WorldWideScience

Sample records for grains mo

  1. Grain boundary and grain interior conduction in γ'-Bi2MoO6

    International Nuclear Information System (INIS)

    Vera, C.M.C.; Aragon, R.

    2005-01-01

    Impedance spectroscopy of fine grained ( 2 MoO 6 samples, in the frequency range of 0.1 Hz-250 kHz, relevant to sensor applications, up to 800 deg. C, has been used to characterize grain boundary and grain interior contributions to conduction. Above 500 deg. C, the grain boundary contribution is no longer rate limiting and conduction is dominated by the grain interior component. The corresponding activation energies are 0.98 eV for grain boundary and 0.73 eV for grain interior components. The weak dependence of conductivity on oxygen partial pressure below 500 deg. C can be attributed to electrode-electrolyte interface phenomena, whereas the robust response to ethanol is commensurate with changes in intrinsic ionic conductivity

  2. Grain size effect of monolayer MoS2 transistors characterized by second harmonic generation mapping

    KAUST Repository

    Lin, Chih-Pin

    2015-08-27

    We investigated different CVD-synthesized MoS2 films, aiming to correlate the device characteristics with the grain size. The grain size of MoS2 can be precisely characterized through nondestructive second harmonic generation mapping based on the degree of inversion symmetry. The devices with larger grains at the channel region show improved on/off current ratio, which can be explained by the less carrier scattering caused by the grain boundaries.

  3. Grain boundary and grain interior conduction in {gamma}'-Bi{sub 2}MoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Vera, C.M.C. [Laboratorio de Peliculas Delgadas, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina)]. E-mail: cvera@fi.uba.ar; Aragon, R. [Laboratorio de Peliculas Delgadas, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); CINSO, CONICET, CITEFA, Lasalle 4397, Villa Martelli, Buenos Aires (Argentina)

    2005-07-25

    Impedance spectroscopy of fine grained (<10 {mu}m) {gamma}'-Bi{sub 2}MoO{sub 6} samples, in the frequency range of 0.1 Hz-250 kHz, relevant to sensor applications, up to 800 deg. C, has been used to characterize grain boundary and grain interior contributions to conduction. Above 500 deg. C, the grain boundary contribution is no longer rate limiting and conduction is dominated by the grain interior component. The corresponding activation energies are 0.98 eV for grain boundary and 0.73 eV for grain interior components. The weak dependence of conductivity on oxygen partial pressure below 500 deg. C can be attributed to electrode-electrolyte interface phenomena, whereas the robust response to ethanol is commensurate with changes in intrinsic ionic conductivity.

  4. Refinement of grain structure in 20 MnNiMo (SA508C) steel

    International Nuclear Information System (INIS)

    Sheng Zhongqi; Xiao Hong; Peng Feng; Zou Min

    1997-04-01

    The size of prior austenite grains and bainitic colonies of 20 MnNiMo (SA508C) steel (a reactor pressure vessel steel) after normal heat treatment is measured and its controlling factors are discussed. Results show that low aluminium content can induce serious mixed structure with fine and coarse grains in prior austenite. Fast cooling rate can promote refinement of bainitic colonies. Further refinement of grains can be obtained by inter-critical quenching. (5 figs., 1 tab.)

  5. Multiaxial creep of fine grained 0.5Cr-0.5Mo-0.25V and coarse grained 1Cr-0.5Mo steels

    International Nuclear Information System (INIS)

    Browne, R.J.; Flewitt, P.E.J.; Lonsdale, D.

    1991-01-01

    To explore the multiaxial creep response of materials used for electrical power generating plant, two steels, a fine grained 0.5Cr-0.5Mo-0.25V steel in a normalised and tempered condition with high creep ductility and a coarse grained 1Cr-0.5Mo steel in a quenched and tempered condition with low uniaxial creep ductility, have been selected. A range of multiaxial stress testing techniques which span the stress states that would allow identification of any technique dependent variables has been used. The deformation and failure of the normalised and tempered 0.5Cr-0.5Mo-0.25V steel for a range of multiaxial test techniques and, therefore, stress states may be described by an equivalent stress criterion. The results from the multiaxial tests carried out on the fully bainitic 1Cr-0.5Mo steel show that the multiaxial stress rupture criterion (MSRC) varies with stress state; at high triaxiality (notch), it is controlled by the maximum principal stress, whereas at low triaxiality (shear) it is dependent on both maximum principal stress and equivalent stress. Furthermore, a simple description of stress state based on maximum principal and equivalent stress does not define this uniquely, since the MSRC derived from uniaxial and torsion testing does not describe the failure of notch, tube, or double shear tests. (author)

  6. Grain boundary engineering to control the discontinuous precipitation in multicomponent U10Mo alloy

    Energy Technology Data Exchange (ETDEWEB)

    Devaraj, Arun; Kovarik, Libor; Kautz, Elizabeth; Arey, Bruce; Jana, Saumyadeep; Lavender, Curt; Joshi, Vineet

    2018-06-01

    Grain boundaries in metallic alloys often play a crucial role, not only in determining the mechanical properties or thermal stability of alloys, but also in dictating the phase transformation kinetics during thermomechanical processing. We demonstrate that locally stabilized structure and compositional segregation at grain boundaries—“grain boundary complexions”—in a complex multicomponent alloy can be modified to influence the kinetics of cellular transformation during subsequent thermomechanical processing. Using aberration-corrected scanning transmission electron microscopy and atom probe tomography analysis of a metallic nuclear fuel highly relevant to worldwide nuclear non-proliferation efforts —uranium-10 wt% molybdenum (U-10Mo) alloy, new evidence for the existence of grain boundary complexion is provided. We then modified the concentration of impurities dissolved in Υ-UMo grain interiors and/or segregated to Υ-UMo grain boundaries by changing the homogenization treatment, and these effects were used used to retard the kinetics of cellular transformation during subsequent sub-eutectoid annealing in this U-10-Mo alloy during sub-eutectoid annealing. Thus, this work provided insights on tailoring the final microstructure of the U-10Mo alloy, which can potentially improve the irradiation performance of this important class of alloy fuels.

  7. Effect of Grain Misorientation Angle on Twinning Propagation in Ti-15Mo Alloy

    Science.gov (United States)

    Im, Y.-D.; Lee, Y.-K.; Song, K. H.

    2018-03-01

    This study was carried out to evaluate the effect of grain misorientation angle distribution on the deformation behavior and twinning of Ti-15Mo alloy. Cold rolling exhibited a significant texture with grains oriented along the {111}//normal direction, which correlate with a higher fraction of low-angle boundaries. This material showed a lower yield strength and higher elongation than those of the hot rolled material. The twinning propagation mainly occurred between neighboring grains with a low-angle relation. Consequently, the texture development was correlated with low-angle boundaries and affected by the increase in the twinning density, which increased the strain hardening rate.

  8. Trace, isotopic analysis of micron-sized grains -- Mo, Zr analysis of stardust (SiC and graphite grains).

    Energy Technology Data Exchange (ETDEWEB)

    Pellin, M. J.; Nicolussi, G. K.

    1998-02-19

    Secondary Neutral Mass Spectrometry using resonant laser ionization can provide for both high useful yields and high discrimination while maintaining high lateral and depth resolutions. An example of the power of the method is measurement of the isotopic composition of Mo and Zr in 1-5 {micro}m presolar SiC and graphite grains isolated from the Murchison CM2 meteorite for the first time. These grains have survived the formation of the Solar System and isotopic analysis reveals a record of the stellar nucleosynthesis present during their formation. Mo and Zr, though present at less than 10 ppm in some grains, are particularly useful in that among their isotopes are members that can only be formed by distinct nucleosynthetic processes known as s-, p-, and r-process. Successful isotopic analysis of these elements requires both high selectivity (since these are trace elements) and high efficiency (since the total number of atoms available are limited). Resonant Ionization Spectroscopy is particularly useful and flexible in this application. While the sensitivity of this t.edmique has often been reported in the past, we focus hereon the very low noise properties of the technique. We further demonstrate the efficacy of noise removal by two complimentary methods. First we use the resonant nature of the signal to subtract background signal. Second we demonstrate that by choosing the appropriate resonance scheme background can often be dramatically reduced.

  9. Superhard Mo-Al-Ni films composed of grains with different crystallographic orientations and/or lattice structures

    Czech Academy of Sciences Publication Activity Database

    Musil, Jindřich; Stadnik, T.; Čerňanský, Marian

    2003-01-01

    Roč. 36, č. 1 (2003), s. 22-26 ISSN 1225-8024 R&D Projects: GA MŠk ME 529 Institutional research plan: CEZ:AV0Z1010914; CEZ:MSM 235200002 Keywords : Mo-Al-N film * hardness * structure * grain size * mixture of grains Subject RIV: BM - Solid Matter Physics ; Magnetism

  10. Intergranular fracture stress and phosphorus grain boundary segregation of a Mn-Ni-Mo steel

    International Nuclear Information System (INIS)

    Naudin, C.; Frund, J.M.; Pineau, A.

    1999-01-01

    Nuclear Reactor Pressure Vessel (RPV) steel A508 class 3 which is a low alloyed steel is not usually sensitive to reversible temper embrittlement when properly heat treated. However heterogeneous zones may be present in particular near the inner side of the vessel. These zones result from the segregation of the alloying elements (C, Mn, Ni, Mo) and impurities (S, P) taking place during solidification of the material. They are called segregated zones (or ghost lines). They can reach 2 mm thick along the radius and 30 mm long through the circumferential direction. Their susceptibility to reversible temper embrittlement is mainly due to grain boundary phosphorus segregation triggering brittle intergranular fracture when the material is tested at low temperature. In this material like in other steels the influence of some other alloying elements (Mo, Mn...) is clearly significant and should also be taken into account. But phosphorus effect has proved to be predominant. The aim of the present study is therefore to find out a quantitative relationship between grain boundary phosphorus segregation and critical intergranular fracture stress. A synthetic steel with a chemical composition representative of an average segregated zone was prepared for the present study. A number of heat treatments were applied to reach different embrittlement conditions. Then brittle fracture properties were obtained by performing cryogenic fracture tests on notched tensile specimens while the corresponding grain boundary phosphorus levels were measured by Auger electron spectroscopy. Systematic fractographic observations were carried out. Moreover an attempt to determine the influence of temperature on the critical intergranular fracture stress was made

  11. Intergranular fracture stress and phosphorus grain boundary segregation of a Mn-Ni-Mo steel

    Energy Technology Data Exchange (ETDEWEB)

    Naudin, C.; Frund, J.M. [EDF, Moret sur Loing (France). Direction des Etudes et Recherches; Pineau, A. [Ecole des Mines de Paris, Evry (France). Centre des Materiaux

    1999-04-09

    Nuclear Reactor Pressure Vessel (RPV) steel A508 class 3 which is a low alloyed steel is not usually sensitive to reversible temper embrittlement when properly heat treated. However heterogeneous zones may be present in particular near the inner side of the vessel. These zones result from the segregation of the alloying elements (C, Mn, Ni, Mo) and impurities (S, P) taking place during solidification of the material. They are called segregated zones (or ghost lines). They can reach 2 mm thick along the radius and 30 mm long through the circumferential direction. Their susceptibility to reversible temper embrittlement is mainly due to grain boundary phosphorus segregation triggering brittle intergranular fracture when the material is tested at low temperature. In this material like in other steels the influence of some other alloying elements (Mo, Mn...) is clearly significant and should also be taken into account. But phosphorus effect has proved to be predominant. The aim of the present study is therefore to find out a quantitative relationship between grain boundary phosphorus segregation and critical intergranular fracture stress. A synthetic steel with a chemical composition representative of an average segregated zone was prepared for the present study. A number of heat treatments were applied to reach different embrittlement conditions. Then brittle fracture properties were obtained by performing cryogenic fracture tests on notched tensile specimens while the corresponding grain boundary phosphorus levels were measured by Auger electron spectroscopy. Systematic fractographic observations were carried out. Moreover an attempt to determine the influence of temperature on the critical intergranular fracture stress was made.

  12. Record Low Thermal Conductivity of Polycrystalline MoS2 Films: Tuning the Thermal Conductivity by Grain Orientation.

    Science.gov (United States)

    Sledzinska, Marianna; Quey, Romain; Mortazavi, Bohayra; Graczykowski, Bartlomiej; Placidi, Marcel; Saleta Reig, David; Navarro-Urrios, Daniel; Alzina, Francesc; Colombo, Luciano; Roche, Stephan; Sotomayor Torres, Clivia M

    2017-11-01

    We report a record low thermal conductivity in polycrystalline MoS 2 obtained for ultrathin films with varying grain sizes and orientations. By optimizing the sulfurization parameters of nanometer-thick Mo layers, five MoS 2 films containing a combination of horizontally and vertically oriented grains, with respect to the bulk (001) monocrystal, were grown. From transmission electron microscopy, the average grain size, typically below 10 nm, and proportion of differently oriented grains were extracted. The thermal conductivity of the suspended samples was extracted from a Raman laser-power-dependent study, and the lowest value of thermal conductivity of 0.27 W m -1 K -1 , which reaches a similar value as that of Teflon, is obtained in a polycrystalline sample formed by a combination of horizontally and vertically oriented grains in similar proportion. Analysis by means of molecular dynamics and finite element method simulations confirm that such a grain arrangement leads to lower grain boundary conductance. We discuss the possible use of these thermal insulating films in the context of electronics and thermoelectricity.

  13. Solute grain boundary segregation during high temperature plastic deformation in a Cr-Mo low alloy steel

    International Nuclear Information System (INIS)

    Chen, X.-M.; Song, S.-H.; Weng, L.-Q.; Liu, S.-J.

    2011-01-01

    Highlights: → The segregation of P and Mo is evidently enhanced by plastic deformation. → The boundary concentrations of P and Mo increase with increasing strain. → A model with consideration of site competition in grain boundary segregation in a ternary system is developed. → Model predictions show a reasonable agreement with the observations. - Abstract: Grain boundary segregation of Cr, Mo and P to austenite grain boundaries in a P-doped 1Cr0.5Mo steel is examined using field emission gun scanning transmission electron microscopy for the specimens undeformed and deformed by 10% with a strain rate of 2 x 10 -3 s -1 at 900 deg. C, and subsequently water quenched to room temperature. Before deformation, there is some segregation for Mo and P, but the segregation is considerably increased after deformation. The segregation of Cr is very small and there is no apparent difference between the undeformed and deformed specimens. Since the thermal equilibrium segregation has been attained prior to deformation, the segregation produced during deformation has a non-equilibrium characteristic. A theoretical model with consideration of site competition in grain boundary segregation between two solutes in a ternary alloy is developed to explain the experimental results. Model predictions are made, which show a reasonable agreement with the observations.

  14. Microstructure of as atomized and annealed U-Mo7 particles: A SEM/EBSD study of grain growth

    Science.gov (United States)

    Iltis, X.; Zacharie-Aubrun, I.; Ryu, H. J.; Park, J. M.; Leenaers, A.; Yacout, A. M.; Keiser, D. D.; Vanni, F.; Stepnik, B.; Blay, T.; Tarisien, N.; Tanguy, C.; Palancher, H.

    2017-11-01

    Significant progresses in the performances under in-pile irradiation of particular U-Mo based fuels have been observed over the last fifteen years. One of the remaining issues has still to be tackled for use as a LEU fuel in the high power research reactors: the U-Mo recrystallization and its associated swelling have to be controlled or delayed. One way to mitigate this problem would be to optimize the initial microstructure of U-Mo atomized particle, by homogenizing Mo concentration and increasing grain size. This paper mainly focuses on U-Mo grain growth. Based on samples prepared in the framework of KOMO-5 and EMPIrE tests, a methodological work based on the use of EBSD is presented. In particular, surface preparation procedures are proposed for powders and rods, this last one being most likely readily applicable for plate analysis. As-atomized microstructures are analyzed in detail and subsequently compared to those obtained on particles annealed at 1000 °C under various conditions. It is found that 1 h annealing under vacuum is a good compromise of temperature and time to meet the development goals, provided that few impurity precipitates are present within U-Mo particles, since these can impact grain growth.

  15. Effect of Grain Boundary Character Distribution on the Impact Toughness of 410NiMo Weld Metal

    DEFF Research Database (Denmark)

    Divya, M.; Das, Chitta Ranjan; Chowdhury, Sandip Ghosh

    2016-01-01

    Grain boundary character distributions in 410NiMo weld metal were studied in the as-welded, first-stage, and second-stage postweld heat treatment (PWHT) conditions, and these were correlated with the Charpy-V impact toughness values of the material. The high impact toughness values in the weld...

  16. Ultrasonic attenuation as a function of heat treatment and grain size in 79Ni--6Mo--15Fe alloy

    International Nuclear Information System (INIS)

    Gieske, J.H.

    1978-03-01

    A pulse echo ultrasonic technique was used to measure the attenuation coefficient for 79Ni-6Mo-15Fe alloy specimens. The attenuation coefficient was determined using a 25 MHz ultrasonic transducer for specimens which had undergone different time-temperature heat treatments. The ultrasonic attenuation data versus heat treat time was used to assess grain size growth in the specimens

  17. Structure and properties of ultrafine-grained MoSi2 + Si3N4 composites synthesized by mechanical alloying

    International Nuclear Information System (INIS)

    Suryanarayana, C.

    2008-01-01

    Monolithic MoSi 2 and MoSi 2 + Si 3 N 4 ultrafine-grained composites with 2.5 or 5.0 wt.% Si 3 N 4 were synthesized by mechanical alloying. The microstructure and crystal structure of the phases present in the as-milled powders were determined by electron microscopy and X-ray diffraction methods. The mechanically alloyed powders were successfully consolidated to full density by vacuum hot pressing. A detailed microstructural investigation and mechanical properties (hardness and fracture toughness) evaluation of the consolidated products was presented. After consolidation, the microstructure continued to be fine-grained (in the submicron range), but no appreciable increase in the room temperature fracture toughness of MoSi 2 was observed for the composites by the addition of Si 3 N 4

  18. Image analysis measurements of prior austenitic grain size of 9Cr-1Mo martensitic steels in function of the austenitization conditions. Quantification par analyse d'images de la taille de l'ancien grain austenitique d'aciers martensitiques 9Cr-1Mo

    Energy Technology Data Exchange (ETDEWEB)

    Barcelo, F.; Brachet, J.C. (CEA Centre d' Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Technologie des Materiaux)

    1994-02-01

    The size grain of the high temperature phase (austenite) can influence mechanical properties as well as some physical properties of 9Cr-1Mo martensitic steels. Automated image analysis makes it possible to quantify the size of an austenitic grain with respect to the heat treatment conditions of austenitization (time-temperature). The results obtained on a 9Cr-1Mo steel have made it possible to describe the growth kinetics of the austenitic grain of this steel. (authors). 21 refs., 14 figs.

  19. Point Defects and Grain Boundaries in Rotationally Commensurate MoS 2 on Epitaxial Graphene

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaolong [Applied Physics Graduate Program, ‡Department of Materials; Balla, Itamar [Applied Physics Graduate Program, ‡Department of Materials; Bergeron, Hadallia [Applied Physics Graduate Program, ‡Department of Materials; Hersam, Mark C. [Applied Physics Graduate Program, ‡Department of Materials

    2016-03-28

    With reduced degrees of freedom, structural defects are expected to play a greater role in two-dimensional materials in comparison to their bulk counterparts. In particular, mechanical strength, electronic properties, and chemical reactivity are strongly affected by crystal imperfections in the atomically thin limit. Here, ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) are employed to interrogate point and line defects in monolayer MoS2 grown on epitaxial graphene (EG) at the atomic scale. Five types of point defects are observed with the majority species showing apparent structures that are consistent with vacancy and interstitial models. The total defect density is observed to be lower than MoS2 grown on other substrates and is likely attributed to the van der Waals epitaxy of MoS2 on EG. Grain boundaries (GBs) with 30° and 60° tilt angles resulting from the rotational commensurability of MoS2 on EG are more easily resolved by STM than atomic force microscopy at similar scales due to the enhanced contrast from their distinct electronic states. For example, band gap reduction to ~0.8 and ~0.5 eV is observed with STS for 30° and 60° GBs, respectively. In addition, atomic resolution STM images of these GBs are found to agree well with proposed structure models. This work offers quantitative insight into the structure and properties of common defects in MoS2 and suggests pathways for tailoring the performance of MoS2/graphene heterostructures via defect engineering.

  20. Effect of Composition and Deformation on Coarse-Grained Austenite Transformation in Nb-Mo Microalloyed Steels

    Science.gov (United States)

    Isasti, N.; Jorge-Badiola, D.; Taheri, M. L.; López, B.; Uranga, P.

    2011-12-01

    Thermomechanical processing of microalloyed steels containing niobium can be performed to obtain deformed austenite prior to transformation. Accelerated cooling can be employed to refine the final microstructure and, consequently, to improve both strength and toughness. This general rule is fulfilled if the transformation occurs on a quite homogeneous austenite microstructure. Nevertheless, the presence of coarse austenite grains before transformation in different industrial processes is a usual source of concern, and regarding toughness, the coarsest high-angle boundary units would determine its final value. Sets of deformation dilatometry tests were carried out using three 0.06 pct Nb microalloyed steels to evaluate the effect of Mo alloying additions (0, 0.16, and 0.31 pct Mo) on final transformation from both recrystallized and unrecrystallized coarse-grained austenite. Continuous cooling transformation (CCT) diagrams were created, and detailed microstructural characterization was achieved through the use of optical microscopy (OM), field emission gun scanning electron microscopy (FEGSEM), and electron backscattered diffraction (EBSD). The resultant microstructures ranged from polygonal ferrite (PF) and pearlite (P) at slow cooling ranges to bainitic ferrite (BF) accompanied by martensite (M) for fast cooling rates. Plastic deformation of the parent austenite accelerated both ferrite and bainite transformation, moving the CCT curves to higher temperatures and shorter times. However, an increase in the final heterogeneity was observed when BF packets were formed, creating coarse high-angle grain boundary units.

  1. Autonomous filling of grain-boundary cavities during creep loading in Fe-Mo alloys

    NARCIS (Netherlands)

    Zhang, S.; Fang, H.; Gramsma, M. E.; Kwakernaak, C.; Sloof, W.G.; Tichelaar, F.D.; Kuzmina, M; Herbig, M; Raabe, D.; Brück, E.H.; van der Zwaag, S.; van Dijk, N.H.

    2016-01-01

    We have investigated the autonomous repair of creep damage by site-selective precipitation in a binary Fe-Mo alloy (6.2 wt pct Mo) during constant-stress creep tests at temperatures of 813 K, 823 K, and 838 K (540 °C, 550 °C, and 565 °C). Scanning electron microscopy studies on the morphology of

  2. Stress-induced non-equilibrium grain boundary segregation of phosphorus in a Cr-Mo low alloy steel

    International Nuclear Information System (INIS)

    Song, S.-H.; Wu, J.; Wang, D.-Y.; Weng, L.-Q.; Zheng, L.

    2006-01-01

    Grain boundary segregation of phosphorus under a 40 MPa tensile stress at 520 deg. C in a 0.025 wt.% P-doped 2.25Cr1Mo steel, which has already been thermally equilibrated, is examined using Auger electron spectroscopy. The segregation of phosphorus during stress-ageing has a non-equilibrium characteristic, i.e. it is non-equilibrium segregation. The segregation level first increases with increasing stress-ageing time until about 0.5 h and then diminishes with further increasing stress-ageing time, leading the boundary concentration of phosphorus to return to its thermal equilibrium value after ageing for about 15 h. Therefore, the critical time for this non-equilibrium grain boundary segregation of phosphorus is about 0.5 h at which the segregation is peaked. At this critical time, the boundary concentration of phosphorus is about 20.5 at.%, which is about 4.5 at.% higher than its thermal equilibrium level. Xu's kinetic model for stress-induced grain boundary segregation [T.D. Xu, Philos. Mag. 83 (2003) 889-899; T.D. Xu, B.-Y. Cheng, Prog. Mater. Sci. 49 (2) (2004) 109-208] is used to analyse the experimental results, demonstrating that the measured data may be well simulated by the model

  3. Quantification by image analysis of grain size of the high temperature phase (austenite) of martensitic steels 9Cr-1Mo. Quantification par analyse d'images de la taille de grain de la phase haute temperature (austenite) d'aciers martensitiques 9Cr-1Mo

    Energy Technology Data Exchange (ETDEWEB)

    Barcelo, F.; Brachet, J.C. (CEA Centre d' Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Technologie des Materiaux)

    1993-09-01

    In martensitic steels, the austenitic grain size before transformation may influence mechanical properties. 9Cr-1Mo steel (EM10) is used in hexagonal pipes fabrication in fast neutrons reactors. Image analysis allows to quantify the older grain size in function of the austenization heat treatment conditions. (A.B.). 2 figs.

  4. Phosphorus grain boundary segregation under an intermediate applied tensile stress in a Cr-Mo low alloy steel

    International Nuclear Information System (INIS)

    Song, S.-H.; Wu, J.; Weng, L.-Q.; Xi, T.-H.

    2009-01-01

    Phosphorus grain boundary segregation under an intermediate applied tensile stress of 200 MPa at 520 deg. C in a 0.025 wt.% P-doped 2.25Cr1Mo steel, which has already been thermally equilibrated, is observed using Auger electron spectroscopy. The segregation during stress ageing has a non-equilibrium nature. There are two phosphorus segregation peaks over its thermal equilibrium level, and between them there is a depletion trough of phosphorus below its thermal equilibrium level. The first segregation peak is mainly caused by the vacancy-phosphorus complex effect and the second one by the diffusional creep effect. The depletion trough of phosphorus at the initial creep stage may be attributed to the strain hardening bias effect.

  5. Dependence of ductile-to-brittle transition temperature on phosphorus grain boundary segregation for a 2.25Cr1Mo steel

    International Nuclear Information System (INIS)

    Song, S.-H.; Zhuang, H.; Wu, J.; Weng, L.-Q.; Yuan, Z.-X.; Xi, T.-H.

    2008-01-01

    Equilibrium grain boundary segregation of phosphorus in a 2.25Cr1Mo steel was studied by means of Auger electron spectroscopy (AES). After quenching from 980 deg. C and tempering at 650 deg. C, the steel samples were aged for different periods of time at 560, 520 and 480 deg. C, respectively, followed by AES measurements. Based on the experimental values of the equilibrium segregation levels at different temperatures along with equilibrium segregation theories, the thermodynamic parameters of segregation were evaluated. With the use of Charpy impact testing along with the AES results on phosphorus grain boundary concentration, a relationship between ductile-to-brittle transition temperature (DBTT) and phosphorus boundary concentration was established. On the basis of this relationship, predictions of the DBTT were made through predicting the grain boundary segregation of phosphorus

  6. Effect of zone-refining on orientations of recrystallized grains formed in rolled and annealed pure Mo and Ta single crystals

    International Nuclear Information System (INIS)

    Ohba, Y.; Fujii, T.

    1977-01-01

    The effects of the number of zone passes on the orientations of recrystallized grains are studied in rolled and annealed Mo and Ta crystals with a (111)[1 - 1 - 2] orientation. The recrystallized texture of Mo which has been zone-refined only once is mainly composed of (511)[1 - 05] and (310)[001] components, whereas that of Mo which has been zone-refined three times is composed of a sharp single (110)[001] component. In Ta which has been zone-refined once, the recrystallized texture is composed of (110)[001] and (1 - 1 - 5)[5 - 5 - 2 - ] components, the latter having a twin relationship with the rolled matrix. In Ta which has been zone-refined three times, the (110)[001] component is still predominant but the (110)[001] component decreases and the (1 - 1 - 5)[5 - 5 - 2 - ] component increases with increasing number of zone passes. Most of the recrystallized grains are in good coincidence with the rolled matrix. (Auth.)

  7. Non-equilibrium grain boundary segregation of phosphorus under a high applied tensile stress in a 2.25Cr1Mo steel

    International Nuclear Information System (INIS)

    Song, S.-H.; Wu, J.; Yuan, Z.-X.; Weng, L.-Q.; Xi, T.-H.

    2008-01-01

    Grain boundary segregation of phosphorus under a 350 MPa tensile stress at 520 deg. C in a 0.025 wt.% P-doped 2.25Cr1Mo steel, which has already been thermally equilibrated, is examined using Auger electron spectroscopy. The segregation of phosphorus during stress ageing has a non-equilibrium characteristic, which has two phosphorus segregation peaks over its equilibrium segregation level, one of which is mainly due to the vacancy-phosphorus complex effect and the other due to the diffusional creep effect

  8. An Auger electron spectroscopy study of phosphorus and molybdenum grain boundary segregation in a 2.25Cr1Mo steel

    International Nuclear Information System (INIS)

    Wu, J.; Song, S.-H.; Weng, L.-Q.; Xi, T.-H.; Yuan, Z.-X.

    2008-01-01

    Thermodynamics of grain boundary segregation of phosphorus and molybdenum in a 2.25Cr1Mo steel were investigated using Auger electron spectroscopy (AES). After quenching from 980 deg. C and tempering at 650 deg. C, the steel samples were aged for different times at 560 deg. C, 520 deg. C and 480 deg. C, respectively, followed by AES measurements. Based on the AES results for equilibrium grain boundary concentrations of phosphorus and molybdenum, it is seen that the interaction between these two elements in segregation is weak and the free energies of segregation are constant, being about 38 kJ/mol and 17 kJ/mol for phosphorus and molybdenum, respectively

  9. Doping induced grain size reduction and photocatalytic performance enhancement of SrMoO{sub 4}:Bi{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yunjian, E-mail: wangyunjianmail@163.com; Xu, Hui; Shao, Congying; Cao, Jing, E-mail: caojing@mail.ipc.ac.cn

    2017-01-15

    Graphical abstract: Photocatalytic performance of SrMoO{sub 4} was greatly improved by Bi{sup 3+} doping effects, including crystalline size reduction, band gap narrowing, and lattice contraction. - Highlights: • An efficient SrMoO{sub 4} photocatalyst was fabricated by Bi{sup 3+} doping under hydrothermal condition. • Bi{sup 3+} doping effects, including crystalline size reduction, band gap narrowing, and lattice contraction were discovered in SrMoO{sub 4} nanomaterials. • The photocatalytic activity was great improved on account of Bi{sup 3+} doping effects. • Photoluminescence studies found that hydroxyl radical (·OH) is the main active species in the photocatalytic degradation process. - Abstract: Ion doping is one of the most effective ways to develop photocatalysts by creating impurity levels in the energy band structure. In this paper, novel Bi{sup 3+} doped SrMoO{sub 4} (SrMoO{sub 4}:Bi{sup 3+}) nanocrystals were prepared by a simple hydrothermal method. By systematic characterizations using x-ray diffraction, infrared spectra, UV–vis spectra, X-ray photoelectron spectroscopy and transmission electron microscopy, it is demonstrated that all the samples crystallized in a single phase of scheelite structure, and particle sizes of SrMoO{sub 4}:Bi{sup 3+} gradually decreased. The Bi{sup 3+} doped nanoparticles showed lattice contraction, and band-gap narrowing. The photocatalytic activity of the samples was measured by monitoring the degradation of methylene blue dye in an aqueous solution under UV-radiation exposure. It is found that SrMoO{sub 4}:Bi{sup 3+} showed excellent activity toward photodegradation of methylene blue solution under UV light irradiation compared to the pure SrMoO{sub 4}. These observations are interpreted in terms of the Bi{sup 3+} doping effects and the increased the surface active sites, which results in the improved the ratio of surface charge carrier transfer rate and reduced the electron–hole recombination rate. These

  10. Observation of Wigner crystal phase and ripplon-limited mobility behavior in monolayer CVD MoS2 with grain boundary

    KAUST Repository

    Chen, Jyun-Hong

    2018-03-12

    Two-dimensional electron gas (2DEG) is crucial in condensed matter physics and is present on the surface of liquid helium and at the interface of semiconductors. Monolayer MoS2 of 2D materials also contains 2DEG in an atomic layer as field effect transistor (FET) ultrathin channel. In this study, we synthesized double triangular MoS2 through a chemical vapor deposition method to obtain grain boundaries for forming a ripple structure in FET channel. When the temperature was higher than approximately 175 K, the temperature dependence of the electron mobility μ was consistent with those in previous experiments and theoretical predictions. When the temperature was lower than approximately 175 K, the mobility behavior decreased with the temperature; this finding was also consistent with that of the previous experiments. We are the first research group to explain the decreasing mobility behavior by using the Wigner crystal phase and to discover the temperature independence of ripplon-limited mobility behavior at lower temperatures. Although these mobility behaviors have been studied on the surface of liquid helium through theories and experiments, they have not previously analyzed in 2D materials and semiconductors. We are the first research group to report the similar temperature-dependent mobility behavior of the surface of liquid helium and the monolayer MoS2.

  11. Effect of prior-austenite grain refinement on microstructure, mechanical properties and thermal embrittlement of 9Cr-1Mo-0.1C steel

    Science.gov (United States)

    Karthikeyan, T.; Dash, Manmath Kumar; Ravikirana; Mythili, R.; Panneer Selvi, S.; Moitra, A.; Saroja, S.

    2017-10-01

    The effect of 'conventional normalizing and tempering' (CNT) and 'double austenitization based normalizing and tempering' (DNT) heat treatments on the microstructure, tensile, creep and impact toughness properties of 9Cr-1Mo steel has been studied. The tempered martensite microstructure obtained through DNT treatment exhibited smaller sizes of prior-austenite grains/martensite packets (28 μm/11 μm) compared to the CNT treatment (44 μm/14 μm). The tempered martensite morphology was largely retained after long-term thermal aging at 550 °C/5000 h, while the M23C6 and M2(C,N) type of precipitates were found to act as nucleation sites for precipitation of brittle Fe2Mo Laves phase. The grain refinement by DNT was found to be beneficial for minimizing the ductile-to-brittle transition characteristics (25 °C lower ductile-to-brittle transition temperature and 70 J higher upper shelf energy) over the CNT. Thermal embrittlement occurred in both heated treated steels, but the transition temperature of aged DNT steel remained below room temperature. Fractured Charpy specimens revealed ductile failure by void coalescence for high temperature tests, and a quasi-cleavage fracture at low temperatures with few isolated occurrence of intergranular crack in thermal embrittled steel. The DNT treated steel resulted in similar or better tensile and creep properties, when compared to the CNT treatment. The homogeneous fine grained tempered martensite microstructure obtained by DNT treatment resulted in improved embrittlement resistance and mechanical properties over the conventional treatment.

  12. Microstructure and Impact Toughness of the Intercritically Reheated Coarse-grained Heat Affected Zone of 13MnNiMoR Steel

    Science.gov (United States)

    Han, Yang; Jinbo, Qu

    The microstructure and impact toughness of intercritically reheated coarse-grained heat affected zone (ICCGHAZ) of 13MnNiMoR and the effect of post-welding heat treatment (PWHT) process were investigated by means of welding thermal simulation test. The result shows that after the first welding thermal cycle, the microstructure of the coarse-grained heat affected zone (CGHAZ) mainly consists of granular bainite and lath bainite, with good impact toughness. After the second thermal cycle with a peak temperature of 650 to 700°C, the CGHAZ microstructure experiences a tempering process and its impact toughness improves due to the precipitation of carbides and reduction of dislocations. With a second peak temperature of 750 to 850°C, part of the CGHAZ microstructure retransforms to austenite and during cooling, martensite-austenite (MA) constituents forms along grain boundaries in the ICCGHAZ microstructure, leading to a sharp drop of toughness. When the second thermal cycle peak temperature is up to 900°C, the CGHAZ microstructure is fully austenitized, and the final microstructure mainly consists of ferrite and granular bainite. After a PWHT process in the temperature range of 560 to 640°C, the impact toughness of ICCGHAZ is markedly improved, primarily due to the decomposition of MA constituents.

  13. Investigations on grain boundary segregation energy of phosphorus in 12Cr1MoV steel under elastic stress

    Czech Academy of Sciences Publication Activity Database

    Zheng, L.; Fu, Y.; Lejček, Pavel; Song, S.; Schmitz, G.; Meng, Y.

    2016-01-01

    Roč. 18, č. 4 (2016), 506-510 ISSN 1438-1656 R&D Projects: GA ČR GAP108/12/0144 Institutional support: RVO:68378271 Keywords : grain boundary segregation, * stress effect, * phosphorus, * steel Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.319, year: 2016

  14. Effect of solute grain boundary segregation and hardness on the ductile-to-brittle transition for a Cr-Mo low-alloy steel

    International Nuclear Information System (INIS)

    Shen, D.-D.; Song, S.-H.; Yuan, Z.-X.; Weng, L.-Q.

    2005-01-01

    Combined solute grain boundary segregation and hardness effect on the ductile-to-brittle transition is examined for a P-doped 2.25Cr-1Mo steel by means of Auger electron spectroscopy (AES) in conjunction with hardness measurements, Charpy impact tests and scanning electron microscopy (SEM). During ageing at 540 deg. C after water quenching from 980 deg. C, the segregation of phosphorus, molybdenum and chromium increases and the hardness decreases with increasing ageing time. The ductile-to-brittle transition temperature (DBTT) increases with increasing phosphorus segregation and decreases with decreasing hardness. The phosphorus segregation effect is dominant until 100 h ageing and after that the hardness effect becomes dominant, making the DBTT decrease with further increasing ageing time although the segregation of phosphorus still increases strongly. The segregation of molybdenum has some effect on the DBTT decrease

  15. About oxide dispersion particles chemical compatibility with areas coherent dissipation/sub-grains of bcc-alloys in Fe - (Cr, V, Mo, W systems

    Directory of Open Access Journals (Sweden)

    Udovsky A.

    2016-01-01

    Full Text Available A concept of partial magnetic moments (PMM of the iron atoms located in the first ч four coordination spheres (1÷4 CS for bcc lattice have been introduced based on analysis of results obtained by quantum-mechanical calculations (QMC for volume dependence of the average magnetic moment ferromagnetic (FM Fe. The values of these moments have been calculated for pure bcc Fe and bcc - Fe-Cr alloys. This concept has been used to formulate a three sub-lattice model for binary FM alloys of the Fe-M systems (M is an alloying paramagnetic element. Physical reason for sign change dependence of the short-range order and mixing enthalpy obtained by QMCs for Fe-(Cr, V bcc phases has been found. Using this model it has been predicted that static displacements of Fe - atoms in alloy matrix increase with increasing the of CS number and result in reducing of the area of coherent dissipation (ACD size with growth of the dimension factor (DF in the Fe-(Cr, V, Mo, W systems in agreement with the X-ray experiments. It has been shown theoretically that anisotropy of spin- density in bcc lattice Fe and DF in binary Fe - (Cr, V, Mo, W systems is main factor for origins of segregations on small angle boundaries of ACD and sub-grains boundaries To prevent the coagulation of both ACD and sub-grains, and to increase the strength of alloys, it is advisable to add oxide dispersion particles into ferrite steel taking into account their chemical compatibility and coherent interfacing with the crystalline lattice of a ferrite matrix. Application of phase diagrams for binary and ternary the Fe-(Y, Zr-O systems to verify chemical compatibility of oxide dispersion particles with ferrite matrix have been discussed

  16. Abnormal Grain Growth in the Heat Affected Zone of Friction Stir Welded Joint of 32Mn-7Cr-1Mo-0.3N Steel during Post-Weld Heat Treatment

    Directory of Open Access Journals (Sweden)

    Yijun Li

    2018-04-01

    Full Text Available The abnormal grain growth in the heat affected zone of the friction stir welded joint of 32Mn-7Cr-1Mo-0.3N steel after post-weld heat treatment was confirmed by physical simulation experiments. The microstructural stability of the heat affected zone can be weakened by the welding thermal cycle. It was speculated to be due to the variation of the non-equilibrium segregation state of solute atoms at the grain boundaries. In addition, the pressure stress in the welding process can promote abnormal grain growth in the post-weld heat treatment.

  17. Machining-induced deformation in stepped specimens of PH 13-8 Mo, 18 nickel maraging steel grade 200T1 and grain-refined HP 9-4-20

    Science.gov (United States)

    Wigley, D. A.

    1985-01-01

    The results of a study to evaluate the dimensional changes created during machining and subsequent cycling to cryogenic temperatures for three different metallic alloys are presented. Experimental techniques are described and results presented for 18 Ni Grade 200 maraging steel, PH-13-8 Mo stainless steel, and Grain-refined HP 9-4-20.

  18. Effect of Grain Boundary Alpha on Mechanical Properties of Ti5.4Al3Mo1V Alloy

    Science.gov (United States)

    Kumar, Kurnala Naresh; Muneshwar, Pravin; Singh, Satish Kumar; Jha, Abhay K.; Pant, Bhanu; George, Koshy M.

    2015-06-01

    The article brings out the correlation between the microstructure and mechanical properties of Ti5.4Al3Mo1V (VT14 alloy) high-strength alpha beta titanium alloy. The specimens were solution treated above the beta transus temperature of the alloy (980°C and 1000°C) for 45 min and cooled at different rates (water quenched, air cooled, and furnace cooled) to ambient temperature. The specimens were polished, and the microstructural observations under optical microscopy resulted in a discontinuous alpha phase and a continuous network of alpha for 980°C and 1000°C beta-annealed conditions, respectively. Mechanical properties like tensile and impact were evaluated for a 980°C beta-annealed condition. The fracture morphology features of failed impact specimens were compared with a mill annealed product. From the tensile strength data, it was observed that the strength achieved is maximum in the water-quenched condition (1291-1308 MPa) and lowest in the furnace-cooled condition (895-905 MPa), whereas the impact strength is highest in the furnace-cooled condition (8.03-8.7 gm/cm2), which is comparable with the air-cooled condition (7.3-8.5 kg/cm2), and lowest for the water-quenched condition (2.5-3.1 kg/cm2). The current study is an attempt to correlate the mechanical properties to the heat treatment and thereby to the microstructure.

  19. A study on the degradation evaluation for Cr-Mo steel in power plants by grain deformation measuring and ultrasonic method

    International Nuclear Information System (INIS)

    Lee, Sang Guk

    2002-01-01

    Boiler high-temperature pipelines such as main steam pipe, header and steam drum in fossil power plants are degraded by creep and thermal fatigue damage due to severe operating conditions such as high temperature and high pressure for an extended period time. Conventional measurement techniques for measuring creep damage have low practicality and applied only to component surfaces with good accessibility. In this paper, the grain deformation and ultrasonic measurement for degraded specimens were carried out for the purpose of a practical evaluation for creep damage. Relationships between the grain deformation and ultrasonic properties for material degradation were established through these two measuring methods. As a result of grain deformation and ultrasonic tests for crept specimens, we conformed that deformation index and sound velocity linearly decreased, and also attenuation coefficient and ultrasonic noise linearly increased in proportion to the increase of creep degradation, respectively.

  20. Inter-grain tunnelling in the half-metallic double-perovskites Sr2BB'O6 (BB'= FeMo, FeRe, CrMo, CrW, CrRe

    Directory of Open Access Journals (Sweden)

    Fisher B.

    2014-07-01

    Full Text Available The zero-field conductivities (σ of polycrystalline title materials, are governed by intergrain transport. In the majority of cases their σ(T can be described by the "fluctuation induced tunnelling" model. Analysis of the results in terms of this model reveals two remarkable features: 1. For all Sr2FeMoO6 samples of various microstructures, the tunnelling constant (barrier width × inverse decay-length of the wave-function is ~ 2, indicating the existence of an intrinsic insulating boundary layer with a well-defined electronic (and magnetic structure. 2. The tunnelling constant for all cold-pressed samples decreases linearly with increasing magnetic-moment/formula-unit.

  1. Microstructure and properties of MoSi2-MoB and MoSi2-Mo5Si3 molybdenum silicides

    International Nuclear Information System (INIS)

    Schneibel, J.H.; Sekhar, J.A.

    2003-01-01

    MoSi 2 -based intermetallics containing different volume fractions of MoB or Mo 5 Si 3 were fabricated by hot-pressing MoSi 2 , MoB, and Mo 5 Si 3 powders in vacuum. Both classes of alloys contained approximately 5 vol.% of dispersed silica phase. Additions of MoB or Mo 5 Si 3 caused the average grain size to decrease. The decrease in the grain size was typically accompanied by an increase in flexure strength, a decrease in the room temperature fracture toughness, and a decrease in the hot strength (compressive creep strength) measured around 1200 deg. C, except when the Mo 5 Si 3 effectively became the major phase. Oxidation measurements on the two classes of alloys were carried out in air. Both classes of alloys were protected from oxidation by an in-situ adherent scale that formed on exposure to high temperature. The scale, although not analyzed in detail, is commonly recognized in MoSi 2 containing materials as consisting mostly of SiO 2 . The MoB containing materials showed an increase in the scale thickness and the cyclic oxidation rate at 1400 deg. C when compared with pure MoSi 2 . However, in contrast with the pure MoSi 2 material, oxidation at 1400 deg. C began with a weight loss followed by a weight gain and the formation of the protective silica layer. The Mo 5 Si 3 containing materials experienced substantial initial weight losses followed by regions of small weight changes. Overall, the MoB and Mo 5 Si 3 additions to MoSi 2 tended to be detrimental for the mechanical and oxidative properties

  2. Giant grains

    International Nuclear Information System (INIS)

    Leitch-Devlin, M.A.; Millar, T.J.; Williams, D.A.

    1976-01-01

    Infrared observations of the Orion nebula have been interpreted by Rowan-Robinson (1975) to imply the existence of 'giant' grains, radius approximately 10 -2 cm, throughout a volume about a parsec in diameter. Although Rowan-Robinson's model of the nebula has been criticized and the presence of such grains in Orion is disputed, the proposition is accepted, that they exist, and in this paper situations in which giant grains could arise are examined. It is found that, while a giant-grain component to the interstellar grain density may exist, it is difficult to understand how giant grains arise to the extent apparently required by the Orion nebula model. (Auth.)

  3. Impact of reduced graphene oxide on MoS{sub 2} grown by sulfurization of sputtered MoO{sub 3} and Mo precursor films

    Energy Technology Data Exchange (ETDEWEB)

    Pacley, Shanee, E-mail: shanee.pacley@us.af.mil; Brausch, Jacob; Beck-Millerton, Emory [U.S. Air Force Research Laboratory (AFRL)/Wright Patterson Air Force Base, Wright Patterson, Ohio 45433-7707 (United States); Hu, Jianjun; Jespersen, Michael [University of Dayton Research Institute, 300 College Park, Dayton, Ohio 45469 (United States); Hilton, Al [Wyle Laboratories, 4200 Colonel Glenn Hwy, Beavercreek, Ohio 45431 (United States); Waite, Adam [University Technology Corporation, 1270 N Fairfield Rd., Beavercreek, Ohio 45432 (United States); Voevodin, Andrey A. [Department of Materials Science and Engineering, University of North Texas, 1155 Union Circle, Denton, Texas 76203 (United States)

    2016-07-15

    Monolayer molybdenum disulfide (MoS{sub 2}), a two dimensional semiconducting dichalcogenide material with a bandgap of 1.8–1.9 eV, has demonstrated promise for future use in field effect transistors and optoelectronics. Various approaches have been used for MoS{sub 2} processing, the most common being chemical vapor deposition. During chemical vapor deposition, precursors such as Mo, MoO{sub 3}, and MoCl{sub 5} have been used to form a vapor reaction with sulfur, resulting in thin films of MoS{sub 2}. Currently, MoO{sub 3} ribbons and powder, and MoCl{sub 5} powder have been used. However, the use of ribbons and powder makes it difficult to grow large area-continuous films. Sputtering of Mo is an approach that has demonstrated continuous MoS{sub 2} film growth. In this paper, the authors compare the structural properties of MoS{sub 2} grown by sulfurization of pulse vapor deposited MoO{sub 3} and Mo precursor films. In addition, they have studied the effects that reduced graphene oxide (rGO) has on MoS{sub 2} structure. Reports show that rGO increases MoS{sub 2} grain growth during powder vaporization. Herein, the authors report a grain size increase for MoS{sub 2} when rGO was used during sulfurization of both sputtered Mo and MoO{sub 3} precursors. In addition, our transmission electron microscopy results show a more uniform and continuous film growth for the MoS{sub 2} films produced from Mo when compared to the films produced from MoO{sub 3}. Atomic force microscopy images further confirm this uniform and continuous film growth when Mo precursor was used. Finally, x-ray photoelectron spectroscopy results show that the MoS{sub 2} films produced using both precursors were stoichiometric and had about 7–8 layers in thickness, and that there was a slight improvement in stoichiometry when rGO was used.

  4. Microstructure of sintered ND–Fe–Ga–B magnets with Mo and MoS2 addition

    International Nuclear Information System (INIS)

    Li, W.F.; Gabay, A.M.; Marinescu-Jasinski, M.; Liu, J.F.; Ni, C.; Hadjipanayis, G.C.

    2012-01-01

    The effect of Mo and MoS 2 additions on the magnetic and microstructure properties has been investigated in Nd–Fe–Ga–B sintered magnets. Coercivity can be increased by both the additions, but the MoS 2 addition provides the larger increase per Mo atom for up to 0.6 at.% Mo. Microstructure investigation reveals a new amorphous intergranular Ga rich phase. This phase forms a thin layer in the grain boundaries and leads to a wetting behavior of the grain boundary phase, therefore increasing the coercivity. Molybdenum addition in the form of MoS 2 is found to modify the Nd 2 Fe 14 B phase, rather than form new minority phases, and the coercivity enhancement of the magnet is due to the increased anisotropy field of the hard magnetic phase. - Highlights: ► Coercivity of Nd–Fe–Ga–B alloys can be increased by both Mo and MoS 2 addition. ► MoS 2 addition is proved to be more effective to improve the coercivity. ► An amorphous Ga rich layer was found in the grain boundary, which can increase the coercivity.

  5. Effect of starting composition on formation of MoSi2–SiC ...

    Indian Academy of Sciences (India)

    20 h). On the other hand, annealing led to transformation of HTP to low temperature polymorph (LTP) of MoSi2. Mo5Si3 was formed during annealing as a product of a reaction between MoSi2 and excess graphite. Mean grain size <50 nm was ...

  6. Grain refinement of aluminum and its alloys

    International Nuclear Information System (INIS)

    Zaid, A.I.O.

    2001-01-01

    Grain refinement of aluminum and its alloys by the binary Al-Ti and Ternary Al-Ti-B master alloys is reviewed and discussed. The importance of grain refining to the cast industry and the parameters affecting it are presented and discussed. These include parameters related to the cast, parameters related to the grain refining alloy and parameters related to the process. The different mechanisms, suggested in the literature for the process of grain refining are presented and discussed, from which it is found that although the mechanism of refining by the binary Al-Ti is well established the mechanism of grain refining by the ternary Al-Ti-B is still a controversial matter and some research work is still needed in this area. The effect of the addition of other alloying elements in the presence of the grain refiner on the grain refining efficiency is also reviewed and discussed. It is found that some elements e.g. V, Mo, C improves the grain refining efficiency, whereas other elements e.g. Cr, Zr, Ta poisons the grain refinement. Based on the parameters affecting the grain refinement and its mechanism, a criterion for selection of the optimum grain refiner is forwarded and discussed. (author)

  7. Magnetothermopower in A2−xLaxFeMoO6 (A = Sr, Ba

    Directory of Open Access Journals (Sweden)

    G. V. M. Williams

    2017-01-01

    Full Text Available A magnetothermopower has been observed in electronically spin-polarized polycrystalline Sr2-xLaxFeMoO6 and Ba2FeMoO6. The magnetothermopower is linear up to ~50 K for Sr2-xLaxFeMoO6 and linear up to ~270 K for Ba2FeMoO6. We suggest that the magnetothermopower may arise from a spin-tunneling magnetothermopower between the grains.

  8. Comparative study of NiW, NiMo and MoW prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Gonzalez, G.; Sagarzazu, A.; Villalba, R.; Ochoa, J.

    2007-01-01

    The present work concern the amorphisation process induced by mechanical alloying in the NiW, NiMo and MoW systems. The alloys chosen combine a group of transition elements varying from very similar atomic radius and electronic valences (MoW) to different ones (NiW and NiMo). The three systems achieved an amorphous state after 50 h of milling. The mechanism of amorphisation proposed for NiW and NiMo was the combined effect of an excess concentration of the solute atoms entering into the structure of one of the elements and a critical concentration of defects. Continuous formation of an amorphous phase at the interface of the crystalline phase was observed during the process. MoW seems to amorphize by continuous reduction of grain size down to a critical value where the amorphisation takes place

  9. Microstructures and properties of rare earth-particles reinforced MoSi2 composites

    International Nuclear Information System (INIS)

    Zhang, H.; Liu, X.; Ning, A.

    2001-01-01

    MoSi 2 and rare earth (RE)/MoSi 2 composites were synthesized by mechanical alloying (MA) and self-propagating high-temperature synthesis (SHS) techniques. Their properties of hot pressing disks were measured, such as hardness and fracture toughness at ambient temperature and compressive yield strength at elevated temperature. The responded microstructures were observed by using SEM and x-ray. the results show that the room temperature properties of MoSi 2 matrix are obviously reinforced by addition of rare earth element (especially, when it is of 0.9 wt.%). The toughening mechanism in RE/MoSi 2 composite include fine-grained, microcrack, crack deflection, crack microbridging, crack bowing and branching, and the strengthening mechanism is fine-grained. But RE/MoSi 2 composites only synthesized by SHS have higher yield strength at elevated temperature, with grain-coarsened and dispersion strengthening mechanisms. (author)

  10. Characterization of U-Mo Foils for AFIP-7

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Danny J.; Ermi, Ruby M.; Schemer-Kohrn, Alan L.; Overman, Nicole R.; Henager, Charles H.; Burkes, Douglas; Senor, David J.

    2012-11-07

    Twelve AFIP in-process foil samples, fabricated by either Y-12 or LANL, were shipped from LANL to PNNL for potential characterization using optical and scanning electron microscopy techniques. Of these twelve, nine different conditions were examined to one degree or another using both techniques. For this report a complete description of the results are provided for one archive foil from each source of material, and one unirradiated piece of a foil of each source that was irradiated in the Advanced Test Reactor. Additional data from two other LANL conditions are summarized in very brief form in an appendix. The characterization revealed that all four characterized conditions contained a cold worked microstructure to different degrees. The Y-12 foils exhibited a higher degree of cold working compared to the LANL foils, as evidenced by the highly elongated and obscure U-Mo grain structure present in each foil. The longitudinal orientations for both of the Y-12 foils possesses a highly laminar appearance with such a distorted grain structure that it was very difficult to even offer a range of grain sizes. The U-Mo grain structure of the LANL foils, by comparison, consisted of a more easily discernible grain structure with a mix of equiaxed and elongated grains. Both materials have an inhomogenous grain structure in that all of the characterized foils possess abnormally coarse grains.

  11. Intake and apparent digestibility of rations containing different proportions of Coastcross (Cynodon dactylon (L. Pers. hay plus ground soybean grain and sheep eating behaviour/ Consumo e digestibilidade aparente de rações com diferentes proporções de feno de capim Coastcross (Cynodon dactylon (L. Pers. e soja crua moída e comportamento alimentar de ovinos

    Directory of Open Access Journals (Sweden)

    Tiago Rodrigues Casimiro

    2006-07-01

    Full Text Available The aims of this experiment were to determine the average daily intake (ADI and the apparent digestibility coefficient (ADC of rations containing two levels of coastcross hay and ground soybean grain, as well as, to study the behavior of sheep fed on these rations. Ten wethers averaging 40.0 kg of live weight were allocated in feeding trial cages for this experiment. A completely randomized design with two treatments (T1= 80% coastcross hay + 20% soybean grain and T2= 60% coast cross hay + 40% soybean grain and five replicates, were used. The treatments were evaluated under two feeding systems (voluntary and restrict. There were two experimental periods of seven days with fifteen days of previous adaptation each. The animals were fed twice a day with rations containing half of the estimated daily intake. The behaviours studied were times spent eating, ruminating and resting in a five minutes interval observation during twelve hours. There were no significant differences (P>0.05 between treatments for nutrientsADI but for crude protein and ether extract (EE. The ADC for dry matter (DM, fiber (F and total carbohydrates (TC were significantly greater (PO objetivo deste trabalho foi determinar o consumo médio e a digestibilidade aparente dos nutrientes de rações contendo dois níveis de feno de capim coast-cross e soja crua moída, bem como estudar o comportamento de ovinos alimentados com essas rações. Foram utilizados dez ovinos machos, castrados, com peso vivo médio de 40,0 kg, em delineamento experimental inteiramente casualizado com dois tratamentos (T (T1= 80% de feno de coastcross picado + 20% de soja crua moída e T2= 60% de feno de coastcross picado + 40% de soja crua moída e cinco repetições. Os tratamentos foram avaliados em regimes de consumo voluntário e consumo restrito. O ensaio compreendeu um período de adaptação de 15 dias, seguido de dois períodos de coleta de sete dias cada. A ração foi fornecida em duas refei

  12. High performance Mo adsorbent PZC

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1998-10-01

    We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

  13. MoS₂ decoration by Mo-atoms and the MoS₂-Mo-graphene heterostructure: a theoretical study.

    Science.gov (United States)

    Kvashnin, D G; Sorokin, P B; Seifert, G; Chernozatonskii, L A

    2015-11-21

    Here we propose a completely new covalent heterostructure based on graphene and self-decorated MoS2 monolayers. Detailed investigation of the decoration process of the MoS2 surface by Mo adatoms was performed using first principles DFT methods. Comparison between valence-only and semicore pseudopotentials was performed to correctly describe the interaction between Mo adatoms and the MoS2 surface. It was found that self-decoration by Mo atoms is favorable from an energetic point of view. We studied in detail various decoration paths of Mo atoms on the MoS2 surface. The strong variation of electronic properties after the decoration of MoS2 was found. The impact of the presence of Mo adatoms on the electronic properties of the graphene/MoS2 heterostructure was shown.

  14. Dynamic Abnormal Grain Growth in Refractory Metals

    Science.gov (United States)

    Noell, Philip J.; Taleff, Eric M.

    2015-11-01

    High-temperature plastic deformation of the body-centered cubic (BCC) refractory metals Mo and Ta can initiate and propagate abnormal grains at significantly lower temperatures and faster rates than is possible by static annealing alone. This discovery reveals a new and potentially important aspect of abnormal grain growth (AGG) phenomena. The process of AGG during plastic deformation at elevated temperatures, termed dynamic abnormal grain growth (DAGG), was observed at homologous temperatures between 0.52 and 0.72 in both Mo and Ta sheet materials; these temperatures are much lower than those for previous observations of AGG in these materials during static annealing. DAGG was used to repeatedly grow single crystals several centimeters in length. Investigations to date have produced a basic understanding of the conditions that lead to DAGG and how DAGG is affected by microstructure in BCC refractory metals. The current state of understanding for DAGG is reviewed in this paper. Attention is given to the roles of temperature, plastic strain, boundary mobility and preexisting microstructure. DAGG is considered for its potential useful applications in solid-state crystal growth and its possibly detrimental role in creating undesired abnormal grains during thermomechanical processing.

  15. MoEDAL expands

    CERN Multimedia

    Anaïs Schaeffer

    2011-01-01

    The MoEDAL collaboration deployed a test array of 18 plastic Nuclear Track Etch Detector (NTD) stacks – covering an area of 1 m2 – in the MoEDAL/VELO cavern at Point 8 of the LHC ring in November 2009. This small array was supplemented by a further 110 stacks this past January. The MoEDAL test array, which now covers an area of 8 m2, will reveal its secrets early in 2013. The full MoEDAL detector will be installed in the next long shutdown of the LHC in 2013.   View of the MoEDAL detectors installed at Point 8 of the LHC ring in January 2011. MoEDAL (Monopole and Exotics Detector At the LHC), the seventh LHC experiment, was approved by the CERN Research Board at the end of 2009. Its goal is to search for very specific exotics such as highly ionising massive stable (or pseudo-stable) particles with conventional electrical charge and magnetic monopoles. “The main LHC experiments are designed to detect conventionally charged particles, with conventional ionisation patte...

  16. Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm₂O₃ Powder Mixtures during Ball Milling.

    Science.gov (United States)

    Luo, Yong; Ran, Guang; Chen, Nanjun; Shen, Qiang; Zhang, Yaoli

    2016-10-15

    The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt %) Tm₂O₃ powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm₂O₃ to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm₂O₃ was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O) was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt %) Tm₂O₃, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O) solid solution.

  17. Mechanical properties of fine-grained sintered molybdenum alloy processed by mechanical alloying

    International Nuclear Information System (INIS)

    Takida, T.; Kurishita, H.; Mabuchi, M.; Igarashi, T.; Doi, Y.; Nagae, T.

    2001-01-01

    In order to improve the low-temperature toughness and room- and high-temperature strengths of molybdenum (Mo), sintered Mo alloys with fine grains and fine, dispersed particles were fabricated by hot isostatic pressing of spark plasma sintering with mechanically alloyed powder of Mo and 0.8 mol % ZrC or TaC (designated ZRC08 and TAC08). The fabricated Mo alloys showed no significant grain growth even after annealing at 2470 K for 3.6 ks due to the pinning effect of the particles against grain boundary migration. For the Mo alloys the impact three-point bending test was performed at 270 to 470 K and at 5 m s -1 and the static tensile test at 300 to 1970 K and at 4.2 x 10 - % to 8.3 x 10-2 s -1 . The fabricated alloys exhibited lower ductile-to brittle transition temperatures and higher tensile strengths up to 1770 K than fully recrystallized pure Mo. In particular, TAC08 was superior in low-temperature toughness and ZRC08 was superior in room- and high-temperature strengths. Furthermore, ZRC08 showed a large elongation of 551 % at 1770 K. These excellent mechanical properties of the fabricated Mo alloys are attributable to the fine-grained microstructure and grain-boundary strengthening by the fine particles. (author)

  18. The Tribological Performance of CrMoN/MoS2 Solid Lubrication Coating on a Piston Ring

    Directory of Open Access Journals (Sweden)

    Yuelan Di

    2017-05-01

    Full Text Available In order to improve the tribological properties of an engine piston ring and enhance its service life, magnetron sputtering technology and low temperature ion sulphurizing treatment technology were used to prepare CrMoN/MoS2 solid lubricant coating on the surface of an engine piston ring. The morphologies and compositions of the surface and cross-section of the sulfuration layer were analyzed by field emission scanning electron microscopy (FESEM, and wear property under high load, high speed and high temperature conditions were tested by a SRV®4 friction and wear testing machine. The results show that the CrMoN/MoS2 composite coatings appear as a dense grain structure, and the coating is an ideal solid lubrication layer that possesses an excellent high temperature wear resistance, reducing the engine operating temperature abrasion effectively and prolonging the service life of the engine.

  19. Microbiota of kefir grains

    Directory of Open Access Journals (Sweden)

    Tomislav Pogačić

    2013-03-01

    Full Text Available Kefir grains represent the unique microbial community consisting of bacteria, yeasts, and sometimes filamentous moulds creating complex symbiotic community. The complexity of their physical and microbial structures is the reason that the kefir grains are still not unequivocally elucidated. Microbiota of kefir grains has been studied by many microbiological and molecular approaches. The development of metagenomics, based on the identification without cultivation, is opening new possibilities for identification of previously nonisolated and non-identified microbial species from the kefir grains. Considering recent studies, there are over 50 microbial species associated with kefir grains. The aim of this review is to summarise the microbiota composition of kefir grains. Moreover, because of technological and microbiological significance of the kefir grains, the paper provides an insight into the microbiological and molecular methods applied to study microbial biodiversity of kefir grains.

  20. Thermal conductivity of MoS2 polycrystalline nanomembranes

    Science.gov (United States)

    Sledzinska, M.; Graczykowski, B.; Placidi, M.; Saleta Reig, D.; El Sachat, A.; Reparaz, J. S.; Alzina, F.; Mortazavi, B.; Quey, R.; Colombo, L.; Roche, S.; Sotomayor Torres, C. M.

    2016-09-01

    Heat conduction in 2D materials can be effectively engineered by means of controlling nanoscale grain structure. A favorable thermal performance makes these structures excellent candidates for integrated heat management units. Here we show combined experimental and theoretical studies for MoS2 nanosheets in a nanoscale grain-size limit. We report thermal conductivity measurements on 5 nm thick polycrystalline MoS2 by means of 2-laser Raman thermometry. The free-standing, drum-like MoS2 nanomembranes were fabricated using a novel polymer- and residue-free, wet transfer, in which we took advantage of the difference in the surface energies between MoS2 and the growth substrate to transfer the CVD-grown nanosheets. The measurements revealed a strong reduction in the in-plane thermal conductivity down to about 0.73 ± 0.25 {{{W}}{{m}}}-1 {{{K}}}-1. The results are discussed theoretically using finite elements method simulations for a polycrystalline film, and a scaling trend of the thermally conductivity with grain size is proposed.

  1. Marketing Farm Grain Crops.

    Science.gov (United States)

    Ridenour, Harlan E.

    This vocational agriculture curriculum on grain marketing contains three parts: teacher guide, student manual, and student workbook. All three are coordinated and cross-referenced. The course is designed to give students of grain marketing a thorough background in the subject and provide practical help in developing grain marketing strategies for…

  2. Effect of Ultrasonic Treatment on the Solidification Microstructure of Die-Cast 35CrMo Steel

    Directory of Open Access Journals (Sweden)

    Gen Liang

    2016-10-01

    Full Text Available The effects of ultrasonic treatment (UST on the solidification microstructure of a 35CrMo steel cast ingot were investigated. To avoid the erosion of a high-temperature melt, a T-shaped ultrasonic waveguide unit was used to introduce ultrasonic vibrations into a 35CrMo steel die casting melt. The experimental results show that the microstructure of the ingot was refined by ultrasonic treatment. While the microstructure of untreated 35CrMo steel is coarse dendritic grains, after the introduction of ultrasonic treatment, the solidification microstructure transforms from coarse dendritic to equiaxed grains, and the dendrites are also refined. Samples from different positions of the ingots were subjected to different ultrasonic effects, and the effects on grain refinement also varied due to the severe attenuation of the ultrasound in the melt. The mechanisms of grain refinement using ultrasonic treatment for 35CrMo steel melt are presented.

  3. Thermal compatibility studies of unirradiated U-Mo alloys dispersed in aluminum

    International Nuclear Information System (INIS)

    Lee, D.B.; Kim, K.H.; Kim, C.K.

    1997-01-01

    The thermal compatibility of centrifugally atomized U-Mo alloys with aluminium has been studied. The results of the investigations show that the U-2 wt% Mo/aluminum dispersions increase in volume by 26% at 400 C after 2000 h. This large volume change is mainly due to the formation of voids and cracks resulting from nearly complete interdiffusion of U-Mo and aluminum. No significant dimensional changes occur in the U-10 wt% Mo/aluminum dispersions. Interdiffusion between U-10 wt% Mo and aluminum is found to be minimal. The different diffusion behavior is primarily due to the fact that U-10 wt% Mo particles are much more supersaturated with substitutional molybdenum than U-2 wt% Mo particles. The aluminum diffuses into the U-2 wt% Mo particles relatively rapidly along grain boundary with nearly pure uranium, forming UAl 3 almost fully throughout the 2000 h anneal, whereas the molybdenum supersaturated in the U-10 wt% Mo particles inhibits the diffusion of aluminum atoms. U-10 wt% Mo displays superior thermal compatibility with aluminum compared to U-2 wt% Mo. (orig.)

  4. High heat load properties of TiC dispersed Mo alloys

    International Nuclear Information System (INIS)

    Tokunaga, Kazutoshi; Yoshida, Naoaki; Miura, Yasushi; Kurishita, Hiroaki; Kitsunai, Yuji; Kayano, Hideo.

    1996-01-01

    Electron beam high heat load experiment of new developed three kinds of TiC dispersed Mo alloys (Mo-0.1wt%TiC, Mo-0.5wt%TiC and Mo-1.0wt%TiC) was studied so as to evaluate it's high heat load at using as the surface materials of divertor. The obtained results indicated that cracks were not observed by embrittlement by recrystallization until about 2200degC of surface temperature and the gas emission properties were not different from sintered molibdenum. However, at near melting point, deep cracks on grain boundary and smaller gas emission than that of sintered Mo were observed. So that, we concluded that TiC dispersed Mo alloy was good surface materials used under the conditions of the stationary heat flux and less than the melting point, although not good one to be melted under nonstationary large heat flux. (S.Y.)

  5. WORLD GRAIN TRADE

    Directory of Open Access Journals (Sweden)

    Emilia Mary Bălan

    2017-04-01

    Full Text Available Grain is part of agricultural commodities and is of utmost importance for world agriculture,since it is the essential element of food and animal feed. Against this background, grain trade among countries of the world is dynamic and represents about 10% of global trade in food products.This article examines global grain trade both in terms of quantitative and qualitative developments, and highlights the most important competitor countries in this sector. It also details the patterns of grain trade for the world's main exporters and importers of such commodities.Two distinct sections of the research relate to the evolution of the primary grain quotations(wheat, corn, barley, rice and sorghum at the most representative international agricultural commodities markets (Chicago Board of Trade, based on a comprehensive statistical analysis, and the short-term forecasts for global grain trade, respectively.

  6. Controllable Growth of Monolayer MoS2 and MoSe2 Crystals Using Three-temperature-zone Furnace

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu

    2017-12-01

    Monolayer molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) have attracted a great attention for their exceptional electronic and optoelectronic properties among the two dimensional family. However, controllable synthesis of monolayer crystals with high quality needs to be improved urgently. Here we demonstrate a chemical vapor deposition (CVD) growth of monolayer MoS2 and MoSe2 crystals using three-temperature-zone furnace. Systematical study of the effects of growth pressure, temperature and time on the thickness, morphology and grain size of crystals shows the good controllability. The photoluminescence (PL) characterizations indicate that the as-grown monolayer MoS2 and MoSe2 crystals possess excellent optical qualities with very small full-width-half-maximum (FWHM) of 96 me V and 57 me V, respectively. It is comparable to that of exfoliated monolayers and reveals their high crystal quality. It is promising that our strategy should be applicable for the growth of other transition metal dichalcogenides (TMDs) monolayer crystals.

  7. RoMo

    DEFF Research Database (Denmark)

    Pedersen, Esben Warming; Hornbæk, Kasper

    2011-01-01

    In TUIs, physical/digital conflicts can occur when the digital model does not match the model implied by the spatial lay- out of tangibles. We show how tangible tabletop interfaces (TTI) can be modified to allow robot movement of tangi- bles, thereby avoiding conflicts. We present RoMo, an open...... source Java library that allow existing TTI applications to perform robot movement, and demonstrate its functionality with three applications....

  8. Nanocrystalline electrodeposited Ni-Mo-C cathodes for hydrogen production

    International Nuclear Information System (INIS)

    Hashimoto, K.; Sasaki, T.; Meguro, S.; Asami, K.

    2004-01-01

    Tailoring active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. The carbon addition to Ni-Mo alloys decreased the nanocrystalline grain size and remarkably enhanced the activity for hydrogen evolution, changing the mechanism of hydrogen evolution. The Tafel slope of hydrogen evolution was about 35 mV per decade. This suggested that the rate-determining step is desorption of adsorbed hydrogen atoms by recombination. As was distinct from the binary Ni-Mo alloys, after open circuit immersion, the overpotential, that is, the activity of nanocrystalline Ni-Mo-C alloys for hydrogen evolution was not changed, indicating the sufficient durability in the practical electrolysis

  9. Microstructure and Mechanical Properties of Highly Alloyed FeCrMoVC Steel Fabricated by Spark Plasma Sintering

    Science.gov (United States)

    Oh, Seung-Jin; Jun, Joong-Hwan; Lee, Min-Ha; Shon, In-Jin; Lee, Seok-Jae

    2018-03-01

    In this study, we successfully fabricated highly alloyed FeCrMoVC specimens within 2 min by using the spark plasma sintering (SPS) method. The densities of the sintered specimens were almost identical to their theoretical values. Fine (Mo, V)-rich carbides with lamellar structure were precipitated along the grain boundaries of the as-sintered specimen, whereas relatively large carbides were formed additionally in the transgranular region during the tempering treatment. Compared with the specimen produced by a conventional casting method, the FeCrMoVC specimens from SPS showed smaller grain size with finer carbides and higher hardness values.

  10. Presolar Grains in Indarch

    Science.gov (United States)

    Gao, X.; Nittler, L. R.; Swan, P. D.; Walker, R. M.

    1995-09-01

    We report results for the EH(4) Indarch. Earlier work [1] found 20 micrometers clumps of sub-micron SiC whose presolar nature was inferred from step-wise combustion, noble gas [2], and ion probe isotopic measurements. Our results indicate that the clumps were an artifact of sample preparation. Our sample was first cleaned using 6N HCl, and water and isopropanol rinses, then powdered and reacted with HCl-HF/HCl, KOH, and H3BO3-HCl/HCl giving a C-rich residue 1.14 wt.% of the original. X-ray mapping showed SiC grains and 5x as many Si3N4 grains, but no fine-grained clumps. Large (6 micrometers to 20 micrometers) C-rich spheroids were also present. The sample was further treated with KOH/HNO3 and NH3H2O; attempts to do density-separates were unsuccessful. An aliquot was treated with perchloric acid and separated into 1 micrometer fractions. SEM-EDS measurements of 73 (1 micrometer) grains with the addition of 2 spinel and one Al2O3 grains. The whole rock concentration of SiC was 5.8 ppm, higher than previous determinations [1,3,9]. Confirming earlier suggestions [1,2], we find that SiC in Indarch is much finer-grained than in Murchison; about 2/3 of the mass is in grains size-sorting in the nebula or selective destruction of fine-grained material. Ion probe measurements of 22 (1-3 micrometers) grains gave isotopic results in the range previously measured for Murchison SiCs [4]. Several normal Si3N4 grains (>1 micron) were measured; probably exsolution products similar to those in Qingzhen [7]. Ion mapping was used to search for presolar oxide grains using previously developed techniques [5]. Seven candidate grains out of ~1000 were found. Multiple imaging confirmed an ^(16)O/^(18)O anomaly in one spinel grain - the first presolar oxide found in an E chondrite. Although the proportion of oxide grains relative to SiC is smaller, the fraction of anomalous oxide grains is not strikingly different in Indarch than in Murchison (1/1000) or Tieschitz (1/300). Prior ion probe

  11. Grains and Starchy Vegetables

    Science.gov (United States)

    ... Every time you choose to eat a starchy food, make it count! Leave the processed white flour-based products, especially the ones with added ... wheat grain is ground up. "Refined" flours like white and enriched wheat flour include only ... whole grain foods can be a challenge. Some foods only contain ...

  12. Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm2O3 Powder Mixtures during Ball Milling

    Directory of Open Access Journals (Sweden)

    Yong Luo

    2016-10-01

    Full Text Available The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt % Tm2O3 powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm2O3 was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt % Tm2O3, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O solid solution.

  13. Diffusion barrier performances of thin Mo, Mo-N and Mo/Mo-N films between Cu and Si

    International Nuclear Information System (INIS)

    Song Shuangxi; Liu Yuzhang; Mao Dali; Ling Huiqin; Li Ming

    2005-01-01

    In this work, we have studied the diffusion barrier performances of Mo, Mo-N and Mo/Mo-N metallization layers deposited by sputtering Mo in Ar/N 2 atmospheres, respectively. Samples were subsequently annealed at different temperatures ranging from 400 to 800 deg C in vacuum condition. The film properties and their suitability as diffusion barriers and protective coatings in silicon devices were characterized using four-point probe measurement, X-ray diffractometry, scanning electron microscopy, Auger electron spectroscopy and transmission electron microscopy analyses. Experimental results revealed that the Mo (20 nm)/Mo-N (30 nm) layer was able to prevent the diffusion reaction between Cu and Si substrate after being annealed at 600 deg C for 30 min. The adhesion between layers and the content of N atoms are the key parameters to improve the properties of Mo-based barrier materials. The Mo layer interposed between Cu and Mo-N diluted the high nitrogen concentration of the barrier and so enhanced the barrier performances

  14. Fission-induced recrystallization effect on intergranular bubble-driven swelling in U-Mo fuel

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Linyun; Mei, Zhi-Gang; Yacout, Abdellatif M.

    2017-10-01

    We have developed a mesoscale phase-field model for studying the effect of recrystallization on the gas-bubble-driven swelling in irradiated U-Mo alloy fuel. The model can simulate the microstructural evolution of the intergranular gas bubbles on the grain boundaries as well as the recrystallization process. Our simulation results show that the intergranular gas-bubble-induced fuel swelling exhibits two stages: slow swelling kinetics before recrystallization and rapid swelling kinetics with recrystallization. We observe that the recrystallization can significantly expedite the formation and growth of gas bubbles at high fission densities. The reason is that the recrystallization process increases the nucleation probability of gas bubbles and reduces the diffusion time of fission gases from grain interior to grain boundaries by increasing the grain boundary area and decreasing the diffusion distance. The simulated gas bubble shape, size distribution, and density on the grain boundaries are consistent with experimental measurements. We investigate the effect of the recrystallization on the gas-bubble-driven fuel swelling in UMo through varying the initial grain size and grain aspect ratio. We conclude that the initial microstructure of fuel, such as grain size and grain aspect ratio, can be used to effectively control the recrystallization and therefore reduce the swelling in U-Mo fuel.

  15. All About the Grains Group

    Science.gov (United States)

    ... Grains All about the Grains Group Print Share What foods are in the Grains Group? Any food made ... Whole Grains Food Gallery Take the Grains Quiz What Is MyPlate? Food Guide History MyPlate, MyWins Fruits All About the ...

  16. Microstructure and mechanical properties of Mo/ZrC in-situ composites

    International Nuclear Information System (INIS)

    Suzuki, T.; Nomura, N.; Hanada, S.

    2001-01-01

    Mo/ZrC in-situ composites with hyper-eutectic (Mo-40 mol%ZrC) and eutectic (Mo-16 mol%ZrC) compositions were synthesized by arc-melting blended Mo and ZrC powders and their microstructures and mechanical properties were investigated. Mo-40ZrC annealed at 1873 K for 70 h consists of coarse primary ZrC particles greater than 10 μm and eutectic of fine ZrC particles less than 1 μm and Mo solid solution with grain sizes of about 3 μm. In Mo-16ZrC fine ZrC particles with an average diameter of 600 nm are distributed in Mo solid solution, forming some colonies with sizes of several 10 μm. Yield stresses at a strain rate of 1.7 x 10 -4 s -1 for Mo-40ZrC are very high at high temperatures, especially above 1500 K, which are higher than those of monolithic ZrC and Mo-40TiC. Mo-40M exhibits good creep strength as compared with advanced ceramic matrix composites. Fracture toughness K Q for Mo-40ZrC and Mo-16ZrC at room temperature is evaluated to be 13.9 and 12.7 Mpa x m 1/2 by three point bending test, respectively, which is much higher than that of monolithic carbide (1 - 3 Mpa x m 1/2 ). (author)

  17. Interstellar grain chemistry

    International Nuclear Information System (INIS)

    Buch, V.

    1990-01-01

    This chapter discusses the chemical evolution and composition of dust in dense interstellar clouds. Studies use observations in the infrared, visible and ultraviolet spectral regions. These grains are thought to be made largely of highly disordered and/or composite materials. Recently acquired data on Halley's comet and on the structure, composition and spectral properties of interplanetary dust particles (IDP) are used to study grain chemistry. These substances are though to be similar to dense cloud dust. Dense clouds are thought to contain minerals, poorly crystallized carbonaceous/organic polymers, coating mineral grains and dirty ice mantles and the chemistry of these substances is considered. (UK)

  18. Kansas Agents Study Grain Marketing

    Science.gov (United States)

    Schoeff, Robert W.

    1973-01-01

    Author is an extension specialist in feed and grain marketing for Kansas State University. He describes a tour set up to educate members of the Kansas Grain and Feed Dealers' Association in the area of grain marketing and exporting. (GB)

  19. Structural, morphological, and optical characterizations of Mo, CrN and Mo:CrN sputtered coatings for potential solar selective applications

    Science.gov (United States)

    Ibrahim, Khalil; Mahbubur Rahman, M.; Taha, Hatem; Mohammadpour, Ehsan; Zhou, Zhifeng; Yin, Chun-Yang; Nikoloski, Aleksandar; Jiang, Zhong-Tao

    2018-05-01

    Mo, CrN, and Mo:CrN sputtered coatings synthesized onto silicon Si(100) substrates were investigated as solar selective surfaces and their potential applications in optical devices. These coatings were characterized using XRD, SEM, UV-vis, and FTIR techniques. XRD investigation, showed a change in CrN thin film crystallite characteristic due to Mo doping. Compared to the CrN coating, the Mo:CrN film has a higher lattice parameter and lower grain size of 4.19 nm and 106.18 nm, respectively. FESEM morphology confirmed the decrement in Mo:CrN crystal size due to Mo doping. Optical analysis showed that in the visible range of the solar spectrum, the CrN coatings exhibit the highest solar absorptance of 66% while the lowest thermal emittance value of 5.67 was recorded for the CrN coating doped with Mo. Consequently, the highest solar selectivity of 9.6, and the energy band-gap of 2.88 eV were achieved with the Mo-doped CrN coatings. Various optical coefficients such as optical absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constants, and energy loss functions of these coatings were also estimated from the optical reflectance data recorded in the wavelength range of 190-2300 nm.

  20. Electrostatic properties of few-layer MoS2 films

    Directory of Open Access Journals (Sweden)

    Guolin Hao

    2013-04-01

    Full Text Available Two-dimensional MoS2-based materials are considered to be one of the most attractive materials for next-generation nanoelectronics. The electrostatic properties are important in designing and understanding the performance of MoS2-based devices. By using Kelvin probe force microscopy, we show that few-layer MoS2 sheets exhibit uniform surface potential and charge distributions on their surfaces but have relatively lower surface potentials on the edges, folded areas as well as defect grain boundaries.

  1. Nanocrystalline formation in immiscible Cu-Mo system subjected to mechanical alloying.

    Science.gov (United States)

    Lee, Chung-Hyo; Lee, Seong-Hee

    2007-11-01

    The mechanical alloying process has been studied on the Cu-Mo system, the atomic pair of which is characterized by a positive heat of mixing of +19 kJ/mol. The EXAFS and X-ray diffraction measurements have been employed to analyze the structural changes taking place during milling. Two phases mixture of nanocrystalline fcc-Cu and bcc-Mo with a grain size of 10 nm has been formed by MA of Cu30Mo70 powders for 200 hours. The structural analysis based on the EXAFS spectra revealed that bcc and fcc crystal structure clearly do not change around Mo and Cu atoms up to 200 h of milling, respectively. Studies of the thermodynamical considerations by DSC analyses confirmed that the alloying does not occur even after 200 hours of MA in Cu-Mo system.

  2. Coated U(Mo) Fuel: As-Fabricated Microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Emmanuel Perez; Dennis D. Keiser, Jr.; Ann Leenaers; Sven Van den Berghe; Tom Wiencek

    2014-04-01

    As part of the development of low-enriched uranium fuels, fuel plates have recently been tested in the BR-2 reactor as part of the SELENIUM experiment. These fuel plates contained fuel particles with either Si or ZrN thin film coating (up to 1 µm thickness) around the U-7Mo fuel particles. In order to best understand irradiation performance, it is important to determine the starting microstructure that can be observed in as-fabricated fuel plates. To this end, detailed microstructural characterization was performed on ZrN and Si-coated U-7Mo powder in samples taken from AA6061-clad fuel plates fabricated at 500°C. Of interest was the condition of the thin film coatings after fabrication at a relatively high temperature. Both scanning electron microscopy and transmission electron microscopy were employed. The ZrN thin film coating was observed to consist of columns comprised of very fine ZrN grains. Relatively large amounts of porosity could be found in some areas of the thin film, along with an enrichment of oxygen around each of the the ZrN columns. In the case of the pure Si thin film coating sample, a (U,Mo,Al,Si) interaction layer was observed around the U-7Mo particles. Apparently, the Si reacted with the U-7Mo and Al matrix during fuel plate fabrication at 500°C to form this layer. The microstructure of the formed layer is very similar to those that form in U-7Mo versus Al-Si alloy diffusion couples annealed at higher temperatures and as-fabricated U-7Mo dispersion fuel plates with Al-Si alloy matrix fabricated at 500°C.

  3. Whole Grains and Fiber

    Science.gov (United States)

    ... of many nutrients: B vitamins (thiamin (Vitamin B1), riboflavin (Vitamin B2), niacin (Vitamin B3) and folate (Vitamin ... be the first ingredient listed. Choose whole grain foods that contain one of the following ingredients first ...

  4. Fine Grain Aluminum Superplasticity

    Science.gov (United States)

    1980-02-01

    Continua on ravaraa sida H nacaaaary and identify by block numbar) Superplastic aluminum, Superplasticity, Superplastic forming. High strength aluminum...size. The presence of precipitate particles also acts to impede grain boundary migration during recrystallization, further aiding in maintaining a

  5. SiMo Ductile Iron Crystallization Process

    Directory of Open Access Journals (Sweden)

    Stawarz M.

    2017-03-01

    Full Text Available The article presents crystallization process of silicon molybdenum ductile cast iron (SiMo. The alloy with 5% silicon content and with variable amounts of Mo in a range of 0-1% was chosen for the research. The carbon content in the analysed alloys did not exceed 3,1%. The studies of crystallization process were based on thermal - derivative analysis (TDA. Chemical composition of all examined samples was analysed with the use of LECO spectrometer. Additionally, the carbon and the sulphur content was determined basing on carbon and sulphur LECO analyser. For metallographic examination, the scanning electron microscopy (SEM with EDS analyser was used. Disclosed phases have been also tested with the use of X-ray diffraction. The results allowed the description of crystallization processes of silicon molybdenum ductile cast iron using thermal - derivative analysis (TDA. Conducted studies did not allow for the clear identification of all complex phases containing molybdenum, occurring at the grain boundaries. Therefore, the further stages of the research could include the use of a transmission electron microscope to specify the description of complex compounds present in the alloy.

  6. Grain Boundary Complexions

    Science.gov (United States)

    2014-05-01

    complexion transitions occur often in doped titanates, such as BaTiO3 and SrTiO3, and have been utilized to tailor microstructural develop- ment [275,276...Cantwell et al. / Acta Materialia 62 (2014) 1–48 Despite decades of research, efforts to identify grain boundary complexion transitions in pure metals via...evidence suggesting grain boundary complexion transitions in pure metals has existed for decades. For example, researchers have reported anomalies and

  7. Cyclic Oxidation of High Mo, Reduced Density Superalloys

    Directory of Open Access Journals (Sweden)

    James L. Smialek

    2015-11-01

    Full Text Available Cyclic oxidation was characterized as part of a statistically designed, 12-alloy compositional study of 2nd generation single crystal superalloys as part of a broader study to co-optimize density, creep strength, and cyclic oxidation. The primary modification was a replacement of 5 wt. % W by 7% or 12% Mo for density reductions of 2%–7%. Compositions at two levels of Mo, Cr, Co, and Re were produced, along with a midpoint composition. Initially, polycrystalline vacuum induction samples were screened in 1100 °C cyclic furnace tests using 1 h cycles for 200 h. The behavior was primarily delimited by Cr content, producing final weight changes of −40 mg/cm2 to −10 mg/cm2 for 0% Cr alloys and −2 mg/cm2 to +1 mg/cm2 for 5% Cr alloys. Accordingly, a multiple linear regression fit yielded an equation showing a strong positive Cr effect and lesser negative effects of Co and Mo. The results for 5% Cr alloys compare well to −1 mg/cm2, and +0.5 mg/cm2 for Rene′ N4 and Rene′ N5 (or Rene′ N6, respectively. Scale phases commonly identified were Al2O3, NiAl2O4, NiTa2O6, and NiO, with (Ni,CoMoO4 found only on the least resistant alloys having 0% Cr and 12% Mo. Scale microstructures were complex and reflected variations in the regional spallation history. Large faceted NiO grains and fine NiTa2O6 particles distributed along NiAl2O4 grain boundaries were typical distinctive features. NiMoO4 formation, decomposition, and volatility occurred for a few high Mo compositions. A creep, density, phase stability, and oxidation balanced 5% Cr, 10% Co, 7% Mo, and 3% Re alloy was selected to be taken forward for more extensive evaluations in single crystal form.

  8. Surface, Nanomechanical, and Optical Properties of Mo-Doped GeGaAs Thin Film Deposited by Thermionic Vacuum Arc

    Science.gov (United States)

    Pat, Suat; Şenay, Volkan; Özen, Soner; Korkmaz, Şadan

    2016-01-01

    Mo-doped and undoped GeGaAs layers have been deposited by the thermionic vacuum arc (TVA) method, an alternative, fast plasma deposition technique. The thicknesses of the deposited layers were identical. The surface, mechanical, and optical properties of the deposited layers were studied to determine the influence of Mo doping on GeGaAs. The transparency of GeGaAs was shifted towards the near-infrared region by Mo doping. Bandgap values shifted by approximately 0.3 eV. In other words, the bandgap value of Mo-doped GeGaAs was nearly equal to that of GaAs materials. The average roughness and grain size of the Mo-doped material were smaller than for the GeGaAs layer. The particle distributions of the Mo-doped and undoped GeGaAs were almost perfect Gaussians. However, the mean height of the Mo-doped GeGaAs grains was six times that for undoped GeGaAs. The surface was homogeneous. The Mo-doped layer showed greater absorbance than the GeGaAs material. The produced Mo-doped sample showed hybrid properties.

  9. Segregation to grain boundaries in nimonic PE16 superalloy

    International Nuclear Information System (INIS)

    Nettleship, D.J.; Wild, R.K.

    1990-01-01

    Nimonic PE16 alloy is a nickel-based superalloy containing 34 wt.% iron and 16wt.% chromium with additions of molybdenum, titanium and aluminium. It is used in the fuel assembly of the UK advanced gas-cooled reactors (AGR). This component supports significant loads in service and its mechanical integrity is therefore of paramount importance. Mechanical properties may be influenced by the grain size and grain boundary composition, both of which can themselves alter during service. Scanning Auger microscopy is a well-established method for investigating grain boundaries, and has now been applied to the study of PE16. In order to expose PE16 grain boundary surfaces it is necessary to hydrogen charge samples and fracture by pulling in tension at a slow strain rate within the ultra-high vacuum chamber of the Auger microprobe. A series of casts of nimonic PE16 alloy that have received a range of thermal ageing treatments have been fractured in an intergranular manner and the grain boundary composition determined. Segregation of trace and minority elements, particularly Mo and P, has been detected at grain boundaries. Significant variations between different as-manufactured casts were observed, whilst ageing brought about the growth of chromium-rich particles on the grain boundaries. Ductile fracture in PE16 followed a path through Ti(C, N) particles. Many of these particles incorporated large amounts of sulphur. (author)

  10. Shear localization and microstructure in coarse grained beta titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bingfeng, E-mail: biw009@ucsd.edu [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan (China); School of Materials Science and Engineering, Central South University, Changsha, Hunan (China); Department of Mechanical and Aerospace Engineering, University of California, San Diego, United States of America (United States); Key Lab of Nonferrous Materials, Ministry of Education, Central South University, Changsha, Hunan (China); Wang, Xiaoyan [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan (China); School of Materials Science and Engineering, Central South University, Changsha, Hunan (China); Li, Zezhou [Department of Mechanical and Aerospace Engineering, University of California, San Diego, United States of America (United States); Ma, Rui [School of Materials Science and Engineering, Central South University, Changsha, Hunan (China); Zhao, Shiteng [Department of Mechanical and Aerospace Engineering, University of California, San Diego, United States of America (United States); Xie, Fangyu [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan (China); School of Materials Science and Engineering, Central South University, Changsha, Hunan (China); Zhang, Xiaoyong [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan (China)

    2016-01-15

    Adiabatic shear localization plays an important role in the deformation and failure of the coarse grained beta titanium alloy Ti-5 Al-5 Mo-5 V-1 Cr-1 Fe with grain size about 1 mm at high strain rate deformation. Hat shaped specimens with different nominal shear strains are used to induce the formation of shear bands under the controlled shock-loading experiments. The true stress in the specimens can reach about 1040 MPa where the strain is about 1.83. The whole shear localization process lasts about 35 μs. The microstructures within the shear band are investigated by optical microscopy, scanning electron microscopy / electron backscatter diffraction, and transmission electron microscopy. The results show that the width of the shear bands decreases with increasing nominal shear strain, and the grains in the transition region near the shear band are elongated along the shear band, and the core of the shear band consists of the ultrafine deformed grains with width of 0.1 μm and heavy dislocations. With the aims of accommodating the imposed shear strain and maintaining neighboring grain compatibility, the grain subdivision continues to take place within the band. A fiber texture is formed in the core of the shear band. The calculated temperature rise in the shear band can reach about 722 K. Dynamic recovery is responsible for the formation of the microstructure in coarse grained beta titanium alloy.

  11. grain-filling, chlorophyll content in relation with grain yield

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    number of fertile tillers nor number of grains per m². Grain weight is, however, reduced (Hochman,. 1982) due to a shortening of the grain filling period resulting from accelerated senescence. A long duration of grain filling is often an indicator of photosynthetic activity optimum, but a high velocity of filling is indicative of water.

  12. Processing, Microstructure and Creep Behavior of Mo-Si-B-Based Intermetallic Alloys for Very High Temperature Structural Applications

    Energy Technology Data Exchange (ETDEWEB)

    Vijay Vasudevan

    2008-03-31

    This research project is concerned with developing a fundamental understanding of the effects of processing and microstructure on the creep behavior of refractory intermetallic alloys based on the Mo-Si-B system. In the first part of this project, the compression creep behavior of a Mo-8.9Si-7.71B (in at.%) alloy, at 1100 and 1200 C was studied, whereas in the second part of the project, the constant strain rate compression behavior at 1200, 1300 and 1400 C of a nominally Mo-20Si-10B (in at.%) alloy, processed such as to yield five different {alpha}-Mo volume fractions ranging from 5 to 46%, was studied. In order to determine the deformation and damage mechanisms and rationalize the creep/high temperature deformation data and parameters, the microstructure of both undeformed and deformed samples was characterized in detail using x-ray diffraction, scanning electron microscopy (SEM) with back scattered electron imaging (BSE) and energy dispersive x-ray spectroscopy (EDS), electron back scattered diffraction (EBSD)/orientation electron microscopy in the SEM and transmission electron microscopy (TEM). The microstructure of both alloys was three-phase, being composed of {alpha}-Mo, Mo{sub 3}Si and T2-Mo{sub 5}SiB{sub 2} phases. The values of stress exponents and activation energies, and their dependence on microstructure were determined. The data suggested the operation of both dislocation as well as diffusional mechanisms, depending on alloy, test temperature, stress level and microstructure. Microstructural observations of post-crept/deformed samples indicated the presence of many voids in the {alpha}-Mo grains and few cracks in the intermetallic particles and along their interfaces with the {alpha}-Mo matrix. TEM observations revealed the presence of recrystallized {alpha}-Mo grains and sub-grain boundaries composed of dislocation arrays within the grains (in Mo-8.9Si-7.71B) or fine sub-grains with a high density of b = 1/2<111> dislocations (in Mo-20Si-10B), which

  13. Radiation disinfestation of grain

    International Nuclear Information System (INIS)

    1962-01-01

    A panel was convened by the International Atomic Energy Agency to consider ways of applying radiation to grain handling and insect control, and to make recommendations on the advisability and nature of any future action in this field. Among other subjects, the panel discussed the use of electron accelerators and gamma radiation for grain disinfestation as well as problems of radiation entomology and wholesomeness of irradiated grain. After reviewing the present state of knowledge regarding radiation disinfestation of grain, the experts agreed that pilot plant operations be initiated as soon as practicable in order to evaluate the use of irradiation plants under practical conditions in their entomological, engineering and economic aspects. They recommended that research effort be directed towards solving certain fundamental problems related to the proposed pilot plant projects; such as rapid methods for differentiation between sterile insects and normal ones; study of the metabolism of irradiated immature stages of insects in relation to the heating of treated grain; research into possible induction of radiation resistance; irradiation susceptibility of insects which show resistance to conventional insecticides; and study of methods of sensitizing insects to irradiation damage. It was also pointed out that the distribution of irradiated food for human consumption was controlled in most countries under present legislative procedures, and no country had yet approved radiation treatment of cereals. The experts recommended that countries in a position to submit evidence to their appropriate authorities regarding the wholesomeness of irradiated cereals should be encouraged to do so as soon as possible. Regarding the engineering aspects of irradiation pilot plant projects, the experts noted that the process could be automated and operated safely. Electron accelerators and cobalt sources could be used for all the throughput rates utilized in most conventional grain

  14. Computerized radioautographic grain counting

    International Nuclear Information System (INIS)

    McKanna, J.A.; Casagrande, V.A.

    1985-01-01

    In recent years, radiolabeling techniques have become fundamental assays in physiology and biochemistry experiments. They also have assumed increasingly important roles in morphologic studies. Characteristically, radioautographic analysis of structure has been qualitative rather than quantitative, however, microcomputers have opened the door to several methods for quantifying grain counts and density. The overall goal of this chapter is to describe grain counting using the Bioquant, an image analysis package based originally on the Apple II+, and now available for several popular microcomputers. The authors discuss their image analysis procedures by applying them to a study of development in the central nervous system

  15. Study and methods of analysis of mechanically alloyed Cu-Mo powders

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C. [Departamento de Ingenieria Metalurgica, Universidad de Santiago de Chile, USACH, Av. Lib. Bernardo O' Higgins, 3363 Santiago (Chile)], E-mail: ceaguilar@uda.cl; Ordonez, S. [Departamento de Ingenieria Metalurgica, Universidad de Santiago de Chile, USACH, Av. Lib. Bernardo O' Higgins, 3363 Santiago (Chile); Marin, J. [Comision Chilena de Energia Nuclear, CCHEN, Amunategui 95, Santiago (Chile); Castro, F. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa, CEIT, Po de Manuel de Lardizabal, 15 (Bo de Ibaeta), 20.018 Donostia, San Sebastian (Spain); Martinez, V. [Departamento de Ingenieria Metalurgica, Universidad de Santiago de Chile, USACH, Av. Lib. Bernardo O' Higgins, 3363 Santiago (Chile)

    2007-08-25

    The microstructural evolution during mechanical alloying of Cu and Mo was studied. The aim of this work is to study the effect of the milling time on the formation of the solid solution of molybdenum in copper, employing variable amounts of Mo (1 and 8 at.%). The milling was performed under an inert argon atmosphere in a SPEX 8000D mill. Milling times of 4, 8, 25, 50, 75 and 100 h were used keeping a constant ball to powder ratio of 10-1. The effects of milling parameters such as milling time and composition on the synthesis and structure of Cu-Mo powders were investigated using XRD, nanohardness, differential scanning calorimetry (DSC) and TEM. The results show that the grain size and particle size of powders decrease with increasing milling time. Grain size in samples with 8 at.% Mo approached a minimum value of 20 nm after 50 h, and in samples with 1 at.% Mo, 30 nm after 75 h of milling. Nanohardness shows a maximum about 4 GPa for the alloy with 8 at.% of Mo and 100 h of milling. The measured crystallite size by TEM is in good agreement with the value calculated by XRD. Thermal analyses (DSC) showed the temperature intervals where the dynamic recrystallization would take place. According to these results this phenomenon would happen near 350 deg. C.

  16. Simulating grain size estimation

    Czech Academy of Sciences Publication Activity Database

    Saxl, Ivan; Sülleiová, K.; Ponížil, P.

    2001-01-01

    Roč. 39, č. 6 (2001), s. 396-409 ISSN 0023-432X R&D Projects: GA ČR GA201/99/0269 Keywords : grain size estimation% ASTM standards%Voronoi tessellations Subject RIV: BE - Theoretical Physics Impact factor: 0.343, year: 2001

  17. Interstellar grain surface chemistry

    International Nuclear Information System (INIS)

    Tielens, A.G.G.M.

    1989-01-01

    Theoretical calculations, laboratory studies, and observations of interstellar icy grain mantles are reviewed. The emphasis is on recent ground-based observations of the interstellar 2167 cm -1 (4.67μm) band and air-borne studies of the interstellar 1665 and 1460 cm -1 (6.0 and 6.85μm) bands. From a comparison with laboratory studies it is concluded that interstellar icy gain mantles consist mainly of H 2 O, CH 3 OH and CO in an approximate ratio of 100:50:5. Traces of other molecules have also been detected. Evidence for the presence of a separate, more inert, grain mantle component, perhaps consisting mainly of solid CO, will also be presented. Theoretical calculations of the composition of interstellar icy gain mantles are confronted with observational data and the shortcomings of the models are pointed out. Finally, the evolution of icy grain mantles under UV irradiation and their possible interrelationship with an organic grain component observed in the diffuse interstellar medium are discussed

  18. 6 Grain Yield

    African Journals Online (AJOL)

    have stable, not too short crop duration with ... Ndiaye is located in the. Costal Delta region of Senegal. The climate of the Delta is characterized by a wet season from July to October with approximately. 200 mm of ..... Analysis of variance of the effect of site and season on maturity, grain yield and plant height of 16 rice.

  19. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  20. Preparation of MoB and MoB-MoSi2 composites by combustion synthesis in SHS mode

    International Nuclear Information System (INIS)

    Yeh, C.L.; Hsu, W.S.

    2007-01-01

    Combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) was carried out in the Mo-B and Mo-B-Si systems for the preparation of molybdenum boride MoB and the composite of MoB-MoSi 2 from elemental powder compacts. Under a preheating temperature above 150 deg. C , the reaction of Mo with boron in the sample compact of Mo:B = 1:1 is characterized by a planar combustion front propagating in a self-sustaining and steady manner. As the preheating temperature or sample compaction density increased, combustion temperature was found to increase and the propagation rate of the combustion front was correspondingly enhanced. Moreover, the XRD analysis provides evidence of yielding nearly single-phase α-MoB from the Mo-B sample at equiatomic stoichiometry. In the synthesis of MoB-MoSi 2 composites, the starting stoichiometry of the Mo-B-Si powder compact was varied so as to produce the final composites containing 20-80 mol% MoB. It was also found the increase of flame-front velocity and combustion temperature with increasing MoB content formed in the composite. The composition analysis by XRD shows excellent conversion from the Mo-B-Si powder compact to the MoB-MoSi 2 composite through the SHS reaction; that is, in addition to a small amount of Mo 5 Si 3 , the as-synthesized composite is composed entirely of MoB and MoSi 2

  1. Magnetic field effects on the electrodeposition of CoNiMo alloys

    Science.gov (United States)

    Aaboubi, Omar; Msellak, Khalid

    2017-02-01

    In this work we have examined the influence of applying homogeneous magnetic field (MF) up to 1.2T, on Cobalt- Nickel-Molybdenum (CoNiMo) alloys electrodeposition from citric bath. The surface morphology, chemical composition and the crystallographic texture has been investigated by X-ray diffraction (XRD), X-ray composition mapping and scanning electron microscopy (SEM) images. The mass transport behaviour during the electrodeposition process has been examined through the polarization curves and electrochemical impedance methods. As expected, under MF control an enhancement in the mass transport rate was observed leading to grains refinement and homogeneous distribution of the Co, Mo and Ni atoms in the obtained CoNiMo films. These findings highlight the synergistic combination of Ni, Co and Mo by promoting the MHD convection due to the Lorentz force acting during the Ni(II) and Co(II) ions reduction.

  2. Carbides in Nodular Cast Iron with Cr and Mo

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2007-07-01

    Full Text Available In these paper results of elements microsegregation in carbidic nodular cast iron have been presented. A cooling rate in the centre of the cross-section and on the surface of casting and change of moulding sand temperature during casting crystallization and its self-cooling have been investigated. TDA curves have been registered. The linear distribution of elements concentration in an eutectic grain, primary and secondary carbides have been made. It was found, that there are two kinds of carbides: Cr and Mo enriched. A probable composition of primary and secondary carbides have been presented.

  3. Biaxial magnetic grain alignment

    International Nuclear Information System (INIS)

    Staines, M.; Genoud, J.-Y.; Mawdsley, A.; Manojlovic, V.

    2000-01-01

    Full text: We describe a dynamic magnetic grain alignment technique which can be used to produce YBCO thick films with a high degree of biaxial texture. The technique is, however, generally applicable to preparing ceramics or composite materials from granular materials with orthorhombic or lower crystal symmetry and is therefore not restricted to superconducting applications. Because magnetic alignment is a bulk effect, textured substrates are not required, unlike epitaxial coated tape processes such as RABiTS. We have used the technique to produce thick films of Y-247 on untextured silver substrates. After processing to Y-123 the films show a clear enhancement of critical current density relative to identically prepared untextured or uniaxially textured samples. We describe procedures for preparing materials using magnetic biaxial grain alignment with the emphasis on alignment in epoxy, which can give extremely high texture. X-ray rocking curves with FWHM of as little as 1-2 degrees have been measured

  4. Grain alcohol study: summary

    Energy Technology Data Exchange (ETDEWEB)

    The study has concentrated upon a detailed examination of all considerations involved in the production, use, and marketing of ethyl alcohol (ethanol) as produced from the fermentation of agricultural grains. Each parameter was examined in the light of current energy markets and trends; new sources and technological, and processes for fermentation, the capability of the agricultural industry to support fermentation demand; the optimizaton of value of agricultural crops; and the efficiencies of combining related industries. Ahydrous (200 proof) ethanol makes an excellent blending component for all present automotive fuels and an excellent octane additive for unleaded fuels in proportions up to 35% without requiring modifications to current engines. There is no difference between ethanol produced by fermentation and ethanol produced synthetically from petroleum. The decision to produce ethanol one way or the other is purely economic. The agricultural industry can support a major expansion in the fermentation industry. The residue (distillers grains) from the fermentation of corn for ethanol is an excellent and economical feed for livestock and poultry. A reliable supply of distillers grain can assist in making the large beef feedlot operations more economically viable. The source materials, fuels, products and by-products of an ethanol plant, beef feedlot, gas biodigester plant, municipal waste recovery plant and a steam generated electrical plant are interrelated and mutually beneficial for energy efficiencies and economic gains when co-located. The study concludes that the establishment of such agricultural- environment industrial energy complexes, would provide a broad range of significant benefits to Indiana.

  5. Grain alcohol study: summary

    Energy Technology Data Exchange (ETDEWEB)

    The study has concentrated upon a detailed examination of all considerations involved in the production, use, and marketing of ethyl alcohol (Ethanol) as produced from the fermentation of agricultural grains. Each parameter was examined in the light of current energy markets and trends; new sources and technological, and processes for fermentation, the capability of the agricultural industry to support fermentaton demand; the optimization of value of agricultureal crops; and the efficiencies of combining related industries. Anhydrous (200 proof) ethanol makes an excellent blending component for all present automotive fuels and an excellent octane additive for unleaded fuels in proportions up to 35% without requiring modifications to current engines. There is no difference between ethanol produced by fermentation and ethanol produced synthetically from petroleum. The decision to produce ethanol one way or the other is purely economic. The agricultural industry can support a major expansion in the fermentation industry. The residue (distillers grains) from the fermentation of corn for ethanol is an excellent and economical feed for livestock and poultry. A reliable supply of distillers grains can assist in making the large beef feedlot operations more economically viable. The source materials, fuels, products and by-products of an ethanol plant, beef feedlot, gas biodigester plant, municipal waste recovery plant and a steam generated electrical plant are interrelated and mutually beneficial for energy efficiencies and economic gains when co-located. The study concludes that the establishment of such agricultural-environment industrial energy complexes, would provide a broad range of significant benefits to Indiana.

  6. Grain preservation in SSSR

    International Nuclear Information System (INIS)

    Trisviatski, L.A.

    1973-01-01

    First the importance of cereals collected in the S.S.S.R., the reason why the government had to put in practice a storage chain, composed of large capacity store houses (200 000 metric tonnes, or more) is reminded. When climatic conditions result in wet harvested grains, cereals are dried either in state enterprise dryers (32 to 50 tonnes/hour) or in kolkhozes' dryers (2 to 16 tonnes/hour). A new type of drying with recycling, has been developped, economizing 10 to 15 p. 100. Then the possibilities offered by the technique of partial drying of very wet grains are studied and the preservation processes using fresh ventilation, or hot ventilation with drying effect are described. The question of silage of wet grains destined to animal consumption is then examined as well as preservation by sodium pyrosulfide; the use of propionic acid, little developped in SSSR, is studied now, just as storage with inert gas. The struggle technics against insects, either with chemical agents, or with irradiation are described. Finally the modalities of technicians formation, specialized in preservation, are discussed [fr

  7. Refining As-cast β-Ti Grains Through ZrN Inoculation

    Science.gov (United States)

    Qiu, Dong; Zhang, Duyao; Easton, Mark A.; St John, David H.; Gibson, Mark A.

    2018-03-01

    The columnar-to-equiaxed transition and remarkable refinement of β-Ti grains occur in an as-cast Ti-13Mo alloy when a new grain refiner, ZrN, was inoculated at a nitrogen level as low as 0.4 wt pct. The grain refining effect is attributed to in situ-formed TiN particles that provide active nucleation sites and solute Zr that promotes constitutional supercooling. Reproducible orientation relationships were identified between TiN nucleants and β-Ti matrix, and well explained by the edge-to-edge matching model.

  8. Growth, structure and stability of sputter-deposited MoS2 thin films

    Directory of Open Access Journals (Sweden)

    Reinhard Kaindl

    2017-05-01

    Full Text Available Molybdenum disulphide (MoS2 thin films have received increasing interest as device-active layers in low-dimensional electronics and also as novel catalysts in electrochemical processes such as the hydrogen evolution reaction (HER in electrochemical water splitting. For both types of applications, industrially scalable fabrication methods with good control over the MoS2 film properties are crucial. Here, we investigate scalable physical vapour deposition (PVD of MoS2 films by magnetron sputtering. MoS2 films with thicknesses from ≈10 to ≈1000 nm were deposited on SiO2/Si and reticulated vitreous carbon (RVC substrates. Samples deposited at room temperature (RT and at 400 °C were compared. The deposited MoS2 was characterized by macro- and microscopic X-ray, electron beam and light scattering, scanning and spectroscopic methods as well as electrical device characterization. We find that room-temperature-deposited MoS2 films are amorphous, of smooth surface morphology and easily degraded upon moderate laser-induced annealing in ambient conditions. In contrast, films deposited at 400 °C are nano-crystalline, show a nano-grained surface morphology and are comparatively stable against laser-induced degradation. Interestingly, results from electrical transport measurements indicate an unexpected metallic-like conduction character of the studied PVD MoS2 films, independent of deposition temperature. Possible reasons for these unusual electrical properties of our PVD MoS2 thin films are discussed. A potential application for such conductive nanostructured MoS2 films could be as catalytically active electrodes in (photo-electrocatalysis and initial electrochemical measurements suggest directions for future work on our PVD MoS2 films.

  9. Storing Peanuts in Grain Bags

    Science.gov (United States)

    A study was executed to determine the potential of storing farmers stock peanuts and shelled peanuts for crushing in hermetically sealed grain bags. The objectives of the study were to evaluate equipment for loading and unloading the grain bags, the capacity of the grain bags, and the changes in qu...

  10. 99Mo Yield Using Large Sample Mass of MoO3 for Sustainable Production of 99Mo

    Science.gov (United States)

    Tsukada, Kazuaki; Nagai, Yasuki; Hashimoto, Kazuyuki; Kawabata, Masako; Minato, Futoshi; Saeki, Hideya; Motoishi, Shoji; Itoh, Masatoshi

    2018-04-01

    A neutron source from the C(d,n) reaction has the unique capability of producing medical radioisotopes such as 99Mo with a minimum level of radioactive waste. Precise data on the neutron flux are crucial to determine the best conditions for obtaining the maximum yield of 99Mo. The measured yield of 99Mo produced by the 100Mo(n,2n)99Mo reaction from a large sample mass of MoO3 agrees well with the numerical result estimated with the latest neutron data, which are a factor of two larger than the other existing data. This result establishes an important finding for the domestic production of 99Mo: approximately 50% of the demand for 99Mo in Japan could be met using a 100 g 100MoO3 sample mass with a single accelerator of 40 MeV, 2 mA deuteron beams.

  11. The effect of molybdenum on the grain boundary segregation of phosphorus in steel

    International Nuclear Information System (INIS)

    Moller, R.; Brenner, S.S.; Grabke, A.J.

    1986-01-01

    The beneficial effect of molybdenum on the temper embrittlement of steels is well known but has not yet been satisfactorily explained. Yu and McMahon suggested a strong interaction between molybdenum and phosphorus to form Mo-P clusters which decrease the concentration of phosphorus in the matrix and consequently the amount segregated to grain boundaries. Such clusters have as yet not been observed but this may have been owing to the insufficient resolution of conventional analytical methods. However, since no scavenging of phosphorus was observed in carbon-free Fe-Mo-P alloys, i.e. Mo alone did not affect the grain boundary concentration of phosphorus, it is improbable that the Mo-P cluster formation mechanisms can be operative. Instead, it is more likely that a requisite for the scavenging of phosphorus is the formation of Mo carbides in the steel. This work was undertaken to determine the distribution of phosphorus in two similar Fe-Mo-P alloys, one of which contained carbon while the other was carbon-free. The emphasis of the study was to determine the interaction of phosphorus with molybdenum and molybdenum carbides in the steel. Field-ion microscopy combined with atom probe microanalysis was used for this purpose. The atom-by-atom sampling method and the near-atomic spatial resolution of the FIM/atom probe make this instrument ideally suited for this type of investigations

  12. Optical and structural properties of Mo-doped NiTiO3 materials synthesized via modified Pechini methods

    Science.gov (United States)

    Pham, Thanh-Truc; Kang, Sung Gu; Shin, Eun Woo

    2017-07-01

    In this study, molybdenum (Mo)-doped nickel titanate (NiTiO3) materials were successfully synthesized as a function of Mo content through a modified Pechini method followed by a solvothermal treatment process. Various characterization methods were employed to investigate the optical and structural properties of the materials. XRD patterns clearly showed that the NiTiO3 structure maintained a single phase with no observed crystalline structure transformations, even after the addition of 10 wt.% Mo. In the Raman spectra and XRD patterns, peak positions shifted with a change in Mo content, confirming that the NiTiO3 lattice was doped with Mo. On the other hand, Mo doping of NiTiO3 materials changed their optical properties. DRS-UV demonstrated that the addition of Mo increased photon absorption within the UV region. Relaxation processes were inhibited by Mo doping, which was evident in the PL spectra. Structural properties of the prepared materials were studied via FE-SEM and HR-TEM. The measured surface area increased proportionally with Mo content due to a reduction in grain size of the materials.

  13. Effect of Boron on Microstructure and Microhardness Properties of Mo-Si-B Based Coatings Produced Via TIG Process

    Directory of Open Access Journals (Sweden)

    Islak S.

    2016-09-01

    Full Text Available In this study, Mo-Si-B based coatings were produced using tungsten inert gas (TIG process on the medium carbon steel because the physical, chemical, and mechanical properties of these alloys are particularly favourable for high-temperature structural applications. It is aimed to investigate of microstructure and microhardness properties of Mo-Si-B based coatings. Optical microscopy (OM, X-ray diffraction (XRD and scanning electron microscopy (SEM were used to characterize the microstructures of Mo-Si-B based coatings. The XRD results showed that microstructure of Mo–Si–B coating consists of α-Mo, α-Fe, Mo2B, Mo3Si and Mo5SiB2 phases. It was reported that the grains in the microstructure were finer with increasing amounts of boron which caused to occur phase precipitations in the grain boundary. Besides, the average microhardness of coatings changed between 735 HV0.3 and 1140 HV0.3 depending on boron content.

  14. Mechanically activated synthesis of nanocrystalline ternary carbide Fe{sub 3}Mo{sub 3}C

    Energy Technology Data Exchange (ETDEWEB)

    Zakeri, M. [Materials Science Department, Islamic Azad University (Saveh branch), Saveh (Iran, Islamic Republic of)], E-mail: M_zakeri@iau-saveh.ac.ir; Rahimipour, M.R. [Ceramic Department, Materials and Energy Research Center, Tehran (Iran, Islamic Republic of); Khanmohammadian, A. [Materials Science Department, Islamic Azad University (Saveh branch), Saveh (Iran, Islamic Republic of)

    2008-09-25

    In this investigation, Fe{sub 3}Mo{sub 3}C ternary carbide was synthesized from the elemental powders of 3Mo/3Fe/C by mechanical milling and subsequent heat treatment. Structural and morphological evolutions of powders were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results showed that no phase transformation occurs during milling. A nanostructure Mo (Fe) solid solution obtained after 30 h of milling. With increasing milling time to 70 h no change takes place except grain size reduction to 9 nm and strain enhancement to 0.86%. Milled powders have spheroid shape and very narrow size distribution about 2 {mu}m at the end of milling. Fe{sub 3}Mo{sub 3}C was synthesized during annealing of 70 h milled sample at 700 deg. C. Undesired phases of MoOC and Fe{sub 2}C form at 1100 deg. C. No transformation takes place during annealing of 10 h milled sample at 700 deg. C. Mean grain size and strain get to 69 nm and 0.23% respectively with annealing of 70 h milled sample at 1100 deg. C.

  15. Dipole strength distribution below the giant dipole resonance in {sup 92}Mo, {sup 98}Mo and {sup 100}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Rusev, G.Y.

    2006-07-01

    Investigations of the dipole-strength distributions in {sup 92}Mo, {sup 98}Mo and {sup 100}Mo were carried out by means of the method of nuclear resonance fluorescence. The low-lying excitations in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been studied in photon-scattering experiments at an electron energy of 6 MeV at the ELBE accelerator and at electron energies from 3.2 to 3.8 MeV at the Dynamitron accelerator. Five levels were observed in {sup 92}Mo. Five levels in {sup 98}Mo and 14 in {sup 100}Mo were identified for the first time in the energy range from 2 to 4 MeV. Dipole-strength distributions up to the neutron-separation energies in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been investigated at the ELBE accelerator. Because of the possible observation of transitions in the neighboring nuclei produced via ({gamma},n) reaction, additional measurements at electron energies of 8.4 and 7.8 MeV, below the neutron-separation energy, were performed on {sup 98}Mo and {sup 100}Mo, respectively. The number of transitions assigned to {sup 92}Mo, {sup 98}Mo and {sup 100}Mo is 340, 485 and 499, respectively, the main part of them being dipole transitions. Statistical properties of the observed transitions are obtained. The continuum contains the ground-state transitions as well as the branching transitions to the low-lying levels and the subsequent deexcitations of these levels. (orig.)

  16. Mo(ve)ment-methodology

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Christian Celosse-Andersen, Martin

    2017-01-01

    This paper describes the theoretical basis and development of a moment-movement research methodology, based on an integration of critical psychological practice research and critical ethnographic social practice theory. The paper illustrates how the mo(ve)ment methodology was applied in a study...... of major identity formation and gang exit processes, done together with a former biker gang member, Martin, becoming a research apprentice and more academically reflective, while moving beyond gang involvement. The paper empirically exemplifies the mo(ve)ment methodology presenting and analyzing one...

  17. Alternative grains in nutrition

    Directory of Open Access Journals (Sweden)

    Jevcsák Sz.

    2016-12-01

    Full Text Available Many people suffer from gluten sensitivity or gluten intolerance. They have to avoid or limit their gluten intake. Sorghum and millet are gluten-free cereals, wherefore persons with gluten sensitivity or gluten intolerance could consume them. Moreover, they have a lot of positive effects due to their phenolic compounds as phenol acid or flavonoid. Antioxidant activity in sorghum is especially high in comparison with other cereals. Our aim was to compare literature data about the chemical compositions of sorghum and millet with other grains.

  18. Effect of Mo on Microstructures and Wear Properties of In Situ Synthesized Ti(C,N)/Ni-Based Composite Coatings by Laser Cladding.

    Science.gov (United States)

    Wu, Fan; Chen, Tao; Wang, Haojun; Liu, Defu

    2017-09-06

    Using Ni60 alloy, C, TiN and Mo mixed powders as the precursor materials, in situ synthesized Ti(C,N) particles reinforcing Ni-based composite coatings are produced on Ti6Al4V alloys by laser cladding. Phase constituents, microstructures and wear properties of the composite coatings with 0 wt % Mo, 4 wt % Mo and 8 wt % Mo additions are studied comparatively. Results indicate that Ti(C,N) is formed by the in situ metallurgical reaction, the (Ti,Mo)(C,N) rim phase surrounding the Ti(C,N) ceramic particle is synthesized with the addition of Mo, and the increase of Mo content is beneficial to improve the wear properties of the cladding coatings. Because of the effect of Mo, the grains are remarkably refined and a unique core-rim structure that is uniformly dispersed in the matrix appears; meanwhile, the composite coatings with Mo addition exhibit high hardness and excellent wear resistance due to the comprehensive action of dispersion strengthening, fine grain strengthening and solid solution strengthening.

  19. Effect of bimodal harmonic structure design on the deformation behaviour and mechanical properties of Co-Cr-Mo alloy.

    Science.gov (United States)

    Vajpai, Sanjay Kumar; Sawangrat, Choncharoen; Yamaguchi, Osamu; Ciuca, Octav Paul; Ameyama, Kei

    2016-01-01

    In the present work, Co-Cr-Mo alloy compacts with a unique bimodal microstructural design, harmonic structure design, were successfully prepared via a powder metallurgy route consisting of controlled mechanical milling of pre-alloyed powders followed by spark plasma sintering. The harmonic structured Co-Cr-Mo alloy with bimodal grain size distribution exhibited relatively higher strength together with higher ductility as compared to the coarse-grained specimens. The harmonic Co-Cr-Mo alloy exhibited a very complex deformation behavior wherein it was found that the higher strength and the high retained ductility are derived from fine-grained shell and coarse-grained core regions, respectively. Finally, it was observed that the peculiar spatial/topological arrangement of stronger fine-grained and ductile coarse-grained regions in the harmonic structure promotes uniformity of strain distribution, leading to improved mechanical properties by suppressing the localized plastic deformation during straining. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Irradiated microstructure of U-10Mo monolithic fuel plate at very high fission density

    Energy Technology Data Exchange (ETDEWEB)

    Gan, J.; Miller, B. D.; Keiser, D. D.; Jue, J. F.; Madden, J. W.; Robinson, A. B.; Ozaltun, H.; Moore, G.; Meyer, M. K.

    2017-08-01

    Monolithic U-10Mo alloy fuel plates with Al-6061 cladding are being developed for use in research and test reactors as low enrichment fuel (< 20% U-235 enrichment) as a result of its high uranium loading capacity compared to that of U-7Mo dispersion fuel. These fuel plates contain a Zr diffusion barrier between the U-10Mo fuel and Al-6061 cladding that suppresses the interaction between the U-Mo fuel foil and Al alloy cladding that is known to be problematic under irradiation. This paper discusses the TEM results of the U-10Mo/Zr/Al6061 monolithic fuel plate (Plate ID: L1P09T, ~ 59% U-235 enrichment) irradiated in Advanced Test Reactor at Idaho National Laboratory as part of RERTR-9B irradiation campaign with an unprecedented high local fission density of 9.8E+21 fissions/cm3. The calculated fuel foil centerline temperature at the beginning of life and the end of life is 141 and 194 C, respectively. A total of 5 TEM lamellas were prepared using focus ion beam lift-out technique. The estimated U-Mo fuel swelling, based on the fuel foil thickness change from SEM, is approximately 76%. Large bubbles (> 1 µm) are distributed evenly in U-Mo and interlink of these bubbles is evident. The average size of subdivided grains at this fission density appears similar to that at 5.2E+21 fissions/cm3. The measured average Mo and Zr content in the fuel matrix is ~ 30 at% and ~ 7 at%, respectively, in general agreement with the calculated Mo and Zr from fission density.

  1. Germinated grains: a superior whole grain functional food?

    Science.gov (United States)

    Nelson, Kristina; Stojanovska, Lily; Vasiljevic, Todor; Mathai, Michael

    2013-06-01

    Grains are global dietary staples that when consumed in whole grain form, offer considerable health benefits compared with milled grain foods, including reduced body weight gain and reduced cardiovascular and diabetes risks. Dietary patterns, functional foods, and other lifestyle factors play a fundamental role in the development and management of epidemic lifestyle diseases that share risks of developing adverse metabolic outcomes, including hyperglycaemia, hypertension, dyslipidaemia, oxidative stress, and inflammation. Whole grains provide energy, nutrients, fibres, and bioactive compounds that may synergistically contribute to their protective effects. Despite their benefits, the intake of grains appears to be lower than recommended in many countries. Of emerging interest is the application of germination processes, which may significantly enhance the nutritional and bioactive content of grains, as well as improve palatability. Enhancing grain foods in a natural way using germination techniques may therefore offer a practical, natural, dietary intervention to increase the health benefits and acceptability of whole grains, with potentially widespread effects across populations in attenuating adverse lifestyle disease outcomes. Continuing to build on the growing body of in-vitro studies requires substantiation with extended in-vivo trials so that we may further develop our understanding of the potential of germinated grains as a functional food.

  2. K2MoO4-CaMoO4-BaMoO4 system

    International Nuclear Information System (INIS)

    Gasanaliev, A.M.; Trunin, A.S.; Dibirov, M.A.

    1979-01-01

    The liquidus of the K 2 MoO 4 -CaMoO 4 -BaMoO 4 ternary system has been studied by differential thermal (DTA) and by visual polythermal (VPT) analyses. The compositions and temperatures of non-variant points have been determined, the borders between the crystallizing phase regions being found

  3. Optimization of the Processing of Mo Disks

    Energy Technology Data Exchange (ETDEWEB)

    Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States); Rotsch, David A. [Argonne National Lab. (ANL), Argonne, IL (United States); Stepinski, Dominique [Argonne National Lab. (ANL), Argonne, IL (United States); Makarashvili, Vakhtang [Argonne National Lab. (ANL), Argonne, IL (United States); Harvey, James [NorthStar Medical Technologies, LLC, Madison, WI (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    The objective of this work is to decrease the processing time for irradiated disks of enriched Mo for the production of 99Mo. Results are given for the dissolution of nonirradiated Mo disks, optimization of the process for large-scale dissolution of sintered disks, optimization of the removal of the main side products (Zr and Nb) from dissolved targets, and dissolution of irradiated Mo disks.

  4. How the sedimentary Re/Mo ratio and Tl enrichments trace past and present opaline productivity

    Science.gov (United States)

    Böning, Philipp; Brumsack, Hans-Jürgen

    2010-05-01

    Here, we critically examine how the trace metals Mo, Re and (the rather enigmatic) Tl may serve as indicators of productivity events, as shown for Late Quaternary organic/opal-rich, fast accumulating sediments in upwelling areas off Peru and Namibia. In all Peruvian samples, Mo and Re are highly enriched. The ultimate trapping mechanism for Mo in the sediments is H2S availability, i.e., the intensity of sulfate reduction. Rhenium, by contrast, seems to accumulate via diffusion across the sediment-water interface according to the extent of reducing conditions (Böning et al., 2004; 2009). Opal was determined in Peruvian surface samples (0-1 cm, 16 stations, 85 to 1400 m water depth) and in a long Pleistocene core by Wolf (2002). Interestingly, low Re/Mo ratios (close to and below the sea water value, i. e. ≤ 2 * 10-4) as well as Tl are significantly correlated with opal contents in samples from the surface and the long core (r2 >0.8). Our data clearly show that such low Re/Mo ratios are typical of fine-grained sediments rich in fresh organic matter (no coarse material, no phosphorites). Off Namibia opal-rich sediments show high contents in Re and Mo and very low Re/Mo ratios, averaging 0.5 * 10-4. In short and long cores off Namibia and Peru, where Re/Mo is ≤ 1 * 10-4, Tl seems exclusively associated with opal (as seen in a significant correlation of Tl/Al with Si/Al; r2 >0.8). How do we explain such low Re/Mo ratios? Even if the trapping mechanisms are different for Mo and Re, Crusius et al's. (1996) Re-Mo relationship is quite useful. These authors proposed that a Re/Mo ratio close to the seawater ratio (0.8 * 10-4) reflect the quantitative removal of both Re and Mo from solution. But the Re/Mo ratio below the seawater ratio cannot be explained by diffusion of both elements and quantitative enrichment in the sediments. Indeed, the diffusion of Re and Mo is limited off Namibia and Peru given the enormous biogenic particle rain. Hence, we propose an additional

  5. Pseudo-Capacitors: SPPS Deposition and Electrochemical Analysis of α-MoO3 and Mo2N Coatings

    Science.gov (United States)

    Golozar, Mehdi; Chien, Ken; Lian, Keryn; Coyle, Thomas W.

    2013-06-01

    Solution precursor plasma spraying (SPPS) is a novel thermal spray process in which a solution precursor is injected into the high-temperature zone of a DC-arc plasma jet to allow solvent evaporation from the precursor droplets, solute precipitation, and precipitate pyrolysis prior to substrate impact. This investigation explored the potential of SPPS to fabricate α-MoO3 coatings with fine grain sizes, high porosity levels, and high surface area: characteristics needed for application as pseudo-capacitor electrodes. Since molybdenum nitride has shown a larger electrochemical stability window and higher specific area capacitance, the α-MoO3 deposits were subsequently converted into molybdenum nitride. A multistep heat-treatment procedure resulted in a topotactic phase-transformation mechanism, which retained the high surface area lath-shaped features of the original α-MoO3. The electrochemical behaviors of molybdenum oxide and molybdenum nitride deposits formed under different deposition conditions were studied using cyclic voltammetry to assess the influence of the resulting microstructure on the charge storage behavior and potential for use in pseudo-capacitors.

  6. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  7. Measurement and Estimation of the 99Mo Production Yield by 100Mo(n,2n)99Mo

    Science.gov (United States)

    Minato, Futoshi; Tsukada, Kazuaki; Sato, Nozomi; Watanabe, Satoshi; Saeki, Hideya; Kawabata, Masako; Hashimoto, Shintaro; Nagai, Yasuki

    2017-11-01

    We, for the first time, measured the yield of 99Mo, the mother nuclide of 99mTc used in nuclear medicine diagnostic procedures, produced by the 100Mo(n,2n)99Mo reaction with accelerator neutrons. The neutrons with a continuous energy spectrum from the thermal energy up to about 40 MeV were provided by the C(d,n) reaction with 40 MeV deuteron beams. It was proved that the 99Mo yield agrees with that estimated by using the latest data on neutrons from the C(d,n) reaction and the evaluated cross section of the 100Mo(n,2n)99Mo reaction given in the Japanese Evaluated Nuclear Data Library. On the basis of the agreement, a systematic calculation was carried out to search for an optimum condition that enables us to produce as much 99Mo as possible with a good 99Mo/100Mo value from an economical point of view. The calculated 99Mo yield from a 150 g 100MoO3 sample indicated that about 30% of the demand for 99Mo in Japan can be met with a single accelerator capable of 40 MeV, 2 mA deuteron beams. Here, by referring to an existing 18F-fluorodeoxyglucose (FDG) distribution system we assumed that 99mTc radiopharmaceuticals formed after separating 99mTc from 99Mo can be delivered to hospitals from a radiopharmaceutical company within 6 h. The elution of 99mTc from 99Mo twice a day would meet about 50% of the demand for 99Mo.

  8. Shock processing of interstellar grains

    International Nuclear Information System (INIS)

    Seab, C.G.; Shull, J.M.

    1986-01-01

    Shock processing plays an important role in the life of a typical interstellar grain. Shocks of 100 km/s-l or greater can destroy about 50% of the grain material under appropriate preshock conditions of density and magnetic field. The destruction occurs by grain-grain collisions and nonthermal sputtering for steady state radiative shocks and by thermal sputtering for fast adiabatic shocks. The evaluation of the lifetime of grains against shock destruction depends on models of the interstellar medium (ISM) structure and on supernova remnants (SNR) evolution. Results from various authors give lifetimes between 10 to the 8th and 10 to the 9th power years, compared to typical injection times for new grains of a few times 10 to the 9th power years. These numbers require that a major portion of the interstellar silicon bearing grain material must be formed by grain growth in the ISM. At the same time, the presence of isotopic anomalies in some meteorites implies that at least some grains must survive from their formation in SNRs or red giant winds through incorporation into the solar system

  9. Irradiated microstructure of U-10Mo monolithic fuel plate at very high fission density

    Science.gov (United States)

    Gan, J.; Miller, B. D.; Keiser, D. D.; Jue, J. F.; Madden, J. W.; Robinson, A. B.; Ozaltun, H.; Moore, G.; Meyer, M. K.

    2017-08-01

    Monolithic U-10Mo alloy fuel plates with Al-6061 cladding are being developed for use in research and test reactors as low enrichment fuel (TEM characterization results for this U-10Mo/Zr/Al6061 monolithic fuel plate (∼59% U-235 enrichment) irradiated in Advanced Test Reactor at Idaho National Laboratory with an unprecedented high local fission density of 9.8E+21 fissions/cm3. The calculated fuel foil centerline temperature at the beginning of life and the end of life is 141 and 194 °C, respectively. TEM lamellas were prepared using focus ion beam lift-out technique. The estimated U-Mo fuel swelling, based on the fuel foil thickness change from SEM, is approximately 76%. Large bubbles (>1 μm) are distributed evenly in U-Mo and interlink of these bubbles is evident. The average size of subdivided grains at this fission density appears similar to that at 5.2E+21 fissions/cm3. The measured average Mo and Zr content in the fuel matrix is ∼30 at% and ∼7 at%, respectively, in general agreement with the calculated Mo and Zr from fission density.

  10. Modelling of grain refinement driven by negative grain boundary energy

    Czech Academy of Sciences Publication Activity Database

    Fischer, F. D.; Zickler, G. A.; Svoboda, Jiří

    2017-01-01

    Roč. 97, č. 23 (2017), s. 1963-1977 ISSN 1478-6435 R&D Projects: GA ČR(CZ) GA15-06390S Institutional support: RVO:68081723 Keywords : grain refinement * grain nucleation * distribution concept * jump on distribution function Subject RIV: BJ - Thermodynamics OBOR OECD: Thermodynamics Impact factor: 1.505, year: 2016

  11. Substituting maize grain with barley grain in concentrates fed to ...

    African Journals Online (AJOL)

    The aim of the study was to determine the effect of substituting maize grain with barley grain in the diet of lactating Jersey cows grazing kikuyu-ryegrass pasture. Sixty Jersey cows were blocked in terms of number of days in milk, lactation number, milk yield and live weight and randomly assigned to one of five treatments (n ...

  12. Characterization and study of reduction and sulfurization processing in phase transition from molybdenum oxide (MoO{sub 2}) to molybdenum disulfide (MoS{sub 2}) chalcogenide semiconductor nanoparticles prepared by one-stage chemical reduction method

    Energy Technology Data Exchange (ETDEWEB)

    Shomalian, K.; Bagheri-Mohagheghi, M.M.; Ardyanian, M. [Damghan University, School of Physics, Damghan (Iran, Islamic Republic of)

    2017-01-15

    In this research, molybdenum disulfide (MoS{sub 2}) nanoparticles were prepared by chemical reduction method using MoO{sub 3} and thiourea as a precursor. The physical properties of the synthesized MoO{sub 2}-MoS{sub 2} nanoparticles annealed at different temperatures of 200, 300, 750 C have been investigated, before and after exposure to sulfur vapor. The nanostructure of nanoparticles has been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) analyses and UV-Vis spectrophotometer. The X-ray diffraction analysis showed the formation of MoS{sub 2} single phase at annealing temperature of 750 C in the presence of sulfur vapor. The Raman spectrum of the nanoparticles revealed that the formation of MoS{sub 2} at 750 C after annealing in sulfur vapor. The values of band gap were obtained in the range of 3.64-3.17 eV and 3.47-1.95 eV for MoS{sub 2} nanoparticles before and after exposure to sulfur vapor, respectively. According to SEM images, the grain size decreases with increasing annealing temperature up to 750 C. Also, nanoplate-nanoparticles of MoS{sub 2} are formed at annealing temperature of 200-750 C. The TEM images of MoS{sub 2} nanoparticles at T{sub a} = 750 C confirm that the nanoparticles have a homogeneous distribution with a hexagonal structure. The FTIR spectra of the MoS{sub 2} nanoparticles showed the peaks at about 467 cm {sup -1} belong to the characteristic bands of Mo-S. (orig.)

  13. Preparation of fine-grained Mo–12Si–8.5B alloys with improved mechanical properties via a mechanical alloying process

    International Nuclear Information System (INIS)

    Li, Bin; Zhang, Guo-jun; Feng, Jiang; Shuai, Ren; Gang, Liu; Jun, Sun

    2014-01-01

    Highlights: • Fine-grained Mo–12Si–8.5B alloys were prepared by hot pressing sintering. • The microstructure control is achieved by mechanical alloying process. • The yield stress and especial the flexure strength of alloys are superior. - Abstract: Mo–12Si–8.5B alloys were prepared using mechanical alloying (MA) followed by hot pressing. The mechanical alloying (MA) process of elemental powder mixtures was used to synthesize the uniform and supersaturated powders. The microstructure exhibits a continuous and uniform α-Mo matrix in which the spherical Mo 3 Si and Mo 5 SiB 2 particles are distributed. In a more detailed observation of the microstructure, some nanoscale phases consisting of Mo 3 Si or Mo 5 SiB 2 also precipitated from the α-Mo matrix, which may involve the dissolving out of some Si and B atoms from the metastable supersaturated α-Mo synthesized by the mechanical alloying process. The MA process not only refined the microstructure of the subsequently sintered alloys by decreasing the grain sizes of both the α-Mo and intermetallics phases but also strengthened the α-Mo matrix by solid solution strengthening and dispersion strengthening. Consequently, the yield strength and flexure strength of the alloy prepared from the mechanically alloyed powders were 1915 MPa and 1137 MPa, respectively, which were superior to those of the alloy prepared by the mixed powders. The discussion was presented by combining with the fracture morphology

  14. Annealing effect in structural and electrical properties of sputtered Mo thin film

    Energy Technology Data Exchange (ETDEWEB)

    Chelvanathan, P.; Zakaria, Z. [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Yusoff, Y. [Department of Electrical, Electronic and System Engineering, FKAB, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Akhtaruzzaman, M. [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Alam, M.M. [Advanced Materials Research Chair, Chemistry Department, College of Sciences, King Saud University, Riyadh 11451 (Saudi Arabia); Alghoul, M.A.; Sopian, K. [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Amin, N., E-mail: nowshadamin@yahoo.com [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Electrical, Electronic and System Engineering, FKAB, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Advanced Materials Research Chair, Chemistry Department, College of Sciences, King Saud University, Riyadh 11451 (Saudi Arabia)

    2015-04-15

    Highlights: • We deposited Mo thin film by DC-sputtering for solar cell back contact application. • We examined the changes in the film quality in terms of structural, and electrical upon vacuum thermal annealing. • Vacuum thermal annealing at different temperature changes the degree of preferred orientation of (1 1 0) and (2 1 1) significantly. • Correlation of structural and electrical parameters was carried out. - Abstract: In this study, the effects of vacuum annealing on the structural and electrical properties of DC-sputtered molybdenum (Mo) thin films have been investigated. Mo thin films were deposited by DC sputtering and subsequently subjected to vacuum annealing in a tube furnace from 350 to 500 °C. Films that were deposited with different temperatures showed good adhesion with soda lime glass substrate after “tape testing”. X-ray diffraction (XRD) spectra have indicated existence of (1 1 0) and (2 1 1) orientations. However, I(1 1 0)/I(2 1 1) peak intensity ratio decreased for all vacuum annealed Mo films compared to as-sputtered films indicating change of preferential orientation. This suggests vacuum annealing can be employed to tailor the Mo thin film atomic packing density of the plane parallel to the substrate. SEM images of surface morphology clearly show compact and dense triangular like grains for as-sputtered film, while annealed films at 350 °C, 400 °C and 450 °C indicate rice-like grains. Stony grains with less uniformity were detected for films annealed for 500 °C. Meanwhile, electrical resistivity is insensitive to the vacuum annealing condition as all films showed more or less same resistivity in the range of 3 × 10{sup −5}–6 × 10{sup −5} Ω cm.

  15. A comparative study of the abrasive wear behavior of MoSi2

    International Nuclear Information System (INIS)

    Hawk, J.A.; Alman, D.E.

    1995-01-01

    This study is a preliminary assessment of the abrasive wear behavior of monolithic MoSi 2 . Comparisons with the wear behavior of other advanced materials, such as refractory metals, intermetallic compounds (i.e., TiAl, Fe 3 Al), and ceramics (i.e., Si 3 N 4 , ZrO 2 , and Al 2 O 3 ), are made. In general, the wear behavior of MoSi 2 is similar to oxide ceramics, due in large part to the high relative hardness of the compound. However, as with most brittle materials, as the hardness of the abrasive increases relative to the hardness of the wearing material (i.e., MoSi 2 abraded on garnet at 13 GPa versus abrasion on SiC at 24 GPa), volume wear increases; and the dominant wear mechanism changes, from one of primarily edge fracture to one combining micro-cutting with significant micro-fracture and grain pull-out

  16. Alignment of suprathermally rotating grains

    Science.gov (United States)

    Lazarian, A.

    1995-12-01

    It is shown that mechanical alignment can be efficient for suprathermally rotating grains, provided that they drift with supersonic velocities. Such a drift should be widely spread due to both Alfvenic waves and ambipolar diffusion. Moreover, if suprathermal rotation is caused by grain interaction with a radiative flux, it is shown that mechanical alignment may be present even in the absence of supersonic drift. This means that the range of applicability of mechanical alignment is wider than generally accepted and that it can rival the paramagnetic one. We also study the latter mechanism and re-examine the interplay between poisoning of active sites and desorption of molecules blocking the access to the active sites of H_2 formation, in order to explain the observed poor alignment of small grains and good alignment of large grains. To obtain a more comprehensive picture of alignment, we briefly discuss the alignment by radiation fluxes and by grain magnetic moments.

  17. Autonomous grain combine control system

    Science.gov (United States)

    Hoskinson, Reed L.; Kenney, Kevin L.; Lucas, James R.; Prickel, Marvin A.

    2013-06-25

    A system for controlling a grain combine having a rotor/cylinder, a sieve, a fan, a concave, a feeder, a header, an engine, and a control system. The feeder of the grain combine is engaged and the header is lowered. A separator loss target, engine load target, and a sieve loss target are selected. Grain is harvested with the lowered header passing the grain through the engaged feeder. Separator loss, sieve loss, engine load and ground speed of the grain combine are continuously monitored during the harvesting. If the monitored separator loss exceeds the selected separator loss target, the speed of the rotor/cylinder, the concave setting, the engine load target, or a combination thereof is adjusted. If the monitored sieve loss exceeds the selected sieve loss target, the speed of the fan, the size of the sieve openings, or the engine load target is adjusted.

  18. Interdiffusion among U-Mo-Zr and alloys of Al to 550oC

    International Nuclear Information System (INIS)

    Komar Varela, C.L; Arico, S.F; Gribaudo, L.M

    2006-01-01

    The international community, by means of the project 'Reduced Enrichment for Research and Test Reactors' is interested in the development of a new nuclear fuel of very high density of uranium and low enrichment (≤ 20% de U 235 ) for reactors of investigation and production of radioisotopes, that permit to reach greater neutron flows, with good capacity to be reprocessed One of these assemblies are the alloys of U with Mo contents between 7 and 10% in weight. In the fuels 'dispersed type plate' the particles of U-Mo are mixed with dust of aluminum and are co - laminated between two plates of an alloy of the same material. The existing contact among the particles permits the interdiffusion of the materials with the consequent apparition of new phases. Studies pursuit-irradiation have shown a badly behavior of these new phases. It is for this that is necessary to control the presence of these products of interaction. The aggregate of a third element to the alloys U - Mo has begun to be practiced with this purpose. In this work the modification of the start of the disorder of the phase γU in the alloy U-7%Mo-1%Zr was studied and the interdiffusion between pure aluminum and the same alloy to 550 o C. The results obtained are compared with other obtained for peers U-Mo/Al. The techniques of characterization utilized were: optical microscopy, analysis by diffraction of X-rays and microanalysis quantitative by microprobe electronic. It was observed that the aggregate of Zr refines the grain for a processing of homogenized in composition of Mo to 1000 o C and accelerates the start of the disorder of the phase γU to 550 o C. As for the zone of interaction, was found that the composed identifying do not they differ to them reported in the in peers U-Mo/Al. These are: (U,Mo)Al 4 y UAl 3 (AG)

  19. Effect of Solutes on Grain Refinement of As-Cast Fe-4Si Alloy

    Science.gov (United States)

    Li, Ming; Li, Jian-Min; Zheng, Qing; Wang, Geoff; Zhang, Ming-Xing

    2018-03-01

    Grain size is one of the key microstructural factors that control the mechanical properties of steels. The present work aims to extend the theories of grain refinement which were established for cast light alloys to steel systems. Using a designed Fe-4 wt pct Si alloy (all-ferrite structure during whole solidification process), the solute effect on grain refinement/grain coarsening in ferritic systems was comprehensively investigated. Experimental results showed that boron (B), which is associated with the highest Q value (growth restriction factor) in ferrite, significantly refined the as-cast structure of the Fe-4 wt pct Si alloy. Cu and Mo with low Q values had no effect on grain refinement. However, although Y and Zr have relatively high Q values, addition of these two solutes led to grain coarsening in the Fe-4Si alloy. Understanding the results in regards to the growth restriction factor and the driving force for the solidification led to the conclusion that in addition to the grain growth restriction effect, the changes of thermodynamic driving force for solidification due to the solute addition also played a key role in grain refinement in ferritic alloys.

  20. Methods of assessing grain-size distribution during grain growth

    DEFF Research Database (Denmark)

    Tweed, Cherry J.; Hansen, Niels; Ralph, Brian

    1985-01-01

    This paper considers methods of obtaining grain-size distributions and ways of describing them. In order to collect statistically useful amounts of data, an automatic image analyzer is used, and the resulting data are subjected to a series of tests that evaluate the differences between two related...... distributions (before and after grain growth). The distributions are measured from two-dimensional sections, and both the data and the corresponding true three-dimensional grain-size distributions (obtained by stereological analysis) are collected. The techniques described here are illustrated by reference...

  1. Prevalence of IgE antibodies to grain and grain dust in grain elevator workers

    International Nuclear Information System (INIS)

    Lewis, D.M.; Romeo, P.A.; Olenchock, S.A.

    1986-01-01

    IgE-mediated allergic reactions have been postulated to contribute to respiratory reactions seen in workers exposed to grain dusts. In an attempt better to define the prevalence of IgE antibodies in workers exposed to grain dusts, we performed the radioallergosorbent test (RAST) on worker sera using both commercial allergens prepared from grain and worksite allergens prepared from grain dust samples collected at the worksite. We found that the two types of reagents identified different populations with respect to the specificity of IgE antibodies present. The RAST assay performed using worksite allergens correlated well with skin test procedures. These results may allow us to gain better understanding of allergy associated with grain dust exposure, and document the utility of the RAST assay in assessment of occupational allergies

  2. Defects-tolerant Co-Cr-Mo dental alloys prepared by selective laser melting.

    Science.gov (United States)

    Qian, B; Saeidi, K; Kvetková, L; Lofaj, F; Xiao, C; Shen, Z

    2015-12-01

    CrCoMo alloy specimens were successfully fabricated using selective laser melting (SLM). The aim of this study was to carefully investigate microstructure of the SLM specimens in order to understand the influence of their structural features inter-grown on different length scales ranging from nano- to macro-levels on their mechanical properties. Two different sets of processing parameters developed for building the inner part (core) and the surface (skin) of dental prostheses were tested. Microstructures were characterized by SEM, EBSD and XRD analysis. The elemental distribution was assessed by EDS line profile analysis under TEM. The mechanical properties of the specimens were measured. The microstructures of both specimens were characterized showing formation of grains comprised of columnar sub-grains with Mo-enrichment at the sub-grain boundaries. Clusters of columnar sub-grains grew coherently along one common crystallographic direction forming much larger single crystal grains which are intercrossing in different directions forming an overall dendrite-like microstructure. Three types of microstructural defects were occasionally observed; small voids (10 μm). Despite the presence of these defects, the yield and the ultimate tensile strength (UTS) were 870 and 430MPa and 1300MPa and 1160MPa, respectively, for the skin and core specimens which are higher than casted dental alloy. Although the formation of microstructural defects is hard to be avoided during the SLM process, the SLM CoCrMo alloys can achieve improved mechanical properties than their casted counterparts, implying they are "defect-tolerant". Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. MATHEMATICAL MODEL OF GRAIN MICRONIZATION

    Directory of Open Access Journals (Sweden)

    V. A. Afanas’ev

    2014-01-01

    Full Text Available Summary. During micronisation grain moisture evaporates mainly in decreasing drying rate period. Grain layer located on the surface of the conveyor micronisers will be regarded as horizontal plate. Due to the fact that the micronisation process the surface of the grain evaporates little moisture (within 2-7 % is assumed constant plate thickness. Because in the process of micronization grain structure is changing, in order to achieve an exact solution of the equations necessary to take into account changes thermophysical, optical and others. Equation of heat transfer is necessary to add a term that is responsible for the infrared heating. Because of the small thickness of the grain, neglecting the processes occurring at the edge of the grain, that is actually consider the problem of an infinite plate. To check the adequacy of the mathematical model of the process of micronisation of wheat grain moisture content must be comparable to the function of time, obtained by solving the system of equations with the measured experimental data of experience. Numerical solution of a system of equations for the period of decreasing drying rate is feasible with the help of the Maple 14, substituting the values of the constants in the system. Calculation of the average relative error does not exceed 7- 10 %, and shows a good agreement between the calculated data and the experimental values.

  4. Why Is It Important to Eat Grains, Especially Whole Grains?

    Science.gov (United States)

    ... nutrients, including dietary fiber , several B vitamins (thiamin, riboflavin, niacin, and folate), and minerals ( iron , magnesium , and selenium). Dietary fiber from whole grains or other foods, may help reduce blood cholesterol levels and may ...

  5. Virginia Grain Sorghum Performance Tests, 2016

    OpenAIRE

    Balota, Maria; Oakes, Joseph; Mehl, H. L.; Acharya, Bhupendra

    2017-01-01

    Offers data about the grain sorghum testing program, and evaluations of commercial and experimental varieties of grain sorghum. Statistical analyses are provided, as well as information on relative yield, grain moisture, head mold, and more.

  6. Virginia Grain Sorghum Performance Tests, 2015

    OpenAIRE

    Balota, Maria; Oakes, Joseph; Thomason, Wade Everett; Pitman, Robert Melvin, 1948-; Mehl, H. L.

    2016-01-01

    Offers data about the grain sorghum testing program, and evaluations of commercial and experimental varieties of grain sorghum. Statistical analyses are provided, as well as information on relative yield, grain moisture, head mold, and more.

  7. Mo(ve)ment-methodology

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Christian Celosse-Andersen, Martin

    2018-01-01

    conditions and identity formation, are discussed in relation to criminological theories of gang desistance. The paper illustrates how the mo(ve)ment methodology was applied in a study of comprehensive processes of identity (re)formation and gang exit processes. This study was conducted with Martin, a former......This paper describes the theoretical basis for and development of a moment-movement research methodology, based on an integration of critical psychological practice research and critical ethnographic social practice theory. Central theoretical conceptualizations, such as human agency, life...

  8. Estimation of grain boundary diffusivity in near-α titanium polycrystals

    International Nuclear Information System (INIS)

    Brockman, Robert A.; Pilchak, Adam L.; John Porter, W.; John, Reji

    2011-01-01

    The role of enhanced grain boundary diffusivity in high-temperature diffusion of interstitial elements through metals is widely recognized but poorly characterized in most materials. This paper summarizes an effort to estimate grain boundary diffusivity of oxygen in a near-α titanium alloy, Ti-6Al-2Sn-4Zr-2Mo-0.1Si, by explicitly incorporating microstructure obtained from electron backscatter diffraction into an analytical model. Attention is focused on near-surface diffusion behavior contributing to the rapid ingress of oxygen and possible crack initiation in high-temperature environments.

  9. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  10. TEM Characterization of High Burn-up Microstructure of U-7Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jian Gan; Brandon Miller; Dennis Keiser; Adam Robinson; James Madden; Pavel Medvedev; Daniel Wachs

    2014-04-01

    As an essential part of global nuclear non-proliferation effort, the RERTR program is developing low enriched U-Mo fuels (< 20% U-235) for use in research and test reactors that currently employ highly enriched uranium fuels. One type of fuel being developed is a dispersion fuel plate comprised of U-7Mo particles dispersed in Al alloy matrix. Recent TEM characterizations of the ATR irradiated U-7Mo dispersion fuel plates include the samples with a local fission densities of 4.5, 5.2, 5.6 and 6.3 E+21 fissions/cm3 and irradiation temperatures of 101-136?C. The development of the irradiated microstructure of the U-7Mo fuel particles consists of fission gas bubble superlattice, large gas bubbles, solid fission product precipitates and their association to the large gas bubbles, grain subdivision to tens or hundreds of nanometer size, collapse of bubble superlattice, and amorphisation. This presentation will describe the observed microstructures specifically focusing on the U-7Mo fuel particles. The impact of the observed microstructure on the fuel performance and the comparison of the relevant features with that of the high burn-up UO2 fuels will be discussed.

  11. Stress induced martensite transformation in Co–28Cr–6Mo alloy during room temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, S., E-mail: song_cai@fwmetals.com [Fort Wayne Metals Research Products Corporation, 9609 Ardmore Avenue, Fort Wayne, IN 46809 (United States); Daymond, M.R. [Department of Mechanical and Materials Engineering, Queen' s University, Nicol Hall, 60 Union Street, Kingston, Ontario, Canada K7L 3N6 (Canada); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700S. Cass Avenue, 433/D008, Argonne, IL 60439 (United States)

    2013-09-15

    The phase transformation and texture change of two Co–28Cr–6Mo alloys during room temperature deformation were studied by using the in-situ synchrotron X-ray diffraction. It is found that a slight difference in chemical compositions can significantly change the phase constitutions and the mechanical properties. For the material with less Ni, C and N (lower α-phase stability), increasing the grain size promotes the athermal martensite transformation during cooling. The kinetics of the Stress Induced Martensite (SIM) phase transformation may be more affected by the athermal martensite instead of the grain size of the α-phase. After deformation, similar textures are produced in samples regardless the differences in the initial structures such as the phase constitution and the grain size; while a relatively strong {111} texture and a weak {100} texture are produced in the α-phase, a {101"¯1} fiber texture is gradually developed in the ε-phase during uniaxial tension.

  12. Reheat cracking in 1/2 CrMoV steel. Heat affected zones

    International Nuclear Information System (INIS)

    Batte, A.D.; Miller, R.C.; Murphy, M.C.

    1976-01-01

    Low alloy creep resisting steels are inherently susceptible to cracking during stress relief heat treatment (reheat cracking) though few welds give rise to problems in manufacture or service. Mechanical tests on simulated affected zone structures in CrMoV forgings have shown that cracking occurs when the high temperature ductility is inadequate to accommodate the residual welding strain. Differences in susceptibility result from differences in heat affected zone grain size if the purity level is sufficiently high; reheat cracking may then be avoided by ensuring complete grain refinement during welding. The susceptibility of a lower purity forging was insensitive to grain size; heat affected zone refinement is unlikely to eliminate cracking in such steel. (orig.) [de

  13. Mo99 Production Plant Layout

    Energy Technology Data Exchange (ETDEWEB)

    Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Naranjo, Angela Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-25

    The NorthStar Medical Technologies 99Mo production facility configuration is envisioned to be 8 accelerator pairs irradiating 7 100Mo targets (one spare accelerator pair undergoing maintenance while the other 7 pairs are irradiating targets). The required shielding in every direction for the accelerators is initially estimated to be 10 feet of concrete. With the accelerator pairs on one (ground) level and spaced with the required shielding between adjacent pairs, the only practical path for target insertion and removal while minimizing floor space is vertical. The current scheme then requires a target vertical lift of nominally 10 feet through a shield stack. It is envisioned that the lift will be directly into a hot cell where an activated target can be removed from its holder and a new target attached and lowered. The hot cell is on a rail system so that a single hot cell can service all active target locations, as well as deliver the ready targets to the separations lab. On this rail system, coupled to the hot cell, will be a helium recovery and clean-up system. All helium coolant equipment is located on the upper level near to the target removal point.

  14. Type IIIa cracking at 2CrMo welds in 1/2CrMoV pipework

    Energy Technology Data Exchange (ETDEWEB)

    Brett, S.J.; Smith, P.A. [National Power plc, Swindon (United Kingdom)

    1998-12-31

    The most common form of in-service defect found today on the welds of National Power`s 1/2CrMoV pipework systems is Type IV cracking which occurs in intercritically transformed material at the edge of the heat affected zone. However an alternate form of cracking, termed IIIa, which occurs close to the weld fusion line in fully grain refined heat affected zones, has also been observed. The incidence of Type IIIa cracking has increased in recent years and these defects now constitute a significant part of the total recorded crack population. This presentation describes Type IIIa cracking and compares and contrasts it with the better documented Type IV cracking. Particular reference is made to the role of carbon diffusion at the weld fusion line in promoting Type IIIa damage in preference to Type IV. (orig.) 5 refs.

  15. Edge termination of MoS2 and CoMoS catalyst particles

    DEFF Research Database (Denmark)

    Byskov, Line Sjolte; Nørskov, Jens Kehlet; Clausen, B. S.

    2000-01-01

    The edge termination of MoS2 and CoMoS catalyst particles is studied by density functional calculations. We show that for structures without vacancies Mo-terminated edges have the lowest edge energies. Creation of vacancies, which are believed to be active sites in these catalyst systems, leads...

  16. On the reduction of orthorhombic MoO3 to MoO2

    International Nuclear Information System (INIS)

    Delannay, F.

    1982-01-01

    Electron diffraction shows evidence of topotactic orientation relationships between the original MoO 3 crystal and MoO 2 crystals formed under mild reduction conditions. These relationships differ from previously published literature data. A possible mechanism of formation of the [100] strings of edge sharing octahedra in the MoO 2 structure is tentatively proposed. (author)

  17. Effect of graphite content on magnetic and mechanical properties of TiC-TiN-Mo-Ni cermets

    Science.gov (United States)

    Zhang, Man; Yang, Qingqing; Xiong, Weihao; Huang, Bin; Ruan, Linji; Mao, Qiao; Li, Shengtao

    2018-04-01

    TiC-10TiN-6Mo-xGr-yNi (mol%, Gr represents graphite, x = 0, 2, 4, 6, 8, and y = 15, 30) cermets were prepared by powder metallurgy method, in order to inverstigate the effect of Gr content on magnetic and mechanical properties of TiC-TiN-Mo-Ni cermets. Room-temperature (RT) saturation magnetization (Ms) and remanence (Mr) of cermets increased with increasing x. This was mainly attributed to that the total content of non-ferromagnetic carbonitride-forming elements Ti and Mo in Ni-based binder phase decreased with increasing x. At the same x, cermets for y = 15 had lower RT Ms and Mr than those for y = 30. Cermets containing more than 2 mol% Gr became ferromagnetic at RT. Bending strength of cermets first increased and then decreased with increasing x. It reached the maximum at x = 2, mainly due to high total content of solutes Ti and Mo in Ni-based binder phase, and moderate thickness of outer rim of Ti(C,N) ceramic grains. Hardness of cermets was not significantly affected by x, mainly due to the combined action of the decrease of the total content of Ti and Mo in binder phase and the increase of the volume fraction of ceramic grains. At the same x, cermets for y = 15 had lower bending strength and higher hardness than those for y = 30.

  18. Electron beam-induced structural transformations of MoO3 and MoO3−x crystalline nanostructures

    International Nuclear Information System (INIS)

    Diaz-Droguett, D. E.; Zuñiga, A.; Solorzano, G.; Fuenzalida, V. M.

    2012-01-01

    Electron beam-induced damage and structural changes in MoO 3 and MoO 3−x single crystalline nanostructures were revealed by in situ transmission electron microscopy (TEM) examination (at 200 kV) after few minutes of concentrating the electron beam onto small areas (diameters between 25 and 200 nm) of the samples. The damage was evaluated recording TEM images, while the structural changes were revealed acquiring selected area electron diffraction patterns and high resolution transmission electron microscopy (HRTEM) images after different irradiation times. The as-received nanostructures of orthorhombic MoO 3 were transformed to a Magnéli’s phase of the oxide (γ-Mo 4 O 11 ) after ∼10 min of electron beam irradiation. The oxygen loss from the oxide promoted structural changes. HRTEM observations showed that, in the first stage of the reduction, oxygen vacancies generated by the electron beam are accommodated by forming crystallographic shear planes. At a later stage of the reduction process, a polycrystalline structure was developed with highly oxygen-deficient grains. The structural changes can be attributed to the local heating of the irradiated zone combined with radiolysis.

  19. Electron beam-induced structural transformations of MoO{sub 3} and MoO{sub 3-x} crystalline nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Droguett, D. E., E-mail: dodiaz@fis.puc.cl [Pontificia Universidad Catolica de Chile, Departamento de Fisica, Facultad de Fisica (Chile); Zuniga, A. [Universidad de Chile, Departamento de Ingenieria Mecanica, Facultad de Ciencias Fisicas y Matematicas (Chile); Solorzano, G. [PUC-RIO, Departamento de Ciencia dos Materiais e Metalurgia, DCMM (Brazil); Fuenzalida, V. M. [Universidad de Chile, Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas (Chile)

    2012-01-15

    Electron beam-induced damage and structural changes in MoO{sub 3} and MoO{sub 3-x} single crystalline nanostructures were revealed by in situ transmission electron microscopy (TEM) examination (at 200 kV) after few minutes of concentrating the electron beam onto small areas (diameters between 25 and 200 nm) of the samples. The damage was evaluated recording TEM images, while the structural changes were revealed acquiring selected area electron diffraction patterns and high resolution transmission electron microscopy (HRTEM) images after different irradiation times. The as-received nanostructures of orthorhombic MoO{sub 3} were transformed to a Magneli's phase of the oxide ({gamma}-Mo{sub 4}O{sub 11}) after {approx}10 min of electron beam irradiation. The oxygen loss from the oxide promoted structural changes. HRTEM observations showed that, in the first stage of the reduction, oxygen vacancies generated by the electron beam are accommodated by forming crystallographic shear planes. At a later stage of the reduction process, a polycrystalline structure was developed with highly oxygen-deficient grains. The structural changes can be attributed to the local heating of the irradiated zone combined with radiolysis.

  20. Complex Chemistry on Interstellar Grains

    Science.gov (United States)

    Widicus Weaver, Susanna L.; Kelley, Matthew J.; Blake, Geoffrey A.

    Early interstellar chemical models considered complex molecule formation on grains [Allen & Robinson (1977)], but current models assume that simple molecules form on grains and subsequent gas phase ion-molecule reactions produce the more complex species [Ruffle & Herbst (2001), Charnley (2001)]. It has been shown, however, that gas phase ion-molecule reactions are insufficient for the production of such complex organic species as ethanol (CH3CH2OH) and methyl formate (CH3OCHO) [Horn et al. (2004)]. Organics such as acetaldehyde (CH3CHO), ethanol, methyl formate, acetic acid (CH3COOH), and glycolaldehyde (CH2OHCHO) have also been detected in high abundance in regions of grain mantle disruption or evaporation, indicating that these species are formed on grain surfaces [see Chengalur & Kanekar (2003), Bottinelli et al. (2004), Hollis et al. (2001)]. The mechanisms for complex molecule production on grains are clearly much more important, and much more complex, than has been recognized. Recent observational studies of these types of species have offered insight into the mechanisms for their possible grain surface synthesis. The relative hot core abundances of the 2C structural isomers methyl formate, acetic acid, and glycolaldehyde (52:2:1, respectively [Hollis et al. (2001)]) indicate that if they form on grains it is not from kinetically-controlled single-atom addition reactions. Likewise, the 3C aldose sugar, glyceraldehyde (CH2OHCHOHCHO), was not detected in Sgr B2(N-LMH) [Hollis et al. (2004)] while the 3C ketose sugar, dihydroxyacetone (CO(CH2OH)2) was detected in this source [Widicus Weaver & Blake (2005)]. Chemical pathways favoring the more stable carbonates over acids and aldehydes are required to explain these results. Interestingly, all of these species can be formed from reactions involving the abundant grain mantle constituents CO, HCOOH, and CH3OH and their radical precursors. A model has been developed to investigate this type of chemical network, and

  1. Ammonia treated Mo/AC catalysts for CO hydrogenation with ...

    Indian Academy of Sciences (India)

    SHARIF F ZAMAN

    K-Ni-Mo catalyst. The interaction of activated carbon with the Ni-Mo species prevents the complete reduc- tion of the active metals (Ni0 and Mo0 lead to methane formation) and preserves partially oxidized Mo and Ni species, which are thought to be active sites for alcohol formation.14 Zhang et al.,15 synthesized Ni-Mo-K ...

  2. Catalyseur d'hydrocraquage à base de sulfure de NiMo déposé sur une zéolithe HEMT modifiée

    Science.gov (United States)

    Baalala, M.; Becue, T.; Leglise, J.; Manoli, J. M.; van Gestel, J. N. M.; Lamotte, J.; Bensitel, M.; Goupil, J. M.; Cornet, D.

    1999-02-01

    Treating a NH4EMT zeolite with a solution of (NH4)2SiF6 at 80 °C affords a solid containing amorphous SiO2 intimately mixed with the zeolite. This acidic support EMT-Si was loaded with NiMo sulfide in order to prepare a bifunctional catalyst, which was tested for the hydrogenation of benzene and the hydrocracking of n-heptane. This NiMo/EMT-Si catalyst was found more active for hydrogenation than the analogous NiMo/HY. This is ascribed to a higher dispersion of the NiMo sulfide, which is almost equally shared between the internal mesopores in the modified EMT solid, and the fissures, which were created throughout the zeolite grains upon inserting the NiMo sulfide. The catalyst with the EMT-Si support was also found more active than the NiMo/HY for the hydrocracking of heptane, with a slightly higher selectivity into heptane isomers. Le traitement d'une zéolithe NH4EMT par une solution de (NH4)2SiF6 fournit un solide comportant une phase SiO2 amorphe intimement mélangée aux parties intactes de la zéolithe. Sur ce support acide EMT-Si, on a greffé un sulfure de NiMo afin de préparer un catalyseur bifonctionnel qui a été testé dans les réactions d'hydrogénation du benzène et d'hydrocraquage du n-heptane. Ce catalyseur NiMo/EMT-Si s'avère plus actif en hydrogénation que son analogue NiMo/HY, en raison d'une meilleure dispersion du sulfure de NiMo. Sur le solide EMT modifié, le sulfure se répartit à peu près également entre les mésopores internes et les fissures crées dans les grains de zéolithe lors de l'insertion du sulfure de NiMo. Au contraire sur le support Y, une partie du sulfure est externe aux grains de zéolithe et inactive en catalyse. Le catalyseur NiMo/EMT-Si est aussi trouvé plus actif que le NiMo/HY en hydrocraquage du n-heptane, et un peu plus sélectif en isomères.

  3. The levels of zinc and molybdenum in hair and food grain in areas of high and low incidence of esophageal cancer: a comparative study.

    Science.gov (United States)

    Ray, S S; Das, D; Ghosh, T; Ghosh, A K

    2012-06-25

    The outcome of different studies on the role of Zn & Mo in esophageal cancer (EC) is conflicting. Here, the levels of those elements in hair as well as food grain of two different ethnic populations across two continents have been studied to explore their role in EC. Two different ethnic populations are taken from (i) Eastern Cape, South Africa (RSA), an area of very high incidence of EC and (ii) West Bengal, India, an area of low incidence of that disease. Each ethnic population is divided into two groups: case and control (n=30 for all groups). Hair samples from all groups and food grain from RSA and India are analyzed for Zn & Mo content. This study shows a strong correlation between reduced levels of those elements in hair and the development of EC in RSA (both Zn &Mo: p hair even with respect to Indian case group (Zn: pFood grain from RSA has significantly reduced level of those elements with respect to India (both Zn & Mo: p food grains can be correlated to the deficiency of those elements in hair of RSA population. The deficiency of Zn & Mo can be correlated to the development of EC.

  4. Nucleation and growth mechanisms of Al2O3 atomic layer deposition on synthetic polycrystalline MoS2

    Science.gov (United States)

    Zhang, H.; Chiappe, D.; Meersschaut, J.; Conard, T.; Franquet, A.; Nuytten, T.; Mannarino, M.; Radu, I.; Vandervorst, W.; Delabie, A.

    2017-02-01

    Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) are of great interest for applications in nano-electronic devices. Their incorporation requires the deposition of nm-thin and continuous high-k dielectric layers on the 2D TMDs. Atomic layer deposition (ALD) of high-k dielectric layers is well established on Si surfaces: the importance of a high nucleation density for rapid layer closure is well known and the nucleation mechanisms have been thoroughly investigated. In contrast, the nucleation of ALD on 2D TMD surfaces is less well understood and a quantitative analysis of the deposition process is lacking. Therefore, in this work, we investigate the growth of Al2O3 (using Al(CH3)3/H2O ALD) on MoS2 whereby we attempt to provide a complete insight into the use of several complementary characterization techniques, including X-ray photo-electron spectroscopy, elastic recoil detection analysis, scanning electron microscopy, and time-of-flight secondary ion mass spectrometry. To reveal the inherent reactivity of MoS2, we exclude the impact of surface contamination from a transfer process by direct Al2O3 deposition on synthetic MoS2 layers obtained by a high temperature sulfurization process. It is shown that Al2O3 ALD on the MoS2 surface is strongly inhibited at temperatures between 125°C and 300°C, with no growth occurring on MoS2 crystal basal planes and selective nucleation only at line defects or grain boundaries at MoS2 top surface. During further deposition, the as-formed Al2O3 nano-ribbons grow in both vertical and lateral directions. Eventually, a continuous Al2O3 film is obtained by lateral growth over the MoS2 crystal basal plane, with the point of layer closure determined by the grain size at the MoS2 top surface and the lateral growth rate. The created Al2O3/MoS2 interface consists mainly of van der Waals interactions. The nucleation is improved by contributions of reversible adsorption on the MoS2 basal planes by using low

  5. Sustainable production of grain crops for biofuels

    Science.gov (United States)

    Grain crops of the Gramineae are grown for their edible, starchy seeds. Their grain is used directly for human food, livestock feed, and as raw material for many industries, including biofuels. Using grain crops for non-food uses affects the amount of food available to the world. Grain-based biofuel...

  6. Development of Perennial Grain Sorghum

    Directory of Open Access Journals (Sweden)

    Stan Cox

    2018-01-01

    Full Text Available Perennial germplasm derived from crosses between Sorghum bicolor and either S. halepense or S. propinquum is being developed with the goal of preventing and reversing soil degradation in the world’s grain sorghum-growing regions. Perennial grain sorghum plants produce subterranean stems known as rhizomes that sprout to form the next season’s crop. In Kansas, breeding perennial sorghum involves crossing S. bicolor cultivars or breeding lines to S. halepense or perennial S. bicolorn × S. halepense breeding lines, selecting perennial plants from F2 or subsequent populations, crossing those plants with S. bicolor, and repeating the cycle. A retrospective field trial in Kansas showed that selection and backcrossing during 2002–2009 had improved grain yields and seed weights of breeding lines. Second-season grain yields of sorghum lines regrowing from rhizomes were similar to yields in the first season. Further selection cycles have been completed since 2009. Many rhizomatous lines that cannot survive winters in Kansas are perennial at subtropical or tropical locations in North America and Africa. Grain yield in Kansas was not correlated with rhizomatousness in either Kansas or Uganda. Genomic regions affecting rhizome growth and development have been mapped, providing new breeding tools. The S. halepense gene pool may harbor many alleles useful for improving sorghum for a broad range of traits in addition to perenniality.

  7. Grain growth in UO2

    International Nuclear Information System (INIS)

    Hastings, I.J.; Scoberg, J.A.; Walden, W.

    1979-06-01

    Grain growth studies have been carried out on UO 2 to provide data for the fuel modelling program and to evaluate fuel fabricated in commissioning the Mixed Oxide Fuel Fabrication Laboratory at Chalk River Nuclear Laboratories. Fuel examined includes natural UO 2 commercially fabricated from ADU powder for CANDU reactors; natural UO 2 commercially fabricated from AU powder; natural UO 2 from ADU and AU powder, fabricated in the MOFFL; and commercially fabricated UO 2 enriched 1.7, 4.5, and 9.6 wt. percent U-235 in U. Samples were step-annealed in vacuo at 1870-2070 K for up to 32.5 h. All data fit a (grain size)sup(2.5) versus annealing time relationship. Apparent activation energy for grain growth, Q, depends on fuel type and varies from 150+-10 kJ/mol for early AU powder to 360+-10 kJ/mol for pellets from ADU fabricated in the MOFFL. Grain sizes calculated using the laboratory equation in a fuel performance code tend to be greater than those measured in irradiated natural fuel, suggesting irradiation-induced inhibition of grain growth. However, any inhibition is equivalent to that expected for a systematic 5 percent underpredicition in reactor power. (author)

  8. Development of fission Mo-99 production technology

    International Nuclear Information System (INIS)

    Park, Jin Ho; Choung, W. M.; Lee, K. I. and others

    2000-05-01

    Fission Mo-99 is the only parent nuclide of Tc-99m, an extremely useful tool for mdeical diagnosis, with an estimated usage of greater than 80% of nuclear medicine applicatons. HEU and LEU targets to optimize in HANARO irradiation condition suggested and designed for domestic production of fission Mo-99. The optimum process conditions are established in each unit process to meet quality requirements of fission Mo-99 products, and the results of performance test in combined process show Mo separation and purification yield of the above 97%. The concept of Tc generator production process is established, and the result of performance test show Tc production yield of 98.4% in Tc generator procuction process. The drafts is prepared for cooperation of technical cooperation and business investment with foreign country. Evaluation on economic feasibility is accompanied for fission Mo-99 and Tc-99m generator production

  9. Development of fission Mo-99 production technology

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Choung, W. M.; Lee, K. I. and others

    2000-05-01

    Fission Mo-99 is the only parent nuclide of Tc-99m, an extremely useful tool for mdeical diagnosis, with an estimated usage of greater than 80% of nuclear medicine applicatons. HEU and LEU targets to optimize in HANARO irradiation condition suggested and designed for domestic production of fission Mo-99. The optimum process conditions are established in each unit process to meet quality requirements of fission Mo-99 products, and the results of performance test in combined process show Mo separation and purification yield of the above 97%. The concept of Tc generator production process is established, and the result of performance test show Tc production yield of 98.4% in Tc generator procuction process. The drafts is prepared for cooperation of technical cooperation and business investment with foreign country. Evaluation on economic feasibility is accompanied for fission Mo-99 and Tc-99m generator production.

  10. Nanostructure of and structural defects in a Mo2BC hard coating investigated by transmission electron microscopy and atom probe tomography

    Science.gov (United States)

    Gleich, Stephan; Fager, Hanna; Bolvardi, Hamid; Achenbach, Jan-Ole; Soler, Rafael; Pradeep, Konda Gokuldoss; Schneider, Jochen M.; Dehm, Gerhard; Scheu, Christina

    2017-08-01

    In this work, the nanostructure of a Mo2BC hard coating was determined by several transmission electron microscopy methods and correlated with the mechanical properties. The coating was deposited on a Si (100) wafer by bipolar pulsed direct current magnetron sputtering from a Mo2BC compound target in Ar at a substrate temperature of 630 °C. Transmission electron microscopy investigations revealed structural features at various length scales: bundles (30 nm to networks of several micrometers) consisting of columnar grains (˜10 nm in diameter), grain boundary regions with a less ordered atomic arrangement, and defects including disordered clusters (˜1.5 nm in diameter) as well as stacking faults within the grains. The most prominent defect with a volume fraction of ˜0.5% is the disordered clusters, which were investigated in detail by electron energy loss spectroscopy and atom probe tomography. The results provide conclusive evidence that Ar is incorporated into the Mo2BC film as disordered Ar-rich Mo-B-C clusters of approximately 1.5 nm in diameter. Hardness values of 28 ± 1 GPa were obtained by nanoindentation tests. The Young's modulus of the Mo2BC coating exhibits a value of 462 ± 9 GPa, which is consistent with ab initio calculations for crystalline and defect free Mo2BC and measurements of combinatorically deposited Mo2BC thin films at a substrate temperature of 900 °C. We conclude that a reduction of the substrate temperature of 270 °C has no significant influence on hardness and Young's modulus of the Mo2BC hard coating, even if its nanostructure exhibits defects.

  11. Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion

    International Nuclear Information System (INIS)

    Wang Peiming; Wilson, Leslie L.; Wesolowski, David J.; Rosenqvist, Joergen; Anderko, Andrzej

    2010-01-01

    To investigate the behavior of molybdenum dissolution products in systems that approximate localized corrosion environments, solubility of Mo(III) in equilibrium with solid MoO 2 has been determined at 80 deg. C as a function of solution acidity, chloride concentration and partial pressure of hydrogen. The measurements indicate a strong increase in solubility with acidity and chloride concentration and a weak effect of hydrogen partial pressure. The obtained results have been combined with literature data for systems containing Mo(III), Mo(IV), and Mo(VI) in solutions to develop a comprehensive thermodynamic model of aqueous molybdenum chemistry. The model is based on a previously developed framework for simulating the properties of electrolyte systems ranging from infinite dilution to solid saturation or fused salt limit. To reproduce the measurements, the model assumes the presence of a chloride complex of Mo(III) (i.e., MoCl 2+ ) and hydrolyzed species (MoOH 2+ , Mo(OH) 2 + , and Mo(OH) 3 0 ) in addition to the Mo 3+ ion. The model generally reproduces the experimental data within experimental scattering and provides a tool for predicting the phase behavior and speciation in complex, concentrated aqueous solutions. Thus, it provides a foundation for simulating the behavior of molybdenum species in localized corrosion environments.

  12. Sticking properties of ice grains

    Directory of Open Access Journals (Sweden)

    Jongmanns M.

    2017-01-01

    Full Text Available We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced particle radii, which differ significantly from the linear dependence of common contact theories.

  13. Sticking properties of ice grains

    Science.gov (United States)

    Jongmanns, M.; Kumm, M.; Wurm, G.; Wolf, D. E.; Teiser, J.

    2017-06-01

    We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced) particle radii, which differ significantly from the linear dependence of common contact theories.

  14. Fractal dust grains in plasma

    International Nuclear Information System (INIS)

    Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

    2012-01-01

    Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

  15. Preparation of MoSex>3/Mo-NPs catalytic films for enhanced hydrogen evolution by pulsed laser ablation of MoSe2 target

    Science.gov (United States)

    Fominski, V. Yu.; Romanov, R. I.; Fominski, D. V.; Shelyakov, A. V.

    2018-02-01

    The peculiarities of pulsed laser ablation of MoSe2 targets which caused the formation of a complex plume containing atoms (Mo and Se) and Mo nanoparticles (Mo-NPs) have been studied. Investigations of the composition, structure, and catalytic activity toward the hydrogen evolution reaction (HER) for MoSex/Mo-NPs films prepared by pulsed laser deposition (PLD) in a vacuum and in a buffer He gas were carried out. For He pressure of 30 Pa, a shock wave could be the dominant mechanism of material transport, resulting in the deposition of an Se-enriched flux of chemically active atoms and leading to the growth of amorphous films with an increased Se content. Mo nanoparticles allowed for a larger surface area of the MoSex∼3.1/Mo-NPs catalyst deposited 5 cm from the target. However, for deposition in He at 10 cm, the amount of Mo NPs in the film appreciably decreased. Factors that could impact on the transport of nanoparticles through a buffer gas were considered. The amorphous MoSex∼3.1/Mo-NPs films prepared by PLD in He gas exhibited excellent HER performance. Quasicrystal MoSex<2/Mo-NPs films obtained by vacuum PLD were obviously inferior to amorphous films. Despite the formation of edge-oriented MoSe2 nanocrystals, the vacuum-deposited films had a large majority of metallic Mo and a deficiency of Se, which could adversely affect their HER performance.

  16. The annealing effects on the micro-structure and properties of RuMoC films as seedless barrier for advanced Cu metallization

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Jianxiong; Liu, Bo, E-mail: liubo2009@scu.edu.cn, E-mail: gh.jiao@siat.ac.cn [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Jiao, Guohua, E-mail: liubo2009@scu.edu.cn, E-mail: gh.jiao@siat.ac.cn; Lu, Yuanfu; Dong, Yuming [Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences, Shenzhen 518055 (China); The Chinese University of Hong Kong, Hong Kong (China); Li, Qiran [Institut d' Electronique Fondamentale, CNRS-Université Paris Sud UMR 8622, 91405 Orsay (France)

    2016-09-07

    100 nm thick RuMoC films and 5 nm thick RuMoC films with Cu capping have been deposited on Si(111) by magnetron co-sputtering with Ru and MoC confocal targets. The samples were subsequently annealed at temperatures ranging from 450 to 650 °C in vacuum at a pressure of 3 × 10{sup −4} Pa to study the annealing effects on the microstructures and properties of RuMoC films for advanced seedless Cu metallization applications. The sheet resistances, residual oxygen contents, and microstructures of the RuMoC films have close correlation with the doping contents of Mo and C, which can be easily controlled by the deposition power ratio of MoC versus Ru targets (DPR). When DPR was 0.5, amorphous RuMoC film (marked as RuMoC II) with low sheet resistances and residual oxygen contents was obtained. The fundamental relationship between the annealing temperatures with the microstructures and properties of the RuMoC films was investigated, and a critical temperature point was revealed at about 550 °C where the components and microstructures of the RuMoC II films changed obviously. Results indicated that below 550 °C, the RuMoC II films remained amorphous due to the well-preserved C-Ru and C-Mo bonds. However, above 550 °C, the microstructures of RuMoC II films transformed from amorphous to nano-composite structure due to the breakage of Ru-C bonds, while the supersaturated solid solution MoC segregated out along the grain boundaries of Ru, thus hindering the diffusion of Cu and O atoms. This is the main mechanism of the excellent thermal stability of the RuMoC films after annealing at high temperatures. The results indicated great prospects of amorphous RuMoC films in advanced seedless Cu metallization applications.

  17. PESTICIDES USE AMONG GRAIN MERCHANTS IN MUBI GRAIN ...

    African Journals Online (AJOL)

    AGROSEARCH UIL

    Key words: Pesticides, food security, grain merchants, storage, perception. INTRODUCTION. Food security in sub-Saharan Africa largely depends upon improved food productivity through the use of sustainable agricultural practices and the reduction of post-harvest losses caused by pests and diseases (Adedire, 2001).

  18. Pesticides Use among Grain Merchants in Mubi Grain Markets of ...

    African Journals Online (AJOL)

    It is, therefore, recommended that farmers, retailers, distributors and all the pesticide workers should undergo regular training/workshop on the use and safety measures of pesticides. Also multimedia awareness activities in local language should be massively conducted. Key words: Pesticides, food security, grain merchants ...

  19. Applied Thermodynamics: Grain Boundary Segregation

    Directory of Open Access Journals (Sweden)

    Pavel Lejček

    2014-03-01

    Full Text Available Chemical composition of interfaces—free surfaces and grain boundaries—is generally described by the Langmuir–McLean segregation isotherm controlled by Gibbs energy of segregation. Various components of the Gibbs energy of segregation, the standard and the excess ones as well as other thermodynamic state functions—enthalpy, entropy and volume—of interfacial segregation are derived and their physical meaning is elucidated. The importance of the thermodynamic state functions of grain boundary segregation, their dependence on volume solid solubility, mutual solute–solute interaction and pressure effect in ferrous alloys is demonstrated.

  20. The Antinutritional Components of Grains

    DEFF Research Database (Denmark)

    Madsen, Claus Krogh; Brinch-Pedersen, Henrik

    2016-01-01

    Grains provide humans and farmed animals with a very large proportion of the energy and macro- and micronutrients they need. Unfortunately, grains also contain compounds that interfere with the utilization of the nutrients by animals. These so-called antinutritionals may result in poor resource u......, biotechnology, and food chemistry....... utilization, increased costs in meat production, and even malnourishment in humans. The major antinutritionals are phytate, proteinaceous inhibitors of digestive enzymes, tannins, and nonstarch polysaccharides. For each compound, countermeasures are available in the diverse fields of plant breeding...

  1. Characteristics of MoSe{sub 2} formation during rapid thermal processing of Mo-coated glass

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soobin; Koo, Jaseok; Kim, Sammi [School of Chemical Engineering, Yeungnam University, Gyeonsan, Gyeongbuk 712-749 (Korea, Republic of); Kim, Soo-Hyun [School of Materials Science and Engineering, Yeungnam University, Gyeonsan, Gyeongbuk 712-749 (Korea, Republic of); Cheon, Taehoon [Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873 (Korea, Republic of); Oh, Jong Seok; Kim, Suk Jin [AVACO Co., Ltd., Daegu 704-833 (Korea, Republic of); Kim, Woo Kyoung, E-mail: wkim@ynu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeonsan, Gyeongbuk 712-749 (Korea, Republic of)

    2013-05-01

    Multi-layered Mo, prepared using an in-line sputtering system, was selenized by reaction with Se vapor and thermal annealing of bilayer Mo/Se samples. In situ high-temperature X-ray diffraction analysis indicated that the phase evolution of the glass/Mo/Se sample during heat treatment was similar to that of the selenization of glass/Mo with Se vapor, except for crystallization of Se in the glass/Mo/Se sample. However, the MoSe{sub 2} layer formed from the selenization of the Mo layer by Se vapor preferentially grew perpendicularly to the Mo surface, whereas MoSe{sub 2} formed from the reaction of Mo with Se liquid showed random orientation. The detailed reaction pathways of the double-layer random-MoSe{sub 2}/vertical-MoSe{sub 2} formation from the Mo/Se bilayer sample were suggested on the basis of the several characterization results including X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and selected-area electron diffraction patterns. - Highlights: ► The selenization of glass/Mo and glass/Mo/Se samples was investigated. ► The reaction of the Mo layer with Se vapor produced vertically oriented MoSe{sub 2}. ► Randomly oriented MoSe{sub 2} layer was formed from the reaction of Mo with liquid Se.

  2. AMORE Mo-99 Spike Test Results

    Energy Technology Data Exchange (ETDEWEB)

    Youker, Amanda J. [Argonne National Lab. (ANL), Argonne, IL (United States); Krebs, John F. [Argonne National Lab. (ANL), Argonne, IL (United States); Quigley, Kevin J. [Argonne National Lab. (ANL), Argonne, IL (United States); Byrnes, James P. [Argonne National Lab. (ANL), Argonne, IL (United States); Rotsch, David A [Argonne National Lab. (ANL), Argonne, IL (United States); Brossard, Thomas [Argonne National Lab. (ANL), Argonne, IL (United States); Wesolowski, Kenneth [Argonne National Lab. (ANL), Argonne, IL (United States); Alford, Kurt [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-09-27

    With funding from the National Nuclear Security Administrations Material Management and Minimization Office, Argonne National Laboratory (Argonne) is providing technical assistance to help accelerate the U.S. production of Mo-99 using a non-highly enriched uranium (non-HEU) source. A potential Mo-99 production pathway is by accelerator-initiated fissioning in a subcritical uranyl sulfate solution containing low enriched uranium (LEU). As part of the Argonne development effort, we are undertaking the AMORE (Argonne Molybdenum Research Experiment) project, which is essentially a pilot facility for all phases of Mo-99 production, recovery, and purification. Production of Mo-99 and other fission products in the subcritical target solution is initiated by putting an electron beam on a depleted uranium (DU) target; the fast neutrons produced in the DU target are thermalized and lead to fissioning of U-235. At the end of irradiation, Mo is recovered from the target solution and separated from uranium and most of the fission products by using a titania column. The Mo is stripped from the column with an alkaline solution. After acidification of the Mo product solution from the recovery column, the Mo is concentrated (and further purified) in a second titania column. The strip solution from the concentration column is then purified with the LEU Modified Cintichem process. A full description of the process can be found elsewhere [1–3]. The initial commissioning steps for the AMORE project include performing a Mo-99 spike test with pH 1 sulfuric acid in the target vessel without a beam on the target to demonstrate the initial Mo separation-and-recovery process, followed by the concentration column process. All glovebox operations were tested with cold solutions prior to performing the Mo-99 spike tests. Two Mo-99 spike tests with pH 1 sulfuric acid have been performed to date. Figure 1 shows the flow diagram for the remotely operated Mo-recovery system for the AMORE project

  3. Large-area few-layer MoS 2 deposited by sputtering

    KAUST Repository

    Huang, Jyun-Hong

    2016-06-06

    Direct magnetron sputtering of transition metal dichalcogenide targets is proposed as a new approach for depositing large-area two-dimensional layered materials. Bilayer to few-layer MoS2 deposited by magnetron sputtering followed by post-deposition annealing shows superior area scalability over 20 cm(2) and layer-by-layer controllability. High crystallinity of layered MoS2 was confirmed by Raman, photo-luminescence, and transmission electron microscopy analysis. The sputtering temperature and annealing ambience were found to play an important role in the film quality. The top-gate field-effect transistor by using the layered MoS2 channel shows typical n-type characteristics with a current on/off ratio of approximately 10(4). The relatively low mobility is attributed to the small grain size of 0.1-1 mu m with a trap charge density in grain boundaries of the order of 10(13) cm(-2).

  4. MoOx thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

    Directory of Open Access Journals (Sweden)

    Can Liu

    2013-11-01

    Full Text Available In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoOx films (2 ≤ x ≤ 2.3 deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li2SO4. The MoOx (x ≈ 2.3 film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm−2 measured at 5 mV s−1, best rate capability and excellent stability at potentials below −0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO2 nanocrystals and amorphous MoOx (2.3 < x ≤ 3. A mechanism combining Mo(IV oxidation/reduction on the hydrated MoO2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.

  5. Interface structure and composition of MoO3/GaAs(0 0 1)

    Science.gov (United States)

    Sarkar, Anirban; Ashraf, Tanveer; Grafeneder, Wolfgang; Koch, Reinhold

    2018-04-01

    We studied growth, structure, stress, oxidation state as well as surface and interface structure and composition of thermally-evaporated thin MoO3 films on the technologically important III/V-semiconductor substrate GaAs(0 0 1). The MoO3 films grow with Mo in the 6+  oxidation state. The electrical resistance is tunable by the oxygen partial pressure during deposition from transparent insulating to semi-transparant halfmetallic. In the investigated growth temperature range (room temperature to 200 °C) no diffraction spots are detected by x-ray diffraction. However, high resolution transmission electron microscopy reveals the formation of MoO3 nanocrystal grains with diameters of 5–8 nm. At the interface a  ≈3 nm-thick intermediate layer has formed, where the single-crystal lattice of GaAs gradually transforms to the nanocrystalline MoO3 structure. This interpretation is corroborated by our in situ and real-time stress measurements evidencing a two-stage growth process as well as by elemental interface analysis revealing coexistance of Ga, As, Mo, and oxygen in a intermediate layer of 3–4 nm.

  6. Transistors and tunnel diodes enabled by large-scale MoS2 nanosheets grown on GaN

    Science.gov (United States)

    San Yip, Pak; Zou, Xinbo; Cho, Wai Ching; Wu, Kam Lam; Lau, Kei May

    2017-07-01

    We report growth, fabrication, and device results of MoS2-based transistors and diodes implemented on a single 2D/3D material platform. The 2D/3D platform consists of a large-area MoS2 thin film grown on SiO2/p-GaN substrates. Atomic force microscopy, scanning electron microscopy, and Raman spectroscopy were used to characterize the thickness and quality of the as-grown MoS2 film, showing that the large-area MoS2 nanosheet has a smooth surface morphology constituted by small grains. Starting from the same material, both top-gated MoS2 field effect transistors and MoS2/SiO2/p-GaN heterojunction diodes were fabricated. The transistors exhibited a high on/off ratio of 105, a subthreshold swing of 74 mV dec-1, field effect mobility of 0.17 cm2 V-1 s-1, and distinctive current saturation characteristics. For the heterojunction diodes, current-rectifying characteristics were demonstrated with on-state current density of 29 A cm-2 and a current blocking property up to -25 V without breakdown. The reported transistors and diodes enabled by the same 2D/3D material stack present promising building blocks for constructing future nanoscale electronics.

  7. Development of fission Mo-99 production technology

    International Nuclear Information System (INIS)

    Park, Jin Ho; Choung, W. M.; Lee, K. I. and others

    2001-05-01

    This R and D project is planed to supply domestic demands of Mo-99 through fission route, and consequently this project will be expected to rise up utilization of HANARO and KAERI's capability for marketing extension into domestic and oversea radiopharmaceutical market. HEU and LEU target types are decided and designed for fission Mo-99 production in domestic. Experimental study of target fabrication technology was performed and developed processing equipments. And conceptual design of target loading/unloading in/from HANARO device are performed. Tracer test of Mo-99 separation and purification process was performed, test results reach to Mo-99 recovery yield above 80% and decontamination factor above 1600. Combined Mo-99 separation and purification process was decided for hot test scheduled from next year, and performance test was performed. Conceptual design for modification of existing hot cell for fission Mo-99 production facility was performed and will be used for detail design. Assumption for the comparison of LEU and HEU target in fission Mo-99 production process were suggested and compared of merits and demerits in view of fabrication technology and economy feasibility

  8. Development of fission Mo-99 production technology

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Choung, W. M.; Lee, K. I. and others

    2001-05-01

    This R and D project is planed to supply domestic demands of Mo-99 through fission route, and consequently this project will be expected to rise up utilization of HANARO and KAERI's capability for marketing extension into domestic and oversea radiopharmaceutical market. HEU and LEU target types are decided and designed for fission Mo-99 production in domestic. Experimental study of target fabrication technology was performed and developed processing equipments. And conceptual design of target loading/unloading in/from HANARO device are performed. Tracer test of Mo-99 separation and purification process was performed, test results reach to Mo-99 recovery yield above 80% and decontamination factor above 1600. Combined Mo-99 separation and purification process was decided for hot test scheduled from next year, and performance test was performed. Conceptual design for modification of existing hot cell for fission Mo-99 production facility was performed and will be used for detail design. Assumption for the comparison of LEU and HEU target in fission Mo-99 production process were suggested and compared of merits and demerits in view of fabrication technology and economy feasibility.

  9. Stress-driven grain growth

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1998-11-13

    Full Text Available This article shows the differences of two-dimensional polycrystal of a material with a rectangular unit cell with lattice spacing b and b (1 + epsilon), subjected to a uniform external stress sigma. Consider a grain in which the lattice vector...

  10. Microstructure and magnetic properties of FePt film with combined MoC/(Mg–X)O (X=Cu, Ni, Co) intermediate layers

    International Nuclear Information System (INIS)

    Tsai, Jai-Lin; Tzeng, Jie-Lin; Hu, Keng-Chun; Li, Hsu-Kang; Pan, Zu-Yu; Chang, Yuan-Shuo; Liao, Chang-Chun

    2017-01-01

    The magnetic properties and microstructure of FePt films grown on MoC layer and MoC/(Mg–X)O (X=Cu, Ni, Co) combined intermediate layers were studied. The (Mg–X)O (X=Cu, Ni, Co) layer with thickness of 5 nm was deposited on CrRu seed layer at 395 °C. The CrRu (200) texture was enhanced which may due to well grains growth in specific orientation and small lattice mismatch with (Mg–X)O (X=Cu, Ni, Co). Finally, the FePt/MoC layers were deposited on (Mg–X)O layer at 425 °C. Using MoC/MgCuO combined intermediate layers, the rocking width of FePt (001) and CrRu (200) diffraction peak were changed from 7.1° to 6.1°, and 5.7° to 3.8°, respectively. For MoC/MgCoO dual intermediate layers, the rocking width of FePt (001) and CrRu (200) diffraction peak were 6.7° and 4.1°. The FePt/MoC/MgCoO film illustrates perpendicular magnetic anisotropy with out-of plane coercivity of 9.3 kOe which is higher than FePt film deposited on MoC layer (8.5 kOe) and the in-plane loops is linear. From microstructure, the FePt grains were more separated on MoC/(Mg–X)O (X=Cu, Ni, Co) combined intermediate layers. - Highlights: • The MgCoO intermediate layer was resisted the Cr diffusion. • The MgCoO capped layer promote the CrRu(200) texture. • The FePt film shows high perpendicular magnetization on MoC/MgCoO layer.

  11. Continuous Measurements of Recrystallization and Grain Growth in Cobalt Super Alloys

    Science.gov (United States)

    Keyvani, Mahsa; Garcin, Thomas; Fabrègue, Damien; Militzer, Matthias; Yamanaka, Kenta; Chiba, Akihiko

    2017-05-01

    L605 (20Cr-15W-10Ni wt pct) and CCM (28Cr-6Mo wt pct) cobalt-based superalloys are candidates for a wide range of applications, from gas turbine components to biomedical implants. Attention is currently focused on the optimization of grain structure as an appropriate approach to increase yield stress without affecting significantly the ductility. In this study, the Laser Ultrasonics for Metallurgy (LUMet) technology is used to examine in situ the evolution of the mean grain size associated with recrystallization and grain growth during heat treatments from the cold-rolled state. The recrystallization process is completed at 1373 K (1100 °C) for L605 and 1273 K (1000 °C) for CCM. The subsequent grain growth rate in L605 is larger compared to CCM. Continuous measurements of the grain size evolution are found to be consistent with grain growth affected by solute drag. Through in situ measurements, the laser ultrasonic technology significantly accelerates the determination of metallurgical parameters allowing for fast optimization of process parameters required to meet specific applications.

  12. Concepts on Low Temperature Mechanical Grain Growth

    Energy Technology Data Exchange (ETDEWEB)

    Sharon, John Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.; Boyce, Brad Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.

    2013-11-01

    In metals, as grain size is reduced below 100nm, conventional dislocation plasticity is suppressed resulting in improvements in strength, hardness, and wears resistance. Existing and emerging components use fine grained metals for these beneficial attributes. However, these benefits can be lost in service if the grains undergo growth during the component’s lifespan. While grain growth is traditionally viewed as a purely thermal process that requires elevated temperature exposure, recent evidence shows that some metals, especially those with nanocrystalline grain structure, can undergo grain growth even at room temperature or below due to mechanical loading. This report has been assembled to survey the key concepts regarding how mechanical loads can drive grain coarsening at room temperature and below. Topics outlined include the atomic level mechanisms that facilitate grain growth, grain boundary mobility, and the impact of boundary structure, loading scheme, and temperature.

  13. 134Ba diffusion in polycrystalline BaMO3 (M = Ti, Zr, Ce)

    Science.gov (United States)

    Sažinas, Rokas; Sakaguchi, Isao; Einarsrud, Mari-Ann; Grande, Tor

    2017-11-01

    Cation diffusion in functional oxide materials is of fundamental interest, particularly in relation to interdiffusion of cations in thin film heterostructures and chemical stability of materials in high temperature electrochemical devices. Here we report on 134Ba tracer diffusion in polycrystalline BaMO3 (M = Ti, Zr, Ce) materials. The dense BaMO3 ceramics were prepared by solid state sintering, and thin films of 134BaO were deposited on the polished pellets by drop casting of an aqueous solution containing the Ba-tracer. The samples were subjected to thermal annealing and the resulting isotope distribution profiles were recorded by secondary ion mass spectrometry. The depth profiles exhibited two distinct regions reflecting lattice and grain boundary diffusion. The grain boundary diffusion was found to be 4-5 orders of magnitude faster than the lattice diffusion for all three materials. The temperature dependence of the lattice and grain boundary diffusion coefficients followed an Arrhenius type behaviour, and the activation energy and pre-exponential factor demonstrated a clear correlation with the size of the primitive unit cell of the three perovskites. Diffusion of Ba via Ba-vacancies was proposed as the most likely diffusion mechanism.

  14. Effect of Laser Heat Treatment on Microstructures of 1Cr5Mo Steel Welded Joint

    Directory of Open Access Journals (Sweden)

    GUO Wei

    2017-01-01

    Full Text Available The surface of 1Cr5Mo heat-resistant steel welded joint was treated with CO2 laser,the microstructure and grain size grades of welded joints before and after laser heat treatment (LHT were analyzed with 4XC type optical microscope (OM,and the distribution of residual stress and retained austenite content in the surface of the welded joints were measured with X-ray diffraction (XRD stress tester.The results show that the grains of 1Cr5Mo steel welded joints are refined by LHT,and the microstructure uniformity improves significantly,the grain levels of welded zone,fusion zone,overheated zone and normalized zone increase from level 9,level 9.8,level 8 and level 10.7 to level 10,level 10.2,level 8.5 and level 11 respectively,the mechanical weak areas reduce from overheated zone,welded zone and fusion zone to the overheated zone.The tensile residual stress in the welded joint surface is eliminated by LHT and a layer of compressive residual stress with thickness of about 0.28mm is formed.The residual austenite content in the welded joint surface increases after LHT,of which the distribution is more uniform and conducive to the improvement of mechanical properties.

  15. CVD grown 2D MoS2 layers: A photoluminescence and fluorescence lifetime imaging study

    International Nuclear Information System (INIS)

    Oezden, Ayberk; Madenoglu, Buesra; Sar, Hueseyin; Ay, Feridun; Perkgoez, Nihan Kosku; Yeltik, Aydan; Sevik, Cem

    2016-01-01

    In this letter, we report on the fluorescence lifetime imaging and accompanying photoluminescence properties of a chemical vapour deposition (CVD) grown atomically thin material, MoS 2 . μ-Raman, μ-photoluminescence (PL) and fluorescence lifetime imaging microscopy (FLIM) are utilized to probe the fluorescence lifetime and photoluminescence properties of individual flakes of MoS 2 films. Usage of these three techniques allows identification of the grown layers, grain boundaries, structural defects and their relative effects on the PL and fluorescence lifetime spectra. Our investigation on individual monolayer flakes reveals a clear increase of the fluorescence lifetime from 0.3 ns to 0.45 ns at the edges with respect to interior region. On the other hand, investigation of the film layer reveals quenching of PL intensity and lifetime at the grain boundaries. These results could be important for applications where the activity of edges is important such as in photocatalytic water splitting. Finally, it has been demonstrated that PL mapping and FLIM are viable techniques for the investigation of the grain-boundaries. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. The many facets of tunneling magnetoresistance in Sr_2FeMoO_6

    Science.gov (United States)

    Nag, Abhishek; Jana, Somnath; Middey, Srimanta; Ray, Sugata

    2017-08-01

    The nature and shape of the magnetoresistance versus magnetic field responses of polycrystalline Sr_2FeMoO_6 has been a matter of intense debate. Other than the conventional intergranular tunneling magnetoresistance with nonmagnetic grain boundaries as tunnel barriers, intragranular contributions due to the presence of magnetic anti-phase boundaries as barriers and magnetically frustrated grain surface barriers giving rise to spin-valve-type magnetoresistance also turn out to be important. We find that each of these descriptions are partially true, while it is the physical state of the sample resulting from different sample synthesis and treatment conditions that defines the relative contributions of different mechanisms. It is also shown that a purely conventional intergranular TMR response can be realized only when small grain, well ordered pellets are annealed at or above 1500°C. Low temperature annealing of already highly ordered samples lead to formation of SrMoO_4 patches which further modify the magnetoresistance of this material. The dissolution of this phase takes place only after annealing above 1100°C which leads to the enhancement in the moment and ordering of the sample.

  17. J-type Carbon Stars: A Dominant Source of 14 N-rich Presolar SiC Grains of Type AB

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Nan; Stephan, Thomas; Boehnke, Patrick; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua; Davis, Andrew M.; Trappitsch, Reto; Pellin, Michael J.

    2017-07-20

    We report Mo isotopic data of 27 new presolar SiC grains, including 12 N-14-rich AB (N-14/N-15 > 440, AB2) and 15 mainstream (MS) grains, and their correlated Sr and Ba isotope ratios when available. Direct comparison of the data for the MS grains, which came from low-mass asymptotic giant branch (AGB) stars with large s-process isotope enhancements, with the AB2 grain data demonstrates that AB2 grains show near-solar isotopic compositions and lack s-process enhancements. The near-normal Sr, Mo, and Ba isotopic compositions of AB2 grains clearly exclude born-again AGB stars, where the intermediate neutron-capture process (i-process) takes place, as their stellar source. On the other hand, low-mass CO novae and early R-and J-type carbon stars show C-13 and N-14 excesses but no s-process enhancements and are thus potential stellar sources of AB2 grains. Because both early R-type carbon stars and CO novae are rare objects, the abundant J-type carbon stars (10%-15% of all carbon stars) are thus likely to be a dominant source of AB2 grains.

  18. Small Grain Production Pt 2: Growth and Development of Small Grains

    OpenAIRE

    Jackson, Lee; Williams, Jack

    2006-01-01

    Part 2 of the 14-part Small Grain Production Manual describes the stages of small grain growth, including germination, tillering, vegetative growth, stem elongation, heading, flowering, grain filling, growth habit and yield components.

  19. Superplastic deformation behavior of a spray-deposited eutectic NiAl/Cr(Mo) alloy doped with Dy

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xinghao [National Sun Yat-Sen Univ., Kaohsiung, Taiwan (China). Inst of Materials Science and Engineering; Shenyang Institute of Aeronautical Engineering (China). Dept. of Materials Engineering; Wu, Baolin [Shenyang Institute of Aeronautical Engineering (China). Dept. of Materials Engineering; Huang, J.C. [National Sun Yat-Sen Univ., Kaohsiung, Taiwan (China). Inst of Materials Science and Engineering

    2007-02-15

    The tensile deformation behavior at elevated temperatures and the associated mechanisms are investigated for hot isostatically pressed NiAl-28Cr-5.9Mo-0.1Dy fabricated through spray forming. Superplasticity is observed at above 1323 K under an initial strain rate lower than 10{sup -3} s{sup -1} with an m value of 0.5. The activation energies for superplastic flow are found to be half of that for self-diffusion in NiAl. Grain boundary sliding between NiAl and adjacent NiAl or Cr(Mo) grains with local range accommodation, i. e., dynamic recovery, is suggested to be responsible for the superplastic deformation of the alloy. (orig.)

  20. Incorporation of MoS2 nanosheets in CoSb3 matrix as an efficient novel strategy to enhance its thermoelectric performance

    Science.gov (United States)

    Yadav, Suchitra; Chaudhary, Sujeet; Pandya, Dinesh K.

    2018-03-01

    The nanocomposite approach is considered as an effective way to improve the thermoelectric properties of bulk materials and we have exploited it by simultaneous though independent tackling of the electron and phonon transports. In the present study, through the strategy of anchoring the CoSb3 nanoparticles on the 2-dimensional nanosheets of MoS2, we demonstrate a controlled interplay of the newly created CoSb3/MoS2 interfaces in nanocomposites of varying concentration of MoS2 via significant enhancement of the phonon scattering without deterioration of electron transport. A concurrent occurrence of low energy carrier filtering on account of the interfacial potential barrier helps in beneficial manipulation of grain to grain carrier transport. The dimensionless figure of merit ZT maximizes to 0.53 at 600 K for the CoSb3/MoS2 nanocomposite containing 3 wt% of MoS2, 4-fold increase over the pristine CoSb3 in the 300-600 K range. This study paves the way towards improvement of the thermoelectric performance of p-type CoSb3 using 2D MoS2 as an interfacial additive.

  1. Pressure effect on grain boundary diffusion

    International Nuclear Information System (INIS)

    Smirnova, E.S.; Chuvil'deev, V.N.

    1997-01-01

    The influence of hydrostatic pressure on grain boundary diffusion and grain boundary migration in metallic materials is theoretically investigated. The model is suggested that permits describing changes in activation energy of grain boundary self-diffusion and diffusion permeability of grain boundaries under hydrostatic pressure. The model is based on the ideas about island-type structure of grain boundaries as well as linear relationship of variations in grain boundary free volume to hydrostatic pressure value. Comparison of theoretical data with experimental ones for a number of metals and alloys (α-Zr, Sn-Ge, Cu-In with Co, In, Al as diffusing elements) shows a qualitative agreement

  2. Pulsed cathodoluminescence and Raman spectra of MoS{sub 2} and WS{sub 2} nanocrystals and their combination MoS{sub 2}/WS{sub 2} produced by self-propagating high-temperature synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bozheyev, Farabi, E-mail: farabi.bozheyev@gmail.com [Institute of High Technology Physics, National Research Tomsk Polytechnic University, 30 Lenin Ave., 634050 Tomsk (Russian Federation); National Nanolaboratory, al-Farabi Kazakh National University, 71 al-Farabi Ave., 050000 Almaty (Kazakhstan); Nazarbayev University Research and Innovation System, 53 Kabanbay Batyr St., 010000 Astana (Kazakhstan); Valiev, Damir [Institute of High Technology Physics, National Research Tomsk Polytechnic University, 30 Lenin Ave., 634050 Tomsk (Russian Federation); Nemkayeva, Renata [National Nanolaboratory, al-Farabi Kazakh National University, 71 al-Farabi Ave., 050000 Almaty (Kazakhstan)

    2016-02-29

    Molybdenum and tungsten disulfide nanoplates were produced by self-propagating high-temperature synthesis in argon atmosphere. This method provides an easy way to produce MoS{sub 2} and WS{sub 2} from nanoplates up to single- and several layers. The Raman peak intensities corresponding to in-plane E{sup 1}{sub 2g} and out-of-plane A{sub 1g} vibration modes and their shifts strongly depend on the thicknesses of the MoS{sub 2} and WS{sub 2} platelets indicating size-dependent scaling laws and properties. An electron beam irradiation of MoS{sub 2} and WS{sub 2} powders leads to an occurrence of pulsed cathodoluminescence (PCL) spectra at 575 nm (2.15 eV) and 550 nm (2.25 eV) characteristic to their intrinsic band gaps. For the combination of MoS{sub 2} and WS{sub 2} nanopowders, a PCL shoulder at 430 nm (2.88 eV) was observed, which is explained by the radiative electron-hole recombination at the MoS{sub 2}/WS{sub 2} grain boundaries. The luminescence decay kinetics of the MoS{sub 2}/WS{sub 2} nanoplates appears to be slower than for individual MoS{sub 2} and WS{sub 2} platelets due to a spatial separation of electrons and holes at MoS{sub 2}/WS{sub 2} junction resulting in extension of recombination time.

  3. Grain centre mapping - 3DXRD measurements of average grain characteristics

    DEFF Research Database (Denmark)

    Oddershede, Jette; Schmidt, Søren; Lyckegaard, Allan

    2014-01-01

    Three-Dimensional X-ray Diraction (3DXRD) Microscopy is a generic term covering a variety of dierent techniques for characterising the mi- crostructure within the bulk of polycrystalline materials. One strategy | namely grain centre mapping | enables fast measurements of the av- erage characteris......Three-Dimensional X-ray Diraction (3DXRD) Microscopy is a generic term covering a variety of dierent techniques for characterising the mi- crostructure within the bulk of polycrystalline materials. One strategy | namely grain centre mapping | enables fast measurements of the av- erage...... and the closely related boxscan method is given. Both validation experiments and applications for in situ studies of microstructural changes during plastic deformation and crack growth are given. Finally an outlook with special emphasis on coupling the measured results with modelling is given....

  4. Migration du carbone et évolution structurale de liaisons hétérogènes soudées entre aciers ``ferritiques'' 2.25Cr-Mo et 9.5Cr-Mo-Nb-V

    Science.gov (United States)

    Tavassoli, Ali Asghar; Leclou, André

    1981-02-01

    Les caractéristiques mécaniques et structurales des liaisons hétérogènes soudées entre aciers ferritiques 2.25Cr-Mo et 9.5Cr-Mo-Nb-V (EM 12) ont été étudiées en fonction du temps de maintien aux températures 550, 650, 725 et 750°C. Ces études ont mis en évidence l'apparition d'une zone à gros grains du côté de 2.25Cr-Mo dont la largeur varie en fonction du temps et surtout de la température de maintien. Lorsque la partie courante de métal de base 2.25Cr-Mo présente une structure du type bainite revenue, la zone à gros grains présente une structure ferritique appauvrie en précipités. L'évolution de cette zone est décrite d'après le modèle du déplacement du front de diffusion et la largeur et la quantité de carbone migrée sont calculées pour les conditions de fonctionnement des générateurs de vapeur des réacteurs rapides.

  5. Simple thermodynamic model of the extension of solid solution of Cu-Mo alloys processed by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingenieria Metalurgica y de Materiales, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Valparaiso (Chile); Guzman, D. [Departamento de Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Pontificia Universidad Catolica de Valparaiso, Av. Los Carrera 01567, Quilpue (Chile); Ordonez, Stella [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. L. Bernardo O' Higgins 3363, Santiago (Chile); Rios, R. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, General Lagos 2086, Valdivia (Chile)

    2011-08-15

    Highlights: {yields} Extension of solid solution in Cu-Mo systems achieved by mechanical alloying. {yields} Simple thermodynamic model to explain extension of solid solution of Mo in Cu. {yields} Model gives results that are consistent with the solubility limit extension reported in other works. - Abstract: The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu-Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu-Cr, Cu-Nb and Cu-Fe systems processed by mechanical alloying.

  6. Floodplain Mapping Submission for Oregon County, MO

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Floodplain Mapping study deliverables depict and quantify the flood risks for Oregon County, MO. The City of Thayer and the Missouri State Emergency Management...

  7. Phase transformations in Mo-doped FINEMETs

    Energy Technology Data Exchange (ETDEWEB)

    Silveyra, Josefina M., E-mail: jsilveyra@fi.uba.a [Lab. de Solidos Amorfos, INTECIN, FIUBA-CONICET, Paseo Colon 850, (C1063ACV) Buenos Aires (Argentina); Illekova, Emilia; Svec, Peter; Janickovic, Dusan [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia); Rosales-Rivera, Andres [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Cremaschi, Victoria J. [Lab. de Solidos Amorfos, INTECIN, FIUBA-CONICET, Paseo Colon 850, (C1063ACV) Buenos Aires (Argentina)

    2010-06-15

    In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM. The thermal stability of the alloy was deteriorated as a consequence of Mo's smaller atomic size. The gradual replacement of Nb by Mo reduced the onset temperature of Fe-Si and of the borides. The Curie temperature of the amorphous phase slightly decreased from 594 K for x=0 to 587 K for x=3. The borides compounds Fe{sub 2}B and Fe{sub 23}B{sub 6} as well as the (Nb,Mo){sub 5}Si{sub 3} phase were found to precipitate in the second and third crystallization.

  8. Alternative energy resources for MoDOT

    Science.gov (United States)

    2011-02-01

    This research investigates environmentally friendly alternative energy sources that could be used by MoDOT in various areas, and develops applicable and sustainable strategies to implement those energy sources.

  9. Anisotropy oxidation of textured ZrB2–MoSi2 ceramics

    DEFF Research Database (Denmark)

    Liu, Hai-Tao; Zou, Ji; Ni, De Wei

    2012-01-01

    Oxidation behavior of hot forged textured ZrB2–20vol% MoSi2 ceramics with platelet ZrB2 grains was investigated at 1500°C for exposure time from 0.5 to 12h. Compared to untextured ceramics, the textured ceramics showed obvious anisotropic oxidation behavior and the surface normal to the hot forging...... pressure demonstrated better oxidation resistance. Such improvement in the oxidation resistance is primarily considered as a higher intrinsic ZrB2 atomic density on the orientated {00l} planes in the textured ceramics. It is expectable that the anisotropic textured ZrB2–MoSi2 ceramics can offer better...

  10. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, MoO2

    Directory of Open Access Journals (Sweden)

    Felipe Legorreta-García

    2015-05-01

    Full Text Available The synthesis of Fe3+, Mo4+ and Y3+ fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD, scanning electron microscopy (SEM and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe3+, Mo4+ and Y3+ ions in the zirconia tetragonal monophase, even after calcinations.

  11. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, Mo)O {sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Legorreta-Garcia, F.; Esperanza Hernandez-Cruz, L.; Villanueva-Ibanez, M.; Flores-Gonzalez, M. A.

    2015-10-01

    The synthesis of Fe{sup 3}+, Mo{sup 4+} and Y{sup 3+} fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM) results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe{sup 3+}, Mo{sup 4+} and Y{sup 3+} ions in the zirconia tetragonal monophase, even after calcinations. (Author)

  12. High-energy synchrotron study of in-pile-irradiated U–Mo fuels

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin; Mo, Kun; Ye, Bei; Jamison, Laura; Mei, Zhi-Gang; Gan, Jian; Miller, Brandon; Madden, James; Park, Jun-Sang; Almer, Jonathan; Bhattacharya, Sumit; Kim, Yeon Soo; Hofman, Gerard L.; Yacout, Abdellatif M.

    2016-03-01

    Here synchrotron scattering analysis results on U–7wt.%Mo fuel specimens irradiated in the Advanced Test Reactor to three burnup levels (3.0, 5.2, and 6.3 × 1021 fission/cm3) are reported. Mature fission gas bubble superlattice was observed to form at intermediate burnup. The superlattice constant was determined to be 11.7 and 12.0 nm by wide-angle and small-angle scattering respectively. Grain sub-division takes place throughout the irradiation and causes the collapse of the superlattice at high burnup. The bubble superlattice expands the U–Mo lattice and acts as strong sink for radiation-induced defects. The evolution of dislocation loops was, therefore, suppressed until the bubble superlattice collapsed.

  13. Determination of Mo in U-Mo alloy. EDTA volumetric method

    International Nuclear Information System (INIS)

    Wang Meiling; Wang Shu'an Hou Lieqi

    2005-10-01

    The determination methods of Mo are mentioned and EDTA volumetric method is proposed to determine the quantity of Mo in U-Mo alloy. According to the method, some condition experiments are done to confirm the quantity of some reagents. The results are satisfying. When the sample weight is 0.1-0.25 g, the precision is superior to 1% and the percent recovery is 99.2%-101.0%. (authors)

  14. Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

    International Nuclear Information System (INIS)

    Zadorozne, N.S.; Rebak, Raul B.

    2009-01-01

    P, may form if Ni-Cr-Mo alloys are exposed for tens of hours in the range of 600 C degrees to 1100 C degrees. These phases could have a detrimental effect upon corrosion resistance and cause a loss of mechanical ductility. The precipitation of TCP phases starts at grain boundaries and for long aging times it progresses to twins boundaries and then the grain bodies. TCP phases are rich in Mo and Cr. Zones in the matrix adjacent to the TCP precipitates may be depleted of Cr and Mo, and the alloy becomes sensitized.The aim of the present work was to compare the general corrosion rate and the crevice corrosion susceptibility of alloys C-22, C-22HS and HYBRID-BC1 in different metallurgical conditions when exposed to hot chloride solutions. The effects of the alloy composition and different heat treatments were assessed. (author)

  15. 99Mo production using MoO3 pellets obtained by mechanical compression and heat treatment

    International Nuclear Information System (INIS)

    Rojas, Jorge; Mendoza, Pablo; Lopez, Alcides

    2014-01-01

    This paper shows the results of the MoO 3 pellets fabrication by mechanical compression and the heat treatment method (MCHT) in order to optimize the production of 99 Mo in the RACSO Nuclear Center. The effects of polyvinyl alcohol (PVA) as binder are assessed by heat treatment of pellets in air atmosphere, evaluating the elimination process with increasing temperature and solubility in 5N NaOH. The results show that the pellets fabrication technique is suitable because fulfills the required technical specifications, allows to irradiate 50 % more of 98 Mo mass and facilitate a safer radiological handling of the irradiated MoO 3 . (authors).

  16. Friction and work function oscillatory behavior for an even and odd number of layers in polycrystalline MoS2.

    Science.gov (United States)

    Lavini, Francesco; Calò, Annalisa; Gao, Yang; Albisetti, Edoardo; Li, Tai-De; Cao, Tengfei; Li, Guoqing; Cao, Linyou; Aruta, Carmela; Riedo, Elisa

    2018-04-24

    A large effort is underway to investigate the properties of two-dimensional (2D) materials for their potential to become building blocks in a variety of integrated nanodevices. In particular, the ability to understand the relationship between friction, adhesion, electric charges and defects in 2D materials is of key importance for their assembly and use in nano-electro-mechanical and energy harvesting systems. Here, we report on a new oscillatory behavior of nanoscopic friction in continuous polycrystalline MoS2 films for an odd and even number of atomic layers, where odd layers show higher friction and lower work function. Friction force microscopy combined with Kelvin probe force microscopy and X-ray photoelectron spectroscopy demonstrates that an enhanced adsorption of charges and OH molecules is at the origin of the observed increase in friction for 1 and 3 polycrystalline MoS2 layers. In polycrystalline films with an odd number of layers, each crystalline nano-grain carries a dipole due to the MoS2 piezoelectricity, therefore charged molecules adsorb at the grain boundaries all over the surface of the continuous MoS2 film. Their displacement during the sliding of a nano-size tip gives rise to the observed enhanced dissipation and larger nanoscale friction for odd layer-numbers. Similarly, charged adsorbed molecules are responsible for the work function decrease in odd layer-number.

  17. Hot Extruded Polycrystalline Mg2Si with Embedded XS2 Nano-particles (X: Mo, W)

    Science.gov (United States)

    Bercegol, A.; Christophe, V.; Keshavarz, M. K.; Vasilevskiy, D.; Turenne, S.; Masut, R. A.

    2017-05-01

    Due to their abundant, inexpensive and non-toxic constituent elements, magnesium silicide and related alloys are attractive for large-scale thermoelectric (TE) applications in the 500-800 K temperature range, in particular for energy conversion. In this work, we propose a hot extrusion method favorable for large-scale production, where the starting materials (Mg2Si and XS2, X: W, Mo) are milled together in a sealed vial. The MoS2 nano-particles (0.5-2 at.%) act as solid lubricant during the extrusion process, thus facilitating material densification, as confirmed by density measurements based on Archimedes' method. Scanning electron microscopy images of bulk extruded specimens show a wide distribution of grain size, covering the range from 0.1 μm to 10 μm, and energy dispersive spectroscopy shows oxygen preferentially distributed at the grain boundaries. X-ray diffraction analysis shows that the major phase is the expected cubic structure of Mg2Si. The TE properties of these extruded alloys have been measured by the Harman method between 300 K and 700 K. Resistivity values at 700 K vary between 370 μΩ m and 530 μΩ m. The ZT value reaches a maximum of 0.26 for a sample with 2 at.% MoS2. Heat conductivity is reduced for extruded samples containing MoS2, which most likely behave as scattering centers for phonons. The reason why the WS2 particles do not bring any enhancement, for either densification or heat transfer reduction, might be linked to their tendency to agglomerate. These results open the way for further investigation to optimize the processing parameters for this family of TE alloys.

  18. Mo100 to Mo99 Target Cooling Enhancements Report

    Energy Technology Data Exchange (ETDEWEB)

    Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olivas, Eric Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mocko, Michal [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-16

    Target design requirements changed significantly over the past year to a much higher beam current on larger diameter disks, and with a beam impingement on both ends of the target. Scaling from the previous design, that required significantly more mass flow rate of helium coolant, and also thinner disks. A new Aerzen GM12.4 blower was selected that can deliver up to 400 g/s at 400 psi, compared to about 100 g/s possible with the Tuthill blower previously selected.Further, to accommodate the 42 MeV, 2.7 mA beam on each side of the target, the disk thickness and the coolant gaps were halved to create the current baseline design: 0.5 mm disk thickness (at 29 mm diameter) and 0.25 mm coolant gap. Thermal-hydraulic analysis of this target, presented below for reference, gave very good results, suggesting that the target could be improved with fewer, thicker disks and with disk thickness increasing toward the target center. The total thickness of Mo100 in the target remaining the same, that reduces the number of coolant gaps. This allows for the gap width to be increased, increasing the mass flow in each gap and consequently increasing heat transfer. A preliminary geometry was selected and analyzed with variable disk thickness and wider coolant gaps. The result of analysis of this target shows that disk thickness increase near the window was too aggressive and further resizing of the disks is necessary, but it does illustrate the potential improvements that are possible. Experimental and analytical study of diffusers on the target exit has been done. This shows modest improvement in requcing pressure drop, as will be summarized below. However, the benefit is not significant, and implementation becomes problematic when disk thickness is varying. A bull nose at the entrance does offer significant benefit and is relatively easy to incorporate. A bull nose on both ends is now a feature of the baseline design, and will be a feature of any redesign or enhanced designs that

  19. Applied thermodynamics: Grain boundary segregation

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Zheng, L.; Hofmann, S.; Šob, Mojmír

    2014-01-01

    Roč. 16, č. 3 (2014), s. 1462-1484 ISSN 1099-4300 R&D Projects: GA ČR(CZ) GAP108/12/0311; GA ČR GAP108/12/0144; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68378271 ; RVO:68081723 Keywords : interfacial segregation * Gibbs energy of segregation * enthalpy * entropy * volume * grain boundaries * iron Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.502, year: 2014

  20. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    Unknown

    ηηi has a value of unity inside the ith grain, decreases smoothly through the grain boundary region to zero out- side the grain. For a symmetric alloy of composition, c = 0⋅⋅5, our results show that microstructural evolution depends largely on the difference in the grain boundary energies, γγgb, of A-rich (αα) and B-rich (ββ) ...

  1. On the elastic stiffness of grain boundaries

    International Nuclear Information System (INIS)

    Zhang Tongyi; Hack, J.E.

    1992-01-01

    The elastic softening of grain boundaries is evaluated from the starting point of grain boundary energy. Several examples are given to illustrate the relationship between boundary energy and the extent of softening. In general, a high grain boundary energy is associated with a large excess atomic volume in the boundary region. The consequent reduction in grain boundary stiffness can represent a significant fraction of that observed in bulk crystals. (orig.)

  2. Conception, definition, measuring procedure of grain size

    International Nuclear Information System (INIS)

    Yanagisawa, Kazuaki

    1976-12-01

    The conception, definition, measuring procedure of ''Grain Size'' were surveyed. A concept ''grain diameter'' was introduced after deriving a calculation formula for the grain diameter for using the Comparison (simple) and Intercept(detailed) procedure. As an example and putting into practice, the grain diameter determination was carried out by means of the Comparison procedure for a UO 2 pellet used in a densification experiment. (auth.)

  3. Processing effects on core-shell grain formation in zirconium dioxide-modified barium titanate ceramics

    Science.gov (United States)

    Zhou, Lei

    2001-07-01

    Formation of core-shell grains in BaTiO3 based dielectric ceramics is essential to achieve stable dielectric temperature characteristic. This grain core-shell structure consists of a grain core, which is high purity BaTiO3, ferroelectric, and a paraelectric grain shell, where there is a concentration gradient of dopant. Most commonly core-shell additives are ZrO2, CeO2, Nb2O5+CO 2O3. As a result, internal stress is generated due to this dopant inhomogeneity within the grain and the normally sharp phase transition at Curie point becomes diffused. Up to now understanding and control of core-shell grains in BaTiO3 ceramics is still far from satisfying, which is the basis of this thesis work. In this work, processing influences on core-shell grain formation were investigated in the terms of powder size, stoichiometry, particle surface modification by slurry pH and leached Ba2+, pressing pressure and additive effects such as ZrO2, Nd2O3, BaO and flux CuO, BaCuO2, followed by multiple regression analysis to identify significant variables so as to form core-shell grains in a controller manner. It is found that ZrO2 amount; powder size, stoichiometry and temperature/time are most significant in control of core-shell characteristic (low Deltaepsilon% slurry pH; with adequate eutectic liquid phase, uniformly distributed fine grain morphology was achieved with high sintered densities. A dielectric formulation of 0.8˜1.3 wt% ZrO2, and 3 m/o BaCuO2 and 0.1˜0.3 m/o Nd2 O3 was successfully developed to be sintered at 1055˜1085°C/45˜90 min with Deltaepsilon% < 25%. This formulation has the potential to be co-fired with base metal electrodes.

  4. Effect of Transplanting Times on Rate and Duration of Grain Filling, Final Grain Weight and Grain Yield of Rice Cultivars

    Directory of Open Access Journals (Sweden)

    A. Vahdati-Rad

    2016-05-01

    Full Text Available In order to investigate the effects of temperature and radiation on rate and duration of grain filling and final grain weight in rice cultivars, a split plot experiment based on randomized complete block design with three replications was conducted at different transplanting times at the research field of University of Guilan, Rasht, Iran in 2013. Factors were: transplanting dates in main plots (5 May, 20 May and 5 June and rice cultivars (Hashemi, Ali Kazemi, Sangejo, Khazar, Dorfak and Gouhar in sub plots. The greatest grain weight (31.9 mg was obtained in Gouhar at 20 May and the smallest grain weight (20.4 mg was observed in Sangejo at 5 June transplanting dates. The longest effective filling period (32.9 days was achieved in Gouhar at 5 May transplanting date and the shortest grain filling duration (13.9 days was obtained in Hashemi. The greatest grain filling rate (1.62 mg day-1 was obtained in the Hashemi and the smallest rate (0.92 mg day-1 was observed in Gouhar. Significant correlations were observed between cumulative temperature and radiation with final grain weight (R = 0.689. There were significant and positive correlations between the cumulative temperature and irradiance with grain filling duration, in contrary to negative correlations with grain filling rate and grain filling period. The results of this experiment showed that the grain filling duration plays a greater role, than grain filling rate, in determination of the grain weight. It could be concluded that an early transplanting (5 May brings about favorable temperature and radiation conditions for an appropriate grain filling period and a greater final grain weight.

  5. Preferred carbon precursors for lipid labelling in the heterotrophic endosperm of developing oat (Avena sativa L.) grains.

    Science.gov (United States)

    Grimberg, Åsa

    2014-10-01

    Oat (Avena sativa L.) is unusual among the cereal grains in storing high amounts of oil in the endosperm; up to 90% of total grain oil. By using oat as a model species for oil metabolism in the cereal endosperm, we can learn how to develop strategies to redirect carbon from starch to achieve high-oil yielding cereal crops. Carbon precursors for lipid synthesis were compared in two genetically close oat cultivars with different endosperm oil content (about 6% and 10% of grain dw, medium-oil; MO, and high-oil; HO cultivar, respectively) by supplying a variety of (14)C-labelled substrates to the grain from both up- and downstream parts of glycolysis, either through detached oat panicles in vitro or by direct injection in planta. When supplied by direct injection, (14)C from acetate was identified to label the lipid fraction of the grain to the highest extent among substrates tested; 46% of net accumulated (14)C, demonstrating its applicability as a marker for lipids in the endosperm. Time course analyses of injected (14)C acetate during grain development suggested a more efficient transfer of fatty acids from polar lipids to triacylglycerol in the HO as compared to the MO cultivar, and turnover of triacylglycerol was suggested to not play a major role for the final oil content of oat grain endosperm despite the low amount of protective oleosins in this tissue. Moreover, availability of light was shown to drastically affect grain net carbon accumulation from (14)C-sucrose when supplied through detached panicles for the HO cultivar. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  6. Microstructural defects modeling in the Al-Mo system

    International Nuclear Information System (INIS)

    Pascuet, Maria I.; Fernandez, Julian R.; Monti, Ana M.

    2006-01-01

    In this work we have utilized computer simulation techniques to study microstructural defects, such as point defects and interfaces, in the Al-Mo alloy. Such alloy is taken as a model to study the Al(fcc)/U-Mo(bcc) interface. The EAM interatomic potential used has been fitted to the formation energy and lattice constant of the AlMo 3 intermetallic. Formation of vacancies for both components Al and Mo and anti-sites, Al Mo and Mo Al , as well as vacancy migration was studied in this structure. We found that the lowest energy defect complex that preserves stoichiometry is the antisite pair Al Mo +Mo Al , in correspondence with other intermetallics of the same structure. Our results also suggest that the structure of the Al(fcc)/Mo(bcc) interface is unstable, while that of the Al(fcc)/Al 5 Mo interface is stable, as observed experimentally. (author) [es

  7. Transient Solute Drag in Migrating Grain Boundaries

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Fischer, F. D.; Liendl, M.

    2011-01-01

    Roč. 59, č. 17 (2011), s. 6556-6562 ISSN 1359-6454 R&D Projects: GA MŠk(CZ) OC10029 Institutional research plan: CEZ:AV0Z20410507 Keywords : Grain boundary diffusion * Grain boundary migration * Grain boundary segregation Subject RIV: BJ - Thermodynamic s Impact factor: 3.755, year: 2011

  8. Bioactive compounds in whole grain wheat

    NARCIS (Netherlands)

    Mateo Anson, N.

    2010-01-01

    Bread can be healthier! Consuming whole-grain foods can prevent cardiovascular diseases, type-2 diabetes and metabolic syndrome. This is due to bioactive compounds in whole grain, such as antioxidants and anti-inflammatory compounds. We found that the different fractions of a wheat grain vary much

  9. Traditional grains boost nutrition in rural India

    International Development Research Centre (IDRC) Digital Library (Canada)

    will work together to grow and test hardy and highly nutritious grains, including several varieties of millets, grain amaranth, and associated legumes. Researchers ... security of small-farm families. • Reduced physical labour for women through improved grain-processing equipment. • Improved environmental sustainability on ...

  10. Determination of grain boundary geometry using TEM

    NARCIS (Netherlands)

    Jang, H.; Farkas, D.; Hosson, J.T.M. De

    An experimental method to obtain the grain boundary geometry using the transmission electron microscope is presented. The method allows Σ determination including grain boundary plane orientation. In order to determine the specialness of the grain boundary, three different criteria for maximum

  11. Structure and chemistry of the sorghum grain

    Science.gov (United States)

    Sorghum is grown around the world and often under harsh and variable environmental conditions. Combined with the high degree of genetic diversity present in sorghum, this can result in substantial variability in grain composition and grain quality. While similar to other cereal grains such as maize ...

  12. Study on soft magnetic properties of Finemet-type nanocrystalline alloys with Mo substituting for Nb

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Dehui; Zhou, Bingwen; Jiang, Boyu; Ya, Bin; Zhang, Xingguo [School of Materials Science and Engineering, Dalian University of Technology, Dalian (China)

    2017-10-15

    The thermal stability, microstructure, and soft magnetic properties as a function of annealing time were studied for Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 3-x}Mo{sub x} (x = 0, 1, 2, 3) (atom percent, at.%,) ribbons. It was found that substituting Nb by Mo reduced the thermal stability. After 15 min short time vacuum annealing, Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 2}Mo{sub 1} and Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 1}Mo{sub 2} samples obtained higher permeability and similar coercivity compared to the original Finemet alloy (Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 3}), Mo substituting Nb reduced the optimum annealing time in Finemet-type alloys, and meanwhile marginally increased the saturation magnetization. Substituting all Nb by Mo led to the earlier formation of non-soft magnetic phase, thus deteriorated the soft magnetic properties. XRD and TEM structural analysis showed that in Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 2}Mo{sub 1} and Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 1}Mo{sub 2} samples (annealed for 15 min), nanocrystals ∝10 nm in size were obtained, and the good soft magnetic properties of these alloys could be attributed to the small grain size. The relationship between annealing time, soft magnetic properties, and microstructure was established. Reducing annealing time and temperature to obtain best soft magnetic properties could cut down the production costs of Finemet-type alloys. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Orientation dependence of grain-boundary energy in metals in the view of a pseudoheterophase dislocation core model

    International Nuclear Information System (INIS)

    Missol, W.

    1976-01-01

    A new dislocation model for symmetric tilt grain boundaries was developed as a basis for deriving the quantitative dependence of grain-boundary energy upon misorientation angle in the form of an expression similar to that given by Read and Shockley [Phys. Rev. 78: 275(1950)]. The range of applicability of this equation was extended to over 20 degrees. A comparison of theory and experiment was made for Bi, Ag, Cu, and Fe--Si 3 percent in the teen-degree range of misorientation angles and for Au, α-Fe, Mo, and W in the high-angle range

  14. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2017-04-01

    Full Text Available A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS NiMo-based alloys containing varying amounts of SiC (0.5–2.5 wt % were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA route followed by spark plasma sintering (SPS and rapid cooling. Neutron Powder Diffraction (NPD, Electron Back Scattering Diffraction (EBSD, and Transmission Electron Microscopy (TEM were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni3Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo2C particles during sintering. The amount of grain boundaries greatly increases the Hall–Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

  15. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy

    Science.gov (United States)

    Yang, Chao; Muránsky, Ondrej; Zhu, Hanliang; Thorogood, Gordon J.; Avdeev, Maxim; Huang, Hefei; Zhou, Xingtai

    2017-01-01

    A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS) NiMo-based alloys containing varying amounts of SiC (0.5–2.5 wt %) were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA) route followed by spark plasma sintering (SPS) and rapid cooling. Neutron Powder Diffraction (NPD), Electron Back Scattering Diffraction (EBSD), and Transmission Electron Microscopy (TEM) were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni3Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo2C particles during sintering. The amount of grain boundaries greatly increases the Hall–Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process. PMID:28772747

  16. Hormonal changes in the grains of rice subjected to water stress during grain filling.

    Science.gov (United States)

    Yang, J; Zhang, J; Wang, Z; Zhu, Q; Wang, W

    2001-09-01

    Lodging-resistant rice (Oryza sativa) cultivars usually show slow grain filling when nitrogen is applied in large amounts. This study investigated the possibility that a hormonal change may mediate the effect of water deficit that enhances whole plant senescence and speeds up grain filling. Two rice cultivars showing high lodging resistance and slow grain filling were field grown and applied with either normal or high amount nitrogen (HN) at heading. Well-watered and water-stressed (WS) treatments were imposed 9 days post anthesis to maturity. Results showed that WS increased partitioning of fixed (14)CO(2) into grains, accelerated the grain filling rate but shortened the grain filling period, whereas the HN did the opposite way. Cytokinin (zeatin + zeatin riboside) and indole-3-acetic acid contents in the grains transiently increased at early filling stage and WS treatments hastened their declines at the late grain filling stage. Gibberellins (GAs; GA(1) + GA(4)) in the grains were also high at early grain filling but HN enhanced, whereas WS substantially reduced, its accumulation. Opposite to GAs, abscisic acid (ABA) in the grains was low at early grain filling but WS remarkably enhanced its accumulation. The peak values of ABA were significantly correlated with the maximum grain filling rates (r = 0.92**, P water stress during grain filling, especially a decrease in GAs and an increase in ABA, enhances the remobilization of prestored carbon to the grains and accelerates the grain filling rate.

  17. Computer simulation of grain growth in HAZ

    Science.gov (United States)

    Gao, Jinhua

    Two different models for Monte Carlo simulation of normal grain growth in metals and alloys were developed. Each simulation model was based on a different approach to couple the Monte Carlo simulation time to real time-temperature. These models demonstrated the applicability of Monte Carlo simulation to grain growth in materials processing. A grain boundary migration (GBM) model coupled the Monte Carlo simulation to a first principle grain boundary migration model. The simulation results, by applying this model to isothermal grain growth in zone-refined tin, showed good agreement with experimental results. An experimental data based (EDB) model coupled the Monte Carlo simulation with grain growth kinetics obtained from the experiment. The results of the application of the EDB model to the grain growth during continuous heating of a beta titanium alloy correlated well with experimental data. In order to acquire the grain growth kinetics from the experiment, a new mathematical method was developed and utilized to analyze the experimental data on isothermal grain growth. Grain growth in the HAZ of 0.2% Cu-Al alloy was successfully simulated using the EDB model combined with grain growth kinetics obtained from the experiment and measured thermal cycles from the welding process. The simulated grain size distribution in the HAZ was in good agreement with experimental results. The pinning effect of second phase particles on grain growth was also simulated in this work. The simulation results confirmed that by introducing the variable R, degree of contact between grain boundaries and second phase particles, the Zener pinning model can be modified as${D/ r} = {K/{Rf}}$where D is the pinned grain size, r the mean size of second phase particles, K a constant, f the area fraction (or the volume fraction in 3-D) of second phase.

  18. Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

    International Nuclear Information System (INIS)

    Kumar, Arvind; Verma, G.S.P.

    1975-01-01

    Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber. (author)

  19. DFT study of the reactions of Mo and Mo with CO2 in gas phase

    Indian Academy of Sciences (India)

    Abstract. Density functional theory (DFT) calculations have been performed to explore the potential energy surfaces of C–O bond activation in CO2 molecule by gas-phase Mo. + cation and Mo atom, in order to better understanding the mechanism of second-row metal reacting with CO2. The minimum energy reaction path is.

  20. DFT study of the reactions of Mo and Mo with CO 2 in gas phase

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 3. DFT study of the reactions of Mo and Mo+ with CO2 in gas phase. Deman Han Guoliang Dai Hao Chen Hua Yan Junyong Wu Chuanfeng Wang Aiguo Zhong. Volume 123 Issue 3 May 2011 pp 299-309 ...

  1. Grain storage at farm and warehouses level

    Directory of Open Access Journals (Sweden)

    Neacşu, A. N.

    2010-12-01

    Full Text Available Grain storage is very important because the quality of flour obtained from grain will be found in the finished products’ quality. Grains must be stored in well established conditions regarding temperature, humidity, airflow, trying to avoid the risk of being attacked by rodents and insects. If these conditions are not complied with, some qualitative deficits of the grains - such as mould at pH, infestation, fermentation etc. - may appear. The storage methods are those responsible for maintaining a good quality of the grains.

  2. 3D modeling of metallic grain growth

    Energy Technology Data Exchange (ETDEWEB)

    George, D.; Carlson, N.; Gammel, J.T.; Kuprat, A.

    1999-06-01

    This paper will describe simulating metallic grain growth using the Gradient Weighted Moving Finite Elements code, GRAIN3D. The authors also describe the set of mesh topology change operations developed to respond to changes in the physical topology such as the collapse of grains and to maintain uniform calculational mesh quality. Validation of the method is demonstrated by comparison to analytic calculations. The authors present results of multigrain simulations where grain boundaries evolve by mean curvature motion and include results which incorporate grain boundary orientation dependence.

  3. Cd3(MoO4)(TeO3)2: A Polar 3D Compound Containing d10-d0 SCALP-Effect Cations.

    Science.gov (United States)

    Feng, Yuquan; Fan, Huitao; Zhong, Zhiguo; Wang, Hongwei; Qiu, Dongfang

    2016-11-21

    The new polar 3D cadmium molybdotellurite Cd 3 (MoO 4 )(TeO 3 ) 2 was obtained by means of a high-temperature solid-state method. Cd 3 (MoO 4 )(TeO 3 ) 2 is a monoclinic crystal system, and it exhibits the polar space group P2 1 (No. 4). The structure of Cd 3 (MoO 4 )(TeO 3 ) 2 can be viewed as a complicated 3D architecture that is composed of distorted CdO n (n = 6, 7) polyhedra, TeO 3 trigonal pyramids, and MoO 4 polyhedra. The compound features the first 3D NCS cadmium molybdotellurite with 1D 4- and 6-MR channels and a polar structure originating from the TeO 3 groups, MoO 4 groups, and displacements of d 10 Cd 2+ cations. The results were further confirmed by calculations of the net polarization. The UV-vis spectrum and thermal properties indicate that Cd 3 (MoO 4 )(TeO 3 ) 2 exhibits a broad transparent region and excellent thermal stability. SHG tests of Cd 3 (MoO 4 )(TeO 3 ) 2 revealed that its response is approximately the same as that of KH 2 PO 4 at the same grain size between 105 and 150 μm and that it is phase-matchable.

  4. Grain boundary corrosion of copper canister material

    International Nuclear Information System (INIS)

    Fennell, P.A.H.; Graham, A.J.; Smart, N.R.; Sofield, C.J.

    2001-03-01

    The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister. The potential for grain boundary corrosion was investigated by exposing copper specimens, which had undergone different heat treatments and hence had different grain sizes, to aerated artificial bentonite-equilibrated groundwater with two concentrations of chloride, for increasing periods of time. The degree of grain boundary corrosion was determined by atomic force microscopy (AFM) and optical microscopy. AFM showed no increase in grain boundary 'ditching' for low chloride groundwater. In high chloride groundwater the surface was covered uniformly with a fine-grained oxide. No increases in oxide thickness were observed. No significant grain boundary attack was observed using optical microscopy either. The work suggests that in aerated artificial groundwaters containing chloride ions, grain boundary corrosion of copper is unlikely to adversely affect SKB's copper canisters

  5. Photo- and Electrochromic Properties of Activated Reactive Evaporated MoO3 Thin Films Grown on Flexible Substrates

    Directory of Open Access Journals (Sweden)

    K. Hari Krishna

    2008-01-01

    Full Text Available The molybdenum trioxide (MoO3 thin films were grown onto ITO-coated flexible Kapton substrates using plasma assisted activated reactive evaporation technique. The film depositions were carried out at constant glow power and oxygen partial pressures of 8 W and 1×10−3 Torr, respectively. The influence of substrate temperature on the microstructural and optical properties was investigated. The MoO3 thin films prepared at a substrate temperature of 523 K were found to be composed of uniformly distributed nanosized grains with an orthorhombic structure of α-MoO3. These nanocrystalline MoO3 thin films exhibited higher optical transmittance of about 80% in the visible region with an evaluated optical band gap of 3.29 eV. With the insertion of 12.5 mC/cm2, the films exhibited an optical modulation of 40% in the visible region with coloration efficiency of 22 cm2/C at the wavelength of 550 nm. The MoO3 films deposited at 523 K demonstrated better photochromic properties and showed highest color center concentration for the irradiation time of 30 minutes at 100 mW/cm2.

  6. Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

    KAUST Repository

    Lu, Chun-I

    2017-07-21

    This report presents a series of low-temperature (4.5 K) scanning tunneling microscopy and spectroscopy experimental results on monolayer MoS2 deposited on highly oriented pyrolytic graphite using chemical vapor deposition. To reveal the detailed connection between atomic morphology and conductivity in twisted MoS2/graphite heterojunctions, we employ high-sensitivity tunneling spectroscopy measurements by choosing a reduced tip-sample distance. We discern previously unobserved conductance peaks within the band gap range of MoS2, and by comparing the tunneling spectra from MoS2 grains of varying rotation with respect to the substrate, show that these features have small but non-negligible dependence on the moiré superstructure. Furthermore, within a single moiré supercell, atomically resolved tunneling spectroscopy measurements show that the spectra between the moiré high and low areas are also distinct. These in-gap states are shown to have an energy shift attributed to their local lattice strain, matching corresponding behavior of the conduction band edge, and we therefore infer that these features are intrinsic to the density of states, rather than experimental artifacts, and attribute them to the twisted stacking and local strain energy of the MoS2/graphite heterointerface.

  7. Investigation of structural transition in molybdates CuMo1-xWxO4 prepared by polymeric precursor method

    Directory of Open Access Journals (Sweden)

    Mohamed Benchikhi

    2017-03-01

    Full Text Available Solid solutions (CuMo1-xWxO4 where 0 ≤ x ≤ 0.12 were synthesized by using a polymeric precursor method. The crystallization process of the polymeric precursors was investigated using TG-DTA, FTIR and XRD techniques. Crystallization of the CuMo1-xWxO4 powders was detected at 300 °C, and entirely completed at 420 °C. XRD patterns revealed that the polymorphic variety was dependent upon the tungsten content. For x ≤ 0.075, the solid solutions were isostructural to α-CuMoO4 whereas, for 0.075 < x ≤ 0.12, they were isostructural to γ-CuMoO4. The obtained homogeneous powders are constituted of relatively spherical grains with sizes in the range 0.5–2.0 µm. The phase transition of the as-synthesized CuMo1-xWxO4 powders was investigated by X-ray diffraction at elevated temperature and dilatometry. The temperature of the structural transition γ → α during heating was dependent upon the tungsten content.

  8. Synthesis, surface structure and optical properties of double perovskite Sr{sub 2}NiMoO{sub 6} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei; Wan, Yingpeng [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 (China); Xie, Hongde, E-mail: xiehongde@suda.edu.cn [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 (China); Huang, Yanlin; Yang, Li [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 (China); Qin, Lin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan, 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan, 608-737 (Korea, Republic of)

    2016-12-15

    Highlights: • Double perovskite Sr{sub 2}NiMoO{sub 6} nanoparticles were prepared via sol-gel route. • The nanoparticles have efficient optical absorption in visible light. • The band structure and energy positions were determined. • The perovskite has efficient photocatalytic on RhB photodegradation. • Multivalent Mo and Ni-ions on the surfaces were investigated. - Abstract: Double perovskite Sr{sub 2}NiMoO{sub 6} nanoparticles were synthesized via the chemical sol-gel route. The phase formation was investigated through X-ray polycrystalline diffraction (XRD) and Rietveld refinements. The perovskite crystallized in worm-like nano-grains with the diameter of 20–50 nm. The optical properties were measured by the optical absorption spectra. The nanoparticles present an indirect allowed transition with a narrow band gap of 2.1 eV. Sr{sub 2}NiMoO{sub 6} nanoparticles have obvious photocatalytic ability on the degradation of Rhodamine B (RhB) solutions under the irradiation of visible light. The transport behaviors of the excitons were investigated from the photoluminescence spectra and the corresponding decay lifetimes. Sr{sub 2}NiMoO{sub 6} nanoparticles present several advantages for photocatalysis such as the appropriate band energy positions, the quenched luminescence, and the coexistence of multivalent ions in the lattices.

  9. Whole grains and health: from theory to practice--highlights of The Grains for Health Foundation's Whole Grains Summit 2012.

    Science.gov (United States)

    McKeown, Nicola M; Jacques, Paul F; Seal, Chris J; de Vries, Jan; Jonnalagadda, Satya S; Clemens, Roger; Webb, Densie; Murphy, Lee Anne; van Klinken, Jan-Willem; Topping, David; Murray, Robyn; Degeneffe, Dennis; Marquart, Leonard F

    2013-05-01

    The Grains for Health Foundation's Whole Grains Summit, held May 19-22, 2012 in Minneapolis, was the first meeting of its kind to convene >300 scientists, educators, food technologists, grain breeders, food manufacturers, marketers, health professionals, and regulators from around the world. Its goals were to identify potential avenues for collaborative efforts and formulate new approaches to whole-grains research and health communications that support global public health and business. This paper summarizes some of the challenges and opportunities that researchers and nutrition educators face in expanding the knowledge base on whole grains and health and in translating and disseminating that knowledge to consumers. The consensus of the summit was that effective, long-term, public-private partnerships are needed to reach across the globe and galvanize the whole-grains community to collaborate effectively in translating whole-grains science into strategies that increase the availability and affordability of more healthful, grain-based food products. A prerequisite of that is the need to build trust among diverse multidisciplinary professionals involved in the growing, producing, marketing, and regulating of whole-grain products and between the grain and public health communities.

  10. Magnetic Property and Microstructure of Melt-Spun (Ndcentre dotDy)-(Fe{center_dot}Co{center_dot}Al{center_dot}M)-B ribbon (M:Sn, Mo)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, ByungChul; KangKiWon [Korea Atomic Energy Research Inst., Daeduk (Korea, Republic of); Yeo, JungSoo; Song, JinTae [Hanyang Univ., Seoul (Korea, Republic of)

    1997-04-01

    The microstructures, temperature stability and magnetic properties of melt-spun (Nd{center_dot}Dy)-(Fe{center_dot}Co{center_dot}Al)-B ribbons with the addition of Sn and Mo were studied. The addition of Sn and Mo greatly increased the Curie temperature of (Nd{center_dot}Dy)-(Fecentre dotCo{center_dot}Al)-B ribbon and improved magnetic properties, especially the coercivity over 1 KOe. It was considered that disturbed grain boundary, a kind of defects of the grain boundary region, could be observed along the grain boundaries by HREM(high resolution electron microscopy) which seemed to be responsible for the marked improvement of coercivity. Also, the additive element of Sn and Mo decreased the irreversible loss to 3% and 6%, respectively and improved the temperature stability of the ribbons. It seemed that the additions of Sn and Mo were resulted in higher coercivity. A linear relationship was found between HRT(heat resistance temperature)of (Ndcentre dotDy)-(Fe{center_dot}Co{center_dot}Al{center_dot}M)-B ribbons and irreversible loss (author). 14 refs.15 figs.

  11. Vedinių su priesaga *-mo- raida

    Directory of Open Access Journals (Sweden)

    Saulius Ambrazas

    2011-12-01

    Full Text Available DEVELOPMENT OF DERIVATIVES WITH THE SUFFIX *-mo-SummaryAdjectives with the suffix *-mo- have been formed from substantives (cf. Lith. tólimas / tólymas and Latv. dial. tuôl’eims ‘distant’; Pruss. *auktimas ‘high’; Skr. agrimá- ‘the first, who is at the head’ and verbs (cf. Lith. dial. ãpsukmas ‘sewn round’, pliùkšmas ‘deflated, limp’; OLith. laimas ‘happy’ and Pruss. etnīstislaims (gnadenreich III 631; Lith. liñksmas and Latv. lìksms ‘merry, gay, joyfull’, Gmc. *werma- ‘warm’, Skr. bhīmá- ‘terrible, frightfull’, Toch. A, B cämpamo- ‘well-to-do, rich’, Hitt. kišamma- ‘combed’ from the Late Proto-Indo-European. The gratest part of them became participles in the Baltic, Slavic and Albanian languages.On the other hand, the use of derivatives with the suffix *-mo- in the position of abstract nouns is also very old, cf. semanticaly concretized and derivationaly indissoluble abstract noun, in herited from Proto-Indo-European, Lith. dmas (dmai, Latv. dũmi, Pruss. dumis (rauch E 39, Slav. *dymъ, Latv. fūmus, Skr. dhūmó- ‘smoke’ and Gk. θῡ‑μός with abstract meaning ‘soal, vitality, passion,    need’ : dhe-/dh-/dhū- ‘blow; breathe; choke; smoke; rush; disperse; whirl, move, stir’.In the East Baltic languages abstract nouns with the derived suffixes, based on *-mo-, became productive, cf. nomina actionis with *-i-mo- in Lithuanian (cf. gyvẽnimas ‘life’ and corresponding derivatives with *-u-mo- in Latvian (cf. ìeradums ‘custom, habit’.

  12. Effect of Welding Processes on the Microstructure, Mechanical Properties and Residual Stresses of Plain 9Cr-1Mo Steel Weld Joints

    Science.gov (United States)

    Nagaraju, S.; Vasantharaja, P.; Brahadees, G.; Vasudevan, M.; Mahadevan, S.

    2017-12-01

    9Cr-1Mo steel designated as P9 is widely used in the construction of power plants and high-temperature applications. It is chosen for fabricating hexcan fuel subassembly wrapper components of fast breeder reactors. Arc welding processes are generally used for fabricating 9Cr-1Mo steel weld joints. A-TIG welding process is increasingly being adopted by the industries. In the present study, shielded metal arc (SMA), tungsten inert gas (TIG) and A-TIG welding processes are used for fabricating the 9Cr-1Mo steel weld joints of 10 mm thickness. Effect of the above welding processes on the microstructure evolution, mechanical properties and residual stresses of the weld joints has been studied in detail. All the three weld joints exhibited comparable strength and ductility values. 9Cr-1Mo steel weld joint fabricated by SMAW process exhibited lower impact toughness values caused by coarser grain size and inclusions. 9Cr-1Mo steel weld joint fabricated by TIG welding exhibited higher toughness due to finer grain size, while the weld joint fabricated by A-TIG welding process exhibited adequate toughness values. SMA steel weld joint exhibited compressive residual stresses in the weld metal and HAZ, while TIG and A-TIG weld joint exhibited tensile residual stresses in the weld metal and HAZ.

  13. DEVELOPMENT OF GRAIN MARKET IN UKRAINE

    Directory of Open Access Journals (Sweden)

    Aleksandr Maslak

    2015-11-01

    Full Text Available The subject of the research is a set of theoretical, methodological and practical fundamentals of organizational and economic functioning are integrated agricultural formations in the grain market of Ukraine. The methodological basis of research is the complex analysis of economic processes in the grain market in Ukraine and the world. During research we used such methods as method of systematization and comparison, statistic, economic, balance, constructive, target-oriented, and the methods of induction and deduction, analogy and comparison. Main aim of this article is the analysis of the situation on the grain market in Ukraine, defining the role of integrated agricultural formations in this market, improving the organizational-economic mechanism of its functioning, identifies ways of improving the competitiveness of Ukraine among world exporters of grain. Using results of the studies we examined trends grain market in Ukraine; influence of businesses in grain production; analysis of constraints to improve production efficiency of grain; defined domestic (internal needs of grain in Ukraine; assessed the status and expediency transformation infrastructure of the grain market of Ukraine; defined priority directions of development of the grain market in Ukraine. As a result of the preparation of articles, it is obtained the following conclusions: Ukraine is the world's largest producers and exporters of grain, the production of integrated agricultural units to a third of the total grain; technical condition of farm does not meet the needs of production; the domestic market is unable to provide the existing demand for grain production, contributing to export growth; Ukraine has a number of problems due to increased grain production, namely the shortage of storage capacity for the storage of grain, limited performance transshipment of grain in port elevators and imperfection and depreciation of transport systems; solving the existing problems is

  14. Coarse-graining complex dynamics

    DEFF Research Database (Denmark)

    Sibani, Paolo

    2013-01-01

    Continuous Time Random Walks (CTRW) are widely used to coarse-grain the evolution of systems jumping from a metastable sub-set of their configuration space, or trap, to another via rare intermittent events. The multi-scaled behavior typical of complex dynamics is provided by a fat-tailed distribu......Continuous Time Random Walks (CTRW) are widely used to coarse-grain the evolution of systems jumping from a metastable sub-set of their configuration space, or trap, to another via rare intermittent events. The multi-scaled behavior typical of complex dynamics is provided by a fat...... macroscopic variables all produce identical long time relaxation behaviors. Hence, CTRW shed no light on the link between microscopic and macroscopic dynamics. We then highlight how a more recent approach, Record Dynamics (RD) provides a viable alternative, based on a very different set of physical ideas......: while CTRW make use of a renewal process involving identical traps of infinite size, RD embodies a dynamical entrenchment into a hierarchy of traps which are finite in size and possess different degrees of meta-stability. We show in particular how RD produces the stretched exponential, power...

  15. Spektroskopie a spektroelektrochemie MoS2

    OpenAIRE

    Jurková, Kateřina

    2014-01-01

    This work deals with studies MoS2 layers prepared by mechanical exfoliation was detected by optical microscopy and the number of layers was determined from AFM measurement. The layers were characterized by Raman spectroscopy in various wavelengths. A spectroelectrochemical cell for the sandwich sample consisting of a MoS2 layer and two layers of graphene with various isotope composition and Raman spectra measurements were performed at voltages from 0.0 V to 0.9 V. A larger shift of the G band...

  16. mo encontrar patentes, setiembre 2010

    OpenAIRE

    Bonich, Mònica; Cervera-Farré, Albert; Santos-Hermosa, Gema

    2010-01-01

    Com es poden trobar les patents: què són les patents?, què es pot patentar?, qui assigna les patents? i com es poden trobar patents? Cómo encontrar patentes: ¿qué son las patentes?, ¿qué se puede patentar?, ¿quién asigna las patentes? y ¿cómo se pueden encontrar patentes? How to find patents: what are patents?, what can be patented?, who awards the patents? and how can patents be found?

  17. Elevated Temperature Tensile Tests on DU–10Mo Rolled Foils

    Energy Technology Data Exchange (ETDEWEB)

    Schulthess, Jason [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    Tensile mechanical properties for uranium-10 wt.% molybdenum (U–10Mo) foils are required to support modeling and qualification of new monolithic fuel plate designs. It is expected that depleted uranium-10 wt% Mo (DU–10Mo) mechanical behavior is representative of the low enriched U–10Mo to be used in the actual fuel plates, therefore DU-10Mo was studied to simplify material processing, handling, and testing requirements. In this report, tensile testing of DU-10Mo fuel foils prepared using four different thermomechanical processing treatments were conducted to assess the impact of foil fabrication history on resultant tensile properties.

  18. Study on grain growth of fine grained WC-Co hardmetal by numerical calculation

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, N. [Kobe Steel, Ltd., Kobe (Japan); Hayashi, K. [The University of Tokyo, Tokyo (Japan). Institute of industrial Science

    2000-12-15

    This paper reviews our simulation study by numerical calculation based on two-, three- and multi-grain-size models on WC grain growth in fine grained WC-Co hardmetal doped with VC. The study aimed to presume or predict the following: (1) the cause and conditions for the abnormal grain growth which occurs in some cases in the fine grained hardmetal prepared from fine WC powders with mean grain size below about 0.2{mu}m, and (2) how the mean grain size of the hardmetal varies with decreasing mean grain size of the WC starting powder to 0.1 pm or nano-meter size. The calculation results by these three kinds of models suggested the following, respectively: (1) the occurrence of the abnormal grain growth is generally substantial for WC starting powder with bimodal size-distribution and mean gram size below 0.1 - 0.2{mu}m, and not due to the non-uniform distribution of the grain growth inhibitor, (2) the introduction of middle grains caused the disappearance of small (fine) grains during sintering, leading to abruptly increase of the mean grain size of alloy, and (3) the mean grain size of alloy becomes so large as about 0.3 - 0.4{mu}m, even when the WC starting powders with nano-size as well as 0.1 {mu}m are used. (author)

  19. Oscillatory behavior of the magnetic properties of Nd–Fe–B films with Mo and Mo–Cu additions

    International Nuclear Information System (INIS)

    Urse, M.; Grigoras, M.; Lupu, N.; Borza, F.; Chiriac, H.

    2013-01-01

    A series of Ta/NdFeB/Ta thin films with Mo and Mo–Cu additions embedded by alloying and by stratification have been prepared by r.f. sputtering. The influence of additions, their embedding mode, and annealing temperature on the structural and magnetic behavior of Ta/NdFeB/Ta thin films is presented. The use of additions of Mo and Mo–Cu leads to refined grain structure and improvement in the hard magnetic characteristics of Ta/NdFeB/Ta thin films. The Ta/[NdFeBMo(540 nm)/Ta films and Ta/[NdFeB(180 nm)/MoCu(dnm)] × n/Ta multilayer films present enhanced coercivities and M r /M s ratios in comparison with the Ta/NdFeB(540 nm)/Ta films. The stratification of Ta/NdFeB/Ta thin films with Mo–Cu interlayers leads to an oscillatory behavior of hard magnetic characteristics of the Ta/[NdFeB(180 nm)/MoCu(dnm)] × n/Ta multilayer films, when the thickness, d, of Mo–Cu interlayers varies by increments of 1 nm. When the thickness of Mo–Cu interlayers varies by increments of 2 nm the oscillatory behavior of the magnetic characteristics is not revealed. For a thickness of the Mo–Cu interlayer of 3 nm in the Ta/[NdFeB(180 nm)/MoCu(3 nm)] × 3/Ta thin films annealed at 650 °C, the c-axis of part of the hard magnetic Nd 2 Fe 14 B grains is oriented out-of-plane

  20. Determination of crystallization as a function of Mo layer thickness in Mo/Si multilayers

    DEFF Research Database (Denmark)

    Abdali, Salim; Gerward, Leif; Yakshin, A.E.

    2002-01-01

    information on the crystalline phases, average size and crystallite formation. Comparison of these parameters for the samples examined provided novel results, especially regarding the in-plane and in-depth average sizes of the crystallites. The most important result is that crystallization takes place already......Mo/Si multilayer samples with different Mo layer thickness were deposited by electron beam evaporation, while Kr+ ions (300 eV) were used for polishing the Si layers. Crystallization as a function of the Mo layer thickness deposited was investigated by grazing incidence X-ray diffraction, giving...

  1. Isothermal and Two-Temperature Zone Selenization of Mo Layers

    Directory of Open Access Journals (Sweden)

    L. Kaupmees

    2012-01-01

    Full Text Available Glass/Mo, Mo foil, glass/Mo/In, and glass/Mo/Cu stacked layers were selenized in closed vacuum tubes by isothermal and/or two-temperature zone annealing in Se vapors. The selenization process was studied dependent on Se vapor pressure, temperature and time. Samples were selenized from 375 to 580°C for 30 and 60 minutes. The applied Se pressure was varied between 130 and 4.4⋅103 Pa. The increase of MoSe2 film thickness was found to depend on the origin of Mo. MoSe2 thickness dL on Mo-foil was much higher than on sputtered Mo layers, and it depended linearly on time and as a power function dL~PSe1/2 on Se vapor pressure. The residual oxygen content in the formed MoSe2 layers was much lower in the two-zone selenization process. If Mo was covered with Cu or In before selenization, these were found to diffuse into formed MoSe2 layer. All the MoSe2 layers showed p-type conductivity.

  2. Van de Graaff Experiments: Mo Redox Chemistry and Iodine Speciation

    Energy Technology Data Exchange (ETDEWEB)

    Youker, A. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Krebs, J. F. [Argonne National Lab. (ANL), Argonne, IL (United States); Hebden, A. [Argonne National Lab. (ANL), Argonne, IL (United States); Quigley, K. [Argonne National Lab. (ANL), Argonne, IL (United States); Stepinski, D. [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, G. F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2012-09-27

    Argonne National Laboratory (Argonne) is assisting Morgridge Institute for Research (MIR) in its efforts to develop SHINE, which is an accelerator-driven process that will use a uranyl-sulfate solution for the production of Mo-99. Mo will be separated from an irradiated uranyl-sulfate solution using a titania sorbent; however, the highly reducing environment may lead to Mo reduction. If Mo is reduced to Mo(IV) or Mo(V), its adsorption and/or recovery will decrease, and an oxidizing agent will be required to ensure that Mo is present as Mo(VI). Another concern for SHINE is related to the speciation of iodine during irradiation, cooling, column loading and stripping, and Mo-99 purification. Both Mo oxidation state and iodine speciation experiments were performed using a Van de Graaff generator as a source of radiation. Initial results indicate that Mo may be reduced during irradiation because low Mo recoveries were obtained for three separate column experiments performed using irradiated solutions. The results were complicated, however, because nearly 60 min passed between the end of irradiation and the initiation of column experiments, and high back pressures were observed for two out of the three experiments. This also made it difficult to determine what variable caused low Mo recovery. Radiation dose and starting iodine species had no effect on overall iodine speciation, and iodide was the predominant species for all tests.

  3. Grain boundary segregation and intergranular failure

    International Nuclear Information System (INIS)

    White, C.L.

    1980-01-01

    Trace elements and impurities often segregate strongly to grain boundaries in metals and alloys. Concentrations of these elements at grain boundaries are often 10 3 to 10 5 times as great as their overall concentration in the alloy. Because of such segregation, certain trace elements can exert a disproportionate influence on material properties. One frequently observed consequence of trace element segregation to grain boundaries is the occurrence of grain boundary failure and low ductility. Less well known are incidences of improved ductility and inhibition of grain boundary fracture resulting from trace element segregation to grain boundaries in certain systems. An overview of trace element segregation and intergranular failure in a variety of alloy systems as well as preliminary results from studies on Al 3% Li will be presented

  4. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Science.gov (United States)

    2010-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice...

  5. Ferroelectric domain continuity over grain boundaries

    DEFF Research Database (Denmark)

    Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

    2017-01-01

    Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... techniques in manipulating the micro-structure and domain structure to result in desired interactions between neighbouring grains could prove to be beneficial for future polycrystalline ferroelectric materials....

  6. Ventilation system for 99Mo production apparatus

    International Nuclear Information System (INIS)

    Izumo, Mishiroku; Okane, Shougo; Sorita, Takami; Aoyama, Saburou

    1978-04-01

    In production of 20 Ci 99 Mo from 235 U fission, about 120 Ci of radioiodine ( 131 I, 132 I, and 133 I) is involved. To remove airborne radioiodine from the exhaust air from production apparatus and minimize radioiodine release to the atmosphere, the ventilation system is equipped with 2 units of Model-FD charcoal filter (KI 3 -Impregnated charcoal 2 inch thick of Barnebey-Cheney Co.). From September 1976 to December 1977, 21 runs of 99 Mo production involving airborne radioiodine were carried out. The ventilation system was operated continuously for the whole 15 months period; variation in removal efficiency of airborne radioiodine from the exhaust air stream was observed. In the runs valuable experiences were gained in operation and maintenance of the ventilation system including activated charcoal filter and health-physics management of such facility. Following are the results: (1) Airborne radioiodine from 99 Mo production apparatus is reduced to 10 -3 % of the original quantity. (2) When the ventilation system is operated at a maximum air flow rate through the filter, the average efficiency during 15 months is over 98%. (3) Airborne radioiodine released from 99 Mo production apparatus to the ventilation system is less than 5% particulate iodine and alkyl iodines and more than 95% inorganic iodine. (4) Airborne radioiodine released from the stack is less than 28 μCi/run, which is below the limit in regulations on Radioisotope Production Laboratory. (auth.)

  7. Interface roughness in Mo/Si multilayers

    International Nuclear Information System (INIS)

    Nedelcu, I.; Kruijs, R.W.E. van de; Yakshin, A.E.; Tichelaar, F.; Zoethout, E.; Louis, E.; Enkisch, H.; Muellender, S.; Bijkerk, F.

    2006-01-01

    In this work we present a study of surface roughness development at the molybdenum-on-silicon and silicon-on-molybdenum interfaces in Mo/Si multilayers as employed in Extreme UV lithography. Thin Mo/Si multilayers, with layer thicknesses of 3-5 nm, were deposited using electron beam evaporation. The effect of ion treatment on the surface roughness was studied by X-ray reflectometry and transmission electron microscopy. Without ion treatment we observed build up of correlated roughness. The roughness development is shown here to depend strongly on the thickness of the crystalline Mo layer. Independent of the Mo ratio in a period, we show that a minimal amount of ion treatment is required to smoothen the multilayer roughness, which is also confirmed by EUV reflectivity measurements. At high ion energies the layers become smoother due to a larger ion penetration depth. The higher penetration depth is also shown to initiate additional interdiffusion and structural changes at buried interfaces

  8. Teens join the MoEDAL collaboration

    CERN Multimedia

    Stephanie Hills

    2013-01-01

    The principal investigator for any institute joining an experimental collaboration is generally a self-assured researcher with evident leadership skills and an in-depth knowledge of their subject gained over many years. Katherine Evans fits the brief in every respect, except that she is 17 years old and her research institute is the Langton Star Centre, based at the Simon Langton Grammar School for Boys. The school has just joined the MoEDAL experiment.   Teacher Becky Parker (left) with two students from the Simon Langton Grammar School for Boys in the MoEDAL experimental area. MoEDAL, the latest LHC experiment has detectors located close to the interaction point of the LHCb experiment. This new experiment is designed to search for the highly ionizing avatars of new physics at the LHC, specifically the magnetic monopole or dyon and other highly ionizing stable massive particles from a number of beyond-the-Standard-Model scenarios. MoEDAL was approved in 2010 and is due to start taking data i...

  9. Nanostructured Mo-B-C coatings

    Czech Academy of Sciences Publication Activity Database

    Buršík, Jiří; Buršíková, V.; Souček, P.; Zábranský, L.; Vašina, P.

    2016-01-01

    Roč. 68, č. 3 (2016), s. 1069-1075 ISSN 1841-8759 R&D Projects: GA ČR(CZ) GA15-17875S Institutional support: RVO:68081723 Keywords : magnetron sputtering * Mo-B-C coating * microstructure Subject RIV: JI - Composite Materials

  10. Mo-99 from low-enriched uranium

    International Nuclear Information System (INIS)

    Cols, Hector J.; Cristini, Pablo R.; Manzini, Alberto C.

    2000-01-01

    The use of low-enriched uranium aluminide targets for the production of fission Mo-99 is presented. Former tests on uranium silicide targets are also reviewed. Tests of dissolution of aluminide miniplates in alkaline medium were performed, showing interesting results for the replacement of current HEU targets. (author)

  11. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy.

    Science.gov (United States)

    Yang, Chao; Muránsky, Ondrej; Zhu, Hanliang; Thorogood, Gordon J; Avdeev, Maxim; Huang, Hefei; Zhou, Xingtai

    2017-04-06

    A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS) NiMo-based alloys containing varying amounts of SiC (0.5-2.5 wt %) were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA) route followed by spark plasma sintering (SPS) and rapid cooling. Neutron Powder Diffraction (NPD), Electron Back Scattering Diffraction (EBSD), and Transmission Electron Microscopy (TEM) were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni₃Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo₂C particles during sintering. The amount of grain boundaries greatly increases the Hall-Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

  12. Nanocomposite Nd-Y-Fe-B-Mo bulk magnets prepared by injection casting technique

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Shan [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China); Ahmad, Zubair [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, Pengyue [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China); Yan, Mi, E-mail: mse_yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zheng, Xiaomei [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China)

    2017-09-01

    Highlights: • Nanocomposite Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} sheet magnets were synthesized by injection casting. • High coercivity of 1289 kA/m was obtained for the directly casted magnet. • Magnetic properties arise from magnetically exchange coupled soft and hard phases. - Abstract: The phase composition, magnetic and microstructural properties of Nd{sub 2}Fe{sub 14}B/(α-Fe, Fe{sub 3}B) nanocomposite magnets produced by injection casting technique have been studied. Magnetic hysteresis loop of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} permanent magnet demonstrates the coercivity as high as 1289 kA/m. Electron microscopy elucidates a microstructure composed of magnetically soft α-Fe, Fe{sub 3}B and hard Nd{sub 2}Fe{sub 14}B/Y{sub 2}Fe{sub 14}B nanograins (20–50 nm) separated by ultra-thin grain boundary layer. The Henkel plot curve of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} magnet yields the existence of exchange coupling interactions between soft and hard phases. Macroscopically large size sheet magnet is obtained due to high glass forming ability of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} alloy derived from large atomic radius mismatch and negative enthalpy of alloy constituent elements. The high coercivity of the magnet is attributed to the magnetically hard phase increment, nucleation of reverse domains and the presence of thin grain boundary phase. Good magnetic properties such as remanence of 0.51 T, coercivity of 1289 kA/m and maximum energy product of 46.2 kJ/m{sup 3} are obtained in directly casted Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} sheet magnets.

  13. Development of large grain cavities

    Directory of Open Access Journals (Sweden)

    W. Singer

    2013-01-01

    Full Text Available DESY activities on 1.3 GHz tesla shape single cell and nine-cell large grain (LG resonators are presented; results of the past five years are covered. The R&D program explores the potential for production of elliptical superconducting cavities. The main efforts have been devoted to material investigation, development of LG disk production, cavity fabrication from this material, and a search for appropriate treatment. More than 250 LG disks are manufactured; several single cell and 11 nine-cell resonators are produced and rf tested after buffered chemical polishing and after additional electropolishing. A maximum accelerating gradient of approximately 45  MV/m for this type of cavity was achieved in two resonators. Two of the LG cavities have been installed and are currently being used in the FLASH accelerator operation. Assembly of a cryomodule, consisting of LG cavities only, is in the works. Perspectives of the LG cavity application are discussed.

  14. Grain orientation studies in superconductors

    Science.gov (United States)

    Gopalakrishnan, Sudhakar; Schulze, Walter A.

    1990-01-01

    Grain oriented fabrication of ceramics utilizes the presence of some form of anisotropy in the particles of the starting material to obtain textured microstructures. The molten salt, or flux method, a popular technique for growing crystals and particles with anisotropic morphology, is utilized in this study. The formation of Ba2YCu3O(7-x) in the presence of molten salts of Na, K, Li belonging to chloride and sulfate systems does not appear feasible in the temperature range up to 900 C. Researchers also present the results of studies in using BaY2CuO5 as seed crystals in the formation of Ba2YCu3O(7-x) wherein BaY2CuO5 has been observed to have better stability in water and against most of the salts as compared to Ba2YCu3O(7-x). Additional results of molten salt processing of bismuth systems are also presented.

  15. Signature spectrale des grains interstellaires.

    Science.gov (United States)

    Léger, A.

    Notre connaissance de la nature des grains interstellaires reposait sur un nombre très restreint de signatures spectrales dans la courbe d'extinction du milieu interstellaire. Une information considérable est contenue dans les 40 bandes interstellaires diffuses dans le visible, mais reste inexploitée. L'interprétation récente des cinq bandes IR en émission, en terme de molécules d'hydrocarbures aromatiques polycycliques, est développée. Elle permet l'utilisation d'une information spectroscopique comparable, à elle seule, à ce sur quoi était basée jusqu'alors notre connaissance de la matière interstellaire condensée. Différentes implications de cette mise en évidence sont proposées.

  16. The effects of irradiation on grain coat color and grain texture in winter wheat

    International Nuclear Information System (INIS)

    Miao Bingliang; Liu Xueyu

    1989-01-01

    Dry seeds of the variety ''Yangmai 5'' with red grain coat, semihard grain texture, and the variety ''Ningmai 3'' with red grain coat, soft grain texture were irradiated with Y-rays at various doses.The effect on M1 grain coat color was different between two varieties, the higher doses made grain coat color of ''Yangmai 5'' redder, but had hardly effect on ''Ningmai 3''.The effect on M1 grain texture showed that the grain texture became softer with doses increased.It was found that there were 0.6% of positive ( red to white ) grain coat color mutants and 2.0% of negative(hard to soft) grain texture mutants in M2 of ''Yangmai 5'', and there were 0.7% of negative ( white to red ) grain coat color mutants and 3.6% of positive ( soft to hard ) grain texture mutants in M2 of ''Ningmai 3''. It seemed that the positive mutants selected in M3 were stable in M4. The results showed that γ-rays can be used to improve the grain coat color andgrain texture of wheat varieties

  17. Grain interaction effects in polycrystalline Cu

    DEFF Research Database (Denmark)

    Thorning, C.; Somers, Marcel A.J.; Wert, John A.

    2005-01-01

    Crystal orientation maps for a grain in a deformed Cu polycrystal have been analysed with the goal of understanding the effect of grain interactions on orientation subdivision. The polycrystal was incrementally strained in tension to 5, 8, 15 and 25% extension; a crystal orientation map was measu......Crystal orientation maps for a grain in a deformed Cu polycrystal have been analysed with the goal of understanding the effect of grain interactions on orientation subdivision. The polycrystal was incrementally strained in tension to 5, 8, 15 and 25% extension; a crystal orientation map...

  18. Analysis of MoDOT communication and outreach effectiveness

    Science.gov (United States)

    2008-07-01

    Personal interviews were held with MoDOT personnel to assess MoDOTs current communication practices and existing customer segmentation practices. Focus groups were then held to help gauge the effectiveness of existing communication practices and t...

  19. X-ray fluorescence analysis of Fe - Ni - Mo systems

    International Nuclear Information System (INIS)

    Belyaev, E.E.; Ershov, A.V.; Mashin, A.I.; Mashin, N.I.; Rudnevskij, N.K.

    1998-01-01

    Procedures for the X-ray fluorescence determination of the composition and thickness of Fe - Ni - Mo thin films and the concentration of elements in thick films of the Fe - Ni - Mo alloy are developed [ru

  20. MoO x /Ag/MoO x transparent electrode by solution process

    Science.gov (United States)

    Kan, Ryota; Yamano, Yuka; Tani, Tadaaki; Uchida, Takayuki

    2017-05-01

    We have investigated a dielectric-metal-dielectric (DMD) multilayer film, which is unique as compared with such conventional transparent conductive oxides as indium tin oxide (ITO). In this study, we have selected MoO3 and Ag as the dielectric material and metal, respectively, and employed a nano-mist method in addition to a vacuum evaporation one. The transmission spectra of the films indicated that the Ag morphology changed from isolated islands to continuous layers with increasing Ag layer thickness, and that the morphology change was enhanced by MoO3. Then, MoO3/Ag/MoO3 (MAM) multilayer-structured transparent electrodes could be fabricated by a nano-mist method as well as by a vacuum evaporation one. Comparative examination is made on the properties of MAM films fabricated by these two methods for their application.

  1. The Service Life of the Repair Welded Joint of Cr-Mo / Cr-Mo-V

    Directory of Open Access Journals (Sweden)

    Sroka M.

    2016-09-01

    Full Text Available This paper presents the evaluation of the service life of dissimilar repair welded joint from Cr-Mo/Cr-Mo-V steel after 200,000 h service under creep condition. The investigations of microstructure using scanning electron microscopy, investigations of mechanical properties at room and elevated temperature as well as creep tests of the basic material from Cr-Mo and Cr-Mo-V steel and welded joint from these steels were carried out. The investigations allowed the time of further safe operation of the repair welded joint in relation to the residual life of the materials to be determined. The evaluation of residual life and disposable residual life, and thus the estimation or determination of possible time of further safe operation, is crucial when the elements are operated much beyond the design work time.

  2. Interdiffusion between U(Mo,Pt) or U(Mo,Zr) and Al or Al A356 alloy

    International Nuclear Information System (INIS)

    Komar Varela, C.; Mirandou, M.; Arico, S.; Balart, S.; Gribaudo, L.

    2009-01-01

    Solid state reactions in chemical diffusion couples U-7 wt.%Mo-0.9 wt.%Pt/Al at 580 deg. C and U-7 wt.%Mo-0.9 wt.%Pt/Al A356 alloy, U-7 wt.%Mo-1 wt.%Zr/Al and U-7 wt.%Mo-1 wt.%Zr/Al A356 alloy at 550 deg. C were characterized. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The UAl 3, UAl 4 and Al 20 Mo 2 U phases were identified in the interaction layers of γU(Mo,Pt)/Al and γU(Mo,Zr)/Al diffusion couples. Al 43 Mo 4 U 6 ternary compound was also identified in γU(Mo,Zr)/Al due to the decomposition of γU(Mo,Zr) phase. The U(Al,Si) 3 and U 3 Si 5 phases were identified in the interaction layers of γU(Mo,Pt)/Al A356 and γU(Mo,Zr)/Al A356 diffusion couples. These phases are formed due to the migration of Si to the interaction layer. In the diffusion couple U(Mo,Zr)/Al A356, Zr 5 Al 3 phase was also identified in the interaction layer. The use of synchrotron radiation at Brazilian Synchrotron Light Laboratory (LNLS, CNPq, Campinas, Brazil) was necessary to achieve a complete crystallographic characterization.

  3. Grain-boundary engineering applied to grain growth in a high temperature material

    International Nuclear Information System (INIS)

    Huda, Z.

    1993-01-01

    Crystallography of grain boundaries are determined for a high temperature material, before and after grain growth processes, so as to study the induction of special properties useful for application in components of a gas-turbine engine. The philosophy of grain-boundary engineering is applied to grain growth in APK-6, a powder formed nickel-base superalloy so as to establish the possible structure/property relationships. The alloy in the as received condition is shown to possess a strong texture and contained coincident site lattices (CSL) boundaries with most boundaries having sigma values in the range of 3 > sigma > 25. A normal grain-growth heat treatment result in a good population of low angle grain boundaries, and drastically reduces the proportion of CSL boundaries. A strong [011] annealing texture is observed after an intermediate grain growth; most grain boundaries, here, tend to be high angle indicating a possibility of possessing special properties. (author)

  4. Supercube grains leading to a strong cube texture and a broad grain size distribution after recrystallization

    DEFF Research Database (Denmark)

    Lin, F.X.; Zhang, Y. B.; Pantleon, W.

    2015-01-01

    growth rates. However, most other cube grains do not grow preferentially. Because of the few supercube grains, the grain size distribution after recrystallization is broad. Reasons for the higher growth rates of supercube grains are discussed, and are related to the local deformed microstructure.......This work revisits the classical subject of recrystallization of cold-rolled copper. Two characterization techniques are combined: three-dimensional X-ray diffraction using synchrotron X-rays, which is used to measure the growth kinetics of individual grains in situ, and electron backscatter...... diffraction, which is used for statistical analysis of the microstructural evolution. As the most striking result, the strong cube texture after recrystallization is found to be related to a few super large cube grains, which were named supercube grains. These few supercube grains become large due to higher...

  5. Evolution of orientations and deformation structures within individual grains in cold rolled columnar grained nickel

    International Nuclear Information System (INIS)

    Wu, G.L.; Godfrey, A.; Winther, G.; Juul Jensen, D.; Liu, Q.

    2011-01-01

    Columnar grained Ni is used as a model material allowing simultaneous non-surface investigations of the evolution of crystallographic orientations and deformation microstructures within individual grains as a function of rolling strain up to ε = 0.7. Electron channelling contrast and electron backscattered diffraction are used to visualise microstructures and crystallographic orientations. It is found that both the microstructural and the textural development depend strongly on the initial grain orientation. A grain size effect is observed on the deformation-induced orientation scatter within the grains. Large grains have microstructure and orientation scatters similar to those observed in single crystals of similar orientation. The observations are interpreted based on a slip system analysis, considering the relative effects of the initial grain orientation and the interaction between neighbouring grains as well.

  6. Abnormal grain growth: a non-equilibrium thermodynamic model for multi-grain binary systems

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Fischer, F. D.

    2014-01-01

    Roč. 22, č. 1 (2014), Art. No. 015013 ISSN 0965-0393 Institutional support: RVO:68081723 Keywords : grain boundary segregation * abnormal grain growth * theory * modelling * solute drag Subject RIV: BJ - Thermodynamics Impact factor: 2.167, year: 2014

  7. The Role of Grain Boundary Energy on Grain Boundary Complexion Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Bojarski, Stephanie A. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering; Rohrer, Gregory S. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering

    2014-09-01

    Grain boundary complexions are distinct equilibrium structures and compositions of a grain boundary and complexion transformations are transition from a metastable to an equilibrium complexion at a specific thermodynamic and geometric conditions. Previous work indicates that, in the case of doped alumina, a complexion transition that increased the mobility of transformed boundaries and resulted in abnormal grain growth also caused a decrease in the mean relative grain boundary energy as well as an increase in the anisotropy of the grain boundary character distribution (GBCD). The current work will investigate the hypothesis that the rates of complexion transitions that result in abnormal grain growth (AGG) depend on grain boundary character and energy. Furthermore, the current work expands upon this understanding and tests the hypothesis that it is possible to control when and where a complexion transition occurs by controlling the local grain boundary energy distribution.

  8. Grain Unloading of Arsenic Species in Rice

    Energy Technology Data Exchange (ETDEWEB)

    Carey, Anne-Marie; Scheckel, Kirk G.; Lombi, Enzo; Newville, Matt; Choi, Yongseong; Norton, Gareth J.; Charnock, John M.; Feldmann, Joerg; Price, Adam H.; Meharg, Andrew A. (EPA); (U. South Australia); (Manchester); (Aberdeen); (UC)

    2010-01-11

    Rice (Oryza sativa) is the staple food for over half the world's population yet may represent a significant dietary source of inorganic arsenic (As), a nonthreshold, class 1 human carcinogen. Rice grain As is dominated by the inorganic species, and the organic species dimethylarsinic acid (DMA). To investigate how As species are unloaded into grain rice, panicles were excised during grain filling and hydroponically pulsed with arsenite, arsenate, glutathione-complexed As, or DMA. Total As concentrations in flag leaf, grain, and husk, were quantified by inductively coupled plasma mass spectroscopy and As speciation in the fresh grain was determined by x-ray absorption near-edge spectroscopy. The roles of phloem and xylem transport were investigated by applying a {+-} stem-girdling treatment to a second set of panicles, limiting phloem transport to the grain in panicles pulsed with arsenite or DMA. The results demonstrate that DMA is translocated to the rice grain with over an order magnitude greater efficiency than inorganic species and is more mobile than arsenite in both the phloem and the xylem. Phloem transport accounted for 90% of arsenite, and 55% of DMA, transport to the grain. Synchrotron x-ray fluorescence mapping and fluorescence microtomography revealed marked differences in the pattern of As unloading into the grain between DMA and arsenite-challenged grain. Arsenite was retained in the ovular vascular trace and DMA dispersed throughout the external grain parts and into the endosperm. This study also demonstrates that DMA speciation is altered in planta, potentially through complexation with thiols.

  9. Electron microscopy studies on MoS2 nanocrystals

    DEFF Research Database (Denmark)

    Hansen, Lars Pilsgaard

    Industrial-style MoS2-based hydrotreating catalysts are studied using electron microscopy. The MoS2 nanostructures are imaged with single-atom sensitivity to reveal the catalytically important edge structures. Furthermore, the in-situ formation of MoS2 crystals is imaged for the first time....

  10. 76 FR 31822 - Amendment of Class E Airspace; Mosby, MO

    Science.gov (United States)

    2011-06-02

    ... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Mosby, MO AGENCY: Federal... Mosby, MO. Decommissioning of the Mosby non-directional beacon (NDB) at Midwest National Air Center Airport, Mosby, MO, has made this action necessary to enhance the safety and management of Instrument...

  11. Auger Spectroscopy Analysis of Spalled LEU-10Mo Foils

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, Samantha Kay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schulze, Roland K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Presentation includes slides on Surface Science used to probe LEU-10Mo Spall; Auger highlights graphitic-like inclusions and Mo-deficient oxide on base metal; Higher C concentration detected within spall area Images Courtesy; Depth profiling reveals thick oxide; Mo concentration nears nominal only at depths ~400 nm; and lastly Key Findings.

  12. The effect of thermomechanical processing on second phase particle redistribution in U-10 wt%Mo

    Science.gov (United States)

    Hu, Xiaohua; Wang, Xiaowo; Joshi, Vineet V.; Lavender, Curt A.

    2018-03-01

    The multi-pass hot-rolling process of an annealed uranium-10 wt% molybdenum (U10Mo) coupon was studied by plane-strain compression finite element modeling. As-cast U10Mo typically contains second phase particles such as uranium carbides (UC) and silicides along the grain boundaries. The volume fraction of UC is typically large, while the other phases can be redissolved in the matrix by certain heat treatments. The UC particle distribution is important due to its influence on the recrystallization processes (particle stimulated nucleation) that occur during annealing between rolling passes. Unfavorable particle distribution and fracture after rolling can affect the grain size and also influence the fuel performance in the reactor. A statistical method, i.e., the two-point correlation function (2PCF), was used to analyze the carbide particle distribution after each rolling reduction. The hot rolling simulation results show that the alignment of UC particles along grain boundaries will rotate during rolling until it is parallel to the rolling direction, to form stringer-like distributions which are typically observed in rolled products that contain inclusions. 2PCF analysis shows that the interparticle spacing shrinks along the normal direction (ND) and increases along the rolling direction (RD). The simulated particle distribution is very similar to that measured experimentally for similar rolling reductions. The magnitudes of major peaks of 2PCF along the ND decrease after large reduction. The locations of major peaks indicate the inter-stringer distances. Many more small peaks appear for the 2PCF along the RD, and this is related to the neighboring particles within stringers, which are along the RD.

  13. Phase II Investigation at the Former CCC/USDA Grain Storage Facility in Savannah, Missouri

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, Lorraine M. [Argonne National Lab. (ANL), Argonne, IL (United States). Environmental Science Division. Applied Geosciences and Environmental Management Section

    2012-05-01

    From approximately 1949 until 1970, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility on federally owned property approximately 0.25 mi northwest of Savannah, Missouri. During this time, commercial grain fumigants containing carbon tetrachloride were commonly used by the CCC/USDA and the private grain storage industry to preserve grain in their facilities. In November 1998, carbon tetrachloride was detected in a private well (Morgan) roughly 50 ft south of the former CCC/USDA facility, as a result of statewide screening of private wells near former CCC/USDA facilities, conducted in Missouri by the U.S. Environmental Protection Agency (EPA 1999). The 1998 and subsequent investigations by the EPA and the Missouri Department of Natural Resources (MDNR) confirmed the presence of carbon tetrachloride in the Morgan well, as well as in a second well on property currently owned by the Missouri Department of Transportation (MoDOT), directly east of the former CCC/USDA facility. The identified concentrations in these two wells were above the EPA maximum contaminant level (MCL) and the Missouri risk-based corrective action default target level (DTL) values of 5.0 μg/L for carbon tetrachloride in water used for domestic purposes (EPA 1999; MDNR 2000a,b, 2006). Because the observed contamination in the Morgan and MoDOT wells might be linked to the past use of carbon tetrachloride-based fumigants at its former grain storage facility, the CCC/USDA is conducting an investigation to (1) characterize the source(s), extent, and factors controlling the subsurface distribution and movement of carbon tetrachloride and (2) evaluate the potential risks to human health, public welfare, and the environment posed by the contamination. This work is being performed in accord with an Intergovernmental Agreement established in 2007 between the Farm Service Agency of the USDA and the MDNR, to address carbon tetrachloride

  14. Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

    Science.gov (United States)

    McCallum, R.W.; Branagan, D.J.

    1996-01-23

    A method of making a permanent magnet is disclosed wherein (1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and (2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties. 33 figs.

  15. Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel

    Science.gov (United States)

    Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

    2012-01-01

    A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength–toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation. PMID:27877493

  16. Effect of La doping on the electrochemical activity of double perovskite oxide Sr2FeMoO6 in alkaline medium

    International Nuclear Information System (INIS)

    Azizi, F.; Kahoul, A.; Azizi, A.

    2009-01-01

    The crystalline structure, grain morphology, electrical and electrochemical properties of Sr 2-x La x FeMoO 6 (x = 0, 0.25, 0.5 and 1) double perovskite has been investigated by means of X-ray powder diffraction, scanning electron micrography, electrical and electrochemical measurements. It was found that the grain morphology, the resistivity and the electrochemical activity are strongly influenced by La doping. While the surface area as the determining factor in the oxygen reaction rate was excluded, the electrical resistivity was found to have a great effect on the electrochemical activity of the compounds.

  17. GRAIN QUALITY IN SIERRA LEONE I

    African Journals Online (AJOL)

    Mimi

    and traders, as well as the marketing practices and aspirations for the improvement of rice grain quality in the ... smallholders who use manual traditional processing and handling practices like head portage for ... The study was a national market perception survey on the nature of rice grain quality in Sierra Leone with ...

  18. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    Unknown

    Spinodal decomposition in fine grained materials. H RAMANARAYAN and T A ABINANDANAN*. Department of Metallurgy, Indian Institute of Science, Bangalore 560 012, India. Abstract. We have used a phase field model to study spinodal decomposition in polycrystalline materials in which the grain size is of the same ...

  19. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    We have used a phase field model to study spinodal decomposition in polycrystalline materials in which the grain size is of the same order of magnitude as the characteristic decomposition wavelength ( λ S D ). In the spirit of phase field models, each grain () in our model has an order parameter ( η i ) associated with it; ...

  20. Evidence from Ethiopian Grain Traders and Millers

    African Journals Online (AJOL)

    Daniel

    According to Dessalegn et.al. (1997), limited access to finance was identified as one of the major constraints of grain marketing in Ethiopia. Traders who did not obtain loan from banks identified lack of collateral, high risk in grain trade and high competition from unlicensed traders as the main reasons constraining access to ...

  1. Insect Population Dynamics in Commercial Grain Elevators

    Science.gov (United States)

    Data were collected in 1998-2002 from wheat stored in commercial grain elevators in south-central Kansas. Storage bins at these elevators had concrete walls and were typically 6-9 m in diameter and 30-35 m tall. A vacuum-probe sampler was used to collect ten 3-kg grain samples in the top 12 m of the...

  2. Grain refinement of zinc-aluminium alloys

    International Nuclear Information System (INIS)

    Zaid, A.I.O.

    2006-01-01

    It is now well-established that the structure of the zinc-aluminum die casting alloys can be modified by the binary Al-Ti or the ternary Al-Ti-B master alloys. in this paper, grain refinement of zinc-aluminum alloys by rare earth materials is reviewed and discussed. The importance of grain refining of these alloys and parameters affecting it are presented and discussed. These include parameters related to the Zn-Al alloys cast, parameters related to the grain refining elements or alloys and parameters related to the process. The effect of addition of other alloying elements e.g. Zr either alone or in the presence of the main grain refiners Ti or Ti + B on the grain refining efficiency is also reviewed and discussed. Furthermore, based on the grain refinement and the parameters affecting it, a criterion for selection of the optimum grain refiner is suggested. Finally, the recent research work on the effect of grain refiners on the mechanical behaviour, impact strength, wear resistance, and fatigue life of these alloys are presented and discussed. (author)

  3. A new treatment of transient grain growth

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Fratzl, P.; Zickler, G. A.; Fischer, F. D.

    2016-01-01

    Roč. 115, AUG (2016), s. 442-447 ISSN 1359-6454 R&D Projects: GA ČR(CZ) GA15-06390S Institutional support: RVO:68081723 Keywords : Grain size distribution * Grain growth * Growth kinetics * Thermodynamic modelling * Numerical solution of integro-differential equations Subject RIV: BJ - Thermodynamic s Impact factor: 5.301, year: 2016

  4. Grain transport mechanics in shallow flow

    Science.gov (United States)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flows. The two-phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a dispe...

  5. Grain transport mechanics in shallow overland flow

    Science.gov (United States)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flow. The two phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a disper...

  6. Study on the solid solubility extension of Mo in Cu by mechanical alloying Cu with amorphous Cr(Mo)

    International Nuclear Information System (INIS)

    Xi Shengqi; Zuo Kesheng; Li Xiaogang; Ran Guang; Zhou Jingen

    2008-01-01

    This paper presents the extension of the solid solubility of Mo in Cu by a mechanical alloying technique. Two binary systems, Cu-10 wt.% Mo and Cr-50 wt.% Mo, and one ternary system, Cu-20 wt.% Cr(Mo), are investigated. The solid solubility of Mo in Cu has been shown to be less than 4.3 at.% when the Cu-Mo system is mechanically alloyed, whereas when the Cr-Mo system is mechanically alloyed all of Mo dissolves into Cr, forming an amorphous Cr(Mo). Similarly, all of 10 wt.% Mo dissolve into Cu when Cu-20 wt.% amorphous Cr(Mo) is mechanically alloyed. Based on Miedema's model, the Gibbs free-energy changes in these three alloy systems during the formation of solid solutions are calculated to be positive, which means that thermodynamic barriers exist for the formation of these three alloy systems in solid solution states. The mechanism of solid solubility extension in these mechanical alloyed systems is discussed. The conclusion is that the extension of solid solubility is favoured by adding a third element, such as Cr, to the Cu-Mo system

  7. Edge-Riched MoSe2 /MoO2 Hybrid Electrocatalyst for Efficient Hydrogen Evolution Reaction.

    Science.gov (United States)

    Jian, Chuanyong; Cai, Qian; Hong, Wenting; Li, Jing; Liu, Wei

    2018-03-01

    Molybdenum diselenide (MoSe 2 ) is widely considered as one of the most promising catalysts for the hydrogen evolution reaction (HER). However, the absence of active sites and poor conductivity of MoSe 2 severely restrict its HER performance. By introducing a layer of MoO 2 on Mo foil, MoSe 2 /MoO 2 hybrid nanosheets with an abundant edge and high electrical conductivity can be synthesized on the surface of Mo foil. Metallic MoO 2 can improve the charge transport efficiency of MoSe 2 /MoO 2 , thereby enhancing the overall HER performance. MoSe 2 /MoO 2 exhibits fast hydrogen evolution kinetics with a small overpotential of 142 mV versus RHE at a current density of 10 mA cm -2 and Tafel slope of 48.9 mV dec -1 . © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. High pressure effect on MoS2 and MoSe2 single crystals grown by ...

    Indian Academy of Sciences (India)

    Unknown

    tetrahedral anvil apparatus up to 5 GPa. In this paper we report room temperature resistance mea- surements as a function of pressure on MoS2 and MoSe2 single crystals. In each case the resistance decreases un- der pressure due to an increase in the carrier concentration. 2. Experimental. Single crystals of MoS2 and ...

  9. The Rosseland mean opacity of interstellar grain

    International Nuclear Information System (INIS)

    Ali, A.; El Shalaby, M.A.; El-Nawawy, M.S.

    1990-10-01

    We have calculated the opacity of interstellar grains in the temperature range 10 deg. K - 1500 deg. K. Two composite grain models have been considered. One of them consists of silicate coated with ice mantle and the second has a graphite core coated also with ice mantle. These models are compared with isolated grain models. An exact analytical and computational development of Guettler's formulae for composite grain models has been used to calculate the extinction coefficient. It has been found that the thickness of the mantle affects the opacity of the interstellar grains. The opacity of composite models differs from that of the isolated models. The effect of the different species (ice, silicate and graphite) is also clear. (author). 22 refs, 4 figs, 1 tab

  10. Grain Boundary Engineering of Electrodeposited Thin Films

    DEFF Research Database (Denmark)

    Alimadadi, Hossein

    Grain boundary engineering aims for a deliberate manipulation of the grain boundary characteristics to improve the properties of polycrystalline materials. Despite the emergence of some successful industrial applications, the mechanism(s) by which the boundary specific properties can be improved...... to engineer new materials. In this study, one of the most widely used electrolytes for electrodeposition is chosen for the synthesis of nickel films and based on thorough characterization of the boundaries the potentials in grain boundary engineering are outlined. The internal structure of the nickel films...... of the favorable boundaries that break the network of general grain boundaries. Successful dedicated synthesis of a textured nickel film fulfilling the requirements of grain boundary engineered materials, suggests improved boundary specific properties. However, the textured nickel film shows fairly low...

  11. Plant Density Effect on Grain Number and Weight of Two Winter Wheat Cultivars at Different Spikelet and Grain Positions

    Science.gov (United States)

    Ni, Yingli; Zheng, Mengjing; Yang, Dongqing; Jin, Min; Chen, Jin; Wang, Zhenlin; Yin, Yanping

    2016-01-01

    In winter wheat, grain development is asynchronous. The grain number and grain weight vary significantly at different spikelet and grain positions among wheat cultivars grown at different plant densities. In this study, two winter wheat (Triticum aestivum L.) cultivars, ‘Wennong6’ and ‘Jimai20’, were grown under four different plant densities for two seasons, in order to study the effect of plant density on the grain number and grain weight at different spikelet and grain positions. The results showed that the effects of spikelet and grain positions on grain weight varied with the grain number of spikelets. In both cultivars, the single-grain weight of the basal and middle two-grain spikelets was higher at the 2nd grain position than that at the 1st grain position, while the opposite occurred in the top two-grain spikelets. In the three-grain spikelets, the distribution of the single-grain weight was different between cultivars. In the four-grain spikelets of Wennong6, the single-grain weight was the highest at the 2nd grain position, followed by the 1st, 3rd, and 4th grain positions. Regardless of the spikelet and grain positions, the single-grain weight was the highest at the 1st and 2nd grain positions and the lowest at the 3rd and 4th grain positions. Overall, plant density affected the yield by controlling the seed-setting characteristics of the tiller spike. Therefore, wheat yield can be increased by decreasing the sterile basal and top spikelets and enhancing the grain weight at the 3rd and 4th grain positions, while maintaining it at the 1st and 2nd grain positions on the spikelet. PMID:27171343

  12. β-Nd2Mo4O15

    Directory of Open Access Journals (Sweden)

    Chang-An Huan

    2010-12-01

    Full Text Available The title compound, dineodymium(III tetramolybdate(VI, has been prepared by a flux technique and is the second polymorph of composition Nd2Mo4O15. The crystal structure is isotypic with those of Ce2Mo4O15 and Pr2Mo4O15. It features a three-dimensional network composed of distorted edge- and corner-sharing NdO7 polyhedra, NdO8 polyhedra, MoO4 tetrahedra and MoO6 octahedra.

  13. Manufacture for prototype Mo-99 irradiation target

    Energy Technology Data Exchange (ETDEWEB)

    Son, Myung Koon; Kim, Ki Hwan; Lee, Byung Chul; Park, Jong Hyuk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2005-07-01

    The prototype of target to produce Mo-99 by fission has been manufactured. Extension equipment using oil pressure is specially designed and fabricated in order to prepare the Mo-99 target of high quality to be irradiated in a research reactor. The target of an annular type of inner and outer Al tubes and uranium foil in between is extended using a dedicated tool with a draw plug. The inner tube is plastically deformed while the outer tube is elastically deformed. This makes the Al tubes and foil contacted closely. Top and bottom ends of the target are welded by TIG in order to provide a hermetic sealing which will prevent the release of fission gases during the irradiation.

  14. Mo(ve)ments Beyond Marginalization

    DEFF Research Database (Denmark)

    Mørck, Line Lerche

    2018-01-01

    , hvordan teorien om grænsefællesskaber er blevet anvendt og videreudviklet over tid i arbejdet med overskridelse af marginalisering i og på tværs af forskellige forskningsprojekter. Artiklen illustrerer bl.a. hvordan ’mo(ve)ments beyond marginalisation’ udforskes og samskabes i forskningssamarbejdet, bl.......a. med en tidligere rocker, der er i gang med sin exitproces. Et samarbejde der bl.a. resulterede i udviklingen af en særlig metode til at udforske identitetstransformation, den såkaldte mo(ve)ment-metodologi og i nye strategier for social praksis etik. Artiklen ender med at præsentere en metode til...

  15. Research on low strain magnetic mechanical hysteresis damping performance of Fe-15Cr-3Mo-0.5Si alloy

    International Nuclear Information System (INIS)

    Wang, Hui; Huang, Huawei; Hong, Xiaofeng; Yin, Changgeng; Huang, Zhaohua; Chen, Le

    2015-01-01

    Highlights: • Heat treatment system has a great effect on the alloy damping performance. • Damping performance does not improve monotonously with temperature. • Furnace cooling is higher than that of alloy after air cooling. • There is an optimum annealing temperature and grain size to obtain high damping. - Abstract: This paper studies the preparation of Fe-15Cr-3Mo-0.5Si alloy by using vacuum induction melting furnace and vacuum annealing furnace, the damping performance of which in different heat treatment states is tested with dynamic mechanical thermal analyzer (DMA). Through microstructure observation with metallographic microscope (OM), grain boundary observation with scanning electron microscopy (SEM), phase structure analysis with X-ray diffraction (XRD) and internal stress of S-B model analysis, the effect law of annealing temperature, types of cooling, holding time and grain sizes on the damping performance of alloy and the related mechanism can be concluded as follows. The annealing temperature and grain sizes have a significant impact on the damping strain amplitude as well as the magnetic and mechanical damping performance of this ferromagnetic alloy. Proper annealing temperature and grain size is the necessary condition to get high damping performance of the alloy. It is not conducive to improvement of the damping performance if the annealing temperature is too high or too low and the grain size is too small or too large. For Fe-15Cr-3Mo-0.5Si alloy, within the range of the low strain amplitude, alloy damping performance does not improve monotonously with the increase of the annealing temperature and grain size. The maximum value appears at the annealing temperature of 1100 °C/1 h with the grain size of about 300 μm. At high annealing temperature of 1100 °C, the damping performance of alloy in the slow cooling furnace is higher than that with air cooling treatment. The extension or shortening of the holding time, to a certain extent

  16. Effect of Ultrasonic Melt Treatment on Microstructure and Mechanical Properties of 35CrMo Steel Casting

    Science.gov (United States)

    Shi, Chen; Li, Fan; Liang, Gen; Mao, Daheng

    2018-01-01

    Effects of different power ultrasonic on microstructure and mechanical properties of 35CrMo steel casting were investigated using optical microscopy (OM), scanning electron microscopy (SEM) and hardness testing. A self-developed experiment apparatus was used for the propagation of ultrasonic vibration into the 35CrMo steel melt to carry out ultrasonic treatment. The experimental results showed that compared to the traditional casting, ultrasonic treatment can obviously change the solidification microstructure of 35CrMo steel, which is changed from coarse dendrites to fined dendrites or equiaxed grains. With the increase of ultrasonic power, equiaxed crystal is remarkably refined and its area is broadened. The micro porosity percentage of ingot casting decreases significantly and the porosity defects can be suppressed under ultrasonic treatment. The mechanical properties of 35CrMo steel ingot after heat treatment were enhanced by ultrasonic treatment: the maximum tensile strength is improved by 8.4% and the maximum elongation increased by 1.5 times.

  17. Results of U-xMo (x=7, 10, 12 wt.%) Alloy versus Al-6061 Cladding Diffusion Couple Experiments Performed at 500, 550 and 600 Degrees C

    Energy Technology Data Exchange (ETDEWEB)

    Emmanuel Perez; Dennis D. Keiser, Jr.; Yongho Sohn

    2013-04-01

    The Reduced Enrichment for Research and Test Reactors (RERTR) program has been developing low enrichment fuel systems encased in Al 6061 for use in research and test reactors. U–Mo alloys in contact with Al and Al alloys can undergo diffusional interactions that can result in the development of interdiffusion zones with complex fine-grained microstructures composed of multiple phases. A monolithic fuel currently being developed by the RERTR program has local regions where the U–Mo fuel plate is in contact with the Al 6061 cladding and, as a result, the program finds information about interdiffusion zone development at high temperatures of interest. In this study, the microstructural development of diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo, and U-12wt.%Mo vs. Al 6061 (or 6061 aluminum) cladding, annealed at 500, 550, 600 degrees C for 1, 5, 20, 24, or 132 hours, was analyzed by backscatter electron microscopy and x-ray energy dispersive spectroscopy on a scanning electron microscope. Concentration profiles were determined by standardized wavelength dispersive spectroscopy and standardless x-ray energy dispersive spectroscopy. The results of this work shows that the presence of surface layers at the U–Mo/Al 6061 interface can dramatically impact the overall interdiffusion behavior in terms of rate of interaction and uniformity of the developed interdiffusion zones. It further reveals that relatively uniform interaction layers with higher Si concentrations can develop in U–Mo/Al 6061 couples annealed at shorter times and that longer times at temperature result in the development of more non-uniform interaction layers with more areas that are enriched in Al. At longer annealing times and relatively high temperatures, U–Mo/Al 6061 couples can exhibit more interaction compared to U–Mo/pure Al couples. The minor alloying constituents in Al 6061 cladding can result in the development of many complex phases in the interaction layer of U–Mo

  18. Short Communication. Effect of phosphorus nutrition and grain position within maize cob on grain phosphorus accumulation

    Directory of Open Access Journals (Sweden)

    Muhamamad Nadeem

    2014-04-01

    Full Text Available Nutritional status of grains may vary due to external nutrient supply and their position within parent maize cob. Phosphorus (P is the least mobile nutrient in the soil and therefore newly growing seedlings are largely dependent on the stored grain P contents which are accumulated during the crop maturity period. Objective of this study was to access the effects of different P applications and grain positions on P and dry matter contents in grains. Phosphorus application and grain position has significant (p<0.05 effects on P contents in grains whereas dry weight and P content are highly correlated. Grain weight and P contents decreased linearly from base to apical position possibly due to flow of nutrients from base towards apical position within cob. Significantly higher grain dry weight (0.35±0.01 g and P contents (962±57 µg P are recorded in high P application (92.50 kg ha-1 rate on base position whereas minimum grain dry weight (0.14±0.01 g and P contents (219±11 µg P were recorded on apical grain position in low P application (5.60 kg ha-1 rate. The results suggest that for better seedling P nutrition especially in soils of low inherent P, maize grains should be selected from base or middle position where maximum dry weight and P contents are concentrated to support the seedlings to reach at growth at which roots are capable of external P uptake.

  19. MoRFPred-plus: Computational Identification of MoRFs in Protein Sequences using Physicochemical Properties and HMM profiles.

    Science.gov (United States)

    Sharma, Ronesh; Bayarjargal, Maitsetseg; Tsunoda, Tatsuhiko; Patil, Ashwini; Sharma, Alok

    2018-01-21

    Intrinsically Disordered Proteins (IDPs) lack stable tertiary structure and they actively participate in performing various biological functions. These IDPs expose short binding regions called Molecular Recognition Features (MoRFs) that permit interaction with structured protein regions. Upon interaction they undergo a disorder-to-order transition as a result of which their functionality arises. Predicting these MoRFs in disordered protein sequences is a challenging task. In this study, we present MoRFpred-plus, an improved predictor over our previous proposed predictor to identify MoRFs in disordered protein sequences. Two separate independent propensity scores are computed via incorporating physicochemical properties and HMM profiles, these scores are combined to predict final MoRF propensity score for a given residue. The first score reflects the characteristics of a query residue to be part of MoRF region based on the composition and similarity of assumed MoRF and flank regions. The second score reflects the characteristics of a query residue to be part of MoRF region based on the properties of flanks associated around the given residue in the query protein sequence. The propensity scores are processed and common averaging is applied to generate the final prediction score of MoRFpred-plus. Performance of the proposed predictor is compared with available MoRF predictors, MoRFchibi, MoRFpred, and ANCHOR. Using previously collected training and test sets used to evaluate the mentioned predictors, the proposed predictor outperforms these predictors and generates lower false positive rate. In addition, MoRFpred-plus is a downloadable predictor, which makes it useful as it can be used as input to other computational tools. https://github.com/roneshsharma/MoRFpred-plus/wiki/MoRFpred-plus:-Download. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Theoretical calculations of valence states in Fe-Mo compounds

    International Nuclear Information System (INIS)

    Estrada, F; Navarro, O; Noverola, H; Suárez, J R; Avignon, M

    2014-01-01

    The half-metallic ferromagnetic double perovskite compound Sr 2 FeMoO 6 is considered as an important material for spintronic applications. It appears to be fundamental to understand the role of electronic parameters controlling the half-metallic ground state. Fe-Mo double perovskites usually present some degree of Fe/Mo disorder which generally increases with doping. In this work, we study the valence states of Fe-Mo cations in the off-stoichiometric system Sr 2 Fe 1+x Mo 1−x O 6 (−1 ≤ x ≤ 1/3) with disorder. Our results for Fe and Mo valence states are obtained using the Green functions and the renormalization perturbation expansion method. The model is based on a correlated electron picture with localized Fe-spins and conduction Mo-electrons interacting with the local spins via a double-exchange-type mechanism

  1. A constitutive model of nanocrystalline metals based on competing grain boundary and grain interior deformation mechanisms

    KAUST Repository

    Gurses, Ercan

    2011-12-01

    In this work, a viscoplastic constitutive model for nanocrystalline metals is presented. The model is based on competing grain boundary and grain interior deformation mechanisms. In particular, inelastic deformations caused by grain boundary diffusion, grain boundary sliding and dislocation activities are considered. Effects of pressure on the grain boundary diffusion and sliding mechanisms are taken into account. Furthermore, the influence of grain size distribution on macroscopic response is studied. The model is shown to capture the fundamental mechanical characteristics of nanocrystalline metals. These include grain size dependence of the strength, i.e., both the traditional and the inverse Hall-Petch effects, the tension-compression asymmetry and the enhanced rate sensitivity. © 2011 Elsevier B.V. All rights reserved.

  2. Photoluminescence Imaging of Large-Grain CdTe for Grain Boundary Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Steve; Allende Motz, Alyssa; Reese, Matthew O.; Burst, James M.; Metzger, Wyatt K.

    2015-06-14

    In this work, we use photoluminescence (PL) imaging to characterize CdTe grain boundary recombination. We use a silicon megapixel camera and green (532 nm) laser diodes for excitation. A microscope objective lens system is used for high spatial resolution and a field of view down to 190 um x 190 um. PL images of large-grain (5 to 50 um) CdTe samples show grain boundary and grain interior features that vary with processing conditions. PL images of samples in the as-deposited state show distinct dark grain boundaries that suggest high excess carrier recombination. A CdCl2 treatment leads to PL images with very little distinction at the grain boundaries, which illustrates the grain boundary passivation properties. Other process conditions are also shown, along with comparisons of PL images to high spatial resolution time-resolved PL carrier lifetime maps.

  3. Characterization of the Microstructure of the Compositionally Complex Alloy Al1Mo0.5Nb1Ta0.5Ti1Zr1 (Postprint)

    Science.gov (United States)

    2016-05-01

    grain boundaries of the Al1Mo0.5Nb1Ta0.5Ti1Zr1 sample. EBSD inverse pole figure (IPF) maps overlaid with image quality ( IQ ) micrographs, shown in Fig. 1...tomographic recon- structions using the STEM-HAADF and the Ta and Zr XEDS spectral im- ages are shown in Fig. 4. Themorphology of the disordered bcc phase

  4. Heat-affected zone microstructure and mechanical properties evolution for laser remanufacturing 35CrMoA axle steel

    Science.gov (United States)

    Feng, Xiangyi; Dong, Shiyun; Yan, Shixing; Liu, Xiaoting; Xu, Binshi; Pan, Fusheng

    2018-03-01

    In this article, by using orthogonal test the technological test was conducted and the optimum processing of the remanufacturing35CrMoA axle were obtained. The evolution of microstructure and mechanical property of HAZ were investigated. The microstructure of HAZ was characterized by means of OM and SEM. Meanwhile hardness distribution in HAZ and tensile property of cladding-HAZ-substrate samples were measured. The microstructure of cladding and HAZ were observed. The microsturcture evoltion and the mechanism of harden in the HAZ was discussed and revealed. The results indicated that the remanufacturing part has excellent strength due to grain refining and dispersive distribution of nanoscale cementite. The remanufacturing part will have uniform microstructure and hardness matching with that of 35CrMoA axle by using stress-relieving annealing at 580°.

  5. Reporting performance in MoS{sub 2}–TiO{sub 2} bilayer and heterojunction films based dye-sensitized photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    He, Zuoli, E-mail: wandaohzl@163.com; Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn; Xing, Yonglei; Liu, Xiaobin

    2016-07-05

    Three types of bilayer and heterojunction films photoanodes were designed and fabricated from green synthesized MoS{sub 2} and TiO{sub 2} nanoparticles (NPs), and then the dye-sensitized solar cells based on these various films photoanodes were investigated. Results demonstrated that layered semiconductor MoS{sub 2} could be a viable material candidate for solar cell applications due to its superior photoelectric characteristics. The DSSCs from the MoS{sub 2}@TiO{sub 2} heterojunction film photoanode exhibit the highest solar energy conversion efficiency of 6.02% under AM 1.5G simulated solar irradiation, which is 1.5 times higher than that of the cell from pure TiO{sub 2} film photoanode. MoS{sub 2}–TiO{sub 2} heterojunction at the interface helps MoS{sub 2} NPs to efficiently collect the photo-injected electrons from TiO{sub 2} NPs, thus reduce charge recombination at both the NPs-electrolyte and NPs-dye interfaces. These advantages together with collecting or transferring injected electrons abilities by combining the improved light absorption and the large dye-loading capacity of such structural NPs films, rendering the MoS{sub 2}–TiO{sub 2} composite photoelectrode superior potential for DSSCs applications. - Highlights: • MoS{sub 2} and TiO{sub 2} NPs were synthesized via green process using rape pollen grains as bio-templates. • DSSCs based on these various bilayer and heterojunction films photoanodes were investigated. • Enhanced η of MoS{sub 2}@TiO{sub 2} based DSSCs was related to its strong light adsorption ability. • The mechanism of electron transport in these various films photoanodes was proposed.

  6. Synthesis of Fine Mo2C Powder from Prereduced Mo in Undiluted CH4 Flow

    Science.gov (United States)

    Cetinkaya, S.; Eroglu, S.

    2017-10-01

    The carburization behavior of prereduced Mo was investigated in undiluted CH4 flow at 900-1000 K. Prior to the experiments, equilibrium thermodynamic analysis was carried out in the Mo-C-H system. The products were characterized by mass measurement, x-ray diffraction and scanning electron microscopy techniques. A single Mo2C phase was obtained within 45 min, 5 min, and 2.5 min at 900 K, 950 K, and 1000 K, respectively, at CH4 contents higher than the predicted ones. The reasons for this behavior were discussed in terms of CH4 stability, open tube flow, and self-created atmosphere in the powder bed. The fractional conversion-time curves indicated that the carburization kinetics followed a linear rate law. The Mo2C crystallite size (26-37 nm) and platelet thickness (50-100 nm) were found to be smaller than those of the parent Mo phase. These findings were attributable to the defects formed as a result of stresses associated with the reduction and the carburization.

  7. A density-functional study of the structures, binding energies and magnetic moments of the clusters Mo{sub N} (N = 2-13), Mo{sub 12}Fe, Mo{sub 12}Co and Mo{sub 12}Ni

    Energy Technology Data Exchange (ETDEWEB)

    Aguilera-Granja, F [Instituto de Fisica, Universidad Autonoma de San Luis PotosI, SLP 78000 (Mexico); Vega, A [Departamento de Fisica Teorica, Atomica, y Optica, Universidad de Valladolid, E-47011 Valladolid (Spain); Gallego, L J [Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

    2008-04-09

    We report the results of density-functional calculations of the structures, binding energies and magnetic moments of the clusters Mo{sub N} (N = 2-13), Mo{sub 12}Fe, Mo{sub 12}Co and Mo{sub 12}Ni that were performed using the SIESTA method within the generalized gradient approximation for exchange and correlation. For pure Mo{sub N} clusters, we obtain collinear magnetic structures in all cases, even when the self-consistent calculations were started from non-collinear inputs. Our results for these clusters show that both linear, planar and three-dimensional clusters have a strong tendency to form dimers. In general, even-numbered clusters are more stable than their neighbouring odd-numbered clusters because they can accommodate an integer number of tightly bound dimers. As a consequence, the binding energies of pure Mo{sub N} clusters, in their lowest-energy states, exhibit an odd-even effect in all dimensionalities. Odd-even effects are less noticeable in the magnetic moments than in the binding energies. When comparing our results for pure Mo clusters with those obtained recently by other authors, we observe similarities in some cases, but striking differences in others. In particular, the odd-even effect in three-dimensional Mo clusters was not observed before, and our results for some clusters (e.g. for planar Mo{sub 3} and Mo{sub 7} and for three-dimensional Mo{sub 7} and Mo{sub 13}) differ from those reported by other authors. For Mo{sub 12}Fe and Mo{sub 12}Ni, we obtain that the icosahedral configuration with the impurity atom at the cluster surface is more stable than the configuration with the impurity at the central site, while the opposite occurs in the case of Mo{sub 12}Co. In Mo{sub 12}Co and Mo{sub 12}Ni, the impurities exhibit a weak magnetic moment parallely coupled to the total magnetic moment of the Mo atoms, whereas in Mo{sub 12}Fe the impurity shows a high moment with antiparallel coupling.

  8. Static Recrystallized Grain Size of Coarse-Grained Austenite in an API-X70 Pipeline Steel

    Science.gov (United States)

    Sha, Qingyun; Li, Guiyan; Li, Dahang

    2013-12-01

    The effects of initial grain size and strain on the static recrystallized grain size of coarse-grained austenite in an API-X70 steel microalloyed with Nb, V, and Ti were investigated using a Gleeble-3800 thermomechanical simulator. The results indicate that the static recrystallized grain size of coarse-grained austenite decreases with decreasing initial grain size and increasing applied strain. The addition of microalloying elements can lead to a smaller initial grain size for hot deformation due to the grain growth inhibition during reheating, resulting in decreasing of static recrystallized grain size. Based on the experimental data, an equation for the static recrystallized grain size was derived using the least square method. The grain sizes calculated using this equation fit well with the measured ones compared with the equations for fine-grained austenite and for coarse-grained austenite of Nb-V microalloyed steel.

  9. Fate of Ice Grains in Saturn's Ionosphere

    Science.gov (United States)

    Hamil, O.; Cravens, T. E.; Reedy, N. L.; Sakai, S.

    2018-02-01

    It has been proposed that the rings of Saturn can contribute both material (i.e., water) and energy to its upper atmosphere and ionosphere. Ionospheric models require the presence of molecular species such as water that can chemically remove ionospheric protons, which otherwise are associated with electron densities that greatly exceed those from observation. These models adopt topside fluxes of water molecules. Other models have shown that ice grains from Saturn's rings can impact the atmosphere, but the effects of these grains have not been previously studied. In the current paper, we model how ice grains deposit both material and energy in Saturn's upper atmosphere as a function of grain size, initial velocity (at the "top" of the atmosphere, defined at an altitude above the cloud tops of 3,000 km), and incident angle. Typical grain speeds are expected to be roughly 15-25 km/s. Grains with radii on the order of 1-10 nm deposit most of their energy in the altitude range of 1,700-1,900 km, and can vaporize, depending on initial velocity and impact angle, contributing water mass to the upper atmosphere. We show that grains in this radius range do not significantly vaporize in our model at initial velocities lower than about 20 km/s.

  10. Diffusion mechanisms in grain boundaries in solids

    International Nuclear Information System (INIS)

    Peterson, N.L.

    1982-01-01

    A critical review is given of our current knowledge of grain-boundary diffusion in solids. A pipe mechanism of diffusion based on the well-established dislocation model seems most appropriate for small-angle boundaries. Open channels, which have atomic configurations somewhat like dislocation cores, probably play a major role in large-angle grain-boundary diffusion. Dissociated dislocations and stacking faults are not efficient paths for grain-boundary diffusion. The diffusion and computer modeling experiments are consistent with a vacancy mechanism of diffusion by a rather well-localized vacancy. The effective width of a boundary for grain-boundary diffusion is about two atomic planes. These general features of grain-boundary diffusion, deduced primarily from experiments on metals, are thought to be equally applicable for pure ceramic solids. The ionic character of many ceramic oxides may cause some differences in grain-boundary structure from that observed in metals, resulting in changes in grain-boundary diffusion behavior. 72 references, 5 figures

  11. Tracing magnetic fields with aligned grains

    International Nuclear Information System (INIS)

    Lazarian, A.

    2007-01-01

    Magnetic fields play a crucial role in various astrophysical processes, including star formation, accretion of matter, transport processes (e.g., transport of heat), and cosmic rays. One of the easiest ways to determine the magnetic field direction is via polarization of radiation resulting from extinction or/and emission by aligned dust grains. Reliability of interpretation of the polarization maps in terms of magnetic fields depends on how well we understand the grain-alignment theory. Explaining what makes grains aligned has been one of the big issues of the modern astronomy. Numerous exciting physical effects have been discovered in the course of research undertaken in this field. As both the theory and observations matured, it became clear that the grain-alignment phenomenon is inherent not only in diffuse interstellar medium or molecular clouds but also is a generic property of the dust in circumstellar regions, interplanetary space and cometary comae. Currently the grain-alignment theory is a predictive one, and its results nicely match observations. Among its predictions is a subtle phenomenon of radiative torques. This phenomenon, after having stayed in oblivion for many years after its discovery, is currently viewed as the most powerful means of alignment. In this article, I shall review the basic physical processes involved in grain alignment, and the currently known mechanisms of alignment. I shall also discuss possible niches for different alignment mechanisms. I shall dwell on the importance of the concept of grain helicity for understanding of many properties of grain alignment, and shall demonstrate that rather arbitrarily shaped grains exhibit helicity when they interact with gaseous and radiative flows

  12. The neutron capture process in the He shell in core-collapse supernovae: Presolar silicon carbide grains as a diagnostic tool for nuclear astrophysics

    Science.gov (United States)

    Pignatari, Marco; Hoppe, Peter; Trappitsch, Reto; Fryer, Chris; Timmes, F. X.; Herwig, Falk; Hirschi, Raphael

    2018-01-01

    Carbon-rich presolar grains are found in primitive meteorites, with isotopic measurements to date suggesting a core-collapse supernovae origin site for some of them. This holds for about 1-2% of presolar silicon carbide (SiC) grains, so-called Type X and C grains, and about 30% of presolar graphite grains. Presolar SiC grains of Type X show anomalous isotopic signatures for several elements heavier than iron compared to the solar abundances: most notably for strontium, zirconium, molybdenum, ruthenium and barium. We study the nucleosynthesis of zirconium and molybdenum isotopes in the He-shell of three core-collapse supernovae models of 15, 20 and 25 M⊙ with solar metallicity, and compare the results to measurements of presolar grains. We find the stellar models show a large scatter of isotopic abundances for zirconium and molybdenum, but the mass averaged abundances are qualitatively similar to the measurements. We find all models show an excess of 96Zr relative to the measurements, but the model abundances are affected by the fractionation between Sr and Zr since a large contribution to 90Zr is due to the radiogenic decay of 90Sr. Some supernova models show excesses of 95,97Mo and depletion of 96Mo relative to solar. The mass averaged distribution from these models shows an excess of 100Mo, but this may be alleviated by very recent neutron-capture cross section measurements. We encourage future explorations to assess the impact of the uncertainties in key neutron-capture reaction rates that lie along the n-process path.

  13. Equation of Motion for a Grain Boundary

    Science.gov (United States)

    Zhang, Luchan; Han, Jian; Xiang, Yang; Srolovitz, David J.

    2017-12-01

    Grain boundary (GB) migration controls many forms of microstructural evolution in polycrystalline materials. Recent theory, simulations, and experiments demonstrate that GB migration is controlled by the motion of discrete line defects or disconnections. We present a continuum equation of motion for grain boundary derived from the underlying discrete disconnection mechanism. We also present an equation of motion for the junctions where multiple grain boundaries meet—as is always the case in a polycrystal. The resulting equation of motion naturally exhibits junction drag—a widely observed phenomena in junction dynamics in solids and liquids.

  14. Statistical Theory of Normal Grain Growth Revisited

    International Nuclear Information System (INIS)

    Gadomski, A.; Luczka, J.

    2002-01-01

    In this paper, we discuss three physically relevant problems concerning the normal grain growth process. These are: Infinite vs finite size of the system under study (a step towards more realistic modeling); conditions of fine-grained structure formation, with possible applications to thin films and biomembranes, and interesting relations to superplasticity of materials; approach to log-normality, an ubiquitous natural phenomenon, frequently reported in literature. It turns out that all three important points mentioned are possible to be included in a Mulheran-Harding type behavior of evolving grains-containing systems that we have studied previously. (author)

  15. CASS Ferrite and Grain Structure Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Ruud, Clayton O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ramuhalli, Pradeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meyer, Ryan M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Diaz, Aaron A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-13

    This document summarizes the results of research conducted at Pacific Northwest National Laboratory (PNNL) to determine whether, based on experimental measurements, a correlation existed between grain structure in cast austenitic stainless steel (CASS) piping and ferrite content of the casting alloy. The motivation for this research lies in the fact that ultrasonic testing (UT) is strongly influenced by CASS grain structure; knowledge of this grain structure may help improve the ability to interpret UT responses, thereby improving the overall reliability of UT inspections of CASS components.

  16. Drying watery wheat grains by far infrared

    International Nuclear Information System (INIS)

    Suda, K.; Murata, K.; Hara, M.

    2004-01-01

    Summary A far infrared dryer was experimented to dry wheat grains for high performance and cost reduction. It is more efficient than a circulating dryer reducing drying time by 20% and fuel consumption by 20 - 30%. Whereas it takes more time and more fuel, when the drying rate is set at 1%/h. Moreover, on condition that the average drying rate is lower, it could decrease the rate of green wheat grains up to 3%. But green wheat grains did not disappear at all on the condition

  17. RF installation for the grain disinfestation

    CERN Document Server

    Zajtzev, B V; Kobetz, A F; Rudiak, B I

    2001-01-01

    The ecologically pure method of grain product disinfestations through the grain treatment with the RF electric field is described. The experimental data obtained showed that with strengths of the electrical RF field of E=5 kV/cm and frequency of 80 MHz the relative death rate is 100%.The time of the grain treatment it this case is 1 sec. The pulses with a duration of 600 mu s and repetition rate of 2 Hz were used, the duration of the front was 10 mu s. The schematic layout of installation with a productivity of 50 tones/h and power of 10 kW is given.

  18. Compressive Load Resistance Characteristics of Rice Grain

    OpenAIRE

    Sumpun Chaitep; Chaiy R. Metha Pathawee; Pipatpong Watanawanyoo

    2008-01-01

    Investigation was made to observe the compressive load property of rice gain both rough rice and brown grain. Six rice varieties (indica and japonica) were examined with the moisture content at 10-12%. A compressive load with reference to a principal axis normal to the thickness of the grain were conducted at selected inclined angles of 0°, 15°, 30°, 45°, 60° and 70°. The result showed the compressive load resistance of rice grain based on its characteristic of yield s...

  19. Mechanical intermixing of components in (CoMoNi)-based systems and the formation of (CoMoNi)/WC nanocomposite layers on Ti sheets under ball collisions

    Science.gov (United States)

    Romankov, S.; Park, Y. C.; Shchetinin, I. V.

    2017-11-01

    Cobalt (Co), molybdenum (Mo), and nickel (Ni) components were simultaneously introduced onto titanium (Ti) surfaces from a composed target using ball collisions. Tungsten carbide (WC) balls were selected for processing as the source of a cemented carbide reinforcement phase. During processing, ball collisions continuously introduced components from the target and the grinding media onto the Ti surface and induced mechanical intermixing of the elements, resulting in formation of a complex nanocomposite structure onto the Ti surface. The as-fabricated microstructure consisted of uniformly dispersed WC particles embedded within an integrated metallic matrix composed of an amorphous phase with nanocrystalline grains. The phase composition of the alloyed layers, atomic reactions, and the matrix grain sizes depended on the combination of components introduced onto the Ti surface during milling. The as-fabricated layer exhibited a very high hardness compared to industrial metallic alloys and tool steel materials. This approach could be used for the manufacture of both cemented carbides and amorphous matrix composite layers.

  20. Impact of Mismatch Angle on Electronic Transport Across Grain Boundaries and Interfaces in 2D Materials.

    Science.gov (United States)

    Majee, Arnab K; Foss, Cameron J; Aksamija, Zlatan

    2017-11-29

    We study the impact of grain boundaries (GB) and misorientation angles between grains on electronic transport in 2-dimensional materials. Here we have developed a numerical model based on the first-principles electronic bandstructure calculations in conjunction with a method which computes electron transmission coefficients from simultaneous conservation of energy and momentum at the interface to essentially evaluate GB/interface resistance in a Landauer formalism. We find that the resistance across graphene GBs vary over a wide range depending on misorientation angles and type of GBs, starting from 53 Ω μm for low-mismatch angles in twin (symmetric) GBs to about 10 20  Ω μm for 21° mismatch in tilt (asymmetric) GBs. On the other hand, misorientation angles have weak influence on the resistance across MoS 2 GBs, ranging from about 130 Ω μm for low mismatch angles to about 6000 Ω μm for 21°. The interface resistance across graphene-MoS 2 heterojunctions also exhibits a strong dependence on misorientation angles with resistance values ranging from about 100 Ω μm for low-mismatch angles in Class-I (symmetric) interfaces to 10 15  Ω μm for 14° mismatch in Class-II (asymmetric) interfaces. Overall, symmetric homo/heterojunctions exhibit a weak dependence on misorientation angles, while in MoS 2 both symmetric and asymmetric GBs show a gradual dependence on mismatch angles.

  1. Kinetics of cellular transformation and competing precipitation mechanisms during sub-eutectoid annealing of U10Mo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Saumyadeep; Devaraj, Arun; Kovarik, Libor; Arey, Bruce W.; Sweet, Lucas E.; Varga, Tamas; Lavender, Curt A.; Joshi, Vineet V.

    2017-11-01

    Transformation kinetics of metastable body-centered cubic γ-UMo phase in U-10 wt.percent Mo alloy during annealing at sub-eutectoid temperatures of 500C and 400C has been determined as a function of time using detailed microstructural characterization by scanning electron microscopy, X-ray diffraction analysis, scanning transmission electron microscopy, and atom probe tomography. Based on the results, we found that the phase transformation is initiated by cellular transformation at both the temperatures, which results in formation of a lamellar microstructure along prior γ-UMo grain boundaries.

  2. Gold nanoparticles on MoS2 layered crystal flakes

    International Nuclear Information System (INIS)

    Cao, Wei; Pankratov, Vladimir; Huttula, Marko; Shi, Xinying; Saukko, Sami; Huang, Zhongjia; Zhang, Meng

    2015-01-01

    Inorganic layered crystal MoS 2 is considered as one of the most promising and efficient semiconductor materials for future transistors, photoelectronics, and electrocatalysis. To boost MoS 2 -based material applications, one direction is to grow physically and chemically reactive nanoparticles onto MoS 2 . Here we report on a simple route to synthesis crystalized MoS 2 –Au complexes. The gold nanoparticles were grown on MoS 2 flakes through a wet method in the oxygen free environment at room temperature. Nanoparticles with diameters varying from 9 nm to 429 nm were controlled by the molar ratios of MoS 2 and HAuCl 4 precursors. MoS 2 host flakes keep intrinsic honeycomb layered structures and the Au nanoparticles cubic-center crystal microstructures. From product chemical states analysis, the synthesis was found driven by redox reactions between the sulphide and the chloroauric acid. Photoluminescence measurement showed that introducing Au nanoparticles onto MoS 2 stacks substantially prompted excitonic transitions of stacks, as an analogy for doping Si wafers with dopants. Such composites may have potential applications in wide ranges similar as the doped Si. - Highlights: • The Au nanoparticles were decorated on MoS 2 in oxygen free ambiences via a wet method. • The Au nanoparticles are size-controllable and crystalized. • Chemical reaction scheme was clarified. • The MoS 2 –Au complexes have strong photoluminescent properties

  3. Phase equilibria of the Mo-Al-Ho ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yitai; Chen, Xiaoxian; Liu, Hao [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Zhan, Yongzhong [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Guangxi Univ., Nanning (China). Center of Ecological Collaborative Innovation for Aluminum Industry

    2017-08-15

    Investigation into the reactions and phase equilibria of transition metal elements (i.e. Mo, Zr, Cr, V and Ti), Al and rare earths is academically and industrially important for the development of both refractory alloys and lightweight high-temperature materials. In this work, the equilibria of the Mo-Al-Ho ternary system at 773 K have been determined by using X-ray powder diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. A new ternary phase Al{sub 4}Mo{sub 2}Ho has been found and the other ternary phase Al{sub 43}Mo{sub 4}Ho{sub 6} is observed. Ten binary phases in the Al-Mo and Al-Ho systems, including Al{sub 17}Mo{sub 4} rather than Al{sub 4}Mo, have been determined to exist at 773 K. The homogeneity ranges of AlMo{sub 3} and Al{sub 8}Mo{sub 3} phase are 7.5 at.% and 1 at.%, respectively. According to the phase-disappearing method, the maximum solubility of Al in Mo is about 16 at.%.

  4. Nanostructured Mo-based electrode materials for electrochemical energy storage.

    Science.gov (United States)

    Hu, Xianluo; Zhang, Wei; Liu, Xiaoxiao; Mei, Yueni; Huang, Yunhui

    2015-04-21

    The development of advanced energy storage devices is at the forefront of research geared towards a sustainable future. Nanostructured materials are advantageous in offering huge surface to volume ratios, favorable transport features, and attractive physicochemical properties. They have been extensively explored in various fields of energy storage and conversion. This review is focused largely on the recent progress in nanostructured Mo-based electrode materials including molybdenum oxides (MoO(x), 2 ≤ x ≤ 3), dichalconides (MoX2, X = S, Se), and oxysalts for rechargeable lithium/sodium-ion batteries, Mg batteries, and supercapacitors. Mo-based compounds including MoO2, MoO3, MoO(3-y) (0 nanostructured Mo-based compounds, as well as their energy storage applications in lithium/sodium-ion batteries, Mg batteries, and pseudocapacitors. The relationship between nanoarchitectures and electrochemical performances as well as the related charge-storage mechanism is discussed. Moreover, remarks on the challenges and perspectives of Mo-containing compounds for further development in electrochemical energy storage applications are proposed. This review sheds light on the sustainable development of advanced rechargeable batteries and supercapacitors with nanostructured Mo-based electrode materials.

  5. Structural transformation of MoO3 nanobelts into MoS2 nanotubes

    International Nuclear Information System (INIS)

    Deepak, Francis Leonard; Mayoral, Alvaro; Yacaman, Miguel Jose

    2009-01-01

    The structural transformation of MoO 3 nanobelts into MoS 2 nanotubes using a simple sulfur source has been reported. This transformation has been extensively investigated using electron microscopic and spectroscopic techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), and energy-dispersive X-ray analysis (SEM-EDAX and TEM-EDX). The method described in this report will serve as a generic route for the transformation of other oxide nanostructures into the chalcogenide nanostructures. (orig.)

  6. Grotrian diagrams for highly ionized molybdenum Mo VI through Mo XLII

    International Nuclear Information System (INIS)

    Shirai, Toshizo; Sugar, J.; Wiese, W.L.

    1997-07-01

    Grotrian diagrams are presented to provide graphical overviews for 1,930 spectral lines of highly ionized molybdenum, Mo VI through Mo XLII. In the usual diagram display such as that by Bashkin and Stoner (North-Holland, Amsterdam, 1975), the density of transitions is often too high to allow each transition to be drawn separately. Here in our modified diagrams, the transitions are also represented by lines connecting the upper and lower energy levels, but the lower energy levels are extended and repeated for successive configurations as needed. As a sequence, dense packing is avoided and all lines in a multiplet can be accommodated. (author)

  7. Electronic and dielectric properties of MoS{sub 2}-MoX{sub 2} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Munish, E-mail: munishsharmahpu@live.com; Jamdagni, Pooja; Ahluwalia, P. K, E-mail: pk-ahluwalia7@yahoo.com [Department. of Physics, Himachal Pradesh University, Shimla, H. P., 171005 (India); Kumar, Ashok [Department. of Physics, Panjab University, Chandigarh, 160014 (India)

    2015-05-15

    We present a comparative study of electronic and dielectric properties of MoS{sub 2}−MoX{sub 2} heteostructures (where X=S, Se, Te) within the framework of density functional theory (DFT). Electronic band structure, real and imaginary part of dielectric function, electron energy loss spectra and static dielectric constant have been calculated for each system and compared with one another. A systematic decrease/increase in band gap/static dielectric constant is observed as the X changes from S to Te. These results provide a physical basis for the potential applications of these heterostructures in optoelectronic devices.

  8. Grains of Nonferrous and Noble Metals in Iron-Manganese Formations and Igneous Rocks of Submarine Elevations of the Sea of Japan

    Science.gov (United States)

    Kolesnik, O. N.; Astakhova, N. V.

    2018-01-01

    Iron-manganese formations and igneous rocks of submarine elevations in the Sea of Japan contain overlapping mineral phases (grains) with quite identical morphology, localization, and chemical composition. Most of the grains conform to oxides, intermetallic compounds, native elements, sulfides, and sulfates in terms of the set of nonferrous, noble, and certain other metals (Cu, Zn, Sn, Pb, Ni, Mo, Ag, Pd, and Pt). The main conclusion that postvolcanic hydrothermal fluids are the key sources of metals is based upon a comparison of the data of electron microprobe analysis of iron-manganese formations and igneous rocks dredged at the same submarine elevations in the Sea of Japan.

  9. The NGDC Seafloor Sediment Grain Size Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NGDC (now NCEI) Seafloor Sediment Grain Size Database contains particle size data for over 17,000 seafloor samples worldwide. The file was begun by NGDC in 1976...

  10. PROGRESS ON LARGE GRAIN AND SINGLE GRAIN NIOBIUM: INGOTS AND SHEET AND REVIEW OF PROGRESS ON LARGE GRAIN AND SINGLE GRAIN NIOBIUM CAVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Peter Kneisel

    2008-02-12

    Large grain and single crystal niobium has been proposed several years ago as an alternative material to poly-crystalline niobium for superconducting cavities, exhibiting potential advantages such as ¿stream-lined¿ procedures, reduced costs and better reproducibility in performance. Several major laboratories have investigated the use of large grain and single crystal material in the past years and the niobium producing industry has responded in providing ingot material with enlarged grain sizes. Besides a large number of single cell and multi-cell cavities from large grain niobium, several single crystal cavities have been fabricated and tested with good performances. This contribution will review the progress since the SRF workshop in 2005 in material processing and handling and in cavity performances.

  11. Barium Isotopes in Single Presolar Grains

    Science.gov (United States)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  12. Tsunami sediments and their grain size characteristics

    Science.gov (United States)

    Sulastya Putra, Purna

    2018-02-01

    Characteristics of tsunami deposits are very complex as the deposition by tsunami is very complex processes. The grain size characteristics of tsunami deposits are simply generalized no matter the local condition in which the deposition took place. The general characteristics are fining upward and landward, poor sorting, and the grain size distribution is not unimodal. Here I review the grain size characteristics of tsunami deposit in various environments: swale, coastal marsh and lagoon/lake. Review results show that although there are similar characters in some environments and cases, but in detail the characteristics in each environment can be distinguished; therefore, the tsunami deposit in each environment has its own characteristic. The local geological and geomorphological condition of the environment may greatly affect the grain size characteristics.

  13. Grain Elevators: New Source Performance Standards (NSPS)

    Science.gov (United States)

    The New Source Performance Standards (NSPS) for Grain Elevators aims to reduce particulate matter pollution. The new amendments seek to clarify definitions, and requirements, as well as propose new regulations on particulate matter emissions

  14. Grain operator miffed at port administration

    Index Scriptorium Estoniae

    2006-01-01

    Ventspils Grain Terminal saatis president Vaira Vike-Freibergale ja mitmetele ministritele kirja sõnumiga, et Ventspilsi Vabasadama (Ventspils Free Port) administratsiooni tegevus takistab terminali äritegevust

  15. Lifetime grain consumption and breast cancer risk.

    Science.gov (United States)

    Farvid, Maryam S; Cho, Eunyoung; Eliassen, A Heather; Chen, Wendy Y; Willett, Walter C

    2016-09-01

    We evaluated individual grain-containing foods and whole and refined grain intake during adolescence, early adulthood, and premenopausal years in relation to breast cancer risk in the Nurses' Health Study II. Grain-containing food intakes were reported on a baseline dietary questionnaire (1991) and every 4 years thereafter. Among 90,516 premenopausal women aged 27-44 years, we prospectively identified 3235 invasive breast cancer cases during follow-up to 2013. 44,263 women reported their diet during high school, and from 1998 to 2013, 1347 breast cancer cases were identified among these women. Cox proportional hazards regression was used to estimate relative risks (RR) and 95 % confidence intervals (95 % CI) of breast cancer for individual, whole and refined grain foods. After adjusting for known breast cancer risk factors, adult intake of whole grain foods was associated with lower premenopausal breast cancer risk (highest vs. lowest quintile: RR 0.82; 95 % CI 0.70-0.97; P trend = 0.03), but not postmenopausal breast cancer. This association was no longer significant after further adjustment for fiber intake. The average of adolescent and early adulthood whole grain food intake was suggestively associated with lower premenopausal breast cancer risk (highest vs lowest quintile: RR 0.74; 95 % CI 0.56-0.99; P trend = 0.09). Total refined grain food intake was not associated with risk of breast cancer. Most individual grain-containing foods were not associated with breast cancer risk. The exceptions were adult brown rice which was associated with lower risk of overall and premenopausal breast cancer (for each 2 servings/week: RR 0.94; 95 % CI 0.89-0.99 and RR 0.91; 95 % CI 0.85-0.99, respectively) and adult white bread intake which was associated with increased overall breast cancer risk (for each 2 servings/week: RR 1.02; 95 % CI 1.01-1.04), as well as breast cancer before and after menopause. Further, pasta intake was inversely associated with

  16. Relationships between microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr-1Zr alloy

    Science.gov (United States)

    Li, Z. Y.; Wu, G. Q.; Huang, Z.

    2018-03-01

    Through a statistical, quantitative analysis on microstructure of Ti-5Al-5Mo-5V-3Cr-1Zr (Ti55531) alloy, the relationships between microstructure and mechanical properties and heat treatment temperatures were investigated. The results show that in Widmanstätten structure, the size of β grain is greatly increased with increasing annealing temperature. Static toughness is related to grain boundary alpha phase discontinuity, the tensile strength is related to acicular alpha phase interface length and acicular alpha phase proportion. In duplex microstructure, the tensile strength is related to the equiaxed alpha proportion. Elongation, static toughness and crack forming work are related to the equiaxed alpha proportion and negatively related to secondary phase proportion. The microstructure can be described quantitatively and the mechanical properties can be predicted by analysis of microstructure.

  17. Grain breakage under uniaxial compression, through 3D DEM modelling

    Science.gov (United States)

    Nader, François; Silvani, Claire; Djeran-Maigre, Irini

    2017-06-01

    A breakable grain model is presented, using the concept of particles assembly. Grains of polyhedral shapes are generated, formed by joining together tetrahedral subgrains using cohesive bonds. Single grain crushing simulations are performed for multiple values of the intra-granular cohesion to study the effect on the grain's strength. The same effect of intra-granular cohesion is studied under oedometric compression on samples of around 800 grains, which allows the evaluation of grain breakage model on the macroscopic behaviour. Grain size distribution curves and grain breakage ratios are monitored throughout the simulations.

  18. The formation of small grains in shocks in the ISM

    Science.gov (United States)

    Jones, Anthony P.; Tielens, Alexander G. G. M.

    1994-01-01

    Carbonaceous and silicate grains swept up, and betatron accelerated, by supernova-generated shock waves in the interstellar medium are exposed to grain destructive processing. The degree of grain destruction is determined by the differential gas-grain and grain-grain velocities, which lead to sputtering of the grain surface and grain core disruption (deformation, vaporization and shattering), respectively. The threshold pressure for grain shattering in grain-grain collisions (100 k bar) is considerably lower than that for vaporization (approximately 5 M bar). Therefore, collisions between grains shatter large grains into smaller fragments (i.e., small grains and PAH's). Using a new algorithms for the destructive processes, it was possible to model the formation fo small grain fragments in grain-grain collisions in the warm phase of the interstellar medium. It was found that in one cycle through the warm medium (approximately 3 x 10(sup 6) years) of order 1-2% of the total grain mass is shattered into particles with radii of less than 50 A.

  19. Grain Contrast Imaging in UHV SLEEM

    Czech Academy of Sciences Publication Activity Database

    Mikmeková, Šárka; Hovorka, Miloš; Müllerová, Ilona; Man, O.; Pantělejev, L.; Frank, Luděk

    2010-01-01

    Roč. 51, č. 2 (2010), s. 292-296 ISSN 1345-9678 R&D Projects: GA MŠk OE08012 Institutional research plan: CEZ:AV0Z20650511 Keywords : scanning low energy electron microscopy * electron backscatter diffraction (EBSD) * grain contrast * ultra-fine grained materials Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.779, year: 2010 http://www.jim.or.jp/journal/e/51/02/292.html

  20. Quality of 99mTcO4- from 99Mo Produced by 100Mo(n,2n)99Mo

    Science.gov (United States)

    Nagai, Yasuki; Nakahara, Yuto; Kawabata, Masako; Hatsukawa, Yuichi; Hashimoto, Kazuyuki; Saeki, Hideya; Motoishi, Shoji; Ohta, Akio; Shiina, Takayuki; Kawauchi, Yukimasa

    2017-05-01

    The pharmaceutical quality of 99mTc pertechnetate solution obtained from 99Mo, the 100Mo(n,2n) reaction product, was investigated for the first time with an emphasis on the nonradioactive Mo content and endotoxin concentration. They were less than the tolerance dose given in international guidelines and the established upper limit in an international pharmacopoeia, respectively. Four other quality control tests commonly used for a commercially available 99mTc pertechnetate solution also demonstrated to meet the United States Pharmacopeia requirements. The results strongly support that the thermochromatographic separation method used to separate 99mTc from 99Mo can be a promising substitute for the fission product 99Mo.

  1. Radiochemical purity of Mo and Tc solution obtained after irradiation and dissolution of Mo-100-enriched and ultra-high-purity natural Mo disks

    Energy Technology Data Exchange (ETDEWEB)

    Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States); Gromov, Roman [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey D. [Argonne National Lab. (ANL), Argonne, IL (United States); Rotsch, David A. [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-01

    Four irradiations of ultra-high-purity natural Mo targets and one irradiation using 97.4% Mo-100-enriched material were performed. The purpose of these irradiations was to determine whether the presence of Sn stabilizer in the H2O2 used for the dissolution of sintered Mo disks can affect the radiochemical purity of the final K2MoO4 in 5M KOH solution. Results from radiochemical purity tests performed using thin-layer paper chromatography show that even 2– 3× excess of Sn-stabilized H2O2 typically used for dissolution of sintered Mo disks did not affect the radiochemical purity of the final product.

  2. Pollen grains are efficient cloud condensation nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pope, F D, E-mail: fdp21@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2010-10-15

    This letter presents a laboratory study investigating the ability of pollen grains to act as cloud condensation nuclei. The hygroscopicity of pollen is measured under subsaturated relative humidities using an electrodynamic balance. It is found, along with other results, that pollen exhibits bulk uptake of water under subsaturated conditions. Through the use of an environmental scanning electron microscope it was observed that the surface of pollen is wettable at high subsaturated humidities. The hygroscopic response of the pollen to subsaturated relative humidities is parametrized using {kappa}-Koehler theory and values of the parameter {kappa} for pollen are between 0.05 and 0.1. It is found that while pollen grains are only moderately hygroscopic, they can activate at critical supersaturations of 0.001% and lower, and thus pollen grains will readily act as cloud condensation nuclei. While the number density of pollen grains is too low for them to represent a significant global source of cloud condensation nuclei, the large sizes of pollen grains suggest that they will be an important source of giant cloud condensation nuclei. Low temperature work using the environmental scanning electron microscope indicated that pollen grains do not act as deposition ice nuclei at temperatures warmer than - 15 deg. C.

  3. Coarse Graining Shannon and von Neumann Entropies

    Directory of Open Access Journals (Sweden)

    Ana Alonso-Serrano

    2017-05-01

    Full Text Available The nature of coarse graining is intuitively “obvious”, but it is rather difficult to find explicit and calculable models of the coarse graining process (and the resulting entropy flow discussed in the literature. What we would like to have at hand is some explicit and calculable process that takes an arbitrary system, with specified initial entropy S, and that monotonically and controllably drives the entropy to its maximum value. This does not have to be a physical process, in fact for some purposes it is better to deal with a gedanken-process, since then it is more obvious how the “hidden information” is hiding in the fine-grain correlations that one is simply agreeing not to look at. We shall present several simple mathematically well-defined and easy to work with conceptual models for coarse graining. We shall consider both the classical Shannon and quantum von Neumann entropies, including models based on quantum decoherence, and analyse the entropy flow in some detail. When coarse graining the quantum von Neumann entropy, we find it extremely useful to introduce an adaptation of Hawking’s super-scattering matrix. These explicit models that we shall construct allow us to quantify and keep clear track of the entropy that appears when coarse graining the system and the information that can be hidden in unobserved correlations (while not the focus of the current article, in the long run, these considerations are of interest when addressing the black hole information puzzle.

  4. Facile synthesis of stable structured MoS{sub 2}-Mo-CNFs heteroarchitecture with enhanced hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Qionghua [Research Institute for New Materials Technology, Chongqing University of Arts and Sciences, Chongqing 402160 (China); Faculty of Material and Energy, South West University, Chongqing 400700 (China); Yao, Yucen [Research Institute for New Materials Technology, Chongqing University of Arts and Sciences, Chongqing 402160 (China); Liu, Bitao, E-mail: liubitao007@163.com [Research Institute for New Materials Technology, Chongqing University of Arts and Sciences, Chongqing 402160 (China); Peng, Lingling; Yan, Hengqing; Hou, Zhupei; Wang, Jun [Research Institute for New Materials Technology, Chongqing University of Arts and Sciences, Chongqing 402160 (China); Lin, Yue, E-mail: linyue@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Anhui 230026 (China)

    2017-06-01

    3D structured MoS{sub 2} are grown in-situ on Mo particles embedded carbon nanofibers (CNFs) via a hydrothermal method. Due to this special structure, the bonding and effective electron delivery between CNFs and MoS{sub 2} are both enhanced, and which will exhibits a better hydrogen evolution activity. The onset potential of this MoS{sub 2}-Mo-CNFs catalyst will decreased to 60 mV compared to the 90 mV for the MoS{sub 2}-CNFs. And its current density nearly no change with 5000 cycles which is better than the 32.3% decrease of MoS{sub 2}-CNFs at η = 300 mV (V vs RHE). - Highlights: • Newly structured MoS{sub 2}-Mo-CNFs with effectively connection between MoS{sub 2} and CNFs successfully synthesized. • This structure can enhance the charge transfer and significantly increase electrocatalytic efficiency. • Nearly no HER activity loss after 5000 CV cycles.

  5. Variability for grain mold resistance in sorghum F3 progenies of red × red and red × white grain crosses

    OpenAIRE

    Vinay patted, M. Y. Kamatar and S. K. Deshpande

    2011-01-01

    The present investigation was carried out to estimate the nature and magnitude of genetic variability for yield and grain moldresistance in 99 sorghum F3 progenies of red × red and red × white crosses including parents and checks. Variation for grain moldassociated traits was analyzed with respect to grain hardness, panicle compactness, grain colour, glume length and glume colour.Among 99 F3 progenies 30 progenies exhibited partly hard grains and 19 progenies had hard grains and which exhibit...

  6. Control and Characterization of Individual Grains and Grain Boundaries in Graphene Grown by Chemical Vapour Deposition

    Science.gov (United States)

    2011-06-01

    field (B). Figure 5c presents low temperature (4.3 K) magnetoresistance (Rxx(B)) measurements across the grain boundary compared to Rxx(B) measured within...voltage leads labelled in the legend. c, Four-terminal magnetoresistance (Rxx) measured at 4.3 K within each graphene grain and across the grain boundary...graphene nanoribbons. Nature 444, 347–349 (2006). 37. Huang, M. Y. et al. Phonon softening and crystallographic orientation of strained graphene studied by

  7. Atomic scale onset of Al adhesion on Mo2BC

    International Nuclear Information System (INIS)

    Bolvardi, Hamid; Music, Denis; Schneider, Jochen M.

    2015-01-01

    We have explored interfacial interactions between a Mo–C terminated Mo 2 BC(040) surface and an Al cluster using ab initio molecular dynamics. The Al cluster is disrupted and wets the Mo 2 BC(040) surface. This can be understood based on the electronic structure. Across the Al–MoC interface C s–Al s hybridized states are formed. These bonds are stronger than the Al–Al intra-cluster bonds. Hence, the onset of Al adhesion is caused by bond formation across the Al–MoC interface. - Highlights: • Interfacial interactions between Mo 2 BC and an Al cluster were explored. • Al forms bonds to C constituting the onset of Al adhesion on Mo 2 BC. • These data are relevant for other carbide coatings

  8. Na2MoO2As2O7

    Directory of Open Access Journals (Sweden)

    Raja Jouini

    2012-12-01

    Full Text Available Disodium molybdenum dioxide diarsenate, Na2MoO2As2O7, has been synthesized by a solid-state reaction. The structure is built up from MoAs2O12 linear units sharing corners to form a three-dimensional framework containing tunnels running along the a-axis direction in which the Na+ cations are located. In this framework, the AsV atoms are tetrahedrally coordinated and form an As2O7 group. The MoVI atom is displaced from the center of an octahedron of O atoms. Two Na+ cations are disordered about inversion centres. Structural relationships between different compounds: A2MoO2As2O7 (A = K, Rb, AMOP2O7 (A = Na, K, Rb; M = Mo, Nb and MoP2O7 are discussed.

  9. Phase relations in the system CuMoS

    Science.gov (United States)

    Dawei, H.; Chang, L.L.Y.; Knowles, C.R.

    1990-01-01

    Phase relations in the system CuMoS were studied in the temperature range 500-1000 ??C by using the conventional sealed, evacuated glass capsule technique. Reflected-light microscopy, X-ray powder diffraction and electron microprobe analysis were used for phase characterization. The chevrel-type phase, CuxMo3S4, is stable above 600??C, and forms equilibrium assemblages with the cubic Cu2S solid solution, copper, molybdenum, Mo2S3 and MoS2. Its solid solution ranges from Cu1.50-2.00Mo3S4 at 700??C to Cu1.22-2.00Mo3S4 at 1000 ??C. ?? 1990.

  10. Electrochemical deposition and characterization of Ni-Mo alloy powders

    Directory of Open Access Journals (Sweden)

    M.G. Pavlović

    2007-12-01

    Full Text Available Electrodeposition of Ni-Mo alloy powders from ammonium sulfate and ammonium chloride containing electrolytes of different Ni/Mo ions concentration ratios was investigated by polarization measurements. The morphology, chemical composition and phase composition of electrodeposited Ni-Mo alloy powders were investigated using DSC, TGA, SEM, EDS and XRD analysis. EDS results showed that powder composition depends on Ni/Mo ions concentration ratio, as well as on the position where the EDS analysis was performed. As-deposited alloy powders were nanocrystalline showing no XRD peaks with undefined morphology (SEM. After recrystallization for 2 h in N2 atmosphere at 600°C the presence of NiMoO4 phase was identified in the powder electrodeposited from chloride electrolyte at the Ni/Mo ions concentration ratio 1/3, with well defined crystalline powder particles.

  11. U-Mo fuel qualification program in HANARO

    International Nuclear Information System (INIS)

    Lee, K.H.; Lee, C.S.; Kim, H.R.; Kuk, I.H.; Kim, C.K.

    2000-01-01

    Atomized U-Mo fuel has shown good performance from the results of previous out-of-pile tests and post-irradiation examinations. A qualification program of rod type U-Mo fuel is in progress and the fuel will be irradiated in HANARO. 6 gU/cm 3 U-7Mo, U-8Mo and U-9Mo are considered in this program. The laboratory test results of porosity, mechanical property, thermal conductivity, and thermal compatibility test are discussed in this paper. In parallel with this qualification program, the feasibility study on the core conversion from the present U 3 Si fuel to U-Mo in HANARO will be initiated to provide technical bases for the policy making. Several options of core conversion for HANARO are proposed and each option will be addressed briefly in terms of the operation policy, fuel management, and licensing of HANARO. (author)

  12. Crystallization of MoO2 from gaseous phase

    International Nuclear Information System (INIS)

    Klinkova, L.A.; Skrebkova, E.D.

    1977-01-01

    The effect of the conditions of growing MoO 2 crystals from a gaseous phase in the presence of iodine on morphology and quality of the crystals has been studied. MoO 2 and Mo+MoO 3 have been used as an initial charge; iodine concentration has been changed from 0.5 to 10 mg/cm 3 . The quality of the crystals has been evaluated by the ratio between the resistance at room and helium temperatures. Optimum temperature of the crystallization zone on growing MoO 2 crystals is 850 deg since at that temperature the value of the residual resistance of the crystals is maximum. Iodine concentration must not exceed 0.5-2 mg/cm 3 . The obtained MoO 2 crystals possess good surface area; dislocation density does not exceed 10 -3 cm -2

  13. Development of microstructure and mechanical properties during annealing of a cold-swaged Co-Cr-Mo alloy rod.

    Science.gov (United States)

    Mori, Manami; Sato, Nanae; Yamanaka, Kenta; Yoshida, Kazuo; Kuramoto, Koji; Chiba, Akihiko

    2016-12-01

    In this study, we investigated the evolution of the microstructure and mechanical properties during annealing of a cold-swaged Ni-free Co-Cr-Mo alloy for biomedical applications. A Co-28Cr-6Mo-0.14N-0.05C (mass%) alloy rod was processed by cold swaging, with a reduction in area of 27.7%, and then annealed at 1173-1423K for various periods up to 6h. The duplex microstructure of the cold-swaged rod consisted of a face-centered cubic γ-matrix and hexagonal closed-packed ε-martensite developed during cold swaging. This structure transformed nearly completely to the γ-phase after annealing and many annealing twin boundaries were observed as a result of the heat treatment. A small amount of the ε-phase was identified in specimens annealed at 1173K. Growth of the γ-grains occurred with increasing annealing time at temperatures ≥1273K. Interestingly, the grain sizes remained almost unchanged at 1173K and a very fine grain size of approximately 8μm was obtained. The precipitation that occurred during annealing was attributed to the limited grain coarsening during heat treatment. Consequently, the specimens treated at this temperature showed the highest tensile strength and lowest ductility among the specimens prepared. An elongation-to-failure value larger than 30% is sufficient for the proposed applications. The other specimens treated at higher temperatures possessed similar tensile properties and did not show any significant variations with different annealing times. Optimization of the present rod manufacturing process, including cold swaging and interval annealing heat treatment, is discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Selection of common bean lines with high grain yield and high grain calcium and iron concentrations

    Directory of Open Access Journals (Sweden)

    Nerinéia Dalfollo Ribeiro

    2014-02-01

    Full Text Available Genetic improvement of common bean nutritional quality has advantages in marketing and can contribute to society as a food source. The objective of this study was to evaluate the genetic variability for grain yield, calcium and iron concentrations in grains of inbred common bean lines obtained by different breeding methods. For this, 136 F7 inbred lines were obtained using the Pedigree method and 136 F7 inbred lines were obtained using the Single-Seed Descent (SSD method. The lines showed genetic variability for grain yield, and concentrations of calcium and iron independently of the method of advancing segregating populations. The Pedigree method allows obtaining a greater number of lines with high grain yield. Selection using the SSD method allows the identification of a larger number of lines with high concentrations of calcium and iron in grains. Weak negative correlations were found between grain yield and calcium concentration (r = -0.0994 and grain yield and iron concentration (r = -0.3926. Several lines show genetic superiority for grain yield and concentrations of calcium and iron in grains and their selection can result in new common bean cultivars with high nutritional quality.

  15. Mechanism of secondary recrystallization of Goss grains in grain-oriented electrical steel.

    Science.gov (United States)

    Hayakawa, Yasuyuki

    2017-01-01

    Since its invention by Goss in 1934, grain-oriented (GO) electrical steel has been widely used as a core material in transformers. GO exhibits a grain size of over several millimeters attained by secondary recrystallization during high-temperature final batch annealing. In addition to the unusually large grain size, the crystal direction in the rolling direction is aligned with , which is the easy magnetization axis of α-iron. Secondary recrystallization is the phenomenon in which a certain very small number of {110} (Goss) grains grow selectively (about one in 10 6 primary grains) at the expense of many other primary recrystallized grains. The question of why the Goss orientation is exclusively selected during secondary recrystallization has long been a main research subject in this field. The general criterion for secondary recrystallization is a small and uniform primary grain size, which is achieved through the inhibition of normal grain growth by fine precipitates called inhibitors. This paper describes several conceivable mechanisms of secondary recrystallization of Goss grains mainly based on the selective growth model.

  16. IEA Mobility Model (MoMo) and its use in the ETP 2008

    International Nuclear Information System (INIS)

    Fulton, Lew; Cazzola, Pierpaolo; Cuenot, Francois

    2009-01-01

    The IEA published 'Energy Technology Perspectives' (ETP) in June 2008. That document reports on IEA scenarios for baseline and low-CO 2 alternative scenarios to 2050, across the energy economy. The study included creating scenarios for transport, using the IEA Mobility Model (MoMo). This paper reports on the transport-related ETP scenarios and describes the model used in the analysis. According to the ETP Baseline scenario, world transport energy use and CO 2 emissions will more than double by 2050. In the most challenging scenario, called 'BLUE', transport emissions are reduced by 70% in 2050 compared to their baseline level in that year (and about 25% below their 2005 levels). There are several versions of the BLUE scenario, but all involve: a 50% or greater improvement in LDV efficiency, 30-50% improvement in efficiency of other modes (e.g. trucks, ships and aircraft), 25% substitution of liquid fossil fuels by biofuels, and considerable penetration of electric and/or fuel-cell vehicles. In the second half of this paper, an overview of the MoMo model is provided. Details on the complete analysis are contained in the ETP 2008 document, available at (www.iea.org). Details of the LDV fuel economy analysis are contained in a separate paper in this collection.

  17. Intermediate report of MoReMo. Modelling resilience for maintenance and outage

    International Nuclear Information System (INIS)

    Oedewald, P.; Macchi, L.; Axelsson, C.; Eitrheim, M.H.R.

    2012-02-01

    Resilience Engineering (RE) is a new approach to safety that helps organisations and individuals adapt to unforeseen events and long-term changes. Such an approach is needed by nuclear power plants (NPPs) as they face demanding modification projects, high staff turnover and increased pressures to maintain and improve safety. The goal of the Modelling Resilience for Maintenance and Outage (MoReMO) project is to develop and test models and methods to identify and analyse resilience in safety-critical activities in natural everyday settings. In 2011, we have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. The project has collected data through observations, interviews and document reviews at two NPPs. Together, the four approaches have provided valuable insights for understanding the rationale behind work practices, their effects on safety, and the support of flexibility and adaptability. In 2012, the MoReMO project will complete the data collection and integrate results on how resilience can be operationalized in practical safety management tools for the companies. (Author)

  18. Intermediate report of MoReMo. Modelling resilience for maintenance and outage

    Energy Technology Data Exchange (ETDEWEB)

    Oedewald, P.; Macchi, L. (VTT Technical Research Centre of Finland (Finland)); Axelsson, C. (Ringhals AB, Vattenfall AB (Sweden)); Eitrheim, M.H.R. (Institute for Energy Technology (Norway))

    2012-02-15

    Resilience Engineering (RE) is a new approach to safety that helps organisations and individuals adapt to unforeseen events and long-term changes. Such an approach is needed by nuclear power plants (NPPs) as they face demanding modification projects, high staff turnover and increased pressures to maintain and improve safety. The goal of the Modelling Resilience for Maintenance and Outage (MoReMO) project is to develop and test models and methods to identify and analyse resilience in safety-critical activities in natural everyday settings. In 2011, we have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. The project has collected data through observations, interviews and document reviews at two NPPs. Together, the four approaches have provided valuable insights for understanding the rationale behind work practices, their effects on safety, and the support of flexibility and adaptability. In 2012, the MoReMO project will complete the data collection and integrate results on how resilience can be operationalized in practical safety management tools for the companies. (Author)

  19. Evolution of Dynamic Recrystallization in 35CrMo Steel During Hot Deformation

    Science.gov (United States)

    Xiao, Zhengbing; Huang, Yuanchun; Liu, Yu

    2018-03-01

    To better understand the dynamic recrystallization (DRX) behavior of 35CrMo steel during hot deformation, a series of isothermal compression tests were carried out at different temperatures and strain rates. Using a constitutive equation built from the data obtained and the Arrhenius equation, the activation energy for hot deformation was determined through regression to be 342.69 kJ/mol. A model of the DRX kinetics was also constructed to characterize the influence of accumulated strain, temperature and strain rate on DRX evolution, which revealed that lower temperatures and higher strain rates require greater strain to achieve the same DRX volume fraction. Optical examination of the microstructure after deformation confirmed that this model accurately reflects reality and that grain size varies directly with deformation temperature, but inversely with strain rate.

  20. Basic investigation for life assessment technology of modified 9CR-1Mo steel

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, Hiroyuki [Science Univ. of Tokyo (Japan); Ohtani, Ryuichi [Kyoto Univ. (Japan); Fujii, Kazuya [Japan Power Engineering and Inspection Corp., Tokyo (Japan); Kimura, Kazushige; Ishii, Ryuichi; Fujiyama, Kazunari; Hongo, Shigetada; Iseki, Takashi; Uchida, Hiroshi [Toshiba Corp., Kawasaki, Kanagawa (Japan)

    1998-11-01

    For the basic study of life assessment technologies for aged components made of mod.9Cr-1Mo steel, specimens were artificially deteriorated by aging, creep and fatigue tests at elevated temperatures. And metallurgical and mechanical properties were examined. The change in the precipitates caused the decrease in toughness. The creep damage in base metal corresponded to the decrease in hardness. The fatigue damage in base metal correlated to the maximum length of a crack among micro-cracks initiated during fatigue cycle. In the welded joint, the creep fracture occurred by the formation and growth of voids in the fine grained region of HAZ near base metal. The creep damage was associated with the increase in both number and area fraction of voids. (orig.)

  1. Computational identification of MoRFs in protein sequences.

    Science.gov (United States)

    Malhis, Nawar; Gsponer, Jörg

    2015-06-01

    Intrinsically disordered regions of proteins play an essential role in the regulation of various biological processes. Key to their regulatory function is the binding of molecular recognition features (MoRFs) to globular protein domains in a process known as a disorder-to-order transition. Predicting the location of MoRFs in protein sequences with high accuracy remains an important computational challenge. In this study, we introduce MoRFCHiBi, a new computational approach for fast and accurate prediction of MoRFs in protein sequences. MoRFCHiBi combines the outcomes of two support vector machine (SVM) models that take advantage of two different kernels with high noise tolerance. The first, SVMS, is designed to extract maximal information from the general contrast in amino acid compositions between MoRFs, their surrounding regions (Flanks), and the remainders of the sequences. The second, SVMT, is used to identify similarities between regions in a query sequence and MoRFs of the training set. We evaluated the performance of our predictor by comparing its results with those of two currently available MoRF predictors, MoRFpred and ANCHOR. Using three test sets that have previously been collected and used to evaluate MoRFpred and ANCHOR, we demonstrate that MoRFCHiBi outperforms the other predictors with respect to different evaluation metrics. In addition, MoRFCHiBi is downloadable and fast, which makes it useful as a component in other computational prediction tools. http://www.chibi.ubc.ca/morf/. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Atomic structure calculations of Mo XV-XL

    International Nuclear Information System (INIS)

    Kubo, Hirotaka; Sugie, Tatsuo; Shiho, Makoto; Suzuki, Yasuo; Ishii, Keishi; Maeda, Hikosuke.

    1986-06-01

    Energy levels and oscillator strengths were calculated for Mo XV - Mo XL. The computer program for atomic structure calculation, developed by Dr. Robert D. Cowan, Los Alamos National Laboratory, was used in the present work. The scaled energy parameters were empirically determined from the observed spectral data. We present wavelengths and transition probabilities of Mo XV-XL. Energy levels and spectral patterns are presented in figures that are useful for the identification of spectral lines. (author)

  3. Structural and magnetic properties of NdFeB and NdFeB/Fe films with Mo addition

    Energy Technology Data Exchange (ETDEWEB)

    Urse, M; Grigoras, M; Lupu, N; Chiriac, H, E-mail: urse@phys-iasi.ro [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)

    2011-07-06

    The influence of the Mo addition on the microstructure and magnetic properties of Nd-Fe-B and Nd-Fe-B/Fe films was studied. The coercivity is a key parameter in the control of technical performances of Nd-Fe-B films. A small amount of about 1 at.% Mo can enhance the coercivity of Nd-Fe-B film by controlling the growth of soft and hard magnetic grains. A coercivity of 22.1 kOe, a remanence ratio, M{sub r}/M{sub s}, of 0.83 and a maximum energy product of 8 MGOe were obtained for Ta/[NdFeBMo(1at.%)(540nm)/Ta films annealed at 650{sup 0}C for 20 minutes due to Mo precipitates formed at the Nd{sub 2}Fe{sub 14}B phase boundaries which prevent the nucleation and expansion of the magnetic domains. Simultaneous use of Mo as addition and the stratification of Nd-Fe-B-Mo films using Fe as spacer layer are important tools for the improvement of the hard magnetic properties of Nd-Fe-B films. The Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta multilayer film annealed at 620{sup 0}C exhibits an increase in the coercivity from 12.1 kOe to 22.8 kOe, in the remanence ratio from 0.77 to 0.80, and in the maximum energy product from 4.5 to 7.1 MGOe in comparison with Ta/Nd-Fe-B/Ta film. As compared to Ta/Nd-Fe-B/Ta film, the Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta film presents a decrease in the crystallization temperature of about 30{sup 0}C.

  4. Effect of rapid thermal annealing on the Mo back contact properties for Cu2ZnSnSe4 solar cells

    International Nuclear Information System (INIS)

    Placidi, Marcel; Espindola-Rodriguez, Moises; Lopez-Marino, Simon; Sanchez, Yudania; Giraldo, Sergio; Acebo, Laura; Neuschitzer, Markus; Alcobé, Xavier; Pérez-Rodríguez, Alejandro; Saucedo, Edgardo

    2016-01-01

    The effect of a rapid thermal process (RTP) on the molybdenum (Mo) back contact for Cu 2 ZnSnSe 4 (CZTSe) solar cells is here investigated. It is shown that the annealing of the Mo layer during 5 min at 550 °C, not only improves the crystalline quality of the back contact (avoiding the absorber decomposition at this region because Mo becomes more resistant to the selenization), but also helps achieving higher crystalline quality of the absorber with bigger grains, reducing the current leakage through the heterojunction. We demonstrate that this is related to the relaxation of the compressive stress of the CZTSe absorber, when synthesized on the RTP annealed substrates. CZTSe solar cells prepared on annealed Mo films exhibited higher short circuit current densities and higher open circuit voltages, resulting in 10% and 33% higher fill factors and efficiencies. - Highlights: • An RTP annealing applied for the first time on Mo for CZTSe solar cells. • Clear improvement of the efficiency from 5.7 to 7.6% with RTP treatment. • Discussion of this improvement with adequate material/device characterizations. • Stress-induced defects responsible of the electrical leakage are revealed.

  5. Formation of ball-milled Fe-Mo nanostructured powders

    Energy Technology Data Exchange (ETDEWEB)

    Moumeni, H. [Laboratoire de Magnetisme et de Spectroscopie des Solides, LM2S, Departement de Physique, Faculte des Sciences, Universite de Annaba, B.P. 12, 23000 Annaba-Algerie (Algeria) and Departement de Physique, Faculte des Sciences et de l' Ingenierie, Universite de Guelma, B.P. 401, 24000 Guelma-Algerie (Algeria)]. E-mail: hmoumeni@yahoo.fr; Alleg, S. [Laboratoire de Magnetisme et de Spectroscopie des Solides, LM2S, Departement de Physique, Faculte des Sciences, Universite de Annaba, B.P. 12, 23000 Annaba-Algerie (Algeria); Greneche, J.M. [Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087, Universite du Maine, Faculte des Sciences, F-72085, Le Mans Cedex 9 (France)

    2006-08-10

    Nanostructured Fe-6 wt.%Mo powders were prepared by mechanical alloying in a high-energy planetary ball-mill. The structural changes and the kinetics of Mo dissolution were studied by using X-ray diffraction. The crystallite size reduction down to about 11 nm is accompanied by the introduction of internal strains up to 1.1% (root-mean square strain, rms). After 24 h of milling, a bcc Fe(Mo) solid solution is formed. The kinetics of Mo dissolution into the Fe matrix during the milling process can be described by two regimes characterized by small values of Avrami parameter which do not exceed unit.

  6. Folded MoS2 layers with reduced interlayer coupling

    OpenAIRE

    Castellanos-Gomez, Andres; van der Zant, Herre S. J.; Steele, Gary A.

    2013-01-01

    We study molybdenum disulfide (MoS2) structures generated by folding single- and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement of the photoluminescence emission yield. We additionally find that folded single-layer MoS2 structures show a contribution to photoluminescence spectra of both neutral and charged excitons, which is a characteristic feature of single-layer MoS2 that has not been observed in multilayer M...

  7. Synthesis of nanometre-thick MoO3 sheets

    Science.gov (United States)

    Kalantar-Zadeh, Kourosh; Tang, Jianshi; Wang, Minsheng; Wang, Kang L.; Shailos, Alexandros; Galatsis, Kosmas; Kojima, Robert; Strong, Veronica; Lech, Andrew; Wlodarski, Wojtek; Kaner, Richard B.

    2010-03-01

    The formation of MoO3 sheets of nanoscale thickness is described. They are made from several fundamental sheets of orthorhombic α-MoO3, which can be processed in large quantities via a low cost synthesis route that combines thermal evaporation and mechanical exfoliation. These fundamental sheets consist of double-layers of linked distorted MoO6 octahedra. Atomic force microscopy (AFM) measurements show that the minimum resolvable thickness of these sheets is 1.4 nm which is equivalent to the thickness of two double-layers within one unit cell of the α-MoO3 crystal.

  8. -MoS2 Lateral Heterojunctions

    KAUST Repository

    Li, Ming-yang

    2018-02-28

    2D layered heterostructures have attracted intensive interests due to their unique optical, transport, and interfacial properties. The laterally stitched heterojunction based on dissimilar 2D transition metal dichalcogenides forms an intrinsic p–n junction without the necessity of applying an external voltage. However, no scalable processes are reported to construct the devices with such lateral heterostructures. Here, a scalable strategy, two-step and location-selective chemical vapor deposition, is reported to synthesize self-aligned WSe2–MoS2 monolayer lateral heterojunction arrays and demonstrates their light-emitting devices. The proposed fabrication process enables the growth of high-quality interfaces and the first successful observation of electroluminescence at the WSe2–MoS2 lateral heterojunction. The electroluminescence study has confirmed the type-I alignment at the interface rather than commonly believed type-II alignment. This self-aligned growth process paves the way for constructing various 2D lateral heterostructures in a scalable manner, practically important for integrated 2D circuit applications.

  9. Electron-induced excitation of 93Mo

    Science.gov (United States)

    Chiara, C. J.; Carroll, J. J.; Marsh, J. C.; Matters, D. A.; Lane, G. J.; Hartley, D. J.; Polasik, M.; Rzadkiewicz, J.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Seweryniak, D.; Zhu, S.

    2016-09-01

    The inverse of the internal-conversion process, whereby a free electron is captured into an atomic orbital and subsequently excites the nucleus to a higher-lying state via a virtual energy exchange, was predicted to exist 40 years ago but has yet to be demonstrated experimentally. To search for this mode of nuclear excitation by electron capture, we performed an experiment at the ATLAS facility at Argonne National Laboratory. The t1/2 = 6.85-h, 21/2+ state of 93Mo was populated in the 7Li(90Zr, p 3 n) reaction. The excitation mechanism was predicted to induce depopulation of this isomer as the fast-moving 93mMo recoils slowed in the target material, emitting a characteristic sequence of γ rays in the process. Results of the search for these signature γ rays using Digital Gammasphere will be presented. This material is based upon work supported by the US DOE, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. This research used resources of ANL's ATLAS facility, which is a DOE Office of Science User Facility.

  10. Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.

    Science.gov (United States)

    Kajima, Yuka; Takaichi, Atsushi; Nakamoto, Takayuki; Kimura, Takahiro; Yogo, Yoshiaki; Ashida, Maki; Doi, Hisashi; Nomura, Naoyuki; Takahashi, Hidekazu; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-06-01

    We aimed to investigate the fatigue strength of Co-Cr-Mo clasps for removable partial dentures prepared by selective laser melting (SLM). The Co-Cr-Mo alloy specimens for tensile tests (dumbbell specimens) and fatigue tests (clasp specimens) were prepared by SLM with varying angles between the building and longitudinal directions (i.e., 0° (TL0, FL0), 45° (TL45, FL45), and 90° (TL90, FL90)). The clasp specimens were subjected to cyclic deformations of 0.25mm and 0.50mm for 10(6) cycles. The SLM specimens showed no obvious mechanical anisotropy in tensile tests and exhibited significantly higher yield strength and ultimate tensile strength than the cast specimens under all conditions. In contrast, a high degree of anisotropy in fatigue performance associated with the build orientation was found. For specimens under the 0.50mm deflection, FL90 exhibited significantly longer fatigue life (205,418 cycles) than the cast specimens (112,770 cycles). In contrast, the fatigue lives of FL0 (28,484 cycles) and FL45 (43,465 cycles) were significantly shorter. The surface roughnesses of FL0 and FL45 were considerably higher than those of the cast specimens, whereas there were no significant differences between FL90 and the cast specimens. Electron backscatter diffraction (EBSD) analysis indicated the grains of FL0 showed preferential close to orientation of the γ phase along the normal direction to the fracture surface. In contrast, the FL45 and FL90 grains showed no significant preferential orientation. Fatigue strength may therefore be affected by a number of factors, including surface roughness and crystal orientation. The SLM process is a promising candidate for preparing tough removable partial denture frameworks, as long as the appropriate build direction is adopted. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Effect of Prior Austenite Grain Size on the Morphology of Nano-Bainitic Steels

    Science.gov (United States)

    Singh, Kritika; Kumar, Avanish; Singh, Aparna

    2018-04-01

    The strength in nanostructured bainitic steels primarily arises from the fine platelets of bainitic ferrite embedded in carbon-enriched austenite. However, the toughness is dictated by the shape and volume fraction of the retained austenite. Therefore, the exact determination of processing-morphology relationships is necessary to design stronger and tougher bainite. In the current study, the morphology of bainitic ferrite in Fe-0.89C-1.59Si-1.65Mn-0.37Mo-1Co-0.56Al-0.19Cr (wt pct) bainitic steel has been investigated as a function of the prior austenite grain size (AGS). Specimens were austenitized at different temperatures ranging from 900 °C to 1150 °C followed by isothermal transformation at 300 °C. Detailed microstructural characterization has been carried out using scanning electron microscopy and X-ray diffraction. The results showed that the bainitic laths transformed in coarse austenite grains are finer resulting in higher hardness, whereas smaller austenite grains lead to the formation of thicker bainitic laths with a large fraction of blocky type retained austenite resulting in lower hardness.

  12. Grain size refinement in nanocrystalline Hitperm-type glass-coated microwires

    International Nuclear Information System (INIS)

    Talaat, A.; Val, J.J. del; Zhukova, V.; Ipatov, M.; Klein, P.; Varga, R.; González, J.; Churyukanova, M.; Zhukov, A.

    2016-01-01

    We present a new-Fe 38.5 Co 38.5 B 18 Mo 4 Cu 1 Hitperm glass-coated microwires obtained by Taylor-Ulitovsky technique with nanocrystalline structure consisting of about 23 nm of BCC α-FeCo and an amorphous precursors in as-prepared samples. Annealing resulted in a considerable decrease of such nano-grains down to (11 nm). Obtained results are discussed in terms of the stress diffusion of limited crystalline growth and the chemical composition. Rectangular hysteresis loops have been observed on all annealed samples that are necessary conditions to obtain fast domain wall propagation. An enhancement of the domain wall velocity as well as mobility after annealing has been obtained due to the structural relaxation of such grains with positive magnetostriction. These structure benefits found in the nanocrystalline Hitperm glass-coated microwires are promising for developing optimal magnetic properties. - Highlights: • Grains size refinement upon annealing. • Enhancement of the domain wall velocity as well as mobility after annealing. • Nanocrystalline structure in as-prepared microwires.

  13. Organic Wheat Farming Improves Grain Zinc Concentration

    Science.gov (United States)

    Helfenstein, Julian; Müller, Isabel; Grüter, Roman; Bhullar, Gurbir; Mandloi, Lokendra; Papritz, Andreas; Siegrist, Michael; Schulin, Rainer; Frossard, Emmanuel

    2016-01-01

    Zinc (Zn) nutrition is of key relevance in India, as a large fraction of the population suffers from Zn malnutrition and many soils contain little plant available Zn. In this study we compared organic and conventional wheat cropping systems with respect to DTPA (diethylene triamine pentaacetic acid)-extractable Zn as a proxy for plant available Zn, yield, and grain Zn concentration. We analyzed soil and wheat grain samples from 30 organic and 30 conventional farms in Madhya Pradesh (central India), and conducted farmer interviews to elucidate sociological and management variables. Total and DTPA-extractable soil Zn concentrations and grain yield (3400 kg ha-1) did not differ between the two farming systems, but with 32 and 28 mg kg-1 respectively, grain Zn concentrations were higher on organic than conventional farms (t = -2.2, p = 0.03). Furthermore, multiple linear regression analyses revealed that (a) total soil zinc and sulfur concentrations were the best predictors of DTPA-extractable soil Zn, (b) Olsen phosphate taken as a proxy for available soil phosphorus, exchangeable soil potassium, harvest date, training of farmers in nutrient management, and soil silt content were the best predictors of yield, and (c) yield, Olsen phosphate, grain nitrogen, farmyard manure availability, and the type of cropping system were the best predictors of grain Zn concentration. Results suggested that organic wheat contained more Zn despite same yield level due to higher nutrient efficiency. Higher nutrient efficiency was also seen in organic wheat for P, N and S. The study thus suggests that appropriate farm management can lead to competitive yield and improved Zn concentration in wheat grains on organic farms. PMID:27537548

  14. The HEALTHGRAIN definition of 'whole grain'.

    Science.gov (United States)

    van der Kamp, Jan Willem; Poutanen, Kaisa; Seal, Chris J; Richardson, David P

    2014-01-01

    Most cereal products, like white bread, pasta, and biscuits, are based on flour after removal of bran and germ, the two parts of grain kernels containing most of the dietary fibre and other bioactive components. In the past decade, consumers have been rediscovering whole grain-based products and the number of wholegrain products has increased rapidly. In most countries in Europe and worldwide, however, no legally endorsed definition of wholegrain flour and products exists. Current definitions are often incomplete, lacking descriptions of the included grains and the permitted flour manufacturing processes. The consortium of the HEALTHGRAIN EU project (FP6-514008, 2005-2010) identified the need for developing a definition of whole grain with the following scope: 1) more comprehensive than current definitions in most EU countries; 2) one definition for Europe - when possible equal to definitions outside Europe; 3) reflecting current industrial practices for production of flours and consumer products; 4) useful in the context of nutritional guidelines and for labelling purposes. The definition was developed in a range of discussion meetings and consultations and was launched in 2010 at the end of the HEALTHGRAIN project. The grains included are specified: a wide range of cereal grains from the Poaceae family, and the pseudo-cereals amaranth, buckwheat, quinoa, and wild rice. The definition also describes manufacturing processes allowed for producing wholegrain flours. This paper compares the HEALTHGRAIN definition with previous definitions, provides more comprehensive explanations than in the definition itself regarding the inclusion of specific grains, and sets out the permitted flour manufacturing processes.

  15. Organic Wheat Farming Improves Grain Zinc Concentration.

    Directory of Open Access Journals (Sweden)

    Julian Helfenstein

    Full Text Available Zinc (Zn nutrition is of key relevance in India, as a large fraction of the population suffers from Zn malnutrition and many soils contain little plant available Zn. In this study we compared organic and conventional wheat cropping systems with respect to DTPA (diethylene triamine pentaacetic acid-extractable Zn as a proxy for plant available Zn, yield, and grain Zn concentration. We analyzed soil and wheat grain samples from 30 organic and 30 conventional farms in Madhya Pradesh (central India, and conducted farmer interviews to elucidate sociological and management variables. Total and DTPA-extractable soil Zn concentrations and grain yield (3400 kg ha-1 did not differ between the two farming systems, but with 32 and 28 mg kg-1 respectively, grain Zn concentrations were higher on organic than conventional farms (t = -2.2, p = 0.03. Furthermore, multiple linear regression analyses revealed that (a total soil zinc and sulfur concentrations were the best predictors of DTPA-extractable soil Zn, (b Olsen phosphate taken as a proxy for available soil phosphorus, exchangeable soil potassium, harvest date, training of farmers in nutrient management, and soil silt content were the best predictors of yield, and (c yield, Olsen phosphate, grain nitrogen, farmyard manure availability, and the type of cropping system were the best predictors of grain Zn concentration. Results suggested that organic wheat contained more Zn despite same yield level due to higher nutrient efficiency. Higher nutrient efficiency was also seen in organic wheat for P, N and S. The study thus suggests that appropriate farm management can lead to competitive yield and improved Zn concentration in wheat grains on organic farms.

  16. Equal Channel Angular Pressing (ECAP) and Its Application to Grain Refinement of Al-Zn-Mg-Cu Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tekeli, Sueleyman; Gueral, Ahmet

    2011-12-10

    Microstructure of a metal can be considerably changed by severe plastic deformation techniques such as high pressure torsion, extrusion and equal-channel angular pressing (ECAP). Among these methods, ECAP is particularly attractive because it has a potential for introducing significant grain refinement and homogeneous microstructure into bulk materials. Typically, it reduces the grain size to the submicrometer level or even nanometer range and thus produces materials that are capable of exhibiting unusual mechanical properties. In the present study, a test unites for equal channel angular pressing was constructed and this system was used for Al-Zn-Mg-Cu alloy. After the optimization tests, it was seen that the most effective lubricant for the dies was MoS{sub 2}, the pressing pressure was around 25-35 ton and the pressing speed was 2 mm/s. By using these parameters, the Al-Zn-Mg-Cu alloy was successfully ECAPed up to 14 passes at 200 deg. C using route C. After ECAP tests, the specimens were characterized by transmission electron microscope (TEM), hardness and macrostructural investigations. It was seen that the plastic deformation in the ECAPed specimens occurred from edge to the centre like whirlpool. In addition, the deformation intensity increased with increasing pass number. The grain size of the specimens effectively also decreased with increasing pass number. That is, while the grain size of unECAPed specimen was 10 {mu}m, this value decreased to 300 nm after 14 passes. At the beginning, while there was a banding tendency in the grains toward deformation direction, homogeneous and equiaxed grains were formed with increasing pass number. This grain refinement was as a result of an interaction between shear strain and thermal recovery during ECAP processing. Hardness measurements showed that the hardness values increased up to 4 passes, decreased effectively at 6th pass, again increased at 8th pass and after this pass, the hardness again decreased due to

  17. Equal Channel Angular Pressing (ECAP) and Its Application to Grain Refinement of Al-Zn-Mg-Cu Alloy

    Science.gov (United States)

    Tekeli, Süleyman; Güral, Ahmet

    2011-12-01

    Microstructure of a metal can be considerably changed by severe plastic deformation techniques such as high pressure torsion, extrusion and equal-channel angular pressing (ECAP). Among these methods, ECAP is particularly attractive because it has a potential for introducing significant grain refinement and homogeneous microstructure into bulk materials. Typically, it reduces the grain size to the submicrometer level or even nanometer range and thus produces materials that are capable of exhibiting unusual mechanical properties. In the present study, a test unites for equal channel angular pressing was constructed and this system was used for Al-Zn-Mg-Cu alloy. After the optimization tests, it was seen that the most effective lubricant for the dies was MoS2, the pressing pressure was around 25-35 ton and the pressing speed was 2 mm/s. By using these parameters, the Al-Zn-Mg-Cu alloy was successfully ECAPed up to 14 passes at 200 °C using route C. After ECAP tests, the specimens were characterized by transmission electron microscope (TEM), hardness and macrostructural investigations. It was seen that the plastic deformation in the ECAPed specimens occurred from edge to the centre like whirlpool. In addition, the deformation intensity increased with increasing pass number. The grain size of the specimens effectively also decreased with increasing pass number. That is, while the grain size of unECAPed specimen was 10 μm, this value decreased to 300 nm after 14 passes. At the beginning, while there was a banding tendency in the grains toward deformation direction, homogeneous and equiaxed grains were formed with increasing pass number. This grain refinement was as a result of an interaction between shear strain and thermal recovery during ECAP processing. Hardness measurements showed that the hardness values increased up to 4 passes, decreased effectively at 6th pass, again increased at 8th pass and after this pass, the hardness again decreased due to dynamic

  18. Novel technique to control oxygen fugacity during high-pressure measurements of grain boundary conductivities of rocks.

    Science.gov (United States)

    Dai, Lidong; Li, Heping; Hu, Haiying; Shan, Shuangming

    2009-03-01

    This paper describes the development and application of a novel method for the measurement of grain boundary electrical conductivity of rock at high temperature and pressure. In this method, the metal electrodes, the corresponding metal shielding case, and the sleeves are altered in order to appropriately adjust and monitor the oxygen fugacity in a sample cavity in a high-pressure apparatus. As an example, a series of oxygen buffers including Fe(3)O(4) + Fe(2)O(3), Ni + NiO, Fe + Fe(3)O(4), Fe + FeO, and Mo + MoO(2) was selected and tested, and the oxygen fugacity was confirmed as adjusted during the process of electrical conductivity measurements. Application of this method provides a powerful means of restricting specific thermodynamic conditions at high temperature and pressure.

  19. Page 1 306 R Viswanathan 10,000 o CrMoV, MG (ductile) e CrMoV ...

    Indian Academy of Sciences (India)

    the International Organization for Standardization's [ISO's] Larson–Miller data) is used as the reference condition for calculating the tr. In reality, as the component softens, the applicable Larson–Miller curve is continuously changing in such a way. O CrMoV, heat MG (ductile). © CrMoV, heat FW (brittle). C 2-1/4 Cr-1Mo, heat ...

  20. The impact of highly concentrated Mo and Cu dietary supplements, fed as a bolus, on the efficacy of chelated versus inorganic Cu in cattle on a low-Cu diet.

    Science.gov (United States)

    Grace, N D; West, D M; Smith, S L; Knowles, S O

    2013-11-01

    To compare the efficacy of chelated versus inorganic forms of dietary Cu supplements, fed as a bolus, when challenged by a daily bolus of dietary Mo in cattle on a low-Cu diet. Forty non-lactating, Friesian dairy cows of adequate Cu status were assigned to four groups and fed a basal diet of baled silage containing 5.3 mg Cu and 0.4 mg Mo/kg DM. The experimental design was a factorial of two chemical forms of supplemental Cu and two levels of Mo intake, provided as pelleted grain supplements made from crushed barley/molasses plus Cu and Mo. The supplements contained 140 mg Cu/kg as Cu sulphate pentahydrate (CS), 140 mg Cu/kg as Cu glycinate (CG), CS plus 38 mg Mo/kg as sodium molybdate (CS+Mo), or CG plus 38 mg Mo/kg (CG+Mo). Commencing on Day 0, supplements were fed once daily (offered 1-1.2 kg/cow) and were completely consumed within 5-10 minutes, which constitutes a bolus type of administration. Liver samples were collected by biopsy at Days -24, 13, 41 or 47, and 69 for Cu determinations. The diets fed to the Cu+Mo groups were roughly equivalent to 25 mg Cu and 5.7 mg Mo/kg DM. Mean initial concentration of Cu in liver for all groups was 516 (SE 54) μmol Cu/kg fresh tissue. In cows supplemented with CS and CG, the final (Day 69) concentrations increased (p0.25). The rate of accumulation of Cu in liver following bolus Cu and Mo intake was highly variable but was not affected by initial concentration of Cu in liver (p>0.9) or by the form of Cu (p>0.6). Mean rates of accumulation of Cu in liver were 4.0 (SD 3.8) and 0.65 (SD 2.0) μmol Cu/kg fresh tissue/day for the Cu-only treatments and the Cu+Mo treatments, respectively. When fed together as a bolus, high Mo intake negated the effect of supplemental Cu but it did not reduce liver Cu stores. There was no difference in the reaction of dietary Mo with chelated Cu (as glycinate) versus inorganic Cu (as sulphate) dietary supplements.

  1. Hidroxyapatite Coating on CoCrMo Alloy Titanium Nitride Coated Using Biomimetic Method

    International Nuclear Information System (INIS)

    Charlena; Sukaryo, S.G.; Fajar, M.

    2016-01-01

    Bone implants is a way to cure broken bones which is being developed. The implants can be made of metals, ceramics and polymers. Metallic materials commonly used are titanium (Ti), stainless steel, and metal alloys. This study used Co-based alloys, i.e. CoCrMo coated with titanium nitride (TiN) which was then coated on hidroxyapatite (HAp). The HAp coating on the surface of CoCrMo alloy was done by biomimetic methods, first by soaking the metal alloys in simulated body fluid (SBF) solution for 18, 24, and 36 hours. The immersion in the SBF solution produced white coat on the surface of the metal alloy. The layers formed were analyzed by scanning electron microscope (SEM) and characterized by x-ray diffractometer (XRD). Based on the SEM results of 36 hours treatment, the morphology of apatite crystal formed fine grains. According to XRD result, there were HAp peaks at angles 2θ 31.86, 32.25, dan 39.48. However, there were also CaCO 3 peaks at angles 2θ 29.46, 36.04, and 46.79. It indicated the pure HAp is not yet formed. (paper)

  2. Hidroxyapatite Coating on CoCrMo Alloy Titanium Nitride Coated Using Biomimetic Method

    Science.gov (United States)

    Charlena; Sukaryo, S. G.; Fajar, M.

    2016-11-01

    Bone implants is a way to cure broken bones which is being developed. The implants can be made of metals, ceramics and polymers. Metallic materials commonly used are titanium (Ti), stainless steel, and metal alloys. This study used Co-based alloys, i.e. CoCrMo coated with titanium nitride (TiN) which was then coated on hidroxyapatite (HAp). The HAp coating on the surface of CoCrMo alloy was done by biomimetic methods, first by soaking the metal alloys in simulated body fluid (SBF) solution for 18, 24, and 36 hours. The immersion in the SBF solution produced white coat on the surface of the metal alloy. The layers formed were analyzed by scanning electron microscope (SEM) and characterized by x-ray diffractometer (XRD). Based on the SEM results of 36 hours treatment, the morphology of apatite crystal formed fine grains. According to XRD result, there were HAp peaks at angles 2θ 31.86, 32.25, dan 39.48. However, there were also CaCO3 peaks at angles 2θ 29.46, 36.04, and 46.79. It indicated the pure HAp is not yet formed.

  3. Submerged arc narrow gap welding of the steel DIN 20MnMoNi55

    International Nuclear Information System (INIS)

    Moraes, M.M.

    1987-01-01

    The methodology for submerged arc narrow gap welding for high thickness rolled steel DIN 20MnMoNi55 was developed, using din S3NiMo1 04 mm and 05 mm wires, and DIN 8B435 flux. For this purpose, submerged arc narrow gap welded joints with 50 mm and 120 mm thickness were made aiming the welding parameters optimization and the study of the influence of welding voltage, wire diameter and wire to groove face distance on the operational performance and on the welded joint quality, specially on the ISO-V impact toughness. These welded joints were checked by non-destructive mechanical and metallographic tests. Results were compared with those obtained by one 120 mm thickness submerged arc conventional gap welded joint, using the same base metal and consumables (05 mm wire). The analysis of the results shows that the increasing of the wire to groove face distance and the welding voltage increases the hardness and the ISO-V impact toughness of the weld metal. It shows that the reduction of the gap angle is the main cause for the obtained of a heat affected zone free from coarse grains, the reduction of the welding voltage, the increasing of the wire to groove face distance, and the grounding optimization also contribute for that. It was also concluded that the quality and the execution complexity level of a narrow gap welded joint are identical to a conventional gap welded joint. (author) [pt

  4. Microstructure of HFIR-irradiated 12-Cr 1 MoVW ferritic steel

    International Nuclear Information System (INIS)

    Vitek, J.M.; Klueh, R.L.

    1983-01-01

    As part of the fusion materials development program in the United States, a 12 Cr-1 MoVW ferritic steel was irradiated in the High Flux Isotope Reactor (HFIR) to a damage level of 36 dpa at 300, 400, 500, and 600 0 C. During irradiation in HFIR, a transmutation reaction of nickel results in the production of helium, to a level of 99 at. ppM in the present experiment. The microstructures were evaluated after irradiation and the results are presented. Cavities were found at all temperatures. Small cavities (3 to 9 nm) were observed after irradiation at 300, 500 and 600 0 C. At 500 and 600 0 C, the cavities were found preferentially at dislocations, lath boundaries, and prior austenite grain boundaries. After irradiation at 400 0 C, larger cavities (4 to 30 nm) were observed homogeneously distributed throughout the tempered martensite structure. The maximum swelling was 0.07% after irradiation at 400 0 C. Comparision of the results with other studies in which helium was not present at such high levels indicated helium enhances the swelling of 12 Cr-1 MoVW

  5. Effect of Mo on dynamic recrystallization and microstructure development of microalloyed steels

    Science.gov (United States)

    Schambron, Thomas; Dehghan-Manshadi, Ali; Chen, Liang; Gooch, Taliah; Killmore, Chris; Pereloma, Elena

    2017-07-01

    The dynamic recrystallization (DRX) behaviour, mechanical properties and microstructure development of four low carbon, Nb-Ti-containing micro-alloyed steels with Mo contents from 0 to 0.27 wt% were studied. Plane strain compression tests were performed in a Gleeble 3500 thermomechanical simulator. The effects of composition, deformation temperature and strain rate on the DRX parameters and resultant microstructures were examined. The volume fraction of recrystallised grains was estimated from micrographs and a DRX model. The stress-strain curves showed the typical signs of DRX over a wide range of deformation conditions. Dynamic recovery was only observed for higher strain rates (5 s-1) and/or lower deformation temperatures (below 1000 °C). It was shown that Mo increases the hot strength by around 100 MPa per weight percent. In addition, it has an effect on retarding recrystallization in microalloyed steels by increasing the activation energy for DRX by 320 kJ/molK per weight percent. This was attributed to solute drag and the interaction with other microalloying elements.

  6. Recovery Efficiency of Enriched 100MoO3 Irradiated by Accelerator Neutrons

    Science.gov (United States)

    Kawabata, Masako; Motoishi, Shoji; Saeki, Hideya; Hashimoto, Kazuyuki; Nagai, Yasuki

    2017-05-01

    A 99% recovery of an enriched 100MoO3 sample weighing over 100 g was achieved for the first time after repeated separation procedures (milkings) by using a newly developed thermochromatography apparatus. Details of the distribution of 100MoO3 deposited within the apparatus were investigated after the milkings, and then the 100MoO3 was recovered. The apparatus has also shown the ability to separate high-quality 99mTc from 99MoO3 with a high efficiency of over 90% under repeated milking processes. This result is a significant development towards the stable and economical production of 99Mo by the 100Mo(n,2n)99Mo reaction. The method can be applied to other 99Mo production technologies such as the 98Mo(n,γ)99Mo and 100Mo(γ,n)99Mo reactions, which use large quantities of MoO3.

  7. The tribological difference between biomedical steels and CoCrMo-alloys.

    Science.gov (United States)

    Fischer, Alfons; Weiss, Sabine; Wimmer, Markus A

    2012-05-01

    In orthopedic surgery, different self-mating metal couples are used for sliding wear applications. Despite the fact that in mechanical engineering, self-mating austenitic alloys often lead to adhesion and seizure in biomedical engineering, the different grades of Co-base alloys show good clinical results, e.g., as hip joints. The reason stems from the fact that they generate a so-called tribomaterial during articulation, which consists of a mixture of nanometer small metallic grains and organic substances from the interfacial medium, which act as a boundary lubricant. Even though stainless steel also generate such a tribomaterial, they were ruled out from the beginning already in the 1950s as "inappropriate". On the basis of materials with a clinical track record, this contribution shows that the cyclic creep characteristics within the shear zone underneath the tribomaterial are another important criterion for a sufficient wear behavior. By means of sliding wear and torsional fatigue tests followed by electron microscopy, it is shown that austenitic materials generate wear particles of either nano- or of microsize. The latter are produced by crack initiation and propagation within the shear fatigue zone which is related to the formation of subsurface dislocation cells and, therefore, by the fact that an Ni-containing CrNiMo solid solution allows for wavy-slip. In contrast to this, an Ni-free CrMnMo solid solution with further additions of C and N only shows planar slip. This leads to the formation of nanosize wear particles and distinctly improves the wear behavior. Still, the latter does not fully achieve that of CoCrMo, which also shows a solely planar-slip behavior. This explains why for metallurgical reasons the Ni-containing 316L-type of steels had to fail in such boundary lubricated sliding wear tribosystems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Empirical insights into multi-grain averaging effects from ‘pseudo’ single-grain OSL measurements

    International Nuclear Information System (INIS)

    Arnold, L.J.; Demuro, M.; Ruiz, M. Navazo

    2012-01-01

    In this study we assess the signatures of multi-grain averaging effects for a series of sedimentary samples taken from the archaeological site of Hotel California, Atapuerca, Spain. We focus on the special case of equivalent dose (D e ) measurements made on single-grain discs that contain more than one quartz grain in each of the individual grain-hole positions with the aims of (i) providing insight into the nature and extent of averaging effects in very small multi-grain aliquots of sedimentary quartz, and (ii) assessing the suitability of ‘pseudo’ single-grain D e measurements for this particular dating application. Pseudo single-grain OSL measurements made on standard discs loaded with 90–100 μm grains (equivalent to ∼30 grains per hole) yield significantly different D e distribution characteristics and finite mixture model (FMM) burial dose estimates compared with single-grain OSL measurements. Grains with aberrant luminescence behaviours, which are routinely rejected during single-grain analysis, exert strong averaging effects on the pseudo single-grain and multi-grain aliquot D e distributions. Grain-hole averaging effects arising from pseudo single-grain measurements also give rise to ‘phantom’ dose components and are apt to provide bias assessments of quartz signal characteristics and grain type classifications. Though this is a site-specific study, it serves as a cautionary note for interpretations of other pseudo single-grain OSL and D e datasets – particularly those obtained from measurements of discs containing several tens of grains per hole and those derived from complex depositional environments. The use of custom single-grain discs drilled with smaller sized grain holes is recommended as a means of limiting grain-hole averaging effects when dealing with very fine (<180 μm) sediments.

  9. Microstructure and Hot Oxidation Resistance of SiMo Ductile Cast Irons Containing Si-Mo-Al

    Science.gov (United States)

    Ibrahim, Mervat M.; Nofal, Adel; Mourad, M. M.

    2017-04-01

    SiMo ductile cast irons are used as high-temperature materials in automotive components, because they are microstructurally stable at high operating temperatures. The effect of different amounts of Si and Mo as well as the addition of 3 wt pct Al on the microstructure, high-temperature oxidation, and mechanical properties of SiMo ductile cast iron was studied. Dilatometric measurements of SiMo ductile iron exhibited obvious differences in the transformation temperature A 1 due to presence of Al and the increase of Si. The microstructure of the SiMo alloys without Al addition showed outstanding nodularity and uniform nodule distribution. However, by adding 3 wt pct Al to low Si-SiMo ductile iron, some compacted graphite was observed. The results of oxidation experiments indicated that high Si-SiMo ductile iron containing 4 and 4.9 wt pct Si had superior resistance to lower Si-SiMo and SiMo ductile iron containing 3 wt pct Al. The results showed also that with increasing Si up to 4.9 wt pct or by replacing a part of Si with 3 wt pct Al, tensile strength increased while elongation and impact toughness decreased.

  10. The fracture toughness and DBTT of MoB particle-reinforced MoSi2 composites

    International Nuclear Information System (INIS)

    Xiong Zhi; Wang Gang; Jiang Wan

    2005-01-01

    The room temperature fracture toughness and the high temperature DBTT of MoB particle-reinforced MoSi 2 composites were investigated using Vickers indentation technique and MSP testing method, respectively. Modified small punch (MSP) test is a method for evaluation of mechanical properties using very small specimens, and it's appropriate for the determination of strength and DBTT. It was found that the approximate fracture toughness of the composite is 1.3 times that of monolithic MoSi 2 , and its DBTT is 100 C higher than that of monolithic MoSi 2 materials. Cracks deflection is a probable mechanism responsible for this behavior. (orig.)

  11. Magnetoresistance in Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions.

    Science.gov (United States)

    Zhang, Han; Ye, Meng; Wang, Yangyang; Quhe, Ruge; Pan, Yuanyuan; Guo, Ying; Song, Zhigang; Yang, Jinbo; Guo, Wanlin; Lu, Jing

    2016-06-28

    Semiconducting single-layer (SL) and few-layer MoS2 have a flat surface, free of dangling bonds. Using density functional theory coupled with non-equilibrium Green's function method, we investigate the spin-polarized transport properties of Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions with MoS2 layer numbers of N = 1, 3, and 5. Well-defined interfaces are formed between MoS2 and metal electrodes. The junctions with a SL MoS2 spacer are almost metallic owing to the strong coupling between MoS2 and the ferromagnets, while those are tunneling with a few layer MoS2 spacer. Both large magnetoresistance and tunneling magnetoresistance are found when fcc or hcp Co is used as an electrode. Therefore, flat single- and few-layer MoS2 can serve as an effective nonmagnetic spacer in a magnetoresistance or tunneling magnetoresistance device with a well-defined interface.

  12. Influence of synthesis conditions on microstructure and phase transformations of annealed Sr2FeMoO6−x nanopowders formed by the citrate–gel method

    Directory of Open Access Journals (Sweden)

    Marta Yarmolich

    2016-08-01

    Full Text Available The sequence of phase transformations during Sr2FeMoO6−x crystallization by the citrate–gel method was studied for powders synthesized with initial reagent solutions with pH values of 4, 6 and 9. Scanning electron microscopy revealed that the as-produced and annealed powders had the largest Sr2FeMoO6−x agglomerates with diameters in the range of 0.7–1.2 µm. The average grain size of the powders in the dispersion grows from 250 to 550 nm with increasing pH value. The X-ray diffraction analysis of the powders annealed at different temperatures between 770 and 1270 K showed that the composition of the initially formed Sr2FeMoO6−x changes and the molybdenum content increases with further heating. This leads to a change in the Sr2FeMoO6−x crystal lattice parameters and a contraction of the cell volume. An optimized synthesis procedure based on an initial solution of pH 4 allowed a single-phase Sr2FeMoO6−x compound to be obtained with a grain size in the range of 50–120 nm and a superstructural ordering of iron and molybdenum cations of 88%.

  13. Performance of organic grain legumes in Tuscany

    Directory of Open Access Journals (Sweden)

    Valentina Moschini

    2014-03-01

    Full Text Available In 2005-2007 growing season, few varieties of field bean, high protein pea and white lupin were compared in an organic farm of Central Italy (Mugello area, Tuscany, to evaluate their agronomic performance in terms of grain yield, nutritional quality and competitive ability against weeds. The experiment was performed under rain-fed conditions. Furthermore, grain legumes features were compared between two different sowing seasons (autumnal vs late-winter for two years, in order to get information on the best time of sowing of these species, and the stability of yields of different genotypes in those climatic and soil conditions. These legumes could be an alternative protein source to external soybean, a high-risk alimentary source of genetically modified organisms, in the organic livestock sector. The main findings indicate that higher yields in grain and crude protein were obtained with the pea species and in particular with cultivars Hardy (4.0 t/ha grain yield; 626 kg/ha crude protein yield and Classic (3.1 t/ha grain yield; 557 kg/ha crude protein yield; followed by field bean cv. Chiaro di Torre Lama (2.9 t/ha grain yield; 624 kg/ha crude protein yield and cv. Vesuvio (2.5 t/ha grain yield; 549 kg/ha crude protein yield. Furthermore the field bean is interesting for the stability of yield in both years despite climatic conditions rather different. The white lupin has showed the lower yield but the best values of grain quality, with higher values in lupin Multitalia for dry matter, crude protein and ether extract and in lupin Luxe also for crude fibre, respect to the other legumes analysed. Among lupin varieties, lupin Multitalia showed the best yield results for the pedo-climatic conditions of Mugello area (0.9 t/ha lupin Multitalia; 0.2 t/ha lupin Luxe. The total yield of organic grain legumes, in the experimental site, is resulted higher with an autumnal seeding respect to the late-winter seeding (2.8 t/ha vs 1.9 t/ha.

  14. 7 CFR 800.61 - Prohibited grain handling practices.

    Science.gov (United States)

    2010-01-01

    ... such blending will result in grain being designated as Mixed grain in accordance with subpart E of the... processed into a product(s) by the purchaser and not resold into the grain market. (3) Products or... include additional requirements for grain that is officially inspected and weighed. (3) Marketing dockage...

  15. Effect of stress-induced grain growth during room temperature ...

    Indian Academy of Sciences (India)

    The TEM observations reveal that stress-induced grain growth during tensile deformation is significantly suppressed for the nc Ni–Co alloys rich in Co in sharp contrast to those poor in Co. We believe that sufficient solutes could effectively pin grain boundaries making grain boundary motions (e.g. grain boundary migration ...

  16. Identification of putative candidate gene markers for grain zinc ...

    African Journals Online (AJOL)

    Gande

    2014-01-29

    Jan 29, 2014 ... 659. Table 1. Genes used for designing the primer. Name. Chromosome Location. Reference. OsYSL2. 2. High grain zn content. Chandel, 2011. OsNAAT1. 2. High grain zn content. Chandel, 2011. OsNAC. 3. High grain zn content. Chandel, 2011. OsZIP1. 3. High grain zn content. Chandel, 2011. OsZIP3. 4.

  17. Grain refinement of AZ31 magnesium alloy by electromagnetic ...

    Indian Academy of Sciences (India)

    ... effect on the grain size of AZ31 magnesium alloy under the effect of Al4C3 grain refiner. Electromagnetic stirring can `activate' the Al4C3 particles, resulting in more heterogeneous nucleation sites for the primary -Mg grains. But, longer holding time can `deactivate' the Al4C3 particles and poison the grain refining effect.

  18. Grain Boundaries From Theory to Engineering

    CERN Document Server

    Priester, Louisette

    2013-01-01

    Grain boundaries are a main feature of crystalline materials. They play a key role in determining the properties of materials, especially when grain size decreases and even more so with the current improvements of  processing tools and methods that allow us to control various elements in a polycrystal. This book presents the theoretical basis of the study of  grain boundaries and aims to open up new lines of research in this area. The treatment is light on mathematical approaches while emphasizing practical examples; the issues they raise are discussed with reference to theories. The general approach of the book has two main goals: to lead the reader from the concept of ‘ideal’ to ‘real’ grain boundaries; to depart from established knowledge and address the opportunities emerging through "grain boundary engineering",  the control of morphological and crystallographic features that affect material properties. The book is divided in three parts:  I ‘From interganular order to disorder’ deals wit...

  19. Advantageous grain boundaries in iron pnictide superconductors.

    Science.gov (United States)

    Katase, Takayoshi; Ishimaru, Yoshihiro; Tsukamoto, Akira; Hiramatsu, Hidenori; Kamiya, Toshio; Tanabe, Keiichi; Hosono, Hideo

    2011-08-02

    High critical temperature superconductors have zero power consumption and could be used to produce ideal electric power lines. The principal obstacle in fabricating superconducting wires and tapes is grain boundaries-the misalignment of crystalline orientations at grain boundaries, which is unavoidable for polycrystals, largely deteriorates critical current density. Here we report that high critical temperature iron pnictide superconductors have advantages over cuprates with respect to these grain boundary issues. The transport properties through well-defined bicrystal grain boundary junctions with various misorientation angles (θ(GB)) were systematically investigated for cobalt-doped BaFe(2)As(2) (BaFe(2)As(2):Co) epitaxial films fabricated on bicrystal substrates. The critical current density through bicrystal grain boundary (J(c)(BGB)) remained high (>1 MA cm(-2)) and nearly constant up to a critical angle θ(c) of ∼9°, which is substantially larger than the θ(c) of ∼5° for YBa(2)Cu(3)O(7-δ). Even at θ(GB)>θ(c), the decay of J(c)(BGB) was much slower than that of YBa(2)Cu(3)O(7-δ).

  20. Radiation disinfestation of grains and cocoa beans

    International Nuclear Information System (INIS)

    Appiah, V.

    1990-01-01

    A series of experiments has been performed by Ghanaian scientists from 1977 to 1987 to evaluate the seriousness of infestation and to establish effective doses for radiation disinfestation against insects and fungi which cause deterioration in grains and cocoa beans. Supporting investigations have been done on the effect of radiation disinfestation on some quality parameters and wholesomeness of grains (with maize as the test grain) and cocoa beans. A minimum dose of 0.8 kGy was established for effective control of insects present in stored grains and cocoa beans. For the decontamination against fungi and yeasts, a combination of moist heat (85% RH) applied to 60 deg. C for 30 min followed by a dose of 4 kGy was effective for maize and moist heat (85% RH) applied 80 deg. C and a dose of 4 kGy was recommended for cocoa beans. No significant difference was found between the organoleptic qualities of the products from maize and cocoa that had been treated with moist heat and radiation and the untreated samples. The cooling (solidifying) curves of cocoa butter prepared from untreated and treated cocoa beans were very similar. Irradiated cocoa beans were found to be wholesome. The prospects of radiation disinfestation of grains and cocoa beans have also been discussed. (author). 27 refs, 4 tabs

  1. Chemistry and infrared spectroscopy of interstellar grains

    International Nuclear Information System (INIS)

    Hagen, W.

    1982-01-01

    This thesis focuses on three aspects of interstellar grains: the photochemistry of the grain mantles, their infrared spectroscopy and the surface chemistry that takes place during mantle accretion. It provides a combination of pure and applied chemistry and spectroscopy. The experiments described in this thesis have been carried out with low temperature (10 K) solid molecular mixtures representing the mantles of interstellar grains. The samples have been prepared by slowly condensing gaseous mixtures of simple molecules (e.g. CO, H 2 O, NH 3 , CH 4 ) on a cold substrate (mirror or window) cooled by a cryogenic refrigerator mounted in a high vacuum chamber. Fourier transform infrared spectroscopy has been used to study the sample. A laboratory study of the photochemistry in interstellar grain mantles is described. It shows that irradiation of solid binary mixtures of CO with H 2 O, NH 3 or CH 4 with 1600 A vacuum ultraviolet light, which is representative of the interstellar ultraviolet field, gives rise to the formation of a number of large molecules as well as radicals. Moreover, a theoretical study is given of the chemical composition of grain mantles accreted in dense clouds. (Auth.)

  2. Design of Grain Refiners for Aluminium Alloys

    Science.gov (United States)

    Tronche, A.; Greer, A. L.

    The efficiency of a grain refiner can be quantified as the number of grains per nucleant particle in the solidified product. Even for effective refiners in aluminium, such as Al-5Ti-1B, it is known from experiments that efficiencies are very low, at best 10-3 to 102. It is of interest to explore the reasons for such low values, and to assess the prospects for increased efficiency though design of refiners. Recently it has been shown [1] that a simple recalescence-based model can make quantitative predictions of grain size as a function of refiner addition level, cooling rate and solute content. In the model, the initiation of grains is limited by the free growth from nucleant particles, the size distribution of which is very important. The present work uses this model as the basis for discussing the effect of particle size distribution on grain refiner performance. Larger particles (of TiB2 in the case of present interest) promote greater efficiency, as do narrower size distributions. It is shown that even if the size distribution could be exactly specified, compromises would have to be made to balance efficiency (defined as above) with other desirable characteristics of a refiner.

  3. Physical properties of monolithic U8 wt.%-Mo

    Science.gov (United States)

    Hengstler, R. M.; Beck, L.; Breitkreutz, H.; Jarousse, C.; Jungwirth, R.; Petry, W.; Schmid, W.; Schneider, J.; Wieschalla, N.

    2010-07-01

    As a possible high density fuel for research reactors, monolithic U8 wt.%-Mo ("U8Mo") was examined with regard to its structural, thermal and electric properties. X-ray diffraction by the Bragg-Brentano method was used to reveal the tetragonal lattice structure of rolled U8Mo. The specific heat capacity of cast U8Mo was determined by differential scanning calorimetry, its thermal diffusivity was measured by the laser flash method and its mass density by Archimedes' principle. From these results, the thermal conductivity of U8Mo in the temperature range from 40 °C to 250 °C was calculated; in the measured temperature range, it is in good accordance with literature data for UMo with 8 and 9 wt.% Mo, is higher than for 10 wt.% Mo and lower than for 5 wt.% Mo. The electric conductivity of rolled and cast U8Mo was measured by a four-wire method and the electron based part of the thermal conductivity calculated by the Wiedemann-Frantz law. Rolled and cast U8Mo was irradiated at about 150 °C with 80 MeV 127I ions to receive the same iodine ion density in the damage peak region as the fission product density in the fuel of a typical high flux reactor after the targeted nuclear burn-up. XRD analysis of irradiated U8Mo showed a change of the lattice parameters as well as the creation of UO 2 in the superficial sample regions; however, a phase change by irradiation was not observed. The determination of the electron based part of the thermal conductivity of the irradiated samples failed due to high measurement errors which are caused by the low thickness of the damage region in the ion irradiated samples.

  4. Mo-99 supply issues: Status report and lessons learned

    International Nuclear Information System (INIS)

    Ponsard, B.

    2010-01-01

    The worldwide supply of 99 Mo relies on a limited number of research reactors and processing facilities. Its production is essential for the nuclear medicine as 99m Tc, obtained from 99 Mo/ 99m Tc generators, is used in about 80% of the diagnostic nuclear imaging procedures. These applications represent yearly approximately 30 million examinations worldwide. The short half-life's of 99 Mo (66 hours) and its daughter 99m Tc (6 hours) require a regular supply of 99 Mo/ 99m Tc generators to hospitals or central radiopharmacies. Currently, there are only five nuclear reactors involved in the production of 99 Mo on industrial scale: NRU (Canada), HFR (Netherlands), BR2 (Belgium), OSIRIS (France) and SAFARI (South Africa). They irradiate highly enriched uranium targets for the production of about 95% of the available 99 Mo by four processing facilities: AECL/MDS NORDION (Canada), COVIDIEN (Netherlands), IRE (Belgium) and NTP (South Africa). However, these ageing reactors are subject to unscheduled shutdowns and longer maintenance periods making the 99 Mo supply chain vulnerable and unreliable. Several severe disruptions have been experienced since the fall 2005 due to the occurrence of problems at different stages of the supply chain: reactor outages, release of activity from processing facilities, recall of 99 Mo/ 99m Tc generators by the manufacturers, ... It is not expected that the situation will improve significantly in the near future. Therefore, several workshops have been organized in 2009 by the OECD Nuclear Energy Agency (NEA), the International Atomic Energy Agency (IAEA) and the Association of Imaging Producers and Equipment Suppliers (AIPES) to define measures that should be taken to secure the 99 Mo supply in the short, medium and long term. This paper summarizes the current status of the 99 Mo supply, discusses the ongoing plans for additional 99 Mo production capacity and outlines the issues for a reliable global supply chain. (author)

  5. Computerized pattern recognition used for grain counting in high resolution autoradiographs with low grain densities

    NARCIS (Netherlands)

    Schellart, N. A.; Zweijpfenning, R. C.; van Marle, J.; Huijsmans, D. P.

    1986-01-01

    Using a video-image system coupled to a minicomputer with commercial image handling software, autoradiographic grains displayed in dark-field are counted with a fast (ca. 3.5 min for 120,000 microns 2) and reliable (false scores less than 5%) grain-recognizing FORTRAN program executed in the users

  6. Statistical model for grain boundary and grain volume oxidation kinetics in UO2 spent fuel

    International Nuclear Information System (INIS)

    Stout, R.B.; Shaw, H.F.; Einziger, R.E.

    1989-09-01

    This paper addresses statistical characteristics for the simplest case of grain boundary/grain volume oxidation kinetics of UO 2 to U 3 O 7 for a fragment of a spent fuel pellet. It also presents a limited discussion of future extensions to this simple case to represent the more complex cases of oxidation kinetics in spent fuels. 17 refs., 1 fig

  7. Grain breakage under uniaxial compression, through 3D DEM modelling

    Directory of Open Access Journals (Sweden)

    Nader François

    2017-01-01

    Full Text Available A breakable grain model is presented, using the concept of particles assembly. Grains of polyhedral shapes are generated, formed by joining together tetrahedral subgrains using cohesive bonds. Single grain crushing simulations are performed for multiple values of the intra-granular cohesion to study the effect on the grain’s strength. The same effect of intra-granular cohesion is studied under oedometric compression on samples of around 800 grains, which allows the evaluation of grain breakage model on the macroscopic behaviour. Grain size distribution curves and grain breakage ratios are monitored throughout the simulations.

  8. Decreasing radioactive cesium in lodged buckwheat grain after harvest

    Directory of Open Access Journals (Sweden)

    Katashi Kubo

    2016-01-01

    Full Text Available This study assessed soil contamination with high radioactive cesium (R–Cs concentration in buckwheat grains by lodging, and assessed the possibility of R–Cs reduction in grain through post-harvest preparation. Analysis of buckwheat grain produced in farmers’ fields and reports from farmers indicated that grain from fields that had lodging showed higher R–Cs than grain from fields with no lodging. A field experiment demonstrated that R–Cs in grain after threshing and winnowing (TW was about six times higher in lodged plants than in nonlodged plants. In lodged plants, R–Cs in grain was decreased to about one-fourth by polishing, and was decreased to about one-seventh by ultrasonic cleaning, compared with R–Cs in grain after TW. These results demonstrate that R–Cs of buckwheat grain of lodged plants can be decreased by removing soil from the grain surface by polishing and winnowing.

  9. Evolution of grain boundary character distributions in alloy 825 tubes during high temperature annealing: Is grain boundary engineering achieved through recrystallization or grain growth?

    International Nuclear Information System (INIS)

    Bai, Qin; Zhao, Qing; Xia, Shuang; Wang, Baoshun; Zhou, Bangxin; Su, Cheng

    2017-01-01

    Grain boundary engineering (GBE) of nickel-based alloy 825 tubes was carried out with different cold drawing deformations by using a draw-bench on a factory production line and subsequent annealing at various temperatures. The microstructure evolution of alloy 825 during thermal-mechanical processing (TMP) was characterized by means of the electron backscatter diffraction (EBSD) technique to study the TMP effects on the grain boundary network and the evolution of grain boundary character distributions during high temperature annealing. The results showed that the proportion of ∑ 3 n coincidence site lattice (CSL) boundaries of alloy 825 tubes could be increased to > 75% by the TMP of 5% cold drawing and subsequent annealing at 1050 °C for 10 min. The microstructures of the partially recrystallized samples and the fully recrystallized samples suggested that the proportion of low ∑ CSL grain boundaries depended on the annealing time. The frequency of low ∑ CSL grain boundaries increases rapidly with increasing annealing time associating with the formation of large-size highly-twinned grains-cluster microstructure during recrystallization. However, upon further increasing annealing time, the frequency of low ∑ CSL grain boundaries decreased markedly during grain growth. So it is concluded that grain boundary engineering is achieved through recrystallization rather than grain growth. - Highlights: •The grain boundary engineering (GBE) is applicable to 825 tubes. •GBE is achieved through recrystallization rather than grain growth. •The low ∑ CSL grain boundaries in 825 tubes can be increased to > 75%.

  10. Final report : phase I investigation at the former CCC/USDA grain storage facility in Savannah, Missouri.

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, L. M.; Environmental Science Division

    2010-08-05

    From approximately 1949 until 1970, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility on federally owned property approximately 0.25 mi northwest of Savannah, Missouri (Figure 1.1). During this time, commercial grain fumigants containing carbon tetrachloride were commonly used by the CCC/USDA and the private grain storage industry to preserve grain in their facilities. In November 1998, carbon tetrachloride was detected in a private well (Morgan) roughly 50 ft south of the former CCC/USDA facility, as a result of state-wide screening of private wells near former CCC/USDA facilities, conducted in Missouri by the U.S. Environmental Protection Agency (EPA 1999). The 1998 and subsequent investigations by the EPA and the Missouri Department of Natural Resources (MoDNR) confirmed the presence of carbon tetrachloride in the Morgan well, as well as in a second well (on property currently owned and occupied by the Missouri Department of Transportation [MoDOT]), described as being approximately 400 ft east of the former CCC/USDA facility. The identified concentrations in these two wells were above the EPA maximum contaminant level (MCL) and the default target level (DTL) values of 5.0 {micro}g/L for carbon tetrachloride in water used for domestic purposes (EPA 1999; MoDNR 2000a,b, 2006). (The DTL is defined in Section 4.) Because the observed contamination in the Morgan and MoDOT wells might be linked to the past use of carbon tetrachloride-based fumigants at its former grain storage facility, the CCC/USDA is conducting an investigation to (1) characterize the source(s), extent, and factors controlling the subsurface distribution and movement of carbon tetrachloride at Savannah and (2) evaluate the potential risks to human health, public welfare, and the environment posed by the contamination. This work is being performed in accord with the Intergovernmental Agreement established between the Farm Service

  11. Microstructure and mechanical properties of friction stir welded 18Cr–2Mo ferritic stainless steel thick plate

    International Nuclear Information System (INIS)

    Han, Jian; Li, Huijun; Zhu, Zhixiong; Barbaro, Frank; Jiang, Laizhu; Xu, Haigang; Ma, Li

    2014-01-01

    Highlights: • We focus on friction stir welding of 18Cr–2Mo ferritic stainless steel thick plate. • We produce high-quality joints with special tool and optimised welding parameters. • We compare microstructure and mechanical properties of steel and joint. • Friction stir welding is a method that can maintain the properties of joint. - Abstract: In this study, microstructure and mechanical properties of a friction stir welded 18Cr–2Mo ferritic stainless steel thick plate were investigated. The 5.4 mm thick plates with excellent properties were welded at a constant rotational speed and a changeable welding speed using a composite tool featuring a chosen volume fraction of cubic boron nitride (cBN) in a W–Re matrix. The high-quality welds were successfully produced with optimised welding parameters, and studied by means of optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and standard hardness and impact toughness testing. The results show that microstructure and mechanical properties of the joints are affected greatly, which is mainly related to the remarkably fine-grained microstructure of equiaxed ferrite that is observed in the friction stir welded joint. Meanwhile, the ratios of low-angle grain boundary in the stir zone regions significantly increase, and the texture turns strong. Compared with the base material, mechanical properties of the joint are maintained in a comparatively high level

  12. Abnormal Grain Growth Suppression in Aluminum Alloys

    Science.gov (United States)

    Hales, Stephen J. (Inventor); Claytor, Harold Dale (Inventor); Alexa, Joel A. (Inventor)

    2015-01-01

    The present invention provides a process for suppressing abnormal grain growth in friction stir welded aluminum alloys by inserting an intermediate annealing treatment ("IAT") after the welding step on the article. The IAT may be followed by a solution heat treatment (SHT) on the article under effectively high solution heat treatment conditions. In at least some embodiments, a deformation step is conducted on the article under effective spin-forming deformation conditions or under effective superplastic deformation conditions. The invention further provides a welded article having suppressed abnormal grain growth, prepared by the process above. Preferably the article is characterized with greater than about 90% reduction in area fraction abnormal grain growth in any friction-stir-welded nugget.

  13. Large grain gallium arsenide thin films

    Science.gov (United States)

    Chu, S. S.; Chu, T. L.; Firouzi, H.; Han, Y. X.; Chen, W. J.; Wang, Q. H.

    Polycrystalline gallium arsenide films deposited on tungsten/graphite substrates have been used for the fabrication of thin film solar cells. Gallium arsenide films deposited on foreign substrates of 10 microns or less thickness exhibit, in most cases, pronounced shunting effects due to grain boundaries. MOS solar cells of 9 sq cm area with an AM1 efficiency of 8.5 percent and p(+)/n/n(+) homojunction solar cells of 1 sq cm area with an AM1 efficiency of 8.8 percent have been prepared. However, in order to further improve the conversion efficiency before the development of effective passivation techniques, gallium arsenide films with large and uniform grain structure are necessary. The large grain gallium arsenide films have been prepared by using (1) the arsine treatment of a thin layer of molten gallium on the substrate surface and (2) the recrystallized germanium films on tungsten/graphite as substrates.

  14. Wavelength selection of rolling grain ripples

    Science.gov (United States)

    Wesfreid, José Eduardo; Rousseaux, Germain; Baradel, Christian; Stegner, Alexandre

    2002-11-01

    A flat particle bed under an oscillatory viscous flow is generally unstable and leads to the formation of ripples. Using a cylindrical oscillating tank, we have studied in laboratory, at very high resolution, the wavelength selection, the morphology and the temporal evolution of theses ripples. Initially, the rolling of individual grains on the flat sand bed induces small rolling grain ripples. At this stage the wavelength selection depends on the grain diameter, the viscous boundary layer and the viscous length. In a second stage, the ripples follow a coarsening process which increase both the height and the wavelength of the patterns. For few cases, especially close to the onset of ripple formation, a logarithmic growth of the wavelength is observed. Then, if we wait long enough the system always evolves to a final vortex ripple state which is mainly controlled by the amplitude of the fluid excursion.

  15. Molecule production on interstellar oxide grains

    International Nuclear Information System (INIS)

    Duley, W.W.; Millar, T.J.; Williams, D.A.

    1978-01-01

    The microscopic nature of the surface of metal oxides is discussed, and a variety of surface defects are described. The chemical activity of these defects form the basis for the well-known catalytic properties of oxide materials. The types of defects likely to occur on interstellar oxide grains are investigated. Guided by extensive laboratory data on the catalytic properties of oxide materials, a list is given of reactions likely to occur on oxide grains in the interstellar medium. A specific model is proposed for the site which catalyses H 2 formation on interstellar grain surfaces. Sites of importance in the formation of the molecules are proposed to be of the (OH - ) type, as commonly observed on the surface of oxide materials. Under a plausible set of assumptions, molecular formation rates are estimated for low-density clouds, and it is suggested that the mechanisms described here will contribute significantly to interstellar chemistry. (author)

  16. Grain surface chemistry in protoplanetary disks

    International Nuclear Information System (INIS)

    Reboussin, Laura

    2015-01-01

    Planetary formation occurs in the protoplanetary disks of gas and dust. Although dust represents only 1% of the total disk mass, it plays a fundamental role in disk chemical evolution since it acts as a catalyst for the formation of molecules. Understanding this chemistry is therefore essential to determine the initial conditions from which planets form. During my thesis, I studied grain-surface chemistry and its impact on the chemical evolution of molecular cloud, initial condition for disk formation, and protoplanetary disk. Thanks to numerical simulations, using the gas-grain code Nautilus, I showed the importance of diffusion reactions and gas-grain interactions for the abundances of gas-phase species. Model results combined with observations also showed the effects of the physical structure (in temperature, density, AV) on the molecular distribution in disks. (author)

  17. An Optical Study of Ice Grain Boundaries

    Science.gov (United States)

    Thomson, Erik S.

    The equilibrium phase geometry and evolution of polycrystals underlies the nature of materials. In particular, grain boundaries dominate the total interfacial area within polycrystalline materials. Our experimental studies are motivated by the importance of the structure, evolution, and thermodynamic behavior of grain boundaries near bulk melting temperatures. Ice is singled out as a material of interest due to its geophysical importance and its advantageous optical properties. An experimental apparatus and light reflection technique is designed to measure grain boundary melting in ice bicrystals, in thermodynamic equilibrium The technique allows continuous monitoring of reflected light intensity from the grain boundary as the temperature and solutal composition are systematically varied. For each sample the individual crystal orientations are also measured. The type and concentration of impurity in the liquid is controlled and the temperature is continuously recorded and controlled over a range near the melting point. An optical model of the interface is developed in order to convert experimental reflection data into a physical measurement of the liquidity of the grain boundary. Solutions are found for reflection and transmission amplitude coefficients for waves propagating from an arbitrarily oriented uniaxial anisotropic material into an isotropic material. This general model is used to determine solutions for three layer, ice/water/ice, systems with crystals of arbitrary orientation, and is broadly applicable to layered materials. Experimental results show thicker grain boundary liquid layers than expected from classical colligative effects. A physically realistic model of intermolecular interactions succeeds in bounding the measurements. These measurements may have important implications for understanding a wide range of effects in polycrystalline materials. Likewise, the experimental techniques and optical theory may be applied to other systems of broad

  18. Quantum theory of multiscale coarse-graining

    Science.gov (United States)

    Han, Yining; Jin, Jaehyeok; Wagner, Jacob W.; Voth, Gregory A.

    2018-03-01

    Coarse-grained (CG) models serve as a powerful tool to simulate molecular systems at much longer temporal and spatial scales. Previously, CG models and methods have been built upon classical statistical mechanics. The present paper develops a theory and numerical methodology for coarse-graining in quantum statistical mechanics, by generalizing the multiscale coarse-graining (MS-CG) method to quantum Boltzmann statistics. A rigorous derivation of the sufficient thermodynamic consistency condition is first presented via imaginary time Feynman path integrals. It identifies the optimal choice of CG action functional and effective quantum CG (qCG) force field to generate a quantum MS-CG (qMS-CG) description of the equilibrium system that is consistent with the quantum fine-grained model projected onto the CG variables. A variational principle then provides a class of algorithms for optimally approximating the qMS-CG force fields. Specifically, a variational method based on force matching, which was also adopted in the classical MS-CG theory, is generalized to quantum Boltzmann statistics. The qMS-CG numerical algorithms and practical issues in implementing this variational minimization procedure are also discussed. Then, two numerical examples are presented to demonstrate the method. Finally, as an alternative strategy, a quasi-classical approximation for the thermal density matrix expressed in the CG variables is derived. This approach provides an interesting physical picture for coarse-graining in quantum Boltzmann statistical mechanics in which the consistency with the quantum particle delocalization is obviously manifest, and it opens up an avenue for using path integral centroid-based effective classical force fields in a coarse-graining methodology.

  19. Grain boundary disordering just before partial melting

    Science.gov (United States)

    Takei, Y.

    2017-12-01

    Recent experimental studies by using a rock analogue (organic polycrystals) have shown that significant enhancement of anelastic relaxation and steady-state creep in the partially molten aggregates starts from considerably below the solidus temperature in the absence of melt (Takei et al, 2014; Yamauchi & Takei, 2016, JGR). These results suggest that melt is not necessary to explain the seismic low velocity, high attenuation, and weak viscosity regions in the upper mantle. Indeed, Priestley & McKenzie (2006, 2013, EPSL) captured a steep reduction of seismic Vs just below the dry peridotite solidus, which was explained well by the empirical model of Yamauchi & Takei (2016). In spite of many geophysical implications (Takei, 2017, Ann. Rev. EPS, in press), however, underlying physics for the mechanical weakening just before partial melting remains unclear. The purpose of this study is to develop a physical model. Anelasticity and viscosity measured by Yamauchi & Takei (2016) are both rate-controlled by grain-boundary diffusion. Therefore, their observations suggest that the dynamic properties of grain boundary change just before partial melting. Significant disordering of grain boundary just before partial melting has been predicted theoretically in the area of material sciences (sometimes called `pre-melting'). I will summarize the thermodynamic models of grain boundary developed in these studies, and compare the predictions of these models to the experimental observations by Yamauchi & Takei (2016). Using these models, I will also clarify a relationship between grain-boundary disordering and grain-boundary wetting, and a different behavior between pure and binary systems in pre-melting. Acknowledgement: I thank R. Cooper for letting me know about the theoretical studies of pre-melting in binary eutectic system.

  20. Quantum theory of multiscale coarse-graining.

    Science.gov (United States)

    Han, Yining; Jin, Jaehyeok; Wagner, Jacob W; Voth, Gregory A

    2018-03-14

    Coarse-grained (CG) models serve as a powerful tool to simulate molecular systems at much longer temporal and spatial scales. Previously, CG models and methods have been built upon classical statistical mechanics. The present paper develops a theory and numerical methodology for coarse-graining in quantum statistical mechanics, by generalizing the multiscale coarse-graining (MS-CG) method to quantum Boltzmann statistics. A rigorous derivation of the sufficient thermodynamic consistency condition is first presented via imaginary time Feynman path integrals. It identifies the optimal choice of CG action functional and effective quantum CG (qCG) force field to generate a quantum MS-CG (qMS-CG) description of the equilibrium system that is consistent with the quantum fine-grained model projected onto the CG variables. A variational principle then provides a class of algorithms for optimally approximating the qMS-CG force fields. Specifically, a variational method based on force matching, which was also adopted in the classical MS-CG theory, is generalized to quantum Boltzmann statistics. The qMS-CG numerical algorithms and practical issues in implementing this variational minimization procedure are also discussed. Then, two numerical examples are presented to demonstrate the method. Finally, as an alternative strategy, a quasi-classical approximation for the thermal density matrix expressed in the CG variables is derived. This approach provides an interesting physical picture for coarse-graining in quantum Boltzmann statistical mechanics in which the consistency with the quantum particle delocalization is obviously manifest, and it opens up an avenue for using path integral centroid-based effective classical force fields in a coarse-graining methodology.

  1. Intercalation of Si between MoS2 layers

    NARCIS (Netherlands)

    van Bremen, Rik; Yao, Qirong; Banerjee, Soumya; Cakir, Deniz; Oncel, Nuri; Zandvliet, Harold J.W.

    2017-01-01

    We report a combined experimental and theoretical study of the growth of sub-monolayer amounts of silicon (Si) on molybdenum disulfide (MoS2). At room temperature and low deposition rates we have found compelling evidence that the deposited Si atoms intercalate between the MoS2 layers. Our evidence

  2. 77 FR 29875 - Establishment of Class E Airspace; Houston, MO

    Science.gov (United States)

    2012-05-21

    ...-0903; Airspace Docket No. 11-ACE-20] Establishment of Class E Airspace; Houston, MO AGENCY: Federal... at Houston, MO. Controlled airspace is necessary to accommodate new Area Navigation (RNAV) Standard Instrument Approach Procedures at Houston Memorial Airport. The FAA is taking this action to enhance the...

  3. Creep in directionally solidified NiAl-Mo eutectics

    Czech Academy of Sciences Publication Activity Database

    Dudová, Marie; Kuchařová, Květa; Barták, Tomáš; Bei, H.; George, E.P.; Somsen, Ch.; Dlouhý, Antonín

    2011-01-01

    Roč. 65, č. 8 (2011), s. 699-702 ISSN 1359-6462 R&D Projects: GA ČR GA202/09/2073 Institutional research plan: CEZ:AV0Z20410507 Keywords : high - temperature creep * NiAl - Mo eutectic * Mo fibres Subject RIV: JG - Metallurgy Impact factor: 2.699, year: 2011

  4. Mo-99 production by fission and future projections

    International Nuclear Information System (INIS)

    Carranza, E.C.; Novello, A.; Bronca, M.; Cestau, D.; Bavaro, R.; Centurion, R.; Bravo, C.; Bronca, P.; Gualda, E.; Fraguas, F.; Giomi, A.; Ivaldi, L.

    2012-01-01

    Description of the I-131 and Mo-99 production process: The process starts with the irradiation of uranium-aluminum mini plates in the RA-3, Argentinean Reactor No.3, Ezeiza Atomic Center. In a nuclear reactor there is a constant flow of neutrons and when a neutron with proper energy impacts on a nucleus of U-235, it is absorbed at the same time generate an unstable configuration nuclear. For this reason, the nucleus formed is fission, getting two different atoms. Approximately 6% of the fissions produce Mo-99 and 3% produce I-131; the percentage remaining corresponds to formation of atoms without interest for use in medicine. In conclusion, the objective of the process developed in the Fission Plant, is starting from uranium mini plates, separate the Mo-99 and I-131 generated, the remaining elements formed. - Evolution of Mo-99 Production in the last 10 years: The Fission Mo-99 Plant Production begins routine production of Mo-99 in 1985, using targets made of uranium enriched at 90% U-235. In the 1990s, global concern regarding the use of highly enriched uranium, due to non-proliferation issues, caused the interruption of supply of nuclear material (HEU enriched at 90% of U-235). Following this, Argentina developed target based on low-enriched uranium (less than 20% U-235), becoming in 2002 the first country in the world to produce Mo-99 with LEU targets. From 2002 to date, the activity produced of Mo-99 has been tripled annually (author)

  5. Mullite/Mo interfaces formed by Intrusion bonding

    Energy Technology Data Exchange (ETDEWEB)

    Bartolome, Jose F.; Diaz, Marcos; Moya, Jose S.; Saiz, Eduardo; Tomsia, Antoni P.

    2003-04-30

    The microstructure and strength of Mo/mullite interfaces formed by diffusion bonding at 1650 C has been analyzed. Interfacial metal-ceramic interlocking contributes to flexural strength of approx. 140 MPa as measured by 3 point bending. Saturation of mullite with MoO2 does not affect the interfacial strength.

  6. Structure, morphology and corrosion resistance of Ni–Mo+PTh ...

    Indian Academy of Sciences (India)

    Ni–Mo+PTh composite coatings were prepared from nickel–molybdenum galvanic bath with the addition of thiophene (Th) and HClO4 as result of two processes: induced Ni–Mo alloy deposition and PTh polymerization. A scanning electron microscope was used for surface morphology characterization of the coatings.

  7. setswana se ka tsenngwa kgotsa lomaganngwa jang mo thuta ...

    African Journals Online (AJOL)

    ... kgona sireletsa. le kutlo, dira go tsholwa mo labi motshwarakgamel sang. kgomong, se Go a se go ela gore e Go mosola a kamo, nna tlhoka a bonolo o Go monate. karolo e botlhokwa pono, mo rate, letlotlo go baithuting ya ruta tupelelo Go mme tlholego nna go motho fa leo itse karolo o gonne le e rata a mme leng tatso.

  8. LEUbased Fission Mo-99 Process with Reduced Solid Wastes

    International Nuclear Information System (INIS)

    Lee, Seungkon; Lee, Suseung; Jung, Sunghee; Hong, Soonbog; Jang, Kyungduk; Choi, Sang Mu; Lee, Jun Sig; Lim, Incheol

    2014-01-01

    99m Tc emits 140 keV of very low gamma-ray radiation energy, as low as conventional diagnostic X-ray, and has short half-life of 6.0058 hours. Therefore, as radioactive tracer, 99m Tc provides high quality diagnostic images but keeps total patient radiation exposure low. Depending on the tagging pharmaceuticals and procedures, 99m Tc can be applied for the diagnostics of various target organs and diseases: brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood and tumors. More than 95% of 99 Mo is produced through fission of 235 U worldwide because, 99m o generated from the fission (fission 99 Mo) exhibits very high specific activity (<100 Ci/g). Over 90% of fission 99 Mo producers have been used highly enriched uranium (HEU) targets so far. However, the IAEA recommends the use of low enriched uranium (LEU) to the 99 Mo producers for nonproliferation reason. These days, worldwide 99 Mo supply is not only insufficient but also unstable. Because, most of the main 99 Mo production reactors are about 50 years old and suffered from frequent and unscheduled shutdown. Planned weekly productivity of 2000 Ci fission 99 Mo, in a 6-day reference, will cover 100% domestic demand of Korea, as well as 20% of international market. It is expected to replace 4.3 million USD ($800/Ci) of 99 Mo import for domestic market while exporting 82.8 million USD for world market, annually

  9. Hydrocracking activity of NiMo-USY zeolite hydrotreating catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Egia, B.; Cambra, J.F.; Gueemez, B.; Arias, P.L. [Departamento de Ingeniera Quimica y del Medio Ambiente. Escuela de Ingenieros, Bilbao (Spain); Pawelec, B.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain)

    1997-07-01

    In previous works the hydrodesulfurization and hydrodenitrogenation activities of Ni, Mo and MoNi zeolite supported catalysts were studied, and a remarkable initial deactivation by cocking was detected. In the present work the hydrocracking activity of these catalysts in the sulfided state has been studied. 21 refs.

  10. Mo-Si-B-Based Coatings for Ceramic Base Substrates

    Science.gov (United States)

    Perepezko, John Harry (Inventor); Sakidja, Ridwan (Inventor); Ritt, Patrick (Inventor)

    2015-01-01

    Alumina-containing coatings based on molybdenum (Mo), silicon (Si), and boron (B) ("MoSiB coatings") that form protective, oxidation-resistant scales on ceramic substrate at high temperatures are provided. The protective scales comprise an aluminoborosilicate glass, and may additionally contain molybdenum. Two-stage deposition methods for forming the coatings are also provided.

  11. Highly flexible, conductive and transparent MoO3/Ag/MoO3 multilayer electrode for organic photovoltaic cells

    International Nuclear Information System (INIS)

    Abachi, T.; Cattin, L.; Louarn, G.; Lare, Y.; Bou, A.; Makha, M.; Torchio, P.

    2013-01-01

    MoO 3 /Ag/MoO 3 (MAM) multilayer structures were deposited by vacuum evaporation on polyethylene terephthalate (PET) substrate. We demonstrate that, as in the case of glass substrate, the sheet resistance of such structures depends significantly on the Ag film deposition rate. When it is deposited between 0.2 and 0.4 nm/s, an Ag thickness of 11 nm allows achieving sheet resistance of 13 Ω/sq and an averaged transmission of 74%. A study of the influence of the PET substrate on the optimum MoO 3 thicknesses was done. A good qualitative agreement between the theoretical calculations of the variation of the optical transmittance of the MoO 3 /Ag/MoO 3 structures is obtained. The optimum MAM structures MoO 3 (17.5 nm)/Ag (11 nm)/MoO 3 (35 nm) has a factor of merit F M = 4.21 10 −3 (Ω/sq) −1 . Proven by the scotch test the MAM structures exhibit a good adhesion to the PET substrates. The MAM structures were also submitted to bending tests. For outer bending, the samples exhibit no variation of their resistance value, while for inner bending there is a small increase of the resistance of the MAM structures. However this increasing is smaller than that exhibited by Indium Tin Oxide. When the PET/MAM structures are used as anode in organic photovoltaic cells, it is shown that the need to use thicker Ag films inside the multilayer and to cover the MAM with Au to obtain promising Current density vs Voltage characteristics is due to the heating of the PET substrate during the deposition process. - Highlights: • MoO 3 /Ag/MoO 3 structures deposited on polyethylene terephthalate substrate. • MoO 3 /Ag/MoO 3 structures deposited by vacuum evaporation. • The Ag deposition rate influences the properties of the structures. • The MoO 3 /Ag/MoO 3 optimum structure has a factor of merit F M = 4.21 10 −3 (Ω/sq) −1 . • The MoO 3 /Ag/MoO 3 structures exhibit a high flexibility

  12. MoRM and Future Memories

    DEFF Research Database (Denmark)

    Rehder, Mads Middelboe; Ostrowski, Kasper

    2017-01-01

    As part of a research project entitled ‘Creating Future Memories’ at Aarhus University a group of individuals blurring the boundaries between art, academics, and activism got together and participated in Counterplay 2016 at DOK1. Without any prior knowledge of the group-composition or possible aims...... for the experimental workshop we lunged into a process of devising both an interactive exhibition and an installation which explored the ‘big data’ citizens regularly produce in their everyday lives and how this data might be archived, packaged, and recycled - or even forgotten, primarily within social media. We...... wanted to explore what our daily routines connected to social media and sorting our data meant for the way we shape our memories, and therefore the traces of future memories. In this chapter we follow the trajectory of the exhibition entitled ‘MoRM’ (Museum of Random Memories)....

  13. ¿Cómo salir del liberalismo?

    Directory of Open Access Journals (Sweden)

    Lenin Flórez

    2001-01-01

    Full Text Available Alain Touraine ¿Cómo salir del Liberalismo? Piadós, Bacelona, 1999, 123 páginas. El libro parece circunscribirse al actual contexto político de Francia, que el autor considera como una coyuntura de salida del liberalismo. Su tema central gira alrededor de entender la democracia en este periodo y un proyecto político de más largo alcance. Sin embargo, sabemos que tiene serias investigaciones sobre la realidad latinoamericana, lo que nos indica que su temática rebasa el mundo europeo. Sin duda, el texto que reseñamos tiene un carácter crítico y sus planteamientos suscitan la controversia teórica.

  14. Chemical sensitivity of Mo gate Mos capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lombardi, R.M.; Aragon, R. [Laboratorio de Peliculas delgadas, Facultad de Ingenieria, Paseo Colon 850, 1063, Buenos Aires (Argentina)

    2006-07-01

    Mo gate Mos capacitors exhibit a negative shift of their C-V characteristic by up to 240 mV, at 125 C, in response to 1000 ppm hydrogen, in controlled nitrogen atmospheres. The experimental methods for obtaining capacitance and conductance, as a function of polarisation voltage, as well as the relevant equivalent circuits are reviewed. The single-state interface state density, at the semiconductor-dielectric interface, decreases from 2.66 x 10{sup 11} cm{sup -2} e-v{sup -1}, in pure nitrogen, to 2.5 x 10{sup 11} cm{sup -2} e-v{sup -1} in 1000 ppm hydrogen in nitrogen mixtures, at this temperature. (Author)

  15. Understanding Solidification Based Grain Refinement in Steels

    Science.gov (United States)

    2014-12-18

    Alumina Brick 42.2 52.6 1.4 2.3 0.2 0.3 Table 1 Composition of refractory materials The 99% alumina and 90% alumina samples showed no signs of reaction...dislocation can travel through a metal crystal before being blocked by a grain boundary. Since the dislocation is impeded sooner, the material cannot... thermomechanical methods for decreasing grain size. Steel castings are produced by making a mold using a pattern in the shape of the part. The pattern is removed

  16. Fine-grained concrete with organomineral additive

    Directory of Open Access Journals (Sweden)

    Solovyov Vitaly

    2016-01-01

    Full Text Available The article deals with the issues concerning the formation of the structure and properties of fine-grained concrete with organomineral additive produced through mechanochemical activation of thermal power plant fly ash together with superplasticizer. The additive is produced in a high-speed activator at the collision particles’ speed of about 80 m/s. The use of the additive in fine-grained concrete in the amounts of 0.5-1% increased the strength by 30-50% and reduced the size and volume of pores. The cement consumption in such concrete is close to the cement consumption in common concrete of equal resistance.

  17. Niobium-base grain refiner for aluminium

    International Nuclear Information System (INIS)

    Silva Pontes, P. da; Robert, M.H.; Cupini, N.L.

    1980-01-01

    A new chemical grain refiner for aluminium has been developed, using inoculation of a niobium-base compound. When a bath of molten aluminium is inoculated whith this refiner, an intermetallic aluminium-niobium compound is formed which acts as a powerful nucleant, producing extremely fine structure comparable to those obtained by means of the traditional grain refiner based on titanium and boron. It was found that the refinement of the structure depends upon the weight percentage of the new refiner inoculated as well as the time of holding the bath after inoculation and before pouring, but mainly on the inoculating temperature. (Author) [pt

  18. Optimization of UO{sub 2} Granule Characteristics for UO{sub 2}-Mo Pellet Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjoo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik; Oh, Jang Soo; Yang, Jae Ho; Koo, Yanghyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The in-reactor performance, integrity, safety and accident tolerance of the nuclear fuel can be significantly affected by the thermal conductivity of the UO{sub 2} fuel pellet. The improvement in the thermal conductivity of the UO{sub 2} fuel pellet can enhance the fuel performance in various ways. Typically, the FGR (Fission Gas Release) can be reduced by the application of a large-grain fuel pellet because the moving path of the fission gas to the grain boundary is much longer. In addition, the mobility of the fission gases is reduced by the lower temperature gradient in the UO{sub 2} fuel pellet. That is to say, the capacity of the fission gas retention of the fuel pellet can increase. In addition, the lower centerline temperature of the fuel pellet affects the accident tolerance for nuclear fuel as well as the enhancement of fuel safety and fuel pellet integrity under normal operation conditions. In addition, the nuclear reactor power can be uprated owing to the higher safety margin. Thus, many researches on enhancing the thermal conductivity of a nuclear fuel pellet for LWRs have been performed in various ways. From the viewpoint of the development of fuel pellet fabrication technology, an enhancement of the thermal conductivity of a pellet can be obtained by the addition of a higher thermal conductive material in the UO{sub 2} pellet. It is known that a UO{sub 2}-metal composite pellet is one of the most effective concepts. However, to maximize the effect of the metallic phase for thermal conductivity enhancement, a continuous channel of the metallic phase in the UO{sub 2} matrix must be formed. Additionally, if the fabrication process of a UO{sub 2}-metal composite pellet is compatible with a conventional sintering process, the developed technology will be favorable. To enhance the thermal conductivity of a UO{sub 2} pellet, there are the various methods for an appropriate arrangement of the high thermal conductive material in a UO{sub 2} matrix. In this

  19. Kinetic study of hydrogen evolution reaction on Ni30 Mo70, Co30Mo70, Co30Ni70 and Co10Ni20Mo70 alloy electrodes

    International Nuclear Information System (INIS)

    Dominguez-Crespo, M.A.; Plata-Torres, M.; Torres-Huerta, A.M.; Arce-Estrada, E.M.; Hallen-Lopez, J.M.

    2005-01-01

    The hydrogen evolution reaction on nanocrystalline Ni 30 Mo 70 , Co 30 Mo 70 , Co 30 Ni 70 , and Co 10 Ni 20 Mo 70 , metallic powders prepared by mechanical alloying was investigated with linear polarization and ac impedance methods, in 30 wt.% KOH aqueous solution at room temperature. The formation process and structural properties of these nanocrystalline materials were characterized by X-ray diffraction and transmission electron microscopy. Alloyed powders showed the presence of two phases: an fcc solid solution and intermetallic compounds of Ni, Co and Mo. Based on polarization and ac impedance measurements, an improved electrocatalytic activity for hydrogen evolution reaction was observed in mechanically alloyed Co 30 Ni 70 powders, which is slightly higher than milled metallic Ni powders

  20. A study of electron beam welding of Mo based TZM alloy

    International Nuclear Information System (INIS)

    Chakraborty, S.P.; Krishnamurthy, N.

    2013-12-01

    Mo based TZM alloy is one of the most promising refractory alloy having several unique high temperature properties suitable for structural applications in the new generation advanced nuclear reactors. However, this alloy easily picks up interstitial impurities such as N 2 , H 2 and C from air during welding due to its reactive nature. High melting point of TZM alloy also restricts use of conventional welding technique for welding. Hence, Electron beam welding (EBW) technique with its deep penetration power to produce narrow heat affected zones under high vacuum was employed to overcome the above welding constraints by conducting a systematic study using both processes of bead on plate and butt joint configuration. Uniform and defect free weld joints were produced. Weld joints were subjected to optical characterization, chemical homogeneity analysis and microhardness profile study across the width of welds. Improved grain structure with equiaxed grains was obtained in the weld zone as compared to fibrous base structure. Original chemical composition was retained in the weld zone. The detailed results are described in this report. (author)

  1. A Microstructure Evolution Model for Hot Rolling of a Mo-TRIP Steel

    Science.gov (United States)

    Liu, Dongsheng; Fazeli, F.; Militzer, M.; Poole, W. J.

    2007-04-01

    A comprehensive study of microstructure evolution for a Mo-TRIP (transformation-induced-plasticity) steel under hot strip rolling conditions has been conducted. This investigation includes austenite grain growth during reheating, deformation behavior, and static recrystallization kinetics of austenite as well as the effect of cooling rate and austenite conditioning on the continuous cooling transformation (CCT) behavior. The physically based Kocks Mecking model has been employed to describe the deformation behavior of austenite, while the Johnson Mehl Avrami Kolmogorov (JMAK) approach has been used to predict static recrystallization, and an empirical equation has been formulated for the recrystallized austenite grain size. Ferrite transformation start is described by a model considering early growth of corner nucleated ferrite. The fraction of ferrite transformed from austenite during continuous cooling is predicted by the semiempirical JMAK approach in combination with Scheil’s equation of additivity. The effect of carbon enrichment on ferrite transformation kinetics is explicitly included in the model. In addition, a phenomenological model for the bainite formation has been proposed. Martensite transformation start is described by an empirical equation taking into account carbon enrichment of remaining austenite. Finally, the entire hot strip rolling and controlled cooling process have been simulated by hot torsion tests, and the optimum coiling temperatures for the formation of TRIP microstructures have been determined.

  2. Evaluation of creep damage in a welded joint of modified 9Cr-1Mo steel

    Science.gov (United States)

    Li, Yongkui; Monma, Yoshio; Hongo, Hiromichi; Tabuchi, Masaaki

    2010-10-01

    This paper aims to evaluate the creep damage of modified 9Cr-1Mo steel under 600 °C operating conditions, using constitutive equations based on the continuum damage mechanics. The accumulation of voids over a long period is believed to contribute to the formation of Type IV cracking, which in turn leads eventually to the failure of weldment under conditions of higher temperatures and lower stresses. Specimens of base metal, a simulated fine-grained heat affected zone, and a thin (thick) welded joint were kept under stress from 80 to 160 MPa at 600 °C. During the creep tests of thick plate welded joint specimens, the application of stress was suspended several times, and the creep damage as indicated by the void distribution was examined quantitatively using a laser microscope. The combined effect of the equivalent creep strain and the stress triaxial factor was considered and introduced into the constitutive equations with the aid of a finite element method. The logarithms of m and 1/λ in the continuum damage mechanics equations were determined to have a linear correlation with the ratio of the applied stress to the yield stress for homogeneous materials. In this way, the damage distribution and evolution in the fine-grained heat affected zone were evaluated successfully.

  3. Whole grain intake: The Baltimore Longitudinal Study of Aging.

    Science.gov (United States)

    Maras, Janice E; Newby, P K; Bakun, Peter J; Ferrucci, Luigi; Tucker, Katherine L

    2009-02-01

    Our objective was to identify major dietary sources of whole grains and to describe the construction of a database of whole grain content of foods. Dietary information was collected with 7-d food records from men and women in the Baltimore Longitudinal Study of Aging, mean age 62.1 +/- 16.0 years, who participated in the dietary assessment portion of the study (n = 1516), and estimates of whole grain intake were obtained from a newly developed database. The Pyramid Servings database and 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII) recipe ingredients database were then used to calculate both servings and gram weights of whole grain intakes. Mean intakes of whole grains, refined grains, and total grains, as well as frequency of intake for major whole grain food groups and whole grain content for each group, were calculated. Top contributors of whole grains were ready-to-eat breakfast cereals (made with whole grain as well as bran), hot breakfast cereals (made with whole grain), multi-grain bread, and whole wheat bread. While more research is needed to better understand the benefits of whole grains, the development of research tools, including databases to accurately assess whole grain intake, is a critical step in completing such research.

  4. Rocking disc electro-deposition of copper films on Mo/MoSe{sub 2} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, Charles Y.; Frith, Paul E. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Zoppi, Guillaume; Forbes, Ian [Northumbria Photovoltaics Applications Centre, Northumbria University, NE1 8ST (United Kingdom); Rogers, Keith D. [Cranfield Health, Cranfield University, Shrivenham Campus, Swindon, SN6 8LA (United Kingdom); Lane, David W. [Department of Applied Science, Security and Resilience, Cranfield University, Shrivenham, Swindon, SN6 8LA (United Kingdom); Marken, Frank, E-mail: F.Marken@bath.ac.uk [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2011-08-31

    A novel electro-deposition method based on a rocking disc system with {pi}/3 amplitude and variable frequency is introduced. Uniform copper films were deposited from a 0.1 M CuSO{sub 4}/3.0 M NaOH/0.2 M sorbitol bath directly onto 12.1 cm{sup 2} Mo/MoSe{sub 2} substrates with X-ray diffraction showing a thickness variation of {+-}5% over this area. Investigation of the mass transport conditions suggests (i) uniform diffusion over the sample, (ii) a rate of mass transport proportional to the square root of the rocking rate, and (iii) turbulent conditions, which are able to dislodge gas bubbles during electro-deposition.

  5. Physical Activity of German Children and Adolescents 2003–2012: The MoMo-Study

    Directory of Open Access Journals (Sweden)

    Steffen C. E. Schmidt

    2017-11-01

    Full Text Available Organized and unorganized physical activity (PA hold an important role in the daily life of children and adolescents. Regular representative tracking of PA in different settings is important to evaluate social trends and implemented interventions. In this paper, representative PA data of German children and adolescents from the MoMo Baseline-Study (2004, n = 4528 are compared to those of Wave 1 (2010, n = 3994. Participants aged 4–17 were drawn out of 167 sample points in Germany and the data was weighted to ensure representativeness. PA was measured via questionnaire and was differentiated between organized (sports clubs and schools and unorganized (unorganized sports and playing outside. Organized PA in extracurricular activities and sports clubs increased by eight percent, while unorganized PA decreased by seven percent. In addition to sports clubs, schools became a more prevalent setting for participation in physical activity in Germany.

  6. Rhenium-doped MoS2 films

    Science.gov (United States)

    Hallam, Toby; Monaghan, Scott; Gity, Farzan; Ansari, Lida; Schmidt, Michael; Downing, Clive; Cullen, Conor P.; Nicolosi, Valeria; Hurley, Paul K.; Duesberg, Georg S.

    2017-11-01

    Tailoring the electrical properties of transition metal dichalcogenides by doping is one of the biggest challenges for the application of 2D materials in future electronic devices. Here, we report on a straightforward approach to the n-type doping of molybdenum disulfide (MoS2) films with rhenium (Re). High-Resolution Scanning Transmission Electron Microscopy and Energy-Dispersive X-ray spectroscopy are used to identify Re in interstitial and lattice sites of the MoS2 structure. Hall-effect measurements confirm the electron donating influence of Re in MoS2, while the nominally undoped films exhibit a net p-type doping. Density functional theory (DFT) modelling indicates that Re on Mo sites is the origin of the n-type doping, whereas S-vacancies have a p-type nature, providing an explanation for the p-type behaviour of nominally undoped MoS2 films.

  7. MoS2-supported gold nanoparticle for CO hydrogenation

    Science.gov (United States)

    Rawal, Takat B.; Le, Duy; Rahman, Talat S.

    2017-10-01

    Employing dispersion-corrected density functional theory, we examine the geometry, electronic structure, and reactivity of 13-atom Au nanoparticle supported on defect-laden single-layer MoS2. The planar structure of Au13 favored in isolated phase, transforms into the three-dimensional structure when supported on MoS2. We find that charge is transferred from MoS2 to Au13, and that the electron density is also distributed away from the Au13/MoS2 interfacial region—making Au sites away from the interface catalytically active. Owing to effect of the support, the Au d states become narrower, and the frontier states appear close to the Fermi level. Consequently, in contrast to the reactivity of Au13/TiO2 toward methanol decomposition, Au13/MoS2 offers excellent activity toward methanol synthesis, as demonstrated here, via CO hydrogenation.

  8. Charge density waves in nanocrystalline thin films of blue bronze K0.3MoO3

    International Nuclear Information System (INIS)

    Starešinić, D.; Dominko, D.; Salamon, K.; Biljaković, K.; Tomeljak, A.; Schäfer, H.; Huber, T.; Demsar, J.; Socol, G.; Ristoscu, C.; Mihailescu, I.N.; Siketić, Z.

    2012-01-01

    Thin granular films of charge density wave (CDW) system K 0.3 MoO 3 were prepared by pulsed laser deposition and investigated by various standard characterization methods such as GI-XRD, electric transport, TOF-ERDA, AFM and UV–visible spectroscopy. While all these methods indicate that the thin films consist of nanometer grains of K 0.3 MoO 3 , it is only the non-destructive femtosecond time-resolved spectroscopy (fsTRS) that demonstrates the charge density wave nature of the ground state and therefore proves directly the presence of K 0.3 MoO 3 . Furthermore, the comparison of the fsTRS data obtained in thin films and in single crystals shows the reduction of the charge density wave transition temperature and of the photoinduced signal strength in granular thin films with respect to single crystals, which is attributed to the granularity and crystal growth morphology. Our results establish fsTRS technique as the essential tool for the detection and characterization of complex ground states in nano-sized systems.

  9. MoSbTe for high-speed and high-thermal-stability phase-change memory applications

    Science.gov (United States)

    Liu, Wanliang; Wu, Liangcai; Li, Tao; Song, Zhitang; Shi, Jianjun; Zhang, Jing; Feng, Songlin

    2018-04-01

    Mo-doped Sb1.8Te materials and electrical devices were investigated for high-thermal-stability and high-speed phase-change memory applications. The crystallization temperature (t c = 185 °C) and 10-year data retention (t 10-year = 112 °C) were greatly enhanced compared with those of Ge2Sb2Te5 (t c = 150 °C, t 10-year = 85 °C) and pure Sb1.8Te (t c = 166 °C, t 10-year = 74 °C). X-ray diffraction and transmission electron microscopy results show that the Mo dopant suppresses crystallization, reducing the crystalline grain size. Mo2.0(Sb1.8Te)98.0-based devices were fabricated to evaluate the reversible phase transition properties. SET/RESET with a large operation window can be realized using a 10 ns pulse, which is considerably better than that required for Ge2Sb2Te5 (∼50 ns). Furthermore, ∼1 × 106 switching cycles were achieved.

  10. Synthesis and characterization of MoB2−x thin films grown by nonreactive DC magnetron sputtering

    International Nuclear Information System (INIS)

    Malinovskis, Paulius; Lewin, Erik; Jansson, Ulf; Palisaitis, Justinas; Persson, Per O. Å.

    2016-01-01

    DC magnetron sputtering was used to deposit molybdenum boride thin films for potential low-friction applications. The films exhibit a nanocomposite structure with ∼10 nm large MoB 2−x (x > 0.4) grains surrounded by a boron-rich tissue phase. The preferred formation of the metastable and substoichiometric hP3-MoB 2 structure (AlB 2 -type) is explained with kinetic constraints to form the thermodynamically stable hR18-MoB 2 phase with a very complex crystal structure. Nanoindentation revealed a relatively high hardness of (29 ± 2) GPa, which is higher than bulk samples. The high hardness can be explained by a hardening effect associated with the nanocomposite microstructure where the surrounding tissue phase restricts dislocation movement. A tribological study confirmed a significant formation of a tribofilm consisting of molybdenum oxide and boron oxide, however, without any lubricating effects at room temperature.

  11. A detailed study of the amorphisation reaction in NiMo alloys by diffraction and scattering methods

    International Nuclear Information System (INIS)

    Rose, P.

    1995-01-01

    X-ray and neutron diffraction and neutron small angle scattering (SAS) measurements have been made on NiMo specimens prepared by mechanical alloying (MA). We have extended our earlier studies and measured a new series of MA treated NiMo samples. Molybdenum scatters X-rays more strongly than nickel, but with neutrons, the reverse is the case. Analysis of the X-ray and neutron diffraction patterns together, therefore provides an accurate measurement of the consumption of both constituents in the reaction. The diffraction data on the new samples confirm that the consumption of the parent crystalline materials follows an exponential dependence with the time of MA treatment and also provides evidence of a ''delayed start'' to the reaction. This is consistent with an initial period of mixing of the constituents before the onset of (atomic) interdiffusion and amorphisation. The neutron SAS experiments have been made on Ni 47.7 Mo 52.3 MA treated specimens, which can be ''contrast-matched'' to reduce the scattering from the external surfaces of the powder grains. The new neutron SAS data confirm the presence of fractal surfaces between the alloy constituents, for samples in the early stages of the MA process. (orig.)

  12. Initiation of Stress Corrosion Cracking of 26Cr-1Mo Ferritic Stainless Steels in Hot Chloride Solution

    International Nuclear Information System (INIS)

    Kwon, H. S.; Hehemann, R. F.

    1987-01-01

    Elongation measurements of 26Cr-1Mo ferritic stainless steels undergoing stress corrosion in boiling LiCl solution allow the induction period to be distinguished from the propagation period of cracks by the deviation of elongation from the logarithmic creep law. Localised corrosion cells are activated exclusively at slip steps by loading and developed into corrosion trenches. No cracks have developed from the corrosion trenches until the induction period is exceeded. The induction period is regarded as a time for localised corrosion cells to achieve a critical degree of occlusion for crack initiation. The repassivation rate of exposed metal by creep or emergence of slip steps decreases as the load increases and is very sensitive to the microstructural changes that affect slip tep height. The greater susceptibility to stress corrosion cracking of either prestrained or grain coarsened 26Cr-1Mo alloy compared with that of mill annealed material results from a significant reduction of repassivation rate associated with the increased slip step height. The angular titanium carbonitrides particles dispersed in Ti-stabilized 26Cr-1Mo alloy have a detrimental effect on the resistance to stress corrosion cracking

  13. Final report of MoReMO 2011-2012. Modelling resilience for maintenance and outage

    Energy Technology Data Exchange (ETDEWEB)

    Gotcheva, N.; Macchi, L.; Oedewald, P. [Technical Research Centre of Finland (VTT), Espoo (Finland); Eitrheim, M.H.R. [Institute for Energy Technology (IFE) (Norway); Axelsson, C.; Reiman, T.; Pietikaeinen, E. [Ringhals AB (NPP), Vattenfall AB (Sweden)

    2013-04-15

    The project Modelling Resilience for Maintenance and Outage (MoReMO) represents a two-year joint effort by VTT Technical Research Centre of Finland, Institute for Energy Technology (IFE, Norway) and Vattenfall (Sweden) to develop and test new approaches for safety management. The overall goal of the project was to present concepts on how resilience can be operationalized and built in a safety critical and socio-technical context. Furthermore, the project also aimed at providing guidance for other organizations that strive to develop and improve their safety performance in a business driven industry. We have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. During 2011 and 2012 the MoReMO project team has collected data through field observations, interviews, workshops, and document analysis on the work practices and adjustments in maintenance and outage in Nordic NPPs. The project consisted of two sub-studies, one focused on identifying and assessing adjustments and supporting resilient work practices in maintenance activities, while the other focused on handling performance trade-offs in maintenance and outage, as follows: A. Adjustments in maintenance work in Nordic nuclear power plants (VTT and Vattenfall). B. Handling performance trade-offs - the support of adaptive capacities (IFE and Vattenfall). The historical perspective of maintenance and outage management (Chapter 1.1) was provided by Vattenfall. Together, the two sub-studies have provided valuable insights for understanding the rationale behind work practices and adjustments, their effects on resilience, promoting flexibility and balancing between flexibility and reliability. (Author)

  14. Sheet-like of Mo –Sm assembly containing [Mo (CN)8 ] and Sm ions ...

    Indian Academy of Sciences (India)

    Administrator

    ions as building blocks. SHU-LIN MA1,*, SHI REN1, YUE MA2 and DAI-ZHENG LIAO2,*. 1. Department of Application Chemistry, College of Science, Tianjin University of Commerce, ... based on large extended of 4d or 5d magnetic orbi- tals, [MV(CN)8]3– (M = Mo and W) are a kind of good precursors in magnetic materials.

  15. Final report of MoReMO 2011-2012. Modelling resilience for maintenance and outage

    International Nuclear Information System (INIS)

    Gotcheva, N.; Macchi, L.; Oedewald, P.; Eitrheim, M.H.R.; Axelsson, C.; Reiman, T.; Pietikaeinen, E.

    2013-04-01

    The project Modelling Resilience for Maintenance and Outage (MoReMO) represents a two-year joint effort by VTT Technical Research Centre of Finland, Institute for Energy Technology (IFE, Norway) and Vattenfall (Sweden) to develop and test new approaches for safety management. The overall goal of the project was to present concepts on how resilience can be operationalized and built in a safety critical and socio-technical context. Furthermore, the project also aimed at providing guidance for other organizations that strive to develop and improve their safety performance in a business driven industry. We have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. During 2011 and 2012 the MoReMO project team has collected data through field observations, interviews, workshops, and document analysis on the work practices and adjustments in maintenance and outage in Nordic NPPs. The project consisted of two sub-studies, one focused on identifying and assessing adjustments and supporting resilient work practices in maintenance activities, while the other focused on handling performance trade-offs in maintenance and outage, as follows: A. Adjustments in maintenance work in Nordic nuclear power plants (VTT and Vattenfall). B. Handling performance trade-offs - the support of adaptive capacities (IFE and Vattenfall). The historical perspective of maintenance and outage management (Chapter 1.1) was provided by Vattenfall. Together, the two sub-studies have provided valuable insights for understanding the rationale behind work practices and adjustments, their effects on resilience, promoting flexibility and balancing between flexibility and reliability. (Author)

  16. Environmentally Resistant Mo-Si-B-Based Coatings

    Science.gov (United States)

    Perepezko, J. H.; Sossaman, T. A.; Taylor, M.

    2017-06-01

    High-temperature applications have demonstrated aluminide-coated nickel-base superalloys to be remarkably effective, but are reaching their service limit. Alternate materials such as refractory (e.g., W, Mo) silicide alloys and SiC composites are being considered to extend high temperature capability, but the silica surfaces on these materials require coatings for enhanced environmental resistance. This can be accomplished with a Mo-Si-B-based coating that is deposited by a spray deposition of Mo followed by a chemical vapor deposition of Si and B by pack cementation to develop an aluminoborosilica surface. Oxidation of the as-deposited (Si + B)-pack coatings proceeds with partial consumption of the initial MoSi2 forming amorphous silica. This Si depletion leads to formation of a B-saturated Mo5Si3 (T1) phase. Reactions between the Mo and the B rich phases develop an underlying Mo5SiB2 (T2) layer. The T1 phase saturated with B has robust oxidation resistance, and the Si depletion is prevented by the underlying diffusion barrier (T2). Further, due to the natural phase transformation characteristics of the Mo-Si-B system, cracks or scratches to the outer silica and T1 layers can be repaired from the Si and B reservoirs of T2 + MoB layer to yield a self-healing characteristic. Mo-Si-B-based coatings demonstrate robust performance up to at least 1700 °C not only to the rigors of elevated temperature oxidation, but also to CMAS attack, hot corrosion attack, water vapor and thermal cycling.

  17. Template-free fabrication of hierarchical MoS2/MoO2 nanostructures as efficient catalysts for hydrogen production

    Science.gov (United States)

    Zhang, Xiangyong; Du, Zijie; Luo, Xiaonan; Sun, Aokui; Wu, Zhuangzhi; Wang, Dezhi

    2018-03-01

    A hierarchical MoS2/MoO2 nanostructure is presented as a highly efficient catalyst for the hydrogen evolution reaction (HER), which is prepared via a facile hydrothermal route in the absence of templates. The influence of various Mo sources has been studied and the roles of MoS2 shell and MoO2 core are discussed. It is found that the MoS2/MoO2 nanostructures derived from the MoO2 nanobelts exhibit the best HER activity, and the HER performance is strongly affected by the relative contents of MoS2 shell and MoO2 core, which correspond to the mass transport ability and the electron transfer ability, respectively.

  18. Ion bombardment effects on nucleation of sputtered Mo nano-crystals in Mo/B4C/Si multilayers

    NARCIS (Netherlands)

    Patelli, A.; Rigato, V.; Salmaso, G.; Carvalho, N. J. M.; De Hosson, J. Th. M.; Bontempi, E.; Depero, L. E.

    2006-01-01

    Over recent years, the introduction of Mo/Si multilayers mirrors with different barrier layers for the interfaces has allowed increasing mirror reflectance, life and temperature stability. The effects of these very thin barrier layers on multilayer growth, such as interlayer formation and Mo

  19. High pressure effect on MoS2 and MoSe2 single crystals grown by ...

    Indian Academy of Sciences (India)

    Unknown

    The variation of electrical resistance under pressure was monitored in a Bridgman anvil set-up up to 6⋅5 GPa to identify occurrence of any structural transition. MoS2 and MoSe2 do not undergo any structural transitions under pressure. Keywords. Single crystals; chemical vapour transport technique; high pressure. 1.

  20. Theoretical prediction of high electron mobility in multilayer MoS2 heterostructured with MoSe2

    Science.gov (United States)

    Ji, Liping; Shi, Juan; Zhang, Z. Y.; Wang, Jun; Zhang, Jiachi; Tao, Chunlan; Cao, Haining

    2018-01-01

    Two-dimensional (2D) MoS2 has been considered to be one of the most promising semiconducting materials with the potential to be used in novel nanoelectronic devices. High carrier mobility in the semiconductor is necessary to guarantee a low power dissipation and a high switch speed of the corresponding electronic device. Strain engineering in 2D materials acts as an important approach to tailor and design their electronic and carrier transport properties. In this work, strain is introduced to MoS2 through perpendicularly building van der Waals heterostructures MoSe2-MoS2. Our first-principles calculations demonstrate that acoustic-phonon-limited electron mobility can be significantly enhanced in the heterostructures compared with that in pure multilayer MoS2. It is found that the effective electron mass and the deformation potential constant are relatively smaller in the heterostructures, which is responsible for the enhancement in the electron mobility. Overall, the electron mobility in the heterostructures is about 1.5 times or more of that in pure multilayer MoS2 with the same number of layers for the studied structures. These results indicate that MoSe2 is an excellent material to be heterostructured with multilayer MoS2 to improve the charge transport property.

  1. Carbon and Mo transformations during the synthesis of mesoporous Mo2C/carbon catalysts by carbothermal hydrogen reduction

    Science.gov (United States)

    Wang, Haiyan; Liu, Shida; Liu, Bing; Montes, Vicente; Hill, Josephine M.; Smith, Kevin J.

    2018-02-01

    The synthesis of mesoporous Mo2C/carbon catalysts by carbothermal hydrogen reduction is reported. Petroleum coke (petcoke) was activated with KOH at 800 °C to obtain high surface area microporous activated petcoke (APC; 2000 m2/g). The APC was wet impregnated with ammonium heptamolybdate (AHM: 10 wt% Mo), dried and reduced in H2 at temperatures from 400 to 800 °C, to yield Mo2C/APC catalysts. Increased reduction temperature increased the Mo2C yield and the mesoporous volume of the Mo2C/APC. At a reduction temperature of 750 °C the mesopore volume of the catalyst doubled compared to the APC support and accounted for 37% of the total pore volume. Maintaining the final CHR temperature for 90 min further increased the Mo2C yield and mesoporosity of the catalyst. The role of Mo2C in the catalytic hydrogenation of the APC and mesopore generation is demonstrated. The activity of the Mo2C/carbon catalysts in the hydrodeoxygenation of 4-methyl phenol increased with increased CHR temperature and catalyst mesoporosity.

  2. Coke formation during the hydrotreatment of bio-oil using NiMo and CoMo catalysts

    NARCIS (Netherlands)

    Kadarwati, Sri; Hu, Xun; Gunawan, Richard; Westerhof, Roel; Gholizadeh, Mortaza; Hasan, M. D.Mahmudul; Li, Chun-Zhu

    2017-01-01

    This study aims to investigate the coke formation during the hydrotreatment of bio-oil at low temperature. The catalytic hydrotreatment of bio-oil produced from the pyrolysis of mallee wood was carried out using pre-sulphided NiMo and CoMo catalysts at a temperature range of 150–300 °C. Our results

  3. Preparation of MoO3/Al2O3 Catalysts with Sharp Eggshell Mo Distribution by Slurry Impregnation

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Zdražil, Miroslav

    2002-01-01

    Roč. 78, 1-4 (2002), s. 313-318 ISSN 1011-372X R&D Projects: GA ČR GA104/01/0544 Keywords : MoO3/Al2O3 catalyst * eggshell Mo catalyst * slurry impregnation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.559, year: 2002

  4. Effects of grain size and grain boundaries on defect production in nanocrystalline 3C-SiC

    International Nuclear Information System (INIS)

    Swaminathan, N.; Kamenski, Paul J.; Morgan, Dane; Szlufarska, Izabela

    2010-01-01

    Cascade simulations in single crystal and nanocrystalline SiC have been conducted in order to determine the role of grain boundaries and grain size on defect production during primary radiation damage. Cascades are performed with 4 and 10 keV silicon as the primary knock-on atom (PKA). Total defect production is found to increase with decreasing grain size, and this effect is shown to be due to increased production in grain boundaries and changing grain boundary volume fraction. In order to consider in-grain defect production, a new mapping methodology is developed to properly normalize in-grain defect production rates for nanocrystalline materials. It is shown that the presence of grain boundaries does not affect the total normalized in-grain defect production significantly (the changes are lower than ∼20%) for the PKA energies considered. Defect production in the single grain containing the PKA is also studied and found to increase for smaller grain sizes. In particular, for smaller grain sizes the defect production decreases with increasing distance from the grain boundary while for larger grain sizes the presence of the grain boundaries has negligible effect on defect production. The results suggest that experimentally observed changes in radiation resistance of nanocrystalline materials may be due to long-term damage evolution rather than changes in defect production rates from primary damage.

  5. Comparison of communities of stored product mites in grain mass and grain residues in the Czech Republic.

    Science.gov (United States)

    Hubert, Jan; Munzbergová, Zuzana; Kucerová, Zuzana; Stejskal, Václav

    2006-01-01

    In storage facilities one can find grain either in stored grain mass or in grain residues in the store corners or machinery. Although it is claimed that grain residues are serious pest reservoirs since they harbor numbers of stored product arthropods and are connected via continuous emigration with grain mass, the documentation for this is not convincing. Therefore in 78 selected grain stores, we simultaneously sampled the grain mass and residues in order to compare concurrent mite communities in these two different habitats. We found 30 species in about 614,000 individuals in residues and 23 species in about 20 000 individuals in grain mass. Canonical correspondence analysis (CCA) of transformed abundance data showed differences in the communities of mites in grain mass and residues: (i) species associated to grain residues (e.g. Tyrophagus longior, Tydeus interruptus, Acarus farris and Cheyletus eruditus) and (ii) species associated to both grain mass and grain residues (e.g. Tarsonemus granarius, Acarus siro, Tyrophagus putrescentiae, Lepidoglyphus destructor and Cheyletus malaccensis). Although the residue samples had more mites and higher species diversity than the stored grain mass, no correlation in mite abundance and species numbers between samples from grain residues and grain mass was found, thereby indicating low connectivity of these two habitats.

  6. The effect of grain source and grain processing on performance of feedlot cattle: a review.

    Science.gov (United States)

    Owens, F N; Secrist, D S; Hill, W J; Gill, D R

    1997-03-01

    Effects of grain species and grain processing method on DMI, rate and efficiency of gain, and feeding value for cattle fed high concentrate diets were appraised by statistically compiling results from 605 comparisons from feeding trials published in North American journals and experiment station bulletins since 1974. Metabolizable energy (ME) values for each grain and processing method were calculated by quadratic procedures from DMI and animal performance. Averaged across processing methods, ME values for corn, milo, and wheat grain (3.40, 3.22, and 3.46 Mcal/kg DM) fell within 9% of ME estimates from NRC (1996) for beef cattle. In contrast, ME values for barley and oats grain (3.55 and 3.46 Mcal/kg DM) were 24% and 17% greater than NRC (1996) estimates. Compared with the dry rolled forms, high moisture corn and milo resulted in lower ADG and DMI. Compared with dry rolling, either steam rolling or flaking of corn, milo, and wheat decreased DMI without decreasing ADG and improved feed efficiency by 10, 15, and 10%, respectively. Compared with dry rolled grain, steam flaking increased (P moisture content of high-moisture corn decreased dry matter intake without depressing ADG and improved efficiency and increased ME of the grain. Compared with steam flakes of moderate thinness, processing milo or barley to a very thin flake tended to reduce ADG and failed to improve feed efficiency. The ideal roughage source and roughage moisture content for maximum ME and ADG varied with grain processing method. Feeding corn silage rather than alfalfa and wet rather than dry roughage depressed (P moisture corn grain but tended to increase both with steam-flaked corn or wheat.

  7. Mo-O bond doping and related-defect assisted enhancement of photoluminescence in monolayer MoS2

    Directory of Open Access Journals (Sweden)

    Xiaoxu Wei

    2014-12-01

    Full Text Available In this work, we report a strong photoluminescence (PL enhancement of monolayer MoS2 under different treatments. We find that by simple ambient annealing treatment in the range of 200 °C to 400 °C, the PL emission can be greatly enhanced by a factor up to two orders of magnitude. This enhancement can be attributed to two factors: first, the formation of Mo-O bonds during ambient exposure introduces an effective p-doping in the MoS2 layer; second, localized electrons formed around Mo-O bonds related defective sites where the electrons can be effectively localized with higher binding energy resulting in efficient radiative excitons recombination. Time resolved PL decay measurement showed that longer lifetime of the treated sample consistent with the higher quantum efficiency in PL. These results give more insights to understand the luminescence properties of the MoS2.

  8. Local Alignments for Fine-Grained Categorization

    NARCIS (Netherlands)

    Gavves, E.; Fernando, B.; Snoek, C.G.M.; Smeulders, A.W.M.; Tuytelaars, T.

    2015-01-01

    The aim of this paper is fine-grained categorization without human interaction. Different from prior work, which relies on detectors for specific object parts, we propose to localize distinctive details by roughly aligning the objects using just the overall shape. Then, one may proceed to the

  9. Coarse grained model for semiquantitative lipid simulations

    NARCIS (Netherlands)

    Marrink, SJ; de Vries, AH; Mark, AE

    2004-01-01

    This paper describes the parametrization of a new coarse grained (CG) model for lipid and surfactant systems. Reduction of the number of degrees of freedom together with the use of short range potentials makes it computationally very efficient. Compared to atomistic models a gain of 3-4 orders of

  10. Fatigue in tension perpendicular to the grain

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben

    1999-01-01

    Traditinally fatigue resistance is quantified as number of cycles to failure at a given stress level. A previous study by the authors showed that fatigue in compression parallel to the grain is governed partly by duration of load and partly by an effect of loading, i.e. a combination of a creep...

  11. Cycling of grain legume residue nitrogen

    DEFF Research Database (Denmark)

    Jensen, E.S.

    1995-01-01

    Symbiotic nitrogen fixation by legumes is the main input of nitrogen in ecological agriculture. The cycling of N-15-labelled mature pea (Pisum sativum L.) residues was studied during three years in small field plots and lysimeters. The residual organic labelled N declined rapidly during the initial...... management methods in order to conserve grain legume residue N sources within the soil-plant system....

  12. Shock fabrics in fine-grained micrometeorites

    Science.gov (United States)

    Suttle, M. D.; Genge, M. J.; Russell, S. S.

    2017-10-01

    The orientations of dehydration cracks and fracture networks in fine-grained, unmelted micrometeorites were analyzed using rose diagrams and entropy calculations. As cracks exploit pre-existing anisotropies, analysis of their orientation provides a mechanism with which to study the subtle petrofabrics preserved within fine-grained and amorphous materials. Both uniaxial and biaxial fabrics are discovered, often with a relatively wide spread in orientations (40°-60°). Brittle deformation cataclasis and rotated olivine grains are reported from a single micrometeorite. This paper provides the first evidence for impact-induced shock deformation in fine-grained micrometeorites. The presence of pervasive, low-grade shock features in CM chondrites and CM-like dust, anomalously low-density measurements for C-type asteroids, and impact experiments which suggest CM chondrites are highly prone to disruption all imply that CM parent bodies are unlikely to have remained intact and instead exist as a collection of loosely aggregated rubble-pile asteroids, composed of primitive shocked clasts.

  13. Grain size estimation in anisotropic materials

    Czech Academy of Sciences Publication Activity Database

    Saxl, Ivan; Ponížil, P.; Sülleiová, K.

    2005-01-01

    Roč. 482, - (2005), s. 239-242 ISSN 0255-5476 R&D Projects: GA ČR(CZ) GA201/03/0946 Institutional research plan: CEZ:AV0Z10190503 Keywords : 3D grain size * profile count * intercept count Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.399, year: 2005

  14. Magnetically modified spent grain for dye removal

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Horská, Kateřina; Šafaříková, Miroslava

    2011-01-01

    Roč. 53, č. 1 (2011), s. 78-80 ISSN 0733-5210 R&D Projects: GA MŠk OC09052; GA MPO 2A-1TP1/094 Institutional research plan: CEZ:AV0Z60870520 Keywords : Spent grain * Magnetic fluid * Adsorption * Dyes Subject RIV: GM - Food Processing Impact factor: 2.073, year: 2011

  15. Fatigue mechanisms in ultrafine-grained copper

    Czech Academy of Sciences Publication Activity Database

    Lukáš, Petr; Kunz, Ludvík; Svoboda, Milan

    2009-01-01

    Roč. 47, č. 1 (2009), s. 1-9 ISSN 0023-432X R&D Projects: GA AV ČR(CZ) 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : ultrafine-grained copper * effect of purity * effect of temperature Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.345, year: 2007

  16. Pollen Grains, Random Walks and Einstein

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 3. Pollen Grains, Random Walks and Einstein. Sriram Ramaswamy. General Article Volume 5 Issue 3 March 2000 pp 16-34. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/005/03/0016-0034 ...

  17. Pollen Grains, Random Walks and Einstein

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 12. Pollen Grains, Random Walks and Einstein. Sriram Ramaswamy. Volume 10 Issue 12 December 2005 pp 106-124. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/010/12/0106-0124 ...

  18. Interstellar grains - the 75th anniversary

    International Nuclear Information System (INIS)

    Li Aigen

    2005-01-01

    The year of 2005 marks the 75th anniversary since Trumpler (1930) provided the first definitive proof of interstellar grains by demonstrating the existence of general absorption and reddening of starlight in the galactic plane. This article reviews our progressive understanding of the nature of interstellar dust

  19. Grain boundary atomic structure and properties

    Czech Academy of Sciences Publication Activity Database

    Paidar, Václav

    2002-01-01

    Roč. 8, - (2002), s. 24-30 ISSN 1335-1532 R&D Projects: GA ČR GA202/02/0916 Institutional research plan: CEZ:AV0Z1010914 Keywords : atomic structures * grain boundary properties * phase transformations Subject RIV: BM - Solid Matter Physics ; Magnetism

  20. Physical properties of sunflower grains after drying

    Directory of Open Access Journals (Sweden)

    Paulo Carteri Coradi

    2015-12-01

    Full Text Available The knowledge of the physical properties of the grains is important for the optimization of post-harvest operations. This study aimed to evaluate the effects of convective drying with different air temperatures (45, 55, 65 and 75 °C the physical properties of sunflower seeds. The drying sunflower grains was performed in convection oven with forced air. In natural conditions, samples of 5 kg of pellets were used for each repetition drying. During the drying process, the grains samples were weighed periodically until they reach 10% (wet basis, w.b., then were subjected to evaluations of physical properties. According to the results it was observed that the porosity, apparent density, thousand kernel weight to the drag coefficient, roundness, sphericity and width of sunflower seed did not change with increasing temperature drying air. It was concluded that the drying air temperatures of 45 °C and 55 retained the initial physical characteristics of sunflower seeds. The temperature of the drying air of 75 °C had greater influence on changes in volumetric shrinkage of the grains.