merit. Determining the accuracy of range rate estimation using a rate controlled cursor will require further experimentation.

  5. Characterisation of magnesium oxide and its interface with α-Mg in Mg-Al-based alloys

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Fan, Z.; Zhou, X.; Thompson, G. E.

    2011-08-01

    Magnesium oxide (MgO) films and particles have been collected by pressurised filtration of a Mg-8.6wt%Al-0.67wt%Zn (AZ91D) alloy melt. The morphology of the oxides and their interfaces with the α-Mg phase were investigated by high-resolution transmission electron microscopy. It was found that the oxide films consisted of large numbers of sub-micrometre-sized MgO particles, and that melt shearing can effectively break up the oxide films and disperse the oxide particles. For the first time, orientation relationships (ORs) of OR I: [1 overline 1 1]MgO∼2° from (0 0 0 1)α-Mg and (0 1 1)MgO //[2 overline 1 overline 1 0)α-Mg; and OR II: (overline 1 overline 1 1)MgO//(1 overline 1 0 1)α-Mg and [0 1 1]MgO//[overline 1 2 overline 1 1]α-Mg, were observed between the MgO particles and the α-Mg matrix. The calculated Bramfitt planar disregistries were 5.5% and 2.5% for the two ORs, respectively, indicating good lattice matching between MgO and α-Mg at the interface. With the evidence of grain refinement effect observed in the sheared AZ91D magnesium alloy, the possibility of MgO particles to act as potent nucleants for heterogeneous nucleation of α-Mg grains is discussed in terms of the crystallographic criterion.

  6. Amplified spontaneous and stimulated Mg L emissions from MgO pumped by FEL pulses

    NASA Astrophysics Data System (ADS)

    Jonnard, Philippe; André, Jean-Michel; Le Guen, Karine; Wu, Meiyi; Principi, Emiliano; Simoncig, Alberto; Gessini, Alessandro; Mincigrucci, Riccardo; Masciovecchio, Claudio; Peyrusse, Olivier

    2017-05-01

    Stimulated emission is a fundamental process in nature that deserves to be investigated and understood in the EUV and X-ray regimes. Today this is definitely possible through high energy density FEL beams. In this context, we show evidence for soft x-ray stimulated emission from a MgO solid target pumped by extreme ultraviolet FEL pulses formed in the regime of travelling-wave amplified spontaneous emission in backward geometry. Our results combine two effects separately reported in previous works: emission in a privileged direction and existence of a material-dependent threshold, for the stimulated emission. We have developed a theoretical framework, based on coupled rate and transport equations taking into account the solid density plasma state of the target. Our model, accounts for both observed mechanisms that are the privileged direction for the stimulated emission of the Mg L2,3 characteristic emission and the pumping threshold.

  7. Understanding and Enhancing Hydrogen Diffusion in MgH2 and NaMgH3

    NASA Astrophysics Data System (ADS)

    Sholl, David; Hao, Shiqiang

    2009-03-01

    The transport properties of hydrogen in metal hydrides are crucial to the kinetics of H2 storage in these materials. We use first-principles calculations to identify the defects that are relevant for H transport in MgH2 and NaMgH3. In both materials, the physically relevant defects are charged and H diffusion is dominated by mobility of negatively charged interstitial H. Interestingly, the diffusion of these species occurs via concerted mechanisms with low energy barriers. To improve the charged interstitial H diffusivity, a series of transition-metal additives are screened to lower the formation energy of mobile defects. Our results provide a practical way to examine and alter H diffusion in light metal hydrides.

  8. Phosphate Capacities of CaF2-MgO and CaF2-CaO-MgO Slags

    NASA Astrophysics Data System (ADS)

    Akbari, F.; Pickles, C. A.

    2015-02-01

    Previously published sulphide capacity data and thermodynamic arguments have been employed to calculate the phosphate capacities and the phosphorus partition ratios between a molten carbon saturated iron alloy and binary CaF2-MgO slags and also ternary CaF2 -CaO-MgO slags at 1450 °C. For the CaF2-MgO binary system, a linear relationship was found between the phosphate and the sulphide capacities as follows: log ? = 1.2 log Cs + 25.2. For the ternary CaF2-CaO-MgO system at 1450 °C, the logarithm of the calculated phosphate capacities ranged from 19.47 to 20.15. With the addition of CaO, the phosphate capacities initially increased, reached a maximum and then decreased slightly. The addition of MgO to the CaF2-CaO system resulted in a decrease in the phosphate capacity. The calculated phosphorus partition ratios increased slightly with increasing mole fraction of CaO in the ternary system.

  9. Geographic range limits: achieving synthesis

    PubMed Central

    Gaston, Kevin J.

    2009-01-01

    Understanding of the determinants of species' geographic range limits remains poorly integrated. In part, this is because of the diversity of perspectives on the issue, and because empirical studies have lagged substantially behind developments in theory. Here, I provide a broad overview, drawing together many of the disparate threads, considering, in turn, how influences on the terms of a simple single-population equation can determine range limits. There is theoretical and empirical evidence for systematic changes towards range limits under some circumstances in each of the demographic parameters. However, under other circumstances, no such changes may take place in particular parameters, or they may occur in a different direction, with limitation still occurring. This suggests that (i) little about range limitation can categorically be inferred from many empirical studies, which document change in only one demographic parameter, (ii) there is a need for studies that document variation in all of the parameters, and (iii) in agreement with theoretical evidence that range limits can be formed in the presence or absence of hard boundaries, environmental gradients or biotic interactions, there may be few general patterns as to the determinants of these limits, with most claimed generalities at least having many exceptions. PMID:19324809

  10. Phase relations and formation of chromium-rich phases in the system Mg4Si4O12-Mg3Cr2Si3O12 at 10-24 GPa and 1,600 °C

    NASA Astrophysics Data System (ADS)

    Sirotkina, E. A.; Bobrov, A. V.; Bindi, L.; Irifune, T.

    2015-01-01

    Phase relations in the system Mg4Si4O12-Mg3Cr2Si3O12 were studied at 10-24 GPa and 1,600 °C using a high-pressure Kawai-type multi-anvil apparatus. We investigated the full range of starting compositions for the knorringite-majorite system to derive a P- X phase diagram and synthesize garnets of a wide compositional range. Samples synthesized in the pressure range 10-14 GPa contain knorringite-majorite garnet and Cr-bearing pyroxene. With increasing Cr content in the starting materials, an association of knorringite-majorite garnet and eskolaite is formed. Garnets contain a significant portion of majorite (>10 mol%) even for a pure Mg3Cr2Si3O12 starting composition. Knorringite-majorite garnets were obtained in the pressure range from 10 to 20 GPa. With increasing pressure, the phase assemblages include Cr-bearing MgSiO3 akimotoite and MgSiO3 bridgmanite, as well as MgCr2O4 with calcium titanate structure, and stishovite. Single-crystal X-ray diffraction shows that the incorporation of Cr into the structure of garnet, as well as MgSiO3 akimotoite, and bridgmanite results in an increase in their unit cell parameters. Results of the experimental high-pressure investigation of the pseudo-binary system Mg4Si4O12-Mg3Cr2Si3O12 (SiO2-MgO-Cr2O3) may be applied to the origin of high chromium phases (mostly garnet) found as inclusions in peridotitic diamonds and formed in bulk rock compositions with high Cr/Al ratios in relation to the primitive mantle.

  11. 3D [Ag-Mg] polyanionic frameworks in the La 4Ag 10Mg 3 and La 4Ag 10.3Mg 12 new ternary compounds

    NASA Astrophysics Data System (ADS)

    Solokha, Pavlo; De Negri, Serena; Pavlyuk, Volodymyr; Eck, Bernhard; Dronskowski, Richard; Saccone, Adriana

    2010-12-01

    The crystal structures of two new ternary phases, La 4Ag 10Mg 3 and La 4Ag 10.3Mg 12, were refined from X-ray single crystal diffraction data. La 4Ag 10Mg 3 crystallizes in the Ca 4Au 10In 3 structure type, an ordered variant of the binary Zr 7Ni 10 compound: orthorhombic, Cmce, oS68, a=14.173(5), b=10.266(3), c=10.354(3) Å, Z=4, w R2=0.0826, 676 F2 values, 50 variables. La 4Ag 10.3Mg 12 represents a new structure type: orthorhombic, Cmmm, oS116-10.32, a=9.6130(3), b=24.9663(8), c=9.6333(2) Å, Z=4, w R2=0.0403, 1185 F2 values, 101 variables. The structural analysis of both compounds, highlighting a significant contraction of the Ag-Mg distances, suggests the existence of three-dimensional [Ag-Mg] networks hosting La atoms. LMTO calculations applied to La 4Ag 10Mg 3 indicate that the strongest bonds occur for Ag-Ag and Ag-Mg interactions, and confirm the presence of a 3D ∞[Ag 10Mg 3] δ- polyanionic framework balanced by positively charged La atoms.

  12. Sphingolipids regulate [Mg2+]o uptake and [Mg2+]i content in vascular smooth muscle cells: potential mechanisms and importance to membrane transport of Mg2+.

    PubMed

    Zheng, Tao; Li, Wenyan; Altura, Bella T; Shah, Nilank C; Altura, Burton M

    2011-02-01

    Sphingolipids have a variety of important signaling roles in mammalian cells. We tested the hypothesis that certain sphingolipids and neutral sphingomyelinase (N-SMase) can regulate intracellular free magnesium ions ([Mg2+]i) in vascular smooth muscle (VSM) cells. Herein, we show that several sphingolipids, including C2-ceramide, C8-ceramide, C16-ceramide, and sphingosine, as well as N-SMase, have potent and direct effects on content and mobilization of [Mg2+]i in primary cultured rat aortic smooth muscle cells. All of these sphingolipid molecules increase, rapidly, [Mg2+]i in these vascular cells in a concentration-dependent manner. The increments of [Mg2+]i, induced by these agents, are derived from influx of extracellular Mg2+ and are extracellular Ca2+ concentration-dependent. Phospholipase C and Ca2+/calmodulin/Ca2+-ATPase activity appear to be important in the sphingolipid-induced rises of [Mg2+]i. Activation of certain PKC isozymes may also be required for sphingolipid-induced rises in [Mg2+]i. These novel results suggest that sphingolipids may be homeostatic regulators of extracellular Mg2+ concentration influx (and transport) and [Mg2+]i content in vascular muscle cells.

  13. Structure and Properties of Single Crystalline CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2

    SciTech Connect

    May, Andrew F; McGuire, Michael A; Singh, David J; Custelcean, Radu; Jellison Jr, Gerald Earle

    2011-01-01

    Single crystals of CaMg{sub 2}Bi{sub 2}, EuMg{sub 2}Bi{sub 2}, and YbMg{sub 2}Bi{sub 2} were obtained from a Mg-Bi flux cooled to 650 C. These materials crystallize in the CaAl{sub 2}Si{sub 2} structure-type (P3{bar m}1, No. 164), and crystal structures are reported from refinements of single crystal and powder X-ray diffraction data. EuMg{sub 2}Bi{sub 2} displays an antiferromagnetic transition near 7 K, which is observed via electrical resistivity, magnetization, and specific heat capacity measurements. Magnetization measurements on YbMg{sub 2}Bi{sub 2} reveal a weak diamagnetic moment consistent with divalent Yb. Despite charge-balanced empirical formulas, all three compounds are p-type conductors with Hall carrier concentrations of 2.0(3) x 10{sup 19} cm{sup -3} for CaMg{sub 2}Bi{sub 2}, 1.7(1) x 10{sup 19} cm{sup -3} for EuMg{sub 2}Bi{sub 2}, and 4.6(7) x 10{sup 19} cm{sup -3} for YbMg{sub 2}Bi{sub 2}, which are independent of temperature to 5 K. The electrical resistivity decreases with decreasing temperature and the resistivity ratios {rho}(300 K)/{rho}(10 K) {le} 1.6 in all cases, indicating significant defect scattering.

  14. Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

    NASA Astrophysics Data System (ADS)

    Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

    2017-04-01

    There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

  15. Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

    NASA Astrophysics Data System (ADS)

    Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

    2016-12-01

    There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

  16. Comparison of the pharmacokinetics of lansoprazole 15- and 30-mg sachets for suspension versus intact capsules.

    PubMed

    Amer, Fouad; Karol, Michael D; Pan, Wei-Jian; Griffin, Janice S; Lukasik, Nancy L; Locke, Charles S; Chiu, Yi-Lin

    2004-12-01

    The pharmacokinetic profiles of single doses of lansoprazole 15- and 30-mg sachets for suspension were compared with those of corresponding doses of lansoprazole oral capsules. Healthy adult male and female subjects were randomized (1:1 ratio) into 2 Phase 1, open-label, single-dose, 2-sequence, 2-period complete crossover studies. In the first study, each subject received 1 lansoprazole 15-mg sachet mixed with water and 1 lansoprazole 15-mg oral capsule; in the second study, each subject received 1 lansoprazole 30-mg sachet mixed with water and 1 lansoprazole 30-mg oral capsule. Administration of the 2 formulations was separated by a washout period of > or =7 days. Blood samples were collected before and after each administration to assess the pharmacokinetic parameters of lansoprazole and bioequivalence between suspension and capsule. Thirty-six subjects (19 males, 17 females) with a mean (SD) age of 32.0 (9.6) years and mean (SD) body weight of 68.6 (10.5) kg received lansoprazole 15 mg. Thirty-six subjects (22 males, 14 females) with a mean (SD) age of 38.0 (8.3) years and mean (SD) body weight of 75.1 (9.7) kg received lansoprazole 30 mg. The pharmacokinetic parameters of the 15- and 30-mg lansoprazole sachets for suspension were similar to those of the corresponding doses of the oral capsules. The mean (SD) values for C(max) and AUC from time 0 to infinity (AUC(0-infinity) for the lansoprazole 15-mg sachet (591.9 [242.3] ng/mL and 1614 [2065] ng.h/mL, respectively) did not differ significantly from those for the lansoprazole 15-mg capsules (578.6 [275.2] ng/mL and 1620 [2290] ng.h/mL, respectively). These parameters also did not differ significantly between the lansoprazole 30-mg sachet and 30-mg capsule: mean (SD) C(max), 1103 (428.3) and 1077 (465.6) ng/mL, respectively; mean (SD) AUC(0-infinity), 2655 (1338) and 2669 (1311) ng.h/mL, respectively. The 90% Cls for C(max) and AUC(0-infinity) ratios were contained within the 0.80 to 1.25 equivalence range

  17. Effect of Melt-to-Solid Insert Volume Ratio on Mg/Al Dissimilar Metals Bonding

    NASA Astrophysics Data System (ADS)

    Emami, S. M.; Divandari, M.; Arabi, H.; Hajjari, E.

    2013-01-01

    Compound casting is used as a process to join various similar and dissimilar metallic couples. The ratio of melt-to-solid volume is one of the main factors that can affect the contact time between melt and the solid insert. In this investigation, magnesium and aluminum metals (magnesium as the cast metal and aluminum as the solid insert) having melt-to-solid volume ratios ( V m/ V s) of 1.25, 3, and 5.25 were successfully bonded via compound casting. Results demonstrated that by increasing the ratio of V m/ V s from 1.25 to 5.25, the thickness of the reaction interface between Al and Mg varies within the range of 200 to 1800 μm. X-ray diffraction, scanning electron microscopy, and Vickers microhardness study of the bonding of these two metals showed that the interface consisted of three separate sub-layers within reaction layer. These sub-layers had higher hardness than those of the Al and Mg bulk metals. In all specimens, composition of the sub-layer adjacent to Al (layer I) was Al3Mg2 and that adjacent to Mg (layer III) was Al12Mg17/(Mg) eutectic structure. The intermediate layer composition (layer II) in specimens with volume ratio of 1.25 and 3 was a single-phase Al12Mg17, while for the case of volume ratio 5.25 this sub-layer consisted of Al12Mg17/(Mg) eutectic dispersed in Al12Mg17 intermetallic. The results of this research showed that in low melt/solid volume ratios, diffusion-reaction was the dominant mechanism for formation of Al-Mg intermetallic. However, when V m/ V s and the melt/solid insert contact time increased, the dominant mechanism of Al-Mg intermetallics changed to fusion-solidification due to increase in surface melting of the solid insert. Also the results of push-out tests showed that shear strengths of the interface decrease from 27.1 to 15.1 and 8.3 MPa for the Al/Mg couples prepared at 1.25, 3, and 5.25 V m/ V s respectively.

  18. Origin of low δ26Mg Cenozoic basalts from South China Block and their geodynamic implications

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Li, Shu-Guang; Xiao, Yilin; Ke, Shan; Li, Wang-Ye; Tian, Ye

    2015-09-01

    Origin of low δ26Mg basalts is a controversial subject and has been attributed to interaction of isotopically light carbonatitic melts derived from a subducted oceanic slab with the mantle (Yang et al., 2012), or alternatively, to accumulation of isotopically light ilmenite (FeTiO3) in their mantle source (Sedaghatpour et al., 2013). To study the origin of low δ26Mg basalts and evaluate whether Mg isotope ratios of basalts can be used to trace deeply recycled carbon, high-precision major and trace element and Mg isotopic analyses on the Cenozoic alkaline and tholeiitic basalts from the South China Block (SCB), eastern China have been carried out in this study. The basalts show light Mg isotopic compositions, with δ26Mg ranging from -0.60 to -0.35. The relatively low TiO2 contents (<2.7 wt.%) of our basalts, roughly positive correlations between δ26Mg and Ti/Ti∗ and their constant Nb/Ta ratios (16.4-20) irrespective of variable TiO2 contents indicate no significant amounts of isotopically light ilmenite accumulation in their mantle source. Notably, the basalts display negative correlations between δ26Mg and the amounts of total alkalis (i.e., Na2O + K2O) and incompatible trace elements (e.g., Ti, La, Nd, Nb, Th) and trace element abundance ratios (e.g., Sm/Yb, Nb/Y). Generally, with decrease of δ26Mg values, their Hf/Hf∗ and Ti/Ti∗ ratios decrease, whereas Ca/Al and Zr/Hf ratios increase. These features are consistent with incongruent partial melting of an isotopically light carbonated mantle, suggesting that large variations in Mg isotope ratios occurred during partial melting of such carbonated mantle under high temperatures. The isotopically light carbonated mantle were probably formed by interaction of the mantle with low δ26Mg carbonatitic melts derived from the deeply subducted low δ26Mg carbonated eclogite transformed from carbonate-bearing oceanic crust during plate subduction. As only the Pacific slab has an influence on both the North China

  19. Characterization of MgB2 Conductors for Coil Development

    NASA Astrophysics Data System (ADS)

    Aslanoglu, Z.; Arda, L.; Akin, Y.; Sumption, M. D.; Tomsic, M.; Hascicek, Y. S.

    2004-06-01

    The effects of the heat treatment conditions on microstructure and the transport critical current density of MgB2 wires, which were fabricated by the Continuous Tube Forming and Filling (CTFF) process, have been investigated. Two types of MgB2 conductors, Fe/MgB2 and Cu/MgB2, were studied. It was found that the sheath materials affect the optimum annealing profile of MgB2 conductor. The annealing temperature for Cu/MgB2 conductors was lower than that for the Fe/MgB2 conductors. The critical current density, Jc was measured to be 1.1×105 A/cm2 at 20 K in-self field for Cu/MgB2 conductor of 1.25 mm in diameter. The processing, microstructure and superconducting properties are presented.

  20. The possibility of forming a sacrificial anode coating for Mg

    SciTech Connect

    Dudney, Nancy J; Li, Juchuan; Sacci, Robert L; Thomson, Jeffery K

    2014-01-01

    Mg is the most active engineering metal, and is often used as a sacrificial anode/coating to protect other engineering metals from corrosion attack. So far no sacrificial anode coating has been developed or considered for Mg. This study explores the possibility of forming a sacrificial coating for Mg. A lithiated carbon coating and a metaphosphated coating are applied on the Mg surface, respectively, and their open-circuit-potentials are measured in saturated Mg(OH)2 solution. They exhibit more negative potentials than bare Mg. SEM reveals that the metaphosphated coating offers more effective and uniform protection for Mg than the lithiated carbon coating. These preliminary results indicate that development of a sacrificial anode coating for Mg is indeed possible.

  1. [Fluconazole 1200mg or 800mg for cryptococcal meningitis treatment in Ivory Coast].

    PubMed

    Kouakou, G A; Ello, N F; Kassi, N A; Keita, M; Doumbia, A; Mossou, C; Kassi, F K; Tanon, A; Ehui, E; Eholié, S P

    2017-03-01

    Assessing the use of high-dose fluconazol monotherapy (1200mg or 800mg) in the treatment and prognosis of HIV-associated cryptococcal meningitis in Ivory Coast. A retrospective study carried out from August 2008 to August 2011 based on patients charts suffering from CM in the Abidjan Tropicals and Infectious Disease Unit. Mortality rate and associated factors were analyzed. Forty-six cases of cryptococcal meningitis (2.5% of hospitalizations) were included. The sex-ratio was of 1.2. The median age was 40.5 [35-47] years. The symptomatology was subacute (93.5%). The main clinical symptoms were syndrome of pure meningeal irritation (65%), fever (100%); 35% of patients had encephalomeningits. Twenty-one (45.7%) was ART-naïve patients. Fluconazole 1200mg was prescribed to 29 (63%) patients. Therapeutic lumbar punctures were performed in 42 (91.3) patients. The mortality rate was 50%. Significant predictors of mortality were encephalomeningitis and therapeutic lumbar puncture. Cryptococcal meningitis associated mortality remains high despite the use of high-dose fluconazole monotherapy. Therapeutic lumbar punctures help to improving the prognosis. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  2. Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

    DOE PAGES

    Neumayer, Sabine M.; Ivanov, Ilia N.; Manzo, Michele; ...

    2015-12-08

    Controlling ferroelectric switching in Mg doped lithium niobate (Mg: LN) is of fundamental importance for optical device and domain wall electronics applications that require precise domain patterns. Stable ferroelectric switching has been previously observed in undoped LN layers above proton exchanged (PE) phases that exhibit reduced polarization, whereas PE layers have been found to inhibit lateral domain growth. Here, Mg doping, which is known to significantly alter ferroelectric switching properties including coercive field and switching currents, is shown to inhibit domain nucleation and stability in Mg: LN above buried PE phases that allow for precise ferroelectric patterning via domain growthmore » control. Furthermore, piezoresponse force microscopy (PFM) and switching spectroscopy PFM reveal that the voltage at which polarization switches from the "up" to the "down" state increases with increasing thickness in pure Mg: LN, whereas the voltage required for stable back switching to the original "up" state does not exhibit this thickness dependence. This behavior is consistent with the presence of an internal frozen defect field. The inhibition of domain nucleation above PE interfaces, observed in this study, is a phenomenon that occurs in Mg: LN but not in undoped samples and is mainly ascribed to a remaining frozen polarization in the PE phase that opposes polarization reversal. This reduced frozen depolarization field in the PE phase also influences the depolarization field of the Mg: LN layer above due to the presence of uncompensated polarization charge at the PE-Mg: LN boundary. Furthermore, these alterations in internal electric fields within the sample cause long-range lattice distortions in Mg: LN via electromechanical coupling, which were corroborated with complimentary Raman measurements.« less

  3. Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

    SciTech Connect

    Neumayer, Sabine M.; Rodriguez, Brian J. E-mail: brian.rodriguez@ucd.ie; Ivanov, Ilia N.; Manzo, Michele; Gallo, Katia E-mail: brian.rodriguez@ucd.ie; Kholkin, Andrei L.

    2015-12-14

    Controlling ferroelectric switching in Mg doped lithium niobate (Mg:LN) is of fundamental importance for optical device and domain wall electronics applications that require precise domain patterns. Stable ferroelectric switching has been previously observed in undoped LN layers above proton exchanged (PE) phases that exhibit reduced polarization, whereas PE layers have been found to inhibit lateral domain growth. Here, Mg doping, which is known to significantly alter ferroelectric switching properties including coercive field and switching currents, is shown to inhibit domain nucleation and stability in Mg:LN above buried PE phases that allow for precise ferroelectric patterning via domain growth control. Furthermore, piezoresponse force microscopy (PFM) and switching spectroscopy PFM reveal that the voltage at which polarization switches from the “up” to the “down” state increases with increasing thickness in pure Mg:LN, whereas the voltage required for stable back switching to the original “up” state does not exhibit this thickness dependence. This behavior is consistent with the presence of an internal frozen defect field. The inhibition of domain nucleation above PE interfaces, observed in this study, is a phenomenon that occurs in Mg:LN but not in undoped samples and is mainly ascribed to a remaining frozen polarization in the PE phase that opposes polarization reversal. This reduced frozen depolarization field in the PE phase also influences the depolarization field of the Mg:LN layer above due to the presence of uncompensated polarization charge at the PE-Mg:LN boundary. These alterations in internal electric fields within the sample cause long-range lattice distortions in Mg:LN via electromechanical coupling, which were corroborated with complimentary Raman measurements.

  4. Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

    SciTech Connect

    Neumayer, Sabine M.; Ivanov, Ilia N.; Manzo, Michele; Kholkin, Andrei L.; Gallo, Katia; Rodriguez, Brian J.

    2015-12-08

    Controlling ferroelectric switching in Mg doped lithium niobate (Mg: LN) is of fundamental importance for optical device and domain wall electronics applications that require precise domain patterns. Stable ferroelectric switching has been previously observed in undoped LN layers above proton exchanged (PE) phases that exhibit reduced polarization, whereas PE layers have been found to inhibit lateral domain growth. Here, Mg doping, which is known to significantly alter ferroelectric switching properties including coercive field and switching currents, is shown to inhibit domain nucleation and stability in Mg: LN above buried PE phases that allow for precise ferroelectric patterning via domain growth control. Furthermore, piezoresponse force microscopy (PFM) and switching spectroscopy PFM reveal that the voltage at which polarization switches from the "up" to the "down" state increases with increasing thickness in pure Mg: LN, whereas the voltage required for stable back switching to the original "up" state does not exhibit this thickness dependence. This behavior is consistent with the presence of an internal frozen defect field. The inhibition of domain nucleation above PE interfaces, observed in this study, is a phenomenon that occurs in Mg: LN but not in undoped samples and is mainly ascribed to a remaining frozen polarization in the PE phase that opposes polarization reversal. This reduced frozen depolarization field in the PE phase also influences the depolarization field of the Mg: LN layer above due to the presence of uncompensated polarization charge at the PE-Mg: LN boundary. Furthermore, these alterations in internal electric fields within the sample cause long-range lattice distortions in Mg: LN via electromechanical coupling, which were corroborated with complimentary Raman measurements.

  5. Testing the cation-hydration effect on the crystallization of Ca-Mg-CO3 systems.

    PubMed

    Xu, Jie; Yan, Chao; Zhang, Fangfu; Konishi, Hiromi; Xu, Huifang; Teng, H Henry

    2013-10-29

    Dolomite and magnesite are simple anhydrous calcium and/or magnesium carbonate minerals occurring mostly at Earth surfaces. However, laboratory synthesis of neither species at ambient temperature and pressure conditions has been proven practically possible, and the lack of success was assumed to be related to the strong solvation shells of magnesium ions in aqueous media. Here, we report the synthesis of MgCO3 and MgxCa(1-x)CO3 (0 < x < 1) solid phases at ambient conditions in the absence of water. Experiments were carried out in dry organic solvent, and the results showed that, although anhydrous phases were readily precipitated in the water-free environment, the precipitates' crystallinity was highly dependent on the Mg molar percentage content in the solution. In specific, magnesian calcite dominated in low [Mg(2+)]/[Ca(2+)] solutions but gave way to exclusive formation of amorphous MgxCa(1-x)CO3 and MgCO3 in high-[Mg(2+)]/[Ca(2+)] and pure-Mg solutions. At conditions of [Mg(2+)]/[Ca(2+)] = 1, both nanocrystals of Ca-rich protodolomite and amorphous phase of Mg-rich MgxCa(1-x)CO3 were formed. These findings exposed a previously unrecognized intrinsic barrier for Mg(2+) and CO3(2-) to develop long-range orders at ambient conditions and suggested that the long-held belief of cation-hydration inhibition on dolomite and magnesite mineralization needed to be reevaluated. Our study provides significant insight into the long-standing "dolomite problem" in geochemistry and mineralogy and may promote a better understanding of the fundamental chemistry in biomineralization and mineral-carbonation processes.

  6. The Dynamic Range of LZ

    NASA Astrophysics Data System (ADS)

    Yin, Jun; LZ Collaboration

    2015-10-01

    The electronics of the LZ experiment, the 7-ton dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in such a detector, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined by the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines. S2 signals induced by alpha particles from radon decay will saturate one or more channels of the top PMT array but techniques are being developed to recover the information lost due to saturation. This work was supported by the Department of Energy, Grant DE-SC0006605.

  7. Wide Operational Range Thermal Sensor

    NASA Technical Reports Server (NTRS)

    Goebel, John H. (Inventor); McMurray, Robert E., Jr. (Inventor)

    2005-01-01

    Bolometer system and method for detecting, at BLIP levels, presence of radiation over a broad range of wavelengths in an infrared spectrum and in a temperature range from 20 K to as high as room temperature. The radiation is received by a Si crystal having a region that is doped with one or more of In, Ga, S, Se, Te, B, Al, P, As and Sb in a concentration ratio in a range such as 5 x 10(exp -11) to 5 x 10(exp -6). Change in electrical resistance delta R due to receipt of the radiation is measured through a change in voltage difference or current within the crystal, and the quantity delta R is converted to an estimate of the amount of radiation received. Optionally, incident radiation having an energy high enough to promote photoconductivity is removed before detection.

  8. Laser system of extended range

    NASA Technical Reports Server (NTRS)

    Lehr, C. G.

    1972-01-01

    A pulsed laser system was developed for range measurements from the earth to retroreflecting satellites at distances up to that of the moon. The system has a transportable transmitter unit that can be moved from one location to another. This unit consists of a 0.2 m coude refractor and a high radiance, neodymium-glass, frequency doubled laser that operates in a single transverse mode. It can be used for lunar or distant satellite ranging at any observatory that has a telescope with an aperture diameter of about 1.5 m for the detection of the laser return pulses. This telescope is utilized in the same manner customarily employed for the observation of celestial objects. A special photometric package and the associated electronics are provided for laser ranging.

  9. NASA Satellite Laser Ranging Network

    NASA Technical Reports Server (NTRS)

    Carter, David L.

    2004-01-01

    I will be participating in the International Workshop on Laser Ranging. I will be presenting to the International Laser Ranging Service (ILRS) general body meeting on the recent accomplishments and status of the NASA Satellite Laser Ranging (SLR) Network. The recent accomplishments and NASA's future plans will be outlined and the benefits to the scientific community will be addressed. I am member of the ILRS governing board, the Missions working group, and the Networks & Engineering working group. I am the chairman of the Missions Working and will be hosting a meeting during the week of the workshop. I will also represent the NASA SLR program at the ILRS governing board and other working group meetings.

  10. Collision rates for electron excitation of Mg V lines

    NASA Astrophysics Data System (ADS)

    Tayal, S. S.; Sossah, A. M.

    2015-02-01

    Aims: Transition probabilities and electron impact excitation collision strengths and rates for astrophysically important lines in Mg V are reported. The 86 fine-structure levels of the 2s22p4, 2s2p5, 2p6, 2s22p33s, 2s22p33p and 2s22p33d configurations are included in our calculations. The effective collision strengths are presented as a function of electron temperature for solar and other astrophysical applications. Methods: The collision strengths have been calculated using the B-splineBreit-Pauli R-matrixmethod for all fine-structure transitions among the 86 levels. The one-body mass, Darwin and spin-orbit relativistic effects are included in the Breit-Pauli Hamiltonian in the scattering calculations. The one-body and two-body relativistic operators are included in the multiconfiguration Hartree-Fock calculations of transition probabilities. Several sets of non-orthogonal spectroscopic and correlation radial orbitals are used to obtain accurate description of Mg V 86 levels and to represent the scattering functions. Results: The calculated excitation energies are in very good agreement with experiment and represents an improvement over the previous calculations. The present collision strengths show good agreement with the previously available R-matrix and distorted-wave calculations. The oscillator strengths for E1 transitions normally compare very well with previous calculations. The thermally averaged collision strengths are obtained by integrating total resonant and non-resonant collision strengths over a Maxwellian distribution of electron energies and these are presented over the temperature range log 10Te = 3.2-6.0 K. Tables 1-4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/A87

  11. RANGE INCREASER FOR PNEUMATIC GAUGES

    DOEpatents

    Fowler, A.H.; Seaborn, G.B. Jr.

    1960-09-27

    An improved pneumatic gage is offered in which the linear range has been increased without excessive air consumption. This has been accomplished by providing an expansible antechamber connected to the nozzle of the gage so that the position of the nozzle with respect to the workpiece is varied automatically by variation in pressure within the antechamber. This arrangement ensures that the nozzle-to-workpiece clearance is maintained within certain limits, thus obtaining a linear relation of air flow to nozzle-to-workpiece clearance over a wider range.

  12. GEA CRDA Range Data Analysis

    DTIC Science & Technology

    1999-07-28

    E1, July-August 1998 18 3.3. Example 3: SatMex, Solidaridad 2, May-June 1998 27 3.4. Example 4: PanAmSat, Galaxy IV, May-June 1998 33 3.5...17 Millstone measurements residuals for Telstar 401 on Days 181-263. 26 3-18 Millstone measurement residuals for Solidaridad 1 on Days 141-153...with 29 SatMex range data. 3-19 Hermosillo B-- Solidaridad 1 range residuals through Days 135-144 with bias 30 removed. 3-20 Iztapalapa D

  13. Radio pill antenna range test

    NASA Astrophysics Data System (ADS)

    Cummins, W. F.; Kane, R. J.

    1992-05-01

    In order to investigate the potential of a proposed 'radio pill' beacon transmitter, a range test experiment was devised and carried out in the VHF frequency range. Calculations and previous work indicated that optimum sensitivity and, thus, distance would be obtained in this frequency range provided body radio-frequency (RF) absorption was not too great. A ferrite-core loop antenna is compatible with a pill geometry and has better radiation efficiency than an air core loop. The ferrite core may be a hollow cylinder with the electronics and batteries placed inside. However, this range test was only concerned with experimentally developing test range data on the ferrite core antenna itself. A one turn strap loop was placed around a 9.5 mm diameter by 18.3 mm long stack of ferrite cores. This was coupled to a 50 Omega transmission line by 76 mm of twisted pair line and a capacitive matching section. This assembly was excited by a signal generator at output levels of -10 to +10 dBm. Signals were received on a VHF receiver and tape recorder coupled to a 14 element, circularly polarized Yagi antenna at a height of 2.5 m. Field strength measurements taken at ranges of 440, 1100, and 1714 m. Maximum field strengths referenced to 0 dBm transmitter level were -107 to -110 dB at 440 m, -124 to -127 dBm at 1100 m, and -116 to -119 dBm at 1714 m when the antenna cylinder was horizontal. Field strengths with a vertical antenna were about 6 dB below these values. The latter transmit site was elevated and had a clear line-of-site path to the receiving site. The performance of this test antenna was better than that expected from method-of-moment field calculations. When this performance data is scaled to a narrow bandwidth receiving system, ground level receiving ranges of a few to 10 km can be expected. Clear line-of-sight ranges where either or both the transmitter and receiver are elevated could vary from several km to 100 km.

  14. A Hot Gaseous Galaxy Halo Candidate with Mg X Absorption

    NASA Astrophysics Data System (ADS)

    Qu, Zhijie; Bregman, Joel N.

    2016-12-01

    The hot gas in galaxy halos may account for a significant fraction of missing baryons in galaxies, and some of these gases can be traced by high ionization absorption systems in QSO UV spectra. Using high S/N Hubble Space Telescope/Cosmic Origins Spectrograph spectra, we discovered a high ionization state system at z = 1.1912 in the sightline toward LBQS 1435-0134, and two-component absorption lines are matched for Mg x, Ne viii, Ne vi, O vi, Ne v, O v, Ne iv, O iv, N iv, O iii, and H i. Mg x, detected for the first time (5.8σ), is a particularly direct tracer of hot galactic halos, as its peak ion fraction occurs near 106.1 K, about the temperature of a virialized hot galaxy halo of mass ˜ 0.5{M}* . With Mg x and Ne viii, a photoionization model cannot reproduce the observed column densities with path lengths of galaxy halos. For collisional ionization models, one or two-temperature models do not produce acceptable fits, but a three-temperature model or a power-law model can produce the observed results. In the power-law model, {dN}/{dT}={10}4.4+/- 2.2-[Z/X]{T}1.55+/- 0.41 with temperatures in the range of {10}4.39+/- 0.13 {{K}}\\lt T\\lt {10}6.04+/- 0.05 {{K}}, the total hydrogen column density is 8.2× {10}19(0.3 {Z}⊙ /Z) {{cm}}-2 and the positive power-law index indicates most of the mass is at the high temperature end. We suggest that this absorption system is a hot volume-filled galaxy halo rather than interaction layers between the hot halo and cool clouds. The temperature dependence of the column density is likely due to the local mixture of multiple phase gases.

  15. Grain Boundary Diffusion of Sulfur in MgO

    NASA Astrophysics Data System (ADS)

    Watson, H. C.; Watson, E. B.

    2013-12-01

    From being a candidate light element in the Earth's core to recording biosignatures on the surface, sulfur is a minor, but critical, element throughout the Earth. A deeper understanding the behaviour of sulfur under a wide scope of Earth relevant conditions will provide insight into geochemical cycles and reservoirs from the crust to the core. Sulfur isotope ratios in particular may be used to record specific geochemical processes such as ongoing core/mantle interaction, as well as shallower processes including cycling between the atmosphere/hydrosphere and lithosphere. The mobility of sulfur under these conditions will affect the reliability of using observed signatures to distinguish past processes and events. Grain boundary diffusion has often been shown to be orders of magnitude more rapid than diffusion through the crystal lattice of many materials. This effect is particularly important in cases where the diffusant is incompatible in the crystal lattice, and thus resides predominantly on grain boundaries. This is the case for sulfur and many of the minerals that comprise the interior of the Earth. If S diffusion is fast enough, the retention of some pristine signatures could be compromised. In other cases fast diffusion may allow for detection of signatures at large distances from their original source, as suggested by [1]. Experiments have been conducted in a piston-cylinder device at 1GPa and temperatures ranging from 1100°C to 1500°C to determine the rate of S grain boundary diffusion in an MgO matrix. A source-sink method similar to that used by [1] was employed using either FeS or FeS2 as a source and Mo foil as a sink separated by up to 3mm of pure MgO polycrystalline matrix. The foil sink was analyzed by electron microprobe and laser ablation ICP-MS for S content. Preliminary results show substantial diffusion of S through the MgO matrix. The results from these experiments, potential applications, and relevant numerical simulations will be presented

  16. Hydrogen Incorporation in Aluminous MgSiO3-Perovskite

    NASA Astrophysics Data System (ADS)

    Smyth, J. R.; Jacobsen, S. D.; Huss, G. R.; Miyajima, N.; Pamato, M. G.

    2013-12-01

    We have synthesized hydrous, aluminum-bearing MgSiO3 perovskite samples at 25GPa and various temperatures from 1600 to 2200C in a multi-anvil press and have characterized the samples by single-crystal X-ray diffraction, Raman spectroscopy, electron microprobe (EPMA), transmission electron microscopy (TEM), and secondary ion mass spectroscopy (SIMS). Perovskite crystals range up to 100 micrometers in size and contain 1 - 2.5% by weight Al2O3. SIMS analyses with a probe spot of approximately 10 micron square indicate up to several thousand ppm by weight H2O which corresponds to one H per Al atom in the structure. Microprobe chemical analysis and crystal structure refinement from single crystal X-ray data indicates that Al substitutes in the Si site, but not in the Mg site. However, Raman spectroscopy indicates the presence of micro-inclusions of brucite, super-hydrous phase B (SHyB), magnesite, and stishovite in most samples. Some of the perovskite crystals in the samples synthesized at temperatures above 2100 C exhibit rounded inclusions that are interpreted to be melt that quenched to perovskite plus brucite, phase D, and/or stishovite. Nearly all spectra show O-H stretching bands that are associated with brucite and/or Shy-B. None of the samples show a Raman peak in the O-H stretching region (3000 to 3700 cm-1) that correlates in intensity with perovskite Raman lattice modes. Our provisional interpretation is that the MgSiO3-perovskite structure incorporates very little H2O (<100 ppmw) and that most of the H in the samples is contained in brucite, phase D, superhydrous phase B (SHyB) or aluminous stishovite. This implies that the magnesium silicate perovskite phase in the lower mantle is unlikely to be a significant host for H in the lower mantle. However, phase D may be stabilized to higher temperatures by incorporation of Al and is extremely hydrous so that two modal percent of phase D may allow the lower mantle to contain several thousand ppmw H2O. Such a small

  17. Main reinforcement effects of precipitation phase Mg2Cu3Si, Mg2Si and MgCu2 on Mg-Cu-Si alloys by ab initio investigation

    NASA Astrophysics Data System (ADS)

    Shi, Xue-Feng; Wang, Hai-Chen; Tang, Ping-Ying; Tang, Bi-Yu

    2017-09-01

    To predict and compare the main reinforcement effects of the key precipitation phases Mg2Cu3Si, Mg2Si and MgCu2 in Mg-Cu-Si alloy, the structural, mechanical and electronic properties of these phases have been studied by ab initio calculations. The lowest formation enthalpy and cohesive energy indicate that Mg2Cu3Si has the strongest alloying ability and structural stability. The mechanical modulus indicates that Mg2Cu3Si has the strongest resistance to reversible shear/volume distortion and has maximum hardness. The characterization of brittle (ductile) behavior manifests that MgCu2 has favorable ductility. Meanwhile the evaluation of elastic anisotropy indicates that Mg2Si possesses elastic isotropy. Debye temperature prediction shows that Mg2Si and Mg2Cu3Si have better thermal stability. To achieve an unbiased interpretation on the phase stability and mechanical behavior of these precipitation phases, the density of states and differential charge densities are also analyzed. The current study deepens the comprehensive understanding of main reinforcement effects of these precipitation phases on Mg-Cu-Si alloys, and also benefits to optimize the overall performances of Mg-Cu-Si alloy from the hardness, ductility and thermal stability by controlling these second precipitation phases during the heat treatment process.

  18. Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys

    NASA Astrophysics Data System (ADS)

    Urgnani, J.; Di Chio, M.; Palumbo, M.; Feuerbacher, M.; Fernandez, J. F.; Leardini, F.; Baricco, M.

    2009-01-01

    The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H2 absorption/desorption kinetics. In this paper, the interaction of H2 with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg38.5Al61.5, Mg69Al31 and Mg72Al28. For Mg72Al28, no significant changes in the microstructure have been obtained by rapid solidification. In Mg69Al31, a significant grain refinement has been observed, whereas, for Mg38.5Al61.5, the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H2 absorption, leading to MgH2. After heating up to 430 °C the hydrogenated samples, a main desorption reaction from MgH2 has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.

  19. Optical and electrical properties of Mg-doped AlN nanowires grown by molecular beam epitaxy

    SciTech Connect

    Connie, Ashfiqua Tahseen; Zhao, Songrui; Sadaf, Sharif Md.; Shih, Ishiang; Mi, Zetian; Du, Xiaozhang; Lin, Jingyu; Jiang, Hongxing

    2015-05-25

    In this paper, the optical and electrical properties of Mg-doped AlN nanowires are discussed. At room temperature, with the increase of Mg-doping concentration, the Mg-acceptor energy level related optical transition can be clearly measured, which is separated about 0.6 eV from the band-edge transition, consistent with the Mg activation energy in AlN. The electrical conduction measurements indicate an activation energy of 23 meV at 300 K–450 K temperature range, which is significantly smaller than the Mg-ionization energy in AlN, suggesting the p-type conduction being mostly related to hopping conduction. The free hole concentration of AlN:Mg nanowires is estimated to be on the order of 10{sup 16 }cm{sup −3}, or higher.

  20. Cardiovascular effect of dental anesthesia with articaine (40 mg with epinefrine 0,5 mg % and 40 mg with epinefrine 1 mg%) versus mepivacaine (30 mg and 20 mg with epinefrine 1 mg%) in medically compromised cardiac patients: a cross-over, randomized, single blinded study.

    PubMed

    Torres-Lagares, Daniel; Serrera-Figallo, María-Ángeles; Machuca-Portillo, Guillermo; Corcuera-Flores, José-Ramón; Machuca-Portillo, Carmen; Castillo-Oyagüe, Raquel; Gutiérrez-Pérez, José-Luis

    2012-07-01

    The aim of the present study is to compare cardiovascular safety profiles of two dental anesthetics: articaine versus two standard mepivacaine solutions used during etiological periodontal treatment in cardiovascular patients. Using a cross-over study design, ten cardiovascular patients were randomly assigned to dental treatment with 1.8 mL of a local anesthetic injected on each quadrant of the mouth: Articaine (40 mg with Epinephrine 0.5 mg % and 40 mg with Epinephrine 1mg %) or Mepivacaine (30 mg and 20 mg with Epinephrine 1mg %). A computer programme enabled continuous longitudinal data collection: O2 saturation, blood pressure (BP) and heart rate (HR). No severe clinical side effects were observed. During the treatment period, we observed statistically significant differences as regards HR between injections with and without adrenalin (p< 0.039) and as regards systolic (p< 0.046) and diastolic (p < 0.046) blood pressure during the stabilization period. In both cases, the parameters under study increase. Age, gender, jaw treated, treatment duration and the rest of cardiovascular variables did not affect the results. None of the patients underwent ischemic alterations or any other complication derived from the treatment or the anesthesia. According to the results of our study, dental anesthetics with standard concentrations of Epinephrine seem to alter HR and BP. Although no cardiac ischemic alterations or any other cardiovascular complications have been observed, we must be cautious with the administration of anesthetics containing vasoconstrictors in patients with cardiovascular diseases.