Syntheses, structures, and magnetic properties of three new MnII-[MoIII(CN)7]4- molecular magnets.

PubMed

Wei, Xiao-Qin; Pi, Qian; Shen, Fu-Xing; Shao, Dong; Wei, Hai-Yan; Wang, Xin-Yi

2018-05-22

By reaction of K4[MoIII(CN)7]·2H2O, Mn(ClO4)2·6H2O and bidentate chelating ligands, three new cyano-bridged compounds, namely Mn2(3-pypz)(H2O)(CH3CN)[Mo(CN)7] (1), Mn2(1-pypz)(H2O)(CH3CN)[Mo(CN)7] (2) and Mn2(pyim)(H2O)(CH3CN)[Mo(CN)7] (3) (3-pypz = 2-(1H-pyrazol-3-yl)pyridine, 1-pypz = 2-(1H-pyrazol-1-yl)pyridine, pyim = 2-(1H-imidazol-2-yl)pyridine), have been synthesized and characterized structurally and magnetically. Single crystal X-ray analyses revealed that although the chelating ligands are different, compounds 1 to 3 are isomorphous and crystallize in the same monoclinic space group C2/m. Connected by the bridging cyano groups, one crystallographically unique [Mo(CN)7]4- unit and three crystallographically unique MnII ions of different coordination environments form similar three-dimensional frameworks, which have a four-nodal 3,4,4,7-connecting topological net with a vertex symbol of {43}{44·62}2{410·611}. Magnetic measurements revealed that compounds 1-3 display long-range magnetic ordering with critical temperatures of 64, 66 and 62 K, respectively. These compounds are rare examples of a small number of chelating co-ligand coordinated [Mo(CN)7]4--based magnetic materials. Specifically, the bidentate chelating ligands were successfully introduced into the heptacyanomolybdate system for the first time.

Manganism in the 21st century: the Hanninen lecture.

PubMed

Racette, Brad A

2014-12-01

Since the original description of the health effects of inhaled occupational manganese (Mn) by Couper in 1837, an extensive literature details the clinical syndrome and pathophysiology of what was thought to be a rare condition. In the last decade, conventional wisdom regarding the clinicopathological effects of Mn has been challenged. Past exposures to Mn were an order of magnitude higher than modern exposures in developed countries; therefore, the clinical syndrome seen in the time of Couper is no longer typical of modern Mn exposed workers. Parkinsonism (rigidity, bradykinesia, rest tremor, and postural instability) is present in 15% of Mn-exposed workers in welding industries, and these parkinsonian signs are associated with reduced health status and quality of life. These parkinsonian signs also overlap considerably with the clinical findings seen in early stages of Parkinson's disease (PD); although, molecular imaging suggests that Mn-exposed workers have dopaminergic dysfunction in a pattern unique from PD. Furthermore, geographic information system studies demonstrate that regions of the US with high industrial Mn emissions have an increased incidence of PD and increased PD associated mortality. This review will contrast historical, descriptive human studies in Mn-exposed subjects with more recent data and will suggest a research agenda for the 21st century. Copyright © 2013 Elsevier Inc. All rights reserved.

Manganese uptake and distribution in the brain after methyl bromide-induced lesions in the olfactory epithelia.

PubMed

Thompson, Khristy J; Molina, Ramon M; Donaghey, Thomas; Savaliya, Sandeep; Schwob, James E; Brain, Joseph D

2011-03-01

Manganese (Mn) is an essential nutrient with potential neurotoxic effects. Mn deposited in the nose is apparently transported to the brain through anterograde axonal transport, bypassing the blood-brain barrier. However, the role of the olfactory epithelial cells in Mn transport from the nasal cavity to the blood and brain is not well understood. We utilized the methyl bromide (MeBr) lesion model wherein the olfactory epithelium fully regenerates in a time-dependent and cell type-specific manner over the course of 6-8 weeks postinjury. We instilled (54)MnCl(2) intranasally at different recovery periods to study the role of specific olfactory epithelial cell types in Mn transport. (54)MnCl(2) was instilled at 2, 4, 7, 21, and 56 days post-MeBr treatment. (54)Mn concentrations in the blood were measured over the first 4-h period and in the brain and other tissues at 7 days postinstillation. Age-matched control rats were similarly studied at 2 and 56 days. Blood and tissue (54)Mn levels were reduced initially but returned to control values by day 7 post-MeBr exposure, coinciding with the reestablishment of sustentacular cells. Brain (54)Mn levels also decreased but returned to control levels only by 21 days, the period near the completion of neuronal regeneration/bulbar reinnervation. Our data show that Mn transport to the blood and brain temporally correlated with olfactory epithelial regeneration post-MeBr injury. We conclude that (1) sustentacular cells are necessary for Mn transport to the blood and (2) intact axonal projections are required for Mn transport from the nasal cavity to the olfactory bulb and brain.

Manganese Uptake and Distribution in the Brain after Methyl Bromide-Induced Lesions in the Olfactory Epithelia

PubMed Central

Thompson, Khristy J.; Molina, Ramon M.; Donaghey, Thomas; Savaliya, Sandeep; Schwob, James E.; Brain, Joseph D.

2011-01-01

Manganese (Mn) is an essential nutrient with potential neurotoxic effects. Mn deposited in the nose is apparently transported to the brain through anterograde axonal transport, bypassing the blood-brain barrier. However, the role of the olfactory epithelial cells in Mn transport from the nasal cavity to the blood and brain is not well understood. We utilized the methyl bromide (MeBr) lesion model wherein the olfactory epithelium fully regenerates in a time-dependent and cell type–specific manner over the course of 6–8 weeks postinjury. We instilled 54MnCl2 intranasally at different recovery periods to study the role of specific olfactory epithelial cell types in Mn transport. 54MnCl2 was instilled at 2, 4, 7, 21, and 56 days post-MeBr treatment. 54Mn concentrations in the blood were measured over the first 4-h period and in the brain and other tissues at 7 days postinstillation. Age-matched control rats were similarly studied at 2 and 56 days. Blood and tissue 54Mn levels were reduced initially but returned to control values by day 7 post-MeBr exposure, coinciding with the reestablishment of sustentacular cells. Brain 54Mn levels also decreased but returned to control levels only by 21 days, the period near the completion of neuronal regeneration/bulbar reinnervation. Our data show that Mn transport to the blood and brain temporally correlated with olfactory epithelial regeneration post-MeBr injury. We conclude that (1) sustentacular cells are necessary for Mn transport to the blood and (2) intact axonal projections are required for Mn transport from the nasal cavity to the olfactory bulb and brain. PMID:21177252

Magnetic, Optical and Magneto-optical Properties of Ni2MnGe Alloy Films

NASA Astrophysics Data System (ADS)

Kim, R. J.; Kudryavtsev, Y. V.; Kim, K. W.

2005-03-01

The influence of atomic ordering on the magnetic, the optical and the magneto-optical (MO) properties of Ni2MnGe Heusler alloy (HA) films was investigated. The bulk Ni2MnGe HA was prepared by arc melting, and the films were deposited by flash evaporation onto glass substrates at several substrate temperatures from 150 to 730 K. The bulk Ni2MnGe HA exhibits the cubic L21 structure with a = b = c = 0.5761 nm, and the annealed (at 573 K) bulk alloy is in the tetragonal structure with a = b = 0.5720 nm and c = 0.5865 nm. While the films deposited at 720 K show a well-ordered L21 structure, the deposition at 150 K < T < 710 K results in the formation of a nanocrystalline or an amorphous microstructure. It was found the structural disorder in Ni2MnGe films induces lack of the ferromagnetic order and noticeable changes in the optical and MO response.

The Effects of Helium Bubble Microstructure on Ductility in Annealed and HERF 21Cr-6Ni-9Mn Stainless Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tosten, M.H.; Morgan, M.J.

1998-01-01

This study examined the effects of microstructure on the ambient temperature embrittlement from hydrogen isotopes and decay helium in 21Cr-6Ni-9Mn stainless steel. Hydrogen and tritium-exposed 21Cr-6Ni-9Mn stainless steel tensile samples were pulled to failure and then characterized by transmission electron microscopy (TEM) and optical microscopy. This study determined that ductility differences between annealed and high-energy-rate-forged (HERF) stainless steel containing tritium and its decay product, helium, could be related to differences in the helium bubble microstructures. The HERF microstructures were more resistant to tritium-induced embrittlement than annealed microstructures because the high number density of helium bubbles on dislocations trap tritium withinmore » the matrix and away from the grain boundaries.« less

Three-Dimensional Fibrous Network of Na0.21 MnO2 for Aqueous Sodium-Ion Hybrid Supercapacitors.

PubMed

Karikalan, Natarajan; Karuppiah, Chelladurai; Chen, Shen-Ming; Velmurugan, Murugan; Gnanaprakasam, Periyasami

2017-02-16

Sodium-ion hybrid supercapacitors are potential energy-storage devices and have recently received enormous interest. However, the development of cathode materials and the use of nonaqueous electrolyte remain a great challenge. Hence, aqueous Na-ion hybrid supercapacitors based on a three-dimensional network of NaMnO 2 were developed. The cathode material was synthesized by the electro-oxidation of potassium manganese hexacyanoferrate nanocubes. The oxidized compound was confirmed to be Na 0.21 MnO 2 by various physical characterization methods. Manganese dioxide is a well-characterized material for aqueous asymmetric pseudocapacitors, but its usage at high operating voltages is limited due to the electrochemical stability of water. Nevertheless, high-potential and high-performance aqueous supercapacitors exhibiting a cell potential of 2.7 V were developed. Further, the practical applicability of an asymmetric supercapacitor based on NaMnO 2 (cathode) and reduced graphene oxide (anode) was demonstrated by powering a 2.1 V red LED. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effects of annealing on the microstructure and mechanical properties of Fe 28Ni 18Mn 33Al 21

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Fanling; Qiu, Jingwen; Baker, Ian

In this paper, As-cast Fe 28Ni 18Mn 33Al 21, which consists of aligned, 50 nm, (Ni, Al)-rich B2, and (Fe, Mn)-rich f.c.c. phases, was annealed at a variety of temperatures up to 1423 K and the microstructure and mechanical properties were examined. It was shown that the as-cast microstructure arises from a eutectoid transformation at ~1300 K. Annealing at temperatures ≤1073 K produces β-Mn-structured precipitates and hardness values up to 816 HV, while annealing at temperatures >1073 K leads to dramatic coarsening of the two-phase B2/f.c.c. microstructure (up to 5.5 µm after 50 h at 1273 K), but does notmore » lead to β-Mn precipitation. Interestingly, annealing at temperatures >1073 K delays the onset of β-Mn precipitation during subsequent anneals at lower temperatures. Coarsening the B2/f.c.c. lamellar structure by annealing at higher temperatures softens it and leads to increases in ductility from fracture before yield to ~8 % elongation. Finally, the presence of β-Mn precipitates makes the very fine, brittle B2/f.c.c. microstructures even more brittle, but significant ductility (8.4 % elongation) is possible even with β-Mn precipitates present if the B2/f.c.c. matrix is coarse and, hence, more ductile.« less

Suppression of Magnetic Quantum Tunneling in a Chiral Single-Molecule Magnet by Ferromagnetic Interactions.

PubMed

Lippert, Kai-Alexander; Mukherjee, Chandan; Broschinski, Jan-Philipp; Lippert, Yvonne; Walleck, Stephan; Stammler, Anja; Bögge, Hartmut; Schnack, Jürgen; Glaser, Thorsten

2017-12-18

Single-molecule magnets (SMMs) retain a magnetization without applied magnetic field for a decent time due to an energy barrier U for spin-reversal. Despite the success to increase U, the difficult to control magnetic quantum tunneling often leads to a decreased effective barrier U eff and a fast relaxation. Here, we demonstrate the influence of the exchange coupling on the tunneling probability in two heptanuclear SMMs hosting the same spin-system with the same high spin ground state S t = 21/2. A chirality-induced symmetry reduction leads to a switch of the Mn III -Mn III exchange from antiferromagnetic in the achiral SMM [Mn III 6 Cr III ] 3+ to ferromagnetic in the new chiral SMM RR [Mn III 6 Cr III ] 3+ . Multispin Hamiltonian analysis by full-matrix diagonalization demonstrates that the ferromagnetic interactions in RR [Mn III 6 Cr III ] 3+ enforce a well-defined S t = 21/2 ground state with substantially less mixing of M S substates in contrast to [Mn III 6 Cr III ] 3+ and no tunneling pathways below the top of the energy barrier. This is experimentally verified as U eff is smaller than the calculated energy barrier U in [Mn III 6 Cr III ] 3+ due to tunneling pathways, whereas U eff equals U in RR [Mn III 6 Cr III ] 3+ demonstrating the absence of quantum tunneling.

The effects of annealing on the microstructure and mechanical properties of Fe 28Ni 18Mn 33Al 21

DOE PAGES

Meng, Fanling; Qiu, Jingwen; Baker, Ian; ...

2015-08-20

In this paper, As-cast Fe 28Ni 18Mn 33Al 21, which consists of aligned, 50 nm, (Ni, Al)-rich B2, and (Fe, Mn)-rich f.c.c. phases, was annealed at a variety of temperatures up to 1423 K and the microstructure and mechanical properties were examined. It was shown that the as-cast microstructure arises from a eutectoid transformation at ~1300 K. Annealing at temperatures ≤1073 K produces β-Mn-structured precipitates and hardness values up to 816 HV, while annealing at temperatures >1073 K leads to dramatic coarsening of the two-phase B2/f.c.c. microstructure (up to 5.5 µm after 50 h at 1273 K), but does notmore » lead to β-Mn precipitation. Interestingly, annealing at temperatures >1073 K delays the onset of β-Mn precipitation during subsequent anneals at lower temperatures. Coarsening the B2/f.c.c. lamellar structure by annealing at higher temperatures softens it and leads to increases in ductility from fracture before yield to ~8 % elongation. Finally, the presence of β-Mn precipitates makes the very fine, brittle B2/f.c.c. microstructures even more brittle, but significant ductility (8.4 % elongation) is possible even with β-Mn precipitates present if the B2/f.c.c. matrix is coarse and, hence, more ductile.« less

Role of magnetic and atomic ordering in the martensitic transformation of Ni-Mn-In from a first-principles study

NASA Astrophysics Data System (ADS)

Li, Chun-Mei; Luo, Hu-Bin; Hu, Qing-Miao; Yang, Rui; Johansson, Börje; Vitos, Levente

2012-12-01

The composition-dependent lattice parameters, crystal structure, elastic properties, magnetic moment, and electronic structure of Ni2Mn1+xIn1-x (0≤x≤0.6) are studied by using first-principles calculations. It is shown that the martensitic phase transition (MPT) from cubic L21 to tetragonal L10 accompanies the MnMn-MnIn ferromagnetic (FM) to antiferromagnetic (AFM) transition, at around the critical composition x=0.32, in agreement with the experimental measurement. The Mn-In atomic disorder leads to decreasing stability of the martensite relative to the austenite, which depresses the MPT. The shear elastic constant C' of the parent phase first decreases slightly with increasing x and then remains almost unchanged above x=0.32, indicating C' alone cannot account for the increase of the MPT temperature with x. The total magnetic moments for the L21 phase are in good agreement with those determined by experiments, whereas for the L10 phase they are slightly larger than the experimental data due to the possible Mn-In atomic disorder in the sample. The calculated density of states demonstrate that the covalent bonding between the minority spin states of Ni and In plays an important role in both the magnetic and structural stability.

[μ-10,21-Dimethyl-3,6,14,17-tetra-za-tricyclo-[17.3.1.1]tetra-cosa-1(23),2,6,8,10,12 (24),13,17,19,21-deca-ene-23,24-diolato-κN,N,O,O:κN,N,O,O]bis-(perchlorato-κO)dimanganese(II).

PubMed

Liu, Jing; Pan, Zhi-Quan; Zhou, Hong; Li, Yi-Zhi

2008-11-08

In the centrosymmetric and dinuclear title complex, [Mn(2)(C(22)H(22)N(4)O(2))(ClO(4))(2)], the two Mn atoms are bridged by two phenolate O atoms of the N(4)O(2) macrocycle with an Mn⋯Mn distance of 2.9228 (11) Å. The distorted square-pyramidal N(2)O(3) coordination geometry is completed by an O atom derived from a perchlorate anion.

Electronic interaction in an outer-sphere mixed-valence double salt: a polarized neutron diffraction study of K(3)(MnO(4))(2).

PubMed

Cannon, Roderick D; Jayasooriya, Upali A; Tilford, Claire; Anson, Christopher E; Sowrey, Frank E; Rosseinsky, David R; Stride, John A; Tasset, Francis; Ressouche, Eric; White, Ross P; Ballou, Rafik

2004-11-01

The mixed-valence double salt K(3)(MnO(4))(2) crystallizes in space group P2(1)/m with Z = 2. The manganese centers Mn1 and Mn2 constitute discrete "permanganate", [Mn(VII)O(4)](-), and "manganate", [Mn(VI)O(4)](2-), ions, respectively. There is a spin-ordering transition to an antiferromagnetic state at ca. T = 5 K. The spin-density distribution in the paramagnetic phase at T = 10 K has been determined by polarized neutron diffraction, confirming that unpaired spin is largely confined to the nominal manganate ion Mn2. Through use of both Fourier refinement and maximum entropy methods, the spin on Mn1 is estimated as 1.75 +/- 1% of one unpaired electron with an upper limit of 2.5%.

Laser weldability of 21Cr-6Ni-9Mn stainless steel: Part II - Weldability diagrams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tate, Stephen B.; Javernick, Daniel Anthony; Lienert, Thomas J.

In this second part of the study, weldability diagrams developed to relate solidification crack susceptibility and chemical composition for laser welded type 21Cr-6Ni-9Mn (21-6-9) stainless steel are presented. Sigmajig testing on 14 commercial 21-6-9 alloys, 20 experimental 21-6-9 alloys, and 7 other high-N, high-Mn austenitic stainless steels was used to develop weldability diagrams for solidification crack susceptibility for laser welding of type 21-6-9. Three travel speeds were used to show the changes in minimum Cr eq/Ni eq for primary ferrite solidification as solidification rate increase d with travel speed . Primary austenite solidification was observed below 1.55 Cr eq/Ni eqmore » (Espy equivalents) at 21 mm/s travel speed. At 42 mm/s travel speed , a mix of solidification modes were displayed for alloys from 1.55-1.75 Cr eq/Ni eq. Primary ferrite solidification was observed above 1.75 Cr eq/Ni eq at both 42 and 85 mm/s travel speeds. No solidification cracking was observed for alloys with primary ferrite solidification. Lastly, variable cracking behavior was found in alloys with primary austenite solidification, but in general cracking was observed in alloys with greater than 0.02 wt-% combined impurity content according to (P+0.2S).« less

Laser weldability of 21Cr-6Ni-9Mn stainless steel: Part II - Weldability diagrams

DOE PAGES

Tate, Stephen B.; Javernick, Daniel Anthony; Lienert, Thomas J.; ...

2016-11-02

In this second part of the study, weldability diagrams developed to relate solidification crack susceptibility and chemical composition for laser welded type 21Cr-6Ni-9Mn (21-6-9) stainless steel are presented. Sigmajig testing on 14 commercial 21-6-9 alloys, 20 experimental 21-6-9 alloys, and 7 other high-N, high-Mn austenitic stainless steels was used to develop weldability diagrams for solidification crack susceptibility for laser welding of type 21-6-9. Three travel speeds were used to show the changes in minimum Cr eq/Ni eq for primary ferrite solidification as solidification rate increase d with travel speed . Primary austenite solidification was observed below 1.55 Cr eq/Ni eqmore » (Espy equivalents) at 21 mm/s travel speed. At 42 mm/s travel speed , a mix of solidification modes were displayed for alloys from 1.55-1.75 Cr eq/Ni eq. Primary ferrite solidification was observed above 1.75 Cr eq/Ni eq at both 42 and 85 mm/s travel speeds. No solidification cracking was observed for alloys with primary ferrite solidification. Lastly, variable cracking behavior was found in alloys with primary austenite solidification, but in general cracking was observed in alloys with greater than 0.02 wt-% combined impurity content according to (P+0.2S).« less

Structural and dielectric characteristics of double perovskite La2(NiFe)1/2MnO6

NASA Astrophysics Data System (ADS)

Nasir, Mohd.; Kandasami, Asokan; Sen, Somaditya

2018-05-01

Recently, La2NiMnO6 has drawn significant interest because large magnetic field induced changes in dielectric properties makes this compound a promising material for potential spintronic device applications. In the present study, the structural and dielectric characteristics of sol-gel prepared La2(Ni1/2Fe1/2)MnO6 double perovskite ceramics were evaluated. La2(Ni1/2Fe1/2)MnO6 was crystallized in the monoclinic P21/n structure with ordered Ni2+/Fe2+ and Mn4+ cations. A giant dielectric constant with relaxor-like behavior was observed, which was attributed to the dipolar effects arising from hopping between Ni2+/Fe2+ and Mn4+ ions.

Al{sub 70}Pd{sub 21.5}Mn{sub 8.5}: A quasicrystal showing the de haas-van Alphen effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haanappel, E.G.; Kycia, S.W.; Harmon, B.N.

1995-07-01

We have measured the de Haas-van Alphen effect in the icosahedral quasicrystal Al{sub 70}Pd{sub 21.5}Mn{sub 8.5}. We have found two well-defined frequencies with the magnetic field parallel to a five-fold axis, and two different ones with the field parallel to a two-fold axis. On increasing the temperature, the amplitude of the oscillations substantially decreased, suggesting that the carriers have large masses.

An Inkjet Printed Piezoresistive Back to Back Tactile Sensor for Endosurgical Palpation Applications (Postprint)

DTIC Science & Technology

2017-02-23

elements linked back-to- back for force and displacement detection, respectively. Experimental results indicate the sensor registers 2.1 and 5.3 mN force...feedback from the fat and muscle tissues of pig, respectively, when pressed to the tissues with the same 100 μm displacement . This difference of ∼2.5...back-to-back for force and displacement detection, respectively. Experimental results indicate the sensor registers 2.1 and 5.3 mN force feedback from

Manganese(II) Chloride Alters Nucleotide and Nucleoside Catabolism in Zebrafish (Danio rerio) Adult Brain.

PubMed

Altenhofen, Stefani; Nabinger, Débora Dreher; Pereira, Talita Carneiro Brandão; Leite, Carlos Eduardo; Bogo, Maurício Reis; Bonan, Carla Denise

2018-05-01

ATP and adenosine, the main signaling molecules of purinergic system, are involved in toxicological effects induced by metals. The manganese (Mn) exposure induces several cellular changes, which could interfere with signaling pathways, such as the purinergic system. In this study, we evaluated the effects of exposure to manganese(II) chloride (MnCl 2 ) during 96 h on nucleoside triphosphate diphosphohydrolase (NTPDase), ecto-5'-nucleotidase, and adenosine deaminase (ADA) activities, followed by analyzing the gene expression patterns of NTPDases (entpd1, entpd2a.1, entpd2a.2, entpd2-like, entpd3) and ADA (ADA 1 , ADA 2.1 , ADA 2.2 , ADAasi, ADAL) families in zebrafish brain. In addition, the brain metabolism of nucleotides and nucleosides was evaluated after MnCl 2 exposure. The results showed that MnCl 2 exposure during 96 h inhibited the NTPDase (1.0 and 1.5 mM) and ecto-ADA (0.5, 1.0, and 1.5 mM) activities, further decreasing ADA2.1 expression at all MnCl 2 concentrations analyzed. Purine metabolism was also altered by the action of MnCl 2 . An increased amount of ADP appeared at all MnCl 2 concentrations analyzed; however, AMP and adenosine levels are decreased at the concentrations of 1.0 and 1.5 mM MnCl 2 , whereas decreased inosine (INO) levels were observed at all concentrations tested. The findings of this study demonstrated that MnCl 2 may inhibit NTPDase and ecto-ADA activities, consequently modulating nucleotide and nucleoside levels, which may contribute for the toxicological effects induced by this metal.

Magnetic susceptibility and ground-state zero-field splitting in high-spin mononuclear manganese(III) of inverted N-methylated porphyrin complexes: Mn(2-NCH3NCTPP)Br.

PubMed

Hung, Sheng-Wei; Yang, Fuh-An; Chen, Jyh-Horung; Wang, Shin-Shin; Tung, Jo-Yu

2008-08-18

The crystal structures of diamagnetic dichloro(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-tin(IV) methanol solvate [Sn(2-NCH 3NCTPP)Cl 2.2(0.2MeOH); 6.2(0.2MeOH)] and paramagnetic bromo(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-manganese(III) [Mn(2-NCH 3NCTPP)Br; 5] were determined. The coordination sphere around Sn (4+) in 6.2(0.2MeOH) is described as six-coordinate octahedron ( OC-6) in which the apical site is occupied by two transoid Cl (-) ligands, whereas for the Mn (3+) ion in 5, it is a five-coordinate square pyramid ( SPY-5) in which the unidentate Br (-) ligand occupies the axial site. The g value of 9.19 (or 10.4) measured from the parallel polarization (or perpendicular polarization) of X-band EPR spectra at 4 K is consistent with a high spin mononuclear manganese(III) ( S = 2) in 5. The magnitude of axial ( D) and rhombic ( E) zero-field splitting (ZFS) for the mononuclear Mn(III) in 5 were determined approximately as -2.4 cm (-1) and -0.0013 cm (-1), respectively, by paramagnetic susceptibility measurements and conventional EPR spectroscopy. Owing to weak C(45)-H(45A)...Br(1) hydrogen bonds, the mononuclear Mn(III) neutral molecules of 5 are arranged in a one-dimensional network. A weak Mn(III)...Mn(III) ferromagnetic interaction ( J = 0.56 cm (-1)) operates via a [Mn(1)-C(2)-C(1)-N(4)-C(45)-H(45A)...Br(1)-Mn(1)] superexchange pathway in complex 5.

Detailed relationship between local structure, polarons, and magnetizationfor La1-xCaxMnO3 (0.21≤x≤0.45)

NASA Astrophysics Data System (ADS)

Bridges, F.; Downward, L.; Neumeier, J. J.; Tyson, T. A.

2010-05-01

We present detailed local structure measurements (using the extended x-ray absorption fine structure technique) for the colossal magnetoresistive material La1-xCaxMnO3 (0.21

Manganese dioxide decoration of macroscopic carbon nanotube fibers: From high-performance liquid-based to all-solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Pendashteh, Afshin; Senokos, Evgeny; Palma, Jesus; Anderson, Marc; Vilatela, Juan J.; Marcilla, Rebeca

2017-12-01

Supercapacitors capable of providing high voltage, energy and power density but yet light, low volume occupying, flexible and mechanically robust are highly interesting and demanded for portable applications. Herein, freestanding flexible hybrid electrodes based on MnO2 nanoparticles grown on macroscopic carbon nanotube fibers (CNTf-MnO2) were fabricated, without the need of any metallic current collector. The CNTf, a support with excellent electrical conductivity, mechanical stability, and appropriate pore structure, was homogeneously decorated with porous akhtenskite ɛ-MnO2 nanoparticles produced via electrodeposition in an optimized organic-aqueous mixture. Electrochemical properties of these decorated fibers were evaluated in different electrolytes including a neutral aqueous solution and a pure 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid (PYR14TFSI). This comparison helps discriminate the various contributions to the total capacitance: (surface) Faradaic and non-Faradaic processes, improved wetting by aqueous electrolytes. Accordingly, symmetric supercapacitors with PYR14TFSI led to a high specific energy of 36 Wh· kgMnO2-1 (16 Wh·kg-1 including the weight of CNTf) and real specific power of 17 kW· kgMnO2-1 (7.5 kW kg-1) at 3.0 V with excellent cycling stability. Moreover, flexible all solid-state supercapacitors were fabricated using PYR14TFSI-based polymer electrolyte, exhibiting maximum energy density of 21 Wh·kg-1 and maximum power density of 8 kW kg-1 normalized by total active material.

Investigation of Some Metals in Leaves and Leaf Extracts of Lippia javanica: Its Daily Intake

PubMed Central

Florence, Kunsamala

2017-01-01

Consumption of plant extracts can be a source of essential elements or a route of human exposure to toxicants. Metal concentrations in leaves, leaf brew, and infusion of L. javanica collected from five sites were determined by atomic absorption spectrometry after acid and aqueous extraction. Estimated daily intakes of metals in extracts were compared with recommended dietary allowances. Total metal concentrations in leaves varied with sampling sites (p < 0.05): Mn > Fe > Cu > Cr > Pb for sites SS2–SS5. The highest metal concentrations in leaves were recorded for SS3 (Cu: 15.32 ± 4.53 and Mn: 734.99 ± 105.49), SS5 (Fe: 210.27 ± 17.17), SS2 (Pb: 3.11 ± 0.21), and SS4 (Cr: 4.40 ± 0.75 mg/kg). Leaf infusion appeared to release higher Cu and Mn concentrations in leaves across sites (Cu: 21.65; Mn: 28.01%) than leaf brew (Cu: 11.95; Mn: 19.74%). Lead was not detected in leaf extracts. Estimated dietary intakes of Cr, Cu, Fe, and Mn were below recommended dietary allowances. A 250 ml cup of leaf infusion contributed 0.30–1.18% Cu and 4.46–13.83% Mn to the recommended dietary allowances of these elements per day. Lead did not pose any potential hazard when consumed in tea beverage made from brew and infusion of leaves of L. javanica. PMID:28781598

Anomalously large effects of pressure on electron transfer kinetics in solution: The aqueous manganate(VI)-permanganate(VII) system

NASA Astrophysics Data System (ADS)

Swaddle, T. W.; Spiccia, L.

1986-05-01

The classical Stranks-Hush-Marcus theory of pressure effects on the rates of outer-sphere electron transfer reaction rates in solution underestimates |ΔV ∗| specifically, for the MnO 4/MnO 42- (aq) exchange, ΔV ∗=-21.2 (observed) vs. -6.6 cm3mol-1 (calculated). This discrepancy can best be resolved by conceding that the Mn-Mn separation σ in the transition state is variable and pressure-sensitive in the context of non-adiabatic electron transfer within an ellipsoidal cavity with σ ∼ 550 pm.

Structural and magnetic transition in stainless steel Fe-21Cr-6Ni-9Mn up to 250 GPa

NASA Astrophysics Data System (ADS)

Liu, Lei; Hou, Qi-Yue; Zhang, Yi; Jing, Qiu-Min; Wang, Zhi-Gang; Bi, Yan; Xu, Ji-An; Li, Xiao-Dong; Li, Yan-Chun; Liu, Jing

2015-06-01

Stainless steel Fe-21Cr-6Ni-9Mn (SS 21-6-9), with ˜21% Cr, ˜6% Ni, and ˜9% Mn in weight percentage, has wide applications in extensive fields. In the present study, SS 21-6-9 is compressed up to 250 GPa, and its crystal structures and compressive behaviors are investigated simultaneously using the synchrotron angle-dispersive x-ray diffraction technique. The SS 21-6-9 undergoes a structural phase transition from fcc to hcp structure at ˜12.8 GPa with neglectable volume collapse within the determination error under the quasi-hydrostatic environment. The hcp structure remains stable up to the highest pressure of 250 GPa in the present experiments. The antiferromagnetic-to-nonmagnetic state transition of hcp SS 21-6-9 with the changes of inconspicuous density and structure, is discovered at ˜50 GPa, and revealed by the significant change in c/a ratio. The hcp SS-21-6-9 is compressive anisotropic: it is more compressive in the c-axis direction than in the a-axis direction. Both the equations of states (EOSs) of fcc and hcp SS 21-6-9, which are in accordance with those of fcc and hcp pure irons respectively, are also presented. Furthermore, the c/a ratio of hcp SS 21-6-9 at infinite compression, R∞, is consistent with the values of pure iron and Fe-10Ni alloy. Project supported by the National Natural Science Foundation of China (Grant Nos. U1230201, 11274281, and 11304294), the Industrial Technology Development Program, China (Grant No. 9045140509), and the Funds from the Chinese Academy of Sciences (Grant Nos. KJCX2-SW-N03 and KJCX2-SW-N20).

Simulation of First-Charge Oxygen-Dimerization and Mn-Migration in Li-Rich Layered Oxides xLi 2MnO 3 ·(1 – x )Li MO 2 and Implications for Voltage Fade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benedek, Roy; Iddir, Hakim

The instabilities of Li-rich layered oxide xLi 2MnO 3•(1-x)LiMO 2 (lithium-ion-battery cathode materials) during the first charge are investigated using first-principles dynamical simulation. To complement our earlier simulations for (x = 0.4, M = Ni 0.5Mn 0.5), we address here: pure Li 2MnO 3; small x; M compositions that include Co; a composite with Co spinel: Li 2MnO 3•Li 2M 2O 4; a Li 2MnO 3 slab. Lastly, we discuss how the threshold fraction f of Li 2(1-f)MnO 3 delithiation at which instabilities occur at the surface, fth(surface), differs from that in the bulk, f th(bulk). Approaches to inhibit voltagemore » fade are discussed.« less

Simulation of First-Charge Oxygen-Dimerization and Mn-Migration in Li-Rich Layered Oxides xLi 2MnO 3 ·(1 – x )Li MO 2 and Implications for Voltage Fade

DOE PAGES

Benedek, Roy; Iddir, Hakim

2017-03-08

The instabilities of Li-rich layered oxide xLi 2MnO 3•(1-x)LiMO 2 (lithium-ion-battery cathode materials) during the first charge are investigated using first-principles dynamical simulation. To complement our earlier simulations for (x = 0.4, M = Ni 0.5Mn 0.5), we address here: pure Li 2MnO 3; small x; M compositions that include Co; a composite with Co spinel: Li 2MnO 3•Li 2M 2O 4; a Li 2MnO 3 slab. Lastly, we discuss how the threshold fraction f of Li 2(1-f)MnO 3 delithiation at which instabilities occur at the surface, fth(surface), differs from that in the bulk, f th(bulk). Approaches to inhibit voltagemore » fade are discussed.« less

Two spin-canting textures in the antiferromagnetic phase AF1 of MnWO4 based on the new polar atomistic model in P2

NASA Astrophysics Data System (ADS)

Park, S.-H.; Liu, B.-Q.; Behal, D.; Pedersen, B.; Schneidewind, A.

2018-04-01

The low temperature antiferromagnetic (AF) phase of MnWO4 (the so-called AF1 phase) exhibits different spin-canting configurations at two Mn2+ sublattices of the (3  +  1)-dimensional magnetic structure. The suggested superspace group {{\\boldsymbol P}}2.1^\\prime(α, 1/2, γ)0s is a significant consequence of the polar space group {{\\boldsymbol P}} 2 true for the nuclear structure of MnWO4. Density functional theory calculations showed that its ground state prefers this two spin-canting system. The structural difference between two independent atomic sites for Mn (Mn a , Mn b ) is too small to allow microscopically detectable electric polarisation. However, this hidden intrinsic polar character allows AF1 two commensurately modulated spin-canting textures. This is considered as the prerequisite onset of the improper ferroelectricity enhanced by the helical spin order in the multiferroic phase AF2 of MnWO4.

Carbon Nanotube/Graphene Supercapacitors Containing Manganese Oxide Nanoparticles

DTIC Science & Technology

2012-12-01

for the carbon source since the GO is actually in solution and not merely suspended as the MWCNTs above were. Next, 2 mg of GO and 3.3 mg of MnAc...Results 2 2.1 GO /Manganese Acetate Solution Preparation .................................................................2 2.2 G/MnOx NP Synthesis...Figure 2. SEM image of ball milled MnAc (3 mole %) with multi-wall carbon nanotubes ( MWCNTs ) annealed at 370 °C. The resulting material is rather

Magnetic and conventional shape memory behavior of Mn-Ni-Sn and Mn-Ni-Sn(Fe) alloys

NASA Astrophysics Data System (ADS)

Turabi, A. S.; Lázpita, P.; Sasmaz, M.; Karaca, H. E.; Chernenko, V. A.

2016-05-01

Magnetic and conventional shape memory properties of Mn49Ni42Sn9(at.%) and Mn49Ni39Sn9Fe3(at.%) polycrystalline alloys exhibiting martensitic transformation from ferromagnetic austenite into weakly magnetic martensite are characterized under compressive stress and magnetic field. Magnetization difference between transforming phases drastically increases, while transformation temperature decreases with the addition of Fe. Both Mn49Ni42Sn9 and Mn49Ni39Sn9Fe3 alloys show remarkable superelastic and shape memory properties with recoverable strain of 4% and 3.5% under compression at room temperature, respectively. These characteristics can be counted as extraordinary among the polycrystalline NiMn-based magnetic shape memory alloys. Critical stress for phase transformation was increased by 34 MPa in Mn49Ni39Sn9Fe3 and 21 MPa in Mn49Ni42Sn9 at 9 T, which can be qualitatively understood in terms of thermodynamic Clausius-Clapeyron relationships and in the framework of the suggested physical concept of a volume magnetostress.

Pyroxenoids of pyroxmangite-pyroxferroite series from xenoliths of Bellerberg paleovolcano (Eifel, Germany): Chemical variations and specific features of cation distribution

NASA Astrophysics Data System (ADS)

Shchipalkina, N. V.; Aksenov, S. M.; Chukanov, N. V.; Pekov, I. V.; Rastsvetaeva, R. K.; Schäfer, C.; Ternes, B.; Shüller, W.

2016-11-01

The pyroxferroite and pyroxmangite from xenoliths of aluminous gneisses in the alkaline basalts of Bellerberg paleovulcano (Eifel, Germany) have been studied by electron-probe and X-ray diffraction methods and IR spectroscopy. The parameters of the triclinic unit cells are found to be a = 6.662(1) Å, b = 7.525(1) Å, c = 15.895(2) Å, α = 91.548(3)°, β = 96.258(3)°, and γ = 94.498(3)° for pyroxferroite and a = 6.661(3) Å, b = 7.513(3) Å, c = 15.877(7) Å, α = 91.870(7)°, β = 96.369(7)°, and γ = 94.724(7)° for pyroxmangite; sp. gr. Poverline 1 . The crystallochemical formulas ( Z = 2) are, respectively, M(1-2)(Mn0.5Ca0.4Na0.1)2 M(3-6)(Fe, Mn)4 M7[Mg0.6(Fe, Mn)0.4][Si7O21] and M(1-3)(Mn, Fe)3 M(4-6)[(Fe, Mn)0.7Mg0.3]3 M7[Mg0.5(Fe, Mn)0.5][Si7O21]. For these and previously studied representatives of the pyroxmangite structural type, an analysis of the cation distribution over sites indicates wide isomorphism of Mn2+, Fe2+, and Mg in all cation M(1-7) sites and the preferred incorporation of Ca and Na into large seven-vertex M1O7 and M2O7 polyhedra and Mg into the smallest five-vertex M7O5 polyhedron.

Magnetic and transport properties of Ga-Mn-Co full Heusler alloy

NASA Astrophysics Data System (ADS)

Samanta, Tamalika; Bhobe, P. A.

2018-04-01

We report structural, electrical and magnetic studies of the Ga rich Heusler compound Ga48Mn25Co27. The Ga-Co-Mn compounds have been predicted to be useful candidates for spintronic applications. We found that the Ga48Mn25Co27 compound crystallizes in cubic L21 structure. It shows a very low curie temperature of 88 K and a soft magnetic behavior. We observed an unusual, non-saturating magnetic hysteresis loop where the virgin curve stays out of the loop. The origin of such behavior might lie in the fact that there exist two competing magnetic sub-lattices with different exchange interactions.

New polynuclear manganese clusters from the use of the hydrophobic carboxylate ligand 2,2-dimethylbutyrate.

PubMed

Chakov, Nicole E; Zakharov, Lev N; Rheingold, Arnold L; Abboud, Khalil A; Christou, George

2005-06-27

The syntheses, structures, and magnetic properties are reported of [Mn12O12(O2CPe(t))16(MeOH)4] (4), [Mn6O2(O2CH2)(O2CPe(t))11(HO2CPe(t))2(O2CMe)] (5), [Mn9O6(OH)(CO3)(O2CPe(t))12(H2O)2] (6), and [Mn4O2(O2CPe(t))6(bpy)2] (7, bpy = 2,2'-bipyridine), where Pe(t) = tert-pentyl (Pe(t)CO2H = 2,2-dimethylbutyric acid). These complexes were all prepared from reactions of [Mn12O12(O2CPe(t))16(H2O)4] (3) in CH2Cl2. Complex 4 x 2MeCN crystallizes in the triclinic space group P1 and contains a central [Mn(IV)4O4] cubane core that is surrounded by a nonplanar ring of eight alternating Mn(III) and eight mu3-O(2-) ions. This is only the third Mn12 complex in which the four bound water molecules have been replaced by other ligands, in this case MeOH. Complex 5 x (1/2)CH2Cl2 crystallizes in the monoclinic space group P2(1)/c and contains two [Mn3(mu3-O)]7+ units linked at two of their apexes by two Pe(t)CO2(-) ligands and one mu4-CH2O2(2-) bridge. The complex is a new structural type in Mn chemistry, and also contains only the third example of a gem-diolate unit bridging four metal ions. Complex 6 x H2O x Pe(t)CO2H crystallizes in the orthorhombic space group Cmc2(1) and possesses a [Mn(III)9(mu3-O)6(mu-OH)(mu3-CO3)]12+ core. The molecule contains a mu3-CO3(2-) ion, the first example in a discrete Mn complex. Complex 7 x 2H2O crystallizes in the monoclinic space group P2(1)/c and contains a known [Mn(III)2Mn(II)2(mu3-O)2]6+ core that can be considered as two edge-sharing, triangular [Mn3O] units. Additionally, the synthesis and magnetic properties of a new enneanuclear cluster of formula [Mn9O7(O2CCH2Bu(t))13(THF)2] (8, THF = tetrahydrofuran) are reported. The molecule was obtained by the reaction of [Mn12O12(O2CCH2Bu(t))16(H2O)4] (2) with THF. Complexes 2 and 4 display quasireversible redox couples when examined by cyclic voltammetry in CH2Cl2; oxidations are observed at -0.07 V (2) and -0.21 V (4) vs ferrocene. The magnetic properties of complexes 4-8 have been studied by direct current (DC) and alternating current (AC) magnetic susceptibility techniques. The ground-state spin of 4 was established by magnetization measurements in the 1.80-4.00 K and 0.5-7 T ranges. Fitting of the reduced magnetization data by full matrix diagonalization, incorporating a full powder average and including only axial anisotropy, gave S = 10, g = 2.0(1), and D = -0.39(10) cm(-1). The complex exhibits two frequency-dependent out-of-phase AC susceptibility signals (chi(M)'') indicative of slow magnetization relaxation. An Arrhenius plot obtained from chi(M)'' vs T data gave an effective energy barrier to relaxation (U(eff)) of 62 and 35 K for the slower and faster relaxing species, respectively. These studies suggest that complex 4 is a single-molecule magnet (SMM). DC susceptibility studies on complexes 5-8 display overall antiferromagnetic behavior and indicate ground-state spin values of S < or = 2. AC susceptibility studies at < 10 K confirm these small values and indicate the population of low-lying excited states even at these low temperatures. This supports the small ground-state spin values to be due to spin frustration effects.

Microstructure and microwave magnetic properties of Low-Firing Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrite

NASA Astrophysics Data System (ADS)

Xie, Fei; Jia, Lijun; Shen, Qihang; Qiu, Hua; Zhang, Huaiwu

2018-03-01

Low firing temperature and excellent gyromagnetic properties such as high remanence square ratio and narrow ferromagnetic resonance line width are required for the application in nonreciprocal microwave ferrite devices based on low temperature cofired ceramics (LTCC) technology. In this research, Bi2O3-Li2CO3 mixture was introduced as the sintering agent to lower the sintering temperature of Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrite. The influence of Bi2O3-Li2CO3 mixture upon the phase composition, composite microstructures and gyromagnetic properties of LiZnTiMn ferrite sintered at low temperature has been investigated for LTCC integration applications. With a proper amount of Bi2O3-Li2CO3 mixture, the sintering temperature of LiZnTiMn ferrite successfully reduced to below 900°C from 1100°C without degradation of magnetic properties, meanwhile, both of saturation flux density and remanence square ratio were increased.

Oxidation-etching preparation of MnO2 tubular nanostructures for high-performance supercapacitors.

PubMed

Zhu, Jixin; Shi, Wenhui; Xiao, Ni; Rui, Xianhong; Tan, Huiteng; Lu, Xuehong; Hng, Huey Hoon; Ma, Jan; Yan, Qingyu

2012-05-01

1D hierarchical tubular MnO(2) nanostructures have been prepared through a facile hydrothermal method using carbon nanofibres (CNFs) as sacrificial template. The morphology of MnO(2) nanostructures can be adjusted by changing the reaction time or annealing process. Polycrystalline MnO(2) nanotubes are formed with a short reaction time (e.g., 10 min) while hierarchical tubular MnO(2) nanostructures composed of assembled nanosheets are obtained at longer reaction times (>45 min). The polycrystalline MnO(2) nanotubes can be further converted to porous nanobelts and sponge-like nanowires by annealing in air. Among all the types of MnO(2) nanostructures prepared, tubular MnO(2) nanostructures composed of assembled nanosheets show optimized charge storage performance when tested as supercapacitor electrodes, for example, delivering an power density of 13.33 kW·kg(-1) and a energy density of 21.1 Wh·kg(-1) with a long cycling life over 3000 cycles, which is mainly related to their features of large specific surface area and optimized charge transfer pathway.

Frequencies of occurrence of all human chromosomes in micronuclei from normal and 5-azacytidine-treated lymphocytes as revealed by chromosome painting.

PubMed

Fauth, E; Scherthan, H; Zankl, H

1998-05-01

Chromosome painting with library DNA probes specific for all human chromosomes was used to study the chromosomal content of micronuclei (MN) in normal and 5-azacytidine (5-aza-C)-treated lymphocyte cultures. More than 60,000 normal lymphocytes were screened for associated MN after in situ hybridization. At least 50 MN were scored for each probe. With the exception of chromosomes 12 and 19, which did not occur in MN, all other chromosomes were detected in MN at frequencies varying from 1 to 11.5%. Treatment of lymphocyte cultures with 5-aza-C induced preferential exclusion of chromosomes 1 (34%), 9 (32%) and 16 (20%) material in MN, whereas chromosome 8, 10, 12-15 and 21 material was not detected in MN. The results obtained from normal lymphocytes allow for the first time an estimation of the frequency of occurrence of all chromosomes in spontaneously occurring MN in human cells. Data derived from 5-aza-C-treated lymphocytes are furthermore consistent with the view that undermethylation of heterochromatin may be associated with loss of specific chromosomes at metaphase.

Fracture behavior of neutron-irradiated high-manganese austenitic steels

NASA Astrophysics Data System (ADS)

Yoshida, H.; Miyata, K.; Narui, M.; Kayano, H.

1991-03-01

The instrumented Charpy impact test was applied to study the fracture behavior of high-manganese austenitic steels before and after neutron irradiations. Quarter-size specimens of a commercial high-manganese steel (18% Mn-5% Ni-16% Cr), three reference steels (21% Mn-1% Ni-9% Cr, 20% Mn-1% Ni-11% Cr, 15% Mn-1% Ni-13% Cr) and two model steels (17% Mn-4.5% Si-6.5% Cr, 22% Mn-4.5% Si-6.5% Cr-0.2% N) were used for the impact tests at temperatures between 77 and 523 K. The load-deflection curves showed typical features corresponding to characteristics of the fracture properties. The temperature dependences of fracture energy and failure deflection obtained from the curves clearly demonstrate only small effects up to 2 × 10 23 n/m 2 ( E > 0.1 MeV) and brittleness at room temperature in 17% Mn-Si-Cr steel at 1.6 × 10 25 n/m 2 ( E > 0.1 MeV), while ductility still remains in 22%Mn-Si-Cr steel.

77 FR 2084 - Notice of Inventory Completion: Minnesota Indian Affairs Council, Bemidji, MN

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-13

... individual were removed from site 21-AN-1, Howard Lake, Anoka County, MN, by unknown person(s) and attached... Woodland Tradition. In 1950, L.A. Wilford of the University of Minnesota excavated human remains... the University of Minnesota. In 1999, the human remains were transferred to the MIAC (H355). No known...

Structure and magnetic properties of Co-Ni-Mn alloy coatings (part 2)

NASA Astrophysics Data System (ADS)

Schmidt, V. V.; Zhikhareva, I. G.; Smirnova, N. V.; Shchipanov, V. P.

2018-03-01

Using the method of high-frequency alternating current (HFAC), based on the preliminary model forecasting of the ratio of metal ions in the electrolyte and the phase composition of the coating, Co-Ni-Mn alloy precipitates with the specified magnetic properties are obtained. It is shown that precipitation with a hexagonal close-packed α-Co phase has the highest coercive force. The presence of a free phase in a small amount (2.1 - 2.6% of weight) of Mn increases the ferromagnetic properties of films due to the domain structures with a poorly defecting α-Mn crystal lattice. The adjustable amount of the amorphous Co(OH)2 phase provides the nanostructure dimensions of the crystals.

Occupational exposure to manganese-containing welding fumes and pulmonary function indices among natural gas transmission pipeline welders.

PubMed

Hassani, Hamid; Golbabaei, Farideh; Ghahri, Asghar; Hosseini, Mostafa; Shirkhanloo, Hamid; Dinari, Behnam; Eskandari, Davood; Fallahi, Majid

2012-01-01

The objectives of this study were to evaluate manganese (Mn)-containing welding fumes' exposure, assess urinary Mn as a biomarker for Mn exposure and investigate the correlation of Mn in air, total fumes and urinary Mn with pulmonary function indices in 118 welders and 37 unexposed controls from two regions in Iran, Assaluyeh and Borujen. Air samples were collected on mixed cellulose ester membrane filters in personal air samplers and then analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-AES) (NIOSH Method 7300). For all participants, urine samples were collected during the entire work shift, and Mn in urine was determined by graphite furnace atomic absorption spectroscopy according to NIOSH Method 8310. Spirometric measurements were also done for participants. The maximum exposures to airborne Mn and total fumes were 0.304 ± 0.256 mg/m(3) and 21.52 ± 9.40 mg/m(3), respectively. The urine Mn levels in the various groups ranged between 0.77 to 7.58 μg/l. The correlation between airborne Mn and urinary Mn was significant for total whole participants. Some values of spirometric indices were statistically lower in welders rather than controls. Our results indicate that many welders have been exposed to higher concentrations of Mn-containing welding fumes. Urinary Mn can be used as a biomarker for Mn exposure. There were weak inverse correlations between Mn-containing welding fumes and pulmonary function indices, and the inverse correlation between urinary Mn with forced vital capacities (FVC) and forced expiratory volume in 1 s (FEV1) was significant.

Unsaturated Mn complex decorated hybrid thioarsenates: Syntheses, crystal structures and physical properties

NASA Astrophysics Data System (ADS)

Yue, Cheng-Yang; Lei, Xiao-Wu; Tian, Ya-Wei; Xu, Jing; Bai, Yi-Qun; Wang, Fei; Zhou, Peng-Fei; Liu, Xiao-Fan; Yi, Fei-Yan

2016-03-01

The incorporation of unsaturated [Mn(1,2-dap)]2+, [Mn(1,2-dap)2]2+, [Mn(2,2-bipy)]2+ (1,2-dap=1,2-diaminopropane) complex cations with thioarsenate anions of [AsIIIS3]3- and [AsVS4]3- led to three new hybrid manganese thioarsenates, namely, [Mn(1,2-dap)]2MnAs2S6 (1), [Mn(1,2-dap)2]{[Mn(1,2-dap)]2As2S8} (2) and (NH4)[Mn(2,2-bipy)2]AsS4 (3). In compound 1, the unsaturated [Mn(1,2-dap)]2+ complexes, [MnS4]6- tetrahedra and [AsIIIS3]3- trigonal-pyramids are condensed to form the 1D [Mn(1,2-dap)]2MnAs2S6 chain, whereas compound 2 features 2D layer composed of [Mn(1,2-dap)]2+ and [Mn(1,2-dap)2]2+ complexes as well as [AsVS4]3- tetrahedral units. For compound 3, two [AsVS4]3- anions bridge two [Mn(2,2-bipy)]2+ complex cations into a butterfly like {[Mn(2,2-bipy)]2As2S8}2- anionic unit. Magnetic measurements indicate the ferrimagnetic behavior for compound 1 and antiferromagnetic (AF) behaviors for compounds 2-3. The UV-vis diffuse-reflectance measurements and electronic structural calculations based on density functional theory (DFT) revealed the title compounds belong to semiconductors with band gaps of 2.63, 2.21, and 1.97 eV, respectively. The narrow band-gap of compound 3 led to the efficient and stable photocatalytic degradation activity over organic pollutant than N-doped P25 under visible light irradiation.

Characterization of Mn-resistant endophytic bacteria from Mn-hyperaccumulator Phytolacca americana and their impact on Mn accumulation of hybrid penisetum.

PubMed

Zhang, Wen-Hui; Chen, Wei; He, Lin-Yan; Wang, Qi; Sheng, Xia-Fang

2015-10-01

Three hundred Mn-resistant endophytic bacteria were isolated from the Mn-hyperaccumulator, Phytolacca americana, grown at different levels of Mn (0, 1, and 10mM) stress. Under no Mn stress, 90%, 92%, and 11% of the bacteria produced indole acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, respectively. Under Mn stress, 68-94%, 91-92%, and 21-81% of the bacteria produced IAA, siderophore, and ACC deaminase, respectively. Greater percentages of ACC deaminase-producing bacteria were found in the Mn-treated P. americana. Furthermore, the ratios of IAA- and siderophore-producing bacteria were significantly higher in the Mn treated plant leaves, while the ratio of ACC deaminase-producing bacteria was significantly higher in the Mn treated-roots. Based on 16S rRNA gene sequence analysis, Mn-resistant bacteria were affiliated with 10 genera. In experiments involving hybrid penisetum grown in soils treated with 0 and 1000mgkg(-1) of Mn, inoculation with strain 1Y31 was found to increase the root (ranging from 6.4% to 18.3%) and above-ground tissue (ranging from 19.3% to 70.2%) mass and total Mn uptake of above-ground tissues (64%) compared to the control. Furthermore, inoculation with strain 1Y31 was found to increase the ratio of IAA-producing bacteria in the rhizosphere and bulk soils of hybrid penisetum grown in Mn-added soils. The results showed the effect of Mn stress on the ratio of the plant growth-promoting factor-producing endophytic bacteria of P. americana and highlighted the potential of endophytic bacterium as an inoculum for enhanced phytoremediation of Mn-polluted soils by hybrid penisetum plants. Copyright © 2015 Elsevier Inc. All rights reserved.

Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP

DOE PAGES

Lamichhane, Tej N.; Taufour, Valentin; Masters, Morgan W.; ...

2016-08-29

Here, ZrMnP and HfMnP single crystals are grown by a self-flux growth technique, and structural as well as temperature dependent magnetic and transport properties are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and HfMnP are ferromagnetic with Curie temperatures around 370 K and 320 K, respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined to be 1.9 μ B/f.u. and 2.1 μ B/f.u., respectively, at 50 K. The magnetocaloric effect of ZrMnP in terms of entropy change (Δ S) is estimated to be –6.7 kJ m –3 K –1 around 369 K. The easy axis of magnetizationmore » is [100] for both compounds, with a small anisotropy relative to the [010] axis. At 50 K, the anisotropy field along the [001] axis is ~4.6 T for ZrMnP and ~10 T for HfMnP. Such large magnetic anisotropy is remarkable considering the absence of rare-earth elements in these compounds. The first principle calculation correctly predicts the magnetization and hard axis orientation for both compounds, and predicts the experimental HfMnP anisotropy field within 25%. More importantly, our calculations suggest that the large magnetic anisotropy comes primarily from the Mn atoms, suggesting that similarly large anisotropies may be found in other 3d transition metal compounds.« less

1D and 3D Polymeric Manganese(II) Thiolato Complexes: Synthesis, Structure, and Properties of    ∞3[Mn4(SPh)8] and ∞1[Mn(SMes)2].

PubMed

Eichhöfer, Andreas; Lebedkin, Sergei

2018-01-16

Reactions of [Mn{N(SiMe 3 ) 2 } 2 ] 2 with 2.1 equiv of RSH, R = Ph or Mes = C 6 H 2 -2,4,6-(CH 3 ) 3 , yield compounds of the formal composition "Mn(SR) 2 ". Single-crystal X-ray diffraction reveals that ∞ 1 [Mn(SMes) 2 ] forms one-dimensional chains in the crystal via μ 2 -SMes bridges, whereas ∞ 3 [Mn 4 (SPh) 8 ] comprises a three-dimensional network in which adamantanoid cages composed of four Mn atoms and six μ 2 -bridging SPh ligands are connected in three dimensions by doubly bridging SPh ligands. Thermogravimetric analysis and powder diffractometry indicate an reversible uptake of solvent molecules (tetrahydrofuran) into the channels of ∞ 1 [Mn(SMes) 2 ]. Magnetic measurements reveal antiferromagnetic coupling for both compounds with J = -8.2 cm -1 ( ∞ 1 [Mn(SMes) 2 ]) and -10.0 cm -1 ( ∞ 3 [Mn 4 (SPh) 8 ]), respectively. Their optical absorption and photoluminescence (PL) excitation spectra display characteristic d-d bands of Mn 2+ ions in the visible spectral region. Both compounds emit bright phosphorescence at ∼800 nm at low temperatures (<100 K). However, only ∞ 1 [Mn(SMes) 2 ] retains a moderately intense emission at ambient temperature (with a quantum yield of 1.2%). Similar PL properties are also found for the related selenolate complexes ∞ 1 [Mn(SeR) 2 ] (R = Ph, Mes).

Magnetic proximity effect and shell-ferromagnetism in metastable Ni50Mn45Ga5

NASA Astrophysics Data System (ADS)

Krenke, Thorsten; ćakır, Aslı; Scheibel, Franziska; Acet, Mehmet; Farle, Michael

2016-12-01

The present study on magnetic and structural properties of Ni50Mn45Ga5 confirms that structural metastability is an inherent property of Ni50Mn50-xXx Heusler alloys with X as In, Ga, and Sn. The ternary alloy transforms during temper-annealing into a dual-phase composite alloy. The two phases are identified to be cubic L21, Ni50Mn25Ga25, and tetragonal L10 Ni50Mn50. Depending on the annealing temperature, the magnetic-proximity effect giving rise to shell-ferromagnetism has been observed when annealing is carried out under an external magnetic field. The upper and lower remanence values MR+ and MR- have the same sign even at high temperatures. Such alloys can be promising candidates for heat- and magnetic-field-resistant magnetic recording media.

[Spectroscopic study on the binding of Mn(II) to EHPG].

PubMed

Li, Hai-peng; Zhao, Chun-gui; Li, Xiao-li; Yang, Bin-sheng

2007-02-01

Under the conditions of 0.05 mol x L(-1) Hepes buffer at room temperature and pH 7.4, the interaction of ethylene-N,N'-bis(o-hydroxyphenylglycine) (EHPG) and Mn(II) was investigated by both fluorescence and UV difference spectra. Results showed that the molar ratio of the complex is 1:1. With the addition of manganese ions, the fluorescence peak of EHPG at 310 nm decreased, while the peaks of UV absorptivity at 238 and 291 nm increased. The molar absorptivity of Mn(II) to EHPG at 238 nm is (1.31 +/- 0.02) x 10(4) cm(-1) x mol(-1) L. The disassociation constant for Mn-EHPG was determined to be (1.36 +/- 0.21) x 10(-5). It can be concluded that the binding of Mn(II) to EHPG is not a strongly binding reaction.

Elevated manganese and cognitive performance in school-aged children and their mothers.

PubMed

Menezes-Filho, José A; Novaes, Cristiane de O; Moreira, Josino C; Sarcinelli, Paula N; Mergler, Donna

2011-01-01

Growing evidence suggests that excess manganese (Mn) in children is associated with neurobehavioral impairments. In Brazil, elevated hair Mn concentrations were reported in children living near a ferro-manganese alloy plant. We investigated these children's and caregivers' cognitive function in relation to bioindicators of Mn exposure. In this cross-sectional study, the WISC-III was administered to 83 children aged between 6 and 12 years; the Raven Progressive Matrix was administered to the primary caregivers (94% mothers), who likewise responded to a questionnaire on socio demographics and birth history. Mn in hair (MnH) and blood (MnB) and blood lead (PbB) were measured by graphite furnace atomic absorption spectrometry (GFAAS). Children's mean MnB and MnH were 8.2 μg/L (2.7-23.4) and 5.83 μg/g (0.1-86.68), respectively. Mean maternal MnH was 3.50 μg/g (0.10-77.45) and correlated to children's MnH (rho=0.294, p=0.010). Children's MnH was negatively related to Full-Scale Intelligence Quotient (IQ) and Verbal IQ; β coefficients for MnH were -5.78 (95% CI -10.71 to -0.21) and -6.72 (-11.81 to -0.63), adjusted for maternal education and nutritional status. Maternal MnH was negatively associated with performance on the Raven's (β=-2.69, 95% CI -5.43 to 0.05), adjusted for education years, family income and age. These findings confirm that high MnH in children is associated with poorer cognitive performance, especially in the verbal domain. Primary caregiver's IQ is likewise associated to Mn exposure, suggesting that, in this situation, children's cognition may be affected directly and indirectly by Mn exposure. Copyright © 2010 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menezes-Filho, Jose A., E-mail: antomen@ufba.br; Public and Environmental Health Program, National School of Public Health, Oswaldo Cruz Foundation; Novaes, Cristiane de O.

Background: Growing evidence suggests that excess manganese (Mn) in children is associated with neurobehavioral impairments. In Brazil, elevated hair Mn concentrations were reported in children living near a ferro-manganese alloy plant. Objectives: We investigated these children's and caregivers' cognitive function in relation to bioindicators of Mn exposure. Methods: In this cross-sectional study, the WISC-III was administered to 83 children aged between 6 and 12 years; the Raven Progressive Matrix was administered to the primary caregivers (94% mothers), who likewise responded to a questionnaire on socio demographics and birth history. Mn in hair (MnH) and blood (MnB) and blood lead (PbB)more » were measured by graphite furnace atomic absorption spectrometry (GFAAS). Results: Children's mean MnB and MnH were 8.2 {mu}g/L (2.7-23.4) and 5.83 {mu}g/g (0.1-86.68), respectively. Mean maternal MnH was 3.50 {mu}g/g (0.10-77.45) and correlated to children's MnH (rho=0.294, p=0.010). Children's MnH was negatively related to Full-Scale Intelligence Quotient (IQ) and Verbal IQ; {beta} coefficients for MnH were -5.78 (95% CI -10.71 to -0.21) and -6.72 (-11.81 to -0.63), adjusted for maternal education and nutritional status. Maternal MnH was negatively associated with performance on the Raven's ({beta}=-2.69, 95% CI -5.43 to 0.05), adjusted for education years, family income and age. Conclusions: These findings confirm that high MnH in children is associated with poorer cognitive performance, especially in the verbal domain. Primary caregiver's IQ is likewise associated to Mn exposure, suggesting that, in this situation, children's cognition may be affected directly and indirectly by Mn exposure.« less

Laser weldability of 21Cr-6Ni-9Mn stainless steel: Part I - Impurity effects and solidifcation mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tate, Stephen B.; Javernick, Daniel Anthony; Lienert, Thomas J.

For laser welded type 21Cr-6Ni-9Mn (21-6-9) stainless steels, the relationship between solidification cracking susceptibility and chemical composition was examined, and primary solidification mode (PSM) diagrams were developed to predict solidification mode. Sigmajig testing was used with experimental heats of type 21-6-9 to determine the effect of P and S on solidification cracking w hen primary austenite solidification occurred. Phosphorus showed a larger influence on solidification cracking relative to S, and a relationship of (P+0.2S ) was found for total impurity content. PSM diagrams to predict solidification mode were developed by analyzing welds made at three travel speeds for a widemore » range of 21-6-9 alloys and some other similar alloys. The minimum Cr eq/Ni eq required for primary ferrite solidification increased as travel speed increased, with more alloys showing primary austenite solidification at higher travel rates. Furthermore, as travel speed increased from 21 to 85 mm/s, the average solidification rate increased from 6 to 25 mm/s.« less

Laser weldability of 21Cr-6Ni-9Mn stainless steel: Part I - Impurity effects and solidifcation mode

DOE PAGES

Tate, Stephen B.; Javernick, Daniel Anthony; Lienert, Thomas J.; ...

2016-11-02

For laser welded type 21Cr-6Ni-9Mn (21-6-9) stainless steels, the relationship between solidification cracking susceptibility and chemical composition was examined, and primary solidification mode (PSM) diagrams were developed to predict solidification mode. Sigmajig testing was used with experimental heats of type 21-6-9 to determine the effect of P and S on solidification cracking w hen primary austenite solidification occurred. Phosphorus showed a larger influence on solidification cracking relative to S, and a relationship of (P+0.2S ) was found for total impurity content. PSM diagrams to predict solidification mode were developed by analyzing welds made at three travel speeds for a widemore » range of 21-6-9 alloys and some other similar alloys. The minimum Cr eq/Ni eq required for primary ferrite solidification increased as travel speed increased, with more alloys showing primary austenite solidification at higher travel rates. Furthermore, as travel speed increased from 21 to 85 mm/s, the average solidification rate increased from 6 to 25 mm/s.« less

Higher HOMA-IR index and correlated factors of insulin resistance in patients with IgA nephropathy.

PubMed

Yang, Yue; Wei, Ri-Bao; Wang, Yuan-da; Zhang, Xue-Guang; Rong, Na; Tang, Li; Chen, Xiang-Mei

2012-11-01

To investigate the index of homeostasis model of insulin resistance (HOMA-IR) in IgA nephropathy (IgAN) patients, and to explore the possible correlated factors contributing to insulin resistance (IR) within these patients. There were 255 IgAN patients and 45 membranous nephropathy (MN) patients in our database. We identified 89 IgAN subjects and 21 MN subjects without diabetes and undergoing glucocorticoid therapy for at least 6 months. Data regarding physical examination, blood chemistry and renal pathology were collected from 89 IgAN subjects and 21 MN subjects. Then 62 IgAN patients and 19 MN patients with chronic kidney disease (CKD) Stage 1 - 2 were selected for the comparison of HOMA-IR index, 89 IgAN patients were selected for multiple regression analysis to test for correlated factors of HOMA-IR index with IgAN patients. Comparison between IgAN and MN show that HOMA-IR index was significantly higher in IgAN patients with CKD Stage 1 - 2. After logarithmic transformation with urine protein (UPr), Ln(UPr) (b = 0.186, p = 0.008), eGFR (b = -0.005, p = 0.014), > 50% of glomeruli with mesangial hypercellularity (b = 0.285, p = 0.027) and body mass index (BMI) (b = 0.039, p = 0.008) were correlated factors of HOMA-IR index in the multiple regression analysis. IgAN patients had higher HOMA-IR index compared with MN in the stages of CKD 1 - 2. For IgAN patients, more UPr, lower eGFR, > 50% of glomeruli with mesangial hypercellularity and higher BMI were correlated with IR.

Use of response surface methodology to evaluate the effect of metal ions (Ca2+, Ni2+, Mn2+, Cu2+) on production of antifungal compounds by Paenibacillus polymyxa.

PubMed

Raza, Waseem; Hongsheng, Wu; Qirong, Shen

2010-03-01

The effects of four metal ions (Ca(2+), Ni(2+), Mn(2+) and Cu(2+)) were evaluated on growth and production of antifungal compounds by Paenibacillus polymyxa SQR-21 and a quadratic predictive model was developed using response surface methodology (RSM). The results revealed, Mn(2+) and Ni(2+) showed most positive synergistic interactive affect on production of antifungal compounds followed by the positive interactive synergistic affect of Cu(2+) and Ni(2+) and then Mn(2+) and Cu(2+). While the interactive effect of Ca(2+) with all other three metals inhibited the production of antifungal compounds. The Mn(2+) (P=0.0384), Ni(2+) (P=0.0004) and Cu(2+) (P=0.0117) significantly affected the production of antifungal compounds while the effect of Ca(2+) (P=0.1851) was less significant. The maximum growth (OD(600)=1.55) was obtained at 500 (0), 125 (0), 100 (-2) and 37.5 (0) microM levels and the maximum size of inhibition zone (31 mm) was measured at 400 (-1), 150 (1), 400 (1) and 25 microM (-1) levels of Ca(2+), Mn(2+), Ni(2+) and Cu(2+), respectively. The RSM model provided an easy and effective way to determine the interactive effect of metal ions on production of antifungal compounds by P. polymyxa SQR-21 so that optimum media recipes can be developed to produce maximum amounts of antifungal compounds under laboratory and commercial fermentation conditions. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Tritium and decay helium effects on the fracture toughness properties of types 316L, 304L and 21Cr-6Ni-9Mn stainless steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, M.J.; Tosten, M.H

1994-10-01

J-integral fracture mechanics techniques and electron microscopy observations were used to investigate the effects of tritium and its radioactive decay product, {sup 3}He, on Types 316L, 304L and 21Cr-6Ni-9Mn stainless steels. Tritium-exposed-and-aged steels had lower fracture-toughness values and shallower sloped crack-growth-resistance curves than unexposed steels. Both fracture-toughness parameters decreased with increasing concentrations of {sup 3}He. The fracture-toughness reductions were accompanied by a change in fracture mode from microvoid-nucleation-and-growth processes in control samples to grain-and-twin-boundary fracture in tritium-charged-and-aged samples. Type 316L stainless steel had the highest fracture-toughness values and Type 21Cr-6Ni-9Mn had the lowest. Samples containing {sup 3}He but degassed ofmore » tritium had fracture toughness properties that were similar to uncharged samples. The results indicate that helium bubbles enhance the embrittlement effects of hydrogen by affecting the deformation properties and by increasing localized hydrogen concentrations through trapping effects.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stengl, Vaclav, E-mail: stengl@iic.cas.cz; Bludska, Jana; Oplustil, Frantisek

Highlights: {yields} New nano-dispersive materials for warfare agents decontamination. {yields} 95% decontamination activities for sulphur mustard. {yields} New materials base on titanium and manganese oxides. -- Abstract: Titanium(IV)-manganese(IV) nano-dispersed oxides were prepared by a homogeneous hydrolysis of potassium permanganate and titanium(IV) oxo-sulphate with 2-chloroacetamide. Synthesised samples were characterised using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (HD or bis(2-chloroethyl)sulphide) and soman (GD or (3,3'-dimethylbutan-2-yl)-methylphosphonofluoridate). Mn{sup 4+} content affects the decontamination activity; with increasing Mn{supmore » 4+} content the activity increases for sulphur mustard and decreases for soman. The best decontamination activities for sulphur mustard and soman were observed for samples TiMn{sub 3}7 with 18.6 wt.% Mn and TiMn{sub 5} with 2.1 wt.% Mn, respectively.« less

21. FOREBAY; GATE MECHANISM VISIBLE IN LOWER LEFT; HEADRACE ARCH ...

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

21. FOREBAY; GATE MECHANISM VISIBLE IN LOWER LEFT; HEADRACE ARCH IS IN NORTH WALL OF FOREBAY, BEHIND MASONRY ARCH IN CENTER; LOOKING NORTHEAST - Crown Roller Mill, 105 Fifth Avenue, South, West Side Milling District, Minneapolis, Hennepin County, MN

Bioaccumulation of Zn, Cu and Mn in the caviar and muscle of Persian sturgeon (Acipenser persicus) from the Caspian Sea, Iran.

PubMed

Mashroofeh, Abdulreza; Bakhtiari, Alireza Riyahi; Pourkazemi, Mohammad

2012-12-01

Concentrations of Zn, Cu and Mn were examined in caviar and muscle of the Persian sturgeon (Acipenser persicus) collected from coastal waters of south Caspian Sea during March and April, 2011. Mean Zn, Cu and Mn concentrations in caviar samples were 21.48, 2.05 and 1.66 μg g(-1) wet weight basis, respectively. The mean Zn, Cu and Mn concentrations in muscle tissues were 7.49, 1.00 and 0.34 μg g(-1) wet weight basis, respectively. The mean concentrations of Zn and Cu in caviar and muscle samples were under the permissible limits proposed by the United Kingdom's Ministry of Agriculture, Fisheries and Food (2000).

Intense Photosensitized Emission from Stoichiometric Compounds Featuring Mn(2+) in Seven- and Eightfold Coordination Environments.

PubMed

Reid, Howard O. N.; Kahwa, Ishenkumba A.; White, Andrew J. P.; Williams, David J.

1998-07-27

Synthetic, structural and luminescence studies of stoichiometric crown ether compounds of Mn(2+) in well-defined coordination environments were undertaken in an effort to understand the origin of emitting crystal defects found in cubic F23 [(K18C6)(4)MnBr(4)][TlBr(4)](2) crystals (Fender, N. S.; et al. Inorg. Chem. 1997, 36, 5539). The new compound [Mn(12C4)(2)][MnBr(4)](2)[N(CH(3))(4)](2) (3) features Mn(2+) ions in eight- and fourfold coordination environments of [Mn(12C4)(2)](2+) and MnBr(4)(2)(-) respectively, while Mn(2+) in [Mn(15C5)(H(2)O)(2)][TlBr(5)] (4) is in the sevenfold coordination polyhedron of [Mn(15C5)(H(2)O)(2)](2+). Crystal data for 3: monoclinic, P2(1)/c (No. 14); a = 14.131(3) Å, b = 12.158(1) Å, c = 14.239(2) Å, beta = 110.37(1) degrees, Z = 2, R1 = 0.039 and wR2 = 0.083. For 3, long-lived emission (77 K decay rate approximately 3 x 10 s(-)(1)) from [Mn(12C4)(2)](2+) (the first for eight-coordinate Mn(2+) in stoichiometric compounds) is observed (lambda(max) approximately 546 nm) along with that of the sensitizing MnBr(4)(2)(-) (lambda(max) approximately 513 nm), which is partially quenched. Emission from the seven-coordinate [Mn(15C5)(H(2)O)(2)](2+) species of 4 and [Mn(15C5)(H(2)O)(2)][MnBr(4)] (the first for seven-coordinate Mn(2+) in stoichiometric compounds) peaks at lambda(max) approximately 592 nm. Unusually intense absorptions attributable to the seven-coordinate species are observed at 317 ((2)T(2)((2)I) <-- (6)A(1)), 342 ((4)T(1)((4)P) <-- (6)A(1)), 406 ((4)E((4)G) <-- (6)A(1)), and 531 ((4)T(1)((4)G) <-- (6)A(1)) nm.

Unraveling the role of animal heme peroxidases in superoxide mediated Mn oxide formation

NASA Astrophysics Data System (ADS)

Learman, D. R.; Hansel, C. M.

2013-12-01

Manganese(III,IV) oxides are important in the environment as they can impact the fate of a broad range of nutrients (e.g. carbon and phosphate) and contaminates (e.g. lead and chromium). Bacteria play a valuable role in the production of Mn oxides, yet the mechanisms and physiological reasons remain unclear. Roseobacter sp. AzwK-3b, an organism within the abundant and ubiquitous Roseobacter clade, has recently been shown to oxidize Mn(II) via a novel pathway that involves enzymatic extracellular superoxide production. However, in reactions with only Mn(II) and abiotically generated superoxide, we find superoxide alone is not enough to produce Mn(III,IV) oxides. Scavenging of the byproduct hydrogen peroxide (via the addition of catalase) is required to generate Mn oxides via abiotic reaction of Mn(II) with superoxide. Thus, R. AzwK-3b must produce superoxide and also scavenge hydrogen peroxide to form Mn oxides. Further, in-gel Mn(II) oxidation assay revealed a protein band that could generate Mn oxides in the presence of soluble Mn(II). This Mn(II)-oxidizing protein band was excised from the gel and the peptides identified via mass spectrometry. An animal heme peroxidase (AHP) was the predominant protein found in this band. This protein is homologous to the AHPs previously implicated as a Mn(II)-oxidizing enzyme within the Alphaproteobacteria, Erythrobacter SD-21 and Aurantimonas manganoxydans strain SI85-9A1. Currently, protein expression of the AHPs in R. AzwK-3b is being examined to determine if expression is correlated with Mn(II) concentration or oxidative stress. Our data suggests that AHPs do not directly oxidize Mn(II) but rather plays a role in scavenging hydrogen peroxide and/or producing an organic Mn(III) ligand that complexes Mn(III) and likely aids in Mn oxide precipitation.

Synthesis and Structural Characterization of a Series of Mn(III)-OR Complexes, Including a Water-Soluble Mn(III)-OH that Promotes Aerobic Hydrogen Atom Transfer

PubMed Central

Coggins, Michael K.; Brines, Lisa M.; Kovacs, Julie A.

2013-01-01

Hydrogen atom transfer reactions (HAT) are a class of proton-coupled electron transfer (PCET) reactions used in biology to promote substrate oxidation. The driving force for such reactions depend on both the oxidation potential of the catalyst and the pKa of the proton acceptor site. Both high-valent transition-metal oxo M(IV)=O (M= Fe, Mn) and lower-valent transition-metal hydroxo compounds M(III)–OH (M= Fe, Mn) have been shown to promote these reactions. Herein we describe the synthesis, structure and reactivity properties of a series of Mn(III)-OR compounds (R= pNO2Ph(5), Ph(6), Me(7), H(8)), some of which abstract H-atoms. The Mn(III)-OH complex 8 is water-soluble and represents a rare example of a stable mononuclear Mn(III)-OH. In water, the redox potential of 8 was found to be pH-dependent and the Pourbaix (Ep,c vs pH) diagram has a slope (52 mV/pH) that is indicative of the transfer a single proton with each electron (ie, PCET). The two compounds with the lowest oxidation potential, hydroxide and methoxide-bound 7 and 8 are found to oxidize TEMPOH, whereas the compounds with the highest oxidation potential, phenol-ligated 5 and 6, are shown to be unreactive. Hydroxide-bound 8 reacts with TEMPOH an order of magnitude faster than methoxide-bound 7. Kinetic data (kH/kD= 3.1 (8), kH/kD= 2.1 (7)) are consistent with concerted H-atom abstraction. The reactive species 8 can be aerobically regenerated in H2O, and at least 10 turnovers can be achieved without significant degradation of the “catalyst”. The linear correlation between redox potential and pH, obtained from the Pourbaix diagram, was used to calculate the BDFE= 74.0±0.5 kcal/mol for Mn(II)-OH2 in water, and in MeCN its BDFE was estimated to be (70.1 kcal/mol). The reduced protonated derivative of 8, [MnII(SMe2N4(tren))(H2O)]+ (9), was estimated to have a pKa of 21.2 in MeCN. The ability (7) and inability (5 and 6) of the other members of the series to abstract a H-atom from TEMPOH was used to estimate either an upper or lower limit to the Mn(II)-O(H)R pKa based on their experimentally determined redox potentials. The trend in pKa (21.2(R=H) > 16.2(R=Me) > 13.5(R=Ph) > 12.2(R=pNO2Ph)) is shown to oppose that of oxidation potential Ep,c (−220(R= pNO2Ph) > −300(R= Ph) > −410(R= Me) > −600(R= H) mV vs Fc+/0) for this particular series. PMID:24156315

Effect of atomic order on the martensitic and magnetic transformations in Ni-Mn-Ga ferromagnetic shape memory alloys.

PubMed

Sánchez-Alarcos, V; Pérez-Landazábal, J I; Recarte, V; Rodríguez-Velamazán, J A; Chernenko, V A

2010-04-28

The influence of long-range L2(1) atomic order on the martensitic and magnetic transformations of Ni-Mn-Ga shape memory alloys has been investigated. In order to correlate the structural and magnetic transformation temperatures with the atomic order, calorimetric, magnetic and neutron diffraction measurements have been performed on polycrystalline and single-crystalline alloys subjected to different thermal treatments. It is found that both transformation temperatures increase with increasing atomic order, showing exactly the same linear dependence on the degree of L2(1) atomic order. A quantitative correlation between atomic order and transformation temperatures has been established, from which the effect of atomic order on the relative stability between the structural phases has been quantified. On the other hand, the kinetics of the post-quench ordering process taking place in these alloys has been studied. It is shown that the activation energy of the ordering process agrees quite well with the activation energy of the Mn self-diffusion process.

Synthesis and structural stability of Cr-doped Li2MnSiO4/C cathode materials by solid-state method

NASA Astrophysics Data System (ADS)

Cheng, Hong-Mei; Zhao, Shi-Xi; Wu, Xia; Zhao, Jian-Wei; Wei, Lei; Nan, Ce-Wen

2018-03-01

The crystal structure of the Li2MnSiO4 cathode material would collapse during the charge and discharge process because of that the Mn-O coordination polyhedron changed from [MnO4] into [MnO6] in the process of Mn+2 to Mn+4, but the Cr element could remain [CrO4] crystal ligand from Cr+2 to Cr+4, so Cr element substitution was used to improve the structural stability of the Li2MnSiO4 cathode material. In this work, Li2Mn1-xCrxSiO4/C nanocomposites were synthesized by solid-state method. XRD, SEM and TEM observations show that the as-prepared Li2Mn1-xCrxSiO4/C materials presents an orthorhombic crystal structure (S.G. Pmn21), the particle size of Li2Mn1-xCrxSiO4/C powder ranges from 50 to 100 nm. The XRD and XPS results indicate that Cr+2 is successfully doped into Li2MnSiO4 lattice and has well compatibility with Li2MnSiO4. The electrochemical results display that Li2Mn92.5%Cr7.5%SiO4/C exhibits significantly enhanced cycle stability and discharge capability. The initial discharge capacity of the Li2Mn92.5%Cr7.5%SiO4/C sample is 255 mAh g-1, and the discharge capacity was still about 60 mAh g-1 after 50 cycles. Furthermore, the XRD patterns, TEM images and Raman analysis reveal that the Cr doping enhances the structural stability of Li2Mn1-xCrxSiO4/C and improves the electrochemical activity of the cathode. Thus, the Li2Mn92.5%Cr7.5%SiO4/C have shown potential applications for lithium ion batteries.

Exploring Manganese Fractionation Using a Sequential Extraction Method to Evaluate Welders' Gas Metal Arc Welding Exposures during Heavy Equipment Manufacturing.

PubMed

Hanley, Kevin W; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin

2017-01-01

The National Institute for Occupational Safety and Health (NIOSH) has conducted an occupational exposure assessment study of manganese (Mn) in welding fume at three factories where heavy equipment was manufactured. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. One hundred nine worker-days were monitored for either total or respirable Mn during gas metal arc welding. The samples were analyzed using an experimental method to separate different Mn fractions based on selective chemical solubility. The full-shift total particle size Mn time-weighted average (TWA) breathing zone concentrations ranged 0.38-26 for soluble Mn in a mild ammonium acetate solution; 3.2-170 for Mn0,2+ in acetic acid; 3.1-290 for Mn3+,4+ in hydroxylamine-hydrochloride; and non-detectable (ND)-130 µg m-3 for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all the total particulate Mn TWA fractions yielded results that ranged from 6.9 to 610 µg m-3. The range of respirable size Mn TWA concentrations were 0.33-21 for soluble Mn; 15-140 for Mn0,2+; 14-170 for Mn3+,4+; 5.3-230 for insoluble Mn; and 36-530 µg m-3 for Mn (sum of fractions). Total particulate TWA GM concentrations of the Mn (sum) were 53 (GSD = 2.5), 150 (GSD = 1.7), and 120 (GSD = 1.8) µg m-3 for the three separate factories. Although all of the workers' exposures were measured below the OSHA regulatory permissible exposure limit and NIOSH recommended exposure limit for Mn, 70 welders' exposures exceeded the ACGIH Threshold Limit Values® for total Mn (100 µg m-3) and 29 exceeded the recently adopted respirable Mn TLV (20 µg m-3). This study shows that a welding fume exposure control and management program is warranted for Mn, which includes improved exhaust ventilation and may necessitate the use of respiratory protection, especially for welding parts that impede air circulation. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2017.

78 FR 21861 - Tribal Consultation on the Draft Regulations Governing the Tribal Transportation Program

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-12

... regarding the following topics: On July 6, 2012, Moving Ahead for Progress in the 21st Century Act (MAP-21...:30 p.m. May 16, 2013 Phoenix, AZ 9 a.m.-4:30 p.m. May 21, 2013 Minneapolis, MN 9 a.m.-4:30 p.m... President Obama and became effective on October 1, 2012. Section 1119 of MAP-21 struck the existing laws...

Pre-weaning Mn exposure leads to prolonged astrocyte activation and lasting effects on the dopaminergic system in adult male rats

PubMed Central

Kern, Cynthia; Smith, Donald R.

2010-01-01

Little is known about the effects of manganese (Mn) exposure over neurodevelopment and whether these early insults result in effects lasting into adulthood. To determine if early Mn exposure produces lasting neurobehavioral and neurochemical effects, we treated neonate rats with oral Mn (0, 25, or 50 mg Mn/kg/d over PND 1–21) and evaluated 1) behavioral performance in the open arena in the absence (PND 97) and presence (PND 98) of a d-amphetamine challenge, 2) brain dopamine D1 and D2-like receptors and dopamine transporter densities in the prefrontal cortex, striatum, and nucleus accumbens (PND 107), and 3) astrocyte marker glial fibrillary acidic protein (GFAP) levels in these same brain regions (PND 24 and 107). We found that pre-weaning Mn exposure did not alter locomotor activity or behavior disinhibition in adult rats, though Mn-exposed animals did exhibit an enhanced locomotor response to d-amphetamine challenge. Pre-weaning Mn exposure led to increased D1 and D2 receptor levels in the nucleus accumbens and prefrontal cortex, respectively, compared to controls. We also found increased GFAP expression in the prefrontal cortex in Mn-exposed PND 24 weanlings, and increased GFAP levels in prefrontal cortex, medial striatum and nucleus accumbens of adult (PND 107) rats exposed to pre-weaning Mn, indicating an effect of Mn exposure on astrogliosis that persisted and/or progressed to other brain regions in adult animals. These data show that pre-weaning Mn exposure leads to lasting molecular and functional impacts in multiple brain regions of adult animals, long after brain Mn levels returned to normal. PMID:20963817

Synthesis and stability of hetaerolite, ZnMn2O4, at 25°C

USGS Publications Warehouse

Hem, J.D.; Roberson, C.E.; Lind, C.J.

1987-01-01

A precipitate of nearly pure hetaerolite, ZnMn2O4, a spinel-structured analog of hausmannite, Mn3O4, was prepared by an irreversible wprecipitation of zinc with manganese at 25°C. The synthesis technique entailed constant slow addition of a dilute solution of Mn2+ and Zn2+ chlorides having a Mn/Zn ratio of 2:1 to a reaction vessel that initially contained distilled deionized water, maintained at a pH of 8.50 by addition of dilute NaOH by an automated pH stat, with continuous bubbling of CO2-free air. The solid was identified by means of X-ray diffraction and transmission electron microscopy and consisted of bipyramidal crystals generally less than 0.10 μm in diameter. Zn2+ ions are able to substitute extensively for Mn2+ ions that occupy tetrahedral sites in the hausmannite structure.Hetaerolite appears to be more stable than hausmannite with respect to spontaneous conversion to γMnOOH. The value of the standard free energy of formation of hetaerolite was estimated from the experimental data to be −289.4 ± 0.8 kcal per mole. Solids intermediate in composition between hetaerolite and hausmannite can be prepared by altering the Mn/Zn ratio in the feed solution.

Activation of Neurokinin 3 Receptors in the Median Preoptic Nucleus Decreases Core Temperature in the Rat

PubMed Central

Dacks, Penny A.; Krajewski, Sally J.

2011-01-01

Estrogens have pronounced effects on thermoregulation, as illustrated by the occurrence of hot flushes secondary to estrogen withdrawal in menopausal women. Because neurokinin B (NKB) gene expression is markedly increased in the infundibular (arcuate) nucleus of postmenopausal women, and is modulated by estrogen withdrawal and replacement in multiple species, we have hypothesized that NKB neurons could play a role in the generation of flushes. There is no information, however, on whether the primary NKB receptor [neurokinin 3 receptor (NK3R)] modulates body temperature in any species. Here, we determine the effects of microinfusion of a selective NK3R agonist (senktide) into the rat median preoptic nucleus (MnPO), an important site in the heat-defense pathway. Senktide microinfusion into the rat MnPO decreased core temperature in a dose-dependent manner. The hypothermia induced by senktide was similar in ovariectomized rats with and without 17β-estradiol replacement. The hypothermic effect of senktide was prolonged in rats exposed to an ambient temperature of 29.0 C, compared with 21.5 C. Senktide microinfusion also altered tail skin vasomotion in rats exposed to an ambient temperature of 29.0 but not 21.5 C. Comparisons of the effects of senktide at different ambient temperatures indicated that the hypothermia was not secondary to thermoregulatory failure or a reduction in cold-induced thermogenesis. Other than a very mild increase in drinking, senktide microinfusion did not affect behavior. Terminal fluorescent dextran microinfusion showed targeting of the MnPO and adjacent septum, and immunohistochemical studies revealed that senktide induced a marked increase in Fos-activation in the MnPO. Because MnPO neurons expressed NK3R-immunoreactivity, the induction of MnPO Fos by senktide is likely a direct effect. By demonstrating that NK3R activation in the MnPO modulates body temperature, these studies support the hypothesis that hypothalamic NKB neurons could be involved in the generation of menopausal flushes. PMID:22028440

Chemical Synthesis of Sea-Urchin Shaped 3D-MnO2 Nano Structures and Their Application in Supercapacitors.

PubMed

Singu, Bal Sydulu; Hong, Sang Eun; Yoon, Kuk Ro

2016-06-01

Sea-urchin shaped α-MnO2 hierarchical nano structures have been synthesized by facile thermal method without using any hard or soft template under the mild conditions. The structural and morphology of the 3D-MnO2 was characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). From the XRD analysis indicates that MnO2 present in the α form. Morphology analysis shows that α-MnO2 sea-urchins are made by stacked nanorods, the diameter and length of the stacked nanorods present in the range of 50-120 nm and 200-400 nm respectively. The electrochemical behaviour of α-MnO2 has been investigated by cyclic voltammetry (CV) and charge-discharge (CD). The specific capacitance, energy density and power density are 212.0 F g(-1), 21.2 Wh kg(-1) and 1200 W kg(-1) respectively at the current density of 2 A g(-1). The retention of the specific capacitance after completion of 1000 charge-discharge cycles is around 97%. The results reveal that the prepared Sea-urchin shaped α-MnO2 has high specific capacitance and exhibit excellent cycle life.

Dramatic Influence of an Anionic Donor on the Oxygen-Atom Transfer Reactivity of a MnV–Oxo Complex

PubMed Central

Neu, Heather M; Quesne, Matthew G; Yang, Tzuhsiung; Prokop-Prigge, Katharine A; Lancaster, Kyle M; Donohoe, James; DeBeer, Serena; de Visser, Sam P; Goldberg, David P

2014-01-01

Addition of an anionic donor to an MnV(O) porphyrinoid complex causes a dramatic increase in 2-electron oxygen-atom-transfer (OAT) chemistry. The 6-coordinate [MnV(O)(TBP8Cz)(CN)]− was generated from addition of Bu4N+CN− to the 5-coordinate MnV(O) precursor. The cyanide-ligated complex was characterized for the first time by Mn K-edge X-ray absorption spectroscopy (XAS) and gives Mn–O=1.53 Å, Mn–CN=2.21 Å. In combination with computational studies these distances were shown to correlate with a singlet ground state. Reaction of the CN− complex with thioethers results in OAT to give the corresponding sulfoxide and a 2e−-reduced MnIII(CN)− complex. Kinetic measurements reveal a dramatic rate enhancement for OAT of approximately 24 000-fold versus the same reaction for the parent 5-coordinate complex. An Eyring analysis gives ΔH≠=14 kcal mol−1, ΔS≠=−10 cal mol−1 K−1. Computational studies fully support the structures, spin states, and relative reactivity of the 5- and 6-coordinate MnV(O) complexes. PMID:25256417

Characteristics of 5M modulated martensite in Ni-Mn-Ga magnetic shape memory alloys

NASA Astrophysics Data System (ADS)

Ćakır, A.; Acet, M.; Righi, L.; Albertini, F.; Farle, M.

2015-09-01

The applicability of the magnetic shape memory effect in Ni-Mn-based martensitic Heusler alloys is closely related to the nature of the crystallographically modulated martensite phase in these materials. We study the properties of modulated phases as a function of temperature and composition in three magnetic shape memory alloys Ni49.8Mn25.0Ga25.2, Ni49.8Mn27.1Ga23.1 and Ni49.5Mn28.6Ga21.9. The effect of substituting Ga for Mn leads to an anisotropic expansion of the lattice, where the b-parameter of the 5M modulated structure increases and the a and c-parameters decrease with increasing Ga concentration. The modulation vector is found to be both temperature and composition dependent. The size of the modulation vector corresponds to an incommensurate structure for Ni49.8Mn25.0Ga25.2 at all temperatures. For the other samples the modulation is incommensurate at low temperatures but reaches a commensurate value of q ≈ 0.400 close to room temperature. The results show that commensurateness of the 5M modulated structure is a special case of incommensurate 5M at a particular temperature.

Incorporation of μ3-CO3 into an MnIII/MnIV Mn12 cluster: {[(cyclam)MnIV(μ-O)2MnIII(H2O)(μ-OH)]6(μ3-CO3)2}Cl8·24H2O

PubMed Central

Levaton, Ben B.; Olmstead, Marilyn M.

2010-01-01

The centrosymmetric title cluster, hexa­aquadi-μ3-carbonato-hexa­cyclamhexa-μ2-hydroxido-dodeca-μ2-oxido-hexa­mang­an­ese(IV)hexa­manganese(III) octa­chloride tetra­cosa­hydrate, [Mn12(CO3)2O12(OH)6(C10H24N4)6(H2O)6]Cl8·24H2O, has two μ3-CO3 groups that not only bridge octahedrally coordinated MnIII ions but also act as acceptors to two different kinds of hydrogen bonds. The carbonate anion is planar within experimental error and has an average C—O distance of 1.294 (4) Å. The crystal packing is stabilized by O—H⋯Cl, O—H⋯O, N—H⋯Cl and N—H⋯O hydrogen bonds. Two of the four independent chloride ions are disordered over five positions, and eight of the 12 independent water mol­ecules are disordered over 21 positions. PMID:21587382

Effect of dietary manganese on antioxidant status and expressions of heat shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures.

PubMed

Zhu, Yong-Wen; Lu, Lin; Li, Wen-Xiang; Zhang, Li-Yang; Ji, Cheng; Lin, Xi; Liu, Hsiao-Ching; Odle, Jack; Luo, Xu-Gang

2016-12-01

To investigate the effect of Mn on antioxidant status and on the expressions of heat shock proteins/factors in tissues of laying broiler breeders subjected to heat challenge, we used a completely randomised design (n 6) with a factorial arrangement of 2 environmental temperatures (normal, 21±1°C, and high, 32±1°C)×3 dietary Mn treatments (a Mn-unsupplemented basal diet (CON), or a basal diet supplemented with 120 mg Mn/kg diet, either as inorganic Mn sulphate (iMn) or as organic Mn proteinate (oMn)). There were no interactions (P>0·10) between environmental temperature and dietary Mn in any of the measured indices. High temperature decreased (P<0·003) Mn content, and also tended (P=0·07) to decrease Cu Zn superoxide dismutase (CuZnSOD) activity in the liver and heart. However, an increased Mn superoxide dismutase (MnSOD) activity (P<0·05) and a slight increase in malondialdehyde level (P=0·06) were detected in breast muscle. Up-regulated (P<0·05) expressions of heat shock factor 1 (HSF1) and HSF3 mRNA and heat shock protein 70 (HSP70) mRNA and protein were found in all three tissues. Broiler breeders fed either iMn or oMn had higher tissue Mn content (P<0·0001), heart MnSOD and CuZnSOD activities (P<0·01) and breast muscle MnSOD protein levels (P<0·05), and lower (P<0·05) breast muscle HSP70 mRNA and protein levels compared with those fed CON. Broiler breeders fed oMn had higher (P<0·03) bone Mn content than those fed iMn. These results indicate that high temperature decreases Mn retention and increases HSP70, HSF1 and HSF3 expressions in the tissues of laying broiler breeders. Furthermore, dietary supplementation with Mn in either source may enhance the heart's antioxidant ability and inhibit the expression of HSP70 in breast muscle. Finally, the organic Mn appears to be more available than inorganic Mn for bone in laying broiler breeders regardless of environmental temperatures.

Development of a Design Tool for Planning Aqueous Amendment Injection Systems

DTIC Science & Technology

2012-08-01

Chemical Oxidation with Permanganate (MnO4- ) ...................................... 2 1.4 IMPLEMENTATION ISSUES...17 6.4 SS DESIGN TOOL DEVELOPMENT AND EVALUATION ........................... 19 7.0 CHEMICAL OXIDATION WITH PERMANGANATE ...21 7.1 NUMERICAL MODELING OF PERMANGANATE DISTRIBUTION ........... 21 7.2 CDISCO DEVELOPMENT AND EVALUATION

Investigation of spin-dependent transports and microstructure in NiMnSb-based magnetoresistive devices

NASA Astrophysics Data System (ADS)

Qu, Guanxiong; Cheng, P.-H.; Du, Ye; Sakuraba, Yuya; Kasai, Shinya; Hono, Kazuhiro

2017-11-01

We have fabricated fully epitaxial current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices using C1b-half Heusler compound NiMnSb, the first candidate of the half-metallic material, as the electrode with a Ag spacer. The device shows magnetoresistance ratios of 25% at 4.2 K and 9.6% at 290 K, which are one of the highest values for the CPP-GMR with half-Heusler compounds. However, these values are much lower compared to those reported for CPP-GMR devices with L21-full Heusler compounds. Careful analysis of the microstructure using scanning transmission electron microscopy and energy dispersive spectroscopy through the upper NiMnSb/Ag interface indicates the heterogeneous formation of Ag-rich solid solution or the island growth of Ag on top of NiMnSb, which clarified a difficulty in evaluating an intrinsic spin-polarization in NiMnSb from CPP-GMR devices. Thus, to evaluate a spin-polarization of a NiMnSb thin film, we fabricated non-local spin valve (NLSV) devices using NiMnSb with Cu channel wires, which is free from the diffusion of Cu to NiMnSb because of no annealing proccess after deposition of Cu. Finally, intrinsic spin polarization of the NiMnSb single layer was extrapolated to be around 50% from NLSV, suggesting a difficulty in obtaining half-metallic nature in the NiMnSb epitaxial thin film.

Evaluation of distribution and manganese availability in soils under soybean cultivation

NASA Astrophysics Data System (ADS)

Mendes Coutinho, Edson Luiz; de Cássia Gomes São João, Andréia; Mendes Coutinho Neto, André; Corá, José Eduardo; Fernandes, Carolina

2013-04-01

Manganese (Mn) deficiency in soybean became a problem in Brazil, mainly, due to soil low fertility use or soil high pH due to incorrect lime use. However, the manganese deficiency have not been thoroughly investigated. The effect of Mn soil application on Mn distribution among exchangeable, organic matter, amorphous Fe and Al oxides, crystalline Fe and Al oxides, and residual fractions were studied on a Typic Quartzipsament (RQ), a clayey Typic Haplustox (LVA) and a sandy clay loam Typic Haplustox (LV), in a greenhouse experiment carried out in Jaboticabal (SP) - Brazil (21°14'05'' S and 48°17'09'' W). A complete randomized design with three replications of treatments in a 3 x 6 factorial arrangement (three soils and six manganese rates) was used. Five soybean plants were grown during 34 days in pots with 2.5 kg of soil. The Mn contents in these fractions were correlated with those extracted by DTPA and by Mehlich-1 extractants and with soybean shoot Mn contents. Mn rates (0, 5, 10, 20, 40 and 60 mg kg-1) were applied using manganese sulphate (MnSO4). In the Oxisols, most of the Mn was associated with the Fe and Al oxides (amorphous and crystalline) and residual fractions. In the sandy soil (RQ), higher contents were found in exchangeable and residual fractions. Exchangeable fraction was the most important Mn supplier to soybean plants. Multiple regression analysis showed that Mn extracted by DTPA and Mehlich-1 were associated with soil exchangeable fraction.

Influence of SaOS-2 cells on corrosion behavior of cast Mg-2.0Zn0.98Mn magnesium alloy.

PubMed

Witecka, Agnieszka; Yamamoto, Akiko; Święszkowski, Wojciech

2017-02-01

In this research, the effect of the presence of living cells (SaOS-2) on in vitro degradation of Mg-2.0Zn-0.98Mn (ZM21) magnesium alloy was examined by two methods simple immersion/cell culture tests and electrochemical measurements (electrochemical impedance spectroscopy and potentiodynamic polarization) under cell culture conditions. In immersion/cell culture tests, when SaOS-2 cells were cultured on ZM21 samples, pH of cell culture medium decreased, therefore weight loss and Mg 2+ ion release from the samples increased. Electrochemical measurements revealed the presence of living cells increased corrosion rate (I corr ) and decreased polarization resistance (R p ) after 48h of incubation. This acceleration of ZM21 corrosion can mainly be attributed to the decrease of medium pH due to cellular metabolic activities. Copyright © 2016 Elsevier B.V. All rights reserved.

Decontamination System Utilizing Hydrogen Peroxide, UV Light and Catalytic Surfaces

DTIC Science & Technology

1992-02-01

Min %DMO RecoveredDisk# Catalyst (relative to control) 1 Ag 2 0 5.4 2 Ag2 0 10.1 4 FeTiO3 56 5 FeTio3 48 7 None 558 None 56 Control None 100 Ag 2 0...Std. Ag2 0 44 FeTiO3 Std. FeTiO3 100 Reference 87 - 36 - Table 9g. Experiment U, 1-09-91, 50% H2 02 , No UV Light, Run Time - 40 Min % DMO...Ag 2 0 2 7.8 44 1-09 T FeTiO3 2 52 100 1-09 U MnO 2 59 921-09 U Mn304 2 62 89 1-21 Y Ag 2 S/CaCO3 2 36 103 1-21 Y Ag 2 S 2 39 100 1-21 Z FeS2 2 6.0

Enhanced catalytic performance for methane combustion of 3DOM CoFe2O4 by co-loading MnOx and Pd-Pt alloy nanoparticles

NASA Astrophysics Data System (ADS)

Li, Xiangyu; Liu, Yuxi; Deng, Jiguang; Xie, Shaohua; Zhao, Xingtian; Zhang, Yang; Zhang, Kunfeng; Arandiyan, Hamidreza; Guo, Guangsheng; Dai, Hongxing

2017-05-01

Three-dimensionally ordered macroporous (3DOM) CoFe2O4, zMnOx/3DOM CoFe2O4 (z = 4.99-12.30 wt%), and yPd-Pt/6.70 wt% MnOx/3DOM CoFe2O4 (y = 0.44-1.81 wt%; Pd/Pt molar ratio = 2.1-2.2) have been prepared using the polymethyl methacrylate microspheres-templating, incipient wetness impregnation, and bubble-assisted polyvinyl alcohol-protected reduction strategies, respectively. All of the samples were characterized by means of various techniques. Catalytic performance of the samples was measured for methane combustion. It is shown that the as-prepared samples exhibited a high-quality 3DOM structure (103 ± 20 nm in pore size) and a surface area of 19-28 m2/g, and the noble metal or alloy nanoparticles (NPs) with a size of 2.2-3.0 nm were uniformly dispersed on the macropore wall surface of 3DOM CoFe2O4. The loading of MnOx on CoFe2O4 gave rise to a slight increase in activity, however, the dispersion of Pd-Pt NPs on 6.70MnOx/3DOM CoFe2O4 significantly enhanced the catalytic performance, with the 1.81Pd2.1Pt/6.70MnOx/3DOM CoFe2O4 sample showing the highest activity (T10% = 255 °C, T50% = 301 °C, and T90% = 372 °C at a space velocity of 20,000 mL/(g h)). We believe that the excellent catalytic activity of 1.81Pd2.1Pt/6.70MnOx/3DOM CoFe2O4 was related to its well-dispersed Pd-Pt alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between MnOx or Pd-Pt NPs and 3DOM CoFe2O4.

Enhancement of Curie temperature in Mn{sub 2}RuSn by Co substitution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, A.; Huh, Y.; Fuglsby, R.

2015-04-21

The Co-substituted Mn{sub 2}RuSn nanomaterials, namely, Mn{sub 2}Ru{sub 0.5}Co{sub 0.5}Sn and Mn{sub 2}Ru{sub 0.35}Co{sub 0.65}Sn have been synthesized and investigated. The presence of Co in the Mn{sub 2}RuSn (a = 6.21 Å) decreased the lattice parameter, where a = 6.14 Å and 6.12 Å for the as prepared Mn{sub 2}Ru{sub 0.5}Co{sub 0.5}Sn and Mn{sub 2}Ru{sub 0.35}Co{sub 0.65}Sn, respectively. The samples show a ferrimagnetic spin order with relatively small coercivities, similar to those of soft magnetic materials. There is a substantial increase in the Curie temperature (T{sub c} = 448 K for Mn{sub 2}Ru{sub 0.5}Co{sub 0.5}Sn and 506 K for Mn{sub 2}Ru{sub 0.35}Co{sub 0.65}Sn) of Mn{sub 2}RuSn (T{sub c} = 272.1 K) due to Comore » substitution, which is a result of strengthening of the positive exchange interaction in this material. These materials are highly stable against heat treatment of up to 450 °C. The first-principles calculations are consistent with our experimentally observed structural and magnetic properties. They also provide insight on how the magnetic and electronic structures change when Ru is replaced with Co in Mn{sub 2}RuSn.« less

Effect of dietary manganese on antioxidant status and expression levels of heat-shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures.

PubMed

Zhu, Yong-Wen; Lu, Lin; Li, Wen-Xiang; Zhang, Li-Yang; Ji, Cheng; Lin, Xi; Liu, Hsiao-Ching; Odle, Jack; Luo, Xu-Gang

2015-12-28

To investigate the effect of Mn on antioxidant status and expression levels of heat-shock proteins/factors in tissues of laying broiler breeders subjected to heat challenge, we used a completely randomised design (n 6) with a factorial arrangement of 2 environmental temperatures (normal, 21 (sem 1)°C and high, 32 (sem 1)°C)×3 dietary Mn treatments (an Mn-unsupplemented basal diet (CON), or a basal diet supplemented with 120 mg Mn/kg diet as inorganic Mn sulphate (iMn) or organic Mn proteinate (oMn)). There were no interactions (P>0·10) between environmental temperature and dietary Mn in all of the measured indices. High temperature decreased (P<0·003) Mn content, and also tended (P=0·07) to decrease copper zinc superoxide dismutase (CuZnSOD) activity in the liver and heart. However, an increased manganese superoxide dismutase (MnSOD) activity (P<0·05) and a slight increase of malondialdehyde level (P=0·06) were detected in breast muscle. Up-regulated (P<0·05) expression levels of heat-shock factor 1 (HSF1) and HSF3 mRNA and heat-shock protein 70 (HSP70) mRNA and protein were found in all three tissues. Broiler breeders fed either iMn or oMn had higher tissue Mn content (P<0·0001), heart MnSOD and CuZnSOD activities (P<0·01) and breast muscle MnSOD protein levels (P<0·05), and lower (P<0·05) breast muscle HSP70 mRNA and protein levels than those fed CON. Broiler breeders fed oMn had higher (P<0·03) bone Mn content than those fed iMn. These results indicate that high temperature decreases Mn retention and increases HSP70 and HSF1, HSF3 expression levels in tissues of laying broiler breeders. Furthermore, dietary supplementation with Mn in either source may enhance heart antioxidant ability and inhibit the expression of HSP70 in breast muscle. Finally, the organic Mn appears to be more available than inorganic Mn for bone in laying broiler breeders regardless of environmental temperatures.

Fractionation and risk assessment of Fe and Mn in surface sediments from coastal sites of Sonora, Mexico (Gulf of California).

PubMed

Jara-Marini, Martín E; García-Camarena, Raúl; Gómez-Álvarez, Agustín; García-Rico, Leticia

2015-07-01

The aim of this study was to evaluate Fe and Mn distribution in geochemical fractions of the surface sediment of four oyster culture sites in the Sonora coast, Mexico. A selective fractionation scheme to obtain five fractions was adapted for the microwave system. Surface sediments were analyzed for carbonates, organic matter contents, and Fe and Mn in geochemical fractions. The bulk concentrations of Fe ranged from 10,506 to 21,918 mg/kg (dry weight, dry wt), and the bulk concentrations of Mn ranged from 185.1 to 315.9 mg/kg (dry wt) in sediments, which was low and considered as non-polluted in all of the sites. The fractionation study indicated that the major geochemical phases for the metals were the residual, as well as the Fe and Mn oxide fractions. The concentrations of metals in the geochemical fractions had the following order: residual > Fe and Mn oxides > organic matter > carbonates > interchangeable. Most of the Fe and Mn were linked to the residual fraction. Among non-residual fractions, high percentages of Fe and Mn were linked to Fe and Mn oxides. The enrichment factors (EFs) for the two metals were similar in the four studied coasts, and the levels of Fe and Mn are interpreted as non-enrichment (EF < 1) because the metals concentrations were within the baseline concentrations. According to the environmental risk assessment codes, Fe and Mn posed no risk and low risk, respectively. Although the concentrations of Fe and Mn were linked to the residual fraction, the levels in non-residual fractions may significantly result in the transference of other metals, depending on several physico-chemical and biological factors.

Evidence for single-chain magnet behavior in a Mn(III)-Ni(II) chain designed with high spin magnetic units: a route to high temperature metastable magnets.

PubMed

Clérac, Rodolphe; Miyasaka, Hitoshi; Yamashita, Masahiro; Coulon, Claude

2002-10-30

We herein present the synthesis, crystal structure, and magnetic properties of a new heterometallic chain of MnIII and NiII ions, [Mn2(saltmen)2Ni(pao)2(py)2](ClO4)2 (1) (saltmen2- = N,N'-(1,1,2,2-tetramethylethylene) bis(salicylideneiminate) and pao- = pyridine-2-aldoximate). The crystal structure of 1 was investigated by X-ray crystallographic analysis: compound 1 crystallized in monoclinic, space group C2/c (No. 15) with a = 21.140(3) A, b = 15.975(1) A, c = 18.6212(4) A, beta = 98.0586(4) degrees , V = 6226.5(7) A3, and Z = 4. This compound consists of two fragments, the out-of-plane dimer [Mn2(saltmen)2]2+ as a coordination acceptor building block and the neutral mononuclear unit [Ni(pao)2(py)2] as a coordination donor building block, forming an alternating chain having the repeating unit [-Mn-(O)2-Mn-ON-Ni-NO-]n. In the crystal structure, each chain is well separated with a minimum intermetallic distance between Mn and Ni ions of 10.39 A and with the absence of interchain pi overlaps between organic ligands. These features ensure a good magnetic isolation of the chains. The dc and ac magnetic measurements were performed on both the polycrystalline sample and the aligned single crystals of 1. Above 30 K, the magnetic susceptibility of this one-dimensional compound was successfully described in a mean field approximation as an assembly of trimers (Mn...Ni...Mn) with a NiII...MnIII antiferromagnetic interaction (J = -21 K) connected through a ferromagnetic MnIII...MnIII interaction (J'). However, the mean field theory fails to describe the magnetic behavior below 30 K emphasizing the one-dimensional magnetic character of the title compound. Between 5 and 15 K, the susceptibility in the chain direction was fitted to a one-dimensional Ising model leading to the same value of J'. Hysteresis loops are observed below 3.5 K, indicating a magnet-type behavior. In the same range of temperature, combined ac and dc measurements show a slow relaxation of the magnetization. This result indicates the presence of a metastable state without magnetic long-range order. This material is the first experimental design of a heterometallic chain with ST = 3 magnetic units showing a "single-chain magnet" behavior predicted in 1963 by R. J. Glauber for an Ising one-dimensional system. This work opens new perspectives for one-dimensional systems to obtain high temperature metastable magnets by combining high spin magnetic units, strong interunit interactions, and uniaxial anisotropy.

Airport Activity Statistics of Certificated Route Air Carriers, 1992

DTIC Science & Technology

1992-12-31

PERWFE STATE ON US. AREA TYPE OF DEPARTURES CO CARR OPERAllON" AMCRT S UN A SHEDULEDAIMPMF mN SNAMUU SW SCHEOUUED NEW YOK- CAMu NEW YORK--C•n•tnw (LA...20,727 21 20.748 21,163 JACKSWONVILLECAMP LEJEUNE ( ALBERT J ELLIS) ......................................... US--U.S. AIR

Pathogenic prion protein is degraded by a manganese oxide mineral found in soils

USGS Publications Warehouse

Russo, F.; Johnson, C.J.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.

2009-01-01

Prions, the aetiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. Here, we report the abiotic degradation of pathogenic prion protein (PrPTSE) by a synthetic analogue of naturally occurring birnessite minerals. Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as a solution's pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg MnO2 ml-1 (PrPTSE:MnO2=1 : 110) decreased PrPTSE levels by ???4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals. ?? 2009 SGM.

Non-Born-Oppenheimer Spectroscopy of Cyclic Triatomics

DTIC Science & Technology

2011-10-11

n nmnm mn m nm nm nm nm ss n IV E 2/ if,2/1 2/ if, ])2/1()/[( )2/1()/( 2 1 12 22 222 22 2/,,4 23 )3(   Here ZPE ...integer values of m . The perturbation theory expression gives us seven parameters for a non-linear fitting problem: ZPE , 0I , 1I , 2I , 3V , 6V and

Critical Evaluations and Thermodynamic Optimizations of the MnO-Mn2O3-SiO2 and FeO-Fe2O3-MnO-Mn2O3-SiO2 Systems

NASA Astrophysics Data System (ADS)

Kang, Youn-Bae; Jung, In-Ho

2017-06-01

A critical evaluation and thermodynamic modeling for thermodynamic properties of all oxide phases and phase diagrams in the Fe-Mn-Si-O system (MnO-Mn2O3-SiO2 and FeO-Fe2O3-MnO-Mn2O3-SiO2 systems) are presented. Optimized Gibbs energy parameters for the thermodynamic models of the oxide phases were obtained which reproduce all available and reliable experimental data within error limits from 298 K (25°C) to above the liquidus temperatures at all compositions covering from known oxide phases, and oxygen partial pressure from metal saturation to 0.21 bar. The optimized thermodynamic properties and phase diagrams are believed to be the best estimates presently available. Slag (molten oxide) was modeled using the modified quasichemical model in the pair approximation. Olivine (Fe2SiO4-Mn2SiO4) was modeled using two-sublattice model in the framework of the compound energy formalism (CEF), while rhodonite (MnSiO3-FeSiO3) and braunite (Mn7SiO_{12} with excess Mn2O3) were modeled as simple Henrian solutions. It is shown that the already developed models and databases of two spinel phases (cubic- and tetragonal-(Fe, Mn)3O4) using CEF [Kang and Jung, J. Phys. Chem. Solids (2016), vol. 98, pp. 237-246] can successfully be integrated into a larger thermodynamic database to be used in practically important higher order system such as silicate. The database of the model parameters can be used along with a software for Gibbs energy minimization in order to calculate any type of phase diagram section and thermodynamic properties.

Texture and structure contribution to low-temperature plasticity enhancement of Mg-Al-Zn-Mn Alloy MA2-1hp after ECAP and annealing

NASA Astrophysics Data System (ADS)

Serebryany, V. N.; D'yakonov, G. S.; Kopylov, V. I.; Salishchev, G. A.; Dobatkin, S. V.

2013-05-01

Equal channel angular pressing (ECAP) in magnesium alloys due to severe plastic shear deformations provides both grain refinement and the slope of the initial basal texture at 40°-50° to the pressing direction. These changes in microstructure and texture contribute to the improvement of low-temperature plasticity of the alloys. Quantitative texture X-ray diffraction analysis and diffraction of backscattered electrons are used to study the main textural and structural factors responsible for enhanced low-temperature plasticity based on the example of magnesium alloy MA2-1hp of the Mg-Al-Zn-Mn system. The possible mechanisms of deformation that lead to this positive effect are discussed.

Unsaturated Mn complex decorated hybrid thioarsenates: Syntheses, crystal structures and physical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yue, Cheng-Yang; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002; Lei, Xiao-Wu, E-mail: xwlei_jnu@163.com

2016-03-15

The incorporation of unsaturated [Mn(1,2-dap)]{sup 2+}, [Mn(1,2-dap){sub 2}]{sup 2+}, [Mn(2,2-bipy)]{sup 2+} (1,2-dap=1,2-diaminopropane) complex cations with thioarsenate anions of [As{sup III}S{sub 3}]{sup 3−} and [As{sup V}S{sub 4}]{sup 3−} led to three new hybrid manganese thioarsenates, namely, [Mn(1,2-dap)]{sub 2}MnAs{sub 2}S{sub 6} (1), [Mn(1,2-dap){sub 2}]{[Mn(1,2-dap)]_2As_2S_8} (2) and (NH{sub 4})[Mn(2,2-bipy){sub 2}]AsS{sub 4} (3). In compound 1, the unsaturated [Mn(1,2-dap)]{sup 2+} complexes, [MnS{sub 4}]{sup 6−} tetrahedra and [As{sup III}S{sub 3}]{sup 3−} trigonal-pyramids are condensed to form the 1D [Mn(1,2-dap)]{sub 2}MnAs{sub 2}S{sub 6} chain, whereas compound 2 features 2D layer composed of [Mn(1,2-dap)]{sup 2+} and [Mn(1,2-dap){sub 2}]{sup 2+} complexes as well as [As{sup V}S{sub 4}]{sup 3−}more » tetrahedral units. For compound 3, two [As{sup V}S{sub 4}]{sup 3−} anions bridge two [Mn(2,2-bipy)]{sup 2+} complex cations into a butterfly like {[Mn(2,2-bipy)]_2As_2S_8}{sup 2−} anionic unit. Magnetic measurements indicate the ferrimagnetic behavior for compound 1 and antiferromagnetic (AF) behaviors for compounds 2–3. The UV–vis diffuse-reflectance measurements and electronic structural calculations based on density functional theory (DFT) revealed the title compounds belong to semiconductors with band gaps of 2.63, 2.21, and 1.97 eV, respectively. The narrow band-gap of compound 3 led to the efficient and stable photocatalytic degradation activity over organic pollutant than N-doped P25 under visible light irradiation. - Highlights: Three new hybrid manganese thioarsenates have been prepared and structurally characterized. These hybrid phases feature interesting magnetic and visible light responding photocatalytic properties.« less

Composition and genesis of ferromanganese deposits from the northern South China Sea

NASA Astrophysics Data System (ADS)

Zhong, Yi; Chen, Zhong; González, Francisco Javier; Hein, James R.; Zheng, Xufeng; Li, Gang; Luo, Yun; Mo, Aibin; Tian, Yuhang; Wang, Shuhong

2017-05-01

Marine ferromanganese (Fe-Mn) nodules and crusts are archives of past environmental conditions and potential mineral resources. Over the last 30 years, many have been discovered in the northern South China Sea (SCS). To determine the origin of the Fe-Mn deposits, a comprehensive laboratory analysis of physical properties, mineralogy and geochemistry was conducted on newly collected Fe-Mn nodule/crust samples. The results revealed that there are three types of Fe-Mn deposits: (1) Fe-rich nodules containing essentially goethite occur on the northeastern slope of the SCS, with high Fe, low Mn (Mn/Fe = 0.03) and low trace metals and rare earth elements concentrations; (2) Smooth Fe-Mn nodules and crusts composed of asbolane, todorokite and CFA occur along the northwestern marginal of the SCS that have similar Fe and Mn contents (Mn/Fe = 1.21), moderate trace metal enrichments, and a positive Ce anomaly; (3) Fe-Mn nodules and crusts composed of asbolane, todorokite and birnessite that occur in the central basin of the SCS have higher Mn and lower Fe contents (Mn/Fe = 1.45). This depositional pattern was associated with major changes in oceanographic conditions and tectonic regimes. The northeastern slope deposits occur in a contourite depositional system, are strongly enriched in Fe relative to Mn (average 38.7% and 0.96%, respectively), formed from the combination of hydrogenetic and diagenetic processes. We propose a new genetic model for Fe-Mn nodules, which formed through the oxidation of pyrite and pyrite-barite concretions that formed by rapid early diagenetic growth (average 3320 mm/Myr) on continental margins above the carbonate compensation depth, and dominated by hydrocarbon seep structures and strong erosive action of bottom currents along the northeastern slope. In contrast, the introduction of vigorous deep-water flow from the North Pacific promoted the slow growth (4-7 mm/Myr) of hydrogenetic Fe-Mn nodules and crusts along the northwestern margin. Finally, hydrogenetic growth of Fe-Mn nodules and crusts in the central basin may have been enhanced by volcanic processes. Our data provide new insights into the genesis and province characteristics of the Fe-Mn nodules and crusts of the northern SCS.

Failure of antimony trioxide to induce micronuclei or chromosomal aberrations in rat bone-marrow after sub-chronic oral dosing.

PubMed

Kirkland, David; Whitwell, James; Deyo, James; Serex, Tessa

2007-03-05

Antimony trioxide (Sb2O3, CAS 1309-64-4) is widely used as a flame retardant synergist in a number of household products, as a fining agent in glass manufacture, and as a catalyst in the manufacture of various types of polyester plastics. It does not induce point mutations in bacteria or mammalian cells, but is able to induce chromosomal aberrations (CA) in cultured cells in vitro. Although no CA or micronuclei (MN) have been induced after acute oral dosing of mice, repeated oral dosing for 14 or 21 days resulted in increased CA in one report, but did not result in increased MN in another. In order to further investigate its in vivo genotoxicity, Sb2O3 was dosed orally to groups of rats for 21 days at 250, 500 and 1000 mg/kg day. There were no clinical signs of toxicity in the Sb2O3-exposed animals except for some reductions in body-weight gain in the top dose group. Toxicokinetic measurements in a separate study confirmed bone-marrow exposure, and at higher levels than would have been achieved by single oral dosing. Large numbers of cells were scored for CA (600 metaphases/sex group) and MN (12,000 PCE/sex group) but frequencies of CA or MN in Sb2O3-treated rats were very similar to controls, and not biologically or statistically different, at all doses. These results provide further indication that Sb2O3 is not genotoxic to the bone marrow of rodents after 21 days of oral administration at high doses close to the maximum tolerated dose.

High-energy X-ray powder diffraction and atomic-pair distribution-function studies of charged/discharged structures in carbon-hybridized Li2MnSiO4 nanoparticles as a cathode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Moriya, Maki; Miyahara, Masahiko; Hokazono, Mana; Sasaki, Hirokazu; Nemoto, Atsushi; Katayama, Shingo; Akimoto, Yuji; Hirano, Shin-ichi; Ren, Yang

2014-10-01

The stable cycling performance with a high discharge capacity of ∼190 mAh g-1 in a carbon-hybridized Li2MnSiO4 nanostructured powder has prompted an experimental investigation of the charged/discharged structures using synchrotron-based and laboratory-based X-rays and atomic-pair distribution-function (PDF) analyses. A novel method of in-situ spray pyrolysis of a precursor solution with glucose as a carbon source enabled the successful synthesis of the carbon-hybridized Li2MnSiO4 nanoparticles. The XRD patters of the discharged (lithiated) samples exhibit a long-range ordered structure characteristic of the (β) Li2MnSiO4 crystalline phase (space group Pmn21) which dissipates in the charged (delithiated) samples. However, upon discharging the long-range ordered structure recovers in each cycle. The disordered structure, according to the PDF analysis, is mainly due to local distortions of the MnO4 tetrahedra which show a mean Mn-O nearest neighbor distance shorter than that of the long-range ordered phase. These results corroborate the notion of the smaller Mn3+/Mn4+ ionic radii in the Li extracted phase versus the larger Mn2+ ionic radius in Li inserted phase. Thus Li extraction/insertion drives the fluctuation between the disordered and the long-range ordered structures.

Oxidation of Microcystins by Permanganate: pH and Temperature-Dependent Kinetics, Effect of DOM Characteristics, and Oxidation Mechanism Revisited.

PubMed

Kim, Min Sik; Lee, Hye-Jin; Lee, Ki-Myeong; Seo, Jiwon; Lee, Changha

2018-05-23

Oxidative degradation of six representative microcystins (MCs) (MC-RR, -LR, -YR, -LF, -LW and -LA) by potassium permanganate (KMnO4; Mn(VII)) was investigated, focusing on the temperature- and pH-dependent reaction kinetics, the effect of dissolved organic matter (DOM), and the oxidation mechanisms. Second-order rate constants for the reactions of the six MCs with Mn(VII) (kMn(VII),MC) were determined to be 160.4-520.1 M-1 s-1 (MC-RR > -LR  -YR > -LF  -LW > -LA) at pH 7.2 and 21°C. The kMn(VII),MC values exhibited activation energies ranging from 15.1 to 22.4 kJ mol-1. With increasing pH from 2 to 11, the kMn(VII),MC values decreased until pH 5, and plateaued over the pH range of 5-11, except for that of MC-YR (which increased at pH > 8). Species-specific second-order rate constants were calculated using predicted pKa values of MCs. The oxidation of MCs in natural waters was accurately predicted by the kinetic model using kMn(VII),MC and Mn(VII) exposure ([Mn(VII)]dt) values. Among different characteristics of DOM in natural waters, UV254, SUVA254, and the abundance of humic-like substances characterized by fluorescence spectroscopy exhibited good correlation with [Mn(VII)]dt. A thorough product study of MC-LR oxidation by Mn(VII) was performed using liquid chromatography-mass spectrometry.

Fe and Mn removal from mining drainage using goaf filling materials obtained from coal mining process.

PubMed

Zhang, Liping; Chen, Aolei; Qu, Hongbin; Xu, Shouqiang; Zhang, Xue; He, Xuwen

2015-01-01

Coal gangue, sandy soil and clay (mass ratio 45:4:1) as goaf filling materials acquired from coal mining processes were applied to remove Fe and Mn effectively from mining drainage. The results of an adsorption kinetic study showed that the Fe adsorption equation was y=21.454y+8.4712, R2=0.9924 and the Mn adsorption equation was y=7.5409x+0.905, R2=0.9957. Meanwhile, the goaf filling materials had low desorption capacity (Fe 6.765 μg/g, Mn 1.52 μg/g) and desorption ratio (Fe 8.98%, Mn 11.04%). Experiments demonstrated that Fe and Mn from mining drainage could be removed stably at a flow rate of 1.2 L/min, Fe inlet concentration of less than 40 mg/L, Mn inlet concentration of less than 2 mg/L and neutral or alkaline conditions. During a procedure of continuous experiments, the effluent quality could meet the requirement of the 'Code for Engineering Design of Sewage Regeneration-GB503352-2002'. A real-application project using goaf filling materials to treat mining drainage in Shendong coal mine showed that the average cost per ton of mining drainage was about 0.55 RMB, which could bring about considerable economic benefit for coal mining enterprises.

Effect of Iron Impurity on the Phase Composition, Structure and Properties of Magnesium Alloys Containing Manganese and Aluminum

NASA Astrophysics Data System (ADS)

Volkova, E. F.

2017-07-01

Results of a study of the interaction between iron impurity and manganese and aluminum alloying elements during formation of phase composition in alloys of the Mg - Mn, Mg - Al, Mg - Al - Mn, and Mg - Al - Zn - Mn systems are presented. It is proved that this interaction results in introduction of Fe into the intermetallic phase. The phase compositions of model magnesium alloys and commercial alloys MA2-1 and MA5 are studied. It is shown that both manganese and aluminum may bind the iron impurity into phases. Composite Fe-containing intermetallic phases of different compositions influence differently the corrosion resistance of magnesium alloys.

Preparation and Characterization of the Binary Group 13 Azides M(N3)3 and M(N3)3’CH3CN (M = Ga, In, TI), [Ga(N3)5](2-), and [M(N3)6](3-) (M = In, TI) (Preprint)

DTIC Science & Technology

2011-05-24

semiconductor and optoelectronic applications. Although most of these efforts were devoted to gallium azides, aluminium and indium azides were also...their usefulness for semiconductor and optoelectronic applications. Although most of these efforts were devoted to gallium azides,[20,21] aluminium and...57(1) N(7) -152(5) 6417(2) 7317(2) 54(1) N(8) 20(5) 6903(2) 7687(2) 48(1) N(9) 148(4) 7388(3) 8011 (3) 80(2) P(1) 4132(1) 6289(1) 9090(1) 30(1

A New Reactive FMIPv6 Mechanism for Minimizing Packet Loss

NASA Astrophysics Data System (ADS)

Kim, Pyungsoo

This paper considers a new reactive fast handover MIPv6 (FMIPv6) mechanism to minimize packet loss of the existing mechanism. The primary idea of the proposed reactive FMIPv6 mechanism is that the serving access router buffers packets toward the mobile node (MN) as soon as the link layer between MN and serving base station is disconnected. To implement the proposed mechanism, the router discovery message exchanged between MN and serving access router is extended. In addition, the IEEE 802.21 Media Independent Handover Function event service message is defined newly. Through analytic performance evaluation and experiments, the proposed reactive FMIPv6 mechanism can be shown to minimize packet loss much than the existing mechanism.

21. Photographic copy of blueprints and plans (from the originals ...

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

21. Photographic copy of blueprints and plans (from the originals in possession of Detroit District, U.S. Army Corps of Engineers, Duluth, Minnesota). North pier of Duluth Canal, 1899, crib no. 17 - Duluth Ship Canal, North Pier, North end of Minnesota Point at Canal Park, Duluth, St. Louis County, MN

21 CFR 184.1446 - Manganese chloride.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Manganese chloride. 184.1446 Section 184.1446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Specific Substances Affirmed as GRAS § 184.1446 Manganese chloride. (a) Manganese chloride (MnCl2·4H2O, CAS...

Well-Coupled Nanohybrids Obtained by Component-Controlled Synthesis and in Situ Integration of Mn xPd y Nanocrystals on Vulcan Carbon for Electrocatalytic Oxygen Reduction.

PubMed

Lu, Yanan; Zhao, Shulin; Yang, Rui; Xu, Dongdong; Yang, Jing; Lin, Yue; Shi, Nai-En; Dai, Zhihui; Bao, Jianchun; Han, Min

2018-03-07

Development of cheap, highly active, and robust bimetallic nanocrystal (NC)-based nanohybrid (NH) electrocatalysts for oxygen reduction reaction (ORR) is helpful for advancing fuel cells or other renewable energy technologies. Here, four kinds of well-coupled Mn x Pd y (MnPd 3 , MnPd-Pd, Mn 2 Pd 3 , Mn 2 Pd 3 -Mn 11 Pd 21 )/C NHs have been synthesized by in situ integration of Mn x Pd y NCs with variable component ratios on pretreated Vulcan XC-72 C using the solvothermal method accompanied with annealing under Ar/H 2 atmosphere and used as electrocatalysts for ORR. Among them, the MnPd 3 /C NHs possess the unique "half-embedded and half-encapsulated" interfaces and exhibit the highest catalytic activity, which can compete with some currently reported non-Pt catalysts (e.g., Ag-Co nanoalloys, Pd 2 NiAg NCs, PdCo/N-doped porous C, G-Cu 3 Pd nanocomposites, etc.), and close to commercial Pt/C. Electrocatalytic dynamic measurements disclose that their ORR mechanism abides by the direct 4e - pathway. Moreover, their durability and methanol-tolerant capability are much higher than that of Pt/C. As revealed by spectroscopic and electrochemical analyses, the excellent catalytic performance of MnPd 3 /C NHs results from the proper component ratio of Mn and Pd and the strong interplay of their constituents, which not only facilitate to optimize the d-band center or the electronic structure of Pd but also induce the phase transformation of MnPd 3 active components and enhance their conductivity or interfacial electron transfer dynamics. This work demonstrates that MnPd 3 /C NHs are promising methanol-tolerant cathode electrocatalysts that may be employed in fuel cells or other renewable energy option.

Cubic Mn2Ga Thin Films: Crossing the Spin Gap with Ruthenium

NASA Astrophysics Data System (ADS)

Kurt, H.; Rode, K.; Stamenov, P.; Venkatesan, M.; Lau, Y.-C.; Fonda, E.; Coey, J. M. D.

2014-01-01

Cubic Mn2Ga films with the half-Heusler C1b structure are grown on V (001) epitaxial films. The phase is a soft ferrimagnet, with Curie temperature TC = 225 K and magnetization Ms=280 kA m-1, equivalent to 1.65μB per formula. Adding ruthenium leads to an increase of TC up to 550 K in cubic Mn2RuxGa films with x = 0.33 and a collapse of the net magnetization. The anomalous Hall effect changes sign at x = 0.5, where the sign of the magnetization changes and the magnetic easy direction flips from in plane to perpendicular to the film. The Mn2Ru0.5Ga compound with a valence electron count of 21 is identified as a zero-moment ferrimagnet with high spin polarization, which shows evidence of half-metallicity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thakur, Priya, E-mail: priyathakur1191@gmail.com; Thakur, Anjna; Yadav, Kamlesh, E-mail: kamlesh.yadav001@gmail.com

In this paper(LaMnO{sub 3}){sub 1−x}/ (TiO{sub 2}) {sub x} (where x = 0.0, 0.1, 0.2, 0.3 and 0.4) nanocomposite are prepared by mixing the LaMnO{sub 3} and TiO{sub 2} (Sigma Chemicals, particle size ∼21 nm) nanoparticle in appropriate ratio. These samples were characterized by using FESEM, EDS and FTIR to study the optical properties. Field Emission Scanning Electron Microscopy (FESEM) image of pure LaMnO{sub 3} sample shows that the uniform particle size distribution is observed. The average particle size of the LaMnO{sub 3} nanoparticles is 43 nm. The crystallite size increases from 16-24 nm with increasing the weight percentage of TiO{sub 2} inmore » LaMnO{sub 3}/TiO{sub 2} nanocomposite up to x = 0.4. The Fourier transform infrared spectroscopy (FTIR) spectra show that the absorption peaks appear at 450 cm{sup −1} and 491 cm{sup −1} which represent the Mn-O bending and Ti-O stretching mode respectively. The broadening of these peaks with increasing the concentration of TiO{sub 2} is also observed. It gives an evidence for the formation of metal oxygen bond. The absorption band at 600 cm{sup −1} corresponds to the stretching mode, which indicates the pervoskite phase present in the sample. The values of band gap are found 2.1, 1.9, 1.5, 1.3 and 1.2 eV for the x = 0.0, 0.1, 0.2, 0.3, and 0.4 respectively. Thus, the decrease in band gap and increase in refractive index with increasing concentration of TiO{sub 2} has been observed. These prepared nanocomposites can be used in the energy applications, to make the electrical devices and as a catalyst for photocatalytic processes e.g. hydrogenation.« less

Cosmogenic radionuclides in stone meteorites

NASA Technical Reports Server (NTRS)

Cressy, P. J., Jr.

1976-01-01

This document presents the techniques and compilation of results of cosmogenic Al-26 measurements at Goddard Space Flight Center on 91 samples of 76 stone meteorites. Short-lived radionuclides, including Na-22, Sc-46, Mn-54, and Co-60, were measured in 13 of these meteorites. About one-third of these data has not previously been published. The results are discussed briefly in terms of (1) depletion of Al-26 and natural potassium due to weathering, (2) possible exposure of several chondrites to an unusually high cosmic-ray flux, (3) comparison of Al-26, Na-22, Sc-46, and Mn5-54 in chondrites with the spallation Ne-22/Ne-21 ratio as a shielding indicator, and (4) comparison of (Al-26)-(Ne-22)/Ne-21 data for achondrite classes with the chondrite trend.

Chromosome painting reveals specific patterns of chromosome occurrence in mitomycin C- and diethylstilboestrol-induced micronuclei.

PubMed

Fauth, E; Scherthan, H; Zankl, H

2000-11-01

Cultures of human blood lymphocytes from three subjects were incubated with the clastogen mitomycin C (MMC, 500 ng/ml) and the aneugen diethylstilboestrol (DES, 80 microM) 23 h before harvesting, to induce formation of micronuclei (MN) and numerical and structural alterations in metaphase chromosomes. We used fluorescence in situ hybridization (FISH) with painting probes for all human chromosomes to determine which chromosomes had contributed material to the induced MN. MMC treatment induced an approximately 18-fold increase in MN and led to a significant increase in hypodiploidy and structural chromosome aberrations in metaphase preparations. Undercondensation of pericentromeric heterochromatin of chromosomes 9 and 1 occurred in 20-75% of metaphases and FISH disclosed an abundance of material from these chromosomes in induced MN (62-69% from chromosome 9 and 7-12% from chromosome 1). DES treatment of lymphocytes induced a seven-fold increase in MN frequency and four-fold increase in the frequency of numerical aberrations; structural aberrations were not significantly increased. FISH analysis showed that material from all chromosomes was present in DES-induced MN, with material from chromosome 1 present in 16% of MN and material from each other chromosomes being present in 2-10% of MN. Material from chromosomes 14, 19 and 21 was significantly more frequent material from chromosome Y significantly less frequent in DES-treated cells than in controls. The findings of the MMC studies indicate that the heterochromatin block of chromosome 9 is a specific target for MMC-induced undercondensation, which induces a preferential occurrence of chromosome 9 material in MN. DES, in contrast, does not trigger heterochromatin decondensation and fails to induce such a significant appearance of material of particular chromosomes in MN.

Influence of biodegradable polymer coatings on corrosion, cytocompatibility and cell functionality of Mg-2.0Zn-0.98Mn magnesium alloy.

PubMed

Witecka, Agnieszka; Yamamoto, Akiko; Idaszek, Joanna; Chlanda, Adrian; Święszkowski, Wojciech

2016-08-01

Four kinds of biodegradable polymers were employed to prepare bioresorbable coatings on Mg-2.0Zn-0.98Mn (ZM21) alloy to understand the relationship between polymer characteristics, protective effects on substrate corrosion, cytocompatibility and cell functionality. Poly-l-lactide (PLLA), poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(lactic-co-glycolic) acid (PLGA) was spin-coated on ZM21, obtaining a smooth, non-porous coating less than 0.5μm in thickness. Polymer coating characterization, a degradation study, and biocompatibility evaluations were performed. After 4 w of immersion into cell culture medium, degradation of PLGA and PLLA coatings were confirmed by ATR-FTIR observation. The coatings of PLLA, PHB and PHBV, which have lower water permeability and slower degradation than PLGA, provide better suppression of initial ZM21 degradation and faster promotion of human osteosarcoma cell growth and differentiation. Copyright © 2016 Elsevier B.V. All rights reserved.

Free metal ion depletion by "Good's" buffers. III. N-(2-acetamido)iminodiacetic acid, 2:1 complexes with zinc(II), cobalt(II), nickel(II), and copper(II); amide deprotonation by Zn(II), Co(II), and Cu(II).

PubMed

Lance, E A; Rhodes, C W; Nakon, R

1983-09-01

Potentiometric, visible, infrared, electron spin, and nuclear magnetic resonance studies of the complexation of N-(2-acetamido)iminodiacetic acid (H2ADA) by Ca(II), Mg(II), Mn(II), Zn(II), Co(II), Ni(II), and Cu(II) are reported. Ca(II) and Mg(II) were found not to form 2:1 ADA2- to M(II) complexes, while Mn(II), Cu(II), Ni(II), Zn(II), and Co(II) did form 2:1 metal chelates at or below physiological pH values. Co(II) and Zn(II), but not Cu(II), were found to induce stepwise deprotonation of the amide groups to form [M(H-1ADA)4-(2)]. Formation (affinity) constants for the various metal complexes are reported, and the probable structures of the various metal chelates in solution are discussed on the basis of various spectral data.

Speciation of Mn(II), Mn(VII) and total manganese in water and food samples by coprecipitation-atomic absorption spectrometry combination.

PubMed

Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

2010-01-15

A speciation procedure based on the coprecipitation of manganese(II) with zirconium(IV) hydroxide has been developed for the investigation of levels of manganese species. The determination of manganese levels was performed by flame atomic absorption spectrometry (FAAS). Total manganese was determined after the reduction of Mn(VII) to Mn(II) by ascorbic acid. The analytical parameters including pH, amount of zirconium(IV), sample volume, etc., were investigated for the quantitative recoveries of manganese(II). The effects of matrix ions were also examined. The recoveries for manganese(II) were in the range of 95-98%. Preconcentration factor was calculated as 50. The detection limit for the analyte ions based on 3 sigma (n=21) was 0.75 microg L(-1) for Mn(II). The relative standard deviation was found to be lower than 7%. The validation of the presented procedure was performed by analysis of certified reference material having different matrices, NIST SRM 1515 (Apple Leaves) and NIST SRM 1568a (Rice Flour). The procedure was successfully applied to natural waters and food samples.

Ultrasound-guided hydrodissection decreases gliding resistance of the median nerve within the carpal tunnel.

PubMed

Evers, Stefanie; Thoreson, Andrew R; Smith, Jay; Zhao, Chunfeng; Geske, Jennifer R; Amadio, Peter C

2018-01-01

The aim of this study was to assess alterations in median nerve (MN) biomechanics within the carpal tunnel resulting from ultrasound-guided hydrodissection in a cadaveric model. Twelve fresh frozen human cadaver hands were used. MN gliding resistance was measured at baseline and posthydrodissection, by pulling the nerve proximally and then returning it to the origin. Six specimens were treated with hydrodissection, and 6 were used as controls. In the hydrodissection group there was a significant reduction in mean peak gliding resistance of 92.9 ± 34.8 mN between baseline and immediately posthydrodissection (21.4% ± 10.5%; P = 0.001). No significant reduction between baseline and the second cycle occurred in the control group: 9.6 ± 29.8 mN (0.4% ± 5.3%; P = 0.467). Hydrodissection can decrease the gliding resistance of the MN within the carpal tunnel, at least in wrists unaffected by carpal tunnel syndrome. A clinical trial of hydrodissection seems justified. Muscle Nerve 57: 25-32, 2018. © 2017 Wiley Periodicals, Inc.

The non-resonant kink modes triggering strong sawtooth-like crashes in the EAST tokamak

NASA Astrophysics Data System (ADS)

Li, Erzhong; Igochine, V.; Dumbrajs, O.; Xu, L.; Chen, K.; Shi, T.; Hu, L.

2014-12-01

Evolution of the safety factor (q) profile during L-H transitions in the Experimental Advanced Superconducting Tokamak (EAST) was accompanied by strong core crashes prior to regular sawtooth behavior. These crashes appeared in the absence of q = 1 (q is the safety factor) rational surface inside the plasma. Analysis indicates that the m/n = 2/1 tearing mode is destabilized and phase-locked with the m/n = 1/1 non-resonant kink mode (the q = 1 rational surface is absent) due to the self-consistent evolution of plasma profiles as the L-H transition occurs (m and n are the poloidal and toroidal mode numbers, respectively). The growing m/n = 1/1 mode destabilizes the m/n = 2/2 kink mode which eventually triggers the strong crash due to an anomalous heat conductivity, as predicted by the transport model of stochastic magnetic fields using experimental parameters. It is also shown that the magnetic topology changes with the amplitude of m/n = 2/2 mode and the value of center safety factor in a reasonable range.

Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x AB2-type metal hydride alloys for electrochemical storage application: Part 1. Structural characteristics

NASA Astrophysics Data System (ADS)

Bendersky, L. A.; Wang, K.; Levin, I.; Newbury, D.; Young, K.; Chao, B.; Creuziger, A.

2012-11-01

The microstructures of a series of AB2-based metal hydride alloys (Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x) designed to have different fractions of non-Laves secondary phases were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, and electron backscatter diffraction. The results indicate that the alloys contain a majority of hydrogen storage Laves phases and a minority of fine-structured non-Laves phases. Formation of the phases is accomplished by dendritic growth of a hexagonal C14 Laves phase. The C14 phase is followed by either a peritectic solidification of a cubic C15 Laves phase (low Mn containing alloys) or a C14 phase of different composition (high Mn containing alloys), and finally a B2 phase formed in the interdendritic regions (IDR). The interdendritic regions may then undergo further solid-state transformation into Zr7Ni10-type, Zr9Ni11-type and TiNi-type phases. As the Mn content in the alloy increases, the fraction of the C14 phase increases, whereas the fraction of C15 decreases. In the IDRs when the alloy's Mn content increases the Zr9Ni11 phases and Zr7Ni10 phase fraction first increases and then decreases, while the TiNi-based phase fraction first increases and then stabilized at 0.02. IDR compositions can be generally expressed as (Ti,Zr,V,Cr,Mn,Co)50Ni50, which accounted for 7-10% of the overall alloy volume fraction.

Comparison of spontaneous and idoxuridine-induced micronuclei by chromosome painting.

PubMed

Fauth, E; Zankl, H

1999-04-06

Fluorescence in situ hybridisation (FISH) technique with chromosome specific library (CSL) DNA probes for all human chromosomes were used to study about 9000 micronuclei (MN) in normal and idoxuridine (IUdR)-treated lymphocyte cultures of female and male donors. In addition, MN rates and structural chromosome aberrations were scored in Giemsa-stained chromosome spreads of these cultures. IUdR treatment (40 microg/ml) induced on the average a 12-fold increase of the MN rate. Metaphase analysis revealed no distinct increase of chromosome breaks but a preferential decondensation at chromosome 9q12 (28-79%) and to a lower extend at 1q12 (8-21%). Application of FISH technique with CSL probes to one male and one female untreated proband showed that all human chromosomes except chromosome 12 (and to a striking high frequency chromosomes 9, X and Y) occurred in spontaneous MN. In cultures containing IUdR, the chromosomal spectrum found in MN was reduced to 10 chromosomes in the male and 13 in the female proband. Eight chromosomes (2, 6, 12, 13, 14, 15, 17 and 18) did not occur in MN of both probands. On the contrary chromosomes 1 and especially 9 were found much more frequently in the MN of IUdR-treated cultures than in MN of control cultures. DAPI-staining revealed heterochromatin signals in most of the IUdR-induced MN. In an additional study, spontaneous and IUdR-induced MN were investigated in lymphocytes of another female donor using CSL probes only for chromosomes 1, 6, 9, 15, 16 and X. The results confirmed the previous finding that chromosomes 1 and 9 occur very often in MN after IUdR-treatment. The results indicate that decondensation of heterochromatic regions on chromosomes 1 and 9 caused by IUdR treatment strongly correlates with MN formation by these chromosomes. Copyright 1999 Elsevier Science B.V.

Synthesis and characterization of single-phase Mn-doped ZnO

NASA Astrophysics Data System (ADS)

Chattopadhyay, S.; Dutta, S.; Banerjee, A.; Jana, D.; Bandyopadhyay, S.; Chattopadhyay, S.; Sarkar, A.

2009-05-01

Different samples of Zn 1-xMn xO series have been prepared using conventional solid-state sintering method. We identified up to what extent doping will enable us to synthesize single-phase polycrystalline Mn-doped ZnO sample, which is one of the prerequisites for dilute magnetic semiconductor, and we have analyzed its some other physical aspects. In synthesizing the samples, proportion of Mn varies from 1 to 5 at%. However, the milling time varied (6, 12, 24, 48 and 96 h) only for 2 at% Mn-doped samples while for other samples (1, 3, 4 and 5 at% Mn doped) the milling time has been fixed to 96 h. Room-temperature X-ray diffraction (XRD) data reveal that all of the prepared samples up to 3 at% of Mn doping exhibit wurtzite-type structure, and no segregation of Mn and/or its oxides has been found. The 4 at% Mn-doped samples show a weak peak of ZnMn 2O 4 apart from the other usual peaks of ZnO and the intensity of this impurity peak has been further increased for 5 at% of Mn doping. So beyond 3 at% doping, single-phase behavior is destroyed. Band gap for all the 2 at% Mn-doped samples has been estimated to be between 3.21 and 3.19 eV and the reason for this low band gap values has been explained through the grain boundary trapping model. The room-temperature resistivity measurement shows an increase of resistivity up to 48 h of milling and with further milling it saturates. The defect state of these samples has been investigated using the positron annihilation lifetime (PAL) spectroscopy technique. Here all the relevant lifetime parameters of positron i.e. free annihilation ( τ1) at defect site ( τ2) and average ( τav) increases with milling time.

Redox Deposition of Nanoscale Metal Oxides on Carbon for Next-Generation Electrochemical Capacitors

DTIC Science & Technology

2013-01-01

Nanoscale Metal Oxides Sassin et al. Redox Deposition Approaches to Nanoscale Coatings of Metal Oxides Manganese Oxides. Permanganate (MnO4 ) is a versa...scalability of the permanganate carbon redox reaction for generating MnOx coatings that store charge.21 The initial study per- formed on planar graphite...the carbon surface from the aqueous permanganate solu- tion (pH∼5),29,35 evidenced by a sharp increase in solution pH and a decrease in solution

Factors Influencing the Microstructure and Mechanical Properties of Ultra Low Carbon Bainitic 100 Tungsten Inert Gas Multipass Weldments

DTIC Science & Technology

1992-09-01

Optical macrograph of flat-etched sample 75B3-8 ........................ 30 Figure 4.15 Constitutional supercooling in alloy solidification ... alloying elements such as Mn, Mo, Ni and Cr are added to increase the strength and hardenability of the steel. However, substantial limitations on...0.9 Carbon Equivalent CE = C + Mn + Si + Ni + Cu + Cr + Mo + V 6 15 5 Figure 2.1 Graville Diagram (Blicharski et al, 1989, p.318) 3 B. ULTRA LOW

Nanostructured LiMn2O4 composite as high-rate cathode for high performance aqueous Li-ion hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Lina; Zhai, Wei; Chen, Long; Li, Deping; Ma, Xiaoxin; Ai, Qing; Xu, Xiaoyan; Hou, Guangmei; Zhang, Lin; Feng, Jinkui; Si, Pengchao; Ci, Lijie

2018-07-01

Nanostructured spinel LiMn2O4 and super P composite with much enhanced electrochemical performance especially ultrahigh rate capability as the cathode for aqueous hybrid supercapacitors is synthesized by ball milling commercial LiMn2O4 particles together with super P. The as-prepared composite delivers a high capacitance of 306 F g-1 at the current density of 1 A g-1 and superb rate ability of 228.6 F g-1 at 40 A g-1 in 1 M Li2SO4 aqueous electrolyte. The capacitance of the nanostructured composite is 3.5 times higher than that of pristine LiMn2O4 even being charged and discharged 80 times faster. The excellent performances are ascribed to the nanosized LiMn2O4 well dispersed into the conductive carbon matrix. LiMn2O4 and super P composite//active carbon hybrid supercapacitor is assembled and the energy density can reach up to 21.58 Wh kg-1 at 293.16 W kg-1 and 13 Wh kg-1 at 5200 W kg-1. The hybrid device also shows an excellent cycling performance, which retains 85% of the initial capacitance after 4500 cycles. This work provides an effectively facile way to produce high performance LiMn2O4-based cathodes for hybrid suercapacitors in practical applications.

Chemically synthesis and characterization of MnS thin films by SILAR method

NASA Astrophysics Data System (ADS)

Yıldırım, M. Ali; Yıldırım, Sümeyra Tuna; Cavanmirza, İlke; Ateş, Aytunç

2016-03-01

MnS thin films were synthesized on glass substrates using SILAR method. The film thickness effect on structural, morphological, optical and electrical properties of the films was investigated. The X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) studies showed that all the films exhibited polycrystalline nature with β-MnS structure and were covered well on glass substrates. The bandgap and resistivity values of the films decreased from 3.39 eV to 2.92 eV and from 11.84 × 106 to 2.21 × 105 Ω-cm as the film thickness increased from 180 to 350 nm, respectively. The refractive index (n) and dielectric constants (ɛo, ɛ∞) values were calculated.

Radial elemental and phase separation in Ni-Mn-Ga glass-coated microwires

NASA Astrophysics Data System (ADS)

Shevyrtalov, S.; Zhukov, A.; Medvedeva, S.; Lyatun, I.; Zhukova, V.; Rodionova, V.

2018-05-01

In this manuscript, radial elemental and phase separation in Ni-Mn-Ga glass-coated microwires with high excess Ni as a result of high-temperature annealing was observed. Partial manganese evaporation from the outer part of the metallic nucleus and glass melting results in the formation of manganese oxide at the surface. The lack of manganese due to its evaporation induces Ni3Ga formation in the intermediate part, while in the middle part of the metallic nucleus, the residual L21 phase with an average chemical composition of Ni60Mn9Ga31 remains. The layered structure exhibits soft ferromagnetic behavior below 270 K. The results were discussed taking into account the chemical composition, arising internal stresses, recrystallization, and atomic ordering.

Cu-Mn-Fe alloys and Mn-rich amphiboles in ancient copper slags from the Jabal Samran area, Saudi Arabia: With synopsis on chemistry of Fe-Mn(III) oxyhydroxides in alteration zones

NASA Astrophysics Data System (ADS)

Surour, Adel A.

2015-01-01

In the Jabal Samran area (western Saudi Arabia), secondary copper mineralization in a NE-trending shear zone in which the arc metavolcanic host rocks (dacite-rhyodacite) show conjugate fractures and extensive hydrothermal alteration and bleaching. The zones contain frequent Fe-Mn(III) oxyhydroxides (FeOH-MnOH) that resulted from oxidation of pyrite and Mn-bearing silicates. In the bleached part, the groundmass is represented by Fe-bearing interstratified illite-smectite with up to 4.02 wt% FeOt. FeOH-MnOH are pre-weathering phases formed by hydrothermal alteration in a submarine environment prior to uplifting. Five varieties of FeOH are distinguished, four of them are exclusively hydrothermal with ∼20 wt% H2O whereas the fifth contains ∼31-33 wt% H2O and might represent reworking of earlier hydrothermal FeOH phases by weathering. FeOH fills thin fractures in the form of veinlets and crenulated laminae or as a pseudomorph for pyrite, goethite and finally ferrihydrite, and this oxyhydroxide is characterized by positive correlation of Fe2O3 with SiO2 and Al2O3. On the other hand, MOH shows positive correlation between MnO2 and Al2O3 whereas it is negative between Fe2O3 and SiO2. Paratacamite is the most common secondary copper mineral that fills fractures and post-dates FeOH and MnOH. It is believed that Cl- in the structure of paratacamite represents inherited marine storage rather than from surfacial evaporates or meteoric water. The mineralogy of slags suggests a complicated mineral assemblage that includes native Cu prills, synthetic spinifixed Mn-rich amphiboles with 16.73 wt% MnO, brown glass and Ca-Mn-Fe phase close to the olivine structure. EMPA indicate that the some Cu prills have either grey discontinuous boarder zone of S-rich Mn-Cu alloy (with up to 21.95 wt% S and 19.45 wt% Mn) or grey Cu-Mn-Fe alloy (with up to 15.9 wt% Cu, 39. 12 wt% Mn and 61.64 wt% Fe). Mn in the Cu prills is expelled inward as Cu-Mn-Fe alloy inclusions whereas S is expelled outward as S-rich Mn-Cu alloy crust. Remains in the Samran smelter sites suggest the use of charcoal as a source of energy, quartzite as a flux and an air-cooling technique was used.

CuMnOS Nanoflowers with Different Cu+/Cu2+ Ratios for the CO2-to-CH3OH and the CH3OH-to-H2 Redox Reactions

PubMed Central

Chen, Xiaoyun; Abdullah, Hairus; Kuo, Dong-Hau

2017-01-01

A conservative CO2-Methanol (CH3OH) regeneration cycle, to capture and reutilize the greenhouse gas of CO2 by aqueous hydrogenation for industry-useful CH3OH and to convert aqueous CH3OH solution by dehydrogenation for the clean energy of hydrogen (H2), is demonstrated at normal temperature and pressure (NTP) with two kinds of CuMnOS nanoflower catalysts. The [Cu+]-high CuMnOS led to a CH3OH yield of 21.1 mmol·g−1catal.·h−1 in the CuMnOS-CO2-H2O system and the other [Cu+]-low one had a H2 yield of 7.65 mmol·g−1catal.·h−1 in the CuMnOS-CH3OH-H2O system. The successful redox reactions at NTP rely on active lattice oxygen of CuMnOS catalysts and its charge (hole or electron) transfer ability between Cu+ and Cu2+. The CO2-hydrogenated CH3OH in aqueous solution is not only a fuel but also an ideal liquid hydrogen storage system for transportation application. PMID:28117456

CuMnOS Nanoflowers with Different Cu+/Cu2+ Ratios for the CO2-to-CH3OH and the CH3OH-to-H2 Redox Reactions

NASA Astrophysics Data System (ADS)

Chen, Xiaoyun; Abdullah, Hairus; Kuo, Dong-Hau

2017-01-01

A conservative CO2-Methanol (CH3OH) regeneration cycle, to capture and reutilize the greenhouse gas of CO2 by aqueous hydrogenation for industry-useful CH3OH and to convert aqueous CH3OH solution by dehydrogenation for the clean energy of hydrogen (H2), is demonstrated at normal temperature and pressure (NTP) with two kinds of CuMnOS nanoflower catalysts. The [Cu+]-high CuMnOS led to a CH3OH yield of 21.1 mmol·g-1catal.·h-1 in the CuMnOS-CO2-H2O system and the other [Cu+]-low one had a H2 yield of 7.65 mmol·g-1catal.·h-1 in the CuMnOS-CH3OH-H2O system. The successful redox reactions at NTP rely on active lattice oxygen of CuMnOS catalysts and its charge (hole or electron) transfer ability between Cu+ and Cu2+. The CO2-hydrogenated CH3OH in aqueous solution is not only a fuel but also an ideal liquid hydrogen storage system for transportation application.

CuMnOS Nanoflowers with Different Cu+/Cu2+ Ratios for the CO2-to-CH3OH and the CH3OH-to-H2 Redox Reactions.

PubMed

Chen, Xiaoyun; Abdullah, Hairus; Kuo, Dong-Hau

2017-01-24

A conservative CO 2 -Methanol (CH 3 OH) regeneration cycle, to capture and reutilize the greenhouse gas of CO 2 by aqueous hydrogenation for industry-useful CH 3 OH and to convert aqueous CH 3 OH solution by dehydrogenation for the clean energy of hydrogen (H 2 ), is demonstrated at normal temperature and pressure (NTP) with two kinds of CuMnOS nanoflower catalysts. The [Cu + ]-high CuMnOS led to a CH 3 OH yield of 21.1 mmol·g -1 catal.·h -1 in the CuMnOS-CO 2 -H 2 O system and the other [Cu + ]-low one had a H 2 yield of 7.65 mmol·g -1 catal.·h -1 in the CuMnOS-CH 3 OH-H 2 O system. The successful redox reactions at NTP rely on active lattice oxygen of CuMnOS catalysts and its charge (hole or electron) transfer ability between Cu + and Cu 2+ . The CO 2 -hydrogenated CH 3 OH in aqueous solution is not only a fuel but also an ideal liquid hydrogen storage system for transportation application.

Avian influenza H9N2 seroprevalence among poultry workers in Pune, India, 2010.

PubMed

Pawar, Shailesh D; Tandale, Babasaheb V; Raut, Chandrashekhar G; Parkhi, Saurabh S; Barde, Tanaji D; Gurav, Yogesh K; Kode, Sadhana S; Mishra, Akhilesh C

2012-01-01

Avian influenza (AI) H9N2 has been reported from poultry in India. A seroepidemiological study was undertaken among poultry workers to understand the prevalence of antibodies against AI H9N2 in Pune, Maharashtra, India. A total of 338 poultry workers were sampled. Serum samples were tested for presence of antibodies against AI H9N2 virus by hemagglutination inhibition (HI) and microneutralization (MN) assays. A total of 249 baseline sera from general population from Pune were tested for antibodies against AI H9N2 and were negative by HI assay using ≥40 cut-off antibody titre. Overall 21 subjects (21/338 = 6.2%) were positive for antibodies against AI H9N2 by either HI or MN assays using ≥40 cut-off antibody titre. A total of 4.7% and 3.8% poultry workers were positive for antibodies against AI H9N2 by HI and MN assay respectively using 40 as cut-off antibody titre. This is the first report of seroprevalence of antibodies against AI H9N2 among poultry workers in India.

Comparative analysis of lignin peroxidase and manganese peroxidase activity on coniferous and deciduous wood using ToF-SIMS.

PubMed

MacDonald, Jacqueline; Goacher, Robyn E; Abou-Zaid, Mamdouh; Master, Emma R

2016-09-01

White-rot fungi are distinguished by their ability to efficiently degrade lignin via lignin-modifying type II peroxidases, including manganese peroxidase (MnP) and lignin peroxidase (LiP). In the present study, time-of flight secondary ion mass spectrometry (ToF-SIMS) was used to evaluate lignin modification in three coniferous and three deciduous wood preparations following treatment with commercial preparations of LiP and MnP from two different white-rot fungi. Percent modification of lignin was calculated as a loss of intact methoxylated lignin over nonfunctionalized aromatic rings, which is consistent with oxidative cleavage of methoxy moieties within the lignin structure. Exposure to MnP resulted in greater modification of lignin in coniferous compared to deciduous wood (28 vs. 18 % modification of lignin); and greater modification of G-lignin compared to S-lignin within the deciduous wood samples (21 vs. 12 %). In contrast, exposure to LiP resulted in similar percent modification of lignin in all wood samples (21 vs 22 %), and of G- and S-lignin within the deciduous wood (22 vs. 23 %). These findings suggest that the selected MnP and LiP may particularly benefit delignification of coniferous and deciduous wood, respectively. Moreover, the current analysis further demonstrates the utility of ToF-SIMS for characterizing enzymatic modification of lignin in wood fibre along with potential advantages over UV and HPCL-MS detection of solubilized delignification products.

Purification and characterization of Mn-peroxidase from Musa paradisiaca (banana) stem juice.

PubMed

Yadav, Pratibha; Singh, V K; Yadav, Meera; Singh, Sunil Kumar; Yadava, Sudha; Yadav, K D S

2012-02-01

Mn-peroxidase (MnP), a biotechnologically important enzyme was purified for the first time from a plant source Musa paradisiaca (banana) stem, which is an agro-waste easily available after harvest of banana fruits. MnP was earlier purified only from the fungal sources. The enzyme was purified from stem juice by ultrafiltration and anion-exchange column chromatography on diethylamino ethylcellulose with 8-fold purification and purification yield of 65%. The enzyme gave a single protein band in SDS-PAGE corresponding to molecular mass 43 kDa. The Native-PAGE of the enzyme also gave a single protein band, confirming the purity of the enzyme. The UV/VIS spectrum of the purified enzyme differed from the other heme peroxidases, as the Soret band was shifted towards lower wavelength and the enzyme had an intense absorption band around 250 nm. The K(m) values using MnSO4 and H2O2 as the substrates of the purified enzyme were 21.0 and 9.5 microM, respectively. The calculated k(cat) value of the purified enzyme using Mn(II) as the substrate in 50 mM lactate buffer (pH 4.5) at 25 degrees C was 6.7s(-1), giving a k(cat)/K(m) value of 0.32 microM(-1)s(-1). The k(cat) value for the MnP-catalyzed reaction was found to be dependent of the Mn(III) chelator molecules malonate, lactate and oxalate, indicating that the enzyme oxidized chelated Mn(II) to Mn(III). The pH and temperature optima of the enzyme were 4.5 and 25 degrees C, respectively. The enzyme in combination with H2O2 liberated bromine and iodine in presence of KBr and KI respectively. All these enzymatic characteristics were similar to those of fungal MnP. The enzyme has the potential as a green brominating and iodinating agent in combination with KBr/KI and H2O2.

Common Polymorphisms in the Solute Carrier SLC30A10 are Associated With Blood Manganese and Neurological Function

PubMed Central

Kippler, Maria; Alhamdow, Ayman; Rahman, Syed Moshfiqur; Smith, Donald R.; Vahter, Marie; Lucchini, Roberto G.; Broberg, Karin

2016-01-01

Manganese (Mn) is an essential nutrient in humans, but excessive exposure to Mn may cause neurotoxicity. Despite homeostatic regulation, Mn concentrations in blood vary considerably among individuals. We evaluated if common single-nucleotide polymorphisms (SNPs) in SLC30A10, which likely encodes an Mn transporter, influence blood Mn concentrations and neurological function. We measured blood Mn concentrations by ICP-MS or atomic absorption spectroscopy and genotyped 2 SLC30A10 non-coding SNPs (rs2275707 and rs12064812) by TaqMan PCR in cohorts from Bangladesh (N = 406), the Argentinean Andes (N = 198), and Italy (N = 238). We also measured SLC30A10 expression in whole blood by TaqMan PCR in a sub-group (N = 101) from the Andean cohort, and neurological parameters (sway velocity and finger-tapping speed) in the Italian cohort. The rs2275707 variant allele was associated with increased Mn concentrations in the Andes (8%, P = .027) and Italy (10.6%, P = .012), but not as clear in Bangladesh (3.4%, P = .21; linear regression analysis adjusted for age, gender, and plasma ferritin). This allele was also associated with increased sway velocity (15%, P = .033; adjusted for age and sex) and reduced SLC30A10 expression (−24.6%, P = .029). In contrast, the rs12064812 variant homozygous genotype was associated with reduced Mn concentrations, particularly in the Italian cohort (−18.4%, P = .04), and increased finger-tapping speed (8.7%, P = .025). We show that common SNPs in SLC30A10 are associated with blood Mn concentrations in 3 unrelated cohorts and that their influence may be mediated by altered SLC30A10 expression. Moreover, the SNPs appeared to influence neurological functions independent of blood Mn concentrations, suggesting that SLC30A10 could regulate brain Mn levels. PMID:26628504

Thermoelectric properties of a Mn substituted synthetic tetrahedrite.

PubMed

Chetty, Raju; D S, Prem Kumar; Rogl, Gerda; Rogl, Peter; Bauer, Ernst; Michor, Herwig; Suwas, Satyam; Puchegger, Stephan; Giester, Gerald; Mallik, Ramesh Chandra

2015-01-21

Tetrahedrite compounds Cu(12-x)Mn(x)Sb4S13 (0 ≤x≤ 1.8) were prepared by solid state synthesis. A detailed crystal structure analysis of Cu10.6Mn1.4Sb4S13 was performed by single crystal X-ray diffraction (XRD) at 100, 200 and 300 K confirming the noncentrosymmetric structure (space group I4[combining macron]3m) of a tetrahedrite. The large atomic displacement parameter of the Cu2 atoms was described by splitting the 12e site into a partially and randomly occupied 24g site (Cu22) in addition to the regular 12e site (Cu21), suggesting a mix of dynamic and static off-plane Cu2 atom disorder. Rietveld powder XRD pattern and electron probe microanalysis revealed that all the Mn substituted samples showed a single tetrahedrite phase. The electrical resistivity increased with increasing Mn due to substitution of Mn(2+) at the Cu(1+) site. The positive Seebeck coefficient for all samples indicates that the dominant carriers are holes. Even though the thermal conductivity decreased as a function of increasing Mn, the thermoelectric figure of merit ZT decreased, because the decrease of the power factor is stronger than the decrease of the thermal conductivity. The maximum ZT = 0.76 at 623 K is obtained for Cu12Sb4S13. The coefficient of thermal expansion 13.5 ± 0.1 × 10(-6) K(-1) is obtained in the temperature range from 460 K to 670 K for Cu10.2Mn1.8Sb4S13. The Debye temperature, Θ(D) = 244 K for Cu10.2Mn1.8Sb4S13, was estimated from an evaluation of the elastic properties. The effective paramagnetic moment 7.45 μB/f.u. for Cu10.2Mn1.8Sb4S13 is fairly consistent with a high spin 3d(5) ground state of Mn.

Early Postnatal Manganese Exposure Causes Lasting Impairment of Selective and Focused Attention and Arousal Regulation in Adult Rats.

PubMed

Beaudin, Stephane A; Strupp, Barbara J; Strawderman, Myla; Smith, Donald R

2017-02-01

Studies in children and adolescents have associated early developmental manganese (Mn) exposure with inattention, impulsivity, hyperactivity, and oppositional behaviors, but causal inferences are precluded by the correlational nature of the data and generally limited control for potential confounders. To determine whether early postnatal oral Mn exposure causes lasting attentional and impulse control deficits in adulthood, and whether continued lifelong Mn exposure exacerbates these effects, using a rat model of environmental Mn exposure. Neonates were exposed orally to 0, 25 or 50 mg Mn/kg/day during early postnatal life (PND 1-21) or throughout life from PND 1 until the end of the study. In adulthood, the animals were tested on a series of learning and attention tasks using the five-choice serial reaction time task. Early postnatal Mn exposure caused lasting attentional dysfunction due to impairments in attentional preparedness, selective attention, and arousal regulation, whereas associative ability (learning) and impulse control were spared. The presence and severity of these deficits varied with the dose and duration of Mn exposure. This study is the first to show that developmental Mn exposure can cause lasting impairments in focused and selective attention and arousal regulation, and to identify the specific nature of the impairments. Given the importance of attention and arousal regulation in cognitive functioning, these findings substantiate concerns about the adverse effects of developmental Mn exposure in humans. Citation: Beaudin SA, Strupp BJ, Strawderman M, Smith DR. 2017. Early postnatal manganese exposure causes lasting impairment of selective and focused attention and arousal regulation in adult rats. Environ Health Perspect 125:230-237; http://dx.doi.org/10.1289/EHP258.

Early Postnatal Manganese Exposure Causes Lasting Impairment of Selective and Focused Attention and Arousal Regulation in Adult Rats

PubMed Central

Beaudin, Stephane A.; Strupp, Barbara J.; Strawderman, Myla; Smith, Donald R.

2016-01-01

Background: Studies in children and adolescents have associated early developmental manganese (Mn) exposure with inattention, impulsivity, hyperactivity, and oppositional behaviors, but causal inferences are precluded by the correlational nature of the data and generally limited control for potential confounders. Objectives: To determine whether early postnatal oral Mn exposure causes lasting attentional and impulse control deficits in adulthood, and whether continued lifelong Mn exposure exacerbates these effects, using a rat model of environmental Mn exposure. Methods: Neonates were exposed orally to 0, 25 or 50 mg Mn/kg/day during early postnatal life (PND 1–21) or throughout life from PND 1 until the end of the study. In adulthood, the animals were tested on a series of learning and attention tasks using the five-choice serial reaction time task. Results: Early postnatal Mn exposure caused lasting attentional dysfunction due to impairments in attentional preparedness, selective attention, and arousal regulation, whereas associative ability (learning) and impulse control were spared. The presence and severity of these deficits varied with the dose and duration of Mn exposure. Conclusions: This study is the first to show that developmental Mn exposure can cause lasting impairments in focused and selective attention and arousal regulation, and to identify the specific nature of the impairments. Given the importance of attention and arousal regulation in cognitive functioning, these findings substantiate concerns about the adverse effects of developmental Mn exposure in humans. Citation: Beaudin SA, Strupp BJ, Strawderman M, Smith DR. 2017. Early postnatal manganese exposure causes lasting impairment of selective and focused attention and arousal regulation in adult rats. Environ Health Perspect 125:230–237; http://dx.doi.org/10.1289/EHP258 PMID:27384154

Activation by divalent cations of a Ca2+-activated K+ channel from skeletal muscle membrane.

PubMed

Oberhauser, A; Alvarez, O; Latorre, R

1988-07-01

Several divalent cations were studied as agonists of a Ca2+-activated K+ channel obtained from rat muscle membranes and incorporated into planar lipid bilayers. The effect of these agonists on single-channel currents was tested in the absence and in the presence of Ca2+. Among the divalent cations that activate the channel, Ca2+ is the most effective, followed by Cd2+, Sr2+, Mn2+, Fe2+, and Co2+. Mg2+, Ni2+, Ba2+, Cu2+, Zn2+, Hg2+, and Sn2+ are ineffective. The voltage dependence of channel activation is the same for all the divalent cations. The time-averaged probability of the open state is a sigmoidal function of the divalent cation concentration. The sigmoidal curves are described by a dissociation constant K and a Hill coefficient N. The values of these parameters, measured at 80 mV are: N = 2.1, K = 4 X 10(-7) mMN for Ca2+; N = 3.0, K = 0.02 mMN for Cd2+; N = 1.45, K = 0.63 mMN for Sr2+; N = 1.7, K = 0.94 mMN for Mn2+; N = 1.1, K = 3.0 mMN for Fe2+; and N = 1.1 K = 4.35 mMN for Co2+. In the presence of Ca2+, the divalent cations Cd2+, Co2+, Mn2+, Ni2+, and Mg2+ are able to increase the apparent affinity of the channel for Ca2+ and they increase the Hill coefficient in a concentration-dependent fashion. These divalent cations are only effective when added to the cytoplasmic side of the channel. We suggest that these divalent cations can bind to the channel, unmasking new Ca2+ sites.

Inhibition of ATPase activity in rat synaptic plasma membranes by simultaneous exposure to metals.

PubMed

Carfagna, M A; Ponsler, G D; Muhoberac, B B

1996-03-08

Inhibition of Na+/K+-ATPase and Mg2+-ATPase activities by in vitro exposure to Cd2+, Pb2+ and Mn2+ was investigated in rat brain synaptic plasma membranes (SPMs). Cd2+ and Pb2+ produced a larger maximal inhibition of Na+/K+-ATPase than of Mg2+-ATPase activity. Metal concentrations causing 50% inhibition of Na+/K+-ATPase activity (IC50 values) were Cd2+ (0.6 microM) < Pb2+ (2.1 microM) < Mn2+ (approximately 3 mM), and the former two metals were substantially more potent in inhibiting SPM versus synaptosomal Na+/K+-ATPase. Dixon plots of SPM data indicated that equilibrium binding of metals occurs at sites causing enzyme inhibition. In addition, IC50 values for SPM K+-dependent p-nitrophenylphosphatase inhibition followed the same order and were Cd2+ (0.4 microM) < Pb2+ (1.2 microM) < Mn2+ (300 microM). Simultaneous exposure to the combinations Cd2+/Mn2+ or Pb2+/Mn2+ inhibited SPM Na+/K+-ATPase activity synergistically (i.e., greater than the sum of the metal-induced inhibitions assayed separately), while Cd2+/Pb2+ caused additive inhibition. Simultaneous exposure to Cd2+/Pb2+ antagonistically inhibited Mg2+-ATPase activity while Cd2+/Mn2+ or Pb2+/Mn2+ additively inhibited Mg2+-ATPase activity at low Mn2+ concentrations, but inhibited antagonistically at higher concentrations. The similar IC50 values for Cd2+ and Pb2+ versus Mn2+ inhibition of Na+/K+-ATPase and the pattern of inhibition/activation upon exposure to two metals simultaneously support similar modes of interaction of Cd2+ and Pb2+ with this enzyme, in agreement with their chemical reactivities.

Preparation and Properties of (YCa)(TiMn)O3−δ Ceramics Interconnect of Solid Oxide Fuel Cells

PubMed Central

Liou, Yi-Cheng; Tsai, Wen-Chou; Yen, Hao-Hsuan; Chang, Yung-Chia

2015-01-01

(YCa)(TiMn)O3–δ ceramics prepared using a reaction-sintering process were investigated. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. Y2Ti2O7 instead of YTiO3 formed when a mixture of Y2O3 and TiO2 with Y/Ti ratio 1/1 were sintered in air. Y2Ti2O7, YTiO2.085 and some unknown phases were detected in Y0.6Ca0.4Ti0.6Mn0.4O3–δ. Monophasic Y0.6Ca0.4Ti0.4Mn0.6O3–δ ceramics were obtained after 1400–1500 °C sintering. Dense Y0.6Ca0.4Ti0.4Mn0.6O3–δ with a density 4.69 g/cm3 was observed after 1500 °C/4 h sintering. Log σ for Y0.6Ca0.4Ti0.6Mn0.4O3–δ increased from –3.73 Scm–1 at 350 °C to –2.14 Scm–1 at 700 °C. Log σ for Y0.6Ca0.4Ti0.4Mn0.6O3–δ increased from –2.1 Scm–1 at 350 °C to –1.36 Scm–1 at 700 °C. Increasing Mn content decreased activation energy Ea and increased electrical conductivity. Reaction-sintering process is proved to be a simple and effective method to obtain (YCa)(TiMn)O3–δ ceramics for interconnects in solid oxide fuel cells. PMID:28793436

The blue supergiant MN18 and its bipolar circumstellar nebula

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.; Kniazev, A. Y.; Bestenlehner, J. M.; Bodensteiner, J.; Langer, N.; Greiner, J.; Grebel, E. K.; Berdnikov, L. N.; Beletsky, Y.

2015-11-01

We report the results of spectrophotometric observations of the massive star MN18 revealed via discovery of a bipolar nebula around it with the Spitzer Space Telescope. Using the optical spectrum obtained with the Southern African Large Telescope, we classify this star as B1 Ia. The evolved status of MN18 is supported by the detection of nitrogen overabundance in the nebula, which implies that it is composed of processed material ejected by the star. We analysed the spectrum of MN18 by using the code CMFGEN, obtaining a stellar effective temperature of ≈21 kK. The star is highly reddened, E(B - V) ≈ 2 mag. Adopting an absolute visual magnitude of MV = -6.8 ± 0.5 (typical of B1 supergiants), MN18 has a luminosity of log L/L⊙ ≈ 5.42 ± 0.30, a mass-loss rate of ≈(2.8-4.5) × 10- 7 M⊙ yr- 1, and resides at a distance of ≈5.6^{+1.5} _{-1.2} kpc. We discuss the origin of the nebula around MN18 and compare it with similar nebulae produced by other blue supergiants in the Galaxy (Sher 25, HD 168625, [SBW2007] 1) and the Large Magellanic Cloud (Sk-69°202). The nitrogen abundances in these nebulae imply that blue supergiants can produce them from the main-sequence stage up to the pre-supernova stage. We also present a K-band spectrum of the candidate luminous blue variable MN56 (encircled by a ring-like nebula) and report the discovery of an OB star at ≈17 arcsec from MN18. The possible membership of MN18 and the OB star of the star cluster Lynga 3 is discussed.

Fully epitaxial C1b-type NiMnSb half-Heusler alloy films for current-perpendicular-to-plane giant magnetoresistance devices with a Ag spacer

PubMed Central

Wen, Zhenchao; Kubota, Takahide; Yamamoto, Tatsuya; Takanashi, Koki

2015-01-01

Remarkable magnetic and spin-dependent transport properties arise from well-designed spintronic materials and heterostructures. Half-metallic Heusler alloys with high spin polarization exhibit properties that are particularly advantageous for the development of high-performance spintronic devices. Here, we report fully (001)-epitaxial growth of a high-quality half-metallic NiMnSb half-Heusler alloy films, and their application to current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices with Ag spacer layers. Fully (001)-oriented NiMnSb epitaxial films with very flat surface and high magnetization were prepared on Cr/Ag-buffered MgO(001) single crystalline substrates by changing the substrate temperature. Epitaxial CPP-GMR devices using the NiMnSb films and a Ag spacer were fabricated, and room-temperature (RT) CPP-GMR ratios for the C1b-type half-Heusler alloy were determined for the first time. A CPP-GMR ratio of 8% (21%) at RT (4.2 K) was achieved in the fully epitaxial NiMnSb/Ag/NiMnSb structures. Furthermore, negative anisotropic magnetoresistance (AMR) ratio and small discrepancy of the AMR amplitudes between RT and 10 K were observed in a single epitaxial NiMnSb film, indicating robust bulk half metallicity against thermal fluctuation in the half-Heusler compound. The modest CPP-GMR ratios could be attributed to interface effects between NiMnSb and Ag. This work provides a pathway for engineering a new class of ordered alloy materials with particular emphasis on spintronics. PMID:26672482

Cobalt doped CuMnOx catalysts for the preferential oxidation of carbon monoxide

NASA Astrophysics Data System (ADS)

Dey, Subhashish; Dhal, Ganesh Chandra; Mohan, Devendra; Prasad, Ram; Gupta, Rajeev Nayan

2018-05-01

Carbon monoxide (CO) is a poisonous gas, recognized as a silent killer for the 21st century. It is produced from the partial oxidation of carbon containing compounds. The catalytic oxidation of CO receives a huge attention due to its applications in different fields. In the present work, hopcalite (CuMnOx) catalysts were synthesized using a co-precipitation method for CO oxidation purposes. Also, it was doped with the cobalt by varying concentration from 1 to 5wt%. It was observed that the addition of cobalt into the CuMnOx catalyst (by the deposition-precipitation method) improved the catalytic performance for the low-temperature CO oxidation. CuMnOx catalyst doped with 3wt% of cobalt exhibited most active performance and showed the highest activity than other cobalt concentrations. Different analytical tools (i.e. XRD, FTIR, BET, XPS and SEM-EDX) were used to characterize the as-synthesized catalysts. It was expected that the introduction of cobalt will introduce new active sites into the CuMnOx catalyst that are associated with the cobalt nano-particles. The order of calcination strategies based on the activity for cobalt doped CuMnOx catalysts was observed as: Reactive calcinations (RC) > flowing air > stagnant air. Therefore, RC (4.5% CO in air) route can be recommended for the synthesis of highly active catalysts. The catalytic activity of doped CuMnOx catalysts toward CO oxidation shows a correlation among average oxidation number of Mn and the position and the nature of the doped cobalt cation.

Distinct Functions of CCAAT Enhancer-binding Protein Isoforms in the Regulation of Manganese Superoxide Dismutase during Interleukin-1β Stimulation*

PubMed Central

Qiu, Xiaolei; Aiken, Kimberly J.; Chokas, Ann L.; Beachy, Dawn E.; Nick, Harry S.

2008-01-01

The mitochondrial antioxidant enzyme manganese superoxide dismutase (Mn-SOD) is crucial in maintaining cellular and organismal homeostasis. Mn-SOD expression is tightly regulated in a manner that synchronizes its cytoprotective functions during inflammatory challenges. Induction of Mn-SOD gene expression by the proinflammatory cytokine IL-1β is mediated through a complex intronic enhancer element. To identify and characterize the transcription factors required for Mn-SOD enhancer function, a yeast one-hybrid assay was utilized, and two CCAAT enhancer-binding protein (C/EBP) members, C/EBP β and C/EBP δ, were identified. These two transcription factors responded to IL-1β treatment with distinct expression profiles, different temporal yet inducible interactions with the endogenous Mn-SOD enhancer, and also opposite effects on Mn-SOD transcription. C/EBP β is expressed as three isoforms, LAP* (liver-activating protein), LAP, and LIP (liver-inhibitory protein). Our functional analysis demonstrated that only the full-length C/EBP β/LAP* served as a true activator for Mn-SOD, whereas LAP, LIP, and C/EBP δ functioned as potential repressors. Finally, our systematic mutagenesis of the unique N-terminal 21 amino acids further solidified the importance of LAP* in the induction of Mn-SOD and emphasized the crucial role of this isoform. Our data demonstrating the physiological relevance of the N-terminal peptide also provide a rationale for revisiting the role of LAP* in the regulation of other genes and in pathways such as lipogenesis and development. PMID:18559338

CotA, a Multicopper Oxidase from Bacillus pumilus WH4, Exhibits Manganese-Oxidase Activity

PubMed Central

Su, Jianmei; Bao, Peng; Bai, Tenglong; Deng, Lin; Wu, Hui; Liu, Fan; He, Jin

2013-01-01

Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85±1.17 mM, 3.01×10−6±0.21 M·min−1 and 0.32±0.02 s−1, respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a potential biocatalyst for Mn(II) removal. PMID:23577125

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanjeewa, Liurukara. D.; McGuire, Michael A.; McMillen, Colin D.

We synthesized new complex manganese vanadate materials as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. We grew one compound, Mn 5(VO 4) 2(OH) 4, from Mn 2O 3 and V 2O 5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn 6O(VO 4) 2(OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn 5(VO 4) 2(OH) 4: C2/m, Z = 2, a = 9.6568(9) Å, b = 9.5627(9) Å, c = 5.4139(6) Å, β = 98.529(8)°; Mn 6O(VOmore » 4) 2(OH): P21/m, Z = 2, a = 8.9363(12) Å, b = 6.4678(8) Å, c = 10.4478(13) Å, β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn 5(VO 4) 2(OH) 4 possesses complex honeycomb-type Mn–O layers, built from edge-sharing [MnO 6] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn 6O(VO 4) 2(OH) presents a more complicated structure with both octahedral [MnO 6] and trigonal bipyramidal [MnO 5] units. A different pattern of planar honeycomb sheets are formed by edge-shared [MnO6] octahedra, and these sublattices are connected through edge-shared dimers of [MnO 5] trigonal bipyramids to form corrugated sheets. Vanadate groups again condense the sheets into a three-dimensional framework. Infrared and Raman spectroscopies indicated the presence of OH groups and displayed characteristic Raman scattering due to vanadate groups. Furthermore, temperature-dependent magnetic studies indicated Curie–Weiss behavior above 100 K with significant anti-ferromagnetic coupling for both compounds, with further complex magnetic behavior at lower temperatures. The data indicate canted anti-ferromagnetic order below 57 K in Mn 5(VO 4) 2(OH) 4 and below 45 K in Mn 6O(VO 4) 2(OH). Members of another class of compounds, K 2M 3(VO 4) 2(OH) 2 (M = Mn, Co), also containing a honeycomb-type sublattice, were also synthesized to allow a comparison of the structural features across all three structure types and to demonstrate extension to other transition metals.« less

Multiscale Characterization of Microstructure in Near-Surface Regions of a 16MnCr5 Gear Wheel After Cyclic Loading

NASA Astrophysics Data System (ADS)

Medghalchi, Setareh; Jamebozorgi, Vahid; Bala Krishnan, Arjun; Vincent, Smobin; Salomon, Steffen; Basir Parsa, Alireza; Pfetzing, Janine; Kostka, Aleksander; Li, Yujiao; Eggeler, Gunther; Li, Tong

2018-05-01

The dependence of the microstructure on the degree of deformation in near-surface regions of a 16MnCr5 gear wheel after 2.1 × 106 loading cycles has been investigated by x-ray diffraction analysis, transmission electron microscopy, and atom probe tomography. Retained austenite and large martensite plates, along with elongated lamella-like cementite, were present in a less deformed region. Comparatively, the heavily deformed region consisted of a nanocrystalline structure with carbon segregation up to 2 at.% at grain boundaries. Spheroid-shaped cementite, formed at the grain boundaries and triple junctions of the nanosized grains, was enriched with Cr and Mn but depleted with Si. Such partitioning of Cr, Mn, and Si was not observed in the elongated cementite formed in the less deformed zone. This implies that rolling contact loading induced severe plastic deformation as well as a pronounced annealing effect in the active contact region of the toothed gear during cyclic loading.

Live-Cell MicroRNA Imaging through MnO2 Nanosheet-Mediated DD-A Hybridization Chain Reaction.

PubMed

Ou, Min; Huang, Jin; Yang, Xiaohai; He, Xiaoxiao; Quan, Ke; Yang, Yanjing; Xie, Nuli; Li, Jing; Wang, Kemin

2018-01-18

Innovative techniques to visualize native microRNAs (miRNAs) in live cells can dramatically impact current research on the roles of miRNA in biology and medicine. Here, we report a novel approach for live-cell miRNA imaging using a biodegradable MnO 2 nanosheet-mediated DD-A FRET hybridization chain reaction (HCR). The MnO 2 nanosheets can adsorb DNA hairpin probes and deliver them into live cells. After entering cells, the MnO 2 nanosheets are degraded by cellular GSH. Then, the target miR-21 triggers cascaded assembly of the liberated hairpin probes into long dsDNA polymers, which brings each two FAMs (donor) and one TAMRA (acceptor) into close proximity to generate significantly enhanced DD-A FRET signals, which was discovered and proven by our previous report. We think the developed approach can serve as an excellent intracellular miRNAs detection tool, which promises the potential for biological and disease studies. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Annealing effect on structural and optical properties of chemical bath deposited MnS thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ulutas, Cemal, E-mail: cemalulutas@hakkari.edu.tr; Gumus, Cebrail

2016-03-25

MnS thin film was prepared by the chemical bath deposition (CBD) method on commercial microscope glass substrate deposited at 30 °C. The as-deposited film was given thermal annealing treatment in air atmosphere at various temperatures (150, 300 and 450 °C) for 1 h. The MnS thin film was characterized by using X-ray diffraction (XRD), UV-vis spectrophotometer and Hall effect measurement system. The effect of annealing temperature on the structural, electrical and optical properties such as optical constants of refractive index (n) and energy band gap (E{sub g}) of the film was determined. XRD measurements reveal that the film is crystallized inmore » the wurtzite phase and changed to tetragonal Mn{sub 3}O{sub 4} phase after being annealed at 300 °C. The energy band gap of film decreased from 3.69 eV to 3.21 eV based on the annealing temperature.« less

Nano-level monitoring of Mn(2+) ion by fabrication of coated pyrolytic graphite electrode based on isonicotinohydrazide derivatives.

PubMed

Sahani, Manoj Kumar; Singh, A K; Jain, A K

2015-05-01

The two ionophores N'(N',N‴E,N',N‴E)-N',N‴-((((oxybis(ethane-2,1-diyl))bis(oxy)) bis(2,1-phenylene))bis(methanylylidene))di(isonicotinohydrazide) (I1) and (N',N‴E,N',N‴E)-N',N‴-(((propane-1,3-diylbis(oxy))bis(2,1-phenylene))bis(methanylylidene))di(isonicotinohydrazide) (I2) were synthesised and investigated as neutral carrier in the fabrication of Mn(2+) ion selective sensor. Several membranes were prepared by incorporating different plasticizers and anionic excluders and their effect on potentiometric response was studied. The best analytical performance was obtained with the electrode having a membrane of composition of I2: PVC: o-NPOE: NaTPB in the ratio of 6:34:58:2 (w/w, mg). Comparative studies of coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE) based on I2 reveal the superiority of CPGE. The CPGE exhibits wide working concentration range of 1.23×10(-8)-1.0×10(-1) mol L(-1) and a detection limit down to 4.78×10(-9) mol L(-1) with a Nernstian slope of 29.5±0.4 mV decade(-1) of activity. The sensor performs satisfactorily over a wide pH range (3.5-9.0) and exhibited a quick response time (9s). The sensor can work satisfactorily in water-acetonitrile and water-methanol mixtures. It can tolerate 30% acetonitrile and 20% methanol content in the mixtures. The sensor could be used for a period of four months without any significant divergence in performance. The sensor reflects its utility in the quantification of Mn(2+) ion in real samples and has been successfully employed as an indicator electrode in the potentiometric titration of Mn(2+) ion with ethylenediaminetetraacetic acid (EDTA). Copyright © 2015 Elsevier B.V. All rights reserved.

Enhanced magnetic hysteresis in Ni-Mn-Ga single crystal and its influence on magnetic shape memory effect

NASA Astrophysics Data System (ADS)

Heczko, O.; Drahokoupil, J.; Straka, L.

2015-05-01

Enhanced magnetic hysteresis due to boron doping in combination with magnetic shape memory effect in Ni-Mn-Ga single crystal results in new interesting functionality of magnetic shape memory (MSM) alloys such as mechanical demagnetization. In Ni50.0Mn28.5Ga21.5 single crystal, the boron doping increased magnetic coercivity from few Oe to 270 Oe while not affecting the transformation behavior and 10 M martensite structure. However, the magnetic field needed for MSM effect also increased in doped sample. The magnetic behavior is compared to undoped single crystal of similar composition. The evidence from the X-ray diffraction, magnetic domain structure, magnetization loops, and temperature evolution of the magnetic coercivity points out that the enhanced hysteresis is caused by stress-induced anisotropy.

Opportunities to improve the in vivo measurement of manganese in human hands.

PubMed

Aslam; Chettle, D R; Pejović-Milić, A; Waker, A J

2009-01-07

Manganese (Mn) is an element which is both essential for regulating neurological and skeletal functions in the human body and also toxic when humans are exposed to excessive levels. Its excessive inhalation as a result of exposure through industrial and environmental emissions can cause neurological damage, which may manifest as memory deficit, loss of motor control and reduction in the refinement of certain body motions. A number of clinical studies demonstrate that biological monitoring of Mn exposure using body fluids, particularly blood, plasma/serum and urine is of very limited use and reflect only the most recent exposure and rapidly return to within normal ranges. In this context, a non-invasive neutron activation technique has been developed at the McMaster University accelerator laboratory that could provide an alternative to measure manganese stored in the bones of exposed subjects. In a first pilot study we conducted recently on non-exposed human subjects to measure the ratio of Mn to Ca in hand bones, it was determined that the technique needed further development to improve the precision of the measurements. It could be achieved by improving the minimum detection limit (MDL) of the system from 2.1 microg Mn/g Ca to the reference value of 0.6 microg g(-1) Ca (range: 0.16-0.78 microg Mn/g Ca) for the non-exposed population. However, the developed procedure might still be 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. To improve the MDL of the technique to the expected levels of Mn in a reference population, the present study investigates further optimization of irradiation conditions, which includes the optimal selection of proton beam energy, beam current and irradiation time and the effect of upgrading the 4pi detection system. The maximum local dose equivalent that could be given to the hand as a result of irradiation was constrained to be less than 150 mSv as opposed to the previously imposed dose equivalent limit of 20 mSv. A maximum beam current, which could be delivered on the lithium target to produce neutrons, was restricted to 500 microA. The length of irradiation intervals larger than 10 min, was considered inconvenient and impractical to implement with Mn measurements in humans. To fulfil the requirements for developing a protocol for in vivo bone Mn measurements, a revised estimate of the dose equivalent has been presented here. Beam energy of 1.98 MeV was determined to be optimal to complete the irradiation procedure within 10 min using 500 microA beam current. The local dose equivalent given to hand was estimated as 118 mSv, which is lower by a factor of 1.5 compared to that of 2.00 MeV. The optimized beam parameters are expected to improve the currently obtained detection limit of 2.1 microg Mn/g Ca to 0.6 microg Mn/g Ca. Using this dose equivalent delivered to the central location of the hand, the average dose equivalent to the hand of 74 mSv and an effective dose of approximately 70 microSv will be accompanying the non-invasive, in vivo measurements of bone Mn, which is little over the chest radiograph examination dose.

Opportunities to improve the in vivo measurement of manganese in human hands

NASA Astrophysics Data System (ADS)

Aslam; Chettle, D. R.; Pejović-Milić, A.; Waker, A. J.

2009-01-01

Manganese (Mn) is an element which is both essential for regulating neurological and skeletal functions in the human body and also toxic when humans are exposed to excessive levels. Its excessive inhalation as a result of exposure through industrial and environmental emissions can cause neurological damage, which may manifest as memory deficit, loss of motor control and reduction in the refinement of certain body motions. A number of clinical studies demonstrate that biological monitoring of Mn exposure using body fluids, particularly blood, plasma/serum and urine is of very limited use and reflect only the most recent exposure and rapidly return to within normal ranges. In this context, a non-invasive neutron activation technique has been developed at the McMaster University accelerator laboratory that could provide an alternative to measure manganese stored in the bones of exposed subjects. In a first pilot study we conducted recently on non-exposed human subjects to measure the ratio of Mn to Ca in hand bones, it was determined that the technique needed further development to improve the precision of the measurements. It could be achieved by improving the minimum detection limit (MDL) of the system from 2.1 µg Mn/g Ca to the reference value of 0.6 µg g-1 Ca (range: 0.16-0.78 µg Mn/g Ca) for the non-exposed population. However, the developed procedure might still be 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. To improve the MDL of the technique to the expected levels of Mn in a reference population, the present study investigates further optimization of irradiation conditions, which includes the optimal selection of proton beam energy, beam current and irradiation time and the effect of upgrading the 4π detection system. The maximum local dose equivalent that could be given to the hand as a result of irradiation was constrained to be less than 150 mSv as opposed to the previously imposed dose equivalent limit of 20 mSv. A maximum beam current, which could be delivered on the lithium target to produce neutrons, was restricted to 500 µA. The length of irradiation intervals larger than 10 min, was considered inconvenient and impractical to implement with Mn measurements in humans. To fulfil the requirements for developing a protocol for in vivo bone Mn measurements, a revised estimate of the dose equivalent has been presented here. Beam energy of 1.98 MeV was determined to be optimal to complete the irradiation procedure within 10 min using 500 µA beam current. The local dose equivalent given to hand was estimated as 118 mSv, which is lower by a factor of 1.5 compared to that of 2.00 MeV. The optimized beam parameters are expected to improve the currently obtained detection limit of 2.1 µg Mn/g Ca to 0.6 µg Mn/g Ca. Using this dose equivalent delivered to the central location of the hand, the average dose equivalent to the hand of 74 mSv and an effective dose of approximately 70 µSv will be accompanying the non-invasive, in vivo measurements of bone Mn, which is little over the chest radiograph examination dose.

Nanoscale Mechanical Properties of Nanoindented Ni48.8Mn27.2Ga24 Ferromagnetic Shape Memory Thin Film

PubMed Central

Fu, Xiaofei; Li, Xianli; Lv, Jingwei; Wang, Famei; Wang, Liying

2017-01-01

The structure and nanoscale mechanical properties of Ni48.8Mn27.2Ga24 thin film fabricated by DC magnetron sputtering are investigated systematically. The thin film has the austenite state at room temperature with the L21 Hesuler structure. During nanoindentation, stress-induced martensitic transformation occurs on the nanoscale for the film annealed at 823 K for 1 hour and the shape recovery ratio is up to 85.3%. The associated mechanism is discussed. PMID:29109812

Slow magnetic relaxation in a dimeric Mn2Ca2 complex enabled by the large Mn(iii) rhombicity.

PubMed

Arauzo, Ana; Bartolomé, Elena; Benniston, Andrew C; Melnic, Silvia; Shova, Sergiu; Luzón, Javier; Alonso, Pablo J; Barra, Anne-Laure; Bartolomé, Juan

2017-01-17

In this paper we present the characterization of a complex with the formula [Mn 2 Ca 2 (hmp) 6 (H 2 O) 4 (CH 3 CN) 2 ](ClO 4 ) 4 (1), where hmp-H = 2-(hydroxymethyl)pyridine. Compound 1 crystallizes in the monoclinic space group C2/c with the cation lying on an inversion centre. Static magnetic susceptibility, magnetization and heat capacity measurements reflect a unique Mn(iii) valence state, and single-ion ligand field parameters with remarkable large rhombic distortion (D/k B = -6.4 K, E/k B = -2.1 K), in good agreement with the high-field electron paramagnetic resonance experiments. At low temperature Mn 2 Ca 2 cluster behaves as a system of ferromagnetically coupled (J/k B = 1.1 K) Mn dimers with a S T = 4 and m T = ±4 ground state doublet. Frequency dependent ac susceptibility measurements reveal the slow magnetic relaxation characteristic of a single molecule magnet (SMM) below T = 4 K. At zero magnetic field, an Orbach-type spin relaxation process (τ ∼ 10 -5 s) with an activation energy E a = 5.6 K is observed, enabled by the large E/D rhombicity of the Mn(iii) ions. Upon the application of a magnetic field, a second, very slow process (τ ∼ 0.2 s) is observed, attributed to a direct relaxation mechanism with enhanced relaxation time owing to the phonon bottleneck effect.

Dramatic influence of an anionic donor on the oxygen-atom transfer reactivity of a Mn(V) -oxo complex.

PubMed

Neu, Heather M; Quesne, Matthew G; Yang, Tzuhsiung; Prokop-Prigge, Katharine A; Lancaster, Kyle M; Donohoe, James; DeBeer, Serena; de Visser, Sam P; Goldberg, David P

2014-11-03

Addition of an anionic donor to an Mn(V) (O) porphyrinoid complex causes a dramatic increase in 2-electron oxygen-atom-transfer (OAT) chemistry. The 6-coordinate [Mn(V) (O)(TBP8 Cz)(CN)](-) was generated from addition of Bu4 N(+) CN(-) to the 5-coordinate Mn(V) (O) precursor. The cyanide-ligated complex was characterized for the first time by Mn K-edge X-ray absorption spectroscopy (XAS) and gives MnO=1.53 Å, MnCN=2.21 Å. In combination with computational studies these distances were shown to correlate with a singlet ground state. Reaction of the CN(-) complex with thioethers results in OAT to give the corresponding sulfoxide and a 2e(-) -reduced Mn(III) (CN)(-) complex. Kinetic measurements reveal a dramatic rate enhancement for OAT of approximately 24 000-fold versus the same reaction for the parent 5-coordinate complex. An Eyring analysis gives ΔH(≠) =14 kcal mol(-1) , ΔS(≠) =-10 cal mol(-1)  K(-1) . Computational studies fully support the structures, spin states, and relative reactivity of the 5- and 6-coordinate Mn(V) (O) complexes. © 2014 The Authors. Published by Wiley-VCHVerlag GmbH & Co. KGaA. This is an open access article under the terms ofthe Creative Commons Attribution License, which permits use, distribution andreproduction in any medium, provided the original work is properly cited.

Scaling of the stochastic broadening from low mn, high mn, and peeling-ballooning magnetic perturbations in the DIII-D tokamak

NASA Astrophysics Data System (ADS)

Zhao, Michael; Punjabi, Alkesh; Ali, Halima

2009-11-01

The equilibrium EFIT data for the DIII-D shot 115467 is used to construct the equilibrium generating function for magnetic field line trajectories in the DIII-D tokamak in natural canonical coordinates [A. Punjabi, and H. Ali, Phys. Plasmas 15, 122502 (2008)]. A canonical transformation is used to construct an area-preserving map for field line trajectories in the natural canonical coordinates in the DIII-D. Maps in natural canonical coordinates have the advantage that natural canonical coordinates can be inverted to calculate real space coordinates (R,Z,φ), and there is no problem in crossing the separatrix. This is not possible for magnetic coordinates [O. Kerwin, A. Punjabi, and H. Ali, Phys. Plasmas 15, 072504 (2008)]. This map is applied to calculate stochastic broadening from the low mn (m,n)=(1,1)+(1,-1); high mn (m,n)=(4,1)+(3,1); and the peeling-ballooning (m,n)=(40,10)+(30,10) magnetic perturbations. In all three cases, the scaling of the widths of stochastic layer near the X-point in the principal plane of the DIII-D deviates at most by 6% from the .5ex1 -.1em/ -.15em.25ex2 power Boozer-Rechester scaling [A. Boozer, and A. Rechester, Phys. Fluids 21, 682 (1978)]. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.

Pathways of Pb and Mn observed in a 5-year longitudinal investigation in young children and environmental measures from an urban setting.

PubMed

Gulson, Brian; Mizon, Karen; Taylor, Alan; Korsch, Michael; Davis, J Michael; Louie, Honway; Wu, Michael; Gomez, Laura; Antin, Luminita

2014-08-01

We monitored 108 children ≤5 years on a 6-month basis for up to 5 years in a major urban setting. Samples (n ∼ 7000) included blood, urine, handwipes (interior, and after exterior playing), 6-day duplicate diet, drinking water, interior house and day care dust-fall accumulation using petri dishes, exterior dust-fall accumulation, exterior dust sweepings, paint, soil and urban air. The geometric mean blood Pb (PbB) was 2.1 μg/dL and blood Mn (MnB) was 10.0 μg/L. Following a path modelling approach, mixed model analyses for a fully adjusted model showed the strongest associations for PbB were with interior house dust and soil; for MnB there were no significant associations with any predictors. Predictor variables only explained 9% of the variance for Pb and 0.7% for Mn. Relationships between environmental measures and PbB in children are not straightforward; soil and dust sweepings contribute only about 1/5th of the amounts to PbB found in other studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mn(II) based T1 and T2 potential MRI contrast agent appended with tryptamine: Recognition moiety for Aβ-plaques.

PubMed

Rastogi, Neeraj; Tyagi, Nidhi; Singh, Ovender; Hemanth Kumar, B S; Singh, Udai P; Ghosh, Kaushik; Roy, Raja

2017-12-01

We report the synthesis and characterization of manganese(II) complexes having pentadentate ligands L 1 (2,6-bis(1-(2-phenyl-2-(pyridin-2-yl)hydrazono)ethyl)pyridine), L 2 (methyl 2,6-bis((E)-1-(2-phenyl-2-(pyridin-2yl)hydrazono)ethyl)isonicotinate), L 3 (N-(2-(1H-indol-3-yl)ethyl)-2,6-bis((E)-1-(2-phenyl-2-(pyridin2yl)hydrazono)ethyl)isonicotiamide) and their application as dual contrast agents for simultaneous T 1 and T 2 weighted magnetic resonance imaging. Single crystal analysis of all the complexes [Mn II L 1 , Mn II L 2 and Mn II L 3 ] confirm the formation of novel seven-coordinate manganese complexes with an inner sphere water and perchlorate ion. The Magnetic Resonance Imaging (MRI) contrast agent [MnL 2 ] was further modified by incorporating tryptamine as a binding moiety specific to Amyloid Beta-fibrils (Aβ-fibrils) in Alzhiemer's disease (AD) and it's in vitro evaluation for specific binding with Aβ-fibrils indicated as a bio-marker of AD. Copyright © 2017 Elsevier Inc. All rights reserved.

Asymmetric supercapacitors based on electrospun carbon nanofiber/sodium-pre-intercalated manganese oxide electrodes with high power and energy densities

NASA Astrophysics Data System (ADS)

Lin, Sheng-Chi; Lu, Yi-Ting; Chien, Yu-An; Wang, Jeng-An; Chen, Po-Yu; Ma, Chen-Chi M.; Hu, Chi-Chang

2018-07-01

The sodium-pre-intercalated δ-MnO2 is in-situ grown on carbon nanofiber via a simple, one-step method for the application of asymmetric supercapacitors. The pre-intercalation of Na ions into the layered structure of δ-MnO2 reduces the crystallinity, beneficial to Na+ diffusion into/out the interlayer structure and pseudocapacitive utilization of MnO2. This NaxMnO2@CNF nanocomposite with desirable pseudo-capacitance from δ-NaxMnO2 and high electric conductivity from CNF network shows a high specific capacitance of 321 F g-1 at 1 A g-1 with ca. 75.2% capacitance retention from 1 to 32 A g-1. An ASC cell consisting of this nanocomposite and activated carbon as the positive and negative electrodes can be reversibly charged and discharged to a cell voltage of 2.0 V in 1 M Na2SO4 and 4 mM NaHCO3 with specific energy and power of 21 Wh kg-1 and 1 kW kg-1, respectively. This ASC also shows excellent cell capacitance retention (7% decay) in the 2 V, 10,000-cycle stability test, revealing superior performance.

Microstructure and Mechanical Properties of a Low Alloyed MnB Cast Steel

NASA Astrophysics Data System (ADS)

Luo, Kaishuang; Bai, Bingzhe

2010-08-01

The microstructure and mechanical properties of a low alloyed MnB cast steel designed for coupler castings of trucks were studied. The results show that the microstructure of the MnB cast steel after water quenching is lath martensite and a small amount of massive islands in the matrix of lath martensite. The average size of the martensite packets is about 10 μm in length. Carbides precipitated dispersively at the tempering temperature of 450 °C. The carbides are slender and fibrous, of which the microstructure was θ-phase (Fe, Mn)3C characterized by TEM. The MnB cast steel has good hardenability and tempering stability. Excellent combination of strength, ductility and low-temperature toughness were obtained after water-quenching and 450 °C tempering: Rm = 960-1040 MPa, ReL = 880-900 MPa, A = 19-21%, Z = 56-58%. Especially, the impact energy of the Charpy V-Notch (CVN) specimens reached 70-88 J at -40 °C. The fracture mechanism is transcrystalline fracture both for ambient temperature uniaxial tensile test specimens and for CVN impact test specimens broken at -40 °C, where the whole surfaces were manifested as voids and dimples.

Two-dimensional La2/3Sr4/3MnO4 Manganite Films Probed by Epitaxial Strain and Cation Ordering

NASA Astrophysics Data System (ADS)

Nelson-Cheeseman, Brittany; Santos, Tiffany; Bhattacharya, Anand

2010-03-01

Dimensionality is known to play a central role in the properties of strongly correlated systems. Here we investigate magnetism and transport in thin films of the Ruddlesden-Popper n=1 phase, La1-xSr1+xMnO4. Within this material, the MnO6-octahedra form two-dimensional perovskite sheets separated by an extra rocksalt layer. By fabricating high quality thin films with ozone-assisted molecular beam epitaxy, we study how the effects of epitaxial strain and intentional cation ordering, known as digital synthesis, influence the properties of this 2-dimensional manganite. For example, at the same Mn^3+:Mn^4+ ratio (2:1) as its fully spin-polarized 3D manganite counterpart, this two dimensional analog at x=1/3 only displays a spin glass phase below 20K in bulk. This is believed to result from a competition between superexchange and double exchange, as well as disordered Jahn-Teller distortions. However, in our films we find weak ferromagnetic order up to much higher temperatures in addition to a low temperature spin glass phase. We will discuss how strain and cation order effect the presence of this weak ferromagnetism.

Culturable Rhodobacter and Shewanella species are abundant in estuarine turbidity maxima of the Columbia River

PubMed Central

Bräuer, S. L.; Adams, C.; Kranzler, K.; Murphy, D.; Xu, M.; Zuber, P.; Simon, H. M.; Baptista, A. M.; Tebo, B. M.

2017-01-01

Summary Measurements of dissolved, ascorbate-reducible and total Mn by ICP-OES revealed significantly higher concentrations during estuarine turbidity maxima (ETM) events, compared with non-events in the Columbia River. Most probable number (MPN) counts of Mn-oxidizing or Mn-reducing heterotrophs were not statistically different from that of other heterotrophs (103–104 cells ml−1) when grown in defined media, but counts of Mn oxidizers were significantly lower in nutrient-rich medium (13 cells ml−1). MPN counts of Mn oxidizers were also significantly lower on Mn(III)-pyrophosphate and glycerol (21 cells ml−1). Large numbers of Rhodobacter spp. were cultured from dilutions of 10−2 to 10−5, and many of these were capable of Mn(III) oxidation. Up to c. 30% of the colonies tested LBB positive, and all 77 of the successfully sequenced LBB positive colonies (of varying morphology) yielded sequences related to Rhodobacter spp. qPCR indicated that a cluster of Rhodobacter isolates and closely related strains (95–99% identity) represented approximately 1–3% of the total Bacteria, consistent with clone library results. Copy numbers of SSU rRNA genes for either Rhodobacter spp. or Bacteria were four to eightfold greater during ETM events compared with non-events. Strains of a Shewanella sp. were retrieved from the highest dilutions (10−5) of Mn reducers, and were also capable of Mn oxidation. The SSU rRNA gene sequences from these strains shared a high identity score (98%) with sequences obtained in clone libraries. Our results support previous findings that ETMs are zones with high microbial activity. Results indicated that Shewanella and Rhodobacter species were present in environmentally relevant concentrations, and further demonstrated that a large proportion of culturable bacteria, including Shewanella and Rhodobacter spp., were capable of Mn cycling in vitro. PMID:20977571

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

To assist developments of the continuous-casting technology of Fe-Mn-Al-C steels, the solidification structures and the thermal properties of Fe-Mn-Al-C steel ingots with different manganese contents have been investigated and the phase transformation characteristics have been revealed by FactSage (CRCT-ThermFact Inc., Montréal, Canada). The results show that the thermal conductivity of the 0Mn steel is the highest, whereas the thermal conductivity of the 8Mn steel is slightly higher than that of the 17Mn steel. Increasing the manganese content promotes a columnar solidification structure and coarse grains in steel. With the increase of manganese content, the mass fraction of austenite phase is increased. Finally, a single austenite phase is formed in the 17Mn steel. The mean thermal expansion coefficients of the steels are in the range from 1.3 × 10-5 to 2.3 × 10-5 K-1, and these values increase with the increase of manganese content. The ductility of the 17Mn steel and the 8Mn steel are higher than 40 pct in the temperature range from 873 K to 1473 K (600 °C to 1200 °C), and the cracking during the straightening operation should be avoided. However, the ductility of the 0Mn steel is lower than 40 pct at 973 K and 1123 K (700 °C and 850 °C), which indicates that the temperature of the straightening operation during the continuous-casting process should be above 1173 K (900 °C). Manganese has the effect of enlarging the austenite phase region and reducing the δ-ferrite phase region and α-ferrite phase region. At the 2.1 mass pct aluminum level, the precipitate temperature of AlN is high. Thus, the formed AlN is too coarse to deteriorate the hot ductility of steel.

Evaluation of the sensitivity and specificity of in vivo erythrocyte micronucleus and transgenic rodent gene mutation tests to detect rodent carcinogens.

PubMed

Morita, Takeshi; Hamada, Shuichi; Masumura, Kenichi; Wakata, Akihiro; Maniwa, Jiro; Takasawa, Hironao; Yasunaga, Katsuaki; Hashizume, Tsuneo; Honma, Masamitsu

2016-05-01

Sensitivity and/or specificity of the in vivo erythrocyte micronucleus (MN) and transgenic rodent mutation (TGR) tests to detect rodent carcinogens and non-carcinogens were investigated. The Carcinogenicity and Genotoxicity eXperience (CGX) dataset created by Kirkland et al. was used for the carcinogenicity and in vitro genotoxicity data, i.e., Ames and chromosome aberration (CA) tests. Broad literature surveys were conducted to gather in vivo MN or TGR test data to add to the CGX dataset. Genotoxicity data in vitro were also updated slightly. Data on 379 chemicals (293 carcinogens and 86 non-carcinogens) were available for the in vivo MN test; sensitivity, specificity or concordances were calculated as 41.0%, 60.5% or 45.4%, respectively. For the TGR test, data on 80 chemicals (76 carcinogens and 4 non-carcinogens) were available; sensitivity was calculated as 72.4%. Based on the recent guidance on genotoxicity testing strategies, performance (sensitivity/specificity) of the following combinations was calculated; Ames+in vivo MN (68.7%/45.3%), Ames+TGR (83.8%/not calculated (nc)), Ames+in vitro CA+in vivo MN (80.8%/21.3%), Ames+in vitro CA+TGR (89.1%/nc), Ames+in vivo MN+TGR (87.5%/nc), Ames+in vitro CA+in vivo MN+TGR (89.3%/nc). Relatively good balance in performance was shown by the Ames+in vivo MN in comparison with Ames+in vitro CA (74.3%/37.5%). Ames+TGR and Ames+in vivo MN+TGR gave even higher sensitivity, but the specificity could not be calculated (too few TGR data on non-carcinogens). This indicates that in vivo MN and TGR tests are both useful as in vivo tests to detect rodent carcinogens. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Reproductive performance of postpartum ewes treated with insulin or progesterone hormones in association with ram effect.

PubMed

Ferreira-Silva, J C; Basto, Srl; Tenório Filho, F; Moura, M T; Silva Filho, M L; Oliveira, Mal

2017-08-01

The reproductive performance of postpartum Santa Inês (SI) and Morada Nova (MN) ewes treated with insulin or progesterone hormones in association with ram effect was evaluated. Ewes from SI (n = 69) and MN (n = 69) breeds were randomly allocated to three groups of each breed (T1-ram effect only; T2-ram effect + insulin; T3-ram effect + progesterone). Progesterone concentrations (ηg/ml; mean ± SD) before and after introduction of rams (n = 6) were 0.51 ± 0.22 and 3.78 ± 0.68 (T1), 0.65 ± 0.21 and 3.77 ± 0.78 (T2) and 0.52 ± 0.21 and 3.84 ± 0.84 (T3) in SI ewes and 0.74 ± 0.19 and 3.71 ± 0.56 (T1), 0.70 ± 0.21 and 3.79 ± 0.75 (T2) and 0.81 ± 0.14 and 3.87 ± 0.80 (T3) in MN ewes, respectively. Thus, lower progesterone concentrations were found before the introduction of rams (p < .05). After the introduction of rams, preovulatory peaks of LH (ηg/ml) occurred at 28 (T1), 44 (T2) and 48 (T3) hr in SI ewes and at 64 (T1), 40 (T2) and 44 (T3) hr in MN ewes. The mean number of ovulations was similar between groups (p > .05), was 1.3 ± 0.51 (T1), 1.5 ± 0.54 (T2) and 1.6 ± 0.51 (T3) in SI ewes and 1.3 ± 0.51 (T1), 1.6 ± 0.51 (T2) and 1.6 ± 0.51 (T3) in MN ewes. In conclusion, the ram effect alone is effective at inducing and synchronizing oestrus in sheep under postpartum anoestrus, irrespective of hormone treatments. © 2017 Blackwell Verlag GmbH.

Tetragonal-antiprismatic coordination of transition metals in intermetallic compounds: ω1-Mn6Ga29 and its structuralrelationships

NASA Astrophysics Data System (ADS)

Antonyshyn, Iryna; Prots, Yurii; Margiolaki, Irene; Schmidt, Marcus Peter; Zhak, Olga; Oryshchyn, Stepan; Grin, Yuri

2013-03-01

The new phase ω1-Mn6Ga29 was synthesised in single-crystal form from the elements applying the high-temperature centrifugation-aided filtration technique. The crystal structure was determined using diffraction data collected from a twinned specimen: a new prototype, space group P1¯; a=6.3114(2) Å, b=9.9557(3) Å, c=18.920(1) Å, α=90.473(1)°, β=90.847(1)°, γ=90.396(1)°; R1=0.047, wR2=0.117 for 317 variable parameters and 7346 observed reflections; twinning matrix 0 0 -1/3, 0 -1 0, -3 0 0; twin domains ratio 0.830(3):0.170. All manganese atoms in the crystal structure of ω1-Mn6Ga29 are coordinated exclusively by Ga forming distorted tetragonal antiprisms. The monocapped [MnGa8+1] antiprisms condense into pairs by sharing their pseudo-quadratic faces and are interconnected via common apexes and edges to form a 3D framework. The relationship between the crystal structures of ω1-Mn6Ga29 and CuAl2, α-, β-CoSn3, PtSn4, Ti4MnBi2, PdGa5, Rh3Ga16, Rh4Ga21, Al7FeCu2, Co2Al9, and RhBi4 is discussed.

Effect of metal ratio and calcination temperature of chromium based mixed oxides catalyst on FAME density from palm fatty acid distillate

NASA Astrophysics Data System (ADS)

Wan, Z.; Fatimah, S.; Shahar, S.; Noor, A. C.

2017-09-01

Mixed oxides chromium based catalysts were synthesized via sol-gel method for the esterification of palm fatty acid distillate (PFAD) to produce fatty acid methyl ester (FAME). The reactions were conducted in a batch reactor at reaction temperature of 160 °C for 4 h and methanol to PFAD molar ratio of 3:1. The effects of catalyst preparation conditions which are the mixed metal ratio and calcination temperature were studied. The various metal ratio of Cr:Mn (1:0, 0:1, 1:1, 1:2 and 2:1) and Cr:Ti (0:1, 1:1, 1:2 and 2:1) resulted in FAME density ranges from 1.041 g/cm3 to 0.853 g/cm3 and 1.107 g/cm3 to 0.836 g/cm3, respectively. The best condition catalyst was found to be Cr:Ti metal ratio of 1:2 and Cr:Mn metal ratio of 1:1. The calcination temperature of the mixed oxides between 300 °C to 700°C shows effect on the FAME density obtained in the reaction. The calcination at 500°C gave the lowest FAME density of 0.836 g/cm3 and 0.853 g/cm3 for Cr:Ti and Cr:Mn mixed oxides, respectively. The density of FAME is within the value range of the biodiesel fuel property. Thus, mixed oxides of Cr-Ti and Cr-Mn have good potentials as heterogeneous catalyst for FAME synthesis from high acid value oils such as PFAD.

Marine molluscs as biomonitors for heavy metal levels in the Gulf of Suez, Red Sea

NASA Astrophysics Data System (ADS)

Hamed, Mohamed A.; Emara, Ahmed M.

2006-05-01

Levels of the heavy metals Copper (Cu), Zinc (Zn), Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni), Iron (Fe) and Manganese (Mn) were determined in coastal water, sediments and soft tissues of the gastropod limpet, Patella caerulea, and the bivalve, Barbatus barbatus, from seven different stations in the western coast of the Gulf of Suez. The concentrations of heavy metals in water ranged between 3.37-4.78, 18.83-21.46, 2.75-3.17, 0.22-0.27, 0.99-1.21, 2.69-3.65, 3.75-4.56 μg L - 1 and 23.82-32.78 mg g - 1 for Cu, Zn, Pb, Cd, Cr, Ni, Mn and Fe, respectively. The corresponding concentration values in the sediments were 8.65-12.16, 51.78-58.06, 36.52-42.15, 3.23-3.98, 9.03-12.75, 34.31-49.63, 3.28-4.56 and 64.20-70.22 μg g - 1 for Cu, Zn, Pb, Cd, Cr, Ni, Mn and Fe, respectively. The highest accumulated metals were Fe, Zn and Mn in both P. caerulea and B. barbatus, while the lowest one was Cd. The accumulation of metals was more pronounced in P. caerulea than B. barbatus. The highest concentrations of all metals in water, sediments and mollusca were recorded at Adabiya harbour north of the Gulf, while the lowest concentrations were recorded at Gabal El-Zeit and Hurghada. Land based activities and ships awaiting berth are the main source of metal pollution in the northern part of the Gulf.

Magnetostratigraphy of the Vallesian (late Miocene) in the Vallès-Penedès Basin (northeast Spain)

NASA Astrophysics Data System (ADS)

Garcés, M.; Agustí, J.; Cabrera, L.; Parés, J. M.

1996-08-01

The magnetostratigraphic analysis of the late Miocene continental deposits from the Vallès-Penedès Basin, combined with its well-documented fossil mammal record, has provided a well-resolved chronology for the upper basin infill. The study is based on the biostratigraphic and magnetostratigraphic cross-correlation of 12 sections throughout the alluvial sequences in the western Vallès area. The biostratigraphic framework consists of 21 mammal localities corresponding to the Mammal Neogene MN9 and MN10 units. The composite magnetic polarity sequence is based on 400 paleomagnetic sites. Correlation with the Geomagnetic Polarity Time Scale (GPTS) has led to an absolute dating of the faunal events and a precise chronostratigraphy of the Vallesian mammal stage in its type area. The Hipparion First Appearance Datum (FAD), at the MN8/MN9 boundary, is dated at 11.1 Ma in the Vallès-Penedès Basin. This age, compared to other radiometrically dated localities in Europe, North Africa and Turkey, is consistent with an isochronous dispersal of this equid through the Mediterranean region. A possible isochrony at a larger geographical scale (Old World, Mesogea) must await more reliable ages of the Hipparion FAD in Asia and Africa. The Cricetulodon FAD ( MN9a/MN9b boundary) is dated to 10.4 Ma, in chron C5n. The Progonomys FAD ( MN9/MN10 boundary), corresponding to the intra-Vallesian faunal crisis, is dated at 9.7 Ma (C4Ar.3r). The Vallesian spans 2.4 Myr, from 11.1 Ma (C5r.1n) to 8.7 Ma (C4An) and correlates to the early Tortonian.

Neurobehavioral function in school-age children exposed to manganese in drinking water.

PubMed

Oulhote, Youssef; Mergler, Donna; Barbeau, Benoit; Bellinger, David C; Bouffard, Thérèse; Brodeur, Marie-Ève; Saint-Amour, Dave; Legrand, Melissa; Sauvé, Sébastien; Bouchard, Maryse F

2014-12-01

Manganese neurotoxicity is well documented in individuals occupationally exposed to airborne particulates, but few data are available on risks from drinking-water exposure. We examined associations of exposure from concentrations of manganese in water and hair with memory, attention, motor function, and parent- and teacher-reported hyperactive behaviors. We recruited 375 children and measured manganese in home tap water (MnW) and hair (MnH). We estimated manganese intake from water ingestion. Using structural equation modeling, we estimated associations between neurobehavioral functions and MnH, MnW, and manganese intake from water. We evaluated exposure-response relationships using generalized additive models. After adjusting for potential confounders, a 1-SD increase in log10 MnH was associated with a significant difference of -24% (95% CI: -36, -12%) SD in memory and -25% (95% CI: -41, -9%) SD in attention. The relations between log10 MnH and poorer memory and attention were linear. A 1-SD increase in log10 MnW was associated with a significant difference of -14% (95% CI: -24, -4%) SD in memory, and this relation was nonlinear, with a steeper decline in performance at MnW > 100 μg/L. A 1-SD increase in log10 manganese intake from water was associated with a significant difference of -11% (95% CI: -21, -0.4%) SD in motor function. The relation between log10 manganese intake and poorer motor function was linear. There was no significant association between manganese exposure and hyperactivity. Exposure to manganese in water was associated with poorer neurobehavioral performances in children, even at low levels commonly encountered in North America.

Magnetic versus manual catheter navigation for ablation of free wall accessory pathways in children.

PubMed

Kim, Jeffrey J; Macicek, Scott L; Decker, Jamie A; Kertesz, Naomi J; Friedman, Richard A; Cannon, Bryan C

2012-08-01

Transcatheter ablation of accessory pathway (AP)-mediated tachycardia is routinely performed in children. Little data exist regarding the use of magnetic navigation (MN) and its potential benefits for ablation of AP-mediated tachycardia in this population. We performed a retrospective review of prospectively gathered data in children undergoing radiofrequency ablation at our institution since the installation of MN (Stereotaxis Inc, St. Louis, MO) in March 2009. The efficacy and safety between an MN-guided approach and standard manual techniques for mapping and ablation of AP-mediated tachycardia were compared. During the 26-month study period, 145 patients underwent radiofrequency ablation for AP-mediated tachycardia. Seventy-three patients were ablated with MN and 72 with a standard manual approach. There were no significant differences in demographic factors between the 2 groups with a mean cohort age of 13.1±4.0 years. Acute success rates were equivalent with 68 of 73 (93.2%) patients in the MN group being successfully ablated versus 68 of 72 (94.4%) patients in the manual group (P=0.889). During a median follow-up of 21.4 months, there were no recurrences in the MN group and 2 recurrences in the manual group (P=0.388). There were no differences in time to effect, number of lesions delivered, or average ablation power. There was also no difference in total procedure time, but fluoroscopy time was significantly reduced in the MN group at 14.0 (interquartile range, 3.8-23.9) minutes compared with the manual group at 28.1 (interquartile range, 15.3-47.3) minutes (P<0.001). There were no complications in either group. MN is a safe and effective approach to ablate AP-mediated tachycardia in children.

Color-tunable photoluminescence and energy transfer properties of single-phase Ba{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+}, Mn{sup 2+} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Qingfeng; Liao, Libing, E-mail: clayl@cugb.edu.cn; Mei, Lefu, E-mail: mlf@cugb.edu.cn

2015-12-15

Single-phase Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} samples with apatite structure have been synthesized via a solid-state reaction method. The phase structure, luminescence properties, lifetime, PL thermal stability, as well as fluorescence decay curves of the samples were investigated. Effective energy transfer occurs from Eu{sup 2+} to Mn{sup 2+} in Ba{sub 10}(PO{sub 4}){sub 6}O and a possible mechanism of the energy-transfer from Eu{sup 2+} to Mn{sup 2+} is proposed. The critical distances R{sub c} was calculated by concentration quenching and turned out to be about 0.817 nm (x{sub c}=0.21). The CIE and thermally stable luminescence behaviors of Ba{sub 9.94}(PO{sub 4}){submore » 6}O:0.06Eu{sup 2+} phosphor were also studied in detail. All the results indicate that Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+}, yMn{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white light-emitting diodes. - Graphical abstract: Crystal structure and luminescence property of Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} have been discussed. - Highlights: • Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} was firstly reported. • Ba{sub 9.94}(PO{sub 4}){sub 6}O:0.06Eu{sup 2+} exhibits high thermal quenching resistance. • The energy transfer between Eu{sup 2+} and Mn{sup 2+} was investigated.« less

Improved thermal stability of Mn-Ir-based magnetic tunnel junction with nano-oxide layer

NASA Astrophysics Data System (ADS)

Yoon, S. Y.; Kim, Y. I.; Lee, D. H.; Kim, Y. S.; Suh, S. J.

2004-06-01

Si/SiO2/Ta/NiFe/Mn-Ir/CoFe/NOL/CoFe/Al-O/CoFe/NiFe/Ta bottom conventional (without nano-oxide layer, NOL) and specular (with NOL) MTJs were prepared by DC magnetron sputtering methods. In the case of a conventional MTJ, the TMR ratio increased up to 300 °C but the TMR ratio of a specular MTJ increased up to 400 °C. The highest TMR ratios of two samples after annealing at each optimal temperature were 21.6% (conventional MTJ) and 22.7% (specular MTJ), respectively, This improved thermal property of the specular MTJ is due to the NOL, which could act as a diffusion barrier for Mn. The bias-voltage dependence of both samples was vastly improved after annealing at each optimal temperature.

Magneto-optical spectroscopy of ferromagnetic shape-memory Ni-Mn-Ga alloy

NASA Astrophysics Data System (ADS)

Veis, M.; Beran, L.; Zahradnik, M.; Antos, R.; Straka, L.; Kopecek, J.; Fekete, L.; Heczko, O.

2014-05-01

Magneto-optical properties of single crystal of Ni50.1Mn28.4Ga21.5 magnetic shape memory alloy in martensite and austenite phase were systematically studied. Crystal orientation was approximately along {100} planes of parent cubic austenite. At room temperature, the sample was in modulated 10M martensite phase and transformed to cubic austenite at 323 K. Spectral dependence of polar magneto-optical Kerr effect was obtained by generalized magneto-optical ellipsometry with rotating analyzer in the photon energy range from 1.2 to 4 eV, and from room temperature to temperature above the Curie point. The Kerr rotation spectra exhibit prominent features typical for complexes containing Mn atoms. Significant spectral changes during transformation to austenite can be explained by different optical properties caused by changes in density of states near the Fermi energy.

Decontamination of coal mine effluent generated at the Rajrappa coal mine using phytoremediation technology.

PubMed

Lakra, Kalpana C; Lal, B; Banerjee, T K

2017-06-03

Toxicity of the effluent generated at the Rajrappa coal mine complex under the Central Coalfields Limited (CCL, a subsidiary of Coal India Limited) in Jharkhand, India was investigated. The concentrations (mg L -1 ) of all the toxic metals (Fe, Mn, Ni, Zn, Cu, Pb, Cr, and Cd) in the coal mine effluent were above the safe limit suggested by the Environmental Protection Agency (EPA 2003). Among these, Fe showed the highest concentration (18.21 ± 3.865), while Cr had the lowest effluent concentration (0.15 ± 0.014). Efforts were also made to detoxify the effluent using two species of aquatic macrophytes namely "'Salvinia molesta and Pistia stratiotes." After 10 days of phytoremediation, S. molesta removed Pb (96.96%) > Ni (97.01%) > Cu (96.77%) > Zn (96.38%) > Mn (96.22%) > Fe (94.12%) > Cr (92.85%) > Cd (80.99%), and P. stratiotes removed Pb (96.21%) > Fe (94.34%) > Ni (92.53%) > Mn (85.24%) > Zn (79.51%) > Cr (78.57%) > Cu (74.19%) > Cd (72.72%). The impact of coal mine exposure on chlorophyll content showed a significant decrease of 42.49% and 24.54% from control values in S. molesta and P. stratiotes, respectively, perhaps due to the damage inflicted by the toxic metals, leading to the decay of plant tissues.

Ultrahigh-resolution crystal structures of Z-DNA in complex with Mn(2+) and Zn(2+) ions.

PubMed

Drozdzal, Pawel; Gilski, Miroslaw; Kierzek, Ryszard; Lomozik, Lechoslaw; Jaskolski, Mariusz

2013-06-01

X-ray crystal structures of the spermine(4+) form of the Z-DNA duplex with the self-complementary d(CG)3 sequence in complexes with Mn(2+) and Zn(2+) cations have been determined at the ultrahigh resolutions of 0.75 and 0.85 Å, respectively. Stereochemical restraints were only used for the sperminium cation (in both structures) and for nucleotides with dual conformation in the Zn(2+) complex. The Mn(2+) and Zn(2+) cations at the major site, designated M(2+)(1), bind at the N7 position of G6 by direct coordination. The coordination geometry of this site was octahedral, with complete hydration shells. An additional Zn(2+)(2) cation was bis-coordinated in a tetrahedral fashion by the N7 atoms of G10 and G12 from a symmetry-related molecule. The coordination distances of Zn(2+)(1) and Zn(2+)(2) to the O6 atom of the guanine residues were 3.613 (6) and 3.258 (5) Å, respectively. Moreover, a chloride ion was also identified in the coordination sphere of Zn(2+)(2). Alternate conformations were observed in the Z-DNA-Zn(2+) structure not only at internucleotide linkages but also at the terminal C3'-OH group of G12. The conformation of the sperminium chain in the Z-DNA-Mn(2+) complex is similar to the spermine(4+) conformation in analogous Z-DNA-Mg(2+) structures. In the Z-DNA-Zn(2+) complex the sperminium cation is disordered and partially invisible in electron-density maps. In the Z-DNA-Zn(2+) complex the sperminium cation only interacts with the phosphate groups of the Z-DNA molecules, while in the Z-DNA-Mn(2+) structure it forms hydrogen bonds to both the phosphate groups and DNA bases.

Association between environmental tobacco smoke exposure and lung cancer susceptibility: modification by antioxidant enzyme genetic polymorphisms.

PubMed

Fathy, Mona; Hamed, Mai; Youssif, Omnia; Fawzy, Nahla; Ashour, Wafa

2014-02-01

Environmental tobacco smoke (ETS) is the primary etiologic factor responsible for lung cancer. However, only 10-15 % of smokers develop lung cancer, suggesting a genetic role in modifying individual susceptibility to lung cancer. Antioxidant enzymes and genetic polymorphisms should be considered. The present study aimed to evaluate the role of antioxidant enzyme activity and genetic polymorphisms in modifying the susceptibility to lung cancer among individuals exposed to ETS. A total of 150 male subjects were divided into three groups: 50 lung cancer patients, 50 chronic smokers, and 50 passive smokers. Genotyping of microsomal epoxide hydrolase (mEH) exon 3 (Tyr(113)Hist) and exon 4 (Hist(139)Arg) polymorphisms were done by the polymerase chain reaction-restriction fragment length polymorphism technique. MnSOD (Val(16)Ala) polymorphism was detected by the real time-TaqMan assay. Erythrocyte MnSOD activity was measured spectrophotometrically. ETS-exposed individuals (both active and passive smokers) who carried the His allele of mEH exon3 have a 2.9-fold increased risk of lung cancer (odds ratio [OR] 2.9, P < 0.001). In addition, ETS-exposed carriers of the Arg allele of mEH exon 4 have a 2.1-fold increased risk of lung cancer (OR 2.1, P = 0.024). However, no association between the MnSOD Val(16)Ala polymorphism and lung cancer was detected among ETS-exposed individuals (OR 1.6, P = 0.147), although the lung cancer group had significantly lower MnSOD activity than the chronic or passive smoker groups (P = 0.03). Exons 3 and 4 polymorphisms of the mEH gene may contribute to lung cancer susceptibility through disturbed antioxidant balance. However, this was not the case with the MnSOD Val(16)Ala single-nucleotid polymorphism. Antioxidant enzymes may modulate the influence of ETS exposure on lung cancer risk.

Honeycomb-like S = 5/2 Spin–Lattices in Manganese(II) Vanadates

DOE PAGES

Sanjeewa, Liurukara. D.; McGuire, Michael A.; McMillen, Colin D.; ...

2016-08-26

We synthesized new complex manganese vanadate materials as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. We grew one compound, Mn 5(VO 4) 2(OH) 4, from Mn 2O 3 and V 2O 5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn 6O(VO 4) 2(OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn 5(VO 4) 2(OH) 4: C2/m, Z = 2, a = 9.6568(9) Å, b = 9.5627(9) Å, c = 5.4139(6) Å, β = 98.529(8)°; Mn 6O(VOmore » 4) 2(OH): P21/m, Z = 2, a = 8.9363(12) Å, b = 6.4678(8) Å, c = 10.4478(13) Å, β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn 5(VO 4) 2(OH) 4 possesses complex honeycomb-type Mn–O layers, built from edge-sharing [MnO 6] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn 6O(VO 4) 2(OH) presents a more complicated structure with both octahedral [MnO 6] and trigonal bipyramidal [MnO 5] units. A different pattern of planar honeycomb sheets are formed by edge-shared [MnO6] octahedra, and these sublattices are connected through edge-shared dimers of [MnO 5] trigonal bipyramids to form corrugated sheets. Vanadate groups again condense the sheets into a three-dimensional framework. Infrared and Raman spectroscopies indicated the presence of OH groups and displayed characteristic Raman scattering due to vanadate groups. Furthermore, temperature-dependent magnetic studies indicated Curie–Weiss behavior above 100 K with significant anti-ferromagnetic coupling for both compounds, with further complex magnetic behavior at lower temperatures. The data indicate canted anti-ferromagnetic order below 57 K in Mn 5(VO 4) 2(OH) 4 and below 45 K in Mn 6O(VO 4) 2(OH). Members of another class of compounds, K 2M 3(VO 4) 2(OH) 2 (M = Mn, Co), also containing a honeycomb-type sublattice, were also synthesized to allow a comparison of the structural features across all three structure types and to demonstrate extension to other transition metals.« less

Spin resolved photoelectron spectroscopy of [Mn6IIICrIII]3 + single-molecule magnets and of manganese compounds as reference layers

NASA Astrophysics Data System (ADS)

Helmstedt, Andreas; Müller, Norbert; Gryzia, Aaron; Dohmeier, Niklas; Brechling, Armin; Sacher, Marc D.; Heinzmann, Ulrich; Hoeke, Veronika; Krickemeyer, Erich; Glaser, Thorsten; Bouvron, Samuel; Fonin, Mikhail; Neumann, Manfred

2011-07-01

Properties of the manganese-based single-molecule magnet [\\mathbf {Mn}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}_{\\mathbf {6}} \\mathbf {Cr}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}]^{\\mathbf {3} \\boldsymbol {+}} are studied. It contains six MnIII ions arranged in two bowl-shaped trinuclear triplesalen building blocks linked by a hexacyanochromate and exhibits a large spin ground state of St = 21/2. The dominant structures in the electron emission spectra of [\\mathbf {Mn}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}_{\\mathbf {6}}\\mathbf {Cr}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}]^{\\mathbf {3} \\boldsymbol {+}} resonantly excited at the L3-edge are the L3M2, 3M2, 3, L3M2, 3V and L3VV Auger emission groups following the decay of the primary p3/2 core hole state. Significant differences of the Auger spectra from intact and degraded [\\mathbf {Mn}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}_{\\mathbf {6}}\\mathbf {Cr}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}]^{\\mathbf {3} \\boldsymbol {+}} show up. First measurements of the electron spin polarization in the L3M2, 3V and L3VV Auger emission peaks from the manganese constituents in [\\mathbf {Mn}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}_{\\mathbf {6}} \\mathbf {Cr}^{\\mathbf {I}\\mathbf {I}\\mathbf {I}}]^{\\mathbf {3} \\boldsymbol {+}} resonantly excited at the L3-edge near 640 eV by circularly polarized synchrotron radiation are reported. In addition spin resolved Auger electron spectra of the reference substances MnO, Mn2O3 and MnII(acetate)2·4H2O are given. The applicability of spin resolved electron spectroscopy for characterizing magnetic states of constituent atoms compared to magnetic circular dichroism (MCD) is verified: the spin polarization obtained from MnII(acetate)2·4H2O at room temperature in the paramagnetic state compares to the MCD asymmetry revealed for a star-shaped molecule with a Mn4IIO6 core at 5 K in an external magnetic field of 5 T.

Rhombohedral to Cubic Conversion of GeTe via MnTe Alloying Leads to Ultralow Thermal Conductivity, Electronic Band Convergence, and High Thermoelectric Performance.

PubMed

Zheng, Zheng; Su, Xianli; Deng, Rigui; Stoumpos, Constantinos; Xie, Hongyao; Liu, Wei; Yan, Yonggao; Hao, Shiqiang; Uher, Ctirad; Wolverton, Chris; Kanatzidis, Mercouri G; Tang, Xinfeng

2018-02-21

In this study, a series of Ge 1-x Mn x Te (x = 0-0.21) compounds were prepared by a melting-quenching-annealing process combined with spark plasma sintering (SPS). The effect of alloying MnTe into GeTe on the structure and thermoelectric properties of Ge 1-x Mn x Te is profound. With increasing content of MnTe, the structure of the Ge 1-x Mn x Te compounds gradually changes from rhombohedral to cubic, and the known R3m to Fm-3m phase transition temperature of GeTe moves from 700 K closer to room temperature. First-principles density functional theory calculations show that alloying MnTe into GeTe decreases the energy difference between the light and heavy valence bands in both the R3m and Fm-3m structures, enhancing a multiband character of the valence band edge that increases the hole carrier effective mass. The effect of this band convergence is a significant enhancement in the carrier effective mass from 1.44 m 0 (GeTe) to 6.15 m 0 (Ge 0.85 Mn 0.15 Te). In addition, alloying with MnTe decreases the phonon relaxation time by enhancing alloy scattering, reduces the phonon velocity, and increases Ge vacancies all of which result in an ultralow lattice thermal conductivity of 0.13 W m -1 K -1 at 823 K. Subsequent doping of the Ge 0.9 Mn 0.1 Te compositions with Sb lowers the typical very high hole carrier concentration and brings it closer to its optimal value enhancing the power factor, which combined with the ultralow thermal conductivity yields a maximum ZT value of 1.61 at 823 K (for Ge 0.86 Mn 0.10 Sb 0.04 Te). The average ZT value of the compound over the temperature range 400-800 K is 1.09, making it the best GeTe-based thermoelectric material.

Integrating forest management for wildlife and fish: 1987 Society of American Foresters national convention; 1987 October 18-21; Minneapolis, MN.

Treesearch

USDA FS

1988-01-01

Papers from a technical session working group of the 1987 Society of American Foresters national convention. Topics include ecological and economic considerations of integrated forest resource management.

Pentanuclear heterometallic {Mn(III)(2)Ln(3)} (Ln = Gd, Dy, Tb, Ho) assemblies in an open-book type structural topology: appearance of slow relaxation of magnetization in the Dy(III) and Ho(III) analogues.

PubMed

Bag, Prasenjit; Chakraborty, Amit; Rogez, Guillaume; Chandrasekhar, Vadapalli

2014-07-07

The reaction of Ln(III) nitrate and Mn(ClO4)2·6H2O salts in the presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the isolation of four isostructural pentanuclear hetereometallic complexes [Mn(III)2Gd3(LH)4(NO3)(HOCH3)]ClO4·NO3 (1), [Mn(III)2Dy3(LH)4(NO3)(HOCH3)]ClO4·NO3 (2), [Mn(III)2Tb3(LH)4(NO3)(HOCH3)]ClO4·NO3 (3), and [Mn(III)2Ho3(LH)4(NO3)(HOCH3)]ClO4·NO3 (4) with an open-book type structural topology. 1-4 are dicationic and crystallize in the achiral space group, P21/n. A total of four triply deprotonated ligands, [LH](3-), are involved in holding the pentameric metal framework, {Mn(III)2Ln3}. In these complexes both the lanthanide and the manganese(III) ions are doubly bridged, involving phenolate or ethoxide oxygen atoms. The magnetochemical analysis reveals the presence of global antiferromagnetic interactions among the spin centers at low temperatures in all the four compounds. AC susceptibility measurements show the presence of temperature dependent out-of-phase ac signal for compounds 2 and 4 indicating an SMM behavior.

An unusual stable mononuclear Mn(III) bis-terpyridine complex exhibiting Jahn-Teller compression: electrochemical synthesis, physical characterisation and theoretical study.

PubMed

Romain, Sophie; Duboc, Carole; Neese, Frank; Rivière, Eric; Hanton, Lyall R; Blackman, Allan G; Philouze, Christian; Leprêtre, Jean-Claude; Deronzier, Alain; Collomb, Marie-Noëlle

2009-01-01

The mononuclear manganese bis-terpyridine complex [Mn(tolyl-terpy)(2)](X)(3) (1(X)(3); X=BF(4), ClO(4), PF(6); tolyl-terpy=4'-(4-methylphenyl)-2,2':6',2"-terpyridine), containing Mn in the unusual +III oxidation state, has been isolated and characterised. The 1(3+) ion is a rare example of a mononuclear Mn(III) complex stabilised solely by neutral N ligands. Complex 1(3+) is obtained by electrochemical oxidation of the corresponding Mn(II) compound 1(2+) in anhydrous acetonitrile. Under these conditions the cyclic voltammogram of 1(2+) exhibits not only the well-known Mn(II)/Mn(III) oxidation at E(1/2)=+0.91 V versus Ag/Ag(+) (+1.21 V vs. SCE) but also a second metal-based oxidation process corresponding to Mn(III)/Mn(IV) at E(1/2)=+1.63 V (+1.93 V vs. SCE). Single crystals of 1(PF(6))(3)2 CH(3)CN were obtained by an electrocrystallisation procedure. X-ray analysis unambiguously revealed its tetragonally compressed octahedral geometry and high-spin character. The electronic properties of 1(3+) were investigated in detail by magnetic measurements and theoretical calculations, from which a D value of +4.82 cm(-1) was precisely determined. Density functional and complete active space self consistent field ab initio calculations both correctly predict a positive sign of D, in agreement with the compressed tetragonal distortion observed in the X-ray structure of 1(PF(6))(3)2 CH(3)CN. The different contributions to D were calculated, and the results show that 1) the spin-orbit coupling part (+2.593 cm(-1)) is predominant compared to the spin-spin interaction (+1.075 cm(-1)) and 2) the excited triplet states make the dominant contribution to the total D value.

Impact of open manganese mines on the health of children dwelling in the surrounding area

PubMed Central

Duka, Ykateryna D.; Ilchenko, Svetlana I.; Kharytonov, Mykola M.; Vasylyeva, Tetyana L.

2011-01-01

Introduction: Chronic manganese (Mn) exposure is a health hazard associated with the mining and processing of Mn ores. Children living in an area with increased environmental exposure to Mn may have symptoms of chronic toxicity that are different from adults who experience occupational exposure. The aim of the study was to compare health outcomes in a pediatric population living near open Mn mines with a group of children from a reference area and then to develop and implement preventive/rehabilitation measures to protect the children in the mining region. Methods: After environmental assessment, a group of 683 children living in a Mn-rich region of Ukraine were screened by clinical evaluation, detection of sIgA (37 children), micronucleus analysis (56 children), and hair Mn content (166 children). Results: Impaired growth and rickets-like skeletal deformities were observed in 33% of the children. This was a significantly higher percentage than in children in the reference region (15%). The children from the Mn-mining region also had increased salivary levels of immunoglobulin A (104.4±14.2 mcg/ml vs. 49.7±6.1 mcg/ml among the controls (p<0.05), increased serum alpha 1 proteinase inhibitor levels (4.93±0.21 g/l compared with 2.91±0.22 g/l for controls; p<0.001) and greater numbers of micronuclei in the mucous cells of the oral cavity (0.070±0.008 vs. 0.012±0.009, p<0.001). Conclusions: These findings indicate the deleterious health consequences of living in a Mn-mining area. Medical rehabilitation programs were conducted and produced positive results, but further validation of their effectiveness is required. The study provided background information to formulate evidence-based decisions about public health in a region of high Mn exposure. PMID:24149028

Structural comparative studies on new Mn(II), Cr(III) and Ru(III) complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ).

PubMed

Al-Assy, Waleed H; El-Askalany, Abdel Moneum H; Mostafa, Mohsen M

2013-12-01

The structure of a new Mn(II) complex, [Mn(TPTZ)Cl2(H2O)]⋅H2O, was established by a single crystal X-ray diffraction. Crystal data are as follow: monoclinic, P21/c,a = 8.7202 (3)Å, b = 11.5712 (4)Å, c = 20.8675 (9)Å, β=11 (18) × 1010, V = 2029.27 (13)Å(3), Z = 4. The HOMO, LUMO and other DFT parameters on the atoms have been calculated to confirm the geometry of the ligand and its complexes using material studio program. The complexes were characterized by elemental analyses, spectral, magnetic, thermal and cyclic voltammetry measurements. Electronic spectra and magnetic moments of the complexes suggest distorted-octahedral structures around the metal ions (Mn(II), Cr(III) and Ru(III)). The redox properties were investigated by cyclic voltammetry. Kinetic parameters were determined using Coats-Redfern and Horowitz-Metzger methods. The results of DNA studies of the metal complexes promised to be effective in tumour treatment. Copyright © 2013 Elsevier B.V. All rights reserved.

Structural comparative studies on new MnII, CrIII and RuIII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ)

NASA Astrophysics Data System (ADS)

Al-Assy, Waleed H.; El-Askalany, Abdel Moneum H.; Mostafa, Mohsen M.

2013-12-01

The structure of a new MnII complex, [Mn(TPTZ)Cl2(H2O)]ṡH2O, was established by a single crystal X-ray diffraction. Crystal data are as follow: monoclinic, P21/c, a = 8.7202 (3) Å, b = 11.5712 (4) Å, c = 20.8675 (9) Å, β = 11 (18) × 1010, V = 2029.27 (13) Å3, Z = 4. The HOMO, LUMO and other DFT parameters on the atoms have been calculated to confirm the geometry of the ligand and its complexes using material studio program. The complexes were characterized by elemental analyses, spectral, magnetic, thermal and cyclic voltammetry measurements. Electronic spectra and magnetic moments of the complexes suggest distorted-octahedral structures around the metal ions (MnII, CrIII and RuIII). The redox properties were investigated by cyclic voltammetry. Kinetic parameters were determined using Coats-Redfern and Horowitz-Metzger methods. The results of DNA studies of the metal complexes promised to be effective in tumour treatment.

White LED based on CaAl2Si2O8:Eu2+ Mn2+ phosphor and CdS/ZnS quantum dots

NASA Astrophysics Data System (ADS)

Shen, Changyu; Zhong, Chuan; Hou, Qianglong; Li, Ke

2011-02-01

Core/shell CdS/ZnS quantum dots (QDs) with the emission wavelength of 610nm, was synthesized by thermal deposition using cadmium oxide and selenium as precursors in a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. CaAl2Si2O8:Eu2+ Mn2+ phosphor was synthesized by high-temperature solid state reaction at 1290 °C for 2 hours under the H2 reducing atmosphere, and X-ray powder diffraction analysis confirmed the formation of it. It has two emission bands peaking at 420 nm and 580nm originated from the transition 5d to 4f of Eu2+ and 4T1-6A1 of Mn2+, respectively. Blends of CaAl2Si2O8:Eu2+,Mn2+ phosphor and CdS/ZnS QDs exhibited the prominent spectral evolution with an increasing content of QDs. A hybrid white LED, which combines a blue LED with the blend of CaAl2Si2O8:Eu2+ Mn2+ phosphor and QDs with a weight ratio of 2:1, with the CIE coordinate of (0.3183, 0.3036) and CRI of 85 was obtained.

Quantification of changes in metal loading from storm runoff, Merse River (Tuscany, Italy)

USGS Publications Warehouse

Kimball, B.A.; Bianchi, F.; Walton-Day, K.; Runkel, R.L.; Nannucci, M.; Salvadori, A.

2007-01-01

The Merse River in Tuscany is affected by mine drainage and the weathering of mine wastes along several kilometres of its catchment. The metal loading to the stream was quantified by defining detailed profiles of discharge and concentration, using tracer-dilution and synoptic-sampling techniques. During the course of a field experiment to evaluate metal loading to the Merse, such data were obtained for both storm and pre-storm conditions, providing a unique opportunity for comparison. Iron, Cu, and Mn were chosen to illustrate changes resulting from the storm. The total-recoverable load of Fe increased 21-fold, while loads of Cu and Mn increased by 8- and 7-fold, respectively, during the storm runoff. The increases most likely resulted from flushing particulates from near the stream, resuspension of colloidal material from the streambed, and increased ground-water inflow to the stream. The increases in Cu and Mn loads results from their association with colloids. It is possible that in-stream colloids had relatively more Cu than Mn, while near-stream colloids had relatively more Mn. Each of the metals also increased as a result of increased ground-water discharge during the storm. Despite great increases in load, the filterable concentrations of these metals did not increase substantially, remaining below chronic levels of toxicity. ?? 2007 Springer-Verlag.

77 FR 2083 - Notice of Inventory Completion: Minnesota Indian Affairs Council, Bemidji, MN

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-13

... the north side of Height of Land Lake, site 21BK48, by Mr. William Krause during road construction and... near Ice Cracking Lake during road construction and donated to the Becker County Historical Society (HR...

Heterogeneous Reaction of SO2 on Manganese Oxides: the Effect of Crystal Structure and Relative Humidity.

PubMed

Yang, Weiwei; Zhang, Jianghao; Ma, Qingxin; Zhao, Yan; Liu, Yongchun; He, Hong

2017-07-03

Manganese oxides from anthropogenic sources can promote the formation of sulfate through catalytic oxidation of SO 2 . In this study, the kinetics of SO 2 reactions on MnO 2 with different morphologies (α, β, γ and δ) was investigated using flow tube reactor and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). Under dry conditions, the reactivity towards SO 2 uptake was highest on δ-MnO 2 but lowest on β-MnO 2 , with a geometric uptake coefficient (γ obs ) of (2.42 ± 0.13) ×10 -2 and a corrected uptake coefficient (γ c ) of (1.48 ± 0.21) ×10 -6 for the former while γ obs of (3.35 ± 0.43) ×10 -3 and γ c of (7.46 ± 2.97) ×10 -7 for the latter. Under wet conditions, the presence of water altered the chemical form of sulfate and was in favor for the heterogeneous oxidation of SO 2 . The maximum sulfate formation rate was reached at 25% RH and 45% for δ-MnO 2 and γ-MnO 2 , respectively, possibly due to their different crystal structures. The results suggest that morphologies and RH are important factors influencing the heterogeneous reaction of SO 2 on mineral aerosols, and that aqueous oxidation process involving transition metals of Mn might be a potential important pathway for SO 2 oxidation in the atmosphere.

Quick and enhanced degradation of bisphenol A by activation of potassium peroxymonosulfate to SO4rad - with Mn-doped BiFeO3 nanoparticles as a heterogeneous Fenton-like catalyst

NASA Astrophysics Data System (ADS)

Soltani, Tayyebeh; Tayyebi, Ahmad; Lee, Byeong-Kyu

2018-05-01

Mn-doped BiFeO3 magnetic nanoparticles (BFO MNPs), namely BiFe1-xMnxO3 (x = 0.05 and 0.10), were successfully synthesized using a simple and novel sol-gel method and then applied as a highly efficient peroxymonosulfate (KHSO5, PMS) activation catalyst for the fast degradation of bisphenol A (BPA) from aqueous solution. The strong PMS activation ability of 10% Mn-doped BFO MNPs without any metal leaching due to the simultaneous effects of iron and manganese ions in the production of radical sulfate (SO4rad -), caused complete BPA degradation in 15 min, which was much faster than that using combinations with H2O2. TOC was reduced to 33%, 23% and 13% by PMS activated with BFO, 5 and 10% Mn doped BFO, respectively, which are 2.1, 2.6 and 3.15-fold lower than that same nanoparticles activated with H2O2. The photocatalytic mechanism of BPA with the simultaneous effects of iron and manganese ions in Mn-doped BFO was explored. The addition of KBrO3 and NaNO3 salts into Mn-doped BFO/PMS system reduced the complete BPA degradation time to 10 min, whereas Na2CO3 and NaCl salt addition retarded it, because salt addition can generate radical species that are either more or less active than SO4rad -.

Assessing Selenium, Manganese, and Iodine Status in Pediatric Patients Receiving Parenteral Nutrition.

PubMed

Johnsen, Jacob Clarke; Reese, Susan Anne; Mackay, Mark; Anderson, Collin R; Jackson, Daniel; Paul, Irasema Libertad

2017-08-01

Pediatric patients who are receiving parenteral nutrition (PN) unsupplemented with trace minerals can become deficient. Due to shortages in trace mineral products and the 2004 American Society for Parenteral and Enteral Nutrition report stating that individualized trace element supplementation may be warranted, a review was conducted concerning the trace minerals selenium (Se), manganese (Mn), and iodine (I). A retrospective review of pediatric patients receiving PN that contained Se and Mn was conducted to determine if a difference existed between them and patients receiving PN without Se and Mn. Statistical analysis was done to assess a difference between trace mineral levels and the time to deficiency between supplemented and unsupplemented patients. Unsupplemented I patients had urine I levels assessed to determine deficiencies in patients receiving PN. Plasma Se levels were measured at a mean of 20 days for supplemented patients (n = 131) and 19 days for nonsupplemented patients (n = 57) with no difference between groups ( P = .2973). Plasma Mn levels were measured at a mean of 28 days, showing no statistical difference ( P = .721). Of the 177 nonsupplemented I patients, 74% demonstrated I deficiencies without supplementation. Time to the development of a Se, Mn, or I deficiency is important to guide supplementation of exclusive PN in children when trace mineral products are short in supply. Our retrospective experience supports assessment of the trace minerals Se at 21 days and Mn at 30 days. It also suggests that some pediatric patients receiving PN are deficient in I.

Tectonic pumping: earthquake-induced chemical flux detected in situ by a submarine cable experiment in Sagami Bay, Japan

PubMed Central

Gamo, Toshitaka; Okamura, Kei; Mitsuzawa, Kyohiko; Asakawa, Kenichi

2007-01-01

We successfully deployed an in situ automatic chemical analyzer sensitive to manganese (Mn) in seawater for a period of 81 days for the first time on the deep seafloor of Sagami Bay along a convergent plate boundary south of Japan. The in situ Mn analyzer (GAMOS-IV) was connected to a submarine cable as a means to supply power and to relay real time data. During the observation period from April 5 till June 25, 2006, the amount of measured Mn was seen to increase abruptly up to 10 times that of the background level only on April 21, probably triggered by a M5.8 earthquake which occurred ∼7 km south-southwest of the observation site. This study demonstrates the suitability of submarine cables for the long-term geochemical monitoring of deep sea environments. PMID:24367146

catena-Poly[[[aqua­(2,2′-bipyridine)manganese(II)]-μ-5-methoxy­iso­phthalato-κ3 O,O′:O′′] monohydrate

PubMed Central

Shen, Su-Mei

2009-01-01

In the title compound, {[Mn(C8H4O4)(C10H8N2)(H2O)]·H2O}n, the MnII centre is octa­hedrally coordinated by three O atoms from two 5-methoxy­isophthalate (CH3O-ip) ligands, a fourth from a coordinated water mol­ecule and two N atoms from one chelating 2,2′-bipyridine (2,2-bipy) ligand. Each pair of adjacent MnII atoms is bridged by a CH3O-ip ligand, forming a helical chain running along a crystallographic 21 axis in the c-axis direction. These chains are decorated with 2,2′-bipy ligands on alternating sides. O—H⋯O hydrogen bonding involving the water molecules stabilizes the crystal structure. PMID:21577709

Photoluminescence and afterglow luminescence properties of a green-emitting Na2BeGeO4:Mn2+ phosphor

NASA Astrophysics Data System (ADS)

Lu, Jie; Shen, Linjiang

2018-07-01

Recently, developing free rare-earth (RE) doped afterglow phosphors has received great attentions in the lighting field. In this work, we prepare and report a RE-free phosphor, Na2BeGeO4:Mn2+, which can simultaneously emit the green fluorescence and afterglow luminescence upon excitation at UV light. Our results reveal that the as-prepared samples crystallize in orthorhombic type with the space group of Pmn21 (31). The green emission is a broad band centered at 525 nm, corresponds to the 4T1(4G)-6A1(6S) transition of Mn2+ ions. After exposing to a 254 nm UV lamp for 10 min, the green afterglow luminescence seen with naked eyes can last more than 5 h. Together with the structural analysis and thermoluminescence (TL) spectra, the afterglow luminescence mechanism is also discussed in this work.

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

NASA Astrophysics Data System (ADS)

Vinodh Kumar, S.; Seenithurai, S.; Manivel Raja, M.; Mahendran, M.

2015-10-01

Polycrystalline Ni-Mn-Ga ferromagnetic shape-memory thin films have been deposited on Si (100) substrates using a direct-current magnetron sputtering technique. The microstructure and the temperature dependence of magnetic properties of the films have been investigated by x-ray diffraction, scanning electron microscopy, and thermomagnetic measurements. As-deposited Ni50.2Mn30.6Ga19.2 film showed quasi-amorphous structure with paramagnetic nature at room temperature. When annealed at 873 K, the quasi-amorphous film attained crystallinity and possessed L21 cubic ordering with high magnetic transition temperature. Saturation magnetization and coercivity values for the annealed film were found to be 220 emu/cm3 and 70 Oe, respectively, indicating soft ferromagnetic character with low magnetocrystalline anisotropy. The magnetic transitions of the film deposited at 100 W were above room temperature, making this a potential candidate for use in microelectromechanical system devices.

Enhanced magnetic hysteresis in Ni-Mn-Ga single crystal and its influence on magnetic shape memory effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heczko, O., E-mail: heczko@fzu.cz; Drahokoupil, J.; Straka, L.

2015-05-07

Enhanced magnetic hysteresis due to boron doping in combination with magnetic shape memory effect in Ni-Mn-Ga single crystal results in new interesting functionality of magnetic shape memory (MSM) alloys such as mechanical demagnetization. In Ni{sub 50.0}Mn{sub 28.5}Ga{sub 21.5} single crystal, the boron doping increased magnetic coercivity from few Oe to 270 Oe while not affecting the transformation behavior and 10 M martensite structure. However, the magnetic field needed for MSM effect also increased in doped sample. The magnetic behavior is compared to undoped single crystal of similar composition. The evidence from the X-ray diffraction, magnetic domain structure, magnetization loops, and temperature evolutionmore » of the magnetic coercivity points out that the enhanced hysteresis is caused by stress-induced anisotropy.« less

Magneto-optical spectroscopy of ferromagnetic shape-memory Ni-Mn-Ga alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veis, M., E-mail: veis@karlov.mff.cuni.cz; Beran, L.; Zahradnik, M.

2014-05-07

Magneto-optical properties of single crystal of Ni{sub 50.1}Mn{sub 28.4}Ga{sub 21.5} magnetic shape memory alloy in martensite and austenite phase were systematically studied. Crystal orientation was approximately along (100) planes of parent cubic austenite. At room temperature, the sample was in modulated 10M martensite phase and transformed to cubic austenite at 323 K. Spectral dependence of polar magneto-optical Kerr effect was obtained by generalized magneto-optical ellipsometry with rotating analyzer in the photon energy range from 1.2 to 4 eV, and from room temperature to temperature above the Curie point. The Kerr rotation spectra exhibit prominent features typical for complexes containing Mn atoms. Significantmore » spectral changes during transformation to austenite can be explained by different optical properties caused by changes in density of states near the Fermi energy.« less

Content and distribution of macro- and micro-elements in the body of pasture-fed young horses.

PubMed

Grace, N D; Pearce, S G; Firth, E C; Fennessy, P F

1999-03-01

To determine the content and distribution of Na, K, Ca, P, Mg, S, Cu, Mn, Fe and Zn in the body of pasture-fed young horses and then use a factorial model to calculate the dietary mineral requirements for growth. Twenty-one foals were killed at about 150 days of age and the organs, soft tissues, skin and bones and a sample of muscle were dissected out and weighted. The mineral concentrations of elements in all soft tissues and bones were measured by inductively coupled emission spectrometry. The total mineral element composition associated with a tissue was determined from the weight of tissue and its mineral element concentration. Expressed as a percent of total body mineral elements, muscle contained 20% Na, 78% K, 32% Mg, 62% Cu, 36% Mn and 57% Zn, bone contained 47% Na, 99% Ca, 81% P, 62% Mg, 30% Mn and 28% Zn while the organs accounted for a smaller percentage ranging from 0.06% for Ca to 26% for Fe. In liver Cu accounted for 9.2% of total body Cu. Each kilogram of empty body weight was associated with 1.0 g Na, 2.5 g K, 17.1 g Ca, 10.1 g P, 0.4 g Mg, 1.1 mg Cu, 0.39 mg Mn, 52.5 mg Fe and 21.4 mg Zn. The mineral element content of body weight gain is a component used in the factorial model to determine dietary mineral element requirements for growth. The calculated dietary mineral requirements, expressed per kg dry matter, for a 200 kg horse gaining 1.0 kg/day were 1.0 g Na, 2.1 g K, 4.6 g Ca, 3.5 g P, 0.7 g Mg, 4.5 mg Cu and 25 mg Zn.

Temperature dependence of local structural changes around transition metal centers Cr3+ and Mn2+ in RAl3(BO3)4 crystals studied by EMR

NASA Astrophysics Data System (ADS)

Açıkgöz, Muhammed; Rudowicz, Czesław; Gnutek, Paweł

2017-11-01

Theoretical investigations are carried out to determine the temperature dependence of the local structural parameters of Cr3+ and Mn2+ ions doped into RAl3(BO3)4 (RAB, R = Y, Eu, Tm) crystals. The zero-field splitting (ZFS) parameters (ZFSPs) obtained from the spin Hamiltonian (SH) analysis of EMR (EPR) spectra serve for fine-tuning the theoretically predicted ZFSPs obtained using the semi-empirical superposition model (SPM). The SPM analysis enables to determine the local structure changes around Cr3+ and Mn2+ centers in RAB crystals and explain the observed temperature dependence of the ZFSPs. The local monoclinic C2 site symmetry of all Al sites in YAB necessitates consideration of one non-zero monoclinic ZFSP (in the Stevens notation, b21) for Cr3+ ions. However, the experimental second-rank ZFSPs (D =b20 , E = 1 / 3b22) were expressed in a nominal principal axis system. To provide additional insight into low symmetry aspects, the distortions (ligand's distances ΔRi and angular distortions Δθi) have been varied while preserving monoclinic site symmetry, in such way as to obtain the calculated values (D, E) close to the experimental ones, while keeping b21 close to zero. This procedure yields good matching of the calculated ZFSPs and the experimental ones, and enables determination of the corresponding local distortions. The present results may be useful in future studies aimed at technological applications of the Huntite-type borates with the formula RM3(BO3)4. The model parameters determined here may be utilized for ZFSP calculations for Cr3+ and Mn2+ ions at octahedral sites in single-molecule magnets and single-chain magnets.

Self-encapsulation of [MII(phen)2(H2O)2]2+ (M=Co, Zn) in one-dimensional nanochannels of [MII(H2O)6(BTC)2]4- (M=Co, Cu, Mn): a high HQ/CAT ratio catalyst for hydroxylation of phenols.

PubMed

Bi, Jianhong; Kong, Lingtao; Huang, Zixiang; Liu, Jinhuai

2008-06-02

Four novel three-dimensional (3D) microporous supramolecular compounds containing nanosized channels, namely, [Co(phen)2(H2O)2]2[Co(H2O)6].2BTC.21.5H2O (1), [Co(phen)2(H2O)2]2[Cu(H2O)6].2BTC.21.5H2O (2), [Co(phen)2(H2O)2]2[Mn(H2O)6].2BTC.18H2O (3), and [Zn(phen)2(H2O)2]2[Mn(H2O)6].2BTC.22.5H2O (4), were synthesized from 1,3,5-benzenetricarboxylate (BTC), 1,10-phenanthroline (phen), and the transition-metal salt(s) by self-assembly. Single-crystal X-ray structural analysis showed that the resulting 3D microporous supramolecular frameworks consist of a two-dimensional (2D) hydrogen-bonded host framework of [MII(H2O)6(BTC)2]4- (M=Co for 1, Cu for 2, Mn for 3, 4) with rectangular-shaped cavities containing [MII(phen)2(H2O)2]2+ (M=Co for 1-3, Zn for 4) guests. The guest complex is encapsulated in the 2D hydrogen-bonded host framework by hydrogen bonding and aromatic pi-pi stacking interactions, forming the 3D hydrogen-bonded framework. The catalytic activities of 1, 2, 3, and 4 were studied using hydroxylation of phenols with 30% aqueous H2O2 as a test reaction. The compounds displayed a good phenol conversion ratio and excellent channel selectivity in the hydroxylation reaction, with a maximum hydroquinone (HQ)/catechol (CAT) ratio of 3.9.

Mitochondrial MnSOD mRNA expression in human chorioamniotic membranes and its association with labor, inflammation and infection

PubMed Central

Than, Nandor Gabor; Romero, Roberto; Tarca, Adi L.; Draghici, Sorin; Erez, Offer; Chaiworapongsa, Tinnakorn; Kim, Yeon Mee; Kim, Sun Kwon; Vaisbuch, Edi; Tromp, Gerard

2010-01-01

Objective Human parturition is characterized by the activation of genes involved in acute inflammatory in the fetal membranes. Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme that scavenges reactive oxygen species (ROS). MnSOD is up-regulated in sites of inflammation and has an important role in the down-regulation of acute inflammatory processes. Therefore, the aim of this study was to determine the differences in MnSOD mRNA expression in the fetal membranes in patients with term and preterm labor as well as in acute chorioamnionitis. Study design Fetal membranes were obtained from patients in the following groups: 1) term not in labor (n=29); 2) term in labor (n=29); 3) spontaneous preterm labor with intact mebranes (n=16); 4) PTL with histological chorioamnionitis (n=12); 5) preterm prelabor rupture of membranes (PPROM; n=17); and 6) PPROM with histological chorioamnionitis (n=21). MnSOD mRNA expression in the membranes was determined by quantitative real-time RT-PCR. Results 1) MnSOD mRNA expression was higher in the fetal membranes of patients at term in labor than those not in labor (2.4-fold; p=0.02); 2) the amount of MnSOD mRNA in the fetal membranes was higher in PTL than in term labor or in PPROM (7.2-fold, p=0.03; 3.2-fold, p=0.03, respectively); 3) MnSOD mRNA expression was higher when histological chorioamnionitis was present both among patients with PPROM (3.8-fold, p=0.02) and with PTL (5.4-fold, p=0.02) than in patients with these conditions without histological chorioamnionitis; 4) expression of MnSOD mRNA was higher in PTL with chorioamnionitis than in PPROM with chorioamnionitis (4.3-fold, p=0.03); Conclusion The increase in MnSOD mRNA expression by fetal membranes in term labor and in histological chorioamnionitis in PTL and PPROM suggests that the fetus deploys anti-oxidant mechanisms to constrain the inflammatory processes in the chorioamniotic membranes. PMID:19900038

ECOTOX (ECOTOXICOLOGY DATABASE): AN ASSESSMENT TOOL FOR THE 21ST CENTURY

EPA Science Inventory

The ECOTOX (ECOTOXicology Database) system developed by the U.S. EPA, National Health and Environmental Effecrs Research Laboratory (NHEERL), Mid-Continent Ecology Division in Duluth, MN, (MED-Duluth), provides a web browser search interface for locating aquatic and terrestrial t...

Strangeness and charmness content of the nucleon from overlap fermions on 2+1-flavor domain-wall fermion configurations

NASA Astrophysics Data System (ADS)

Gong, M.; Alexandru, A.; Chen, Y.; Doi, T.; Dong, S. J.; Draper, T.; Freeman, W.; Glatzmaier, M.; Li, A.; Liu, K. F.; Liu, Z.

2013-07-01

We present a calculation of the strangeness and charmness contents ⟨N|s¯s|N⟩ and ⟨N|c¯c|N⟩ of the nucleon from dynamical lattice QCD with 2+1 flavors. The calculation is performed with overlap valence quarks on 2+1-flavor domain-wall fermion gauge configurations. The configurations are generated by the RBC collaboration on a 243×64 lattice with sea-quark mass aml=0.005, ams=0.04, and inverse lattice spacing a-1=1.73GeV. Both actions have chiral symmetry which is essential in avoiding contamination due to the operator mixing with other flavors. The nucleon propagator and the quark loops are both computed with stochastic grid sources, while low-mode substitution and low-mode averaging methods are used respectively which substantially improve the signal-to-noise ratio. We obtain the strangeness matrix element fTs=ms⟨N|s¯s|N⟩/MN=0.0334(62), and the charmness content fTc=mc⟨N|c¯c|N⟩/MN=0.094(31) which is resolved from zero by 3σ precision for the first time.

Study of the Thermodynamics of Chromium(III) and Chromium(VI) Binding to Fe3O4 and MnFe2O4 nanoparticles

PubMed Central

Luther, Steven; Brogfeld, Nathan; Kim, Jisoo; Parsons, J.G.

2013-01-01

Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4 ± 0.9 nm (Fe3O4) and 15.5 ± 0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ΔG values, and positive ΔH values. The ΔS values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ΔS values for chromium(VI) binding under the light reaction conditions were determined to be negative. PMID:23558081

Fe3O4 and MnO2 assembled on honeycomb briquette cinders (HBC) for arsenic removal from aqueous solutions.

PubMed

Zhu, Jin; Baig, Shams Ali; Sheng, Tiantian; Lou, Zimo; Wang, Zhuoxing; Xu, Xinhua

2015-04-09

In this study, a novel composite adsorbent (HBC-Fe3O4-MnO2) was synthesized by combining honeycomb briquette cinders (HBC) with Fe3O4 and MnO2 through a co-precipitation process. The purpose was to make the best use of the oxidative property of MnO2 and the adsorptive ability of magnetic Fe3O4 for enhanced As(III) and As(V) removal from aqueous solutions. Experimental results showed that the adsorption capacity of As(III) was observed to be much higher than As(V). The maximum adsorption capacity (2.16 mg/g) was achieved for As(III) by using HBC-Fe3O4-MnO2 (3:2) as compared to HBC-Fe3O4-MnO2 (2:1) and HBC-Fe3O4-MnO2 (1:1). The experimental data of As(V) adsorption fitted well with the Langmuir isotherm model, whereas As(III) data was described perfectly by Freundlich model. The pseudo-second-order kinetic model was fitted well for the entire adsorption process of As(III) and As(V) suggesting that the adsorption is a rate-controlling step. Aqueous solution pH was found to greatly affect the adsorption behavior. Furthermore, co-ions including HCO3(-) and PO4(3-) exhibited greater influence on arsenic removal efficiency, whereas Cl(-), NO3(-), SO4(2-) were found to have negligible effects on arsenic removal. Five consecutive adsorption-regeneration cycles confirmed that the adsorbent could be reusable for successive arsenic treatment and can be used in real treatment applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Origin of stratiform sediment-hosted manganese carbonate ore deposits: Examples from Molango, Mexico, and TaoJiang, China

USGS Publications Warehouse

Okita, P.M.; Shanks, Wayne C.

1992-01-01

Carbonate and sulfide minerals from the Molango, Mexico, and TaoJiang, China, Mn deposits display similar and distinctive ??34S and ??13C patterns in intervals of manganese carbonate mineralization. ??13C-values for Mn-bearing carbonate range from -17.8 to +0.5??? (PDB), with the most negative values occurring in high-grade ore zones that are composed predominantly of rhodochrosite. In contrast, calcite from below, within and above Mn-carbonate zones at Molango has ??13C???0??? (PDB). Markedly negative ??13C data indicate that a large proportion of the carbon in Mn-carbonates was derived from organic matter oxidation. Diagenetic reactions using MnO2 and SO2-4 to oxidize sedimentary organic matter were the principle causes of such 12C enrichment. Pyrite content and sulfide ?? 34S-values also show distinctive variations. In unmineralized rocks, very negative ??34S-values (avg. < -21??? CDT) and abundant pyrite content suggest that pyrite formed from diagenetic, bacteriogenic sulfate reduction. In contrast, Mn-bearing horizons typically contain only trace amounts of pyrite (e.g., <0.5 wt% S with ??34S-values 34S-enriched, in some cases to nearly the value for contemporaneous seawater. 34S-enriched pyrite from the Mn-carbonate intervals indicates sulfide precipitation in an environment that underwent extensive SO2-4 reduction, and was largely a closed system with regard to exchange of sulfate and dissolved sulfide with normal seawater. The occasional occurrence of 34S-depleted pyrite within Mn-carbonate zones dominated by 34S-enriched pyrite is evidence that closed-system conditions were intermittent and limited to local pore waters and did not involve entire sedimentary basins. Mn-carbonate precipitation may have occluded porosity in the surficial sediments, thus establishing an effective barrier to SO2-4 exchange with overlying seawater. Similar isotopic and mineralogic characteristics from both the Molango and TaoJiang deposits, widely separated in geologic time and space, suggest they were formed similarly by MnO2 precipitation at the margins of dysaerobic to anoxic marine basins. Mn-carbonate formed predominantly by early-diagenetic reduction of Mn-oxides via oxidation of organic matter in near-surface sediments. In addition to MnCO3 precipitation, organic matter oxidation reactions resulted in oxidation of FeS to Fe-oxides such as magnetite, maghemite and hematite. The latter process explains anomalously low pyrite content and abundant Fe-oxide minerals in ore zones dominated by rhodochrosite. ?? 1992.

Trace elements in starter infant formula: dietary intake and safety assessment.

PubMed

Bargellini, Annalisa; Venturelli, Francesco; Casali, Elisabetta; Ferrari, Angela; Marchesi, Isabella; Borella, Paola

2018-01-01

The aim of this study was to investigate the concentrations of five essential (Fe, Mn, Zn, Cu and Se) and four non-essential/toxic elements (Cr, Cd, Ni and Pb) in 35 different starter infant formulas (0-6 months) sold in Italy. In addition, a safety assessment of these trace elements was carried out, by comparing the estimated daily intake (EDI) with the adequate intake (AI) and the provisional tolerable daily intake (PTDI), with a view to provide information on the metal distribution patterns and health risk to infants arising from the consumption of these products. The concentrations were determined by using inductively coupled plasma mass spectrometry after microwave digestion. The concentrations expressed in geometric mean ± geometric standard deviation of Fe (6.17 ± 1.61 mg/L), Zn (6.21 ± 1.31 mg/L), Cu (416.4 ± 1.21 μg/L), Mn (121.5 ± 1.85 μg/L) and Se (13.27 ± 1.67 μg/L) were within legal limits. In spite of this, the mean EDIs of Fe (4.81 mg/day) and Mn (94.75 μg/day) were many times higher than the recommended AI, especially for Mn. Chromium, Ni, Cd and Pb concentrations were not detectable in 11, 37, 57 and 66% of the samples, respectively. Considering the overall sample, the GM ± GSD of these elements were 4.80 ± 5.35 μg/L for Cr, 1.02 ± 11.65 μg/L for Ni, 0.21 ± 14.83 μg/L for Cd and 0.14 ± 17.13 μg/L for Pb. The mean EDIs were far below the respective PTDI. When the safety assessment was based on the 75° percentile level of each elements, all EDIs remained well below the PTDI, with the exception of Cd, whose EDI approached (74.7%), albeit remaining below the PTDI. In conclusion, our results and the increased awareness on the potential risks of excessive Mn and Fe for infants support that an urgent scientific-based definition of the appropriated levels of fortification in formulas is required. Moreover, regular monitoring of all the stages of production of infant formulas is essential in order to limit toxic metal contamination.

66. Photocopy of photograph (original print in the Minnesota Historical ...

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

66. Photocopy of photograph (original print in the Minnesota Historical Society, St. Paul, Minnesota, ca. 1925. #19657.) VIEW TO NORTHWEST, SHOWING SPAN NOS. 21 TO 26 - Smith Avenue High Bridge, Smith Avenue between Cherokee Avenue & Cliff Street, Saint Paul, Ramsey County, MN

Marine ferromanganese deposits as a source of rare metals for high- and green-tech applications: Comparison with land-based deposits

NASA Astrophysics Data System (ADS)

Hein, J. R.; Conrad, T. A.; Koschinsky, A.

2011-12-01

Marine ferromanganese (Fe-Mn) crusts are strongly enriched relative to the lithosphere in many rare and strategic metals, including Te, Co, Mo, Bi, Pt, W, Zr, Nb, Y, and rare-earth elements (REE). Fe-Mn nodules are strongly enriched in Ni, Cu, Co, Mo, Zr, Li, and REY. Relative to Fe-Mn crusts, nodules are more enriched in Ni, Cu, and Li, with subequal amounts of Mo. The metals are sorbed from seawater onto the Fe and Mn phases, and also from sediment pore waters for nodules. An electrochemical model describes a first-order process for acquisition of metals from seawater, with positively charged ions sorbed onto the negative charged surface of MnO2 and negatively charged and neutral ions in seawater sorbed on the slightly positive charged FeO(OH) surface. Second-order processes include surface oxidation (e.g., Co, Pt, Te, Ce, Tl), substitution, and precipitation of discrete phases. The metals most enriched in these marine deposits are essential for a wide variety of high- and green-tech applications. Over the past few years, the global market for many of them has been supplied from one or two major sources. Because of increased competition for resources from rapidly expanding economies (i.e. China, India, Brazil), supplies may not meet demands. Deep-ocean deposits may offer a partial solution to these projected shortages, but marine deposits have not been compared in terms of grade and tonnage with land-based deposits. Here we compare data for the Clarion-Clipperton Fe-Mn Nodule Zone (CCZ) in the NE Pacific and the central Pacific Fe-Mn crust zone (PCZ) with the global land-based reserves. Nodules in the CCZ have 1.1 times more Mn, 1.4 times more Te, 1.85 times more Ni, 3.2 times more Co, and 4 times more Y than the entire global land-based reserves for those metals. Metals in CCZ nodules as a percent of the total global land-based reserves are Cu 22%, Mo 63%, W 21%, Li 19%, Nb 13%, and REE 11%. Fe-Mn crusts in the PCZ have 3.8 times more Co, 3.5 times more Y, and an incredible 9 times more Te than the entire land-based reserves. Metals in PCZ crusts as a percent of the total global land-based reserves are Bi 47%, REO 13%, Nb 13%, and W 11%. CCZ nodules and PCZ crusts are compared with the two largest existing land-based REE mines, Mountain Pass (MP) in USA and Bayan Obo (Obo) in China. The land-based deposits are higher grade but lower tonnage (MP 0.3x108 tons at 7.5% total REEs as oxides (TREO); Obo, 0.5x108 tons at 6% TREO), compared to the CCZ (211x108 tons at 0.10% TREO) and PCZ (75.3x108 tons at 0.3% TREO). These grades and tonnages correspond to tons of TREO of 4.7x107 Obo, 2.6x106 MP; 2.1x107 CCZ, and 2.1x107 PCZ. Both land-based deposits have <1% heavy REE, whereas the CCZ has 10% HREE and the PCZ, 6.3% HREE, typical of crusts elsewhere in the global ocean. An important environmental issue is high Th contents in the land-based deposits (100s of ppm); in contrast to low Th in marine deposits (mean 14 ppm CCZ; 11 ppm PCZ). Rare metals in the marine deposits would likely be recovered as byproducts of Ni, Cu, and Co mining, with the possible exception of Te.

Temperature dependence of quantized states in strained-layer In0.21Ga0.79As/GaAs single quantum well

NASA Astrophysics Data System (ADS)

Chi, Wuh-Sheng; Huang, Ying-Sheng; Qiang, Hao; Pollak, Fred H.; Pettit, David G.; Woodall, Jerry M.

1994-02-01

The piezoreflectance (PzR) and photoreflectance (PR) measurements of a strained-layer (001) In0.21Ga0.79As/GaAs single quantum well as a function of temperature in the range of 20 to 300 K have been carried out. A careful analysis of the PzR and PR spectra has led to the identification of various excitonic transitions, mnH(L), between the mth conduction band state to the nth heavy (light)-hole band state. The parameters that describe the temperature dependence of E(sub mnH(L)) are evaluated. The detailed study of the temperature variation of excitonic transition energies indicates that the main influence of temperature on quantized transitions is through the temperature dependence of the band gap of the constituent material in the well. The temperature dependence of the linewidth of the 11H exciton is evaluated and compared with that of the bulk material.

Temperature Dependence of Quantized States in Strained-Layer In0.21Ga0.79As/GaAs Single Quantum Well

NASA Astrophysics Data System (ADS)

Chi, Wuh-Sheng; Huang, Ying-Sheng; Qiang, Hao; Pollak, Fred; Pettit, David; Woodall, Jerry

1994-02-01

The piezoreflectance (PzR) and photoreflectance (PR) measurements of a strained-layer (001) In0.21Ga0.79As/GaAs single quantum well as a function of temperature in the range of 20 to 300 K have been carried out. A careful analysis of the PzR and PR spectra has led to the identification of various excitonic transitions, mnH(L), between the mth conduction band state to the nth heavy (light)-hole band state. The parameters that describe the temperature dependence of E mnH(L) are evaluated. The detailed study of the temperature variation of excitonic transition energies indicates that the main influence of temperature on quantized transitions is through the temperature dependence of the band gap of the constituent material in the well. The temperature dependence of the linewidth of the 11H exciton is evaluated and compared with that of the bulk material.

Diaqua­bis{5-carboxy-2-[(1H-1,2,4-triazol-1-yl)­meth­yl]-1H-imidazole-4-carboxyl­ato}­manganese(II)

PubMed Central

Ding, De-Gang; Tong, Yan

2010-01-01

In the title compound, [Mn(C8H6N5O4)2(H2O)2], the MnII ion is situated on an inversion center and is six-coordinated by two N and two O atoms from two L ligands (HL = 2-[(1H-1,2,4-triazol-1-yl)meth­yl]-1H-imidazole-4,5-dicarboxylic acid) and two water mol­ecules in a distorted octa­hedral geometry. In ligand L, the imidazole and triazole rings form a dihedral angle of 74.25 (8)°. Mol­ecules are assembled into a three-dimensional structure via inter­molecular O—H⋯O, O—H⋯N and N—H⋯N hydrogen-bonds, and π–π inter­actions with a short distance of 3.665 (2) Å between the centroids of the imidazole and triazole rings of neighbouring mol­ecules. PMID:21579014

Level of heavy metals in some edible and poisonous macrofungi from Batman of South East Anatolia, Turkey.

PubMed

Yesil, Omer Faruk; Yildiz, Abdunnasir; Yavuz, Omer

2004-07-01

The macrofungi specimens were collected and identified from locations around Batman province of Turkey. A group of 21 macrofungi were collected from 29 different locations and analysed for the heavy metal contents. The highest Pb and Cu levels were found in Russula rubroalba while the highest Cd level was determined for the species Agaricus xanthodermus. Fe level was maximum for the species Funalia trogii; Mn for Mycena personsii; Zn level was for Morchella esculenta and Co level was for the species Agaricus xanthodermus. The lowest Cd, Cu, Mn and Zn contents were found in Inotus hispidus.

Comparison of Explosives Residues from the Blow-in-Place Detonation of 155-mm High-Explosive Projectiles

DTIC Science & Technology

2006-06-01

were M107 high-explosive deep-cavity 155-mm howitzer projectiles with a supplemental charge and an M739 point- detonating fuze mounted in the nose...M107, HE, w/o fuze IOP03E100-011 14 1390010809447 N340 Fuze, point-detonating, M739 MA-84B007-013 14 1375014151232 ML47 Cap, blasting, non-electric 30... M739 N340 0 21 0 ə Cap, blasting, M11 ML47 ə 27 ə ə Cap, blasting, M13 MN03 0 ə 0 ə Cap, blasting, M14 MN06 0 0 0 ə Cord, detonating M456 0

The role of marine biotoxins on the trophic transfer of Mn and Zn in fish.

PubMed

Pouil, Simon; Clausing, Rachel J; Metian, Marc; Bustamante, Paco; Dechraoui Bottein, Marie-Yasmine

2018-05-01

Essential nutrients are critical for physiological processes of organisms. In fish, they are obtained primarily from the diet, and their transfer and accumulation are known to be impacted by environmental variables such as water temperature, pH and salinity, as well as by diet composition and matrices. Yet, prey items consumed by fish may also contain toxic compounds such as marine toxins associated with harmful algae. These biotoxins have the potential to affect essential trace element assimilation in fish through chemical interactions such as the formation of trace element-toxin complexes or by affecting general fish physiology as in the modification of ion-specific transport pathways. We assessed the influence of dietary exposure to brevetoxins (PbTxs), ichthyotoxic neurotoxins produced by the dinoflagellate Karenia brevis, on trophic transfer of two essential trace elements, Mn and Zn, in a fish model. Using ecologically relevant concentrations of PbTxs and trace elements in controlled laboratory conditions, juvenile turbots Scophthalmus maximus were given food containing PbTxs before or at the same time as a feeding with radiotracers of the chosen essential elements ( 54 Mn and 65 Zn). Treatments included simultaneous exposure (PbTxs +  54 Mn +  65 Zn) in a single-feeding, 3-week daily pre-exposure to dietary PbTx followed by a single feeding with 54 Mn and 65 Zn, and a control ( 54 Mn and 65 Zn only). After a 21-day depuration period, turbot tissue brevetoxin levels were quantified and assimilation efficiencies of 54 Mn and 65 Zn were assessed. PbTxs were found in turbot tissues in each exposure treatment, demonstrating dietary trophic transfer of these toxins; yet, no differences in assimilation efficiencies of Mn or Zn were found between treatments or the control (p > 0.05). These results indicate that, in our experimental conditions, PbTx exposure does not significantly affect the trophic transfer of Mn and Zn in fish. Copyright © 2018 Elsevier B.V. All rights reserved.

Remote-loading of liposomes with manganese-52 and in vivo evaluation of the stabilities of 52Mn-DOTA and 64Cu-DOTA using radiolabelled liposomes and PET imaging.

PubMed

Jensen, Andreas I; Severin, Gregory W; Hansen, Anders E; Fliedner, Frederikke P; Eliasen, Rasmus; Parhamifar, Ladan; Kjær, Andreas; Andresen, Thomas L; Henriksen, Jonas R

2018-01-10

Liposomes are nanoparticles used in drug delivery that distribute over several days in humans and larger animals. Radiolabeling with long-lived positron emission tomography (PET) radionuclides, such as manganese-52 ( 52 Mn, T½=5.6days), allow the imaging of this biodistribution. We report optimized protocols for radiolabeling liposomes with 52 Mn, through both remote-loading and surface labeling. For comparison, liposomes were also remote-loaded and surface labeled with copper-64 ( 64 Cu, T½=12.7h) through conventional means. The chelator DOTA was used in all cases. The in vivo stability of radiometal chelates is widely debated but studies that mimic a realistic in vivo setting are lacking. Therefore, we employed these four radiolabeled liposome types as platforms to demonstrate a new concept for such in vivo evaluation, here of the chelates 52 Mn-DOTA and 64 Cu-DOTA. This was done by comparing "shielded" remote-loaded with "exposed" surface labeled variants in a CT26 tumor-bearing mouse model. Remote loading (90min at 55°C) and surface labeling (55°C for 2h) of 52 Mn gave excellent radiolabeling efficiencies of 97-100% and 98-100% respectively, and the liposome biodistribution was imaged by PET for up to 8days. Liposomes with surface-conjugated 52 Mn-DOTA exhibited a significantly shorter plasma half-life (T ½ =14.4h) when compared to the remote-loaded counterpart (T ½ =21.3h), whereas surface-conjugated 64 Cu-DOTA cleared only slightly faster and non-significantly, when compared to remote-loaded (17.2±2.9h versus 20.3±1.2h). From our data, we conclude the successful remote-loading of liposomes with 52 Mn, and furthermore that 52 Mn-DOTA may be unstable in vivo whereas 64 Cu-DOTA appears suitable for quantitative imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxidation of dimethylselenide by δMnO2: oxidation product and factors affecting oxidation rate

USGS Publications Warehouse

Wang, Bronwen; Burau, Richard G.

1995-01-01

Volatile dimethylselenide (DMSe) was transformed to a nonvolatile Se compound in a ??-MnO2 suspension. The nonvolatile product was a single compound identified as dimethylselenoxide based on its mass spectra pattern. After 24 h, 100% of the DMSe added to a ??-MnO2 suspension was converted to nonpurgable Se as opposed to 20%, 18%, and 4% conversion for chromate, permanganate, and the filtrate from the suspension, respectively. Manganese was found in solution after reaction. These results imply that the reaction between manganese oxide and DMSe was a heterogeneous redox reaction involving solid phase ??-MnO2 and solution phase DMSe. Oxidation of DMSe to dimethylselenoxide [OSe(CH3)2] by a ??-MnO2 suspension appears to be first order with respect to ??-MnO2, to DMSe, and to hydrogen ion with an overall rate law of d[OSe(CH3)2 ]/dt = 95 M-2 min-1 [MnO2]1[DMSe]1[H+]1 for the MnO2 concentration range of 0.89 ?? 10-3 - 2.46 ?? 10-3 M, the DMSe concentration range of 3.9 ?? 10-7 - 15.5 ?? 10-7 M Se, and a hydrogen ion concentation range of 7.4 ?? 10-6 -9.5 ?? 10-8 M. A general surface site adsorption model is consistent with this rate equation if the uncharged |OMnOH is the surface adsorption site. DMSe acts as a Lewis base, and the manganese oxide surface acts as a Lewis acid. DMSe adsorption to |OMnOH can be viewed as a Lewis acid/ base complex between the largely p orbitals of the DMSe lone pair and the unoccupied eg orbitals on manganese oxide. For such a complex, frontier molecular orbital theory predicts electron transfer to occur via an inner-sphere complex between the DMSe and the manganese oxide. ?? 1995 American Chemical Society.

Isolation, Chromosomal Localization, and Differential Expression of Mitochondrial Manganese Superoxide Dismutase and Chloroplastic Copper/Zinc Superoxide Dismutase Genes in Wheat1

PubMed Central

Wu, Guohai; Wilen, Ronald W.; Robertson, Albert J.; Gusta, Lawrence V.

1999-01-01

Superoxide dismutase (SOD) gene expression was investigated to elucidate its role in drought and freezing tolerance in spring and winter wheat (Triticum aestivum). cDNAs encoding chloroplastic Cu/ZnSODs and mitochondrial MnSODs were isolated from wheat. MnSOD and Cu/ZnSOD genes were mapped to the long arms of the homologous group-2 and -7 chromosomes, respectively. Northern blots indicated that MnSOD genes were drought inducible and decreased after rehydration. In contrast, Cu/ZnSOD mRNA was not drought inducible but increased after rehydration. In both spring and winter wheat seedlings exposed to 2°C, MnSOD transcripts attained maximum levels between 7 and 49 d. Transcripts of Cu/ZnSOD mRNA were detected sooner in winter than in spring wheat; however, they disappeared after 21 d of acclimation. Transcripts of both classes of SOD genes increased during natural acclimation in both spring and winter types. Exposure of fully hardened plants to three nonlethal freeze-thaw cycles resulted in Cu/Zn mRNA accumulation; however, MnSOD mRNA levels declined in spring wheat but remained unchanged in winter wheat. The results of the dehydration and freeze-thaw-cycle experiments suggest that winter wheat has evolved a more effective stress-repair mechanism than spring wheat. PMID:10364402

Enhancement of the Co magnetic moment in bcc Co1-xMnx on MgO

NASA Astrophysics Data System (ADS)

Snow, Ryan; Bhatkar, Harsh; N'diaye, Alpha; Arenholz, Elke; Idzerda, Yves; Montana State University Team; Lawrence Berkeley National Laboratries Team

Using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (MCD), we show that the elemental Co moment for MBE grown thin films of bcc Co1-xMnx grown on MgO(001) is enhanced by 40% to a maximum value of 2.1 μB at x =0.24. The net Mn moment is found to align parallel with Co for all concentrations and remains roughly constant until x =0.3, then drops steadily, up to x =0.7, where the total moment of the film abruptly collapses to zero. Using a low-concentration Mn moment of 3.0 μB, the average magnetization lies directly on the Slater-Pauling (SP) curve for concentrations up to about x =.25, where it reaches a maximum moment of 2.3 μB /atom. This peak is slightly shifted and the slope is steeper on the high-Mn concentration side of the peak relative to the standard SP curve. This is in stark contrast to the fcc CoMn and hcp CoCr bulk behavior which shows only a rapid total moment reduction with Mn concentration. This material is based upon work supported by the National Science Foundation under Grant ECCS-1542210. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Con.

Synthesis and electrochemical properties of Li2/3Ni1/3Mn2/3O2 as a novel 5 V class positive electrode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Chiba, Kazuki; Shikano, Masahiro; Sakaebe, Hikari

2016-02-01

A lithium nickel manganese oxide, O3-Li2/3Ni1/3Mn2/3O2, is synthesized from the precursor, P3-Na2/3Ni1/3Mn2/3O2, by a Na+/Li+ ion exchange reaction using molten salt. Post-heating at 300, 400, 500, 600, and 700 °C is carried out for 5 h in air. The products are characterized by powder XRD, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), SEM, 6Li-magic-angle-spinning-NMR, and electrochemical measurements. The charge/discharge profiles of O3-Li2/3Ni1/3Mn2/3O2, thermally treated at 500 °C, show a high-potential plateau region at 4.8 V. Furthermore, sloping voltage profiles are observed at an average voltage of 3.21 V. An initial discharge capacity of 257 mA h g-1 is obtained between 2.0 and 4.8 V with a current density of 15 mA g-1 at 25 °C. This capacity corresponds to 0.90 electron transfers per formula unit. This study shows that Post-heating of O3-Li2/3Ni1/3Mn2/3O2 is effective to improve its electrochemical properties.

High voltage stable liquid electrolytes for Li 1+ xMn 2O 4/carbon rocking-chair lithium batteries

NASA Astrophysics Data System (ADS)

Guyomard, D.; Tarascon, J. M.

A high voltage oxidation-resistant electrolyte is required for Li 1+ xMn 2O 4/carbon rocking-chair cells that need to be charged up to a voltage higher than 4.3 V. Many electrolyte compositions have been tested for their ability to resist to high voltages on Li 1+ xMn 2O 4 electrodes and their ability to maintain high ionic conductivity in a wide temperature range. This survey allowed us to select new electrolyte compositions in the system dimethyl carbonate (DMC) + ethylene carbonate (EC) + lithium hexafluorophosphate (LiPF 6) that are kinetically stable up to almost 5 V versus lithium at 55 °C on Li 1+ xMn 2O 4 electrodes. Low rate potentiostatic experiments, coupled with coulombmetric measurements in the 4.25-5.1 V range, allowed to select the following compositions: (DMC + EC) (1:2) + 1 M LiPF 6 and (DMC + EC) (2:1) + 1.5 M LiPF 6 as the best. These compositions have been used in practical Li 1+ xMn 2O 4/carbon rocking-chair batteries and show better performance in terms of cycle life and self-discharge over a wider temperature range. They are compatible with rocking-chair batteries based on LiCoO 2 and LiNiO 2 as well.

Outstanding laser damage threshold in Li2MnGeS4 and tunable optical nonlinearity in diamond-like semiconductors.

PubMed

Brant, Jacilynn A; Clark, Daniel J; Kim, Yong Soo; Jang, Joon I; Weiland, Ashley; Aitken, Jennifer A

2015-03-16

The new Li2MnGeS4 and Li2CoSnS4 compounds result from employing a rational and simple design strategy that guides the discovery of diamond-like semiconductors (DLSs) with wide regions of optical transparency, high laser damage threshold, and efficient second-order optical nonlinearity. Single-crystal X-ray diffraction was used to solve and refine the crystal structures of Li2MnGeS4 and Li2CoSnS4, which crystallize in the noncentrosymmetric space groups Pna21 and Pn, respectively. Synchrotron X-ray powder diffraction (SXRPD) was used to assess the phase purity, and diffuse reflectance UV-vis-NIR spectroscopy was used to estimate the bandgaps of Li2MnGeS4 (Eg = 3.069(3) eV) and Li2CoSnS4 (Eg = 2.421(3) eV). In comparison with Li2FeGeS4, Li2FeSnS4, and Li2CoSnS4 DLSs, Li2MnGeS4 exhibits the widest region of optical transparency (0.60-25 μm) and phase matchability (≥1.6 μm). All four of the DLSs exhibit second-harmonic generation and are compared with the benchmark NLO material, AgGaSe2. Most remarkably, Li2MnGeS4 does not undergo two- or three-photon absorption upon exposure to a fundamental Nd:YAG beam (λ = 1.064 μm) and exhibits a laser damage threshold > 16 GW/cm(2).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yue Ru; Poyraz, Altug S.; Hu, Xiaobing

Birnessite type layered manganese dioxides (δ-MnO 2) have attracted considerable attention in recent years as 2D intercalation cathodes for rechargeable Li +, Na +, and Mg 2+ batteries due to fast ion diffusion through their negatively charged δ-MnO 2 sheets separated by interlayer cations and a stable Mn 3+/4+ redox couple. Here we report the preparation and electrochemistry of zero and divalent copper co-intercalated birnessite type manganese dioxide (Cu 0 0.03Cu 2+ 0.21Na 0.12MnO 2·0.9H 2O). The copper intercalated birnessite materials were fully characterized utilizing powder X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM).more » The mixed valent nature of intercalated Cu 0 and Cu 2+ was confirmed by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). Electrochemical evaluation results show that zero valent copper intercalated birnessite exhibits higher discharge capability, improved cyclability, and lower impedance compared to the Cu 2+ only intercalated (Cu 0.26MnO 2·1.0H 2O) and Cu free Na birnessite (Na 0.40MnO 2·1.0H 2O) materials. Remarkably, zero valent copper birnessite shows almost no fade after 10 cycles at 0.1 mV/s. Electrochemical impedance spectroscopy results suggest that charge transfer resistivity of Cu 0 modified samples was much lower than that of Cu 2+ and Cu free birnessite, indicating that the presence of a small amount of Cu 0 improves the conductivity of birnessite and results in better electrochemical cyclability, rate capability, and lower impedance.« less

Effective Treatment of Manganese-Induced Occupational Parkinsonism With p-Aminosalicylic Acid: A Case of 17-Year Follow-Up Study

PubMed Central

Jiang, Yue-Ming; Mo, Xue-An; Du, Feng-Qi; Fu, Xue; Zhu, Xia-Yan; Gao, Hong-Yu; Xie, Jin-Lan; Liao, Feng-Ling; Pira, Enrico; Zheng, Wei

2014-01-01

Objective Chronic manganese (Mn) intoxication induces syndromes resembling Parkinson disease. The clinical intervention has largely been unsuccessful. We report a 17-year follow-up study of effective treatment of occupational Mn parkinsonism with sodium para-aminosalicylic acid (PAS). Methods The patient, female and aged 50 at the time of treatment, was exposed to airborne Mn for 21 years (1963–1984). The patient had palpitations, hand tremor, lower limb myalgia, hypermyotonia, and a distinct festinating gait. She received 6 g PAS per day through an intravenous drip infusion for 4 days and rested for 3 days as one therapeutic course. Fifteen such courses were carried out between March and June 1987. Results At the end of PAS treatment, her symptoms were significantly alleviated, and handwriting recovered to normal. Recent follow-up examination at age 67 years (in 2004) showed a general normal presentation in clinical, neurologic, brain magnetic resonance imaging, and handwriting examinations with a minor yet passable gait. Conclusions This case study suggests that PAS appears to be an effective drug for treatment of severe chronic Mn poisoning with a promising prognosis. PMID:16766929

Magnetically separable Prussian blue analogue Mn₃[Co(CN)₆]₂·nH₂O porous nanocubes as excellent absorbents for heavy metal ions.

PubMed

Hu, Lin; Mei, Ji-Yang; Chen, Qian-Wang; Zhang, Ping; Yan, Nan

2011-10-05

The application of Prussian blue analogue (PBA) Mn(3)[Co(CN)(6)](2)·nH(2)O porous nanocubes as absorbents for heavy metal ions has been demonstrated. The result indicates that Mn(3)[Co(CN)(6)](2)·nH(2)O porous nanocubes with average diameter of 240 nm possess excellent adsorption efficiency for Pb(2+) ions (94.21% at initial Pb(2+) concentration of 10 mg L(-1)). Moreover, Mn(3)[Co(CN)(6)](2)·nH(2)O porous nanocubes can also show high adsorption efficiency on heavy metal ions even in a strong acidic solution due to its chemical stability. Notably, an external magnet could be used to accelerate the separation of Mn(3)[Co(CN)(6)](2)·nH(2)O from the treated solution. It is suggested that the high adsorption efficiency may derive from the large surface area, M(3)(II)[M(III)(CN)(6)](2)·nH(2)O porous framework structure and affinity between polarizable π-electron clouds of the cyanide bridges and heavy metals ions.

The structure and ordering of ɛ-MnO 2

NASA Astrophysics Data System (ADS)

Kim, Chang-Hoon; Akase, Zentaro; Zhang, Lichun; Heuer, Arthur H.; Newman, Aron E.; Hughes, Paula J.

2006-03-01

The presence of ɛ-MnO 2 as a major component of electrolytic manganese dioxide (EMD) has been demonstrated by a combined X-ray diffraction/transmission electron microscopy (TEM) study. ɛ-MnO 2 usually has a partially ordered defect NiAs structure containing 50% cation vacancies; these vacancies can be fully ordered by a low temperature (200 °C) heat treatment to form a pseudohexagonal but monoclinic superlattice. Numerous fine-scale anti-phase domain boundaries are present in ordered ɛ-MnO 2 and cause extensive peak broadening and a massive shift of a very intense, 0.37 nm superlattice peak. This suggests a radically different explanation of the ubiquitous, very broad ˜0.42 nm peak (˜21-22° 2 θ, Cu Kα radiation) in EMDs, which heretofore has been attributed to Ramsdellite containing numerous planar defects. This work confirms the multi-phase model of equiaxed EMDs proposed by Heuer et al. [ITE Lett. 1(6) (2000) B50; Proc. Seventh Int. Symp. Adv. Phys. Fields 92 (2001)], rather than the defective single-phase model of Chabre and Pannetier [Prog. Solid State Chem. 23 (1995) 1] and Bowden et al. [ITE Lett. 4(1) (2003) B1].

On the novel double perovskites A2Fe(Mn0.5W0.5)O6 (A= Ca, Sr, Ba). Structural evolution and magnetism from neutron diffraction data

NASA Astrophysics Data System (ADS)

García-Ramos, Crisanto A.; Larrégola, Sebastián; Retuerto, María; Fernández-Díaz, María Teresa; Krezhov, Kiril; Alonso, José Antonio

2018-06-01

New A2Fe(Mn0.5W0.5)O6 (A = Ca, Sr, Ba) double perovskite oxides have been prepared by ceramic techniques. X-ray diffraction (XRD) complemented with neutron powder diffraction (NPD) indicate a structural evolution from monoclinic (space group P21/n) for A = Ca to cubic (Fm-3m) for A = Sr and finally to hexagonal (P63/mmc) for A = Ba as the perovskite tolerance factor increases with the A2+ ionic size. The three oxides present different tilting schemes of the FeO6 and (Mn,W)O6 octahedra. NPD data also show evidence in all cases of a considerable anti-site disordering, involving the partial occupancy of Fe positions by Mn atoms, and vice-versa. Magnetic susceptibility data show magnetic transitions below 50 K characterized by a strong irreversibility between ZFC and FC susceptibility curves. The A = Ca perovskite shows a G-type magnetic structure, with weak ordered magnetic moments due to the mentioned antisite disordering. Interesting magnetostrictive effects are observed for the Sr perovskite below 10 K.

Relationship between blood manganese levels and children's attention, cognition, behavior, and academic performance--a nationwide cross-sectional study.

PubMed

Bhang, Soo-Young; Cho, Soo-Churl; Kim, Jae-Won; Hong, Yun-Chul; Shin, Min-Sup; Yoo, Hee Jeong; Cho, In Hee; Kim, Yeni; Kim, Bung-Nyun

2013-10-01

Manganese (Mn) is neurotoxic at high concentrations. However, Mn is an essential element that can protect against oxidative damage; thus, extremely low levels of Mn might be harmful. Our aim was to examine whether either high or low environmental Mn exposure is related to academic and attention function development among school-aged children. This cross-sectional study included 1089 children 8-11 years of age living in five representative areas in South Korea. Blood Mn, blood lead, and urine cotinine were measured. We assessed IQ with the Wechsler Abbreviated Scale of Intelligence; attention with a computerized continuous performance test called the Attention-deficit/hyperactivity disorder (ADHD) Diagnostic System (ADS), the Korean version of the Stroop Color-Word Test, the Children's Color Trails Test (CCTT), and the ADHD Rating Scale; academic functions with the Learning Disability Evaluation Scale (LDES); and emotional and behavioral problems with the Korean version of the Child Behavior Checklist (CBCL). We further assessed the presence of ADHD using a highly structured diagnostic interview, the Diagnostic Interview Schedule for Children Version IV (DISC-IV). The median blood concentration of Mn was 14.14 µg/L. We observed a nonlinear association between the CCTT2 completion time and the CPT commission error (F=3.14, p=0.03 and F=4.05, p=0.01, respectively). We divided the data into three groups: lower (<8.154 µg/L), and upper 5th percentile (>21.453 µg/L) and middle 90th percentile to determine whether a lack or overload of Mn could cause adverse effects. After adjusting for urine cotinine, blood lead, children's IQ, and other potential confounders, the high Mn group showed lower scores in thinking (B=-0.83, p=0.006), reading (B=-0.93, p=0.004), calculations (B=-0.72, p=0.005), and LQ (B=-4.06, p=0.006) in the LDES and a higher commission error in the CPT (B=8.02, p=0.048). The low Mn group showed lower color scores in the Stroop test (B=-3.24, p=0.040). We found that excess Mn in children is associated with lower scores of thinking, reading, calculation, and LQ in the LDES and higher scores of commission error in the ADS test. In contrast, lower Mn in children is associated with lower color scores in the Stroop test. The findings of this cross-sectional study suggest that excess exposure or deficiency of Mn can cause harmful effects in children. Copyright © 2013 Elsevier Inc. All rights reserved.

Syntheses, structures, and properties of trinuclear complexes [M(bpca)(2)(M'(hfac)(2))(2)], constructed with the complexed bridging ligand [M(bpca)(2)] [M, M' = Ni(II), Mn(II); Cu(II), Mn(II); Fe(II), Mn(II); Ni(II), Fe(II); and Fe(II), Fe(II); Hbpca = Bis(2-pyridylcarbonyl)amine, Hhfac = Hexafluoroacetylacetone].

PubMed

Kamiyama, Asako; Noguchi, Tomoko; Kajiwara, Takashi; Ito, Tasuku

2002-02-11

Five trinuclear complexes [M(bpca)(2)(M'(hfac)(2))(2)] (where MM'(2) = NiMn(2), CuMn(2), FeMn(2), NiFe(2), and FeFe(2); Hbpca = bis(2-pyridylcarbonyl)amine; and Hhfac = hexafluoroacetylacetone) were synthesized almost quantitatively by the reaction of [M(bpca)(2)] and [M'(hfac)(2)] in 1:2 molar ratio, and their structures and magnetic properties were investigated. Three complexes, with M' = Mn, crystallize in the same space group, Pna2(1), whereas two complexes, with M' = Fe, crystallize in P4(1), and complexes within each set are isostructural to one another. In all complexes, [M(bpca)(2)] acts as a bis-bidentate bridging ligand to form a linear trinuclear complex in which three metal ions are arranged in the manner M'-M-M'. The central metal ion is in a strong ligand field created by the N(6) donor set, and hence the Fe(II) in the [Fe(bpca)(2)] moiety is in a low-spin state. The terminal metal ions (M') are surrounded by O(6) donor sets with a moderate ligand field, which leads to the high-spin configuration of Fe(II). Three metal ions in all complexes are almost collinear, and metal-metal distances are ca. 5.5 A. The magnetic behavior of NiMn(2) and NiFe(2) shows a weak ferromagnetic interaction between the central Ni(II) ion and the terminal Mn(II) or Fe(II) ions. In these complexes, sigma-spin orbitals of the central Ni(II) ion and those of terminal metal ions have different symmetry about a 2-fold rotation axis through the Ni-N(amide)-M'(terminal) atoms, and this results in orthogonality between the neighboring sigma-spin orbitals and thus ferromagnetic interactions.

A global portrait of the manganese industry-A socioeconomic perspective.

PubMed

Clarke, Carl; Upson, Sophie

2017-01-01

In 2013/14, Risk & Policy Analysts Ltd undertook the first global study on the socio-economic value of Manganese (Mn). Based on a top-down analysis of the key supply chains for Mn, it outlined the economic importance of Mn ore and alloys in terms of their direct and indirect economic value, as well as their effects on employment (jobs and wages). In 2013, global production of Mn ore was worth an estimated US$ 10.2-11.1 billion. Taking into account multiplier effects in the supply chain, the total economic value of Mn ore production globally in 2013 is estimated at US$ 21-23 billion. Direct employment related to Mn ore production is estimated at 44,000-78,000 people worldwide (with total wages estimated at US$ 2.7-4.6 billion per year), plus 33,000-59,000 jobs are created through indirect and induced employment effects. Meanwhile, the production of Mn alloy contributes around US$ 23 billion per year to the global economy (based on global production of around 19 million mt and 2013 market prices). In total, the value of Mn alloy production worldwide, taking into account downstream multiplier effects in the supply chain, is estimated at around US$ 146 billion per year. Direct employment related to Mn alloy production is estimated at 67,000-86,000 jobs worldwide (with total wages estimated at US$ 613-796 million per year), plus 217,000-278,000 jobs created through indirect & induced employment effects. In addition, numerous industries/sectors, products and/or applications are heavily dependent on Mn production and use. Mn is a critical raw material input and alloying element for the steel industry, for which there are no known alternatives. It can be argued that without Mn the entire steel industry (based on the current physico-chemical properties of steel) would not exist and, as a result, the value of the steel industry - an estimated US$ 964 billion to US$ 1446 billion in 2013 - is reliant on the continued supply and use of Mn. Besides its use in steel, Mn is also a critical element in the manufacture of dry cell and other batteries (notably, those used in electric vehicles) and the production of aluminium alloys (e.g. for beverage cans). Mn is also a micronutrient needed for plant growth and plays a vital role in agricultural production. It is also essential for maintaining the health and well-being of the human body and is used in food supplements and medicines. Furthermore, its use in developing applications (such as advanced steel products in automotive applications and batteries for electric vehicles) has the potential to provide socio-economic and environmental benefits in the future through enhancing vehicle safety and reducing fuel use/emissions. Copyright © 2016 Elsevier B.V. All rights reserved.

76 FR 5834 - Notice of Determinations Regarding Eligibility to Apply for Worker Adjustment Assistance

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-02

... domestic industry in an investigation resulting in-- (A) An affirmative determination of serious injury or..., Manpower. 74,428 MH Technologies, LLC......... Mt. Holly Springs, PA... May 19, 2009. 74,565 Smead... Time Insurance Company, Plymouth, MN......... September 21, 2009. DBA Assurant Health, Manpower. 74,654...

Exposure to lambda-cyhalothrin, a synthetic pyrethroid, increases reactive oxygen species production and induces genotoxicity in rat peripheral blood.

PubMed

Fetoui, Hamadi; Feki, Ameni; Salah, Ghada Ben; Kamoun, Hassen; Fakhfakh, Feiza; Gdoura, Radhouane

2015-05-01

Lambda-cyhalothrin (LTC) is a synthetic pyrethroid with a broad spectrum of insecticidal and acaricidal activities used to control a wide range of insect pests in a variety of applications. However, there is little known about its adverse effects, in particular those related to its genotoxicity in humans. To elucidate the genotoxicity mechanisms of LTC, the micronuclei (MN) frequencies, the levels of reactive oxygen species (ROS), erythrocyte osmotic fragility, nitrite (NO) formation, protein carbonyl (PCO) levels and malondialdehyde (MDA) production were evaluated for a period of 7, 14 and 21 days. Our results show that exposure rat to LTC (1/10DL50 = 6.23 mg/kg) for a period of 7, 14 and 21 days induced a noticeable genotoxic effect in rat peripheral blood evidenced by a significant increase in the frequency of MN only at day 21 of treatment. Significant differences between the two groups were observed in erythrocyte osmotic fragility. Further, a significant (p < 0.01) increase in ROS contents, NO formation, PCO levels and lipid peroxidation in erythrocytes were observed at different times of treatments, suggesting the implication of oxidative stress in its toxicity. These results confirm the genotoxic and the pro-oxidant effects of LTC in rat peripheral blood. © The Author(s) 2013.

Enhanced Predictive Handover for Fast Proxy Mobile IPv6

NASA Astrophysics Data System (ADS)

Jeon, Seil; Kang, Namhi; Kim, Younghan

Proxy Mobile IPv6 (PMIPv6) has been proposed in order to overcome the limitations of host-based mobility management in IPv6 networks. However, packet losses during doing handover are still a problem. To solve this issue, several schemes have been developed, and can be classified into two approaches: predictive and reactive handover. Both approaches commonly use bi-directional tunnel between mobile access gateways (MAGs). In predictive schemes especially, mobility support for a mobile node (MN) is triggered by simplified link signal strength. Thereafter, the MN sends handover notification to its serving MAG, and is then able to initiate packet forwarding. Therefore, if the MN moves toward an unexpected MAG that does not have any pre-established tunnel with the serving MAG, it may lead to packet losses. In this paper, we define this problem as Early Packet Forwarding (EPF). As a solution, we propose an enhanced PMIPv6 scheme using two-phase tunnel control based on the IEEE 802.21 Media Independent Handover (MIH).

AMOchar: Amorphous manganese oxide coating of biochar improves its efficiency at removing metal(loid)s from aqueous solutions.

PubMed

Trakal, Lukáš; Michálková, Zuzana; Beesley, Luke; Vítková, Martina; Ouředníček, Petr; Barceló, Andreu Piqueras; Ettler, Vojtěch; Číhalová, Sylva; Komárek, Michael

2018-06-01

A novel sorbent made from biochar modified with an amorphous Mn oxide (AMOchar) was compared with pure biochar, pure AMO, AMO+biochar mixtures and biochar+birnessite composite for the removal of various metal(loid)s from aqueous solutions using adsorption and solid-state analyses. In comparison with the pristine biochar, both Mn oxide-biochar composites were able to remove significantly greater quantities of various metal(loid)s from the aqueous solutions, especially at a ratio 2:1 (AMO:biochar). The AMOchar proved most efficient, removing almost 99, 91 and 51% of Pb, As and Cd, respectively. Additionally, AMOchar and AMO+biochar mixture exhibited reduced Mn leaching, compared to pure AMO. Therefore, it is concluded that the synthesis of AMO and biochar is able to produce a double acting sorbent ('dorbent') of enhanced efficiency, compared with the individual deployment of their component materials. Copyright © 2017 Elsevier B.V. All rights reserved.

2.0 Angstrom Structure of Prostaglandin H2 Synthase-1 Reconstituted with a Manganese Porphyrin Cofactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta,K.; Selinsky, B.; Loll, P.

2006-01-01

Prostaglandin H{sub 2} synthase (EC 1.14.99.1) is a clinically important drug target that catalyzes two key steps in the biosynthesis of the eicosanoid hormones. The enzyme contains spatially distinct cyclooxygenase and peroxidase active sites, both of which require a heme cofactor. Substitution of ferric heme by Mn{sup III} protoporphyrin IX greatly diminishes the peroxidase activity, but has little effect on the cyclooxygenase activity. Here, the 2.0 Angstrom resolution crystal structure of the Mn{sup III} form of ovine prostaglandin H{sub 2} synthase-1 is described (R = 21.8%, R{sub free} = 23.7%). Substitution of Mn{sup III} for Fe{sup III} causes no structuralmore » perturbations in the protein. However, the out-of-plane displacement of the manganese ion with respect to the porphyrin is greater than that of the iron by approximately 0.2 Angstroms. This perturbation may help to explain the altered catalytic properties of the manganese enzyme.« less

Optical and magneto-optical studies of martensitic transformation in Ni-Mn-Ga magnetic shape memory alloys

NASA Astrophysics Data System (ADS)

Beran, L.; Cejpek, P.; Kulda, M.; Antos, R.; Holy, V.; Veis, M.; Straka, L.; Heczko, O.

2015-05-01

Optical and magneto-optical properties of single crystal of Ni50.1Mn28.4Ga21.5 magnetic shape memory alloy during its transformation from martensite to austenite phase were systematically studied. Crystal orientation was approximately along {100} planes of parent cubic austenite. X-ray reciprocal mapping confirmed modulated 10 M martensite phase. Temperature depended measurements of saturation magnetization revealed the martensitic transformation at 335 K during heating. Magneto-optical spectroscopy and spectroscopic ellipsometry were measured in the sample temperature range from 297 to 373 K and photon energy range from 1.2 to 6.5 eV. Magneto-optical spectra of polar Kerr rotation as well as the spectra of ellipsometric parameter Ψ exhibited significant changes when crossing the transformation temperature. These changes were assigned to different optical properties of Ni-Mn-Ga in martensite and austenite phases due to modification of electronic structure near the Fermi energy during martensitic transformation.

Recovery of lithium from the effluent obtained in the process of spent lithium-ion batteries recycling.

PubMed

Guo, Xueyi; Cao, Xiao; Huang, Guoyong; Tian, Qinghua; Sun, Hongyu

2017-08-01

A novel process of lithium recovery as lithium ion sieve from the effluent obtained in the process of spent lithium-ion batteries recycling is developed. Through a two-stage precipitation process using Na 2 CO 3 and Na 3 PO 4 as precipitants, lithium is recovered as raw Li 2 CO 3 and pure Li 3 PO 4 , respectively. Under the best reaction condition (both the amounts of Na 2 CO 3 and Li 3 PO 4 vs. the theoretical ones are about 1.1), the corresponding recovery rates of lithium (calculated based on the concentration of the previous stage) are 74.72% and 92.21%, respectively. The raw Li 2 CO 3 containing the impurity of Na 2 CO 3 is used to prepare LiMn 2 O 4 as lithium ion sieve, and the tolerant level of sodium on its property is studied through batch tests of adsorption capacity and corrosion resistance. When the weight percentage of Na 2 CO 3 in raw Li 2 CO 3 is controlled less than 10%, the Mn corrosion percentage of LiMn 2 O 4 decreases to 21.07%, and the adsorption capacity can still keep at 40.08 mg g -1 . The results reveal that the conventional separation sodium from lithium may be avoided through the application of the raw Li 2 CO 3 in the field of lithium ion sieve. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stable isotope fractionation of tungsten during adsorption on Fe and Mn (oxyhydr)oxides

NASA Astrophysics Data System (ADS)

Kashiwabara, Teruhiko; Kubo, Sayuri; Tanaka, Masato; Senda, Ryoko; Iizuka, Tsuyoshi; Tanimizu, Masaharu; Takahashi, Yoshio

2017-05-01

The similar, but not identical chemical properties of W compared with Mo suggest that the stable isotope system of W could be a novel proxy to explore the modern and ancient ocean as is the case in the well-established utility of Mo isotopes. We experimentally investigated the isotopic fractionation of W during adsorption on Fe and Mn (oxyhydr)oxides (ferrihydrite and δ-MnO2), a key process in the global ocean budget of this element. Our adsorption experiments confirmed that W isotopes fractionate substantially on both ferrihydrite and δ-MnO2: lighter W isotopes are preferentially adsorbed on both oxides as a result of equilibrium isotopic exchange between dissolved and adsorbed species, and the obtained values of Δ186/183Wliquid-solid (= δ186Wdissolved - δ186Wadsorbed) are 0.76 ± 0.09‰ for ferrihydrite and 0.88 ± 0.21‰ for δ-MnO2 (2σ, n = 6). Compared with the case of Mo isotopes, fractionation of W isotopes is (i) of comparable magnitude between ferrihydrite and δ-MnO2, and (ii) much smaller than that of Mo on δ-MnO2. Our previous XAFS observations and newly-performed DFT calculations both indicate that the observed W isotopic fractionations are caused by the symmetry change from Td (tetrahedral) WO42- to distorted Oh (octahedral) monomeric W species via formation of inner-sphere complexes on both ferrihydrite and δ-MnO2. The similar isotopic fractionations between the two oxides relate to the strong tendency for W to form inner-sphere complexes, which causes the symmetry change, in contrast to the outer-sphere complex of Mo on ferrihydrite. The smaller isotopic fractionation of W compared with Mo on δ-MnO2 despite their similar molecular symmetry seems to be due to their different degrees of distortion of Oh species. Our findings imply that the isotopic composition of W in modern oxic seawater is likely to become heavier relative to the input by removal of lighter W isotopes via adsorption on ferromanganese oxides in analogy with the Mo isotope budget. In contrast, the isotopic composition of W in ancient seawater should have evolved in response to the extent of deposition of both Fe and Mn oxides; this is likely to be different compared with that of the Mo isotopes, which is strongly associated with the occurrence of Mn oxides relative to Fe oxides.

Zerovalent Copper Intercalated Birnessite as a Cathode for Lithium Ion Batteries: Extending Cycle Life

DOE PAGES

Li, Yue Ru; Poyraz, Altug S.; Hu, Xiaobing; ...

2017-01-01

Birnessite type layered manganese dioxides (δ-MnO 2) have attracted considerable attention in recent years as 2D intercalation cathodes for rechargeable Li +, Na +, and Mg 2+ batteries due to fast ion diffusion through their negatively charged δ-MnO 2 sheets separated by interlayer cations and a stable Mn 3+/4+ redox couple. Here we report the preparation and electrochemistry of zero and divalent copper co-intercalated birnessite type manganese dioxide (Cu 0 0.03Cu 2+ 0.21Na 0.12MnO 2·0.9H 2O). The copper intercalated birnessite materials were fully characterized utilizing powder X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM).more » The mixed valent nature of intercalated Cu 0 and Cu 2+ was confirmed by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). Electrochemical evaluation results show that zero valent copper intercalated birnessite exhibits higher discharge capability, improved cyclability, and lower impedance compared to the Cu 2+ only intercalated (Cu 0.26MnO 2·1.0H 2O) and Cu free Na birnessite (Na 0.40MnO 2·1.0H 2O) materials. Remarkably, zero valent copper birnessite shows almost no fade after 10 cycles at 0.1 mV/s. Electrochemical impedance spectroscopy results suggest that charge transfer resistivity of Cu 0 modified samples was much lower than that of Cu 2+ and Cu free birnessite, indicating that the presence of a small amount of Cu 0 improves the conductivity of birnessite and results in better electrochemical cyclability, rate capability, and lower impedance.« less

/sup 54/Mn absorption and excretion in rats fed soy protein and casein diets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, D.Y.; Johnson, P.E.

1989-02-01

Rats were fed diets containing either soy protein or casein and different levels of manganese, methionine, phytic acid, or arginine for 7 days and then fed test meals labeled with 2 microCi of 54Mn after an overnight fast. Retention of 54Mn in each rat was measured every other day for 21 days using a whole-body counter. Liver manganese was higher (P less than 0.0001) in soy protein-fed rats (8.8 micrograms/g) than in casein-fed rats (5.2 micrograms/g); manganese superoxide dismutase activity also was higher in soy protein-fed rats than in casein-fed rats (P less than 0.01). There was a significant interactionmore » between manganese and protein which affected manganese absorption and biologic half-life of 54Mn. In a second experiment, rats fed soy protein-test meals retained more 54Mn (P less than 0.001) than casein-fed rats. Liver manganese (8.3 micrograms/g) in the soy protein group was also higher than that (5.7 micrograms/g) in the casein group (P less than 0.0001), but manganese superoxide dismutase activity was unaffected by protein. Supplementation with methionine increased 54Mn retention from both soy and casein diets (P less than 0.06); activity of manganese superoxide dismutase increased (P less than 0.05) but liver manganese did not change. The addition of arginine to casein diets had little effect on manganese bioavailability. Phytic acid affected neither manganese absorption nor biologic half-life in two experiments, but it depressed liver manganese in one experiment. These results suggest that neither arginine nor phytic acid was the component in soy protein which made manganese more available from soy protein diets than casein diets.« less

From a Dy(III) single molecule magnet (SMM) to a ferromagnetic [Mn(II)Dy(III)Mn(II)] trinuclear complex.

PubMed

Bhunia, Asamanjoy; Gamer, Michael T; Ungur, Liviu; Chibotaru, Liviu F; Powell, Annie K; Lan, Yanhua; Roesky, Peter W; Menges, Fabian; Riehn, Christoph; Niedner-Schatteburg, Gereon

2012-09-17

The Schiff base compound 2,2'-{[(2-aminoethyl)imino]bis[2,1-ethanediyl-nitriloethylidyne]}bis-2-hydroxy-benzoic acid (H(4)L) as a proligand was prepared in situ. This proligand has three potential coordination pockets which make it possible to accommodate from one to three metal ions allowing for the possible formation of mono-, di-, and trinuclear complexes. Reaction of in situ prepared H(4)L with Dy(NO(3))(3)·5H(2)O resulted in the formation of a mononuclear complex [Dy(H(3)L)(2)](NO(3))·(EtOH)·8(H(2)O) (1), which shows SMM behavior. In contrast, reaction of in situ prepared H(4)L with Mn(ClO(4))(2)·6H(2)O and Dy(NO(3))(3)·5H(2)O in the presence of a base resulted in a trinuclear mixed 3d-4f complex (NHEt(3))(2)[Dy{Mn(L)}(2)](ClO(4))·2(H(2)O) (2). At low temperatures, compound 2 is a weak ferromagnet. Thus, the SMM behavior of compound 1 can be switched off by incorporating two Mn(II) ions in close proximity either side of the Dy(III). This quenching behavior is ascribed to the presence of the weak ferromagnetic interactions between the Mn(II) and Dy(III) ions, which at T > 2 K act as a fluctuating field causing the reversal of magnetization on the dysprosium ion. Mass spectrometric ion signals related to compounds 1 and 2 were both detected in positive and negative ion modes via electrospray ionization mass spectrometry. Hydrogen/deuterium exchange (HDX) reactions with ND(3) were performed in a FT-ICR Penning-trap mass spectrometer.

The Effects of Bismuth Oxide on Microstructures and Magnetic Properties of Mn-Mg-Al Ferrites

NASA Astrophysics Data System (ADS)

Nekouee, Kh. A.; Rahimi, A. H.; Haghighi, M. Alineghad; Ehsani, N.

2018-04-01

In the present paper, the effects of bismuth oxide as an additive on microstructure and magnetic properties of Mg0.9Mn0.1Al0.4Fe1.6O4 were investigated. Mg-Mn-Al ferrite powders were prepared by the conventional solid state synthesis method. Two different amounts of bismuth oxide (2.5 wt.% and 5 wt.%) were utilized as the sintering aid and their microstructure and physical properties were compared to those of the sample without additives. X-ray diffraction (XRD) analysis indicated that crystal lattice distortion due to the microstructural constraints as the result from incorporation of bismuth oxide into the microstructure was developed by adding bismuth oxide. XRD Rietveld refinement was used to define the cation distribution and to refine the lattice parameter and oxygen parameter for the sample without bismuth oxide as (Mg0.16Mn0.02Al0.15Fe0.77)A(Mg0.74Mn0.08Al0.25Fe0.83)BO4 and 8.3308 Å and 0.2542, respectively. Microstructure studies show that a bismuth rich liquid phase forms during the sintering at 1250°C, which enhances the densification of sintered bodies up to 13% (a relative density of 93%). Magnetization of sintered samples were increased from 21.1 emu/g to 26.2 emu/g upon addition of 2.5 wt.% bismuth oxide and then decreased to 24.9 emu/g when 5 wt.% bismuth oxide was added.

Bispecific Antibody Conjugated Manganese-Based Magnetic Engineered Iron Oxide for Imaging of HER2/neu- and EGFR-Expressing Tumors

PubMed Central

Wu, Shou-Cheng; Chen, Yu-Jen; Wang, Hsiang-Ching; Chou, Min-Yuan; Chang, Teng-Yuan; Yuan, Shyng-Shiou; Chen, Chiao-Yun; Hou, Ming-Feng; Hsu, John Tsu-An; Wang, Yun-Ming

2016-01-01

The overexpression of HER2/neu and EGFR receptors plays important roles in tumorigenesis and tumor progression. Targeting these two receptors simultaneously can have a more widespread application in early diagnosis of cancers. In this study, a new multifunctional nanoparticles (MnMEIO-CyTE777-(Bis)-mPEG NPs) comprising a manganese-doped iron oxide nanoparticle core (MnMEIO), a silane-amino functionalized poly(ethylene glycol) copolymer shell, a near infrared fluorescence dye (CyTE777), and a covalently conjugated anti-HER2/neu and anti-EGFR receptors bispecific antibody (Bis) were successfully developed. In vitro T2-weighted MR imaging studies in SKBR-3 and A431 tumor cells incubated with MnMEIO-CyTE777-(Bis)-mPEG NPs showed - 94.8 ± 3.8 and - 84.1 ± 2.8% negative contrast enhancement, respectively. Pharmacokinetics study showed that MnMEIO-CyTE777-(Bis)-mPEG NPs were eliminated from serum with the half-life of 21.3 mins. In vivo MR imaging showed that MnMEIO-CyTE777-(Bis)-mPEG NPs could specifically and effectively target to HER2/neu- and EGFR-expressing tumors in mice; the relative contrast enhancements were 11.8 (at 2 hrs post-injection) and 61.5 (at 24 hrs post-injection) fold higher in SKBR-3 tumors as compared to Colo-205 tumors. T2-weighted MR and optical imaging studies revealed that the new contrast agent (MnMEIO-CyTE777-(Bis)-mPEG NPs) could specifically and effectively target to HER2/neu- and/or EGFR-expressing tumors. Our results demonstrate that MnMEIO-CyTE777-(Bis)-mPEG NPs are able to recognize the tumors expressing both HER2/neu and/or EGFR, and may provide a novel molecular imaging tool for early diagnosis of cancers expressing HER2/neu and/or EGFR. PMID:26722378

Stabilization of a Metastable Fibrous Bi 21.2(1)(Mn 1–xCo x ) 20 Phase with Pseudo-Pentagonal Symmetry Prepared Using a Bi Self-Flux

DOE PAGES

Thimmaiah, Srinivasa; Taufour, Valentin; Iowa State Univ., Ames, IA; ...

2016-11-15

Bi 21.2(1)(Mn 1–xCo x ) 20 is a new metastable phase which is synthesized via Bi self-flux, adopts a highly fibrous morpholo-gy, and decomposes endothermically near 168 °C. It crystallizes in the orthorhombic space group Imma with unit cell parameters α = 19.067(4) Å, $b$ = 4.6071(10) Å and c = 11.583(4) Å, adopting a low-temperature modification of BiNi-type structure by forming columns along the b-axis. Wave-length-dispersive X-ray spectroscopy (WDS) confirms the presence of Co in the structure, which is found to be 7 at.%. In each column, the transition metal (T) and Bi atoms construct a double-walled nanotubular arrangementmore » of atoms around the disordered central Bi atoms. Electronic structure calculations (LMTO-ASA, LSDA) show that the calculated Fermi level falls into a pseudogap and also indicate a possible low-temperature magnetic ordering in the phase.« less

Magnetic damping in sputter-deposited C o2MnGe Heusler compounds with A 2 ,B 2 , and L 21 orders: Experiment and theory

NASA Astrophysics Data System (ADS)

Shaw, Justin M.; Delczeg-Czirjak, Erna K.; Edwards, Eric R. J.; Kvashnin, Yaroslav; Thonig, Danny; Schoen, Martin A. W.; Pufall, Matt; Schneider, Michael L.; Silva, Thomas J.; Karis, Olof; Rice, Katherine P.; Eriksson, Olle; Nembach, Hans T.

2018-03-01

We show that very low values of the magnetic damping parameter can be achieved in sputter deposited polycrystalline films of C o2MnGe annealed at relatively low temperatures ranging from 240 °C to 400 °C. Damping values as low as 0.0014 are obtained with an intrinsic value of 0.0010 after spin-pumping contributions are considered. Of importance to most applications is the low value of inhomogeneous linewidth that yields measured linewidths of 1.8 and 5.1 mT at 10 and 40 GHz, respectively. The damping parameter monotonically decreases as the B 2 order of the films increases. This trend is reproduced and explained by ab initio calculations of the electronic structure and damping parameter. Here, the damping parameter is calculated as the structure evolves from A 2 to B 2 to L 21 orders. The largest decrease in the damping parameter occurs during the A 2 to B 2 transition as the half-metallic phase becomes established.

Neurobehavioral Function in School-Age Children Exposed to Manganese in Drinking Water

PubMed Central

Oulhote, Youssef; Mergler, Donna; Barbeau, Benoit; Bellinger, David C.; Bouffard, Thérèse; Brodeur, Marie-Ève; Saint-Amour, Dave; Legrand, Melissa; Sauvé, Sébastien

2014-01-01

Background: Manganese neurotoxicity is well documented in individuals occupationally exposed to airborne particulates, but few data are available on risks from drinking-water exposure. Objective: We examined associations of exposure from concentrations of manganese in water and hair with memory, attention, motor function, and parent- and teacher-reported hyperactive behaviors. Methods: We recruited 375 children and measured manganese in home tap water (MnW) and hair (MnH). We estimated manganese intake from water ingestion. Using structural equation modeling, we estimated associations between neurobehavioral functions and MnH, MnW, and manganese intake from water. We evaluated exposure–response relationships using generalized additive models. Results: After adjusting for potential confounders, a 1-SD increase in log10 MnH was associated with a significant difference of –24% (95% CI: –36, –12%) SD in memory and –25% (95% CI: –41, –9%) SD in attention. The relations between log10 MnH and poorer memory and attention were linear. A 1-SD increase in log10 MnW was associated with a significant difference of –14% (95% CI: –24, –4%) SD in memory, and this relation was nonlinear, with a steeper decline in performance at MnW > 100 μg/L. A 1-SD increase in log10 manganese intake from water was associated with a significant difference of –11% (95% CI: –21, –0.4%) SD in motor function. The relation between log10 manganese intake and poorer motor function was linear. There was no significant association between manganese exposure and hyperactivity. Conclusion: Exposure to manganese in water was associated with poorer neurobehavioral performances in children, even at low levels commonly encountered in North America. Citation: Oulhote Y, Mergler D, Barbeau B, Bellinger DC, Bouffard T, Brodeur ME, Saint-Amour D, Legrand M, Sauvé S, Bouchard MF. 2014. Neurobehavioral function in school-age children exposed to manganese in drinking water. Environ Health Perspect 122:1343–1350; http://dx.doi.org/10.1289/ehp.1307918 PMID:25260096

Differences in micronucleus frequency and acrylamide adduct levels with hemoglobin between vegetarians and non-vegetarians.

PubMed

Kotova, Natalia; Frostne, Cecilia; Abramsson-Zetterberg, Lilianne; Tareke, Eden; Bergman, Rolf; Haghdoost, Siamak; Paulsson, Birgit; Törnqvist, Margareta; Segerbäck, Dan; Jenssen, Dag; Grawé, Jan

2015-10-01

Nutrients and food constituents can prevent or contribute to genotoxicity. In this study, the possible influence of a vegetarian/non-vegetarian diet on genotoxic effects was investigated in 58 non-smoking healthy vegetarians (V) and non-vegetarians (NV), age 21-37 years from the Stockholm area in Sweden. Physical activity and dietary habits were similar in both groups, with the exception of the intake of meat and fish. Using flow cytometry, we determined the formation of micronuclei (MN) in transferrin-positive immature peripheral blood reticulocytes (Trf-Ret) (Total: n = 53; V: n = 27; NV: n = 26). Dietary exposure to acrylamide was measured through hemoglobin (Hb) adducts in peripheral erythrocytes (Total: n = 53; V: n = 29; NV: n = 24). Hb adducts of both acrylamide and its genotoxic metabolite glycidamide were monitored as a measure of the corresponding in vivo doses. Our data demonstrated that compared with the non-vegetarians, the vegetarians exhibited lower frequencies of MN (fMN) in the Trf-Ret (p < 0.01, Student's t test). A multivariate analysis demonstrated that there was no association between the fMN and factors such as age, sex, intake of vitamins/minerals, serum folic acid and vitamin B12 levels, physical activity, and body mass index. The mean Hb adduct levels of acrylamide and glycidamide showed no significant differences between vegetarians and non-vegetarians. Furthermore, there were no significant relationships between the adduct levels and fMN in the individuals. The ratio of the Hb adduct levels from glycidamide and acrylamide, however, showed a significant difference (p < 0.04) between the two groups. These data suggest that the vegetarian diet might be beneficial in lowering genomic instability in healthy individuals. The measured Hb adduct levels indicate that the total intake of acrylamide does not differ between the two studied groups and does not contribute to the observed difference in fMN, although an influence of the diet on the metabolic rates of acrylamide was indicated. In addition, the observed significant difference in the background fMN in the two groups demonstrated that the MN analysis method has a sensitivity applicable to the biomonitoring of human lifestyle factors.

Processing of Mn-Al nanostructured magnets by spark plasma sintering and subsequent rapid thermal annealing

NASA Astrophysics Data System (ADS)

Saravanan, P.; Vinod, V. T. P.; Černík, Miroslav; Selvapriya, A.; Chakravarty, Dibyendu; Kamat, S. V.

2015-01-01

The potential of spark plasma sintering (SPS) in combination with rapid thermal annealing (RTA) for the processing of Mn-Al nanostructured magnets is explored in this study. Ferromagnetic α-Mn alloy powders were processed by high-energy ball milling using Mn (56 at%) and Al (44 at%) as constituent metal elements. The alloying action between Mn and Al due to intensive milling was studied by X-ray diffraction and field-emission scanning electron microscope; while the phase transformation kinetics was investigated using differential scanning calorimetry. The evolution of ferromagnetic properties in the as-milled powders was studied by superconducting quantum interference device (SQUID). Among the Mn-Al alloy powders collected at various milling intervals, the 25 h milled Mn-Al powders showed a good combination of coercivity, Hc (11.3 kA/m) and saturation magnetization, Ms (5.0 A/m2/kg); accordingly, these powders were chosen for SPS. The SPS experiments were conducted at different temperatures: 773, 873 and 973 K and its effect on the density, phase composition and magnetic properties of the Mn-Al bulk samples were investigated. Upon increasing the SPS temperature from 773 to 973 K, the bulk density was found to increase from 3.6 to 4.0 g/cm3. The occurrence of equilibrium β-phase with significant amount of γ2-phase was obvious at all the SPS temperatures; however, crystallization of some amount of τ-phase was evident at 973 K. Irrespective of the SPS temperatures, all the samples demonstrated soft magnetic behavior with Hc and Ms values similar to those obtained for the 25 h milled powders. The magnetic properties of the SPSed samples were significantly improved upon subjecting them to RTA at 1100 K. Through the RTA process, Hc values of 75, 174 and 194 kA/m and Ms values of 19, 21 and 28 A/m2/kg were achieved for the samples SPSed at 773, 873 and 973 K, respectively. The possible reasons for the observed improvement in the magnetic properties of the SPSed samples due to RTA in correlation with their phase composition and microstructure were analyzed and discussed.

Analysis of urinary metanephrines by reversed-phase high-performance liquid chromatography and electrochemical detection.

PubMed

Bertani-Dziedzic, L M; Krstulovic, A M; Dziedzic, S W; Gitlow, S E; Cerqueira, S

1981-02-19

A sensitive and specific direct analysis of urinary normetanephrine (NMN) and metanephrine (MN) was achieved utilizing reversed-phase high performance liquid chromatography and electrochemical detection. Individual specimens from "control" subjects and those with pheochromocytoma were hydrolyzed and the metanephrines separated from other urinary constituents by elution with ammonia from a Dowex CG-50 resin. Chromatographic peaks were identified by retention behavior, co-chromatography with reference compounds, ratio of responses at various oxidation potentials and stopped-flow UV spectra of the collected fractions. The NMN and MN content for the control subjects was between 0.086 and 0.21 (mean - 0.14) microgram/mg creatinine and 0.012 and 0.092 (mean = 0.039) microgram/mg creatinine, respectively. The values for subjects with pheochromocytoma varied from 1.5 to 27.5 (mean = 9.9) microgram/mg creatinine for NMN and 0.10 to 1.60 (mean = 0.86) microgram/mg creatine for MN. The patient with ganglioneuroma had an NMN of 4.1 and an MN of 0.80 microgram/mg creatinine. While this method permits discrimination between those patients with pheochromocytoma and the overwhelming majority of hypertensive patients, it may ultimately be further extended to separate normal subjects from those with more subtle derangements in catecholamine metabolism.

Magnetotransport properties of microstructured AlCu2Mn Heusler alloy thin films in the amorphous and crystalline phase

NASA Astrophysics Data System (ADS)

Barzola-Quiquia, José; Stiller, Markus; Esquinazi, Pablo D.; Quispe-Marcatoma, Justiniano; Häussler, Peter

2018-06-01

We have studied the resistance, magnetoresistance and Hall effect of AlCu2Mn Heusler alloy thin films prepared by flash evaporation on substrates cooled at 4He liquid temperature. The as-prepared samples were amorphous and were annealed stepwise to induce the transformation to the crystalline phase. The amorphous phase is metastable up to above room temperature and the transition to the crystalline phase was observed by means of resistance measurements. Using transmission electron microscopy, we have determined the structure factor S (K) and the pair correlation function g (r) , both results indicate that amorphous AlCu2Mn is an electronic stabilized phase. The X-ray diffraction of the crystallized film shows peaks corresponding to the well ordered L21 phase. The resistance shows a negative temperature coefficient in both phases. The magnetoresistance (MR) is negative in both phases, yet larger in the crystalline state compared to the amorphous one. The magnetic properties were studied further by anomalous Hall effect measurements, which were present in both phases. In the amorphous state, the anomalous Hall effect disappears at temperatures below 175 K and is present up to above room temperature in the case of crystalline AlCu2Mn.

Proton scattering on 40S

NASA Astrophysics Data System (ADS)

Maréchal, F.; Suomijärvi, T.; Blumenfeld, Y.; Azhari, A.; Bazin, D.; Brown, J. A.; Cottle, P. D.; Fauerbach, M.; Glasmacher, T.; Hirzebruch, S. E.; Jewell, J. K.; Kemper, K. W.; Mantica, P. F.; Morrissey, D. J.; Riley, L. A.; Scarpaci, J. A.; Steiner, M.

1998-12-01

We have recently studied the structure of the neutron rich sulfur isotope 40S by using elastic and inelastic proton scattering in inverse kinematics. Optical potential and folding model calculations are compared with the elastic and inelastic angular distributions. Using coupled-channel calculations, the β2 value for the 21+ excited state is determined to be 0.35±0.05. The extracted value of Mn/Mp ratio indicates a small isovector contribution to the 21+ state of 40S. The microscopic analysis of the data is compatible with the presence of a neutron skin for this nucleus.

Nonequivalence of chemical and hydrostatic pressures: A1g and Eg frequencies and Stokes shift of Mn2+-doped perovskites

NASA Astrophysics Data System (ADS)

Barriuso, M. T.; Moreno, M.; Aramburu, J. A.

2002-02-01

The frequency of A1g and Eg modes of MnF4-6 in cubic ABF3 (A: K; B: Mg, Zn and A: Rb, Cs; B: Cd, Ca) perovskites has been derived through density functional calculations on MnF6A8B16+6 clusters which reproduce the experimental impurity-ligand distance Re. Both frequencies are found to experience a drastic decrement on passing from KMgF3:Mn2+ (ħωA=556 cm-1, ħωE=456 cm-1) to CsCdF3:Mn2+ (ħωA=317 cm-1, ħωE=239 cm-1) despite the fact that Re increases only by 5%, leading to effective Grüneisen constants (called γcA and γcE) around 3.0 along the series. This figure is 60% higher than the usual Grüneisen constant γA calculated for a given system like KMgF3:Mn2+ or KZnF3:Mn2+ when hydrostatic pressure is applied. For supporting this relevant result the value of γA for CrF3-6 in a fluoroelpasolite has been calculated as well. The obtained value γA=2.1 is close to the experimental one (γA=1.9) derived in K2NaGaF6:Cr3+ by combined optical and Raman measurements. As a salient feature, the increase of the Stokes shift when Re increases observed along the ABF3:Mn2+ series is now well explained through the bigger variations of A1g and Eg frequencies induced by the chemical pressure in comparison to those coming from an hydrostatic pressure on a given system. The difference between γcA and γA is discussed through a simple model that emphasizes the role played by the coupling of the MnF4-6 complex to the lattice. The influence of chemical and hydrostatic pressures upon the luminescence efficiency is also briefly discussed. Attention is addressed to the method of calculating impurity-associated Grüneisen constants using clusters. Recent results on Cr3+ in several cubic chloroelpasolites that support the present conclusions are briefly discussed as well.

Barium isotope fractionation during experimental formation of the double carbonate BaMn[CO3](2) at ambient temperature.

PubMed

Böttcher, Michael E; Geprägs, Patrizia; Neubert, Nadja; von Allmen, Katja; Pretet, Chloé; Samankassou, Elias; Nägler, Thomas F

2012-09-01

In this study, we present the first experimental results for stable barium (Ba) isotope ((137)Ba/(134)Ba) fractionation during low-temperature formation of the anhydrous double carbonate BaMn[CO(3)](2). This investigation is part of an ongoing work on Ba fractionation in the natural barium cycle. Precipitation at a temperature of 21±1°C leads to an enrichment of the lighter Ba isotope described by an enrichment factor of-0.11±0.06‰ in the double carbonate than in an aqueous barium-manganese(II) chloride/sodium bicarbonate solution, which is within the range of previous reports for synthetic pure BaCO (3) (witherite) formation.

Magnetic Properties and Phase Diagram of Ni50Mn_{50-x}Ga_{x/2}In_{x/2} Magnetic Shape Memory Alloys

NASA Astrophysics Data System (ADS)

Xu, Xiao; Yoshida, Yasuki; Omori, Toshihiro; Kanomata, Takeshi; Kainuma, Ryosuke

2016-12-01

Ni50Mn50- x Ga x/2In x/2 magnetic shape memory alloys were systematically prepared, and the magnetic properties as well as the phase diagram, including atomic ordering, martensitic and magnetic transitions, were investigated. The B2- L21 order-disorder transformation showed a parabolic-like curve against the Ga+In composition. The martensitic transformation temperature was found to decrease with increasing Ga+In composition and to slightly bend downwards below the Curie temperature of the parent phase. Spontaneous magnetization was investigated for both parent and martensite alloys. The magnetism of martensite phase was found to show glassy magnetic behaviors by thermomagnetization and AC susceptibility measurements.

SMART- Small Motor AerRospace Technology

NASA Astrophysics Data System (ADS)

Balucani, M.; Crescenzi, R.; Ferrari, A.; Guarrea, G.; Pontetti, G.; Orsini, F.; Quattrino, L.; Viola, F.

2004-11-01

This paper presents the "SMART" (Small Motor AerRospace Tecnology) propulsion system, constituted of microthrusters array realised by semiconductor technology on silicon wafers. SMART system is obtained gluing three main modules: combustion chambers, igniters and nozzles. The module was then filled with propellant and closed by gluing a piece of silicon wafer in the back side of the combustion chambers. The complete assembled module composed of 25 micro- thrusters with a 3 x 5 nozzle is presented. The measurement showed a thrust of 129 mN and impulse of 56,8 mNs burning about 70mg of propellant for the micro-thruster with nozzle and a thrust of 21 mN and impulse of 8,4 mNs for the micro-thruster without nozzle.

Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels

PubMed Central

Ha, Heon-Young; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Sangshik

2017-01-01

Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis. PMID:28772651

A geochronological 40Ar/39Ar and 87Rb/81Sr study of K-Mn oxides from the weathering sequence of Azul, Brazil

NASA Astrophysics Data System (ADS)

Ruffet, G.; Innocent, C.; Michard, A.; Féraud, G.; Beauvais, A.; Nahon, D.; Hamelin, B.

1996-06-01

KMn oxides of hollandite group minerals such as cryptomelane (K 1-2(Mn 3+, Mn 4+) 8O 16nH 2O) are often precipitated authigenically in weathering profiles. The presence of structural K allows these minerals to be dated by the KAr and 40Ar/ 39Ar methods, making it possible to study the progression of oxidation fronts during weathering processes. Within the context of a recent 40Ar/ 39Ar study of cryptomelane from the Azul Mn deposit in the Carajàs region (Amazônia, Brazil), Vasconcelos et al. (1994) defined three age clusters (65-69, 51-56, and 40-43 Ma) and proposed that they correspond to the episodic precipitation of the three generations of Mn oxide that have been identified in the deposit (Beauvais et al., 1987). We performed a laser probe 40Ar/ 39Ar and 87Rb/ 87Sr study on new samples from the same Mn deposit. Our 40Ar/ 39Ar data confirm that cryptomelane is a suitable mineral for 40Ar/ 39Ar dating, although in some cases we clearly identify the existence of 39Ar recoil effects. Although the corresponding age spectra are generally strongly disturbed, our results also confirm that the earliest cryptomelane generation is of Upper Cretaceous-Paleocene age. We obtained good plateau ages from veins and concretions of the second cryptomelane generation. Some of these results allow definition of a well-constrained age cluster at 46.7-48.1 Ma not observed by Vasconcelos et al. (1994). A petrographic study confirms that none of the samples analyzed in the present study contained material associated with the third generation of cryptomelane. We propose that these new results support the idea of a more or less continuous crystallization of KMn oxides, mainly constrained by local factors, rather than the model advanced by Vasconcelos et al. (1994), which suggests that each cryptomelane generation corresponds to distinct weathering events related to global climatic changes. 87Sr/ 86Sr data show large variations, clearly inherited from the 2.1 Ga parent rock of the Mn protore. The Rb/Sr results demonstrate that minimum fractionation occurs during cryptomelane crystallization, except for the latest generation, which is depleted in Sr. This precludes use of the Rb/Sr radiochronometer for dating secondary Mn oxides in laterites.

Effects of gender, ejection fraction and weight on cardiac force development in patients undergoing cardiac surgery--an experimental examination.

PubMed

Bening, Constanze; Weiler, Helge; Vahl, Christian-Friedrich

2013-11-18

It has long been recognized that differences exist between men and women in the impact of risc factors, symptoms, development and outcome of special diseases like the cardiovascular disease. Gender determines the cardiac baseline parameters like the number of cardiac myocyte, size and demand and may suggest differences in myofilament function among genders, which might be pronounced under pathological conditions. Does gender impact and maybe impair the contractile apparatus? Are the differences more prominent when other factors like weight, age, ejection fraction are added?Therefore we performed a study on 36 patients (21 male, 15 female) undergoing aortic valve replacement (AVR) or aortocoronary bypass operation (CABG) to examine the influence of gender, ejection fraction, surgical procedure and body mass index (BMI) on cardiac force development. Tissue was obtained from the right auricle and was stored in a special solution to prevent any stretching of the fibers. We used the skinned muscle fiber model and single muscle stripes, which were mounted on the "muscle machine" and exposed to a gradual increase of calcium concentration calculated by an attached computer program. 1.) In general female fibers show more force than male fibers: 3.9 mN vs. 2.0 mN (p = 0.03) 2.) Female fibers undergoing AVR achieved more force than those undergoing CABG operation: 5.7 mN vs. 2.8 mN (p = 0.02) as well as male fibers with AVR showed more force values compared to those undergoing CABG: 2.0 mN vs. 0.5 mN (p = 0.01). 3.) Male and female fibers of patients with EF > 55% developed significantly more force than from those with less ejection fraction than 30%: p = 0.002 for the male fibers (1.6 vs. 2.8 mN) and p = 0.04 for the female fibers (5.7 vs. 2.8 mN). 4.) Patients with a BMI between 18 till 25 develop significant more force than those with a BMI > 30: Females 5.1 vs. 2.6 mN; p 0.03, Males 3.8 vs. 0.8 mN; p 0.04). Our data suggest that female patients undergoing AVR or CABG develop significantly more force than male fibers. Additionally we could image the clinical impression of negative impact of overweight and obesity as well as low ejection fraction on cardiac function on level of the myofilaments and observed a reduced force capacity, which is more prominent in male fibers.

77 FR 68122 - Formations of, Acquisitions by, and Mergers of Savings and Loan Holding Companies

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-15

..., Minneapolis, Minnesota 55480-0291: 1. The Miller Family 2012 Trust U/A Dated December 21, 2012, St. Cloud... Services of Saint Cloud, Inc., Saint Cloud, MN, and thereby indirectly acquire control of Liberty Savings Bank, FSB, Saint Cloud, Minnesota. Board of Governors of the Federal Reserve System, November 9, 2012...

Report of the 2016 Uniform Regional Scab Nursery for spring wheat parents

USDA-ARS?s Scientific Manuscript database

The Uniform Regional Scab Nursery for Spring Wheat Parents (URSN) was grown for the 21st year in 2016. Five locations (Brookings, SD, St. Paul and Crookston, MN, Prosper, ND, and Morden, Canada) reported results. A total of 33 entries was included in the 2016 URSN, in addition to the resistant chec...

77 FR 40613 - Notice to All Interested Parties of the Termination of the Receivership of 10240, Pinehurst Bank...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-10

... Receivership of 10240, Pinehurst Bank, St. Paul, MN Notice is hereby given that the Federal Deposit Insurance Corporation (``FDIC'') as Receiver for Pinehurst Bank, (``the Receiver'') intends to terminate its receivership for said institution. The FDIC was appointed receiver of Pinehurst Bank on May 21, 2010. The...

Dietary carotenoid-rich oil supplementation improves exercise-induced anisocytosis in runners: influences of haptoglobin, MnSOD (Val9Ala), CAT (21A/T) and GPX1 (Pro198Leu) gene polymorphisms in dilutional pseudoanemia (sports anemia).

PubMed

Miranda-Vilela, Ana L; Akimoto, Arthur K; Alves, Penha C Z; Pereira, Luiz C S; Klautau-Guimarães, Maria N; Grisolia, Cesar K

2010-04-01

Physical training induces beneficial adaptation, whereas exhaustive exercises increase reactive oxygen-species generation, thereby causing oxidative damage in plasma and erythrocytes, fractions susceptible to lipid peroxidation. Pequi (Caryocar brasiliense Camb.) is a Brazilian Cerrado fruit containing a carotenoid-rich oil. The aim was to investigate the effects of pequi-oil on exercise-induced oxidative damage in plasma and erythrocytes, after running in the same environment and undergoing weekly training under the same conditions as to type, intensity and length. Evaluations were accomplished after outdoor running on flat land before and after ingestion of 400 mg pequi-oil capsules for 14 days. Blood samples were taken after running and submitted to TBARS assay and erythrogram analysis. Haptoglobin, MnSOD (Val9Ala), CAT (21A/T) and GPX1 (Pro198Leu) gene polymorphisms were priorly investigated, so as to estimate genetic influence The reduction in erythrocytes, hemoglobin and hematocrit after pequi-oil treatment was notably associated with higher plasma expansion. Except for MCHC (mean corpuscular hemoglobin concentration) and RDW (red cell distribution width), the results were influenced by the polymorphisms studied. The best response to pequi-oil was presented by MnSOD Val/Val, CAT AA or AT genotypes and the GPX1 Pro allele. The significantly lower RDW and higher MHCH values were related to pequi-oil protective effects. Pequi oil, besides possessing other nutritional properties, showed protective blood effects.

Sustainable recovery of valuable metals from spent lithium-ion batteries using DL-malic acid: Leaching and kinetics aspect.

PubMed

Sun, Conghao; Xu, Liping; Chen, Xiangping; Qiu, Tianyun; Zhou, Tao

2018-02-01

An eco-friendly and benign process has been investigated for the dissolution of Li, Co, Ni, and Mn from the cathode materials of spent LiNi 1/3 Co 1/3 Mn 1/3 O 2 batteries, using DL-malic acid as the leaching agent in this study. The leaching efficiencies of Li, Co, Ni, and Mn can reach about 98.9%, 94.3%, 95.1%, and 96.4%, respectively, under the leaching conditions of DL-malic acid concentration of 1.2 M, hydrogen peroxide content of 1.5 vol.%, solid-to-liquid ratio of 40 g l -1 , leaching temperature of 80°C, and leaching time of 30 min. In addition, the leaching kinetic was investigated based on the shrinking model and the results reveal that the leaching reaction is controlled by chemical reactions within 10 min with activation energies (Ea) of 21.3 kJ·mol -1 , 30.4 kJ·mol -1 , 27.9 kJ·mol -1 , and 26.2 kJ·mol -1 for Li, Co, Ni, and Mn, respectively. Diffusion process becomes the controlled step with a prolonged leaching time from 15 to 30 min, and the activation energies (Ea) are 20.2 kJ·mol -1 , 28.9 kJ·mol -1 , 26.3 kJ·mol -1 , and 25.0 kJ·mol -1 for Li, Co, Ni, and Mn, respectively. This hydrometallurgical route was found to be effective and environmentally friendly for leaching metals from spent lithium batteries.

Uptake and transport of manganese in primary and secondary olfactory neurones in pike.

PubMed

Tjälve, H; Mejàre, C; Borg-Neczak, K

1995-07-01

gamma-spectrometry and autoradiography were used to examine the axoplasmic flow of manganese in the olfactory nerves and to study the uptake of the metal in the brain after application of 54Mn2+ in the olfactory chambers of pikes. The results show that the 54Mn2+ is taken up in the olfactory receptor cells and is transported at a constant rate along the primary olfactory neurones into the brain. The maximal velocity for the transported 54Mn2+ was 2.90 +/- 0.21 mm/hr (mean +/- S.E.) at 10 degrees, which was the temperature used in the experiments. The 54Mn2+ accumulated in the entire olfactory bulbs, although most marked in central and caudal parts. The metal was also seen to migrate into large areas of the telencephalon, apparently mainly via the secondary olfactory axons present in the medial olfactory tract. A transfer along fibres of the medial olfactory tract probably also explains the labelling which was seen in the diencephalon down to the hypothalamus. The results also showed that there is a pathway connecting the two olfactory bulbs of the pike and that this can carry the metal. Our data further showed a marked accumulation of 54Mn2+ in the meningeal epithelium and in the contents of the meningeal sacs surrounding the olfactory bulbs. It appears from our study that manganese has the ability to pass the synaptic junctions between the primary and the secondary olfactory neurones in the olfactory bulbs and to migrate along secondary olfactory pathways into the telencephalon and the diencephalon.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of inflammation on plasma zinc concentration in apparently healthy, HIV+ Kenyan adults and zinc responses after a multi-micronutrient supplement.

PubMed

Mburu, A S W; Thurnham, D I; Mwaniki, D L; Muniu, E M; Alumasa, F M

2010-05-01

Plasma zinc is an important biomarker of zinc status, but the concentration is depressed by inflammation. Apparently healthy adults, who tested positive twice for human immunodeficiency virus (HIV) but who had not reached stage IV or clinical AIDS, were randomly allocated to receive a food supplement (n=17 and 21) or the food plus a micronutrient capsule (MN; n=10 men and n=33 women) containing 15 mg zinc/day. We used the inflammation biomarkers, C-reactive protein (CRP) and alpha1-acid glycoprotein (AGP), to identify subjects with and without inflammation and determine the effect of inflammation on the response of plasma zinc concentrations to the MN and food supplements. There were no differences between men and women either in plasma zinc or in the responses to the supplements and their data were combined. Plasma zinc was lower in those with inflammation than without. Repeated measures analysis of variance (ANOVA) showed that inflammation blocked increases in plasma zinc, and there was an approximate 10% increase in plasma zinc concentration in response to the MN supplement (P=0.023) in those without inflammation. Subgroup analysis showed mean changes in plasma zinc of 0.95 and -0.83 micromol/l (P=0.031) in response to the MN and food treatments, respectively, in those without inflammation at both time points. Inflammation seems to block any increase in plasma zinc after MN supplement and it is important to identify those without inflammation to determine the effectiveness of a zinc supplementation program.

Studying dielectric mechanism and magnetization of double perovskite Gd2NiMnO6 ceramic

NASA Astrophysics Data System (ADS)

Mohapatra, S. R.; Sahu, B.; Kaushik, S. D.; Singh, A. K.

2016-05-01

In the present work, the structure, dielectric and magnetic properties of Gd2NiMnO6 double perovskite have been studied. X-Ray diffraction study reveals the phase pure formation of the material that crystallizes into monoclinic phase (space group 'P21/n'). Surface morphology depicts heterogeneous grain distribution with average grain size of ~1 µm. Temperature dependent (50 - 330 K) dielectric measurements at different frequencies (0.5 - 50 kHz) relate to Maxwell-Wagner interfacial polarization model. Giant dielectric constant at 1 kHz for 300 K (ɛ' ~1900) is noticed as compared to that of 50 K (ɛ' ~10) coupled with a peak shift in tan loss towards higher temperature with frequency. The activation energy (0.24 eV) obtained using Arrhenius relation for thermally activated relaxor behavior of the material signifies an electron hopping mechanism between Ni2+ and Mn4+ cations. Lastly, M-H study shows `S' shape hysteresis loop at 50 K with remnant magnetization (Mr) of 0.72 µB/f.u. along with a linear plot for 300 K which reveals paramagnetic nature of the material.

Magnetic and crystallographic properties of ZrM 2-δZn 20+δ (M=Cr–Cu)

DOE PAGES

Svanidze, E.; II, M. Kindy; Georgen, C.; ...

2016-04-29

Single crystals of the cubic Laves ternaries ZrM 2-δZn 20+δ (M=Mn, Fe, Co, Ni and Cu, 0 ≤ δ ≤ 1) have been synthesized in this paper using a self-flux method. The magnetic properties of these compounds were compared with structurally similar cubic binaries ZrM 2 (M=Mn, Fe, Co, Ni and Cu). A transition from local to itinerant moment magnetism was observed for M=Fe and M=Mn, while all other ternaries exhibit weakly para- or diamagnetic behavior. The local-to-itinerant crossover can be explained by a nearly two-fold increase of the M–M bond length d M–M in ZrM 2-δZn 20+δ compounds, asmore » compared with the ZrM 2 binaries. Additionally, we report two new compounds in this series ZrCrZn 21 and ZrCu 2Zn 20. Finally, analysis of crystallographic and magnetic trends in these materials will aid in understanding of magnetism in general and 3d intermetallics in particular.« less

Organic trace mineral levels in the first 96-h post-hatch impact growth performance and intestinal gene expression in broiler chicks.

PubMed

Brennan, K M; Samuel, R S; Graugnard, T Ao; Xiao, R; Cantor, A H; Pescatore, A J

2013-12-01

Alterations in nutrient intake in the avian neonatal posthatch period can impact development, performance, and metabolism in adulthood. Very little is known about how mineral levels during the post-hatch period affect or “program” gene expression patterns later in life. The objective of this study was to determine the effect of post-hatch (0 to 96 h) dietary mineral supplementation on performance, tissue mineral content, and intestinal gene expression profiles in 21-day-old broiler chicks. One-day-old chicks were randomly assigned to one of two treatment groups consisting of N (organic Zn, Cu, and Mn provided at 100 % of recommendations (National Research Council 1994)) and/or L (organic Zn, Cu, and Mn provided at 20 % of recommendations (National Research Council 1994)) diets fed in two intervals (days 1–4, days 5–21) as follows: (1)N–Lor (2)L–L. Performance parameters did not differ between treatments except that body weight gain was greater (P < 0.05) in L–L birds than N–L birds over the experimental period. Bone mineral content was similar for both treatments at day 21. Intestinal gene expression profiling was examined using the Affymetrix GeneChip Chicken genome array. Ingenuity pathway analysis revealed differences in gene expression profiles between N and L treatments at day 5. At day 21, profiles were unique between N–L and L–L, suggesting that the diet fed until day 4 had an impact on gene expression patterns at day 21 even when birds were fed the same diets day 5–day 21. In this study, we demonstrated that diets fed for the 96 h post-hatch had long-term effects on gene expression, providing unique information as to why post-hatch diets are so important for the longterm bird health and productivity.

Atomic data on inelastic processes in low-energy manganese-hydrogen collisions

NASA Astrophysics Data System (ADS)

Belyaev, Andrey K.; Voronov, Yaroslav V.

2017-10-01

Aims: The aim of this paper is to calculate cross sections and rate coefficients for inelastic processes in low-energy Mn + H and Mn+ + H- collisions, especially, for processes with high and moderate rate coefficients. These processes are required for non-local thermodynamic equilibrium (non-LTE) modeling of manganese spectra in cool stellar atmospheres, and in particular, for metal-poor stars. Methods: The calculations of the cross sections and the rate coefficients were performed by means of the quantum model approach within the framework of the Born-Oppenheimer formalism, that is, the asymptotic semi-empirical method for the electronic MnH molecular structure calculation followed by the nonadiabatic nuclear dynamical calculation by means of the multichannel analytic formulas. Results: The cross sections and the rate coefficients for low-energy inelastic processes in manganese-hydrogen collisions are calculated for all transitions between 21 low-lying covalent states and one ionic state. We show that the highest values of the cross sections and the rate coefficients correspond to the mutual neutralization processes into the final atomic states Mn(3d54s(7S)5s e 6S), Mn(3d54s(7S)5p y 8P°), Mn(3d54s(7S)5s e 8S), Mn(3d54s(7S)4d e 8D) [the first group], the processes with the rate coefficients (at temperature T = 6000 K) of the values 4.38 × 10-8, 2.72 × 10-8, 1.98 × 10-8, and 1.59 × 10-8 cm3/ s, respectively, that is, with the rate coefficients exceeding 10-8 cm3/ s. The processes with moderate rate coefficients, that is, with values between 10-10 and 10-8 cm3/ s include many excitation, de-excitation, mutual neutralization and ion-pair formation processes. In addition to other processes involving the atomic states from the first group, the processes from the second group include those involving the following atomic states: Mn(3d5(6S)4s4p (1P°) y 6P°), Mn(3d54s(7S)4d e 6D), Mn(3d54s(7S)5p w 6P°), Mn(3d5(4P)4s4p (3P°) y 6D°), Mn(3d5(4G)4s4p (3P°) y 6F°). The processes with the highest and moderate rate coefficients are expected to be important for non-LTE modeling of manganese spectra in stellar atmospheres. Rate coefficients Kif(T) for the excitation, de-excitation, mutual neutralization, and ion-pair formation processes in manganese-hydrogen collisions are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A106

Significance of groundwater discharge along the coast of Poland as a source of dissolved metals to the southern Baltic Sea

USGS Publications Warehouse

Szymczycha, Beata; Kroeger, Kevin D.; Pempkowiak, Janusz

2016-01-01

Fluxes of dissolved trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) via groundwater discharge along the southern Baltic Sea have been assessed for the first time. Dissolved metal concentrations in groundwater samples were less variable than in seawater and were generally one or two orders of magnitude higher: Cd (2.1–2.8 nmol L− 1), Co (8.70–8.76 nmol L− 1), Cr (18.1–18.5 nmol L− 1), Mn (2.4–2.8 μmol L− 1), Pb (1.2–1.5 nmol L− 1), Zn (33.1–34.0 nmol L− 1). Concentrations of Cu (0.5–0.8 nmol L− 1) and Ni (4.9–5.8 nmol L− 1) were, respectively, 32 and 4 times lower, than in seawater. Groundwater-derived trace metal fluxes constitute 93% for Cd, 80% for Co, 91% for Cr, 6% for Cu, 66% for Mn, 4% for Ni, 70% for Pb and 93% for Zn of the total freshwater trace metal flux to the Bay of Puck. Groundwater-seawater mixing, redox conditions and Mn-cycling are the main processes responsible for trace metal distribution in groundwater discharge sites.

Synthesis, characterization, experimental and theoretical structure of novel Dichloro(bis{2-[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) compounds, metal = Mn, Co and Ni

NASA Astrophysics Data System (ADS)

Conradie, J.; Conradie, M. M.; Tawfiq, K. M.; Al-Jeboori, M. J.; Coles, S. J.; Wilson, C.; Potgieter, J. H.

2018-06-01

The syntheses, characterizations and structures of three novel dichloro(bis{2-[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II), [M(L)2Cl2], complexes (metal = Mn, Co and Ni) are presented. In the solid state the molecules are arranged in infinite hydrogen-bonded 3D supramolecular structures, further stabilized by weak intermolecular π…π interactions. The DFT results for all the different spin states and isomers of dichloro(bis{2-[1-phenyl-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) complexes, [M(L1)2Cl2], support experimental measurements, namely that (i) d5 [Mn(L1)2Cl2] is high spin with S = 5/2; (ii) d7 [Co(L1)2Cl2] has a spin state of S = 3/2, (iii) d8 [Ni(L1)2Cl2] has a spin state of S = 1; and (iv) for all [M(L1)2Cl2] and [M(L)2Cl2] complexes, with M = Mn, Co and Ni, the cis-cis-trans and the trans-trans-trans isomers, with the pyridyl groups trans to each other, have the lowest energy.

Magnetic and thermodynamic properties of Heusler alloys Ni55Mn26Al19

NASA Astrophysics Data System (ADS)

Ito, Masakazu; Onda, Keijiro; Taira, Atsushi; Sonoda, Kazuki; Hiroi, Masahiko; Uwatoko, Yoshiya

2018-05-01

The temperature dependence of magnetization, M(T), specific heat, Cp(T), and thermal expansion, ΔL/L300K(T) were investigated for the Heusler compound Ni55Mn26Al19 with B2 structure. M(T) has a cusp-type anomaly for the antiferromagnetic (AF) transition at the Néel temperature TN = 280 K that is irreversible between the field-cooled and zero-field-cooled processes below Tf ˜ 60 K, which is characteristic of spin glass. Cp(T) also has an anomaly at TN = 280 K. For temperatures T < 280 K, Cp(T) shows no anomaly without indicating any phase transition. These results mean that with decreasing T Ni55Mn26Al19 has a reentrant spin glass below Tf from the AF state. ΔL/L300K(T) shows no discontinuity indicating a structural transition in the range 5 < T < 300 K, i.e., Ni55Mn26Al19 has no martensitic transformation. TN increases proportionally with pressure, P, because of the enhancement of the AF interaction. The value of its initial rate is estimated to be d/TN d P = 5.25 K/GPa. Tf also increases proportionally with P with d/Tf d P = 2.21 K/GPa, and hence magnetic frustration, which promotes the spin glass system, is enhanced under pressurization.

Evaluation of Zr(Ni, Mn){sub 2} Laves phase alloys as negative active material for Ni-MH electric vehicle batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knosp, B.; Jordy, C.; Blanchard, P.

1998-05-01

Laves phase alloys of compositions (Zr, Ti)(Ni, Mn, M){sub x} where M = Cr, V, Co, Al, and 1.9 < x < 2.1 with hexagonal C14 or cubic C15 structure have been studied in order to select the most suitable AB{sub 2} alloys as an active material for nickel-metal hydride (Ni-MH) batteries. With the selected alloy, feasibility of MH negative electrodes using industrial technology and containing more than 97% of the alloy powder has been demonstrated. 22 Ah Ni-MH batteries for electric vehicle application have been assembled, and 600 cycles have been achieved at steady C/3 charge and discharge ratesmore » and 80% depth of discharge.« less

[Determination of metal elements in Achyranthis bidentatae radix from various habitats].

PubMed

Tu, Wan-Qian; Zhang, Liu-Ji

2011-12-01

To establish an atomic absorption spectrometry method for determination of the contents of metal elements in Achyranthis Bidentatae Radix and analyze 21 batches of samples from different areas. Fe, Mn, Ca, Mg, K, Zn and Cu were detected by atomic absorption spectrometry with hydrogen flame detector, Pb, As and Cd were detected by graphite furnace atomic absorption, Hg was detected by cold atomic absorption. The heavy metal contents met the requirement of Chinese Pharmacopoeia. The contents of K, Mg, Cu and Mn in the samples of geo-authentic areas were higher,while the contents of Fe, Zn, Hg and Pb in the samples of non-authentic areas were higher. This method is sample, accurate, repeatable and could be used to evaluate the quality of Achyranthis Bidentatae Radix.

Fractionation of silver isotopes in native silver explained by redox reactions

NASA Astrophysics Data System (ADS)

Mathur, Ryan; Arribas, Antonio; Megaw, Peter; Wilson, Marc; Stroup, Steven; Meyer-Arrivillaga, Danilo; Arribas, Isabel

2018-03-01

Scant data exist on the silver isotope composition of native silver specimens because of the relative newness of the technique. This study increases the published dataset by an order of magnitude and presents 80 silver new isotope analyses from native silver originating from a diverse set of worldwide deposits (8 deposit types, 33 mining districts in five continents). The measured isotopic range (defined as δ109Ag/107Ag in per mil units compared to NIST 978 Ag isotope standard) is +2.1 to -0.86‰ (2σ errors less than 0.015); with no apparent systematic correlations to date with deposit type or even within districts. Importantly, the data centering on 0‰ all come from high temperature hypogene/primary deposits whereas flanking and overlapping data represent secondary supergene deposits. To investigate the causes for the more fractionated values, several laboratory experiments involving oxidation of silver from natural specimens of Ag-rich sulfides and precipitation and adsorption of silver onto reagent grade MnO2 and FeOOH were conducted. Simple leach experiments demonstrate little Ag isotope fractionation occurred through oxidation of Ag from native Ag (Δsolution-native109Ag = 0.12‰). In contrast, significant fractionation occurred through precipitation of native Ag onto MnO2 (up to Δsolution-MnO2109Ag = 0.68‰, or 0.3amu). Adsorption of silver onto the MnO2 and FeOOH did not produce as large fractionation as precipitation (mean value of Δsolution-MnO2109Ag = 0.10‰). The most likely cause for the isotopic variations seen relates to redox effects such as the reduction of silver from Ag (I) to Ag° that occurs during precipitation onto the mineral surface. Since many Ag deposits have halos dominated by MnO2 and FeOOH phases, potential may exist for the silver isotope composition of ores and surrounding geochemical haloes to be used to better understand ore genesis and potential exploration applications. Aside from the Mn oxides, surface fluid silver isotope compositions might provide information about geochemical reactions relevant to both environmental and hydrometallurgical applications.

Broiler litter as a micronutrient source for cotton: concentrations in plant parts.

PubMed

Tewolde, H; Sistani, K R; Rowe, D E

2005-01-01

Analytically, poultry litter contains nearly all essential micronutrients but the extent of phytoavailability of these nutrients and whether cotton (Gossypium hirsutum L.) and other crop plants can receive adequate amounts of these nutrients from litter is not fully known. The objective of this research was to determine whether cotton receives sufficient amounts of Fe, Cu, Mn, and Zn from litter and estimate the efficiency of cotton in extracting these metal nutrients from litter in the absence of any other source of the micronutrients. The greenhouse research used plastic pots filled with approximately 11 kg of a 2:1 (v/v) sand to vermiculite growing mix. Cotton (cv. Stoneville 474) was grown in the pots fertilized with broiler litter at rates of 30, 60, 90, or 120 g pot(-1) in a factorial combination with four supplemental nutrient solution (NS) treatments. The nutrient solutions consisted of full Hoagland's nutrient solution (NS-full); a solution of the macronutrients N, P, K, Ca, and Mg (NS-macro); a solution of the micronutrients Fe, Zn, Mn, Cu, B, and Mo (NS-micro); and water (NS-none). Based on tissue nutrient analysis, a one-time broiler litter application supplied adequate amounts of Fe, Cu, and Mn to bring the concentration of these nutrients in upper leaves within published sufficiency ranges. Zinc, with <17 mg kg(-1) concentration in the upper leaves, was the only micronutrient below the established sufficiency range regardless of the rate of applied litter. Cotton extracted Fe and Mn more efficiently than Cu or Zn, removing as much as 8.8% of Fe and 7.2% of Mn supplied by 30 g litter pot(-1). In contrast, the extraction efficiency was 1.7% for Cu and 1.9% for Zn. Roots accumulated 58% of the total absorbed Fe and 64% of Cu, and leaves accumulated 32% of the Fe and only 13% of the Cu supplied by litter. In contrast, only 16% of the total absorbed Mn and 23% of Zn accumulated in roots while leaves accumulated 64% of the total Mn and 37% of Zn. These results demonstrate that broiler litter is a valuable source of the metal nutrients supplying Fe, Cu, and Mn in full and Zn in part, but a very large fraction of the litter-supplied metal nutrients remained in the growing mix.

Structural, optical and photovoltaic properties of P3HT and Mn-doped CdS quantum dots based bulk hetrojunction hybrid layers

NASA Astrophysics Data System (ADS)

Jabeen, Uzma; Adhikari, Tham; Pathak, Dinesh; Shah, Syed Mujtaba; Nunzi, Jean-Michel

2018-04-01

Cadmium sulphide (CdS) and Mn-doped CdS nanocrystals were synthesized by co-precipitation method. The nanocrystals were characterized by Fluorescence, Fourier Transformed Infra-red Spectrometer (FTIR), UV-Visible, X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), Field Emission Scanning Electron Microscope (FESEM), and High Resolution Transmission Electron Microscope (HRTEM). A considerable blue shift of absorption band with respect to the cadmium sulphide was observed by the Mn concentration (0.5 M) in the doped sample with decreasing the size of nanocrystals. Other reason for this may be Mn doping. Subsequently the band gap was altered from 2.11 to 2.21 eV due to quantum confinement effect. Scanning electron microscope supplemented with EDAX was operated to find grain size and chemical composition of the synthesized nanomaterials. The PL spectrum of Mn-doped CdS nanocrystals displays three PL bands the first one, within the range of 500 nm and the second band at 537 nm, and the third one around 713 nm is labelled red band emission due to attributed to a 4T1→6A1 transition within the 3d shell of divalent manganese. XRD analysis showed that the material was in cubic crystalline state. A comparative study of surfaces of un-doped and metal doped CdS nanocrystals were investigated using X-ray Photoelectron Spectroscopy (XPS). The synthesized nanomaterial in combination with polymer, poly (3-hexyl thiophene) was operated in the construction of photovoltaic cells. The photovoltaic devices with CdS nanocrystals exhibited power conversion efficiency of 0.34% without annealing and 0.38% with annealing. However, the power conversion efficiency was enhanced by a factor of 0.35 without annealing and 0.42 with annealing with corporation of Mn impurity in CdS lattice. Atomic Force Microscopy was employed for morphology and packing behavior of blend of nanocrystals with organic polymer.

Removal and Recovery of Toxic Silver Ion Using Deep-Sea Bacterial Generated Biogenic Manganese Oxides

PubMed Central

Pei, Yuanjun; Chen, Xiao; Xiong, Dandan; Liao, Shuijiao; Wang, Gejiao

2013-01-01

Products containing silver ion (Ag+) are widely used, leading to a large amount of Ag+-containing waste. The deep-sea manganese-oxidizing bacterium Marinobacter sp. MnI7-9 efficiently oxidizes Mn2+ to generate biogenic Mn oxide (BMO). The potential of BMO for recovering metal ions by adsorption has been investigated for some ions but not for Ag+. The main aim of this study was to develop effective methods for adsorbing and recovering Ag using BMO produced by Marinobacter sp. MnI7-9. In addition, the adsorption mechanism was determined using X-ray photoelectron spectroscopy analysis, specific surface area analysis, adsorption kinetics and thermodynamics. The results showed that BMO had a higher adsorption capacity for Ag+ compared to the chemical synthesized MnO2 (CMO). The isothermal absorption curves of BMO and CMO both fit the Langmuir model well and the maximum adsorption capacities at 28°C were 8.097 mmol/g and 0.787 mmol/g, for BMO and CMO, respectively. The change in enthalpy (ΔHθ) for BMO was 59.69 kJ/mol indicating that it acts primarily by chemical adsorption. The change in free energy (ΔGθ) for BMO was negative, which suggests that the adsorption occurs spontaneously. Ag+ adsorption by BMO was driven by entropy based on the positive ΔSθ values. The Ag+ adsorption kinetics by BMO fit the pseudo-second order model and the apparent activation energy of Ea is 21.72 kJ/mol. X-ray photoelectron spectroscopy analysis showed that 15.29% Ag+ adsorbed by BMO was transferred to Ag(0) and meant that redox reaction had happened during the adsorption. Desorption using nitric acid and Na2S completely recovered the Ag. The results show that BMO produced by strain MnI7-9 has potential for bioremediation and reutilization of Ag+-containing waste. PMID:24312566

Exposure to phthalates and bisphenol A are associated with atopic dermatitis symptoms in children: a time-series analysis.

PubMed

Kim, Eun-Hye; Jeon, Byoung-Hak; Kim, Jihyun; Kim, Young-Min; Han, Youngshin; Ahn, Kangmo; Cheong, Hae-Kwan

2017-03-09

Despite increasing evidence on the relationship between exposure to phthalates and bisphenol A with allergies and asthma, reports on atopic dermatitis (AD) with these chemicals are few. We assessed the association between AD symptoms and the exposure to phthalates and bisphenol A and in children. We surveyed 18 boys with AD (age 3-7 years) in a day care center in Seoul between May 2009 and April 2010. AD symptoms were recorded by using a daily symptom diary. We collected 460 series of pooled urine twice a day, in the morning and afternoon, over 230 working days and measured the concentrations of mono-2-ethyl-5-oxohexyl phthalate (5-oxo-MEHP), mono-2-ethyl-5-hydroxyhexyl phthalate (5-OH-MEHP), mono-isobutyl phthalate (MnBP) and bisphenol A glucuronide (BPAG) in the pooled urine. Logistic regression was used for statistical analysis. Most phthalate metabolite levels were higher in the morning than in the afternoon (p < 0.0001). There was seasonal variation in the levels of phthalates and bisphenol A metabolites. Levels of 5-OH-MEHP, MnBP, and BPAG were highest in summer (p < 0.0001). Manifestation of AD symptoms was associated with an increase in urinary levels of MnBP (adjusted odds ratio, aOR = 2.85, 95% CI: 1.12-7.26 per 1 μg/L of MnBP) and BPAG (aOR = 1.79, 95% CI: 0.91-3.52 per 1 μg/L BPAG) on the same day. The levels of MnBP and BPAG in the previous day increased AD symptoms (aOR = 2.74, 95% CI: 1.21-6.20, for 1 μg/L of MnBP and aOR = 2.01, 95% CI: 1.08-3.74 for 1 μg/L BPAG). Our results suggest that exposure to phthalates and bisphenol A is associated with aggravation of AD symptoms in children.

Relation between Direct Observation of Relaxation and Self-Reported Mindfulness and Relaxation States

ERIC Educational Resources Information Center

Hites, Lacey S.; Lundervold, Duane A.

2013-01-01

Forty-four individuals, 18-47 (MN 21.8, SD 5.63) years of age, took part in a study examining the magnitude and direction of the relationship between self-report and direct observation measures of relaxation and mindfulness. The Behavioral Relaxation Scale (BRS), a valid direct observation measure of relaxation, was used to assess relaxed behavior…

Trace elements geochemistry of fractured basement aquifer in southern Malawi: A case of Blantyre rural

NASA Astrophysics Data System (ADS)

Mapoma, Harold Wilson Tumwitike; Xie, Xianjun; Nyirenda, Mathews Tananga; Zhang, Liping; Kaonga, Chikumbusko Chiziwa; Mbewe, Rex

2017-07-01

In this study, twenty one (21) trace elements in the basement complex groundwater of Blantyre district, Malawi were analyzed. The majority of the analyzed trace elements in the water were within the standards set by World Health Organization (WHO) and Malawi Standards Board (MSB). But, iron (Fe) (BH16 and 21), manganese (Mn) (BH01) and selenium (Se) (BH02, 13, 18, 19 and 20) were higher than the WHO and MSB standards. Factor analysis (FA) revealed up to five significant factors which accounted for 87.4% of the variance. Factor 1, 2 and 3 suggest evaporite dissolution and silicate weathering processes while the fourth factor may explain carbonate dissolution and pH influence on trace element geochemistry of the studied groundwater samples. According to PHREEQC computed saturation indices, dissolution, precipitation and rock-water-interaction control the levels of trace elements in this aquifer. Elevated concentrations of Fe, Mn and Se in certain boreholes are due to the geology of the aquifer and probable redox status of groundwater. From PHREEQC speciation results, variations in trace element species were observed. Based on this study, boreholes need constant monitoring and assessment for human consumption to avoid health related issues.

Evolution of the structure and mechanical properties of sheets of the Al-4.7Mg-0.32Mn-0.21Sc-0.09Zr alloy due to deformation accumulated upon rolling

NASA Astrophysics Data System (ADS)

Zolotorevskiy, V. S.; Dobrojinskaja, R. I.; Cheverikin, V. V.; Khamnagdaeva, E. A.; Pozdniakov, A. V.; Levchenko, V. S.; Besogonova, E. S.

2016-11-01

The mechanical properties and microstructure of sheets of an Al-4.7Mg-0.32Mn-0.21Sc-0.09Zr alloy deformed and annealed after rolling have been investigated. The total accumulated true strain was ɛf = 3.33-5.63, and the true strain at room temperature and at 200 °C was ɛc = 0.25-2.3. The strength properties of the sheets (yield stress σ0.2 = 495 MPa and ultimate tensile strength σu = 525 MPa) in the deformed state were greater than those after equal-channel angular pressing (ECAP) deformation. The mechanical properties of the deformed sheets after annealing depended on the size of subgrains inside the deformed grains bands with high-angle grain boundaries (HABs). With the increase in the annealing temperature from 150 to 300°C, the subgrain size increased from 80 to 300 nm. The relative elongation δ in the as-cast state and after annealing at 200-250°C (δ = 40-50%) was higher than that after annealing at 300-370°C (δ = 24-29%).

Siderophore-mediated oxidation of Ce and fractionation of HREE by Mn (hydr)oxide-coprecipitation and sorption on MnO2: Experimental evidence for negative Ce-anomalies in abiogenic manganese precipitates

NASA Astrophysics Data System (ADS)

Krämer, Dennis; Tepe, Nathalie; Bau, Michael

2014-05-01

We conducted experiments with Rare Earths and Yttrium (REY), where the REY were sorbed on synthetic manganese dioxide as well as on coprecipitating manganese (hydr)oxide in the presence and absence of the siderophore desferrioxamine-B (DFOB). Siderophores are a group of globally abundant biogenic complexing agents which are excreted by plants and bacteria to enhance the bioavailability of Fe in oxic environments. The model siderophore used in this study, DFOB, is a hydroxamate siderophore occurring in almost all environmental settings with concentrations in the nanomolar to millimolar range and is one of the most thoroughly studied siderophores. In the absence of siderophores and other organic ligands, trivalent Ce is usually surface-oxidized to tetravalent Ce during sorption onto manganese (hydr)oxides. Such Mn precipitates, therefore, often show positive Ce anomalies, whereas the ambient solutions exhibit negative Ce anomalies (Ohta and Kawabe, 2001). In marked contrast, however, REY sorption in the presence of DFOB produces negative Ce anomalies in the Mn precipitates and a distinct and characteristic positive Ce anomaly in the residual siderophore-bearing solution. Furthermore, the heavy REY with ionic radii larger than the radius of Sm are also almost completely prevented from sorption onto the Mn solid phases. Sorption of REY onto Mn (hydr)oxides in the presence of DFOB creates a distinct and pronounced fractionation of Ce and the heavy REY from the light and middle REY. Apart from Ce, which is oxidized in solution by the siderophore, the distribution of the other REY mimics the stability constants for multi-dentate complexes of REY with DFOB, as determined by Christenson & Schijf (2011). Heavier REY are forming stronger complexes (and are hence better "protected" from sorption) than light REY, excluding Ce. Preferential partitioning of Ce into the liquid phase during the precipitation of Mn (hydr)oxides has only rarely been described for natural Mn (hydr)oxides (e.g., Tanaka et al., 2010, Loges et al., 2012). Our experimental results demonstrate that biogenic organic ligands such as hydroxamate siderophores, may produce solutions with positive Ce anomaly (Bau et al., 2013) and may even counteract the surface oxidation of Ce on Mn (hydr)oxides. References Bau, M., Tepe, N., Mohwinkel, D., 2013. Siderophore-promoted transfer of rare earth elements and iron from volcanic ash into glacial meltwater, river and ocean water. Earth Planet. Sci. Lett. 364, 30-36. Christenson E. A. and Schijf J. (2011) Stability of YREE complexes with the trihydroxamate siderophore desferrioxamine B at seawater ionic strength. Geochim. Cosmochim. Acta 75, 7047-7062. Loges, A., Wagner, T., Barth, M., Bau, M., Göb, S., and Markl, G. 2012. Negative Ce anomalies in Mn oxides: The role of Ce4+ mobility during water-mineral interaction. Geochimica and Cosmochimica Acta 86, 296-317 Ohta A. and Kawabe I. (2001) REE (III) adsorption onto Mn dioxide (delta-MnO2) and Fe oxyhydroxide: Ce(III) oxidation by delta-MnO2. Geochim. Cosmochim. Acta 65, 695-703. Tanaka K., Tani Y., Takahashi Y., Tanimizu M., Suzuki Y., Kozai N. and Ohnuki T. (2010) A specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp. strain KR21-2. Geochim. Cosmochim. Acta 74, 5463-5477.

Time constraints on post-rift evolution of the Southwest Indian passive margin from ^{40}Ar-^{39Ar dating of supergene K-Mn oxides

NASA Astrophysics Data System (ADS)

Bonnet, Nicolas; Arnaud, Nicolas; Beauvais, Anicet; Chardon, Dominique

2013-04-01

The high-elevation passive margin of Southwest India is marked by the Western Ghats escarpment, which separates the coastal domain from the low-relief East-dipping Mysore plateau. The escarpment has evolved from the Seychelles rifting at ~ 63 Ma following the Deccan traps volcanic event at ~ 65-63 Ma. This escarpment results from differential erosion processes across the passive margin, the rate and timing of which depend upon whether the margin has evolved according to a model of downwarped or rising flank topography. We explore the post-rift evolution of the South Indian passive margin through the characterisation of stepped relicts of lateritic paleosurfaces across that margin, and notably by 40Ar-39Ar dating of in-situ formed K-Mn oxides in supergene Mn-ore deposits carried by these paleosurfaces. The genesis and maturation of Mn-ore deposits are generally linked to progressive weathering processes of the paleosurfaces, which expose them. Dating of K-Mn oxides thus document the timing of these processes [1], and potentially the ages of the altered paleosurface. Moreover, the elevation differences between successive lateritic paleosurfaces of different ages may provide denudation rates for the considered time spans. Previous work (e.g., [2]) and our own field investigations, allow identifying three main lateritic paleosurfaces on the plateau at altitude ranges of 1000-900 m (S2), 900-800 m (S3) and 800-700 m (S3d), and a lower paleosurface in the coastal domain at 150-50 m (S4). K-Mn oxides (cryptomelane) were sampled in Mn ore deposits from different paleosurfaces, particularly in the coastal area around Goa on S4 and in Sandur and Shimoga Mn-ore deposits exposed on S2 and S3. The 40Ar-39Ar ages obtained from carefully characterised mineralogical assemblages range from ~ 26 to ~ 36 Ma in the Sandur Mn-ore deposit indicating intense lateritic weathering processes at the Eocene-Oligocene transition underneath paleosurface S2. Similar ages of ~ 24 and ~ 32 Ma are obtained in two Shimoga Mn ore deposits carried by S3 and S2, respectively. A younger age (~ 21 Ma) is also obtained in a Goa deposit carried by S4. These first results suggest that the Western Ghats passive margin escarpment was established at the latest by early Miocene and that at least part of the inland Mysore plateau morphogenesis was achieved at that time. [1] Beauvais A. et al., Journal of Geophysical Research 113, F04007, 2008. [2] Gunnell, Y., Basin Research 10, 281-310, 1998.

High specificity of spot urinary free metanephrines in diagnosis and prognosis of pheochromocytomas and paragangliomas by HPLC with electrochemical detection.

PubMed

Zuo, Ming; Zhen, Qianna; Zhang, Xiaoqing; Zou, Wenbi; Yang, Xiangchun; Tian, Gang; Shi, Zhenghu; Li, Qifu; Ding, Min

2018-03-01

The metanephrines (MNs) in plasma and urine were proposed as biomarkers for the diagnosis of pheochromocytomas and paragangliomas (PPGLs). However, plasma free MNs and 24h urinary fractionated MNs were not satisfactory enough in specificity for the diagnosis of PPGLs. Moreover, the collection of 24h urine was inconvenient. This work examined the diagnostic and prognostic efficiency of free MNs in spot urine for PPGLs. We measured free MNs concentration in spot urine and plasma of 28 PPGLs patients and 155 control subjects by HPLC with electrochemical detection. Postoperative free MNs levels in spot urine and plasma of 14 PPGLs patients were also determined. Creatinine (Cr) concentration was used for the correction of urine volume. The specificity of spot urinary free MNs/Cr in the diagnosis of PPGLs was significantly higher than that of plasma free MNs [normetanephrine (NMN), 98.7% (95.4%-99.8%) vs 93.0% (87.4%-96.6%); metanephrine (MN), 93.6% (88.5%-96.9%) vs 84.5% (77.5%-90.0%)]. Meanwhile, the positive likelihood ratios for spot urinary free NMN/Cr and MN/Cr were 69.21 and 13.29, compared with 12.68 and 5.30 for plasma free NMN and MN, respectively. For the PPGLs patients underwent surgery, the plasma free MNs level appeared an abnormal elevation and yielded false-positive results for some patients. Our findings were validated in an independent cohort, resulting in the specificity of 100% for both urinary free NMN/Cr and MN/Cr, and 97.3% and 83.8% for plasma free NMN and MN, respectively. Spot urinary free MNs/Cr, superior to plasma free MNs, presented a promising biomarker for the diagnosis and prognosis of PPGLs. Copyright © 2017 Elsevier B.V. All rights reserved.

Over-expression of copper/zinc superoxide dismutase in the median preoptic nucleus attenuates chronic angiotensin II-induced hypertension in the rat.

PubMed

Collister, John P; Bellrichard, Mitch; Drebes, Donna; Nahey, David; Tian, Jun; Zimmerman, Matthew C

2014-12-02

The brain senses circulating levels of angiotensin II (AngII) via circumventricular organs, such as the subfornical organ (SFO), and is thought to adjust sympathetic nervous system output accordingly via this neuro-hormonal communication. However, the cellular signaling mechanisms involved in these communications remain to be fully understood. Previous lesion studies of either the SFO, or the downstream median preoptic nucleus (MnPO) have shown a diminution of the hypertensive effects of chronic AngII, without providing a clear explanation as to the intracellular signaling pathway(s) involved. Additional studies have reported that over-expressing copper/zinc superoxide dismutase (CuZnSOD), an intracellular superoxide (O2·-) scavenging enzyme, in the SFO attenuates chronic AngII-induced hypertension. Herein, we tested the hypothesis that overproduction of O2·- in the MnPO is an underlying mechanism in the long-term hypertensive effects of chronic AngII. Adenoviral vectors encoding human CuZnSOD (AdCuZnSOD) or control vector (AdEmpty) were injected directly into the MnPO of rats implanted with aortic telemetric transmitters for recording of arterial pressure. After a 3 day control period of saline infusion, rats were intravenously infused with AngII (10 ng/kg/min) for ten days. Rats over-expressing CuZnSOD (n = 7) in the MnPO had a blood pressure increase of only 6 ± 2 mmHg after ten days of AngII infusion while blood pressure increased 21 ± 4 mmHg in AdEmpty-infected rats (n = 9). These results support the hypothesis that production of O2·- in the MnPO contributes to the development of chronic AngII-dependent hypertension.

Gamma Radiation Induces Micronucleated Reticulocytes in 3-D Bone Marrow Bioreactors in Vitro

PubMed Central

Sun, Hongliang; Dertinger, Stephen D.; Hyrien, Ollivier; David Wu, J. H.; Chen, Yuhchyau

2009-01-01

Radiation injury to the bone marrow is potentially lethal due to the potent DNA-damaging effects on cells of the hematopoietic system, including bone marrow stem cell, progenitor, and the precursor cell populations. Investigation of radiation genotoxic effects on bone marrow progenitor/precursor cells has been challenged by the lack of optimal in vitro surrogate organ culture systems, and the overall difficulty to sustain lineage-specific proliferation and differentiation of hematopoiesis in vitro. We report the investigation of radiation genotoxic effects in bone marrow cultures of C57Bl/6 mice established in 3-D bioreactors, which sustain long-term bone marrow cultures. For these studies, genotoxicity is measured by the induction of micronucleated reticulocytes (MN-RET). The kinetics and dose-response relationship of MN-RET induction in response to gamma-radiation of bioreactor-maintained bone marrow cultures are presented. Our data showed that 3-D long-term bone marrow cultures had sustained erythropoiesis capable of generating reticulocytes up to 8 weeks. The peak time-interval of viable cell output and percentage of reticulocytes increased steadily and reached the initial peak between the 14th to 21st days after inoculations. This was followed by a rebound or staying relatively constant until week 8. The percentage of MN-RET reached the maximum between 24 and 32 hours post 1 Gy gamma-ray. There was a near linear MN-RET induction by gamma radiation from 0 Gy to 1.0 Gy, followed by an attenuated increase to 1.5 – 2.0 Gy. The MN-RET response showed a downtrend beyond 2 Gy. Our data suggest that bone marrow culture in the 3-D bioreactor may be a useful organ culture system for the investigation of radiation genotoxic effect in vitro. PMID:19786117

Influence of Bulk Chemical Composition on Relative Sensitivity Factors for 55Mn/52Cr by SIMS: Implications for the 53Mn-53Cr Chronometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matzel, J; Jacobsen, B; Hutcheon, I D

2009-09-09

The {sup 53}Mn-{sup 53}Cr systematics of meteorite samples provide an important high resolution chronometer for early solar system events. Accurate determination of the initial abundance of {sup 53}Mn ({tau}{sub 1/2} = 3.7 Ma) by secondary ion mass spectrometry (SIMS) is dependent on properly correcting for differing ion yields between Mn and Cr by use of a relative sensitivity factor (RSF). Ideal standards for SIMS analysis should be compositionally and structurally similar to the sample of interest. However, previously published Mn-Cr studies rely on few standards (e.g., San Carlos olivine, NIST 610 glass) despite significant variations in chemical composition. We investigatemore » a potential correlation between RSF and bulk chemical composition by determining RSFs for {sup 55}Mn/{sup 52}Cr in 11 silicate glass and mineral standards (San Carlos olivine, Mainz glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, BM90/21-G, and T1-G, NIST 610 glass, and three LLNL pyroxene-composition glasses). All standards were measured on the Cameca ims-3f ion microprobe at LLNL, and a subset were also measured on the Cameca ims-1270 ion microprobe at the Geological Survey of Japan. The standards cover a range of bulk chemical compositions with SiO{sub 2} contents of 40-71 wt.%, FeO contents of 0.05-20 wt.% and Mn/Cr ratios between 0.4 and 58. We obtained RSF values ranging from 0.83 to 1.15. The data obtained on the ims-1270 ion microprobe are within {approx}10% of the RSF values obtained on the ims-3f ion microprobe, and the RSF determined for San Carlos olivine (0.86) is in good agreement with previously published data. The typical approach to calculating an RSF from multiple standard measurements involves making a linear fit to measured {sup 55}Mn/{sup 52}Cr versus true {sup 55}Mn/{sup 52}Cr. This approach may be satisfactory for materials of similar composition, but fails when compositions vary significantly. This is best illustrated by the {approx}30% change in RSF we see between glasses with similar Mn/Cr ratios but variable Fe and Na content. We are developing an approach that uses multivariate analysis to evaluate the importance of different chemical components in controlling the RSF and predict the RSF of unknowns when standards of appropriate composition are not available. Our analysis suggests that Fe, Si, and Na are key compositional factors in these silicate standards. The RSF is positively correlated with Fe and Si and negatively correlated with Na. Work is currently underway to extend this analysis to a wider range of chemical compositions and to evaluate the variability of RSF on measurements obtained by NanoSIMS.« less

Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balch, Dorian K.; Sofronis, Petros; Somerday, Brian P.

2005-03-01

The objective of this study was to quantify the hydrogen-assisted fracture susceptibility of gas-tungsten arc (GTA) welds in the nitrogen-strengthened, austenitic stainless steels 21Cr-6Ni-9Mn (21-6-9) and 22Cr-13Ni-5Mn (22-13-5). In addition, mechanisms of hydrogen-assisted fracture in the welds were identified using electron microscopy and finite-element modeling. Elastic-plastic fracture mechanics experiments were conducted on hydrogen-charged GTA welds at 25 C. Results showed that hydrogen dramatically lowered the fracture toughness from 412 kJ/m{sup 2} to 57 kJ/m{sup 2} in 21-6-9 welds and from 91 kJ/m{sup 2} to 26 kJ/m{sup 2} in 22-13-5 welds. Microscopy results suggested that hydrogen served two roles in themore » fracture of welds: it promoted the nucleation of microcracks along the dendritic structure and accelerated the link-up of microcracks by facilitating localized deformation. A continuum finite-element model was formulated to test the notion that hydrogen could facilitate localized deformation in the ligament between microcracks. On the assumption that hydrogen decreased local flow stress in accordance with the hydrogen-enhanced dislocation mobility argument, the finite-element results showed that deformation was localized in a narrow band between two parallel, overlapping microcracks. In contrast, in the absence of hydrogen, the finite-element results showed that deformation between microcracks was more uniformly distributed.« less

Test Review: Wiig, E H., Semel, E., Secord, W. A. (2013) Clinical Evaluation of Language Fundamentals-Fifth Edition (CELF-5). Bloomington, MN: NCS Pearson

ERIC Educational Resources Information Center

Coret, Marian C.; McCrimmon, Adam W.

2015-01-01

The "Clinical Evaluation of Language Fundamentals-Fifth Edition" (CELF-5; Wiig, Semel, & Secord, 2013) is a recently updated battery of tests designed to assess, diagnose, and measure changes in language and communication in individuals 5 to 21 years of age. Designed to identify language strengths and weaknesses, determine service…

Age and Influenza-Specific Pre-Vaccination Antibodies Strongly Affect Influenza Vaccine Responses in the Icelandic Population whereas Disease and Medication Have Small Effects

PubMed Central

Olafsdottir, Thorunn A.; Alexandersson, Kristjan F.; Sveinbjornsson, Gardar; Lapini, Giulia; Palladino, Laura; Montomoli, Emanuele; Del Giudice, Giuseppe; Gudbjartsson, Daniel F.; Jonsdottir, Ingileif

2018-01-01

Influenza vaccination remains the best strategy for the prevention of influenza virus-related disease and reduction of disease severity and mortality. However, there is large individual variation in influenza vaccine responses. In this study, we investigated the effects of gender, age, underlying diseases, and medication on vaccine responses in 1,852 Icelanders of broad age range who received trivalent inactivated influenza virus vaccination in 2012, 2013, or 2015. Hemagglutination inhibition (HAI) and microneutralization (MN) titers were measured in pre- and post-vaccination sera. Of the variables tested, the strongest association was with level of pre-vaccination titer that explained a major part of the variance observed in post-vaccination titers, ranging from 19 to 29%, and from 7 to 21% in fold change (FC), depending on the strain and serological (HAI or MN) analysis performed. Thus, increasing pre-vaccination titer associated with decreasing FC (P = 1.1 × 10−99–8.6 × 10−30) and increasing post-vaccination titer (P = 2.1 × 10−159–1.1 × 10−123). Questionnaires completed by 87% of the participants revealed that post-vaccination HAI titer showed association with repeated previous influenza vaccinations. Gender had no effect on vaccine response whereas age had a strong effect and explained 1.6–3.1% of HAI post-vaccination titer variance and 3.1% of H1N1 MN titer variance. Vaccine response, both fold increase and seroprotection rate (percentage of individuals reaching HAI ≥ 40 or MN ≥ 20), was higher in vaccinees ≤37 years of age (YoA) than all other age groups. Furthermore, a reduction was observed in the H1N1 MN titer in people ≥63 YoA, demonstrating a decreased neutralizing functionality of vaccine-induced antibodies at older age. We tested the effects of underlying autoimmune diseases, asthma and allergic diseases and did not observe significant associations with vaccine responses. Intake of immune modulating medication did not show any association. Taken together, our results show that previous encounter of influenza vaccination or infection, reflected in high HAI and MN pre-vaccination titer has the strongest negative effect on vaccine responses measured as FC and the strongest positive effect on post-vaccination titer. Increasing age had also an effect but not gender, underlying disease or medication. PMID:29358933

The effect of low temperature thermal annealing on the magnetic properties of Heusler Ni-Mn-Sn melt-spun ribbons

NASA Astrophysics Data System (ADS)

Llamazares, J. L. Sánchez; Quintana-Nedelcos, A.; Ríos-Jara, D.; Sánchez-Valdes, C. F.; García-Fernández, T.; García, C.

2016-03-01

We report the effect of low temperature vacuum annealing (823 K; 550 °C) on the elemental chemical composition, structural phase transition temperatures, phase structure, and magnetic properties of Ni50.6Mn36.3Sn13.1 as-solidified ribbons. Their elemental chemical composition, highly oriented columnar-like microstructure and single-phase character (L21-type crystal structure for austenite) remain unchanged after this low temperature annealing. Annealed ribbons show a reduction of interatomic distances which lead to a small change in the characteristic phase transition temperatures ( 3-6 K) but to a significant rise of 73 and 63% in the saturation magnetization of the martensite and austenite phases, respectively, that can be strictly ascribed to the strengthening of ferromagnetic interactions due to the change in interatomic distances.

The relation between lattice parameters and very low twinning stress in Ni50Mn25+x Ga25-x magnetic shape memory alloys

NASA Astrophysics Data System (ADS)

Straka, L.; Drahokoupil, J.; Pacherová, O.; Fabiánová, K.; Kopecký, V.; Seiner, H.; Hänninen, H.; Heczko, O.

2016-02-01

In search of the origins of the extraordinary low twinning stress of Ni-Mn-Ga 10M martensite, we studied the temperature induced changes in lattice parameters of Ni50Mn25+x Ga25-x (x = 2.7-3.9) single crystal samples and compared them with twinning stress dependences. The alloys exhibited transformation to five-layered (10M) martensite structure (cubic to monoclinic) between 297 to 328 K and exhibited the magnetic shape memory effect in martensite. The structural changes were monitored using x-ray diffraction in the temperature range 200-343 K. The 10M structure was approximated by monoclinic lattice, a = b > c, γ > 90° with the coordinates derived from the cubic unit cell of the parent L21 phase. The lattice parameters γ and c/a correlate well with the universal linear increase of twinning stress of type 1 twins with decreasing temperature. On the contrary, the twinning stress is not affected by differences between a and b and thus a/b twins seem to play no role in a - c twin boundary motion resulting in magnetically induced reorientation.

Neutron diffraction study of the martensitic transformation and chemical order in Heusler alloy Ni 1.91Mn 1.29Ga 0.8

DOE PAGES

Ari-Gur, Pnina; Garlea, Vasile O.; Cao, Huibo; ...

2015-11-05

In this study, Heusler alloys of Ni-Mn-Ga compositions demonstrate ferromagnetic shape memory effect in the martensitic state. The transformation temperature and the chemical order depend strongly on the composition. In the current work, the structure and chemical order of the martensitic phase of Ni 1.91Mn 1.29Ga 0.8 were studied using neutron diffraction; the diffraction pattern was refined using the FullProf software. It was determined that the structural transition occurs around 330 K. At room temperature, 300 K, which is below the martensite transformation temperature, all the Bragg reflections can be described by a monoclinic lattice with a symmetry of spacemore » group P 1 2/m 1 and lattice constants of a = 4.23047(7) [Å], b = 5.58333(6) [Å], c = 21.0179(2) [Å], beta = 90.328(1). The chemical order is of critical importance in these alloys, and it was previously studied at 363 K. Analysis of the neutron diffraction in the monoclinic phase shows that the chemical order is maintained during the martensitic transformation.« less

[Association between genetic polymorphisms in pre-miR-146a and pre-miR-196a2 and genetic damage levels among coke oven workers].

PubMed

Wang, Tian; Deng, Qi-fei; Zhang, Xiao; Li, Xiao-liang; Deng, Si-yun; Dai, Xia-yun; Huang, Su-li; Feng, Jing; Li, Jun; Wu, Tang-chun; Guo, Huan

2013-08-01

To investigate the association of rs2910164 G > C polymorphism and rs11614913 T > C polymorphism in pre-miR-146a and pre-miR-196a2 with genetic damage levels in coke oven workers. A total of 575 nonsmoking workers who have worked for more than one year in a coke-oven plant at Wuhan, Hubei Province were enrolled in this study in September to October, 2010. The general characteristics as well as blood and urine samples were collected. The genetic damage levels were detected by cytokinesis-block micronucleus cytom assay and represented as micronucleus (MN) frequencies of binucleate cells in peripheral blood lymphocytes. The rs2910164 G > C polymorphisms in pre-miR-146a and rs11614913 T > C polymorphisms in pre-miR-196a2 were genotyped by using TaqMan assay. The plasma concentrations of benzo[a]pyrene-diolepoxide (BPDE)-albumin adducts were determined by using ELISA. All data were analyzed, the frequency ratio (FR) and 95%CI were calculated. Totally, 575 workers were taken into consideration. The rs2910164 C allele was associated with increased MN frequencies in the coke oven workers (P trend = 0.025), and the MN frequencies were higher in rs2910164 CC genotype carriers (4.38 ± 3.46) than in wild-type rs2910164 GG genotype carriers (4.02 ± 3.09) (FR = 1.18, 95%CI:1.04-1.34). The further stratified analyses by working years, gender, alcohol consumption, and the levels of BPDE-albumin adducts showed that the effects of rs2910164 C allele in increasing MN frequencies were robust in subjects who were males (FR = 1.11, 95%CI:1.02-1.20), nondrinkers (FR = 1.07, 95%CI:1.00-1.14), working years less than 20 (FR = 1.12, 95%CI:1.03-1.22), and workers with lower BPDE-albumin adducts levels (FR = 1.11, 95%CI:1.02-1.21) (P trend = 0.011, 0.044, 0.006 and 0.020, respectively). In addition, the MN frequencies were higher in workers with rs11614913 TC genotype (4.27 ± 2.91) than workers with rs11614913 TT genotype (3.90 ± 3.32) (FR = 1.12, 95%CI:1.02-1.23).Workers carried both rs2910164 GG and rs11614913 TT genotypes were set as a control, and the MN frequencies of workers with both rs2910164 CC and rs11614913 CC genotypes (5.32 ± 4.94) were 1.51 (1.21-1.89) times higher than the control (3.75 ± 3.01). The rs2910164 C allele in pre-miR-146a and rs11614913 C allele in pre-miR-196a2 were associated with increased genetic damage levels in coke oven workers.

A Hydrocarbon Fuel Flash Vaporization System for a Pulsed Detonation Engine

DTIC Science & Technology

2006-12-01

Experiments were performed in the Air Force Research Laboratory (AFRL) Pulsed Detonation Research Facility at Wright Patterson AFB, Ohio. The PDE ...AFRL-MN-EG-TP-2006-7420 A HYDROCARBON FUEL FLASH VAPORIZATION SYSTEM FOR A PULSED DETONATION ENGINE (PREPRINT) K. Colin Tucker...85,7<&/$66,),&$7,212) E7(/(3+21(180%(5 ,QFOXGHDUHDFRGH A Hydrocarbon Fuel Flash Vaporization System for a Pulsed Detonation Engine K

Missile Aerodynamics

DTIC Science & Technology

1988-01-01

considered preferable to inadequate treatment of more material. Readers frequently wonder what motivates the author in his arrange- ment of material. The...fins: M11, = Mn22 +~p’I (a2/sl)n/2]4"n - (2)21 in1, = 01*a rn13 = 0 ’n23 = 0 M33, =.533ps’ n =3 a =0 =n Ps4 n =4 a =0 7r . n=P8 n. fins H. Regular

Evaluation of the genetic alterations in direct and indirect exposures of hexavalent chromium [Cr(VI)] in leather tanning industry workers North Arcot District, South India.

PubMed

Balachandar, Vellingiri; Arun, Meyyazhagan; Mohana Devi, Subramaniam; Velmurugan, Palanivel; Manikantan, Pappusamy; Karthick Kumar, Alagamuthu; Sasikala, Keshavarao; Venkatesan, Chinnakulandai

2010-10-01

The focal aim of the present study was to identify the genetic alterations occurring in the tannery workers and surrounding inhabitants chronically exposed to hexavalent chromium [Cr(VI)]. A total of 108 samples which includes 72 exposed subjects [36 directly exposed (DE) subjects and 36 indirectly exposed (IE) subjects] and 36 controls were recruited for this study. The exposed subjects and controls were selected based on the Cr level present in air and their urine. Directly exposed subjects were categorized based on their work duration in the tannery industries, whereas the indirectly exposed subjects were categorized based on their year of residence in the place adjacent to tannery industries for more than 3 decades. Controls were normal and healthy. Age was matched for the exposed subjects and controls. The exposed subjects as well as the controls were categorized based on their age (group I, <40 years; group II, >41 years). Cell cultures were established from blood samples (5 ml from each subject) collected from the subjects (exposed subjects and controls) after obtaining informed consent. G-banding (Giemsa staining) of the cultures, micronucleus (MN) assay and comet assay were used to identify the genetic alterations of individuals exposed to Cr(VI) in comparison with the controls. A higher degree of total CA [12 ± 8.49 (21-25 years)] and MN [18.69 ± 7.39 (11-15 years)] was found in DE subjects compared to other groups. In IE subjects, elevated levels of CA [5.67 ± 1.15 (51-60 years)] and MN [25 ± 9.89 (71-80 years)] were observed. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to Cr exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P < 0.05 by ANOVA). The MN/1,000 binucleated cells were significantly increased (P < 0.05) in the peripheral lymphocytes of DE and IE subjects in comparison with controls. The mean tail length of comet assay for DE, IE and controls were analyzed. The mean tail length of DE subjects [4.21 (3.21-10.98)] was higher compared to that of IE subjects [3.98 (2.98-11.27)] and controls [3.01 (2.68-9.40)]. In conclusion, this work shows a clear genotoxic effect associated with chromium exposure, both directly and indirectly. Our result reinforces the higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. There is a strong need to educate those who work with potentially hazardous heavy about its adverse effects and highlight the importance of using protective measures.

Zincovelesite-6N6S, Zn3(Fe3+,Mn3+,Al,Ti)8O15(OH), a new högbomite-supergroup mineral from Jacupica mountains, Republic of Macedonia

NASA Astrophysics Data System (ADS)

Chukanov, Nikita V.; Krzhizhanovskaya, Maria G.; Jančev, Simeon; Pekov, Igor V.; Varlamov, Dmitry A.; Göttlicher, Jörg; Rusakov, Vyacheslav S.; Polekhovsky, Yury S.; Chervonnyi, Alexandr D.; Ermolaeva, Vera N.

2018-02-01

A new mineral species zincovelesite-6N6S with the simplified formula Zn3(Fe3+,Mn3+,Al,Ti)8O15(OH) was discovered in the orogenetic zone related to the "Mixed Series" metamorphic complex near the Nežilovo village, Jacupica Mountains, Pelagonia mountain range, Republic of Macedonia. In oxide Zn-Fe-Mn ore, zincovelesite-6N6S forms lenticular aggregates up to 2 × 2 × 0.5 mm consisting of thin near-coplanar platelets up to 70 × 70 × 1 µm3 and associated with franklinite, gahnite, hetaerolite, zincochromite, ferricoronadite, baryte, As-rich fluorapatite, dolomite, Zn-bearing talc, almeidaite, hydroxycalcioroméite, zircon, quartz, and scheelite. In silicate-baryte zones of the metasomatic rock, uniaxial intergrowths of zincovelesite-6N6S with nežilovite are observed. The new mineral is opaque, black, with brownish-black streak. The lustre is strong submetallic to metallic. The micro-indentation hardness is 1118 kg/mm2 which corresponds to Mohs' hardness ca. 6½. Zincovelesite-6N6S is brittle, with uneven fracture. No cleavage or parting is observed. The density calculated from the empirical formula is 5.158 g/cm3. In reflected light zincovelesite-6N6S is light grey. The reflectance values [R max/R min, % (λ, nm)] are: 17.1/13.4 (470), 16.5/12.8 (546), 16.2/12.6 (589), 15.6/12.2 (650). The IR spectrum shows the presence of OH groups. According to the Mössbauer spectrum, all iron is trivalent. The Mn K-edge XANES spectroscopy shows that Mn is predominantly or completely trivalent. The average chemical composition is (wt%; electron microprobe, H2O determined by gas chromatography of ignition products): MgO 0.97, CuO 0.50, ZnO 30.80, Al2O3 8.17, Mn2O3 21.31, Fe2O3 29.44, TiO2 5.28, Sb2O5 3.74, H2O 1.1, total 101.31. The empirical formula based on 16 O atoms is H1.05Zn3.26Mg0.21Cu0.05Fe3+ 3.18Mn3+ 2.32Al1.38Ti0.57Sb0.20O16. Zincovelesite-6N6S is trigonal, probable space group P-3m1, a = 5.902(2) Å, c = 55.86(1) Å, V = 1684.8(9) Å3, Z = 6. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 2.952 (62) (110), 2.881 (61) (1.0.16), 2.515 (100) (204), 2.493 (88) (1.1.12), 2.451 (39) (1.0.20), 1.690 (19) (304, 2.1.16), 1.572 (19) (2.0.28), 1.475 (29) (221). Zincovelesite-6N6S is the first Fe3+-dominant member of the högbomite supergroup and, thus, can be considered as a parent species of a new mineral group. The rootname velesite is given for the discovery locality near the city of Veles.

Effect of solution treatment on the microstructure, tensile properties, and corrosion behavior of the Mg-5Sn-2Zn-0.1Mn alloy

NASA Astrophysics Data System (ADS)

El Mahallawy, N.; Hammouda, R.; Shoeib, M.; Diaa, Alia A.

2018-01-01

Working on magnesium alloys containing relatively inexpensive alloying elements such as tin, zinc, and manganese have been a target for many studies. The binary Mg-Sn and Mg-Zn systems have a wide range of solid solubility which make them heat-treatable alloys. In the present study, the microstructure, tensile properties, and corrosion behavior of the Mg-5Sn-2Zn-0.1Mn alloy was studied in the as cast state and after heat treatment at a temperature reaching 450 °C for about 24 h. It was found that a noticeable enhancement in strength and corrosion resistance was achieved through heat treatment. The strength of the as cast alloy increased from 76.24 ± 6.21 MPa to 187.33 ± 10.3 MPa, while the corrosion rate decreased from 1.129 to 0.399 mm y-1.

Pseudosymmetric fac-di-aqua-trichlorido[(di-methyl-phosphor-yl)methanaminium-κO]manganese(II).

PubMed

Reiss, Guido J

2013-05-01

In the title compound, [Mn(C3H11NOP)Cl3(H2O)2], the Mn(II) metal center has a distorted o-cta-hedral geometry, coordinated by the three chloride ligands showing a facial arrangement. Two water mol-ecules and the O-coordinated dpmaH cation [dpmaH = (di-methyl-phosphor-yl)methanaminium] complete the coordination sphere. Each complex mol-ecule is connected to its neighbours by O-H⋯Cl and N-H⋯Cl hydrogen bonds. Two of the chloride ligands and the two water ligands form a hydrogen-bonded polymeric sheet in the ab plane. Furthermore, these planes are connected to adjacent planes by hydrogen bonds from the aminium function of cationic dpmaH ligand. A pseudo-mirror plane perpendicular to the b axis in the chiral space group P21 is observed together with inversion twinning [ratio = 0.864 (5):0.136 (5)].

Low-cost, high-strength Fe--Ni--Cr alloys for high temperature exhaust valve application

DOEpatents

Muralidharan, Govindarajan

2017-09-05

An Fe--Ni--Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.11.5, 0.53.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.65, and 0.16.ltoreq.Cr/(Fe+Ni+Cr+Mn).ltoreq.0.21, the alloy being essentially free of Cu, Si, and V.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beran, L.; Cejpek, P.; Kulda, M.

Optical and magneto-optical properties of single crystal of Ni{sub 50.1}Mn{sub 28.4}Ga{sub 21.5} magnetic shape memory alloy during its transformation from martensite to austenite phase were systematically studied. Crystal orientation was approximately along (100) planes of parent cubic austenite. X-ray reciprocal mapping confirmed modulated 10 M martensite phase. Temperature depended measurements of saturation magnetization revealed the martensitic transformation at 335 K during heating. Magneto-optical spectroscopy and spectroscopic ellipsometry were measured in the sample temperature range from 297 to 373 K and photon energy range from 1.2 to 6.5 eV. Magneto-optical spectra of polar Kerr rotation as well as the spectra of ellipsometric parameter Ψ exhibitedmore » significant changes when crossing the transformation temperature. These changes were assigned to different optical properties of Ni-Mn-Ga in martensite and austenite phases due to modification of electronic structure near the Fermi energy during martensitic transformation.« less

Contactless electroreflectance study of strained Zn0.79Cd0.21Se/ZnSe double quantum wells

NASA Astrophysics Data System (ADS)

Tu, R. C.; Su, Y. K.; Lin, D. Y.; Li, C. F.; Huang, Y. S.; Lan, W. H.; Tu, S. L.; Chang, S. J.; Chou, S. C.; Chou, W. C.

1998-01-01

We have studied various excitonic transitions of strained Zn0.79Cd0.21Se/ZnSe double quantum wells, grown by molecular beam epitaxy on (100) GaAs substrates, using contactless electroreflectance (CER) at 15 and 300 K. A number of intersub-band transitions in the CER spectra from the sample have been observed. An analysis of the CER spectra has led to the identification of various excitonic transitions, mnH(L), between the mth conduction band state and the nth heavy (light)-hole band state. The conduction-band offset Qc is used as an adjustable parameter to study the band offset in the strained Zn0.79Cd0.21Se/ZnSe system. The value of Qc is determined to be 0.67±0.03.

ABTS as an Electron Shuttle to Enhance the Oxidation Kinetics of Substituted Phenols by Aqueous Permanganate.

PubMed

Song, Yang; Jiang, Jin; Ma, Jun; Pang, Su-Yan; Liu, Yong-Ze; Yang, Yi; Luo, Cong-Wei; Zhang, Jian-Qiao; Gu, Jia; Qin, Wen

2015-10-06

In this study, it was, interestingly, found that 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS), a widely used electron shuttle, could greatly accelerate the oxidation of substituted phenols by potassium permanganate (Mn(VII)) in aqueous solutions at pH 5-9. This was attributed to the fact that these substituted phenols could be readily oxidized by the stable radical cation (ABTS(•+)), which was quickly produced from the oxidation of ABTS by Mn(VII). The reaction of Mn(VII) with ABTS exhibited second-order kinetics, with stoichiometries of ∼5:1 at pH 5-6 and ∼3:1 at pH 7-9, and the rate constants varied negligibly from pH 5 to 9 (k = (9.44 ± 0.21) × 10(4) M(-1) s(-1)). Comparatively, the reaction of ABTS(•+) with phenol showed biphasic kinetics. The second-order rate constants for the reactions of ABTS(•+) with substituted phenols obtained in the initial phase were strongly affected by pH, and they were several orders of magnitude higher than those for the reactions of Mn(VII) with substituted phenols at each pH. Good Hammett-type correlations were found for the reactions of ABTS(•+) with undissociated (log(k) = 2.82-4.31σ) and dissociated phenols (log(k) = 7.29-5.90σ). The stoichiometries of (2.2 ± 0.06):1 (ABTS(•+) in excess) and (1.38 ± 0.18):1 (phenol in excess) were achieved in the reaction of ABTS(•+) with phenol, but they exhibited no pH dependency.

The cytokinesis-blocked micronucleus assay: dose-response calibration curve, background frequency in the population and dose estimation.

PubMed

Rastkhah, E; Zakeri, F; Ghoranneviss, M; Rajabpour, M R; Farshidpour, M R; Mianji, F; Bayat, M

2016-03-01

An in vitro study of the dose responses of human peripheral blood lymphocytes was conducted with the aim of creating calibrated dose-response curves for biodosimetry measuring up to 4 Gy (0.25-4 Gy) of gamma radiation. The cytokinesis-blocked micronucleus (CBMN) assay was employed to obtain the frequencies of micronuclei (MN) per binucleated cell in blood samples from 16 healthy donors (eight males and eight females) in two age ranges of 20-34 and 35-50 years. The data were used to construct the calibration curves for men and women in two age groups, separately. An increase in micronuclei yield with the dose in a linear-quadratic way was observed in all groups. To verify the applicability of the constructed calibration curve, MN yields were measured in peripheral blood lymphocytes of two real overexposed subjects and three irradiated samples with unknown dose, and the results were compared with dose values obtained from measuring dicentric chromosomes. The comparison of the results obtained by the two techniques indicated a good agreement between dose estimates. The average baseline frequency of MN for the 130 healthy non-exposed donors (77 men and 55 women, 20-60 years old divided into four age groups) ranged from 6 to 21 micronuclei per 1000 binucleated cells. Baseline MN frequencies were higher for women and for the older age group. The results presented in this study point out that the CBMN assay is a reliable, easier and valuable alternative method for biological dosimetry.

Effectiveness of Preacclimatization Strategies for High-Altitude Exposure

DTIC Science & Technology

2013-01-01

pulse oximeter (Model 8600, Nonin Medical, Inc., Plymouth, MN). Ventilatory assessments were conducted repeatedly during all phases of each study...progressive rise in arterial oxygen saturation (Sa02, mean ± SE) for 37 men (21) and 22 women (20) while living on the summit of Pikes Peak (4300 m). Men...almost immediately with altitude exposure to compensate for the lower partial pressure of oxygen (P02 ). Nevertheless, the first few days of

Investigation of Sorption Mass Transfer Models Using Synthetic Soils

DTIC Science & Technology

1996-12-01

Goltz for his useful comments regarding my review of the literature. His comments served to enhance the readability of my review as well as the...versions. Researchers ( Goltz , 1986; Wu and Gschwend, 1986; Ball and Roberts, 1991b; Young and Ball, 1995) have applied Fick’s second law of diffusion...Values," Environmental Science and Technology, Vol. 21, pp. 243-248, 1987. Goltz , M.N., Three-Dimensional Analytical Modeling of Diffusion-limited

Magnetocaloric effect in potassium doped lanthanum manganite perovskites prepared by a pyrophoric method

NASA Astrophysics Data System (ADS)

Das, Soma; Dey, T. K.

2006-08-01

The magnetocaloric effect (MCE) in fine grained perovskite manganites of the type La1-xKxMnO3 (0

Development of TRIP-Aided Lean Duplex Stainless Steel by Twin-Roll Strip Casting and Its Deformation Mechanism

NASA Astrophysics Data System (ADS)

Zhao, Yan; Zhang, Weina; Liu, Xin; Liu, Zhenyu; Wang, Guodong

2016-12-01

In the present work, twin-roll strip casting was carried out to fabricate thin strip of a Mn-N alloyed lean duplex stainless steel with the composition of Fe-19Cr-6Mn-0.4N, in which internal pore defects had been effectively avoided as compared to conventional cast ingots. The solidification structure observed by optical microscope indicated that fine Widmannstatten structure and coarse-equiaxed crystals had been formed in the surface and center, respectively, with no columnar crystal structures through the surface to center of the cast strip. By applying hot rolling and cold rolling, thin sheets with the thickness of 0.5 mm were fabricated from the cast strips, and no edge cracks were formed during the rolling processes. With an annealing treatment at 1323 K (1050 °C) for 5 minutes after cold rolling, the volume fractions of ferrite and austenite were measured to be approximately equal, and the distribution of alloying elements in the strip was further homogenized. The cold-rolled and annealed sheet exhibited an excellent combination of strength and ductility, with the ultimate tensile strength and elongation having been measured to be 1000 MPa and 65 pct, respectively. The microstructural evolution during deformation was investigated by XRD, EBSD, and TEM, indicating that ferrite and austenite had different deformation mechanisms. The deformation of ferrite phase was dominated by dislocation slipping, and the deformation of austenite phase was mainly controlled by martensitic transformation in the sequence of γ→ ɛ-martensite→ α'-martensite, leading to the improvement of strength and plasticity by the so-called transformation-induced plasticity (TRIP) effect. By contrast, lean duplex stainless steels of Fe-21Cr-6Mn-0.5N and Fe-23Cr-7Mn-0.6N fabricated by twin-roll strip casting did not show TRIP effects and exhibited lower strength and elongation as compared to Fe-19Cr-6Mn-0.4N.

Highly Stable K2SiF6:Mn4+@K2SiF6 Composite Phosphor with Narrow Red Emission for White LEDs.

PubMed

Huang, Lin; Liu, Yong; Yu, Jinbo; Zhu, Yiwen; Pan, Fengjuan; Xuan, Tongtong; Brik, Mikhail G; Wang, Chengxin; Wang, Jing

2018-05-30

Poor water resistance and nongreen synthesis remain great challenges for commercial narrow red-emitting phosphor A 2 MF 6 :Mn 4+ (A = alkali metal ion; M = Si, Ge, Ti) for solid-state lighting and display. We develop here a simple and green growth route to synthesize homogeneous red-emitting composite phosphor K 2 SiF 6 :Mn 4+ @K 2 SiF 6 (KSFM@KSF) with excellent water resistance and high efficiency without the usage of toxic and volatile hydrogen fluoride solution. After immersing into water for 6 h, the as-obtained water-resistant products maintain 76% of the original emission intensity, whereas the emission intensity of non-water-resistant ones steeply drops down to 11%. A remarkable result is that after having kept at 85% humidity and at 85 °C for 504 h (21 days), the emission intensity of the as-obtained water-resistant products is at 80-90%, from its initial value, which is 2-3 times higher than 30-40% for the non-water-resistant products. The surface deactivation-enabled growth mechanism for these phosphors was proposed and investigated in detail. We found that nontoxic H 3 PO 4 /H 2 O 2 aqueous solution promotes the releasing and decomposition of the surface [MnF 6 ] 2- ions and the transformation of the KSFM surface to KSF, which finally contributes to the homogeneous KSFM@KSF composite structure. This composite structure strategy was also successfully used to treat KSFM phosphor prepared by other methods. We believe that the results obtained in the present paper will open the pathway for the large-scale environmentally friendly synthesis of the excellent antimoisture narrow red-emitting A 2 MF 6 :Mn 4+ phosphor to be used for white light-emitting diode applications.

Characterization of air manganese exposure estimates for residents in two Ohio towns

PubMed Central

Colledge, Michelle A.; Julian, Jaime R.; Gocheva, Vihra V.; Beseler, Cheryl L.; Roels, Harry A.; Lobdell, Danelle T.; Bowler, Rosemarie M.

2016-01-01

This study was conducted to derive receptor-specific outdoor exposure concentrations of total suspended particulate (TSP) and respirable (dae ≤ 10 μm) air manganese (air-Mn) for East Liverpool and Marietta (Ohio) in the absence of facility emissions data, but where long-term air measurements were available. Our “site-surface area emissions method” used U.S. Environmental Protection Agency’s (EPA) AERMOD (AMS/EPA Regulatory Model) dispersion model and air measurement data to estimate concentrations for residential receptor sites in the two communities. Modeled concentrations were used to create ratios between receptor points and calibrated using measured data from local air monitoring stations. Estimated outdoor air-Mn concentrations were derived for individual study subjects in both towns. The mean estimated long-term air-Mn exposure levels for total suspended particulate were 0.35 μg/m3 (geometric mean [GM]) and 0.88 μg/m3 (arithmetic mean [AM]) in East Liverpool (range: 0.014–6.32 μg/m3) and 0.17 μg/m3 (GM) and 0.21 μg/m3 (AM) in Marietta (range: 0.03–1.61 μg/m3). Modeled results compared well with averaged ambient air measurements from local air monitoring stations. Exposure to respirable Mn particulate matter (PM10; PM <10 μm) was higher in Marietta residents. Implications Few available studies evaluate long-term health outcomes from inhalational manganese (Mn) exposure in residential populations, due in part to challenges in measuring individual exposures. Local long-term air measurements provide the means to calibrate models used in estimating long-term exposures. Furthermore, this combination of modeling and ambient air sampling can be used to derive receptor-specific exposure estimates even in the absence of source emissions data for use in human health outcome studies. PMID:26211636

Ba2NiOsO6: a Dirac-Mott insulator with ferromagnetism near 100 K

NASA Astrophysics Data System (ADS)

Feng, Hl; Calder, S.; Ghimire, M.; Yuan, Yh; Shirako, Y.; Tsujimoto, Y.; Matsushita, Y.; Hu, Z.; Kuo, Cy; Tjeng, Lh; Pi, Tw; Soo, Yl; He, Jf; Tanaka, M.; Katsuya, Y.; Richte, M.; Yamaura, Kazunari

The ferromagnetic semiconductor Ba2NiOsO6(Tmag 100 K) was synthesized at 6 GPa and 1500 ° C. It crystallizes into a double perovskite structure [Fm-3 m; a = 8.0428(1)], where the Ni2+ and Os6+ ions are perfectly ordered at the perovskite B-site. We show that the spin-orbit coupling of Os6+ plays an essential role in opening the charge gap. The magnetic state was investigated by density functional theory calculations and powder neutron diffraction. The latter revealed a collinear ferromagnetic order in a >21-kOe magnetic field at 5 K. The ferromagnetic gapped state is fundamentally different from that of known dilute magnetic semiconductors such as (Ga,Mn)As and (Cd,Mn)Te (Tmag<180 K), the spin-gapless semiconductor Mn2CoAl (Tmag 720 K), and the ferromagnetic insulators EuO (Tmag 70 K) and Bi3Cr3O11(Tmag 220 K). It is also qualitatively different from known ferrimagnetic insulator/semiconductors, which are characterized by an antiparallel spin arrangement. Our report of cubic Ba2NiOsO6 heralds a new class of FM insulator oxides, which may be useful in developing a practical magnetic semiconductor that can be employed in spintronic and quantum magnetic devices.

Permanganate oxidation of α-amino acids: kinetic correlations for the nonautocatalytic and autocatalytic reaction pathways.

PubMed

Perez-Benito, Joaquin F

2011-09-08

The reactions of permanganate ion with seven α-amino acids in aqueous KH(2)PO(4)/K(2)HPO(4) buffers have been followed spectrophotometrically at two different wavelengths: 526 nm (decay of MnO(4)(-)) and 418 nm (formation of colloidal MnO(2)). All of the reactions studied were autocatalyzed by colloidal MnO(2), with the contribution of the autocatalytic reaction pathway decreasing in the order glycine > l-threonine > l-alanine > l-glutamic acid > l-leucine > l-isoleucine > l-valine. The rate constants corresponding to the nonautocatalytic and autocatalytic pathways were obtained by means of either a differential rate law or an integrated one, the latter requiring the use of an iterative method for its implementation. The activation parameters for the two pathways were determined and analyzed to obtain statistically significant correlations for the series of reactions studied. The activation enthalpy of the nonautocatalytic pathway showed a strong, positive dependence on the standard Gibbs energy for the dissociation of the protonated amino group of the α-amino acid. Linear enthalpy-entropy correlations were found for both pathways, leading to isokinetic temperatures of 370 ± 21 K (nonautocatalytic) and 364 ± 28 K (autocatalytic). Mechanisms in agreement with the experimental data are proposed for the two reaction pathways.

An evaluation of soil colonisation potential of selected fungi and their production of ligninolytic enzymes for use in soil bioremediation applications.

PubMed

McErlean, Colum; Marchant, Roger; Banat, Ibrahim M

2006-08-01

Initially sixteen fungi were screened for potential ligninolytic activity using decolourisation of a polymeric dye Poly R-478. From this, four fungi were selected, Trametes versicolor, Pleurotus ostreatus, Collybia sp., and an isolate (identified as Rhizoctonia solani) isolated from a grassland soil. Differences in the ligninolytic enzyme profiles of each of the fungi were observed. All of the four fungi tested produced MnP and laccase while the Collybia sp. and R. solani produced LiP in addition. Enzyme activity levels also varied greatly over the 21 days of testing with T. versicolor producing levels of MnP and laccase three to four times greater than the other fungi. The four fungi were then tested for their ability to colonise sand, peat (forest) and basalt and marl mixed till (field) soils through visual measurement and biomass detection in soil microcosms. Trametes versicolor and the Collybia sp. failed to grow in any of the non-sterilised soils whereas the R. solani and P. ostreatus isolates grew satisfactorily. Primers were designed to detect MnP and laccase genes in P. ostreatus and RTPCR was used to detect that these genes are expressed in forest and field soils.

Time-of-flight mass measurements for nuclear processes in neutron star crusts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Estrade, Alfredo; Matos, M.; Schatz, Hendrik

2011-01-01

The location of electron capture heat sources in the crust of accreting neutron stars depends on the masses of extremely neutron-rich nuclei. We present first results from a new implementation of the time-of-flight technique to measure nuclear masses of rare isotopes at the National Supercon- ducting Cyclotron Laboratory. The masses of 16 neutron-rich nuclei in the Sc Ni element range were determined simultaneously, improving the accuracy compared to previous data in 12 cases. The masses of 61V, 63Cr, 66Mn, and 74Ni were measured for the first time with mass excesses of 30.510(890) MeV, 35.280(650) MeV, 36.900(790) MeV, and 49.210(990) MeV,more » respectively. With the measurement of the 66Mn mass, the location of the two dominant heat sources in the outer crust of accreting neutron stars, which exhibit so called superbursts, is now experimentally constrained. We find that the location of the 66Fe 66Mn electron capture transition occurs sig- nificantly closer to the surface than previously assumed because our new experimental Q-value is 2.1 MeV smaller than predicted by the FRDM mass model. The results also provide new insights into the structure of neutron-rich nuclei around N = 40.« less

Calculation of stochastic broadening due to low mn magnetic perturbation in the simple map in action-angle coordinates

NASA Astrophysics Data System (ADS)

Hinton, Courtney; Punjabi, Alkesh; Ali, Halima

2009-11-01

The simple map is the simplest map that has topology of divertor tokamaks [A. Punjabi, H. Ali, T. Evans, and A. Boozer, Phys. Let. A 364, 140--145 (2007)]. Recently, the action-angle coordinates for simple map are analytically calculated, and simple map is constructed in action-angle coordinates [O. Kerwin, A. Punjabi, and H. Ali, Phys. Plasmas 15, 072504 (2008)]. Action-angle coordinates for simple map cannot be inverted to real space coordinates (R,Z). Because there is logarithmic singularity on the ideal separatrix, trajectories cannot cross separatrix [op cit]. Simple map in action-angle coordinates is applied to calculate stochastic broadening due to the low mn magnetic perturbation with mode numbers m=1, and n=±1. The width of stochastic layer near the X-point scales as 0.63 power of the amplitude δ of low mn perturbation, toroidal flux loss scales as 1.16 power of δ, and poloidal flux loss scales as 1.26 power of δ. Scaling of width deviates from Boozer-Rechester scaling by 26% [A. Boozer, and A. Rechester, Phys. Fluids 21, 682 (1978)]. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.

New routes to polymetallic clusters: fluoride-based tri-, deca-, and hexaicosametallic MnIII clusters and their magnetic properties.

PubMed

Jones, Leigh F; Rajaraman, Gopalan; Brockman, Jonathon; Murugesu, Muralee; Sanudo, E Carolina; Raftery, Jim; Teat, Simon J; Wernsdorfer, Wolfgang; Christou, George; Brechin, Euan K; Collison, David

2004-10-11

The syntheses, structures and magnetic properties of three new MnIII clusters, [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1), [Mn(0O6(OH)2(bta)8(py)8F8] (2) and [NHEt3]2[Mn3O(bta)6F3] (3), are reported (bta=anion of benzotriazole), thereby demonstrating the utility of MnF3 as a new synthon in Mn cluster chemistry. The "melt" reaction (100 degrees C) between MnF(3) and benzotriazole (btaH, C6H5N3) under an inert atmosphere, followed by dissolution in MeOH produces the cluster [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1) after two weeks. Complex 1 crystallizes in the triclinic space group P1, and consists of a complicated array of metal tetrahedra linked by mu3-O2- ions, mu3- and mu2-OH- ions, mu2-MeO- ions and mu2-bta- ligands. The "simpler" reaction between MnF3 and btaH in boiling MeOH (50 degrees C) also produces complex 1. If this reaction is repeated in the presence of pyridine, the decametallic complex [Mn10O6(OH)2(bta)8(py)8F8] (2) is produced. Complex 2 crystallizes in the triclinic space group P1 and consists of a "supertetrahedral" [Mn(III)10] core bridged by six mu3-O2- ions, two mu3-OH- ions, four mu2-F- ions and eight mu2-bta- ions. The replacement of pyridine by triethylamine in the same reaction scheme produces the trimetallic species [NHEt3]2[Mn3O(bta)6F3] (3). Complex 3 crystallises in the monoclinic space group P2(1)/c and has a structure analogous to that of the basic metal carboxylates of general formula [M3O(RCO2)6L3]0/+, which consists of an oxo-centred metal triangle with mu2-bta- ligands bridging each edge of the triangle and the fluoride ions acting as the terminal ligands. DC magnetic susceptibility measurements in the 300-1.8 K and 0.1-7 T ranges were investigated for all three complexes. For each, the value of chi(M)T decreases with decreasing temperatures; this indicates the presence of dominant antiferromagnetic exchange interactions in 1-3. For complex 1, the low-temperature value of chi(M)T is 10 cm(3) K mol(-1) and fitting of the magnetisation data gives S=4, g=2.0 and D=-0.90 cm(-1). For complex 2, the value of chi(M)T falls to a value of approximately 5.0 cm(3) K mol(-1) at 1.8 K, which is consistent with a small spin ground state. For the triangular complex 3, the best fit to the experimental chi(M)T versus T data was obtained for the following parameters: Ja = -5.01 cm(-1), Jb = +9.16 cm(-1) and g=2.00, resulting in an S=2 spin ground state. DFT calculations on 3, however, suggest an S=1 or S=0 ground state with J(a)=-2.95 cm(-1) and J(b)=-2.12 cm(-1). AC susceptibility measurements performed on 1 in the 1.8-4.00 K range show the presence of out-of-phase AC susceptibility signals, but no peaks. Low-temperature single-crystal studies performed on 1 on an array of micro-SQUIDS show the time- and temperature-dependent hysteresis loops indicative of single-molecule magnetism behaviour.

Middendorfite, K3Na2Mn5Si12(O,OH)36 · 2H2O, a new mineral species from the Khibiny pluton, Kola Peninsula

NASA Astrophysics Data System (ADS)

Pekov, I. V.; Chukanov, N. V.; Dubinchuk, V. T.; Zadov, A. E.

2007-12-01

Middendorfite, a new mineral species, has been found in a hydrothermal assemblage in Hilairite hyperperalkaline pegmatite at the Kirovsky Mine, Mount Kukisvumchorr apatite deposit, Khibiny alkaline pluton, Kola Peninsula, Russia. Microcline, sodalite, cancrisilite, aegirine, calcite, natrolite, fluorite, narsarsukite, labuntsovite-Mn, mangan-neptunite, and donnayite are associated minerals. Middendorfite occurs as rhombshaped lamellar and tabular crystals up to 0.1 × 0.2 × 0.4 mm in size, which are combined in worm-and fanlike segregations up to 1 mm in size. The color is dark to bright orange, with a yellowish streak and vitreous luster. The mineral is transparent. The cleavage (001) is perfect, micalike; the fracture is scaly; flakes are flexible but not elastic. The Mohs hardness is 3 to 3.5. Density is 2.60 g/cm3 (meas.) and 2.65 g/cm3 (calc.). Middendorfite is biaxial (-), α = 1.534, β = 1.562, and γ = 1.563; 2 V (meas.) = 10°. The mineral is pleochroic strongly from yellowish to colorless on X through brown on Y and to deep brown on Z. Optical orientation: X = c. The chemical composition (electron microprobe, H2O determined with Penfield method) is as follows (wt %): 4.55 Na2O, 10.16 K2O, 0.11 CaO, 0.18 MgO, 24.88 MnO, 0.68 FeO, 0.15 ZnO, 0.20 Al2O3, 50.87 SiO2, 0.17 TiO2, 0.23 F, 7.73 H2O; -O=F2-0.10, total is 99.81. The empirical formula calculated on the basis of (Si,Al)12(O,OH,F)36 is K3.04(Na2.07Ca0.03)Σ2.10(Mn4.95Fe0.13Mg0.06Ti0.03Zn0.03)Σ5.20(Si11.94Al0.06)Σ12O27.57(OH)8.26F0.17 · 1.92H2O. The simplified formula is K3Na2Mn5Si12(O,OH)36 · 2H2O. Middenforite is monoclinic, space group: P21/ m or P21. The unit cell dimensions are a = 12.55, b = 5.721, c = 26.86 Å; β = 114.04°, V = 1761 Å3, Z = 2. The strongest lines in the X-ray powder pattern [ d, Å, ( I)( hkl)] are: 12.28(100)(002), 4.31(81)(11overline 4 ), 3.555(62)(301, 212), 3.063(52)(008, 31overline 6 ), 2.840(90)(312, 021, 30overline 9 ), 2.634(88)(21overline 9 , 1.0.overline 1 0, 12overline 4 ), 2.366(76)(22overline 6 , 3.1.overline 1 0, 32overline 3 ), 2.109(54)(42 33, 42 44, 51overline 9 , 414), 1.669(64)(2.2.overline 1 3, 3.2.overline 1 3, 62overline 3 , 6.1.overline 1 3), 1.614(56)(5.0.overline 1 6, 137, 333, 71overline 1 ). The infrared spectrum is given. Middendorfite is a phyllosilicate related to bannisterite, parsenttensite, and the minerals of the ganophyllite and stilpnomelane groups. The new mineral is named in memory of A.F. von Middendorff (1815 1894), an outstanding scientist, who carried out the first mineralogical investigations in the Khibiny pluton. The type material of middenforite has been deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

The expression of superoxide dismutase in Mytilus coruscus under various stressors.

PubMed

Wu, Jiong; Bao, Miaomiao; Ge, Delong; Huo, Liping; Lv, Zhenming; Chi, Changfeng; Liao, Zhi; Liu, Huihui

2017-11-01

Superoxide dismutases (SODs), a by-product of antioxidative defence system, protects organisms for eliminating excess reactive oxygen species (ROS) and maintaining the redox balance of immune system. The complete open reading frames (ORFs) of Cu/Zn-SOD and Mn-SOD were identified from Mytilus coruscus (designated as McSOD and MnSOD) by homologous cloning. The sequence lengths were 474bp and 687bp, encoding 157 and 228 amino acids respectively. The deduced amino acid sequences of McSOD and MnSOD shared high identities with Cu/Zn-SOD and Mn-SOD from other mollusca. The distributions of McSOD and MnSOD were detected in six tissues including adductor, hemocyte, gill, gonad, mantle and hepatopancreas, and the highest expressions were both in gills. The temporal expression of McSOD and MnSOD were up-regulated in gills under a variety of stress factors, including Vibrio parahemolyticus, Aeromonas hydrophila, Cu 2+ and Pb 2+ . After being challenged with V. Parahemolyticus, the expressions of McSOD and MnSOD were increased rapidly at the initial hours, reaching the peaks of 4.9-fold and 15.3-fold respectively, and got to the highest levels of 43.5-fold and 7.1-fold after being challenged with A. hydrophila. The highest point of McSOD mRNA appeared at 15 d after being exposed to copper (7-fold at 0.5 mg/L and 13.2-fold at 1.5 mg/L), except for 0.1 mg/L group of Cu 2+ maintaining to the normal level, but plumbum at 1 d (2.4-fold at 1.0 mg/L and 4.4-fold at 3.0 mg/L) and at 15 d (2.1-fold at 0.2 mg/L). The temporal expression peaks of MnSOD appeared differently after exposing to copper of various concentrations (0.1 mg/L at 10 d with 4.7-fold, 0.5 mg/L at 1 d with 17.9-fold and 1.5 mg/L at 3 d with 13.2-fold). Whereas in plumbum exposing treatments, the 3.0 mg/L group jumped to the peak at 1 d (18.2-fold), the 0.2 mg/L and 1.0 mg/L groups had little change and maintained at the normal level throughout the experiment. The results provided several new evidences for further understanding of the regulatory mechanism of SOD on the innate immune system in bivalve. Copyright © 2017 Elsevier Ltd. All rights reserved.

Virologic Differences Do Not Fully Explain the Diversification of Swine Influenza Viruses in the United States

PubMed Central

Sun, Yilun; Yoon, Sun-Woo; Jeevan, Trushar; Dlugolenski, Daniel; Tripp, Ralph A.; Tang, Li

2016-01-01

ABSTRACT Influenza A(H1N1) viruses entered the U.S. swine population following the 1918 pandemic and remained genetically stable for roughly 80 years. In 1998, there was an outbreak of influenza-like illness among swine that was caused by A(H3N2) viruses containing the triple reassortant internal gene (TRIG) cassette. Following the TRIG cassette emergence, numerous reassortant viruses were isolated in nature, suggesting that the TRIG virus had an enhanced ability to reassort compared to the classical swine virus. The present study was designed to quantify the relative reassortment capacities of classical and TRIG swine viruses. Reverse genetic viruses were generated from the classical H1N1 virus A/swine/MN/37866/1999 (MN/99), the TRIG virus A/swine/NC/18161/2002 (NC/02), and a seasonal human H3N2 virus, A/TX/6/1996 (TX/96), to measure in vitro reassortment and growth potentials. After coinfection with NC/02 or MN/99 plus TX/96, H1/H3 double-positive cells were identified. Delayed TX/96 infection was fully excluded by both swine viruses. We then analyzed reassortant H3 viruses. Seventy-seven of 81 (95.1%) TX/96-NC/02 reassortants contained at least one polymerase gene segment from NC/02, whereas only 34 of 61 (55.7%) MN/99-TX/96 reassortants contained at least one polymerase gene segment from MN/99. Additionally, 38 of 81 (46.9%) NC/02-TX/96 reassortants contained all NC/02 polymerase gene segments, while none of the MN/99-TX/96 reassortants contained all MN/99 polymerase genes. There were 21 H3 reassortants between MN/99 and TX/96, compared to only 17 H3 reassortants between NC/02 and TX/96. Overall, the results indicate that there are no distinct differences in the ability of the TRIG to reassort with a human virus compared to the classical swine virus. IMPORTANCE There appear to be no differences in the abilities of classical swine and TRIG swine viruses to exclude a second virus, suggesting that under the right circumstances both viruses have similar opportunities to reassort. The increased percentage of TRIG polymerase gene segments in reassortant H3 viruses indicates that these viruses may be more compatible with gene segments from other viruses; however, this needs to be investigated further. Nevertheless, the classical swine virus also showed the ability to reassort, suggesting that factors other than reassortment capacity alone are responsible for the different epidemiologies of TRIG and classical swine viruses. The post-TRIG diversity was likely driven by increased intensive farming practices rather than virologic properties. Our results indicate that host ecology can be a significant factor in viral evolution. PMID:27581984

Final Technical Report for the project titled "Manganese Based Permanent Magnet with 40 MGOe at 200°C"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Jun; Ames Lab., Ames, IA; Pacific Northwest National Lab.

2015-12-31

The objective of project was to develop MnBi based permanent magnet for high temperature application (~150°C). This objective is derived based on MnBi’s unique positive temperature dependence of coercivity, which is doubled from ~1 T at RT to ~2.5 T at 200°C. Because of its limited magnetization (<0.9 T at RT), the MnBi magnet is best suited to fill in the gap between rare earth based NdFeB-Dy or SmCo magnet (20 MGOe) and the AlNiCo magnet (10 MGOe) at 150°C. It is expected that if successfully developed, MnBi will effectively mitigate the world’s demand on Dy. Before this project, themore » highest LTP content in MnBi powder is about 90% if the quantity of the powder is less than 5 gram (using melt-spin method); or 80% if the quantity is greater than 100 gram (using conventional powder metallurgical method such as arc melting and annealing). After this project, large quantities (5kg/batch) with high LPT phase content (>92 wt%) can be routinely synthesized. This achievement is made possible by the newly developed synthesis method based on conventional metallurgical processing technique involving arc melting, two-stage ingot annealing, grinding, sieving, and vacuum annealing. Before this project, the finest powder particle size is about 35 μm with overall powder composition maintaining at about 85% LTP phase. The reason why LTP phase content is listed along with particle size is because LTP MnBi is easy to decompose when exposed to temperature higher than 350 °C. As result, only low energy ball milling can be used to refine the particle size; moreover, the ball milling time cannot exceed 4 hrs, or else the decomposed LTP MnBi phase will exceed 10%. After this project, the finest powder size is reduced to 1~5 μm while maintain the 90% LTP MnBi phase content. This achievement is made possible by a newly developed cryogenic ball milling system, which provides -70 °C ambient for the rolling container. Before this project, it is not clear if MnBi will ferromagnetically exchange-couple with soft magnetic phase such as Fe or Co. After this project, it is established that MnBi will ferromagnetically exchange couple with Co, but not with Fe. It is also possible for MnBi to ferromagnetically exchange couple with Fe-Co alloy, but the amount of Fe cannot be more than 50 at.%. This conclusion is made possible by a series of electronic structure calculation followed by a series of thin film experimentation. As the result, 25 MGOe energy product was demonstrated using a MnBi-Co film. Before this project, the highest energy product for a bulk MnBi magnet is about 5 MGOe with 70% green density, and near-fully dense magnet is not available. After this project, the highest energy density is about 8.6 MGOe with 95% green density. This achievement is made possible by a modified warm-compaction system developed at University of Texas at Arlington. This system has 2.1 T alignment field vs the previous 1.8 T, and the compaction ambient maintains <1 ppm oxygen partial pressure. The estimated cost of MnBi magnet is about $110/kg when conventional magnet fabrication method is used, and about $84/kg when warm extrusion method is used. In comparison the cost of NdFeB, SmCo, AlNiCo, and Sr-Ferrite magnets is $150/kg, $180/kg, $119/kg, and $20/kg, respectively. The near term future work should focus on further improve the purity of the LTP MnBi, pushing it from the current 91 wt.% to 99 wt.%. If successful, the increased 8% LTP phase will increase the remanent magnetization, which in turn, increase the energy product. In addition, high reduction ratio warm extrusion method should be investigated to further push the texture to >90%.« less

Persistence of deposited metals in the lungs after stainless steel and mild steel welding fume inhalation in rats.

PubMed

Antonini, James M; Roberts, Jenny R; Stone, Samuel; Chen, Bean T; Schwegler-Berry, Diane; Chapman, Rebecca; Zeidler-Erdely, Patti C; Andrews, Ronnee N; Frazer, David G

2011-05-01

Welding generates complex metal fumes that vary in composition. The objectives of this study were to compare the persistence of deposited metals and the inflammatory potential of stainless and mild steel welding fumes, the two most common fumes used in US industry. Sprague-Dawley rats were exposed to 40 mg/m(3) of stainless or mild steel welding fumes for 3 h/day for 3 days. Controls were exposed to filtered air. Generated fume was collected, and particle size and elemental composition were determined. Bronchoalveolar lavage was done on days 0, 8, 21, and 42 after the last exposure to assess lung injury/inflammation and to recover lung phagocytes. Non-lavaged lung samples were analyzed for total and specific metal content as a measure of metal persistence. Both welding fumes were similar in particle morphology and size. Following was the chemical composition of the fumes-stainless steel: 57% Fe, 20% Cr, 14% Mn, and 9% Ni; mild steel: 83% Fe and 15% Mn. There was no effect of the mild steel fume on lung injury/inflammation at any time point compared to air control. Lung injury and inflammation were significantly elevated at 8 and 21 days after exposure to the stainless steel fume compared to control. Stainless steel fume exposure was associated with greater recovery of welding fume-laden macrophages from the lungs at all time points compared with the mild steel fume. A higher concentration of total metal was observed in the lungs of the stainless steel welding fume at all time points compared with the mild steel fume. The specific metals present in the two fumes were cleared from the lungs at different rates. The potentially more toxic metals (e.g., Mn, Cr) present in the stainless steel fume were cleared from the lungs more quickly than Fe, likely increasing their translocation from the respiratory system to other organs.

Effects of hydroxy trace minerals on oxidative metabolism, cytological endometritis, and performance of transition dairy cows.

PubMed

Yasui, T; Ryan, C M; Gilbert, R O; Perryman, K R; Overton, T R

2014-01-01

Multiparous Holstein cows (n=60) were used to determine effects of supplementing hydroxy forms of Zn, Cu, and Mn compared with 2 other common supplementation strategies on oxidative metabolism, cytological endometritis, and performance of transition cows. After a 1-wk pretreatment period, cows were assigned randomly to 1 of 3 dietary treatments from 21 d before expected calving through 84 d postcalving. Dietary treatments administered by daily top-dressing included (1) inorganic sulfate forms of Zn, Cu, and Mn (ITM); (2) a blend (75:25) of sulfates and organic complexes of Zn, Cu, and Mn (ITM/OTM); and (3) hydroxy trace minerals (HTM) of Zn, Cu, and Mn. The resulting dietary concentrations of supplemental Zn, Cu, and Mn were similar among treatments and averaged 40, 10, and 27 mg/kg, respectively, before calving and 59, 15, and 40 mg/kg, respectively, after calving. Total concentrations of Zn, Cu, and Mn averaged 80, 16, and 62 mg/kg during the prepartum period and 102, 23, and 75 mg/kg, respectively, during the postpartum period. Overall, effects of treatment on milk yield and milk composition were not significant. Cows fed HTM during the prepartum period had higher body weight (BW) than those fed ITM during the prepartum period and had higher BW during the postpartum period than those fed the other treatments; however, BW change, body condition score, and body condition score change were not affected by treatment. Plasma total antioxidant capacity was lower in cows fed HTM than ITM but was not different from cows fed ITM/OTM. Cows fed HTM tended to have lower concentrations of plasma thiobarbituric acid reactive substances than those fed ITM during the whole study period, but plasma thiobarbituric acid reactive substances were not different between HTM and ITM/OTM. Plasma haptoglobin was lower in cows fed HTM than ITM/OTM at 1 wk postpartum. Endometrial cytology 7d postcalving and cytological endometritis as assessed on 1d between 40 and 60 d postcalving was not affected by treatment. In conclusion, supplementation with HTM sources of Zn, Cu, and Mn modulated plasma variables related to oxidative metabolism compared with supplementation with ITM; however, HTM and ITM/OTM resulted in similar responses. Furthermore, the source of trace minerals did not affect performance or uterine health in this experiment. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

DRDC Ottawa Participation in the SILENE Accident Dosimetry Intercomparison Exercise. June 10-21, 2002

DTIC Science & Technology

2002-11-01

of CaF2:Mn and A120 3 TLDs for gamma-ray dosimetry ). In addition, DRDC Ottawa has recently substantially expanded its efforts in radiation dosimetry ...use of any real- time electronic dosimeter. Foils have long been proposed and used for criticality dosimetry (as well as for general monitoring of...ray Dosimetry DRDC Ottawa offers a number (over five) of various thermoluminescence dosimetry ( TLD ) systems. The choice of any particular TLD depends

What does the Sr-substituted 2.1 Å resolution crystal structure of photosystem II reveal about the water oxidation mechanism?

PubMed

Terrett, Richard; Petrie, Simon; Pace, Ron J; Stranger, Robert

2014-03-25

A density functional study of the Sr-substituted photosystem II water oxidising complex demonstrates that its recent X-ray crystal structure is consistent with a (Mn(III))4 oxidation state pattern, and with a Sr-bound hydroxide ion. The Sr-water-hydroxide interactions rationalize differences in the exchange rates of substrate water and kinetics of dioxygen bond formation relative to the Ca-containing structure.

Dynamics of an n = 1 explosive instability and its role in high-β disruptions

NASA Astrophysics Data System (ADS)

Aydemir, A. Y.; Park, B. H.; In, Y. K.

2018-01-01

Some low-n kink-ballooning modes not far from marginal stability are shown to exhibit a bifurcation between two very distinct nonlinear paths that depends sensitively on the background transport levels and linear perturbation amplitudes. The particular instability studied in this work is an n=1 mode dominated by an m/n=2/1 component. It is driven by a large pressure gradient in weak magnetic shear and can appear in various high- \

Short of General War: Perspectives on the Use of Military Power in the 21st Century

DTIC Science & Technology

2010-04-01

Paul , MN: Zenith Press, 2004. Hammes’ work is one articulation of this argument. 5. United States Joint Forces Command, “The JOE 2008, Joint Operating...this approach would actually be counterproductive and might be more harmful than beneficial to American interests. According to Paul Sanders, 18...A New Security Strategy for America, Washington, DC: Brookings Institution Press, 1999, p. 55. 50. Paul J. Sanders, “Not the Way to Intervene

Effects of hydrogen fugacity and confining pressure on the interdiffusion rate of NaSi-CaAl in plagioclase

NASA Astrophysics Data System (ADS)

Yund, Richard A.; Snow, Eleanour

1989-08-01

Average? values for NaSi-CaAl interdiffusion in the compositional interval from An0 to An26 have been determined at 1000°C by the method of lamellar homogenization. At 1500 MPa confining pressure (P), ? increases 1 order of magnitude (5.0×10-21 to 4.0×10-20 m2/s) for 4 orders of magnitude increase in hydrogen fugacity (0.029, Mn3O4-Mn2O3 buffer, to 197 MPa, FeO-Fe3O4 buffer). At constant hydrogen fugacity (fH2), ? increases rapidly at low pressure and becomes nearly independent of P above 1000 MPa. (For fH2 = 0.1 MPa, ? = 2.8 × 10-22 m2/s at P = 0.1 MPa, 5.0 × 10-21 at P = 500, 1.3×10-20 at P = 1000, and 1.4×10-20 at P = 1500). The dependence of ? on increasing pressure, when a hydrogen-related species is present, is believed to be due to an increase in the concentration of the structural defect associated with increase in the hydrogen impurity. In most crustal igneous rocks, which are internally buffered near quartz-fayalite-magnetite, the dependence of ? on fH2 is relatively minor compared to the effect of confining pressure.

Rotation profile flattening and toroidal flow shear reversal due to the coupling of magnetic islands in tokamaks

DOE PAGES

Tobias, B.; Chen, M.; Classen, I. G. J.; ...

2016-04-15

The electromagnetic coupling of helical modes, including those having different toroidal mode numbers, modifies the distribution of toroidal angular momentum in tokamak discharges. This can have deleterious effects on other transport channels as well as on magnetohydrodynamic (MHD) stability and disruptivity. At low levels of externally injected momentum, the coupling of core-localized modes initiates a chain of events, whereby flattening of the core rotation profile inside successive rational surfaces leads to the onset of a large m/n = 2/1 tearing mode and locked-mode disruption. Furthermore, with increased torque from neutral beam injection, neoclassical tearing modes in the core may phase-lockmore » to each other without locking to external fields or structures that are stationary in the laboratory frame. The dynamic processes observed in these cases are in general agreement with theory, and detailed diagnosis allows for momentum transport analysis to be performed, revealing a significant torque density that peaks near the 2/1 rational surface. However, as the coupled rational surfaces are brought closer together by reducing q95, additional momentum transport in excess of that required to attain a phase-locked state is sometimes observed. Rather than maintaining zero differential rotation (as is predicted to be dynamically stable by single-fluid, resistive MHD theory), these discharges develop hollow toroidal plasma fluid rotation profiles with reversed plasma flow shear in the region between the m/n = 3/2 and 2/1 islands. Additional forces expressed in this state are not readily accounted for, and therefore, analysis of these data highlights the impact of mode coupling on torque balance and the challenges associated with predicting the rotation dynamics of a fusion reactor-a key issue for ITER. Published by AIP Publishing.« less

Heterologous expression and structure-function relationship of low-temperature and alkaline active protease from Acinetobacter sp. IHB B 5011(MN12).

PubMed

Salwan, Richa; Sharma, Vivek; Pal, Mohinder; Kasana, Ramesh Chand; Yadav, Sudesh Kumar; Gulati, Arvind

2018-02-01

The gene encoding protease from Acinetobacter sp. IHB B 5011(MN12) was cloned and expressed in Escherichia coli BL21(DE3). The nucleotide sequence revealed 1323bp ORF encoding 441 amino acids protein with molecular weight 47.2kDa. The phylogenetic analysis showed clustering of Alp protease with subtilisin-like serine proteases of S8 family. The amino acid sequence was comprised of N-terminal signal peptide 1-21 amino acids, pre-peptide 22-143 amino acids, peptidase S8 domain 144-434 amino acids, and pro-peptide 435-441 amino acids at C-terminus. Three constructs with signal peptide pET-Alp, without signal peptide pET-Alp1 and peptidase S8 domain pET-Alp2 were prepared for expression in E. coli BL21(DE3). The recombinant proteins Alp1 and Alp2 expressed as inclusion bodies showed ∼50kDa and ∼40kDa bands, respectively. The pre-propeptide ∼11kDa removed from Alp1 resulted in mature protein of ∼35kDa with 1738Umg -1 specific activity. The recombinant protease was optimally active at 40°C and pH 9, and stable over 10-70°C and 6-12pH. The activity at low-temperature and alkaline pH was supported by high R/(R+K) ratio, more glycine, less proline, negatively charged amino acids, less salt bridges and longer loops. These properties suggested the suitability of Alp as additive in the laundry. Copyright © 2017. Published by Elsevier B.V.

Multireversible redox processes in pentanuclear bis(triple-helical) manganese complexes featuring an oxo-centered triangular {Mn(II)2Mn(III)(μ3-O)}5+ or {Mn(II)Mn(III)2(μ3-O)}6+ core wrapped by two {Mn(II)2(bpp)3}-.

PubMed

Romain, Sophie; Rich, Jordi; Sens, Cristina; Stoll, Thibaut; Benet-Buchholz, Jordi; Llobet, Antoni; Rodriguez, Montserrat; Romero, Isabel; Clérac, Rodolphe; Mathonière, Corine; Duboc, Carole; Deronzier, Alain; Collomb, Marie-Noëlle

2011-09-05

A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn(II)(μ-bpp)(3)}(2)Mn(II)(2)Mn(III)(μ-O)](3+) (1(3+)) and [{Mn(II)(μ-bpp)(3)}(2)Mn(II)Mn(III)(2)(μ-O)](4+) (1(4+)). The structure consists of a central {Mn(3)(μ(3)-O)} core of Mn(II)(2)Mn(III) (1(3+)) or Mn(II)Mn(III)(2) ions (1(4+)) which is connected to two apical Mn(II) ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH(3)CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range, assigned to the Mn(II)(4)Mn(III)/Mn(II)(5), Mn(II)(3)Mn(III)(2)/Mn(II)(4)Mn(III), Mn(II)(2)Mn(III)(3)/Mn(II)(3)Mn(III)(2), Mn(II)Mn(III)(4)/Mn(II)(2)Mn(III)(3), and Mn(III)(5)/Mn(II)Mn(III)(4) redox couples. The two first oxidation processes leading to Mn(II)(3)Mn(III)(2) (1(4+)) and Mn(II)(2)Mn(III)(3) (1(5+)) are related to the oxidation of the Mn(II) ions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn(II) ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn(4)(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero-field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn(II) ions. At 40 K, the magnetic behavior is consistent for 1(3+) with two apical S = 5/2 {Mn(II)(bpp)(3)}(-) and one S = 2 noninteracting spins (11.75 cm(3) K mol(-1)), and for 1(4+) with three S = 5/2 noninteracting spins (13.125 cm(3) K mol(-1)) suggesting that the {Mn(II)(2)Mn(III)(μ(3)-O)}(5+) and {Mn(II)Mn(III)(2)(μ(3)-O)}(6+) cores behave at low temperature like S = 2 and S = 5/2 spin centers, respectively. The thermal behavior below 40 K highlights the presence of intracomplex magnetic interactions between the two apical spins and the central core, which is antiferromagnetic for 1(3+) leading to an S(T) = 3 and ferromagnetic for 1(4+) giving thus an S(T) = 15/2 ground state.

Self-penetration--a structural compromise between single networks and interpenetration: magnetic properties and crystal structures of

PubMed

Jensen; Price; Batten; Moubaraki; Murray

2000-09-01

The three-dimensional coordination polymers [Mn(dca)2(H2O)] (1) and [M(dca)(tcm)], M =Co (2), Ni (3), Cu (4), dca =dicyanamide, N(CN)2-, tcm = tricyanomethanide, C(CN)3-, have isomorphous structures. In 1 half the dca ligands coordinate directly (through all three nitrogen atoms) to three Mn atoms (all metal atoms are six-coordinate), while the other half coordinate to two Mn atoms (through the nitrile nitrogens) and hydrogen bond to water molecules coordinated to a third Mn atom (through the amide nitrogen). This dca. H2O structural moiety is disordered over a mirror plane, and is replaced by the structurally equivalent tcm ligand in compounds 2-4. The resulting structures display a new self-penetrating 3,6-connected (2:1) network topology that can be related to, but is different from, the rutile net. The self-penetrating [M(dca)(tcm)] network can be viewed as a structural compromise between the two interpenetrating rutile-like networks of [M(tcm)2] and the single rutile-like network of alpha-[M(dca)2]. The temperature and field dependence of the DC and AC magnetic susceptibilities and magnetisations has been measured for complexes 1-4. Compounds 1-3 exhibit long-range magnetic order with critical temperatures of 6.3 K for 1, 3.5 K for 2 and 8.0 K for 3. The Cu11 compound 4 does not order and is essentially a paramagnet. Hysteresis measurements of coercive field and remnant magnetisation show that 1, 2 and 3 are soft magnets, 1 being a canted-spin antiferromagnet (weak ferromagnet), while 2 and 3 are ferromagnets that display some unusual features in their high-field magnetisation isotherms in comparison to their related alpha-[M(dca)2] phases.

Early Phthalates Exposure in Pregnant Women Is Associated with Alteration of Thyroid Hormones

PubMed Central

Tsai, Chih-Hsin; Liang, Wei-Yen; Li, Sih-Syuan; Huang, Han-Bin

2016-01-01

Introduction Previous studies revealed that phthalate exposure could alter thyroid hormones during the last trimester of pregnancy. However, thyroid hormones are crucial for fetal development during the first trimester. We aimed to clarify the effect of phthalate exposure on thyroid hormones during early pregnancy. Method We recruited 97 pregnant women who were offered an amniocentesis during the early trimester from an obstetrics clinic in southern Taiwan from 2013 to 2014. After signing an informed consent form, we collected amniotic fluid and urine samples from pregnant women to analyze 11 metabolites, including mono-ethyl phthalate (MEP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-(2-ethylhexyl) phthalate (MEHP), mono-butyl phthalate (MnBP), of 9 phthalates using liquid chromatography/ tandem mass spectrometry. We collected blood samples from each subject to analyze serum thyroid hormones including thyroxine (T4), free T4, and thyroid-binding globulin (TBG). Results Three phthalate metabolites were discovered to be >80% in the urine samples of the pregnant women: MEP (88%), MnBP (81%) and MECPP (86%). Median MnBP and MECPP levels in pregnant Taiwanese women were 21.5 and 17.6 μg/g-creatinine, respectively, that decreased after the 2011 Taiwan DEHP scandal. Results of principal component analysis suggested two major sources (DEHP and other phthalates) of phthalates exposure in pregnant women. After adjusting for age, gestational age, TBG, urinary creatinine, and other phthalate metabolites, we found a significantly negative association between urinary MnBP levels and serum T4 (β = –5.41; p-value = 0.012; n = 97) in pregnant women using Bonferroni correction. Conclusion We observed a potential change in the thyroid hormones of pregnant women during early pregnancy after DnBP exposure. Additional study is necessitated to clarify these associations. PMID:27455052

High quality factor manganese-doped aluminum lumped-element kinetic inductance detectors sensitive to frequencies below 100 GHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, G.; Johnson, B. R.; Abitbol, M. H.

Aluminum lumped-element kinetic inductance detectors (LEKIDs) sensitive to millimeter-wave photons have been shown to exhibit high quality factors, making them highly sensitive and multiplexable. The superconducting gap of aluminum limits aluminum LEKIDs to photon frequencies above 100 GHz. Manganese-doped aluminum (Al-Mn) has a tunable critical temperature and could therefore be an attractive material for LEKIDs sensitive to frequencies below 100 GHz if the internal quality factor remains sufficiently high when manganese is added to the film. To investigate, we measured some of the key properties of Al-Mn LEKIDs. A prototype eight-element LEKID array was fabricated using a 40 nm thickmore » film of Al-Mn deposited on a 500 μm thick high-resistivity, float-zone silicon substrate. The manganese content was 900 ppm, the measured T c = 694 ± 1mK, and the resonance frequencies were near 150 MHz. Using measurements of the forward scattering parameter S 21 at various bath temperatures between 65 and 250 mK, we determined that the Al-Mn LEKIDs we fabricated have internal quality factors greater than 2 × 10 5, which is high enough for millimeter-wave astrophysical observations. In the dark conditions under which these devices were measured, the fractional frequency noise spectrum shows a shallow slope that depends on bath temperature and probe tone amplitude, which could be two-level system noise. In conclusion, the anticipated white photon noise should dominate this level of low-frequency noise when the detectors are illuminated with millimeter-waves in future measurements. The LEKIDs responded to light pulses from a 1550 nm light-emitting diode, and we used these light pulses to determine that the quasiparticle lifetime is 60 μs.« less

High quality factor manganese-doped aluminum lumped-element kinetic inductance detectors sensitive to frequencies below 100 GHz

DOE PAGES

Jones, G.; Johnson, B. R.; Abitbol, M. H.; ...

2017-05-29

Aluminum lumped-element kinetic inductance detectors (LEKIDs) sensitive to millimeter-wave photons have been shown to exhibit high quality factors, making them highly sensitive and multiplexable. The superconducting gap of aluminum limits aluminum LEKIDs to photon frequencies above 100 GHz. Manganese-doped aluminum (Al-Mn) has a tunable critical temperature and could therefore be an attractive material for LEKIDs sensitive to frequencies below 100 GHz if the internal quality factor remains sufficiently high when manganese is added to the film. To investigate, we measured some of the key properties of Al-Mn LEKIDs. A prototype eight-element LEKID array was fabricated using a 40 nm thickmore » film of Al-Mn deposited on a 500 μm thick high-resistivity, float-zone silicon substrate. The manganese content was 900 ppm, the measured T c = 694 ± 1mK, and the resonance frequencies were near 150 MHz. Using measurements of the forward scattering parameter S 21 at various bath temperatures between 65 and 250 mK, we determined that the Al-Mn LEKIDs we fabricated have internal quality factors greater than 2 × 10 5, which is high enough for millimeter-wave astrophysical observations. In the dark conditions under which these devices were measured, the fractional frequency noise spectrum shows a shallow slope that depends on bath temperature and probe tone amplitude, which could be two-level system noise. In conclusion, the anticipated white photon noise should dominate this level of low-frequency noise when the detectors are illuminated with millimeter-waves in future measurements. The LEKIDs responded to light pulses from a 1550 nm light-emitting diode, and we used these light pulses to determine that the quasiparticle lifetime is 60 μs.« less

Influence of humic acid and dihydroxy benzoic acid on the agglomeration, adsorption, sedimentation and dissolution of copper, manganese, aluminum and silica nanoparticles - A tentative exposure scenario.

PubMed

Pradhan, Sulena; Hedberg, Jonas; Rosenqvist, Jörgen; Jonsson, Caroline M; Wold, Susanna; Blomberg, Eva; Odnevall Wallinder, Inger

2018-01-01

This work focuses on kinetic aspects of stability, mobility, and dissolution of bare Cu, Al and Mn, and SiO2 NPs in synthetic freshwater (FW) with and without the presence of natural organic matter (NOM). This includes elucidation of particle and surface interactions, metal dissolution kinetics, and speciation predictions of released metals in solution. Dihydroxy benzoic acid (DHBA) and humic acid adsorbed rapidly on all metal NPs (<1 min) via multiple surface coordinations, followed in general by rapid agglomeration and concomitant sedimentation for a large fraction of the particles. In contrast, NOM did not induce agglomeration of the SiO2 NPs during the test duration (21 days). DHBA in concentrations of 0.1 and 1 mM was unable to stabilize the metal NPs for time periods longer than 6 h, whereas humic acid, at certain concentrations (20 mg/L) was more efficient (>24 h). The presence of NOM increased the amount of released metals into solution, in particular for Al and Cu, whereas the effect for Mn was minor. At least 10% of the particle mass was dissolved within 24 h and remained in solution for the metal NPs in the presence of NOM. Speciation modeling revealed that released Al and Cu predominantly formed complexes with NOM, whereas less complexation was seen for Mn. The results imply that potentially dispersed NPs of Cu, Al and Mn readily dissolve or sediment close to the source in freshwater of low salinity, whereas SiO2 NPs are more stable and therefore more mobile in solution.

Application of sequential leaching, risk indices and multivariate statistics to evaluate heavy metal contamination of estuarine sediments: Dhamara Estuary, East Coast of India.

PubMed

Asa, Subas Chandra; Rath, Prasanta; Panda, Unmesh Chandra; Parhi, Pankaj Kumar; Bramha, Satyanarayan

2013-08-01

In the present study, concentration of some selected trace metals (Fe, Mn, Ni, Co, Pb, Zn, Cu, Cr and Cd) are measured in Brahmani, Baitarani river complex along with Dhamara estuary and its near shore. Chemical partitioning has been made to establish association of metals into different geochemical phases. The exchangeable fraction is having high environmental risk among non-lithogeneous phases due to greater potential for mobility into pore water. The metals with highest bio-availability being Cd, Zn and Cr. The metals like Mn, Zn, Cd and Cu represent an appreciable portion in carbonate phase. Fe-Mn oxides act as efficient scavenger for most of the metals playing a prime role in controlling their fate and transport. Among non-lithogeneous phases apart from reducible, Cr showed a significant enrichment in organic phase. Risk assessment code values indicate that all metals except Fe fall under medium-risk zone. In estuarine zone Cd, Zn, Pb and Cr are released to 32.43, 26.10, 21.81 and 20 %, respectively, indicating their significant bio-availability pose high ecological risk. A quantitative approach has been made through the use of different risk indices like enrichment factor, geo-accumulation index and pollution load index. Factor analysis indicates that in riverine zone, Fe-Mn oxides/hydroxides seem to play an important role in scavenging metals, in estuarine zone, organic precipitation and adsorption to the fine silt and clay particles while in coastal zone, co-precipitation with Fe could be the mechanism for the same. Canonical discriminant function indicates that it is highly successful in discriminating the groups as predicted.

[Pollution Characteristics and Potential Ecological Risk of Heavy Metals in Urban Surface Water Sediments from Yongkang].

PubMed

Qi, Peng; Yu, Shu-quan; Zhang, Chao; Liang, Li-cheng; Che, Ji-lu

2015-12-01

In order to understand the pollution characteristics of heavy metals in surface water sediments of Yongkang, we analyzed the concentrations of 10 heavy metals including Ti, Cr, Mn, Co, Ni, Cu, Zn, As, Pb and Fe in 122 sediment samples, explored the underlying source of heavy metals and then assessed the potential ecological risks of those metals by methods of the index of geo-accumulation and the potential ecological risk. The study results showed that: 10 heavy metal contents followed the order: Fe > Ti > Mn > Zn > Cr > Cu > Ph > Ni > As > Co, all heavy metals except for Ti were 1. 17 to 3.78 times higher than those of Zhejiang Jinhua- Quzhou basin natural soils background values; The concentrations of all heavy metals had a significantly correlation between each other, indicating that those heavy metals had similar sources of pollution, and it mainly came from industrial and vehicle pollutions; The pollution extent of heavy metals in sediments by geo-accumulation index (Igeo) followed the order: Cr > Zn > Ni > Cu > Fe > As > Pb >Mn > Ti, thereinto, Cr, Zn, Cu and Ni were moderately polluted or heavily polluted at some sampling sites; The potential ecological risk of 9 heavy metals in sediments were in the following order: Cu > As > Ni > Cr > Pb > Co > Zn > Mn > Ti, Cu and As contributed the most to the total potential ecological risk, accounting for 22.84% and 21. 62% , others had a total of 55.54% , through the ecological risk assessment, 89. 34% of the potential ecological risk indexes ( RI) were low and 10. 66% were higher. The contamination level of heavy metals in Yongkang was slight in total, but was heavy in local areas.

Influence of humic acid and dihydroxy benzoic acid on the agglomeration, adsorption, sedimentation and dissolution of copper, manganese, aluminum and silica nanoparticles – A tentative exposure scenario

PubMed Central

Pradhan, Sulena; Rosenqvist, Jörgen; Jonsson, Caroline M.; Wold, Susanna; Blomberg, Eva; Odnevall Wallinder, Inger

2018-01-01

This work focuses on kinetic aspects of stability, mobility, and dissolution of bare Cu, Al and Mn, and SiO2 NPs in synthetic freshwater (FW) with and without the presence of natural organic matter (NOM). This includes elucidation of particle and surface interactions, metal dissolution kinetics, and speciation predictions of released metals in solution. Dihydroxy benzoic acid (DHBA) and humic acid adsorbed rapidly on all metal NPs (<1 min) via multiple surface coordinations, followed in general by rapid agglomeration and concomitant sedimentation for a large fraction of the particles. In contrast, NOM did not induce agglomeration of the SiO2 NPs during the test duration (21 days). DHBA in concentrations of 0.1 and 1 mM was unable to stabilize the metal NPs for time periods longer than 6 h, whereas humic acid, at certain concentrations (20 mg/L) was more efficient (>24 h). The presence of NOM increased the amount of released metals into solution, in particular for Al and Cu, whereas the effect for Mn was minor. At least 10% of the particle mass was dissolved within 24 h and remained in solution for the metal NPs in the presence of NOM. Speciation modeling revealed that released Al and Cu predominantly formed complexes with NOM, whereas less complexation was seen for Mn. The results imply that potentially dispersed NPs of Cu, Al and Mn readily dissolve or sediment close to the source in freshwater of low salinity, whereas SiO2 NPs are more stable and therefore more mobile in solution. PMID:29420670

Increased frequency of micronuclei in the lymphocytes of patients chronically infected with hepatitis B or hepatitis C virus.

PubMed

Leite, Samantha Therezinha Almeida Pereira; Silva, Marilene Borges da; Pepato, Marco Andrey; Souto, Francisco José Dutra; Santos, Raquel Alves dos; Bassi-Branco, Carmen Lucia

2014-02-01

In this study, we analysed the frequency of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) and evaluated mutagen-induced sensitivity in the lymphocytes of patients chronically infected with hepatitis B virus (HBV) or hepatitis C virus (HCV). In total, 49 patients with chronic viral hepatitis (28 HBV-infected and 21 HCV-infected patients) and 33 healthy, non-infected blood donor controls were investigated. The frequencies (‰) of MN, NPBs and NBUDs in the controls were 4.41 ± 2.15, 1.15 ± 0.97 and 2.98 ± 1.31, respectively. The frequencies of MN and NPBs were significantly increased (p < 0.0001) in the patient group (7.01 ± 3.23 and 2.76 ± 2.08, respectively) compared with the control group. When considered separately, the HBV-infected patients (7.18 ± 3.57) and HCV-infected patients (3.27 ± 2.40) each had greater numbers of MN than did the controls (p < 0.0001). The HCV-infected patients displayed high numbers of NPBs (2.09 ± 1.33) and NBUDs (4.38 ± 3.28), but only the HBV-infected patients exhibited a significant difference (NPBs = 3.27 ± 2.40, p < 0.0001 and NBUDs = 4.71 ± 2.79, p = 0.03) in comparison with the controls. Similar results were obtained for males, but not for females, when all patients or the HBV-infected group was compared with the controls. The lymphocytes of the infected patients did not exhibit sensitivity to mutagen in comparison with the lymphocytes of the controls (p = 0.06). These results showed that the lymphocytes of patients who were chronically infected with HBV or HCV presented greater chromosomal instability.

Recent sedimentary records from the Arabian Sea

NASA Astrophysics Data System (ADS)

Somayajulu, B. L. K.; Yadav, D. N.; Sarin, M. M.

1994-06-01

An attempt is made to understand the redox conditions that prevailed in the north eastern continental margins of the Arabian Sea and in the nearby deep water regions during the past few centuries using short undisturbed sediment cores. The geochronology is accomplished using210Pb excess method and the proxy indicators chosen for productivity and associated redox changes are CaCO3, organic matter (OM), Mn and U along with major elements Fe and Al. Such changes in principle are related to high productivity in the overlying waters which in turn depend on monsoonal intensity that causes upwelling responsible for increase in productivity. Alongwith the published data on gravity cores from the same region, our measurements suggest the following: At ˜ 300 m water depth, south of 21°N, the sediment-water interface at depths of ˜ 300 m had been anoxic during the time span represented by the presently studied cores for approximately ˜ 700y as evidenced by low Mn/Al (< 0.7 × 10-2) and high U/Al (> 10-4) weight ratios. In some adjacent deeper regions, however, the environment turned oxic around ˜ 200 y BP. Whereas both Mn and Ra were lost to the overlying waters in the anoxic regions (depth ˜340m), the Mn that diffused from deeper sections appears to have mineralized at the sediment-water-interface. Studies of this type on long undisturbed cores from the margins of the Arabian Sea and the Bay of Bengal, involving several proxies and geochronology by more than one method are needed to understand short term environmental (and monsoonal intensity) changes of the recent past with high resolution.

Therapy-related myeloid neoplasm in an 18-year-old boy with B-lymphoblastic leukemia.

PubMed

Qing, Xin; Panosyan, Eduard; Yue, Changjun; Ji, Ping; Gotesman, Moran; French, Samuel; Cai, Junchao

2017-12-01

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Acute myeloid leukemia or myelodysplastic syndrome during the course of ALL is a rare entity. Some of these cases are therapy-related while the others occur due to lineage switch. The correct diagnosis relies on comparing the immunophenotypes and cytogenetic/molecular alterations of the myeloid neoplasm and the ALL. We present the clinical, pathologic and cytogenetic features of a case of an 18-year-old male with prior treatment for B-lymphoblastic leukemia (B-ALL) who developed therapy-related myeloid neoplasm (t-MN) 4-5years after his initial diagnosis of B-ALL. A 13-year-old boy with no significant past medical history presented to Harbor-UCLA Medical Center (HUMC) in November 2012 with night sweats, fevers and chills, nausea, vomiting, diarrhea, fatigue, weakness, and weight loss. Peripheral blood flow cytometric analysis disclosed B-ALL. The blasts expressed CD10, CD19, CD22 (dim), CD34, CD38, HLA-DR, and TdT, and were negative for CD20, CD13, CD33, CD117, and cytoplasmic MPO. Chromosomal analysis and a supplemental fluorescence in situ hybridization (FISH) study performed on the bone marrow aspirate showed an abnormal karyotype (47,XY,+X,del(9)(p21p21)[4]/46,XY[16]). He achieved remission after induction chemotherapy and remained in remission until March 2016 when bilateral testicular masses were noted. Biopsy of the left testicular mass showed relapsed B-ALL. Cerebrospinal fluid (CSF) contained rare TdT-positive blasts, suggestive of minimal/early involvement by B-ALL. However, there was no evidence of acute leukemia in his bone marrow at this time. He was then treated with COG protocol AALL1331 randomized to blinatumomab arm and achieved second remission. In June 2017, the patient's peripheral blood smear showed 11% circulating monoblasts. By flow cytometry, the blasts expressed CD4, CD11b, CD13, CD15, CD33, CD38, CD56, and CD64. In addition, a few TdT-positive blasts were seen in his CSF cytospin smear. Bone marrow biopsy was subsequently performed which was consistent with evolving acute myeloid leukemia. A diagnosis of myeloid neoplasm, consistent with t-MN was made. Chromosomal analysis and FISH studies performed on his bone marrow aspirate showed normal karyotype (46,XY[20]), negative FISH result for deletion 9p21 locus, and positive KMT2A (MLL) rearrangement, respectively. Despite of chemotherapy, the patient died within one month after diagnosis. Diagnosis of t-MN should be suspected in patients with a history of receiving cytotoxic agents and/or irradiation. In this case study, we diagnosed t-MN with KMT2A rearrangement in a patient with history of B-ALL with 9p deletion and gain of X chromosome. Unusual features associated with this case are discussed. Published by Elsevier Inc.

Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Coordinated Two-Stage Mn(II)/(III) and Mn(III)/(IV) Mechanism.

PubMed

Soldatova, Alexandra V; Romano, Christine A; Tao, Lizhi; Stich, Troy A; Casey, William H; Britt, R David; Tebo, Bradley M; Spiro, Thomas G

2017-08-23

The bacterial manganese oxidase MnxG of the Mnx protein complex is unique among multicopper oxidases (MCOs) in carrying out a two-electron metal oxidation, converting Mn(II) to MnO 2 nanoparticles. The reaction occurs in two stages: Mn(II) → Mn(III) and Mn(III) → MnO 2 . In a companion study , we show that the electron transfer from Mn(II) to the low-potential type 1 Cu of MnxG requires an activation step, likely forming a hydroxide bridge at a dinuclear Mn(II) site. Here we study the second oxidation step, using pyrophosphate (PP) as a Mn(III) trap. PP chelates Mn(III) produced by the enzyme and subsequently allows it to become a substrate for the second stage of the reaction. EPR spectroscopy confirms the presence of Mn(III) bound to the enzyme. The Mn(III) oxidation step does not involve direct electron transfer to the enzyme from Mn(III), which is shown by kinetic measurements to be excluded from the Mn(II) binding site. Instead, Mn(III) is proposed to disproportionate at an adjacent polynuclear site, thereby allowing indirect oxidation to Mn(IV) and recycling of Mn(II). PP plays a multifaceted role, slowing the reaction by complexing both Mn(II) and Mn(III) in solution, and also inhibiting catalysis, likely through binding at or near the active site. An overall mechanism for Mnx-catalyzed MnO 2 production from Mn(II) is presented.

Essential trace elements in milk and blood serum of lactating donkeys as affected by lactation stage and dietary supplementation with trace elements.

PubMed

Fantuz, F; Ferraro, S; Todini, L; Mariani, P; Piloni, R; Salimei, E

2013-11-01

The aim of this trial was to study the concentration of zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), selenium (Se), cobalt (Co) and iodine (I) in milk and blood serum of lactating donkeys, taking into account the effects of lactation stage and dietary supplementation with trace elements. During a 3-month period, 16 clinically healthy lactating donkeys (Martina-Franca-derived population), randomly divided into two homogeneous groups (control (CTL) and trace elements (TE)), were used to provide milk and blood samples at 2-week intervals. Donkeys in both groups had continuous access to meadow hay and were fed 2.5 kg of mixed feed daily, divided into two meals. The mixed feed for the TE group had the same ingredients as the CTL, but was supplemented with a commercial premix providing 163 mg Zn, 185 mg Fe, 36 mg Cu, 216 mg Mn, 0.67 mg Se, 2.78 mg Co and 3.20 mg I/kg mixed feed. The concentrations of Zn, Fe, Cu, Mn, Se, Co and I were measured in feeds, milk and blood serum by inductively coupled plasma-MS. Data were processed by ANOVA for repeated measures. The milk concentrations of all the investigated elements were not significantly affected by the dietary supplementation with TE. Serum concentrations of Zn, Fe, Cu Mn and Se were not affected by dietary treatment, but TE-supplemented donkeys showed significantly higher concentrations of serum Co (1.34 v. 0.69 μg/l) and I (24.42 v. 21.43 μg/l) than unsupplemented donkeys. The effect of lactation stage was significant for all the investigated elements in milk and blood serum, except for serum manganese. A clear negative trend during lactation was observed for milk Cu and Se concentrations (-38%), whereas that of Mn tended to increase. The serum Cu concentration was generally constant and that of Co tended to increase. If compared with data reported in the literature for human milk, donkey milk showed similarities for Zn, Mn, Co and I. Furthermore, this study indicated that, in the current experimental conditions, the mineral profile of donkey milk was not dependent on dietary TE supply.

Evaluation of trace mineral source and preharvest deletion of trace minerals from finishing diets on tissue mineral status in pigs

PubMed Central

Ma, Y. L.; Webb, S. F.; Rentfrow, G.

2018-01-01

Objective An experiment was conducted to evaluate dietary supplemental trace mineral source and deletion on mineral content in tissues. Methods Weanling crossbred pigs (n = 144; 72 barrows and 72 gilts; body weight [BW] = 7.4±1.05 kg) were used. A basal diet was prepared, and trace mineral premix containing either inorganic (ITM) or organic (OTM) trace minerals (Cu, Fe, Mn, and Zn) was added to the basal diet. Pigs were blocked by sex and BW and randomly allotted to 24 pens for a total of 6 pigs per pen, and fed a diet containing either ITM or OTM supplemented at the 1998 NRC requirement estimates for each of 5 BW phases (Phase I to V) from 7 to 120 kg. The trace mineral supplementation was deleted for 6, 4, 2, and 0 wk of Phase V; regarding nutrient adequacy during this phase, the indigenous dietary Fe and Mn was sufficient, Cu was marginal and Zn was deficient. Results At the end of Phase IV, Mn content (mg/kg on the dry matter basis) was greater (p<0.05) in heart (0.77 vs 0.68), kidney (6.32 vs 5.87), liver (9.46 vs 8.30), and longissimus dorsi (LD; 0.30 vs 0.23) of pigs fed OTM. The pigs fed OTM were greater (p<0.05) in LD Cu (2.12 vs 1.89) and Fe (21.75 vs 19.40) and metacarpal bone Zn (141.86 vs 130.05). At the end of Phase V, increased length of deletion period (from 0 to 6 wk) resulted in a decrease (linear, p<0.01) in liver Zn (196.5 to 121.8), metacarpal bone Zn (146.6 to 86.2) and an increase (linear, p<0.01) in heart Mn (0.70 to 1.08), liver Mn (7.74 to 12.96), and kidney Mn (5.58 to 7.56). The only mineral source by deletion period interaction (p<0.05) was observed in LD Zn. Conclusion The results demonstrated differential effects of mineral deletion on tissue mineral content depending on both mineral assessed and source of the mineral. PMID:28728408

Manganese (Mn) Oxidation Increases Intracellular Mn in Pseudomonas putida GB-1

PubMed Central

Banh, Andy; Chavez, Valarie; Doi, Julia; Nguyen, Allison; Hernandez, Sophia; Ha, Vu; Jimenez, Peter; Espinoza, Fernanda; Johnson, Hope A.

2013-01-01

Bacterial manganese (Mn) oxidation plays an important role in the global biogeochemical cycling of Mn and other compounds, and the diversity and prevalence of Mn oxidizers have been well established. Despite many hypotheses of why these bacteria may oxidize Mn, the physiological reasons remain elusive. Intracellular Mn levels were determined for Pseudomonas putida GB-1 grown in the presence or absence of Mn by inductively coupled plasma mass spectrometry (ICP-MS). Mn oxidizing wild type P. putida GB-1 had higher intracellular Mn than non Mn oxidizing mutants grown under the same conditions. P. putida GB-1 had a 5 fold increase in intracellular Mn compared to the non Mn oxidizing mutant P. putida GB-1-007 and a 59 fold increase in intracellular Mn compared to P. putida GB-1 ∆2665 ∆2447. The intracellular Mn is primarily associated with the less than 3 kDa fraction, suggesting it is not bound to protein. Protein oxidation levels in Mn oxidizing and non oxidizing cultures were relatively similar, yet Mn oxidation did increase survival of P. putida GB-1 when oxidatively stressed. This study is the first to link Mn oxidation to Mn homeostasis and oxidative stress protection. PMID:24147089

Manganese accumulation in hair and teeth as a biomarker of manganese exposure and neurotoxicity in rats.

PubMed

Liang, Guiqiang; Zhang, Li'e; Ma, Shuyan; Lv, Yingnan; Qin, Huiyan; Huang, Xiaowei; Qing, Li; Li, Qin; Chen, Kangcheng; Xiong, Feng; Ma, Yifei; Nong, Jie; Yang, Xiaobo; Zou, Yunfeng

2016-06-01

Manganese (Mn) is an essential trace element to humans. However, excessive Mn causes cognitive impairment resulting from injury to the central nervous system within the hippocampus. No ideal biomarker is currently available for evaluating Mn exposure and associated neurotoxicity in the body. Hence, this study used Mn levels in the serum (MnS), teeth (MnT), and hair (MnH) as biomarkers for evaluating the association between Mn exposure and cognitive impairment in Mn-treated rats. A total of 32 male Sprague-Dawley rats were randomly divided into four groups, received 0, 5, 10, and 20 mg/(kg day) of MnCl2·4H2O for 5 days a week for 18 weeks, respectively. Lifetime Mn cumulative dose (LMCD) was used to evaluate external Mn exposure. Hippocampus, serum, teeth, and hair specimens were collected from the rats for Mn determination by graphite furnace atomic absorption spectrometry. Learning and memory functions were assessed using the Morris water maze test. Results showed that chronic Mn exposure increased the hippocampus (MnHip), MnS, MnT, and MnH levels, as well as impaired learning and memory function in rats. MnHip, MnT, and MnH levels were positively correlated with LMCD (r = 0.759, r = 0.925, and r = 0.908, respectively; p < 0.05), escape latency (r = 0.862, r = 0.716, and r = 0.814, respectively; p < 0.05), and the number of platform crossings (r = -0.734, r = -0.514, and r = -0.566, respectively; p < 0.05). No association was observed between MnS levels and the number of platform crossings (r = -0.286, p > 0.05). Thus, MnT and MnH detected long-term low-dose Mn exposure. These parameters can be reliable biomarkers for Mn exposure and associated neurotoxicity in Mn-treated rats.

Pseudosymmetric fac-di­aqua­trichlorido[(di­methyl­phosphor­yl)methanaminium-κO]manganese(II)

PubMed Central

Reiss, Guido J.

2013-01-01

In the title compound, [Mn(C3H11NOP)Cl3(H2O)2], the MnII metal center has a distorted o­cta­hedral geometry, coordinated by the three chloride ligands showing a facial arrangement. Two water mol­ecules and the O-coordinated dpmaH cation [dpmaH = (di­methyl­phosphor­yl)methanaminium] complete the coordination sphere. Each complex mol­ecule is connected to its neighbours by O—H⋯Cl and N—H⋯Cl hydrogen bonds. Two of the chloride ligands and the two water ligands form a hydrogen-bonded polymeric sheet in the ab plane. Furthermore, these planes are connected to adjacent planes by hydrogen bonds from the aminium function of cationic dpmaH ligand. A pseudo-mirror plane perpendicular to the b axis in the chiral space group P21 is observed together with inversion twinning [ratio = 0.864 (5):0.136 (5)]. PMID:23723764

Mineral composition of durum wheat grain and pasta under increasing atmospheric CO2 concentrations.

PubMed

Beleggia, Romina; Fragasso, Mariagiovanna; Miglietta, Franco; Cattivelli, Luigi; Menga, Valeria; Nigro, Franca; Pecchioni, Nicola; Fares, Clara

2018-03-01

The concentrations of 10 minerals were investigated in the grain of 12 durum wheat genotypes grown under free air CO 2 enrichment conditions, and in four of their derived pasta samples, using inductively coupled plasma mass spectrometry. Compared to ambient CO 2 (400ppm; AMB), under elevated CO 2 (570ppm; ELE), the micro-element and macro-element contents showed strong and significant decreases in the grain: Mn, -28.3%; Fe, -26.7%; Zn, -21.9%; Mg, -22.7%; Mo, -40.4%; K, -22.4%; and Ca, -19.5%. These variations defined the 12 genotypes as sensitive or non-sensitive to ELE. The pasta samples under AMB and ELE showed decreased mineral contents compared to the grain. Nevertheless, the contributions of the pasta to the recommended daily allowances remained relevant, also for the micro-elements under ELE conditions (range, from 18% of the recommended daily allowance for Zn, to 70% for Mn and Mo). Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical hydrogen storage alloys and batteries fabricated from Mg containing base alloys

DOEpatents

Ovshinsky, Stanford R.; Fetcenko, Michael A.

1996-01-01

An electrochemical hydrogen storage material comprising: (Base Alloy).sub.a M.sub.b where, Base Alloy is an alloy of Mg and Ni in a ratio of from about 1:2 to about 2:1, preferably 1:1; M represents at least one modifier element chosen from the group consisting of Co, Mn, Al, Fe, Cu, Mo, W, Cr, V, Ti, Zr, Sn, Th, Si, Zn, Li, Cd, Na, Pb, La, Mm, and Ca; b is greater than 0.5, preferably 2.5, atomic percent and less than 30 atomic percent; and a+b=100 atomic percent. Preferably, the at least one modifier is chosen from the group consisting of Co, Mn, Al, Fe, and Cu and the total mass of the at least one modifier element is less than 25 atomic percent of the final composition. Most preferably, the total mass of said at least one modifier element is less than 20 atomic percent of the final composition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ari-Gur, Pnina; Garlea, Vasile O.; Cao, Huibo

In this study, Heusler alloys of Ni-Mn-Ga compositions demonstrate ferromagnetic shape memory effect in the martensitic state. The transformation temperature and the chemical order depend strongly on the composition. In the current work, the structure and chemical order of the martensitic phase of Ni 1.91Mn 1.29Ga 0.8 were studied using neutron diffraction; the diffraction pattern was refined using the FullProf software. It was determined that the structural transition occurs around 330 K. At room temperature, 300 K, which is below the martensite transformation temperature, all the Bragg reflections can be described by a monoclinic lattice with a symmetry of spacemore » group P 1 2/m 1 and lattice constants of a = 4.23047(7) [Å], b = 5.58333(6) [Å], c = 21.0179(2) [Å], beta = 90.328(1). The chemical order is of critical importance in these alloys, and it was previously studied at 363 K. Analysis of the neutron diffraction in the monoclinic phase shows that the chemical order is maintained during the martensitic transformation.« less

Plumboan crichtonite: from the Fazenda Guariba, Minas Gerais, Brazil

USGS Publications Warehouse

Foord, E.E.; Chaves, M.L.D.S.C.; Lichte, F.E.

1994-01-01

Senaite, Pb(Ti,Fe,Mn)21O38, a member of the crichtonite group, was first described from alluvial gravels near Dattas, Minas Gerais, Brazil. It was subsequently reported (always from alluvial stream gravels) from about seven additional localities. "Senaite' from the first in situ source in Brazil, at the Fazenda Guariba, Minas Gerais, Brazil was described by Cassedanne (1988). Approximately 20 crystals of "senaite' from the Fazenda Guariba were examined chemically and all were found to be plumboan crichtonite rather than senaite. -from Authors

Critical Review and Technology Assessments, 󈨟-󈨠

DTIC Science & Technology

1991-09-01

EUTELCIC ALLOY 3. Pages 406-409 890900 WATER SORPTION IN EPOXY THIN FILMS MCMASTER, M.G. UC, ,ERKELEY.CA) TRANSACTIONS. 89.22 SOANE, Di. ,EEEJHMT. Vol...NATION, 21 228-002 PENETRATION THROUGH PFA TUBING AND Vol. S, No. 2, Pags ANTISTATIC PFATUBING 22-28 THIS COLUMN FOCUSES ON A STUIDY OF PFA AND...ANTISTATIC WFA TURING (SUPPLIED BY GALnlEK CORPORATION. CHAS•K MN). THE A.NTISATIC PFA .MATERIAL USED HAS A SURFACE RESISTIVIrY OF lOTO THE ELEVENTH POWER -10

Develop Techniques for Ion Implantation of PLZT for Adaptive Optics

DTIC Science & Technology

1989-11-01

WL-TR-89-26 FIGURES (Continued) Fizure Page 20 EDX elemental spectrum from perovskite region of the sample shown in Fig. 15. 65 21 EDX elemental...pyroelectric response. 126 84 Result of doping PZT with La and Mn (Ref. 7). 127 85 APW results along the lin for several perovskite - type compounds and ReO 2...structure of the calcined powder was analyzed and shown to be mainly the hexagonal/rhombohedral phase within 17 WL-TR-89-26 the perovskite structure of

Artificial Neural Network Prediction of Chemical-Disease Relationships using Readily Available Chemical Properties

DTIC Science & Technology

2014-03-27

C15H13N3O4S Potassium Bromide 0119000100 BrK Potassium Permanganate 0158030400 MnO4K Prazosin 0383410801 C19H21N5O4 Propranolol-HCl 0259350302...chemicals and correctly match it to a single disease category. Potassium permanganate and ethylene glycol can both be correctly linked to disease group...chemical is linked to the same disease, the network is unable to predict the same disease for the multiple chemicals. Potassium permanganate and

Crystal and magnetic structure of the La1-xCaxMnO3 compound (0.11⩽x⩽0.175)

NASA Astrophysics Data System (ADS)

Pissas, M.; Margiolaki, I.; Papavassiliou, G.; Stamopoulos, D.; Argyriou, D.

2005-08-01

We studied the crystal and magnetic structure of the La1-xCaxMnO3 compound for (0.11⩽x⩽0.175) using stoichiometric samples. For x<0.13 the system’s ground state is insulating canted antiferromagnetic. For 0.13⩽x⩽0.175 below the Jahn-Teller transition temperature (TJT) the crystal structure undergoes a monoclinic distortion. The crystal structure can be described with P21/c space group which permits two Mn sites. The unit-cell strain parameter s=2(a-c)/(a+c) increases for Ta>b/2) structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmitt, Adam K.; Mahanthappa, Mahesh K.

Using a combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), we document the composition-dependent morphologies of 39 new poly(lactide-block-1,4-butadiene-block-lactide) (LBL) block polymers, comprising a broad dispersity B segment (Mn = 4.5–17.7 kg/mol;more » $$\\def\\eth{{\\specialfont\\char238}}$$ = Mw/Mn = 1.72–1.88) and narrow dispersity L end blocks (Mn = 0.6–15.3 kg/mol; $$\\def\\eth{{\\specialfont\\char238}}$$ = 1.10–1.21) with volume fractions 0.26 ≤ fB ≤ 0.95. A subset of these samples undergo melt self-assembly into cylindrical, lamellar, and apparently bicontinuous morphologies. By assessing the states of order and disorder in these triblock polymer melts using temperature-dependent SAXS, we find that broad B segment dispersity increases the minimum segregation strength χN ≳ 27 required for LBL triblock self-assembly relative to the self-consistent mean-field theory prediction χN ≥ 17.9 for narrow dispersity analogues. While B segment dispersity has previously been shown to thermodynamically stabilize the self-assembled morphologies of low χ/high N ABA triblocks, the present study indicates that broad B block dispersity in related high χ/low N systems destabilizes the microphase-separated melt. These observations are rationalized in terms of recent theories that suggest that broad segmental dispersity substantially enhances fluctuation effects at low N, thus disfavoring melt segregation.« less

B a 2 NiOs O 6 : A Dirac-Mott insulator with ferromagnetism near 100 K

DOE PAGES

Feng, Hai L.; Calder, Stuart; Ghimire, Madhav Prasad; ...

2016-12-28

In this study, the ferromagnetic semiconductor Ba 2NiOsO 6 ( T mag ~ 100 K ) was synthesized at 6 GPa and 1500 °C. It crystallizes into a double perovskite structure [Fm - 3m ; a = 8.0428 ( 1 ) Å], where the Ni 2+ and Os 6+ ions are perfectly ordered at the perovskite B site. We show that the spin-orbit coupling of Os 6+ plays an essential role in opening the charge gap. The magnetic state was investigated by density functional theory calculations and powder neutron diffraction. The latter revealed a collinear ferromagnetic order in a >more » 21 kOe magnetic field at 5 K. The ferromagnetic gapped state is fundamentally different from that of known dilute magnetic semiconductors such as (Ga,Mn)As and (Cd,Mn)Te ( T mag < 180 K ), the spin-gapless semiconductor Mn 2 CoAl ( T mag ~ 720 K ), and the ferromagnetic insulators EuO ( T mag ~ 70 K ) and Bi 3Cr 3O 11 ( T mag ~ 220 K ). It is also qualitatively different from known ferrimagnetic insulators and semiconductors, which are characterized by an antiparallel spin arrangement. Our finding of the ferromagnetic semiconductivity of Ba 2NiOsO 6 should increase interest in the platinum group oxides, because this alternative class of materials should be useful in the development of spintronic, quantum magnetic, and related devices.« less

B a 2 NiOs O 6 : A Dirac-Mott insulator with ferromagnetism near 100 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Hai L.; Calder, Stuart; Ghimire, Madhav Prasad

In this study, the ferromagnetic semiconductor Ba 2NiOsO 6 ( T mag ~ 100 K ) was synthesized at 6 GPa and 1500 °C. It crystallizes into a double perovskite structure [Fm - 3m ; a = 8.0428 ( 1 ) Å], where the Ni 2+ and Os 6+ ions are perfectly ordered at the perovskite B site. We show that the spin-orbit coupling of Os 6+ plays an essential role in opening the charge gap. The magnetic state was investigated by density functional theory calculations and powder neutron diffraction. The latter revealed a collinear ferromagnetic order in a >more » 21 kOe magnetic field at 5 K. The ferromagnetic gapped state is fundamentally different from that of known dilute magnetic semiconductors such as (Ga,Mn)As and (Cd,Mn)Te ( T mag < 180 K ), the spin-gapless semiconductor Mn 2 CoAl ( T mag ~ 720 K ), and the ferromagnetic insulators EuO ( T mag ~ 70 K ) and Bi 3Cr 3O 11 ( T mag ~ 220 K ). It is also qualitatively different from known ferrimagnetic insulators and semiconductors, which are characterized by an antiparallel spin arrangement. Our finding of the ferromagnetic semiconductivity of Ba 2NiOsO 6 should increase interest in the platinum group oxides, because this alternative class of materials should be useful in the development of spintronic, quantum magnetic, and related devices.« less

Levels of Essential Elements in Different Medicinal Plants Determined by Using Inductively Coupled Plasma Mass Spectrometry

PubMed Central

2018-01-01

The objective of this study was to investigate the content of essential elements in medicinal plants in the Kingdom of Saudi Arabia (KSA). Five different medical plants (mahareeb (Cymbopogon schoenanthus), sheeh (Artemisia vulgaris), harjal (Cynanchum argel delile), nabipoot (Equisetum arvense), and cafmariam (Vitex agnus-castus)) were collected from Madina city in the KSA. Five elements Fe, Mn, Zn, Cu, and Se were determined by using inductively coupled plasma mass spectrometry (ICP-MS). Fe levels were the highest and Se levels were the lowest in all plants. The range levels of all elements in all plants were as follows: Fe 193.4–1757.9, Mn 23.6–143.7, Zn 15.4–32.7, Se 0.13–0.92, and Cu 11.3–21.8 µg/g. Intakes of essential elements from the medical plants in infusion were calculated: Fe 4.6–13.4, Mn 6.7–123.2, Zn 7.0–42.7, Se 0.14–1.5, and Cu 1.5–5.0 µg/dose. The calculated intakes of essential elements for all plants did not exceed the daily intake set by the World Health Organization (WHO) and European Food Safety Authority (EFSA). These medicinal plants may be useful sources of essential elements, which are vital for health. PMID:29744234

Zn-Mn alloy coatings from acidic chloride bath: Effect of deposition conditions on the Zn-Mn electrodeposition-morphological and structural characterization

NASA Astrophysics Data System (ADS)

Loukil, N.; Feki, M.

2017-07-01

Zn-Mn alloy electrodeposition on steel electrode in chloride bath was investigated using cyclic voltammetric, chronopotentiometric and chronoamperometric techniques. Cyclic voltammetries (CV) reveal a deep understanding of electrochemical behaviors of each metal Zn, Mn, proton discharge and Zn-Mn co-deposition. The electrochemical results show that with increasing Mn2+ ions concentration in the electrolytic bath, Mn2+ reduction occurs at lower over-potential leading to an enhancement of Mn content into the Zn-Mn deposits. A dimensionless graph model was used to analyze the effect of Mn2+ ions concentration on Zn-Mn nucleation process. It was found that the nucleation process is not extremely affected by Mn2+ concentration. Nevertheless, it significantly depends on the applied potential. Several parameters such as Mn2+ ions concentration, current density and stirring were investigated with regard to the Mn content into the final Zn-Mn coatings. It was found that the Mn content increases with increasing the applied current density jimp and Mn2+ ions concentration in the electrolytic bath. However, stirring of the solution decreases the Mn content in the Zn-Mn coatings. The phase structure and surface morphology of Zn-Mn deposits are characterized by means of X-ray diffraction analysis and Scanning Electron Microscopy (SEM), respectively. The Zn-Mn deposited at low current density is tri-phasic and consisting of η-Zn, ζ-MnZn13 and hexagonal close packed ε-Zn-Mn. An increase in current density leads to a transition from crystalline to amorphous structure, arising from the hydroxide inclusions in the Zn-Mn coating at high current density.

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al-5Mg-Mn Alloys Solidified Under Near-Rapid Cooling.

PubMed

Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

2016-01-29

Mn was an important alloying element used in Al-Mg-Mn alloys. However, it had to be limited to a low level (<1.0 wt %) to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al-5Mg-Mn alloy with low Fe content (<0.1 wt %), intermetallic Al₆(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al₆(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al-5Mg-Mn alloys (0.5 wt % Fe), intermetallic Al₆(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al₆(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al₆(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al₆(Fe,Mn) to become the primary phase at a lower Mn content.

[Chemical forms and ecological effect of soil Mn in liver cancer's high incidence area in Zhu-jiang River Delta, China].

PubMed

Dou, Lei; Zhou, Yong-Zhang; Li, Yong; Ma, Jin; An, Yan-Fei; Du, Hai-Yan; Li, Zhan-Qiang

2008-06-01

The samples of surface soil, deep soil, and vegetables were collected from the liver cancer's high- and low incidence areas in Zhujiang River Delta to study the relationships between soil Mn forms and vegetables' Mn enrichment. The results showed that the soil Mn in study area was mainly derived from parent materials, and rarely come from human activities. The average soil Mn content in liver cancer's high incidence area was 577.65 mg x kg(-1), being significantly lower than that of liver cancer's low incidence area (718.04 mg x kg(-1)) and whole country (710 mg x kg(-1)). The Mn forms in high incidence area were mainly of residual Mn and Fe-Mn oxide, and less of water soluble Mn and exchangeable Mn, with the sum of the latter two's distribution coefficients being not higher than 4%. In low incidence area, the distribution pattern of soil Mn forms was similar to that in high incidence area, but the absolute contents of the Mn forms were significantly higher. Soil total Mn and soil pH had significant effects on soil Mn forms. There existed significant positive correlations between soil total Mn and the Mn forms of Fe-Mn bound, humic acid bound, carbonate bound, and residual, and negative correlations between soil pH and soil water soluble and organic bound Mn forms. Among the test five kinds of vegetables, Youmai lettuce and Chinese cabbage in liver cancer' s high incidence area had a significantly lower Mn content than in low incidence area, while the other three had less difference. The Mn enrichment in test vegetables was positively correlated with to the content of soil available Mn (sum of water soluble Mn and exchangeable Mn), but had no correlations with the contents of soil total Mn and other Mn forms.

Nano-sized Mn3O4 and β-MnOOH from the decomposition of β-cyclodextrin-Mn: 2. The water-oxidizing activities.

PubMed

Najafpour, Mohammad Mahdi; Mostafalu, Ramin; Hołyńska, Małgorzata; Ebrahimi, Foad; Kaboudin, Babak

2015-11-01

Nano-sized Mn oxides contain Mn3O4, β-MnOOH and Mn2O3 have been prepared by a previously reported method using thermal decomposition of β-cyclodextrin-Mn complexes. In the next step, the water-oxidizing activities of these Mn oxides using cerium(IV) ammonium nitrate as a chemical oxidant are studied. The turnover frequencies for β-MnO(OH) and Mn3O4 are 0.24 and 0.01-0.17 (mmol O2/mol Mns), respectively. Subsequently, water-oxidizing activities of these compounds are compared to the other previously reported Mn oxides. Important factors affecting water oxidation by these Mn oxides are also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Arsenite Oxidation by a Poorly-Crystalline Manganese Oxide 2. Results from X-ray Absorption Spectroscopy and X-ray Diffraction

PubMed Central

Lafferty, Brandon J.; Ginder-Vogel, Matthew; Zhu, Mengqiang; Livi, Kenneth J. T.; Sparks, Donald L.

2010-01-01

Arsenite (AsIII) oxidation by manganese oxides (Mn-oxides) serves to detoxify and, under many conditions, immobilize arsenic (As) by forming arsenate (AsV). AsIII oxidation by MnIV-oxides can be quite complex, involving many simultaneous forward reactions and subsequent back reactions. During AsIII oxidation by Mn-oxides, a reduction in oxidation rate is often observed, which is attributed to Mn-oxide surface passivation. X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) data show that MnII sorption on a poorly-crystalline hexagonal birnessite (δ-MnO2) is important in passivation early during reaction with AsIII. Also, it appears that MnIII in the δ-MnO2 structure is formed by conproportionation of sorbed MnII and MnIV in the mineral structure. The content of MnIII within the δ-MnO2 structure appears to increase as the reaction proceeds. Binding of AsV to δ-MnO2 also changes as MnIII becomes more prominent in the δ-MnO2 structure. The data presented indicate that AsIII oxidation and AsV sorption by poorly-crystalline δ-MnO2 is greatly affected by Mn oxidation state in the δ-MnO2 structure. PMID:20977204

Assessment of saliva, hair and toenails as biomarkers of low level exposure to manganese from drinking water in children.

PubMed

Ntihabose, Ruth; Surette, Céline; Foucher, Delphine; Clarisse, Olivier; Bouchard, Maryse F

2018-01-01

We evaluated hair, toenails, and saliva (whole and supernatant) as biomarkers of exposure to manganese (Mn) in 274 school age children (6-13 years) consuming well water in southeastern New Brunswick, Canada. Mn concentrations in tap water ranged from <0.03 to 1046μgL -1 (geometric mean 5.96μgL -1 ). The geometric mean of Mn intake resulting from the consumption of water was 0.25 (0-34.95) μg kg -1 day -1 . Both Mn concentration in water and Mn intake were significantly correlated with Mn in hair (r=0.60 and r=0.53, respectively), Mn in toenail (r=0.29 and r=0.37 respectively) and to a lesser extent with Mn in saliva supernatant (r=0.14 and r=0.18, respectively). Mn in whole saliva did not correlate with Mn in water or Mn intake. Both Mn in hair and Mn in toenail allowed to discriminate the most exposed group from the least exposed group, based on Mn in water and Mn intake from water. In this group of children with low level Mn exposure, Mn concentrations in hair, and toenails reflected reasonably well Mn exposure from drinking water, whereas Mn content in saliva correlated less strongly. Copyright © 2017 Elsevier B.V. All rights reserved.

Theoretical investigation of the reaction of Mn+ with ethylene oxide.

PubMed

Li, Yuanyuan; Guo, Wenyue; Zhao, Lianming; Liu, Zhaochun; Lu, Xiaoqing; Shan, Honghong

2012-01-12

The potential energy surfaces of Mn(+) reaction with ethylene oxide in both the septet and quintet states are investigated at the B3LYP/DZVP level of theory. The reaction paths leading to the products of MnO(+), MnO, MnCH(2)(+), MnCH(3), and MnH(+) are described in detail. Two types of encounter complexes of Mn(+) with ethylene oxide are formed because of attachments of the metal at different sites of ethylene oxide, i.e., the O atom and the CC bond. Mn(+) would insert into a C-O bond or the C-C bond of ethylene oxide to form two different intermediates prior to forming various products. MnO(+)/MnO and MnH(+) are formed in the C-O activation mechanism, while both C-O and C-C activations account for the MnCH(2)(+)/MnCH(3) formation. Products MnO(+), MnCH(2)(+), and MnH(+) could be formed adiabatically on the quintet surface, while formation of MnO and MnCH(3) is endothermic on the PESs with both spins. In agreement with the experimental observations, the excited state a(5)D is calculated to be more reactive than the ground state a(7)S. This theoretical work sheds new light on the experimental observations and provides fundamental understanding of the reaction mechanism of ethylene oxide with transition metal cations.

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

PubMed Central

Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

2016-01-01

Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (<1.0 wt %) to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al–5Mg–Mn alloy with low Fe content (<0.1 wt %), intermetallic Al6(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe), intermetallic Al6(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn) to become the primary phase at a lower Mn content. PMID:28787888

Synchrotron-Based Techniques Shed Light on Mechanisms of Plant Sensitivity and Tolerance to High Manganese in the Root Environment.

PubMed

Blamey, F Pax C; Hernandez-Soriano, Maria C; Cheng, Miaomiao; Tang, Caixian; Paterson, David J; Lombi, Enzo; Wang, Wei Hong; Scheckel, Kirk G; Kopittke, Peter M

2015-11-01

Plant species differ in response to high available manganese (Mn), but the mechanisms of sensitivity and tolerance are poorly understood. In solution culture, greater than or equal to 30 µm Mn decreased the growth of soybean (Glycine max), but white lupin (Lupinus albus), narrow-leafed lupin (Lupin angustifolius), and sunflower (Helianthus annuus) grew well at 100 µm Mn. Differences in species' tolerance to high Mn could not be explained simply by differences in root, stem, or leaf Mn status, being 8.6, 17.1, 6.8, and 9.5 mmol kg(-1) leaf fresh mass at 100 µm Mn. Furthermore, x-ray absorption near edge structure analyses identified the predominance of Mn(II), bound mostly to malate or citrate, in roots and stems of all four species. Rather, differences in tolerance were due to variations in Mn distribution and speciation within leaves. In Mn-sensitive soybean, in situ analysis of fresh leaves using x-ray fluorescence microscopy combined with x-ray absorption near edge structure showed high Mn in the veins, and manganite [Mn(III)] accumulated in necrotic lesions apparently through low Mn sequestration in vacuoles or other vesicles. In the two lupin species, most Mn accumulated in vacuoles as either soluble Mn(II) malate or citrate. In sunflower, Mn was sequestered as manganite at the base of nonglandular trichomes. Hence, tolerance to high Mn was ascribed to effective sinks for Mn in leaves, as Mn(II) within vacuoles or through oxidation of Mn(II) to Mn(III) in trichomes. These two mechanisms prevented Mn accumulation in the cytoplasm and apoplast, thereby ensuring tolerance to high Mn in the root environment. © 2015 American Society of Plant Biologists. All Rights Reserved.

Synchrotron-Based Techniques Shed Light on Mechanisms of Plant Sensitivity and Tolerance to High Manganese in the Root Environment1[OPEN

PubMed Central

Blamey, F. Pax C.; Hernandez-Soriano, Maria C.; Cheng, Miaomiao; Tang, Caixian; Paterson, David J.; Lombi, Enzo; Wang, Wei Hong; Scheckel, Kirk G.; Kopittke, Peter M.

2015-01-01

Plant species differ in response to high available manganese (Mn), but the mechanisms of sensitivity and tolerance are poorly understood. In solution culture, greater than or equal to 30 µm Mn decreased the growth of soybean (Glycine max), but white lupin (Lupinus albus), narrow-leafed lupin (Lupin angustifolius), and sunflower (Helianthus annuus) grew well at 100 µm Mn. Differences in species’ tolerance to high Mn could not be explained simply by differences in root, stem, or leaf Mn status, being 8.6, 17.1, 6.8, and 9.5 mmol kg–1 leaf fresh mass at 100 µm Mn. Furthermore, x-ray absorption near edge structure analyses identified the predominance of Mn(II), bound mostly to malate or citrate, in roots and stems of all four species. Rather, differences in tolerance were due to variations in Mn distribution and speciation within leaves. In Mn-sensitive soybean, in situ analysis of fresh leaves using x-ray fluorescence microscopy combined with x-ray absorption near edge structure showed high Mn in the veins, and manganite [Mn(III)] accumulated in necrotic lesions apparently through low Mn sequestration in vacuoles or other vesicles. In the two lupin species, most Mn accumulated in vacuoles as either soluble Mn(II) malate or citrate. In sunflower, Mn was sequestered as manganite at the base of nonglandular trichomes. Hence, tolerance to high Mn was ascribed to effective sinks for Mn in leaves, as Mn(II) within vacuoles or through oxidation of Mn(II) to Mn(III) in trichomes. These two mechanisms prevented Mn accumulation in the cytoplasm and apoplast, thereby ensuring tolerance to high Mn in the root environment. PMID:26395840

Dietary Manganese Modulates PCB126 Toxicity, Metal Status, and MnSOD in the Rat

PubMed Central

Wang, Bingxuan; Klaren, William D.; Wels, Brian R.; Simmons, Donald L.; Olivier, Alicia K.; Wang, Kai; Robertson, Larry W.; Ludewig, Gabriele

2016-01-01

PCB126 (3,3′,4,4′,5-pentachlorobiphenyl) is a potent aryl hydrocarbon receptor agonist and induces oxidative stress. Because liver manganese (Mn) levels decrease in response to PCB126, a Mn dietary study was designed to investigate the role of Mn in PCB126 toxicity. Male Sprague Dawley rats received diets containing 0, 10, or 150 ppm added Mn for 3 weeks, followed by a single ip injection of corn oil or PCB126 (5 µmol/kg body weight). After 2 weeks, Mn, Cu, Zn, and Fe levels in the heart, liver, and liver mitochondria, and Mn-containing superoxide dismutase (MnSOD) and metallothionein mRNA, MnSOD protein, and MnSOD activity were determined. Mn levels in liver, heart, and liver mitochondria were strongly decreased by the Mn-deficient diet. Small effects on Fe levels and a stepwise increase in MnSOD activity with dietary Mn were also visible. PCB126 caused profound changes in Cu (up), Zn, Fe, and Mn (down) in liver, but not in heart, and differing effects (Cu, Zn, and Fe up, Mn down) in liver mitochondria. Liver MnSOD and metallothionein mRNA levels and MnSOD protein were increased but MnSOD activity was decreased by PCB126. PCB126-induced liver enlargement was dose-dependently reduced with increasing dietary Mn. These changes in metals homeostasis and MnSOD activity in liver but not heart may be a/the mechanism of PCB126 liver-specific toxicity. Specifically, transport of Fenton metals (Cu, Fe) into and Mn out of the mitochondria, a probable mechanism for lower MnSOD activity, may be a/the cause of PCB126-induced oxidative stress. The role of metallothioneins needs further evaluation. Dietary Mn slightly alleviated PCB126-induced toxicities. PMID:26660635

Structural response of phyllomanganates to wet aging and aqueous Mn(II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinkle, Margaret A. G.; Flynn, Elaine D.; Catalano, Jeffrey G.

Naturally occurring Mn(IV/III) oxides are often formed through microbial Mn(II) oxidation, resulting in reactive phyllomanganates with varying Mn(IV), Mn(III), and vacancy contents. Residual aqueous Mn(II) may adsorb in the interlayer of phyllomanganates above vacancies in their octahedral sheets. The potential for interlayer Mn(II)-layer Mn(IV) comproportionation reactions and subsequent formation of structural Mn(III) suggests that aqueous Mn(II) may cause phyllomanganate structural changes that alters mineral reactivity or trace metal scavenging. Here we examine the effects of aging phyllomanganates with varying initial vacancy and Mn(III) content in the presence and absence of dissolved Mn(II) at pH 4 and 7. Three phyllomanganates weremore » studied: two exhibiting turbostratic layer stacking (δ-MnO2 with high vacancy content and hexagonal birnessite with both vacancies and Mn(III) substitutions) and one with rotationally ordered layer stacking (triclinic birnessite containing predominantly Mn(III) substitutions). Structural analyses suggest that during aging at pH 4, Mn(II) adsorbs above vacancies and promotes the formation of phyllomanganates with rotationally ordered sheets and mixed symmetries arranged into supercells, while structural Mn(III) undergoes disproportionation. These structural changes at pH 4 correlate with reduced Mn(II) uptake onto triclinic and hexagonal birnessite after 25 days relative to 48 h of reaction, indicating that phyllomanganate reactivity decreases upon aging with Mn(II), or that recrystallization processes involving Mn(II) uptake occur over 25 days. At pH 7, Mn(II) adsorbs and causes limited structural effects, primarily increasing sheet stacking in δ-MnO2. These results show that aging-induced structural changes in phyllomanganates are affected by aqueous Mn(II), pH, and initial solid-phase Mn(III) content. In conclusion, such restructuring likely alters manganese oxide reactions with other constituents in environmental and geologic systems, particularly trace metals and redox-active compounds.« less

A Comparison of Two Yeast MnSODs: Mitochondrial Saccharomyces cerevisiae versus Cytosolic Candida albicans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng Y.; Cabelli D.; Stich, T.A.

Human MnSOD is significantly more product-inhibited than bacterial MnSODs at high concentrations of superoxide (O{sub 2}{sup -}). This behavior limits the amount of H{sub 2}O{sub 2} produced at high [O{sub 2}{sup -}]; its desirability can be explained by the multiple roles of H{sub 2}O{sub 2} in mammalian cells, particularly its role in signaling. To investigate the mechanism of product inhibition in MnSOD, two yeast MnSODs, one from Saccharomyces cerevisiae mitochondria (ScMnSOD) and the other from Candida albicans cytosol (CaMnSODc), were isolated and characterized. ScMnSOD and CaMnSODc are similar in catalytic kinetics, spectroscopy, and redox chemistry, and they both rest predominantlymore » in the reduced state (unlike most other MnSODs). At high [O{sub 2}{sup -}], the dismutation efficiencies of the yeast MnSODs surpass those of human and bacterial MnSODs, due to very low level of product inhibition. Optical and parallel-mode electron paramagnetic resonance (EPR) spectra suggest the presence of two Mn{sup 3+} species in yeast Mn{sup 3+}SODs, including the well-characterized 5-coordinate Mn{sup 3+} species and a 6-coordinate L-Mn{sup 3+} species with hydroxide as the putative sixth ligand (L). The first and second coordination spheres of ScMnSOD are more similar to bacterial than to human MnSOD. Gln154, an H-bond donor to the Mn-coordinated solvent molecule, is slightly further away from Mn in yeast MnSODs, which may result in their unusual resting state. Mechanistically, the high efficiency of yeast MnSODs could be ascribed to putative translocation of an outer-sphere solvent molecule, which could destabilize the inhibited complex and enhance proton transfer from protein to peroxide. Our studies on yeast MnSODs indicate the unique nature of human MnSOD in that it predominantly undergoes the inhibited pathway at high [O{sub 2}{sup -}].« less

A Comparison of Two Yeast MnSODs: Mitochondrial Saccharomyces cerevisiae versus Cytosolic Candida albicans

PubMed Central

Sheng, Yuewei; Stich, Troy A.; Barnese, Kevin; Gralla, Edith B.; Cascio, Duilio; Britt, R. David; Cabelli, Diane E.; Valentine, Joan Selverstone

2011-01-01

Human MnSOD is significantly more product-inhibited than bacterial MnSODs at high concentrations of superoxide (O2−). This behavior limits the amount of H2O2 produced at high [O2−]; its desirability can be explained by the multiple roles of H2O2 in mammalian cells, particularly its role in signaling. To investigate the mechanism of product inhibition in MnSOD, two yeast MnSODs, one from Saccharomyces cerevisiae mitochondria (ScMnSOD) and the other from Candida albicans cytosol (CaMnSODc), were isolated and characterized. ScMnSOD and CaMnSODc are similar in catalytic kinetics, spectroscopy and redox chemistry, and they both rest predominantly in the reduced state (unlike most other MnSODs). At high [O2−] the dismutation efficiencies of the yeast MnSODs surpass those of human and bacterial MnSODs, due to very low level of product inhibition. Optical and parallel-mode electron paramagnetic resonance (EPR) spectra suggest the presence of two Mn3+ species in yeast Mn3+SODs, including the well-characterized 5-coordinate Mn3+ species and a 6-coordinate L-Mn3+ species with hydroxide as the putative sixth ligand (L). The first and second coordination spheres of ScMnSOD are more similar to bacterial than to human MnSOD. Gln154, an H-bond donor to the Mn-coordinated solvent molecule, is slightly further away from Mn in yeast MnSODs, which may result in their unusual resting state. Mechanistically, the high efficiency of yeast MnSODs could be ascribed to putative translocation of an outer-sphere solvent molecule, which could destabilize the inhibited complex and enhance proton transfer from protein to peroxide. Our studies on yeast MnSODs indicate the unique nature of human MnSOD in that it predominantly undergoes the inhibited pathway at high [O2−]. PMID:22077216

Structural response of phyllomanganates to wet aging and aqueous Mn(II)

DOE PAGES

Hinkle, Margaret A. G.; Flynn, Elaine D.; Catalano, Jeffrey G.

2016-08-06

Naturally occurring Mn(IV/III) oxides are often formed through microbial Mn(II) oxidation, resulting in reactive phyllomanganates with varying Mn(IV), Mn(III), and vacancy contents. Residual aqueous Mn(II) may adsorb in the interlayer of phyllomanganates above vacancies in their octahedral sheets. The potential for interlayer Mn(II)-layer Mn(IV) comproportionation reactions and subsequent formation of structural Mn(III) suggests that aqueous Mn(II) may cause phyllomanganate structural changes that alters mineral reactivity or trace metal scavenging. Here we examine the effects of aging phyllomanganates with varying initial vacancy and Mn(III) content in the presence and absence of dissolved Mn(II) at pH 4 and 7. Three phyllomanganates weremore » studied: two exhibiting turbostratic layer stacking (δ-MnO2 with high vacancy content and hexagonal birnessite with both vacancies and Mn(III) substitutions) and one with rotationally ordered layer stacking (triclinic birnessite containing predominantly Mn(III) substitutions). Structural analyses suggest that during aging at pH 4, Mn(II) adsorbs above vacancies and promotes the formation of phyllomanganates with rotationally ordered sheets and mixed symmetries arranged into supercells, while structural Mn(III) undergoes disproportionation. These structural changes at pH 4 correlate with reduced Mn(II) uptake onto triclinic and hexagonal birnessite after 25 days relative to 48 h of reaction, indicating that phyllomanganate reactivity decreases upon aging with Mn(II), or that recrystallization processes involving Mn(II) uptake occur over 25 days. At pH 7, Mn(II) adsorbs and causes limited structural effects, primarily increasing sheet stacking in δ-MnO2. These results show that aging-induced structural changes in phyllomanganates are affected by aqueous Mn(II), pH, and initial solid-phase Mn(III) content. In conclusion, such restructuring likely alters manganese oxide reactions with other constituents in environmental and geologic systems, particularly trace metals and redox-active compounds.« less

The bioavailability of manganese in welders in relation to its solubility in welding fumes.

PubMed

Ellingsen, Dag G; Zibarev, Evgenij; Kusraeva, Zarina; Berlinger, Balazs; Chashchin, Maxim; Bast-Pettersen, Rita; Chashchin, Valery; Thomassen, Yngvar

2013-02-01

Blood and urine samples for determination of manganese (Mn) and iron (Fe) concentrations were collected in a cross-sectional study of 137 currently exposed welders, 137 referents and 34 former welders. Aerosol samples for measurements of personal air exposure to Mn and Fe were also collected. The aerosol samples were assessed for their solubility using a simulated lung lining fluid (Hatch solution). On average 13.8% of the total Mn mass (range 1-49%; N = 237) was soluble (Hatch sol), while only 1.4% (<0.1-10.0%; N = 237) of the total Fe mass was Hatch sol. The welders had statistically significantly higher geometric mean concentrations of Mn in whole blood (B-Mn 12.8 vs. 8.0 μg L (-1)), serum (S-Mn 1.04 vs. 0.77 μg L(-1)) and urine (U-Mn 0.36 vs. 0.07 μg g (-1) cr.) than the referents. Statistically significant univariate correlations were observed between exposure to Hatch sol Mn in the welding aerosol and B-Mn, S-Mn and U-Mn respectively. Pearson's correlation coefficient between mean Hatch sol Mn of two days preceding the collection of biological samples and U-Mn was 0.46 (p < 0.001). The duration of employment as a welder in years was also associated with B-Mn and S-Mn, but not with U-Mn. Statistically significantly higher U-Mn and B-Mn were observed in welders currently exposed to even less than 12 and 6 μg m (-3) Hatchsol Mn, respectively. When using the 95(th) percentile concentration among the referents as a cut-point, 70.0 and 64.5% of the most highly exposed welders exceeded this level with respect to B-Mn and U-Mn. The concentrations of B-Mn, S-Mn and U-Mn were all highly correlated in the welders, but not in the referents.

Potential threat of heavy metals in re-suspended dusts on building surfaces in oilfield city

NASA Astrophysics Data System (ADS)

Kong, Shaofei; Lu, Bing; Bai, Zhipeng; Zhao, Xueyan; Chen, Li; Han, Bin; Li, Zhiyong; Ji, Yaqin; Xu, Yonghai; Liu, Yong; Jiang, Hua

2011-08-01

30 re-suspended dust samples were collected from building surfaces of an oilfield city, then re-suspended through PM 2.5, PM 10 and PM 100 inlets and analyzed for 10 metals including V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb by inductively coupled plasma-mass spectroscopy. Metals concentrations in different fractions and locations were studied. Metals sources were identified by cluster and primary component analysis. The potential risk to human health was assessed by human exposure model. Results showed that Zn, Mn, Pb and Cu were higher in all the three fractions. V, Cr, Mn and Co ranged close to the background values of Chinese soil indicating that they were mainly from crustal materials. Concentrations of Zn, Mn, Pb, V, Cr, Ni, Co and Cd were higher in old district than that in new district for the three fractions. The PM 2.5/PM 10, PM 10/PM 100 and PM 2.5/PM 100 ratios were higher for Zn, Cd, Cu, Pb, Ni, As and Cr (all higher than 1.0), and lower for Co, Mn and V (all less than or close to 1.0) which meant that anthropologic sources associated metals were more easily accumulated in finer particles than metals from crustal materials. Spatial variations indicated that the ten metals peaked at surroundings near railway station, gas stations, industrial boilers and machine manufacturing plant implying the influence of local vehicle emission, fossil fuel combustion and industrial activities as well as crustal materials which was verified by cluster analysis and primary component analysis results. Ingestion of dust particles appeared to be the main route of exposure to re-suspended dust. Hazard Indexes of As were both highest for children and adult which could be a potential threat to human health for non-cancer effect and it also exhibited the highest values for cancer effect as 1.01E-06, 7.04E-07 and 7.21E-07 for PM 2.5, PM 10 and PM 100, respectively.

Magnetic and electrical properties of several Mn-based amorphous alloys

NASA Astrophysics Data System (ADS)

Obi, Y.; Morita, H.; Fujimori, H.

1987-03-01

Magnetic and electrical properties of amorphous Mn-Y, Mn-Zr, and Mn-Nb alloys have been investigated. All these alloys have a temperature-dependent susceptibility which is well fitted by a Curie-Weiss law. This implies the existence of localized magnetic moments associated with the Mn atoms. In addition, amorphous Mn-Y alloys exhibit spin-glass characteristics at low temperature. The experimental results of the electrical resistivity show that the temperature coefficient of resistivity (TCR) of both Mn-Y and Mn-Zr are negative, while Mn-Nb has a positive TCR. On the other hand, the resistivity-temperature curves of Mn-Zr and Mn-Nb have nearly the same tendency but are different from that of Mn-Y.

Creation of a 3Mn/1Fe cluster in the oxygen-evolving complex of photosystem II and investigation of its functional activity.

PubMed

Semin, B К; Davletshina, L N; Seibert, M; Rubin, A B

2018-01-01

Extraction of Mn cations from the oxygen-evolving complex (OEC) of Ca-depleted PSII membranes (PSII[-Ca,4Mn]) by reductants like hydroquinone (H 2 Q) occurs with lower efficiency at acidic pH (2Mn/reaction center [RC] are extracted at pH5.7) than at neutral pH (3Mn/RC are extracted at pH6.5) [Semin et al. Photosynth. Res. 125 (2015) 95]. Fe(II) also extracts Mn cations from PSII(-Ca,4Mn), but only 2Mn/RC at pH6.5, forming a heteronuclear 2Mn/2Fe cluster [Semin and Seibert, J. Bioenerg. Biomembr. 48 (2016) 227]. Here we investigated the efficiency of Mn extraction by Fe(II) at acidic pH and found that Fe(II) cations can extract only 1Mn/RC from PSII(-Ca,4Mn) membranes at pH 5.7, forming a 3Mn/1Fe cluster. Also we found that the presence of Fe cations in a heteronuclear cluster (2Mn/2Fe) increases the resistance of the remaining Mn cations to H 2 Q action, since H 2 Q can extract Mn cations from homonuclear Mn clusters of PSII(-Ca,4Mn) and PSII(-Ca,2Mn) membranes but not from the heteronuclear cluster in PSII(-Ca,2Mn,2Fe) membranes. H 2 Q also cannot extract Mn from PSII membranes obtained by incubation of PSII(-Ca,4Mn) membranes with Fe(II) cations at pH5.7, which suggests the formation of a heteronuclear 3Mn/1Fe cluster in the OEC. Functional activity of PSII with a 3Mn/1Fe cluster was investigated. PSII preparations with a 3Mn/1Fe cluster in the OEC are able to photoreduce the exogenous electron acceptor 2,6-dichlorophenolindophenol, possibly due to incomplete oxidation of water molecules as is the case with PSII(-Ca,2Mn,2Fe) samples. However, in the contrast to PSII(-Ca,2Mn,2Fe) samples PSII(-Ca,3Mn,1Fe) membranes can evolve O 2 at a low rate in the presence of exogenous Ca 2+ (at about 27% of the rate of O 2 evolution in native PSII membranes). The explanation for this phenomenon (either water splitting and production of molecular O 2 by the 3Mn/1Fe cluster or apparent O 2 evolution due to minor contamination of PSII(3Mn,1Fe) samples with PSII(-Ca,4Mn) membranes) is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Manganese in plasma: a promising biomarker of exposure to Mn in welders. A pilot study.

PubMed

Hoet, Perrine; Vanmarcke, Els; Geens, Tom; Deumer, Gladys; Haufroid, Vincent; Roels, Harry A

2012-08-13

There is raising concern about the potential neurotoxic effects of manganese (Mn) inhalation exposure in welders. Because most of the airborne particles in welding fume are in the respirable fraction, their bioavailability is likely to be higher than for coarser dust exposure. No well-validated biomarker for Mn exposure is available. To investigate the interest of measuring Mn in plasma (Mn-P) and urine (Mn-U) as biomarkers of exposure in a group of 28 welders whose tasks were only welding-related. Ambient air exposure to Mn (Mn-air) was determined by personal full-shift measurements on Monday and Tuesday. On the same days, blood and urine samples were collected before and after the shift. Mn-air varied from 1.3 to 729 μg/m(3) (GM 27.7). For Mn-U 65% of the values in welders were below the LOQ (0.20 μg/L). Compared to controls, the welders' Mn-P averaged 33% higher (1.5 vs 2.0 μg/L). In welders, the after-shift Mn-P values correlated well with Mn-air above 10 μg/m(3). In spite of similar Mn-air exposure on Monday and Tuesday, the relationships between Mn-air and after-shift Mn-P strikingly differed on Tuesday in that the inflection in the relationship was less obvious and the slope of the regression line (Mn-P after-shift/logMn-air) for a doubling of logMn-air was 2.3 times lower than on Monday. On Monday (the first day of the workweek), a Mn-P value of 2 μg/L could distinguish Mn-air exposure above or below 20 μg/m(3) with a sensitivity of 69% and a specificity of 82%. This preliminary study indicates that Mn-P is a promising biomarker of current exposure to Mn in welders and lends biological plausibility to the intended change for the Mn TLV-TWA of 20 μg/m(3) proposed by ACGIH for respirable Mn particulate. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Manganese in the shell of the bivalve Mytilus edulis: Seawater Mn or physiological control?

NASA Astrophysics Data System (ADS)

Freitas, Pedro S.; Clarke, Leon J.; Kennedy, Hilary; Richardson, Christopher A.

2016-12-01

Manganese in the shell calcite of marine bivalves has been suggested to reflect ambient seawater Mn concentrations, thus providing a high-resolution archive of past seawater Mn concentrations. However, a quantitative relationship between seawater Mn and shell Mn/Ca ratios, as well as clear understanding of which process(es) control(s) shell Mn/Ca, are still lacking. Blue mussels, Mytilus edulis, were grown in a one-year duration field experiment in the Menai Strait, U.K., to study the relationship between seawater particulate and dissolved Mn2+ concentrations and shell calcite Mn/Ca ratios. Shell Mn/Ca showed a well-defined intra-annual double-peak, with maximum values during early spring and early summer and low values during autumn and winter. Seawater particulate Mn peaked during winter and autumn, with a series of smaller peaks during spring and summer, whereas dissolved Mn2+ exhibited a marked single maximum during late-spring to early-summer, being low during the remainder of the year. Consequently, neither seawater particulate Mn nor dissolved Mn2+ concentrations explain the intra-annual variation of shell Mn/Ca ratios. A physiological control on shell Mn/Ca ratios is evident from the strong similarity and timing of the double-peaked intra-annual variations of Mn/Ca and shell growth rate (SGR), the latter corresponding to periods of increased metabolic activity (as indicated by respiration rate). It is thus likely that in M. edulis SGR influences shell Mn/Ca by altering the concentration or activity of Mn2+ within the extra-pallial fluid (EPF), by changing the flux of Mn into or the proportion of protein bound Mn within the EPF. By linking shell Mn/Ca ratios to the endogenous and environmental factors that determine growth and metabolic activity, this study helps to explain the lack of a consistent relationship between shell Mn/Ca in marine bivalve shell calcite and seawater particulate and dissolved Mn2+ concentrations. The use of Mn content from M. edulis shell calcite as a proxy for the dissolved and/or particulate Mn concentrations, and thus the biogeochemical processes that control them, remains elusive.

Mn(II,III) oxidation and MnO 2 mineralization by an expressed bacterial multicopper oxidase

DOE PAGES

Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung -Woo; ...

2013-07-01

Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of themore » enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. Lastly, with the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs.« less

Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

NASA Astrophysics Data System (ADS)

Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung-Woo; Spiro, Thomas G.; Tebo, Bradley M.

2013-07-01

Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of the enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. With the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs.

Long-term manganese-toxicity-induced alterations of physiology and leaf protein profiles in two Citrus species differing in manganese-tolerance.

PubMed

You, Xiang; Yang, Lin-Tong; Qi, Yi-Ping; Guo, Peng; Lai, Ning-Wei; Ye, Xin; Li, Qiang; Chen, Li-Song

2017-11-01

Manganese (Mn)-intolerant 'Sour pummelo' (Citrus grandis) and Mn-tolerant 'Xuegan' (Citrus sinensis) seedlings were irrigated for 17 weeks with 2 (control) or 600μM (Mn-toxicity or -excess) MnSO 4 . C. sinensis had higher Mn-tolerance than C. grandis, as indicated by the higher photosynthesis rates in Mn-excess C. sinensis leaves. Under Mn-toxicity, Mn levels were similar between C. sinensis and C. grandis roots, but lower in C. sinensis leaves than in C. grandis leaves. This might be responsible for C. sinensis Mn-tolerance. Using two-dimensional electrophoresis, we identified more differentially abundant proteins (DAPs) in Mn-excess C. grandis than in Mn-excess C. sinensis leaves, which agrees with the higher Mn levels in Mn-excess C. grandis leaves. DAPs were mainly related to carbohydrate and energy metabolism, stress response, and protein and amino acid metabolism. DAPs involved in the cytoskeleton and signal transduction were found only in Mn-excess C. grandis leaves. We isolated more photosynthesis-related proteins with decreased abundances in Mn-excess C. grandis leaves than in Mn-excess C. sinensis leaves, which might account for the larger decrease in photosynthesis rates in C. grandis leaves. The abundances of proteins involved in reactive oxygen species (ROS) scavenging and photorespiration were increased in Mn-excess C. grandis leaves, while only proteins involved in ROS detoxification were increased in Mn-excess C. sinensis leaves. This agrees with the increased requirement for dissipating the excess absorbed light energy, which was higher in Mn-excess C. grandis leaves than Mn-excess C. sinensis leaves because Mn-toxicity inhibited photosynthesis to a greater degree in C. grandis leaves. Copyright © 2017 Elsevier GmbH. All rights reserved.

Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

PubMed Central

Butterfield, Cristina N.; Soldatova, Alexandra V.; Lee, Sung-Woo; Spiro, Thomas G.; Tebo, Bradley M.

2013-01-01

Reactive Mn(IV) oxide minerals are ubiquitous in the environment and control the bioavailability and distribution of many toxic and essential elements and organic compounds. Their formation is thought to be dependent on microbial enzymes, because spontaneous Mn(II) to Mn(IV) oxidation is slow. Several species of marine Bacillus spores oxidize Mn(II) on their exosporium, the outermost layer of the spore, encrusting them with Mn(IV) oxides. Molecular studies have identified the mnx (Mn oxidation) genes, including mnxG, encoding a putative multicopper oxidase (MCO), as responsible for this two-electron oxidation, a surprising finding because MCOs only catalyze single-electron transfer reactions. Characterization of the enzymatic mechanism has been hindered by the lack of purified protein. By purifying active protein from the mnxDEFG expression construct, we found that the resulting enzyme is a blue (absorption maximum 590 nm) complex containing MnxE, MnxF, and MnxG proteins. Further, by analyzing the Mn(II)- and (III)-oxidizing activity in the presence of a Mn(III) chelator, pyrophosphate, we found that the complex facilitates both electron transfers from Mn(II) to Mn(III) and from Mn(III) to Mn(IV). X-ray absorption spectroscopy of the Mn mineral product confirmed its similarity to Mn(IV) oxides generated by whole spores. Our results demonstrate that Mn oxidation from soluble Mn(II) to Mn(IV) oxides is a two-step reaction catalyzed by an MCO-containing complex. With the purification of active Mn oxidase, we will be able to uncover its mechanism, broadening our understanding of Mn mineral formation and the bioinorganic capabilities of MCOs. PMID:23818588

Hair Manganese as an Exposure Biomarker among Welders.

PubMed

Reiss, Boris; Simpson, Christopher D; Baker, Marissa G; Stover, Bert; Sheppard, Lianne; Seixas, Noah S

2016-03-01

Quantifying exposure and dose to manganese (Mn) containing airborne particles in welding fume presents many challenges. Common biological markers such as Mn in blood or Mn in urine have not proven to be practical biomarkers even in studies where positive associations were observed. However, hair Mn (MnH) as a biomarker has the advantage over blood and urine that it is less influenced by short-term variability of Mn exposure levels because of its slow growth rate. The objective of this study was to determine whether hair can be used as a biomarker for welders exposed to manganese. Hair samples (1cm) were collected from 47 welding school students and individual air Mn (MnA) exposures were measured for each subject. MnA levels for all days were estimated with a linear mixed model using welding type as a predictor. A 30-day time-weighted average MnA (MnA30d) exposure level was calculated for each hair sample. The association between MnH and MnA30d levels was then assessed. A linear relationship was observed between log-transformed MnA30d and log-transformed MnH. Doubling MnA30d exposure levels yields a 20% (95% confidence interval: 11-29%) increase in MnH. The association was similar for hair washed following two different wash procedures designed to remove external contamination. Hair shows promise as a biomarker for inhaled Mn exposure given the presence of a significant linear association between MnH and MnA30d levels. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Hair Manganese as an Exposure Biomarker among Welders

PubMed Central

Reiss, Boris; Simpson, Christopher D.; Baker, Marissa G.; Stover, Bert; Sheppard, Lianne; Seixas, Noah S.

2016-01-01

Quantifying exposure and dose to manganese (Mn) containing airborne particles in welding fume presents many challenges. Common biological markers such as Mn in blood or Mn in urine have not proven to be practical biomarkers even in studies where positive associations were observed. However, hair Mn (MnH) as a biomarker has the advantage over blood and urine that it is less influenced by short-term variability of Mn exposure levels because of its slow growth rate. The objective of this study was to determine whether hair can be used as a biomarker for welders exposed to manganese. Hair samples (1cm) were collected from 47 welding school students and individual air Mn (MnA) exposures were measured for each subject. MnA levels for all days were estimated with a linear mixed model using welding type as a predictor. A 30-day time-weighted average MnA (MnA30d) exposure level was calculated for each hair sample. The association between MnH and MnA30d levels was then assessed. A linear relationship was observed between log-transformed MnA30d and log-transformed MnH. Doubling MnA30d exposure levels yields a 20% (95% confidence interval: 11–29%) increase in MnH. The association was similar for hair washed following two different wash procedures designed to remove external contamination. Hair shows promise as a biomarker for inhaled Mn exposure given the presence of a significant linear association between MnH and MnA30d levels. PMID:26409267

Operando identification of the point of [Mn- 2]O- 4 spinel formation during gamma-MnO 2 discharge within batteries

DOE PAGES

Gallaway, Joshua W.; Hertzberg, Benjamin J.; Zhong, Zhong; ...

2016-05-07

The rechargeability of γ-MnO 2 cathodes in alkaline batteries is limited by the formation of the [Mn 2]O 4 spinels ZnMn 2O 4 (hetaerolite) and Mn 3O 4 (hausmannite). However, the time and formation mechanisms of these spinels are not well understood. Here we directly observe γ-MnO 2 discharge at a range of reaction extents distributed across a thick porous electrode. Coupled with a battery model, this reveals that spinel formation occurs at a precise and predictable point in the reaction, regardless of reaction rate. Observation is accomplished by energy dispersive X-ray diffraction (EDXRD) using photons of high energy andmore » high flux, which penetrate the cell and provide diffraction data as a function of location and time. After insertion of 0.79 protons per γ-MnO 2 the α-MnOOH phase forms rapidly. α-MnOOH is the precursor to spinel, which closely follows. ZnMn 2O 4 and Mn 3O 4 form at the same discharge depth, by the same mechanism. The results show the final discharge product, Mn 3O 4 or Mn(OH) 2, is not an intrinsic property of γ-MnO 2. While several studies have identified Mn(OH) 2 as the final γ-MnO 2 discharge product, we observe direct conversion to Mn 3O 4 with no Mn(OH) 2.« less

Fungal oxidative dissolution of the Mn(II)-bearing mineral rhodochrosite and the role of metabolites in manganese oxide formation.

PubMed

Tang, Yuanzhi; Zeiner, Carolyn A; Santelli, Cara M; Hansel, Colleen M

2013-04-01

Microbially mediated oxidation of Mn(II) to Mn(III/IV) oxides influences the cycling of metals and remineralization of carbon. Despite the prevalence of Mn(II)-bearing minerals in nature, little is known regarding the ability of microbes to oxidize mineral-hosted Mn(II). Here, we explored oxidation of the Mn(II)-bearing mineral rhodochrosite (MnCO3 ) and characteristics of ensuing Mn oxides by six Mn(II)-oxidizing Ascomycete fungi. All fungal species substantially enhanced rhodochrosite dissolution and surface modification. Mineral-hosted Mn(II) was oxidized resulting in formation of Mn(III/IV) oxides that were all similar to δ-MnO2 but varied in morphology and distribution in relation to cellular structures and the MnCO3 surface. For four fungi, Mn(II) oxidation occurred along hyphae, likely mediated by cell wall-associated proteins. For two species, Mn(II) oxidation occurred via reaction with fungal-derived superoxide produced at hyphal tips. This pathway ultimately resulted in structurally unique Mn oxide clusters formed at substantial distances from any cellular structure. Taken together, findings for these two fungi strongly point to a role for fungal-derived organic molecules in Mn(III) complexation and Mn oxide templation. Overall, this study illustrates the importance of fungi in rhodochrosite dissolution, extends the relevance of biogenic superoxide-based Mn(II) oxidation and highlights the potential role of mycogenic exudates in directing mineral precipitation. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Manganese acquisition by Lactobacillus plantarum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Archibald, F.S.; Duong, M.N.

1984-04-01

Lactobacillus plantarum has an unusually high Mn(II) requirement for growth and accumulated over 30 mM intracellular Mn(II). The acquisition of Mn(II) by L. plantarum occurred via a specific active transport system powered by the transmembrane proton gradient. The Mn(II) uptake system has a K/sub m/ of 0.2 ..mu..M and a V/sub max/ of 24 nmol mg/sup -1/ of protein min/sup -1/. Above a medium Mn(II) concentration of 200 ..mu..M, the intracellular Mn(II) level was independent of the medium Mn(II) and unresponsive to oxygen stresses but was reduced by phosphate limitation. At a pH of 5.5, citrate, isocitrate, and cis-aconitate effectivelymore » promoted MN(II) uptake, although measurable levels of 1,5-(/sup 14/C)citrate were not accumulated. When cells were presented with equimolar Mn(II) and Cd(II), Cd(II) was preferentially taken up by the Mn(II) transport system. Both Mn(II) and Cd(II) uptake were greatly increased by Mn(II) starvation. Mn(II) uptake by Mn(II)-starved cells was subject to a negative feedback regulatory mechanism functioning less than 1 min after exposure of the cells to Mn(II) and independent of protein synthesis. When presented with a relatively large amount of exogenous Mn(II), Mn(II)-starved cells exhibited a measurable efflux of their internal Mn(II), but the rate was only a small fraction of the maximal Mn(II) uptake rate.« less

Magnetic properties of transition metal substituted La 0.85Ag 0.15Mn 1-yM yO 3 compounds (M=Co, Cr and Al)

NASA Astrophysics Data System (ADS)

Srivastava, S. K.; Ravi, S.

2009-12-01

In this paper we report a systematic study of Mn-site substitution by M=Co, Cr and Al in La 0.85Ag 0.15MnO 3 series to understand the magnetic interactions between Mn and other transition metals. The long-range ferromagnetic (FM) ordering of the parent compound was significantly affected by Mn-site substitution. The measured magnetic properties of Co-doped samples have been explained on the basis of FM interactions in Mn 3+-O-Mn 4+, Co 2+-O-Mn 4+, Co 3+-O-Mn 4+ networks and simultaneous antiferromagnetic (AFM) interactions in Mn 4+-O-Mn 4+, Co 2+-O-Mn 3+ networks. The magnetic properties of Cr-doped compounds could be understood on the basis of double exchange FM interactions in Mn 3+-O 2--Mn 4+ networks and competing AFM in Cr 3+-O-Mn 4+, Mn 4+-O-Mn 4+, Cr 3+-O-Mn 3+ networks. However, it is found that the doping of Al ions play a role of magnetic dilution, without contributing any other competing magnetic interaction. The field variations of magnetization of all the above three series could be analysed by fitting to Brillouin function model and the effective spin contribution for FM has been determined. The measured saturation magnetization has been explained quantitatively.

Mn2+ concentration manipulated red emission in BaMg2Si2O7:Eu2+,Mn2+

NASA Astrophysics Data System (ADS)

Ye, Song; Zhang, Jiahua; Zhang, Xia; Lu, Shaozhe; Ren, Xinguang; Wang, Xiaojun

2007-02-01

The luminescent properties of concentration dependence are reported in BaMg2Si2O7:Eu2+,Mn2+ red phosphor. It is observed that the broad red emission of Mn2+ consists of two bands, located at 620 and 675 nm, respectively, which are attributed to two different Mn2+ centers [Mn2+(I) and Mn2+(II)] substituting for two nonidentical Mg2+ sites [Mg2+(I) and Mg2+(II)] in the host. It is also found that the relative emission intensity of the Mn2+(II) to the Mn2+(I) increases with increasing Mn2+ concentration, leading to a red-shift of the overall emission. A detail analysis on the energy transfer from Eu2+ to the two Mn2+ centers is presented, which indicates that the number ratio of Mn2+(II) to Mn2+(I) increases with increasing Mn2+ concentration. This result is interpreted by the preferential formation of Mn2+(I) substituting for Mg2+(I) site. Based on energy transfer, the emission intensity ratios of Mn2+(I) to Eu2+ and Mn2+(II) to Eu2+, which is Mn2+ concentration dependent, are calculated using related fluorescence lifetimes. The calculated results are in good agreement with that obtained experimentally in the emission spectra.

Reduced graphene oxide supported MnS nanotubes hybrid as a novel non-precious metal electrocatalyst for oxygen reduction reaction with high performance

NASA Astrophysics Data System (ADS)

Tang, Yongfu; Chen, Teng; Guo, Wenfeng; Chen, Shunji; Li, Yanshuai; Song, Jianzheng; Chang, Limin; Mu, Shichun; Zhao, Yufeng; Gao, Faming

2017-09-01

Electronic structure of Mn cations, electric conductivity of active materials and three dimensional structure for mass transport play vital roles in the electrocatalytic activity of Mn-based electrocatalysts for oxygen reduction reaction (ORR). To construct efficient and robust Mn-based electrocatalysts, MnS nanotubes anchored on reduced graphene oxide (MnS-NT@rGO) hybrid was synthesized and used as a novel non-precious metal electrocatalyst for ORR. The formation of nano-tubular structure, which offers more active sites and suitable channels for mass transport to enhance the electrocatalytic activity towards ORR, are carefully illustrated based on the core-dissolution/shell-recrystallization type Ostwald ripening effect. Tuned electronic structure of Mn cations, enhanced electric conductivity and suitable nano-tubular structure endow MnS-NT@rGO electrocatalyst comparative catalytic activity to commercial 20 wt % Pt/C in alkaline electrolyte. The MnS-NT@rGO electrocatalyst exhibits higher catalytic activity than rGO supported MnS nanoparticles (MnS-NP@rGO) and MnS nanotubes without rGO substrate (MnS-NT), as well as rGO supported Mn(OH)2 (Mn(OH)2@rGO) and rGO supported MnO (MnO@rGO). Moreover, the MnS-NT@rGO electrocatalyst shows superior durability and methanol tolerance to commercial Pt/C.

Multicopper Oxidase Involvement in Both Mn(II) and Mn(III) Oxidation during Bacterial Formation of MnO2

PubMed Central

Soldatova, Alexandra V.; Butterfield, Cristina; Oyerinde, Oyeyemi F.; Tebo, Bradley M.; Spiro, Thomas G.

2013-01-01

Global cycling of environmental manganese requires catalysis by bacteria and fungi for MnO2 formation, since abiotic Mn(II) oxidation is slow under ambient conditions. Genetic evidence from several bacteria implicates multicopper oxidases (MCOs) as being required for MnO2 formation. However, MCOs catalyze one-electron oxidations, whereas conversion of Mn(II) to MnO2 is a two-electron process. Trapping experiments with pyrophosphate (PP), a Mn(III) chelator, have demonstrated that Mn(III) is an intermediate in Mn(II) oxidation when mediated by exosporium from the Mn-oxidizing bacterium Bacillus SG-1. The reaction of Mn(II) depends on O2 and is inhibited by azide, consistent with MCO catalysis. We show that the subsequent conversion of Mn(III) to MnO2 also depends on O2 and is inhibited by azide. Thus, both oxidation steps appear to be MCO-mediated, likely by the same enzyme, indicated by genetic evidence to be the MnxG gene product. We propose a model of how the manganese oxidase active site may be organized to couple successive electron transfers to the formation of polynuclear Mn(IV) complexes as precursors to MnO2 formation. PMID:22892957

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation.

PubMed

Lassalle-Kaiser, Benedikt; Hureau, Christelle; Pantazis, Dimitrios A; Pushkar, Yulia; Guillot, Régis; Yachandra, Vittal K; Yano, Junko; Neese, Frank; Anxolabéhère-Mallart, Elodie

2010-07-01

Activation of a water molecule by the electrochemical oxidation of a Mn-aquo complex accompanied by the loss of protons is reported. The sequential (2 × 1 electron/1 proton) and direct (2 electron/2 proton) proton-coupled electrochemical oxidation of a non-porphyrinic six-coordinated Mn(II)OH 2 complex into a mononuclear Mn(O) complex is described. The intermediate Mn(III)OH 2 and Mn(III)OH complexes are electrochemically prepared and analysed. Complete deprotonation of the coordinated water molecule in the Mn(O) complex is confirmed by electrochemical data while the analysis of EXAFS data reveals a gradual shortening of an Mn-O bond upon oxidation from Mn(II)OH 2 to Mn(III)OH and Mn(O). Reactivity experiments, DFT calculations and XANES pre-edge features provide strong evidence that the bonding in Mn(O) is best characterized by a Mn(III)-oxyl description. Such oxyl species could play a crucial role in natural and artificial water splitting reactions. We provide here a synthetic example for such species, obtained by electrochemical activation of a water ligand.

Structure and properties of Mn4Cl9: an antiferromagnetic binary hyperhalogen.

PubMed

Li, Yawei; Zhang, Shunhong; Wang, Qian; Jena, Puru

2013-02-07

Calculations based on density functional theory show that the structure of Mn(4)Cl(9) anion is that of a Mn atom at the core surrounded by three MnCl(3) moieties. Since Mn is predominantly divalent and MnCl(3) is known to be a superhalogen with a vertical detachment energy (VDE) of 5.27 eV, Mn(4)Cl(9) can be viewed as a hyperhalogen with the formula unit Mn(MnCl(3))(3). Indeed, the calculated VDE of Mn(4)Cl(9) anion, namely 6.76 eV, is larger than that of MnCl(3) anion. More importantly, unlike previously discovered hyperhalogens, Mn(4)Cl(9) is the first such hyperhalogen species composed of only two constituent atoms. We further show that Mn(4)Cl(9) can be used as a ligand to design molecules with even higher VDEs. For example, Li[Mn(MnCl(3))(3)](2) anion has a VDE of 7.26 eV. These negatively charged clusters are antiferromagnetic with most of the magnetic moments localized at the Mn sites. Our studies show new pathways for creating binary hyperhalogens.

Structure and properties of Mn4Cl9: An antiferromagnetic binary hyperhalogen

NASA Astrophysics Data System (ADS)

Li, Yawei; Zhang, Shunhong; Wang, Qian; Jena, Puru

2013-02-01

Calculations based on density functional theory show that the structure of Mn4Cl9 anion is that of a Mn atom at the core surrounded by three MnCl3 moieties. Since Mn is predominantly divalent and MnCl3 is known to be a superhalogen with a vertical detachment energy (VDE) of 5.27 eV, Mn4Cl9 can be viewed as a hyperhalogen with the formula unit Mn(MnCl3)3. Indeed, the calculated VDE of Mn4Cl9 anion, namely 6.76 eV, is larger than that of MnCl3 anion. More importantly, unlike previously discovered hyperhalogens, Mn4Cl9 is the first such hyperhalogen species composed of only two constituent atoms. We further show that Mn4Cl9 can be used as a ligand to design molecules with even higher VDEs. For example, Li[Mn(MnCl3)3]2 anion has a VDE of 7.26 eV. These negatively charged clusters are antiferromagnetic with most of the magnetic moments localized at the Mn sites. Our studies show new pathways for creating binary hyperhalogens.

Direct effects of manganese compounds on dopamine and its metabolite Dopac: an in vitro study

PubMed Central

Sistrunk, Shannon C.; Ross, Matthew K.; Filipov, Nikolay M.

2007-01-01

Following combustion of fuel containing the additive methylcyclopentadienyl-manganese-tricarbonyl (MMT), manganese phosphate (MnPO4) and manganese sulfate (MnSO4) are emitted in the atmosphere. Manganese chloride (MnCl2), another Mn2+ species, is widely used experimentally. Using rat striatal slices, we found that MnPO4 decreased tissue and media dopamine (DA) and media Dopac (a DA metabolite) levels substantially more than either MnCl2 or MnSO4; antioxidants were partially protective. Also, both MnCl2 and MnPO4 (more potently) oxidized DA and Dopac even in the absence of tissue in the media, suggesting a direct interaction between Mn and DA/Dopac. Because aminochrome is a major oxidation product of DA, we next determined whether MnPO4 will be more potent in forming aminochrome than MnCl2 or MnSO4 which, indeed, was the case. Thus, a potential additional mechanism for the neurotoxic effects of environmentally-relevant forms of Mn, MnPO4 in particular, is the generation of reactive DA intermediates. PMID:18449324

Distinct effects of Al3+ doping on the structure and properties of hexagonal turbostratic birnessite: A comparison with Fe3+ doping

NASA Astrophysics Data System (ADS)

Yin, Hui; Kwon, Kideok D.; Lee, Jin-Yong; Shen, Yi; Zhao, Huaiyan; Wang, Xiaoming; Liu, Fan; Zhang, Jing; Feng, Xionghan

2017-07-01

Hexagonal turbostratic birnessite, one of the most reactive Mn oxide minerals, is ubiquitous throughout the ocean floor to the surface environment. During its crystallization, birnessite may coexist with Al3+, which is the third most abundant crustal element. However, interactions of Al3+ with birnessite compared to the transition metal (TM) ions have rarely been explored thus far. This study examines the structure and properties of Al3+-doped hexagonal turbostratic birnessite to obtain insights into the interaction of metal cations with birnessite-like minerals in natural environments. For Al3+-incorporated birnessite, the crystal chemistry of Al3+, as well as alteration in the mineral structure, physicochemical properties, and reactivity toward the sorption of Pb2+/Zn2+ is investigated by powder X-ray diffraction, chemical analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Electronic structure calculations based on density functional theory (DFT) are further combined to aid in the experimental interpretation of Al3+ incorporation. As a comparative system, Fe3+-coprecipitated birnessite is also examined. Under the experimental conditions used, only a small amount of Al3+ is incorporated into birnessite, with a final Al/(Al + Mn) molar ratio of ∼0.07, whereas Fe3+ is incorporated into birnessite with a final Fe/(Fe + Mn) molar ratio of up to ∼0.21. Irrespective of metal type, the incorporation of a metal cation significantly alters the physicochemical properties of birnessite, such as decrease in the thickness of crystals along the c∗ axis and coherent scattering domain sizes in the a-b plane and the Mn average oxidation state, increase in the specific surface area and the total amount of hydroxyl groups, in which the contents of hydroxyl groups around vacancies are decreased. The lattice parameters in the a-b plane tend to decrease in Al-incorporated birnessites but first significantly decrease and then increase in Fe-incorporated birnessites. In Fe-incorporated birnessites, ∼32-50% of the total Fe3+ is located inside the Mn octahedral sheets (INC species). In Al-incorporated birnessites, the edge- and corner-sharing Mn-Mn distances gradually decrease. Density function theory (DFT) computation results support that the dominant species in Al-birnessite is a triple-corner-sharing complex on vacancies. The DFT geometry optimization further demonstrates that the in-plane cell size experimentally observed for these birnessites depends on not only the metal type but also its position in the mineral. The Al- or Fe-birnessites exhibit significantly increased adsorption capacities for Pb2+ but reduced capacities for Zn2+. The metal incorporation effects on the chemical reactivity are discussed with the observed changes in the particle size and available vacancy sites.

Ultrathin ZnSe nanowires: one-pot synthesis via a heat-triggered precursor slow releasing route, controllable Mn doping and application in UV and near-visible light detection.

PubMed

Li, Dong; Xing, Guanjie; Tang, Shilin; Li, Xiaohong; Fan, Louzhen; Li, Yunchao

2017-10-12

We report herein a heat-triggered precursor slow releasing route for the one-pot synthesis of ultrathin ZnSe nanowires (NWs), which relies on the gradual dissolving of Se powder into oleylamine containing a soluble Zn precursor under heating. This route allows the reaction system to maintain a high monomer concentration throughout the entire reaction process, thus enabling the generation of ZnSe NWs with diameter down to 2.1 nm and length approaching 400 nm. The size-dependent optical properties and band-edge energy levels of the ZnSe NWs were then explored in depth by UV-visible spectroscopy and cyclic voltammetry, respectively. Considering their unique absorption properties, these NWs were specially utilized for fabricating photoelectrochemical-type photodetectors (PDs). Impressively, the PDs based on the ZnSe NWs with diameters of 2.1 and 4.5 nm exhibited excellent responses to UVA and near-visible light, respectively: both possessed ultrahigh on/off ratios (5150 for UVA and 4213 for near-visible light) and ultrawide linear response ranges (from 2.0 to 9000 μW cm -2 for UVA and 5.0 to 8000 μW cm -2 for near-visible light). Furthermore, these ZnSe NWs were selectively doped with various amounts of Mn 2+ to tune their emission properties. As a result, ZnSe NW film-based photochromic cards were creatively developed for visually detecting UVA and near-visible radiation.

Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Binuclear Activation Mechanism.

PubMed

Soldatova, Alexandra V; Tao, Lizhi; Romano, Christine A; Stich, Troy A; Casey, William H; Britt, R David; Tebo, Bradley M; Spiro, Thomas G

2017-08-23

The bacterial protein complex Mnx contains a multicopper oxidase (MCO) MnxG that, unusually, catalyzes the two-electron oxidation of Mn(II) to MnO 2 biomineral, via a Mn(III) intermediate. Although Mn(III)/Mn(II) and Mn(IV)/Mn(III) reduction potentials are expected to be high, we find a low reduction potential, 0.38 V (vs Normal Hydrogen Electrode, pH 7.8), for the MnxG type 1 Cu 2+ , the electron acceptor. Indeed the type 1 Cu 2+ is not reduced by Mn(II) in the absence of molecular oxygen, indicating that substrate oxidation requires an activation step. We have investigated the enzyme mechanism via electronic absorption spectroscopy, using chemometric analysis to separate enzyme-catalyzed MnO 2 formation from MnO 2 nanoparticle aging. The nanoparticle aging time course is characteristic of nucleation and particle growth; rates for these processes followed expected dependencies on Mn(II) concentration and temperature, but exhibited different pH optima. The enzymatic time course is sigmoidal, signaling an activation step, prior to turnover. The Mn(II) concentration and pH dependence of a preceding lag phase indicates weak Mn(II) binding. The activation step is enabled by a pK a > 8.6 deprotonation, which is assigned to Mn(II)-bound H 2 O; it induces a conformation change (consistent with a high activation energy, 106 kJ/mol) that increases Mn(II) affinity. Mnx activation is proposed to decrease the Mn(III/II) reduction potential below that of type 1 Cu(II/I) by formation of a hydroxide-bridged binuclear complex, Mn(II)(μ-OH)Mn(II), at the substrate site. Turnover is found to depend cooperatively on two Mn(II) and is enabled by a pK a 7.6 double deprotonation. It is proposed that turnover produces a Mn(III)(μ-OH) 2 Mn(III) intermediate that proceeds to the enzyme product, likely Mn(IV)(μ-O) 2 Mn(IV) or an oligomer, which subsequently nucleates MnO 2 nanoparticles. We conclude that Mnx exploits manganese polynuclear chemistry in order to facilitate an otherwise difficult oxidation reaction, as well as biomineralization. The mechanism of the Mn(III/IV) conversion step is elucidated in an accompanying paper .

Oxidative Formation and Removal of Complexed Mn(III) by Pseudomonas Species

PubMed Central

Wright, Mitchell H.; Geszvain, Kati; Oldham, Véronique E.; Luther, George W.; Tebo, Bradley M.

2018-01-01

The observation of significant concentrations of soluble Mn(III) complexes in oxic, suboxic, and some anoxic waters has triggered a re-evaluation of the previous Mn paradigm which focused on the cycling between soluble Mn(II) and insoluble Mn(III,IV) species as operationally defined by filtration. Though Mn(II) oxidation in aquatic environments is primarily bacterially-mediated, little is known about the effect of Mn(III)-binding ligands on Mn(II) oxidation nor on the formation and removal of Mn(III). Pseudomonas putida GB-1 is one of the most extensively investigated of all Mn(II) oxidizing bacteria, encoding genes for three Mn oxidases (McoA, MnxG, and MopA). P. putida GB-1 and associated Mn oxidase mutants were tested alongside environmental isolates Pseudomonas hunanensis GSL-007 and Pseudomonas sp. GSL-010 for their ability to both directly oxidize weakly and strongly bound Mn(III), and to form these complexes through the oxidation of Mn(II). Using Mn(III)-citrate (weak complex) and Mn(III)-DFOB (strong complex), it was observed that P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 and mutants expressing only MnxG and McoA were able to directly oxidize both species at varying levels; however, no oxidation was detected in cultures of a P. putida mutant expressing only MopA. During cultivation in the presence of Mn(II) and citrate or DFOB, P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 formed Mn(III) complexes transiently as an intermediate before forming Mn(III/IV) oxides with the overall rates and extents of Mn(III,IV) oxide formation being greater for Mn(III)-citrate than for Mn(III)-DFOB. These data highlight the role of bacteria in the oxidative portion of the Mn cycle and suggest that the oxidation of strong Mn(III) complexes can occur through enzymatic mechanisms involving multicopper oxidases. The results support the observations from field studies and further emphasize the complexity of the geochemical cycling of manganese. PMID:29706936

Oxidative Formation and Removal of Complexed Mn(III) by Pseudomonas Species.

PubMed

Wright, Mitchell H; Geszvain, Kati; Oldham, Véronique E; Luther, George W; Tebo, Bradley M

2018-01-01

The observation of significant concentrations of soluble Mn(III) complexes in oxic, suboxic, and some anoxic waters has triggered a re-evaluation of the previous Mn paradigm which focused on the cycling between soluble Mn(II) and insoluble Mn(III,IV) species as operationally defined by filtration. Though Mn(II) oxidation in aquatic environments is primarily bacterially-mediated, little is known about the effect of Mn(III)-binding ligands on Mn(II) oxidation nor on the formation and removal of Mn(III). Pseudomonas putida GB-1 is one of the most extensively investigated of all Mn(II) oxidizing bacteria, encoding genes for three Mn oxidases (McoA, MnxG, and MopA). P. putida GB-1 and associated Mn oxidase mutants were tested alongside environmental isolates Pseudomonas hunanensis GSL-007 and Pseudomonas sp. GSL-010 for their ability to both directly oxidize weakly and strongly bound Mn(III), and to form these complexes through the oxidation of Mn(II). Using Mn(III)-citrate (weak complex) and Mn(III)-DFOB (strong complex), it was observed that P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 and mutants expressing only MnxG and McoA were able to directly oxidize both species at varying levels; however, no oxidation was detected in cultures of a P. putida mutant expressing only MopA. During cultivation in the presence of Mn(II) and citrate or DFOB, P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 formed Mn(III) complexes transiently as an intermediate before forming Mn(III/IV) oxides with the overall rates and extents of Mn(III,IV) oxide formation being greater for Mn(III)-citrate than for Mn(III)-DFOB. These data highlight the role of bacteria in the oxidative portion of the Mn cycle and suggest that the oxidation of strong Mn(III) complexes can occur through enzymatic mechanisms involving multicopper oxidases. The results support the observations from field studies and further emphasize the complexity of the geochemical cycling of manganese.

Manganese and Mn/Ca ratios in soil and vegetation in forests across the northeastern US: Insights on spatial Mn enrichment.

PubMed

Richardson, J B

2017-03-01

Manganese (Mn) cycling in the Critical Zone is important because of its role as an essential nutrient and potential toxicity to plants and organisms. Quantifying Mn enrichment in terrestrial environments has been limited since Mn is monoisotopic. However, elemental ratios of Mn/Ca ratios may be used to determine spatial Mn enrichment and in aboveground and belowground pools. The objectives of this study were to quantify the spatial variation in Mn concentrations and Mn/Ca ratios in foliage, bolewood, forest floor, and mineral soil horizons across the northeastern United States and compare Mn/Ca ratios to estimate enrichment. Forest floor and mineral soil samples were collected from 26 study sites across the northeastern United States and analyzed by strong acid digestion. Foliage and bolewood was collected from 12 of the 26 sites and analyzed for total Mn and Ca. Our results show forest floor and mineral soil horizon Mn concentrations and Mn/Ca ratios were higher at Pennsylvania and New York sites than New Hampshire and Vermont sites. Using a modified isotope equation, enrichment factors (EF) for Mn/Ca ratios were calculated to be ~3.6 in the forest floor, upper and lower mineral soil horizons at sites in New York and Pennsylvania compared to reference sites in New Hampshire and Vermont. Foliar and bolewood Mn concentrations also decreased from Pennsylvania towards New Hampshire. Moreover, foliar and bolewood Mn concentrations were strongly correlated to forest floor, upper, and lower mineral soil Mn concentrations. It was hypothesized that internal cycling (uptake, throughfall, and litterfall) of Mn controls retention of enriched Mn in forests. Geologic influences from a lithologic gradient and soil pH gradient could also influence Mn enrichment in addition to Mn pollution. Ratios of Mn/Ca and other elemental ratios hold promise as geochemical tracers but require further development. Copyright © 2016 Elsevier B.V. All rights reserved.

Constraints on superoxide mediated formation of manganese oxides

PubMed Central

Learman, Deric R.; Voelker, Bettina M.; Madden, Andrew S.; Hansel, Colleen M.

2013-01-01

Manganese (Mn) oxides are among the most reactive sorbents and oxidants within the environment, where they play a central role in the cycling of nutrients, metals, and carbon. Recent discoveries have identified superoxide (O2−) both of biogenic and abiogenic origin as an effective oxidant of Mn(II) leading to the formation of Mn oxides. Here we examined the conditions under which abiotically produced superoxide led to oxidative precipitation of Mn and the solid-phases produced. Oxidized Mn, as both aqueous Mn(III) and Mn(III/IV) oxides, was only observed in the presence of active catalase, indicating that hydrogen peroxide (H2O2), a product of the reaction of O2− with Mn(II), inhibits the oxidation process presumably through the reduction of Mn(III). Citrate and pyrophosphate increased the yield of oxidized Mn but decreased the amount of Mn oxide produced via formation of Mn(III)-ligand complexes. While complexing ligands played a role in stabilizing Mn(III), they did not eliminate the inhibition of net Mn(III) formation by H2O2. The Mn oxides precipitated were highly disordered colloidal hexagonal birnessite, similar to those produced by biotically generated superoxide. Yet, in contrast to the large particulate Mn oxides formed by biogenic superoxide, abiotic Mn oxides did not ripen to larger, more crystalline phases. This suggests that the deposition of crystalline Mn oxides within the environment requires a biological, or at least organic, influence. This work provides the first direct evidence that, under conditions relevant to natural waters, oxidation of Mn(II) by superoxide can occur and lead to formation of Mn oxides. For organisms that oxidize Mn(II) by producing superoxide, these findings may also point to other microbially mediated processes, in particular enzymatic hydrogen peroxide degradation and/or production of organic ligand metabolites, that allow for Mn oxide formation. PMID:24027565

Stability of βMnOOH and manganese oxide deposition from springwater

USGS Publications Warehouse

Hem, J.D.; Roberson, C.E.; Fournier, Reba B.

1982-01-01

Beta MnOOH is precipitated preferentially (with respect to Mn3O4) at temperatures near O°C when Mn2+ is oxidized in aerated aqueous solutions. Upon aging in solutions open to the atmosphere a slurry of βMnOOH tends to disproportionate to form MnO2 and Mn2+. In such aged solutions, Mn2+ and H+ activities can be constant, and both the oxidation reaction Mn2++¼O2(aq) + 3/2H2O → βMnOOH (c) + 2H+ and the disproportionate reaction 2βMnOOH (c) + 2H+ → MnO2(c) + Mn2+ + 2H2O can have positive reaction affinities. It is not possible for both reactions to be in thermodynamic equilibrium in the same system unless oxygen is almost completely absent. A value for ΔGf0 of −129.8±0.6 kcal/mol was obtained for βMnOOH from experimental data by assuming that the reaction affinity for the oxidation reaction is equal to that for the disproportionation. A value for ΔGf0 for βMnOOH of −129.8±0.5 kcal/mol was determined by measuring the redox potentials for the postulated half-reaction MnO2 (c) + H+ + e− → βMnOOH (c) at 0°, 5°, and 15°C and extrapolating to 25°C. Both these values are consistent with laboratory observations that βMnOOH is less stable than γMnOOH or Mn3O4 at 25°C. Analytical data for manganese-depositing springwater samples are consistent with a nonequilibrium model involving disproportionation of either βMnOOH or Mn3O4.

Novel Co- or Ni-Mn binary oxide catalysts with hydroxyl groups for NH3-SCR of NOx at low temperature

NASA Astrophysics Data System (ADS)

Gao, Fengyu; Tang, Xiaolong; Yi, Honghong; Zhao, Shunzheng; Wang, Jiangen; Shi, Yiran; Meng, Xiaomi

2018-06-01

Novel hydroxyl-containing Me-Mn binary oxides (Me = Co, Ni) were prepared for the selective catalytic reduction of NOx with NH3 by a combined complexation-esterification method. The binary oxides of Co-MnOx and Ni-MnOx with mixed crystal phases of Mn3O4 and Co3O4, Mn2O3 and NiMnO3 were obtained at 550 °C. SCR activity decreased in the order of Mn3O4-Co3O4-OH > Mn2O3-NiMnO3-OH > Mn2O3-OH > Mn3O4-OH, benefiting from the high concentration of chemisorbed oxygen and effective electron transformation of cations. Mn2O3-containing catalysts had better selectivity to N2 than those containing Mn3O4. Higher selectivity to N2O over Mn3O4-containing catalysts was attributed to the depth dehydrogenation of coordinated NH3 by the active oxygen species with lower Mnsbnd O band energy. The typical Eley-Rideal mechanism over Mn3O4-OH and Mn3O4-Co3O4-OH, and the additional formation pathway of NH4NO3 species over Mn2O3-OH and Mn2O3-NiMnO3-OH catalysts were proposed via the in-situ DRIFTS experiments. Although the Co and Ni elements had a good role in delaying the poisoning of SO2, these catalysts were eventually sulfated by SO2 over the postponement, which might due to the metal sulfate and ammonia hydrogensulfite species.

Dissociation kinetics of Mn2+ complexes of NOTA and DOTA.

PubMed

Drahoš, Bohuslav; Kubíček, Vojtěch; Bonnet, Célia S; Hermann, Petr; Lukeš, Ivan; Tóth, Éva

2011-03-07

The kinetics of transmetallation of [Mn(nota)](-) and [Mn(dota)](2-) was investigated in the presence of Zn(2+) (5-50-fold excess) at variable pH (3.5-5.6) by (1)H relaxometry. The dissociation is much faster for [Mn(nota)](-) than for [Mn(dota)](2-) under both experimental and physiologically relevant conditions (t(½) = 74 h and 1037 h for [Mn(nota)](-) and [Mn(dota)](2-), respectively, at pH 7.4, c(Zn(2+)) = 10(-5) M, 25 °C). The dissociation of the complexes proceeds mainly via spontaneous ([Mn(nota)](-)k(0) = (2.6 ± 0.5) × 10(-6) s(-1); [Mn(dota)](2-)k(0) = (1.8 ± 0.6) × 10(-7) s(-1)) and proton-assisted pathways ([Mn(nota)](-)k(1) = (7.8 ± 0.1) × 10(-1) M(-1) s(-1); [Mn(dota)](2-)k(1) = (4.0 ± 0.6) × 10(-2) M(-1) s(-1), k(2) = (1.6 ± 0.1) × 10(3) M(-2) s(-1)). The observed suppression of the reaction rates with increasing Zn(2+) concentration is explained by the formation of a dinuclear Mn(2+)-L-Zn(2+) complex which is about 20-times more stable for [Mn(dota)](2-) than for [Mn(nota)](-) (K(MnLZn) = 68 and 3.6, respectively), and which dissociates very slowly (k(3)∼10(-5) M(-1) s(-1)). These data provide the first experimental proof that not all Mn(2+) complexes are kinetically labile. The absence of coordinated water makes both [Mn(nota)](-) and [Mn(dota)](2-) complexes inefficient for MRI applications. Nevertheless, the higher kinetic inertness of [Mn(dota)](2-) indicates a promising direction in designing ligands for Mn(2+) complexation.

Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, and density functional theory calculations.

PubMed

Hänninen, Mikko M; Välivaara, Juha; Mota, Antonio J; Colacio, Enrique; Lloret, Francesc; Sillanpää, Reijo

2013-02-18

A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromagnetic interactions since these geometrical conditions seem to favor the orthogonal arrangement of the magnetic orbitals.

Surface Mn(II) oxidation actuated by a multicopper oxidase in a soil bacterium leads to the formation of manganese oxide minerals

PubMed Central

Zhang, Zhen; Zhang, Zhongming; Chen, Hong; Liu, Jin; Liu, Chang; Ni, Hong; Zhao, Changsong; Ali, Muhammad; Liu, Fan; Li, Lin

2015-01-01

In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV). PMID:26039669

Surface Mn(II) oxidation actuated by a multicopper oxidase in a soil bacterium leads to the formation of manganese oxide minerals.

PubMed

Zhang, Zhen; Zhang, Zhongming; Chen, Hong; Liu, Jin; Liu, Chang; Ni, Hong; Zhao, Changsong; Ali, Muhammad; Liu, Fan; Li, Lin

2015-06-03

In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV).

Dissolved Mn(III) in water treatment works: Prevalence and significance.

PubMed

Johnson, Karen L; McCann, Clare M; Wilkinson, John-Luke; Jones, Matt; Tebo, Bradley M; West, Martin; Elgy, Christine; Clarke, Catherine E; Gowdy, Claire; Hudson-Edwards, Karen A

2018-09-01

Dissolved Mn(III) has been identified at all stages throughout a Water Treatment Works (WTW) receiving inflow from a peaty upland catchment in NE England. Ninety percent of the influent total manganese into the WTW is particulate Mn, in the form of Mn oxide (>0.2 μm). Approximately 9% (mean value, n = 22, range of 0-100%) of the dissolved (<0.2 μm) influent Mn is present as dissolved Mn(III). Mn(III) concentrations are highest (mean of 49% of total dissolved Mn; n = 26, range of 17-89%) within the WTW where water comes into contact with the organic-rich sludges which are produced as waste products in the WTW. These Mn(III)-containing wastewaters are recirculated to the head of the works and constitute a large input of Mn(III) into the WTW. This is the first report of Mn(III) being identified in a WTW. The ability of Mn(III) to act as both an oxidant and a reductant is of interest to the water industry. Understanding the formation and removal of Mn(III) within may help reduce Mn oxide deposits in pipe networks. Further understanding how the ratio of Mn(III) to Mn(II) can be used to optimise dissolved Mn removal would save the water industry significant money in reducing discoloration 'events' at the customers' tap. Copyright © 2018. Published by Elsevier Ltd.

Magnetism in Mn-nanowires and -clusters as δ-doped layers in group IV semiconductors (Si, Ge)

NASA Astrophysics Data System (ADS)

Simov, K. R.; Glans, P.-A.; Jenkins, C. A.; Liberati, M.; Reinke, P.

2018-01-01

Mn doping of group-IV semiconductors (Si/Ge) is achieved by embedding nanostructured Mn-layers in group-IV matrix. The Mn-nanostructures are monoatomic Mn-wires or Mn-clusters and capped with an amorphous Si or Ge layer. The precise fabrication of δ-doped Mn-layers is combined with element-specific detection of the magnetic signature with x-ray magnetic circular dichroism. The largest moment (2.5 μB/Mn) is measured for Mn-wires with ionic bonding character and a-Ge overlayer cap; a-Si capping reduces the moment due to variations of bonding in agreement with theoretical predictions. The moments in δ-doped layers dominated by clusters is quenched with an antiferromagnetic component from Mn-Mn bonding.

Mechanisms of Mn(II) catalytic oxidation on ferrihydrite surfaces and the formation of manganese (oxyhydr)oxides

NASA Astrophysics Data System (ADS)

Lan, Shuai; Wang, Xiaoming; Xiang, Quanjun; Yin, Hui; Tan, Wenfeng; Qiu, Guohong; Liu, Fan; Zhang, Jing; Feng, Xionghan

2017-08-01

Oxidation of Mn(II) is an important process that controls the mobility and bioavailability of Mn, as well as the formation of Mn (oxyhydr)oxides in natural systems. It was found that the surfaces of minerals, such as iron (oxyhydr)oxides, can accelerate Mn(II) oxidation to a certain degree, but the underlying mechanism has not been clearly understood. This study explores the reaction pathways and mechanisms of Mn(II) oxidation on ferrihydrite surfaces at neutral pH, commonly found in natural environments, by comparisons with montmorillonite, amorphous Al(OH)3, goethite, and magnetite using macroscopic experiments and spectroscopic analyses. Results show that when Mn(II) concentrations are below 4 mM, macroscopic Mn(II) adsorption on the three iron (oxyhydr)oxide surfaces conforms well to the Langmuir equation, with ferrihydrite showing the highest adsorption capacity. With Mn(II) concentrations ranging within 6-24 mM, the adsorbed Mn(II) is mainly oxidized into manganite (γ-MnOOH) and/or feitknechtite (β-MnOOH) by dissolved O2, and Mn(II) removal on a unit mass basis in the presence of magnetite is the highest compared with ferrihydrite and goethite. Ferrihydrite, a semiconductor material, shows stronger catalytic ability for Mn(II) oxidation on the same surface area than insulator minerals (i.e., montmorillonite and amorphous Al(OH)3). Additionally, the products of Mn(II) oxidation in the presence of semiconductor iron (oxyhydr)oxides (i.e., ferrihydrite, goethite, or magnetite) at the same Fe/Mn molar ratio include both manganite and a small amount of Mn(IV) minerals, and the Mn average oxidation states (Mn AOSs) of these products follow the order: magnetite > goethite > ferrihydrite. Magnetite and goethite, with relatively smaller SSAs and lower band gap energies, exhibit greater catalysis for Mn(II) oxidation than ferrihydrite at the same Fe/Mn ratio, which goes against the conventional interfacial effect and is related to the electrochemical properties. Thus, the Mn(II) catalytic oxidation by O2 on ferrihydrite surfaces should include an electrochemical pathway, i.e., electron transfer (ET) in the Mn(II)-Conduction Band (CB)Ferrihydrite-O2 complexes, in addition to the conventional two interfacial catalytic pathways, i.e., ET in the Mn(II)-Fe(II, III)-O2 complexes and direct ET in the Mn(II)-O2 complexes. These results reveal new implications for understanding the processes and mechanisms of Mn(II) oxidation on iron (oxyhydr)oxide surfaces and the abiotic formation of Mn (oxyhydr)oxides in surface environments.

Tunable multiple emissions in manganese-concentrated sulfide through simultaneous tailoring of Mn-site coordination and Mn-Mn pair geometry

NASA Astrophysics Data System (ADS)

Chen, Zitao; Song, Enhai; Ye, Shi; Zhang, Qinyuan

2017-12-01

In contrast to generally single-band visible emission feature from Mn2+, simultaneous visible (VIS) and near-infrared (NIR) multiple emissions are demonstrated in Mn2+ concentrated sulfide (MnS) by only involving a single crystallographic site. Upon varying the Mn2+-site coordination and/or Mn-Mn pairs geometry in different structural MnS, the multiple emissions from divalent manganese can be easily tuned from 575 to 720 nm (VIS) or from 880 to 900 or 1380 nm (NIR), respectively. The excitation spectroscopy and the luminescent decay, together with crystal structural analyses, are employed to investigate the electronic transition and the excited state dynamics of these Mn2+ concentrated systems. It is found that the VIS and NIR emissions can be ascribed to the isolated Mn2+ ion and exchange coupled Mn-Mn pair center, respectively. The effect of crystal field and bridging geometry, as well as temperature on the exchange coupled Mn2+ pairs NIR emissive center, is also investigated in detail. This work not only provides keen insights into the de-excitation pathway of Mn2+-concentrated material, but also offers the possibilities of designing a novel NIR emitting source for various photonic applications.

Enhanced Cycleability of Amorphous MnO₂ by Covering on α-MnO₂ Needles in an Electrochemical Capacitor.

PubMed

Liu, Quanbing; Ji, Shan; Yang, Juan; Wang, Hui; Pollet, Bruno G; Wang, Rongfang

2017-08-24

An allomorph MnO₂@MnO₂ core-shell nanostructure was developed via a two-step aqueous reaction method. The data analysis of Scanning Electron Microscopy, Transmission Electron Microscopy, X-Ray Diffraction and N₂ adsorption-desorption isotherms experiments indicated that this unique architecture consisted of a porous layer of amorphous-MnO₂ nano-sheets which were well grown onto the surface of α-MnO₂ nano-needles. Cyclic voltammetry experiments revealed that the double-layer charging and Faradaic pseudo -capacity of the MnO₂@MnO₂ capacitor electrode contributed to a specific capacitance of 150.3 F·g -1 at a current density of 0.1 A·g -1 . Long cycle life experiments on the as-prepared MnO₂@MnO₂ sample showed nearly a 99.3% retention after 5000 cycles at a current density of 2 A·g -1 . This retention value was found to be significantly higher than those reported for amorphous MnO₂-based capacitor electrodes. It was also found that the remarkable cycleability of the MnO₂@MnO₂ was due to the supporting role of α-MnO₂ nano-needle core and the outer amorphous MnO₂ layer.

Oxidation of MnO(100) and NaMnO2 formation: Characterization of Mn2+ and Mn3+ surfaces via XPS and water TPD

NASA Astrophysics Data System (ADS)

Feng, Xu; Cox, David F.

2018-09-01

The oxidation of clean and Na precovered MnO(100) has been investigated by X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and temperature programmed desorption (TPD) of adsorbed water. XPS results indicate that Mn3O4-like and Mn2O3-like surfaces can be formed by various oxidation treatments of clean and nearly-stoichiometric MnO(100), while a NaMnO2-like surface can be produced by the oxidation of MnO(100) pre-covered with multilayers of metallic Na. Water TPD results indicate that water adsorption/desorption is sensitive to the available oxidation states of surface Mn cations, and can be used to distinguish between surfaces exposing Mn2+and Mn3+ cations, or a combination of these oxidation states. Carbon dioxide and water TPD results from the NaMnO2-like surface indicate that pre-adsorbed water blocks the uptake of CO2, while water displaces pre-adsorbed CO2. No indication of a strong reactive interaction is observed between CO2, water and the NaMnO2-like surface under the conditions of our study.

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation†

PubMed Central

Lassalle-Kaiser, Benedikt; Hureau, Christelle; Pantazis, Dimitrios A.; Pushkar, Yulia; Guillot, Régis; Yachandra, Vittal K.; Yano, Junko; Neese, Frank; Anxolabéhère-Mallart, Elodie

2014-01-01

Activation of a water molecule by the electrochemical oxidation of a Mn-aquo complex accompanied by the loss of protons is reported. The sequential (2 × 1 electron/1 proton) and direct (2 electron/2 proton) proton-coupled electrochemical oxidation of a non-porphyrinic six-coordinated Mn(II)OH2 complex into a mononuclear Mn(O) complex is described. The intermediate Mn(III)OH2 and Mn(III)OH complexes are electrochemically prepared and analysed. Complete deprotonation of the coordinated water molecule in the Mn(O) complex is confirmed by electrochemical data while the analysis of EXAFS data reveals a gradual shortening of an Mn–O bond upon oxidation from Mn(II)OH2 to Mn(III)OH and Mn(O). Reactivity experiments, DFT calculations and XANES pre-edge features provide strong evidence that the bonding in Mn(O) is best characterized by a Mn(III)-oxyl description. Such oxyl species could play a crucial role in natural and artificial water splitting reactions. We provide here a synthetic example for such species, obtained by electrochemical activation of a water ligand. PMID:24772190

Effect of (Mn,Cr) co-doping on structural, electronic and magnetic properties of zinc oxide by first-principles studies

NASA Astrophysics Data System (ADS)

Aimouch, D. E.; Meskine, S.; Boukortt, A.; Zaoui, A.

2018-04-01

In this study, structural, electronic and magnetic properties of Mn doped (ZnO:Mn) and (Mn,Cr) co-doped zinc oxide (ZnO:(Mn,Cr)) have been calculated with the FP-LAPW method by using the LSDA and LSDA+U approximations. Going through three configurations of Mn,Cr co-doped ZnO corresponding to three different distances between manganese and chromium, we have analyzed that ZnO:(Mn,Cr) system is more stable in its preferred configuration2. The lattice constant of undoped ZnO that has been calculated in this study is in a good agreement with the experimental and theoretical values. It was found to be increased by doping with Mn or (Mn,Cr) impurities. The band structure calculations showed the metallic character of Mn doped and Mn,Cr co-doped ZnO. As results, by using LSDA+U (U = 6eV), we show the half-metallic character of ZnO:Mn and ZnO:Mn,Cr. We present the calculated exchange couplings d-d of Mn doped ZnO which is in a good agreement with the former FPLO calculation data and the magnetization step measurement of the experimental work. The magnetic coupling between neighboring Mn impurities in ZnO is found to be antiferromagnetic. In the case of (Mn,Cr) co-doped ZnO, the magnetic coupling between Mn and Cr impurities is found to be antiferromagnetic for configuration1 and 3, and ferromagnetic for configuration2. Thus, the ferromagnetic coupling is weak in ZnO:Mn. Chromium co-doping greatly enhance the ferromagnetism, especially when using configuration2. At last, we present the 2D and 3D spin-density distribution of ZnO:Mn and ZnO:(Mn,Cr) where the ferromagnetic state in ZnO:(Mn,Cr) comes from the strong p-d and d-d interactions between 2p-O, 3d-Mn and 3d-Cr electrons. The results of our calculations suggest that the co-doping ZnO(Mn, Cr) can be among DMS behavior for spintronic applications.

Creation of a 3Mn/1Fe cluster in the oxygen-evolving complex of photosystem II and investigation of its functional activity

DOE PAGES

Semin, B. K.; Davletshina, L. N.; Seibert, M.; ...

2017-11-11

Extraction of Mn cations from the oxygen-evolving complex (OEC) of Ca-depleted PSII membranes (PSII[-Ca,4Mn]) by reductants like hydroquinone (H 2Q) occurs with lower efficiency at acidic pH (2Mn/reaction center [RC] are extracted at pH 5.7) than at neutral pH (3Mn/RC are extracted at pH 6.5) [Semin et al. Photosynth. Res. 125 (2015) 95]. Fe(II) also extracts Mn cations from PSII(-Ca,4Mn), but only 2Mn/RC at pH 6.5, forming a heteronuclear 2Mn/2Fe cluster [Semin and Seibert, J. Bioenerg. Biomembr. 48 (2016) 227]. Here we investigated the efficiency of Mn extraction by Fe(II) at acidic pH and found that Fe(II) cations can extractmore » only 1Mn/RC from PSII(-Ca,4Mn) membranes at pH 5.7, forming a 3Mn/1Fe cluster.« less

Creation of a 3Mn/1Fe cluster in the oxygen-evolving complex of photosystem II and investigation of its functional activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semin, B. K.; Davletshina, L. N.; Seibert, M.

Extraction of Mn cations from the oxygen-evolving complex (OEC) of Ca-depleted PSII membranes (PSII[-Ca,4Mn]) by reductants like hydroquinone (H 2Q) occurs with lower efficiency at acidic pH (2Mn/reaction center [RC] are extracted at pH 5.7) than at neutral pH (3Mn/RC are extracted at pH 6.5) [Semin et al. Photosynth. Res. 125 (2015) 95]. Fe(II) also extracts Mn cations from PSII(-Ca,4Mn), but only 2Mn/RC at pH 6.5, forming a heteronuclear 2Mn/2Fe cluster [Semin and Seibert, J. Bioenerg. Biomembr. 48 (2016) 227]. Here we investigated the efficiency of Mn extraction by Fe(II) at acidic pH and found that Fe(II) cations can extractmore » only 1Mn/RC from PSII(-Ca,4Mn) membranes at pH 5.7, forming a 3Mn/1Fe cluster.« less

Manganese speciation of laboratory-generated welding fumes

PubMed Central

Andrews, Ronnee N.; Keane, Michael; Hanley, Kevin W.; Feng, H. Amy; Ashley, Kevin

2015-01-01

The objective of this laboratory study was to identify and measure manganese (Mn) fractions in chamber-generated welding fumes (WF) and to evaluate and compare the results from a sequential extraction procedure for Mn fractions with that of an acid digestion procedure for measurement of total, elemental Mn. To prepare Mn-containing particulate matter from representative welding processes, a welding system was operated in short circuit gas metal arc welding (GMAW) mode using both stainless steel (SS) and mild carbon steel (MCS) and also with flux cored arc welding (FCAW) and shielded metal arc welding (SMAW) using MCS. Generated WF samples were collected onto polycarbonate filters before homogenization, weighing and storage in scintillation vials. The extraction procedure consisted of four sequential steps to measure various Mn fractions based upon selective solubility: (1) soluble Mn dissolved in 0.01 M ammonium acetate; (2) Mn (0,II) dissolved in 25 % (v/v) acetic acid; (3) Mn (III,IV) dissolved in 0.5% (w/v) hydroxylamine hydrochloride in 25% (v/v) acetic acid; and (4) insoluble Mn extracted with concentrated hydrochloric and nitric acids. After sample treatment, the four fractions were analyzed for Mn by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). WF from GMAW and FCAW showed similar distributions of Mn species, with the largest concentrations of Mn detected in the Mn (0,II) and insoluble Mn fractions. On the other hand, the majority of the Mn content of SMAW fume was detected as Mn (III,IV). Although the concentration of Mn measured from summation of the four sequential steps was statistically significantly different from that measured from the hot block dissolution method for total Mn, the difference is small enough to be of no practical importance for industrial hygiene air samples, and either method may be used for Mn measurement. The sequential extraction method provides valuable information about the oxidation state of Mn in samples and allows for comparison to results from previous work and from total Mn dissolution methods. PMID:26345630

Manganese speciation of laboratory-generated welding fumes.

PubMed

Andrews, Ronnee N; Keane, Michael; Hanley, Kevin W; Feng, H Amy; Ashley, Kevin

The objective of this laboratory study was to identify and measure manganese (Mn) fractions in chamber-generated welding fumes (WF) and to evaluate and compare the results from a sequential extraction procedure for Mn fractions with that of an acid digestion procedure for measurement of total, elemental Mn. To prepare Mn-containing particulate matter from representative welding processes, a welding system was operated in short circuit gas metal arc welding (GMAW) mode using both stainless steel (SS) and mild carbon steel (MCS) and also with flux cored arc welding (FCAW) and shielded metal arc welding (SMAW) using MCS. Generated WF samples were collected onto polycarbonate filters before homogenization, weighing and storage in scintillation vials. The extraction procedure consisted of four sequential steps to measure various Mn fractions based upon selective solubility: (1) soluble Mn dissolved in 0.01 M ammonium acetate; (2) Mn (0,II) dissolved in 25 % (v/v) acetic acid; (3) Mn (III,IV) dissolved in 0.5% (w/v) hydroxylamine hydrochloride in 25% (v/v) acetic acid; and (4) insoluble Mn extracted with concentrated hydrochloric and nitric acids. After sample treatment, the four fractions were analyzed for Mn by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). WF from GMAW and FCAW showed similar distributions of Mn species, with the largest concentrations of Mn detected in the Mn (0,II) and insoluble Mn fractions. On the other hand, the majority of the Mn content of SMAW fume was detected as Mn (III,IV). Although the concentration of Mn measured from summation of the four sequential steps was statistically significantly different from that measured from the hot block dissolution method for total Mn, the difference is small enough to be of no practical importance for industrial hygiene air samples, and either method may be used for Mn measurement. The sequential extraction method provides valuable information about the oxidation state of Mn in samples and allows for comparison to results from previous work and from total Mn dissolution methods.

Variation of the coordination environment and its effect on the white light emission properties in a Mn-doped ZnO-ZnS complex structure.

PubMed

Cheng, Yan; Chen, Rui; Feng, Haifeng; Hao, Weichang; Xu, Huaizhe; Wang, Yu; Li, Jiong

2014-03-14

Mn-doped ZnO-ZnS complex nanocrystals were fabricated through coating of dodecanethiol on Mn-doped ZnO nanocrystals. The relationship between the component of white light emission and the coordination environments of Mn-dopants were experimentally investigated. It was shown that Mn ions mainly formed Mn(3+)O6 octahedra in as prepared Mn-doped ZnO, while the Mn(3+) ions on the surface of ZnO transferred into Mn(2+) ions at the interface between ZnO and ZnS after dodecanethiol coating. The Mn(2+)S4 tetrahedron density and the orange emission intensity increased upon enhancing the dodecanethiol content. These results provide an alternative way to optimize the white emission spectrum from nanocrystals of Mn-doped ZnS-ZnO complex structures through modulation of the coordination environment of Mn ions.

Manipulation of Dy-Mn coupling and ferrielectric phase diagram of DyMn2O5: The effect of Y substitution of Dy

NASA Astrophysics Data System (ADS)

Zhao, Z. Y.; Wang, Y. L.; Lin, L.; Liu, M. F.; Li, X.; Yan, Z. B.; Liu, J.-M.

2015-11-01

DyMn2O5 is an extraordinary example in the family of multiferroic manganites and it accommodates both the 4f and 3d magnetic ions with strong Dy-Mn (4f-3d) coupling. The electric polarization origin is believed to arise not only from the Mn spin interactions but also from the Dy-Mn coupling. Starting from proposed scenario on ferrielectricity in DyMn2O5 where the exchange-strictions associated with the Mn3+-Mn4+-Mn3+ blocks and Dy3+-Mn4+-Dy3+ blocks generate the two ferroelectric sublattices, we perform a set of characterizations on the structure, magnetism, and electric polarization of Dy1-xYxMn2O5 in order to investigate the roles of Dy-Mn coupling in manipulating the ferrielectricity. It is revealed that the non-magnetic Y substitution of Dy suppresses gradually the Dy3+ spin ordering and the Dy-Mn coupling. Consequently, the ferroelectric sublattice generated by the exchange striction associated with the Dy3+-Mn4+-Dy3+ blocks is destabilized, but the ferroelectric sublattice generated by the exchange striction associated with the Mn3+-Mn4+-Mn3+ blocks remains less perturbed, enabling the ferrielectricity-ferroelectricity transitions with the Y substitution. A phenomenological ferrielectric domain model is suggested to explain the polarization reversal induced by the Y substitution. The present work presents a possible scenario of the multiferroic mechanism in not only DyMn2O5 but probably also other RMn2O5 members with strong 4f-3d coupling.

Vaporization thermodynamic studies by high-temperature mass spectrometry on some three-phase regions over the MnO-TeO2 binary line in the Mn-Te-O ternary system.

PubMed

Narasimhan, T S Lakshmi; Sai Baba, M; Viswanathan, R

2006-12-28

Knudsen effusion mass spectrometric measurements have been performed in the temperature range of 850-950 K over four three-phase mixtures, each phase mixture having at least one phase lying on the MnO-TeO2 binary line of the Mn-Te-O phase diagram, and the rest of the phases lying above this binary line. The three-phase mixtures investigated are Mn3O4 + MnO + Mn6Te5O16; Mn3O4 + Mn6Te5O16 + MnTeO3; Mn3O4 + Mn3TeO6 + MnTeO3; and Mn3TeO6 + MnTeO3 + Mn2Te3O8. The vapor pressures of the gaseous species TeO2, TeO, and Te2 over these three-phase mixtures were measured, and various heterogeneous solid-gas reactions were evaluated along with the homogeneous gas-phase reaction TeO2(g) + 0.5Te2(g) = 2 TeO(g). The enthalpy and Gibbs free energy of formation of the four ternary Mn-Te-O phases were deduced at T = 900 K. These values (in kJ.mol-1), along with the estimated uncertainties in them are Delta(f)H(o)m = 4150 +/- 19, 752 +/- 11, 1710 +/- 11, 1924 +/- 40, and Delta(f)G(o)m= 2835 +/- 28, 511 +/- 11, 1254 +/- 19, 1238 +/- 38, for Mn6Te5O16, MnTeO3, Mn3TeO6, and Mn2Te3O8, respectively. A thermochemical assessment was made to examine the conditions under which the ternary Mn-Te-O phases could be formed on a stainless steel clad of mixed-oxide-fueled (MO2; M = U + Pu) fast breeder nuclear reactors. The phase Mn3TeO6 could be formed when the fuel is even slightly hyperstoichiometric (O/M = 2.0002) and the phase Mn6Te5O16 could also be formed when O/M = 2.0004. The threshold tellurium potential for the formation of Mn3TeO6 is higher than that for MnTe0.80 and CrTe1.10, but is comparable to that for MoTe1.10, and even lower than that for FeTe0.81 or NiTe0.63.

Substituting Fe for two of the four Mn ions in photosystem II-effects on water-oxidation.

PubMed

Semin, Boris K; Seibert, Michael

2016-06-01

We have investigated the interaction of Fe(II) cations with Ca-depleted PSII membranes (PSII[-Ca,4Mn]) in the dark and found that Fe(II) incubation removes 2 of 4 Mn ions from the tetranuclear Mn cluster of the photosynthetic O2-evolving complex (OEC). The reduction of Mn ions in PSII(-Ca,4Mn) by Fe(II) and the concomitant release of two Mn(II) cations is accompanied by the binding of newly generated Fe(III) in at least one vacated Mn site. Flash-induced chlorophyll (Chl) fluorescence yield measurements of this new 2Mn/nFe cluster (PSII[-Ca,2Mn,nFe]) show that charge recombination in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) occurs between Qa (-) and the remaining Mn/Fe cluster (but not YZ (●)) in the OEC, and extraction of 2 Mn occurs uniformly in all PSII complexes. No O2 evolution is observed, but the heteronuclear metal cluster in PSII(-Ca,2Mn,nFe) samples is still able to supply electrons for reduction of the exogenous electron acceptor, 2,6-dichlorophrenolindophenol, by photooxidizing water and producing H2O2 in the absence of an exogenous donor as seen previously with PSII(-Ca,4Mn). Selective extraction of Mn or Fe cations from the 2Mn/nFe heteronuclear cluster demonstrates that the high-affinity Mn-binding site is occupied by one of the iron cations. It is notable that partial water-oxidation function still occurs when only two Mn cations are present in the PSII OEC.

Nucleation/Growth Mechanisms and Morphological Evolution of Porous MnO₂ Coating Deposited on Graphite for Supercapacitor.

PubMed

Huang, Wenxin; Li, Jun; Xu, Yunhe

2017-10-19

The nucleation and growth mechanisms of porous MnO₂ coating deposited on graphite in MnSO₄ solution were investigated in detail by cyclic voltammetry, chronoamperometry and scanning electron microscopy. The electrochemical properties of honeycomb-like MnO₂ were evaluated by cycle voltammetry and galvanostatic charge-discharge. Results indicated that MnO₂ was synthesized by the following steps: Mn 2+ → Mn 3+ + e⁻, Mn 3+ +2H2O → MnOOH + 3H⁺, and MnOOH → MnO₂ + H⁺+ e⁻. The deposition of MnO₂ was divided into four stages. A short incubation period (approximately 1.5 s) was observed, prior to nucleation. The decreasing trend of the current slowed as time increased due to nucleation and MnO₂ growth in the second stage. A huge number of nuclei were formed by instantaneous nucleation, and these nuclei grew and connected with one another at an exceedingly short time (0.5 s). In the third stage, the gaps in-between initial graphite flakes were filled with MnO₂ until the morphology of the flakes gradually became similar to that of the MnO₂-deposited layer. In the fourth stage, the graphite electrode was covered completely with a thick and dense layer of MnO₂ deposits. All MnO₂ electrodes at different deposition times obtained nearly the same specific capacitance of approximately 186 F/g, thus indicating that the specific capacitance of the electrodes is not related with deposition time.

In-field X-ray and neutron diffraction studies of re-entrant charge-ordering and field induced metastability in La0.175Pr0.45Ca0.375MnO3-δ

NASA Astrophysics Data System (ADS)

Sharma, Shivani; Shahee, Aga; Yadav, Poonam; da Silva, Ivan; Lalla, N. P.

2017-11-01

Low-temperature high-magnetic field (2 K, 8 T) (LTHM) powder X-ray diffraction (XRD) and time of flight powder neutron diffraction (NPD), low-temperature transmission electron microscopic (TEM), and resistivity and magnetization measurements have been carried out to investigate the re-entrant charge ordering (CO), field induced structural phase transitions, and metastability in phase-separated La0.175Pr0.45Ca0.375MnO3-δ (LPCMO). Low-temperature TEM and XRD studies reveal that on cooling under zero-field, paramagnetic Pnma phase transforms to P21/m CO antiferromagnetic (AFM) insulating phase below ˜233 K. Unlike reported literature, no structural signature of CO AFM P21/m to ferromagnetic (FM) Pnma phase-transition during cooling down to 2 K under zero-field was observed. However, the CO phase was found to undergo a re-entrant transition at ˜40 K. Neutron diffraction studies revealed a pseudo CE type spin arrangement of the observed CO phase. The low-temperature resistance, while cooled under zero-field, shows insulator to metal like transition below ˜105 K with minima at ˜25 K. On application of field, the CO P21/m phase was found to undergo field-induced transition to FM Pnma phase, which shows irreversibility on field removal below ˜40 K. Zero-field warming XRD and NPD studies reveal that field-induced FM Pnma phase is a metastable phase, which arise due to the arrest of kinetics of the first-order phase transition of FM Pnma to CO-AFM P21/m phase, below 40 K. Thus, a strong magneto-structural coupling is observed for this system. A field-temperature (H-T) phase-diagram has been constructed based on the LTHM-XRD, which matches very nicely with the reported H-T phase-diagram constructed based on magnetic measurements. Due to the occurrence of gradual growth of the re-entrant CO phase and the absence of a clear structural signature of phase-separation of CO-AFM P21/m and FM Pnma phases, the H-T minima in the phase-diagram of the present LPCMO sample has been attributed to the strengthening of AFM interaction during re-entrant CO transition and not to glass like "dynamic to frozen" transition.

Effect of Ir-Mn composition on exchange bias and thermal stability of spin valves with nano-oxide layers

NASA Astrophysics Data System (ADS)

Liu, Y. F.; Cai, J. W.; Lai, W. Y.; Yu, G. H.

2008-05-01

The Ir-Mn bottom-pinned spin valves with nano-oxide layers (NOLs), Ta /Ni81Fe19/Ir-Mn/Co90Fe10/NOL/Co90Fe10/Cu/Co90Fe10/NOL/Ta, were fabricated by dc magnetron sputtering. The magnetoresistance (MR), magnetization, and exchange bias have been studied as a function of Ir-Mn composition and annealing temperature. It was observed that the spin valves with the Ir-Mn layer containing relatively low Mn content (58.9-72.4at.% Mn) show the best thermal endurance. For these samples, the Mn diffusion is effectively hampered by the NOL with a large MR value of about 12.5% even after annealing at 300°C. On the other hand, the exchange bias field of the pinned CoFe layer shows a maximum at Mn content of about 72.4at.%, which is different from the widely adopted composition, Ir-80at.% Mn, optimized from the top-pinned NiFe /Ir-Mn system. Moreover, the blocking temperature of the Ir -Mn/CoFe system with 72.4at.% Mn is higher than that with 80.6at.% Mn. The present results suggest that the Ir -Mn/CoFe pinning system with Mn content at about 72% renders the most favorable exchange bias and the best thermal stability for the bottom-pinned specular spin valves.

Blood manganese as an exposure biomarker: State of the evidence

PubMed Central

Baker, Marissa G.; Simpson, Christopher D.; Stover, Bert; Sheppard, Lianne; Checkoway, Harvey; Racette, Brad A.; Seixas, Noah S.

2014-01-01

Despite evidence of adverse health effects resulting from exposure to manganese (Mn), biomarkers of exposure are poorly understood. To enhance understanding, mean blood Mn (MnB) and mean air Mn (MnA) were extracted from 63 exposure groups in 24 published papers, and the relationship was modeled using segmented regression. On a log/log scale, a positive association between MnA and MnB was observed among studies reporting MnA concentrations above about 10 μg/m3, although interpretation is limited by largely cross-sectional data, study design variability, and differences in exposure monitoring methods. Based on the results of the segmented regression, we hypothesize that below the concentration of about 10 μg/m3, Mn in the body is dominated by dietary Mn, and additional inhaled Mn only causes negligible changes in Mn levels unless the inhaled amount is substantial. However, stronger study designs are required to account for temporal characteristics of the MnA to MnB relationships which reflect the underlying physiology and toxicokinetics of Mn uptake and distribution. Thus, we present an inception cohort study design we have conducted among apprentice welders, and the analytical strengths this study design offers. To determine if blood could be a useful biomarker for Mn to be utilized by industrial hygienists in general industry requires additional time-specific analyses, which our inception cohort study design will allow. PMID:24579750

Kinetics of α-MnOOH Nanoparticle Formation through Enzymatically Catalyzed Biomineralization inside Apoferritin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hui, Yue; Jung, Haesung; Kim, Doyoon

While biomineralization in apoferritin has effectively synthesized highly monodispersed nanoparticles of various metal oxides and hydroxides, the detailed kinetics and mechanisms of Mn(III) (hydr)oxide formation inside apoferritin cavities have not been reported. To address this knowledge gap, we first identified the phase of solid Mn(III) formed inside apoferritin cavities as α-MnOOH. To analyze the oxidation and nucleation mechanism of α-MnOOH inside apoferritin by quantifying oxidized Mn, we used a colorimetric method with leucoberbelin blue (LBB) solution. In this method, LBB disassembled apoferritin by inducing an acidic pH environment, and reduced α-MnOOH nanoparticles. The LBB-enabled kinetic analyses of α-MnOOH nanoparticle formationmore » suggested that the orders of reaction with respect to Mn2+ and OH– are 2 and 4, respectively, and α-MnOOH formation follows two-step pathways: First, soluble Mn2+ undergoes apoferritin-catalyzed oxidation at the ferroxidase dinuclear center, forming a Mn(III)-protein complex, P-[Mn2O2(OH)2]. Second, the oxidized Mn(III) dissociates from the protein binding sites and is subsequently nucleated to form α-MnOOH nanoparticles in the apoferritin cavities. This study reveals key kinetics and mechanistic information on the Mn-apoferritin systems, and the results facilitate applications of apoferritin as a means of nanomaterial synthesis.« less

Bi-template assisted synthesis of mesoporous manganese oxide nanostructures: Tuning properties for efficient CO oxidation.

PubMed

Roy, Mouni; Basak, Somjyoti; Naskar, Milan Kanti

2016-02-21

A simple soft bi-templating process was used for the synthesis of mesoporous manganese oxide nanostructures using KMnO4 as a precursor and polyethylene glycol and cetyltrimethylammonium bromide as templates in the presence of benzaldehyde as an organic additive in alkaline media, followed by calcination at 400 °C. X-ray diffraction and Raman spectroscopic analysis of the calcined products confirmed the existence of stoichiometric (MnO2 and Mn5O8) and non-stoichiometric mixed phases (MnO2 + Mn5O8) of Mn oxides obtained by tuning the concentration of the additive and the synthesis time. The surface properties of the prepared Mn oxides were determined by X-ray photoelectron spectroscopy. The mesoporosity of the samples was confirmed by N2 adsorption-desorption. Different synthetic conditions resulted in the formation of different morphologies of the Mn oxides (α-MnO2, Mn5O8, and α-MnO2 + Mn5O8), such as nanoparticles, nanorods, and nanowires. The synthesized mesoporous Mn oxide nanostructures were used for the catalytic oxidation of the harmful air pollutant carbon monoxide. The Mn5O8 nanoparticles with the highest Brunauer-Emmett-Teller surface area and the non-stoichiometric manganese oxide (α-MnO2 + Mn5O8) nanorods with a higher Mn(3+) concentration had the best catalytic efficiency.

Icosahedral quasicrystal Al71Pd21Mn08 and its ξ' approximant: Linear expansivity, specific heat, magnetic susceptibility, electrical resistivity, and elastic constants

NASA Astrophysics Data System (ADS)

Swenson, C. A.; Fisher, I. R.; Anderson, N. E.; Canfield, P. C.; Migliori, A.

2002-05-01

Linear thermal expansivity (α, 1-300 K), heat capacity (Cp, 1-108 K), magnetic susceptibility (χ, 1-300 K), and electrical resistivity (ρ, 1-300 K) measurements are reported for a single-grain i-Al71Pd21Mn08 quasicrystal and its Al72Pd25Mn03 approximant, and 300 K elastic constants for the quasicrystal. The approximant α (αAp) and Cp (CpAp) data show ``metallic'' behavior, while the previously reported onset of a transition to a spin-glass state (Tf<1.8 K) dominates αQ and CpQ below 11 K. CpAp and CpQ superimpose above 16 K when plotted vs T/Θ0 using the experimental Θ0Ap=455(3) K and an adjusted Θ0ApQ=480(4) K. The 300 K elastic constants extrapolated to T=0 give Θel0Q=505(1) K, suggesting that the normalization is valid only above 16 K. The lattice contribution to CpAp (and, indirectly, CpQ) shows strong (unique) deviations from Debye-like behavior (+3% at 0.84 K for the CpAp data fit). The various Grüneisen parameters (Γ) that are calculated from these data all are positive and normal in magnitude except for a large limiting approximant lattice value, Γlat0Ap=11.3, which may be related to the large dispersion effects in Cp. For the approximant, the combination of anisotropic and large resistivities, a small diamagnetic susceptibility, and a ``large'' linear (electronic) contribution to CpAp (γAp=0.794 mJ/mol K2) suggests the existence of a pseudogap in the electronic density of states. The unusually large, highly volume dependent, dispersion at low temperatures for the quasicrystal and its approximant are not consistent with inelastic neutron scattering and other data, and raise questions about the role of phonons in quasicrystals. The present 300 K resistivities can be used with a published correlation to estimate γQ~0.25 mJ/mol K2.

Enhanced Cycleability of Amorphous MnO2 by Covering on α-MnO2 Needles in an Electrochemical Capacitor

PubMed Central

Liu, Quanbing; Yang, Juan; Wang, Hui; Pollet, Bruno G.; Wang, Rongfang

2017-01-01

An allomorph MnO2@MnO2 core-shell nanostructure was developed via a two-step aqueous reaction method. The data analysis of Scanning Electron Microscopy, Transmission Electron Microscopy, X-Ray Diffraction and N2 adsorption-desorption isotherms experiments indicated that this unique architecture consisted of a porous layer of amorphous-MnO2 nano-sheets which were well grown onto the surface of α-MnO2 nano-needles. Cyclic voltammetry experiments revealed that the double-layer charging and Faradaic pseudo-capacity of the MnO2@MnO2 capacitor electrode contributed to a specific capacitance of 150.3 F·g−1 at a current density of 0.1 A·g−1. Long cycle life experiments on the as-prepared MnO2@MnO2 sample showed nearly a 99.3% retention after 5000 cycles at a current density of 2 A·g−1. This retention value was found to be significantly higher than those reported for amorphous MnO2-based capacitor electrodes. It was also found that the remarkable cycleability of the MnO2@MnO2 was due to the supporting role of α-MnO2 nano-needle core and the outer amorphous MnO2 layer. PMID:28837099

Structure and magnetic properties of L10-MnGa nanoparticles prepared using direct reactions between Mn nanoparticles and Ga

NASA Astrophysics Data System (ADS)

Si, P. Z.; Qian, H. D.; Park, J.; Ge, H. L.; Shinde, K. P.; Chung, K. C.; Choi, C. J.

2018-05-01

The tetragonal L10-Mn1+xGa (x<0.8) nanoparticles and bcc-Mn23Ga77 nanoparticles with large coercivity were prepared using direct reactions between Mn nanoparticles and Ga at elevated temperatures. The Mn23Ga77 phase was formed at ˜573 K while the L10-structured Mn1+xGa was formed at ˜850 K. After ball-milling, the L10-Mn1+xGa nanoparticles transformed into nano-flakes with enhanced coercivity. The size of the as-prepared Mn23Ga77 nanoparticles is comparable to that of the precursor Mn nanoparticles. An aggregation of the nanoparticles and thus a larger particle size were observed in the L10-Mn1+xGa nanoparticles obtained at 850 K. The size of the L10-Mn1+xGa nano-flakes is reduced to about 200-400 nm with a thickness of ˜20 nm. The coercivity of the Mn23Ga77 nanoparticles and the L10-Mn1+xGa nanoparticles at 300 K reached up to 0.2 T and 0.43 T, respectively. The coercivity of L10-Mn1+xGa ball-milled nano-flakes is 0.59 T at 300 K.

Kinetic Investigations of SiMn Slags From Different Mn Sources

NASA Astrophysics Data System (ADS)

Kim, Pyunghwa Peace; Tangstad, Merete

2018-06-01

The kinetics of MnO and SiO2 reduction were investigated for Silicomanganese (SiMn) slags using a Thermogravimetric analysis (TGA) between 1773 K and 1923 K (1500 °C and 1650 °C) under CO atmospheric pressure. The charge materials were based on Assmang ore and HC FeMn Slag. Rate models for MnO and SiO2 reduction were applied to describe the metal-producing rates, as shown by the following equations: r_{MnO} = k_{MnO} × A × ( {a_{MnO} - {a_{Mn} }/{K_{T }}} ) r_{{{SiO}2 }} = k_{SiO2} × A × ( {a_{{{SiO}2 }} - {a_{Si} }/{K_{T }}} ). The results show that the choice of raw materials in the charge considerably affected the reduction rate of MnO and SiO2. The highest reduction rate was found to be from charges using HC FeMn slag. The difference in the driving forces was insignificant among the SiMn slags, and the similar slag viscosities could not explain the different reduction rates. Instead, the difference is attributed to small amounts of sulfur and the amount of iron in the charge. In addition, the rate models were applicable to describe the reduction of MnO and SiO2 in SiMn slags.

A facile synthesis of α-MnO2 used as a supercapacitor electrode material: The influence of the Mn-based precursor solutions on the electrochemical performance

NASA Astrophysics Data System (ADS)

Li, Wenyao; Xu, Jiani; Pan, Yishuang; An, Lei; Xu, Kaibing; Wang, Guangjin; Yu, Zhishui; Yu, Li; Hu, Junqing

2015-12-01

Three types of α-MnO2 nanomaterials are synthesized in different Mn-based precursor solutions by using a facile electrochemical deposition at the same depositional condition. The relationships between the precursor solutions and corresponding MnO2 nanomaterials' morphology as well as the electrochemical performance have been studied. As an electrode, electrochemical measurements show that the MnO2 deposited in MnCl2 precursor solution (MnO2-P3) exhibits an enhanced specific capacitance (318.9 F g-1 at 2 mV s-1). Moreover, this electrode demonstrates a good rate capability with 44% retention, which is higher than the MnO2-P1 deposited with Mn(CH3COOH)2 solution and the MnO2-P2 deposited with Mn(NO3)2 precursor solution. Besides, the specific capacitance of the MnO2-P3 electrode nearly has 98.2% retention after 2000 cycles, showing good long-term cycle stability. These findings show that the MnO2-P3 is a promising electrode material for supercapacitors.

Effect of Fe-Mn addition on microstructure and magnetic properties of NdFeB magnetic powders

NASA Astrophysics Data System (ADS)

Kurniawan, C.; Purba, A. S.; Setiadi, E. A.; Simbolon, S.; Warman, A.; Sebayang, P.

2018-03-01

In this paper, the effect of Fe-Mn alloy addition on microstructures and magnetic properties of NdFeB magnetic powders was investigated. Varied Fe-Mn compositions of 1, 5, and 10 wt% were mixed with commercial NdFeB type MQA powders for 15 minutes using shaker mill. The characterizations were performed by powder density, PSA, XRD, SEM, and VSM. The Fe-Mn addition increased the powder density of NdFeB/Fe-Mn powders. On the other side, particle size distribution slightly decreased as the Fe-Mn composition increases. Magnetic properties of NdFeB/Fe-Mn powders changed with the increasing of Fe-Mn content. SEM analysis showed the particle size of NdFeB/Fe-Mn powder was smaller as the Fe-Mn composition increases. It showed that NdFeB/Fe-Mn particles have different size and shape for NdFeB and Fe-Mn particles separately. The optimum magnetic properties of NdFeB/Fe-Mn powder was achieved on the 5 wt% Fe-Mn composition with remanence M r = 49.45 emu/g, coercivity H c = 2.201 kOe, and energy product, BH max = 2.15 MGOe.

Perpendicular magnetic tunnel junctions with Mn-modified ultrathin MnGa layer

NASA Astrophysics Data System (ADS)

Suzuki, K. Z.; Miura, Y.; Ranjbar, R.; Bainsla, L.; Ono, A.; Sasaki, Y.; Mizukami, S.

2018-02-01

Perpendicular magnetic tunnel junctions (p-MTJs) with a MgO barrier and a 1-nm-thick MnGa electrode were investigated by inserting several monolayers (MLs) of Mn. The tunnel magnetoresistance (TMR) ratio systematically increased when increasing the Mn layer thickness with a maximum of 18 (38.4)% at 300 (5) K for a Mn layer thickness of 0.6-0.8 nm. This ratio is five times higher compared to that without the Mn layer. The perpendicular magnetic anisotropy (PMA) field and the PMA constant of the ultrathin MnGa layer also increased up to 62-90 kOe and 6.2-11.3 Merg/cm3, respectively, with an increase in the Mn interlayer thickness, even for the ultrathin regime of the MnGa layer. For p-MTJs showing a high TMR and PMA, electron microscopy indicated the presence of 3-4 MLs of Mn at the MnGa/MgO interface; thus, the Mn modification enhanced the TMR as well as improved the PMA. This may be a promising finding to develop a Mn-based free layer for spin-transfer-torque devices for high-recording-density magnetoresistive random access memory and a sub-THz oscillator/detector.

Effect of source of trace minerals in either forage- or by-product-based diets fed to dairy cows: 2. Apparent absorption and retention of minerals.

PubMed

Faulkner, M J; St-Pierre, N R; Weiss, W P

2017-07-01

Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of source of supplemental Cu, Zn, and Mn (sulfates or hydroxy) on apparent absorption of minerals when fed in either a forage- or by-product-based diet. The by-product diets were formulated to have greater concentrations of NDF and lesser concentrations of starch, and specific ingredients were chosen because they were good sources of soluble fiber and β-glucans, which bind trace minerals in nonruminants. We hypothesized that hydroxy trace minerals would interact less with digesta and have greater apparent absorption compared with sulfate minerals, and the difference in apparent absorption would be greater for the by-product diet compared with the forage-based diet. During the 56-d experiment, cows remained on the same fiber treatment but source of supplemental trace mineral was different for each 28-d period; thus, all cows were exposed to both mineral treatments. During each period cows were fed no supplemental Cu, Zn, or Mn for 16 d, followed by 12 d of feeding supplemental minerals from either sulfate or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total Cu, Zn, and Mn dietary concentrations, respectively, were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 for the by-product diets. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Cows consuming the by-product diets had greater Zn (1,863 vs. 1,453 mg/d) and Mn (1,790 vs. 1,588 mg/d) intake compared with cows fed forage diets, but apparent Zn absorption was similar between treatments. Manganese apparent absorption was greater for the by-product diets compared with the forage diets (16 vs. 11%). A fiber by mineral interaction was observed for Cu apparent absorption, as cows fed hydroxy minerals with forage diets had greater apparent absorption compared with cows fed sulfate minerals; however, the opposite was observed with the by-product diets. Source of supplemental trace minerals and type of fiber in diets affected availability of Cu and Mn and should be considered in ration formulation. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effect of source of trace minerals in either forage- or by-product-based diets fed to dairy cows: 1. Production and macronutrient digestibility.

PubMed

Faulkner, M J; Weiss, W P

2017-07-01

Excess rumen-soluble Cu and Zn can alter rumen microbial populations and reduce fiber digestibility. Because of differences in particle size and chemical composition, ruminal and total-tract digestibility of fiber from forage- and by-product-based diets can differ. We hypothesized that, because of differences in mineral solubility, diets with hydroxy rather than sulfate trace minerals would have greater fiber digestibility, but the effect may depend on source of fiber. Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of Cu, Zn, and Mn source (sulfates or hydroxy; Micronutrients USA LLC, Indianapolis, IN) and neutral detergent fiber (NDF) source (forage diet = 26% NDF vs. by-product = 36%) on total-tract nutrient digestibility. During the entire experiment (56 d) cows remained on the same fiber treatment, but source of supplemental trace mineral was different for each 28-d period so that all cows were exposed to both mineral treatments. During each of the two 28-d periods, cows were fed no supplemental Cu, Zn, or Mn for 16 d followed by 12 d of feeding supplemental Cu, Zn, and Mn from either sulfates or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total dietary concentrations of Cu, Zn, and Mn were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 mg/kg for the by-product diets, respectively. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Milk fatty acid profiles were altered by fiber source, mineral source, and their interaction. Cows fed the by-product diets had lower dry matter (65.9 vs. 70.2%), organic matter (67.4 vs. 71.7%), and crude protein digestibility (58.8 vs. 62.1%) but greater starch (97.5 vs. 96.3%) and NDF digestibility (50.5 vs. 44.4%) compared with cows fed the forage treatment. Feeding increased concentrations of by-products decreased total digestible nutrients regardless of mineral source. Feeding hydroxy Cu, Zn, and Mn increased NDF digestibility (48.5 vs. 46.4%) but had no effect on total digestible nutrients. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Combining cross flow ultrafiltration and diffusion gradients in thin-films approaches to determine trace metal speciation in freshwaters

NASA Astrophysics Data System (ADS)

Liu, Ruixia; Lead, Jamie R.; Zhang, Hao

2013-05-01

Cross flow ultrafiltration (CFUF) and diffusive gradients in thin films (DGT) with open pore gel (OP) and restricted pore gel (RP) were used to measure trace metal speciation in selected UK freshwaters. The proportions of metals present in particulate forms (>1 μm) varied widely between 40-85% Pb, 60-80% Al, 7-56% Mn, 10-49% Cu, 0-55% Zn, 20-38% Cr, 20-30% Fe, 6-25% Co, 5-22% Cd and <7% Ni. In the colloidal fraction (2 kDa-1 μm) values varied between 53-91% Pb, 33-55% Al, 21-55% Cu, 20-44% Fe, 34-36% Cr, 20-40% Cd, 7-28% Co and Ni, 2-32% Zn and <8% Mn. Wide variations were also observed in the ultrafiltered fraction (<2 kDa). These results indicated that colloids indeed influenced the occurrence and transport of Al, Fe, Cr, Co, Ni, Cu, Zn, Cr and Pb metals in rivers, while inorganic or organic colloids did not exert an important control on Mn transport in the selected freshwaters. Of total species, total labile metal measured by DGT-OP accounted for 1.4-50% for Al, Fe, Co, Ni, Cu, Cd and Pb in all selected waters. Of these metals total labile Pb concentration was the lowest with value less than 1.4% although this value slightly increased after deducting particulate fractions. In some waters, a majority of total Mn, Zn and Cr is DGT labile, in which the DGT labile Mn fraction accounted for 98-118% of the total dissolved phase. In most cases, the inorganic labile concentration measured by DGT-RP was lower than the total labile metal concentration. By the combination of CFUF and DGT techniques, the concentrations of total labile and inorganic labile metal species in CFUF-derived truly dissolved phase were measured in four water samples. 100% of ultrafiltered Mn species was found to be total DGT labile. The proportions of total labile metal species were lower than those of ultrafiltered fraction for Al, Fe, Co, Ni, Cu, Cd and Pb in all selected waters, and Cr and Zn in some cases, indicating a large amount of natural complexing ligands with smaller size for the metals to form kinetically inert species or thermodynamically stable complexes. Observed discrepancies in metal speciation between metals and within sampling sites were related to the differences in the characteristics of the metals and the nature of water sources.

Soluble Manganese(III) in the Marine Environment

NASA Astrophysics Data System (ADS)

Luther, G. W., III; Oldham, V.; Madison, A.; Tebo, B.; Jones, M.; Jensen, L.; Owings, S.; Mucci, A.; Sundby, B.

2014-12-01

Recent field studies have confirmed the presence of soluble manganese(III), which along with Mn(II) passes through a 0.2 μm filter, in suboxic marine waters. Here we applied a spectrophotometric method using a soluble porphyrin as a competitive ligand to calculate the concentrations and kinetics of Mn(II) and Mn(III) recovery. Data will be presented from the suboxic porewaters of the Saint Lawrence estuary, the suboxic and anoxic waters of the Chesapeake Bay and the oxygenated surface waters of a coastal waterway bordered by wetlands and salt marshes in Delaware. Soluble Mn(III) accounts for up to 100% of the dissolved Mn pool with concentrations ranging from the detection limit of 50 nM to 80 μM at the oxic/anoxic interface of the non-sulfidic porewaters from the hemipelagic sediments of the St. Lawrence Estuary. Data indicate weak-ligand complexation of Mn(III) formed from Mn(II) oxidation as well as reduction of MnO2. Complexation of Mn(III) in the anoxic waters of Chesapeake Bay appears stronger as the porphyrin could not outcompete the natural ligands binding Mn(III). Mn(III) complexes were reduced in the presence of hydroxylamine or hydrogen sulfide and detected as Mn(II). Soluble Mn(III) comprised up to 52 % of total dissolved Mn. Profiles over the course of a five day cruise showed that high Mn(III) concentrations (7.3 μM) were observed at low H2S (4.9 μM) whereas low Mn(III) (1.1 μM) was detected at high H2S (40 μM). The presence of Mn(III) in sulfidic waters indicated that it is kinetically stabilized in situ by strong ligands so reduction to Mn(II) was incomplete. One electron reductive dissolution of solid MnO2 particles formed at the oxic-anoxic interface appear to be the source of Mn(III). Lastly, soluble Mn(III) was detected in the oxygenated surface waters of a coastal waterway (salinity ranging from freshwater to 31) bordered by wetlands and salt marshes in Delaware. Soluble Mn(III) made up 0-49 % of the total dissolved Mn (maximum of 1.92 μM) with the highest concentrations and percentages coming from waters adjacent to salt marsh areas. The porphyrin competitive ligand could not outcompete the natural ligands, which appear to be humic material; thus, a reductant was again needed to convert the Mn(III) complexes to Mn(II) for measurement.

Magnetic properties of single-phase MnBi grown from MnBi{sub 49} melt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, X. F.; Si, P. Z., E-mail: pzsi@cjlu.edu.cn; Feng, H.

2014-05-07

The single-phase NiAs-type MnBi, embedded in Bi matrix, was grown from homogeneous MnBi{sub 49} melt at low temperatures to prevent the formation of Mn{sub 1.08}Bi. An abrupt magnetization change was observed at ∼240 K. The origin of this change was ascribed to the movement of the Mn atoms between the regular sites and the interstitial sites in the MnBi lattices. The splitting of the x-ray photoelectron lines of MnBi indicates the presence of two binding states of Mn atoms, one of which was ascribed to interstitial Mn atoms. A large coercivity up to 1.79 T at 400 K was observed in the as-grownmore » bulk isotropic MnBi alloys.« less

XPS and EELS characterization of Mn2SiO4, MnSiO3 and MnAl2O4

NASA Astrophysics Data System (ADS)

Grosvenor, A. P.; Bellhouse, E. M.; Korinek, A.; Bugnet, M.; McDermid, J. R.

2016-08-01

X-ray Photoelectron Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) are strong candidate techniques for characterizing steel surfaces and substrate-coating interfaces when investigating the selective oxidation and reactive wetting of advanced high strength steels (AHSS) during the continuous galvanizing process. However, unambiguous identification of ternary oxides such as Mn2SiO4, MnSiO3, and MnAl2O4 by XPS or EELS, which can play a significant role in substrate reactive wetting, is difficult due to the lack of fully characterized standards in the literature. To resolve this issue, samples of Mn2SiO4, MnSiO3 and MnAl2O4 were synthesized and characterized by XPS and EELS. The unique features of the XPS and EELS spectra for the Mn2SiO4, MnSiO3 and MnAl2O4 standards were successfully derived, thereby allowing investigators to fully differentiate and identify these oxides at the surface and subsurface of Mn, Si and Al alloyed AHSS using these techniques.

Transition metal redox and Mn disproportional reaction in LiMn0.5Fe0.5PO4 electrodes cycled with aqueous electrolyte

NASA Astrophysics Data System (ADS)

Zhuo, Zengqing; Hu, Jiangtao; Duan, Yandong; Yang, Wanli; Pan, Feng

2016-07-01

We performed soft x-ray absorption spectroscopy (sXAS) and a quantitative analysis of the transition metal redox in the LiMn0.5Fe0.5PO4 electrodes upon electrochemical cycling. In order to circumvent the complication of the surface reactions with organic electrolyte at high potential, the LiMn0.5Fe0.5PO4 electrodes are cycled with aqueous electrolyte. The analysis of the transitional metal L-edge spectra allows a quantitative determination of the redox evolution of Mn and Fe during the electrochemical cycling. The sXAS analysis reveals the evolving Mn oxidation states in LiMn0.5Fe0.5PO4. We found that electrochemically inactive Mn2+ is formed on the electrode surface during cycling. Additionally, the signal indicates about 20% concentration of Mn4+ at the charged state, providing a strong experimental evidence of the disproportional reaction of Mn3+ to Mn2+ and Mn4+ on the surface of the charged LiMn0.5Fe0.5PO4 electrodes.

[Application of ICP-MS to Identify the Botanic Source of Characteristic Honey in South Yunnan].

PubMed

Wei, Yue; Chen, Fang; Wang, Yong; Chen, Lan-zhen; Zhang, Xue-wen; Wang, Yan-hui; Wu, Li-ming; Zhou, Qun

2016-01-01

By adopting inductively coupled plasma mass spectrometry (ICP-MS) combined with chemometric analysis technology, 23 kinds of minerals in four kinds of characteristic honey derived from Yunnan province were analyzed. The result showed that 21 kinds of mineral elements, namely Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sb, Ba, Tl and Pb, have significant differences among different varieties of honey. The results of principal component analysis (PCA) showed that the cumulative variance contribution rate of the first four main components reached 77.74%, seven kinds of elements (Mg, Ca, Mn, Co, Sr, Cd, Ba) from the first main component contained most of the honey information. Through the stepwise discriminant analysis, seven kinds of elements (Mg, K, Ca, Cr, Mn, Sr, Pb) were filtered. out and used to establish the discriminant function model, and the correct classification rates of the proposed model reached 90% and 86.7%, respectively, which showed elements contents could be effectively indicators to discriminate the four kinds characteristic honey in southern Yunnan Province. In view of all the honey samples were harvested from apiaries located at south Yunnan Province where have similar climate, soil and other environment conditions, the differences of the mineral elements contents for the honey samples mainly due to their corresponding nectariferous plant. Therefore, it is feasible to identify honey botanical source through the differences of mineral elements.

Reentrant cluster glass and stability of ferromagnetism in the Ga2MnCo Heusler alloy

NASA Astrophysics Data System (ADS)

Samanta, Tamalika; Bhobe, P. A.; Das, A.; Kumar, A.; Nigam, A. K.

2018-05-01

We present here a detailed investigation into the magnetic ordering of a full Heusler alloy Ga2MnCo using dc and ac magnetization measurements, neutron diffraction, and neutron depolarization experiments. The crystal structure at room temperature was first confirmed to be L 21 using the highly intense synchrotron x-ray diffraction technique. Temperature-dependent magnetization reveals that Ga2MnCo enters a ferromagnetic (FM) state at TC=154 K, characterized by a sharp increase in magnetization and a plateaulike region hereafter. As the temperature is decreased further, a sharp drop in magnetization is observed at Tf=50 K, hinting toward an antiferromagnetic (AFM) phase change. Neutron diffraction (ND) recorded over the range of temperature from 6 to 300 K provides combined information regarding crystal as well as magnetic structure. Accordingly, an increase in the intensity of the ND pattern is seen at 150 K, signaling the onset of long-range FM order. However, there is no sign of the appearance of superlattice reflections corresponding to the AFM phase in the patterns recorded below 50 K. An unusual discontinuity in the unit-cell volume is seen around Tf, indicating a coupling of this second transition with the contraction of the lattice. Attempts to unravel this interesting magnetic behavior using ac susceptibility measurements led to the existence of glassy magnetism below Tf. Systematic analysis of the susceptibility results along with neutron depolarization measurement identifies the low-temperature phase as a reentrant cluster glass.

Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor

PubMed Central

Rusi; Chan, P. Y.; Majid, S. R.

2015-01-01

The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm-2. The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg-1 at current density of 1.85 Ag-1 in 0.5M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5M KOH and 0.5M KOH/0.04M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 103 Fg-1 and an energy density of 309 Whkg-1 in a 0.5MKOH/0.04MK3Fe(CN) 6 electrolyte at a current density of 10 Ag-1. The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications. PMID:26158447

Effect of Cryogenic Treatment on Microstructure and Mechanical Properties of 0Cr12Mn5Ni4Mo3Al Steel

NASA Astrophysics Data System (ADS)

Bai, Xue; Zheng, Linbin; Cui, Jinyan; Wu, Sujun; Song, Ruokang; Xie, Di; Wang, Dawei; Li, Haisheng

2017-10-01

This paper systematically investigated the effect of cryogenic temperature and soaking time on the 0Cr12Mn5Ni4Mo3Al steel. Microstructure observation and mechanical tests were performed on the specimens by scanning electron microscopy, x-ray diffraction, Vickers hardness tests and tensile tests. Cryogenic treatments were carried out at different temperatures of -73, -120, -160 and -196 °C for a given soaking time of 4 h and at a specific temperature of -73 °C for different soaking time of 8, 12, 21 and 32 h, followed by the subsequent tempering treatment. The results showed that the volume fraction of martensite in this steel has significantly increased and the size of martensite lath has decreased after cryogenic treatment, which leads to the improvement of the mechanical properties of the steel. The cryogenic treatment affected the microstructure by promoting the transformation of retained austenite to martensite and the formation of reversed austenite in the steel. The optimal hardness and strength of this steel were obtained by cryogenic treatment at -73 °C for 8 h. It has been found that the soaking time is a critical parameter for the mechanical properties of 0Cr12Mn5Ni4Mo3Al steel. When the cryogenic temperature is lower than -73 °C, there is no further improvement of the mechanical properties.

Genotoxicity assessment and oxidative stress responses in freshwater African catfish Clarias gariepinus exposed to fenthion formulations.

PubMed

Nwani, Christopher Didigwu; Somdare, Peace Onas; Ogueji, Emmanuel Okechukwu; Nwani, Jacinta Chinedu; Ukonze, Juliana Adimonye; Nwadinigwe, Alfreda O

2017-07-01

Fenthion is one of the most widely used organophosphate insecticides for the control of many varieties of pests in Nigeria. The genotoxic effect of the pesticide was evaluated in the blood erythrocytes of Clarias gariepinus using the micronucleus (MN) test. The oxidative stress parameters were also studied in the liver and gill tissues. Fish were exposed to 2.0, 4.0, and 8.0 mgL -1 of fenthion and sampling was done on days 1, 7, 14, 21 and after 7-day recovery. Micronuclei induction was highest (7.55) on day 14 at all concentrations in the peripheral blood cells. Oxidative stress was evidenced by increased lipid peroxidation (LPO). Maximum LPO values of 62.47% and 71.17% were observed in the gill and liver tissues respectively in C. gariepinus exposed to 8.0 mgL -1 concentration of fenthion. There were alterations in the values of reduced glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) during the exposure and recovery periods. The 7-day recovery period was not adequate to eliminate fenthion-induced changes as LPO, CAT, and GR activity remain elevated. However, MN frequency and activity of SOD, GSH, and GPx (except at 8.0 mgL -1 ) recovered. The present findings give further credence on the integrated use of MN test and oxidative stress parameters in risk assessment of pollutants in aquatic ecosystem.

Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor.

PubMed

Rusi; Chan, P Y; Majid, S R

2015-01-01

The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm(-2). The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg(-1) at current density of 1.85 Ag(-1) in 0.5 M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5 M KOH and 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 10(3) Fg(-1) and an energy density of 309 Whkg(-1) in a 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolyte at a current density of 10 Ag(-1). The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications.

Manganese Deficiency Leads to Genotype-Specific Changes in Fluorescence Induction Kinetics and State Transitions1[C][OA

PubMed Central

Husted, Søren; Laursen, Kristian H.; Hebbern, Christopher A.; Schmidt, Sidsel B.; Pedas, Pai; Haldrup, Anna; Jensen, Poul E.

2009-01-01

Barley (Hordeum vulgare) genotypes display a marked difference in their ability to tolerate growth at low manganese (Mn) concentrations, a phenomenon designated as differential Mn efficiency. Induction of Mn deficiency in two genotypes differing in Mn efficiency led to a decline in the quantum yield efficiency for both, although faster in the Mn-inefficient genotype. Leaf tissue and thylakoid Mn concentrations were reduced under Mn deficiency, but no difference between genotypes was observed and no visual Mn deficiency symptoms were developed. Analysis of the fluorescence induction kinetics revealed that in addition to the usual O-J-I-P steps, clear K and D steps were developed in the Mn-inefficient genotype under Mn deficiency. These marked changes indicated damages to photosystem II (PSII). This was further substantiated by state transition measurements, indicating that the ability of plants to redistribute excitation energy was reduced. The percentage change in state transitions for control plants with normal Mn supply of both genotypes was 9% to 11%. However, in Mn-deficient leaves of the Mn-inefficient genotypes, state transitions were reduced to less than 1%, whereas no change was observed for the Mn-efficient genotypes. Immunoblotting and the chlorophyll a/b ratio confirmed that Mn deficiency in general resulted in a significant reduction in abundance of PSII reaction centers relative to the peripheral antenna. In addition, PSII appeared to be significantly more affected by Mn limitation than PSI. However, the striking genotypic differences observed in Mn-deficient plants, when analyzing state transitions and fluorescence induction kinetics, could not be correlated with specific changes in photosystem proteins. Thus, there is no simple linkage between protein expression and the differential reduction in state transition and fluorescence induction kinetics observed for the genotypes under Mn deficiency. PMID:19369593

Structure and magnetic properties of L n MnSbO ( L n = La and Ce)

DOE PAGES

Zhang, Qiang; Kumar, C. M. N.; Tian, Wei; ...

2016-03-11

Here, a neutron powder diffraction (NPD) study of LnMnSbO (Ln = La or Ce) reveals differences between the magnetic ground state of the two compounds due to the strong Ce-Mn coupling compared to La-Mn. The two compounds adopt the P4/nmm space group down to 2 K, and whereas magnetization measurements do not show obvious anomaly at high temperatures, NPD reveals a C-type antiferromagnetic (AFM) order below T N = 255K for LaMnSbO and 240 K for CeMnSbO. While the magnetic structure of LaMnSbO is preserved to base temperature, a sharp transition at T SR = 4.5K is observed in CeMnSbOmore » due to a spin-reorientation (SR) transition of the Mn 2+ magnetic moments from pointing along the c axis to the ab plane. The SR transition in CeMnSbO is accompanied by a simultaneous long-range AFM ordering of the Ce moments, which indicates that the Mn SR transition is driven by the Ce-Mn coupling. The ordered moments are found to be somewhat smaller than those expected for Mn 2+ (S = 5/2) in insulators, but large enough to suggest that these compounds belong to the class of local-moment antiferromagnets. The lower T N found in these two compounds compared to the As-based counterparts (T N = 317 for LaMnAsO, T N = 347K for CeMnAsO) indicates that the Mn-Pn (Pn=As or Sb) hybridization that mediates the superexchange Mn-Pn-Mn coupling is weaker for the Sb-based compounds.« less

Synthesis, characterization and electrochemical performance of Al-substituted Li₂MnO₃

DOE PAGES

Dhital, Chetan; Huq, Ashfia; Paranthaman, Mariappan Parans; ...

2015-08-08

Li 2MnO 3 is known to be electrochemically inactive due to Mn in tetravalent oxidation state. Several compositions such as Li 2MnO 3 , Li 1.5Al 0.17MnO 3, Li 1.0Al 0.33MnO 3 and Li 0.5Al 0.5MnO 3 were synthesized by a sol–gel Pechini method. All the samples were characterized with x-ray diffraction, Raman, x-ray photoelectron spectroscopy, scanning electron microscopy, Tap density and BET analyzer. X-ray diffraction patterns indicated the presence of monoclinic phase for pristine Li 2MnO 3and mixed monoclinic/spinel phases (Li 2 - xMn 1 - yAl x + yO 3 + z) for Al-substituted Li 2MnO 3compounds. Themore » Al substitution seems to occur both at Li and Mn sites, which could explain the presence of spinel phase. X-ray photoelectron spectroscopy for Mn 2p orbital reveals a significant decrease in binding energy for Li 1.0Al 0.33MnO 3 and Li 0.5Al 0.5MnO 3 compounds. Cyclic voltammetry, charge/discharge cycles and electrochemical impedance spectroscopy were also performed. A discharge capacity of 24 mAh g -1 for Li 2MnO 3, 68 mAh g -1 for Li 1.5Al 0.17MnO 3, 58 mAh g -1 for Li 1.0Al 0.33MnO 3 and 74 mAh g -1 for Li 0.5Al 0.5MnO 3 were obtained. As a result, aluminum substitutions increased the formation of spinel phase which is responsible for cycling.« less

Leaf cDNA-AFLP analysis of two citrus species differing in manganese tolerance in response to long-term manganese-toxicity

PubMed Central

2013-01-01

Background Very little is known about manganese (Mn)-toxicity-responsive genes in citrus plants. Seedlings of ‘Xuegan’ (Citrus sinensis) and ‘Sour pummelo’ (Citrus grandis) were irrigated for 17 weeks with nutrient solution containing 2 μM (control) or 600 μM (Mn-toxicity) MnSO4. The objectives of this study were to understand the mechanisms of citrus Mn-tolerance and to identify differentially expressed genes, which might be involved in Mn-tolerance. Results Under Mn-toxicity, the majority of Mn in seedlings was retained in the roots; C. sinensis seedlings accumulated more Mn in roots and less Mn in shoots (leaves) than C. grandis ones and Mn concentration was lower in Mn-toxicity C. sinensis leaves compared to Mn-toxicity C. grandis ones. Mn-toxicity affected C. grandis seedling growth, leaf CO2 assimilation, total soluble concentration, phosphorus (P) and magenisum (Mg) more than C. sinensis. Using cDNA-AFLP, we isolated 42 up-regulated and 80 down-regulated genes in Mn-toxicity C. grandis leaves. They were grouped into the following functional categories: biological regulation and signal transduction, carbohydrate and energy metabolism, nucleic acid metabolism, protein metabolism, lipid metabolism, cell wall metabolism, stress responses and cell transport. However, only 7 up-regulated and 8 down-regulated genes were identified in Mn-toxicity C. sinensis ones. The responses of C. grandis leaves to Mn-toxicity might include following several aspects: (1) accelerating leaf senescence; (2) activating the metabolic pathway related to ATPase synthesis and reducing power production; (3) decreasing cell transport; (4) inhibiting protein and nucleic acid metabolisms; (5) impairing the formation of cell wall; and (6) triggering multiple signal transduction pathways. We also identified many new Mn-toxicity-responsive genes involved in biological and signal transduction, carbohydrate and protein metabolisms, stress responses and cell transport. Conclusions Our results demonstrated that C. sinensis was more tolerant to Mn-toxicity than C. grandis, and that Mn-toxicity affected gene expression far less in C. sinensis leaves. This might be associated with more Mn accumulation in roots and less Mn accumulation in leaves of Mn-toxicity C. sinensis seedlings than those of C. grandis seedlings. Our findings increase our understanding of the molecular mechanisms involved in the responses of plants to Mn-toxicity. PMID:24034812

Manganese Fractionation Using a Sequential Extraction Method to Evaluate Welders' Shielded Metal Arc Welding Exposures During Construction Projects in Oil Refineries.

PubMed

Hanley, Kevin W; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin

2015-01-01

The National Institute for Occupational Safety and Health has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013-29 for soluble Mn in a mild ammonium acetate solution; from 0.26-250 for Mn(0,2+) in acetic acid; from non-detectable (ND) - 350 for Mn(3+,4+) in hydroxylamine-hydrochloride; and from ND - 39 micrograms per cubic meter (μg/m(3)) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52-470 μg/m(3). The range of respirable particulate Mn TWA concentrations were from 0.20-28 for soluble Mn; from 1.4-270 for Mn(0,2+); from 0.49-150 for Mn(3+,4+); from ND - 100 for insoluble Mn; and from 2.0-490 μg/m(3) for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD = 3.35) and 8.7 (GSD = 3.54) μg/m(3) for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn(0,2+) fraction was the most abundant followed by Mn(3+,4+) fraction, typically >50% and ∼30-40% of Mn(sum), respectively. Eighteen welders' exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m(3)) and 25 exceeded the recently adopted respirable Mn TLV (20 μg/m(3)). This study shows that a welding fume exposure control and management program is warranted, especially for welding jobs in confined spaces.

Manganese fractionation using a sequential extraction method to evaluate welders’ shielded metal arc welding exposures during construction projects in oil refineries

PubMed Central

Hanley, Kevin W.; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin

2015-01-01

The National Institute for Occupational Safety and Health (NIOSH) has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013 – 29 for soluble Mn in a mild ammonium acetate solution; from 0.26 – 250 for Mn0,2+ in acetic acid; from non-detectable (ND) – 350 for Mn3+,4+ in hydroxylamine-hydrochloride; and from ND – 39 micrograms per cubic meter (μg/m3) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52 to 470 μg/m3. The range of respirable particulate Mn TWA concentrations were from 0.20 – 28 for soluble Mn; from 1.4 – 270 for Mn0,2+; from 0.49 – 150 for Mn3+,4+; from ND – 100 for insoluble Mn; and from 2.0 – 490 μg/m3 for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD=3.35) and 8.7 (GSD=3.54) μg/m3 for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn0,2+ fraction was the most abundant followed by Mn3+,4+ fraction, typically >50% and ~30-40% of Mn(sum), respectively. Eighteen welders’ exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m3) and 25 exceeded the recently adopted respirable Mn TLV (20 μg/m3). This study shows that a welding fume exposure control and management program is warranted, especially for welding jobs in confined spaces. PMID:26011602

Crystal growth and crystal structures of six novel phases in the Mn/As/O/Cl(Br) system, as well as magnetic properties of α-Mn3(AsO4)2

NASA Astrophysics Data System (ADS)

Weil, Matthias; Kremer, Reinhard K.

2017-01-01

Chemical vapour transport reactions (900 °C → 820 °C, Cl2 or Br2 as transport agent) of in situ formed Mn3(AsO4)2 yielded the orthoarsenates(V) α-Mn3(AsO4)2 and β-Mn3(AsO4)2 as well as the oxoarsenate(V) halide compounds Mn7(AsO4)4Cl2, Mn11(AsO4)7Cl, Mn11(AsO4)7Br and Mn5(AsO4)3Cl. The crystal structures of all six phases were determined from single crystal X-ray diffraction data. The crystal structures of α-and β-Mn3(AsO4)2 are isotypic with the corresponding phosphate phases γ- and α-Mn3(PO4)2, respectively, and are reported here for the first time. A comparative discussion with other structures of general composition M3(AsO4)2 (M = Mg; divalent first-row transition metal) is given. The unique crystal structures of Mn7(AsO4)4Cl2 and that of the two isotypic Mn11(AsO4)7X (X = Cl, Br) structures are composed of two [MnO5] polyhedra, two [MnO4Cl2] polyhedra (one with site symmetry 1 bar), two AsO4 tetrahedra, and one [MnO5] polyhedron, three [MnO6] octahedra (one with site symmetry.m.), one [MnO4X], one [MnO5X] polyhedron and four AsO4 tetrahedra, respectively. The various polyhedra of the three arsenate(V) halides are condensed into three-dimensional framework structures by corner- and edge-sharing. Mn5(AsO4)3Cl adopts the chloroapatite structure. The magnetic and thermal properties of pure polycrystalline samples of a-Mn3(AsO4)2 were investigated in more detail. The magnetic susceptibility proves all Mn atoms to be in the oxidation state +2 yielding an effective magnetic moment per Mn atom of 5.9 μB. Long-range antiferromagnetic ordering is observed below 8.2 K consistent with the negative Curie-Weiss temperature of -50 K derived from the high temperature susceptibility data.

The Ti-Mn system revisited: experimental investigation and thermodynamic modelling.

PubMed

Khan, A U; Brož, P; Premović, M; Pavlů, J; Vřeštál, J; Yan, X; Maccio, D; Saccone, A; Giester, G; Rogl, P

2016-08-17

As the Ti-Mn phase diagram is part of numerous ternary and higher order systems of technological importance, the present paper defines phase relations which have been experimentally established throughout this work from 800 °C to the melting range based on Differential Thermal Analyses (DTA), X-ray powder diffraction, metallography and Electron Probe Micro Analysis (EPMA) techniques on ∼50 alloys, which were prepared by arc melting or high frequency melting under high purity argon starting from freshly cleaned metal ingots. Novel compounds were identified and reaction isotherms were redefined accordingly. In the Ti-rich region a novel compound TiMn was detected, sandwiched between the known phases: TiMn1-x (∼45 at% Mn) and TiMn1+x (∼55 at% Mn). In the Mn-rich region the hitherto unknown crystal structure of TiMn∼3 was solved from X-ray single crystal diffraction data and found to be of a unique structure type Ti6(Ti1-xMnx)6Mn25 (x = 0.462; space group Pbam (#55); a = 0.79081(3) nm, b = 2.58557(9) nm, c = 0.47931(2) nm), which consists of two consecutive layers of the hexagonal MgZn2-type Laves phase (TiMn2) and a combined layer of alternate structure blocks of MgZn2 type and Zr4Al3 type. Whereas TiMn can be considered as a line compound (solubility range <∼1 at%), the homogeneity regions of the Ti-Mn compounds are significant (determined by EPMA): TiMn1-x (44.0 to 46.6 at% Mn), TiMn1+x (54.6 to 56.3 at% Mn), Ti1+xMn2-x (MgZn2-type, 59 to 69 at% Mn at 1000 °C: -0.08 < x < 0.23), TiMn∼3 (unique type; 74 to 76.5 at% Mn) and TiMn∼4 (R-phase: Ti8(TixMn1-x)6Mn39, 80 to 84 at% Ti). Supported by ab initio calculations of the ground state energy for the Laves phase, the new experimental results enabled thermodynamic modelling of the entire Ti-Mn phase diagram providing a complete and novel set of thermodynamic data thus providing a sound basis for future thermodynamic predictions of higher order Ti-Mn-X-Y systems.

31. Photocopy of line illustration; originally published in William N. ...

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

31. Photocopy of line illustration; originally published in William N. Carey, 'St. Paul Builds an Airport One Mile From Post Office,' Engineering News-Record, (August 21, 1930), figure 6, page 294; SHOWS CANTILEVERED ROOF-TRUSS SYSTEM OF MUNICIPAL HANGAR COMPLETED AT ST. PAUL MUNICIPAL AIRPORT IN 1930; THE STRUCTURAL DESIGN WAS BASED ON THAT OF THE NORTHWEST AIRWAYS HANGAR, EXCEPT FOR THE SUBSTITUTION OF BOWSTRING TRUSSES FOR TRAPEZOIDAL TRUSSES - Northwest Airways Hangar & Administration Building, 590 Bayfield Street, St. Paul Downtown Airport (Holman), Saint Paul, Ramsey County, MN

Thermoregulatory, Behavioral, and Metabolic Responses to Heatstroke in a Conscious Mouse Model

DTIC Science & Technology

2010-04-28

important for survival. Delayed hyperthermia has been observed in HS patients during the hours, days, and weeks of recovery (21). The occurrence of ...radiotelemetry transmitter device (Model TA10TA-F20; Data Sciences International, St. Paul, MN) for remote sensing of Tc ( 0.1°C). The transmitter weighed 3.6...intervals by high-speed gas sensing O2 and CO2 analyzers (0.002%). V̇O2 and V̇CO2 values were normalized to body weight0.75, although mice of similar

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

PubMed Central

Geitenbeek, Robin G.; Meijerink, Andries

2017-01-01

Mn4+-activated hexafluoroaluminates are promising red-emitting phosphors for white light emitting diodes (w-LEDs). Here, we report the synthesis of Na3AlF6:Mn4+, K3AlF6:Mn4+ and K2NaAlF6:Mn4+ phosphors through a simple two-step co-precipitation method. Highly monodisperse large (~20 μm) smoothed-octahedron shaped crystallites are obtained for K2NaAlF6:Mn4+. The large size, regular shape and small size distribution are favorable for application in w-LEDs. All Mn4+-doped hexafluoroaluminates show bright red Mn4+ luminescence under blue light excitation. We compare the optical properties of Na3AlF6:Mn4+, K3AlF6:Mn4+ and K2NaAlF6:Mn4+ at room temperature and 4 K. The luminescence measurements reveal that multiple Mn4+ sites exist in M3AlF6:Mn4+ (M = Na, K), which is explained by the charge compensation that is required for Mn4+ on Al3+ sites. Thermal cycling experiments show that the site distribution changes after annealing. Finally, we investigate thermal quenching and show that the luminescence quenching temperature is high, around 460–490 K, which makes these Mn4+-doped hexafluoroaluminates interesting red phosphors for w-LEDs. The new insights reported on the synthesis and optical properties of Mn4+ in the chemically and thermally stable hexafluoroaluminates can contribute to the optimization of red-emitting Mn4+ phosphors for w-LEDs. PMID:29149083

Manganese soil and foliar fertilization of olive plantlets: the effect on leaf mineral and phenolic content and root mycorrhizal colonization.

PubMed

Pasković, Igor; Ćustić, Mirjana Herak; Pecina, Marija; Bronić, Josip; Ban, Dean; Radić, Tomislav; Pošćić, Filip; Jukić Špika, Maja; Soldo, Barbara; Palčić, Igor; Goreta Ban, Smiljana

2018-06-08

The aim of this study was to examine the effect of foliar (Mn_fol) and soil Zeolite-Mn (Mn_ZA) application on leaf mineral, total phenolic and oleuropein content, and mycorrhizae colonization of self-rooted cv. Leccino plantlets grown on calcareous soil. The dissolution of zeolite was 97% when citric acid was applied at 0.05 mM dm -3 , suggesting that organic acids excreted by roots can dissolve modified zeolite (Mn_ZA) making Mn available for plant uptake. The leaf Mn concentration was the highest for Mn_fol treatment at 90 DAT (172 mg kg -1 ) and 150 DAT (70 mg kg -1 ) compared to other treatments. Mn_ZA soil application increased leaf Mn concentration at 150 DAT compared to control and NPK treatment. The oleuropein leaf content was highest for Mn_fol compared to other treatments at 90 DAT and lowest at 150 DAT. Arbuscular mycorrhizal colonization was higher for Mn_fol treatment at 150 DAT compared to all other treatments. Changes in the arbuscular colonization percentage and oleuropein content may be connected to stress conditions provoked by high leaf Mn concentration in Mn_fol treatment at 90 DAT. Mn_ZA application increased leaf Mn concentration at 150 DAT compared to control and NPK treatments. It can be assumed that the dominant mechanism in Mn uptake from modified zeolite is Mn_ZA dissolution through root exudates. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Nucleation/Growth Mechanisms and Morphological Evolution of Porous MnO2 Coating Deposited on Graphite for Supercapacitor

PubMed Central

Huang, Wenxin; Xu, Yunhe

2017-01-01

The nucleation and growth mechanisms of porous MnO2 coating deposited on graphite in MnSO4 solution were investigated in detail by cyclic voltammetry, chronoamperometry and scanning electron microscopy. The electrochemical properties of honeycomb-like MnO2 were evaluated by cycle voltammetry and galvanostatic charge-discharge. Results indicated that MnO2 was synthesized by the following steps: Mn2+→Mn3++e−, Mn3++2H2O→MnOOH+3H+, and MnOOH→MnO2+H++e−. The deposition of MnO2 was divided into four stages. A short incubation period (approximately 1.5 s) was observed, prior to nucleation. The decreasing trend of the current slowed as time increased due to nucleation and MnO2 growth in the second stage. A huge number of nuclei were formed by instantaneous nucleation, and these nuclei grew and connected with one another at an exceedingly short time (0.5 s). In the third stage, the gaps in-between initial graphite flakes were filled with MnO2 until the morphology of the flakes gradually became similar to that of the MnO2-deposited layer. In the fourth stage, the graphite electrode was covered completely with a thick and dense layer of MnO2 deposits. All MnO2 electrodes at different deposition times obtained nearly the same specific capacitance of approximately 186 F/g, thus indicating that the specific capacitance of the electrodes is not related with deposition time. PMID:29048377

Growth mode and structures of magnetic Mn clusters on graphene

DOE PAGES

Liu, Xiaojie; Wang, Cai-Zhuang

2016-06-22

We present a systematic study of Mn clusters on graphene by first-principles calculations. We show that the growth of Mn on graphene follows a three-dimensional (3D) mode. Both adsorption and attachment energies show that (Mn) 3 and (Mn) 6 on graphene are energetically favorable in the size range (Mn) 1-7. Moreover, larger formation energy for Mn cluster on graphene implies the incoming Mn atoms are likely to nucleate and grow into bigger and bigger Mn clusters on graphene. The magnetic moments of (Mn) 1,5,7 on graphene are enhanced by 11%, 186%, and 26% from their values at free-standing clusters, respectively.more » By contrast, the net magnetic moment of (Mn) 2,3,4,6 on graphene is reduced from that of the corresponding free-standing clusters. The origin of the magnetic moment changes can be attributed to the charge transfer within the Mn clusters and between the clusters and graphene upon adsorption.« less

Biological Low-pH Mn(II) Oxidation in a Manganese Deposit Influenced by Metal-Rich Groundwater

PubMed Central

Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.

2016-01-01

ABSTRACT The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems. IMPORTANCE This study provides multiple lines of evidence to show that microbes are the main drivers of Mn(II) oxidation even at acidic pH, offering new insights into Mn biogeochemical cycling. A distinct, highly adapted microbial community inhabits acidic, oligotrophic Mn deposits and mediates biological Mn oxidation. These data highlight the importance of biological processes for Mn biogeochemical cycling and show the potential for new bioremediation strategies aimed at enhancing biological Mn oxidation in low-pH environments for contaminant mitigation. PMID:26969702

Enhanced electrochemical performance of LiMn2O4 by constructing a stable Mn2+-rich interface

NASA Astrophysics Data System (ADS)

Lu, Zhongpei; Lu, Xiaojun; Ding, Jingjing; Zhou, Ting; Ge, Tao; Yang, Gang; Yin, Fan; Wu, Mingfang

2017-12-01

Spinel LiMn2O4 has drawn continuous attentions due to its low cost, good electrochemical performance, environmental friendliness and natural abundant resources. In view of its severe capacity fading, some types of manganese-based compounds with different Mn oxidation states are selected to protect bare LiMn2O4 by constructing a stable coating layer. In this work, LiMn2O4@LiMnPO4 composite, spherical LiMn2O4 (LMO) as core and Mn2+-rich phase of LiMnPO4 (LMP) as shell, is designed and synthesized. Two composites of LiMn2O4 particles coated with 3 wt% and 10 wt% LiMnPO4 have been compared studied. After 100 cycles at 0.5C rate, the two samples deliver capacity retentions of 96.63% and 93.23% of their initial capacities. Moreover, LMO coated by 3 wt% LiMnPO4 delivers 100.3 mAh g-1 after 200 cycles at 10C rate and 76.3 mAh g-1 after 1000 cycles at 20C rate, much higher than bare LiMn2O4 with 90 mAh g-1 and 45.8 mAh g-1, respectively. This core-shell structure with Mn2+-rich phase as a coating layer effectively enhance the material's cycling performance and rate capacity by reducing the contact of LiMn2O4 with electrolyte.

A new mineral species rossovskyite, (Fe3+,Ta)(Nb,Ti)O4: crystal chemistry and physical properties

NASA Astrophysics Data System (ADS)

Konovalenko, Sergey I.; Ananyev, Sergey A.; Chukanov, Nikita V.; Rastsvetaeva, Ramiza K.; Aksenov, Sergey M.; Baeva, Anna A.; Gainov, Ramil R.; Vagizov, Farit G.; Lopatin, Oleg N.; Nebera, Tatiana S.

2015-11-01

A new mineral rossovskyite named after L.N. Rossovsky was discovered in granite pegmatites of the Bulgut occurrence, Altai Mts., Western Mongolia. Associated minerals are microcline, muscovite, quartz, albite, garnet of the almandine-spessartine series, beryl, apatite, triplite, zircon, pyrite, yttrobetafite-(Y) and schorl. Rossovskyite forms flattened anhedral grains up to 6 × 6 × 2 cm. The color of the mineral is black, and the streak is black as well. The luster is semi-metallic, dull. Mohs hardness is 6. No cleavage or parting is observed. Rossovskyite is brittle, with uneven fracture. The density measured by the hydrostatic weighing method is 6.06 g/cm2, and the density calculated from the empirical formula is 6.302 g/cm3. Rossovskyite is biaxial, and the color in reflection is gray to dark gray. The IR spectrum contains strong band at 567 cm-1 (with shoulders at 500 and 600 cm-1) corresponding to cation-oxygen stretching vibrations and weak bands at 1093 and 1185 cm-1 assigned as overtones. The reflection spectrum in visible range is obtained. According to the Mössbauer spectrum, the ratio Fe2+:Fe3+ is 35.6:64.4. The chemical composition is as follows (electron microprobe, Fe apportioned between FeO and Fe2O3 based on Mössbauer data, wt%): MnO 1.68, FeO 5.92, Fe2O3 14.66, TiO2 7.69, Nb2O5 26.59, Ta2O5 37.51, WO3 5.61, total 99.66. The empirical formula calculated on four O atoms is: {{Mn}}_{0.06}^{2 + } {{Fe}}_{0.21}^{2 + } {{Fe}}_{0.47}^{3 + } Ti0.25Nb0.51Ta0.43W0.06O4. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is monoclinic, space group P2/ c, a = 4.668(1), b = 5.659(1), c = 5.061(1) Å, β = 90.21(1)º; V = 133.70(4) Å3, Z = 2. Topologically, the structure of rossovskyite is analogous to that of wolframite-group minerals. The crystal-chemical formula of rossovskyite is [(Fe3+, Fe2+, Mn)0.57Ta0.32Nb0.11][Nb0.40Ti0.25Fe0.18Ta0.11W0.06]O4. The strongest lines of the powder X-ray diffraction pattern [ d, Å (I, %) ( hkl)] are as follows: 3.604 (49) (110), 2.938 (100) (-1-11), 2.534 (23) (002), 2.476 (29) (021), 2.337 (27) (200), 1.718 (26) (-202), 1.698 (31) (-2-21), 1.440 (21) (-311). The type specimen of rossovskyite is deposited in the Mineralogical Museum of the Tomsk State University, Tomsk, 634050 Russia, with the inventory number 20927.

Highly atom-economic synthesis of graphene/Mn3O4 hybrid composites for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Jiangying, Qu; Feng, Gao; Quan, Zhou; Zhiyu, Wang; Han, Hu; Beibei, Li; Wubo, Wan; Xuzhen, Wang; Jieshan, Qiu

2013-03-01

A highly atom-economic procedure for the preparation of reduced graphene oxide/Mn3O4 (rGO/Mn3O4) composites is reported. Pristine graphene oxide/manganese sulfate (GO/MnSO4) suspension produced by modified Hummers method is utilized with high efficiency, which has been in situ converted into GO/Mn3O4 hybrid composite by air oxidation, then into rGO/Mn3O4 composite by means of dielectric barrier discharge (DBD) plasma-assisted deoxygenation. The Mn3O4 content of the rGO/Mn3O4 composites can be readily tailored. It is observed that Mn3O4 nanoparticles of 15-24 nm are well-dispersed on graphene sheets with Mn3O4 loading as high as 90%. The specific capacitance of the as-prepared rGO/Mn3O4 hybrids with 90% Mn3O4 reaches 193 F g-1 when employed as the electrode material in neutral Na2SO4 electrolyte solutions (76 F g-1 for pristine graphene and 95 F g-1 for pure Mn3O4), which indicates the positive synergetic effects from both graphene and attached Mn3O4. The method developed in this study should offer a new technique for the large scale and highly atom-economic production of graphene/MnOx composites for many applications.

Determination of the Mg/Mn ratio in foraminiferal coatings: An approach to correct Mg/Ca temperatures for Mn-rich contaminant phases

NASA Astrophysics Data System (ADS)

Hasenfratz, Adam P.; Martínez-García, Alfredo; Jaccard, Samuel L.; Vance, Derek; Wälle, Markus; Greaves, Mervyn; Haug, Gerald H.

2017-01-01

The occurrence of manganese-rich coatings on foraminifera can have a significant effect on their bulk Mg/Ca ratios thereby biasing seawater temperature reconstructions. The removal of this Mn phase requires a reductive cleaning step, but this has been suggested to preferentially dissolve Mg-rich biogenic carbonate, potentially introducing an analytical bias in paleotemperature estimates. In this study, the geochemical composition of foraminifera tests from Mn-rich sediments from the Antarctic Southern Ocean (ODP Site 1094) was investigated using solution-based and laser ablation ICP-MS in order to determine the amount of Mg incorporated into the coatings. The analysis of planktonic and benthic foraminifera revealed a nearly constant Mg/Mn ratio in the Mn coating of ∼0.2 mol/mol. Consequently, the coating Mg/Mn ratio can be used to correct for the Mg incorporated into the Mn phase by using the down core Mn/Ca values of samples that have not been reductively cleaned. The consistency of the coating Mg/Mn ratio obtained in this study, as well as that found in samples from the Panama Basin, suggests that spatial variation of Mg/Mn in foraminiferal Mn overgrowths may be smaller than expected from Mn nodules and Mn-Ca carbonates. However, a site-specific assessment of the Mg/Mn ratio in foraminiferal coatings is recommended to improve the accuracy of the correction.

Quantum chemical study of arsenic (III, V) adsorption on Mn-oxides: implications for arsenic(III) oxidation.

PubMed

Zhu, Mengqiang; Paul, Kristian W; Kubicki, James D; Sparks, Donald L

2009-09-01

Density functional theory (DFT) calculations were used to investigate As(V) and As(III) surface complex structures and reaction energies on both Mn(III) and Mn(IV) sites in an attempt to better understand As(III) oxidation bybirnessite, a layered Mn-dioxide mineral. Edge-sharing dioctahedral Mn(III) and Mn(IV) clusters with different combinations of surface functional groups (>MnOH and >MnOH2) were employed to mimic pH variability. Results show that As(V) adsorption was more thermodynamically favorable than As(III) adsorption on both Mn(III) and Mn(IV) surface sites under simulated acidic pH conditions. Therefore, we propose that As(V) adsorption inhibits As(III) oxidation by blocking adsorption sites. Under simulated acidic pH conditions, Mn(IV) sites exhibited stronger adsorption affinity than Mn(III) sites for both As(III) and As(V). Overall, we hypothesize that Mn(III) sites are less reactive in terms of As(III) oxidation due to their lower affinity for As(III) adsorption, higher potential to be blocked by As(V) complexes, and slower electron transfer rates with adsorbed As(III). Results from this study offer an explanation regarding the experimental observations of Mn(III) accumulation on birnessite and the long residence time of As(III) adsorption complexes on manganite (r-MnOOH) during As(III) oxidation.

Production of biogenic manganese oxides coupled with methane oxidation in a bioreactor for removing metals from wastewater.

PubMed

Matsushita, Shuji; Komizo, Daisuke; Cao, Linh Thi Thuy; Aoi, Yoshiteru; Kindaichi, Tomonori; Ozaki, Noriatsu; Imachi, Hiroyuki; Ohashi, Akiyoshi

2018-03-01

Biogenic manganese oxide (BioMnO x ) can efficiently adsorb various minor metals. The production of BioMnO x in reactors to remove metals during wastewater treatment processes is a promising biotechnological method. However, it is difficult to preferentially enrich manganese-oxidizing bacteria (MnOB) to produce BioMnO x during wastewater treatment processes. A unique method of cultivating MnOB using methane-oxidizing bacteria (MOB) to produce soluble microbial products is proposed here. MnOB were successfully enriched in a methane-fed reactor containing MOB. BioMnO x production during the wastewater treatment process was confirmed. Long-term continual operation of the reactor allowed simultaneous removal of Mn(II), Co(II), and Ni(II). The Co(II)/Mn(II) and Ni(II)/Mn(II) removal ratios were 53% and 19%, respectively. The degree to which Mn(II) was removed indicated that the enriched MnOB used utilization-associated products and/or biomass-associated products. Microbial community analysis revealed that methanol-oxidizing bacteria belonging to the Hyphomicrobiaceae family played important roles in the oxidation of Mn(II) by using utilization-associated products. Methane-oxidizing bacteria were found to be inhibited by MnO 2 , but the maximum Mn(II) removal rate was 0.49 kg m -3  d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Latent manganese deficiency increases transpiration in barley (Hordeum vulgare).

PubMed

Hebbern, Christopher A; Laursen, Kristian Holst; Ladegaard, Anne H; Schmidt, Sidsel B; Pedas, Pai; Bruhn, Dan; Schjoerring, Jan K; Wulfsohn, Dvoralai; Husted, Søren

2009-03-01

To investigate if latent manganese (Mn) deficiency leads to increased transpiration, barley plants were grown for 10 weeks in hydroponics with daily additions of Mn in the low nM range. The Mn-starved plants did not exhibit visual leaf symptoms of Mn deficiency, but Chl a fluorescence measurements revealed that the quantum yield efficiency of PSII (F(v)/F(m)) was reduced from 0.83 in Mn-sufficient control plants to below 0.5 in Mn-starved plants. Leaf Mn concentrations declined from 30 to 7 microg Mn g(-1) dry weight in control and Mn-starved plants, respectively. Mn-starved plants had up to four-fold higher transpiration than control plants. Stomatal closure and opening upon light/dark transitions took place at the same rate in both Mn treatments, but the nocturnal leaf conductance for water vapour was still twice as high in Mn-starved plants compared with the control. The observed increase in transpiration was substantiated by (13)C-isotope discrimination analysis and gravimetric measurement of the water consumption, showing significantly lower water use efficiency in Mn-starved plants. The extractable wax content of leaves of Mn-starved plants was approximately 40% lower than that in control plants, and it is concluded that the increased leaf conductance and higher transpirational water loss are correlated with a reduction in the epicuticular wax layer under Mn deficiency.

Bioefficacy comparison of organic manganese with inorganic manganese for eggshell quality in Hy-Line Brown laying hens.

PubMed

Xiao, J F; Wu, S G; Zhang, H J; Yue, H Y; Wang, J; Ji, F; Qi, G H

2015-08-01

This study was aimed at investigating the bioefficacy of organic compared with inorganic manganese (Mn) for eggshell quality. An amino acid-Mn complex or Mn sulfate monohydrate was used as the organic or inorganic Mn source. A total of six hundred forty-eight 50-wk-old layers (Hy-Line Brown) were divided into 9 groups; each group consisted of 6 replicates with 12 layers each. The feeding trial lasted 12 wk. During the first 4 wk of the feeding trial, the groups were fed a basal diet, which met the nutrient requirements of the layers, except for Mn. During the following 8 wk, 9 levels of Mn (inorganic Mn: 0, 25, 50, 100, and 200 mg/kg; organic Mn: 25, 50, 100, and 200 mg/kg) were used to supplement, respectively, in the basal diet on an equimolar basis. An exponential regression model was applied to calculate the bioefficacy of organic Mn compared with the inorganic Mn. Dietary supplementation with either organic or inorganic Mn did not influence egg production and feed efficiency of (P > 0.05), and eggshell quality did not exhibit a significant response to dietary supplementation with Mn sources at 56 and 58 wk (P > 0.05). Dietary supplementation with either organic Mn or inorganic Mn significantly enhanced the thickness, breaking strength, and elastic modulus of the eggshells compared with the control group at the end of 62 wk (P < 0.05). At the end of 62 wk, the bioefficacy of organic Mn was 357% (shell thickness), 406% (breaking strength), 458% (elastic modulus), and 470% (eggshell Mn), as efficacious as inorganic Mn at equimolar levels. This study suggests that organic Mn enhances eggshell quality in aged laying hens compared with inorganic Mn. © 2015 Poultry Science Association Inc.

Secretome-based Manganese(II) Oxidation by Filamentous Ascomycete Fungi

NASA Astrophysics Data System (ADS)

Zeiner, C. A.; Purvine, S.; Zink, E.; Paša-Tolić, L.; Chaput, D.; Wu, S.; Santelli, C. M.; Hansel, C. M.

2017-12-01

Manganese (Mn) oxides are among the strongest oxidants in the environment, and Mn(II) oxidation to Mn(III/IV) (hydr)oxides includes both abiotic and microbially-mediated processes. While white-rot Basidiomycete fungi oxidize Mn(II) using laccases and Mn peroxidases in association with lignocellulose degradation, the mechanisms by which filamentous Ascomycete fungi oxidize Mn(II) and a physiological role for Mn(II) oxidation in these organisms remain poorly understood. Through a combination of chemical and in-gel assays, bulk mass spectrometry, and iTRAQ proteomics, we demonstrate enzymatic Mn(II) oxidation in the secretomes of three phylogenetically diverse Ascomycetes that were isolated from Mn-laden sediments. Candidate Mn(II)-oxidizing enzymes were species-specific and included bilirubin oxidase and tyrosinase in Stagonospora sp. SRC1lsM3a, GMC oxidoreductase in Paraconiothyrium sporulosum AP3s5-JAC2a, and FAD-binding oxidoreductases in Pyrenochaeta sp. DS3sAY3a. These findings were supported by full proteomic characterization of the secretomes, which revealed a lack of Mn, lignin, and versatile peroxidases in these Ascomycetes but a substantially higher proportion of LMCOs and GMC oxidoreductases compared to wood-rot Basidiomycetes. We also identified the potential for indirect enzymatic Mn(II) oxidation by hydroxyl radical, as the secretomes were rich in diverse lignocellulose-degrading enzymes that could participate in Fenton chemistry. A link between Mn(II) oxidation and carbon oxidation analogous to white-rot Basidiomycetes remains unknown in these Ascomycetes. Interestingly, growth rates on rich medium were unaffected by the presence of Mn(II), and the production of Mn(II)-oxidizing proteins in the secretome was constitutive and not inducible by Mn(II). Thus, no physiological benefit of Mn(II) oxidation in these Ascomycetes has yet been identified, and Mn(II) oxidation appears to be a side reaction. Future work will explore the lignin-degrading capacity of these fungi and any associated role of Mn(II) oxidation.

Novel phosphate halides BaMn{sup III}[PO{sub 4}]FCl and BaMn{sup III}[PO{sub 4}]F{sub 2}: Effects of mixed halides on crystal structures and magnetic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pei, Da-Ting, E-mail: pdtcug@gmail.com; Sun, Wei, E-mail: 421221789@qq.com; Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Canada SK S7N 5E2

2016-02-15

Two new phosphate halides BaMn{sup III}[PO{sub 4}]FCl (1) and BaMn{sup III}[PO{sub 4}]F{sub 2} (2), have been synthesized under hydrothermal conditions. Structural characterizations show that both new compounds adopt layered structures but with different polyhedral linkages. Introduction of Cl into Compound (1) results in isolated hemimorphic [MnO{sub 4}FCl] octahedra, different from the chain of [MnO{sub 4}F{sub 2}]/[MnO{sub 2}F{sub 4}] octahedra in Compound (2). These compounds have significantly different molecular vibration modes and thermal stabilities. Magnetic measurements reveal that Compound (2) has larger antiferromagnetic interactions than Compound (1), because the former has strong interactions between Mn{sup 3+}-Mn{sup 3+} ions within corner-shared Mn{supmore » 3+}-octahedral chains whereas the latter only possesses isolated Mn{sup 3+}-octahedra. Both compounds transform to a new orthorhombic compound BaMn{sup II}(PO{sub 4})F (3) after thermal decomposition. - Graphical abstract: The large radius of Cl{sup -} ions makesBaMn{sup III}[PO{sub 4}]FCl to adopt isolated [MnO{sub 4}FCl] rather than corner-sharing octahedra as observed in BaMn{sup III}[PO{sub 4}]F{sub 2}. - Highlights: • Two novel phosphate halides BaMn[PO{sub 4}]FCl and BaMn[PO{sub 4}]F{sub 2} have been prepared. • These new compounds adopt different types of layered structures. • They have different molecular vibration modes and thermal stabilities. • BaMn[PO{sub 4}]FCl has weaker antiferromagnetic interactions than BaMn[PO{sub 4}]F{sub 2}. • The former adopts isolated octahedra whereas the latter adopts octahedral chains.« less

Paramagnetic resonance of Mn4+ and Mn2+ centers in lanthanum gallate single crystals

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Potapov, A. P.; Guseva, V. B.; Artyomov, M. Yu.

2010-03-01

An increase in the manganese concentration in lanthanum gallate in the range 0.5-5.0% has been found to result in a complete replacement of individual Mn4+ ions by Mn2+ ions. The relative concentrations and binding energies of individual Mn4+, Mn3+, and Mn2+ ions have been determined. The spin Hamiltonians of the Mn2+ and Mn4+ centers in the rhombohedral and orthorhombic phases, respectively, have been constructed and the orientation of the principal axes of the fine-structure tensor of Mn4+ at room temperature has been found. The possibility of using electron paramagnetic resonance for determining the rotation angles of oxygen octahedra of lanthanum gallate with respect to the perovskite structure has been discussed.

Development and Evaluation of a Manganese and Iron Food Frequency Questionnaire for Pediatrics

PubMed Central

Zipkin, Frida B; Falciglia, Grace A; Kuhnell, Pierce; Haynes, Erin N

2017-01-01

Manganese (Mn) is an essential nutrient, but overexposure can lead to neurotoxicity. Given the essentiality of Mn in the diet, particularly during children’s growth and development, it is imperative to quantify dietary Mn intake in populations that may be exposed to industrial sources of Mn. Dietary absorption of Mn is inversely associated with iron (Fe) stores, yet there is currently no food frequency questionnaire (FFQ) to assess dietary Mn and Fe intake. The study objective was to develop and evaluate the validity of a FFQ to measure dietary Mn and Fe intake in pediatrics by comparing the estimated intakes of Mn and Fe with biomarkers: Mn in blood and hair and Fe in serum. This study utilized a subset of the Communities Actively Researching Exposure Study (CARES) population residing in Guernsey County, Ohio. Dietary Mn was not correlated with either blood or hair Mn; however, dietary Mn and serum ferritin were significantly correlated, with a correlation coefficient of 0.51, p < 0.01. Moreover, dietary Fe and serum ferritin were also significantly correlated, with a correlation coefficient of 0.51, p < 0.01. This FFQ is a valid measurement tool for Fe intake as measured by serum ferritin; however, Mn intake did not correlate with either blood or hair Mn. PMID:28906436

Development and Evaluation of a Manganese and Iron Food Frequency Questionnaire for Pediatrics.

PubMed

Zipkin, Frida B; Falciglia, Grace A; Kuhnell, Pierce; Haynes, Erin N

2017-09-14

Manganese (Mn) is an essential nutrient, but overexposure can lead to neurotoxicity. Given the essentiality of Mn in the diet, particularly during children's growth and development, it is imperative to quantify dietary Mn intake in populations that may be exposed to industrial sources of Mn. Dietary absorption of Mn is inversely associated with iron (Fe) stores, yet there is currently no food frequency questionnaire (FFQ) to assess dietary Mn and Fe intake. The study objective was to develop and evaluate the validity of a FFQ to measure dietary Mn and Fe intake in pediatrics by comparing the estimated intakes of Mn and Fe with biomarkers: Mn in blood and hair and Fe in serum. This study utilized a subset of the Communities Actively Researching Exposure Study (CARES) population residing in Guernsey County, Ohio. Dietary Mn was not correlated with either blood or hair Mn; however, dietary Mn and serum ferritin were significantly correlated, with a correlation coefficient of 0.51, p < 0.01. Moreover, dietary Fe and serum ferritin were also significantly correlated, with a correlation coefficient of 0.51, p < 0.01. This FFQ is a valid measurement tool for Fe intake as measured by serum ferritin; however, Mn intake did not correlate with either blood or hair Mn.

Sulfur Mediated Alleviation of Mn Toxicity in Polish Wheat Relates to Regulating Mn Allocation and Improving Antioxidant System

PubMed Central

Sheng, Huajin; Zeng, Jian; Liu, Yang; Wang, Xiaolu; Wang, Yi; Kang, Houyang; Fan, Xing; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

2016-01-01

Sulfur (S) is an essential macronutrient that has been proved to play an important role in regulating plant responses to various biotic and abiotic stresses. The present study was designed to investigate the effect of S status on polish wheat plant response to Mn toxicity. Results showed that Mn stress inhibited plant growth, disturbed photosynthesis and induced oxidative stress. In response to Mn stress, polish wheat plant activated several detoxification mechanisms to counteract Mn toxicity, including enhanced antioxidant defense system, increased Mn distribution in the cell wall and up-regulated genes involved in S assimilation. Moderate S application was found to alleviate Mn toxicity mainly by sequestering excess Mn into vacuoles, inhibiting Mn translocation from roots to shoots, stimulating activities of antioxidant enzymes and enhancing GSH production via up-regulating genes involved in S metabolism. However, application of high level S to Mn-stressed plants did not significantly alleviated Mn toxicity likely due to osmotic stress. In conclusion, moderate S application is beneficial to polish wheat plant against Mn toxicity, S exerts its effects via stimulating the antioxidant defense system and regulating the translocation and subcellular distribution of Mn, in which processes GSH plays an indispensable role. PMID:27695467

New Defective Brannerite-Type Vanadates. I. Synthesis and Study of Mn 1- x- yφ xNa yV 2-2 x-yMo 2 x+yO 6 Solid Solutions

NASA Astrophysics Data System (ADS)

Masłowska, Bogna; Ziółkowski, Jacek

1994-05-01

MnV 2O 6 of the brannerite-type structure (below 540°C) doped with MoO 3 and Na 2O forms isomorphous solid solutions MnNaφ = Mn 1- x-yφ xNa yV 2-2 x-yMo 2 x+ yO 6 (φ cation vacancy in the original Mn position), belonging to the pseudoternary MnV 2O 6-NaVMoO 6-MoO 3 system. Particular cases are MnNa = Mn 1- yNa y V 2- yMo yO 6 ( x = 0), Mnφ = Mn 1- xφ xV 2-2 xMo 2 xO 6 ( y = 0), and Naφ = Na 1- xφ xV 1- xMo 1+ xO 6 ( x + y = 1). MnV 2O 6 and NaVMoO 6 show miscibility in the entire composition range (MnNa). The opposite boundary of MnNaφ passes through the (100 x, 100 y) points (45, 0), (33, 30), and (30, 70). The phase diagram of the pseudobinary MnV 2O 6-NaVMoO 6 system (determined with DTA) shows (i) a narrow double-lens-type solidus-liquidus gap at high values of y , (ii) two peritectic meltings at lower y (yielding the high temperature β-MnNa and Mn 2V 2O 7), and (iii) little area of β-MnNa. Lattice parameters of MnNa (determined with X-ray diffraction) reveal small deviations from Vegard's law. As the ionic radii of both dopants (Na + and Mo 6+) are, respectively, larger than those of mother ions (Mn 2+ and V 5+), the unit cell increases in all directions with rising y along the MnNa series of solid solutions. However, due to the anisotropy of the structure, parameter c is strongly sensitive to Na/Mn substitution, b is ruled by Mo/V, and a is weakly influenced by Mo/V. Close analogy to the behavior of the previously studied MnV 2O 6-LiVMoO 6-MoO 6 system is discussed.

Experimental determination of activities in FeTiO3-MnTiO3 ilmenite solid solution by redox reversals

NASA Astrophysics Data System (ADS)

Feenstra, A.; Peters, Tjerk

1996-12-01

Solid solutions of (Fe,Mn)TiO3 were synthesized, mostly at 0.10 XMn intervals, at 1 bar, 900°C and log f O 2 = 17.50. Analysis by EMP indicate an ideal stoichiometry for the Fe-Mn ilmenites with (Fe+Mn) = Ti = 1.000 when normalized to 3 oxygens. Their unit cell volume increases linearly with XMn. The composition of Fe-Mn ilmenite coexisting with metallic Fe and rutile was reversed at 1 bar, 700 900°C and fixed f O 2 in a gas-mixing furnace. Oxygen fugacity was controlled by mixing CO2 and H2 gas and was continuously monitored with an yttrium-stabilized zirconia electrolyte. Solution properties of Fe-Mn ilmenite were derived from the experimental data by mathematical programming (Engi and Feenstra, in preparation) including notably the results of Fe-Mn exchange experiments between ilmenite and garnet (Feenstra and Engi, submitted) and anchoring the standard state properties to the updated thermodynamic dataset of Berman and Aranovich (1996). The thermodynamic analysis resulted in positive deviations from ideality for (Fe,Mn)TiO3 ilmenite, which is well described by an asymmetric Margules model with WH FeFeMn = 9.703 and WH FeMnMn = 23.234 kJ/mol, WS FeFeMn = 19.65 and WS FeMnMn = 22.06 J/(K·mol). The excess free energy for Fe-Mn ilmenite derived from the redox reversals is larger than in the symmetric ilmenite model (WG FeMn = +2.2 kJ/mol) determined by O'Neill et al. from emf measurements on the assemblage iron-rutile-(Fe,Mn)ilmenite.

Investigation of Y6Mn23 and YMn12 intermetallic alloys under high hydrogen pressure

NASA Astrophysics Data System (ADS)

Filipek, S. M.; Sato, R.; Kuriyama, N.; Tanaka, H.; Takeichi, N.

2010-03-01

Among three intermetallic compounds existing in Y-Mn system the YMn2 and Y6Mn23 can easily form interstitial hydrides while for YMn12 existence of hydride has never been reported. At moderate hydrogen pressure YMn2 and Y6Mn23 transform into YMn2H4.5 and Y6Mn23H25 respectively. At high hydrogen pressure the YMn2 (C15 or C14 parent structure) forms a unique YMn2H6 (s.g. Fm3m) complex hydride of fluorite structure in which one Mn atom Mn(1) and Y randomly occupy the 8c sites while second manganese (Mn2) in position 4a forms complex anion with 6 hydrogen atoms located in positions 24e. Formation of YMn2H6 independently of the structure of parent phase (C14 or C15) as well as occupation of the same site (8c) by Y and Mn(1) atoms suggested that also Y6Mn23 and YMn12 could transform into YMn2H6 - type hydride in which suitable number of Y atoms will be substituted by Mn(1) in the 8c positions. This assumption was confirmed by exposing R6Mn23 and RMn12 to 1 GPa of hydrogen pressure at 1000C. Formation of (RxMn2-x)MnH6 (where x = 18/29 or 3/13 for R6Mn23 and RMn12 hydrides respectively) was confirmed by XRD. Hydrogen concentration in both R6Mn23 and RMn12 based hydrides reached H/Me = 2 thus value two times higher than in R6Mn23H25.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lecointre, A., E-mail: lecointre.aurelie@gmail.com; Bessière, A., E-mail: aurelie-bessiere@chimie-paristech.fr; Department of Physics, Goa University, Taleigao Plateau, Goa 403 206

Highlights: ► Long-lasting phosphorescence of CaMgSi{sub 2}O{sub 6}:Mn is studied for bioimaging application. ► CaMgSi{sub 2}O{sub 6}:Mn yields orange and red luminescence of Mn{sup II}{sub Ca} and Mn{sup II}{sub Mg}, respectively. ► Red Mn{sup II}{sub Mg} emission dominates long-lasting phosphorescence spectra. ► Mn mainly substitutes Mg. ► Mn{sup II}{sub Mg} plays the role of hole trap in the persistent luminescence mechanism. - Abstract: Materials with red long-lasting phosphorescence, such as Mn{sup II}-doped diopsides, can be used for small animal in vivo imaging. CaMgSi{sub 2}O{sub 6}:Mn powders with various amounts of Mn were prepared by sol–gel to investigate their long-lasting phosphorescencemore » mechanism. X-ray diffraction, X-ray absorption fine and near-edge structure and electron paramagnetic resonance showed that manganese is quantitatively introduced in the structure as Mn{sup II}. Most of the Mn doping ions substitute Mg and possess a highly elongated octahedral environment. While photoluminescence and X-ray excited optical luminescence spectra show both orange (585 nm) and red (685 nm) {sup 4}T{sub 1} ({sup 4}G) → {sup 6}A{sub 1} ({sup 6}S) emission of Mn{sup II}{sub Ca} and Mn{sup II}{sub Mg}, respectively, Mn{sup II}{sub Mg} red emission dominates long-lasting phosphorescence and thermally stimulated luminescence spectra. These results point to Mn{sup II}{sub Mg} as the preferential hole trap and recombination center in the long-lasting phosphorescence mechanism. An intense persistent red emission suitable for in vivo imaging probes is obtained for the highest nominal Mn content (7.5%)« less

Understanding the role of manganese dioxide in the oxidation of phenolic compounds by aqueous permanganate.

PubMed

Jiang, Jin; Gao, Yuan; Pang, Su-Yan; Lu, Xue-Ting; Zhou, Yang; Ma, Jun; Wang, Qiang

2015-01-06

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2.

Preparation and properties of a monomeric Mn(IV)-oxo complex.

PubMed

Parsell, Trenton H; Behan, Rachel K; Green, Michael T; Hendrich, Michael P; Borovik, A S

2006-07-12

Manganese-oxo complexes have long been investigated because of their proposed roles in biological and chemical catalysis. However, there are few examples of monomeric complexes with terminal oxo ligands, especially those with oxomanganese(IV) units. A oxomanganese(IV) complex has been prepared from [MnIIIH3buea(O)]2- ([H3buea]3-, tris[(N'-tert-butylureaylato)-N-ethylene]aminato), a monomeric MnIII-O complex in which the oxo ligand arises from cleavage of dioxygen. Treating [MnIIIH3buea(O)]2- with [Cp2Fe]BF4 in either DMF at -45 degrees C or DMSO at room temperature produces [MnIVH3buea(O)]-: lambdamax = 635 nm; nu(Mn-16O) = 737 cm-1; nu(Mn-18O) = 709 cm-1; g = 5.15, 2.44, 1.63, D = 3.0 cm-1, E/D = 0.26, aMn = 66 G (A = 190 MHz). These spectroscopic properties support the assignment of a mononuclear MnIV-oxo complex with an S = 3/2 ground state. Density functional theory supports this assignment and the Jahn-Teller distortion around the high-spin MnIV center that would alter the molecular structure of [MnIVH3buea(O)]- from trigonal symmetry (as indicated by the highly rhombic EPR signal). [MnIVH3buea(O)]- is relatively unstable in DMSO, converting to [MnIIIH3buea(OH)]- via a proposed X-H bond cleavage. [MnIVH3buea(O)]- reacts with 1,2-diphenylhydrazine to from azobenzene (95% yield) and [MnIIIH3buea(OH)]-. The MnIV-oxo does not react with triphenyl- or tricyclohexylphosphine. However, O-atom transfer is observed with methyldiphenylphosphine and dimethylphenylphosphine, producing the corresponding phosphine oxides. These results illustrate the diverse reactivity of the MnIV-oxo unit.