Sample records for manganese non-magnetic steel

  1. Manganese.

    PubMed

    Barceloux, D G

    1999-01-01

    Manganese is a very hard, brittle metal, which is used to increase the strength of steel alloys. Absorption from the gastrointestinal tract occurs in the divalent and tetravalent forms. Permanganates, which are strong oxidizing agents, have a +7 valence. The principal organomanganese compound is the anti-knock additive, methylcyclopentadienyl manganese tricarbonyl. Manganese is a ubiquitous constituent of the environment comprising about 0.1% of the earth's crust. For the general population, food is the most important source of manganese with daily intake ranging from 2-9 mg Mn. Combustion of gasoline containing methylcyclopentadienyl manganese tricarbonyl releases submicron particles of Mn3O4 that are potentially respirable. Biomagnification of manganese in the food chain probably does not occur. The lungs and gastrointestinal tract absorb some manganese, but the relative amounts absorbed from each site are not known. Homeostatic mechanisms limit the absorption of manganese from the gastrointestinal tract. Elimination of manganese occurs primarily by excretion into the bile. Animal studies indicate that manganese is an essential co-factor for enzymes, such as hexokinase, superoxide dismutase, and xanthine oxidase. However, no case of manganese deficiency in humans has been identified. Manganism is a central nervous system disease first described in the 1800s following exposure to high concentrations of manganese oxides. Manganese madness was the term used to describe the initial psychiatric syndrome (compulsive behavior, emotional lability, hallucinations). More commonly, these workers developed a Parkinson's-like syndrome. Currently, the risks of exposure to low concentrations of manganese in the industrial and in the environmental settings (e.g., methylcyclopentadienyl manganese tricarbonyl in gasoline) are being evaluated with regards to the development of subclinical neuropsychological changes. The American Conference of Governmental and Industrial Hygienists recently lowered the TLV-TWA for manganese compounds and inorganic manganese compounds to 0.2 mg Mn/m3. PMID:10382563

  2. Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.

    PubMed

    Xu, Jing-Cheng; Chen, Gu; Huang, Xiang-Feng; Li, Guang-Ming; Liu, Jia; Yang, Na; Gao, Sai-Nan

    2009-09-30

    To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes. PMID:19443107

  3. Substitution of manganese and nitrogen for nickel in stainless steels

    Microsoft Academic Search

    A. A. Babakov

    1961-01-01

    1.Added nitrogen promotes the formation of austenite in chrome-nickel stainless steels of the austenite class.2.In order to keep the nitrogen in the steel, attempts must be made to form stable nitrides with a high dissociation point. Among such nitrides are chromium nitrides. It has been found that manganese has a positive effect and improves the solubility of nitrogen in steel.3.Nitrogen

  4. Critical Aspects of Alloying of Sintered Steels with Manganese

    NASA Astrophysics Data System (ADS)

    Hryha, Eduard; Dudrova, Eva; Nyborg, Lars

    2010-11-01

    This study examines the sintering behavior and properties of Fe-0.8Mn-0.5C manganese powder metallurgy steels. The study focuses on the influence of mode of alloying—admixing using either high-purity electrolytic manganese or medium carbon ferromanganese as well as the fully prealloying of water-atomized powder. Three main aspects were studied during the whole sintering process—microstructure development, interparticle necks evolution, and changes in the behavior of manganese carrier particles during both heating and sintering stages. The prealloyed powder shows considerable improvement in carbon homogenization and interparticle neck development in comparison with admixed materials. The first indication of pearlite for the fully prealloyed material was registered at ~1013 K (740 °C) in comparison with ~1098 K (825 °C) in the case of the admixed systems. The negative effect of the oxidized residuals of manganese carrier particles and high microstructure inhomogeneity, which is a characteristic feature of admixed systems, is reflected in the lower values of the mechanical properties. The worst results in this respect were obtained for the system admixed with electrolytic manganese because of more intensive manganese sublimation and resulting oxidation at lower temperatures. According to the results of X-ray photoelectron spectroscopy and high-resolution scanning electron microscopy and energy dispersive X-ray analyses, the observed high brittleness of admixed materials is connected with intergranular decohesion failure associated with manganese oxide formation on the grain boundaries.

  5. Deformation and fracture behaviour of high manganese austenitic steel

    Microsoft Academic Search

    Emin Bayraktar; Fazal A Khalid; Christophe Levaillant

    2004-01-01

    In this work, the deformation behaviour of high manganese austenitic Hadfield steel sheet samples was studied under uniaxial tensile test conditions. The tests were performed at various strain rates and temperatures to examine the effect of strain rate and microhardness on the strain hardening and formability of sheet samples for production of bullet-proof helmets. The effect of temperature on the

  6. Mechanical behaviour of a new automotive high manganese TWIP steel in the presence

    E-print Network

    Paris-Sud XI, Université de

    , as austenitic steels, they appear to be sensitive to liquid zinc embrittlement during welding, the liquid zinc to suggest solutions for preventing cracking during spot welding of such steels. Keywords: TWIP steels - HighAnnée 2011 Thèse Mechanical behaviour of a new automotive high manganese TWIP steel in the presence

  7. Stacking fault energy and plastic deformation of fully austenitic high manganese steels: Effect of Al addition

    Microsoft Academic Search

    Kyung-Tae Park; Kwang Geun Jin; Sang Ho Han; Si Woo Hwang; Kayoung Choi; Chong Soo Lee

    2010-01-01

    Dependence of the dislocation glide mode and mechanical twinning on the stacking fault energy (SFE) in fully austenitic high manganese steels was investigated. Fully austenitic Fe–22Mn–xAl–0.6C (x=0, 3, and 6) steels with the SFE in the range of 20–50mJ\\/m2 were tensile tested at room temperature, and their deformed microstructures were examined at the different strain levels by optical microscopy and

  8. Microstructural characterization of high-manganese austenitic steels with different stacking fault energies

    Microsoft Academic Search

    Shigeo Sato; Eui-Pyo Kwon; Muneyuki Imafuku; Kazuaki Wagatsuma; Shigeru Suzuki

    2011-01-01

    Microstructures of tensile-deformed high-manganese austenitic steels exhibiting twinning-induced plasticity were analyzed by electron backscatter diffraction pattern observation and X-ray diffraction measurement to examine the influence of differences in their stacking fault energies on twinning activity during deformation. The steel specimen with the low stacking fault energy of 15mJ\\/m2 had a microstructure with a high population of mechanical twins than the

  9. Cryogenic mechanical properties of heavy-section weldment in high-manganese austenitic steel

    Microsoft Academic Search

    O. Matsumoto; T. Tsuchiyama; S. Hada

    1997-01-01

    Cryogenic mechanical properties of a heavy-section weldment of high-manganese austenitic steel for the structure of superconducting magnet were evaluated, The heavy-section weld joint with a 200 mm thickness was manufactured by gas tungsten arc welding (GTAW) process using 21Mn-13Cr-5Ni-0.2N-B steel weld material. No cracks were observed in the weld metal. Tensile property and fracture toughness were tested at 4 K.

  10. Effect of manganese and nitrogen on the solidification mode in austenitic stainless steel welds

    NASA Astrophysics Data System (ADS)

    Suutala, N.

    1982-12-01

    The macrostructures and microstructures of thirty different austenitic stainless welds alloyed with manganese and Jor nitrogen are analyzed. Comparison of the results with those obtained from normal welds of the AISIJAWS 300 series indicates that the solidification mode and Ferrite Number can be predicted adequately using chromium and nickel equivalents. The solidification mode in the normal and nitrogen-alloyed welds can be best described by the equivalents developed by Hammar and Svensson and the Ferrite Number by the conventional Schaeffler-DeLong diagram. Both of these descriptions are invalid at high manganese content values (5 to 8 pct), however, in which case Hull’s equivalents give a better correlation between the composition and the solidification mode or Ferrite Number. The complicated role of manganese and the austenite-favoring effect of nitrogen in austenitic stainless steels are discussed.

  11. Corrosion of stainless steel piping in a high manganese fresh water

    SciTech Connect

    Avery, R.E. [Nickel Development Inst., Londonderry, NH (United States); Lutey, R.W. [Buckman Labs., Memphis, TN (United States); Musick, J. [Whitman and Howard, Portland, ME (United States); Pinnow, K.E. [Crucible Research, Pittsburgh, PA (United States); Tuthill, A.H. [Nickel Development Inst., Blacksburg, VA (United States)

    1996-07-01

    In March of 1993, about two years after startup in early 1991, pinhole leaks were found in the 16 in. (406 mm) type 304L stainless steel (UNS S30403) raw water piping at the Brunswick-Topsham Water District (BTWD) Potable Water Treatment Plant (PWTP) in Brunswick, Maine. The low chloride manganese-containing well water is chlorinated in the pump house. After reaching the plant, the raw water is handled in type 304L stainless steel (UNS S30403) piping. It was initially felt that the corrosion might be the microbiologically influenced corrosion (MIC) type corrosion described by Tverberg, Pinnow, and Redmerski. Investigation showed that the role of manganese and chlorine differed, in important respects, from that described by Tverberg et. al., and that heat tint scale may have played a significant role in the corrosion that occurred at the BTWD plant.

  12. Manganese

    MedlinePLUS

    ... no RDAs for a nutrient, the Adequate Intake (AI) is used as a guide. The AI is the estimated amount of the nutrient that ... assumed to be adequate. The daily Adequate Intake (AI) levels for manganese are: infants birth to 6 ...

  13. Stress-deformation behaviour of high manganese (AI, Si) TRIP and TWIP steels

    NASA Astrophysics Data System (ADS)

    Krüger, L.; Meyer, L. W.; Brûx, U.; Frommeyer, G.; Grässel, O.

    2003-09-01

    Microstructure and mechanical properties of high manganese (Al, Si) TRIP (transformation induced plasticity) and TWIP (twinning induced plasticity) steels were investigated at quasistatic and dynamic tensile loading in a wide range of temperature. The mechanical properties are strongly dependent on the stacking fault energy and are influenced by chemical composition, temperature and loading rates. A gradual formation of deformation twins and/or martensitic phase transformation are essential to achieve excellent formability at high strength levels.

  14. Plastic anisotropy of low-carbon, low-manganese steels containing niobium

    Microsoft Academic Search

    P. R. Mould; J. M. Gray

    1972-01-01

    The effect of niobium additions (up to 0.23 pct) on the plastic anisotropy of cold-rolled and annealed low-carbon, low-manganese steels has been studied. When hot-rolling conditions involving coiling temperatures below 1150°F were used, increased concentrations of niobium were deleterious to the development of high plastic anisotropy. Isothermal transformation studies and special hot-rolling studies showed that when transformation from austenite to

  15. Plastic anisotropy of low-carbon, low-manganese steels containing niobium

    Microsoft Academic Search

    P. R. Mould; J. M. Gray

    1972-01-01

    The effect of niobium additions (up to 0.23 pct) on the plastic anisotropy of cold-rolled and annealed low-carbon, low-manganese\\u000a steels has been studied. When hot-rolling conditions involving coiling temperatures below 1150F were used, increased concentrations\\u000a of niobium were deleterious to the development of high plastic anisotropy. Isothermal transformation studies and special hot-rolling\\u000a studies showed that when transformation from austenite to

  16. Manganese-stabilized austenitic stainless steels for fusion applications

    DOEpatents

    Klueh, Ronald L. (Knoxville, TN); Maziasz, Philip J. (Oak Ridge, TN)

    1990-01-01

    An austenitic stainless steel that is comprised of Fe, Cr, Mn, C but no Ni or Nb and minimum N. To enhance strength and fabricability minor alloying additions of Ti, W, V, B and P are made. The resulting alloy is one that can be used in fusion reactor environments because the half-lives of the elements are sufficiently short to allow for handling and disposal.

  17. Improvement of high temperature strength and low temperature toughness of high manganese-chromium austenitic steels

    NASA Astrophysics Data System (ADS)

    Miyahara, Kazuya; Bae, Dong-Su; Shimoide, Yukio

    1994-09-01

    High Mn-Cr austenitic steels are still considered to be an important high temperature structural material from the point of view of fast-induced radioactivity decay (FIRD) and non-magneticity. The objective of the present study is to investigate the mechanical properties of 12% Cr-15% Mn austenitic stainless steels and to compare these properties with those of the reference materials of JPCAs and JFMS, which are being investigated for the development of fusion reactor structural materials in Japan. The effects of the alloying elements V, Ti, Ta, etc. were investigated to determine the improvement of mechanical properties. Tiny precipitates of VN and Ti(C, N) raised the high-temperature strength considerably. Content of 0.1 to 0.2% C, however, formed very coarse precipitates of M 23C 6 type carbide on the grain boundaries, which deteriorated low temperature toughness inducing intergranular fracture. Microstructural evolution during long-term aging was also investigated.

  18. Manganese and nitrogen in stainless steel SMA welds for cryogenic service

    SciTech Connect

    Mc Cowan, C.N.; Siewart, T.A.; Reed, R.P.; Lake, F.B.

    1987-03-01

    Evaluation of a shielded metal arc (SMA) weld test matrix in which manganese (1.5 to 10 wt-%) and nitrogen (0.04 to 0.26wt-%) were varied independently has clarified the effect of these elements on cryogenic mechanical properties and predicted ferrite number (FN). Several molybdenum and boron additions were also made, but they had no observable effect on strength or Charpy V-notch (CVN) absorbed energy. The matrix was based on a type 308L stainless steel weld metal composition. Desired compositions and constant FN were attained through alloy additions to the electrode coating. For each weld, one all-weld metal 4-K tensile specimen and five 76-K CVN impact specimens were tested. Increasing the nitrogen content from 0.05 to 0.25 wt-% linearly increased the 4-K yield strength from 600 to 1300 MPa (87 to 188.5 ksi) and decreased the 76-K lateral expansion from 0.6 to 0.1 mm (0.24 to 0.04 in.). Nitrogen reduced the 76-K CVN absorbed energy but not linearly. The addition of manganese slightly increased the yield strength and slightly decreased the lateral expansion. The 4-K tensile strength was relatively unaffected by alloy additions; values varied between 1300 and 1500 MPa (188.5 and 217.5 ksi). The DeLong FN predictive equation was improved by substituting the Szumachowski-Kotecki constant manganese term of 0.35 into the DeLong nickel equivalent. Analysis of the remaining FN deviation revealed an interaction between nitrogen and manganese. Addition of manganese-nitrogen interactive terms to the nickel equivalent increased the accuracy of the FN prediction.

  19. Effects of Manganese Content on Solidification Structures, Thermal Properties, and Phase Transformation Characteristics in Fe-Mn-C Steels

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Wang, Yu-Nan; Ruan, Xiao-Ming; Wang, Rui-Zhi; Zhu, Kai; Fan, Zheng-Jie; Wang, Ying-Chun; Li, Cheng-Bin; Jiang, Xiao-Fang

    2015-02-01

    The solidification structures and the thermal properties of Fe-Mn-C steel ingots containing different manganese contents have been investigated and the phase transformation characteristics have been revealed by Thermo-Calc to assist development of the continuous casting technology of Fe-Mn-C steels. The results show that the thermal conductivity of the 0Mn steel is higher than that of the 3Mn steel. The thermal conductivity of the 6Mn steel is the lowest in the three kinds of steels below 1023 K (750 °C) and the highest above 1173 K (900 °C). The 0Mn steel has the highest value of the proportion of equiaxed grain zone area in the three kinds of steels, whereas the 3Mn steel has the lowest value of it in the steels. Manganese has the effect of promoting the coarsening of grains. The microstructure is martensite and a little retained austenite (3.8 mass pct) in the 6Mn steel, whereas the microstructure is bainite in the 3Mn steel. The 0Mn steel is characterized by ferrite and pearlite. The mean thermal expansion coefficients of the steels are in the range from 1.0 × 10-5 to 1.6 × 10-5 K-1, and the determinations of mold tapers of the 6Mn and 3Mn steels can refer to low-carbon steel. Using RA <60 pct as the criterion, the third brittle temperature region of the 6Mn steel is 873 K to 1073 K (600 °C to 800 °C), whereas those of the 3Mn steel and the 0Mn steel are 873 K to 1123 K (600 °C to 850 °C) and 873 K to 1173 K (600 °C to 900 °C), respectively. In the 6Mn and 3Mn steels, the deformation-induced ferrite (DIF) forms in sufficient quantities cause the recovery of the ductility at the low temperature end. However, since low strains are present when straightening, sufficient quantities of DIF cannot be formed. Thus, the ductility of the 6Mn and 3Mn steels cannot be improved during the continuous casting process. Manganese has the effect of enlarging the austenite phase region and reducing the ?-ferrite phase region and ?-ferrite phase region.

  20. Transformation Characteristics of Ferrite/Carbide Aggregate in Continuously Cooled, Low Carbon-Manganese Steels

    NASA Astrophysics Data System (ADS)

    Di Martino, S. F.; Thewlis, G.

    2014-02-01

    Transformation characteristics and morphological features of ferrite/carbide aggregate (FCA) in low carbon-manganese steels have been investigated. Work shows that FCA has neither the lamellae structure of pearlite nor the lath structure of bainite and martensite. It consists of a fine dispersion of cementite particles in a smooth ferrite matrix. Carbide morphologies range from arrays of globular particles or short fibers to extended, branched, and densely interconnected fibers. Work demonstrates that FCA forms over similar cooling rate ranges to Widmanstätten ferrite. Rapid transformation of both phases occurs at temperatures between 798 K and 973 K (525 °C and 700 °C). FCA reaction is not simultaneous with Widmanstätten ferrite but occurs at temperatures intermediate between Widmanstätten ferrite and bainite. Austenite carbon content calculations verify that cementite precipitation is thermodynamically possible at FCA reaction temperatures without bainite formation. The pattern of precipitation is confirmed to be discontinuous. CCT diagrams have been constructed that incorporate FCA. At low steel manganese content, Widmanstätten ferrite and bainite bay sizes are significantly reduced so that large amounts of FCA are formed over a wide range of cooling rates.

  1. Diffusion zone between high-chromium cast iron and high-manganese steel during electric-slag facing

    SciTech Connect

    Ponomarenko, V.P.; Shvartser, A.Y.; Stroganova, G.V.

    1986-05-01

    The authors investigate extending the service lives of components by the method of electric-slag facing of working surfaces. Steel 45 was used in the annealed state. Electric-slag remelting was the method used to determine the bending strength. Metallographic examinations were conducted under an MIM-8m microscope, while x-ray analysis of the built-up and base metals were performed on a DRON-2 diffractometer. BAsic alloying elements, chromium and manganese were studied on a ''Cameca MS-46'' microanalyzer. During the electri-slag facing of a high-chromium cast iron containing 8% of Mn on high-manganese steel 11OG13L diffusion equalization of the manganese content occurs in the fusion zone. Diffusion displacement of carbon, chromium, and manganese from high-chromium cast iron into the high-manganese steel during electric-slag facing gies rise to a smooth change in the structure of the metal in the fusion zone, and to increased strength of the joint between the unlike materials investigated.

  2. Grain refinement of a nickel and manganese free austenitic stainless steel produced by pressurized solution nitriding

    SciTech Connect

    Mohammadzadeh, Roghayeh, E-mail: r_mohammadzadeh@sut.ac.ir; Akbari, Alireza, E-mail: akbari@sut.ac.ir

    2014-07-01

    Prolonged exposure at high temperatures during solution nitriding induces grain coarsening which deteriorates the mechanical properties of high nitrogen austenitic stainless steels. In this study, grain refinement of nickel and manganese free Fe–22.75Cr–2.42Mo–1.17N high nitrogen austenitic stainless steel plates was investigated via a two-stage heat treatment procedure. Initially, the coarse-grained austenitic stainless steel samples were subjected to an isothermal heating at 700 °C to be decomposed into the ferrite + Cr{sub 2}N eutectoid structure and then re-austenitized at 1200 °C followed by water quenching. Microstructure and hardness of samples were characterized using X-ray diffraction, optical and scanning electron microscopy, and micro-hardness testing. The results showed that the as-solution-nitrided steel decomposes non-uniformly to the colonies of ferrite and Cr{sub 2}N nitrides with strip like morphology after isothermal heat treatment at 700 °C. Additionally, the complete dissolution of the Cr{sub 2}N precipitates located in the sample edges during re-austenitizing requires longer times than 1 h. In order to avoid this problem an intermediate nitrogen homogenizing heat treatment cycle at 1200 °C for 10 h was applied before grain refinement process. As a result, the initial austenite was uniformly decomposed during the first stage, and a fine grained austenitic structure with average grain size of about 20 ?m was successfully obtained by re-austenitizing for 10 min. - Highlights: • Successful grain refinement of Fe–22.75Cr–2.42Mo–1.17N steel by heat treatment • Using the ? ? ? + Cr{sub 2}N reaction for grain refinement of a Ni and Mn free HNASS • Obtaining a single phase austenitic structure with average grain size of ? 20 ?m • Incomplete dissolution of Cr{sub 2}N during re-austenitizing at 1200 °C for long times • Reducing re-austenitizing time by homogenizing treatment before grain refinement.

  3. Influence of explosive density on mechanical properties of high manganese steel explosion hardened

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoyan; Shen, Zhaowu; Liu, Yingbin; Liu, Tiansheng; Wang, Fengying

    2013-12-01

    The explosion hardening tests of high manganese steel were carried out by using two kinds of explosives of the same composition but different density, respectively. The detonation velocities were tested and the relevant mechanical properties were studied. The results show that the stronger single impulse acting on the specimen, the more hardness of surface increases and the more impact toughness decreases. Compared with the explosive of 1.48 g/cm3 density, the hardness, elongation rate, and impact toughness of the sample for triple explosion with explosive of 1.38 g/cm3 density are larger at the same hardening depth. In addition, the tensile strength of the sample for triple explosion with density of 1.38 g/cm3 is higher from the surface to 15 mm below the surface hardened.

  4. Microstructural characterization of high-manganese austenitic steels with different stacking fault energies

    SciTech Connect

    Sato, Shigeo, E-mail: s.sato@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Kwon, Eui-Pyo [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Imafuku, Muneyuki [Faculty of Engineering, Tokyo City University, Tokyo 158-8557 (Japan); Wagatsuma, Kazuaki [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Suzuki, Shigeru [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2011-08-15

    Microstructures of tensile-deformed high-manganese austenitic steels exhibiting twinning-induced plasticity were analyzed by electron backscatter diffraction pattern observation and X-ray diffraction measurement to examine the influence of differences in their stacking fault energies on twinning activity during deformation. The steel specimen with the low stacking fault energy of 15 mJ/m{sup 2} had a microstructure with a high population of mechanical twins than the steel specimen with the high stacking fault energy (25 mJ/m{sup 2}). The <111> and <100> fibers developed along the tensile axis, and mechanical twinning occurred preferentially in the <111> fiber. The Schmid factors for slip and twinning deformations can explain the origin of higher twinning activity in the <111> fiber. However, the high stacking fault energy suppresses the twinning activity even in the <111> fiber. A line profile analysis based on the X-ray diffraction data revealed the relationship between the characteristics of the deformed microstructures and the stacking fault energies of the steel specimens. Although the variation in dislocation density with the tensile deformation is not affected by the stacking fault energies, the effect of the stacking fault energies on the crystallite size refinement becomes significant with a decrease in the stacking fault energies. Moreover, the stacking fault probability, which was estimated from a peak-shift analysis of the 111 and 200 diffractions, was high for the specimen with low stacking fault energy. Regardless of the difference in the stacking fault energies of the steel specimens, the refined crystallite size has a certain correlation with the stacking fault probability, indicating that whether the deformation-induced crystallite-size refinement occurs depends directly on the stacking fault probability rather than on the stacking fault energies in the present steel specimens. - Highlights: {yields} We studied effects of stacking fault energies on deformed microstructures of steels. {yields} Correlations between texture and occurrence of mechanical twinning are discussed. {yields} Evolutions of dislocations and crystallite are analyzed by line profile analysis.

  5. Structure analysis of aluminium silicon manganese nitride precipitates formed in grain-oriented electrical steels

    SciTech Connect

    Bernier, Nicolas, E-mail: n.bernier@yahoo.fr [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Xhoffer, Chris [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Van De Putte, Tom, E-mail: tom.vandeputte@arcelormittal.com [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Galceran, Montserrat [Université Libre de Bruxelles, 4MAT (Materials Engineering, Characterization, Synthesis and Recycling), Avenue F.D. Roosevelt 50, 1050 Brussels (Belgium); CIC Energigune, Albert Einstein 48, 01510 Miñano (Álava) (Spain); Godet, Stéphane [Université Libre de Bruxelles, 4MAT (Materials Engineering, Characterization, Synthesis and Recycling), Avenue F.D. Roosevelt 50, 1050 Brussels (Belgium)

    2013-12-15

    We report a detailed structural and chemical characterisation of aluminium silicon manganese nitrides that act as grain growth inhibitors in industrially processed grain-oriented (GO) electrical steels. The compounds are characterised using energy dispersive X-ray spectrometry (EDX) and energy filtered transmission electron microscopy (EFTEM), while their crystal structures are analysed using X-ray diffraction (XRD) and TEM in electron diffraction (ED), dark-field, high-resolution and automated crystallographic orientation mapping (ACOM) modes. The chemical bonding character is determined using electron energy loss spectroscopy (EELS). Despite the wide variation in composition, all the precipitates exhibit a hexagonal close-packed (h.c.p.) crystal structure and lattice parameters of aluminium nitride. The EDX measurement of ? 900 stoichiometrically different precipitates indicates intermediate structures between pure aluminium nitride and pure silicon manganese nitride, with a constant Si/Mn atomic ratio of ? 4. It is demonstrated that aluminium and silicon are interchangeably precipitated with the same local arrangement, while both Mn{sup 2+} and Mn{sup 3+} are incorporated in the h.c.p. silicon nitride interstitial sites. The oxidation of the silicon manganese nitrides most likely originates from the incorporation of oxygen during the decarburisation annealing process, thus creating extended planar defects such as stacking faults and inversion domain boundaries. The chemical composition of the inhibitors may be written as (AlN){sub x}(SiMn{sub 0.25}N{sub y}O{sub z}){sub 1?x} with x ranging from 0 to 1. - Highlights: • We study the structure of (Al,Si,Mn)N inhibitors in grain oriented electrical steels. • Inhibitors have the hexagonal close-packed symmetry with lattice parameters of AlN. • Inhibitors are intermediate structures between pure AlN and (Si,Mn)N with Si/Mn ? 4. • Al and Si share the same local arrangement; Mn is incorporated in both Mn{sup 2+} and Mn{sup 3+}. • Oxygen incorporation is invoked to account for the thermal stability of (Al,Si,Mn)N.

  6. Effect of chromium and manganese nitride alloying on the evolution of the fine structure in powder hot-forged steels

    NASA Astrophysics Data System (ADS)

    Mamonova, A. A.; Baglyuk, G. A.; Kurovskii, V. Ya.

    2015-06-01

    The effect of alloying with chromium and manganese nitrides is studied on a fine crystal structure of powder iron produced by hot forging. The features of the fine structure and the phase composition are found to strongly depend on the kind of alloying nitrides. It has been shown that the introduction of both nitrides in the initial composition of powder mixture causes an increase in the lattice parameter of a matrix, its defectiveness, and the dislocation density, which results in an increase in the hardness of steel alloyed with nitrides. The defectiveness of the matrix crystal lattice, the dislocation density, and the hardness of hot-forged steels are slightly higher when manganese nitride is used as a nitrogen-bearing additive.

  7. Local shear texture formation in adiabatic shear bands by high rate compression of high manganese TRIP steels

    NASA Astrophysics Data System (ADS)

    Li, J.; Yang, P.; Mao, W. M.; Cui, F. E.

    2015-04-01

    Local shear textures in ASBs of high manganese TRIP steels under high rate straining are determined and the influences of initial microstructure is analyzed using EBSD technique. It is seen that even at the presence of majority of two types of martensite before deformation, ASB is preferred to evolve in austenite, rather than in martenite, due to reverse transformation. Ultrafine grains of thress phases due to dynamic recrystallization are formed and all show shear textures. The less ?-martensite in ASB is distributed as islands and its preferred orientation can be found to originate from the variants in matrix. The grain orientation rotation around ASB in multi-phase alloy reveals significant influence of ?'- martensite on texture in ASB. The mechanism of local texture formation in ASB of high manganese TRIP steel is proposed in terms of the interaction of early TRIP and later reverse transformation.

  8. Effects of laser-shock processing on the microstructure and surface mechanical properties of hadfield manganese steel

    Microsoft Academic Search

    J. P. Chu; J. M. Rigsbee; G. Bana?; F. V. Lawrence; H. E. Elsayed-Ali

    1995-01-01

    The effects of laser-shock processing (LSP) on the microstructure, hardness, and residual stress of Hadfield manganese (1\\u000a pct C and 14 pct Mn) steels were studied. Laser-shock processing was performed using a Nd: glass phosphate laser with 600\\u000a ps pulse width and up to 120 J\\/pulse energy at power density above 1012 W\\/cm2. The effects of cold rolling and shot

  9. Application and assessment of ultrasonic inspection methods for flaw detection and characterization of manganese steel frogs

    NASA Astrophysics Data System (ADS)

    Cinson, A.; Diaz, A.; Prowant, M.

    2011-04-01

    Ultrasonic nondestructive examination (NDE) has a long and successful history of application across a wide array of industries, including nuclear, aerospace, and transportation sectors. In coarse-grained, cast Manganese (Mn) steel frog components, NDE/inspection challenges are encountered both in-field (after the frogs have been installed on a rail line) and at the manufacturing facilities during post-fabrication QA/QC activities. Periodically inherently flawed frogs are received from a manufacturer, and put into service, as most railroad operators do not have a means to conduct pre-service examinations on received components. Accordingly, there is a need for a pre-service inspection system that can provide a rapid, cost-effective and non-intrusive inspection capability for detection of defects, flaws, and other anomalies in frog components, in order to avoid premature initiation of cracks or failures of these components during service. This study focused on evaluating use of a volumetric phased-array ultrasonic testing (PA-UT) method to monitor fabrication quality assurance. In this preliminary assessment of using PA-UT, data were acquired at a frequency of 2.0 MHz on a known, flawed Mn steel frog component directly from a manufacturing facility. The component contained flaws commonly found as a result of the manufacturing process of these cast rail components. The data were analyzed and the anomalies were detected, localized and characterized. Results were compared against baseline radiographic data. A detection metric was reported in the form of signal-to-noise values.

  10. High temperature ductility loss in carbon-manganese and niobium-treated steels

    NASA Astrophysics Data System (ADS)

    Nachtrab, W. T.; Chou, Y. T.

    1986-11-01

    The causes of embrittlement in several plain carbon-manganese and niobium-treated steels between 800 and 1200 °C have been investigated. Tensile ductility was measured as a function of temperature and strain rate. Percent elongation and reduction in area were used to characterize the temperature dependence and severity of the ductility loss. The size, distribution, and composition of grain boundary precipitates were measured on extraction replicas. Grain boundary segregation was measured by AES on samples that were deformed at 900 °C before being fractured under ultra-high vacuum at room temperature. Segregation of impurity residual elements and grain boundary precipitation are the primary factors responsible for the observed ductility loss. The embrittlement results in a low ductility fracture which is largely intergranular through the austenite grain boundaries. Segregation of Cu, Sn, and Sb was found on the fracture surfaces of the embrittled samples. High temperature deformation was necessary to produce segregation as no segregation was detected in undeformed samples. Grain boundary precipitation, particularly AIN but also Nb (C,N), contributed to the embrittlement when there was a relatively fine distribution of precipitates along the austenite grain boundaries. The most severe ductility loss occurred when grain boundary precipitation combined with Cu, Sn, and Sb segregation.

  11. Substance flow analysis of phosphorus and manganese correlated with South Korean steel industry

    Microsoft Academic Search

    Yong-Soo Jeong; Kazuyo Matsubae-Yokoyama; Hironari Kubo; Jong-Jin Pak; Tetsuya Nagasaka

    2009-01-01

    Security of resources becomes more important than ever as the upward trend in the prices of mineral and natural resources continues. Phosphorus and manganese are important minerals to many countries. Phosphorus is in global demand, particularly for making fertilizers, and manganese is an indispensable element in industrial and consumer products. However, the raw materials for these two elements are restricted

  12. Welding fumes from stainless steel gas metal arc processes contain multiple manganese chemical species.

    PubMed

    Keane, Michael; Stone, Samuel; Chen, Bean

    2010-05-01

    Fumes from a group of gas metal arc welding (GMAW) processes used on stainless steel were generated using three different metal transfer modes and four different shield gases. The objective was to identify and measure manganese (Mn) species in the fumes, and identify processes that are minimal generators of Mn species. The robotic welding system was operated in short-circuit (SC) mode (Ar/CO2 and He/Ar), axial spray (AXS) mode (Ar/O2 and Ar/CO2), and pulsed axial-spray (PAXS) mode (Ar/O2). The fumes were analyzed for Mn by a sequential extraction process followed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis, and by X-ray diffraction (XRD). Total elemental Mn, iron (Fe), chromium (Cr) and nickel (Ni) were separately measured after aqua regia digestion and ICP-AES analysis. Soluble Mn2+, Fe2+, Fe3+, and Ni2+ in a simple biological buffer (phosphate-buffered saline) were determined at pH 7.2 and 5.0 after 2 h incubation at 37 C by ion chromatography. Results indicate that Mn was present in soluble form, acid-soluble form, and acid-soluble form after reduction by hydroxylamine, which represents soluble Mn0 and Mn2+ compounds, other Mn2+ compounds, and (Mn3+ and Mn4+) compounds, respectively. The dominant fraction was the acid-soluble Mn2+ fraction, but results varied with the process and shield gas. Soluble Mn mass percent in the fume ranged from 0.2 to 0.9%, acid-soluble Mn2+ compounds ranged from 2.6 to 9.3%, and acid plus reducing agent-soluble (Mn3+ and Mn4+) compounds ranged from 0.6 to 5.1%. Total Mn composition ranged from 7 to 15%. XRD results showed fumes had a crystalline content of 90-99% Fe3O4, and showed evidence of multiple Mn oxides, but overlaps and weak signals limited identification. Small amounts of the Mn2+ in the fume (<0.01 to ? 1% or <0.1 to ? 10 microg ml(-1)) and Ni2+ (<0.01 to ? 0.2% or <0.1 to ? 2 mg ml(-1)) ions were found in biological buffer media, but amounts were highly dependent on pH and the welding process. Mn generation rates for the fractions were tabulated, and the influence of ozone is discussed. The conclusions are that exposures to welding fumes include multiple Mn species, both soluble and insoluble, and that exposures to Mn species vary with specific processes and shield gases. PMID:21491680

  13. Investigations on Laser Beam Welding Dissimilar Material Combinations of Austenitic High Manganese (FeMn) and Ferrite Steels

    NASA Astrophysics Data System (ADS)

    Behm, Velten; Höfemann, Matthias; Hatscher, Ansgar; Springer, André; Kaierle, Stefan; Hein, David; Otto, Manuel; Overmeyer, Ludger

    For the past few years the customer's demand for more fuel efficient and at the same time safer vehicles has steadily increased. Consequently, light weight design has become one of the main interests in engineering. With regard to sheet metal components, a new class of high manganese steels, based on the TWIP (twinning induced plasticity) effect, provides the opportunity of shaping light weight designedthin and complex sheet metal geometries with advanced crash performance. In terms of weldability, due to their thermo-physical properties (high content of C, Mn, Al, Si), FeMn steels have to be handled differently in comparison to conventional steel grades. Particularly dissimilar material combinations of FeMn and ferrite steels are in the center of interest for industrial applications. This study reveals that metallurgical properties of dissimilar welding seams can be influenced considerably by laser beam welding, resulting in a change of the mechanical properties of the seam which is practicable without using filler material as described in (Flügge et al., 2011).

  14. Nitrogen distribution in austenitic high-nitrogen chromium-manganese steel under friction and high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Shabashov, V. A.; Korshunov, L. G.; Sagaradze, V. V.; Kataeva, N. V.; Zamatovskii, A. E.; Litvinov, A. V.; Lyashkov, K. A.

    2013-08-01

    Mössbauer spectroscopy and electron microscopic analysis were used to investigate the precipitation of products of cellular decomposition and their dissolution in high-nitrogen chromium-manganese steel FeMn22Cr18N0.8 under room-temperature severe deformation via dry sliding friction and high pressure torsion in Bridgman anvils. It has been established that the nitrogen content increases in interstitial positions in the quenched and pre-aged alloy due to the strain-induced dissolution of chromium nitrides, which are contained in the products of decomposition. Mössbauer analysis showed that the friction-induced dissolution of chromium nitrides occurs at a depth of more than 10 ?m. Aging reduces the amount of nitrogen that occurred in the solid solution upon deformation. This is explained by the additional energy consumed in grinding the decomposition products.

  15. Manganese and nitrogen in stainless steel SMA welds for cryogenic service

    Microsoft Academic Search

    C. N. Mc Cowan; T. A. Siewart; R. P. Reed; F. B. Lake

    1987-01-01

    Evaluation of a shielded metal arc (SMA) weld test matrix in which manganese (1.5 to 10 wt-%) and nitrogen (0.04 to 0.26wt-%) were varied independently has clarified the effect of these elements on cryogenic mechanical properties and predicted ferrite number (FN). Several molybdenum and boron additions were also made, but they had no observable effect on strength or Charpy V-notch

  16. Effect of manganese and nitrogen on the solidification mode in austenitic stainless steel welds

    Microsoft Academic Search

    N. Suutala

    1982-01-01

    The macrostructures and microstructures of thirty different austenitic stainless welds alloyed with manganese and Jor nitrogen\\u000a are analyzed. Comparison of the results with those obtained from normal welds of the AISIJAWS 300 series indicates that the\\u000a solidification mode and Ferrite Number can be predicted adequately using chromium and nickel equivalents. The solidification\\u000a mode in the normal and nitrogen-alloyed welds can

  17. Carburization of a high-manganese, low-carbon steel by Methane-Nitrogen gas mixtures

    Microsoft Academic Search

    F. Nestor; W. Rostoker; R. F. Domagala

    1979-01-01

    It has been shown that an experimental 4 wt pet Mn steel can be successfully treated to produce a very high surface hardness\\u000a (in excess of 700 VPN) and a substantial core strength. The base steel has sufficient hardenability to give through-hardening\\u000a without quenching from the carburization furnace.

  18. Effect of Grain Refinement on the Mechanical Properties of a Nickel- and Manganese-Free High Nitrogen Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Akbari, Alireza; Mohammadzadeh, Roghayeh

    2015-04-01

    Grain coarsening due to the high temperature exposure deteriorates mechanical properties of the high nitrogen austenitic stainless steels (HNASSs) produced by solution nitriding. To improve mechanical properties, the grains of nickel and manganese-free Fe-23Cr-2.4Mo-1.2N HNASS plates fabricated by pressurized solution nitriding were refined using a two-stage heat treatment process. Structural and mechanical properties were investigated using X-ray diffraction, optical microscopy, scanning and transmission electron microscopy, hardness and tensile testing and compared with that of the conventional AISI 316L steel. The results show that the as-produced HNASS exhibits uniform deformation up to failure without necking and brittle inter-granular fracture. By grain refinement, the yield and tensile strengths as well as the elongation to failure are increased by 17.8, 21.2, and 108.3 pct, respectively, as compared to the as-produced HNASS. However, despite more than a double increase in tensile toughness and elongation to failure, the brittle inter-granular fracture is not suppressed. The HNASSs plastically deform through formation of straight slip bands. TEM observations indicate development of planar arrays of dislocations in tensile-deformed HNASSs. The enhancement in tensile strength and toughness by grain refinement is discussed on the basis of straight slip bands formation, number of dislocations in pile-ups, and incompatibility strain developed between adjacent grains.

  19. Effects of laser-shock processing on the microstructure and surface mechanical properties of Hadfield manganese steel

    SciTech Connect

    Chu, J.P. [National Taiwan Ocean Univ., Keelung (Taiwan, Province of China). Inst. of Materials Engineering; Rigsbee, J.M. [Univ. of Alabama, Birmingham, AL (United States). Dept. of Materials Science and Engineering; Banas, G.; Lawrence, F.V. [Univ. of Illinois, Urbana, IL (United States). Dept. of Civil Engineering; Elsayed-Ali, H.E. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Electrical and Computer Engineering

    1995-06-01

    The effects of laser-shock processing (LSP) on the microstructure, hardness, and residual stress of Hadfield manganese (1 pct C and 14 pct Mn) steels were studied. Laser-shock processing was performed using a Nd:glass phosphate laser with 600 ps pulse width and up to 120 J/pulse energy at power density above 10{sup 12}W/cm{sup 2}. The effects of cold rolling and shot peening were also studied for comparison. Laser-shock processing caused extensive formation of {var_epsilon} hexagonal close-packed (hcp) martensite (35 vol pct), producing up to a 130 pct increase of surface hardness. The surface hardness increase was 40 to 60 pct for the shot-peened specimen and about 60 pct for the cold-rolled specimen. The LSP strengthening effect on Hadfield steel was attributed to the combined effects of the partial dislocation/stacking fault arrays and the grain refinement due to the presence of the {var_epsilon}-hcp martensite. For the cold-rolled and shot-peened specimens, the strengthening was a result of {var_epsilon}-hcp martensite and twins with dislocation effects, respectively. Shot peening resulted in a relatively higher compressive residual stress throughout the specimen than LSP.

  20. Characterization of Nonmetallic Inclusions in High-Manganese and Aluminum-Alloyed Austenitic Steels

    NASA Astrophysics Data System (ADS)

    Park, Joo Hyun; Kim, Dong-Jin; Min, Dong Joon

    2012-07-01

    The effects of Al and Mn contents on the size, composition, and three-dimensional morphologies of inclusions formed in Fe- xMn- yAl ( x = 10 and 20 mass pct, y = 1, 3, and 6 mass pct) steels were investigated to enhance our understanding of the inclusion formation behavior in high Mn-Al-alloyed steels. By assuming that the alumina is a dominant oxide compound, the volume fraction of inclusions estimated from the chemical analysis, i.e., insoluble Al, in the Fe-Mn-3Al steels was larger than the inclusion volume fractions in the Fe-Mn-1Al and Fe-Mn-6Al steels. A similar tendency was found in the analysis of inclusions from a potentiostatic electrolytic extraction method. This finding could be explained from the terminal velocities of the compounds, which was affected by the thermophysical properties of Fe-Mn-Al steels. The inclusions formed in the Fe-Mn-Al-alloyed steels are classified into seven types according to chemistry and morphology: (1) single Al2O3 particle, (2) single AlN or AlON particle, (3) MnAl2O4 single galaxite spinel particle, (4) Al2O3(-Al(O)N) agglomerate, (5) single Mn(S,Se) particle, (6) oxide core with Mn(S,Se) skin (wrap), and (7) Mn(S,Se) core with Al2O3(-Al(O)N) aggregate (or bump). The Mn(S,Se) compounds were formed by the contamination of the steels by Se from the electrolytic Mn. Therefore, the raw materials (Mn) should be used carefully in the melting and casting processes of Fe-Mn-Al-alloyed steels.

  1. State-of-the-Science of High Manganese TWIP Steels for Automotive Applications

    NASA Astrophysics Data System (ADS)

    de Cooman, B. C.; Chen, L.; Kim, Han Soo; Estrin, Y.; Kim, S. K.; Voswinckel, H.

    Recent trends in automotive industry towards improved passenger safety and reduced weight have led to a great interest in AHSS (Advanced High Strength Steel), and DP, TRIP, CP, MA and high-Mn TWIP (TWinning Induced Plasticity) steels are particularly promising due to their superior toughness and ductility. The properties of low SFE (Stacking Fault Energy) austenitic high Mn FeMnC steel exhibiting twinning-induced plasticity have recently been analyzed in detail. It is argued that although the mechanical properties of TRIP and TWIP steels are often assumed to be solely due to effects related to straininduced transformation and deformation twinning, respectively, other mechanisms may also play an essential role such as point-defect cluster formation, planar glide, pseudo-twinning, short range ordering, and dynamic strain ageing, e.g. in the case of TWIP steel. At low strain rates, the plastic deformation of TWIP steels is often controlled by the movement of very few well-defined localized deformation bands. The formation and propagation of these Portevin-LeChatelier (PLC) bands lead to serrated stress-strain curves, exhibiting a small negative strain rate sensitivity.

  2. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...carbon steel, plain nickel-alloy steel, carbon-manganese-alloy steel, manganese-vanadium-alloy steel, and carbon-silicon steel may convert to graphite. (b) (Reproduces 124.2.B.) Upon prolonged exposure to temperatures above...

  3. The influence of aluminum and carbon on the abrasion resistance of high manganese steels

    NASA Astrophysics Data System (ADS)

    Buckholz, Samuel August

    Abrasive wear testing of lightweight, austenitic Fe-Mn-Al-C cast steel has been performed in accordance with ASTM G65 using a dry sand, rubber wheel, abrasion testing apparatus. Testing was conducted on a series of Fe-30Mn-XAl-YC-1Si-0.5Mo chemistries containing aluminum levels from 2.9 to 9.5 wt.% and carbon levels from 0.9 to 1.83 wt.%. Solution treated materials having an austenitic microstructure produced the highest wear resistance. Wear resistance decreased with higher aluminum, lower carbon, and higher hardness after age hardening. In the solution treated condition the wear rate was a strong function of the aluminum to carbon ratio and the wear rate increased with a parabolic dependence on the Al/C ratio, which ranged from 1.8 to 10.2. Examination of the surface wear scar revealed a mechanism of plowing during abrasion testing and this method of material removal is sensitive to work hardening rate. Work hardening behavior was determined from tensile tests and also decreased with increasing Al/C ratio and after aging hardening. The loss of wear resistance is related to short range ordering of Al and C in the solution treated materials and kappa-carbide precipitation in age hardened materials and both contribute to planar slip and lower work hardening rates. A high carbon tool steel (W1) and a bainitic low alloy steel (SAE 8620) were also tested for comparison. A lightweight steel containing 6.5 wt.% Al and 1.2 wt.% C has wear resistance comparable to within 5% of the bainitic SAE 8620 steel forging currently used for the Bradley Fighting Vehicle track shoe and this cast Fe-Mn-Al-C steel, at equivalent tensile properties, would be 10% lighter.

  4. Elevated Airborne Exposures of Teenagers to Manganese, Chromium, and Iron from Steel Dust and New York City’s Subway System

    PubMed Central

    CHILLRUD, STEVEN N.; EPSTEIN, DAVID; ROSS, JAMES M.; SAX, SONJA N.; PEDERSON, DEE; SPENGLER, JOHN D.; KINNEY, PATRICK L.

    2011-01-01

    There is increasing interest in potential health effects of airborne exposures to hazardous air pollutants at relatively low levels. This study focuses on sources, levels, and exposure pathways of manganese, chromium, and iron among inner-city high school students in New York City (NYC) and the contribution of subways. Samples of fine particulate matter (PM2.5) were collected during winter and summer over 48 h periods in a variety of settings including inside homes, outdoors, and personal samples (i.e., sampling packs carried by subjects). PM2.5 samples were also collected in the NYC subway system. For NYC, personal samples had significantly higher concentrations of iron, manganese, and chromium than did home indoor and ambient samples. The ratios and strong correlations between pairs of elements suggested steel dust as the source of these metals for a large subset of the personal samples. Time–activity data suggested NYC subways as a likely source of these elevated personal metals. In duplicate PM2.5 samples that integrated 8 h of underground subway exposure, iron, manganese, and chromium levels (>2 orders of magnitude above ambient levels) and their ratios were consistent with the elevated personal exposures. Steel dust in the NYC subway system was the dominant source of airborne exposures to iron, manganese, and chromium for many young people enrolled in this study, with the same results expected for other NYC subway riders who do not have occupational exposures to these metals. However, there are currently no known health effects at the exposure levels observed in this study. PMID:14968857

  5. Globally sustainable manganese metal production and use

    Microsoft Academic Search

    Karen Hagelstein

    2009-01-01

    The “cradle to grave” concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices—such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production

  6. Manganese recycling in the United States in 1998

    USGS Publications Warehouse

    Jones, Thomas S.

    2001-01-01

    This report describes the flow and processing of manganese within the U.S. economy in 1998 with emphasis on the extent to which manganese is recycled. Manganese was used mostly as an alloying agent in alloys in which it was a minor component. Manganese was recycled mostly within scrap of iron and steel. A small amount was recycled within aluminum used beverage cans. Very little manganese was recycled from materials being recovered specifically for their manganese content. For the United States in 1998, 218,000 metric tons of manganese was estimated to have been recycled from old scrap, of which 96% was from iron and steel scrap. Efficiency of recycling was estimated as 53% and recycling rate as 37%. Metallurgical loss of manganese was estimated to be about 1.7 times that recycled. This loss was mostly into slags from iron and steel production, from which recovery of manganese has yet to be shown economically feasible.

  7. Manganese neurotoxicity.

    PubMed

    Dobson, Allison W; Erikson, Keith M; Aschner, Michael

    2004-03-01

    Manganese is an essential trace element and it is required for many ubiquitous enzymatic reactions. While manganese deficiency rarely occurs in humans, manganese toxicity is known to occur in certain occupational settings through inhalation of manganese-containing dust. The brain is particularly susceptible to this excess manganese, and accumulation there can cause a neurodegenerative disorder known as manganism. Characteristics of this disease are described as Parkinson-like symptoms. The similarities between the two disorders can be partially explained by the fact that the basal ganglia accumulate most of the excess manganese compared with other brain regions in manganism, and dysfunction in the basal ganglia is also the etiology of Parkinson's disease. It has been proposed that populations already at heightened risk for neurodegeneration may also be more susceptible to manganese neurotoxicity, which highlights the importance of investigating the human health effects of using the controversial compound, methylcyclopentadienyl manganese tricarbonyl (MMT), in gasoline to increase octane. The mechanisms by which increased manganese levels can cause neuronal dysfunction and death are yet to be elucidated. However, oxidative stress generated through mitochondrial perturbation may be a key event in the demise of the affected central nervous system cells. Our studies with primary astrocyte cultures have revealed that they are a critical component in the battery of defenses against manganese-induced neurotoxicity. Additionally, evidence for the role of oxidative stress in the progression of manganism is reviewed here. PMID:15105259

  8. (Data in thousand metric tons, gross weight, unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    United States. The majority of ore consumption was related to steel production, directly in pig iron: Domestic manganese demand was bolstered by increased raw steel production through at least the first one Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 1998

  9. (Data in thousand metric tons gross weight unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese has not been produced

    E-print Network

    Torgersen, Christian

    . Most ore consumption was related to steel production, directly in pig iron manufacture and indirectly to affect the manganese market in 2009. U.S. steel production in 2009 was 40% less than that in 2008 Production and Use: Manganese ore containing 35% or more manganese has not been produced domestically since

  10. (Data in thousand metric tons gross weight unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese has not been produced

    E-print Network

    Torgersen, Christian

    . Most ore consumption was related to steel production, directly in pig iron manufacture and indirectly), coincided with the growth in the manganese market during 2010. U.S. steel production in 2010 was projected Production and Use: Manganese ore containing 35% or more manganese has not been produced domestically since

  11. (Data in thousand metric tons gross weight unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese has not been produced

    E-print Network

    Torgersen, Christian

    . Most ore consumption was related to steel production, directly in pig iron manufacture and indirectly, and Issues: U.S. steel production in 2012 was projected to be 4% more than that in 2011. Imports of manganese Production and Use: Manganese ore containing 35% or more manganese has not been produced domestically since

  12. MANGANESE TOURMALINES

    Microsoft Academic Search

    M. N. Slivko

    1961-01-01

    The role of manganese in the chemical composition and coloring of tourmaline is discussed. It is shown that manganese tourmaline-tsilaisite is similar to tourmaline-elbaite in composition and condition formation. The miscibility in the sherlite-elbaite-tsilaisite system is complete, but in the sherlite-dravite-tsilaisite system there is a gap between the dravite and tsilaisite, similar to the relationship between dravite and elbaite.Manganese may

  13. Nitrogen in chromium-manganese stainless steels: a review on the evaluation of stacking fault energy by computational thermodynamics

    NASA Astrophysics Data System (ADS)

    Mosecker, Linda; Saeed-Akbari, Alireza

    2013-06-01

    Nitrogen in austenitic stainless steels and its effect on the stacking fault energy (SFE) has been the subject of intense discussions in the literature. Until today, no generally accepted method for the SFE calculation exists that can be applied to a wide range of chemical compositions in these systems. Besides different types of models that are used from first-principle to thermodynamics-based approaches, one main reason is the general lack of experimentally measured SFE values for these steels. Moreover, in the respective studies, not only different alloying systems but also different domains of nitrogen contents were analyzed resulting in contrary conclusions on the effect of nitrogen on the SFE. This work gives a review on the current state of SFE calculation by computational thermodynamics for the Fe-Cr-Mn-N system. An assessment of the thermodynamic effective Gibbs free energy, \\Delta G^{\\gamma \\to \\varepsilon } , model for the \\gamma \\to \\varepsilon phase transformation considering existing data from different literature and commercial databases is given. Furthermore, we introduce the application of a non-constant composition-dependent interfacial energy, ??/?, required to consider the effect of nitrogen on SFE in these systems.

  14. Mild steel welding fume causes manganese accumulation and subtle neuroinflammatory changes but not overt neuronal damage in discrete brain regions of rats after short-term inhalation exposure.

    PubMed

    Antonini, James M; Sriram, Krishnan; Benkovic, Stanley A; Roberts, Jenny R; Stone, Samuel; Chen, Bean T; Schwegler-Berry, Diane; Jefferson, Amy M; Billig, Brenda K; Felton, Christopher M; Hammer, Mary Ann; Ma, Fang; Frazer, David G; O'Callaghan, James P; Miller, Diane B

    2009-11-01

    Serious questions have been raised by occupational health investigators regarding a possible causal association between neurological effects in welders and the presence of manganese (Mn) in welding fume. Male Sprague-Dawley rats were exposed by inhalation to 40 mg/m(3) of gas metal arc-mild steel (MS) welding fume for 3 h/day for 10 days. Generated fume was collected in the animal chamber during exposure, and particle size, composition, and morphology were characterized. At 1 day after the last exposure, metal deposition in different organ systems and neurological responses in dopaminergic brain regions were assessed in exposed animals. The welding particles were composed primarily of a complex of iron (Fe) and Mn and were arranged as chain-like aggregates with a significant number of particles in the nanometer size range. Mn was observed to translocate from the lungs to the kidney and specific brain regions (olfactory bulb, cortex, and cerebellum) after MS fume inhalation. In terms of neurological responses, short-term MS fume inhalation induced significant elevations in divalent metal ion transporter 1 (Dmt1) expression in striatum and midbrain and significant increases in expression of proinflammatory chemokines (Ccl2, Cxcl2) and cytokines (IL1beta, TNFalpha) in striatum. In addition, mRNA and protein expression of glial fibrillary acidic protein (GFAP) was significantly increased in striatum after MS fume exposure. However, the 10-day MS welding fume inhalation did not cause any changes in dopamine and its metabolites or GABA in dopaminergic brain regions nor did it produce overt neural cell damage as assessed by histopathology. In summary, short-term MS welding fume exposure led to translocation of Mn to specific brain regions and induced subtle changes in cell markers of neuroinflammatory and astrogliosis. The neurofunctional significance of these findings currently is being investigated in longer, more chronic welding fume exposure studies. PMID:19782702

  15. Dynamics of phase transformations and microstructure evolution in carbon-manganese steel arc welds using time-resolved synchrotron X-ray diffraction.

    PubMed

    Wong, Joe; Ressler, Thorsten; Elmer, John W

    2003-03-01

    Phase transformations that occur in both the heat-affected zone (HAZ) and the fusion zone (FZ) of a carbon-manganese steel spot weld have been investigated using time-resolved X-ray diffraction (TRXRD) with time resolutions down to 50 ms. It is found that in both zones the gamma(f.c.c.) --> alpha(b.c.c.) transformation on cooling is twice as fast as the forward transformation of alpha --> gamma on heating. Profile analysis of the major Bragg reflections recorded in the TRXRD patterns reveals similarities and differences in the microstructural evolution with time in the HAZ and in the FZ. The latter undergoes melting and solidification in addition to solid-state transformations. With increasing temperature, the (110) d-spacing of the alpha phase prior to and during the alpha --> gamma transformation and the (111) d-spacing of the gamma phase just after the same transformation exhibit a decrease. The observed (and unusual) lattice contraction with temperature rise may be attributed to chemical effects, such as carbide precipitation in the alpha matrix, and/or mechanical effects due to stress relief. In the FZ, the gamma-Fe that forms has a preferential (200) texture on solidification of the liquid, whereas, on cooling in the HAZ, the gamma-Fe retains largely a (111) texture that is induced in the alpha --> gamma transformation on heating. On cooling in the HAZ, the width of the gamma(111) reflection increases initially, which is indicative of microstrain developing in the f.c.c. lattice, but decreases as expected, with a reduction of thermal disorder, on further cooling until the completion of the gamma --> alpha transformation. In the FZ, however, the microstrain in the gamma phase increases steadily on solidification and more rapidly for the duration of the gamma --> alpha transformation on further cooling. The final microstructure of the FZ is likely to consist of a single alpha phase dispersed in two morphological entities, whereas in the HAZ the alpha phase persists in one morphological entity in the final microstructure. PMID:12606794

  16. Synthesis and determination of manganese carbonate and manganese-54 carbonate

    SciTech Connect

    King, B.D.; Lassiter, J.W.; Neathery, M.W.; Miller, W.J.

    1980-04-01

    A method was developed by which radioactive manganese, manganese-54 carbonate could be produced. This was accomplished by reacting manganese-54 chloride, manganese chloride tetrahydrate, and sodium bicarbonate. This reaction produced manganese-54 carbonate mixed with stable manganese. The purity of the manganese carbonate (manganese-54 carbonate) was determined by the use of x-ray diffraction methods. All material was the carbonate form of manganese (manganese-54 carbonate).

  17. (Data in thousand metric tons, gross weight, unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    United States. The majority of ore consumption was related to steel production, directly in pig iron.2 Electrolytic metal 9 0.5 9 2 1r Events, Trends, and Issues: Although raw steel production, a major determinant Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 1997

  18. (Data in thousand metric tons gross weight unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese has not been produced

    E-print Network

    Torgersen, Christian

    . Most ore consumption was related to steel production, directly in pig iron manufacture and indirectly 91 -- Ferromanganese, high-carbon 356 356 91 34 Events, Trends, and Issues: U.S. steel production Production and Use: Manganese ore containing 35% or more manganese has not been produced domestically since

  19. (Data in thousand metric tons gross weight unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    consumption was related to steel production, directly in pig iron manufacture and indirectly through upgrading in producer and consumer stock releases. Through September 2008, domestic steel production was 4% higher than Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 2008

  20. (Data in thousand metric tons, gross weight, unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    United States. The majority of ore consumption was related to steel production, directly in pig iron metal 10 0.02 10 2 Events, Trends, and Issues: A slight further advance in raw steel production Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 1996

  1. (Data in thousand metric tons, gross weight, unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    and the Midwestern United States. Most ore consumption was related to steel production, directly in pig iron 2 Events, Trends, and Issues: Through September, steel production, the principal determinant Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 2002

  2. Synthesis and determination of manganese carbonate and manganese-54 carbonate

    Microsoft Academic Search

    B. D. King; J. W. Lassiter; M. W. Neathery; W. J. Miller

    1980-01-01

    A method was developed by which radioactive manganese, manganese-54 carbonate could be produced. This was accomplished by reacting manganese-54 chloride, manganese chloride tetrahydrate, and sodium bicarbonate. This reaction produced manganese-54 carbonate mixed with stable manganese. The purity of the manganese carbonate (manganese-54 carbonate) was determined by the use of x-ray diffraction methods. All material was the carbonate form of manganese

  3. Hydrogen embrittlement of structural steels

    Microsoft Academic Search

    Somerday; Brian P

    2010-01-01

    Carbon-manganese steels are candidates for the structural materials in hydrogen gas pipelines, however it is well known that these steels are susceptible to hydrogen embrittlement. Decades of research and industrial experience have established that hydrogen embrittlement compromises the structural integrity of steel components. This experience has also helped identify the failure modes that can operate in hydrogen containment structures. As

  4. Effect of the carbide phase on the tribological properties of high-manganese antiferromagnetic austenitic steels alloyed with vanadium and molybdenum

    Microsoft Academic Search

    L. G. Korshunov; I. I. Kositsina; V. V. Sagaradze; N. L. Chernenko

    2011-01-01

    Effect of special carbides (VC, M\\u000a 6C, Mo2C) on the wear resistance and friction coefficient of austenitic stable (M\\u000a s below ?196°C) antiferromagnetic (T\\u000a N = 40–60°C) steels 80G20F2, 80G20M2, and 80G20F2M2 has been studied. The structure and the effective strength (microhardness\\u000a H\\u000a surf, shear resistance ?) of the surface layer of these steels have been studied using optical and

  5. Chronic manganese intoxication

    SciTech Connect

    Huang, C.C.; Chu, N.S.; Lu, C.S.; Wang, J.D.; Tsai, J.L.; Tzeng, J.L.; Wolters, E.C.; Calne, D.B. (Chang Gung Medical College Hospital, Taipei, Taiwan (China))

    1989-10-01

    We report six cases of chronic manganese intoxication in workers at a ferromanganese factory in Taiwan. Diagnosis was confirmed by assessing increased manganese concentrations in the blood, scalp, and pubic hair. In addition, increased manganese levels in the environmental air were established. The patients showed a bradykinetic-rigid syndrome indistinguishable from Parkinson's disease that responded to treatment with levodopa.

  6. Manganese in Narragansett Bay

    Microsoft Academic Search

    WILLIAM F. GRAHAM; MICHAEL L. BENDER; GARY P. KLINKHAMMER

    1976-01-01

    Concentrations of dissolved manganese and particulate mangancsc and aluminum were determined in samples from Narragansett Bay, Rhode Island, and its surrounding rivers. Total manganese is approximately conservative, but dissolved and particulate manganese are not. Desorption may occur in the tidal rivers at low salinities. Most riverine manga- nest is dissolved but mangancsc in the bay is predominantly particulate, probably due

  7. (Data in thousand metric tons, gross weight, unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced

    E-print Network

    Torgersen, Christian

    and the Midwestern United States. Most ore consumption was related to steel production, directly in pig iron for manganese ferroalloy demand usually falls in the range of 1% to 2% and is tied to steel production. Through the first 8 months of 2003, however, domestic steel production was the same as that for the same period

  8. (Data in thousand metric tons, gross weight, unless otherwise specified) Domestic Production and Use: Manganese ore containing 35% or more manganese was not produced domestically

    E-print Network

    Torgersen, Christian

    and the Midwestern United States. The majority of ore consumption was related to steel production, directly in pig Production and Use: Manganese ore containing 35% or more manganese was not produced domestically in 2001 of ore were used for such nonmetallurgical purposes as production of dry cell batteries, as an ingredient

  9. Synthesis and determination of manganese carbonate and manganese-54 carbonate.

    PubMed

    King, B D; Lassiter, J W; Neathery, M W; Miller, W J

    1980-04-01

    A method was developed by which radioactive manganese, manganese-54 carbonate (with a high specific activity), could be produced. This was accomplished by reacting manganese-54 chloride, manganese chloride tetrahydrate, and sodium bicarbonate. This reaction produced manganese-54 carbonate (specific activity .35 mCi/mg manganese mixed with stable manganese. The purity of the manganese carbonate (manganese-54 carbonate) was determined by the use of x-ray diffraction methods. One method compared "d" spacings (distance in angstroms between lattice planes of a crystal) with standard and index values for pure manganese carbonate. Another method compared x-ray diffractograms of the synthesized product with standard manganese carbonate. By both methods all material was the carbonate form of manganese (manganese-54 carbonate). PMID:7381087

  10. Volatilization from PCA steel alloy

    SciTech Connect

    Hagrman, D.L.; Smolik, G.R.; McCarthy, K.A.; Petti, D.A. [Lockheed Martin Idaho Technologies Company, Idaho Falls, ID (United States)

    1996-12-31

    The mobilizations of key components from Primary Candidate Alloy (PCA) steel alloy have been measured with laboratory-scale experiments. The experiments indicate most of the mobilization from PCA steel is due to oxide formation and spalling but that the spalled particles are large enough to settle rapidly. Based on the experiments, models for the volatilization of iron, manganese, and cobalt from PCA steel in steam and molybdenum from PCA steel in air have been derived. 6 refs., 3 figs.

  11. Design of steel energy absorbing restrainers and their incorporation into nuclear power plants for enhanced safety. Volume 3. Evaluation of commercial steels

    Microsoft Academic Search

    W. S. Owen; R. M. N. Pelloux; R. O. Ritchie; M. Faral; T. Ohhashi; J. Toplosky; S. J. Hartman; V. F. Zackay; E. R. Parker

    1979-01-01

    The low cycle fatigue characteristics of types 301 and 303 stainless steels, Hadfield manganese steel, and 300-M were determined. In relation to the performance of a solid state damping device, Hadfield manganese steel appeared to be most desirable due to high energy absorption, good fatigue lifetime, and low temperature sensitivity. The changes in mechanical properties accompanying the metastable austenite transformation

  12. Manganese 2 -Complexes as Auxiliaries

    E-print Network

    Lepore, Salvatore D.

    reaction with methylcyclopentadienyl manganese tricarbonyl. This complex readily underwent aldol reactions by Franck-Neumann demonstrating that alkynyl esters 2 -complexed to methylcyclopentadienyl manganeseManganese 2 -Complexes as Auxiliaries for Stereoselective Aldol Synthesis of Allenyl Carbinols

  13. Effect of non-magnetic inclusions in magnetic specimens on defect detection sensitivity using active infrared thermography

    NASA Astrophysics Data System (ADS)

    Lahiri, B. B.; Bagavathiappan, S.; Sebastian, Libins T.; Philip, John; Jayakumar, T.

    2015-01-01

    We study the effect of non-magnetic inclusions in the defect regions on defect detection sensitivity using alternating magnetic field assisted infrared thermography. The effect of inclusions on the resulting surface temperature profiles around the defect regions are monitored using infrared thermography under the magnetic excitation. Four mild steel specimens with simulated rectangular slots of depths 8.0, 3.3, 3.0 and 5.0 mm, filled with three different non-magnetic inclusions, viz. clay, grease and wax are studied. Under an alternating magnetic field excitation, the induced eddy current in the mild steel specimens produces Joule's heating on the surfaces, which is monitored in a non-contact way. As the non-magnetic inclusions act as a thermal insulator to the alternating magnetization induced heating, a clear thermal contrast at the defect boundaries is seen. The defect regions are clearly discernible from the thermal images and defect widths are estimated from the horizontal temperature profiles. It is observed that the temperature difference between the defect and defect-free regions initially decreases with time up to a certain time (called inversion time) and beyond that the temperature difference increases with time for clay and grease filled defects. The peak temperature difference between the defect and defect-free regions decreases with defect depth due to the magnetic flux leakage from the defect regions. The normalized temperature decay rate, determined from the blind sides of the specimens, is found to decrease with the defect depth. The sensitivity of the depth estimation procedure is higher for inclusions with lower thermal diffusivity values. This study shows the efficacy of low frequency alternating magnetic field induced heating procedure for the detection of defects filled with non-magnetic inclusions in magnetic specimens using active infrared thermography.

  14. Small angle neutron scattering modeling of copper-rich precipitates in steel

    SciTech Connect

    Spooner, S.

    1997-11-01

    The magnetic to nuclear scattering intensity ratio observed in the scattering from copper rich precipitates in irradiated pressure vessel steels is much smaller than the value of 11.4 expected for a pure copper precipitate in iron. A model for precipitates in pressure vessel steels which matches the observed scattering typically incorporates manganese, nickel, silicon and other elements and it is assumed that the precipitate is non-magnetic. In the present work consideration is given to the effect of composition gradients and ferromagnetic penetration into the precipitate on the small angle scattering cross section for copper rich clusters as distinguished from conventional precipitates. The calculation is an extension of a scattering model for micelles which consist of shells of varying scattering density. A discrepancy between recent SANS scattering experiments on pressure vessel steels was found to be related to applied magnetic field strength. The assumption of cluster structure and its relation to atom probe FIM findings as well as the effects of insufficient field for magnetic saturation is discussed.

  15. Ferromagnetism in Manganese Compounds

    Microsoft Academic Search

    R. O. Zaitsev

    1998-01-01

    The ferromagnetic instability in a system of manganese cations and oxygen, nitrogen and phosphorus anions on the basis of the strong electron-electron interaction is studied. The phase diagram for the existence of ferromagnetic ordering depending on the filling p6-shells of anions and dl0-shells of manganese is constructed.

  16. BIOLOGICAL EFFECTS OF MANGANESE

    EPA Science Inventory

    The biological effects of manganese were studied in a town on the coast of Dalmatia in which a ferromanganese plant has been operating since before World War II. The study focused on the question of whether the exposure to manganese can cause a higher incidence of respiratory dis...

  17. Manganese, the stress reliever.

    PubMed

    Latour, J-M

    2015-01-01

    Convergent evidence has emerged over the past decade to highlight the role of manganese as a key player in the defenses that many organisms are building to fight oxidative stress. For redox processes replacing iron by manganese requires adaptation at different levels. The aim of this perspective is to summarize recent important observations and to analyze the implications of the present knowledge for resolving future issues. PMID:25434324

  18. Quantum Confinement and Non-Magnetic-Doped Dilute Magnetic Semiconductors

    Microsoft Academic Search

    Hyunwook Kwak; Tzu-Liang Chan; James R. Chelikowsky

    2008-01-01

    Dilute magnetic semiconductors are of interest for their unique magnetic properties and their promising role in development of ``spintronic'' semiconductor devices. Recently, a new dimension has been brought to this class of material by observing room temperature ferromagnetism in non-magnetic doped semiconductors and insulators. Using real-space pseudopotential applied to nitrogen-doped ZnO nanowires and nanocrystals, we report the theoretical evidence of

  19. Robustness against non-magnetic impurities in topological superconductors

    NASA Astrophysics Data System (ADS)

    Nagai, Y.; Ota, Y.; Machida, M.

    2014-12-01

    We study the robustness against non-magnetic impurities in a three-dimensional topological superconductor, focusing on an effective model (massive Dirac Bogoliubov-de Gennes (BdG) Hamiltonian with s-wave on-site pairing) of CuxBi2Se3 with the parameter set determined by the first-principles calculation. With the use of the self-consistent T- matrix approximation for impurity scattering, we discuss the impurity-concentration dependence of the zero-energy density of states. We show that a single material variable, measuring relativistic effects in the Dirac-BdG Hamiltonian, well characterizes the numerical results. In the nonrelativistic limit, the odd-parity fully-gapped topological superconductivity is fragile against non-magnetic impurities, since this superconductivity can be mapped onto the p-wave superconductivity. On the other hand, in the ultrarelativistic limit, the superconductivity is robust against the non-magnetic impurities, since the effective model has the s-wave superconductivity. We derive the effective Hamiltonian in the both limit.

  20. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    NASA Technical Reports Server (NTRS)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For each desired property for knife fabrication and performance, there is an alloy development strategy that optimizes behavior. Although BMG knives have been demonstrated as far back as 1995, they never found commercial success because they had to be ground (which presented problems because the alloys contained beryllium), they weren't low cost (because they weren't cast to a net-shape), they were brittle (because they were made with a low-quality commercial material), and they had extremely poor corrosion resistance (because corrosion was not well-understood in these materials). Ultimately, these shortcomings prevented the widespread commercialization. In the current work, the inventors have applied more than a decade of research on BMGs from Caltech and JPL to develop a better understanding of how to make BMG knives that exhibit an optimal combination of properties, processing and cost. Alloys have been developed based in titanium (and other metals), that exhibit high toughness, high hardness, excellent corrosion resistance, no ferromagnetism, edge-retaining selfsharpening, and the ability to be cast like a plastic using commercially available casting techniques (currently used by commercial companies such as Liquidmetal Technologies and Visser Precision Casting). The inventors argue that depending on the application (diving, military, tactical, utility, etc.) there is an optimal combination of design and alloy composition. Moreover, with new casting technologies not available at the inception of these materials, net-shaped knives can be cast into complex shapes that require no aftermarket forming, except for sharpening using water-cooled polishing wheel. These combinations of discoveries seek to make low-cost BMG knives commercially viable products that have no equal among metal or ceramic knives. Current work at JPL focuses on net-shape casting of these alloys and testing their mechanical properties versus commercially available knives to demonstrate their benefits.

  1. Thermodynamic analysis of manganese

    Microsoft Academic Search

    A. Fernández Guillermet; W. Huang

    1990-01-01

    A description of the Gibbs energy of the various solid modifications of manganese at 101325 Pa has been obtained for the whole temperature range from 298 K to the melting point. The present analysis accounts for the effect of a magnetic transition in a-, ?-, and d-Mn, which is treated using the Inden-Hillert-Jarl phenomenological model for the magnetic Gibbs energy.

  2. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Identity. The color additive manganese violet is a violet pigment obtained by reacting phosphoric acid, ammonium dihydrogen...and manganese dioxide at temperatures above 450 °F. The pigment is a manganese ammonium pyrophosphate complex having the...

  3. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Identity. The color additive manganese violet is a violet pigment obtained by reacting phosphoric acid, ammonium dihydrogen...and manganese dioxide at temperatures above 450 °F. The pigment is a manganese ammonium pyrophosphate complex having the...

  4. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Identity. The color additive manganese violet is a violet pigment obtained by reacting phosphoric acid, ammonium dihydrogen...and manganese dioxide at temperatures above 450 °F. The pigment is a manganese ammonium pyrophosphate complex having the...

  5. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Identity. The color additive manganese violet is a violet pigment obtained by reacting phosphoric acid, ammonium dihydrogen...and manganese dioxide at temperatures above 450 °F. The pigment is a manganese ammonium pyrophosphate complex having the...

  6. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Identity. The color additive manganese violet is a violet pigment obtained by reacting phosphoric acid, ammonium dihydrogen...and manganese dioxide at temperatures above 450 °F. The pigment is a manganese ammonium pyrophosphate complex having the...

  7. Bacteriology of Manganese Nodules

    PubMed Central

    Ehrlich, H. L.

    1968-01-01

    A cell-free extract from Arthrobacter 37, isolated from a manganese nodule from the Atlantic Ocean, exhibited enzymatic activity which accelerated manganese accretion to synthetic Mn-Fe oxide as well as to crushed manganese nodule. The reaction required oxygen and was inhibited by HgCl2 and p-chloromercuribenzoate but not by Atebrine dihydrochloride. The rate of enzymatic action depended on the concentration of cell-free extract used. The enzymatic activity had a temperature optimum around 17.5 C and was destroyed by heating at 100 C. The amount of heat required for inactivation depended on the amount of nucleic acid in the preparation. In the cell-free extract, unlike the whole-cell preparation, peptone could not substitute for NaHCO3 in the reaction mixture. An enzyme-containing protein fraction and a nucleic acid fraction could be separated from cell extract by gel filtration, when prepared in 3% NaCl but not in seawater. The nucleic acid fraction was not required for enzymatic activity. PMID:5645405

  8. Giant spin Seebeck effect in a non-magnetic material.

    PubMed

    Jaworski, C M; Myers, R C; Johnston-Halperin, E; Heremans, J P

    2012-07-12

    The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ?25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values. PMID:22785317

  9. The Mutagenicity and Carcinogenicity of Inorganic Manganese Compounds: A Synthesis of The Evidence

    Microsoft Academic Search

    Farida Louise Assem; Philip Holmes; Leonard Stephen Levy

    2011-01-01

    Manganese (Mn), a naturally occurring element present in many foodstuffs, is an essential trace element with many biological functions. In industry, inorganic Mn compounds have a range of different applications, although the majority of Mn is used to make alloys and steel. For the general population, the major source of exposure to Mn is dietary, although drinking water may constitute

  10. The Interfacial Tension of Magnetic and Non-magnetic Dispersions

    NASA Astrophysics Data System (ADS)

    Johnson, D.

    The interfacial tension of dispersions is important in a number of applications. Some examples include, the processing of ceramics from slurries, coating of paints, slot die casting of magnetic dispersions for high density magnetic media, and protein absorption onto liquid interfaces and cell membranes in biological systems. The surface tensions of charged-stabilized silicon dioxide and titanium dioxide dispersions at different weight percents have been measured. We find that the interfacial tension first sharply decreases at low weight percents until it reaches a minimum and then increases at higher weight percents. At lower concentrations, the adsorption of particles to the interface decreases the total free energy of the system which causes a decrease in the interfacial tension of the dispersion. At higher particle concentrations, the attractive capillary forces between particles at the surface increases the amount of work it takes to deform the surface, which increases the interfacial tension of the dispersion. We have also studied the effect of acicular (rod-like shaped) particles on the interfacial tension. In particular, we have been interested in measuring the interfacial tension of acicular magnetic dispersions. Nematic liquid crystals, which consist of non-magnetic acicular particles, are known to have anisotropic surface tension that is dependent on the nematic tensor parameter. Multiple nematic phases - both prolate and oblate - are predicted for the magnetic dispersions in the presence of steady shear flow and external magnetic field. The presence of this structural order suggests exploiting the theory developed for nematic liquid crystals. In our work, we studied the surface order orientation and surface free energy of the magnetic dispersions and derived a general model of the anisotropic surface stress tensor for the magnetic dispersions. Using this model, the influences of the external magnetic field and the shear stress on the surface properties of the magnetic dispersion were also investigated. The fact that the interfacial tension of a dispersion is a function of the particle surface concentration can give rise to Marangoni-like flows caused by variations in the concentrations of adsorbed particles along the interface. When a dilute colloidal suspension of 50 ?m polyamide particles is exposed to a free interface, spontaneous flow occurs. This flow is orderly, reproducible, and shows a proportional dependence on particle concentration. The same type of flow was also observed in a silicone oil suspension. Placing a glass plate on the interface dampens the flow, eventually extinguishing it completely.

  11. Railroad rails made of bainitic steel

    Microsoft Academic Search

    V. V. Pavlov; L. A. Godik; L. V. Korneva; N. A. Kozyrev; E. P. Kuznetsov

    2007-01-01

    Results are presented from a study of the mechanical characteristics and microstructure of rails made at the Novokuznetsk\\u000a Metallurgical Combine from steel alloyed with manganese, silicon, chromium, molybdenum, and vanadium. It was established that\\u000a obtaining high strength and hardness in the steel by increasing its contents of carbon and alloying elements has an adverse\\u000a effect on the service properties of

  12. Thermodynamic and transport properties of non-magnetic particles in magnetic fluids

    E-print Network

    Tejwani, Saurabh

    2009-01-01

    Magnetic composites, obtained on associating magnetic fluid with non-magnetic particles, offer interesting opportunities in separations, assemblies and other applications, where the microstructure of the composite can be ...

  13. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 0.08 Manganese (max) 2.00 2.00 2.00 Phosphorus (max) .030 .030 .030 Sulphur (max) .030... Rephosphorized steels not subject to check analysis for phosphorus. (c) Identification of material. Materials must...

  14. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 0.08 Manganese (max) 2.00 2.00 2.00 Phosphorus (max) .030 .030 .030 Sulphur (max) .030... Rephosphorized steels not subject to check analysis for phosphorus. (c) Identification of material. Materials must...

  15. 49 CFR 178.58 - Specification 4DA welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Carbon 0.28/0.33. Manganese 0.40/0.60. Phosphorus 0.040 max. Sulfur 0.040 max. Silicon 0.15... Rephosphorized steels not subject to check analysis for phosphorus. (c) Identification of material. Materials...

  16. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 0.08 Manganese (max) 2.00 2.00 2.00 Phosphorus (max) .030 .030 .030 Sulphur (max) .030... Rephosphorized steels not subject to check analysis for phosphorus. (c) Identification of material. Materials must...

  17. Structure of steel G13L with silicon

    Microsoft Academic Search

    V. M. Krivospitskii; A. S. Nikonenko; V. F. Kharitonova

    1975-01-01

    1.Silicon raises the temperature at which carbide is formed in manganese austenitic steels.2.Silicon changes the microstructure obtained after tempering. Raising the silicon content of steel G13L changes the microstructure from acicular to globular.3.Silicon inhibits the ??a transformation. The initial decomposition temperature of austenite increases with the silicon content, which affects the mechanical properties of austenitic steel. The beginning of the

  18. Autogenous laser welding of stainless steel to free-cutting steel for the manufacture of hydraulic valves

    Microsoft Academic Search

    Zhang Li; G Fontana

    1998-01-01

    The hydraulic valves referred to in this study are made of AISI304L non-magnetic stainless steel and AISI12L13 free-cutting steel tubular parts, which make up the main valve cylinder. The valves must have mechanical properties of a high level in order to be able to stand up to the demanding operating pressure cycles. In the final assembly, the valve cylinder, with

  19. Manganese metallurgy review. Part II: Manganese separation and recovery from solution

    Microsoft Academic Search

    Wensheng Zhang; Chu Yong Cheng

    2007-01-01

    Various methods for manganese separation and recovery from solution are reviewed, which are potentially applicable to leach solutions of secondary manganese sources, particularly nickel laterite waste effluents. The main methods include solvent extraction, sulfide precipitation, ion exchange, hydroxide precipitation and oxidative precipitation. These methods are briefly compared and assessed for both purification of manganese solutions and recovery of manganese from

  20. Health and environmental testing of manganese exhaust products from use of methylcyclopentadienyl manganese tricarbonyl in gasoline

    Microsoft Academic Search

    G. D. Pfeifer; J. M. Roper; D. Dorman; D. R. Lynam

    2004-01-01

    This paper reviews recent research on the environmental effects of methylcyclopentadienyl manganese tricarbonyl (MMT), personal exposures to airborne Mn as a result of MMT use, chemical characterization of the manganese particulates emitted from the tailpipe and progress in developing a (PBPK) model for manganese in rodents.Recent studies show that manganese is emitted as a mixture of compounds with an average

  1. Manganese deficiency in sugar beet and the incorporation of manganese in the coating of pelleted seed

    Microsoft Academic Search

    R. F. Farley; A. P. Draycott

    1978-01-01

    Summary A laboratory study, three glasshouse tests and eight field experiments on commercial farms in East Anglia during 1972 to 1974 tested the effect of incorporating manganese in the coating of pelleted seed on the manganese nutrition and yield of sugar beet. The pelleting material readily absorbed manganese from solution but most of the manganese was held in plant-available forms.

  2. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors

    PubMed Central

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J.; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F.; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V.

    2015-01-01

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102?nm2 cross-section. The impurities suppress superconductivity in a three-dimensional ‘Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ?1.34?nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities. PMID:26139568

  3. Biomarkers of Manganese Intoxication

    PubMed Central

    Zheng, Wei; Fu, Sherleen X.; Dydak, Ulrike; Cowan, Dallas M.

    2010-01-01

    Manganese (Mn), upon absorption, is primarily sequestered in tissue and intracellular compartments. For this reason, blood Mn concentration does not always accurately reflect Mn concentration in the targeted tissue, particularly in the brain. The discrepancy between Mn concentrations in tissue or intracellular components means that blood Mn is a poor biomarker of Mn exposure or toxicity under many conditions and that other biomarkers must be established. For group comparisons of active workers, blood Mn has some utility for distinguishing exposed from unexposed subjects, although the large variability in mean values renders it insensitive for discriminating one individual from the rest of the study population. Mn exposure is known to alter iron (Fe) homeostasis. The Mn/Fe ratio (MIR) in plasma or erythrocytes reflects not only steady-state concentrations of Mn or Fe in tested individuals, but also a biological response (altered Fe homeostasis) to Mn exposure. Recent human studies support the potential value for using MIR to distinguish individuals with Mn exposure. Additionally, magnetic resonance imaging (MRI), in combination with noninvasive assessment of ?-aminobutyric acid (GABA) by magnetic resonance spectroscopy (MRS), provides convincing evidence of Mn exposure, even without clinical symptoms of Mn intoxication. For subjects with long-term, low-dose Mn exposure or for those exposed in the past but not the present, neither blood Mn nor MRI provides a confident distinction for Mn exposure or intoxication. While plasma or erythrocyte MIR is more likely a sensitive measure, the cut-off values for MIR among the general population need to be further tested and established. Considering the large accumulation of Mn in bone, developing an X-ray fluorescence spectroscopy or neutron-based spectroscopy method may create yet another novel non-invasive tool for assessing Mn exposure and toxicity. PMID:20946915

  4. Influence of essential elements on manganese intoxication

    SciTech Connect

    Khandelwal, S.; Ashquin, M.; Tandon, S.K.

    1984-01-01

    With a view to explore the influence of essential metals in manganese intoxication, the effect of calcium, iron or zinc supplementation on the uptake of manganese and on the activity of manganese sensitive enzymes, succinic dehydrogenase and cytochrome oxidase in brain and liver of rat was investigated. The choice of the two mitochondrial enzymes was based on the fact that the mitochondria are the chief site of manganese accumulation and their activity in brain, liver and blood of rats is significantly influenced by manganese.

  5. Temperature dependence of electroluminescence and I– V characteristics of ferromagnetic\\/non-magnetic semiconductor pn junctions

    Microsoft Academic Search

    I. Arata; Y. Ohno; F. Matsukura; H. Ohno

    2001-01-01

    We investigated the temperature dependence of the electroluminescence and I–V characteristics of hybrid ferromagnetic\\/non-magnetic semiconductor pn junction light emitting diodes, which is used for spin-injection experiments reported earlier. The observed temperature dependence is found to be reproduced by a reference sample of non-magnetic p-GaAs\\/(In,Ga)As\\/n-GaAs with an undoped (Al,Ga)As spacer layer. This suggests the existence of potential barrier at the (Ga,Mn)As\\/GaAs

  6. Non-magnetic nano-composites for optical and infrared negative refraction index media

    E-print Network

    Robyn Wangberg; Justin Elser; Evgenii E. Narimanov; Viktor A. Podolskiy

    2005-06-27

    We develop an approach to use nanostructured plasmonic materials as a non-magnetic negative-refractive index system at optical and near-infrared frequencies. In contrast to conventional negative refraction materials, our design does not require periodicity and thus is highly tolerant to fabrication defects. Moreover, since the proposed materials are intrinsically non-magnetic, their performance is not limited to proximity of a resonance so that the resulting structure has relatively low loss. We develop the analytical description of the relevant electromagnetic phenomena and justify our analytic results via numerical solutions of Maxwell equations.

  7. Thermal and magnetic properties of manganese oxides

    NASA Astrophysics Data System (ADS)

    Smolyaninova, Vera Nikolaevna

    This thesis reports a study of the thermal, magnetic and transport properties of perovskite manganese oxides A1-xBxMnO3 (A = La, Nd, and Pr; B = Ca, Ba, and Sr). The ferromagnetic (FM) metallic (low x) and the charge-ordered (CO) (high x) doping regimes were studied in order to better understand the complex behavior of these materials. In the metallic doping range the low temperature magnetization was found to be in agreement with the Bloch law for ferromagnetic spin waves, and the spin-wave stiffness was determined. Important parameters such as the Debye temperature and the effective mass of the charge carriers were determined from low temperature specific heat experiments. The effective mass of the charge carriers was found to be 2--4 times heavier than the mass obtained from band structure calculations suggesting an important role of electron-phonon interactions in these materials. In order to better understand the nature of the metal-insulator transition at the ferromagnetic TC the resistivity and magnetization of epitaxial thin films of La0.67Ca 0.33MnO3 and Nd0.7Sr0.3MnO3 were studied. It was found that the behavior of the resistivity and magnetization near TC is inconsistent with Anderson localization as proposed by several theories. Various compositions of charge-ordered La1-xCaxMnO3 and Pr1-xCa1-xMnO 3 were studied to better understand the CO transition and its ground state. From powder neutron diffraction measurements we found that the CO antiferromagnetic (AFM) and ferromagnetic metallic phases coexist at low temperatures. Charge ordered Pr1-xCaxMnO3 and La1-xCax MnO3 (x ? 0.5) were found to have an anomalous excess specific heat ( C') at low temperatures (T < 20 K). This C' contribution has a temperature dependence consistent with non-magnetic excitations with a dispersion relation e = Delta' + Bq2. Surprisingly, it was found that a magnetic field sufficient to induce the transition from the insulating CO (and AFM) state to the metallic FM state is not sufficient to eliminate the C' contribution to the specific heat. The possible origin of these excitations and their relation to the CO ground state is discussed.

  8. Synthesis, characterization, optical and sensing property of manganese oxide nanoparticles

    SciTech Connect

    Manigandan, R.; Suresh, R.; Giribabu, K.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India); Vijayalakshmi, L. [Annai Veilankanni's College for Women (Arts and Science), Saidapet, Chennai 600015 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2014-01-28

    Manganese oxide nanoparticles were prepared by thermal decomposition of manganese oxalate. Manganese oxalate was synthesized by reacting 1:1 mole ratio of manganese acetate and ammonium oxalate along with sodium dodecyl sulfate (SDS). The structural characterization of manganese oxalate and manganese oxide nanoparticles was analyzed by XRD. The XRD spectrum confirms the crystal structure of the manganese oxide and manganese oxalate. In addition, the average grain size, lattice parameter values were also calculated using XRD spectrum. Moreover, the diffraction peaks were broadened due to the smaller size of the particle. The band gap of manganese oxide was calculated from optical absorption, which was carried out by DRS UV-Visible spectroscopy. The morphology of manganese oxide nanoparticles was analyzed by SEM images. The FT-IR analysis confirms the formation of the manganese oxide from manganese oxalate nanoparticles. The electrochemical sensing behavior of manganese oxide nanoparticles were investigated using hydrogen peroxide by cyclic voltammetry.

  9. Aspiration from the vitreous of a non-magnetic foreign body

    Microsoft Academic Search

    H. B. Chawla; J. A. Coleiro; F. Jonasson

    1978-01-01

    A non-magnetic vitreal foreign body was aspirated from over the macula through the pars plana. The surgeon guided a blunt needle towards the foreign body while watching both with the binicular indirect ophthalmoscope. His assistant's tentative suction movements with an attached syringe drew the foreign body up into the needle without risking a retinal perforation. Visual recovery was complete. It

  10. Development of microalloyed high-carbon steels for plough disks

    NASA Astrophysics Data System (ADS)

    Crnkovic, O. R.; Bastian, F. L.

    1996-12-01

    Plough disks are often made of high-carbon steels with small additions of chromium (0.40 to 0.60%), in the as-quenched and tempered condition. As a consequence, they combine wear resistance with the tensile, fatigue, and impact strength necessary to withstand extremely adverse work conditions. In an effort to produce steels for this use with improved mechanical properties, four different steel compositions, all microalloyed with niobium, were produced for the present work. Two steels kept the basic chromium content of the commercial alloy (0.40 to 0.60%), while this element was replaced with manganese in the other two steels. The chromium and manganese steels were produced with two levels of niobium. The Jominy hardenability, tensile properties, and impact and wear resistance of these materials were evaluated. A microstructural characterization was also performed. The results show that the developed steels can have the required hardness and strength levels. The high-niobium steels showed the best wear resistance but the poorest impact toughness. The wear resistance of the low-niobium steels was slightly higher and the impact toughness slightly lower than in the commercial alloy. The low-niobium steels show potential for commercial use.

  11. Corrosion Behavior of High Nitrogen Nickel-Free Fe-16Cr-Mn-Mo-N Stainless Steels

    NASA Astrophysics Data System (ADS)

    Chao, K. L.; Liao, H. Y.; Shyue, J. J.; Lian, S. S.

    2014-04-01

    The purpose of the current study is to develop austenitic nickel-free stainless steels with lower chromium content and higher manganese and nitrogen contents. In order to prevent nickel-induced skin allergy, cobalt, manganese, and nitrogen were used to substitute nickel in the designed steel. Our results demonstrated that manganese content greater than 14 wt pct results in a structure that is in full austenite phase. The manganese content appears to increase the solubility of nitrogen; however, a lower corrosion potential was found in steel with high manganese content. Molybdenum appears to be able to increase the pitting potential. The effects of Cr, Mn, Mo, and N on corrosion behavior of Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels were evaluated with potentiodynamic tests and XPS surface analysis. The results reveal that anodic current and pits formation of the Fe-16Cr-2Co-Mn-Mo-N high nitrogen stainless steels were smaller than those of lower manganese and nitrogen content stainless steel.

  12. Impact of dietary manganese concentration on status criteria to determine manganese requirement in piglets.

    PubMed

    Pallauf, J; Kauer, C; Most, E; Habicht, S D; Moch, J

    2012-12-01

    The Mn requirement for pigs is not well established. This study aimed to find criteria for assessing growing piglet supply status for Mn and to determine whether the current Mn recommendations meet the requirements for piglets. Thirty-six weaned male castrated 27-day-old piglets (7.24?±?0.69?kg) were randomized into six groups of six piglets each and housed individually in stainless steel metabolic cages for 42?days. The piglets were fed a diet based on skimmed milk powder and corn starch with increasing Mn concentrations (0.24; 2; 4; 8; 16; or 32?mg?Mn/kg diet as-fed). In week 6, Mn0.24 led to reduced feed intake (p?Manganese concentrations in blood, liver, kidney, lung, heart, phalanx proximalis, pancreas and skeletal muscle were influenced by the dietary Mn supply (p?Manganese concentrations in the liver, kidney and phalanx proximalis seem to be suitable biomarkers for Mn status. A 4?mg/kg dietary Mn concentration recommended by NRC (1998, Nutrient Requirements of Swine. National Academy Press, Washington DC.) did not fulfil piglet requirements. Under the conditions investigated, 16?mg?Mn/kg diet were necessary to reach a plateau in specific enzyme activity and Mn concentration in organs. PMID:21883497

  13. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

  14. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

  15. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

  16. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

  17. Methylcyclopentadienyl Manganese Tricarbonyl: Effect on Manganese Emissions from Vehicles on the Road

    Microsoft Academic Search

    William R. Pierson; Douglas E. McKee; Wanda W. Brachaczek; James W. Butler

    1978-01-01

    This note describes some measurements of manganese concentrations and manganese emission rates, categorized as to vehicle type, from cars and trucks at two tunnels on the Pennsylvania Turnpike. These measurements were made during the period that methylcyclopentadienyl manganese tricarbonyl (MMT) came into use as an alternative to organo-lead compounds for improving combustion in gasoline engines.

  18. Negative impact of manganese on honeybee foraging.

    PubMed

    Søvik, Eirik; Perry, Clint J; LaMora, Angie; Barron, Andrew B; Ben-Shahar, Yehuda

    2015-03-01

    Anthropogenic accumulation of metals such as manganese is a well-established health risk factor for vertebrates. By contrast, the long-term impact of these contaminants on invertebrates is mostly unknown. Here, we demonstrate that manganese ingestion alters brain biogenic amine levels in honeybees and fruit flies. Furthermore, we show that manganese exposure negatively affects foraging behaviour in the honeybee, an economically important pollinator. Our findings indicate that in addition to its direct impact on human health, the common industrial contaminant manganese might also have indirect environmental and economical impacts via the modulation of neuronal and behavioural functions in economically important insects. PMID:25808001

  19. Analytical electron microscopy of stainless steel weld metal

    Microsoft Academic Search

    Lyman

    1979-01-01

    The technique of analytical electron microscopy in a Scanning Transmission Electron Microscope (STEM) fitted with an x-ray spectrometer is described. This high spatial resolution microanalysis technique is applied to duplex Type 304L stainless steel weld metal. Small inclusions in these steels may be either iron-rich or manganese-rich silicates and may contain small amounts of elements not listed in the normal

  20. Heating steels in vacuum

    SciTech Connect

    Marmer, E.N.

    1983-03-01

    It is recommended that high-strength and corrosion-resistant steels be heated in an electric vacuum furnace. Absence of oxidation and decarburization, decrease in the deformation of the part, increase in service life, plus safety, and nontoxicity in the shop, are cited as advantages. Annealing, carburizing, hardening, brazing, and sintering--all detailed-can be more efficiently accomplished in vacuum heating. As vacuum heating requires certain surface conditions, the compositions of residual mediums is studied. The microrelief and surface finish obtained after vacuum heating is determined. Annealing in a vacuum is compared to annealing in air, a depletion in manganese indicating a greater savings by use of vacuum. Ductility is also tested. The gas of special purity nitrogen is recommended for best results. In general, then, use of electric vacuum furnaces is recommended.

  1. Effect of magnetic and non-magnetic substitution in topological Kondo insulator SmB6

    NASA Astrophysics Data System (ADS)

    Wang, Xiangfeng; Nakajima, Yasuyuki; Saha, Shanta; Paglione, Johnpierre; Sonier, Jeff; Johnpierre Paglione Team, Prof.; Jeff Sonier Team, Prof.

    2015-03-01

    The topological Kondo Insulator SmB6 is believed be the first realization of a topological insulator with true bulk insulating properties that coexist with a robust conducting surface state that mounting evidence suggests is non-trivial. Here we report of a systemic study of the magnetic and non-magnetic doping effect TKI SmB6, in particular the effect of iron inclusion as well as both magnetic and non-magnetic rare earth substitution in Sm1-xRxB6. We will present our careful investigations of crystal structure, transport properties and magnetization, as well as muon spin rotation studies that together suggest a very profound effect on both the bulk and surface state properties.

  2. Iron and nitrogen self-diffusion in non-magnetic iron nitrides

    SciTech Connect

    Gupta, Mukul; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452 001 (India); Gupta, Rachana [Institute of Engineering and Technology, Khandwa Road, Devi Ahilya Vishwavidyalaya, Indore 452 017 (India); Stahn, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Horisberger, M. [Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Wildes, A. [Institut Laue-Langevin, rue des Martyrs, 38042 Grenoble Cedex (France); Tayal, Akhil

    2011-12-15

    The self-diffusion of iron and nitrogen is measured in nm range non-magnetic iron nitride thin films. Two non-magnetic iron nitrides, Fe{sub 2.23}N and FeN, were studied using neutron reflectivity. Neutron reflectivity with a depth resolution in the sub-nm range has a different scattering cross section for isotopes, providing a unique opportunity to measure very small diffusivities. The isotope heterostructure in thin film multilayers [Fe-N/{sup 57}Fe-N]{sub 10} and [Fe-N/Fe-{sup 15}N]{sub 10} were prepared using magnetron sputtering. It was observed that nitrogen diffuses slower than iron although the atomic size of iron is larger than that of nitrogen. It was found that a significantly larger group of N atoms participates in the diffusion process than of Fe, making N diffusion slower than that of Fe.

  3. Sensitivity of a 3D fully-gapped topological superconductor to non-magnetic impurities

    NASA Astrophysics Data System (ADS)

    Ota, Yukihiro; Nagai, Yuki; Machida, Masahiko

    2015-03-01

    Topological superconductors (TSC) are notable materials, owing to the mathematical curiosity and the application potential. The bulk TSC can emerge by copper intercalation into topological insulator Bi2Se3. In this paper, we theoretically study the non-magnetic impurity effects in the mean-field model of CuxBi2Se3, focusing on the odd-parity fully-gapped superconducting state. Calculating the density of states with a self-consistent T-matrix approach, we test the presence of mid-gap states, leading to pair-breaking effects. Remarkably, the sensitivity to non-magnetic impurities strongly depend on a normal-state dispersion character, i.e., either non-relativistic or relativistic dispersion relations. We show unification picture for understanding this intriguing result, deriving a low-energy effective superconducting theory.

  4. Analysis on the Reflection Characteristic of Electromagnetic Wave Incidence in Closed Non-Magnetized Plasma

    Microsoft Academic Search

    L.-X. Ma; H. Zhang; C.-X. Zhang

    2008-01-01

    The reflection characteristic of EM-wave (Electromagnetic Wave) incidence in non-magnetized closed plasma with uniformed multi-layer and outer envelope is discussed accordingly to plasma stealth technology applying practically to aircrafts. Based on wave impedance matching principle, the reflection coefficient of the composed structure including outer envelope dielectric and plasma plus metal plate is deduced and completed. Furthermore, the reflection loss is

  5. FMR study of magnetic nanoparticles embedded in non-magnetic matrix

    Microsoft Academic Search

    N. Guskos; E. A. Anagnostakis; A. Guskos

    Purpose: The aim of this review is recapitulating the FMR study of low concentration of magnetic nanoparticles in non-magnetic matrices. Design\\/methodology\\/approach: Magnetic nanoparticles exhibit a variety of anomalous magnetic properties and they could be used for forming low concentration in different matrices. This way, they are being found to be allowing for effectively novel applications of FMR (ferromagnetic resonance) for

  6. Aspiration from the vitreous of a non-magnetic foreign body.

    PubMed Central

    Chawla, H. B.; Coleiro, J. A.; Jonasson, F.

    1978-01-01

    A non-magnetic vitreal foreign body was aspirated from over the macula through the pars plana. The surgeon guided a blunt needle towards the foreign body while watching both with the binicular indirect ophthalmoscope. His assistant's tentative suction movements with an attached syringe drew the foreign body up into the needle without risking a retinal perforation. Visual recovery was complete. It is suggested that aspiration might be the procedure of choice for such small visible intraocular fragments. Images PMID:718819

  7. Comparative pneumotoxicity of cyclopentadienyl manganese tricarbonyl and methylcyclopentadienyl manganese tricarbonyl.

    PubMed

    Clay, R J; Morris, J B

    1989-05-01

    The acute pneumotoxic effects of cyclopentadienyl manganese tricarbonyl (CMT) and methylcyclopentadienyl manganese tricarbonyl (MMT) were compared to delineate the role of the methyl side chain in the toxicity of these organomanganese compounds and to further our understanding of the mechanisms by which these compounds act. Specifically, lung manganese (Mn) burdens and the pneumotoxic response, as measured by bronchoalveolar lavage parameters, were determined in male Sprague-Dawley rats 24 hr after sc administration of 0.5, 1.0, or 2.5 mg Mn/kg as CMT or MMT. The pneumotoxic response to either compound was characterized by large increases in lavage albumin and protein content with smaller increases in lactate dehydrogenase levels. CMT was approximately twice as potent as MMT. This difference in potency may be due to methyl side chain oxidation, a metabolic detoxification pathway unavailable to CMT. Lung Mn content was significantly elevated after treatment with either CMT or MMT. Heptane extraction studies revealed that Mn was accumulated in a nonlipid soluble form, suggesting the accumulation of metabolites rather than heptane soluble parent MMT or CMT. A strong correlation between pulmonary Mn content and toxicity was observed, suggesting a causal relationship between the accumulation of CMT or MMT metabolites and toxicity. Piperonyl butoxide diminished both the pneumotoxicity and Mn accumulation resulting from CMT or MMT, suggesting both phenomena are due to monooxygenase metabolites. Pulmonary nonprotein sulfhydryl (NPSH) levels were increased twofold 24 hr after administration of either CMT or MMT. Depletion of NPSH was not observed 1.5 or 6 hr after administration. The mechanisms of this response are unclear but may be due to the metabolism of CMT or MMT to unstable compounds which release inorganic Mn within pulmonary cells. PMID:2718172

  8. Characterization of the Weld Regions within Duplex Stainless Steels using Magnetic Force Microscopy

    Microsoft Academic Search

    B. Gideon; L. Ward; K. Short

    Standard metallography and optical microscopy are well established techniques for the characterization of duplex stainless steels (DSS), which consist of approximately 50% ferrite and 50% austenite. Recently, the use of atomic and magnetic force microscopies (AFM and MFM respectively) have been employed to differentiate between magnetic and non magnetic phases in materials. Such techniques would be valuable to identify different

  9. Electric resistance welded steels for normalized N-80 oil and gas well tubulars

    Microsoft Academic Search

    D. L. Spon seller; T. B. Cox; E. J. Vineberg

    1984-01-01

    This paper reports the development and successful commercialization of a manganese-molybdenum steel for use in the production of normalized electric resistance welded N-80 casing and tubing. The new steel, nominally a 0.33C, 1.4Mn, 0.23Mo grade, is easily formed and readily welded into pipe. The properties of the new steel are remarkably independent of the coiling temperature on the hot strip

  10. Drinking Water Problems: Iron and Manganese 

    E-print Network

    Dozier, Monty; McFarland, Mark L.

    2004-02-20

    Iron and manganese can give water an unpleasant taste, odor and color. In this publication you'll learn how to know whether your water contains iron or manganese and how to eliminate these contaminants with various treatment methods such as aeration...

  11. The magnetism of metallic manganese alloys

    SciTech Connect

    Holden, T.M. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada)); Mikke, K. (Institute of Atomic Energy, Otwock-Swierk (Poland)); Fawcett, E. (Toronto Univ., ON (Canada)); Fernandez-Baca, J.A. (Oak Ridge National Lab., TN (United States))

    1992-01-01

    The magnetic excitations in antiferromagnetic manganese-copper and manganese-iron alloys are characterized by high spin-wave velocities, and energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above T[sub N] as well as magnetoelastic distortions below T[sub N]. The theoretical explanation of these effects is reviewed.

  12. The magnetism of metallic manganese alloys

    SciTech Connect

    Holden, T.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada); Mikke, K. [Institute of Atomic Energy, Otwock-Swierk (Poland); Fawcett, E. [Toronto Univ., ON (Canada); Fernandez-Baca, J.A. [Oak Ridge National Lab., TN (United States)

    1992-12-31

    The magnetic excitations in antiferromagnetic manganese-copper and manganese-iron alloys are characterized by high spin-wave velocities, and energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above T{sub N} as well as magnetoelastic distortions below T{sub N}. The theoretical explanation of these effects is reviewed.

  13. Original article Intestinal transfer of manganese

    E-print Network

    Paris-Sud XI, Université de

    Original article Intestinal transfer of manganese: resemblance to and competition with calcium Y of calcium, phosphate and the sugars lactose and sorbitol on the intestinal absorption of manganese were by this high calcium concentration. Intestinal alkaline phosphatase activity was rapidly stimulated by Mn

  14. Austenite decomposition in ternary manganese, molybdenum and tungsten steels

    NASA Astrophysics Data System (ADS)

    Hackenberg, Robert Errol

    A survey of austenite decomposition in Fe-(0.1, 0.2)C-(3, 4.2)Mn has revealed kinetic and morphological transitions which take place at substantial undercoolings below the paraequilibrium Ae3 temperature. An unusually long interval of transformation stasis was found in Fe-0.1C-3Mn, during which time the ferrite was free of carbides. A nodular product containing rod particles was observed in several of these alloys. The grain boundary bainite (GBB) and twin boundary bainite (TBB) morphologies at the bay in Fe-0.24C-4Mo were significantly more complex than previously assumed, with differing arrangements of bainite subunits; their thickening rates also differed. TEM revealed 10 nm steps at the bainite-austenite interfaces in GBB. Mo enrichment was found within GBB-austenite interfaces and extended ˜10 nm into the austenite. The M2C carbides are always enriched in Mo, possessing a non-equilibrium Mo content at earlier reaction times. The energies stored in the ferrite-carbide interfacial area and in carbides possessing non-equilibrium Fe/Mo ratios were considered to reduce the driving force for diffusion by up to 20%. GBB and TBB were found at and above the bay in Fe-0.3C-6.3W, while the bainite formed below the bay consisted of elongated subunits. M6C was found at all temperatures, while M2C was found only below the bay, both of which exhibited W partition. A dark-etching constituent of very high carbide density transformed the remaining pools of austenite at the late stages of reaction, a result consistent with the level of carbon in austenite rising with time. Transitions in carbide morphology were explored in Fe-0.2C-63W. At lower reaction temperatures, M6C precipitates with ferrite. At higher temperatures the cellular precipitation of quasilamellar M 6C in austenite occurs, and is considered to take place inside the ferrite + austenite + M6C three-phase field. The austenite inside the quasilamellar carbide nodules reverts to ferrite at long times, indicating a non-equilibrium transformation path.

  15. Manganese borohydride; synthesis and characterization.

    PubMed

    Richter, Bo; Ravnsbæk, Dorthe B; Tumanov, Nikolay; Filinchuk, Yaroslav; Jensen, Torben R

    2015-03-01

    Solvent-based synthesis and characterization of ?-Mn(BH4)2 and a new nanoporous polymorph of manganese borohydride, ?-Mn(BH4)2, via a new solvate precursor, Mn(BH4)2·1/2S(CH3)2, is presented. Manganese chloride is reacted with lithium borohydride in a toluene/dimethylsulfide mixture at room temperature, which yields halide and solvent-free manganese borohydride after extraction with dimethylsulfide (DMS) and subsequent removal of residual solvent. This work constitutes the first example of establishing a successful, reproducible solvent-based synthesis route for a pure, crystalline, stable transition metal borohydride. The new polymorph, ?-Mn(BH4)2, is shown to be the manganese counterpart of the zeolite-like compound, ?-Mg(BH4)2 (cubic, a = 16.209(1) Å, space group Id3?a). It is verified that large pores (diameter > 6.0 Å) exist in this structure. The solvate, Mn(BH4)2·1/2S(CH3)2, is subsequently shown to be the analogue of Mg(BH4)2·1/2S(CH3)2. As the structural analogies between Mg(BH4)2 and Mn(BH4)2 became evident a new polymorph of Mg(BH4)2 was identified and termed ?-Mg(BH4)2. ?-Mg(BH4)2 is the structural counterpart of ?-Mn(BH4)2. All synthesis products are characterized employing synchrotron radiation-powder X-ray diffraction, infrared spectroscopy and thermogravimetric analysis in combination with mass spectroscopy. Thermal analysis reveals the decomposition of Mn(BH4)2 to occur at 160 °C, accompanied by a mass loss of 14.8 wt%. A small quantity of the desorbed gaseous species is identified as diborane (?(m)(Mn(BH4)2) = 9.5 wt% H2), while the remaining majority is found to be hydrogen. PMID:25611294

  16. Dependence of the magnetization on the interface morphology in ultra-thin magnetic\\/non-magnetic films: Monte Carlo approach

    Microsoft Academic Search

    A. Razouk; M. Sahlaoui; M. Sajieddine

    2009-01-01

    Using Monte Carlo simulations, we have studied the dependence of magnetic properties on interface morphology in magnetic\\/non-magnetic (M\\/NM) multilayers. Our aim is to relate macroscopic magnetic properties of the multilayers to their concentration profile at the interface. Our model consists of an alternate staking of magnetic and non-magnetic layers with disordered interfaces. We have considered different concentration and the existence

  17. Medium Mn TRIP-assisted steels J.H. Ryu, M.S. Joo, H.S. Yang,

    E-print Network

    Cambridge, University of

    casting - interaction with refractory (H-Al alloy) · Reduced Al in alloy design - reduced C or Mn;1. Research Background 2. Medium Mn TRIP-assisted steels - Effect of aluminum on mechanical performance 3. C%) #12;Medium manganese TRIP steels ·0.1C-6Mn based alloy introduced by R.L Miller in 1972 ·Annealing

  18. Manganese in Texas Soils and its Relation to Crops. 

    E-print Network

    Carlyle, E. C. (Elmer Cardinal)

    1931-01-01

    , and by Schreiner and Damison (15) in testing for deficiency of manganese in the glade soils of Florida. 10 BULLETIN NO. 432. TEXAS AGRICULTURAL EXPERIMENT STATION Method for Pot Experiments Glazed earthenware pots of two gallons capacity were used in this work... pouncls. Rye without manganese bage ldecl lfate I nn cal- nat- )en- ?nn- ob- eat, ~eri- sul- tin : MANGANESE IN TEXAS SOILS AND ITS RELATION TO CROPS 9 yieldecl 3456 pouncls per acre; with manganese, 3424 pounds. Corn without manganese...

  19. [Tongue play and manganese deficiency in dairy cattle].

    PubMed

    Karatzias, H; Roubies, N; Polizopoulou, Z; Papasteriades, A

    1995-09-01

    The present paper discusses "tongue rolling" observed in dairy cattle farms of a region in northern Greece associated with manganese deficiency. In these animals total body manganese status was evaluated by determining hair, as well as feed manganese content. Cows exhibiting tongue rolling had significantly lower hair manganese content, compared to non-tongue rolling control animals from other farms; in addition, feedstuff analysis demonstrated that manganese and inorganic phosphorus intake of affected cows was also significantly lower. PMID:8591770

  20. By Thomas S. Jones Manganese (Mn) is essential to iron and silicomanganese increased about 7%. consisted of, in tons, natural battery-grade ore,

    E-print Network

    Torgersen, Christian

    about 7%. consisted of, in tons, natural battery-grade ore, steel production by virtue of its sulfur aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature of manganese consumption in batteries was denoted by the expansion on schedule of domestic capacity for production

  1. Chronic manganese poisoning: A neuropathological study with determination of manganese distribution in the brain

    Microsoft Academic Search

    M. Yamada; S. Ohno; I. Okayasu; R. Okeda; S. Hatakeyama; H. Watanabe; K. Ushio; H. Tsukagoshi

    1986-01-01

    An autopsy case of a 52-year-old man suffering from chronic manganese poisoning (CMP) is reported with determination of the manganese distribution in the brain. The patient had been working in a manganese ore crushing plant since 1965. In 1967 he began to complain of difficulties in walking and diminished libido. Later, he developed various neuro-psychiatric symptoms including euphoria, emotional incontinence,

  2. Development of a Non-Magnetic Inertial Sensor for Vibration Stabilization in a Linear Collider

    SciTech Connect

    Frisch, Josef; Decker, Valentin; Doyle, Eric; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Seryi, Andrei; /SLAC; Chang, Allison; Partridge, Richard; /Brown U.

    2006-09-01

    One of the options for controlling vibration of the final focus magnets in a linear collider is to use active feedback based on accelerometers. While commercial geophysics sensors have noise performance that substantially exceeds the requirements for a linear collider, they are physically large, and cannot operate in the strong magnetic field of the detector. Conventional nonmagnetic sensors have excessive noise for this application. We report on the development of a non-magnetic inertial sensor, and on a novel commercial sensor both of which have demonstrated the required noise levels for this application.

  3. Analysis of manganese particulates from automotive decomposition of methylcyclopentadienyl manganese tricarbonyl

    NASA Astrophysics Data System (ADS)

    Colmenares, C.; Deutsch, Steven; Evans, Cheryl; Nelson, A. J.; Terminello, Louis J.; Reynolds, John G.; Roos, Joseph W.; Smith, Isaac L.

    1999-10-01

    Particulates have been collected and analyzed from automotive vehicles operating on fuel containing the organometallic antiknock additive methylcyclopentadienyl manganese tricarbonyl. Electron spectroscopy for chemical analysis and L-edge X-ray absorption spectroscopy were used to study and identify the manganese species present in these emitted particulates. Results show that respirable size particulates with a mass median aerodynamic diameter of 2.5 ?m or less (PM 2.5) in vehicle exhaust contain manganese primarily in the form of a manganese phosphate and/or sulfate.

  4. Hot Coal Gas Desulfurization with manganese-based sorbents. Second [quarterly] technical report, December 1, 1992--March 1, 1993

    SciTech Connect

    Hepworth, M.T.

    1993-03-01

    At present, the focus of work being performed on Hot Coal Gas Desulfurization is primarily in the use of zinc ferrite and zinc titanate sorbents; however studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan indicate that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a preferable alternative to zinc-based sorbents. A significant domestic source of manganese in Minnesota is being explored for an in situ leach process which has potential for producing large tonnages of solutions which may be ideal for precipitation and recovery of pure manganese as a carbonate in a reactive form. In the current program the following studies will be addressed: Preparation of manganese sorbent pellets and characterization tests on pellets for strength and surface area; analysis of the thermodynamics and kinetics of sulfur removal from hot fuel gases by individual sorbent pellets (loading tests) by thermogravimetric testing; regeneration tests via TGA on individual sorbent pellets by oxidation; and bench-scale testing on sorbent beds in a two-inch diameter reactor. The developed information will be of value to METC in its determination of whether or not a manganese-based regenerable sorbent holds real promise for sulfur cleanup of hot fuel gases. This information is necessary prior to pilot-scale testing leading to commercial development is undertaken.

  5. A manganese oxidation model for rivers

    SciTech Connect

    Hess, G.W. (Geological Survey, Doraville, GA (United States)); Kim, Byung R. (General Motors Research Lab., Warren, MI (United States)); Roberts, P.J.W. (Georgia Inst. of Tech, Atlanta (United States))

    1989-04-01

    The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the los pH conditions, or their combinations.

  6. HEALTH ASSESSMENT DOCUMENT FOR MANGANESE. FINAL REPORT

    EPA Science Inventory

    The document evaluates data on occurrence, sources, and transport of manganese in the environment and data on metabolism, pharmacokinetics, laboratory toxicological and epidemiologic studies to determine the nature and dose response relationship of potential health effects on hum...

  7. Methylcyclopentadienyl manganese tricarbonyl (MMT) in petrol: the toxicological issues.

    PubMed

    Abbott, P J

    1987-12-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT), when used as an octane improver in petrol, leads to increased airborne levels of manganese in the form of Mn3O4. The potential health effects of increased airborne manganese are considered in this paper. Manganese, unlike lead which it can replace in petrol, is a normal and essential component of the human diet and the intake from airborne manganese is slight by comparison to the normal dietary intake. The major toxicological effects of manganese, observed after long occupational exposure, are on the lung (manganese pneumonia) and the central nervous system (manganism). The small increase in airborne manganese from the use of MMT in petrol is 3-4 orders of magnitude lower than the level required to produce toxic symptoms of manganese exposure, even in areas of high traffic density, and no health risk from the use of MMT is likely. PMID:3438743

  8. Kramers non-magnetic superconductivity in LnNiAsO superconductors.

    PubMed

    Li, Yuke; Luo, Yongkang; Li, Lin; Chen, Bin; Xu, Xiaofeng; Dai, Jianhui; Yang, Xiaojun; Zhang, Li; Cao, Guanghan; Xu, Zhu-an

    2014-10-22

    We investigated a series of nickel-based oxyarsenides LnNiAsO (Ln=La, Ce, Pr, Nd, Sm) compounds. CeNiAsO undergoes two successive anti-ferromagnetic transitions at TN1=9.3 K and TN2=7.3 K; SmNiAsO becomes an anti-ferromagnet below TN?3.5 K; NdNiAsO keeps paramagnetic down to 2 K but orders anti-ferromagnetically below TN?1.3 K. Superconductivity was observed only in Kramers non-magnetic LaNiAsO and PrNiAsO with Tc=2.7 K and 0.93 K, respectively. The superconductivity of PrNiAsO is further studied by upper critical field and specific heat measurements, which reveal that PrNiAsO is a weakly coupled Kramers non-magnetic superconductor. Our work confirms that the nickel-based oxyarsenide superconductors are substantially different in mechanism to iron-based ones, and are likely to be described by the conventional superconductivity theory. PMID:25248377

  9. Quantifying absolute spin polarization with non-magnetic contacts in FM/ n-GaAs heterostructures

    NASA Astrophysics Data System (ADS)

    Geppert, Chad; Wienkes, Lee; Christie, Kevin; Patel, Sahil; Palmstrøm, Chris; Crowell, Paul

    2014-03-01

    We report on a novel method of quantifying spin accumulation in Co2MnSi/ n-GaAs and Fe/ n-GaAs heterostructures using a non-magnetic probe. The presence of a non-equilibrium spin polarization generates a large electrostatic potential shift relative to the equilibrium state. This is due to the combination of (1) the parabolic (non-constant) density of states and (2) the population imbalance between the two spin sub-bands. We observe this shift as a Hanle effect in a non-local, non-magnetic semiconducting contact. Since this signal depends only on experimentally accessible parameters of the bulk semiconductor, its magnitude may be used to quantify the injected spin polarization in absolute terms. By comparison with the (smaller) spin-valve signal observed with a second ferromagnetic contact, we demonstrate that this electrostatic shift scales quadratically with spin polarization, dephases in the presence of both applied and hyperfine fields, and is observable to higher temperatures than traditional non-local measurements. Quantitative modeling allows extraction of absolute polarizations in excess of 50 % at low temperatures, and further indicates that this contribution constitutes a large fraction of the three-terminal signal observed in these devices. Supported by NSF DMR-1104951; by STARnet, a SRC program sponsored by MARCO and DARPA; and by the NSF MRSEC program.

  10. Tetragonal and Hexagonal Iron-Manganese Carbides

    Microsoft Academic Search

    M. J. Duggin

    1967-01-01

    DURING recent studies of the iron-manganese-carbon system, specimens, each weighing approximately 5 g, were carefully prepared according to predetermined compositions. The components were 500-mesh powders of 99.995 per cent pure iron and spectroscopically pure carbon and a 200-mesh powder of 99.995 per cent pure manganese. The component powders were intimately mixed by shaking, then each specimen was packed into a

  11. Laser beam welding of new ultra-high strength and supra-ductile steels

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin

    2015-03-01

    Ultra-high strength and supra-ductile are entering fields of new applications. Those materials are excellent candidates for modern light-weight construction and functional integration. As ultra-high strength steels the stainless martensitic grade 1.4034 and the bainitic steel UNS 53835 are investigated. For the supra-ductile steels stand two high austenitic steels with 18 and 28 % manganese. As there are no processing windows an approach from the metallurgical base on is required. Adjusting the weld microstructure the Q+P and the QT steels require weld heat treatment. The HSD steel is weldable without. Due to their applications the ultra-high strength steels are welded in as-rolled and strengthened condition. Also the reaction of the weld on hot stamping is reflected for the martensitic grades. The supra-ductile steels are welded as solution annealed and work hardened by 50%. The results show the general suitability for laser beam welding.

  12. Pathophysiology of manganese-associated neurotoxicity.

    PubMed

    Racette, Brad A; Aschner, Michael; Guilarte, Tomas R; Dydak, Ulrike; Criswell, Susan R; Zheng, Wei

    2012-08-01

    Manganese (Mn) is a well established neurotoxin associated with specific damage to the basal ganglia in humans. The phenotype associated with Mn neurotoxicity was first described in two workers with occupational exposure to Mn oxide (Couper, 1837). Although the description did not use modern clinical terminology, a parkinsonian illness characterized by slowness of movement (bradykinesia), masked facies, and gait impairment (postural instability) appears to have predominated. Nearly 100 years later an outbreak of an atypical parkinsonian illness in a Chilean Mn mine provided a phenotypic description of a fulminant neurologic disorder with parkinsonism, dystonia, and neuropsychiatric symptoms (Rodier, 1955). Exposures associated with this syndrome were massive and an order of magnitude greater than modern exposures (Rodier, 1955; Hobson et al., 2011). The clinical syndrome associated with Mn neurotoxicity has been called manganism. Modern exposures to Mn occur primarily through occupations in the steel industry and welding. These exposures are often chronic and varied, occurring over decades in the healthy workforce. Although the severe neurologic disorder described by Rodier and Couper are no longer seen, several reports have suggested a possible increased risk of neurotoxicity in these workers (Racette et al., 2005b; Bowler et al., 2007; Harris et al., 2011). Based upon limited prior imaging and pathologic investigations into the pathophysiology of neurotoxicity in Mn exposed workers (Huang et al., 2003), many investigators have concluded that the syndrome spares the dopamine system distinguishing manganism from Parkinson disease (PD), the most common cause of parkinsonism in the general population, and a disease with characteristic degenerative changes in the dopaminergic system (Jankovic, 2005). The purpose of this symposium was to highlight recent advances in the understanding of the pathophysiology of Mn associated neurotoxicity from Caenorhabditis elegans to humans. Dr. Aschner's presentation discussed mechanisms of dopaminergic neuronal toxicity in C. elegans and demonstrates a compelling potential role of Mn in dopaminergic degeneration. Dr. Guilarte's experimental, non-human primate model of Mn neurotoxicity suggests that Mn decreases dopamine release in the brain without loss of neuronal integrity markers, including dopamine. Dr. Racette's presentation demonstrates a unique pattern of dopaminergic dysfunction in active welders with chronic exposure to Mn containing welding fumes. Finally, Dr. Dydak presented novel magnetic resonance (MR) spectroscopy data in Mn exposed smelter workers and demonstrated abnormalities in the thalamus and frontal cortex for those workers. This symposium provided some converging evidence of the potential neurotoxic impact of Mn on the dopaminergic system and challenged existing paradigms on the pathophysiology of Mn in the central nervous system. PMID:22202748

  13. Methylcyclopentadienyl Manganese Tricarbonyl as an Antiknock: Composition and Fate of Manganese Exhaust Products

    Microsoft Academic Search

    G. L. Ter Haar; M. E. Grifffing; M. Brandt; D. G. Oberding; M. Kapron

    1975-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) has been marketed as a combustion improver for fuel oil and turbine fuel. Use concentrations for this purpose are about 0.025 g manganese\\/gal in fuel oil and 0.08 to 0.5 g\\/gal in turbine fuels. In addition, it has been used to a small extent in gasoline.

  14. Chronic manganese poisoning: a neuropathological study with determination of manganese distribution in the brain.

    PubMed

    Yamada, M; Ohno, S; Okayasu, I; Okeda, R; Hatakeyama, S; Watanabe, H; Ushio, K; Tsukagoshi, H

    1986-01-01

    An autopsy case of a 52-year-old man suffering from chronic manganese poisoning (CMP) is reported with determination of the manganese distribution in the brain. The patient had been working in a manganese ore crushing plant since 1965. In 1967 he began to complain of difficulties in walking and diminished libido. Later, he developed various neuropsychiatric symptoms including euphoria, emotional incontinence, masked face, monotonous speech, "cock-walk", increased muscle tone, weakness of upper and lower extremities, tremor of the eye lids, and exaggeration of knee jerks. The major neuropathological change was degeneration of the basal ganglia, in which the pallidum was severely affected. The pallidum disclosed a loss and degeneration of nerve cells, which was especially marked in the medial segment, a prominent decrease of myelinated fibers, and moderate astrocytic proliferation. The substantia nigra was intact. Distribution of manganese in the brain of the present case of CMP was determined using flameless atomic absorption spectrometry and compared with control cases and also a case of Parkinson's disease (PD). There was no significant difference between the control cases and the case of PD in average concentration of manganese and its distribution in the brain. The present case of CMP showed no elevation in average concentration of manganese in the brain. However, there were some changes in its distribution. Thus, the continuance of neurological disorders in CMP is not linked to an elevated manganese concentration itself in the brain. CMP appears to be different from PD in neuropathology and manganese behavior in brain. PMID:3766127

  15. Interactions of the Airless Non-magnetized Moons with the Environment

    NASA Astrophysics Data System (ADS)

    Barabash, S. V.

    2014-12-01

    Airless non-magnetized moons absorb plasma impinging the surface. The absorption forms a plasma void which size and morphology are controlled by the ambient magnetic field and plasma parameters. We consider and compare the following cases: the large and small scale objects interaction with a supersonic plasma flow (Moon - solar wind, Phobos - solar wind), the large scale object interaction with a subsonic magntospheric plasma of the gas giants (Callisto - magnetosphere, Rhea - magnetosphere). Although for understanding the main features of the global interaction picture the assumption on the full absorption is sufficient, in reality the plasma - surface interaction is by far more complex. The plasma particles are backscattered, result in sputtering, and surface weathering. We also briefly review these processes to demonstrate the complexity of this, seemingly simple, class of the interactions with the environment.

  16. Electron localization and magnetism in SrRuO3 with non-magnetic cation substitution.

    PubMed

    Tong, W; Huang, F-Q; Chen, I-W

    2011-03-01

    The destruction of the ferromagnetism of alloyed SrRuO(3) can be caused by electron localization at the substitution sites. Among all the non-magnetic cations that enter the B site, Zr(4+) is the least disruptive to conductivity and ferromagnetism. This is because Zr(4+) does not cause any charge disorder, and its empty d electron states which are poorly matched in energy with the Ru t(2g)(4) states cause the least resonance scattering of Ru's d electrons. Conducting Sr(Ru, Zr)O(3) may be used as an electrode for perovskite-based thin film devices, while its insulating counterpart provides unprecedented magnetoresistance, seldom seen in other non-manganite and non-cobaltite perovskites. PMID:21411908

  17. Faraday Effect in Magnetic and Non-Magnetic Colloidal Nanoparticles in Water

    NASA Astrophysics Data System (ADS)

    Farah, Constantine; Zorba, Serkan; Maxwell, Thomas; Yin, Yadong; He, L.; Ye, M.

    2009-11-01

    We have investigated Faraday Effect in a variety of nanoparticle solutions. Verdet constant of superparamagnetic nanocrystal clusters of magnetite (Fe3O4), diluted in water, is measured as a function of particle size. Particle sizes ranging from 3 to 210 nm, resulted in a nonlinear size dependence in Verdet constant. The relationship between Verdet constant and particle size is possibly due to variation in magnetic domain sizes within the particles. Domain size evolution investigations are underway using X-ray diffraction. Non-magnetic nanoparticle solutions investigated consisted of silver, silver oxide, magnesium oxide, nickel oxide, and carbon nanotubes. Solutions demonstrated diamagnetic and paramagnetic properties, as expected. We believe that Faraday Effect is an efficient method of investigating magnetic properties of nanoparticles.

  18. Manganese Based Oxidative Technologies For Water/Wastewater Treatment

    E-print Network

    Desai, Ishan

    2013-08-27

    by facilitating redox reactions. The reactivity of manganese oxides with some emerging contaminants like 4-tert octylphenol (OP) in aqueous systems is yet to be explored. Additionally, manganese's use within treatment systems designed to remove trace organics...

  19. Cardiovascular Toxicities Upon Manganese Exposure

    PubMed Central

    Jiang, Yueming; Zheng, Wei

    2014-01-01

    Manganese (Mn)-induced Parkinsonism has been well documented; however, little attention has been devoted to Mn-induced cardiovascular dysfunction. This review summarizes literature data from both animal and human studies on Mn’s effect on cardiovascular function. Clinical and epidemiological evidence suggests that the incidence of abnormal electrocardiogram (ECG) is significantly higher in Mn-exposed workers than that in the control subjects. The main types of abnormal ECG include sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinister megacardia, and ST-T changes. The accelerated heartbeat and shortened P-R interval appear to be more prominent in female exposed workers than in their male counterparts. Mn-exposed workers display a mean diastolic blood pressure that is significantly lower than that of the control subjects, especially in the young and female exposed workers. Animal studies indicate that Mn is capable of quickly accumulating in heart tissue, resulting in acute or sub-acute cardiovascular disorders, such as acute cardiodepression and hypotension. These toxic outcomes appear to be associated with Mn-induced mitochondrial damage and interaction with the calcium channel in the cardiovascular system. PMID:16382172

  20. Development of an accelerator based system for in vivo neutron activation analysis measurements of manganese in humans

    NASA Astrophysics Data System (ADS)

    Arnold, Michelle Lynn

    2001-11-01

    Manganese is required by the human body, but as with many heavy elements, in large amounts it can be toxic, producing a neurological disorder similar to that of Parkinson's Disease. The primary industrial uses of the element are for the manufacturing of steel and alkali batteries. Environmental exposure may occur via drinking water or exhaust emissions from vehicles using gasoline with the manganese containing compound MMT as an antiknock agent (MMT has been approved for use in both Canada and the United States). Preclinical symptoms of toxicity have recently been detected in individuals occupationally exposed to airborne manganese at levels below the present threshold limit value set by the EPA. Evidence also suggests that early detection of manganese toxicity is crucial since once the symptoms have developed past a certain point, the syndrome will continue to progress even if manganese exposure ceases. The development of a system for in vivo neutron activation analysis (IVNAA) measurement of manganese levels was investigated, with the goal being to have a means of monitoring both over exposed and manganese deficient populations. The McMaster KN-accelerator was used to provide low-energy neutrons, activation within an irradiation site occurred via the 55Mn(n,gamma) 56Mn capture reaction, and the 847 keV gamma-rays emitted when 56Mn decayed were measured using one or more Nal(TI) detectors. The present data regarding manganese metabolism and storage within the body are limited, and it is unclear what the optimal measurement site would be to provide a suitable biomarker of past exposure. Therefore the feasibility of IVNAA measurements in three sites was examined---the liver, brain and hand bones. Calibration curves were derived, minimum detectable limits determined and resulting doses calculated for each site (experimentally in the case of the liver and hand bones, and through computer simulations for the brain). Detailed analytical calculations of the 7Li(p,n) 7Be reaction, used to produce neutrons by the KN, were conducted to determine neutron spectral information, angular distributions and yields. These data were used as input for the transport code MCNP, and computer simulations of experimental conditions were performed. The simulations consistently overestimate experiment measurements by a constant factor, and possible reasons for this discrepancy are discussed. It has been concluded that IVNAA measurements of the brain would only provide limited information, however, measurement of both the liver and hand bone should be possible. It is recommended that preliminary in vivo measurements be pursued for the hand, as metabolic data suggest that bone may be a long term storage site for manganese.

  1. Pulmonary clearance of manganese phosphate, manganese sulfate, and manganese tetraoxide by CD rats following intratracheal instillation.

    PubMed

    Vitarella, D; Moss, O; Dorman, D C

    2000-10-01

    Manganese (Mn) is ubiquitous in ambient air due to both industrial and crustal sources. It is also a component of the octane-enhancing fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT). The combustion of MMT by the automobile engine results in the formation of Mn particulates including phosphate, sulfate, and oxide forms. The objectives of this study were to determine the contribution of particle dissolution on pulmonary clearance rates of Mn sulfate (MnSO(4)), Mn phosphate, and Mn tetraoxide (Mn(3)O(4)) in CD rats following an intratracheal instillation exposure. In addition, brain (striatal) Mn concentrations were evaluated following exposure. Adult CD rats were intratracheally instilled with 0, 0.04, 0.08, or 0.16 microg Mn/g of either MnSO(4), Mn phosphate, or Mn(3)O(4). Rats were euthanized at 0, 1, 3, or 14 days after instillation. Lung and striatal Mn concentrations were measured by neutron activation analysis. Pulmonary clearance following single intratracheal instillation of MnSO(4), Mn phosphate, or Mn(3)O(4) was similar for each of the three compounds at each of the three doses used. All pulmonary clearance half-times were less than 0.5 day. At the concentrations used, striatal Mn levels were unaffected, and lung pathology was unremarkable. The dissolution rate constant of the Mn particles was determined in vitro using lung simulant fluids. The solubility of the Mn compounds was in general 20 to 40 times greater in Hatch artificial lung lining fluid than in Gamble lung simulant fluid. The dissolution rate constant of the water-soluble MnSO(4) particles in Hatch artificial lung fluid containing protein was 7.5 x 10(-4) g (Mn)/cm(2)/day, which was 54 times that of relatively water-insoluble Mn phosphate and 3600 times that of Mn(3)O(4). The dissolution rate constants for these compounds were sevenfold slower in Gamble lung fluid simulant. For both solutions, the time for half the material to go into solution differed only by factors of 1/83 to 1/17 to 1 for MnSO(4), Mn phosphate, and Mn(3)O(4), respectively, consistent with measured differences in size distribution, specific surface, and dissolution rate constant. These data suggest that dissolution mechanisms only played a role in the pulmonary clearance of MnSO(4), while nonabsorptive (e.g., mechanical transport) mechanisms predominate for the less soluble phosphate and oxide forms of Mn. PMID:10989370

  2. Environmental effects and exposures to manganese from use of methylcyclopentadienyl manganese tricarbonyl (MMT) in gasoline.

    PubMed

    Lynam, D R; Roos, J W; Pfeifer, G D; Fort, B F; Pullin, T G

    1999-01-01

    Methylcyclopentadienyl Manganese Tricarbonyl (MMT) has been used since the 1970s in the U.S. as a gasoline octane enhancer Extensive testing of the effects of MMT on regulated gaseous emissions carried out on a wide variety of automobiles showed that use of MMT resulted in significantly lower NOx emissions Tests showed that less than 15% of the manganese from MMT combustion was emitted from the tailpipe, mostly in the PM2.5 fraction as manganese phosphate, with some manganese sulfate and a very small amount of manganese oxide. MMT has been used in Canada in virtually all unleaded gasoline for about 20 years. A probability-based study involving over 900 personal exposure samples in Toronto confirmed exposures to airborne PM2.5 Mn in the general population are quite low (.008 microgram/m3-median). Ambient levels of airborne manganese in Toronto are about the same as those in areas where MMT is not used. Exposures to manganese among the general population in Toronto are well within safe limits determined by the U.S. EPA and other standard setting bodies around the world. PMID:10385878

  3. Manganese (II) induces chemical hypoxia by inhibiting HIF-prolyl hydroxylase: Implication in manganese-induced pulmonary inflammation

    SciTech Connect

    Han, Jeongoh [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of); Lee, Jong-Suk [Laboratory of Physiology, College of Pharmacy, Yeungnam University, Gyeongsan (Korea, Republic of); Choi, Daekyu; Lee, Youna; Hong, Sungchae; Choi, Jungyun; Han, Songyi [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of); Ko, Yujin; Kim, Jung-Ae [Laboratory of Physiology, College of Pharmacy, Yeungnam University, Gyeongsan (Korea, Republic of); Mi Kim, Young [Medicinal Chemistry, College of Pharmacy, Pusan National University, Busan (Korea, Republic of); Jung, Yunjin [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of)], E-mail: jungy@pusan.ac.kr

    2009-03-15

    Manganese (II), a transition metal, causes pulmonary inflammation upon environmental or occupational inhalation in excess. We investigated a potential molecular mechanism underlying manganese-induced pulmonary inflammation. Manganese (II) delayed HIF-1{alpha} protein disappearance, which occurred by inhibiting HIF-prolyl hydroxylase (HPH), the key enzyme for HIF-1{alpha} hydroxylation and subsequent von Hippel-Lindau(VHL)-dependent HIF-1{alpha} degradation. HPH inhibition by manganese (II) was neutralized significantly by elevated dose of iron. Consistent with this, the induction of cellular HIF-1{alpha} protein by manganese (II) was abolished by pretreatment with iron. Manganese (II) induced the HIF-1 target gene involved in pulmonary inflammation, vascular endothelial growth factor (VEGF), in lung carcinoma cell lines. The induction of VEGF was dependent on HIF-1. Manganese-induced VEGF promoted tube formation of HUVEC. Taken together, these data suggest that HIF-1 may be a potential mediator of manganese-induced pulmonary inflammation.

  4. Manganese oxide reduction as a form of anaerobic respiration

    Microsoft Academic Search

    Henry L. Ehrlich

    1987-01-01

    Some instances of bacterial manganese oxide reduction observed in nature and under laboratory conditions are a form of respiration. Anaerobiosis is not a necessary condition for its occurrence, although anaerobic reduction of manganese oxide which is inhibited by air has been reported. It is the kind of manganese reducing microorganism involved which determines whether anaerobic conditions are required. In at

  5. Essentiality, Toxicity, and Uncertainty in the Risk Assessment of Manganese

    Microsoft Academic Search

    William K. Boyes

    2010-01-01

    Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quantitatively across dose levels and routes of exposure, to account for mass balance, and to incorporate this information into

  6. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Cobalt lithium manganese nickel oxide. 721.10201 Section 721...721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and...identified as cobalt lithium manganese nickel oxide (PMN P-04-269; CAS...

  7. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Cobalt lithium manganese nickel oxide. 721.10201 Section 721...721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and...identified as cobalt lithium manganese nickel oxide (PMN P-04-269; CAS...

  8. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Cobalt lithium manganese nickel oxide. 721.10201 Section 721...721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and...identified as cobalt lithium manganese nickel oxide (PMN P-04-269; CAS...

  9. Biological manganese removal from potable water using trickling filters

    Microsoft Academic Search

    A. G. Tekerlekopoulou; I. A. Vasiliadou; D. V. Vayenas

    2008-01-01

    Two pilot-scale trickling filters were constructed and tested for manganese removal from potable water, using different fractions of silicic gravel as support media (mono- and multilayer filter). Manganese oxidation in drinking water was found to be cause by both biological oxidation and heterogeneous catalytic paths. Mixed culture populations were used to inoculate the trickling filters and the feed manganese concentrations

  10. EFFECT OF NORMAL AND HIGH MANGANESE DIETS ON THE ROLE OF BILE IN MANGANESE METABOLISM OF CALVES

    Microsoft Academic Search

    E. Abrams; J. W. Lassiter; W. J. Miller; M. W. Neathery; R. P. Gentry; D. M. Blackmon

    2010-01-01

    SUMMARY The role of bile in manganese metabolism and homeostasis was studied in Holstein bull calves fed diets containing 32 ppm manganese (normal) (control) or 1,000 ppm supplemental manganese (high-manganese) for 2 weeks before and 1 week after intravenous (IV) and duodenal S4Mn dosing. After dosing, all the bile was collected at 15 and 60 minutes, hourly to 12 hr

  11. Comparative toxicokinetics of manganese chloride and methylcyclopentadienyl manganese tricarbonyl (MMT) in Sprague-Dawley rats.

    PubMed

    Zheng, W; Kim, H; Zhao, Q

    2000-04-01

    The toxicokinetics of manganese (Mn) was investigated in male and female rats either following a single intravenous (iv) or oral dose of MnCl2 (6.0 mg Mn/kg), or following a single oral dose of methylcyclopentadienyl manganese tricarbonyl (MMT) (20 mg MMT/kg or 5.6 mg Mn/kg). The plasma concentrations of manganese were quantified by atomic absorption spectrophotometry (AAS). Upon iv administration of MnCl2, manganese rapidly disappeared from blood with a terminal elimination t1/2 of 1.83 h and CL8 of 0.43 L/h/kg. The plasma concentration-time profiles of manganese could be described by C = 41.9e(-424t) + 2.1e(-0.44t). Following oral administration of MnCl2, manganese rapidly entered the systemic circulation (Tmax = 0.25 h). The absolute oral bioavailability was about 13%. Oral dose of MMT resulted in a delayed Tmax(7.6 h), elevated Cmax (0.93 microg/ml), and prolonged terminal t1/2 (55.1 h). The rats receiving MMT had an apparent clearance (CL/F = 0.09 L/h x kg) about 37-fold less than did those who were dosed with MnCl2. Accordingly, the area under the plasma concentration-time curves (AUC) of manganese in MMT-treated rats was about 37-fold greater than that in MnCl2-treated rats. A gender-dependent difference in toxicokinetic profiles of plasma manganese was also observed. Female rats displayed a greater AUC than that of male rats. Although the apparent volume of distribution of manganese was similar in both sexes, the apparent clearance in males was about twice that observed in females. The results indicated that after oral administration, the MMT-derived manganese displayed higher and more prolonged plasma concentration-time profiles than MnCl2-derived manganese. Thus, MMT-derived manganese appeared likely to accumulate in the body following repeated exposure. PMID:10774811

  12. Manganese Distribution in the Brain and Neurobehavioral Changes Following Inhalation Exposure of Rats to Three Chemical Forms of Manganese

    Microsoft Academic Search

    Louise Normandin; Linda Ann Beaupré; Fariba Salehi; Annie St.-Pierre; Greg Kennedy; Donna Mergler; Roger F Butterworth; Suzanne Philippe; Joseph Zayed

    2004-01-01

    The central nervous system is an important target for manganese (Mn) intoxication in humans; it may cause neurological symptoms similar to Parkinson’s disease. Manganese compounds emitted from the tailpipe of vehicles using methylcyclopentadienyl manganese tricarbonyl (MMT) are primarily Mn phosphate, Mn sulfate, and Mn phosphate\\/sulfate mixture. The purpose of this study is to compare the patterns of Mn distribution in

  13. Long-Term Follow-Up of Workplace and Well Water Manganese Effects on Iron Status Indexes in Manganese Miners

    Microsoft Academic Search

    Massod Mashhadi; Akbar Boojar; Faranak Goodarzi; Mohamad Ali Basedaghat

    2002-01-01

    The authors assessed the effect of water reconstitution in the workplace by evaluating the iron status of manganese mine workers during a long-term study. Subsequent analyses and biological monitoring were performed in a group of 150 manganese miners before, and 2.8 yr after, reconstitution of drinking water in the miners' workplace. The authors found significantly high concentrations of manganese in

  14. Iron-manganese nanowires for magnetoresistance

    NASA Astrophysics Data System (ADS)

    Brown, Joshua M.; Wilson, Chester

    2010-04-01

    The research presented in this abstract pertains to nanowire-structured magnetic sensors fabricated by pulsed, template electrodeposition relying on giant magnetoresistance (GMR). System fabrication involves electrodepositing metals with a DC-biased square wave from a solution of iron-manganese solution into the porous aluminum oxide surface of an aluminum sheet. The chemical make-up of the resulting 20nm diameter, 500nm length nanowires was 6 at% manganese and 45 at% iron, which is desirable because the ferromagnetic layers (Fe) should be large in comparison with the nonmagnetic layers (Mn). The resulting nanowires exhibited a 73% drop in resistance when exposed to an external magnetic field.

  15. The formation of phosphate coatings on nitrided stainless steel

    Microsoft Academic Search

    J Flis; J Ma?kowski; T Zakroczymski; T Bell

    2001-01-01

    X10Cr18Ni9Ti stainless steel was plasma nitrided at 600°C or 575°C for 9 h and then subjected to the phosphating in zinc and manganese\\/iron phosphate baths. Depth profile analysis by glow discharge optical emission spectrometry (GDOES) showed that the coatings obtained in the Mn\\/Fe phosphate bath were about 10 ?m thick and were enriched in chromium. Surface analyses by GDOES and

  16. Wear resistance of steels for bimetallic farm machinery parts

    Microsoft Academic Search

    S. A. Golovanenko; A. N. Rozenbaum; S. I. Bulat; A. S. Tikhonov; V. S. Shumskii

    1969-01-01

    1.The wear resistance of steels for soil-cutting tools can be increased 30–50% by increasing the carbon content from 1.5 to 2%, the chromium content from 6 to 12%, and the addition of 1.5–2.0% Ti and V.2.It was found that carbon reduces the technological ductility the most (at 2.50% C the limit heating temperature is 1150°C).3.Vanadium, titanium, manganese, and silicon within

  17. Solidification mode and residual ferrite in low-Ni austenitic stainless steels

    Microsoft Academic Search

    A. Di Schino; M. G. Mecozzi; M. Barteri; J. M. Kenny

    2000-01-01

    The solidification modes of two new classes of austenitic stainless steels with a low content of Ni are shown. Their chemical composition is similar to that of the standard AISI 304 and AISI 316, except for the content of nickel, manganese and nitrogen. It is found that standard formulas for predicting the residual ferrite can be fairly well used in

  18. The Manganese Site of the Photosynthetic Water-Splitting Enzyme

    NASA Astrophysics Data System (ADS)

    George, Graham N.; Prince, Roger C.; Cramer, Stephen P.

    1989-02-01

    As the originator of the oxygen in our atmosphere, the photosynthetic water-splitting enzyme of chloroplasts is vital for aerobic life on the earth. It has a manganese cluster at its active site, but it is poorly understood at the molecular level. Polarized synchrotron radiation was used to examine the x-ray absorption of manganese in oriented chloroplasts. The manganese site, in the ``resting'' (S1) state, is an asymmetric cluster, which probably contains four manganese atoms, with interatomic separations of 2.7 and 3.3 angstroms; the vector formed by the 3.3-angstrom manganese pair is oriented perpendicular to the membrane plane. Comparisons with model compounds suggest that the cluster contains bridging oxide or hydroxide ligands connecting the manganese atoms, perhaps with carboxylate bridges connecting the 3.3-angstrom manganese pair.

  19. Analysis of manganese particulates from automotive decomposition of methylcyclopentadienyl manganese tricarbonyl

    Microsoft Academic Search

    C. Colmenares; Steven Deutsch; Cheryl Evans; A. J. Nelson; Louis J. Terminello; John G. Reynolds; Joseph W. Roos; Isaac L. Smith

    1999-01-01

    Particulates have been collected and analyzed from automotive vehicles operating on fuel containing the organometallic antiknock additive methylcyclopentadienyl manganese tricarbonyl. Electron spectroscopy for chemical analysis and L-edge X-ray absorption spectroscopy were used to study and identify the manganese species present in these emitted particulates. Results show that respirable size particulates with a mass median aerodynamic diameter of 2.5 ?m or

  20. Comparative Toxicokinetics of Manganese Chloride and Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in Sprague-Dawley Rats

    Microsoft Academic Search

    Wei Zheng; Hyaehwan Kim; Qiuqu Zhao

    2000-01-01

    The toxicokinetics of manganese (Mn) was investigated in male and female rats either following a single intravenous (iv) or oral dose of MnCl2 (6.0 mg Mn\\/kg), or following a single oral dose of methylcyclopentadienyl manganese tricarbonyl (MMT) (20 mg MMT\\/kg or 5.6 mg Mn\\/kg). The plasma concentrations of man- ganese were quantified by atomic absorption spectrophotometry (AAS). Upon iv administration

  1. Thermodynamic modelling of the formation of zinc-manganese ferrite spinel in electric arc furnace dust.

    PubMed

    Pickles, C A

    2010-07-15

    Electric arc furnace dust is generated when automobile scrap, containing galvanized steel, is remelted in an electric arc furnace. This dust is considered as a hazardous waste in most countries. Zinc is a major component of the dust and can be of significant commercial value. Typically, the majority of the zinc exists as zinc oxide (ZnO) and as a zinc-manganese ferrite spinel ((Zn(x)Mn(y)Fe(1-x-y))Fe(2)O(4)). The recovery of the zinc from the dust in metal recycling and recovery processes, particularly in the hydrometallurgical extraction processes, is often hindered by the presence of the mixed ferrite spinel. However, there is a paucity of information available in the literature on the formation of this spinel. Therefore, in the present research, the equilibrium module of HSC Chemistry 6.1 was utilized to investigate the thermodynamics of the formation of the spinel and the effect of variables on the amount and the composition of the mixed ferrite spinel. It is proposed that the mixed ferrite spinel forms due to the reaction of iron-manganese particulates with both gaseous oxygen and zinc, at the high temperatures in the freeboard of the furnace above the steel melt. Based on the thermodynamic predictions, methods are proposed for minimizing the formation of the mixed ferrite spinel. PMID:20356673

  2. Health and environmental testing of manganese exhaust products from use of methylcyclopentadienyl manganese tricarbonyl in gasoline.

    PubMed

    Pfeifer, G D; Roper, J M; Dorman, D; Lynam, D R

    2004-12-01

    This paper reviews recent research on the environmental effects of methylcyclopentadienyl manganese tricarbonyl (MMT), personal exposures to airborne Mn as a result of MMT use, chemical characterization of the manganese particulates emitted from the tailpipe and progress in developing a (PBPK) model for manganese in rodents. Recent studies show that manganese is emitted as a mixture of compounds with an average valence of about 2.2. The major products are sulfate, phosphate, and smaller amounts of oxides. Because only small amounts of Mn are used in gasoline (<18 mg Mn/gal) and less than 15% of the combusted Mn is emitted, soil along busy roads is not elevated in Mn, even after long-term use of MMT. A very large population-based study of manganese exposures in the general population in Toronto, where MMT has been used continuously for over 20 years, showed that manganese exposures were quite low, the median annual exposure was 0.008 microg Mn/m(3). A great amount of toxicological research on Mn has been carried out during the past few years that provides data for use in developing a PBPK model in rodents. These data add greatly to the existing body of knowledge regarding the relationship between Mn exposure and tissue disposition. When complete, the PBPK model will contribute to our better understanding of the essential neurotoxic dynamics of Mn. PMID:15504525

  3. Soil manganese enrichment from industrial inputs: a gastropod perspective.

    PubMed

    Bordean, Despina-Maria; Nica, Dragos V; Harmanescu, Monica; Banatean-Dunea, Ionut; Gergen, Iosif I

    2014-01-01

    Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems. PMID:24454856

  4. Metallurgy and Processing of Marine Manganese Nodules

    Microsoft Academic Search

    D. W. FUERSTENAU; K. N. HAN

    1983-01-01

    This paper reviews the state of the art in processing and extraction of ocean floor manganese nodules. It briefly reviews the mining sites where the abundant rich nodules occur and also discusses the metal distribution in nodules in view of economical processing and extraction of these metal values.The paper discloses in a detailed manner the physical and chemical characteristics of

  5. Lithium Manganese Silicate Positive Electrode Material

    NASA Astrophysics Data System (ADS)

    Yang, Qiong

    As the fast development of the electronic portable devices and drastic fading of fossil energy sources. The need for portable secondary energy sources is increasingly urgent. As a result, lithium ion batteries are being investigated intensely to meet the performance requirements. Among various electrode materials, the most expensive and capacity limiting component is the positive materials. Based on this, researches have been mostly focused on the development of novel cathode materials with high capacity and energy density and the lithium transition metal orthosilicates have been identified as possible high performance cathodes. Here in, we report the synthesis of a kind of lithium transition metal orthosilicates electrode lithium manganese silicate. Lithium manganese silicate has the advantage of high theoretical capacity, low cost raw material and safety. In this thesis, lithium manganese silicate are prepared using different silicon sources. The structure of silicon sources preferred are examined. Nonionic block copolymers surfactant, P123, is tried as carbon source and mophology directing agent. Lithium manganese silicate's performances are improved by adding P123.

  6. Environmental fate of methylcyclopentadienyl manganese tricarbonyl

    Microsoft Academic Search

    Arthur W. Garrison; N. L. Wolfe; R. R. Jr. Swank; M. G. Cipollone

    1995-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) has been proposed as an octane booster for unleaded gasoline; such use could result in ecological and human exposure through surface water and groundwater ecosystems. To evaluate the environmental risks from MMT, its environmental fate constants and transformation pathways must be known. Constants for physical parameters that would likely influence MMT fate were collected from the

  7. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...No. 7785-0987-097) is a pale pink, granular, odorless powder. It is obtained by reacting manganese compounds with sulfuric...products as defined in § 170.3(n)(29) of this chapter; milk products as defined in § 170.3(n)(31) of this...

  8. 21 CFR 184.1449 - Manganese citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Reg. No. 1002-46-65) is a pale orange or pinkish white powder. It is obtained by precipitating manganese carbonate from...products as defined in § 170.3(n)(29) of this chapter; milk products as defined in § 170.3(n)(31) of this...

  9. 21 CFR 184.1452 - Manganese gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...CAS Reg. No. 648-0953-0998) is a slightly pink colored powder. It is obtained by reacting manganese carbonate with gluconic...products as defined in § 170.3(n)(29) of this chapter; milk products as defined in § 170.3(n)(31) of this...

  10. Chemically activated manganese dioxide for dry batteries

    NASA Astrophysics Data System (ADS)

    Askar, M.; Abbas, H.

    1994-10-01

    The present investigation has enabled us to convert inactive beta-manganese dioxide to high electrochemically active types by chemical processes. Natural and chemically prepared beta-manganese dioxides were roasted at 1050 C to form Mn3O4. This compound was subjected to activation treatment using hydrochloric and sulfuric acid under various reaction conditions. The manganese dioxide so obtained was examined by x-ray diffraction, thermogravimetric, differential thermal, and chemical analyses. The structure of the dioxide obtained was found to be greatly dependent on the origin of MnO2 and type of acid used. Treatment with hydrochloric acid yielded the so-called gamma-variety while sulfuric acid tended to produce gamma- or alpha-MnO2. In addition, waste manganese sulfate obtained as by-product from sulfuric acid digestion treatment was recycled and electrolytically oxidized to gamma-MnO2. The discharge performance of the above-mentioned MnO2 samples as battery cathodic active material was evaluated and compared with the ordinary battery grade.

  11. Magnetic and orbital excitations in manganese oxides

    Microsoft Academic Search

    W. Koshibae; S. Ishihara; Y. Kawamura; S. Okamoto; J. Inoue; S. Maekawa

    1997-01-01

    The magnetic and orbital structures in manganese oxides with perovskite structure are examined by using the exact diagonalization method on finite-size clusters. The orbital degeneracy in the eg states is taken into account based on the effective Hamiltonian derived in the insulating state with strong Coulomb interaction. It is shown that A-, C- and G-type antiferromagnetic ordering occur as a

  12. Room-temperature defect-engineered spin filter based on a non-magnetic semiconductor.

    PubMed

    Wang, X J; Buyanova, I A; Zhao, F; Lagarde, D; Balocchi, A; Marie, X; Tu, C W; Harmand, J C; Chen, W M

    2009-03-01

    Generating, manipulating and detecting electron spin polarization and coherence at room temperature is at the heart of future spintronics and spin-based quantum information technology. Spin filtering, which is a key issue for spintronic applications, has been demonstrated by using ferromagnetic metals, diluted magnetic semiconductors, quantum point contacts, quantum dots, carbon nanotubes, multiferroics and so on. This filtering effect was so far restricted to a limited efficiency and primarily at low temperatures or under a magnetic field. Here, we provide direct and unambiguous experimental proof that an electron-spin-polarized defect, such as a Ga(i) self-interstitial in dilute nitride GaNAs, can effectively deplete conduction electrons with an opposite spin orientation and can thus turn the non-magnetic semiconductor into an efficient spin filter operating at room temperature and zero magnetic field. This work shows the potential of such defect-engineered, switchable spin filters as an attractive alternative to generate, amplify and detect electron spin polarization at room temperature without a magnetic material or external magnetic fields. PMID:19219029

  13. Instability of a magnetoelastic layer resting on a non-magnetic substrate

    NASA Astrophysics Data System (ADS)

    Danas, K.; Triantafyllidis, N.

    2014-09-01

    Magnetorheological elastomers (MREs) are ferromagnetic particle impregnated rubbers whose mechanical properties are altered by the application of external magnetic fields. Due to their coupled magneto-mechanical response, MREs are finding an increasing number of engineering applications. One such application is in haptics, where the goal is to actively control surface roughness. One way to achieve this is by exploiting the unstable regime of MRE substrate/layer assemblies subjected to transverse magnetic fields. In this work, we study the response of such an assembly subjected to a transverse magnetic field and in-plane stress. The layer is made up of a transversely isotropic MRE material, whose energy density has been obtained experimentally, while the substrate is a non-magnetic isotropic pure polymer/gel. An analytical solution to this problem based on a general, finite strain, 2D continuum modeling for both the MRE layer and the substrate shows that for adequately soft substrates there is a finite-wavelength buckling mode under a transverse magnetic field. Moreover, the critical magnetic field can be substantially reduced in the presence of a compressive stress of the assembly, thus opening the possibility for haptic applications operating under low magnetic fields.

  14. Development of third generation advanced high strength steels

    NASA Astrophysics Data System (ADS)

    McGrath, Meghan Colleen

    Lightweight duplex steels with combinations of either bainite, acicular ferrite, and austenite or martensite and austenite were investigated as third generation advanced high strength steels targeted for automotive applications. Large additions of manganese (> 13 wt%) and carbon (<0.2wt%) were employed to stabilize the austenite phase. Silicon additions between 1 and 2 wt% were added to suppress cementite formation. Strength and ductility were increased while density was decreased with aluminum additions between 2.4 and 5.5 wt% to the steel. This research addressed the dependence of alloying on microstructures and mechanical behavior for high manganese and aluminum duplex steels that were cast and subsequently hot rolled. Duplex steels with different volume fractions of primary delta-ferrite were used to study the crystallography of austenite fanned during the peritectic reaction. Solute profiles across the peritectic interface showed aluminum segregated near the interface which promoted bainitic ferrite formation. Thermal treatments were used to manipulate the concentration and type of oxides and the ferrite plate density was found to correlate with inclusions of low misfit in steels with austenite grain size of 16.5 microm. A steel with bainite and acicular ferrite produced an ultimate tensile strength of 970 MPa and elongation of 40%. The mechanical prope1iies depended on the strengths and size of the microstructural constituents. Work hardening behavior was examined in a steel exhibiting multiple martensitic transformation induced plasticity (gamma-austenite?epsilon-smartensite?alpha-martensite). A strain hardening exponent as high as 1.4 was observed with ultimate tensile strength and elongation as high as 1,165 MPa and 34%.

  15. A simple route to synthesize manganese germanate nanorods

    SciTech Connect

    Pei, L.Z., E-mail: lzpei1977@163.com; Yang, Y.; Yuan, C.Z.; Duan Taike; Zhang Qianfeng

    2011-06-15

    Manganese germanate nanorods have been synthesized by a simple route using germanium dioxide and manganese acetate as the source materials. X-ray diffraction observation shows that the nanorods are composed of orthorhombic and monoclinic manganese germanate phases. Scanning electron microscopy and transmission electron microscopy observations display that the manganese germanate nanorods have flat tips with the length of longer than 10 micrometers and diameter of 60-350 nm, respectively. The role of the growth conditions on the formation of the manganese germanate nanorods shows that the proper selection and combination of the growth conditions are the key factor for controlling the formation of the manganese germanate nanorods. The photoluminescence spectrum of the manganese germanate nanorods exhibits four fluorescence emission peaks centered at 422 nm, 472 nm, 487 nm and 530 nm showing the application potential for the optical devices. - Research Highlights: {yields} Manganese germanate nanorods have been synthesized by simple hydrothermal process. {yields} The formation of manganese germanate nanorods can be controlled by growth conditions. {yields} Manganese germanate nanorods exhibit good PL emission ability for optical device.

  16. Glutamate\\/Aspartate Transporter (GLAST), Taurine Transporter and Metallothionein mRNA Levels are Differentially Altered in Astrocytes Exposed to Manganese Chloride, Manganese Phosphate or Manganese Sulfate

    Microsoft Academic Search

    Keith M. Erikson; Robert L. Suber; Michael Aschner

    2002-01-01

    Manganese (Mn)-induced neurotoxicity can occur due to environmental exposure (air pollution, soil, water) and\\/or metabolic aberrations (decreased biliary excretion). High brain manganese levels lead to oxidative stress, as well as alterations in neurotransmitter metabolism with concurrent neurobehavioral deficits. Based on the few existing studies that have examined brain regional Mn concentration, it is likely that in pathological conditions, Mn concentration

  17. Hospitals In 'Magnet' Program Show Better Patient Outcomes On Mortality Measures Compared To Non-'Magnet' Hospitals.

    PubMed

    Friese, Christopher R; Xia, Rong; Ghaferi, Amir; Birkmeyer, John D; Banerjee, Mousumi

    2015-06-01

    Hospital executives pursue external recognition to improve market share and demonstrate institutional commitment to quality of care. The Magnet Recognition Program of the American Nurses Credentialing Center identifies hospitals that epitomize nursing excellence, but it is not clear that receiving Magnet recognition improves patient outcomes. Using Medicare data on patients hospitalized for coronary artery bypass graft surgery, colectomy, or lower extremity bypass in 1998-2010, we compared rates of risk-adjusted thirty-day mortality and failure to rescue (death after a postoperative complication) between Magnet and non-Magnet hospitals matched on hospital characteristics. Surgical patients treated in Magnet hospitals, compared to those treated in non-Magnet hospitals, were 7.7 percent less likely to die within thirty days and 8.6 percent less likely to die after a postoperative complication. Across the thirteen-year study period, patient outcomes were significantly better in Magnet hospitals than in non-Magnet hospitals. However, outcomes did not improve for hospitals after they received Magnet recognition, which suggests that the Magnet program recognizes existing excellence and does not lead to additional improvements in surgical outcomes. PMID:26056204

  18. The 3rd Generation Automobile Sheet Steels Presenting with Ultrahigh Strength and High Ductility

    Microsoft Academic Search

    Wenquan Cao; Jie Shi; Chang Wang; Cunyu Wang; Le Xu; Maoqiu Wang; Yuqing Weng; Han Dong

    \\u000a In this study, research and development on the 3rd generation automobile steel, with targets of R\\u000a m × A no less than 30 GPa% at R\\u000a m level of 1–1.5 GPa, was carried out to fabricate high strength and high ductility steel by two methodologies, one is the\\u000a medium manganese steels fabricated by intercritical annealing through austenite reverted transformation (ART-annealing) and\\u000a another is the

  19. Impact of speciation on removal of manganese and organic matter by nanofiltration 

    E-print Network

    De Munari, Annalisa; Schäfer, Andrea

    2010-01-01

    The removal of manganese and humic acid (HA) by two nanofiltration membranes, TFC-SR2 and TFC-SR3, was investigated in order to highlight the influence of speciation on manganese and HA retention. Manganese speciation ...

  20. 78 FR 54269 - Electrolytic Manganese Dioxide From Australia and China; Institution of Five-Year Reviews

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-03

    ...Electrolytic Manganese Dioxide From Australia and China; Institution of Five-Year...on electrolytic manganese dioxide from Australia and China would be likely to lead to...of electrolytic manganese dioxide from Australia and China (73 FR 58537-58539)....

  1. A FEASIBILITY STUDY OF RECYCLING OF MANGANESE FURNACE DUST

    Microsoft Academic Search

    R. Shen; G. Zhang; M. Dell' Amico; P. Brown; O. Ostrovski

    This paper presents results of a feasibility study of recycling manganese furnace dust generated in production of ferromanganese and silicomanganese at Tasmanian Electrometallurgical Company, Australia. Dried man- ganese furnace dust contains about 20 wt% of carbon, in average 33.4 wt% of manganese and 1.3 wt% of zinc. Manganese in the dust is in the form of MnO, Mn 3 O

  2. Manganese toxicity to chlorophyll synthesis in tobacco callus. [Nicotiana tabacum

    SciTech Connect

    Clairmont, K.B.; Hagar, W.G.; Davis, E.A.

    1986-01-01

    Tobacco (Nicotiana tabacum) pith explants were grown on manganese containing medium. At moderate concentration (10 millimolar), manganese selectivity inhibited chlorophyll synthesis, resulting initially in growth of white callus. Several weeks later the white callus turned brown due to the accumulation of a pigment identified as protoporphyrin IX by its elution profile using high performance liquid chromatography, by its absorption spectrum, and by its fluorescence properties. At a concentration of 100 millimolar manganese the pigment accumulated without growth of the explant.

  3. Maternal Blood Manganese Levels and Infant Birth Weight

    PubMed Central

    Zota, Ami R.; Ettinger, Adrienne S.; Bouchard, Maryse; Amarasiriwardena, Chitra J.; Schwartz, Joel; Hu, Howard; Wright, Robert O.

    2011-01-01

    Background Manganese is both an essential element and a known neurotoxicant to children. High manganese exposures have been associated with negative reproductive outcomes in animals, but few epidemiologic studies have examined the effects of human fetal manganese exposure. Methods We studied the association between maternal and umbilical cord blood manganese levels and birth weight in a cohort of 470 mother-infant pairs born at term (?37 weeks gestation) in Ottawa County, Oklahoma. Nonlinear spline and quadratic regression models were used to test the hypothesis of an inverted U-shaped relationship between manganese levels and birth weight. Results Mean (standard deviation) concentration of manganese was 2.4 (0.95) ?g/dL in the maternal blood and 4.2 (1.6) ?g/dL in the cord blood. Umbilical cord manganese was not associated with birth weight. A nonlinear relationship was observed between maternal manganese and birth weight after adjusting for potential confounders. Birth weight increased with manganese levels up to 3.1 ?g/L, and then a slight reduction in weight was observed at higher levels. Compared with the 3.1-?g/L point of inflection, birth weight estimates at the 5th (1.3 ?g/L) and 95th (4.0 ?g/L) percentiles of exposure were ?160 g (95% confidence interval = ?286 to ?33) and ?46 g (?38 to 131), respectively. Conclusions Maternal blood manganese levels during pregnancy are associated with birth weight in a nonlinear pattern in full-term infants. These findings suggest that manganese may affect fetal growth. Possible detrimental effects of elevated manganese levels on the fetus should be further examined in more highly exposed populations. PMID:19289966

  4. Manganese enhanced MRI (MEMRI): neurophysiological applications

    PubMed Central

    Inoue, Taeko; Majid, Tabassum; Pautler, Robia G.

    2012-01-01

    Manganese ion (Mn2+) is a calcium (Ca2+) analog that can enter neurons and other excitable cells through voltage gated Ca2+ channels. Mn2+ is also a paramagnetic that shortens the spin-lattice relaxation time constant (T1) of tissues where it has accumulated, resulting in positive contrast enhancement. Mn2+ was first investigated as a magnetic resonance imaging (MRI) contrast agent approximately 20 years ago to assess the toxicity of the metal in rats. In the late 1990s, Alan Koretsky and colleagues pioneered the use of manganese enhanced MRI (MEMRI) towards studying brain activity, tract tracing and enhancing anatomical detail. This review will describe the methodologies and applications of MEMRI in the following areas: monitoring brain activity in animal models, in vivo neuronal tract tracing and using MEMRI to assess in vivo axonal transport rates. PMID:22098448

  5. Arsenic removal by manganese greensand filters

    SciTech Connect

    Phommavong, T. [Saskatchewan Environment, Regina (Canada); Viraraghavan, T. [Univ. of Regina, Saskatchewan (Canada). Faculty of Engineering

    1994-12-31

    Some of the small communities in Saskatchewan are expected to have difficulty complying with the new maximum acceptable concentration (MAC) of 25 {micro}g/L for arsenic. A test column was set up in the laboratory to study the removal of arsenic from the potable water using oxidation with KMnO{sub 4}, followed by manganese greensand filtration. Tests were run using water from the tap having a background arsenic concentration of <0.5 {micro}g/L and iron concentration in the range of 0.02 to 0.77 mg/L. The test water was spiked with arsenic and iron. Results showed that 61 % to 98% of arsenic can be removed from the potable water by oxidation with KMnO{sub 4} followed by manganese greensand filtration.

  6. Sol-gel synthesis of manganese oxides

    NASA Astrophysics Data System (ADS)

    Bach, S.; Henry, M.; Baffier, N.; Livage, J.

    1990-10-01

    Transparent and stable manganese dioxide gels are obtained upon reduction of permanganate aqueous solutions AMnO 4 [ A = Li, Na, K, NH 4, N(CH 3) 4] by fumaric acid. All xerogels are amorphous when dried at room temperature. Their thermal behavior however depends on the nature of the counter cation A+. Ammonium permanganates lead to the formation of ?- or ?-Mn 2O 3 while AMnO 2 mixed oxides are obtained at high temperature when A = Li, Na, K. Other crystalline phases such as LiMn 2O 4 or Na 0.7MnO 2 are also formed at lower temperature around 500°C. Oxidation of these mixed oxides into sulfuric acid lead to the formation of ?- or ?-MnO 2 while A+ and Mn 2+ ions are released into the solution. Such manganese dioxides could be good candidates for making reversible cathodes in nonaqueous lithium batteries.

  7. Manganese Affects Streptococcus mutans Virulence Gene Expression

    Microsoft Academic Search

    P. Arirachakaran; E. Benjavongkulchai; S. Luengpailin; J. A. Banas

    2007-01-01

    Background\\/Aims: Studies of trace metals in drinking water and tooth enamel have suggested a caries-promoting potential for manganese (Mn). Additionally, Mn has been shown to be essential for the expression of mutans streptococci virulence factors such as the glucan-binding lectin (GBL) of Streptococcus sobrinus. The Streptococcus mutans glucan-binding protein (Gbp) GbpC is the functional analogue of the S. sobrinus GBL.

  8. Ferromagnetic Resonance in Manganese Ferrite Single Crystals

    Microsoft Academic Search

    P. E. Tannenwald

    1955-01-01

    The microwave properties of two types of manganese ferrite single crystals have been investigated by means of the ferromagnetic resonance phenomenon from 300°K to 4.2°K and at 24 000, 9100, 5600, and 2800 Mc\\/sec. The low resistivity of one of the crystals, believed to be related to the presence of divalent iron, led to significantly different microwave behavior. Resonance lines

  9. Microbial formation of manganese oxides. [Chlamydomonas sp

    SciTech Connect

    Greene, A.C.; Madgwick, J.C. (Univ. of New South Wales, Kensington (Australia))

    1991-04-01

    Microbial manganese oxidation was demonstrated at high Mn{sup 2+} concentrations (5 g/liter) in bacterial cultures in the presence of a microalga. The structure of the oxide produced varied depending on the bacterial strain and mode of culture. A nonaxenic, acid-tolerant microalga, a Chlamydomonas sp., was found to mediate formation of manganite ({gamma}-MnOOH). Bacteria isolated from associations with crude cultures of this alga grown in aerated bioreactors formed disordered {gamma}-MnO{sub 2} from Mn{sup 2+} at concentrations of 5 g/liter over 1 month, yielding 3.3 of a semipure oxide per liter. All algal-bacterial cultures removed Mn{sup 2+} from solution, but only those with the highest removal rates formed an insoluble oxide. While the alga was an essential component of the reaction, a Pseudomonas sp. was found to be primarily responsible for the formation of a manganese precipitate. Medium components - algal biomass and urea - showed optima at 5.7 and 10 g/liters, respectively. The scaled-up culture (50 times) gave a yield of 22.3 g (53 mg/liter/day from a 15-liter culture) of semipure disordered {gamma}MnO{sub 2}, identified by X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy, and had a manganese oxide O/Mn ratio of 1.92. The Mn(IV) content in the oxide was low (30.5%) compared with that of mined or chemically formed {gamma}MnO{sub 2} (ca. 50%). The shortfall in the bacterial oxide manganese content was due to biological and inorganic contaminants.

  10. Colossal magnetoresistance in manganese oxide perovskites

    Microsoft Academic Search

    M. R. Ibarra; J. M. De Teresa

    1998-01-01

    The large magnetoresistance observed in the manganese-oxide-based perovskites is explained on the basis of a strong electron-phonon and ferromagnetic interactions which provide the mechanism for the existence of dynamic electronic phase segregation in the form of magnetic polarons. These entities are responsible for the magnetic and lattice effects observed in these compounds. In this experimental work we give evidence of

  11. Manganese in the U.S. gasoline supply.

    PubMed

    Frumkin, H; Solomon, G

    1997-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic manganese compound recently approved for use in the United States as a gasoline additive. MMT use is expected to increase. This Commentary analyzes the impact of MMT use on population exposure to manganese, the health effects associated with manganese exposure, and the possibility that MMT use will lead to toxicity in the population. Although MMT use would result in only a small increment in most people's manganese exposure, certain populations will be disproportionately exposed. Although manganese is an essential nutrient at low levels, high-level manganese exposure leads to a characteristic severe nervous system toxicity. Pulmonary toxicity also occurs at high levels of exposure, and developmental toxicity to fetuses is an important concern based on more limited data. Selected subpopulations may be especially susceptible to the toxic effects of manganese. The critical question is whether the additional population exposure to manganese that would result from widespread MMT use would lead to toxic effects. Currently available evidence does not permit firm conclusions. Common sense and prudence therefore dictate that MMT not be used until further data are available and its safety is confirmed. Several measures are recommended to address the impending use of MMT in the U.S. gasoline supply. PMID:8986262

  12. Deposition of manganese in a drinking water distribution system.

    PubMed Central

    Sly, L I; Hodgkinson, M C; Arunpairojana, V

    1990-01-01

    The deposition of manganese in a water distribution system with manganese-related "dirty water" problems was studied over a 1-year period. Four monitoring laboratories with Robbins biofilm sampling devices fitted to the water mains were used to correlate the relationship among manganese deposition, the level of manganese in the water, and the chlorination conditions. Manganese deposition occurred by both chemical and microbial processes. Chemical deposition occurred when Mn(II) not removed during water treatment penetrated the filters and entered the distribution system, where it was oxidized by chlorine and chlorine dioxide used for disinfection. Microbial deposition occurred in areas with insufficient chlorination to control the growth of manganese-depositing biofilm. At 0.05 mg of Mn(II) per liter, the chemical deposition rate was much greater than microbial deposition. Significant deposition occurred at 0.03 mg of manganese per liter, and dirty water complaints were not eliminated until manganese levels were continuously less than 0.02 mg/liter and chlorination levels were greater than 0.2 mg/liter. A guideline level of 0.01 mg of manganese per liter is recommended. Images PMID:2317040

  13. A biokinetic model for manganese for use in radiation protection

    SciTech Connect

    Leggett, Richard Wayne [ORNL

    2011-01-01

    The ICRP is updating its recommendations regarding occupational exposure to radionuclides including the biokinetic models used to derive dose coefficients and assess bioassay data for internally deposited radionuclides. This report reviews biokinetic data for manganese and proposes a biokinetic model for systemic manganese consistent with the current database. The model provides a more detailed and biologically realistic description of the movement of absorbed manganese in the body than the model currently recommended by the International Commission on Radiological Protection (ICRP). The proposed model and current ICRP model yield broadly similar estimates of dose per unit activity of inhaled or ingested radio-manganese but differ substantially with regard to interpretation of bioassay data.

  14. Bioaccumulation of Manganese and Its Toxicity in Feral Pigeons ( Columba livia) Exposed to Manganese Oxide Dust (Mn 3O 4)

    Microsoft Academic Search

    P. Sierra; S. Chakrabarti; R. Tounkara; S. Loranger; G. Kennedy; J. Zayed

    1998-01-01

    Manganese tetroxide (Mn3O4) is a product from the combustion of methylcyclopentadienyl manganese tricarbonyl. Exposure to high levels of manganese can lead to serious health effects especially to the central nervous and respiratory systems. Very few studies on the effects of long-term low level exposure to Mn3O4have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity

  15. Addition of Titanium Oxide Inclusions into Liquid Steel to Control Nonmetallic Inclusions

    NASA Astrophysics Data System (ADS)

    Kiviö, Miia; Holappa, Lauri

    2012-04-01

    Titanium oxide inclusions in steel are well known to inhibit grain growth and act as nucleation sites for acicular ferrite because of absorbing manganese from the surrounding steel resulting in a manganese depleted zone around the inclusion. In this article, the inclusions resulting from TiO2 additions to low-alloyed C-Mn-Cr steel were studied. Different types of TiO2 containing materials were added to liquid steel before or during casting to get small titanium-oxide-rich inclusions in steel. The main goals were to find out what happens to TiO2 in liquid steel after addition and during cooling and to study further what type of inclusions are formed in the steel as a result of the TiO2 addition. Based on the thermodynamic calculations and the results of scanning electron microscope (SEM)-energy dispersive spectroscope (EDS) and SEM-electron backscatter diffraction (EBSD) analysis, TiO2 is first reduced to Ti3O5 in liquid steel at high temperatures and then to Ti2O3 during cooling at around 1573 K (1300 °C). Both reactions liberate oxygen, which reacts with Ti, Mn, and Al forming complex Ti2O3-rich inclusions. The results also show that TiO2 additions result in more TiOx + MnO inclusions compared with experiments with Ti addition and that the absolute amount of manganese present in the inclusions is much higher in experiments with TiO2 addition than in experiments with Ti additions.

  16. Manganese exposures in Toronto during use of the gasoline additive, methylcyclopentadienyl manganese tricarbonyl

    Microsoft Academic Search

    KENNY S CRUMP

    2000-01-01

    A year-long population-weighted study of personal exposures to particulate matter (PM2.5) was conducted in Toronto while the manganese-containing additive, methylcyclopentadienyl manganese tricarbonyl (MMT), was present in gasoline at an average level of 11.9 mg Mn\\/l, which was higher than the maximum of 8.3 mg Mn\\/l allowed in the U.S. In this study, 925 three-day personal samples of PM2.5 (air concentration

  17. Application of Bayesian Neural Network for modeling and prediction of ferrite number in austenitic stainless steel welds

    E-print Network

    Cambridge, University of

    , the influence of variations in the individual elements such as carbon, manganese, silicon, chromium, nickel, nickel, molybdenum, nitrogen, titanium, and vanadium were found to influence the ferrite number more in calculating the chromium equivalent. 1. 0 Introduction The ferrite content in stainless steel welds play

  18. Manganese Catalyzed C-H Halogenation.

    PubMed

    Liu, Wei; Groves, John T

    2015-06-16

    The remarkable aliphatic C-H hydroxylations catalyzed by the heme-containing enzyme, cytochrome P450, have attracted sustained attention for more than four decades. The effectiveness of P450 enzymes as highly selective biocatalysts for a wide range of oxygenation reactions of complex substrates has driven chemists to develop synthetic metalloporphyrin model compounds that mimic P450 reactivity. Among various known metalloporphyrins, manganese derivatives have received considerable attention since they have been shown to be versatile and powerful mediators for alkane hydroxylation and olefin epoxidation. Mechanistic studies have shown that the key intermediates of the manganese porphyrin-catalyzed oxygenation reactions include oxo- and dioxomanganese(V) species that transfer an oxygen atom to the substrate through a hydrogen abstraction/oxygen recombination pathway known as the oxygen rebound mechanism. Application of manganese porphyrins has been largely restricted to catalysis of oxygenation reactions until recently, however, due to ultrafast oxygen transfer rates. In this Account, we discuss recently developed carbon-halogen bond formation, including fluorination reactions catalyzed by manganese porphyrins and related salen species. We found that biphasic sodium hypochlorite/manganese porphyrin systems can efficiently and selectively convert even unactivated aliphatic C-H bonds to C-Cl bonds. An understanding of this novel reactivity derived from results obtained for the oxidation of the mechanistically diagnostic substrate and radical clock, norcarane. Significantly, the oxygen rebound rate in Mn-mediated hydroxylation is highly correlated with the nature of the trans-axial ligands bound to the manganese center (L-Mn(V)?O). Based on the ability of fluoride ion to decelerate the oxygen rebound step, we envisaged that a relatively long-lived substrate radical could be trapped by a Mn-F fluorine source, effecting carbon-fluorine bond formation. Indeed, this idea led to the discovery of the first Mn-catalyzed direct aliphatic C-H fluorination reactions utilizing simple, nucleophilic fluoride salts. Mechanistic studies and DFT calculations have revealed a trans-difluoromanganese(IV) species as the key fluorine transfer intermediate. In addition to catalyzing normal (19)F-fluorination reactions, manganese salen complexes were found to enable the incorporation of radioactive (18)F fluorine via C-H activation. This advance represented the first direct Csp(3)-H bond (18)F labeling with no-carrier-added [(18)F]fluoride and facilitated the late-stage labeling of drug molecules for PET imaging. Given the high reactivity and enzymatic-like selectively of metalloporphyrins, we envision that this new Heteroatom-Rebound Catalysis (HRC) strategy will find widespread application in the C-H functionalization arena and serve as an effective tool for forming new carbon-heteroatom bonds at otherwise inaccessible sites in target molecules. PMID:26042637

  19. Instrumentation of the variable-angle magneto-optic ellipsometer and its application to M-O media and other non-magnetic films

    NASA Technical Reports Server (NTRS)

    Zhou, Andy F.; Erwin, J. Kevin; Mansuripur, M.

    1992-01-01

    A new and comprehensive dielectric tensor characterization instrument is presented for characterization of magneto-optical recording media and non-magnetic thin films. Random and systematic errors of the system are studied. A series of TbFe, TbFeCo, and Co/Pt samples with different composition and thicknesses are characterized for their optical and magneto-optical properties. The optical properties of several non-magnetic films are also measured.

  20. Manganese exposures in Toronto during use of the gasoline additive, methylcyclopentadienyl manganese tricarbonyl.

    PubMed

    Crump, K S

    2000-01-01

    A year-long population-weighted study of personal exposures to particulate matter (PM2.5) was conducted in Toronto while the manganese-containing additive, methylcyclopentadienyl manganese tricarbonyl (MMT), was present in gasoline at an average level of 11.9 mg Mn/l, which was higher than the maximum of 8.3 mg Mn/l allowed in the U.S. In this study, 925 three-day personal samples of PM2.5 (air concentration of aerosol with an aerodynamic diameter of less than 2.5 microm) were collected, along with a record of participants' occupations, personal habits, surroundings, and activities during sampling. Stationary samples of PM2.5 were collected indoors and outdoors at a subset of participants' homes over the same 3-day periods. Three-day samples of PM2.5 were also collected at fixed locations. Personal exposures to PM2.5 were highly influenced by exposure to tobacco smoke, and were poorly correlated with outdoor levels (Kendall's tau=0.13). The mean concentration of PM2.5 in homes (21 microg/m3) was significantly higher than the mean outdoor level (15 microg/m3). By contrast, the mean PM2.5 Mn concentration (air concentration of Mn in PM2.5) was higher outdoors (9.7 ng/m3) than indoors (5.5 ng/m3). Other than from tobacco smoke, there were no indications of significant indoor sources of PM2.5 Mn in homes. The most important predictor of exposure to PM2.5 was time spent in the subway, and a high level (428 ng/m3) of PM2.5 Mn was measured in the subway. The source of this Mn was hypothesized to be friction erosion of subway rails. Small, but statistically significant correlations were present between personal exposures to PM2.5 Mn and several traffic-related variables (time spent in transit, in a motor vehicle, near a roadway with traffic, and in a parking garage). However, in a stepwise regression that adjusted for weather and personal activities, time in a motor vehicle was the only traffic-related variable significantly associated with PM2.5 Mn, and it was only the 10th most important personal activity variable in the final model. Concentrations of PM2.5 Mn were higher at two fixed locations than outside of participants' homes, which were likely further from high traffic areas than the fixed sites. Likewise, outdoor and fixed site samples collected during periods that included weekend days contained lower air concentrations of Mn than samples collected during weekdays when traffic was heavier. On the other hand, the monthly average concentration of Mn in gasoline was negatively correlated with both outdoor and personal PM2.5 Mn, which suggests that traffic-related sources of Mn other than MMT may be present. After omitting participants with exposure to Mn from certain identifiable non-MMT sources (subway riders, metal workers and persons exposed to tobacco smoke), the average (median) personal exposure of the remaining 325 participants to PM2.5 Mn was reduced from 14 ng/m3 (8.5 ng/m3 ) to 8.3 ng/m3 (7.0 ng/m3). Potential sources of this residual Mn exposure include, in addition to MMT, naturally occurring Mn in the earth's crust, other occupational exposure, airborne release of Mn from industrial operations, and friction erosion of Mn from steel-containing products. Taken together, these facts (elimination of participants with Mn exposure from known non-MMT sources reduced average exposures by 40%, the existence of multiple non-MMT sources of the remaining Mn exposure, and the negative correlation between MMT usage and PM2.5 Mn) suggest that the preponderance of personal Mn exposure was from non-MMT sources. PMID:10910116

  1. Metallic solvent extraction of manganese and titanium from ferroalloys

    Microsoft Academic Search

    A. J. Godsell; D. J. Fray

    1990-01-01

    The selective removal of valuable elements from ferroalloys has been investigated. It has been found that liquid bismuth is a suitable solvent for leaching manganese from its ferroalloy. High recoveries and rapid reaction rates were obtained for low-carbon ferromanganese, but results for the high-carbon ferromanganese and silicomanganese were less favorable due to the lower activity of manganese in these alloys

  2. Pwave Pairing and Colossal Magnetoresistance in Manganese Oxides

    E-print Network

    ­ferromagnetic transition and metal­insulator transition simultaneously. These phenomena were explained by the doubleP­wave Pairing and Colossal Magnetoresistance in Manganese Oxides Yong­Jihn Kim y Department paid to the manganese oxides since the observa­ tion of colossal magnetoresistance (CMR). 1\\Gamma4

  3. NEUTRON SCATTERING AND CATION ROTATIONAL MOTION IN TETRAMETHYLAMMONIUM MANGANESE CHLORIDE

    E-print Network

    Paris-Sud XI, Université de

    473 NEUTRON SCATTERING AND CATION ROTATIONAL MOTION IN TETRAMETHYLAMMONIUM MANGANESE CHLORIDE B sample of tetramethylammonium manganese chloride has been measured for 0-500 cm-1energy transfers, both of tetramethylammonium ions. Apart from its peculiar magnetic properties, N(CH3)4MnCl3 is remarkable in the orientational

  4. Methylcyclopentadienyl manganese tricarbonyl (MMT), plant uptake and effects on metabolism

    Microsoft Academic Search

    Angela R Jones; C. Mel Lytle; Rebekka L Stone; Lee D Hansen; Bruce N Smith

    2000-01-01

    In the USA and Canada, methylcyclopentadienyl manganese (MMT) is currently added to gasoline to replace tetraethyl lead as an antiknock fuel additive. Manganese concentrations in roadside soil and plants are increasing and correlated with distance from the roadway, traffic volume, plant type, and microhabitat. Radish (Raphanus sativus L.) seedlings were treated for either five or thirty-five days with different levels

  5. Rapid Determination of Methylcyclopentadienyl Manganese Tricarbonyl in Gasoline by FAAS

    Microsoft Academic Search

    Bin Du; Qin Wei; Guiying Xu

    1999-01-01

    A new method using microemulsified samples is presented. The method is suitable for the determination of manganese, present as methylcyclopentadienyl manganese tricarbonyl, in gasoline in the range 0?75?g ml. The method has the advantage of simplicity, speed and the use of aqeous standards for calibration instead of organic standards. Coexistent elements do not disturb the determination. Results obtained by this

  6. Manganese binding and oxidation by spores of a marine bacillus.

    PubMed Central

    Rosson, R A; Nealson, K H

    1982-01-01

    Mature, dormant spores of a marine bacillus, SG-1, bound and oxidized (precipitated) manganese on their surfaces. The binding and oxidation occurred under dormant conditions, with mature spores suspended in natural seawater. These heat-stable spores were formed in the absence of added manganese in the growth medium. The rate and amount of manganese bound by SG-1 spores was a function of spore concentration. Temperatures greater than 45 degrees C, pH values below 6.5, or the addition of EDTA or the metabolic inhibitors sodium azide, potassium cyanide, and mercuric chloride inhibited manganese binding and oxidation. However, SG-1 spores bound and oxidized manganese after treatment with glutaraldehyde, formaldehyde, ethylene oxide gas, or UV light, all of which killed the spores. Manganese oxidation never occurred in the absence of manganese binding to spores. The data suggest that Mn2+ was complexed by a spore component, perhaps an exosporium or a spore coat protein: once bound, the manganese was rapidly oxidized. Images PMID:6212577

  7. Manganese induced immune suppression of the lobster, Nephrops norvegicus

    Microsoft Academic Search

    Bodil Hernroth; Susanne P. Baden; Kristina Holm; Tove André; Irene Söderhäll

    2004-01-01

    Manganese (Mn) is one of the most abundant elements on earth, particularly in the soft bottom sediments of the oceans. As a micronutrient Mn is essential in the metabolic processes of organisms. However, at high concentrations the metal becomes a neurotoxin with well-documented effects. As a consequence of euthrophication, manganese is released from bottom sediments of coastal areas and the

  8. Manganese-Cycling Microbial Communities Inside Deep-Sea Manganese Nodules.

    PubMed

    Blöthe, Marco; Wegorzewski, Anna; Müller, Cornelia; Simon, Frank; Kuhn, Thomas; Schippers, Axel

    2015-07-01

    Polymetallic nodules (manganese nodules) have been formed on deep sea sediments over millions of years and are currently explored for their economic potential, particularly for cobalt, nickel, copper, and manganese. Here we explored microbial communities inside nodules from the northeastern equatorial Pacific. The nodules have a large connected pore space with a huge inner surface of 120 m(2)/g as analyzed by computer tomography and BET measurements. X-ray photoelectron spectroscopy (XPS) and electron microprobe analysis revealed a complex chemical fine structure. This consisted of layers with highly variable Mn/Fe ratios (<1 to >500) and mainly of turbostratic phyllomanganates such as 7 and 10 Å vernadites alternating with layers of Fe-bearing vernadite (?-MnO2) epitaxially intergrown with amorphous feroxyhyte (?-FeOOH). Using molecular 16S rRNA gene techniques (clone libraries, pyrosequencing, and real-time PCR), we show that polymetallic nodules provide a suitable habitat for prokaryotes with an abundant and diverse prokaryotic community dominated by nodule-specific Mn(IV)-reducing and Mn(II)-oxidizing bacteria. These bacteria were not detected in the nodule-surrounding sediment. The high abundance and dominance of Mn-cycling bacteria in the manganese nodules argue for a biologically driven closed manganese cycle inside the nodules relevant for their formation and potential degradation. PMID:26020127

  9. PRELIMINARY ASSESSMENT OF ATMOSPHERIC METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL AND PARTICULATE MANGANESE IN SELECTED URBAN SITES

    Microsoft Academic Search

    Christiane Thibault; Greg Kennedy; Lise Gareau; Joseph Zayed

    2002-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT: C 9 H 7 MnO 3 ) is an organometallic additive that has been used since 1976 as an octane enhancer in Canadian unleaded gasoline. Very few studies have determined its atmospheric concentrations and only one study offers recent data on its ambient level. This preliminary study aims to assess atmospheric concentrations of MMT and respirable

  10. Modeling the environmental fate of manganese from methylcyclopentadienyl manganese tricarbonyl in urban landscapes

    Microsoft Academic Search

    A. K. Bhuie; O. A. Ogunseitan; R. R. White; M. Sain; D. N. Roy

    2005-01-01

    The environmental impacts of gasoline additives such as lead (Pb) and Methyl Tertiary Butyl Ether (MTBE) are well documented, leading to the phasing out of these additives. In contrast, little is known about the health and environmental impacts of potential replacement chemicals such as Methylcyclopentadienyl Manganese Tricarbonyl (MMT). The combustion of MMT in gasoline leads to the formation of MnPO4

  11. Assessment of the permissible exposure level to manganese in workers exposed to manganese dioxide dust

    Microsoft Academic Search

    H A Roels; P Ghyselen; J P Buchet; E Ceulemans; R R Lauwerys

    1992-01-01

    The prevalence of neuropsychological and respiratory symptoms, lung ventilatory parameters, neurofunctional performances (visual reaction time, eye-hand coordination, hand steadiness, audioverbal short term memory), and several biological parameters (calcium, iron, luteinising hormone (LH), follicle stimulating hormone (FSH), and prolactin concentrations in serum, blood counts, manganese (Mn) concentration in blood and in urine) were examined in a group of workers (n =

  12. Investigation of non-magnetic alloys for the suppression of tritium permeation. Final report

    SciTech Connect

    Turnbull, John C.; Kessler, S. William; Eastman, G. Yale

    1980-07-01

    This report describes a small (300 man hour) literature survey relating to the suppression of tritium loss by permeation through the walls of fusion reactors. The program was based on prior in-house Thermacore work to suppress hydrogen permeation into high temperature (800/sup 0/C) heat pipes. The Thermacore approach involves selection of a steel with a small (.5 to 5%) aluminum content. The aluminum is diffused to the surface and oxidized. The present work was aimed at identification of alloys which might combine low tritium permeation with other properties desired in fusion reactor vessels, heat exchangers, lithium-handling plumbing and other components likely to contain tritium. These properties include low radiation damage, low magnetic permeability, high temperature strength, and compatibility with potential heat transfer and blanket materials. The work consisted of two tasks: Problem Definition and Literature Search and Analysis.

  13. Experimental Analysis and Modelling of Fe-Mn-Al-C Duplex Steel Mechanical Behaviour

    SciTech Connect

    Shiekhelsouk, M. N.; Favier, V.; Cherkaoui, M. [LPMM, ENSAM Metz, 4 rue Augustin Fresnel, Technopole, 57078 Metz Cedex 3 (France); Inal, K. [MECASURF, ENSAM Aix, 2 cours des Arts et Metiers, 13617 Aix en Provence (France); Bouaziz, O. [ARCELOR RESEARCH, Voie Romaine, BP 30320, F-57283 Maiziere les Metz Cedex (France)

    2007-04-07

    A new variety of duplex steels with high content of manganese and aluminum has been elaborated in Arcelor Research. These steels contain two phases: austenite and ferrite combining the best features of austenitic and ferritic steels. In this work, four duplex steels with different chemical composition and phase volume fraction are studied. The evolution of internal stresses for the two phases has been determined by X-ray diffraction during an in situ tensile test. These measurements results were used to determine the mechanical behaviour of the duplex steel using a micromechanical approach by scale transition for tensile tests. Though a good agreement between experiments and simulations is found at the macroscopic level, the calculated internal stresses of the austenitic phase do not match experimental results. These discrepancies are attributed to (i) a bad estimation of the austenite yield stress or (ii) the presence of kinematic hardening in the austenitic phase. A new step is then proposed to test these two hypotheses.

  14. Steel production

    SciTech Connect

    Sokolov, V.V.

    1995-01-01

    Twenty five years ago commercial steel production began at the West Siberian Metallurgical Combine in Russia in converter shop number one. A planned changeover to the continuous method of casting of all blooms and later, all slabs and plates will allow the combine to increase annual output by 20% without increasing steelmaking capacity. The gain will be made throughout the reduction in waste allowed by the new casting technology. Steel production at the combine now stands at eight million tons a year with converter shops number one and two presently rated as 3.5 and 4.3 million ton a year. Assuming a stable supply of charge materials and power, these levels of production should be attained after the introduction of the new casting and the ladle type steel finishing section that are being built. At the combine, a new ingot mold that increases the yield of sound metal that allows a fume-free lubrication of the molds, eliminating pollution from the lacquer based lubricants used previously.

  15. Spin dependent transport studies in magnetic, non-magnetic, antiferromagnetic, and half metals

    NASA Astrophysics Data System (ADS)

    Acharyya, Rakhi

    This thesis consists of three studies of Current-Perpendicular-to-the-Planes (CPP) Magnetoresistance (MR) of sputtered ferromagnetic/non-magnetic (F/N) multilayers. (a) The first study involves a double-blind comparison of our measurements of the interface specific resistance AR (area A through which the CPP current flows times the CPP resistance R) of Pd/Ir interfaces with no-free-parameter calculations. (b) The second study is of spin relaxation within the antiferromagnets (AF) IrMn and FeMn and at their interfaces with Cu. (c) The third study is of the MR of multilayers involving a nominal half-metal Heusler alloy, Co2Fe(Al0.5Si0.5) (CFAS). A true half-metal should give an especially large CPP-MR. This study involves a different sample geometry, combining optical lithography and ion-beam etching, with epitaxial sputtering at elevated temperatures. (a) For four pairs of lattice-matched metals (Ag/Au, Co/Cu, Fe/Cr, and Pt/Pd) having the same crystal structure and the same lattice parameter to within ˜1%, no-free-parameter calculations of 2AR, twice the interface specific resistance AR have agreed with measured values to within mutual uncertainties. For three pairs, the measured values were known when the calculations were made. For the fourth pair, Pt/Pd, they were not. In contrast, calculations for non-matched pairs, where the lattice parameters differed by 5% or more, disagreed with measured values. In this thesis we study a fifth pair, Pd and Ir, where the lattice parameter mismatch is intermediate, 1.3%. The project was done double-blind with theory collaborators Wang and Xia, with experiment and calculations shared only after both groups settled on their separate values. The values for Pd/Ir calculated with the same assumptions used previously were just outside of uncertainty of the measured ones. An improved calculation gave agreement between the two values. (b) Antiferromagnets (AFs) play important roles in CPP-MR devices as sources of pinning for F-layers in exchange-biased spin-valves (EBSVs), and are also part of a burgeoning field of AF spintronics. For both structures, it is important to understand spin-relaxation within sputtered AFs and at AF/N interfaces. A prior study of spin-relaxation in sputtered FeMn found strong spin-flipping at FeMn/Cu interfaces, but was unable to determine the size of spin-flipping within the FeMn itself. In this thesis we find strong spin-flipping at IrMn/Cu interfaces and confirm strong spin-flipping at FeMn/Cu interfaces. We also discovered an interesting new phenomenon, a weak magnetic dependence of AR in Py, that makes us unable to put a tight bound on the bulk spin-diffusion lengths in sputtered IrMn or FeMn. But these lengths are probably short. (c) The CPP-MR of an F/N multilayer will be enhanced by an F-metal with high spin scattering asymmetry, making such a multilayer more competitive for devices. Half-metallic ferromagnetic metals, such as Heusler alloys, are predicted to have high asymmetry. Experiments with the Heusler alloy CFAS have shown both large Tunneling Magnetoresistance (TMR) and large CPP-MR for multilayers with non-superconducting electrodes sputtered at room temperature and then post-annealed to 500°C. In this thesis we attempt to optimize epitaxial growth using high temperature sputtering to produce highly ordered Heusler alloys grown on superconducting electrodes. We are able to grow CFAS epitaxially, but have obtained maximum CPP MR only about one-third (40%) as large as we expected.

  16. [Ferrous-manganese oxidizing bacteria from the nature water].

    PubMed

    Qin, Song-yan; Ma, Fang; Huang, Peng

    2008-06-01

    Glass slides were hanged into a canal to acquire the ferrous-manganese oxidizing bacteria settled bio-film. Two isolated methods for ferrous-manganese oxidizing bacteria with special iron-manganese oxidizing matrix from the bio-film were tested. Element component of bacteria product and sheath structure of bacteria were analyzed. With two methods, plate cultivation and the novel semi-solid in situ cultivation method, strains belong to Family Leptothrix were isolated. XRF showed that the amorphous iron and manganese were two major metal elements of the precipitation formed by one strain of Leptothrix spp.. Through the microscope observation, one strain of Family Leptothrix was determined to form branch-like structured sheath, while another strain formed spider web-like structured sheath. Those isolated bacteria provide model strains for future testing of FISH probe and PCR primer of ferrous-manganese oxidizing bacteria. PMID:18763517

  17. Effect of quantity and route of administration of manganese monoxide on feed intake and serum manganese in ruminants

    SciTech Connect

    Black, J.R.; Ammerman, C.B.; Henry, P.R.

    1985-02-01

    The experiment investigated effects of high quantities of manganese and route of administration (diet versus capsule-dosed) on feed intake and blood characteristics in sheep. Twenty-four Florida native or Florida native by St. Croix crossbred wethers, 47 kg initially, were assigned randomly to eight treatments including basal diet supplemented with 0, 3000, 6000, or 9000 ppm manganese as a reagent grade manganese monoxide or basal diet plus gelatin capsules containing the equivalent of 0, 3000, 6000, or 9000 ppm manganese based on intake of the previous day. Three sheep per treatment were provided feed and tap water for ad libitum intake. Sheep were fed basal diet for 7 days followed by a 21-day experimental period, then placed back on the basal diet for 7 days. Average daily feed intake was reduced by increasing supplemental manganese, regardless of route. Animals dosed by capsule consumed less feed than those administered manganese in the diet. Serum manganese increased as manganese supplementation increased, but route of administration had no effect.

  18. Manganese Content of Tradescancia Species Exposed to Automotive Combustion of Methylcyclopentadienyl Manganese Tricarbonyl in Urban and Rural Landscapes

    Microsoft Academic Search

    Amrit K. Bhuie; Oladele A. Ogunseitan; D. N. Roy

    2004-01-01

    The purpose of this study is to assess the effect of manganese (Mn) from methylcyclopentadienyl manganese tricarbonyl (MMT) on grass (Tradescancia) species beside the major urban and rural highways in the greater Toronto area. Grass clippings were collected at distances up to 40 m from the roadside of a wooded, weakly exposed site (E) and two unwooded, highly exposed sites

  19. Effect of quantity and route of administration of manganese monoxide on feed intake and serum manganese in ruminants

    Microsoft Academic Search

    J. R. Black; C. B. Ammerman; P. R. Henry

    1985-01-01

    The experiment investigated effects of high quantities of manganese and route of administration (diet versus capsule-dosed) on feed intake and blood characteristics in sheep. Twenty-four Florida native or Florida native by St. Croix crossbred wethers, 47 kg initially, were assigned randomly to eight treatments including basal diet supplemented with 0, 3000, 6000, or 9000 ppm manganese as a reagent grade

  20. THE STATE OF MANGANESE IN THE PHOTOSYNTHETIC APPARATUS. II. X-RAY ABSORPTION EDGE STUDIES ON MANGANESE IN PHOTOSYNTHETIC MEMBRANES

    SciTech Connect

    Kirby, J.A.; Goodin, D.B.; Wydrzynski, T.; Robertson, A.S.; Klein, M.P.

    1980-11-01

    X-ray absorption spectra at the Manganese K-edge are presented for spinach chloroplasts, and chloroplasts which have been Tris-treated and hence unable to evolve oxygen. A significant change in the electronic environment of manganese is observed and is attributed to the release of manganese from the thylakoid membranes with a concomitant change in oxidation state. A correlation of the K-edge energy, defined as the energy at the first inflection point, with coordination charge has been established for a number of manganese compounds of known structure and oxidation state. Comparison of the manganese K-edge energies of the chloroplast samples with the reference compounds places the average oxidation state of the chloroplasts between +2 and +3. Using the edge spectra for Tris-treated membranes which were osmotically shocked to remove the released manganese, difference edge spectra were synthesized to approximate the active pool of manganese. Coordination charge predictions for this fraction are consistent with an average resting oxidation state higher than +2. The shape at the edge is also indicative of heterogeneity of the manganese site, of low symmetry, or both.

  1. Steel Recycling Institute (SRI)

    NSDL National Science Digital Library

    1998-01-01

    The Steel Recycling Institute (SRI) provides information and statistics on steel recycling; it was founded by a group of steel companies and the American Iron and Steel Institute (AISI). Originally a grassroots effort focused only on the recycling of steel cans, the SRI now promotes the recycling of all steel products. The SRI homepage provides online access to its three publications, The Dockside Recycler, The Recycling Magnet, and The Appliance Recycler. Recycling information is divided into four categories: cans, cars, appliances, and construction material. Users can use the recycling database to find the nearest steel recycling location. Links provides a large list of both commercial and non-commercial steel sites.

  2. Low cumulative manganese exposure affects striatal GABA but not dopamine.

    PubMed

    Gwiazda, R H; Lee, D; Sheridan, J; Smith, D R

    2002-05-01

    The introduction of the anti-knock methylcyclopentadienyl manganese (Mn) tricarbonyl (MMT) in gasoline has raised concerns about the potential for manganese neurotoxicity. Because subpopulations such as the elderly in the early stages of neurodegenerative disease may be at increased risk for manganese toxicity, a pre-Parkinsonism rat model was used to evaluate whether sub-chronic manganese exposure can aggravate the neurochemical and behavioral dysfunctions characteristic of Parkinsonism. Sub-threshold levels of dopamine depletion of 3.5, 53 and 68% were generated via intrastriatal unilateral 6-hydroxydopamine (6-OHDA) doses. A sub-chronic dosing regimen of low cumulative manganese exposure (4.8 mg Mn/kg body weight, 3 i.p. injections per week x 5 weeks) was started 4 weeks after 6-OHDA treatments. Neurochemical and neuromotor (functional observational battery (FOB)) measures were evaluated. Manganese produced significant (P < 0.05) reductions of 30-60% in motor function. This effect was exacerbated in the presence of a pre-Parkinsonism condition [Neurotox. Teratol. 22 (2000) 851]. Manganese did not affect striatal dopamine, but resulted in significant increases in striatal y-aminobutyric acid (GABA) of 16 and 22% (P < 0.01) in both striati and a borderline non-significant 4% increase in frontal cortex (P = 0.076). Manganese treatment produced increased aspartate (P < 0.01) in the manganese and 6-OHDA treated striatum. In light of previous studies predominantly showing dopamine depletion with elevated manganese exposures, the significant effects of manganese on striatal GABA but not on striatal dopamine at the low cumulative exposure administered here suggest a progression in manganese toxicity with increasing cumulative dose, whereby GABA levels are adversely affected before striatal dopamine levels. Because these neurochemical disruptions were accompanied by motor dysfunction that was exacerbated in the presence of a pre-Parkinsonism condition, an increased environmental burden of manganese may have deleterious effects on populations with sub-threshold neurodegeneration in the basal ganglia (e.g. pre-Parkinsonism). PMID:12164549

  3. Experimental study of magnetization AC loss in MgB2 wires and cables with non-magnetic sheath

    NASA Astrophysics Data System (ADS)

    Ková?, Ján; Šouc, Ján; Ková?, Pavol; Hušek, Imrich; Gömöry, Fedor

    2013-12-01

    The influence of MgB2 wires design on the magnetization AC loss was studied. AC loss in external AC magnetic field perpendicular to the wire axis was measured in the temperature range from 18 K up to 40 K and at the frequencies of 72 Hz and 144 Hz, respectively. For this purpose the experimental apparatus combining magnetization measurement system and non-magnetic vacuum vessel with two-stage crycooler for sample cooling has been used. To clarify the influence of wire architecture on the AC loss in non-magnetic GlidCop sheathed MgB2 composites experiments on a single-core, 30-filament un-twisted and also twisted samples were performed. MgB2 cables containing 7 mono-core strands and 30 filament strands were also measured. While in the cable containing single core strands the hysteresis loss was dominant, in the un-twisted wire and the cable with un-twisted filaments the coupling loss prevailed. The effect of decoupling was observed in all twisted filamentary wires. The obtained results show that in 7 strands cable the AC loss of strands is crucial to the overall AC loss of a cable.

  4. Simultaneous removal of cationic and anionic dyes by the mixed sorbent of magnetic and non-magnetic modified sugarcane bagasse.

    PubMed

    Yu, Jun-Xia; Zhu, Jing; Feng, Li-Yuan; Chi, Ru-An

    2015-08-01

    Magnetic carboxyl groups modified (MMS) and non-magnetic amine groups modified (AMS) sugarcane bagasse were prepared and mixed to remove cationic and anionic dye simultaneously from aqueous solution. For comparison, the adsorption performances of MMS, AMS and the mixed sorbent for basic magenta (cationic dye) and congo red (anionic dye) were investigated in the binary system. Zeta potential analysis showed that MMS was negatively charged and AMS was positively charged in the investigated pH range. The adsorption capacities of MMS for basic magenta and congo red were 1.24 and 0.04mmolg(-1), while those of AMS were 0.04 and 1.55mmolg(-1), respectively. Both of MMS and AMS had high adsorption capacity and affinity toward opposite-charged dye but low adsorption capacity and affinity toward similar-charged dye. Adsorption experiments in the binary system showed that only the mixed sorbent could remove the two dyes simultaneously from aqueous solution (removal efficiencies >90%). The amounts of basic magenta and congo red absorbed on the mixed sorbent both increased linearly with the increase of their initial concentrations in the investigated range. The dye loaded mixed magnetic and non-magnetic sorbents could be separated by a magnet. MMS and AMS could be regenerated by using acid and alkaline eluents, respectively. After regeneration, the MMS and AMS could be mixed again and used repeatedly. The mixed sorbent had great potential in practical dye waste water treatment. PMID:25897851

  5. Controlled release of manganese into water from coated experimental fertilizers: laboratory characterization.

    PubMed

    Novillo, J; Rico, M I; Alvarez, J M

    2001-03-01

    The release of manganese into water from controlled-release formulations containing manganese EDTA or manganese lignosulfonate was studied. These fertilizers were obtained in the laboratory by adhering the source of manganese over urea pellets and by adding a coating. The materials used as adhesives and coatings were mixtures of rosins plus tricalcium phosphate. With regard to the chemical composition, these formulations conformed to national and international standards for commercial fertilizers. The rate of release of manganese was a function of both the source of manganese used and the coating thickness. Under the same conditions the release of manganese was greater for formulations with manganese EDTA than with manganese lignosulfonate. To predict the kinetic behaviors of the two series of formulations, mathematical equations were established. The manganese source plus rosin coatings improved the handling and storage characteristics of the commercial urea pellets. The study of the rosin coatings using scanning electron microscopy showed that they were compact and homogeneous. PMID:11312854

  6. Environmental fate of methylcyclopentadienyl manganese tricarbonyl

    SciTech Connect

    Garrison, A.W.; Wolfe, N.L.; Swank, R.R. Jr. [Environmental Protection Agency, Athens, GA (United States). Environmental Research Lab.; Cipollone, M.G. [Technology Applications, Inc., Athens, GA (United States)

    1995-11-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) has been proposed as an octane booster for unleaded gasoline; such use could result in ecological and human exposure through surface water and groundwater ecosystems. To evaluate the environmental risks from MMT, its environmental fate constants and transformation pathways must be known. Constants for physical parameters that would likely influence MMT fate were collected from the literature or calculated; the compound`s octanol/water partition coefficient and water solubility were determined in the laboratory. Experiments were designed to screen MMT for transformation pathways that are significant over environmentally short time frames. The MMT was found to be fairly stable in the dark in aquifer materials and sediments at various Eh levels; half-lives ranged from 0.2 to 1.5 years in aquifer materials at 25 C. (These matrices were not optimized for biodegradation.) On the other hand, MMT photolyzes rapidly in distilled water; its half-life in midday sunlight in water is approximately 1 min and the disappearance quantum yield is 0.13. Photodegradation products were identified as cyclopentadiene, methyl cyclopentadiene, carbon monoxide, and a manganese carbonyl that readily oxidized to trimanganese tetroxide.

  7. THE MANGANESE MERCURY STAR ?1 BOOTIS

    PubMed Central

    Montgomery, John Wm.; Aller, Lawrence H.

    1969-01-01

    High-dispersion plates secured with the Coudé spectrograph of the Lick 120 inch telescope have been used to analyze the peculiar A star ?1 Bootis. Spectral-energy distribution measurements are combined with line-intensity data for iron and manganese in two stages of ionization to obtain a fit with model atmospheres for Teff = 13,000°K and log g = 4. The influence of adopted T and g on the derived abundances is discussed. Although C, O, Mg, Si, Ti, Cr, and Fe appear to have nearly normal (i.e., solar) abundances, strontium appears to be enhanced in abundance by an order of magnitude, and scandium is about 50 times overabundant, while manganese and yttrium appear to be two orders of magnitude overabundant. If the identification of gallium is correct, this element is overabundant by a factor approaching 100,000; while if ?3983.90 is to be attributed to HgII, as Bidelman suggests, the overabundance of this element is many orders of magnitude. PMID:16578698

  8. Sol-gel synthesis of manganese oxides

    SciTech Connect

    Bach, S.; Henry, M.; Baffier, N.; Livage, J. (Ecole Nationale Superieure de Chimie de Paris (France))

    1990-10-01

    Transparent and stable manganese dioxide gels are obtained upon reduction of permanganate aqueous solutions AMnO{sub 4} (A = Li, Na, K, NH{sub 4}, N(CH{sub 3}){sub 4}) by fumaric acid. All xerogels are amorphous when dried at room temperature. Their thermal behavior however depends on the nature of the counter cation A{sup +}. Ammonium permanganates lead to the formation of {alpha}- or {gamma}-Mn{sub 2}O{sub 3} while AMnO{sub 2} mixed oxides are obtained at high temperature when A = Li, Na, K. Other crystalline phases such as LiMn{sub 2}O{sub 4} or Na{sub 0.7}MnO{sub 2} are also formed at lower temperature around 500{degree}C. Oxidation of these mixed oxides into sulfuric acid lead to the formation of {lambda}- or {delta}-MnO{sub 2} while A{sup +} and Mn{sup 2+} ions are released into the solution. Such manganese dioxides could be good candidates for making reversible cathodes in nonaqueous lithium batteries.

  9. Clean cast steel technology. Final report

    SciTech Connect

    Bates, C.E.; Griffin, J.A.

    1998-06-01

    This report documents the results obtained from the Clean Cast Steel Technology Program financially supported by the DOE Metal Casting Competitiveness Research Program and industry. The primary objective of this program is to develop technology for delivering steel free of oxide macroinclusions to mold cavities. The overall objective is to improve the quality of cast steel by developing and demonstrating the technology for substantially reducing surface and sub-surface oxide inclusions. Two approaches are discussed here. A total of 23 castings were produced by submerge pouring along with sixty conventionally poured castings. The submerged poured castings contained, on average, 96% fewer observable surface inclusions (11.9 vs 0.4) compared to the conventionally poured cast parts. The variation in the population of surface inclusions also decreased by 88% from 5.5 to 0.7. The machinability of the casting was also improved by submerged pouring. The submerge poured castings required fewer cutting tool changes and less operator intervention during machining. Subsequent to these trials, the foundry has decided to purchase more shrouds for continued experimentation on other problem castings where submerge pouring is possible. An examination of melting and pouring practices in four foundries has been carried out. Three of the four foundries showed significant improvement in casting quality by manipulating the melting practice. These melting practice variables can be grouped into two separate categories. The first category is the pouring and filling practice. The second category concerns the concentration of oxidizable elements contained in the steel. Silicon, manganese, and aluminum concentrations were important factors in all four foundries. Clean heats can consistently be produced through improved melting practice and reducing exposure of the steel to atmospheric oxygen during pouring and filling.

  10. Characterization of Microbial Communities in Coal Mine Drainage Treatment Systems With Elevated Manganese

    Microsoft Academic Search

    H. Tan; G. Zhang; W. Burgos

    2007-01-01

    Sediment samples were collected from two coal mine drainage treatment sites in western Pennsylvania. Both of the sites use constructed limestone beds to passively treat acidic coal mine drainage containing elevated manganese (Mn). Site #1 has influent manganese of 150 mg\\/L and effluent manganese between 40-100 mg\\/L. Site #2 has influent manganese of 20 mg\\/L and effluent manganese of less

  11. Influence of particle solubility on the delivery of inhaled manganese to the rat brain: manganese sulfate and manganese tetroxide pharmacokinetics following repeated (14-day) exposure.

    PubMed

    Dorman, D C; Struve, M F; James, R A; Marshall, M W; Parkinson, C U; Wong, B A

    2001-01-15

    Dissolution rate can influence the pulmonary clearance of a metal and thus affect its delivery to the brain and other organs. The goal of this study was to determine the exposure-response relationship for the relatively soluble sulfate (MnSO(4)) and insoluble tetroxide (Mn(3)O(4)) forms of inhaled manganese in adult male CD rats. Rats were exposed 6 h/day for 7 days/week (14 exposures) to either MnSO(4) or Mn(3)O(4) at 0, 0.03, 0.3, or 3 mg Mn/m(3). End-of-exposure olfactory bulb, striatum, cerebellum, bile, lung, liver, femur, serum, and testes (n = 6 rats/concentration/chemical) manganese concentrations and whole-body (54)Mn elimination were then determined. Increased whole-body (54)Mn clearance rates were observed in animals from the high-dose (3 mg Mn/m(3)) MnSO(4) and Mn(3)O(4) exposure groups. Elevated manganese concentrations in the lung were observed following MnSO(4) and Mn(3)O(4) exposure to > or=0.3 mg Mn/m(3). Increased olfactory bulb and femur manganese concentrations were also observed following MnSO(4) exposure at > or=0.3 mg Mn/m(3). Elevated striatal, testes, liver, and bile manganese concentrations were observed following exposure to MnSO(4) at 3 mg Mn/m(3). Elevated olfactory bulb, striatal, femur, and bile manganese concentrations were observed following exposure to Mn(3)O(4) at 3 mg Mn/m(3). Animals exposed to MnSO(4) (3 mg Mn/m(3)) had lower lung and higher olfactory bulb and striatal manganese concentrations compared with levels achieved following similar Mn(3)O(4) exposures. Our results suggest that inhalation exposure to soluble forms of manganese results in higher brain manganese concentrations than those achieved following exposure to an insoluble form of manganese. PMID:11162771

  12. Effect of alloying and heat treatment on the structure and tribological properties of nitrogen-bearing stainless austenitic steels under abrasive and adhesive wear

    Microsoft Academic Search

    L. G. Korshunov; Yu. N. Goikhenberg; N. K. Chernenko

    2007-01-01

    The effect of nitrogen, silicon, and aging modes on the structure, resistance to abrasive and adhesive wear, friction factor,\\u000a and mechanical properties of nitrogen-bearing (0.27–0.83% N) chromium-manganese austenitic steels is studied. It is shown\\u000a that it is possible to ensure a favorable combination of mechanical and tribological properties in such steels by choosing\\u000a the appropriate chemical composition and aging mode.

  13. An atom-probe tomographic study of the temporal evolution of the nanostructure of Fe–Cu based high-strength low-carbon steels

    Microsoft Academic Search

    Dieter Isheim; R. Prakash Kolli; Morris E. Fine; David N. Seidman

    2006-01-01

    A three-dimensional (3D) knowledge of the atomic-scale structure is necessary for improving the design and understanding of modern materials with complex microstructures, such as high-performance steels. Local-electrode atom-probe tomography is used to obtain atom-by-atom 3D reconstructions to characterize three versions of a copper, nickel, manganese, and aluminum bearing high-strength low-carbon steel, which achieve their high tensile yield strength, up to

  14. Surface nanocrystallization of 310S stainless steel and its effect on oxidation behavior

    SciTech Connect

    Liu, Z.; He, Y.; Gao, W. [Univ. of Auckland (New Zealand). Dept. of Chemical and Materials Engineering] [Univ. of Auckland (New Zealand). Dept. of Chemical and Materials Engineering

    1998-02-01

    Two techniques, unbalanced magnetron sputter deposition and high-energy short-pulsed plasma discharge, have been used to produce a nanocrystalline surface on AISI 310S stainless steel specimens. The average grain size after surface modification was estimated as {approximately} 100 nm by using atomic force microscopy. Cyclic oxidation was performed at 1,000 C with treated and untreated 310S stainless steel specimens. The oxide products formed on the specimens consisted of an outer spinel layer that was rich in chromium, iron, manganese, and nickel, and an inner chromium-rich layer. It was found that the concentrations of iron and manganese in the outer layer of treated specimens were higher, and adherence of the scale was better in the treated specimens. The observed oxidation behavior can be explained by the increase of the creep diffusion rate in the fine oxide scale formed on the nanocrystalline surfaces.

  15. Surface nanocrystallization of 310s stainless steel and its effect on oxidation behavior

    NASA Astrophysics Data System (ADS)

    Liu, Z.; He, Y.; Gao, W.

    1998-02-01

    Two techniques, unbalanced magnetron sputter deposition and high-energy short-pulsed plasma discharge, have been used to produce a nanocrystalline surface on AISI310S stainless steel specimens. The average grain size after surface modification was estimated as ˜100 nm by using atomic force microscopy. Cyclic oxidation was performed at 1000 °C with treated and untreated 310S stainless steel specimens. The oxide products formed on the specimens consisted of an outer spinel layer that was rich in chromium, iron, manganese, and nickel, and an inner chromium-rich layer. It was found that the concentrations of iron and manganese in the outer layer of treated specimens were higher, and adherence of the scale was better in the treated specimens. The observed oxidation behavior can be explained by the increase of the creep diffusion rate in the fine oxide scale formed on the nanocrystalline surfaces.

  16. Manganese exposure among smelting workers: blood manganese-iron ratio as a novel tool for manganese exposure assessment.

    PubMed

    Cowan, Dallas M; Fan, Qiyuan; Zou, Yan; Shi, Xiujuan; Chen, Jian; Aschner, Michael; Rosenthal, Frank S; Zheng, Wei

    2009-02-01

    Unexposed control subjects (n = 106), power distributing and office workers (n = 122), and manganese (Mn)-exposed ferroalloy smelter workers (n = 95) were recruited to the control, low and high groups, respectively. Mn concentrations in saliva, plasma, erythrocytes, urine and hair were significantly higher in both exposure groups than in the controls. The Fe concentration in plasma and erythrocytes, however, was significantly lower in Mn-exposed workers than in controls. The airborne Mn levels were significantly associated with Mn/Fe ratio (MIR) of erythrocytes (eMIR) (r = 0.77, p < 0.01) and plasma (pMIR) (r = 0.70, p < 0.01). The results suggest that the MIR may serve as a useful biomarker to distinguish Mn-exposed workers from the unexposed, control population. PMID:19283519

  17. Manganese exposure among smelting workers: blood manganese–iron ratio as a novel tool for manganese exposure assessment

    PubMed Central

    Cowan, Dallas M.; Fan, Qiyuan; Zou, Yan; Shi, Xiujuan; Chen, Jian; Aschner, Michael; Rosenthal, Frank S.; Zheng, Wei

    2014-01-01

    Unexposed control subjects (n = 106), power distributing and office workers (n = 122), and manganese (Mn)-exposed ferroalloy smelter workers (n = 95) were recruited to the control, low and high groups, respectively. Mn concentrations in saliva, plasma, erythrocytes, urine and hair were significantly higher in both exposure groups than in the controls. The Fe concentration in plasma and erythrocytes, however, was significantly lower in Mn-exposed workers than in controls. The airborne Mn levels were significantly associated with Mn/Fe ratio (MIR) of erythrocytes (eMIR) (r = 0.77, p < 0.01) and plasma (pMIR) (r = 0.70, p < 0.01). The results suggest that the MIR may serve as a useful biomarker to distinguish Mn-exposed workers from the unexposed, control population. PMID:19283519

  18. Chronic oral administration of methylcyclopentadienyl manganese tricarbonyl altered brain biogenic amines in the mouse: comparison with inorganic manganese.

    PubMed

    Komura, J; Sakamoto, M

    1994-07-01

    This study was conducted to investigate the effects associated with high dose administration of organic manganese to mice and to compare these effects with those of inorganic manganese. The disposition and toxicity of methylcyclopentadienyl manganese tricarbonyl (MMT; a potential substitute for lead in gasoline) in the brains of ddY mice was studied after 12-months administration (at 0.5 g/kg of MMT) in food. Mice exposed to inorganic manganese received 2.0 g/kg of MnCl2 in food for the same period. There was no significant difference in food intake between the control mice and the MMT-exposed mice or MnCl2-exposed mice. Normetanephrine level in the cerebellum of the MMT-exposed group was significantly increased compared with the control, and correlated with the manganese concentration. The manganese concentration was significantly increased in the cerebellum of the MMT-exposed group compared with the control and MnCl2-exposed groups. On the whole, methoxylation from the 3-hydroxyl of catecholamine tended to be promoted by manganese. PMID:8042203

  19. Distributions of Manganese, Iron, and Manganese-Oxidizing Bacteria In Lake Superior Sediments of Different Organic Carbon Content

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Nealson, Kenneth H.

    1989-01-01

    Profiles of oxygen, soluble and particulate manganese and iron, organic carbon and nitrogen were examined in Lake Superior sediment cores, along with the distribution and abundance of heterotrophic and manganese oxidizing bacteria. Analyses were performed using cores collected with the submersible Johnson Sea Link II. Three cores, exhibiting a range of organic carbon content, were collected from the deepest basin in Lake Superior and the north and south ends of the Caribou trough, and brought to the surface for immediate analysis. Minielectrode profiles of oxygen concentration of the three cores were carried out using a commercially available minielectrode apparatus. Oxygen depletion to less than 1% occurred within 4 cm of the surface for two of the cores, but not until approximately 15 cm for the core from the south basin of the Caribou trough. The three cores exhibited very different profiles of soluble, as well as leachable, manganese and iron, suggesting different degrees of remobilization of these metals in the sediments. Vertical profiles of viable bacteria and Mn oxidizing bacteria, determined by plating and counting, showed that aerobic (and facultatively aerobic) heterotrophic bacteria were present at the highest concentrations near the surface and decreased steadily with depth, while Mn oxidizing bacteria were concentrations primarily at and above the oxic/anoxic interface. Soluble manganese in the pore waters, along with abundant organic carbon, appeared to enhance the presence of manganese oxidizing bacteria, even below the oxic/anoxic interface. Profiles of solid-phase leachable manganese suggested a microbial role in manganese reprecipitation in these sediments.

  20. Reduced Atmospheric Manganese in Montreal Following Removal of Methylcyclopentadienyl Manganese Tricarbonyl (MMT)

    Microsoft Academic Search

    Alexandre Joly; Jean Lambert; Claude Gagnon; Greg Kennedy; Donna Mergler; Ariane Adam-Poupart; Joseph Zayed

    2011-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) was used between 1990 and 2003 as an antiknock agent and as an octane booster\\u000a in Canadian unleaded gasoline. Its combustion leads to Mn emissions. The objective of this research was to examine the variations\\u000a in atmospheric Mn in Montreal (Canada) from 2001 to 2007, covering the period prior (2001–2003) to and following (2005–2007)\\u000a MMT use.

  1. Environmental contamination and human exposure to manganese – contribution of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline

    Microsoft Academic Search

    Joseph Zayed; Adolf Vyskocil; Greg Kennedy

    1999-01-01

    The organomanganese compound MMT (methylcyclopentadienyl manganese tricarbonyl), an antiknock additive in unleaded gasoline,\\u000a has been used in Canada since 1976. Indeed, Canada is the only country where MMT is almost exclusively used. In October 1995,\\u000a by court decision the Environmental protection Agency (EPA) granted Ethyl's waiver for the use of MMT in the United States.\\u000a Paradoxically, in 1997 the federal

  2. Airborne manganese particulates and methylcyclopentadienyl manganese tricarbonyl (MMT) at selected outdoor sites in Montreal.

    PubMed

    Zayed, J; Thibault, C; Gareau, L; Kennedy, G

    1999-01-01

    This study aims to assess the atmospheric concentrations of methylcyclopentadienyl manganese tricarbonyl (MMT), respirable manganese (MNR) and total manganese (MnT) in certain specific microenvironments and to provide an estimation of human exposure to MnR. Sampling was carried out in five microenvironments: a gas station, an underground car park, downtown Montreal, near an expressway and near an oil refinery. The samples were collected using Gil-Air portable pumps during three days and were analyzed by instrumental neutron activation analysis (INAA). The mean concentrations of MnR, MnT and MMT were 0.036 microgram m-3, 0.103 microgram m-3 and 0.005 microgram m-3 respectively. The MnR/MnT ratios vary from 25% to 43% (mean 35%) while the MMT/MnT ratios averaged about 5%. Furthermore, the mean concentration of the MnR measured near the expressway (0.053 microgram m-3) is similar to the United States Environmental Protection Agency (U.S. EPA) reference concentration (RfC = 0.05 microgram m-3). The average daily environmental exposure dose to MNR is estimated at 0.010 microgram kg-1 d-1 and its contribution to the multimedia exposure (air, food and water) is low. The overall results show a lack of potential exposure to MMT and substantial concentrations of MnR near an expressway. PMID:10385879

  3. Manganese: brain transport and emerging research needs.

    PubMed

    Aschner, M

    2000-06-01

    Idiopathic Parkinson's disease (IPD) represents a common neurodegenerative disorder. An estimated 2% of the U.S. population, age 65 and older, develops IPD. The number of IPD patients will certainly increase over the next several decades as the baby-boomers gradually step into this high-risk age group, concomitant with the increase in the average life expectancy. While many studies have suggested that industrial chemicals and pesticides may underlie IPD, its etiology remains elusive. Among the toxic metals, the relationship between manganese intoxication and IPD has long been recognized. The neurological signs of manganism have received close attention because they resemble several clinical disorders collectively described as extrapyramidal motor system dysfunction, and in particular, IPD and dystonia. However, distinct dissimilarities between IPD and manganism are well established, and it remains to be determined whether Mn plays an etiologic role in IPD. It is particularly noteworthy that as a result of a recent court decision, methylcyclopentadienyl Mn tricarbonyl (MMT) is presently available in the United States and Canada for use in fuel, replacing lead as an antiknock additive. The impact of potential long-term exposure to low levels of MMT combustion products that may be present in emissions from automobiles has yet to be fully evaluated. Nevertheless, it should be pointed out that recent studies with various environmental modeling approaches in the Montreal metropolitan (where MMT has been used for more than 10 years) suggest that airborne Mn levels were quite similar to those in areas where MMT was not used. These studies also show that Mn is emitted from the tail pipe of motor vehicles primarily as a mixture of manganese phosphate and manganese sulfate. This brief review characterizes the Mn speciation in the blood and the transport kinetics of Mn into the central nervous system, a critical step in the accumulation of Mn within the brain, outlines the potential susceptibility of selected populations (e.g., iron-deficient) to Mn exposure, and addresses future research needs for Mn. PMID:10852840

  4. Hydrothermal Manganese Mineralization Near the Samoan Hotspot

    NASA Astrophysics Data System (ADS)

    Hein, J. R.; Staudigel, H.; Koppers, A.; Hart, S. R.; Dunham, R.

    2006-12-01

    The thickest beds of hydrothermal manganese oxides recovered to date from the global ocean were collected from a volcanic cone in the south Pacific. In April 2005, samples were dredged aboard the R.V. Kilo Moana from a volcanic cone on the lower flank of Tulaga seamount (about 2,700 m water depth; 14° 39.222' S; 170° 1.730' W), located 115 km SW of Vailulu'u, the volcanically and hydrothermally active center of the Samoan hotspot. Additional hydrothermal manganese samples were collected off Ofu Island (dredge Alia 107), 72 km to the WSW of Vailulu'u. Manganese-oxide beds up to 9 cm thick are composed of birnessite and 10 Å manganates. Some layers consist of Mn-oxide columnar structures 4 cm long and 1 cm wide, which have not been described previously. The mean Mn and Fe contents of 18 samples are 51 weight percent and 0.76 weight percent, respectively. Elevated concentrations of Li (mean 0.11 wt. percent) are indicators of a hydrothermal origin, and distinguishes these samples, along with the high Mn and low Fe contents, from hydrogenetic Fe-Mn crusts. Other enriched elements include Ba (mean 0.14 percent), Cu (249 ppm), Mo (451 ppm), Ni (400 ppm), Zn (394 ppm), V (214 ppm), and W (132 ppm). Chondrite-normalized REE patterns show large negative Ce anomalies and LREE enrichments, both characteristic of hydrothermal Mn deposits. Small negative Eu anomalies are not typical of hydrothermal deposits and can be explained either by the absence of leaching of plagioclase by the hydrothermal fluids or by the precipitation of Eu-rich minerals, such as barite and anhydrite, at depth. The high base-metal contents indicate that sulfides are not forming deeper in the hydrothermal system or that such deposits are being leached by the ascending fluids. Textures of the thickest Mn deposits indicate that the Mn oxides formed below the seabed from ascending fluids during multiple phases of waxing and waning hydrothermal pulses. The deposits were later exposed at the seafloor by erosional or mass wasting events; subsequently a thin layer of hydrogenetic Fe-Mn oxides accreted on the exposed surface. Mn-oxide filled veins may represent part of a feeder system. The thick sediment-free Mn-oxide layers locally grade into Mn-oxide cemented volcaniclastic beds. Our results indicate the extensive production of hydrothermal Mn on a regional basis, probably from multiple hydrothermal sources within the Samoan chain, and from the Tonga arc/back-arc system immediately to the west, as determined in previous studies.

  5. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  6. Positron Annihilation Spectroscopy of Nanostructural Features in Model Reactor Pressure Vessel Steels

    SciTech Connect

    Glade, S C; Wirth, B D; Asoka-Kumar, P; Sterne, P A; Odette, G R

    2003-07-16

    Irradiation embrittlement in nuclear reactor pressure vessel steels results from the formation of a high number density of nanometer sized copper rich precipitates and sub-nanometer defect-solute clusters. We present positron annihilation spectroscopy (PAS) results to characterize the compositions and magnetic character of these defects in model A533B reactor pressure vessel steels. The results confirm the presence of copper-rich precipitates after irradiation. The measured orbital electron momentum spectra indicate the precipitates are alloyed with Mn and Ni. The copper precipitates larger than R {approx} 1.2 nm (from SANS measurements) are non-magnetic, which limits the possible Fe content of the precipitates to at most a few %. Notably, large vacancy clusters observed in neutron irradiated Fe-Cu alloys were not observed in the steels after irradiation.

  7. Electronic properties of manganese impurities in germanium

    NASA Astrophysics Data System (ADS)

    Lauwaert, J.; Segers, S. H.; Moens, F.; Opsomer, K.; Clauws, P.; Callens, F.; Simoen, E.; Vrielinck, H.

    2015-05-01

    The electronic properties of manganese in crystalline germanium have been investigated by means of deep level transient spectroscopy (DLTS). Mn was diffused in the material by a thermal treatment at 700 °C. Next to the deep levels of nickel and copper, which are known contaminants in Ge treated at high temperature, three not previously reported levels were observed. These two hole and one electron traps, with apparent energy level positions at EV +0.136 eV, EV +0.342 eV and EC ? 0.363 eV, were assigned to substitutional Mn. The analysis of the carrier capture cross-sections, the absence of field-assisted emission and the observation of the Mn2? electron paramagnetic resonance spectrum in n-type Ge:Mn at low temperature are all compatible with Mn introducing two acceptor and one donor levels in the band gap of Ge.

  8. Manganese induced parkinsonism: a case report.

    PubMed

    Kim, J W; Kim, Y; Cheong, H K; Ito, K

    1998-08-01

    Manganese (Mn) intoxication is known to induce parkinsonism. Mn-induced parkinsonism preferentially affect the globus pallidus in contrast to idiopathic parkinsonism where degeneration predominantly involves the nigral pars compacta. We describe a 51-year-old man who had been occupationally exposed to Mn. He had parkinsonian features including masked face, resting tremor, and bradykinesia. He also had a cock walk and a particular propensity to fall in a backward gait. There was no sustained therapeutic response to levodopa. A fluorodopa PET scan was normal. This case indicates that Mn-induced parkinsonism can be differentiated from idiopathic parkinsonism in that the former has unique clinical features and a normal fluorodopa PET scan. PMID:9741552

  9. Dermal administration of manganese porphyrin by iontophoresis.

    PubMed

    Ito, Fuminori; Imamura, Shinya; Asayama, Shoichiro; Kanamura, Kiyoshi; Kawakami, Hiroyoshi

    2014-08-01

    The present study describes a technique for dermal administration of cationic manganese porphyrin (Mn-porphyrin), an antioxidant with superoxide dismutase (SOD) activity, in hairless mouse. In general, the stratum corneum on the surface of the skin represents a barrier to passive diffusion of therapeutic agents by standard dermal administration. The present study investigated whether, dermal administration of Mn-porphyrin solution using iontophoresis, the electrical dermal administration technique, could overcome this barrier. We visually confirmed that Mn-porphyrin had penetrated to the reverse side of the hairless mouse skin after iontophoresis for a short period. With prolonged iontophoresis, the ratio of detectable Mn-porphyrin solution on the reverse side of the hairless mouse skin increased. In the future, this technique could provide an innovative approach for delivery of this antioxidant in intractable disease. PMID:24907770

  10. Role of astrocytes in manganese mediated neurotoxicity

    PubMed Central

    2013-01-01

    Astrocytes are responsible for numerous aspects of metabolic support, nutrition, control of the ion and neurotransmitter environment in central nervous system (CNS). Failure by astrocytes to support essential neuronal metabolic requirements plays a fundamental role in the pathogenesis of brain injury and the ensuing neuronal death. Astrocyte-neuron interactions play a central role in brain homeostasis, in particular via neurotransmitter recycling functions. Disruption of the glutamine (Gln)/glutamate (Glu) -?-aminobutyric acid (GABA) cycle (GGC) between astrocytes and neurons contributes to changes in Glu-ergic and/or GABA-ergic transmission, and is associated with several neuropathological conditions, including manganese (Mn) toxicity. In this review, we discuss recent advances in support of the important roles for astrocytes in normal as well as neuropathological conditions primarily those caused by exposure to Mn. PMID:23594835

  11. Occupational and Environmental Exposure of Garage Workers and Taxi Drivers to Airborne Manganese Arising from the Use of Methylcyclopentadienyl Manganese Tricarbonyl in Unleaded Gasoline

    Microsoft Academic Search

    J. Zayed; M. Gérin; S. Loranger; P. Sierra; D. Bégin; G. Kennedy

    1994-01-01

    Occupational and environmental exposure to airborne manganese has been measured for two groups of workers in Montreal, taxi drivers and garage mechanics. In Canada methylcyclopentadienyl manganese tricarbonyl (MMT) has replaced lead as an anti-knock agent in gasoline and represents a potentially important source of manganese contamination for the population in general and for the two chosen groups of workers in

  12. Effect of the temperature of calcination on the catalytic performance of manganese- and samarium-manganese-based oxides in the complete oxidation of acetone

    Microsoft Academic Search

    A. Gil; L. M. Gandía; S. A. Korili

    2004-01-01

    The effect of the calcination temperature on manganese-based catalysts used in the complete oxidation of acetone has been studied. The catalysts, containing manganese and samarium and being in bulk oxide form, were prepared in the laboratory and calcined at 673, 823, 1073 and 1273K. The calcination temperature controls and modifies the type of single manganese oxide present, the development of

  13. Manganese Based Oxidative Technologies For Water/Wastewater Treatment 

    E-print Network

    Desai, Ishan

    2013-08-27

    and structural properties of ferrites. These laboratory prepared catalysts were thoroughly characterized using XRD, SEM, TEM, HR-TEM, and BET. Their magnetic properties have also been studied. These manganese ferrites offer the potential to enhance hydroxyl...

  14. Manganese, Iron, and sulfur cycling in Louisiana continental shelf sediments

    EPA Science Inventory

    Sulfate reduction is considered the primary pathway for organic carbon remineralization on the northern Gulf of Mexico Louisiana continental shelf (LCS) where bottom waters are seasonally hypoxic, yet limited information is available on the importance of iron and manganese cyclin...

  15. Electrochromic reactions in manganese oxides I. Raman analysis

    SciTech Connect

    Bernard, M.C.; Hugot-Le Goff, A.; Thi, B.V. (Univ. Pierre et Marie Curie, Paris (France). UPR 15 du CNRS Physique des Liquides et Electrochimie); Cordoba de Torresi, S. (Univ. Estadual de Campinas (Brazil). Dept. de Fisica Aplicada)

    1993-11-01

    Like nickel oxide, manganese oxide is a widely studied material in the primary batteries field. The reactions taking place during voltametric cycling of manganese oxides can be determined using in situ Raman spectroscopy. The main difficulty for the oxide identification is to obtain relevant Raman reference spectra because of the many possible compounds and, for some of these compounds, of their instability in the laser beam. As a consequence, several modifications of different tetra-, tri- and divalent manganese oxides and oxyhydroxides were carefully studied. The electrochromic behavior of three types of manganese oxides, two prepared by thermal oxidations and the other by electrochemical deposition, were then compared. The presence of nonstoichiometry in the pristine material was necessary to obtain a reversible electrochromic effect. The reaction during electrochromic cycling is more complicated than a simple passage from MnO[sub 2] to MnOOH.

  16. Manganese resources of the Cuyuna range, east-central Minnesota

    SciTech Connect

    Beltrame, R.J.; Holtzman, R.C.; Wahl, T.E.

    1981-01-01

    The Cuyuna range, located in east-central Minnesota, consists of a sequence of argillite, siltstone, iron-formation, graywacke, slate, and quartzite of early Proterozoic age. Manganese-bearing materials occur within the iron-rich strata of the Trommald Formation and the Rabbit Lake Formation. Computer-assisted resource estimates, based on exploration drill hole information, indicate that the Cuyuna range contains a minimum of 176 million metric tons (MMT) of marginally economic manganiferous rock with an average grade of 10.46 weight percent manganese. The calculated 18.5 MMT of manganese on the Cuyuna range could supply this country's needs for this important and strategic metal for nearly 14 years. An additional resource of 6.9 MMT of manganese metal is available in the lower grade deposits The vast majority of these calculated resources are extractable by current surface mining techniques.

  17. The non-magnetic collapsed tetragonal phase of CaFe2As2 and superconductivity in the iron pnictides

    NASA Astrophysics Data System (ADS)

    Soh, J. H.; Tucker, G. S.; Pratt, D. K.; Abernathy, D. L.; Stone, M. B.; Ran, S.; Bud'Ko, S. L.; Canfield, P. C.; Kreyssig, A.; McQueeney, R. J.; Goldman, A. I.

    2014-03-01

    The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the non-superconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is non-magnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds. Work at the Ames Laboratory was supported by the Department of Energy, Basic Energy Sciences. Work at ORNL's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences.

  18. Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers.

    PubMed

    Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

    2015-01-01

    The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices. PMID:26020492

  19. Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers

    PubMed Central

    Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

    2015-01-01

    The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices. PMID:26020492

  20. In situ TiC-reinforced austenitic steel composite by self-propagating high temperature synthesis

    Microsoft Academic Search

    D. S. Gowtam; M. Ziyauddin; M. Mohape; S. S. Sontakke; V. P. Deshmukh; A. K. Shah

    2007-01-01

    TiC-reinforced austenitic steel composites have been prepared by self-propagating high temperature synthesis (SHS). The in\\u000a situ reinforcement of a Fe-Mn-based austenitic steel matrix with TiC was achieved upon aluminothermic reduction of iron oxide\\u000a (Fe2O3), manganese dioxide (MnO2) and titanium dioxide (TiO2) powders in the presence of carbon (C). This highly exothermic thermite reaction was found to produce in situ the

  1. Metallic solvent extraction of manganese and titanium from ferroalloys

    Microsoft Academic Search

    A. J. Godsell; D. J. Fray

    1990-01-01

    The selective removal of valuable elements from ferroalloys has been investigated. It has been found that liquid bismuth is\\u000a a suitable solvent for leaching manganese from its ferroalloy. High recoveries and rapid reaction rates were obtained for\\u000a low-carbon ferromanganese, but results for the high-carbon ferromanganese and silicomanganese were less favorable due to the\\u000a lower activity of manganese in these alloys

  2. Manganese-Zinc-Ferrites with Improved Magnetic and Mechanical Properties

    Microsoft Academic Search

    H. Baumgartner; J. Dreikorn; R. Dreyer; L. Michalowsky; E. Pippel; J. Woltersdorf

    1997-01-01

    The 3-component system of manganese-zinc-ferrites is being thoroughly investigated as regards its intrinsic properties. The macroscopic properties of these spinel are variable within broad limits over the process of microstructure formation. Oxides of the 3d and 4d elements are frequently used as additives to determine the temperature dependence of the initial permeability and the electrical conductivity of manganese-zinc-ferrites. Additives for

  3. The Molecular Geomicrobiology of Bacterial Manganese(II) Oxidation

    Microsoft Academic Search

    Bradley M. Tebo; Kati Geszvain; Sung-Woo Lee

    \\u000a Manganese is the second most abundant transition metal found in the Earth’s crust. It has a significant biological role as\\u000a it is a cofactor of enzymes such as superoxide dismutase and is the key metal in the reaction center of photosystem II. In\\u000a the environment, manganese is mostly found in three different oxidation states: II, III, and IV. Mn(II), primarily

  4. Manganese exposure: Neuropsychological and neurological symptoms and effects in welders

    Microsoft Academic Search

    Rosemarie M. Bowler; Sabine Gysens; Emily Diamond; Sanae Nakagawa; Marija Drezgic; Harry A. Roels

    2006-01-01

    Manganese exposure reportedly may have an adverse effect on CNS function and mood. Sixty-two welders with clinical histories of exposure to manganese were compared to 46 matched regional controls chosen at random from a telephone directory. The following tests were given: Wechsler Adult Intelligence Scale (WAIS-III), Wechsler Memory Scale (WMS-III), Boston Naming, WRAT-3, Cancellation H, Trail Making Tests A and

  5. Lithium Isotope Selectivity of Sorbents Prepared from Lithium Manganese Oxides

    Microsoft Academic Search

    HIROTSUGU TAKEUCHI; TAKAO OI; MORIKAZU HOSOE

    1999-01-01

    Sorbents are prepared by extracting lithium ions from lithium manganese oxides with the lithium\\/manganese mole ratio (Li\\/Mn ratio) varying between 0.42 and 0.84, and their lithium isotope selectivities are investigated. All the sorbents are Li-specific and the values of the Li-to-Li isotopic separation factor (S) are between 1.0040 and 1.0092 at 25°C. The S value is slightly dependent on the

  6. Electrochemical supercapacitor material based on manganese oxide: preparation and characterization

    Microsoft Academic Search

    Junhua Jiang; Anthony Kucernak

    2002-01-01

    A novel class of electrochemical supercapacitor electrode material has been electrochemically synthesized from a manganese halide complex in water-containing acetonitrile electrolyte at room temperature. This material has been physically and chemically characterized by scanning electron microscopy, X-ray photoelectron microscopy (XPS), FT-Raman microscopy and cyclic voltammetry. XPS and FT-Raman characterization suggest that this material is composed of manganese oxide with a

  7. Toxicity of Manganese to Ceriodaphnia dubia and Hyalella azteca

    Microsoft Academic Search

    P. J. Lasier; P. V. Winger; K. J. Bogenrieder

    2000-01-01

    .   Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments, and pore waters. Manganese\\u000a can be present at toxic levels in anoxic solutions due to increased solubility under chemically reducing conditions, and it\\u000a can remain at those levels for days in aerated test waters due to slow precipitation kinetics. Ceriodaphnia dubia and Hyalella azteca are freshwater

  8. Giant negative magnetoresistance in Manganese-substituted Zinc Oxide

    PubMed Central

    Wang, X. L.; Shao, Q.; Zhuravlyova, A.; He, M.; Yi, Y.; Lortz, R.; Wang, J. N.; Ruotolo, A.

    2015-01-01

    We report a large negative magnetoresistance in Manganese-substituted Zinc Oxide thin films. This anomalous effect was found to appear in oxygen-deficient films and to increase with the concentration of Manganese. By combining magnetoresistive measurements with magneto-photoluminescence, we demonstrate that the effect can be explained as the result of a magnetically induced transition from hopping to band conduction where the activation energy is caused by the sp-d exchange interaction. PMID:25783664

  9. Oxygen toxicity in Streptococcus mutans: manganese, iron and superoxide dismutase

    SciTech Connect

    Martin, M.E.; Strachan, R.C.; Aranha, H.; Evans, S.L.; Salin, M.L.; Welch, B.; Arceneaux, J.E.L.; Byers, B.R.

    1984-07-01

    When cultured anaerobically in a chemically defined medium that was treated with Chelex-100 to lower its trace metal content, Streptococcus mutans OMZ176 had no apparent requirement for manganese or iron. Manganese or iron was necessary for aerobic cultivation in deep static cultures. During continuous aerobic cultivation in a stirred chemostat, iron did not support the growth rate achieved with manganese. Since the dissolved oxygen level in the chemostat cultures was higher than the final level in the static cultures, manganese may be required for growth at elevated levels. In medium supplemented with manganese, cells grown anaerobically contained a low level of superoxide dismutase (SOD) activity; aerobic cultivation increased SOD activity at least threefold. In iron-supplemented medium, cells grown anaerobically also had low SOD activity; aerobic incubation resulted in little increase in SOD activity. Polyacrylamide gel electrophoresis of the cell extracts revealed a major band and a minor band of SOD activity in the cells grown with manganese; however, cells grown with iron contained a single band of SOD activity with an R/sub f/ value similar to that of the major band found in cells grown with manganese. None of the SOD activity bands were abolished by the inclusion of 2 mM hydrogen peroxide in the SOD activity strain. S. mutans may not produce a separate iron-containing SOD but may insert either iron or manganese into an apo-SOD protein. Alternatively, iron may function in another activity (not SOD) that augments the defense against oxygen toxicity at low SOD levels. 28 references, 3 figures, 1 table.

  10. Low Copper and High Manganese Levels in Prion Protein Plaques

    PubMed Central

    Johnson, Christopher J.; Gilbert, P.U.P.A.; Abrecht, Mike; Baldwin, Katherine L.; Russell, Robin E.; Pedersen, Joel A.; Aiken, Judd M.; McKenzie, Debbie

    2013-01-01

    Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of copper and increased levels of manganese are associated with disease. The objectives of this study were to: (1) assess copper and manganese levels in healthy and TSE-infected Syrian hamster brain homogenates; (2) determine if the distribution of these metals can be mapped in TSE-infected brain tissue using X-ray photoelectron emission microscopy (X-PEEM) with synchrotron radiation; and (3) use X-PEEM to assess the relative amounts of copper and manganese in prion plaques in situ. In agreement with studies of other TSEs and species, we found reduced brain levels of copper and increased levels of manganese associated with disease in our hamster model. We also found that the in situ levels of these metals in brainstem were sufficient to image by X-PEEM. Using immunolabeled prion plaques in directly adjacent tissue sections to identify regions to image by X-PEEM, we found a statistically significant relationship of copper-manganese dysregulation in prion plaques: copper was depleted whereas manganese was enriched. These data provide evidence for prion plaques altering local transition metal distribution in the TSE-infected central nervous system. PMID:23435237

  11. The content of manganese and iron in hip joint tissue.

    PubMed

    Brodziak-Dopiera?a, Barbara; Kwapuli?ski, Jerzy; Sobczyk, Krzysztof; Wiechu?a, Danuta

    2013-07-01

    Manganese and iron are elements that constitute components of bone tissue. The aim of this study was to determine presence of manganese and iron in hip joint tissue and interdependencies between these elements. The objects of the research were hip joint elements from people residing in cities on the territory of the Upper Silesian Industrial District. The number of people in the study group was 91 samples, including 66 samples from women and 25 from a man. The examined tissues were obtained intraoperatively during hip replacement procedures. The content of manganese and iron was determined using the atomic absorption spectrophotometry (AAS) method. The lowest content of manganese and iron was found in the cortical bone, and the largest, in the case of manganese, in the articular cartilage, whereas in the case of iron in a fragment of the cancellous bone from the intertrochanteric area. The content of iron in selected elements of the hip joint decreased with age. Higher content of manganese in hip joint tissue of women compared to men was confirmed. What is more, higher content of iron in hip joint tissue of men was confirmed as well. PMID:23415599

  12. Low copper and high manganese levels in prion protein plaques

    USGS Publications Warehouse

    Johnson, Christopher J.; Gilbert, P.U.P.A.; Abrecth, Mike; Baldwin, Katherine L.; Russell, Robin E.; Pedersen, Joel A.; McKenzie, Debbie

    2013-01-01

    Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of copper and increased levels of manganese are associated with disease. The objectives of this study were to: (1) assess copper and manganese levels in healthy and TSE-infected Syrian hamster brain homogenates; (2) determine if the distribution of these metals can be mapped in TSE-infected brain tissue using X-ray photoelectron emission microscopy (X-PEEM) with synchrotron radiation; and (3) use X-PEEM to assess the relative amounts of copper and manganese in prion plaques in situ. In agreement with studies of other TSEs and species, we found reduced brain levels of copper and increased levels of manganese associated with disease in our hamster model. We also found that the in situ levels of these metals in brainstem were sufficient to image by X-PEEM. Using immunolabeled prion plaques in directly adjacent tissue sections to identify regions to image by X-PEEM, we found a statistically significant relationship of copper-manganese dysregulation in prion plaques: copper was depleted whereas manganese was enriched. These data provide evidence for prion plaques altering local transition metal distribution in the TSE-infected central nervous system.

  13. Manganese micro-nodules on ancient brick walls.

    PubMed

    López-Arce, P; García-Guinea, J; Fierro, J L G

    2003-01-20

    Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the main construction material. Manganese micro-nodules (circa 2 microm in diameter) have grown under the external bio-film surface of the bricks. Recent anthropogenic activities such as industrial emissions, foundries, or traffic and housing pollution have further altered these old bricks. The energy-dispersive X-ray microanalyses (XPS) of micro-nodules show Al, Si, Ca, K, Fe and Mn, with some carbon species. Manganese atoms are present only as Mn(4+) and iron as Fe(3+) (FeOOH-Fe(2)O(3) mixtures). The large concentration of alga biomass of the River Tagus and the Torcón and Guajaraz reservoirs suggest manganese micro-nodules are formed either from water solutions rich in anthropogenic MnO(4)K in a reduction environment (from Mn(7+) to Mn(4+)) or by oxidation mechanisms from dissolved Mn(2+) (from Mn(2+) to Mn(4+)) linked to algae biofilm onto the ancient brick surfaces. Ancient wall surfaces were also studied by scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Chemical and biological analyses of the waters around Toledo are also analysed for possible sources of manganese. Manganese micro-nodules on ancient brick walls are good indicators of manganese pollution. PMID:12526915

  14. Numerical and Experimental Applications of TWIP Steel in Automotive Parts

    NASA Astrophysics Data System (ADS)

    Lee, J. W.; Lim, J. H.; Choi, J. B.; Oh, P. Y.

    2011-08-01

    Modern automotive design has been faced with the weight reduction problem to meet the CO2 emissions standard while achieving high safety and compact design. Such being the case, most car makers want to use the ultra high strength steels (UHSS). But there are several problems when such steels are used, due to presumed lack of formability. Since the disadvantage such as above, it has been suggested that UHSS need special forming methods or it should be used only limited process like simple bending, by many automotive research institutes. To overcome these shortcomings, Twinning Induced Plasticity (TWIP) steel for improved strength and formability has been developed by steel making company, including POSCO, Korea. Because of its characteristics, it is expected to be widely used in automotive parts. This paper aims at finding out several ways how to make effective use of TWIP steel in automotive parts. Especially, comprising about from 15 to 18% manganese and from 1.5 to 2% aluminum which was developed by POSCO for application of the automotive parts will be considered.

  15. Bioaccumulation of manganese and its toxicity in feral pigeons (Columba livia) exposed to manganese oxide dust (Mn3O4).

    PubMed

    Sierra, P; Chakrabarti, S; Tounkara, R; Loranger, S; Kennedy, G; Zayed, J

    1998-11-01

    Manganese tetroxide (Mn3O4) is a product from the combustion of methylcyclopentadienyl manganese tricarbonyl. Exposure to high levels of manganese can lead to serious health effects especially to the central nervous and respiratory systems. Very few studies on the effects of long-term low level exposure to Mn3O4 have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity of manganese in various organs of feral pigeons (Columba livia) when exposed to low levels of Mn3O4 via inhalation and hence to find any possible relationship between these two parameters. A total of 22 pigeons was exposed to 239 micrograms/m3 of manganese for 7 h/day, 5 days/week for 5, 9, and 13 consecutive weeks. Manganese concentrations in various tissues, e.g., brain (mesencephalon), lung, liver, intestine, pancreas, kidney, muscle, bone, and whole blood, were measured by neutron activation analysis. Various biochemical parameters in blood, e.g., hematocrit, total proteins, glucose, uric acid, alanine aminotransferase, total iron, blood urea nitrogen and triglycerides, were also measured. Manganese concentrations in brain, lung, and bone were significantly higher in Mn3O4-exposed pigeons (0.59, 0.58, and 3.02 micrograms wet tissue, respectively) than in the control group (0.46, 0.19, 1.74 micrograms/g wet tissue, respectively). However, except for total proteins such exposure did not produce any changes in various biochemical parameters which were within the normal values. Thus these results have shown that, despite significant bioaccumulation of manganese in some tissues, no significant toxic effects could be seen. PMID:9841807

  16. MANGANESE METABOLISM WITH ORAL AND INTRAVENOUS 54MN IN YOUNG CALVES AS INFLUENCED BY SUPPLEMENTAL MANGANESE 1

    Microsoft Academic Search

    J. C. Carter; W. J. Miller; M. W. Neathery; R. P. Gentry; P. E. Stake; D. M. Blackmon

    2010-01-01

    Summary Twelve young (average age - 4 days) male Holstein calves fed either whole milk or whole milk supplemented with 15 ppm manganese (Mn) were given either an oral or intravenous (iv) tracer 54 Mn dose. Manganese-supplemented calves excreted more (P< .01)54Mn in the feces than controls. Feeding supplemental Mn reduced S4Mn retention, as measured directly, by 73% (60.1 vs.

  17. THE STATE OF MANGANESE IN THE PHOTOSYNTHETIC APPARATUS: FIRST VIEW OF THE MANGANESE SITES BY X-RAY ABSORPTION SPECTROSCOPY

    SciTech Connect

    Kirby, Jon A.; Goodin, D.B.; Robertson, A.S.; Smith, J.P.; Thompson, A.C.; Klein, M.P.

    1980-11-01

    Manganese atoms have long been implicated as essential ingredients in photosynthetic oxygen evolution. Heretofore they have eluded direct observation. We report the first direct observation, by X-ray Absorption Spectroscopy, of the Mn sites in chloroplasts isolated from Spinacia oleracea. The manganese in chlorplasts is commonly thought to exist in two pools. The major pool, corresponding to two-thirds of the manganese, can be reversibly released with concomitant loss of oxygen evolving capacity, and has thus come to be assigned as the active pool. The role of the remanant one-third, or tightly bound pool is moot. Our analysis of the Extended X-ray Absorption Fine Structure of the active pool is consistent with a bridged dimeric structure involving two manganese atoms separated by about 2.7 {Angstroms}. The distance between manganese and bridging ligands is about 1.8 {Angstrom}. Analysis of the edge region suggests that the manganese in the active pool exists in oxidation states somewhat higher than Mn(II).

  18. Effects of a pulsed magnetic treatment on the fatigue of low carbon steel

    SciTech Connect

    Fahmy, Y.; Hare, T.; Conrad, H. [North Carolina State Univ., Raleigh, NC (United States). Materials Science and Engineering Dept.] [North Carolina State Univ., Raleigh, NC (United States). Materials Science and Engineering Dept.; Tooke, R. [Magnetic Processing Systems, Inc., Plymouth, MN (United States)] [Magnetic Processing Systems, Inc., Plymouth, MN (United States)

    1998-04-03

    Russian researchers in the early seventies reported that the presence of a magnetic field accelerated creep and the onset of tensile deformation in iron. Work in the mid-eighties by Bhat et. al. suggested that residually magnetized steels exhibit decreased wear-resistance when compared to non-magnetized counterparts. These results were attributed to magnetic strain-induced (magnetostrictive) interaction of dislocations with domain walls. More recently, Bhat et. al. reported that the fatigue life of mild steel in a sustained magnetic field decreased with increasing field strength. Fatigue life had a limiting minimum value when the magnetic field reached (or exceeded) the critical field strength required to induce magnetic saturation of the specimen. The work reported here on the influence of magnetic fields on mechanical properties was conducted on: (i) non-magnetized specimens in the presence of a sustained magnetic field or on (ii) magnetized specimens in the absence of a magnetic field. The effect of a repeated, pulsed magnetic field (applied to the specimen on an interrupted, during-service schedule) which results in zero net-magnetization has not been previously investigated. The objective of this study was therefore to determine the effect of a pulsed magnetic field (applied either at predetermined intervals or at a certain fraction of the normal fatigue life) on the fatigue life of low carbon steel.

  19. Glutamate/aspartate transporter (GLAST), taurine transporter and metallothionein mRNA levels are differentially altered in astrocytes exposed to manganese chloride, manganese phosphate or manganese sulfate.

    PubMed

    Erikson, Keith M; Suber, Robert L; Aschner, Michael

    2002-09-01

    Manganese (Mn)-induced neurotoxicity can occur due to environmental exposure (air pollution, soil, water) and/or metabolic aberrations (decreased biliary excretion). High brain manganese levels lead to oxidative stress, as well as alterations in neurotransmitter metabolism with concurrent neurobehavioral deficits. Based on the few existing studies that have examined brain regional Mn concentration, it is likely that in pathological conditions, Mn concentration can reach between 100 and 500 microM. Environmental Mn exposure as a result of methylcyclopentadienyl manganese tricarbonyl (MMT) combustion is in the form of phosphate or sulfate (MnPO4, MnSO4, respectively). Pharmacokinetic studies have shown that the Mn salt will determine the rate of transport into the brain: MnCl2 > MnSO4 > MnPO4. The salt-specific neurotoxicity of these species is unknown. The primary goal of this study was to examine gene expression of glutamate/aspartate transporter (GLAST), taurine transporter (tau-T), and metallothionein-I (MT-I) in astrocytes exposed to manganese chloride (MnCl2), manganese sulfate (MnSO4), and manganese phosphate (MnPO4). We hypothesized that the effects of MnPO4 and MnSO4 exposure on GLASTexpression in astrocytes would be similar to those induced by MnCl2, since irrespective of salt species exposure, once internalized by astrocytes, the Mn ion would be identically complexed. At the same time, we hypothesized that the magnitude of the effect would be salt-dependent, since the chemical speciation would determine the rate of intracellular uptake of Mn. MnCl2 caused a significant overall decrease (P < 0.0001) in astrocytic GLAST mRNA levels with MnSO4 causing a moderate decrease. MnPO4 exposure did not alter GLAST mRNA in astrocytes. We also sought to examine astrocytic metallothionein and taurine transporter gene expression as markers of manganese exposure. Our findings suggest that manganese chloride significantly decreased (P < 0.0001) astrocytic metallothionein mRNA compared to both the sulfate and phosphate species. However, astrocytic taurine transporter mRNA was not affected by Mn exposure, irrespective of the salt species. These data are consistent with the hypothesis that astrocytic neurotoxicity due to Mn exposure is dependent upon its species, with solubility, and by inference, intracellular concentration, representing a major determinant of its neurotoxicity. PMID:12387356

  20. Effects of high but nontoxic dietary manganese and iron on their metabolism by calves

    SciTech Connect

    Ho, S.Y.; Miller, W.J.; Gentry, R.P.; Neathery, M.W.; Blackmon, D.M.

    1984-07-01

    Sixteen male Holstein calves were fed one of four diets for 18 days in an experiment consisting of 0 and 1000 ppm supplemental manganese and 0 and 1000 ppm added iron as manganese carbonate and ferrous carbonate. The control diet contained 55 ppm manganese and 220 ppm iron. All calves were dosed orally 48 h prior to sacrifice with 500 ..mu..Ci of manganese-54. Small intestinal iron was less in calves fed a high manganese diet, a possible interaction of these two elements at the absorption site. Feeding a high manganese diet tended to decrease iron (total) concentrations in liver and pancreas. When the high manganese diet was supplemented with additional iron, antagonistic effects of manganese on iron were eliminated. Neither iron nor manganese concentrations in tissues were affected by an increase of dietary iron. Manganese-54 content of tissue was reduced by the high manganese diet but was not affected by dietary iron. Total manganese and iron in feces fairly closely reflected dietary intake of each element with no evidence of interaction. Calves fed the high iron diet excreted less manganese-54 in their feces over 2 days. Total iron in blood serum was not affected significantly by the dietary treatments. 22 references, 2 figures, 7 tables.

  1. Effects of high but nontoxic dietary manganese and iron on their metabolism by calves.

    PubMed

    Ho, S Y; Miller, W J; Gentry, R P; Neathery, M W; Blackmon, D M

    1984-07-01

    Sixteen male Holstein calves were fed one of four diets for 18 days in an experiment consisting of 0 and 1000 ppm supplemental manganese and 0 and 1000 ppm added iron as manganese carbonate and ferrous carbonate. The control diet contained 55 ppm manganese and 220 ppm iron. All calves were dosed orally 48 h prior to sacrifice with 500 muCi of manganese-54. Small intestinal iron was less in calves fed a high manganese diet, a possible interaction of these two elements at the absorption site. Feeding a high manganese diet tended to decrease iron (total) concentrations in liver and pancreas. When the high manganese diet was supplemented with additional iron, antagonistic effects of manganese on iron were eliminated. Neither iron nor manganese concentrations in tissues were affected by an increase of dietary iron. Manganese-54 content of tissue was reduced by the high manganese diet but was not affected by dietary iron. Total manganese and iron in feces fairly closely reflected dietary intake of each element with no evidence of interaction. Calves fed the high iron diet excreted less manganese-54 in their feces over 2 days. Total iron in blood serum was not affected significantly by the dietary treatments. PMID:6747050

  2. Six-coordinate manganese(3+) in catalysis by yeast manganese superoxide dismutase

    SciTech Connect

    Sheng, Yuewei; Gralla, Edith Butler; Schumacher, Mikhail; Cascio, Duilio; Cabelli, Diane E.; Valentine, Joan Selverstone (EWHA); (UCLA); (BNL)

    2012-10-10

    Reduction of superoxide (O{sub 2}{sup -}) by manganese-containing superoxide dismutase occurs through either a 'prompt protonation' pathway, or an 'inner-sphere' pathway, with the latter leading to formation of an observable Mn-peroxo complex. We recently reported that wild-type (WT) manganese superoxide dismutases (MnSODs) from Saccharomyces cerevisiae and Candida albicans are more gated toward the 'prompt protonation' pathway than human and bacterial MnSODs and suggested that this could result from small structural changes in the second coordination sphere of manganese. We report here that substitution of a second-sphere residue, Tyr34, by phenylalanine (Y34F) causes the MnSOD from S. cerevisiae to react exclusively through the 'inner-sphere' pathway. At neutral pH, we have a surprising observation that protonation of the Mn-peroxo complex in the mutant yeast enzyme occurs through a fast pathway, leading to a putative six-coordinate Mn3+ species, which actively oxidizes O{sub 2}{sup -} in the catalytic cycle. Upon increasing pH, the fast pathway is gradually replaced by a slow proton-transfer pathway, leading to the well-characterized five-coordinate Mn{sup 3+}. We here propose and compare two hypothetical mechanisms for the mutant yeast enzyme, diffeeing in the structure of the Mn-peroxo complex yet both involving formation of the active six-coordinate Mn{sup 3+} and proton transfer from a second-sphere water molecule, which has substituted for the -OH of Tyr34, to the Mn-peroxo complex. Because WT and the mutant yeast MnSOD both rest in the 2+ state and become six-coordinate when oxidized up from Mn{sup 2+}, six-coordinate Mn{sup 3+} species could also actively function in the mechanism of WT yeast MnSODs.

  3. Process for desulfurizing steel

    Microsoft Academic Search

    P. J. Koros; R. G. Petrushka

    1982-01-01

    A process for desulfurizing molten steel includes the formation of a synthetic slag layer, the formation of a cover which occludes the ambient air, and the simultaneous injection of lime and a reactant agent which vaporizes within the molten steel.

  4. Stress Corrosion Cracking Behavior of Cast Stainless Steels

    SciTech Connect

    Teysseyre, Sebastien [University of Michigan; Busby, Jeremy T [ORNL; Was, Gary [University of Michigan

    2009-01-01

    Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not detrimental to SCC resistance.

  5. OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE

    E-print Network

    Sparks, Donald L.

    OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J. Lafferty All Rights Reserved #12;OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J. Lafferty Approved

  6. Indirect Magnetic Coupling of Manganese Porphyrin to a Ferromagnetic Cobalt Substrate D. Chylarecka,

    E-print Network

    Aeschlimann, Martin

    Indirect Magnetic Coupling of Manganese Porphyrin to a Ferromagnetic Cobalt Substrate D. Chylarecka (DFT+U) calculations, for the magnetic coupling of manganese(II) porphyrin (MnP) molecules to thin Co

  7. Manganese accumulation in nail clippings as a biomarker of welding fume exposure and neurotoxicity.

    PubMed

    Sriram, Krishnan; Lin, Gary X; Jefferson, Amy M; Roberts, Jenny R; Andrews, Ronnee N; Kashon, Michael L; Antonini, James M

    2012-01-27

    Occupational exposure to welding fumes (WF) is thought to cause Parkinson's disease (PD)-like neurological dysfunction. An apprehension that WF may accelerate the onset of PD also exists. Identifying reliable biomarkers of exposure and neurotoxicity are therefore critical for biomonitoring and neurological risk characterization of WF exposure. Manganese (Mn) in welding consumables is considered the causative factor for the neurological deficits seen in welders. Hence, we sought to determine if Mn accumulation in blood or nail clippings can be a marker for adverse exposure and neurotoxicity. To model this, rats were exposed by intratracheal instillation to dissolved or suspended fume components collected from gas metal arc-mild steel (GMA-MS) or manual metal arc-hard surfacing (MMA-HS) welding. Trace element analysis revealed selective Mn accumulation in dopaminergic brain areas, striatum (STR) and midbrain (MB), following exposure to the two fumes. This caused dopaminergic abnormality as evidenced by loss of striatal tyrosine hydroxylase (Th; 25-32% decrease) and Parkinson disease (autosomal recessive, early onset) 7 (Park7; 25-46% decrease) proteins. While blood Mn was not detectable, Mn levels in nails strongly correlated with the pattern of Mn accumulation in the striatum (R(2)=0.9386) and midbrain (R(2)=0.9332). Exposure to manganese chloride (MnCl(2)) caused similar Mn accumulation in STR, MB and nail. Our findings suggest that nail Mn has the potential to be a sensitive and reliable biomarker for long-term Mn exposure and associated neurotoxicity. The non-invasive means by which nail clippings can be collected, stored, and transported with relative ease, make it an attractive surrogate for biomonitoring WF exposures in occupational settings. PMID:22085607

  8. Manganese Is Essential for Neuronal Health.

    PubMed

    Horning, Kyle J; Caito, Samuel W; Tipps, K Grace; Bowman, Aaron B; Aschner, Michael

    2015-07-17

    The understanding of manganese (Mn) biology, in particular its cellular regulation and role in neurological disease, is an area of expanding interest. Mn is an essential micronutrient that is required for the activity of a diverse set of enzymatic proteins (e.g., arginase and glutamine synthase). Although necessary for life, Mn is toxic in excess. Thus, maintaining appropriate levels of intracellular Mn is critical. Unlike other essential metals, cell-level homeostatic mechanisms of Mn have not been identified. In this review, we discuss common forms of Mn exposure, absorption, and transport via regulated uptake/exchange at the gut and blood-brain barrier and via biliary excretion. We present the current understanding of cellular uptake and efflux as well as subcellular storage and transport of Mn. In addition, we highlight the Mn-dependent and Mn-responsive pathways implicated in the growing evidence of its role in Parkinson's disease and Huntington's disease. We conclude with suggestions for future focuses of Mn health-related research. PMID:25974698

  9. Manganese homeostasis and utilization in pathogenic bacteria.

    PubMed

    Juttukonda, Lillian J; Skaar, Eric P

    2015-07-01

    Manganese (Mn) is a required cofactor for all forms of life. Given the importance of Mn to bacteria, the host has devised strategies to sequester Mn from invaders. In the macrophage phagosome, NRAMP1 removes Mn and other essential metals to starve intracellular pathogens; in the extracellular space, calprotectin chelates Mn and Zn. Calprotectin-mediated Mn sequestration is a newly appreciated host defense mechanism, and recent findings are highlighted herein. In order to acquire Mn when extracellular concentrations are low, bacteria have evolved efficient Mn acquisition systems that are under elegant transcriptional control. To counteract Mn overload, some bacteria possess Mn-specific export systems that are important in vivo, presumably for control of intracellular Mn levels. Mn transporters, their transcriptional regulators and some Mn-requiring enzymes are necessary for virulence of certain bacterial pathogens, as revealed by animal models of infection. Furthermore, Mn is an important facet of the cellular response to oxidative stress, a host antibacterial strategy. The battle for Mn between host and pathogen is now appreciated to be a major determinant of the outcome of infection. In this MicroReview, the contribution of Mn to the host-pathogen interaction is reviewed, and key questions are proposed for future study. PMID:25898914

  10. Stabilization of cubic zirconia with manganese oxide

    SciTech Connect

    Dravid, V.P.; Ravikumar, V. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering); Notis, M.R.; Lyman, C.E. (Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering); Dhalenne, G.; Revcolevschi, A. (Univ. de Paris-Sud, Orsay (France). Lab. de Chimie des Solides)

    1994-10-01

    A directionally solidified eutectic (DSE) of MnO-ZrO[sub 2] has been investigated using a variety of electron optical techniques. It is found that considerable MnO goes into ZrO[sub 2] to form a substitutional solid solution. About 14 wt% of MnO is soluble in ZrO[sub 2] close to the eutectic temperature. The solubility of ZrO[sub 2] in MnO, however, is quite low, less than 0.50 wt%. Electron diffraction experiments indicate that ZrO[sub 2] (MnO) has the cubic fluorite structure. Diffuse scattering, similar to other cubic zirconias (e.g., CaO, MgO stabilized zirconia), is also observed in manganese-stabilized zirconia. Diffuse scattering indicates the presence of oxygen vacancies and thus confirms the defect nature of the fluorite structure. Electron energy loss spectrometry (EELS) fine structure analysis of the Mn L[sub 23] edge provided clear evidence that Mn is present as Mn[sup 2+] in Mn-stabilized cubic ZrO[sub 2].

  11. Electrical behavior of natural manganese dioxide (NMD)

    SciTech Connect

    Gorgulho, H.F. [Fundacao de Ensino Superior de Sao Joao del Rei, Minas Gerais (Brazil); Fernandes, R.Z.D.; Pernaut, J.M. [Univ. Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil)

    1996-12-31

    NMD samples from Brazil have been submitted to magnetic and particle size separations and characterized by X-ray diffraction and fluorescence and thermogravimetric analyses. Results showed that simple physical treatments can lead to more than 60% enriched MnO{sub 2} materials which could satisfy some electrochemical applications. The electrical properties of the samples conditioned as pressed pellets have been investigated by four-points direct current probe and impedance spectroscopy, varying the conditions of preparation and measurement. It is proposed that the higher frequency impedance is equivalent to the intrinsic electronic resistance of the MnO{sub 2} phases while at lower frequencies occurs an interphase charge separation coupled with a possible ionic transport. The corresponding contact resistance depends on the particle size distribution of the material, the compactation pressure of pellets and the iron content of the materials. The interphase dielectric relaxation does not behave ideally; the depression of the impedance semicircles as shown in the Nyquist plane is assumed to be related to the roughness of the bulk interfaces. Recent developments have shown the possibility of using manganese oxides as reversible electrodes for battery or supercapacitor applications for electrical vehicle. In these perspectives it is important to study the electrical and electrochemical properties of NMD in order to estimate its suitability for this kind of applications.

  12. Manganese alters rat brain amino acids levels

    PubMed Central

    Santos, Dinamene; Batoreu, M. Camila; Almeida, Isabel; Ramos, Ruben; Sidoryk-Wegrzynowicz, M.; Aschner, Michael; Marreilha dos Santos, A.P.

    2012-01-01

    Manganese (Mn) is an essential element and it acts as a cofactor for a number of enzymatic reactions, including those involved in amino acid, lipid, protein and carbohydrate metabolism. Excessive exposure to Mn can lead to poisoning, characterized by psychiatric disturbances and an extrapyramidal disorder. Mn-induced neuronal degeneration is associated with alterations in amino acids metabolism. In the present study, we analyzed whole rat brain amino acid content subsequent to 4 or 8 intraperitoneal (ip) injections, with 25 mg MnCl2/kg/day, at 48-hour (h) intervals. We noted a significant increase in glycine brain levels after 4 or 8 Mn injections (p<0.05 and p<0.01, respectively) and arginine also after 4 or 8 injections (p<0.001). Significant increases were also noted in brain proline (p<0.01), cysteine (p<0.05), phenylalanine (p<0.01) and tyrosine (p<0.01) levels after 8 Mn injections vs. the control group. These findings suggest that Mn-induced alterations in amino acid levels secondary to Mn affect the neurochemical milieu. PMID:22971893

  13. Manganese Superoxide Dismutase: Guardian of the Powerhouse

    PubMed Central

    Holley, Aaron K.; Bakthavatchalu, Vasudevan; Velez-Roman, Joyce M.; St. Clair, Daret K.

    2011-01-01

    The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as ?-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component. PMID:22072939

  14. Redundancy among manganese peroxidases in Pleurotus ostreatus.

    PubMed

    Salame, Tomer M; Knop, Doriv; Levinson, Dana; Yarden, Oded; Hadar, Yitzhak

    2013-04-01

    Manganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. In Pleurotus ostreatus (the oyster mushroom) these enzymes are encoded by a gene family comprising nine members, mnp1 to -9 (mnp genes). Mn(2+) amendment to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn(2+)-amended glucose-peptone medium, mnp3, mnp4, and mnp9 were the most highly expressed mnp genes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed, mnp3 expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn(2+)-sufficient cultures, mnp3 was inactivated via the ?ku80 strain-based P. ostreatus gene-targeting system. In Mn(2+)-sufficient medium, inactivation of mnp3 did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn(2+)-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of either mnp4 or mnp9 did not affect orange II decolorization ability. These results indicate functional redundancy within the P. ostreatus MnP gene family, enabling compensation upon deficiency of one of its members. PMID:23377936

  15. Steel slag in acid mine drainage treatment and control

    SciTech Connect

    Ziemkiewicz, P.; Skousen, J.

    1999-07-01

    Steel slags are composed of calcium alumino-silicate oxides. Most slags have a sandy texture, but others have a silty texture and give a fine, powdery feel. Neutralization potentials of steel slags range from 45 to 78%, which make them candidates for neutralizing the acidity in acid mine drainage. Analysis of total metal content in Mingo Junction steel slab shows high concentrations of aluminum, chromium, iron, manganese, and titanium. Upon leaching this slag with water, the leachate had a pH of 11.7 and n alkalinity of 1,450 mg/L as CaCO{sub 3} equivalent. In general, steel slag yielded more alkalinity than equal weights of limestone (500 to 1,500 mg/L compared to 60 to 80 mg/L) during leaching studies. Leaching the slag with water and a weak sulfuric acid solution showed that the metals contained in the slag were not readily leachable since these metals were found at low concentrations in the leachate. When different amounts of slag were mixed with an acid-producing coal refuse and then leached with water, pH values of the leachate varied between 3.5 and 7.3. Slightly elevated levels of selenium, nickel, manganese, and possibly iron were found in leachates of refuse/slag mixtures compared to refuse alone. Due to slag's high availability in some areas and low cost, steel slags show potential as an acid-neutralizing material for coal refuse and acid-producing spoils, and for treating acid mine drainage directly. If slag is to be used as an alkaline amendment, it must be added in sufficient quantities to ensure nonacid conditions now and in the future, since under acid conditions some metals may become available. Steel slag can also be used as a liming material for soils. The most promising use for steel slag is as a source of alkalinity to fresh waters that may subsequently encounter acid mine drainage, such as alkaline leach beds or limestone sand applications to headwater streams.

  16. Manganese and acute paranoid psychosis: a case report

    PubMed Central

    2011-01-01

    Introduction Manganese regulates many enzymes and is essential for normal development and body function. Chronic manganese intoxication has an insidious and progressive course and usually starts with complaints of headache, fatigue, sleep disturbances, irritability and emotional instability. Later, several organ systems may be affected and, due to neurotoxicity, an atypical parkinsonian syndrome may emerge. With regard to neuropsychiatry, an array of symptoms may develop up to 30 years after intoxication, of which gait and speech abnormalities, cognitive and motor slowing, mood changes and hallucinations are the most common. Psychotic phenomena are rarely reported. Case presentation We describe the case of a 49-year-old Caucasian man working as a welder who was referred to our facility for evaluation of acute paranoid psychotic behavior. Our patient's medical history made no mention of any somatic complaints or psychiatric symptoms, and he had been involved in a professional career as a metalworker. On magnetic resonance imaging scanning of his brain, a bilateral hyperdensity of the globus pallidus, suggestive for manganese intoxication, was found. His manganese serum level was 52 to 97 nmol/L (range: 7 to 20 nmol/L). A diagnosis of organic psychotic disorder due to manganese overexposure was made. His psychotic symptoms disappeared within two weeks of treatment with low-dose risperidone. At three months later, serum manganese was decreased to slightly elevated levels and the magnetic resonance imaging T1 signal intensity was reduced. No signs of Parkinsonism were found and a definite diagnosis of manganese-induced apathy syndrome was made. Conclusion Although neuropsychiatric and neurological symptoms caused by (chronic) manganese exposure have been reported frequently in the past, in the present day the disorder is rarely diagnosed. In this report we stress that manganese intoxication can still occur, in our case in a confined-space welder, and may present clinically with a paranoid psychotic state that necessitates a rapid diagnostic procedure in order to avoid the permanent structural brain damage that may occur with chronic exposure. PMID:21486469

  17. Welding Rustproof Steels

    NASA Technical Reports Server (NTRS)

    Hoffmann, W

    1929-01-01

    The following experimental results will perhaps increase the knowledge of the process of welding rustproof steels. The experiments were made with two chrome-steel sheets and with two chrome-steel-nickel sheets having the composition shown in Table I.

  18. Blood manganese concentrations among first-grade schoolchildren in two South African cities

    Microsoft Academic Search

    Halina Röllin; Angela Mathee; Jonathan Levin; Penny Theodorou; Francois Wewers

    2005-01-01

    Little information exists on the environmental exposures to low levels of organometallic manganese (a principal combustion product from manganese-containing fuel additives) and public health. This study was undertaken to establish biological and environmental levels of manganese among first-grade schoolchildren in the South African cities of Johannesburg and Cape Town. The study was undertaken subsequent to partial introduction of the manganese-containing

  19. Estimating distributions of long-term particulate matter and manganese exposures for residents of Toronto, Canada

    Microsoft Academic Search

    C. A. Clayton; E. D. Pellizzari; C. E. Rodes; R. E. Mason; L. L. Piper

    1999-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT), a manganese-based gasoline additive, has been used in Canadian gasoline for about 20yr. Because MMT potentially increases manganese levels in particulate matter resulting from automotive exhausts, a population-based study conducted in Toronto, Canada assessed the levels of personal manganese exposures. Integrated 3-day particulate matter (PM2.5) exposure measurements, obtained for 922 participant periods over the course of

  20. Characteristics of manganese-coated sand using SEM and EDAX analysis

    Microsoft Academic Search

    Po-Yu Hu; Yung-Hsu Hsieh; Jen-Ching Chen; Chen-Yu Chang

    2004-01-01

    Manganese-coated sand” is a type of silica medium coated with manganese oxides, formed from the sorption of manganese oxides during long-term filtration via the process of rapid sand filtration, followed by aeration in a water treatment plant. Locally available manganese-coated sand, both for packing and as a byproduct of filtration processes for water treatment plants in Taiwan, was found to

  1. Studies on the Manganese-Mediated Isomerization of Alkynyl Carbonyls to

    E-print Network

    Lepore, Salvatore D.

    -butoxide. The mechanism of methylcyclopentadienyl manganese tricarbonyl (MMT) complexation to alkyne A has beenStudies on the Manganese-Mediated Isomerization of Alkynyl Carbonyls to Allenyl Carbonyls Salvatore@fau.edu Received May 24, 2005 A study of the role of base in the isomerization of manganese- coordinated conjugated

  2. Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system

    E-print Network

    Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system Kangkang, University of Michigan, Ann Arbor, MI 48109, U.S.A. ABSTRACT Ferromagnetic delta-phase manganese gallium to their potential for novel spintronics applications such as spin light-emitting diodes[1] . Delta phase manganese

  3. 75 FR 70583 - Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New Use Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ...RIN 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New...identified as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1), which...rule issued for cobalt lithium manganese nickel oxide (PMN P-04-269; CAS No....

  4. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Manganese strontium oxide (MnSrO3). 721.10008 Section...Substances § 721.10008 Manganese strontium oxide (MnSrO3 ). (a) Chemical...chemical substance identified as manganese strontium oxide (MnSrO3 ) (PMN...

  5. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Manganese strontium oxide (MnSrO3). 721.10008 Section...Substances § 721.10008 Manganese strontium oxide (MnSrO3 ). (a) Chemical...chemical substance identified as manganese strontium oxide (MnSrO3 ) (PMN...

  6. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 false Manganese strontium oxide (MnSrO3). 721.10008 Section...Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical...chemical substance identified as manganese strontium oxide (MnSrO3 ) (PMN...

  7. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Manganese strontium oxide (MnSrO3). 721.10008 Section...Substances § 721.10008 Manganese strontium oxide (MnSrO3 ). (a) Chemical...chemical substance identified as manganese strontium oxide (MnSrO3 ) (PMN...

  8. Effects of high but nontoxic dietary manganese and iron on their metabolism by calves

    Microsoft Academic Search

    S. Y. Ho; W. J. Miller; R. P. Gentry; M. W. Neathery; D. M. Blackmon

    1984-01-01

    Sixteen male Holstein calves were fed one of four diets for 18 days in an experiment consisting of 0 and 1000 ppm supplemental manganese and 0 and 1000 ppm added iron as manganese carbonate and ferrous carbonate. The control diet contained 55 ppm manganese and 220 ppm iron. All calves were dosed orally 48 h prior to sacrifice with 500

  9. Olfactory uptake of manganese requires DMT1 and is enhanced by anemia

    Microsoft Academic Search

    Khristy Thompson; Ramon M. Molina; Thomas Donaghey; James E. Schwob; Joseph D. Brain; Marianne Wessling-Resnick

    2006-01-01

    Manganese, an essential nutrient, can also elicit toxicity in the central nervous system (CNS). The route of exposure strongly influences the potential neurotoxicity of manganese-containing compounds. Recent studies suggest that inhaled manganese can enter the rat brain through the olfactory system, but little is known about the molecular factors involved. Divalent metal transporter-1 (DMT1) is the major trans- porter responsible

  10. Steel penetration in sand molds. Final technical report, September 1994--September 1997

    SciTech Connect

    Hayes, K.D.; Owens, M.; Barlow, J.; Stefanescu, D.M.; Lane, A.M.; Piwonka, T.S.

    1997-12-01

    The research program was successful in identifying the major factoirs that influence penetration. This was done first through a case study of penetration samples. The study revealed that both chemical and mechanical penetration were present in carbon and high manganese steels. It also found that only mechanical penetration is found in stainless steel samples. It should be noted that when mechanical penetration does occur, there is a greater risk of chemical reactions with the mold. Therefore, it is common to confuse mechanical penetration with chemical. Sessile drop experiments were run to discover the effect of steel chemistry on the contact angle for different substrates. These experiments revealed the best substrates for each type of metal. Bauxite, magnesite, and mullite were discovered to be the best materials for resisting mechanical penetration. It was also shown that high manganese steels cannot be poured into silica molds and that stainless steel should not be poured in chromite molds. The sessile drop data was used to develop a mechanical penetration model which correctly predicted penetration in sixteen of twenty castings poured at the University of Alabama. Mold/metal atmosphere tests were run to understand the effects of the atmosphere on chemical penetration. It was found that the chemistry affecting penetration has its greatest effect as the casting is just poured. Chemical penetration for low carbon steels cannot be completely eliminated by adding carbon (seacoal) to green sand molds although a marked decrease is obtained in its severity. Extremely high carbon concentrations might be able to totally eliminate the penetration but are not used because of their possible diffusion into the steel causing carburization. A chemical penetration model was produced and its results agree well with the experimental results.

  11. Eddy Current Simulations and Measurements of Sodium Effect for Magnetic and Non-Magnetic Steam Generator Tubes of Fbr

    NASA Astrophysics Data System (ADS)

    Mihalache, Ovidiu; Yamaguchi, Toshihiko; Ueda, Masashi; Miyahara, Shinya

    2009-03-01

    In fast breeder reactor (FBR), the steam generator (SG) tube wall is the only barrier between water steam and sodium flow. Eddy current signal (ECT) from outer tube defect is modified by both SG support plates (SP) as well as by sodium layer and unknown sodium drops located on the outer SG tube surface. In the present paper, ECT finite element simulations are conducted to evaluate sodium structures ECT noise and variations of defect and tube support plate signal in the presence of a thin layer covering the SG tube surface. Numerical simulations are validated and calibrated with experimental measurements of artificial outer defect for both magnetic and non-magnetic SG tubes in the absence or presence of sodium covering the outer surface of SG tubes. The papers presents also details about measurements of sodium structures (drops, layer) formed on the outer SG tube surface when these are soaked in a test tank filled with sodium at high temperatures (500° C) up to two hours.

  12. Enhanced magnetic and electrical properties in amorphous Ge:Mn thin films by non-magnetic codoping

    SciTech Connect

    Yin Wenjing; Kell, Copeland D.; Duska, Chris; Lu Jiwei; Floro, Jerrold A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); He Li; Hull, Robert [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Dolph, Melissa C. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Wolf, Stuart A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2012-02-01

    Amorphous Ge{sub 1-x}Mn{sub x} thin films have been prepared by co-depositing Ge and Mn on SiO{sub 2}/Si using an ultrahigh vacuum molecular beam epitaxy system. Across a range of growth temperatures and Mn concentrations (2.8 at. %, 10.9 at. %, and 21.3 at. %), we achieved enhanced magnetic and electrical properties with non-magnetic codopants dispersed in the films. Self-assembled Mn-rich amorphous nanostructures were observed in the amorphous Ge matrix, either as isolated nanoclusters or as nanocolumns, depending on Mn concentration. The ferromagnetic saturation moments were found to increase with Mn concentration and reached a maximum of 0.7 {mu}{sub B}/Mn in the as-grown samples. Two magnetic transition temperatures around 15 K and 200 K were observed in these amorphous MBE-grown samples. Coercivity is considered within the context of local magnetic anisotropy. The anomalous Hall effect confirmed a strong correlation between the magnetization and transport properties, indicating that global ferromagnetic coupling was carrier-mediated rather than through direct exchange. In addition, negative magnetoresistance was detected from 5 K to room temperature.

  13. Manganese, arsenic, and infant mortality in Bangladesh: an ecological analysis.

    PubMed

    Cherry, Nicola; Shaik, Kashem; McDonald, Corbett; Chowdhury, Zafrullah

    2010-01-01

    Recent studies in Bangladesh indicate that arsenic and manganese in tube-well water may increase the incidence of infant mortality. The study reported here examined whether these findings could be replicated. Data available from some 600 villages under the care of the nongovernmental organization (NGO) Gonoshasthaya Kendra included details of 29744 live births and 934 infant deaths in a 2-year period, with age and cause. These were analyzed by mean well levels of arsenic and manganese as reported by the British Geological Survey for the 12 upazillas. Odds ratios were calculated by age at death and cause. The effect of arsenic on all-cause infant mortality, although small and not significant, was consistent with earlier reports. The previous finding of an increased risk of infant mortality at concentrations of manganese > or =0.4 mg/L was not evident. PMID:20705575

  14. Metallic solvent extraction of manganese and titanium from ferroalloys

    NASA Astrophysics Data System (ADS)

    Godsell, A. J.; Fray, D. J.

    1990-04-01

    The selective removal of valuable elements from ferroalloys has been investigated. It has been found that liquid bismuth is a suitable solvent for leaching manganese from its ferroalloy. High recoveries and rapid reaction rates were obtained for low-carbon ferromanganese, but results for the high-carbon ferromanganese and silicomanganese were less favorable due to the lower activity of manganese in these alloys and the lack of wetting by liquid bismuth. Antimony was found to be a suitable solvent for titanium from ferrotitanium but iron was also taken into solution. Manganese was successfully transferred from solution in liquid bismuth to liquid aluminum by fused salt electrorefining, using a NaCl-KCl-MnCl electrolyte, at high current efficiencies with negligible carryover of bismuth.

  15. Risk assessment of an essential element: manganese.

    PubMed

    Santamaria, Annette B; Sulsky, Sandra I

    2010-01-01

    Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Mn is present in most tissues of all living organisms and is present naturally in rocks, soil, water, and food. High-dose oral, parenteral, or inhalation exposures are associated with increased tissue Mn levels that may lead to development of adverse neurological, reproductive, or respiratory effects. Manganese-induced clinical neurotoxicity is associated with a motor dysfunction syndrome commonly referred to as manganism. Because Mn is an essential element and absorption and excretion are homeostatically regulated, a reasonable hypothesis is that there should be no adverse effects at low exposures. Therefore, there should be a threshold for exposure, below which adverse effects may occur only rarely, if at all, and the frequency of occurrence of adverse effects may increase with higher exposures above that threshold. Lowest-observed-adverse-effect levels (LOAELs), no-observed-adverse-effect levels (NOAELs), and benchmark dose levels (BMDs) have been derived from studies that were conducted to evaluate subclinical neurotoxicity in human occupational cohorts exposed to Mn. Although there is some uncertainty about the predictive value of the subclinical neuromotor or neurobehavioral effects that were observed in these occupational cohort studies, results of the neurological tests were used in risk assessments to establish guidelines and regulations for ambient air levels of Mn in the environment. A discussion of the uncertainties associated with these tests is provided in this review. The application of safety and uncertainty factors result in guidelines for ambient air levels that are lower than the LOAELs, NOAELs, or BMDs from occupational exposure studies by an order of magnitude, or more. Specific early biomarkers of effect, such as subclinical neurobehavioral or neurological changes or magnetic resonance imaging (MRI) changes, have not been established or validated for Mn, although some studies attempted to correlate certain biomarkers with neurological effects. Pharmacokinetic studies with rodents and monkeys provide valuable information about the absorption, bioavailability, and tissue distribution of various Mn compounds with different solubilities and oxidation states in different age groups. These pharmacokinetic studies showed that rodents and primates maintain stable tissue Mn levels as a result of homeostatic mechanisms that tightly regulate absorption and excretion of ingested Mn and limit tissue uptake at low to moderate levels of inhalation exposure. In addition, physiologically based pharmacokinetic (PBPK) models are being developed to provide for the ability to conduct route-to-route extrapolations, evaluate nasal uptake to the central nervous system (CNS), and determine life-stage differences in Mn pharmacokinetics. Such models will facilitate more rigorous quantitative analysis of the available human pharmacokinetic data for Mn and will be used to identify situations that may lead to increased brain accumulation related to altered Mn kinetics in different human populations, and to develop quantitatively accurate predictions of elevated Mn levels that may serve as a basis of dosimetry-based risk assessments. Such dosimetry-based risk assessments will permit for the development of more scientifically refined and robust recommendations, guidelines, and regulations for Mn levels in the ambient environment and occupational settings. PMID:20077284

  16. Lake destratification and speciation of iron and manganese.

    PubMed

    Chiswell, B; Zaw, M

    1991-10-01

    A long-term study of the effect of artificial aeration (destratification) of a water storage dam upon the speciation of iron and manganese in the dam waters has been undertaken. Separation of dam samples into soluble and insoluble forms by selective membrane filtration was undertaken before using the techniques of EPR spectroscopy, ion chromatography and gel filtration to assess the speciation of soluble species, and selective extraction and surface analysis (ESCA, SIMS and SEM) techniques to determine the speciation of particulate iron and manganese species. The percentages of soluble iron and manganese before (1983-85) and after (1986-88) artificial aeration are compared for the periods Jan-Dec, Jan-Mar, and Jun-Aug at three depths 6 m, 15 m and 0.5 m above the dam base, to assess the importance of seasonal changes in the various depths of the dam. Although aeration had an initial marked reduction in levels of soluble iron and manganese at all depths of the dam, the concentrations of these mtals showed a steady increase over succeeding years. Analysis of the figures over summer and winter periods shows that the reduction of soluble iron was maintained in summer, but not during winter. Upon aeration, the initial reduction of soluble manganese concentration was maintained in succeeding years in the epilimnic regions of the dam, but not in the hypolimnion. Statistical analysis of data has been undertaken to correlate the changes in relationship between the various forms of iron and manganese with the advent of aeration. PMID:24233959

  17. Alloying element vaporization and weld pool temperature during laser welding of AlSl 202 stainless steel

    Microsoft Academic Search

    P. A. A. Khan; T. Debroy

    1984-01-01

    Alloying element vaporization rates, plasma composition, and the changes in weld composition during laser welding of 202 stainless\\u000a steel are discussed in this paper. Iron, manganese, and chromium were the most dominant species in the plasma. During laser\\u000a welding it is always a difficult task to measure the temperature of the weld pool since this region is surrounded by hot

  18. Manganese and the Evolution of Photosynthesis

    NASA Astrophysics Data System (ADS)

    Fischer, Woodward W.; Hemp, James; Johnson, Jena E.

    2015-05-01

    Oxygenic photosynthesis is the most important bioenergetic event in the history of our planet—it evolved once within the Cyanobacteria, and remained largely unchanged as it was transferred to algae and plants via endosymbiosis. Manganese plays a fundamental role in this history because it lends the critical redox behavior of the water-oxidizing complex of photosystem II. Constraints from the photoassembly of the Mn-bearing water-oxidizing complex fuel the hypothesis that Mn(II) once played a key role as an electron donor for anoxygenic photosynthesis prior to the evolution of oxygenic photosynthesis. Here we review the growing body of geological and geochemical evidence from the Archean and Paleoproterozoic sedimentary records that supports this idea and demonstrates that the oxidative branch of the Mn cycle switched on prior to the rise of oxygen. This Mn-oxidizing phototrophy hypothesis also receives support from the biological record of extant phototrophs, and can be made more explicit by leveraging constraints from structural biology and biochemistry of photosystem II in Cyanobacteria. These observations highlight that water-splitting in photosystem II evolved independently from a homodimeric ancestral type II reaction center capable of high potential photosynthesis and Mn(II) oxidation, which is required by the presence of homologous redox-active tyrosines in the modern heterodimer. The ancestral homodimer reaction center also evolved a C-terminal extension that sterically precluded standard phototrophic electron donors like cytochrome c, cupredoxins, or high-potential iron-sulfur proteins, and could only complete direct oxidation of small molecules like Mn2+, and ultimately water.

  19. Grain boundary segregation in boron added interstitial free steels studied by 3-dimensional atom probe

    SciTech Connect

    Seto, K. [Kawasaki Steel Corp., Chiba (Japan). Technical Research Labs.] [Kawasaki Steel Corp., Chiba (Japan). Technical Research Labs.; Larson, D.J.; Warren, P.J.; Smith, G.D.W. [Univ. of Oxford (United Kingdom). Dept. of Materials] [Univ. of Oxford (United Kingdom). Dept. of Materials

    1999-04-09

    The development of deep-drawable sheet steels is of particular significance for the automotive industry. Titanium and/or niobium added extra-low carbon interstitial free (IF) steels are key materials. The virtually complete removal of carbon and nitrogen should lead to superior forming properties. However, the lack of solute carbon at grain boundaries significantly decreases the bonding force at the interfaces, which often causes intergranular brittle fracture when deeply drawn steel sheets are subjected to impact deformation at low temperature. This phenomenon is called secondary working embrittlement (SWE), and is a major problem when solute atoms such as phosphorus, manganese or silicon are added to increase the tensile strength of the steels. Small amounts of boron, which does not affect the formability of the steels significantly, are usually added as a remedial measure in such cases. The 3-dimensional atom probe (3DAP) combined with field ion microscopy (FIM) has the ability to produce 3-dimensional images from regions approximately 20nm*20nm*100nm in size, and identify each atomic species and the relative location of each atom with nearly lattice resolution. In this study, a combination of these methods was applied to produce FIM tips of IF steel containing grain boundaries. The authors report here the first observations of the segregation of boron in IF steels using 3DAP.

  20. Transuranic interfacial reaction studies on manganese oxidemineral surfaces

    SciTech Connect

    Shaughnessy, Dawn A.; Nitsche, Heino; Serne, R. Jeffrey; Shuh,David K.; Waychunas, Glenn A.; Booth, Corwin H.; Cantrell, Kirk J.

    2002-05-15

    Several DOE sites have been contaminated by transuranicradionuclide (TRU) discharges including neptunium and plutonium. Theirinteraction with the surrounding geological media can affect thetransport and remediation of these radionuclides in the environment.Manganese based minerals, present as minor phases in the vadose zone, canpreferentially sequester TRU over other minerals present in largerquantities. The objective of this project is to understand theinteractions between plutonium and neptunium and manganese oxyhydroxideminerals to predict potential hazards they represent to the environment,as well as to provide important scientific information for the design ofeffective remediation strategies for contaminated DOE sites.

  1. Biochemical changes in pulmonary cells following manganese oxide inhalation

    SciTech Connect

    Adkins, B. Jr. (Northrop Services, Inc., Research Triangle Park, NC); Luginbuhl, G.H.; Gardner, D.E.

    1980-03-01

    Inhalation of manganese oxide (Mn dose, 879.0 ..mu..g/m/sup 3/) for 2 h reduced the total number of alveolar macrophages obtained by endotracheal lavage in pulmonary cell populations, slightly reduced cellular viability, and reduced both phagocytic capability and total protein in sonicated pulmonary cells. Increases in intracellular adenosine triphosphate and acid phosphatase specific activity were also exhibited by the pulmonary cells, but sonicated cells obtained from the exposed mice showed no change in lactic acid dehydrogenase specific activity. A slight increase in extracellular protein in the fluid phase of the lavage suspension was observed after manganese oxide exposure.

  2. [The clinical picture and diagnosis of manganese-induced parkinsonism].

    PubMed

    Petkova, V; Karadzhov, K

    1991-01-01

    As a result of 5-year-long electromyographic observation of 144 persons engaged in ferroalloy production, the parkinsonism syndrome was diagnosed in 4 persons. The disease development was slow, gradual, with the muscular tension growth against the asthenovegetative symptoms. This particularity did not correspond to the traditional view of the three-stage development of chronic manganese intoxication prior to the acute phase of manganese parkinsonism. The contributors hold that the stretch reflex proved to be the most early-stage oriented, prognostically and diagnostically reliable among the other electromyographic techniques. PMID:1879747

  3. Manganese Encephalopathy among Ephedron Abusers-Case Reports.

    PubMed

    Janocha-Litwin, Justyna; Marianska, Katarzyna; Serafinska, Sylwia; Simon, Krzysztof

    2014-09-26

    Ephedrone encephalopathy is referred to as a group of symptoms of manganese deposition within the central nervous system (CNS), resulting from the abuse of ephedrone (methcathinone), obtained in reaction using the excess amount of manganese-containing oxidants. The diagnosis is based on the contrast-enhanced head MRI findings characteristic for this syndrome, clinical manifestation and history of ephedrone use. The syndrome has been reported in recent years in young people from Eastern Europe and Russia with a history of ephedrone overuse. However, no report has ever been published on ephedrone encephalopathy in Polish patients. PMID:25255816

  4. Manganese-Induced Parkinsonism due to Ephedrone Abuse.

    PubMed

    Sikk, Katrin; Haldre, Sulev; Aquilonius, Sten-Magnus; Taba, Pille

    2011-01-01

    During recent years, a syndrome of hypokinesia, dysarthria, dystonia, and postural impairment, related to intravenous use of a "designer" psychostimulant derived from pseudoephedrine using potassium permanganate as the oxidant, has been observed in drug addicts in several countries in Eastern Europe with some cases also in Western countries. A levodopa unresponsive Parkinsonian syndrome occurs within a few months of abusing the homemade drug mixture containing ephedrone (methcathinone) and manganese. The development of this neurological syndrome has been attributed to toxic effects of manganese, but the role of the psychostimulant ephedrone is unclear. This paper describes the clinical syndrome, results of neuroimaging, and therapeutic attempts. PMID:21403909

  5. Comparative response of poppy (Papaver somniferum L.) and eight crop and vegetable species to manganese excess in solution culture

    Microsoft Academic Search

    T. B. Koen

    1982-01-01

    The relative response of poppy (Papaver somniferum L.) and eight crop and vegetable species to excess manganese was investigated in a glasshouse, solution culture experiment. Plant yields and manganese concentrations were measured after two and six weeks growth at five levels of manganese (10–800 ?M). Poppies were highly sensitive to manganese toxicity in solution culture and reductions in shoot yield

  6. Environmental contamination and human exposure to manganese--contribution of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline.

    PubMed

    Zayed, J; Vyskocil, A; Kennedy, G

    1999-01-01

    The organomanganese compound MMT (methylcyclopentadienyl manganese tricarbonyl), an antiknock additive in unleaded gasoline, has been used in Canada since 1976. Indeed, Canada is the only country where MMT is almost exclusively used. In October 1995, by court decision the Environmental protection Agency (EPA) granted Ethyl's waiver for the use of MMT in the United States. Paradoxically, in 1997 the federal government of Canada adopted a law (C-29) that banned both the interprovincial trade and the importation for commercial purposes of manganese-based substances, including MMT. However, MMT is currently widely used in Canada because of substantial stockpiling, and six Canadian provinces are challenging the law in the courts. Moreover, MMT has been approved for use in Argentina, Australia, Bulgaria, Russia, and conditionally, in New Zealand. It has been suggested by some scientists that combustion of MMT may be a significant source of exposure to inorganic Mn in urban areas. The crucial question is whether Mn contamination from industrial sources combined with the additional contamination that would result from the widespread use of MMT would lead to toxic effects. Our research efforts have attempted to assess the environmental/ecosystem Mn contamination arising from the combustion of MMT in abiotic and biotic systems as well as human exposure. The experimental evidence acquired so far provides useful information on certain environmental consequences of the use of MMT as well as raising a number of questions. Our results gave evidence indicating that roadside air, soils, plants, and animals may be contaminated by Mn. As well, some specific groups of the population could have a higher level of exposure to Mn. Nevertheless, the levels of exposure remain below international guide values. Further studies and further characterization of dose-response relationships are thus needed to provide successful implementation of evidence-based risk-assessment approaches. PMID:10029224

  7. Manganese deficiency and toxicity: are high or low dietary amounts of manganese cause for concern?

    PubMed

    Finley, J W; Davis, C D

    1999-01-01

    Manganese is an essential trace element that is required for the activity of several enzymes. Manganese is also quite toxic when ingested in large amounts, such as the inhalation of Mn-laden dust by miners. This review examines Mn intake by way of the food supply and poses the question: Is there reason to be concerned with Mn toxicity or deficiency in free-living populations in North America? Although much remains to be learned of the functions of Mn, at present there are only a few vaguely described cases of Mn deficiency in the medical literature. Given the heterogeneity of the North American food supply, it is difficult to see the possibility of more than greatly isolated and unique instances of Mn deficiency. However, low Mn-dependent superoxide dismutase activity may be associated with cancer susceptibility, and deserves further study. There may be reasons, however, to be concerned about Mn toxicity under some very specialized conditions. Increasing numbers of young people are adopting a vegetarian lifestyle which may greatly increase Mn intake. Iron deficiency may increase Mn absorption and further increase the body-burden of Mn, especially in vegetarians. Mn is eliminated primarily through the bile, and hepatic dysfunction could depress Mn excretion and further contribute to the body burden. Would such a combination of events predispose substantial numbers of people to chronic Mn toxicity? At present, there is no definite proof of this occurring, but given the state of knowledge at the present time, more studies with longer time-frames and more sensitive methods of analysis are needed. PMID:10475586

  8. Application of pharmacokinetic data to the risk assessment of inhaled manganese.

    PubMed

    Dorman, David C; Struve, Melanie F; Clewell, Harvey J; Andersen, Melvin E

    2006-09-01

    There is increased interest within the scientific community concerning the neurotoxicity of manganese owing in part to the use of methylcyclopentadienyl manganese tricarbonyl (MMT) as a gasoline fuel additive and an enhanced awareness that this essential metal may play a role in hepatic encephalopathy and other neurologic diseases. Neurotoxicity generally arises over a prolonged period of time and results when manganese intake exceeds its elimination leading to increases in brain manganese concentration. Neurotoxicity can occur following high dose oral, inhalation, or parenteral exposure or when hepatobiliary clearance of this metal is impaired. Studies completed during the past several years have substantially improved our understanding of the health risks posed by inhaled manganese by determining exposure conditions that lead to increased concentrations of manganese within the central nervous system and other target organs. Many of these studies focused on phosphates, sulfates, and oxides of manganese since these are formed and emitted following MMT combustion by an automobile. These studies have evaluated the role of direct nose-to-brain transport of inhaled manganese and have examined differences in manganese toxicokinetics in potentially sensitive subpopulations (e.g., fetuses, neonates, individuals with compromised hepatic function or sub-optimal manganese intake, and the aged). This manuscript reviews the U.S. Environmental Protection Agency's current risk assessment for inhaled manganese, summarizes these contemporary pharmacokinetic studies, and considers how these data could inform future risk assessments of this metal following inhalation. PMID:16644014

  9. Time to Re-evaluate the Guideline Value for Manganese in Drinking Water?

    PubMed Central

    Ljung, Karin; Vahter, Marie

    2007-01-01

    Objective We reviewed the scientific background for the current health-based World Health Organization (WHO) guideline value for manganese in drinking water. Data sources and extraction The initial starting point was the background document for the development of the WHO’s guideline value for manganese in drinking water as well as other regulations and recommendations on manganese intake levels. Data referred to in these documents were traced back to the original research papers. In addition, we searched for scientific reports on manganese exposure and health effects. Data synthesis The current health-based guideline value for manganese in drinking water is based partly on debatable assumptions, where information from previous reports has been used without revisiting original scientific articles. Presently, preparation of common infant formulas with water containing manganese concentrations equivalent to the WHO guideline value will result in exceeding the maximum manganese concentration for infant formula. However, there are uncertainties about how this maximum value was derived. Concurrently, there is increasing evidence of negative neurologic effects in children from excessive manganese exposure. Conclusions The increasing number of studies reporting associations between neurologic symptoms and manganese exposure in infants and children, in combination with the questionable scientific background data used in setting the manganese guideline value for drinking water, certainly warrant a re-evaluation of the guideline value. Further research is needed to understand the causal relationship between manganese exposure and children’s health, and to enable an improved risk assessment. PMID:18007980

  10. THE STATE OF MANGANESE IN THE PHOTOSYNTHETIC APPARATUS. I. EXAFS STUDIES ON CHLOROPLASTS AND di-u-oxo BRIDGED di-MANGANESE MODEL COMPOUNDS

    SciTech Connect

    Kirby, J.A.; Robertson, A.S.; Smith, J.P.; Thompson, A.C.; Thompson, A.C.; Klein, M.P.

    1980-11-01

    Extended X-ray Absorption Fine Structure (EXAFS) studies on the manganese contained in spinach chloroplasts and on certain di-u-oxo bridged manganese dimers of the form (X{sub 2}Mn)O{sub 2}(MnX{sub 2} (X=2,2'-bypyridine and 1,10-phenanthroline) are reported. From these studies, the manganese associated with photosynthetic oxygen evolution is suggested to occur as a bridged transition metal dimer with most likely another manganese. Extensive details on the analysis are included.

  11. Exposure to Environmental Air Manganese and Medication Use

    EPA Science Inventory

    Manganese (Mn) is an essential element with natural low levels found in water, food, and air, but due to industrialized processes, both workplace and the environmental exposures to Mn have increased. Recently, environmental studies have reported physical and mental health problem...

  12. Aqueous ferrofluids based on manganese and cobalt ferrites

    Microsoft Academic Search

    Francisco Augusto Tourinho; Raymonde Franck; René Massart

    1990-01-01

    Synthesis of two new aqueous ferrofluids is performed chemically according to Massart's procedure. Manganese and cobalt ferrite magnetic particles are precipitated and treated in order to obtain colloidal sols by creating a charge density on their surface. Such “ionic” ferrofluids can be prepared in an acidic (after a treatment by ferric nitrate) or in an alkaline medium at a concentration

  13. Manganese cluster in photosynthesis: Where plants oxidize water to dioxygen

    Microsoft Academic Search

    Vittal K. Yachandra; M. P. Klein; K. Sauer

    1996-01-01

    The essential involvement of manganese in photosynthetic water oxidation was implicit in the observation by Pirson in 1937 that plants and algae deprived of Mn in their growth medium lost the ability to evolve Oâ. Addition of this essential element to the growth medium resulted in the restoration of water oxidation within 30 min. There is increased interest in the

  14. Diagnosis and correction of manganese deficiency in corn

    Microsoft Academic Search

    H. J. Mascagni Jr; F. R. Cox

    1984-01-01

    Although manganese (Mn) deficiency in soybeans (Glycine max) has been recognized on the Atlantic Coastal Plain, it has not been well recognized in corn (Zea mays) until recent years. Hence, there is a lack of information relating to the diagnosis and correction of Mn deficiency in corn. Field experiments were conducted to determine if the Mn soil test interpretation for

  15. Manganese tolerance and accumulation in six Mn hyperaccumulators or accumulators

    Microsoft Academic Search

    Peng Liu; Xiumei Tang; Chunfeng Gong; GenDi Xu

    2010-01-01

    This study used hydroponics cultivation to investigate the manganese (Mn) accumulation and tolerance abilities of six species—Phytolacca americana L., Poa annua L., Comnyza canadensis L., Cynodon dactylon L., Polygonum hydropiper L., and Polygonum perfoliatum L. We found that P. perfoliatum, P. hydropiper, and P. americana were Mn-hyperaccumulators and that P. perforliatum have superior Mn accumulation and toleration abilities over the

  16. Biological Indicator of Manganese54 Contamination in Terrestrial Environments

    Microsoft Academic Search

    Raffaele Cavalloro; Oscar Ravera

    1966-01-01

    THE value of Unio molluscs as indicators of manganese-54 contamination in freshwater environments has been discussed in an earlier communication1. We have attempted to find a similar indicator for terrestrial environments, and have concluded that the red slug Arion rufus, L. (Gasteropoda, Stylommatophora), may fulfil this role.

  17. SPECIATION OF METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL AND ITS DERIVATIVES: A REVIEW

    Microsoft Academic Search

    David J. Butcher

    2002-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organomanganese compound that is used as an octane enhancer for gasoline and other fuels. The widespread use of this compound has been suggested to be harmful to human health. In order to accurately assess its impact, high sensitivity instrumentation for the determination of MMT and its derivatives is required. In this paper, three instrumental

  18. Innovative Trends in Marine Management: Hawaii's Manganese Crust Work Group

    Microsoft Academic Search

    John C. Wiltshire

    1984-01-01

    In spite of tight funding, Hawaii has been the location of a number of innovative ocean technologies. These have been facilitated by the coordination of university researchers, industry representatives, Federal agencies, and State officials. An excellent example of this new trend in marine management is the recently formed Joint State-Federal Manganese Crust Work Group. Funded by the U.S. Department of

  19. Community Exposure to Air Manganese and Motor and Cognitive Outcomes

    EPA Science Inventory

    Although manganese (Mn) is an essential nutrient, occupational studies have shown inhaling high levels of Mn can lead to adverse nervous system health effects. Few studies have examined the health effects of air-Mn exposure on adults in a community. We conducted a cross-sectional...

  20. Discovery of Chromium, Manganese, Nickel, and Copper Isotopes

    E-print Network

    K. Garofali; R. Robinson; M. Thoennessen

    2010-12-07

    Twenty-seven chromium, twenty-five manganese, thirty-one nickel and twenty-six copper isotopes have so far been observed and the discovery of these isotopes is discussed. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  1. Accommodation of rare-earths and manganese by apatite

    Microsoft Academic Search

    Michael Gaft; Renata Reisfeld; Gerard Panczer; Georges Boulon; Shlomo Shoval; Bernard Champagnon

    1997-01-01

    Time-resolved luminescence allows the differences between rare-earth elements and manganese accommodation in apatites to be distinguished. The valence state and exact crystal site of incorporated cations are interpreted from the spectral characteristics. Contrary to the apriory incorporated cations, the adsorbed species can be revealed only after high temperature diffusion.

  2. Elements of the iron and manganese cycles in Lake Baikal

    USGS Publications Warehouse

    Granina, L.Z.; Callender, E.

    2007-01-01

    Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time of renewal, etc.). Some previous results and common concepts were critically reevaluated. ?? Pleiades Publishing, Ltd. 2007.

  3. Effect on Microcystis Aeruginosa Inactivation by Manganese Copper Composited Algaecide

    Microsoft Academic Search

    Zhao Liang; Li Xing; Liang Shuang; Yang Yan-Ling

    2009-01-01

    Manganese copper composited algaecide (MCC) was prepared by permanganate and acid-soluble copper chloride. The effectiveness of MCC on Microcystis aeruginosa removal and the effective period of MCC were studied, pH influence on the water sample was inspected, and the feasibility of MCC as a new algaecide was discussed. The results showed that inactivation effect on Microcystis aeruginosa by MCC was

  4. Effect of ascorbic acid and other adjuvants on manganese absorption

    Microsoft Academic Search

    R. Papaioannou; A. Sohler; C. C. Pfeiffer

    1986-01-01

    Animal experiments have demonstrated that manganese is poorly absorbed from the gut and that it is rapidly removed from the blood by liver uptake and bilary excretion. Zinc supplements which are readily absorbed can induce a Mn deficiency so that Mn supplementation is necessary. Supplementation with a diet rich in Mn (high in legumes, nuts, whole grains, tea) failed to

  5. How pharmacokinetic modeling could improve a risk assessment for manganese

    EPA Science Inventory

    The neurotoxicity of manganese (Mn) is well established, yet the risk assessment of Mn is made complex by certain enigmas. These include apparently greatertoxicity via inhalation compared to oral exposure and greater toxicity in humans compared to rats. In addition, until recentl...

  6. The Magnetocrystalline Anisotropy of Cobalt-Substituted Manganese Ferrite

    Microsoft Academic Search

    R F Pearson

    1959-01-01

    The first order anisotropy constant K1 has been measured by torque methods on substituted manganese ferrite crystals containing 1, 2, 4, 6, 8, 10 and 25 mol% cobalt ferrite from 160° to 300°K. The contribution to the anisotropy from the cobalt ions is found to vary linearly with cobalt concentration up to 25%. The extrapolated contributions of the cobalt ions

  7. Estimating Air-Manganese Exposures in Two Ohio Towns

    EPA Science Inventory

    Manganese (Mn), a nutrient required for normal metabolic function, is also a persistent air pollutant and a known neurotoxin at high concentrations. Elevated exposures can result in a number of motor and cognitive deficits. Quantifying chronic personal exposures in residential po...

  8. Ferromagnetic resonance in cobalt doped magnesium and manganese ferrites

    Microsoft Academic Search

    M. Rosenbloom; R. W. Teale

    1971-01-01

    Measurements of the change in anisotropy field and ferromagnetic resonance linewidth due to doping magnesium ferrite and manganese ferrite with cobalt are reported. A large effect upon anisotropy and relatively small effect on the linewidth is observed. The behaviour is explained in a broadly satisfactory manner in terms of a ion theory of the anisotropy and the longitudinal relaxation model,

  9. MANGANESE DIOXIDE COATED FILTERS FOR REMOVING RADIUM FROM DRINKING WATER

    EPA Science Inventory

    Research was performed using manganese dioxide (MnO2) to demonstrate that above pH3 cations are adsorbed from solution in the order of their affinity, and that the interaction is characterized by the pH dependence of the metal. The relationship of the zero point charge of pH and ...

  10. Nanoprecipitates in Steels

    Microsoft Academic Search

    Joachim H Schneibel; Bimal Kad

    2008-01-01

    The creep strength of ferritic steels can be substantially improved by the incorporation of a high number density of nano-scale dispersoids. Examples for such alloys are the oxide dispersion strengthened steels MA956, MA957, and PM2000. The dispersoids in these steels contain Y and Ti, or Y and Al. They can be as small as a few nanometers in size. Processing

  11. Nanoprecipitates in Steels

    Microsoft Academic Search

    Joachim H Schneibel; Zhao Ping Lu; Sang Hoon Shim

    2007-01-01

    The creep strength of ferritic steels can be substantially improved by the incorporation of a high number density of nano-scale dispersoids. Examples for such alloys are the oxide dispersion strengthened steels MA956, MA957, and PM2000. The dispersoids in these steels contain Y and Ti, or Y and Al. They can be as small as a few nanometers in size. Processing

  12. Numerical Approaches of Cluster Statistics for Stochastic Manganese Deposits

    NASA Astrophysics Data System (ADS)

    Bayirli, Mehmet

    2014-11-01

    In terms of origin, the most important manganese deposits are sedimentary deposits which grow on the surface and/or fractures of the natural magnesite ore. They reveal various morphological characteristic according to their location in origin. Some of them may be fractal in appearance. Although several studies have been completed with regards to their growth mechanism, it may be safe to say that their cluster statistics and scaling properties have rarely been subject an academic scrutiny. Hence, the subject of this study has been designed to calculate cluster statistics of manganese deposits by first; transferring the images of manganese deposits into a computer and then scaling them with the help of software. Secondly, the root-mean square (rms) thickness (also called as expected value in systems), the number of particles, clusters and cluster sizes are computed by means of scaling method. In doing so it has been found that the rms thickness and the number of particles are in correlation, a result which is called as power-law behaviour, T~N-? (the critical exponent is computed as ? = 1.743). It has also been found that the correlation between the number of clusters and their sizes are determined with the power-law behaviour n(s)~s-? (the critical exponent t may vary between 1.054 and 1.321). Finally, the distribution functions of natural manganese clusters on the magnesite subtract have been determined. All that may point to the fact that the manganese deposits may be formed according to a Poisson distribution. The results found and the conclusion reached in this study may be used to compare various natural deposits in geophysics.

  13. Associations of welding and manganese exposure with Parkinson disease

    PubMed Central

    Borenstein, Amy R.; Nelson, Lorene M.

    2012-01-01

    Objective: To examine associations of welding and manganese exposure with Parkinson disease (PD) using meta-analyses of data from cohort, case-control, and mortality studies. Methods: Epidemiologic studies related to welding or manganese exposure and PD were identified in a PubMed search, article references, published reviews, and abstracts. Inclusion criteria were 1) cohort, case-control, or mortality study with relative risk (RR), odds ratio (OR), or mortality OR (MOR) and 95 confidence intervals (95% CI); 2) RR, OR, and MOR matched or adjusted for age and sex; 3) valid study design and analysis. When participants of a study were a subgroup of those in a larger study, only results of the larger study were included to assure independence of datasets. Pooled RR/OR estimates and 95% CIs were obtained using random effects models; heterogeneity of study effects were evaluated using the Q statistic and I2 index in fixed effect models. Results: Thirteen studies met inclusion criteria for the welding meta-analysis and 3 studies for the manganese exposure meta-analysis. The pooled RR for the association between welding and PD for all study designs was 0.86 (95% CI 0.80–0.92), with absence of between-study heterogeneity (I2 = 0.0). Effect measures for cohort, case-control, and mortality studies were similar (0.91, 0.82, 0.87). For the association between manganese exposure and PD, the pooled OR was 0.76 (95% CI 0.41–1.42). Conclusions: Welding and manganese exposure are not associated with increased PD risk. Possible explanations for the inverse association between welding and PD include confounding by smoking, healthy worker effect, and hormesis. PMID:22965675

  14. Electron Energy-Loss Safe-Dose Limits for Manganese Valence Measurements in Environmentally Relevant Manganese Oxides

    E-print Network

    Sparks, Donald L.

    Electron Energy-Loss Safe-Dose Limits for Manganese Valence Measurements in Environmentally-Claire Gaillot, and Donald L. Sparks The High-Resolution Analytical Electron Microbeam Facility+). In this study, the effects of beam damage during electron energy-loss spectroscopy (EELS) in the transmission

  15. Carbon deposition from a ?-irradiated CO 2/CO/CH 4/C 2H 6 gas mixture on the manganese oxides MnO, Mn 3O 4 and Mn 2O 3

    NASA Astrophysics Data System (ADS)

    Allen, G. C.; Hallam, K. R.

    1997-12-01

    The composition of oxides formed on steel surfaces within power reactors may influence heat transfer efficiency. Previous studies have indicated that carbon is deposited on spinal-type oxides containing manganese, iron, cobalt, nickel and chromium. In this investigation, characterised manganese oxides have been subjected to ?-irradiation under conditions similar to those experienced in reactors in an effort to understand the catalytic processes involved in deposit initiation and growth. Mn 3O 4 and Mn 2O 3, under the conditions present in the ?-cell, were reduced to MnO during the time of exposure. Relative carbon deposition rates were observed to follow the trend MnO>Mn 3O 4?Mn 2O 3.

  16. Sorption behaviour of manganese-coated calcined-starfish and manganese-coated sand for Mn(II).

    PubMed

    Lee, Seung-Mok; Kim, Won-Gee; Yang, Jae-Kyu; Tiwari, Diwakar

    2010-04-01

    The objective of the present investigation was to explore the sorption behaviour of manganese-coated samples of calcined starfish (MCCSF) (i.e. the impregnation of calcined starfish with manganese) for the removal of low levels of an important heavy metal toxic ion, Mn(II), from aqueous solutions. The suitability of this solid was further compared with two different samples of manganese-coated sands (MCS): MCS4 and MCS9 impregnated at pH 4.0 and pH 9.0, respectively. These comparative studies were performed in both batch and column experiments. Batch data indicated that a fairly good stability of the coating was obtained for these three samples in the pH region 2.5 to 10.0. The removal efficiency of MCCSF was fairly good in comparison with the MCS4 and MCS9 samples. These last two samples possessed similar Mn(II) removal capacities. Moreover, a small dose of sodium hypochlorite further enhanced the uptake of Mn(II) by these solids. The sorbate concentration dependence data fitted reasonably well to the Freundlich adsorption isotherm. The column data indicated that MCCSF possessed a relatively higher adsorption capacity compared with the MCS4 and MCS9 samples. The breakthrough curves obtained were then used to evaluate the apparent removal capacity of these solids under the dynamic conditions using the Thomas equation. The SEM images obtained for these manganese-coated solids along with the virgin base materials, i.e. sand and calcined starfish, showed that manganese oxides occupied the surfaces or pores of the base materials and formed clusters on the base surface. PMID:20450119

  17. Modeling the environmental fate of manganese from methylcyclopentadienyl manganese tricarbonyl in urban landscapes.

    PubMed

    Bhuie, A K; Ogunseitan, O A; White, R R; Sain, M; Roy, D N

    2005-03-01

    The environmental impacts of gasoline additives such as lead (Pb) and Methyl Tertiary Butyl Ether (MTBE) are well documented, leading to the phasing out of these additives. In contrast, little is known about the health and environmental impacts of potential replacement chemicals such as Methylcyclopentadienyl Manganese Tricarbonyl (MMT). The combustion of MMT in gasoline leads to the formation of MnPO4 and MnSO4 and MMT is considered a recent source of inorganic Mn in urban landscapes particularly in high traffic areas. The main objective of this study is to estimate the automotive deposition of Mn from MMT relative to the traffic volume at sites near a major highway in the Greater Toronto Area of Canada, where MMT is currently being used. Manganese emission levels were estimated for two sites that varied according to Annual Average Daily Traffic (AADT) density, fuel consumption, distance traveled by automobiles, and Mn concentration (mg l(-1)) in gasoline. Multiple regression analysis was used to predict the AADT volume from year 2002-2010. Comparison of the mass balance between the ANOVA means of 15% Mn emitted from the automobile tailpipes at 10, and 18 mg of Mn l(-1) in gasoline was conducted for both study sites. The percentage difference between the Mn input at the selected concentrations of Mn in gasoline and output into surface soil were found to be 99% significant for both sites. Thus the predicted 15% tailpipe emission levels for 10 mg of Mn l(-1) of gasoline used in automobiles, which represented 1290.03 g/year for site 1 and 555.94 g/year for site 2, will add 5.73 and 2.47 mg/kg of Mn annually, respectively. These input levels are considered negligible when compared to the natural abundance of Mn in soil. Based on these data, it could take more than 95-256 years of continuous MMT usage in the region to double the content of Mn in surface soils at the respective sites. PMID:15740767

  18. Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium

    NASA Astrophysics Data System (ADS)

    Parker, Dorothy L.; Sposito, Garrison; Tebo, Bradley M.

    2004-12-01

    The possible roles of siderophores (high affinity chelators of iron(III)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVD MnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVD MnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350-600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVD MnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A max = 408-410 nm) different from that of either PVD MnB1-Fe(III) or uncomplexed PVD MnB1. Mn(III) competed strongly with Fe(III) for binding by PVD MnB1 in culture filtrates (pH 8, 4°C). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVD MnB1 complex at a citrate/PVD MnB1 molar ratio of 830 (pH 8, 4°C), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVD MnB1 complex. Most of the PVD MnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVD MnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4°C) for the neutral species MnHPVD MnB1 (log K = 47.5 ± 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVD MnB1 (log K = 44.6 ± 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron.

  19. Potential of dandelion ( Taraxacum officinale) as a bioindicator of manganese arising from the use of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline

    Microsoft Academic Search

    L. Normandin; G. Kennedy; J. Zayed

    1999-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic manganese (Mn) compound currently added to unleaded gasoline in Canada. It has been suggested that the combustion of MMT containing Mn could cause various deleterious health effects in animals and humans at very high concentrations. This study evaluates the potential of dandelions (Taraxacum officinale) as bioindicators of Mn environmental comtamination. Samples were picked

  20. The Steel Band.

    ERIC Educational Resources Information Center

    Weil, Bruce

    1996-01-01

    Describes studying the steel drum, an import from Trinidad, as an instrument of intellectual growth. Describes how developing a steel drum band provided Montessori middle school students the opportunity to experience some important feelings necessary to emotional growth during this difficult age: competence, usefulness, independence, and…

  1. Aluminum Coatings for Steel

    Microsoft Academic Search

    Aruna Bahadur

    1996-01-01

    Aluminum coated steel possesses excellent oxidation and corrosion resistance in sulfur and marine: environments and can substitute for expensive alloy of steels. Hot dip aluminizing (HAD) and pack cementation calorizing (CAL) are dealt with in detail. IN HDA coats, some alloying action takes place, when the substrate is dipped in molten Al at 973 K for 1-2 minutes. The coat

  2. NIOBIUM IN RAIL STEEL

    Microsoft Academic Search

    Harald de Boer; Hiroki Masumoto

    The present paper reviews the key developments that have taken place in the production of niobium containing rail steels. An overall perspective is given on the fundamental metallurgical principals behind such steels together with the process developments that have taken place in Europe, the USA and Japan. A number of strategies are described for the production of as-rolled high strength

  3. Steel Industry Wastes.

    ERIC Educational Resources Information Center

    Schmidtke, N. W.; Averill, D. W.

    1978-01-01

    Presents a literature review of wastes from steel industry, covering publications of 1976-77. This review covers: (1) coke production; (2) iron and steel production; (3) rolling operations; and (4) surface treatment. A list of 133 references is also presented. (NM)

  4. Nanoscale surface analysis on second generation advanced high strength steel after hot dip galvanizing.

    PubMed

    Arndt, M; Duchoslav, J; Preis, K; Samek, L; Stifter, D

    2013-09-01

    Second generation advanced high strength steel is one promising material of choice for modern automotive structural parts because of its outstanding maximal elongation and tensile strength. Nonetheless there is still a lack of corrosion protection for this material due to the fact that cost efficient hot dip galvanizing cannot be applied. The reason for the insufficient coatability with zinc is found in the segregation of manganese to the surface during annealing and the formation of manganese oxides prior coating. This work analyses the structure and chemical composition of the surface oxides on so called nano-TWIP (twinning induced plasticity) steel on the nanoscopic scale after hot dip galvanizing in a simulator with employed analytical methods comprising scanning Auger electron spectroscopy (SAES), energy dispersive X-ray spectroscopy (EDX), and focused ion beam (FIB) for cross section preparation. By the combination of these methods, it was possible to obtain detailed chemical images serving a better understanding which processes exactly occur on the surface of this novel kind of steel and how to promote in the future for this material system galvanic protection. PMID:23404132

  5. Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide

    USGS Publications Warehouse

    Balistrieri, L.S.; Chao, T.T.

    1990-01-01

    This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.

  6. Manganese status of baby pigs born to sows on low or high manganese diets

    SciTech Connect

    Bell, L.; Christianson, S.; Peo, E. Kies, C. (Univ. of Nebraska, Lincoln (United States))

    1991-03-15

    The main route to manganese (Mn) excretion is in the bile, which normally begins within the first few days of life. The objective of the research was: to determine when Mn excretion commences; to determine the Mn content in liver, heart, kidney and brain of baby pigs born to sows on a high or low Mn diet; and compare these values with sow milk concentration. The Mn concentration in sow milk increases from day 1 to day 3 to day 7 and was consistently higher in the high Mn group vs the low Mn group. Initial excretions of Mn were high at birth and gradually decreased by day 4, then increased slightly on day 7. The Mn excretion values were also consistently higher in the high Mn group vs the low Mn group. There were no significant differences between Mn values in any of the organs from baby pigs in the low or high Mn groups. In both groups there was a significant increase in organ Mn concentration between day of birth and day 7. Thus, baby pigs consuming sow milk of high or low Mn concentrations accumulated the amount of Mn needed for growth and tended to excrete any excess.

  7. Radiocarbon dating of magnetic and non magnetic soil fractions as a method to estimate the heterotrophic component of soil respiration in a primary forest of Ghana.

    NASA Astrophysics Data System (ADS)

    Chiti, T.; Certini, G.; Marzaioli, F.; Valentini, R.

    2012-04-01

    We estimated the heterotrophic component (Rh) of soil respiration in a primary forest of Ghana by radiocarbon dating, a method we already successfully applied in temperate and Mediterranean forests. In this case, given the advanced stage of alteration of tropical soils, which are thus rich in oxides, we implemented the method on soil fractions obtained by High Gradient Magnetic Separation (HGMS), hence based on different degrees of magnetic susceptibility. In particular, we separated an organic pool associated with magnetic minerals (e.g iron oxides) from an organic pool engaged with non-magnetic minerals. This non destructive method of fractionation, often applied to the finest fraction of soil (clay), is here attempted on the bulk fine earth (< 2 mm). We sampled the soil at 0-5, 5-15, 15-10, and 30-50 cm depth intervals, since a previous study in the same site suggested that only the first 50 cm of soil was enriched in bomb carbon (C younger than 1950). The samples of each layer were sieved at 2 mm and further at 0.5 mm ,so as to have two size fractions: 2 to 0.5 mm and <0.5 mm, and both of them were separated into a magnetic and non magnetic fraction. All the specimens were then investigated in terms of mineralogical assemblage (by X-Ray diffrattometry), chemical structure of the organic component (13C NMR spectroscopy), and 14C concentration (AMS) for inferring the mean residence time (MRT) of the organic component in the soil. Radiocarbon concentration was always higher in the finest SOC fractions (<0.5 mm), with the magnetic fraction always showing an higher 14C concentration than the non magnetic one. The magnetic and non magnetic materials of the coarser fraction (0.5-2 mm) showed quite similar 14C concentrations in all of the soil layers investigated. The composition of the organic matter is different in the different fractions and partly explains the differences in MRT, although a major role in preserving the organics from decomposition is probably played by the physical protection in aggregates. Surprisingly, the non magnetic fraction is not influenced at all by the bomb C (negative delta 14) already at a depth of 5-15 cm and, even, at 15-30 cm all the four fractions have pre-bomb C, which means relatively high radiocarbon age. The finest fractions are the main contributors to the Rh flux, particularly the magnetic fraction (<0-5 mm) which show also the higher C concentration among all fractions, opposite to the non-magnetic one that is poorer in C. The Rh flux, estimated from the mean residence time of the fractions and their C amount, allowed to get a more precise estimate with respect to a previous one performed at the same site with radiocarbon analyses on bulk soils. The Rh flux from soil is hard to be estimate based on radiocarbon analysis of the bulk soil alone, and only by means of a SOC fractionation the Rh flux can be estimated quite accurately. This alternative approach for estimating the Rh component of CO2 from soils of tropical areas is currently being applied in 10 tropical forest sites in western and central Africa in the context of the ERC Africa GHG project, and together with measurements of the C inputs annually entering the soil will allow determining the sink-source capacity of primary forest soils.

  8. Effect of Inclusions' Behavior on the Microstructure in Al-Ti Deoxidized and Magnesium-Treated Steel with Different Aluminum Contents

    NASA Astrophysics Data System (ADS)

    Wu, Zhenhua; Zheng, Wan; Li, Guangqiang; Matsuura, Hiroyuki; Tsukihashi, Fumitaka

    2015-02-01

    To clarify the precipitation behavior of beneficial inclusions and mechanism of their effects on microstructure, the effect of aluminum content on inclusion's characteristics and their influence on the refinement of microstructure in Al-Ti complex deoxidized magnesium-treated steels were systematically investigated based on experiment and calculation. The results showed that due to the dual effects of Ti and Mg deoxidation, a large amount of finely dispersed Al2O3-TiO x -MgO inclusions in low aluminum steel with a complex multilayer or mosaic structure were formed, whereas a relatively smaller amount of Al2O3-MgO inclusions with the simple bundle structure were observed in high aluminum steel. The Al2O3-TiO x -MgO core oxides are more conducive to the precipitation of multiple manganese sulfides with thinner thickness on their local surfaces. Thus, the inclusion deformation, which mainly depends on the surface manganese sulfides layer, is smaller in low aluminum steel than that in high aluminum steel. Complex inclusions in low aluminum steel can pin austenite grain boundaries and induce interlocking acicular ferrite effectively. In addition to the small size and chemical composition of inclusions, the complex structure of oxides and the precipitation of multiple MnS on their surface are important to the nucleation of interlocking AFs on inclusions in Ti-deoxidized Mg-treated steel. The AFs quantity is much more, and the grain size is more uniform in low aluminum steel than that in high aluminum steel.

  9. Oxidative decolorization of direct light red F3B dye at natural manganese mineral surface

    Microsoft Academic Search

    Ruixia Liu; Hongxiao Tang

    2000-01-01

    In this paper, the characteristics of natural manganese mineral collected from Guangxi Province, China, including crystalline properties, elemental composition, organic substrates content (0.17%) and BET surface area (29.8 m2\\/g), were determined. By X-ray powder diffraction and fluorescence spectrograph analysis, it is shown that manganese oxide in the natural mineral exists in the crystal structure of ?-Mn2O3 and the contents of manganese

  10. Pharmacokinetics of Inhaled Manganese Phosphate in Male Sprague–Dawley Rats Following Subacute (14Day) Exposure

    Microsoft Academic Search

    Domenico Vitarella; Brian A. Wong; Owen R. Moss; David C. Dorman

    2000-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as a gasoline octane enhancer. Manganese phosphate is the primary respirable (PM2.5) MMT-combustion product emitted from the automobile tailpipe. The goal of this study was to determine the exposure–response relationship for inhaled manganese phosphate in adult male CD rats. Rats were exposed 6-h\\/day for either 5 days\\/week (10 exposures) or 7 days\\/week (14 exposures)

  11. Manganese ?2-complexes as auxiliaries for stereoselective aldol synthesis of allenyl carbinols.

    PubMed

    Bhowmick, Manishabrata; Lepore, Salvatore D

    2010-11-01

    A convenient and robust manganese auxiliary was linked via an ?(2)-bond to alkynyl esters and ketones using a mild complexation reaction with methylcyclopentadienyl manganese tricarbonyl. This complex readily underwent aldol reactions with exclusive ?-substitution and in good diastereoselectivities especially with aryl ketone substrates. This selectivity has been rationalized using a cyclic transition state model in which the manganese auxiliary plays a critical role in promoting E(O)-geometry of the cumulenolate intermediate. PMID:20936852

  12. Determination of (methylcyclopentadienyl)manganese tricarbonyl in gasolines by gas chromatography with flame photometric detection

    Microsoft Academic Search

    Walter A. Aue; Brian. Millier; Xun Yun. Sun

    1990-01-01

    The common gasoline additive (methylcyclopentadienyl)manganese tricarbonyl (MMT) can be determined down to 0.6 ppm (w\\/w) levels in gasoline, by using atomic emission from a simple, inexpensive, and commercially available flame photometric detector. Other manganese compounds respond to similar to MMT. Quenching caused by the carbon background is insignificant. The chemiluminescence from manganese compares favorably with signals from compounds of sulfur,

  13. Oxidation of chalcopyrite in the presence of manganese dioxide in hydrochloric acid medium

    Microsoft Academic Search

    N. B Devi; M Madhuchhanda; K. Srinivasa Rao; P. C Rath; R. K Paramguru

    2000-01-01

    Dissolution of chalcopyrite in hydrochloric acid medium in the presence of manganese dioxide (manganese ore containing pyrolusite) was studied at different temperatures, acid concentrations and mineral proportions. Chalcopyrite did not dissolve independently, but underwent oxidative dissolution in the presence of manganese dioxide, via (i) galvanic interaction, (ii) cyclic action of Fe3+\\/Fe2+ redox couple and (iii) chlorine gas generated by MnO2

  14. A search for luminescence of the trivalent manganese ion in solid aluminates

    Microsoft Academic Search

    A VANDIE; A LEENAERS; W VANDERWEG; G BLASSE

    1987-01-01

    As an alternative way of examining the prospects of the trivalent manganese ion as a luminescent centre in glasses, AI203:Mn , ZnAI204:Mn and LaAIO3:Mn were investigated by means of spectrofluorometry. The luminescent species identified were divalent and tetravalent manganese and impurities (chromium), whereas trivalent manganese did not show luminescence at wavelengths ~ 800 nm in LaAIO3:Mn and ZnAI204:Mn and i000

  15. Manganese, copper, and zinc in cerebrospinal fluid from patients with multiple sclerosis

    Microsoft Academic Search

    Torun M. Melø; Cecilie Larsen; Linda R. White; Jan Aasly; Torill E. Sjøbakk; Trond P. Flaten; Ursula Sonnewald; Tore Syversen

    2003-01-01

    The concentrations of manganese, copper, and zinc in cerebrospinal fluid (CSF) from patients with multiple sclerosis (MS)\\u000a and patients with no known neurological disease (control group) were measured. Manganese and copper levels were determined\\u000a by two different analytical methods: atomic absorption spectrometry (AAS) and high-resolution inductively coupled plasma-mass\\u000a spectrometry (HR-ICP-MS), whereas zinc levels were determined by HR-ICP-MS only. Manganese levels

  16. Migration of Mn cations in delithiated lithium manganese oxides.

    PubMed

    Kan, Yongchun; Hu, Yuan; Lin, Chi-Kai; Ren, Yang; Sun, Yang-Kook; Amine, Khalil; Chen, Zonghai

    2014-10-14

    Li2MnO3 is an integrated component in lithium-manganese-rich nickel manganese cobalt oxides, and the conversion of Li2MnO3 to a spinel-like structure after electrochemical activation has been associated with the continuous potential decay of the material. Delithiated Li2MnO3 and delithiated LiMn2O4 were used as model materials to investigate the mechanism of forming the spinel-like structure. An in situ high-energy X-ray diffraction technique was used to trace the structural change of materials at elevated temperatures, a procedure to mimic the structural transformation during the normal cycling of batteries. It was also found that the migration of Mn atoms from the octahedral sites to tetrahedral sites is the key step for phase transformation from a monoclinic structure to a spinel structure. PMID:25162360

  17. Manganese oxide nanowires, films, and membranes and methods of making

    DOEpatents

    Suib, Steven Lawrence (Storrs, CT); Yuan, Jikang (Storrs, CT)

    2008-10-21

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

  18. Preliminary LIBS analysis of Yucca Mountain manganese oxide minerals

    SciTech Connect

    Blacic, J.; Pettit, D.; Cremers, D.

    1996-01-01

    The licensing and performance of a potential repository at Yucca Mountain will require the characterization of radionuclide sorptive capacity of the host rock, which in turn calls for hundreds of analyses based on extensive sampling or in situ measurements. A rapid method specifically for characterizing the manganese oxide minerals occurring heterogeneously throughout the Yucca Mountain block as fracture surface coatings is needed. Our unique solution is a laser-induced breakdown spectroscopy (LIBS) surface-analysis technique that is usable in the field to produce high-resolution atomic emission spectra. In tests with manganese oxide minerals and fracture surface coatings from a few Yucca Mountain core samples, we used four spectral bands to show that qualitative measurement of all constituent elements except K and Na (in the presence of Mn) is possible with LIBS. Detailed calibration of final hardware will make the system quantitative.

  19. Manganese in gasoline. Council on Scientific Affairs, American Medical Association.

    PubMed

    Lyznicki, J M; Karlan, M S; Khan, M K

    1999-03-01

    This report responds to a resolution that asked the American Medical Association (AMA) to take action to reduce potential health risks from the use of methylcyclopentadienyl manganese tricarbonyl (MMT) in gasoline. Information for this report was derived from a search of the MEDLINE database and references listed in pertinent articles, as well as through communications with medical and public health experts. Based on this information, the AMA Council on Scientific Affairs determined that there is insufficient scientific evidence to assess the public health impact of MMT use. While limited evidence indicates that general-population exposures to manganese from the use of MMT in gasoline are low, more research is needed to determine possible health effects from long-term, low-dose exposures to MMT and its combustion products. Until such data are available, educational and informational strategies should be developed to improve public awareness of the health and environmental issues surrounding MMT use. PMID:10091136

  20. Magnetic Susceptibility Measurements of Solid Manganese Compounds with Evan's Balance

    NASA Astrophysics Data System (ADS)

    Teweldemedhin, Z. S.; Fuller, R. L.; Greenblatt, M.

    1996-09-01

    An experiment on the determination of the magnetic susceptibility of several solid manganese compounds including KMnO4, MnO, MnTiO3, alpha-Mn2O3 and MnO2 with a simple, commercially available magnetic susceptibility balance (Johnson matthey) is described. The experiment is appropriate for a junior/senior level undergraduate inorganic or physical chemistry laboratory. The fundamental principles of magnetism and magnetic interactions in solids are introduced. The study of the magnetic susceptibility of the series of manganese oxides, with different formal oxidations states of the Mn ions in each, illustrates how the number of unpaired electrons and evidence of magnetic interactions may be determined from the magnetic data.

  1. Applications of Manganese-Enhanced Magnetic Resonance Imaging in Neuroscience

    NASA Astrophysics Data System (ADS)

    McCreary, J. Keiko

    Manganese-Enhanced Magnetic Resonance Imaging (MEMRI) has proven itself to be a beneficial technique in the field of Neuroscience. This thesis applies MEMRI to studies in neuroscience by first establishing the limitations concerning the use of MEMRI in live rats. Experiment 1 used an osmotic pump for manganese (Mn) delivery to the lateral ventricles for acquisition of anatomical images using MEMRI. From my knowledge, this was the first method demonstrating slow infusion of Mn to the lateral ventricles. In Experiment 2, MEMRI was used for volumetric analysis the whole brain and hippocampus of prenatally stressed rats. To my knowledge, this study was the first to investigate the effect of generational prenatal stress on the structure of a rat's brain using MEMRI and histology. Additionally, Experiment 2 investigated the use of a subcutaneous osmotic pump to deliver Mn for MEMRI. A summary on the use of MEMRI in Neuroscience concludes this thesis, with a discussion on the methods used and related technical considerations.

  2. Nanostructured cobalt manganese ferrite thin films for gas sensor application

    Microsoft Academic Search

    Izabela Sandu; Lionel Presmanes; Pierre Alphonse; Philippe Tailhades

    2006-01-01

    Ferrite compounds are very important because of their optical, electrical or magnetic properties. Moreover, many papers relate to their development as possible gas sensor.In this study, we were interested in using cobalt–manganese–ferrite as sensitive layer for CO2 sensor devices. Such an application required a high surface activity, and consequently a small crystallite size and a large surface area. The physical

  3. Biogenic manganese oxides: Properties and mechanisms of formation

    Microsoft Academic Search

    Bradley M. Tebo; Bradley M; Brian G. Clement; Gregory J. Dick; Karen J. Murray; Dorothy Parker; Rebecca Verity; Samuel M. Webb

    2004-01-01

    ? Abstract Manganese(IV) oxides produced through microbial activity, i.e., bio- genic Mn oxides or Mn biooxides, are believed to be the most abundant and highly reactive Mn oxide phases in the environment. They mediate,redox reactions with or- ganic and inorganic compounds,and sequester a variety of metals. The major pathway for bacterial Mn(II) oxidation is enzymatic, and although bacteria that oxidize

  4. Manganese?Release Characteristics of Highly Calcareous Soils

    Microsoft Academic Search

    M. Maftoun; V. Olama; B. Molazem; M. Tavajjoh

    2009-01-01

    Manganese (Mn) deficiency is common in calcareous soils of southern Iran. The ability of these soils to replenish the soil solution Mn depends highly on their Mn?release characteristics. Kinetics of native Mn release by ammonium bicarbonate diethylenetriaminepentaacetic acid (AB?DTPA) from 10 highly calcareous soils were studied for the periods of 1 to 1440 min. Results showed that Mn?release rates were initially

  5. Manganese deposits on Mars suggest a highly oxidized past

    NASA Astrophysics Data System (ADS)

    Rosen, Julia

    2014-11-01

    As the Curiosity rover picks its way across the Martian surface, sampling rocks and snapping photos, it searches for signs that the dusty craters and ridges under its treads may once have supported life or, at least, that they might have been habitable. Now, using measurements of manganese abundances in Martian rocks, Lanza et al. provide new evidence that Mars may have hosted liquid water and a more strongly oxygenated atmosphere at some point in its past.

  6. Environmental and occupational exposure to manganese: a multimedia assessment

    Microsoft Academic Search

    Sylvain Loranger; Joseph Zayed

    1995-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic additive used in Canada since 1976 as an anti-knock agent in unleaded gasoline. Its combustion leads to the emission of Mn oxides, especially Mn3O4. Since no study has assessed the potential risk of chronic exposure to low concentrations resulting from these emissions, the present investigation was undertaken to assess the level of environmental

  7. Microwave Resonance and Relaxation of Excess-Iron Manganese Ferrites

    Microsoft Academic Search

    Yoshiyuki Watanabe

    1973-01-01

    FMR measurements at 9.3 GHz have been made on single crystal disks of manganese ferrites with resistivities of the order of 0.1 \\\\varOmegacm (300 K), for various values of thickness. Comparison of the data with calculated absorption formulae indicates that an appreciable influence of skin depth effect remains until the thickness becomes as small as about 40 mum. This means

  8. Low-Temperature Specific Heat Anomaly in Manganese Ferrites

    Microsoft Academic Search

    Brooks Low

    1963-01-01

    The specific heats of a series of ferrites Mnx FeyO4 with x+y≈3, have been measured in the range 1.5°K to 6°K. The specific heats are anomalously large in this temperature range, and the anomaly increases with increasing manganese concentration. If the relatively small estimated lattice contribution is subtracted out, the resulting Cv vs T curves are concave downward, suggesting a

  9. Toxicity of manganese to Ceriodaphnia dubia and Hyalella azteca

    USGS Publications Warehouse

    Lasier, P.J.; Winger, P.V.; Bogenrieder, K.J.

    2000-01-01

    Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments and pore waters. Manganese can be present at toxic levels in anoxic solutions due to its increased solubility under chemically-reducing conditions, and it can remain at those levels for days in aerated test waters due to slow precipitation kinetics. Ceriodaphnia dubia and Hyalella azteca are freshwater organisms often used for toxicity testing and recommended for assessments of effluents and pore waters. Lethal and reproductive-inhibition concentrations of Mn were determined for C. dubia in acute 48h tests and chronic 3-brood tests using animals <24 h old and between 24 and 48 h old. Sensitivity of H. azteca was determined with 7d old animals in acute 96h tests. Tests were run at three levels of water hardness to assess the amelioratory effect, which was often significant. Manganese concentrations were measured analytically at test initiation and after 96 h for calculations of toxicity endpoints and determinations of Mn precipitation during the tests. Minimal amounts of Mn (below 3%) precipitated within 96 h. LC50s determined for H. azteca progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately-hard and hard waters, respectively. The tolerance of C. dubia to Mn was not significantly different between moderately-hard and hard waters, but was significantly lower in soft water. There was no significant difference in Mn sensitivity between the ages of C. dubia tested. Acute LC50 values for C. dubia averaged 6.2, 14.5 and 15.2 mg Mn/L and chronic IC50 values averaged 3.9, 8.5 and 11.5 mg Mn/L for soft, moderately-hard and hard waters, respectively. Manganese toxicity should be considered when assessing solutions with concentrations near these levels.

  10. Hydrogen Bonding in Human Manganese Superoxide Dismutase Containing 3-Fluorotyrosine

    Microsoft Academic Search

    Idelisa Ayala; J. Jefferson P. Perry; Jan Szczepanski; John A. Tainer; Martin T. Vala; Harry S. Nick; David N. Silverman

    2005-01-01

    Incorporation of 3-fluorotyrosine and site-specific mutagenesis has been utilized with Fourier transform infrared (FTIR) spectroscopy and x-ray crystallography to elucidate active-site structure and the role of an active-site residue Tyr34 in human manganese superoxide dismutase (MnSOD). Calculated harmonic frequencies at the B3LYP\\/6-31G** level of theory for L-tyrosine and its 3-fluorine substituted analog are compared to experimental frequencies for vibrational mode

  11. Manganese Transport in the Neural Circuit of Rat CNS

    Microsoft Academic Search

    Atsushi Takeda; Yuka Kodama; Shioji Ishiwatari; Shoji Okada

    1998-01-01

    To study manganese (Mn) transport in the neural circuit of rat CNS, brain isotope distribution after 54Mn injection into the brain was analyzed by autoradiography. One day after 54MnCl2 injection into the striatum, 54Mn was highly distributed in the ipsilateral thalamus, hypothalamus, and substantia nigra. When 54MnCl2 was bilaterally injected into the striata after unilateral treatment with colchicine or vehicle

  12. Environmental Factors Affecting Oxidation of Manganese in Pinal Creek, Arizona

    Microsoft Academic Search

    Justin C. Marble; Timothy L. Corley; Martha H. Conklin; Christopher C. Fuller

    The objectives of the laboratory work reported here were to quantify the net rates of removal of manganese (Mn(II)) by streambed sediments collected from a metals contaminated, perennial stream system (Pinal Creek near Globe AZ) and to determine the key variable(s) responsible for the limited removal of Mn(II) observed at this field site. Pinal Creek is characterized by significant spatial

  13. The fracture toughness of a ferrous maraging alloy containing manganese

    Microsoft Academic Search

    Raymond Brook; Christopher Musiol

    1976-01-01

    A Fe-20 pct Co-15 pct Mn-5 pct Mo maraging alloy has been found to exhibit low toughness and brittle fracture throughout its\\u000a response to age-hardening. Intergranular embrittlement associated with segregation of manganese and with residual oxygen (15\\u000a to 300 ppm) in the early stages of aging was replaced by brittle inter-lath separation as aging progressed, the latter mode\\u000a being associated

  14. The fracture toughness of a ferrous maraging alloy containing manganese

    Microsoft Academic Search

    Raymond Brook; Christopher Musiol

    1976-01-01

    A Fe-20 pet Co-15 pet Mn-5 pet Mo maraging alloy has been found to exhibit low toughness and brittle fracture throughout its\\u000a response to age-hardening. Inter granular embrittlement associated with segregation of manganese and with residual oxygen\\u000a (15 to 300 ppm) in the early stages of aging was replaced by brittle inter-lath separation as aging progressed, the latter\\u000a mode being

  15. Spin-Polarization Dependent Small Polaron Hopping in Manganese Perovskites

    Microsoft Academic Search

    Ning Zhang

    2003-01-01

    A model of small polaron hopping being dependent on spin-polarization is suggested to describe the transport and the colossal magnetoresistance behaviors in manganese perovskites R-A-Mn-O (R: rear earth; A: alkali earth or transition metals). Being different from the theory of simple small polarons, the double exchange interaction and some empirical rules related to lattice effect induced by an external magnetic

  16. Prenatal manganese levels linked to childhood behavioral disinhibition

    Microsoft Academic Search

    Jonathon E. Ericson; Francis M. Crinella; K. Alison Clarke-Stewart; Virginia D. Allhusen; Tony Chan; Richard T. Robertson

    2007-01-01

    Although manganese (Mn) is an essential mineral, high concentrations of the metal can result in a neurotoxic syndrome affecting dopamine balance and behavior control. We report an exploratory study showing an association between Mn deposits in tooth enamel, dating to the 20th and 62–64th gestational weeks, and childhood behavioral outcomes. In a sample of 27 children, 20th week Mn level

  17. Role of the manganese efflux system mntE for signalling and pathogenesis in Streptococcus pneumoniae

    PubMed Central

    Rosch, Jason W.; Gao, Geli; Ridout, Granger; Wang, Yong-Dong; Tuomanen, Elaine I.

    2009-01-01

    Summary The ability of bacteria to sense and respond to both environmental and intracellular metal concentrations plays an important role in pathogenesis. The acquisition of manganese is vital for the virulence of several bacterial species. Although manganese uptake systems have been well studied in bacteria, no manganese efflux system has yet been identified. In this study we have identified a cation diffusion facilitator (CDF) protein (Sp1552) of unknown substrate specificity that functions as a manganese export system in Streptococcus pneumoniae. We designated the gene for this manganese efflux system mntE and found that the mutant strain was highly sensitive to manganese stress. Although the mutant was more resistant to oxidative stress and produced more H2O2 and pili, it had reduced virulence in a murine model of infection, indicating that manganese export plays a role in host pathogenesis. There was a distinct differential transcriptional response to extracellular and intracellular manganese accumulation. Our study indicates that manganese efflux is required for invasive disease and may provide a useful antimicrobial target to devise future therapeutics. PMID:19226324

  18. The INAA determination of environmental manganese from the gasoline additive MMT

    SciTech Connect

    Kennedy, G.; Zayed, J. [Univ. of Montreal (Canada)

    1996-12-31

    Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used as an antiknock agent in gasoline in Canada since 1976, and it has now been approved for use in the United States and other countries. It has been suggested that health risks due to manganese emissions from automobiles should be much lower than those due to lead- and organic-based additives, which MMT replaces. This is being verified by an extensive research program at the University of Montreal, where manganese has been determined in all environmental compartments that may contribute to human exposure. Instrumental neutron activation analysis (INAA) was found to be the ideal method for manganese determination in all the environmental materials studied.

  19. Manganese neurotoxicity: behavioral, pathological, and biochemical effects following various routes of exposure.

    PubMed

    Normandin, Louise; Panisset, Michel; Zayed, Joseph

    2002-01-01

    The human central nervous system is an important target for manganese intoxication, which causes neurological symptoms similar to those of Parkinson's disease. With the increasing use of methylcyclopentadienyl manganese tricarbonyl (MMT) as an octane-improving additive to unleaded gasoline, the prospect of worldwide manganese exposure is once again attracting attention as increases in environmental manganese concentrations have been recorded relative to traffic density. One crucial question is whether a small increase of manganese contamination resulting from the widespread use of MMT could have neurotoxic effects. In this review we concentrate on central nervous system abnormalities and neurobehavioral disturbances. Most experimental animal studies on manganese neurotoxicity have been conducted in nonhuman primates and rodents. Most studies performed in rodents used oral manganese administration and did not assess bioaccumulation or central nervous system changes. The major effect found was transient modification of spontaneous motor activity. Very few inhalation toxicological studies were carried out. As manganese intoxication in humans usually occurs via inhalation, more studies are required using the respiratory route of administration. Given the proven neurotoxic effects of manganese and the prospect of worldwide MMT usage, this metal should be considered a new environmental pollutant having potentially widespread public health consequences. PMID:12462483

  20. Effects of Chronic Manganese Exposure on Cognitive and Motor Functioning in Non-Human Primates

    PubMed Central

    Schneider, Jay S.; Decamp, Emmanuel; Koser, Amy Jo; Fritz, Stephanie; Gonczi, Heather; Syversen, Tore; Guilarte, Tomás R.

    2007-01-01

    Acute exposure to manganese is associated with complex behavioral/psychiatric signs that may include Parkinsonian motor features. However, little is known about the behavioral consequences of chronic manganese exposures. In this study, cynomolgus macaque monkeys were exposed to manganese sulfate (10 –15 mg/kg/week) over an exposure period lasting 272 ± 17 days. Prior to manganese exposure, animals were trained to perform tests of cognitive and motor functioning and overall behavior was assessed by ratings and by videotaped analyses. By the end of the manganese exposure period, animals developed subtle deficits in spatial working memory and had modest decreases in spontaneous activity and manual dexterity. In addition, stereotypic or compulsive-like behaviors such as compulsive grooming increased in frequency by the end of the manganese exposure period. Blood manganese levels measured at the end of the manganese exposure period ranged from 29.4 to 73.7 ?g/L (mean = 55.7 ± 10.8 (compared to levels of 5.1–14.2 ?g/L at baseline (mean = 9.2 ± 2.7), placing them within the upper range of levels reported for human environmental, medical or occupational exposures. These results suggest that chronic exposure to levels of manganese achieved in this study may have detrimental effects on behavior, cognition and motor functioning. PMID:16978592

  1. 40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...424.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERROALLOY MANUFACTURING POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 Applicability;...

  2. Effect of manganese deficiency on wound healing glycosaminoglycans

    SciTech Connect

    Shetlar, M.R.; Shetlar, C.L. (Texas Tech Univ., Lubbock (United States))

    1991-03-15

    Manganese deficiency has been shown to depress proteglycan biosynthesis in the bone matrix in several species. Since the process of wound healing involves increased glycosaminoglycan (GAG) biosynthesis, the authors have made studies of the biosynthesis of GAGS in a wound healing model used in rats fed a diet deficient in manganese. Twelve female albino rats, 22-25 days old were divided into two groups of 6 each. One group was fed the manganese deficient diet; the second group was fed Purina Rodent diet. At maturation these females were mated with males on the Purina diet. Females were maintained on the same respective diets during gestation, delivery and lactation. From the offspring at weaning time, 12 males and 12 females were selected from each diet group. These animals were continued on the respective diets of their dams for 120 days. Each animals was then implanted with an acrylic wound healing cylinder. After 14 days each was injected with 20 microcuies of 1-{sup 14}C-glucosamine. After 24 hours, the cylinders were removed and tissue stripped from the inside of the cylinders. GAGS were separated by cellulose acetate electrophoresis and the radioactivity associated with each fraction determined. Weights of the tissue from the deficient group were significantly decreased. Chondroitin-4-sulfate and the radioactivity associated with this fraction were also decreased in the deficient group.

  3. A redox-assisted supramolecular assembly of manganese oxide nanotube

    SciTech Connect

    Tao Li [College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory of Chemometrics and Chemical Biological Sensing Technologies, Ministry of Education, Changsha 410082 (China); Sun Chenggao [College of Chemistry and Chemical Engineering, Hunan University and Key Laboratory of Chemometrics and Chemical Biological Sensing Technologies, Ministry of Education, Changsha 410082 (China); Fan Meilian [College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory of Chemometrics and Chemical Biological Sensing Technologies, Ministry of Education, Changsha 410082 (China); Huang Caijuan [College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory of Chemometrics and Chemical Biological Sensing Technologies, Ministry of Education, Changsha 410082 (China); Wu Hailong [College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory of Chemometrics and Chemical Biological Sensing Technologies, Ministry of Education, Changsha 410082 (China); Chao Zisheng [College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory of Chemometrics and Chemical Biological Sensing Technologies, Ministry of Education, Changsha 410082 (China)]. E-mail: zschao@yahoo.com; Zhai Hesheng [College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)]. E-mail: hszhai@xmu.edu.cn

    2006-11-09

    In this paper, we report the hydrothermal synthesis of manganese oxide nanotube from an aqueous medium of pH 7, using KMnO{sub 4} and MnCl{sub 2} as inorganic precursors, polyoxyethylene (10) nonyl phenyl ether (TX-10) a surfactant and acetaldehyde an additive. The characterization of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and N{sub 2} adsorption at 77 K (BET) reveals that the synthesized manganese oxide nanotube has a mesopore size of ca. 3.65 nm and a wall thickness of ca. 12 nm, with the wall being composed of microporous crystals of monoclinic manganite. The X-ray photoelectron spectroscopy (XPS) result demonstrates a decrease of the binding energy of the Mn{sup 3+} in the manganese oxide nanotube, which may be related to both the nanotubular morphology and the crystalline pore wall. A mechanism of a redox-assisted supramolecular assembly, regulated by acetaldehyde, is postulated.

  4. Preliminary assessment of atmospheric methylcyclopentadienyl manganese tricarbonyl and particulate manganese in selected urban sites.

    PubMed

    Thibault, Christiane; Kennedy, Greg; Gareau, Lise; Zayed, Joseph

    2002-04-12

    Methylcyclopentadienyl manganese tricarbonyl (MMT: C9H7MnO3) is an organometallic additive that has been used since 1976 as an octane enhancer in Canadian unleaded gasoline. Very few studies have determined its atmospheric concentrations and only one study offers recent data on its ambient level. This preliminary study aims to assess atmospheric concentrations of MMT and respirable and total Mn (Mn(R) and Mn(T) in selected sites, at two underground car parks and one gasoline station, related to high levels of automobile traffic. It is also an investigation of the applicability of the current analytical method. In total, 34 air samples were collected using a Gil-Air portable pump during 4 consecutive days and then were analyzed by neutron activation analysis. The concentrations vary between 40 and 104 ng/m3 for Mn(R), 146 and 204 ng/m3 for Mn(T) and 6 and 128 ng/m3 for MMT (including ultrafine particulates, Mn(UF). Of the 12 Mn(R) results, 7 showed concentrations greater than the U.S. EPA reference concentration (RfC = 50 ng/m3). The ratios of Mn(R) to Mn(T) varied from 0.20 to 0.65 with a mean of 0.38. The results for MMT and Mn(UF) raise serious doubts about the specificity of the sampling and chemical analysis methodology proposed by the Occupational Safety and Health Administration (OSHA) for MMT in air. PMID:11939708

  5. Laser-induced fluorescence diagnostics of a propane\\/air flame with a manganese fuel additive. [methylcyclopentadienyl manganese tricarbonyl

    Microsoft Academic Search

    U. Westblom; F. Fernandez-Alonso; C. R. Mahon; G. P. Smith; J. B. Jeffries; D. R. Crosley

    1994-01-01

    Laser-induced fluorescence (LIF) has been used to investigate the effects of MMT, a manganese-containing fuel additive, on a premixed propane\\/air flame burning at 40 torr. The emphasis was placed on the chemistry of formation of prompt nitric oxide. No measurable effect due to the MMT on the gas-phase chemistry of this flame was observed. LIF profiles as a function of

  6. Manganese and iron both influence the shoot transcriptome of Typha angustifolia despite distinct preference towards manganese accumulation

    Microsoft Academic Search

    D. Chakraborty; S. Abhay Kumar; M. Sen; S. K. Apte; S. Das; R. Acharya; T. Das; A. V. R. Reddy; S. Roychaudhury; H. Rajaram; A. Seal

    2011-01-01

    Typha angustifolia is a metal hypertolerant grass that predominates the wetlands of uranium tailings in Jaduguda, India, contaminated with extreme\\u000a levels of iron (Fe) and manganese (Mn). In the paper investigations were carried out to understand the molecular mechanism\\u000a of metal tolerance in this tolerant macrophyte. Metal analysis was coupled with fluorescent differential display (FDD) and\\u000a reverse northern to compare

  7. The effect of manganese supply on thyroid hormone metabolism in the offspring of manganese-depleted dams

    Microsoft Academic Search

    Klaus Eder; Angelika Kralik; Manfred Kirchgessner

    1996-01-01

    The present study was performed to investigate the effect of manganese (Mn) supply on metabolism of thyroid hormones in the\\u000a rat. A study with rats was carried out over two generations. Female rats were raised with a Mn-deficient diet (0.1 mg Mn\\/kg),\\u000a and mated to produce a second generation. The male rats of the second generation were used as subjects

  8. Manganese distribution in the brain and neurobehavioral changes following inhalation exposure of rats to three chemical forms of manganese.

    PubMed

    Normandin, Louise; Ann Beaupré, Linda; Salehi, Fariba; St -Pierre, Annie; Kennedy, Greg; Mergler, Donna; Butterworth, Roger F; Philippe, Suzanne; Zayed, Joseph

    2004-03-01

    The central nervous system is an important target for manganese (Mn) intoxication in humans; it may cause neurological symptoms similar to Parkinson's disease. Manganese compounds emitted from the tailpipe of vehicles using methylcyclopentadienyl manganese tricarbonyl (MMT) are primarily Mn phosphate, Mn sulfate, and Mn phosphate/sulfate mixture. The purpose of this study is to compare the patterns of Mn distribution in various brain regions (olfactory bulb, frontal parietal cortex, globus pallidus, striatum and cerebellum) and other tissues (lung, liver, kidney, testis) and the neurobehavioral damage following inhalation exposure of rats to three Mn species. Rats (n=15 rats per Mn species) were exposed 6 h per day, 5 days per week for 13 consecutive weeks to metallic Mn, Mn phosphate or Mn phosphate/sulfate mixture at about 3000 microgm(-3) and compared to controls. At the end of the exposure period, spontaneous motor activity was measured for 36 h using a computerized autotrack system. Mn in tissues was determined by instrumental neutron activation analysis (INAA). The Mn concentrations in the brain were significantly higher in rats exposed to Mn phosphate and Mn phosphate/sulfate mixture than in control rats or rats exposed to metallic Mn. Exposure to Mn phosphate/sulfate mixture caused a decrease in the total ambulatory count related to locomotor activity. Our results confirm that Mn species and solubility have an influence on the brain distribution of Mn in rats. PMID:15019306

  9. Manganese oxide nanosheets and a 2D hybrid of graphene–manganese oxide nanosheets synthesized by liquid-phase exfoliation

    NASA Astrophysics Data System (ADS)

    Coelho, João; Mendoza-Sánchez, Beatriz; Pettersson, Henrik; Pokle, Anuj; McGuire, Eva K.; Long, Edmund; McKeon, Lorcan; Bell, Alan P.; Nicolosi, Valeria

    2015-06-01

    Manganese oxide nanosheets were synthesized using liquid-phase exfoliation that achieved suspensions in isopropanol (IPA) with concentrations of up to 0.45 mg ml?1. A study of solubility parameters showed that the exfoliation was optimum in N,N-dimethylformamide followed by IPA and diethylene glycol. IPA was the solvent of choice due to its environmentally friendly nature and ease of use for further processing. For the first time, a hybrid of graphene and manganese oxide nanosheets was synthesized using a single-step co-exfoliation process. The two-dimensional (2D) hybrid was synthesized in IPA suspensions with concentrations of up to 0.5 mg ml?1 and demonstrated stability against re-aggregation for up to six months. The co-exfoliation was found to be a energetically favorable process in which both solutes, graphene and manganese oxide nanosheets, exfoliate with an improved yield as compared to the single-solute exfoliation procedure. This work demonstrates the remarkable versatility of liquid-phase exfoliation with respect to the synthesis of hybrids with tailored properties, and it provides proof-of-concept ground work for further future investigation and exploitation of hybrids made of two or more 2D nanomaterials that have key complementary properties for various technological applications.

  10. Non-magnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser melting

    SciTech Connect

    Scarpulla, M.A.; Stone, P.R.; Sharp, I.D.; Haller, E.E.; Dubon, O.D.; Beeman, J.W.; Yu, K.M.

    2008-02-05

    The electronic and magnetic effects of intentional compensation with non-magnetic donors are investigated in the ferromagnetic semiconductors Ga1-xMnxAs and Ga1-xMnxP synthesized using ion implantation and pulsed-laser melting (II-PLM). It is demonstrated that compensation with non-magnetic donors and MnI have similarqualitative effects on materials properties. With compensation TC decreases, resistivity increases, and stronger magnetoresistance and anomalous Hall effect attributed to skew scattering are observed. Ga1-xMnxAs can be controllably compensated with Te through a metal-insulator transition through which the magnetic and electrical properties vary continuously. The resistivity of insulating Ga1-xMnxAs:Te can be described by thermal activation to the mobility edge and simply-activated hopping transport. Ga1-xMnxP doped with S is insulating at all compositions but shows decreasing TC with compensation. The existence of a ferromagnetic insulating state in Ga1-xMnxAs:Te and Ga1-xMnxP:S having TCs of the same order as the uncompensated materials demonstrates that localized holes are effective at mediating ferromagnetism in ferromagnetic semiconductors through the percolation of ferromagnetic 'puddles' which at low temperatures.

  11. Cast duplex stainless steel

    SciTech Connect

    Bond, A.P.; Grobner, P.J.; Poznansky, A.

    1985-02-19

    A casting alloy is provided containing about 0.02% to 0.05% carbon, about 23% to about 25% chromium, about 8% to 12% nickel, about 5% to 7% molybdenum, about 0.4% to 0.8% manganese, about 0.1% to 0.3% silicon, about 0.1% to 0.4% nitrogen, and the balance essentially iron, the alloy having a duplex austenite-ferrite grain structure, and being resistant to the corrosive effects of acids, chloride solutions and seawater.

  12. Nitriding of austenitic steels

    Microsoft Academic Search

    A. I. Nikonorova; F. R. Florensova

    1965-01-01

    1.We determined that it is possible to obtain a nonmagnetic nitrided layer on 0Kh20N4AG10 steel by heat treatment after nitriding.2.The recommended nitriding and heat treatment conditions are as follows: nitriding at 550°C for 48 h in ammonia + ammonium chloride; heating at 800°C for 2–15 min after nitriding and cooling in air.3.Nitriding and heat treatment of 0Kh20N4AG10 steel produce a

  13. Banding of MARaging steel

    Microsoft Academic Search

    C. Hays; R. P. Stemmler

    2000-01-01

    MAR-aging steels have gained a respectable position among design engineers who demand ultra-high strength, reasonable ductility,\\u000a and good fracture toughness, especially where outerspace and aerospace applications are concerned. This specialty steel category\\u000a of MAR-aging alloys owes its unique properties to a complex hardening reaction, which involves precipitation of uniform intragranular\\u000a ribbons (Ni3Mo phase) on dislocations during the treatment cycle. Like

  14. Life after Steel

    ERIC Educational Resources Information Center

    Mangan, Katherine

    2013-01-01

    Bobby Curran grew up in a working-class neighborhood in Baltimore, finished high school, and followed his grandfather's steel-toed bootprints straight to Sparrows Point, a 3,000-acre sprawl of industry on the Chesapeake Bay. College was not part of the plan. A gritty but well-paying job at the RG Steel plant was Mr. Curran's ticket to a secure…

  15. Periadolescent oral manganese exposure affects conditioned place preference by cocaine and conditioned place aversion by lithium chloride in rats 

    E-print Network

    Lee, Samuel Ming Hin

    2013-02-22

    Manganese neurotoxicity compromises basal ganglia functions that could affect the limbic system and drug sensitivity. Male rats were orally exposed to manganese chloride (0, 100, 200 mg/kg/day Mn) for 15 days starting at postnatal day (PND) 28...

  16. Arsenic mobilization in the critical zone: Oxidation by hydrous manganese oxide Jason S. Fischel, fischjs06@juniata.edu1

    E-print Network

    Sparks, Donald L.

    Arsenic mobilization in the critical zone: Oxidation by hydrous manganese oxide GEOC 112 Jason S manganese (Mn) oxides, even in low concentrations, to oxidize trace metals such as arsenic from arsenite [As

  17. Mitochondrial dysfunction and loss of Parkinson's disease-linked proteins contribute to neurotoxicity of manganese-containing welding fumes.

    PubMed

    Sriram, Krishnan; Lin, Gary X; Jefferson, Amy M; Roberts, Jenny R; Wirth, Oliver; Hayashi, Yusuke; Krajnak, Kristine M; Soukup, Joleen M; Ghio, Andrew J; Reynolds, Steven H; Castranova, Vincent; Munson, Albert E; Antonini, James M

    2010-12-01

    Welding generates complex metal aerosols, inhalation of which is linked to adverse health effects among welders. An important health concern of welding fume (WF) exposure is neurological dysfunction akin to Parkinson's disease (PD), thought to be mediated by manganese (Mn) in the fumes. Also, there is a proposition that welding might accelerate the onset of PD. Our recent findings link the presence of Mn in the WF with dopaminergic neurotoxicity seen in rats exposed to manual metal arc-hard surfacing (MMA-HS) or gas metal arc-mild steel (GMA-MS) fumes. To elucidate the molecular mechanisms further, we investigated the association of PD-linked (Park) genes and mitochondrial function in causing dopaminergic abnormality. Repeated instillations of the two fumes at doses that mimic ?1 to 5 yr of worker exposure resulted in selective brain accumulation of Mn. This accumulation caused impairment of mitochondrial function and loss of tyrosine hydroxylase (TH) protein, indicative of dopaminergic injury. A fascinating finding was the altered expression of Parkin (Park2), Uchl1 (Park5), and Dj1 (Park7) proteins in dopaminergic brain areas. A similar regimen of manganese chloride (MnCl(2)) also caused extensive loss of striatal TH, mitochondrial electron transport components, and Park proteins. As mutations in PARK genes have been linked to early-onset PD in humans, and because welding is implicated as a risk factor for parkinsonism, PARK genes might play a critical role in WF-mediated dopaminergic dysfunction. Whether these molecular alterations culminate in neurobehavioral and neuropathological deficits reminiscent of PD remains to be ascertained. PMID:20798247

  18. Blood manganese concentrations among first-grade schoolchildren in two South African cities.

    PubMed

    Röllin, Halina; Mathee, Angela; Levin, Jonathan; Theodorou, Penny; Wewers, Francois

    2005-01-01

    Little information exists on the environmental exposures to low levels of organometallic manganese (a principal combustion product from manganese-containing fuel additives) and public health. This study was undertaken to establish biological and environmental levels of manganese among first-grade schoolchildren in the South African cities of Johannesburg and Cape Town. The study was undertaken subsequent to partial introduction of the manganese-containing fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) to South African petrol in the Johannesburg region only, about 24 months prior to the commencement of the study, and in anticipation of possible future increases in MMT use in the rest of the country. This study involved the measurement of manganese concentrations in the blood of the total number of 814 of grade one schoolchildren (430 and 384 in Cape Town and Johannesburg, respectively), and in water supplies, soil, and classroom dust at a total number of 21 participating schools. The results indicated higher concentrations of manganese in school soil (P=0.0007) and dust (P=0.0071) samples from Johannesburg relative to Cape Town. Similarly, the mean blood manganese concentration in Johannesburg study subjects (9.80 microg/L, SD 3.59) was significantly higher than that in Cape Town study subjects (6.74 microg/L, SD 3.47), after allowing for the clustering effect within schools and adjusting for the confounding effect of population group (P<0.0001). The blood manganese levels of 4.2% and 12.5% of children in Cape Town and Johannesburg, respectively, equaled or exceeded 14 microg/L, the upper normal reference value specified by the Agency for Toxic Substances Disease Registry (ATSDR, 2000). Importantly, levels of manganese in blood were found to be significantly associated with concentrations of manganese in classroom dust at schools. PMID:15476738

  19. Visible and near-infrared spectra of manganese oxides: Detecting high manganese phases in Curiosity Mastcam multispectral images

    NASA Astrophysics Data System (ADS)

    Hardgrove, C. J.; Lanza, N.; Bell, J. F., III; Wiens, R. C.; Johnson, J. R.; Morris, R. V.

    2014-12-01

    The Mars Science Laboratory Curiosity rover's Chemcam instrument has identified manganese in relatively high abundance on several rock surfaces. The manganese abundances are several orders of magnitude greater than has been previously identified on Mars, indicating the presence of a manganese-rich phase. Although the specific phase has yet to be identified, these results suggest that the martian surface may have been much more highly oxidizing than has previously been recognized. The presence of a manganese-rich phase could provide an additional indicator of habitable aqueous environments. Given the importance of manganese for understanding past habitability, and the high abundances identified with Chemcam, we investigate the utility of using Mastcam multispectral imaging surveys to identify areas for subsequent detailed analysis with Chemcam. Vempati et al. showed that Mn3+ affect the reflectance spectra of Mn-bearing minerals. Specifically, relatively weak features due to electronic transitions and crystal field effects are observed in Mn-enriched hematites and geothites at 454, 554, 596 and 700 nm. The Mastcam-34 medium angle camera has filter band-passes at 550, 675 and 750nm, and we will explore the utility of using these bands (or combinations thereof) to determine if there is a contribution of Mn-bearing phases on spectra, specifically those that have been identified as having elevated Mn with Chemcam. The most common Mn-bearing mineral phase in terrestrial varnishes, Birnessite, has charge-transfer features that are similar to Fe-oxides but are centered at slightly longer wavelength band positions. Longer wavelength features are also common for other Mn-oxides, and this could be used to distinguish these phases from other Fe-oxide components. In this study we will present visible to near-infrared (0.4 - 3 µm) reflectance spectra on a suite of Mn-oxide laboratory standards. The set of standards includes Mn-oxide abundances that vary from less than 1 up to ~75 wt.%. Spectra will be downsampled to Mastcam bandpasses to determine if the effects of Mn-bearing phases could be identified from Mastcam multispectral observations in Gale Crater.

  20. Synthesis, characterization, and physicochemical properties of manganese(III) and manganese(V)-oxo corrolazines.

    PubMed

    Lansky, David E; Mandimutsira, Beaven; Ramdhanie, Bobby; Clausén, Maria; Penner-Hahn, James; Zvyagin, S A; Telser, Joshua; Krzystek, J; Zhan, Riqiang; Ou, Zhongping; Kadish, Karl M; Zakharov, Lev; Rheingold, Arnold L; Goldberg, David P

    2005-06-27

    The structural and physicochemical properties of the manganese-corrolazine (Cz) complexes (TBP8Cz)Mn(V)O (1) and (TBP8Cz)Mn(III) (2) (TBP = p-tert-butylphenyl) have been determined. Recrystallization of 2 from toluene/MeOH resulted in the crystal structure of (TBP8Cz)Mn(III)(CH3OH) (2 x MeOH). The packing diagram of 2 x MeOH reveals hydrogen bonds between MeOH axial ligands and meso N atoms of adjacent molecules. Solution binding studies of 2 with different axial ligands (Cl-, Et3PO, and Ph3PO) reveal strong binding, corroborating the preference of the Mn(III) ion for a five-coordinate environment. High-frequency and field electron paramagnetic resonance (HFEPR) spectroscopy of solid 2 x MeOH shows that 2 x MeOH is best described as a high-spin (S = 2) Mn(III) complex with zero-field splitting parameters typical of corroles. Structural information on 1 was obtained through an X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) study and compared to XANES/EXAFS data for 2 x MeOH. The XANES data for 1 shows an intense pre-edge transition characteristic of a high-valent metal-oxo species, and a best fit of the EXAFS data gives a short Mn-O bond distance of 1.56 A, confirming the structure of the metal-oxo unit in 1. Detailed spectroelectrochemical studies of 1 and 2 were performed revealing multiple reversible redox processes for both complexes, including a relatively low potential for the Mn(V) --> Mn(IV) process in 1 (near 0.0 V vs saturated calomel reference electrode). Chemical reduction of 1 results in the formation of a Mn(III)Mn(IV)(mu-O) dimer as characterized by electron paramagnetic resonance spectroscopy. PMID:15962955

  1. New nanocrystalline manganese oxides as cathode materials for lithium batteries : electron microscopy, electrochemical and X-ray absorption studies

    E-print Network

    Paris-Sud XI, Université de

    1 New nanocrystalline manganese oxides as cathode materials for lithium batteries : electron.F. Abstract New nanostructured manganese oxi-iodides were prepared by redox reaction of sodium permanganate: manganese oxide, lithium batteries, nanomaterials Corresponding author: Pierre Strobel, tel. 33 476 887 940

  2. Assessment of Bioaccumulation, Neuropathology, and Neurobehavior Following Subchronic (90 Days) Inhalation in Sprague–Dawley Rats Exposed to Manganese Phosphate

    Microsoft Academic Search

    Louise Normandin; Gaétan Carrier; Phillip F. Gardiner; Greg Kennedy; Alan S. Hazell; Donna Mergler; Roger F. Butterworth; Suzanne Philippe; Joseph Zayed

    2002-01-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic manganese (Mn) compound added to unleaded gasoline. It has been suggested that the combustion products of MMT containing Mn, such as manganese phosphate, could cause neurological symptoms similar to Parkinson's disease in humans. The aim of this work was to investigate the exposure–response relationship of bioaccumulation, neuropathology, and neurobehavior following a subchronic inhalation

  3. 40 CFR 721.10253 - Butanedioic acid, 2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

  4. 40 CFR 721.10253 - Butanedioic acid, 2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

  5. 40 CFR 721.10253 - Butanedioic acid, 2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc...2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

  6. Nonoccupational environmental exposure to manganese is linked to deficits in peripheral and central olfactory function.

    PubMed

    Guarneros, Marco; Ortiz-Romo, Nahum; Alcaraz-Zubeldia, Mireya; Drucker-Colín, René; Hudson, Robyn

    2013-11-01

    Manganese is of growing concern as a toxic air pollutant. It is readily transported from the olfactory epithelium to the olfactory bulb, and unlike other metals, it is transported transynaptically to structures deep within the brain. However, little is known regarding the possible effect of nonoccupational exposure to manganese on olfactory function. Using the Sniffin' Sticks test battery, we compared the olfactory performance of subjects from a manganese mining district living <1 km from a manganese processing plant, with nonexposed subjects living 50 km from the closest source of exposure (N = 30/group). Groups were matched for age, sex, and schooling, and none had ever worked in mining-related activities. Concentrations of manganese in hair were measured as a biomarker of exposure; exposed subjects had significantly higher concentrations than nonexposed subjects. They were also significantly outperformed by the nonexposed subjects on all olfactory measures (threshold, discrimination, and identification), indicating adverse effects of manganese exposure on a range of olfactory functions, including those involving higher order cognitive processes. This contrasts with previous findings showing adverse peripheral but not central effects on olfactory function of big city air pollution, which mostly consists of toxicants known to affect the olfactory epithelium but with lower transynaptic transport capacity compared with manganese. We conclude that nonoccupational exposure to airborne manganese is associated with decrements in both peripheral and central olfactory function. PMID:24097266

  7. Effects of iron and manganese on the formation of HAAs upon chlorinating Chlorella vulgaris

    Microsoft Academic Search

    Fei Ge; Xiuzhen Wu; Na Wang; Runliang Zhu; Tong Wang; Yin Xu

    2011-01-01

    The major objective of the present study was to investigate the role of iron and manganese on the formation of haloacetic acids (HAAs) when algae are chlorinated at different pHs. The results showed that both iron and manganese can reduce the yields of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) on chlorinating green alga Chlorella vulgaris (C. vulgaris) at a

  8. Manganese-alumina-ceramic glass eliminates rigid controls necessary in bonding metals to ceramics

    NASA Technical Reports Server (NTRS)

    Hollar, E. L.

    1968-01-01

    Matrix of manganese-alumino-silicate glass simplifies the processes of metallizing alumina ceramics. Because the manganese in the glass is preoxidized to the 2 plus state by firing in nitrogen, the ceramic can be metallized in dry hydrogen. Lengthening the firing time permits a lower metallizing temperature.

  9. The trial of regeneration of used impregnated activated carbons after manganese sorption

    Microsoft Academic Search

    Ewa Okoniewska; Joanna Lach; Ma?gorzata Kacprzak; Ewa Neczaj

    2008-01-01

    In recent years, the increasing level of underground water shows a high iron and manganese concentrations, thus, the technology of water treatment requires application of processes for Fe and Mn removal. Within a literature, many treatment processes have been proposed for manganese removal from drinking water, however very often they do not comply with the obligatory quality standards and are

  10. From manganism to manganese-induced parkinsonism: a conceptual model based on the evolution of exposure.

    PubMed

    Lucchini, Roberto G; Martin, Christopher J; Doney, Brent C

    2009-01-01

    Manganism is a distinct medical condition from Parkinson's disease. Manganese exposure scenarios in the last century generally have changed from the acute, high-level exposure conditions responsible for the occurrence of manganism to chronic exposure to much lower levels. Such chronic exposures may progressively extend the site of manganese deposition and toxicity from the globus pallidus to the entire area of the basal ganglia, including the substantia nigra pars compacta involved in Parkinson's disease. The mechanisms of manganese neurotoxicity from chronic exposure to very low levels are not well understood, but promising information is based on the concept of susceptibility that may place individuals exposed to manganese at a higher risk for developing Parkinsonian disturbances. These conditions include mutations of genes which play important pathogenetic roles in both Parkinsonism and in the regulation of manganese transport and metabolism. Liver function is also important in manganese-related neurotoxicity and sub-clinical impairment may increase the risk of Parkinsonism. The purpose and scope of this report are to explore the literature concerning manganese exposure and potential subclinical effects and biological pathways, impairment, and development of diseases such as Parkinsonism and manganism. Inhalation and ingestion of manganese will be the focus of this report. PMID:20012385

  11. The effects of salt, manganese, and density on life history traits in Hesperis matronalis L. from

    E-print Network

    The effects of salt, manganese, and density on life history traits in Hesperis matronalis L. from at local adapta- tion in Hesperis matronalis L. to salinity and manganese (Mn). Plants collected from three'adaptation locale de l'Hesperis matronalis L. à la salinité et au manganèse (Mn). Ils ont cultivé en serres, sous

  12. Disposition, behavior, and toxicity of methylcyclopentadienyl manganese tricarbonyl in the mouse.

    PubMed

    Komura, J; Sakamoto, M

    1992-11-01

    The disposition and toxicity of methylcyclopentadienyl manganese tricarbonyl (MMT), a potential substitute for lead in gasoline, was studied to investigate the different adverse effects in ddY mice after chronic oral administration at 0.5 g/kg in food for 12 months. There was no significant difference in intake between the control mice and the mice exposed to MMT (MMT group), but those given MMT suppressed weight significantly. The manganese content in the organs of the MMT group was 4.4-1.5 times significantly higher than that of the control group. In the MMT group, the manganese content was highest in the kidney, followed by the liver, thyroid gland, sublingual gland, and prostate gland. The blood manganese level in the MMT group was about 8 times higher than that in the control group. The urinary excretion of manganese in the MMT group was 5.4% of the daily oral intake. The organometallic form of the manganese involved is apparently absorbed more readily than inorganic forms. The stronger toxicity of MMT to the tissue than that of inorganic manganese is attributed to the significantly higher blood and tissue levels of manganese in the MMT group. PMID:1444591

  13. Application of pharmacokinetic data to the risk assessment of inhaled manganese

    Microsoft Academic Search

    David C. Dorman; Melanie F. Struve; Harvey J. Clewell III; Melvin E. Andersen

    2006-01-01

    There is increased interest within the scientific community concerning the neurotoxicity of manganese owing in part to the use of methylcyclopentadienyl manganese tricarbonyl (MMT) as a gasoline fuel additive and an enhanced awareness that this essential metal may play a role in hepatic encephalopathy and other neurologic diseases. Neurotoxicity generally arises over a prolonged period of time and results when

  14. Biological manganese removal from acid mine drainage in constructed wetlands and prototype bioreactors

    Microsoft Academic Search

    Kevin B. Hallberg; D. Barrie Johnson

    2005-01-01

    Mine drainage waters vary considerably in the range and concentration of heavy metals they contain. Besides iron, manganese is frequently present at elevated concentrations in waters draining both coal and metal mines. Passive treatment systems (aerobic wetlands and compost bioreactors) are designed to remove iron by biologically induced oxidation\\/precipitation. Manganese, however, is problematic as it does not readily form sulfidic

  15. Multiedge refinement of extended x-ray-absorption fine structure of manganese zinc ferrite nanoparticles

    Microsoft Academic Search

    S. Calvin; E. E. Carpenter; B. Ravel; V. G. Harris; S. A. Morrison

    2002-01-01

    The structure of nanoparticle manganese zinc ferrites synthesized by a reverse micellar method is determined by analysis of the extended x-ray-absorption fine structure in combination with other techniques. Both empirical and theoretical standards are employed; manganese, zinc, and iron edges are refined simultaneously. It is determined that samples synthesized under similar conditions sometimes exhibit a markedly different distribution of cations

  16. Cost Effective Synthesis of Bulk Thermoelectric Higher Manganese Silicide for Waste Heat Recovery and Environmental Protection

    Microsoft Academic Search

    Xinghua Shi; Zahra Zamanipour; Arash Mehdizadeh Dehkordi; Kenneth F. Ede; Jerzy S. Krasinski; Daryoosh Vashaee

    2012-01-01

    Higher manganese silicide (HMS) is a useful thermoelectric material for waste heat recovery in medium to high temperature range. It is made from two of the most abundant materials on earth. Moreover, it is non-toxic and environmentally responsible. A low-cost, scalable, and quick method of synthesizing bulk thermoelectric higher manganese silicide is proposed for its industrial manufacturing. Heat treatment alloying

  17. Evolution of Microstructures During Austempering of Ductile Irons Alloyed with Manganese and Copper

    NASA Astrophysics Data System (ADS)

    Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar

    2013-03-01

    The influences of relatively high manganese (0.45 through 1.0 wt pct) and copper (0.56 through 1.13 wt pct) contents on microstructure development and phase transformation in three austempered ductile irons have been studied. The experimental ductile irons alloyed with copper and manganese are found to be practically free from intercellular manganese segregation. This suggests that the positive segregation of manganese is largely neutralized by the negative segregation of copper when these alloying elements are added in appropriate proportions. The drop in unreacted austenite volume (UAV) with increasing austempering temperature and time is quite significant in irons alloyed with copper and manganese. The ausferrite morphology also undergoes a transition from lenticular to feathery appearance of increasing coarseness with the increasing austempering temperature and time. SEM micrographs of the austempered samples from the base alloy containing manganese only, as well as copper plus manganese-alloyed irons, clearly reveal the presence of some martensite along with retained austenite and ferrite. X-ray diffraction analysis also confirms the presence of these phases. SEM examination further reveals the presence of twinned martensite in the copper plus manganese-alloyed samples. The possibility of strain-induced transformation of austenite to martensite during austempering heat treatment is suggested.

  18. Anti-inflammatory effects of recombinant human manganese superoxide dismutase on adjuvant arthritis in rats

    Microsoft Academic Search

    M. Shingu; S. Takahashi; M. Ito; N. Hamamatu; Y. Suenaga; Y. Ichibangase; M. Nobunaga

    1994-01-01

    The anti-inflammatory effects of recombinant human manganese superoxide dismutase on adjuvant arthritis was investigated. Local application of this manganese superoxide dismutase given every 2 days not only significantly reduced foot swelling but also retarded radiological bone destruction in adjuvant arthritis. Copper zinc superoxide dismutase had little effect on foot swelling.

  19. Manganese porphyrin multilayer films assembled on ITO electrodes via zirconium phosphonate chemistry: chemical and electrochemical

    E-print Network

    Manganese porphyrin multilayer films assembled on ITO electrodes via zirconium phosphonate University, 2145 Sheridan Road, Evanston, IL 60208-3113 A supported manganese porphyrin-based oxidation oxidation of the film-based catalyst at pH 11 generated MnV (O)(porphyrin)(H2O) intermediate at a potential

  20. THE ACCUMULATION AND DISTRIBUTION OF VANADIUM, IRON, AND MANGANESE IN SOME SOLITARY ASCIDIANS

    Microsoft Academic Search

    H. MICHIBATA; T. TERADA; N. ANADA; K. YAMAKAWA; T. NUMAKUNAI

    The vanadium, iron, and manganese contents of 15 species of solitary ascidians belonging to the suborders Phlebobranchia and Stolidobranchia were determined by thermal neutron activation analysis. Vanadium was detectable in all species exam med. In general, the vanadium content in various tissues ofthe Phlebobranchia was considerably higher than the iron and manganese contents. The blood cells especially contained a large

  1. Pretreatment of lignocellulosic materials with hydrogen peroxide in presence of manganese compounds

    Microsoft Academic Search

    M. Takagi

    1987-01-01

    Pretreatment of lignocellulosic materials such as newspaper, rice straw, pulp waste, and municipal solid waste with hydrogen peroxide in the presence of manganese compounds greatly enhances their susceptibility to enzymatic saccharification. This pretreatment can be achieved using rather mild conditions with only a minimal decrease in the recovery and little change in composition. Manganese salts in this hydrogen peroxide pretreatment

  2. New. J. Chem., 1992, 16, 633-642 THE PHOTOCHEMISTRY OF CHROMIUM, MANGANESE,

    E-print Network

    Suslick, Kenneth S.

    New. J. Chem., 1992, 16, 633-642 THE PHOTOCHEMISTRY OF CHROMIUM, MANGANESE, AND IRON PORPHYRIN, 799 7. ABSTRACT. - A review is presented of the photochemistry of porphyrin complexes of the first row transition metals, particularly those of chromium, manganese, and iron. Their photochemistry has revealed

  3. Steel bonded dense silicon nitride compositions and method for their fabrication

    DOEpatents

    Landingham, Richard L. (Livermore, CA); Shell, Thomas E. (Tracy, CA)

    1987-01-01

    A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500.degree. C. in a vacuum with a refractory material and the stainless steel is then pressure bonded to the metallic coated surface by brazing it with nickel-copper-silver or nickel-copper-manganese alloys at a temperature in the range of about 850.degree. to 950.degree. C. in a vacuum. The two-stage bonding technique minimizes the temperature-expansion mismatch between the dissimilar materials.

  4. Steel bonded dense silicon nitride compositions and method for their fabrication

    DOEpatents

    Landingham, R.L.; Shell, T.E.

    1985-05-20

    A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500/sup 0/C in a vacuum with a refractory material and the stainless steel is then pressure bonded to the metallic coated surface by brazing it with nickel-copper-silver or nickel-copper-manganese alloys at a temperature in the range of about 850/sup 0/ to 950/sup 0/C in a vacuum. The two-stage bonding technique minimizes the temperature-expansion mismatch between the dissimilar materials.

  5. Maternal Blood Manganese and Early Neurodevelopment: The Mothers and Children’s Environmental Health (MOCEH) Study

    PubMed Central

    Chung, Soo Eun; Ha, Eun-Hee; Kim, Boong-Nyun; Ha, Mina; Kim, Yangho; Hong, Yun-Chul; Park, Hyesook; Oh, Se-Young

    2015-01-01

    Background Manganese is an essential trace element and common component of water, soil, and air. Prenatal manganese exposure may affect fetal and infantile neurodevelopment, but reports on in utero manganese exposure and infant neurodevelopment are rare. Objective This study was conducted to investigate a relationship between maternal blood manganese level and neurodevelopment of infants at 6 months of age. Methods Data were obtained from the Mothers and Children’s Environmental Health (MOCEH) birth cohort study. The study population included 232 pairs of pregnant women and their infants at 6 months of age. Maternal blood manganese was measured at term, just before delivery. Mental and psychomotor development in infancy was assessed at 6 months of age using the Bayley Scales of Infant Development. The relationship between maternal blood manganese level and the mental and psychomotor development indexes (MDI and PDI) was estimated for manganese modeled as a linear and as a categorical variable and using penalized splines for nonlinear modeling. Results Mean ± SD maternal blood manganese concentration was 22.5 ± 6.5 ?g/L. After adjustment for potential confounders, blood manganese was used as a continuous variable in a linear and nonlinear model. Associations between maternal blood manganese and MDI and PDI scores followed an inverted U-shape dose–response curve after adjustment for potential confounders, with lower scores associated with both low and high blood concentrations [MDI: likelihood-ratio test (LRT) p = 0.075, PDI: LRT p = 0.038]. Associations of both outcomes with increasing blood manganese shifted from positive to negative at concentrations of 24–28 ?g/L in this cohort of term, normal birth weight children. Conclusion Although no cut-off point has been established to define manganese toxicity, both high and low blood manganese levels may be associated with neurobehavioral function in infants. Citation Chung SE, Cheong HK, Ha EH, Kim BN, Ha M, Kim Y, Hong YC, Park H, Oh SY. 2015. Maternal blood manganese and early neurodevelopment: the Mothers and Children’s Environmental Health (MOCEH) study. Environ Health Perspect 123:717–722; http://dx.doi.org/10.1289/ehp.1307865 PMID:25734517

  6. Sol-gel synthesis and adsorption properties of mesoporous manganese oxide

    NASA Astrophysics Data System (ADS)

    Ivanets, A. I.; Kuznetsova, T. F.; Prozorovich, V. G.

    2015-03-01

    Sol-gel synthesis of mesoporous xerogels of manganese oxide with different phase compositions has been performed. The manganese oxide sols were obtained by redox reactions of potassium permanganate with hydrogen peroxide or manganese(II) chloride in aqueous solutions. The isotherms of the low-temperature adsorption-desorption of nitrogen with manganese oxide xerogels treated at 80, 200, 400, and 600°C were measured. The samples were studied by electron microscopy and thermal and XRD analysis. The phase transformation and the changes in the adsorption and capillary-condensation properties of manganese oxide were shown to depend on the sol synthesis conditions and the temperature of the thermal treatment of the gel. The X-ray amorphous samples heated at 80°C were shown to have low values of the specific surface; at higher temperatures, the xerogel crystallized into mixed phases with various compositions and its surface area increased at 200-400°C and decreased at 600°C.

  7. Composites of manganese oxide with carbon materials as catalysts for the ozonation of oxalic acid.

    PubMed

    Orge, C A; Órfão, J J M; Pereira, M F R

    2012-04-30

    Manganese oxide and manganese oxide-carbon composites were prepared and tested as catalysts for the removal of oxalic acid by ozonation. Their performances were compared with the parent carbon material (activated carbon or carbon xerogel) used to prepare the composites. Oxalic acid degradation by carbon materials is slower than that attained with manganese oxide or manganese oxide-carbon composites. A complete degradation after 90 and 45 min of reaction was obtained for carbon materials and for the catalysts containing manganese, respectively. The ozonation in the presence of the prepared composites are supposed to occur mainly by surface reactions, following a direct oxidation mechanism by molecular ozone and/or surface oxygenated radicals. PMID:22341747

  8. Influence of Substrate and Tissue Manganese on the IAA-Oxidase System in Cotton 12

    PubMed Central

    Taylor, D. M.; Morgan, Page W.; Joham, Howard E.; Amin, J. V.

    1968-01-01

    Tissue manganese was found to influence the indoleacetic acid (IAA) system of cotton over a wide range of concentrations. The cofactor and inhibitor activities of the IAA-oxidase system were affected as the concentration of manganese in the tissue was varied. Maximum inhibitor activity was found in leaf extracts from the plants grown in 0.5 mg/l manganese (Hoagland's level). The inhibitor activity decreased in the leaf extracts of plants grown at concentrations of manganese either higher or lower than 0.5 mg/l. Abnormally high IAA-oxidase activity was found in the leaves of plants grown in deficient levels of manganese (<0.0005, 0.005 mg/l) and the extracts from plants in the <0.0005 mg/l Mn treatment showed IAA-oxidase cofactor activity. PMID:16656758

  9. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

    PubMed Central

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

    2013-01-01

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

  10. ICME for Crashworthiness of TWIP Steels: From Ab Initio to the Crash Performance

    NASA Astrophysics Data System (ADS)

    Güvenç, O.; Roters, F.; Hickel, T.; Bambach, M.

    2015-01-01

    During the last decade, integrated computational materials engineering (ICME) emerged as a field which aims to promote synergetic usage of formerly isolated simulation models, data and knowledge in materials science and engineering, in order to solve complex engineering problems. In our work, we applied the ICME approach to a crash box, a common automobile component crucial to passenger safety. A newly developed high manganese steel was selected as the material of the component and its crashworthiness was assessed by simulated and real drop tower tests. The crashworthiness of twinning-induced plasticity (TWIP) steel is intrinsically related to the strain hardening behavior caused by the combination of dislocation glide and deformation twinning. The relative contributions of those to the overall hardening behavior depend on the stacking fault energy (SFE) of the selected material. Both the deformation twinning mechanism and the stacking fault energy are individually well-researched topics, but especially for high-manganese steels, the determination of the stacking-fault energy and the occurrence of deformation twinning as a function of the SFE are crucial to understand the strain hardening behavior. We applied ab initio methods to calculate the stacking fault energy of the selected steel composition as an input to a recently developed strain hardening model which models deformation twinning based on the SFE-dependent dislocation mechanisms. This physically based material model is then applied to simulate a drop tower test in order to calculate the energy absorption capacity of the designed component. The results are in good agreement with experiments. The model chain links the crash performance to the SFE and hence to the chemical composition, which paves the way for computational materials design for crashworthiness.

  11. Manganese-Enhanced Magnetic Resonance Imaging of Traumatic Brain Injury.

    PubMed

    Talley Watts, Lora; Shen, Qiang; Deng, Shengwen; Chemello, Jonathan; Duong, Timothy Q

    2015-07-01

    Calcium dysfunction is involved in secondary traumatic brain injury (TBI). Manganese-enhanced MRI (MEMRI), in which the manganese ion acts as a calcium analog and a MRI contrast agent, was used to study rats subjected to a controlled cortical impact. Comparisons were made with conventional T2 MRI, sensorimotor behavior, and immunohistology. The major findings were: (1) Low-dose manganese (29?mg/kg) yielded excellent contrast with no negative effects on behavior scores relative to vehicle; (2) T1-weighted MEMRI was hyperintense in the impact area at 1-3?h, hypointense on day 2, and markedly hypointense with a hyperintense area surrounding the core on days 7 and/or 14, in contrast to the vehicle group, which did not show a biphasic profile; (3) in the hyperacute phase, the area of hyperintense T1-weighted MEMRI was larger than that of T2 MRI; (4) glial fibrillary acidic protein staining revealed that the MEMRI signal void in the impact core and the hyperintense area surrounding the core on day 7 and/or 14 corresponded to tissue cavitation and reactive gliosis, respectively; (5) T2 MRI showed little contrast in the impact core at 2?h, hyperintense on day 2 (indicative of vasogenic edema), hyperintense in some animals but pseudonormalized in others on day 7 and/or 14; (6) behavioral deficit peaked on day 2. We concluded that MEMRI detected early excitotoxic injury in the hyperacute phase, preceding vasogenic edema. In the subacute phase, MEMRI detected contrast consistent with tissue cavitation and reactive gliosis. MEMRI offers novel contrasts of biological processes that complement conventional MRI in TBI. PMID:25531419

  12. Sol-gel route to the tunneled manganese oxide cryptomelane

    SciTech Connect

    Ching, S.; Roark, J.L. [Connecticut College, New London, CT (United States)] [Connecticut College, New London, CT (United States); Duan, N.; Suib, S.L. [Univ. of Connecticut, Storr, CT (United States)] [Univ. of Connecticut, Storr, CT (United States)

    1997-03-01

    The sol-gel reaction between KMnO{sub 4} and fumaric acid in a 3:1 mole ratio generates a flocculant gel that serves as a precursor to the tunneled manganese oxide, cryptomelane. The elemental composition of sol-gel cryptomelane has been determined to be K{sub 0.12}MnO{sub 2.0-} (H{sub 2}O){sub 0.09}. Further characterization has been performed using powder X-ray diffraction, scanning electron microscopy, and Auger electron spectroscopy. The sol-gel process is heavily dependent on reactant concentration. Solutions that are too concentrated produce the layered manganese oxide birnessite, whereas overly dilute reactions yield mixtures of cryptomelane and Mn{sub 2}O{sub 3}. The preference for cryptomelane over birnessite correlates with low potassium content in the gel. The sol-gel procedure for synthesizing cryptomelane is not easily transferred to the preparation of analogous manganese oxides with different tunnel cations. Reactions that employ permanganates other than KMnO{sub 4} generally yield Mn{sub 2}O{sub 3}, with cryptomelane being a minor product at best. Thermal analyses of cryptomelane gels indicate that calcination proceeds through a series of stages that involve loss of water, loss of residual organics, conversion to cryptomelane, and finally degradation to Mn{sub 3}O{sub 4}. The extraction of potassium ions from sol-gel cryptomelane by various foreign cations is minimal, with the loss of K{sup +} being on the order of 10%. 49 refs., 7 figs., 3 tabs.

  13. Serum prolactin in subjects occupationally exposed to manganese.

    PubMed

    Mutti, A; Bergamaschi, E; Alinovi, R; Lucchini, R; Vettori, M V; Franchini, I

    1996-01-01

    To evaluate whether or not occupational exposure to manganese (Mn) affects basal levels of serum prolactin (PRL), a cross-sectional study was carried out in 31 occupationally-exposed workers, aged 39.2 years (DS 7.9) exposed to manganese (Mn) dusts for 14.5 years (range: 5 to 29 years) in a ferroalloy producing plant. Thirty-four industrial workers not exposed to neurotoxic chemicals and of comparable age composed the control group. Airborne Mn concentrations in dusts of the furnace area ranged 210 to 980 micrograms/m3, which is below the current American Conference of Governmental Industrial Hygienists (ACGIH)-recommended threshold limit value-time weighted average (TLV-TWA) of 1 mg/m3. Manganese concentrations in blood Mn (MnB) and in urine (MnU) were significantly higher in Mn-exposed workers as compared to control workers. The Mn-exposed workers showed significantly higher serum prolactin (PRL) levels with the geometric mean (GM) being 9.77 ng/ml with a geometric standard deviation (GSD) of 1.69 as compared to controls (GM 4.65 ng/ml, GSD 1.78, p < 0.001). Serum PRL was negatively related to age and positively correlated with both MnB and MnU. Dose-effect relationships were still significant in partial correlation analysis after control for age. The prevalence of abnormally high PRL values was consistent with a dose-response relationship. The observed increase in serum PRL among Mn-exposed workers suggests an impairment of tonic inhibition by tubero-infundibular dopaminergic neurons. The correlation between PRL and both MnB and MnU in samples collected at least 48 h from the last exposure suggests that such indices provide an estimation of the target dose. PMID:8834356

  14. Pharmacokinetics of inhaled manganese phosphate in male Sprague-Dawley rats following subacute (14-day) exposure.

    PubMed

    Vitarella, D; Wong, B A; Moss, O R; Dorman, D C

    2000-03-15

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as a gasoline octane enhancer. Manganese phosphate is the primary respirable (PM(2.5)) MMT-combustion product emitted from the automobile tailpipe. The goal of this study was to determine the exposure-response relationship for inhaled manganese phosphate in adult male CD rats. Rats were exposed 6-h/day for either 5 days/week (10 exposures) or 7 days/week (14 exposures) to manganese phosphate at 0, 0.03, 0.3, or 3 mg Mn/m(3) (MMAD congruent with 1.5 micrometer). The following tissues collected at the end of the 2-week exposure: plasma, erythrocytes, olfactory bulb, striatum, cerebellum, lung, liver, femur, and skeletal muscle (n = 6 rats/exposure group) were analyzed for manganese content by neutron activation analysis. Intravenous (54)MnCl(2) tracer studies were also conducted following the 14th exposure (n = 6 rats/concentration), and whole-body gamma spectrometry was performed immediately after injection and at 1, 2, 4, 8, 12, and 16 weeks after (54)MnCl(2) administration. Increased manganese concentrations were observed in olfactory bulb, lung, femur, and skeletal muscle following exposure to 3 mg Mn/m(3) (10 or 14 exposures). Increased manganese concentrations were also observed in olfactory bulb, striatum, and lung following exposure to 0.3 mg Mn/m(3) (14 exposures only). Red blood cell and plasma manganese concentrations were increased only in rats exposed to 3 mg Mn/m(3) (10 exposures). Rats exposed to 3 mg Mn/m(3) also had an increased whole-body manganese clearance rate when compared to air-exposed control animals. Our results suggest that the rat olfactory bulb may accumulate more manganese than other brain regions following inhalation exposure. PMID:10702367

  15. Intellectual Impairment in School-Age Children Exposed to Manganese from Drinking Water

    PubMed Central

    Bouchard, Maryse F.; Sauvé, Sébastien; Barbeau, Benoit; Legrand, Melissa; Brodeur, Marie-Ève; Bouffard, Thérèse; Limoges, Elyse; Bellinger, David C.; Mergler, Donna

    2011-01-01

    Background Manganese is an essential nutrient, but in excess it can be a potent neurotoxicant. Despite the common occurrence of manganese in groundwater, the risks associated with this source of exposure are largely unknown. Objectives Our first aim was to assess the relations between exposure to manganese from drinking water and children’s intelligence quotient (IQ). Second, we examined the relations between manganese exposures from water consumption and from the diet with children’s hair manganese concentration. Methods This cross-sectional study included 362 children 6–13 years of age living in communities supplied by groundwater. Manganese concentration was measured in home tap water (MnW) and children’s hair (MnH). We estimated manganese intake from water ingestion and the diet using a food frequency questionnaire and assessed IQ with the Wechsler Abbreviated Scale of Intelligence. Results The median MnW in children’s home tap water was 34 ?g/L (range, 1–2,700 ?g/L). MnH increased with manganese intake from water consumption, but not with dietary manganese intake. Higher MnW and MnH were significantly associated with lower IQ scores. A 10-fold increase in MnW was associated with a decrease of 2.4 IQ points (95% confidence interval: ?3.9 to ?0.9; p < 0.01), adjusting for maternal intelligence, family income, and other potential confounders. There was a 6.2-point difference in IQ between children in the lowest and highest MnW quintiles. MnW was more strongly associated with Performance IQ than Verbal IQ. Conclusions The findings of this cross-sectional study suggest that exposure to manganese at levels common in groundwater is associated with intellectual impairment in children. PMID:20855239

  16. A X-Ray Absorption Spectroscopy Study of Manganese Containing Compounds and Photosynthetic Spinach Chloroplasts.

    NASA Astrophysics Data System (ADS)

    Kirby, Jon Allan

    The manganese sites in chloroplasts, long thought to be involved in photosynthetic oxygen evolution have been examined and partially characterized by X-ray Absorption Spectroscopy (XAS) using synchrotron radiation. The local environment about the manganese atoms is estimated from an analysis of the extended X-ray Absorption Fine Structure (EXAFS). Comparisons with and simulations of the manganese EXAFS for several reference compounds leads to a model in which the chloroplast manganese atoms are contained in a binuclear complex similar to di-u-oxo -tetrakis-(2,2'-bipyridine) dimanganese. It is suggested that the partner metal is another manganese. The bridging ligands are most probably oxygen. The remaining manganese ligands are carbon, oxygen, or nitrogen. A roughly linear correlation between the X-ray K edge onset energy and the "coordination charge" of a large number of manganese coordination complexes and compounds has been developed. Entry of the chloroplast manganese edge energy onto this correlation diagram establishes that the active pool of manganese is in an oxidation state greater than +2. If the manganese is in a dimeric form the oxidation states are most probably (II,III). Underlying these results is an extensive data analysis methodology. The method developed involves the use of many different background removal techniques, Fourier transforms and ultimately curve fitting to the modulations in the x-ray absorption cross sections. A large number of model compounds were used to evaluate the analysis method. These analyses are used to show that the two major curve fitting models available are essentially equivalent. Due to its greater versatility, the theoretical model of Teo and Lee is preferred (J. Am. Chem. Soc. (1979), 101, 2815). The results are also used to determine the informational limitations of XAS within the limits of the present understanding of X-ray absorption phenomena by inner shell electrons for atoms with atomic number greater than that of argon.

  17. High-frequency electromagnetic properties of the manganese ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeng, Min; Liu, Jue; Yue, Ming; Yang, Haozhe; Dong, Hangrong; Tang, Wukui; Jiang, He; Liu, Xiaofang; Yu, Ronghai

    2015-05-01

    Manganese (MnFe2O4) nanoparticles are prepared via a facile solvothermal method. The electromagnetic properties are investigated in 1-18 GHz, indicating the MnFe2O4 nanoparticles are the promising materials to be applied as microwave absorbers. The wave absorbing mechanism can be attributed to the dielectric loss, magnetic loss, and the synergetic effect. The permittivity dispersion behavior is explained by Debye dipolar relation expression. The complex permeability is analyzed using Landau-Lifshitz-Gilbert equation. Natural resonance, exchange resonance, and eddy current loss arise at different frequencies.

  18. Diaqua­bis­(nitrato-?O)bis­(pyridine-?N)manganese(II)

    PubMed Central

    Alam, Naveed; Shahid, Muhammad; Rauf, M. Khawar

    2013-01-01

    The structure of the title manganese complex, [Mn(NO3)2(C5H5N)2(H2O)2], consists of discrete monomeric entities with Mn2+ ions located on centres of inversion. The metal cation is octahedrally coordinated by a trans-N2O4 donor set with the pyridine N atoms located in the apical positions. Discrete mol­ecules are linked by O—H?O hydrogen bonds into one-dimensional supra­molecular infinite chains along the b and c axes. PMID:23476361

  19. Diaqua-bis-(nitrato-?O)bis-(pyridine-?N)manganese(II).

    PubMed

    Alam, Naveed; Shahid, Muhammad; Rauf, M Khawar

    2013-01-01

    The structure of the title manganese complex, [Mn(NO3)2(C5H5N)2(H2O)2], consists of discrete monomeric entities with Mn(2+) ions located on centres of inversion. The metal cation is octahedrally coordinated by a trans-N2O4 donor set with the pyridine N atoms located in the apical positions. Discrete mol-ecules are linked by O-H?O hydrogen bonds into one-dimensional supra-molecular infinite chains along the b and c axes. PMID:23476361

  20. Nanostructured lithium nickel manganese oxides for lithium-ion batteries

    Microsoft Academic Search

    Haixia Deng; Ilias Belharouak; Russel E. Cook; Huiming Wu; Yang-Kook Sun; Khalil Amine

    2010-01-01

    Nanostructured lithium nickel manganese oxides were investigated as advanced positive electrode materials for lithium-ion batteries designated to power plug-in hybrid electric vehicles and all-electric vehicles. The investigation included material characterization and electrochemical testing. In cell tests, the Li{sub 1.375}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.4375} composition achieved high capacity (210 mAh g¹) at an elevated rate (230 mA g¹), which makes this material

  1. Manganese ion-assisted assembly of superparamagnetic graphene oxide microbowls

    SciTech Connect

    Tian, Zhengshan [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China); School of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan 467000 (China); Xu, Chunxiang, E-mail: xcxseu@seu.edu.cn; Li, Jitao; Zhu, Gangyi; Xu, Xiaoyong; Dai, Jun; Shi, Zengliang; Lin, Yi [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)

    2014-03-24

    A facile manganese ion Mn(II)-assisted assembly has been designed to fabricate microbowls by using graphene oxide nanosheets as basic building blocks, which were exfoliated ultrasonically from the oxidized soot powders in deionized water. From the morphology evolution observations of transmission electron microscope and scanning electron microscope, a coordinating-tiling-collapsing manner is proposed to interpret the assembly mechanism based on attractive Van der Waals forces, ?-? stacking, and capillary action. It is interesting to note that the as-prepared microbowls present a room temperature superparamagnetic behavior.

  2. Linear Thermal Expansion Coefficients of Higher Manganese Silicide Compounds

    NASA Astrophysics Data System (ADS)

    Allam, Ali; Boulet, Pascal; Record, Marie-Christine

    The linear thermal expansion coefficients ?L of the higher manganese silicide compounds are calculated using a combined approach involving Density-Functional Theory calculations, an empirical relation and experimental data. Since it has been reported that the linear thermal expansion coefficient and the cohesive energy are inversely proportional to each other, we calculated by DFT methods the cohesive energies of a set of selected disilicide compounds and using the corresponding experimental data for ?L we determined the coefficient of proportionality. From the empirical relation so obtained, the linear thermal expansion coefficients of the HMS in the ‘a’ and ‘c’ directions were calculated.

  3. Magnetism in cubic manganese-rich Heusler compounds

    NASA Astrophysics Data System (ADS)

    Wollmann, Lukas; Chadov, Stanislav; Kübler, Jürgen; Felser, Claudia

    2014-12-01

    Manganese-rich Heusler compounds are attracting much interest in the context of spin transfer torque and rare-earth free hard magnets. Here we give a comprehensive overview of the magnetic properties of noncentrosymmetric cubic Mn2-based Heusler materials, which are characterized by an antiparallel coupling of magnetic moments on Mn atoms. Such a ferrimagnetic order leads to the emergence of new properties that are absent in ferromagnetic centrosymmetric Heusler structures. In terms of the band structure calculations, we explain the formation of this magnetic order and the Curie temperatures. This overview is intended to establish guidelines for a basic understanding of magnetism in Mn2-based Heusler compounds.

  4. Manganese complexes with bicarbonate and sulfate in natural water

    USGS Publications Warehouse

    Hem, J.D.

    1963-01-01

    The association constant for the dissolved species MnHCO3+ was experimentally determined to be 63. From this value and a published constant for the species MNSO4 aq., a diagram was prepared showing per cent of dissolved manganese complexed in the presence of 10 to 10,000 p.p.m. bicarbonate and 1.0 to 10,000 p.p.m. sulfate. The rate of oxidation of Mn+2 in aerated water is greatly increased by increasing pH, and is retarded when SO4-2and HCO3- are present.

  5. Magnetic ordering in perovskites containing manganese and cobalt

    Microsoft Academic Search

    I. O. Troyanchuk; N. V. Samsonenko; N. V. Kasper; H. Szymczak; A. Nabialek

    1997-01-01

    The magnetization measurement of systems with the nominal formula 0953-8984\\/9\\/39\\/013\\/img8 (R = Eu, Gd, Tb, Y) has been made. It has been found that 0953-8984\\/9\\/39\\/013\\/img9 and 0953-8984\\/9\\/39\\/013\\/img10 are weak ferromagnets of Dzialoshinsky - Moriya type whereas 0953-8984\\/9\\/39\\/013\\/img11 is an antiferromagnet. The substitution of manganese ions by cobalt ones leads to the appearance of different magnetic states: cluster-spin-glass-like 0953-8984\\/9\\/39\\/013\\/img12, inhomogeneous ferromagnets

  6. Pharmacokinetic evaluation of the equivalency of gavage, dietary, and drinking water exposure to manganese in f344 rats.

    PubMed

    Foster, Melanie L; Bartnikas, Thomas B; Johnson, Laura C; Herrera, Carolina; Pettiglio, Michael A; Keene, Athena M; Taylor, Michael D; Dorman, David C

    2015-06-01

    Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10?ppm), high manganese diet (200?ppm), manganese-supplemented drinking water, and manganese gavage treatment groups. Animals in the drinking water and gavage groups were given the 10?ppm manganese diet and supplemented with manganese chloride (MnCl2) in drinking water or once-daily gavage to provide a daily manganese intake equivalent to that seen in the high-manganese diet group. No statistically significant difference in body weight gain or terminal body weights was seen. Rats were anesthetized following 7 and 61 exposure days, and samples of bile and blood were collected. Rats were then euthanized and striatum, olfactory bulb, frontal cortex, cerebellum, liver, spleen, and femur samples were collected for chemical analysis. Hematocrit was unaffected by manganese exposure. Liver and bile manganese concentrations were elevated in all treatment groups on day 61 (relative to controls). Increased cerebellum manganese concentrations were seen in animals from the high-manganese diet group (day 61, relative to controls). Increased (relative to all treatment groups) femur, striatum, cerebellum, frontal cortex, and olfactory bulb manganese concentrations were also seen following gavage suggesting that dose rate is an important factor in the pharmacokinetics of oral manganese. These data will be used to refine physiologically based pharmacokinetic models, extending their utility for manganese risk assessment by including multiple dietary exposures. PMID:25724921

  7. Brazing titanium to stainless steel

    NASA Technical Reports Server (NTRS)

    Batista, R. I.

    1980-01-01

    Titanium and stainless-steel members are usually joined mechanically for lack of any other effective method. New approach using different brazing alloy and plating steel member with nickel resolves problem. Process must be carried out in inert atmosphere.

  8. Continuous steel production and apparatus

    DOEpatents

    Peaslee, Kent D. (Rolla, MO); Peter, Jorg J. (McMinnville, OR); Robertson, David G. C. (Rolla, MO); Thomas, Brian G. (Champaign, IL); Zhang, Lifeng (Trondheim, NO)

    2009-11-17

    A process for continuous refining of steel via multiple distinct reaction vessels for melting, oxidation, reduction, and refining for delivery of steel continuously to, for example, a tundish of a continuous caster system, and associated apparatus.

  9. Local control of magnetic damping in ferromagnetic/non-magnetic bilayers by interfacial intermixing induced by focused ion-beam irradiation

    SciTech Connect

    King, J. A.; Burn, D. M.; Sallabank, E. A.; Hindmarch, A. T.; Atkinson, D., E-mail: del.atkinson@durham.ac.uk, E-mail: abarman@bose.res.in [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Ganguly, A.; Pal, S.; Barman, A., E-mail: del.atkinson@durham.ac.uk, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology and Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700 098 (India); Hase, T. P. A. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2014-06-16

    The influence of interfacial intermixing on the picosecond magnetization dynamics of ferromagnetic/non-magnetic thin-film bilayers was studied. Low-dose focused-ion-beam irradiation was used to induce intermixing across the interface between a 10?nm Ni{sub 81}Fe{sub 19} layer and a 2–3?nm capping layer of either Au or Cr. Time-resolved magneto-optical Kerr effect was used to study magnetization dynamics as a function of ion-beam dose. With an Au cap, the damping of the un-irradiated bilayer was comparable with native Ni{sub 81}Fe{sub 19} and increased with increasing ion dose. In contrast, for Ni{sub 81}Fe{sub 19}/Cr the damping was higher than that for native Ni{sub 81}Fe{sub 19}, but the damping decreased with increasing dose.

  10. Study on spin polarization of non-magnetic atom in diluted magnetic semiconductor: The case of Al-doped 4H-SiC

    NASA Astrophysics Data System (ADS)

    He, Ming; He, X.; Lin, L.; Song, B.; Zhang, Z. H.

    2014-11-01

    Determining the atomic origin of magnetism in non-magnetic elements doped dilute magnetic semiconductors (DMS) is a key issue to understand the room temperature ferromagnetism. Here, using electron magnetic circular dichroism (EMCD), an element-selectivity and high spatial resolution technique, we provide unambiguous experimental evidence: spin polarization of carbon atoms contributes to the local magnetic moments of Al-doped 4H-SiC DMS. The result is further confirmed by first-principle calculations. The atomic origin of the magnetism in Al-doped 4H-SiC was pinpointed. Electron magnetic circular dichroism signals were observed in nonmagnetic C atoms. No electron magnetic circular dichroism signals were observed in Si and Al atoms. The spin polarization of C atoms was confirmed by first principles calculations.

  11. Rashba Effect in Non-Magnetic InGaAs/GaAsSb Resonant Tunneling Diodes Enhanced By Transverse Magnetic Field

    NASA Astrophysics Data System (ADS)

    de Sousa, J. Silvano; Detz, H.; Klang, P.; Gornik, E.; Strasser, G.; Smoliner, J.

    2011-12-01

    A large Rashba splitting enhanced by an in-plane magnetic field is observed in non-magnetic InGaAs/GaAsSb/InGaAs resonant tunneling diodes over a wide range of temperatures. The current resonances split by the Rashba effect reveal peak to valley ratios up to 2.5:1, the energy spacing between the split peaks reaches values up to 30 meV at B = 5T. The observed peak splitting is robust and can be observed at temperatures as high as T = 180K. The largest Rashba parameter determined from the split peak positions is ? = 0.78 eVÅ. This value is consistent with literature values reported for InGaAs based devices.

  12. Process for making a martensitic steel alloy fuel cladding product

    DOEpatents

    Johnson, Gerald D. (Kennewick, WA); Lobsinger, Ralph J. (Kennewick, WA); Hamilton, Margaret L. (Richland, WA); Gelles, David S. (West Richland, WA)

    1990-01-01

    This is a very narrowly defined martensitic steel alloy fuel cladding material for liquid metal cooled reactors, and a process for making such a martensitic steel alloy material. The alloy contains about 10.6 wt. % chromium, about 1.5 wt. % molybdenum, about 0.85 wt. % manganese, about 0.2 wt. % niobium, about 0.37 wt. % silicon, about 0.2 wt. % carbon, about 0.2 wt. % vanadium, 0.05 maximum wt. % nickel, about 0.015 wt. % nitrogen, about 0.015 wt. % sulfur, about 0.05 wt. % copper, about 0.007 wt. % boron, about 0.007 wt. % phosphorous, and with the remainder being essentially iron. The process utilizes preparing such an alloy and homogenizing said alloy at about 1000.degree. C. for 16 hours; annealing said homogenized alloy at 1150.degree. C. for 15 minutes; and tempering said annealed alloy at 700.degree. C. for 2 hours. The material exhibits good high temperature strength (especially long stress rupture life) at elevated temperature (500.degree.-760.degree. C.).

  13. EAF STAINLESS STEEL DUST PROCESSING

    Microsoft Academic Search

    G. M. Denton; N. A. Barcza; P. D. Scott; T. Fulton

    During the production of stainless steel iron, between 30 and 70 kg of dust and fine waste is generated per ton of steel. Mintek has developed the EnviroplasTM process for the treatment of solid wastes from the metallurgical industry, especially steel plant dusts, without requiring agglomeration to produce inert slag and at the same time recover metal values such as

  14. Microbial-Influenced Corrosion of Corten Steel Compared with Carbon Steel and Stainless Steel in Oily Wastewater by Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Mansouri, Hamidreza; Alavi, Seyed Abolhasan; Fotovat, Meysam

    2015-05-01

    The microbial corrosion behavior of three important steels (carbon steel, stainless steel, and Corten steel) was investigated in semi petroleum medium. This work was done in modified nutrient broth (2 g nutrient broth in 1 L oily wastewater) in the presence of Pseudomonas aeruginosa and mixed culture (as a biotic media) and an abiotic medium for 2 weeks. The behavior of corrosion was analyzed by spectrophotometric and electrochemical methods and at the end was confirmed by scanning electron microscopy. The results show that the degree of corrosion of Corten steel in mixed culture, unlike carbon steel and stainless steel, is less than P. aeruginosa inoculated medium because some bacteria affect Corten steel less than other steels. According to the experiments, carbon steel had less resistance than Corten steel and stainless steel. Furthermore, biofilm inhibits separated particles of those steels to spread to the medium; in other words, particles get trapped between biofilm and steel.

  15. Why did Nature choose manganese to make oxygen?

    PubMed Central

    Armstrong, Fraser A

    2007-01-01

    This paper discusses the suitability of manganese for its function in catalysing the formation of molecular oxygen from water. Manganese is an abundant element. In terms of its inherent properties, Mn has a particularly rich redox chemistry compared with other d-block elements, with several oxidizing states accessible. The most stable-state Mn2+ behaves like a Group 2 element—it is mobile, weakly complexing, easily taken up by cells and redox-inactive in simple aqueous media. Only in the presence of suitable ligands does Mn2+ become oxidized, so it provides an uncomplicated building unit for the oxygen-evolving centre (OEC). The intermediate oxidation states Mn(III) and Mn(IV) are strongly complexed by O2? and form robust mixed-valence poly-oxo clusters in which the Mn(IV)/Mn(III) ratio can be elevated, one electron at a time, accumulating oxidizing potential and capacity. The OEC is a Mn4CaOx cluster that undergoes sequential oxidations by P680+ at potentials above 1?V, ultimately to a super-oxidized level that includes one Mn(V) or a Mn(IV)-oxyl radical. The latter is powerfully oxidizing and provides the crucial ‘power stroke’ necessary to generate an O–O bond. This leaves a centre still rich in Mn(IV), ensuring a rapid follow-through to O2. PMID:17971329

  16. Chromium and manganese interactions in streptozocin-diabetic rats

    SciTech Connect

    Davis, M.L.; Jarrett, C.R.; Adeleye, B.O.; Stoecker, B.J. (Oklahoma State Univ., Stillwater (United States))

    1991-03-15

    Weanling male rats were fed casein-based diets low in chromium and manganese ({minus}Cr-MN) or supplemented with 1 ppm chromium as chromium chloride (+Cr) and/or 55 ppm manganese as manganous carbonate in a factorial design. After 7 weeks on the experimental diets, half of the rats in each group were injected on 2 consecutive days with 55 mg/kg streptozocin (STZ) in citrate buffer pH 4. Four weeks after injection, serum glucose in the diabetic group supplement with both Cr and Mn was not different from non-diabetic animals; however, diabetic animals in {minus}Cr groups or in the +Cr-Mn group had significantly elevated serum glucose. Serum insulin was reduced by STZ. A significant interaction between Mn and diabetes affected serum cortisol concentrations. More new tissue was formed on a polyvinyl sponge inserted under the skin in +Mn animals. In this study, the STZ animals were more sensitive than the control animals to dietary Cr and Mn concentrations.

  17. Solution synthesis and characterization of lithium manganese oxide cathode materials

    SciTech Connect

    Voigt, J.A.; Boyle, T.J.; Doughty, D.H. [and others

    1995-07-01

    A nonaqueous coprecipitation process has been developed to prepare controlled stoichiometry lithium manganese oxalate precipitates. The process involved mixing a methanolic Li-Mn nitrate solution with a methanolic solution containing tetramethylammonium oxalate as the precipitating agent. The resulting oxalates were readily converted to a variety of phase pure lithium manganese oxides at moderate temperatures ({le}600{degrees}C), where the phase formed was determined by the initial Li/Mn ratio in the starting solution. Metal cation dopants have been incorporated into the oxalate precipitate by dissolving the appropriate metal nitrate in the Li-Mn precursor solution The various starting solutions, oxalate precipitates, and calcined oxides have been extensively characterized using a variety of techniques, including {sup 7}Li NMR, TGA/DTA, SEM, and XRD. Results indicate that a strong interaction occurs between Li and Mn in the nitrate solution which carries over into the oxalate phase during precipitation. The morphology and the crystallite size of the oxide powders were shown to be controlled by the morphology of the oxalate precursor and the oxalate calcination temperature, respectively. The results of initial cathode performance tests with respect to dopant type (Al, Ni, Co) and concentration for LiMn{sub 2}O{sub 4} are also reported.

  18. Speciation and toxicological relevance of manganese in humans.

    PubMed

    Michalke, Bernhard; Halbach, Stefan; Nischwitz, Volker

    2007-07-01

    Although manganese is an essential trace element, concerns are rising about the Mn exposure of humans being related to neurotoxic effects. This review summarizes several aspects of this topic to provide updated information on Mn related investigations, including chemical speciation of Mn-compounds. The paper starts with some chemical aspects of Mn and its compounds, enlightening oxidation states in general and in biological matrices. This is followed by considerations on natural sources of human exposure, on occupational sources and on anthropogenically caused environmental sources, for example from the use of methylcyclopentadienyl manganese tricarbonyl (MMT). Next, the paper deals with Mn levels in the human organism, showing normal Mn concentrations in various tissues or body fluids, and continues with the toxicology of Mn, i.e. absorption, distribution and excretion. Of specific concern is the transfer of Mn to the brain which is the relevant neurotoxic target. In this context, parallels and differences between primary and Mn-dependent Parkinsonism are discussed, concluding with a risk assessment and a consideration of susceptible groups. The main part of this review focuses on recent investigations on Mn speciation. Analytical problems and their solutions are also described for correct identification of relevant Mn-compounds in matrices of human origin. Finally, future needs are discussed, such as further investigations on those Mn-species which may overcome neural barrier control, on disease-modulated barrier control, on susceptibility to certain Mn-species, and on the interaction of Mn with Fe-homeostasis in the brain. PMID:17607384

  19. The EPA health risk assessment of methylcyclopentadienyl manganese tricarbonyl (MMT).

    PubMed

    Davis, J M; Jarabek, A M; Mage, D T; Graham, J A

    1998-02-01

    This paper describes the U.S. Environmental Protection Agency's assessment of potential health risks associated with the possible widespread use of a manganese (Mn)-based fuel additive, methylcyclopentadienyl manganese tricarbonyl (MMT). This assessment was significant in several respects and may be instructive in identifying certain methodological issues of general relevance to risk assessment. A major feature of the inhalation health risk assessment was the derivation of Mn inhalation reference concentration (RfC) estimates using various statistical approaches, including benchmark dose and Bayesian analyses. The exposure assessment component used data from the Particle Total Exposure Assessment Methodology (PTEAM) study and other sources to estimate personal exposure levels of particulate Mn attributable to the permitted use of MMT in leaded gasoline in Riverside, CA, at the time of the PTEAM study; on this basis it was then possible to predict a distribution of possible future exposure levels associated with the use of MMT in all unleaded gasoline. Qualitative as well as quantitative aspects of the risk characterization are summarized, along with inherent uncertainties due to data limitations. PMID:9523444

  20. Raman Microscopy of Lithium-Manganese-Rich Cathodes

    SciTech Connect

    Ruther, Rose E [ORNL; Callender, Andrew F. [Tennessee Technological University; Zhou, Hui [ORNL; Martha, Surendra [Indian Institute of Technology, Hyderabad; Nanda, Jagjit [ORNL

    2014-01-01

    Lithium rich, manganese rich composites with general formula xLi2MnO3 (1-x)LiMO2 are promising candidates for high capacity and high voltage cathodes for lithium ion batteries. Lithium rich oxides crystallize as a nanocomposite of layered phases whose structure further evolves with electrochemical cycling. Raman spectroscopy is potentially a powerful tool to monitor the crystal chemistry and correlate phase changes with electrochemical behavior. While several groups have reported Raman spectra of lithium rich oxides, the data show considerable variability in terms of both the vibrational features observed and their interpretation. In this study Raman microscopy is used to investigate lithium-rich manganese-rich cathodes as a function of average charge and electrochemical cycling. LMR-NMC cycled at elevated temperature (60 C) has a modified crystal structure which may account for some of the observed increase in capacity. Contrary to some reports, no growth of a spinel phase is observed. However, analysis of the Raman spectra does indicate the structure of LMR-NMC deviates significantly from an ideal layered phase. The results also highlight the importance of using low laser power and large sample sizes to obtain consistent data sets.