Natural and anthropogenic processes that concentrate Mn in rural and urban environments of the lower Mississippi River Delta

International Nuclear Information System (INIS)

Mielke, H.W.; Gonzales, C.R.; Powell, E.; Shah, A.; Mielke, P.W.

2002-01-01

This study evaluated natural processes and projected ethyl cyclopentadienyl manganese tricarbonyl fuel additives as sources of Mn accumulation in the environment. Data sets include fresh alluvium and sediments from the lower Mississippi River Delta and a soil metal survey of metropolitan New Orleans. The (1) railroad Mn, (2) industrial Mn, and (3) dynamic aquifer-stream transfer of Mn hypotheses were tested with the Mississippi River Delta data. Friction between Mn-rich steel wheels and rails contributes Mn (P=0.017) to the environment, supporting (1). Sediment loads of Mn were similar (P=0.77) upstream and downstream from the Louisiana industrial corridor, not supporting (2). The median Mn on the alluvium surface (59 mg/kg), in the aquifer (159 mg/kg), and in the riverbank aquifer discharge zone (513 mg/kg) support (3) as a mechanism for Mn enrichment of lay. The New Orleans soil metal survey data set shows a rural to urban increase of fourfold for Mn and three orders of magnitude for Pb. At 1999 .S. highway fuel use, 8.3 mg of Mn per L would yield 5000 metric tons of Mn annually. If 13% of Mn were emitted, 650 tons of Mn would become aerosols annually, while 87% or 4350 tons would remain in engines. The 1999 toxic release inventory for Mn shows 370 tons as total emissions compared to the potential of 390 and 260 tons from vehicles, respectively, in urban and rural areas. A precautionary lesson from the use of Pb as a fuel additive is that the use of Mn as a fuel additive would be associated with an increased risk or neonates exceeding the estimated total tolerable daily intake of .1-16.5μg Mn (especially in urban inner city environments) because neonates lack fully functional hepatic clearance for Mn

Outline

Indian Academy of Sciences (India)

First page Back Continue Last page Graphics. Outline. Cotton trends in India. The need for Bollgard cotton. Evaluation & approval. Safety; Field evaluation. Key statistics. Input Costs, Pesticide spend, Profit per acre; Area, Production, Productivity, etc. Value generated. 2005; 2006 Estimates. Summary.

Mn bioavailability by polarized Caco-2 cells: comparison between Mn gluconate and Mn oxyprolinate

Directory of Open Access Journals (Sweden)

Fulgenzi Alessandro

2011-07-01

Full Text Available Abstract Background Micronutrient inadequate intake is responsible of pathological deficiencies and there is a need of assessing the effectiveness of metal supplementation, frequently proposed to rebalance poor diets. Manganese (Mn is present in many enzymatic intracellular systems crucial for the regulation of cell metabolism, and is contained in commercially available metal supplements. Methods We compared the effects of two different commercial Mn forms, gluconate (MnGluc and oxyprolinate (MnOxP. For this purpose we used the polarized Caco-2 cells cultured on transwell filters, an established in vitro model of intestinal epithelium. Since micronutrient deficiency may accelerate mitochondrial efficiency, the mitochondrial response of these cells, in the presence of MnGluc and MnOxP, by microscopy methods and by ATP luminescence assay was used. Results In the presence of both MnOxP and MnGluc a sustained mitochondrial activity was shown by mitoTraker labeling (indicative of mitochondrial respiration, but ATP intracellular content remained comparable to untreated cells only in the presence of MnOxP. In addition MnOxP transiently up-regulated the antioxidant enzyme Mn superoxide dismutase more efficiently than MnGluc. Both metal treatments preserved NADH and βNADPH diaphorase oxidative activity, avoided mitochondrial dysfunction, as assessed by the absence of a sustained phosphoERK activation, and were able to maintain cell viability. Conclusions Collectively, our data indicate that MnOxP and MnGluc, and primarily the former, produce a moderate and safe modification of Caco-2 cell metabolism, by activating positive enzymatic mechanisms, thus could contribute to long-term maintenance of cell homeostasis.

Lessons for Implementation from the World's Most Successful Programme: The Global Eradication of Smallpox.

Science.gov (United States)

Pratt, David

1999-01-01

Focuses on lessons educators might learn from the Intensified Campaign for the Global Eradication of Smallpox. Outlines the history of smallpox eradication. Discusses the eradication effort's obstacles, campaign, and costs and benefits. Considers five factors relevant to the successful implementation of educational programs. (CMK)

Lessons learned in terms of crisis management

International Nuclear Information System (INIS)

2006-01-01

This document outlines that nobody was prepared to the crisis which occurred after the Chernobyl accident, whether in Russia, Europe or France. In order to illustrate the fact that crisis management has been different from one country to another, the report describes how the crisis has been managed in Norway (which has been quickly reached by fallouts and with a rather high level) and in Switzerland. It comments radioactivity measurements performed in France during spring 1986 by the SCPRI, the CEA and the ISPN. It discusses the lessons drawn in France in terms of emergency situation management regarding the protection of the population, crisis management, and the French post-accidental doctrine. It comments the lessons drawn in eastern European countries, with the cooperative implication of the IRSN. International projects are evoked: the Chernobyl Centre, the French-German Initiative, the European projects (EURANOS, NERIS, FARMING, STRATEGY, MOSES and SAMEN)

Kinetic Investigations of SiMn Slags From Different Mn Sources

Science.gov (United States)

Kim, Pyunghwa Peace; Tangstad, Merete

2018-03-01

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.

CoMStOC vs. International Solar Month - Experience gained and lessons learned from SMM campaigns

Science.gov (United States)

Schmelz, J. T.

1991-01-01

The factors that should be addressed by the organizers of a solar observing campaign are outlined and described. Two recent solar observing campaigns are compared and discussed. Lessons learned from these and other campaigns involving the SMM satellite are analyzed and advice for future campaigns is offered.

The Mn site in Mn-doped GaAs nanowires: an EXAFS study

International Nuclear Information System (INIS)

D’Acapito, F; Rovezzi, M; Boscherini, F; Jabeen, F; Bais, G; Piccin, M; Rubini, S; Martelli, F

2012-01-01

We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs nanowires. Mn doping has been obtained either via the diffusion of the Mn used as seed for the nanowire growth or by providing Mn during the growth of Au-induced wires. As a general finding, we observe that Mn forms chemical bonds with As but is not incorporated in a substitutional site. In Mn-induced GaAs wires, Mn is mostly found bonded to As in a rather disordered environment and with a stretched bond length, reminiscent of that exhibited by MnAs phases. In Au-seeded nanowires, along with stretched MnAs coordination, we have found the presence of Mn in a MnAu intermetallic compound. (paper)

Antiferromagnetic MnN layer on the MnGa(001) surface

Energy Technology Data Exchange (ETDEWEB)

Guerrero-Sánchez, J., E-mail: guerrero@cnyn.unam.mx; Takeuchi, Noboru

2016-12-30

Highlights: • A ferromagnetic Gallium terminated surface is stable before N incorporation. • After N incorporation, an antiferromagnetic MnN layer becomes stable in a wide range of chemical potential. • Spin density distribution shows an antiferromagnetic/ferromagnetic (MnN/MnGa) arrangement at the surface. - Abstract: Spin polarized first principles total energy calculations have been applied to study the stability and magnetic properties of the MnGa(001) surface and the formation of a topmost MnN layer with the deposit of nitrogen. Before nitrogen adsorption, surface formation energies show a stable gallium terminated ferromagnetic surface. After incorporation of nitrogen atoms, the antiferromagnetic manganese terminated surface becomes stable due to the formation of a MnN layer (Mn-N bonding at the surface). Spin density distribution shows a ferromagnetic/antiferromagnetic arrangement in the first surface layers. This thermodynamically stable structure may be exploited to growth MnGa/MnN magnetic heterostructures as well as to look for exchange biased systems.

Travel Agent Course Outline.

Science.gov (United States)

British Columbia Dept. of Education, Victoria.

Written for college entry-level travel agent training courses, this course outline can also be used for inservice training programs offered by travel agencies. The outline provides information on the work of a travel agent and gives clear statements on what learners must be able to do by the end of their training. Material is divided into eight…

Fourier transform spectroscopy of MnH and MnD

Science.gov (United States)

Balfour, W. J.; Launila, O.; Klynning, L.

Two infrared band systems, centred near 846 nm and 1060 nm in both MnH and MnD have been rotationally analysed and shown to have a common lower state. The electronic transitions lie within the quintet manifold and are here designated c 5Σ-a 5Σ and b 5Πi-a 5Σ for the 846 and 1060 nm systems, respectively. In the 846 nm system in MnH all 10 main branches have been found in the 0-0 and 1-1 bands, while in MnD the data are complete only for 0-0. Satellite branches have been identified in the 1060 nm system and all spin and Λ-type doublings have been established. The number of assigned 0-0 branches in the 1060 nm system is 35 for MnH and 37 for MnD. Molecular constants have been determined for all three states involved. Λ-doubling diagrams are presented for b 5Πi state with v = 1, 2 levels in MnH and with the v = 2 level in MnD. Local perturbations in c5Σ (v = 1) in MnH are suspected to originate from the v = 3 level of b 5Πi.

Tuning the magnetic properties of GaAs:Mn/MnAs hybrids via the MnAs cluster shape

International Nuclear Information System (INIS)

Nidda, H-A Krug von; Kurz, T; Loidl, A; Hartmann, Th; Klar, P J; Heimbrodt, W; Lampalzer, M; Volz, K; Stolz, W

2006-01-01

We report a systematic study of ferromagnetic resonance in granular GaAs:Mn/MnAs hybrids grown on GaAs(001) substrates by metal-organic vapour-phase epitaxy. The ferromagnetic resonance of the MnAs clusters can be resolved at all temperatures below T c . An additional broad absorption is observed below 60 K and is ascribed to localized charge carriers of the GaAs:Mn matrix. The anisotropy of the MnAs ferromagnetic resonance field originates from the magneto-crystalline field and demagnetization effects of the ferromagnetic MnAs clusters embedded in the GaAs:Mn matrix. Its temperature dependence basically scales with magnetization. Comparison of the observed angular dependence of the resonance field with model calculations yields the preferential orientation and shape of the clusters formed in hybrid layers of different thickness (150-1000 nm) grown otherwise at the same growth conditions. The hexagonal axes of the MnAs clusters are oriented along the four cubic GaAs space diagonals. Thin layers contain lens-shaped MnAs clusters close to the surface, whereas thick layers also contain spherical clusters in the bulk of the layer. The magnetic properties of the hexagonal MnAs clusters can be tuned by a controlled variation of the cluster shape

The Algebra Teacher's Guide to Reteaching Essential Concepts and Skills 150 Mini-Lessons for Correcting Common Mistakes

CERN Document Server

Muschla, Judith A; Muschla, Erin

2011-01-01

Easy to apply lessons for reteaching difficult algebra concepts Many students have trouble grasping algebra. In this book, bestselling authors Judith, Gary, and Erin Muschla offer help for math teachers who must instruct their students (even those who are struggling) about the complexities of algebra. In simple terms, the authors outline 150 classroom-tested lessons, focused on those concepts often most difficult to understand, in terms that are designed to help all students unravel the mysteries of algebra. Also included are reproducible worksheets that will assist teachers in reviewing and r

Identification of the interstitial Mn site in ferromagnetic (Ga,Mn)As

CERN Document Server

AUTHOR|(CDS)2093111; Wahl, Ulrich; Augustyns, Valerie; Silva, Daniel; Granadeiro Costa, Angelo Rafael; Houben, K; Edmonds, Kevin W; Gallagher, BL; Campion, RP; Van Bael, MJ; Castro Ribeiro Da Silva, Manuel; Martins Correia, Joao; Esteves De Araujo, Araujo Joao Pedro; Temst, Kristiaan; Vantomme, André; Da Costa Pereira, Lino Miguel

2015-01-01

We determined the lattice location of Mn in ferromagnetic (Ga,Mn)As using the electron emission channeling technique. We show that interstitial Mn occupies the tetrahedral site with As nearest neighbors (TAs) both before and after thermal annealing at 200 °C, whereas the occupancy of the tetrahedral site with Ga nearest neighbors (TGa) is negligible. TAs is therefore the energetically favorable site for interstitial Mn in isolated form as well as when forming complexes with substitutional Mn. These results shed new light on the long standing controversy regarding TAs versus TGa occupancy of interstitial Mn in (Ga,Mn)As.

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}-.

Science.gov (United States)

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

Inadequacies of Belgium nuclear emergency plans: lessons from the Fukushima catastrophe have not been learned

International Nuclear Information System (INIS)

Boilley, David; Josset, Mylene

2015-01-01

After having outlined that some Belgium regional authorities made some statements showing that they did not learn lessons neither from the Chernobyl catastrophe, nor from the Fukushima accident, this report aims at examining whether Belgium is well prepared to face a severe nuclear accident occurring within its borders or in neighbouring countries, whether all hypotheses have actually been taken into account, and whether existing emergency plans are realistic. After a presentation of Belgium's situation regarding nuclear plants (Belgium plants and neighbouring French plants), the report presents the content and organisation of the nuclear emergency plan for the Belgium territory at the national, provincial and municipal levels. While outlining inadequacies and weaknesses of the Belgium plan regarding the addressed issues, it discusses the main lessons learned from the Fukushima accident in terms of emergency planning areas, of population sheltering, of iodine-based prophylaxis, of population evacuation, of food supply, of tools (measurement instruments) and human resources, and of public information. In the next parts, the report addresses and discusses trans-border issues, and the commitment of stakeholders

Nano-sized Mn3O4 and β-MnOOH from the decomposition of β-cyclodextrin-Mn: 2. The water-oxidizing activities.

Science.gov (United States)

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.

Fostering sustainable small-scale investments: lessons from experience and ideas for intervention and innovation

International Nuclear Information System (INIS)

Lucia, R.J. de

2000-01-01

This article presents lessons from experience pertinent to implementing small-scale natural resource and related investment projects in developing countries. It outlines ideas for intervention and innovation to foster such investments. Particular emphasis is placed on private-sector participation in these investments. Following a brief presentation of the economic development and other arguments that support intervention and innovation in support of such small-scale natural resource investments, the article discusses many of the lessons learned from experience. These lessons reinforce those touched upon in the investment-specific discussions in the previous articles. The experience and associated lessons that are examined include experiences in both developing and developed countries and encompass nor just lessons from natural resource investments, but also small-scale investments in other sectors. Financing and other innovations which facilitate meeting the challenges are drawn from relevant experience where barriers to investment have been surmounted. Options for programme and project interventions to increase market penetration of small-scale investments and achieve the associated development linkages and synergies are suggested. These suggestions are aimed especially at governments and bilateral and multilateral development finance and development assistance entities. It is those players who might support such interventions in collaboration with local financial institutions and other market players. (author)

National Environmental Outline 1997-2020. 4

International Nuclear Information System (INIS)

1997-01-01

According to the Dutch Law on Environmental Protection ('Wet Milieubeheer') every four years an environmental outline is drafted as a preparation for the national environmental plan (NMP3). In a separate publication (the background document) a methodical and numerical basis and account is given by means of data and literature references of the environmental outline. This main report, the outline, comprises an analysis of the expected bottlenecks and an outline of a number of solutions in order to determine the effectiveness of the current policy by means of which targets must be realized and how future policy could solve the most important bottlenecks. refs

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

Science.gov (United States)

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.

Mn-substituted perovskites RECoxMn1-xO3: a comparison between magnetic properties of LaCoxMn1-xO3 and GdCoxMn1-xO3

Directory of Open Access Journals (Sweden)

Barahona, P.

2008-08-01

Full Text Available Cooperative phenomena constitute important mechanisms to explain the magnetic properties of the perovskite manganites REMnO3, in which the rare-earth and/or Mn is partially replaced by divalent elements. In this way, the manganese ion changes its valence state (Mn3+ Mn4+, triggering strong magnetic interactions. In this work we describe the case of GdCoxMn1-xO3 (0.0 ≤ x ≤ 1.0 for which the antiferromagnetic interaction between the Gd sublattice and the Mn/Co network leads to a reversal of the magnetic moment at low temperature. No inversion is observed for the LaCoxMn1-xO3 series, in which the ordering temperature may attain a maximum of 235 K for LaCo0.50Mn0.50O3, while it is only 120 K for similar Co/Mn ratio in the case of GdCo0.50Mn0.50O3. Magnetic properties are described in terms of two regimes: one, for x 3 manganite and another one, for x > 0.5, when Mn substitutes Co in the GdCoO3 cobaltite, while the magnetic interactions are maximized at x(Co = 0.50. This hypothesis is discussed in terms of the respective oxidation states of both manganese (Mn3+ / Mn4+ and cobalt (Co2+ / Co3+.El fenómeno cooperativo constituye un importante mecanismo para explicar las propiedades magnéticas de las perovskitas manganitas TRMnO3, en las que el catión de tierra rara, TR, y/o el catión Mn3+ son parcialmente reemplazados por cationes divalentes. Por esta vía el ión de manganeso cambia de estado de valencia (Mn3+ Mn4+, generando fuertes interacciones magnéticas. En el presente trabajo se describe el caso de las soluciones sólidas GdCoxMn1-xO3 (0.0 ≤ x ≤ 1.0 para las que la interacción antiferromagnética entre la subred del Gd3+ y la red Mn/Co lleva a una inversión del momento magnético a baja temperatura. No se ha observado inversión para la serie LaCoxMn1-xO3, en que la temperatura de orden puede alcanzar un máximo de 235K para LaCo0.50Mn0.50O3, mientras que en el caso de GdCo0.50Mn0.50O3, en que sí se observa inversión, la

Tempering of Mn and Mn-Si-V dual-phase steels

Science.gov (United States)

Speich, G. R.; Schwoeble, A. J.; Huffman, G. P.

1983-06-01

Changes in the yield behavior, strength, and ductility of a Mn and a Mn-Si-V d11Al-phase (ferrite-martensite) steel were investigated after tempering one hour at 200 to 600 °C. The change in yield behavior was complex in both steels with the yield strength first increasing and then decreasing as the tempering temperature was increased. This complex behavior is attributed to a combination of factors including carbon segregation to dislocations, a return of discontinuous yielding, and the relief of resid11Al stresses. In contrast, the tensile strength decreased continuously as the tempering temperature was increased in a manner that could be predicted from the change in hardness of the martensite phase using a simple composite strengthening model. The initial tensile ductility (total elongation) of the Mn-Si-V steel was much greater than that of the Mn steel. However, upon tempering up to 400 °C, the ductility of the Mn-Si-V decreased whereas that of the Mn steel increased. As a result, both steels had similar ductilities after tempering at 400 °C or higher temperatures. These results are attributed to the larger amounts of retained austenite in the Mn-Si-V steel (9 pct) compared to the Mn steel (3 pct) and its contribution to tensile ductility by transforming to martensite during plastic straining. Upon tempering at 400 °C, the retained austenite decomposes to bainite and its contribution to tensile ductility is eliminated.

Valence state of Mn in Ca-doped LaMnO3 studied by high-resolution Mn K ß emission spectroscopy

NARCIS (Netherlands)

Tyson, T.A.; Qian, Q.; Kao, C.-C.; Rueff, J.-P.; Groot, F.M.F. de; Croft, M.; Cheong, S.-W.; Greenblatt, M.; Subramanian, M.A.

1999-01-01

Mn K ß x-ray emission spectra provide a direct method to probe the effective spin state and charge density on the Mn atom and is used in an experimental study of a class of Mn oxides. Specifically, the Mn K ß line positions and detailed spectral shapes depend on the oxidation and the spin state of

Strong correlation and ferromagnetism in (Ga,Mn)As and (Ga,Mn)N

International Nuclear Information System (INIS)

Filippetti, A.; Spaldin, N.A.; Sanvito, S.

2005-01-01

The band energies of the ferromagnetic diluted magnetic semiconductors (Ga,Mn)As and (Ga,Mn)N are calculated using a self-interaction-free approach which describes covalent and strongly correlated electrons without adjustable parameters. Both materials are half-metallic, although the contribution of Mn-derived d states to the bands around the Fermi energy is very different in the two cases. In (Ga,Mn)As the bands are strongly p-d hybridized, with a dominance of As p states. In contrast in (Ga,Mn)N the Fermi energy lies within three flat bands of mainly d character that are occupied by two electrons. Thus the Mn ion in (Ga,Mn)N behaves as a deep trap acceptor, with the hole at 1.39 eV above the GaN valence band top, and is in excellent agreement with the experimental data

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

Directory of Open Access Journals (Sweden)

Yulin Liu

2016-01-01

Full Text Available 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.

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

Science.gov (United States)

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 (Al–5Mg–Mn alloy with low Fe content (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

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al-5Mg-Mn Alloys Solidified Under Near-Rapid Cooling.

Science.gov (United States)

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 (Al-5Mg-Mn alloy with low Fe content (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.

Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

Energy Technology Data Exchange (ETDEWEB)

Cui, J., E-mail: jun.cui@pnnl.gov; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D. [Materials Sciences and Engineering Division, Ames Laboratory, Ames, Iowa 50011 (United States); Marinescu, M. [Electron Energy Corporation, Landisville, Pennsylvania 17538 (United States); Huang, Q. Z.; Wu, H. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States); Vuong, N. V.; Liu, J. P. [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States)

2014-05-07

MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ{sub B} at 50 K and 300 K, respectively.

Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

Energy Technology Data Exchange (ETDEWEB)

Cui, J; Choi, JP; Li, G; Polikarpov, E; Darsell, J; Kramer, MJ; Zarkevich, NA; Wang, LL; Johnson, DD; Marinescu, M; Huang, QZ; Wu, H; Vuong, NV; Liu, JP

2014-05-07

MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 mu(B) at 50 K and 300 K, respectively. (C) 2014 AIP Publishing LLC.

Mn(II,III) oxidation and MnO2 mineralization by an expressed bacterial multicopper oxidase

Science.gov (United States)

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

Magnetic structures of Er6Mn23 and Dy6Mn23

International Nuclear Information System (INIS)

Ouladdiaf, B.; Deportes, J.; Rodriguez-Carvajal, J.

1995-01-01

The R 6 Mn 23 (R=rare earth) compounds crystallize in the cubic Th 6 Mn 23 -type structure with space group Fm3m. Powder neutron-diffraction experiments were performed on Dy 6 Mn 23 and Er 6 Mn 23 . The magnetic unit cell coincides with the chemical one. The R moments have a ferromagnetic non-collinear arrangement, whereas the Mn moments are parallel to the [1 1 1] direction. The magnetic structures belong to the three-dimensional Γ 5g irreducible representation of Fm3m associated with the wave vector K=[0 0 0]. The spin configurations in both compounds result from the competition between the R-R, R-Mn magnetic interactions and the crystal electric field on the R ions. (orig.)

Synthesis and Electrochemistry of Li3MnO4: Mn in the +5 OxidationState

Energy Technology Data Exchange (ETDEWEB)

Saint, Juliette.A.; Doeff, Marca M.; Reed, John

2007-06-19

Computational and experimental work directed at exploringthe electrochemical properties of tetrahedrally coordinated Mn in the +5oxidation state is presented. Specific capacities of nearly 700 mAh/g arepredicted for the redox processes of LixMnO4 complexes based on twotwo-phase reactions. One is topotactic extractionof Li from Li3MnO4 toform LiMnO4 and the second is topotactic insertion of Li into Li3MnO4 toform Li5MnO4. In experiments, it is found that the redox behavior ofLi3MnO4 is complicated by disproportionation of Mn5+ in solution to formMn4+ and Mn7+ and byother irreversible processes; although an initialcapacity of about 275 mAh/g in lithiumcells was achieved. Strategiesbased on structural considerations to improve the electrochemicalproperties of MnO4n- complexes are given.

Microbial genome-wide association studies: lessons from human GWAS.

Science.gov (United States)

Power, Robert A; Parkhill, Julian; de Oliveira, Tulio

2017-01-01

The reduced costs of sequencing have led to whole-genome sequences for a large number of microorganisms, enabling the application of microbial genome-wide association studies (GWAS). Given the successes of human GWAS in understanding disease aetiology and identifying potential drug targets, microbial GWAS are likely to further advance our understanding of infectious diseases. These advances include insights into pressing global health problems, such as antibiotic resistance and disease transmission. In this Review, we outline the methodologies of GWAS, the current state of the field of microbial GWAS, and how lessons from human GWAS can direct the future of the field.

Paramagnetic resonance of Mn4+ and Mn2+ centers in lanthanum gallate single crystals

Science.gov (United States)

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.

Momocs : outline analysis using R

OpenAIRE

Bonhomme, Vincent; PICQ, Sandrine; Claude, Julien; Gaucherel, Cedric

2014-01-01

We introduce here Momocs, a package intended to ease and popularize modern mor- phometrics with R, and particularly outline analysis, which aims to extract quantitative variables from shapes. It mostly hinges on the functions published in the book entitled Modern Morphometrics Using R by Claude (2008). From outline extraction from raw data to multivariate analysis, Momocs provides an integrated and convenient toolkit to students and researchers who are, or may become, interested in describing...

Fourier transform infrared emission spectra of MnH and MnD

Science.gov (United States)

Gordon, Iouli E.; Appadoo, Dominique R. T.; Shayesteh, Alireza; Walker, Kaley A.; Bernath, Peter F.

2005-01-01

Fourier transform infrared emission spectra of MnH and MnD were observed in the ground X7Σ + electronic state. The vibration-rotation bands from v = 1 → 0 to v = 3 → 2 for MnH and from v = 1 → 0 to v = 4 → 3 for MnD were recorded at an instrumental resolution of 0.0085 cm -1. Spectroscopic constants were determined for each vibrational level and equilibrium constants were found from a Dunham-type fit. The equilibrium vibrational constant ( ωe) for MnH was found to be 1546.84518(65) cm -1, the equilibrium rotational constant ( Be) is 5.6856789(103) cm -1 and the eqilibrium bond distance ( re) was determined to be 1.7308601(47) Å.

Exploring Cultural Differences within a Pattern of Teaching "Musics": An International Comparative Study of Two Music Lessons on Video

Science.gov (United States)

Stich, Simon

2015-01-01

This paper outlines a praxiological perspective on classroom practice with the subject matter music, in order to understand two music lessons that were recorded on video, one in Sweden and one in Germany. It introduces a procedure and its methodological implications, in order to reconstruct and compare the characteristics of and the cultural…

Calix[4]arene supported clusters: a dimer of [Mn(III)Mn(II)] dimers

DEFF Research Database (Denmark)

Taylor, Stephanie M; McIntosh, Ruaraidh D; Beavers, Christine M

2011-01-01

Phosphinate ligands allow for the transformation of a calix[4]arene supported [Mn(III)(2)Mn(II)(2)] tetramer cluster motif into an unusual [Mn(III)Mn(II)](2) dimer of dimers; the clusters self-assemble in the crystal to form bi-layer arrays reminiscent of the typical packing of calixarene solvates....

ENDOR/ESR of Mn atoms and MnH molecules in solid argon

Science.gov (United States)

van Zee, R. J.; Garland, D. A.; Weltner, W., Jr.

1986-09-01

Mn atoms and MnH molecules, the latter formed by reaction between metal and hydrogen atoms, were trapped in solid argon and their ESR/ENDOR spectra measured at 4 K. At each pumping magnetic field two ENDOR lines were observed for 55Mn(I=5/2) atoms, corresponding to hyperfine transitions within the MS =±1/2 levels. Values of the hyperfine interaction constant and nuclear moment of 55Mn were derived from the six sets of data. For MnH, three sets of signals were detected: a proton ``matrix ENDOR'' line, transitions in the MS =0,±1 levels involving MI (55Mn)=1/2, 3/2, 5/2 levels, and proton transitions corresponding to νH and νH±aH. Analysis yielded the hyperfine constant aH =6.8(1) MHz and the nuclear quadrupole coupling constant Q'(55Mn)=-11.81(2) MHz. The latter compared favorably with a theoretical value derived earlier by Bagus and Schaefer. A higher term in the spin Hamiltonian appeared to be necessary to fit the proton hyperfine data.

Monodispersed MnO nanoparticles with epitaxial Mn{sub 3}O{sub 4} shells

Energy Technology Data Exchange (ETDEWEB)

Berkowitz, A E; Rodriguez, G F [Department of Physics, University of California, San Diego La Jolla, CA 92093 (United States); Hong, J I; Fullerton, E E [Center for Magnetic Recording Research, University of California-San Diego La Jolla, CA 92093 (United States); An, K; Hyeon, T [National Creative Research Initiative Center for Oxide Nanocrystalline Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Agarwal, N; Smith, D J [School of Materials and Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2008-07-07

We report the microstructural and magnetic properties of monodispersed nanoparticles (NPs) of antiferromagnetic MnO (T{sub N} = 118 K), with epitaxial ferrimagnetic Mn{sub 3}O{sub 4} (T{sub C} = 43 K) shells. Above T{sub C}, an unusually large magnetization is present, produced by the uncompensated spins (UCSs) on the surface of the MnO particles. These spins impart a net anisotropy to the MnO particles that is approximately three orders of magnitude larger than the bulk value. As a result, an anomalously high blocking temperature is exhibited by the MnO particles, and finite coercivity and exchange bias are present above T{sub C}. When field cooled below T{sub C}, a strong exchange bias was established in the Mn{sub 3}O{sub 4} shells as a result of high net anisotropy of the MnO particles. A large coercivity was also observed. Models of several aspects of the behaviour of this unusual system emphasized the essential role of the UCSs on the surfaces of the MnO NPs.

Magnetic properties of Heusler alloy Mn2RuGe and Mn2RuGa ribbons

International Nuclear Information System (INIS)

Yang, Ling; Liu, Bohua; Meng, Fanbin; Liu, Heyan; Luo, Hongzhi; Liu, Enke; Wang, Wenhong; Wu, Guangheng

2015-01-01

Heusler alloys Mn 2 RuGe and Mn 2 RuGa have been prepared by melt-spinning method successfully. Theoretical and experimental studies reveal a ferrimagnetic ground state in the two alloys. The Curie temperatures are 303 K for Mn 2 RuGe and 272 K for Mn 2 RuGa. The calculated total spin moments of Mn 2 RuGe and Mn 2 RuGa are integral values of 2.00 μ B and 1.03 μ B , respectively. And the theoretical spin polarization ratio is also quite high. However, due to the atomic disorder in the ribbons, the saturation moments of them measured at 5 K are smaller than the calculated values, especially that of Mn 2 RuGa. This coincides with the disappearance of the superlattice reflection (111) and (200) peaks in the XRD pattern of Mn 2 RuGa. Annealing Mn 2 RuGa ribbon at 773 K can enhance the atomic ordering. Both saturation magnetic moment and Curie temperature increase obviously after the heat treatment. - Highlights: • Mn 2 RuGe and Mn 2 RuGa have been prepared by melt-spinning successfully. • Ferrimagnetic ground state has been confirmed in Mn 2 RuGe and Mn 2 RuGa. • High spin polarization has been predicted in Mn 2 RuGe. • Melt-spinning can be a possible way to adjust the atomic order of Heusler alloys

Electrochemical performances of LiMnPO4 synthesized from non-stoichiometric Li/Mn ratio.

Science.gov (United States)

Xiao, Jie; Chernova, Natasha A; Upreti, Shailesh; Chen, Xilin; Li, Zheng; Deng, Zhiqun; Choi, Daiwon; Xu, Wu; Nie, Zimin; Graff, Gordon L; Liu, Jun; Whittingham, M Stanley; Zhang, Ji-Guang

2011-10-28

In this paper, the influences of the lithium content in the starting materials on the final performances of as-prepared Li(x)MnPO(4) (x hereafter represents the starting Li content in the synthesis step which does not necessarily mean that Li(x)MnPO(4) is a single phase solid solution in this work.) are systematically investigated. It has been revealed that Mn(2)P(2)O(7) is the main impurity when Li Li(3)PO(4) begins to form once x > 1.0. The interactions between Mn(2)P(2)O(7) or Li(3)PO(4) impurities and LiMnPO(4) are studied in terms of the structural, electrochemical, and magnetic properties. At a slow rate of C/50, the reversible capacity of both Li(0.5)MnPO(4) and Li(0.8)MnPO(4) increases with cycling. This indicates a gradual activation of more sites to accommodate a reversible diffusion of Li(+) ions that may be related to the interaction between Mn(2)P(2)O(7) and LiMnPO(4) nanoparticles. Among all of the different compositions, Li(1.1)MnPO(4) exhibits the most stable cycling ability probably because of the existence of a trace amount of Li(3)PO(4) impurity that functions as a solid-state electrolyte on the surface. The magnetic properties and X-ray absorption spectroscopy (XAS) of the MnPO(4)·H(2)O precursor, pure and carbon-coated Li(x)MnPO(4) are also investigated to identify the key steps involved in preparing a high-performance LiMnPO(4). This journal is © the Owner Societies 2011

Low-temperature molar heat capacities and entropies of MnO2 (pyrolusite), Mn3O4 (hausmanite), and Mn2O3 (bixbyite)

Science.gov (United States)

Robie, R.A.; Hemingway, B.S.

1985-01-01

Pyrolusite (MnO2), hausmanite (Mn3O4), and bixbyite (Mn2O3), are important ore minerals of manganese and accurate values for their thermodynamic properties are desirable to understand better the {p(O2), T} conditions of their formation. To provide accurate values for the entropies of these important manganese minerals, we have measured their heat capacities between approximately 5 and 380 K using a fully automatic adiabatically-shielded calorimeter. All three minerals are paramagnetic above 100 K and become antiferromagnetic or ferrimagnetic at lower temperatures. This transition is expressed by a sharp ??-type anomaly in Cpmo for each compound with Ne??el temperatures TN of (92.2??0.2), (43.1??0.2), and (79.45??0.05) K for MnO2, Mn3O4, and Mn2O3, respectively. In addition, at T ??? 308 K, Mn2O3 undergoes a crystallographic transition, from orthorhombic (at low temperatures) to cubic. A significant thermal effect is associated with this change. Hausmanite is ferrimagnetic below TN and in addition to the normal ??-shape of the heat-capacity maxima in MnO2 and Mn2O3, it has a second rounded maximum at 40.5 K. The origin of this subsidiary bump in the heat capacity is unknown but may be related to a similar "anomalous bump" in the curve of magnetization against temperature at about 39 K observed by Dwight and Menyuk.(1) At 298.15 K the standard molar entropies of MnO2, Mn3O4, and Mn2O3, are (52.75??0.07), (164.1??0.2), and (113.7??0.2) J??K-1??mol-1, respectively. Our value for Mn3O4 is greater than that adopted in the National Bureau of Standards tables(2) by 14 per cent. ?? 1985.

XPS and EELS characterization of Mn{sub 2}SiO{sub 4}, MnSiO{sub 3} and MnAl{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Grosvenor, A.P., E-mail: andrew.grosvenor@usask.ca [Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9 (Canada); Bellhouse, E.M., E-mail: erika.bellhouse@arcelormittal.com [Global R & D—Hamilton, ArcelorMittal Dofasco, 1330 Burlington St. E, Hamilton, ON L8N 3J5 (Canada); Korinek, A., E-mail: korinek@mcmaster.ca [Canadian Centre for Electron Microscopy, Brockhouse Institute for Materials Research, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4M1 (Canada); Bugnet, M., E-mail: bugnetm@mcmaster.ca [Canadian Centre for Electron Microscopy, Brockhouse Institute for Materials Research, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4M1 (Canada); McDermid, J.R., E-mail: mcdermid@mcmaster.ca [Steel Research Centre, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4M1 (Canada)

2016-08-30

Graphical abstract: XPS and EELS spectra were acquired from Mn2Al2O4, MnSiO3 and Mn2SiO4 standards and unique features identified that will allow unambiguous identification of these compounds when studying the selective oxidation of advanced steels. - Highlights: • Mn2Al2O4, MnSiO3 and Mn2SiO4 standards were synthesized and characterized using both XPS and EELS. • Unique features in both the XPS high resolution and EELS spectra were identified for all compounds. • The spectra can be used to identify these compounds when studying the selective oxidation of steels. - Abstract: 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 Mn{sub 2}SiO{sub 4}, MnSiO{sub 3}, and MnAl{sub 2}O{sub 4} 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 Mn{sub 2}SiO{sub 4}, MnSiO{sub 3} and MnAl{sub 2}O{sub 4} were synthesized and characterized by XPS and EELS. The unique features of the XPS and EELS spectra for the Mn{sub 2}SiO{sub 4}, MnSiO{sub 3} and MnAl{sub 2}O{sub 4} 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.

Synthesis of Li-Mn-O mesocrystals with controlled crystal phases through topotactic transformation of MnCO₃.

Science.gov (United States)

Dang, Feng; Hoshino, Tatsuhiko; Oaki, Yuya; Hosono, Eiji; Zhou, Haoshen; Imai, Hiroaki

2013-03-21

Mesocrystals of Li-Mn-O compounds, such as LiMn2O4, Li2MnO3, and LiMnO2-Li2MnO3, consisting of oriented nanoscale units were selectively produced under hydrothermal conditions from biomimetically prepared MnCO3 mesocrystals. Topotactic transformation through the intermediate phase of Mn5O8 inheriting a hierarchical structure of the MnCO3 precursor was essential for the formation of the mesocrystal compounds. The crystal phases were successfully controlled by varying the conditions for the hydrothermal reactions. The Li-Mn-O mesocrystals have considerable potential as cathodes of Li-ion batteries.

Laying the Groundwork: Lessons Learned from the Telecommunications Industry for Distributed Generation; Preprint

Energy Technology Data Exchange (ETDEWEB)

Wise, A. L.

2008-05-01

The telecommunications industry went through growing pains in the past that hold some interesting lessons for the growing distributed generation (DG) industry. The technology shifts and stakeholders involved with the historic market transformation of the telecommunications sector mirror similar factors involved in distributed generation today. An examination of these factors may inform best practices when approaching the conduits necessary to accelerate the shifting of our nation's energy system to cleaner forms of generation and use. From a technical perspective, the telecom industry in the 1990s saw a shift from highly centralized systems that had no capacity for adaptation to highly adaptive, distributed network systems. From a management perspective, the industry shifted from small, private-company structures to big, capital-intensive corporations. This presentation will explore potential correlation and outline the lessons that we can take away from this comparison.

Mn induced 1 × 2 reconstruction in the τ-MnAl(0 0 1) surface

Science.gov (United States)

Guerrero-Sánchez, J.; Takeuchi, Noboru

2018-05-01

We report on first principles total energy calculations to describe the structural, electronic and magnetic properties of MnAl(0 0 1) surfaces. We have concentrated in structural models having 1 × 1 and 1 × 2 periodicities, since recent experiments of the similar MnGa(0 0 1) surface have found 1 × 1 and 1 × 2 reconstructions. Our calculations show the existence of two stable structures for different ranges of chemical potential. A 1 × 1 surface is stable for Al-rich conditions, whereas a Mn-induced 1 × 2 reconstruction appears after increasing the Mn chemical potential up to Mn-rich conditions. It is important to notice that experimentally, Mn rich conditions are important for improved magnetic properties. The Mn layers in both structures have ferromagnetic arrangements, but they are aligned antiferromagnetically with the almost no magnetic Al atoms. Moreover, the on top Mn atoms, which produce the 1 × 2 reconstruction, align antiferromagnetically with the second layer Mn atoms. These findings are similar to those obtained experimentally in MnGa thin films grown by molecular beam epitaxy. Therefore, this method could also be used to grow the proposed MnAl films.

Synthesis of Li-Mn-O mesocrystals with controlled crystal phases through topotactic transformation of MnCO3

Science.gov (United States)

Dang, Feng; Hoshino, Tatsuhiko; Oaki, Yuya; Hosono, Eiji; Zhou, Haoshen; Imai, Hiroaki

2013-02-01

Mesocrystals of Li-Mn-O compounds, such as LiMn2O4, Li2MnO3, and LiMnO2-Li2MnO3, consisting of oriented nanoscale units were selectively produced under hydrothermal conditions from biomimetically prepared MnCO3 mesocrystals. Topotactic transformation through the intermediate phase of Mn5O8 inheriting a hierarchical structure of the MnCO3 precursor was essential for the formation of the mesocrystal compounds. The crystal phases were successfully controlled by varying the conditions for the hydrothermal reactions. The Li-Mn-O mesocrystals have considerable potential as cathodes of Li-ion batteries.Mesocrystals of Li-Mn-O compounds, such as LiMn2O4, Li2MnO3, and LiMnO2-Li2MnO3, consisting of oriented nanoscale units were selectively produced under hydrothermal conditions from biomimetically prepared MnCO3 mesocrystals. Topotactic transformation through the intermediate phase of Mn5O8 inheriting a hierarchical structure of the MnCO3 precursor was essential for the formation of the mesocrystal compounds. The crystal phases were successfully controlled by varying the conditions for the hydrothermal reactions. The Li-Mn-O mesocrystals have considerable potential as cathodes of Li-ion batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr33767g

Impurity model for mixed-valent Mn3+/Mn4+ ions

International Nuclear Information System (INIS)

Schlottmann, P.; Lee, K.

1997-01-01

Intermediate valent tri- and tetravalent manganese ions play an important role in LaMnO 3 -based systems. We consider a Mn impurity with five orbitals in cubic symmetry which hybridize with conduction electrons. The exchange interaction in the d shell maximizes the impurity spin. We study the valence of the Mn impurity as a function of the splitting of the e g to t 2g orbitals in zero magnetic field and for the totally spin-polarized state. The lifting of the degeneracy of the e g levels due to a small quadrupolar field, related to the Mn-O bond length or a Jahn-Teller effect, is also investigated. Possible implications on the magnetoresistance are discussed. copyright 1997 The American Physical Society

The Submillimeter Spectrum of MnH and MnD (X7Σ+)

Science.gov (United States)

Halfen, D. T.; Ziurys, L. M.

2008-01-01

The submillimeter-wave spectrum of the MnH and MnD radicals in their 7Σ+ ground states has been measured in the laboratory using direct absorption techniques. These species were created in the gas phase by the reaction of manganese vapor, produced in a Broida-type oven, with either H2 or D2 gas in the presence of a DC discharge. The N = 0 → 1 transition of MnH near 339 GHz was recorded, which consisted of multiple hyperfine components arising from both the manganese and hydrogen nuclear spins. The N = 2 → 3 transition of MnD near 517 GHz was measured as well, but in this case only the manganese hyperfine interactions were resolved. Both data sets were analyzed with a Hund's case b Hamiltonian, and rotational, fine structure, magnetic hyperfine, and electric quadrupole constants have been determined for the two manganese species. An examination of the magnetic hyperfine constants shows that MnH is primarily an ionic species, but has more covalent character than MnF. MnH is a good candidate species for astronomical searches with Herschel, particularly toward material associated with luminous blue variable stars.

Lessons learned in wake of WPPSS

International Nuclear Information System (INIS)

Koenen, A.V.; Gillespie, J.W.

1984-01-01

Several fundamentals of public power financial management have become more critical in the wake of the Washington Public Power Supply System (WPPSS) default: the human and financial costs of trying to resolve problems of this complexity after they occur will require an almost unimaginable amount of time and money that could be productively employed elsewhere; the economic feasibility of the project is paramount, and is far more important than its legal security or its attractiveness to utility managers; the ratepayers' ability and willingness to pay is the key security in public power financing; management performance, not promises, will be the measure of the post WPPSS marketplace; financial flexibility is crucial. Using these lessons, the author outlines a five-step program of strategic planning for planning and managing long-term projects

Revision of the AESJ Standard for Seismic Probabilistic Risk Assessment (PRA). Updating requirements based on the lessons learned from the Fukushima Dai-ichi NPP Accidents (3). Fragility evaluation and outline of the updated points

International Nuclear Information System (INIS)

Yamaguchi, Akira; Nakamura, Susumu; Mihara, Yoshinori

2014-01-01

Lessons learned from Great East Japan earthquake and other new findings had been accumulated on the fragility evaluation of buildings and components. And also new analysis and evaluation method had been proposed with the advancement of recent analysis and evaluation technology. These were reflected in revision of the AESJ Standard for Seismic Probabilistic Risk Assessment (PRA). Scope of the fragility evaluation were extended to all equipment on the site, severe accident management equipment including portable equipment and earthquake concomitant incident (such as tsunami) countermeasure equipment. This article described outlines of updating points of the fragility evaluation of the AESJ Standard for Seismic PRA; (1) requirements for seismic induced other risk evaluations such as fire, inundation and tsunami, (2) simulation technology based on recent findings such as three dimensional responses of buildings / structures and its effect on equipment, (3) requirements of the fragility evaluation for various failure mode of several equipment such as severe accident management equipment, fine failure mode of buildings / structures, failures of equipment related with earthquake concomitant incidents (embankment and seawall) and spent fuel pool, and (4) requirements for the fragility evaluation of aftershocks and soil deformation due to fault displacement. (T. Tanaka)

Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content

DEFF Research Database (Denmark)

Sadowski, Janusz; Domagala, Jaroslaw Z.; Mathieu, Roland

2011-01-01

°C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1% and 2%, grown by molecular beam epitaxy at 270°C. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400°C for layers with initial Mn content of 1% and 2%. Both cubic and hexagonal (Mn......,Ga)As nanocrystals, with similar diameters of 7-10 nm, are observed to coexist in layers with an initial Mn content of 0.5% and 2% after higher-temperature annealing. Measurements of magnetization relaxation in the time span 0.1-10 000 s provide evidence for superparamagnetic properties of the (Mn,Ga)As nanocrystals......X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by moderate-temperature (400°C) and high-temperature (560°C and 630...

9 CFR 114.9 - Outline of Production guidelines.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Outline of Production guidelines. 114.9 Section 114.9 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT... REQUIREMENTS FOR BIOLOGICAL PRODUCTS § 114.9 Outline of Production guidelines. Each Outline of Production shall...

INIR mission Outline, Experiences, Lessons Learned

International Nuclear Information System (INIS)

Omoto, Akira

2010-01-01

There are 19 major issues to consider in infrastructure building and Conditions to achieve the milestone. For each issues that assist in a continuous self-assessment against milestone and there is need to identify the distance to the milestone (gap).The IAEA ‘s involvement could add values to a) objective view b) clarifying areas of further assistance and c) help confidence building, if disclosed. Integrated Nuclear Infrastructure Review (INIR) mission is not an audit against established requirements and its Results cannot be considered as a “release stamp” that certifies the quality and completeness of the work done and validates the host MS actions. INIR mission is conducted in the context of TC programme that Provide feedback on the effective implementation of TC assistance and are considered when preparing and updating the TC Country Programme Framework. It must not be interpreted that the country cannot move to the next phase of the nuclear power programme until all turns to “No actions needed” status, since there is no single uniform avenue for development of infrastructure and launching nuclear power programme

Transition probabilities and dissociation energies of MnH and MnD molecules

International Nuclear Information System (INIS)

Nagarajan, K.; Rajamanickam, N.

1997-01-01

The Frank-Condon factors (vibrational transition probabilities) and r-centroids have been evaluated by the more reliable numerical integration procedure for the bands of A-X system of MnH and MnD molecules, using a suitable potential. By fitting the Hulburt- Hirschfelder function to the experimental potential curve using correlation coefficient, the dissociation energy for the electronic ground states of MnH and MnD molecules, respectively have been estimated as D 0 0 =251±5 KJ.mol -1 and D 0 0 =312±6 KJ.mol -1 . (authors)

More than Solfège and Hand Signs: Philosophy, Tools, and Lesson Planning in the Authentic Kodály Classroom

Science.gov (United States)

Bowyer, James

2015-01-01

Four components of the Kodály concept are delineated here: philosophy, objectives, essential tools, and lesson planning process. After outlining the tenets of the Kodály philosophy and objectives, the article presents the Kodály concept's essential tools, including singing, movable "do" solfège, rhythm syllables, hand signs, singing on…

Lessons learned bulletin

International Nuclear Information System (INIS)

1994-05-01

During the past four years, the Department of Energy -- Savannah River Operations Office and the Westinghouse Savannah River Company (WSRC) Environmental Restoration (ER) Program completed various activities ranging from waste site investigations to closure and post closure projects. Critiques for lessons learned regarding project activities are performed at the completion of each project milestone, and this critique interval allows for frequent recognition of lessons learned. In addition to project related lessons learned, ER also performs lessons learned critiques. T'he Savannah River Site (SRS) also obtains lessons learned information from general industry, commercial nuclear industry, naval nuclear programs, and other DOE sites within the complex. Procedures are approved to administer the lessons learned program, and a database is available to catalog applicable lessons learned regarding environmental remediation, restoration, and administrative activities. ER will continue to use this database as a source of information available to SRS personnel

Correlation of Mn charge state with the electrical resistivity of Mn doped indium tin oxide thin films

KAUST Repository

Kumar, S. R. Sarath

2010-09-15

Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ∼5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ∼4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase.

Correlation of Mn charge state with the electrical resistivity of Mn doped indium tin oxide thin films

KAUST Repository

Kumar, S. R. Sarath; Hedhili, Mohamed N.; Alshareef, Husam N.; Kasiviswanathan, S.

2010-01-01

Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ∼5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ∼4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase.

Enhanced Cycleability of Amorphous MnO₂ by Covering on α-MnO₂ Needles in an Electrochemical Capacitor.

Science.gov (United States)

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.

Five Years after the Fukushima Daiichi Accident: Nuclear Safety Improvements and Lessons Learnt

International Nuclear Information System (INIS)

Magwood, William D. IV; Niel, Jean-Christophe; Fuketa, Toyoshi; Sheron, Brian; Boyd, Michael; McGarry, Ann; Dussart-Desart, Roland; Reig, Javier; Hah, Yeonhee; Nieh, Ho; Vasquez-Maignan, Ximena; Salgado, Nancy; White, Andrew; Lazo, Edward; Creswell, Len; Leeds, Eric; Gannon-Picot, Cynthia; Griffiths, Janice

2016-01-01

Countries around the world continue to implement safety improvements and corrective actions based on lessons learnt from the 11 March 2011 accident at the Fukushima Daiichi nuclear power plant. This report provides a high-level summary and update on these activities, and outlines further lessons learnt and challenges identified for future consideration. It focuses on actions taken by NEA committees and NEA member countries, and as such is complementary to reports produced by other international organisations. It is in a spirit of openness and transparency that NEA member countries share this information to illustrate that appropriate actions are being taken to maintain and enhance the level of safety at their nuclear facilities. Nuclear power plants are safer today because of these actions. High-priority follow-on items identified by NEA committees are provided to assist countries in continuously benchmarking and improving their nuclear safety practices. (authors)

Magnetic phase change in Mn-doped ZnSnAs2 thin films depending on Mn concentration

Science.gov (United States)

Uchitomi, Naotaka; Hidaka, Shiro; Saito, Shin; Asubar, Joel T.; Toyota, Hideyuki

2018-04-01

The relationship between Mn concentration and Curie temperature (TC) is studied for Mn-doped ZnSnAs2 ferromagnetic semiconductors, epitaxially grown on InP substrates by molecular beam epitaxy. In the ferromagnetic phase, Mn distributions in a (Zn,Mn,Sn)As2 thin film with 7.2 cation percent (cat. %) Mn are investigated using three-dimensional atom probe tomography. The results indicate an inhomogeneous distribution which spreads to a relatively high Mn concentration of 9.0 at. % (at. %). In the paramagnetic phase, it is found that the paramagnetic to ferromagnetic transition takes place sharply with a TC of 334 K when the Mn doping concentration increases to about 4 cat. % Mn, which corresponds to a magnetic percolation threshold for ferromagnetism in (Zn,Mn,Sn)As2. An effective Curie temperature ⟨TC⟩ is considered to bridge the Curie temperatures obtained experimentally to those calculated theoretically in inhomogeneous magnetic semiconductors. The behavior of magnetism in Mn-doped ZnSnAs2 can be explained by three different phases within the present framework.

Blended learning: strengths, challenges, and lessons learned in an interprofessional training program.

Science.gov (United States)

Lotrecchiano, G R; McDonald, P L; Lyons, L; Long, T; Zajicek-Farber, M

2013-11-01

This field report outlines the goals of providing a blended learning model for an interdisciplinary training program for healthcare professionals who care for children with disabilities. The curriculum blended traditional face-to-face or on-site learning with integrated online interactive instruction. Credit earning and audited graduate level online coursework, community engagement experiences, and on-site training with maternal and child health community engagement opportunities were blended into a cohesive program. The training approach emphasized adult learning principles in different environmental contexts integrating multiple components of the Leadership Education in Neurodevelopmental and Related Disabilities Program. This paper describes the key principles adopted for this blended approach and the accomplishments, challenges, and lessons learned. The discussion offers examples from training content, material gathered through yearly program evaluation, as well as university course evaluations. The lessons learned consider the process and the implications for the role of blended learning in this type of training program with suggestions for future development and adoption by other programs.

A hierarchical nanostructure consisting of amorphous MnO{sub 2}, Mn{sub 3}O{sub 4} nanocrystallites, and single-crystalline MnOOH nanowires for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Hu, Chi-Chang; Hung, Ching-Yun [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu 30013 (China); Chang, Kuo-Hsin [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu 30013 (China); Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Yang, Yi-Lin [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China)

2011-01-15

In this communication, a porous hierarchical nanostructure consisting of amorphous MnO{sub 2} (a-MnO{sub 2}), Mn{sub 3}O{sub 4} nanocrystals, and single-crystalline MnOOH nanowires is designed for the supercapacitor application, which is prepared by a simple two-step electrochemical deposition process. Because of the gradual co-transformation of Mn{sub 3}O{sub 4} nanocrystals and a-MnO{sub 2} nanorods into an amorphous manganese oxide, the cycle stability of a-MnO{sub 2} is obviously enhanced by adding Mn{sub 3}O{sub 4}. This unique ternary oxide nanocomposite with 100-cycle CV activation exhibits excellent capacitive performances, i.e., excellent reversibility, high specific capacitances (470 F g{sup -1} in CaCl{sub 2}), high power property, and outstanding cycle stability. The highly porous microstructures of this composite before and after the 10,000-cycle CV test are examined by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). (author)

Novel detached system to MnCO3 nanowires: A self-sacrificing template for homomorphous Mn3O4 and α-Mn2O3 nanostructures

International Nuclear Information System (INIS)

Lei Shuijin; Peng Xiaomin; Li Xiuping; Liang Zhihong; Yang Yi; Cheng Baochang; Xiao Yanhe; Zhou Lang

2011-01-01

Research highlights: → A novel detached system along with solvothermal treatment was developed. → Radially aggregated MnCO 3 nanowires were successfully fabricated. → The detached system, solvent, surfactant and reaction time were important. → MnCO 3 nanowires could act as the self-sacrificing template for Mn 3 O 4 and α-Mn 2 O 3 . - Abstract: MnCO 3 , an important raw material, exhibits attractive properties and significant industrial applications. However, few concerns have been raised on the fabrication of its 1D nanostructures. In this paper, a novel detached system was successfully employed for the preparation of MnCO 3 nanowires by a surfactant-assisted solvothermal treatment using N,N-dimethylformamide as the solvent and cetyltrimethylammonium bromide as the surfactant. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were employed to study the crystal structure and morphologies of the products. Experiments showed that the detached system, solvent, surfactant and reaction time were critical for the formation of the MnCO 3 nanowires. The thermal characterization was studied by differential scanning calorimetric analysis and thermogravimetric analysis measurements. The experimental results demonstrated that the as-prepared MnCO 3 nanocrystals can act as an efficient precursor for production of homomorphous Mn 3 O 4 and α-Mn 2 O 3 nanostructures by calcination at 400 deg. C under the atmosphere of argon and air, respectively. A possible growth mechanism for the MnCO 3 nanowires was also proposed.

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

KAUST Repository

Wu, B. L.

2013-10-10

Effect of antiferromagnet on superconductivity has been investigated in IrMn/Nb bilayers. Significant suppression of both transition temperature (Tc) and lower critical field (Hc1) of Nb is found in IrMn/Nb bilayers as compared to a single layer Nb of same thickness; the suppression effect is even stronger than that of a ferromagnet in NiFe/Nb bilayers. The addition of an insulating MgO layer at the IrMn-Nb interface nearly restores Tc to that of the single layer Nb, but Hc1 still remains suppressed. These results suggest that, in addition to proximity effect and magnetic impurity scattering, magnetostatic interaction also plays a role in suppressing superconductivity of Nb in IrMn/Nb bilayers. In addition to reduced Tc and Hc1, the IrMn layer also induces broadening in the transition temperature of Nb, which can be accounted for by a finite distribution of stray field from IrMn.

Ionic Strength-Controlled Mn (Hydr)oxide Nanoparticle Nucleation on Quartz: Effect of Aqueous Mn(OH)2.

Science.gov (United States)

Jung, Haesung; Jun, Young-Shin

2016-01-05

The early formation of manganese (hydr)oxide nanoparticles at mineral-water interfaces is crucial in understanding how Mn oxides control the fate and transport of heavy metals and the cycling of nutrients. Using atomic force microscopy, we investigated the heterogeneous nucleation and growth of Mn (hydr)oxide under varied ionic strengths (IS; 1-100 mM NaNO3). Experimental conditions (i.e., 0.1 mM Mn(2+) (aq) concentration and pH 10.1) were chosen to be relevant to Mn remediation sites. We found that IS controls Mn(OH)2 (aq) formation, and that the controlled Mn(OH)2 (aq) formation can affect the system's saturation and subsequent Mn(OH)2 (s) and further Mn3O4 (s) nanoparticle formation. In 100 mM IS system, nucleated Mn (hydr)oxide particles had more coverage on the quartz substrate than those in 1 mM and 10 mM IS systems. This high IS also resulted in low supersaturation ratio and thus favor heterogeneous nucleation, having better structural matching between nucleating Mn (hydr)oxides and quartz. The unique information obtained in this work improves our understanding of Mn (hydr)oxide formation in natural as well as engineered aqueous environments, such as groundwater contaminated by natural leachate and acid mine drainage remediation.

An outline of ANPA

International Nuclear Information System (INIS)

Del Nero, G.

1997-01-01

The activities of the Italian National Agency for Environmental Protection(ANPA) is outlined including the following: the institutive law of ANPA; main tasks of ANPA; structure of ANPA; personnel of ANPA; provisional structure of ANPA; principal nuclear sites in Italy

IAEA TECDOC 055 Outline

Energy Technology Data Exchange (ETDEWEB)

Shull, Doug [Gregg Protection Services, Palm Beach Gardens, FL (United States)

2015-07-13

An outline of suggestions for updating a version of IAEA-TECDOC-1276 is provided. This update will become IAEA-TECDOC-055, titled ''IAEA handbook for designing and implementing physical protection systems for nuclear material and nuclear facilities.''

Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP

Energy Technology Data Exchange (ETDEWEB)

Lamichhane, Tej N.; Taufour, Valentin; Kaluarachchi, Udhara S.; Bud' ko, Sergey L.; Canfield, Paul C. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); The Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011 (United States); Masters, Morgan W. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Parker, David S. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Thimmaiah, Srinivasa [The Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011 (United States)

2016-08-29

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{sub B}/f.u. and 2.1 μ{sub B}/f.u., respectively, at 50 K. The magnetocaloric effect of ZrMnP in terms of entropy change (ΔS) is estimated to be −6.7 kJ m{sup −3} K{sup −1} around 369 K. The easy axis of magnetization 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.

Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP

International Nuclear Information System (INIS)

Lamichhane, Tej N.; Taufour, Valentin; Kaluarachchi, Udhara S.; Bud'ko, Sergey L.; Canfield, Paul C.; Masters, Morgan W.; Parker, David S.; Thimmaiah, Srinivasa

2016-01-01

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 (ΔS) is estimated to be −6.7 kJ m"−"3 K"−"1 around 369 K. The easy axis of magnetization 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.

Enhanced electrochemical performance of LiMn2O4 by constructing a stable Mn2+-rich interface

Science.gov (United States)

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.

Formation of Mn3O4(001) on MnO(001): Surface and interface structural stability

International Nuclear Information System (INIS)

Bayer, Veronika; Podloucky, Raimund; Franchini, Cesare; Allegretti, Francesco; Xu, Bo; Parteder, Georg; Ramsey, Michael G.; Surnev, Svetlozar; Netzer, Falko P.

2007-01-01

X-ray absorption and photoemission spectroscopies, high-resolution electron energy loss spectroscopy, spot profile analysis low energy electron diffraction, and density functional theory calculations are employed to study the growth of (001) oriented Mn 3 O 4 surfaces on a Pd(100)-supported MnO(001) substrate, with the Hausmannite planar lattice constants aligned along the [110] direction of the underlying MnO(001) support. We show that despite the rather large lattice mismatch, abrupt interfaces may exist between rocksalt MnO and Hausmannite. We argue that this process is facilitated by the relatively low computed strain energy and we propose realistic models for the interface. An atop site registry between the Mn(O) atoms of the oxygen rich Mn 3 O 4 termination and the MnO(001) O(Mn) atoms underneath is found to be the energetically most favorable configuration. The significant planar expansion is accompanied by a large compression of the Mn 3 O 4 vertical lattice constant, yielding structural distortion of the O-Mn-O octahedral axis. Spot profile analysis low energy electron diffraction experiments show that the conversion reaction proceeds easily in both directions, thus indicating the reversible redox character of the transition

Mn fraction substitutional site and defects induced magnetism in Mn-implanted 6H-SiC

Energy Technology Data Exchange (ETDEWEB)

Bouziane, K., E-mail: Khalid.bouziane@uir.ac.ma [Pôle Energies Renouvelables et Etudes Pétrolières, Université Internationale de Rabat, 11000 – Salé el Jadida, Technopolis (Morocco); Al Azri, M.; Elzain, M. [Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman); Chérif, S.M. [LSPM (CNRS-UPR 3407), Université Paris, 13-Nord, 99, Avenue Jean Baptiste Clément, 93430 Villetaneuse (France); Mamor, M. [Equipe MSISM, Faculté Poly-Disciplinaire, B.P. 4162 Safi, Université Cadi Ayyad, Marrakech (Morocco); Declémy, A. [Institut P’, CNRS – Université de Poitiers – ENSMA, UPR 3346, SP2MI – Téléport 2, 11 boulevard Marie et Pierre Curie, BP 30179, F-86962 Futuroscope Chasseneuil Cedex (France); Thomé, L. [CSNSM-Orsay, Bât. 108, Université d’Orsay, F-91405 Orsay (France)

2015-05-25

Highlights: • Shallow Mn-implanted 6H-SiC crystal. • Correlation between Mn-substitutional site concentration and magnetism. • Correlation between defects nature surrounding Mn site and magnetism. • Correlation of magnetism in Mn-doped SiC to Mn at Si sites and vacancy-related defect. - Abstract: n-type 6H-SiC (0 0 0 1) single crystal substrates were implanted with three fluences of manganese (Mn{sup +}) ions: 5 × 10{sup 15}, 1 × 10{sup 16} and 5 × 10{sup 16} cm{sup −2} with implantation energy of 80 keV at 365 °C to stimulate dynamic annealing. The samples were characterized using Rutherford backscattering channeling spectroscopy (RBS/C), high-resolution X-ray diffraction technique (HRXRD), and Superconducting Quantum Interference Device (SQUID) techniques. Two main defect regions have been identified using RBS/C spectra fitted with the McChasy code combined to SRIM simulations. Intermediate defects depth region is associated with vacancies (D{sub V}) and deeper defect (D{sub N}) essentially related to the Si and C interstitial defects. The defect concentration and the maximum perpendicular strain exhibit similar increasing trend with the Mn{sup +} fluence. Furthermore, the amount of Mn atoms at Si substitutional sites and the corresponding magnetic moment per Mn atom were found to increase with increasing Mn fluence from 0.7 μ{sub B} to 1.7 μ{sub B} and then collapsing to 0.2 μ{sub B}. Moreover, a strong correlation has been found between the magnetic moment and the combination of both large D{sub V}/D{sub N} ratio and high Mn at Si sites. These results are corroborated by our ab initio calculations considering the most stable configurations showing that besides the amount of Mn substituting Si sites, local vacancy-rich environment is playing a crucial role in enhancing the magnetism.

Momocs: Outline Analysis Using R

Directory of Open Access Journals (Sweden)

Vincent Bonhomme

2014-02-01

Full Text Available We introduce here Momocs, a package intended to ease and popularize modern morphometrics with R, and particularly outline analysis, which aims to extract quantitative variables from shapes. It mostly hinges on the functions published in the book entitled Modern Morphometrics Using R by Claude (2008. From outline extraction from raw data to multivariate analysis, Momocs provides an integrated and convenient toolkit to students and researchers who are, or may become, interested in describing the shape and its variation. The methods implemented so far in Momocs are introduced through a simplistic case study that aims to test if two sets of bottles have different shapes.

Catalytic Oxidation of NO over MnOx–CeO2 and MnOx–TiO2 Catalysts

Directory of Open Access Journals (Sweden)

Xiaolan Zeng

2016-11-01

Full Text Available A series of MnOx–CeO2 and MnOx–TiO2 catalysts were prepared by a homogeneous precipitation method and their catalytic activities for the NO oxidation in the absence or presence of SO2 were evaluated. Results show that the optimal molar ratio of Mn/Ce and Mn/Ti are 0.7 and 0.5, respectively. The MnOx–CeO2 catalyst exhibits higher catalytic activity and better resistance to SO2 poisoning than the MnOx–TiO2 catalyst. On the basis of Brunauer–Emmett–Teller (BET, X-ray diffraction (XRD, and scanning transmission electron microscope with mapping (STEM-mapping analyses, it is seen that the MnOx–CeO2 catalyst possesses higher BET surface area and better dispersion of MnOx over the catalyst than MnOx–TiO2 catalyst. X-ray photoelectron spectroscopy (XPS measurements reveal that MnOx–CeO2 catalyst provides the abundance of Mn3+ and more surface adsorbed oxygen, and SO2 might be preferentially adsorbed to the surface of CeO2 to form sulfate species, which provides a protection of MnOx active sites from being poisoned. In contrast, MnOx active sites over the MnOx–TiO2 catalyst are easily and quickly sulfated, leading to rapid deactivation of the catalyst for NO oxidation. Furthermore, temperature programmed desorption with NO and O2 (NO + O2-TPD and in situ diffuse reflectance infrared transform spectroscopy (in situ DRIFTS characterizations results show that the MnOx–CeO2 catalyst displays much stronger ability to adsorb NOx than the MnOx–TiO2 catalyst, especially after SO2 poisoning.

Advantages and Disadvantages of the Patient-Centered Medical Home: A Critical Analysis and Lessons Learned.

Science.gov (United States)

Budgen, Jacqueline; Cantiello, John

This article provides a detailed examination of the pros and cons associated with patient-centered medical homes (PCMHs). Opinions and findings from those who have studied PCMHs and those who have been directly involved with this type of health care model are outlined. Key lessons from providers are detailed, and critical success factors are highlighted. This synthesized analysis serves to lend evidence to health care managers and providers who are considering implementation of the PCMH model.

Frequency-domain terahertz transmission spectra of Mn3 and Mn12 single-molecule magnets

Science.gov (United States)

Liu, RuiYuan; Zuo, JunWei; Li, YanRong; Zhou, YuRong; Wang, YunPing

2012-07-01

Frequency-domain terahertz transmission spectra of Mn3 and Mn12 single molecule magnets (SMMs) have been measured at different temperatures, and hence the anisotropic parameters D 2 and D 4 of the spin Hamiltonian hat H = D_2 hat S_z^2 + D_4 hat S_z^4 have been calculated. For Mn12 SMM, D 2=-10.9 GHz and D 4=-2.59×10-2 GHz, while for Mn3 SMM, D 2=-22.0 GHz and D 4 can be considered negligible. This suggests Mn3 SMM can be considered as a simpler and more suitable candidate for magnetic quantum tunneling research.

Formation of self-organized Mn3O4 nanoinclusions in LaMnO3 films

Science.gov (United States)

Pomar, Alberto; Konstantinović, Zorica; Bagués, Nuria; Roqueta, Jaume; López-Mir, Laura; Balcells, Lluis; Frontera, Carlos; Mestres, Narcis; Gutiérrez-Llorente, Araceli; Šćepanović, Maja; Lazarević, Nenad; Popović, Zoran; Sandiumenge, Felip; Martínez, Benjamín; Santiso, José

2016-09-01

We present a single-step route to generate ordered nanocomposite thin films of secondary phase inclusions (Mn3O4) in a pristine perovskite matrix (LaMnO3) by taking advantage of the complex phase diagram of manganese oxides. We observed that in samples grown under vacuum growth conditions from a single LaMnO3 stoichiometric target by Pulsed Laser Deposition, the most favourable mechanism to accommodate Mn2+ cations is the spontaneous segregation of self-assembled wedge-like Mn3O4 ferrimagnetic inclusions inside a LaMnO3 matrix that still preserves its orthorhombic structure and its antiferromagnetic bulk-like behaviour. A detailed analysis on the formation of the self-assembled nanocomposite films evidences that Mn3O4 inclusions exhibit an epitaxial relationship with the surrounding matrix that it may be explained in terms of a distorted cubic spinel with slight ( 9º) c-axis tilting. Furthermore, a Ruddlesden-Popper La2MnO4 phase, helping to the stoichiometry balance, has been identified close to the interface with the substrate. We show that ferrimagnetic Mn3O4 columns influence the magnetic and transport properties of the nanocomposite by increasing its coercive field and by creating local areas with enhanced conductivity in the vicinity of the inclusions.

Breathing Life into Engineering: A Lesson Study Life Science Lesson

Science.gov (United States)

Lawrence, Maria; Yang, Li-Ling; Briggs, May; Hession, Alicia; Koussa, Anita; Wagoner, Lisa

2016-01-01

A fifth grade life science lesson was implemented through a lesson study approach in two fifth grade classrooms. The research lesson was designed by a team of four elementary school teachers with the goal of emphasizing engineering practices consistent with the "Next Generation Science Standards" (NGSS) (Achieve Inc. 2013). The fifth…

The influence of Mn species on the SO2 removal of Mn-based activated carbon catalysts

International Nuclear Information System (INIS)

Qu, Yi-Fan; Guo, Jia-Xiu; Chu, Ying-Hao; Sun, Ming-Chao; Yin, Hua-Qiang

2013-01-01

Using Mn(NO 3 ) 2 as precursor, a series of Mn-based activated carbon catalysts were prepared by ultrasound-assisted excessive impregnation method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The influences of Mn species and nitric acid pretreatment on the removal role of SO 2 were investigated. MnO and Mn 3 O 4 coexist in catalysts calcined at 650 and 800 °C and exhibit best SO 2 removal ability, whereas Mn 2 O 3 formed in the catalyst calcined at 500 °C and shows poor activity. After treatment by nitric acid, the C=O of activated carbon support increases and the crystal size of MnO decreases, resulting in the enhancement of the catalytic activity. During reaction process, manganese oxides are gradually transferred into MnO 2 . And this change directly results in a decrease of activity. But the SO 2 removal rate has been maintained in the range of 30–40%, indicating that MnO 2 still has a certain SO 2 removal ability.

Effects of electronic outlining on students' argumentative writing performance

NARCIS (Netherlands)

de Smet, M.R.J.; Broekkamp, H.; Brand-Gruwel, S.; Kirschner, P.A.

2011-01-01

This study examined the effect of electronic outlining on the quality of students' writing products and how outlining affects perceived mental effort during the writing task. Additionally, it was studied how students appropriate and appreciate an outline tool and whether they need explicit

NMR relaxation studies with MnDPDP

International Nuclear Information System (INIS)

Southon, T.E.; Grant, D.; Bjoernerud, A.; Moen, O.M.; Spilling, B.; Martinsen, I.; Refsum, H.

1997-01-01

Purpose: Our studies were designed to compare the efficacy of mangafodipir trisodium (MnDPDP, Teslascan) as a tissue-specific MR agent with that of manganese chloride (MnCl 2 ), to compare the efficacy of different doses and rates of administration of MnDPDP, and to collect the data needed for predicting optimum pulse sequences. Material and Methods: The dose response for the relaxation rates R1 and R2 at 0.47 T, and the manganese (Mn) concentrations in rat liver and in the liver, pancreas, heart and adrenals of pigs was determined for both MnDPDP and MnCl 2 administered i.v. Computer simulations were carried out to model the effects of different tissue Mn concentrations and TR on signal intensities and contrast-to-noise ratios. Results: In rat liver and pig organs both compounds produced a positive dose-response in R1 and tissue Mn concentration, and only small or no response in R2. The Mn concentration in rat liver was positively correlated with R1, regardless of the form in which Mn was given, or the rate of administration. Optimal imaging parametes are therefore expected to be different pre- and post-MnDPDP administration. (orig./AJ)

X-Band Electron Paramagnetic Resonance Comparison of Mononuclear Mn(IV)-oxo and Mn(IV)-hydroxo Complexes and Quantum Chemical Investigation of Mn(IV) Zero-Field Splitting.

Science.gov (United States)

Leto, Domenick F; Massie, Allyssa A; Colmer, Hannah E; Jackson, Timothy A

2016-04-04

X-band electron paramagnetic resonance (EPR) spectroscopy was used to probe the ground-state electronic structures of mononuclear Mn(IV) complexes [Mn(IV)(OH)2(Me2EBC)](2+) and [Mn(IV)(O)(OH)(Me2EBC)](+). These compounds are known to effect C-H bond oxidation reactions by a hydrogen-atom transfer mechanism. They provide an ideal system for comparing Mn(IV)-hydroxo versus Mn(IV)-oxo motifs, as they differ by only a proton. Simulations of 5 K EPR data, along with analysis of variable-temperature EPR signal intensities, allowed for the estimation of ground-state zero-field splitting (ZFS) and (55)Mn hyperfine parameters for both complexes. From this analysis, it was concluded that the Mn(IV)-oxo complex [Mn(IV)(O)(OH)(Me2EBC)](+) has an axial ZFS parameter D (D = +1.2(0.4) cm(-1)) and rhombicity (E/D = 0.22(1)) perturbed relative to the Mn(IV)-hydroxo analogue [Mn(IV)(OH)2(Me2EBC)](2+) (|D| = 0.75(0.25) cm(-1); E/D = 0.15(2)), although the complexes have similar (55)Mn values (a = 7.7 and 7.5 mT, respectively). The ZFS parameters for [Mn(IV)(OH)2(Me2EBC)](2+) were compared with values obtained previously through variable-temperature, variable-field magnetic circular dichroism (VTVH MCD) experiments. While the VTVH MCD analysis can provide a reasonable estimate of the magnitude of D, the E/D values were poorly defined. Using the ZFS parameters reported for these complexes and five other mononuclear Mn(IV) complexes, we employed coupled-perturbed density functional theory (CP-DFT) and complete active space self-consistent field (CASSCF) calculations with second-order n-electron valence-state perturbation theory (NEVPT2) correction, to compare the ability of these two quantum chemical methods for reproducing experimental ZFS parameters for Mn(IV) centers. The CP-DFT approach was found to provide reasonably acceptable values for D, whereas the CASSCF/NEVPT2 method fared worse, considerably overestimating the magnitude of D in several cases. Both methods were poor in

Governance of CO2 markets: Lessons from the EU ETS

International Nuclear Information System (INIS)

Perthuis, Christian de; Trotignon, Raphael

2014-01-01

The European emissions trading scheme (EU ETS) is the centerpiece of Europe's climate policy. The system has been undermined variously by the weakness of its regulation, an undesirable overlap with other public policies and the far-reaching economic and financial crisis that caused the market price of allowances to plunge. This article attempts to identify the conditions for making the coming years of the EU ETS a success. It draws historical lessons from the eight years the scheme has been in operation, and then presents the various interventions by the public authorities currently under discussion in order to revive the market. Finally, the article proposes to draw lessons from monetary policy by outlining what might be the mandate of an Independent Carbon Market Authority, with responsibility for the dynamic management of the supply of allowances, and whose main mission would be to ensure the optimal linkage between the different temporal horizons of the climate strategy. This article could provide important lessons for schemes developing in the rest of the world, especially in South Korea or in China. - Highlights: • History suggest that ex ante expectations tend to overestimate the constraint. • Economic conditions, policy overlaps, and Kyoto credits cause the current weakness. • “Set aside” or “backloading” does not resolve structural issues. • Changing/extending the reduction target is necessary but not sufficient. • An independent authority could ensure the credibility of the constraint over time

Formation of self-organized Mn3O4 nanoinclusions in LaMnO3 films

Directory of Open Access Journals (Sweden)

Alberto Pomar

2016-09-01

Full Text Available We present a single-step route to generate ordered nanocomposite thin films of secondary phase inclusions (Mn3O4 in a pristine perovskite matrix (LaMnO3 by taking advantage of the complex phase diagram of manganese oxides. We observed that in samples grown under vacuum growth conditions from a single LaMnO3 stoichiometric target by Pulsed Laser Deposition, the most favourable mechanism to accommodate Mn2+ cations is the spontaneous segregation of self-assembled wedge-like Mn3O4 ferrimagnetic inclusions inside a LaMnO3 matrix that still preserves its orthorhombic structure and its antiferromagnetic bulk-like behaviour. A detailed analysis on the formation of the self-assembled nanocomposite films evidences that Mn3O4 inclusions exhibit an epitaxial relationship with the surrounding matrix that it may be explained in terms of a distorted cubic spinel with slight (~9º c-axis tilting. Furthermore, a Ruddlesden-Popper La2MnO4 phase, helping to the stoichiometry balance, has been identified close to the interface with the substrate. We show that ferrimagnetic Mn3O4 columns influence the magnetic and transport properties of the nanocomposite by increasing its coercive field and by creating local areas with enhanced conductivity in the vicinity of the inclusions.

The Knitting Lesson.

Science.gov (United States)

Smith, Pamela

1987-01-01

Based on Jean-Francois Millet's 1869 painting, "The Knitting Lesson," this lesson's goal is to introduce students in grades seven through nine to genre (everyday life) painting the nineteenth century. The lesson is also designed to show that some aspects of genre may be timeless. (BSR)

Shape memory effect in Fe-Mn-Ni-Si-C alloys with low Mn contents

Energy Technology Data Exchange (ETDEWEB)

Min, X.H., E-mail: MIN.Xiaohua@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Sawaguchi, T.; Ogawa, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Maruyama, T. [Awaji Materia Co., Ltd. 2-3-13, Kanda ogawamachi, Chiyoda, Tokyo 101-0052 (Japan); Yin, F.X. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsuzaki, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0047 (Japan)

2011-06-15

Highlights: {yields} A class of new Fe-Mn-Ni-Si-C shape memory alloys with low Mn contents has been designed. {yields} A Mn content for the onset of the {alpha}' martensite is less than 13 mass%, and the {epsilon} martensite still exists in the alloy with a 9 mass% Mn. {yields} The shape recovery strain decreases considerably when the Mn content is reduced from 13 to 11 mass%. {yields} The sudden decrease in the shape recovery strain is mainly caused by the formation of {alpha}' martensite. - Abstract: An attempt was made to develop a new Fe-Mn-Si-based shape memory alloy from a Fe-17Mn-6Si-0.3C (mass%) shape memory alloy, which was previously reported to show a superior shape memory effect without any costly training treatment, by lowering its Mn content. The shape memory effect and the phase transformation behavior were investigated for the as-solution treated Fe-(17-2x)Mn-6Si-0.3C-xNi (x = 0, 1, 2, 3, 4) polycrystalline alloys. The shape recovery strain exceeded 2% in the alloys with x = 0-2, which is sufficient for an industrially applicable shape memory effect; however, it suddenly decreased in the alloys between x = 2 and 3 although the significant shape recovery strain still exceeded 1%. In the alloys with x = 3 and 4, X-ray diffraction analysis and transmission electron microscope observation revealed the existence of {alpha}' martensite, which forms at the intersection of the {epsilon} martensite plates and suppresses the crystallographic reversibility of the {gamma} austenite to {epsilon} martensitic transformation.

Investigation on the electrode process of the Mn(II)/Mn(III) couple in redox flow battery

International Nuclear Information System (INIS)

Xue Fangqin; Wang Yongliang; Wang Wenhong; Wang Xindong

2008-01-01

The Mn(II)/Mn(III) couple has been recognized as a potential anode for redox flow batteries to take the place of the V(IV)/V(V) in all-vanadium redox battery (VRB) and the Br 2 /Br - in sodium polysulfide/bromine (PSB) because it has higher standard electrode potential. In this study, the electrochemical behavior of the Mn(II)/Mn(III) couple on carbon felt and spectral pure graphite were investigated by cyclic voltammetry, steady polarization curve, electrochemical impedance spectroscopy, transient potential-step experiment, X-ray diffraction and charge-discharge experiments. Results show that the Mn(III) disproportionation reaction phenomena is obvious on the carbon felt electrode while it is weak on the graphite electrode owing to its fewer active sites. The reaction mechanism on carbon felt was discussed in detail. The reversibility of Mn(II)/Mn(III) is best when the sulfuric acid concentration is 5 M on the graphite electrode. Performance of a RFB employing Mn(II)/Mn(III) couple as anolyte active species and V(III)/V(II) as catholyte ones was evaluated with constant-current charge-discharge tests. The average columbic efficiency is 69.4% and the voltage efficiency is 90.4% at a current density of 20 mA cm -2 . The whole energy efficiency is 62.7% close to that of the all-vanadium battery and the average discharge voltage is about 14% higher than that of an all-vanadium battery. The preliminary exploration shows that the Mn(II)/Mn(III) couple is electrochemically promising for redox flow battery

The history of a lesson

DEFF Research Database (Denmark)

Rasmussen, Mikkel Vedby

2003-01-01

and emphasises the need to study the history of lessons rather than the lessons of history. This approach shows that Munich is the end point of a constitutive history that begins in the failure of the Versailles treaty to create a durable European order following the First World War. The Munich lesson is thus......The article investigates the concept of lessons in IR. By means of a constructivist critique of the 'lessons literature', the article analyses one of the most important of IR lessons: that of Munich. Examining how the Munich lesson came about, the article shows the praxeological nature of lessons...... one element of the lesson of Versailles, which is a praxeology that defines how the West is to make peace, and against whom peace must be defended. The lesson of Versailles has been, at least in part, constitutive of the outbreak of the Cold War, and it continues to define the Western conception...

Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

International Nuclear Information System (INIS)

Garner, F.A.; Brager, H.R.

1986-06-01

Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

Search for CP Violation and Measurement of the Branching Fraction in the Decay mn>0mn>→KS<mn>0mn>KS>0mn>

Energy Technology Data Exchange (ETDEWEB)

Dash, N.; Bahinipati, S.; Bhardwaj, V.; Trabelsi, K.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Aulchenko, V.; Aushev, T.; Ayad, R.; Babu, V.; Badhrees, I.; Bakich, A. M.; Bansal, V.; Barberio, E.; Bhuyan, B.; Biswal, J.; Bobrov, A.; Bondar, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Breibeck, F.; Browder, T. E.; Červenkov, D.; Chang, M. -C.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, K.; Choi, Y.; Cinabro, D.; Di Carlo, S.; Doležal, Z.; Drásal, Z.; Dutta, D.; Eidelman, S.; Epifanov, D.; Farhat, H.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gillard, R.; Goldenzweig, P.; Haba, J.; Hara, T.; Hayasaka, K.; Hayashii, H.; Hedges, M. T.; Hou, W. -S.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, Y.; Jacobs, W. W.; Jaegle, I.; Jeon, H. B.; Jin, Y.; Joffe, D.; Joo, K. K.; Julius, T.; Kahn, J.; Kaliyar, A. B.; Karyan, G.; Katrenko, P.; Kawasaki, T.; Kiesling, C.; Kim, D. Y.; Kim, H. J.; Kim, J. B.; Kim, K. T.; Kim, M. J.; Kim, S. H.; Kim, Y. J.; Kinoshita, K.; Kodyš, P.; Korpar, S.; Kotchetkov, D.; Križan, P.; Krokovny, P.; Kuhr, T.; Kulasiri, R.; Kumar, R.; Kumita, T.; Kuzmin, A.; Kwon, Y. -J.; Lange, J. S.; Lee, I. S.; Li, C. H.; Li, L.; Li, Y.; Li Gioi, L.; Libby, J.; Liventsev, D.; Lubej, M.; Luo, T.; Masuda, M.; Matvienko, D.; Merola, M.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G. B.; Mohanty, S.; Moon, H. K.; Mori, T.; Mussa, R.; Nakano, E.; Nakao, M.; Nanut, T.; Nath, K. J.; Natkaniec, Z.; Nayak, M.; Niiyama, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Okuno, S.; Ono, H.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Pardi, S.; Park, C. -S.; Park, H.; Paul, S.; Pedlar, T. K.; Pesántez, L.; Pestotnik, R.; Piilonen, L. E.; Prasanth, K.; Ritter, M.; Rostomyan, A.; Sahoo, H.; Sakai, Y.; Sandilya, S.; Santelj, L.; Sanuki, T.; Sato, Y.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Schwartz, A. J.; Seino, Y.; Senyo, K.; Sevior, M. E.; Shebalin, V.; Shen, C. P.; Shibata, T. -A.; Shiu, J. -G.; Shwartz, B.; Simon, F.; Sokolov, A.; Solovieva, E.; Starič, M.; Strube, J. F.; Stypula, J.; Sumisawa, K.; Sumiyoshi, T.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Usov, Y.; Van Hulse, C.; Varner, G.; Vorobyev, V.; Vossen, A.; Waheed, E.; Wang, C. H.; Wang, M. -Z.; Wang, P.; Watanabe, M.; Watanabe, Y.; Widmann, E.; Williams, K. M.; Won, E.; Yamashita, Y.; Ye, H.; Yelton, J.; Yook, Y.; Yuan, C. Z.; Yusa, Y.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.; Zhulanov, V.; Zupanc, A.

2017-10-01

We report a study of the decay mn>0mn>→KS<mn>0mn>KS>0mn> using 921 fb^-1 of data collected at or near the Υ(4S) and Υ(5S) resonances with the Belle detector at the KEKB asymmetric energy e⁺e^- collider. The measured time-integrated CP asymmetry is A_CP(mn>0mn>→KS<mn>0mn>KS>0mn>) = (-0.02 ± 1.53 ± 0.02 ± 0.17)%, and the branching fraction is B(mn>0mn>→KS<mn>0mn>KS>0mn>) = (1.321 ± 0.023 ± 0.036 ± 0.044) × 10^-4, where the first uncertainty is statistical, the second is systematic, and the third is due to the normalization mode (mn>0mn>→KS<mn>0mn>π⁰). These results are significantly more precise than previous measurements available for this mode. The A_CP measurement is consistent with the standard model expectation.

Lesson Learning at JPL

Science.gov (United States)

Oberhettinger, David

2011-01-01

A lessons learned system is a hallmark of a mature engineering organization A formal lessons learned process can help assure that valuable lessons get written and published, that they are well-written, and that the essential information is "infused" into institutional practice. Requires high-level institutional commitment, and everyone's participation in gathering, disseminating, and using the lessons

Zn–Mn alloy coatings from acidic chloride bath: Effect of deposition conditions on the Zn–Mn electrodeposition-morphological and structural characterization

Energy Technology Data Exchange (ETDEWEB)

Loukil, N., E-mail: nloukil87@gmail.com; Feki, M.

2017-07-15

Highlights: • Zn-Mn co-deposition from an additives-free chloride bath is possible. • Effect of Mn{sup 2+} ion concentration and current density on Zn-Mn electrodeposition and particularly Mn content into Zn-Mn deposits were investigated. • A dimensionless graph model was used to analyze the effect of Mn{sup 2+} ion concentration as well as the applied potential on Zn-Mn nucleation process. • Effect of current density on the morphology and structure of Zn-Mn alloys deposits. • A transition from crystalline to amorphous structure may occur in the Mn alloy electrodeposits at high current densities. - Abstract: 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 Mn{sup 2+} ions concentration in the electrolytic bath, Mn{sup 2+} 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 Mn{sup 2+} ions concentration on Zn–Mn nucleation process. It was found that the nucleation process is not extremely affected by Mn{sup 2+} concentration. Nevertheless, it significantly depends on the applied potential. Several parameters such as Mn{sup 2+} 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 j{sub imp} and Mn{sup 2+} 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

Local structure in LaMnO3 and CaMnO3 perovskites: A quantitative structural refinement of Mn K-edge XANES data

International Nuclear Information System (INIS)

Monesi, C.; Meneghini, C.; Bardelli, F.; Benfatto, M.; Mobilio, S.; Manju, U.; Sarma, D.D.

2005-01-01

Hole-doped perovskites such as La 1-x Ca x MnO 3 present special magnetic and magnetotransport properties, and it is commonly accepted that the local atomic structure around Mn ions plays a crucial role in determining these peculiar features. Therefore experimental techniques directly probing the local atomic structure, like x-ray absorption spectroscopy (XAS), have been widely exploited to deeply understand the physics of these compounds. Quantitative XAS analysis usually concerns the extended region [extended x-ray absorption fine structure (EXAFS)] of the absorption spectra. The near-edge region [x-ray absorption near-edge spectroscopy (XANES)] of XAS spectra can provide detailed complementary information on the electronic structure and local atomic topology around the absorber. However, the complexity of the XANES analysis usually prevents a quantitative understanding of the data. This work exploits the recently developed MXAN code to achieve a quantitative structural refinement of the Mn K-edge XANES of LaMnO 3 and CaMnO 3 compounds; they are the end compounds of the doped manganite series La x Ca 1-x MnO 3 . The results derived from the EXAFS and XANES analyses are in good agreement, demonstrating that a quantitative picture of the local structure can be obtained from XANES in these crystalline compounds. Moreover, the quantitative XANES analysis provides topological information not directly achievable from EXAFS data analysis. This work demonstrates that combining the analysis of extended and near-edge regions of Mn K-edge XAS spectra could provide a complete and accurate description of Mn local atomic environment in these compounds

Technical basis for the ITER-FEAT outline design. Progress in resolving open design issues from the outline design report

International Nuclear Information System (INIS)

2000-01-01

In this publication the technical basis for the ITER-FEAT outline design is presented. It comprises the Plant Design Specifications, the Safety Principles and Environmental Criteria, the Site Requirements and Site Design Assumptions. The outline of the key features of the ITER-FEAT design includes main physical parameters and assessment, design overview and preliminary safety assessment, cost and schedule

Risk intelligence: How lessons from folktales/fables contribute to the implementation of risk management in banks

Directory of Open Access Journals (Sweden)

Sivave Mashingaidze

2015-10-01

Full Text Available The objective of this article is to outline credit risk in banks and how fables/folktales can provide with life lessons to implement risk management systems that should act as a stop-gate measure. Banking institutions need to show how proactively managing risk becomes a cornerstone to explore opportunities, rather than simply avoiding dynamites. Risk Intelligence gives companies the confidence to harness risk to explore new opportunities. Lessons were provided from folktales/fables from the animal kingdom. The article adopted a literature review methodology and the results were that, for a business to be successful the medicine does not lie in the policies but the therapy lies in the spirit of oneness in the banks from top management down to the shop floor employee in the branch. By working together the banks can afford to curb credit risks.

Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

International Nuclear Information System (INIS)

Sima, M.; Mihut, L.; Vasile, E.; Sima, Ma.; Logofatu, C.

2015-01-01

Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn 2+ ions into the Zn 2+ site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn 2+ ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A 1 (LO) vibrational modes, from 482 and 567 cm −1 to 532 and 580 cm −1 , respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm −1 spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm −1 confirms the insertion of Mn 2+ ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn 2+ ions into Zn 2+ site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm −1 at high Mn concentration • Compensation of the oxygen vacancy at higher Mn concentration in ZnO lattice

Interface characteristics in Co2MnSi/Ag/Co2MnSi trilayer

International Nuclear Information System (INIS)

Li, Yang; Chen, Hong; Wang, Guangzhao; Yuan, Hongkuan

2016-01-01

Highlights: • Inferface DO 3 disorder is most favorable in Co 2 MnSi/Ag/Co 2 MnSi trilayer. • Interface itself and inferface DO 3 disorder destroy the half-metallicity of interface layers. • Magnetoresistance is reduced by the interface itself and interface disorder. • Magnetotransport coefficient is largely reduced by the interface itself and interface disorder. - Abstract: Interface characteristics of Co 2 MnSi/Ag/Co 2 MnSi trilayer have been investigated by means of first-principles. The most likely interface is formed by connecting MnSi-termination to the bridge site between two Ag atoms. As annealed at high temperature, the formation of interface DO 3 disorder is most energetically favorable. The spin polarization is reduced by both the interface itself and interface disorder due to the interface state occurs in the minority-spin gap. As a result, the magneto-resistance ratio has a sharp drop based on the estimation of a simplified modeling.

Magnetic anisotropy in GaMnAs; Magnetische Anisotropie in GaMnAs

Energy Technology Data Exchange (ETDEWEB)

Daeubler, Joachim

2009-07-02

The goal of the present work was the detailed investigation of the impact of parameters like vertical strain, hole concentration, substrate orientation and patterning on the MA in GaMnAs. At first a method is introduced enabling us to determine the MA from angle-dependent magnetotransport measurements. This method was used to analyze the impact of vertical strain {epsilon}{sub zz} on the MA in a series of GaMnAs layers with a Mn content of 5% grown on relaxed InGaAs-templates. While hole concentration and Curie temperature were found to be unaffected by vertical strain, a significant dependence of the MA on {epsilon}{sub zz} was found. The most pronounced dependence was observed for the anisotropy parameter B{sub 2} {sub perpendicular} {sub to}, representing the intrinsic contribution to the MA perpendicular to the layer plane. For this parameter a linear dependence on {epsilon}{sub zz} was found, resulting in a strain-induced transition of the magnetic easy axis with increasing strain from in-plane to out-of-plane at {epsilon}{sub zz} {approx} -0.13%. Post-growth annealing of the samples leads to an outdiffusion and/or regrouping of the highly mobile Mn interstitial donor defects, resulting in an increase in both p and T{sub C}. For the annealed samples, the transition from in-plane to out-of-plane easy axis takes place at {epsilon}{sub zz} {approx} -0.07%. From a comparison of as-grown and annealed samples, B{sub 2} {sub perpendicular} {sub to} was found to be proportional to both p and {epsilon}{sub zz}, B{sub 2} {sub perpendicular} {sub to} {proportional_to} p .{epsilon}{sub zz}. To study the influence of substrate orientation on the magnetic properties of GaMnAs, a series of GaMnAs layers with Mn contents up to 5% was grown on (001)- and (113)A-oriented GaAs substrates. The hole densities and Curie temperatures, determined from magnetotransport measurements, are drastically reduced in the (113)A layers. The differences in the magnetic properties of (113)A- and

Lessons learned in terms of crisis management; Les enseignements en matiere de gestion de crise

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

This document outlines that nobody was prepared to the crisis which occurred after the Chernobyl accident, whether in Russia, Europe or France. In order to illustrate the fact that crisis management has been different from one country to another, the report describes how the crisis has been managed in Norway (which has been quickly reached by fallouts and with a rather high level) and in Switzerland. It comments radioactivity measurements performed in France during spring 1986 by the SCPRI, the CEA and the ISPN. It discusses the lessons drawn in France in terms of emergency situation management regarding the protection of the population, crisis management, and the French post-accidental doctrine. It comments the lessons drawn in eastern European countries, with the cooperative implication of the IRSN. International projects are evoked: the Chernobyl Centre, the French-German Initiative, the European projects (EURANOS, NERIS, FARMING, STRATEGY, MOSES and SAMEN)

Resonant optical alignment and orientation of Mn2+ spins in CdMnTe crystals

Science.gov (United States)

Baryshnikov, K. A.; Langer, L.; Akimov, I. A.; Korenev, V. L.; Kusrayev, Yu. G.; Averkiev, N. S.; Yakovlev, D. R.; Bayer, M.

2015-11-01

We report on spin orientation and alignment of Mn2 + ions in (Cd,Mn)Te diluted magnetic semiconductor crystals using resonant intracenter excitation with circular- and linear-polarized light. The resulting polarized emission of the magnetic ions is observed at low temperatures when the spin relaxation time of the Mn2 + ions is in the order of 1 ms , which considerably exceeds the photoluminescence decay time of 23 μ s . We demonstrate that the experimental data on optical orientation and alignment of Mn2 + ions can be explained using a phenomenological model that is based on the approximation of isolated centers.

Phase equilibria and stability of the B2 phase in the Ni-Mn-Al and Co-Mn-Al systems

International Nuclear Information System (INIS)

Kainuma, R.; Ise, M.; Ishikawa, K.; Ohnuma, I.; Ishida, K.

1998-01-01

The phase equilibria and ordering reactions in the composition region up to 50 at.% Al have been investigated in the Ni-Mn-Al and Co-Mn-Al systems at temperatures in the interval 850-1200 C mainly by the diffusion couple method. The compositions of the γ (A1: fcc-Ni, -Co, γ-Mn), γ' (L1 2 : Ni 3 Al), β (B2: NiAl, CoAl, NiMn), β-Mn (A13: β-Mn type), δ-Mn (A2: bcc-Mn) and ε (A3: hcp-(Mn, Al)) phases in equilibrium and the critical boundaries of the A2/B2 continuous ordering transition in the bcc phase region have been determined. It is shown that in the Mn-rich portion of the ternary systems both continuous and discontinuous A2 to B2 ordering transitions exist. The A2+B2 two-phase region in the isothermal sections has a lenticular shape and exists over a wide temperature range. The phase equilibria between the γ, γ', β, β-Mn, δ-Mn and ε phases are presented and the stability of the ordered bcc aluminides is discussed. (orig.)

The influence of Mn species on the SO{sub 2} removal of Mn-based activated carbon catalysts

Energy Technology Data Exchange (ETDEWEB)

Qu, Yi-Fan [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Guo, Jia-Xiu, E-mail: guojiaxiu@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); National Engineering Technology Research Center for Flue Gas Desulfurization, Chengdu 610065 (China); Chu, Ying-Hao [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); National Engineering Technology Research Center for Flue Gas Desulfurization, Chengdu 610065 (China); Sun, Ming-Chao [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Yin, Hua-Qiang, E-mail: hqyin@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); National Engineering Technology Research Center for Flue Gas Desulfurization, Chengdu 610065 (China)

2013-10-01

Using Mn(NO{sub 3}){sub 2} as precursor, a series of Mn-based activated carbon catalysts were prepared by ultrasound-assisted excessive impregnation method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The influences of Mn species and nitric acid pretreatment on the removal role of SO{sub 2} were investigated. MnO and Mn{sub 3}O{sub 4} coexist in catalysts calcined at 650 and 800 °C and exhibit best SO{sub 2} removal ability, whereas Mn{sub 2}O{sub 3} formed in the catalyst calcined at 500 °C and shows poor activity. After treatment by nitric acid, the C=O of activated carbon support increases and the crystal size of MnO decreases, resulting in the enhancement of the catalytic activity. During reaction process, manganese oxides are gradually transferred into MnO{sub 2}. And this change directly results in a decrease of activity. But the SO{sub 2} removal rate has been maintained in the range of 30–40%, indicating that MnO{sub 2} still has a certain SO{sub 2} removal ability.

Lesson Development for English Learners in Content Area Settings: Key Considerations. Q&A with Sarah Catherine K. Moore, Ph.D. 2016 Educator Effectiveness Webinar Series

Science.gov (United States)

Moore, Sarah Catherine K.

2016-01-01

In this webinar, Dr. Sarah Catherine K. Moore, Program Director at the Center for Applied Linguistics, outlined factors for content area teachers to consider as they design and deliver lessons for mainstream classrooms that include English learner (EL) students. This Q&A addressed the questions participants had for Dr. Moore following the…

Magnetic structures of Er{sub 6}Mn{sub 23} and Dy{sub 6}Mn{sub 23}

Energy Technology Data Exchange (ETDEWEB)

Ouladdiaf, B. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France); Deportes, J. [Laboratoire de Magnetisme L. Neel, C.N.R.S., BP 166, 38042 Grenoble Cedex 9 (France); Rodriguez-Carvajal, J. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)]|[Laboratoire Leon Brillouin (CEA-CNRS), Centre d`Etudes de Saclay, Gif sur Yvette (France)

1995-08-01

The R{sub 6}Mn{sub 23} (R=rare earth) compounds crystallize in the cubic Th{sub 6}Mn{sub 23}-type structure with space group Fm3m. Powder neutron-diffraction experiments were performed on Dy{sub 6}Mn{sub 23} and Er{sub 6}Mn{sub 23}. The magnetic unit cell coincides with the chemical one. The R moments have a ferromagnetic non-collinear arrangement, whereas the Mn moments are parallel to the [1 1 1] direction. The magnetic structures belong to the three-dimensional {Gamma}{sub 5g} irreducible representation of Fm3m associated with the wave vector K=[0 0 0]. The spin configurations in both compounds result from the competition between the R-R, R-Mn magnetic interactions and the crystal electric field on the R ions. (orig.).

Preliminary Experiment on Neutron-Induced Mn Activity in Mn-Cd Solutions

Energy Technology Data Exchange (ETDEWEB)

Broda, E.

1942-07-01

This report was written by E. Broda, J. Gueron and L. Kowarski at the Cavendish Laboratory (Cambridge) in June 1942 and is about a preliminary experiment on neutron-induced Mn activity in Mn-Cd solutions. The description of the experiment and the results can be found also in this report. (nowak)

Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

Energy Technology Data Exchange (ETDEWEB)

Sima, M., E-mail: msima@infim.ro [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Mihut, L. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Vasile, E. [University “Politehnica”of Bucharest, Faculty of Applied Chemistry and Material Science, Department of Oxide Materials and Nanomaterials, No. 1-7 Gh. Polizu Street, 011061 Bucharest (Romania); Sima, Ma.; Logofatu, C. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania)

2015-09-01

Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn{sup 2+} ions into the Zn{sup 2+} site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn{sup 2+} ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A{sub 1} (LO) vibrational modes, from 482 and 567 cm{sup −1} to 532 and 580 cm{sup −1}, respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm{sup −1} spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm{sup −1} confirms the insertion of Mn{sup 2+} ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn{sup 2+} ions into Zn{sup 2+} site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm{sup −1} at high Mn concentration • Compensation of the oxygen vacancy at higher

Switchable Polarization in Mn Embedded Graphene.

Science.gov (United States)

Noor-A-Alam, Mohammad; Ullah, Hamid; Shin, Young-Han

2018-03-14

Graphene, despite its many unique properties, is neither intrinsically polar due to inversion symmetry nor magnetic. However, based on density functional theory, we find that Mn, one of transition metals, embedded in single or double vacancy (Mn@SV and Mn@DV) in a graphene monolayer induces a dipole moment perpendicular to the sheet, which can be switched from up to down by Mn penetration through the graphene. Such switching could be realized by an external stimuli introduced through the tip of a scanning probe microscope, as already utilized in the studies of molecular switches. We estimate the energy barriers for dipole switching, which are found to be 2.60 eV and 0.28 eV for Mn@SV and Mn@DV, respectively. However, by applying biaxial tensile strain, we propose a mechanism for tuning the barrier. We find that 10% biaxial tensile strain, which is already experimentally achievable in graphene-like two-dimensional materials, can significantly reduce the barrier to 0.16 eV in Mn@SV. Moreover, in agreement with previous studies, we find a high magnetic moment of 3 μ B for both Mn@SV and Mn@DV, promising the potential of these structures in spintronics as well as in nanoscale electro-mechanical or memory devices.

Modular and extensible lesson on fiber optics for youths

Science.gov (United States)

Wong, Nicholas H. L.; Tong, Amy S. K.; Posner, Matthew T.; Ravagli, Andrea

2017-08-01

Fiber optics and its application in telecommunications are rarely encountered by students until they reach tertiary education. While some secondary/middle school curricula may include coverage of basic geometrical optics concepts such as reflection and refraction, few if any go further to elaborate on how these eventually relate to global telecommunications. One could say that the science is made accessible for early-stage students, but discussions about applications are often reserved till later stages. In working through a PhD student-led optics educational outreach program called the "Lightwave Roadshow", we have observed, via engagements with young students and the public at school visits and fairs, that many youths (as well as parents) do have a basic appreciation that the internet is somehow based on light signals. However, few know how the two are related, much less how they work. To address this, our team of `ambassadors' in the Lightwave program has designed a self-contained lesson to introduce youths, aged 11 to 18 years, to fiber optics and optical fiber communications, drawing inspiration from various educational resources such as LASER ClassroomTM and the Exploratorium(R). The lesson is modularized into several parts, starting with using light to communicate Morse code, and then going into advanced concepts, such as total internal reflection and multiuser communications based on wavelength-division multiplexing. The latter can be treated as extensions whose inclusion can be tailored based on the youths' educational levels. A feature of this lesson is that it takes amore phenomenological than theoretical approach, and uses materials that are easily obtainable or craftable as well as interesting for youths, including colored gelatin, LED sources, and water as a waveguide. We outline a lesson and pedagogical method which contains hands-on experiments that can be carried out by educators in formal or informal classes, students learning independently, or

Energy levels of 56Mn

DEFF Research Database (Denmark)

Van Assche, P. H. M.; Baader, H. A.; Koch, H. R.

1971-01-01

The low-energy spectrum of the 55Mn(n,γ)56 Mn reaction has been studied with a γ-diffraction spectrometer. These data allowed the construction of a level scheme for 56Mn with two previously unobserved doublets. High-energy γ-transitions to the low-energy states have been measured for different...

University-based user facilities: lessons from Tantalus and Aladdin

International Nuclear Information System (INIS)

Huber, D.L.

1985-01-01

The establishment of university-based user facilities is a relatively new development in the federal funding of research in condensed matter science. Because the Synchrotron Radiation Center (SRC) has been a pioneer user facility, a certain degree of experience, both good and bad, has been acquired in the construction and operation of university-based facilities for synchrotron-related research. The history of SRC is discussed and some of the general lessons learned in the area of advanced planning are outlined. No attempt is made to be either definitive or exhaustive. In the present context, a university-based user facility is understood to be a dedicated facility under direct university control where a majority of the users come from outside the local university community

Foliar Mn accumulation in eastern Australian herbarium specimens: prospecting for 'new' Mn hyperaccumulators and potential applications in taxonomy.

Science.gov (United States)

Fernando, Denise R; Guymer, Gordon; Reeves, Roger D; Woodrow, Ian E; Baker, Alan J; Batianoff, George N

2009-04-01

The analysis of herbarium specimens has previously been used to prospect for 'new' hyperaccumulators, while the use of foliar manganese (Mn) concentrations as a taxonomic tool has been suggested. On the basis of their geographic and taxonomic affiliations to known Mn hyperaccumulators, six eastern Australian genera from the Queensland Herbarium collection were sampled for leaf tissue analyses. ICP-OES was used to measure Mn and other elemental concentrations in 47 species within the genera Austromyrtus, Lenwebbia, Gossia (Myrtaceae), Macadamia (Proteaceae), Maytenus and Denhamia (Celastraceae). The resulting data demonstrated (a) up to seven 'new' Mn hyperaccumulators, mostly tropical rainforest species; (b) that one of these 'new' Mn hyperaccumulators also had notably elevated foliar Ni concentrations; (c) evidence of an interrelationship between foliar Mn and Al uptake among the Macadamias; (d) considerable variability of Mn hyperaccumulation within Gossia; and (e) the possibility that Maytenus cunninghamii may include subspecies. Gossia bamagensis, G. fragrantissima, G. sankowsiorum, G. gonoclada and Maytenus cunninghamii were identified as 'new' Mn hyperaccumulators, while Gossia lucida and G. shepherdii are possible 'new' Mn hyperaccumulators. Of the three Myrtaceae genera examined, Mn hyperaccumulation appears restricted to Gossia, supporting its recent taxonomic revision. In the context of this present investigation and existing information, a reassesment of the general definition of Mn hyperaccumulation may be warranted. Morphological variation of Maytenus cunninghamii at two extremities was consistent with variation in Mn accumulation, indicating two possible 'new' subspecies. Although caution should be exercised in interpreting the data, surveying herbarium specimens by chemical analysis has provided an effective means of assessing foliar Mn accumulation. These findings should be followed up by field studies.

X-ray spectroscopy at the Mn K edge in LaMnO3 : An ab initio study

NARCIS (Netherlands)

Hozoi, L.; Vries, A.H. de; Broer, R.

2001-01-01

We present ab initio quantum chemical embedded cluster calculations of Mn core-valence and d-d transitions in LaMnO3. The results are also important for the analysis of recent x-ray absorption and x-ray scattering experiments at the Mn K edge in LaMnO3. We find that the first two peaks of the

Phenomenological approach to the spin glass state of (Cu-Mn, Ag-Mn, Au-Mn and Au-Fe) alloys at low temperatures

International Nuclear Information System (INIS)

Al-Jalali, Muhammad A.; Kayali, Fawaz A.

2000-01-01

Full text.The spin glass of: (Cu-Mn, Ag-Mn, Au-Mn, Au-Fe) alloys has been extensively studied. The availability of published and assured experimental data on the susceptibility x(T) of this alloys has enabled the design and application of phenomenological approach to the spin glass state of these interesting alloys. The use of and advanced (S.P.S.S) computer software has resulted revealing some important features of the spin glass in these alloys, the most important of which is that the spin glass state do not represent as phase change

Use of MnO2 and MnO2 SiO2 for sorbing of Sr-90 from liquid rad waste

International Nuclear Information System (INIS)

Subiarto; Las, Thamzil; Aan BH, Martin; Utomo, Cahyo Hari

1998-01-01

The synthesis of MnO 2 adsorbent and MnO 2 -SiO 2 composite has been done. MnO 2 synthesis is done by the reaction of KMnO 4 , Mn(NO 3 ) 2 .4H 2 O and Na 2 S 2 O 4 ( MnO 2 -A, MnO 2 -B, and MnO 2 -T ). MnO 2 . SiO 2 is made from KMnO 4 , Na 2 SiO 3 , and H 2 O 2 . The result obtained show the best Sr-90 sorption by MnO 2 -A with Kd = 2085.63 ml/g, by MnO 2 -L with Kd = 755.09 ml/g, and by MnO 2 - SiO 2 composite with Kd = 1466.51 ml/g. From this result, we can conclude that MnO 2 -SiO 2 can be expanded for Sr-90 sorption from liquid radioactive waste. (author)

Mn porphyrin-based SOD mimic, MnTnHex-2-PyP(5+), and non-SOD mimic, MnTBAP(3-), suppressed rat spinal cord ischemia/reperfusion injury via NF-κB pathways.

Science.gov (United States)

Celic, T; Španjol, J; Bobinac, M; Tovmasyan, A; Vukelic, I; Reboucas, J S; Batinic-Haberle, I; Bobinac, D

2014-12-01

Herein we have demonstrated that both superoxide dismutase (SOD) mimic, cationic Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP(5+)), and non-SOD mimic, anionic Mn(III) meso-tetrakis(4-carboxylatophenyl)porphyrin (MnTBAP(3-)), protect against oxidative stress caused by spinal cord ischemia/reperfusion via suppression of nuclear factor kappa B (NF-κB) pro-inflammatory pathways. Earlier reports showed that Mn(III) N-alkylpyridylporphyrins were able to prevent the DNA binding of NF-κB in an aqueous system, whereas MnTBAP(3-) was not. Here, for the first time, in a complex in vivo system-animal model of spinal cord injury-a similar impact of MnTBAP(3-), at a dose identical to that of MnTnHex-2-PyP(5+), was demonstrated in NF-κB downregulation. Rats were treated subcutaneously at 1.5 mg/kg starting at 30 min before ischemia/reperfusion, and then every 12 h afterward for either 48 h or 7 days. The anti-inflammatory effects of both Mn porphyrins (MnPs) were demonstrated in the spinal cord tissue at both 48 h and 7 days. The downregulation of NF-κB, a major pro-inflammatory signaling protein regulating astrocyte activation, was detected and found to correlate well with the suppression of astrogliosis (as glial fibrillary acidic protein) by both MnPs. The markers of oxidative stress, lipid peroxidation and protein carbonyl formation, were significantly reduced by MnPs. The favorable impact of both MnPs on motor neurons (Tarlov score and inclined plane test) was assessed. No major changes in glutathione peroxidase- and SOD-like activities were demonstrated, which implies that none of the MnPs acted as SOD mimic. Increasing amount of data on the reactivity of MnTBAP(3-) with reactive nitrogen species (RNS) (.NO/HNO/ONOO(-)) suggests that RNS/MnTBAP(3-)-driven modification of NF-κB protein cysteines may be involved in its therapeutic effects. This differs from the therapeutic efficacy of MnTnHex-2-PyP(5+) which presumably occurs via reactive

Structural Series in the Ternary A-Mn-As System (A = Alkali Metal): Double-Layer-Type CsMn4As3 and RbMn4As3 and Tunnel-Type KMn4As3.

Science.gov (United States)

Ishida, Junichi; Iimura, Soshi; Hosono, Hideo

2018-04-16

New manganese arsenides CsMn 4 As 3 , RbMn 4 As 3 , and KMn 4 As 3 were synthesized by solid-state reaction. They consist of edge-sharing MnAs 4 tetrahedra, which are a building block similar to those of Fe-based superconductors. CsMn 4 As 3 and RbMn 4 As 3 adopt the KCu 4 S 3 -type structure (tetragonal P4/ mmm space group, No. 123) with a Mn 4 As 3 double layer, while KMn 4 As 3 has the CaFe 4 As 3 -type structure (orthorhombic Pnma space group, No. 62) with a Mn 4 As 3 tunnel framework. The structural change from CsMn 4 As 3 and RbMn 4 As 3 to KMn 4 As 3 as well as the structural trend of the other ternary A-Mn-As (A = alkali metal) and AE-Mn-As (AE = alkaline-earth metal) compounds is understood as a consequence of reduction of the coordination number around the A and AE sites owing to the decrease of the ionic radius from Cs + to Mg 2+ . Electrical resistivity measurements confirm that the three new phases are Mott insulators with band gaps of 0.52 (CsMn 4 As 3 ), 0.43 (RbMn 4 As 3 ), and 0.31 eV (KMn 4 As 3 ). Magnetic and heat capacity measurements revealed that CsMn 4 As 3 and RbMn 4 As 3 are antiferromagnets without apparent phase transitions below 400 K, which is similar to the magnetism of LaMnAsO and BaMn 2 As 2 , while the existence of the ferromagnetic component was indicated in KMn 4 As 3 with a magnetic transition at 179 K.

Study of Mn dissolution from LiMn{sub 2}O{sub 4} spinel electrodes using rotating ring-disk collection experiments

Energy Technology Data Exchange (ETDEWEB)

Wang, Li-Fang; Ou, Chin-Ching; Striebel, Kathryn A.; Chen, Jenn-Shing

2003-07-01

The goal of this research was to measure Mn dissolution from a thin porous spinel LiMn{sub 2}O{sub 4} electrode by rotating ring-disk collection experiments. The amount of Mn dissolution from the spinel LiMn{sub 2}O{sub 4} electrode under various conditions was detected by potential step chronoamperometry. The concentration of dissolved Mn was found to increase with increasing cycle numbers and elevated temperature. The dissolved Mn was not dependent on disk rotation speed, which indicated that the Mn dissolution from the disk was under reaction control. The in situ monitoring of Mn dissolution from the spinel was carried out under various conditions. The ring currents exhibited maxima corresponding to the end-of-charge (EOC) and end-of-discharge (EOD), with the largest peak at EOC. The results suggest that the dissolution of Mn from spinel LiMn{sub 2}O{sub 4} occurs during charge/discharge cycling, especially in a charged state (at >4.1 V) and in a discharged state (at <3.1 V). The largest peak at EOC demonstrated that Mn dissolution took place mainly at the top of charge. At elevated temperatures, the ring cathodic currents were larger due to the increase of Mn dissolution rate.

Mn induced ferromagnetism spin fluctuation enhancement in Sr{sub 2}Ru{sub 1−x}Mn{sub x}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Zheng, Long; Cai, Jinzhu; Xie, Qiyun; Lv, Bin [Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Mao, Z.Q. [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Wu, X.S., E-mail: xswu@nju.edu.cn [Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

2013-09-15

We establish that Sr{sub 2}RuO{sub 4} is extremely close to incommensurate spin density wave instability. With increasing Mn content, the RuO{sub 6} octahedron in the unit cell varies. The octahedron of RuO{sub 6} contracts along c-axis for x<0.20, Mn element mainly showing the +3 chemical valence (Mn{sup 3+}), and it expands along c-axis with further increasing Mn content (x>0.20), and Mn element shows the +4 chemical valence (Mn{sup 4+}). Spin-glass-related ferromagnetism enhancement is observed for x>0.20, which indicates the critical ferromagnetic spin fluctuation due to Mn doping in Sr{sub 2}Ru{sub 1−x}Mn{sub x}O{sub 4}. - Highlights: • The chemical valence of Mn ions changed from Mn{sup 3+} to Mn{sup 4+} with the increase of Mn content. • Spin-glass-related ferromagnetism enhancement behavior is observed. • The electrical resistivity can be fitted using Mott's variable-range hopping model. • The evolution of octahedron with increase of Mn content is given. • The spin fluctuation effect plays an important role in the magnetic property.

Dynamical control of Mn spin-system cooling by photogenerated carriers in a (Zn,Mn)Se/BeTe heterostructure

Science.gov (United States)

Debus, J.; Maksimov, A. A.; Dunker, D.; Yakovlev, D. R.; Tartakovskii, I. I.; Waag, A.; Bayer, M.

2010-08-01

The magnetization dynamics of the Mn spin system in an undoped (Zn,Mn)Se/BeTe type-II quantum well was studied by a time-resolved pump-probe photoluminescence technique. The Mn spin temperature was evaluated from the giant Zeeman shift of the exciton line in an external magnetic field of 3 T. The relaxation dynamics of the Mn spin temperature to the equilibrium temperature of the phonon bath after the pump-laser-pulse heating can be accelerated by the presence of free electrons. These electrons, generated by a control laser pulse, mediate the spin and energy transfer from the Mn spin system to the lattice and bypass the relatively slow direct spin-lattice relaxation of the Mn ions.

Magnetic and electrical properties of epitaxial GeMn

Energy Technology Data Exchange (ETDEWEB)

Ahlers, Stefan

2009-01-15

In this work, GeMn magnetic semiconductors will be investigated. The fabrication of GeMn thin films with Mn contents up to 11.7% was realised with molecular beam epitaxy. At a fabrication temperature of 60 C, the suppression of Mn{sub x}Ge{sub y} phases could reproducibly be obtained. Dislocation free epitaxy of diamond-lattice type GeMn thin films was observed. In all fabrication conditions where Mn{sub x}Ge{sub y} suppression was feasible, an inhomogeneous dispersion of Mn was observed in form of a self-assembly of nanometre sized, Mn rich regions in a Ge rich matrix. Each Mn rich region exhibits ferromagnetic coupling with high Curie temperatures exceeding, in part, room temperature. The local ferromagnetic ordering leads to the formation of large, spatially separated magnetic moments, which induce a superparamagnetic behaviour of the GeMn thin films. At low temperatures {<=} 20 K, remanent behaviour was found to emerge. X-ray absorption experiments revealed a similarity of the Mn incorporation in diamond-lattice type GeMn thin films and in the hexagonal lattice of the intermetallic Mn{sub 5}Ge{sub 3} phase, respectively. These tetrahedra represent building blocks of the Mn{sub 5}Ge{sub 3} unit cell. The incorporation of Mn{sub 5}Ge{sub 3} building blocks was found to be accompanied by local structural disorder. The electrical properties of GeMn thin films were addressed by transport measurements. It was shown that by using a n-type Ge substrate, a pn energy barrier between epilayers and substrate to suppress parallel substrate conduction paths can be introduced. With the pn barrier concept, first results on the magnetotransport behaviour of GeMn thin films were obtained. GeMn was found to be p-type, but of high resistivity. a series of GeMn thin films was fabricated, where intermetallic Mn{sub x}Ge{sub y} phase separation was supported in a controlled manner. Phase separation was found to result in the formation of partially coherent, nanometre sized Mn{sub 5

First-principles analysis of ferroelectric transition in MnSnO3 and MnTiO3 perovskites

Science.gov (United States)

Kang, Sung Gu

2018-06-01

The ferroelectric instabilities of an artificially adopted Pnma structure in low tolerance perovskites have been explored (Kang et al., 2017) [4], where an unstable A-site environment was reported to be the major driving source for the low tolerance perovskites to exhibit ferroelectric instability. This study examined the ferroelectric transition of two magnetic perovskite materials, MnSnO3 and MnTiO3, in Pnma phase. Phase transitions to the Pnma phase at elevated pressures were observed. MnSnO3, which has a lower (larger) tolerance factor (B-site cation radius), showed a higher ferroelectric mode amplitude than MnTiO3. The distribution of the bond length of Mn-O and the mean quadratic elongation (QE) of octahedra (SnO6 or TiO6) were investigated for structural analysis. However, MnTiO3 showed a larger spontaneous polarization than MnSnO3 due to high Born effective charges of titanium. This study is useful because it provides a valuable pathway to the design of promising multiferroic materials.

Mn L2,3-edge X-ray absorption spectroscopic studies on charge-discharge mechanism of Li2MnO3

International Nuclear Information System (INIS)

Kubobuchi, Kei; Mogi, Masato; Imai, Hideto; Ikeno, Hidekazu; Tanaka, Isao; Mizoguchi, Teruyasu

2014-01-01

The redox reaction of Mn in Li 2 MnO 3 was studied by X-ray absorption spectroscopy and ab initio multiplet calculation. Associated with the de-intercalation of Li-ion, small but clear spectral changes were observed in Mn-L 2,3 X-ray absorption near edge structure (XANES). The systematic ab initio multiplet calculations of Mn-L 2,3 XANES revealed that the spectral changes in the experiment could not simply be ascribed to the change of the valency from Mn 4+ to Mn 5+ but can be explained well by the changes of local atomic structures around Mn 4+ due to the Li de-intercalation. Our results suggest that the electronic state of oxygen should change during charging in Li 2 MnO 3

Martensitic transformation and magnetic properties of manganese-rich Ni-Mn-In and Ni-Mn-Sn Heusler alloys; Untersuchung der martensitischen Umwandlung und der magnetischen Eigenschaften Mangan-reicher Ni-Mn-In- und Ni-Mn-Sn-Heusler-Legierungen

Energy Technology Data Exchange (ETDEWEB)

Krenke, T.

2007-06-29

In the present work, the martensitic transition and the magnetic properties of Manganese rich Ni{sub 50}Mn{sub 50-x}Sn{sub x} and Ni{sub 50}Mn{sub 50-y}In{sub y} alloys with 5 at%{<=}x(y){<=}25 at% were investigated. Calorimetry, X-ray and neutron diffraction, magnetization, and strain measurements were performed on polycrystalline samples. It was shown that alloys close to the stoichiometric composition Ni{sub 50}Mn{sub 25}Sn{sub 25} and Ni{sub 50}Mn{sub 25}Sn{sub 25} do not exhibit a structural transition on lowering of the temperature, whereas alloys with x{<=}15 at% Tin and y{<=}16 at% Indium transform martensitically. The structural transition temperatures increase linearly with decreasing Tin or Indium content. The crystal structures of the low temperature martensite are modulated as well as unmodulated. Alloys with compositions close to stoichiometry are dominated by ferromagnetic interactions, whereas those close to the binary composition Ni{sub 50}Mn{sub 50} order antiferromagnetically. Ferromagnetic order and structural instability coexist in a narrow composition range between 13 at%{<=}x{<=}15 at% and 15 at%{<=}x{<=}16 at% for Ni{sub 50}Mn{sub 50-x}Sn{sub x} and Ni{sub 50}Mn{sub 50-y}In{sub y} respectively. As a consequence, interesting magnetoelastic effects are observed. The Ni{sub 50}Mn{sub 34}In{sub 16} alloy shows a magnetic field-induced structural transition, whereby application of an external magnetic field in the martensitic state stabilizes the high temperature L2{sub 1} structure. Evidence for this was given by neutron diffraction experiments in external magnetic fields. Moreover, the structural transition temperatures of this alloy show large magnetic field dependencies. By use of calorimetry, M(T), and strain measurements, changes in M{sub s} up to -11 K/Tesla are observed. Such large values have, until now, not been observed in Heusler alloys. Since during transformation the volume changes reversibly, magnetic field-induced strains of about

N Reactor Lessons Learned workshop

International Nuclear Information System (INIS)

Heaberlin, S.W.

1993-07-01

This report describes a workshop designed to introduce participants to a process, or model, for adapting LWR Safety Standards and Analysis Methods for use on rector designs significantly different than LWR. The focus of the workshop is on the ''Lessons Learned'' from the multi-year experience in the operation of N Reactor and the efforts to adapt the safety standards developed for commercial light water reactors to a graphite moderated, water cooled, channel type reactor. It must be recognized that the objective of the workshop is to introduce the participants to the operation of a non-LWR in a LWR regulatory world. The total scope of this topic would take weeks to provide a through overview. The objective of this workshop is to provide an introduction and hopefully establish a means to develop a longer term dialogue for technical exchange. This report provides outline of the workshop, a proposed schedule of the workshop, and a description of the tasks will be required to achieve successful completion of the project

Line facilities outline

International Nuclear Information System (INIS)

1998-08-01

This book deals with line facilities. The contents of this book are outline line of wire telecommunication ; development of line, classification of section of line and theory of transmission of line, cable line ; structure of line, line of cable in town, line out of town, domestic cable and other lines, Optical communication ; line of optical cable, transmission method, measurement of optical communication and cable of the sea bottom, Equipment of telecommunication line ; telecommunication line facilities and telecommunication of public works, construction of cable line and maintenance and Regulation of line equipment ; regulation on technique, construction and maintenance.

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

KAUST Repository

Wu, B. L.; Yang, Y. M.; Guo, Z. B.; Wu, Y. H.; Qiu, J. J.

2013-01-01

Effect of antiferromagnet on superconductivity has been investigated in IrMn/Nb bilayers. Significant suppression of both transition temperature (Tc) and lower critical field (Hc1) of Nb is found in IrMn/Nb bilayers as compared to a single layer Nb

Foliar Mn accumulation in eastern Australian herbarium specimens: prospecting for ‘new’ Mn hyperaccumulators and potential applications in taxonomy

Science.gov (United States)

Fernando, Denise R.; Guymer, Gordon; Reeves, Roger D.; Woodrow, Ian E.; Baker, Alan J.; Batianoff, George N.

2009-01-01

Background and Aims The analysis of herbarium specimens has previously been used to prospect for ‘new’ hyperaccumulators, while the use of foliar manganese (Mn) concentrations as a taxonomic tool has been suggested. On the basis of their geographic and taxonomic affiliations to known Mn hyperaccumulators, six eastern Australian genera from the Queensland Herbarium collection were sampled for leaf tissue analyses. Methods ICP-OES was used to measure Mn and other elemental concentrations in 47 species within the genera Austromyrtus, Lenwebbia, Gossia (Myrtaceae), Macadamia (Proteaceae), Maytenus and Denhamia (Celastraceae). Key Results The resulting data demonstrated (a) up to seven ‘new’ Mn hyperaccumulators, mostly tropical rainforest species; (b) that one of these ‘new’ Mn hyperaccumulators also had notably elevated foliar Ni concentrations; (c) evidence of an interrelationship between foliar Mn and Al uptake among the Macadamias; (d) considerable variability of Mn hyperaccumulation within Gossia; and (e) the possibility that Maytenus cunninghamii may include subspecies. Conclusions Gossia bamagensis, G. fragrantissima, G. sankowsiorum, G. gonoclada and Maytenus cunninghamii were identified as ‘new’ Mn hyperaccumulators, while Gossia lucida and G. shepherdii are possible ‘new’ Mn hyperaccumulators. Of the three Myrtaceae genera examined, Mn hyperaccumulation appears restricted to Gossia, supporting its recent taxonomic revision. In the context of this present investigation and existing information, a reassesment of the general definition of Mn hyperaccumulation may be warranted. Morphological variation of Maytenus cunninghamii at two extremities was consistent with variation in Mn accumulation, indicating two possible ‘new’ subspecies. Although caution should be exercised in interpreting the data, surveying herbarium specimens by chemical analysis has provided an effective means of assessing foliar Mn accumulation. These findings should be

Effects of dopant ion and Mn valence state in the La1-xAxMnO3 (A=Sr,Ba) colossal magnetoresistance films

International Nuclear Information System (INIS)

Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyung-Ho; Hong, MunPyo; Kwon, Kwang-Ho

2010-01-01

The structural and electrical properties of Mn-based colossal magnetoresistance (CMR) thin films with controlled tolerance factor and Mn ion valance ratio were studied using crystal structure and chemical bonding character analyses. La 0.7 Sr 0.3 MnO 3 , La 0.7 Ba 0.3 MnO 3 , and La 0.82 Ba 0.18 MnO 3 thin films with different contents of divalent cations and Mn 3+ /Mn 4+ ratios were deposited on amorphous SiO 2 /Si substrate by rf magnetron sputtering at a substrate temperature of 350 deg. C. The films showed the same crystalline structure as the pseudocubic structure. The change in the sheet resistance of films was analyzed according to strain state of the unit cell, chemical bonding character of Mn-O, and Mn 3+ /Mn 4+ ratio controlling the Mn 3+ -O 2- -Mn 4+ conducting path. Mn L-edge x-ray absorption spectra revealed that the Mn 3+ /Mn 4+ ratio changed according to different compositions of Sr or Ba and the Mn 2p core level x-ray photoelectron spectra showed that the Mn 2p binding energy was affected by the covalence of the Mn-O bond and Mn 3+ /Mn 4+ ratio. In addition, O K-edge x-ray absorption spectra showed covalently mixed Mn 3d and O 2p states and matched well with the resistivity changes of CMR films. Temperature coefficient of resistance values were obtained at approximately -2.16%/K to -2.46%/K of the CMR films and were correct for infrared sensor applications.

Martensitic transformation and magnetic properties of manganese-rich Ni-Mn-In and Ni-Mn-Sn Heusler alloys

International Nuclear Information System (INIS)

Krenke, T.

2007-01-01

In the present work, the martensitic transition and the magnetic properties of Manganese rich Ni 50 Mn 50-x Sn x and Ni 50 Mn 50-y In y alloys with 5 at%≤x(y)≤25 at% were investigated. Calorimetry, X-ray and neutron diffraction, magnetization, and strain measurements were performed on polycrystalline samples. It was shown that alloys close to the stoichiometric composition Ni 50 Mn 25 Sn 25 and Ni 50 Mn 25 Sn 25 do not exhibit a structural transition on lowering of the temperature, whereas alloys with x≤15 at% Tin and y≤16 at% Indium transform martensitically. The structural transition temperatures increase linearly with decreasing Tin or Indium content. The crystal structures of the low temperature martensite are modulated as well as unmodulated. Alloys with compositions close to stoichiometry are dominated by ferromagnetic interactions, whereas those close to the binary composition Ni 50 Mn 50 order antiferromagnetically. Ferromagnetic order and structural instability coexist in a narrow composition range between 13 at%≤x≤15 at% and 15 at%≤x≤16 at% for Ni 50 Mn 50-x Sn x and Ni 50 Mn 50-y In y respectively. As a consequence, interesting magnetoelastic effects are observed. The Ni 50 Mn 34 In 16 alloy shows a magnetic field-induced structural transition, whereby application of an external magnetic field in the martensitic state stabilizes the high temperature L2 1 structure. Evidence for this was given by neutron diffraction experiments in external magnetic fields. Moreover, the structural transition temperatures of this alloy show large magnetic field dependencies. By use of calorimetry, M(T), and strain measurements, changes in M s up to -11 K/Tesla are observed. Such large values have, until now, not been observed in Heusler alloys. Since during transformation the volume changes reversibly, magnetic field-induced strains of about 0.12 % appear. Additionally, the alloys Ni 50 Mn 35 Sn 15 , Ni 50 Mn 37 Sn 13 , Ni 50 Mn 34 In 16 , Ni 51.5 Mn 33 In

Fate of half-metallicity near interfaces: The case of NiMnSb/MgO and NiMnSi/MgO

KAUST Repository

Zhang, Ruijing

2014-08-27

The electronic and magnetic properties of the interfaces between the half-metallic Heusler alloys NiMnSb, NiMnSi, and MgO have been investigated using first-principles density-functional calculations with projector augmented wave potentials generated in the generalized gradient approximation. In the case of the NiMnSb/MgO (100) interface, the half-metallicity is lost, whereas the MnSb/MgO contact in the NiMnSb/MgO (100) interface maintains a substantial degree of spin polarization at the Fermi level (∼60%). Remarkably, the NiMnSi/MgO (111) interface shows 100% spin polarization at the Fermi level, despite considerable distortions at the interface, as well as rather short Si/O bonds after full structural optimization. This behavior markedly distinguishes NiMnSi/MgO (111) from the corresponding NiMnSb/CdS and NiMnSb/InP interfaces. © 2014 American Chemical Society.

Epitaxy of (Ga,Mn)As; Epitaxie von (Ga,Mn)As

Energy Technology Data Exchange (ETDEWEB)

Utz, Martin

2012-09-14

The focus of this work lies on the enhancement of the magnetic properties of the ferromagnetic semiconductor Gallium manganese arsenide (GaMnAs), which is a basic material for the research in spintronics: It is told, how a high sample reproducibility and a strong control over the growth process can be gained by applying band edge spectroscopy and a special procedure for the material flux calibration. Also the most important methods for the electrical characterization of GaMnAs are discussed in a critical manner by showing that the anomalous Hall Effect contributes significantly to the Hall resistance even at room temperature and that Novak's method for the termination of the Curie-temperature provides correct values for layers with low defect concentration. Furthermore it is reported on the considerable enlargement of the useable parameter space of GaMnAs which was enabled by the enhanced control over the growth process: It was possible to grow layers with a very high Manganese content of 22% and Curie temperatures of 172 K and even once were produced which showed a strong magnetic moment despite an insulating behaviour at low temperatures. A last key aspect is the growth and characterization of ultra-thin GaMnAs layers, giving prospects for gating experiments or experiments on the proximity effect as these layers combine high Curie temperatures with insulating behaviour.

Effects of Mn and Al on the Intragranular Acicular Ferrite Formation in Rare Earth Treated C-Mn Steel

Science.gov (United States)

Song, Mingming; Song, Bo; Yang, Zhanbing; Zhang, Shenghua; Hu, Chunlin

2017-07-01

The influence of Al, Mn and rare earth (RE) on microstructure of C-Mn steel was investigated. The capacities of different RE inclusions to induce intragranular acicular ferrite (AF) formation were compared. Result shows that RE treatment could make C-Mn steel from large amounts of intragranular AF. Al killed is detrimental to the formation of intragranular AF in RE-treated C-Mn steel. An upper bainite structure would replace the AF when Al content increased to 0.027 mass %. The optimal Mn content to form AF is about 0.75-1.31 mass %. The effective RE inclusion which could induce AF nucleation is La2O2S. When patches of MnS are attached on the surface of La2O2S inclusion, AF nucleation capacity of RE-containing inclusion could enlarge obviously. The existence of manganese-depleted zone and low lattice misfit would be the main reason of La-containing inclusion inducing AF nucleation in C-Mn steel.

X-ray absorption near edge spectroscopy at the Mn K-edge in highly homogeneous GaMnN diluted magnetic semiconductors

Energy Technology Data Exchange (ETDEWEB)

Sancho-Juan, O.; Cantarero, A.; Garro, N.; Cros, A. [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Martinez-Criado, G.; Salome, M.; Susini, J. [ESRF, Polygone Scientifique Louis Neel, 6 rue Jules Horowitz, 38000 Grenoble (France); Olguin, D. [Dept. de Fisica, CINVESTAV-IPN, 07300 Mexico D.F. (Mexico); Dhar, S.; Ploog, K. [Paul Drude Institute, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

2006-06-15

We have studied by X-ray absorption spectroscopy the local environment of Mn in highly homogeneous Ga{sub 1-x}Mn{sub x}N (0.06Mn K-edges. In this report, we focus our attention to the X-ray absorption near edge spectroscopy (XANES) results. The comparison of the XANES spectra corresponding to the Ga and Mn edges indicates that Mn is substitutional to Ga in all samples studied. The XANES spectra measured at the Mn absorption edge shows in the near-edge region a double peak and a shoulder below the absorption edge and the main absorption peak after the edge, separated around 15 eV above the pre-edge structure. We have compared the position of the edge with that of MnO (Mn{sup 2+}) and Mn{sub 2}O{sub 3} (Mn{sup 3+}). All samples studied present the same Mn oxidation state, 2{sup +}. In order to interprete the near-edge structure, we have performed ab initio calculations with a 2 x 2 x 1supercell ({proportional_to}6% Mn) using the full potential linear augmented plane wave method as implemented in the Wien2k code. The calculations show the appearance of Mn anti-bonding t{sub 2g} bands, which are responsible for the pre-edge absorption. The shoulder and main absorption peaks are due to transitions from the valence band 1s-states of Mn to the p-contributions of the conduction bands. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Bilaterally symmetric Fourier approximations of the skull outlines of ...

Indian Academy of Sciences (India)

Unknown

These points denotes break in curvature of the outline and their positions can be compared to .... temnospondyl skull outlines by their shape variations. 2. .... their dentition are related to the feeding habits. Future ... pondyl families is not easy.

Resonantly enhanced spin-lattice relaxation of Mn2 + ions in diluted magnetic (Zn,Mn)Se/(Zn,Be)Se quantum wells

Science.gov (United States)

Debus, J.; Ivanov, V. Yu.; Ryabchenko, S. M.; Yakovlev, D. R.; Maksimov, A. A.; Semenov, Yu. G.; Braukmann, D.; Rautert, J.; Löw, U.; Godlewski, M.; Waag, A.; Bayer, M.

2016-05-01

The dynamics of spin-lattice relaxation in the magnetic Mn2 + ion system of (Zn,Mn)Se/(Zn,Be)Se quantum-well structures are studied using optical methods. Pronounced cusps are found in the giant Zeeman shift of the quantum-well exciton photoluminescence at specific magnetic fields below 10 T, when the Mn spin system is heated by photogenerated carriers. The spin-lattice relaxation time of the Mn ions is resonantly accelerated at the cusp magnetic fields. Our theoretical analysis demonstrates that a cusp occurs at a spin-level mixing of single Mn2 + ions and a quick-relaxing cluster of nearest-neighbor Mn ions, which can be described as intrinsic cross-relaxation resonance within the Mn spin system.

System 80+{trademark} standard design incorporates radiation protection lessons learned

Energy Technology Data Exchange (ETDEWEB)

Crom, T.D.; Naugle, C.L. [Duke Engineering & Services, Inc., Charlotte, NC (United States); Turk, R.S. [ABB Combustion Engineering Nuclear Power, Windsor, CT (United States)

1995-03-01

Many lessons have been learned from the current generation of nuclear plants in the area of radiation protection. The following paper will outline how the lessons learned have been incorporated into the design and operational philosophy of the System 80+{trademark} Standard Design currently under development by ABB Combustion Engineering (ABB-CE) with support from Duke Engineering and Services, Inc. and Stone and Webster Engineering Corporation in the Balance-of-Plant design. The System 80+{trademark} Standard Design is a complete nuclear power plant for national and international markets, designed in direct response to utility needs for the 1990`s, and scheduled for Nuclear Regulatory Commission (NRC) Design Certification under the new standardization rule (10 CFR Part 52). System 80+{trademark} is a natural extension of System 80{sup R} technology, an evolutionary change based on proven Nuclear Steam Supply System (NSSS) in operation at Palo Verde in Arizona and under construction at Yonggwang in the Republic of Korea. The System 80+{trademark} Containment and much of the Balance of Plant design is based upon Duke Power Company`s Cherokee Plant, which was partially constructed in the late 1970`s, but, was later canceled (due to rapid declined in electrical load growth). The System 80+{trademark} Standard Design meets the requirements given in the Electric Power Research Institute (EPRI) Advanced Light Water Reactor (ALWR) Requirements Document. One of these requirements is to limit the occupational exposure to 100 person-rem/yr. This paper illustrates how this goal can be achieved through the incorporation of lessons learned, innovative design, and the implementation of a common sense approach to operation and maintenances practices.

Aluminium alleviates manganese toxicity to rice by decreasing root symplastic Mn uptake and reducing availability to shoots of Mn stored in roots.

Science.gov (United States)

Wang, Wei; Zhao, Xue Qiang; Hu, Zhen Min; Shao, Ji Feng; Che, Jing; Chen, Rong Fu; Dong, Xiao Ying; Shen, Ren Fang

2015-08-01

Manganese (Mn) and aluminium (Al) phytotoxicities occur mainly in acid soils. In some plant species, Al alleviates Mn toxicity, but the mechanisms underlying this effect are obscure. Rice (Oryza sativa) seedlings (11 d old) were grown in nutrient solution containing different concentrations of Mn(2+) and Al(3+) in short-term (24 h) and long-term (3 weeks) treatments. Measurements were taken of root symplastic sap, root Mn plaques, cell membrane electrical surface potential and Mn activity, root morphology and plant growth. In the 3-week treatment, addition of Al resulted in increased root and shoot dry weight for plants under toxic levels of Mn. This was associated with decreased Mn concentration in the shoots and increased Mn concentration in the roots. In the 24-h treatment, addition of Al resulted in decreased Mn accumulation in the root symplasts and in the shoots. This was attributed to higher cell membrane surface electrical potential and lower Mn(2+) activity at the cell membrane surface. The increased Mn accumulation in roots from the 3-week treatment was attributed to the formation of Mn plaques, which were probably related to the Al-induced increase in root aerenchyma. The results show that Al alleviated Mn toxicity in rice, and this could be attributed to decreased shoot Mn accumulation resulting from an Al-induced decrease in root symplastic Mn uptake. The decrease in root symplastic Mn uptake resulted from an Al-induced change in cell membrane potential. In addition, Al increased Mn plaques in the roots and changed the binding properties of the cell wall, resulting in accumulation of non-available Mn in roots. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

ITER-FEAT outline design report

International Nuclear Information System (INIS)

2001-01-01

In July 1998 the ITER Parties were unable, for financial reasons, to proceed with construction of the ITER design proposed at that time, to meet the detailed technical objectives and target cost set in 1992. It was therefore decided to investigate options for the design of ITER with reduced technical objectives and with possibly decreased technical margins, whose target construction cost was one half that of the 1998 ITER design, while maintaining the overall programmatic objective. To identify designs that might meet the revised objectives, task forces involving the JCT and Home Teams met during 1998 and 1999 to analyse and compare a range of options for the design of such a device. This led at the end of 1999 to a single configuration for the ITER design with parameters considered to be the most credible consistent with technical limitations and the financial target, yet meeting fully the objectives with appropriate margins. This new design of ITER, called ''ITER-FEAT'', was submitted to the ITER Director to the ITER Parties as the ''ITER-FEAT Outline Design Report'' (ODR) in January 2000, at their meeting in Tokyo. The Parties subsequently conducted their domestic assessments of this report and fed the resulting comments back into the progressing design. The progress on the developing design was reported to the ITER Technical Advisory Committee (TAC) in June 2000 in the report ''Progress in Resolving Open Design Issues from the ODR'' alongside a report on Progress in Technology R and D for ITER. In addition, the progress in the ITER-FEAT Design and Validating R and D was reported to the ITER Parties. The ITER-FEAT design was subsequently approved by the governing body of ITER in Moscow in June 2000 as the basis for the preparation of the Final Design Report, recognising it as a single mature design for ITER consistent with its revised objectives. This volume contains the documents pertinent to the process described above. More detailed technical information

Direct evidence of the existence of Mn3+ ions in MnTiO3

Science.gov (United States)

Maurya, R. K.; Sharma, Priyamedha; Patel, Ashutosh; Bindu, R.

2017-08-01

We investigate the room temperature electronic properties of MnTiO3 synthesised by different preparation conditions. For this purpose, we prepared MnTiO3 under two different cooling rates, one is naturally cooled while the other is quenched in liq.nitrogen. The samples were studied using optical absorbance, photoemission spectroscopy and band structure calculations. We observe significant changes in the structural parameters as a result of quenching. Interestingly, in the parent compound, our combined core level, valence band and optical absorbance studies give evidence of the Mn existence in both 2+ and 3+ states. The fraction of Mn3+ ions has been found to increase on quenching MnTiO3 suggests an increase in oxygen non-stoichiometry. The increase in the fraction of the Mn3+ ions has been manifested a) as slight enhancement in the intensity of the optical absorbance in the visible region. There occurs persistent photo-resistance when the incident light is terminated after shining; b) in the behaviour of the features (close to Fermi level) in the valence band spectra. Hence, the combined analysis of the core level, valence band and optical absorbance spectra suggests that the charge carriers are hole like which further leads to the increase in the electrical conductivity of the quenched sample. The present results provide a recipe to tune the optical absorption in the visible range for its applications in optical sensors, solar cell, etc.

Effect of Ce addition on microstructure of Al20Cu2Mn3 twin phase in an Al–Cu–Mn casting alloy

International Nuclear Information System (INIS)

Chen Zhongwei; Chen Pei; Li Shishun

2012-01-01

Highlights: ► Rare earth element Ce can retard the formation of the Al 20 Cu 2 Mn 3 twin phase in an Al–Cu–Mn casting alloy. ► Patterns of the particles of the Al 20 Cu 2 Mn 3 phase in Al–Cu–Mn free Ce alloy are more diverse. ► The symmetry of neighboring components of twins is characterized by glide reflection and reflection. ► The twins of Al 20 Cu 2 Mn 3 phase can enhance the mechanical properties of the Al–Cu–Mn casting alloys. - Abstract: Effects of Ce addition on microstructure of Al 20 Cu 2 Mn 3 twin phase and mechanical properties of an Al–Cu–Mn casting alloy were investigated by transmission electron microscopy, selected area electron diffraction, high resolution transmission electron microscopy and tensile test. The results show that rare earth element Ce can retard the formation of the Al 20 Cu 2 Mn 3 phase in the Al–Cu–Mn alloy. Compared with the Ce containing alloy, patterns of particles of the Al 20 Cu 2 Mn 3 phase in the Al–Cu–Mn free Ce alloy are more diverse. The symmetry of neighboring components of twins is characterized by glide reflection and reflection. In addition, twins of the Al 20 Cu 2 Mn 3 phase can enhance the mechanical properties of the Al–Cu–Mn alloy.

L1{sub 0} stacked binaries as candidates for hard-magnets. FePt, MnAl and MnGa

Energy Technology Data Exchange (ETDEWEB)

Matsushita, Yu-ichiro [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Department of Applied Physics, The University of Tokyo (Japan); Madjarova, Galia [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University (Bulgaria); Flores-Livas, Jose A. [Department of Physics, Universitaet Basel (Switzerland); Dewhurst, J.K.; Gross, E.K.U. [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Felser, C. [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Sharma, S. [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Department of Physics, Indian Institute of Technology, Roorkee, Uttarkhand (India)

2017-08-15

We present a novel approach for designing new hard magnets by forming stacks of existing binary magnets to enhance the magneto crystalline anisotropy. This is followed by an attempt at reducing the amount of expensive metal in these stacks by replacing it with cheaper metal with similar ionic radius. This strategy is explored using examples of FePt, MnAl and MnGa. In this study a few promising materials are suggested as good candidates for hard magnets: stacked binary FePt{sub 2}MnGa{sub 2} in structure where each magnetic layer is separated by two non-magnetic layers, FePtMnGa and FePtMnAl in hexagonally distorted Heusler structures and FePt{sub 0.5}Ti{sub 0.5}MnAl. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

NMR studies of 55Mn in amorphous CexMn100-x alloys

International Nuclear Information System (INIS)

Niki, H.; Okamura, K.; Yogi, M.; Amakai, Y.; Takano, H.; Murayama, S.; Obi, Y.

2008-01-01

In order to investigate the heavy-fermion like behavior of amorphous alloy Ce x Mn 100-x , the NMR measurements of 55 Mn (I=5/2 ) in Ce 65 Mn 35 have been carried out from 4.2 to 270 K using powdered sample. A broadened NMR spectrum containing five NQR lines split due to NQR interaction is observed. Quadrupole coupling constant 3e 2 Qq/2I(2I-1)h is gradually changed from about 1.8 MHz at 4.2 K to about 1.6 MHz at 270 K. Temperature dependence of the line width is expressed in the Curie-Weiss law with θ p =-10.5K. The value of Knight shift would be almost constant from 4.2 to 270 K

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors

Science.gov (United States)

Xia, Hui; Wang, Yu; Lin, Jianyi; Lu, Li

2012-01-01

MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.

Enabling and sustaining the activities of lay health influencers: lessons from a community-based tobacco cessation intervention study.

Science.gov (United States)

Castañeda, Heide; Nichter, Mark; Nichter, Mimi; Muramoto, Myra

2010-07-01

The authors present findings from a community-based tobacco cessation project that trained lay health influencers to conduct brief interventions. They outline four major lessons regarding sustainability. First, participants were concerned about the impact that promoting cessation might have on social relationships. "Social risk" must be addressed during training to ensure long-term sustainability. Second, formal training provided participants with an increased sense of self-efficacy, allowed them to embrace a health influencer identity, and aided in further reducing social risk. Third, material resources functioned to mediate social tensions during health intervention conversations. A variety of resources should be made available to health influencers to accommodate type of relationship, timing, and location of the interaction. Finally, project design must be attentive to the creation of a "community of practice" among health influencers as an integral part of project sustainability. These lessons have broad implications for successful health promotion beyond tobacco cessation.

Energy transfer between Pr3+ and Mn2+ in K2YZr(PO4)3: Pr, Mn phosphor

International Nuclear Information System (INIS)

Liang Wei; Wang Yuhua

2011-01-01

Research highlights: → Pr 3+ , Mn 2+ co-doped K 2 YZr(PO 4 ) 3 phosphor is a novel type of practical visible quantum cutting phosphor in promising application. → The optimal quantum efficiency (QE) of this co-doped system K 2 YZr(PO 4 ) 3 : Pr 3+ , Mn 2+ reached to 126.3%. → The Mn 2+6 A 1g → 4 E g - 4 A 1g transition was found to coincide well with the 1 S 0 → 1 I 6 transition of Pr 3+ . → The energy transfer from Pr 3+ to Mn 2+ was also observed, converting the first photon from the PCE of Pr 3+ into the red emission of Mn 2+ , and the QC process occurred in this Pr 3+ , Mn 2+ co-doped K 2 YZr(PO 4 ) 3 phosphor. - Abstract: Pr 3+ , Mn 2+ co-doped K 2 YZr(PO 4 ) 3 samples were prepared by solid-state reaction method and their photoluminescence (PL) properties were investigated in ultra-violet (UV) and vacuum ultra-violet (VUV) region. The results indicated that in Pr 3+ singly doped K 2 YZr(PO 4 ) 3 sample, the first-step transition ( 1 S 0 → 1 I 6 , 3 P J around 405 nm) of Pr 3+ is near the ultraviolet (UV) range, not useful for practical application. When Mn 2+ was doped as a co-activator ion, the energy of 1 S 0 → 1 I 6 , 3 P J transition can be transferred synchronously from Pr 3+ to Mn 2+ and then emit a visible photon. The optimal quantum efficiency (QE) of this co-doped system K 2 YZr(PO 4 ) 3 : Pr 3+ , Mn 2+ reached to 126.3%, suggesting a novel type of practical visible quantum cutting phosphor in promising application.

A Lesson about the Circular Flow. Active Learning Lessons. Economics International.

Science.gov (United States)

Landfried, Janet

This lesson plan was developed through "Economics International," an international program to help build economic education infrastructures in the emerging market economies. It provides a lesson description; appropriate grade level; economic concepts; content standards and benchmarks; related subjects; instructional objectives; time…

Cation Effects on the Layer Structure of Biogenic Mn-Oxides

Energy Technology Data Exchange (ETDEWEB)

Zhu, M.; Ginder-Vogel, M; Parikh, S; Feng, X; Sparks, D

2010-01-01

Biologically catalyzed Mn(II) oxidation produces biogenic Mn-oxides (BioMnO{sub x}) and may serve as one of the major formation pathways for layered Mn-oxides in soils and sediments. The structure of Mn octahedral layers in layered Mn-oxides controls its metal sequestration properties, photochemistry, oxidizing ability, and topotactic transformation to tunneled structures. This study investigates the impacts of cations (H{sup +}, Ni(II), Na{sup +}, and Ca{sup 2+}) during biotic Mn(II) oxidation on the structure of Mn octahedral layers of BioMnO{sub x} using solution chemistry and synchrotron X-ray techniques. Results demonstrate that Mn octahedral layer symmetry and composition are sensitive to previous cations during BioMnO{sub x} formation. Specifically, H{sup +} and Ni(II) enhance vacant site formation, whereas Na{sup +} and Ca{sup 2+} favor formation of Mn(III) and its ordered distribution in Mn octahedral layers. This study emphasizes the importance of the abiotic reaction between Mn(II) and BioMnO{sub x} and dependence of the crystal structure of BioMnO{sub x} on solution chemistry.

SciNet: Lessons Learned from Building a Power-efficient Top-20 System and Data Centre

International Nuclear Information System (INIS)

Loken, Chris; Gruner, Daniel; Groer, Leslie; Peltier, Richard; Bunn, Neil; Craig, Michael; Henriques, Teresa; Dempsey, Jillian; Yu, Ching-Hsing; Chen, Joseph; Dursi, L Jonathan; Chong, Jason; Northrup, Scott; Pinto, Jaime; Knecht, Neil; Van Zon, Ramses

2010-01-01

SciNet, one of seven regional HPC consortia operating under the Compute Canada umbrella, runs Canada's first and third fastest computers (as of June 2010) in a state-of-the-art, highly energy-efficient datacentre with a Power Usage Effectiveness (PUE) design-point of 1.16. Power efficiency, computational 'bang for the buck' and system capability for a handful of flagship science projects were important criteria in choosing the nature of the computers and the data centre itself. Here we outline some of the lessons learned in putting together the systems and the data centre that hosts Canada's fastest computer to date.

XANES Studies of Mn K and L3,2 Edges in the (Ga,Mn)As Layers Modified by High Temperature Annealing

International Nuclear Information System (INIS)

Wolska, A.; Lawniczak-Jablonska, K.; Klepka, M.T.; Jakiela, R.; Demchenko, I.N.; Sadowski, J.; Holub-Krappe, E.; Persson, A.; Arvanitis, D.

2008-01-01

Ga 1-x Mn x As is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper Ga 1-x Mn x As samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scattering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not ob- serve changes in the electronic structure of Ga and As introduced by the presence of the Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate the preferred interstitial positions of the Mn atoms. (authors)

Solid state synthesis of Mn{sub 5}Ge{sub 3} in Ge/Ag/Mn trilayers: Structural and magnetic studies

Energy Technology Data Exchange (ETDEWEB)

Myagkov, V.G.; Bykova, L.E.; Matsynin, A.A.; Volochaev, M.N.; Zhigalov, V.S.; Tambasov, I.A. [Kirensky Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Mikhlin, Yu L. [Institute of Chemistry and Chemical Technology, SB RAS, Krasnoyarsk 660049 (Russian Federation); Velikanov, D.A. [Kirensky Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Bondarenko, G.N. [Institute of Chemistry and Chemical Technology, SB RAS, Krasnoyarsk 660049 (Russian Federation)

2017-02-15

The thin-film solid-state reaction between elemental Ge and Mn across chemically inert Ag layers with thicknesses of (0, 0.3, 1 and 2.2 µm) in Ge/Ag/Mn trilayers was studied for the first time. The initial samples were annealed at temperatures between 50 and 500 °C at 50 °C intervals for 1 h. The initiation temperature of the reaction for Ge/Mn (without a Ag barrier layer) was ~ 120 °C and increased slightly up to ~ 250 °C when the Ag barrier layer thickness increased up to 2.2 µm. In spite of the Ag layer, only the ferromagnetic Mn{sub 5}Ge{sub 3} compound and the Nowotny phase were observed in the initial stage of the reaction after annealing at 500 °C. The cross-sectional studies show that during Mn{sub 5}Ge{sub 3} formation the Ge is the sole diffusing species. The magnetic and cross-sectional transmission electron microscopy (TEM) studies show an almost complete transfer of Ge atoms from the Ge film, via a 2.2 µm Ag barrier layer, into the Mn layer. We attribute the driving force of the long-range transfer to the long-range chemical interactions between reacting Mn and Ge atoms. - Graphical abstract: The direct visualization of the solid state reaction between Mn and Ge across a Ag buffer layer at 500 °C. - Highlights: • The migration of Ge, via an inert 2.2 µm Ag barrier, into a Mn layer. • The first Mn{sub 5}Ge{sub 3} phase was observed in reactions with different Ag layers. • The Ge is the sole diffusing species during Mn{sub 5}Ge{sub 3} formation • The long-range chemical interactions control the Ge atomic transfer.

Decay data evaluation project: Evaluation of 52Mn and 52mMn nuclear decay data

Science.gov (United States)

Luca, Aurelian

2017-09-01

All nuclear decay data within the 52Fe-52m,52Mn-52Cr decay chain have been evaluated at IFIN-HH, Romania, as part of an IAEA coordinated research project (F41029) and incorporated into the Decay Data Evaluation Project (DDEP). Both 52Fe and daughter 52Mn are two potentially promising radionuclides to be incorporated into suitable radiopharmaceuticals for PET and SPECT imaging. The decay data evaluation of 52Fe has previously been published and reported to the IAEA Nuclear Data Section. Equivalent DDEP evaluations for 52Mn and 52mMn have also been completed recently, and are presented in summary form below. These improved decay data sets have also been reported to the IAEA in detail, and are highly suitable in dose rate calculations for their application in nuclear medicine.

Atomistic spin dynamics simulations on Mn-doped GaAs and CuMn

Energy Technology Data Exchange (ETDEWEB)

Hellsvik, Johan, E-mail: johan.hellsvik@fysik.uu.s [Department of Physics and Materials Science, Uppsala University, Box 530, SE-751 21 Uppsala (Sweden)

2010-01-01

The magnetic dynamical behavior of two random alloys have been investigated in atomistic spin dynamics (ASD) simulations. For both materials, magnetic exchange parameters calculated with first principles electronic structure methods were used. From experiments it is well known that CuMn is a highly frustrated magnetic system and a good manifestation of a Heisenberg spin glass. In our ASD simulations the behavior of the autocorrelation function indicate spin glass behavior. The diluted magnetic semiconductor (DMS) Mn-doped GaAs is engineered with hopes of high enough Curie temperatures to operate in spintronic devices. Impurities such as As antisites and Mn interstitials change the exhange couplings from being mainly ferromagnetic to also have antiferromagnetic components. We explore how the resulting frustration affects the magnetization dynamics for a varying rate of As antisites.

Theoretical Mn K-edge XANES for Li2MnO3: DFT + U study

International Nuclear Information System (INIS)

Tamura, Tomoyuki; Ohwaki, Tsukuru; Ito, Atsushi; Ohsawa, Yasuhiko; Kobayashi, Ryo; Ogata, Shuji

2012-01-01

Spectral features of Mn K-edge x-ray absorption near-edge structure (XANES) for Li 2 MnO 3 were calculated using the first-principles full projector augmented wave method with the general gradient approximation plus U method. We demonstrated that the U parameter affects the spectral features in the pre-edge region while it does not affect those in the major absorption region. From the comparison with the experimental spectra and those of reference compounds, we showed that the spectral features of Mn K-edge XANES and the differences in the valence state can be reproduced well. (paper)

Benthic foraminiferal Mn / Ca ratios reflect microhabitat preferences

Science.gov (United States)

Koho, Karoliina A.; de Nooijer, Lennart J.; Fontanier, Christophe; Toyofuku, Takashi; Oguri, Kazumasa; Kitazato, Hiroshi; Reichart, Gert-Jan

2017-06-01

The Mn / Ca of calcium carbonate tests of living (rose-Bengal-stained) benthic foraminifera (Elphidium batialis, Uvigerina spp., Bolivina spissa, Nonionellina labradorica and Chilostomellina fimbriata) were determined in relation to pore water manganese (Mn) concentrations for the first time along a bottom water oxygen gradient across the continental slope along the NE Japan margin (western Pacific). The local bottom water oxygen (BWO) gradient differs from previous field study sites focusing on foraminiferal Mn / Ca and redox chemistry, therefore allowing further resolution of previously observed trends. The Mn / Ca ratios were analysed using laser ablation inductively coupled plasma-mass spectrometer (ICP-MS), allowing single-chamber determination of Mn / Ca. The incorporation of Mn into the carbonate tests reflects environmental conditions and is not influenced by ontogeny. The inter-species variability in Mn / Ca reflected foraminiferal in-sediment habitat preferences and associated pore water chemistry but also showed large interspecific differences in Mn partitioning. At each station, Mn / Ca ratios were always lower in the shallow infaunal E. batialis, occupying relatively oxygenated sediments, compared to intermediate infaunal species, Uvigerina spp. and B. spissa, which were typically found at greater depth, under more reducing conditions. The highest Mn / Ca was always recorded by the deep infaunal species N. labradorica and C. fimbriata. Our results suggest that although partitioning differs, Mn / Ca ratios in the intermediate infaunal taxa are promising tools for palaeoceanographic reconstructions as their microhabitat exposes them to higher variability in pore water Mn, thereby making them relatively sensitive recorders of redox conditions and/or bottom water oxygenation.

Classroom Management and Lesson Planning(4)

Institute of Scientific and Technical Information of China (English)

2006-01-01

Lesson PlanningTask 1As teachers,we all need to plan our lessons before we teach.Make a list of things that you think need tobe included in a lesson plan.Then compare and discuss your list with another teacher.Also think about reasonswhy we need to plan our lessons.

Constellation Program Lessons Learned. Volume 2; Detailed Lessons Learned

Science.gov (United States)

Rhatigan, Jennifer; Neubek, Deborah J.; Thomas, L. Dale

2011-01-01

These lessons learned are part of a suite of hardware, software, test results, designs, knowledge base, and documentation that comprises the legacy of the Constellation Program. The context, summary information, and lessons learned are presented in a factual format, as known and described at the time. While our opinions might be discernable in the context, we have avoided all but factually sustainable statements. Statements should not be viewed as being either positive or negative; their value lies in what we did and what we learned that is worthy of passing on. The lessons include both "dos" and "don ts." In many cases, one person s "do" can be viewed as another person s "don t"; therefore, we have attempted to capture both perspectives when applicable and useful. While Volume I summarizes the views of those who managed the program, this Volume II encompasses the views at the working level, describing how the program challenges manifested in day-to-day activities. Here we see themes that were perhaps hinted at, but not completely addressed, in Volume I: unintended consequences of policies that worked well at higher levels but lacked proper implementation at the working level; long-term effects of the "generation gap" in human space flight development, the need to demonstrate early successes at the expense of thorough planning, and the consequences of problems and challenges not yet addressed because other problems and challenges were more immediate or manifest. Not all lessons learned have the benefit of being operationally vetted, since the program was cancelled shortly after Preliminary Design Review. We avoid making statements about operational consequences (with the exception of testing and test flights that did occur), but we do attempt to provide insight into how operational thinking influenced design and testing. The lessons have been formatted with a description, along with supporting information, a succinct statement of the lesson learned, and

Classroom Management and Lesson Planning(4)

Institute of Scientific and Technical Information of China (English)

2006-01-01

@@ Lesson Planning Task 1 As teachers,we all need to plan our lessons before we teach.Make a list of things that you think need to be included in a lesson plan.Then compare and discuss your list with another teacher.Also think about reasons why we need to plan our lessons.

Synthesis of highly efficient Mn2O3 catalysts for CO oxidation derived from Mn-MIL-100

Science.gov (United States)

Zhang, Xiaodong; Li, Hongxin; Hou, Fulin; Yang, Yang; Dong, Han; Liu, Ning; Wang, Yuxin; Cui, Lifeng

2017-07-01

In this work, metal-organic frameworks (MOFs) Mn-MIL-100 were first prepared, which were next used as templates to obtain the irregular porous Mn2O3 cubes through calcination with air at different temperature. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), H2-temperature program reduction (H2-TPR) and X-ray photoelectron spectroscopic (XPS). The catalytic activity for CO oxidation over Mn2O3 catalysts was investigated. It was found that calcination temperature had a strong effect on the structure and catalytic activity of Mn2O3 catalyst. Mn2O3 catalyst obtained by calcined at 700 °C (Mn2O3-700) showed a smaller specific surface area, but displayed a high catalytic activity and excellent stability with a complete CO conversion temperature (T98) of 240 °C, which was attributed to the unique structure, a high quantity of surface active oxygen species, smaller particle size, oxygen vacancies and good low temperature reduction behavior. The effect of water vapor on catalytic activity was also examined. The introduction of water vapor to the feedstock induced a positive effect on CO oxidation over Mn2O3-700 catalyst. Furthermore, no obvious drop is observed in activity over catalysts even in the presence of water vapor during 48 h.

Bilaterally symmetric Fourier approximations of the skull outlines of ...

Indian Academy of Sciences (India)

Present work illustrates a scheme of quantitative description of the shape of the skull outlines of temnospondyl amphibians using bilaterally symmetric closed Fourier curves. Some special points have been identified on the Fourier fits of the skull outlines, which are the local maxima, or minima of the distances from the ...

Theoretical investigation of the reaction of Mn+ with ethylene oxide.

Science.gov (United States)

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.

Participating in and delivering the ATEAM trial (Alexander technique lessons, exercise, and massage) interventions for chronic back pain: A qualitative study of professional perspectives.

Science.gov (United States)

Beattie, Angela; Shaw, Alison; Yardley, Lucy; Little, Paul; Sharp, Debbie

2010-01-01

To outline professionals' experiences of participation, perceived benefits and acceptability of the interventions delivered in the ATEAM trial (Alexander technique lessons, exercise, and massage), for patients with chronic or recurrent back pain. Qualitative study using in-depth interviews was conducted with a purposeful sample of twenty professionals (general practitioners (GPs), nurses, Alexander technique teachers, and massage therapists). Data were recorded, transcribed, and analysed thematically using the constant comparison method. Evidence of effectiveness GPs wanted an evidence base for the interventions, whilst nurses, Alexander technique teachers and massage therapists perceived patient reports of benefit as evidence. Professionals' perception of the acceptability of the intervention: professional perspectives differed, with GPs and nurses viewing the structured nature of exercise prescription and Alexander technique lessons as more beneficial and acceptable than massage in alleviating patients' back pain. Economic cost: the cost to patients pursuing Alexander technique lessons and massage was perceived to be a barrier outside the trial. Inter-professional communication: there was little communication between the professionals groups within the trial. Valuable insights have been gained into the perceived benefits and acceptability of exercise, Alexander technique lessons and massage as interventions for chronic back pain. Lessons in the Alexander technique with or without exercise, was perceived as more beneficial and acceptable than massage by professionals who participated and delivered the ATEAM trial interventions. Copyright 2010 Elsevier Ltd. All rights reserved.

Lesson Planning the Kodaly Way.

Science.gov (United States)

Boshkoff, Ruth

1991-01-01

Discusses the contribution of Zoltan Kodaly to music lesson planning. Emphasizes preparation, presentation, and practice as the three important strategies in teaching concepts and skills to be included in a lesson plan. Includes a sample lesson plan covering a semester and advice on choosing song material. (DK)

Magnetic and electrical properties of several Mn-based amorphous alloys

Science.gov (United States)

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.

Anisotropic magnetic structures of the Mn R MnSbO6 high-pressure doubly ordered perovskites (R =La , Pr, and Nd)

Science.gov (United States)

Solana-Madruga, Elena; Arévalo-López, Ángel M.; Dos santos-García, Antonio J.; Ritter, Clemens; Cascales, Concepción; Sáez-Puche, Regino; Attfield, J. Paul

2018-04-01

A new type of doubly ordered perovskite (also reported as double double perovskite, DDPv) structure combining columnar and rock-salt orders of the cations at the A and B sites, respectively, was recently found at high pressure for Mn R MnSb O6 (R =La -Sm ). Here we report further magnetic structures of these compounds. M n2 + spins align into antiparallel ferromagnetic sublattices along the x axis for MnLaMnSb O6 , while the magnetic anisotropy of P r3 + magnetic moments induces their preferential order along the z direction for MnPrMnSb O6 . The magnetic structure of MnNdMnSb O6 was reported to show a spin-reorientation transition of M n2 + spins from the z axis towards the x axis driven by the ordering of N d3 + magnetic moments. The crystal-field parameters for P r3 + and N d3 + at the 4 e C2 site of their DDPv structure have been semiempirically estimated and used to derive their energy levels and associated wave functions. The results demonstrate that the spin-reorientation transition in MnNdMnSb O6 arises as a consequence of the crystal-field-induced magnetic anisotropy of N d3 + .

Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, and density functional theory calculations.

Science.gov (United States)

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.

Structural and magnetic properties of Mn-implanted Si

International Nuclear Information System (INIS)

Zhou Shengqiang; Potzger, K.; Zhang Gufei; Muecklich, A.; Eichhorn, F.; Schell, N.; Groetzschel, R.; Schmidt, B.; Skorupa, W.; Helm, M.; Fassbender, J.; Geiger, D.

2007-01-01

Structural and magnetic properties in Mn-implanted, p-type Si were investigated. High resolution structural analysis techniques such as synchrotron x-ray diffraction revealed the formation of MnSi 1.7 nanoparticles already in the as-implanted samples. Depending on the Mn fluence, the size increases from 5 nm to 20 nm upon rapid thermal annealing. No significant evidence is found for Mn substituting Si sites either in the as-implanted or annealed samples. The observed ferromagnetism yields a saturation moment of 0.21μ B per implanted Mn at 10 K, which could be assigned to MnSi 1.7 nanoparticles as revealed by a temperature-dependent magnetization measurement

Schaum’s outline of fluid mechanics and hydraulics

CERN Document Server

Giles, Ranald V; Liu, Cheng

2014-01-01

Tough Test Questions? Missed Lectures? Not Enough Time? Fortunately, there's Schaum's. More than 40 million students have trusted Schaum's to help them succeed in the classroom and on exams. Schaum's is the key to faster learning and higher grades in every subject. Each Outline presents all the essential course information in an easy-to-follow, topic-by-topic format. You also get hundreds of examples, solved problems, and practice exercises to test your skills. This Schaum's Outline gives you: 622 fully solved problems; extra practice on topics such as buoyancy and flotation, complex pipeline systems, fluid machinery, flow in open channels, and more; and support for all the major textbooks for fluidmechanics and hydraulics courses. Fully compatible with your classroom text, Schaum's highlights all the important facts you need to know. Use Schaum's to shorten your study time - and get your best test scores! Schaum's Outlines - Problem Solved.

AUTOMATIC BUILDING OUTLINING FROM MULTI-VIEW OBLIQUE IMAGES

Directory of Open Access Journals (Sweden)

J. Xiao

2012-07-01

Full Text Available Automatic building detection plays an important role in many applications. Multiple overlapped airborne images as well as lidar point clouds are among the most popular data sources used for this purpose. Multi-view overlapped oblique images bear both height and colour information, and additionally we explicitly have access to the vertical extent of objects, therefore we explore the usability of this data source solely to detect and outline buildings in this paper. The outline can then be used for further 3D modelling. In the previous work, building hypotheses are generated using a box model based on detected façades from four directions. In each viewing direction, façade edges extracted from images and height information by stereo matching from an image pair is used for the façade detection. Given that many façades were missing due to occlusion or lack of texture whilst building roofs can be viewed in most images, this work mainly focuses on improve the building box outline by adding roof information. Stereo matched point cloud generated from oblique images are combined with the features from images. Initial roof patches are located in the point cloud. Then AdaBoost is used to integrate geometric and radiometric attributes extracted from oblique image on grid pixel level with the aim to refine the roof area. Generalized contours of the roof pixels are taken as building outlines. The preliminary test has been done by training with five buildings and testing around sixty building clusters. The proposed method performs well concerning covering the irregular roofs as well as improve the sides location of slope roof buildings. Outline result comparing with cadastral map shows almost all above 70% completeness and correctness in an area-based assessment, as well as 20% to 40% improvement in correctness with respect to our previous work.

Manganese-calcium intermixing facilitates heteroepitaxial growth at the mn>10mn><mn>1mn>¯>4mn> calcite-water interface

Energy Technology Data Exchange (ETDEWEB)

Xu, Man; Riechers, Shawn L.; Ilton, Eugene S.; Du, Yingge; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Qafoku, Odeta; Kerisit, Sebastien

2017-10-01

In situ atomic force microscopy (AFM) measurements were performed to probe surface precipitates that formed on the (10-14) surface of calcite (CaCO3) single crystals following reaction with Mn2+-bearing aqueous solutions with a range of initial concentrations. Three-dimensional epitaxial islands were observed to precipitate and grow on the surfaces and in situ time-sequenced measurements demonstrated that their growth rates were commensurate with those obtained for epitaxial islands formed on calcite crystals reacted with Cd2+-bearing aqueous solutions of the same range in supersaturation with respect to the pure metal carbonate phase. This finding was unexpected as rhodochrosite (MnCO3) and calcite display a 10% lattice mismatch, based on the area of their (10-14) surface unit cells, whereas the lattice mismatch is only 4% for otavite (CdCO3) and calcite. Coatings of varying thicknesses were therefore synthesized by reacting calcite single crystals with calcite-equilibrated aqueous solutions with concentrations of up to 250 µM MnCl2 and analyzed to determine the composition of the surface precipitates. Ex situ X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectivity (XRR), and AFM measurements of the reacted crystals demonstrated the formation of an epitaxial (Mn,Ca)CO3 solid solution with a spatially complex composition atop the calcite surface, whereby the first few nanometers were rich in Ca and the Mn content increased with distance from the original calcite surface, culminating in a topmost region of almost pure MnCO3 for the thickest coatings. These findings explain the measured growth rates (the effective lattice mismatch was much smaller than nominal mismatch) and highlight the strong influence played by the substrate on the composition of surface precipitates in aqueous conditions.

Analysing the integration of engineering in science lessons with the Engineering-Infused Lesson Rubric

Science.gov (United States)

Peterman, Karen; Daugherty, Jenny L.; Custer, Rodney L.; Ross, Julia M.

2017-09-01

Science teachers are being called on to incorporate engineering practices into their classrooms. This study explores whether the Engineering-Infused Lesson Rubric, a new rubric designed to target best practices in engineering education, could be used to evaluate the extent to which engineering is infused into online science lessons. Eighty lessons were selected at random from three online repositories, and coded with the rubric. Overall results documented the strengths of existing lessons, as well as many components that teachers might strengthen. In addition, a subset of characteristics was found to distinguish lessons with the highest level of engineering infusion. Findings are discussed in relation to the potential of the rubric to help teachers use research evidence-informed practice generally, and in relation to the new content demands of the U.S. Next Generation Science Standards, in particular.

Coupling between magnetic, dielectric properties and crystal structure in MnT2O4 (T = V, Cr, Mn)

International Nuclear Information System (INIS)

Suzuki, T; Adachi, K; Katsufuji, T

2006-01-01

We measured the temperature dependence of dielectric constant and striction for spinel MnT 2 O 4 (T = V, Cr, Mn) under magnetic field. We found critical changes of the dielectric constant and striction with ferrimagnetic ordering as well as applied magnetic field in MnV 2 O 4 and Mn 3 O 4 , which have orbital degree of freedom in the T 3+ ion. This result indicates the importance of the orbital degree of freedom for the coupling between dielectric, magnetic properties and crystal structure in these spinel compounds

With Interest It Comes To...Unconscionable Clauses in Sales Contracts. A Student's Lesson Plan [and] A Teacher's Lesson Plan [and] A Lawyer's Lesson Plan.

Science.gov (United States)

Howard, Estelle; And Others

One of a series of secondary level teaching units presenting case studies with pro and con analysis of particular legal problems, the document presents a student's lesson plan, a teacher's lesson plan, and a lawyer's lesson plan on unconscionable clauses in sales contracts. The unit acquaints students with the operation of sales contracts and…

Structural, magnetic and transport properties of Mn3.1Sn0.9 and Mn3.1Sn0.9N compounds

International Nuclear Information System (INIS)

Feng, W.J.; Li, D.; Ren, W.J.; Li, Y.B.; Li, W.F.; Li, J.; Zhang, Y.Q.; Zhang, Z.D.

2007-01-01

The cubic anti-perovskite Mn 3.1 Sn 0.9 N compound is prepared via nitrogenation of the hexagonal Mn 3.1 Sn 0.9 compound. A magnetic phase diagram of Mn 3.1 Sn 0.9 compound is constructed by analysis of data of its magnetic properties. For Mn 3.1 Sn 0.9 N compound, parasitic ferromagnetism exists in the temperature range of 5-370 K, besides a spin-reorientation at about 280 K. Mn 3.1 Sn 0.9 compound exhibits a metallic conducting behavior, while Mn 3.1 Sn 0.9 N displays a metal-nonmetal transition due to the electron localization caused by the static disorder. The differences of the physical properties between the both compounds, are discussed, in terms of the correlation of the hexagonal DO 19 and the cubic anti-perovskite structures, the reduction of the distances between Mn atoms, and the spin-pairing or charge transfer effect due to the electron donation by N 2p to Mn 3d states after introduction of N atoms into the interstitial sites of Mn 3.1 Sn 0.9 compound

Li(Zn,Co,MnAs: A bulk form diluted magnetic semiconductor with Co and Mn co-doping at Zn sites

Directory of Open Access Journals (Sweden)

Bijuan Chen

2016-11-01

Full Text Available We report the synthesis and characterization of a series of bulk forms of diluted magnetic semiconductors Li(Zn1-x-yCoxMnyAs with a crystal structure close to that of III-V diluted magnetic semiconductor (Ga,MnAs. No ferromagnetic order occurs with single (Zn,Co or (Zn, Mn substitution in the parent compound LiZnAs. Only with co-doped Co and Mn ferromagnetic ordering can occur at the Curie temperature ∼40 K. The maximum saturation moment of the this system reached to 2.17μB/Mn, which is comparable to that of Li (Zn,MnAs. It is the first time that a diluted magnetic semiconductor with co-doping Co and Mn into Zn sites is achieved in “111” LiZnAs system, which could be utilized to investigate the basic science of ferromagnetism in diluted magnetic semiconductors. In addition, ferromagnetic Li(Zn,Co,MnAs, antiferromagnetic LiMnAs, and superconducting LiFeAs share square lattice at As layers, which may enable the development of novel heterojunction devices in the future.

Synthesis of highly efficient Mn{sub 2}O{sub 3} catalysts for CO oxidation derived from Mn-MIL-100

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiaodong, E-mail: fatzhxd@126.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Li, Hongxin; Hou, Fulin; Yang, Yang; Dong, Han; Liu, Ning [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Wang, Yuxin [Institute of Applied Biotechnology, Taizhou Vocation & Technical College, Taizhou, Zhejiang 318000 (China); Cui, Lifeng, E-mail: lifeng.cui@gmail.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China)

2017-07-31

Highlights: • The morphology of porous Mn{sub 2}O{sub 3} cubes was inherited from Mn-MIL-100 template. • Mn{sub 2}O{sub 3} obtained at calcined temperature of 700 °C displayed high activity. • Enhanced activity is attributed to surface active oxygen, and reduction behavior. - Abstract: In this work, metal-organic frameworks (MOFs) Mn-MIL-100 were first prepared, which were next used as templates to obtain the irregular porous Mn{sub 2}O{sub 3} cubes through calcination with air at different temperature. The catalysts were characterized by N{sub 2} adsorption-desorption, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), H{sub 2}-temperature program reduction (H{sub 2}-TPR) and X-ray photoelectron spectroscopic (XPS). The catalytic activity for CO oxidation over Mn{sub 2}O{sub 3} catalysts was investigated. It was found that calcination temperature had a strong effect on the structure and catalytic activity of Mn{sub 2}O{sub 3} catalyst. Mn{sub 2}O{sub 3} catalyst obtained by calcined at 700 °C (Mn{sub 2}O{sub 3}-700) showed a smaller specific surface area, but displayed a high catalytic activity and excellent stability with a complete CO conversion temperature (T{sub 98}) of 240 °C, which was attributed to the unique structure, a high quantity of surface active oxygen species, smaller particle size, oxygen vacancies and good low temperature reduction behavior. The effect of water vapor on catalytic activity was also examined. The introduction of water vapor to the feedstock induced a positive effect on CO oxidation over Mn{sub 2}O{sub 3}-700 catalyst. Furthermore, no obvious drop is observed in activity over catalysts even in the presence of water vapor during 48 h.

Lessons learned related to packaging and transportation

International Nuclear Information System (INIS)

Wallen, C.

1995-01-01

The use of lessons learned as a tool for learning from past experiences is well established, especially by many organizations within the nuclear industry. Every person has, at some time, used the principles of lessons learned to adopt good work practices based on their own experiences or the experiences of others. Lessons learned can also help to avoid the recurrence of adverse practices, which is often an area that most lessons-learned programs tend to focus on. This paper will discuss how lessons learned relate to packaging and transportation issues and events experienced at Department of Energy (DOE) facilities. It will also discuss the role performed by the Office of Nuclear and Facility Safety's Office of Operating Experience Analysis and Feedback in disseminating lessons learned and operating experience feedback to the DOE complex. The central concept of lessons learned is that any organization should be able to learn from its own experiences and events. In addition, organizations should implement methodologies to scan external environments for lessons learned, to analyze and determine the relevance of lessons learned, and to bring about the necessary changes learned from these experiences. With increased concerns toward facility safety, the importance of utilizing the lessons-learned principles and the establishment of lessons-learned programs can not be overstated

Self-assembled decanuclear Na(I)2Mn(II)4Mn(III)4 complexes: from discrete clusters to 1-D and 2-D structures, with the Mn(II)4Mn(III)4 unit displaying a large spin ground state and probable SMM behaviour.

Science.gov (United States)

Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

2011-12-07

The synthesis, magnetic characterization and X-ray crystal structures are reported for five new manganese compounds, [Mn(III)(teaH(2))(sal)]·(1/2)H(2)O (1), [Na(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(MeOH)(4)]·6MeOH (2), [Na(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(MeOH)(2)](n)·7MeOH (3), [Na(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(MeOH)(2)](n)·2MeOH·Et(2)O (4) and [K(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(H(2)O)(2)](n)·5MeOH (5). Complex 1 is a mononuclear compound, formed via the reaction of Mn(NO(3))(2)·4H(2)O, triethanolamine (teaH(3)) and salicylic acid (salH(2)) in a basic methanolic solution. Compound 2 is a mixed-valent hetero-metallic cluster made up of a Mn(8)Na(2) decanuclear core and is formed via the reaction of sodium azide (NaN(3)) with 1. Compounds 3-5 are isolated as 1- or 2-D coordination polymers, each containing the decanuclear Mn(8)M(2) (M = Na(+) or K(+)) core building block as the repeating unit. Compound 3 is isolated when 1 is reacted with NaN(3) over a very short reaction time and forms a 1-D coordination polymer. Each unit displays inter-cluster bridges via the O-atoms of teaH(2-) ligands bonding to the sodium ions of an adjacent cluster. Increasing the reaction time appears to drive the formation of 4 which forms 2-D polymeric sheets and is a packing polymorph of 3. The addition of KMnO(4) and NaN(3) to 1 resulted in compound 5, which also forms a 1-D coordination polymer of the decanuclear core unit. The 1-D chains are now linked via inter-cluster potassium and salicylate bridges. Solid state DC susceptibility measurements were performed on compounds 1-5. The data for 1 are as expected for an S = 2 Mn(III) ion, with the isothermal M vs. H data being fitted by matrix diagonalization methods to give values of g and the axial (D) and rhombic (E) zero field splitting parameters of 2.02, -2.70 cm(-1) and 0.36 cm(-1) respectively. The data for 2-5, each with an identical Mn(II)(4)Mn(III)(4

Cardiovascular effects of MnDPDP and MnCl2 in dogs with acute ischaemic heart failure

International Nuclear Information System (INIS)

Karlsson, J.O.G.; Pedersen, H.K.; Sager, G.; Refsum, H.; Nycomed Imaging AS, Oslo

1997-01-01

Purpose: To examine the cardiovascular effects of MnDPDP in a model of acute heart failure in the dog, and to compare these effects with those of MnCl 2 . Material and Methods: The study involved slow i.v. infusion of either 10, 60 and 300 μmol/kg of MnDPDP, or 1, 6 and 30 μmol/kg MnCl 2 , in increasing doses to groups of 5 dogs. Acute ischaemic heart failure was first induced by injection of polystyrene microspheres (50±10 μm) into the left coronary artery until a stable left ventricular end-diastolic pressure of approximately 20 mm Hg was achieved. The following test parameters were measured: Left ventricular end-diastolic pressure; the first derivatives of maximum rate of left ventricular contraction and relaxation; mean aortic pressure; pulmonary artery pressure; right atrial pressure; cardiac ouput; heart rate; QT-time; PQ-time; QRS-width; and plasma catecholamines. Results: Slow infusion of MnDPDP at doses up to and including 12 times the clinical dose was well tolerated in dogs without further depression of cardiovascular function during acute ischaemic heart failure. At 300 μmol/kg, i.e. 60 times the human dose, only minor haemodynamic and electrophysiological effects were seen, and these were similar to those seen after administration of 30 μmol/kg MnCl 2 . (orig./AJ)

NMRON on a mixed halide antiferromagnet, (54Mn)Mn(Cl0.6Br0.4)2.4H2O

International Nuclear Information System (INIS)

Chaplin, D.H.; Harker, S.J.; Hutchison, W.D.; Bowden, G.J.

2000-01-01

Full text: Recently we reported on the significant gains that can be made in Low Temperature Nuclear Orientation (LTNO) of the magnetically dominant species in an antiferromagnetic single crystal by heterogeneous mixing of the halide ligands. This new approach relies on enhanced nuclear spin lattice relaxation (NSLR) at the magnetic ion, in this case Mn, through broadbanded electronic magnons, in the cooled, single crystal host. Whereas the isomorphous terminal compounds ( 54 Mn)MnCI 2 .4H 2 O and ( 54 Mn)MnBr 2 .4H 2 O, have yielded zero field directional anisotropies of only 5% and 14%, respectively, from the daughter gamma from the long-lived parent 54 Mn, the mixed halides have yielded up to 40% zero field gamma anisotropy at the same base temperature of about 7-8 millikelvin. This improved zero field LTNO provides sufficient sensitivity to enable meaningful NMRON studies of the details of the hyperfine parameters at the Mn site in these mixed halide systems. In this paper we provide the NMRON results for single crystal ( 54 Mn)Mn(CI 0.6 Br 0.4 ) 2 .4H 2 O and compare them with the two terminal compounds which possess surprisingly different NMR responses due to different ratios of magnetic exchange to magnetic anisotropy fields. It is shown that whereas the static magnetic hyperfine field at the Mn nucleus is largely unchanged, and the spin flop field nicely interpolates when compared with the terminal compounds, there are significant differences in the pseudoquadrupolar splittings and sub-resonance linewidths

Luminescence of nanocrystalline ZnSe:Mn2+

NARCIS (Netherlands)

Suyver, J.F.; Wuister, S.F.; Kelly, J.J.; Meijerink, A.

2000-01-01

The luminescence properties of nanocrystalline ZnSe:Mn^(2+) prepared via an inorganic chemical synthesis are described. Photoluminescence spectra show distinct ZnSe and Mn^(2+) related emissions, both of which are excited via the ZnSe host lattice. The Mn^(2+) emission wavelength and the

Kineococcus radiotolerans Dps forms a heteronuclear Mn-Fe ferroxidase center that may explain the Mn-dependent protection against oxidative stress.

Science.gov (United States)

Ardini, Matteo; Fiorillo, Annarita; Fittipaldi, Maria; Stefanini, Simonetta; Gatteschi, Dante; Ilari, Andrea; Chiancone, Emilia

2013-06-01

The ferroxidase center of DNA-binding protein from starved cells (Dps) is a major player in the iron oxidation/detoxification process that leads to a decreased reactive oxygen species production. The possible Mn(II) participation in this process has been studied in Dps from Kineococcus radiotolerans, a radiation-resistant bacterium with a high cytosolic Mn/Fe ratio and a high capacity to survive ionizing and stress conditions. The X-ray structure of recombinant K. radiotolerans Dps loaded with Mn(II) has been solved at 2.0Å resolution. Mn(II) binding to K. radiotolerans Dps and its effect on Fe(II) oxidation have been characterized in spectroscopic measurements. In K. radiotolerans Dps, the Fe-Fe ferroxidase center can have a Mn-Fe composition. Mn(II) binds only at the high affinity, so-called A site, whereas Fe(II) binds also at the low affinity, so-called B site. The Mn-Fe and Fe-Fe centers behave distinctly upon iron oxidation by O2. A site-bound Mn(II) or Fe(II) plays a catalytic role, while B site-bound Fe(II) behaves like a substrate and can be replaced by another Fe(II) after oxidation. When H2O2 is the Fe(II) oxidant, single electrons are transferred to aromatic residues near the ferroxidase center and give rise to intra-protein radicals thereby limiting OH release in solution. The presence of the Mn-Fe center results in significant differences in the development of such intra-protein radicals. Mn(II) bound at the Dps ferroxidase center A site undergoes redox cycling provided the B site contains Fe. The results provide a likely molecular mechanism for the protective role of Mn(II) under oxidative stress conditions as it participates in redox cycling in the hetero-binuclear ferroxidase center. Copyright © 2013 Elsevier B.V. All rights reserved.

τ-MnAl with high coercivity and saturation magnetization

Directory of Open Access Journals (Sweden)

J. Z. Wei

2014-12-01

Full Text Available In this paper, high purity τ-Mn54Al46 and Mn54−xAl46Cxalloys were successfully prepared using conventional arc-melting, melt-spinning, and heat treatment process. The magnetic and the structural properties were examined using x-ray diffraction (XRD, powder neutron diffraction and magnetic measurements. A room temperature saturation magnetization of 650.5 kAm-1, coercivity of 0.5 T, and a maximum energy product of (BHmax = 24.7 kJm-3 were achieved for the pure Mn54Al46 powders without carbon doping. The carbon substituted Mn54−xAl46Cx, however, reveals a lower Curie temperature but similar saturation magnetization as compared to the carbon-free sample. The electronic structure of MnAl shows that the Mn atom possesses a magnetic moment of 2.454 μB which results from strong hybridization between Mn-Al and Mn-Mn. We also investigated the volume and c/a ratio dependence of the magnetic moments of Mn and Al. The results indicate that an increase in the intra-atomic exchange splitting due to the cell volume expansion, leads to a large magnetic moment for the Mn atom. The Mn magnetic moment can reach a value of 2.9 μB at a volume expansion rate of ΔV/V ≈ 20%.

Fe-Mn-Si based shape memory alloys

International Nuclear Information System (INIS)

Hsu, T.Y.

2000-01-01

Characteristics of martensitic transformation fcc(γ)→hcp(ε) in Fe-Mn-Si based alloys are briefly reviewed. By analyzing the influences of constituents and treatments on shape memory effect (SME) in Fe-Mn-Si, the main factors controlling SME are summarized as austenite strengthening, stacking fault energy (probability) and antiferromagnetic temperature. Contribution of thermomechanical training to SME is introduced. The Fe-Mn-Si-RE (rare earth elements) and Fe-Mn-Si-Cr-N alloys are recommended as two novel shape memory alloys with superior SME. (orig.)

Preparation and characterization of the non-stoichiometric La–Mn perovskites

International Nuclear Information System (INIS)

Gao, Zhiming; Wang, Huishu; Ma, Hongwei; Li, Zhanping

2015-01-01

Six La–Mn oxide samples with La/Mn atomic ratio x = 1.03–0.56 (denoted as sample LaxMn) were prepared by the citrate method with calcination at 700 °C for 5 h, and characterized by X-ray diffraction (XRD), N 2 adsorption–desorption, temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). It is confirmed that the four samples with La/Mn atomic ratio at 1.03–0.72 are all single phase perovskites by XRD patterns. Lattice parameters of the perovskites are varying with the La/Mn atomic ratio. As the La/Mn atomic ratio further lowers to 0.63 and 0.56, Mn 3 O 4 phase is formed besides the main phase of perovskite. Lattice vacancy at the A-sites of the perovskites is present for all the six samples, and there are an appreciable number of Mn 4+ ions in the perovskite crystal according to the refinement results of the Rietveld method. XPS analyses indicate that Mn ions are enriched on the surfaces of all the samples. In addition, catalytic activity for methane oxidation is in an order of sample La 0.89 Mn > La 1.03 Mn > La 0.81 Mn > La 0.72 Mn > La 0.63 Mn > La 0.56 Mn. - Highlights: • The samples with La/Mn atomic ratio at 1.03–0.72 are single phase perovskites. • Cationic lattice vacancies are present in the perovskite crystal of the samples. • Surface of the samples is enriched by Mn ions. • The sample La 0.89 Mn is most catalytically active for methane oxidation

Impact of environmental chemistry on mycogenic Mn oxide minerals

Science.gov (United States)

Santelli, C. M.; Farfan, G. A.; Post, A.; Post, J. E.

2012-12-01

Manganese (Mn) oxide minerals are ubiquitous in aquatic and terrestrial environments and their presence can have broad environmental consequences. In particular, Mn oxides scavenge nutrients and metals, degrade complex organics, and oxidize a variety of inorganic contaminants. The "reactivity" of Mn oxides, however, is highly dependent upon crystallite size, composition, and structure, which are largely determined by environmental factors such as solution chemistry. It is has been suggested that most Mn oxides in terrestrial and aquatic environments are formed by microbial activity; indeed, a diversity of Mn(II)-oxidizing bacteria and fungi have been isolated and their mineral byproducts are consistent with those observed in natural systems. Previous studies showed that Mn(II)-oxidizing Ascomycete fungi produce highly-disordered, nanocrystalline Mn oxides that are structurally similar to synthetic δ-MnO2 or natural vernadite. Unlike related studies with Mn-oxidizing bacteria, Mn oxides produced by these fungi did not "age" or transform to more crystalline mineral phases with time. We hypothesize that fungal growth conditions, in particular the low concentration of cations, are inhibiting secondary mineral formation. The overall goal of this research is to examine the structure and speciation of fungally-precipitated Mn oxides with respect to fungal species, time, and concentration of soluble Mn(II), Na, and Ca - three environmentally relevant cations that promote the transformation of δ-MnO2 to more crystalline mineral phases such as feitknechtite, birnessite, or ranciéite. For this study, we examined the Mn oxides formed by different species of Mn(II)-oxidizing fungi (Pyrenochaeta sp., Stagonospora sp., Plectosphaerella cucumerina., and Acremonium strictum). Isolates were grown for 8 or 16 days in a nutrient lean media consisting of yeast extract, trace elements and 0.2 mM MnCl2 supplemented with varying concentrations of Na, Ca, or Mn(II) compounds. The

Lessons for Teaching Art Criticism.

Science.gov (United States)

Barrett, Terry, Ed.; Clark, Gilbert, Ed.

This collection of lessons is meant to be a practical guide to help teachers engage children in art criticism. The lessons generally follow a similar format. Most suggest an age group but may be modified for use with younger or older students. Several authors suggest variations and extensions for lessons that include studio activities. A broad…

"Frankenstein." [Lesson Plan].

Science.gov (United States)

Simon, Melanie

Based on Mary Shelley's novel "Frankenstein," this lesson plan presents activities designed to help students understand that active readers interpret a novel (its characters, plot, setting, and theme) in different ways; and the great literature can be and has been adapted in many ways over time. The main activity of the lesson involves students…

Phagocytosis: history's lessons.

Science.gov (United States)

Garg, Manish; Chandawarkar, Rajiv Y

2013-01-01

The assimilation of lessons from the past is an essential component of education for scientists of tomorrow. These lessons are not easy to find. History books on science are few and usually highly dramatized and biographies of scientists tend to exaggerate the pomp of scientific discovery. Both underplay the hard and laborious work that is integral to any scientific pursuit. Here we illustrate one such example. A century ago, the Nobel Prize in Medicine was awarded to two scientists: Ilya Metchnikoff, a Russian zoologist, for the discovery ofphagocytosis-a cell-mediated ingestion ofmicrobes; and Paul Ehrlich, a distinguished physician-scientist, for discovering a highly antigen-specific serum-derived antibody-based immune defense. These two diametrically opposing views of the host-pathogen interaction set the stage for a strife that led to seminal advancements in immunology. Mirrored in this journey are important lessons for scientists today--ubiquitously as applicable to modern scientific life as they were a century ago. This commentaryhighlights these lessons--a fitting centenary to a well-deserved recognition.

Curriculum Outline for Tennessee Transition Model.

Science.gov (United States)

Esch, B. J.

This curriculum outline for the Sevier County, Tennessee, transition program for special needs students provides goals and objectives for the following domains: domestic, vocational, community functioning, and recreation/leisure. The domestic domain covers personal hygiene/grooming, first aid, home nursing, birth control/pregnancy, parenting, drug…

Electronic Topological Transitions in CuNiMnAl and CuNiMnSn under pressure from first principles study

Science.gov (United States)

Rambabu, P.; Kanchana, V.

2018-06-01

A detailed study on quaternary ordered full Heusler alloys CuNiMnAl and CuNiMnSn at ambient and under different compressions is presented using first principles electronic structure calculations. Both the compounds are found to possess ferromagnetic nature at ambient with magnetic moment of Mn being 3.14 μB and 3.35 μB respectively in CuNiMnAl and CuNiMnSn. The total magnetic moment for both the compounds is found to decrease under compression. Fermi surface (FS) topology change is observed in both compounds under pressure at V/V0 = 0.90, further leading to Electronic Topological Transitions (ETTs) and is evidenced by the anomalies visualized in density of states and elastic constants under compression.

Ferromagnetic properties of Mn-doped AlN

International Nuclear Information System (INIS)

Li, H.; Bao, H.Q.; Song, B.; Wang, W.J.; Chen, X.L.; He, L.J.; Yuan, W.X.

2008-01-01

Mn-doped AlN polycrystalline powders with a wurtzite structure were synthesized by solid-state reactions. A red-orange band at 600 nm, due to Mn 3+ incorporated into the AlN lattice, is observed in the photoluminescence (PL) spectrum at room temperature (RT). Magnetic measurements show the samples possess hysteresis loops up to 300 K, indicating that the obtained powders are ferromagnetic at around RT. The Mn concentration-induced RT ferromagnetism is less than 1 at%. Our results confirm that the RT ferromagnetism can be realized in Mn-doped AlN

An annotated outline for a traffic management center operations manual

Science.gov (United States)

2000-10-01

This draft Traffic Management Center (TMC) and Operations manual outline is meant to serve as a model "checklist" for the development of similar manuals used in deployed environments. The purpose of this outline is to provide a reference for agencies...

Preparation, characteristics and electrochemical properties of surface-modified LiMn2O4 by doped LiNi0.05Mn1.95O4

International Nuclear Information System (INIS)

Yuan, Y.F.; Wu, H.M.; Guo, S.Y.; Wu, J.B.; Yang, J.L.; Wang, X.L.; Tu, J.P.

2008-01-01

The surface-modified spinel LiMn 2 O 4 by doped LiNi 0.05 Mn 1.95 O 4 was prepared by a tartaric acid gel method. Transmission electron microscope (TEM) images indicated that some small particles with 100-200 nm in diameter modified the surface of large particle LiMn 2 O 4 . Energy dispersive spectrometry (EDS) showed that the particles were LiNi 0.05 Mn 1.95 O 4 . Electrochemical properties of LiNi 0.05 Mn 1.95 O 4 -modified spinel LiMn 2 O 4 were intensively investigated by the galvanostatic charge-discharge tests, cyclic voltammetry (CV) and AC impedance measurements. The doped LiNi 0.05 Mn 1.95 O 4 -modified LiMn 2 O 4 cathode delivered the same initial discharge capacity as the unmodified LiMn 2 O 4 , but its cyclic stability was evidently improved, the capacity retention ratio reached 96% after 20 cycles, being higher than 89% of the unmodified LiMn 2 O 4 . Cyclic voltammograms of the LiNi 0.05 Mn 1.95 O 4 -modified LiMn 2 O 4 did not markedly change while the semicircle diameter of AC impedance spectra evidently decreased after 20 cycles, which showed that the surface modification with LiNi 0.05 Mn 1.95 O 4 improved the electrochemical activity and cycling stability of LiMn 2 O 4 .

Noncollinear antiferromagnetic Mn3Sn films

Science.gov (United States)

Markou, A.; Taylor, J. M.; Kalache, A.; Werner, P.; Parkin, S. S. P.; Felser, C.

2018-05-01

Noncollinear hexagonal antiferromagnets with almost zero net magnetization were recently shown to demonstrate giant anomalous Hall effect. Here, we present the structural and magnetic properties of noncollinear antiferromagnetic Mn3Sn thin films heteroepitaxially grown on Y:ZrO2 (111) substrates with a Ru underlayer. The Mn3Sn films were crystallized in the hexagonal D 019 structure with c -axis preferred (0001) crystal orientation. The Mn3Sn films are discontinuous, forming large islands of approximately 400 nm in width, but are chemical homogeneous and characterized by near perfect heteroepitaxy. Furthermore, the thin films show weak ferromagnetism with an in-plane uncompensated magnetization of M =34 kA/m and coercivity of μ0Hc=4.0 mT at room temperature. Additionally, the exchange bias effect was studied in Mn3Sn /Py bilayers. Exchange bias fields up to μ0HEB=12.6 mT can be achieved at 5 K. These results show Mn3Sn films to be an attractive material for applications in antiferromagnetic spintronics.

Molecular orbital (SCF-X-α-SW) theory of Fe2+-Mn3+, Fe3+-Mn2+, and Fe3+-Mn3+ charge transfer and magnetic exchange in oxides and silicates

Science.gov (United States)

Sherman, David M.

1990-01-01

Metal-metal charge-transfer and magnetic exchange interactions have important effects on the optical spectra, crystal chemistry, and physics of minerals. Previous molecular orbital calculations have provided insight on the nature of Fe2+-Fe3+ and Fe2+-Ti4+ charge-transfer transitions in oxides and silicates. In this work, spin-unrestricted molecular orbital calculations on (FeMnO10) clusters are used to study the nature of magnetic exchange and electron delocalization (charge transfer) associated with Fe3+-Mn2+, Fe3+-Mn3+, and Fe2+-Mn3+ interactions in oxides and silicates. 

Dissimilatory Fe(III) and Mn(IV) reduction.

Science.gov (United States)

Lovley, D R

1991-06-01

The oxidation of organic matter coupled to the reduction of Fe(III) or Mn(IV) is one of the most important biogeochemical reactions in aquatic sediments, soils, and groundwater. This process, which may have been the first globally significant mechanism for the oxidation of organic matter to carbon dioxide, plays an important role in the oxidation of natural and contaminant organic compounds in a variety of environments and contributes to other phenomena of widespread significance such as the release of metals and nutrients into water supplies, the magnetization of sediments, and the corrosion of metal. Until recently, much of the Fe(III) and Mn(IV) reduction in sedimentary environments was considered to be the result of nonenzymatic processes. However, microorganisms which can effectively couple the oxidation of organic compounds to the reduction of Fe(III) or Mn(IV) have recently been discovered. With Fe(III) or Mn(IV) as the sole electron acceptor, these organisms can completely oxidize fatty acids, hydrogen, or a variety of monoaromatic compounds. This metabolism provides energy to support growth. Sugars and amino acids can be completely oxidized by the cooperative activity of fermentative microorganisms and hydrogen- and fatty-acid-oxidizing Fe(III) and Mn(IV) reducers. This provides a microbial mechanism for the oxidation of the complex assemblage of sedimentary organic matter in Fe(III)- or Mn(IV)-reducing environments. The available evidence indicates that this enzymatic reduction of Fe(III) or Mn(IV) accounts for most of the oxidation of organic matter coupled to reduction of Fe(III) and Mn(IV) in sedimentary environments. Little is known about the diversity and ecology of the microorganisms responsible for Fe(III) and Mn(IV) reduction, and only preliminary studies have been conducted on the physiology and biochemistry of this process.

Polycrystalline Mn-alloyed indium tin oxide films

International Nuclear Information System (INIS)

Scarlat, Camelia; Schmidt, Heidemarie; Xu, Qingyu; Vinnichenko, Mykola; Kolitsch, Andreas; Helm, Manfred; Iacomi, Felicia

2008-01-01

Magnetic ITO films are interesting for integrating ITO into magneto-optoelectronic devices. We investigated n-conducting indium tin oxide (ITO) films with different Mn doping concentration which have been grown by chemical vapour deposition using targets with the atomic ratio In:Sn:Mn=122:12:0,114:12:7, and 109:12:13. The average film roughness ranges between 30 and 50 nm and XRD patterns revealed a polycrystalline structure. Magnetotransport measurements revealed negative magnetoresistance for all the samples, but high field positive MR can be clearly observed at 5 K with increasing Mn doping concentration. Spectroscopic ellipsometry (SE) has been used to prove the existence of midgap states in the Mn-alloyed ITO films revealing a transmittance less than 80%. A reasonable model for the ca. 250 nm thick Mn-alloyed ITO films has been developed to extract optical constants from SE data below 3 eV. Depending on the Mn content, a Lorentz oscillator placed between 1 and 2 eV was used to model optical absorption below the band gap

Effect of Fe substitution at the Ni and Mn sites on the magnetic properties of Ni50Mn35In15 Heusler alloys

International Nuclear Information System (INIS)

Halder, Madhumita; Suresh, K.G.

2015-01-01

The structural and magnetic properties of Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 Heusler alloys have been investigated. At room temperature, Ni 48 Fe 2 Mn 35 In 15 has L2 1 cubic structure, whereas Ni 50 Mn 34 FeIn 15 shows a two-phase structure due to the martensitic transition. In the case of Ni 48 Fe 2 Mn 35 In 15 , there is only one magnetic transition at 316 K with no martensitic transition. However, in Ni 50 Mn 34 FeIn 15 , we observe the martensitic transition at about 280 K. The Curie temperatures for austenite and martensite phases are 314 and 200 K, respectively. The maximum magnetic entropy changes are found to be 5.5 and 4.5 J kg −1 K −1 for Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 , respectively, for 50 kOe. Ni 50 Mn 34 FeIn 15 exhibits exchange bias behavior, with a bias field of 130 Oe at 5 K. Both the alloys satisfy the empirical relation between the martensitic transition and the valence electron concentration (e/a) ratio. - Highlights: • Structural and magnetic properties of Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 Heusler alloys have been investigated. • Ni 48 Fe 2 Mn 35 In 15 does not undergo a martensitic transition, whereas Ni 50 Mn 34 FeIn 15 shows martensitic transition. • Ni 50 Mn 34 FeIn 15 alloy exhibits exchange bias behavior. • Both alloys satisfy the empirical relation between martensitic transition and valence electron concentration (e/a)

Atomic and magnetic structure of MnF3

International Nuclear Information System (INIS)

Hunter, B.A.; Kennedy, B.J.; Vogt, T.

2003-01-01

Full text: The magnetic and atomic structure of MnF 3 has been determined from 4K to 300K using neutron powder diffraction. The MnF 3 compound is the archetypical Mn-based colossal magnetoresistive compound. A Neel temperature of approximately 40K was observed from the temperature variation of the magnetic moment. Below the Neel temperature a large negative thermal expansion was observed, in striking similarity to other Mn-based colossal magnetoresistive compounds. The variation in structure is discussed in relation to other Mn-based compounds, particularly as this compound cannot support charge ordering

Mn L{sub 2,3}-edge X-ray absorption spectroscopic studies on charge-discharge mechanism of Li{sub 2}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Kubobuchi, Kei, E-mail: kubobuchi@nissan-arc.co.jp [NISSAN ARC Ltd., 1 Natsushima, Yokosuka 237-0061 (Japan); Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan. (Japan); Mogi, Masato; Imai, Hideto [NISSAN ARC Ltd., 1 Natsushima, Yokosuka 237-0061 (Japan); Ikeno, Hidekazu [Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Tanaka, Isao [Department of Materials Science and Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan. (Japan)

2014-02-03

The redox reaction of Mn in Li{sub 2}MnO{sub 3} was studied by X-ray absorption spectroscopy and ab initio multiplet calculation. Associated with the de-intercalation of Li-ion, small but clear spectral changes were observed in Mn-L{sub 2,3} X-ray absorption near edge structure (XANES). The systematic ab initio multiplet calculations of Mn-L{sub 2,3} XANES revealed that the spectral changes in the experiment could not simply be ascribed to the change of the valency from Mn{sup 4+} to Mn{sup 5+} but can be explained well by the changes of local atomic structures around Mn{sup 4+} due to the Li de-intercalation. Our results suggest that the electronic state of oxygen should change during charging in Li{sub 2}MnO{sub 3}.

The German energy transition. Design, implementeation, cost and lessons

Energy Technology Data Exchange (ETDEWEB)

Unnerstall, Thomas

2017-07-01

The book presents a comprehensive and systematic account of the concept, the current status and the costs of the German energy transition: the Energiewende. Written by an insider who has been working in the German energy industry for over 20 years, it follows a strictly non-political, neutral approach and clearly outlines the most relevant facts and figures. In particular, it describes the main impacts of the Energiewende on the German power system and Germany's national economy. Furthermore, it addresses questions that are of global interest with respect to energy transitions, such as the cost to the national economy, the financial burden on private households and companies and the actual effects on CO{sub 2} emissions. The book also discusses what could have been done better in terms of planning and implementing the Energiewende, and identifies important lessons for other countries that are considering a similar energy transition.

The German energy transition. Design, implementeation, cost and lessons

International Nuclear Information System (INIS)

Unnerstall, Thomas

2017-01-01

The book presents a comprehensive and systematic account of the concept, the current status and the costs of the German energy transition: the Energiewende. Written by an insider who has been working in the German energy industry for over 20 years, it follows a strictly non-political, neutral approach and clearly outlines the most relevant facts and figures. In particular, it describes the main impacts of the Energiewende on the German power system and Germany's national economy. Furthermore, it addresses questions that are of global interest with respect to energy transitions, such as the cost to the national economy, the financial burden on private households and companies and the actual effects on CO 2 emissions. The book also discusses what could have been done better in terms of planning and implementing the Energiewende, and identifies important lessons for other countries that are considering a similar energy transition.

Making Progress in Content and Language Integrated Learning (CLIL Lessons: An Indonesian Tertiary Context

Directory of Open Access Journals (Sweden)

Manafe Novriani Rabeka

2018-01-01

Full Text Available This paper outlines an attempt to discover students’ progress in both content and language skill in a content and language integrated learning (CLIL lessons at an Indonesia’s higher education context. This is a part of a research conducted at Faculty of Science and Technology of Nusa Cendana University in Kupang, East Nusa Tenggara Province. This study employs mixed method approach with 20 participants attending by taking pre-test and post-test as well as joining a focus group interview particularly for 6 students. The tests were aimed at measuring the participants’ comprehension of English as the language of CLIL lesson. They were also used as the tool to evaluate students’ mastery of Mathematics as the content subject. Based on the post-test results, the findings showed that more students made significant progress in content subject in comparison to their achievement in language proficiency. Regarding the interview, the students admitted that their failure to made progress in both subjects were mainly caused by their inadequate level of English. This, therefore, led to rising anxiety among the students to complete the tests.

CNS bioavailability and radiation protection of normal hippocampal neurogenesis by a lipophilic Mn porphyrin-based superoxide dismutase mimic, MnTnBuOE-2-PyP5+

Directory of Open Access Journals (Sweden)

David Leu

2017-08-01

Full Text Available Although radiation therapy can be effective against cancer, potential damage to normal tissues limits the amount that can be safely administered. In central nervous system (CNS, radiation damage to normal tissues is presented, in part, as suppressed hippocampal neurogenesis and impaired cognitive functions. Mn porphyrin (MnP-based redox active drugs have demonstrated differential effects on cancer and normal tissues in experimental animals that lead to protection of normal tissues and radio- and chemo-sensitization of cancers. To test the efficacy of MnPs in CNS radioprotection, we first examined the tissue levels of three different MnPs – MnTE-2-PyP5+(MnE, MnTnHex-2-PyP5+(MnHex, and MnTnBuOE-2-PyP5+(MnBuOE. Nanomolar concentrations of MnHex and MnBuOE were detected in various brain regions after daily subcutaneous administration, and MnBuOE was well tolerated at a daily dose of 3 mg/kg. Administration of MnBuOE for one week before cranial irradiation and continued for one week afterwards supported production and long-term survival of newborn neurons in the hippocampal dentate gyrus. MnP-driven S-glutathionylation in cortex and hippocampus showed differential responses to MnP administration and radiation in these two brain regions. A better understanding of how preserved hippocampal neurogenesis correlates with cognitive functions following cranial irradiation will be helpful in designing better MnP-based radioprotection strategies. Keywords: Mn porphyrin, Bioavailability, BMX-001, Hippocampus, Neurogenesis, Radioprotection

Mn2+ anchored CdS polymer nanocomposites: An efficient alternative for Mn2+ doped CdS nanoparticles

International Nuclear Information System (INIS)

Saikia, Bhaskar Jyoti; Nath, Bikash Chandra; Borah, Chandramika; Dolui, Swapan Kumar

2015-01-01

A chelating bi-functional polymer brushes was prepared via atom transfer radical polymerization using grafting-from methodology. Mn 2+ -anchored CdS-polymer nanocomposites were synthesized using this graft copolymer by simple chelation method resulting in emission at about 620 nm which originates from the fluorescence of manganese ions embedded on the surface of CdS nanoparticles. This method provides an efficient straightforward substitute of Mn 2+ dopped CdS nanoparticles. Optical properties of the composites were investigated which indicates that simple Mn 2+ chelation and subsequent binding of CdS in a polymer matrix can have similar effect in the luminescence property as those synthesized via complex doping methods. Moreover this methodology can be applied for synthesis of any metal anchored nanocomposites proficiently and cost effectively in large-scale production. - Highlights: • A chelating bifunctional copolymer brush was synthesized via ATRP. • CdS nanoparticles and Mn 2+ were coupled with the bifunctional polymer. • Composites showed emission properties similar to Mn 2+ doped CdS nanoparticles. • Side chain length of the polymers also affect the emission properties of the composites.

Cardiovascular effects of MnDPDP and MnCl{sub 2} in dogs with acute ischaemic heart failure

Energy Technology Data Exchange (ETDEWEB)

Karlsson, J.O.G. [Trondheim Univ. (Norway). Dept. of Physiology and Biomedical Engineering]|[Nycomed Imaging AS, Oslo (Norway). Research and Development; Mortensen, E. [Dept. of Physiology, Inst. of Medical Biology, Univ. of Tromsoe (Norway); Pedersen, H.K. [Dept. of Radiology, The National Hospital, Oslo (Norway); Sager, G. [Dept. of Pharmacology, Inst. of Medical Biology, Univ. of Tromsoe (Norway); Refsum, H. [Inst. for Experimental Medical Research, Ullevaal Hospital, Oslo Univ. (Norway)]|[Nycomed Imaging AS, Oslo (Norway). Research and Development

1997-07-01

Purpose: To examine the cardiovascular effects of MnDPDP in a model of acute heart failure in the dog, and to compare these effects with those of MnCl{sub 2}. Material and Methods: The study involved slow i.v. infusion of either 10, 60 and 300 {mu}mol/kg of MnDPDP, or 1, 6 and 30 {mu}mol/kg MnCl{sub 2}, in increasing doses to groups of 5 dogs. Acute ischaemic heart failure was first induced by injection of polystyrene microspheres (50{+-}10 {mu}m) into the left coronary artery until a stable left ventricular end-diastolic pressure of approximately 20 mm Hg was achieved. The following test parameters were measured: Left ventricular end-diastolic pressure; the first derivatives of maximum rate of left ventricular contraction and relaxation; mean aortic pressure; pulmonary artery pressure; right atrial pressure; cardiac ouput; heart rate; QT-time; PQ-time; QRS-width; and plasma catecholamines. Results: Slow infusion of MnDPDP at doses up to and including 12 times the clinical dose was well tolerated in dogs without further depression of cardiovascular function during acute ischaemic heart failure. At 300 {mu}mol/kg, i.e. 60 times the human dose, only minor haemodynamic and electrophysiological effects were seen, and these were similar to those seen after administration of 30 {mu}mol/kg MnCl{sub 2}. (orig./AJ).

Diffusion of $^{52}$Mn in GaAs

CERN Multimedia

2002-01-01

Following our previous diffusion studies performed with the modified radiotracer technique, we propose to determine the diffusion of Mn in GaAs under intrinsic conditions in a previously un-investigated temperature region. The aim of the presently proposed experiments is twofold. \\begin{itemize} \\item A quantitative study of Mn diffusion in GaAs at low Mn concentrations would be decisive in providing new information on the diffusion mechanism involved. \\item As Ga vacancies are expected to be involved in the Mn diffusion process it can be predicted that also the GaAs material growth technique most likely plays a role. To clarify this assumption diffusion experiments will be conducted for GaAs material grown by two different techniques. \\end{itemize} For such experiments we ask for two runs of 3 shifts (total of 6 shifts) with $^{52}$Mn$^{+}$ ion beam.

Synthesis of Li(x)Na(2-x)Mn2S3 and LiNaMnS2 through redox-induced ion exchange reactions

International Nuclear Information System (INIS)

Luthy, Joshua A.; Goodman, Phillip L.; Martin, Benjamin R.

2009-01-01

Na 2 Mn 2 S 3 was oxidatively deintercalated using iodine in acetonitrile to yield Na 1.3 Mn 2 S 3 , with lattice constants nearly identical to that of the reactant. Lithium was then reductively intercalated into the oxidized product to yield Li 0.7 Na 1.3 Mn 2 S 3 . When heated, this metastable compound decomposed to form a new crystalline compound, LiNaMnS 2 , along with MnS and residual Na 2 Mn 2 S 3 . Single crystal X-ray diffraction structural analysis of LiNaMnS 2 revealed that this compound crystallizes in P-3m1 with cell parameters a=4.0479(6) A, c=6.7759(14) A, V=96.15(3) A 3 (Z=1, wR2=0.0367) in the NaLiCdS 2 structure-type. - Graphical abstract: Structure of LiNaMnS 2 . Li and Mn are statistically distributed in edge-shared tetrahedral environments linked into infinite planes. Sodium ions occupy interlayer sites

Influence of S/Mn molar ratio on the morphology and optical property of γ-MnS thin films prepared by microwave hydrothermal

International Nuclear Information System (INIS)

Yu, Xin; Li-yun, Cao; Jian-feng, Huang; Jia, Liu; Jie, Fei; Chun-yan, Yao

2013-01-01

Highlights: ► The influence of the precursor solution molar ratio of S/Mn. ► The degree of orientation of the γ-MnS film decrease slightly with increasing the S/Mn from 2.0 to 4.0. ► Film quality is strongly affected by the initial nucleation. ► The absorption edge obviously shifts to a higher wavelength with the increase of the S/Mn molar ratio from 2.0 to 4.0. - Abstract: Well crystallized γ-MnS thin films were successfully synthesized at low temperature and short processing time via a novel microwave hydrothermal (M-H) process without any complexing agent by using manganese chloride and thioacetamide as source materials. The influence of different S/Mn molar ratio in the precursor solution on the phase compositions, morphologies and optical properties of the as-deposited films was investigated. The as-deposited γ-MnS thin films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–vis). Results show that the wurtzite phase γ-MnS thin films with good crystallization can be achieved when S/Mn molar ratio is controlled at 2.0–4.0. The deposited γ-MnS thin films exhibit (1 0 0) orientation growth with the thickness of 300–500 nm. With the increase of S/Mn molar ratio from 2.0 to 4.0, the orientation growth is weakened while the dense and uniform of the as-deposited γ-MnS thin films are obviously improved and the corresponding band gap of the thin films increase from 3.88 to 3.97 eV.

Replication of Annual Cycles in Mn in Hudson River Cores: Mn Peaks During High Water Flow

Science.gov (United States)

Abbott, D. H.; Hutson, D.; Marrero, A. M.; Block, K. A.; Chang, C.; Cai, Y.

2017-12-01

Using the results from an ITRAX, XRF scanner, we previously reported apparent annual cycles in Mn in a single, high sedimentation rate Hudson River core, LWB1-8, taken off Yonkers, NY (Carlson et al., 2016). We replicated these results in three more high sedimentation rate cores and found stratigraphic markers that verify our inferences about the annual nature of the Mn cycles. The three new cores are LWB4-5 taken off Peekskill, NY, and LWB3-44 and LWB3-25, both taken in Haverstraw Bay. The cores are from water depths of 7-9 meters and all have high magnetic susceptibilities (typically > 30 cgs units) in their upper 1 to 2 meters. The high susceptibilities are primarily produced by magnetite from modern industrial combustion. One core, LWB1-8, has reconnaissance Cs dates that verify the annual nature of the cycles. More Cs dates are expected before the meeting. We developed several new methods of verifying the annual nature of our layer counts. The first is looking at the grain size distribution and age of layers with unusually high Mn peaks. Peaks in Si, Ni and Ti and peaks in percentage of coarse material typically accompany the peaks in Mn. Some are visible as yellow sandy layers. The five highest peaks in Mn in LWB1-8 have layer counted ages that correspond (within 1 year in the top meter and within 2 years in the bottom meter) to 1996, 1948, 1913, 1857 and 1790. The latter three events are the three largest historical spring freshets on the Hudson. 1996 is a year of unusually high flow rate during the spring freshet. Based on our work and previous work on Mn cycling in rivers, we infer that the peaks in Mn are produced by extreme erosional events that erode sediment and release pore water Mn into the water column. The other methods of testing our chronology involve marine storms that increase Ca and Sr and a search for fragments of the Peekskill meteorite that fell in October 1992. More information on the latter will be available by the meeting.

Enhancement of electrochemical performance of LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 by surface modification with MnO_2

International Nuclear Information System (INIS)

Guo, Xin; Cong, Li-Na; Zhao, Qin; Tai, Ling-Hua; Wu, Xing-Long; Zhang, Jing-Ping; Wang, Rong-Shun; Xie, Hai-Ming; Sun, Li-Qun

2015-01-01

LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 is successfully coated with MnO_2 by a chemical deposition method. The X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) results demonstrate that MnO_2 forms a thin layer on the surface of LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 without destroying the crystal structure of the core material. Compared with pristine LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2, the MnO_2-coated sample shows enhanced electrochemical performance especially the rate capability. Even at a current density of 750 mA g"−"1, the discharge capacity of MnO_2-coated LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 is 155.15 mAh g"−"1, while that of the pristine electrode is only 132.84 mAh g"−"1 in the range of 2.5–4.5 V. The cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) curves show that the MnO_2 coating layer reacts with Li"+ during cycling, which is responsible for the higher discharge capacity of MnO_2-coated LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2. Electrochemical impedance spectroscopy (EIS) results confirmed that the MnO_2 coating layer plays an important role in reducing the charge transfer resistance on the electrolyte–electrode interfaces. - Highlights: • MnO_2 coated LiNi_1_/_3Co_1_/_3Mn_1_/_3O_2 cathode material is synthesized for the first time. • MnO_2 offers available sites for insertion of extracted lithium. • The preserved surface and crystal structures results in the improved kinetics.

Preparation and properties of a monomeric Mn(IV)-oxo complex.

Science.gov (United States)

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.

IMPROVED log(gf ) VALUES OF SELECTED LINES IN Mn I AND Mn II FOR ABUNDANCE DETERMINATIONS IN FGK DWARFS AND GIANTS

International Nuclear Information System (INIS)

Den Hartog, E. A.; Lawler, J. E.; Sobeck, J. S.; Sneden, C.; Cowan, J. J.

2011-01-01

The goal of the present work is to produce transition probabilities with very low uncertainties for a selected set of multiplets of Mn I and Mn II. Multiplets are chosen based upon their suitability for stellar abundance analysis. We report on new radiative lifetime measurements for 22 levels of Mn I from the e 8 D, z 6 P, z 6 D, z 4 F, e 8 S, and e 6 S terms and six levels of Mn II from the z 5 P and z 7 P terms using time-resolved laser-induced fluorescence on a slow atom/ion beam. New branching fractions for transitions from these levels, measured using a Fourier-transform spectrometer, are reported. When combined, these measurements yield transition probabilities for 47 transitions of Mn I and 15 transitions of Mn II. Comparisons are made to data from the literature and to Russell-Saunders (LS) theory. In keeping with the goal of producing a set of transition probabilities with the highest possible accuracy and precision, we recommend a weighted mean result incorporating our measurements on Mn I and II as well as independent measurements or calculations that we view as reliable and of a quality similar to ours. In a forthcoming paper, these Mn I/II transition probability data will be utilized to derive the Mn abundance in stars with spectra from both space-based and ground-based facilities over a 4000 A wavelength range. With the employment of a local thermodynamic equilibrium line transfer code, the Mn I/II ionization balance will be determined for stars of different evolutionary states.

Effects of dopant ion and Mn valence state in the La{sub 1-x}A{sub x}MnO{sub 3} (A=Sr,Ba) colossal magnetoresistance films

Energy Technology Data Exchange (ETDEWEB)

Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyung-Ho; Hong, MunPyo; Kwon, Kwang-Ho [Department of Materials Science and Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-ku, Seoul 120-749 (Korea, Republic of); Department of Display and Semiconductor Physics, Korea University, Jochiwon, Chungnam 339-700 (Korea, Republic of); Department of Control and Instrumentation Engineering, Korea University, Jochiwon, Chungnam 339-700 (Korea, Republic of)

2010-01-15

The structural and electrical properties of Mn-based colossal magnetoresistance (CMR) thin films with controlled tolerance factor and Mn ion valance ratio were studied using crystal structure and chemical bonding character analyses. La{sub 0.7}Sr{sub 0.3}MnO{sub 3}, La{sub 0.7}Ba{sub 0.3}MnO{sub 3}, and La{sub 0.82}Ba{sub 0.18}MnO{sub 3} thin films with different contents of divalent cations and Mn{sup 3+}/Mn{sup 4+} ratios were deposited on amorphous SiO{sub 2}/Si substrate by rf magnetron sputtering at a substrate temperature of 350 deg. C. The films showed the same crystalline structure as the pseudocubic structure. The change in the sheet resistance of films was analyzed according to strain state of the unit cell, chemical bonding character of Mn-O, and Mn{sup 3+}/Mn{sup 4+} ratio controlling the Mn{sup 3+}-O{sup 2-}-Mn{sup 4+} conducting path. Mn L-edge x-ray absorption spectra revealed that the Mn{sup 3+}/Mn{sup 4+} ratio changed according to different compositions of Sr or Ba and the Mn 2p core level x-ray photoelectron spectra showed that the Mn 2p binding energy was affected by the covalence of the Mn-O bond and Mn{sup 3+}/Mn{sup 4+} ratio. In addition, O K-edge x-ray absorption spectra showed covalently mixed Mn 3d and O 2p states and matched well with the resistivity changes of CMR films. Temperature coefficient of resistance values were obtained at approximately -2.16%/K to -2.46%/K of the CMR films and were correct for infrared sensor applications.

Ferri-magnetic order in Mn induced spinel Co_3_−_xMn_xO_4 (0.1≤x≤1.0) ceramic compositions

International Nuclear Information System (INIS)

Meena, P.L.; Sreenivas, K.; Singh, M.R.; Kumar, Ashok; Singh, S.P.; Kumar, Ravi

2016-01-01

We report structural and magnetic properties of spinel Co_3_−_xMn_xO_4 (x=0.1–1.0) synthesized by solid state reaction technique. Rietveld refinement analysis of X-ray diffraction (XRD) data, revealed the formation of polycrystalline single phase Co_3_−_xMn_xO_4 without any significant structural change in cubic crystal symmetry with Mn substitution, except change in lattice parameter. Temperature dependent magnetization data show changes in magnetic ordering temperature, indicating formation of antiferromagnetic (AFM) and ferrimagnetic (FM) phase at low Mn concentration (x≤0.3) and well-defined FM phase at high Mn concentration (x≥0.5). The isothermal magnetization records established an AFM/FM mixed phase for composition ranging 0.1 0.5. - Highlights: • Synthesis of single phase polycrystalline Co_3_−_xMn_xO_4 ceramic. • Change in magnetic ordering with varying Mn concentration. • The complex spin distribution is contributing to FM ordering with higher Mn.

The novel eutectic microstructures of Si-Mn-P ternary alloy

International Nuclear Information System (INIS)

Wu Yaping; Liu Xiangfa

2010-01-01

The microstructures of Si-Mn-P alloy manufactured by the technique of combining phosphorus transportation and alloy melting were investigated using electron probe micro-analyzer (EPMA). The phase compositions were determined by energy spectrum and the varieties of eutectic morphologies were discussed. It is found that there is no ternary compound but Si, MnP and MnSi 1.75-x could appear when the Si-Mn-P alloy's composition is proper. Microstructure is greatly refined by rapid solidification technique and the amount of eutectic phases change with faster cooling rates. Moreover, primary Si or MnP are surrounded firstly by the binary eutectic (Si + MnP) and then the ternary eutectic (Si + MnSi 1.75-x + MnP) which also exhibit binary structures due to divorced eutectic determined by the particularity of some Si-Mn-P alloys.

Lesson study in prospective mathematics teacher education: didactic and paradidactic technology in the post-lesson reflection

DEFF Research Database (Denmark)

Rasmussen, Klaus

2016-01-01

This paper presents a detailed analysis of the post-lesson reflection, carried out in the context of eight cases of lesson study conducted by teams of Danish, lower secondaryprospective teachers and their supervisors. The participants, representing different institutions, were all new to the less...... and concern to the whole profession of mathematics teachers and the analysis adds to our insight into the potential of lesson study in prospective education as a meeting place where pertinent actors contribute to the expansion and dissemination of shared professional knowledge......This paper presents a detailed analysis of the post-lesson reflection, carried out in the context of eight cases of lesson study conducted by teams of Danish, lower secondaryprospective teachers and their supervisors. The participants, representing different institutions, were all new to the lesson...... study format. Nevertheless, it is demonstrated how their interaction shape the development of discourse about mathematical learning. The anthropological theory of the didactic is employed as the theoretical approach to analyse the mathematical and primarily didactical praxeologies developed...

Moessbauer study of Mn-Zn and Mn ferrites prepared by wet method

International Nuclear Information System (INIS)

Michalk, C.

1985-01-01

Moessbauer spectroscopy was employed to study Mn-Zn ferrites before and after low-temperature annealing. The unannealed Mn-Zn ferrite prepared by a wet method and also the sintered material after annealing at 400 deg C in air show the presence of paramagnetic clusters. These findings are explained as being due to nonrandom ordering of Fe 3+ and Zn 2+ ions caused by local charge compensation in the neighbourhood of cation vacancies. A change of cation distribution after annealing at relatively low temperatures was observed. 10 refs., 3 figs. (author)

Exchange interaction in MnPt/FeCo sputtered multilayers

International Nuclear Information System (INIS)

Honda, S.; Nawate, M.; Norikane, T.

2000-01-01

MnPt single-layer films have been prepared on glass substrates by RF magnetron sputtering for studying the composition dependencies of resistivity and crystalline structure. In the as-deposited state, the resistivity increases with Mn content and reaches the maximum at 69 at%. By annealing, the resistivity of the films having the Mn content around 51 at% increases, closely relating to the growth of the ordered CuAu FCT-type MnPt crystals. For the both film structures of the glass/Cu/FeCo/MnPt/Cu and the glass/MnPt/FeCo/Cu, which have been sputter-deposited on glass substrates, the exchange interaction between MnPt and FeCo layers, and the coercivity of the FeCo layer have been examined as functions of the Mn content, the layer thickness and the annealing temperature. In the as-deposited state, the exchange field (H ex ) is nearly zero up to 75 at% of Mn content, above which the value of H ex increases and shows the maximum at 85 at%, in which the blocking temperature is about 100 deg. C. By annealing, the value of H ex increases for the films of Mn content around 40-60 at%, exhibiting the higher blocking temperature than 360 deg. C. The temperature stability has also been examined using the Rutherford backscattering spectrometry

A facile synthesis of α-MnO2 used as a supercapacitor electrode material: The influence of the Mn-based precursor solutions on the electrochemical performance

Science.gov (United States)

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.

Metal-semiconductor transition at a comparable resistivity level and positive magnetoresistance in Mn3Mn1-x Pd x N thin films

Science.gov (United States)

Xu, T.; Ji, G. P.; Cao, Z. X.; Ji, A. L.

2018-02-01

Thin films of antiperovskite Mn3Mn1-x Pd x N with x up to 0.36 were grown by reactive magnetron co-sputtering method. All the deposits exhibit a [1 0 0] preferential orientation, with the lattice constant slightly enlarged in samples with ever more Pd atoms partially substituting the MnI atoms in Mn3MnN matrix. The replacement of MnI atoms in antiperovskite structure by Pd atoms, besides reducing the saturation magnetization, also invokes a metal-semiconductor transition which occurs remarkably at a comparable resistivity level. Moreover, a positive magnetoresistance was observed in samples of a high Pd content. These tunable electrical and magnetic properties of ternary antiperovskite compounds might promise some ingenious applications in electronic industry.

Outline of High School Credit Courses.

Science.gov (United States)

South Carolina State Dept. of Education, Columbia.

An outline is presented of the objectives and content of courses offered for credit in high schools in South Carolina. Courses in the following subjects are described: (1) art; (2) drama; (3) driver education; (4) environmental education; (5) foreign language: French, German, Russian, Spanish; (6) health; (7) language arts; (8) mathematics; (9)…

The Fe/Mn constraint on precursors of basaltic achondrites

Science.gov (United States)

Delaney, Jeremy S.; Boesenberg, Joseph S.

1993-01-01

Most achondritic meteorites have Fe/Mn ratios that are lower than those of carbonaceous chondrites and of course are lower than the solar system abundance ratio of these elements. Models of the origin of achondritic assemblages must, therefore, account for these ratios. Fe/Mn ratios are suggested to be distinctive for samples from each achondrite parent body and for the Earth and Moon, but the correspondence between the Fe/Mn systematics of achondrites and chondritic precursors is unclear. Most models of achondrite genesis involve magmatic differentiation of chondritic precursors. The Fe/Mn difference between achondrites and chondrites is particularly significant since Fe and Mn are geochemically similar elements with similar partitioning behavior in familiar magmatic systems and are generally coupled during crystal-liquid fractionation. In contrast, however, Mn is more volatile than Fe in a nebular setting. Variation of Fe/Mn ratios based on the relative volatility of these elements in the early nebula provides a constraint for models by which the basaltic achondrites (with Fe/Mn ratios approximately = 25-50) are derived from mixtures of nebular components that were enriched in volatile components such as Mn. However, such volatile enriched components have not been identified in chondrites. When the abundance in achondrites of elements of similar volatility is examined, anomalies appear. For example, Na is massively depleted in basaltic achondrites when compared to Mn. These anomalies might be explained using current models but the alternative hypothesis, that Fe/Mn ratio is controlled not by nebular volatility constraints, but by planetary differentiation should be explored.

Spin properties of charged Mn-doped quantum dota)

Science.gov (United States)

Besombes, L.; Léger, Y.; Maingault, L.; Mariette, H.

2007-04-01

The optical properties of individual quantum dots doped with a single Mn atom and charged with a single carrier are analyzed. The emission of the neutral, negatively and positively charged excitons coupled with a single magnetic atom (Mn) are observed in the same individual quantum dot. The spectrum of the charged excitons in interaction with the Mn atom shows a rich pattern attributed to a strong anisotropy of the hole-Mn exchange interaction slightly perturbed by a small valence-band mixing. The anisotropy in the exchange interaction between a single magnetic atom and a single hole is revealed by comparing the emission of a charged Mn-doped quantum dot in longitudinal and transverse magnetic field.

Neutron diffraction study of the magnetic structures of CeMn2Ge2 and CeMn2Si2

International Nuclear Information System (INIS)

Fernandez-Baca, J.A.; Chakoumakos, B.C.; Hill, P.; Ali, N.

1995-01-01

The magnetic properties of the layered compounds of the form RMn 2 X 2 (R = Rare Earth, X = Si, Ge) have been thought to be sensitive to the intralayer Mn-Mn distance. Thus it has been reported that the Mn moments in CeMn 2 Si 2 are aligned antiferromagnetically (AF) below T N = 380K, while the Mn moments in CeMn 2 Ge 2 are ferromagnetic (FM) below T C = 316K. Recently, however, there has been some debate about the actual magnetic structures of this family of compounds, and for this reason the authors have performed high-resolution neutron powder diffraction measurements on these compounds for temperatures between 12K and 550K. The measurements indicate that at high temperatures both compounds are paramagnetic. Below T N = 380K CeMn 2 Si 2 becomes a collinear AF, with a structure similar to that reported by Siek et al. in which the magnetic propagation vector is τ = (0 0 1). CeMn 2 Ge 2 on the other hand, exhibits two different magnetic transitions. At T N ∼ 415K there is a transition to a collinear AF phase characterized by the commensurate propagation wavevector τ = (1 0 1). At T C = 318K there is a transition to a conical structure with a ferromagnetic component along the c-axis and a helical component in the ab plane. The helical component is characterized by the incommensurate propagation vector τ = (1 0 1-q z ), where q z is temperature dependent. These findings are consistent with the recent results of Welter et al

Tuning the magnetic interactions in GaAs:Mn/MnAs hybrid structures by controlling shape and position of MnAs nanoclusters

Energy Technology Data Exchange (ETDEWEB)

Elm, Matthias Thomas

2010-07-01

In this work the magnetic properties of hexagonal MnAs nanoclusters and their influence on the transport properties of GaAs:Mn /MnAs hybrid structures were studied. Various arrangements of isolated nanoclusters and cluster chains were grown on (111)B-GaAs substrates by SA-MOVPE. The first part of this work deals with the manufacturing process of the different cluster arrangements investigated. By a suitable pre-structuring of the substrate it was possible to influence the cluster size, cluster shape and cluster position systematically. Preparing various arrangements it could be shown that the hexagonal nanoclusters prefer to grow along their a-axes. In the second part, the magnetic properties of the nanoclusters were studied. Ferromagnetic resonance (FMR) measurements show a hard magnetic axis perpendicular to the sample plane, i.e. parallel to the c-axis. By measurements, where the magnetic field was rotated in the sample plane, it could be demonstrated that the orientation of the magnetization can be forced into a certain direction by controlling the cluster shape. These results are confirmed by measurements using magnetic force microscopy. The third part deals with the influence of the nanoclusters and their arrangement on the transport properties of the GaAs:Mn matrix. For temperatures above 30 K the structures investigated show positive as well as negative magnetoresistance effects, which are typical for granular GaAs:Mn/MnAs hybrid structures. This behaviour can be explained in the context of transport in extended band states. The size of the magnetoresistance effects correlates strongly with the respective cluster arrangement of the sample. This behaviour has been predicted theoretically and could be confirmed experimentally in the context of this work. Below 30 K large positive magnetoresistance effects show up for the regular cluster arrangements, which cannot be observed for hybrid structures with random cluster distributions. These large positive

Versatility of MnO2 for lithium battery applications

CSIR Research Space (South Africa)

Thackeray, MM

1993-03-15

Full Text Available , layered-MnO2, spinel-related Li2O.yMnO2 (y > = 2.5) and ramsdellite-MnO2 materials. An attempt has been made to clarify issues relating to the structural features of 'CDMO'-type materials that are prepared by the reaction of gamma-MnO2 with LiNO3 (or Li...

Luminescence in colloidal Mn2+-doped semiconductor nanocrystals

International Nuclear Information System (INIS)

Beaulac, Remi; Archer, Paul I.; Gamelin, Daniel R.

2008-01-01

Recent advances in nanocrystal doping chemistries have substantially broadened the variety of photophysical properties that can be observed in colloidal Mn 2+ -doped semiconductor nanocrystals. A brief overview is provided, focusing on Mn 2+ -doped II-VI semiconductor nanocrystals prepared by direct chemical synthesis and capped with coordinating surface ligands. These Mn 2+ -doped semiconductor nanocrystals are organized into three major groups according to the location of various Mn 2+ -related excited states relative to the energy gap of the host semiconductor nanocrystals. The positioning of these excited states gives rise to three distinct relaxation scenarios following photoexcitation. A brief outlook on future research directions is provided. - Graphical abstract: Mn 2+ -doped semiconductor nanocrystals are organized into three major groups according to the location of various Mn 2+ -related excited states relative to the energy gap of the host semiconductor nanocrystals. The positioning of these excited states gives rise to three distinct relaxation scenarios following photoexcitation

Interplay between localization and magnetism in (Ga,Mn)As and (In,Mn)As

OpenAIRE

Yuan, Ye; Xu, Chi; Hübner, René; Jakiela, Rafal; Böttger, Roman; Helm, Manfred; Sawicki, Maciej; Dietl, Tomasz; Zhou, Shengqiang

2017-01-01

Ion implantation of Mn combined with pulsed laser melting is employed to obtain two representative compounds of dilute ferromagnetic semiconductors (DFSs): Ga1-xMnxAs and In1-xMnxAs. In contrast to films deposited by the widely used molecular beam epitaxy, neither Mn interstitials nor As antisites are present in samples prepared by the method employed here. Under these conditions the influence of localization on the hole-mediated ferromagnetism is examined in two DFSs with a differing strengt...

Ant-cave structured MnCO3/Mn3O4 microcubes by biopolymer-assisted facile synthesis for high-performance pseudocapacitors

Science.gov (United States)

Chandra Sekhar, S.; Nagaraju, Goli; Yu, Jae Su

2018-03-01

Porous and ant-cave structured MnCO3/Mn3O4 microcubes (MCs) were facilely synthesized via a biopolymer-assisted hydrothermal approach. Herein, chitosan was used as a natural biopolymer, which greatly controls the surface morphology and size of the prepared composite. The amino and hydroxyl group-functionalized chitosan engraves the outer surface of MCs during the hydrothermal process, which designs the interesting morphology of nanopath ways on the surface of MCs. When used as an electrode material for pseudocapacitors, the ant-cave structured MnCO3/Mn3O4 MCs showed superior energy storage values compared to the material prepared without chitosan in aqueous electrolyte solution. Precisely, the prepared ant-cave structured MnCO3/Mn3O4 MCs exhibited a maximum specific capacitance of 116.2 F/g at a current density of 0.7 A/g with an excellent cycling stability of 73.86% after 2000 cycles. Such facile and low-cost synthesis of pseudocapacitive materials with porous nanopaths is favorable for the fabrication of high-performance energy storage devices.

Acute stroke: automatic perfusion lesion outlining using level sets.

Science.gov (United States)

Mouridsen, Kim; Nagenthiraja, Kartheeban; Jónsdóttir, Kristjana Ýr; Ribe, Lars R; Neumann, Anders B; Hjort, Niels; Østergaard, Leif

2013-11-01

To develop a user-independent algorithm for the delineation of hypoperfused tissue on perfusion-weighted images and evaluate its performance relative to a standard threshold method in simulated data, as well as in acute stroke patients. The study was approved by the local ethics committee, and patients gave written informed consent prior to their inclusion in the study. The algorithm identifies hypoperfused tissue in mean transit time maps by simultaneously minimizing the mean square error between individual and mean perfusion values inside and outside a smooth boundary. In 14 acute stroke patients, volumetric agreement between automated outlines and manual outlines determined in consensus among four neuroradiologists was assessed with Bland-Altman analysis, while spatial agreement was quantified by using lesion overlap relative to mean lesion volume (Dice coefficient). Performance improvement relative to a standard threshold approach was tested with the Wilcoxon signed rank test. The mean difference in lesion volume between automated outlines and manual outlines was -9.0 mL ± 44.5 (standard deviation). The lowest mean volume difference for the threshold approach was -25.8 mL ± 88.2. A significantly higher Dice coefficient was observed with the algorithm (0.71; interquartile range [IQR], 0.42-0.75) compared with the threshold approach (0.50; IQR, 0.27- 0.57; P , .001). The corresponding agreement among experts was 0.79 (IQR, 0.69-0.83). The perfusion lesions outlined by the automated algorithm agreed well with those defined manually in consensus by four experts and were superior to those obtained by using the standard threshold approach. This user-independent algorithm may improve the assessment of perfusion images as part of acute stroke treatment. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13121622/-/DC1. RSNA, 2013

On the state of Mn in Mn{sub x}Zn{sub 1−x}O nanoparticles and their surface modification with isonipecotic acid

Energy Technology Data Exchange (ETDEWEB)

Jiménez-Hernández, L.; Estévez-Hernández, O. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología de Avanzada, Unidad Legaria, Ciudad México, México (Mexico); Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana (Cuba); Hernández, M.P. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana (Cuba); Universidad Nacional Autónoma de México (UNAM), Centro de Nanociencias y Nanotecnología (CNyN), Ensenada, Baja California, México (Mexico); Díaz, J.A.; Farías, M.F. [Universidad Nacional Autónoma de México (UNAM), Centro de Nanociencias y Nanotecnología (CNyN), Ensenada, Baja California, México (Mexico); Reguera, E., E-mail: edilso.reguera@gmail.com [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología de Avanzada, Unidad Legaria, Ciudad México, México (Mexico)

2017-03-15

Mn-doped ZnO (Mn{sub x}Zn{sub 1−x}O) nanoparticles were synthesized by the co-precipitation method and coated with isonipecotic acid as capping ligand. The structure, composition and morphology of the resulting nanomaterial were investigated by energy disperse X-ray analysis, X-ray diffraction, and transmission electron microscopy data. Such measurements showed that the solid obtained contains 6 at% of Mn and it is formed by a highly crystalline material with 3–5 nm range of crystallite size, and only a small elongation of its cell parameter with respect to undoped ZnO wurtzite unit cell. Information on the state of manganese atom in the Mn{sub x}Zn{sub 1−x}O nanostructures formed was obtained from X-ray photoelectron (XPS) and electron energy loss (EELS) spectroscopies. XPS and EELS spectra are composed of four peaks, corresponding to two species of Mn(II) and signals from Mn(III) and Mn(IV). Such spectral data on the state of Mn in the material studied is consistent with the mapping of Mn distribution observed in recorded transmission electron microscopy images, which reveal presence of clusters of Mn atoms. Only a fraction of doping Mn atoms were found forming a solid solution with the host ZnO structure. The functionalization of the nanoparticles system with Isonipecotic acid shows that this molecule remains anchored to the nanoparticles surface mainly through its N basic site. The availability of free carboxylate groups in the capping molecule was tested by conjugation to type IV horseradish peroxidase. - Graphical abstract: State of Mn atoms in Mn-doped ZnO nanostructures prepared by the precipitation method, their capping with isonipecotic acid and subsequent conjugation to peroxidase. - Highlights: • State of manganese in manganese-doped zinc oxide nanoparticles. • Isonipecotic acid as surface modifier of ZnO nanoparticles. • Peroxidase conjugation to ZnO nanoparticles modified with isonipecotic acid.

Direct Demonstration of the Emergent Magnetism Resulting from the Multivalence Mn in a LaMnO3 Epitaxial Thin Film System

DEFF Research Database (Denmark)

Niu, Wei; Liu, Wenqing; Gu, Min

2018-01-01

that play a decisive role in the emergence of ferromagnetism in the otherwise antiferromagnetic LaMnO3 thin films are found. Combining spatially resolved electron energy‐loss spectroscopy, X‐ray absorption spectroscopy, and X‐ray magnetic circular dichroism techniques, it is determined unambiguously...... provide a hitherto‐unexplored multivalence state of Mn on the emergent magnetism in undoped manganite epitaxial thin films, such as LaMnO3 and BiMnO3, and shed new light on all‐oxide spintronic devices....

Room Temperature Ferromagnetic Mn:Ge(001

Directory of Open Access Journals (Sweden)

George Adrian Lungu

2013-12-01

Full Text Available We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001, heated at relatively high temperature (starting with 250 °C. The samples were characterized by low energy electron diffraction (LEED, scanning tunneling microscopy (STM, high resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, superconducting quantum interference device (SQUID, and magneto-optical Kerr effect (MOKE. Samples deposited at relatively elevated temperature (350 °C exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001 crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001. The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.

Local Structure of Mn in (La1-xHox)2/3Ca1/3MnO3 Studied by X-ray Absorption Fine Structure

International Nuclear Information System (INIS)

Pietnoczka, A.; Bacewicz, R.; Antonowicz, J.; Zalewski, W.; Pekala, M.; Drozd, V.; Fagnard, J.F.; Vanderbemden, P.

2010-01-01

Results of X-ray absorption fine structure measurements in manganites (La 1-x Ho x ) 2/3 Ca 1/3 MnO 3 with 0.15 3 is doped with a divalent element such as Ca 2+ , substituting for La 3+ , holes are induced in the filled Mn d orbitals. This leads to a strong ferromagnetic coupling between Mn sites. Ca ions in La 1-x Ca x MnO 3 introduce a distortion of the crystal lattice and mixed valence Mn ions (Mn 3+ and Mn 4+ ). On the other hand, in manganites (La 1-x Ho x ) 2/3 Ca 1/3 MnO 3 the substitution of La for Ho causes a lattice distortion and induces a disorder, which reduces a magnetic interaction. The ferromagnetic transition temperature and conductivity decrease very quickly with increasing x. The magnetic and transport properties of compounds depend on the local atomic structure around Mn ions. The information on the bond lengths and Debye-Waller factor are obtained from the extended X-ray absorption fine structure (EXAFS) data analysis. The charge state of Mn is determined from the position of the absorption edge in X-ray absorption near edge structure (XANES) data. XAFS results are in good agreement with magnetic characteristics of the studied materials. (authors)

Small Business Management. Part I, A Suggested Course Outline.

Science.gov (United States)

New York State Education Dept., Albany. Bureau of Continuing Education Curriculum Development.

In this curriculum guide on small business management, lessons (including specific course content and teaching suggestions) are developed around general traits and practices conducive to success in small businesses, loans and other sources of capital, budgeting and planning, recordkeeping, marketing and selling, advertising and sales promotion,…

Binding of higher alcohols onto Mn(12) single-molecule magnets (SMMs): access to the highest barrier Mn(12) SMM.

Science.gov (United States)

Lampropoulos, Christos; Redler, Gage; Data, Saiti; Abboud, Khalil A; Hill, Stephen; Christou, George

2010-02-15

Two new members of the Mn(12) family of single-molecule magnets (SMMs), [Mn(12)O(12)(O(2)CCH(2)Bu(t))(16)(Bu(t)OH)(H(2)O)(3)].2Bu(t)OH (3.2Bu(t)OH) and [Mn(12)O(12)(O(2)CCH(2)Bu(t))(16)(C(5)H(11)OH)(4)] (4) (C(5)H(11)OH is 1-pentanol), are reported. They were synthesized from [Mn(12)O(12)(O(2)CMe)(16)(H(2)O)(4)].2MeCO(2)H.4H(2)O (1) by carboxylate substitution and crystallization from the appropriate alcohol-containing solvent. Complexes 3 and 4 are new members of the recently established [Mn(12)O(12)(O(2)CCH(2)Bu(t))(16)(solv)(4)] (solv = H(2)O, alcohols) family of SMMs. Only one bulky Bu(t)OH can be accommodated into 3, and even this causes significant distortion of the [Mn(12)O(12)] core. Variable-temperature, solid-state alternating current (AC) magnetization studies were carried out on complexes 3 and 4, and they established that both possess an S = 10 ground state spin and are SMMs. However, the magnetic behavior of the two compounds was found to be significantly different, with 4 showing out-of-phase AC peaks at higher temperatures than 3. High-frequency electron paramagnetic resonance (HFEPR) studies were carried out on single crystals of 3.2Bu(t)OH and 4, and these revealed that the axial zero-field splitting constant, D, is very different for the two compounds. Furthermore, it was established that 4 is the Mn(12) SMM with the highest kinetic barrier (U(eff)) to date. The results reveal alcohol substitution as an additional and convenient means to affect the magnetization relaxation barrier of the Mn(12) SMMs without major change to the ligation or oxidation state.

Outline of Swedish activities on LWR fuel

Energy Technology Data Exchange (ETDEWEB)

Grounes, M [Studsvik Nuclear, Nykoeping (Sweden); Roennberg, G [OKG AB (Sweden)

1997-12-01

The presentation outlines the Swedish activities on LWR fuel and considers the following issues: electricity production; performance of operating nuclear power plants; nuclear fuel cycle and waste management; research and development in nuclear field. 4 refs, 4 tabs.

Synthesis, crystal structure and electrical properties of A-site cation ordered BaErMn2O5 and BaErMn2O6

International Nuclear Information System (INIS)

Świerczek, Konrad; Klimkowicz, Alicja; Zheng, Kun; Dabrowski, Bogdan

2013-01-01

In this paper, we report on a synthesis procedure, structural and electrical properties of BaErMn 2 O 5 and BaErMn 2 O 6 , A-site double perovskites having layered arrangement of Ba and Er cations. These materials belong to a family of BaLnMn 2 O 5+δ oxides, which up to now were successfully synthesized for Ln=Y and La–Ho lanthanides. Up to our knowledge, this is the first report on the successful synthesis of BaErMn 2 O 5 and BaErMn 2 O 6 , yielding>95 wt% of the considered compounds. Structural characterization of the materials is given at room temperature, together with in situ XRD studies, performed during oxidation of BaErMn 2 O 5 in air, at elevated temperatures up to 500 °C. A complex structural behavior was observed, with oxidation process of BaErMn 2 O 5 occurring at around 300 °C. The oxidized BaErMn 2 O 6 shows a structural phase transition at about 225 °C. Results of structural studies are supported by thermogravimetric measurements of the oxidation process, performed in air, as well as reduction process, preformed in 5 vol% of H 2 in Ar. Additionally, isothermal oxidation/reduction cycles were measured at 500 °C, showing interesting properties of BaErMn 2 O 5+δ , from a point of view of oxygen storage technology. Electrical conductivity of BaErMn 2 O 5 is of the order of 10 −4 S cm −1 at room temperature and shows activated character on temperature with activation energy E a =0.30(1) eV. Positive sign of Seebeck coefficient for this material indicates holes as dominant charge carriers. Oxidized BaErMn 2 O 6 possesses much higher electrical conductivity, almost 0.2 S cm −1 at room temperature. Additional, about 10-fold increase of electrical conductivity, occurring in the vicinity of 225 °C for this material, can be associated with phase transition from charge/orbital-ordered insulator COI(CE) to paramagnetic metal PM phase. The highest conductivity for BaErMn 2 O 6 was measured near 500 °C and is almost equal to 40 S cm −1 , while

The individual teacher in lesson study collaboration

DEFF Research Database (Denmark)

Skott, Charlotte Krog; Møller, Hanne

2017-01-01

used in lesson study research. Design/methodology/approach The authors use collective case studies. By being participant observers the authors provide detailed descriptions of two selected teachers’ lived experiences of lesson study collaboration. In addition to gain first-hand insights, the authors...... in the participation of each of the two teachers during a two-year lesson study project. By comparing these shifts the authors identify significant conditions for their individual learning. Research limitations/implications Although the study is small scale, both the insights into the different ways in which teachers...... participated and the theoretical insights might be valuable for other lesson study research approaches. Practical implications This paper provides valuable insights into conditions that might influence teachers’ participation in lesson study activities, especially in cultures with little experience of lesson...

Magnetic ordering of GdMn2

International Nuclear Information System (INIS)

Ouladdiaf, B.; Ritter, C.; Ballou, R.; Deportes, J.

1999-01-01

Complete text of publication follows. GdMn 2 crystallizes in the C15 cubic Laves phase structure. Within this structure Mn atoms lie at the vertices of regular tetrahedra stacked in the diamond arrangement connected by sharing vertices, leading to a strong geometric frustration. An antiferromagnetic magnetic order sets in below T N ∼ 105 K. It gives rise to a large magnetovolume effect (ΔV/V ∼ 1%). Thermal expansion data show two anomalies at 105 K and 35 K. The second anomaly was often interpreted as the ferromagnetic ordering of Gd sublattice. Moessbauer data indicate however, that Gd sublattice orders at T N ∼ 105 K as the Mn moments. Elastic neutron scattering measurements were performed using short wavelength neutron beam (λ = 0.5 A) on D9 at ILL. No magnetic contribution to the nuclear peaks was found excluding thereby any K = [0 0 0] component. However antiferromagnetic peaks indexed by a propagation vector [2/3 2/3 0] were observed leading to a non collinear magnetic arrangement of both Mn and Gd sublattices. The results are discussed by invoking the geometric frustration associated with the Mn atomic packing and the singlet state of the Gd ions. (author)

Large Magnetic Anisotropy in HfMnP

Science.gov (United States)

Parker, David; Lamichhane, Tej; Taufour, Valentin; Masters, Morgan; Thimmaiah, Srinivasa; Bud'Ko, Ser'gey; Canfield, Paul

We present a theoretical and experimental study of two little-studied manganese phosphide ferromagnets, HfMnP and ZrMnP, with Curie temperatures above room temperature. We find an anisotropy field in HfMnP approaching 10 T - larger than that of the permanent magnet workhorse NdFeB magnets. From theory we determine the source of this anisotropy. Our results show the potential of 3d-element-based magnetic materials for magnetic applications.

External Police Oversight in Mexico: Experiences, Challenges, and Lessons Learned

Directory of Open Access Journals (Sweden)

Rubén Guzmán Sánchez

2014-11-01

Full Text Available After nearly 20 years of ‘reformist’ measures, the police in Mexico continues to be an ineffective, unreliable, and ‘far from citizen’ institution. The efforts made so far have faded amongst political interests and agendas; multidimensional frameworks out-dated at both conceptual and interagency levels; short-sighted competition for resources; evaluation and performance monitors that are handicapped by bureaucratic inaction; and weak transparency and accountability that perpetuate the opacity in which the police operate. In this context, the agenda of external police oversight is still at a rudimentary stage. However, there are several initiatives that have managed to push the issue to the frontier of new knowledge and promising practices. This paper outlines the experiences and challenges of—as well as the lessons learned by—the Institute for Security and Democracy (Insyde A.C., one of the most recognised think tanks in Mexico.

What Happens at the Lesson Start?

Science.gov (United States)

Saloviita, Timo

2016-01-01

Transitional periods, such as lesson starts, are necessary steps from one activity to another, but they also compete with time for actual learning. The aim of the present study was to replicate a previous pilot study on lesson starts and explore possible disturbances. In total, 130 lesson starts in Finnish basic education in grades 1-9 were…

Electronic transport properties of nanostructured MnSi-films

Science.gov (United States)

Schroeter, D.; Steinki, N.; Scarioni, A. Fernández; Schumacher, H. W.; Süllow, S.; Menzel, D.

2018-05-01

MnSi, which crystallizes in the cubic B20 structure, shows intriguing magnetic properties involving the existence of skyrmions in the magnetic phase diagram. Bulk MnSi has been intensively investigated and thoroughly characterized, in contrast to MnSi thin film, which exhibits widely varying properties in particular with respect to electronic transport. In this situation, we have set out to reinvestigate the transport properties in MnSi thin films by means of studying nanostructure samples. In particular, Hall geometry nanostructures were produced to determine the intrinsic transport properties.

Formation of Nano-crystalline Todorokite from Biogenic Mn Oxides

Energy Technology Data Exchange (ETDEWEB)

Feng, X.; Zhu, M; Ginder-Vogel, M; Ni, C; Parikh, S; Sparks, D

2010-01-01

Todorokite, as one of three main Mn oxide phases present in oceanic Mn nodules and an active MnO{sub 6} octahedral molecular sieve (OMS), has garnered much interest; however, its formation pathway in natural systems is not fully understood. Todorokite is widely considered to form from layer structured Mn oxides with hexagonal symmetry, such as vernadite ({delta}-MnO{sub 2}), which are generally of biogenic origin. However, this geochemical process has not been documented in the environment or demonstrated in the laboratory, except for precursor phases with triclinic symmetry. Here we report on the formation of a nanoscale, todorokite-like phase from biogenic Mn oxides produced by the freshwater bacterium Pseudomonas putida strain GB-1. At long- and short-range structural scales biogenic Mn oxides were transformed to a todorokite-like phase at atmospheric pressure through refluxing. Topotactic transformation was observed during the transformation. Furthermore, the todorokite-like phases formed via refluxing had thin layers along the c* axis and a lack of c* periodicity, making the basal plane undetectable with X-ray diffraction reflection. The proposed pathway of the todorokite-like phase formation is proposed as: hexagonal biogenic Mn oxide {yields} 10-{angstrom} triclinic phyllomanganate {yields} todorokite. These observations provide evidence supporting the possible bio-related origin of natural todorokites and provide important clues for understanding the transformation of biogenic Mn oxides to other Mn oxides in the environment. Additionally this method may be a viable biosynthesis route for porous, nano-crystalline OMS materials for use in practical applications.

Room temperature ferromagnetism in Mn-doped NiO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Layek, Samar, E-mail: samarlayek@gmail.com; Verma, H.C.

2016-01-01

Mn-doped NiO nanoparticles of the series Ni{sub 1−x}Mn{sub x}O (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum. - Highlights: • Mn-doped NiO nanoparticles are prepared by a simple hydrothermal method. • Unit cell volume decreases with increasing doping concentration. • Mn-doping leads to room temperature ferromagnetism in NiO nanoparticles. • Magnetization is highest for 2% Mn-doping. • Above 2%, magnetization decreases with increasing doping.

Room temperature ferromagnetism in Mn-doped NiO nanoparticles

International Nuclear Information System (INIS)

Layek, Samar; Verma, H.C.

2016-01-01

Mn-doped NiO nanoparticles of the series Ni_1_−_xMn_xO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum. - Highlights: • Mn-doped NiO nanoparticles are prepared by a simple hydrothermal method. • Unit cell volume decreases with increasing doping concentration. • Mn-doping leads to room temperature ferromagnetism in NiO nanoparticles. • Magnetization is highest for 2% Mn-doping. • Above 2%, magnetization decreases with increasing doping.

Thermoelectric properties of a Mn substituted synthetic tetrahedrite.

Science.gov (United States)

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.

Magnetic structure of the YbMn2SbBi compound

International Nuclear Information System (INIS)

Morozkin, A.V.; Manfrinetti, P.

2011-01-01

Graphical abstract: Display Omitted Research highlights: → A neutron diffraction investigation in zero applied field of La 2 O 2 S-type YbMn 2 SbBi shows antiferromagnetic ordering below 138(3) K and ferrimagnetic ordering below 112(3) K. → Between 138 and 112 K, the magnetic structure of YbMn 2 SbBi consists of antiferromagnetically coupled ab-plane magnetic moments of the manganese atoms (D 1d magnetic point group). → Below 112(3) K, the magnetic structure of YbMn 2 SbBi becames the sum antiferromagnetic component with D 1d magnetic point group and ferromagnetic one with C 2 magnetic point group. → The magnitude of Yb and Mn magnetic moments in YbMn 2 SbBi at 2 K (M Yb = 3.6(2) μ B , M Mn = 3.5(2) μ B ) correspond to the trivalent state of the Yb ions and tetravalent state of the Mn ions. - Abstract: A neutron diffraction investigation has been carried out on the trigonal La 2 O 2 S-type (hP5, space group P3-bar ml, No. 164; also CaAl 2 Si 2 -type) YbMn 2 SbBi intermetallic compound. The YbMn 2 SbBi presents antiferromagnetic ordering below 138(3) K and ferrimagnetic ordering below 112(3) K. Between 138 and 112 K, the magnetic structure of YbMn 2 SbBi consists of antiferromagnetically coupled ab-plane magnetic moments of the manganese atoms (D 1d magnetic point group). Below 112(3) K, the ferromagnetic components of Yb and Mn begin to develop, and the magnetic structure of YbMn 2 SbBi becames the sum antiferromagnetic component with D 1d magnetic point group and ferromagnetic one with C 2 magnetic point group. The magnitude of Yb and Mn magnetic moments in YbMn 2 SbBi at 2 K (M Yb = 3.6(2) μ B , M Mn = 3.5(2) μ B ) correspond to the trivalent state of the Yb ions and tetravalent state of the Mn ions.

Lesson study i Danmark?

DEFF Research Database (Denmark)

Mogensen, Arne

2009-01-01

Der beskrives et japansk lesson study forløb, og det diskuteres i hvilket omfang, de gode japanske erfaringer kan overføres til dansk matematikundervisning.......Der beskrives et japansk lesson study forløb, og det diskuteres i hvilket omfang, de gode japanske erfaringer kan overføres til dansk matematikundervisning....

Validation techniques for object-oriented proof outlines

NARCIS (Netherlands)

Pierik, C.

2006-01-01

This thesis presents a proof outline logic for a simple object-oriented programming language. The language has all object-oriented features of popular programming languages like Java and C#. In particular, it supports inheritance, field shadowing, aliasing, dynamic object creation, subtype

Structural and magnetic properties of Mn nanoparticles prepared by arc-discharge

International Nuclear Information System (INIS)

Si, P.Z.; Brueck, E.; Zhang, Z.D.; Tegus, O.; Zhang, W.S.; Buschow, K.H.J.; KlAsse, J.C.P.

2005-01-01

Mn nanoparticles are prepared by arc discharge technique. MnO, α-Mn, β-Mn, and γ-Mn are detected by X-ray diffraction, while the presence of Mn 3 O 4 and MnO 2 is revealed by X-ray photoelectron spectroscopy. Transmission electron microscopy observations show that most of the Mn nanoparticles have irregular shapes, rough surfaces and a shell/core structure, with sizes ranging from several nanometers to 80 nm. The magnetic properties of the Mn nanoparticles are investigated between 2 and 350 K at magnetic fields up to 5 T. A magnetic transition occurring near 43 K is attributed to the formation of the ferrimagnetic Mn 3 O 4 . The coercivity of the Mn nanoparticles, arising mainly from Mn 3 O 4 , decreases linearly with increasing temperature below 40 K. Below the blocking temperature T B ∼ 34 K, the hysteresis loops exhibit large coercivity (up to 500 kA/m), owing to finite size effects, and irreversibility in the loops is found up to 4 T, and magnetization is not saturated up to 5 T. The relationship between structure and the magnetic properties are discussed

Structure and properties of Mn4Cl9: An antiferromagnetic binary hyperhalogen

Science.gov (United States)

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.

Phase relationships in the Er-Mn-Ti ternary system at 773 K

International Nuclear Information System (INIS)

Liu Jingqi; Wang Xina; Tang Mengqi; Su Kunpeng; Yang Xiaomao; Li Chunhui; Li Xueqiang

2009-01-01

The Phase relationship in the Er-Mn-Ti ternary system at 773 K has been investigated by X-ray powder diffraction analysis with the aid of differential thermal analysis and optical microanalysis techniques in this work. The existence of eight binary compounds Mn 15 Ti 85, αMnTi, βMnTi, Mn 2 Ti, Mn 5 Ti, ErMn 12, Er 6 Mn 23 and ErMn 2 has been confirmed at 773 K in this system. The maximum solid solubility of Ti in Mn is about 8 at%Ti. The homogeneity range of Mn 2 Ti extends from about 31 at% to 39 at% Ti. The maximum solid solubility of Er in Mn 2 Ti phase is about less than 1 at% Er. No ternary compounds were found in this ternary system at 773K. At 773 K, the isothermal section of phase diagram of Er-Mn-Ti ternary system consists of 11 single-phase regions, 19 two-phase regions and 9 three-phase regions.

Magnetic behavior of Co–Mn co-doped ZnO nanoparticles

International Nuclear Information System (INIS)

Li, Hengda; Liu, Xinzhong; Zheng, Zhigong

2014-01-01

Here, we report on systematic studies of the magnetic properties of Co and Mn co-doped ZnO nanoparticles prepared by a sol–gel technique. The effect of the concentration of the doping ions on the magnetic properties of Co and Mn co-doped ZnO nanoparticles is presented. X-ray diffraction characterizations (XRD) of co-doped ZnO nanoparticles are all wurtzite structure. The Zn 0.96 Co 0.02 Mn 0.02 O nanoparticles and Zn 0.94 Co 0.02 Mn 0.04 O nanoparticles display ferromagnetic behavior at room temperature. Superconducting quantum interference device (SQUID) magnetometer figures show that with the concentration of the Mn ions increased, the saturation magnetic moment (M s ) increased, and the magnetic is probably due to the co-doping of the Mn ions. Our results demonstrate that the Mn ions doping concentration play an important role in the ferromagnetic properties of Co–Mn co-doped ZnO nanoparticles at room temperature. - Highlights: • The effect of the doping ions on the magnetic properties is presented. • The magnetic is probably due to the co-doping of the Mn ions. • The Mn ions concentration play an important role in the ferromagnetic properties

Physical investigations on NiMn{sub 2}O{sub 4} sprayed magnetic spinel for sensitivity applications

Energy Technology Data Exchange (ETDEWEB)

Larbi, T.; Amara, A.; Ouni, B. [Unité de physique des dispositifs a semi-conducteurs, Faculté des sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Inoubli, A. [Faculté des Sciences de Bizerte Laboratoire de Physique des Matériaux Département de Physique, Zarzouna, 7021 Bizerte (Tunisia); Karyaoui, M. [Laboratoire de photovoltaïque, Centre de Recherches et des Technologies de l’Énergie, Technopole de Borj-Cédria BP 95, 2050 Hammam-Lif (Tunisia); Yumak, A. [Physics Department, Faculty of Arts and Sciences, Marmara University, Göztepe, 34722 Istanbul (Turkey); Saadallah, F. [Phothermal laboratory IPEIN, Mrezka, BP 62, 8000 Nabeul (Tunisia); Boubaker, K., E-mail: mmbb11112000@yahoo.fr [Unité de physique des dispositifs a semi-conducteurs, Faculté des sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Amlouk, M. [Unité de physique des dispositifs a semi-conducteurs, Faculté des sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia)

2015-08-01

NiMn{sub 2}O{sub 4} ternary nickel manganese oxide thin films spinels have been grown on glass substrates at 350 °C through spray pyrolysis technique. X-ray diffraction and Raman spectroscopy analyses show that the synthesized film has mainly cubic spinel structure with a preferred orientation along (111) plane. Some optical constants such as the refractive index (n), extinction coefficient (k), Urbach energy (E{sub U}=342 eV) and optical energy band gap (E{sub g}=1.07 eV) have been calculated from reflection-transmission spectra. The mirage effect technique has been used to estimate the thermal conductivity (K{sub c}). Its value is K{sub c}=25 W m{sup −1} K{sup −1}. The real part of the ac the conductivity behaviour has been investigated in the frequency range 100 Hz to 1 MHz. It was found that the real conductivity follows a power law (Aω{sup s}). The dc conductivity has been studied in the temperature range from 250 °C to 375 °C and supports the variable range hopping model proposed by Mott. The activation energy value estimated from the relaxation frequency is Ea~0.32 eV. Moreover, the temperature dependency of the resistance indicates that conduction was well described by a variable range hopping model, in which electron transfer takes place between Mn{sup 3+} and Mn{sup 4+} ions. - Highlights: • The nickel manganese oxide (NiMn{sub 2}O{sub 4}) has been prepared by the low-cost spray pyrolysis technique. • The optical band gap of this ternary oxide is around 1 eV and the crystallites are oriented preferentially along (111) direction. • Presenting an accurate technique “Mirage effect” for original investigation of thermal properties. • DC and AC conductivity can be both attributed to a hopping transport, while at high frequency a metallic-like behavior is observed. • A deep analysis within correlated barrier hopping (CBH) model was carried out. • Outlining a correlation between Magnetic and electrical properties.

Correlation between magnetoresistance and magnetization in Ag Mn and Au Mn spin glasses

International Nuclear Information System (INIS)

Majumdar, A.K.

1982-08-01

Magnetization has been measured between 2 and 77 K and mostly up to fields of 20 K Oe in Ag Mn (1.1 and 5.4 at %) and Au Mn (1.8 and 4.6 at %) spin glass samples where the transverse magnetoresistance was measured earlier. It is found for the first time over a wide range of temperature and magnetic field that the negative magnetoresistance varies as the square of the bulk magnetization resulting in an universal curve in the spin glass regime. A theoretical justification is provided in terms of exciting theories. (author)

St. Louis FUSRAP Lessons Learned

International Nuclear Information System (INIS)

Eberlin, J.; Williams, D.; Mueller, D.

2003-01-01

The purpose of this paper is to present lessons learned from fours years' experience conducting Remedial Investigation and Remedial Action activities at the St. Louis Downtown Site (SLDS) under the Formerly Utilized Sites Remedial Action Program (FUSRAP). Many FUSRAP sites are experiencing challenges conducting Remedial Actions within forecasted volume and budget estimates. The St. Louis FUSRAP lessons learned provide insight to options for cost effective remediation at FUSRAP sites. The lessons learned are focused on project planning (budget and schedule), investigation, design, and construction

Preparation of Mn-Zn nanoferrite by mechanical alloying

International Nuclear Information System (INIS)

Nasresfahani, M.

2007-01-01

Full text: In this research Mn-Zn nanoferrite (Mn x Zn 1-x Fe 2 O 4 ;X=0.3,0.5,0.7)were prepared by mechanical alloying of a mixture of 2 single phase ferrites, MnFe 2 O 4 and ZnFe 2 O 4 . First, ZnFe 2 O 4 and MnFe 2 O 4 were obtained by conventional ceramic technique. In this technique a mixture of related raw materials(ZnO and MnO 2 from merck company and Fe 2 O 3 domestic source) was first mixed and calcined at 1100 C for 3h in air. The starting materials used to prepare Mn-Zn nanoferrite were MnFe 2 O 4 and ZnFe 2 O 4 mixed in the ratio appropriate for the reaction: xMnFe 2 O 4+(1-x) ZnFe 2 O 4 MnxZn 1-x Fe 2 O 4 and milled at different times in SPEX8000M mixer/mill. XRD investigations was used to study the phase formation of the as-milled mixed ferrite. Using XRD patterns and Scherrer's formula, mean crystallite size of the single phase samples were calculated and were in the 10-20 nm. Saturation magnetization(Ms) of the powders was measured at room temperature by a very sensitive home made permeameter. The measured Ms values show that they are smaller than the Ms values associated with the same compound prepared by conventional ceramic technique. The decrease is due to the surface effect in nanoparticles, which can be explained on core-sell model. (authors)

Ideas and Inspirations: Good News about Diabetes Prevention and Management in Indian Country

Medline Plus

Full Text Available ... Community Members Diabetes Educator Tools Diabetes Education Lesson Plan Outlines Integrating Case Management Into Your Practice [PDF – ... Toolkit, Program Spotlights, and more! Announcing Online Lesson Plan Outlines for Educators New or seasoned educators can ...

Materials for spintronic: Room temperature ferromagnetism in Zn-Mn-O interfaces

International Nuclear Information System (INIS)

Quesada, A.; Garcia, M.A.; Crespo, P.; Hernando, A.

2006-01-01

In this paper we study the room temperature ferromagnetism reported on Mn-doped ZnO and ascribed to spin polarization of conduction electrons. We experimentally show that the ferromagnetic behaviour is associated to the coexistence of Mn 3+ and Mn +4 in MnO 2 grains where diffusion of Zn promotes the Mn 4+→ Mn 3+ reduction. Potential uses of this material in spintronic devices are analysed

A Relevant Lesson: Hitler Goes to the Mall

Science.gov (United States)

Gerwin, David

2003-01-01

A "Motivation" eliciting the "Aim" of each lesson initiates each lesson in the orthodox "developmental lesson-plan" that has dominated classroom instruction in NYC public schools for at least the past half-century. An action-research study of 38 lesson-plans (over 5 each from 5 teachers) drawn from student-teaching…

Characterizing the Hofstadter butterfly's outline with Chern numbers

International Nuclear Information System (INIS)

Goldman, N

2009-01-01

In this work, we report original properties inherent to independent particles subjected to a magnetic field by emphasizing the existence of regular structures in the energy spectrum's outline. We show that this fractal curve, the well-known Hofstadter butterfly's outline, is associated with a specific sequence of Chern numbers that correspond to the quantized transverse conductivity. Indeed the topological invariant that characterizes the fundamental energy band depicts successive stairways as the magnetic flux varies. Moreover each stairway is shown to be labelled by another Chern number which measures the charge transported under displacement of the periodic potential. We put forward the universal character of these properties by comparing the results obtained for the square and the honeycomb geometries.

Non radiative decay of Mn2+ emission in LnMB5O10:Bi,Mn (M = Mg,Cd,Zn)

International Nuclear Information System (INIS)

Jagannathan, R.; Rao, R.P.; Kutty, T.R.N.

1990-01-01

The family of lanthanide magnesium pentaborates with Tb(3+) and Eu(3+) as activators are efficient phosphor materials, Mn(2+) emission in these hosts in a subject of intensive investigation owing to its inexpensiveness. The energy transfer process from various sensitizers such as Bi(3+), Ce(3+), and Sb(3+) to Mn(2+) in these hosts have been studied in detail. The non radiative decay of Mn 2+ emission in these hosts is detailed in this paper

Preparation and electrochemical characterization of MnOOH nanowire-graphene oxide

International Nuclear Information System (INIS)

Wang Lin; Wang Dianlong

2011-01-01

Highlights: → MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C, with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. → MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. → It is found that the electrochemical resistance of MnOOH nanowire-graphene oxide composites decreases and the capacitance increases to 76 F g -1 when hydrothermal reaction is conducted in ammonia aqueous solution. → MnOOH nanowire-graphene oxide composites prepared by hydrothermal reaction in 5% ammonia aqueous solution have excellent capacitance retention ratio at scan rate from 5 mV s -1 to 40 mV s -1 . - Abstract: MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. Powder X-ray diffraction (XRD) analyses and energy dispersive X-ray analyses (EDAX) show MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. The electrochemical capacitance of MnOOH nanowire-graphene oxide composites prepared in 5% ammonia aqueous solution is 76 F g -1 at current density of 0.1 A g -1 . Moreover, electrochemical impedance spectroscopy (EIS) suggests the electrochemical resistance of MnOOH nanowire-graphene oxide composites is reduced when hydrothermal reaction is conducted in ammonia aqueous solution. The relationship between the electrochemical capacitance and the structure of MnOOH nanowire-graphene oxide composites is characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FESEM). The results indicate the electrochemical performance of MnOOH nanowire-graphene oxide composites strongly depends on their

Synthesis of MnFe2O4@Mn-Co oxide core-shell nanoparticles and their excellent performance for heavy metal removal.

Science.gov (United States)

Ma, Zichuan; Zhao, Dongyuan; Chang, Yongfang; Xing, Shengtao; Wu, Yinsu; Gao, Yuanzhe

2013-10-21

Magnetic nanomaterials that can be easily separated and recycled due to their magnetic properties have received considerable attention in the field of water treatment. However, these nanomaterials usually tend to aggregate and alter their properties. Herein, we report an economical and environmentally friendly method for the synthesis of magnetic nanoparticles with core-shell structure. MnFe2O4 nanoparticles have been successfully coated with amorphous Mn-Co oxide shells. The synthesized MnFe2O4@Mn-Co oxide nanoparticles have highly negatively charged surface in aqueous solution over a wide pH range, thus preventing their aggregation and enhancing their performance for heavy metal cation removal. The adsorption isotherms are well fitted to a Langmuir adsorption model, and the maximal adsorption capacities of Pb(II), Cu(II) and Cd(II) on MnFe2O4@Mn-Co oxide are 481.2, 386.2 and 345.5 mg g(-1), respectively. All the metal ions can be completely removed from the mixed metal ion solutions in a short time. Desorption studies confirm that the adsorbent can be effectively regenerated and reused.

Synthesis and reaction of [[HC(CMeNAr)2]Mn]2 (Ar = 2,6-iPr2C6H3): the complex containing three-coordinate manganese(I) with a Mn-Mn bond exhibiting unusual magnetic properties and electronic structure.

Science.gov (United States)

Chai, Jianfang; Zhu, Hongping; Stückl, A Claudia; Roesky, Herbert W; Magull, Jörg; Bencini, Alessandro; Caneschi, Andrea; Gatteschi, Dante

2005-06-29

This paper reports on the synthesis, X-ray structure, magnetic properties, and DFT calculations of [[HC(CMeNAr)2]Mn]2 (Ar = 2,6-iPr2C6H3) (2), the first complex with three-coordinate manganese(I). Reduction of the iodide [[HC(CMeNAr)2]Mn(mu-I)]2 (1) with Na/K in toluene afforded 2 as dark-red crystals. The molecule of 2 contains a Mn2(2+) core with a Mn-Mn bond. The magnetic investigations show a rare example of a high-spin manganese(I) complex with an antiferromagnetic interaction between the two Mn(I) centers. The DFT calculations indicate a strong s-s interaction of the two Mn(I) ions with the open shell configuration (3d54s1). This suggests that the magnetic behavior of 2 could be correctly described as the coupling between two S1 = S2 = 5/2 spin centers. The Mn-Mn bond energy is estimated at 44 kcal mol(-1) by first principle calculations with the B3LYP functional. The further oxidative reaction of 2 with KMnO4 or O2 resulted in the formation of manganese(III) oxide [[HC(CMeNAr)2]Mn(mu-O)]2 (3). Compound 3 shows an antiferromagnetic coupling between the two oxo-bridged manganese(III) centers by magnetic measurements.

Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

International Nuclear Information System (INIS)

Cao, Huawei; Lu, Pengfei; Cong, Zixiang; Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong; Gao, Tao; Wang, Shumin

2013-01-01

Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material

Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

Energy Technology Data Exchange (ETDEWEB)

Cao, Huawei [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Cong, Zixiang [School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100976 (China); Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-12-02

Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material.

As(III) oxidation by MnO2 during groundwater treatment.

Science.gov (United States)

Gude, J C J; Rietveld, L C; van Halem, D

2017-03-15

The top layer of natural rapid sand filtration was found to effectively oxidise arsenite (As(III)) in groundwater treatment. However, the oxidation pathway has not yet been identified. The aim of this study was to investigate whether naturally formed manganese oxide (MnO 2 ), present on filter grains, could abiotically be responsible for As(III) oxidation in the top of a rapid sand filter. For this purpose As(III) oxidation with two MnO 2 containing powders was investigated in aerobic water containing manganese(II) (Mn(II)), iron(II) (Fe(II)) and/or iron(III) (Fe(III)). The first MnO 2 powder was a very pure - commercially available - natural MnO 2 powder. The second originated from a filter sand coating, produced over 22 years in a rapid filter during aeration and filtration. Jar test experiments showed that both powders oxidised As(III). However, when applying the MnO 2 in aerated, raw groundwater, As(III) removal was not enhanced compared to aeration alone. It was found that the presence of Fe(II)) and Mn(II) inhibited As(III) oxidation, as Fe(II) and Mn(II) adsorption and oxidation were preferred over As(III) on the MnO 2 surface (at pH 7). Therefore it is concluded that just because MnO 2 is present in a filter bed, it does not necessarily mean that MnO 2 will be available to oxidise As(III). However, unlike Fe(II), the addition of Fe(III) did not hinder As(III) oxidation on the MnO 2 surface; resulting in subsequent effective As(V) removal by the flocculating hydrous ferric oxides. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal behaviour of Cu-Mg-Mn and Ni-Mg-Mn layered double hydroxides and characterization of formed oxides

Czech Academy of Sciences Publication Activity Database

Kovanda, F.; Grygar, Tomáš; Dorničák, V.; Rojka, T.; Bezdička, Petr; Jirátová, Květa

2005-01-01

Roč. 28, 1-4 (2005), s. 121-136 ISSN 0169-1317 Institutional research plan: CEZ:AV0Z40320502 Keywords : Cu-Mg-Mn basic carbonates * Ni-Mg-Mn hydrotalcite Subject RIV: CA - Inorganic Chemistry Impact factor: 1.324, year: 2005

System to outline the graduatestudents

Directory of Open Access Journals (Sweden)

Alberto Schanaider

Full Text Available Objective: to evaluate the system to outline the graduate students from the Post-Graduate Programs of CAPES Medicine III area. Method: it was analyzed the book of indicators and the Document of Area of the Post-Graduate Programs of Surgery, also checking the literature about this issue. Results: there was a paucity of data from most of the programs, as regards to the methods for evaluation of graduate students. The current system lacks a standard and an institutional support to outline the graduate students. In the public system there is a concentration of postgraduate students in Medicine; however, they represent a small part of those Brazilians students who finished their graduation courses in Medicine. In the current context, the quest for the post graduate courses and consequently for a research field or even a teaching career, has been replaced by the private sector jobs and the labor market, both in non-academic assistance activities. Conclusion: it is imperative to establish not only science and technology innovation policies but also educational and health policies acting harmoniously and stimulating the qualification and the teaching career, improving the post-graduate courses. It is necessary to develop a single form under the institutional guidance of CAPES with the conception of a National Program for Graduate Student in order to consolidate guidelines to mapping the graduate students of post-graduate programs in surgery, in our country.

Outline of nuclear monitor report

International Nuclear Information System (INIS)

1979-01-01

The questionnaire investigation was conducted by the Science and Technology Agency about the atomic energy monitoring. The time of report was from March 4, 1978, to March 25, 1978. The number of answers for this questionnaire was 276, and the percentage of answers is 54%. This questionnaire was sent out to men and women of various occupations and ages. There are three questions in this questionnaire; The first question is ''Do you think the measures of the government are sufficient for nuclear power plant construction[ What is the point to be improved['', the second question is ''In what points do you feel uneasiness about the safety of nuclear power generation[ What do you want to know['', and the third question is ''Have you ever seen the official report on atomic energy published by the Science and Technology Agency[ Do you think this official report on atomic energy is effective or not[ What is the point to be improved[ The abstract of each answer is outlined as the investigated result. The reports on occasions were obtained separately. The number of these reports was 162. The contents of these reports were classified into the official report on atomic energy, the safety of atomic energy, the administration of atomic energy, the developing and utilization, the monitoring system, the Mutsu, the energy saving, the reprocessing, etc., and these contents are outlined. The composition of these monitors is shown. (Nakai, Y.)

Beautiful Beads: A Lesson in Making Beads with Friendly Clay. AMACO[R] Lesson.

Science.gov (United States)

Gamble, Harriet; Gamble, David

This lesson resource includes a brief summary of the history of bead making and historic fascination with beads as adornment. A focus on design elements, color theory, craftsmanship, and technical skill in bead making is encouraged. The plan includes lesson goals and objectives; background preparation; a glossary of terms; a list of supplies; and…

XAS and XMCD investigation of Mn12 monolayers on gold.

Science.gov (United States)

Mannini, Matteo; Sainctavit, Philippe; Sessoli, Roberta; Cartier dit Moulin, Christophe; Pineider, Francesco; Arrio, Marie-Anne; Cornia, Andrea; Gatteschi, Dante

2008-01-01

The deposition of Mn(12) single molecule magnets on gold surfaces was studied for the first time using combined X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) methods at low temperature. The ability of the proposed approach to probe the electronic structure and magnetism of Mn(12) complexes without significant sample damage was successfully checked on bulk samples. Detailed information on the oxidation state and magnetic polarization of manganese ions in the adsorbates was obtained from XAS and XMCD spectra, respectively. Partial reduction of metal ions to Mn(II) was clearly observed upon deposition on Au(111) of two different Mn(12) derivatives bearing 16-acetylthio-hexadecanoate and 4-(methylthio)benzoate ligands. The average oxidation state, as well as the relative proportions of Mn(II), Mn(III) and Mn(IV) species, are strongly influenced by the deposition protocol. Furthermore, the local magnetic polarizations are significantly decreased as compared with bulk Mn(12) samples. The results highlight an utmost redox instability of Mn(12) complexes at gold surfaces, presumably accompanied by structural rearrangements, which cannot be easily revealed by standard surface analysis based on X-ray photoelectron spectroscopy and scanning tunnelling microscopy.

Influence of Mn incorporation for Ni on the magnetocaloric properties of rapidly solidified off-stoichiometric NiMnGa ribbons

Energy Technology Data Exchange (ETDEWEB)

Dey, Sushmita; Singh, Satnam; Roy, R.K.; Ghosh, M.; Mitra, A.; Panda, A.K., E-mail: akpanda@nmlindia.org

2016-01-01

The present investigation addresses the magnetocaloric behaviour in a series of Ni{sub 77−x}Mn{sub x}Ga{sub 23} (x=23, 24, 25, 27 and 29) rapidly solidified alloys prepared in the form of ribbons by melt spinning technique. The approach of the study is to identify the off-stoichiometric composition wherein room temperature magneto-structural transformation is achieved. The alloy chemistry was tailored through Mn incorporation for Ni such that the magnetic and structural transitions were at close proximity to achieve highest entropy value of ΔS equal to 8.51 J Kg{sup −1} K{sup −1} for #Mn{sub 24} ribbon measured at an applied field of 3 T. When such transitions are more staggered as in #Mn{sub 29} the entropy value of ribbon reduced to as low as 1.61 J Kg{sup −1} K{sup −1}. Near room temperature transformations in #Mn{sub 24} ribbon have been observed through calorimetric and thermomagnetic evaluation. Reverse martensitic transformation (martensite→autstenite) temperature indicates not only distinct change in the saturation flux density but also an inter-martensitic phase. Microstructural analysis of #Mn{sub 24} alloy ribbon revealed structural ordering with the existence of plate morphology evidenced for martensitic phase. - Highlights: • Magnetocaloric effect in a series of melt spun NiMnGa ribbon is addressed. • The alloy series revealed austenitic state as well as its presence with martensite. • The morphology of the ribbons has been shown and discussed through phase analysis. • Influence of magnetising field on entropy and relative cooling power is discussed. • Influence of intermartensitic state on magnetization plots have also been shown.

What is the Valence of Mn in Ga(1-x)Mn(x)N?

Science.gov (United States)

Nelson, Ryky; Berlijn, Tom; Moreno, Juana; Jarrell, Mark; Ku, Wei

2015-11-06

We investigate the current debate on the Mn valence in Ga(1-x)Mn(x)N, a diluted magnetic semiconductor (DMS) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to 2+ (d(5)), but in a mixed spin configuration with average magnetic moments of 4μ(B). By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: (1) an effective d(4) picture ideal for local physics, and (2) an effective d(5) picture suitable for extended properties. In the latter, our results further reveal a few novel physical effects, and pave the way for future realistic studies of magnetism. Our study not only resolves one of the outstanding key controversies of the field, but also exemplifies the general need for multiple effective descriptions to account for the rich low-energy physics in many-body systems in general.

First-principles spin-transfer torque in CuMnAs |GaP |CuMnAs junctions

Science.gov (United States)

Stamenova, Maria; Mohebbi, Razie; Seyed-Yazdi, Jamileh; Rungger, Ivan; Sanvito, Stefano

2017-02-01

We demonstrate that an all-antiferromagnetic tunnel junction with current perpendicular to the plane geometry can be used as an efficient spintronic device with potential high-frequency operation. By using state-of-the-art density functional theory combined with quantum transport, we show that the Néel vector of the electrodes can be manipulated by spin-transfer torque. This is staggered over the two different magnetic sublattices and can generate dynamics and switching. At the same time the different magnetization states of the junction can be read by standard tunneling magnetoresistance. Calculations are performed for CuMnAs |GaP |CuMnAs junctions with different surface terminations between the antiferromagnetic CuMnAs electrodes and the insulating GaP spacer. We find that the torque remains staggered regardless of the termination, while the magnetoresistance depends on the microscopic details of the interface.

Facile solvothermal synthesis of graphene-MnOOH nanocomposites

International Nuclear Information System (INIS)

Chen Sheng; Zhu Junwu; Huang Huajie; Zeng Guiyu; Nie Fude; Wang Xin

2010-01-01

In this paper, we report a facile solvothermal route capable of aligning MnOOH nanocrystals on graphene. X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations indicate that the exfoliated graphene sheets are decorated randomly by MnOOH nanocrystals, forming well-dispersed graphene-MnOOH nanocomposites. Dissolution-crystallization and oriented attachment are speculated to be the vital mechanisms in the synthetic process. The attachment of additives, such as MnOOH nanoparticles, are found to be beneficial for the exfoliation of GO as well as preventing the restack of graphene sheets. Moreover, cyclic voltammetry (CV) analyses suggest that the electrochemical reversibility is improved by anchoring MnOOH on graphene. Notably, the as-fabricated nanocomposites reveal unusual catalytic performance for the thermal decomposition of ammonium perchlorate (AP) due to the concerted effects of graphene and MnOOH. This template-free method is easy to reproduce, and the process proceeds at a low temperature and can be readily extended to prepare other graphene-based nanocomposites. - Graphical abstract: Manganese oxyhydroxide nanocrystals have been successfully attached onto the graphene sheets via an oriented attachment and dissolution-crystallization process, forming a nanocomposite with unusual catalytic capabilities. Display Omitted

Electronic and magnetic properties of MnAu nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Safi 46000 (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O; El moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

2014-03-15

Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the MnAu nanoparticles. Polarized spin is included in calculations within the framework of the antiferromagnetic. The Mn magnetic moments where considered to be along c axes. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest-neighbour Heisenberg and XY models on a MnAu nanoparticles is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different nanoparticles. The exchanges interactions between the magnetic atoms are obtained for MnAu nanoparticles. - Highlights: • The electronic properties of the MnAu nanoparticles are studied using the DFT and FLAPW. • Magnetic moment is computed. • The ab initio calculations are used as input for HTSEs to compute other magnetic parameters. • The exchanges interactions and blocking temperature are obtained for MnAu nanoparticles.

Electronic and magnetic properties of MnAu nanoparticles

International Nuclear Information System (INIS)

Masrour, R.; Hlil, E.K.; Hamedoun, M.; Benyoussef, A.; Mounkachi, O; El moussaoui, H.

2014-01-01

Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the MnAu nanoparticles. Polarized spin is included in calculations within the framework of the antiferromagnetic. The Mn magnetic moments where considered to be along c axes. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest-neighbour Heisenberg and XY models on a MnAu nanoparticles is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different nanoparticles. The exchanges interactions between the magnetic atoms are obtained for MnAu nanoparticles. - Highlights: • The electronic properties of the MnAu nanoparticles are studied using the DFT and FLAPW. • Magnetic moment is computed. • The ab initio calculations are used as input for HTSEs to compute other magnetic parameters. • The exchanges interactions and blocking temperature are obtained for MnAu nanoparticles

Electronic and magnetic structures of ferrimagnetic Mn{sub 2}Sb compound

Energy Technology Data Exchange (ETDEWEB)

Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, 63 46000 Safi (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O.; El moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

2015-01-15

The Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the Mn{sub 2}Sb compound. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn{sub 1} and Mn{sub 2} atoms. Magnetic moment considered to lie along (0 0 1) axes are computed. The antiferromagnetic energy of Mn{sub 2}Sb systems is obtained. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The exchange interactions between the magnetic atoms Mn{sub 1}−Mn{sub 2} in Mn{sub 2}Sb are given by using the mean field theory. The HTSEs of the magnetic susceptibility of with the magnetic moments in Mn{sub 2}Sb (m{sub Mn{sub 1}}and m{sub Mn{sub 2}}) through Ising model is given up to tenth order series in (x=J(Mn{sub 1}−Mn{sub 2})/k{sub B}T). The Néel temperature T{sub N}(K) is obtained by HTSEs applied to the magnetic susceptibility series combined with the Padé approximant method. The critical exponent γ associated with the magnetic susceptibility is deduced as well. - Highlights: • Ab initio calculations is using to investigate both electronic and magnetic properties of the Mn{sub 2}Sb compound. • Obtained data from ab initio calculations are used as input for the HTSEs. • The Néel temperature is obtained for Mn{sub 2}Sb compound.

Experimental and first-principles study of ferromagnetism in Mn-doped zinc stannate nanowires

KAUST Repository

Deng, Rui; Zhou, Hang; Li, Yong-Feng; Wu, Tao; Yao, Bin; Qin, Jie-Ming; Wan, Yu-Chun; Jiang, Da-Yong; Liang, Qing-Cheng; Liu, Lei

2013-01-01

Room temperature ferromagnetism was observed in Mn-doped zinc stannate (ZTO:Mn) nanowires, which were prepared by chemical vapor transport. Structural and magnetic properties and Mn chemical states of ZTO:Mn nanowires were investigated by X-ray diffraction, superconducting quantum interference device (SQUID) magnetometry and X-ray photoelectron spectroscopy. Manganese predominantly existed as Mn2+ and substituted for Zn (Mn Zn) in ZTO:Mn. This conclusion was supported by first-principles calculations. MnZn in ZTO:Mn had a lower formation energy than that of Mn substituted for Sn (MnSn). The nearest neighbor MnZn in ZTO stabilized ferromagnetic coupling. This observation supported the experimental results. © 2013 AIP Publishing LLC.

Experimental and first-principles study of ferromagnetism in Mn-doped zinc stannate nanowires

KAUST Repository

Deng, Rui

2013-07-17

Room temperature ferromagnetism was observed in Mn-doped zinc stannate (ZTO:Mn) nanowires, which were prepared by chemical vapor transport. Structural and magnetic properties and Mn chemical states of ZTO:Mn nanowires were investigated by X-ray diffraction, superconducting quantum interference device (SQUID) magnetometry and X-ray photoelectron spectroscopy. Manganese predominantly existed as Mn2+ and substituted for Zn (Mn Zn) in ZTO:Mn. This conclusion was supported by first-principles calculations. MnZn in ZTO:Mn had a lower formation energy than that of Mn substituted for Sn (MnSn). The nearest neighbor MnZn in ZTO stabilized ferromagnetic coupling. This observation supported the experimental results. © 2013 AIP Publishing LLC.

Stability and electronic properties of Cd0.75Mn0.25S and Cd0.75Mn0.25Se in B3 phase

Energy Technology Data Exchange (ETDEWEB)

Rani, Anita [Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab (India); Kumar, Ranjan [Panjab University, Department of Physics, Chandigarh (India)

2015-08-15

We studied the structural, elastic, spin-polarized electronic band structures and magnetic properties of the diluted magnetic semiconductor Cd{sub 1-x}Mn{sub x}S and Cd{sub 1-x} Mn{sub x}Se in zinc blende phase (B3) for x = 0.25 using ab initio method. The calculations were performed by using density functional theory as implemented in the Spanish Initiative for Electronic Simulations with Thousands of Atoms code using local density approximation. Calculated electronic band structures and magnetic properties of Cd{sub 1-x}Mn{sub x}S are discussed in terms of contribution of Mn 3d{sup 5} 4s{sup 2}, Cd 4d{sup 10} 5s{sup 2}, S 3s{sup 2} 3p{sup 4} orbitals. The total magnetic moment is found to be 5.00 μ{sub b} for Cd{sub 1-x}Mn{sub x}S and Cd{sub 1-x}Mn{sub x}Se at x = 0.25. This value indicates that Mn atom adds no hole carrier to the perfect CdS crystal. We determine the spin-exchange splitting energies produced by Mn 3d states, s-d exchange constant N{sub 0}α, and p-d exchange constant N{sub 0}β. We found that Mn-doped systems are ferromagnetic. Calculated results are in good agreement with previous studies. (orig.)

α-MnO2 nanowires transformed from precursor δ-MnO2 by refluxing under ambient pressure: The key role of pH and growth mechanism

International Nuclear Information System (INIS)

Zhang Qin; Xiao Zhidong; Feng Xionghan; Tan Wenfeng; Qiu Guohong; Liu Fan

2011-01-01

α-MnO 2 nanowires were obtained by reflux treatment of precursor δ-MnO 2 in acidic medium under ambient pressure. The great effects of pH on the transformation of δ-MnO 2 to α-MnO 2 and the concentration of coexistent cations (K + , Mn 2+ ) was investigated in systematically designed experiments by using powder X-ray diffraction and atomic absorption spectrometry analysis. The specific surface area of the products could be simply controlled by adjusting the initial pH value of the suspension. The micro-morphologies during the transition process from the precursors to final products were characterized by SEM and TEM. A dissolution-recrystallization mechanism was proposed to describe the growth process of the one-dimensional nanowire. MnO x units or MnO 6 octahedra was formed firstly from the dissolution of outmost surfaces of δ-MnO 2 , followed by a rearrangement/crystallization to form one-dimensional α-MnO 2 nanowire. In addition, the time-dependent process of dissolution would take place gradually from the external to internal of the precursor.

Electrochemical Properties of Hydrogen-Storage Alloys ZrMn{sub 2}Ni{sub x} and ZrMnNi{sub 1+x} for Ni-MH Secondary Battery

Energy Technology Data Exchange (ETDEWEB)

Park, Hye Ryoung [Faculty of Applied Chemistry, Chonnam National University, Kwangju (Korea); Kwon, Ik Hyun [Automobile High-Technology Research Institute, Division of Advanced Materials Engineering, Chonbuk National University, Chonju (Korea)

2001-04-01

In order to improve the performance of AB{sub 2}-type hydrogen-storage alloys for Ni-MH secondary battery, AB{sub 2}-type alloys, ZrMn{sub 2}Ni{sub x}(x=0.0, 0.3, 0.6, 0.9 and 1.2) and ZrMnNi{sub 1+x}(x=0.0, 0.1, 0.2, 0.3 and 0.4) were prepared as the Zr-Mn-Ni three component alloys. The hydrogen-storage and the electrochemical properties were investigated. The C14 Laves phase formed in all alloys of ZrMn{sub 2}Ni{sub x}(x=0.0 {approx} 1.2). The equilibrium plateau pressure of the alloy, ZrMn{sub 2}Ni{sub 0.6}-H{sub 2} system, was about 0.5 atm at 30 degree C. Among these alloys, ZrMn{sub 2}Ni{sub 0.6} was the easiest to activate, and it had the largest discharge capacity as well as the best cycling performance. The C14 Laves phase also formed in all alloys of ZrMnNi{sub 1+x}(x=0.0 {approx} 0.4). The equilibrium plateau pressure of the alloy, ZrMnNi{sub 1.0}-H{sub 2} system, was about 0.45 atm at 30 degree C. Among these alloys, ZrMnNi{sub 1.0} was the easiest to activate, taking only 3 charge-discharge cycles, and it had the largest discharge capacity of 42 mAh/g. Among these alloys, ZrMn{sub 2}Ni{sub x}(x=0.0 {approx} 1.2) and ZrMnNi{sub 1+x}(x=0.0 {approx} 0.4), ZrMnNi{sub 1.0} had the largest discharge capacity (maximum value of 42 mAh/g), and it showed the fastest activation and good cycling performance. 23 refs., 4 figs., 2 tabs.

Properties of Mn-doped ZnO nanopowder

Energy Technology Data Exchange (ETDEWEB)

Schlenker, E.; Bakin, A.; Wehmann, H.H.; Al-Suleiman, M.; Waag, A. [Technical University Braunschweig, Institute of Semiconductor Technology, Braunschweig (Germany); Schmid, H.; Mader, W. [Universitaet Bonn, Institut fuer Anorganische Chemie, Bonn (Germany); Bremers, H.; Hangleiter, A. [Technical University Braunschweig, Institute of Applied Physics, Braunschweig (Germany); Luedke, J.; Albrecht, M. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany)

2008-06-15

The structural and magnetic properties of Mn-doped ZnO nanopowder are investigated and compared to undoped ZnO crystals. Mn incorporation leads to an increase in the lattice constants as revealed by X-ray diffraction measurements. An inhomogeneous distribution of the Mn atoms within the nanopowder was detected by energy-dispersive X-ray and electron-energy-loss spectroscopy measurements. Magnetic features are investigated by means of SQUID magnetometry on ensembles of powder particles as well as by magnetic force microscopy to study the behavior of single grains. (orig.)

Improvement of the photocatalytic activity of magnetite by Mn-incorporation

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Hudson W.P., E-mail: hudsonwpc@yahoo.com.br; Hammer, Peter, E-mail: peter@iq.unesp.br; Pulcinelli, Sandra H., E-mail: sandrap@iq.unesp.br; Santilli, Celso V., E-mail: santilli@iq.unesp.br; Molina, Eduardo F., E-mail: efmolina@iq.unesp.br

2014-02-15

Highlights: • Efficiently methylene blue dye discoloration using an Mn doped magnetite catalyst. • Evidence for isomorphic substitution of Fe{sup 2+} by Mn{sup 2+} in the octahedral structure. • Mechanism of the enhanced photocatalysis induced by active Mn sites. • Importance of the Mn reaction rate constant and effective surface area. -- Abstract: Mn-incorporated Fe{sub 3}O{sub 4} photocatalysts were prepared by a simple co-precipitation method. Photocatalytic discoloration of Methylene Blue (MB) was used to evaluate the performance of these catalysts. The DSC results have shown that the insertion of Mn into Fe{sub 3}O{sub 4} lattice has increased converting Fe{sub 3}O{sub 4} to γ-Fe{sub 2}O{sub 3}. This is accompanied by a decrease of surface area and of crystallinity, as detected by XRD. The analysis of the chemical environment by XPS has shown that Mn{sup 2+} replaces Fe{sup 2+} preferentially in the octahedral sites while Mn{sup 3+} replaces Fe{sup 3+} of inverse spinel sites. The Mn-incorporated samples were significantly more efficient in MB discoloration assisted by UVA irradiation and H{sub 2}O{sub 2}. It was also found that ascorbic acid prevents H{sub 2}O{sub 2} decomposition, by scavenging preferentially ·OOH radicals produced at Mn sites. Finally, the results reported here can contribute for a better comprehension of the activity of composite catalysts and the design of efficient systems for discoloration of organic pollutants.

Practical experiences of, and lessons learnt from, Internet technologies in higher education

Directory of Open Access Journals (Sweden)

Simon Polovina

1999-01-01

Full Text Available The paper addresses how the Internet as computer-mediated communication is affecting teaching and learning in higher education institutions, particularly as these institutions face increasing competition due to the emergence of Web-based collaboration and assessment technologies. London’s South Bank University (SBU, a typical modern-day higher education institution is thereby in the process of integrating Internet technologies into its conventional and distance learning programmes. From its practical experiences so far SBU has learnt a variety of valuable lessons. In particular the technical and social aspects that determine the choice and use of the most appropriate software tools were identified, as well as a new approach towards online (Internet / Web subject reference sources was outlined. From SBU’s anecdotal experiences, useful recommendations are made for the effective use of Internet technologies that applies to many higher educational institutions.

Analysing the Integration of Engineering in Science Lessons with the Engineering-Infused Lesson Rubric

Science.gov (United States)

Peterman, Karen; Daugherty, Jenny L.; Custer, Rodney L.; Ross, Julia M.

2017-01-01

Science teachers are being called on to incorporate engineering practices into their classrooms. This study explores whether the Engineering-Infused Lesson Rubric, a new rubric designed to target best practices in engineering education, could be used to evaluate the extent to which engineering is infused into online science lessons. Eighty lessons…

Magnetic anisotropies of (Ga,Mn)As films and nanostructures

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, Frank

2011-02-02

In this work the magnetic anisotropies of the diluted magnetic semiconductor (Ga,Mn)As were investigated experimentally. (Ga,Mn)As films show a superposition of various magnetic anisotropies which depend sensitively on various parameters such as temperature, carrier concentration or lattice strain. However, the anisotropies of lithographically prepared (Ga,Mn)As elements differ significantly from an unpatterned (Ga,Mn)As film. In stripe-shaped structures this behaviour is caused by anisotropic relaxation of the compressive lattice strain. In order to determine the magnetic anisotropies of individual (Ga,Mn)As nanostructures a combination of ferromagnetic resonance and time-resolved scanning Kerr microscopy was employed in this thesis. In addition, local changes of the magnetic anisotropy in circular and rectangular structures were visualized by making use of spatially resolved measurements. Finally, also the influence of the laterally inhomogeneous magnetic anisotropies on the static magnetic properties, such as coercive fields, was investigated employing spatially resolved static MOKE measurements on individual (Ga,Mn)As elements. (orig.)

Oxidative and antibacterial activity of Mn3O4

International Nuclear Information System (INIS)

Chowdhury, Al-Nakib; Azam, Md. Shafiul; Aktaruzzaman, Md.; Rahim, Abdur

2009-01-01

Mn 3 O 4 nanoparticles with diameter ca. 10 nm were synthesized by the forced hydrolysis of Mn(II) acetate at 80 deg. C. The X-ray diffraction (XRD), Fourier transform infra red (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques were employed to study structural features and chemical composition of the nanoparticles. The unique oxidative activity of the Mn 3 O 4 nanoparticles was demonstrated in the polymerization and dye degradation reactions. On adding Mn 3 O 4 suspension to an acidic solution of aniline, yielded immediately green sediment of polyaniline (PANI). The organic dyes, viz., methylene blue (MB) and procion red (PR) were found to be completely decolorized from their aqueous solution on treating the dyes with Mn 3 O 4 suspension in acidic media. The Mn 3 O 4 nanoparticles also showed a clear antibacterial activity against the Vibrio cholerae, Shigella sp., Salmonella sp., and Escherichi coli bacteria that cause cholera, dysentery, typhoid, and diarrhea diseases, respectively.

An African Perspective on Peace Education: Ubuntu Lessons in Reconciliation

Science.gov (United States)

Murithi, Tim

2009-05-01

This essay examines the value of educating for peace. It does this through a consideration of the African cultural world-view known as ubuntu, which highlights the essential unity of humanity and emphasises the importance of constantly referring to the principles of empathy, sharing and cooperation in efforts to resolve our common problems. The essay is not based on field research, but rather on a discussion of the issues pertaining to ubuntu and peace education. The discussion focuses on how Desmond Tutu utilised the principles of ubuntu during his leadership of the South African Truth and Reconciliation Commission. It also outlines the five stages of the peacemaking process found among ubuntu societies: acknowledging guilt; showing remorse and repenting; asking for and giving forgiveness; and paying compensation or reparations as a prelude to reconciliation. Potential lessons for educating for peace and reconciliation are highlighted based on the premise that the ubuntu approach to human relationship-building can offer an example to the world.

Alvin (Al) Sieff: Thoughts About and Lessons from a Great Engineer

Science.gov (United States)

Tauber, Michael

2010-01-01

Alvin (Al) Seiff was known as a world-class atmospheric scientist during the last three decades of his life. Equally deserving, however, were his prior achievements as an innovative engineer, an exceptional technical manager, and a mentor of young engineers at NASA Ames Research Center. This paper outlines Al's role in developing Ames ballistic range facilities, probably the most advanced in the world at that time, and his seminal 1963 report that contained the concepts used to reconstruct the atmospheres of Mars, Venus, Jupiter and Titan. Also discussed is my affiliation with Al after he hired me in 1962, including our joint work on Mars missions and investigating the feasibility that a Jupiter probe could survive entry, work that eventually led to the development of the Galileo probe. Finally, suggestions are offered for speeding the analysis and design of thermal protection systems based on lessons learned from successful probes and landers.

Single Crystal Growth of Multiferroic Double Perovskites: Yb2CoMnO6 and Lu2CoMnO6

Directory of Open Access Journals (Sweden)

Hwan Young Choi

2017-02-01

Full Text Available We report on the growth of multiferroic Yb2CoMnO6 and Lu2CoMnO6 single crystals which were synthesized by the flux method with Bi2O3. Yb2CoMnO6 and Lu2CoMnO6 crystallize in a double-perovskite structure with a monoclinic P21/n space group. Bulk magnetization measurements of both specimens revealed strong magnetic anisotropy and metamagnetic transitions. We observed a dielectric anomaly perpendicular to the c axis. The strongly coupled magnetic and dielectric states resulted in the variation of both the dielectric constant and the magnetization by applying magnetic fields, offering an efficient approach to accomplish intrinsically coupled functionality in multiferroics.

Lessons Learned: Transfer of the High-Definition Circulating Tumor Cell Assay Platform to Development as a Commercialized Clinical Assay Platform.

Science.gov (United States)

Kuhn, P; Keating, S M; Baxter, G T; Thomas, K; Kolatkar, A; Sigman, C C

2017-11-01

Planning and transfer of a new technology platform developed in an academic setting to a start-up company for medical diagnostic product development may appear daunting and costly in terms of complexity, time, and resources. In this review we outline the key steps taken and lessons learned when a technology platform developed in an academic setting was transferred to a start-up company for medical diagnostic product development in the interest of elucidating development toolkits for academic groups and small start-up companies starting on the path to commercialization and regulatory approval. © 2017, The American Society for Clinical Pharmacology and Therapeutics.

Local Structure and Magnetism of (Ga,Mn)As

CERN Document Server

AUTHOR|(CDS)2093111; Temst, Kristiaan

Throughout the years, dilute magnetic semiconductors (DMS) have emerged as promising materials for semiconductor-based spintronics. In particular, (Ga,Mn)As has become the model system in which to explore the physics of carrier-mediated ferromagnetism in semiconductors and the associated spintronic phenomena, with a number of interesting functionalities and demonstrated proof-of-concept devices. It constitutes the perfect example of how the magnetic behavior of DMS materials is strongly influenced by local structure. In this thesis, we address key aspects of the interplay between local structure and ferromagnetism of (Ga,Mn)As. We unambiguously identify the lattice site occupied by interstitial Mn as the tetrahedral interstitial site with As nearest neighbors T(As). We show, furthermore, that the T(As) is the most energetically favorable site regardless of the interstitial atom forming or not complexes with substitutional Mn. We also evaluate the thermal stability of both interstitial and substitutional Mn si...

Lithium intercalation into layered LiMnO2

DEFF Research Database (Denmark)

Vitins, G.; West, Keld

1997-01-01

Recently Armstrong and Bruce(1) reported a layered modification of lithium manganese oxide, LiMnO2, isostructural with LiCoO2. LiMnO2 obtained by ion exchange from alpha-NaMnO2 synthesized in air is characterized by x-ray diffraction and by electrochemical insertion and extraction of lithium...... in a series of voltage ranges between 1.5 and 4.5 V relative to a lithium electrode. During cycling voltage plateaus at 3.0 and 4.0 V vs. Li develop, indicating that the material is converted from its original layered structure to a spinel structure. This finding is confirmed by x-ray diffraction. Contrary...... to expectations based on thermodynamics, insertion of larger amounts of lithium leads to a more complete conversion. We suggest that a relatively high mobility of manganese leaves Li and Mn randomly distributed in the close-packed oxygen lattice after a deep discharge. This isotropic Mn distribution can...

Raising the temperature of the UK heat pump market: Learning lessons from Finland

International Nuclear Information System (INIS)

Hannon, Matthew J.

2015-01-01

Heat pumps play a central role in decarbonising the UK's buildings sector as part of the Committee on Climate Change's (CCC) updated abatement scenario for meeting the UK's fourth carbon budget. However, the UK has one of the least developed heat pump markets in Europe and renewable heat output from heat pumps will need to increase by a factor of 50 over the next 15 years to be in line with the scenario. Therefore, this paper explores what lessons the UK might learn from Finland to achieve this aim considering that its current level of heat pump penetration is comparable with that outlined in the CCC scenario for 2030. Despite the two countries’ characteristic differences we argue they share sufficient similarities for the UK to usefully draw some policy-based lessons from Finland including: stimulating new-build construction and renovation of existing stock; incorporating renewable heat solutions in building energy performance standards; and bringing the cost of heat pumps in-line with gas fired heating via a combination of subsidies, taxes and energy RD&D. Finally, preliminary efforts to grow the heat pump market could usefully focus on properties unconnected to the gas-grid, considering these are typically heated by relatively expensive oil or electric heating technologies. -- Highlights: •Heat pumps are expected to play a key role in meeting the UK's 4th carbon budget. •Today, heat pump deployment per capita in the UK is one of the lowest in Europe. •Finland offers some policy lessons given its high level of heat pump deployment. •Policies: raising build rates, building standards and heat pump cost-effectiveness. •Deployment efforts should focus on buildings not heated by relatively low-cost gas

Magnetism of DyMn2 and HoMn2 - 57Fe and 119Sn Moessbauer studies

International Nuclear Information System (INIS)

Krop, K.; Haeufler, T.; Hilscher, G.; Steiner, W.

1995-01-01

Moessbauer spectra were measured for two Laves phase compounds DyMn 2 and HoMn 2 in which manganese was substituted to 0.5% with 57 Fe and to 0.2% with 119 Sn. At 4.2 K the 57 Fe and 119 Sn spectra of the Dy compound were unambiguously fitted each with two Zeeman patterns (with relative contributions to the spectra 3:1) corresponding to two different Mn sites - magnetic and nonmagnetic. Transferred hyperfine fields at 119 Sn were found to be proportional to the magnetic moment of Dy and its ferromagnetic component, corroborating the magnetic structure found in neutron diffraction (ND) experiment. The same procedure was carried on with the spectra measured for the Ho compound, but the above mentioned proportionality was not found. ((orig.))

Youth Unemployment Outline of a Psychosocial Perspective

Science.gov (United States)

Stamm, Margrit

2006-01-01

This analysis of education policy constitutes an attempt to outline the problem of youth unemployment. Building on a recognition that structural change in the "society of labourers" has also affected the social entity "young people", it shows the problems inherent in our concept of linear transitions to working life and the…

Multi-scale Gaussian representation and outline-learning based cell image segmentation

Science.gov (United States)

2013-01-01

Background High-throughput genome-wide screening to study gene-specific functions, e.g. for drug discovery, demands fast automated image analysis methods to assist in unraveling the full potential of such studies. Image segmentation is typically at the forefront of such analysis as the performance of the subsequent steps, for example, cell classification, cell tracking etc., often relies on the results of segmentation. Methods We present a cell cytoplasm segmentation framework which first separates cell cytoplasm from image background using novel approach of image enhancement and coefficient of variation of multi-scale Gaussian scale-space representation. A novel outline-learning based classification method is developed using regularized logistic regression with embedded feature selection which classifies image pixels as outline/non-outline to give cytoplasm outlines. Refinement of the detected outlines to separate cells from each other is performed in a post-processing step where the nuclei segmentation is used as contextual information. Results and conclusions We evaluate the proposed segmentation methodology using two challenging test cases, presenting images with completely different characteristics, with cells of varying size, shape, texture and degrees of overlap. The feature selection and classification framework for outline detection produces very simple sparse models which use only a small subset of the large, generic feature set, that is, only 7 and 5 features for the two cases. Quantitative comparison of the results for the two test cases against state-of-the-art methods show that our methodology outperforms them with an increase of 4-9% in segmentation accuracy with maximum accuracy of 93%. Finally, the results obtained for diverse datasets demonstrate that our framework not only produces accurate segmentation but also generalizes well to different segmentation tasks. PMID:24267488

MnDOT Library strategic plan : final report.

Science.gov (United States)

2017-06-01

MnDOTs Senior Leadership asked MnDOT Library to develop a Strategic Plan that identifies and reviews the challenges facing the Library over the next five years to better address the evolving needs of the department and users. The strategic plan is...

MnS spheres: Shape-controlled synthesis and its magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Qi, Kezhen [Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang, 110034 (China); Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin, 300071 (China); State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 (China); Wang, Yan-Qin, E-mail: wangyanqin@tyut.edu.cn [Shanxi Key Lab. of Material Strength & Structural Impact, College of Mechanics, Taiyuan University of Technology, Taiyuan, 030024 (China); Rengaraj, Selvaraj, E-mail: srengaraj1971@yahoo.com [Department of Chemistry, College of Science, Sultan Qaboos University, Muscat, 123 (Oman); Al Wahaibi, Bushra [Department of Chemistry, College of Science, Sultan Qaboos University, Muscat, 123 (Oman); Mohamed Jahangir, A.R. [Biyaq Oil Field Services LLC, Mina Al Fahal, Muscat, 123 (Oman)

2017-06-01

Sphere-like MnS hierarchical microstructures were successfully synthesized by a simple hydrothermal approach, which are composed of the size tunable and self-assembled nanoparticles. These hierarchical microspheres are γ-MnS phase, which is confirmed by X-ray diffraction (XRD) results, and the stoichiometry of MnS microspheres is checked by XPS measurement. Morphological studies performed by scanning electron microscopy (SEM) method show that the as-prepared γ-MnS samples are hierarchical microspheres. The size and morphology of composed nanoparticles can be turned by the concentration of L-Cystein molecules. Here, L-Cystein not only plays a role of sulfur source but also capping agent. Furthermore, a rational mechanism about the formation and evolution of the products is proposed. The present work shows that the origin of the observed difference of magnetic properties is due to the morphology difference of MnS crystals. - Highlights: • Sphere-like MnS hierarchical microstructures were synthesized and characterized. • The size and morphology of MnS crystals can be turned by the concentration of L-Cystein molecules. • The morphology of MnS hierarchitectures exerts a remarkable effect on their magnetic property.

Neutron scattering study of MnX2 (X = Br, I)

International Nuclear Information System (INIS)

Sato, Taku; Kadowaki, Hiroaki.

1993-01-01

Successive magnetic phase transitions in MnX 2 (X = Br, I), found by bulk measurements, are studied by neutron scattering experiments. There occur two (T N1 = 2.32K, T N2 = 2.17K) and three (T N1 = 3.95K, T N2 = 3.8K, T N3 = 3.45K) phase transitions in MnBr 2 and MnI 2 , respectively. We have found that magnetic structures of the both compounds in the intermediate temperature phases (MnBr 2 : T N1 > T > T N2 ; MnI 2 : T N1 > T > T N3 ) are transverse sinusoidally-modulated structures with incommensurate wave-vectors which vary as a function of temperature. As the temperature is lowered into the lowest temperature phases, the magnetic structures change via first order transition into ↑↑↓↓ and a helical structure for MnBr 2 and MnI 2 , respectively, which were determined by previous experiments. The successive phase transitions in MnBr 2 are accounted for quantitatively using a mean field approximation of a Hamiltonian consisting of exchange interactions up to third inter- and third intra-layer neighbor sites and the dipolar interaction. (author)

Magnetic properties of Mn-doped ZnO diluted magnetic semiconductors

International Nuclear Information System (INIS)

Liu Xuechao; Zhang Huawei; Zhang Tao; Chen Boyuan; Chen Zhizhan; Song Lixin; Shi Erwei

2008-01-01

A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn 2+ for Zn 2+ without additional acceptor doping. The substitution of N for O (N O −) is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn 2+ and Mn 3+ via N O − . The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration

Determination of hydrogen solubility in Fe-Mn-C melts

Energy Technology Data Exchange (ETDEWEB)

Lob, Alexander; Senk, Dieter [Institute of Ferrous Metallurgy (IEHK), RWTH Aachen University (Germany); Hallstedt, Bengt [Materials Chemistry (MCh), RWTH Aachen University (Germany)

2011-02-15

High manganese steels are supposed to be sensitive to hydrogen embrittlement. This can be explained by increased hydrogen solubility in comparison to unalloyed steels. To minimise hydrogen pick up during melting operations, it is necessary to know accurately the hydrogen solubility as function of hydrogen partial pressure, temperature and Mn content. In this work in situ measurements of hydrogen content at 12, 18 and 23 wt.% Mn (and 0.6 wt.% C) using the Hydris {sup registered} system are compared to pin-tube measurements. Below about 7 ppm [H] both methods gave the same results and above 7 ppm [H] the in situ measurement showed slightly higher hydrogen contents because some hydrogen is lost during quenching with the pin-tube method. The measured solubilities were compared with thermodynamic calculations. Using dilute solution theory with data developed for alloyed Fe-based melts with up to 10 wt.% Mn gives reasonable results except that the hydrogen solubility is slightly underestimated for the presently investigated Mn contents. This could be compensated by using an interaction parameter of e{sup Mn}{sub H}=-0.004 instead of e{sup Mn}{sub H}=-0.0012. A Calphad type extrapolation from the binary Fe-H, Mn-H and Fe-Mn systems gave results very close to the experimental ones. This work is a contribution from the collaborative research centre SFB 761 ''Steel - ab initio''. (Copyright copyright 2011 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Moessbauer spectroscopy of Fe-Mn-Cu alloys

International Nuclear Information System (INIS)

Paduani, Clederson; Krause, Joao Carlos; Yoschida, M.I. Soares

2004-01-01

Full text: Although a continuous series of solid solutions exists between Cu and Mn, Fe and Cu are miscible only a few percent at higher temperatures. In moderately concentrated Cu-Mn alloys the Mn moments are bound to the long ranged antiferromagnetic order and the perpendicular components form an X-Y spin glass. Copper alloys are largely employed in various industrial applications. In this work we study the magnetic properties of iron-rich disordered Fe-Mn-Cu alloys with the bcc structure with the experimental techniques of X-ray diffraction (XRD), Moessbauer spectroscopy (MS) and thermogravimetry (TGA). We investigate the formation of a solid solution with the bcc structure as well as the effect of the composition on the structural and magnetic properties of these alloys. A Rietveld analysis of the XRD diffractograms indicate that all prepared samples are single phase and are well crystallized with a bcc structure. (author)

Synthesis and characterization of single-phase Mn-doped ZnO

Science.gov (United States)

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.

Synthesis and characterization of single-phase Mn-doped ZnO

International Nuclear Information System (INIS)

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

2009-01-01

Different samples of Zn 1-x Mn x O 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 2 O 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 (τ 1 ) at defect site (τ 2 ) and average (τ av ) increases with milling time.

Phase relations and gibbs energies in the system Mn-Rh-O

Science.gov (United States)

Jacob, K. T.; Sriram, M. V.

1994-07-01

Phase relations in the system Mn-Rh-O are established at 1273 K by equilibrating different compositions either in evacuated quartz ampules or in pure oxygen at a pressure of 1.01 × 105 Pa. The quenched samples are examined by optical microscopy, X-ray diffraction, and energy-dispersive X-ray analysis (EDAX). The alloys and intermetallics in the binary Mn-Rh system are found to be in equilibrium with MnO. There is only one ternary compound, MnRh2O4, with normal spinel structure in the system. The compound Mn3O4 has a tetragonal structure at 1273 K. A solid solution is formed between MnRh2O4 and Mn3O4. The solid solution has the cubic structure over a large range of composition and coexists with metallic rhodium. The partial pressure of oxygen corresponding to this two-phase equilibrium is measured as a function of the composition of the spinel solid solution and temperature. A new solid-state cell, with three separate electrode compartments, is designed to measure accurately the chemical potential of oxygen in the two-phase mixture, Rh + Mn3-2xRh2xO4, which has 1 degree of freedom at constant temperature. From the electromotive force (emf), thermodynamic mixing properties of the Mn3O4-MnRh2O4 solid solution and Gibbs energy of formation of MnRh2O4 are deduced. The activities exhibit negative deviations from Raoult’s law for most of the composition range, except near Mn3O4, where a two-phase region exists. In the cubic phase, the entropy of mixing of the two Rh3+ and Mn3+ ions on the octahedral site of the spinel is ideal, and the enthalpy of mixing is positive and symmetric with respect to composition. For the formation of the spinel (sp) from component oxides with rock salt (rs) and orthorhombic (orth) structures according to the reaction, MnO (rs) + Rh2O3 (orth) → MnRh2O4 (sp), ΔG° = -49,680 + 1.56T (±500) J mol-1 The oxygen potentials corresponding to MnO + Mn3O4 and Rh + Rh2O3 equilibria are also obtained from potentiometric measurements on galvanic

Use of photogrammetry for taking the outline of patients in radiotherapy

International Nuclear Information System (INIS)

Borel, F.; Defer, J.; Aget, H.; Gallet, O.; Urbajtel, M.; Laugier, A.

1975-01-01

A photogrammetric method for taking the outline of patients in radiotherapy is described. Using only one couple of photographs, this fast and very precise process may reconstruct many transversal or longitudinal cross-sections, after a photographic storage of information. An automatic numerical reading of the outline may be directly fed into a computer for dosimetry [fr

Making Mn substitutional impurities in InAs using a scanning tunneling microscope.

Science.gov (United States)

Song, Young Jae; Erwin, Steven C; Rutter, Gregory M; First, Phillip N; Zhitenev, Nikolai B; Stroscio, Joseph A

2009-12-01

We describe in detail an atom-by-atom exchange manipulation technique using a scanning tunneling microscope probe. As-deposited Mn adatoms (Mn(ad)) are exchanged one-by-one with surface In atoms (In(su)) to create a Mn surface-substitutional (Mn(In)) and an exchanged In adatom (In(ad)) by an electron tunneling induced reaction Mn(ad) + In(su) --> Mn(In) + In(ad) on the InAs(110) surface. In combination with density-functional theory and high resolution scanning tunneling microscopy imaging, we have identified the reaction pathway for the Mn and In atom exchange.

Interplay between localization and magnetism in (Ga,Mn)As and (In,Mn)As

Science.gov (United States)

Yuan, Ye; Xu, Chi; Hübner, René; Jakiela, Rafal; Böttger, Roman; Helm, Manfred; Sawicki, Maciej; Dietl, Tomasz; Zhou, Shengqiang

2017-10-01

Ion implantation of Mn combined with pulsed laser melting is employed to obtain two representative compounds of dilute ferromagnetic semiconductors (DFSs): G a1 -xM nxAs and I n1 -xM nxAs . In contrast to films deposited by the widely used molecular beam epitaxy, neither Mn interstitials nor As antisites are present in samples prepared by the method employed here. Under these conditions the influence of localization on the hole-mediated ferromagnetism is examined in two DFSs with a differing strength of p-d coupling. On the insulating side of the transition, ferromagnetic signatures persist to higher temperatures in I n1 -xM nxAs compared to G a1 -xM nxAs with the same Mn concentration x . This substantiates theoretical suggestions that stronger p-d coupling results in an enhanced contribution to localization, which reduces hole-mediated ferromagnetism. Furthermore, the findings support strongly the heterogeneous model of electronic states at the localization boundary and point to the crucial role of weakly localized holes in mediating efficient spin-spin interactions even on the insulator side of the metal-insulator transition.

Synthesis and characterization of Mn-doped ZnO column arrays

International Nuclear Information System (INIS)

Yang Mei; Guo Zhixing; Qiu Kehui; Long Jianping; Yin Guangfu; Guan Denggao; Liu Sutian; Zhou Shijie

2010-01-01

Mn-doped ZnO column arrays were successfully synthesized by conventional sol-gel process. Effect of Mn/Zn atomic ratio and reaction time were investigated, and the morphology, tropism and optical properties of Mn-doped ZnO column arrays were characterized by SEM, XRD and photoluminescence (PL) spectroscopy. The result shows that a Mn/Zn atomic ratio of 0.1 and growth time of 12 h are the optimal condition for the preparation of densely distributed ZnO column arrays. XRD analysis shows that Mn-doped ZnO column arrays are highly c-axis oriented. As for Mn-doped ZnO column arrays, obvious increase of photoluminescence intensity is observed at the wavelength of ∼395 nm and ∼413 nm, compared to pure ZnO column arrays.

An outline review of numerical transport methods

International Nuclear Information System (INIS)

Budd, C.

1981-01-01

A brief review is presented of numerical methods for solving the neutron transport equation in the context of reactor physics. First the various forms of transport equation are given. Second, the various ways of classifying numerical transport methods are discussed. Finally each method (or class of methods) is outlined in turn. (U.K.)

Detection of stacking faults breaking the [110]/[110] symmetry in ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P)

International Nuclear Information System (INIS)

Kopecky, M.; Kub, J.; Maca, F.; Masek, J.; Pacherova, O.; Rushforth, A. W.; Gallagher, B. L.; Campion, R. P.; Novak, V.; Jungwirth, T.

2011-01-01

We report on high-resolution x-ray diffraction measurements of (Ga,Mn)As and (Ga,Mn)(As,P) epilayers. We observe a structural anisotropy in the form of stacking faults that are present in the (111) and (111) planes and absent in the (111) and (111) planes. They occupy 10 -2 %-10 -1 % of the ferromagnetic epilayer volume while no stacking faults are detected in the controlled, undoped GaAs epilayer. Full-potential density functional calculations provide additional evidence that the formation of the stacking faults is promoted by Mn attracted to these structural defects. The enhanced Mn density along the common [110] direction of the stacking fault planes produces a symmetry-breaking mechanism of a strength and sense that can account for the uniaxial [110]/[110] magnetocrystalline anisotropy of these ferromagnetic semiconductors.

Beryllium abundances in Hg-Mn stars

International Nuclear Information System (INIS)

Boesgaard, A.M.; Heacox, W.D.; Wolff, S.C.; Borsenberger, J.; Praderie, F.

1982-01-01

The Hg-Mn stars show anomalous line strengths of many chemical elements including Be. We have observed the Be ii resonance doublet at lambdalambda 3130, 3131 at 6.7 A mm -1 in 43 Hg-Mn stars and 10 normal stars in the same temperature range with the coude spectrograph of the 2.24 m University of Hawaii telescope at Mauna Kea. Measured equivalent widths of the two lines and/or the blend of the doublet have been compared with predictions from (1) LTE model atmospheres and (2) non-LTE line formation on non-LTE model atmospheres. (For strong Be ii lines, the LTE calculations result in more Be by factors of 2 to 4 than do the non-LTE calculations.) Overabundances of factors of 20--2 x 10 4 relative to solar have been found for 75% of the Hg-Mn stars. The 25% with little or no Be are typically among the cooler Hg-Mn stars, but for the stars with Be excesses, there is only marginal evidence for a correlationi of the size of the overabundance and temperature. It is suggested that diffusion driven by radiation pressure is responsible for the observed Be abundance anomalies

Mn valence state and electrode performance of perovskite-type ...

Indian Academy of Sciences (India)

increase in the oxidation state of Mn ions was due to the formation of Mn4+ ions and oxygen vacancies. The addition of Cu ions to LSM systems could lead to enhanced electrode performance for oxygen reduction reactions originating from the change in valence of Mn ions. Keywords. Cu-doped LSM; electrical conductivity; ...

Ferri-magnetic order in Mn induced spinel Co{sub 3−x}Mn{sub x}O{sub 4} (0.1≤x≤1.0) ceramic compositions

Energy Technology Data Exchange (ETDEWEB)

Meena, P.L., E-mail: plmeena@gmail.com [Department of Physics, Deen Dayal Upadhyaya College (University of Delhi), Shivaji Marg, Karampura, New Delhi 110015 (India); Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, North Campus, Delhi 110007 (India); Singh, M.R. [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400085 (India); Kumar, Ashok; Singh, S.P. [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Kumar, Ravi [Beant College of Engineering and Technology, Gurdaspur, Punjab 143521 (India)

2016-04-01

We report structural and magnetic properties of spinel Co{sub 3−x}Mn{sub x}O{sub 4} (x=0.1–1.0) synthesized by solid state reaction technique. Rietveld refinement analysis of X-ray diffraction (XRD) data, revealed the formation of polycrystalline single phase Co{sub 3−x}Mn{sub x}O{sub 4} without any significant structural change in cubic crystal symmetry with Mn substitution, except change in lattice parameter. Temperature dependent magnetization data show changes in magnetic ordering temperature, indicating formation of antiferromagnetic (AFM) and ferrimagnetic (FM) phase at low Mn concentration (x≤0.3) and well-defined FM phase at high Mn concentration (x≥0.5). The isothermal magnetization records established an AFM/FM mixed phase for composition ranging 0.10.5. - Highlights: • Synthesis of single phase polycrystalline Co{sub 3−x}Mn{sub x}O{sub 4} ceramic. • Change in magnetic ordering with varying Mn concentration. • The complex spin distribution is contributing to FM ordering with higher Mn.

Surfaces and their effect on the magnetic properties of polycrystalline hollow γ-Mn{sub 2}O{sub 3} and MnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bah, Mohamed A. [Department of Materials Science and Engineering, Newark, DE (United States); Jaffari, G. Hassnain [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Khan, F.A. [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh); Shah, S. Ismat, E-mail: ismat@udel.edu [Department of Materials Science and Engineering, Newark, DE (United States); Department of Physics and Astronomy, Newark, DE (United States)

2016-07-01

Graphical abstract: Polycrystalline hollow nanoparticles composed of γ-Mn{sub 2}O{sub 3} and MnO were grown in an inert gas condensation system. Particles where found to range from 15 nm to 30 nm in diameter with different void sizes. Both γ-Mn{sub 2}O{sub 3} and MnO phases were found to exist in a single nanoparticle, and in close proximity. The oxides had different size and random lattice orientations. The morphology of the nanoparticles with the specific oxide is believed to be the leading cause for the observed high coercivity and exchange bias. - Highlights: • Polycrystalline hollow nanoparticles composed of γ-Mn{sub 2}O{sub 3} (ferrimagnetic(FiM)) and MnO (antiferromagnetic(AFM)) crystallites. • γ-Mn{sub 2}O{sub 3} and MnO co-exist in a single nanoparticles. • FC loops exhibited noticeably larger coercivity compared to the ZFC loops. • Compared to the core/shell counter parts, large coercivity and exchange bias, up to 11 kOe and 7 kOe, respectively, were observed at low temperature. • Strong coupling between the FiM and AFM phases. • Large horizontal and vertical shifts. - Abstract: Manganese oxide nanoparticles were prepared in an inert gas condensation system. X-ray Diffraction (XRD) studies revealed presence of multiple manganese oxide phases while high resolution transmission electron microscopy (HRTEM) showed polycrystalline hollow nanoparticle morphology. The additional inner surface of the hollow nanoparticle directly affect the magnetic properties of these particles. Combined physical structure, electronic structure and magnetic susceptibility analyses led to the conclusion that the prepared nanoparticles are polycrystalline and composed of γ-Mn{sub 2}O{sub 3} and MnO crystallites. Magnetic study found a sharp peak around 38 K with no frequency dependence in the AC susceptibility measurement. Large coercivity (H{sub C}) and exchange bias (H{sub EB}) fields, up to 11 kOe and 7 kOe, respectively, were observed below the order

Magnetic interactions in martensitic Ni-Mn based Heusler systems

Energy Technology Data Exchange (ETDEWEB)

Aksoy, Seda

2010-04-22

In this work, magnetic, magnetocaloric and structural properties are investigated in Ni-Mn-based martensitic Heusler alloys with the aim to tailor these properties as well as to understand in detail the magnetic interactions in the various crystallographic states of these alloys. We choose Ni{sub 50}Mn{sub 34}In{sub 16} as a prototype which undergoes a martensitic transformation and exhibits field-induced strain and the inverse magnetocaloric effect. Using the structural phase diagram of martensitic Ni-Mn-based Heusler alloys, we substitute gallium and tin for indium to carry these effects systematically closer to room temperature by shifting the martensitic transformation. A magneto-calorimeter is designed and built to measure adiabatically the magnetocaloric effect in these alloys. The temperature dependence of strain under an external magnetic field is studied in Ni{sub 50}Mn{sub 50-x}Z{sub x} (Z: Ga, Sn, In and Sb) and Ni{sub 50}Mn{sub 34}In{sub 16-x}Z{sub x} (Z: Ga and Sn). An argument based on the effect of the applied magnetic field on martensite nucleation is adopted to extract information on the direction of the magnetization easy axis in the martensitic unit cell in Heusler alloys. Parallel to these studies, the structure in the presence of an external field is also studied by powder neutron diffraction. It is demonstrated that martensite nucleation is influenced by cooling the sample under a magnetic field such that the austenite phase is arrested within the martensitic state. The magnetic interactions in Ni{sub 50}Mn{sub 37}Sn{sub 13} and Ni{sub 50}Mn{sub 40}Sb{sub 10} are characterized by using neutron polarization analysis. Below the martensitic transformation temperature, M{sub s}, an antiferromagnetically correlated state is found. Ferromagnetic resonance experiments are carried out on Ni{sub 50}Mn{sub 37}Sn{sub 13} and Ni{sub 50}Mn{sub 34}In{sub 16} to gain more detailed information on the nature of the magnetic interactions. The experimental

Simple and Practical Efficiency Lessons

Science.gov (United States)

Kolpin, Van

2018-01-01

The derivation of conditions necessary for Pareto efficient production and exchange is a lesson frequently showcased in microeconomic theory textbooks. Traditional delivery of this lesson is, however, limited in its scope of application and can be unnecessarily convoluted. The author shows that the universe of application is greatly expanded and a…

Magnetic and electronic properties of SrMnO3 thin films

Science.gov (United States)

Mandal, Arup Kumar; Panchal, Gyanendra; Choudhary, R. J.; Phase, D. M.

2018-05-01

Single phase hexagonal bulk SrMnO3 (SMO) was prepared by solid state route and it was used for depositing thin films by pulsed laser deposition (PLD) technique on single crystalline (100) oriented SrTiO3 (STO) substrate. X-ray diffraction shows that the thin film is deposited in cubic SrMnO3 phase. From X-ray absorption at the Mn L edge we observed the mixed valency of Mn (Mn3+& Mn4+) due to strain induced by the lattice mismatching between SMO and STO. Due to this mixed valency of Mn ion in SMO film, the ferromagnetic nature is observed at lower temperature because of double exchange. After post annealing with very low oxygen partial pressure, magnetic and electronic property of SMO films are effectively modified.

Spatial structure of single and interacting Mn acceptors in GaAs

Science.gov (United States)

Koenraad, Paul

2005-03-01

Ferromagnetic semiconductors such as Ga1-xMnxAs are receiving a lot of attention at the moment because of their application in spintronic devices. However, despite intense study of deep acceptors in III-V semiconductors such as MnGa, little information has been obtained on their electronic properties at the atomic scale. Yet the spatial shape of the Mn acceptor state will influence the hole-mediated Mn-Mn coupling and thus all of the magnetic properties of ferromagnetic semiconductors such as Ga1-xMnxAs. This study presents an experimental and theoretical description of the spatial symmetry of the Mn acceptor wave-function in GaAs. We present measurements of the spatial mapping of the anisotropic wavefunction of a hole localized at a Mn acceptor. To achieve this, we have used the STM tip not only to image the Mn acceptor but also to manipulate its charge state A^0/A^- at room temperature. Within an envelope function effective mass model (EFM) the anisotropy in the acceptor wave-function can be traced to the influence of the cubic symmetry of the GaAs crystal which selects specific d-states that mix into the ground state due to the spin-orbit interaction in the valence band. Comparison with calculations based on a tight-binding model (TBM) for the Mn acceptor structure supports this conclusion. Using the same experimental and theoretical approach we furthermore explored the interaction between Mn acceptors directly by analyzing close Mn-Mn pairs, which were separated by less than 2 nm. We will discuss some implications of these results for Mn delta-doped layers grown on differently oriented growth surfaces.

Planning geometry lessons with learning platforms

DEFF Research Database (Denmark)

Tamborg, Andreas Lindenskov

mathematics teachers’ joint planning of a lesson in geometry with a learning platform called Meebook is analyzed using the instrumental approach. It is concluded that the interface in Meebook orients the teachers work toward what the students should do rather than what they should learn, although the latter......This paper investigates how mathematics teachers plan lessons with a recently implemented Danish learning platform designed to support teachers in planning lessons in line with a recent objective-oriented curriculum. Drawing on data from observations of and interviews with teachers, three...... is a key intention behind the implementation of the platform. It is also concluded that when the teachers succeed in using learning objectives actively in their planning, the objectives support the teachers in designing lessons that correspond with their intentions. The paper concludes with a discussion...

Manganese superoxide dismutase (MnSOD catalyzes NO-dependent tyrosine residue nitration

Directory of Open Access Journals (Sweden)

SRDJAN STOJANOVIC

2005-04-01

Full Text Available The peroxynitrite-induced nitration of manganese superoxide dismutase (MnSOD tyrosine residue, which causes enzyme inactivation, is well established. This led to suggestions that MnSOD nitration and inactivation in vivo, detected in various diseases associated with oxidative stress and overproduction of nitric monoxide (NO, conditions which favor peroxynitrite formation, is also caused by peroxynitrite. However, our previous in vitro study demonstrated that exposure of MnSOD to NO led to NO conversion into nitrosonium (NO+ and nitroxyl (NO– species, which caused enzyme modifications and inactivation. Here it is reported that MnSOD is tyrosine nitrated upon exposure to NO, as well as that MnSOD nitration contributes to inactivation of the enzyme. Collectively, these observations provide a compelling argument supporting the generation of nitrating species in MnSOD exposed to NO and shed a new light on MnSOD tyrosine nitration and inactivation in vivo. This may represent a novel mechanism by which MnSOD protects cell from deleterious effects associated with overproduction of NO. However, extensive MnSOD modification and inactivation associated with prolonged exposure to NO will amplify the toxic effects caused by increased cell superoxide and NO levels.

Microstructure of (Ga,Mn)As/GaAs digital ferromagnetic heterostructures

International Nuclear Information System (INIS)

Kong, X.; Trampert, A.; Guo, X.X.; Kolovos-Vellianitis, D.; Daeweritz, L.; Ploog, K.H.

2005-01-01

We report on the microstructure of (Ga,Mn)As digital ferromagnetic heterostructures grown on GaAs (001) substrates by low-temperature molecular-beam epitaxy. The Mn concentration and the As 4 /Ga beam equivalent pressure (BEP) ratio are varied in the samples containing periods of Mn sheets separated by thin GaAs spacer layers. Transmission electron microscopy studies reveal that decreasing the Mn doping concentration and reducing the BEP ratio lead to smaller composition fluctuations of Mn and more homogeneous (Ga,Mn)As layers with abrupt interfaces. Planar defects are found as the dominant defect in these heterostructures and their density is related to the magnitude of the composition fluctuation. These defects show a noticeable anisotropy in the morphologic distribution parallel to the orthogonal [110] and [110] direction. Along the [110] direction, they are stacking faults, which are preferentially formed in V-shaped pairs and nucleate at the interfaces between (Ga,Mn)As and GaAs layers. Along the [110] direction, the planar defects are isolated thin twin lamellae. The character of the planar defects and their configuration are analyzed in detail

Spin coherence in a Mn{sub 3} single-molecule magnet

Energy Technology Data Exchange (ETDEWEB)

Abeywardana, Chathuranga [Department of Chemistry, University of Southern California, Los Angeles, California 90089 (United States); Mowson, Andrew M.; Christou, George [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States); Takahashi, Susumu, E-mail: susumu.takahashi@usc.edu [Department of Chemistry, University of Southern California, Los Angeles, California 90089 (United States); Department of Physics, University of Southern California, Los Angeles, California 90089 (United States)

2016-01-25

Spin coherence in single crystals of the spin S = 6 single-molecule magnet (SMM) [Mn{sub 3}O(O{sub 2}CEt){sub 3}(mpko){sub 3}]{sup +} (abbreviated Mn{sub 3}) has been investigated using 230 GHz electron paramagnetic resonance spectroscopy. Coherence in Mn{sub 3} was uncovered by significantly suppressing dipolar contribution to the decoherence with complete spin polarization of Mn{sub 3} SMMs. The temperature dependence of spin decoherence time (T{sub 2}) revealed that the dipolar decoherence is the dominant source of decoherence in Mn{sub 3} and T{sub 2} can be extended up to 267 ns by quenching the dipolar decoherence.

Ideas and Inspirations: Good News about Diabetes Prevention and Management in Indian Country

Medline Plus

Full Text Available ... Educators and Community Members Diabetes Educator Tools Diabetes Education Lesson Plan Outlines Integrating Case Management Into Your Practice [PDF – ... has to offer for those who provide diabetes education. Find Guides for Diabetes ... Online Lesson Plan Outlines for Educators New or seasoned educators can ...

Synthesis, characterization and electrochemical performance of Al-substituted Li_2MnO_3

International Nuclear Information System (INIS)

Torres-Castro, Loraine; Shojan, Jifi; Julien, Christian M.; Huq, Ashfia; Dhital, Chetan; Paranthaman, Mariappan Parans; Katiyar, Ram S.; Manivannan, Ayyakkannu

2015-01-01

Graphical abstract: Comparison of the cycling performances for pure Li_2MnO_3 and Al-substituted Li_2MnO_3 compounds at a current density of 10 mAh g"−"1 for 100 cycles. Al-substitution increases the spinel phase and hence improves the cycling behavior. - Highlights: • Pure and Al-doped Li_2MnO_3 compounds were synthesized by a Pechini method. • Presence of monoclinic and spinel phases confirmed by Raman and Neutron diffraction. • Al substitution occurs at both Mn and Li sites in Li_2MnO_3 structure. • Al substitution reduces Mn valence state and promotes spinel phase formation. • Stable cycling capacity of 70 mAh g"−"1 was observed for nominal Li_0_._5Al_0_._5MnO_3. - Abstract: 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_._1_7MnO_3, Li_1_._0Al_0_._3_3MnO_3 and Li_0_._5Al_0_._5MnO_3 were synthesized by a sol–gel Pechini method. All the samples were characterized with XRD, Raman, XPS, SEM, Tap density and BET analyzer. XRD patterns indicated the presence of monoclinic phase for pristine Li_2MnO_3 and mixed monoclinic/spinel phases (Li_2_−_xMn_1_−_yAl_x_+_yO_3_+_z) for Al-substituted Li_2MnO_3 compounds. The Al substitution seems to occur both at Li and Mn sites, which could explain the presence of spinel phase. XPS analysis for Mn 2p orbital reveals a significant decrease in binding energy for Li_1_._0Al_0_._3_3MnO_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_._1_7MnO_3, 58 mAh g"−"1 for Li_1_._0Al_0_._3_3MnO_3 and 74 mAh g"−"1 for Li_0_._5Al_0_._5MnO_3 were obtained. Aluminum substitutions increased the formation of spinel phase which is responsible for cycling.

Masterwork Art Lesson: Kandinsky Watercolors.

Science.gov (United States)

LiPira, Michael

2003-01-01

Presents an art lesson used with sixth-grade students which also can be used with other grade levels. Explains that the artwork of Wassily Kandinsky served as inspiration for this lesson. Explains that the students learned about abstract art and used watercolors to create their own paintings in the style of Kandinsky. (CMK)

Bead Game Simulation. Lesson Plan.

Science.gov (United States)

Ripp, Ken

This lesson plan offers students the opportunity to participate in the three basic economic systems (market, command, and tradition). By working in each of the systems, students will internalize the fundamental values present in each system and will gain insights into the basic advantages and disadvantages of each system. The lesson plan provides…

Magnetocaloric effect in Heusler alloys Ni50Mn34In16 and Ni50Mn34Sn16

Science.gov (United States)

Sharma, V. K.; Chattopadhyay, M. K.; Kumar, Ravi; Ganguli, Tapas; Tiwari, Pragya; Roy, S. B.

2007-12-01

We present results of detailed ac susceptibility, magnetization and specific heat measurements in Heusler alloys Ni50Mn34In16 and Ni50Mn34Sn16. These alloys undergo a paramagnetic to ferromagnetic transition around 305 K, which is followed by a martensitic transition in the temperature regime around 220 K. Inside the martensite phase both the alloys show signatures of field-induced transition from martensite to austenite phase. Both field- and temperature-induced martensite-austenite transitions are relatively sharp in Ni50Mn34In16. We estimate the isothermal magnetic entropy change and adiabatic temperature change across the various phase transitions in these alloys and investigate the possible influence of these transitions on the estimated magnetocaloric effect. The sharp martensitic transition in Ni50Mn34In16 gives rise to a comparatively large inverse magnetocaloric effect across this transition. On the other hand the magnitudes of the conventional magnetocaloric effect associated with the paramagnetic to ferromagnetic transition are quite comparable in these alloys.

Synthesis and characterization of Mn-doped ZnO diluted magnetic semiconductors

Energy Technology Data Exchange (ETDEWEB)

Abdel-Galil, A. [Solid State Physics and Accelerators Department, NCRRT, Atomic Energy Authority, Cairo (Egypt); Balboul, M.R., E-mail: m_balboul@yahoo.com [Solid State Physics and Accelerators Department, NCRRT, Atomic Energy Authority, Cairo (Egypt); Sharaf, A. [Radiation Engineering Department, NCRRT, Atomic Energy Authority, Cairo (Egypt)

2015-11-15

In the present work undoped and Mn doped ZnO nanoparticles (ZnO:Mn), diluted magnetic semiconductors, were successfully synthesized by the sol–gel method at room temperature. The morphology of ZnO nanoparticles constituted by flower-like structures with hexagonal morphologies that changed significantly after the incorporation of Mn. Rietveld refinements results showed that Mn ions are successfully doped into ZnO matrix without altering its wurtzite phase. Meanwhile, Raman spectroscopy analyses confirm the wurtzite structure of undoped ZnO and ZnO:Mn nanoparticles. The lattice parameters increase with increasing Mn content due to the large ionic radius of Mn{sup 2+} compared to that of Zn{sup 2+}. Electron spin resonance measurements were performed to gain information about oxidation state and site occupancy of the magnetic Mn ions in the ZnO lattice. Moreover, UV–vis absorption spectra have been utilized to calculate the optical band gap of the undoped ZnO and ZnO:Mn nanoparticles before and after different γ-irradiation doses. The band gap of ZnO:Mn (2%) is 2.62 eV which is noticeably smaller than the 3.26 eV of undoped ZnO. The thermal decomposition properties of the prepared nanoparticle samples were also studied using simultaneous Thermogravimetric analysis in temperature range from 30 to 500 °C.

Tailoring luminescence properties of TiO2 nanoparticles by Mn doping

International Nuclear Information System (INIS)

Choudhury, B.; Choudhury, A.

2013-01-01

TiO 2 nanoparticles are doped with three different concentrations of Mn, 2%, 4% and 6% respectively. Absorption edge of TiO 2 is shifted from UV to visible region on amplification of Mn content. Room temperature photoluminescence spectra, excited at 320 nm, exhibit band edge and visible emission peaks associated with self trapped excitons, oxygen defects, etc. Doping of Mn increases the width and decreases the intensity of the UV emission peak. Potential fluctuations of impurities increase the width and auger type non-radiative recombination decreases the intensity of the UV emission peak. The intensity ratio of the UV to defect emission band decreases on doping, indicating degradation of structural quality. Excitation of pure and doped nanoparticles at 390 nm results in Mn 2+ emission peaks at 525 nm and 585 nm respectively. Photoluminescence excitation spectra also indicate the presence of Mn 2+ in the crystalline environment of TiO 2 . The oxygen defects and Mn related impurities act as efficient trap centers and increases the lifetime of the charge carriers. -- Highlights: ► Doping of Mn increases the d-spacing of TiO 2 nanoparticles. ► Characteristic d–d electronic transition of Mn 2+ is observed in the absorption spectra. ► Doping of Mn quenches the UV and visible emission peaks of TiO 2 . ► Photoexcitation at 390 nm generates emission peaks of Mn 2+

Implementing US Department of Energy lessons learned programs. Volume 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-08-01

The DOE Lessons Learned Handbook is a two-volume publication developed to supplement the DOE Lessons Learned Standard (DOE-STD-7501-95) with information that will organizations in developing or improving their lessons learned programs. Volume 1 includes greater detail than the Standard in areas such as identification and documentation of lessons learned; it also contains sections on specific processes such as training and performance measurement. Volume 2 (this document) contains examples of program documents developed by existing lessons learned programs as well as communications material, functional categories, transmittal documents, sources of professional and industry lessons learned, and frequently asked questions about the Lessons Learned List Service.

Bimetallic Co-Mn Perovskite Fluorides as Highly-Stable Electrode Materials for Supercapacitors.

Science.gov (United States)

Shi, Wei; Ding, Rui; Li, Xudong; Xu, Qilei; Ying, Danfeng; Huang, Yongfa; Liu, Enhui

2017-11-02

Bimetallic Co-Mn perovskite fluorides (KCo x Mn 1-x F 3 , denoted as K-Co-Mn-F) with various Co/Mn ratios (1:0, 12:1, 6:1, 3:1, 1:1, 1:3, 0:1) were prepared through a one-pot solvothermal strategy and further used as electrode materials for supercapacitors. The optimal K-Co-Mn-F candidate (Co/Mn=6:1) showed a size range of 0.1-1 μm and uniform elemental distribution; exhibiting small changes in XRD peaks and XPS binding energy in comparison to the bare K-Co-F and K-Mn-F, due to the structural/electronic effects. Owing to the stronger synergistic effect of Co/Mn redox species, the K-Co-Mn-F (Co/Mn=6:1) electrode exhibited superior specific capacity and rate behavior (113-100 C g -1 at 1-16 Ag -1 ) together with excellent cycling stability (118 % for 5000 cycles at 8 Ag -1 ), and the activated carbon (AC)//K-Co-Mn-F (Co/Mn=6:1) asymmetric capacitor showed superior energy and power densities (8.0-2.4 Wh kg -1 at 0.14-8.7 kW kg -1 ) along with high cycling stability (90 % for 10 000 cycles at 5 Ag -1 ). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

California's population geography: lessons for a fourth grade class.

Science.gov (United States)

Rushdoony, H A

1978-11-01

Purpose of this paper is to present a model for teaching fourth grade children some aspects of the population geography of California from a nontextual approach. The objective is to interest and instruct children in the mobility of the people, and on the reasons why so many families have moved to California from other states. Students should be alerted not only to internal migration problems, but to the excess of births over deaths. Materials necessary for the lessons are transparencies, overhead projector, marking pencils, chalk and chalkboard. After showing the students that California population has approximately doubled every 20 years, the students should be encouraged to find reasons explaining why people have moved to the state, should be able to categorize those reasons under the terms industrial/manufacturing, agricultural, urban or recreational, should learn how to plot population distribution on a California regional outline map, and should attempt to explain why certain parts of California are more popular than others. The teaching model described in this paper may be replicated with modfications for any grade level and area of study.

Identification of everyday objects on the basis of Gaborized outline versions.

Science.gov (United States)

Sassi, Michaël; Vancleef, Kathleen; Machilsen, Bart; Panis, Sven; Wagemans, Johan

2010-01-01

Using outlines derived from a widely used set of line drawings, we created stimuli geared towards the investigation of contour integration and texture segmentation using shapes of everyday objects. Each stimulus consisted of Gabor elements positioned and oriented curvilinearly along the outline of an object, embedded within a larger Gabor array of homogeneous density. We created six versions of the resulting Gaborized outline stimuli by varying the orientations of elements inside and outside the outline. Data from two experiments, in which participants attempted to identify the objects in the stimuli, provide norms for identifiability and name agreement, and show differences in identifiability between stimulus versions. While there was substantial variability between the individual objects in our stimulus set, further analyses suggest a number of stimulus properties which are generally predictive of identification performance. The stimuli and the accompanying normative data, both available on our website (http://www.gestaltrevision.be/sources/gaboroutlines), provide a useful tool to further investigate contour integration and texture segmentation in both normal and clinical populations, especially when top-down influences on these processes, such as the role of prior knowledge of familiar objects, are of main interest.

Physically active academic lessons in elementary children.

Science.gov (United States)

Bartholomew, John B; Jowers, Esbelle M

2011-06-01

Although schools are an ideal location to conduct interventions that target children, the emphasis on standardized testing makes it difficult to implement interventions that do not directly support academic instruction. In response, physically active academic lessons have been developed as a strategy to increase physical activity while also addressing core educational goals. Texas I-CAN! is one incarnation of this approach. We will review the on-going research on the impact of these active lessons on: teacher implementation, child step count, child attention control, and academic performance. The collected studies support the impact of physically active academic lessons on each area of interest. If these data can be replicated, it suggests that teachers might find these lessons of benefit to their primary role as educators, which should ease dissemination of these and other physically active lessons in elementary schools. Copyright © 2011 Elsevier Inc. All rights reserved.

Mid - infrared transmission of polycrystalline (LaSr) (MnNi)O3

International Nuclear Information System (INIS)

Laksanawati, W. D.; Kurniawan, B.; Saptari, S. A.

2016-01-01

Polycrystalline (LaSr)(MnNi)O 3 was shintesized using sol gel methods with nitrat precursors La(NO 3 ) 3 , Sr(NO 3 ) 2 , Mn(NO 3 ) 2 .4H 2 O, and Ni(NO3)2.6H2O and the different heating process. Sample (LaSr)(MnNi)O 3 with chemical formulation La 0,67 Sr 0,33 Mn 1-x Ni x O 3 with × = 0,05 and 0,10. We report the crystallite structure of La 0,67 Sr 0,33 Mn 1-x Ni x O 3 with x= 0,00 and 0,10 are single phase with characterization by X-ray diffraction. Refinement has result that crystallite size of La 0,67 Sr 0,33 Mn 0,95 Ni 0,05 O 3 is 24,67 and La 0,67 Sr 0,33 Mn 0,9 Ni 0,1 O 3 is 21,84 with crystallite system rombohedral, it show us that increasing at Ni composition influence of decreased crystallite size. Sampel (LaSr)(MnNi)O3 has been characterization with Fourier Transform Infrared with range of wave number from 450 to 4000 cm -1 were chategories at mid infrared wave. The FTIR pattern show to us that the Mn-O-Mn bounded has absorp infrared at wave number 605 cm -1 and the dominant peak at wave number 3750 cm -1 caused the hidroxy compound in sampel La 0,67 Sr 0,33 Mn 0,95 Ni 0,05 O 3 . (paper)

Reduction of mixed Mn-Zr oxides: in situ XPS and XRD studies.

Science.gov (United States)

Bulavchenko, O A; Vinokurov, Z S; Afonasenko, T N; Tsyrul'nikov, P G; Tsybulya, S V; Saraev, A A; Kaichev, V V

2015-09-21

A series of mixed Mn-Zr oxides with different molar ratios Mn/Zr (0.1-9) have been prepared by coprecipitation of manganese and zirconium nitrates and characterized by X-ray diffraction (XRD) and BET methods. It has been found that at concentrations of Mn below 30 at%, the samples are single-phase solid solutions (MnxZr1-xO2-δ) based on a ZrO2 structure. X-ray photoelectron spectroscopy (XPS) measurements showed that manganese in these solutions exists mainly in the Mn(4+) state on the surface. An increase in Mn content mostly leads to an increase in the number of Mn cations in the structure of solid solutions; however, a part of the manganese cations form Mn2O3 and Mn3O4 in the crystalline and amorphous states. The reduction of these oxides with hydrogen was studied by a temperature-programmed reduction technique, in situ XRD, and near ambient pressure XPS in the temperature range from 100 to 650 °C. It was shown that the reduction of the solid solutions MnxZr1-xO2-δ proceeds via two stages. During the first stage, at temperatures between 100 and 500 °C, the Mn cations incorporated into the solid solutions MnxZr1-xO2-δ undergo partial reduction. During the second stage, at temperatures between 500 and 700 °C, Mn cations segregate on the surface of the solid solution. In the samples with more than 30 at% Mn, the reduction of manganese oxides was observed: Mn2O3 → Mn3O4 → MnO.

A Comparison of Two Yeast MnSODs: Mitochondrial Saccharomyces cerevisiae versus Cytosolic Candida albicans

International Nuclear Information System (INIS)

Sheng, Y.; Cabelli, D.; Stich, T.A.; Barnese, K.; Gralla, E.B.; Cascio, D.; Britt, R.D.; Valentine, J.S.

2011-01-01

Human MnSOD is significantly more product-inhibited than bacterial MnSODs at high concentrations of superoxide (O 2 - ). This behavior limits the amount of H 2 O 2 produced at high [O 2 - ]; its desirability can be explained by the multiple roles of H 2 O 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 predominantly in the reduced state (unlike most other MnSODs). At high [O 2 - ], 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 3+ species in yeast Mn 3+ SODs, including the well-characterized 5-coordinate Mn 3+ species and a 6-coordinate L-Mn 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 2 - ].

A facile route to synthesize multiporous MnCo2O4 and CoMn2O4 spinel quasi-hollow spheres with improved lithium storage properties

Science.gov (United States)

Li, Jingfa; Xiong, Shenglin; Li, Xiaowei; Qian, Yitai

2013-02-01

A facile and general way for the synthesis of porous and hollow complex oxides is highly desirable owing to their significant applications for energy storage and other fields. In this contribution, uniform Mn0.33Co0.67CO3 and Co0.33Mn0.67CO3 microspheres are firstly fabricated solvothermally just by tuning the molar ratio of Mn and Co. Subsequently, the growth of multiporous MnCo2O4 and CoMn2O4 quasi-hollow microspheres by topotactic chemical transformation from the corresponding precursors are realized through a non-equilibrium heat treatment process. Topotactic conversion further demonstrated that the much larger CoMn2O4 pores than those of MnCo2O4 are possibly due to the longer transfer distance of ions. When evaluated as anode materials for LIBs (lithium ion batteries), after 25 cycles at a current density of 200 mA g-1, the resultant MnCo2O4 and CoMn2O4 quasi-hollow microspheres possessed reversible capacities of 755 and 706 mA h g-1, respectively. In particular, the MnCo2O4 samples could deliver a reversible capacity as high as 610 mA h g-1 even at a higher current density of 400 mA g-1 with excellent electrochemical stability after 100 cycles of testing, indicating its potential application in LIBs. We believe that such good performance results from the appropriate pore size and quasi-hollow nature of MnCo2O4 microspheres, which can effectively buffer the large volume variation of anodes based on the conversion reaction during Li+ insertion/extraction. The present strategy is simple but very effective, and due to its versatility, it can be extended to other binary, even ternary complex metal oxides with high-performance in LIBs.A facile and general way for the synthesis of porous and hollow complex oxides is highly desirable owing to their significant applications for energy storage and other fields. In this contribution, uniform Mn0.33Co0.67CO3 and Co0.33Mn0.67CO3 microspheres are firstly fabricated solvothermally just by tuning the molar ratio of Mn and Co

MCD spectroscopy of hexanuclear Mn(III) salicylaldoxime single-molecule magnets.

Science.gov (United States)

Bradley, Justin M; Thomson, Andrew J; Inglis, Ross; Milios, Constantinos J; Brechin, Euan K; Piligkos, Stergios

2010-11-07

The hexanuclear cages [Mn(6)O(2)(R-sao)(6)L(2)(EtOH)(x)(H(2)O)(y)] "Mn(6)" behave as single-molecule magnets (SMMs) below a characteristic blocking temperature. As with [Mn(12)O(12)(O(2)CR)(16)(H(2)O)(4)] "Mn(12)" the electronic absorption spectra are rather featureless, yielding little information on the electronic structure of the magnetic ions. Low temperature Magnetic Circular Dichroism (MCD) spectra afford greater resolution of the optical transitions and also probe the magnetic properties of the system. Both the ground state spin and blocking temperature of the Mn(6) cages are determined by subtle structural perturbations of a generic Mn(6)O(2) core. Absorbance and MCD spectra are reported for [Mn(6)O(2)(Et-sao)(6){O(2)CPh(Me)(2)}(2)(EtOH)(6)] (1), [Mn(6)O(2)(Et-sao)(6){O(2)CPh}(2)(EtOH)(4)(H(2)O)(2)] (2), [Mn(6)O(2)(sao)(6){O(2)CPh}(2)(EtOH)(4)]·EtOH (3) and the trinuclear precursor [Mn(3)O(Et-sao)(3)(MeOH)(3)](ClO(4)) (4) cast into polymer film. SMM behaviour has previously been observed using magnetic susceptibility measurements on powder and single-crystal samples. The ligand field environment of the magnetic ions is assumed to be similar in (1) and (2) and their different blocking temperatures are attributed to the magnitude of the effective exchange constant. The MCD spectra of (1) and (2), in which the ground state spin S = 12, show that the ligand field environments of the Mn ions are almost identical and that magnetic hysteresis persists for isolated molecules when crystal packing forces are removed. The subtle structural differences between (1) and (2) are manifested in the field dependence of the MCD response at different wavelengths that reflect changes in band polarisation. The MCD spectrum of (3) contains features not apparent in those of (1) and (2). These are attributed to 5-coordinate Mn(iii), which is unique to (3) among the compounds studied. (3) has ground state spin S = 4, a lower blocking temperature and consequently no observable

Lesson Study and History Education

Science.gov (United States)

Halvorsen, Anne-Lise; Kesler Lund, Alisa

2013-01-01

This article examines the experiences of a group of fifth-grade teachers who used lesson study, a teacher-driven form of professional development, to teach history in a project supported by a Teaching American History Grant. The project addressed the following questions: What does a lesson study cycle for history education look like? What…

Synthesis and characterization of single-phase Mn-doped ZnO

Energy Technology Data Exchange (ETDEWEB)

Chattopadhyay, S.; Dutta, S.; Banerjee, A.; Jana, D. [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009, West Bengal (India); Bandyopadhyay, S., E-mail: sbaphy@caluniv.ac.i [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009, West Bengal (India); Chattopadhyay, S. [Department of Physics, Taki Government College, Taki 743 429, West Bengal (India); Sarkar, A. [Department of Physics, Bangabasi Morning College, 19 Rajkumar Chakraborty Sarani, Kolkata 700 009, West Bengal (India)

2009-05-01

Different samples of Zn{sub 1-x}Mn{sub x}O 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{sub 2}O{sub 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 (tau{sub 1}) at defect site (tau{sub 2}) and average (tau{sub av}) increases with milling time.

Photoluminescence of crystalline and disordered BTO:Mn powder: Experimental and theoretical modeling

International Nuclear Information System (INIS)

Gurgel, M.F.C.; Espinosa, J.W.M.; Campos, A.B.; Rosa, I.L.V.; Joya, M.R.; Souza, A.G.; Zaghete, M.A.; Pizani, P.S.; Leite, E.R.; Varela, J.A.; Longo, E.

2007-01-01

Disordered and crystalline Mn-doped BaTiO 3 (BTO:Mn) powders were synthesized by the polymeric precursor method. After heat treatment, the nature of visible photoluminescence (PL) at room temperature in amorphous BTO:Mn was discussed, considering results of experimental and theoretical studies. X-ray diffraction (XRD), PL, and UV-vis were used to characterize this material. Rietveld refinement of the BTO:Mn from XRD data was used to built two models, which represent the crystalline BTO:Mn (BTO:Mn c ) and disordered BTO:Mn (BTO:Mn d ) structures. Theses models were analyzed by the periodic ab initio quantum mechanical calculations using the CRYSTAL98 package within the framework of density functional theory at the B3LYP level. The experimental and theoretical results indicated that PL is related with the degree of disorder in the BTO:Mn powders and also suggests the presence of localized states in the disordered structure

Value pricing pilot program : lessons learned

Science.gov (United States)

2008-08-01

This "Lessons Learned Report" provides a summary of projects sponsored by the Federal Highway Administration's (FHWA's) Congestion and Value Pricing Pilot Programs from 1991 through 2006 and draws lessons from a sample of projects with the richest an...

Increasing Mn substitution in magnetic semiconductors through controlled ambient annealing processes

Energy Technology Data Exchange (ETDEWEB)

Hollingsworth, J. [Materials Science Program, Department of Mechanical and Aerospace Engineering, UC San Diego, La Jolla, CA 92093-0411 (United States); Bandaru, P.R. [Materials Science Program, Department of Mechanical and Aerospace Engineering, UC San Diego, La Jolla, CA 92093-0411 (United States)], E-mail: pbandaru@ucsd.edu

2008-06-25

We report on a controlled ambient annealing technique aimed at increasing the amount of Mn incorporation in III-V semiconductors. The aim is to reduce the number of hole carrier and magnetic element compensating entities, such as Mn interstitials and anti-site defects, to increase the magnetic Curie temperature. The idea is (a) to increase the number of Group III vacancies through annealing in Group V vapor rich conditions and (b) judicious use of crystal field theory to reduce/stabilize Mn interstitials. Our experimental results constitute the highest reportedT{sub c} ({approx}130 K) in Mn doped InSb and Mn doped InP. The possibility of ferrimagnetism in Mn and Cr incorporated GaAs, was noted.

Topic Outlines in Microbiology: An Instructor's Guide for Junior and Community Colleges.

Science.gov (United States)

American Society for Microbiology, Washington, DC.

This resource guide presents subject matter organized in outline form for four topical areas: introductory microbiology; medical microbiology; microbial genetics; and microbial physiology. The first two units comprise the two most frequently taught microbiology courses in community and junior colleges. The outlines for microbial genetics and…

Students’ motivation in a disc golf-lesson and a soccer-lesson: An experimental study in the Physical Education setting

Directory of Open Access Journals (Sweden)

Kristian Vernegaard

2017-09-01

Full Text Available One of the purposes of physical education (PE in both Norway and Denmark is that PE should inspire to a lifelong active lifestyle. Based on the self-determination theory, the aim of the present study was to compare students’ intrinsic motivation, extrinsic motivation, and perceived competence in a lifestyle sport inspired PE-lesson (disc golf to a traditional PE-lesson (soccer and general PE. In addition, we aimed to investigate whether differences in motivation and perceived competence were conditional of the students’ relative attitude toward PE. The result of the study revealed that perceived competence was higher in the disc golf-lesson compared to the soccer-lesson and general PE. No overall differences in intrinsic motivation were found. However, when investigating differences in intrinsic motivation according to the students’ relative attitude toward PE, the results indicated that the students with a negative attitude toward PE was significantly more intrinsically motivated in disc golf-lesson compared to soccer-lesson and general PE. The findings may be seen as further recommendations to physical educators to vary the activity choices in physical education classes.

Effect of different factors on phase transformations in Fe-Mn alloys

International Nuclear Information System (INIS)

Balychev, Yu.M.; Tkachenko, F.K.

1983-01-01

Phase transformations proceeding under Fe-Mn alloy heating are studied and the effect of previous working conditions, particularly, cooling rate on these transformations is investigated. Investigations have been conducted on pure Fe-Mn alloys with 2-15% Mn. Phase transformations are shown to proceed according to α → #betta# and epsilon → #betta# reaction in Fe-Mn alloys containing 2-15% Mn under heating. Cooling rate in the range of approximately 5-1000 deg/min in preliminary working essentially affects phase transformations under subsequent heating

Photoluminescence of ZnS: Mn quantum dot by hydrothermal method

Directory of Open Access Journals (Sweden)

Yun Hu

2018-01-01

Full Text Available ZnS: Mn quantum dots (QDs with the average grain size from 4.2 to 7.2 nm were synthesized by a hydrothermal method. All samples were cubic zinc blende structure (β-ZnS measured using X-ray diffraction (XRD. And the main diffraction peaks of ZnS: Mn shifted slightly towards higher angle in comparison with the intrinsic ZnS because of the substitution of Mn2+ for Zn2+. Due to the small grain size (4-7 nm effect, the poor dispersion and serious reunion phenomenon for the samples were observed from transmission electron microscopy (TEM. ZnS: Mn QDs had four peaks centered at 466, 495, 522, and 554 nm, respectively, in the photoluminescence (PL spectra, in which the band at 554 nm absent in the intrinsic ZnS: Mn is attributed to the doping of Mn2+ in the lattice sites. As the concentration of Mn2+ increasing from 0% to 0.6 at%, the intensity of the PL emission also increased. But the concentration reached 0.9 at%, quenching of PL emission occurred. The peak in ZnS: Mn QDs observed at 490 cm-1 was originated from the stretching vibration of the Mn–O bonds in the Fourier transform infrared (FTIR spectra. And the small changes about this peak compared with the previous reports at 500 cm-1 can be attributed to the formation of quantum dots. This method we utilized to synthesize ZnS: Mn QDs is very simple, low cost, and applicable for other semiconductor QD materials.

Complete genome sequence of the highly Mn(II) tolerant Staphylococcus sp. AntiMn-1 isolated from deep-sea sediment in the Clarion-Clipperton Zone.

Science.gov (United States)

Wang, Xing; Lin, Danqiu; Jing, Xiaohuan; Zhu, Sidong; Yang, Jifang; Chen, Jigang

2018-01-20

Staphylococcus sp. AntiMn-1 is a deep-sea bacterium inhabiting seafloor sediment in the Clarion-Clipperton Zone (CCZ) that is highly tolerant to Mn(II) and displays efficient Mn(II) oxidation. Herein, we present the assembly and annotation of its genome. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of Ni, Fe and Mn in different proportions on microstructure and pollutant-catalyzed properties of Ni-Fe-Mn-O negative temperature coefficient ceramic nanocompositions

Energy Technology Data Exchange (ETDEWEB)

Lei, Yonglin, E-mail: leiyonglin@163.com [Engineering Research Center of Biomass Materials, Ministry of Education, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Lin, Xiaoyan, E-mail: linxy@swust.edu.cn [Engineering Research Center of Biomass Materials, Ministry of Education, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Liao, Huiwei, E-mail: liaohw@swust.edu.cn [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

2017-06-15

The effect of Ni, Fe and Mn in different proportions on microstructure and pollutant-catalyzed properties of Ni-Fe-Mn-O negative temperature coefficient ceramic nanocompositions was studied. Structural and physical characterization of all the samples was carried out by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric (TG). The results revealed that the interplanar spacing decreased with increasing Fe content, the grain size decreased with increasing Ni content, the substitution of Ni{sup 2+} in the tetrahedral sites by Fe{sup 2+} increased with increasing Fe content. And increase of iron could improve Ni-Fe-Mn-O high temperature stability. The low-temperature thermal removal efficiencies of 30 mg/L methyl orange solution for NiFeMnO{sub 4}, Ni{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4,} Ni{sub 0.6}Fe{sub 1.8}Mn{sub 0.6}O{sub 4} and Ni{sub 0.3}Fe{sub 2.1}Mn{sub 0.6}O{sub 4} systems were 83.8%, 75.2%, 78.5% and 60.3% at 2400 min, respectively. And the microwave combining with H{sub 2}O{sub 2} removal efficiencies of 30 mg/L methyl orange solution for NiFeMnO{sub 4}, Ni{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4,} Ni{sub 0.6}Fe{sub 1.8}Mn{sub 0.6}O{sub 4} and Ni{sub 0.3}Fe{sub 2.1}Mn{sub 0.6}O{sub 4} systems were 96.5%,93.8%, 98.7% and 98% at 6.0 min, respectively. These results indicated that the Ni-Fe-Mn-O ceramics with appropriate increase of iron were useful for industrial applications on degrading organic pollute. - Highlights: • The relationship of composition and catalytic properties of Ni-Fe-Mn-O was proposed. • The interplanar spacing decreased with increasing Fe content. • The grain size decreased with increasing Ni content. • The substitution of Ni{sup 2+} in the tetrahedral site by Fe{sup 2+} with increasing Fe content. �

Food Processing Curriculum Material and Resource Guide.

Science.gov (United States)

Louisiana State Dept. of Education, Baton Rouge.

Intended for secondary vocational agriculture teachers, this curriculum guide contains a course outline and a resource manual for a seven-unit food processing course on meats. Within the course outline, units are divided into separate lessons. Materials provided for each lesson include preparation for instruction (student objectives, review of…

Effects of axial coordination on immobilized Mn(salen) catalysts.

Science.gov (United States)

Teixeira, Filipe; Mosquera, Ricardo A; Melo, André; Freire, Cristina; Cordeiro, M Natália D S

2014-11-13

The consequences of anchoring Mn(salen) catalysts onto a supporting material using one of the vacant positions of the metal center are tackled by studying several Mn(salen) complexes with different axial ligands attached. This is accomplished using Density Functional Theory at the X3LYP/Triple-ζ level of theory and the Atom In Molecules formalism. The results suggest that both Mn(salen) complexes and their oxo derivatives should lie in a triplet ground state. Also, the choice of the axial ligand bears a moderate effect on the energy involved in the oxidation of the former to oxo-Mn(salen) complexes, as well as in the stability of such complexes toward ligand removal by HCl. AIM analysis further suggests that the salen ligand acts as a "charge reservoir" for the metal center, with strong correlations being obtained between the charge of salen and the electron population donated by the axial ligand to the metal center. Moreover, the results suggest that the Mn atom in Mn(salen) complexes holds different hybridization of its valence orbitals depending on the type of axial ligand present in the system.

Room temperature ferromagnetism in Mn-doped NiO nanoparticles

Science.gov (United States)

Layek, Samar; Verma, H. C.

2016-01-01

Mn-doped NiO nanoparticles of the series Ni1-xMnxO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum.

Boron-doped MnTe semiconductor-sensitized ZnO solar cells

Indian Academy of Sciences (India)

Administrator

The B-doped MnTe semiconductor was grown on ZnO using two stages of the ... nanoparticles (NPs), i.e. MnTe and MnTe2 were observed with a diameter range of approximately ..... Kongkanand A, Tvrdy K, Takechi K, Kuno M and Kamat P.

Magnetic properties of (Mn1-xRux)3Ga alloys

International Nuclear Information System (INIS)

Hori, T.; Akimitsu, M.; Miki, H.; Ohoyoama, K.; Yamaguchi, Y.

2002-01-01

We found that the pseudo binary alloys Mn 1-x Ru x 3 Ga, with 0.33≤x≤0.67, have an ordered b.c.c. structure. The lattice constant a is almost constant with respect to x: a=6.000 A for x=0.33 and a=5.992 A for x=0.67. For the alloy with x=0.33, i.e. Mn 2 RuGa, the magnetization is almost saturated in a field of 20 kOe. The saturation magnetization at 4.2 K is 23 emu/g, and the Curie temperature, T C , is 460 K. The T C of (Mn 1-x Ru x ) 3 Ga decreases almost linearly with increasing x, and it vanishes around x=0.67 (MnRu 2 Ga). We also determined atomic and magnetic structures from neutron diffraction experiments. The alloy Mn 2 RuGa (x=0.33) has an ordered structure of CuHg 2 Ti type; the magnetic Mn atoms mainly occupy the 4a (0,0,0) and 4d (3/4,3/4,3/4) sites. We also observed that the magnetic moments of Mn atoms on the 4a and 4d sites are antiparallel to each other; values of the magnetic moment are μ a =4.6 and μ d =3.3 μ B per Mn atom. (orig.)

Moessbauer and magnetic investigation of Fe-Mn alloy

International Nuclear Information System (INIS)

Yousif, A.A.

1994-01-01

Moessbauer, X-ray, magnetization and susceptibility measurements were performed to study Fe 100-x Mn x , x = 5, 15, 39, 50. The different phases of Fe-Mn were identified, and hyperfine interaction parameters and average magnetic moments of some samples were determined. The average hyperfine field and average magnetic moment decrease as x increases. The influence of the Mn neighbourhood on the derived parameters is discussed in the light of calculations using the first principle discrete variational method in the local density approximation. (orig.)

Magnetocaloric effect in In doped YbMnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sattibabu, Bhumireddi, E-mail: bsb.satti@gmail.com [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Department of Electronics and Physics, Institute of Science, GITAM University, Visakhapatnam 530045 (India); Bhatnagar, A.K., E-mail: anilb42@gmail.com [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Vinod, K.; Mani, Awadhesh [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2017-06-01

Magnetic and magnetocaloric (MCE) properties of Yb{sub 0.9}In{sub 0.1}MnO{sub 3} and Yb{sub 0.8}In{sub 0.2}MnO{sub 3} polycrystalline samples are presented in this paper. Isothermal magnetization measurements reveal a field induced magnetic transition. Magnetic entropy change of 2.34±0.35 J/mole-K for Yb{sub 0.9}In{sub 0.1}MnO{sub 3} and 2.64±0.38 J/mole-K for Yb{sub 0.8}In{sub 0.2}MnO{sub 3} field change ΔH =10 KOe is observed around the ferromagnetic ordering temperature of Yb{sup 3+}. Values of relative cooling power for the same field change are found to be 38.03±9 J /mol, and 40.90±10 J/mol for Yb{sub 0.9}In{sub 0.1}MnO{sub 3} and Yb{sub 0.8}In{sub 0.2}MnO{sub 3}, respectively. These values suggest In doped YbMnO{sub 3} may be a potential candidate for magnetic refrigerant at low temperatures.

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

Science.gov (United States)

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.

Het effect van een elektronische outline-tool op het schrijfproduct en schrijfproces

NARCIS (Netherlands)

De Smet, Milou; Brand-Gruwel, Saskia; Leijten, Mariëlle; Kirschner, Paul A.

2012-01-01

De Smet, M. J. R., Brand-Gruwel, S., Leijten, M., & Kirschner, P. A. (2012, June). Het effect van een elektronische outline-tool op het schrijfproduct en schrijfproces [The effect of an electronic outline tool on the writing product and writing process]. In R. Brouwer (Chair), Omgaan met ICT:

The Al-rich region of the Al–Fe–Mn alloy system

International Nuclear Information System (INIS)

Balanetskyy, S.; Pavlyuchkov, D.; Velikanova, T.; Grushko, B.

2015-01-01

Highlights: • Constitution of Al–Fe–Mn was studied above 50 at.% Al at 650–1070 °C. • AlMn (A2) and AlFe (B2) phases form a continuous compositional region. • Al 8 Mn 5 and Al 8 Fe 5 γ-brass type phases form a continuous compositional region. • Al 13 Fe 4 , Al 5 Fe 2 , Al 2 Fe, Al 6 Mn, Al 11 Mn 4 , γ 2 exhibit wide ternary extensions. • Four ternary intermetallics were revealed. - Abstract: Phase equilibria in the Al-rich region of the Al–Fe–Mn alloy system were studied at 1070, 1020, 950, 875, 800, 740, 695 and 650 °C. The continuous region of the bcc solid solution was estimated between the Al–Mn and Al–Fe terminals. Also the isostructural high-temperature Al–Mn and Al–Fe γ 1 -phases (γ-brass type structure) form continuous regions. The Al 6 Mn, high-temperature T-Al 11 Mn 4 and low-temperature γ 2 phases dissolve up to 9.0, 14.5 and 31.0 at.% Fe, respectively, while the M-Al 13 Fe 4 , Al 5 Fe 2 and Al 2 Fe phases dissolve up to 15.5, 11.5 and 10.0 at.% Mn, respectively. The thermodynamically stable decagonal D 3 -phase with periodicity of 1.25 nm in the specific direction and two periodic intermetallics designated φ (P6 3 /mmc; a = 0.7554, c = 0.7872 nm) and κ (P6 3 /m; a = 1.7630, c = 1.2506 nm) were identified. An additional ternary phase of unknown structure was also revealed

Learning to observe mathematical learning in lesson studies

DEFF Research Database (Denmark)

Rasmussen, Klaus; Østergaard, Camilla Hellsten; Foss, Kristian Kildemoes

2016-01-01

This poster deals with lesson study (LS) in pre-service teacher education. In particular how to prepare for, carry out, and reflect upon, observations of pupil learning. Observation is of crucial importance to the lesson study process, and here we present a study of observation features which ena...... enable or hinder fruitful lesson study. While substantial research has been carried out in the general field of bserving pupils’ learning processes and teachers’ pedagogical practice, little is known about this in the particular setting of lesson study....

Study of intergranular embrittlement in Fe-12Mn alloys

International Nuclear Information System (INIS)

Lee, H.J.

1982-06-01

A high resolution scanning Auger microscopic study has been performed on the intergranular fracture surfaces of Fe-12Mn steels in the as-austenitized condition. Fracture mode below the ductile-brittle transition temperature was intergranular whenever the alloy was quenched from the austenite field. The intergranular fracture surface failed to reveal any consistent segregation of P, S, As, O, or N. The occasional appearance of S or O on the fracture surface was found to be due to a low density precipitation of MnS and MnO 2 along the prior austenite boundaries. An AES study with Ar + ion-sputtering showed no evidence of manganese enrichment along the prior austenite boundaries, but a slight segregation of carbon which does not appear to be implicated in the tendency toward intergranular fracture. Addition of 0.002% B with a 1000 0 C/1h/WQ treatment yielded a high Charpy impact energy at liquid nitrogen temperature, preventing the intergranular fracture. High resolution AES studies showed that 3 at. % B on the prior austenite grain boundaries is most effective in increasing the grain boundary cohesive strength in an Fe-12Mn alloy. Trace additions of Mg, Zr, or V had negligible effects on the intergranular embrittlement. A 450 0 C temper of the boron-modified alloys was found to cause tempered martensite embrittlement, leading to intergranular fracture. The embrittling treatment of the Fe-12Mn alloys with and without boron additions raised the ductile-brittle transition by 150 0 C. This tempered martensite embrittlement was found to be due to the Mn enrichment of the fracture surface to 32 at. % Mn in the boron-modified alloy and 38 at. % Mn in the unmodified alloy. The Mn-enriched region along the prior austenite grain boundaries upon further tempering is believed to cause nucleation of austenite and to change the chemistry of the intergranular fracture surfaces. 61 figures

Real Estate Course Outlines--Principles, Appraisal, Finance, Law, Math, Property Management, Investments, Marketing, Brokerage.

Science.gov (United States)

Lyon, Robert

This series of course outlines was developed by the Texas Real Estate Research Center to help instructors in developing courses in compliance with the Texas Real Estate License Act Section 7(a). The outlines are general in nature and designed to serve as the basis for the development of a comprehensive course outline based on the texts and…

Collision and interaction phenomena - a historical outline

International Nuclear Information System (INIS)

Radmaneche, R.

1977-09-01

Collisions and interactions have become important for the description of matter. The author presents an outline which deals with elastic and inelastic collisions, with strong interactions, electromagnetic interactions, weak interactions and gravitational interactions. It is shown that the description of such processes has developed parallel with the understanding of matter and with the mechanism of the phenomena. Current and unsolved problems are mentioned

Characterization of Danio rerio Mn2+-dependent ADP-ribose/CDP-alcohol diphosphatase, the structural prototype of the ADPRibase-Mn-like protein family.

Directory of Open Access Journals (Sweden)

Joaquim Rui Rodrigues

Full Text Available The ADPRibase-Mn-like protein family, that belongs to the metallo-dependent phosphatase superfamily, has different functional and structural prototypes. The functional one is the Mn(2+-dependent ADP-ribose/CDP-alcohol diphosphatase from Rattus norvegicus, which is essentially inactive with Mg(2+ and active with low micromolar Mn(2+ in the hydrolysis of the phosphoanhydride linkages of ADP-ribose, CDP-alcohols and cyclic ADP-ribose (cADPR in order of decreasing efficiency. The structural prototype of the family is a Danio rerio protein with a known crystallographic structure but functionally uncharacterized. To estimate the structure-function correlation with the same protein, the activities of zebrafish ADPRibase-Mn were studied. Differences between zebrafish and rat enzymes are highlighted. The former showed a complex activity dependence on Mn(2+, significant (≈25% Mg(2+-dependent activity, but was almost inactive on cADPR (150-fold less efficient than the rat counterpart. The low cADPR hydrolase activity agreed with the zebrafish genome lacking genes coding for proteins with significant homology with cADPR-forming enzymes. Substrate-docking to zebrafish wild-type protein, and characterization of the ADPRibase-Mn H97A mutant pointed to a role of His-97 in catalysis by orientation, and to a bidentate water bridging the dinuclear metal center as the potential nucleophile. Finally, three structural elements that delimit the active site entrance in the zebrafish protein were identified as unique to the ADPRibase-Mn-like family within the metallo-dependent phosphatase superfamily.

Capacitive properties of PANI/MnO2 synthesized via simultaneous-oxidation route

International Nuclear Information System (INIS)

Zhang Jie; Shu Dong; Zhang Tianren; Chen Hongyu; Zhao Haimin; Wang Yongsheng; Sun Zhenjie; Tang Shaoqing; Fang Xueming; Cao Xiufang

2012-01-01

Highlights: ► PANI/MnO 2 composite was synthesized by the simultaneous-oxidation route. ► Good contact in inter-molecule level between PANI and MnO 2 improves the conductivity. ► The separation between PANI and MnO 2 prevents the aggregation of nano-composite. ► The maximum specific capacitance of the PANI/MnO 2 electrode is 320 F/g. ► The as-prepared PANI/MnO 2 exhibits excellent cycle stability of 84% capacitance retention after 10,000 cycles. - Abstract: Polyaniline (PANI) and manganese dioxide (MnO 2 ) composite (PANI/MnO 2 ) was synthesized via a simultaneous-oxidation route. In this route, all reactants were dispersed homogenously in precursor solution and existed as ions and molecules, and involved reactions of ions and molecules generating PANI and MnO 2 simultaneously. In this way, PANI molecule and MnO 2 molecule contact each other and arrange alternately in the composite. The inter-molecule contact improves the conductivity of the composite. The alternative arrangement of PANI molecules and MnO 2 molecules separating each other, and prevents the aggregation of PANI and cluster of MnO 2 so as to decrease the particle size of the composite. The morphology, structure, porous and capacitive properties are characterized by scanning electron microscopy, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, Branauer–Emmett–Teller test, thermogravimetric analysis, Fourier transform infrared spectroscopy, cyclic voltammetry, charge–discharge test and the electrochemical impedance measurements. The results show that MnO 2 is predominant in the PANI/MnO 2 composite and the composite exhibits larger specific surface area than pure MnO 2 . The maximum specific capacitance of the composite electrode reaches up to 320 F/g by charge–discharge test, 1.56 times higher than that of MnO 2 (125 F/g). The specific capacitance retains approximately 84% of the initial value after 10,000 cycles, indicating the good cycle stability.

Body Weight Determination from Foot Outline Length among the Iban Population in Malaysia

Directory of Open Access Journals (Sweden)

Hairunnisa Bt Mohd Anas K

2017-12-01

Full Text Available Foot impressions form a valuable physical evidence to solve crime. Foot impression measurements provide valuable information in estimating stature, weight, gender and age in crime scene investigation. In Asian countries, many people living in rural places walk without footwear. The aim of this research is to generate regression equations to determine living body weight from foot outline length among the Iban population of Malaysia. The study involved 200 (100 males, 100 females adult Ibans, mostly living in Sarawak, a state in   Malaysia. Following the standard procedure, the foot outlines were collected followed by body weight measurements and were recorded for analysis. The collected data were analysed with PASW 20 computer software. The correlation coefficient (R between the foot outline lengths and body weight was determined for males, females and pooled sample. Based on the foot outline and body weight, 30 regression equations were generated, 10 for males, 10 for females and 10 for pooled samples/unknown gender. The correlation coefficient (R values were positive and statistically significant. It is concluded that the present investigation provided regression equations to determine body weight from foot outline anthropometry. These equations can be used to determine body weight even when partial foot impressions are available at crime scenes.   Keywords: Forensic Science, Body Weight, Foot Outline, Iban Population, Malaysia

Low temperature magnetic structure of MnSe

Indian Academy of Sciences (India)

Abstract. In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour of their magnetic and transport prop- erties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures, high temperature NaCl and hexagonal NiAs. NiAs phase ...

Performance and Aging of Mn/MnO2 as an Environmentally Friendly Energetic Time Delay Composition

Science.gov (United States)

2014-04-16

16,20−22 Thermochemical predictions of this reaction were made using Cheetah v6.023 at a constant pressure of 1 atm. Figure 2 shows that the...three experiments at 40, 50, and 60 wt % Mn. Similar to Figure 2. Predicted adiabatic combustion temperature vs Mn content using Cheetah v6.0. Figure 3...Bastea, S.; Fried, L. E.; Glaesemann, K. R.; Howard, W. M.; Kuo, I.-F.; Souers, P. C. Cheetah 6.0 User Manual; Technical Report for Lawrence

Redox Reactions between Mn(II) and Hexagonal Birnessite Change Its Layer Symmetry.

Science.gov (United States)

Zhao, Huaiyan; Zhu, Mengqiang; Li, Wei; Elzinga, Evert J; Villalobos, Mario; Liu, Fan; Zhang, Jing; Feng, Xionghan; Sparks, Donald L

2016-02-16

Birnessite, a phyllomanganate and the most common type of Mn oxide, affects the fate and transport of numerous contaminants and nutrients in nature. Birnessite exhibits hexagonal (HexLayBir) or orthogonal (OrthLayBir) layer symmetry. The two types of birnessite contain contrasting content of layer vacancies and Mn(III), and accordingly have different sorption and oxidation abilities. OrthLayBir can transform to HexLayBir, but it is still vaguely understood if and how the reverse transformation occurs. Here, we show that HexLayBir (e.g., δ-MnO2 and acid birnessite) transforms to OrthLayBir after reaction with aqueous Mn(II) at low Mn(II)/Mn (in HexLayBir) molar ratios (5-24%) and pH ≥ 8. The transformation is promoted by higher pH values, as well as smaller particle size, and/or greater stacking disorder of HexLayBir. The transformation is ascribed to Mn(III) formation via the comproportionation reaction between Mn(II) adsorbed on vacant sites and the surrounding layer Mn(IV), and the subsequent migration of the Mn(III) into the vacancies with an ordered distribution in the birnessite layers. This study indicates that aqueous Mn(II) and pH are critical environmental factors controlling birnessite layer structure and reactivity in the environment.

Electrochemical performance studies of MnO2 nanoflowers recovered from spent battery

International Nuclear Information System (INIS)

Ali, Gomaa A.M.; Tan, Ling Ling; Jose, Rajan; Yusoff, Mashitah M.; Chong, Kwok Feng

2014-01-01

Highlights: • MnO 2 is recovered from spent zinc–carbon batteries as nanoflowers structure. • Recovered MnO 2 nanoflowers show high specific capacitance. • Recovered MnO 2 nanoflowers show stable electrochemical cycling up to 900 cycles. • Recovered MnO 2 nanoflowers show low resistance in EIS data. - Abstract: The electrochemical performance of MnO 2 nanoflowers recovered from spent household zinc–carbon battery is studied by cyclic voltammetry, galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy. MnO 2 nanoflowers are recovered from spent zinc–carbon battery by combination of solution leaching and electrowinning techniques. In an effort to utilize recovered MnO 2 nanoflowers as energy storage supercapacitor, it is crucial to understand their structure and electrochemical performance. X-ray diffraction analysis confirms the recovery of MnO 2 in birnessite phase, while electron microscopy analysis shows the MnO 2 is recovered as 3D nanostructure with nanoflower morphology. The recovered MnO 2 nanoflowers exhibit high specific capacitance (294 F g −1 at 10 mV s −1 ; 208.5 F g −1 at 0.1 A g −1 ) in 1 M Na 2 SO 4 electrolyte, with stable electrochemical cycling. Electrochemical data analysis reveal the great potential of MnO 2 nanoflowers recovered from spent zinc–carbon battery in the development of high performance energy storage supercapacitor system

Characterization of Mn doped ZnO nanopowder

Energy Technology Data Exchange (ETDEWEB)

Schlenker, Eva; Bakin, Andrey; Al-Suleiman, Mohamed; Wehmann, Hergo-Heinrich; Waag, Andreas [Institute of Semiconductor Technology, TU Braunschweig (Germany); Schmid, Herbert; Mader, Werner [Institute for Inorganic Chemistry, University Bonn (Germany); Bremers, Heiko; Hangleiter, Andreas [Institute of Applied Physics, TU Braunschweig (Germany)

2008-07-01

In the quest of materials for spintronic applications, diluted magnetic semiconductors recently attracted much attention. The main challenge is finding a ferromagnetic material with Curie temperature T{sub c}>300 K whose magnetic properties can be controlled electrically. The interest was particularly focused on Zn(TM)O since theoretical calculations predict that ZnO containing Mn could exhibit ferromagnetism with T{sub c} above room temperature. In the present study, the structural and magnetic properties of Mn doped ZnO nanopowder are investigated and compared to undoped ZnO crystals. Doping of ZnO with Mn results in increased lattice constants as revealed by XRD. However, an inhomogeneous distribution of the Mn dopants within the nanopowder was revealed by energy-dispersive X-ray and electron energy-loss spectroscopy. Magnetic properties are investigated by means of SQUID measurements on aggregates of powder particles as well as by MFM to study the behavior of single grains. The MFM image differs significantly from the topography as imaged by AFM and suggests the existence of long-ranging magnetic signals emerging from the sample.

Structure of MnSi on SiC(0001)

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