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1

Low-carbon manganese carburizing steels  

Microsoft Academic Search

High-manganese low-carbon steels may be a new and promising class of carburizing steels. They do not contain expensive elements or those in short supply, are simple in production, and possess high strength properties and sufficient plasticity of the core. The obtaining in the case of metastable austenite which becomes harder during service opens new possibilities for increasing the life of

L. S. Malinov; L. I. Yakushechkina; E. L. Malinova

1985-01-01

2

Properties of silicon — Manganese steel with vanadium and zirconium  

Microsoft Academic Search

1.Steel 36G2S with concentrations of carbon and manganese at the lower limit of the range specified does not satisfy the requi rements for the mechanical properties of steel of strength group K for casting pipe (GQST 632-64).2.The addition of small amounts of vanadium and zirconium to medium-carbon silicon-manganese steel increases the strength and ductile characteristics of the steel and ensures

V. N. Zikeev; B. P. Kolesnik; D. A. Litvinenko; V. T. Ababkov; L. I. Guzevataya

1969-01-01

3

Phase stability of high manganese austenitic steels for cryogenic applications  

E-print Network

The aim of this work is to study the austenitic stability against a' martensitic transformation of three non-magnetic austenitic steels : a new stainless steel X2CrMnNiMoN 19-12-11-1 grade, a traditional X8CrMnNiN 19-11-6 grade and a high manganese X8MnCrNi 28-7-1 grade. Measurements of relative magnetic susceptibility at room temperature are performed on strained tensile specimens at 4.2 K. A special extensometer for high precision strain measurements at low temperature has been developed at CERN to test specimens up to various levels of plastic strain. Moreover, the high precision strain recording of the extensometer enables a detailed study of the serrated yield phenomena associated with 4.2 K tensile testing and their influence on the evolution of magnetic susceptibility. The results show that high Mn contents increase the stability of the austenitic structure against a' martensitic transformation, while keeping high strength at cryogenic temperature. Moreover, proper elaboration through primary and possi...

Couturier, K

2000-01-01

4

Strain hardening of low-carbon manganese steels  

Microsoft Academic Search

Low-carbon steels with a high manganese content (3–5%) are highly susceptible to strain aging, which is accompanied by hardening due to precipitation of finely dispersed cementite particles. The increase of the manganese content, due to the displacement character of the transformation of austenite, increase the amount of carbon in solution and leads to precipitation hardening similar to the intermediate transformation

V. D. Kal'ner; B. I. Beilin; L. G. Shevyakova; I. P. Arsent'eva

1980-01-01

5

Phase transformations in a manganese-alloyed austenitic stainless steel  

SciTech Connect

The increasing demands placed on the corrosion resistance of stainless steels has led to the successive development of more highly alloyed materials. In this context nitrogen has shown considerable value as an alloying element but its use is restricted by a solubility limit of approximately 0.2 wt% in conventional austenitic stainless steel grades. Manganese increases the nitrogen solubility appreciably and for this reason there has also been an increased interest in its use as an alloying addition but numerous questions remain to be answered about the effect of both nitrogen and manganese on structural stability. Although much work has been published on the precipitation of secondary phases in CrNi(Mo) stainless steels, there is a relative paucity of information available on manganese-alloyed steels. Brandis et al. investigated precipitation in a 25Cr 17Ni 3Mo 6Mn 0.2Nb steel and found no manganese-enriched phases to occur. Sigma phase was the predominant intermetallic precipitate at low nitrogen contents while higher nitrogen contents retarded the onset of sigma phase precipitation but caused the appearance of chi phase. Boothby et al. investigated a 12Cr 11-35Ni (3Mo) steel in which the nickel was partially replaced by 20 or 30% manganese and found the precipitation of the intermetallic sigma, chi and Laves phases to be promoted by manganese, although again no manganese-enriched phases were observed. Fritscher demonstrated however the existence in the Fe-Cr-Ni system of a brittle ternary Y phase containing 30--60% manganese which was destabilized by nitrogen. The present work represents part of a study designed to gain greater understanding of the precipitation and sensitization behavior of highly alloyed austenitic stainless steels and concentrates on the influence of nitrogen additions up to 0.5wt% on precipitation of secondary phases in a 20Cr 18Ni 4.5Mo 10Mn steel.

Jargelius-Pettersson, R.F.A. (Swedish Inst. for Metals Research, Stockholm (Sweden))

1994-05-01

6

Elaboration and characterization of yttrium implanted low manganese steel  

Microsoft Academic Search

Low manganese steel samples were yttrium implanted using ion implantation technique. Sample compositions and structures were investigated before and after yttrium implantations to determine the yttrium distribution in low manganese steel. Yttrium implantation depth profiles were characterized using conventional techniques such as X-ray photoelectron spectroscopy (XPS), reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), glancing angle X-ray diffraction (GAXRD)

E. Caudron; H Buscail; R Cueff; Y. P Jacob; M. F Stroosnijder

1999-01-01

7

Yttrium implantation effect on low manganese–carbon steel  

Microsoft Academic Search

Low manganese–carbon steels were implanted with yttrium using the ion implantation method. Compositional and structural analyses were carried out before and after yttrium implantation by several techniques such as Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, reflection high energy electron diffraction, X-ray diffraction and glancing angle X-ray diffraction to observe the yttrium implantation effect on low manganese–carbon steel.

E Caudron; H Buscail; V. A. C Haanapel; Y. P Jacob; M. F Stroosnijder

2000-01-01

8

Manganese.  

PubMed

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

Barceloux, D G

1999-01-01

9

Manganese  

SciTech Connect

Manganese (Mn) is a hard, brittle, gray-white transition metal, with the most numerous oxidation states of the elements in the first series of the Periodic Table. Since the manganese atom can donate up to seven electrons from its outer two shells, manganese compounds exist with valences from -3 to +7, the most common being +2, +4, and +7. Due to its sulfur-fixing, deoxidizing, and alloying properties, as well as its low cost, the principal commercial application for manganese is in iron and steel production. Manganese is also employed in non-ferrous metallurgy, batteries and chemical processes. Although potentially harmful to the respiratory and nervous systems, manganese is an essential element for animals and humans, and a micronutrient for plants.

Major-Sosias, M.A.

1996-10-01

10

Vanadium carbonitride in low-carbon manganese steel  

Microsoft Academic Search

1.Low-carbon (0.03%) manganese steel (2% Mn) has a structure of ferrite with equilibrium grains, the boundaries of which are free of inclusions.2.Alloying of the steel with nitrogen and vanadium leads to precipitation of V(C, N) in ferrite, the platelets with dimensions of 70–150 Å. However, precipitation of V(C, N) in cleavage planes {100} weakens the atomic bonds, inducing embrittlement of

V. N. Nikitin; A. P. Gulyaev; N. I. Karchevskaya; Ya. M. Akhundov

1976-01-01

11

Manganese partitioning in low carbon manganese steel during annealing  

Microsoft Academic Search

For 6Mn16 steel experimental soft annealing at 625 °C for periods from 1 h to 60 h and modeling with Thermo-Calc were performed to estimate the partitioning of alloying elements, in particular Mn, between ferrite, cementite and austenite. Using transmission electron microscopy and X-ray analysis it was established that the increase of Mn concentration in carbides to a level 7%–11.2% caused a local

J. Lis; A. Lis; C. Kolan

2008-01-01

12

On the deformation mechanisms in single crystal Hadfield manganese steels  

SciTech Connect

Austenitic manganese steel, so called Hadfield manganese steel, is frequently used in mining and railroad frog applications requiring excessive deformation and wear resistance. Its work hardening ability is still not completely understood. Previous studies attributed the work-hardening characteristics of this material to dynamic strain aging or an imperfect deformation twin, a so-called pseudotwin. Unfortunately, these previous studies have all focused on polycrystalline Hadfield steels. To properly study the mechanisms of deformation in the absence of grain boundary or texture effects, single crystal specimens are required. The purpose of this work is the following: (1) observe the inelastic stress-strain behavior of Hadfield single crystals in orientations where twinning and slip are individually dominating or when they are competing deformation mechanisms; and (2) determine the microyield points of Hadfield single crystals and use micro-mechanical modeling to predict the stress-strain response of a single crystal undergoing micro-twinning.

Karaman, I.; Sehitoglu, H.; Gall, K. [Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering] [Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering; Chumlyakov, Y.I. [Siberian Physical and Technical Inst., Tomsk (Russian Federation). Physics of Plasticity and Strength of Materials Lab.] [Siberian Physical and Technical Inst., Tomsk (Russian Federation). Physics of Plasticity and Strength of Materials Lab.

1998-02-13

13

Manganese partitioning in low carbon manganese steel during annealing  

SciTech Connect

For 6Mn16 steel experimental soft annealing at 625 deg. C for periods from 1 h to 60 h and modeling with Thermo-Calc were performed to estimate the partitioning of alloying elements, in particular Mn, between ferrite, cementite and austenite. Using transmission electron microscopy and X-ray analysis it was established that the increase of Mn concentration in carbides to a level 7%-11.2% caused a local decrease of the Ac{sub 1} temperature and led to the presence of austenite around the carbides. Thus, after cooling, small bainite-martensite or bainite-martensite-retained austenite (BM-A) islands were observed. A dispersion of carbides and a coarsening process were observed. The measured amount of Mn in the carbides was in good agreement with theoretical predictions.

Lis, J. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland); Lis, A. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland)], E-mail: lis@mim.pcz.czest.pl; Kolan, C. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland)

2008-08-15

14

Effect of manganese on the annealing texture and strain ratio of low-carbon steels  

Microsoft Academic Search

A correlation between the plastic strain ratio, or ? value, and the manganese content of laboratory-prepared, low-carbon steels\\u000a has been established. The$$\\\\bar r$$ value decreases consistently when manganese is increased from 0.05 to 0.56 pct. Excellent$$\\\\bar r$$ values are associated with manganese contents of 0.1 pct or less. The desirable (111) fiber texture in the low-manganese\\u000a steels is obtained through

Hsun Hu; S. R. Goodman

1970-01-01

15

Some interesting microstructures in very low carbon high manganese microalloyed steels  

Microsoft Academic Search

As part of an ongoing investigation into alternative compositions to the traditional controlled rolled HSLA or microalloyed steels, a series of very low carbon, high manganese, microalloyed steels were produced by Bhole and Yu that, after controlled rolling and normalizing, exhibited good strength-toughness properties comparable to the commercially available HSLA steels. Manganese is a strong austenite stabilizer and solid solution

S. D. Bhole; A. G. Fox

1993-01-01

16

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

E-print Network

??High manganese TWIP (TWinning Induced Plasticity) steels are particularly attractive for automotive applications because of their exceptional properties of strength combined with an excellent ductility.… (more)

Beal, Coline

2011-01-01

17

Effect of boron doping on the structural transformations and properties of low manganese steels  

Microsoft Academic Search

1.Doping of temper hardened steels containing 0.15–0.25% C with boron improves their bulk hardenability. As a result, the strength of boron containing low manganese steels attain the level of boronless steels with high manganese content. At the same time impact toughness and ductility remain practically unchanged.2.In the investigated steels doped with boron, boron containing inclusions may segregate; their composition and

G. Z. Koval'chuk; V. N. Yarmosh

1988-01-01

18

MnS precipitation in association with manganese silicate inclusions in Si\\/Mn deoxidized steel  

Microsoft Academic Search

When manganese silicate inclusions were formed during cooling from 1600 °C, manganese and sulfur contents in the manganese\\u000a silicate inclusions were much lower than their equilibrium values within the steel matrix, i.e., the steel matrix was supersaturated with Mn and S against the inclusions. The formation of a Mn-depleted zone around an\\u000a inclusion and the precipitation of a MnS phase

Han S. Kim; Hae-Geon Lee; Kyung-Shik Oh

2001-01-01

19

Comparison of the oxidation resistances of yttrium implanted low manganese and low manganese–carbon steels at high temperature  

Microsoft Academic Search

Yttrium implanted and unimplanted low manganese and low manganese–carbon steel samples were analyzed at T=700°C and under an oxygen partial pressure PO2=0.04 Pa for 24 h to show the yttrium implantation effect on sample high temperature oxidation resistances. Sample oxidation weight gains were studied by thermogravimetry and structural analyses were performed by in-situ high temperature X-ray diffraction (XRD) with the

E. Caudron; H Buscail

2000-01-01

20

Effect of titanium additions to low carbon, low manganese steels on sulphide precipitation  

Microsoft Academic Search

Recent developments of high strength line pipe steel have seen a decrease in carbon content from 0.25 wt% to less than 0.05 wt% and manganese to less than 1 wt% in an attempt to reduce centreline segregation. The sulphur content should be less than 0.008 wt% as well. However, recent papers argued that low manganese levels in pipeline steels have

Sima Aminorroaya-Yamini

2008-01-01

21

Hot corrosion resistances of yttrium-implanted and unimplanted low-manganese–carbon steels  

Microsoft Academic Search

Yttrium-implanted and unimplanted low-manganese–carbon steel samples were analyzed at T=700°C and under an oxygen partial pressure PO2=0.04 Pa for 24 h to observe the yttrium implantation effect on sample hot corrosion resistance. The yttrium implantation effect on low-manganese–carbon steel was investigated using several analytical and structural techniques such as Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), reflection high energy

E Caudron; H Buscail

2000-01-01

22

Occurrence of manganese-oxidizing microorganisms and manganese deposition during biofilm formation on stainless steel in a brackish surface water.  

PubMed

Abstract Biofilm formation on 316L stainless steel was investigated in a pilotscale flow-through system fed with brackish surface water using an alternating flow/stagnation/flow regime. Microbial community analysis by denaturing gradient gel electrophoresis and sequencing revealed the presence of complex microbial ecosystems consisting of, amongst others, Leptothrix-related manganese-oxidizing bacteria in the adjacent water, and sulfur-oxidizing, sulfate-reducing and slime-producing bacteria in the biofilm. Selective plating of the biofilm indicated the presence of high levels of manganese-oxidizing microorganisms, while microscopic and chemical analyses of the biofilm confirmed the presence of filamentous manganese-precipitating microorganisms, most probably Leptothrix species. Strong accumulation of iron and manganese occurred in the biofilm relative to the adjacent water. No evidence of selective colonization of the steel surface or biocorrosion was found over the experimental period. The overall results of this study highlight the potential formation of complex microbial biofilm communities in flow-through systems thriving on minor concentrations of manganese. PMID:19709183

Kielemoes, Jan; Bultinck, Isabelle; Storms, Hedwig; Boon, Nico; Verstraete, Willy

2002-01-01

23

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

E-print Network

to the liquid metal embrittlement (LME) phenomenon by hot tensile tests carried out on electro manganese austenitic steels - Liquid Metal Embrittlement - Cracking - Hot tensile tests - Gleeble - Zinc, as austenitic steels, they appear to be sensitive to liquid zinc embrittlement during welding, the liquid zinc

Paris-Sud XI, Université de

24

Microstructural and mechanical effects of nickel and manganese on high strength steel weld metals  

E-print Network

Microstructural and mechanical effects of nickel and manganese on high strength steel weld metals E Neural network modelling suggested that the impact strength of high-strength steel weld metals could with respect to Mn. Based on these predictions, shielded metal arc welding was used to prepare weld metals

Cambridge, University of

25

Effect of manganese on the martensite transformation temperature and properties of stainless steels at low temperatures  

Microsoft Academic Search

1.Stainless steels with 14%Cr, 3.8%Ni, and 0.4%Ti, depending on the manganese concentration (8–16%), can be divided into two groups according to the stability of austenite with respect to the ??a transformation: a) Steels containing 8–10%Mn have a ??a' transformation (below 0°C) and also a ??a? transformation; b) in steels with 12–16%Mn the transformation occurs only under the combined influence of

E. A. Ul'yanin; N. A. Sorokina; V. I. Fedorova

1968-01-01

26

Microstructure and properties of low manganese and niobium containing HIC pipeline steel  

Microsoft Academic Search

The paper describes the concept of using low manganese content in pipeline steels for hydrogen-induced cracking (HIC) applications. The microstructure of thermomechanically processed pipeline steel primarily consisted of polygonal ferrite and low fraction of pearlite. The cleanliness of the steel was evident as was the absence of centerline segregation. The microstructure contained high dislocation density, sub-boundaries and dislocation substructures. Fine-scale

S. S. Nayak; R. D. K. Misra; J. Hartmann; F. Siciliano; J. M. Gray

2008-01-01

27

Structure and properties of low-carbon high-manganese cast steels for cryogenic use  

Microsoft Academic Search

A low carbon content and a relatively high manganese\\/carbon ratio have a marked effect in promoting the toughness of Mn-C cast steels at low temperatures. In the case of a low carbon content, cast steel with an austenitic matrix containing epsilon-martensite has good mechanical properties at low temperatures. The advantage of the cast steel with a ..gamma.. + epsilon structure

L. S. Li; C. M. Wayman; G. S. Wei; D. Z. Yang

1982-01-01

28

Low Frequency-SAFT Inspection Methodology for Coarse-Grained Steel Rail Components (Manganese Steel Frogs)  

SciTech Connect

In the rail industry, sections of high strength Manganese steel are employed at critical locations in railroad networks. Ultrasonic inspections of Manganese steel microstructures are difficult to inspect with conventional means, as the propagation medium is highly attenuative, coarse-grained, anisotropic and nonhomogeneous in nature. Current in-service inspection methods are ineffective while pre-service X-ray methods (used for full-volumetric examinations of components prior to shipment) are time-consuming, costly, require special facilities and highly trained personnel for safe operations, and preclude manufacturers from inspecting statistically meaningful numbers of frogs for effective quality assurance. In-service examinations consist of visual inspections only and by the time a defect or flaw is visually detected, the structural integrity of the component may already be compromised, and immediate repair or replacement is required. A novel ultrasonic inspection technique utilizing low frequency ultrasound (100 to 500 kHz) combined with a synthetic aperture focusing technique (SAFT) for effective reduction of signal clutter and noise, and extraction of important features in the data, has proven to be effective for these coarse grained steel components. Results from proof-of-principal tests in the laboratory demonstrate an effective means to detect and localize reflectors introduced as a function of size and depth from the top of the frog rail. Using non-optimal, commercially available transducers coupled with the low-frequency/SAFT approach, preliminary evaluations were conducted to study the effects of the material microstructure on ultrasonic propagation, sensitivity and resolution in thick section frog components with machined side-drilled holes. Results from this study will be presented and discussed.

Diaz, Aaron A.; Andersen, Eric S.; Samuel, Todd J.

2004-11-01

29

Irradiation induced changes in the grain boundary chemistry of high-manganese low activation martensitic steels  

NASA Astrophysics Data System (ADS)

The effects of neutron irradiation (10 dpa at 638 K, FFTF/MOTA) on solute segregation to the grain boundaries in high-manganese martensitic steels were investigated using Auger electron spectroscopy (AES). The AES spectrum obtained from the grain boundaries in martensitic steels was significantly influenced by neutron irradiation. Neutron irradiation caused a marked increase in the amount of intergranular segregation of manganese in 12%Cr-6%Mn-1%W steel, while no significant increases in sulfur and/or phosphorus segregations were found in the steel. In 9%Cr-2%Mn-1%W steel, a large amount of silicon as well as a small amount of manganese segregation at grain boundaries was induced by the irradiation. The following mechanisms of irradiation induced embrittlement are proposed; (1) neutron irradiation induced intergranular segregation of manganese causes a reduction of grain boundary cohesive force, (2) intergranular segregation of silicon reduces carbon concentration at grain boundaries by a site competition mechanism resulting in the weakening of the grain boundary strength. Another possible explanation involves grain boundary precipitation.

Kimura, A.; Charlot, L. A.; Gelles, D. S.; Baer, D. R.; Jones, R. H.

1992-09-01

30

Manganese: it turns iron into steel (and does so much more)  

USGS Publications Warehouse

Manganese is a common ferrous metal with atomic weight of 25 and the chemical symbol Mn. It constitutes roughly 0.1 percent of the Earth’s crust, making it the 12th most abundant element. Its early uses were limited largely to pigments and oxidants in chemical processes and experiments, but the significance of manganese to human societies exploded with the development of modern steelmaking technology in the 1860s. U.S consumption of manganese is about 500,000 metric tons each year, predominantly by the steel industry. Because manganese is essential and irreplaceable in steelmaking and its global mining industry is dominated by just a few nations, it is considered one of the most critical mineral commodities for the United States.

Cannon, William F.

2014-01-01

31

Behavior of nitrogen in a nitrogen-containing chromium-manganese steel during electroslag remelting  

NASA Astrophysics Data System (ADS)

Electroslag remelting of a high-alloyed steel with high contents of nitrogen, chromium, and manganese in an electroslag furnace has been studied. CaF2-MgO-SiO2 slag developed at TsNIITMASh and allowing remelting process at a temperature of 1520-1560°C is used as a flux. It is found that electroslag remelting of high-alloyed steels with a high nitrogen concentration does not change the nitrogen content.

Linchevskii, B. V.; Rigina, L. G.; Takhirov, A. A.

2013-06-01

32

Corrosion Behavior of Low Alloy Steels Containing Manganese in Mixed Chloride Sulfate Solution  

NASA Astrophysics Data System (ADS)

The corrosion resistance of the low alloy steels was improved by the addition of Mn up to 2.0 wt pct due to grain refinement and the formation of a protective rust layer. On the other hand, the addition of 5.0 wt pct manganese decreased the corrosion resistance of low alloy steel due to the microstructural changes that hinder the formation of the protective rust layer.

Nam, Nguyen Dang; Kim, Min Jun; Kim, Jung Gu

2014-02-01

33

Cumulative fatigue damage in low cycle fatigue and gigacycle fatigue for low carbon–manganese steel  

Microsoft Academic Search

Typical tee and pipe components are subjected to thermal and mechanical loading histories which are variable and divided into two different regimes: low cycle fatigue and high cycle fatigue in steam generator vessel of nuclear power plants.Carbon–manganese steel A42 are often used in such applications. In order to investigate the cumulative damage of low cycle fatigue and gigacycle fatigue, the

Zhi Yong Huang; Danièle Wagner; Claude Bathias; Jean Louis Chaboche

2011-01-01

34

The microstructure and properties of a quenched and tempered low-carbon-manganese-niobium steel  

Microsoft Academic Search

The effects of rolling parameters (deformation schedule and finishing temperature), cooling rate (direct quench and air cool), and heat treatment have been investigated for a low carbon-manganese-niobium steel. Microstructure was characterized by optical and transmission electron microscopy, and correlated with tensile and impact properties. The best combination of strength and toughness was obtained by controlled rolling low in the austenite

J. D. Boyd

1976-01-01

35

Research of selected properties of two types of high manganese steel wires  

NASA Astrophysics Data System (ADS)

The article presents results of tests that aimed at establishing the impact of deformation on properties of wires made of two types of high manganese steels. The deformation process was carried out with the use of a draw bench machine at a speed of 0.5 m min-1. Mechanical properties and structure of strengthened and annealed wires for both steels at different levels of relative reduction in cross-section were determined. Strength of the tested materials was determined in the tensile test, while its hardness was measured with the Vickers hardness test method. Fractographic tests were performed using a scanning electron microscope. It was shown that at the beginning of tensile test, the investigated high manganese steels were characterized by very high plasticity and become stronger as the degree of deformation grows. Surfaces of fractures that were created in the areas where the sample was torn were analyzed. These fractures indicate the presence of transcrystalline ductile fractures.

Tomaszewska, A.; Jab?o?ska, M.; Hadasik, E.; Niewielski, G.; Kawalla, R.

2011-05-01

36

Manganese  

MedlinePLUS

... the body, including processing of cholesterol, carbohydrates, and protein. It might also be involved in bone formation. ... the effectiveness of some antibiotics. To avoid this interaction, take manganese supplements at least one hour after ...

37

Aging properties of vanadium-bearing high manganese stainless steel  

SciTech Connect

Strengthening of austenitic ({gamma}) stainless steel is of great interest to utilization for the structural component. Strengthening of the steel is attained by a combination of following mechanisms such as solution strengthening, strengthening by grain size effect, strain hardening, and precipitation hardening. A selection for the strengthening of {gamma} steel is precipitation hardening due to carbides, nitrides, and intermetallic phases, by which both high strength and low permeability of {gamma} steel may be satisfied. Among Mo, Ti, V, and Nb carbides, it is known that vanadium carbide is considered to be potent contributor to hardening because it precipitates finely in the matrix and grow relatively slower. However, carbide precipitation hardening behavior of highly alloyed {gamma} stainless steel has not been much studied. In this paper, hardening behavior of the vanadium added, low permeability {gamma} stainless steel, Fe-Cr-6Ni-10Mn-V-C, was investigated focusing on the microstructural change and compositional aspects.

Haruna, Y. [Sanyo Special Steel Co., Ltd., Himeji (Japan). Technological Research Lab.] [Sanyo Special Steel Co., Ltd., Himeji (Japan). Technological Research Lab.; Yamamoto, A.; Tsubakino, H. [Himeji Inst. of Tech. (Japan). Dept. of Materials Science and Engineering] [Himeji Inst. of Tech. (Japan). Dept. of Materials Science and Engineering

1997-11-01

38

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

NASA Astrophysics Data System (ADS)

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.

Suutala, N.

1982-12-01

39

Structural studies with the use of XRD and Mössbauer spectroscopy of new high Manganese steels  

NASA Astrophysics Data System (ADS)

New high-strength austenitic and austenitic-ferritic manganese steels represent a significant potential in applications for structural components in the automotive and railway industry due to the excellent combination of high mechanical properties and good plasticity. They belong to the group of steels called AHSS (Advanced High Strength Steels) and UHSS (Ultra High Strength Steels). Application of this combination of properties allows a reduction in the weight of vehicles by the use of reduced cross-section components, and thus to reduce fuel consumption. The development and implementation of industrial production of such interesting and promising steel and its use as construction material requires an improvement of their casting properties and susceptibility to deformation in plastic working conditions. In this work, XRD, Transmission Mössbauer Spectroscopy and Conversion Electron Mössbauer Spectroscopy were employed in a study of the new high-manganese steels with a austenite and austenite-ferrite structure. The influence of the plastic deformation parameters on the changes in the structure, distribution of ferrite and disclosure of the presence of carbides was determined. The analysis of phase transformations in various times using CEMS method made possible to reveal their fine details.

Jablonska, Magdalena Barbara

2014-04-01

40

Corrosion of stainless steel piping in a high manganese fresh water  

SciTech Connect

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.

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

41

Low-carbon manganese steels with vanadium carbonitrides  

Microsoft Academic Search

1.Vanadium carbonitride phase in low-carbon steel improves the strength characteristics. The increase in strength due to vanadium carbonitrides depends on the structure in which the carbontride particles precipitate and, consequently, on their dispersity. With precipitation of vanadium carbonitrides in ferrite, i.e., in the upper range of transformation temperatures, the yield strength is 8–10 kg\\/mm2 higher than for the same steel

A. P. Gulyaev; V. N. Nikitin; Ya. M. Akhundov

1974-01-01

42

Surface modifications induced by yttrium implantation on low manganese–carbon steel  

Microsoft Academic Search

Low manganese–carbon steel samples were ion implanted with yttrium. Sample compositions and structures were investigated before and after yttrium implantations to determine the yttrium distribution in the sample. Yttrium implantation effects were characterized using several analytical and structural techniques such as X-ray photoelectron spectroscopy, reflection high energy electron diffraction, X-ray diffraction, glancing angle X-ray diffraction and Rutherford backscattering spectrometry. In

E Caudron; H Buscail; V. A. C Haanapel; Y. P Jacob; M. F Stroosnijder

1999-01-01

43

The microstructure and properties of a quenched and tempered low-carbon-manganese-niobium steel  

Microsoft Academic Search

The effects of rolling parameters (deformation schedule and finishing temperature), cooling rate (direct quench and air cool),\\u000a and heat treatment have been investigated for a low carbon-manganese-niobium steel. Microstructure was characterized by optical\\u000a and transmission electron microscopy, and correlated with tensile and impact properties. The best combination of strength\\u000a and toughness was obtained by controlled rolling low in the austenite

1976-01-01

44

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

Microsoft Academic Search

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

P. R. Mould; J. M. Gray

1972-01-01

45

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

Microsoft Academic Search

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

P. R. Mould; J. M. Gray

1972-01-01

46

The Influence of Temperature-Time Parameter of Welded Joints Thermal Treatment on Strength-Related Characteristics of Chromium-Molybdenum and Low-Alloy Manganese Steels  

Microsoft Academic Search

The article deals with the analysis of the dependence of strength-related characteristics of welded joints from chromium-molybdenum steel (ASTM A335 Grd. P5) and low-alloy manganese steel (S355J2G3 EN10025-2) upon the parameters of heat treatment. Steel mechanical properties after post-weld heat treatment were analyzed. Chromium- molybdenum (Cr - 5 %) steel and structural low-alloy manganese steel (Mn - 1.4 %) was

Algirdas Vaclovas VALIULIS

2007-01-01

47

Corrosion-induced release of the main alloying constituents of manganese-chromium stainless steels in different media.  

PubMed

The main focus of this paper is the assessment of release rates of chromium, nickel, iron and manganese from manganese-chromium stainless steel grades of low nickel content. The manganese content varied between 9.7 and 1.5 wt% and the corresponding nickel content between 1 and 5 wt%. All grades were exposed to artificial rain and two were immersed in a synthetic body fluid of similar pH but of different composition and exposure conditions. Surface compositional studies were performed using X-ray photoelectron spectroscopy (XPS) in parallel to correlate the metal release process with changes in surface oxide properties. All grades, independent of media, revealed a time-dependent metal release process with a preferential low release of iron and manganese compared to nickel and chromium while the chromium content of the surface oxide increased slightly. Manganese was detected in the surface oxide of all grades, except the grade of the lowest manganese bulk content. No nickel was observed in the outermost surface oxide. Stainless steel grades of the lowest chromium content (approximately 16 wt%) and highest manganese content (approximately 7-9 wt%), released the highest quantity of alloy constituents in total, and vice versa. No correlation was observed between the release rate of manganese and the alloy composition. Released main alloy constituents were neither proportional to the bulk alloy composition nor to the surface oxide composition. PMID:18728902

Herting, Gunilla; Wallinder, Inger Odnevall; Leygraf, Christofer

2008-09-01

48

Manganese-stabilized austenitic stainless steels for fusion applications  

DOEpatents

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.

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

1990-01-01

49

The Behavior of Precipitates during Hot-Deformation of Low-Manganese, Titanium-Added Pipeline Steels  

Microsoft Academic Search

The behavior of manganese and titanium sulfides during the hot deformation of a low-carbon, low-manganese, titanium-added\\u000a steel has been studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive\\u000a spectrometry (EDS) analysis. In addition, the effects of deformation temperature and strain rate on the size and distribution\\u000a of precipitates have been studied using an automatic inclusion analysis system.

Ali Dehghan-Manshadi; Rian J. Dippenaar

2010-01-01

50

Influence of Aluminum Alloying and Heating Rate on Austenite Formation in Low Carbon-Manganese Steels  

Microsoft Academic Search

This investigation focuses on the austenite formation process during continuous heating, over a wide range of heating rates\\u000a (0.05 to 20 K\\/s), in three low carbon-manganese steels alloyed with different levels of aluminum (0.02, 0.48, and 0.94, wt pct\\u000a Al). High resolution dilatometry, combined with metallographic observations, was used to determine the starting (Ac\\u000a 1) and finishing (Ac\\u000a 3) temperatures of this

D. San Martín; Y. Palizdar; C. García-Mateo; R. C. Cochrane; R. Brydson; A. J. Scott

2011-01-01

51

Ennoblement of Stainless Steel by the Manganese-Depositing Bacterium Leptothrix discophora  

PubMed Central

The noble shift in open-circuit potential exhibited by microbially colonized stainless steel (ennoblement) was investigated by examining the relationship among surface colonization, manganese deposition, and open-circuit potential for stainless steel coupons exposed to batch cultures of the manganese-depositing bacterium Leptothrix discophora. Open-circuit potential shifted from -100 to +330 mV(infSCE) as a biofilm containing 75 nmol of MnO(infx) cm(sup-2) formed on the coupon surface but changed little further with continued MnO(infx) deposition up to 270 nmol cm(sup-2). Increased open-circuit potential corresponded to decreasing Mn(II) concentration in solution and to increased MnO(infx) accumulation and attached cell density on the coupon surfaces. MnO(infx) deposition was attributable to biological activity, and Mn(II) was observed to enhance cell attachment. The experimental results support a mechanism of ennoblement in which open-circuit potential is fixed near +350 mV(infSCE) by the cathodic activity of biomineralized MnO(infx). PMID:16535635

Dickinson, W. H.; Caccavo, F.; Olesen, B.; Lewandowski, Z.

1997-01-01

52

Ennoblement of Stainless Steel by the Manganese-Depositing Bacterium Leptothrix discophora.  

PubMed

The noble shift in open-circuit potential exhibited by microbially colonized stainless steel (ennoblement) was investigated by examining the relationship among surface colonization, manganese deposition, and open-circuit potential for stainless steel coupons exposed to batch cultures of the manganese-depositing bacterium Leptothrix discophora. Open-circuit potential shifted from -100 to +330 mV(infSCE) as a biofilm containing 75 nmol of MnO(infx) cm(sup-2) formed on the coupon surface but changed little further with continued MnO(infx) deposition up to 270 nmol cm(sup-2). Increased open-circuit potential corresponded to decreasing Mn(II) concentration in solution and to increased MnO(infx) accumulation and attached cell density on the coupon surfaces. MnO(infx) deposition was attributable to biological activity, and Mn(II) was observed to enhance cell attachment. The experimental results support a mechanism of ennoblement in which open-circuit potential is fixed near +350 mV(infSCE) by the cathodic activity of biomineralized MnO(infx). PMID:16535635

Dickinson, W H; Caccavo, F; Olesen, B; Lewandowski, Z

1997-07-01

53

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

54

Dilatometric characterization of pearlite dissolution in 0.1C-0.5Mn low carbon low manganese steel  

Microsoft Academic Search

Very little information is available about the austenite formation in steels subjected to continuous heating. In the present work, high-resolution dilatometry was used to study the dissolution of pearlite during continuous heating austenitization in a low-carbon low-manganese steel with a ferrite-pearlite starting microstructure. A clear differentiation between pearlite dissolution process and α â γ transformation has been found in this

C. Garc??a de Andrés; F. G. Caballero; C. Capdevila

1998-01-01

55

Manganese distribution in brains of Sprague-Dawley rats after 60 days of stainless steel welding-fume exposure.  

PubMed

Welders working in a confined space, as in the shipbuilding industry, are at risk of being exposed to high concentrations of welding fumes and developing pneumoconiosis or other welding-fume exposure related diseases. Among such diseases, manganism resulting from welding-fume exposure remains a controversial issue, as the movement of manganese into specific brain regions has not yet been clearly established. Accordingly, to investigate the distribution of manganese in the brain after welding-fume exposure, male Sprague-Dawley rats were exposed to welding fumes generated from manual metal arc-stainless steel (MMA-SS) at concentrations of 63.6 +/- 4.1 mg/m(3) (low dose, containing 1.6 mg/m(3) Mn) and 107.1 +/- 6.3 mg/m(3) (high dose, containing 3.5 mg/m(3) Mn) total suspended particulate (TSP) for 2 h per day in an inhalation chamber over a 60-day period. Blood, brain, lung, and liver samples were collected after 2 h, 15, 30, and 60 days of exposure and the tissues analyzed for their manganese concentrations using an atomic absorption spectrophotometer. Although dose- and time-dependent increases in the manganese concentrations were found in the lungs and livers of the rats exposed for 60 days, only slight manganese increases were observed in the blood during this period. Major statistically significant increases in the brain manganese concentrations were detected in the cerebellum after 15 days of exposure and up until 60 days. Slight increases in the manganese concentrations were also found in the substantia nigra, basal ganglia (caudate nucleus, putamen, and globus pallidus), temporal cortex, and frontal cortex, thereby indicating that the pharmacokinetics and distribution of the manganese inhaled from the welding fumes were different from those resulting from manganese-only exposure. PMID:14637372

Yu, Il Je; Park, Jung Duck; Park, Eon Sub; Song, Kyung Seuk; Han, Kuy Tae; Han, Jeong Hee; Chung, Yong Hyun; Choi, Byung Sun; Chung, Kyu Hyuck; Cho, Myung Haing

2003-12-01

56

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

57

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

SciTech Connect

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.

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

58

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

SciTech Connect

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.

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

59

Levels of Arsenic, Cadmium, Lead, Manganese and Zinc in Biological Samples of Paralysed Steel Mill Workers with Related to Controls  

Microsoft Academic Search

The determination of essential trace and toxic elements in the biological samples of human beings is an important clinical\\u000a screening procedure. This study aimed to assess the possible effects of environmental exposure on paralysed male workers (n?=?75) belonging to the production and quality control departments of a steel mill. In this investigation, the concentrations\\u000a of arsenic, cadmium, lead, manganese and

Hassan Imran Afridi; Tasneem Gul Kazi; Atif G. Kazi; Faheem Shah; Sham Kumar Wadhwa; Nida Fatima Kolachi; Abdul Qadir Shah; Jameel Ahmed Baig; Naveed Kazi

60

Applicability of ultrasonic technique for evaluation of elastic plastic fracture toughness of high manganese steel at low temperatures  

Microsoft Academic Search

A study on the evaluation of elastic-plastic fracture toughness, JIC, by ultrasonic technique is described for a newly developed high manganese steel at low temperature. In order to see the\\u000a applicability of the ultrasonic technique based on pulse echo method at low temperature, special attention was paid to detect\\u000a change point of ultrasonic echo due to the onset of stable

Joon-Hyun Lee

1995-01-01

61

Effect of impact energy on the impact-wear properties of low carbon high manganese alloy steels in corrosive conditions  

Microsoft Academic Search

The impact-wear properties of low carbon high manganese alloy steel were tested under three different impact energies (0.7\\u000a J, 1.2 J and 1.7 J) using a modified MLD-10 wear tester. SEM inspection of the wear surface and subsurface optical metallographic\\u000a analysis reveal the impact wear mechanism. Under corrosive conditions we observe a shift from single micro-cutting to impact-flaking,\\u000a after the

Kai Wang; Xiao-Dong Du; Kuk-Tae Youn; Yasunori Hayashi; Chan Gyu Lee; Bon Heun Koo

2008-01-01

62

TiC precipitation induced effect on microstructure and mechanical properties in low carbon medium manganese steel  

Microsoft Academic Search

The precipitation behavior of titanium treated by different processes and its effect on microstructure and mechanical properties has been investigated in low carbon medium manganese steel. It is found that the formed precipitates during both tempering and reheating-quenching processes are TiCs. The size of them mainly ranges from 1 to 18nm and 1 to 36nm, respectively. And tempering treatment especially

Y. Han; J. Shi; L. Xu; W. Q. Cao; H. Dong

63

Surface composition of the steel powders pre-alloyed with manganese  

NASA Astrophysics Data System (ADS)

The determination of the surface oxide layer composition is vital to facilitate the adjustment of the sintering conditions for sufficient removal of the surface oxides for providing strong metal bonding between the metal particles during sintering. To systematically investigate the composition, morphology and thickness of the surface oxide the influence of manganese content from 0.3 to 1.8 wt.% on the surface products composition in the case of water atomized steel powder was evaluated. Analysis of the powder surfaces by X-ray photoelectron spectroscopy and high-resolution scanning electron microscopy in combination with X-ray microanalysis showed that powder particles in all cases are covered by heterogeneous oxide layer, composed of particulate features of thermodynamically stable oxides (Cr-Mn-Si) and homogeneous iron surface oxide layer in between. For increasing alloying content the fraction of stable oxide cations in the surface layer increases linearly, whereas the thickness of the iron oxide layer decreases. Moreover, from the investigation of the sintering and degassing behavior by thermal analysis coupled with mass-spectrometry (TG/DTA + MS), three different stages of carbothermal reduction process were observed and their correlation with surface oxides composition was established during sintering in argon.

Hryha, E.; Gierl, C.; Nyborg, L.; Danninger, H.; Dudrova, E.

2010-04-01

64

Dynamic recrystallization and precipitation in high manganese austenitic stainless steel during hot compression  

NASA Astrophysics Data System (ADS)

Dynamic recrystallization and precipitation in a high manganese austenitic stainless steel were investigated by hot compression tests over temperatures of 950-1150°C at strain rates of 0.001 s-1-1 s-1. All the flow curves within the studied deformation regimes were typical of dynamic recrystallization. A window was constructed to determine the value of apparent activation energy as a function of strain rate and deformation temperature. The kinetics of dynamic recrystallization was analyzed using the Avrami kinetics equation. A range of apparent activation energy for hot deformation from 303 kJ/mol to 477 kJ/mol is obtained at different deformation regimes. Microscopic characterization confirms that under a certain deformation condition (medium Zener-Hollomon parameter ( Z) values), dynamic recrystallization appears at first, but large particles can not inhibit the recrystallization. At low or high Z values, dynamic recrystallization may occur before dynamic precipitation and proceeds faster. In both cases, secondary phase precipitation is observed along prior austenite grain boundaries. Stress relaxation tests at the same deformation temperatures also confirm the possibility of dynamic precipitation. Unexpectedly, the Avrami's exponent value increases with the increase of Z value. It is associated with the priority of dynamic recrystallization to dynamic precipitation at higher Z values.

Momeni, Amir; Kazemi, Shahab; Ebrahimi, Golam; Maldar, Alireza

2014-01-01

65

Manganese exposure in steel smelters a health hazard to the nervous system.  

PubMed

In a study of the effects of low-level exposure to manganese (0.19-1.39 mg/m3 for 1-45 years) 30 men (aged 20-64 years) from two steel smelting works and 60 unexposed referents (aged 22-65 years) were examined with the use of a general health inquiry, electroencephalography, event-related auditory evoked potentials, brain-stem auditory evoked potentials, diadochokinesometry, simple and complex reaction time, finger tapping, digit span, mental arithmetic, vocabulary, a coding task, manual dexterity, symptoms, and mood scales, the diagnostic interview scheme, a dynamic rating scale for neurasthenic syndrome, and a comprehensive psychopathological rating scale. No group differences were found in the electroencephalography or the psychiatric examinations. However, there were increased frequencies of some symptoms, the diadochokinesis was slower, the P-300 latency and reaction time were increased, and finger-tapping and digit-span performance were impaired in the exposed group. These effects were interpreted as early (subclinical) signs of disturbances of the same type as parkinsonism. PMID:1925437

Wennberg, A; Iregren, A; Struwe, G; Cizinsky, G; Hagman, M; Johansson, L

1991-08-01

66

Elevated airborne exposures of teenagers to manganese, chromium, and iron from steel dust and New York City's subway system.  

PubMed

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

Chillrud, Steven N; Epstein, David; Ross, James M; Sax, Sonja N; Pederson, Dee; Spengler, John D; Kinney, Patrick L

2004-02-01

67

Effect of sulfur on rolling contact fatigue life of high-manganese precipitation-hardening austenitic steel  

SciTech Connect

For mechanical components used in high magnetic flux such as bearings and shafts that undergo cyclic stress, materials require low permeability with high strength, hardness, appropriate machinability, and good fatigue properties. Although it is implied that low permeability and machinability will be achieved by a selection of sulfurized austenitic ({gamma}) steel grades, effect of manganese sulfide (MnS) on fatigue properties of such grades especially for bearing applications is not clarified. For high-carbon chromium bearing steels, the effect of MnS on rolling contact fatigue life of the steels containing sulfur less than 0.03% are discussed. In these studies, the effect of MnS is not clearly determined whether it is beneficial or harmful to contact fatigue lives of the steels. However, effect of MnS under higher sulfur content, i.e., 0.10%, on the fatigue properties of {gamma} steel has not been studied. In this paper, the effect of sulfur on rolling contact fatigue properties of vanadium added {gamma} steel, 10Cr-6Ni-8Mn-1.6V-0.6C, was investigated focusing on microstructural change in connection with MnS particles.

Haruna, Y. [Sanyo Special Steel Co., Ltd., Himeji (Japan). Technological Research Lab.] [Sanyo Special Steel Co., Ltd., Himeji (Japan). Technological Research Lab.; Yamamoto, A.; Tsubakino, H. [Himeji Inst. of Tech. (Japan)] [Himeji Inst. of Tech. (Japan)

1998-10-05

68

Influence of Al on the Microstructural Evolution and Mechanical Behavior of Low-Carbon, Manganese Transformation-Induced-Plasticity Steel  

Microsoft Academic Search

Microstructural design with an Al addition is suggested for low-carbon, manganese transformation-induced-plasticity (Mn TRIP)\\u000a steel for application in the continuous-annealing process. With an Al content of 1 mass pct, the competition between the recrystallization\\u000a of the cold-rolled microstructure and the austenite formation cannot be avoided during intercritical annealing, and the recrystallization\\u000a of the deformed matrix does not proceed effectively. The addition of

Dong-Woo Suh; Seong-Jun Park; Tae-Ho Lee; Chang-Seok Oh; Sung-Joon Kim

2010-01-01

69

Effects of annealing conditions on microstructure and mechanical properties of low carbon, manganese transformation-induced plasticity steel  

Microsoft Academic Search

The effects of annealing conditions on microstructural evolution and mechanical properties have been investigated in low carbon,\\u000a manganese TRIP (Mn TRIP) steel based on a 0.12C-6Mn-0.5Si-3Al alloy system. The microstructure of cold-rolled sheet subjected\\u000a to annealing at 760 °C to 800 °C for 30 s to 1800 s consists of a recrystallized ferrite matrix and fine-grained austenite\\u000a with a phase

Jae-Myeong Jang; Sung-Joon Kim; Nam Hyun Kang; Kyung-Mox Cho; Dong-Woo Suh

2009-01-01

70

Manganese-Cobalt Mixed Spinel Oxides as Surface Modifiers for Stainless Steel Interconnects of Solid Oxide Fuel Cells  

SciTech Connect

Ferritic stainless steels are promising candidates for interconnect applications in low- and mid-temperature solid oxide fuel cells (SOFCs). A couple of issues however remain for the particular application, including the chromium poisoning due to chromia evaporation, and long-term surface and electrical stability of the scale grown on these steels. Application of a manganese colbaltite spinel protection layer on the steels appears to be an effective approach to solve the issues. For an optimized performance, Mn{sub 1+x}Co{sub 2-x}O{sub 4} (-1 {le} x {le} 2) spinels were investigated against properties relative for protection coating applications on ferritic SOFC interconnects. Overall it appears that the spinels with x around 0.5 demonstrate a good CTE match to ceramic cell components, a relative high electrical conductivity, and a good thermal stability up to 1,250 C. This was confirmed by a long-term test on the Mn{sub 1.5}Co{sub 1.5}O{sub 4} protection layer that was thermally grown on Crofer22 APU, indicating the spinel protection layer not only significantly decreased the contact resistance between a LSF cathode and the stainless steel interconnects, but also inhibited the sub-scale growth on the stainless steels.

Xia, Gordon; Yang, Z Gary; Stevenson, Jeffry W.

2006-11-06

71

TEM characterization of precipitates in the segregated regions of a low-carbon, low-manganese, titanium-added steel.  

PubMed

A concentric solidification technique has been employed to simulate sulphide precipitation at the centreline of a continuously cast low-carbon, low-manganese, titanium-added steel slab. Selected precipitates were identified using transmission electron microscopy following sample preparation by focused ion beam milling techniques. FeTiS(2) and hexagonal MnS containing iron atoms form in close proximity to each other in super-saturated areas of the concentrically solidified sample. The presence of FeTiS(2) precipitates in low-carbon steel has been verified for the first time, and the crystal structure determined by electron diffraction analysis as a trigonal CdI(2)-type with a P3 m1 space group and lattice parameters of a= 0.341 nm and c= 0.569 nm. PMID:17845704

Aminorroaya, Sima; Dippenaar, Rian

2007-08-01

72

Influence of Al on the Microstructural Evolution and Mechanical Behavior of Low-Carbon, Manganese Transformation-Induced-Plasticity Steel  

NASA Astrophysics Data System (ADS)

Microstructural design with an Al addition is suggested for low-carbon, manganese transformation-induced-plasticity (Mn TRIP) steel for application in the continuous-annealing process. With an Al content of 1 mass pct, the competition between the recrystallization of the cold-rolled microstructure and the austenite formation cannot be avoided during intercritical annealing, and the recrystallization of the deformed matrix does not proceed effectively. The addition of 3 mass pct Al, however, allows nearly complete recrystallization of the deformed microstructure by providing a dual-phase cold-rolled structure consisting of ferrite and martensite and by suppressing excessive austenite formation at a higher annealing temperature. An optimized annealing condition results in the room-temperature stability of the intercritical austenite in Mn TRIP steel containing 3 mass pct Al, permitting persistent transformation to martensite during tensile deformation. The alloy presents an excellent strength-ductility balance combining a tensile strength of approximately 1 GPa with a total elongation over 25 pct, which is comparable to that of Mn TRIP steel subjected to batch-type annealing.

Suh, Dong-Woo; Park, Seong-Jun; Lee, Tae-Ho; Oh, Chang-Seok; Kim, Sung-Joon

2010-02-01

73

Monitoring of occupational exposure in manufacturing of stainless steel constructions. Part I: Chromium, iron, manganese, molybdenum, nickel and vanadium in the workplace air of stainless steel welders.  

PubMed

Exposure to workplace airborne pollutants was examined in a group of 20 workers dealing mainly with welding, polishing, drilling and assembling of stainless steel constructions. Airborne particulate matter (APM) collected using both personal and stationary samplers was analyzed by instrumental neutron activation analysis (INAA). Quality assurance procedures of both sampling and analytical stages are described. Of the elements determined, results are presented for chromium, iron, manganese, molybdenum, nickel and vanadium. The median values of element concentrations exceeded the maximum admissible limits for workplace pollutants only for chromium, while for nickel the limit was exceeded in several individual cases. Sampling of hair, nails, blood, urine and saliva to be used for biological monitoring of the exposed and control groups is also described. PMID:11787242

Kucera, J; Bencko, V; Pápayová, A; Saligová, D; Tejral, J; Borská, L

2001-11-01

74

Mild steels coated with 14% manganese covered electrodes (E7-UM-200-K and E1-UM-350): Phenomena at the steel-coating interface  

SciTech Connect

In this work the authors have studied the phenomena in the interface of the coating made on soft carbon steel with electrodes with a high content of manganese. The study has been done with scanning electron microscope and X-rays mapping images. These images show how the alloy elements are distributed in each of the constituent elements presented in the interface, and the nature of these constituents. These results have allowed us to verify that many of the problems that arise in homogeneous joints, as such localised corrosion, low interface resistance, etc., happened, precisely in these regions. As a help to determine the nature of the constituent elements, microhardness measurements have also been made.

Molleda, F. [Escuela Tecnica Superior de Ingenieros Navales de Madrid (UPM) (Spain)]. E-mail: fmolleda@etsin.upm.es; Mora, J. [Escuela Tecnica Superior de Ingenieros Navales de Madrid (UPM) (Spain); Molleda, F.J. [ESAB Iberica (Spain); Carrillo, E. [Escuela Tecnica Superior de Ingenieros Navales de Madrid (UPM) (Spain); Mora, E. [Escuela Tecnica Superior de Ingenieros Navales de Madrid (UPM) (Spain); Mellor, B.G. [University of Southampton (United Kingdom)

2006-12-15

75

Electron spectroscopy for chemical analysis study of corrosion films formed on manganese stainless steels  

SciTech Connect

Films formed on two grades of Mn stainless steels in 1 M hydrochloric acid (HCl) freely exposed to air at different potentials were examined using electron spectroscopy for chemical analysis (ESCA). The Cr content of the film, which is related closely to corrosion resistance of the base alloys, was lower within the films formed on Mn stainless steels as compared to a normal type 304 (UNS S30400) stainless steels. The film also contained significant amounts of Mn, Ni, and Cu. It was proposed that the presence o higher amounts of Mn, an electrochemically active element, with Cu resulted in poor passivation behavior of the present high Mn stainless steels.

Raja, V.S.; Devasenapathi, A.; Veluchamy, P.; Minoura, H.

1999-12-01

76

Controlling the composition of nonmetallic inclusions in a low-alloy manganese steel  

Microsoft Academic Search

At the modern level of out-furnace treatment of steel, the steel composition becomes a substantial factor that determines the degree of influence of oxide particles on its properties. Therefore, the development of a method for controlling the inclusion composition is a challenging and technologically feasible problem. In this work, we study the possibility of controlling the composition of nonmetallic inclusions

A. V. Dub; A. N. Romashkin; Yu. V. Gordeev; G. G. Shvetsov; I. V. Zinkovskii

2009-01-01

77

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

NASA Astrophysics Data System (ADS)

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.

Akbari, Alireza; Mohammadzadeh, Roghayeh

2015-01-01

78

High Manganese and Aluminum Steels for the Military and Transportation Industry  

NASA Astrophysics Data System (ADS)

Lightweight advanced high strength steels (AHSS) with aluminum contents between 4 and 12 weight percent have been the subject of intense interest in the last decade because of an excellent combination of high strain rate toughness coupled with up to a 17% reduction in density. Fully austenitic cast steels with a nominal composition of Fe-30%Mn-9%Al-0.9%C are almost 15% less dense than quenched and tempered Cr-Mo steels (SAE 4130) with equivalent strengths and dynamic fracture toughness. This article serves as a review of the tensile and high-strain-rate fracture properties associated mainly with silicon additions to this base composition. In the solution-treated condition, cast steels have high work-hardening rates with elongations up to 64%, room-temperature Charpy V-notch (CVN) impact energies up to 200 J, and dynamic fracture toughness over 700 kJ/m2. Silicon additions in the range of 0.59-1.56% Si have no significant effect on the mechanical properties of solution-treated steels but increased the tensile strength and hardness during aging. For steels aged at 530°C to an average hardness of 310 Brinell hardness number, HBW, increasing the amount of silicon from 1.07% to 1.56% decreased the room temperature CVN breaking energy from 92 J to 68 J and the dynamic fracture toughness from 376 kJ/m2 to 265 kJ/m2. Notch toughness is a strong function of phosphorus content, decreasing the solution-treated CVN impact toughness from 200 J in a 0.006% P steel to 28 J in a 0.07% P steel. For age-hardened steels with 1% Si, increasing levels of phosphorus from 0.001% to 0.043% decreased the dynamic fracture toughness from 376 kJ/m2 to 100 kJ/m2.

Bartlett, Laura; Van Aken, David

2014-09-01

79

Brittle fracture resistance of manganese-silicon low-carbon steels with layered-banded structure  

Microsoft Academic Search

Structural sheet steels 08GNB, 06GNB (F40W), and 09KhMN2D and steel 09G2B imported from Germany are studied. The effect of\\u000a the layered-banded structure on the anisotropy of the resistance of the steels to brittle fracture is determined using the\\u000a results of tests of impact specimens cut in different directions with respect to that of rolling. The critical brittle point\\u000a (CBT) is

V. I. Gorynin

2009-01-01

80

Effect of arsenic on the susceptibility of low-carbon manganese steel to reversible temper brittleness  

Microsoft Academic Search

1.The presence of 0.155% As in 09G2 steel considerably increases the susceptibility to temper brittleness. The temperature of the threshold of cold brittleness is 110°C higher in quenched and slowly cooled samples than in rapidly cooled samples.2.An increase of the phosphorus content from 0.02 to 0.04% in the steel containing 0.15% As has no effect either on the absolute value

Yu. S. Tomenko; I. V. Navrotskii; I. N. Dryukova

1966-01-01

81

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

NASA Astrophysics Data System (ADS)

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.

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

82

Nanocrystallization and ? martensite formation in the surface layer of medium-manganese austenitic wear-resistant steel caused by shot peening  

Microsoft Academic Search

The nanocrystallization and ? martensite formation in the surface layer of medium-manganese austenitic wear-resistant steel subjected to high-energy shot peening treatment were investigated by X-ray diffraction and transmission electron microscopy. The results show that nanograined microstructure mainly composed of strain-induced ? martensite grains with the average size of ?8nm were produced in the shot-peened surface. However, any induced phases are

T. S. Wang; B. Lu; M. Zhang; R. J. Hou; F. C. Zhang

2007-01-01

83

In-situ X-ray diffraction study of the behaviour of yttrium implanted low manganese-carbon steel at high temperature  

Microsoft Academic Search

Yttrium implanted and unimplanted low manganese-carbon steel samples were analysed at T=700°C and under oxygen partial pressure (Po2=0.04 Pa) for 24 h to show the yttrium implantation effect on sample oxidation resistance at high temperature. Weight gains resulting from sample oxidation were studied by thermogravimetry and structural analyses were performed by in-situ high temperature X-ray diffraction under the same experimental

E Caudron; H Buscail; R Cueff

2000-01-01

84

Evolution of Nickel-Manganese-Silicon Dominated Phases in Highly Irradiated Reactor Pressure Vessel Steels  

SciTech Connect

Formation of a high density of Ni-Mn-Si nm-scale precipitates in irradiated reactor pressure vessel steels, both with and without Cu, could lead to severe embrittlement. Models long ago predicted that these precipitates, which are not treated in current embrittlement regulations, would emerge only at high fluence. However, the mechanisms and variables that control Ni-Mn- Si precipitate formation, and their detailed characteristics, have not been well understood. High flux irradiations of six steels with systematic variations in Cu and Ni were carried out at ˜ 295±5°C to high and very high neutron fluences of ˜ 1.3x1020 and 1.1x1021 n/cm2. Atom probe tomography (APT) shows that significant mole fractions of these precipitates form in the Cu bearing steels at ˜ 1.3x1020 n/cm2, while they are only beginning to develop in Cu-free steels. However, large mole fractions, far in excess of those found in previous studies, are observed at 1.1x1021 n/cm2 at all Cu levels. The precipitates diffract, and in one case are compositionally and structurally consistent with the Mn6Ni16Si7 G-phase. At the highest fluence, the large precipitate mole fractions primarily depend on the steel Ni content, rather than Cu, and lead to enormous strength increases up to about 700 MPa. The implications of these results to light water reactor life extension are discussed briefly.

Peter B Wells; Yuan Wu; Tim Milot; G. Robert Odette; Takuya Yamamoto; Brandon Miller; James Cole

2014-11-01

85

Effects of deoxidizing degree on the pitting corrosion behavior of carbon and manganese steels  

NASA Astrophysics Data System (ADS)

Nine steels with different deoxidizing degrees and two comparative steels were selected. Their pitting initiation susceptibility was compared by means of potentiodynamic polarization tests in 3wt% NaCl solution. The pit propagation rate was evaluated in artificial sea water and 3wt% sea salt solution by simulating occluded corrosion cell (SOCC) test and hanging plate test, respectively. The composition of inclusions and corrosive feature were studied by scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), and optical microscopy (OM). The results indicate that sulfide inclusions in steel are the sites for pit nucleation. The sulphide inclusions vary in shape from short spindle-like to long strip-like with increasing deoxidizing degree. Under the same conditions, the lower the deoxidizing degree gets, the lower the pitting initiation susceptibility becomes, and the stronger the resistance to pit propagation exhibits. For steels with different deoxidizing degrees, their pitting initiation susceptibility is mainly influenced by thermodynamic stability, while the pit propagation rate is primarily subject to the characteristics of inclusions in steel.

Cao, Guo-Liang; Li, Guo-Min; Chen, Shan; Chang, Wan-Shun; Chen, Xue-Qun

2011-04-01

86

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

NASA Astrophysics Data System (ADS)

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.

Buckholz, Samuel August

87

Carbon determination in carbon-manganese steels under atmospheric conditions by Laser-Induced Breakdown Spectroscopy.  

PubMed

The most sensitive lines of carbon, used nowadays for its determination in steels by laser-induced-breakdown spectroscopy (LIBS), are at vacuum UV and, thereby, LIBS potential is significantly reduced. We suggested the use of the C I 833.51 nm line for carbon determination in low-alloy steels (c(C)~0.186-1.33 wt.%) in air. Double-pulse LIBS with the collinear scheme was performed for maximal enhancement of a carbon emission signal without substantial complication of experimental setup. Since this line is strongly broadened in laser plasma, it overlapped with the closest iron lines greatly. We implemented a PCR method for the construction of a multivariate calibration model under spectral interferences. The model provided a RMSECV = 0.045 wt.%. The predicted carbon content in the rail templet was in an agreement with the reference value obtained by a combustion analyzer within the relative error of 6%. PMID:25321709

Labutin, Timur A; Zaytsev, Sergey M; Popov, Andrey M; Zorov, Nikita B

2014-09-22

88

Inclusions nucleating intragranular polygonal ferrite and acicular ferrite in low alloyed carbon manganese steel welds  

Microsoft Academic Search

The inclusion-assisted formation of two types of intragranular ferrite in low alloyed C-Mn steel welds, intragranular polygonal\\u000a ferrite (IPF) and acicular ferrite (IAF), was investigated in relation to the inclusion characteristics (mainly size and chemistry)\\u000a and the welding heat input. For this analysis, inclusions engulfed by one ferrite grain and those shared by two ferrite grains\\u000a were considered as the

Kyung-Tae Park; Si Woo Hwang; Jung Hoon Ji; Chang Hee Lee

2011-01-01

89

Changes in blood manganese concentration and MRI t1 relaxation time during 180 days of stainless steel welding-fume exposure in cynomolgus monkeys.  

PubMed

Welders are at risk of being exposed to high concentrations of welding fumes and developing pneumoconiosis or other welding-fume exposure-related diseases. Among such diseases, manganism resulting from welding-fume exposure remains a controversial issue, as although the movement of manganese into specific brain regions has been established, the similar movement of manganese presented with other metals, such as welding fumes, has not been clearly demonstrated as being similar to that of manganese alone. Meanwhile, the competition between Mn and iron for iron transporters, such as transferrin and DMT-1, to the brain has also been implicated in the welding-fume exposure. Thus, the increased signal intensities in the basal ganglia, including the globus pallidus and subcortical frontal white matter, based on T1-weighted magnetic resonances in welders, require further examination as regards the correspondence with an increased manganese concentration. Accordingly, to investigate the movement of manganese after welding-fume exposure, 6 cynomolgus monkeys were acclimated for 1 mo and assigned to 3 dose groups: unexposed, low dose of (total suspended particulate [TSP] 31 mg/m3, 0.9 mg/m3 of Mn), and high dose of total suspended particulate (62 mg/m3 TSP, 1.95 mg/m3 of Mn). The primates were exposed to manual metal-arc stainless steel (MMA-SS) welding fumes for 2 h/day in an inhalation chamber system equipped with an automatic fume generator for 6 mo. Magnetic resonance imaging (MRI) studies of the basal ganglia were conducted before the initiation of exposure and thereafter every month. During the exposure, the blood chemistry was monitored every 2 wk and the concentrations of metal components in the blood were measured every 2 wk and compared with ambient manganese concentrations. The manganese concentrations in the blood did not show any significant increase until after 2 mo of exposure, and then reached a plateau after 90 days of exposure, showing that an exposure period of at least 60 days was required to build up the blood Mn concentration. Furthermore, as the blood Mn concentration continued to build, a continued decrease in the MRI T1 relaxation time in the basal ganglia was also detected. These data suggested that prolonged inhalation of welding fumes induces a high MRI T1 signal intensity with an elevation of the blood manganese level. The presence of a certain amount of iron or other metals, such as Cr and Ni, in the inhaled welding fumes via inhalation was not found to have a significant effect on the uptake of Mn into the brain or the induction of a high MRI T1 signal intensity. PMID:17127642

Sung, Jae Hyuck; Kim, Choong Yong; Yang, Seoung Oh; Khang, Hyun Soo; Cheong, Hae Kwan; Lee, Jong Seong; Song, Chang-Woo; Park, Jung Duck; Han, Jeong Hee; Chung, Yong Hyun; Choi, Byung Sun; Kwon, Il Hoon; Cho, Myung Haeng; Yu, Il Je

2007-01-01

90

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

PubMed Central

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

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

2011-01-01

91

Control of cryogenic intergranular fracture in high-manganese austenitic steels  

SciTech Connect

The sources of cryogenic intergranular embrittlement in high-Mn austenitic steels and the conditions necessary for its control are examined. It is shown that the high-Mn alloys are inherently susceptible to intergranular embrittlement due to both their low grain boundary cohesion and heterogeneous deformation characteristics. Extrinsic sources of embrittlement which could account for the transition behavior are not observed. An Auger electron spectroscopy (AES) study shows no indication of impurity-segregation-induced embrittlement. No grain boundary precipitation is observed, and austenite stabilization does not ensure ductile fracture. The influence of chemistry modifications on the ductile-to-brittle transition behavior were also examined through additions of N, Cr, and C to binary Fe-31 Mn. Nitrogen additions increase the 77K yield strength at a rate of 2200 MPa per weight percent N, and increase the austenite stability, but also increase the susceptibility of ternary alloys to intergranular fracture. Quaternary Cr additions are effective in increasing the N solubility, and lower the transition temperature. Carbon additions result in complete suppression of intergranular fracture at 77K. Qualitatively significant changes in the deformation heterogeneity with chemistry modifications are not observed. The temper-toughening of Fe-Mn-Cr-N alloys is associated with the grain boundary segregation of boron and the redistribution of N. Both boron and carbon are expected to inhibit intergranular fracture through increases in grain boundary cohesion.

Strum, M.J.

1986-12-01

92

Low-temperature manganese contributions to the elastic constants of face-centred-cubic Fe-Cr-Ni stainless steel  

Microsoft Academic Search

By ultrasonic methods, we determined the elastic constants between 295 and 4 K of nominally Fe-18Cr-8Ni alloys (in wt%) containing up to 6% manganese. We report five elastic constants:C1 = longitudinal modulus,B = bulk modulus,E = Young modulus,G = shear modulus, and v = Poisson ratio. At all temperatures, manganese lowers all these elastic constants. With the exception of v,

H. M. Ledbetter; S. A. Kim

1988-01-01

93

Comparison of high MRI T1 signals with manganese concentration in brains of cynomolgus monkeys after 8 months of stainless steel welding-fume exposure.  

PubMed

Several pharmacokinetic studies on inhalation exposure to manganese (Mn) have already demonstrated that Mn readily accumulates in the olfactory and brain regions. However, a shortening of the magnetic resonance imaging (MRI) T1 relaxation time or high T1 signal intensity in specific sites of the brain, including the globus pallidus and subcortical frontal white matter, as indicative of tissue manganese accumulation has not yet been clearly established for certain durations of known doses of welding-fume exposure in experimental animals. Accordingly, to investigate the movement of manganese after welding-fume exposure, six cynomolgus monkeys were acclimated and assigned to three dose groups: unexposed, low dose (31 mg/m(3) total suspended particulate [TSP], 0.9 mg/m(3) of Mn), and high dose (62 mg/m(3) TSP, 1.95 mg/m(3) of Mn) of total suspended particulate. The primates were exposed to manual metal arc stainless steel (MMA-SS) welding fumes for 2 h per day in an inhalation chamber system equipped with an automatic fume generator. Magnetic resonance imaging (MRI) studies were conducted before the initiation of exposure and thereafter every month. The tissue Mn concentrations were then measured after a plateau was reached regarding the shortening of the MRI T1 relaxation time. A dose-dependent increase in the Mn concentration was found in the lungs, while noticeable increases in the Mn concentrations were found in certain tissues, such as the liver, kidneys, and testes. Slight increases in the Mn concentrations were found in the caudate, putamen, frontal lobe, and substantia nigra, while a dose-dependent noticeable increase was only found in the globus pallidus. Therefore, the present results indicated that a shortening of the MRI T1 relaxation time corresponded well with the Mn concentration in the globus pallidus after prolonged welding-fume exposure. PMID:17849280

Park, Jung Duck; Chung, Yong Hyun; Kim, Choong Yong; Ha, Chang Soo; Yang, Seoung Oh; Khang, Hyun Soo; Yu, In Kyu; Cheong, Hae Kwan; Lee, Jong Seong; Song, Chang-Woo; Kwon, Il Hoon; Han, Jeong Hee; Sung, Jae Hyuck; Heo, Jeong Doo; Choi, Byung Sun; Im, Ruth; Jeong, Jayoung; Yu, Il Je

2007-09-01

94

Effect of Nb on the transformation kinetics of low carbon (manganese) steel during deformation of undercooled austenite  

Microsoft Academic Search

The hot compression tests using Gleeble 1500 were performed by varying the true strain up to 1.6 (80% reduction) in Nb-free and Nb-microalloyed steels. The effect of Nb addition on the transformation kinetics during deformation of undercooled austenite was investigated. It was found that as compared with Nb-free steel, the transformation incubation period of Nb-bearing steel was prolonged and the

Guoan Chen; Wangyue Yang; Shouzhen Guo; Zuqing Sun

2006-01-01

95

Austenitic stainless steel and drill collar  

SciTech Connect

A non-magnetic austenitic stainless steel, and a drill collar fabricated therefrom solely by hot forging, the steel having a 0.2% yield strength of at least 85 ksi in the hot worked condition, high stress corrosion cracking resistance, good ductility, and low magnetic permeability even if cold worked, and consisting essentially of, in weight percent, from 0.12% to 0.20% carbon, 11% to 14% manganese, about 16% to about 19% chromium, 1.5% to 2.7% nickel, 0.30% to 0.45% nitrogen, 0.5% to 1.0% copper, about 0.75% maximum molybdenum, about 0.80% maximum silicon, about 0.04% maximum phosphorus, about 0.025% maximum sulfur, and balance essentially iron, with the carbon:nitrogen ratio not greater than 0.6:1.

Cordea, J. N.; Jasper, J. C.; Sheth, H. V.

1985-03-05

96

Steel dust in the New York City subway system as a source of manganese, chromium, and iron exposures for transit workers.  

PubMed

The United States Clean Air Act Amendments of 1990 reflected increasing concern about potential effects of low-level airborne metal exposure on a wide array of illnesses. Here we summarize results demonstrating that the New York City (NYC) subway system provides an important microenvironment for metal exposures for NYC commuters and subway workers and also describe an ongoing pilot study of NYC transit workers' exposure to steel dust. Results from the TEACH (Toxic Exposure Assessment, a Columbia and Harvard) study in 1999 of 41 high-school students strongly suggest that elevated levels of iron, manganese, and chromium in personal air samples were due to exposure to steel dust in the NYC subway. Airborne concentrations of these three metals associated with fine particulate matter were observed to be more than 100 times greater in the subway environment than in home indoor or outdoor settings in NYC. While there are currently no known health effects at the airborne levels observed in the subway system, the primary aim of the ongoing pilot study is to ascertain whether the levels of these metals in the subway air affect concentrations of these metals or related metabolites in the blood or urine of exposed transit workers, who due to their job activities could plausibly have appreciably higher exposures than typical commuters. The study design involves recruitment of 40 transit workers representing a large range in expected exposures to steel dust, the collection of personal air samples of fine particulate matter, and the collection of blood and urine samples from each monitored transit worker. PMID:15738337

Chillrud, Steven N; Grass, David; Ross, James M; Coulibaly, Drissa; Slavkovich, Vesna; Epstein, David; Sax, Sonja N; Pederson, Dee; Johnson, David; Spengler, John D; Kinney, Patrick L; Simpson, H James; Brandt-Rauf, Paul

2005-03-01

97

Mineral of the month: manganese  

USGS Publications Warehouse

Manganese is one of the most important ferrous metals and one of the few for which the United States is totally dependent on imports. It is a black, brittle element predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production, which together provide the largest market for manganese (about 83 percent). It is also used as an alloy with nonferrous metals such as aluminum and copper. Nonmetallurgical applications of manganese include battery cathodes, soft ferrite magnets used in electronics, micronutrients found in fertilizers and animal feed, water treatment chemicals, and a colorant for bricks and ceramics.

Corathers, Lisa

2005-01-01

98

By Thomas S. Jones Manganese (Mn) is essential to iron and steel production by have been among the larger producers. World production of  

E-print Network

widely used aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature. In price developments, the price for metallurgical-grade manganese ore delivered to U.S. customers stayed the same as that in 1994. Prices increased in the U.S. market for upgraded forms of manganese used

Torgersen, Christian

99

MANGANESE IN NARRAGANSETT BAY  

EPA Science Inventory

Concentrations of dissolved manganese and particulate manganese 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 ...

100

NEW ALLOY STEELS BEAT PROCESS BURGABOOS  

Microsoft Academic Search

A discussion of stainless steel corrosion is presented with an analysis ; of developments in corrosion prevention. Illustrative members of several classes ; of stainless steel including low carbon steels, low nickel high manganese steels, ; and steels stabilized with niobium or niobium and tantulum are described. ; (J.R.D.);

D. B. Roach; A. M. Hall

1958-01-01

101

Low-cycle fatigue of chromium-manganese steel 03Kh13AG19 at low temperatures (293–4.2°K)  

Microsoft Academic Search

Conclusions 1.In the temperature range 293–4.2°K ductility characteristics of steel 03Kh13AG19, determined with short-term rupture tests, cannot clearly define its capacity for unilateral deformation with prolonged cyclic loading.2.A reduction in temperature to 77°K does not make a qualitative change in the nature of deformation and failure for steel 03Kh13AG19. The intensity of directional plastic deformation processes only changes quantitatively; the

1986-01-01

102

Autonomic function in manganese alloy workers  

SciTech Connect

The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a frog shop for gouging, welding, and grinding repair of high manganese railway track and a convenience sample of three mild steel welders with lesser manganese exposure also referred because of cognitive or autonomic symptoms. Frog shop air manganese samples 9.6--10 years before and 1.2--3.4 years after the diagnosis of the index case exceeded 1.0 mg/m{sup 3} in 29% and 0.2 mg/m{sup 3} in 62%. Twenty-four-hour electrocardiographic (Holter) monitoring was used to determine the temporal variability of the heartrate (RR{prime} interval) and the rates of change at low frequency and high frequency. MMPI and MCMI personality assessment and short-term memory, figure copy, controlled oral word association, and symbol digit tests were used.

Barrington, W.W.; Angle, C.R.; Willcockson, N.K.; Padula, M.A. [Univ. of Nebraska Medical Center, Omaha, NE (United States)] [Univ. of Nebraska Medical Center, Omaha, NE (United States); Korn, T.

1998-07-01

103

X-rays from non-magnetic cataclysmic variables  

Microsoft Academic Search

Observations with ROSAT and EUVE of non-magnetic cataclysmic variables are reviewed. Eclipses of the X-rays, outburst lightcurves, pulsation periods, and dependence of X-ray luminosity on inclination all indicate that the X-rays in non-magnetic cataclysmic variables are produced in a small region close to the white dwarf. The X-ray spectra show a hard and a soft component, whose temperatures remain constant

F. Verbunt

1996-01-01

104

Autonomic function in manganese alloy workers.  

PubMed

The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a "frog shop" for gouging, welding, and grinding repair of high manganese railway track and a convenience sample of three mild steel welders with lesser manganese exposure also referred because of cognitive or autonomic symptoms. Frog shop air manganese samples 9.6-10 years before and 1.2-3.4 years after the diagnosis of the index case exceeded 1.0 mg/m3 in 29% and 0.2 mg/m3 in 62%. Twenty-four-hour electrocardiographic (Holter) monitoring was used to determine the temporal variability of the heartrate (RR' interval) and the rates of change at low frequency (0.04-0.15 Hz) and high frequency (0.15-0.40 Hz). MMPI and MCMI personality assessment and short-term memory, figure copy, controlled oral word association, and symbol digit tests were used. The five frog shop workers had abnormal sympathovagal balance with decreased high frequency variability (increased ln LF/ln HF). Seven of the eight workers had symptoms of autonomic dysfunction and significantly decreased heart rate variability (rMSSD) but these did not distinguish the relative exposure. Mood or affect was disturbed in all with associated changes in short-term memory and attention in four of the subjects. There were no significant correlations with serum or urine manganese. Power spectrum analysis of 24-h ambulatory ECG indicating a decrease in parasympathetic high frequency activation of heart rate variability may provide a sensitive index of central autonomic dysfunction reflecting increased exposure to manganese, although the contribution of exposures to solvents and other metals cannot be excluded. Neurotoxicity due to the gouging, welding, and grinding of mild steel and high manganese alloys (11-25%) merits air manganese and neuropsychologic surveillance including autonomic function by Holter monitoring of cardiovagal activation. PMID:9630445

Barrington, W W; Angle, C R; Willcockson, N K; Padula, M A; Korn, T

1998-07-01

105

Chronic manganese intoxication  

SciTech Connect

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.

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

106

Manganese action in brain function  

Microsoft Academic Search

Manganese, an essential trace metal, is supplied to the brain via both the blood–brain and the blood–cerebrospinal fluid barriers. There are some mechanisms in this process and transferrin may be involved in manganese transport into the brain. A large portion of manganese is bound to manganese metalloproteins, especially glutamine synthetase in astrocytes. A portion of manganese probably exists in the

Atsushi Takeda

2003-01-01

107

Manganese laser using manganese chloride as lasant  

NASA Technical Reports Server (NTRS)

A manganese vapor laser utilizing manganese chloride as a lasant has been observed and investigated. Lasing is attained by means of two consecutive electrical discharges. The maximum laser output is obtained at a vapor pressure of about 3 torr, a temperature of 680 C, and a time delay between electrical discharges of 150 microsec. The maximum energy density is 1.3 microjoule per cu cm.

Chen, C. J.

1974-01-01

108

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

109

Induction of oxidative stress and inflammatory cytokines by manganese chloride in cultured T98G cells, human brain glioblastoma cell line  

Microsoft Academic Search

Manganese, an essential trace nutrient in human beings, has been widely used in the steel industry to improve hardness, stiffness, and strength. With the increased applications of manganese compounds, discharge into the environment has rapidly increased and may exert adverse effects on human health. In this study, manganese toxicity was investigated using cultured T98G cells, which are derived from human

Eun-Jung Park

2010-01-01

110

Nurse Outcomes in Magnet® and Non-Magnet Hospitals  

PubMed Central

The important goals of Magnet® hospitals are to create supportive professional nursing care environments. A recently published paper found little difference in work environments between Magnet and non-Magnet hospitals. The aim of this study was to determine whether work environments, staffing, and nurse outcomes differ between Magnet and non-Magnet hospitals. A secondary analysis of data from a 4-state survey of 26,276 nurses in 567 acute care hospitals to evaluate differences in work environments and nurse outcomes in Magnet and non-Magnet hospitals was conducted. Magnet hospitals had significantly better work environments (t = ?5.29, P < .001) and more highly educated nurses (t = ?2.27, P < .001). Magnet hospital nurses were 18% less likely to be dissatisfied with their job (P < .05) and 13% less likely to report high burnout (P < .05). Magnet hospitals have significantly better work environments than non-Magnet hospitals. The better work environments of Magnet hospitals are associated with lower levels of nurse job dissatisfaction and burnout. PMID:21934430

Kelly, Lesly A.; McHugh, Matthew D.; Aiken, Linda H.

2011-01-01

111

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

SciTech Connect

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.

Spooner, S.

1997-11-01

112

Far ultraviolet spectroscopy of (non-magnetic) cataclysmic variables  

Microsoft Academic Search

HST and FUSE have provided high signal-to-noise, high-resolution spectra of a variety of cataclysmic variables and have allowed a detailed characterization of FUV emission sources in both high and low states. Here, I describe how this has advanced our understanding of non-magnetic CVs. In the high state, the FUV spectra are dominated by disk emission that is modified by scattering

Knox S. Long; Boris T. Gansicke; Klaus Beuermann; D. de Martino; E. M. Sion; P. Szkody

2006-01-01

113

Quantum Confinement and Non-Magnetic-Doped Dilute Magnetic Semiconductors  

Microsoft Academic Search

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

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

2008-01-01

114

Robustness against non-magnetic impurities in topological superconductors  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

115

The effect of manganese additions on the reactive evaporation of chromium in Ni–Cr alloys  

SciTech Connect

Chromium is used as an alloy addition in stainless steels and nickel-chromium alloys to form protective chromium oxide scales. Chromium oxide undergoes reactive evaporation in high temperature exposures in the presence of oxygen and/or water vapor. The deposition of gaseous chromium species onto solid oxide fuel cell electrodes can reduce the efficiency of the fuel cell. Manganese additions to the alloy can reduce the activity of chromium in the oxide, either from solid solution replacement of chromium with manganese (at low levels of manganese) or from the formation of manganese-chromium spinels (at high levels of manganese). This reduction in chromium activity leads to a predicted reduction in chromium evaporation by as much as a factor of 35 at 800 °C and 55 at 700 °C. Quantifying the effects of manganese additions on chromium evaporation should aid alloy development of metallic interconnects and balance-of-plant alloys.

Holcomb, G.R.; Alman, D.E.

2006-05-01

116

Assessment of the manganese content of the drinking water source in Yancheng, China.  

PubMed

Excessive intake of manganese can damage the nervous system of the human body. In August 2009, the manganese content of the drinking water source in Yancheng exceeded the national standard of drinking water source, which influenced the daily life of the local residents. The aim of this study was to investigate the factors leading to the manganese content of river water in Yancheng exceeding the national standard. To the data, the manganese content of surface water in Yancheng already met the national standard of drinking water source in September 2009, but the manganese content of river sediment was relatively high, especially in Mangshe River and Tongyu River. It was worthwhile to note that the soluble manganese content of the sediment in Mangshe River was even as high as 270 mg kg(-1), which suggested that the release of manganese from the sediment was the major cause of the pollution. The manganese content of the soil near the rivers was also determined, and the results indicated that the wastewater and waste slag discharged by the stainless steel factories nearby were the main pollution sources of manganese. Furthermore, the environmental factors affecting the release of manganese from the sediment were also investigated. PMID:20599319

Wang, Jinnan; Li, Aimin; Wang, Qiongjie; Zhou, Yang; Fu, Lichun; Li, Yan

2010-10-15

117

Efficiency of the Conversion of Low-Silicon Pig Iron with a Low Manganese Content in Oxygen Converters  

Microsoft Academic Search

A technology – the first of its kind in oxygen converter steelmaking – has been developed to make steel from low-silicon, low-manganese pig iron in 350-ton converters. Results are presented from a study of the dependence of the chemical composition and temperature of the pig iron on its manganese content. The first study ever is made of the processes of

R. S. Aizatulov; Yu. A. Pak; V. V. Sokolov; A. B. Yur'ev; V. A. Buimov; M. V. Glukhikh

2002-01-01

118

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

NASA Technical Reports Server (NTRS)

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.

Hoffman, Douglas C.; Potter, Benjamin

2013-01-01

119

Low Mn alloy steel for cryogenic service and method of preparation  

DOEpatents

A ferritic cryogenic steel which has a relatively low (about 4-6%) manganese content and which has been made suitable for use at cryogenic temperatures by a thermal cycling treatment followed by a final tempering. The steel includes 4-6% manganese, 0.02-0.06% carbon, 0.1-0.4% molybdenum and 0-3% nickel.

Morris, Jr., John W. (Berkeley, CA); Niikura, Masakazu (Yokohama, JP)

1981-01-01

120

Hadfield steel coatings on low carbon steel by laser cladding  

Microsoft Academic Search

Austenitic manganese steels with 12% Mn and 1.2% C, known as Hadfield steels, are of great interest owing to their good mechanical properties, especially their high strengthening ratio during plastic deformation. For many applications only a limited thickness of the surface layer is submitted to wear and therefore manufacturing of coatings with the appropriate Fe?Mn?C composition appears an attractive solution.

J. M. Pelletier; F. Oucherif; P. Sallamand; A. B. Vannes

1995-01-01

121

Hydrogen conversion on non-magnetic insulating surfaces  

NASA Astrophysics Data System (ADS)

Non-magnetic insulating catalysts are shown to be able to convert non-equilibrium mixtures of hydrogen by an electric mechanism. The molecular electrons feel the difference of temperature between the nuclei and the thermal bath, through their “Fermi” contact interaction, and consequently transfer the rotational angular momenta to the catalyst. This transfer, realized by the electrostatic interactions between the molecular and surface ionic electron clouds, is measured by non-diagonal exchange integrals. Our simple model of single-electron excitations interprets the experimental conversion rates recently observed on different surfaces (MOF or ASW) with different technics (infrared or ionization spectroscopy) and allows the study of the conversion rates in different contexts: thermal as well as transient, metallic or oxygen-induced, ion-molecule and molecule-molecule electron exchanges.

Ilisca, E.

2013-10-01

122

Insensitivity of tunneling anisotropic magnetoresistance to non-magnetic electrodes  

SciTech Connect

Ferromagnetic electrodes play a crucial role in magnetoresistance effect and spin injection, whereas the essential features of non-magnetic metal electrodes in spintronics are commonly ignored except for their electrical conductivity. Here, we verify that the room-temperature tunneling anisotropic magnetoresistance (TAMR) behavior in antiferromagnet-based [Pt/Co]/IrMn/AlO{sub x}/metal (metal?=?Pt, Au, Cu, Al) junctions is insensitive to the top metal electrodes. Similar out-of-plane signals are detected for different electrodes, in contrast to the varied shapes of in-plane TAMR curves which are most likely attributed to the differences in the multidomain structure of the magnetic electrode. This would add a different dimension to spintronics.

Wang, Y. Y.; Song, C., E-mail: songcheng@mail.tsinghua.edu.cn; Wang, G. Y.; Zeng, F.; Pan, F., E-mail: panf@mail.tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2013-11-11

123

Manganese, Metallogenium, and Martian Microfossils  

NASA Technical Reports Server (NTRS)

Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

Stein, L. Y.; Nealson, K. H.

1999-01-01

124

Slag Metal Reactions during Submerged Arc Welding of Alloy Steels  

E-print Network

) ) Slag Metal Reactions during Submerged Arc Welding of Alloy Steels U. MITRA and T. W. EAGAR for submerged arc welds made with calcium silicate and manganese silicate fluxes. The results show a strong on slag-metal reac- tions of submerged arc welds involving manganese, silicon, and oxygen transfer.1 -1

Eagar, Thomas W.

125

SOLUBLE MANGANESE REMOVAL BY POROUS MEDIA FILTRATION  

Microsoft Academic Search

Filtration experiments were conducted to investigate soluble manganese removal in granular media filtration; sand, manganese oxide coated sand (MOCS), sand + MOCS (1:1) and granular activated carbon (GAC) were used as filter media. Manganese removal, manganese oxide accumulation, turbidity removal, and regeneration of MOCS under various conditions were examined. Soluble manganese removal by the MOCS column was rapid and efficient;

J. Kim; S. Jung

2008-01-01

126

CONVERSATION OF DISSOLVED MANGANESE TO PARTICULATE MANGANESE DURING DIATOM BLOOM: EFFECTS ON THE MANGANESE CYCLE IN THE MERL MICROCOSMS  

EPA Science Inventory

Conversion of dissolved manganese to particulate manganese occurred during a minor diatom bloom during August and September 1978 in the MERL microcosms. Correlations between chlorophyll a and particulate manganese suggest that 29 moles Mn were transferred to the particulate phase...

127

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2010-04-01

128

Magnetic-field effects in non-magnetic glasses  

NASA Astrophysics Data System (ADS)

Recently, it was found that the multi-component glass a-BaO-Al2O3-SiO2 exhibits unusual magnetic properties at very low temperatures. Thus the question arises whether this is a specialty of that particular glass or a more general phenomenon. We report here on our studies of the magnetic-field dependence of the dielectric properties of the borosilicate glass BK7 which contains only a negligible amount of magnetic impurities. Since this glass also responds sensitively to magnetic fields, our investigations demonstrate that the reaction of glasses to magnetic fields is not caused by magnetic impurities but reflects a more general phenomenon. In addition, we have observed that the variation of the dielectric constant and the loss angle with magnetic field depend on the amplitude of the electric field that is used to measure the glass capacitance. We present the data and discuss possible origins of the magnetic-field phenomena in non-magnetic glasses.

Wohlfahrt, M.; Strehlow, P.; Enss, C.; Hunklinger, S.

2001-12-01

129

Giant spin Seebeck effect in a non-magnetic material.  

PubMed

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

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

2012-07-12

130

21 CFR 582.5455 - Manganese glycerophosphate.  

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b)...

2014-04-01

131

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2012 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b)...

2012-04-01

132

Frustrating interactions in oxides induced by non-magnetic impurities  

NASA Astrophysics Data System (ADS)

An antiferromagnetic host material doped with non-magnetic impurities, such as Zn-doped La2CuO4, is generally believed to represent an excellent model case of the site-dilution of a magnetic substance. We demonstrate that there exist a significant qualitative correction to such a picture: an impurity can induce substantial frustrating interactions between spins that are nearest neighbors of the impurity site. Not only this effect explains discrepancies between experimental data and the site-dilution theory, but it could also lead to some important modification of the behavior of doped antiferromagnets close to the percolation. We study the 2D, S=1/2 copper-oxide plane with Zn impurities starting from the microscopic three-band Hubbard model. We show that, for a wide range of the model parameters, the substantial superexchange interactions between the next- and next-next-nearest neighbor Cu spins around the impurity site can be generated via the virtual transitions through the oxygen orbitals. Surprisingly, the interaction across the impurity J''Zn is greater than the next-nearest neighbor interaction J'Zn due to a partial cancellation of the super- and the cyclic exchanges for the latter. This study is completed by the T-matrix calculation of the staggered magnetization M(x) as a function of Zn doping x. The predicted range of J'Zn and J''Zn agrees with the values needed to explain experimental deviation of M(x) from the results of the site-dilution theories.

Liu, Shiu; Chernyshev, Sasha

2006-03-01

133

The Interfacial Tension of Magnetic and Non-magnetic Dispersions  

NASA Astrophysics Data System (ADS)

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.

Johnson, D.

134

Interactions of pentachlorophenol with manganese oxide  

SciTech Connect

Abiotic interactions of pentachlorophenol (PCP) on manganese oxide surfaces were investigated to determine the extent of transformation. The optimal pH and ratio of manganese oxide to PCP were determined. Sorption of PCP on manganese oxide surfaces was quantified at optimal conditions. The effectiveness of utilizing manganese oxide to remediate contaminated subsurface environments was investigated.

Cramer, A.; McLean, J.E.; Sims, R.C. [Utah State Univ., Logan, UT (United States). Utah Water Research Lab.

1994-12-31

135

The Effect of Manganese Additions on the Reactive Evaporation of Chromium in Ni-Cr Alloys  

SciTech Connect

Chromium is used as an alloy addition in stainless steels and nickel-chromium alloys to form protective chromium oxide scales. Chromium oxide undergoes reactive evaporation in high temperature exposures in the presence of oxygen and/or water vapor. The deposition of gaseous chromium species onto solid oxide fuel cell electrodes can reduce the efficiency of the fuel cell. Manganese additions to the alloy can reduce the activity of chromium in the oxide, either from solid solution replacement of chromium with manganese (at low levels of manganese) or from the formation of manganese-chromium spinels (at high levels of manganese). This reduction in chromium activity leads to a predicted reduction in chromium evaporation by as much as a factor of 35 at 800 C and 55 at 700 C. The results of evaporation loss measurements on nickel-chromium-manganese alloys are compared with the predicted reduction. Quantifying the effects of manganese additions on chromium evaporation should aid alloy development of metallic interconnects and balance-of-plant alloys.

Holcomb, Gordon R.; Alman, David E.

2004-10-20

136

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

E-print Network

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 ...

Tejwani, Saurabh

2009-01-01

137

The new magnetic \\/ non-magnetic double degenerate system EUVE J1439+75.0  

Microsoft Academic Search

Optical spectroscopy of the extreme ultraviolet source EUVE J1439 + 75.0 revealed a new unresolved double degenerate system. The system is composed of two hot white dwarfs (T_eff>= 20, 000 K), one magnetic (~ 10 MG) and the other apparently non-magnetic. Surface gravity measurements imply masses of ~ 1.0 and ~ 0.9 M_solar for the magnetic and non-magnetic white dwarfs,

Stephane Vennes; Lilia Ferrario; Dayal T. Wickramasinghe

1999-01-01

138

PLC-9 Non Rusting Stainless Steel Column 10" Square with Radius Corners  

E-print Network

PLC-9 Non Rusting Stainless Steel Column 10" Square with Radius Corners Unit includes two lights General Specifications of PLC-9 Column Non Rusting, Non Magnetic Stainless Steel - .125" Thick Dimensions Centers, Elevators. Ramtel phones service: Universities & Colleges, Schools, Police Departments, Banks

Duchowski, Andrew T.

139

Recent developments in abrasion resistant high chromium-molybdenum irons, low-alloy manganese steels and alloyed nodular irons of importance in the extraction and utilization of energy resources  

Microsoft Academic Search

Advances in the technology of abrasion resistant irons and steels, which could help in combating abrasion and wear in the\\u000a extraction and utilization of energy resources, are reviewed. Nodular irons alloyed with nickel or copper and molybdenum,\\u000a with acicular, bainitic or bainitic-martensitic microstructures are described. These alloy irons combine excellent castability\\u000a and relatively easy machinability with good resistance to wear.

John Dodd

1980-01-01

140

Use of AES to determine low solubilities of impurities: Case of MnS in austenitic stainless steel  

SciTech Connect

The solubility of manganese sulfide in a commercial 304 austenitic stainless steel was studied using AES to determine surface sulfur segregation. The segregation mechanism at stainless steel surfaces were extensively studied, but thermodynamic data such as segregation free energy, or manganese sulfide dissolution heat have not been established, although these data are of great interest because the MnS dissolution parameters give the amount of free sulfur in solid solution. The only solubility data for manganese sulfide in austenitic steel was given to Turkdogan in 1955 and concerned MnS in iron-manganese alloys. In the present study, the Auger spectra are used to calculate the free energy of dissolution of manganese sulfide as well as the sulfur segregation parameters in austenitic stainless steel.

Hays, V.; Gall, R. le; Saindrenan, G. [ISITEM, Nantes (France). Lab. Genie des Materiaux] [ISITEM, Nantes (France). Lab. Genie des Materiaux; Roptin, D. [ECN, Nantes (France). Lab. Materiaux] [ECN, Nantes (France). Lab. Materiaux

1998-01-06

141

Influence of silicon in low density Fe-C-Mn-Al Steel Yoon-Uk Heoa  

E-print Network

) 1731-1735 #12;low-density steels containing low carbon, medium manganese of 6­8 wt. pct. have attractedInfluence of silicon in low density Fe-C-Mn-Al Steel Yoon-Uk Heoa , You-Young Songa , Seong on the microstructure of a Fe-Mn-Al-C ferritic low- density steel is investigated. The formation of -carbide, known

Cambridge, University of

142

Tellurium content of marine manganese oxides and other manganese oxides  

USGS Publications Warehouse

Tellurium in amounts ranging from 5 to 125 parts per million was present in all of 12 samples of manganese oxide nodules from the floor of the Pacific and Indian oceans. These samples represent the first recognized points of high tellurium concentration in a sedimentary cycle. The analyses may lend support to the theory that the minor-element content of seafloor manganese nodules is derived from volcanic emanations.

Lakin, H.W.; Thompson, C.E.; Davidson, D.F.

1963-01-01

143

Manganese oxidation model for rivers  

USGS Publications Warehouse

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 low pH conditions, or their combinations.

Hess, Glen W.; Kim, Byung R.; Roberts, Philip J.W.

1989-01-01

144

APT characterization of high nickel RPV steels  

NASA Astrophysics Data System (ADS)

The microstructures of three high nickel content pressure vessel steels have been characterized by atom probe tomography to investigate the influence of high nickel levels on the response to neutron irradiation of high and low copper pressure vessel steels. The high-nickel, low-manganese, low-copper VVER-1000 weld and forging exhibited lower than predicted levels of embrittlement during neutron irradiation. The Palisades weld exhibits a ? T41 J of 102 °C which was significantly lower than the value of 154 °C predicted by Reg. Guide 1.99 Rev. 2. Atom probe tomography revealed nickel-, manganese-, and silicon-enriched precipitates in both the VVER-1000 base and weld materials after neutron irradiation. A high number density of copper-, nickel-, manganese-, silicon- and phosphorus-enriched precipitates were observed in the Palisades weld after neutron irradiation. Atom probe tomography also revealed high levels of phosphorus segregation to the dislocations in all three materials.

Miller, M. K.; Sokolov, M. A.; Nanstad, R. K.; Russell, K. F.

2006-06-01

145

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

Microsoft Academic Search

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

Wensheng Zhang; Chu Yong Cheng

2007-01-01

146

Preclinical neurophysiological signs of parkinsonism in occupational manganese exposure.  

PubMed

To study the effects from low level exposure to manganese, 30 men at steel smelting works and 60 nonexposed reference subjects, were neurophysiologically examined using: (i) Electroencephalogram (EEG), Event related auditory evoked potential (AEP/P300), Brain stem auditory evoked potential (BAEP) and diadochokinesometry. No group differences concerning EEG or BAEP were found. Diadochokinesis was slower and there was a tendency towards prolonged P300 latency in the exposed group as compared to the referents. These effects may be interpreted as early (subclinical) signs of disturbances of the same type as parkinsonism. PMID:1508430

Wennberg, A; Hagman, M; Johansson, L

1992-01-01

147

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2011 CFR

...obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate is digested first with sufficient citric acid solution to form manganous citrate and then with sodium citrate to...

2011-04-01

148

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2013 CFR

...obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate is digested first with sufficient citric acid solution to form manganous citrate and then with sodium citrate to...

2013-04-01

149

21 CFR 184.1449 - Manganese citrate.  

...obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate is digested first with sufficient citric acid solution to form manganous citrate and then with sodium citrate to...

2014-04-01

150

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2012 CFR

...obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The filtered and washed precipitate is digested first with sufficient citric acid solution to form manganous citrate and then with sodium citrate to...

2012-04-01

151

21 CFR 582.5446 - Manganese chloride.  

Code of Federal Regulations, 2012 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use....

2012-04-01

152

21 CFR 582.5458 - Manganese hypophosphite.  

Code of Federal Regulations, 2011 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions...

2011-04-01

153

21 CFR 582.5446 - Manganese chloride.  

Code of Federal Regulations, 2011 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use....

2011-04-01

154

21 CFR 582.5449 - Manganese citrate.  

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use....

2014-04-01

155

21 CFR 582.5446 - Manganese chloride.  

Code of Federal Regulations, 2010 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use....

2010-04-01

156

21 CFR 582.5458 - Manganese hypophosphite.  

Code of Federal Regulations, 2013 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions...

2013-04-01

157

21 CFR 582.5461 - Manganese sulfate.  

Code of Federal Regulations, 2010 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use....

2010-04-01

158

21 CFR 582.5461 - Manganese sulfate.  

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use....

2014-04-01

159

21 CFR 582.5452 - Manganese gluconate.  

Code of Federal Regulations, 2010 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of...

2010-04-01

160

21 CFR 582.5458 - Manganese hypophosphite.  

Code of Federal Regulations, 2012 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions...

2012-04-01

161

21 CFR 582.5458 - Manganese hypophosphite.  

Code of Federal Regulations, 2010 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions...

2010-04-01

162

Approach towards full Heusler alloy based CPP-GMR: from Ag and non-magnetic Heusler to binary intermetallic spacers  

Microsoft Academic Search

Recently, it has been demonstrated that GMR response can be significantly enhanced by incorporating high spin polarization ferromagnetic (FM) full Heulser alloy into spin valve nano-structures. Experimental results for two types of non-magnetic spacers (i) elemental metal [1] and (ii) non-magnetic Heusler alloy spacers [2] deserve careful comparison. More practical (110) textured combination of Co2MnGe (CMG) and non-magnetic Heusler alloy

Oleg Mryasov; Sergey Faleev; S. V. Karthik

2011-01-01

163

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

E-print Network

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.

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

2005-06-27

164

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2010 CFR

...a) Manganese citrate (Mn3 (C6 H5 O7 )2 , CAS Reg. No. 1002-46-65) is a pale orange or pinkish white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions....

2010-04-01

165

Manganese binding to the prion protein.  

PubMed

There is considerable evidence that the prion protein binds copper. However, there have also been suggestions that prion protein (PrP) binds manganese. We used isothermal titration calorimetry to identify the manganese binding sites in wild-type mouse PrP. The protein showed two manganese binding sites with affinities that would bind manganese at concentrations of 63 and 200 mum at pH 5.5. This indicates that PrP binds manganese with affinity similar to other known manganese-binding proteins. Further study indicated that the main manganese binding site is associated with His-95 in the so-called "fifth site" normally associated with copper binding. Additionally, it was shown that occupancy by copper does not prevent manganese binding. Under these conditions, manganese binding resulted in an altered conformation of PrP, displacement of copper, and altered redox chemistry of the metal-protein complex. Cyclic voltammetric measurements suggested a complex redox chemistry involving manganese bound to PrP, whereas copper-bound PrP was able to undergo fully reversible electron cycling. Additionally, manganese binding to PrP converted it to a form able to catalyze aggregation of metal-free PrP. These results further support the notion that manganese binding could cause a conformation change in PrP and trigger changes in the protein similar to those associated with prion disease. PMID:18332141

Brazier, Marcus W; Davies, Paul; Player, Esmie; Marken, Frank; Viles, John H; Brown, David R

2008-05-01

166

Manganese depresses rat heart muscle respiration  

Technology Transfer Automated Retrieval System (TEKTRAN)

It has previously been reported that moderately high dietary manganese (Mn) in combination with marginal magnesium (Mg) resulted in ultrastructural damage to heart mitochondria. Manganese may replace Mg in biological functions, including the role of enzyme cofactor. Manganese may accumulate and subs...

167

Congrs Franais de Mcanique Bordeaux, 26 au 30 aot 2013 Delamination of pipeline steels: determination of an  

E-print Network

was used (Fig. 1a). It is a micro-alloyed low carbon manganese steel. Its 0.2% proof stress, tensile studied on a ferrite-bainite low alloy pipeline steel plate. Mechanical tests have been performed to be related to microtexture anisotropy and might explain the sensitivity of this steel to delamination at low

Paris-Sud XI, Université de

168

PART III M21 STEELS: ANSWER SHEET 2 (1) A high silicon concentration prevents the precipitation of cementite during the  

E-print Network

of transformation. Hence can form at low undercoolings. 1 #12;2 PART III M21 STEELS: ANSWER SHEET 2 (3) Combination highly mobile. Thus, in a steel, manganese does not partition between the ferrite and austenitePART III M21 STEELS: ANSWER SHEET 2 (1) A high silicon concentration prevents the precipitation

Cambridge, University of

169

BRITTLE FRACTURE IN HEAT-AFFECTED ZONES OF GIRTH WELDS OF MODERN LINE PIPE STEEL (X100)  

E-print Network

-affected zone (HAZ). The modern low carbon steel X100 contains manganese and some silicon, molybdenum and nickelBRITTLE FRACTURE IN HEAT-AFFECTED ZONES OF GIRTH WELDS OF MODERN LINE PIPE STEEL (X100) A.-S. BILAT welds of modern line pipe steel, such as X100, issued from a pulsed automatic gas metal arc welding

Paris-Sud XI, Université de

170

Manganese toxicity upon overexposure  

PubMed Central

Manganese (Mn) is a required element and a metabolic byproduct of the contrast agent mangafodipir trisodium (MnDPDP). The Mn released from MnDPDP is initially sequestered by the liver for first-pass elimination, which allows an enhanced contrast for diagnostic imaging. The administration of intravenous Mn impacts its homeostatic balance in the human body and can lead to toxicity. Human Mn deficiency has been reported in patients on parenteral nutrition and in micronutrient studies. Mn toxicity has been reported through occupational (e.g. welder) and dietary overexposure and is evidenced primarily in the central nervous system, although lung, cardiac, liver, reproductive and fetal toxicity have been noted. Mn neurotoxicity results from an accumulation of the metal in brain tissue and results in a progressive disorder of the extrapyramidal system which is similar to Parkinson's disease. In order for Mn to distribute from blood into brain tissue, it must cross either the blood–brain barrier (BBB) or the blood–cerebrospinal fluid barrier (BCB). Brain import, with no evidence of export, would lead to brain Mn accumulation and neurotoxicity. The mechanism for the neurodegenerative damage specific to select brain regions is not clearly understood. Disturbances in iron homeostasis and the valence state of Mn have been implicated as key factors in contributing to Mn toxicity. Chelation therapy with EDTA and supplementation with levodopa are the current treatment options, which are mildly and transiently efficacious. In conclusion, repeated administration of Mn, or compounds that readily release Mn, may increase the risk of Mn-induced toxicity. PMID:15617053

Crossgrove, Janelle; Zheng, Wei

2014-01-01

171

Biomarkers of Manganese Intoxication  

PubMed Central

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

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

2010-01-01

172

ADVANCEMENTS IN STEEL FOR WEIGHT REDUCTION OF P900 ARMOR PLATE  

Microsoft Academic Search

Ballistic tests were conducted on a high manganese and high aluminum austenitic steel that is age hardenable. These lightweight steels (12 to 18% lower in density) were investigated as alternatives to MIL-PRF- 32269 steel alloys for application in P900 perforated armor currently used for Army ground combat systems. Two steel plates with nominal composition in weight percent of Fe-30Mn-9Al-1Si-0.9C-0.5Mo were

R. A. Howell; J. S. Montgomery; D. C. Van Aken

173

Manganese mineral interactions in brain.  

PubMed

Manganese (Mn) is an essential mineral but is toxic when taken in excess. However, whether its interactions with other minerals in organs and cells are involved in mechanisms underlying Mn toxicity is poorly understood. We designed a developmental rat model of chronic Mn treatment (Group A: 1 mg MnCl2.4H2O per ml of drinking water; Group B: 10 mg MnCl2.4H2O per ml of drinking water; Group C: 20 mg MnCl2.4H2O per ml of drinking water; Control Group given water without manganese addition). Employing the model and instrumental neutron activation analysis, we investigated two hypotheses: (i) chronic manganese treatment alters the brain regional distribution of manganese and this altered manganese distribution also leads to region-specific changes of other metals; (ii) chronic manganese treatment induces differential changes in subcellular distributions of metals and electrolytes. In the treated rats, brain Mn level showed dose-related increases, the most pronounced being noted in striatum, hypothalamus, and hippocampus: these increases also led to alterations in regional distribution pattern of Mn. In the treated rats, Fe level was increased in hypothalamus, cerebellum, hippocampus, pons and medulla, and striatum. Cu level was increased in pons and medulla, hippocampus, midbrain, and striatum. Se level was increased in cerebellum, striatum, midbrain, hypothalamus, and pons and medulla. Zn level was increased in hypothalamus and striatum. Ca level was increased in midbrain but decreased in cerebellum; however, Mg and Al levels were not markedly affected. In brains of Mn-treated rats, Mn levels in subcellular fractions were all increased, being especially marked in nuclei, mitochondria, and synaptosomes; the subcellular distributions of Fe, Cu, Zn, and Mg were differentially altered although those of Al and Ca were minimally affected. These results are consistent with our hypotheses and may have implications in manganese neurotoxicity. The cellular and molecular mechanisms underlying manganese-mineral interactions in brain are still poorly defined and merit further investigation. PMID:10385902

Lai, J C; Minski, M J; Chan, A W; Leung, T K; Lim, L

1999-01-01

174

Non-magnetic impurities and in-gap bound states in topological insulators  

NASA Astrophysics Data System (ADS)

In-gap bound states induced by non-magnetic impurities in various dimensional topological insulators are investigated based on a modified Dirac model that considers quadratic corrections to the mass term. Their existence and features greatly rely on the potential form of the impurity as well as the dimensionality of the topological insulator. It is analytically proven that the impurity potential modeled by the delta function can induce the bound states in one dimension (1D), but not in two and three. For a single non-magnetic impurity with a general isotropic potential, formal solutions are obtained and further numerical calculations are performed. In particular, the in-gap bound states induced by a non-magnetic impurity with isotropic Gaussian potentials in two-dimensional (2D) and three-dimensional (3D) topological insulators are numerically investigated. Information on how many in-gap bound states can be trapped by a non-magnetic Gaussian impurity is presented for the parameters from a series of topologically non-trivial materials.

Lu, Jie; Shan, Wen-Yu; Lu, Hai-Zhou; Shen, Shun-Qing

2011-10-01

175

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

SciTech Connect

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.

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

176

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

177

State-of-the-Science Review: Does Manganese Exposure During Welding Pose a Neurological Risk?  

Microsoft Academic Search

Recent studies report that exposure to manganese (Mn), an essential component of welding electrodes and some steels, results in neurotoxicity and\\/or Parkinson's disease (PD) in welders. This “state-of-the-science” review presents a critical analysis of the published studies that were conducted on a variety of Mn-exposed occupational cohorts during the last 100 yr, as well as the regulatory history of Mn

Annette B. Santamaria; Colleen A. Cushing; James M. Antonini; Brent L. Finley; Fionna S. Mowat

2007-01-01

178

Intergranular corrosion behaviour of a new austenitic stainless steel low in nickel  

Microsoft Academic Search

A comparative study was done on the intergranular corrosion resistance of AISI 304 stainless steel and a new austenitic stainless steel currently being developed, in which the concentration of nickel is less than 2%. The austenitic effect of nickel is replaced by other alloying elements, mainly manganese. The experimental results are discussed according to ASTM A-262, practices C and E

E. Otero; A. Pardo; E. Sáenz; V. Utrilla; F. J. Pérez

1995-01-01

179

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

SciTech Connect

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.

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

180

Apparatus and method for continuous separation of magnetic particles from non-magnetic fluids  

DOEpatents

A magnetic separator vessel (1) for separating magnetic particles from non-magnetic fluid includes a separation chamber having an interior and exterior wall, a top and bottom portion; a magnet (3) having first and second poles (2) positioned adjacent to the exterior wall, wherein the first pole is substantially diametrically opposed to the second pole; a inlet port (5) is directed into the top portion of the separation chamber, wherein the inlet port (5) is positioned adjacent to one of the first and second poles (2), wherein the inlet port (5) is adapted to transfer a mixture into the separation chamber; an underflow port (6) in communication with the bottom portion, wherein the underflow port (6) is adapted to receive the magnetic particles; and an overflow port (9) in communication with the separation chamber, wherein the overflow port (9) is adapted to receive the non-magnetic fluid.

Oder, Robin R. (Export, PA); Jamison, Russell E. (Lower Burrell, PA)

2010-02-09

181

Environmental Controls of Biological Manganese Oxidation  

NASA Astrophysics Data System (ADS)

Biological catalysis of manganese oxidation represents an important contribution to global manganese cycling; biological oxidation rates are several orders of magnitude higher than those of abiotic processes. Despite recent genetics advances, ongoing behavioral studies, and a large pool of knowledge regarding manganese chemistry, the links between biology and environmental chemistry remain unresolved. We have performed experiments on batch cultures of Leptothrix discophora SS-1 to explore the physiology of biological manganese oxidation. We have further conducted spectroscopic and microscopic studies of the mechanism as manganese proceeds from the soluble Mn2+ species to the insoluble Mn(III) and Mn(IV) phases. These investigations suggest roles for aqueous chemistry, mineralogy, and microbial physiology in controlling manganese fluxes in metal-rich environments.

Belz, A. P.; Ahn, C. C.; Nealson, K. H.

2001-12-01

182

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...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2012-07-01

183

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

...2014-07-01 2014-07-01 false Cobalt lithium manganese nickel oxide. 721.10201...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2014-07-01

184

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...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2013-07-01

185

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

186

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 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...

2010-07-01

187

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

188

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

189

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

...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...

2014-07-01

190

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

Microsoft Academic Search

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

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

2008-01-01

191

Spectroscopic characterization of manganese minerals  

NASA Astrophysics Data System (ADS)

Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals.

Lakshmi Reddy, S.; Padma Suvarna, K.; Udayabhaska Reddy, G.; Endo, Tamio; Frost, R. L.

2014-01-01

192

Microbial Formation of Manganese Oxides  

PubMed Central

Microbial manganese oxidation was demonstrated at high Mn2+ 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 (?-MnOOH). Bacteria isolated from associations with crude cultures of this alga grown in aerated bioreactors formed disordered ?-MnO2 from Mn2+ at concentrations of 5 g/liter over 1 month, yielding 3.3 g of a semipure oxide per liter. All algal-bacterial cultures removed Mn2+ 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 ?-MnO2, 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 ?-MnO2 (ca. 50%). The shortfall in the bacterial oxide manganese content was due to biological and inorganic contaminants. FTIR spectroscopy, transmission electron microscopy, and electron diffraction studies have identified manganite as a likely intermediate product in the formation of disordered ?-MnO2. PMID:16348459

Greene, Anthony C.; Madgwick, John C.

1991-01-01

193

[Analysis of alloy tool steel using X-ray fluorescence spectrometer].  

PubMed

This report briefly introduces the analysis of Mn, Cr, V, W, Ti, Nb, Co, Zr, Ni, Mo, S, P, Si and Cu in alloy tool steel with X-ray florescence spectrometer. After being polished with grinding well and being cleaned with ethly alcohol, the test samples can be directly measured, and the results agree well with the standard values of the laboratory standards. The precision of the method (RSD) is in the range of 0.13%-9.56% (n = 8) for all elements except W, Ti, Nb and Zr. The method can be applied to many kinds of steel, such as chrome vanadium steel, manganese steel, die steel, middle-low alloy steel, tool steel. The measure instrument should be rectified with two or three standard samples which the quantity contained is suitable. The standard samples include 1Cr18Ni9Ti, C17Ni2, 25CrMo1V, 30CrMnSiA, 3CrW8V, Gx-8, Cr12MoV, chrome vanadium steel, manganese-boron steel, middle-low alloy steel and other kinds of steel. If there is not conditions to make work curves for all kinds steel separately, sometimes we don't know what kind of steel for one complex sample, the more real way will be to make an overall work curves which contains more kinds of steel as far as possible. PMID:12945299

Zhou, S; Cai, Y; Huang, Z

2001-08-01

194

Role of manganese: Are welders at risk?.  

E-print Network

??Serious concerns exist among welders and occupational health investigators on the possible association between exposure to manganese via welding fumes and neurological effects. One suggestion… (more)

Nawrocki, R.P.

2012-01-01

195

Sulfide shape control in high strength low alloy steels  

Microsoft Academic Search

Directionality of mechanical properties—such as toughness and bend formability—is typical of hot rolled steels processed on\\u000a modern, hot strip mills. In aluminum killed steels, directionality results mainly from elongated (type II) manganese sulfide\\u000a inclusions. Directionality can be reduced by retaining the original globular shape of the precipitated sulfides. This can\\u000a be accomplished by promoting the formation of sulfides which are

Leon Luyckx; John R. Bell; Alex McLean; Michael Korchynsky

1970-01-01

196

Fatigue Property of Stainless Steel FES Electrode in Hanks' Solution  

Microsoft Academic Search

Fatigue property of the wire rope with 19 strands used as an FES electrode was investigated. The wire rope was made of high manganese high nitrogen austenitic stainless steel. Fatigue life of the wire rope in Hanks' solution at 310 K was evaluated using a dual-driven rotating-bending fatigue machine. Each wire of the rope was worn out and the cross

Y. Iguchi; T. Narushima; K. Suzuki; S. Yoshida; M. Watanabe; T. Kinami; C. Ouchi

197

Non-magnetic and magnetic impurity effects on superconductivity in the ternary iron-silicide Lu2FeSi  

NASA Astrophysics Data System (ADS)

We studied effect of non-magnetic and magnetic impurities on superconductivity in LuFeSi by investigating superconducting properties of (LuFeSi (R=Sc,Y, and Dy). The rapid depression of Tc by non-magnetic impurities reveals strong pair breaking by disorder, providing compelling evidence for the sign reversal of the superconducting order parameter in LuFeSi.

Watanabe, Tadataka; Okuyama, Hiroaki; Takase, Kouichi; Takano, Yoshiki

2010-12-01

198

Non-magnetic and magnetic impurity effects on superconductivity in the ternary iron-silicide LuFeSi  

NASA Astrophysics Data System (ADS)

We studied effect of non-magnetic and magnetic impurities on superconductivity in LuFeSi by investigating superconducting properties of (LuFeSi ( R=Sc,Y, and Dy). The rapid depression of Tc by non-magnetic impurities reveals strong pair breaking by disorder, providing compelling evidence for the sign reversal of the superconducting order parameter in LuFeSi.

Watanabe, Tadataka; Okuyama, Hiroaki; Takase, Kouichi; Takano, Yoshiki

199

On Manganese in Sea and Fresh Waters  

Microsoft Academic Search

Chemical and spectrographic analyses have shown that the sea contains a variable quantity of manganese, ranging between 1 ~d 10 mg.jm.3 (Thomp- son & Wilson, 1935; Noddack & Noddack, 1940), while river waters contain some 500 to 1000 mg.jm.3 (Twenhofel, 1938). These 'estimates include manganese in solution and that present as particulate or colloidal oxides soluble in concentrated hydrochloric acid.

H. W. Harvey

1949-01-01

200

Ennoblement of stainless steel studied by x-ray photoelectron spectroscopy  

SciTech Connect

Manganese oxides deposited by biofilms of Leptothrix discophora SP-6 on 316L stainless steel corrosion coupons increased the open circuit potential of the steel to values of +375 mV{sub SCE}. XPS spectra of the deposits compared to spectra of different manganese containing minerals indicated that the deposits were composed of MnO{sub 2}. The redox reaction responsible for the potential change results in electron transfer from the metal substratum to the mineral deposit. To study the processes of manganese dioxide reduction, MnO{sub 2} which had been electroplated on stainless steel was reduced electrochemically. The surface chemistry before and after reduction was analyzed by XPS. The authors demonstrated that the manganese dioxide deposited on stainless steel coupons can be reduced to Mn{sup 2+} by accepting two electrons from the metal. MnOOH was identified as an unstable intermediate product in this reaction. Consequently they hypothesize, that manganese dioxide microbially deposited on stainless steel surfaces can provide an efficient cathodic reaction and accelerate microbially influenced corrosion processes.

Olesen, B.H. [Montana State Univ., Bozeman, MT (United States). Center for Biofilm Engineering; [Aalborg Univ. (Denmark). Environmental Engineering Lab.; Avci, R.; Lewandowski, Z. [Montana State Univ., Bozeman, MT (United States)

1998-12-31

201

Damage of TWIP Steels for Automotive Application ICF 12, Ottawa, Canada, 2009  

E-print Network

a recrystallized Fe-Mn-C steel sheet of 1.5mm in thickness, containing 0.6% of carbon and 22% of manganese. The grain size is 2-31m. The composition of the steel under investigation was optimized to exhibit a low SFEDamage of TWIP Steels for Automotive Application ­ICF 12, Ottawa, Canada, 2009 J.Lorthios,1 A

Paris-Sud XI, Université de

202

Mössbauer and X-ray phase analysis of carburized steel  

Microsoft Academic Search

57Fe backscattering Mössbauer phase analysis of the ASTM A295-70 type chromium bearing steel gas was performed for samples with varying phase composition achieved by gas carburization up to 3 wt% C followed by standard hardening, i.e. austenitizing and quenching procedures. Variations of contents of principal metallographic phases (alloyed martensite, austenite, magnetic and non-magnetic carbides) were determined and compared with reported

T. Zemcík; J. Suwalski; Z. Kucharski; M. Lukasiak

1994-01-01

203

Manganese borohydride; synthesis and characterization.  

PubMed

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[combining macron]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

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

2015-02-17

204

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

SciTech Connect

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.

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

2006-09-01

205

Nonlinear motion of coupled magnetic vortices in ferromagnetic/non-magnetic/ferromagnetic trilayer  

SciTech Connect

We have investigated a coupled motion of two vortex cores in ferromagnetic/nonmagnetic/ferromagnetic trilayer cynliders by means of micromagnetic simulation. Dynamic motion of two vortex with parallel and antiparallel relative chiralities of curling spins around the vortex cores have been examined after excitation by 1-ns pulsed external field. With systematic variation in non-magnetic spacer layer thickness from 0 to 20 nm, the coupling between two cores becomes significant as the spacer becomes thinner. Significant coupling leads to a nonlinear chaotic coupled motion of two vortex cores for the parallel chiralities and a faster coupled gyrotropic oscillation for the antiparallel chiralities.

Jun, Su-Hyeong; Shim, Je-Ho; Oh, Suhk-Kun; Yu, Seong-Cho; Kim, Dong-Hyun; Mesler, Brooke; Fischer, Peter

2009-07-05

206

Cerium heavy-fermion compounds near their T = 0 magnetic-non-magnetic boundary  

SciTech Connect

Measurements of the temperature-dependent specific heat and thermal expansion coefficient near a T = 0 magnetic-non-magnetic boundary, accessed in CeRh{sub 2}Si{sub 2} by application of pressure and in CeRh{sub 2{minus}x}Ru{sub x}Si{sub 2} at ambient pressure by chemical substitution, emphasize the role of disorder in producing non-Fermi-liquid behavior. Interestingly, superconductivity also develops near this boundary in some crystallographically-ordered Ce-based heavy-fermion compounds.

Thompson, J.D.; Hundley, M.F.; Movshovich, R.; Sarrao, J.L. [Los Alamos National Lab., NM (United States); Graf, T. [ETH Hoenggerberg, Zurich (Switzerland); Uwatoko, Y. [Saitama Univ., Urawa (Japan). Faculty of Science; Fisk, Z. [Florida State Univ., Tallahassee, FL (United States); Fisher, R.A.; Phillips, N.E. [Lawrence Berkeley National Lab., CA (United States); [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

1997-12-01

207

The removal of nickel dissolved in Pb—17Li by the formation of a less soluble nickel—manganese alloy  

NASA Astrophysics Data System (ADS)

Structural steels are susceptible to dissolution when exposed to liquid Pb—17Li. In order to remove the corrosion products transferred into the alloy, purification systems may be used. The efficiency of a cold trap fitted to the Anapurna liquid metal loop has been studied. The removal of nickel from solution in Pb—17Li has been shown to be possible by adding manganese to the Pb—17Li. Experiments carried out with a cold trap temperature of 523 K and an alloy temperature of 673 K have shown that nickel concentration as low as 1 wppm may be achieved by this method. The result is interpreted by the formation of nickel—manganese compounds deposited in the cold parts of the trap. This observation which suggests an interaction between both nickel and manganese in Pb—17Li is confirmed by equilibrium tests of Ni sbnd Mn alloys with Pb—17Li.

Barker, M. G.; Siddons, D. J.; Barbier, F.

1996-10-01

208

Manganese metallurgy review. Part I: Leaching of ores\\/secondary materials and recovery of electrolytic\\/chemical manganese dioxide  

Microsoft Academic Search

The world rapidly growing demand for manganese has made it increasingly important to develop processes for economical recovery of manganese from low grade manganese ores and other secondary sources. Part I of this review outlines metallurgical processes for manganese production from various resources, particularly focusing on recent developments in direct hydrometallurgical leaching and recovery processes to identify potential sources of

Wensheng Zhang; Chu Yong Cheng

2007-01-01

209

Kramers non-magnetic superconductivity in LnNiAsO superconductors.  

PubMed

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

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

2014-10-22

210

The Manganese Toxicity of Cotton 1  

PubMed Central

Cotton plants (Gossypium hirsutum. Linn. var. Sankar 4) were grown at normal and toxic levels of substrate manganese, and the altered metabolism of manganese toxic plants was studied. The tissues of plants exposed to toxic levels of manganese had higher activities of peroxidase and polyphenol oxidase, and the activities of catalase, ascorbic acid oxidase, glutathione oxidase and cytochrome c oxidase were lowered. In addition, the high manganese tissue had lower contents of ATP and glutathione but higher amounts of ascorbic acid. The respiration of the partially expanded leaves and the growing tips of toxic plants were depressed when compared to that of the normal tissues. The metabolic changes of manganese toxicity of cotton are placed in the following order: accumulation of manganese in the leaf tissue; a rise in respiration; stimulation of polyphenol oxidase; the appearance of initial toxicity symptoms; the evolution of ethylene and stimulation of peroxidase; the presence of severe toxicity symptoms; the depression of terminal oxidases and respiration; abscission of the growing tip and proliferation of the stem tissue. The early stimulation of polyphenol oxidase may be used to detect potential manganese toxicity. PMID:16658924

Sirkar, Sheela; Amin, J. V.

1974-01-01

211

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2010 CFR

...Identity. The color additive manganese violet...be avoided by good manufacturing practice: Ash...filtrate of 10 grams color additive (shaken occasionally...consistent with good manufacturing practice. (d) Labeling. The color additive and any...

2010-04-01

212

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2011 CFR

...Identity. The color additive manganese violet...be avoided by good manufacturing practice: Ash...filtrate of 10 grams color additive (shaken occasionally...consistent with good manufacturing practice. (d) Labeling. The color additive and any...

2011-04-01

213

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...

214

21 CFR 73.2775 - Manganese violet.  

...Identity. The color additive manganese violet...be avoided by good manufacturing practice: Ash...filtrate of 10 grams color additive (shaken occasionally...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2014-04-01

215

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2013 CFR

...Identity. The color additive manganese violet...be avoided by good manufacturing practice: Ash...filtrate of 10 grams color additive (shaken occasionally...consistent with good manufacturing practice. (d) Labeling. The color additive and any...

2013-04-01

216

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2012 CFR

...Identity. The color additive manganese violet...be avoided by good manufacturing practice: Ash...filtrate of 10 grams color additive (shaken occasionally...consistent with good manufacturing practice. (d) Labeling. The color additive and any...

2012-04-01

217

21 CFR 184.1446 - Manganese chloride.  

Code of Federal Regulations, 2011 CFR

...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

2011-04-01

218

21 CFR 184.1446 - Manganese chloride.  

Code of Federal Regulations, 2013 CFR

...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

2013-04-01

219

21 CFR 184.1446 - Manganese chloride.  

...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

2014-04-01

220

21 CFR 184.1446 - Manganese chloride.  

Code of Federal Regulations, 2010 CFR

...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

2010-04-01

221

21 CFR 184.1446 - Manganese chloride.  

Code of Federal Regulations, 2012 CFR

...ore (MnO2 ), or reduced manganese ore in hydrochloric acid. The resulting solution is neutralized to precipitate heavy metals, filtered, concentrated, and crystallized. (b) The ingredient meets the specifications of the Food...

2012-04-01

222

Toenail, Blood and Urine as Biomarkers of Manganese Exposure  

PubMed Central

Objective This study examined the correlation between manganese exposure and manganese concentrations in different biomarkers. Methods Air measurement data and work histories were used to determine manganese exposure over a workshift and cumulative exposure. Toenail samples (n=49), as well as blood and urine before (n=27) and after (urine, n=26; blood, n=24) a workshift were collected. Results Toenail manganese, adjusted for age and dietary manganese, was significantly correlated with cumulative exposure in months 7-9, 10-12, and 7-12 before toenail clipping date, but not months 1-6. Manganese exposure over a work shift was not correlated with changes in blood nor urine manganese. Conclusions Toenails appeared to be a valid measure of cumulative manganese exposure 7 to 12 months earlier. Neither change in blood nor urine manganese appeared to be suitable indicators of exposure over a typical workshift. PMID:21494156

Laohaudomchok, Wisanti; Lin, Xihong; Herrick, Robert F.; Fang, Shona C.; Cavallari, Jennifer M.; Christiani, David C.; Weisskopf, Marc G.

2011-01-01

223

alpha-Manganese Phases containing Technetium99  

Microsoft Academic Search

THE existence of alpha-manganese phases in the zirconium-technetium, niobium-technetium and molybdenum-technetium systems was recently reported by V. B. Compton et al.1. During the course of our investigation of alloy phases involving technetium-99 with transition metals, alpha-manganese phases were found in the binary systems scandium-technetium, titanium-technetium, hafnium-technetium and tantalum-technetium. Pertinent information is given in Table 1. The alloys were made by

D. J. Lam; J. B. Darby; J. W. Downey; L. J. Norton

1961-01-01

224

Position-dependent effect of non-magnetic impurities on superconducting properties of nanowires  

NASA Astrophysics Data System (ADS)

Anderson's theorem states that non-magnetic impurities do not change the bulk properties of conventional superconductors. However, as the dimensionality is reduced, the effect of impurities becomes more significant. Here we investigate superconducting nanowires with diameter comparable to the Fermi wavelength ?F (which is less than the superconducting coherence length) by using a microscopic description based on the Bogoliubov-de Gennes method. We find that: 1) impurities strongly affect the superconducting properties, 2) the effect is impurity position dependent, and 3) it exhibits opposite behavior for resonant and off-resonant wire widths. We show that this is due to the interplay between the shape resonances of the order parameter and the subband energy spectrum induced by the lateral quantum confinement. These effects can be used to manipulate the Josephson current, filter electrons by subband and investigate the symmetries of the superconducting subband gaps.

Zhang, L.-F.; Covaci, L.; Peeters, F. M.

2015-01-01

225

Magnesium and Manganese Content of Halophilic Bacteria  

PubMed Central

Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 M NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H. cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation. Images PMID:16347151

Médicis, Eveline De; Paquette, Jean; Gauthier, Jean-Jacques; Shapcott, Dennis

1986-01-01

226

Pathophysiology of Manganese-Associated Neurotoxicity  

PubMed Central

Conference Summary 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 J, 1955) Exposures associated with this syndrome were massive and an order of magnitude greater than modern exposures.(Rodier J, 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 C. 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

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

2012-01-01

227

Biogeochemical cycling of manganese in Oneida Lake, New York: whole lake studies of manganese  

NASA Technical Reports Server (NTRS)

Oneida Lake, New York is a eutrophic freshwater lake known for its abundant manganese nodules and a dynamic manganese cycle. Temporal and spatial distribution of soluble and particulate manganese in the water column of the lake were analyzed over a 3-year period and correlated with other variables such as oxygen, pH, and temperature. Only data from 1988 are shown. Manganese is removed from the water column in the spring via conversion to particulate form and deposited in the bottom sediments. This removal is due to biological factors, as the lake Eh/pH conditions alone can not account for the oxidation of the soluble manganese Mn(II). During the summer months the manganese from microbial reduction moves from the sediments to the water column. In periods of stratification the soluble Mn(II) builds up to concentrations of 20 micromoles or more in the bottom waters. When mixing occurs, the soluble Mn(II) is rapidly removed via oxidation. This cycle occurs more than once during the summer, with each manganese atom probably being used several times for the oxidation of organic carbon. At the end of the fall, whole lake concentrations of manganese stabilize, and remain at about 1 micromole until the following summer, when the cycle begins again. Inputs and outflows from the lake indicate that the active Mn cycle is primarily internal, with a small accumulation each year into ferromanganese nodules located in the oxic zones of the lake.

Aguilar, C.; Nealson, K. H.

1998-01-01

228

Study of high performance alloy electroforming. [nickel manganese and nickel cobalt manganese alloys  

NASA Technical Reports Server (NTRS)

Nickel-manganese alloy electrodeposits from an electrolyte containing more manganese ion than previously used is being evaluated at two bath operating temperatures with a great variety of pulse plating conditions. Saccharine was added as a stress reducing agent for the electroforming of several of the samples with highest manganese content. All specimens for mechanical property testing have been produced but are not through the various heat treatments as yet. One of the heat treatment will be at 343 C (650 F), the temperature at which the MCC outer electroformed nickel shell is stress relieved. A number of retainer specimens from prior work have been tested for hardness before and after heat treatment. There appears to be a fairly good correlation between hardness and mechanical properties. Comparison of representative mechanical properties with hardnesses are made for nickel-manganese electrodeposits and nickel-cobalt-manganese deposits.

Malone, G. A.

1984-01-01

229

Wear evaluation of high interstitial stainless steel  

SciTech Connect

A new series of high nitrogen-carbon manganese stainless steel alloys are studied for their wear resistance. High nitrogen and carbon concentrations were obtained by melting elemental iron-chromium-manganese (several with minor alloy additions of nickel, silicon, and molybdenum) in a nitrogen atmosphere and adding elemental graphite. The improvement in material properties (hardness and strength) with increasing nitrogen and carbon interstitial concentration was consistent with previously reported improvements in similar material properties alloyed with nitrogen only. Wear tests included: scratch, pin-on-disk, sand-rubber-wheel, impeller, and jet erosion. Additions of interstitial nitrogen and carbon as well as interstitial nitrogen and carbide precipitates were found to greatly improve material properties. In general, with increasing nitrogen and carbon concentrations, strength, hardness, and wear resistance increased.

Rawers, J.C.; Tylczak, J.H.

2008-07-01

230

A first-principles study on magnetocrystalline anisotropy at interfaces of Fe with non-magnetic metals  

NASA Astrophysics Data System (ADS)

Magnetocrystalline anisotropy (MCA) of Fe(001) interfaces with various non-magnetic metals (Hf, Zr, Ti, Ta, Nb, V, Ir, Rh, Pt, Pd, Au, Ag, Cu, and Zn) was investigated by first-principles calculations. We found that Fe interfaces with non-magnetic metals with fully occupied d states tend to show perpendicular MCA. The spin-orbit coupling in interfacial Fe atoms plays an important role in perpendicular MCA. Conversely, Fe interfaces with non-magnetic metals with partially occupied d states exhibit in-plane MCA. The Hf/Fe(001) interface shows an exceptionally large perpendicular MCA energy of 1.5 mJ/m2, which corresponds to that of the MgO/Fe(001) interface. In these cases, contributions from interfacial Fe atoms to MCA are relatively small, and the large spin-orbit coupling of non-magnetic atoms is the primary contribution to MCA. We conclude that formation of Hf/Fe(001) interfaces will enhance the perpendicular magnetization of MgO/CoFeB-based magnetic tunnel junctions.

Miura, Yoshio; Tsujikawa, Masahito; Shirai, Masafumi

2013-06-01

231

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

PubMed

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

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

2000-10-01

232

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

NASA Astrophysics Data System (ADS)

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.

Arnold, Michelle Lynn

2001-11-01

233

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

SciTech Connect

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.

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

234

Manganese oxide reduction as a form of anaerobic respiration  

Microsoft Academic Search

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

Henry L. Ehrlich

1987-01-01

235

Essentiality, Toxicity and Uncertainty in the Risk Assessment of Manganese  

EPA Science Inventory

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 quant...

236

MANGANESE--2002 49.1 By Lisa A. Corathers  

E-print Network

Materials Plan (AMP) for fiscal year 2003 that the Defense National Stockpile Center (DNSC) of the Defense available data suggest manganese is generally not considered toxic when ingested with the diet, and drinking resulting from a manganese deficiency in the diet. Manganese was one of nine constituents on the Contaminant

Torgersen, Christian

237

Manganese Exposure from Welding: An Emerging Liability Risk  

Microsoft Academic Search

In the 1930s, warnings began to appear cautioning welders about risks of neurological effects caused by manganese in fumes from welding. Since the early 1990s, litigation based on these effects has increased dramatically. The basic allegation is that fumes from manganese-alloy welding rods can produce Parkinsonism, a severe neurological condition similar to Parkinson's disease. Exposure to manganese produces symptoms such

John Wyckoff; Mark McBride

2004-01-01

238

Manganese-calcium clusters supported by calixarenes.  

PubMed

The structure of the oxygen-evolving complex of photosystem II, which contains a cubane-like metal-oxo cluster incorporating four manganese(III,IV) cations, along with a calcium cation, has focussed attention on synthetic analogues of this cluster. Despite this activity, there are relatively few structurally characterised coordination clusters with this combination of metal cations. The calixarenes are synthetically versatile and well established cluster-supporting ligands, which to date have not been reported to support a calcium/manganese cluster. Here we report that p-t-butylthiacalix[4]arene supports CaMn2 and Ca2Mn2 clusters, whereas reactions of p-t-butylcalix[4]arene, p-t-butylsulfinylcalix[4]arene, and p-t-butylsulfonylcalix[4]arene, under the same conditions, produced only homometallic manganese complexes. PMID:25500802

Fuller, Rebecca O; Koutsantonis, George A; Lozi?, Ivan; Ogden, Mark I; Skelton, Brian W

2015-01-20

239

Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor  

NASA Technical Reports Server (NTRS)

Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

Myers, Charles R.; Nealson, Kenneth H.

1988-01-01

240

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

NASA Astrophysics Data System (ADS)

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.

Danas, K.; Triantafyllidis, N.

2014-09-01

241

Rotating field eddy current probe for characterization of cracking in non-magnetic tubing  

SciTech Connect

A rotating field eddy current probe was built and tested for use in small diameter, non-magnetic tubing. The rotating field probe is a driver/pickup style with two orthogonally wound drive coils and a pancake pickup coil. The driver coils are excited by two sine waves 90{degree} out of phase with each other. The physical arrangement of the drive coils and the 90{degree} phase shift of the excitation waveforms creates a field which rotates in the test piece under the drive coils. Preliminary tests on electrical discharge machined (EDM) notches show that phased based estimates of notch depth are possible. Probes currently used for detection of cracks in tubing produce responses that have proven unreliable for estimating defect depths. This recently developed version of the rotating field eddy current probe produces a bipolar response in the presence of a crack or a notch. Typically, the phase angle of a bipolar eddy current response is easily identified and measured and is used extensively for estimating depths of volumetric defects. Data are shown relating the phase angle of the rotating field probe`s bipolar response to the depth of circumferential EDM notches.

Capobianco, T.E. [Lockheed Martin, Schenectady, NY (United States)

1998-07-01

242

Controlling magnetism on metal surfaces with non-magnetic means: electric fields and surface charging.  

PubMed

We review the state of the art of surface magnetic property control with non-magnetic means, concentrating on metallic surfaces and techniques such as charge-doping or external electric field (EEF) application. Magneto-electric coupling via EEF-based charge manipulation is discussed as a way to tailor single adatom spins, exchange interaction between adsorbates or anisotropies of layered systems. The mechanisms of paramagnetic and spin-dependent electric field screening and the effect thereof on surface magnetism are discussed in the framework of theoretical and experimental studies. The possibility to enhance the effect of EEF by immersing the target system into an electrolyte or ionic liquid is discussed by the example of substitutional impurities and metallic alloy multilayers. A similar physics is pointed out for the case of charge traps, metallic systems decoupled from a bulk electron bath. In that case the charging provides the charge carrier density changes necessary to affect the magnetic moments and anisotropies in the system. Finally, the option of using quasi-free electrons rather than localized atomic spins for surface magnetism control is discussed with the example of Shockley-type metallic surface states confined to magnetic nanoislands. PMID:24523356

Brovko, Oleg O; Ruiz-Díaz, Pedro; Dasa, Tamene R; Stepanyuk, Valeri S

2014-03-01

243

Revealing the Degree of Magnetic Frustration by Non-Magnetic Impurities  

SciTech Connect

Imaging the magnetic fields around a non-magnetic impurity can provide a clear benchmark for quantifying the degree of magnetic frustration. Focusing on the strongly frustrated J{sub 1}-J{sub 2} model and the spatially anisotropic J{sub 1a}-J{sub 1b}-J{sub 2} model, very distinct low energy behaviors reflect different levels of magnetic frustration. In the J{sub 1}-J{sub 2} model, bound magnons appear trapped near the impurity in the ground state and strongly reduce the ordered moments for sites proximal to the impurity. In contrast, local moments in the J{sub 1a}-J{sub 1b}-J{sub 2} model are enhanced on the impurity neighboring sites. These theoretical predictions can be probed by experiments such as nuclear magnetic resonance and scanning tunneling microscopy, and the results can elucidate the role of frustration in antiferromagnets and help narrow the possible models to understand magnetism in the iron pnictdies.

Not Available

2011-08-12

244

Are non-magnetic mechanisms such as temporal solar diameter variations conceivable for an irradiance variability?  

E-print Network

Irradiance variability has been monitored from space for more than two decades. Even if data are coming from different sources, it is well established that a temporal variability exists which can be set to as approximately 0.1%, in phase with the solar cycle. Today, one of the best explanation for such an irradiance variability is provided by the evolution of the solar surface magnetic fields. But if some 90 to 95% can be reproduced, what would be the origin of the 10 to 5% left? Non magnetic effects are conceivable. In this paper we will consider temporal variations of the diameter of the Sun as a possible contributor for the remaining part. Such an approach imposes strong constraints on the solar radius variability. We will show that over a solar cycle, variations of no more than 20 mas of amplitude can be considered. Such a variability (far from what is reported by observers conducting measurements by means of ground-based solar astrolabes) may explain a little part of the irradiance changes not explained by magnetic features. Further requirements are needed that may help to reach a conclusion. Dedicated space missions are necessary (for example PICARD, GOLF-NG or SDO, scheduled for a launch around 2008); it is also proposed to reactivate SDS flights for such a purpose.

J. P. Rozelot; S. Lefebvre; S. Pireaux; A. Ajabshirizadeh

2006-01-05

245

Manganese concentrations in Scottish groundwater.  

PubMed

Groundwater is increasingly being used for public and private water supplies in Scotland, but there is growing evidence that manganese (Mn) concentrations in many groundwater supplies exceed the national drinking water limit of 0.05 mg l(-1). This study examines the extent and magnitude of high Mn concentrations in groundwater in Scotland and investigates the factors controlling Mn concentrations. A dataset containing 475 high quality groundwater samples was compiled using new data from Baseline Scotland supplemented with additional high quality data where available. Concentrations ranged up to 1.9 mg l(-1); median Mn concentration was 0.013 mg l(-1) with 25th and 75th percentiles 0.0014 and 0.072 mg l(-1) respectively. The Scottish drinking water limit (0.05 mg l(-1)) was exceeded for 30% of samples and the WHO health guideline (0.4 mg l(-1)) by 9%; concentrations were highest in the Carboniferous sedimentary aquifer in central Scotland, the Devonian sedimentary aquifer of Morayshire, and superficial aquifers. Further analysis using 137 samples from the Devonian aquifers indicated strong redox and pH controls (pH, Eh and dissolved oxygen accounted for 58% of variance in Mn concentrations). In addition, an independent relationship between Fe and Mn was observed, suggesting that Fe behaviour in groundwater may affect Mn solubility. Given the redox status and pH of Scottish groundwaters the most likely explanation is sorption of Mn to Fe oxides, which are released into solution when Fe is reduced. Since the occurrence of elevated Mn concentrations is widespread in groundwaters from all aquifer types, consideration should be given to monitoring Mn more widely in both public and private groundwater supplies in Scotland and by implication elsewhere. PMID:20219236

Homoncik, Sally C; Macdonald, Alan M; Heal, Kate V; Dochartaigh, Brighid E O; Ngwenya, Bryne T

2010-05-15

246

Fracture in ceramic-reinforced metal matrix composites based on high-speed steel  

Microsoft Academic Search

A series of metal matrix composites based upon M3\\/2 high-speed steel was produced by a powder metal sintering route. Hard ceramic titanium carbide or niobium carbide additions and a self-lubricant in the form of manganese sulfide, were added as a basis for achieving improved wear resistance and reduced friction. After sintering, the composites were given a full standard high-speed steel

J. D BOLTON; A. J GANT

1998-01-01

247

Effect of Steel Converter Sludge as Iron Fertilizer and Soil Amendment in Some Calcareous Soils  

Microsoft Academic Search

The possibility of using converter sludge, a steel factory by-product, as an iron (Fe) fertilizer and amendment in some calcareous soils was investigated. This compound contains 64% Fe oxides plus large amounts of some other elements such as calcium (Ca), silicon (Si), manganese (Mn), phosphorus (P), and potassium (K). Different mixtures of converter sludge with sulfuric acid, organic matter and

A. Abbaspour; M. Kalbasi; H. Shariatmadari

2005-01-01

248

Influence of oxide inclusions of the mechanical properties of steel with a low carbon content  

Microsoft Academic Search

The influence of the area occupied by inclusions on the mechanical properties of steel with deoxidation of molten commercially pure iron with aluminum, silicon, manganese, and mixtures of them was determined. A chemical analysis of the inclusions was made. The investigation data was processed mathematically. The influence of heat treatment on the composition of the inclusions was shown. 2 refs.,

I. B. Gutovskii; V. I. Bodnarchuk; V. G. Kochkin; V. A. Kolchanov

1992-01-01

249

Manganese regulation of manganese peroxidase expression and lignin degradation by the white rot fungus Dichomitus squalens.  

PubMed Central

Extracellular manganese peroxidase and laccase activities were detected in cultures of Dichomitus squalens (Polyporus anceps) under conditions favoring lignin degradation. In contrast, neither extracellular lignin peroxidase nor aryl alcohol oxidase activity was detected in cultures grown under a wide variety of conditions. The mineralization of 14C-ring-, -side chain-, and -methoxy-labeled synthetic guaiacyl lignins by D. squalens and the expression of extracellular manganese peroxidase were dependent on the presence of Mn(II), suggesting that manganese peroxidase is an important component of this organism's lignin degradation system. The expression of laccase activity was independent of manganese. In contrast to previous findings with Phanerochaete chrysosporium, lignin degradation by D. squalens proceeded in the cultures containing excess carbon and nitrogen. PMID:1768094

Périé, F H; Gold, M H

1991-01-01

250

The manganese site of the photosynthetic water-splitting enzyme  

SciTech Connect

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 (S{sub 1}) 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. 24 refs., 2 figs., 1 tab.

George, G.N.; Prince, R. (Exxon Research and Engineering Co., Annandale, NJ (USA)); Cramer, S.P. (Schlumberger-Doll Research, Ridgefield, CT (USA))

1989-02-10

251

Non-magnetic Iron Rich Microspherules from Younger Dryas Boundary Layer  

NASA Astrophysics Data System (ADS)

We report the discovery of abundance peaks of high-temperature non-magnetic spherules at 3 sites that date at or close to the onset of the Younger Dryas (YD) cooling episode at 12.9 ± 0.1 kiloannum. Two sites (Gainey and Blackwater Draw) exhibit human cultural artifact sequences that rank them among the premier end-Pleistocene archeological locations. The third site has been discovered in southern part of Czech Republic within the sedimentary record of paleolake Svarcenberk. The spherules, sometimes associated with high temperature melt-glass, are found in the Younger Dryas boundary (YDB) layer proposed to have resulted from a cosmic impact/airburst (Firestone et al., 2007). That event was posited to have triggered Younger Dryas cooling, contributed to megafaunal extinctions, and led to human cultural shifts and population decreases across the Northern Hemisphere. Reports of peak abundances in YDB impact-related spherules have been confirmed by several independent groups, but disputed by several others. We have performed geochemical analyses with energy dispersive x-ray spectroscopy on YDB spherules, supported by examination of surface ultrastructures by scanning electron microscope. These analyses demonstrate that the spherules were not formed through volcanic, cosmic, anthropogenic, biogenic, or authigenic processes. Instead, they are comprised of high-temperature mineral phases of terrestrial source rocks and sediments. They are also geochemically similar to spherules, melted glass tektites, and impact ejecta recovered from twelve known impact craters and strewnfields, including the Australasian tektite field (780 kiloannum) and the Cretaceous-Paleogene impact layer (65 million years), supporting the hypothesis that they formed by cosmic impact. Magnetic analyses performed on spherules allowed separation of microspherules into two groups. Group A with enhanced coercivity corresponds to microspheres composed of nanosphere agglomerates with high silica content. Group B with low susceptibility corresponds to crystallized microspheres. Magnetic signature of both groups show that their genesis is not connected with lightning discharge and rather confirms magnetization in ambient geomagnetic field.

Kletetschka, G.; Nabelek, L.; Svitavska-Sokolova, H.; Kadlec, J.; Bunch, T. E.; West, A.; Firestone, R. B.

2013-05-01

252

Soil Manganese Enrichment from Industrial Inputs: A Gastropod Perspective  

PubMed Central

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

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

2014-01-01

253

Soil manganese enrichment from industrial inputs: a gastropod perspective.  

PubMed

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

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

2014-01-01

254

Metallurgy and Processing of Marine Manganese Nodules  

Microsoft Academic Search

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

D. W. FUERSTENAU; K. N. HAN

1983-01-01

255

Risk Assessment of an Essential Element: Manganese  

Microsoft Academic Search

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

Annette B. Santamaria; Sandra I. Sulsky

2010-01-01

256

Lattice effects in magnetoresistive manganese perovskites  

Microsoft Academic Search

The discovery of spectacularly large magnetoresistive responses in a class of metallic manganese oxides has raised hopes that these compounds might be of practical utility. But regardless of whether this promise is realized, these materials provide an ideal system in which to elucidate the properties of metals in which electron–lattice interactions play a key role.

A. J. Millis

1998-01-01

257

BORON, MANGANESE, MOLYBDENUM, AND OTHER TRACE ELEMENTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The nutritional importance of each of the mineral elements reviewed in this chapter is considered limited, unclear, or speculative. Three elements can be considered essential for higher animals and humans. These elements are manganese and molybdenum, which are known enzyme cofactors, and boron, whos...

258

ADVERSE HEALTH EFFECTS FROM ENVIRONMENTAL MANGANESE EXPOSURE.  

EPA Science Inventory

The ubiquitous element, manganese (Mn), is an essential nutrient, but toxic at excessive exposure levels. Therefore, the US EPA set guideline levels for Mn exposure through inhalation (reference concentration-RfC=0.05 ?g/m3) and ingestion (reference dose-RfD=0.14 mg/kg/day (10 mg...

259

Manganese binding proteins in human and cow's milk  

SciTech Connect

Manganese nutrition in the neonatal period is poorly understood, due in part to a lack of information on the amount of manganese in infant foods and its bioavailability. Since the molecular localization of an element in foods is one determinant of its subsequent bioavailability, a study was made of the binding of manganese in human and cow's milk. An extrinsic label of /sup 54/Mn was shown to equilibrate isotopically with native manganese in milks and formulas. Milk samples were separated into fat, casein and whey by ultracentrifugation. In human milk, the major part (71%) of manganese was found in whey, 11% in casein and 18% in the lipid fraction. In contrast, in cow's milk, 32% of total manganese was in whey, 67% in casein and 1% in lipid. Within the human whey fraction, most of the manganese was bound to lactoferrin, while in cow's whey, manganese was mostly complexed to ligands with molecular weights less than 200. The distribution of manganese in formulas was closer to that of human milk than of cow's milk. The bioavailability of manganese associated with lactoferrin, casein and low molecular weight complexes needs to be assessed.

Loennerdal, B.; Keen, C.L.; Hurley, L.S.

1985-03-01

260

Oxidative stress involves in astrocytic alterations induced by manganese.  

PubMed

It is hypothesized that manganese neurotoxicity could be secondary to a diminution of cellular protective and scavenger mechanisms. Since manganese is known to be sequestered in glial cells, we investigated possible neurotoxic mechanisms involving astrocytes in vitro. Astrocytes differentiated into process-bearing stellate cells in response to manganese treatment. Manganese concentration dependently decreased cellular DNA synthesis, glial fibrillary acidic protein expression, energy production, antioxidant capacity, and glutamate transporter activity. In contrast, manganese increased glutamine synthetase protein expression and cytokine-stimulated interleukin 6 mRNA expression. Under the concentration of 0.1 mM, manganese chloride caused no significant astrocyte death even up to 48 h after treatment. That is, these astrocytic alterations proceeded before the onset of cell demise. As a possible mediator of manganese-derived alterations, we determined intracellular redox state in astrocytes. Manganese time-dependently changed intracellular redox potential into oxidized state. The influx of manganese and its resultant oxidative stress was essential to most of the alterations, except for the action on stellation. Astrocytes are central component of the brain's antioxidant defense. Therefore, the observations suggest that dysfunction of astrocytes possibly involved in neurotoxic action of manganese. PMID:12009774

Chen, Chun-Jung; Liao, Su-Lan

2002-05-01

261

Anodic Behaviour of High Nitrogen-Bearing Steel in PEMFC Environments  

SciTech Connect

High nitrogen-bearing stainless steels, AISI Type 201 and AL219, were investigated in simulated polymer electrolyte membrane fuel cell (PEMFC) environments to assess the use of these materials in fuel cell bipolar plate applications. Both steels exhibit better corrosion behavior than 316L steel in the same environments. Type 201 steel shows similar but lower interfacial contact resistance (ICR) than 316L, while AL219 steel shows higher ICR than 316L. X-ray photoelectron spectroscopy (XPS) analysis shows that the air-formed films on Type 201 and AL219 are composed of iron oxides, chromium oxide, and manganese oxide. Iron oxides dominate the composition of the air-formed film, specially the outer layer. Chromium oxide dominates passive films. Surface film thicknesses were estimated. The results suggest that high nitrogen-bearing stainless steels are promising materials for PEMFC bipolar plates.

Wang, H.; Turner, J. A.

2008-02-01

262

The nature of the velocity field in molecular clouds - I. The non-magnetic case  

NASA Astrophysics Data System (ADS)

We present numerical simulations designed to test some of the hypotheses and predictions of recent models of star formation. We consider a set of three numerical simulations of randomly driven, isothermal, non-magnetic, self-gravitating turbulence with different rms Mach numbers Ms and physical sizes L, but with approximately the same value of the virial parameter, ? ~ 1.2. We obtain the following results: (i) we test the hypothesis that the collapsing centres originate from locally Jeans unstable (`super-Jeans'), subsonic fragments; we find no such structures in our simulations, suggesting that collapsing centres can arise also from regions that have supersonic velocity dispersions but are nevertheless gravitationally unstable. (ii) We find that the fraction of small-scale super-Jeans structures is larger in the presence of self-gravity. (iii) There exists a trend towards more negative values of the velocity field's mean divergence in regions with higher densities, implying the presence of organized inflow motions within the structures analysed. (iv) The density probability density function (PDF) deviates from a lognormal in the presence of self-gravity, developing an approximate power-law high-density tail, in agreement with previous results. (v) Turbulence alone in the large-scale simulation (L = 9 pc) does not produce regions with the same size and mean density as those of the small-scale simulation (L = 1 pc). Items (ii)-(v) suggest that self-gravity is not only involved in causing the collapse of Jeans-unstable density fluctuations produced by the turbulence, but also in their formation. We then measure the `star formation rate per free-fall time', SFRff, as a function of Ms for the three runs, and compare with the predictions of recent semi-analytical models. We find marginal agreement to within the uncertainties of the measurements. However, within the L = 9 pc simulation, subregions with similar density and size to those of the L = 1 pc simulation differ qualitatively from the latter in that they exhibit a global convergence of the velocity field ?.v ~ -0.6kms-1 pc-1 on average. This suggests that the assumption that turbulence in clouds and clumps is purely random is incomplete. We conclude that (i) part of the observed velocity dispersion in clumps must arise from clump-scale inwards motions, even in driven-turbulence situations, and (ii) analytical models of clump and star formation need to take into account this dynamical connection with the external flow and the fact that, in the presence of self-gravity, the density PDF may deviate from a lognormal.

Vázquez-Semadeni, Enrique; González, Ricardo F.; Ballesteros-Paredes, Javier; Gazol, Adriana; Kim, Jongsoo

2008-10-01

263

VizieR Online Data Catalog: STEREO non-magnetic chemically peculiar stars (Paunzen+, 2013)  

NASA Astrophysics Data System (ADS)

We have analysed the photometric data obtained with the STEREO spacecraft for 558 non-magnetic chemically peculiar (CP) stars to search for rotational and pulsational variability. Applying the Lomb-Scargle and the phase dispersion minimization methods, we have detected photometric variability for 44 objects from which 35 were previously unknown. The new objects are all bright stars on the ecliptic plane (magnitude range 4.7

Paunzen, E.; Wraight, K. T.; Fossati, L.; Netopil, M.; White, G. J.; Bewsher, D.

2014-03-01

264

Manganese nutrition in rat and swine reproduction.  

E-print Network

??Experiments were conducted with littermate gilts maintained in stainless steel metabolism cages within environmentally controlled rooms and consuming a corn-soybean meal based diet. The objectives… (more)

Rhéaume, John

1990-01-01

265

Microstructure and mechanical behavior of neutron irradiated ultrafine grained ferritic steel  

SciTech Connect

Neutron irradiation effects on ultra-fine grain (UFG) low carbon steel prepared by equal channel angular pressing (ECAP) has been examined. Counterpart samples with conventional grain (CG) sizes have been irradiated alongside with the UFG ones for comparison. Samples were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) to 1.24 dpa. Atom probe tomography revealed manganese, silicon-enriched clusters in both ECAP and CG steel after neutron irradiation. X-ray quantitative analysis showed that dislocation density in CG increased after irradiation. However, no significant change was observed in UFG steel revealing better radiation tolerance.

Ahmad Alsabbagh; Apu Sarkar; Brandon Miller; Jatuporn Burns; Leah Squires; Douglas Porter; James I. Cole; K. L. Murty

2014-10-01

266

Biomineralisation of manganese on titanium surfaces exposed to seawater.  

PubMed

A 2-year long study was carried out to isolate and characterise various bacterial species present in the biofilm formed on titanium surfaces exposed to seawater and to assess the manganese oxidizing potential of the marine isolates. The amount of manganese present in the biofilm was also measured using atomic absorption spectrometry (AAS). The results showed that titanium was susceptible to biofouling. More than 50% of the culturable marine bacterial isolates were capable of bringing about oxidation of Mn(II). All these manganese oxidizing bacteria were heterotrophic. Autotrophic manganese oxidizing bacteria such as Leptothrix was not isolated in the present study. The AAS results confirmed that the manganese content in the biofilms increased with increasing exposure time. Hence, the study indicates that the titanium surfaces when exposed to seawater were colonised by a large number of heterotrophic bacteria, which have the ability of bringing about biomineralisation of manganese. PMID:18568665

Gopal, Judy; Muraleedharan, P; Sarvamangala, H; George, R P; Dayal, R K; Tata, B V R; Khatak, H S; Natarajan, K A

2008-01-01

267

40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).  

...2014-07-01 2014-07-01 false Cobalt iron manganese oxide, carboxylic acid-modified...Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid-modified...substance identified generically as cobalt iron manganese oxide, carboxylic...

2014-07-01

268

40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Cobalt iron manganese oxide, carboxylic acid-modified...Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid-modified...substance identified generically as cobalt iron manganese oxide, carboxylic...

2013-07-01

269

40 CFR 424.60 - Applicability; description of the electrolytic manganese products subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the electrolytic manganese products subcategory. 424.60 Section...POINT SOURCE CATEGORY Electrolytic Manganese Products Subcategory § 424.60 ...Applicability; description of the electrolytic manganese products subcategory. The...

2010-07-01

270

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

Federal Register 2010, 2011, 2012, 2013

...731-TA-1124 and 1125 (Review)] Electrolytic Manganese Dioxide From Australia and China; Institution...antidumping duty orders on electrolytic manganese dioxide from Australia and China would...duty orders on imports of electrolytic manganese dioxide from Australia and China...

2013-09-03

271

75 FR 70665 - Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide  

Federal Register 2010, 2011, 2012, 2013

...Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide AGENCY...for the chemical substance identified as cobalt lithium manganese nickel oxide (CAS No...for the chemical substance identified as cobalt lithium manganese nickel oxide...

2010-11-18

272

Plutonium(VI) sorption to manganese dioxide.  

SciTech Connect

Redox-active metal oxides may strongly affect the environmental behavior and mobility of actinides . Manganese oxides are relatively common redox-active soil components, which have a high surface area and which some studies show sorb plutonium selectively over other mineral phases .' For plutonium, oxidation states that could exist in the environment include +111 to +VI, with Pu(IV) being predominant in the insoluble phase. Plutonium(V), and to a lesser extent Pu(VI), are the stable Pu oxidation states in solution under environmental conditions .Z We are using synthetic 6-Mn02 because it is most similar to the common natural manganese oxide mineral birnessite . Previously, we have shown that Pu(V) is oxidized to Pu(VI) in solution by 8-Mn02, then very effectively sorbed to the mineral . We are now studying Pu(VI) sorption to synthetic 8-Mn02 in detail to determine its sorption mechanisms and sorption capacity .

Reilly, S. D. (Sean D.); Myers, W. K. (William K.); Stout, S. A. (Stephen A.); Smith, D. M. (Donna M.); Ginder-Vogel, M. A. (Matthew A.); Neu, M. P. (Mary P.)

2003-01-01

273

International Strategic Minerals Inventory summary report; manganese  

USGS Publications Warehouse

Major world resources of manganese, a strategic mineral commodity, are described in this summary report of information in the International Strategic Minerals Inventory {ISMI). ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of manganese on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

DeYoung, John H.; Sutphin, David M.; Cannon, William F.

1984-01-01

274

Manganese enhanced MRI (MEMRI): neurophysiological applications  

PubMed Central

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

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

2012-01-01

275

Dietary manganese requirement of P. Vannamei  

NASA Astrophysics Data System (ADS)

Graded levels of manganese were supplemented to a semi-purified diet containing 45% crude protein, to provide six levels of manganese (i. e. containing 5, 25, 50, 70, 140 and 210×10-6, respectively) for two experiments with these experimental diets. The initial weight of shrimp used in the 35 day experiment I was 0.30±0.04 g, and that in the 70 day Experiment II was more than one gram. The results showed that optimum content in the semi-purified diet for the more than 1 gram shrimp ranged from 70 ×10-6, to 140×10-6, but supplementation of Mn was not necessary for the small shrimp.

Liu, Fa-Yi; Lawrence, A. L.

1997-06-01

276

Response of pigeon pea to variable levels of manganese  

Microsoft Academic Search

Pigeon pea (Cajanus cajan (L.) Millsp.) cv. T21 was grown in refined sand at manganese levels ranging from 0-0011 to 5·5 mg 1?1. At less than 0·055 mg Mn 1?1, growth was depressed. In manganese deficient plants, there was reduction in the area and number of leaves. A reduction in\\u000a seed yield was observed at low and excess manganese and

C P Sharma; Neena Khurana; C Chatterjee; S C Agarwala

1988-01-01

277

Terrestrial manganese-53 — A new monitor of Earth surface processes  

Microsoft Academic Search

We report the first systematic study of the terrestrial cosmogenic radionuclide manganese-53 (T1\\/2=3.7 Ma) measured in thirteen samples from nine dolerite surfaces in the Dry Valleys, Antarctica. The terrestrial manganese-53 concentrations correlate well with cosmic-ray-produced helium-3 and neon-21 concentrations in the same samples, implying that the manganese-53 is produced continuously in situ and retained quantitatively over millions of years. The terrestrial

Joerg M. Schaefer; Thomas Faestermann; Gregory F. Herzog; Klaus Knie; Gunther Korschinek; Jozef Masarik; Astrid Meier; Michail Poutivtsev; Georg Rugel; Christian Schlüchter; Feride Serifiddin; Gisela Winckler

2006-01-01

278

Manganese oxide nanowires, films, and membranes and methods of making  

DOEpatents

Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves and methods of making the same are disclosed. A method for forming nanowires includes hydrothermally treating a chemical precursor composition in a hydrothermal treating solvent to form the nanowires, wherein the chemical precursor composition comprises a source of manganese cations and a source of counter cations, and wherein the nanowires comprise ordered porous manganese oxide-based octahedral molecular sieves.

Suib, Steven Lawrence (Storrs, CT); Yuan, Jikang (Storrs, CT)

2011-02-15

279

Manganese Inhalation as a Parkinson Disease Model  

PubMed Central

The present study examines the effects of divalent and trivalent Manganese (Mn2+/Mn3+) mixture inhalation on mice to obtain a novel animal model of Parkinson disease (PD) inducing bilateral and progressive dopaminergic cell death, correlate those alterations with motor disturbances, and determine whether L-DOPA treatment improves the behavior, to ensure that the alterations are of dopaminergic origin. CD-1 male mice inhaled a mixture of Manganese chloride and Manganese acetate, one hour twice a week for five months. Before Mn exposure, animals were trained to perform motor function tests and were evaluated each week after the exposure. By the end of Mn exposure, 10 mice were orally treated with 7.5?mg/kg L-DOPA. After 5 months of Mn mixture inhalation, striatal dopamine content decreased 71%, the SNc showed important reduction in the number of TH-immunopositive neurons, mice developed akinesia, postural instability, and action tremor; these motor alterations were reverted with L-DOPA treatment. Our data provide evidence that Mn2+/Mn3+ mixture inhalation produces similar morphological, neurochemical, and behavioral alterations to those observed in PD providing a useful experimental model for the study of this neurodegenerative disease. PMID:21209715

Ordoñez-Librado, José Luis; Anaya-Martínez, Verónica; Gutierrez-Valdez, Ana Luisa; Colín-Barenque, Laura; Montiel-Flores, Enrique; Avila-Costa, Maria Rosa

2011-01-01

280

Manganese-Based Magnets: Manganese-Based Permanent Magnet with 40 MGOe at 200°C  

SciTech Connect

REACT Project: PNNL is working to reduce the cost of wind turbines and EVs by developing a manganese-based nano-composite magnet that could serve as an inexpensive alternative to rare-earth-based magnets. The manganese composite, made from low-cost and abundant materials, could exceed the performance of today’s most powerful commercial magnets at temperature higher than 200°C. Members of PNNL’s research team will leverage comprehensive computer high-performance supercomputer modeling and materials testing to meet this objective. Manganese-based magnets could withstand higher temperatures than their rare earth predecessors and potentially reduce the need for any expensive, bulky engine cooling systems for the motor and generator. This would further contribute to cost savings for both EVs and wind turbines.

None

2012-01-01

281

Deposition of manganese in a drinking water distribution system.  

PubMed Central

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

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

1990-01-01

282

Structural Characterization of Yttrium-Implanted Pure Iron and Steels Oxidized at High Temperature  

Microsoft Academic Search

Yttrium-implanted and unimplanted pure electrolytic iron, low-manganese and low-manganese–carbon steels were analyzed at high temperature (T=700°C) under oxygen partial pressure \\u000a$${\\\\text{P}}_{O_2 } = 0.04Pa$$\\u000a to observe their oxidation resistances. X-ray diffraction (XRD), reflected high-energy electron diffraction (RHEED), and glancing-angle X-ray diffraction (GAXRD) analyses performed on yttrium-implanted samples before high-temperature oxidation tests show that yttrium implantation promotes the formation of Y_2O_3,

E. Caudron; H. Buscail

2001-01-01

283

Textured non-magnetic Ni-V 10% alloy tape for epitaxial growth of high {Tc} superconductors  

SciTech Connect

The problem of developing non magnetic cube textured metallic substrates other than pure Ni, to be used for epitaxial deposition of Y-123 superconducting film (with an intermediate oxide buffer layer) is being tackled since three years by several laboratories. As reported in this paper, the authors have developed a new substrate, based on Ni-V 10 wt % alloy, which exhibits a cube texture comparable to Ni, but has a Curie temperature < 4.2 K; in addition, it has a hardness which is more than twice higher and a comparable oxidation resistance.

Ceresara, S. [Centro Innovazione Lecco (Italy)] [Centro Innovazione Lecco (Italy); Boffa, V.; Petrisor, T.; Fabbri, F. [ENEA, Roma (Italy). Centro Recerche Frascati] [ENEA, Roma (Italy). Centro Recerche Frascati; Scardi, P. [Univ. di Trento (Italy). Dipt. di Ingegneria dei Materiali] [Univ. di Trento (Italy). Dipt. di Ingegneria dei Materiali

1999-04-20

284

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

NASA Astrophysics Data System (ADS)

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.

Kiviö, Miia; Holappa, Lauri

2012-04-01

285

N-Lauroyl Sarcosine Sodium Salt as a Corrosion Inhibitor for Type 1518 Carbon Steel in Neutral Saline Environments  

Microsoft Academic Search

The influence of the sodium salt of N-lauroyl sarcosine (NLS) on corrosion of a manganese steel was studied in aerated, nearly neutral saline solutions at room temperature and under various hydrodynamic conditions. The inhibitive efficiency of NLS was examined using gravimetric tests, polarization curves, and electrochemical impedance spectroscopy (EIS). The additive slowed the corrosion phenomena, either generalized or localized, that

A. Frignani; C. Wrubl; A. Mollica; G. Trabanelli

1996-01-01

286

Low-activation Mn Cr austenitic stainless steel with further reduced content of long-lived radioactive elements  

NASA Astrophysics Data System (ADS)

Low-activation austenitic stainless steel based on Mn-Cr non-magnetic steels has been developed. The alloying elements of long-life activation, such as Ni, Mo and Co, were eliminated and substituted with Mn along with an addition of N. A Mn-Cr austenitic stainless steel, 24.5Mn-13.5Cr-0.02C-0.2N, has been developed successfully. Examined material properties, including mechanical, thermal and magnetic properties, as well as weldability and characteristics of corrosion resistance, are presented. It was found that the alloy has excellent material properties virtually equivalent to those of 316SS. In this study, the applicability of the Schaeffler, DeLong and Hull constitution diagrams for the stainless steels with low Ni and high Mn contents was also examined. The boundary conditions distinguishing the single austenite phase from the others have been identified for the Mn-Cr steels.

Onozuka, Masanori; Saida, Tomikane; Hirai, Shouzou; Kusuhashi, Mikio; Sato, Ikuo; Hatakeyama, Tsuyoshi

1998-06-01

287

Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria  

PubMed Central

Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 106 acetate-utilizing manganese-reducing cells cm?3 in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

2012-01-01

288

Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.  

PubMed

Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

2012-11-01

289

Available manganese oxides in neutral and alkaline soils  

Microsoft Academic Search

Summary The available higher oxides of manganese in neutral and alkaline soils are estimated by first treating with alcoholic quinol, then washing with alcohol, and finally extracting with semi-molar calcium nitrate. Healthy soils contain from 20 to 50 p.p.m. of manganese so extractable.

L. H. P. Jones; G. W. Leeper

1951-01-01

290

Manganese-enhanced magnetic resonance microscopy of mineralization  

Microsoft Academic Search

Paramagnetic manganese (II) can be employed as a calcium surrogate to sensitize magnetic resonance microscopy (MRM) to the processing of calcium during bone formation. At high doses, osteoblasts can take up sufficient quantities of manganese, resulting in marked changes in water proton T1, T2 and magnetization transfer ratio values compared to those for untreated cells. Accordingly, inductively coupled plasma mass

Ingrid E. Chesnick; Todor I. Todorov; Jose A. Centeno; Dale E. Newbury; John A. Small; Kimberlee Potter

2007-01-01

291

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2.  

E-print Network

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2. Results from X-ray Absorption September 23, 2010. Accepted October 1, 2010. Arsenite (AsIII ) oxidation by manganese oxides (Mn-oxides) servestodetoxifyand,undermanyconditions,immobilizearsenic (As) by forming arsenate (AsV ). AsIII oxidation by Mn

Sparks, Donald L.

292

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1.  

E-print Network

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1. Stirred-Flow Experiments B R A N D O September 23, 2010. Accepted October 1, 2010. Manganese-oxides (Mn-oxides) are quite reactive, with respect to arsenite (AsIII ) oxidation. However, studies regarding the pathways of AsIII oxidation, over a range

Sparks, Donald L.

293

Deep impurity levels and diffusion coefficient of manganese in silicon  

NASA Astrophysics Data System (ADS)

Manganese-related deep levels in n- and p-type silicon have been investigated by deep level transient spectroscopy and Hall effect. Two electron traps of Ec-(0.12±0.01) eV and Ec-(0.41±0.01) eV, and a hole trap of Ev+(0.32±0.01) eV are found in manganese-doped silicon. The energy levels of these traps correspond to the transitions between four charge states (Mn-, Mn0, Mn+, Mn++ ) of interstitial manganese. An additional donor-type electron trap of Ec-(0.51±0.02) eV is observed in the n-type samples, and the trap can be tentatively assigned to substitutional manganese. Furthermore, an electron trap of Ec-(0.50±0.02) eV is observed for n+p junction samples diffused with manganese in boron-doped p-type silicon. The trap is attributed to the manganese-boron complex, which is formed owing to the pairing reaction of interstitial manganese and substitutional boron. From the investigation of the pairing reaction, the diffusion coefficient DMn of interstitial manganese is determined in the temperature range 14-90 °C. It can be represented by the expression DMn=2.4×10-3 exp(-0.72/kT)cm2 s-1.

Nakashima, H.; Hashimoto, K.

1991-02-01

294

Formation of manganese oxides by bacterially generated superoxide  

NASA Astrophysics Data System (ADS)

Manganese oxide minerals are among the strongest sorbents and oxidants in the environment. The formation of these minerals controls the fate of contaminants, the degradation of recalcitrant carbon, the cycling of nutrients and the activity of anaerobic-based metabolisms. Oxidation of soluble manganese(II) ions to manganese(III/IV) oxides has been primarily attributed to direct enzymatic oxidation by microorganisms. However, the physiological reason for this process remains unknown. Here we assess the ability of a common species of marine bacteria-Roseobacter sp. AzwK-3b-to oxidize manganese(II) in the presence of chemical and biological inhibitors. We show that Roseobacter AzwK-3b oxidizes manganese(II) by producing the strong and versatile redox reactant superoxide. The oxidation of manganese(II), and concomitant production of manganese oxides, was inhibited in both the light and dark in the presence of enzymes and metals that scavenge superoxide. Oxidation was also inhibited by various proteases, enzymes that break down bacterial proteins, confirming that the superoxide was bacterially generated. We conclude that bacteria can oxidize manganese(II) indirectly, through the enzymatic generation of extracellular superoxide radicals. We suggest that dark bacterial production of superoxide may be a driving force in metal cycling and mineralization in the environment.

Learman, D. R.; Voelker, B. M.; Vazquez-Rodriguez, A. I.; Hansel, C. M.

2011-02-01

295

Pwave Pairing and Colossal Magnetoresistance in Manganese Oxides  

E-print Network

P­wave Pairing and Colossal Magnetoresistance in Manganese Oxides Yong­Jihn Kim y Department understood in terms of the p­wave pairing. In addition, colossal magnetoresistance (CMR) is natu­ rally paid to the manganese oxides since the observa­ tion of colossal magnetoresistance (CMR). 1\\Gamma4

296

MANGANESE--1997 49.1 By Thomas S. Jones  

E-print Network

production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking a variety of other uses, manganese is a key component of certain widely used aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature of manganese use in the United States

Torgersen, Christian

297

[Possible use of new corrosion-resistant steels in the manufacture of medical instruments].  

PubMed

Demands on metals intended for the manufacture of medical instruments call for the use of corrosion-resisting grades of steel with high strength characteristics. Grades of steel of the martensite class reinforced by age hardening (martensive-aging) and mild grades of steel (chrome-manganese and chrome-nickel) have a number of valuable advantages over the steel of other classes. The possibility of obtaining high strength with low carbon dontent ensures great plasticity, toughness and brittle failure resistance along with corrosion-resistance and the possibility of achieving a substantial simplification in technology of making the instruments. Investigations of martensite-aging grades of steel--ep832,ochX11H9M2d2Tyu, O3X11HMd2yu and O3X13g3Md2 demostrated them to hold good promise for the manufacture of surgical and atraumatic needles, and rod-type stomatological instruments. PMID:642760

Birman, S R; Starozhitski?, M I; Kuznetsov, A M

1978-01-01

298

AmiiSteele  

Cancer.gov

Skip to Main Content Headlines Pediatric Oncology Branch Home > Pediatric Psycho-Oncology Professionals > Profiles > Amii Steele Headline Title Pediatric Psycho-Oncology Professionals Amii Corbisiero Steele Amii Steele First Name:Amii  Last Name:

299

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

PubMed

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

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

2008-06-01

300

Treatability of manganese by sodium silicate and chlorine  

SciTech Connect

Manganese sequestering by nearly simultaneous additions of sodium silicate and sodium hypochlorite was studied in laboratory-prepared waters. Under conditions of near-neutral pH and 150-250 mg/liter of alkalinity as CaCO{sub 3}, 1-2 mg manganese/liter could be sequestered for up to one day. Less effective manganese treatability was found at pH 8 than at pH 7. Additionally, at pH 7 the best results were obtained when neither silicate nor hypochlorite was added because of the slow manganese oxidation rate by oxygen alone. Aging of diluted stock silicate solutions prior to dosing also resulted in poor treatment; the presence of background silica increased the treatment effectiveness only slightly. Overall, manganese was less treatable by this method than iron under the same treatment conditions.

Robinson, F.B.; Ronk, S.K. (Tennessee Univ., Knoxville (USA))

1987-11-01

301

Manganese Dependent Anaerobic Oxidation of Methane  

NASA Astrophysics Data System (ADS)

Understanding the anaerobic oxidation is not only important for understanding hydrocarbon degradation but it also important for understanding the global carbon cycle. The anaerobic oxidation of methane (AOM) is a large sink for methane consuming 5-20% of today's methane flux (Valentine and Reeburgh, 2000), yet the requirements for this process are not well understood. It has been suggested that no other electron acceptors other than sulfate can be used in the AOM (Nauhaus, 2005). However, our new data suggests that manganese, in the form of birnessite, can be used as an electron acceptor instead of sulfate (Beal et al., in prep). Methane seep sediment from the Eel River Basin, CA was incubated with methane, 13C-labeled methane, and carbon dioxide. Because the net result of the AOM is the production of carbon dioxide from methane, the rate of the AOM in each of the incubations can be determined by measuring the incorporation of 13C in the carbon dioxide. Using this method, it was found that cultures incubated with nitrate showed inhibition of the AOM, while cultures incubated with iron gave inconclusive results. The only positive results that were found for alternate electron acceptors are the incubations that were given manganese and no sulfate, which showed methane oxidation. Further, when more manganese was injected into these incubations, the rate of AOM increased. Preliminary analysis of the microbial population using terminal restriction fragment length polymorphism (TRFLP) targeting the mcr gene showed an unidentified organism in these cultures. Future work with TRFLP, as well as clone libraries, will help to identify the organisms responsible for this process. Nauhaus, K., 2005, Environmental regulation of the anaerobic oxidation of methane: a comparison of ANME-I and ANME-II communities: Environmental microbiology, v. 7, p. 98. Valentine, D.L., and Reeburgh, W.S., 2000, New perspectives on anaerobic methane oxidation: Environmental Microbiology, v. 2, p. 477-484.

Beal, E.; House, C.

2007-12-01

302

Manganese accumulation in the brain: MR imaging.  

PubMed

Manganese (Mn) accumulation in the brain is detected as symmetrical high signal intensity in the globus pallidi on T1-weighted MR images without an abnormal signal on T2-weighted images. In this review, we present several cases of Mn accumulation in the brain due to acquired or congenital diseases of the abdomen including hepatic cirrhosis with a portosystemic shunt, congenital biliary atresia, primary biliary cirrhosis, congenital intrahepatic portosystemic shunt without liver dysfunction, Rendu-Osler-Weber syndrome with a diffuse intrahepatic portosystemic shunt, and patent ductus venosus. Other causes of Mn accumulation in the brain are Mn overload from total parenteral nutrition and welding-related Mn intoxication. PMID:17624522

Uchino, A; Noguchi, T; Nomiyama, K; Takase, Y; Nakazono, T; Nojiri, J; Kudo, S

2007-09-01

303

Toxicity of manganese metallodrugs toward Danio rerio.  

PubMed

Manganese is an essential metal which can be neurotoxic in some instances. As Mn-based metallodrugs are ever more prevalent in clinical practice, concern regarding the toxic effects of Mn discharges to water bodies on the biota prompted us to study the physicochemical parameters of these complexes and to assess their acute toxicity toward adult Danio rerio individuals, particularly in terms of brain tissue damage. Our results show that the Mn(III)-salen acetate complex EUK108 is toxic, which can be rationalized in terms of its lipophilicity, stability and redox activity. PMID:23916747

Arndt, Anderson; Borella, Maria Inês; Espósito, Breno Pannia

2014-02-01

304

Development of Lymantria dispar affected by manganese in food.  

PubMed

We studied the response of gypsy moth (Lymantria dispar (Linnaeus) (Lepidoptera: Lymantriidae)) to the content of manganese in food in the laboratory breeding of caterpillars. The food of the caterpillars {Betula pendula Roth (Fagales: Betulaceae) leaves} was contaminated by dipping in the solution of MnCl2 · 4H2O with manganese concentrations of 0, 0.5, 5 and 10 mg ml(-1), by which differentiated manganese contents (307; 632; 4,087 and 8,124 mg kg(-1)) were reached. Parameters recorded during the rearing were as follows: effect of manganese on food consumption, mortality and length of the development of caterpillars, pupation and hatching of imagoes. At the same time, manganese concentrations were determined in the offered and unconsumed food, excrements, and exuviae of the caterpillars, pupal cases and imagoes by using the AAS method. As compared with the control, high manganese contents in the food of gypsy moth caterpillars affected the process of development particularly by increased mortality of the first instar caterpillars (8 % mortality for caterpillars with no Mn contamination (T0) and 62 % mortality for subjects with the highest contamination by manganese (T3)), by prolonged development of the first-third instar (18.7 days (T0) and 27.8 days (T3)) and by increased food consumption of the first-third instar {0.185 g of leaf dry matter (T0) and 0.483 g of leaf dry matter (T3)}. The main defence strategy of the caterpillars to prevent contamination by the increased manganese content in food is the translocation of manganese into frass and exuviae castoff in the process of ecdysis. In the process of development, the content of manganese was reduced by excretion in imagoes to 0.5 % of the intake level even at its maximum inputs in food. PMID:25028315

Kula, Emanuel; Martinek, Petr; Chromcová, Lucie; Hedbávný, Josef

2014-10-01

305

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

SciTech Connect

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.

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

1985-02-01

306

Investigation of methods for removal and recovery of manganese in hydrometallurgical processes  

Microsoft Academic Search

Manganese is a major impurity which needs to be removed in many hydrometallurgical processes while some waste solutions are also important secondary manganese sources. Precipitation methods were investigated for the removal and recovery of manganese from a typical nickel laterite waste solution.Hydroxide precipitation alone was not an attractive option for the recovery and removal of manganese to very low levels

Wensheng Zhang; Chu Yong Cheng; Yoko Pranolo

2010-01-01

307

Down-regulation of a manganese transporter in the face of metal toxicity.  

PubMed

The yeast Smf1p Nramp manganese transporter is posttranslationally regulated by environmental manganese. Smf1p is stabilized at the cell surface with manganese starvation, but is largely degraded in the vacuole with physiological manganese through a mechanism involving the Rsp5p adaptor complex Bsd2p/Tre1p/Tre2p. We now describe an additional level of Smf1p regulation that occurs with toxicity from manganese, but not other essential metals. This regulation is largely Smf1p-specific. As with physiological manganese, toxic manganese triggers vacuolar degradation of Smf1p by trafficking through the multivesicular body. However, regulation by toxic manganese does not involve Bsd2p/Tre1p/Tre2p. Toxic manganese triggers both endocytosis of cell surface Smf1p and vacuolar targeting of intracellular Smf1p through the exocytic pathway. Notably, the kinetics of vacuolar targeting for Smf1p are relatively slow with toxic manganese and require prolonged exposures to the metal. Down-regulation of Smf1p by toxic manganese does not require transport activity of Smf1p, whereas such transport activity is needed for Smf1p regulation by manganese starvation. Furthermore, the responses to manganese starvation and manganese toxicity involve separate cellular compartments. We provide evidence that manganese starvation is sensed within the lumen of the secretory pathway, whereas manganese toxicity is sensed within an extra-Golgi/cytosolic compartment of the cell. PMID:19369420

Jensen, Laran T; Carroll, Mark C; Hall, Matthew D; Harvey, Christopher J; Beese, Sara E; Culotta, Valeria C

2009-06-01

308

Manganese removal during bench-scale biofiltration.  

PubMed

As biological manganese (Mn) removal becomes a more popular water treatment technology, there is still a large gap in understanding the key mechanisms and range of operational characteristics. This research aimed to expand on previous bench-scale experiments by directly comparing small filtration columns inoculated with indigenous biofilms from a Mn filtration plant and filtration columns inoculated with a liquid suspension of Leptothrix discophora SP-6. Batch tests found that in the absence of manganese oxidizing bacteria Mn was not removed by air alone, whereas a mixed population and Leptothrix strain achieved greater than 90% removal of Mn. The bench-scale biofiltration experiments found that biological filters can be inoculated with a pure culture of L. discophora SP-6 and achieve a similar removal of indigenous biofilm. While Mn oxidizing bacteria (MOB) seem to be necessary for the auto-catalytic nature of these biological filters, Mn removal is achieved with a combination of adsorption to Mn oxides and biological oxidation. Additionally, it was demonstrated that biological Mn removal is possible over a broader "field of activity" (e.g., Mn removal occurred at a pH level as low as 6.5) than has previously been reported. The ability of this treatment technology to work over a broader range of influent conditions allows for more communities to consider biological treatment as an option to remove Mn from their drinking water. PMID:18809196

Burger, Mark S; Mercer, Stephen S; Shupe, Gordon D; Gagnon, Graham A

2008-12-01

309

Thermochemistry of iron manganese oxide spinels  

SciTech Connect

Oxide melt solution calorimetry has been performed on iron manganese oxide spinels prepared at high temperature. The enthalpy of formation of (Mn{sub x}Fe{sub 1-x}){sub 3}O{sub 4} at 298K from the oxides, tetragonal Mn{sub 3}O{sub 4} (hausmannite) and cubic Fe{sub 3}O{sub 4} (magnetite), is negative from x=0 to x=0.67 and becomes slightly positive for 0.670.6) spinels of intermediate compositions. The enthalpies of formation are discussed in terms of three factors: oxidation-reduction relative to the end-members, cation distribution, and tetragonality. A combination of measured enthalpies and Gibbs free energies of formation in the literature provides entropies of mixing. {delta}S{sub mix}, consistent with a cation distribution in which all trivalent manganese is octahedral and all other ions are randomly distributed for x>0.5, but the entropy of mixing appears to be smaller than these predicted values for x<0.4.

Guillemet-Fritsch, Sophie [Centre InterUniversitaire de Recherche et d'Ingenierie des Materiaux (CIRIMAT/LCMIE), Universite Paul Sabatier, Ba-hat timent 2R1, 118, route de Narbonne, 31062 Toulouse, Cedex 04 (France); Navrotsky, Alexandra [Thermochemistry Facility and NEAT ORU, University of California at Davis, One Shields Avenue, Davis, CA 95616-877 (United States)]. E-mail: anavrotsky@ucdavis.edu; Tailhades, Philippe [Centre InterUniversitaire de Recherche et d'Ingenierie des Materiaux (CIRIMAT/LCMIE), Universite Paul Sabatier, Ba-hat timent 2R1, 118, route de Narbonne, 31062 Toulouse, Cedex 04 (France); Coradin, Herve [Centre InterUniversitaire de Recherche et d'Ingenierie des Materiaux (CIRIMAT/LCMIE), Universite Paul Sabatier, Ba-hat timent 2R1, 118, route de Narbonne, 31062 Toulouse, Cedex 04 (France); Wang Miaojun [Thermochemistry Facility and NEAT ORU, University of California at Davis, One Shields Avenue, Davis, CA 95616-877 (United States)

2005-01-15

310

Rates of manganese oxidation in aqueous systems  

USGS Publications Warehouse

The rate of crystal growth of Mn3O4 (hausmannite) and ??MnOOH (feitknechtite) in aerated aqueous manganous perchlorate systems, near 0.01 M in total manganese, was determined at pH levels ranging from 7.00 to 9.00 and at temperatures from 0.5 to 37.4??C. The process is autocatalytic, but becomes psuedo first-order in dissolved Mn2+ activity when the amount of precipitate surface is large compared to the amount of unreacted manganese. Reaction rates determined by titrations using an automated pH-stat were fitted to an equation for precipitate growth. The rates are proportional to surface area of oxide and degree of supersaturation with respect to Mn2+. The oxide obtained at the higher temperature was Mn3O4, but at 0.5?? C only ??MnOOH was formed. At intermediate temperatures, mixtures of these solids were formed. The rate of precipitation of hausmannite is strongly influenced by temperature, and that of feitknechtite much less so. The difference in activation energy may be related to differences in crystal structure of the oxides and the geometry of polymeric hydroxy ion precursors. ?? 1981.

Hem, J.D.

1981-01-01

311

Thermal chemistry of Mn{sub 2}(CO){sub 10} during deposition of thin manganese films on silicon oxide and on copper surfaces  

SciTech Connect

The surface chemistry of dimanganese decacarbonyl on the native oxide of Si(100) wafers was characterized with the aid of x-ray photoelectron spectroscopy. Initial experiments in a small stainless-steel reactor identified a narrow range of temperatures, between approximately 445 and 465 K, in which the deposition of manganese could be achieved in a self-limiting fashion, as is desirable for atomic layer deposition. Deposition at higher temperatures leads to multilayer growth, but the extent of this Mn deposition reverses at even higher temperatures (about 625 K), and also ifhydrogen is added to the reaction mixture. Extensive decarbonylation takes place below room temperature, but limited C-O bond dissociation and carbon deposition are still seen after high exposures at 625 K. The films deposited at low ({approx}450 K) temperatures are mostly in the form of MnO, but at 625 K that converts to a manganese silicate, and upon higher doses a manganese silicide forms at the SiO{sub 2}/Si(100) interface as well. No metallic manganese could be deposited with this precursor on either silicon dioxide or copper surfaces.

Qin Xiangdong; Sun Huaxing; Zaera, Francisco [Department of Chemistry, University of California, Riverside, California 92521 (United States)

2012-01-15

312

Clean cast steel technology. Final report  

SciTech Connect

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.

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

1998-06-01

313

Environment-Assisted Cracking of Twinning Induced Plasticity (TWIP) Steel: Role of pH and Twinning  

NASA Astrophysics Data System (ADS)

This article presents the study of the environment-assisted cracking (EAC) of twinning induced plasticity (TWIP) steels that possess remarkable combination of strength and ductility. EAC of a high-manganese TWIP steel was investigated, using aqueous solutions of different pH, which provided a mechanistic insight into the combined role of the localized deformation due to twinning and the electrochemical characteristic of the steel. Slow strain rate testing in inert environment as well as in acidic, neutral and alkaline solutions, and the fractography of the failed specimens have suggested a profound role of twinning in EAC crack propagation.

Singh Raman, R. K.; Khalissi, Muhammed; Khoddam, Shahin

2014-04-01

314

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated 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 viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This annual topical report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

Hepworth, M.T.; Ben-Slimane, R.

1994-12-01

315

Effects of manganese forms on biogenic amines in the brain and behavioral alterations in the mouse: Long-term oral administration of several manganese compounds  

SciTech Connect

This work has identified the relative toxicity of four forms of manganese, using biogenic amine levels, tissue retention, weight gain, and activity scores as criteria. Male mice were chronically treated with four forms of manganese administered orally, mixed with the diet, for 12 months. The Mn levels were higher in some parts of brain after feeding insoluble salts than after the soluble salts. The concentration of manganese was significantly increased in the liver and spleen of the manganese carbonate-exposed group, compared with the concentration in the control group. Manganese dioxide feeding lowered dopamine and increased homovanilic acid. Since manganese dioxide is a powerful oxidizing agent in organic chemistry, it possibly enhanced the oxidative metabolite of dopamine. Accumulation of manganese in the brain correlated with reduced hypothalamic dopamine levels in the manganese acetate-exposed group; and the amount of manganese accumulated correlated with the intensity of suppression of motor activity. These findings indicate that manganese dioxide is more toxic than divalent manganese. Of the divalent manganese compounds, manganese acetate seemed to have the greatest toxic effect.

Komura, Junko; Sakamoto, Michiko (Hokuriku Univ., Kanazawa (Japan))

1992-02-01

316

Supertough Stainless Bearing Steel  

NASA Technical Reports Server (NTRS)

Composition and processing of supertough stainless bearing steel designed with help of computer-aided thermodynamic modeling. Fracture toughness and hardness of steel exceeds those of other bearing steels like 440C stainless bearing steel. Developed for service in fuel and oxidizer turbopumps on Space Shuttle main engine. Because of strength and toughness, also proves useful in other applications like gears and surgical knives.

Olson, Gregory B.

1995-01-01

317

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

PubMed Central

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

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

2014-01-01

318

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

NASA Technical Reports Server (NTRS)

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.

Richardson, Laurie L.; Nealson, Kenneth H.

1989-01-01

319

Manganese: brain transport and emerging research needs.  

PubMed Central

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

Aschner, M

2000-01-01

320

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

PubMed

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

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

1999-01-01

321

Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore  

USGS Publications Warehouse

Unlike other marine-sedimentary manganese ore deposits, which are largely composed of manganese oxides, the primary ore at Molango (Hidalgo State, Mexico) is exclusively manganese carbonate (rhodochrosite, Mn-calcite, kutnahorite). Stable isotope studies of the carbonates from Molango provide critical new information relevant to the controversy over syngenetic and diagenetic models of stratiform manganese deposit formation. Negative ??13C values for carbonates from mineralized zones at Molango are strongly correlated with manganese content both on a whole rock scale and by mineral species. Whole rock ??13C data fall into three groups: high-grade ore = -16.4 to -11.5%.; manganese-rich, sub-ore-grade = -5.2 to 0%.; and unmineralized carbonates = 0 to +2.5%. (PDB). ??18O data show considerable overlap in values among the three groups: +4.8 to -2.8, -5.4 to -0.3%., and -7.4 to +6.2 (PDB), respectively. Isotopic data for individual co-existing minerals suggest a similar separation of ??13C values: ??13C values from calcite range from -1.1 to +0.7%. (PDB), whereas values from rhodochrosite are very negative, -12.9 to -5.5%., and values from kutnahorite or Mn-calcite are intermediate between calcite and rhodochrosite. 13C data are interpreted to indicate that calcite (i.e. unmineralized carbonate) formed from a normal marine carbon reservoir. However, 13C data for the manganese-bearing carbonates suggest a mixed seawater and organic source of carbon. The presence of only trace amounts of pyrite suggests sulfate reduction may have played a minor part in oxidizing organic matter. It is possible that manganese reduction was the predominant reaction that oxidized organic matter and that it released organic-derived CO2 to produce negative ??13C values and manganese carbonate mineralization. ?? 1988.

Okita, P.M.; Maynard, J.B.; Spiker, E. C.; Force, E.R.

1988-01-01

322

Radiation resistant austenitic stainless steel alloys  

DOEpatents

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.

Maziasz, Philip J. (Oak Ridge, TN); Braski, David N. (Oak Ridge, TN); Rowcliffe, Arthur F. (Oak Ridge, TN)

1989-01-01

323

Effect of lead on the machinability of free-cutting steel  

Microsoft Academic Search

Free-cutting steel AS14 containing lead (0.1-0.17% C, 1.0-1.3% Mn, 0.1-0.25% Si, 0.15% S, 0.1% P, 0.15-0.3% Pb), with high machinability, is widely used in industry. Sulfur forms manganese sulfide, which at a certain size of the inclusions facilitates shearing and easy detachment of shavings. Phosphorus, dissolving in ferrite, reduces the internal friction and creates a stable leading crack. Data concerning

M. A. Krishtal; A. A. Borgardt; Yu. D. Yashin

1977-01-01

324

Studies on Indian Ocean Manganese Nodules  

PubMed

A series of strontium-lanthanum oxide mixed manganese nodules were prepared and characterized by X-ray diffraction, nitrogen adsorption-desorption, electrical conductivity, and surface excess oxygen. X-ray diffraction patterns confirm the formation of perovskite-type oxides at low strontium content (x

Parida; Sahoo; Das

1997-03-15

325

Role of astrocytes in manganese mediated neurotoxicity  

PubMed Central

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

2013-01-01

326

Manganese Neurotoxicity: a Focus on Glutamate Transporters  

PubMed Central

Manganese (Mn) is an essential element that is required in trace amount for normal growth, development as well maintenance of proper function and regulation of numerous cellular and biochemical reactions. Yet, excessive Mn brain accumulation upon chronic exposure to occupational or environmental sources of this metal may lead to a neurodegenerative disorder known as manganism, which shares similar symptoms with idiopathic Parkinson’s disease (PD). In recent years, Mn exposure has gained public health interest for two primary reasons: continuous increased usage of Mn in various industries, and experimental findings on its toxicity, linking it to a number of neurological disorders. Since the first report on manganism nearly two centuries ago, there have been substantial advances in the understanding of mechanisms associated with Mn-induced neurotoxicity. This review will briefly highlight various aspects of Mn neurotoxicity with a focus on the role of astrocytic glutamate transporters in triggering its pathophysiology. PMID:24472696

2013-01-01

327

Analysis for blood manganese used to assess environmental exposure  

SciTech Connect

In this graphite-furnace atomic-absorption spectrometric method for measuring manganese in whole blood, we use a pyrolytic platform to minimize interference by sample matrix. For optimal sample ashing we denature the sample within the furnace with nitric acid and use oxygen as the purge gas at low temperatures. The mean manganese concentration found in blood from 15 unexposed city dwellers was 215 (2 SD 135) nmol/L. By comparison, the range of manganese concentrations in blood sampled from a group of Australian aborigines living near a surface manganese ore deposit on Groote Eylandt, Northern Territory, was much higher (median 405 nmol/L, range 175 to 990 nmol/L).

Hams, G.A.; Fabri, J.K.

1988-06-01

328

Nutritional immunity beyond iron: a role for manganese and zinc  

PubMed Central

Summary Vertebrates sequester iron from invading pathogens, and conversely, pathogens express a variety of factors to steal iron from the host. Recent work has demonstrated that in addition to iron, vertebrates sequester zinc and manganese both intracellularly and extracellularly to protect against infection. Intracellularly, vertebrates utilize the ZIP/ZnT families of transporters to manipulate zinc levels, as well as Nramp1 to manipulate manganese levels, respectively. Extracellularly, the S100 protein calprotectin sequesters manganese and potentially zinc to inhibit microbial growth. To circumvent these defenses, bacteria possess high affinity transporters to import specific nutrient metals. Limiting the availability of zinc and manganese as a mechanism to defend against infection expands the spectrum of nutritional immunity and further establishes metal sequestration as a key defense against microbial invaders. PMID:20015678

Kehl-Fie, Thomas E.; Skaar, Eric P.

2009-01-01

329

MANGANESE--2000 50.1 By Thomas S. Jones  

E-print Network

aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature of manganese by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking

Torgersen, Christian

330

MANGANESE--2001 49.1 By Lisa A. Corathers  

E-print Network

aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature of manganese of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking

Torgersen, Christian

331

MANGANESE--1998 49.1 By Thomas S. Jones  

E-print Network

aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature of manganese of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking

Torgersen, Christian

332

MANGANESE--1999 49.1 By Thomas S. Jones  

E-print Network

aluminum alloys and is used in oxide form in dry cell batteries. The overall level and nature of manganese by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking

Torgersen, Christian

333

Production of steel 32KhG2SAF for drill pipe  

SciTech Connect

The Azerbaidzhan Pipe Plant worked with the Ukrainian Academy of Sciences to produce high-strength chromium-vanadium-manganese steel strengthened by nitriding. The steel is made in open-hearth furnaces by the pig-and-scrap process. Cast nitrided ferrochromium is introduced in the metal bath after preliminary deoxidation and is almost completely assimilated. Ferrovanadium is added to the ladle simultaneously with the deoxidizers. The metal subjected to vanadium-nitride strengthening was weldable and was characterized by a good combination of strength and ductility. Dependence of impact toughness, crack nucleation, and crack growth on temperature was also evaluated.

Babaskin, Yu.A.; Kutishchev, S.M.; Kirchu, I.F.; Dubenko, L.V.; Aliev, I.P.; Podzharskii, B.I.; Isaev, Yu.G.; Laptev, V.K.; Aliev, G.M.

1987-11-01

334

Recovery of zinc and manganese from spent batteries  

NASA Astrophysics Data System (ADS)

The necessity of recycling spent batteries in order to recover metals and to protect the environment is emphasized. Some experiments have been made to develop a hydrometallurgical process for metal recovery in alkaline manganese batteries. The components are easily separated: zinc can be electroplated and manganese(II) can be oxidized to dioxide; Mn(IV) is solubilized in acidic hydrogen peroxide and reprecipitated by bases.

Bartolozzi, Mauro; Braccini, Gaetano; Marconi, Filippo; Bonvini, Stefania

1994-03-01

335

Aerosol Spray Pyrolysis Synthesis of Magnetic Manganese Ferrite Particles  

Microsoft Academic Search

We describe the aerosol spray pyrolysis synthesis and subsequent properties of manganese ferrite (MnFe2O4) submicrometer particles. Various combinations of the chlorides and nitrates of manganese and iron dissolved in water were used as precursors. Typical aerosol reactor residence times were 0.5–1.5s. With insufficient reactor temperature, e.g., 650°C, porous, hollow particles with a mixture of the ferrite and the individual metal

Qiang Li; C. M. Sorensen; K. J. Klabunde; G. C. Hadjipanayis

1993-01-01

336

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

PubMed Central

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 oxygen 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 Rf 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. Images PMID:6746577

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

1984-01-01

337

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

SciTech Connect

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.

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

338

Manganese triacetate as an efficient catalyst for bisperoxidation of styrenes.  

PubMed

A method was developed for the bisperoxidation of styrenes with tert-butyl hydroperoxide in the presence of a catalytic amount of manganese(iii) acetate. It was shown that compounds of manganese in oxidation states 2, 4, and 7 also catalyze this reaction. The target [1,2-bis(tert-butylperoxy)ethyl]arenes were synthesized in yields from 46 to 75%. PMID:25469680

Terent'ev, Alexander O; Sharipov, Mikhail Yu; Krylov, Igor B; Gaidarenko, Darya V; Nikishin, Gennady I

2015-01-21

339

Manganese and limestone interactions during mine water treatment.  

PubMed

Manganese removal from mining-affected waters is an important challenge for the mining industry. Addressed herein is this issue in both batch and continuous conditions. Batch experiments were carried out with synthetic solutions, at 23+/-2 degrees C, initial pH 5.5 and 8.3 g limestone/L. Similarly, continuous tests were performed with a 16.5 mg/L Mn(2+) mine water, at 23 degrees C, initial pH 8.0 and 20.8 g limestone/L. Calcite limestone gave the best results and its fine grinding proved to the most effective parameter for manganese removal. In either synthetic solutions or industrial effluents, the final manganese concentration was below 1 mg/L. A change in limestone surface zeta potential is observed after manganese removal and manganese carbonate formation was suggested by IR spectroscopy. The conclusion is that limestone can remove manganese from industrial effluents for values that comply with environmental regulations. PMID:20570440

Silva, A M; Cruz, F L S; Lima, R M F; Teixeira, M C; Leão, V A

2010-09-15

340

Low Copper and High Manganese Levels in Prion Protein Plaques  

PubMed Central

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

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

341

Low copper and high manganese levels in prion protein plaques  

USGS Publications Warehouse

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.

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

2013-01-01

342

Ultrahigh carbon steels, Damascus steels, and superplasticity  

SciTech Connect

The processing properties of ultrahigh carbon steels (UHCSs) have been studied at Stanford University over the past twenty years. These studies have shown that such steels (1 to 2.1% C) can be made superplastic at elevated temperature and can have remarkable mechanical properties at room temperature. It was the investigation of these UHCSs that eventually brought us to study the myths, magic, and metallurgy of ancient Damascus steels, which in fact, were also ultrahigh carbon steels. These steels were made in India as castings, known as wootz, possibly as far back as the time of Alexander the Great. The best swords are believed to have been forged in Persia from Indian wootz. This paper centers on recent work on superplastic UHCSs and on their relation to Damascus steels. 32 refs., 6 figs.

Sherby, O.D. [Stanford Univ., CA (United States). Dept. of Materials Science and Engineering; Wadsworth, J. [Lawrence Livermore National Lab., CA (United States)

1997-04-01

343

[Evaluation of exposure to fumes arising during welding of non-alloyed and low-alloyed steel by various methods].  

PubMed

Evaluated in the paper is welders' exposure to fumes resulting from welding of nonalloyed and low-alloyed steel, whether pure or coated with protective layers, using two most popular welding techniques for those types of steel, i.e. metal active gas welding (MAG) and manual welding with covered electrode (MMA). Due to different chemical composition of fumes at particular workstations, the proper hygienic evaluation was based on measurements of individual concentrations of fumes in workers' breathing zone. A considerable contribution of the combined exposure was yielded by such fume constituents as manganese, ferrum and zinc (welding of steel coated with zinc protective layers), also chromium (welding of low- and -highalloyed steel), as well as copper (metal gas welding). The highest combined exposure (10-fold allowable value) was that of welders of steel coated with the zinc layer, using the metal active gas welding. PMID:3237059

Matczak, W; Chmielnicka, J

1988-01-01

344

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

SciTech Connect

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).

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

1980-11-01

345

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

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

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

2002-09-01

346

Dzyaloshinskii-Moriya interactions and non-magnetic impurities in the s=1/2 kagome antiferromagnet  

NASA Astrophysics Data System (ADS)

Motivated by recent NMR experiments[1] on ZnCu3(OH)6Cl2, we present an exact diagonalization study of the combined effect of non-magnetic impurities and Dzyaloshinskii-Moriya (DM) interactions in the s=1/2 Kagom'e antiferromagnet. The magnetization response and the correlation matrix data reveal that the dimer freezing which occurs around the vacancy for D=0 [2,3] (D is the magnitude of the DM vectors) persists up to D/J ˜0.07, above which a phase transition to the Q=0 semiclassical 120^o state[4] takes place. Surprisingly however, the dimers next to the vacancy remain strong up to D/J ˜2-3, i.e. well above the critical point. Implications for ZnCu3(OH)6Cl2 will be discussed. 1. A. Olariu, et al., Phys. Rev. Lett. 100, 087202 (2008). 2. S. Dommange, et al., Phys. Rev. B 68, 224416 (2003). 3. A. L"auchli, et al., Phys. Rev. B 76, 144113 (2007). 4. O. C'epas, et al., Phys. Rev. B 78, 140405 (2008).

Rousochatzakis, Ioannis; Manmana, Salvatore; Laeuchli, Andreas; Normand, Bruce; Mila, Frederic

2009-03-01

347

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

SciTech Connect

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.

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

348

Marine prosthecate bacteria involved in the ennoblement of stainless steel.  

PubMed

Ennoblement, a phenomenon in which open-circuit potential is elevated to a noble value, triggers metal corrosion in the environment and is considered to be biologically catalysed. This study investigated the involvement of marine microorganisms in the ennoblement of stainless steel coupons in sea water pumped from Kamaishi Bay. Scanning electron microscopy (SEM) showed significant attachment of prosthecate bacteria on the surfaces of stainless steel coupons in the course of ennoblement. In denaturing gradient gel electrophoresis (DGGE) analyses of polymerase chain reaction-amplified bacterial 16S rDNA fragments, several major bands were detected from the surface of the ennobled coupons, including those affiliated with the alpha and gamma subclasses of the Proteobacteria. After these observations, bacterial strains were isolated from the surface of the ennobled coupon. The 16S rDNA analysis revealed that a bacterial isolate (designated PWB3) corresponded to a major DGGE band representing an alpha-Proteobacterial population; a database analysis showed that its closest relative was Rhodobium spp., albeit with low homology ( approximately 89%). SEM indicated that this bacterium was a prosthecate bacterium that was morphologically similar to those observed on the ennobled coupons. In pure culture of strain PWB3, stainless steel coupons were ennobled when the culture was supplemented with MnCl2. Manganese was recovered from the surface of the ennobled coupons after treatment with a reducing agent. These results suggest that the attachment of manganese-oxidizing prosthecate bacteria triggered the ennoblement of stainless steel in Kamaishi Bay sea water. PMID:14510846

Baker, Paul W; Ito, Kimio; Watanabe, Kazuya

2003-10-01

349

Structural and spectroscopic comparison of manganese-containing superoxide dismutases.  

PubMed

Predicted secondary structures and optical properties of four manganese-containing superoxide dismutases isolated from Saccharomyces cerevisiae, Bacillus stearothermophilus, Escherichia coli and human liver are compared. The structural predictions are further compared with the known crystal structure of the manganese-containing superoxide dismutase from Thermus thermophilus HB8. The secondary structures of the four dismutases are predicted by the methods of Chou and Fasman (Adv. Enzymol. 47 (1978) 45-148), Garnier et al. (J. Mol. Biol. 120 (1978) 97-120) and Lim (J. Mol. Biol. 88 (1974) 873-894). The three models show satisfactory agreement and predict that the enzymes have a mixed alpha-helix and beta-sheet structure, and that they have homologous structures. The former conclusion is also reached from an analysis of the hydrophobic character of the amino-acid sequences of the four proteins according to Kyte and Doolittle (J. Mol. Biol. 157 (1982) 105-132). The calculation of the secondary structure based on the 185-260 nm circular dichroism spectrum of manganese-containing superoxide dismutase from S. cerevisiae reveals that the enzyme consists of 61% alpha-helix, 13% beta-sheet, 11% turn and 8% random coil conformations, which is in good accordance with the prediction based on the amino-acid sequences. Comparison of the 400-700 nm circular dichroism spectra of manganese-containing superoxide dismutase from S. cerevisiae, E. coli and T. thermophilus demonstrates that manganese atoms have homologous coordination in the three enzymes. This investigation based on primary structures and spectral properties indicates that the four dismutases have the same overall structure. Since the structural predictions are in good agreement with the structure found for the manganese-containing superoxide dismutase from T. thermophilus HB8, it can be concluded that this structure is representative for the four enzymes and probably for manganese-containing superoxide dismutases in general. PMID:3307925

Bjerrum, M J

1987-09-24

350

Stress Corrosion Cracking Behavior of Cast Stainless Steels  

SciTech Connect

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.

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

2009-01-01

351

Welding Rustproof Steels  

NASA Technical Reports Server (NTRS)

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.

Hoffmann, W

1929-01-01

352

Comminuting irradiated ferritic steel  

DOEpatents

Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

Bauer, Roger E. (Kennewick, WA); Straalsund, Jerry L. (Kennewick, WA); Chin, Bryan A. (Auburn, AL)

1985-01-01

353

Manganese Superoxide Dismutase: Guardian of the Powerhouse  

PubMed Central

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

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

2011-01-01

354

Xenon in Mercury-Manganese Stars  

E-print Network

Previous studies of elemental abundances in Mercury-Manganese (HgMn) stars have occasionally reported the presence of lines of the ionized rare noble gas Xe II, especially in a few of the hottest stars with Teff ~ 13000--15000 K. A new study of this element has been undertaken using observations from Lick Observatory's Hamilton Echelle Spectrograph. In this work, the spectrum synthesis program UCLSYN has been used to undertake abundance analysis assuming LTE. We find that in the Smith & Dworetsky sample of HgMn stars, Xe is vastly over-abundant in 21 of 22 HgMn stars studied, by factors of 3.1--4.8 dex. There does not appear to be a significant correlation of Xe abundance with Teff. A comparison sample of normal late B stars shows no sign of Xe II lines that could be detected, consistent with the expected weakness of lines at normal abundance. The main reason for the previous lack of widespread detection in HgMn stars is probably due to the strongest lines being at longer wavelengths than the photographic blue. The lines used in this work were 4603.03A, 4844.33A and 5292.22A.

M. M. Dworetsky; J. L. Persaud; K. Patel

2008-01-16

355

Redundancy among manganese peroxidases in Pleurotus ostreatus.  

PubMed

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

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

2013-04-01

356

Electrical behavior of natural manganese dioxide (NMD)  

SciTech Connect

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.

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

357

Genetic factors and manganese-induced neurotoxicity  

PubMed Central

Manganese (Mn), is a trace metal required for normal physiological processes in humans. Mn levels are tightly regulated, as high levels of Mn result in accumulation in the brain and cause a neurological disease known as manganism. Manganism shares many similarities with Parkinson’s disease (PD), both at the physiological level and the cellular level. Exposure to high Mn-containing environments increases the risk of developing manganism. Mn is absorbed primarily through the intestine and then released in the blood. Excessive Mn is secreted in the bile and excreted in feces. Mn enters and exits cells through a number of non-specific importers localized on the cell membrane. Mutations in one of the Mn exporters, SLC30A10 (solute carrier family 30, member 10), result in Mn induced toxicity with liver impairments and neurological dysfunction. Four PD genes have been identified in connection to regulation of Mn toxicity, shedding new light on potential links between manganism and PD. PMID:25136353

Chen, Pan; Parmalee, Nancy; Aschner, Michael

2014-01-01

358

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

E-print Network

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

Sparks, Donald L.

359

Steel slag in acid mine drainage treatment and control  

SciTech Connect

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.

Ziemkiewicz, P.; Skousen, J.

1999-07-01

360

Manganese and acute paranoid psychosis: a case report  

PubMed Central

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

2011-01-01

361

Local Structure Analysis of Strontium Sorption to Hydrous Manganese Oxide.  

PubMed

To develop mechanistic models of contaminant distribution processes, we conducted an X-ray absorption fine structure analysis of strontium sorption to hydrous manganese oxide (HMO). Sr K-edge measurements were performed at 298, 220, and 77 K, and at sample loadings from 10(-4) to 10(-2) mol Sr/g HMO. Results from fitting the first shell in the sorbed samples indicate that strontium is surrounded by 10-12 oxygen atoms at an average distance of 2.58 Å. This coordination environment is consistent with the strontium atom remaining hydrated upon sorption to the oxide, where in water hydrated strontium has approximately 9 atoms of oxygen at 2.62 Å. Furthermore, the temperature dependence of the strontium-oxygen bond also suggests physical adsorption due to the large contribution of the dynamic component of the Debye Waller factor. Although second-shell data are consistent with either 3 manganese atoms at 4.12 Å or 6 strontium atoms at 3.88 Å, both the near-edge and fine structure data for the manganese K-edge indicate that the local coordination environment of the manganese ion remains intact as a function of time or strontium sorption. Furthermore, the local structure of amorphous manganese oxide is highly ordered. Copyright 2000 Academic Press. PMID:10727353

Axe; Tyson; Trivedi; Morrison

2000-04-15

362

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2013-07-01

363

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

...2014-07-01 2014-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2014-07-01

364

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2012-07-01

365

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2011-07-01

366

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...

2010-07-01

367

The effect of phosphate application on manganese content of plants grown on neutral and alkaline soils  

Microsoft Academic Search

Summary In four field experiments high rates of granular triple superphosphate and repeated sprays of manganese sulphate were applied to oats and sugar beet on land known to produce manganese-deficiency symptoms in these crops. It was found that spraying did not increase the manganese content of the foliage while application of superphosphate did.

Sigurd Larsen

1964-01-01

368

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

369

Proceedings of the symposium on manganese dioxide electrode theory and practice for electrochemical applications  

Microsoft Academic Search

This book presents the papers given at a symposium on the use of manganese dioxide in the fabrication of electric batteries. Topics considered at the symposium included manganese oxides as battery cathodes, electrochemistry, chemical activation, chemical reaction kinetics, voltage recovery behavior, rechargeability, and manganese dioxide in alkaline electrolytes.

R. L. Middaugh; J. C. Hunter; B. Schumm; M. P. Grotheer

1985-01-01

370

40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Manganese yttrium oxide (Mn2YO5). 721.10013 Section 721...Substances § 721.10013 Manganese yttrium oxide (Mn2YO5). (a) Chemical substance...substance identified as manganese yttrium oxide (Mn2 YO5 ) (PMN...

2011-07-01

371

40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).  

...2014-07-01 false Manganese yttrium oxide (Mn2YO5). 721.10013 Section 721...Substances § 721.10013 Manganese yttrium oxide (Mn2 YO5 ). (a) Chemical substance...substance identified as manganese yttrium oxide (Mn2 YO5 ) (PMN...

2014-07-01

372

40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).  

...2014-07-01 false Manganese yttrium oxide (MnYO3). 721.10009 Section 721...Substances § 721.10009 Manganese yttrium oxide (MnYO3 ). (a) Chemical substance...substance identified as manganese yttrium oxide (MnYO3 ) (PMN P-00-1122;...

2014-07-01

373

40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Manganese yttrium oxide (MnYO3). 721.10009 Section 721...Substances § 721.10009 Manganese yttrium oxide (MnYO3 ). (a) Chemical substance...substance identified as manganese yttrium oxide (MnYO3 ) (PMN P-00-1122;...

2012-07-01

374

40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Manganese strontium oxide (MnSrO3). 721.10008 Section 721...Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance...substance identified as manganese strontium oxide (MnSrO3 ) (PMN P-00-1121;...

2011-07-01

375

Joining of highly aluminum-doped lanthanum strontium manganese oxide with tetragonal zirconia by plastic deformation  

E-print Network

Joining of highly aluminum-doped lanthanum strontium manganese oxide with tetragonal zirconia February 2008; accepted 24 March 2008 Abstract Aluminum-doped lanthanum strontium manganese oxide, La0.77Sr at the interface. © 2008 Elsevier B.V. All rights reserved. Keywords: Lanthanum strontium aluminum manganese oxide

Dutta, Prabir K.

376

40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Lithium manganese oxide (LiMn204) (generic...Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic...chemical substance identified generically as lithium manganese oxide (LiMn204)...

2013-07-01

377

40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Lithium manganese oxide (LiMn204) (generic...Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic...chemical substance identified generically as lithium manganese oxide (LiMn204)...

2011-07-01

378

40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).  

...2014-07-01 2014-07-01 false Lithium manganese oxide (LiMn204) (generic...Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic...chemical substance identified generically as lithium manganese oxide (LiMn204)...

2014-07-01

379

40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Lithium manganese oxide (LiMn204) (generic...Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic...chemical substance identified generically as lithium manganese oxide (LiMn204)...

2012-07-01

380

Utilisation of solid waste products for manganese removal from mine waters  

Microsoft Academic Search

Manganese is a common contaminant of mine waters and other waste waters, and is notoriously difficult to remove due to its high solubility over a wide range of pH. Previously, systems designed to remove manganese from mine waters used high pH substrates such as limestone to promote the chemical oxidation of manganese oxyhydroxides, which then act as a catalyst for

Bamforth Selina M; Manning David; Ian Singleton; Karen L. Johnson

381

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...Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a...The chemical substance identified as manganese strontium oxide (MnSrO3 )...

2010-07-01

382

40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Manganese yttrium oxide (MnYO3). 721.10009...Chemical Substances § 721.10009 Manganese yttrium oxide (MnYO3). (a) Chemical...The chemical substance identified as manganese yttrium oxide (MnYO3 ) (PMN...

2010-07-01

383

40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Lithium manganese oxide (LiMn204) (generic name...Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name...substance identified generically as lithium manganese oxide (LiMn204)...

2010-07-01

384

40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Manganese yttrium oxide (Mn2YO5). 721.10013...Chemical Substances § 721.10013 Manganese yttrium oxide (Mn2YO5). (a...The chemical substance identified as manganese yttrium oxide (Mn2 YO5 )...

2010-07-01

385

76 FR 47996 - Cobalt Lithium Manganese Nickel Oxide; Significant New Use Rule  

Federal Register 2010, 2011, 2012, 2013

...EPA-HQ-OPPT-2009-0922; FRL-8878-2] RIN 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Significant...for the chemical substance identified as cobalt lithium manganese nickel oxide (CAS No...for the chemical substance identified as cobalt lithium manganese nickel oxide...

2011-08-08

386

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

Federal Register 2010, 2011, 2012, 2013

...EPA-HQ-OPPT-2009-0922; FRL-8853-2] RIN 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Withdrawal...for the chemical substance identified as cobalt lithium manganese nickel oxide (CAS No...EPA is withdrawing the rule issued for cobalt lithium manganese nickel oxide (PMN...

2010-11-18

387

Methods of forming steel  

DOEpatents

In one aspect, the invention encompasses a method of forming a steel. A metallic glass is formed and at least a portion of the glass is converted to a crystalline steel material having a nanocrystalline scale grain size. In another aspect, the invention encompasses another method of forming a steel. A molten alloy is formed and cooled the alloy at a rate which forms a metallic glass. The metallic glass is devitrified to convert the glass to a crystalline steel material having a nanocrystalline scale grain size. In yet another aspect, the invention encompasses another method of forming a steel. A first metallic glass steel substrate is provided, and a molten alloy is formed over the first metallic glass steel substrate to heat and devitrify at least some of the underlying metallic glass of the substrate.

Branagan, Daniel J. (Iona, ID); Burch, Joseph V. (Shelley, ID)

2001-01-01

388

Effect of Internal Hydrogen on Delayed Cracking of Metastable Low-Nickel Austenitic Stainless Steels  

NASA Astrophysics Data System (ADS)

Metastable austenitic stainless steels, especially manganese-alloyed low-nickel grades, may be susceptible to delayed cracking after forming processes. Even a few wppm of hydrogen present in austenitic stainless steels as an inevitable impurity is sufficient to cause cracking if high enough fraction of strain-induced ?'-martensite and high residual tensile stresses are present. The role of internal hydrogen content in delayed cracking of several metastable austenitic stainless steels having different alloying chemistries was investigated by means of Swift cup tests, both in as-supplied state and after annealing at 673 K (400 °C). Hydrogen content of the test materials in each state was analyzed with three different methods: inert gas fusion, thermal analysis, and thermal desorption spectroscopy. Internal hydrogen content in as-supplied state was higher in the studied manganese-alloyed low-nickel grades, which contributed to susceptibility of unstable grades to delayed cracking. Annealing of the stainless steels reduced their hydrogen content by 1 to 3 wppm and markedly lowered the risk of delayed cracking. Limiting drawing ratio was improved from 1.4 to 1.7 in grade 204Cu, from 1.7 to 2.0 in grade 201 and from 1.8 to 2.12 in grade 301. The threshold levels of ?'-martensite and residual stress for delayed cracking at different hydrogen contents were defined for the test materials.

Papula, Suvi; Talonen, Juho; Todoshchenko, Olga; Hänninen, Hannu

2014-10-01

389

Manganese-oxidizing bacteria mediate the degradation of 17?-ethinylestradiol.  

PubMed

Manganese (II) and manganese-oxidizing bacteria were used as an efficient biological system for the degradation of the xenoestrogen 17?-ethinylestradiol (EE2) at trace concentrations. Mn(2+)-derived higher oxidation states of Mn (Mn(3+), Mn(4+)) by Mn(2+)-oxidizing bacteria mediate the oxidative cleavage of the polycyclic target compound EE2. The presence of manganese (II) was found to be essential for the degradation of EE2 by Leptothrix discophora, Pseudomonas putida MB1, P. putida MB6 and P. putida MB29. Mn(2+)-dependent degradation of EE2 was found to be a slow process, which requires multi-fold excess of Mn(2+) and occurs in the late stationary phase of growth, implying a chemical process taking place. EE2-derived degradation products were shown to no longer exhibit undesirable estrogenic activity. PMID:21261871

Sabirova, Julia S; Cloetens, L F F; Vanhaecke, L; Forrez, I; Verstraete, Willy; Boon, N

2008-11-01

390

Manganese-enhanced MRI: an exceptional tool in translational neuroimaging.  

PubMed

The metal manganese is a potent magnetic resonance imaging (MRI) contrast agent that is essential in cell biology. Manganese-enhanced magnetic resonance imaging (MEMRI) is providing unique information in an ever-growing number of applications aimed at understanding the anatomy, the integration, and the function of neural circuits both in normal brain physiology as well as in translational models of brain disease. A major drawback to the use of manganese as a contrast agent, however, is its cellular toxicity. Therefore, paramount to the successful application of MEMRI is the ability to deliver Mn2+ to the site of interest using as low a dose as possible while preserving detectability by MRI. In the present work, the different approaches to MEMRI in translational neuroimaging are reviewed and challenges for future identified from a practical standpoint. PMID:18550591

Silva, Afonso C; Bock, Nicholas A

2008-07-01

391

Metallic solvent extraction of manganese and titanium from ferroalloys  

NASA Astrophysics Data System (ADS)

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.

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

1990-04-01

392

Carbothermal Reduction of Manganese Oxide in Different Gas Atmospheres  

NASA Astrophysics Data System (ADS)

Carbothermal reduction of manganese oxides was studied in hydrogen, helium, and argon at different temperatures and carbon-to-manganese oxide ratios. Isothermal and temperature programmed carbothermal reduction experiments were conducted in a fixed bed reactor in a vertical tube furnace, with on-line monitoring of gas composition by the CO-CO2 infrared sensor. The extent of reduction was calculated using the off-gas composition and LECO oxygen contents in the reduced samples. In all gas atmospheres, the reaction rate increased with temperature. The reduction rate of manganese oxide in hydrogen was higher than in helium, and in helium higher than in argon. This was attributed to the involvement of hydrogen in the reduction process and the difference in CO and CO2 diffusion coefficients in helium and argon.

Kononov, Ring; Ostrovski, Oleg; Ganguly, Samir

2008-10-01

393

Manganese superoxide dismutase: beyond life and death  

PubMed Central

Manganese superoxide dismutase (MnSOD) is a nuclear-encoded antioxidant enzyme that localizes to the mitochondria. Expression of MnSOD is essential for the survival of aerobic life. Transgenic mice expressing a luciferase reporter gene under the control of the human MnSOD promoter demonstrate that the level of MnSOD is reduced prior to the formation of cancer. Overexpression of MnSOD in transgenic mice reduces the incidences and multiplicity of papillomas in a DMBA/TPA skin carcinogenesis model. However, MnSOD deficiency does not lead to enhanced tumorigenicity of skin tissue similarly treated because MnSOD can modulate both the p53-mediated apoptosis and AP-1-mediated cell proliferation pathways. Apoptosis is associated with an increase in mitochondrial levels of p53 suggesting a link between MnSOD deficiency and mitochondrial-mediated apoptosis. Activation of p53 is preventable by application of a SOD mimetic (MnTE-2-PyP5+). Thus, p53 translocation to mitochondria and subsequent inactivation of MnSOD explain the observed mitochondrial dysfunction that leads to transcription-dependent mechanisms of p53-induced apoptosis. Administration of MnTE-2-PyP5+ following apoptosis but prior to proliferation leads to suppression of protein carbonyls and reduces the activity of AP-1 and the level of the proliferating cellular nuclear antigen, without reducing the activity of p53 or DNA fragmentation following TPA treatment. Remarkably, the incidence and multiplicity of skin tumors are drastically reduced in mice that receive MnTE-2-PyP5+ prior to cell proliferation. The results demonstrate the role of MnSOD beyond its essential role for survival and suggest a novel strategy for an antioxidant approach to cancer intervention. PMID:20454814

Holley, Aaron K.; Dhar, Sanjit Kumar; Xu, Yong

2010-01-01

394

Recent progress in understanding reactor pressure vessel steel embrittlement  

NASA Astrophysics Data System (ADS)

This paper reviews the current understanding of the basic mechanisms of irradiation embrittlement in reactor pressure vessel steels. Radiation enhanced diffusiona at operating temperatures around 290°C leads to the formation of various ultrafine scale hardening phases, including copper rich and copper catalysed manganese-nickel rich precipitates. Other nanofeatures that do not require copper, so-called matrix defects, include alloy phosphides and carbonitrides as well as defect cluster-solute complexes. Matrix defects that are thermally unstable (anneal) under irradiation play a very important role in mediating flux and temperature effects. The balance of features depends on the composition of the steel and the irradiation conditions. Copper enriched phases, which are the dominant embrittling feature in alloys containing significant trace quantities of this element, are fairly well understood. In contrast, the detailed identity and etiology of the matrix defects and manganese-nickel rich phases that may form in very low copper steels has not yet been established. Embrittlement of typical (Mn-Mo-Ni) pressure vessel steels, manifested as shifts in Charpy V-notch transition temperature, can generally be related to yield stress increases. Yield stress increases from copper rich precipitates are consistent with predictions using defect-obstacle interaction theory coupled with a new model for superposition of the hardening from both pre- and post-irradiation sources of strength. Details of the strengthening contributions from the other irradiation features are not as well established, but appear to be reasonably consistent with theory. These concepts have led to the development of thermodynamic-kinetic-micromechanical models that are broadly consistent with experiment, and rationalize the highly synergistic effects of important irradiation (e.g., temperature, flux, fluence) and metallurgical (e.g., copper, nickel, manganese, phosphorous and heat treatment) variables on both irradiation hardening and hardening recovery during post-irradiation annealing. Open questions can be addressed with a hierarchy of new theoretical and experimental tools, which range from atomistic modeling to tomographic methods of observing the sequence-of-events leading to fracture. Advanced microstructural evolution, microstructure-property and micromechanical models, validated and calibrated by well designed experiments, will greatly enhance our ability to predict pressure vessel embrittlement and to resolve out-standing technical issues.

Odette, G. R.; Lucas, G. E.

395

The sensitized luminescence of manganese-activated calcite  

USGS Publications Warehouse

Synthetic manganese-activated calcites are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural calcites is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural calcites to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".

Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.

1947-01-01

396

Characterization of High-Velocity Solution Precursor Flame-Sprayed Manganese Cobalt Oxide Spinel Coatings for Metallic SOFC Interconnectors  

NASA Astrophysics Data System (ADS)

A modified high-velocity oxy-fuel spray (HVOF) thermal spray torch equipped with liquid feeding hardware was used to spray manganese-cobalt solutions on ferritic stainless steel grade Crofer 22 APU substrates. The HVOF torch was modified in such a way that the solution could be fed axially into the combustion chamber through 250- and 300-?m-diameter liquid injector nozzles. The solution used in this study was prepared by diluting nitrates of manganese and cobalt, i.e., Mn(NO3)2·4H2O and Co(NO3)2·6H2O, respectively, in deionized water. The as-sprayed coatings were characterized by X-ray diffraction and field-emission scanning electron microscopy operating in secondary electron mode. Chemical analyses were performed on an energy dispersive spectrometer. Coatings with remarkable density could be prepared by the novel high-velocity solution precursor flame spray (HVSPFS) process. Due to finely sized droplet formation in the HVSPFS process and the use of as delivered Crofer 22 APU substrate material having very low substrate roughness ( R a < 0.5 ?m), thin and homogeneous coatings, with thicknesses lower than 10 ?m could be prepared. The coatings were found to have a crystalline structure equivalent to MnCo2O4 spinel with addition of Co-oxide phases. Crystallographic structure was restored back to single-phase spinel structure by heat treatment.

Puranen, Jouni; Laakso, Jarmo; Kylmälahti, Mikko; Vuoristo, Petri

2013-06-01

397

Elimination of impurity-induced embrittlement in steel. Part 1: impurity segregation and temper embrittlement  

SciTech Connect

The effects of compositional and microstructural parameters on the temper embrittlement susceptibility of Ni-Cr and Cr-Mo type steels have been investigated. Results show the three principal variables affecting the embrittlement behavior of the steels to be the grainboundary composition, grain size and the hardness. Unified embrittlement equations have been developed relating the combined effect of the three variables to the transtition temperature of the steel. For Cr-Mo type steels not containing any nickel, phosphorous was found to be the major impurity responsible for temper embrittlement. Manganese and silicon were also found to be detrimental due to their interactive effects with phosphorous. The temperature of the transformation product (bainite vs martensite) was not found to significantly influence the embrittlement susceptibility of the Cr-Mo steels. Auger electron spectroscopic analysis of the surface layers of samples of the various steels heated to elevated temperatures has also been completed. Results of this analysis show that this technique can be successfully applied for determining the kinetics of segregation processes in complex steels and to understand the effects of minor alloying elements on the segregation behavior of impurity elements.

McMahon, C.J. Jr.; Takayama, S.; Ogura, T.; Fu, S.C.; Graham, W.R.; Yen, A.C.; DiDio, R.

1980-09-01

398

Iron and manganese are two similar ele-ments that can be a nuisance in a drinking  

E-print Network

Iron and manganese are two similar ele- ments that can be a nuisance in a drinking water supply. Iron is more common than manganese, but they often occur together. They are not hazardous to health. What problems do iron and manganese cause? Iron and manganese can give water an unpleasant taste, odor

399

Effect of phosphorus on the structure and properties of 5Kh20N4AG9 steel  

Microsoft Academic Search

1.Alloying austenitic chromium-manganese-nickel steel 5Kh20N4AG9 with phosphorus in amounts up to 0.2% improves the mechanical properties of the steel at elevated and room temperatures.2.The best combination of mechanical properties is obtained by alloying with 0.2% P and up to 1% Mo.3.The addition of about 0.2% P increases the intensity of precipitation hardening (carbides of the Cr23C6 type and Cr2N nitrides)

K. A. Verner; V. D. Zelenova; V. M. Doronin; A. F. Buinov

1967-01-01

400

History of ultrahigh carbon steels  

Microsoft Academic Search

The history and development of ultrahigh carbon steels (i.e., steels containing between 1 and 2.l percent C and now known as UHCS) are described. The early use of steel compositions containing carbon contents above the eutectoid level is found in ancient weapons from around the world. For example, both Damascus and Japanese sword steels are hypereutectoid steels. Their manufacture and

J. Wadsworth; O. D. Sherby

1997-01-01

401

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

PubMed

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

Zayed, J; Vyskocil, A; Kennedy, G

1999-01-01

402

Effect of extracellular manganese on amylase release from dispersed pancreatic acini.  

PubMed

In dispersed acini from guinea pig pancreas, adding extracellular manganese increased amylase release. A significant effect could be detected with 0.25 mM manganese, and maximal stimulation occurred with 1 mM manganese. When manganese was added, the rate of amylase release did not change during the first 20 min of incubation and then gradually increased to a new steady state by 80 min, which with 1 mM manganese represented a fourfold increase in the rate of enzyme release. Extracellular manganese inhibited the stimulation of amylase release caused by those secretagogues that mobilize cellular calcium but augmented the stimulation caused by those secretagogues whose actions are mediated by cellular cAMP. The mechanism by which manganese altered stimulated amylase secretion differed from the mechanism by which manganese stimulated basal amylase release because the change in stimulated release was maximal within 10 min, whereas the change in basal release did not occur until after 20 min. The actions of manganese on secretagogue-stimulated amylase release were not attributable to manganese-induced changes in secretagogue-stimulated calcium outflux or cAMP and, instead, appear to result from actions of manganese on one of the later steps in the mechanisms for stimulating the secretory process. PMID:6171168

Abdelmoumene, S; Gardner, J D

1981-11-01

403

Effect of Silicon on the Desulfurization of Al-Killed Steels: Part I. Mathematical Model  

NASA Astrophysics Data System (ADS)

Recent observations suggest that increased silicon levels improve ladle desulfurization of aluminum-killed steel. While the overall desulfurization reaction of Al-killed steels does not show a direct role of silicon in desulfurization, model calculations are presented which test the idea that silicon suppresses the reduction of silica which can consume aluminum at the slag/metal interface. Consumption of aluminum would increase the oxygen potential at the slag/metal interface and decrease the sulfur partition coefficient between slag and metal. The model considers the coupled reactions of the reduction of silica, iron oxide, and manganese oxide in the slag and desulfurization of the steel by aluminum. The results show that silicon can indeed suppress consumption of aluminum at the slag/metal interface by side reactions other than desulfurization, with silicon affecting both the kinetics and the equilibrium of desulfurization.

Roy, Debdutta; Pistorius, Petrus Christiaan; Fruehan, Richard J.

2013-10-01

404

Tool steels. 5. edition  

SciTech Connect

The revision of this authoritative work contains a significant amount of new information from the past nearly two decades presented in an entirely new outline, making this a must have reference for engineers involved in tool-steel production, as well as in the selection and use of tool steels in metalworking and other materials manufacturing industries. The chapter on tool-steel manufacturing includes new production processes, such as electroslag refining, vacuum arc remelting, spray deposition processes (Osprey and centrifugal spray), and powder metal processing. The seven chapters covering tool-steel types in the 4th Edition have been expanded to 11 chapters covering nine main groups of tool steels as well as other types of ultrahigh strength steels sometimes used for tooling. Each chapter discusses in detail processing, composition, and applications specific to the particular group. In addition, two chapters have been added covering surface modification and trouble shooting production and performance problems.

Roberts, G.; Krauss, G.; Kennedy, R.

1998-12-31

405

EFFECTS OF MANGANESE AND THEIR MODIFICATION BY HEXAMETAPHOSPHATE  

EPA Science Inventory

The ability of oral Mn(+2) to produce the depletions of dopamine in the corpus striata characteristic of the Parkinson-like syndrome in manganese workers was examined in rats. A second objective of this work was to study the biological interactions between Mn(+2) and sodium hexam...

406

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 ...

407

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...

408

Effects of Succinate on Manganese Toxicity in Pea Plants  

Microsoft Academic Search

Pea (Pisum sativum cv. Citrine) plants were grown in nutrient solution containing various manganese (Mn) concentrations in the presence or absence of succinate to evaluate the potential role of succinate in the plant tolerance to Mn excess. Supplying pea plants with excess Mn led to a reduction in the relative growth rate (RGR), chlorophyll a and b content, photosynthetic O2

Snejana Doncheva; Katya Georgieva; Valya Vassileva; Zlatimira Stoyanova; Nanko Popov; George Ignatov

2005-01-01

409

DIFFERENTIAL RESPONSE OF TWO OLIVE CULTIVARS TO EXCESS MANGANESE  

Microsoft Academic Search

The response of three-month-old rooted cuttings of the olive cultivars ‘Picual’ and ‘Koroneiki’ grown in black plastic bags containing perlite as a substrate to excess manganese (Mn) (640 ?M) was studied. The rooted cuttings were irrigated with 50% modified Hoagland nutrient solution. At the end of the experimental period, which lasted 130 days, the total fresh and dry weights, as

T. Chatzistathis; I. Papadakis; I. Therios; A. Patakas; A. Giannakoula; G. Menexes

2012-01-01

410

Structural Characterization of Biogenic Manganese Oxides Produced in Sea Water  

NASA Astrophysics Data System (ADS)

Manganese oxides have been coined as the "scavengers of the sea" and play important roles in both marine and freshwater systems. Natural manganese oxide nanoparticles and grain coatings are ubiquitous in the environment and profoundly impact the quality of sediments via their ability to degrade and sequester contaminants. These oxides are believed to form dominantly via oxidation of Mn(II) by marine and freshwater bacteria and have extremely high sorptive capacities for heavy metals. We have used XANES, EXAFS, and synchrotron (SR)-XRD techniques to study biogenic manganese oxides produced by spores of the marine Bacillus sp., strain SG-1 in seawater as a function of reaction time under fully in-situ conditions. The primary biogenic solid-phase Mn oxide product is a hexagonal layered phyollomanganate with an oxidation state similar to that in delta-MnO2. XRD data show the biooxides to have a phyllomanganate 10 basal plane spacing, suggesting the interlayer is hydrated and contains calcium. As the experiment continues, the initial biooxide changes to show triclinic symmetry. Fits to these EXAFS spectra suggest the octahedral layers have low Mn octahedral site vacancies in the lattice and the latyers bend to accommodate Jahn-Teller distortions creating the change in symmetry. The oxides observed in this study as models of Mn(II) bio-oxidation may be representative of the most abundant manganese oxide phase suspended in the oxic and sub-oxic zones of the oceanic water column.

Webb, S. M.; Bargar, J. R.; Tebo, B. M.

2003-12-01

411

The Spectrum of the Manganese-Scandium Star phi Herculis  

Microsoft Academic Search

Among manganese stars, varphi Herculis is of great interest because of the unusual strength of the scandium lines. We present intensity measurements for numerous lines of Cii, Mg i, Mg ii, Si ii, Ca ii, Sc ii, Ti ii, Cr ii, Mn i, Mn ii, Fe i, Fe ii, Co ii, Sr ii, Yii, and Zr ii.

Lawrence H. Aller; John E. Ross; R. Erik Zimmermann

1970-01-01

412

The spectrum of the manganese-scandium star ? Herculis  

Microsoft Academic Search

Among manganese stars, ? Herculis is of great interest because of the unusual strength of the scandium lines. We present intensity measurements for numerous lines ofCii, Mgi, Mgii, Siii, Caii, Scii, Tiii, Crii, Mni, Mnii, Fei, Feii, Coii, Srii,Yii, and Zrii.

Lawrence H. Aller; John E. Ross; R. Erik Zimmermann

1970-01-01

413

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...

414

REGULAR ARTICLE Interaction of nickel and manganese in accumulation  

E-print Network

REGULAR ARTICLE Interaction of nickel and manganese in accumulation and localization in leaves as Mn increased. Synchrotron X-ray fluores- cence mapping of whole fresh leaves showed localized than 50 Ni hyperaccumulator species, many of which can achieve 3% dry weight Ni in leaf biomass (Reeves

Sparks, Donald L.

415

Discovery of Chromium, Manganese, Nickel, and Copper Isotopes  

E-print Network

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.

Garofali, K; Thoennessen, M

2010-01-01

416

Biological Indicator of Manganese54 Contamination in Terrestrial Environments  

Microsoft Academic Search

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.

Raffaele Cavalloro; Oscar Ravera

1966-01-01

417

INHALATION TOXICOLOGY OF AIRBORNE PARTICULATE MANGANESE IN RHESUS MONKEYS  

EPA Science Inventory

Four male and four female rhesus monkeys were exposed to manganese oxide (Mn3O4) aerosol at 100 micrograms/cubic meter in an exposure chamber for periods up to 66 weeks. Three male and three female monkeys were maintained as unexposed controls. Observation and clinical chemistry ...

418

Ultrahigh Carbon Steels  

NASA Astrophysics Data System (ADS)

Recent studies and results on ultrahigh carbon (UHC) steels suggest that major development efforts on these steels are timely and that programs to evaluate prototype structural components should be initiated. These recent results include: the development of economical processing techniques incorporating a divorced eutectoid transformation, the improvement of room temperature strength and ductility by heat treatment, the enhancement of superplastic properties through dilute alloying with silicon, and the attainment of exceptional notch impact strength in laminated UHC steel composites manufactured through solid state bonding. The unique mechanical properties achieved in UHC steels are due to the presence of micron-size fer-rite grains and ultrafine spheroidized carbides.

Sherby, O. D.; Oyama, T.; Kum, D. W.; Walser, B.; Wadsworth, J.

1985-06-01

419

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

E-print Network

??Les aciers TWIP (TWinning Induced Plasticity) à haute teneur en manganèse sont particulièrement prometteurs pour les applications automobiles de par leur excellent compromis entre résistance… (more)

Béal, Coline

2011-01-01

420

Influence of carbon, manganese and nickel on microstructure and properties of strong steel  

E-print Network

procedure. Shielded metal arc welding (SMAW), flux cored arc welding, and submerged arc welding offer tungsten arc welding and tightly controlled conditions it proved possible to produce weld metals with both

Cambridge, University of

421

Properties of low-alloy silicon — manganese steel with vandium, boron, and cerium  

Microsoft Academic Search

All heats except 6 and 7, to which 0.2% ferrocerium (nominal) was added, were deoxidized with aluminum (0.1%) on pouring. In heats 6 and 7 the amount of aluminum was 0.05% (nominal), added along with ferroeerium. The mechanical properties of the metal in the hot-rolled and hardened conditions are given in Table 2. The addition of 0.001 and 0.004% B

Yu I. Rubenchik; I. P. Medinskaya

1969-01-01

422

Ferromagnetic order in silicon-manganese alloys with phase separation  

SciTech Connect

A phenomenological model of high-temperature ferromagnetism in silicon-manganese alloys has been proposed taking into account phase separation in these alloys, where manganese-rich particles of the secondary phase (precipitate MnSi{sub 2-z} with z Almost-Equal-To 0.25-0.30) are formed inside a manganese-depleted matrix of almost pure silicon. Precipitate MnSi{sub 2-z} is considered as the silicide MnSi{sub 1.7} containing a certain number of magnetic defects whose origin is due to the presence of weakly hybridized 3d orbitals of manganese. The silicide MnSi{sub 1.7} is a weak band ferromagnet in which strong fluctuations of the spin density (paramagnons) are present at a temperature much higher than its Curie temperature. It has been shown that the ferromagnetic exchange interactions between the magnetic moments of defects in precipitate exists due to thermal excitations of the spin density and the ferromagnetic order can appear at a temperature much higher than the Curie temperature of the silicide. The spatial structures and characteristics of this order have been described in the framework of the proposed approach for both homogeneous bulk precipitate and precipitate particles of various shapes and sizes. The short-range magnetic order near the bulk phase transition has been analyzed taking into account inhomogeneities in the distribution of magnetic defects in precipitate. The experimental data on the magnetic properties of silicon-manganese alloys have been interpreted in terms of the theoretical results obtained in this work.

Men'shov, V. N., E-mail: vnmenshov@mail.ru; Tugushev, V. V., E-mail: tuvictor@mail.ru [National Research Centre Kurchatov Institute (Russian Federation)

2011-07-15

423

Metabolic activity of manganese during late gestation of first-litter gilts.  

PubMed

Four pairs of littermate Landrace gilts consuming either a low manganese (LMn) basal corn-soya diet (10 mg/kg) or a high Mn (HMn) supplement diet (84 mg/kg) were maintained in individual stainless steel metabolic cages throughout gestation. On the 100th day of gestation 200 microCi of 54Mn was administered intravenously. Total collection of feces and urine was conducted for a seven-day period. The sows were sacrificed after a three-week lactation period and several tissues excised. All samples were assayed for stable Mn content and 54Mn activity. Urinary excretion of 54Mn was negligible and not dependent on dietary Mn intake. Dietary Mn intake did not influence the rate of 54Mn elimination via the feces. The biological half-life (BHL) of the body Mn pool in late gestation averaged 54 days and was not influenced by treatment. The fecal Mn of endogenous origin was similar between treatments averaging 0.24 mg/d and yielded true absorption estimates of 1.31 and 1.61 mg/d for the LMn and HMn diets or 4.41% and 0.77% of dietary intake. PMID:1822330

Rhéaume, J A; Chavez, E R

1991-12-01

424

The mutagenicity and carcinogenicity of inorganic manganese compounds: a synthesis of the evidence.  

PubMed

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 an additional source in some regions. However, in occupationally exposed humans, inhalation of Mn is likely to be an important additional route. In general, Mn and its inorganic compounds are considered to possess low mutagenic or carcinogenic potential compared with some heavy metals. In this review, an up-to-date analysis of the available published studies on the carcinogenic and genotoxic potential of inorganic Mn is provided (organic Mn compounds are not considered). The current literature indicates that Mn may be weakly mutagenic in vitro and possibly clastogenic in vivo, with unknown genotoxic effects in humans; the possible mechanisms underlying these effects are discussed. The experimental evidence on carcinogenicity (quantitative increase in incidence of thyroid tumors in mice but not rats) does not provide any clear evidence, while the available occupational and environmental epidemiological evidence is equivocal as to whether exposure to inorganic Mn is associated with a significant cancer risk. Hence, it is concluded that there is insufficient evidence to indicate that inorganic Mn exposure produces cancer in animals or humans. PMID:22008092

Assem, Farida Louise; Holmes, Philip; Levy, Leonard Stephen

2011-01-01

425

Steel Industry Wastes.  

ERIC Educational Resources Information Center

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)

Schmidtke, N. W.; Averill, D. W.

1978-01-01

426

STEELS FOR NUCLEAR REACTORS  

Microsoft Academic Search

In building a nuclear reactor of any type, the stage is reached at which ; a decision must be made as to what steels can be used in construction of each ; plant component. Nuclear engineers have recognized the limitations of some of ; the common steels in nuclear environments and are pointing out ways the ; steelmaker should go

Beeghly

1960-01-01

427

Biological and physico-chemical formation of Birnessite during the ripening of manganese removal filters.  

PubMed

The efficiency of manganese removal in conventional groundwater treatment consisting of aeration followed by rapid sand filtration, strongly depends on the ability of filter media to promote auto-catalytic adsorption of dissolved manganese and its subsequent oxidation. Earlier studies have shown that the compound responsible for the auto-catalytic activity in ripened filters is a manganese oxide called Birnessite. The aim of this study was to determine if the ripening of manganese removal filters and the formation of Birnessite on virgin sand is initiated biologically or physico-chemically. The ripening of virgin filter media in a pilot filter column fed by pre-treated manganese containing groundwater was studied for approximately 600 days. Samples of filter media were taken at regular time intervals, and the manganese oxides formed in the coating were analysed by Raman spectroscopy, Electron Paramagnetic Resonance (EPR) and Scanning Electron Microscopy (SEM). From the EPR analyses, it was established that the formation of Birnessite was most likely initiated via biological activity. With the progress of filter ripening and development of the coating, Birnessite formation became predominantly physico-chemical, although biological manganese oxidation continued to contribute to the overall manganese removal. The knowledge that manganese removal in conventional groundwater treatment is initiated biologically could be of help in reducing typically long ripening times by creating conditions that are favourable for the growth of manganese oxidizing bacteria. PMID:25463936

Bruins, Jantinus H; Petrusevski, Branislav; Slokar, Yness M; Huysman, Koen; Joris, Koen; Kruithof, Joop C; Kennedy, Maria D

2015-02-01

428

Manganese reduction by microbes from oxic regions of the Lake Vanda (Antarctica) water column  

SciTech Connect

Depth profiles of metals in Lake Vanda, a permanently ice-covered, stratified Antarctic lake, suggest the importance of particulate manganese oxides in the scavenging, transport, and release of metals. Since manganese oxides can be solubilized by manganese-reducing bacteria, microbially mediated manganese reduction was investigated in Lake Vanda. Microbes concentrated from oxic regions of the water column, encompassing a peak of soluble manganese [Mn(II)], reduced synthetic manganese oxides (MnO{sub 2}) when incubated aerobically, Pure cultures of manganese-reducing bacteria were readily isolated from waters collected near the oxic Mn(II) peak. Based on phylogenetic analysis of the 16S rRNA gene sequence, most of the isolated manganese reducers belong to the genus Carnobacterium. Cultures of a phylogenetically representative strain of Carnobacterium reduced synthetic MnO{sub 2} in the presence of sodium azide, as was seen in field assays. Unlike anaerobes that utilize manganese oxides as terminal electron acceptors in respiration, isolates of the genus Carnobacterium reduced Mn(IV) via a diffusible compound under oxic conditions. The release of adsorbed trace metals accompanying the solubilization of manganese oxides may provide populations of Carnobacterium with a source of nutrients in this extremely oligotrophic environment.

Bratina, B.J.; Stevenson, B.S.; Schmidt, T.M. [Michigan State Univ., East Lansing, MI (United States); Green, W.J. [Miami Univ., Oxford, OH (United States). School of Interdisciplinary Studies

1998-10-01

429

Interactive effects of manganese and/or iron supplementation in adult women  

SciTech Connect

Evaluation of the practical significance of manganese-iron interactions has been hampered by the limited methodologies available to assess manganese status. Manganese status has not been monitored longitudinally in control studies with humans. Forty-eight women were recruited for a double blind 125-day supplementation study. After an initial 5-day baseline period, subjects were assigned to one of four treatments: placebo; 30 mg iron as ferrous fumarate daily; 15 mg manganese as an amino acid chelated manganese supplement daily or both the iron and manganese supplements daily. Dietary information, blood and 3-day urine samples were collected during the baseline period and after 20, 55, 85 and 120 days of consuming the supplements. Urinary manganese excretion ranged from 0.11 to 1.40 {mu}g/day. Serum manganese ranged from 0.16 to 1.92 {mu}g/l. Serum was also analyzed for iron, zinc, copper, ferritin and transferrin concentrations. Lymphocytes were isolated and manganese-dependent superoxide dismutase activity was determined as a new method to assess manganese status. Plasma cholesterol ranged from 126 to 229 mg/dl and HDL cholesterol ranged from 31 to 84 mg/dl. Plasma triglycerides were determined and LDL cholesterol was calculated by difference.

Davis, C.D.; Greger, J.L. (Univ. of Wisconsin, Madison (United States))

1991-03-15

430

Ceruloplasmin Alters the Tissue Disposition and Neurotoxicity of Manganese, but not its Loading onto Transferrin  

PubMed Central

Manganese (Mn) is a redox-active element, and whereas its uptake, disposition, and toxicity in mammals may depend in part on its oxidation state, the proteins affecting manganese oxidation state and speciation in vivo are not well known. Studies have suggested that the oxidase protein ceruloplasmin (Cp) mediates iron and manganese oxidation and loading onto plasma transferrin (Tf), as well as cellular iron efflux. We hypothesized that ceruloplasmin may also affect the tissue distribution and eventual neurotoxicity of manganese. To test this, aceruloplasminemic versus wild-type mice were treated with a single i.p. 54Mn tracer dose, or elevated levels of manganese subchronically (0, 7.5, or 15 mg Mn/kg s.c., three doses per week for 4 weeks), and evaluated for transferrin-bound manganese, blood manganese partitioning, tissue manganese disposition, and levels of brain glutathione, thiobarbituric acid reactive substances (TBARS), and protein carbonyls as measures of oxidative stress, and open arena activity. Results show that ceruloplasmin does not play a role in the loading of manganese onto plasma transferrin in vivo, or in the partitioning of manganese between the plasma and cellular fractions of whole blood. Ceruloplasmin did, however, affect the retention of manganese in blood and its distribution to tissues, most notably kidney and to a lesser extent brain and lung. Results also indicate that ceruloplasmin interacted with chronic elevated manganese exposures to produce greater levels of brain oxidative stress. These results provide evidence that metal oxidase proteins play an important role in altering neurotoxicity arising from elevated manganese exposures. PMID:19005224

Jursa, Thomas; Smith, Donald R.

2009-01-01

431

Potential of dandelion ( Taraxacum officinale) as a bioindicator of manganese arising from the use of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline  

Microsoft Academic Search

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

L. Normandin; G. Kennedy; J. Zayed

1999-01-01

432

Removal of manganese by chelating agents from brain and liver of manganese treated rats: as in vitro and an in vivo study.  

PubMed

Some chelating agents were examined for their ability to remove manganese from brain and liver (in vivo) and their sub-cellular fractions (in vitro), of rats pretreated with manganese sulphate. Nitrilotriacetic acid (NTA), 1,2-cyclohexylenedinitrilotetraacetic acid (CDTA) and diethylenetriaminepentaacetic acid (DTPA) were extremely effective in vivo while CDTA and p-aminosalicylic acid (PAS) were efficient in vitro. PMID:1209652

Tandon, S K; Singh, J

1975-11-01

433

Hot Tearing Modeling: A Microstructural Approach Applied to Steel Solidification  

NASA Astrophysics Data System (ADS)

Hot tearing during solidification processes has been deeply investigated in past and recent years through testing, modeling, and development of a number of macroscopic hot tearing criteria. The objective is predicting the crack occurrence during industrial solidification processes, which, in the steel production, are mainly ingot and continuous casting. The present work is inspired by the criterion proposed in the work of Bellet et al.[1] called CBC criterion, from which the methodological approach and experimental data used for calibration, related to nine carbon steels, have been derived. The proposed hot tearing criterion adopts as parameters: primary and secondary arm spacing, the mechanical resistance near the solidus temperature, the solidification parameters G (gradient) and v (dendrite tip velocity), the brittle range extension in the dendritic front and the temperature of formation of manganese sulfides. The new formulation is an attempt to substitute to brittle temperature range and steel content, appearing in the CBC criterion, the dendritic structure characteristics, in the aim of: (a) moving toward a generalized expression of the cracking index applicable to different steel classes; (b) introducing the dependence of the crack susceptibility on the cooling conditions. The agreement of the new hot tearing index values with the experimental ones is of the same kind as that of the CBC criterion, indicating that the parameters and the dependences adopted in the new criterion make a sense. Further study and experimental work are needed to assess the influence of the microstructure morphology on the hot cracking sensitivity and to check the suitability of the approach to a wider range of steel compositions.

Ridolfi, Maria Rita

2014-08-01

434

EAST ELEVATION, LTV STEEL (FORMERLY REPUBLIC STEEL), 8" BAR MILL, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

EAST ELEVATION, LTV STEEL (FORMERLY REPUBLIC STEEL), 8" BAR MILL, BUFFALO PLANT. VIEW LOOKING SOUTHWEST FROM ROLL SHOP. 8" BAR MILL DESIGNED AND BUILT BY DONNER STEEL CO. (PREDECESSOR OF REPUBLIC), 1919-1920. FOR DESCRIPTION OF ORIGINAL MILL SEE "IRON AGE", 116\\4 (23 JULY 1925): 201-204. - LTV Steel, 8-inch Bar Mill, Buffalo Plant, Buffalo, Erie County, NY

435

Nanoscale surface analysis on second generation advanced high strength steel after hot dip galvanizing.  

PubMed

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

Arndt, M; Duchoslav, J; Preis, K; Samek, L; Stifter, D

2013-09-01

436

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide  

USGS Publications Warehouse

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.

Balistrieri, L.S.; Chao, T.T.

1990-01-01

437

Manganese reduction and its stabilization in the rock record  

NASA Astrophysics Data System (ADS)

Manganese oxides are abundant and highly reactive electron acceptors present within many environments. Their occurance is intimately tied to the availability of oxygen, as only O2 and oxygen-derived species such as superoxide and peroxide can oxidize reduced Mn(II). Because Mn2+ is soluble and Mn3+ and Mn4+ readily undergo hydrolysis to form insoluble precipitates, the record of manganese in sedimentary deposits can yield interesting insights into the history of atmospheric oxygen--the largest manganese deposits in Earth history (approximately 2.2 billion years ago) are associated with the rise of oxygen. From studying modern environments, we understand that manganese is concentrated in sediments by the oxidation and deposition of Mn(IV) minerals; however, our observations of the geologic record show diagenetic stabilization of only Mn(II) carbonate or mixed Mn(II)-Mn(III) oxide minerals--all Mn(IV)-oxide phases in ancient samples are associated with modern weathering and oxidation processes. Reduction is a key element within the manganese cycle, yet the (bio)geochemical processes responsible for the formation of mixed Mn(II)-Mn(III) minerals have not been fully elucidated. To better understand how manganese is converted from insoluble Mn(IV) oxide to these Mn(II/III)-bearing phases, we investigated secondary mineral precipitates which form during and after Mn(IV)-oxide reduction using a well-studied metal-reducing bacteria, Shewanella oneidensis MR-1. To examine changes in Mn mineralogy and oxidation state during the progression of Mn(IV) reductive dissolution/transformation by S. oneidensis, we utilized a flow through reactor system allowing for in-situ and real time x-ray absorption spectroscopy (XAS) measurements. We also confirmed mineral phases using XRD and FTIR spectrometry. Our experiments reveal that when solution phosphate concentrations are high, a Mn(II) phosphate phase quickly forms as a secondary precipitate during complete reduction of Mn(IV) oxides. However, when phosphate is excluded, either complete or incomplete reduction may ensue. When incomplete reduction occurs, the dominant solid phase at the end of experimentation is a Mn(III)-bearing oxide, but in experiments with complete Mn(VI) reduction, we observe either the formation of Mn carbonate(s), or complete dissolution (no secondary precipitates) depending on the presence of organic ligands and carbonate chemistry of the media. Accordingly, we will discuss (bio)geochemical mechanisms which may explain Mn stabilization within sediments as Mn(II)-carbonate and Mn(III)-dominated minerals, and relate them to observations of Mn within the rock record.

Johnson, J. E.; Savalia, P.; Kocar, B. D.; Webb, S. M.; Nealson, K. H.; Fischer, W. W.

2013-12-01

438

Preparation of the first manganese(III) and manganese(IV) azides.  

PubMed

Fluoride-azide exchange reactions of Me3SiN3 with MnF2 and MnF3 in acetonitrile resulted in the isolation of Mn(N3)2 and Mn(N3)3 ?CH3CN, respectively. While Mn(N3)2 forms [PPh4]2[Mn(N3)4] and (bipy)2Mn(N3)2 upon reaction with PPh4N3 and 2,2'-bipyridine (bipy), respectively, the manganese(III) azide undergoes disproportionation and forms mixtures of [PPh4]2[Mn(N3)4] and [PPh4]2[Mn(N3)6], as well as (bipy)2Mn(N3)2 and (bipy)Mn(N3)4. Neat and highly sensitive Cs2[Mn(N3)6] was obtained through the reaction of Cs2MnF6 with Me3SiN3 in CH3CN. PMID:25044947

Haiges, Ralf; Buszek, Robert J; Boatz, Jerry A; Christe, Karl O

2014-07-28

439

Migration of Mn cations in delithiated lithium manganese oxides.  

PubMed

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

Kan, Yongchun; Hu, Yuan; Lin, Chi-Kai; Ren, Yang; Sun, Yang-Kook; Amine, Khalil; Chen, Zonghai

2014-10-14

440

Cathodic behavior of alkali manganese oxides from permanganate  

SciTech Connect

Extensive research is currently underway to find promising candidates for cathode materials in lithium secondary batteries, and a manganese oxide that behaved like the layered LiCoCO{sub 2} would be a prime candidate for this application because of its high free-energy of reaction with lithium and relatively low cost. The reaction of potassium, sodium, and lithium permanganate in water at 170 C leads directly to potassium, sodium, and lithium manganese dioxides, A{sub y}MnO {center_dot} nH{sub 2}O, with a R{bar 3}m rhombohedral structure. These crystalline layered structures after dehydration readily and reversibly react with lithium through an intercalation mechanism. The capacity for lithium is a function of the alkali ion present, and the larger potassium ion maintains the capacity best. For lithium there is a tendency to convert to the spinel structure which leads to loss of capacity.

Chen, R.; Whittingham, M.S. [State Univ. of New York, Binghamton, NY (United States)

1997-04-01

441

Manganese-based MRI contrast agents: past, present and future  

PubMed Central

Paramagnetic and superparamagnetic metals are used as contrast materials for magnetic resonance (MR) based techniques. Lanthanide metal gadolinium (Gd) has been the most widely explored, predominant paramagnetic contrast agent until the discovery and association of the metal with nephrogenic systemic fibrosis (NSF), a rare but serious side effects in patients with renal or kidney problems. Manganese was one of the earliest reported examples of paramagnetic contrast material for MRI because of its efficient positive contrast enhancement. In this review, manganese based contrast agent approaches are discussed with a particular emphasis on their synthetic approaches. Both small molecules based typical blood pool contrast agents and more recently developed novel nanometer sized materials are reviewed focusing on a number of successful molecular imaging examples. PMID:22043109

Pan, Dipanjan; Schmieder, Anne H.; Wickline, Samuel A.; Lanza, Gregory M.

2011-01-01

442

Manganese oxide nanowires, films, and membranes and methods of making  

DOEpatents

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.

Suib, Steven Lawrence (Storrs, CT); Yuan, Jikang (Storrs, CT)

2008-10-21

443

First principle study of manganese doped cadmium sulphide sheet  

SciTech Connect

First-principle electronic structure calculations for cadmium sulphide (CdS) sheet in hexagonal phase, with Manganese substitution and addition, as well as including the Cd defects, are investigated. The lattice constants calculated for CdS sheet agrees fairly well with results reported for thin films experimentally. The calculations of total spin density of states and partial density of states in different cases shows substantial magnetic dipole moments acquired by the sheet. A magnetic dipole moment 5.00612 ?{sub B} and band gap of the order 1 eV are found when cadmium atom is replaced by Manganese. The magnetism acquired by the sheet makes it functionally important candidate in many applications.

Kumar, Sanjeev, E-mail: drskumar11@gmail.com [Department of Physics, St. Bede's College, Shimla-171002 (India); Kumar, Ashok; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University, Shimla-171005 (India)

2014-04-24

444

Facile uptake of manganese(III) by apotransferrin: possible origin of manganism.  

PubMed

We have investigated the mechanism of manganese ion uptake by apo-transferrin using a capillary electrophoresis method, and obtained clear evidence that oxidation state +3 and the binuclear unit of a manganese chelate are essential factors for the facile uptake by apotransferrin, similar to that observed for Fe(III) chelates. These results may give valuable information to understand the pathogenesis of manganism and to develop new countermeasures for the neurotoxicity by manganese ions. PMID:18386506

Abe, Keita; Chiba, Yuji; Nishida, Yuzo

2008-01-01

445

Environmental Manganese and Cancer Mortality Rates by County in North Carolina: An Ecological Study  

Microsoft Academic Search

Manganese is an element essential for health in trace amounts, but toxic at higher exposures. Since manganese is replacing\\u000a lead in gasoline globally, evaluation of potential cancer effects is essential. To determine whether environmental manganese\\u000a is related to cancer at the county level in North Carolina (n?=?100 counties; North Carolina 2000 population = 8,049,313), we carried out an ecological study

John G. Spangler; Jeffrey C. Reid

2010-01-01

446

Determination of manganese in ores by activation analysis using a californium-252 neutron source  

Microsoft Academic Search

A252Cf neutron source has been used to analyse manganese in ores such as pyrolusite, rodonite (manganese silicate) and blends\\u000a used in dry-batteries. Samples with about 150 mg and standards of manganese dioxide were irradiated for about 20 min and counted\\u000a using a well-type NaI(Tl) scintillation counter and scaler, with or without pulse-height discriminator between the detector\\u000a and the scaler. The

A. Cardoso; F. W. Lima

1977-01-01

447

Manganese (Mn) and Iron (Fe): Interdependency of Transport and Regulation  

Microsoft Academic Search

Manganese (Mn) and iron (Fe) are transition metals that are crucial to the appropriate growth, development, function, and\\u000a maintenance of biological organisms. Because of their chemical similarity, in organisms ranging from bacteria to mammals they\\u000a share and compete for many protein transporters, such as the divalent metal transporter-1. As such, during conditions of low\\u000a Fe, abnormal Mn accumulation occurs. Conversely,

Vanessa A. Fitsanakis; Na Zhang; Stephanie Garcia; Michael Aschner

2010-01-01

448

Manganese oxide–carbon composite as supercapacitor electrode materials  

Microsoft Academic Search

Nano-sized manganese oxide (Mn2O3) was incorporated homogeneously in templated mesoporous carbon to prepare Mn2O3–carbon nanocomposites, which were used as supercapacitor electrodes. Cyclic voltammetry was employed to investigate the electrochemical properties of the composite materials in an aqueous electrolyte under different scan rates. Results showed that templated mesoporous carbon with layered graphene domains holds a great promise for high-rate supercapacitor applications.

Li Li Zhang; Tianxin Wei; Wenjuan Wang; X. S. Zhao

2009-01-01

449

Electronic and magnetic properties of manganese impurities in aluminum  

Microsoft Academic Search

We studied the electronic structure of manganese impurities in a fcc aluminum matrix by means of calculations for a free MnAl18 cluster. Our ab initio self-consistent computations employed the Rajagopal-Singhal-Kimball local-spin-density potential and a symmetrized Gaussian-orbital basis. The local and cluster magnetic moments are, respectively, 1.74muB and 1.0muB. Substantial screening of the Mn moment by opposite polarization of the surrounding

D. Bagayoko; N. Brener; D. Kanhere; J. Callaway

1987-01-01

450

Electronic structure of chromium and manganese impurities in copper  

Microsoft Academic Search

We have performed self-consistent calculations of the electronic structures of chromium and manganese impurities in an fcc copper matrix. The calculations employed a linear combination of Gaussian orbitals procedure applied to the 19-atom clusters CrCu12Cu6 and MnCu12Cu6. No shape approximation was made to the potential which was chosen according to the local-spin-density functional approximation. We discuss the electronic levels and

D. Bagayoko; P. Blaha; J. Callaway

1986-01-01

451

Manganese: Recent advances in understanding its transport and neurotoxicity  

SciTech Connect

The present review is based on presentations from the meeting of the Society of Toxicology in San Diego, CA (March 2006). It addresses recent developments in the understanding of the transport of manganese (Mn) into the central nervous system (CNS), as well as brain imaging and neurocognitive studies in non-human primates aimed at improving our understanding of the mechanisms of Mn neurotoxicity. Finally, we discuss potential therapeutic modalities for treating Mn intoxication in humans.

Aschner, Michael [Departments of Pediatrics, Pharmacology, and Kennedy Center for Research on Human Development, B-3307 Medical Center North, Vanderbilt University, School of Medicine, Nashville, TN 37232-2495 (United States)]. E-mail: Michael.Aschner@vanderbilt.edu; Guilarte, Tomas R. [Neurotoxicology and Molecular Imaging Laboratory, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (United States); Schneider, Jay S. [Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA (United States); Zheng Wei [School of Health Sciences, Purdue University, West Lafayette, IN (United States)

2007-06-01

452

Optical and structural properties of manganese sulfide thin films  

Microsoft Academic Search

Highly transparent crystalline manganese sulfide (?-MnS) thin films were prepared on glass substrate by chemical bath deposition (CBD) method at room temperature (27°C). The refractive index n(?), extinction coefficient k(?) and film thickness t are evaluated from spectrophotometric transmittance spectrum by using envelope method. The optical band gap of the film was estimated to be 3.88eV. XRD measurements show that

C. Gümüs; C. Ulutas; Y. Ufuktepe

2007-01-01

453

Correction of severe manganese deficiency in wheat with chemical fertilizers  

Microsoft Academic Search

Summary Manganese, N and P fertilizers were applied to wheat in field experiments on a soil so deficient in Mn that it caused the wheat to die before heading. Yields of wheat were increased linearly by soil banded Mn to 44.8 kg\\/ha, giving a yield of 3.03 tonnes\\/ha. Yields were increased to a lesser extent by foliar-applied Mn and least

P. B. Hoyt; G. G. S. Myovella

1979-01-01

454

Giant magnetoresistance of manganese oxides with a layered perovskite structure  

Microsoft Academic Search

MANGANESE oxides with the cubic perovskite structure (typified by LaMnO3) have stimulated considerable interest because of their magnetoresistive properties1-9 they exhibit extremely large changes in electrical resistance in response to applied magnetic fields, a property that is of technological relevance for the development of magnetic memory and switching devices. But for such applications to be viable, great improvements will be

Y. Moritomo; A. Asamitsu; H. Kuwahara; Y. Tokura

1996-01-01

455

Accumulation and uptake of manganese in a hyperaccumulator Phytolacca americana  

Microsoft Academic Search

Phytolacca americana (pokeweed) has been found to be a new manganese hyperaccumulator plant by means of field surveys on Mn-rich soils and by Hydroponics experiments. This species not only has remarkable tolerance to Mn but also has extraordinary uptake and accumulation capacity for this element. The maximum Mn concentration in the leaf dry matter was 8000mg\\/g on Xiangtan Mn tailings

Yuan Min; Tie boqing; Tang Meizhen; Isao Aoyama

2007-01-01

456

Mechanisms of hydrogen sulfide removal with steel making slag.  

PubMed

In the present study, we experimentally investigated the removal of hydrogen sulfide using steel-making slag (SMS) and clarified the mechanism of hydrogen sulfide removal with the SMS. The results proved that SMS is able to remove hydrogen sulfide dissolved in water, and the maximum removal amount of hydrogen sulfide per unit weight of the SMS for 8 days was estimated to be 37.5 mg S/g. The removal processes of hydrogen sulfide were not only adsorption onto the SMS, but oxidation and precipitation as sulfur. The chemical forms of sulfide adsorbed onto the SMS were estimated to be sulfur and manganese sulfide in the ratio of 81% and 19%, respectively. It is demonstrated here that the SMS is a promising material to remediate organically enriched coastal sediments in terms of removal of hydrogen sulfide. Furthermore, using SMS is expected to contribute to development of a recycling-oriented society. PMID:22894171

Kim, Kyunghoi; Asaoka, Satoshi; Yamamoto, Tamiji; Hayakawa, Shinjiro; Takeda, Kazuhiko; Katayama, Misaki; Onoue, Takasumi

2012-09-18

457

Effect of aging on properties of pressure vessel steels  

SciTech Connect

Manganese-molybdenum-nickel steels are used in nuclear pressure vessels operating at temperatures up to 350/sup 0/C. The effects of thermal ageing in the temperature range 300-550/sup 0/C for durations up to 2 x 10/sup 4/ h have been studied in conventionally quenched and tempered and simulated heat-affected-zone (HAZ) microstructural conditions. Quantitative fractography and Auger spectroscopy have been used to relate changes in mechanical properties with changes in fracture mode and grain boundary chemistry. Aging increases the ductile-brittle transition temperature by an amount dependent on material, prior heat treatment, aging temperature and time. Embrittlement is associated with segregation of phosphorus to grain boundaries and is modelled using McLean's approach to equilibrium segregation.

Druce, S.G.; Gage, G.; Jordan, G.

1986-04-01

458

Effect of manganese deficiency on wound healing glycosaminoglycans  

SciTech Connect

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.

Shetlar, M.R.; Shetlar, C.L. (Texas Tech Univ., Lubbock (United States))

1991-03-15

459

Assessing dust exposure in an integrated iron and steel manufacturing plant in South India.  

PubMed

A study to monitor and estimate respirable particulate matter (RPM), toxic trace metal concentrations in the work environment was carried out in different sections of an integrated steel manufacturing industry. The average RPM concentration observed varied according to the section blast furnace was 2.41 mg/m;{3}; energy optimization furnace, 1.87 mg/m;{3}; sintering plant, 0.98 mg/m;{3}; continuous casting machine, 1.93 mg/m;{3}. The average trace metal concentration estimated from the RPM samples like iron, manganese, lead and chromium did not exceed ACGIH prescribed levels. PMID:18413935

Ravichandran, B; Krishnamurthy, V; Ravibabu, K; Raghavan, S; Rajan, B K; Rajmohan, H R

2008-01-01

460

Thermodynamics of the oxygen solutions in manganese-containing Fe-Co melts  

NASA Astrophysics Data System (ADS)

Thermodynamic analysis of the oxygen solutions in manganese-containing Fe-Co melts has been performed. The equilibrium constants of deoxidation reaction of iron-cobalt melts with manganese, the activity coefficients during infinity dilution, and the interaction parameters in various melts are found. During the deoxidation of manganese-containing Fe-Co melts, the oxide phase contains FeO and CoO along with MnO. The compositions of the oxide phase above Fe-Co-Mn-O melts are calculated. When the cobalt and manganese contents in the melts increase, the mole fraction of manganese oxide increases, and it approaches 1 in the case of pure cobalt. The dependences of the oxygen solubility in the melts on the cobalt and manganese contents are calculated. The deoxidizing capacity of manganese increases substantially with increasing cobalt content in the melt. The curves of oxygen solubility in Fe-Co melts have minima, whose values shift toward low manganese content in a melt. The manganese contents are determined at the minimum points in the oxygen solubility curves, and the corresponding minimum oxygen contents are found.

Aleksandrov, A. A.; Dashevskii, V. Ya.

2014-01-01

461

Effects of Chronic Manganese Exposure on Cognitive and Motor Functioning in Non-Human Primates  

PubMed Central

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

Schneider, Jay S.; Decamp, Emmanuel; Koser, Amy Jo; Fritz, Stephanie; Gonczi, Heather; Syversen, Tore; Guilarte, Tomás R.

2007-01-01

462

Solubilisation effect of spent wash on oxide-ores of manganese and iron.  

PubMed

Samples of iron ore (haematite) and manganese ore (pyrolusite) of known compositions were equilibrated with aliquots of analysed sample of spent wash. The concentrations of iron(II), iron(III), complexed iron, manganese(II) ions and complexed Mn-ions were determined after increasing durations. One litre of the spent wash was found to extract out 141 mg of total iron and 161 mg of total manganese. In case of iron, the predominance was of iron(II) (92%), whereas in case of manganese it was of the complexed form (95%). PMID:24202955

Pervez, S; Pandey, G S

1991-09-01

463

Elimination of impurity-induced embrittlement in steel. Part 2. High-temperature cracking - stress-relief and creep cracking  

SciTech Connect

The effects of compositional and microstructural parameters on the temper embrittlement susceptibility of Ni-Cr and Cr-Mo type steels have been investigated. Results show the three principal variables affecting the embrittlement behavior of the steels to be the grain boundary composition, grain size and the hardness. Unified embrittlement equations have been developed relating the combined effect of the the three variables to the transition temperature of the steel. For Cr-Mo type steels not containing any nickel, phosphorous was found to be the major impurity responsible for temper embrittlement. Manganese and silicon were also found to be detrimental due to their interactive effects with phosphorous. The temperature of the transformation product (bainite vs martensite) was not found to significantly influence the embrittlement susceptibility of the Cr-Mo steels. Auger electron spectroscopic analysis of the surface layers of samples of the various steels heated to elevated temperatures has also been completed. Results of this analysis show that this technique can be successfully applied for determining the kinetics of segregation processes in complex steels and to understand the effects of minor alloying elements on the segregation behavior of impurity elements.

Pope, D.P.; Abiko, K.A.; Bodnar, R.L., Wilkinson, D.S.; McMahon, C.J. Jr.; Dobbs, R.; Gentner, D.

1980-09-01

464

Plan-view and cross-sectional characterization of thiourea-treated phosphorus-added steel surface.  

PubMed

The galvanizing reaction is retarded when phosphorus-added steel is used as a substrate. We have found that both the galvanizing and the galvannealing reactions are highly promoted when thiourea solution is coated on the cold-rolled steel surface before the annealing process. Both a plan-view and cross-sectional characterization of thiourea-coated steel was performed using low-voltage scanning electron microscopy and a focused ion beam. A fine grain structure is formed in the surface region of approximately 1 microm in thickness. In this region, (Mn, Fe)S particles are formed by the reaction between sulphur from thiourea and manganese from steel. These (Mn, Fe)S particles have a pinning effect on the cold-rolled steel grains and greatly retard recrystallization when the steel is annealed. It is concluded that the promotion of the galvannealing reaction is due to the increased diffusion paths of zinc and iron materialized by the fine grain structure of the thiourea-coated steel. PMID:15582964

Sato, Kaoru; Sakurai, Michitaka; Taira, Shoichiro; Hamada, Etsuo

2004-01-01

465

Changes in brain regional manganese and magnesium levels during postnatal development: modulations by chronic manganese administration.  

PubMed

Manganese (Mn) and magnesium (Mg) levels in hypothalamus, cerebellum, pons and medulla, striatum, midbrain, and cerebral cortex of control and Mn-treated (10 mg MnCl2.4H2O per ml of drinking water) rats during postnatal development were studied using instrumental neutron activation analysis. The age-dependent Mn accumulation showed regional variation: at day 5, this accumulation was most marked in striatum (12.05 micrograms/g wet weight) but least marked in cerebral cortex (0.85 micrograms/g wet weight). By day 10, pons and medulla, and hypothalamus were regions with, respectively, the highest (4.73 micrograms/g wet weight) and the lowest (0.52 micrograms/g wet weight) Mn levels. By contrast, brain regional Mn variations were less pronounced in weanling and adult rats. The age-dependent Mg accumulation showed regional variation at day 5, being most marked in pons and medulla (720 micrograms/g wet weight) and least marked in cerebral cortex (295 micrograms/g wet weight). Mg levels in all regions decreased after day 5; by day 120, only Mg level in cerebral cortex was lower than levels in other regions (the latter being very similar). In general, the age-related decreases in Mn and Mg levels paralleled the decreases in water content and increases in tissue weight, suggesting that the maturation of the blood-brain barrier may play important role(s) in brain Mn and Mg homeostasis. Chronic Mn-treatment from conception onwards altered the regional Mn and Mg distribution patterns during development. Our results are consistent with the hypothesis that chronic Mn toxicity exerts modulatory effects on brain regional metabolism and homeostasis of Mn and other metals during development. PMID:1608364

Chan, A W; Minski, M J; Lim, L; Lai, J C

1992-03-01

466

Kinetics of manganese transport and gene expressions of manganese transport carriers in Caco-2 cell monolayers.  

PubMed

Two experiments were conducted to investigate the kinetics of manganese (Mn) transport in Caco-2 cell monolayers and the gene expressions of Mn transport carriers in apical (AP) and basolateral (BL) membranes. In experiment 1, the cells were treated with the medium containing 146 ?mol/L of Mn (MnSO4·H2O). Both the uptake and transport of Mn from AP-BL or from BL-AP at different time-points were assessed to determine the optimal time for kinetics of Mn transport. The transport of Mn increased linearly with higher efficiency values in AP-BL than in BL-AP direction, however, the uptake of Mn revealed an asymptotic pattern within 120 min. In experiment 2, the kinetics of Mn transport in AP-BL was determined with media containing Mn concentrations from 0 to 2,500 ?mol/L at 40 and 120 min, respectively, and mRNA levels of divalent metal transporter 1 (DMT1) and ferroportin (FPN1) were determined in Caco-2 cells treated with the medium containing 0 or 800 ?mol/L of Mn for 120 min. The kinetics of Mn transport showed a carrier-mediated process when Mn concentrations were lower than 1,000 ?mol/L and a linear increment when Mn concentrations exceeded 1,000 ?mol/L at either 40 or 120 min. Mn treatment decreased (P < 0.01) DMT1 mRNA level and increased (P < 0.01) FPN1 mRNA level. The results from the present study suggested that Mn transport in AP-BL fit both carrier-mediated saturable and non-saturable diffusion processes, and Mn transport carriers DMT1 and FPN1 mediate the apical uptake and basolateral exit of Mn in Caco-2 cells. PMID:23996061

Li, Xiaoli; Xie, Jingjing; Lu, Lin; Zhang, Liyang; Zhang, Lingyan; Zou, Yaxue; Wang, Qiuyue; Luo, Xugang; Li, Sufen

2013-12-01

467

[Effects of manganese on antioxidant system of manganese-hyperaccumulator Phytolacca americana L.].  

PubMed

A hydroponic experiment was conducted to study the growth, manganese (Mn) accumulation, lipid peroxidation, H2O2 concentration, and antioxidant system of Phytolacca americana L. exposed to different concentration Mn. With increasing Mn concentration in the medium, the plant Mn content increased significantly, and the Mn accumulation was in the sequence of leaf > stem > root. Comparing with the control, low concentration (5 mmol x L(-1)) Mn promoted the plant growth, decreased the leaf H2O2 concentration, and had less effects on the leaf malondialdehyde (MDA) content, while high concentration (> or = 10 mmol x L(-1)) Mn led to a remarkable increase of leaf H2O2 and MDA contents, indicating an evident oxidative damage occurred in leaves. The activities of ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase and the content of reduced ascorbate increased with increasing Mn concentration, while the SOD activity was inhibited significantly at 5 mmol x L(-1) of Mn but enhanced at > or = 10 mmol x L(-1) of Mn. The activities of catalase and peroxidase and the content of reduced glutathione increased at 5-10 mmol x L(-1) of Mn but dropped markedly at 20 mmol x L(-1) of Mn. All the results suggested that the Mn-induced oxidative damage and Mn accumulation might be responsible for the growth inhibition of P. americana plants at high Mn exposure, and the increase of antioxidative enzyme activities and low molecular antioxidant contents was, at least partly, contributed to the Mn tolerance and hyperaccumulation of P. americana. However, due to their different Mn concentration-dependent change modes, these antioxidants played different roles in the Mn tolerance of P. americana. PMID:20077708

Wang, Hai-Hua; Feng, Tao; Peng, Xi-Xu; Yan, Ming-Li; Tang, Xin-Ke

2009-10-01

468

Structural Amorphous Steels  

NASA Astrophysics Data System (ADS)

Recent advancement in bulk metallic glasses, whose properties are usually superior to their crystalline counterparts, has stimulated great interest in fabricating bulk amorphous steels. While a great deal of effort has been devoted to this field, the fabrication of structural amorphous steels with large cross sections has remained an alchemist’s dream because of the limited glass-forming ability (GFA) of these materials. Here we report the discovery of structural amorphous steels that can be cast into glasses with large cross-section sizes using conventional drop-casting methods. These new steels showed interesting physical, magnetic, and mechanical properties, along with high thermal stability. The underlying mechanisms for the superior GFA of these materials are discussed.

Lu, Z. P.; Liu, C. T.; Thompson, J. R.; Porter, W. D.

2004-06-01

469

Elements of Steel  

NSDL National Science Digital Library

This resource from the AMERICAN EXPERIENCE Web site, which contains both an interactive activity and illustrated text, looks at the composition of different types of steel and their impact on technology.

2008-02-01

470

Manganese and iron both influence the shoot transcriptome of Typha angustifolia despite distinct preference towards manganese accumulation  

Microsoft Academic Search

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

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

471

Iron and manganese oxide mineralization in the Pacific  

USGS Publications Warehouse

Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. Iron and manganese deposits occur in five forms: nodules, crusts, cements, mounds and sediment-hosted stratabound layers. Seafloor oxides show a wide range of compositions from nearly pure iron to nearly pure manganese end members. Fe/Mn ratios vary from about 24 000 (up to 58% elemental Fe) for hydrothermal seamount ironstones to about 0.001 (up to 52% Mn) for hydrothermal stratabound manganese oxides from active volcanic arcs. Hydrogenetic Fe-Mn crusts that occur on most seamounts in the ocean basins have a mean Fe/Mn ratio of 0.7 for open-ocean seamount crusts and 1.2 for continental margin seamount crusts. Fe-Mn nodules of potential economic interest from the Clarion-Clipperton Zone have a mean Fe/Mn ratio of 0.3, whereas the mean ratio for nodules from elsewhere in the Pacific is about 0.7. Crusts are enriched in Co, Ni and Pt and nodules in Cu and Ni, and both have significant concentrations of Pb, Zn, Ba, Mo, V and other elements. In contrast, hydrothermal deposits commonly contain only minor trace metal contents, although there are many exceptions, for example, with Ni contents up to 0.66%, Cr to 1.2%, and Zn to 1.4%. Chondrite-normalized REE patterns generally show a positive Ce anomaly and abundant ??REEs for hydrogenetic and mixed hydrogenetic-diagenetic deposits, whereas the Ce anomaly is negative for hydrothermal deposits and ??REE contents are low. However, the Ce anomaly in crusts may vary from strongly positive in East Pacific crusts to slightly negative in West Pacific crusts, which may reflect the redox conditions of seawater. The concentration of elements in hydrogenetic Fe-Mn crusts depends on a wide variety of water column and crust surface characteristics, whereas concentration of elements in hydrothermal oxide deposits depends of the intensity of leaching, rock types leached, and precipitation of sulphides at depth in the hydrothermal system.

Hein, J.R.; Koschinsky, A.; Halbach, P.; Manheim, F. T.; Bau, M.; Kang, J.-K.; Lubick, N.

1997-01-01

472

Life after Steel  

ERIC Educational Resources Information Center

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…

Mangan, Katherine

2013-01-01

473

Detection and determination of solute carbon in grain interior to correlate with the overall carbon content and grain size in ultra-low-carbon steel.  

PubMed

In this study, every effort was exerted to determine and accumulate data to correlate microstructural and compositional elements in ultra-low-carbon (ULC) steels to variation of carbon content (12-44 ppm), manganese (0.18-0.36%), and sulfur (0.0066-0.001%). Quantitative analysis of the ULC steel using optical microscope, scanning electron microscope, transmission electron microscope, and three-dimensional atom probe revealed the decrease of grain size and dislocation density with the increase of carbon contents and/or increase of the final delivery temperature. For a given carbon content, the grain interior carbon concentration increases as the grain size increases. PMID:23920177

Dong, Jiling; He, Yinsheng; Lee, Chan-Gyu; Lee, Byungho; Yoon, Jeongbong; Shin, Keesam

2013-08-01

474

Gas quenching tool steels  

SciTech Connect

Alloy steel parts are increasingly being heat treated in vacuum furnaces using gas overpressure quenching. The maximum gas pressure typically is 6 bar absolute, and nitrogen usually is the quenching gas. This is adequate for through-hardening tools and other parts made of high-speed, hot-work, and, to a limited extent, cold-work steels. However, the quenching speed (cooling rate) is often too low to permit the successful heat treating of: (1) tools and other parts made of medium- and low-alloy steels; (2) large forging and plastics molding dies made of medium-alloy steels; (3) large, densely loaded batches of identical parts; (4) parts made of austenitic steels and alloys that require a rapid quench after they are solution annealed; and (5) cold-work steel tools and other parts having diameters larger than 100mm (4 in.). Oil quenching is required for these applications. However, its use increases the potential for cracking and can cause distortion. To extend gas quenching to these materials, Leybold Durferrit GmbH, Hanau, Germany, has developed a new generation of vacuum furnaces that combines convective heating and high-pressure gas quenching at pressures up to 20 bar (2 MPa, 290 psi).

Heilmann, P. (Leybold Durferrit GmbH, Hanau (Germany)); Zenker, W.R. (Leybold Technologies Inc., Enfield, CT (United States))

1993-02-01

475

Effects of Magnetic and Non-Magnetic Impurities in MgB2: A Point-Contact Study of Single Crystals  

NASA Astrophysics Data System (ADS)

We studied the effects of chemical substitutions, either magnetic (Mn) or non-magnetic (Al, C), on the energy gaps of MgB2 by means of directional point-contact spectroscopy (PCS) in state-of-the-art single crystals. Here we discuss two noticeable cases, i.e. Mg1-xMnxB2 crystals with x up to 0.015, and Mg1-xAlxB2 crystals with x up to 0.32. In both cases, we used a pressure-less PCS technique in which a thin Au wire is put in contact with the side surface of the crystal by means of a small drop of Ag paint. The gaps ?? and ?? were obtained through a two-band Blonder-Tinkham-Klapwijk (BTK) fit of the Andreev-reflection conductance curves of the resulting contacts. Both in Mn- and Al-doped MgB2, the gaps decrease on decreasing the critical temperature of the contacts, Tc^A (at which the Andreev-reflection structures disappear), but remain clearly distinct down to Tc^A˜10 K. Once analysed within the two-band Eliashberg theory, the ?? and ?? vs. Tc^A curves give information about the effects of Mn and Al substitutions on the different scattering channels (interband and intraband, magnetic or non-magnetic). It turns out that the main effect of Mn is to increase the spin-flip scattering within the ? band (with smaller contributions from either the ?-? or the ?-? channels), as also confirmed by first-principle bandstructure calculations. In the case of Al, the band-filling effect is largely dominant. An increase in non-magnetic interband scattering is possible, but small enough not to give rise to gap merging. In collaboration with G.A. Ummarino, A. Calzolari, M. Tortello, D. Delaude, R.S. Gonnelli, Dipartimento di Fisica and CNISM, Politecnico di Torino, Italy; V.A. Stepanov, P.N. Lebedev Physical Institute, RAS, Moscow, Russia; N.D. Zhigadlo, J. Karpinski, Laboratory for Solid State Physics, ETHZ, Zurich, Switzerland; and S. Massidda, Dipartimento di Fisica, Universitàdi Cagliari, Italy.

Daghero, D.

2007-03-01

476

Spatial and Geochemical Techniques to Improve Exposure Assessment of Manganese in Windsor, Ontario  

NASA Astrophysics Data System (ADS)

This study was conducted to investigate the urban geochemistry of the city of Windsor (Ontario) and to provide added source apportionment information to work being carried out by the Canadian government. The goal of this study was to investigate the distribution, spatial variation and sources of manganese in urban Windsor soil. The literature indicates that human exposure to high levels of manganese, via inhalation, can cause respiratory and/or neurological effects. At the outset of the present study it was first hypothe