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1

Development of High-Manganese Steels.  

National Technical Information Service (NTIS)

Nonmagnetic properties, high toughness and low cost are the principal characteristics of high-manganese austenitic steels. Taking advantage of these characteristics, three different types of high-manganese austenitic steels suited for different applicatio...

H. Masumoto H. Yoshimura T. Akasawa S. Ohba T. Harada

1983-01-01

2

Weldability of austenitic manganese steel  

Microsoft Academic Search

Hadfield’s manganese steel, nominally Fe–1.2%C–13%Mn, is an alloy of inherent toughness, work-hardening characteristics and excellent resistance to some types of adhesive and abrasive wear. However, due to its low yield strength, it may be deformed markedly before its work-hardening become effective. In certain applications, such as railroad crossings and rock-crushers, this can be a disadvantage. In practice, when this deformation

J. Mendez; M. Ghoreshy; W. B. F. Mackay; T. J. N. Smith; R. W. Smith

2004-01-01

3

Flash butt welding of high manganese steel crossing and carbon steel rail  

Microsoft Academic Search

This study sets out to introduce the flash butt welding of high manganese steel crossing and carbon steel rail by employing an austenite–ferrite two-phase stainless steel insert. There are two flash butt welded joints for the connection of the high manganese steel and the carbon steel rail, one is the welded joint of the carbon steel and the stainless steel,

Fucheng Zhang; Bo Lv; Baitao Hu; Yanguo Li

2007-01-01

4

The Fracture Behavior of Quenched and Tempered Manganese Steels  

Microsoft Academic Search

Manganese is present in all commercial low alloy steels, but its various effects on fracture are not completely understood. In this paper we report a study of the fracture behavior of quenched and tempered manganese steels. The steels were austenitized, quenched, and then tempered at temperatures between 150 °C and 500 °C. If the steel contained phosphorous, the fracture energy

C. L. Briant; S. K. Banerji

1982-01-01

5

The Fracture Behavior of Quenched and Tempered Manganese Steels  

Microsoft Academic Search

Manganese is present in all commercial low alloy steels, but its various effects on fracture are not completely understood.\\u000a In this paper we report a study of the fracture behavior of quenched and tempered manganese steels. The steels were austenitized,\\u000a quenched, and then tempered at temperatures between 150 ?C and 500 ?C. If the steel contained phosphorous, the fracture energy

C. L. Briant; S. K. Banerji

1982-01-01

6

Wear resistance of high-manganese steels with different structures  

Microsoft Academic Search

1.An increase of the manganese and carbon concentrations of high-manganese austenitic steels increases the resistance to abrasive wear.2.The decomposition of austenite during tempering reduces the wear resistance despite the increase in hardness.3.The difference in the abrasive wear resistance of high-manganese steels with different structures is due to the degree of hardening of the friction surface during wear.4.An increase of the

A. G. Shchulepnikova

1968-01-01

7

Characterization of non-magnetic Mn-Cr steel as a low induced activation material for vacuum vessels  

NASA Astrophysics Data System (ADS)

The JT-60SU (Super Upgrade) program is under discussion at Japan Atomic Energy Research Institute (JAERI). Its design optimization activity requires the vacuum vessel material to be non-magnetic, very strong and with low induced activation. However, there is no suitable material available to fulfill all the requirements. JAERI started to develop a new material for the vacuum vessel together with the Japan Steel Works (JSW). Chemical composition and metallurgical processes were optimized and a new steel named VC9, which has the composition of Cr - 16 wt%, Mn - 15.5 wt%, C - 0.2 wt%, and N - 0.2 wt% with non-magnetic single ? phase, was selected as a candidate material. Here, mechanical properties and weldability of VC9 were examined and the results were compared with those of type 316 or 316L stainless steel. It was shown that VC9 has good mechanical properties and weldability.

Saito, S.; Fukaya, K.; Ishiyama, S.; Eto, M.; Sato, I.; Kusuhashi, M.; Hatakeyama, T.; Takahashi, H.; Kikuchi, M.

2000-12-01

8

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

PubMed

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

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

2009-09-30

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

The Fracture Behavior of Quenched and Tempered Manganese Steels  

NASA Astrophysics Data System (ADS)

Manganese is present in all commercial low alloy steels, but its various effects on fracture are not completely understood. In this paper we report a study of the fracture behavior of quenched and tempered manganese steels. The steels were austenitized, quenched, and then tempered at temperatures between 150 °C and 500 °C. If the steel contained phosphorous, the fracture energy after all tempering treatments was very low and the fracture was intergranular. Tempering at temperatures near 350 °C produced especially low fracture energies because of the occurrence of intergranular tempered martensite embrittlement. Manganese does not increase the amount of phosphorous segregation during austenitization or tempering. However, it may increase the embrittling potency of phosphorous. If the steel did not contain a sufficient concentration of a grain boundary embrittling element such as phosphorous, the fracture mode was ductile microvoid coalescence. In this case manganese can be very important because it scavenges all of the residual sulfur in the alloy to form MnS precipitates. These are the initial sites of microvoid formation during ductile fracture, and their presence, especially in the form of elongated stringers, can lead to a reduced fracture energy.

Briant, C. L.; Banerji, S. K.

1982-05-01

11

Critical Aspects of Alloying of Sintered Steels with Manganese  

NASA Astrophysics Data System (ADS)

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

Hryha, Eduard; Dudrova, Eva; Nyborg, Lars

2010-11-01

12

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

13

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

14

Mechanical properties and strain-induced phase transformations of some high-strength manganese steels  

Microsoft Academic Search

Work has been carried out to determine the influence of composition and heat treatment on the mechanical properties of some\\u000a high-strength manganese steels. These steels display impressive mechanical properties in the as-hot-rolled and solution-treated\\u000a conditions. These impressive mechanical properties have been directly related to the strain-induced phase transformation which\\u000a was monitored continuously using a magnetic reluctance techniquein situ and dynamically

A. O. Inegbenebor; R. D. Jones; Brian Ralph

1989-01-01

15

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

Microsoft Academic Search

The causes of embrittlement in several plain carbon-manganese and niobium-treated steels between 800 and 1200 °C have been investigated. Tensile ductility was measured as a function of temperature and strain rate. Percent elongation and reduction in area were used to characterize the temperature dependence and severity of the ductility loss. The size, distribution, and composition of grain boundary precipitates were

W. T. Nachtrab; Y. T. Chou

1986-01-01

16

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

17

Effect of Different Casting Parameters on the Cleanliness of High Manganese Steel Ingots Compared to High Carbon Steel  

NASA Astrophysics Data System (ADS)

The increasing demand for excellent steel properties has led to the creation of new steel grades such as high manganese TWIP and TRIP steels which are scientifically examined in Germany within the international research framework of the SFB 761 "Steel-ab initio." The production of these high-technology products, utilizing mainly the ingot-casting method, leads to new challenges in the prevention of cast defects. At RWTH Aachen University, a systematic investigation of the solidification process as it relates to shrinkage cavity, macrosegregation, cleanliness, and surface imperfections in as-cast ingots is being conducted. A particular attention was devoted to the effects of such casting parameters as superheat, pouring rate, hot top, and stirring conditions on the solidification and cleanliness of low carbon alloyed and high manganese alloyed steels. The experimental results show that rising manganese content leads to a higher amount and larger size of inclusions while rising carbon content enhances the inclusion generation in the same way. It was found that a bottom teeming system combined with an inert gas atmosphere produces the best quality and that if casting is performed with a runner-system, it is important to use a SiO2-free refractory to avoid oxidizing the Mn content of the melt to MnO inclusions by redox-reactions.

von Schweinichen, Petrico; Chen, Zhiye; Senk, Dieter; Lob, Alexander

2013-12-01

18

Manganese  

MedlinePLUS

... the body, including processing of cholesterol, carbohydrates, and protein. It might also be involved in bone formation. ... Antibiotics (Quinolone antibiotics)Manganese might decrease how much ... antibiotics might decrease the effectiveness of some antibiotics. To avoid ...

19

Medium-Alloy Manganese-Rich Transformation-Induced Plasticity Steels  

NASA Astrophysics Data System (ADS)

The manganese concentration of steels which rely on transformation-induced plasticity is generally less than 2 wt pct. Recent work has highlighted the potential for strong and ductile alloys containing some 6 wt pct of manganese, but with aluminum additions in order to permit heat treatments which are amenable to rapid production. However, large concentrations of aluminum also cause difficulties during continuous casting. Alloy design calculations have been carried out in an effort to balance these conflicting requirements, while maintaining the amount of retained austenite and transformation kinetics. The results indicate that it is possible by adjusting the carbon and manganese concentrations to reduce the aluminum concentration, without compromising the mechanical properties or transformation kinetics. The deformation-induced transformation of retained austenite is explained quantitatively, for a range of alloys, in terms of a driving force which takes into account the very fine state of the retained austenite.

Suh, Dong Woo; Ryu, Joo Hyun; Joo, Min Sung; Yang, Hong Seok; Lee, Kyooyoung; Bhadeshia, H. K. D. H.

2013-01-01

20

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

21

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

22

Thermal Growth and Performance of Manganese Cobaltite Spinel Protection Layers on Ferritic Stainless Steel SOFC Interconnects  

Microsoft Academic Search

To protect solid oxide fuel cells (SOFCs) from chromium poisoning and improve metallic interconnect stability, manganese cobaltite spinel protection layers with a nominal composition of Mn1.5Co1.5O4 were thermally grown on Crofer22 APU, a ferritic stainless steel. Thermal, electrical and electrochemical investigations indicated that the spinel protection layers not only significantly decreased the contact area specific resistance (ASR) between a LSF

Zhenguo Yang; Guanguang Xia; Steven P. Simner; Jeffry W. Stevenson

2005-01-01

23

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

Microsoft Academic Search

Ultrasonic nondestructive examination (NDE) has a long and successful history of application across a wide array of industries, including nuclear, aerospace, and transportation sectors. In coarse-grained, cast Manganese (Mn) steel frog components, NDE\\/inspection challenges are encountered both in-field (after the frogs have been installed on a rail line) and at the manufacturing facilities during post-fabrication QA\\/QC activities. Periodically inherently flawed

A. Cinson; A. Diaz; M. Prowant

2011-01-01

24

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

Microsoft Academic Search

The causes of embrittlement in several plain carbon-manganese and niobium-treated steels between 800 and 1200 °C have been\\u000a investigated. Tensile ductility was measured as a function of temperature and strain rate. Percent elongation and reduction\\u000a in area were used to characterize the temperature dependence and severity of the ductility loss. The size, distribution, and\\u000a composition of grain boundary precipitates were

W. T. Nachtrab; Y. T. Chou

1986-01-01

25

Sintered manganese steels produced using copper-bearing ferromanganese master alloy  

Microsoft Academic Search

The paper examines the properties of sintered manganese steels produced with the use of copper-bearing ferromanganese master\\u000a alloys depending on the master alloy content and sintering temperature. It is shown that increase in the master alloy content\\u000a promotes higher strength and hardness. The interaction of master alloy particles with the matrix material is accompanied by\\u000a much more uniform distribution of

G. A. Baglyuk; L. A. Sosnovskii; V. I. Vol’fman; A. I. Khomenko

2011-01-01

26

STUDY OF THE EMBRITTLEMENT OF MANGANESE-MOLYBDENUM WELDABLE STEELS DURING STRESS-RELIEF ANNEALING AFTER WELDING  

Microsoft Academic Search

A shift in the curves for the change in toughness was observed for three ; typical steels after being held for 1 to 100 hours at temperatures from 400 to ; 700 deg C and after cycling corresponding to stress-relief anneals at 625 deg C. ; A comparison is made with carbon- manganese steels. Embrittlement increases with ; the temperature

P. F. Martin; C. Roques; P. Bastien

1962-01-01

27

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

28

Wear resistance of high-manganese steel castings  

Microsoft Academic Search

Conclusions 1.To improve the wear resistance of parts made of G13-L steel, the latter has to be paired at as low a temperature as possible.2.Castings (drag buckets, crusher cones and front ladle walls) should not contain more than 0.06–0.07% P and 0.5%–0.6% Si.3.The castings must be inspected for microstructure and impact toughness.

M. A. Guzovskaya; Ya. D. Khorin

1962-01-01

29

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

30

Effect of Mass on the Mechanical Properties of Quenched and Tempered 1.5 Per Cent Manganese Steel and '8620' Alloy Steel.  

National Technical Information Service (NTIS)

The report gives the results of tests to determine the effect of mass on the response to quenching and tempering of 1.5 per cent manganese steel and '8620' low-alloy steel, both of which are commonly used for haulage and cage-suspension purposes. It was s...

J. H. Foley D. W. Wilson

1970-01-01

31

Influence of alloy elements on the properties of manganese steels in the 293–4°K temperature range  

Microsoft Academic Search

1.With an increase in manganese and carbon contents in austenitic Fe-C-Mn steels their mechanical properties at temperatures of 293 to 4°K increase and the magnetic permeability decreases.2.Alloying of Fe-C-Mn steels with chromium leads to a significant reduction in their magnetic permeability, but sharp embrittlement at cryogenic temperatures occurs.3.Aluminum has a favorable influence on the mechanical properties of Fe-C-Mn steels but

B. S. Ermakov; V. G. Khoroshailov

1985-01-01

32

On the strain hardening and texture evolution in high manganese steels: Experiments and numerical investigation  

NASA Astrophysics Data System (ADS)

We present a systematic investigation on the strain hardening and texture evolution in high manganese steels where twinning induced plasticity (TWIP) plays a significant role for the materials' plastic deformation. Motivated by the stress-strain behavior of typical TWIP steels with compositions of Fe, Mn, and C, we develop a mechanistic model to explain the strain-hardening in crystals where deformation twinning dominates the plastic deformation. The classical single crystal plasticity model accounting for both dislocation slip and deformation twinning are then employed to simulate the plastic deformation in polycrystalline TWIP steels. While only deformation twinning is activated for plasticity, the simulations with samples composed of voronoi grains cannot fully capture the texture evolution of the TWIP steel. By including both twinning deformation and dislocation slip, the model is able to capture both the stress-strain behaviors and the texture evolution in Fe-Mn-C TWIP steel in different boundary-value problems. Further analysis on the strain contributions by both mechanisms suggests that deformation twinning plays the dominant role at the initial stage of plasticity in TWIP steels, and dislocation slip becomes increasingly important at large strains.

Li, Yongqiang; Zhu, Lianchun; Liu, Yao; Wei, Yujie; Wu, Yanxin; Tang, Di; Mi, Zhenli

2013-12-01

33

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

34

Thermal Growth and Performance of Manganese Cobaltite Spinel Protection Layers on Ferritic Stainless Steel SOFC Interconnects  

SciTech Connect

To protect solid oxide fuel cells (SOFCs) from chromium poisoning and improve metallic interconnect stability, manganese cobaltite spinel protection layers with a nominal composition of Mn1.5Co1.5O4 were thermally grown on Crofer22 APU, a ferritic stainless steel. Thermal, electrical and electrochemical investigations indicated that the spinel protection layers not only significantly decreased the contact area specific resistance (ASR) between a LSF cathode and the stainless steel interconnect, but also inhibited the sub-scale growth on the stainless steel by acting as a barrier to the inward diffusion of oxygen. A long-term thermal cycling test demonstrated excellent structural and thermomechanical stability of these spinel protection layers, which also acted as a barrier to outward chromium cation diffusion to the interconnect surface. The reduction in the contact ASR and prevention of Cr migration achieved by application of the spinel protection layers on ferritic stainless steel resulted in improved stability and electrochemical performance of SOFCs.

Yang, Zhenguo; Xia, Guanguang; Simner, Steven P.; Stevenson, Jeffry W.

2005-08-01

35

Cryogenic S-N Fatigue and Fatigue Crack Propagation Behaviors of High Manganese Austenitic Steels  

NASA Astrophysics Data System (ADS)

In the current study, the S-N fatigue and the fatigue crack propagation (FCP) behaviors of high manganese austenitic steels, including Fe24Mn and Fe22Mn, were studied, and the results were compared with STS304 (Fe-1Si-2Mn-20Cr-10Ni). The S-N fatigue tests were conducted at 298 K and 110 K (25 °C and -163 °C), respectively, and at an R ratio of 0.1 under a uniaxial loading condition. The FCP tests were conducted at 298 K and 110 K (25 °C and -163°C), respectively, and at R ratios of 0.1 and 0.5, respectively, using compact tension specimens. The resistance to S-N fatigue of each specimen increased greatly with decreasing temperature from 298 K to 110 K (25 °C to -163 °C) and showed a strong dependency on the flow stress. The FCP behaviors of the austenitic steels currently studied substantially varied depending on testing temperature, applied ? K (stress intensity factor range), and R ratio. The enhanced FCP resistance was observed for the Fe24Mn and the Fe22Mn specimens particularly in the near-threshold ? K regime, while the enhancement was significant over the entire ? K regimes for the STS304 specimen, with decreasing temperature from 298 K to 110 K (25 °C to -163 °C). The S-N fatigue and the FCP behaviors of high manganese austenitic steels are compared with STS304 and discussed based on the fractographic and the micrographic observations.

Jeong, Dae-Ho; Lee, Soon-Gi; Jang, Woo-Kil; Choi, Jong-Kyo; Kim, Young-Ju; Kim, Sangshik

2013-10-01

36

Mild steels coated with 14% manganese covered electrodes (E7UM200-K and E1UM350): Phenomena at the steel-coating interface  

Microsoft Academic Search

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,

F.. Molleda; J. Mora; E. Carrillo; E. Mora; B. G. Mellor

2006-01-01

37

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

NASA Astrophysics Data System (ADS)

This investigation focuses on the austenite formation process during continuous heating, over a wide range of heating rates (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 Al). High resolution dilatometry, combined with metallographic observations, was used to determine the starting ( Ac 1) and finishing ( Ac 3) temperatures of this transformation. It is shown that both the aluminum content and the applied heating rate have a strong influence on this process. During fast heating (>1 K/s), the pearlite phase present in the initial microstructure remains almost unaffected up to temperature Ac 1. On the contrary, during slow heating, cementite lamellas inside pearlite partially dissolve, this dissolution effect being more pronounced for the lower carbon and higher aluminum content steels. The changes in the initial microstructure during slow heating affect the austenite nucleation and growth processes. Furthermore, in the aluminum alloyed steels, slow heating conditions shift the Ac 3 temperature to higher values. This shift is suggested to be due to aluminum partitioning from austenite to ferrite, which stabilizes ferrite and delays its transformation to higher temperatures. Thermodynamic calculations carried out with MTDATA software seem to support some of the experimental observations carried out under very low heating conditions close to equilibrium (0.05 K/s).

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

2011-09-01

38

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

39

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

NASA Astrophysics Data System (ADS)

The behavior of manganese and titanium sulfides during the hot deformation of a low-carbon, low-manganese, titanium-added steel has been studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS) analysis. In addition, the effects of deformation temperature and strain rate on the size and distribution of precipitates have been studied using an automatic inclusion analysis system. Also, the effect of precipitate distribution on mechanical properties was studied at different deformation conditions of temperature and strain rate. The TEM and SEM analyses revealed the presence of a wide variety of simple and/or complex precipitates in the as-cast structure. These precipitates behaved differently during the hot deformation of steel. Precipitates deformed less at higher deformation temperatures, whereas an increase in strain rate increased the elongation of precipitates.

Dehghan-Manshadi, Ali; Dippenaar, Rian J.

2010-12-01

40

Influence of carbon, nickel, manganese, and vanadium on stress-corrosion cracking of steels in a medium containing hydrogen sulfide  

Microsoft Academic Search

conditions. We investigated the influence of carbon (0.03-0.45%), nickel (0.5-20%), manganese (1.0-16%), and vanadium (0.1-3.0%) on stress-corrosion cracking of steels in a 0.5% acetic acid solution saturated with hydrogen sulfide. In investigating the role of carbon, we remelted previously carburZzed carbonyl iron in a type SShVL vacuum furnace and cast it into primary ingots. The required quantity of carbon in

L. M. Karvatskii; R. I. Koval'chuk

1979-01-01

41

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

Microsoft Academic Search

1.When 8% of Mn is introduced into a high-chromium cast iron of hypereutectic composition, the austenite becomes the predominant phase of the carbide eutectic; this contributes to increased strength properties of the alloys with an insignificant reduction in their wear resistance.2.During the electric-slag facing of a high-chromium cast iron containing 8% of Mn on high-manganese steel 110G13L diffusion equalization of

V. P. Ponomarenko; A. Ya. Shvartser; G. V. Stroganova

1985-01-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

43

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

NASA Astrophysics Data System (ADS)

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

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

1986-11-01

44

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

45

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

46

Nanocharacterisation of precipitates in austenite high manganese steels with advanced techniques: HRSTEM and DualEELS mapping  

NASA Astrophysics Data System (ADS)

To achieve optimal mechanical properties in high manganese steels, the precipitation of nanoprecipitates of vanadium and niobium carbides is under investigation. It is shown that under controlled heat treatments between 850°C and 950°C following hot deformation, few-nanometre precipitates of either carbide can be produced in test steels with suitable contents of vanadium or niobium. The structure and chemistry of these precipitates are examined in detail with a spatial resolution down to better than 1 nm using a newly commissioned scanning transmission electron microscope. In particular, it is shown that the nucleation of vanadium carbide precipitates often occurs at pre-existing titanium carbide precipitates which formed from titanium impurities in the bulk steel. This work will also highlight the links between the nanocharacterisation and changes in the bulk properties on annealing.

Bobynko, J.; Craven, A. J.; McGrouther, D.; MacLaren, I.; Paul, G.

2014-06-01

47

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

SciTech Connect

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 {alpha} {yields} {gamma} transformation has been found in this steel by means of dilatometric analysis. Moreover, the temperature range of pearlite dissolution process has been determined allowing to select the most suitable intercritical temperature to obtain dual phase microstructures with optimum combination of mechanical properties. The influence of the pearlite morphology on dissolution process has been also studied in this work.

Garcia de Andres, C.; Caballero, F.G.; Capdevila, C. [Consejo Superior de Investigaceiones Cientificas, Madrid (Spain)] [Consejo Superior de Investigaceiones Cientificas, Madrid (Spain)

1998-05-12

48

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.

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

2011-01-01

49

Investigation of the Delayed Fracture Phenomenon in Deep-Drawn Austenitic Manganese-Based Twinning-Induced Plasticity Steels  

NASA Astrophysics Data System (ADS)

The phenomenon of delayed fracture in three austenitic manganese-based Twinning-Induced Plasticity steels is investigated by means of video observation and magnetic measurements. Delayed fracture is observed in the direction perpendicular to the rolling direction, in coincidence with the highest ?'-martensite fraction in a deep-drawn cup. The formation of a small fraction of ?'-martensite, irrespective of the chemical composition examined, is indicative of the formation of crack initiation sites. We propose an intermittent crack propagation concept and model for the phenomenon of delayed fracture.

van Tol, R. T.; Zhao, L.; Bracke, L.; Kömmelt, P.; Sietsma, J.

2013-10-01

50

Effect of manganese on annealing texture, plastic anisotropy, and mechanical properties of low-carbon steels containing 0.067 Pct phosphorus  

Microsoft Academic Search

To establish the range of manganese content in phosphorus-containing low-carbon steels that will provide superiorr\\u000a m andAr values in cold-rolled sheets, the effects of manganese on annealing texture, plastic anisotropy, and mechanical properties\\u000a of steels containing 0.067 pct P were studied. Both vacuum and air-melted laboratory heats were investigated. Results show\\u000a that highr\\u000a m and low Ar values, a desirable

Hsun Hu

1977-01-01

51

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

PubMed

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

Keane, Michael; Stone, Samuel; Chen, Bean

2010-05-01

52

Investigation on Pitting Corrosion of Nickel-Free and Manganese-Alloyed High-Nitrogen Stainless Steels  

NASA Astrophysics Data System (ADS)

Pitting corrosion behavior of three kinds of nickel-free and manganese-alloyed high-nitrogen (N) stainless steels (HNSSs) was investigated using electrochemical and immersion testing methods. Type 316L stainless steel (316L SS) was also included for comparison purpose. Both solution-annealed and sensitization-treated steels were examined. The solution-annealed HNSSs showed much better resistance to pitting corrosion than the 316L SS in both neutral and acidic sodium chloride solutions. The addition of molybdenum (Mo) had no further improvement on the pitting corrosion resistance of the solution-annealed HNSSs. The sensitization treatment resulted in significant degradation of the pitting corrosion resistance of the HNSSs, but not for the 316L SS. Typical large size of corrosion pits was observed on the surface of solution-annealed 316L SS, while small and dispersed corrosion pits on the surfaces of solution-annealed HNSSs. The sensitization-treated HNSSs suffered very severe pitting corrosion, accompanying the intergranular attack. The addition of Mo significantly improved the resistance of the sensitization-treated HNSSs to pitting corrosion, particularly in acidic solution. The good resistance of the solution-annealed HNSSs to pitting corrosion could be attributed to the passive film contributed by N, Cr, and Mo. The sensitization treatment degraded the passive film by decreasing anti-corrosion elements and Cr-bearing oxides in the passive film.

Wu, Xinqiang; Fu, Yao; Huang, Junbo; Han, Enhou; Ke, Wei; Yang, Ke; Jiang, Zhouhua

2009-04-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

54

CEMS study of strain induced phase transformation in manganese Hadfield steel  

Microsoft Academic Search

A Conversion Electron Mössbauer Spectroscopy, (CEMS), study of phase transformations in a Hadfield steel induced by high rate strains is reported. Hadfield steel samples were impact deformed and the ensuing changes in the magnetic properties at the deformed zone and its surroundings have been studied by CEMS. The CEMS results are compared with wear tests and optical microscopy and show

E. D. Cabanillas; E. P. Alvarez; A. Hey; R. C. Mercader

1991-01-01

55

Levels of arsenic, cadmium, lead, manganese and zinc in biological samples of paralysed steel mill workers with related to controls.  

PubMed

The determination of essential trace and toxic elements in the biological samples of human beings is an important clinical 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 of arsenic, cadmium, lead, manganese and zinc were determined in biological samples (blood, urine and scalp hair samples) of exposed paralysis and non-paralysed steel mill workers. For comparative purposes, unexposed healthy subjects of same age group were selected as referents. The elements in the biological samples were measured by atomic absorption spectrophotometry prior to microwave-assisted acid digestion. The validity of the methodology was checked by the biological certified reference materials. The results indicate that the level understudy elements in all three biological samples were significantly higher in paralysed workers of both groups (quality control and production) as compared to referents (p?

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

2011-12-01

56

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

57

CEMS study of strain induced phase transformation in manganese Hadfield steel  

Microsoft Academic Search

A Conversion Electron Mssbauer Spectroscopy, (CEMS), study of phase transformations in a Hadfield steel induced by high rate\\u000a strains is reported. Hadfield steel samples were impact deformed and the ensuing changes in the magnetic properties at the\\u000a deformed zone and its surroundings have been studied by CEMS. The CEMS results are compared with wear tests and optical microscopy\\u000a and show

E. D. Cabanillas; E. P. Alvarez; A. Hey; R. C. Mercader

1991-01-01

58

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.

59

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

60

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

61

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

Microsoft Academic Search

Neural network modelling suggested that the impact strength of high-strength steel weld metals could be increased at moderate expense to yield strength once Ni additions are made in a controlled manner with respect to Mn. Based on these predictions, shielded metal arc welding was used to prepare weld metals with Ni at 7 and 9 wt. % while Mn was

E. Keehan; H. O. Andrén; L. Karlsson; M. Murugananth; H. K. D. H. Bhadeshia

62

Evaluation of arsenic, cobalt, copper and manganese in biological Samples of Steel mill workers by electrothermal atomic absorption Spectrometry.  

PubMed

The determination of trace and toxic elements in biological samples (blood, urine and scalp hair samples) of human beings is an important clinical test. The aim of our present study was to determine the concentration of arsenic (As), copper (Cu), cobalt (Co) and manganese (Mn), in biological samples of male production workers (PW) and quality control workers (QW) of steel mill, with aged 25-55 years, to assess the possible influence of environmental exposure. For comparison purpose, the same biological samples of unexposed healthy males of same age group were collected as control subjects. The determination of all elements in biological samples was carried out by electrothermal atomic absorption spectrometry, prior to microwave assisted acid digestion. The accuracy of the As, Cu, Co and Mn measurements was tested by simultaneously analyzing certified reference materials (CRMs) and for comparative purposes conventional wet acid digestion method was used on the same CRMs. No significant differences were observed between the analytical results and the certified values, using both methods (paired t-test at P > 0.05). The results indicate that concentrations of As, Cu, Co and Mn in all three biological samples of the exposed workers (QW and PW) were significantly higher than those of the controls. The possible correlation of these elements with the etiology of different physiological disorders is discussed. The results were also demonstrated the need of attention for improvements in workplace, ventilation and industrial hygiene practices. PMID:19318505

Afridi, H I; Kazi, T G; Kazi, N G; Jamali, M K; Arain, M B; Sirajuddin; Kandhro, G A; Shah, A Q; Baig, J A

2009-02-01

63

Tensile deformation behavior of high manganese austenitic steel: The role of grain size  

Microsoft Academic Search

The tensile deformation behavior and microstructural evolutions of twinning induced plasticity (TWIP) steel with the chemical composition of Fe–31Mn–3Al–3Si and average grain sizes in the range of 2.1–72.6?m have been analyzed. For each grain size, the Hollomon analysis and also the Crussard–Jaoul (C–J) analysis as an alternative method to describe the work hardening behavior were investigated. The results indicated that

G. Dini; A. Najafizadeh; R. Ueji; S. M. Monir-Vaghefi

2010-01-01

64

Tensile, Fracture, and Fatigue Crack Growth Rate Behavior of High Manganese Steels  

NASA Astrophysics Data System (ADS)

Mechanical low temperature investigations were carried out to determine the cryogenic mechanical properties of newly developed Fe-Cr-Mn alloys with contents of chromium between 5 % and 10 % and manganese between 30 % and 40 % under the Project G-811, Russia. The final products were forged, rolled, and solution heat treated to obtain appropriate plate sizes necessary for the mechanical measurements. The tensile properties of these alloys determined between 4 K and 7 K show for certain alloy combination high elongation values at fracture of greater than 50 % with considerable high yield strengths around 900 MPa. The measured fracture toughness values with small scale compact tension specimens using elastic plastic J-tests show KIC data between 100 MPa?m and 220 MPa?m according to the alloy combination. Fatigue crack growth rate (FCGR) measurements of these alloys result also in some alloy combination case, high resistance against crack propagation with measured Paris coefficients of m ~ 5 and C ~ 8.5 E-13 mm/cycle. Thermal expansion of these alloys has been also determined resulting in values between 1600 ?m/m and 1700 ?m/m expansion from 5 K to 290 K.

Nyilas, A.; Weiss, K.; Grikurov, G.; Zoidze, N.

2006-03-01

65

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

66

Manganese recycling in the United States in 1998  

USGS Publications Warehouse

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

Jones, Thomas S.

2001-01-01

67

Investigation of the Effect of Tungsten Substitution on Microstructure and Abrasive Wear Performance of In Situ VC-Reinforced High-Manganese Austenitic Steel Matrix Composite  

NASA Astrophysics Data System (ADS)

Particulate VC-reinforced high-manganese austenitic steel matrix composites with different vanadium and tungsten contents were synthesized by conventional alloying and casting route. Microstructural characterizations showed that the composites processed by in situ precipitation of the reinforcements were composed of V8C7 particulates distributed in an austenitic matrix. It was observed that addition of tungsten to austenite increases work-hardening rate of subsurface layer during pin-on disk wear test. The maximum abrasive wear resistance was achieved at tungsten content equal to 2 wt pct. However, excessive addition of tungsten promoted the formation of W3C phase and reduced the abrasive wear resistance because of decrease in distribution homogeneity and volume fraction of the reinforcing VC particles.

Moghaddam, Emad Galin; Karimzadeh, Neda; Varahram, Naser; Davami, Parviz

2013-08-01

68

Applications of an Ultra-Low Carbon Stainless Steel of the Type 18 Chromium-8.5 Nickel-3 Manganese.  

National Technical Information Service (NTIS)

Stainless steels of type 18-8 have developed into commercial products, such as: AISI (U.S.A. system) 302, 303, 304L, 321 etc. Some of them contain approx 0.10%C, other less. The steel is not clean because of the existence of the intermetallic compounds of...

J. Zhang J. Zhao

1993-01-01

69

On the Effect of Manganese on Grain Size Stability and Hardenability in Ultrafine-Grained Ferrite/Martensite Dual-Phase Steels  

NASA Astrophysics Data System (ADS)

Two plain carbon steels with varying manganese content (0.87 wt pct and 1.63 wt pct) were refined to approximately 1 ?m by large strain warm deformation and subsequently subjected to intercritical annealing to produce an ultrafine grained ferrite/martensite dual-phase steel. The influence of the Mn content on microstructure evolution is studied by scanning electron microscopy (SEM). The Mn distribution in ferrite and martensite is analyzed by high-resolution electron backscatter diffraction (EBSD) combined with energy dispersive X-ray spectroscopy (EDX). The experimental findings are supported by the calculated phase diagrams, equilibrium phase compositions, and the estimated diffusion distances using Thermo-Calc (Thermo-Calc Software, McMurray, PA) and Dictra (Thermo-Calc Software). Mn substantially enhances the grain size stability during intercritical annealing and the ability of austenite to undergo martensitic phase transformation. The first observation is explained in terms of the alteration of the phase transformation temperatures and the grain boundary mobility, while the second is a result of the Mn enrichment in cementite during large strain warm deformation, which is inherited by the newly formed austenite and increases its hardenability. The latter is the main reason why the ultrafine-grained material exhibits a hardenability that is comparable with the hardenability of the coarse-grained reference material.

Calcagnotto, Marion; Ponge, Dirk; Raabe, Dierk

2012-01-01

70

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

71

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

Microsoft Academic Search

The authors investigate extending the service lives of components by the method of electric-slag facing of working surfaces. Steel 45 was used in the annealed state. Electric-slag remelting was the method used to determine the bending strength. Metallographic examinations were conducted under an MIM-8m microscope, while x-ray analysis of the built-up and base metals were performed on a DRON-2 diffractometer.

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

1986-01-01

72

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

NASA Astrophysics Data System (ADS)

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

Mosecker, Linda; Saeed-Akbari, Alireza

2013-06-01

73

49 CFR Appendix A to Part 178 - Specifications for Steel  

Code of Federal Regulations, 2010 CFR

...the maximum limit for manganese on ladle analysis may...Rephosphorized Grade 3 steels containing no more...exceed 0.15 percent and manganese does not exceed 1 percent...Tolerances [A heat of steel made under any...

2009-10-01

74

49 CFR Appendix A to Part 178 - Specifications for Steel  

Code of Federal Regulations, 2010 CFR

...the maximum limit for manganese on ladle analysis may...Rephosphorized Grade 3 steels containing no more...exceed 0.15 percent and manganese does not exceed 1 percent...Tolerances [A heat of steel made under any...

2010-10-01

75

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

PubMed

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

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

2003-03-01

76

Manganese encephalopathy: utility of early magnetic resonance imaging  

Microsoft Academic Search

The use of magnetic resonance imaging (MRI) provides visual evidence of cerebral deposits of paramagnetic metals. The usefulness of MRI is described in connection with the manganese poisoning of a 44 year old arc welder who had been engaged in the repair and recycling of railroad track made of manganese steel alloy.

K Nelson; J Golnick; T Korn; C Angle

1993-01-01

77

Manganese consumption and recycling flow model. Information circular/1995  

SciTech Connect

The report follows the flow of manganese through its metallurgical and chemical applications and highlights areas where significant losses occur owing to downgrading, export, or disposal. The study indicates that materials containing 695,000 short tons (st) of manganese were consumed domestically in 1990. Scrap recovery specifically for manganese recycling was insignificant. However, considerable manganese was recycled through processing operations as a minor component of ferrous and nonferrous scrap and steel slag. The major loss category is manganese lost in steel processing, 323,156 st or 46 pct of the 1990 apparent consumption. Most of this loss reports to steelmaking slags. Recovery from slags is technically feasible, but is not economically feasible.

Gabler, R.C.

1995-04-01

78

Deformation-induced dissolution of carbides of the Me(V, Mo)-C Type in high-manganese steels upon the friction effect  

NASA Astrophysics Data System (ADS)

By the method of Mössbauer spectroscopy, it is shown that the aging at 923 K (for ten hours) of quenched stable austenite steels, FeC0.8Mn20V2Mo2 and FeC0.8Mn2V2, which leads to a depletion of austenite in carbon, causes the enhancement of steel magnetism owing to the development of antiferromagnetic ordering in these steels. A severe plastic deformation under conditions of dry sliding friction reduces the Néel temperature and the mean effective magnetic field of aged steels because of the deformation-induced dissolution of Me-C carbides and the transition of part of carbon atoms to a ? solid solution. The deformation-induced dissolution of the carbide phase proceeds most vigorously in the FeC0.8Mn2V2 steel, which is characterized by the minimum size of carbide particles. It is concluded that the deformation-induced dissolution of the carbide phase is a factor that has a substantial positive effect on the wear resistance of austenite steels dispersion-hardened by aging.

Shabashov, V. A.; Korshunov, L. G.; Zamatovskii, A. E.; Litvinov, A. V.; Sagaradze, V. V.; Kositsyna, I. I.

2012-09-01

79

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.

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

2011-01-01

80

Electrochemistry of passive metals modified by manganese oxides deposited by Leptothrix discophora : two-step model verified by ToF-SIMS  

Microsoft Academic Search

We have applied time-of-flight secondary ion mass spectroscopy (ToF-SIMS) to study microbially induced ennoblement of 316L stainless steel and Ti–6Al–4V surfaces exposed to manganese-oxidizing bacteria Leptothrix discophora SP-6. Our observations indicate that manganese biomineralization occurs in two steps: first, the divalent manganese (Mn2+) is oxidized to manganese oxyhydroxide, MnOOH; then the MnOOH is further oxidized to manganese dioxide, MnO2. Both

Xianming Shi; Recep Avci; Zbigniew Lewandowski

2002-01-01

81

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

Microsoft Academic Search

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

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

2011-01-01

82

Influence of Nickel and Manganese on Microstructure and Mechanical Properties of Shielded Metal Arc-Welded API-X80 Steel  

NASA Astrophysics Data System (ADS)

Microstructure developments of X80 weld metal by the addition of different amounts of alloying elements such as nickel and manganese to the covering of electrodes were investigated. For this reason, samples were welded with electrodes that Ni value has changed between 0.8 and 3.5% in two critical amounts of Mn 0.7 and 1.6. Optical microscopy and scanning electron microscopy were applied for peer investigation of microstructure. Different phase percentages were obtained by Clemex software and compared in all samples. Results indicated that Ni and Mn change weld microstructure in the as-deposited zone and reheated part and corresponding to each alloying element concentration, amount of acicular ferrite, as a determining factor for mechanical properties, were changed.

Sheykh Jaberi, Fariba; Kokabi, A. H.

2012-07-01

83

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

84

Globally sustainable manganese metal production and use.  

PubMed

The "cradle to grave" concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices-such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production of dry-cell batteries, plant fertilizer components, animal feed and colorant for bricks. The manganese ore (high grade 35% manganese) production world wide is about 6 million ton/year and electrolytic manganese metal demand is about 0.7 million ton/year. The total manganese demand is consumed globally by industries including construction (23%), machinery (14%), and transportation (11%). Manganese is recycled within scrap of iron and steel, a small amount is recycled within aluminum used beverage cans. Recycling rate is 37% and efficiency is estimated as 53% [Roskill Metals and Minerals Reports, January 13, 2005. Manganese Report: rapid rise in output caused by Chinese crude steel production. Available from: http://www.roskill.com/reports/manganese.]. Environmentally sustainable management choices include identifying raw material chemistry, utilizing clean production processes, minimizing waste generation, recycling materials, controlling occupational exposures, and collecting representative environmental data. This paper will discuss two electrolytically produced manganese metals, the metal production differences, and environmental impacts cited to date. The two electrolytic manganese processes differ due to the addition of sulfur dioxide or selenium dioxide. Adverse environmental impacts due to use of selenium dioxide methodology include increased water consumption and order of magnitude greater solid waste generation per ton of metal processed. The use of high grade manganese ores in the electrolytic process also reduces the quantity of solid wastes generated during processing. Secondary aluminum facilities have reported hazardous waste generation management issues due to baghouse dusts from rotary furnaces processing selenium contaminated manganese alloys. Environmental impacts resulting from industry are represented by emission inventories of chemical releases to the air, water, and soil. The U.S. metals industry releases reported to EPA Toxic Release Inventory indicate the primary metals industry is the major source of metal air toxic emissions, exceeding electric utility air toxic emissions. The nonferrous metals industry is reported to be the Organization for Economic Co-operation and Development (OECD) most intensive airborne and land pollution source of bioaccumulative metals. However, total waste emissions from industries in the OECD countries have declined due to improving energy consumption. Emission registers and access are improving around the world. However, environmental databases for metal particulates have low confidence ratings since the majority of air toxic emissions are not reported, not monitored, or are estimated based on worst-case emission factors. Environmental assessments including biological monitoring are necessary to validate mandated particulate metal emission reductions and control technologies during metal processing. PMID:19467569

Hagelstein, Karen

2009-09-01

85

Microstructures and Mechanical Properties of Fe-Mn-(Al, Si) TRIP\\/TWIP Steels  

Microsoft Academic Search

The mechanical properties and microstructure of two low carbon high manganese steels with 23.8% (No. 1) and 33% (No. 2) (mass percent) of manganese were investigated. The results showed that No. 1 steel possesses high strength and high plasticity, and No. 2 steel has a relatively high strength and extraordinary plasticity. The No. 1 steel exhibits both TRIP (transformation induced

Hua DING; Zheng-You TANG; Wei LI; Mei WANG; Dan SONG

2006-01-01

86

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

87

Health Hazard Evaluation Determination Report No. HHE-78-074-575, Interlake Steel, Inc., Wilder, Kentucky.  

National Technical Information Service (NTIS)

Environmental and personal air samples were analyzed for manganese (7439965), calcium-oxide (1305788), iron-oxide, and total particulates at Interlake Steel, Inc., (SIC-332) Wilder, Kentucky, on August 30 and 31, 1978. Manganese air concentrations were be...

1979-01-01

88

Effect of aluminum on the hardness, friction coefficient, and wear resistance of austenitic manganese cast irons  

Microsoft Academic Search

1.Aluminum in amounts of 0.4–0.8% decreases the hardness, friction coefficient, and wear of austenitic manganese cast iron containing high concentrations of carbon in contact with lubricated and unlubricated quenched steel.2.The austenitic cast iron in contact with quenched steel has a considerably higher wear resistance and lower friction coefficient as compared to quenched steel on bronze.

V. B. Lyadskii

1964-01-01

89

Nippon Steel Technical Report No. 28, January 1986.  

National Technical Information Service (NTIS)

Table of contents: Low-Temperature Service Facilities and Recent Status of Their Materials and Welding; Development of a High-Strength High Manganese Stainless Steel for Cryogenic Use; High Strength Austenitic Stainless Steel for Cryogenic-Service Structu...

1986-01-01

90

Design of Steel Energy Absorbing Restrainers and Their Incorporation into Nuclear Power Plants for Enhanced Safety. Volume 3. Evaluation of Commercial Steels.  

National Technical Information Service (NTIS)

The low cycle fatigue characteristics of types 301 and 303 stainless steels, Hadfield manganese steel, and 300-M were determined. In relation to the performance of a solid state damping device, Hadfield manganese steel appeared to be most desirable due to...

W. S. Owen R. M. N. Pelloux R. O. Ritchie M. Faral T. Ohhashi

1979-01-01

91

BIOLOGICAL EFFECTS OF MANGANESE  

EPA Science Inventory

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

92

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

93

Search for Nagaoka ferromagnetism in non-magnetic doped semiconductors  

NASA Astrophysics Data System (ADS)

While ferromagnetism at relatively high temperatures is seen in diluted magnetic semiconductors such as Ga1-xMnxAs, under certain conditions semiconductors doped with non-magnetic impurities may also exhibit a ferromagnetic ground state. We investigate the possibility of ferromagnetism in a generalized disordered Hubbard model designed to characterize hydrogenic centers in semiconductors. We demonstrate the occurrence of high spin ground states in clusters (e.g. doped quantum dots), and discuss the nature of the single-particle states in a positionally disordered three-dimensional system with a maximally spin-polarized ground state. In particular, we identify the mobility edges, and describe their dependence on impurity density and potential.

Bhatt, R. N.; Nielsen, E.

2008-04-01

94

Weldability of Cor-Ten B Steel.  

National Technical Information Service (NTIS)

The theoretical and practical information available on the welding of Cor-Ten B steel was collated and shows that application of the precautions defined in BS. 2642 for Carbon-Manganese steels is adequate for the successful fabrication of Cor-Ten B steel ...

J. D. Swindale

1971-01-01

95

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

96

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E.T. Turkdogan 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 higher temperatures than zinc ferrite or zinc titanate. This presentation gives the thermodynamic background for consideration of manganese-based sorbents as an alternative to zinc ferrite. To date the work which has been in progress for nine months is limited at this stage to thermogravimetric testing of four formulations of manganese-alumina sorbents to determine the optimum conditions of pelletization and induration to produce reactive pellets.

Lynch, D.; Hepworth, M.T.

1993-09-01

97

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

98

Large magnetoresistance in non-magnetic silver chalcogenides.  

SciTech Connect

Several materials have been identified over the past few years as promising candidates for the development of new generations of magnetoresistive devices. These range from artificially engineered magnetic multilayers1 and granular alloys2,3, in which the magnetic-field response of interfacial spins modulates electron transport to give rise to 'giant' magnetoresistance4, to the manganite perovskites5, 6, 7, in which metal-insulator transitions driven by a magnetic field give rise to a 'colossal' magnetoresistive response (albeit at very high fields). Here we describe a hitherto unexplored class of magnetoresistive compounds, the silver chalcogenides. At high temperatures, the compounds Ag2S, Ag2Se and Ag2Te are superionic conductors; below approx400 K, ion migration is effectively frozen and the compounds are non-magnetic semiconductors8,9 that exhibit no appreciable magnetoresistance10. We show that slightly altering the stoichiometry can lead to a marked increase in the magnetic response. At room temperature and in a magnetic field of approx55 kOe, Ag2+deltaSe and Ag2+deltaTe show resistance increases of up to 200%, which are comparable with the colossal-magnetoresistance materials. Moreover, the resistance of our most responsive samples exhibits an unusual linear dependence on magnetic field, indicating both a potentially useful response down to fields of practical importance and a peculiarly long length scale associated with the underlying mechanism.

Xu, R.; Husmann, A.; Rosenbaum, T. F.; Saboungi, M.-L.; Enderby, J. E.; Littlewood, P. B.; Materials Science Division; Univ. of Chicago; Bell Lab.

1997-11-01

99

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

100

Occupational exposure to manganese.  

PubMed Central

The relationship between the degree of exposure and biological effects of manganese was studied in a group of 369 workers employed in the production of ferroalloys. Two other groups of workers, from an electrode plant and from an aluminium rolling mill, served as controls. Mean manganese concentrations at work places where ferroalloys were produced varied from 0-301 to 20-442 mg/m3. The exposure level of the two control groups was from 2 to 30 microgram/m3 and from 0-05 to 0-07 microgram/m3, in the electrode plant and rolling mill respectively. Sixty-two (16-8%) manganese alloy workers showed some signs of neurological impairment. These signs were noticeably less in the two control groups (5-8% and 0%) than in the occupationally exposed group. Subjective symptoms, which are nonspecific but may be symptoms of subclinical manganism, were not markedly different in the three groups. However, in the manganese alloy workers some of the subjective symptoms occurred more frequently in heavier smokers than in light smokers or nonsmokers. Heavier smokers engaged in manganese alloy production showed some of the subjective symptoms more often than heavier smokers from the control groups.

Saric, M; Markicevic, A; Hrustic, O

1977-01-01

101

Manganese biomining: A review.  

PubMed

Biomining comprises of processing and extraction of metal from their ores and concentrates using microbial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microorganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their changing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of manganese biomining research operations around the world, identifies factors that drive the selection of biomining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining's future. PMID:21632238

Das, A P; Sukla, L B; Pradhan, N; Nayak, S

2011-08-01

102

MIC of stainless steel in freshwater and the cathodic behaviour of biomineralized Mn-oxides  

Microsoft Academic Search

Microbially influenced corrosion by manganese oxidizing microorganisms (MIC by MOMOs) is a corrosion phenomenon occurring in freshwater systems affecting stainless steels. Typically, chloride induced corrosion is observed at chloride concentrations normally not considered as critical. The initiation of corrosion is attributed to an anodic shift of the open circuit potential of the passive stainless steel caused by manganese dioxide biomineralized

Paul Linhardt

2006-01-01

103

Marine manganese tailings concrete: advantages and drawbacks  

Microsoft Academic Search

Korea, India and China are moving ahead with plans to develop a marine manganese nodule industry. This industry or a related manganese crust, hydrothermal manganese or existing terrestrial manganese industry will dispose millions of tons of fine grained manganese waste. This disposal presents a significant environmental liability. An ideal solution would be to use this material for a beneficial purpose.

John C. Wiltshire; Kathleen A. Moore

1999-01-01

104

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

105

21 CFR 582.5446 - Manganese chloride.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Manganese chloride. 582.5446 Section 582.5446 Food...Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

2013-04-01

106

Bacteriology of Manganese Nodules  

PubMed Central

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

Ehrlich, H. L.

1968-01-01

107

Influence of alloying on the free energy of austenitic grain boundaries in steel  

Microsoft Academic Search

We compute the free energy of austenitic grain boundaries for steels whose carbon content is equal to 0.2%, for chrome-manganese\\u000a steels with various concentrations of molybdenum and phosphorus, and for chrome-manganese-molybdenum steel. On the basis of\\u000a regression analysis, we develop an interpolational model which enables one to estimate (both qualitatively and quantitatively)\\u000a not only the effects of each element on

B. B. Vynokur

1996-01-01

108

Manganese exposures during shielded metal arc welding (SMAW) in an enclosed space.  

PubMed

The work reported here evaluates the effectiveness of various rates of dilution ventilation in controlling welder exposures to manganese in shielded metal arc welding (SMAW) fume when working in enclosed or restricted spaces. Personal and area monitoring using total and respirable sampling techniques, along with multiple analytical techniques, was conducted during the welding operations. With 2000 cubic feet per minute (CFM) (56.63 m3/min) dilution ventilation, personal breathing zone concentrations for the welder using 1/8 inches (3.18 mm) E6010 and E7018 mild steel electrodes were within 75% of the existing threshold limit value (TLV of 0.2 mg/m3 for total manganese and were five times greater than the 2001-2003 proposed respirable manganese TLV of 0.03 mg/m3. Manganese concentrations using high manganese content electrodes were five times greater than those for E6010 and E7018 electrodes. Area samples upstream and downstream of the welder using E6010 and E7018 electrodes exceeded 0.2 mg/m3 manganese. Concentrations inside and outside the welding helmet do not indicate diversion of welding fume by the welding helmet from the welder's breathing zone. There was close agreement between respirable manganese and total manganese fume concentrations. Total fume concentrations measured by gravimetric analysis of matched-weight, mixed cellulose ester filters were comparable to those measured via preweighed PVC filter media. This study indicates that 2000 CFM general dilution ventilation per 29 CFR 1910.252 (c)(2) may not be a sufficient means of controlling respirable manganese exposures for either welders or their helpers in restricted or enclosed spaces. In the absence of site-specific monitoring data indicating otherwise, it is prudent to employ respiratory protection or source capture ventilation for SMAW with E6010, E7018, and high manganese content electrodes rather than depending solely on 2000 CFM general dilution ventilation in enclosed spaces. PMID:16080259

Harris, Michael K; Ewing, William M; Longo, William; DePasquale, Christopher; Mount, Michael D; Hatfield, Richard; Stapleton, Randall

2005-08-01

109

The Nature of the Velocity Field in Molecular Clouds - I. The Non-magnetic Case  

Microsoft Academic Search

We present three numerical simulations of randomly driven, isothermal, non-magnetic, self-gravitating turbulence with different rms Mach numbers Ms and physical sizes L, but approximately the same value of the virial parameter, alpha approx 1.2. We obtain the following results: a) We test the hypothesis that the collapsing centers originate from locally Jeans-unstable (\\

Enrique Vazquez-Semadeni; R. F. Gonzalez; J. Ballesteros-Paredes; A. Gazol; J. Kim

2009-01-01

110

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

111

Thermodynamic modelling of the formation of zinc–manganese ferrite spinel in electric arc furnace dust  

Microsoft Academic Search

Electric arc furnace dust is generated when automobile scrap, containing galvanized steel, is remelted in an electric arc furnace. This dust is considered as a hazardous waste in most countries. Zinc is a major component of the dust and can be of significant commercial value. Typically, the majority of the zinc exists as zinc oxide (ZnO) and as a zinc–manganese

C. A. Pickles

2010-01-01

112

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

113

FATE OF METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL  

EPA Science Inventory

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been proposed as an octane booster for unleaded gasoline; such use could result in ecological and human exposure through surface water and ground water ecosystems. o evaluate the environmental risks from MMT, its environmenta...

114

Hot Coal Gas Desulfurization with manganese based sorbents. Quarterly report, August 1, 1993--September 30, 1993  

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 at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan 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 report documents progress in pelletizing and testing via thermogravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite. Preliminary results indicate that the manganese carbonate material, being of higher purity than the manganese ore, has a higher degree of sulfur capacity and more rapid absorption kinetics. A 2-inch fixed-bed reactor has been fabricated and is now ready for subjecting pellets to cyclic loading and regeneration.

Hepworth, M.T.

1993-10-01

115

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

116

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

117

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

Microsoft Academic Search

The destruction of the ferromagnetism of alloyed SrRuO3 can be caused by electron localization at the substitution sites. Among all the non-magnetic cations that enter the B site, Zr4 + is the least disruptive to conductivity and ferromagnetism. This is because Zr4 + does not cause any charge disorder, and its empty d electron states which are poorly matched in

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

2011-01-01

118

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

119

FMR study of magnetic nanoparticles embedded in non-magnetic matrix  

Microsoft Academic Search

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

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

120

Continuous separation of non-magnetic particles through negative magnetophoresis inside ferrofluids  

Microsoft Academic Search

We present a simple, low-cost, effective, and label-free continuous flow non-magnetic microparticle separation scheme in a microfluidic device under static magnetic fields. The separation process is based on negative magnetophoresis and uses water-based ferrofluids. We exploit the difference in particle sizes to achieve continuous binary separation of fluorescent microparticles with high throughput and efficiency. We demonstrate size-based separation (2.1 ?m

Taotao Zhu; Francisco Marrero; Leidong Mao

2010-01-01

121

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

122

Manganese pavements on the blake plateau.  

PubMed

Dredge samples and photographs from the Blake Plateau, off the southeast coast of the United States, indicate that a layer of manganese oxide forms pavement that may be continuous over an area af about 5000 square kilometers. The manganese pavement grades into round manganese nodules to the south and east and into phosphate nodules to the west. The Gulf Stream probably maintains a very unusual environment that prohibits deposition of clastic sediment and permits accretion of manganese pavements. PMID:17739590

Pratt, R M; McFarlin, P F

1966-03-01

123

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

SciTech Connect

This paper reports the development and successful commercialization of a manganese-molybdenum steel for use in the production of normalized electric resistance welded N-80 casing and tubing. The new steel, nominally a 0.33C, 1.4Mn, 0.23Mo grade, is easily formed and readily welded into pipe. The properties of the new steel are remarkably independent of the coiling temperature on the hot strip mill and the normalizing temperature for both furnace and induction normalizing. This insensitivity to processing variables gives steel producers and ERW pipe manufacturers great flexibility in producing normalized N-80 pipe. Based on subsequent laboratory study, an alternative steel with lower manganese content (1.0%) can achieve required N-80 properties with expected improved casting and forming behavior over steels with higher manganese contents.

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

1984-06-01

124

Autonomic Function in Manganese Alloy Workers  

Microsoft Academic Search

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

William W. Barrington; Carol R. Angle; Nancy K. Willcockson; Marjorie A. Padula; Thomas Korn

1998-01-01

125

Trions as a Probe of Spin Injection Through II-VI Magnetic/Non-Magnetic Heterointerface.  

National Technical Information Service (NTIS)

The authors report on an efficient injection of spin-polarized electrons from Cadmium Magnesium Manganese Tellurium (CdMgMnTe) diluted magnetic semiconductor to nonmagnetic Cadmium Magnesium Tellurium (CdMgTe) quantum well structure. The electron spins we...

E. Janik J. Kossut L. Klopotowski M. Ghali M. Kutrowski

2002-01-01

126

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.

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

2010-01-01

127

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.

Crossgrove, Janelle; Zheng, Wei

2014-01-01

128

Influence of plastic deformation on the properties of ferritic corrosion-resistant steels  

Microsoft Academic Search

1.Ferritic corrosion-resistant steels are characterized by differing instability of the a-solid solution in cold reduction depending upon the silicon, manganese, and chromium contents. With a 15% Cr content in the steel to obtain a ferritic structure stable in reduction it is necessary to add up to 1.5% Si to it. An increase in manganese content to more than 1% leads

N. A. Sorokina; N. V. Andrushova; V. I. Gal'tsova; I. I. Kaputkin

1991-01-01

129

New layered manganese oxide halides.  

PubMed

The first layered manganese(III) oxide chlorides, Sr2MnO3Cl and Sr4Mn3O8-yCl2, have been synthesised; Sr2MnO3Cl adopts a K2NiF4 type structure with sheets of MnO5 square based pyramids linked through oxygen and separated by SrCl layers; it is the end member of a new family of Ruddlesden-Popper type manganese oxide halides which includes the three-layer member Sr4Mn3O8-yCl2 also reported herein. PMID:12120392

Knee, Christopher S; Weller, Mark T

2002-02-01

130

Diode laser heat treatment of lithium manganese oxide films  

NASA Astrophysics Data System (ADS)

The crystallization of lithium manganese oxide thin films prepared by radio frequency magnetron sputtering on stainless steel substrates under 10 Pa argon pressure is demonstrated by a laser annealing technique. Laser annealing processes were developed as a function of annealing time and temperature with the objective to form an electrochemically active lithium manganese oxide cathode. It is demonstrated, that laser annealing with 940 nm diode laser radiation and an annealing time of 2000 s at 600 °C delivers appropriate parameters for formation of a crystalline spinel-like phase. Characteristic features of this phase could be detected via Raman spectroscopy, showing the characteristic main Raman band at 627 cm-1. Within cyclic voltammetric measurements, the two characteristic redox pairs for spinel lithium manganese oxide in the 4 V region could be detected, indicating that the film was well-crystallized and de-/intercalation processes were reversible. Raman post-analysis of a cycled cathode showed that the spinel-like structure was preserved within the cycling process but mechanical degradation effects such as film cracking were observed via scanning electron microscopy. Typical features for the formation of an additional surface reaction layer could be detected using X-ray photoelectron spectroscopy.

Pröll, J.; Kohler, R.; Mangang, A.; Ulrich, S.; Bruns, M.; Seifert, H. J.; Pfleging, W.

2012-04-01

131

Manganese and welding fume exposure and control in construction.  

PubMed

Overexposure to welding fume constituents, particularly manganese, is of concern in the construction industry due to the prevalence of welding and the scarcity of engineering controls. The control effectiveness of a commercially available portable local exhaust ventilation (LEV) unit was assessed. It consisted of a portable vacuum and a small bell-shaped hood connected by a flexible 2 inch (50.8 mm) diameter hose, in both experimental and field settings. The experimental testing was done in a semienclosed booth at a pipefitter training facility. Five paired trials of LEV control vs. no control, each approximately 1 hr in duration and conducted during two successive welds of 6 inch (152.4 mm) diameter carbon steel pipe were run in random order. Breathing zone samples were collected outside the welding hood during each trial. In the field scenario, full-shift breathing zone samples were collected from two pipefitters welding carbon steel pipe for a chiller installation on a commercial construction project. Eight days of full-shift sampling were conducted on both workers (n = 16), and the LEV was used by one of the two workers on an alternating basis for 7 of the days. All samples were collected with personal sample pumps calibrated at 2 L/min. Filter cassettes were analyzed for total particulate and manganese concentration by a certified laboratory. In the experimental setting, use of the portable LEV resulted in a 75% reduction in manganese exposure (mean 13 microg/m(3) vs. 51 microg/m(3); p < 0.05) and a 60% reduction in total particulate (mean 0.74 mg/m(3) vs. 1.83 mg/m(3); p < 0.05). In the field setting, LEV use resulted in a 53% reduction in manganese exposure (geometric mean 46 microg/m(3) vs. 97 microg/m(3); p < 0.05) but only a 10% reduction in total particulate (geometric mean 4.5 mg/m(3) vs. 5.0 mg/m(3); p > 0.05). These results demonstrate that LEV use can reduce manganese exposure associated with welding tasks in construction. PMID:17963139

Meeker, John D; Susi, Pam; Flynn, Michael R

2007-12-01

132

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

133

The space density and X-ray luminosity function of non-magnetic cataclysmic variables  

NASA Astrophysics Data System (ADS)

We combine two complete, X-ray flux-limited surveys, the ROSAT Bright Survey (RBS) and the ROSAT North Ecliptic Pole (NEP) survey, to measure the space density (?) and X-ray luminosity function (?) of non-magnetic cataclysmic variables (CVs). The combined survey has a flux limit of FX? 1.1 × 10-12 erg cm-2 s-1 over most of its solid angle of just over ?, but is as deep as ?10-14 erg cm-2 s-1 over a small area. The CV sample that we construct from these two surveys contains 20 non-magnetic systems. We carefully include all sources of statistical error in calculating ? and ? by using Monte Carlo simulations; the most important uncertainty proves to be the often large errors in distances estimates. If we assume that the 20 CVs in the combined RBS and NEP survey sample are representative of the intrinsic population, the space density of non-magnetic CVs is ?. We discuss the difficulty in measuring ? in some detail - in order to account for biases in the measurement, we have to adopt a functional form for ?. Assuming that the X-ray luminosity function of non-magnetic CVs is a truncated power law, we constrain the power-law index to -0.80 ± 0.05. It seems likely that the two surveys have failed to detect a large, faint population of short-period CVs, and that the true space density may well be a factor of 2 or 3 larger than what we have measured; this is possible, even if we only allow for undetected CVs to have X-ray luminosities in the narrow range 28.7 < log(LX/erg s-1) < 29.7. However, ? as high as 2 × 10-4 pc-3 would require that the majority of CVs has X-ray luminosities below LX= 4 × 1028 erg s-1 in the 0.5-2.0 keV band.

Pretorius, Magaretha L.; Knigge, Christian

2012-01-01

134

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

135

Magnetic manipulation of molecules on a non-magnetic catalytic surface.  

PubMed

Non-magnetic Pt catalysts, supported on carbon coated magnetic Co nanoparticles, changed catalytic performance in the presence of an external magnetic field. This behavior relates to an electronic change of Pt induced by a localized magnetic field, which modifies the CO adsorption geometry. In situ resonant inelastic X-ray scattering (RIXS) experiments and theory reveal the change of atop CO adsorption geometry on the Pt catalyst to bridged geometry under an external magnetic field. This observation opens the possibility of catalytic control by means of an external magnetic field. PMID:23842714

Sá, Jacinto; Szlachetko, Jakub; Sikora, Marcin; Kav?i?, Matjaž; Safonova, Olga V; Nachtegaal, Maarten

2013-09-21

136

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

137

Ionization Ability of Manganese Nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese oxide nanoparticles (Mn-O NPs) were prepared through our novel method as reagents for laser desorption/ionization mass spectrometry (LDI-MS). Through the control of the reaction time in the chemical preparation method (0.5, 1, and 5 h), we succeeded in preparing three different types of manganese oxide particles. The particles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and DC magnetization measurements. These characterization results indicated that the manganese ions oxidized in aqueous alkaline solution, and that the spinel structure was retained for the Mn3O4 phase, which then gradually changed into the MnO2 phase. The mass spectra of substance P (MW = 1347.6) were measured by MALDI-TOF mass spectrometry with Mn-O NPs. The Mn-O NPs that reacted with 3-aminopropyltriethoxysilane(?-APTES) for 1 h or 5 h had higher ionization abilities than those reacted for 0.5 h. These different abilities are attributed to the different crystal structures of the prepared manganese oxides.

Hiroki, Tomoyuki; Shigeoka, Daiki; Kimura, Shinji; Mashino, Toshiyuki; Taira, Shu; Ichiyanagi, Yuko

2011-05-01

138

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

NASA Astrophysics Data System (ADS)

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.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

2014-01-01

139

Metal artifacts in MRI from non-magnetic dental alloy and its FEM analysis.  

PubMed

Artifacts in MR(Magnetic Resonance) images of oral cavity produced from non-magnetic metal restorations was verified by measuring the image of index finger and a cylinder of fat test piece with a type 4 gold alloy ring using a compact MRI equipment. In the images of finger, portion around the ring disappeared. However, it was nearly restored with a cut ring. In the cylinder of fat test piece, obvious artifacts appeared when circumferential surface of the ring was placed perpendicular to RF(Radio Frequency) field of MRI equipment's excitation/detection coil. However, in other directions or with a cut ring, artifact disappeared. The cause was simulated with FEM(Finite Element Method) electromagnetic field analysis, and alternating magnetic field was shown to induce surface current on the continuous gold ring. Magnetic field produced by that current interfered with the field from excitation coil. This demonstrated the characteristics and cause of artifacts by non-magnetic dental metals. PMID:20448408

Taniyama, Tomohide; Sohmura, Taiji; Etoh, Takanori; Aoki, Masaaki; Sugiyama, Eiji; Takahashi, Junzo

2010-05-01

140

New Developments with C-Mn-Ni in High Strength Steel Weld Metals — Part B. Mechanical Properties  

Microsoft Academic Search

Microstructure and properties have been studied for high strength steel weld metals with varia- tions in carbon, manganese and nickel. Based on neural network modelling, experimental welds were made using shielded metal arc welding with manganese at 0.5 or 2.0 wt. % and nickel at 7 or 9 wt. %. Additional welds were made where carbon was varied between 0.03

E. Keehan; L. Karlsson; H.-O. Andrén; L.-E. Svensson

141

Studies on microbiologically influenced corrosion of SS304 by a novel manganese oxidizer, Bacillus flexus.  

PubMed

A manganese oxidizing bacterium was isolated from the surface of steel scraps and biochemical tests and 16S rRNA sequencing analysis confirmed the isolate as Bacillus flexus. Potentiodynamic polarization curves showed ennoblement of open circuit potential, increased passive current, a lowering of breakdown potential, active re-passivation potential and enhanced cathodic current in the presence of B. flexus. Adhesion studies with B. flexus on SS304 specimens with different surface treatments demonstrated decreased adhesion on passivated and FeCl(3) treated specimens due to the removal of MnS inclusions. The present study provides evidence that surface treatment of stainless steels can reduce adhesion of this manganese oxidizing bacterium and decrease the probability of microbiologically influenced corrosion. PMID:21749279

Anandkumar, B; George, R P; Tamilvani, S; Padhy, N; Mudali, U Kamachi

2011-01-01

142

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

143

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2010-07-01

144

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

145

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Barium calcium manganese strontium oxide. ...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. ...The chemical substance identified as barium calcium manganese strontium...

2009-07-01

146

Magnetic ordering in manganese clusters  

NASA Astrophysics Data System (ADS)

Isolated manganese clusters, Mnn,(n=5-22) are deflected by a linear-gradient magnetic field. Mn7-Mn22 are found to deflect uniformly toward high field. The magnitude of the deflections indicate susceptibilities far in excess of those expected based on the susceptibility of bulk manganese, demonstrating that Mn clusters in this size range are magnetically ordered. Per-atom moments obtained from Curie’s Law analysis range from 0.4?b(Mn19) to 1.7?b(Mn12) . For Mn5 and Mn6 , symmetric broadening of the cluster beam is observed, and their moments were determined via line-shape analysis using both free-spin and adiabatic rotor models. The measured moments, interpreted in light of recent density functional theory calculations, suggest that Mn clusters in this size range are molecular ferrimagnets.

Knickelbein, Mark B.

2004-07-01

147

Neurotoxicity of manganese oxide nanomaterials  

Microsoft Academic Search

Manganese (Mn) toxicity in humans has been observed as manganism, a disease that resembles Parkinson’s disease. The mechanism\\u000a of Mn toxicity and the chemical forms that may be responsible for its neurotoxicity are not well understood. We examined the\\u000a toxicity of Mn oxide nanomaterials in a neuronal precursor cell model, using the MTS assay to evaluate mitochondrial function\\u000a in living

Diana M. Stefanescu; Ali Khoshnan; Paul H. Patterson; Janet G. Hering

2009-01-01

148

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.

Greene, Anthony C.; Madgwick, John C.

1991-01-01

149

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

150

[Effect of occupational pollutants containing manganese on some lysosomal enzymes of granulocytes].  

PubMed

The activity of myeloperoxidase and beta-glucuronidase was determined in neutrophil granulocytes of the peripheral blood in workers of steel-works employed at the production of ferrous and manganese alloys. In comparison with the control group granulocytes in metallurgists under study showed significantly higher activity of beta-glucuronidase while an increased activity of myeloperoxidase was found in workers employed for a period exceeding 10 years. PMID:8084260

Misiewicz, A; Radwan, K; Karmoli?ski, M; Gonciarz, R

1994-01-01

151

Studies on microbiologically influenced corrosion of SS304 by a novel manganese oxidizer, Bacillus flexus  

Microsoft Academic Search

A manganese oxidizing bacterium was isolated from the surface of steel scraps and biochemical tests and 16S rRNA sequencing analysis confirmed the isolate as Bacillus flexus. Potentiodynamic polarization curves showed ennoblement of open circuit potential, increased passive current, a lowering of breakdown potential, active re-passivation potential and enhanced cathodic current in the presence of B. flexus. Adhesion studies with B.

B. Anandkumar; R. P. George; S. Tamilvani; N. Padhy; U. Kamachi Mudali

2011-01-01

152

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

PubMed

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

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

2011-03-01

153

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

NASA Astrophysics Data System (ADS)

The destruction of the ferromagnetism of alloyed SrRuO3 can be caused by electron localization at the substitution sites. Among all the non-magnetic cations that enter the B site, Zr4 + is the least disruptive to conductivity and ferromagnetism. This is because Zr4 + does not cause any charge disorder, and its empty d electron states which are poorly matched in energy with the Ru t2g4 states cause the least resonance scattering of Ru's d electrons. Conducting Sr(Ru, Zr)O3 may be used as an electrode for perovskite-based thin film devices, while its insulating counterpart provides unprecedented magnetoresistance, seldom seen in other non-manganite and non-cobaltite perovskites.

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

2011-03-01

154

Mechanism of ferromagnetism in non-magnetic ion-doped zinc oxides  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) that contains non-magnetic ionic dopants, such as nitrogen (N)-doped zinc oxide (ZnO:N), has been observed to exhibit ferromagnetism. Ferromagnetism is proposed to arise from the Coulomb excitation in the localized states that is induced by the oxygen vacancy, V O. A model based on the Coulomb excitation that is associated with the electron-phonon interaction theoretically explains the ferromagnetic mechanism of ZnO:N. This study reveals that the ferromagnetism will be induced by either deep localized states with a small V O concentration or shallow localized states with a high V O concentration. Additionally, electron-phonon coupling either suppresses the ferromagnetism that is induced by the deep donor states of V O or enhances the ferromagnetism that is induced by the shallow donor states of V O.

Sun, Shih-Jye; Yu, Chang-Feng; Hsu, Hua-Shu; Chou, Hsiung; Du, Ai-Jun

2014-01-01

155

Novel 36-membered dodecanuclear manganese metalladiazamacrocycle.  

PubMed

A novel dodecanuclear manganese metalladiazamacrocycle was synthesized employing a new pentadentate ligand N-2-pentenoylsalicylhydrazide (H(3)tpeshz) by supramolecular self-assembly. The backbone of this metal-organic assembly is a repeating unit of an M-N-N-M linkage that extends to complete a 36-membered cyclic structure involving 12 manganese(III) centers. Successive manganese centers are in a chemically different ...ABABAB...-type environment while the chirality varies as ...LambdaLambdaDeltaDeltaLambdaLambda... . The unique arrangement of manganese centers results in a highly puckered metalladiazamacrocycle with an S(6)-point group symmetry. PMID:15568055

John, Rohith P; Lee, Kyungjae; Lah, Myoung Soo

2004-12-01

156

Battles with iron: manganese in oxidative stress protection.  

PubMed

The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron. PMID:22247543

Aguirre, J Dafhne; Culotta, Valeria C

2012-04-20

157

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

158

Alloy compositions and mechanical properties of 9–12% chromium steels with martensitic–austenitic microstructure  

Microsoft Academic Search

Nitrogen alloyed 9–12% chromium steels with high amounts of manganese and nickel have been investigated. The steels are of a lamellar duplex microstructure, consisting of tempered martensite and about 30 vol.% austenite. The martensite is precipitation hardened with fine and homogeneously distributed vanadium nitrides. A good combination of strength and toughness has been achieved, with a room temperature yield strength

U. E Klotz; C Solenthaler; P Ernst; P. J Uggowitzer; M. O Speidel

1999-01-01

159

Manganese and Oxidative Damage in Cucumber  

Microsoft Academic Search

Micronutrients in low or high concentration can affect growth, respiration, photosynthesis, and reproduction in plants. Cucumber (Cucumis sativus, L.) is grown in India in areas low or high in manganese concentration in soils. A study was conducted to investigate the effects of manganese concentration on some metabolic activities affecting developmental responses in cucumber. Seed of cucumber, cv. Sonali, were grown

Rajeev Gopal

2008-01-01

160

Splat cooling of aluminium-manganese alloys  

Microsoft Academic Search

The gun technique of splat cooling is utilized to extend the solid solubility of manganese in aluminium by a factor of four above that at the eutectic temperature. The supersaturated solid solutions can be retained up to 250° C without any significant decomposition. Isochronal and isothermal studies of the variation of the lattice parameter of the 6.4 wt % manganese

S. P. Bhat; T. R. Ramachandran; A. K. Jena

1974-01-01

161

Manganese regulates expression of manganese peroxidase by Phanerochaete chrysosporium.  

PubMed Central

The appearance of manganese peroxidase (MnP) activity in nitrogen-limited cultures of Phanerochaete chrysosporium is dependent on the presence of manganese. Cultures grown in the absence of Mn developed normally and produced normal levels of the secondary metabolite veratryl alcohol but produced no MnP activity. Immunoblot analysis indicated that appearance of MnP protein in the extracellular medium was also dependent on the presence of Mn. Intracellular MnP protein was detectable only in cells grown in the presence of Mn. MnP mRNA was detected by Northern (RNA) blot analysis only in cells grown in the presence of Mn. If Mn was added to 4-day-old nitrogen-limited Mn-deficient cultures, extracellular MnP activity appeared after 6 h and reached a maximum after 18 h. Both actinomycin D and cycloheximide inhibited the induction of MnP activity by Mn. These results indicate that Mn, the substrate of the enzyme, is involved in the transcriptional regulation of the MnP gene. Images

Brown, J A; Glenn, J K; Gold, M H

1990-01-01

162

Dinuclear manganese centers in the manganese-lead-tellurate glasses.  

PubMed

FTIR, UV-VIS and EPR spectra of manganese doped lead-tellurate glasses with composition xMnO·(100-x)[4TeO2·PbO2] where x=0, 1, 5, 10, 20, 30, 40mol% have been studied. The FTIR spectra show the formation of the Mn-O-Pb and Mn-O-Te bridging bonds by increasing of MnO concentration. The UV-VIS spectra show the Mn(+3) species exhibit pronounced absorption, which masks the Mn(+2) spin-forbidden absorption bands when Mn(+2) ions are in high concentrations in these glasses. The EPR spectra exhibit resonance signals characteristic of Mn(+2) ions. The resonance signal located at g?2 is due to Mn(+2) ions in an environment close to octahedral symmetry, whereas the resonance at g?4.3 and 3.3 are attributed to the rhombic surroundings of the Mn(+2) ions. The increase in the MnO content gives rise to absorption at g?2.4 and the paramagnetic ions are involved in dinuclear manganese centers. PMID:21498108

Rada, S; Dehelean, A; Culea, M; Culea, E

2011-07-01

163

Dinuclear manganese centers in the manganese-lead-tellurate glasses  

NASA Astrophysics Data System (ADS)

FTIR, UV-VIS and EPR spectra of manganese doped lead-tellurate glasses with composition xMnO·(100 - x)[4TeO 2·PbO 2] where x = 0, 1, 5, 10, 20, 30, 40 mol% have been studied. The FTIR spectra show the formation of the Mn-O-Pb and Mn-O-Te bridging bonds by increasing of MnO concentration. The UV-VIS spectra show the Mn +3 species exhibit pronounced absorption, which masks the Mn +2 spin-forbidden absorption bands when Mn +2 ions are in high concentrations in these glasses. The EPR spectra exhibit resonance signals characteristic of Mn +2 ions. The resonance signal located at g ? 2 is due to Mn +2 ions in an environment close to octahedral symmetry, whereas the resonance at g ? 4.3 and 3.3 are attributed to the rhombic surroundings of the Mn +2 ions. The increase in the MnO content gives rise to absorption at g ? 2.4 and the paramagnetic ions are involved in dinuclear manganese centers.

Rada, S.; Dehelean, A.; Culea, M.; Culea, E.

2011-07-01

164

Mechanical properties of low-nickel stainless steel  

NASA Technical Reports Server (NTRS)

Demand for improved corrosion-resistant steels, coupled with increased emphasis on conserving strategic metals, has led to development of family of stainless steels in which manganese and nitrogen are substituted for portion of usual nickel content. Advantages are approximately-doubled yield strength in annealed condition, better resistance to stress-corrosion cracking, retention of low magnetic permeability even after severe cold working, excellent strength and ductility at cryogenic temperatures, superior resistance to wear and galling, and excellent high-temperature properties.

Montano, J. W.

1978-01-01

165

Austenite decomposition in ternary manganese, molybdenum and tungsten steels  

NASA Astrophysics Data System (ADS)

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

Hackenberg, Robert Errol

166

Removal of manganese from water using crushed dolomite filtration technique  

Microsoft Academic Search

This paper discusses manganese removal from water by filtration through low cost coarse media. A laboratory scale filtration technique was used to remove manganese from manganese bearing water to prove previous batch studies which showed that the removal of manganese was better in the case of limestone particle as compared to the gravel, crushed brick or with no media addition,

Hamidi A. Aziz; Paul G. Smith

1996-01-01

167

Heating steels in vacuum  

SciTech Connect

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

Marmer, E.N.

1983-03-01

168

Solute Partitioning and Microstructural Development in Dual Phase Steels.  

National Technical Information Service (NTIS)

A systematic study was made of solute partitioning with particular emphasis on the relation between solute partitioning and microstructure formation for low carbon steels containing 1.5 wt% manganese, 2 wt% silicon, and 1 wt% aluminum. Two types of heat t...

M. Ohmura

1985-01-01

169

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

170

New Experimental Evidence on the Incomplete Transformation Phenomenon in Steel.  

SciTech Connect

The aim of this work is to analyse the carbon content distribution in austenite during isothermal bainite formation and the incomplete reaction phenomenon by means of X-ray diffraction analysis and atom-probe tomography in high silicon, manganese alloyed steels. Results provide new evidence on the explanation for the incomplete reaction phenomenon and the bainite transformation theory.

Caballero, Francesca G. [CENIM-CSIC, Madrid, Spain; Garcia-Mateo, C. [CENIM-CSIC, Madrid, Spain; Santofimia, M. J. [Delft University of Technology, Delft, Netherlands; Miller, Michael K [ORNL; Garcia de Andres, C [CENIM-CSIC, Madrid, Spain

2009-01-01

171

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

172

Design of a non-magnetic shielded and integrated electromagnetic tomography system  

NASA Astrophysics Data System (ADS)

The detected signal of an electromagnetic tomography (EMT) system is weak and can be easily disturbed by the capacitance coupling and external magnetic field. In order to improve the performance of the EMT system, simulation of a non-magnetic shield design was done and an integrated EMT system based on a field programmable gate array (FPGA) is presented in this paper. By the orthogonal experiments, the influence of the material, height and inner radius of the shield was investigated according to the uniformity criterion of sensitivity. Besides, the principle for the selection of the shield parameters was put forward. In the present EMT system, a direct digital synthesizer module, digital demodulation module, MCU control module, DA interface module, AD interface module and USB communication module were all integrated in a FPGA chip. The integration of the system is increased and the difficulty of debugging is decreased. The influence of the excitation signal frequency, the sample frequency and the accumulation number of the multiply accumulator intellectual property core on the demodulation was analysed and a general principle was proposed. The system was evaluated and an optimal excitation frequency was chosen. A back-projection algorithm based on a truncated singular value was selected to reconstruct the different distributions, and the speed of reconstruction was 27 frames s-1. The design scheme can be easily transplanted to other electrical tomography systems.

Wang, Chao; Zhang, Junqing; Li, Fanwei; Cui, Ziqiang; Xu, Chuanjin

2011-10-01

173

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

174

Nonlinear detection of spin currents in graphene with non-magnetic electrodes  

NASA Astrophysics Data System (ADS)

The abilities to inject and detect spin carriers are fundamental for research on transport and manipulation of spin information. Pure electronic spin currents have been recently studied in nanoscale electronic devices using a non-local lateral geometry, both in metallic systems and in semiconductors. To unlock the full potential of spintronics we must understand the interactions of spin with other degrees of freedom. Such interactions have been explored recently, for example, by using spin Hall or spin thermoelectric effects. Here we present the detection of non-local spin signals using non-magnetic detectors, through an as-yet-unexplored nonlinear interaction between spin and charge. In analogy to the Seebeck effect, where a heat current generates a charge potential, we demonstrate that a spin current in a paramagnet leads to a charge potential, if the conductivity is energy dependent. We use graphene as a model system to study this effect, as recently proposed. The physical concept demonstrated here is generally valid, opening new possibilities for spintronics.

Vera-Marun, Ivan J.; Ranjan, Vishal; van Wees, Bart J.

2012-04-01

175

Non-magnetic impurity induced magnetism in rutile TiO2:K compounds.  

PubMed

Recent ab initio studies have theoretically predicted room temperature ferromagnetism in several oxide materials of the type AO(2) in which the cation A(4+) is substituted by a non-magnetic element of the 1 A column. Our purpose is to address experimentally the possibility of magnetism in Ti(1-x)K(x)O(2) compounds. The samples have been synthesized via the solid state route method at equilibrium. Our study has shown that Ti(1-x)K(x)O(2) is thermodynamically unstable and leads to a phase separation, in contradiction with the hypothesis of ab initio calculations. In particular, the crystalline TiO(2) grains appear to be surrounded by K-based phase. The oxidization state of the Ti ion is found to be in Ti(4+) as confirmed from the x-ray photoelectron spectra measurement. Nevertheless, K:TiO(2) compounds exhibit weak paramagnetism with the highest magnetic moment of ~0.5 ?(B) K(-1) but no long-range ferromagnetic order. The observed moment in these compounds remains much smaller than the predicted moment of 3 ?(B) by ab initio calculation. The apparent contradictions between our experiments and first-principles studies are discussed. PMID:21997363

Srivastava, S K; Lejay, P; Barbara, B; Boisron, O; Pailhès, S; Bouzerar, G

2011-11-01

176

Non-magnetic impurity induced magnetism in rutile TiO2:K compounds  

NASA Astrophysics Data System (ADS)

Recent ab initio studies have theoretically predicted room temperature ferromagnetism in several oxide materials of the type AO2 in which the cation A4+ is substituted by a non-magnetic element of the 1 A column. Our purpose is to address experimentally the possibility of magnetism in Ti1-xKxO2 compounds. The samples have been synthesized via the solid state route method at equilibrium. Our study has shown that Ti1-xKxO2 is thermodynamically unstable and leads to a phase separation, in contradiction with the hypothesis of ab initio calculations. In particular, the crystalline TiO2 grains appear to be surrounded by K-based phase. The oxidization state of the Ti ion is found to be in Ti4+ as confirmed from the x-ray photoelectron spectra measurement. Nevertheless, K:TiO2 compounds exhibit weak paramagnetism with the highest magnetic moment of ˜0.5 ?B K-1 but no long-range ferromagnetic order. The observed moment in these compounds remains much smaller than the predicted moment of 3 ?B by ab initio calculation. The apparent contradictions between our experiments and first-principles studies are discussed.

Srivastava, S. K.; Lejay, P.; Barbara, B.; Boisron, O.; Pailhès, S.; Bouzerar, G.

2011-11-01

177

Method for the Determination of Cr, Mn, Mo, Ni, and B in Low Alloy Steel Armor Using Atomic Absorption Spectroscopy and Inductively Coupled Argon Plasma Emission Spectroscopy.  

National Technical Information Service (NTIS)

A more reliable, accurate, and rapid method to determine the concentration of chromium, manganese, molybdenum, nickel, and boron in low alloy steel armors is described. The various procedures of sample dissolution by acids are given. For each element, the...

W. K. Chin

1991-01-01

178

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.

Sirkar, Sheela; Amin, J. V.

1974-01-01

179

[Tongue play and manganese deficiency in dairy cattle].  

PubMed

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

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

1995-09-01

180

Solid-state bonding of iron-based alloys, steel–brass, and aluminum alloys  

Microsoft Academic Search

Many genuine solid-state-bonding experiments have been performed using a wide range of metals; the latter includes superplastic ultra-high-carbon steel, Fe–Ni–Si alloy, manganese steel, brass, stainless steel, iron-silicon alloy as well as superplastic aluminum alloys 5083 and 7475. The roll-bonding process was employed to study the ability to mechanically bond (one kind of solid-state bond) iron-based alloys at intermediate temperatures. Press

Horng-Yu Wu; Shyong Lee; Jian-Yih Wang

1998-01-01

181

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

Microsoft Academic Search

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

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

1984-01-01

182

Phase transformational kinetics and hardenability of alloyed medium-carbon steels  

Microsoft Academic Search

The phase transformational kinetics and hardenability of 0.4 pct C steels were studied as influenced by alloying elements,\\u000a singly and in combination. Sixteen series of steels, each containing up to about 0.75 pct Mo, were prepared by laboratory\\u000a induction air melting. The base steels contained manganese, chromium, nickel, silicon, and combinations of these elements\\u000a as alloy additions. Continuous cooling transformation

W. W. Cias; D. V. Doane

1973-01-01

183

Method for removing manganese from water  

US Patent & Trademark Office Database

A process for removal of manganese from water which includes the steps of (i) preparing a fluidized bed of particles (eg. magnetite) in a bioreactor capable of adsorbing a strongly adherent biofilm of microorganisms (e.g. pedomicrobium manganicum) metabolising manganese to provide an actively propagated biomass, and (ii) passing a stream of water through the fluidized bed where manganese is adsorbed by said biomass and is thus removed from the stream of water to provide a purified effluent of water exiting from the bioreactor.

1995-08-22

184

Masking of manganese in relation to stepwise complexometric determination of calcium, magnesium and manganese.  

PubMed

A critical study has been made of the masking of manganese with potassium cyanide in alkaline medium for complexometric titration of calcium and magnesium. It has been found that there is incomplete oxidation to manganese(III) unless the solution is aged for a sufficient period or air is bubbled through the solution at 35 +/- 5 degrees for 10 min. The manganese(III) complex can be reduced with ascorbic acid for titration with EDTA. Procedures are given for stepwise titration of magnesium, manganese and calcium in silicate materials. Mixed indicators are used, to improve the end-points. PMID:18962349

Sinha, B C; Dasgupta, S

185

Biotransformation of manganese oxides by fungi: solubilization and production of manganese oxalate biominerals.  

PubMed

The ability of the soil fungi Aspergillus niger and Serpula himantioides to tolerate and solubilize manganese oxides, including a fungal-produced manganese oxide and birnessite, was investigated. Aspergillus niger and S.?himantioides were capable of solubilizing all the insoluble oxides when incorporated into solid medium: MnO(2) and Mn(2) O(3) , mycogenic manganese oxide (MnO(x) ) and birnessite [(Na(0.3) Ca(0.1) K(0.1) )(Mn(4+) ,Mn(3+) )(2) O(4) ·1.5H(2) O]. Manganese oxides were of low toxicity and A.?niger and S.?himantioides were able to grow on 0.5% (w/v) of all the test compounds, with accompanying acidification of the media. Precipitation of insoluble manganese and calcium oxalate occurred under colonies growing on agar amended with all the test manganese oxides after growth of A.?niger and S.?himantioides at 25°C. The formation of manganese oxalate trihydrate was detected after growth of S.?himantioides with birnessite which subsequently was transformed to manganese oxalate dihydrate. Our results represent a novel addition to our knowledge of the biogeochemical cycle of manganese, and the roles of fungi in effecting transformations of insoluble metal-containing compounds in the environment. PMID:22591055

Wei, Zhan; Hillier, Stephen; Gadd, Geoffrey M

2012-07-01

186

Comparative study in chemistry of microbially and electrochemically induced pitting of 316L stainless steel  

Microsoft Academic Search

Ennoblement of stainless steel (SS) by microbially deposited manganese oxides can lead to pitting corrosion at low chloride concentrations, causing unexpected material failures. We exposed 316L SS to manganese oxidizing bacteria Leptothrix discophora under well-defined laboratory conditions, and then placed the ennobled coupons in a 0.5 M sodium chloride solution until pitting developed. Using time-of-flight secondary ion mass spectroscopy we

X Shi; R Avci; M Geiser; Z Lewandowski

2003-01-01

187

Influence of alloying on the free energy of austenitic grain boundaries in steel  

Microsoft Academic Search

We compute the conditional energy ?, of austenitic grain boundaries and analyze changes in boundary energy at elevated temperatures\\u000a for low-carbon, chrome-manganese and chrome-manganese-molybdcnum steels. It is established that ?, varies within the range\\u000a 1.0–1.3 J\\/m2 and that, in almost all cases of alloying, the effect caused by a decrease in the surface energy of iron is so strong that

B. B. Vynokur

1996-01-01

188

The Nature of the Velocity Field in Molecular Clouds - I. The Non-magnetic Case  

NASA Astrophysics Data System (ADS)

We present three numerical simulations of randomly driven, isothermal, non-magnetic, self-gravitating turbulence with different rms Mach numbers Ms and physical sizes L, but approximately the same value of the virial parameter, alpha approx 1.2. We obtain the following results: a) We test the hypothesis that the collapsing centers originate from locally Jeans-unstable ("super-Jeans"), subsonic fragments; we find no such structures. b) We find that the fraction of small-scale super-Jeans structures is larger in the presence of self-gravity. c) The velocity divergence of subregions of the simulations exhibits a negative correlation with their mean density. d) The density probability density function (PDF) deviates from a lognormal in the presence of self-gravity. e) Turbulence alone in the large-scale simulation does not produce regions with the same size and mean density as those of the small-scale simulation. Items (b)-(e) 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 also measure the star formation rate per free-fall time, 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, the hypotheses of those models neglect the net negative divergence of dense regions we find in our simulations. We conclude that a) part of the observed velocity dispersion in clumps must arise from clump-scale inwards motions, and b) 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.

Vazquez-Semadeni, Enrique; Gonzalez, R. F.; Ballesteros-Paredes, J.; Gazol, A.; Kim, J.

2009-01-01

189

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

190

30-Membered decanuclear manganese metallacrown  

NASA Astrophysics Data System (ADS)

A new macrocyclic decanuclear manganese(III) 30-metallacrowns-10, [Mn 10(ipbmshz) 8(dmpmshz) 2(DMF) 10]. 4DMF ( 1) has been prepared by supramolecular self-assembly and characterized by X-ray crystal diffraction, where ipbmshz 3- is N-(4-isopropylbenzoyl)-3-methylsalicylhydrazide, dmpmshz 3- is N-(2,2-dimethylpropanoyl)-3-methylsalicylhydrazide. The single-crystal structure shows that a novel ring formed by the succession of ten structural moieties of the type [Mn(III)-N-N] through hydrazide N-N groups bridging the ring Mn ions. The ligand enforces the Mn 3+ ions to form the stereochemistry of a propeller configuration with alternate…????…-type chiral forms depending on the steric repulsions between the tail groups. The decanuclear systems measure ˜2.3 nm in diameter and ˜1.2 nm in thickness. The temperature-dependent magnetic properties have been studied and showed the presence of weakly antiferromagnetic couplings between Mn (III) ions.

Lei, Kewei; Shu, Tianpin; Liang, Hongze

2011-10-01

191

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

192

Modulation of cholinergic systems by manganese.  

PubMed

Information on changes in the central nervous system (CNS) cholinergic systems following exposure to manganese are considerably less extensive than that associated with other neurotransmitter systems. However, experimental and clinical evidence support the notion that cholinergic activity plays a key role in the pathophysiology of manganese-induced neurotoxicity. Manganese acts as a chemical stressor in cholinergic neurons in a region-specific manner causing breakdown of the cellular homeostatic mechanisms. In fact, a number of cholinergic synaptic mechanisms are putative targets for manganese activity: presynaptic choline uptake, quantal release of acetylcholine into the synaptic cleft, postsynaptic binding of acetylcholine to receptors and its synaptic degradation by acetylcholinesterase. Moreover, manganese significantly influences astrocytic choline transport systems and astrocytic acetylcholine-binding proteins. Thus, manganese exerts its effect on the highly dynamic reciprocal relationship between astrocytes and cholinergic neurons. Cholinergic afferents are crucial in the physiology of locomotion, cognition, emotion and behavioral response, and therefore, it is not surprising that the anatomical selectivity of most manganese-induced cholinergic effects is compatible with the clinical correlates of manganism, which involves impairment of emotional response, decline in higher cortical functions and movement disorder. Manganism, also referred to as Parkinson's-like disorder, is initially manifested by a neuropsychiatric syndrome (locura manganica), the most frequent symptoms and signs of which are compulsive behavior, emotional lability, visual hallucinations and flight of ideas, cognitive decline and memory loss. These signs and symptoms are followed by an extrapyramidal syndrome, which shares numerous clinical and pathophysiological characteristics with idiopathic Parkinson's disease (PD). This natural history of disease could be a clinical reflection of the preferential involvement of the cholinergic systems, initially in the septo-hippocampus and later in the basal ganglia. These observations highlight the importance of studying the role of the CNS cholinergic systems in manganese-mediated neurotoxicity. PMID:17920128

Finkelstein, Yoram; Milatovic, Dejan; Aschner, Michael

2007-09-01

193

Electrokinetic Removal of Manganese from River Sediment  

Microsoft Academic Search

Manganese was removed from naturally polluted river sediment by applying an electrokinetic remediation technique. The sediment\\u000a was alkaline and had 20% clay, which was mainly illite. The electrokinetic remediation experiments were performed by controlling\\u000a pHs in the electrode cells and reverse electroosmotic flows were observed, i.e., water moved from cathode towards anode. Manganese\\u000a accumulated in areas closer to cathode, however,

Ayten Genc; George Chase; Annabelle Foos

2009-01-01

194

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

PubMed

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

Abbott, P J

1987-12-01

195

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.

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

2011-01-01

196

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

SciTech Connect

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

Hepworth, M.T.

1993-03-01

197

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

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

1986-01-01

198

Pressure Dependence of Superconductivity in RE - Cerium Kondo Systems and Non-Magnetic Uranium Systems.  

NASA Astrophysics Data System (ADS)

The dependence of the superconducting transition temperature T(,c) on impurity concentration n is presented for (1) the Kondo superconducting systems (LaCe)Al(,2) and La(,0.80)Th(,0.20)Ce and (2) the Th-based binary alloys with U solutes at hydrostatic pressures up to about 20 kbar and temperatures as low as 70 mK. The measurements on the Kondo superconductors document the appearance of the pressure induced reentrant phenomenon with two T(,c)'s within certain Ce concentration ranges in both systems. While, with increasing pressure, the re-entrance in the T(,c) vs n phase boundary is preserved for the (LaCe)Al(,2) system, it gradually disappears for the La(,0.80)Th(,0.20)Ce system. The evolution of the T(,c) vs n phase boundary for the latter system exhibits a smooth change in curvature under pressure. This reflects the pressure induced magnetic-non-magnetic transition of Ce impurity ions. While both reentrant superconducting Kondo systems behave similarly at normal pressure, they behave markedly different under hydrostatic pressure. It is observed that the initial depression of T(,c), -dT(,c)/dn(VBAR)(,n=0), for the (LaCe)Al(,2) system increases with pressure, consistent with increasing T(,K)/T(,c(,o)). T(,K) is the Kondo temperature and T(,c(,o)) is the superconducting transition temperature of the host. Surprisingly, -dT(,c)/dn(VBAR)(,n=0) for the La(,0.80)Th(,0.20)Ce system does not change significantly with pressure contrary to the dramatic increase previously observed for LaCe alloys under pressure and for LaThCe alloys by increasing the Th content of the host. The unexpected behavior of the La(,0.80)Th(,0.20)Ce system can be explained if one assumes that each Ce ion in the alloy sees only one of many different nearest neighbor environments. The measurements on the superconducting systems ThXU, X being Y, Sc, Zr, or La, document the effect of U ions when variations are made in host lattice parameter and host average valence. The T(,c) vs n curves for all alloys display exponential-like variations which are described well by the Kaiser expression T(,c) = T(,c(,o)) exp(-An/(1 -Dn)) with adjustable parameters A and D. Systematics are observed between the best fitted parameter A and applied pressure.

Ansari, Parviz Habibollah

199

Pathophysiology of manganese-associated neurotoxicity.  

PubMed

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

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

2012-08-01

200

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.

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

2012-01-01

201

Managing the manganese: molecular mechanisms of manganese transport and homeostasis.  

PubMed

Manganese (Mn) is an essential metal nutrient for plants. Recently, some of the genes responsible for transition metal transport in plants have been identified; however, only relatively recently have Mn2+ transport pathways begun to be identified at the molecular level. These include transporters responsible for Mn accumulation into the cell and release from various organelles, and for active sequestration into endomembrane compartments, particularly the vacuole and the endoplasmic reticulum. Several transporter gene families have been implicated in Mn2+ transport, including cation/H+ antiporters, natural resistance-associated macrophage protein (Nramp) transporters, zinc-regulated transporter/iron-regulated transporter (ZRT/IRT1)-related protein (ZIP) transporters, the cation diffusion facilitator (CDF) transporter family, and P-type ATPases. The identification of mutants with altered Mn phenotypes can allow the identification of novel components in Mn homeostasis. In addition, the characterization of Mn hyperaccumulator plants can increase our understanding of how plants can adapt to excess Mn, and ultimately allow the identification of genes that confer this stress tolerance. The identification of genes responsible for Mn2+ transport has substantially improved our understanding of plant Mn homeostasis. PMID:16101910

Pittman, Jon K

2005-09-01

202

Manganese-electrolysed slag treatment: bioleaching of manganese by Fusarium sp.  

PubMed

A fungi strain named Fusarium sp. was isolated from manganese-electrolysed slag by using a gradient dilution spread plate method, identified by 26S RNA sequence analysis and phylogenetic tree analysis, and explored for the bioleaching capacity to manganese (II) from manganese-electrolysed slag in liquid mineral medium under different environmental conditions, including system temperature, incubator rotation speed and initial pH value. DNA sequence and phylogenetic analysis indicated the name of this fungi strain, that is, Fusarium sp., and higher bioleaching efficiencies (71.6%) of manganese by this fungi were observed when the bioleaching was carried out under the optimized conditions as follows: contact time: 72 h; system temperature: 28 degrees C; inoculums concentration: 2% (v/v); incubator rotation speed: 150 rpm; pH 4.0. Because of its low cost, environment friendliness and better efficiency, the bioleaching technique will have a significant impact on manganese-electrolysed slag pollution mitigation. PMID:22856303

Cao, Jian-Bing; Li, Xiao-Ming; Ouyang, Yu-Zhu; Zheng, Wei; Wang, Dong-Bo; Shen, Ting-Ting; Yue, Xiu; Yang, Qia

2012-06-01

203

Metabolomic Analyses of Body Fluids after Subchronic Manganese Inhalation in Rhesus Monkeys  

Microsoft Academic Search

Neurotoxicity is linked with high-dose manganese inhalation. There are few biomarkers that correlate with manganese exposure. Blood manganese concentrations depend upon the magnitude and duration of the manganese exposure and in- consistently reflect manganese exposure concentrations. The objective of this study was to search for novel biomarkers of manganese exposure in the urine and blood obtained from rhesus monkeys following

David C. Dorman; Melanie F. Struve; Amy Norris; Alan J. Higgins

2008-01-01

204

Structural austenitic stainless steel with superior proof stress and toughness at cryogenic temperatures  

US Patent & Trademark Office Database

Disclosed is a structural austenitic stainless steel with superior proof stress and toughness at cryogenic temperatures. The steel has a composition essentially consisting of, by weight, not greater than 0.05% of carbon, 0.20 to 0.70% of nitrogen, not greater than 1.0% of silicon, not greater than 25% of manganese, 13 to 35% of chromium, 5 to 25% of nickel and the balance substantially iron. The chromium content and manganese content is selected to meet the condition of (Cr+0.9 Mn).gtoreq.20%. The index of cleanliness showing the amount of nonmetallic inclusions is not greater than 0.1%.

1987-06-23

205

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

206

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

NASA Astrophysics Data System (ADS)

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

Acharyya, Rakhi

207

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

PubMed

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

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

1999-01-01

208

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

209

The regional distribution of manganese in the normal human brain  

Microsoft Academic Search

The concentration of manganese per gram dry tissue weight was determined in samples from 39 areas of 8 normal human brains. Manganese was shown to be unevenly distributed with the largest concentrations in the pineal gland and the olfactory bulb. The gray matter yielded a higher content of manganese than the white matter. Significant differences between individuals were found for

Ernesto Bonilla; Enrique Salazar; Jose Joaquin Villasmil; Ruddy Villalobos

1982-01-01

210

The Thermoelectromotive Force of Copper-Manganese Alloys  

Microsoft Academic Search

Thermoelectromotive Force of Alloys of Copper with 5 to 23 Per Cent, Manganese for the Range 0° to 100° C.-The alloys were prepared from electrolytic copper and thermite manganese but contained as impurity about one fiftieth as much iron as manganese. The alloys were cast and then drawn to fine wires. After they had been annealed at 200° C. for

Skezug Kimura; Zunehachi Isawa

1922-01-01

211

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...

212

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

PubMed

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

Zheng, W; Kim, H; Zhao, Q

2000-04-01

213

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

214

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

215

Improved magnesium/manganese dioxide electrochemical cell  

SciTech Connect

The demand for improved energy-storage systems has increased greatly with the evolution of new equipment requiring new and improved battery systems as a power source. Critical characteristics that power sources must accommodate are low cost, high energy density, light weight, and good storability. The present magnesium/manganese dioxide electrochemical system provides high energy density at low cost. A magnesium/manganese dioxide electrochemical cell that has been stored following partial usage is improved by increasing the cathode moisture content at the time of making the cell to reduce the self discharge and increase the operating capacity after the cell has been stored following partial usage.

Jarvis, L.P.; Brundage, M.T.; Atwater, T.

1988-04-14

216

Manganese control during ozonation of water containing organic compounds  

SciTech Connect

Bench-scale tests were conducted to investigate the removal of dissolved manganese from Delaware River water. Prior pilot-plant results had indicated that manganese was not effectively removed by ozonation, sludge blanket clarification, and filtration, because of the breakthrough or resolubilization of colloidal manganese dioxide [MnO[sub 2](s)] species. Increasing the alkalinity was not an effective means of controlling manganese. But application of potassium permanganate after ozonation and at the beginning of coagulation considerably improved the removal of soluble manganese.

Wilczak, A.; Aieta, E.M. (Montgomery Watson, Pasadena, CA (United States)); Knocke, W.R. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)); Hubel, R.E. (American Water Works Service Co., Voorhees, NH (United States))

1993-10-01

217

Component masses of young, wide, non-magnetic white dwarf binaries in the Sloan Digital Sky Survey Data Release 7  

NASA Astrophysics Data System (ADS)

We present a spectroscopic component analysis of 18 candidate young, wide, non-magnetic, double-degenerate binaries identified from a search of the Sloan Digital Sky Survey Data Release 7 (DR7). All but two pairings are likely to be physical systems. We show SDSS J084952.47+471247.7 + SDSS J084952.87+471249.4 to be a wide DA + DB binary, only the second identified to date. Combining our measurements for the components of 16 new binaries with results for three similar, previously known systems within the DR7, we have constructed a mass distribution for the largest sample to date (38) of white dwarfs in young, wide, non-magnetic, double-degenerate pairings. This is broadly similar in form to that of the isolated field population with a substantial peak around M ˜ 0.6 M?. We identify an excess of ultramassive white dwarfs and attribute this to the primordial separation distribution of their progenitor systems peaking at relatively larger values and the greater expansion of their binary orbits during the final stages of stellar evolution. We exploit this mass distribution to probe the origins of unusual types of degenerates, confirming a mild preference for the progenitor systems of high-field-magnetic white dwarfs, at least within these binaries, to be associated with early-type stars. Additionally, we consider the 19 systems in the context of the stellar initial mass-final mass relation. None appear to be strongly discordant with current understanding of this relationship.

Baxter, R. B.; Dobbie, P. D.; Parker, Q. A.; Casewell, S. L.; Lodieu, N.; Burleigh, M. R.; Lawrie, K. A.; Külebi, B.; Koester, D.; Holland, B. R.

2014-06-01

218

Environmental fate of methylcyclopentadienyl manganese tricarbonyl  

Microsoft Academic Search

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

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

1995-01-01

219

21 CFR 184.1452 - Manganese gluconate.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

220

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2013 CFR

...Reg. No. 10024-66-5) is a pale orange or pinkish white powder. It is obtained by precipitating manganese carbonate from...products as defined in § 170.3(n)(29) of this chapter; milk products as defined in § 170.3(n)(31) of this...

2013-04-01

221

21 CFR 184.1461 - Manganese sulfate.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

222

Role of manganese in neurodegenerative diseases  

Microsoft Academic Search

Manganese (Mn) is an essential ubiquitous trace element that is required for normal growth, development and cellular homeostasis. Exposure to high Mn levels causes a clinical disease characterized by extrapyramidal symptom resembling idiopathic Parkinson's disease (IPD). The present review focuses on the role of various transporters in maintaining brain Mn homeostasis along with recent methodological advances in real-time measurements of

Aaron B. Bowman; Gunnar F. Kwakye; Elena Herrero Hernández; Michael Aschner

223

Experimental Observation of Superparamagnetism in Manganese Clusters  

Microsoft Academic Search

A molecular beam of manganese clusters, Mn n \\\\(n = 11-99\\\\), produced at 68 K is deflected toward high field by a gradient field magnet. These results indicate that Mn n clusters in this size range are superparamagnetic species whose intrinsic moments can be determined within the framework of the Langevin model of paramagnetism. Local minima in per-atom magnetic moments

Mark B. Knickelbein

2001-01-01

224

Iron and manganese dynamics in lake water  

Microsoft Academic Search

The speciation and fractionation of iron and manganese compounds from Hinze Dam water samples (Gold Coast City, Queensland, Australia) were studied using atomic absorption spectrophotometry (AAS), electron paramagnetic resonance spectroscopy (EPRS), gel filtration, ion-exchange chromatography, ultrafiltration and various acid digestion regimes. Samples were taken at various depths and times of year, and both filtrate and particulate samples of water column

Myint Zaw; Barry Chiswell

1999-01-01

225

Phase Diagram of Manganese to 40 Kbars.  

National Technical Information Service (NTIS)

Polymorphic transitions in manganese have been investigated up to pressure of 40 kbars by the differential thermal analysis (DTA) technique. The alpha-beta transition temperature increases with pressure with an initial slope of 14.3 plus or minus 0.5C/kb....

E. Rapoport G. C. Kennedy

1965-01-01

226

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.

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

2014-01-01

227

The micro-mechanisms of tempered martensite embrittlement in 4340-type steels  

Microsoft Academic Search

A study of the micro-mechanisms of tempered martensite embrittlement was made on a series of 4340-type steels in which the\\u000a contents of manganese, silicon, and trace impurities, especially phosphorus and sulfur, were varied. One plain-carbon steel\\u000a was also examined. The study employed Charpy impact tests and four-point slow-bend tests coupled with an elastic-plastic stress\\u000a analysis, as well as scanning electron

N. Bandyopadhyay; C. J. McMahon

1983-01-01

228

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

PubMed

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

Pickles, C A

2010-07-15

229

NANO-FINISHING OF STAINLESS-STEEL TUBES USING ROTATIONAL MAGNETORHEOLOGICAL ABRASIVE FLOW FINISHING PROCESS  

Microsoft Academic Search

A new polishing method called Rotational (R)-Magnetorheological Abrasive Flow Finishing (MRAFF) process has been proposed by rotating a magnetic field applied to the Magnetorheological polishing (MRP) medium in addition to the reciprocating motion provided by the hydraulic unit to finish internal surface of cylindrical stainless steel (non-magnetic) workpiece. By intelligently controlling these two motions uniform smooth mirror-like finished surface in

Manas Das; V. K. Jain; P. S. Ghoshdastidar

2010-01-01

230

Cation distribution, structure and magnetic properties of lithium manganese iron oxide spinel solid solutions  

SciTech Connect

Single phase cubic spinel compounds Li {sub x}Mn{sub 1+x}Fe{sub 2-2x}O{sub 4} (x = 0, ..., 1) were obtained by thermal decomposition of freeze-dried formate solutions of appropriate composition. The samples were characterized by X-ray powder diffraction and Rietveld refinement, XANES, {sup 57}Fe Moessbauer spectroscopy and magnetization measurements. The combination of these methods provides useful conclusions concerning the structure, cation distribution and properties of the spinel solid solutions. The Li {sub x}Mn{sub 1+x}Fe{sub 2-2x}O{sub 4} samples contain Mn(II) and Mn(III) or Mn(III) and Mn(IV) for x < 0.5 or x > 0.5, respectively. With the increase of x the portion of Li ions occupying tetrahedral sites increases and becomes 100% at about x = 4/7. In spite of the preferred occupation of octahedral sites by manganese(III), the experimental results can only be explained by a partial occupation also of tetrahedral sites by Mn(III). An increase of M {sub S} with the increase of x (expected for a preferred substitution of magnetic ions in tetrahedral sites by non-magnetic Li ions) is not observed. It should be prevented by the decreasing cooperative coupling effects due to the reduction of the iron content.

Wende, C. [Institute of Inorganic Chemistry, Dresden University of Technology, 01062 Dresden (Germany); Olimov, Kh. [Institute of Physics, University of Bonn, 53115 Bonn (Germany); Modrow, H. [Institute of Physics, University of Bonn, 53115 Bonn (Germany); Wagner, F.E. [Physics Department, Technical University of Munich, 85748 Garching (Germany); Langbein, H. [Institute of Inorganic Chemistry, Dresden University of Technology, 01062 Dresden (Germany)]. E-mail: Hubert.Langbein@chemie.tu-dresden.de

2006-08-10

231

Wear resistance of steels for bimetallic farm machinery parts  

Microsoft Academic Search

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

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

1969-01-01

232

Hardness survey of cold-worked and heat-treated JBK-75 stainless steel alloy  

Microsoft Academic Search

The alloy JBK-75, an age-hardenable austenitic stainless steel, is similar to commercial A-286, but has certain chemistry modifications to improve weldability and hydrogen compatibility. The principal changes are an increase in nickel and a decrease in manganese with lower limits on carbon, phosphorus, sulfur, silicon, and boron. In this study, the effects of solutionizing time and temperature, quench rate, cold

R. J. Jackson; R. L. Lucas

1977-01-01

233

Preliminary studies concerning Hadfield steel behavior during laser beam welding in pulsating regime  

Microsoft Academic Search

This work proposes to analyze the behavior of austenitic manganese - Hadfield steel during laser beam welding in continuous regime. In order to limit the number of experiments, a 24 type factorial experiment was used, with 16 assays, after a frequently used program matrix for these situations. Fusion lines at different service regimes, as well as head to head welds

Ion David; Viorel-Aurel Serban

2007-01-01

234

Corrosion cracking and hydrogen embrittlement of two-phase austenite-ferrite steels  

SciTech Connect

The authors study the resistance to corrosion cracking and hydrogen embrittlement of austenite-ferrite steels based on 25% chromium and 5.5% nickel in a series of destructive mechanical tests in solutions of boiling magnesium chloride. The effects of additions of manganese, yttrium, zirconium, nitrogen, tungsten, and silicon and their abilities to enhance or detract from the resistance are comparatively assessed.

Malkin, V.I.; Fel'dgandler, E.G.

1987-03-01

235

Giant magnetoresistance in non-magnetic phosphoric acid doped polyaniline silicon nanocomposites with higher magnetic field sensing sensitivity.  

PubMed

Phosphoric acid doped conductive polyaniline (PANI) polymer nanocomposites (PNCs) reinforced with silicon nanopowders have been successfully synthesized using a facile surface initiated polymerization (SIP) method. The chemical structures of the nanocomposites are characterized using Fourier transform infrared (FT-IR) spectroscopy. The enhanced thermal stability of the silicon-PANI PNCs compared with pure PANI is obtained using thermogravimetric analysis (TGA). The obtained optical band gap of the PNCs using Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) decreases with increasing silicon loading. The dielectric properties of the PNCs are strongly related to the silicon loading level. Temperature dependent resistivity analysis reveals a quasi 3-D variable range hopping (VRH) electrical conduction mechanism for the synthesized PNCs. Room temperature giant magnetoresistance (GMR) is observed in the synthesized non-magnetic nanocomposites and analyzed using the wave-function shrinkage model. PMID:23698645

Gu, Hongbo; Guo, Jiang; Wei, Huige; Huang, Yudong; Zhao, Cunyu; Li, Ying; Wu, Qingliu; Haldolaarachchige, Neel; Young, David P; Wei, Suying; Guo, Zhanhu

2013-07-14

236

Phase equilibria in the systems vanadium-manganese-boron, molybdenum-manganese-boron, and tungsten-manganese-bor on  

Microsoft Academic Search

Specimens for investigation were prepared from the following components in powder form: vanadium (99.62%), molybdenum (99.98%), tungsten (99.98%), electrolytic manganese (99.8%), and fine-grained boron (99.4%). Thoroughly mixed charges were pressed into compacts weighing 5-10 g each, which were then sintered in a TGV-1M vacuum furnace (vacuum of 0.01 N\\/m 2) for 4 h at a temperature of 1200~ Some of

V. S. Telegus; Yu. B. Kuz'ma

1971-01-01

237

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

PubMed

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 glioblasts with the ability to differentiate into several different types of neuroglia. Cytotoxicity was shown in manganese-treated groups (100, 200, 400, and 800microM of MnCl(2)), and cell viability was decreased to 58.8% of the control group at 2days after treatment with 800microM of MnCl(2). When cells were treated with manganese for 24h, ROS dose-dependently increased while antioxidant intracellular GSH decreased. With the generation of ROS, the increased activity of caspase-3 was shown, and was followed by chromatin condensation and breakage, which is an indication of the cellular apoptotic process. ROS also triggered pro-inflammatory responses in cultured T98G cells, which were demonstrated by the increased gene expression and protein levels of IL-6 and IL-8. PMID:19815061

Park, Eun-Jung; Park, Kwangsik

2010-03-01

238

Kinetics of decomposition of manganese slimes by sulfur dioxide  

SciTech Connect

Lean manganese ores, and slimes obtained during mechanical beneficiation of Chiatura manganese ores, have been treated by the sulfite process, by saturation of suspensions with sulfur dioxide. The kinetics of saturation of the suspensions with sulfur dioxide, and transfer of manganese into solution was studied. Manganese was leached out by passing sulfur dioxide through the slime suspension. The sulfur dioxide dissolved in water to form the weakly dissociated sulfurous acid in equilibrium with its anhydrides. The leaching was conducted without access of air at room temperature. An equation for determination of the rate of sulfur dioxide adsorption by a manganese-containing slurry and for calculation of the degree of manganese extraction into solution was developed from the experimental results. The reaction order and the control regime of the processes were determined.

Dzhaparidze, P.I.; Kelbakiani, N.V.

1982-02-20

239

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).  

Code of Federal Regulations, 2013 CFR

...treated manganese ferrite with acrylic ester polymer (generic). 721.10223 Section...treated manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance...treated manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to...

2013-07-01

240

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

241

Dried leaves — Novel reductant for acid leaching of manganese ore  

Microsoft Academic Search

In the present investigation results on the use of dried leaves as a reductant for manganese ore leaching is reported. A complete\\u000a flow-sheet consisting of steps such as reductive acid leaching, enrichment of leach solution by recycling, iron removal and\\u000a crystallization has been developed for the preparation of manganese sulphate monohydrate from manganese ore of Gujarat Mineral\\u000a Development Corporation (GMDC),

D. Hariprasad; M. K. Ghosh; S. Anand

2009-01-01

242

A microbial fuel cell using manganese oxide oxygen reduction catalysts  

Microsoft Academic Search

Microbial fuel cells (MFCs) are a potential method for enhanced water and waste treatment, which offer the additional benefit\\u000a of energy generation. Manganese oxide was prepared by a simple chemical oxidation using potassium permanganate. Carbon-supported\\u000a manganese oxide nanoparticles were successfully characterised as cathode materials for MFCs. The manganese oxide particles\\u000a when used in a two-chamber MFC, using inoculum from an

I. Roche; K. Katuri; K. Scott

2010-01-01

243

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

244

Lithium Manganese Oxide Prepared by Flux Methods  

Microsoft Academic Search

Plate-like crystals of spinel-type lithium manganese oxide with sizes in the micrometer range were obtained in a flux system\\u000a of LiCl-Mn(NO3)2. The crystals were grown by a dissolution-recrystallization mechanism. Polyhedral crystals with sizes in the millimeter range\\u000a were grown in a flux system of LiCl-Mn(NO3)2 by an evaporation-recrystallization mechanism.

W. Tang; Q. Feng; X. Yang; R. Chitrakar; K. Ooi

245

Preparation and structure of manganese molybdates  

Microsoft Academic Search

Manganese molybdates were prepared by precipitation in aqueous solution. Several monohydrates were obtained in the pH range 3-8. A yellow precipitate that formed initially is also a monohydrate but transforms at 60-100°C into other, more crystalline, products depending upon pH. The compound obtained at pH 7-8 is triclinic, with a = 5.776 (4) A, b = 5.964 (4) A, c

A. Clearfield; A. Moini; P. R. Rudolf

1985-01-01

246

Phase instability of manganese-iron carbides  

Microsoft Academic Search

The stability of carbon saturated manganese-iron alloys was studied by means of simulated decrepitation tests, and it was\\u000a found that the product must contain a minimum of about 5 wt pct iron to be stable during storage. By means of several experimental\\u000a techniques it was shown that the structure of the carbide phase present in carbon saturated ferromanganese determines whether

G. J. W. Kor

1979-01-01

247

Preferential manganese accumulation in dreissenid byssal threads  

Microsoft Academic Search

The elemental composition of byssal threads from two freshwater mussels Dreissena polymorpha (zebra) and Dreissena bugensis (quagga) has been determined by proton-induced X-ray emission spectroscopy. Sulphur and manganese are present at 30–100-fold higher concentrations in the threads than in ambient waters of Lake Erie. Calcium, phosphorus and copper levels are also somewhat enhanced in byssus. Since dreissenid byssus is not

Charles P Swann; Tinuola Adewole; J. Herbert Waite

1998-01-01

248

Manganese transport by caco-2 cells  

Microsoft Academic Search

The uptake and transport kinetics of manganese (Mn) were investigated in the human intestinal Caco-2 cell line both from the\\u000a absorption side (apical to basolateral) and from the exsorption side (basolateral to apical). With regard to the former, transport\\u000a versus time revealed (as uptake) a biphasic pattern with an initial transient phase followed by steady-state conditions. Uptake\\u000a versus Mn concentrations

G. Leblondel; P. Allain

1999-01-01

249

Experimental Observation of Superparamagnetism in Manganese Clusters  

Microsoft Academic Search

A molecular beam of manganese clusters, Mn{sub n} (n=11â99) , produced at 68K is deflected toward high field by a gradient field magnet. These results indicate that Mn{sub n} clusters in this size range are superparamagnetic species whose intrinsic moments can be determined within the framework of the Langevin model of paramagnetism. Local minima in per-atom magnetic moments are observed

Mark Knickelbein; Mark B

2001-01-01

250

Development of third generation advanced high strength steels  

NASA Astrophysics Data System (ADS)

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

McGrath, Meghan Colleen

251

Manganese inhalation as a Parkinson disease model.  

PubMed

The present study examines the effects of divalent and trivalent Manganese (Mn(2+)/Mn(3+)) 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 Mn(2+)/Mn(3+) 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

2010-01-01

252

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.

Ordonez-Librado, Jose Luis; Anaya-Martinez, Veronica; Gutierrez-Valdez, Ana Luisa; Colin-Barenque, Laura; Montiel-Flores, Enrique; Avila-Costa, Maria Rosa

2011-01-01

253

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

254

A biokinetic model for manganese for use in radiation protection  

SciTech Connect

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

Leggett, Richard Wayne [ORNL

2011-01-01

255

Manganese-enhanced magnetic resonance microscopy of mineralization  

USGS Publications Warehouse

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 spectrometry (ICP-MS) results confirm that the manganese content of treated cell pellets was 10-fold higher than that for untreated cell pellets. To establish that manganese is processed like calcium and deposited as bone, calvaria from the skull of embryonic chicks were grown in culture medium supplemented with 1 mM MnCl2 and 3 mM CaCl2. A banding pattern of high and low T2 values, consistent with mineral deposits with high and low levels of manganese, was observed radiating from the calvarial ridge. The results of ICP-MS studies confirm that manganese-treated calvaria take up increasing amounts of manganese with time in culture. Finally, elemental mapping studies with electron probe microanalysis confirmed local variations in the manganese content of bone newly deposited on the calvarial surface. This is the first reported use of manganese-enhanced MRM to study the process whereby calcium is taken up by osteoblasts cells and deposited as bone. ?? 2007 Elsevier Inc. All rights reserved.

Chesnick, I. E.; Todorov, T. I.; Centeno, J. A.; Newbury, D. E.; Small, J. A.; Potter, K.

2007-01-01

256

On the Optimization of Compressibility and Hardenability of Sinter-Hardenable PM Steels  

NASA Astrophysics Data System (ADS)

Sinter-hardenable steel powders eliminate the extra steps normally required for heat treating since they allow for direct quenching of components at the end of the sintering cycle with a forced convection cooling unit. The current article presents the results of the effect of the alloying method on the optimization of compressibility and sinter-hardenability of sinter-hardenable PM steels. Water-atomized steel powders were produced. Two successive designs of experiments were used to optimize the chemical composition with prealloyed (nickel, chromium, molybdenum, and manganese) and admixed elements (nickel, chromium, manganese, and copper). Static mechanical properties were also characterized. Results show that among all of the combinations of chemical elements and within the range of concentrations studied, the optimum sinter-hardenable powder had the following prealloyed chemistry: 1.5 wt pct Ni, 1 to 1.25 wt pct Mo, and 0.40 to 0.55 wt pct Cr.

Giguère, Nicolas; Blais, Carl

2013-10-01

257

Comparative evaluation of oxidative stress status and manganese availability in plants growing on manganese mine  

Microsoft Academic Search

This study pioneered an approach that determined the effects of excess manganese (Mn) on three species; Datura stramonium, Alhagi camelthorn and Chenopodium ambrosioides. We investigated their levels of Mn, antioxidative enzymes and oxidative damage biomarkers in plants (zone 1) in and outside (zone 2) the Mn mine. The results showed that total and available Mn were at toxic levels for

Massod Mashhadi Akbar Boojar; Faranak Goodarzi

2008-01-01

258

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.

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

2012-01-01

259

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

260

An atom probe field ion microscopy study of neutron-irradiated pressure vessel steels  

NASA Astrophysics Data System (ADS)

Atom probe field ion microscopy has revealed that the microstructure of commercial pressure vessel steels that have been neutron-irradiated is extremely complex and involves many different types of features. These features include ultrafine distributions of copper atmospheres, clusters and precipitates, phosphorus clusters, molybdenum carbides and nitrides, and vanadium carbo-nitrides in the matrix. In addition to these ultrafine features, coarse alloy cementite, molybdenum carbides, and copper-manganese precipitates have been observed at grain boundaries. The grain boundaries were also found to be coated with an ultrathin film of molybdenum carbides and nitrides and were enriched in phosphorus, nickel and manganese.

Miller, M. K.; Burke, M. G.

1992-10-01

261

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

262

Electrochromic reactions in manganese oxides I. Raman analysis  

Microsoft Academic Search

Like nickel oxide, manganese oxide is a widely studied material in the primary batteries field. The reactions taking place during voltametric cycling of manganese oxides can be determined using in situ Raman spectroscopy. The main difficulty for the oxide identification is to obtain relevant Raman reference spectra because of the many possible compounds and, for some of these compounds, of

M. C. Bernard; A. Hugot-Le Goff; B. V. Thi; S. Cordoba de Torresi

1993-01-01

263

Np and Pu Sorption to Manganese Oxide Minerals  

Microsoft Academic Search

Manganese oxide minerals are a significant component of the fracture lining mineralogy at Yucca Mountain (Carlos et al., 1993) and within the tuff-confining unit at Yucca Flat (Prothro, 1998), Pahute Mesa (Drellack et al., 1997), and other locations at the Nevada Test Site (NTS). Radionuclide sorption to manganese oxide minerals was not included in recent Lawrence Livermore National Laboratory (LLNL)

P Zhao; M R Johnson; S K Roberts; M Zavarin

2005-01-01

264

Solvent Extraction Separation of Manganese (II) with Tributyl Phosphate  

Microsoft Academic Search

A fast and selective method is proposed for solvent extraction of manganese with tributyl phosphate. It is possible to quantitatively extract manganese with 40% tributyl phosphate in xylene from solutions containing 1 M hydrochloric acid and 2.5 M aluminum chloride as the salting-out agent. The metal from the organic phase is stripped with water and is determined photometrically as its

A. A. Yadav; S. M. Khopkar

1969-01-01

265

Non-heme manganese catalase - the 'other' catalase  

PubMed Central

Non-heme manganese catalases are widely distributed over microbial life and represent an environmentally important alternative to heme-containing catalases in antioxidant defense. Manganese catalases contain a binuclear manganese complex as their catalytic active site rather than a heme, and cycle between Mn2(II,II) and Mn2(III,III) states during turnover. X-ray crystallography has revealed the key structural elements of the binuclear manganese active site complex that can serve as the starting point for computational studies on the protein. Four manganese catalase enzymes have been isolated and characterized, and the enzyme appears to have a broad phylogenetic distribution including both bacteria and archae. More than 100 manganese catalase genes have been annotated in genomic databases, although the assignment of many of these putative manganese catalases needs to be experimentally verified. Iron limitation, exposure to low levels of peroxide stress, thermostability and cyanide resistance may provide the biological and environmental context for the occurrence of manganese catalases.

Whittaker, James W.

2012-01-01

266

Quantification of manganese in human hand bones: a feasibility study  

Microsoft Academic Search

Manganese is both an essential element to human health and also toxic when humans are exposed to excessive levels, particularly by means of inhalation. Biological monitoring of manganese exposure is problematic. It is subject to homeostasis; levels in blood (or serum\\/plasma) reflect only the most recent exposure and rapidly return to within normal ranges, even when there has been a

Aslam; A. Pejovic-Milic; D. R. Chettle; F. E. McNeill

2008-01-01

267

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

268

Sulfide shape control in high strength low alloy steels  

NASA Astrophysics Data System (ADS)

Directionality of mechanical properties—such as toughness and bend formability—is typical of hot rolled steels processed on modern, hot strip mills. In aluminum killed steels, directionality results mainly from elongated (type II) manganese sulfide inclusions. Directionality can be reduced by retaining the original globular shape of the precipitated sulfides. This can be accomplished by promoting the formation of sulfides which are more stable and have a higher melting point than that of manganese sulfide. Thermodynamic considerations indicate that additions of Ti, Zr, Ca, Mg, and rare earths are suitable for this purpose. Experimental work on laboratory heats containing 0.020 to 0.25 pct S involved mainly additions of rare earths (mischmetal or silicides) to a V-Al-N high strength, low alloy steel. Other strong sulfide formers were not utilized either because of too high vapor pressure at steelmaking temperatures or because of their strong interaction with nitrogen. For cerium contents of 0.03 to 0.04 pct, the shape of inclusions, identified as rare earth sulfides, was globular. Control of sulfide shape contributed to a marked improvement in toughness and formability of steel in the direction transverse to the rolling direction. The results have been verified in full scale plant trials.

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

1970-12-01

269

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

270

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.

Aschner, M

2000-01-01

271

Oxidation state of marine manganese nodules  

USGS Publications Warehouse

Analyses of the bulk oxidation state of marine manganese nodules indicates that more than 98% of the Mn in deep ocean nodules is present as Mn(IV). The samples were collected from three quite different areas: the hemipelagic environment of the Guatemala Basin, the pelagic area of the North Pacific, and seamounts in the central Pacific. Results of the study suggest that todorokite in marine nodules is fully oxidized and has the following stoichiometry: (K, Na, Ca, Ba).33(Mg, Cu, Ni).76Mn5O22(H2O)3.2. ?? 1984.

Piper, D. Z.; Basler, J. R.; Bischoff, J. L.

1984-01-01

272

Manganese enzymes with binuclear active sites  

SciTech Connect

The purpose of this article is twofold. First, to review the recent literature dealing with the mechanisms of catalysis by binuclear manganese enzymes. Second, to summarize and illustrate the general principles of catalysis which distinguish binuclear metalloenzymes from monometallic centers. This review covers primarily the published literature from 1991 up to May 1996. A summary of the major structurally characterized dimanganese enzymes is given. These perform various reaction types including several redox reactions, (de)hydrations, isomerizations, (de)phosphorylation, and phosphoryl transfer. 114 refs.

Dismukes, G.C. [Princeton Univ., NJ (United States). Hoyt Lab.] [Princeton Univ., NJ (United States). Hoyt Lab.

1996-11-01

273

Incoherent Charge Dynamics in Perovskite Manganese Oxides  

NASA Astrophysics Data System (ADS)

A minimal model is proposed for the perovskite manganese oxides showing strongly incoherent charge dynamics with a suppressed Drude weight in the ferromagnetic and metallic phase near the insulator. We investigate a generalized double-exchange model whichincludes three elements; the orbital degeneracy of eg conduction bands, the Coulomb interaction and fluctuating Jahn-Teller distortions. We demonstrate that Lanczös diagonalization calculations combined with Monte Carlo sampling of the largely fluctuating lattice distortions result in the optical conductivity which quantitatively accounts for the experimental indications. It is found that all three elements are indispensable for understanding the charge dynamics in these compounds.

Nakano, Hiroki; Motome, Yukitoshi; Imada, Masatoshi

2000-05-01

274

Lithium-manganese oxide rechargeable battery  

SciTech Connect

A new type of rechargeable battery in which lithium ions shuttle between a lithium-manganese oxide electrode and a carbon electrode was unveiled recently by chemists from Bell Communications Research (Bellcore), Red Bank, N.J. The new battery--still experimental--is safer, longer lasting, and potentially cheaper to manufacture than other lithium-ion batteries. In addition, it provides three times the energy of nickel-cadmium cells, the most popular type of rechargeable battery. Bellcore scientists believe the new battery could replace nickel-cadmium and small lead-acid batteries in many applications.

Dagani, R.

1993-01-04

275

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

276

High levels of hair manganese in children living in the vicinity of a ferro-manganese alloy production plant  

Microsoft Academic Search

Manganese (Mn) is an essential element, but an effective toxic at high concentrations. While there is an extensive literature on occupational exposure, few studies have examined adults and children living near important sources of airborne Mn. The objective of this study was to analyze hair Mn of children living in the vicinity of a ferro-manganese alloy production plant in the

José A. Menezes-Filho; Ciro R. Paes; Ângela M. de C. Pontes; Josino C. Moreira; Paula N. Sarcinelli; Donna Mergler

2009-01-01

277

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

278

Experimental Investigation of Shock Initiation in Mixtures of Manganese and Sulfur  

NASA Astrophysics Data System (ADS)

Equimolar mixtures of manganese powder and sulfur at different starting densities were tested in two different types of steel recovery capsules in order to study the shock initiation phenomenon in Self-Propagating High-Temperature Synthesis (SHS) mixtures. Two different sizes of Mn particles were used for these experiments, <10 ?m and -325 mesh (<44 ?m). This mixture was selected due to the large exothermic heat release of the manganese-sulfur reaction (214 kJ/mol), which causes the reaction to be self-sustaining once initiated. The test samples were placed in planar recovery capsules and a strong shock was delivered via the detonation of a charge of amine-sensitized nitromethane. Various shock strengths were achieved by placing different thicknesses of PMMA attenuator discs between the explosive charge and the capsule. The results confirmed that shock-induced reactions can be produced in highly non-porous mixtures. It was also found that shock interactions with the side walls of the recovery capsule can play a significant role in the initiation.

Jetté, F. X.; Goroshin, S.; Higgins, A. J.

2009-12-01

279

Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance  

Microsoft Academic Search

We determined the role of the hyporheic zone (the subsurface zone where stream water and shallow groundwater mix) in enhancing microbially mediated oxidation of dissolved manganese (to form manganese precipitates) in a drainage basin contaminated by copper mining. The fate of manganese is of overall importance to water quality in Pinal Creek Basin, Arizona, because manganese reactions affect the transport

Judson W. Harvey; Christopher C. Fuller

1998-01-01

280

Determination of growth of Sphaerotilus discophorus in the presence of manganese.  

PubMed Central

Manganese interferes strongly with most chemical methods of biomass determination. However, the biomass of manganese-encrusted Sphaerotilus discophorus can be determined after removal of the MnO2 with trichloroacetic acid and oxalic acid. Evidence which indicates that manganese inhibits the heterotrophic growth of S. discophorus and that the cells only oxidize manganese late in the growth curve is presented.

Hajj, H; Makemson, J

1976-01-01

281

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

282

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

283

Amphiphilic pentaazamacrocyclic manganese superoxide dismutase mimetics.  

PubMed

Five newly functionalized pentaazamacrocyclic manganese complexes, with variable lengths and amounts of the aliphatic groups (three compounds with one linear chain containing 12, 16, and 22 carbon atoms, i.e., MnL1, MnL2, and MnL3, respectively, as well as two compounds containing two C12 and C16 chains, MnL4 and MnL5, respectively) that are derivatives of the known SOD mimetic, Mn(Me2-Pyane), have been synthesized. These amphiphilic complexes were characterized by the ESI mass spectrometry, potentiometric titrations, light scattering, cyclic voltammetry, and direct stopped-flow determination of their SOD activity at pH 8.1 and 7.4 (in phosphate and HEPES buffers). The formation of supramolecular aggregates that predominantly exist in the solution as a defined micellar/nanostructure assembly, with an average 400 nm size, has been demonstrated for MnL1. The biological effects of the selected complexes (MnL1 and MnL2) on the superoxide level in cytosol and mitochondria have been tested, as well as their effects on the prevention of the lipid peroxidation induced by paraquat. Advantages and disadvantages of the lipophilic pentaazamacrocyclic manganese SOD mimetics in comparison to the corresponding nonsubstituted SOD active complex have been discussed. PMID:24369718

Lieb, Dominik; Kenkell, Isabell; Miljkovi?, Jan Lj; Moldenhauer, Daniel; Weber, Nadine; Filipovi?, Milos R; Gröhn, Franziska; Ivanovi?-Burmazovi?, Ivana

2014-01-21

284

Manganese-Enhanced Magnetic Resonance Imaging (MEMRI)  

PubMed Central

The use of manganese ions (Mn2+) as an MRI contrast agent was introduced over 20 years ago in studies of Mn2+ toxicity in anesthetized rats (1). Manganese-enhanced MRI (MEMRI) evolved in the late nineties when Koretsky and associates pioneered the use of MEMRI for brain activity measurements (2) as well as neuronal tract tracing (3). Currently, MEMRI has three primary applications in biological systems: (1) contrast enhancement for anatomical detail, (2) activity-dependent assessment and (3) tracing of neuronal connections or tract tracing. MEMRI relies upon the following three main properties of Mn2+: (1) it is a paramagnetic ion that shortens the spin lattice relaxation time constant (T1) of tissues, where it accumulates and hence functions as an excellent T1 contrast agent; (2) it is a calcium (Ca2+) analog that can enter excitable cells, such as neurons and cardiac cells via voltage-gated Ca2+ channels; and (3) once in the cells Mn2+ can be transported along axons by microtubule-dependent axonal transport and can also cross synapses trans-synaptically to neighboring neurons. This chapter will emphasize the methodological approaches towards the use of MEMRI in biological systems.

Massaad, Cynthia A.; Pautler, Robia G.

2012-01-01

285

NON-EQUILIBRIUM CHEMISTRY OF DYNAMICALLY EVOLVING PRESTELLAR CORES. I. BASIC MAGNETIC AND NON-MAGNETIC MODELS AND PARAMETER STUDIES  

SciTech Connect

We combine dynamical and non-equilibrium chemical modeling of evolving prestellar molecular cloud cores and investigate the evolution of molecular abundances in the contracting core. We model both magnetic cores, with varying degrees of initial magnetic support, and non-magnetic cores, with varying collapse delay times. We explore, through a parameter study, the competing effects of various model parameters in the evolving molecular abundances, including the elemental C/O ratio, the temperature, and the cosmic-ray ionization rate. We find that different models show their largest quantitative differences at the center of the core, whereas the outer layers, which evolve slower, have abundances which are severely degenerate among different dynamical models. There is a large range of possible abundance values for different models at a fixed evolutionary stage (central density), which demonstrates the large potential of chemical differentiation in prestellar cores. However, degeneracies among different models, compounded with uncertainties induced by other model parameters, make it difficult to discriminate among dynamical models. To address these difficulties, we identify abundance ratios between particular molecules, the measurement of which would have maximal potential for discrimination among the different models examined here. In particular, we find that the ratios between NH{sub 3} and CO, NH{sub 2} and CO, and NH{sub 3} and HCO{sup +} are sensitive to the evolutionary timescale, and that the ratio between HCN and OH is sensitive to the C/O ratio. Finally, we demonstrate that measurements of the central deviation (central depletion or enhancement) of abundances of certain molecules are good indicators of the dynamics of the core.

Tassis, Konstantinos; Willacy, Karen; Yorke, Harold W.; Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2012-07-01

286

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

287

Steel Rattler  

NASA Astrophysics Data System (ADS)

Steel Rattler is a multi-phased project to determine the feasibility of using commercial off-the-shelf components in an advanced acoustic/seismic unattended ground sensor. This project is supported by the Defense Intelligence Agency through Sandia National Laboratories as the lead development agency. Steel Rattler uses advanced acoustic and seismic detection algorithms to categorize and identify various heavy vehicles down to the number of cylinders in the engine. This detection is accomplished with the capabilities of new, high-speed digital signal processors which analyze both acoustic and seismic data. The resulting analysis is compared against an onboard library of known vehicles and a statistical match is determined. An integrated thermal imager is also employed to capture digital thermal images for subsequent compression and transmission. Information acquired by Steel Rattler in the field is transmitted in small packets by a built-in low-power satellite communication system. The ground station receivers distribute the coded information to multiple analysis sites where the information is reassembled into coherent messages and images.

Trudo, Robert A.; Stotts, Larry G.

1997-07-01

288

Electronic State Calculation of Manganese Dioxide Electrode with Additive Transition Metals  

Microsoft Academic Search

The electronic states of manganese dioxide substituted with transition metals were theoretically calculated by DV-Xalpha method, cluster model was Mn15O56 and Mn14XO56 (X = transition metal). The energy band gap of manganese-X oxides is lower than that of manganese dioxide from theoretical calculation. Also it is identified that the electrical conductivity of manganese-tungsten oxide is better than that of manganese

Bong-Seo Kim; Su-Dong Park; Hee-Woong Lee; Dong-Yoon Lee; Won-Sub Chung

2006-01-01

289

Influence of manganese on enzyme synthesis and citric acid accumulation in Aspergillus niger  

Microsoft Academic Search

Summary A comparison of citric acid fermentations in manganese-deficient and manganese-containing media showed that manganese strongly influences idiophase metabolism. In the presence of manganese, cell growth increases, sugar consumption is diminished and acidogenesis decreases drastically. An investigation of the key enzymes of glycolysis, the pentosephosphate pathway, TCA-cycle, nitrogen metabolism, and gluconeogenesis indicated that manganese deficiency was accompanied by a repression

C. P. Kubicek; M. Röhr

1977-01-01

290

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

SciTech Connect

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

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

2007-04-07

291

Low activation austenitic Mn-steel for in-vessel fusion materials  

NASA Astrophysics Data System (ADS)

Several compositions of austenitic manganese steels (Mn-steels) were investigated for in-vessel component materials in D-T fueled fusion reactor with respect to radiation exposure and waste disposal management. The 24.5Mn-13.5Cr steel was developed in which undesired impurities, such as Ni, Mo, Nb and Co, were controlled and C (˜0.025wt%) and N (˜0.22wt%) contents were well adjusted for corrosion resistance and weldability. Experimental observation has shown that this steel has a single ?-phase structure and good properties for vacuum vessel almost the same grade as Type 316 stainless steel (316SS), such as low permeability, good weldability, good mechanical properties of strength and toughness and good corrosion resistance. Activation calculations were performed adopting this material for the JT-60 Super Upgrade (JT-60SU) vacuum vessel and the effectiveness of low activation was confirmed.

Suzuki, Y.; Saida, T.; Kudough, F.

1998-10-01

292

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.

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

2014-01-01

293

Synthesis of manganese nanoparticles in the liquid phase plasma.  

PubMed

The liquid phase plasma reduction method was applied to prepare the polycrystalline manganese nanoparticles from the solution of manganese chloride tetrahydrate. A bipolar pulsed power supply was used to generate discharge in the aqueous solutions. While large size of dendrite-shaped manganese nanoparticles were mostly observed in the initial stage and particle size decreased with discharge time. The particles were dispersed with less and less small particles by the addition of CTAB and anisotropic shapes nanoparticles were mostly observed at long time plasma-treated. Many spots could be seen in the ED pattern for polycrystalline particles. PMID:24205609

Kim, Hwan-Gi; Lee, Heon; Kim, Sun-Jae; Kim, Do-Heyoung; Kim, Jung-Sik; Kang, Sang-Yong; Jung, Sang-Chul

2013-09-01

294

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

Microsoft Academic Search

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

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

2011-01-01

295

Past Occupational Exposure to Airborne Manganese in a Manganese Alloy Plant  

Microsoft Academic Search

A retrospective exposure assessment of a group of manganese (Mn) alloy workers was performed in conjunction with a 2004 follow-up study, 14 years after cessation of exposure, to evaluate the long-term effects of occupational Mn exposure on neurobehavioral functions. The ferro- and silico-Mn alloy plant opened in 1973 and closed in 1991. The airborne total Mn (TMn) exposures for job

Mary Baldwin; Maryse Bouchard; Fabrice Larribe; Donna Mergler

2008-01-01

296

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:

297

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

298

Hydrogen, acetate, and lactate as electron donors for microbial manganese reduction in a manganese-rich coastal marine sediment.  

PubMed

The role of hydrogen, acetate, and lactate as electron donors for microbial manganese reduction was investigated in manganese-rich marine sediment from Gullmar Fjord (Sweden). Here, manganese reduction accounted for 50% of the anaerobic carbon oxidation at 0-15 cm sediment depth. In anoxic incubations from 0 to 5 cm depth, where manganese reduction dominated completely as terminal electron-accepting process, the combined contribution of acetate and lactate as electron donors for manganese reducers corresponded to < ¼ of the electron flow. The concentrations, ¹?C-radiotracer turnover rates, and contributions to carbon oxidation of acetate and lactate associated with manganese reduction were similar to those found in deeper horizons dominated by concomitant iron and sulfate reduction and sulfate reduction alone, respectively. By contrast, hydrogen concentrations increased considerably with sediment depth, indicating thermodynamic control of the competition between the electron-accepting processes, and hydrogen may have contributed substantially to the > 75% of the electron flow that did not involve acetate and lactate. Alternatively, the oxidation of more complex organic substrates could be involved. Our study provides the first direct evidence of substrate utilization by a natural manganese-reducing community and indicates similar mechanisms of thermodynamic control and competition for electron donors as known from sediments dominated by iron reduction, sulfate reduction, or methanogenesis. PMID:24266405

Vandieken, Verona; Finke, Niko; Thamdrup, Bo

2014-03-01

299

Manganese abundances in Galactic bulge red giants  

NASA Astrophysics Data System (ADS)

Context. Manganese is mainly produced in type II SNe during explosive silicon burning, in incomplete Si-burning regions, and depends on several nucleosynthesis environment conditions, such as mass cut between the matter ejected and falling back onto the remnant, electron and neutron excesses, mixing fallback, and explosion energy. Manganese is also produced in type Ia SNe. Aims: The aim of this work is the study of abundances of the iron-peak element Mn in 56 bulge giants, among which 13 are red clump stars. Four bulge fields along the minor axis are inspected. The study of abundances of Mn-over-Fe as a function of metallicity in the Galactic bulge may shed light on its production mechanisms. Methods: High-resolution spectra were obtained using the FLAMES+UVES spectrograph on the Very Large Telescope. The spectra were obtained within a program to observe 800 stars using the GIRAFFE spectrograph, together with the present UVES spectra. Results: We aim at identifying the chemical evolution of manganese, as a function of metallicity, in the Galactic bulge. We find [Mn/Fe] ~ -0.7 at [Fe/H] ~ -1.3, increasing to a solar value at metallicities close to solar, and showing a spread around - 0.7 ? [Fe/H] ? -0.2, in good agreement with other work on Mn in bulge stars. There is also good agreement with chemical evolution models. We find no clear difference in the behaviour of the four bulge fields. Whereas [Mn/Fe] vs. [Fe/H] could be identified with the behaviour of the thick disc stars, [Mn/O] vs. [O/H] has a behaviour running parallel, at higher metallicities, compared to thick disc stars, indicating that the bulge enrichment might have proceeded differently from that of the thick disc. Observations collected at the European Southern Observatory, Paranal, Chile (ESO programmes 71.B-0617A, 73.B0074A, and GTO 71.B-0196).Tables 1-6 and Figs. 1-6 are available in electronic form at http://www.aanda.org

Barbuy, B.; Hill, V.; Zoccali, M.; Minniti, D.; Renzini, A.; Ortolani, S.; Gómez, A.; Trevisan, M.; Dutra, N.

2013-11-01

300

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

301

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

302

Manganese recovery from secondary resources: a green process for carbothermal reduction and leaching of manganese bearing hazardous waste.  

PubMed

During the hydrometallurgical extraction of zinc by electrowinning process, a hazardous solid waste called anode mud is generated. It contains large quantity of manganese oxides (55-80%) and lead dioxide (6-16%). Due to the presence of a large quantity of lead, the anode mud waste is considered hazardous and has to be disposed of in secure landfills, which is costly, wastes available manganese and valuable land resources. For recovery of manganese content of anode mud, a process comprising of carbothermal treatment using low density oil (LDO) followed by sulphuric acid leaching is developed. PMID:21115220

Chandra, Navin; Amritphale, S S; Pal, Deepti

2011-02-15

303

Impaired manganese metabolism causes mitotic misregulation.  

PubMed

Manganese is an essential trace element, whose intracellular levels need to be carefully regulated. Mn(2+) acts as a cofactor for many enzymes and excess of Mn(2+) is toxic. Alterations in Mn(2+) homeostasis affect metabolic functions and mutations in the human Mn(2+)/Ca(2+) transporter ATP2C1 have been linked to Hailey-Hailey disease. By deletion of the yeast orthologue PMR1 we have studied the impact of Mn(2+) on cell cycle progression and show that an excess of cytosolic Mn(2+) alters S-phase transit, induces transcriptional up-regulation of cell cycle regulators, bypasses the need for S-phase cell cycle checkpoints and predisposes to genomic instability. On the other hand, we find that depletion of the Golgi Mn(2+) pool requires a functional morphology checkpoint to avoid the formation of polyploid cells. PMID:22493290

García-Rodríguez, Néstor; Díaz de la Loza, María del Carmen; Andreson, Bethany; Monje-Casas, Fernando; Rothstein, Rodney; Wellinger, Ralf Erik

2012-05-25

304

Rechargeable alkaline manganese dioxide/zinc batteries  

NASA Astrophysics Data System (ADS)

The rechargeable alkaline manganese dioxide/zinc MnO 2/Zn) system, long established commercial as a primay battery, has reached a high level of performance as a secondary battery system. The operating principles are presented and the technological achievements are surveyed by referencing the recent publications and patent literature. A review is also given of the improvements obtained with newly formulated cathodes and anodes and specially designed batteries. Supported by modelling of the cathode and anode processes and by statistical evidence during cycling of parallel/series-connected modules, the envisioned performance of the next generation of these batteries is described. The possibility of extending the practical use of the improved rechargeable MnO 2/Zn system beyond the field of small electronics into the area of power tools, and even to kW-sized power sources, is demonstrated. Finally, the commercial development in comparison with other rechargeable battery systems is examined.

Kordesh, K.; Weissenbacher, M.

305

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.

2013-01-01

306

Experimental Observation of Superparamagnetism in Manganese Clusters  

SciTech Connect

A molecular beam of manganese clusters, Mn{sub n} (n=11{endash}99) , produced at 68K is deflected toward high field by a gradient field magnet. These results indicate that Mn{sub n} clusters in this size range are superparamagnetic species whose intrinsic moments can be determined within the framework of the Langevin model of paramagnetism. Local minima in per-atom magnetic moments are observed for Mn{sub 13} and Mn{sub 19} , suggestive of an icosahedral growth sequence for the smaller size range. For larger clusters, broad oscillations in the per-atom moments are observed, with a minimum near Mn{sub 32{endash} 37} and a maximum around Mn{sub 50{endash} 56} .

Knickelbein, Mark B.

2001-06-04

307

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.

2013-01-01

308

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

309

Dermal administration of manganese porphyrin by iontophoresis.  

PubMed

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

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

2014-08-01

310

Impaired Manganese Metabolism Causes Mitotic Misregulation*  

PubMed Central

Manganese is an essential trace element, whose intracellular levels need to be carefully regulated. Mn2+ acts as a cofactor for many enzymes and excess of Mn2+ is toxic. Alterations in Mn2+ homeostasis affect metabolic functions and mutations in the human Mn2+/Ca2+ transporter ATP2C1 have been linked to Hailey-Hailey disease. By deletion of the yeast orthologue PMR1 we have studied the impact of Mn2+ on cell cycle progression and show that an excess of cytosolic Mn2+ alters S-phase transit, induces transcriptional up-regulation of cell cycle regulators, bypasses the need for S-phase cell cycle checkpoints and predisposes to genomic instability. On the other hand, we find that depletion of the Golgi Mn2+ pool requires a functional morphology checkpoint to avoid the formation of polyploid cells.

Garcia-Rodriguez, Nestor; Diaz de la Loza, Maria del Carmen; Andreson, Bethany; Monje-Casas, Fernando; Rothstein, Rodney; Wellinger, Ralf Erik

2012-01-01

311

Preparation and structure of manganese molybdates  

SciTech Connect

Manganese molybdates were prepared by precipitation in aqueous solution. Several monohydrates were obtained in the pH range 3-8. A yellow precipitate that formed initially is also a monohydrate but transforms at 60-100/sup 0/C into other, more crystalline, products depending upon pH. The compound obtained at pH 7-8 is triclinic, with a = 5.776 (4) A, b = 5.964 (4) A, c = 6.992 (4) A, ..cap alpha.. = 100.32 (5)/sup 0/, ..beta.. = 95.56 (5)/sup 0/, ..gamma.. = 106.81 (5)/sup 0/, and Z = 2. The structure consists of molybdate tetrahedra and Mn(II) octahedra in which the tetrahedra share four corners with four different octahedra. The water molecule is coordinated to the manganese. Heating any of the hydrates to elevated temperatures converts them to the ..cap alpha..-MnMoO/sub 4/ phase. In contrast, hydrothermal treatment of the hydrates at 200/sup 0/C transforms them to an anhydrous product with the NiWO/sub 4/ structure. A compound, Na/sub 2/Mn/sub 2/(MoO/sub 4/)/sub 3/.3H/sub 2/O, was prepared from alkaline solution. Hydrothermal treatment at 200/sup 0/C converted it to NaMn/sub 2/(O-H)(H/sub 2/O)(MoO/sub 4/)/sub 2/. The structure of this latter phase confirmed the bridging scheme proposed earlier, as it was possible to locate the positrons of the hydrogen atoms. 22 references, 1 figure, 8 table.

Clearfield, A.; Moini, A.; Rudolf, P.R.

1985-12-18

312

Oxidative transformation of carbamazepine by manganese oxides.  

PubMed

This study presents oxidative transformation of carbamazepine by synthetic manganese oxide (?-MnO(2)) as well as impact of variables including initial MnO(2) loading, pH, coexisting metal ions, and humic acid (HA) on transformation. Manganese oxide (?-MnO(2)) was synthesized and stored in the form of suspension. The oxidative reactions were conducted in 50 mL polyethylene (PE) centrifuge tubes with constant pH maintained by buffers. The kinetic experiment was carried out in the solution of pH 2.72 containing 5.0 mg/L of carbamazepine and 130.5 mg/L of MnO(2). Effects of initial MnO(2) loading (0-130.5 mg/L), pH (2.72-8.58) and 0.01 M of coexisting solutes (metal ions and HA) on carbamazepine oxidation were also determined. Reaction kinetics indicated that carbamazepine was rapidly degraded in the first 5 min, and approximately 95 % of carbamazepine was eliminated within 60 min. The reaction exhibited pronounced pH dependence and increased with decreasing pH values. The transformation of carbamazepine was also accelerated with increasing MnO(2) loadings. Coexisting metal ions competed with carbamazepine for reactive sites leading to reduced carbamazepine removal, and the inhibitive capacity followed the order of Mn(2+)?>?Fe(3+)?>?Ca(2+)???Mg(2+). Presence of HA in aqueous solution caused a significant reduction on the magnitude of carbamazepine transformation. This study indicated that carbamazepine can be effectively degraded by ?-MnO(2), and transformation efficiency was strongly dependent on reaction conditions. It suggests that amendment of soil with MnO(2) be a potential alternative to solve carbamazepine pollution. PMID:22565984

He, Yan; Xu, Jian; Zhang, Yuan; Guo, Changsheng; Li, Lei; Wang, Yuqiu

2012-11-01

313

Comparative Methylation Chemistry of Platinum, Palladium, Lead, and Manganese.  

National Technical Information Service (NTIS)

A study was carried out to evaluate the potential for platinum, palladium, lead, and manganese salts and oxides to be biochemically methylated. Methylation is an important, well recognized, determinant of metal toxicity; the striking example being the ext...

R. T. Taylor

1976-01-01

314

Stimulatory effect of boron and manganese salts on keratinocyte migration.  

PubMed

Keratinocyte proliferation and migration are essential for the reconstruction of the cutaneous barrier after skin injury. Interestingly, thermal waters which are rich in trace elements (e.g. boron and manganese), are known to be able to improve wound healing. In order to understand the mechanism of action of this effect, our study investigated the in vitro modulation of keratinocyte migration and proliferation by boron and manganese salts, which are present in high concentrations in a thermal water (Saint Gervais). Our in vitro study demonstrated that incubating keratinocytes for 24 h with boron salts at concentrations between 0.5 and 10 microg/ml or manganese salts at concentrations between 0.1 and 1.5 microg/ml accelerated wound closure compared with control medium (+20%). As this acceleration was not related to an increase in keratinocyte proliferation we suggest that boron and manganese act on wound healing mainly by increasing the migration of keratinocytes. PMID:15202834

Chebassier, Nathalie; Ouijja, El Houssein; Viegas, Isabelle; Dreno, Brigitte

2004-01-01

315

Nucleation and Mineralogical Controls on the Composition of Manganese Nodules.  

National Technical Information Service (NTIS)

Detailed x-ray diffraction, electron microprobe, high pressure equilibration and Mossbauer spectral studies have been made of several manganese nodules, leading to a hypothesis for the formation of these metalliferous deposits on the sea floors. Formation...

R. G. Burns B. A. Brown

1972-01-01

316

Hot coal gas desulfurization with manganese-based sorbents.  

National Technical Information Service (NTIS)

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-...

M. T. Hepworth R. Ben-Slimane

1994-01-01

317

Laboratory Processing and Characterization of Waste Materials from Manganese Nodules.  

National Technical Information Service (NTIS)

The Bureau of Mines report describes the laboratory processing of manganese nodules and the results of tailings characterization obtained during the cooperative program with the Department of Commerce's National Oceanic and Atmospheric Administration (NOA...

B. W. Haynes D. C. Barron G. W. Kramer R. Maeda M. J. Magyar

1985-01-01

318

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.

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

2009-01-01

319

Electrochromic reactions in manganese oxides I. Raman analysis  

SciTech Connect

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

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

1993-11-01

320

Recovery of Manganese from Low-Grade Domestic Sources.  

National Technical Information Service (NTIS)

The objective of the study was to evaluate existing data on low-grade domestic ores, classify the various deposits, determine applicability of promising new beneficiation technologies to these ores, review extraction processes for manganese recovery of th...

S. Malhotra S. Margolin R. F. Machacek V. Vejins W. S. Kelly

1984-01-01

321

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

Microsoft Academic Search

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

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

1994-01-01

322

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

323

[Occupational neurotoxicology due to heavy metals-especially manganese poisoning].  

PubMed

The most hazardous manganese exposures occur in mining and smelting of ore. Recently, the poisoning has been frequently reported to be associated with welding. In occupational exposure, manganese is absorbed mainly by inhalation. Manganese preferentially accumulates in tissues rich in mitochondria. It also penetrates the blood brain barrior and accumulate in the basal ganglia, especially the globus pallidus, but also the striatum. Manganese poisoning is clinically characterized by the central nervous system involvement including psychiatric symptomes, extrapyramidal signs, and less frequently other neurological manifestations, Psychiatric symptomes are well described in the manganese miners and incrude sleep disturbance, disorientation, emotional lability, compulsive acts, hallucinations, illusions, and delusions. The main characteristic manifestations usually begin shortly after the appearance of these psychiatric symptomes. The latter neurological signs are progressive bradykinesia, dystonia, and disturbance of gait. Bradykinesia is one of the most important findings. There is a remarkable slowing of both active and passive movements of the extremities. Micrographia is frequently observed and a characteristic finding. The patients may show some symmetrical tremor, which usually not so marked. The dystonic posture of the limbs is often accompanied by painfull cramps. This attitudal hypertonia has a tenndency to decrease or disappear in the supine position and to increase in orthostation. Cog-wheel rigidity is also elisited on the passive movement of all extremities. Gait disturbance is also characteristic in this poisoning. In the severe cases, cook gait has been reported. The patient uses small steps, but has a tendency to elevate the heels and to rotate them outward. He progress without pressing on the flat of his feet, but only upon the metatarsophalangeal articulations, mainly of the fourth and fifth toes. Increased signal in T1-weighted image in the basal ganglia has been reported in patients with the poisoning. Thus, increasd signal intensities as a target site dose can be a more useful biomakers of the manganese than other biological indicies such as ambient manganese concentration or blood manganese concentration on individual basis. Manganese poisoning ultimately becomes chronic. However, if the disease is diagnosed while still at the early stages and the patient is removed from exposure, the course may be reversed. Once well established, it becomes progressive and irreversible, even when exposure is terminated. Levodopa therapy is not effective for the management of manganese poisoning. Levodopa unresponsiveness may be usefull to distinguish manganese-induced parkinsonism from Parkinson disease. PMID:17585589

Inoue, Naohide

2007-06-01

324

[Effect of an occupational environment containing manganese on granulocyte adherence].  

PubMed

Workers employed in the manufacture of iron/manganese alloys were exposed primarily to manganese, but also to noise and other factors. Neutrophilic erythrocytes of those workers displayed significantly higher adherence compared to that determined in the control group. Duration of employment, occurrence of chronic bronchitis and the intensity of tobacco smoking did not affect the adhesive properties of neutrophilic granulocytes in peripheral blood. PMID:1293473

Misiewicz, A; Jele?, B; Radwan, K

1992-01-01

325

Carbothermal Reduction of Manganese Oxide in Different Gas Atmospheres  

Microsoft Academic Search

Carbothermal reduction of manganese oxides was studied in hydrogen, helium, and argon at different temperatures and carbon-to-manganese\\u000a oxide ratios. Isothermal and temperature programmed carbothermal reduction experiments were conducted in a fixed bed reactor\\u000a 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

Ring Kononov; Oleg Ostrovski; Samir Ganguly

2008-01-01

326

Manganese Metabolism in College Men Consuming Vegetarian Diets  

Microsoft Academic Search

Manganese balance was studied in eight college men consuming a vegetarian diet low in protein. The diet was supplemented with either a vegetable protein food or the vegetable protein food plus skim milk powder. The values for total mean daily manganese intake, excretion and retention were 7.07, 3.74 and 3.34 mg, respectively. The mean daily intake, excretion and retention for

VIRGINIA M. LANG; BARBARA B. NORTH; M. MORSfc

327

Chromium and manganese interactions in streptozocin-diabetic rats  

Microsoft Academic Search

Weanling male rats were fed casein-based diets low in chromium and manganese (-Cr-MN) or supplemented with 1 ppm chromium as chromium chloride (+Cr) and\\/or 55 ppm manganese as manganous carbonate in a factorial design. After 7 weeks on the experimental diets, half of the rats in each group were injected on 2 consecutive days with 55 mg\\/kg streptozocin (STZ) in

M. L. Davis; C. R. Jarrett; B. O. Adeleye; B. J. Stoecker

1991-01-01

328

Oxidation kinetics of manganese (II) in seawater at nanomolar concentrations  

Microsoft Academic Search

Manganese oxidation rates were determined at low (? 20 nM) concentrations in seawater by measuring dissolved manganese (Mn(II)) using flow injection analysis with chemiluminescence detection. Mn(II) was measured in samples that had been filtered (0.2 ?m) and kept in the dark under controlled temperature and pH conditions for time periods up to 6 months. Eight 9 L carboys with mean

Peter J. von Langen; Kenneth S. Johnson; Kenneth H. Coale; Virginia A. Elrod

1997-01-01

329

Interactions between new quinolone antibacterials and diagnostic drug containing manganese.  

PubMed

A diagnostic drug containing manganese chloride tetrahydrate as a major ingredient is available since 2006. It is used in magnetic resonance imaging as a negative contrast medium for magnetic resonance cholangiopancreatography of the gastrointestinal tract. However, there is no report regarding interaction between manganese and new quinolone antibacterials. We investigated the interactions between new quinolone antibacterials and a diagnostic drug containing manganese in vitro. We evaluated the rate of formation of chelate complex by reacting new quinolone antibacterials (levofloxacin, ofloxacin, ciprofloxacin) with a diagnostic drug containing manganese. The EC50 values of the formation of chelate complex for levofloxacin, ofloxacin, and ciprofloxacin were 5.14 ± 0.14, 5.29 ± 0.14, and 0.96 ± 0.04 mM, respectively. The rates of formation of chelate complex by levofloxacin, ofloxacin, and ciprofloxacin in a reaction with the diagnostic drug were 17.0, 18.9, and 55.5 % in clinical condition, respectively. Our results suggest that a complex of each antibacterial and manganese was formed, with ciprofloxacin causing the strongest interaction. In addition, our findings indicate that the degree of interaction may be an important problem in clinical settings with concomitant administration of a new quinolone antibacterial and diagnostic drug containing manganese. PMID:23444035

Hosono, Moeko; Yokoyama, Haruko; Takayanagi, Risa; Yamada, Yasuhiko

2013-12-01

330

Failure of Manganese to Protect from Shiga Toxin  

PubMed Central

Shiga toxin (Stx), the main virulence factor of Shiga toxin producing Escherichia coli, is a major public health threat, causing hemorrhagic colitis and hemolytic uremic syndrome. Currently, there are no approved therapeutics for these infections; however manganese has been reported to provide protection from the Stx1 variant isolated from Shigella dysenteriae (Stx1-S) both in vitro and in vivo. We investigated the efficacy of manganese protection from Stx1-S and the more potent Stx2a isoform, using experimental systems well-established for studying Stx: in vitro responses of Vero monkey kidney cells, and in vivo toxicity to CD-1 outbred mice. Manganese treatment at the reported therapeutic concentration was toxic to Vero cells in culture and to CD-1 mice. At lower manganese concentrations that were better tolerated, we observed no protection from Stx1-S or Stx2a toxicity. The ability of manganese to prevent the effects of Stx may be particular to certain cell lines, mouse strains, or may only be manifested at high, potentially toxic manganese concentrations.

Weiss, Alison A.

2013-01-01

331

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

332

Chronic manganese poisoning in the dry battery industry  

PubMed Central

Emara, A. M., El-Ghawabi, S. H., Madkour, O. I., and El-Samra, G. H. (1971). Brit. J. industr. Med., 28, 78-82. Chronic manganese poisoning in the dry battery industry. A survey was carried out on 36 workers in the dry battery industry exposed to dust containing 65 to 70% manganese oxide. Eight (22·2%) were found to have neuropsychiatric manifestations, six (16·6%) had chronic manganese psychosis, one had left hemi-parkinsonism, and one had left choreoathetosis. An environmental study revealed a high concentration of manganese dust at the main working areas, far exceeding the accepted MAC. The manganese level in blood was almost within the normal range. Coproporphyrin in urine was normal. The electroencephalogram was abnormal in only two of the affected workers (25%) but there was no association between this and the clinical manifestations or duration of exposure. The concentration of manganese dust in air showed some association with the prevalence and rapidity of effect on workers according to their occupation. However, individual susceptibility was apparent. The shortest latent period was one year.

Emara, A. M.; El-Ghawabi, S. H.; Madkour, O. I.; El-Samra, G. H.

1971-01-01

333

Electrochemical impedance spectroscopy and linear polarization applied to evaluation of porosity of phosphate conversion coatings on electrogalvanized steels  

NASA Astrophysics Data System (ADS)

In this work, electrochemical impedance spectroscopy and linear polarization are used in determining porosity of zinc phosphates, and of nickel and manganese modified zinc phosphates on electrogalvanized steel. The porosity of the phosphate layers ranges from 0.1% for the manganese-modified hopeite to 8% for hopeite, using the linear polarization and the electrochemical impedance spectroscopy techniques. The porosity values measured using the two techniques were in agreement. All impedance spectra of coated samples showed two steps, with two capacitive arcs and an inductive looping.

de Freitas Cunha Lins, Vanessa; de Andrade Reis, Geraldo Francisco; de Araujo, Carlos Roberto; Matencio, Tulio

2006-12-01

334

Corrosion resistance of a bent plate from a high-nitrogen nonmagnetic 05Kh22AG15N8M2F steel in aggressive media  

NASA Astrophysics Data System (ADS)

The corrosion resistance of the convex and concave sides of bent plates from a high-nitrogen non-magnetic steel has been studied in aqueous solutions of sulfuric and hydrochloric acids. Weighing and hydrogen methods are used to control the corrosion rate of bent-sample sides and to find a number of effects that complement the picture of the stress corrosion of iron alloys and support the existence of the mechanochemical deformation sign effect.

Esipova, N. E.; Blinov, E. V.; Movchan, T. G.; Bannykh, I. O.

2007-04-01

335

Impedance parameters and the state-of-charge. III. Zinc-manganese dioxide and magnesium-manganese dioxide dry batteries  

Microsoft Academic Search

The problem of non-destructive determination of the state-of-charge of zinc- and magnesium-manganese dioxide dry batteries is examined experimentally from the viewpoint of internal impedance and open-circuit voltage at equilibrium. It is shown that the impedance is mainly charge-transfer controlled at relatively high states-of-charge and progressively changes over to diffusion control as the state-of-charge decreases in the case of zinc-manganese dioxide

M. L. Gopikanth; S. Sathyanarayana

1979-01-01

336

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. 4 figs.

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

1987-02-11

337

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

338

The cause of welding cracks in aircraft steels  

NASA Technical Reports Server (NTRS)

The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.

Muller, J

1940-01-01

339

Intercritical heat treatments in ductile iron and steel  

NASA Astrophysics Data System (ADS)

Materials such as dual phase (DP) steels, transformation induced plasticity (TRIP) steels and dual phase ductile irons are produced by intercritical heat treatments. These materials can provide significant weight savings in the automotive industry. The goal of this dissertation is to study intercritical heat treatments in ductile iron and steel to optimize the production parameters. Three different aspects were addressed. First, common steels were intercritically austenitized and austempered (intercritically austempered) under a variety conditions. The results showed that common grade steels that were intercritically austempered exhibited tensile properties in the same range as DP and TRIP steels. The second study consisted of determining the effect of heat treatment conditions on the tensile properties of intercritically austenitized, quenched and tempered ductile iron (IAQ&TDI). The results showed that (1) ultimate tensile strength (UTS) and yield strength (YS) were determined by the volume fraction of martensite, (2) tempering improved the elongation 1.7-2.5 times with only a slight decrease in strength, (3) the carbon in austenite formed during the intercritical heat treatment of ductile iron with a ferritic-pearlitic matrix came from the carbon available in the matrix and that carbon diffusion from the graphite nodules was restricted, and (4) limited segregation of substitutional elements occurred during intercritical austenitizing. Finally, intercritically austempered ductile iron (IADI) alloyed with different amounts of manganese and nickel was produced. Tensile properties and microstructure were determined. Also, the stability of the austenite during deformation and the lattice strains of the ferrite and the austenite phases were determined using x-ray diffraction (XRD) and neutron diffraction. The results indicated that: 1) high manganese concentrations produced materials with large blocky, low carbon austenite particles at the intercellular boundaries which decreased the elongation of the materials and transformed to martensite during deformation at low strains. 2) Nickel and nickel-manganese alloys formed a combination of blocky and plate-like austenite particles, which were more stable during deformation and either transformed to martensite after yielding or did not transform at all.

Aristizabal, Ricardo E.

340

The effect of microstructure in the hydrogen embrittlement of a gas pipeline steel  

Microsoft Academic Search

Hydrogen embrittlement (HE) tests were carried out on a carbon-manganese pipeline steel having a low sulphur content (<0.01%). It was shown that the susceptibility to HE increased as the microstructures changed from ferrite-pearlite to martensite. In the hydrogenated state the fracture surface of the ferrite-pearlite and ferrite-bainite specimens consisted of small cleavage regions surrounding non-metallic (oxide) inclusions; these were called

T. Alp; T. J. Dames; B. Dogan

1987-01-01

341

Types 304 and 316 stainless steels can experience permanganate pitting in water-handling systems  

SciTech Connect

Five recent installations of types 304 (UNS S30400) and 316 (UNS S31600) stainless steel piping in industrial fresh water-handling systems experienced extremely rapid through-wall penetration by pitting corrosion. The pitting morphology showed some characteristics of microbiologically influenced corrosion, but the pits were not associated with welds. The presence of manganese in the water and the use of chlorination indicated that permanganate ion pitting was responsible.

Kovach, C.W.

1999-09-01

342

Empirical corrosion fatigue life prediction models of a high strength steel  

Microsoft Academic Search

Crack initiation and growth behaviour in plain hour-glass shaped fatigue specimens of quenched and tempered silico-manganese spring steel (BS250 A53) having a mirror image was studied under fully reversed torsional loading conditions in both the laboratory air and the aggressive (0.6 M, aerated NaCl solution) environments. A surface plastic replication technique was used alongwith optical microscopy to monitor the early

G. Murtaza; R. Akid

2000-01-01

343

Effect of oscillation-mark formation on the surface quality of continuously cast steel slabs  

Microsoft Academic Search

In a study of early solidification during the continuous casting of steel slabs, the effect of the formation of oscillation\\u000a marks on the surface quality of the slabs has been examined by metallographic in-vestigation of slab samples and by performing\\u000a a set of mathematical analyses. Positive segregation of solute elements, especially phosphorus and manganese, has been observed\\u000a at the bottom

E. Takeuchi; J. K. Brimacombe

1985-01-01

344

Influence of alloying on the free energy of austenitic grain boundaries in steel  

Microsoft Academic Search

We compute the free energy of boundaries of austenitic grains and analyze the effect of alloying elements (Mo, Ni, V, W, Nb,\\u000a Ce, Cr, Ti, Al, Si, B, and Cu) on the boundary energy of low-carbon, chromemanganese, and chrome-manganese-molybdenum steels.\\u000a By using regression analysis, we develop interpolational models for the qualitative and quantitative evaluation of the effect\\u000a of each element

B. B. Vynokur

1996-01-01

345

Heat treatment giving a stable high temperature micro-structure in cast austenitic stainless steel  

Microsoft Academic Search

A heat-treated cast austenitic stainless steel alloy consisting essentially of about 13-17% chromium, about 13-17% manganese, about 1.5-2.5% molybdenum, about 1.0-2.0% carbon, about 0.5-15% niobium, about 0.5-1.5% silicon, with the balance being iron is described which is produced by the process comprising: casting the alloy; subjecting the alloy to a prebraze heat cycle treatment including heat treating the cast alloy

D. L. Anton; F. D. Lemkey

1988-01-01

346

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

SciTech Connect

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

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

2012-10-10

347

Radiocarbon dating of magnetic and non magnetic soil fractions as a method to estimate the heterotrophic component of soil respiration in a primary forest of Ghana.  

NASA Astrophysics Data System (ADS)

We estimated the heterotrophic component (Rh) of soil respiration in a primary forest of Ghana by radiocarbon dating, a method we already successfully applied in temperate and Mediterranean forests. In this case, given the advanced stage of alteration of tropical soils, which are thus rich in oxides, we implemented the method on soil fractions obtained by High Gradient Magnetic Separation (HGMS), hence based on different degrees of magnetic susceptibility. In particular, we separated an organic pool associated with magnetic minerals (e.g iron oxides) from an organic pool engaged with non-magnetic minerals. This non destructive method of fractionation, often applied to the finest fraction of soil (clay), is here attempted on the bulk fine earth (< 2 mm). We sampled the soil at 0-5, 5-15, 15-10, and 30-50 cm depth intervals, since a previous study in the same site suggested that only the first 50 cm of soil was enriched in bomb carbon (C younger than 1950). The samples of each layer were sieved at 2 mm and further at 0.5 mm ,so as to have two size fractions: 2 to 0.5 mm and <0.5 mm, and both of them were separated into a magnetic and non magnetic fraction. All the specimens were then investigated in terms of mineralogical assemblage (by X-Ray diffrattometry), chemical structure of the organic component (13C NMR spectroscopy), and 14C concentration (AMS) for inferring the mean residence time (MRT) of the organic component in the soil. Radiocarbon concentration was always higher in the finest SOC fractions (<0.5 mm), with the magnetic fraction always showing an higher 14C concentration than the non magnetic one. The magnetic and non magnetic materials of the coarser fraction (0.5-2 mm) showed quite similar 14C concentrations in all of the soil layers investigated. The composition of the organic matter is different in the different fractions and partly explains the differences in MRT, although a major role in preserving the organics from decomposition is probably played by the physical protection in aggregates. Surprisingly, the non magnetic fraction is not influenced at all by the bomb C (negative delta 14) already at a depth of 5-15 cm and, even, at 15-30 cm all the four fractions have pre-bomb C, which means relatively high radiocarbon age. The finest fractions are the main contributors to the Rh flux, particularly the magnetic fraction (<0-5 mm) which show also the higher C concentration among all fractions, opposite to the non-magnetic one that is poorer in C. The Rh flux, estimated from the mean residence time of the fractions and their C amount, allowed to get a more precise estimate with respect to a previous one performed at the same site with radiocarbon analyses on bulk soils. The Rh flux from soil is hard to be estimate based on radiocarbon analysis of the bulk soil alone, and only by means of a SOC fractionation the Rh flux can be estimated quite accurately. This alternative approach for estimating the Rh component of CO2 from soils of tropical areas is currently being applied in 10 tropical forest sites in western and central Africa in the context of the ERC Africa GHG project, and together with measurements of the C inputs annually entering the soil will allow determining the sink-source capacity of primary forest soils.

Chiti, T.; Certini, G.; Marzaioli, F.; Valentini, R.

2012-04-01

348

Manganese(II)-selective PVC membrane electrode based on a pentaazamacrocyclic manganese complex  

Microsoft Academic Search

Manganese(II) complex of 14,16-dimethyl-1,4,7,10,13-pentaazacyclohexadeca-13,16-diene [Me2(16)dieneN5] (I) was synthesized and used in the fabrication of Mn2+-selective ISE membrane in PVC matrix. The membrane having Mn(II) macrocyclic complex as electroactive material along with sodium tetraphenylborate (NaTPB) as anion discriminator and dioctylphthalate (DOP) as plasticizer in poly(vinylchloride) (PVC) matrix was prepared for the determination of Mn2+. The best performance was observed by the

Ashok Kumar Singh; Puja Saxena; Amit Panwar

2005-01-01

349

Homeostatic control of manganese excretion in the neonatal rat  

SciTech Connect

Previous studies in neonatal and suckling animals showed that immature animals have a greatly diminished capacity to excrete manganese and therefore were considered to be unable to regulate tissue manganese concentrations. In contrast, the present studies indicate that suckling rats have the capacity to excrete excess manganese at rates nearly comparable to those of adults. Eight- to 10-day-old rats given a tracer dose of /sup 54/MnCl/sub 2/ (essentially carrier free), either via gavage or by intraperitoneal injection showed little elimination of the /sup 54/Mn until the 18-19th day of life, when there was an abrupt increase in the rate of the metal's excretion. However, when manganese was given in doses of 1 and 10 mg/kg, the young animals excreted from 30-70% of the dose in only 4 days, at which time a new rate of excretion was achieved. This enhanced rate of excretion remained constant until the 18-19th day of life, when it was again accelerated. Biliary excretion of manganese, the primary route for the elimination of the metal, was only 30-60% lower in 14-day-old rats compared with adults at doses ranging from tracer to 10 mg /sup 54/Mn/kg. For both the 14-day-old and adult rats, an apparent biliary transport maximum was reached at a dose of 10 mg Mn/kg. These studies indicate that the excretory pathways for manganese are well developed in the neonatal rat. The avid retention of tracer quantities of manganese by the neonate may be a consequence of the scarcity of this essential trace metal in its diet.

Ballatori, N.; Miles, E.; Clarkson, T.W.

1987-05-01

350

The effect of tempering and aging on a low activation martensitic steel  

NASA Astrophysics Data System (ADS)

Tempering and aging studies were carried out on a martensitic stainless steel which was designed to have reduced long-life activation after exposure to neutrons. Nickel, molybdenum, and niobium additions were restricted in these low activation alloys. The composition of the steel in weight percent was 12 pct Cr, 0.1 pct C, 0.3 pct V, 0.9 pct W, 6.4 pct Mn, and 0.1 pct Si, where manganese is used to stabilize the steel against delta ferrite and tungsten is used for tempering resistance. The tempering conditions studied were 2 hours at 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, and 900 °C and 24 hours at 500 °C and 700 °C. The steel was aged for 1000 and 5000 hours at 365 °C, 420 °C, 520 °C, and 600 °C. Microhardness, optical metallography, and transmission electron microscopy (TEM) were used to characterize the samples. The results indicated that the Ac1 in this steel lies between 700 °C and 800 °C. During the 2-hour tempers at 400 °C and 500 °C, M3C formed. After 24 hours at 500 °C, the M3C was starting to be replaced by M23C6. At higher tempering temperatures and in all the aged samples, M23C6 was the only carbide found. A manganese-rich chi phase was also seen in the samples aged at 420 °C and 520 °C.

Griffin, R. D.; Dodd, R. A.; Kulcinski, G. L.; Gelles, D. S.

1990-07-01

351

?-Amyloid Mediated Nitration of Manganese Superoxide Dismutase  

PubMed Central

Alzheimer’s disease is a multifactorial, progressive, age-related neurodegenerative disease. In familial Alzheimer’s disease, A? is excessively produced and deposited because of mutations in the amyloid precursor protein, presenilin-1, and presenilin-2 genes. Here, we generated a double homozygous knock-in mouse model that incorporates the Swedish familial Alzheimer’s disease mutations and converts mouse A? to the human sequence in amyloid precursor protein and had the P264L familial Alzheimer’s disease mutation in presenilin-1. We observed A? deposition in double knock-in mice beginning at 6 months as well as an increase in the levels of insoluble A?1-40/1-42. Brain homogenates from 3-, 6-, 9-, 12-, and 14-month-old mice showed that protein levels of manganese superoxide dismutase (MnSOD) were unchanged in the double knock-in mice compared to controls. Genotype-associated increases in nitrotyrosine levels were observed. Protein immunoprecipitation revealed MnSOD as a target of this nitration. Although the levels of MnSOD protein did not change, MnSOD activity and mitochondrial respiration decreased in knock-in mice, suggesting compromised mitochondrial function. The compromised activity of MnSOD, a primary antioxidant enzyme protecting mitochondria, may explain mitochondrial dysfunction and provide the missing link between A?-induced oxidative stress and Alzheimer’s disease.

Anantharaman, Muthuswamy; Tangpong, Jitbanjong; Keller, Jeffery N.; Murphy, Michael P.; Markesbery, William R.; Kiningham, Kelley K.; St. Clair, Daret K.

2006-01-01

352

Manganese Neurotoxicity: A Focus on the Neonate  

PubMed Central

Manganese (Mn) is an essential trace metal found in all tissues, and it is required for normal amino acid, lipid, protein, and carbohydrate metabolism. While Mn deficiency is extremely rare in humans, toxicity due to overexposure of Mn is more prevalent. The brain appears to be especially vulnerable. Mn neurotoxicity is most commonly associated with occupational exposure to aerosols or dusts that contain extremely high levels (> 1-5 mg Mn/m3) of Mn, consumption of contaminated well water, or parenteral nutrition therapy in patients with liver disease or immature hepatic functioning such as the neonate. This review will focus primarily on the neurotoxicity of Mn in the neonate. We will discuss putative transporters of the metal in the neonatal brain and then focus on the implications of high Mn exposure to the neonate focusing on typical exposure modes (e.g., dietary and parenteral). Although Mn exposure via parenteral nutrition is uncommon in adults, in premature infants, it is more prevalent, so this mode of exposure becomes salient in this population. We will briefly review some of the mechanisms of Mn neurotoxicity and conclude with a discussion of ripe areas for research in this underreported area of neurotoxicity.

Erikson, Keith M.; Thompson, Khristy; Aschner, Judy; Aschner, Michael

2007-01-01

353

Novel 18-membered hexanuclear manganese metalladiazamacrocycle  

NASA Astrophysics Data System (ADS)

The novel macrocyclic hexanuclear manganese(III) 18-Metallacrowns-6, [Mn 6[(amshz) 6(DMA) 5(H 2O)]·3DMA·H 2O ( 1), has been synthesized by a self-assembly and characterized, where amshz 3- is N-acetyl-4-methyl-salicylhydrazide. The ring is formed by the succession of six structural moieties of the type [Mn(III) sbnd N sbnd N] through hydrazide N sbnd N groups bridging the ring Mn ions. The ligand enforces the metal ions to form the stereochemistry of a propeller configuration with alternate …????…-type chiral forms. The disc molecule offers a oval cavity with an entrance diameter ˜6.7 Å, inner largest diameter ˜9.6 Å and height ˜4.6 Å. The magnetic properties of the metallacrown are characterized by a weak antiferromagnetic exchange interaction, with the value of ?eff = 12.10 ?B at 300 K between the Mn 3+ ion spins with S = 2 in the cyclic system.

Shu, Tian-Pin; Feng, Hai-Mei; Wen, Jun-Long; Pan, Xian-Wei; Lei, Ke-wei; Liang, Hong-Ze

2009-11-01

354

Numerical and Experimental Applications of TWIP Steel in Automotive Parts  

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

355

Intestinal transport of manganese from human milk, bovine milk and infant formula in rats  

SciTech Connect

The transport of manganese from extrinsically labeled human milk, bovine milk and infant formula was studied by the everted intestinal sac method. Tissue/mucosal flux data indicated that transport of manganese into the intestinal tissue was significantly greater with bovine milk and formula than from human milk. Similarly, the total flux of manganese from the mucosal to serosal surface was less when human milk was used. Smaller molecular weight manganese binding ligands isolated from the milk samples enhanced the mucosal to tissue movement of manganese as contrasted to the higher molecular weight manganese binding ligands. Most significantly the data suggest that the transport and uptake of manganese is less in the presence of human milk and its isolated manganese fractions than it is in bovine milk or infant formula. 15 references, 3 tables.

Chan, W.Y.; Bates, J.M. Jr.; Rennert, O.M.; Mahmood, A.; Torres-Pinedo, R.

1984-12-10

356

Manganese sulfide formation via concomitant microbial manganese oxide and thiosulfate reduction.  

PubMed

The dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1 produced ?-MnS (rambergite) nanoparticles during the concurrent reduction of MnO? and thiosulfate coupled to H? oxidation. To investigate effect of direct microbial reduction of MnO? on MnS formation, two MR-1 mutants defective in outer membrane c-type cytochromes (?mtrC/?omcA and ?mtrC/?omcA/?mtrF) were also used and it was determined that direct reduction of MnO? was dominant relative to chemical reduction by biogenic sulfide generated from thiosulfate reduction. Although bicarbonate was excluded from the medium, incubations of strain MR-1 with lactate as the electron donor produced MnCO? (rhodochrosite) as well as MnS in nearly equivalent amounts as estimated by micro X-ray diffraction (micro-XRD) analysis. It was concluded that carbonate released from lactate metabolism promoted MnCO? formation and that Mn(II) mineralogy was strongly affected by carbonate ions even in the presence of abundant sulfide and weakly alkaline conditions expected to favour the precipitation of MnS. Formation of MnS, as determined by a combination of micro-XRD, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction analyses was consistent with equilibrium speciation modelling predictions. Biogenic manganese sulfide may be a manganese sink in the Mn biogeochemical cycle in select environments such as deep anoxic marine basins within the Baltic Sea. PMID:21951417

Lee, Ji-Hoon; Kennedy, David W; Dohnalkova, Alice; Moore, Dean A; Nachimuthu, Ponnusamy; Reed, Samantha B; Fredrickson, James K

2011-12-01

357

Quantification of manganese in human hand bones: a feasibility study.  

PubMed

Manganese is both an essential element to human health and also toxic when humans are exposed to excessive levels, particularly by means of inhalation. Biological monitoring of manganese exposure is problematic. It is subject to homeostasis; levels in blood (or serum/plasma) reflect only the most recent exposure and rapidly return to within normal ranges, even when there has been a temporary excursion in response to exposure. In this context, we have been developing a non-invasive technique for measurement of manganese stored in bone, using in vivo neutron activation analysis. Following preliminary feasibility studies, the technique has been enhanced by two significant infrastructure advances. A specially designed irradiation facility serves to maximize the activation of manganese with respect to the dose of ionizing radiation. Secondly, an array of eight NaI(Tl) crystals provides a detection system with very close to 4 pi geometry. This feasibility study, using neutron activation analysis to measure manganese in the bones of the hand, takes two features into account. Firstly, there is considerable magnesium present in the bone and this produces a spectral interference with the manganese. The 26 Mg(n,gamma)27 Mg reaction produces gamma -rays of 0.843 MeV from the decay of 27 Mg, which interfere with the 0.847 MeV gamma -rays from the decay of 56 Mn,produced by the 55 Mn(n,gamma)56 Mn reaction. Secondly, this work provides estimates of the levels of manganese to be expected in referent subjects. A revised estimate has been made from the most recent literature to explore the potential of the technique as a suitable means of screening patients and people exposed to excessive amounts of Mn who could develop many-fold increased levels of Mn in bones as demonstrated through various animal studies. This report presents the enhancements to the neutron activation system, by which manganese can be measured, which resulted in a detection limit in the hand of human subjects of 1.6 microg/g Ca. It also provides a revised estimate of expected referent levels of manganese in bone, now estimated to be 0.63 microg/g Ca and highlights the extent to which technical improvements will be required to further extend the application of the technique for in vivo measurements in non-exposed human subjects. PMID:18782941

Aslam; Pejovi?-Mili?, A; Chettle, D R; McNeill, F E

2008-08-01

358

Manganese, iron, and total particulate exposures to welders.  

PubMed

Welders are exposed to a variety of metal fumes, including manganese, that may elevate the risk for neurological disease. This study examines several large data sets to characterize manganese, iron, and total particulate mass exposures resulting from welding operations. The data sets contained covariates for a variety of exposure modifiers, including the presence of ventilation, the degree of confinement, and the location of the personal sampler (i.e., behind or in front of the welding helmet). The analysis suggests that exposures to manganese are frequently at or above the current ACGIH(R) threshold limit value of 0.2 mg/m(3). In addition, there is evidence that local exhaust ventilation can control the exposures to manganese and total fume but that mechanical ventilation may not. The data suggest that higher exposures are associated with a greater degree of enclosure, particularly when local exhaust ventilation is absent. Samples taken behind the helmet were, in general, lower than those measured outside of it. There were strong correlations among manganese, iron, and total particulate mass exposures, suggesting simple equations to estimate one fume component from any of the others. PMID:20013450

Flynn, Michael R; Susi, Pam

2010-02-01

359

The sorption of silver by poorly crystallized manganese oxides  

USGS Publications Warehouse

The sorption of silver by poorly crystallized manganese oxides was studied using synthesized samples of three members of the manganous manganite (birnessite) group, of different chemical composition and crystallinity, and a poorly organized ??-MnO2. All four oxides sorbed significant quantities of silver. The manganous manganites showed the greatest sorption (up to 0.5 moles silver/mole MnOx at pH 7) while the ??-MnO2 showed the least (0.3 moles silver/ mole MnOx at pH 7). Sorption of silver was adequately described by the Langmuir equation over a considerable concentration range. The relationship failed at low pH values and high equilibrium silver concentrations. The sorption capacity showed a direct relationship with pH. However, the rate of increase of sorption capacity decreased at the higher pH values. Silver sorption maxima. were not directly related to surface area but appeared to vary with the amount of occluded sodium and potassium present in the manganese oxide. The important processes involved in the uptake of silver by the four poorly crystallized manganese oxides ara considered to be surface exchange for manganese, potassium and sodium as well as exchange for structural manganese, potassium and sodium. ?? 1973.

Anderson, B. J.; Jenne, E. A.; Chao, T. T.

1973-01-01

360

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

PubMed

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

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

2012-01-27

361

Determination of manganese in blood and urine by flameless atomic absorption spectrophotometry.  

PubMed

A method for the determination of manganese in blood and urine is described. A chelate fo manganese with cupferron is extracted with methylisobutylketone and determined by flameless atomic absorption spectrophotometry. The method is directly applicable to urine but the determination of manganese in blood required a preliminary digestion step. With the use of internal standards, this technique allows the determination of manganese concentrations of the order of 1 mug/1 of urine or 1 mug/100 ml whole blood. PMID:1000867

Buchet, J P; Lauwerys, R; Roels, H; De Vos, C

1976-12-01

362

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

363

Non-magnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser melting  

SciTech Connect

The electronic and magnetic effects of intentional compensation with non-magnetic donors are investigated in the ferromagnetic semiconductors Ga1-xMnxAs and Ga1-xMnxP synthesized using ion implantation and pulsed-laser melting (II-PLM). It is demonstrated that compensation with non-magnetic donors and MnI have similarqualitative effects on materials properties. With compensation TC decreases, resistivity increases, and stronger magnetoresistance and anomalous Hall effect attributed to skew scattering are observed. Ga1-xMnxAs can be controllably compensated with Te through a metal-insulator transition through which the magnetic and electrical properties vary continuously. The resistivity of insulating Ga1-xMnxAs:Te can be described by thermal activation to the mobility edge and simply-activated hopping transport. Ga1-xMnxP doped with S is insulating at all compositions but shows decreasing TC with compensation. The existence of a ferromagnetic insulating state in Ga1-xMnxAs:Te and Ga1-xMnxP:S having TCs of the same order as the uncompensated materials demonstrates that localized holes are effective at mediating ferromagnetism in ferromagnetic semiconductors through the percolation of ferromagnetic 'puddles' which at low temperatures.

Scarpulla, M.A.; Stone, P.R.; Sharp, I.D.; Haller, E.E.; Dubon, O.D.; Beeman, J.W.; Yu, K.M.

2008-02-05

364

ACID LEACHING AND ELECTROCHEMICAL RECOVERY OF MANGANESE FROM SPENT ALKALINE BATTERIES  

Microsoft Academic Search

This paper discusses a procedure for manganese recovery as manganese dioxide by anodic oxidation of acid solutions obtained by leaching of spent alkaline batteries with sulfuric acid. Spent size D alkaline batteries were dismantled, separating case, contacts and separator from the reactive paste. A series of laboratory tests were conducted to define the best conditions for manganese and zinc extraction

C. A. Andrade Tacca; M. M. E. Duarte

365

Biogenic manganese oxides: Formation mechanisms, mineralogy and environmental relevance Term paper: Biogeochemistry and pollutant dynamics  

Microsoft Academic Search

Biogenic manganese oxides can be a tool for soil remediation. Recent papers are reviewed to gather information on their formation mechanisms, mineralogy and environmental relevance. Characterisations of the manganese oxidation products of the bacteria groups Bacillus sp., Pseudomonas putida and Leptothrix discophora are described and compared. The biochemical path- ways of bacterial manganese oxidation are discussed. It seems, that bacteria

Ruben Kretzschmar

366

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 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 )...

2009-07-01

367

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

368

Manganese uptake and Mn(II) oxidation by the alga Scenedesmus subspicatus  

Microsoft Academic Search

To examine the relationships among manganese concentration in the culture medium, algae growth, manganese uptake and Mn(II) oxidation on the algal surface, we exposed the unicellular alga Scenedesmus subspicatus to a broad range of free Mn2+ ion concentrations. Extra- and intracellular manganese concentrations were distinguished by reducing the Mn oxides with ascorbate. A large fraction of the Mn bound by

Katja Knauer; Thomas Jabusch; Laura Sigg

1999-01-01

369

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

PubMed Central

Summary 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. Mn2+?derived higher oxidation states of Mn (Mn3+, Mn4+) by Mn2+?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. Mn2+?dependent degradation of EE2 was found to be a slow process, which requires multi?fold excess of Mn2+ 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.

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

2008-01-01

370

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

PubMed

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

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

2010-01-01

371

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

372

The Discrimination between Magnesium and Manganese by Serum Proteins  

PubMed Central

Magnesium and manganese have proved physically and functionally interchangeable in many isolated biological systems investigated in vitro. This lack of discrimination contrasts sharply with the high biological specificity exhibited by intact mammals under a large variety of conditions. The dichotomy between intact animals and their isolated systems might be due at least partially to presence vs. absence of an intact circulation. Hence the capability of mammalian plasma to discriminate between the alkaline earth and the transition metal was investigated by means of equilibrium dialysis, exchange, ultrafiltration, ultracentrifugation, and zone electrophoresis. The states of the respective elements are thus contrasted as follows: (a) Magnesium is partially bound, manganese totally. (b) Magnesium is nonselectively bound by serum proteins, manganese selectively by a ?1-globulin. (c) Under conditions approaching physiological, the two metals do not interchange. This is interpreted as indicating that the plasma proteins contribute to biological specificity by discriminating between a trace metal and a macronutrient.

Foradori, A. C.; Bertinchamps, Albert; Gulibon, Jane M.; Cotzias, George C.

1967-01-01

373

Risk assessment of an essential element: manganese.  

PubMed

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

Santamaria, Annette B; Sulsky, Sandra I

2010-01-01

374

Manganese Transport via the Transferrin Mechanism  

PubMed Central

Excessive manganese (Mn) uptake by brain cells, particularly in regions like the basal ganglia, can lead to toxicity. Mn2+ is transported into cells via a number of mechanisms, while Mn3+ is believed to be transported similarly to iron (Fe) via the transferrin (Tf) mechanism. Cellular Mn uptake is therefore determined by the activity of the mechanisms transporting Mn into each type of cell and by the amounts of Mn2+, Mn3+ and their complexes to which these cells are exposed; this complicates understanding the contributions of each transporter to Mn toxicity. While uptake of Fe3+ via the Tf mechanism is well understood, uptake of Mn3+ via this mechanism has not been systematically studied. The stability of the Mn3+Tf complex allowed us to form and purify this complex and label it with a fluorescent (Alexa green) tag. Using purified and labeled Mn3+Tf and biophysical tools, we have developed a novel approach to study Mn3+Tf transport independently of other Mn transport mechanisms. This approach was used to compare the uptake of Mn3+Tf into neuronal cell lines with published descriptions of Fe3+ uptake via the Tf mechanism, and to obtain quantitative information on Mn uptake via the Tf mechanism. Results confirm that in these cell lines significant Mn3+ is transported by the Tf mechanism similarly to Fe3+Tf transport; although Mn3+Tf transport is markedly slower than other Mn transport mechanisms. This novel approach may prove useful for studying Mn toxicity in other systems and cell types.

Gunter, Thomas E.; Gerstner, Brent; Gunter, Karlene K.; Malecki, Jon; Gelein, Robert; Valentine, William M.; Aschner, Michael; Yule, David I.

2013-01-01

375

Manganese and Iron Oxidation During Benthic Oxygenic Photosynthesis  

NASA Astrophysics Data System (ADS)

The effect of benthic oxygenic photosynthesis on sediment-water fluxes of manganese and iron was studied for an intertidal sediment. Undisturbed sediments were incubated at an incident surface irradiance of 250 ?E m -2 s -1at 26 °C. Oxygenic photosynthesis was selectively inhibited by adding [3-(3,4-dichloro)-1,1-dimethyl-urea] (DCMU). Benthic fluxes were determined experimentally from the change in manganese and iron concentrations in the overlying water, and were predicted from the pore water concentration gradients at the sediment-water interface assuming molecular diffusion as the transport mechanism. The experimental fluxes of manganese and iron in DCMU-treated cores amounted to -0·84 and -0·59 mmol m -2day -1, respectively, and were directed from the sediment towards the overlying water. In the control cores, showing high rates of benthic oxygenic photosynthesis, the fluxes of manganese and iron were directed towards the sediment, 0·06 and 0·01 mmol m -2day -1, respectively. Mass balances for the 0·1-0·14 cm thick oxic zone, calculated from the experimental fluxes and the predicted fluxes, suggest a minimum areal reoxidation of 0·6 mmol m -2day -1for manganese and of 0·48 mmol m -2day -1for iron in cores showing benthic photosynthesis. The estimated turnover times for dissolved Mn 2+and dissolved Fe 2+in the oxic surface layer during benthic photosynthesis were 0·8 and 0·25 h, respectively. Sediment oxygen microprofiles and the sediment pH profiles suggest that chemical precipitation and reoxidation dominates the retention of manganese and iron during benthic oxygenic photosynthesis in shallow intertidal sediments.

Epping, E. H. G.; Schoemann, V.; de Heij, H.

1998-12-01

376

Supporting steel  

SciTech Connect

The US Department of Energy (DOE) and the American Iron and Steel Institute (AISI) have just completed a pilot program on the technical and economic viability of direct ironmaking by a process based on bath smelting. In this process, oxygen, prereduced iron ore pellets, coal, and flux are charged into a molten slag bath containing a high percentage of carbon. The carbon removes oxygen from the iron ore and generates carbon monoxide and liquid iron. Oxygen is then injected to burn some of the carbon monoxide gas before it leaves the smelting vessel. The partially combusted gas is sued to preheat and prereduced the ore before it is injected into the bath. There are several competing cokeless ironmaking processes in various stages of development around the world. A brief comparison of these processes provides a useful perspective with which to gauge the progress and objectives of the AISI-DOE research initiative. The principal competing foreign technologies include the Corex process, DIOS, HIsmelt, and Jupiter. The advantages of the direct ironmaking process examined by AISI-DOE were not sufficiently demonstrated to justify commercialization without further research. However, enough knowledge was gained from laboratory and pilot testing to teach researchers how to optimize the direct ironmaking process and to provide the foundation for future research. Researchers now better understand issues such as the dissolution of materials, reduction mechanisms and rates, slag foaming and control, the behavior of sulfur, dust generation, and the entire question of energy efficiency--including post combustion and the role of coal/volatile matter.

Badra, C. [International Trade Commission, Washington, DC (United States)

1995-10-01

377

Manganese neurotoxicity: a review of clinical features, imaging and pathology.  

PubMed

Manganese intoxication can result in a syndrome of parkinsonism and dystonia. If these extrapyramidal findings are present, they are likely to be irreversible and even progress after termination of the exposure to manganese. Clinical features are usually sufficient to distinguish these patients from those with Parkinson's disease. The neurological syndrome does not respond to levodopa. Imaging of the brain may reveal MRI signal changes in the globus pallidus, striatum, and midbrain. Positron emission tomography reveals normal presynaptic and postsynaptic nigrostriatal dopaminergic function. The primary site of neurological damage has been shown by pathological studies to be the globus pallidus. The mechanism of toxicity is not clear. PMID:10385886

Pal, P K; Samii, A; Calne, D B

1999-01-01

378

Manganese-Induced Parkinsonism due to Ephedrone Abuse  

PubMed Central

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

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

2011-01-01

379

Ultrahigh Carbon Steel.  

National Technical Information Service (NTIS)

Recent studies and results on ultrahigh carbon (UHC) steels would 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 develo...

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

1984-01-01

380

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

381

Production and characterisation of titanium doped electrolytic manganese dioxide for use in rechargeable alkaline zinc/manganese dioxide batteries  

NASA Astrophysics Data System (ADS)

A preliminary screening test of some organo-titanium compounds was conducted. The aim was to find their chemical stability in the electrolyte used for manganese dioxide production. Titanium doped electrolytic manganese dioxide (Ti-EMD) samples were prepared using suitable organo-titanium compounds and a special fine-grained titanium dioxide. The Ti-EMD samples were characterised by conducting physical, chemical and electrochemical tests on them. Physical tests included: X-ray diffraction analysis and BET surface area determination. Chemical test conducted was the determination of titanium content of samples. The electrochemical characterisation involved: cyclic voltammetry, galvanostatic discharge and application of sample in real cell situations. Doped samples performed well in comparison with TOSOH-Hellas GH-S (commercial battery grade electrolytic manganese dioxide).

Nartey, V. K.; Binder, L.; Huber, A.

382

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

383

Coating newly galvanized steel  

SciTech Connect

Galvanize steel may be coated to decorate the piece or to enhance the protection afforded by the galvanizing. However, these coating often fail because pretreatment and coating applications were performed as if steel, not zinc, was being coated. This article explains how galvanizing protects steel, how organic coating can protect or reinforce galvanizing, and how to pretreat and coat newly galvanized steel for optimal corrosion resistance.

Byrnes, G.

1995-10-01

384

SOME EFFECTS OBSERVED BY ELECTRON SPIN RESONANCE OF THE DIFFUSION OF MANGANESE INTO THE CALCIUM AND STRONTIUM FLUORIDE LATTICES  

Microsoft Academic Search

The x-band electron spin resonance spectra of calcium or strontium ; fluoride powder mechanically mixed with manganese fluoride, manganese ammonium ; fluoride, or manganese dioxide powder were observed immediately after nofixing, ; after periods of time, and after heating at various temperatures in an argon ; stream or in air. The proportion of manganese to calcium or strontium was 0.5%.

G. F. J. Garlick; A. Cunliffe; M. N. Jones

1962-01-01

385

Manganese sulfide formation via concomitant microbial manganese oxide and thiosulfate reduction  

SciTech Connect

The dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1 produced {gamma}-MnS (rambergite) nanoparticles during the concurrent reduction of MnO{sub 2} and thiosulfate coupled to H{sub 2} oxidation. To investigate effect of direct microbial reduction of MnO{sub 2} on MnS formation, two MR-1 mutants defective in outer membrane c-type cytochromes ({Delta}mtrC/{Delta}omcA and {Delta}mtrC/{Delta}omcA/{Delta}mtrF) were also used and it was determined that direct reduction of MnO{sub 2} was dominant relative to chemical reduction by biogenic sulfide generated from thiosulfate reduction. Although bicarbonate was excluded from the medium, incubations of strain MR-1 with lactate as the electron donor produced MnCO{sub 3} (rhodochrosite) as well as MnS in nearly equivalent amounts as estimated by micro X-ray diffraction (micro-XRD) analysis. It was concluded that carbonate released from lactate metabolism promoted MnCO{sub 3} formation and that Mn(II) mineralogy was strongly affected by carbonate ions even in the presence of abundant sulfide and weakly alkaline conditions expected to favor the precipitation of MnS. Formation of MnS, as determined by a combination of micro-XRD, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction analyses was consistent with equilibrium speciation modeling predictions. Biogenic manganese sulfide may be a manganese sink in the Mn biogeochemical cycle in select environments such as deep anoxic marine basins within the Baltic Sea.

Lee, Ji-Hoon; Kennedy, David W.; Dohnalkova, Alice; Moore, Dean A.; Nachimuthu, Ponnusamy; Reed, Samantha B.; Fredrickson, Jim K.

2011-12-13

386

VACUUM FLOW STEEL DEGASSING  

Microsoft Academic Search

A steel degassing technique developed and used by the Henrichschutte ; steel plant in Germany's Ehr is described. The process, reportedly capable of ; reduci Hâ, Nâ, and Oâ contents of all types of steels to those ; levels obtalned by vacuum casting techniques, require from 12 to 15 min in a 6O ; to 80-ton ladle. The metal i

Starratt

1958-01-01

387

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

388

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

389

Effects of heat treatment and alloying elements on the microstructures and mechanical properties of 0.15 wt pct C transformation-induced plasticity-aided cold-rolled steel sheets  

Microsoft Academic Search

The main emphasis of this study has been placed on understanding the effects of manganese and silicon additions and of heat-treatment\\u000a (intercritical annealing and isothermal treatment) conditions on the microstructures and mechanical properties of 0.15 wt\\u000a pct C transformation-induced plasticity (TRIP)-aided cold-rolled steel sheets. The steel sheets were intercritically annealed\\u000a and isothermally treated at the bainitic region. Microstructural observation and

Sung-Joon Kim; Chang Gjl Lee; Ildong Choi; Sunghak Lee

2001-01-01

390

The Overlapping Roles of Manganese and Cu/Zn SOD in Oxidative Stress Protection  

PubMed Central

In various organisms, high intracellular manganese provides protection against oxidative damage through unknown pathways. Herein we use a genetic approach in S. cerevisiae to analyze factors that promote manganese as an anti-oxidant in cells lacking Cu/Zn superoxide dismutase (sod1?). Unlike certain bacterial systems [1], oxygen resistance in yeast correlates with high intracellular manganese without a lowering of iron. This manganese for anti-oxidant protection is provided by the Nramp transporters Smf1p and Smf2p, with Smf1p playing a major role. In fact, loss of manganese transport by Smf1p together with loss of the Pmr1p manganese pump is lethal to sod1? cells in spite of normal manganese SOD2 activity. Manganese-phosphate complexes are excellent superoxide dimustase mimics in vitro [2], yet through genetic disruption of phosphate transport and storage, we observed no requirement for phosphate in manganese suppression of oxidative damage. If anything, elevated phosphate correlated with profound oxidative stress in sod1? mutants. The efficacy of manganese as an anti-oxidant was drastically reduced in cells that hyper-accumulate phosphate without effects on MnSOD activity. Non-SOD manganese can provide a critical backup for Cu/Zn SOD1, but only under appropriate physiologic conditions.

Reddi, Amit R.; Jensen, Laran T.; Naranuntarat, Amornrat; Rosenfeld, Leah; Leung, Edison; Shah, Rishita; Culotta, Valeria C.

2009-01-01

391

The overlapping roles of manganese and Cu/Zn SOD in oxidative stress protection.  

PubMed

In various organisms, high intracellular manganese provides protection against oxidative damage through unknown pathways. Herein we use a genetic approach in Saccharomyces cerevisiae to analyze factors that promote manganese as an antioxidant in cells lacking Cu/Zn superoxide dismutase (sod1 Delta). Unlike certain bacterial systems, oxygen resistance in yeast correlates with high intracellular manganese without a lowering of iron. This manganese for antioxidant protection is provided by the Nramp transporters Smf1p and Smf2p, with Smf1p playing a major role. In fact, loss of manganese transport by Smf1p together with loss of the Pmr1p manganese pump is lethal to sod1 Delta cells despite normal manganese SOD2 activity. Manganese-phosphate complexes are excellent superoxide dismutase mimics in vitro, yet through genetic disruption of phosphate transport and storage, we observed no requirement for phosphate in manganese suppression of oxidative damage. If anything, elevated phosphate correlated with profound oxidative stress in sod1 Delta mutants. The efficacy of manganese as an antioxidant was drastically reduced in cells that hyperaccumulate phosphate without effects on Mn SOD activity. Non-SOD manganese can provide a critical backup for Cu/Zn SOD1, but only under appropriate physiologic conditions. PMID:18973803

Reddi, Amit R; Jensen, Laran T; Naranuntarat, Amornrat; Rosenfeld, Leah; Leung, Edison; Shah, Rishita; Culotta, Valeria C

2009-01-15

392

Determination of the oxidation states of manganese in brain, liver, and heart mitochondria.  

PubMed

Excess brain manganese can produce toxicity with symptoms that resemble those of Parkinsonism and causes that remain elusive. Manganese accumulates in mitochondria, a major source of superoxide, which can oxidize Mn2+ to the powerful oxidizing agent Mn3+. Oxidation of important cell components by Mn3+ has been suggested as a cause of the toxic effects of manganese. Determining the oxidation states of intramitochondrial manganese could help to identify the dominant mechanism of manganese toxicity. Using X-ray absorbance near edge structure (XANES) spectroscopy, we have characterized the oxidation state of manganese in mitochondria isolated from brain, liver, and heart over concentrations ranging from physiological to pathological. Results showed that (i) spectra from different model manganese complexes of the same oxidation state were similar to each other and different from those of other oxidation states and that the position of the absorption edge increases with oxidation state; (ii) spectra from intramitochondrial manganese in isolated brain, heart and liver mitochondria were virtually identical; and (iii) under these conditions intramitochondrial manganese exists primarily as a combination of Mn2+ complexes. No evidence for Mn3+ was detected in samples containing more than endogenous manganese levels, even after incubation under conditions promoting reactive oxygen species (ROS) production. While the presence of Mn3+ complexes cannot be proven in the spectrum of endogenous mitochondrial manganese, the shape of this spectrum could suggest the presence of Mn3+ near the limit of detection, probably as MnSOD. PMID:14690515

Gunter, Thomas E; Miller, Lisa M; Gavin, Claire E; Eliseev, Roman; Salter, Jason; Buntinas, Linas; Alexandrov, Andrei; Hammond, Sean; Gunter, Karlene K

2004-01-01

393

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

SciTech Connect

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

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

1980-11-01

394

Fatigue Isotropy in Cross-Rolled, Hardened Isotropic-Quality Steel  

NASA Astrophysics Data System (ADS)

Deformation and forging operations often introduce microstructural orientation and, therewith, mechanical anisotropy to steel. Flattened manganese sulfide inclusions are held responsible for a great part of fatigue anisotropy. Isotropic-quality (IQ) steel maintains the mechanical isotropy of the material, even after a deformation operation. Isotropic material generally contains little S and, therewith, few manganese sulfides. Further, the IQ steels used in this investigation were Ca treated. The Ca treatment improves the shape stability of the sulfides, even during a hot-working deformation. Two commercial materials were compared for their fatigue response, a standard medium-carbon steel with 0.04 wt pct S and a low-sulfur variant that underwent IQ treatment. The two batches were cross-rolled to plates with a deformation ratio of 4.5, leading to in-plane isotropy. Tension-compression fatigue testing was performed in longitudinal and short transversal directions relative to the rolling plane. The results showed strong anisotropy of the fatigue behavior for the standard material. The performance in the short transverse direction, with the principal stress perpendicular to the flattened inclusions, was inferior. The IQ material with nearly spherical inclusions was almost perfectly isotropic, with only slightly worse fatigue response in the short transverse direction.

Temmel, C.; Karlsson, B.; Ingesten, N.-G.

2008-05-01

395

Local control of magnetic damping in ferromagnetic/non-magnetic bilayers by interfacial intermixing induced by focused ion-beam irradiation  

NASA Astrophysics Data System (ADS)

The influence of interfacial intermixing on the picosecond magnetization dynamics of ferromagnetic/non-magnetic thin-film bilayers was studied. Low-dose focused-ion-beam irradiation was used to induce intermixing across the interface between a 10 nm Ni81Fe19 layer and a 2-3 nm capping layer of either Au or Cr. Time-resolved magneto-optical Kerr effect was used to study magnetization dynamics as a function of ion-beam dose. With an Au cap, the damping of the un-irradiated bilayer was comparable with native Ni81Fe19 and increased with increasing ion dose. In contrast, for Ni81Fe19/Cr the damping was higher than that for native Ni81Fe19, but the damping decreased with increasing dose.

King, J. A.; Ganguly, A.; Burn, D. M.; Pal, S.; Sallabank, E. A.; Hase, T. P. A.; Hindmarch, A. T.; Barman, A.; Atkinson, D.

2014-06-01

396

Performance characterization of magnesium\\/manganese dioxide batteries  

Microsoft Academic Search

The effects of storage and temperature on the performance of magnesium\\/manganese dioxide batteries produced by two different manufacturers was studied. Both batteries performed extremely poorly at -17 C (0 F), losing over 70 percent capacity, compared with performance at 21 C (70 F) and above. After partial usage, and storage, both battery types lost as much as 25 hours of

Louis Jarvis

1991-01-01

397

Deformation and texture of copper–manganese alloys  

Microsoft Academic Search

Manganese is the only element that can be dissolved in copper up to 12% without markedly changing the stacking fault energy (SFE). Hence, investigation of the deformation behaviour of Cu–Mn alloys may yield insight into the influence of alloying elements apart from the (usual) decrease in SFE. The development of the crystallographic texture is analysed in various Cu–Mn alloys that

O. Engler

2000-01-01

398

Ag-Cu-Mn (Silver-Copper-Manganese)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume C3 'Non-Ferrous Metal Systems. Part 3: Selected Soldering and Brazing Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Silver-Copper-Manganese.

Materials Science International Team MSIT

399

Ag-Cu-Mn (Silver-Copper-Manganese)  

Microsoft Academic Search

This document is part of Subvolume C3 'Non-Ferrous Metal Systems. Part 3: Selected Soldering and Brazing Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Silver-Copper-Manganese.

2007-01-01

400

Role of trichomes in sunflower tolerance to manganese toxicity  

Microsoft Academic Search

Summary In comparison with other crop species, sunflower (Helianthus annuus L.) has been found to be very tolerant of high manganese (Mn) concentrations in nutrient solution. Furthermore, sunflower was able to accumulate high Mn concentrations in plant tops without apparent detrimental effect on growth. The first symptom of excess Mn supply (c. 30?M Mn in solution) was the appearance of

F. P. C. Blamey; D. C. Joyce; D. G. Edwards; C. J. Asher

1986-01-01

401

Manganese–nitrogen–sulphur surface layers produced on aluminium alloys  

Microsoft Academic Search

The main reason of the surface modification of the components such as pistons and cylinder blocks made of cast aluminium alloys is to obtain high hardness, wear and corrosion resistance of the working surface for larger lifetime of the motor-car and aircraft engines. In that aspect, the new conception of creating — by hybrid method — surface layers containing manganese,

W. Serbi?ski

2005-01-01

402

Joint Electrolytic Deposition of Vanadium and Manganese Oxides  

Microsoft Academic Search

The electrolysis conditions and the character of the anodic processes were studied at the joint anodic deposition of vanadium and manganese oxides from mixed sulfate solutions in the form of double oxide systems, which are promising cathode materials of lithium batteries.

V. M. Nagirnyi; R. D. Apostolova; A. S. Baskevich; P. M. Litvin

2002-01-01

403

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

404

Cognitive Function Related to Environmental Exposure to Manganese  

EPA Science Inventory

Background: The towns of Marietta and East Liverpool (EL), Ohio, have been identified as having elevated manganese (Mn) in air due to industrial pollution. Objectives: To evaluate relationships between environmental Mn (Mn-air) exposure and distance from the source and cognitive...

405

Elements of the iron and manganese cycles in Lake Baikal  

USGS Publications Warehouse

Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time of renewal, etc.). Some previous results and common concepts were critically reevaluated. ?? Pleiades Publishing, Ltd. 2007.

Granina, L. Z.; Callender, E.

2007-01-01

406

Diagnosis and correction of manganese deficiency in corn  

Microsoft Academic Search

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

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

1984-01-01

407

Aqueous ferrofluids based on manganese and cobalt ferrites  

Microsoft Academic Search

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

Francisco Augusto Tourinho; Raymonde Franck; René Massart

1990-01-01

408

Surfactant manganese complexes as models for the oxidation of water  

SciTech Connect

Surfactant manganese complexes have been studied spectroscopically and electrochemically as models for the catalysts involved in the photooxidation of water to produce oxygen. Evidence has been obtained for the participation of the suggested redox cycle Mn/sup II/ to Mn/sup III/ to Mn/sup IV/ and back to Mn/sup II/ with the evolution of oxygen.

Wohlgemuth, R.; Otvos, J.W.; Calvin, M.

1984-02-01

409

Manganese and iron oxidation by fungi isolated from building stone  

Microsoft Academic Search

Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was

M. A. Torre; G. Gomez-Alarcon

1994-01-01

410

Authigenic todorokite and phillipsite inside deep-sea manganese nodules  

Microsoft Academic Search

Phillipsite and todorokite assemblages are observed by scanning electron microscopy to line cavities and voids adjacent to areas where extensive leaching of biogenic siliceous debris has occurred inside deep-sea manganese nodules. Clusters of todorokite crystallites containing Ni and Cu also fill fissures, coat biogenic debris, and infill voids where biogenic debris once occurred in interiors of the nodules. We suggest

VlncrNn Mrn; BunNs tuo RocsR; G. BunNs

411

MANGANESE TOXICOKINETICS AT THE BLOOD-BRAIN BARRIER  

EPA Science Inventory

Investigators expect to study the mechanisms by which manganese enters and leaves the brain across the blood–brain barrier and, in particular, whether transporter molecules are involved. The investigators plan to use in vivo brain perfusion in rats as well as in vitro...

412

Buckwheat as a dietary source of zinc, copper and manganese  

Microsoft Academic Search

The contents of zinc, copper and manganese in various samples of buckwheat were analysed. There was a variation in the contents of the trace elements among various buckwheat samples examined. In addition, a statistically significant positive correlation between these trace elements in buckwheat samples was observed. Chromatographic analysis indicated that there were some soluble components of zinc and copper in

Sayoko IKEDA; Yoshiko YAMASHITA

413

RICE PLANT STRUCTURAL CHANGES BY ADDITION OF EXCESS MANGANESE  

Microsoft Academic Search

Manganese (Mn) has not been considered to be a polluting metal, however soil conditions often present in acid and volcanic soils can lead to Mn reduction favoring Mn toxicity in natural and agricultural systems. As this problem has particular importance in rice paddy fields, with the aim of gaining fundamental insights into rice tolerance to Mn excess, the structural changes

Fernando C. Lidon

2002-01-01

414

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 ...

415

Manganese chloride stimulates rat microglia to release hydrogen peroxide  

PubMed Central

Elevated exposure to manganese is known to cause neurodegeneration in the basal ganglia and to induce movement abnormalities called manganism. However, the underlying mechanism of action is not fully understood. Activation of the resident immune cells in the brain, microglia that release a variety of neurotoxic factors, has been implicated to contribute to neurodegeneration. Of the various neurotoxic factors released by activated microglia, reactive oxygen species such as superoxide and hydrogen peroxide are particularly detrimental to the survival of the oxidative damage-prone neurons. In this study, we report that exposure of rat microglia to manganese chloride (MnCl2) resulted in a time- and concentration-dependent release of hydrogen peroxide (H2O2). The MnCl2-stimulated microglial H2O2 release was sensitive to inhibitors of mitogen-activated protein kinases (MAPK) but not that of NADPH oxidase. MnCl2 induced a rapid activation of the extracellular signal-regulated kinase (ERK) and p38-MAPK in microglia that appeared to precede the MnCl2-induced H2O2 release, suggesting that ERK and p38-MAPK influenced the MnCl2-induced H2O2 release in microglia. In summary, these results demonstrate that manganese chloride is capable of activating microglia to release ROS and MAPK may, in part, be key regulators of the process. These findings may shed significant light on the potential role of microglia in the manganese-induced neurotoxicity.

Zhang, Ping; Hatter, Angela; Liu, Bin

2007-01-01

416

Manganese chloride stimulates rat microglia to release hydrogen peroxide.  

PubMed

Elevated exposure to manganese is known to cause neurodegeneration in the basal ganglia and to induce movement abnormalities called manganism. However, the underlying mechanism of action is not fully understood. Activation of the resident immune cells in the brain, microglia that release a variety of neurotoxic factors, has been implicated to contribute to neurodegeneration. Of the various neurotoxic factors released by activated microglia, reactive oxygen species such as superoxide and hydrogen peroxide are particularly detrimental to the survival of the oxidative damage-prone neurons. In this study, we report that exposure of rat microglia to manganese chloride (MnCl(2)) resulted in a time- and concentration-dependent release of hydrogen peroxide (H(2)O(2)). The MnCl(2)-stimulated microglial H(2)O(2) release was sensitive to inhibitors of mitogen-activated protein kinases (MAPK) but not that of NADPH oxidase. MnCl(2)-induced a rapid activation of the extracellular signal-regulated kinase (ERK) and p38-MAPK in microglia that appeared to precede the MnCl(2)-induced H(2)O(2) release, suggesting that ERK and p38-MAPK influenced the MnCl(2)-induced H(2)O(2) release in microglia. In summary, these results demonstrate that manganese chloride is capable of activating microglia to release ROS and MAPK may, in part, be key regulators of the process. These findings may shed significant light on the potential role of microglia in the manganese-induced neurotoxicity. PMID:17669604

Zhang, Ping; Hatter, Angela; Liu, Bin

2007-09-10

417

Manganese oxide nanocomposites with improved surface area prepared by one-pot surfactant route for electro catalytic and biosensor applications  

Microsoft Academic Search

Braunite phase manganese oxide is naturally available in manganese–silicate rocks with minor amount of silicate content. New\\u000a synthetic route is attempted to prepare the manganese oxide nanoparticle and silica incorporated manganese oxide nanocomposite\\u000a in the present study. XRD patterns reveal the braunite phase formation for as synthesized manganese oxide nanocomposite and\\u000a silica incorporated MnO2 nanocomposite materials. Improved BET surface area

R. Jothiramalingam; M. K. Wang

2010-01-01

418

Stress and strain-induced formation of martensite and its effects on strength and ductility of metastable austenitic stainless steels  

Microsoft Academic Search

The effects of deformation-induced formation of martensite have been studied in metastable austenitic stainless steels. The\\u000a stability of the austenite, being the critical factor in the formation of martensite, was controlled principally by varying\\u000a the amounts of carbon and manganese. The formation of martensite was also affected by different test and rolling temperatures,\\u000a rolling time, and various reductions in thickness.

Dieter Fahr

1971-01-01

419

Microstructure and mechanical properties of Fe–0.2C–5Mn steel processed by ART-annealing  

Microsoft Academic Search

Microstructure and mechanical properties of medium manganese steel (Fe–0.2C–5Mn) processed by annealing at 650°C with annealing time up to 12h after accelerated cooling were studied. It was found that the martensite structure was gradually transformed into a superfine ferrite and austenite duplex structure by austenite reverted transformation during annealing process. The annealing heat treatment results in a large volume fraction

W. Q. Cao; C. Wang; J. Shi; M. Q. Wang; W. J. Hui; H. Dong

2011-01-01

420

The steel scrap age.  

PubMed

Steel production accounts for 25% of industrial carbon emissions. Long-term forecasts of steel demand and scrap supply are needed to develop strategies for how the steel industry could respond to industrialization and urbanization in the developing world while simultaneously reducing its environmental impact, and in particular, its carbon footprint. We developed a dynamic stock model to estimate future final demand for steel and the available scrap for 10 world regions. Based on evidence from developed countries, we assumed that per capita in-use stocks will saturate eventually. We determined the response of the entire steel cycle to stock saturation, in particular the future split between primary and secondary steel production. During the 21st century, steel demand may peak in the developed world, China, the Middle East, Latin America, and India. As China completes its industrialization, global primary steel production may peak between 2020 and 2030 and decline thereafter. We developed a capacity model to show how extensive trade of finished steel could prolong the lifetime of the Chinese steelmaking assets. Secondary steel production will more than double by 2050, and it may surpass primary production between 2050 and 2060: the late 21st century can become the steel scrap age. PMID:23442209

Pauliuk, Stefan; Milford, Rachel L; Müller, Daniel B; Allwood, Julian M

2013-04-01

421

Prenatal exposure to manganese in South African coastal communities.  

PubMed

Exposure to environmental sources and altered physiological processes of manganese uptake during pregnancy and its possible effect on prenatal and postnatal development are of concern. This study investigates manganese blood levels at the time of delivery across four cohorts of pregnant women residing in coastal communities of South Africa and examines birth outcomes and environmental factors that could influence manganese levels in the study population. The geometric mean (GM) manganese blood levels (MnB) for all women at delivery was 15.2 ?g L(-1). Collectively, rural women reported higher MnB concentrations (GM, 16.1 ?g L(-1)) than urban women (GM, 13.5 ?g L(-1), p < 0.001). Of the 302 cord blood samples drawn from the study participants (rural women only), GM MnB levels reported for three rural sites were 25.8 ?g L(-1) (Rural 1), 33.4 ?g L(-1) (Rural 2) and 43.0 ?g L(-1) (Rural 3) and were twice as high as their respective maternal levels. However, no significant correlations were found between maternal and cord MnB levels across the 3 study areas. Factors associated with elevated maternal MnB levels, after adjusting for gestational age were: women living in a rural area (Rural 2) (p = 0.021); women drinking potable water from an outdoor/communal tap sourced from municipality (p = 0.021); drinking water from river/stream (p = 0.036); younger maternal age (p = 0.026); consuming leafy vegetables once a week (p = 0.034); and elevated maternal blood lead concentrations (PbB) (p = 0.002). The results indicate that MnB concentration in rural women during pregnancy is higher compared to urban women and increases with manganese intake from food and water. PMID:24912024

Röllin, Halina B; Kootbodien, Tahira; Theodorou, Penny; Odland, Jon Ø

2014-07-23

422

Associations of welding and manganese exposure with Parkinson disease  

PubMed Central

Objective: To examine associations of welding and manganese exposure with Parkinson disease (PD) using meta-analyses of data from cohort, case-control, and mortality studies. Methods: Epidemiologic studies related to welding or manganese exposure and PD were identified in a PubMed search, article references, published reviews, and abstracts. Inclusion criteria were 1) cohort, case-control, or mortality study with relative risk (RR), odds ratio (OR), or mortality OR (MOR) and 95 confidence intervals (95% CI); 2) RR, OR, and MOR matched or adjusted for age and sex; 3) valid study design and analysis. When participants of a study were a subgroup of those in a larger study, only results of the larger study were included to assure independence of datasets. Pooled RR/OR estimates and 95% CIs were obtained using random effects models; heterogeneity of study effects were evaluated using the Q statistic and I2 index in fixed effect models. Results: Thirteen studies met inclusion criteria for the welding meta-analysis and 3 studies for the manganese exposure meta-analysis. The pooled RR for the association between welding and PD for all study designs was 0.86 (95% CI 0.80–0.92), with absence of between-study heterogeneity (I2 = 0.0). Effect measures for cohort, case-control, and mortality studies were similar (0.91, 0.82, 0.87). For the association between manganese exposure and PD, the pooled OR was 0.76 (95% CI 0.41–1.42). Conclusions: Welding and manganese exposure are not associated with increased PD risk. Possible explanations for the inverse association between welding and PD include confounding by smoking, healthy worker effect, and hormesis.

Borenstein, Amy R.; Nelson, Lorene M.

2012-01-01

423

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The primary major deposit of manganese in the US which can be readily mined by an in situ process is located in the Emily district of Minnesota. The US Bureau of Mines Research Centers at both the Twin Cities and Salt Lake City have developed a process for extracting and refining manganese in the form of a high-purity carbonate product. This product has been formulated into pellets by a multi-step process of drying, calcination, and induration to produce relatively high-strength formulations which are capable of being used for hot fuel gas desulfurization. These pellets, which have been developed at the University of Minnesota under joint sponsorship of the US Department of Energy and the US Bureau of Mines, appear superior to other, more expensive, formulations of zinc titanate and zinc ferrite which have previously been studied for multi-cycle loading (desulfurization) and regeneration (evolution of high-strength SO{sub 2} and restoration of pellet reactivity). Although these other formulations have been under development for the past twelve years, their prices still exceed $7 per pound. If manganese pellets perform as predicted in fixed bed testing, and if a significant number of utilities which burn high-sulfur coals incorporate combined-cycle gasification with hot coal gas desulfurization as a viable means of increasing conversion efficiencies, then the potential market for manganese pellets may be as high as 200,000 tons per year at a price not less than $3 per pound. This paper discusses the role of manganese pellets in the desulfurization process with respect to the integrated gasification combined-cycle (IGCC) for power generation.

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

1995-11-01

424

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

425

Characterization of copper precipitation in a 17/4 PH steel: A combined APFIM/TEM study  

SciTech Connect

A combined atom probe field ion microscopy and transmission electron microscopy characterization of a commercial 17/4 PH steel has been performed. The steel was examined after thermal aging for various times at 482 and 635{degrees}C. The good mechanical properties of this material are derived from the precipitation of small copper precipitates during thermal aging. Atom probe microanalysis of these copper precipitates revealed that they contained small but significant levels of iron, nickel and manganese even in the overaged condition. Chromium-enriched {alpha}{prime} precipitates were observed after aging at 482{degrees}C. 5 refs., 10 figs., 3 tabs.

Miller, M.K. (Oak Ridge National Lab., TN (USA)); Burke, M.G. (Westinghouse Electric Corp., Pittsburgh, PA (USA). Science and Technology Center)

1991-01-01

426

Development of a High-Strength High-Manganese Stainless Steel for Cryogenic Use.  

National Technical Information Service (NTIS)

Structural materials for the superconducting magnets of fusion reactors must exhibit very high strength and toughness at cryogenic temperatures, as represented by a yield strength of over 1,200 MPa and KIC value of more than 200-MPa (square root of m) at ...

K. Suemune K. Sugino H. Masumoto S. Shimamoto H. Nakajima

1986-01-01

427

Bionics growth mechanism of nodular eutectic in as-cast manganese steel  

Microsoft Academic Search

It is well known that all substances in the universe exist stably in the lowest energy state, and a ball of substance with the same volume reveals the lowest surface energy. Therefore, without the interference of external factors, many plants grow freely into the nodular form from a nucleus, such as a peach or a plum. It is also found

Q. C. Jiang; Qingfeng Guan; Yuguang Zhao; Zhenming Xu; Shuqi Wang; Yuqian Zhao; Fujie Rong; Zhenming He

2001-01-01

428

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

429

Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium  

NASA Astrophysics Data System (ADS)

The possible roles of siderophores (high affinity chelators of iron(III)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVD MnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVD MnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350-600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVD MnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A max = 408-410 nm) different from that of either PVD MnB1-Fe(III) or uncomplexed PVD MnB1. Mn(III) competed strongly with Fe(III) for binding by PVD MnB1 in culture filtrates (pH 8, 4°C). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVD MnB1 complex at a citrate/PVD MnB1 molar ratio of 830 (pH 8, 4°C), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVD MnB1 complex. Most of the PVD MnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVD MnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4°C) for the neutral species MnHPVD MnB1 (log K = 47.5 ± 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVD MnB1 (log K = 44.6 ± 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron.

Parker, Dorothy L.; Sposito, Garrison; Tebo, Bradley M.

2004-12-01

430

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

431

Manganese Exposure is Cytotoxic and Alters Dopaminergic and GABAergic Neurons within the Basal Ganglia  

PubMed Central

Manganese is an essential nutrient, integral to proper metabolism of amino acids, proteins and lipids. Excessive environmental exposure to manganese can produce extrapyramidal symptoms similar to those observed in Parkinson’s disease (PD). We used in vivo and in vitro models to examine cellular and circuitry alterations induced by manganese exposure. Primary mesencephalic cultures were treated with 10–00µM manganese chloride (MnCl2) which resulted in dramatic changes in the neuronal cytoskeleton even at subtoxic concentrations. Using cultures from mice with red fluorescent protein (RFP) driven by the tyrosine hydroxylase (TH) promoter, we found that dopaminergic neurons were more susceptible to manganese toxicity. To understand the vulnerability of dopaminergic cells to chronic manganese exposure, mice were given IP injections of MnCl2 for 30 days. We observed a 20% reduction in TH-positive neurons in the substantia nigra pars compacta (SNpc) following manganese treatment. Quantification of Nissl bodies revealed a widespread reduction in SNpc cell numbers. Other areas of the basal ganglia were also altered by manganese as evidenced by the loss of GAD67 in the striatum. These studies suggest that acute manganese exposure induces cytoskeletal dysfunction prior to degeneration and that chronic manganese exposure results in neurochemical dysfunction with overlapping features to PD.

Stanwood, Gregg D.; Leitch, Duncan B.; Savchenko, Valentina; Wu, Jane; Fitsanakis, Vanessa A.; Anderson, Douglas J.; Stankowski, Jeannette N.; Aschner, Michael; McLaughlin, BethAnn

2009-01-01

432

Electrochemical concepts and techniques in the study of stainless steel ennoblement.  

PubMed

Electrochemical theory and technique used to investigate microbially influenced corrosion is discussed with a focus on methods used to demonstrate the manganic-oxide mechanism of stainless steel Ennoblement. The concept of mixed potential and its relationship to the current-voltage behavior of stainless steel is developed. This concept is used to interpret microbially induced changes in corrosion potential, polarization behavior, surface-oxide abundance, and the redox environment at submerged metal surfaces. Microelectrode, capacitance, and coulometric methods are described that can be used to discriminate electrochemical effects caused by changes in solution properties from those caused by mineral deposition at the metal surface. The variety of electrochemical, wet-chemical, microbiological, and surface analytical techniques used to demonstrate the effect of biomineralized manganese dioxide on the electrochemical behavior of stainless steel are summarized. PMID:9807801

Dickinson, W H; Lewandowski, Z

1998-01-01

433

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

434

Taurine improves the spatial learning and memory ability impaired by sub-chronic manganese exposure  

PubMed Central

Background Excessive manganese exposure induced cognitive deficit. Several lines of evidence have demonstrated that taurine improves cognitive impairment induced by numerous neurotoxins. However, the role of taurine on manganese-induced damages in learning and memory is still elusive. This goal of this study was to investigate the beneficial effect of taurine on learning and memory capacity impairment by manganese exposure in an animal model. Results The escape latency in the Morris Water Maze test was significantly longer in the rats injected with manganese than that in the rats received both taurine and manganese. Similarly, the probe trial showed that the annulus crossings were significantly greater in the taurine plus manganese treated rats than those in the manganese-treated rats. However, the blood level of manganese was not altered by the taurine treatment. Interestingly, the exposure of manganese led to a significant increase in the acetylcholinesterase activity and an evidently decrease in the choline acetyltransferase activity, which were partially restored by the addition of taurine. Additionally, we identified 9 differentially expressed proteins between the rat hippocampus treated by manganese and the control or the manganese plus taurine in the proteomic analysis using the 2-dimensional gel electrophoresis followed by the tandem mass spectrometry (MS/MS). Most of these proteins play a role in energy metabolism, oxidative stress, inflammation, and neuron synapse. Conclusions In summary, taurine restores the activity of AChE and ChAT, which are critical for the regulation of acetylcholine. We have identified seven differentially expressed proteins specifically induced by manganese and two proteins induced by taurine from the rat hippocampus. Our results support that taurine improves the impaired learning and memory ability caused by excessive exposure of manganese.

2014-01-01

435

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

436

Nano-sized manganese oxide: a proposed catalyst for water oxidation in the reaction of some manganese complexes and cerium(IV) ammonium nitrate.  

PubMed

According to UV-visible spectroscopy, X-ray diffraction spectrometry, dynamic light scattering, Fourier transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy, nano-sized manganese oxides are proposed as active catalysts for water oxidation in the reaction of some manganese complexes and cerium(IV) ammonium nitrate. PMID:22806229

Najafpour, Mohammad Mahdi; Moghaddam, Atefeh Nemati

2012-09-14

437

Comparative evaluation of oxidative stress status and manganese availability in plants growing on manganese mine.  

PubMed

This study pioneered an approach that determined the effects of excess manganese (Mn) on three species; Datura stramonium, Alhagi camelthorn and Chenopodium ambrosioides. We investigated their levels of Mn, antioxidative enzymes and oxidative damage biomarkers in plants (zone 1) in and outside (zone 2) the Mn mine. The results showed that total and available Mn were at toxic levels for plants growing on zone 1. The Mn levels in each plant species were higher in leaves, stems and roots. Mn was only accumulated significantly in leaf vacuoles of A. camelthorn. Antioxidative enzyme activities of C. ambrosioides and/or D. stramonium in zone 1 were higher in leaves, stems and then in their roots. Malondialdehyde (MDA) and dityrosine levels were insignificantly higher in tissues of the studied plants in zone 1 with respect to zone 2. The roots of studied plants showed significantly higher levels of these biomarkers in comparison with their leaves in zone 1. Accordingly, antioxidative enzymatic response to Mn-stress in D. stramonium and C. ambrosioides and possibly accumulation of Mn in leaf vacuoles of A. camelthorn, protected them from oxidative damages and involved in their tolerance in Mn mine. PMID:18068229

Boojar, Massod Mashhadi Akbar; Goodarzi, Faranak

2008-11-01

438

Arsenite oxidation by a poorly-crystalline manganese oxide. 3. Arsenic and manganese desorption.  

PubMed

Arsenic (As) mobility in the environment is greatly affected by its oxidation state and the degree to which it is sorbed on metal oxide surfaces. Manganese oxides (Mn oxides) have the ability to decrease overall As mobility both by oxidizing toxic arsenite (As(III)) to less toxic arsenate (As(V)), and by sorbing As. However, the effect of competing ions on the mobility of As sorbed on Mn-oxide surfaces is not well understood. In this study, desorption of As(V) and As(III) from a poorly crystalline phyllomanganate (?-MnO(2)) by two environmentally significant ions is investigated using a stirred-flow technique and X-ray absorption spectroscopy (XAS). As(III) is not observed in solution after desorption under any conditions used in this study, agreeing with previous studies showing As sorbed on Mn-oxides exists only as As(V). However, some As(V) is desorbed from the ?-MnO(2) surface under all conditions studied, while neither desorptive used in this study completely removes As(V) from the ?-MnO(2) surface. PMID:21950706

Lafferty, Brandon J; Ginder-Vogel, Matthew; Sparks, Donald L

2011-11-01

439

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide  

NASA Astrophysics Data System (ADS)

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) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 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) 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.

Balistrieri, Laurie S.; Chao, T. T.

1990-03-01

440

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

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