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Sample records for prepared grain growth

  1. KINETICS OF GRAIN-GROWTH OF YTTRIUM ALUMINUM GARNET FIBERS PREPARED BY SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    Tan H.

    2013-12-01

    Full Text Available The yttrium aluminum garnet (YAG long fibers were prepared by the sol-gel method using aluminum chloride, aluminum powder, yttrium oxide and acetic acid as raw materials. The grain growth law is given by Dn – D0n = Kt (D0 = initial grain size, D = average grain size at time t, n = grain growth exponent and K = reaction constant. The grain growth exponent and activation energy of YAG fibers are ≈ 3 and 200 kJ/mol, respectively. The grain-growth behaviors of YAG were influenced by experimental conditions such as raw materials, initial particle size, initial particle distribution, etc.

  2. Normal and abnormal grain growth in fine-grained Nd-Fe-B sintered magnets prepared from He jet milled powders

    Science.gov (United States)

    Bittner, F.; Woodcock, T. G.; Schultz, L.; Schwöbel, C.; Gutfleisch, O.; Zickler, G. A.; Fidler, J.; Üstüner, K.; Katter, M.

    2017-03-01

    Fine-grained, heavy rare earth free Nd-Fe-B sintered magnets were prepared from He jet milled powders with an average particle size of 1.5 μm by low temperature sintering at 920 °C or 980 °C. A coercivity of >1600 kA/m was achieved for an average grain size of 1.68 μm. Transmission electron microscopy showed that the distribution and composition of intergranular and grain boundary junction phases was similar to that in conventionally processed magnets. Microstructural analysis on different length scales revealed the occurrence of abnormal grain growth, which is unexpected for sintering temperatures below 1000 °C. A larger area fraction of abnormal grains was observed in the sample sintered at 920 °C compared to that sintered at 980 °C. Microtexture investigation showed a better crystallographic alignment of the abnormal grains compared to the fine-grained matrix, which is explained by a size dependent alignment of the powder particles during magnetic field alignment prior to sintering. Slightly larger particles in the initial powder show a better alignment and will act as nucleation sites for abnormal grain growth. Magneto-optical Kerr investigations confirmed the lower switching field of the abnormal grains compared to the fine-grained matrix. The demagnetisation curve of the sample sintered at 920 °C showed reduced rectangularity and this was attributed to a cooperative effect of the larger fraction of abnormal grains with low switching field and, as a minor effect, a reduced degree of crystallographic texture in this sample compared to the material sintered at 980 °C, which did not show the reduced rectangularity of the demagnetisation curve.

  3. Phase stability and grain growth in an Ag/Bi-2223 composite conductor prepared using fine-grained Bi-2223 as a precursor.

    Energy Technology Data Exchange (ETDEWEB)

    Merchant, N. N.

    1998-09-17

    We have investigated the stability and microstructural transformability of the Bi-2223 phase in a silver-sheathed monofilament composite tape fabricated using fine-grained Bi{sub 1.7}Pb{sub 0.3}Sr{sub 1.9}Ca{sub 2.0}-Cu{sub 3.0}O{sub y} (Bi-2223) as the precursor powder. The fully formed Bi-2223 precursor was prepared using established procedures. The purpose of this study was to explore the prospects for growing textured, large-grain-size Bi-2223 from the fine-grained precursor by process parameter perturbations. These perturbations included thermal ramp up variations, programmed heat treatment temperature and oxygen pressure fluctuations, and parameter manipulations during cool-down. Our results show that the types of heat treatments used in conventional oxide-powder-in-tube (OPIT) processing do not facilitate Bi-2223 grain growth when the precursor powder is preconcerted Bi-2223. We also observed that the Bi-2223 partially. decomposed during conventional thermal ramp-up in 0.075 atm O{sub 2}, but that this decomposition can be inhibited by ramping up in a reduced oxygen pressure. A pathway was found for back-reacting the fine-grained Bi-2223 (to Bi-2212, Bi-2201 and nonsuperconducting secondary phases), then reforming large-grained Bi-2223 in a colony microstructure having some distinct differences from that produced during conventional OPIT processing.

  4. Effect of annealing on microstructure, grain growth, and hardness of nanocrystalline Fe-Ni alloys prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kotan, H., E-mail: hkotan@ncsu.edu [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States); Saber, M.; Koch, C.C.; Scattergood, R.O. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer Iron-nickel powders were hardened to 9.5 GPa by the mechanism of grain refinement strengthening using ball-milling. Black-Right-Pointing-Pointer We annealed the prepared powders and observed reduced hardness and extensive grain growth above 500 Degree-Sign C. Black-Right-Pointing-Pointer The Vickers hardness as a function of the grain size was found to exhibit a Hall-Petch slope. Black-Right-Pointing-Pointer Retained austenite was observed for Fe-8Ni and Fe-10Ni alloys annealed in the two-phase region. Black-Right-Pointing-Pointer As-milled microstructure plays an important role on the formation of austenite in the two-phase region. - Abstract: Fe-xNi alloys from x = 0 to x = 15 with an as-milled grain size and hardness in the range of 8-11 nm and 8.5-9.5 GPa, respectively, were synthesized by ball milling. Microstructural changes, hardness, and grain growth due to annealing were characterized using X-ray diffractometry, microhardness, focused ion beam channeling contrast imaging, and optical microscopy. It was found that the composition range of single bcc phase was extended by ball milling. Subsequent annealing of MA samples resulted in reduction of hardness and extensive grain growth. It indicates that nickel has no significant effect on thermal stabilization of iron. Retained austenite was observed for Fe-8Ni and Fe-10Ni alloys annealed in the two-phase region and effect of as-milled structure on retained austenite formation was discussed.

  5. Doping Effect on the Grain Growth of Spinel LiMn2O4 Prepared by Sol-Gel Methods

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The cathode-active materials, Li1+yMn2-xO4 (M = A1, Co, Ni, Zn, y = 0.02, x = 0.02) powder, were synthesized by sol-gel method using LiOH, Mn(NO3)2 as the starting materials, citric acid as a carrier and A1(NO3)3·9H2O or Co(NO3)2·6H2O or Ni(NO3)2·6H2O or Zn(NO3)2·6H2O as dopants. The influence of different doping elements on the structural properties of the as-prepared samples was investigated by X-ray diffraction (XRD), infrared (IR) spectroscopy and scanning electron microscopy (SEM). X-ray diffraction patterns of the prepared samples were identified as the spinel structure with space group Fd3m. The grain size increases gradually as the sintering temperature rises and corresponding activation energies for the grain growth have been estimated using Arrhenius' empirical relation.

  6. 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.

  7. Microbial growth in dry grain food (Sunsik) beverages prepared with water, milk, soymilk, or honey-water.

    Science.gov (United States)

    Jung, Jin-Ho; Lee, Sun-Young

    2010-05-01

    This study was conducted to investigate the growth of microorganisms, including pathogenic bacteria such as Cronobacter sakazakii and Bacillus cereus, in Sunsik beverages made of water, milk, soymilk, or honey-water during storage at room temperature. Prepared Sunsik beverages were stored at room temperature and the growth of total aerobic counts, Escherichia coli/coliforms, and yeast and mold were measured. Also, samples inoculated with a cocktail of C. sakazakii or B. cereus spores were stored at room temperature and their growths were determined during storage. Populations of total aerobic counts and coliforms significantly increased with increasing storage time at room temperature, which resulted in higher than 8 log and 7 log after 24 h in all samples except for the honey-water sample, respectively. Levels of total aerobic counts and coliforms were significantly lower in the honey-water sample than in the other samples after 6 and 9 h of storage, respectively. Initial populations of C. sakazakii and B. cereus ranged from 0 to 1 log CFU/mL, respectively, and these populations significantly increased with increasing storage time at room temperature. Therefore, populations of C. sakazakii and B. cereus were approximately 7 to 8 log CFU/mL after 24 h of storage. However, after 12 and 9 h of storage, there were significant differences in levels of C. sakazakii and B. cereus between the honey-water sample and the other samples, respectively. Based on these results, the addition of honey can inhibit microbial growth in Sunsik beverages; however, the best way to avoid pathogen infection would be to consume Sunsik beverages as soon as possible after preparation.

  8. Competitive growth of high purity aluminum grains in directional solidification

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jiao; SHU Da; WANG De-lin; SUN Bao-de; CHEN Gang

    2006-01-01

    A self-made directional solidification setup was used to prepare high purity aluminum ingots of 100mm in diameter. The morphology of the growth interface was detected by SEM and AFM, and the grain lattice orientation was detected by XRD. The results indicate that the grains suffer competitive growth under any conditions in experiments. The lattice orientation of the preferred grains is determined by the flow field above the solid-liquid interface. The horizontal lattice position does not change during the growth process. However, the lattice orientation in the growth direction varies with the growth velocity and approaches to [100]gradually during the growth process.

  9. 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.

  10. Kinetic constants of abnormal grain growth in nanocrystalline nickel

    Science.gov (United States)

    Aleshin, A. N.

    2016-02-01

    The grain growth in nanocrystalline nickel with a purity of 99.5 at % during non-isothermal annealing was experimentally investigated using differential scanning calorimetry and transmission electron microscopy. Nanocrystalline nickel was prepared by electrodeposition and had an average grain size of approximately 20 nm. It was shown that, at a temperature corresponding to the calorimetric signal peak, abnormal grain growth occurs with the formation of a bimodal grain microstructure. Calorimeters signals were processed within the Johnson-Mehl-Avrami formalism. This made it possible to determine the exponent of the corresponding equation, the frequency factor, and the activation energy of the grain growth, which was found to be equal to the activation energy of the vacancy migration. The reasons for the abnormal grain growth in nanocrystalline nickel were discussed.

  11. 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.

  12. Strength of Rocks Affected by Deformation Enhanced Grain Growth

    Science.gov (United States)

    Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.

    2005-12-01

    One way of looking into the possibility of long-term strength changes in the lithosphere is to study transient effects resulting from modifications of the microstructure of rocks. It is generally accepted that mechanical weakening may occur due to progressive grain size refinement resulting from dynamic recrystallization. A decrease in grain size may induce a switch from creep controlled by grain size insensitive dislocation mechanisms to creep governed by grain size sensitive (GSS) mechanisms involving diffusion and grain boundary sliding processes. This switch forms a well-known scenario to explain localization in the lithosphere. However, fine-grained rocks in localized deformation zones are prone to grain coarsening due to surface energy driven grain boundary migration (SED-GBM). This might harden the rock, affecting its role in localizing strain in the long term. The question has arisen if grain growth by SED-GBM in a rock deforming in the GSS creep field can be significantly affected by strain. The broad aim of this study is to shed more light onto this. We have experimentally investigated the microstructural and strength evolution of fine-grained (~0.6 μm) synthetic forsterite and Fe-bearing olivine aggregates that coarsen in grain size while deforming by GSS creep at elevated pressure (600 MPa) and temperature (850-1000 °C). The materials were prepared by `sol-gel' method and contained 0.3-0.5 wt% water and 5-10 vol% enstatite. We performed i) static heat treatment tests of various time durations involving hot isostatic pressing (HIP), and ii) heat treatment tests starting with HIP and continuing with deformation up to 45% axial strain at strain rates in the range 4x10-7 - 1x10-4 s-1. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. In addition to the experiments, we studied microstructural evolution in simple two-dimensional numerical models, combining deformation and SED-GBM by means of the

  13. Topological Transformation during Normal Grain Growth

    Institute of Scientific and Technical Information of China (English)

    Chaogang LOU; Michael A.Player

    2004-01-01

    This paper investigates topological transformation during normal grain growth by carrying out a computer vertex simulation.Results show that topological correlation agrees with the models proposed by Blanc et al. and Weaire. Topological transformation occurs more often on grains with some topological classes instead of equal probability on each boundary. This can be qualitatively explained by topological correlation.

  14. 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...

  15. Fabrication and electrical properties of textured strontium(0.53)barium(0.47)niobium(2)oxygen(6) ceramics prepared by templated grain growth

    Science.gov (United States)

    Duran, Cihangir

    Sr0.53Ba0.47Nb2O6 (SBN53) ceramics were textured by the templated grain growth (TGG), in a matrix of SrNb2O6 and BaNb2O6 powders. Acicular KSr2Nb5O15 (KSN) template particles, synthesized by a molten salt process, were used to texture the samples in the c direction (i.e., [001]). Template growth was assisted by adding V2O5 as a liquid phase former for some compositions. The texture fraction also increased with higher sintering temperatures or times and with initial template concentration due to the preferential growth of the template particles. When V2O5 was present, SBN53 phase formation initiated on the KSN templates and texture development started at temperatures as low as 950°C. Phase formation in the V2O5-free samples, however, initiated in the matrix (i.e., independent of the KSN templates). The liquid phase adversely affected the template growth by favoring anisotropic grain growth in the matrix, which caused lower texture fraction and broader texture distribution in [001] at low template concentrations. Increased template-template interaction (e.g., tangling) during tape casting also resulted in broader texture distribution. Therefore, an optimum template content was found to be ˜10--15 wt%. However, a texture fraction of 0.93 to 0.98 was obtained using only 5 wt% templates when anisotropic matrix grain growth was prevented. Phase evolution was studied in the randomly oriented samples as a function of quenching temperature, heating rate, and liquid phase, using KSN powder (rather than acicular particles) as a seed material. The formation temperature for SBN53 was lowered substantially by adding more seeds, decreasing the heating rate, and introducing a liquid. The temperature decreased from 1260°C for the samples with no seeds to 1130°C for the samples with 15.4 wt% seeds + 0.8 mol% V2O5 at a heating rate of 4°C/min. For the V2O5-free samples, the activation energy was considerably lowered from 554 +/- 15 kJ/mol for the samples with no seeds to 241

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

    Science.gov (United States)

    Svoboda, J.; Fischer, F. D.

    2014-01-01

    Abnormal grain growth as the abrupt growth of a group of the largest grains in a multi-grain system is treated within the context of unequal retardation of grain growth due to the segregation of solute atoms from the bulk of the grains into the grain boundaries. During grain boundary migration, the segregated solute atoms are dragged under a small driving force or left behind the migrating grain boundary under a large driving force. Thus, the solute atoms in the grain boundaries of large grains, exhibiting a large driving force, can be released from the grain boundary. The mobility of these grain boundaries becomes significantly higher and abnormal grain growth is spontaneously provoked. The mean-field model presented here assumes that each grain is described by its grain radius and by its individual segregation parameter. The thermodynamic extremal principle is engaged to obtain explicit evolution equations for the radius and segregation parameter of each grain. Simulations of grain growth kinetics for various conditions of segregation with the same initial setting (100 000 grains with a given radius distribution) are presented. Depending on the diffusion coefficients of the solute in the grain boundaries, abnormal grain growth may be strongly or marginally pronounced. Solute segregation and drag can also significantly contribute to the stabilization of the grain structure. Qualitative agreement with several experimental results is reported.

  17. Parsing abnormal grain growth in specialty aluminas

    Science.gov (United States)

    Lawrence, Abigail Kremer

    Grain growth in alumina is strongly affected by the impurities present in the material. Certain impurity elements are known to have characteristic effects on abnormal grain growth in alumina. Specialty alumina powders contain multiple impurity species including MgO, CaO, SiO2, and Na 2O. In this work, sintered samples made from alumina powders containing various amounts of the impurities in question were characterized by their grain size and aspect ratio distributions. Multiple quantitative methods were used to characterize and classify samples with varying microstructures. The grain size distributions were used to partition the grain size population into subpopulations depending on the observed deviation from normal behavior. Using both grain size and aspect ratio a new visual representation for a microstructure was introduced called a morphology frequency map that gives a fingerprint for the material. The number of subpopulations within a sample and the shape of the distribution on the morphology map provided the basis for a classification scheme for different types of microstructures. Also using the two parameters a series of five metrics were calculated that describe the character of the abnormal grains in the sample, these were called abnormal character values. The abnormal character values describe the fraction of grains that are considered abnormal, the average magnitude of abnormality (including both grain size and aspect ratio), the average size, and variance in size. The final metric is the correlation between grain size and aspect ratio for the entire population of grains. The abnormal character values give a sense of how different from "normal" the sample is, given the assumption that a normal sample has a lognormal distribution of grain size and a Gaussian distribution of aspect ratios. In the second part of the work the quantified measures of abnormality were correlated with processing parameters such as composition and heat treatment conditions. A

  18. Linear grain growth kinetics and rotation in nanocrystalline Ni

    OpenAIRE

    Farkas, Diana; Mohanty, S.; Monk, J.

    2007-01-01

    We report three-dimensional atomistic molecular dynamics studies of grain growth kinetics in nanocrystalline Ni. The results show the grain size increasing linearly with time, contrary to the square root of the time kinetics observed in coarse-grained structures. The average grain boundary energy per unit area decreases simultaneously with the decrease in total grain boundary area associated with grain growth. The average mobility of the boundaries increases as the grain size increases. The r...

  19. Assessment of MARMOT Grain Growth Model

    Energy Technology Data Exchange (ETDEWEB)

    Fromm, B. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation Dept.; Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation Dept.; Schwen, D. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation Dept.; Brown, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pokharel, R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-01

    This report assesses the MARMOT grain growth model by comparing modeling predictions with experimental results from thermal annealing. The purpose here is threefold: (1) to demonstrate the validation approach of using thermal annealing experiments with non-destructive characterization, (2) to test the reconstruction capability and computation efficiency in MOOSE, and (3) to validate the grain growth model and the associated parameters that are implemented in MARMOT for UO2. To assure a rigorous comparison, the 2D and 3D initial experimental microstructures of UO2 samples were characterized using non-destructive Synchrotron x-ray. The same samples were then annealed at 2273K for grain growth, and their initial microstructures were used as initial conditions for simulated annealing at the same temperature using MARMOT. After annealing, the final experimental microstructures were characterized again to compare with the results from simulations. So far, comparison between modeling and experiments has been done for 2D microstructures, and 3D comparison is underway. The preliminary results demonstrated the usefulness of the non-destructive characterization method for MARMOT grain growth model validation. A detailed analysis of the 3D microstructures is in progress to fully validate the current model in MARMOT.

  20. Grain growth by Ordered Coalescence of crystallites in Ceramics : Grain Growth Mechanisms, Microstructure Evolution and Sintering

    OpenAIRE

    Hu, Jianfeng

    2013-01-01

    Grain growth and densification process play the two most crucial roles on the microstructure evolution and the achieved performances during sintering of ceramics. In this thesis, the grain growth of SrTiO3, BaTiO3-SrTiO3 solid solutions and Si3N4 ceramics during spark plasma sintering (SPS) were investigated by electron microscopy. SrTiO3 ceramics starting from nanopowders were fabricated by SPS. A novel grain growth mechanism was discovered and named as ordered coalescence (OC) of nanocrysta...

  1. Phenomenology of Abnormal Grain Growth in Systems with Nonuniform Grain Boundary Mobility

    Science.gov (United States)

    DeCost, Brian L.; Holm, Elizabeth A.

    2017-06-01

    We have investigated the potential for nonuniform grain boundary mobility to act as a persistence mechanism for abnormal grain growth (AGG) using Monte Carlo Potts model simulations. The model system consists of a single initially large candidate grain embedded in a matrix of equiaxed grains, corresponding to the abnormal growth regime before impingement occurs. We assign a mobility advantage to grain boundaries between the candidate grain and a randomly selected subset of the matrix grains. We observe AGG in systems with physically reasonable fractions of fast boundaries; the probability of abnormal growth increases as the density of fast boundaries increases. This abnormal growth occurs by a series of fast, localized growth events that counteract the tendency of abnormally large grains to grow more slowly than the surrounding matrix grains. Resulting abnormal grains are morphologically similar to experimentally observed abnormal grains.

  2. Microstructure Evolution and Grain Growth Kinetics in Annealed Nanocrystalline Chromium

    Energy Technology Data Exchange (ETDEWEB)

    Chojnowski, Grzegorz [Warsaw University; Przenioslo, Radoslaw [Warsaw University; Sosnowska, Izabela [Warsaw University; Bukowski, Mirko [University of Saarbrucken, Saarbrucken, Germany; Natter, Harald [University of Saarbrucken, Saarbrucken, Germany; Hempelmann, Rolf [University of Saarbrucken, Saarbrucken, Germany; Fitch, Andrew [European Synchrotron Radiation Facility (ESRF); Urban, Volker S [ORNL

    2007-01-01

    The kinetics of thermal evolution of the microstructure of nanocrystalline chromium (nano-Cr) has been studied by time-resolved synchrotron radiation techniques: high-resolution powder diffraction and small-angle X-ray scattering (SAXS). The as-prepared electrodeposited nano-Cr with average grain size of 27 nm shows the same bcc structure as {alpha}-Cr. The nano-Cr cubic lattice parameter thermal expansion is the same as that of reference polycrystalline {alpha}-Cr. Annealing of nano-Cr at temperatures above 400 C leads to a grain growth process with the final grain size not exceeding 125 nm even at a temperature of 700 C. The single power-law behavior is observed by SAXS in as-prepared nano-Cr changes during annealing above 400 C. In nano-Cr samples annealed at temperatures between 400 and 700 C, the low-q part of the SAXS signal shows a Porod-type behavior while the high-q part shows a power-law Q-{alpha} with the exponent {alpha} < 4. This effect is probably due to changes of the grain surface roughness during grain growth.

  3. Abnormal grain growth in undoped strontium and barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Baeurer, M., E-mail: m.baeurer@ikm.uka.de [Institut fuer Keramik im Maschinenbau, Universitaet Karlsruhe, Karlsruhe (Germany); Shih, S.-J.; Bishop, C. [Department of Materials, University of Oxford, Oxford (United Kingdom); Harmer, M.P. [Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA (United States); Cockayne, D. [Department of Materials, University of Oxford, Oxford (United Kingdom); Hoffmann, M.J. [Institut fuer Keramik im Maschinenbau, Universitaet Karlsruhe, Karlsruhe (Germany)

    2010-01-15

    Abnormal grain growth is a commonly observed phenomenon in perovskite materials. In order to study this phenomenon, grain growth experiments were conducted over a temperature range from 1425 to 1600 deg. C for the model system SrTiO{sub 3} to analyse the nucleation of abnormal grains and to identify the growth mechanism involved for normal and abnormal grains. Grain boundaries of normal and abnormal grains were investigated in quenched samples by high-resolution transmission electron microscopy and by energy-dispersive spectroscopy in a scanning transmission electron microscope. No amorphous film was observed at the grain boundaries for either normal or abnormal grains. Non-stoichiometry at the grain boundaries was identified as a possible reason for the differences in growth speed. The results are compared to the nucleation and growth of abnormal grains in BaTiO{sub 3}.

  4. Oriented grain growth in ZnO thin films by Iodine doping

    Science.gov (United States)

    Thomas, Deepu; Vattappalam, Sunil C.; Mathew, Sunny; Augustine, Simon

    2015-02-01

    ZnO thin films were prepared by Successive Ionic Layer Adsorption Reaction (SILAR) method. Oriented grain growth in Iodine doped ZnO thin films were studied. The oriented grain growth in samples was studied by comparing the peak intensities from X-ray diffraction data and surface morphology by scanning electron microscopy. It is found that oriented grain growth significantly enhanced by Iodine doping. When the oriented grain growth increases, crystallinity of the thin film improves, resistance and band gap decrease. ZnO thin films having good crystallinity with preferential (002) orientation is a prerequisite for the fabrication of devices like UV diode lasers, acoustic- optic devices etc. A possible mechanism for the oriented grain growth is also investigated. It is inferred that creation of point defects is responsible for the enhanced oriented grain growth in ZnO thin films when doped with iodine.

  5. Grain growth and experimental deformation of fine-grained ice aggregates

    Science.gov (United States)

    Diebold, Sabrina; de Bresser, Hans; Spiers, Chris; Durham, William B.; Stern, Laura

    2010-05-01

    Ice is one of the most abundant materials in our solar system. It is the principal constituent of most of the moons of the outer solar system. Thus, the flow behavior of ice is of great interest when studying geodynamic processes on icy moons. Grain growth is an elementary process that is assumed to be important in the ice sheet layering of planetary moons, where temperatures 100-273 K exist. We concentrate on the questions to what extent grain growth may influence the evolution of strength of deforming ice and if the grain growth process is independent or dependent of deformation. The answers to these questions will help us to quantitatively test the hypothesis that the progressive evolution of the grain (crystal) size distribution of deforming and recrystallizing ice directly affects its rheological behaviour in terms of composite grain-size-sensitive (GSS) and grain-size-insensitive (GSI) creep, and that this might, after time, result in a steady state balance between mechanisms of GSS and GSI creep. We performed static grain growth experiments at different temperatures and a pressure (P) of 1 atm, and deformation experiments at P = 30-100 MPa starting in the GSS-creep field. The starting material ice Ih has a grain size growth tests a Hart Scientific temperature bath was filled with d-Limonene as cooling medium. The ice specimens were put into sealed alumina cylinders. For the grain growth tests, temperatures (T) between 213 K and 268 K were chosen. The durations of these tests varied between one day and two weeks. For the deformation experiments, temperatures of > 170 K and strain rates between 10-8 s-1 and 10-4 s-1 were chosen. Grain sizes, grain size distributions and grain topologies were measured by cryogenic SEM and image analysis techniques. We found clear evidence of grain growth and a significantly T-dependent variation of grain size distributions. The observations allow us to calibrate values for the grain size exponent n and the activation energy Q

  6. Grain Growth Behavior in Sintered Nd-Fe-B Magnets

    Institute of Scientific and Technical Information of China (English)

    Liu Xianglian; Zhou Shouzeng

    2007-01-01

    The Nd2Fe14B grain growth behavior in sintered Nd-Fe-B magnets was quantitatively described. The effects of sintering temperature and time, and alloy powder size and its distribution on grain growth process were analyzed. Hence, possible grain growth mechanisms in these magnets were qualitatively discussed. The Nd2Fe14B grain growth proceeded at quite a high rate in the initial 0~1 h of sintering and from then onwards the grain growth rate decreased. A large average particle size or a wide particle size distribution of initial alloy powders was found to remarkably accelerate the grain growth process and even result in the occurrence of abnormal grain growth. On the basis of experimental results, two grain growth mechanisms were considered to operate during sintering of Nd-Fe-B magnets, that is, dissolution and re-precipitation of Nd2Fe14B particles, and Nd2Fe14B particle growth by coalescence. It was believed that Nd2Fe14B particle growth by coalescence not only produced a large average grain size and a wide grain size distribution, but also was the fundamental reason for the formation of abnormally large grains in the microstructure of sintered Nd-Fe-B magnets.

  7. Textures and grain growth in nanocrystalline Fe-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seo, J.H.; Kim, J.K.; Park, Y.B. [Dept. of Materials Science and Metallurgical Engineering, Nanomaterials Research Center, Sunchon National Univ. (Korea); Yim, T.H. [Production Technology Center, Korea Inst. of Industrial Technology, Chonan (Korea)

    2005-07-01

    The texture evolution due to grain growth that takes place during annealing was investigated in nanocrystalline Fe-Ni alloys fabricated by using a continuous electroforming method. In the current materials, grain growth occurred during annealing at much lower temperatures than in conventional coarse-grained counterparts. With regard to the macrotextures, the as-deposited textures were of fibre-type characterized by strong <100>//ND and weak <111>//ND components, and the occurrence of grain growth resulted in the strong development of the <111>//ND fibre texture with the minor <100>//ND components. It was clarified using orientation imaging microscopy that abnormal growth of the <111>//ND grains in the early stages of grain growth plays an important role on the texture evolution. The origin of the abnormal grain growth has been discussed in terms of the orientation dependence of energy density. (orig.)

  8. Irradiation-induced grain growth and defect evolution in nanocrystalline zirconia with doped grain boundaries.

    Science.gov (United States)

    Dey, Sanchita; Mardinly, John; Wang, Yongqiang; Valdez, James A; Holesinger, Terry G; Uberuaga, Blas P; Ditto, Jeff J; Drazin, John W; Castro, Ricardo H R

    2016-06-22

    Grain boundaries are effective sinks for radiation-induced defects, ultimately impacting the radiation tolerance of nanocrystalline materials (dense materials with nanosized grains) against net defect accumulation. However, irradiation-induced grain growth leads to grain boundary area decrease, shortening potential benefits of nanostructures. A possible approach to mitigate this is the introduction of dopants to target a decrease in grain boundary mobility or a reduction in grain boundary energy to eliminate driving forces for grain growth (using similar strategies as to control thermal growth). Here we tested this concept in nanocrystalline zirconia doped with lanthanum. Although the dopant is observed to segregate to the grain boundaries, causing grain boundary energy decrease and promoting dragging forces for thermally activated boundary movement, irradiation induced grain growth could not be avoided under heavy ion irradiation, suggesting a different growth mechanism as compared to thermal growth. Furthermore, it is apparent that reducing the grain boundary energy reduced the effectiveness of the grain boundary as sinks, and the number of defects in the doped material is higher than in undoped (La-free) YSZ.

  9. Grain growth in nanocrystalline Ni-20%Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.B.; Park, J.; Kim, S.S. [Dept. of Materials Science and Metallurgical Engineering, Sunchon National Univ., Sunchon (Korea); Yim, T.H. [Materials Process Technology R and D Center, Korea Inst. of Industrial Technology, Chonan (Korea)

    2001-07-01

    Grain growth was investigated in a nanocrystalline Ni-20wt-%Fe alloy fabricated by an electrodeposition method, and its effect on the texture evolution was examined. The as-deposited specimens revealed a strong {l_brace}100{r_brace} and a weak {l_brace}111{r_brace} fibre-type textures. Grain growth in the material occurred on annealing beyond 370 C and resulted in the texture change that the {l_brace}111{r_brace} fibre strongly developed at the expense of the {l_brace}100{r_brace} fibre. It was observed using orientation imaging microscopy (OIM) that the {l_brace}111{r_brace} grains are much coarser than other oriented grains in the early stages of grain growth. The relationship between the texture evolution and the microstructural change accompanied by grain growth is interpreted and discussed in terms of the orientation dependency of grain growth. (orig.)

  10. Modification of computer simulation of normal grain growth

    Institute of Scientific and Technical Information of China (English)

    李剑; 李世晨; 郑子樵; 刘祖耀; 陈大钦

    2004-01-01

    A set of principles on transition probability was supplied for the physical process of grain growth. In accord with these principles, a modified transition probability considering the influence of temperature was put forward to simulate the normal grain growth relying on temperature and second phase particles. The modified transition probability correctly reflects the dependence of grain growth on the temperature. The effect of different shapes of second phase particles on the grain growth process was taken into account using the modified transition probability.The relationship between the area fraction of second phase particles and the limit of grain size of the matrix was given. The microstructural evolution patterns employed to 2-D were given. The results agree well with the real grain growth process. All these suggest that the modified transition probability is better than the conventional one.

  11. Appraisal on Textured Grain Growth and Photoconductivity of ZnO Thin Film SILAR

    OpenAIRE

    Deepu Thomas; Sunil C. Vattappalam; Sunny Mathew; Simon Augustine

    2014-01-01

    ZnO thin films were prepared by successive ionic layer adsorption reaction (SILAR) method. The textured grain growth along c-axis in pure ZnO thin films and doped with Sn was studied. The structural analysis of the thin films was done by X-ray diffraction and surface morphology by scanning electron microscopy. Textured grain growth of the samples was measured by comparing the peak intensities. Textured grain growth and photo current in ZnO thin films were found to be enhanced by doping with S...

  12. Simulation of Ceramic Grain Growth in Three Dimensions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Microstructural evolutions of ceramic grain growth at atomistic scale were modeled. The simulation was preceded with Monte-Carlo method, using Visual C++ and OpenGL languages. Realistic images in series were monitored both in two d imensions and three dimensions. Simulated image of grain growth in this series i s presented in left figure with N 0=25, r=0.40 nm, α=0.1, T=1 300 ℃, and P 0=50 %. It was seen that the average grain size increases wit h the time of grain growth. It is in good agreement with t...

  13. Steady-state grain growth in UO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Galinari, C.M.; Lameiras, F.S. [CDTN/CNEN, Belo Horizonte (Brazil)

    1998-06-05

    The authors have observed steady-state grain growth in sintered UO{sub 2} pellets of nuclear purity at 2,003 K under H{sub 2}. The behavior of the grain size distribution at different instants is consistent with the grain growth model proposed by one of the authors. The total number of grains was estimated using the Saltykov`s method, and the evolution is in accordance with the model proposed by Rhines and Craig. The parabolic growth law was observed for the mean intercept length with n = 0.4.

  14. Computer-aided analysis of grain growth in metals

    DEFF Research Database (Denmark)

    Klimanek, P.; May, C.; Richter, H.

    1993-01-01

    Isothermal grain growth in aluminium, copper and alpha-iron was investigated experimentally at elevated temperatures and quantitatively interpreted by computer simulation on the base of a statistical model described in [4,5,6]. As it is demonstrated for the grain growth kinetics, the experimental...

  15. Activation energies of grain growth mechanisms in aluminum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Alan [Lawrence Livermore National Laboratory, Chemistry and Materials Science, CA (United States)]. E-mail: jankowski1@11nl.gov; Ferreira, James [Lawrence Livermore National Laboratory, Chemistry and Materials Science, CA (United States); Hayes, Jeffrey [Lawrence Livermore National Laboratory, Mechanical Engineering, Livermore, CA 94551-9900 (United States)

    2005-11-22

    To produce a specific grain size in metallic coatings requires precise control of the time at temperature during the deposition process. Aluminum coatings are deposited using electron-beam evaporation onto heated substrate surfaces of both mica and lithium flouride. The grain size of the coating is determined upon examination of the microstructure in plan view and cross-section. Ideal grain growth is observed over the entire experimental range of temperature examined from 413 to 843 K. A transition in the activation energy for grain growth from 0.87 to 2.04 eV atom{sup -1} is observed as the temperature increases from < 526 K to > 588 K. The transition is indicative of the dominant mechanism for grain growth shifting with increasing temperature from grain boundary to lattice diffusion.

  16. A novel computer simulation for modeling grain growth

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.Q. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering)

    1995-01-01

    In this paper, the author proposes a new computer simulation model for investigating grain growth kinetics, born from the recent work on the domain growth kinetics of a quenched system with many non-conserved order parameters. A key new feature of this model for studying grain growth is that the grain boundaries are diffuse, as opposed to previous meanfield and statistical theories and Monte-Carlo simulations which assumed that grain boundaries were sharp. Unlike the Monte-Carlo simulations in which grain boundaries are made up of kinks, grain boundaries in the continuum model are smooth. Below, he describes this model in detail, give prescriptions for computer simulation, and then present computer simulation results on a two-dimensional model system.

  17. Grain growth in Al-2% Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, J.E. Jr. (Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)); Frear, D.R. (Sandia National Labs., Albuquerque, NM (United States)); Morris, J.W. Jr. (Lawrence Berkeley Lab., CA (United States))

    1991-06-01

    The grain size and grain growth kinetics in sputter deposited Al-2% Cu films on silicon substrates were determined by TEM for various film thicknesses and anneal times, temperatures and methods. Grain sizes were found to be typically lognormally distributed. The as- deposited grain size (d{sub o}) dependence on film thickness (TH) was found to be d{sub o} = C TH{sup {1/2}}, due to competitive grain growth during film formation. Annealed grain size (d) after Rapid Thermal Annealing (RTA) for time (t) at temperature (T) is described by the general equation d {minus} do = C TH{sup 0.7} {l brace}t exp ({minus}{Delta}E{sub a}/kT){r brace}{sup 1/8}, where {Delta}E{sub a} = 0.85 ev for 0.4 {mu}m films and {Delta}E{sub a} = 1.1 ev for 0.8 {mu}m films. Grain growth is largely saturated for these anneals. Grain growth is shown to be more extensive during RTA anneals than furnace annealing and more extensive in 0.4 {mu}m films than 0.8 {mu}m films for equivalent RTA cycles. The results are discussed in terms of models, simulations and previous results of grain growth in thin metal films. 21 refs., 4 figs.

  18. Appraisal on Textured Grain Growth and Photoconductivity of ZnO Thin Film SILAR

    Directory of Open Access Journals (Sweden)

    Deepu Thomas

    2014-01-01

    Full Text Available ZnO thin films were prepared by successive ionic layer adsorption reaction (SILAR method. The textured grain growth along c-axis in pure ZnO thin films and doped with Sn was studied. The structural analysis of the thin films was done by X-ray diffraction and surface morphology by scanning electron microscopy. Textured grain growth of the samples was measured by comparing the peak intensities. Textured grain growth and photo current in ZnO thin films were found to be enhanced by doping with Sn. ZnO thin film having good crystallinity with preferential (002 orientation is a semiconductor with photonic properties of potential benefit to biophotonics. From energy dispersive X-ray analysis, it is inferred that oxygen vacancy creation is responsible for the enhanced textured grain growth in ZnO thin films.

  19. Grain-growth kinetics of nanocrystalline iron studied in situ by synchrotron real-time X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Natter, H.; Schmelzer, M.; Loeffler, M.S.; Krill, C.E.; Fitch, A.; Hempelmann, R.

    2000-03-23

    Pulsed electrodeposition (PED) is used to prepare nanocrystalline iron with an average grain size of 19 nm and thermal stability up to 550 K. At 663 K {le} T {le} 783 K the kinetics of grain growth, with respect to size and size distribution, is studied in situ by means of real-time synchrotron X-ray diffraction. The Bragg peak line shapes of the large number of diffractograms are analyzed using a Warren/Averback procedure improved with respect to reliability and efficiency. The authors observe two regimes of grain growth: at less elevated temperatures grain growth is smooth and moderate up to limiting size values between 50 and 100 nm, depending on temperature. The initially rather narrow width of the size distribution increases slightly, and the activation energy of grain growth, about 100 kJ/mol, corresponds to the literature value for grain boundary self-diffusion in nanocrystalline Fe. At higher temperatures the grains grow first rapidly and then slowly up to limiting values between 200 and 400 nm, depending on temperature. The size distribution becomes rather broad, and the activation energy for grain growth, about 175 kJ/mol, corresponds to the literature value for grain boundary self-diffusion in coarse-grained polycrystalline Fe. The authors do not find evidence of a change of the type of distribution which indicates normal grain growth. The quality of the diffraction data allows a critical evaluation of different kinetic models of grain growth.

  20. Grain growth kinetics for B2O3-doped ZnO ceramics

    Directory of Open Access Journals (Sweden)

    Yuksel Berat

    2015-06-01

    Full Text Available Grain growth kinetics in 0.1 to 2 mol % B2O3-added ZnO ceramics was studied by using a simplified phenomenological grain growth kinetics equation Gn = K0 · t · exp(-Q/RT together with the physical properties of sintered samples. The samples, prepared by conventional ceramics processing techniques, were sintered at temperatures between 1050 to 1250 °C for 1, 2, 3, 5 and 10 hours in air. The kinetic grain growth exponent value (n and the activation energy for the grain growth of the 0.1 mol % B2O3-doped ZnO ceramics were found to be 2.8 and 332 kJ/mol, respectively. By increasing B2O3 content to 1 mol %, the grain growth exponent value (n and the activation energy decreased to 2 and 238 kJ/mol, respectively. The XRD study revealed the presence of a second phase, Zn3B2O6 formed when the B2O3 content was > 1 mol %. The formation of Zn3B2O6 phase gave rise to an increase of the grain growth kinetic exponent and the grain growth activation energy. The kinetic grain growth exponent value (n and the activation energy for the grain growth of the 2 mol % B2O3-doped ZnO ceramics were found to be 3 and 307 kJ/mol, respectively. This can be attributed to the second particle drag (pinning mechanism in the liquid phase sintering.

  1. Lattice Boltzmann models for the grain growth in polycrystalline systems

    Directory of Open Access Journals (Sweden)

    Yonggang Zheng

    2016-08-01

    Full Text Available In the present work, lattice Boltzmann models are proposed for the computer simulation of normal grain growth in two-dimensional systems with/without immobile dispersed second-phase particles and involving the temperature gradient effect. These models are demonstrated theoretically to be equivalent to the phase field models based on the multiscale expansion. Simulation results of several representative examples show that the proposed models can effectively and accurately simulate the grain growth in various single- and two-phase systems. It is found that the grain growth in single-phase polycrystalline materials follows the power-law kinetics and the immobile second-phase particles can inhibit the grain growth in two-phase systems. It is further demonstrated that the grain growth can be tuned by the second-phase particles and the introduction of temperature gradient is also an effective way for the fabrication of polycrystalline materials with grained gradient microstructures. The proposed models are useful for the numerical design of the microstructure of materials and provide effective tools to guide the experiments. Moreover, these models can be easily extended to simulate two- and three-dimensional grain growth with considering the mobile second-phase particles, transient heat transfer, melt convection, etc.

  2. Lattice Boltzmann models for the grain growth in polycrystalline systems

    Science.gov (United States)

    Zheng, Yonggang; Chen, Cen; Ye, Hongfei; Zhang, Hongwu

    2016-08-01

    In the present work, lattice Boltzmann models are proposed for the computer simulation of normal grain growth in two-dimensional systems with/without immobile dispersed second-phase particles and involving the temperature gradient effect. These models are demonstrated theoretically to be equivalent to the phase field models based on the multiscale expansion. Simulation results of several representative examples show that the proposed models can effectively and accurately simulate the grain growth in various single- and two-phase systems. It is found that the grain growth in single-phase polycrystalline materials follows the power-law kinetics and the immobile second-phase particles can inhibit the grain growth in two-phase systems. It is further demonstrated that the grain growth can be tuned by the second-phase particles and the introduction of temperature gradient is also an effective way for the fabrication of polycrystalline materials with grained gradient microstructures. The proposed models are useful for the numerical design of the microstructure of materials and provide effective tools to guide the experiments. Moreover, these models can be easily extended to simulate two- and three-dimensional grain growth with considering the mobile second-phase particles, transient heat transfer, melt convection, etc.

  3. Grain Growth in Samples of Aluminum Containing Alumina Particles

    DEFF Research Database (Denmark)

    Tweed, C. J.; Hansen, Niels; Ralph, B.

    1983-01-01

    A study of the two-dimensional and three-dimensional grain size distributions before and after grain growth treatments has been made in samples having a range of oxide contents. In order to collect statistically useful amounts of data, an automatic image analyzer was used and the resulting data w...

  4. New 3DXRD results on recrystallization and grain growth

    DEFF Research Database (Denmark)

    Juul Jensen, Dorte; West, Stine; Poulsen, Stefan Othmar;

    2012-01-01

    New in-situ 3DXRD results obtained since the last Rex&GG conference are presented and discussed. This includes: Documentation of the formation of nuclei with new orientations, determination of apparent activation energies for individual bulk grains during recrystallization and evolution in the 3D...... microstructure during grain growth...

  5. Process for preparing fine-grain metal carbide powder

    Science.gov (United States)

    Kennedy, C.R.; Jeffers, F.P.

    Fine-grain metal carbide powder suitable for use in the fabrication of heat resistant products is prepared by coating bituminous pitch on SiO/sub 2/ or Ta/sub 2/O/sub 5/ particles, heating the coated particles to convert the bituminous pitch to coke, and then heating the particles to a higher temperature to convert the particles to a carbide by reaction of said coke therewith.

  6. Charging and Growth of Fractal Dust Grains

    CERN Document Server

    Matthews, Lorin S

    2007-01-01

    The structure and evolution of aggregate grains formed within a plasma environment are dependent upon the charge acquired by the micron-sized dust grains during the coagulation process. The manner in which the charge is arranged on developing irregular structures can affect the fractal dimension of aggregates formed during collisions, which in turn influences the coagulation rate and size evolution of the dust within the plasma cloud. This paper presents preliminary models for the charge and size evolution of fractal aggregates immersed in a plasma environment calculated using a modification to the orbital-motion-limited (OML) theory. Primary electron and ion currents incident on points on the aggregate surface are determined using a line-of-sight (LOS) approximation: only those electron or ion trajectories which are not blocked by another grain within the aggregate contribute to the charging current. Using a self-consistent iterative approach, the equilibrium charge and dipole moment are calculated for the d...

  7. Recrystallization and grain growth of nanocomposite Ti-B-N coatings

    Energy Technology Data Exchange (ETDEWEB)

    Mayrhofer, P.H.; Willmann, H.; Mitterer, C

    2003-09-01

    Nanocomposite Ti-B-N coatings with different chemical composition were prepared by non-reactive co-sputtering of a segmented TiN-TiB{sub 2} target. The coatings investigated are primarily composed of nanocrystalline TiN and TiB{sub 2} phases. Increasing boron content results in a decreasing grain size from approximately 6 to 2 nm. During a thermal treatment of such coatings solely recovery and recrystallization with subsequent grain growth would appear, since the two phases are in thermodynamic equilibrium. Differential scanning calorimetry (DSC) and X-ray diffraction analysis were used to investigate the recrystallization behavior and subsequent grain growth of the nanocomposite Ti-B-N coatings. On heating the coating samples, which were removed chemically from their low alloyed steel substrates, an exothermal peak appeared during the DSC measurements indicating grain growth. From the onset temperature of this peak the recrystallization temperature was found which increases with increasing boron content from 1032 to 1070 deg. C. Activation energies for grain growth are obtained from Kissinger plots and yield values decreasing from 7.9 to 4.4 eV with increasing boron content. After heat treatment up to 1400 deg. C during the DSC measurements the coatings showed grain sizes within the range of 15-30 nm. It was found that the highest recrystallization temperature does not imply the highest activation energy for grain growth.

  8. Effects of Four Pesticides on Grain Growth Parameters of Rice

    Institute of Scientific and Technical Information of China (English)

    WU Jin-cai; DONG Bo; LI Dong-hu; QIU Hui-min; YANG Guo-qing

    2004-01-01

    Effect of four commonly used pesticides, triadlmefon, jingganmycin, triazoplos and imidacloprid, on grain growth parameters was examined using a growth equation in the present paper. Two hundreds of spikes, not damaged by pests were simultaneously marked per plot during the heading stage of rice. Rice plants were sprayed at 1 d after marking.Thereafter, 20 spikes were sampled at 4 d intervals and dried in an oven. Then, 10 superior and inferior grains were picked from each spike, and brown rice was weighed after shelling, respectively. First, second and third order derivates were deduced from the following grain growth formula:W=K/1+ea-bt , where W was the weight of 100 grains brown rice at time t; K was maximum of grain growth; a and b were parameters of the formula. The parameters were calculated as following:R0=Kbea/ (1 + ea)2 ,△ t=t2-t1,GT=bk/4(t2-t1)=Vmax(t2-t1),Vmax=bk/4Where R0, △t, GT and Vmax were initial growth power, active growth stage, accumulative weight of dried content during △ t and maximum growth rate, respectively. The result showed that GT and K of superior grain following 22.5 and 45 ga.i. ha-1 of imidacloprid sprays were significantly reduced, and △t was significantly decreased for 112.5 and 225ga.i. ha-1 jingganmycin treatments. In addition, the high dose of imidacloprid significantly reduced the weight of 1 000 rice grains by 9.77%. However, there was no significant difference for the weight of 1 000 grains between the high dose of jingganmycin and thecontrol, indicating that effective duration of jingganmycin on grain filling was shorterthan that of imidacloprid.

  9. Dynamic Demonstration of Ceramic Grain Growth in Three Dimensions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Microstructural evolutions of ceramic grain growth we re dynamically demonstrated with 3D graphical display techniques. Based on the p rinciples of grain growth in ceramics, the data of coordination in different ato ms were calculated with Monte-Carlo method at atomistic scale. Realistic images in three-dimension were displayed onto two-dimension monitor by projection, i llumination and atomization, using Visual C++ and OpenGL languages. Different small spheres were used to model different kind of atoms,...

  10. Grain growth of cast-multicrystalline silicon grown from small randomly oriented seed crystal

    Science.gov (United States)

    Prakash, Ronit R.; Sekiguchi, Takashi; Jiptner, Karolin; Miyamura, Yoshiji; Chen, Jun; Harada, Hirofumi; Kakimoto, Koichi

    2014-09-01

    Multicrystalline silicon was grown from seeds with small grains of random orientation and the growth mechanism was studied with respect to grain size, shape, boundary character and orientation. The average grain size perpendicular to growth direction increased steadily initially, became constant and then increased steadily again. Grain size parallel to growth direction increased rapidly with growth due to grain elongation in the growth direction. Grain shape with respect to growth direction changed from spherical to columnar with growth. Initially non-CSL grain boundary fraction was very high but decreased with growth as the Σ3 grain boundary fraction increased. A simple model was proposed to explain the results.

  11. Studies of methods to restrict the grain growth of nanocrystalline metal oxides

    CERN Document Server

    Al-Angari, Y

    2002-01-01

    There is considerable interest in nanocrystalline materials. This thesis is concerned with nanocrystalline oxides and the development of methods to prevent their grain growth on heating. This growth, which is evident at temperatures as low as 400 deg C, presents a serious problem in the study and applications of nanocrystalline oxides. The systems that were studied were nanocrystalline magnesium oxide, zirconium oxide, cerium oxide and tin oxide. The methods of preventing grain growth included the encapsulation of the oxide in the pores of porous silica, mixing with nanocrystals of alumina and treating the surface with a silanising agent, hexamethyldisilazane. All the methods employed showed some effect on reducing the grain growth. Encapsulation in the pores of silica was effective, however it proved difficult to get large amounts of the oxides into the pores. A more efficient method of preparing large samples was the incorporation of alumina, which was achieved by a sol-gel process. An alkoxide of the targe...

  12. Inhibition effect of phosphate on the crystal grain growth of nanosized titania

    Institute of Scientific and Technical Information of China (English)

    FENG Xiaohui; LIE Jingze; LI Ping; ZHANG Yanfeng; WEI Yu

    2009-01-01

    The inhibitory effect of phosphate on the crystal grain growth of nanosized titania during high temperature calcination was investigated. Nanosized titanium dioxide powders prepared by hydrolysis of titanium tetrachloride were soaked in phosphate solutions with different con-centrations. The obtained powders calcined at various temperatures were characterized by X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), and X-ray photoelectronic spectroscopy (XPS). The grain size of the samples without phosphate treatment in-creased quickly when calcined at high temperatures, while the grain size of the samples with phosphate modification increased slowly when calcined at the same temperature. This phenomenon implies that phosphate treatment plays an important role in inhibiting the crystal grain growth of titania. The possible mechanism of the inhibition effect of phosphate on titania is discussed.

  13. EFFECT OF SOME PLANT GROWTH REGULATORS WITH RETARDING ACTIVITY ON SPRING PEA FOR GRAIN

    Directory of Open Access Journals (Sweden)

    Tsenka ZHELYAZKOVA

    2012-12-01

    Full Text Available A field experiment was conducted at Trakia University - Stara Zagora to establish the effect of some growth retardants on morphological and productive parameters in spring pea for grain variety Bogatir. Three combined preparations: Trisalvit (phenylphthalamic acid + chlorocholine chloride + chlorophenoxyacetic acid +salicylic acid at doses of 300 and 400 сmз*ha-1; SM-21 (phenylphthalamic acid + chlorocholine chloride at doses of 300 and 400 сmз*ha-1 and PNSA-44 (phenylphthalamic acid + naphthaleneacetic acid + chlorophenoxyacetic acid at doses of 200 and 300 сmз*ha-1 were applied in the early growth phase of the plant up to a height of 15-20 cm. The study showed that the greatest reduction in the stem height (by 12.8% compared to untreated plants was achieved by applying SM-21 (400 сmз*ha-1. The application of growth regulators Trisalvit and SM-21 had no appreciable effect on the production of spring pea grain. Maximum values of yield structure components (number of pods and grain per plant, grain mass per plant and mass of 1000 grain and the yield were obtained after application of PNSA-44 (300 сmз*ha-1 - up to 5.6% (117.2 kg*ha-1 more grain than the control. The investigation of the influence of tested factors (retardant, dose and year demonstrated that the conditions of the year as a factor had the strongest effect on plant height and grain yield.

  14. Supplying materials needed for grain growth characterizations of nano-grained UO2

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Kun [Argonne National Lab. (ANL), Argonne, IL (United States); Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Yun, Di [Argonne National Lab. (ANL), Argonne, IL (United States); Jamison, Laura M. [Argonne National Lab. (ANL), Argonne, IL (United States); Lian, Jie [Rensselaer Polytechnic Inst., Troy, NY (United States); Yao, Tiankei [Rensselaer Polytechnic Inst., Troy, NY (United States)

    2015-09-30

    This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL) and aims at providing experimental data for the validation of the mesoscale simulation code MARMOT. MARMOT is a mesoscale multiphysics code that predicts the coevolution of microstructure and properties within reactor fuel during its lifetime in the reactor. It is an important component of the Moose-Bison-Marmot (MBM) code suite that has been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. In order to ensure the accuracy of the microstructure based materials models being developed within the MARMOT code, extensive validation efforts must be carried out. In this report, we summarize our preliminary synchrotron radiation experiments at APS to determine the grain size of nanograin UO2. The methodology and experimental setup developed in this experiment can directly apply to the proposed in-situ grain growth measurements. The investigation of the grain growth kinetics was conducted based on isothermal annealing and grain growth characterization as functions of duration and temperature. The kinetic parameters such as activation energy for grain growth for UO2 with different stoichiometry are obtained and compared with molecular dynamics (MD) simulations.

  15. Kinetics of Grain Growth in 718 Ni-Base Superalloy

    Directory of Open Access Journals (Sweden)

    Huda Z.

    2014-10-01

    Full Text Available The Haynes® 718 Ni-base superalloy has been investigated by use of modern material characterization, metallographic and heat treatment equipment. Grain growth annealing experiments at temperatures in the range of 1050 – 1200 oC (1323–1473K for time durations in the range of 20 min-22h have been conducted. The kinetic equations and an Arrhenius-type equation have been applied to compute the grain-growth exponent n and the activation energy for grain growth, Qg, for the investigated alloy. The grain growth exponent, n, was computed to be in the range of 0.066-0.206; and the n values have been critically discussed in relation to the literature. The activation energy for grain growth, Qg, for the investigated alloy has been computed to be around 440 kJ/mol; and the Qg data for the investigated alloy has been compared with other metals and alloys and ceramics; and critically analyzed in relation to our results.

  16. Triangular graphene grain growth on cube-tectured Cu substrates.

    Energy Technology Data Exchange (ETDEWEB)

    Liu, J.; Wu, J.; Edwards, C. M.; Berrie, C. L.; Moore, D.; Chen, Z.; Maroni, V. A.; Paranthaman, M. P.; Goyal, A. (Materials Science Division); (Univ. Kansas); (Oak Ridge Nat. Lab.)

    2011-10-21

    The growth of graphene has been carried out on cube-textured (100) oriented Cu (CTO-Cu) foils using chemical vapor deposition (CVD). Well-aligned triangular grains self-assembled on CTO-Cu during CVD heating in flowing hydrogen. The nucleation of triangular graphene grains has been confirmed. This demonstrates that the shape and possible alignment of the graphene grains can potentially be tuned by changing the properties of the substrate, which should ultimately lead to improved electrical properties of the graphene. This type of graphene nucleation and alignment is novel and has not been observed in previous studies on other copper foil samples.

  17. Recrystallization and Grain Growth of 316L Stainless Steel Wires

    Science.gov (United States)

    Zhao, Xiuyun; Liu, Yong; Wang, Yan; Feng, Ping; Tang, Huiping

    2014-07-01

    Recrystallization and grain growth behaviors of 316L stainless steel wires with a diameter of 12 µm were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction techniques. Heavily cold-drawn wires were isothermally held at temperatures from 1073 K to 1223 K (800 °C to 950 °C) for various holding times. Optical microscopy and TEM observations showed that recrystallization grains have irregular shape and that twins exist. The texture formed during drawing and annealing processes of the wires, as measured by X-ray methods, showed a fiber texture approximated by a and a component. The value of the grain growth exponent n was calculated, and the kinetic rates were plotted using the Arrhenius equation. Results show that the activation energy of the grain growth for 316L stainless steel wire was determined to be 407 kJ/mol, which was much higher than that of the bulk 316L stainless steel. The small wire diameter and the existence of texture played important roles in the increase of the activation energy for grain growth of the wire.

  18. Yttria-Ceria stabilized tetragonal zirconia polycrystals: Sintering, grain growth and grain boundary segregation

    NARCIS (Netherlands)

    Boutz, M.M.R.; Boutz, M.M.R.; Winnubst, Aloysius J.A.; Burggraaf, Anthonie; Burggraaf, A.J.

    1994-01-01

    An analysis is presented of grain growth and densification of yttria-ceria stabilized tetragonal zirconia polycrystals (Y, Ce-TZPs) using both isothermal and non-isothermal techniques. The characteristics of Y, Ce-TZPs are compared to those of Y-TZP and Ce-TZP and the effect of increasing ceria

  19. Monte Carlo grain growth modeling with local temperature gradients

    Science.gov (United States)

    Tan, Y.; Maniatty, A. M.; Zheng, C.; Wen, J. T.

    2017-09-01

    This work investigated the development of a Monte Carlo (MC) simulation approach to modeling grain growth in the presence of non-uniform temperature field that may vary with time. We first scale the MC model to physical growth processes by fitting experimental data. Based on the scaling relationship, we derive a grid site selection probability (SSP) function to consider the effect of a spatially varying temperature field. The SSP function is based on the differential MC step, which allows it to naturally consider time varying temperature fields too. We verify the model and compare the predictions to other existing formulations (Godfrey and Martin 1995 Phil. Mag. A 72 737-49 Radhakrishnan and Zacharia 1995 Metall. Mater. Trans. A 26 2123-30) in simple two-dimensional cases with only spatially varying temperature fields, where the predicted grain growth in regions of constant temperature are expected to be the same as for the isothermal case. We also test the model in a more realistic three-dimensional case with a temperature field varying in both space and time, modeling grain growth in the heat affected zone of a weld. We believe the newly proposed approach is promising for modeling grain growth in material manufacturing processes that involves time-dependent local temperature gradient.

  20. Giant secondary grain growth in Cu films on sapphire

    Directory of Open Access Journals (Sweden)

    David L. Miller

    2013-08-01

    Full Text Available Single crystal metal films on insulating substrates are attractive for microelectronics and other applications, but they are difficult to achieve on macroscopic length scales. The conventional approach to obtaining such films is epitaxial growth at high temperature using slow deposition in ultrahigh vacuum conditions. Here we describe a different approach that is both simpler to implement and produces superior results: sputter deposition at modest temperatures followed by annealing to induce secondary grain growth. We show that polycrystalline as-deposited Cu on α-Al2O3(0001 can be transformed into Cu(111 with centimeter-sized grains. Employing optical microscopy, x-ray diffraction, and electron backscatter diffraction to characterize the films before and after annealing, we find a particular as-deposited grain structure that promotes the growth of giant grains upon annealing. To demonstrate one potential application of such films, we grow graphene by chemical vapor deposition on wafers of annealed Cu and obtain epitaxial graphene grains of 0.2 mm diameter.

  1. Grain boundary cavity growth under applied stress and internal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mancuso, J.F.

    1977-08-01

    The growth of grain boundary cavities under applied stress and internal gas pressure was investigated. Methane gas filled cavities were produced by the C + 4H reversible CH4 reaction in the grain boundaries of type 270 nickel by hydrogen charging in an autoclave at 500/sup 0/C with a hydrogen pressure of either 3.4 or 14.5 MPa. Intergranular fracture of nickel was achieved at a charging temperature of 300/sup 0/C and 10.3 MPa hydrogen pressure. Cavities on the grain boundaries were observed in the scanning electron microscope after fracture. Photomicrographs of the cavities were produced in stereo pairs which were analyzed so as to correct for perspective distortion and also to determine the orientational dependence of cavity growth under an applied tensile stress.

  2. Study on the Effect between Dynamics of MgO Grain Growth and Additive of Y2O3

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, samples of CaO-riched MgO-CaO added with Y2O3 were prepared and the growth rate of MgO grains were investigated, and the calculation of the grain growth active energy at different temperatures was done for the high performance anti-hydration CaO-riched MgO-CaO clinker. It is of significance for decreasing the synthetic temperature in industry production.

  3. Multi-phase-field study of the effects of anisotropic grain-boundary properties on polycrystalline grain growth

    Science.gov (United States)

    Miyoshi, Eisuke; Takaki, Tomohiro

    2017-09-01

    Numerical studies of the effects of anisotropic (misorientation-dependent) grain-boundary energy and mobility on polycrystalline grain growth have been carried out for decades. However, conclusive knowledge has yet to be obtained even for the simplest two-dimensional case, which is mainly due to limitations in the computational accuracy of the grain-growth models and computer resources that have been employed to date. Our study attempts to address these problems by utilizing a higher-order multi-phase-field (MPF) model, which was developed to accurately simulate grain growth with anisotropic grain-boundary properties. In addition, we also employ general-purpose computing on graphics processing units to accelerate MPF grain-growth simulations. Through a series of simulations of anisotropic grain growth, we succeeded in confirming that both the anisotropies in grain-boundary energy and mobility affect the morphology formed during grain growth. On the other hand, we found the grain growth kinetics in anisotropic systems to follow parabolic law similar to isotropic growth, but only after an initial transient period.

  4. Modeling nano-scale grain growth of intermetallics

    Indian Academy of Sciences (India)

    Mohsen Kazeminezhad

    2009-02-01

    The Monte Carlo simulation is utilized to model the nano-scale grain growth of two nanocrystalline materials, Pd81Zr19 and RuAl. In this regard, the relationship between the real time and the time unit of simulation, i.e. Monte Carlo step (MCS), is determined. The results of modeling show that with increasing time of heating, the grain sizes of both nano-crystalline materials increased as in the case of conventional materials. Moreover, it is found that for both nano-crystalline materials the relationship between the real time and MCS is in power law form, which is linear for the conventional materials.

  5. Sintering boron carbide ceramics without grain growth by plastic deformation as the dominant densification mechanism

    Science.gov (United States)

    Ji, Wei; Rehman, Sahibzada Shakir; Wang, Weimin; Wang, Hao; Wang, Yucheng; Zhang, Jinyong; Zhang, Fan; Fu, Zhengyi

    2015-10-01

    A new ceramic sintering approach employing plastic deformation as the dominant mechanism is proposed, at low temperature close to the onset point of grain growth and under high pressure. Based on this route, fully dense boron carbide without grain growth can be prepared at 1,675-1,700 °C and under pressure of (≥) 80 MPa in 5 minutes. The dense boron carbide shows excellent mechanical properties, including Vickers hardness of 37.8 GPa, flexural strength of 445.3 MPa and fracture toughness of 4.7 MPa•m0.5. Such a process should also facilitate the cost-effective preparation of other advanced ceramics for practical applications.

  6. Sintering boron carbide ceramics without grain growth by plastic deformation as the dominant densification mechanism.

    Science.gov (United States)

    Ji, Wei; Rehman, Sahibzada Shakir; Wang, Weimin; Wang, Hao; Wang, Yucheng; Zhang, Jinyong; Zhang, Fan; Fu, Zhengyi

    2015-10-27

    A new ceramic sintering approach employing plastic deformation as the dominant mechanism is proposed, at low temperature close to the onset point of grain growth and under high pressure. Based on this route, fully dense boron carbide without grain growth can be prepared at 1,675-1,700 °C and under pressure of (≥) 80 MPa in 5 minutes. The dense boron carbide shows excellent mechanical properties, including Vickers hardness of 37.8 GPa, flexural strength of 445.3 MPa and fracture toughness of 4.7 MPa•m(0.5). Such a process should also facilitate the cost-effective preparation of other advanced ceramics for practical applications.

  7. Simulation of grain growth in nanocrystalline nickel induced by ion irradiation

    CERN Document Server

    Voegeli, W; Hahn, H

    2003-01-01

    Molecular dynamics simulations of 5 keV cascades in nanocrystalline nickel with grain sizes of 5 and 10 nm are presented. If the spike volume is exceeding the grain size or overlapping the grain boundary (GB) area we observe ion-beam induced grain growth for both grain sizes. In contrast cascades located in the grain volume lead to the formation of vacancies and interstitials, where the latter are mostly accommodated by the GBs upon annealing. Finally, we show that ion-beam induced grain growth is a direct result of recrystallisation of the thermal spike and therefore inherently different to grain growth observed in long time thermal annealing simulations.

  8. Recrystallization and grain growth in NiAl

    Science.gov (United States)

    Haff, G. R.; Schulson, E. M.

    1982-01-01

    Aluminide intermetallics, because of their strength, microstructural stability, and oxidation resistance at elevated temperatures, represent potential structural materials for use in advanced energy conversion systems. This inherent potential of the intermetallics can currently not be realized in connection with the general brittleness of the materials under ambient conditions. It is pointed out, however, that brittleness is not an inherent characteristic. Single crystals are ductile and polycrystals may be, too, if their grains are fine enough. The present investigation is concerned with an approach for reducing material brittleness, taking into account thermal-mechanically induced grain refinement in NiAl, a B2 aluminide which melts at 1638 C and which retains complete order to its melting point. Attention is given to the kinetics of recrystallization and grain growth of warm-worked, nickel-rich material.

  9. Constitutive modeling of stress-driven grain growth in nanocrystalline metals

    KAUST Repository

    Gürses, Ercan

    2013-02-08

    In this work, we present a variational multiscale model for grain growth in face-centered cubic nanocrystalline (nc) metals. In particular, grain-growth-induced stress softening and the resulting relaxation phenomena are addressed. The behavior of the polycrystal is described by a conventional Taylor-type averaging scheme in which the grains are treated as two-phase composites consisting of a grain interior phase and a grain boundary-affected zone. Furthermore, a grain-growth law that captures the experimentally observed characteristics of the grain coarsening phenomena is proposed. To this end, the grain size is not taken as constant and varies according to the proposed stress-driven growth law. Several parametric studies are conducted to emphasize the influence of the grain-growth rule on the overall macroscopic response. Finally, the model is shown to provide a good description of the experimentally observed grain-growth-induced relaxation in nc-copper. © 2013 IOP Publishing Ltd.

  10. UO2 Grain Growth: Developing Phase Field Models for Pore Dragging, Solute Dragging and Anisotropic Grain Boundary Energies

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, K.; Tonks, M.; Zhang, Y.; Biner, B.

    2016-09-28

    A detailed phase field model for the effect of pore drag on grain growth kinetics was implemented in MARMOT. The model takes into consideration both the curvature-driven grain boundary motion and pore migration by surface diffusion. As such, the model accounts for the interaction between pore and grain boundary kinetics, which tends to retard the grain growth process. Our 2D and 3D simulations demonstrate that the model capture all possible pore-grain boundary interactions proposed in theoretical models. For high enough surface mobility, the pores move along with the migrating boundary as a quasi-rigid-body, albeit hindering its migration rate compared to the pore-free case. For less mobile pores, the migrating boundary can separate from the pores. For the pore-controlled grain growth kinetics, the model predicts a strong dependence of the growth rate on the number of pores, pore size, and surface diffusivity in agreement with theroretical models. An evolution equation for the grain size that includes these parameters was derived and showed to agree well with numerical solution. It shows a smooth transition from boundary-controlled kinetics to pore-controlled kinetics as the surface diffusivity decreases or the number of pores or their size increases. This equation can be utilized in BISON to give accurate estimate for the grain size evolution. This will be accomplished in the near future. The effect of solute drag and anisotropy of grain boundary on grain growth will be investigated in future studies.

  11. Preparation of high-quality HTS rings for application in the magnetic bearing of cryotanks and pinning in grain boundaries

    Science.gov (United States)

    Bringmann, B.; Walter, H.; Jooss, Ch.; Leenders, A.; Freyhardt, H. C.

    2002-08-01

    Seeded melt growth of YBCO high-temperature superconductors is one of the most promising preparation techniques to obtain high-quality HTS tiles for application, e.g. in magnetic bearings. Semi-finished HTSL products of complex shapes have to be developed by different seeding and multi-seeding techniques. To obtain large hollow cylinders designed for application in the magnetic bearing of a cryotank a modified multi-seeded melt growth (MSMG) process was employed. This cryotank will be mounted for testing in a vehicle of a major German car manufacturer. The MSMG process introduces grain boundaries into the HTS tiles. For transport current investigations of [0 0 1]-tilt grain boundaries in melt textured YBCO a series of MSMG bicrystals have been prepared. They exhibit a dependence of the critical current density on misorientation angle which is much weaker than the one observed in thin-film bicrystals. The bulk samples have dimensions larger than the magnetic penetration depth along the grain boundary. Thus, flux pinning has to be taken into account. Different contributions to the longitudinal pinning force have to be considered: vortices at grain boundaries can be pinned by magnetic interaction with Abrikosov vortices in the banks, by defects in the grain boundary itself or by defects which are located next to the grain boundary.

  12. RESTRAINTS ON THIN SECTION ANALYSIS OF GRAIN GROWTH IN UNSTRAINED POLYCRYSTALLINE ICE

    OpenAIRE

    Gow, A.

    1987-01-01

    Tests were performed at -1°C to evaluate the effects of a free surface and the thickness dimensions of thin sections on the growth of grains in fine-grained, pore-rich, strain-free polycrystalline ice. Results show that negligible growth of grains occurs when the mean size of grains is more than 1.5 to 2 times the section thickness. Grain growth in thicker sections was significant for the fact that grain boundary migration, leading to 3-4 fold increases in average grain size, was virtually un...

  13. Consideration of Zener drag effect by introducing a limiting radius for neighbourhood in grain growth simulation

    Science.gov (United States)

    Maazi, N.; Rouag, N.

    2002-08-01

    A model for grain growth simulation, in the presence of preferential particle distribution, is presented. The model predicts two grain size limits due to second-phase particles. Less than the maximal critical radius the grains will shrink. Greater than the minimal critical radius the grains will grow. Between the two limiting radii no grain growth takes place. These critical radii permit us to introduce the effect of the precipitates directly in the simulation procedure, without their assigning sites in the base matrix. In this case, all sites of the matrix are only occupied by grains. The conditions necessary for the development of secondary recrystallization in textured materials such as Fe-3%Si are, first, the stagnation of normal grain growth, second, the presence of special boundaries around the secondary grains. The grain growth simulation is performed until the grain structure was pinned, i.e. when boundaries become pinned.

  14. Process for preparing fine grain silicon carbide powder

    Science.gov (United States)

    Wei, G.C.

    Method of producing fine-grain silicon carbide powder comprises combining methyltrimethoxysilane with a solution of phenolic resin, acetone and water or sugar and water, gelling the resulting mixture, and then drying and heating the obtained gel.

  15. Optimization Algorithm in the Simulation of Ceramic Grain Growth

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Optimization Algorithm was developed for the simula ti on of ceramic grain growth at atomistic scale. Based on the coordination informa tion of different atoms, a structure of trident tree was applied to save large q uantities data, so as to solve the problems of large data information and long r unning time. For every atom a binary tree was firstly formed according to the X coordination of atom. If the values of X coordination were the same, the middle sub-tree of first layer formed then a binary tree ac...

  16. Grain growth of ε-iron: Implications to grain size and its evolution in the Earth's inner core

    Science.gov (United States)

    Yamazaki, Daisuke; Tsujino, Noriyoshi; Yoneda, Akira; Ito, Eiji; Yoshino, Takashi; Tange, Yoshinori; Higo, Yuji

    2017-02-01

    Knowledge of grain growth rate of ε-iron can put constraint on estimation of the grain size in the inner core. We determined grain growth rate of ε-iron at ∼55 GPa and 1200-1500 K by means of in-situ X-ray diffraction observation to be Gn - G0n = kt, where G (m) is the grain size at time t (s), G0 (m) is the initial grain size, n is growth exponent (fixed to 2) and k is the growth constant expressed as k =k0 exp ⁡ (-H* / RT) with log k0 (mn /s) = - 5.8 (± 2.4) and activation enthalpy H* = 221 (± 61) kJ /mol, and R is the gas constant and T is the absolute temperature. Extrapolation of the grain growth law of ε-iron to the inner core conditions suggests that the grain size in the inner core is in a range from several hundred meters to several kilometers, which is intermediate among the previous estimations, and hence the dominant deformation mechanism is considered to be Harper-Dorn creep rather than diffusion creep as pointed out by the previous work. This indicates the relatively uniform viscosity in the entire inner core.

  17. Effects of seed orientation on the growth behavior of single grain REBCO bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Gyoun [Korea Polytechnic University, Siheung (Korea, Republic of)

    2017-06-15

    This study presents a simple method to control the seed orientation which leads to the various growth characteristics of a single grain REBCO (RE: rare-earth elements) bulk superconductors. Seed orientation was varied systematically from c-axis to a-axis with every 30 degree rotation around b-axis. Orientations of a REBCO single grain was successfully controlled by placing the seed with various angles on the prismatic indent prepared on the surface of REBCO powder compacts. Growth pattern was changed from cubic to rectangular when the seed orientation normal to compact surface was varied from c-axis to a-axis. Macroscopic shape change has been explained by the variation of the wetting angle of un-reacted melt depending on the interface energy between YBa2Cu3O7-y (Y123) grain and melt. Higher magnetic levitation force was obtained for the specimen prepared using tilted seed with an angle of 30 degree rotation around b-axis.

  18. Influence of Grain Growth Inhibitors and Powder Size on the Properties of Ultrafine and Nanostructured Cemented Carbides Sintered in Hydrogen

    Directory of Open Access Journals (Sweden)

    Tamara Aleksandrov Fabijanić

    2016-08-01

    Full Text Available The influence of grain growth inhibitors and powder size on the microstructure and mechanical properties of ultrafine and nanostructured cemented carbides was researched. Three different WC powders, with an addition of different type and content of grain growth inhibitors GGIs, VC and Cr3C2 and with dBET grain sizes in the range from 95 to 150 nm were selected as starting powders. Four different mixtures with 6 and 9 wt. % Co were prepared. The consolidated samples are characterized by different microstructural and mechanical properties with respect to the characteristics of starting powders. Increased sintering temperatures led to microstructural irregularities in the form of a discontinuous WC growth, carbide agglomerates and abnormal grain growth as a consequence of coalescence via grain boundary elimination. The addition of 0.45% Cr3C2 contributed to microstructure homogeneity, reduced discontinuous and continuous grain growth, and increased Vickers hardness by approximately 70 HV and fracture toughness by approximately 0.15 MN/m3/2. The reduction of the starting powder to a real nanosize of 95 nm resulted in lower densities, and significant hardness increase, with a simultaneously small increase in fracture toughness. The consolidation of real nanopowders (dBET < 100 nm solely by conventional sintering in hydrogen without isostatic pressing is not preferred.

  19. Grain growth in thoria and thoria-base fuel pellets (LWBR development program)

    Energy Technology Data Exchange (ETDEWEB)

    Smid, R.J.

    1976-01-01

    The kinetics of grain growth in ThO/sub 2/-base sintered compacts were investigated to determine the cause of a nonuniform microstructural cross section. It was concluded that trace impurities which inhibit continuous grain growth at the pellet interior were removed by vaporization at the pellet exterior. This resulted in relatively normal grain growth at the pellet surface and discontinuous grain growth at the pellet interior. Calcining the starting ThO/sub 2/ powder to a slightly higher temperature removed inhibiting impurities but also decreased the driving force for grain growth by reducing the surface area of the powder. Mixing high and low temperature calcined ThO/sub 2/ resulted in improved grain growth. Increased oxygen partial pressure and temperature during sintering increased grain boundary mobility in spite of the inhibiting impurity. The specific inhibiting impurity was not isolated during this investigation.

  20. On grain growth kinetics in two-phase polycrystalline materials through Monte Carlo simulation

    Indian Academy of Sciences (India)

    K R Phaneesh; Anirudh Bhat; Gautam Mukherjee; K T Kashyap

    2013-08-01

    Monte Carlo Potts model simulation was carried out on a 2D square lattice for various surface fractions of second phase particles for over 50,000 iterations. The observations are in good agreement with known theoretical and experimental results with respect to both growth kinetics as well as grain size distribution. Further, the average grain size and the largest grain size were computed for various surface fractions which have indicated normal grain growth and microstructure homogeneity. The surface fraction of the second phase particles interacting with the grain boundaries (), hitherto not computed through the simulation route, is shown to vary inversely as the average grain size due to Zener pinning.

  1. Grain growth of Al-4Cu-Mg alloy during isothermal heat treatment

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure of an Al-4Cu-Mg alloy during isothermal heat treatment in the Strain Induced Melt Activation (SIMA)process was investigated and the kinetics of grain growth was analyzed. The grain growth during isothermal heat treatment of the Al4Cu-Mg alloy coincided with the Ostwald ripening theory. During isothermal heat treatment, both grain shape and the high volume fraction of solid phase have significant effects on grain growth. Therefore, a new grain growth model based on the Ostwald ripening theory was proposed taking into consideration the grain shape and the volume fraction of solid phase. By comparing the calculated results with the experimental results, it was confirmed that the present model could be applied to grain growth during isothermal heat treatment of the Al-4Cu-Mg alloy in the SIMA process.

  2. Derivation of Hillert-type 3D grain growth rate model with topological considerations and discussion on its grain size parameter

    Institute of Scientific and Technical Information of China (English)

    Guoquan Liu; Haibo Yu; Xiaoyan Song; Xiangge Qin; Chao Wang

    2004-01-01

    A Hillert-type three-dimensional grain growth rate model was derived through the grain topology-size correlation model,combined with a topology-dependent grain growth rate equation in three dimensions. It shows clearly that the Hillert-type 3D grain growth rate model may also be described with topology considerations of microstructure. The size parameter bearing in the model is further discussed both according to the derived model and in another approach with the aid of quantitative relationship between the grain size and the integral mean curvature over grain surface. Both approaches successfully demonstrate that, if the concerned grains can be well approximated by a space-filling convex polyhedra in shape, the grain size parameter bearing in the Hillert-type 3D grain growth model should be a parameter proportional to the mean grain tangent radius.

  3. Phenomenological description of grain growth stagnation for nanocrystalline films and powders

    Energy Technology Data Exchange (ETDEWEB)

    Dannenberg, R.; Stach, E.A.; Groza, J.R.

    2000-08-24

    At fixed hold temperatures, grain growth usually stagnates indefinitely after sufficiently long hold times. The change in the growth behavior can be very abrupt, resulting in a sudden plateau in plots of grain size versus time at fixed temperature. Standard grain growth laws do not formally predict the rapid onset of growth stagnation, merely a slow down of grain growth to imperceptible rates. Therefore, the grain size in the plateau regions for long hold times is typically not in agreement with that predicted with kinetic variables derived from the size versus time curves for short hold times where there is pronounced curvature. Standard laws lead to endpoint grain sizes with strong dependences on the hold times. The experimental observation in many cases is a nearly linear temperature dependence that is independent of the hold times after a sufficient duration. Additionally, the growth process may restart from a stagnated state with sufficient temperature increases, where again, the stagnated grain size temperature dependence is linear. For growth laws including size dependent opposing forces, endpoint grain sizes are predicted to be either independent of temperature, or exponentially temperature dependent with thermodynamic reversibility, the latter an impossibility. We derive, heuristically, a stagnation force, phenomenologically incorporating these observations: a near linear temperature dependence of endpoint grain sizes, and irreversible growth. This description reduces to standard laws commonly used for data fitting, and leads to a normal grain size distribution. Other laws are discussed and compared. Fits to size versus time data are successfully made.

  4. Evaluation of brewers' spent grain as a novel media for yeast growth.

    Science.gov (United States)

    Cooray, Sachindra T; Lee, Jaslyn J L; Chen, Wei Ning

    2017-12-01

    Brewers' spent grain (BSG) is a by-product generated from the beer manufacturing industry, which is extremely rich in protein and fiber. Here we use low cost BSG as the raw material for the production of a novel growth media, through a bioconversion process utilizing a food grade fungi to hydrolyze BSG. The novel fermentation media was tested on the yeast Rhodosporidium toruloides, a natural yeast producing carotenoid. The yeast growth was analysed using the growth curve and the production of intracellular fatty acids and carotenoids. Untargeted GCMS based metabolomics was used to analyse the constituents of the different growth media, followed by multivariate data analysis. Growth media prepared using fermented BSG was found to be able to support the growth in R. toruloides (21.4 mg/ml) in comparable levels to YPD media (24.7 mg/ml). Therefore, the fermented BSG media was able to fulfill the requirement as a nitrogen source for R. toruloides growth. This media was able to sustain normal metabolomics activity in yeast, as indicated by the level of fatty acid and carotenoid production. This can be explained by the fact that, in the fermented BSG media metabolites and amino acids were found to be higher than in the unfermented media, and close to the levels in YPD media. Taken together, our study provided evidence of a growth media for yeast using BSG. This should have potential in replacing components in the current yeast culture media in a sustainable and cost effective manner.

  5. The effect of electronic energy loss on irradiation-induced grain growth in nanocrystalline oxides.

    Science.gov (United States)

    Zhang, Yanwen; Aidhy, Dilpuneet S; Varga, Tamas; Moll, Sandra; Edmondson, Philip D; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N; Weber, William J

    2014-05-07

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, energetic ions deposit their energy to both atomic nuclei and electrons. Our experimental results have shown that irradiation-induced grain growth is dependent on the total energy deposited, where electronic energy loss and elastic collisions between atomic nuclei both contribute to the production of disorder and grain growth. Our atomistic simulations reveal that a high density of disorder near grain boundaries leads to locally rapid grain movement. The additive effect from both electronic excitation and atomic collision cascades on grain growth demonstrated in this work opens up new possibilities for controlling grain sizes to improve functionality of nanocrystalline materials.

  6. The Effect Of Electronic Energy Loss On Irradiation-induced Grain Growth In Nanocrystalline Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanwen; Aidhy, Dilpuneet S.; Varga, Tamas; Moll, Sandra; Edmondson, Philip D.; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N.; Weber, William J.

    2014-03-03

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, energetic ions deposit their energy to both atomic nuclei and electrons. Our experimental results have shown that irradiationinduced grain growth is dependent on the total energy deposited, where electronic energy loss and elastic collisions between atomic nuclei both contribute to the production of disorder and grain growth. Our atomistic simulations reveal that a high density of disorder near grain boundaries leads to locally rapid grain movement. The additive effect from both electronic excitation and atomic collision cascades on grain growth demonstrated in this work opens up new possibilities for controlling grain sizes to improve functionality of nanocrystalline materials.

  7. Verification of topological relationship in 2-D grain growth process by simulation

    Institute of Scientific and Technical Information of China (English)

    Chao Wang; Guoquan Liu; Ya Sun; Xiangge Qin

    2004-01-01

    Behaviors of the quasi-steady state grain size distribution and the corresponding topological relationship were investigated using the Ports Monte Carlo method to simulate the normal grain growth process. The observed quasi-steady state grain size distribution can be well fit by the Weibull function rather than the Hillert distribution. It is also found that the grain size and average number of grain sides are not linearly related. The reason that the quasi-steady state grain size distribution deviates from the Hillert distribution may contribute to the nonlinearity of the relation of the average number of grain sides with the grain size. The results also exhibit the reasonability of the relationship deduced by Mullins between the grain size distribution and the average number of grain sides.

  8. Effect of stress-induced grain growth during room temperature tensile deformation on ductility in nanocrystalline metals

    Indian Academy of Sciences (India)

    Weichang Xu; Pinqiang Dai; Xiaolei Wu

    2010-10-01

    In the present study defect-free nanocrystalline (nc) Ni–Co alloys with the Co content ranging from 2.4–59.3% (wt.%) were prepared by pulse electrodeposition. X-ray diffraction analysis shows that only a single face-centred cubic solid solution is formed for each alloy and that the grain size reduces monotonically with increasing Co content, which is consistent with transmission electron microscopy (TEM) observations. In the nc Ni–Co alloys, both the ultimate tensile strength and the elongation to failure increase as the Co content increases. 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 and/or grain rotation) during deformation more difficult. Thus, stress-induced grain growth is greatly suppressed. At the same time, shear banding plasticity instability is correspondingly delayed leading to the enhanced ductility.

  9. Phase-field model of isothermal solidification with multiple grain growth

    Institute of Scientific and Technical Information of China (English)

    Feng Li; Wang Zhi-Ping; Zhu Chang-Sheng; Lu Yang

    2009-01-01

    This paper develops a new phase-field model for equiaxed dendrite growth of multiple grains in multicomponent alloys based on the Ginzberg-Landau theory and phase-field model of a single grain. Taking Al-Cu and Al-Cu-Mg alloys for example, it couples the concentration field and simulates the dendrite growth process of multiple grains during isothermal solidification. The result of the simulation shows dendrite competitive growth of multiple grains, and is reapplied to the process of dendrite growth in practical solidification.

  10. Direct observation of 3-D grain growth in Al–0.1% Mn

    DEFF Research Database (Denmark)

    Schmidt, Søren; Olsen, Ulrik Lund; Poulsen, Henning Friis

    2008-01-01

    Grain growth in an Al-0.1% Mn sample has been measured non-destructively using a three-dimensional X-ray diffraction (3DXRD) microscope. The 3-D grain morphology as well as the crystallographic orientation was determined for 483 grains in the illuminated volume prior to annealing. After annealing...

  11. Influence of Annealing on the Grain Growth and Thermal Diffusivity of Nanostructured YSZ Thermal Barrier Coating

    Institute of Scientific and Technical Information of China (English)

    Na WANG; Chungen ZHOU; Shengkai GONG; Huibin XU

    2006-01-01

    The nanostructured zirconia coatings were deposited by atmospherically plasma spraying. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction were used to investigate the microstructure of the zirconia coatings. Thermal diffusivity values at normal temperatures have been evaluated by laser flash technique. Effect of annealing on the microstructure evolution of the zirconia coating has been performed. The grains and thermal diffusivity are increased with increasing annealing time and temperature.The grain growth is according to the GRIGC (the grain rotation induced grain coalescence) mechanism. The increase in thermal diffusivity is attributed to the grain growth and the decrease in porosity of nanostructured zirconia coatings.

  12. Strain induced grain boundary migration effects on grain growth of an austenitic stainless steel during static and metadynamic recrystallization

    Energy Technology Data Exchange (ETDEWEB)

    Paggi, A., E-mail: alpaggi@tenaris.com [Tenaris Dalmine R& D, Dalmine S.p.A., Piazza Caduti 6 Luglio 1944 n.1, 24044 Dalmine (Italy); Angella, G.; Donnini, R. [National Research Council (CNR), Institute for Energetics and Interphases (IENI), Via Roberto Cozzi 53, 20125 Milano (Italy)

    2015-09-15

    Static and metadynamic recrystallization of an AISI 304L austenitic stainless steel was investigated at 1100 °C and 10{sup −} {sup 2} s{sup −} {sup 1} strain rate. The kinetics of recrystallization was determined through double hit compression tests. Two strain levels were selected for the first compression hit: ε{sub f} = 0.15 for static recrystallization (SRX) and 0.25 for metadynamic recrystallization (MDRX). Both the as-deformed and the recrystallized microstructures were investigated through optical microscopy and electron back-scattered diffraction (EBSD) technique. During deformation, strain induced grain boundary migration appeared to be significant, producing a square-like grain boundary structure aligned along the directions of the maximum shear stresses in compression. EBSD analysis revealed to be as a fundamental technique that the dislocation density was distributed heterogeneously in the deformed grains. Grain growth driven by surface energy reduction was also investigated, finding that it was too slow to explain the experimental data. Based on microstructural results, it was concluded that saturation of the nucleation sites occurred in the first stages of recrystallization, while grain growth driven by strain induced grain boundary migration (SIGBM) dominated the subsequent stages. - Highlights: • Recrystallization behavior of a stainless steel was investigated at 1100 °C. • EBSD revealed that the dislocation density distribution was heterogeneous during deformation. • Saturation of nucleation sites occurred in the first stages of recrystallization. • Strain induced grain boundary migration (SIGBM) effects were significant. • Grain growth driven by SIGBM dominated the subsequent stages.

  13. In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel

    Institute of Scientific and Technical Information of China (English)

    Feng Liu; Guang Xu; Yu-long Zhang; Hai-jiang Hu; Lin-xin Zhou; Zheng-liang Xue

    2013-01-01

    In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100◦C for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100◦C, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the eff ect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.

  14. Grain growth in U-7Mo alloy: A combined first-principles and phase field study

    Science.gov (United States)

    Mei, Zhi-Gang; Liang, Linyun; Kim, Yeon Soo; Wiencek, Tom; O'Hare, Edward; Yacout, Abdellatif M.; Hofman, Gerard; Anitescu, Mihai

    2016-05-01

    Grain size is an important factor in controlling the swelling behavior in irradiated U-Mo dispersion fuels. Increasing the grain size in U-Mo fuel particles by heat treatment is believed to delay the fuel swelling at high fission density. In this work, a multiscale simulation approach combining first-principles calculation and phase field modeling is used to investigate the grain growth behavior in U-7Mo alloy. The density functional theory based first-principles calculations were used to predict the material properties of U-7Mo alloy. The obtained grain boundary energies were then adopted as an input parameter for mesoscale phase field simulations. The effects of annealing temperature, annealing time and initial grain structures of fuel particles on the grain growth in U-7Mo alloy were examined. The predicted grain growth rate compares well with the empirical correlation derived from experiments.

  15. 4D Study of Grain Growth in Armco Iron Using Laboratory X-ray Diffraction Contrast Tomography

    Science.gov (United States)

    Sun, J.; Lyckegaard, A.; Zhang, Y. B.; Catherine, S. A.; Patterson, B. R.; Bachmann, F.; Gueninchault, N.; Bale, H.; Holzner, C.; Lauridsen, E.; Jensen, D. Juul

    2017-07-01

    Using a novel laboratory diffraction contrast tomography (LabDCT) technique, a non-destructive 4D study was conducted to investigate the evolution in 3D of the grain structure during grain growth in an Armco iron sample. The 3D grain morphology and the crystallographic orientations of more than 300 grains were determined at three temporal states during annealing. The correlation between growth of grains and grain orientation is explored. The results demonstrate the capability of the LabDCT technique to allow detailed studies of grain growth, and thereby provide the necessary 4D experimental evidence required for further understanding of grain growth.

  16. EFFECT OF THE METHOD OF PREPARATION OF RYE GRAIN ON ITS MICROSTRUCTURE AND SAFETY INDICATORS

    Directory of Open Access Journals (Sweden)

    E. I. Ponomareva

    2014-01-01

    Full Text Available Summary. One of the main issues in the baking industry is currently the development and introduction of new products increased nutritional value. By promising area of enrichment products include the use of whole grains. Currently pressing issue is expanding the range of bakery products by applying the functional orientation of the whole grain rye. Expand the range of bread from a mixture of rye and wheat flour can be due to the use of whole grain rye. German company "Irex" developed a method of preparing a mixture of products from rye and wheat flour with the addition of acidified whole rye "Saftkorn." The experiment was conducted microstructure definition, content of toxic elements (cadmium, lead, mercury, arsenic and microbiological indicators rye "Saftkorn" and "Avanguard". The microstructure and grain safety performance prepared in different ways. The difference in the microstructure of rye "Saftсorn" (Germany and "Аvangard" (Russia. Proven that their microbiological parameters were within acceptable limits.

  17. Effect of initial variance of microstructures on grain growth under mean curvature

    Science.gov (United States)

    Baskaran, Arun; Crist, David; Lewis, Daniel

    2017-09-01

    Surface Evolver was used to simulate grain growth under motion by mean curvature starting with non-uniform microstructures. The study was conducted for different microstructures that begin evolving with an identical mean grain area and a differing value of statistical variance of the grain areas. Correlation between a microstructure’s initial variance, a geometric property of the polycrystalline network, and its growth rate in the normal regime was studied. It was observed that the microstructures evolved at different growth rates. The microstructures with the largest and smallest variances evolved with highest and lowest growth rates. The analysis was performed in the normal grain growth regime. It is observed that a direct correlation can be made between the initial variance of the microstructure and its growth rate in the normal regime. These results highlight the importance of including the grain size variance when controlling microstructure using non-uniform thermal fields.

  18. Nanoscale grain growth behaviour of CoAl intermetallic synthesized by mechanical alloying

    Indian Academy of Sciences (India)

    S N Hosseini; M H Enayati; F Karimzadeh

    2014-05-01

    Grain growth behaviour of the nanocrystalline CoAl intermetallic compound synthesized by mechanical alloying has been studied by isothermal annealing at different temperatures and durations. X-ray diffraction method was employed to investigate structural evolutions during mechanical alloying and annealing processes. The disordered CoAl phase with the grain size of about 6 nm was formed via a gradual reaction during mechanical alloying. The results of isothermal annealing showed that the grain growth behaviour can be explained by the parabolic grain growth law. The grains were at nanometric scale after isothermal annealing up to 0.7 m. The grain growth exponent remained constant above 873 K indicating that grain growth mechanism does not change at high temperatures. The calculated activation energy indicated that the grain growth mechanism in the disordered CoAl phase at high temperatures was diffusing Co and Al atoms in two separate sublattices. Furthermore, an equation has been suggested to describe the grain growth kinetics of nanocrystalline CoAl under isothermal annealing at temperatures above 873 K (/m ≥ 0.5).

  19. Grain growth in calibre rolled Mg–3Al–1Zn alloy and its effect on hardness

    Directory of Open Access Journals (Sweden)

    R.L. Doiphode

    2015-12-01

    Full Text Available Calibre rolling of Mg–3Al–1Zn alloy at 300 °C led to development of fine grain size of 3 µm. Subsequent annealing, from 5 to 6000 minutes at 300–450 °C, revealed faster grain growth initially up to 60 minutes, which became sluggish on prolonged annealing. The time exponent for grain growth kinetics (n suggests bi-linear behaviour with n = 0.11 and 0.008 over these time scales. The activation energy, based on various n values, varied over wide ranges that made the understanding of the mechanisms for grain growth difficult. This problem is explained by concurrent evolution of texture and grain boundary structure. The effect of grain growth on hardness at ambient temperature was found to follow the H–P type relationship.

  20. Grain growth kinetics in liquid-phase-sintered zinc oxide-barium oxide ceramics

    Science.gov (United States)

    Yang, Sung-Chul; German, Randall M.

    1991-01-01

    Grain growth of ZnO in the presence of a liquid phase of the ZnO-BaO system has been studied for temperatures from 1300 to 1400 C. The specimens were treated in boiling water and the grains were separated by dissolving the matrix phase in an ultrasonic bath. As a consequence 3D grain size measurements were possible. Microstructural examination shows some grain coalescence with a wide range of neck size ratios and corresponding dihedral angles, however, most grains are isolated. Lognormal grain size distributions show similar shapes, indicating that the growth mechanism is invariant over this time and temperature. All regressions between G exp n and time for n = 2 and 3 proved statistically significant. The rate constants calculated with the growth exponent set to n = 3 are on the same order of magnitude as in metallic systems. The apparent activation energy for growth is estimated between 355 and 458 kJ/mol.

  1. A Three-Dimensional Cellular Automata Model Coupling Energy and Curvature-Driven Mechanisms for Austenitic Grain Growth

    Science.gov (United States)

    Wang, Min; Zhou, Jianxin; Yin, Yajun; Nan, Hai; Zhang, Dongqiao; Tu, Zhixin

    2017-10-01

    A 3D cellular automata model is used to simulate normal austenitic grain growth in this study. The proposed model considers both the curvature- and thermodynamics-driven mechanisms of growth. The 3D grain growth kinetics shows good agreement with the Beck equation. Moreover, the growth exponent and grain size distribution calculated by the proposed model coincides well with experimental and simulation results from other researchers. A linear relationship is found between the average relative grain size and the grain face number. More specifically, for average relative grain sizes exceeding 0.5, the number of faces increases linearly with relative grain size. For average relative grain sizes meaning by adjusting the actual temperature, space, and time for austenitic grain growth. The calibrated results are found to be in agreement with the simulation results from other research as well as the experimental results. By means of calibration of the proposed model, we can reliably predict the grain size in actual grain growth.

  2. Dendritic grain growth simulation in weld pool of nickel base alloy

    Institute of Scientific and Technical Information of China (English)

    Zhan Xiaohong; Wei Yanhong; Ma Rui; Dong Zhibo

    2008-01-01

    Dendritic grain growth at the edge of the weld pool is simulated using a stochastic numerical model of cellular automaton algorithm. The grain growth model is established based upon the balance of solute in the solid/liquid interface of the dendrite tip. Considering the complicated nucleation condition and competitive growth, the dendrite morphologies of different nucleation condition are simulated. The simulated results reproduced the dendrite grain evolution process at the edge of the weld pool. It is indicated that the nucleation condition is an important factor influencing the grain morphologies especially the morphologies of secondary and tertiary arms.

  3. Modelling grain growth in the presence of Zener drag: application for Fe-3% Si

    Science.gov (United States)

    Maazi, N.; Rouag, N.

    2001-09-01

    The presence of AlN and MnS inhibitors in Fe-3%Si sheets, grade Hi-B, permits the development of Goss texture by the sudden and rapid growth of small grains possessing a {110} orientation. This behaviour is not in good agreement with the classical laws of secondary recrystallization. In the present study, first the minimum critical radius of the grain which is susceptible to growth is determined in relation to orientation and grain size neighbourhood. Moreover, the necessity to define a maximum critical radius for the neighbourhood is established. Consideration of these two radii permits the exploration of possible growth sequences for small grains.

  4. INFLUENCE OF ABNORMAL AUSTENITE GRAIN GRAIN GROWTH IN QUENCHED ABNT 5135 STEEL

    Directory of Open Access Journals (Sweden)

    Camila de Brito Ferreira

    2015-03-01

    Full Text Available Grain size in the steels is a relevant aspect in quenching and tempering heat treatments. It is known that high austenitizing temperature and long time provide an increase in austenitic grain sizes. Likewise, after hardening of low alloy steel, the microstructure consists of martensite and a volume fraction of retained austenite. This paper evaluates the influence of austenite grain size on the volume fraction of retained austenite measured by metallographic analyses and X-ray diffraction. The Mi and Mf temperatures were calculated using an empirical equation and experimentally determined by differential thermal analysis. The mechanical behavior of the steel was evaluated by Vickers microhardness testing. Differently from other results published in the literature that steel hardenability increases with the austenite grain size, it was observed that the increase in austenite grain promotes greater volume fraction of retained austenite after water quenching.

  5. Influence of grain growth on the structural properties of the nanocrystalline Gd2Ti2O7

    Science.gov (United States)

    Kulriya, P. K.; Yao, Tiankai; Scott, Spencer Michael; Nanda, Sonal; Lian, Jie

    2017-04-01

    The microstructural evolution and grain growth kinetics of the nanocrystalline Gd2Ti2O7 drastically affect its properties and functionalities as thermal barrier coatings and nuclear waste forms for actinide incorporation. Here, we report the synthesis of the dense nano-sized Gd2Ti2O7 by high energy ball milling (HEBM), and spark plasma sintering (SPS), and also investigated the isothermally annealing induced grain coarsening and structural properties variations. As-prepared nano powder (D∼60 nm) by HEBM exhibited an amorphous nature, which was consolidated to a dense single phase crystalline pyrochlore nano-ceramic (D∼120 ± 10 nm) by SPS sintering at 1200 °C. Isothermal annealing was performed at different temperatures (1300 °C - 1500 °C) with holding time varying from 0.5 to 8 h, and the pyrochlore phase is stable with no indication of a transformation into a defect fluorite structure. A rapid initial grain growth was observed which increased with temperature and annealing durations due to the large driving force of the curvature-driven grain coarsening of the nano-ceramics, and grain growth saturates at longer durations. The calculated value of the time constant and activation energy for the nanocrystalline Gd2Ti2O7 were 0.52 ± 0.02 and 240 ± 20 kJ/mol (∼2.48 eV), respectively. The enhanced grain growth kinetics with a lower value of activation energy can be explained by the effect of fast diffusion across the grain boundaries for dense nanoceramics.

  6. Effect of surface roughness on grain growth and sintering of alumina

    Indian Academy of Sciences (India)

    Padmaja Parameswaran Nampi; Shoichi Kume; Yuji Hotta; Koji Watari

    2011-07-01

    The production of ceramic bodies with less surface roughness is industrially important when one considers the aspect of final machining processes. Hence an attempt have been made to study the variation in surface roughness parameters (a, y, z) of alumina having three different kinds of roughness features at different sintering temperatures. Variation in surface roughness properties are also correlated with grain size. z shows significant difference between fine and intermediate surfaces, hence predicts small difference in their microstructural features. As a general trend, average grain size increases with increase in sintering temperature, but wide distribution of grains with enhanced non-uniform grain growth is observed when the surface is coarse. Hence, creation of fine surface in the green body is necessary for homogeneously distributed grains with controlled uniform grain growth. The final roughness and grain size of the sintered alumina depend on the initial surface roughness of the green body.

  7. Phase-field theory of grain growth in the presence of mobile second-phase particles

    Energy Technology Data Exchange (ETDEWEB)

    Vedantam, Srikanth, E-mail: srikanth@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore, Singapore 117576 (Singapore); Mallick, Ashis [Department of Mechanical Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2010-01-15

    We have developed a phase-field model for grain growth in the presence of mobile second-phase particles. In this model, each grain and particle is represented by a unique order parameter. The grain boundaries sweep the mobile particles during grain growth. The particle velocity is taken to be proportional to the driving force arising from the curvature of the phase boundary in the neighborhood of the particle. The proportionality factor is the constitutive parameter representing the mobility of the particle. We first study the model in a one-dimensional axisymmetric setting and compare the results with theoretical calculations. We then study the interaction of a bicrystal grain boundary with a dilute distribution of particles. Finally we show the effect of particles on polycrystalline grain growth.

  8. A model for grain growth based on the novel description of dendrite shape

    Directory of Open Access Journals (Sweden)

    O. Wodo

    2007-12-01

    Full Text Available We use novel description of dendritic shape in the micro solid phase growth model. The model describes evolution of both primary solid solution dendrite and eutectic that forms between arms and grains in the last stage of solidification. Obtained results show that our approach can be used in grain growth model to determine more reliable eutectic distribution. In the paper no kinetics connected with the eutectic transformation is taken into account. However, this does not affect the eutectic distribution because at the beginning of eutectic reaction all liquid phase was assumed to fully transform into eutectic. Results for solid phase growth model based on this description are presented. The obtained results of eutectic distribution are especially important in the hypoeutectic alloy solidification case, where the eutectic grains grow between formed solid solution grains. Thus, the distribution of solid solution grain becomes crucial due to its influence on the delay in solid fraction increase of eutectic grains.

  9. Dynamic recrystallization and grain growth in olivine rocks

    NARCIS (Netherlands)

    Kellermann Slotemaker, A.

    2006-01-01

    A mechanism based description of the rheology of olivine is essential for modeling of upper mantle geodynamics. Previously, mantle flow has been investigated using flow laws for grain size insensitive (GSI) dislocation creep and/or grain size sensitive (GSS) diffusion creep of olivine. Generally,

  10. Dynamic recrystallization and grain growth in olivine rocks

    NARCIS (Netherlands)

    Kellermann Slotemaker, A.

    2006-01-01

    A mechanism based description of the rheology of olivine is essential for modeling of upper mantle geodynamics. Previously, mantle flow has been investigated using flow laws for grain size insensitive (GSI) dislocation creep and/or grain size sensitive (GSS) diffusion creep of olivine. Generally, fl

  11. Effect of fermentation and extrusion on the release of selected minerals from lupine grain preparations

    Directory of Open Access Journals (Sweden)

    Rafał W. Wójciak

    2009-09-01

    Full Text Available Introduction. Antinutritional factors in legumes lower the nutritional value of foods by lowering the digestibility or bioavailability of nutrients. Technological processes applied in food production (e.g. extrusion, fermentation, germination may influence the leguminous seeds matrix composition which in consequence may affect (improve or decrease mineral bioaccessibility and uptake in animals and humans. The aim of this study was to determine the effect of fermentation and extrusion processing, as well as their combination, on the potential availability of Fe, Cu, and Zn from lupine grain preparations. Materials and methods. The content and the release of Fe, Cu and Zn from three different lupine species (Lupinus albus, Lupinus luteus, Lupinus angustifolius was determined. The samples were subjected to enzymatic digestion under in vitro conditions. The content of minerals in lupine grains before and after enzymatic digestion was determined by the flame atomic absorption spectrometry. Results. The degree of release of Fe, Cu, and Zn from dehulled lupine grains was higher than from whole grains. Fermentation processing increased the degree of Fe release, extrusion decreased the degree of Cu release, while the extrusion after fermentation processing increased the degree of Fe release from lupine grain preparations. Conclusions. The degree of mineral release from lupine grains depends on the hull content, technological processing applied and the lupine variety.

  12. Strain-induced grain growth of cryomilled nanocrystalline Al in trimodal composites during forging

    Energy Technology Data Exchange (ETDEWEB)

    Yao, B. [Advanced Materials Processing and Analysis Center, and Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Simkin, B.; Majumdar, B. [Materials and Metallurgical Engineering Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States); Smith, C.; Bergh, M. van den [DWA Aluminum Composites, Chatsworth, CA 91311 (United States); Cho, K. [Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Sohn, Y.H., E-mail: Yongho.Sohn@ucf.edu [Advanced Materials Processing and Analysis Center, and Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States)

    2012-02-28

    Highlights: Black-Right-Pointing-Pointer Grain growth of cryomilled nanocrystalline aluminum during hot forging. Black-Right-Pointing-Pointer Use of hollow cone dark field imaging technique in TEM for grain size measurement. Black-Right-Pointing-Pointer Grain growth model of strain, strain rate and temperature for forging optimization. - Abstract: Grain growth of nanocrystalline aluminum ({sup nc}Al) in trimodal Al metal-matrix-composites (MMCs) during hot forging was investigated. The {sup nc}Al phase formed through cryomilling of inert gas-atomized powders in liquid nitrogen has an average grain size down to 21 nm, exhibits excellent thermal stability. However, substantial grain growth of {sup nc}Al up to 63 nm was observed when the Al MMCs were thermo-mechanically processed even at relatively low temperatures. Grain growth of the cryomilled {sup nc}Al phase in trimodal Al MMCs after hot forging was documented with respect to temperature ranging from 175 Degree-Sign C to 287 Degree-Sign C, true strain ranging from 0.4 to 1.35 and strain rate ranging from 0.1 to 0.5 s{sup -1}. Hollow cone dark field imaging technique was employed to provide statistically confident measurements of {sup nc}Al grain size that ranged from 21 to 63 nm. An increase in forging temperature and an increase in true strain were correlated with an increase in grain size of {sup nc}Al. Results were correlated to devise a phenomenological grain growth model for forging that takes strain, strain rate and temperature into consideration. Activation energy for the grain growth during thermo-mechanical hot-forging was determined to be 35 kJ/mol, approximately a quarter of activation energy for bulk diffusion of Al and a half of activation energy for static recrystallization.

  13. Modeling of Austenite Grain Growth During Austenitization in a Low Alloy Steel

    Science.gov (United States)

    Dong, Dingqian; Chen, Fei; Cui, Zhenshan

    2016-01-01

    The main purpose of this work is to develop a pragmatic model to predict austenite grain growth in a nuclear reactor pressure vessel steel. Austenite grain growth kinetics has been investigated under different heating conditions, involving heating temperature, holding time, as well as heating rate. Based on the experimental results, the mathematical model was established by regression analysis. The model predictions present a good agreement with the experimental data. Meanwhile, grain boundary precipitates and pinning effects on grain growth were studied by transmission electron microscopy. It is found that with the increasing of the temperature, the second-phase particles tend to be dissolved and the pinning effects become smaller, which results in a rapid growth of certain large grains with favorable orientation. The results from this study provide the basis for the establishment of large-sized ingot heating specification for SA508-III steel.

  14. Grain growth and thermal stability accompanying recrystallization in undercooled Ni-3at.%Sn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z., E-mail: chenzheng1218@163.com [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an, Shaanxi 710016 (China); Chen, Q.; Shen, C.J. [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Liu, F. [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an, Shaanxi 710016 (China)

    2015-10-15

    The grain growth and thermal stability after recrystallization in as-solidified highly undercooled Ni-3at.%Sn alloy melt were investigated. As for undercooled Ni-3at.%Sn alloy, a transition from dendritic to granular crystals occurred when ΔT≥ΔT{sup *}, which was induced by the plastic deformation of dendrites and subsequent recrystallization. On this basis, the subsequent grain growth and solute segregation accompanying recalescence were calculated by a recently proposed thermo-kinetic model, which showed close agreement with the experimental results. It is concluded that the grain growth process was interrelated to recalescence, solute trapping and solute segregation of Sn atoms captured by solute trapping, which was responsible for the reduction of grain boundary energy and improvement of thermal stability. - Highlights: • A transition from dendritic to granular crystals occurred when ΔT≥ΔT{sup *}. • The grain growth accompanying recalescence was calculated. • A close agreement with the experimental results was shown.

  15. The Effect of Eectronic Energy Loss on Irradiation-Induced Grain Growth in Nanocrystalline Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanwen; Aidhy, Dilpuneet S.; Varga, Tamas; Moll, Sandra; Edmondson, P. D.; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N.; Weber, William J.

    2014-01-01

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, contributions from both displacement damage and ionization to the grain growth are identified. Our atomistic simulations have revealed fast grain boundary (GB) movements due to the high density of disorder near GBs. Our experimental results have shown that irradiation-induced grain growth is a function of total energy deposited, where the excitation of target electrons and displacement of lattice atoms both contribute to the overall disorder and both play important roles in grain growth. The coupling of energy deposition to the electronic and lattice structures should both be taken into consideration when engineering nanostructural materials.

  16. Identification of Accretion as Grain Growth Mechanism in Astrophysically Relevant Water&ice Dusty Plasma Experiment

    Science.gov (United States)

    Marshall, Ryan S.; Chai, Kil-Byoung; Bellan, Paul M.

    2017-03-01

    The grain growth process in the Caltech water–ice dusty plasma experiment has been studied using a high-speed camera and a long-distance microscope lens. It is observed that (i) the ice grain number density decreases fourfold as the average grain major axis increases from 20 to 80 μm, (ii) the major axis length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge resulting in strong mutual repulsion and this, combined with the fractal character of the ice grains, prevents them from agglomerating. In order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains, the volumetric packing factor (i.e., ratio of the actual volume to the volume of a circumscribing ellipsoid) of the ice grains must be less than ∼0.1 depending on the exact relative velocity of the grains in question. Thus, it is concluded that direct accretion of water molecules is very likely to dominate the observed ice grain growth.

  17. Effect of electric current pulse on grain growth in superplastic deformation of 2091 Al-Li alloy

    Institute of Scientific and Technical Information of China (English)

    刘志义; 许晓嫦; 崔建忠

    2003-01-01

    The effect of electric current pulse on the grain growth in the superplastic deformation of 2091 Al-Li alloy was investigated. Optical metallographic microstructure observation and average linear intercept measuring results show that at same strain, the grain size in the superplastic deformation loaded with electric current pulse is smaller than that unemploying electric current pulse, and so does the grain growth rate. TEM observation shows that the dislocation density at grain boundary in the superplastic deformation applied with electric current pulse is lower than that unemploying electric current pulse.It indicates that electric current pulse increases the rate of dislocation slip and climb in grain boundary, which leads to a decrease of both the density of the dislocation slipping across grain boundary at same strain rate and the driving force for grain growth, therefore the rate of grain growth decreases.The established model for grain growth shows an exponential relation of grain size with strain.

  18. Effect of polymorphism of Al2O3 on sintering and grain growth of magnesia aluminate spinel

    Directory of Open Access Journals (Sweden)

    Zhihui Z.

    2007-01-01

    Full Text Available The effect of polymorphism of Al2O3 on sintering and grain growth of magnesia aluminate spinel was studied. γ - Al2O3 and α - Al2O3 were mixed with MgO according to the stoichiometric MA ratio, respectively, and pressed into billets with a 20mm diameter and 15mm height, and then were sintered at temperature from 1250ºC to 1400ºC in air atmosphere. Bulk density, apparent porosity and grain size were measured. The results indicated that the grain size of MA with γ-Al2O3 is larger than the grain size of MA with α - Al2O3. This is because the activation energy of grain growth of magnesia aluminate spinel prepared by γ-Al2O3 is lower than that by α -Al2O3, the former is 159KJ/mol and the latter is 217KJ/mol.

  19. 4D Study of Grain Growth in Armco Iron Using Laboratory X-ray Diffraction Contrast Tomography

    DEFF Research Database (Denmark)

    Sun, Jun; Lyckegaard, Allan; Zhang, Yubin

    2017-01-01

    grains were determined at three temporal states during annealing. The correlation between growth of grains and grain orientation is explored. The results demonstrate the capability of the LabDCT technique to allow detailed studies of grain growth, and thereby provide the necessary 4D experimental......Using a novel laboratory diffraction contrast tomography (LabDCT) technique, a non-destructive 4D study was conducted to investigate the evolution in 3D of the grain structure during grain growth in an Armco iron sample. The 3D grain morphology and the crystallographic orientations of more than 300...

  20. In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

    Institute of Scientific and Technical Information of China (English)

    Xiang-liang Wan; Kai-ming Wu; Gang Huang; Ran Wei; Lin Cheng

    2014-01-01

    The austenite grain growth behavior in a simulated coarse-grained heat-affected zone during thermal cycling was investigated via in situ observation. Austenite grains nucleated at ferrite grain boundaries and then grew in different directions through movement of grain boundaries into the ferrite phase. Subsequently, the adjacent austenite grains impinged against each other during theα→γtransformation. After theα→γtransformation, austenite grains coarsened via the coalescence of small grains and via boundary migration between grains. The growth process of austenite grains was a continuous process during heating, isothermal holding, and cooling in simulated thermal cy-cling. Abundant finely dispersed nanoscale TiN particles in a steel specimen containing 0.012wt%Ti effectively retarded the grain boundary migration, which resulted in refined austenite grains. When the Ti concentration in the steel was increased, the number of TiN particles de-creased and their size coarsened. The big particles were not effective in pinning the austenite grain boundary movement and resulted in coarse austenite grains.

  1. Control of equiaxed grains in a complicated Cu-Ni based alloy prepared by centrifugal casting

    Directory of Open Access Journals (Sweden)

    Luo Zongqiang

    2011-02-01

    Full Text Available A complicated Cu-Ni based alloy was developed to fabricate wear-resisting bush for high temperature application. The concern focuses on the control of equiaxed grains in the developed alloy ingot prepared by centrifugal casting. The results show that the equiaxed grains are determined by the pouring temperature of the melt, the cooling rate and the rotation speed of the mold. With the decrease in pouring temperature, the fraction of the equiaxed grains in the transverse section of the ingot increases and the average length of columnar grain decreases. When the pouring temperature is confined below 1,250℃, complete equiaxed grains can be obtained. Based on the optimal centrifugal casting processing, the tensile strength of the developed alloy ingot with complete equiaxed grains reaches to 810 MPa and 435 MPa at room temperature and 500℃, respectively, which is 14% and 110% higher than that of common commercial QAl10-4-4 alloy. The wear rate of the developed alloy is 7.0 × 10-8 and 3.8 × 10-7 mm3•N-1•mm-1 at room temperature and 500℃, respectively, which is 5 times and 39 times lower than that of QAl10-4-4 alloy.

  2. Dynamic Grain Growth in Forsterite Aggregates Experimentally Deformed to High Strain

    Science.gov (United States)

    Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.; Drury, M.

    2004-12-01

    The dynamics of the outer Earth are largely controlled by olivine rheology. From previous work it has become clear that if olivine rocks are deformed to high strain, substantial weakening may occur before steady state mechanical behaviour is approached. This weakening appears directly related to progressive modification of the grain size distribution through competing effects of dynamic recrystallization and syn-deformational grain growth. However, most of our understanding of these processes in olivine comes from tests on coarse-grained materials that were reduced in grain size during straining by grain size insensitive (dislocation) creep mechanisms. The aim of the present study was to investigate microstructure evolution of fine-grained olivine rocks that coarsen in grain size while deforming by grain size sensitive (GSS) creep. We used fine-grained (~1 μ m) olivine aggregates (i.e., forsterite/Mg2SiO4), containing ~0.5 wt% water and 10 vol% enstatite (MgSiO3). Two types of experiments were carried out: 1) Hot isostatic pressing (HIP) followed by axial compression to varying strains up to a maximum of ~45%, at 600 MPa confining pressure and a temperature of 950°C, 2) HIP treatment without axial deformation. Microstructures were characterized by analyzing full grain size distributions and texture using SEM/EBSD. Our stress-strain curves showed continuous hardening. When samples were temporally unloaded for short time intervals, no difference in flow stress was observed before and after the interruption in straining. Strain rate sensitivity analysis showed a low value of ~1.5 for the stress exponent n. Measured grain sizes show an increase with strain up to a value twice that of the starting value. HIP-only samples showed only minor increase in grain size. A random LPO combined with the low n ~1.5 suggests dominant GSS creep controlled by grain boundary sliding. These results indicate that dynamic grain growth occurs in forsterite aggregates deforming by GSS

  3. Grain growth in four dimensions: A comparison between simulation and experiment

    DEFF Research Database (Denmark)

    McKenna, I.M.; Poulsen, S.O.; Lauridsen, Erik Mejdal;

    2014-01-01

    A 3-D isotropic phase field simulation was used to predict the morphology of individual grains during grain growth. The simulation employed a polycrystalline array of titanium alloy Ti-β-21S experimentally characterized by X-ray tomography as an initial condition. The non-destructive nature of X...

  4. Grain growth kinetics of textured-BaTiO3 ceramics

    Indian Academy of Sciences (India)

    Fang Fu; Jiwei Zhai; Zhengkui Xu; Bo Shen; Xi Yao

    2014-06-01

    Textured BaTiO3 (BT) ceramics were fabricated by templated grain growth method. Effects of sintering conditions on the grain growth process of textured-BT ceramics were investigated. Orientation degree increased initially and then decreased with increasing soaking time. The ceramics were composed of equiaxed matrix grains and brick-like template particles. The brick-like particles aligned parallel to the casting direction by observing from SEM images. A (ℎ00)-preferred orientation was confirmed by SAED and XRD patterns. Mechanism of grain growth in textured-BT ceramics was studied. Both consumption of matrix by templates and grain growth of templates determined the orientation degree of ceramics. The kinetic mechanism for grain orientation was also discussed by the simplified phenomenological kinetic equation. The average activation energies were 364 kJ/mol for matrix grain and 918 kJ/mol for template particle, respectively. Finally, a dense ceramic with 85% grain orientation was obtained after sintering at 1400°C for 2 h.

  5. Enhancing the High Temperature Capability of Nanocrystalline Alloys: Utilizing Thermodynamic Stability Maps to Mitigate Grain Growth Through Solute Selection

    Science.gov (United States)

    2013-12-01

    nanocrystalline alloys. nanocrystalline materials , grain growth, grain boundary energy, grain boundary segregation 46 Mark A. Tschopp 410-306...grant DMR-1005677. vi 1. Introduction For nanocrystalline materials to be useful, they must be sufficiently resistant to grain growth at elevated...temperatures to retain their nanoscale grain size (d < 100 nm). One strategy for stabilizing nanocrystalline materials is to add segregating solutes to

  6. Recrystallization and Grain Growth in Austenitic Stainless Steels: a Statistical Approach

    Institute of Scientific and Technical Information of China (English)

    A.Di Schino; G.Abbruzzese; J.M. Kenny

    2003-01-01

    A mathematical model, able to describe the recrystallization and grain growth in metals, has been developed. Taking into account the classical constitutive equations of the Taylor′s theory, the model involves only two free parameters (the dislocation den

  7. MODELING OF FERRITE GRAIN GROWTH OF LOW CARBON STEELS DURING HOT ROLLING

    Institute of Scientific and Technical Information of China (English)

    Y.T. Zhang; D.Z. Li; Y.Y. Li

    2002-01-01

    For most commercial steels the prediction of the final properties depends on accuratelycalculating the room temperature ferrite grain size. A grain growth model is proposedfor low carbon steels Q235B during hot rolling. By using this model, the initial ferritegrain size after continuous cooling and ferrite grain growing in coiling procedure canbe predicted. Finally, in-plant trials were performed in the hot strip mill of Ansteel.The calculated final ferrite grain sizes are in good agreement with the experimentalones. It is helpful both for simulation of microstructure evolution and prediction ofmechanical properties.

  8. Abnormal grain growth effects on the mechanical behavior of Ni electrodeposits

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, O. [LMT-Cachan, ENS Cachan/CNRS-UMR 8535/Univ. Paris VI, Cachan (France); Lab. de Mecanique et Genie Civil, Univ. Montpellier II, Montpellier (France); Hubert, O.; Hild, F. [LMT-Cachan, ENS Cachan/CNRS-UMR 8535/Univ. Paris VI, Cachan (France)

    2004-07-01

    The study deals with the long-term reliability of a high precision pressure sensor using bellows. They are mainly made of electroplated Ni whose thermal stability is investigated by DSC. EBSD measurements and SEM observations give some evidence for an abnormal grain growth mechanism whose effects on the elasto-plastic properties of the Ni deposit are experimentally investigated. Abnormal grain growth leads to an increase in the elastic modulus and a strong decrease in the yield strength. (orig.)

  9. Reverse Austenite Transformation and Grain Growth in a Low-Carbon Steel

    Science.gov (United States)

    Garcin, Thomas; Ueda, Keiji; Militzer, Matthias

    2017-02-01

    The mechanisms controlling the reverse austenite transformation and the subsequent grain growth are examined in a low-carbon steel during slow continuous heating. The ex-situ metallographic analysis of quenched samples is complemented by in-situ dilatometry of the phase transformation and real-time laser ultrasonic measurements of the austenite grain size. Although the initial state of the microstructure (bainite or martensite) has only limited impact on the austenite transformation temperature, it has significant influence on the mean austenite grain size and the rate of grain growth. The coarsening of austenite islands during reverse transformation occurring from the martensitic microstructure is responsible for a large austenite grain structure at the completion of the austenite formation. On the other hand, a much finer austenite grain size is obtained when the austenite transforms from the bainite microstructure. Upon further heating, the rate of austenite grain growth is limited by the presence of nanometric precipitates present in the bainite microstructure leading to a significantly finer austenite grain size. These results give important guidance for the design of thermomechanical-controlled processing of heavy-gage steel plates.

  10. Redistribution of mineral elements in wheat grain when applying the complex enzyme preparations based on phytase

    Directory of Open Access Journals (Sweden)

    Elena Kuznetsova

    2016-01-01

    Full Text Available Biogenic minerals play an important role in the whole human nutrition, but they are included in the grain of the phytates that reduces their bioavailability. Whole wheat bread is generally considered a healthy food, but the presence of mineral elements in it is insignificant, because of weak phytate degradation. From all sources of exogenous phytase the most productive are microscopic fungi. To accelerate the process of transition hard mineral elements are mobilized to implement integrated cellulolytic enzyme preparation based on the actions of phytase (producer is Penicillium canescens. Phytase activity was assessed indirectly by the rate of release of phosphate from the substrate. It has been established that the release rate of the phosphoric acid substrate is dependent on the composition of the drug and the enzyme complex is determined by the presence of xylanase. The presented experimental data shows that a cellulase treatment of the grain in conjunction with the β-glucanase or xylanase leading to an increase in phytase activity could be 1.4 - 2.3 times as compared with the individual enzymes. As a result of concerted action of enzymes complex preparation varies topography grain, increase the pore sizes in seed and fruit shells that facilitate the penetration of the enzyme phytase in the aleurone layer to the site of phytin hydrolysis and leads to an increase in phytase activity. In terms of rational parameters of enzymatic hydrolysis, the distribution of mineral elements in the anatomical parts of the grain after processing complex enzyme preparation with the help of X-ray detector EMF miniCup system in a scanning electron microscope JEOL JSM 6390 were investigated. When processing enzyme preparation wheat trend in the distribution of mineral elements, characteristic of grain - the proportion of these elements in the aleurone layer decreases, and in the endosperm increases. Because dietary fiber and phytate found together in the

  11. Bounding box framework for efficient phase field simulation of grain growth in anisotropic systems

    CERN Document Server

    Vanherpe, L; Blanpain, B; Vandewalle, S

    2011-01-01

    A sparse bounding box algorithm is extended to perform efficient phase field simulations of grain growth in anisotropic systems. The extended bounding box framework allows to attribute different properties to different grain boundary types of a polycrystalline microstructure and can be combined with explicit, implicit or semi-implicit time stepping strategies. To illustrate the applicability of the software, the simulation results of a case study are analysed. They indicate the impact of a misorientation dependent boundary energy formulation on the evolution of the misorientation distribution of the grain boundary types and on the individual growth rates of the grains as a function of the number of grain faces. (C) 2011 Elsevier B.V. All rights reserved.

  12. Progress on grain growth dynamics in sintering of nano-powders

    Institute of Scientific and Technical Information of China (English)

    LIU Chunjing; WANG Xin; JIANG Yanfei; WANG Yongming; HAO Shunli

    2006-01-01

    Nanostructured materials, characterized by an ultrafine grain size, have stimulated much research interest by virtue of their unusual mechanical, electrical, optical, and magnetic properties. In this paper, the sintering process of nano-powders were reviewed, to which sintering of the traditional materials compared. The microstructural development, i.e., grain growth and densification during sintering as well as the mechanism of crystal surface diffusion and boundary migration were analyzed, and the dynamic models on sintering process were summarized by the relationship of grain growth and pores size, interface diffusion, densification rate, and sintering temperature. Finally, the research tendency of this major on the basis of above models was discussed.

  13. Dynamic Recrystallization and Grain Growth Behavior of 20SiMn Low Carbon Alloy Steel

    Institute of Scientific and Technical Information of China (English)

    DONG Lanfeng; ZHONG Yuexian; MA Qingxian; YUAN Chaolong; MA Lishen

    2008-01-01

    A senes of thermodynamics experiments were used to optimize the hot forging process of 20SiMn low-carbon alloy steel.A dynamic recrystallization and grain growth model was developed for the 20SiMn steel for common production conditions of heavy forgings by doing a nonlinear curve fit of the expenment data.Optimized forging parameters were developed based on the control of the dynamic recrystallization and the MnS secondary phase.The data shows that the initial grain size and the MnS secondary phase all affect the behavior of the 20SiMn dynamic recrystallization and grain growth.

  14. Infiltration techniques for suppressing grain growth during the densification of submicron and nanophase alumina composites

    Science.gov (United States)

    Vernon, Deborah Marshall

    Grain growth control during the final stages of densification is an issue with extreme technological significance. In the last decade, nanophase ceramic starting powders have become commercially available, and in order to take full advantage of the unique properties nanophase ceramics potentially offer, grain growth control during processing of these materials must be addressed. In this research study the author addresses the topic of suppression of grain growth in submicron and nanophase alumina using novel processing techniques. The approach used to decrease grain boundary motion during processing involves the addition of an intermediate step between initial powder pressing and sintering. During the intermediate step either solute amounts of an infiltrant are incorporated along grain boundary junctions through a vapor-phase technique or, second phase inclusions are formed within the pore structure of the ceramic porous compacts via a liquid-phase technique. Using the vapor-phase technique, silicon nitride was introduced into porous submicron and nanophase alumina compacts. It was determined that silicon nitride in amounts below the solubility limit is an effective grain growth inhibitor. In the submicron pellets studies, three regions of grain growth were observed: abnormal, suppressed, and normal. Using a mathematical model developed for simulating the vapor infiltration process, a range of silicon concentrations (70 to 50 ppm) was determined to correspond to the suppressed grain growth region. In the nanophase silicon nitride infiltrated pellets, suppression of grain growth was observed throughout the infiltrated specimen, however the suppression effects were not great enough to retain the nanosized nature of the alumina grains. Using the liquid-phase technique, zirconia particles were formed within the pore structure of submicron and nanophase alumina compacts. A comparison between suppression effects in compacts created by liquid-phase and by powder

  15. Preparation and investigation of ultrafine-grained tungsten carbide with high hardness and fracture toughness

    Science.gov (United States)

    Chuvil'deev, V. N.; Blagoveshchenskii, Yu. V.; Sakharov, N. V.; Boldin, M. S.; Nokhrin, A. V.; Isaeva, N. V.; Shotin, S. V.; Lopatin, Yu. G.; Smirnova, E. S.

    2015-07-01

    High-density samples of ultrafine-grained tungsten carbide with high hardness (up to 31-34 GPa) and increased fracture toughness (up to 5.2-6.4 MPa m1/2) are obtained using the technology of electropulse plasma sintering. The influence of the initial size of nanoparticles of α-WC prepared by plasmachemical synthesis on the density, structural parameters, and mechanical properties of tungsten carbide is investigated.

  16. Combining cellular automata and Monte Carlo algorithm to simulate three-dimensional grain growth

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; CHEN Ju-hua; GUO Pei-quan; ZHAO Ping

    2006-01-01

    A 3-D simulation of grain growth was conducted by utilizing cellular automata (CA) and Monte Carlo (MC) algorithm. In the simulating procedure, the three-dimensional space is divided into a large number of 2-D isometric planes. Then, each of the planes is divided into identical square cells. Finally, the cellular automata and Monte Carlo algorithm are combined together to simulate the grain growth. Through an evolutionary simulation, the recrystallized microstructure, the grain growth rate and the grain size distribution are acceptably predicted. The simulation routine can be used to simulate the real physical-metallurgy processes and to predict quantitative dynamic information of the evolution of microstructure. Further more, the method is also useful for optimization of materials properties by controlling the microstructure evolution.

  17. Abnormal grain growth in Eurofer-97 steel in the ferrite phase field

    Science.gov (United States)

    Oliveira, V. B.; Sandim, H. R. Z.; Raabe, D.

    2017-03-01

    Reduced-activation ferritic-martensitic (RAFM) Eurofer-97 steel is a candidate material for structural applications in future fusion reactors. Depending on the amount of prior cold rolling strain and annealing temperature, important solid-state softening reactions such as recovery, recrystallization, and grain growth occur. Eurofer-97 steel was cold rolled up to 70, 80 and 90% reductions in thickness and annealed in the ferrite phase field (below ≈ 800 °C). Changes in microstructure, micro-, and mesotexture were followed by orientation mappings provided by electron backscatter diffraction (EBSD). Eurofer-97 steel undergoes abnormal grain growth above 650 °C and this solid-state reaction seems to be closely related to the high mobility of a few special grain boundaries that overcome pinning effects caused by fine particles. This solid-state reaction promotes important changes in the microstructure and microtexture of this steel. Abnormal grain growth kinetics for each condition was determined by means of quantitative metallography.

  18. Effects of grain size and porosity on strength of Li2TiO3 tritium breeding pebbles and its grain growth behavior

    Science.gov (United States)

    Xiang, Maoqiao; Zhang, Yingchun; Zhang, Yun; Wang, Chaofu; Liu, Wei; Yu, Yonghong

    2016-12-01

    Tons of Li2TiO3 tritium breeding pebbles will be filled in the blanket for obtaining tritium fuel. In this work, isothermal sintering was carried out to study the grain growth behavior of the Li2TiO3 pebbles fabricated by agarose method. The grain growth exponent (n) and the activation energy (Q) calculated by the phenomenological kinetic equation were 2 and 435.65 kJ/mol, respectively. The grain growth was controlled by vapor transport (p = 2S/r). In addition, effects of porosity and grain-size on the strength of Li2TiO3 pebbles were investigated. The strength was affected by the grain size and the porosity of Li2TiO3 pebbles, and high strength (about 72 MPa) depended partly on achieving the optimum balance between the porosity (about 10%) and grain size (about 2 μm).

  19. The role of gallium sulfide in SrS:Ce grain growth

    Energy Technology Data Exchange (ETDEWEB)

    Evans, N.D. [Oak Ridge Inst. for Science and Education, TN (United States); Naman, A.; Jones, K.S.; Holloway, P.H. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Rice, P.M. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-04-01

    Whereas efficient red (ZnS:Mn) and green (ZnS:Tb) phosphors are available for full-color flat-panel display technology, efficient blue phosphors are still under development. SrS:Ce is being investigated as a suitable material. As part of a larger study, annealed SrS:Ce films produced from sputter targets incorporating Ga{sub 2}S{sub 3} were found to be five times brighter than films produced from targets containing no Ga{sub 2}S{sub 3}. Consequently, the significance of added gallium sulfide to the morphology of SrS:Ce films during annealing is being investigated. Following deposition, plan view specimens of films were prepared for transmission electron microscopy by mechanical grinding, dimpling, and Ar{sup +} milling. Films were examined in a Philips CM12, and a JEOL 200CX. Additionally, EDS line scans were obtained in the scanning-transmission mode of a Philips CM200FEG, integrated with an EMiSPEC Vision acquisition system. The EDS line scans were defined as a series of 40 points along a line, spaced approximately 3.6 nm apart. The dwell time for EDS acquisition at each point was 10 sec. It was found that the addition of Ga{sub 2}S{sub 3} increases the brightness of SrS:Ce films by enhancing grain growth during annealing. Also being investigated is the possibility that Ga{sub 2}S{sub 3}, either as a sub-sulfide or as a source of Ga, is involved in a liquid-phase sintering mechanism, which would account for the increased grain growth observed after annealing.

  20. Electrical Properties and Grain Growth Kinetics of PZN-based Ceramics Using Microwave Sintering

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Effectiveness of microwave sintering process through investigation of microstructural characteristics and electrical properties of x(0.94PbZn1/3 Nb2/3O3 + 0.06BaTiO3) + (1 - x)PbZryTi1-yO3 (PBZNZT) ceramics with x = 0.6 and y = 0.52 was evaluated. The relative density of 95% was achieved with sintering at 800℃ for 2 h. The small grain growth exponents indicate how easy the grain growth in these materials sintered using microwave radiation. Grain growth rate increases abruptly and is higher than that of conventional sintering at a temperature higher than 1050℃. This is attributed to the lower activation energy and higher grain boundary mobility. The activation energy required for the grain growth is found to be 132kJ/mol. Higher remanent polarization (Pr = 50.1μC/cm2) and increase in remanent polarization with sintering temperature are observed in microwave sintering process when compared to that of conventional sintering process,due to fast increase in grain growth rate and homogeneity in the specimen. The results indicate lower sintering energy and reduction of PbO pollution in the working environment by microwave sintering process.

  1. Effect of Mg on the Grain Growth and Dislocation Creep of Calcite

    Science.gov (United States)

    Xu, L.

    2004-12-01

    We tested the effect of variations in the amount of the solute impurity (Mg) on grain growth and strength of calcite aggregate. Synthetic marbles were produced by hot isostatic pressing mixtures of powders of calcite and dolomite at 850° C and 300 MPa confining pressure for different intervals (2 to 30 hrs). The HIP treatment resulted in homogeneous aggregates of calcite with Mg content from 0.5 to 17 mol%. Stress stepping tests and constant strain rate tests were used to examine the effect of Mg content on the dislocation creep of calcite. The grain growth rate under static conditions was decreased with Mg content from 7 to 17 mol%, indicating perhaps that grain boundary mobility is suppressed by the solute drag effect. In the diffusion creep at stresses below 40 Mpa, the strength of calcite decreases with increasing Mg content owing to the difference in grain size at 800° C and 300 MPa confining pressure. The contribution of dislocation creep increases with increasing stress, and the transition between diffusion and dislocation creep occurs at higher stresses for the samples with higher magnesium content and smaller grain size. The creep data were fit assuming a composite flow law consisting of a linear combination of diffusion and dislocation creep and a single-valued grain size. The best agreement was obtained by using a dislocation creep law with exponential dependence of strain rate on stress (e.g. Peierls law). More evidence from microstructure is needed to identify the dominant deformation mechanism conclusively. Most of the samples were compressed up to strains of 0.25; small recrystallized grains are formed resulting in a bimodal grain size distribution in some of the deformed samples. Preliminary data shows that the recrystallized grain sizes are smaller for Mg-calcite compared with that of pure calcite. This study will help to understand the effect of impurities on grain-growth kinetics and strain weakening in localized shear zones.

  2. Austenite grain growth simulation considering the solute-drag effect and pinning effect

    Science.gov (United States)

    Fujiyama, Naoto; Nishibata, Toshinobu; Seki, Akira; Hirata, Hiroyuki; Kojima, Kazuhiro; Ogawa, Kazuhiro

    2017-01-01

    Abstract The pinning effect is useful for restraining austenite grain growth in low alloy steel and improving heat affected zone toughness in welded joints. We propose a new calculation model for predicting austenite grain growth behavior. The model is mainly comprised of two theories: the solute-drag effect and the pinning effect of TiN precipitates. The calculation of the solute-drag effect is based on the hypothesis that the width of each austenite grain boundary is constant and that the element content maintains equilibrium segregation at the austenite grain boundaries. We used Hillert’s law under the assumption that the austenite grain boundary phase is a liquid so that we could estimate the equilibrium solute concentration at the austenite grain boundaries. The equilibrium solute concentration was calculated using the Thermo-Calc software. Pinning effect was estimated by Nishizawa’s equation. The calculated austenite grain growth at 1473–1673 K showed excellent correspondence with the experimental results. PMID:28179962

  3. Grain growth and morphology of In{sub 2}O{sub 3}:Pd nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Amani, Matin; Gregory, Otto J., E-mail: gregory@egr.uri.edu

    2013-09-02

    Thin film nanocomposites based on semiconducting oxides and palladium have been systematically studied using combinatorial chemistry techniques to optimize their thermoelectric properties. These nanocomposites have considerable potential for energy harvesting applications in harsh environments and were prepared by embedding palladium nanoparticles into an indium oxide matrix via co-sputtering from metal and ceramic targets. The as-deposited films were largely amorphous and thus were subsequently heat treated in nitrogen ambients to produce crystalline nanocomposites. These nanocomposite films were screened for their thermoelectric properties at room temperature as a function of composition, and the resulting films exhibited thermoelectric power factors that were significantly greater than the semiconducting oxides deposited directly from ceramic targets. Based on these rapid screening protocols employing hundreds of micro-thermocouples, the most promising nanocomposite films in terms of thermoelectric power factor were down-selected. Transmission electron microscopy, selected area electron diffraction, and scanning electron microscopy were then used to study the microstructural changes in these films as a function of temperature. When thermally cycled to 800 °C, an abrupt transition from normal, equiaxed grain growth to abnormal (spherulitic growth) was observed at a threshold palladium loading which was also optimal for thermoelectric energy harvesting. - Highlights: • Films consisting of Pd nanoparticles in an In{sub 2}O{sub 3} matrix were grown by sputtering. • These films have previously shown promising thermoelectric properties. • Transmission and scanning electron microscopy were used to investigate the films • This was determined for various compositions and annealing temperatures.

  4. Growing dust grains in protoplanetary discs - I. Radial drift with toy growth models

    Science.gov (United States)

    Laibe, Guillaume; Gonzalez, Jean-François; Maddison, Sarah T.

    2014-02-01

    In a series of papers, we present a comprehensive analytic study of the global motion of growing dust grains in protoplanetary discs, addressing both the radial drift and the vertical settling of the particles. Here we study how the radial drift of dust particles is affected by grain growth. In a first step, toy models in which grain growth can either be constant, accelerate or decelerate are introduced. The equations of motion are analytically integrable and therefore the grains dynamics is easy to understand. The radial motion of growing grains is governed by the relative efficiency of the growth and migration processes which is expressed by the dimensionless parameter Λ, as well as the exponents for the gas surface density and temperature profiles, denoted by p and q, respectively. When Λ is of the order of unity, growth and migration are strongly coupled, providing the most efficient radial drift. For the toy models considered, grains pile up when -p + q + 1/2 migration at a finite radius, thus avoiding being accreted on to the central star.

  5. Growing dust grains in protoplanetary discs - I. Radial drift with toy growth models

    CERN Document Server

    Laibe, Guillaume; Maddison, Sarah T

    2013-01-01

    In a series of papers, we present a comprehensive analytic study of the global motion of growing dust grains in protoplanetary discs, addressing both the radial drift and the vertical settling of the particles. Here we study how the radial drift of dust particles is affected by grain growth. In a first step, toy models in which grain growth can either be constant, accelerate or decelerate are introduced. The equations of motion are analytically integrable and therefore the grains dynamics is easy to understand. The radial motion of growing grains is governed by the relative efficiency of the growth and migration processes which is expressed by the dimensionless parameter Lambda, as well as the exponents for the gas surface density and temperature profiles, denoted p and q respectively. When Lambda is of order unity, growth and migration are strongly coupled, providing the most efficient radial drift. For the toy models considered, grains pile up when -p+q+1/2<0. Importantly, we show the existence of a seco...

  6. [Proteomics of rice leaf and grain at late growth stage under different nitrogen fertilization levels].

    Science.gov (United States)

    Ning, Shu-ju; Zhao, Min; Xiang, Xiao-liang; Wei, Dao-zhi

    2010-10-01

    Taking super-rice Liangyoupeijiu as test material, and by the method of two-dimensional gel electrophoresis (2-DE), this paper studied the changes in the leaf and grain proteomics of the variety at its late growth stage under different levels of nitrogen fertilization (1/2 times of normal nitrogen level, 20 mg x L(-1); normal nitrogen level, 40 mg x L(-1); 2 times of normal nitrogen level, 80 mg x L(-1)), with the biological functions of 16 leaf proteins, 9 inferior grain proteins, and 4 superior grain proteins identified and analyzed. Nitrogen fertilization could affect and regulate the plant photosynthesis via affecting the activation of photosynthesis-related enzymes and of CO2, the light system unit, and the constitution of electron transfer chain at the late growth stage of the variety. It could also promote the expression of the enzymes related to the energy synthesis and growth in inferior grains. High nitrogen fertilization level was not beneficial to the synthesis of starch in superior grain, but sufficient nitrogen supply was still important for the substance accumulation and metabolism. Therefore, rational nitrogen fertilization could increase the photosynthesis rate of flag leaves, enhance the source function, delay the functional early ageing, and promote the grain-filling at late growth stage.

  7. Impact of Surface Chemistry on Grain Boundary Induced Intrinsic Stress Evolution during Polycrystalline Thin Film Growth

    Science.gov (United States)

    Qi, Y.; Sheldon, B. W.; Guo, H.; Xiao, X.; Kothari, A. K.

    2009-02-01

    First principles calculations were integrated with cohesive zone and growth chemistry models to demonstrate that adsorbed species can significantly alter stresses associated with grain boundary formation during polycrystalline film growth. Using diamond growth as an example, the results show that lower substrate temperatures increase the hydrogen content at the surface, which reduces tensile stress, widens the grain boundary separations, and permits additional atom insertions that can induce compressive stress. More generally, this work demonstrates that surface heteroatoms can lead to behavior which is not readily described by existing models of intrinsic stress evolution.

  8. Watching the growth of bulk grains during recrystallization of deformed metals

    DEFF Research Database (Denmark)

    Schmidt, Søren; Fæster Nielsen, Søren; Gundlach, C.;

    2004-01-01

    We observed the in situ growth of a grain during recrystallization in the bulk of a deformed sample. We used the three-dimensional x-ray diffraction microscope located at the European Synchrotron Radiation Facility in Grenoble, France. The results showed a very heterogeneous growth pattern...

  9. Microstructure and mechanical strength of near- and sub-micrometre grain size copper prepared by spark plasma sintering

    DEFF Research Database (Denmark)

    Zhu, K. N.; Godfrey, A.; Hansen, Niels

    2017-01-01

    Spark plasma sintering (SPS) has been used to prepare fully dense samples of copper in a fully recrystallized condition with grain sizes in the near- and sub-micrometre regime. Two synthesis routes have been investigated to achieve grain size control: (i) SPS at different temperatures from 800 to...... been probed using hardness measurements and tensile testing, revealing an enhanced strength for samples with grain sizes less than ≈ 1 μm....

  10. Phase field modelling of stressed grain growth: Analytical study and the effect of microstructural length scale

    Energy Technology Data Exchange (ETDEWEB)

    Jamshidian, M., E-mail: mostafa.jamshidian@gmail.com [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); Rabczuk, T., E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, Seoul (Korea, Republic of)

    2014-03-15

    We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale.

  11. Simplifying the Preparation of Pollen Grains for MALDI-TOF MS Classification

    Science.gov (United States)

    Lauer, Franziska; Seifert, Stephan; Kneipp, Janina; Weidner, Steffen M.

    2017-01-01

    Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is a well-implemented analytical technique for the investigation of complex biological samples. In MS, the sample preparation strategy is decisive for the success of the measurements. Here, sample preparation processes and target materials for the investigation of different pollen grains are compared. A reduced and optimized sample preparation process prior to MALDI-TOF measurement is presented using conductive carbon tape as target. The application of conductive tape yields in enhanced absolute signal intensities and mass spectral pattern information, which leads to a clear separation in subsequent pattern analysis. The results will be used to improve the taxonomic differentiation and identification, and might be useful for the development of a simple routine method to identify pollen based on mass spectrometry. PMID:28273807

  12. Modelling of Grain Growth Kinetics in Porous Ceramic Materials under Normal and Irradiation Conditions

    Directory of Open Access Journals (Sweden)

    Mikhail S. Veshchunov

    2009-09-01

    Full Text Available Effect of porosity on grain growth is both the most frequent and technologically important situation encountered in ceramic materials. Generally this effect occurs during sintering, however, for nuclear fuels it also becomes very important under reactor irradiation conditions. In these cases pores and gas bubbles attached to the grain boundaries migrate along with the boundaries, in some circumstances giving a boundary migration controlled by the movement, coalescence and/or sintering of these particles. New mechanisms of intergranular bubble and pore migration which control the mobility of the grain boundary under normal and irradiation conditions are reviewed in this paper.

  13. Multiple seeding for the growth of bulk GdBCO-Ag superconductors with single grain behaviour

    Science.gov (United States)

    Shi, Y.; Durrell, J. H.; Dennis, A. R.; Huang, K.; Namburi, D. K.; Zhou, D.; Cardwell, D. A.

    2017-01-01

    Rare earth-barium-copper oxide bulk superconductors fabricated in large or complicated geometries are required for a variety of engineering applications. Initiating crystal growth from multiple seeds reduces the time taken to melt-process individual samples and can reduce the problem of poor crystal texture away from the seed. Grain boundaries between regions of independent crystal growth can reduce significantly the flow of current due to crystallographic misalignment and the agglomeration of impurity phases. Enhanced supercurrent flow at such boundaries has been achieved by minimising the depth of the boundary between A growth sectors generated during the melt growth process by reducing second phase agglomerations and by a new technique for initiating crystal growth that minimises the misalignment between different growth regions. The trapped magnetic fields measured for the resulting samples exhibit a single trapped field peak indicating they are equivalent to conventional single grains.

  14. Preparation and Structural Characterization of Superionic Conductor RbAg4I5 Crystalline Grain Film

    Science.gov (United States)

    Cao, Yang; Sun, Hong-San; Sun, Jia-Lin; Tian, Guang-Yan; Xing, Zhi; Guo, Ji-Hua

    2003-05-01

    Superionic conductor RbAg4I5 crystalline grain films were prepared by vacuum thermal evaporation on NaCl crystalline substrates. The surface morphology, microstructure and the electronic energy states of the films were examined by atomic force microscopy, transmission-electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. The results show that the obtained RbAg4I5 layer has an epitaxial film of perfect crystalline structure, and the unit cell of crystalline grain RbAg4I5 films belongs to cubic crystal system. The principal x-ray diffraction peaks at d = 3.7447 and 1.8733 Å are related to the structure of ternary compound RbAg4I5 films.

  15. 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

    2017-02-01

    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.

  16. Isothermal grain growth of reactive spray formed 7075 alloys in semi-solid state

    Institute of Scientific and Technical Information of China (English)

    Huimin Liu; Hua Cui; Bin Yang; Jishan Zhang

    2004-01-01

    The grain growth behavior in reactive spray formed 7075+2.91vol%TiC Al alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. The effects of in-situ TiC particles on the microstructure of spray formed 7075 Al alloy were also investigated. The specimens were heat-treated isothermally at various temperatures between the solidus and liquidus of 7075 Al alloy for times in the range of 10-60 min, then quenched in water. The microstructure of reheated specimens was characterized using scanning electron microscopy and optical microscopy. The grain size was measured using a mean linear intercept method.Results show that the in-situ TiC particles can effectively retard grain growth and refine the grain at a limited size. The grain growth exponent in Arrhenius equation increases from 2 to 3, which indicates that the in-situ TiC particles have the significant pinning effect on grain coarsening in the semi-solid state.

  17. Austenite grain growth and microstructure control in simulated heat affected zones of microalloyed HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei [Department of Machine Tools and Factory Management, Technical University of Berlin, Pascalstraße 8 – 9, 10587, Berlin (Germany); Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin (Germany); Kannengiesser, Thomas [Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin (Germany); Institute of Materials and Joining Technology, Otto von Guericke University Magdeburg, Universitetsplatz 2, 39106, Magdeburg (Germany)

    2014-09-08

    The roles of microalloying niobium, titanium and vanadium for controlling austenite grain growth, microstructure evolution and hardness were investigated at different simulated heat affected zones (HAZ) for high strength low alloy (HSLA) S690QL steel. High resolution FEG-SEM has been used to characterize fine bainitic ferrite, martensite and nanosized second phases at simulated coarse and fine grain HAZs. It was found that for Ti bearing steel (Ti/N ratio is 2) austenite grain had the slowest growth rate due to the presence of most stable TiN. The fine cuboidal particles promoted intragranular acicular ferrite (IGF) formation. Nb bearing steel exhibited relatively weaker grain growth retardation compared with titanium bearing steels and a mixed microstructure of bainite and martensite was present for all simulated HAZs. IGF existed at coarse grain HAZ of Ti+V bearing steel but it was totally replaced by bainite at fine grain HAZs. Hardness result was closely related to the morphology of bainitic ferrite, intragranular ferrite and second phases within ferrite. The microstructure and hardness results of different simulated HAZs were in good agreement with welded experimental results.

  18. Study on growth of coarse grains of diamond with high quality under HPHT

    Institute of Scientific and Technical Information of China (English)

    ZHOU ShengGuo; ZANG ChuanYi; MA HongAn; LI XiaoLei; ZHANG HeMin; JIA XiaoPeng

    2009-01-01

    The growth of coarse grains of diamond was observed with graphite as carbon source and Fe80Ni20 alloy powder as catalyst at HPHT in a China-type SPD 6x1670T cubic high-pressure apparatus with highly exact control system. To synthesize coarse grains of diamond crystal with high quality, ad-vanced indirect heat assembly, powder catalyst technology and catalyst with optimal granularity were used. Especially the nucleation of diamond and the growth rate were strictly controlled by the opti-mized synthesis craft. At last, diamond crystals (about 0.85 mm) in the perfect hex-octahedron shape were successfully synthesized at ~5.4 Gpa and ~1360℃ in 60 min. The characteristic of crystal growth with powder catalyst technology under HPHT was discussed. The results and techniques might be useful for production of coarse grains of diamond.

  19. On the texture and grain growth in hot-deformed and annealed WE54 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Azzeddine, Hiba; Bradai, Djamel [USTHB, Algiers (Algeria). Faculty of Physics

    2012-11-15

    A WE54 (Mg-Y-Nd-Zr) magnesium alloy was subjected to uniaxial and plane strain compression at two temperatures (300 and 400 C) and two strain rates (10{sup -4} and 10{sup -2} s{sup -1}). This processing resulted in a relative weakening of the initial strong basal texture of the as-received material. Contrarily to the conventional AZ31 alloy, the deformation texture was more or less insensitive to the processing parameters but depended strongly on the hot deformation type. Annealing treatments at 450 C up to 7 days resulted in normal grain growth. The grain growth annealing caused dissolution of the precipitates that had developed during hot deformation at 300 C. The grain growth kinetics can be described by D{sup n} = D{sub R}{sup n} + kt, where n was found to range between 6 and 11. A net randomization of the texture was evidenced for all the deformation conditions. (orig.)

  20. Silicon improves rice grain yield and photosynthesis specifically when supplied during the reproductive growth stage.

    Science.gov (United States)

    Lavinsky, Alyne O; Detmann, Kelly C; Reis, Josimar V; Ávila, Rodrigo T; Sanglard, Matheus L; Pereira, Lucas F; Sanglard, Lílian M V P; Rodrigues, Fabrício A; Araújo, Wagner L; DaMatta, Fábio M

    2016-11-01

    Silicon (Si) has been recognized as a beneficial element to improve rice (Oryza sativa L.) grain yield. Despite some evidence suggesting that this positive effect is observed when Si is supplied along the reproductive growth stage (from panicle initiation to heading), it remains unclear whether its supplementation during distinct growth phases can differentially impact physiological aspects of rice and its yield and the underlying mechanisms. Here, we investigated the effects of additions/removals of Si at different growth stages and their impacts on rice yield components, photosynthetic performance, and expression of genes (Lsi1, Lsi2 and Lsi6) involved in Si distribution within rice shoots. Positive effects of Si on rice production and photosynthesis were manifested when it was specifically supplied during the reproductive growth stage, as demonstrated by: (1) a high crop yield associated with higher grain number and higher 1000-grain weight, whereas the leaf area and whole-plant biomass remained unchanged; (2) an increased sink strength which, in turn, exerted a feed-forward effect on photosynthesis that was coupled with increases in both stomatal conductance and biochemical capacity to fix CO2; (3) higher Si amounts in the developing panicles (and grain husks) in good agreement with a remarkable up-regulation of Lsi6 (and to a lesser extent Lsi1). We suggest that proper levels of Si in these reproductive structures seem to play an as yet unidentified role culminating with higher grain number and size.

  1. Influence of Different Growth Conditions on the Kefir Grains Production, used in the Kefiran Synthesis

    Directory of Open Access Journals (Sweden)

    Carmen Rodica Pop

    2014-11-01

    Full Text Available The purpose of this study was to optimize the kefir grains biomass production, using milk as culture media. The kefir grains were cultured at different changed conditions (temperature, time, shaker rotating speed, culture media supplemented to evaluate their effects. Results showed that optimal culture conditions were using the organic skim milk, incubated at 25°C for 24 hours with a rotation rate of 125 rpm. According to results, the growth rate was 38.9 g/L for 24 h, at 25°C using the organic milk - OSM, 36.87 g/L during 24 hours, optimal time for propagation process gave 37.93 g/L kefir grains biomass when the effect of temperature level was tested. The homogenization of medium with shaker rotating induced a greater growth rate, it was obtained 38.9 g/L for 24 h, at 25°C using rotation rate at 125 rpm. The growing medium (conventional milk supplemented with different minerals and vitamins may lead to improve the growth conditions of kefir grains biomass. The optimization of the growth environment is very important for achieving the maximum production of kefir grains biomass, substrate necessary to obtain the polysaccharide kefiran

  2. Synchrotron characterization of nanograined UO2 grain growth

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Kun [Argonne National Lab. (ANL), Argonne, IL (United States); Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Yun, Di [Argonne National Lab. (ANL), Argonne, IL (United States); Jamison, Laura M. [Argonne National Lab. (ANL), Argonne, IL (United States); Lian, Jie [Rensselaer Polytechnic Inst., Troy, NY (United States); Yao, Tiankei [Rensselaer Polytechnic Inst., Troy, NY (United States)

    2015-09-30

    This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL) and aims at providing experimental data for the validation of the mesoscale simulation code MARMOT. MARMOT is a mesoscale multiphysics code that predicts the coevolution of microstructure and properties within reactor fuel during its lifetime in the reactor. It is an important component of the Moose-Bison-Marmot (MBM) code suite that has been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. In order to ensure the accuracy of the microstructure based materials models being developed within the MARMOT code, extensive validation efforts must be carried out. In this report, we summarize our preliminary synchrotron radiation experiments at APS to determine the grain size of nanograin UO2. The methodology and experimental setup developed in this experiment can directly apply to the proposed in-situ grain growth measurements. The investigation of the grain growth kinetics was conducted based on isothermal annealing and grain growth characterization as functions of duration and temperature. The kinetic parameters such as activation energy for grain growth for UO2 with different stoichiometry are obtained and compared with molecular dynamics (MD) simulations.

  3. Grain Growth Kinetics of BaTiO3 Nanocrystals During Calcining Process

    Science.gov (United States)

    Song, Xiao-lan; He, Xi; Yang, Hai-ping; Qu, Yi-xin; Qiu, Guan-zhou

    2008-06-01

    BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate (Ba(CH3COO)2) and tetra-butyl titanate (Ti(OC4H9)4) as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD) and transmission electron microscope (TEM). The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

  4. Grain Growth Kinetics of BaTiO3 Nanocrystals During Calcining Process

    Institute of Scientific and Technical Information of China (English)

    Xiao-lan Song; Xi He; Hai-ping Yang; Yi-xin Qu; Guan-zhou Qiu

    2008-01-01

    BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate (Ba(CH3COO)2) and tetra- butyl titanate (Ti(OC4H9)4) as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD) and transmis- sion electron microscope (TEM). The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

  5. Grain Growth and Bubble Evolution in U-Mo Alloy by Multiscale Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Zhi-Gang; Liang, Linyun; Kim, Yeon Soo; Wiencek, Tom; Hofman, Gerard; Anitescu, Mihai; Yacout, Abdellatif M.

    2015-01-01

    Increased grain size in U-Mo dispersion fuel is believed to affect the fuel swelling at high fission density. In this work, a multiscale simulation approach combining first-principles calculation and phase-field modeling is used to investigate the grain growth behavior in U-Mo alloys. The material properties of U-Mo alloys predicted by first-principles calculations are incorporated into the mesoscale phase-field models to study the effect of annealing temperature, annealing time and the initial grain structures of fuel particles on the grain growth. The grain growth rate is evaluated and compared with experiment. Meanwhile, the gas bubble evolution kinetics in irradiated U-Mo alloy fuels is investigated to understand its effect on fuel swelling. We systematically examine the effect of Xe, vacancy, and SIA concentration, fission defect generation, and elastic interaction on the growth kinetics of gas bubble. The bubble size distribution and swelling of U-Mo are simulated and compared to experimental measurements.

  6. Anisotropic grain growth and modification of 'frozen texture' in the lithospheric mantle

    Science.gov (United States)

    Boneh, Yuval; Wallis, David; Hansen, Lars; Krawczynski, Mike; Skemer, Philip

    2017-04-01

    Seismic anisotropy is widely observed in both the lithospheric and asthenospheric upper mantle, and is mainly caused by flow-induced alignment of anisotropic olivine crystals. Crystallographic preferred orientation (CPO) in the asthenosphere is thought to reflect the dynamics of current mantle flow. In contrast, the lithosphere is relatively viscous, and, it is assumed that texture in the lithosphere retains a memory of past flow (e.g., lithospheric mantle in an oceanic basin preserves texture that originated from corner flow at the mid-oceanic-ridge). Although the viscosity of the lithosphere is high in comparison to the asthenosphere, temperatures are high enough that non-deformational, microstructural processes may still be significant for texture evolution. Here we use an experimental approach to simulate a textured mantle annealed under high temperature, high pressure, and hydrostatic conditions, in order to investigate whether microstructural evolution due to static annealing could modify texture in the lithospheric mantle. Starting material for the experiments was a synthetic Fo50 olivine aggregate that was previously deformed in torsion (Hansen et al., 2016) to shear strains up to 10. The sample has a mean grain-size of 15 microns and a narrow, unimodal grain-size distribution, high dislocation-densities, and exhibits a strong A-type CPO. Sub-samples of the deformed specimen were annealed under hydrostatic conditions using a piston cylinder apparatus at T = 1250° C, P = 1 GPa for up to one week. After annealing, the samples were cut into thin sections and the crystal orientations were measured by electron backscatter diffraction (EBSD). The samples show clear evidence for abnormal grain growth due to annealing (with maximum grain sizes of 1 mm). The abnormally large grains grew at the expense of the smaller matrix grains, and grain-size distributions became distinctly bimodal. The small grains not consumed by abnormal grain growth have similar CPO strength

  7. Effect of Second Phase Particles on Grain Growth for Nanocrystalline AZ31 Mg Alloy by Phase Field Methods

    Directory of Open Access Journals (Sweden)

    Wu Yan

    2015-01-01

    Full Text Available The grain growth of nanocrystalline AZ31 magnesium alloy containing spherical particles with different sizes is simulated by phase field methods. It is shown that the role of pinning effect of the second phase particles during grain growth is interesting. There is a critical particle size to affect the grain growth in nanostructure. If the size of particles is lower than the critical value, the effect of pinning for grain growth will be increased with further decreasing the size. If the size is larger than the critical value, the particles nearly have no pinning effects. The critical value is 200 nm when the content of particles is 10%. It is found that the grain growth exponents in kinetic equation decrease when the sizes of particles increase in nanostructure with the same volume fraction of the particles, and the pinning effect of particles on the grain growth is decreased as well.

  8. Influence of additives on anisotropic grain growth in silicon nitride ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Becher, P.F. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)]. E-mail: becherpf@ornl.gov; Painter, G.S. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Shibata, N. [Institute for Engineering Innovation, University of Tokyo, Tokyo (Japan); Satet, R.L. [Institute for Ceramics in Mechanical Engineering, University of Karlsruhe, Karlsruhe (Germany); Hoffmann, M.J. [Institute for Ceramics in Mechanical Engineering, University of Karlsruhe, Karlsruhe (Germany); Pennycook, S.J. [Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2006-04-25

    Tailoring microstructure and composition are critical components for obtaining high-performance silicon nitride (Si{sub 3}N{sub 4}) ceramics. Anisotropic growth behavior of Si{sub 3}N{sub 4} grains can be used to form very elongated grains, which serve to reinforce the matrix analogous to whisker-reinforcement of ceramics. The Si{sub 3}N{sub 4} grain morphology is known to be very sensitive to the particular additive used, especially in the case of the oxides of the rare earths (RE) and Group III elements. However, the atomistic mechanisms by which this occurs has not been understood until now. A first-principles model, the differential binding energy, has been developed to characterize the competition between RE and Si for migrating to the {beta}-Si{sub 3}N{sub 4} grain surfaces. The theory predicts that, of the RE, La should have the strongest and Lu the weakest preferential segregation to the grain surfaces. Additional calculations define the adsorption sites and their binding strengths for each of the REs on the prismatic plane of the Si{sub 3}N{sub 4} grains. These predictions are confirmed by unique atomic-resolution images obtained by aberration-corrected Z-contrast scanning transmission electron microscopy (STEM). The combined theoretical and STEM studies reveal that the elements that induce the greatest observed grain anisotropy are those with the strongest preferential segregation plus high binding strength to the prismatic grain surface. Advances now allow one to use first principles calculations to determine the chemical affinity and bonding of the rare earths, as well as other elements, at the grain interfaces; atomistic factors that actually control the growth anisotropy as opposed to the commonly considered ion size, which at best, only provides a trend.

  9. Grain Growth of in-situ Semi-solid TiB2/6061 Composites Prepared by Low Voltage Pulsed Magnetic Field Process%脉冲磁场下制备TiB2/6061半固态坯料的晶粒长大行为

    Institute of Scientific and Technical Information of China (English)

    张磊; 袁秀妹; 尧军平

    2013-01-01

    The semi-solid TiB2/6061 composites were prepared by low voltage pulsed magnetic field process,which was remelted partially at 600C for 5,10,20 and 30 min,respectively,and then was quenched in the water to reserve semi-solid structure.Finally,the effects of in-situ TiB2 particles on the microstructure of composites were investigated by the optical microscope and graphical analyzer.The experimental results show that in-situ TiB2 particles not only can obviously refine and spheroidize the ascast microstructure of semi-solid TiB2/6061 composites,but also inhibit evidently grain growth by pinning effect during reheating.At the same conditions,the coarsening rate of the specimens with in-situ TiB2 particulates addition is significantly lower than that in the specimens without TiB2 particulates addition,exhibiting a higher thermal stability than the 6061 matrix alloy,and more suitable for semi-solid thixo-forming process.%在原位TiB2/6061复合材料的凝固过程中施加低压脉冲磁场处理,制备了半固态坯料.在600℃部分重熔并分别保温5、10、20和30 min,淬火固定半固态组织,利用光学显微镜和图像分析仪观察并分析其凝固组织,主要研究了原位TiB2颗粒对晶粒长大行为的影响.结果表明,原位TiB2颗粒不仅对复合材料半固态坯料组织产生细化和球化作用,在部分重熔过程中对晶粒长大行为还具有显著抑制作用.在相同的加热条件下,复合材料的晶粒长大速率要明显低于基体合金,表现出更高的热稳定性,使得其更适合半固态触变成形.

  10. Giant secondary grain growth in Cu films on sapphire

    OpenAIRE

    Miller, David L.; Keller, Mark W.; Shaw, Justin M.; Katherine P. Rice; Keller, Robert R.; Diederichsen, Kyle M.

    2013-01-01

    Single crystal metal films on insulating substrates are attractive for microelectronics and other applications, but they are difficult to achieve on macroscopic length scales. The conventional approach to obtaining such films is epitaxial growth at high temperature using slow deposition in ultrahigh vacuum conditions. Here we describe a different approach that is both simpler to implement and produces superior results: sputter deposition at modest temperatures followed by annealing to induce ...

  11. EFFECT OF GROWTH REGULATORS ON MAIZE GRAIN YIELDS AND ITS WATER CONTENT AT HARVESTING

    OpenAIRE

    2015-01-01

    The results of three-year studies devoted to the effect of pre-sowing seeds treatment with growth regulators on grain yielding and pre-sowing water content in grain are submitted. The object of studies was the ROSS-140CB and Obsky-140CB corn hybrids. A day before sowing the seeds were treated with the following growth regulators: Lignogumat AM, Gumi-20, Mival-Agro, Krezatsin, Novosil, Immunocitovit, Phytosporin and Ribav-Extra. The total amount of the treatment solution used was 10-20 l per o...

  12. Numerical Simulation of Solidification Microstructure and Effects of Phase-field Parameters on Grain Growth Morphologies

    Institute of Scientific and Technical Information of China (English)

    Jingfeng LIU; Ruixiang LIU; Liliang CHEN

    2005-01-01

    By a simple phase field model, a series of numerical simulations of solidification microstructure was performed to show a rich variety of dendritic patterns. At the same time, the relation between the morphology of grain growth and some parameters including the strength of anisotropy, dimensionless latent heat and the size of initial solid zone was studied. It is for the first time that patterns of grain growth were associated with the size of initial solid zone,which is an interesting issue. The possible reason for this may be that variation in the size of initial solid zone may bring about fluctuation of the interface energy, making the interface unstable.

  13. Room-Temperature Curing and Grain Growth at High Humidity in Conductive Adhesives with Ultra-Low Silver Content

    Science.gov (United States)

    Pettersen, Sigurd R.; Redford, Keith; Njagi, John; Kristiansen, Helge; Helland, Susanne; Kalland, Erik; Goia, Dan V.; Zhang, Zhiliang; He, Jianying

    2017-02-01

    Isotropic conductive adhesives (ICAs) are alternatives to metallic solders as interconnects in solar modules and electronic devices, but normally require silver contents >25 vol.% and elevated curing temperatures to achieve reasonable conductivity. In this work, ICAs are prepared with a silver content of 1.0 vol.% by using polymer spheres coated with nanograined silver thin films as filler particles. In contrast to conventional ICAs, there are no organic lubricants on the silver surfaces to obstruct the formation of metallic contacts, and conductivity is achieved even when the adhesive is cured at room temperature. When exposed to long-term storage at 85°C and 85% relative humidity, the silver films undergo significant grain growth, evidenced by field-emission scanning electron microscopy observation of ion-milled cross-sections and x-ray diffraction. This has a positive effect on the electrical conductivity of the ICA through the widening of metallic contacts and decreased scattering of electrons at grain boundaries, and is explained by an electrochemical Ostwald ripening process. The effects of decoupling heat and humidity is investigated by storage at either 85°C or immersion in water. It is shown that the level of grain growth during the various post-curing treatments is dependent on the initial curing temperature.

  14. Zebra pattern in rocks as a function of grain growth affected by second-phase particles

    Directory of Open Access Journals (Sweden)

    Ulrich eKelka

    2015-09-01

    Full Text Available In this communication we present a simple microdynamic model which can explain the beginning of the zebra pattern formation in rocks. The two dimensional model consists of two main processes, mineral replacement along a reaction front, and grain boundary migration affected by impurities. In the numerical model we assume that an initial distribution of second-phase particles is present due to sedimentary layering. The reaction front percolates the model and redistributes second-phase particles by shifting them until the front is saturated and drops the particles again. This produces and enhances initial layering. Grain growth is hindered in layers with high second-phase particle concentrations whereas layers with low concentrations coarsen. Due to the grain growth activity in layers with low second-phase particle concentrations these impurities are collected at grain boundaries and the crystals become very clean. Therefore the white layers in the pattern contain large grains with low concentration of second-phase particles, whereas the dark layers contain small grains with a large second-phase particle concentration.

  15. Top seeded melt growth of Gd-Ba-Cu-O single grain superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Cardwell, D A; Shi, Y-H; Pathak, S K; Dennis, A R [Superconductivity Group, Engineering Department, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Hari Babu, N [Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University, West London UB8 3PH (United Kingdom); Iida, K [Leibniz Institute for Solid State and Materials Research Dresden (IFW)-Dresden, 01069 Dresden (Germany)

    2010-03-15

    Top seeded melt growth (TSMG) has been used extensively to fabricate large, single grain Y-Ba-Cu-O (YBCO) bulk superconductors that can trap large magnetic fields. The TSMG method is relatively economical and has enabled the development of batch processes for the fabrication of a large number of bulk single grain superconductors in a single furnace. In addition, the technique allows the fabrication of complex-shaped bulk samples with controlled and strongly connected grains by using a novel, multi-seeding process. A practical processing route for processing of LRE-Ba-Cu-O (where LRE represents a light rare earth element) single grain superconductors (which have superior properties to YBCO) has been developed at Cambridge over the past three years, based on the development of a generic seed of melt textured Mg-doped Nd-123 and suppression of solid solution phase formation in air by enriching the precursor composition with excess Ba. In this paper we report the successful application of a practical TSMG process in the fabrication of high performance Gd-Ba-Cu-O (GdBCO) single grain superconductor. This method has enabled the development of a batch process for GdBCO and we demonstrate for the first time the fabrication of a large number of high performance single grains of this material in a single process. Finally, we report the processing of bulk GdBCO in the form of complex geometries with controlled grain orientation for bespoke engineering applications.

  16. Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples.

    Science.gov (United States)

    Suslova, A; El-Atwani, O; Sagapuram, D; Harilal, S S; Hassanein, A

    2014-11-04

    Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER. One of the serious issues for PFCs is the high heat load during transient events such as ELMs and disruption in the reactor. Recrystallization and grain size growth in PFC materials caused by transients are undesirable changes in the material, since the isotropic microstructure developed after recrystallization exhibits a higher ductile-to-brittle transition temperature which increases with the grain size, a lower thermal shock fatigue resistance, a lower mechanical strength, and an increased surface roughening. The current work was focused on careful determination of the threshold parameters for surface recrystallization, grain growth rate, and thermal shock fatigue resistance under ELM-like transient heat events. Transient heat loads were simulated using long pulse laser beams for two different grades of ultrafine-grained tungsten. It was observed that cold rolled tungsten demonstrated better power handling capabilities and higher thermal stress fatigue resistance compared to severely deformed tungsten. Higher recrystallization threshold, slower grain growth, and lower degree of surface roughening were observed in the cold rolled tungsten.

  17. The Growth Path of Agricultural Labor Productivity in Major Grain Producing Areas

    Institute of Scientific and Technical Information of China (English)

    Ning; ZHOU; Qifeng; CUI

    2014-01-01

    The growth of agricultural labor productivity in major grain producing areas arises from the increase in production factors or improvement of efficiency,and is related to the sustainability of agricultural economic growth and national food security. We study the growth path of agricultural labor productivity in 13 major grain producing areas of China,and the analysis results show that from the relative endowments of land and labor in major grain producing areas,the growth rate of the output value per unit of labor is higher than that of the productivity per unit of land; in essence,this growth path of increasing the output value relying on increasing the production factor inputs is the reduction of labor,and the reduction of agricultural labor has a great elasticity of impact on the total value of agricultural production. In the case of stable future number of agricultural labor in China,the growth of agricultural labor productivity will be impossible to rely more on the increase in agricultural production factor inputs,and the growth path of agricultural economy still has to rely on the improvement of land productivity and take the efficiency-based path.

  18. EFFECT OF STRONTIUM OXIDE ON GRAIN GROWTH AND DENSIFICATION IN BNN SYSTEM

    Directory of Open Access Journals (Sweden)

    CHANDRA SEKHAR BEERA

    2013-02-01

    Full Text Available Grain size and density parameters have been investigated in SrO added Tungsten Bronze (TB type Ferroelectric Barium Sodium Niobate (BNN ceramic as a function of sintering time and sintering temperature. Addition of SrO has greatly improved the density of the system. The sample BNN with 3% SrO has showed above 95% of theoretical density. Scanning Electron Micrographs revealed normal grain growth in the present study. Activation energies for the formation of grain growth and densification in all the samples have been estimated and found lying in the range of 50-60 kcal/mole. The results are discussed in the light of present understanding.

  19. Grain Growth and Precipitation Behavior of Iridium Alloy DOP-26 During Long Term Aging

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Dean T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Muralidharan, Govindarajan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fox, Ethan E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cox, Victoria A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Geer, Tom [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-01

    The influence of long term aging on grain growth and precipitate sizes and spatial distribution in iridium alloy DOP-26 was studied. Samples of DOP-26 were fabricated using the new process, recrystallized for 1 hour (h) at 1375 C, then aged at either 1300, 1400, or 1500 C for times ranging from 50 to 10,000 h. Grain size measurements (vertical and horizontal mean linear intercept and horizontal and vertical projection) and analyses of iridium-thorium precipitates (size and spacing) were made on the longitudinal, transverse, and rolling surfaces of the as-recrystallized and aged specimens from which the two-dimensional spatial distribution and mean sizes of the precipitates were obtained. The results obtained from this study are intended to provide input to grain growth models.

  20. Three-dimensional investigation of grain orientation effects on void growth in commercially pure titanium

    Energy Technology Data Exchange (ETDEWEB)

    Pushkareva, Marina [Department of Mechanical Engineering, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Adrien, Jérôme; Maire, Eric [Université de Lyon, INSA-Lyon, MATEIS CNRS UMR5510, 7 Avenue Jean Capelle, F-69621 Villeurbanne (France); Segurado, Javier; Llorca, Javier [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Materials Science, Polytechnic University of Madrid, E. T. S. de Ingenieros de Caminos, 28040 Madrid (Spain); Weck, Arnaud, E-mail: aweck@uottawa.ca [Department of Mechanical Engineering, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Centre for Research in Photonics at the University of Ottawa, 800 King Edward Ave., Ottawa, ON, Canada K1N 6N5 (Canada)

    2016-08-01

    The fracture process of commercially pure titanium was visualized in model materials containing artificial holes. These model materials were fabricated using a femtosecond laser coupled with a diffusion bonding technique to obtain voids in the interior of titanium samples. Changes in void dimensions during in-situ straining were recorded in three dimensions using x-ray computed tomography. Void growth obtained experimentally was compared with the Rice and Tracey model which predicted well the average void growth. A large scatter in void growth data was explained by differences in grain orientation which was confirmed by crystal plasticity simulations. It was also shown that grain orientation has a stronger effect on void growth than intervoid spacing and material strength. Intervoid spacing, however, appears to control whether the intervoid ligament failure is ductile or brittle.

  1. MODELING NANOCRYSTALLINE GRAIN GROWTH DURING THE PULSED ELECTRODEPOSITION OF GOLD-COPPER

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, A F

    2005-10-27

    The process parameters of current density, pulse duration, and cell potential affect both the structure and composition of electrodeposits. The mechanism for nucleation and growth as determined from current transients yield relationships for nucleus density and nucleation rate. To develop an understanding of the role of the process parameters on grain size, as a design structural parameter to control strength for example, a formulation is presented to model the affects of the deposition energy on grain size and morphology. An activation energy for the deposition process is modeled that reveals different growth mechanisms, wherein nucleation and diffusion effects are each dominant as dependent upon pulse duration. A diffusion coefficient common for each of the pulsed growth modes demarcates an observed transition in growth from smooth to rough surfaces.

  2. Monte Carlo study on abnormal growth of Goss grains in Fe3%Si steel induced by second-phase particles

    Institute of Scientific and Technical Information of China (English)

    Dong-qun Xin; Cheng-xu He; Xue-hai Gong; Hao Wang; Li Meng; Guang Ma; Peng-fei Hou; Wen-kang Zhang

    2016-01-01

    The selective abnormal growth of Goss grains in magnetic sheets of Fe-3%Si (grade Hi-B) induced by second-phase particles (AlN and MnS) was studied using a modified Monte Carlo Potts model. The starting microstructures for the simulations were generated from electron backscatter diffraction (EBSD) orientation imaging maps of recrystallized samples. In the simulation, second-phase particles were assumed to be randomly distributed in the initial microstructures and the Zener drag effect of particles on Goss grain boundaries was as-sumed to be selectively invalid because of the unique properties of Goss grain boundaries. The simulation results suggest that normal growth of the matrix grains stagnates because of the pinning effect of particles on their boundaries. During the onset of abnormal grain growth, some Goss grains with concave boundaries in the initial microstructure grow fast abnormally and other Goss grains with convex boundaries shrink and eventually disappear.

  3. Monte Carlo study on abnormal growth of Goss grains in Fe-3%Si steel induced by second-phase particles

    Science.gov (United States)

    Xin, Dong-qun; He, Cheng-xu; Gong, Xue-hai; Wang, Hao; Meng, Li; Ma, Guang; Hou, Peng-fei; Zhang, Wen-kang

    2016-12-01

    The selective abnormal growth of Goss grains in magnetic sheets of Fe-3%Si (grade Hi-B) induced by second-phase particles (AlN and MnS) was studied using a modified Monte Carlo Potts model. The starting microstructures for the simulations were generated from electron backscatter diffraction (EBSD) orientation imaging maps of recrystallized samples. In the simulation, second-phase particles were assumed to be randomly distributed in the initial microstructures and the Zener drag effect of particles on Goss grain boundaries was assumed to be selectively invalid because of the unique properties of Goss grain boundaries. The simulation results suggest that normal growth of the matrix grains stagnates because of the pinning effect of particles on their boundaries. During the onset of abnormal grain growth, some Goss grains with concave boundaries in the initial microstructure grow fast abnormally and other Goss grains with convex boundaries shrink and eventually disappear.

  4. Grain growth across protoplanetary discs: 10-micron silicate feature versus millimetre slope

    CERN Document Server

    Lommen, Dave J P; Wright, Chris M; Maddison, Sarah T; Min, Michiel; Wilner, David J; Salter, Demerese M; van Langevelde, Huib Jan; Bourke, Tyler L; van der Burg, Remco F J; Blake, Geoffrey A

    2010-01-01

    Young stars are formed within dusty discs. The grains in the disc are originally of the same size as interstellar dust. Models predict that these grains will grow in size through coagulation. Observations of the silicate features at micron wavelengths are consistent with growth to micron sizes whereas the slope of the SED at longer wavelengths traces growth up to mm sizes. We here look for a correlation between these two grain growth indicators. A large sample of T-Tauri and Herbig-Ae/Be stars was observed with the Spitzer Space Telescope at 5-13 micron; a subsample was observed at mm wavelengths. We complement this subsample with data from the literature to maximise the overlap between micron and mm observations and search for correlations. Synthetic spectra are produced to determine which processes may produce the dust evolution. Dust disc masses in the range <1 to 7 x 10^-4 MSun are obtained. Most sources have a mm spectral slope consistent with grain growth. There is a tentative correlation between the...

  5. Grain growth signatures in the protoplanetary discs of Chamaeleon and Lupus

    CERN Document Server

    Ubach, Catarina; Wright, Christopher M; Wilner, David J; Lommen, Dave J P; Koribalski, Baerbel

    2012-01-01

    We present ATCA results of a 3 and 7 mm continuum survey of 20 T Tauri stars in the Chamaeleon and Lupus star forming regions. This survey aims to identify protoplanetary discs with signs of grain growth. We detected 90% of the sources at 3 and 7 mm, and determined the spectral slopes, dust opacity indices and dust disc masses. We also present temporal monitoring results of a small sub-set of sources at 7, 15 mm and 3+6 cm to investigate grain growth to cm sizes and constrain emission mechanisms in these sources. Additionally, we investigated the potential correlation between grain growth signatures in the infrared (10 \\mu m silicate feature) and millimetre (1-3 mm spectral slope, {\\alpha}). Eleven sources at 3 and 7 mm have dominant thermal dust emission up to 7 mm, with 7 of these having a 1-3 mm dust opacity index less than unity, suggesting grain growth up to at least mm sizes. The Chamaeleon sources observed at 15 mm and beyond show the presence of excess emission from an ionised wind and/or chromo- sphe...

  6. Study of microstructure and electrical properties of bulk YBCO prepared by melt textured growth technique

    Energy Technology Data Exchange (ETDEWEB)

    Gonal, M. R.; Krishnan, Madangopal [Glass and Advanced Materials Division, Bhabha Atomic Research Centre, Mumbai, INDIA 400 085 (India); Tewari, R. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai, INDIA 400 085 (India); Tyagi, A. K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai, INDIA 400 085 (India); Gyore, A.; Vajda, I. [Department of Electric Power Engineering, Budapest Univ. of Technology & Economics, Budapest (Hungary)

    2015-06-24

    Bulk YBCO components were prepared using Melt Texture Growth (MTG) technique. Components were fabricated using MTG by addition of Y{sub 2}BaCuO{sub 5} (Y211) and Ag to YBCO, which leads to improved grain size without affecting superconducting properties. Green compacts prepared by cold isostatic pressing were pre-sintered at 930°C before subjecting melt texturing. Cooling rates lower than 1 °C.h{sup −1} was used, in between (peritectic) temperature of about 995 and 1025°C, to obtain large grained components. Microstructure studies in details were carried out by Scanning Electron Microscope (SEM), Electron Probe Micro Analysis (EPMA), Orientation Imaging Microscope (OIM) and TEM correlated with electrical properties like Critical current density (J{sub c})

  7. Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

    Directory of Open Access Journals (Sweden)

    Yuan Jin

    2015-12-01

    Full Text Available Grain growth experiments were performed on Inconel™ 718 to investigate the possible correlation of the annealing twin density with grain size and with annealing temperature. Those experiments were conducted at different temperatures in the δ supersolvus domain and under such conditions that only capillarity forces were involved in the grain boundary migration process. In the investigated range, there is a strong inverse correlation of the twin density with the average grain size. On the other hand, the twin density at a given average grain size is not sensitive to annealing temperature. Consistent with previous results for pure nickel, the twin density evolution in Inconel™ 718 is likely to be mainly controlled by the propagation of the pre-existing twins of the growing grains; i.e., the largest ones of the initial microstructure. Almost no new twin boundaries are created during the grain growth process itself. Therefore, the twin density at a given average grain size is mainly dependent on the twin density in the largest grains of the initial microstructure and independent of the temperature at which grains grow. Based on the observations, a mean field model is proposed to predict annealing twin density as a function of grain size during grain growth.

  8. Grain growth of nanocrystalline 3C-SiC under Au ion irradiation at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Limin; Jiang, Weilin; Dissanayake, Amila C.; Varga, Tamas; Zhang, Jiandong; Zhu, Zihua; Hu, Dehong; Wang, Haiyan; Henager, Charles H.; Wang, Tieshan

    2016-01-09

    Nanocrystalline silicon carbide (SiC) represents an excellent model system for a fundamental study of interfacial (grain boundary) processes under nuclear radiation, which are critical to the understanding of the response of nanostructured materials to high-dose irradiation. This study reports on a comparison of irradiation effects in cubic phase SiC (3C-SiC) grains of a few nanometers in size and single-crystal 3C-SiC films under identical Au ion irradiation to a range of doses at 700 K. In contrast to the latter, in which lattice disorder is accumulated to a saturation level without full amorphization, the average grain size of the former increases with dose following a power-law trend. In addition to coalescence, the grain grows through atomic jumps and mass transport, where irradiation induced vacancies at grain boundaries assist the processes. It is found that a higher irradiation temperature leads to slower grain growth and a faster approach to a saturation size of SiC nanograins. The results could potentially have a positive impact on structural components of advanced nuclear energy systems.

  9. Centre seeded infiltration and growth process for fabrication of large grain bulk YBCO/Ag superconducting composites

    Science.gov (United States)

    Parthasarathy, R.; Seshubai, V.

    2012-06-01

    We report the fabrication of a large grain bulk YBCO/Ag superconductor using a novel technique which we call Centre Seeded Infiltration and Growth Process (CSIGP). Using this technique, it has been made possible to get bulk YBCO/Ag composite sample with uniform grain growth textured along the c-axis. The resulting large grain sample has been found to have high critical current densities up to large magnetic fields. We correlate the improved superconducting and magnetic properties to the modified grain growth conditions employed in this fabrication technique.

  10. Anomalous grain growth in nanocrystalline Fe73.5Cu1Nb3Su13.5B9 alloys

    DEFF Research Database (Denmark)

    Jiang, Jianzhong

    1997-01-01

    The grain growth of the FeSi phase during the crystallization process of the amorphous Fe73.5Cu1Nb3Si13.5B9 alloy was studied using transmission electron microscopy and x-ray diffractometry. An anomalous grain growth behaviour of the FeSi phase in the samples annealed in temperature range from 74...

  11. Maize development and grain quality are differentially affected by mycorrhizal fungi and a growth-promoting pseudomonad in the field.

    Science.gov (United States)

    Berta, Graziella; Copetta, Andrea; Gamalero, Elisa; Bona, Elisa; Cesaro, Patrizia; Scarafoni, Alessio; D'Agostino, Giovanni

    2014-04-01

    Arbuscular mycorrhizal (AM) fungi and plant growth-promoting bacteria (PGPB) can increase the growth and yield of major crops, and improve the quality of fruits and leaves. However, little is known about their impact on seed composition. Plants were inoculated with AM fungi and/or the bacterial strain Pseudomonas fluorescens Pf4 and harvested after 7 months of growth in open-field conditions. Plant growth parameters were measured (biomass, length and circumference of spikes, number of grains per cob, grain yield, and grain size) and protein, lipid, and starch content in grains were determined. Plant growth and yield were increased by inoculation with the microorganisms. Moreover, spikes and grains of inoculated plants were bigger than those produced by uninoculated plants. Regarding grain composition, the bacterial strain increased grain starch content, especially the digestible components, whereas AM fungi-enhanced protein, especially zein, content. Plant inoculation with the fluorescent pseudomonad and mycorrhizal fungi resulted in additive effects on grain composition. Overall, results showed that the bacterial strain and the AM fungi promoted maize growth cultivated in field conditions and differentially affected the grain nutritional content. Consequently, targeted plant inoculation with beneficial microorganisms can lead to commodities fulfilling consumer and industrial requirements.

  12. Preparation and Structural Characterization of Superionic Conductor RbAg4I5 Crystalline Grain Film

    Institute of Scientific and Technical Information of China (English)

    曹阳; 孙红三; 孙家林; 田广彦; 邢志; 郭继华

    2003-01-01

    Superionic conductor RbAg4I5 crystalline grainfilms were prepared by vacuum thermal evaporation on NaCl crystalline substrates. The surface morphology, microstructure and the electronic energy states of the films were examined by atomic force microscopy, transmission-electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. The results show that the obtained RbAg4I5 layer has an epitaxial film of perfect crystalline structure, and the unit cell of crystalline grain RbAg4I5 films belongs to cubic crystal system. The principal x-ray diffraction peaks at d = 3.7447 and 1.8733A are related to the structure of ternary compound RbAg4I5films.

  13. Effects of Aerated Irrigation on Leaf Senescence at Late Growth Stage and Grain Yield of Rice

    Institute of Scientific and Technical Information of China (English)

    ZHU Lian-feng; Yu Sheng-miao; JIN Qian-yu

    2012-01-01

    With the japonica inbred cultivar Xiushui 09,indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials,field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf senescence at late growth stage and grain yield of rice.The dissolved oxygen concentration of aerated water evidently increased and decreased at a slow rate.The soil oxidation-reduction potential under aerated irrigation treatment was significantly higher than that of the CK,contributing to significant increases in effective panicles,seed setting rate and grain yield.In addition,the aerated irrigation improved root function,increased superoxide dismutase activity and decreased malondialdehyde content in flag leaves at post-flowering,which delayed leaf senescence process,prolonged leaf functional activity and led to enhanced grain filling.

  14. Effect of Deforming Temperature and Strain on Abnormal Grain Growth of Extruded FGH96 Superalloy

    Directory of Open Access Journals (Sweden)

    WANG Chaoyuan

    2016-10-01

    Full Text Available Based on the experiments of isothermal forging wedge-shaped samples, Deform-3D numerical simulation software was used to confirm the strain distribution in the wedge-shaped samples. The effect of deforming temperature and strain on abnormal grain growth(AGG in extruded FGH96 superalloy was examined. It is found that when the forging speed is 0.04 mm/s,the critical AGG occurring temperature is 1100℃,and the critical strain is 2%.AGG does not occur within 1000-1070℃,but still shows the feature of ‘critical strain’,and the region with strain of 5%-10% has the largest average grain size.AGG can be avoided and the uniform fine grains can be gained when the strain is not less than 15%.

  15. Effects of Rice Variety and Growth Location in Cambodia on Grain Composition and Starch Structure

    Institute of Scientific and Technical Information of China (English)

    Seila SAR; Morgan J.TIZZOTTI; Jovin HASJIM; Robert G.GILBERT

    2014-01-01

    The effects of variety and growth location on grain composition and starch structures were investigated using three rice (Oryza sativa L.) cultivars (Phka Romduol, Sen Pidao and IR66) with different amylose contents. All the three cultivars were planted in three different agro-climatic zones (Phnom Penh, Coastal and Plateau) of Cambodia. The protein content of polished grains increased when rice was planted at a location with higher average temperature, but their lipid content decreased. The amylose content and degree of branching were not greatly affected by the minor temperature differences among the growing locations. Starch fine structures characterized by the chain-length distribution were significantly different among the cultivars, but not significantly among different locations. The results suggested that protein and lipid biosyntheses were more sensitive to the environmental temperature than that of starch in rice grains.

  16. NANOCRYSTALLINE GROWTH AND GRAIN-SIZE EFFECTS IN AU-CU ELECTRODEPOSITS

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, A F; Saw, C K; Harper, J F; Vallier, R F; Ferreira, J L; Hayes, J P

    2005-02-25

    The processing-structure-property relationship is investigated for electrodeposited foils of the gold-copper alloy system. A model is presented that relates the deposition process parameters to the nanocrystalline grain size. An activation energy of 1.52 eV {center_dot} atom{sup -1} for growth is determined for a long pulse (>10 msec) mode, and is 0.16 eV {center_dot} atom{sup -1} for short pulses (<5 msec). The affect of nanocrystalline grain size on the mechanical properties is assessed using indentation measurements. A Hall-Petch type variation of the Vickers microhardness with nanocrystalline grain size (>6 nm) is observed for Au-Cu samples with 1-12 wt.% Cu as tested in cross-section. The hardness increases three-fold from a rule-of-mixtures value <1 GPa to a maximum of 2.9 GPa.

  17. Effect of solidification rate on competitive grain growth in directional solidification of a nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHOU YiZhou; SUN XiaoFeng

    2012-01-01

    The mechanism of grain structure evolution during directional solidification is a fundamental subject in material science.Within the published research there exist conflicting views on the mechanism of grain overgrowth.To study the effect of solidification rate on grain structure evolution,bi-crystals samples were produced in a nickel-base superalloy at different solidification rates.It was found that at the convergent grain boundaries those grains better aligned with respect to the heat flux more readily overgrew neighbouring grains with misaligned orientations and the effect became more pronounced as solidification rate was increased.However,at diverging grain boundaries the rate of overgrowth was invariant to the solidification rate.These experimental results were compared with models in the literature.Thus,a better insight into competitive grain growth in directional solidification processes was obtained.

  18. Computational study of textured ferroelectric polycrystals: Texture development during templated grain growth

    Science.gov (United States)

    Zhou, Jie E.; Yan, Yongke; Priya, Shashank; Wang, Yu U.

    2017-02-01

    Quantitative relationships between processing, microstructure, and properties in textured ferroelectric polycrystals and the underlying responsible mechanisms are investigated by phase field modeling and computer simulation. This study focuses on three important aspects of textured ferroelectric ceramics: (i) grain microstructure evolution during templated grain growth processing, (ii) crystallographic texture development as a function of volume fraction and seed size of the templates, and (iii) dielectric and piezoelectric properties of the obtained template-matrix composites of textured polycrystals. Findings on the first two aspects are presented here, while an accompanying paper of this work reports findings on the third aspect. In this paper, grain microstructure evolution in the polycrystalline matrix with different template volume fractions and seed sizes is simulated. To quantitatively characterize the crystallographic texture development during templated grain growth processing, a numerical algorithm is developed to compute the diffraction peak intensities and Lotgering factor of the simulated polycrystals during grain microstructure evolution. This novel approach provides a direct link between phase field simulation and diffraction experiment. This computational study clarifies the effects of the template volume fraction and template seed size on the final grain microstructure and texture. It is found that, while the degree of crystallographic texture generally increases with increasing template volume fraction, it is the average distance between template seeds that plays an important role. This finding suggests that reducing the template seed size and shortening the seed distance is an effective way to achieve higher texture at a lower template volume fraction, which is highly desired for enhancing the piezoelectric properties of ferroelectric polycrystals. The computational results are compared with complementary experiments, where good agreement is

  19. Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers.

    Science.gov (United States)

    Najmaei, Sina; Liu, Zheng; Zhou, Wu; Zou, Xiaolong; Shi, Gang; Lei, Sidong; Yakobson, Boris I; Idrobo, Juan-Carlos; Ajayan, Pulickel M; Lou, Jun

    2013-08-01

    Single-layered molybdenum disulphide with a direct bandgap is a promising two-dimensional material that goes beyond graphene for the next generation of nanoelectronics. Here, we report the controlled vapour phase synthesis of molybdenum disulphide atomic layers and elucidate a fundamental mechanism for the nucleation, growth, and grain boundary formation in its crystalline monolayers. Furthermore, a nucleation-controlled strategy is established to systematically promote the formation of large-area, single- and few-layered films. Using high-resolution electron microscopy imaging, the atomic structure and morphology of the grains and their boundaries in the polycrystalline molybdenum disulphide atomic layers are examined, and the primary mechanisms for grain boundary formation are evaluated. Grain boundaries consisting of 5- and 7- member rings are directly observed with atomic resolution, and their energy landscape is investigated via first-principles calculations. The uniformity in thickness, large grain sizes, and excellent electrical performance signify the high quality and scalable synthesis of the molybdenum disulphide atomic layers.

  20. Temperature dependent grain-size and microstrain of CdO thin films prepared by spray pyrolysis method

    Indian Academy of Sciences (India)

    B G Jeyaprakash; K Kesavan; R Ashok Kumar; S Mohan; A Amalarani

    2011-07-01

    CdO thin films on glass substrate were prepared by home built spray pyrolysis unit from aqueous solution of Cd(CH3COO)2.2H2O at different substrate temperatures. X-ray diffraction (XRD) studies indicate the formation of polycrystalline cubic CdO phase with preferential orientation along (111) plane. X-ray line broadening technique is adopted to study the effect of substrate temperature on microstructural parameters such as grain size and microstrain. Scanning electron microscopy (SEM) shows that the film prepared at 250°C consists of spherical shape grains with size in nanometer range and is comparable with the XRD studies.

  1. Investigating grain growth in disks around southern T Tauri stars at millimetre wavelengths

    CERN Document Server

    Lommen, D; Maddison, S T; Jørgensen, J K; Bourke, T L; Van Dishoeck, E F; Hughes, A; Wilner, D J; Burton, M; Van Langevelde, H J; Lommen, Dave; Wright, Chris M.; Maddison, Sarah T.; Jorgensen, Jes K.; Bourke, Tyler L.; Dishoeck, Ewine F. van; Hughes, Annie; Wilner, David J.; Burton, Michael; Langevelde, Huib Jan van

    2006-01-01

    CONTEXT - Low-mass stars form with disks in which the coagulation of grains may eventually lead to the formation of planets. It is not known when and where grain growth occurs, as models that explain the observations are often degenerate. A way to break this degeneracy is to resolve the sources under study. AIMS - To find evidence for the existence of grains of millimetre sizes in disks around in T Tauri stars, implying grain growth. METHODS - The Australia Telescope Compact Array (ATCA) was used to observe 15 southern T Tauri stars, five in the constellation Lupus and ten in Chamaeleon, at 3.3 millimetre. The five Lupus sources were also observed with the Submillimeter Array (SMA) at 1.4 millimetre. Our new data are complemented with data from the literature to determine the slopes of the spectral energy distributions in the millimetre regime. RESULTS - Ten sources were detected at better than 3sigma with the ATCA, with sigma ~1-2 mJy, and all sources that were observed with the SMA were detected at better t...

  2. Orientation-field models for polycrystalline solidification: Grain coarsening and complex growth forms

    Science.gov (United States)

    Korbuly, Bálint; Pusztai, Tamás; Tóth, Gyula I.; Henry, Hervé; Plapp, Mathis; Gránásy, László

    2017-01-01

    We compare two versions of the phase-field theory for polycrystalline solidification, both relying on the concept of orientation fields: one by Kobayashi et al. [Physica D 140 (2000) 141] [15] and the other by Henry et al. [Phys. Rev. B 86 (2012) 054117] [22]. Setting the model parameters so that the grain boundary energies and the time scale of grain growth are comparable in the two models, we first study the grain coarsening process including the limiting grain size distribution, and compare the results to those from experiments on thin films, to the models of Hillert, and Mullins, and to predictions by multiphase-field theories. Next, following earlier work by Gránásy et al. [Phys. Rev. Lett. 88 (2002) 206105; Phys. Rev. E 72 (2005) 011605] [17,21], we extend the orientation field to the liquid state, where the orientation field is made to fluctuate in time and space, and employ the model for describing of multi-dendritic solidification, and polycrystalline growth, including the formation of "dizzy" dendrites disordered via the interaction with foreign particles.

  3. Oriented grain growth and modification of 'frozen anisotropy' in the lithospheric mantle

    Science.gov (United States)

    Boneh, Yuval; Wallis, David; Hansen, Lars N.; Krawczynski, Mike J.; Skemer, Philip

    2017-09-01

    Seismic anisotropy throughout the oceanic lithosphere is often assumed to be generated by fossilized texture formed during deformation at asthenospheric temperatures close to the ridge. Here we investigate the effect of high-temperature and high-pressure static annealing on the texture of previously deformed olivine aggregates to simulate residence of deformed peridotite in the lithosphere. Our experiments indicate that the orientation and magnitude of crystallographic preferred orientation (CPO) will evolve due to the preferential growth of grains with low dislocation densities. These observations suggest that texture and stored elastic strain energy promote a style of grain growth that modifies the CPO of a deformed aggregate. We demonstrate that these microstructural changes alter the orientation distributions and magnitudes of seismic wave velocities and anisotropy. Therefore, static annealing may complicate the inference of past deformation kinematics from seismic anisotropy in the lithosphere.

  4. The role of grain boundary structure and crystal orientation on crack growth asymmetry in aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Adlakha, I. [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287 (United States); Tschopp, M.A. [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Solanki, K.N., E-mail: kiran.solanki@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287 (United States)

    2014-11-17

    Atomistic simulations have shown that the grain boundary (GB) structure affects a number of physical, mechanical, thermal, and chemical properties, which can have a profound effect on macroscopic properties of polycrystalline materials. The research objective herein is to use atomistic simulations to explore the role that GB structure and the adjacent crystallographic orientations have on the directional asymmetry of an intergranular crack (i.e. cleavage behavior is favored along one direction, while ductile behavior along the other direction of the interface) for aluminum grain boundaries. Simulation results from seven 〈110〉 symmetric tilt grain boundaries (STGBs) show that the GB structure and the associated free volume directly influence the stress–strain response, crack growth rate, and crack tip plasticity mechanisms for middle-tension (M(T)) crack propagation specimens. In particular, the structural units present within the GB promote whether a dislocation or twinning-based mechanism operates at the crack tip during intergranular fracture along certain GBs (e.g., the ‘E’ structural unit promotes twinning at the crack tip in Al). Furthermore, the crystallography of the adjacent grains, and therefore the available slip planes, can significantly affect the crack growth rates in both directions of the crack – this creates a strong directional asymmetry in the crack growth rate in the Σ11 (113) and the Σ27 (552) STGBs. Upon comparing these results with the theoretical Rice criterion, it was found that certain GBs in this study (Σ9 (221), Σ11 (332) and Σ33 (441)) show an absence of directional asymmetry in the observed crack growth behavior, in conflict with the Rice criterion. The significance of the present research is that it provides a physical basis for the role of GB character and crystallographic orientation on intergranular crack tip deformation behavior.

  5. Austenite Grain Growth and Precipitate Evolution in a Carburizing Steel with Combined Niobium and Molybdenum Additions

    Science.gov (United States)

    Enloe, Charles M.; Findley, Kip O.; Speer, John G.

    2015-11-01

    Austenite grain growth and microalloy precipitate size and composition evolution during thermal processing were investigated in a carburizing steel containing various additions of niobium and molybdenum. Molybdenum delayed the onset of abnormal austenite grain growth and reduced the coarsening of niobium-rich precipitates during isothermal soaking at 1323 K, 1373 K, and 1423 K (1050 °C, 1100 °C, and 1150 °C). Possible mechanisms for the retardation of niobium-rich precipitate coarsening in austenite due to molybdenum are considered. The amount of Nb in solution and in precipitates at 1373 K (1100 °C) did not vary over the holding times evaluated. In contrast, the amount of molybdenum in (Nb,Mo)C precipitates decreased with time, due to rejection of Mo into austenite and/or dissolution of fine Mo-rich precipitates. In hot-rolled alloys, soaking in the austenite regime resulted in coarsening of the niobium-rich precipitates at a rate that exceeded that predicted by the Lifshitz-Slyozov-Wagner relation for volume-diffusion-controlled coarsening. This behavior is attributed to an initial bimodal precipitate size distribution in hot-rolled alloys that results in accelerated coarsening rates during soaking. Modification of the initial precipitate size distribution by thermal processing significantly lowered precipitate coarsening rates during soaking and delayed the associated onset of abnormal austenite grain growth.

  6. Experimental studies of Micro- and Nano-grained UO2: Grain Growth Behavior, Sufrace Morphology, and Fracture Toughness

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Mo, Kun [Argonne National Lab. (ANL), Argonne, IL (United States); Jamison, Laura M. [Argonne National Lab. (ANL), Argonne, IL (United States); Lian, Jie [Rensselaer Polytechnic Inst., Troy, NY (United States); Yao, Tiankai [Rensselaer Polytechnic Inst., Troy, NY (United States); Bhattacharya, Sumit [Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)

    2016-01-01

    This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL) and aims at providing experimental data for the validation of the mesoscale simulation code MARMOT. MARMOT is a mesoscale multiphysics code that predicts the coevolution of microstructure and properties within reactor fuel during its lifetime in the reactor. It is an important component of the Moose-Bison-Marmot (MBM) code suite that has been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. In order to ensure the accuracy of the microstructure-based materials models being developed within the MARMOT code, extensive validation efforts must be carried out. In this report, we summarize the experimental efforts in FY16 including the following important experiments: (1) in-situ grain growth measurement of nano-grained UO2; (2) investigation of surface morphology in micrograined UO2; (3) Nano-indentation experiments on nano- and micro-grained UO2. The highlight of this year is: we have successfully demonstrated our capability to in-situ measure grain size development while maintaining the stoichiometry of nano-grained UO2 materials; the experiment is, for the first time, using synchrotron X-ray diffraction to in-situ measure grain growth behavior of UO2.

  7. Structure and strength of aluminum with sub-micrometer/micrometer grain size prepared by spark plasma sintering

    DEFF Research Database (Denmark)

    Le, G.M.; Godfrey, A.; Hansen, Niels

    2013-01-01

    A spark plasma sintering (SPS) technique has been applied to prepare fully dense Al samples from Al powder. By applying a sintering temperature of 600°C and a loading pressure of 50MPa, fully recrystallized samples of nearly 100% density with average grain sizes of 5.2μm, 1.3μm and 0.8μm have been...... the initial powder particle size. The SPS samples show higher strength than Al samples with an identical grain size prepared using thermo-mechanical processing, and a better strength-ductility combination, with the 1.3μm grain size sample showing a yield strength (σ0.2%) of 140MPa and a uniform elongation...

  8. Molecular dynamics simulations investigating consecutive nucleation, solidification and grain growth in a twelve-million-atom Fe-system

    Science.gov (United States)

    Okita, Shin; Verestek, Wolfgang; Sakane, Shinji; Takaki, Tomohiro; Ohno, Munekazu; Shibuta, Yasushi

    2017-09-01

    Continuous processes of homogeneous nucleation, solidification and grain growth are spontaneously achieved from an undercooled iron melt without any phenomenological parameter in the molecular dynamics (MD) simulation with 12 million atoms. The nucleation rate at the critical temperature is directly estimated from the atomistic configuration by cluster analysis to be of the order of 1034 m-3 s-1. Moreover, time evolution of grain size distribution during grain growth is obtained by the combination of Voronoi and cluster analyses. The grain growth exponent is estimated to be around 0.3 from the geometric average of the grain size distribution. Comprehensive understanding of kinetic properties during continuous processes is achieved in the large-scale MD simulation by utilizing the high parallel efficiency of a graphics processing unit (GPU), which is shedding light on the fundamental aspects of production processes of materials from the atomistic viewpoint.

  9. Grain Growth Behavior, Tensile Impact Ductility, and Weldability of Cerium-Doped Iridium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.

    2002-05-28

    An iridium alloy doped with small amounts of cerium and thorium is being developed as a potential replacement for the iridium-based DOP-26 alloy (doped with thorium only) that is currently used by the National Aeronautics and Space Administration (NASA) for cladding and post-impact containment of the radioactive fuel in radioisotope thermoelectric generator (RTG) heat sources which provide electric power for interplanetary spacecraft. This report summarizes results of studies conducted to date under the Iridium Alloy Characterization and Development subtask of the Radioisotope Power System Materials Production and Technology Program to characterize the properties of the iridium-based alloy (designated as DOP-40) containing both cerium and thorium. Included within this report are data on grain growth of sheet material in vacuum and low-pressure oxygen environments, grain growth in vacuum of the clad vent set cup material, weldability, and the effect of grain size and test temperature on tensile properties. Where applicable, data for the DOP-26 alloy are included for comparison. Both grain size and grain-boundary cohesion affect the ductility of iridium alloys. In this study it was found that cerium and thorium, when added together, refine grain size more effectively than when thorium is added by itself (especially at high temperatures). In addition, the effect of cerium additions on grain-boundary cohesion is similar to that of thorium. Mechanical testing at both low ({approx} 10{sup -3}s{sup -1}) and high ({approx} 10{sup -3}s{sup -1}) strain rates showed that the Ce/Th-doped alloys have tensile ductilities that are as good or better than the DOP-26 alloy. The general conclusion from these studies is that cerium can be used to replace some of the radioactive thorium currently used in DOP-26 while maintaining or improving its metallurgical properties. The current DOP-26 alloy meets all requirements for cladding the radioactive fuel in the RTG heat source, but the

  10. Grain growth kinetics in pyrolite material under lower mantle condition: Implications for the rheology of the lower mantle

    Science.gov (United States)

    Imamura, M.; Kubo, T.; Takumi, K.

    2016-12-01

    Rheology of the lower mantle largely depends on the grain-size evolution in constituent minerals. The pioneering work on the grain growth kinetics in MgSiO3 bridgmanite and MgO periclase (Yamazaki et al., 1996) has raised the problem that the grain growth rate is too slow to explain the lower-mantle viscosity. This inconsistency may arise from effects of elastic stress due to the eutectoid transformation (e.g., Solomatov et al., 2002) and it may be difficult to extrapolate the slow kinetics obtained to geological timescales. We conducted grain growth experiments in pyrolitic material at 25-27 GPa, and 1600-1950°C for 30-3000 min using Kawai-type high pressure apparatus at Kyushu University. Four phases of bridgmanite, ferro-priclase, Ca-perovskite and majoritic garnet were present in recovered samples annealed at 25 GPa. To avoid the effects of the eutectoid texture, we took the grain growth data only from the sample exhibiting relatively homogeneous equi-granular texture. That was achieved after annealing for 30 minutes at 1800-1950°C (use these grain sizes as d0), and not achieved even after annealing for 3000 minutes at 1600°C. We preliminarily obtained kinetic parameters of n=4.9 and H* 420 kJ/mol for bridgmanite, and n=4.7 and H* 160 kJ/mol for ferro-pericalse. The ratio of grain sizes of bridgmanite and ferro-periclase is almost constant during the grain growth process. These results indicate faster kinetics compared to the previous study, and can be reasonably interpreted as the grain growth occurred by Ostwald ripening. On the other hand, three phases without majoritic garnet were present at higher pressure of 27 GPa and 1800°C, in which the grain size was slightly larger probably due to the smaller proportion of the secondary phases. When extrapolating the grain growth kinetics obtained in the four phases, the grain size of bridgmanite is roughly estimated to be 4-50 µm at 800-1200°C and 200-600 µm at 1600-2000°C in 108 years. These grain sizes may

  11. Integrating statistical and ecophysiological analysis of genotype by environment interaction for grain filling of barley in Mediterranean areas. II. Grain growth

    NARCIS (Netherlands)

    Voltas, J.; Eeuwijk, van F.A.; Araus, J.L.; Romagosa, I.

    1999-01-01

    In Mediterranean areas, grain growth of temperate cereals often progresses under the harmful influence of drought and high temperature. Genotypic responses are mediated by the specific occurrence of these constraints, thus causing genotype by environment (G × E) interaction. Field experiments were c

  12. Evaluation of Grain Growth of Corn and Sorghum under K2O Application and Irrigation According

    Directory of Open Access Journals (Sweden)

    Sayed Alireza Valadabadi

    2009-08-01

    Full Text Available In this experiment, interactive effects of different potassium application and water restrict on graingrowth in Iran. The experimental unit had designed by achieved treatment in factorial on the basis completelyrandomized block design with three replicates. Certain factors including potassium and non-potassiumapplications (0 and 200 kg/ha, certain field crops (corn and sorghum and w ater supply were studied. In thisstudy crops water supply was determined by indicated irrigation conditions by keeping leaf Relative WaterContent (RW C > 95% (non-drought stress condition or irrigation conditions and drought condition by RWC= 60-70%. We noticed, however K fertilizer significantly increased the grain growth rate of plants and althoughthe non-drought stress treatment significantly increased grain growth rate. Whereas K application persist lessdamaging of drought stress result and it enabled plant to significantly grow its grain under the droughtconditions. Our finding may give applicable advice to commercial farmers and agricultural researches formanagement and concern on fertilizer strategy and carefully estim ate soil potassium supply w ithin dry or semidryareas as most challengeable issues of environmental safety.

  13. Testing the theory of grain growth and fragmentation by millimeter observations of protoplanetary disks

    CERN Document Server

    Birnstiel, T; Trotta, F; Dullemond, C P; Natta, A; Testi, L; Dominik, C; Henning, T; Ormel, C W; Zsom, A

    2010-01-01

    Context. Observations at sub-millimeter and mm wavelengths will in the near future be able to resolve the radial dependence of the mm spectral slope in circumstellar disks with a resolution of around a few AU at the distance of the closest star-forming regions. Aims. We aim to constrain physical models of grain growth and fragmentation by a large sample of (sub-)mm observations of disks around pre-main sequence stars in the Taurus-Auriga and Ophiuchus star-forming regions. Methods. State-of-the-art coagulation/fragmentation and disk-structure codes are coupled to produce steady-state grain size distributions and to predict the spectral slopes at (sub-)mm wavelengths. Results. This work presents the first calculations predicting the mm spectral slope based on a physical model of grain growth. Our models can quite naturally reproduce the observed mm-slopes, but a simultaneous match to the observed range of flux levels can only be reached by a reduction of the dust mass by a factor of a few up to about 30 while ...

  14. Mitigating Abnormal Grain Growth for Friction Stir Welded Al-Li 2195 Spun Formed Domes

    Science.gov (United States)

    Chen, Po-Shou; Russell, Carolyn

    2012-01-01

    Formability and abnormal grain growth (AGG) are the two major issues that have been encountered for Al alloy spun formed dome development using friction stir welded blanks. Material properties that have significant influence on the formability include forming range and strain hardening exponent. In this study, tensile tests were performed for two 2195 friction stir weld parameter sets at 400 F to study the effects of post weld anneal on the forming range and strain hardening exponent. It was found that the formability can be enhanced by applying a newly developed post weld anneal to heat treat the friction stir welded panels. This new post weld anneal leads to a higher forming range and much improved strain hardening exponent. AGG in the weld nugget is known to cause a significant reduction of ductility and fracture toughness. This study also investigated how AGG may be influenced by the heating rate to the solution heat treatment temperature. After post-weld annealing, friction stir welds were strained to 15% and 39% by compression at 400 F before they were subjected to SHT at 950 F for 1 hour. Salt bath SHT is very effective in reducing the grain size as it helps arrest the onset of AGG and promote normal recrystallization and grain growth. However, heat treating a 18 ft dome using a salt bath is not practical. Efforts are continuing at Marshall Space Flight Center to identify the welding parameters and heat treating parameters that can help mitigate the AGG in the friction stir welds.

  15. Spectroscopic infrared extinction mapping as a probe of grain growth in IRDCs

    Science.gov (United States)

    Lim, Wanggi; Carey, Sean J.

    2014-07-01

    We present photometric and spectroscopic tests of MIR to FIR extinction laws toward IRDC G028.36+00.07, a potential site of massive star formation. Lim & Tan (2014, hereafter LT14) developed methods of FIR extinction mapping of this source using Spitzer-MIPS 24 micron and Herschel-PACS 70 micron images, and extending the MIR 8 micron mapping methods of (Butler & Tan 2012, hereafter BT12), finding evidence for grain growth in the highest mass surface density regions. Here we present initial results of spectroscopic infrared extinction (SIREX) mapping using Spitzer-IRS (14 to 38 micron) data of the same IRDC. These methods allow us to measure the SED of the diffuse Galactic ISM, which we compare to theoretical models of Draine & Li (2007), as well as to search for opacity law variations with mass surface density within the IRDC. By comparison with theoretical dust models, e.g., Ossenkopf & Henning (1994) and Ormel et al. (2011), we are able to search for compositional signatures of the grain ices, such as water and methanol. We find evidence for generally flatter MIR to FIR extinction laws as mass surface density increases, strengthening the evidence for grain and ice mantle growth in higher density regions.

  16. In situ and real-time analysis of the growth and interaction of equiaxed grains by synchrotron X- ray radiography

    Science.gov (United States)

    Bogno, A.; Nguyen-Thi, H.; Billia, B.; Reinhart, G.; Mangelinck-Noël, N.; Bergeon, N.; Schenk, T.; Baruchel, J.

    2012-01-01

    The phenomena involved during equiaxed growth are dynamic, so that in situ and real-time investigation by X-ray imaging is compulsory to fully analyse the microstructure formation. The experiments on Al - 10 wt% Cu alloy of this paper are carried out at the European Synchrotron Radiation Facility (ESRF) in Grenoble (France). Equiaxed growth was achieved in nearly isothermal conditions and continuously monitored from the very early stages of solidification to an asymptotic state. First, measurements of dendrite arms velocity for a same grain showed slight differences in the early stages of the growth. This effect is attributed to a gravity-related "self - poisoning" of the grain. Then, the propagation of primary dendrite arms was analysed and two successive growth regimes were observed. First, due to the relative distance with neighbour grains, each grain could be considered as isolated (i.e. growing freely) and tip growth rate gradually increased. In a subsequent phase, tip growth rate slowly decreased towards zero, due to the proximity of neighbouring grains. Using an image analysis technique, we were able to measure the solute profiles in the liquid phase between interacting arms. These measurements confirmed that solutal impingement is responsible for stopping the grain growth.

  17. Studies on effect of oxygen flow rate in textured grain growth of ZnO thin films

    Science.gov (United States)

    Thomas, Deepu; Vattappalam, Sunil C.; Mathew, Sunny; Augustine, Simon

    2015-02-01

    ZnO thin films were deposited on glass substrate by Successive Ionic Layer Adsorption Reaction (SILAR) method. Effect of oxygen flow rate in textured grain growth, resistance and band gap of the thin films have been done. Textured grain growth of the samples were measured by comparing the peak intensities from XRD. Textured grain growth was found to be maximum when the oxygen flow rate is 2.5 litre/minute. It is found that as the oxygen flow rate increases above this limit, textured grain growth decreases and resistance the samples increases. The optical band gap of ZnO film was found to be increased with the increase of oxygen flow rate.

  18. Large-grained copper indium diselenide crystal growth by computer-controlled high-pressure liquid-encapsulated directional solidification

    Science.gov (United States)

    Schwerdtfeger, C. R.; Ciszek, T. F.

    1992-12-01

    Large-grained copper indium diselenide crystal growth by computer-controlled high-pressure liquid-encapsulated directional solidification is presented. A supply of good quality angle crystals is essential to characterization of the fundamental material properties. [AIP

  19. Grain Size and Photocatalytic Activity of Nanometer TiO2 Thin Films Prepared by the Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Transparent anatase TiO2 nanometer thin films with photocatalytic activity were prepared via the sol-gel method on soda-lime glass. The thickness, crystalline phase, grain size, surface hydroxyl amount and so on were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer (UV-VIS). The photocatalytic activity of TiO2 thin films was evaluated for the photocatalytic decolorization of aqueous methyl orange. The effects of film thickness on the crystalline phase, grain size, transmittance and photocatalytic activity of nanometer TiO2 thin films were discussed.

  20. Effect of feeding fermented liquid feed and fermented grain on gastrointestinal ecology and growth performance in piglets.

    Science.gov (United States)

    Canibe, N; Højberg, O; Badsberg, J H; Jensen, B B

    2007-11-01

    To investigate the microbial and nutritional characteristics of dry feed, liquid feed containing fermented liquid cereal grains, and fermented liquid feed, and their effect on gastrointestinal ecology and growth performance, 120 piglets from 40 litters were used and housed in pens with 5 animals in each. The 3 dietary treatments (all nonheated and nonpelleted diets) were: a dry meal diet (DRY); a fermented, liquid cereal grain feed (FLG); and a fermented liquid feed (FLF). The FLG diet was prepared by storing the dietary cereals (barley and wheat) and water (1:2.5, wt/wt) in a closed tank at 20 degrees C and adding the remaining dietary ingredients immediately before feeding. The FLF diet was prepared by storing compound feed and water (1:2.5, wt/wt) in a closed tank at 20 degrees C. Three times daily, 50% of the fermented cereals or compound feed and water stored in the tanks was removed and replaced with an equal amount of fresh cereals or feed and water. On d 14, 1 piglet from each pen was killed and samples from the gastrointestinal tract were obtained. The pH of the fermented cereals was 3.85 (SD = 0.10), that of the FLG diet was 5.00 (SD = 0.18), and the pH of the FLF diet was 4.45 (SD = 0.11). The dietary concentration of lysine (g/16 g of N) pointed to a decreased concentration in the FLF (5.46, SD = 0.08) compared with the DRY (6.01) and FLG (6.21, SD = 0.27) diets, and the concentration of cadaverine was greater in the FLF diet (890 mg/kg, SD = 151.3) than in the DRY (32 mg/kg) or FLG (153 mg/kg, SD = 18.7) diets. Fermenting only the cereal component of the diet (FLG) promoted the growth of yeasts to a greater extent than fermenting the whole diet (FLF). Terminal RFLP profiles of diets and digesta from the stomach and midcolon showed differences among dietary groups. The number of yeasts able to grow at 37 degrees C in the stomach and caudal small intestine was greatest in the FLG group compared with the other 2 dietary groups (P Feeding liquid feed

  1. Predicting Grain Growth in Nanocrystalline Materials: A Thermodynamic and Kinetic-Based Model Informed by High Temperature X-ray Diffraction Experiments

    Science.gov (United States)

    2014-10-01

    Predicting grain growth in nanocrystalline materials requires modeling approaches that incorporate grain boundary thermodynamics and kinetics. In...growth in nanocrystalline materials and this extended model can be applied to understanding how grain size evolves with temperature in other nanocrystalline systems....this work, a thermokinetic model for grain growth was applied to experimental X-ray diffraction measurements from nanocrystalline Fe Zr in an effort 1

  2. Pollen Grain Germination and Pollen Tube Growth in Pistil of Rice

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The germination of pollen grain in vitro and the growth of pollen tube in the pistil of rice were observed with a microscope.The stigma was removed at different time points after pollination to study its effect on seed setting rate.The rice pollen grain started to germinate at 2 min after pollination and the pollen tube penetrated stigma into style in 5-10 min,30 min later the end of pollen tube reached the bottom of ovary,and only some pollen tubes arrived at embryo sac at 40 min after pollination.Meanwhile,a small amount of catlose began to deposit in the pollen tubes,a great deal of callose was observed at 50 min after pollination,whereas the pollen grain began to shrink.The growing rates of pollen tube in the rice stigma,style and ovary were 1500,5000,and 5400 pm/h,respectively.The seed setting rate was quite low when the stigma was removed at about 10-15 min after pollination,gradually increased when it removed at 20 min to 50 min after pollination,and over 60%when it removed at 50 min after pollination and finally tended to be stable.

  3. The Effect of Precipitate Evolution on Austenite Grain Growth in RAFM Steel.

    Science.gov (United States)

    Yan, Biyu; Liu, Yongchang; Wang, Zejun; Liu, Chenxi; Si, Yonghong; Li, Huijun; Yu, Jianxing

    2017-09-01

    To study the effects of various types of precipitates and precipitate evolution behavior on austenite (size and phase fraction) in reduced activation ferritic/martensitic (RAFM) steel, RAFM steel was heated to various austenitizing temperatures. The microstructures of specimens were observed using optical microscopy (OM) and transmission electron microscopy (TEM). The results indicate that the M23C₆ and MX precipitates gradually coarsen and dissolve into the matrix as the austenitizing temperatures increase. The M23C₆ precipitates dissolve completely at 1100 °C, while the MX precipitates dissolve completely at 1200 °C. The evolution of two types of precipitate has a significant effect on the size of austenite. Based on the Zener pinning model, the effect of precipitate evolution on austenite grain size is quantified. It was found that the coarsening and dissolution of M23C₆ and MX precipitates leads to a decrease in pinning pressure on grain boundaries, facilitating the rapid growth of austenite grains. The austenite phase fraction is also affected by the coarsening and dissolution of precipitates.

  4. A multiscale coupled finite-element and phase-field framework to modeling stressed grain growth in polycrystalline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jamshidian, M., E-mail: jamshidian@cc.iut.ac.ir [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); Thamburaja, P., E-mail: prakash.thamburaja@gmail.com [Department of Mechanical & Materials Engineering, Universiti Kebangsaan Malaysia (UKM), Bangi 43600 (Malaysia); Rabczuk, T., E-mail: timon.rabczuk@tdt.edu.vn [Division of Computational Mechanics, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City (Viet Nam)

    2016-12-15

    A previously-developed finite-deformation- and crystal-elasticity-based constitutive theory for stressed grain growth in cubic polycrystalline bodies has been augmented to include a description of excess surface energy and grain-growth stagnation mechanisms through the use of surface effect state variables in a thermodynamically-consistent manner. The constitutive theory was also implemented into a multiscale coupled finite-element and phase-field computational framework. With the material parameters in the constitutive theory suitably calibrated, our three-dimensional numerical simulations show that the constitutive model is able to accurately predict the experimentally-determined evolution of crystallographic texture and grain size statistics in polycrystalline copper thin films deposited on polyimide substrate and annealed at high-homologous temperatures. In particular, our numerical analyses show that the broad texture transition observed in the annealing experiments of polycrystalline thin films is caused by grain growth stagnation mechanisms. - Graphical abstract: - Highlights: • Developing a theory for stressed grain growth in polycrystalline thin films. • Implementation into a multiscale coupled finite-element and phase-field framework. • Quantitative reproduction of the experimental grain growth data by simulations. • Revealing the cause of texture transition to be due to the stagnation mechanisms.

  5. CONSTRAINTS ON THE RADIAL VARIATION OF GRAIN GROWTH IN THE AS 209 CIRCUMSTELLAR DISK

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Laura M.; Carpenter, John M.; Isella, Andrea; Ricci, Luca; Sargent, Anneila I. [Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Chandler, Claire J. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Andrews, Sean M.; Harris, Robert J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Calvet, Nuria [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Corder, Stuartt A. [Joint ALMA Observatory, Av. Alonso de Cordova 3107, Vitacura, Santiago (Chile); Deller, Adam T. [The Netherlands Institute for Radio Astronomy (ASTRON), 7990-AA Dwingeloo (Netherlands); Dullemond, Cornelis P.; Linz, Hendrik [Center for Astronomy, Heidelberg University, Albert Ueberle Str. 2, D-69120 Heidelberg (Germany); Greaves, Jane S. [School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Henning, Thomas [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Kwon, Woojin [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States); Lazio, Joseph [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91106 (United States); Mundy, Lee G.; Storm, Shaye [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Testi, Leonardo [European Southern Observatory, Karl Schwarzschild Str. 2, D-85748 Garching (Germany); and others

    2012-11-20

    We present dust continuum observations of the protoplanetary disk surrounding the pre-main-sequence star AS 209, spanning more than an order of magnitude in wavelength from 0.88 to 9.8 mm. The disk was observed with subarcsecond angular resolution (0.''2-0.''5) to investigate radial variations in its dust properties. At longer wavelengths, the disk emission structure is notably more compact, providing model-independent evidence for changes in the grain properties across the disk. We find that physical models which reproduce the disk emission require a radial dependence of the dust opacity {kappa}{sub {nu}}. Assuming that the observed wavelength-dependent structure can be attributed to radial variations in the dust opacity spectral index ({beta}), we find that {beta}(R) increases from {beta} < 0.5 at {approx}20 AU to {beta} > 1.5 for R {approx}> 80 AU, inconsistent with a constant value of {beta} across the disk (at the 10{sigma} level). Furthermore, if radial variations of {kappa}{sub {nu}} are caused by particle growth, we find that the maximum size of the particle-size distribution (a{sub max}) increases from submillimeter-sized grains in the outer disk (R {approx}> 70 AU) to millimeter- and centimeter-sized grains in the inner disk regions (R {approx}< 70 AU). We compare our observational constraint on a{sub max}(R) with predictions from physical models of dust evolution in protoplanetary disks. For the dust composition and particle-size distribution investigated here, our observational constraints on a{sub max}(R) are consistent with models where the maximum grain size is limited by radial drift.

  6. Preparation of high-performance ultrafine-grained AISI 304L stainless steel under high temperature and pressure

    Directory of Open Access Journals (Sweden)

    Peng Wang

    2016-08-01

    Full Text Available Bulk ultra-fine grained (UFG AISI 304L stainless steel with excellent mechanical properties was prepared by a high-temperature and high-pressure (HTHP method using nanocrystalline AISI 304L stainless steel powders obtained from ball milling. Samples were sintered in high-pressure conditions using the highest martensite content of AISI 304L stainless steel powders milled for 25 h. Analyses of phase composition and grain size were accomplished by X-ray diffraction and Rietveld refinement. By comparing the reverse martensite transformation under vacuum and HTHP treat, we consider that pressure can effectively promote the change in the process of transformation. Compared with the solid-solution-treated 304L, the hardness and yield strength of the samples sintered under HTHP are considerably higher. This method of preparation of UFG bulk stainless steel may be widely popularised and used to obtain UFG metallic materials with good comprehensive performance.

  7. SPECTROSCOPIC INFRARED EXTINCTION MAPPING AS A PROBE OF GRAIN GROWTH IN IRDCs

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Wanggi [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Carey, Sean J. [Infrared Processing Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Tan, Jonathan C. [Departments of Astronomy and Physics, University of Florida, Gainesville, FL 32611 (United States)

    2015-11-20

    We present spectroscopic tests of MIR to FIR extinction laws in IRDC G028.36+00.07, a potential site of massive star and star cluster formation. Lim and Tan developed methods of FIR extinction mapping of this source using Spitzer-MIPS 24 μm and Herschel-PACS 70 μm images, and by comparing to MIR Spitzer-IRAC 3–8 μm extinction maps, found tentative evidence for grain growth in the highest mass surface density regions. Here we present results of spectroscopic infrared extinction mapping using Spitzer-IRS (14–38 μm) data of the same Infrared dark cloud (IRDC). These methods allow us to first measure the SED of the diffuse Galactic interstellar medium that is in the foreground of the IRDC. We then carry out our primary investigation of measuring the MIR to FIR opacity law and searching for potential variations as a function of mass surface density within the IRDC. We find relatively flat, featureless MIR–FIR opacity laws that lack the ∼12 and ∼35 μm features associated with the thick water ice mantle models of Ossenkopf and Henning. Their thin ice mantle models and the coagulating aggregate dust models of Ormel et al. are a generally better match to the observed opacity laws. We also find evidence for generally flatter MIR to FIR extinction laws as mass surface density increases, strengthening the evidence for grain and ice mantle growth in higher density regions.

  8. Large Polycrystalline Silicon Grains Prepared by Excimer Laser Crystallization of Sputtered Amorphous Silicon Film with Process Temperature at 100 °C

    Science.gov (United States)

    He, Ming; Ishihara, Ryoichi; Neihof, Ellen J. J.; van Andel, Yvonne; Schellevis, Hugo; Metselaar, Wim; Beenakker, Kees

    2007-03-01

    Large polycrystalline silicon (poly-Si) grains with a diameter of 1.8 μm are successfully prepared by excimer laser crystallization (ELC) of a sputtered amorphous silicon (α-Si) film at a maximum process temperature of 100 °C. By pulsed DC magnetron sputtering, α-Si is deposited on a non-structured oxidized wafer. It is found that the α-Si film deposited with a bias is easily ablated during ELC, even at an energy density below the super lateral growth (SLG) region. However, the α-Si film deposited without a bias can endure an energy density well beyond the SLG region without ablation. This zero-bias sputtered α-Si film with a high compressive stress has a low Ar content and a high density, which is beneficial for the suppression of ablation. Large grains with a petal-like shape can be obtained in a wide energy density window, which can be a result from some fine crystallites in the α-Si matrix. These large grains with a low process temperature are promising for the direct formation of system circuits as well as a high-quality display on a plastic foil.

  9. Growth Hormone Research Society perspective on the development of long-acting growth hormone preparations

    Science.gov (United States)

    The Growth Hormone (GH) Research Society (GRS) convened a workshop to address important issues regarding trial design, efficacy, and safety of long-acting growth hormone preparations (LAGH). A closed meeting of 55 international scientists with expertise in GH, including pediatric and adult endocrino...

  10. Preparation of pyrite-coated sand grains for research on roll-type uranium deposits

    Science.gov (United States)

    Gent, Carol A.

    1977-01-01

    Ordinary quartz sand grains can be coated with pyrite for use in laboratory experiments on the genetic geochemistry of roll-type uranium deposits. The sand is first added to a ferric chloride solution. The slow addition of sodium hydroxide to the mixture gives the sand grains an iron oxide coating. This coating is then converted to pyrite by reaction with hydrogen sulfide, thus yielding a product suitable for experimental use.

  11. Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling

    Science.gov (United States)

    Li, Li; Ungár, Tamás; Toth, Laszlo S.; Skrotzki, Werner; Wang, Yan Dong; Ren, Yang; Choo, Hahn; Fogarassy, Zsolt; Zhou, X. T.; Liaw, Peter K.

    2016-12-01

    The evolution of texture, grain size, grain shape, dislocation, and twin density has been determined by synchrotron X-ray diffraction and line profile analysis in a nanocrystalline Ni-Fe alloy after cold rolling along different directions related to the initial fiber and the long axis of grains. The texture evolution has been simulated by the Taylor-type relaxed-constraints viscoplastic polycrystal model. The simulations were based on the activity of partial dislocations in correlation with the experimental results of dislocation density determination. The concept of stress-induced shear coupling is supported and strengthened by both the texture simulations and the experimentally determined evolution of the microstructure parameters. Grain growth and texture evolution are shown to proceed by the shear coupling mechanism supported by dislocation activity as long as the grain size is not smaller than about 20 nm.

  12. EBSD coupled to SEM in situ annealing for assessing recrystallization and grain growth mechanisms in pure tantalum.

    Science.gov (United States)

    Kerisit, C; Logé, R E; Jacomet, S; Llorca, V; Bozzolo, N

    2013-06-01

    An in situ annealing stage has been developed in-house and integrated in the chamber of a Scanning Electron Microscope equipped with an Electron BackScattered Diffraction system. Based on the Joule effect, this device can reach the temperature of 1200°C at heating rates up to 100°C/s, avoiding microstructural evolutions during heating. A high-purity tantalum deformed sample has been annealed at variable temperature in the range 750°C-1030°C, and classical mechanisms of microstructural evolutions such as recrystallization and grain coarsening phenomena have been observed. Quantitative measurements of grain growth rates provide an estimate of the mean grain boundary mobility, which is consistent with the value estimated from physical parameters reported for that material. In situ annealing therefore appears to be suited for complementing bulk measurements at relatively high temperatures, in the context of recrystallization and grain growth in such a single-phase material.

  13. Investigation of mechanical properties based on grain growth and microstructure evolution of alumina ceramics during two step sintering process

    Science.gov (United States)

    Khan, U. A.; Hussain, A.; Shah, M.; Shuaib, M.; Qayyum, F.

    2016-08-01

    Alumina ceramics having small grain size and high density yield good mechanical properties, which are required in most mechanical applications. Two Step Sintering (TSS) is used to develop dense alumina ceramics. In this research work the effect of sintering temperatures on microstructure and density of the alumina specimens developed by using TSS has been investigated. It has been observed that TSS is more efficient in controlling grain growth and increasing the density as compared to One Step Sintering (OSS) of alumina. Scanning electron micrographs of sintered alumina specimens have been compared. It has been observed that TSS proves to be a better technique for increasing density and controlling grain growth of alumina ceramics than OSS. More relative density, hardness, fracture toughness and small grain size was achieved by using TSS over OSS technique.

  14. A molecular dynamics evaluation of the effect of dopant addition on grain boundary diffusion in tin: Implication for whisker growth

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, S., E-mail: soumik.banerjee@wsu.edu [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920 (United States); Dutta, I. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920 (United States); Majumdar, B.S. [Materials and Metallurgical Engineering Department, New Mexico Tech, Socorro, NM 87801 (United States)

    2016-06-01

    Addition of lead dopant has been known to be an effective way of mitigating whisker growth in tin. However, the toxic nature of lead has necessitated a search for alternative dopant species. Recent investigations have indicated that indium can be an effective agent in reducing whisker growth. In an effort to investigate if reduction in diffusivity of tin atoms near grain boundaries in presence of dopant atoms is the underlying mechanism that causes reduced whisker growth, we employed molecular dynamics simulations to model tin grain boundaries with lead and indium dopants. We simulated pure tin grain boundary as well as grain boundaries with 4% dopants by mole fraction. Our results indicate that the dopant atoms segregate near the grain boundary and forms clusters, which in turn leads to reduced diffusivity of tin atoms by up to a factor of three. Since such reduction in diffusivity alone cannot reduce whisker growth by several orders of magnitude, we conclude that other mechanisms might play a more dominant role in mitigating tin whisker growth.

  15. Characteristics of grain growth of microarc oxidation coatings on pure titanium

    Institute of Scientific and Technical Information of China (English)

    Wang Jian-Bo; Wu Han-Hua; Li Quan-Jun; Li Zhe-Kui; Gu Guang-Rui; Lü Xian-Yi; Zheng Wei-Tao; Jin Zeng-Sun

    2005-01-01

    Grainy titania coatings are prepared by microarc oxidation on pure titanium (TA2) substrates in a Na2SiO3-NaF electrolytic solution. The coating thickness is measured by an optical microscope with a CCD camera. Scanning electron microscope (SEM) and x-ray diffraction (XRD) are employed to characterize the microstructure and phase composition of coatings. The results show that the coating thickness increases linearly as the treatment time increases.The coatings are mainly composed of anatase and rutile (TiO2). With the increase of treatment time, the predominant phase composition varies from anatase to rutile, which indicates that phase transformation of anatase into rutile occurs in the oxidizing process. Meanwhile, the size of grains existing on the coating surface increases and thus the surface becomes much coarser.

  16. Investigation of the instability and low water kefir grain growth during an industrial water kefir fermentation process.

    Science.gov (United States)

    Laureys, David; Van Jean, Amandine; Dumont, Jean; De Vuyst, Luc

    2017-04-01

    A poorly performing industrial water kefir production process consisting of a first fermentation process, a rest period at low temperature, and a second fermentation process was characterized to elucidate the causes of its low water kefir grain growth and instability. The frozen-stored water kefir grain inoculum was thawed and reactivated during three consecutive prefermentations before the water kefir production process was started. Freezing and thawing damaged the water kefir grains irreversibly, as their structure did not restore during the prefermentations nor the production process. The viable counts of the lactic acid bacteria and yeasts on the water kefir grains and in the liquors were as expected, whereas those of the acetic acid bacteria were high, due to the aerobic fermentation conditions. Nevertheless, the fermentations progressed slowly, which was caused by excessive substrate concentrations resulting in a high osmotic stress. Lactobacillus nagelii, Lactobacillus paracasei, Lactobacillus hilgardii, Leuconostoc mesenteroides, Bifidobacterium aquikefiri, Gluconobacter roseus/oxydans, Gluconobacter cerinus, Saccharomyces cerevisiae, and Zygotorulaspora florentina were the most prevalent microorganisms. Lb. hilgardii, the microorganism thought to be responsible for water kefir grain growth, was not found culture-dependently, which could explain the low water kefir grain growth of this industrial process.

  17. Nanoscale Investigation of Grain Growth in RF-Sputtered Indium Tin Oxide Thin Films by Scanning Probe Microscopy

    Science.gov (United States)

    Lamsal, B. S.; Dubey, M.; Swaminathan, V.; Huh, Y.; Galipeau, D.; Qiao, Q.; Fan, Q. H.

    2014-11-01

    This work studied the electronic characteristics of the grains and grain boundaries of indium tin oxide (ITO) thin films using electrostatic and Kelvin probe force microscopy. Two types of ITO films were compared, deposited using radiofrequency magnetron sputtering in pure argon or 99% argon + 1% oxygen, respectively. The average grain size and surface roughness increased with substrate temperature for the films deposited in pure argon. With the addition of 1% oxygen, the increase in the grain size was inhibited above 150°C, which was suggested to be due to passivation of the grains by the excess oxygen. Electrostatic force microscopy and Kelvin probe force microscopy (KPFM) images confirmed that the grain growth was defect mediated and occurred at defective interfaces at high temperatures. Films deposited at room temperature with 1% oxygen showed crystalline nature, while films deposited with pure argon at room temperature were amorphous as observed from KPFM images. The potential drop across the grain and grain boundary was determined by taking surface potential line profiles to evaluate the electronic properties.

  18. [Impacts of drought stress on the growth and development and grain yield of spring maize in Northeast China].

    Science.gov (United States)

    Ji, Rui-Peng; Che, Yu-Sheng; Zhu, Yong-Ning; Liang, Tao; Feng, Rui; Yu, Wen-Ying; Zhang, Yu-Shu

    2012-11-01

    Taking spring maize variety Danyu-39 as test object, an experiment was conducted in a large-scale agricultural water controlling experimental field to study the impacts of drought stress at three key growth stages, i. e. , 3-leaf-jointing, jointing-silking, and silking-milk ripe, on the growth and development and grain yield of spring maize in Northeast China. Two treatments were installed, including moderate drought stress (MS) and re-watering to suitable water (CK). Compared with CK, the MS at 3-leaf-jointing stage postponed the whole growth period of Danyu-39 by 13 d, and the plant height and leaf area at jointing stage were decreased by 29.8% and 41.2%, respectively. After re-watering, the plant height and grain yield recovered obviously, and the differences in ear characteristics and final yield were insignificant. The MS at jointing-silking stage shortened the whole growth period by 7 d, the plant height and leaf area at silking stage were decreased by 18.6% and 14.1%, respectively, the ear length, grain number per ear, ear dry mass, and grain mass per ear decreased by 6.9%, 19.1%, 28.1%, and 29.4%, respectively, and the blank stem rate increased by 13.3%. When the maize suffered from moderate drought stress at silking-milk ripe stage, the whole growth period was shortened by 15 d, the plant height and leaf area at milk ripe stage were decreased by 2.3% and 37.3%, respectively, the ear length, grain number per ear, ear dry mass, and grain mass per ear decreased by 9.2%, 24.1%, 30.8%, and 27.9%, respectively, and the blank stem rate increased by 24.5%. After re-watering at the latter two stages, the recovery of plant height was little, and the grain yield decreased significantly.

  19. Preparation of anhydrous lanthanum bromide for scintillation crystal growth

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tong; LI Hongwei; ZHAO Chunlei; YU Jinqiu; HU Yunsheng; CUI Lei; HE Huaqiang

    2012-01-01

    This paper reported an efficient and economical method for preparation of anhydrous LaBr3 for scintillation crystal growth.High purity anhydrous LaBr3 powders in large quantities were successfully obtained by stepped dehydration of LaBr3·7H2O using NH4Br as additive.Experiments revealed that adding proper amount of NH4Br could effectively restrain the hydrolysis of LaBr3 during dehydration and thus decreased the yield of deleterious impurity of LaOBr.Optimum preparation conditions,including the amount of NH4Br in use,the dehydration temperature and atmosphere,were investigated by DTA/TG and water/oxygen analysis.The Raman characterization of the as-prepared anhydrous LaBr3 was also presented.

  20. Grain Diversity Effects on Banker Plant Growth and Parasitism by Aphidius colemani

    Directory of Open Access Journals (Sweden)

    Travis McClure

    2015-09-01

    Full Text Available Green peach aphid (Myzus persicae Sulzer (Hemiptera: Aphididae is a serious greenhouse pest with a short generation time, parthenogenetic reproduction and a broad host range. Banker plant systems are becoming a more common form of biological control for this pest. This system consists of grain “banker plants” infested with R. padi, an alternative hosts for the parasitoid Aphidius colemani. Thus A. colemani can reproduce on the banker plant when M. persicae populations are low. This system can increase pest suppression; however, like other biological control tools, efficacy is inconsistent. One reason is because several different grain species have been used. Our studies determined if there were benefits to planting interspecific mixture banker plants, similar to when open agricultural systems use mixed cropping. Our study found that although banker plants grow larger when planted as mixtures this added plant growth does not increase in the number of aphids, or mummies an individual banker plant can sustain. Rye banker plants grew larger, and sustained more mummies than the other species we tested, but barley banker plants resulted in a similar number of aphids in a more condensed area. Ultimately, we did not see any differences in pest suppression between monoculture banker plants, mixture banker plants, or our augmentative release treatment. However, using banker plants resulted in more female parasitoids than the augmentative release, a benefit to using banker plant systems.

  1. Effects of Nitrogen Application in Different Wheat Growth Stages on the Floret Development and Grain Yield of Winter Wheat

    Institute of Scientific and Technical Information of China (English)

    ZHU Yun-ji; WANG Chen-yang; GUO Tian-cai; CUI Jin-mei; XIA Guo-jun; LIU Wan-dai; WANG Yong-hua

    2002-01-01

    The study was carried out on the effect of nitrogen application in different wheat growth stage on the floret development, the photosynthetic rate, the yield and its components of winter wheat. The result indicated that nitrogen application in the pistil-stamen primordium formation stage and the tetrad formation stage of wheat growth prolonged the duration of floret development, promoted the balance growth of floret and reduced the floret decadence number, thus increased the grain number per spike. Nitrogen application in the middle and in the late stages of wheat development increased the photosynthetic ability of the plant leaves in the later stage, and also lengthened the peak of grain filling stage, thus enhanced the grain weight and yield of wheat significantly.

  2. Effects of oxide coating on the growth of single grain YBCO bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.D.; Jun, B.-H. [Neutron Science Division, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353 (Korea, Republic of); Park, B.J.; Jung, S.Y. [Superconductivity and Applications Group, Korea Electric Power Research Institute (KEPRI), Daejeon 305-380 (Korea, Republic of); Seong, B.S. [Neutron Science Division, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353 (Korea, Republic of); Kim, C.-J., E-mail: cjkim2@kaeri.re.k [Neutron Science Division, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353 (Korea, Republic of)

    2009-10-15

    Surface oxide coating and bottom inserting of oxide plates have been conducted to top seeded melt growth (TSMG) processed YBa{sub 2}Cu{sub 3}O{sub 7-y} (Y123) bulk superconductors with an aim of controlling the Y123 nucleation and growth. The coating medium for surfaces was Yb{sub 2}O{sub 3} solution and the bottom inserts were Yb{sub 2}O{sub 3}/Y{sub 2}O{sub 3} powder compact. Many vertical cracks were found to develop at the compact/insert interfaces when an Yb{sub 2}O{sub 3} insert was used, but the crack evolution was greatly reduced when a (Yb{sub 2}O{sub 3} + Y{sub 2}O{sub 3}) insert was used. The formation of the vertical cracks is ascribed to the difference in thermal expansion between the YBCO compact and bottom insert. Presence of vertical cracks was found to be crucial to the trapped magnetic field and levitation forces of single grain YBCO bulk superconductors. The Y123 nucleation and growth in TSMG-processed YBCO bulk superconductors were successfully controlled by conducting surface coating and bottom plating using a (Yb{sub 2}O{sub 3} + Y{sub 2}O{sub 3}) insert and as a result, the levitation properties were much enhanced.

  3. Preparation, cryopreservation, and growth of cells prepared from the green turtle (Chelonia mydas)

    Science.gov (United States)

    Moore, M.K.; Work, T.M.; Balazs, G.H.; Docherty, D.E.

    1997-01-01

    Techniques are described for preparing, preserving, and growing cell cultures from 30 to 40-day old green turtle embryos (2.0-3.0 cm length) including cells derived from skeletal muscle, liver, heart, kidney, eye, lung, and brain. Acceptable growth of all cells occurred in all standard cell culture media tested, with optimum growth temperature near 30??C. These cell cultures will be used in the study of sea turtle viral diseases including fibropapillomatosis, which is currently epidemic in some green turtle populations.

  4. Growth Hormone Research Society perspective on the development of long-acting growth hormone preparations

    DEFF Research Database (Denmark)

    Christiansen, Jens Sandahl; Backeljauw, Philippe F; Bidlingmaier, Martin

    2016-01-01

    OBJECTIVE: The Growth Hormone (GH) Research Society convened a workshop to address important issues regarding trial design, efficacy, and safety of long-acting GH preparations (LAGH). PARTICIPANTS: A closed meeting of 55 international scientists with expertise in growth hormone, including pediatric...... and adult endocrinologists, basic scientists, regulatory scientists, and participants from the pharmaceutical industry. EVIDENCE: Current literature was reviewed for gaps in knowledge. Expert opinion was utilized to suggest studies required to address potential safety and efficacy issues. CONSENSUS PROCESS...

  5. Effect of Mg Addition on Inhibiting Austenite Grain Growth in Heat Affected Zones of Ti-Bearing Low Carbon Steels%Effect of Mg Addition on Inhibiting Austenite Grain Growth in Heat Affected Zones of Ti-Bearing Low Carbon Steels

    Institute of Scientific and Technical Information of China (English)

    ZHU Kai; YANG Jian; WANG Rui-zhi; YANG Zhen-guo

    2011-01-01

    To study the effect of Mg addition on inhibiting weld heat affected zones (HAZ) austenite grain growth of Ti-bearing low carbon steels, two steels with and without Mg treated were prepared using a laboratory vacuum. The welding testing was simulated by Gleeble 3500 thermomechanical simulator. The performance of HAZ was investiga ted that the toughness was improved from 3.3 to 185 J by adding 0. 005%Mg (in mass percent) to the steel, and the fracture mechanism changed from cleavage fracture to toughness fracture. Through in-situ observation by a confocal scanning laser microscope, a significant result was found that the austenite grain of the steel with Mg treated was still keeping fine-grained structure after holding at 1 400℃ and lasting for 300 s. This inhibition of austenite grain growth was mainly attributed to the formation of pinning particles after the addition of Mg. The obtained results pro pose a potential method for improving HAZ toughness of structure steels.

  6. Recrystallization and grain growth behavior of rolled tungsten under VDE-like short pulse high heat flux loads

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Y. [Laboratory of Advanced Materials, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China); Greuner, H.; Böswirth, B.; Krieger, K. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, 85748 Garching (Germany); Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Xu, H.Y.; Fu, B.Q.; Li, M. [Laboratory of Advanced Materials, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, W., E-mail: liuw@mail.tsinghua.edu.cn [Laboratory of Advanced Materials, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2013-02-15

    Highlights: ► Recrystallization temperature of a rolled W was ∼2480 °C under applied HHF loads. ► Fine grains were obtained under HHF loads with appropriate short pulse length. ► With increasing pulse length, the recrystallized grains significantly grew larger. ► A linear relationship between ln d and 1/T{sub max} was found. ► Activation energy for grain growth in T evolution up to T{sub max} in 1.5 s was obtained. -- Abstract: Short pulse heat loads expected for vertical displacement events (VDEs) in ITER were applied in the high heat flux (HHF) test facility GLADIS at IPP-Garching onto samples of rolled W. Pulsed neutral beams with the central heat flux of 23 MW/m{sup 2} were applied for 0.5, 1.0 and 1.5 s, respectively. Rapid recrystallization of the adiabatically loaded 3 mm thick samples was observed when the pulse duration was up to 1.0 s. Grains grew markedly following recrystallization with increasing pulse length. The recrystallization temperature and temperature dependence of the recrystallized grain size were also investigated. The results showed that the recrystallization temperature of the W grade was around 2480 °C under the applied heat loading condition, which was nearly 1150 °C higher than the conventional recrystallization temperature, and the grains were much finer. A linear relationship between the logarithm of average grain size (ln d) and the inverse of maximum surface temperature (1/T{sub max}) was found and accordingly the activation energy for grain growth in temperature evolution up to T{sub max} in 1.5 s of the short pulse HHF load was deduced to be 4.1 eV. This provided an effective clue to predict the structure evolution under short pulse HHF loads.

  7. The Structure and Mechanical Properties of High-Strength Bulk Ultrafine-Grained Cobalt Prepared Using High-Energy Ball Milling in Combination with Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Ivo Marek

    2016-05-01

    Full Text Available In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as the compressive yield strength, the ultimate compressive strength, the maximum compressive deformation and the Vickers hardness were studied and compared with those of a coarse-grained as-cast cobalt reference sample. The bulk ultrafine-grained sample showed an ultra-high compressive yield strength that was greater than 1 GPa, which is discussed with respect to the preparation technique and a structural investigation.

  8. Effect of second phase particles topology on the onset temperature of abnormal grain growth in Fe - 3%Si steels

    Directory of Open Access Journals (Sweden)

    Stoyka, V.

    2008-01-01

    Full Text Available The relations between regimes of dynamic annealing, state of secondary particles system and the onset temperature of abnormal grain growth are investigated. Two distinguish types of Fe-3%Si grain-oriented steels, after one and two stage cold rolling, were studied. The second phase particles remain unaffected in first type of steel during the heat treatment. Vice versa, the increased density of second phases was observed after annealing in the second type of the investigated materials. It is shown that start/onset of abnormal grain growth strongly depends on both volume fraction of second phase particles and annealing temperature. Texture and magnetic properties of the investigated samples are investigated within the current study.

  9. Effect of cobalt oxide on the sintering and grain growth of Al2O3-YAG composite nanopowder

    Directory of Open Access Journals (Sweden)

    Hassanzadeh-Tabrizi S.A.

    2010-01-01

    Full Text Available In the present study, the effect of cobalt oxide on the densification of Al2O3-YAG composite nanopowder was investigated. An amorphous nanopowder was synthesized and crystallized to Al2O3-YAG after heat-treatment via a solid-state reaction. The average particle size of heat-treated powder at 800°C was about 80 nm. Cobalt oxide improved the sintering rate of Al2O3-YAG composite nanopowders and promoted grain boundary mobility. Cobalt oxide doping increased the ratio of densification/grain growth rate. The activation energy for grain growth decreased from 590 to 485 kJ/mol by adding cobalt oxide to the composite nanopowder.

  10. Growth Kinetics of Monodisperse Polystyrene Microspheres Prepared by Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Fan Li

    2013-01-01

    Full Text Available Dispersion polymerization has been widely applied to the synthesis of monodisperse micron-sized polymer colloidal spheres. Many efforts have been devoted to studying the influence of initial conditions on the size and uniformity of the resultant microspheres, aiming to synthesize micron-size monodisperse colloidal spheres. However, the inner contradiction between the size and the size distribution of colloidal spheres hinders the realization of this goal. In this work, we drew our attention from the initial conditions to the growth stage of dispersion polymerization. We tracked the size evolution of colloidal sphere during the dispersion polymerization, through which we established a kinetic model that described the relationship between the monomer concentration and the reaction time. The model may provide a guideline to prepare large polymer colloidal spheres with good monodispersity by continuous monomer feeding during the growth stage to maintain the concentration of monomer at a constant value in a dispersion polymerization process.

  11. Microbial profile of a kefir sample preparations: grains in natura and lyophilized and fermented suspension

    Directory of Open Access Journals (Sweden)

    Rafaela Strada de Oliveira Bergmann

    2010-12-01

    Full Text Available Probiotics are supplementary foods developed by microbial strains that improve animal health beyond basic nutrition. Probiotics are consumed orally, regardless of being considered as normal inhabitants of the intestines, able to survive in enzimatic and biliary secretions. Kefir is a probiotic originated from the old continent, fermented by several bacteria and yeasts, encapsulated in a polyssacharide matrix, and resembles jelly grains. Kefir is also presented as its sourish product both in sugary or milky suspensions containing vitamins, aminoacids, peptides, carbohydrates, ethanol, and volatile compounds. Kefir is known to have a diverse microbial content depending on the country and fermentative substrates, which cause distinct probiotic effects. In this sense, the purpose of this work was to isolate, identify, and quantify the microbial content of a native sugary kefir sample (fermented suspension and lyophilized natural grains. Serial dilutions were plated on Rogosa agar (AR and De Man, Rogosa and Sharpe (MRS, for Lactobacillus; Brain Heart Infusion (BHI, for total bacteria; Sabouraud-Dextrose-Agar (SDA, for yeasts and filamentous fungi; Thioglycolate Agar (TA, for Streptococcus, Acetobacteria and Leuconostoc; and Coconut Water Agar (CWA, and CWA supplemented with yeast extract (CWAY, for various genera. Genera and species for all strains were identified through biochemical reactions and specific API systems. The microbial profile of kefir was different from other sources of grains despite the presence of similar microorganisms and others which have not been reported yet. The data obtained with the CWA and CWAE media suggest that both substrates are alternative and salutary media for culture of kefir strains.

  12. Grain Nucleation and Growth in Deformed NiTi Shape Memory Alloys: An In Situ TEM Study

    Science.gov (United States)

    Burow, J.; Frenzel, J.; Somsen, C.; Prokofiev, E.; Valiev, R.; Eggeler, G.

    2017-09-01

    The present study investigates the evolution of nanocrystalline (NC) and ultrafine-grained (UFG) microstructures in plastically deformed NiTi. Two deformed NiTi alloys were subjected to in situ annealing in a transmission electron microscope (TEM) at 400 and 550 °C: an amorphous material state produced by high-pressure torsion (HPT) and a mostly martensitic partly amorphous alloy produced by wire drawing. In situ annealing experiments were performed to characterize the microstructural evolution from the initial nonequilibrium states toward energetically more favorable microstructures. In general, the formation and evolution of nanocrystalline microstructures are governed by the nucleation of new grains and their subsequent growth. Austenite nuclei which form in HPT and wire-drawn microstructures have sizes close to 10 nm. Grain coarsening occurs in a sporadic, nonuniform manner and depends on the physical and chemical features of the local environment. The mobility of grain boundaries in NiTi is governed by the local interaction of each grain with its microstructural environment. Nanograin growth in thin TEM foils seems to follow similar kinetic laws to those in bulk microstructures. The present study demonstrates the strength of in situ TEM analysis and also highlights aspects which need to be considered when interpreting the results.

  13. Effect of different growth conditions on biomass increase in kefir grains.

    Science.gov (United States)

    Guzel-Seydim, Z; Kok-Tas, T; Ertekin-Filiz, B; Seydim, A C

    2011-03-01

    Kefir is a functional dairy product and the effects of kefir consumption on health have been well documented. Kefir grains have naturally high numbers of lactic acid bacteria and yeasts and are used in manufacturing kefir. The biomass of kefir grains slowly increases after successive fermentations. The effects of adding whey protein isolate, modified whey protein (MWP, fat replacer; Carbery Inc., Cork, Ireland), or inulin to milk and different atmospheric conditions (ambient or 6% CO(2)) during fermentation on the increase in biomass of kefir grains were investigated. Reconstituted milks (10% milk powder) enriched with whey protein isolate (2%), MWP (2%), and inulin (2%) were inoculated with kefir grains and fermented in ambient and 6% CO(2) incubators at 25°C until a final pH of 4.6 was reached. Biomass increments of kefir grains were determined weekly over 30 d. Lactic acid bacteria and yeast contents of kefir grains were also determined. The highest biomass increase (392%) was found in kefir grains grown in milk supplemented with whey protein isolate under ambient atmospheric conditions. Application of CO(2) did not provide a significant supporting effect on the biomass of kefir grains. Addition of MWP significantly accelerated the formation of kefir grain biomass (223%). The use of whey protein isolate, MWP, or inulin in milk did not cause any adverse effects on the microbial flora of kefir grains. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  14. High temperature grain growth and oxidation of Fe-29Ni-17Co (Kovar{trademark}) alloy leads

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, J.J.; Greulich, F.A.; Beavis, L.C.

    1993-12-31

    One important application for the Fe-29Ni-17Co (Kovar{trademark}) alloy in wire form is in brazed feed through assemblies which are integral parts of vacuum electronic devices. Since Cu metal brazes are performed at process temperatures of about 1100{degrees}C, there is opportunity for significant grain growth to occur during the brazing operation. Additional high temperature exposure includes decarburization of the Fe-29Ni-17Co alloy wire in wet hydrogen for 30 min. at 1000{degrees}C prior to the Cu brazing operation. Two approaches have been used to characterize grain growth in two lots of Fe-29Ni-17Co alloy: (1) a once-through processing study to study the effect of one-time-only device thermal processing on the resulting grain size, and (2) an isothermal grain growth study involving various times at 800--1100{degrees}C. The results of the once-through processing study indicate that acceptable grain sizes are obtained from both cold worked and mill-annealed wire lots following Cu brazing. The isothermal grain growth study indicates that the linear intercept distance for Fe-29Ni-17Co can be described with a power law function of time, and that thermal exposure must be controlled at temperatures in excess of 900{degrees}C in order to avoid excessive grain growth. A second study has characterized the oxidation kinetics of Fe-29Ni-17Co alloy wire in air at temperatures ranging from 550--700{degrees}C. This study indicates the parabolic growth law applies for this material, and between 550 and 700{degrees}C, oxidation in this alloy occurs at an activation energy of 27.9 kcal/mole. Other oxidation studies at higher temperatures ({ge}750{degrees}C) indicate an activation energy of 52.2 kcal/mole for oxidation of Fe-29Ni-17Co alloy at temperatures greater than 790{degrees}C. Quantitative point analyses of the oxide scale formed at 600{degrees}C suggest that a significant fraction of the scale is close to the stoichiometry of the Fe{sub 2}O{sub 3}-type oxide.

  15. Dust grain growth in the interstellar medium of galaxies at redshifts 4

    CERN Document Server

    Michałowski, Michał J; Hjorth, Jens; Watson, Darach; Gall, Christa; Dunlop, James S

    2011-01-01

    To discriminate between different dust formation processes is a key issue in order to understand its properties. We analysed six submillimeter galaxies at redshifts 4grain growth in the interstellar medium is responsible for bulk of the dust mass accumulation in these galaxies.

  16. Modeling Growth and Dissolution Kinetics of Grain-Boundary Cementite in Cyclic Carburizing

    Science.gov (United States)

    Ikehata, Hideaki; Tanaka, Kouji; Takamiya, Hiroyuki; Mizuno, Hiroyuki; Shimada, Takeyuki

    2013-08-01

    In vacuum carburizing of steels, short-time carburizing is usually followed by a diffusion period to eliminate the filmlike cementite ( θ GB ) grown on the austenite ( γ) grain boundary surface. In order to obtain the θ GB amount during the process, the conventional model estimates the amount of cementite ( θ) with the equilibrium fractions for local C contents within a framework of the finite difference method (FDM), which overestimates the amount of θ GB observed after several minutes of carburizing. In our newly developed model, a parabolic law is assumed for the growth of θ GB and the rate controlling process is considered to be Si diffusion rejected from θ under the isoactivity condition. In contrast, the rate constant for the dissolution of θ GB is considered to be controlled by Cr diffusion of θ. Both rate coefficients ( α) were validated using multicomponent diffusion simulation for the moving velocity of the γ/ θ interface. A one-dimensional (1-D) FDM program calculates an increment of θ GB for all grid points by the updated diffusivities and local equilibrium using coupled CALPHAD software. Predictions of the carbon (C) profile and volume fraction of cementite represent the experimental analysis much better than the existing models, especially for both short-time carburization and the cyclic procedure of carburization and diffusion processes.

  17. Spectroscopic infrared extinction mapping as a probe of grain growth in IRDCs

    CERN Document Server

    Lim, Wanggi; Tan, Jonathan C

    2015-01-01

    We present spectroscopic tests of MIR to FIR extinction laws in IRDC G028.36+00.07, a potential site of massive star and star cluster formation. Lim & Tan (2014) developed methods of FIR extinction mapping of this source using ${\\it Spitzer}$-MIPS ${\\rm 24\\mu m}$ and ${\\it Herschel}$-PACS ${\\rm 70\\mu m}$ images, and by comparing to MIR ${\\it Spitzer}$-IRAC $3$--${\\rm 8\\mu m}$ extinction maps, found tentative evidence for grain growth in the highest mass surface density regions. Here we present results of spectroscopic infrared extinction (SIREX) mapping using ${\\it Spitzer}$-IRS (14 to ${\\rm 38\\mu m}$) data of the same IRDC. These methods allow us to first measure the SED of the diffuse Galactic ISM that is in the foreground of the IRDC. We then carry out our primary investigation of measuring the MIR to FIR opacity law and searching for potential variations as a function of mass surface density within the IRDC. We find relatively flat, featureless MIR-FIR opacity laws that lack the $\\sim{\\rm 12\\mu m}$ an...

  18. Effect of zirconium on grain growth and mechanical properties of a ball-milled nanocrystalline FeNi alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kotan, Hasan, E-mail: hkotan@ncsu.edu [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States); Darling, Kris A. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Saber, Mostafa; Koch, Carl C.; Scattergood, Ronald O. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Pure Fe, Fe{sub 92}Ni{sub 8}, and Fe{sub 91}Ni{sub 8}Zr{sub 1} powders were hardened up to 10 GPa by ball milling. Black-Right-Pointing-Pointer Annealing of Fe and Fe{sub 92}Ni{sub 8} leads to reduced hardness and extensive grain growth. Black-Right-Pointing-Pointer The addition of Zr to Fe{sub 92}Ni{sub 8} increases its stability and strength by second phases. Black-Right-Pointing-Pointer The second phases are found to promote the stability of Fe{sub 91}Ni{sub 8}Zr{sub 1} by Zener pinning. Black-Right-Pointing-Pointer The Zr-containing precipitates contribute to the overall strength of the material. - Abstract: Grain growth of ball-milled pure Fe, Fe{sub 92}Ni{sub 8}, and Fe{sub 91}Ni{sub 8}Zr{sub 1} alloys has been studied using X-ray diffractometry (XRD), focused ion beam (FIB) microscopy and transmission electron microscopy (TEM). Mechanical properties with respect to compositional changes and annealing temperatures have been investigated using microhardness and shear punch tests. We found the rate of grain growth of the Fe{sub 91}Ni{sub 8}Zr{sub 1} alloy to be much less than that of pure Fe and the Fe{sub 92}Ni{sub 8} alloy at elevated temperatures. The microstructure of the ternary Fe{sub 91}Ni{sub 8}Zr{sub 1} alloy remains nanoscale up to 700 Degree-Sign C where only a few grains grow abnormally whereas annealing of pure iron and the Fe{sub 92}Ni{sub 8} alloy leads to extensive grain growth. The grain growth of the ternary alloy at high annealing temperatures is coupled with precipitation of Fe{sub 2}Zr. A fine dispersion of precipitated second phase is found to promote the microstructural stability at high annealing temperatures and to increase the hardness and ultimate shear strength of ternary Fe{sub 91}Ni{sub 8}Zr{sub 1} alloy drastically when the grain size is above nanoscale.

  19. Two-dimensional phase-field study of competitive grain growth during directional solidification of polycrystalline binary alloy

    Science.gov (United States)

    Takaki, Tomohiro; Ohno, Munekazu; Shibuta, Yasushi; Sakane, Shinji; Shimokawabe, Takashi; Aoki, Takayuki

    2016-05-01

    Selections of growing crystals during directional solidification of a polycrystalline binary alloy were numerically investigated using two-dimensional phase-field simulations. To accelerate the simulations, parallel graphics processing unit (GPU) simulations were performed using the GPU-rich supercomputer TSUBAME2.5 at the Tokyo Institute of Technology. Twenty simulations with a combination of five sets of different seed orientation distributions and four different temperature gradients covering dendritic and cellular growth regions were performed. The unusual grain selection phenomenon, in which the unfavorably oriented grains preferentially grow instead of the favorably oriented grains, was observed frequently. The unusual selection was more remarkable in the cellular structure than in the dendritic structure.

  20. Roles of Microwave Oven in Preparing Microbiological Growth Media

    Directory of Open Access Journals (Sweden)

    Christian Prijana

    2016-03-01

    Full Text Available Background: Sterilization of a growth medium before being utilized is a very important step in a microbiology laboratory. The common method for this purpose is by using the autoclave. However, autoclaving takes more time. To overcome this limitation, we tried to use the microwave oven. The aim of this study was to evaluate the ability of microwave oven in preparing the growth media. Methods: This was a laboratory experimental study conducted at Microbiology Laboratory, Faculty of Medicine, Universitas Padjadjaran, from October to November 2014. The growth media used were: MacConkey agar, in petri dishes, inoculated with Escherichia coli; Sabouraud agar, in petri dishes, inoculated with Candida albicans; Kligler iron agar (KIA, in reaction tubes, inoculated with Escherichia coli and Salmonella Typhi; Simmons citrate agar, in reaction tubes, inoculated with Klebsiella pneumoniae; Mueller-Hinton (M-H broth, in reaction tubes, inoculated with Escherichia coli; and Motility Indole Urea (MIU semisolid agar, in reaction tubes, inoculated with Proteus sp.The media would be heated by microwave for 1, 2, and 3 minutes. Results: From the total 54 dishes/tubes of various microwave-sterilized media, contaminations were only seen at 5 dishes/tubes. Most of the media, except the one-minute-heated Mueller-Hinton broth, were sterilized more than half dishes/tubes. The identification function of all media in this study was performed well. Conclusions: The utilization of microwave oven as an alternative sterilizing apparatus for microbiological growth media is very potential, particularly for two and three minutes duration of heating.

  1. Grain Growth Orientation and Anisotropy in Cu6Sn5 Intermetallic: Nanoindentation and Electron Backscatter Diffraction Analysis

    Science.gov (United States)

    Choudhury, Soud Farhan; Ladani, Leila

    2014-04-01

    As the size of joints in micro/nano-electronics diminishes, the role of intermetallic (IMC) layers becomes more significant. It was shown that solder joint strength is controlled largely by IMC strength at higher strain rates. Additionally, there is a possibility that very small joints are completely composed of IMCs. Further miniaturization of joints may result in statistical grain size effects. Therefore, it is essential to characterize IMC materials and understand their anisotropic mechanical properties. One of the most common types of IMCs in microelectronic joints is Cu6Sn5, which is formed in a variety of bonding materials with different compositions of Sn, Cu, and Ag. This work studies through nanoindentation elastic-plastic properties of a single grain of Cu6Sn5 IMC in a Sn-3.5Ag/Cu system with reflow soldering. Elastic properties such as elastic modulus and hardness were determined from the nanoindentation load-depth curve. The reverse analysis model described by Dao et al. was used to extract plastic properties such as yield strength and strain hardening exponent from nanoindentation data. Care was taken to achieve indentation of single grains with sufficient accuracy and repeatability. Electron backscatter diffraction (EBSD) mapping was used to determine orientation of Cu6Sn5 grains and to relate the orientation with the load-depth curve results of nanoindentation and the corresponding elastic and plastic properties. The EBSD results indicated that the Cu6Sn5 crystal structure is hexagonal. Columnar growth of the Cu6Sn5 grains was observed as the grains mostly grew along the c-axis of the crystal. Indentation of different grains parallel to the basal plane showed no significant difference in mechanical properties.

  2. Status of long-acting-growth hormone preparations--2015.

    Science.gov (United States)

    Høybye, Charlotte; Cohen, Pinchas; Hoffman, Andrew R; Ross, Richard; Biller, Beverly M K; Christiansen, Jens Sandahl

    2015-10-01

    Growth hormone (GH) treatment has been an established therapy for GH deficiency (GHD) in children and adults for more than three decades. Numerous studies have shown that GH treatment improves height, body composition, bone density, cardiovascular risk factors, physical fitness and quality of life and that the treatment has few side effects. Initially GH was given as intramuscular injections three times per week, but daily subcutaneous injections were shown to be more effective and less inconvenient and the daily administration has been used since its introduction in the 1980s. However, despite ongoing improvements in injection device design, daily subcutaneous injections remain inconvenient, painful and distressing for many patients, leading to noncompliance, reduced efficacy and increased health care costs. To address these issues a variety of long-acting formulations of GH have been developed. In this review we present the current status of long-acting GH preparations and discuss the specific issues related to their development.

  3. Replacement of mineral fertilizers with anaerobically digested pig slurry in paddy fields: assessment of plant growth and grain quality.

    Science.gov (United States)

    Zhang, Jin; Wang, Minyan; Cao, Yucheng; Liang, Peng; Wu, Shengchun; Leung, Anna Oi Wah; Christie, Peter

    2017-04-01

    Rice cultivation requires large quantities of irrigation water and mineral fertilizers. This provides an opportunity for the recycling of the plant nutrients in anaerobically digested pig slurry, large amounts of which are generated in Chinese pig farms. Hence, to promote the sustainable development of livestock and poultry breeding and rice production, a micro-plot field experiment was carried out to assess whether or not slurry can replace mineral fertilizers in rice paddy production in terms of plant tillering, grain quality, and yields. The results indicate that the total N content of the slurry can serve as an alternative source of N when compared to the control (450 kg ha(-1) commercial compound fertilizer (N/P2O5/K2O = 15:15:15) as basal fertilizer, 300 kg ha(-1) urea (N% = 46), and 150 kg ha(-1) commercial compound fertilizer as top-dressed fertilizer). No negative effects on plant growth or grain yield were observed, although there may be a potential risk due to an increase in grain Cu concentration. The amylose content and gel consistency of the rice grains were enhanced significantly by the use of slurry as a basal fertilizer, but the grain protein and total amino acid contents decreased. The results suggest that anaerobically digested pig slurry can replace mineral fertilizers in rice production when applied as a basal dressing together with urea and commercial compound fertilizer as top-dressed fertilizers.

  4. Recrystallization and grain growth behavior of rolled tungsten under VDE-like short pulse high heat flux loads

    Science.gov (United States)

    Yuan, Y.; Greuner, H.; Böswirth, B.; Krieger, K.; Luo, G.-N.; Xu, H. Y.; Fu, B. Q.; Li, M.; Liu, W.

    2013-02-01

    Short pulse heat loads expected for vertical displacement events (VDEs) in ITER were applied in the high heat flux (HHF) test facility GLADIS at IPP-Garching onto samples of rolled W. Pulsed neutral beams with the central heat flux of 23 MW/m2 were applied for 0.5, 1.0 and 1.5 s, respectively. Rapid recrystallization of the adiabatically loaded 3 mm thick samples was observed when the pulse duration was up to 1.0 s. Grains grew markedly following recrystallization with increasing pulse length. The recrystallization temperature and temperature dependence of the recrystallized grain size were also investigated. The results showed that the recrystallization temperature of the W grade was around 2480 °C under the applied heat loading condition, which was nearly 1150 °C higher than the conventional recrystallization temperature, and the grains were much finer. A linear relationship between the logarithm of average grain size (ln d) and the inverse of maximum surface temperature (1/Tmax) was found and accordingly the activation energy for grain growth in temperature evolution up to Tmax in 1.5 s of the short pulse HHF load was deduced to be 4.1 eV. This provided an effective clue to predict the structure evolution under short pulse HHF loads.

  5. Piezoelectric Properties of Bismuth Layer-Structured Ferroelectric Ceramics with a Preferred Orientation Processed by the Reactive Templated Grain Growth Method

    Science.gov (United States)

    Takeuchi, Tsuguto; Tani, Toshihiko; Saito, Yasuyoshi

    1999-09-01

    Dense CaBi4Ti4O15 (CBT) and Na0.475Ca0.05Bi4.475Ti4O15 (NCBT) ceramics with a highly preferred {001} orientation were prepared by the reactive templated grain growth (RTGG) method. Plate-like Bi4Ti3O12 (BIT) particles were synthesized by a molten salt technique and used as the reactive template. The template particles were mixed with other oxide and carbonate powders and aligned by tape-casting. During the sintering, oriented CBT and NCBT were formed in situ topotaxially on the oriented BIT particles, and textured CBT and NCBT ceramics were eventually fabricated by the templated grain growth and densification. The Lotgering {001} orientation degree of the textured ceramics exceeded 90% for secondary-laminate sintered specimens. Textured CBT and NCBT ceramics poled in the perpendicular direction to the preferred axis exhibited electromechanical coupling coefficient (k33) and piezoelectric coefficients (d33 and g33) three times higher than the values for nontextured ceramics with the same composition.

  6. Synthesis mechanism of an Al-Ti-C grain refiner master alloy prepared by a new method

    Science.gov (United States)

    Zhang, B. Q.; Lu, L.; Lai, M. O.; Fang, H. S.; Ma, H. T.; Li, J. G.

    2003-08-01

    The mechanisms of in-situ synthesis of an Al-Ti-C grain-refiner master alloy, prepared by adding a powder mixture of potassium titanium fluoride and carbon into an aluminum melt, have been systematically studied. It was found that vigorous reactions occurred at the initial stage of reaction and then slowed down. After about 20 minutes, the reactions, which led the formation of blocky titanium aluminides and submicron titanium carbides in the aluminum matrix, appeared to reach completion. Potassium titanium fluoride reacted with aluminum and carbon at 724 °C and 736 °C, respectively, resulting in the formation of titanium aluminides and titanium carbides in the aluminum matrix as well as in the formation of a low-melting-point slag of binary potassium aluminofluorides. The reaction between potassium titanium fluoride and carbon is believed to be the predominant mechanism in the synthesis of TiC by this method.

  7. Plant growth promoting bacteria from cow dung based biodynamic preparations.

    Science.gov (United States)

    Radha, T K; Rao, D L N

    2014-12-01

    Indigenous formulations based on cow dung fermentation are commonly used in organic farming. Three biodynamic preparations viz., Panchagavya (PG), BD500 and 'Cow pat pit' (CPP) showed high counts of lactobacilli (10(9) ml(-1)) and yeasts (10(4) ml(-1)). Actinomycetes were present only in CPP (10(4) ml(-1)) and absent in the other two. Seven bacterial isolates from these ferments were identified by a polyphasic approach: Bacillus safensis (PG1), Bacillus cereus (PG2, PG4 PG5), Bacillus subtilis (BD2) Lysinibacillus xylanilyticus (BD3) and Bacillus licheniformis (CPP1). This is the first report of L. xylanilyticus and B. licheniformis in biodynamic preparations. Only three carbon sources-dextrose, sucrose and trehalose out of 21 tested were utilized by all the bacteria. None could utilize arabinose, dulcitol, galactose, inositol, inulin, melibiose, raffinose, rhamnose and sorbitol. All the strains produced indole acetic acid (1.8-3.7 μg ml(-1) culture filtrate) and ammonia. None could fix nitrogen; but all except B. safensis and B. licheniformis could solubilize phosphorous from insoluble tri-calcium phosphate. All the strains except L. xylaniliticus exhibited antagonism to the plant pathogen Rhizoctonia bataticola whereas none could inhibit Sclerotium rolfsi. In green house experiment in soil microcosms, bacterial inoculation significantly promoted growth of maize; plant dry weight increased by ~21 % due to inoculation with B. cereus (PG2). Results provide a basis for understanding the beneficial effects of biodynamic preparations and industrial deployment of the strains.

  8. Texturing of sodium bismuth titanate-barium titanate ceramics by templated grain growth

    Science.gov (United States)

    Yilmaz, Huseyin

    2002-01-01

    Sodium bismuth titanate modified with barium titanate, (Na1/2Bi 1/2)TiO3-BaTiO3 (NBT-BT), is a candidate lead-free piezoelectric material which has been shown to have comparatively high piezoelectric response. In this work, textured (Na1/2Bi1/2)TiO 3-BaTiO3 (5.5mol% BaTiO3) ceramics with pc (where pc denotes the pseudocubic perovskite cell) orientation were fabricated by Templated Grain Growth (TGG) or Reactive Templated Grain Growth (RTGG) using anisotropically shaped template particles. In the case of TGG, molten salt synthesized SrTiO3 platelets were tape cast with a (Na1/2Bi1/2)TiO3-5.5mol%BaTiO3 powder and sintered at 1200°C for up to 12 hours. For the RTGG approach, Bi4Ti3O12 (BiT) platelets were tape cast with a Na2CO3, Bi2O3, TiO 2, and BaCO3 powder mixture and reactively sintered. The TGG approach using SrTiO3 templates gave stronger texture along [001] compared to the RTGG approach using BiT templates. The textured ceramics were characterized by X-ray and electron backscatter diffraction for the quality of texture. The texture function was quantified by the Lotgering factor, rocking curve, pole figures, inverse pole figures, and orientation imaging microscopy. Electrical and electromechanical property characterization of randomly oriented and pc textured (Na1/2Bi1/2)TiO 3-5.5 mol% BaTiO3 rhombohedral ceramics showed 0.26% strain at 70 kV/cm, d33 coefficients over 500 pC/N have been obtained for highly textured samples (f ˜ 90%). The piezoelectric coefficient from Berlincourt was d33 ˜ 200 pC/N. The materials show considerable hysteresis. The presence of hysteresis in the unipolar-electric field curve is probably linked to the ferroelastic phase transition seen in the (Na 1/2Bi1/2)TiO3 system on cooling from high temperature at ˜520°C. The macroscopic physical properties (remanent polarization, dielectric constant, and piezoelectric coefficient) of random and textured ([001] pc) rhombohedral perovskites were estimated by linear averaging of single

  9. The formation and evolution of planetary systems: Grain growth and chemical processing of dust in T Tauri systems

    CERN Document Server

    Bouwman, J; Hillenbrand, L A; Meyer, M R; Pascucci, I; Carpenter, J; Hines, D; Kim, J S; Silverstone, M D; Hollenbach, D; Wolf, S

    2008-01-01

    This paper is one in a series presenting results obtained within the Formation and Evolution of Planetary Systems (FEPS) Legacy Science Program on the Spitzer Space Telescope. Here we present a study of dust processing and growth in seven protoplanetary disks. Our spectra indicate that the circumstellar silicate dust grains have grown to sizes at least 10 times larger than observed in the interstellar medium, and show evidence for a non-negligible (~5 % in mass fractions) contribution from crystalline species. These results are similar to those of other studies of protoplanetary disks. In addition, we find a correlation between the strength of the amorphous silicate feature and the shape of the spectral energy distribution. This latter result is consistent with the growth and subsequent gravitational settling of dust grains towards the disk mid-plane. Further, we find a change in the relative abundance of the different crystalline species: more enstatite relative to forsterite is observed in the inner warm du...

  10. A Novel Hybrid Ultramicrotomy/FIB-SEM Technique: Preparation of Serial Electron-Transparent Thin Sections of a Hayabusa Grain

    Science.gov (United States)

    Berger, Eve L.; Keller, Lindsay P.

    2014-01-01

    The Japanese space agency's (JAXA) Hayabusa mission returned the first particulate samples (typically SEM). Using a diamond trim knife, the epoxy surrounding the grain is removed on 3 sides (to within a few microns of the grain); the depth of material removed extends well below the bottom of the particle. The sample is attached to an SEM pin mount, the epoxy coated with conductive paint, and the entire assembly coated with approx. 40nm of carbon to eliminate sample charging during FIB work. A protective carbon cap is placed according to the plan for the 15 FIB sections. The central 'spine' of the cap runs perpendicular to the front of the sample, and the 'ribs' protruding from either side run parallel. Each rib indicates the location of a planned FIB section, and the spine contains the final two planned sections. We use a cap with a 4 micron-wide spine and 2micron-wide ribs that have ?3.5 micron of space between them (narrower cuts result in too much re-deposition of material inside the trenches). Using a 30kV, 3nA ion-beam we expose the front surface of the grain and commence milling trenches between sections. Rather than using the typical C-cut to prepare the sample for lift-out, an L-cut is used instead, leaving the sample connected by an interior tab. tab. Sections are lifted out, attached to TEM grids and thinned to electron transparency. TEM analyses show that our hybrid technique preserves both interior and edge features, including surface modifications from exposure to the space environment, such as damaged rims that form in response to solar wind implantation effects and adhering grains. In addition, the FIB sections provide larger areas that are free of fractures and chatter effects in comparison to the microtome thin sections, thus enabling more accurate measurements of solar flare particle track densities that are used to determine the surface exposure age of the particles.

  11. Prebiotic Content of Bread Prepared with Flour from Immature Wheat Grain and Selected Dextran-Producing Lactic Acid Bacteria

    Science.gov (United States)

    Ventorino, Valeria; Cavella, Silvana; Fagnano, Massimo; Brugno, Rachele

    2013-01-01

    In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type “0 America” wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB), Leuconostoc lactis A95 and Lactobacillus curvatus 69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 ± 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 ± 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as L. lactis, L. curvatus, and Pediococcus acidilactici. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 ± 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 ± 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages

  12. Prebiotic content of bread prepared with flour from immature wheat grain and selected dextran-producing lactic acid bacteria.

    Science.gov (United States)

    Pepe, Olimpia; Ventorino, Valeria; Cavella, Silvana; Fagnano, Massimo; Brugno, Rachele

    2013-06-01

    In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type "0 America" wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB), Leuconostoc lactis A95 and Lactobacillus curvatus 69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 ± 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 ± 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as L. lactis, L. curvatus, and Pediococcus acidilactici. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 ± 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 ± 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages of

  13. Temperature dependence growth of CdO thin film prepared by spray pyrolysis

    Directory of Open Access Journals (Sweden)

    Hassan H. Afify

    2014-09-01

    Full Text Available CdO thin films prepared by spray pyrolysis technique show temperature dependence growth when the spray time is constant. In contrast, the growth is film thickness dependent when the substrate temperature is constant. The films are polycrystalline in the covered spray time and substrate temperature ranges. The crystallite size and microstrain are calculated and analyzed. The Atomic Force Microscopy (AFM micrographs prove that the grains are uniformly distributed within the scanning areas (5 μm × 5 μm and (50 μm × 50 μm. The roughness shows a considerable decrease with substrate temperature. All samples show an abrupt change in transmission which indicates a direct transition and good crystallinity. The transmission of films is increased up to 80% with increasing substrate temperature in wavelength ranged from 450 nm to 1000 nm. Also, a broad absorption band is observed in the range 1500–2000 nm. This band could be attributed to the increase in free carrier concentration which confirmed by a reasonable decrease in the film sheet resistance. The band gap Eg is determined and found to be in the range 2.45–2.55 eV. The sheet resistance is reduced with increasing deposition temperature due to the increase in free carrier concentration and found to be 66 Ω/□ at 450 °C.

  14. First-order Description of the Mechanical Fracture Behavior of Fine-Grained Surficial Marine Sediments During Gas Bubble Growth

    Science.gov (United States)

    2010-01-01

    10 F04O29 BARRY ET AL.: BUBBLE GROWTH BY FRACTURE P04029 Figure 3. Map of field site. Canard, Nova Scotia, Canada. appears to approximate the...Bottinger. and T. Dahm (2005), Buoyancy-driven fracture ascent: Experiments in layered gelatine. J. Volcano!. Geotherm . Res., 144. 273-285. doi...Journal Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE First-order description of the mechanical fracture behavior of fine-grained

  15. Analysis Of The Austenite Grain Growth In Low-Alloy Boron Steel With High Resistance To Abrasive Wear

    Directory of Open Access Journals (Sweden)

    Białobrzeska B.

    2015-09-01

    Full Text Available Today low-alloy steels with boron achieve high resistance to abrasive wear and high strength. These features are obtained by using advanced technology of manufacturing. This makes boron steels increasingly popular and their application more diverse. Application of these steels can extend the lifetime of very expensive machine construction in many industries such as mining, the automotive, and agriculture industries. An interesting subgroup of these materials is steel with boron intended for heat treatment. These steels are supplied by the manufacturer after cold or hot rolling so that it is possible for them to be heat treated in a suitable manner by the purchaser for its specific application. Very important factor that determines the mechanical properties of final product is austenite grain growth occurring during hot working process such us quenching or hot rolling. Investigation of the effect of heating temperature and holding time on the austenite grain size is necessary to understand the growth behavior under different conditions. This article presents the result of investigation of austenite grain growth in selected low-allow boron steel with high resistance to abrasive wear and attempts to describe the influence of chemical composition on this process.

  16. Raman imaging of grain growth mechanism in highly textured Pb(Mg{1{/}3}Nb{2{/}3})O{3}-PbTiO{3} piezoelectric ceramics*

    Science.gov (United States)

    Colomban, P.; Pham Thi, Mai

    2005-06-01

    Pb(Mg{1 / 3}Nb{2 / 3})O{3}-PbTiO{3} solid solution ((1-x)PMN-xPT) tape cast ceramics have been prepared by homo-epitaxial templated grain growth (HTGG) using cubic 0.75PMN 0.25 PT single crystal seeds as template (a few wt%) and x = 0.35 nanoparticles for the ceramic matrix. Raman imaging studied representative medium and highly textured ceramics. On the base of a previous study which has shown that the Raman peak centre of gravity depends on the solid solution composition whereas peak intensity is correlated to the unit-cell distortion, Raman imaging shows that the final composition and structure is very close to that of the matrix.

  17. [Influence of drought on leaf photosynthetic capacity and root growth of soybeans at grain filling stage].

    Science.gov (United States)

    Guo, Shu-jin; Yang, Kai-min; Huo, Jin; Zhou, Yong-hang; Wang, Yan-ping; Li, Gui-quan

    2015-05-01

    A drought-resistant soybean cultivar Jinda 70 and a drought-sensitive soybean cultivar Jindou 26 were taken as test materials. At the grain filling stage, the cultivars were subject to three water treatments including sufficient water supply, light drought stress, and severe drought stress by using pot experiments for research on influence of drought on leaf photosynthetic capacity and root growth of soybeans. The results showed that as the degree of drought stress was aggravated, all of the indices including leaf area, chlorophyll content, net photosynthetic rates (Pn), stomatal conductance (g(s)), transpiration rate (Tr), intercellular CO2 concentration (Ci), plant mass, plant height, seed yield, and harvest index in the two cultivars declined. The root length and root mass increased under light drought stress, and decreased under severe drought stress. Root-shoot ratio ascended as the degree of drought stress was aggravated. Under severe drought stress, the increase of root-shoot ratio of the drought-resistant soybean cultivar Jinda 70 was up to 135.7%, which was higher than the that (116.7%) of the drought-sensitive soybean cultivar Jindou 26. Simultaneously, leaf area and chlorophyll content in Jinda 70 were respectively 69.3% and 85.5% of those in the control, which were better than those of Jindou 26. g(s) and Pn of Jinda 70 respectively declined 67.9% and 77.9%, but still lower than those of Jindou 26. Therefore, the decline range of harvest index of Jinda 70 was 43.8%, which was lower than the range of 78.8% of Jindou 26. The Biplot revealed that under different dry treatments, there were significant positive correlations among the six indexes including leaf area, chlorophyll content, Pn, g(s), Tr, and Ci of the two cultivars. There were also significant positive correlations among the six indices including plant mass, plant height, root length, root mass, seed yield, and harvest index. Root-shoot ratio only had significant positive correlation with root

  18. Using pollen grains as novel hydrophilic solid-phase extraction sorbents for the simultaneous determination of 16 plant growth regulators.

    Science.gov (United States)

    Lu, Qian; Wu, Jian-Hong; Yu, Qiong-Wei; Feng, Yu-Qi

    2014-11-01

    In this article, pollen grains were for the first time used as a hydrophilic solid-phase extraction (HILIC-SPE) sorbent for the determination of 16 plant growth regulators (PGRs) in fruits and vegetables. Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM) and nitrogen sorption porosimetry (NSP) were used to investigate the chemical structure and the surface properties of the pollen grains. Pollen grains exhibited an excellent adsorption capacity for some polar compounds due to their particular functional groups. Several parameters influencing extraction performance were investigated. A green and simple HILIC-SPE-method using pollen grain cartridge for purification of fruit and vegetable extractions, followed by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) was established. Good linear relationships were obtained for 16 PGRs with correlation coefficients (R) above 0.9980. The limits of detection (LODs) of 16 PGRs in cucumber were in the range of 0.01-1.10 μg · kg(-1). Reproducibility of the method was evaluated by intra-day and inter-day precisions with relative standard deviations (RSDs), which were less than 14.4%. We successfully applied this methodology to analyze 16 PGRs in 8 different kinds of fruits and vegetables. The recoveries from samples spiked with 16 PGRs were from 80.5% to 119.2%, with relative standard deviations less than 15.0%.

  19. Establishment of growth medium and quantification of pollen grains of olive cultivars in Brazil's subtropical areas

    Directory of Open Access Journals (Sweden)

    Luiz Fernando de Oliveira da Silva

    2015-01-01

    Full Text Available ABSTRACT Pollen grain germination in vitro indicates viability and consequently provides information related to fruit set. It also assists in the development of hybrids. Along with a suitable species, a standard culture medium is essential for evaluating pollen viability. It should contain a gelling agent consisting of carbohydrates and enhancer elements as well as have the correct pH, temperature, and incubation time. The objective of this study was to optimise the culture medium, determine the pollen germination capacity, and quantify the number of pollen grains per flower of certain olive tree cultivars. A basic sequential culture medium for pollen grain germination was determined, always utilizing the best result from the previous experiment to continue the sequence.The factorial treatment arrangement was: 1 agar versus boric acid; 2 pH versus sucrose; 3 calcium nitrate versus magnesium sulfate. After determining the culture medium components, two experiments were conducted evaluating temperature and incubation time. Another experiment evaluated both the germination percentage and the number of flower pollen grains of 28 cultivars. The culture medium should be composed of 4 g∙L-1 of agar, 90 g∙L-1 of sucrose, and 400 mg∙L-1 of boric acid with a pH adjusted to 5.79 and an incubation time of 60 h at 28 °C. The Manzanilla 215 cultivar had the highest germination rate while Ascolano 315 presented the highest number of pollen grains per flower.

  20. Novel hard materials with controlled (W0.5Al0.5)C grain shapes: in-situ high pressure preparation and mechanical properties

    Institute of Scientific and Technical Information of China (English)

    Zhuhui QIAO; Xianfeng MA; Huaguo TANG; Wei ZHAO; Jianwei LIU

    2012-01-01

    A novel hard material with various (W0.5Al0.5)C grain shapes was successfully prepared through mechanical alloying and in-situ high-pressure sintering process.X-ray diffraction apparatus and scanning electron microscopy were used to characterize the phase and the microstructures of the samples.The novel hard materials with “fibrous”,“rounded” and “plate-like” grains,which do not contain sharp edges,have the improved mechanical properties.The bulk boundless (W0.5Al0.5)C hard material with various (W0.5Al0.5)C grain shapes possesses good mechanical properties and light weight.The formation mechanism for the non-equilibrium (W0.5Al0.5)C grains during in-situ high-pressure sintering is also discussed.

  1. Physics Teacher Preparation as a Means for Growth

    Science.gov (United States)

    Henderson, Ron

    2013-03-01

    Physics departments across the country are experiencing pressures to increase the number of graduates. One response is to improve marketing and recruiting efforts to add students to existing pipelines. A more innovative approach is to create new pathways tied to career paths that are alternatives to graduate school. One occupation that currently needs more graduates than physics departments are supplying is physics teaching. About 3 years ago, MTSU began implementing a strategy to prepare physics majors for careers in high school teaching. These efforts included developing coursework specifically related to physics teaching, creating relationships with the college of education, moving to pedagogies that reflect physics education research (PER)-validated best practices, hiring a tenure-track PER expert, implementing new ways to reach potential majors, and seeking external funding. The cumulative result has not only added a number of physics teaching majors to our roles, but has affected our existing programs in a manner that has yielded further growth. Support provided by the APS/AAPT PhysTEC project.

  2. Drought priming at vegetative growth stages improves tolerance to drought and heat stresses occurring during grain filling in spring wheat

    DEFF Research Database (Denmark)

    Wang, Xiao; Vignjevic, Marija; Liu, Fulai

    2015-01-01

    Plants of spring wheat (Triticum aestivum L. cv. Vinjett) were exposed to moderate water deficit at the vegetative growth stages six-leaf and/or stem elongation to investigate drought priming effects on tolerance to drought and heat stress events occurring during the grain filling stage. Compared......Plants of spring wheat (Triticum aestivum L. cv. Vinjett) were exposed to moderate water deficit at the vegetative growth stages six-leaf and/or stem elongation to investigate drought priming effects on tolerance to drought and heat stress events occurring during the grain filling stage....... Comparedwith the non-primed plants, drought priming could alleviate photo-inhibition in flag leaves caused by drought and heat stress episodes during grain filling. In the primed plants, drought stress inhibited photosynthesis mainly through decrease of maximum photosynthetic electron transport rate, while...... decrease of the carboxylation efficiency limited photosynthesis under heat stress. The higher saturated net photosynthetic rate of flag leaves coincidedwith the lowered nonphotochemical quenching rates in the twice-primed plants under drought stress and in the primed plants during stem elongation under...

  3. Effects of Genotype and Growth Temperature on the Contents of Tannin, Phytate and In Vitro Iron Availability of Sorghum Grains.

    Directory of Open Access Journals (Sweden)

    Gangcheng Wu

    Full Text Available It has been predicted that the global temperature will rise in the future, which means crops including sorghum will likely be grown under higher temperatures, and consequently may affect the nutritional properties.The effects of two growth temperatures (OT, day/night 32/21°C; HT 38/21°C on tannin, phytate, mineral, and in vitro iron availability of raw and cooked grains (as porridge of six sorghum genotypes were investigated.Tannin content significantly decreased across all sorghum genotypes under high growth temperature (P ≤0.05, while the phytate and mineral contents maintained the same level, increased or decreased significantly, depending on the genotype. The in vitro iron availability in most sorghum genotypes was also significantly reduced under high temperature, except for Ai4, which showed a pronounced increase (P ≤0.05. The cooking process significantly reduced tannin content in all sorghum genotypes (P ≤0.05, while the phytate content and in vitro iron availability were not significantly affected.This research provides some new information on sorghum grain nutritional properties when grown under predicted future higher temperatures, which could be important for humans where sorghum grains are consumed as staple food.

  4. Box-scan: A novel 3DXRD method for studies of recrystallization and grain growth

    DEFF Research Database (Denmark)

    Lyckegaard, Allan; Poulsen, Henning Friis; Ludwig, Wolfgang;

    2012-01-01

    Within the last decade a number of x-ray diffraction methods have been presented for non-destructive 3D characterization of polycrystalline materials. 3DXRD [1] and Diffraction Contrast Tomography [2,3,4] are examples of such methods providing full spatial and crystallographic information...... of the individual grains. Both methods rely on specially designed high-resolution near-field detectors for acquire the shape of the illuminated grains, and therefore the spatial resolution is for both methods limited by the resolution of the detector, currently ~2 micrometers. Applying these methods using...... conventional far-field detectors provides information on centre of mass, crystallographic orientation and stress state of the individual grains [5], at the expense of high spatial resolution. However, far-field detectors have much higher efficiency than near-field detectors, and as such are suitable...

  5. Evidence and analysis of parallel growth mechanisms in Cu{sub 2}O films prepared by Cu anodization

    Energy Technology Data Exchange (ETDEWEB)

    Caballero-Briones, F., E-mail: fcaballerobriones@ub.ed [Department of Physical Chemistry, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); CIBER-BBN, Maria de Luna 11, 50018 Zaragoza (Spain); Palacios-Padros, A. [Department of Physical Chemistry, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Calzadilla, O. [Facultad de Fisica, Universidad de La Habana, San Lazaro y L, Colina Universitaria, 10400 Vedado, La Habana (Cuba); Sanz, Fausto, E-mail: fsanz@ub.ed [Institute for Bioengineering of Catalonia (IBEC), Edifici Helix, Baldiri i Reixac 15-21, 08028 Barcelona (Spain); Department of Physical Chemistry, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); CIBER-BBN, Maria de Luna 11, 50018 Zaragoza (Spain)

    2010-05-30

    We have studied the preparation of Cu{sub 2}O films by copper anodization in a 0.1 M NaOH electrolyte. We identified the potential range at which Cu{sup +} dissolution takes place then we prepared films with different times of exposure to this potential. The morphology, crystalline structure, band gap, Urbach energy and thickness of the films were studied. Films prepared with the electrode unexposed to the dissolution potential have a pyramidal growth typical of potential driven processes, while samples prepared at increasing exposure times to dissolution potential present continuous nucleation, growth and grain coalescence. We observed a discrepancy in the respective film thicknesses calculated by coulometry, atomic force microscopy and optical reflectance. We propose that anodic Cu{sub 2}O film formation involves three parallel mechanisms (i) Cu{sub 2}O nucleation at the surface, (ii) Cu{sup +} dissolution followed by heterogeneous nucleation and (iii) Cu{sup +} and OH{sup -} diffusion through the forming oxide and subsequent reaction in the solid state.

  6. Towards the Truly Predictive 3D Modeling of Recrystallization and Grain Growth in Advanced Technical Alloys

    Science.gov (United States)

    2010-06-11

    Barrales- Mora , D.A. Molodov *, G. Gottstein Acta Mater. 56 (2008) 4998. [12] D.A. Molodov, A.D. Sheikh-Ali, Acta Mater. 52 (2004) 4377. [13] D.A...Science and Engineering: A493, (2008), Pages 33-40. 22. L. Van Brutzel, E. Vincent -Aublant, Grain boundary influence on displacement cascades in UO2: A...33-40. 39. L. Van Brutzel, E. Vincent -Aublant, Grain boundary influence on displacement cascades in UO2: A molecular dynamics study, Journal of

  7. Correlating whisker growth and grain structure on Sn-Cu samples by real-time scanning electron microscopy and backscattering diffraction characterization

    Energy Technology Data Exchange (ETDEWEB)

    Pei Fei; Jadhav, Nitin; Chason, Eric [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States)

    2012-05-28

    Whiskers/hillocks grow out of Pb-free Sn coatings used in electronics manufacturing. To determine which grains form whiskers/hillocks, we use scanning electron microscopy and backscattering diffraction to simultaneously monitor the surface morphology and grain structure. To reduce surface roughness, we developed a ''peel-off'' method to prepare ultra-flat samples that were measured repeatedly while whiskers/hillocks formed. We find grains that form into whiskers/hillocks are present in the as-deposited film (i.e., not re-nucleated) and many have horizontal grain boundaries beneath them. Grain rotation during whisker/hillock formation means that measurements performed after the features grow do not indicate their initial grain orientations.

  8. Effect of Pt Concentration on the Grain Growth of TiO2sol-gel Films

    Directory of Open Access Journals (Sweden)

    Jia Y.J.

    2017-01-01

    Full Text Available Pt metallic has been supported on TiO2 surface using different methods, Here, Pt doped TiO2 (Pt-TiO2 sol gel thin film were successfully produced by reducing chloroplatinc acid (H2PtCl6. The structures of prepared composites were investigated using X-ray diffraction (XRD. The physical morphologies of the composites were examined using transmission electron microscope (TEM. The grain size of Pt-TiO2 thin film after annealing was also measured by atomic force microscope (AFM images.

  9. Mesoporous PbI2 assisted growth of large perovskite grains for efficient perovskite solar cells based on ZnO nanorods

    Science.gov (United States)

    Li, Shibin; Zhang, Peng; Chen, Hao; Wang, Yafei; Liu, Detao; Wu, Jiang; Sarvari, Hojjatollah; Chen, Zhi David

    2017-02-01

    Perovskite solar cells (PSCs) have attracted great attention due to their low cost and high power conversion efficiency (PCE). However, the defects and grain boundaries in perovskite films dramatically degrade their performance. Here, we show a two-step annealing method to produce mesoporous PbI2 films for growth of continuous, pinhole-free perovskite films with large grains, followed by additional ethanol vapor annealing of perovskite films to reduce the defects and grain boundaries. The large perovskite grains dramatically suppress the carrier recombination, and consequently we obtain ZnO-nanorod-based PSCs that exhibit the best efficiency of 17.3%, with high reproducibility.

  10. Modeling the effect of neighboring grains on twin growth in HCP polycrystals

    Science.gov (United States)

    Kumar, M. Arul; Beyerlein, I. J.; Lebensohn, R. A.; Tomé, C. N.

    2017-09-01

    In this paper, we study the dependence of neighboring grain orientation on the local stress state around a deformation twin in a hexagonal close packed (HCP) crystal and its effects on the resistance against twin thickening. We use a recently developed, full-field elasto-visco-plastic formulation based on fast Fourier transforms that account for the twinning shear transformation imposed by the twin lamella. The study is applied to Mg, Zr and Ti, since these HCP metals tend to deform by activation of different types of slip modes. The analysis shows that the local stress along the twin boundary are strongly controlled by the relative orientation of the easiest deformation modes in the neighboring grain with respect to the twin lamella in the parent grain. A geometric expression that captures this parent-neighbor relationship is proposed and incorporated into a larger scale, mean-field visco-plastic self-consistent model to simulate the role of neighboring grain orientation on twin thickening. We demonstrate that the approach improves the prediction of twin area fraction distribution when compared with experimental observations.

  11. Curved walls: Grain growth, settling, and composition patterns in T Tauri disk dust submlimation fronts

    CERN Document Server

    McClure, M K; Calvet, N; Espaillat, C; Hartmann, L; Sargent, B; Watson, D M; Ingleby, L; Hernandez, J

    2013-01-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best-fits to the near- and mid-IR excesses are found for curved, 2-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe)=0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10^(-8) to 10^(-10) Msol/yr, the maximum grain size in the lower layer decreases from 3 to 0.5 microns. We attribute this to a decrease in fragmentation and ...

  12. Structural and Magnetic Characterizations of Nano Sized Grain Zinc Ferrite/Hydroxyapatite Ceramic Prepared by Solid State Reaction Route.

    Science.gov (United States)

    Pankaew, Piyapong; Klumdoung, Pattarinee

    2015-11-01

    A promising composite of bioactive hydroxyapatite (HAp) and zinc ferrite (ZnFe2O4) has potentials for future bone reinforcing formation. In present study, HAp and ZnFe2O4 composite ceramic was prepared by solid state reaction route for easier control of structural and magnetic characteristics and with low cost. HAp powder was synthesized by precipitation method from chicken eggshell. Mixed powders with varying ZnFe2O4/HAp weight ratios from 2-10 wt% were milled together and uniaxially pressed and then sintered at 1200 degrees C for 3 hours. The XRD results showing no other phases of composite ceramics with only HAp and ZnFe2O4 phases were identified, indicating high stability of HAp property. Phase fractions of ZnFe2O4 were found to increase from 10.8 to 18.73 wt% with increasing content of ZnFe2O4. FT-IR results were only revealed vibration bands of standard HAp phase. SEM results revealed primary grains sizes of the prepared ceramics in nano scale. The BET surface area and pore volume increased with increasing content of ZnFe2O4 in composite ceramics. The VSM results of composites with increasing ZnFe2O4 content had been shown with increasing magnetization from 0.05 to 1.85 emu/g while their coercivities were decreased from 44 to 24 Oe. Higher magnetization as well as higher super paramagnetic behavior could be achieved with increasing the studied ZnFe2O4 weight ratios in ZnFe2O4/HAp composite ceramics, which can be tailored for specific applications.

  13. The Herschel exploitation of local galaxy Andromeda (HELGA) VI: Strengthening the case for substantial interstellar grain growth

    CERN Document Server

    Mattsson, L; Andersen, A C; Smith, M W L; De Looze, I; Baes, M; Viaene, S; Gentile, G; Fritz, J; Spinoglio, L

    2014-01-01

    In this paper we consider the implications of the distributions of dust and metals in the disc of M31. We derive mean radial dust distributions using a dust map created from Herschel images of M31 sampling the entire far-infrared (FIR) peak. Modified blackbodies are fit to approximately 4000 pixels with a varying, as well as a fixed, dust emissivity index (beta). An overall metal distribution is also derived using data collected from the literature. We use a simple analytical model of the evolution of the dust in a galaxy with dust contributed by stellar sources and interstellar grain growth, and fit this model to the radial dust-to-metals distribution across the galaxy. Our analysis shows that the dust-to-gas gradient in M31 is steeper than the metallicity gradient, suggesting interstellar dust growth is (or has been) important in M31. We argue that M31 helps build a case for cosmic dust in galaxies being the result of substantial interstellar grain growth, while the net dust production from stars may be lim...

  14. The Difference in Growth and Four Microelement Concentrations Between Two Rice Genotypes Differing in Grain Cadmium-Accumulating Capacity

    Institute of Scientific and Technical Information of China (English)

    CHENG Wang-da; ZHANG Guo-ping; YAO Hai-gen; Peter Dominy; WANG Run-yi

    2004-01-01

    A pot experiment was conducted with two rice genotypes having different Cd concentrations in their grains to study the effect of soil Cd level on biomass, Cd and Fe, Zn, Cr and Pb accumulation in different plant parts. Cd was added into soil to form 4 levels, i.e.,0, 0.5, 2.5 and 12.5 mg kg-1, respectively. The results showed that the Cd-induced reduction in biomass accumulation varied in both genotypes and growth stages. The Cd-induced reduction in biomass became less with the progress of growth, and Xiushui63, a genotype with relatively higher grain Cd concentration, was more severely inhibited than Xiushui217,a relatively lower Cd concentration. Both Cd concentration and accumulation in the various plant parts increased substantially with the increase of Cd levels. The difference between two genotypes in Cd concentration and accumulation became more pronounced with increased Cd level as well as prolonged duration of exposure. Xuishui63 had much greater Cd accumulation than Xiushui217, in particular at late growth stage. Xuishui63 had a remarkably higher Cd translocation of roots to shoots than Xiushui217 in all Cd levels.The effect of Cd addition on four microelement concentrations in straw and milled rice also varied in genotypes and Cd levels. Without Cd addition, Xiushui63 was significantly lower than Xiushui217 in the concentrations of all four elements in straw, while the case was just opposite in milled rice. Zn, Fe and Pb concentrations decreased in milled rice with the increase of Cd level, although the reduction extent differed in two genotypes.The results indicated that Cd concentration in rice grain is primarily dependent on the shoot Cd concentration, which is in turn mainly determined by Cd translocation from roots to shoots.

  15. Texture design for microwave dielectric (Ca0.7Nd0.3)0.87TiO3 ceramics through reactive-templated grain growth

    Science.gov (United States)

    Tani, Toshihiko; Takeuchi, Tsuguto

    2015-06-01

    Plate-like Ca3Ti2O7 (CT) and Nd2Ti2O7 (NT) particles were synthesized in molten salts and used as reactive templates for the preparation of highly textured (Ca0.7Nd0.3)0.87TiO3 bulk ceramics (CNT) with preferred pseudocubic and orientations, respectively. During flux growth CT and NT particles developed facets parallel to the pseudocubic {100} and {110} planes, respectively, in a perovskite unit cell, since those planes correspond to the interlayers of the layered perovskite-type crystal structures. Complementary reactants for the CNT stoichiometry were wet-mixed with the reactive templates and the slurries were tape-cast. Then stacked tapes were heat-treated for dense single-phase CNT ceramics with a distorted and A-site deficient regular perovskite-type structure. The CNT ceramics prepared with CT and NT reactive templates exhibited strong pseudocubic 100- and 110-family x-ray diffraction peaks, respectively, with other peaks drastically suppressed when non-perovskite sources were used as complementary reactants. The textured ceramics possess unique microstructures; as either parallel or obliquely stacked block structures with a pseudocubic {100} plane faceted. The pseudocubic {100}-and {110}-textured CNT ceramics exhibited ∼10 and ∼20% higher products of the dielectric quality factor and frequency, Q · f, respectively, than conventional ceramic sintered at the same temperature. When Q · f is compared based on the same grain size, the {100}-textured CNT exhibited 27% higher values than non-textured while relative permittivity and temperature coefficient of resonant frequency were of similar values. Simple geometrical relationships between electric field and penetrated pseudocubic {hk0}-type grain boundaries must lead to the reduced scattering and dielectric loss.

  16. Texture design for microwave dielectric (Ca0.7Nd0.3)0.87TiO3 ceramics through reactive-templated grain growth.

    Science.gov (United States)

    Tani, Toshihiko; Takeuchi, Tsuguto

    2015-06-01

    Plate-like Ca3Ti2O7 (CT) and Nd2Ti2O7 (NT) particles were synthesized in molten salts and used as reactive templates for the preparation of highly textured (Ca0.7Nd0.3)0.87TiO3 bulk ceramics (CNT) with preferred pseudocubic 〈100〉 and 〈110〉 orientations, respectively. During flux growth CT and NT particles developed facets parallel to the pseudocubic {100} and {110} planes, respectively, in a perovskite unit cell, since those planes correspond to the interlayers of the layered perovskite-type crystal structures. Complementary reactants for the CNT stoichiometry were wet-mixed with the reactive templates and the slurries were tape-cast. Then stacked tapes were heat-treated for dense single-phase CNT ceramics with a distorted and A-site deficient regular perovskite-type structure. The CNT ceramics prepared with CT and NT reactive templates exhibited strong pseudocubic 100- and 110-family x-ray diffraction peaks, respectively, with other peaks drastically suppressed when non-perovskite sources were used as complementary reactants. The textured ceramics possess unique microstructures; as either parallel or obliquely stacked block structures with a pseudocubic {100} plane faceted. The pseudocubic {100}-and {110}-textured CNT ceramics exhibited ∼10 and ∼20% higher products of the dielectric quality factor and frequency, Q · f, respectively, than conventional ceramic sintered at the same temperature. When Q · f is compared based on the same grain size, the {100}-textured CNT exhibited 27% higher values than non-textured while relative permittivity and temperature coefficient of resonant frequency were of similar values. Simple geometrical relationships between electric field and penetrated pseudocubic {hk0}-type grain boundaries must lead to the reduced scattering and dielectric loss.

  17. Sintering process and grain growth of Mn-Zn ferrite nanoparticles

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; CUI Yinfang; WANG Yongming; HAO Shunli; LIU Chunjing

    2006-01-01

    The density, microstructure and magnetic properties of non-doped Mn-Zn ferrite nanoparticles sintered compacts were investigated. The compacts of non-doped Mn-Zn ferrite nanoparticles were sintered by segmented-sintering process at lower sintering temperature. The density of sintered samples was measured by Archimedes method, and the phase composition and microstructure were examined by XRD and SEM. The sintered Mn-Zn ferrite magnetic measurements were carried out with Vibrating Sample. The results show that the density of sintered compacts increases with the rising of sintering temperature, achieving 4.8245 g·cm-3 when sintered at 900 ℃, which is the optimal density of Mn-Zn functional ferrite needed and from the fractured surface of sintered samples, it can be seen that the grain grows well with small grain size and homogeneous distribution.

  18. Plant growth-promoting actinobacteria: a new strategy for enhancing sustainable production and protection of grain legumes.

    Science.gov (United States)

    Sathya, Arumugam; Vijayabharathi, Rajendran; Gopalakrishnan, Subramaniam

    2017-06-01

    Grain legumes are a cost-effective alternative for the animal protein in improving the diets of the poor in South-East Asia and Africa. Legumes, through symbiotic nitrogen fixation, meet a major part of their own N demand and partially benefit the following crops of the system by enriching soil. In realization of this sustainability advantage and to promote pulse production, United Nations had declared 2016 as the "International Year of pulses". Grain legumes are frequently subjected to both abiotic and biotic stresses resulting in severe yield losses. Global yields of legumes have been stagnant for the past five decades in spite of adopting various conventional and molecular breeding approaches. Furthermore, the increasing costs and negative effects of pesticides and fertilizers for crop production necessitate the use of biological options of crop production and protection. The use of plant growth-promoting (PGP) bacteria for improving soil and plant health has become one of the attractive strategies for developing sustainable agricultural systems due to their eco-friendliness, low production cost and minimizing consumption of non-renewable resources. This review emphasizes on how the PGP actinobacteria and their metabolites can be used effectively in enhancing the yield and controlling the pests and pathogens of grain legumes.

  19. (Ba,Eu)Ti03细晶粒陶瓷制备中的影响因素%Influence factors of preparing ( Ba, Eu) TiO3 fine grain ceramics

    Institute of Scientific and Technical Information of China (English)

    董耀龙; 路大勇

    2012-01-01

    (Ba1-xEux )TiO3 and (Ba1-xEux )Ti1-x/sO3 ceramics with tetragonal structure were prepared by a cold - pressing ceramic technique under the temperatures of 1 400 3C and 1 300 C ,respectively. The influence of Eu eontent,Ti-vacaney defects and sintering temperature on preparing (Ba, Eu )TiO3 fine grain ceramics were studied using X- ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscope (AFM). The results indicate that the average grain size of (Ba~_~Eu~)Ti~ _~/803 (x = 0.05) ceramics prepared under 1 300 C were less than 1 μm, but the average grain size of (Ba1 -x Eux )TiO3 ceramics prepared under 1 400 C grows to 5 μm. Whereas,at x = 0.03 ,the (Ba1-xEu3)TiO3 ceramics still can refine to 1 μm. This means that the higher sintering temperature is not the main reason for grain growth,the existence of Ti-vaeaney plays a role in suppressing grain growth. As x〉 0.07 ,the average grain size of (Ba1-xEUx)TiO3 ceramics were still greater than 5 Ixm,illustrating that the continuous increase of Eu content can not inhibit grain growth.%采用冷压陶瓷技术,分别在1400℃和1300℃制备了具有四方结构的(Ba1-xEu)TiO3和(Ba1-xEu)Ti1-x/80,陶瓷.应用x射线衍射(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究Eu含量、n空位缺陷和陶瓷化烧结温度的变化对制备(Ba,Eu)TiO,细晶粒陶瓷的影响因素.结果表明:当z=0.05时,1300'1:制备的(Ba1-xEu)Ti,-x/80,陶瓷细化到平均晶粒尺寸小于1μm,1400℃制备的(BahEu,)Ti03陶瓷却畸变生长到5斗m.而x=0.03时,(Ba1-xEu)TiO,陶瓷仍能细化到1μm.说明较高的陶瓷化烧结温度并不是晶粒生长的主要原因,Ti空位的存在起到抑制晶粒生长的作用.x≥0.07时,(Ba1-xEu)TiO,陶瓷为大于5斗m的粗晶粒陶瓷,说明Eu含量的继续增加不能抑制晶粒生长.

  20. Selective Growth of Low Stored Energy Grains During δ Sub-solvus Annealing in the Inconel 718 Nickel-Based Superalloy

    Science.gov (United States)

    Agnoli, Andrea; Bernacki, Marc; Logé, Roland; Franchet, Jean-Michel; Laigo, Johanne; Bozzolo, Nathalie

    2015-09-01

    The microstructure stability during δ sub-solvus annealing in Inconel 718 was investigated, focusing on the conditions that may lead to the development of very large grains (about 100 μm) in a recrystallized fine grained matrix (4 to 5 μm) despite the presence of second-phase particles. Microstructure evolution was analyzed by EBSD (grain size, intragranular misorientation) and SEM ( δ phase particles). Results confirm that, in the absence of stored energy, the grain structure is controlled by the δ phase particles, as predicted by the Smith-Zener equation. If the initial microstructure is strained ( ɛ < 0.1) before annealing, then low stored energy grains grow to a large extent, despite the Zener pinning forces exerted by the second-phase particles on the grain boundaries. Those selectively growing grains could be those of the initial microstructure that were the least deformed, or they could result from a nucleation process. The balance of three forces acting on boundary migration controls the growth process: if the sum of capillarity and stored energy driving forces exceeds the Zener pinning force, then selective grain growth occurs. Such phenomenon could be simulated, using a level set approach in a finite element context, by taking into account the three forces acting on boundary migration and by considering a realistic strain energy distribution (estimated from EBSD measurements).

  1. Effect of Plant Growth Promoting Rhizobacteria (PGPR on Phenological Traits, Grain Yield and Yield Components of Three Maize (Zea mays L. Cultivars

    Directory of Open Access Journals (Sweden)

    A Soleimani Fard

    2013-11-01

    Full Text Available To evaluate the effect of bio-fertilize on yield and its components in maize cultivars, an split plot experiment based on randomized complete bock design with three replications in was conducted in Payam-noor University of Ilam, Iran, in 2009-2010. Treatments were cultivar (SC604, SC704 and SC807 assigned to main plots and bio-fertilizer (non- inoculation, inoculation with Azetobacter, Azospirillum and dual inoculation ofAzotobacterand Azospirillum to subplots. The effect of cultivar on days to maturity, plant height, dry matter, ear length, stem diameter, number of grain per ear row, 1000-grain weight, grain yield, biological yield and protein content was significant cultivar. SC 704 had the highest dry matter (259.5 g.m-2, plant height (201.1 cm, number of grain per ear row (42.8 grain, grain yield (10850 kg.m-2, and biological yield (22040 kg.m-2. The effect of plant growth promoting rhizobacteria on all traits expect harvest index was significant. Dual inoculation ofAzotobacterand Azospirillum had the longest days to ear initiation (71.2 days, days to maturity (115.4 day, number of leaves above ear (5.6 ear, dry matter (240.4 g.m-2, ear length (24.3 cm, plant height (212.4 cm, seed number of rows per ear (14.5 row, number of grains per row (44.2 grain, grain yield (10190 kg.m-2, biological yield (21320 kg.m-2 and protein content (10.7%. Interaction effect of cultivar× plant growth promoting rhizobacteria on grain yield was significant. The highest and lowest grain yield was obtained from SC 704 and application of dual inoculation ofAzotobacterand Azospirillum (12320 kg.ha-1 and lowest from SC 604 when inoculation treatments were not used 7570 kg.ha-1 respectively.

  2. Zirconium Carbide Produced by Spark Plasma Sintering and Hot Pressing: Densification Kinetics, Grain Growth, and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Xialu Wei

    2016-07-01

    Full Text Available Spark plasma sintering (SPS has been employed to consolidate a micron-sized zirconium carbide (ZrC powder. ZrC pellets with a variety of relative densities are obtained under different processing parameters. The densification kinetics of ZrC powders subjected to conventional hot pressing and SPS are comparatively studied by applying similar heating and loading profiles. Due to the lack of electric current assistance, the conventional hot pressing appears to impose lower strain rate sensitivity and higher activation energy values than those which correspond to the SPS processing. A finite element simulation is used to analyze the temperature evolution within the volume of ZrC specimens subjected to SPS. The control mechanism for grain growth during the final SPS stage is studied via a recently modified model, in which the grain growth rate dependence on porosity is incorporated. The constant pressure specific heat and thermal conductivity of the SPS-processed ZrC are determined to be higher than those reported for the hot-pressed ZrC and the benefits of applying SPS are indicated accordingly.

  3. Application of essential oils in maize grain: impact on Aspergillus section Flavi growth parameters and aflatoxin accumulation.

    Science.gov (United States)

    Bluma, Romina V; Etcheverry, Miriam G

    2008-04-01

    The antifungal activity of Pimpinella anisum L. (anise), Pëumus boldus Mol (boldus), Hedeoma multiflora Benth (mountain thyme), Syzygium aromaticum L. (clove), and Lippia turbinate var. integrifolia (griseb) (poleo) essential oils (EOs) against Aspergillus section Flavi was evaluated in sterile maize grain under different water activity (a(w)) condition (0.982, 0.955, and 0.90). The effect of EOs added to maize grains on growth rate, lag phase, and aflatoxin B(1) (AFB(1)) accumulation of Aspergillus section Flavi were evaluated at different water activity conditions. The five EOs analyzed have been shown to influence lag phase and growth rate. Their efficacy depended mainly on the essential oil concentrations and substrate water activity conditions. All EOs showed significant impact on AFB(1) accumulation. This effect was closely dependent on the water activity, concentration, and incubation periods. Important reduction of AFB(1) accumulation was observed in the majority of EO treatments at 11 days of incubation. Boldus, poleo, and mountain thyme EO completely inhibited AFB(1) at 2000 and 3000 microg g(-1). Inhibition of AFB(1) accumulation was also observed when aflatoxigenic isolates grew with different concentration of EOs during 35 days.

  4. Growth temperature and genotype both play important roles in sorghum grain phenolic composition.

    Science.gov (United States)

    Wu, Gangcheng; Johnson, Stuart K; Bornman, Janet F; Bennett, Sarita J; Clarke, Michael W; Singh, Vijaya; Fang, Zhongxiang

    2016-02-24

    Polyphenols in sorghum grains are a source of dietary antioxidants. Polyphenols in six diverse sorghum genotypes grown under two day/night temperature regimes of optimal temperature (OT, 32/21 °C and high temperature (HT, 38/21 °C) were investigated. A total of 23 phenolic compounds were positively or tentatively identified by HPLC-DAD-ESIMS. Compared with other pigmented types, the phenolic profile of white sorghum PI563516 was simpler, since fewer polyphenols were detected. Brown sorghum IS 8525 had the highest levels of caffeic and ferulic acid, but apigenin and luteolin were not detected. Free luteolinidin and apigeninidin levels were lower under HT than OT across all genotypes (p ≤ 0.05), suggesting HT could have inhibited 3-deoxyanthocyanidins formation. These results provide new information on the effects of HT on specific polyphenols in various Australian sorghum genotypes, which might be used as a guide to grow high antioxidant sorghum grains under projected high temperature in the future.

  5. Influence of Al sub 2 O sub 3 nanoparticles on the thermal stability of ultra-fine grained copper prepared by high pressure torsion

    CERN Document Server

    Cizek, J; Kuzel, R; Islamgaliev, R K

    2002-01-01

    Ultra-fine grained (UFG) Cu (grain size 80 nm) containing 0.5 wt.% Al sub 2 O sub 3 nanoparticles (size 20 nm) was prepared by high pressure torsion (HPT). Positron lifetime spectroscopy was employed to characterize the microstructure of this material, especially with respect to types and concentration of lattice defects. The evolution of microstructure with increasing temperature was studied by positron lifetime spectroscopy and x-ray diffraction measurements. The thermal stability of the Cu + 0.5 wt.% Al sub 2 O sub 3 nanocomposite was compared with that of pure UFG Cu prepared by the same technique. The processes taking place during thermal recovery of the initial nanoscale structure in both studied materials are described. (author)

  6. INFRARED SPECTROSCOPIC SURVEY OF THE QUIESCENT MEDIUM OF NEARBY CLOUDS. I. ICE FORMATION AND GRAIN GROWTH IN LUPUS

    Energy Technology Data Exchange (ETDEWEB)

    Boogert, A. C. A. [IPAC, NASA Herschel Science Center, Mail Code 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Chiar, J. E. [SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, CA 94043 (United States); Knez, C.; Mundy, L. G. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Öberg, K. I. [Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Pendleton, Y. J. [Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Tielens, A. G. G. M.; Van Dishoeck, E. F., E-mail: aboogert@ipac.caltech.edu [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2013-11-01

    Infrared photometry and spectroscopy (1-25 μm) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of grains and the composition of ices before they are incorporated into circumstellar envelopes and disks. H{sub 2}O ices form at extinctions of A{sub K} = 0.25 ± 0.07 mag (A{sub V} = 2.1 ± 0.6). Such a low ice formation threshold is consistent with the absence of nearby hot stars. Overall, the Lupus clouds are in an early chemical phase. The abundance of H{sub 2}O ice (2.3 ± 0.1 × 10{sup –5} relative to N{sub H}) is typical for quiescent regions, but lower by a factor of three to four compared to dense envelopes of young stellar objects. The low solid CH{sub 3}OH abundance (<3%-8% relative to H{sub 2}O) indicates a low gas phase H/CO ratio, which is consistent with the observed incomplete CO freeze out. Furthermore it is found that the grains in Lupus experienced growth by coagulation. The mid-infrared (>5 μm) continuum extinction relative to A{sub K} increases as a function of A{sub K}. Most Lupus lines of sight are well fitted with empirically derived extinction curves corresponding to R{sub V} ∼ 3.5 (A{sub K} = 0.71) and R{sub V} ∼ 5.0 (A{sub K} = 1.47). For lines of sight with A{sub K} > 1.0 mag, the τ{sub 9.7}/A{sub K} ratio is a factor of two lower compared to the diffuse medium. Below 1.0 mag, values scatter between the dense and diffuse medium ratios. The absence of a gradual transition between diffuse and dense medium-type dust indicates that local conditions matter in the process that sets the τ{sub 9.7}/A{sub K} ratio. This process is likely related to grain growth by coagulation, as traced by the A{sub 7.4}/A{sub K} continuum extinction ratio, but not to ice mantle formation. Conversely, grains acquire ice mantles before the process of coagulation starts.

  7. Preparation of Copper (Cu)-Nickel (Ni) Alloy Thin Films for Bilayer Graphene Growth

    Science.gov (United States)

    2016-02-01

    10. SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release... morphological changes in the metal surfaces such as roughness, grain size, and crystal orientation due to the effects of annealing temperature, hydrogen...Ni thin film a) sputtered at 5 mT and 25 °C and b) sputtered at 15 mT and 400 °C 3.2 Grain Growth Characterization The morphology of the as

  8. Two-dimensional versus three-dimensional post-deposition grain growth in epitaxial oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bachelet, R. [Science des Procedes Ceramiques et de Traitements de Surface - CNRS UMR 6638, ENSCI, 47-73 Avenue Albert Thomas 87065 Limoges Cedex (France); Boulle, A. [Science des Procedes Ceramiques et de Traitements de Surface - CNRS UMR 6638, ENSCI, 47-73 Avenue Albert Thomas 87065 Limoges Cedex (France); Soulestin, B. [Science des Procedes Ceramiques et de Traitements de Surface - CNRS UMR 6638, ENSCI, 47-73 Avenue Albert Thomas 87065 Limoges Cedex (France); Rossignol, F. [Science des Procedes Ceramiques et de Traitements de Surface - CNRS UMR 6638, ENSCI, 47-73 Avenue Albert Thomas 87065 Limoges Cedex (France); Guinebretiere, R. [Science des Procedes Ceramiques et de Traitements de Surface - CNRS UMR 6638, ENSCI, 47-73 Avenue Albert Thomas 87065 Limoges Cedex (France)]. E-mail: r_guinebretiere@ensci.fr; Dauger, A. [Science des Procedes Ceramiques et de Traitements de Surface - CNRS UMR 6638, ENSCI, 47-73 Avenue Albert Thomas 87065 Limoges Cedex (France)

    2007-06-25

    Epitaxial thin films made of nanosized yttria-stabilized zirconia islands deposited on (0001) sapphire substrates are synthesized by sol-gel dip-coating followed by a high-temperature post-deposition thermal annealing procedure. At high temperatures, a competitive growth process takes place that allows to obtain thin films made of atomically flat islands with an in-plane diameter typically ten times higher than the thickness or on the contrary inducing the formation of dome-shaped islands. Apart from having a different shape, these islands are also characterized by a different crystallographic orientation with respect to the substrates respectively (001) and (111). In this paper, we investigate the influence of the substrate surface roughness on this competitive grain growth process. The deposition on epi-polished substrates results in a two-dimensional (2D) island growth, whereas the deposition on rough substrates results in a three-dimensional (3D) growth of dome-shaped nanosized islands. The films have been characterized by atomic force microscopy and high-resolution X-ray diffraction using the reciprocal space mapping technique.

  9. Growth, Structure and Firm Dynamics in Grain Markets: The Case of ...

    African Journals Online (AJOL)

    Optiplex 7010 Pro

    predictable business environment for traders can reduce food price instability in Ethiopia .... chances for growth and it is associated with several other attributes that make ...... About 97% of loans from formal banks in Ethiopia require property.

  10. Solvent engineering towards controlled grain growth in perovskite planar heterojunction solar cells.

    Science.gov (United States)

    Rong, Yaoguang; Tang, Zhongjia; Zhao, Yufeng; Zhong, Xin; Venkatesan, Swaminathan; Graham, Harrison; Patton, Matthew; Jing, Yan; Guloy, Arnold M; Yao, Yan

    2015-06-28

    We report an effective solvent engineering process to enable controlled perovskite crystal growth and a wider window for processing uniform and dense methyl ammonium lead iodide (MAPbI3) perovskite films. Planar heterojunction solar cells fabricated with this method demonstrate hysteresis-free performance with a power conversion efficiency around 10%. The crystal structure of an organic-based Pb iodide intermediate phase is identified for the first time, which is critical in controlling the crystal growth and optimizing thin film morphology.

  11. Fabrication of single-grain GdBa2Cu3O7− bulk superconductors with a new kind of liquid source by the top seeded infiltration and growth technique

    Indian Academy of Sciences (India)

    Guo-Zheng Li; Wan-Min Yang; Xiao-Fang Cheng; Jing Fan; Xiao-Dan Guo

    2010-05-01

    Compared to the conventional melt growth (MG) method, the top seeded infiltration and growth (TSIG) process is an effective way for preparing bulk REBa2Cu3O7− (RE-123) with finely dispersed RE2BaCuO5 (RE-211) particles. However, it is more complicated and time-consuming, because three kinds of precursor powders, namely, RE-211, RE-123 and BaCuO2, have to be prepared for the conventional TSIG process. In this paper, a new liquid source (NLS) composed of RE-211 and Ba3Cu5O8, was proposed for simplifying the TSIG process, which is different from the regular liquid source (RLS) composed of RE-123 and Ba3Cu5O8. In this modified TSIG technique, we need to prepare only RE-211 and BaCuO2 powders. Single-grain GdBa2Cu3O7− (GdBCO) bulk super-conductors have been fabricated using the RLS and NLS separately. The morphology, microstructure and levitation force of the bulk GdBCO have also been investigated. The results indicate that the NLS can be used to simplify the process flow and improve the efficiency on the fabrication of single-grain GdBCO superconductors.

  12. Preparation for microgravity science investigation of compound semiconductor crystal growth

    Science.gov (United States)

    Fripp, A. L.; Debnam, W. J.; Clark, I. O.; Crouch, R. K.; Carlson, F. M.

    1985-01-01

    Preparatory work on Bridgman directional solidification (BDS) of PbSnTe crystals prior to microgravity crystal growth experiments on Shuttle flights are reported. Gravitational effects become important in crystal growth when density gradients are present. The situation is critical in BDS of PbSnTe because of the necessity of obtaining homogeneous compositional distributions, which can be disturbed when convective processes occur. Numerical models have been defined which quantify the effects of convection in the crystal growth solution. The models were verified by earth-based crystal-growth tests in a two-zone furnace using equal concentrations of each of the elements. Data are provided to demonstrate the differences in composition among crystals grown at different orientations to the gravitational field vector.

  13. Investigation of fatigue crack growth rate of Al 5484 ultrafine grained alloy after ECAP process

    Energy Technology Data Exchange (ETDEWEB)

    Brynk, Tomasz; Rasinski, Marcin; Pakiela, Zbigniew; Kurzydlowski, Krzysztof J. [Faculty of Materials Science and Engineering, Warsaw University of Technology (Poland); Olejnik, Lech [Faculty of Production Engineering, Warsaw University of Technology (Poland)

    2010-05-15

    During the last decade equal-channel angular pressing (ECAP) has emerged as a widely used fabrication route of ultrafine-grained (UFG) metals and alloys. Enhanced mechanical properties of UFG materials produced by severe plastic deformation, with a grain size smaller than 1 {mu}m, have been reported in a large number of publications. However, the higher strength does not imply higher resistance to fatigue both high- and low-cyclic. In fact, due to reduced plasticity, higher fatigue crack propagation rates are reported for UFG materials, particularly in low-amplitude range. The aim of this work was to investigate fatigue crack propagation in samples of Al 5483 alloy subjected to ECAP treatment. Because of small dimensions of the coupons processed by ECAP, non-standard, mini-samples were used in a crack propagation tests. Two test procedures were used to estimate stress intensity factor (K). The first was based on optical measurements of crack length from images recorded during the test. The second method was based on digital image correlation (DIC), which was used to determine K value directly from displacement field near the crack tip. Comparison of these two methods is made and the relationship between the intensity of ECAP process (measured in terms of the number of ECAP passes) and fatigue crack propagation rates proposed. In addition to fatigue resistance, the results of tensile tests carried out with mini-samples are presented. Applicability of such samples in the investigations of the mechanical properties of UFG materials is discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  14. [Effects of watering and nitrogen fertilization on the growth, grain yield, and water- and nitrogen use efficiency of winter wheat].

    Science.gov (United States)

    Li, Li; Hong, Jian-Ping; Wang, Hong-Ting; Xiu, Ying-He; Zhang, Lu

    2013-05-01

    A field experiment with split-plot design was conducted to study the effects of watering, nitrogen fertilization, and their interactions on the growth, grain yield, and water- and nitrogen use efficiency of winter wheat. Four watering levels (0, 900, 1200, and 1500 m3 x hm(-2)) in main plots and five nitrogen fertilization levels (0, 90, 150, 210, and 270 kg N x hm(-2)) in sub-plots were designed. The results showed that the grain yield, nitrogen absorption, nitrogen use efficiency, and nitrogen productive efficiency of winter wheat increased with increasing level of watering, but the nitrogen use efficiency and nitrogen productive efficiency decreased with increasing nitrogen fertilization level. The grain yield, nitrogen absorption, and nitrogen harvest index were increased with increasing nitrogen fertilization level when the nitrogen application rate was 0-150 kg N x hm(-2), but not further increased significantly when the nitrogen application rate exceeded 150 kg x hm(-2). With the increasing level of watering, the water consumption amount (WCA) and the total water use efficiency increased, while the proportion of precipitation and soil water supply to WCA as well as the irrigation water use efficiency decreased. With the increasing level of nitrogen fertilization, the proportion of precipitation and watering amount to WCA increased, that of soil water supply to WCA decreased, and the total water use efficiency and irrigation water use efficiency decreased after an initial increase, with no significant differences among the treatments of 150, 210, and 270 kg N x hm(-2). It was considered that under our experimental condition, 1500 m3 x hm(-2) of watering amount plus 150 kg x hm(-2) of nitrogen fertilization could be the optimal combination for the high yielding and high efficiency.

  15. The Effect of TiO2 and B2O3 Additions on the Grain Growth of ZnO

    Science.gov (United States)

    Hardal, Gökhan; Yüksel Price, Berat

    2017-04-01

    The microstructure properties and grain growth kinetics of ZnO-B2O3-TiO2 ceramics with 0.5 and 1 mol pct doping of TiO2 were investigated. The samples were sintered at 1373 K, 1473 K, and 1573 K (1100 °C, 1200 °C, and 1300 °C) for 1, 2, and 3 hours. The bulk density and grain size of ZnO samples increased with the addition of B2O3 and TiO2. The grain size of 0.5 mol pct TiO2-doped ZnO ceramics was larger than the grain size of the 1 mol pct TiO2-doped ZnO ceramics. This is due to the increase in the ZnTi2O4 phase for the 1 mol pct TiO2-doped ZnO ceramics. The value of grain growth kinetic parameters ( n and Q) increased when the TiO2 content in ZnO ceramics increased from 0.5 to 1 mol pct. The lowest n and Q values were obtained for the 0.5 mol pct B2O3-doped ZnO samples which showed that the addition of B2O3 has a significant role on the grain growth of ZnO ceramics.

  16. Responses of Rapid Viscoanalyzer Profile and Other Rice Grain Qualities to Exogenously Applied Plant Growth Regulators under High Day and High Night Temperatures.

    Science.gov (United States)

    Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Chauhan, Bhagirath Singh; Khan, Fahad; Ihsan, Muhammad Zahid; Ullah, Abid; Wu, Chao; Bajwa, Ali Ahsan; Alharby, Hesham; Amanullah; Nasim, Wajid; Shahzad, Babar; Tanveer, Mohsin; Huang, Jianliang

    2016-01-01

    High-temperature stress degrades the grain quality of rice; nevertheless, the exogenous application of plant growth regulators (PGRs) might alleviate the negative effects of high temperatures. In the present study, we investigated the responses of rice grain quality to exogenously applied PGRs under high day temperatures (HDT) and high night temperatures (HNT) under controlled conditions. Four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA) and triazoles (Tr) were exogenously applied to two rice cultivars (IR-64 and Huanghuazhan) prior to the high-temperature treatment. A Nothing applied Control (NAC) was included for comparison. The results demonstrated that high-temperature stress was detrimental for grain appearance and milling qualities and that both HDT and HNT reduced the grain length, grain width, grain area, head rice percentage and milled rice percentage but increased the chalkiness percentage and percent area of endosperm chalkiness in both cultivars compared with ambient temperature (AT). Significantly higher grain breakdown, set back, consistence viscosity and gelatinization temperature, and significantly lower peak, trough and final viscosities were observed under high-temperature stress compared with AT. Thus, HNT was more devastating for grain quality than HDT. The exogenous application of PGRs ameliorated the adverse effects of high temperature in both rice cultivars, and Vc+Ve+MejA+Br was the best combination for both cultivars under high temperature stress.

  17. Preparation of fine-grained tungsten heavy alloys by spark plasma sintered W–7Ni–3Fe composite powders with different ball milling time

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, D.P., E-mail: dpxiang@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Ding, L. [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Li, Y.Y.; Chen, G.B. [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Zhao, Y.W. [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2013-06-15

    Highlights: ► We fabricate fine-grained W–7Ni–3Fe alloys using HEBM assisted SPS method. ► The γ-(Ni, Fe, W) phase is not observed in HEBM raw powders. ► The density of the WHAs gradually decreased with increasing HEBM time. ► The hardness and bending strength of the WHAs show different trends of variation. ► The intergranular fracture was the main bending fracture mode of the WHAs. -- Abstract: The fine-grained tungsten heavy alloys (WHAs) with grain size of about 1–3 μm were successfully prepared by spark plasma sintered W–7Ni–3Fe composite powders with different high-energy ball milling (HEBM) time. This study analyzes the effects of HEBM time not only on the composite powders but on the microstructure and mechanical properties of WHAs. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to investigate the microstructure and phase evolution rules of powders and alloys, respectively. The γ-(Ni, Fe, W) is not observed in XRD patterns of the ball milled powders. With prolonging HEBM time, the W phase diffraction peak becomes increasingly wider, and its intensity continues to decline. However, the completely amorphous structures are not formed even after HEBM 40 h. The relative density of the WHAs prepared by HEBM assisted SPS technique decreases gradually with increasing the ball milling time. For the WHAs sintered in 1150 °C for 8 min, the W grains grow finer and the content of the γ-(Ni, Fe, W) binding phase greatly increases with prolonging the HEBM time. Meanwhile, over 5 h of HEBM time, the bending strength continuously decreases and the hardness slightly increases. The intergranular fracture of the W grains is the main bending fracture mode in all the WHAs. The microporous of different sizes are distributed on the bending fracture and progressively increased with prolonging the ball milling time.

  18. An evaluation on fatigue crack growth in a fine-grained isotropic graphite

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hongtao; Sun Libin [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Li Chenfeng [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Shi Li [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Wang Haitao, E-mail: wanght@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer The propagation of micro- and macro-fatigue cracks in IG-11 graphite was studied. Black-Right-Pointing-Pointer The curves of the fatigue crack growth rate versus the SIF range show three stages. Black-Right-Pointing-Pointer The fatigue microcrack propagation is very sensitive to graphite's microstructures. Black-Right-Pointing-Pointer Graphite's microstructures have no significant impact on fatigue macrocrack growth. Black-Right-Pointing-Pointer The fatigue fracture surface indicates the fracture mechanism of the IG-11 graphite. - Abstract: The aim of this paper is to investigate the mechanism of fatigue crack propagation in IG-11 graphite, and determine the crack growth rate in relation to the stress level. Experimental studies were performed at both micro and macro scales. For fatigue microcrack propagation, single-edge-notch specimens were chosen for testing and the fatigue crack growth was measured in situ with a scanning electron microscope. For fatigue macrocrack propagation, CT specimens were used and the fatigue crack growth was measured with a high-accuracy optic microscope. Combining the two groups of experimental results, the following conclusions are derived: (1) The heterogeneous microstructures of the graphite material have significant impact on the fatigue microcrack growth, while their influence on fatigue macrocrack growth is very limited. (2) The relationship between the fatigue crack growth rate and the crack-tip stress intensity factor range can be expressed in the form of Paris formulae, which contains three stages: an initial rising part with a small slope, an abrupt rise with a very large acceleration, and a short final part with a small slope. (3) The fatigue fracture surface of the graphite material contains considerable sliding of leaf-shape graphite flakes combined with small cotton-shape plastic deformations. These sliding traces are approximately aligned at 45 Degree-Sign , showing the

  19. Nanocrystalline silicon prepared at high growth rate using helium dilution

    Indian Academy of Sciences (India)

    Koyel Bhattacharya; Debajyoti Das

    2008-06-01

    Growth and optimization of the nanocrystalline silicon (nc-Si : H) films have been studied by varying the electrical power applied to the helium diluted silane plasma in RF glow discharge. Wide optical gap and conducting intrinsic nanocrystalline silicon network of controlled crystalline volume fraction and oriented crystallographic lattice planes have been obtained at a reasonably high growth rate from helium diluted silane plasma, without using hydrogen. Improving crystallinity in the network comprising ∼ 10 nm Si-nanocrystallites and contributing optical gap widening, conductivity ascending and that obtained during simultaneous escalation of the deposition rate, promises significant technological impact.

  20. Orientation dependence of void growth at triple junction of grain boundaries in nanoscale tricrystal nickel film subjected to uniaxial tensile loading

    Science.gov (United States)

    Zhang, Yanqiu; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

    2016-11-01

    Molecular dynamics simulation was performed in order to investigate the dependence of void growth on crystallographic orientation at the triple junction of grain boundaries in nanoscale tricrystal nickel film subjected to uniaxial tensile loading. The nucleation, the emission and the transmission of Shockley partial dislocations play a predominant role in the growth of void at the triple junction of grain boundaries. The orientation factors of various slip systems are calculated according to Schmid law. The slip systems activated in a grain of tricrystal nickel film basically conform to Schmid law which is completely suitable for a single crystal. The activated slip systems play an important role in plastic deformation of nanoscale tricrystal nickel film subjected to uniaxial tensile loading. The slip directions exhibit great difference among the activated slip systems such that the void is caused to be subjected to various stress conditions, which further leads to the difference in void growth among the tricrystal nickel films with different orientation distributions. It can be concluded that the grain orientation distribution has a significant influence on void growth at the triple junction of grain boundaries.

  1. Crossing barriers in planetesimal formation: The growth of mm-dust aggregates with large constituent grains

    CERN Document Server

    Jankowski, Tim; Kelling, Thorben; Teiser, Jens; Sabolo, Walter; Gutiérrez, Pedro J; Bertini, Ivano; 10.1051/0004-6361/201218984

    2012-01-01

    Collisions of mm-size dust aggregates play a crucial role in the early phases of planet formation. We developed a laboratory setup to observe collisions of dust aggregates levitating at mbar pressures and elevated temperatures of 800 K. We report on collisions between basalt dust aggregates of from 0.3 to 5 mm in size at velocities between 0.1 and 15 cm/s. Individual grains are smaller than 25 \\mum in size. We find that for all impact energies in the studied range sticking occurs at a probability of 32.1 \\pm 2.5% on average. In general, the sticking probability decreases with increasing impact parameter. The sticking probability increases with energy density (impact energy per contact area). We also observe collisions of aggregates that were formed by a previous sticking of two larger aggregates. Partners of these aggregates can be detached by a second collision with a probability of on average 19.8 \\pm 4.0%. The measured accretion efficiencies are remarkably high compared to other experimental results. We at...

  2. Modeling the effects of N application on growth, yield and plant properties associated with the occurrence of chalky grains of rice

    Directory of Open Access Journals (Sweden)

    Hiroe Yoshida

    2016-01-01

    Full Text Available The objective of this study was to propose a model for explaining rice responses to a wide range of N application rates in various growth attributes associated with the occurrence of chalky grains. We improved the sub-model for N uptake process of a previous rice model which was originally developed for explaining genotypic and environmental variations in the whole growth processes, considering the difference in the rate of N loss from the plant-soil system between indigenously supplied soil mineral N and fertilizer N. A total of 80 growth datasets of cultivar ‘Koshihikari’ grown at Shiga prefecture, Japan, in 2010 was utilized for the calibration and validation of the model. The rice growth model well explained the above-ground biomass growth (RMSD = 78.7 g m−2 and rough dry grain yield (RMSD = 83.2 g m−2 for the validation data-set, simultaneously. The simulated carbohydrate content available per single spikelet was negatively correlated with the observed percentage of the milky-white grain which includes white-cored grain (r = −.77, p < .001 for all the data-sets of calibration and validation. On the other hand, the observed percentage of the sum of white-back and white-base grains was closely correlated with the simulated plant N content available per single spikelet (r = −.59, p < .001. It was suggested that the present rice growth model would rationally explain the effects of N application on the occurrence of the chalky grains through the dynamic change of the carbohydrate content and plant N content available per single spikelet.

  3. Prediction of grain yield using optical remote sensing and a growth model: application on Merguellil catchment (Tunisia)

    Science.gov (United States)

    Chahbi, A.; Zribi, M.; Lili-Chabaane, Z.; Duchemin, B.; Shabou, M.; Mougenot, B.; Boulet, G.

    2012-04-01

    In semi-arid region and especially in irrigated areas, agriculture represents a major contribution to food security. These areas significantly contribute to the increase of global production. A challenging objective is thus to ensure food security. Therefore an operational forecasting system for the grain yields is required and could help decision-makers to make early decisions and plan annual imports. In this context, remote sensing is a very interesting tool for giving information on the development of vegetation. The main objective is to analyze and predict the average grain yield, based on different indices measured or modelled during the growing season. Thus, we used three lines of research: the first is based on analysing a relationship between normalized vegetation index (NDVI) which is determined from optical satellite imagery and the leaf area index (LAI) measured in situ. The second axis is based on the estimation of the relation between wheat yields and normalized vegetation index NDVI. The third axis is based on the application of a growth model SAFY « Simple Algorithm For Yield Estimate » developed to simulate LAI, dry aboveground phytomass (DAM) and the grain yield (GY). For the first axis, we used optical data at high resolution. A series of 7 SPOT / HRV during the 2010-2011 agricultural seasons was acquired in the Merguellil catchment (Tunisia). At the same time we realised experimental measurements made on 27 test plots of dry or irrigated cereals carried out in study area. These measurements are mainly: the water content of the vegetation, the vegetation height, wheat density and leaf area index LAI (estimated using a hemispherical camera). From satellite data, a profile of the normalized difference vegetation index (NDVI) was generated for each pixel. For both types of cereal, a relationship is established between NDVI and leaf area index LAI. This relationship is exponential and it allows connecting the satellite observations with a variable

  4. Influence of second-phase particles on grain growth in AZ31 magnesium alloy during equal channel angular pressing by phase field simulation

    Science.gov (United States)

    He, Ri; Wang, Mingtao; Zhang, Xiangang; Yaping Zong, Bernie

    2016-06-01

    A phase-field model was established to simulate the refinement effect of different morphological factors of second-phase particles such as Al2O3 on the grain growth of AZ31 magnesium alloy during equal channel angular pressing (ECAP) in realistic spatiotemporal evolution. The simulation results agreed well with limited existing experimental data for the ECAP-processed AZ31 magnesium alloy and were consistent with the law of Zener. Simulations were performed to evaluate the influences of the fraction, size, distribution, and shape of incoherent second-phase particles. The simulation results showed that during high-temperature ECAP processes, the addition of 2 wt.% Al2O3 particles resulted in a strong refinement effect, reducing the grain size by 28.7% compared to that of the alloy without the particles. Nevertheless, when the fraction of particles was greater than 4 wt.%, adding more particles had little effect. In AZ31 Mg alloy, it was found that second-phase particles should have a critical size of 0.5-0.8 μm for the grain refinement effect to occur. If the size is smaller than the critical size, large particles will strongly hinder grain growth; in contrast, if the size is larger than the critical size, large particles will exhibit a weaker hindering effect than small particles. Moreover, the results showed that the refinement effect increased with increasing particle fraction located at grain boundaries with respect to the total particle content. However, the refinement effect was less pronounced when the fraction of particles located at boundaries was greater than 70%. Further simulations indicated that spherical second-phase particles hindered grain growth more than ellipsoid particles and much more than rod-shaped particles when the volume fraction of reinforcing particles was 2%. However, when the volume fraction was greater than 8%, rod-shaped particles best hindered grain growth, and spherical particles exhibited the weakest effect.

  5. Physicists and Economic Growth: Preparing the Next Generation

    Science.gov (United States)

    Arion, Douglas

    2012-02-01

    For many years it has been recognized that many physicists are ``hidden'' -- deep in the industrial world or holding positions not named ``physicist.'' In parallel with this phenomenon is the recognition that many new and innovative product ideas are, in fact, generated by physicists. There are many more ideas that could be brought to market to the benefit of both society and the inventor, but physicists don't often see themselves as the innovators and inventors that they actually are. A number of education programs have arisen to try to address this issue and to engender a greater entrepreneurial spirit in the scientific community. The ScienceWorks program at Carthage College was one of the first to do so, and has for nearly twenty years prepared undergraduate science majors to understand and practice innovation and value creation. Other programs, such as professional masters degrees, also serve to bridge the technical and business universes. As it is no doubt easier to teach a scientist the world of business than it is to teach a businessperson the world of physics, providing educational experiences in innovation and commercialization to physics students can have tremendous economic impact, and will also better prepare them for whatever career direction they may ultimately pursue, even if it is the traditional tenure-track university position. This talk will discuss education programs that have been effective at preparing physics students for the professional work environment, and some of the positive outcomes that have resulted. Also discussed will be the variety of opportunities and resources that exist for faculty and students to develop the skills, knowledge and abilities to recognize and successfully commercialize innovations.

  6. Plant Growth Promoting Bacteria from Cow Dung Based Biodynamic Preparations

    OpenAIRE

    Radha, T. K.; RAO, D. L. N.

    2014-01-01

    Indigenous formulations based on cow dung fermentation are commonly used in organic farming. Three biodynamic preparations viz., Panchagavya (PG), BD500 and ‘Cow pat pit’ (CPP) showed high counts of lactobacilli (109 ml−1) and yeasts (104 ml−1). Actinomycetes were present only in CPP (104 ml−1) and absent in the other two. Seven bacterial isolates from these ferments were identified by a polyphasic approach: Bacillus safensis (PG1), Bacillus cereus (PG2, PG4 PG5), Bacillus subtilis (BD2) Lysi...

  7. The influence of the recrystallization mechanisms and grain growth on the texture of a hot rolled AZ31 sheet during subsequent isochronal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Victoria-Hernandez, J., E-mail: jose.victoria-hernandez@hzg.de; Yi, S.; Bohlen, J.; Kurz, G.; Letzig, D.

    2014-12-15

    Highlights: • The rolling texture of a twin roll cast AZ31 shows broad off-basal orientations. • Prismatic and pyramidal slip, and secondary twins influence the rolling texture. • Discontinuous recrystallization is promoted in grains deformed by pyramidal slip. • Recovery and extended recovery are promoted in grains deformed by prismatic slip. • Fast growing grain with orientation close to (0 0 0 1) lead the formation of a basal texture. - Abstract: The texture development during isochronal annealing at 250, 300 and 350 °C for 30 min of a hot rolled Mg AZ31 sheet produced by twin-roll casting was studied in this work. It was found that the rolling texture shows some features that resemble the textures that develop in rolled Mg alloys with rare earth additions. During further heat treatment, special attention was given to the deformation and recrystallization mechanisms, and grain growth that control the texture development. It was found that at 250 and 300 °C extended recovery and discontinuous recrystallization influence the texture by generating strain free grains with off-basal orientation. Conversely, during annealing at 350 °C growth of grains with their c-axis close to the (0 0 0 1) leads to the formation of the well-known basal type texture.

  8. Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

    Directory of Open Access Journals (Sweden)

    Xuejun Dong

    2016-05-01

    Full Text Available High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm

  9. Sodium induced grain growth, defect passivation and enhancement in the photovoltaic properties of Cu{sub 2}ZnSnS{sub 4} thin film solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Om Pal; Gour, Kuldeep Singh [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Academy of Scientific and Innovative Research, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Parmar, Rahul [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Singh, Vidya Nand, E-mail: singhvn@nplindia.org [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Academy of Scientific and Innovative Research, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)

    2016-07-01

    Sodium diffusion from soda lime glass (SLG) during high temperature annealing is known to play a crucial role in affecting the grain growth and defect passivation in chalocogenide/kesterite solar cells. Additional sodium is required when low temperature or short term annealing is used. Although this fact is known, a systematic comparative study for kesterite films is seldom reported. In the present study, Cu{sub 2}ZnSnS{sub 4} thin films were deposited on SLG and Mo coated SLG using stacked layer reactive sputtering. Na was deposited over the CZTS thin film and the film was annealed in N{sub 2} atmosphere in order to enhance the grain growth. This resulted in the shift in the XRD peak towards lower diffraction angle. The optical bandgap shifted from 1.45 eV to 1.38 eV with Na addition. Significant grain growth from hundreds of nanometer to micrometer was observed in samples with Na. Device fabricated in SLG/Mo/CZTS/CdS/ZnO/ITO configuration with Al front contact shows increase in efficiencies values from 1.50% to 2.84%. - Highlights: • Reactive sputtering with reduced annealing time have been used for the growth of CZTS thin film. • NaF has been deposited over precursor film before annealing. • Na addition resulted in grain growth, improved compactness and reduction in band gap. • An enhancement in the photovoltaic characteristics have been observed with addition of Na.

  10. Polymer-Coated Urea Delays Growth and Accumulation of Key Nutrients in Aerobic Rice but Does Not Affect Grain Mineral Concentrations

    Directory of Open Access Journals (Sweden)

    Terry J. Rose

    2016-01-01

    Full Text Available Enhanced efficiency nitrogen (N fertilizers (EEFs may improve crop recovery of fertilizer-N, but there is evidence that some EEFs cause a lag in crop growth compared to growth with standard urea. Biomass and mineral nutrient accumulation was investigated in rice fertilized with urea, urea-3,4-dimethylpyrazole phosphate (DMPP and polymer-coated urea (PCU to determine whether any delays in biomass production alter the accumulation patterns, and subsequent grain concentrations, of key mineral nutrients. Plant growth and mineral accumulation and partitioning to grains did not differ significantly between plants fertilized with urea or urea-DMPP. In contrast, biomass accumulation and the accumulation of phosphorus, potassium, calcium, magnesium, copper, zinc and manganese were delayed during the early growth phase of plants fertilized with PCU. However, plants in the PCU treatment ultimately compensated for this by increasing growth and nutrient uptake during the latter vegetative stages so that no differences in biomass or nutrient accumulation generally existed among N fertilizer treatments at anthesis. Delayed biomass accumulation in rice fertilized with PCU does not appear to reduce the total accumulation of mineral nutrients, nor to have any impact on grain mineral nutrition when biomass and grain yields are equal to those of rice grown with urea or urea-DMPP.

  11. Burkholderia ambifaria and B. caribensis promote growth and increase yield in grain amaranth (Amaranthus cruentus and A. hypochondriacus) by improving plant nitrogen uptake.

    Science.gov (United States)

    Parra-Cota, Fannie I; Peña-Cabriales, Juan J; de Los Santos-Villalobos, Sergio; Martínez-Gallardo, Norma A; Délano-Frier, John P

    2014-01-01

    Grain amaranth is an emerging crop that produces seeds having high quality protein with balanced amino-acid content. However, production is restricted by agronomic limitations that result in yields that are lower than those normally produced by cereals. In this work, the use of five different rhizobacteria were explored as a strategy to promote growth and yields in Amaranthus hypochondriacus cv. Nutrisol and A. cruentus cv. Candil, two commercially important grain amaranth cultivars. The plants were grown in a rich substrate, high in organic matter, nitrogen (N), and phosphorus (P) and under greenhouse conditions. Burkholderia ambifaria Mex-5 and B. caribensis XV proved to be the most efficient strains and significantly promoted growth in both grain amaranth species tested. Increased grain yield and harvest index occurred in combination with chemical fertilization when tested in A. cruentus. Growth-promotion and improved yields correlated with increased N content in all tissues examined. Positive effects on growth also occurred in A. cruentus plants grown in a poor soil, even after N and P fertilization. No correlation between non-structural carbohydrate levels in roots of inoculated plants and growth promotion was observed. Conversely, gene expression assays performed at 3-, 5- and 7-weeks after seed inoculation in plants inoculated with B. caribensis XV identified a tissue-specific induction of several genes involved in photosynthesis, sugar- and N- metabolism and transport. It is concluded that strains of Burkholderia effectively promote growth and increase seed yields in grain amaranth. Growth promotion was particularly noticeable in plants grown in an infertile soil but also occurred in a well fertilized rich substrate. The positive effects observed may be attributed to a bio-fertilization effect that led to increased N levels in roots and shoots. The latter effect correlated with the differential induction of several genes involved in carbon and N metabolism

  12. Influence Of Fine-Grained Montmorillonite On Microfungal Pellets Growth In Aqueous Suspensions

    Directory of Open Access Journals (Sweden)

    Jesenák Karol

    2015-06-01

    Full Text Available The paper presents an inhibition effect of clay mineral – montmorillonite – on the growth of microscopic filamentous fungus Aspergillus niger in the aqueous solution. The significant reduction in growth of the final size of spherical fungal pellets as well as total amount of produced microbial biomass was found out. Within the observed range of additions of clay mineral of 1, 5, 10, 15 and 20 g in the total volume of the 80 ml suspension, this size was in indirect relation to the weight of montmorillonite. However, the most significant inhibition effect was observed at the lowest concentration of the sorbent (1 g. Microscopic analysis of pellets referred to the presence of mineral particles in their pore structure and the distribution of particles in the spatial structure of fungal hyphae was variable. The experiment clearly demonstrated an inhibition effect of montmorillonite. This inhibition could be answered by the experiments focused on the detection of the influence of size and shape of inorganic sorption particles together with the influence of the physicochemical properties of its surface. It could be stated that the simultaneous application of the microscopic fungus Aspergillus niger and the clay mineral montmorillonite for decontamination of waste waters should be disadvantage due to their interaction if compared with the decontamination based on bioaccumulation and sorption separately.

  13. CH3NH3PbI3 grain growth and interfacial properties in meso-structured perovskite solar cells fabricated by two-step deposition.

    Science.gov (United States)

    Yao, Zhibo; Wang, Wenli; Shen, Heping; Zhang, Ye; Luo, Qiang; Yin, Xuewen; Dai, Xuezeng; Li, Jianbao; Lin, Hong

    2017-01-01

    Although the two-step deposition (TSD) method is widely adopted for the high performance perovskite solar cells (PSCs), the CH3NH3PbI3 perovskite crystal growth mechanism during the TSD process and the photo-generated charge recombination dynamics in the mesoporous-TiO2 (mp-TiO2)/CH3NH3PbI3/hole transporting material (HTM) system remains unexploited. Herein, we modified the concentration of PbI2 (C(PbI2)) solution to control the perovskite crystal properties, and observed an abnormal CH3NH3PbI3 grain growth phenomenon atop mesoporous TiO2 film. To illustrate this abnormal grain growth mechanism, we propose that a grain ripening process is taking place during the transformation from PbI2 to CH3NH3PbI3, and discuss the PbI2 nuclei morphology, perovskite grain growing stage, as well as Pb:I atomic ratio difference among CH3NH3PbI3 grains with different morphology. These C(PbI2)-dependent perovskite morphologies resulted in varied charge carrier transfer properties throughout the mp-TiO2/CH3NH3PbI3/HTM hybrid, as illustrated by photoluminescence measurement. Furthermore, the effect of CH3NH3PbI3 morphology on light absorption and interfacial properties is investigated and correlated with the photovoltaic performance of PSCs.

  14. Nanoparticle-induced grain growth of carbon-free solution-processed CuIn(S,Se)2 solar cell with 6% efficiency.

    Science.gov (United States)

    Cai, Yongan; Ho, John C W; Batabyal, Sudip K; Liu, Wei; Sun, Yun; Mhaisalkar, Subodh G; Wong, Lydia H

    2013-03-13

    Chalcopyrite-based solar cell deposited by solution processes is of great research interest because of the ease of fabrication and cost effectiveness. Despite the initial promising results, most of the reported methods encounter challenges such as limited grain growth, carbon-rich interlayer, high thermal budget, and the presence of secondary Cu-rich phases, which limit the power conversion efficiency (PCE). In this paper, we develop a new technique to deposit large grain, carbon-free CISSe absorber layers from aqueous nanoparticle/precursor mixture which resulted in a solar cell with PCE of 6.2%. CuCl2, InCl3, and thiourea were mixed with CuS and In2S3 nanoparticles in water to form the unique nanoparticle/precursor solution. The Carbon layer formation was prevented because organic solvents were not used in the precursor. The copper-rich (CuS) nanoparticles were intentionally introduced as nucleation sites which accelerate grain growth. In the presence of nanoparticles, the grain size of CISSe film increased by a factor of 7 and the power conversion efficiency of the solar cell is 85% higher than the device without nanoparticle. This idea of using nanoparticles as a means to promote grain growth can be further exploited for other types of chalcopyrite thin film deposited by solution methods.

  15. Disk Sizes and Grain Growth across the Brown Dwarf Boundary from the Taurus Boundary of Stellar/Substellar (TBOSS) Survey

    Science.gov (United States)

    Patience, Jenny; Ward-Duong, Kimberly; Bulger, Joanna; van der Plas, Gerrit; Menard, Francois; Pinte, Christophe; Bryden, Geoffrey; Turner, Neal J.; Jackson, Alan Patrick; Harvey, Paul M.; Hales, Antonio

    2017-01-01

    With a combination of submm/mm observations from ALMA, CSO, and PdBI, we are investigating the properties of disks around low mass stars and brown dwarfs in the Taurus star-forming region. Disk sizes and spectral slopes are important properties to assess the formation scenarios for brown dwarfs and the viability of planet formation in the disks. The ALMA maps have a beam size of approximately 0.3arcseconds and a number of the sources are spatially resolved in the continuum and CO(3-2) line measurements. For most of the resolved systems, the gas disks are more extended than the dust disks, similar to previous results from observations of more massive stars. From the multi-wavelength data, we are measuring the spectral slope of the emission to search for the signature of initial grain growth that is encoded in the slope of the spectral energy distribution in order to test the hypothesis of enhanced radial drift in disks around substellarobjects. Theoretical studies have suggested that fast radial drift could prevent the growth of dust particles up to large bodies in brown dwarf disks, and our program is designed to obtain a set of measurements for objects across the stellar/substellar transition.

  16. Fine-grained Delaunay triangulation in a simulation of tumor spheroid growth

    CERN Document Server

    Fabbro, A D; Milotti, E; Chignola, Roberto; Fabbro, Alessio Del; Milotti, Edoardo

    2006-01-01

    The simulation of many-particle systems often requires the detailed knowledge of proximity relations to reduce computational complexity and to provide a basis for specific calculations. Here we describe the basic scheme of a simulator of tumor spheroid growth: the calculation of mechanical interactions between cells and of the concentrations of diffusing chemicals requires a backbone provided by the Delaunay triangulation and the volumes of the associated Voronoi regions. Thus the Delaunay triangulation provides both the proximity relations needed to reduce the computational complexity and the basic structures that are needed to carry out the calculation of the biochemical interactions between cells and with the enviroment. A 3D version of the simulator uses the CGAL library as an essential component for the efficient computation of the Delaunay triangulation and of the Voronoi regions.

  17. Different dust and gas radial extents in protoplanetary disks: consistent models of grain growth and CO emission

    Science.gov (United States)

    Facchini, S.; Birnstiel, T.; Bruderer, S.; van Dishoeck, E. F.

    2017-09-01

    Context. ALMA observations of protoplanetary disks confirm earlier indications that there is a clear difference between the dust and gas radial extents. The origin of this difference is still debated, with both radial drift of the dust and optical depth effects suggested in the literature. Aims: In thermo-chemical models, the dust properties are usually prescribed by simple parametrisations. In this work, the feedback of more realistic dust particle distributions onto the gas chemistry and molecular emissivity is investigated, with a particular focus on CO isotopologues. Methods: The radial dust grain size distribution is determined using dust evolution models that include growth, fragmentation, and radial drift for a given static gas density structure. The vertical settling of dust particles is computed in steady-state. A new version of the code DALI is used to take into account how dust surface area and density influence the disk thermal structure, molecular abundances, and excitation. Synthetic images of both continuum thermal emission and low J CO isotopologues lines are produced. Results: The difference of dust and gas radial sizes is largely due to differences in the optical depth of CO lines and millimeter continuum, without the need to invoke radial drift. The effect of radial drift is primarily visible in the sharp outer edge of the continuum intensity profile. The gas outer radius probed by 12CO emission can easily differ by a factor of two between the models for a turbulent α ranging between 10-4 and 10-2, with the ratio of the CO and mm radius RoutCO/Routmm increasing with turbulence. Grain growth and settling concur in thermally decoupling the gas and dust components, due to the low collision rate with large grains. As a result, the gas can be much colder than the dust at intermediate heights, reducing the CO excitation and emission, especially for low turbulence values. Also, due to disk mid-plane shadowing, a second CO thermal desorption (rather

  18. Controlled Crystal Grain Growth in Mixed Cation-Halide Perovskite by Evaporated Solvent Vapor Recycling Method for High Efficiency Solar Cells.

    Science.gov (United States)

    Numata, Youhei; Kogo, Atsushi; Udagawa, Yosuke; Kunugita, Hideyuki; Ema, Kazuhiro; Sanehira, Yoshitaka; Miyasaka, Tsutomu

    2017-06-07

    We developed a new and simple solvent vapor-assisted thermal annealing (VA) procedure which can reduce grain boundaries in a perovskite film for fabricating highly efficient perovskite solar cells (PSCs). By recycling of solvent molecules evaporated from an as-prepared perovskite film as a VA vapor source, named the pot-roast VA (PR-VA) method, finely controlled and reproducible device fabrication was achieved for formamidinium (FA) and methylammonium (MA) mixed cation-halide perovskite (FAPbI3)0.85(MAPbBr3)0.15. The mixed perovskite was crystallized on a low-temperature prepared brookite TiO2 mesoporous scaffold. When exposed to very dilute solvent vapor, small grains in the perovskite film gradually unified into large grains, resulting in grain boundaries which were highly reduced and improvement of photovoltaic performance in PSC. PR-VA-treated large grain perovskite absorbers exhibited stable photocurrent-voltage performance with high fill factor and suppressed hysteresis, achieving the best conversion efficiency of 18.5% for a 5 × 5 mm(2) device and 15.2% for a 1.0 × 1.0 cm(2) device.

  19. Antagonistic activity of Ocimum sanctum L. essential oil on growth and zearalenone production by Fusarium graminearum in maize grains

    Directory of Open Access Journals (Sweden)

    Naveen Kumar eKalagatur

    2015-09-01

    Full Text Available The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO on growth and zearalenone (ZEA production of Fusarium graminearum. GC-MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%. DPPH free radical scavenging activity (IC50 of OSEO was determined to be 8.5µg/mL. Minimum inhibitory concentration (MIC and minimum fungicidal concentration (MFC of OSEO on F. graminearum were recorded as 1250 µg/mL and 1800 µg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 µg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 µg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13 revealed that increase in OSEO concentration (250 µg/mL to 1500 µg/mL significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers.

  20. Antagonistic activity of Ocimum sanctum L. essential oil on growth and zearalenone production by Fusarium graminearum in maize grains.

    Science.gov (United States)

    Kalagatur, Naveen K; Mudili, Venkataramana; Siddaiah, Chandranayaka; Gupta, Vijai K; Natarajan, Gopalan; Sreepathi, Murali H; Vardhan, Batra H; Putcha, Venkata L R

    2015-01-01

    The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO) on growth and zearalenone (ZEA) production of Fusarium graminearum. GC-MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%). DPPH free radical scavenging activity (IC50) of OSEO was determined to be 8.5 μg/mL. Minimum inhibitory concentration and minimum fungicidal concentration of OSEO on F. graminearum were recorded as 1250 and 1800 μg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 μg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 μg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13) revealed that increase in OSEO concentration (250-1500 μg/mL) significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers.

  1. Epitaxial Growth of Large-Grain NiSe Films by Solid-State Reaction for High-Responsivity Photodetector Arrays.

    Science.gov (United States)

    Cai, Caoyuan; Ma, Yang; Jeon, Jaeho; Huang, Fan; Jia, Feixiang; Lai, Shen; Xu, Zhihao; Wu, Congjun; Zhao, Ruiqi; Hao, Yufeng; Chen, Yiqing; Lee, Sungjoo; Wang, Min

    2017-05-01

    Film-based photodetectors have shown superiority for the fabrication of photodetector arrays, which are desired for integrating photodetectors into sensing and imaging systems, such as image sensors. But they usually possess a low responsivity due to low carrier mobility of the film consisting of nanocrystals. Large-grain semiconductor films are expected to fabricate superior-responsivity photodetector arrays. However, the growth of large-grain semiconductor films, normally with a nonlayer structure, is still challenging. Herein, this study introduces a solid-state reaction method, in which the growth rate is supposed to be limited by diffusion and reaction rate, for interface-confined epitaxial growth of nonlayer structured NiSe films with grain size up to micrometer scale on Ni foil. Meanwhile, patterned growth of NiSe films allows the fabrication of NiSe film based photodetector arrays. More importantly, the fabricated photodetector based on as-grown high-quality NiSe films shows a responsivity of 150 A W(-1) in contrast to the value of 0.009 A W(-1) from the photodetector based on as-deposited NiSe film consisting of nanocrystals, indicating a huge responsivity-enhancement up to four orders of magnitude. It is ascribed to the enhanced charge carrier mobility in as-grown NiSe films by dramatically decreasing the amount of grain boundary leading to scattering of charge carrier. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Growth performance and total tract nutrient digestion for Holstein heifers limit-fed diets high in distillers grains with different forage particle size

    Science.gov (United States)

    This study evaluated dairy heifer growth performance and total tract nutrient digestion when fed diets high in dried distillers grains with solubles (DDGS) with different forage particle size. An 8-wk randomized complete block design study was conducted utilizing twenty-two Holstein heifers (123 ±...

  3. A review of triticale uses and the effect of growth environment on grain quality.

    Science.gov (United States)

    McGoverin, Cushla M; Snyders, Franci; Muller, Nina; Botes, Willem; Fox, Glen; Manley, Marena

    2011-05-01

    Triticale (× Triticosecale sp. Wittmack ex A. Camus 1927) is an anthropogenic cereal designed to incorporate the functionality and high yield of wheat (Triticum spp. Linnaeus 1753) and durability of rye (Secale cereale Linnaeus 1753). The potential of triticale has remained largely unrealised, and in the 135 years since A. Stephen Wilson first crossed wheat and rye, triticale has mostly been used as animal feed. Growing demand for food resources has led to an increased interest in triticale development. Efforts to breed cultivars appropriate for baking have met with difficulty, although relatively new approaches to triticale end-use propose greater applicability for human consumption. Further, environmental awareness has generated interest in the use of triticale within biofuel production. We review environmental and genetic effects on triticale yield with a view towards increased demand on a hardy and useful cereal crop. We find triticale could satisfy many of the hopes originally placed upon it, and may be useful in foodstuffs and fuel, but only when growth environment is carefully considered.

  4. Coarse-grained molecular simulation of epidermal growth factor receptor protein tyrosine kinase multi-site self-phosphorylation.

    Directory of Open Access Journals (Sweden)

    John G Koland

    2014-01-01

    Full Text Available Upon the ligand-dependent dimerization of the epidermal growth factor receptor (EGFR, the intrinsic protein tyrosine kinase (PTK activity of one receptor monomer is activated, and the dimeric receptor undergoes self-phosphorylation at any of eight candidate phosphorylation sites (P-sites in either of the two C-terminal (CT domains. While the structures of the extracellular ligand binding and intracellular PTK domains are known, that of the ∼225-amino acid CT domain is not, presumably because it is disordered. Receptor phosphorylation on CT domain P-sites is critical in signaling because of the binding of specific signaling effector molecules to individual phosphorylated P-sites. To investigate how the combination of conventional substrate recognition and the unique topological factors involved in the CT domain self-phosphorylation reaction lead to selectivity in P-site phosphorylation, we performed coarse-grained molecular simulations of the P-site/catalytic site binding reactions that precede EGFR self-phosphorylation events. Our results indicate that self-phosphorylation of the dimeric EGFR, although generally believed to occur in trans, may well occur with a similar efficiency in cis, with the P-sites of both receptor monomers being phosphorylated to a similar extent. An exception was the case of the most kinase-proximal P-site-992, the catalytic site binding of which occurred exclusively in cis via an intramolecular reaction. We discovered that the in cis interaction of P-site-992 with the catalytic site was facilitated by a cleft between the N-terminal and C-terminal lobes of the PTK domain that allows the short CT domain sequence tethering P-site-992 to the PTK core to reach the catalytic site. Our work provides several new mechanistic insights into the EGFR self-phosphorylation reaction, and demonstrates the potential of coarse-grained molecular simulation approaches for investigating the complexities of self-phosphorylation in

  5. Effect of Material and Process Atmosphere in the Preparation of Al-Ti-B Grain Refiner by SHS

    Directory of Open Access Journals (Sweden)

    Iban Vicario

    2015-07-01

    Full Text Available Al-Ti-B master alloys are widely used in the aluminum industry as grain refiners for the control of the microstructure of the aluminum alloys. The SHS (self-propagating high-temperature synthesis is an ex situ method that uses exothermic reactions to sustain the chemical reaction in a combustion wave. The advantages of SHS are the low energy requirement, simplicity and product purity. However, the raw material used has to be very pure, with a very small size leading to the necessity of a reactor with a protective gas to produce the reaction. The purpose of this investigation is to fabricate SHS master alloys with commercial standard raw materials, with lower purity and higher grain size without a reactor or protective gas in order to (1 decrease the price and (2 improve the productivity of master alloy manufacturing. The possibility of using cheap borated salts instead of expensive pure boron has been studied. Different compositions of aluminum master alloy have been developed. Bigger TiB2 grain size has been obtained when using bigger commercial raw materials. Larger titanium powder can produce an aluminum master alloy with a maximum of 30% of aluminum without reactor. In comparison, SHS reaction is much more difficult when using finer titanium powder.

  6. The effect of heat treatment and thermal spray processes on the grain growth of nanostructured composite CoNiCrAlY/YSZ powders

    Energy Technology Data Exchange (ETDEWEB)

    Tahari, Mostafa, E-mail: fa.tahari@yahoo.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Department of Engineering, Esfarayen University of Technology, Esfarayen-North Khorasan 96619-98195 (Iran, Islamic Republic of); Shamanian, Morteza; Salehi, Mehdi [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2015-10-15

    This research investigated thermal stability of mechanically milled MCrAlY/YSZ composites during heat treatment and high velocity oxy-fuel (HVOF) thermal spray processes. MCrAlY powder was mixed with 5%, 10% and 15% YSZ and then milled for 12 and 24 h. A powder without YSZ reinforcement ball was milled for 12 and 24 h too. The composite powders were annealed for 10 h at 1273 K to investigate thermal stability. Nanocrystalline and commercial powders were deposited on Inconel-617 substrate using the HVOF process. The morphology and thermal stability of mechanically milled and heat treated powders and coatings were investigated using X-ray diffractometry, scanning electron microscopy (SEM) and optical microscopy (OM). It was found that the increase in milling time resulted in the uniform distribution of reinforcements in the γ phase matrix. The uniform distribution of reinforcements caused reduction in grain growth during heat treatment process. On the other hand, increasing YSZ percentage decreased grain growth, but when the YSZ amount exceeded 10%, the ceramic reinforcements could not prevent the grain growth of nanostructure powders. The heat absorbed by nanostructured powders during thermal spraying process resulted in the grain growth of the γ-phase, but due to the presence of YSZ reinforcement, the grain growth was very lower than that of unreinforced coatings. It could be suggested that nanostructure coating formed due to thermo mechanical phenomena occurred in commercial powder particles during thermal spray process. - Highlights: • CoNiCrAlY/YSZ composite. • Nanostructure powder. • Heat treatment of CoNiCrAlY/YSZ.

  7. Dust properties and disk structure of evolved protoplanetary disks in Cep OB2: Grain growth, settling, gas and dust mass, and inside-out evolution

    CERN Document Server

    Sicilia-Aguilar, Aurora; Dullemond, Cornelis P; Patel, Nimesh; Juhász, Attila; Bouwman, Jeroen; Sturm, Bernhard

    2011-01-01

    We present Spitzer/IRS spectra of 31 TTS and IRAM/1.3mm observations for 34 low- and intermediate-mass stars in the Cep OB2 region. Including our previously published data, we analyze 56 TTS and the 3 intermediate-mass stars with silicate features in Tr 37 (~4 Myr) and NGC 7160 (~12 Myr). The silicate emission features are well reproduced with a mixture of amorphous (with olivine, forsterite, and silica stoichiometry) and crystalline grains (forsterite, enstatite). We explore grain size and disk structure using radiative transfer disk models, finding that most objects have suffered substantial evolution (grain growth, settling). About half of the disks show inside-out evolution, with either dust-cleared inner holes or a radially-dependent dust distribution, typically with larger grains and more settling in the innermost disk. The typical strong silicate features require nevertheless the presence of small dust grains, and could be explained by differential settling according to grain size, anomalous dust distr...

  8. Densification and grain growth during sintering of porous Ce0.9Gd0.1O1.95tape cast layers: A comprehensive study on heuristic methods

    DEFF Research Database (Denmark)

    Ni, De Wei; Schmidt, Cristine Grings; Teocoli, Francesca

    2013-01-01

    the dominant sintering mechanisms and kinetics, both in isothermal and at constant heating rate (iso-rate) conditions. Densification of porous CGO10 tape is thermally activated with typical activation energy which was estimated around 440–470 kJ mol−1. Grain growth showed similar thermal activation energy...... of ∼427 ± 22 kJ mol−1in the temperature range of 1100–1250ºC. Grain-boundary diffusion was identified to be the dominant mechanism in porous CGO10 tapes. Grain growth and densification mechanism were found strictly related in the investigated temperature range. Porosity acts as a grain growth inhibitor...

  9. Whole-plant dynamic system of nitrogen use for vegetative growth and grain filling in rice plants (Oryza sativa L. as revealed through the production of 350 grains from a germinated seed over 150 days: a review and synthesis

    Directory of Open Access Journals (Sweden)

    Tadakatsu Yoneyama

    2016-08-01

    Full Text Available A single germinated rice (Oryza sativa L seed can produce 350 grains with the sequential development of 15 leaves on the main stem and 7 ‒ 10 leaves on 4 productive tillers (forming 5 panicles in total, using nitrogen (N taken up from the environment over a 150-day growing season. Nitrogen travels from uptake sites to the grain through growing organ-directed cycling among sequentially developed organs. Over the past 40 years, the dynamic system for N allocation during vegetative growth and grain filling has been elucidated through studies on N and 15N transport as well as enzymes and transporters involved. In this review, we synthesize the information obtained in these studies along the following main points: (1 During vegetative growth before grain-filling, about half of the total N in the growing organs, including young leaves, tillers, root tips and differentiating panicles is supplied via phloem from mature source organs such as leaves and roots, after turnover and remobilization of proteins, whereas the other half is newly taken up and supplied via xylem, with an efficient xylem-to-phloem transfer at stem nodes. Thus, the growth of new organs depends equally on both N sources. (2 A large fraction (as much as 80% of the grain N is derived largely from mature organs such as leaves and stems by degradation, including the autophagy pathway of chloroplast proteins (e.g., Rubisco. (3 Mobilized proteinogenic amino acids, including arginine, lysine, proline and valine, are derived mainly from protein degradation, with amino acid transporters playing a role in transferring these amino acids across cell membranes of source and sink organs, and enabling their efficient reutilization in the latter. On the other hand, amino acids such as glutamine, glutamic acid, γ-amino butyric acid, aspartic acid, and alanine are produced by assimilation of newly taken up N by roots and transported via xylem and phloem. The formation of 350 filled grains over 50

  10. Whole-Plant Dynamic System of Nitrogen Use for Vegetative Growth and Grain Filling in Rice Plants (Oryza sativa L.) as Revealed through the Production of 350 Grains from a Germinated Seed Over 150 Days: A Review and Synthesis.

    Science.gov (United States)

    Yoneyama, Tadakatsu; Tanno, Fumio; Tatsumi, Jiro; Mae, Tadahiko

    2016-01-01

    A single germinated rice (Oryza sativa L) seed can produce 350 grains with the sequential development of 15 leaves on the main stem and 7-10 leaves on four productive tillers (forming five panicles in total), using nitrogen (N) taken up from the environment over a 150-day growing season. Nitrogen travels from uptake sites to the grain through growing organ-directed cycling among sequentially developed organs. Over the past 40 years, the dynamic system for N allocation during vegetative growth and grain filling has been elucidated through studies on N and (15)N transport as well as enzymes and transporters involved. In this review, we synthesize the information obtained in these studies along the following main points: (1) During vegetative growth before grain-filling, about half of the total N in the growing organs, including young leaves, tillers, root tips and differentiating panicles is supplied via phloem from mature source organs such as leaves and roots, after turnover and remobilization of proteins, whereas the other half is newly taken up and supplied via xylem, with an efficient xylem-to-phloem transfer at stem nodes. Thus, the growth of new organs depends equally on both N sources. (2) A large fraction (as much as 80%) of the grain N is derived largely from mature organs such as leaves and stems by degradation, including the autophagy pathway of chloroplast proteins (e.g., Rubisco). (3) Mobilized proteinogenic amino acids (AA), including arginine, lysine, proline and valine, are derived mainly from protein degradation, with AA transporters playing a role in transferring these AAs across cell membranes of source and sink organs, and enabling their efficient reutilization in the latter. On the other hand, AAs such as glutamine, glutamic acid, γ-amino butyric acid, aspartic acid, and alanine are produced by assimilation of newly taken up N by roots and and transported via xylem and phloem. The formation of 350 filled grains over 50 days during the

  11. A novel, two-step top seeded infiltration and growth process for the fabrication of single grain, bulk (RE)BCO superconductors

    Science.gov (United States)

    Namburi, Devendra K.; Shi, Yunhua; Palmer, Kysen G.; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

    2016-09-01

    A fundamental requirement of the fabrication of high performing, (RE)-Ba-Cu-O bulk superconductors is achieving a single grain microstructure that exhibits good flux pinning properties. The top seeded melt growth (TSMG) process is a well-established technique for the fabrication of single grain (RE)BCO bulk samples and is now applied routinely by a number of research groups around the world. The introduction of a buffer layer to the TSMG process has been demonstrated recently to improve significantly the general reliability of the process. However, a number of growth-related defects, such as porosity and the formation of micro-cracks, remain inherent to the TSMG process, and are proving difficult to eliminate by varying the melt process parameters. The seeded infiltration and growth (SIG) process has been shown to yield single grain samples that exhibit significantly improved microstructures compared to the TSMG technique. Unfortunately, however, SIG leads to other processing challenges, such as the reliability of fabrication, optimisation of RE2BaCuO5 (RE-211) inclusions (size and content) in the sample microstructure, practical oxygenation of as processed samples and, hence, optimisation of the superconducting properties of the bulk single grain. In the present paper, we report the development of a near-net shaping technique based on a novel two-step, buffer-aided top seeded infiltration and growth (BA-TSIG) process, which has been demonstrated to improve greatly the reliability of the single grain growth process and has been used to fabricate successfully bulk, single grain (RE)BCO superconductors with improved microstructures and superconducting properties. A trapped field of ˜0.84 T and a zero field current density of 60 kA cm-2 have been measured at 77 K in a bulk, YBCO single grain sample of diameter 25 mm processed by this two-step BA-TSIG technique. To the best of our knowledge, this value of trapped field is the highest value ever reported for a sample

  12. Large Perovskite Grain Growth in Low-Temperature Solution-Processed Planar p-i-n Solar Cells by Sodium Addition.

    Science.gov (United States)

    Bag, Santanu; Durstock, Michael F

    2016-03-02

    Thin-film p-i-n type planar heterojunction perovskite solar cells have the advantage of full low temperature solution processability and can, therefore, be adopted in roll-to-roll production and flexible devices. One of the main challenges with these devices, however, is the ability to finely control the film morphology during the deposition and crystallization of the perovskite layer. Processes suitable for optimization of the perovskite layer film morphology with large grains are highly desirable for reduced recombination of charge carriers. Here, we show how uniform thin films with micron size perovskite grains can be made through the use of a controlled amount of sodium ions in the precursor solution. Large micrometer-size CH3NH3PbI3 perovskite grains are formed during low-temperature thin-film growth by adding sodium ions to the PbI2 precursor solution in a two-step interdiffusion process. By adjusting additive concentration, film morphologies were optimized and the fabricated p-i-n planar perovskite-PCBM solar cells showed improved power conversion efficiences (an average of 3-4% absolute efficiency enhancement) compared to the nonsodium based devices. Overall, the additive enhanced grain growth process helped to reach a high 14.2% solar cell device efficiency with low hysteresis. This method of grain growth is quite general and provides a facile way to fabricate large-grained CH3NH3PbI3 on any arbitrary surface by an all solution-processed route.

  13. Smoke in the Pipe Nebula: dust emission and grain growth in the starless core FeSt 1-457

    CERN Document Server

    Forbrich, Jan; Lombardi, Marco; Roman-Zuñiga, Carlos; Alves, João

    2015-01-01

    (abridged) Methods: We derive maps of submillimeter dust optical depth and effective dust temperature from Herschel data that were calibrated against Planck. After calibration, we then fit a modified blackbody to the long-wavelength Herschel data, using the Planck-derived dust opacity spectral index beta, derived on scales of 30' (or ~1 pc). We use this model to make predictions of the submillimeter flux density at 850 micron, and we compare these in turn with APEX-Laboca observations. Results: A comparison of the submillimeter dust optical depth and near-infrared extinction data reveals evidence for an increased submillimeter dust opacity at high column densities, interpreted as an indication of grain growth in the inner parts of the core. Additionally, a comparison of the Herschel dust model and the Laboca data reveals that the frequency dependence of the submillimeter opacity, described by the spectral index beta, does not change. A single beta that is only slightly different from the Planck-derived value ...

  14. A Study on the Thermodynamics of Grain Growth in R.F. Magnetron Sputtered NiO Thin Films

    Directory of Open Access Journals (Sweden)

    I. Dhanya

    2013-01-01

    Full Text Available Postdeposition annealing of thin nickel films synthesized using R.F. magnetron sputtering technique is carried in this study. The XRD analysis indicates that annealing of the nickel films leads to the formation of nickel oxide with a preferential growth along (200 plane. The oxidation mechanism is observed with a phase transformation and results in polycrystalline NiO films. The surface morphology of the thin films was investigated by scanning electron microscopy (SEM and atomic force microscopy (AFM as a function of annealing temperature. The studies indicate the formation of well-defined grain boundaries due to agglomeration of nanocrystallites. The films annealed in the range 573–773 K are found to be porous. The optical transmission spectra of the films annealed at 773 K exhibit interference effects for photon energies below the fundamental absorption edge. The optical studies indicate the existence of direct interband transition across a bandgap of 3.7 eV in confirmation with earlier band structure calculations.

  15. Sugarcane Aphid Population Growth, Plant Injury, and Natural Enemies on Selected Grain Sorghum Hybrids in Texas and Louisiana.

    Science.gov (United States)

    Brewer, Michael J; Gordy, John W; Kerns, David L; Woolley, James B; Rooney, William L; Bowling, Robert D

    2017-09-06

    In response to the 2013 outbreak of sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), on sorghum, Sorghum bicolor (L.), in North America, experiments were conducted at three southern U.S. grain sorghum production locations (Corpus Christi, TX; Winnsboro, LA; Rosenberg, TX). The objectives were to authenticate yield decline on susceptible hybrids (2014 and 2015) and to measure aphid population growth and natural enemy prevalence on susceptible and resistant hybrids with similar genetic background (2014). Yield decline on susceptible hybrids (Tx 2752/Tx430 and DKS53-67) was more substantial when aphid population growth accelerated quickly and peaked above 300 aphids per leaf (50 to nearly 100% yield decline). Location and year variation in maximum aphid density and cumulative aphid-days was high, with doubling time values on the susceptible hybrids ranging between 3.9 and 7.9 d. On resistant Tx2752/Tx2783, leaf injury and yield decline were not seen or less severe than on its paired susceptible Tx2752/Tx430. Aphids declined on Tx2752/Tx2783 after initial colony establishment (Corpus Christi) or took about 60% longer to double in population size when compared with Tx2572/Tx430 (Winnsboro). The predominant natural enemy taxa were aphelinid mummies (Hymenoptera: Aphelinidae), ladybird beetles (Coleoptera: Coccinellidae), and sryphid flies (Diptera: Syrphidae), and they were more prevalent during flowering than prior to flowering. They were generally responsive to changes in aphid density of both susceptible and resistant hybrids, but variability points to need for further study. In future research, full season observations should continue as well as more detailed study of potential compatibility of sorghum resistance and biological control. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. [Effects of nitrogen fertilization and root separation on the plant growth and grain yield of maize and its rhizosphere microorganisms].

    Science.gov (United States)

    Zhang, Xiang-Qian; Huang, Guo-Qin; Bian, Xin-Min; Zhao, Qi-Guo

    2012-12-01

    A field experiment with root separation was conducted to study the effects of root interaction in maize-soybean intercropping system on the plant growth and grain yield of maize and its rhizosphere microorganisms under different nitrogen fertilization levels (0.1, 0.3, 0.5, and 0.7 g x kg(-1)). Root interaction and nitrogen fertilization had positive effects on the plant height, leaf length and width, and leaf chlorophyll content of maize. Less difference was observed in the root dry mass of maize at maturing stage between the treatments root separation and no root separation. However, as compared with root separation, no root separation under the nitrogen fertilization levels 0.1, 0.3, 0.5, and 0.7 g x kg(-1) increased the biomass per maize plant by 8.8%, 6.3%, 3.6%, and 0.7%, and the economic yield per maize plant by 17.7%, 10.0%, 8.2%, and 0.9%, respectively. No root separation increased the quantity of rhizosphere fungi and azotobacteria significantly, as compared with root separation. With increasing nitrogen fertilization level, the quantity of rhizosphere bacteria, fungi, and actinomycetes presented an increasing trend, while that of rhizosphere azotobacteria decreased after an initial increase. The root-shoot ratio of maize at maturing stage was significantly negatively correlated with the quantity of rhizosphere bacteria, fungi, and actinomycetes, but less correlated with the quantity of rhizosphere azotobacteria. It was suggested that the root interaction in maize-soybean intercropping system could improve the plant growth of maize and increase the maize yield and rhizosphere microbial quantity, but the effect would be decreased with increasing nitrogen fertilization level.

  17. The growth units and hydrothermal preparation of lead tungstate (PbWO4) crystallites

    Institute of Scientific and Technical Information of China (English)

    元如林; 施尔畏; 李汶军; 郑燕青; 吴南春; 仲维卓

    2000-01-01

    The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2+). According to the growth unit model, the growth units of lead tungstate are the aggregations of the tungsten oxide tetrahedrons and lead cations with various geometry configurations. It is suggested that the favorable growth units of lead tungstate crystal are pyramidal, tetragonal prism and quadrangular units corresponding to geometric orientations of the simple forms of the crystal. Under low restricted growth conditions, the growth form of lead tungstate crystallites is the aggregation of the geometric configurations of these favorable growth units. The above conclusions are completely confirmed by the experiment on hydrothermal preparation of lead tungstate crystallites.

  18. The growth units and hydrothermal preparation of lead tungstate (PbWO4) crystallites

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2+). According to the growth unit model, the growth units of lead tungstate are the aggregations of the tungsten oxide tetrahedrons and lead cations with various geometry configurations. It is suggested that the favorable growth units of lead tungstate crystal are pyramidal, tetragonal prism and quadrangular units corresponding to geometric orientations of the simple forms of the crystal. Under low restricted growth conditions, the growth form of lead tungstate crystallites is the aggregation of the geometric configurations of these favorable growth units. The above conclusions are completely confirmed by the experiment on hydrothermal preparation of lead tungstate crystallites.

  19. A new seeding technique for the reliable fabrication of large, SmBCO single grains containing silver using top seeded melt growth

    Science.gov (United States)

    Shi, Y.-H.; Dennis, A. R.; Cardwell, D. A.

    2015-03-01

    Silver (Ag) is an established additive for improving the mechanical properties of single grain, (RE)Ba2Cu3O7-δ [(RE)BCO, RE = Sm, Gd and Y] bulk superconductors. The presence of Ag in the (RE)BCO bulk composition, however, typically reduces the melting temperature of the single crystal seed in the top seeded melt growth (TSMG) process, which complicates significantly the controlled nucleation and subsequent epitaxial growth of a single grain, which is essential for high field engineering applications. The reduced reliability of the seeding process in the presence of Ag is particularly acute for the SmBCO system, since the melting temperature of SmBCO is very close to that of the generic NdBCO(MgO) seed. SmBCO has a high superconducting transition temperature, Tc, and exhibits the most pronounced ‘peak’ effect at higher magnetic field of all materials in the family of (RE)BCO bulk superconductors and, therefore, has the greatest potential for use in practical applications (compared to GdBCO and YBCO, in particular). Development of an effective seeding process, therefore, is one of the major challenges of the TSMG process for the growth of large, high quantity single grain superconductors. In this paper, we report a novel technique that involves introducing a buffer layer between the seed crystal and the precursor pellet, primarily to inhibit the diffusion of Ag from the green body to the seed during melt processing in order to prevent the melting of the seed. The success rate of the seeding process using this technique is 100% for relatively small batches of samples. The superconducting properties, critical temperature, Tc, critical current density, Jc and trapped fields, of the single grains fabricated using the buffers are reported and the microstructures in the vicinity of the buffer of single grains fabricated by the modified technique are analysed to understand further the effects of buffers on the growth process of these technologically important

  20. Preparation of grain size controlled boron-doped diamond thin films and their applications in selective detection of glucose in basic solutions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Boron-doped diamond (BDD) thin films with different crystal grain sizes were prepared by controlling the reacting gas pressure using hot filament chemical vapor deposition (HFCVD).The morphologies and structures of the prepared diamond thin films were characterized by scanning electron microscopy (SEM) and Raman spectroscopy.The electrochemical responses of K4Fe(CN)6 on different BDD electrodes were investigated.The results suggested that electron transfer was faster at the boron-doped nanocrystalline diamond (BDND) thin film electrodes in comparison with that at other BDD thin film electrodes.The prepared BDD thin film electrodes without any modification were used to directly detect glucose in the basic solution.The results showed that the as-prepared BDD thin film electrodes exhibited good selectivity for detecting glucose in the presence of ascorbic acid (AA) and uric acid (UA).The higher sensitivity was observed on the BDND thin film grown on the boron-doped microcrystalline diamond (BDMD) thin film surface,and the linear response range,sensitivity and the low detection limit were 0.25–10 mM,189.1 μA mmol-1 cm-2 and 25 μM (S/N=3) for glucose in the presence of AA and UA,respectively.

  1. Rice growth improvement and grains bio-fortification through lime and zinc application in zinc deficit tropical acid sulphate soils

    Directory of Open Access Journals (Sweden)

    Shahram Mahmoud Soltani

    2016-10-01

    Full Text Available A two years field study was conducted to explain the effect of Zn and lime application on morphological characteristics, rice yield and yield components, and more broadly, grains bio-fortification (Zn and protein content (CP, and amino acid profiles. The lime and Zn interaction increased grains and straw yield more than two times (6.64 ton ha−1 compared to the control (3.20 ton ha−1. The maximum increase in the Zn content of grain, white rice and bran was obtained about 30% in whole grain, 42% in bran and 56% in white rice. Furthermore, CP increased by about 8% in bran, 12.3% in whole grain, and 27% in white rice compared to control. Also, the Zn and lime application and their interaction were significantly increased the amino acids, especially essential parts.

  2. Micrometer size grains of hot isostatically pressed alumina and its characterization

    Indian Academy of Sciences (India)

    A K Mallik; S Gangadharan; S Dutta; D Basu

    2010-08-01

    Alumina samples were prepared from two different particle size powders. Finer particle compacts when heated along with coarser particle compacts at same processing temperatures produce bigger grain microstructures due to higher grain growth. An unconventional method of etching by molten V2O5 was adopted to look at the microstructure for accuracy in reported data. On an average starting with finer particles give microstructure with a grain size of 5.5 m and starting with coarser particles, give microstructure with 2.2 m average grain size. The flexural strength is around 400 MPa for alumina samples prepared from finer powder in comparison with about 550 MPa for alumina samples prepared from coarser powder. The Vickers hardness in 5.5 m grain microstructure is around 20 GPa in comparison to about 18 GPa in microstructure with smaller grains of 2.2 m size.

  3. The effect of secondary abnormal grain growth on the dielectric properties of La/Mn co-doped BaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Živković Lj.M.

    2006-01-01

    Full Text Available La/Mn-codoped BaTiO3 systems, obtained by solid state reactions, were investigated regarding their microstructure characteristics and ferroelectric properties. Different concentrations of La2O3 were used for doping, ranging from 0.1 to 5.0 at% La, while a content of Mn was constant at 0.05 at%. For all samples sintered below the eutectic temperature (1332°C, a uniform microstructure was formed with average grain size from 1-3 μm. The appearance of secondary abnormal grains with (111 double twins grains with curved or faceted grain boundaries were observed in La/Mn BaTiO3 ceramics after sintering at temperatures above the eutectic temperature. All sintered samples exhibited a high electrical resistivity. Better dielectric performances were obtained for low doped samples (0.1 at% La sintered at 1350°C. For samples with La content above 1.0 at% a lower value in dielectric permittivity at higher sintering temperature is due to secondary abnormal grain growth, and to the presence of a non-ferroelectric phase rich in La. The Curie constant together with other dielectric parameters were also calculated.

  4. Preparation, characterization and combustion properties of Zr/ZrH2 particles coated with α-FeOOH crystal grains

    Institute of Scientific and Technical Information of China (English)

    Baoliang Lv; Yao Xu; Bo Hou; Dong Wu; Yuhan Sun

    2009-01-01

    Zr/ZrH2 particles with irregular morphologies and broad size distribution were uniformly coated with aci-cular α-FeOOH crystal grains via a facile route without using polymers or surfactants. The as-synthesized material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV-vis diffusion reflection (UV-vis) and Raman spectrometry. Based on these char-acterizations, the synthesis mechanism was explained in terms of combined heterogeneous nucleation and solid state transformation reaction. The presence of α-FeOOH coating greatly changed the combustion behavior of Zr/ZrH2 particles: the combustion lasting time decreased from 32 s for un-coated Zr/ZrH2 par-ticles to 0.2 s for coated particles while the maximum temperature in the combustion process increased from 1510℃ to 2036℃.

  5. Research on the growth orientation of pyrite grains in the colloform textures in Baiyunpu Pb-Zn polymetallic deposit, Hunan, China

    Science.gov (United States)

    Gao, Shang; Huang, Fei; Gu, Xiangping; Chen, Zhenyu; Xing, Miaomiao; Li, Yongli

    2017-02-01

    A large number of colloform-textured pyrites were found in Baiyunpu Pb-Zn ore bodies in Xinshao County, Hunan, China. This study investigates the growth orientation of the pyrite grains in these structures by field emission scanning electron microscopy (FE-SEM), in situ micro X-ray diffraction (μXRD) and electron backscatter diffraction (EBSD). The growth proceeded from micro-crystalline cores in the colloform textures. Moreover, the pyrite layers were discrete and separated by locally significant quantities of galena and calcite. The μXRD results suggested clear crystalline characteristics and weakly preferred orientations of the colloform textures. EBSD confirmed that the pyrite grains exist preferred orientations or in the layered zones. According to the crystal growth theory, the formation and variation of crystal preferred orientations (CPOs) in pyrite are mainly restricted by the internal crystal structure of the pyrite and depends on the external environment conditions, such as trace element concentrations and the supersaturation degree. We inferred the evolutionary regularity of lattice planes with different indices in the pyrite crystal structure from morphological, compositional and growth orientation information, which reflect the crystal growth history of the colloform pyrite. This study will advance our understanding of the growth processes of colloform pyrite and environmental evolution in the Baiyunpu Pb-Zn polymetallic deposits.

  6. Irradiation induced grain growth and surface emission enhancement of chemically tailored ZnS : Mn/PVOH nanoparticles by Cl+9 ion impact

    Indian Academy of Sciences (India)

    D Mohanta; S S Nath; N C Mishra; A Choudhury

    2003-04-01

    Manganese doped zinc sulfide nanoparticles are fabricated on polyvinyl alcohol dielectric matrix. They are bombarded with energetic chlorine ions (100 MeV). The size of the crystallites is found to increase with ion fluence due to melting led grain growth under ion irradiation. The increased size as a result of grain growth has been observed both in the optical absorption spectra in terms of redshift and in electron microscopic images. The photoluminescence (PL) study was carried out by band to band excitation ($\\lambda_{ex}$ = 220 nm) upon ZnS : Mn, which results into two emission peaks corresponding to surface states and Mn+2 emission, respectively. The ion fluence for irradiation experiment so chosen were 1 × 1011, 5 × 1011, 5 × 1012 and 1013 Cl/cm2.

  7. Effect of Preparation Parameter on Microstructure and Grain Refining Behavior of In Situ AlN-TiN-TiB2/Al Composite Inoculants on Pure Aluminum

    Directory of Open Access Journals (Sweden)

    Qian Wang

    2017-02-01

    Full Text Available The formation of in situ AlN-TiN-TiB2/Al composite inoculants, which contain multi-phase refiner particles including AlN, TiN, TiB2, Al3Ti, and α-Al, was investigated using nitrogen gas injection. The effects of the main preparation parameters such as nitriding temperature, nitriding time, Ti content in melts, on the microstructure and grain refinement of in situ AlN-TiN-TiB2/Al composite inoculants were studied. The shape, content and size of different ceramic particles in the inoculants can be tuned by controlling the nitriding temperature and time, inducing excellent refining and reinforcing effects on pure aluminum. As a result, the average grain size of pure aluminum can be reduced to about 122 ± 22 μm from original 1010 ± 80 μm by adding 0.3 wt % inoculants. The mechanical properties including the tensile strength, yield strength and microhardness of the refined as-cast pure aluminum are also improved.

  8. The Effect of Lithium Doping on the Sintering and Grain Growth of SPS-Processed, Non-Stoichiometric Magnesium Aluminate Spinel

    Directory of Open Access Journals (Sweden)

    Yuval Mordekovitz

    2016-06-01

    Full Text Available The effects of lithium doping on the sintering and grain growth of non-stoichiometric nano-sized magnesium aluminate spinel were studied using a spark plasma sintering (SPS apparatus. Li-doped nano-MgO·nAl2O3 spinel (n = 1.06 and 1.21 powders containing 0, 0.20, 0.50 or 1.00 at. % Li were synthesized by the solution combustion method and dense specimens were processed using a SPS apparatus at 1200 °C and under an applied pressure of 150 MPa. The SPS-processed samples showed mutual dependency on the lithium concentration and the alumina-to-magnesia ratio. For example, the density and hardness values of near-stoichiometry samples (n = 1.06 showed an incline up to 0.51 at. % Li, while in the alumina rich samples (n = 1.21, these values remained constant up to 0.53 at. % Li. Studying grain growth revealed that in the Li-MgO·nAl2O3 system, grain growth is limited by Zener pining. The activation energies of undoped, 0.2 and 0.53 at. % Li-MgO·1.21Al2O3 samples were 288 ± 40, 670 ± 45 and 543 ± 40 kJ·mol−1, respectively.

  9. A novel pre-sintering technique for the growth of Y-Ba-Cu-O superconducting single grains from raw metal oxides

    Science.gov (United States)

    Li, Jiawei; Shi, Yun-Hua; Dennis, Anthony R.; Namburi, Devendra Kumar; Durrell, John H.; Yang, Wanmin; Cardwell, David A.

    2017-09-01

    Most established top seeded melt growth (TSMG) processes of bulk, single grain Y-Ba-Cu-O (YBCO) superconductors are performed using a mixture of pre-reacted precursor powders. Here we report the successful growth of large, single grain YBCO samples by TSMG with good superconducting properties from a simple precursor composition consisting of a sintered mixture of the raw oxides. The elimination of the requirement to synthesize precursor powders in a separate process prior to melt processing has the potential to reduce significantly the cost of bulk superconductors, which is essential for their commercial exploitation. The growth morphology, microstructure, trapped magnetic field and critical current density, J c, at different positions within the sample and maximum levitation force of the YBCO single grains fabricated by this process are reported. Measurements of the superconducting properties show that the trapped filed can reach 0.45 T and that a zero field J c of 2.5 × 104 A cm-2 can be achieved in these samples. These values are comparable to those observed in samples fabricated using pre-reacted, high purity commercial oxide precursor powders. The experimental results are discussed and the possibility of further improving the melt process using raw oxides is outlined.

  10. Influence of preparation process on sintering behavior and mechanical properties of ultrafine grained Ti(C, N)-based cermets

    Institute of Scientific and Technical Information of China (English)

    FENG Ping; HE Yue-hui; XIAO Yi-feng; LIU Wen-jun; XIONG Wei-hao

    2007-01-01

    The influences of forming and sintering processes on distortion, cracking as well as mechanical properties of sintered bodies of ultrafine grained Ti(C, N)-based cermets were investigated. The results show that lubricant is indispensable to fabrication of ultrafine Ti(C, N)-based cermets, however, with low binder content in powder mixture, the lubrication action of paraffin is attenuated. A appropriate level of 2% (mass fraction) paraffin is determined for a cermet with binder content of 36% (mass fraction). It is also found that the influence of compaction pressure on distortion and cracking of sintered bodies presents a complex relationship. A relatively lower or higher compaction pressure, less than 100 MPa and more than 400 MPa respectively, favors uniform density distribution in green compact. The heating rate of sintering should be strictly controlled. Too fast heating rate results in enclosed pores to burst and forms large size pores in sintering body. A heating rate of 3 ℃/min is recommended.

  11. Improving 6061-Al Grain Growth and Penetration across HIP-Bonded Clad Interfaces in Monolithic Fuel Plates: Initial Studies

    Energy Technology Data Exchange (ETDEWEB)

    Hackenberg, Robert E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); McCabe, Rodney J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Montalvo, Joel D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Clarke, Kester D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dvornak, Matthew J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Edwards, Randall L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Crapps, Justin M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trujillo, R. Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aikin, Beverly [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vargas, Victor D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hollis, Kendall J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lienert, Thomas J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Forsyth, Robert T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harada, Kiichi L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2013-05-06

    Grain penetration across aluminum-aluminum cladding interfaces in research reactor fuel plates is desirable and was obtained by a legacy roll-bonding process, which attained 20-80% grain penetration. Significant grain penetration in monolithic fuel plates produced by Hot Isostatic Press (HIP) fabrication processing is equally desirable but has yet to be attained. The goal of this study was to modify the 6061-Al in such a way as to promote a much greater extent of crossinterface grain penetration in monolithic fuel plates fabricated by the HIP process. This study documents the outcomes of several strategies attempted to attain this goal. The grain response was characterized using light optical microscopy (LOM) electron backscatter diffraction (EBSD) as a function of these prospective process modifications done to the aluminum prior to the HIP cycle. The strategies included (1) adding macroscopic gaps in the sandwiches to enhance Al flow, (2) adding engineering asperities to enhance Al flow, (3) adding stored energy (cold work), and (4) alternative cleaning and coating. Additionally, two aqueous cleaning methods were compared as baseline control conditions. The results of the preliminary scoping studies in all the categories are presented. In general, none of these approaches were able to obtain >10% grain penetration. Recommended future work includes further development of macroscopic grooving, transferred-arc cleaning, and combinations of these with one another and with other processes.

  12. Effects of feeding processed corn stover and distillers grains on growth performance and metabolism of beef cattle.

    Science.gov (United States)

    Chapple, W P; Cecava, M J; Faulkner, D B; Felix, T L

    2015-08-01

    Objectives were to evaluate the effects of replacing corn in feedlot finishing diets with processed corn stover (CS), processed by various combinations of chemical and physical methods, and modified wet distillers grain with solubles (MWDGS) on growth performance, carcass characteristics, digestibility, and ruminal metabolism of cattle. Corn stover was physically processed (ground or extruded) and chemically processed with alkaline agents (CaO and NaOH) to reduce the crystallinity of the lignocellulosic structure. In Exp. 1 steers ( = 18, initial BW = 385 ± 32 kg) and heifers ( = 41, initial BW = 381 ± 27 kg) were allotted to 1 of 5 dietary treatments: 1) 55% dry, cracked corn, 35% MWDGS, 5% vitamin-mineral supplement, and 5% untreated ground CS (), 2) CS treated with 5% CaO (DM basis) and stored in an Ag-Bag (BGCS), 3) CS treated with 5% CaO (DM basis) and extruded (5 EXCS), 4) CS treated with 4% CaO and 1% NaOH (DM basis) and extruded (4,1 EXCS), or 5) CS treated with 3% CaO and 2% NaOH (DM basis) and extruded (3,2 EXCS). Extruded CS was hydrated to 34% moisture, then an additional 16% water was added, as a solution carrying CaO or NaOH or both, via a calibrated pump during processing through a dual-shafted encased extruder (Readco Kurimoto Continuous Processor, York, PA) with the desired exiting temperature of 76.7°C ± 2.8°C. All treated CS diets contained 20% CS and 40% MWDGS (DM basis) to replace 20% corn when compared to CON. There were no effects ( ≥ 0.20) of dietary treatment on ADG, G:F, 12th-rib back fat, marbling score, LM area, or yield grade. However, cattle fed CON had increased ( = 0.02) DMI compared to cattle fed the treated CS diets. In Exp. 2, using the same diets as fed in Exp. 1, ruminally cannulated steers ( = 5; initial BW = 417 ± 21 kg) were fed for 90% of ad libitum intake in a 5 × 5 Latin square design. Apparent digestibility of NDF and ADF increased ( corn with treated CS in feedlot diets containing MWDGS increased fiber

  13. Controllable preparation of Ni nanoparticles for catalysis of coiled carbon fibers growth.

    Science.gov (United States)

    Jian, Xian; Zhou, Zuowan; Wu, Sixin; Chen, Lei; Zeng, Qing; Wang, Chao

    2014-01-01

    The mass preparation of high-purity coiled carbon fibers (CCFs) remains challenging due to the high complexity and low controllability of reaction. In this work, a controllable growth of Ni particles was fulfilled by liquid phase reduction of nickel sulfate with hydrazine hydrate. The impacts of the reaction temperature, NaOH concentration, and reaction time on the particle size and purity were investigated. The as-deposited Ni particles were characterized by scanning electron microscopy and X-ray diffraction. In addition, these Ni particles were also applied in preparing high-purity CCFs both on graphite and ceramic substrates. The diameter of the as-grown carbon microcoil was about 500 nm, and the related growth mechanism was discussed.

  14. What drives the prescribing of growth hormone preparations in England? Prices versus patient preferences

    Science.gov (United States)

    Chapman, Stephen R; Fitzpatrick, Raymond W; Aladul, Mohammed I

    2017-01-01

    Objective The patent expiry of a number of biological medicines and the advent of biosimilars raised the expectations of healthcare commissioners that biosimilars would reduce the high cost of these medicines and produce potential savings to the NHS. We aimed to examine the prescribing pattern of different growth hormone preparations (ready to use and reconstitution requiring) in primary and secondary care in England to determine relative rates of decrease or increase and identify the possible factors influencing prescribing following the introduction of biosimilar growth hormone in 2008. Design Longitudinal observational study. Setting and data sources Primary care prescribing cost and volume data was derived from the NHS business services authority website, and for secondary care from the DEFINE database, between April 2011 and December 2015. Outcomes Quarterly prescribing analysis to examine trends and measure the relationship between usage and price. Results Expenditure and usage of growth hormone in primary care decreased by 17.91% and 7.29%, respectively, whereas expenditure and usage in secondary care increased by 68.41% and 100%, respectively, between April 2011 and December 2015. The usage of reconstitution requiring products significantly declined in primary care (R²=0.9292) and slightly increased in use in secondary care (R²=0.139). In contrast, the usage of ready-to-use products significantly increased in use in primary (R²=0.7526) and secondary care (R²=0.9633), respectively. Weak or no correlation existed between the usage and price of growth hormone preparations in primary and secondary care. Conclusions The price of growth hormone products was not the key factor influencing the prescribing of the biological medicines. The main driver for specific product selection was the ease of use and the number of steps in dose preparation. Prescribers appear to be taking into account patient preferences rather than cost in their prescribing decisions. PMID

  15. Investigation of Abnormal Grain Growth in a Friction Stir Welded and Spin-Formed Al-Li Alloy 2195 Crew Module

    Science.gov (United States)

    Tayon, Wesley A.; Domack, Marcia S.; Hoffman, Eric K.; Hales, Stephen J.

    2013-01-01

    In order to improve manufacturing efficiency and reduce structural mass and costs in the production of launch vehicle structures, NASA is pursuing a wide-range of innovative, near-net shape manufacturing technologies. A technology that combines friction stir welding (FSW) and spin-forming has been applied to manufacture a single-piece crew module using Aluminum-Lithium (AL-Li) Alloy 2195. Plate size limitations for Al-Li alloy 2195 require that two plates be FSW together to produce a spin-forming blank of sufficient size to form the crew module. Subsequent forming of the FSW results in abnormal grain growth (AGG) within the weld region upon solution heat treatment (SHT), which detrimentally impacts strength, ductility, and fracture toughness. The current study seeks to identify microstructural factors that contribute to the development of AGG. Electron backscatter diffraction (EBSD) was used to correlate driving forces for AGG, such as stored energy, texture, and grain size distributions, with the propensity for AGG. Additionally, developmental annealing treatments prior to SHT are examined to reduce or eliminate the occurrence of AGG by promoting continuous, or uniform, grain growth

  16. The influence of slow cooling on Y211 size and content in single-grain YBCO bulk superconductor through the infiltration-growth process

    Energy Technology Data Exchange (ETDEWEB)

    Ouerghi, A [Systems and Applied Mechanics Laboratory LASMAP, Polytechnic School of Tunisia, Rue El Kawarezmi La Marsa 743, Université de Carthage Tunis (Tunisia); Moutalbi, N., E-mail: nahed.moutalbi@yahoo.fr [Systems and Applied Mechanics Laboratory LASMAP, Polytechnic School of Tunisia, Rue El Kawarezmi La Marsa 743, Université de Carthage Tunis (Tunisia); Noudem, J.G. [CRISMAT-ENSICAEN (UMR-CNRS 6508), Université de Caen-Basse-Normandie, F-14050 Caen (France); LUSAC, Université de Caen-Basse-Normandie F-50130 Cherbourg-Octeville (France); M' chirgui, A. [Systems and Applied Mechanics Laboratory LASMAP, Polytechnic School of Tunisia, Rue El Kawarezmi La Marsa 743, Université de Carthage Tunis (Tunisia)

    2017-03-15

    Highlights: • YBCO bulk superconductors are produced by optimized Seeded Infiltration and Growth process. • The slow cooling time, in a fixed slow cooling temperature window, affects considerably the surface morphology and the bulk’s microstructure. • The Y211 particle’s size and content depend on the slow cooling time and its distribution behavior changes from one position to another. • There is an optimum slow cooling time, estimated to 88h, over which the shrinkage for both the liquid phase and the Y211 pellet is maximal, without any improvement of the crystal grain growth. • The magnetic trapped flux distribution for a given sample brings out the single grain characteristic. - Abstract: Highly textured YBa{sub 2}Cu{sub 3}O{sub 7-δ} (Y123) superconductors were produced using modified Textured Top Seeded Infiltration Growth (TSIG) process. The liquid source is made of only Y123 powder whereas the solid source is composed of Y{sub 2}BaCuO{sub 5} (Y211) powder. We aim to control the amount of liquid that infiltrates the solid pellet, which in turn controls the final amount of Y{sub 2}BaCuO{sub 5} particles in Y123 matrix. The effect of the slow cooling kinetics on sample morphology, on grain growth and on final microstructure was too investigated. It is shown that appropriate slow cooling time may also contribute to the control of the amount of Y211 inclusions in the final structure of Y123 bulk. We report herein the Y211 particle size and density distribution in the whole Y123 matrix. The present work proves that finest Y211 particles locate under the seed and that their size and density increase with distance from the seed.

  17. Influence of porosity on densification and grain growth kinetics of Ce0.9Gd0.1O1.95 tape

    DEFF Research Database (Denmark)

    Ni, De Wei; Esposito, Vincenzo; Foghmoes, Søren Preben Vagn;

    Gadolinium doped-ceria (CGO) is an important material that offers high stability, tolerance against harsh environments and high ionic and electronic conductivity at high temperatures. For most of its applications, CGO is applied as a thin dense layer on a porous support structure. However, highly...... porous layer allowing gas flow is necessary in catalytic and in gas purification devices. During the sintering with shrinkage, the total solid volume is maintained to be a constant value but the shape and size of each particle change with the formation of grain boundaries. This change in solid particles...... is accompanied by the change of shape, size and fraction of pores in a given volume. Therefore, porosity can be treated as an extra phase during sintering study. In this work, we presented the densification and grain growth behaviour of Ce0.9Gd0.1O1.95 tape cast layers with different percentage of porosity...

  18. Grain refinement of AZ31 magnesium alloy by Al-Ti-C-Y master alloy

    Institute of Scientific and Technical Information of China (English)

    XU Chunxiang; LU Binfeng; L(U) Zhengling; LIANG Wei

    2008-01-01

    Al-Ti-C-Y master alloy was prepared by combining SHS technique and melting-casting method. The microstructure of master alloy and its grain-refining effect on AZ31 alloy were investigated by means of OM, XRD, SEM and EDS. Experimental results indicated that the prepared master alloy consisted of α-Al, TiAl3, TiC and Al3Y phases, and exhibited good grain-refining performance of AZ31 alloy. Morphology of α-Mg changed from coarse dendritic to fine equiaxed and the average grain size of α-Mg matrix reduced from the original 580 to 170 μm after adding 1.0 wt.% master alloy. The grain refining efficiency of Al-Ti-C-Y master alloy on AZ31 alloy was mainly attributed to heterogeneous nucleation of TiC particles and grain growth restriction of Al-Y compound or TiC at grain boundaries.

  19. Preparation of Nutritional Coarse Grain Powder by Twin-Screw Extrusion%膨化营养杂粮粉的挤压制备工艺研究

    Institute of Scientific and Technical Information of China (English)

    郑志; 王丽娟; 杨雪飞; 祁斌; 赖华楠; 姜绍通

    2012-01-01

    分别以80目玉米粉、糙米粉、燕麦粉、麦麸粉作为营养杂粮粉生产原料,研究物料含水量、螺杆转速、机筒温度对产品品质指标径向膨化度、糊化度和吸水性指数的影响,在此基础上设计正交试验,确定挤压技术制备膨化营养杂粮粉的最佳工艺参数为物料含水量15%、螺杆转速130r/min、机筒温度160℃,此时产品径向膨化度为3.26,糊化度为91.87%,吸水性指数为491.8%。%Nutritional coarse grain powder was developed using twin-screw extrusion technology with mixed powder of corn, unpolished rice, oat and wheat bran. The effects of water content in raw materials, screw speed and barrel temperature on quality indices including radial expansion degree, gelatinizafion degree and water-absorbing capacity of extruded powder were investigated. An orthogonal array design was used to determine the optimal process parameters for the preparation of nutritional coarse grain powder as follows: water content in raw materials of 15%, screw speed of 130 r/min, and barrel temperature of 160 ℃. The radial expansion degree, gelatinization degree and water-absorbing capacity of the obtained product were 3.26, 91.87 % and 491.8 %, respectively.

  20. Growth performance, feeding behavior, and selected blood metabolites of Holstein dairy calves fed restricted amounts of milk: No interactions between sources of finely ground grain and forage provision.

    Science.gov (United States)

    Mirzaei, M; Khorvash, M; Ghorbani, G R; Kazemi-Bonchenari, M; Ghaffari, M H

    2017-02-01

    The objective of this study was to investigate the effects of grain sources and forage provision on growth performance, blood metabolites, and feeding behaviors of dairy calves. Sixty 3-d-old Holstein dairy calves (42.2 ± 2.5 kg of body weight) were used in a 2 × 3 factorial arrangement with the factors being grain sources (barley and corn) and forage provision (no forage, alfalfa hay, and corn silage). Individually housed calves were randomly assigned (n = 10 calves per treatment: 5 males and 5 females) to 6 treatments: (1) barley grain (BG) without forage supplement, (2) BG with alfalfa hay (AH) supplementation, (3) BG with corn silage (CS) supplementation, (4) corn grain (CG) without forage supplement, (5) CG with AH supplementation, and (6) CG with CS supplementation. All calves had ad libitum access to water and starter feed throughout the experiment. All calves were weaned on d 49 and remained in the study until d 63. Starter feed intake and average daily gain (ADG) was greater for calves fed barley than those fed corn during the preweaning and overall periods. Calves supplemented with CS had greater final body weight and postweaning as well as overall starter feed intake than AH and non-forage-supplemented calves. During the preweaning and overall periods, feeding of CS was found to increase ADG compared with feeding AH and nonforage diets. However, feed efficiency was not affected by dietary treatments. Calves supplemented with CS spent more time ruminating compared with AH and control groups; nonnutritive oral behaviors were the greatest in non-forage-supplemented calves. Regardless of the grain sources, the rumen pH value was greater for AH calves compared with CS and non-forage-supplemented calves. Blood concentration of BHB was greater for CS-supplemented calves compared with AH and non-forage-supplemented calves. Furthermore, body length and heart girth were greater for calves fed barley compared with those fed corn, and also in forage

  1. Combining x-ray diffraction contrast tomography and mesoscale grain growth simulations in strontium titanate: An integrated approach for the investigation of microstructure evolution

    DEFF Research Database (Denmark)

    Syha, Melanie; Baürer, Michael; Rheinheimer, Wolfgang

    2013-01-01

    Motivated by the recently reported a growth anomaly in strontium titatate bulk samples1, the microstructure of bulk strontium titanate has been investigated by an integrated approach comprising conventional metallography, three dimensional X-ray diffraction contrast tomography (DCT)2, and the obs......Motivated by the recently reported a growth anomaly in strontium titatate bulk samples1, the microstructure of bulk strontium titanate has been investigated by an integrated approach comprising conventional metallography, three dimensional X-ray diffraction contrast tomography (DCT)2......, and the observation of pore shapes in combination with mesoscale grain growth simulations. The microstructural evolution in strontium titanate has been characterized alternating ex-situ annealing and high energy X-ray DCT measurements, resulting in three dimensional microstructure reconstructions which...

  2. The Preparation, Preparation Mechauism and Properties of Extra Coarse-grained WC-Co Hardmetals%超粗晶WC-Co硬质合金的制备方法与机理及性能研究

    Institute of Scientific and Technical Information of China (English)

    聂洪波

    2016-01-01

    采用加入球磨活化的细WC粉的方法,成功制备了WC截线晶粒度大于6.5μm的超粗晶硬质合金。对制备机理进行了分析,并对所制备超粗晶硬质合金的金相、热导率、断裂韧性和抗氧化性等进行测定。结果表明:活化细粉在固相烧结阶段全部消失,可以增加烧结活性并抑制超粗晶粒溶解、粒径减小;超粗晶硬质合金WC晶粒度分布窄,晶界平直;热导率和断裂韧性是同样钴含量为0.8μmWC-Co硬质合金的两倍以上,具有优良断裂韧性是由于其可以发生塑性变形;在超粗晶硬质合金中添加镍并不能显著提高抗氧化性。%Extra coarse-grained hardmetals with WC linear-intercept grain size of more than 6.5μm were prepared successfully by adding activated fine WC powders during ball milling. Its metallography, thermal conductivity, fracture toughness and oxidation resistance of these hardmetals were tested. The results indicated that the activated powders, which improved the sintering activity and inhibited extra coarse WC powders dissolution, disappeared during solid phase sintering stage. The grain boundaries of WC with narrow size distribution are straight. Thermal conductivities and fracture toughness are more than two times of 0.8 μm WC hardmetals with the same cobalt content. The favorable fracture toughness was attributed to the plastic deformation of extra coarse-grained harmetals. The oxidation resistance of the hardmetals with addition of nickel hasn't significantly improved.

  3. Fenton process-affected transformation of roxarsone in paddy rice soils: Effects on plant growth and arsenic accumulation in rice grain.

    Science.gov (United States)

    Qin, Junhao; Li, Huashou; Lin, Chuxia

    2016-08-01

    Batch and greenhouse experiments were conducted to examine the effects of Fenton process on transformation of roxarsone in soils and its resulting impacts on the growth of and As uptake by a rice plant cultivar. The results show that addition of Fenton reagent markedly accelerated the degradation of roxarsone and produced arsenite, which was otherwise absent in the soil without added Fenton reagent. Methylation of arsenate was also enhanced by Fenton process in the earlier part of the experiment due to abundant supply of arsenate from Roxarsone degradation. Overall, addition of Fenton reagent resulted in the predominant presence of arsenate in the soils. Fenton process significantly improved the growth of rice in the maturity stage of the first crop, The concentration of methylated As species in the rice plant tissues among the different growth stages was highly variable. Addition of Fenton reagent into the soils led to reduced uptake of soil-borne As by the rice plants and this had a significant effect on reducing the accumulation of As in rice grains. The findings have implications for understanding As biogeochemistry in paddy rice field receiving rainwater-borne H2O2 and for development of mitigation strategies to reduce accumulation of As in rice grains.

  4. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  5. Effects of Nano-Zinc oxide and Seed Inoculation by Plant Growth Promoting Rhizobacteria (PGPR on Yield, Yield Components and Grain Filling Period of Soybean (Glycine max L.

    Directory of Open Access Journals (Sweden)

    R. Seyed Sharifi

    2016-02-01

    promoting rhizobacteria application on yield, yield components and grain filling period of soybean. Materials and Methods In order to study the effects of Nano-Zinc oxide and seed inoculation with Brady rhizobium and plant growth promoting rhizobacteria on yield and some agronomic characteristics of soybean, a factorial experiment based on randomized complete block design with three replications was conducted in 2013 at the research farm of the Islamic Azad University, Ardabil Branch. Factors were included foliar application of Nano-Zinc oxide at four levels (Zero as control, 0.3, 0.6 and 0.9 g l-1 and seed inoculation with Brady rhizobium and plant growth promoting rhizobacteria at five levels (without inoculation as control, seed inoculation with Brady rhizobium japanicum, seed inoculation with Brady rhizobium japanicum+Azosprillum lipoferum strain OF, seed inoculation with Brady rhizobium japanicum+Psedomonas putida, seed inoculation with Brady rhizobium japanicum+ Azosprillum lipoferum strain OF+ Psedomonas putida. Results and Discussion The results of growth indices showed that the maximum total dry matter (530 g m-2, crop growth rate (9.48 g.m-2.day-1 and relative growth rate (0.1 g.g-1.day-1 were obtained at foliar application of 0.9 g l-1 Nano-Zinc oxide×seed inoculation with rhizobium+Azosprillum+ Psedomonas and the least of these indices were obtained without of foliar application Nano-Zinc oxide × seed inoculation. The results showed that plant height, the number of nodules per plant, the number of pod per plant, grain yield and grain 100 weight were significantly affected by Nano-Zinc oxide, seed inoculation and interaction of Nano-Zinc oxide×seed inoculation. Maximum of plant height, grain 100 weight, the number of nodules per plant and grain yield were obtained at foliar application of 0.9 g l-1 of Nano-Zinc oxide×seed inoculation with rhizobium and PGPR. Dry weight of nodules per plant, the number of pod per plant and the number of grains per plant

  6. Milk-derived ribonuclease 5 preparations induce myogenic differentiation in vitro and muscle growth in vivo.

    Science.gov (United States)

    Knight, Matthew I; Tester, Angus M; McDonagh, Matthew B; Brown, Andrew; Cottrell, Jeremy; Wang, Jianghui; Hobman, Peter; Cocks, Benjamin G

    2014-12-01

    Ribonuclease 5, also known as angiogenin, is a stable and abundant ribonuclease in milk whey protein, which is able to regulate several cellular functions, including capillary formation, neuron survival, and epithelial cell growth. Ribonuclease 5 is important for protein synthesis directly stimulating rRNA synthesis in the nucleolus. Here, we show that biologically active RNase5 can be purified from bovine milk. Furthermore, we show that milk-derived RNase5 directly stimulates muscle cell differentiation in vitro, inducing C2C12 cell differentiation and myogenesis. When supplemented into the diet of healthy adult mice, milk-derived RNase5 preparations promoted muscle weight gain and grip strength. Collectively, these data indicate that milk-derived RNase5 preparations exhibit a novel role in skeletal muscle cell function.

  7. Effect of wheat dried distillers grains with solubles and fibrolytic enzymes on ruminal fermentation, digestibility, growth performance, and feeding behavior of beef cattle.

    Science.gov (United States)

    He, Z X; Walker, N D; McAllister, T A; Yang, W Z

    2015-03-01

    Two experiments were conducted to evaluate the effect of wheat dried distillers grains with solubles (DDGS) and fibrolytic enzymes (FE) on ruminal fermentation, in situ ruminal and in vivo total tract digestibility, growth performance, and feeding behavior of growing beef cattle. In Exp. 1, 6 ruminally cannulated Angus heifers (average BW of 794 ± 44.2 kg) were used in a 6 × 6 Latin square design with 2 × 3 factorial arrangement of treatments. Treatments were a control diet consisting of 50% barley silage, 10% grass hay, and 40% barley grain-based concentrate (CON) and the CON with 15% DDGS substituted for barley grain (WDG) combined with either 0, 1, or 2 mL FE/kg diet DM, respectively. Inclusion of DDGS increased total tract digestibility of CP ( time spent at the feed bunk. Supplementing FE decreased ( time at the bunk and increased ( meal frequency ( = 0.02) were greater but eating duration was shorter ( < 0.01) for steers fed the WDG than for those fed the CON. These results indicate that inclusion of wheat DDGS in a growing diet increased total tract digestibility of NDF and CP and improved the feed efficiency of steers. Moreover, supplementation of FE in barley silage-based growing diets may also have the potential to increase profits, with the evidence of the trend for a decline on DMI without decreasing ADG when adding FE.

  8. Section 1: Interfacial reactions and grain growth in ferroelectric SrBi{sub 2}Ta{sub 2}O (SBT) thin films on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, B.D.; Zhang, X.; Desu, S.B. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)] [and others

    1997-04-01

    Much of the cost of traditional infrared cameras based on narrow-bandgap photoelectric semiconductors comes from the cryogenic cooling systems required to achieve high detectivity. Detectivity is inversely proportional to noise. Generation-recombination noise in photoelectric detectors increases roughly exponentially with temperature, but thermal noise in photoelectric detectors increases only linearly with temperature. Therefore `thermal detectors perform far better at room temperature than 8-14 {mu}m photon detectors.` Although potentially more affordable, uncooled pyroelectric cameras are less sensitive than cryogenic photoelectric cameras. One way to improve the sensitivity to cost ratio is to deposit ferroelectric pixels with good electrical properties directly on mass-produced, image-processing chips. `Good` properties include a strong temperature dependence of the remanent polarization, P{sub r}, or the relative dielectric constant, {epsilon}{sub r}, for sensitive operation in pyroelectric or dielectric mode, respectively, below or above the Curie temperature, which is 320 C for SBT. When incident infrared radiation is chopped, small oscillations in pixel temperature produce pyroelectric or dielectric alternating currents. The sensitivity of ferroelectric thermal detectors depends strongly on pixel microstructure, since P{sub r} and {epsilon}{sub r} increase with grain size during annealing. To manufacture SBT pixels on Si chips, acceptable SBT grain growth must be achieved at the lowest possible oxygen annealing temperature, to avoid damaging the Si chip below. Therefore current technical progress describes how grain size, reaction layer thickness, and electrical properties develop during the annealing of SBT pixels deposited on Si.

  9. Study of grain growth in pellets of U O{sub 2}; Estudo do crescimento de graos de UO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Galinari, Clenice M.; Lameiras, Fernando S. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    1997-12-01

    The microstructure of a polycrystalline material has a strong influence on their properties, such as mechanical strength, electrical conductivity, optical transmission and magnetic susceptibility. The Uranium dioxide (U O{sub 2}) have been studied and used in water cooled nuclear reactors since the beginning of the nuclear technology, because it has the required characteristics for a nuclear fuel. The U O{sub 2} is widely used in the form of pellets manufactured through powder compaction and sintering. The manufacturing parameters directly affect the fuel microstructure. The purpose of this paper is to evaluate the grain growth in pellets of U O{sub 2} after resintering and the applicability of Lameiras model on microparticle restructuring. The fuel pellets were obtained through direct pelletizing with compaction pressure at 400 MPa, sintering temperature at 1700{sup 0} C, resintering temperature at 1730{sup 0} C, and variation of the resintering times from 1 to 5 hours. The grain size distribution and the grain average diameter were measured with the Quantikov image analyzer that employs the Saltykov`s method. (author). 12 refs., 5 figs., 1 tab.

  10. Prospecting plant growth promoting bacteria and cyanobacteria as options for enrichment of macro- and micronutrients in grains in rice–wheat cropping sequence

    Directory of Open Access Journals (Sweden)

    Anuj Rana

    2015-12-01

    Full Text Available The influence of plant growth promoting bacteria (PGPB and cyanobacteria, alone and in combination, was investigated on micronutrient enrichment and yield in rice–wheat sequence, over a period of two years. Analysis of variance (ANOVA in both crops indicated significant differences in soil dehydrogenase activity and micronutrient enrichment in grains (Fe, Zn in rice, and Cu, Mn in wheat. The combined inoculation of Anabaena oscillarioides CR3, Brevundimonas diminuta PR7, and Ochrobactrum anthropi PR10 (T6 significantly increased nitrogen, phosphorus, and potassium (NPK content and improved rice yield by 21.2%, as compared to the application of recommended dose of NPK fertilizers (T2. The treatment T5 (Providencia sp. PR3 + B. diminuta PR7 + O. anthropi PR10 recorded an enhancement of 13–16% in Fe, Zn, Cu, and Mn concentrations, respectively, in rice grains. In wheat, Providencia sp. PW5 (T6 recorded the highest yield (5.23 Mg ha−1 and significantly higher enrichment of Fe and Cu (44–45% in the grains. This study highlighted the promise of combinations of cyanobacteria/bacteria and their synergistic action in biofortification and providing savings of 40–60 kg N ha−1. Future focus needs to be towards integrating such promising environment-friendly and environmentally sustainable options in nutrient management strategies for this cropping sequence.

  11. Altered expression of the PIR/NRT1 homolog OsPTR9 affects nitrogen use efficiency,growth and grain yield in rice

    Institute of Scientific and Technical Information of China (English)

    FANG; Zhongming; YANG; Xing; Xia; Kuaifei; Marianne; Suter; Grotemeyer; Stefan; Meier; Doris; Rentsch; XU; Xinlan; ZHANG; Mingyong

    2015-01-01

    The plant PTR/NRT1(peptide transporter/nitrate transporter 1)gene family com—prises di/tripeptide and low affinity nitrate transporters;some members also recognize other substrates like phytohormones(auxin and abscisic acid)and defence compound glucosinolate.Little is known about members of this gene family in rice(Oryza sativa L.).Here,we report the influence of altered OsPTR9 expression on nitrogen use efficiency,growth and grain yield.OsPTR9 expression is regulated by the exogenous nitrogen source and by the day-night cycle.Elevated expression of OsPTR9 in transgenic rice plants resulted in enhanced ammonium uptake,promotion of lateral root formation,and increased grain yield.On the other hand,downregulation of OsPTR9 in a T-DNA insertion line(osptr9)and in the 0sPTR9一RNAi rice plants had the opposite effect.These results suggest that OsPTR9 may hold potential in improving nitrogen use efficiency and grain yield for rice breeding.

  12. Food consumption and growth rates of juvenile black carp fed natural and prepared feeds

    Science.gov (United States)

    Hodgins, Nathaniel C.; Schramm, Harold L.; Gerard, Patrick D.

    2014-01-01

    The introduced mollusciphagic black carp Mylopharyngodon piceus poses a significant threat to native mollusks in temperate waters throughout the northern hemisphere, but consumption rates necessary to estimate the magnitude of impact on mollusks have not been established. We measured food consumption and growth rates for small (77–245 g) and large (466–1,071 g) triploid black carp held individually under laboratory conditions at 20, 25, and 30°C. Daily consumption rates (g food · g wet weight fish−1·d−1·100) of black carp that received prepared feed increased with temperature (small black carp 1.39–1.71; large black carp 1.28–2.10), but temperature-related increases in specific growth rate (100[ln(final weight) - ln(initial weight)]/number of days) only occurred for the large black carp (small black carp −0.02 to 0.19; large black carp 0.16–0.65). Neither daily consumption rates (5.90–6.28) nor specific growth rates (0.05–0.24) differed among temperatures for small black carp fed live snails. The results of these laboratory feeding trials indicate food consumption rates can vary from 289.9 to 349.5 J·g−1·d−1 for 150 g black carp receiving prepared feed, from 268.8 to 441.0 J·g−1·d−1for 800 g black carp receiving prepared feed, and from 84.8 to 90.2 J·g−1·d−1 for 150 g black carp that feed on snails. Applying estimated daily consumption rates to estimated biomass of native mollusks indicates that a relatively low biomass of bla

  13. Zeolite and clay-mineral induced resistivity in simulated reservoir. [Artificial cores prepared by mixing and compacting clinoptilolite, smectite and illite, with medium-grained quartz sand

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, W.R.; Williford, C.W. (Mississippi Univ., University, MS (USA))

    1991-02-01

    Clay-minerals dispersed in reservoir sands affect electric log response and register reduced resistivity values. Natural zeolites however, with large microporosities and water content could have a greater affect on resistivity measurements. Resistivity values were measured on a series of artificial cores prepared by mixing and compacting various percentages each of clinoptilolite, smectite and illite, with a medium-grained, moderately sorted quartz sand. Various concentrations of NaCl solution mixed with 39 API crude oil were circulated through each core. Impedance measurements were taken, resistance values segregated, and resistivities determined for each core. Water saturation values were calculated from the empirical resistivity values and porosities using a modified Simandoux equation. These values appeared to be much higher for those cores which contained the zeolite clinoptilolite. Clinoptilolite, when dispersed in a simulated reservoir sand and treated as a dispersed smectite or illite, produced inflated saturation values. This inflation effect is thought to be due to the more extensive microporosity and larger micropore water content of the zeolite. Therefore, from the empirical aspect, resistivity measurements of reservoir sands containing a dispersed zeolite, rather than a clay-mineral, would probably yield misleading water saturation values. 3 figs., 26 refs., 3 tabs.

  14. Austenite grain growth behavior of a 82B high carbon steel%82B高碳钢奥氏体晶粒长大行为

    Institute of Scientific and Technical Information of China (English)

    金桂香; 王福明; 李克非; 付军; 李长荣

    2013-01-01

    利用直线截点法计算各试样的奥氏体平均晶粒尺寸,得出82B高碳钢的奥氏体粗化温度为950℃,通过Thermo-calc热力学计算和能谱分析可知,晶粒粗化的主要原因是950℃时V、Ti、Nb碳氮化物数量的大大减少,即析出相粒子钉扎作用的减弱和消除.随着加热温度的升高和保温时间的延长,82B高碳钢奥氏体晶粒尺寸增大,其生长模型的公式为D=6.82×104t0079 exp(-8.04×104/RT).当加热温度为1000℃,保温时间为60~90 min时,82B原奥氏体晶粒尺寸小于67μm,晶粒细小均匀,且微合金元素V充分溶解在奥氏体中.%The austenite grain coarsening temperature of 82B high carbon steel is 950℃ by measuring average grain size with linear cut point method.The results of EDS analysis and thermodynamic calculation based on Thermo-calc show that the main reason of grain coarsening is that the quantity of carbonitrides of elements V,Ti and Nb is decreased heavily for the steel heating at 950 ℃,which means the pinning effect of the precipitated phase particles is weakened or eliminated.The average austenite grain size increases with the increasing of the heating temperature and the holding time,which can be described by the austenite grain growth model D =6.82 × 104t0079exp(-8.04 × 104/RT).When the heating temperature is 1000 ℃ and the holding time is between 60 min and 90 min,the austenite grain size of 82B steel is uniform and smaller than 67 μm,and the micro-alloying element V is dissolved into austenite adequately.

  15. Preparation

    Directory of Open Access Journals (Sweden)

    M.M. Dardir

    2014-03-01

    Full Text Available Some hexanamide-mono and di-linoleniate esters were prepared by the reaction of linolenic acid and hexanamide (derived from the reaction of hexanoic acid and diethanolamine. The chemical structure for the newly prepared hexanamide-mono and di-linoleniate esters were elucidated using elemental analysis, (FTIR, H 1NMR and chemical ionization mass spectra (CI/Ms spectroscopic techniques. The results of the spectroscopic analysis indicated that they were prepared through the right method and they have high purity. The new prepared esters have high biodegradability and lower toxicity (environmentally friendly so they were evaluated as a synthetic-based mud (ester-based mud for oil-well drilling fluids. The evaluation included study of the rheological properties, filtration and thermal properties of the ester based-muds formulated with the newly prepared esters compared to the reference commercial synthetic-based mud.

  16. Preparation, Growth Mechanisms and Characterizations of ZnSe Films via the Solvothermal Method

    Institute of Scientific and Technical Information of China (English)

    LI Huan-yong; JIE Wan-qi; ZHAO Hai-tao

    2006-01-01

    With diethylamine as a solvent, ZnSe films were formed on the Si substrate directly from zinc and selenium through the modified solvothermal method. The effects of holding temperature, deposition time and substrate surface treatment on the quality and morphologies of the ZnSe films were investigated. The growth mechanism of ZnSe films was proved to be a layer-nucleation growth process, which was tied in with the Stranski-Krastanov (SK) model. ZnSe films were identified by the X-ray diffraction pattern (XRD), the scanning electron microscope (SEM), the X-ray photoelectron spectroscope (XPS) and the photoluminescence (PL) techniques. The results indicate that the modified solvothermal method with diethylamine as a solvent is suitable to prepare high quality ZnSe films.

  17. Well-Hidden Grain Boundary in the Monolayer MoS2 Formed by a Two-Dimensional Core-Shell Growth Mode.

    Science.gov (United States)

    Zhang, Wenting; Lin, Yue; Wang, Qi; Li, Weijie; Wang, Zhifeng; Song, Jiangluqi; Li, Xiaodong; Zhang, Lijie; Zhu, Lixin; Xu, Xiaoliang

    2017-09-22

    Guided by the hexagonal lattice symmetry, triangles and hexagons are the most basic morphological units for two-dimensional (2D) transition metal dichalcogenides (TMDs) synthesized by chemical vapor deposition (CVD). Also, it is widely acknowledged that these units start from the single nucleation site and then grow epitaxially. Accordingly, the triangular monolayer (ML) samples are generally considered as single crystals. Here, we report a 2D core-shell growth mode in the CVD process for ML-MoS2, which leads to one kind of "pseudo" single-crystal triangles containing triangular outline grain boundaries (TO-GBs). It is difficult to be optically distinguished from the "true" single-crystal triangles. The weakening of Raman peaks and the remarkable enhancement of photoluminescence (PL) are found at the built-in TO-GBs, which could be useful for high-performance optoelectronics. In addition, the electrical measurements indicate that the TO-GBs are conductive. Furthermore, TO-GBs and the common grain boundaries (CO-GBs) can coexist in a single flake, whereas their optical visibility and optical modifications (Raman and PL) are quite different. This work is helpful in further understanding the growth mechanism of 2D TMD materials and may also play a significant role in related nanodevices.

  18. Growth model and metabolic activity of brewing yeast biofilm on the surface of spent grains: a biocatalyst for continuous beer fermentation.

    Science.gov (United States)

    Brányik, Tomás; Vicente, António A; Kuncová, Gabriela; Podrazký, Ondrej; Dostálek, Pavel; Teixeira, José A

    2004-01-01

    In the continuous systems, such as continuous beer fermentation, immobilized cells are kept inside the bioreactor for long periods of time. Thus an important factor in the design and performance of the immobilized yeast reactor is immobilized cell viability and physiology. Both the decreasing specific glucose consumption rate (q(im)) and intracellular redox potential of the cells immobilized to spent grains during continuous cultivation in bubble-column reactor implied alterations in cell physiology. It was hypothesized that the changes of the physiological state of the immobilized brewing yeast were due to the aging process to which the immobilized yeast are exposed in the continuous reactor. The amount of an actively growing fraction (X(im)act) of the total immobilized biomass (X(im)) was subsequently estimated at approximately X(im)act = 0.12 g(IB) g(C)(-1) (IB = dry immobilized biomass, C = dry carrier). A mathematical model of the immobilized yeast biofilm growth on the surface of spent grain particles based on cell deposition (cell-to-carrier adhesion and cell-to-cell attachment), immobilized cell growth, and immobilized biomass detachment (cell outgrowth, biofilm abrasion) was formulated. The concept of the active fraction of immobilized biomass (X(im)act) and the maximum attainable biomass load (X(im)max) was included into the model. Since the average biofilm thickness was estimated at ca. 10 microm, the limitation of the diffusion of substrates inside the yeast biofilm could be neglected. The model successfully predicted the dynamics of the immobilized cell growth, maximum biomass load, free cell growth, and glucose consumption under constant hydrodynamic conditions in a bubble-column reactor. Good agreement between model simulations and experimental data was achieved.

  19. Optimization of C/N ratio for preparation of protein-rich and multi-enzymes feed thallus through synergic fermentation of mixed distillers'grains

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N , their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven-dried thallus The conditions of fermentation are: inoculum size 10%, temperature 30.0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14.693g in a liter liquid medium, maximum utilization rate of carbon source is 98.13% and maximum utilization rate of nitrogen is 78.14%. Optimal C/N is 5.1.

  20. Growth of phase-pure, crack-free single crystals and large-grained polycrystals of molybdenum disilicide

    Science.gov (United States)

    Rossetti, M.

    1970-01-01

    High purity molybdenum disilicide crystals are prepared by zone melting sintered compacts. This method yields single crystals or polycrystals free from macrocracks which allow better measurement and evaluation of mechanical properties.

  1. Aggregation and growth of ZnO quantum dots prepared from sol-gel chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Santilli, C.V.; Pulcinelli, S.H.; Caetano, B.L. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil); Briois, V.B [Synchrotron SOLEIL, Saint-Aubin (France)

    2016-07-01

    Full text: Herein we discuss in depth the mechanisms of growth control of ZnO quantum dots (Q-dot) prepared from the zinc oxy-acetate ethanolic solution by the addition of LiOH. Through in situ monitoring of Q-dot radii and of aggregation index calculated from UV-Vis absorption spectra and small-angle X-ray scattering (SAXS) the aggregation and growth of ZnO nanocrystal was well described from two kinetic models: during the first step (t< 50 min) the structural evolution is controlled by the coalescence caused by the oriented attachment between the nanocrystal aggregates while at the advanced time (t> 50 min) the Q-dot coarsening follows the Ostwald ripening (OR) mechanism. From the higher oriented attachment efficiency observed here as compared with early reported synthesis using NaOH and KOH, we propose an universal mechanism to control coalescence and coarsening of ZnO nanocrystal provided from the shield caused by the adsorption of the alkali cation. From X-ray diffraction and transmission electron microscopy results we demonstrate that this mechanism is also useful to prepare Q-dot powders with controlled size. (author)

  2. The effectiveness evaluation of indigenous microorganism (IMO preparations in the growth of onion (Allium cepa L.

    Directory of Open Access Journals (Sweden)

    Ramón Liriano González

    2015-02-01

    Full Text Available The experiment was done at the Credit and Services Cooperative (CCS “Juan de Mata Reyes”, in Pedro Betancourt municipality, Matanzas. The objective was to evaluate the effectiveness of indigenous microorganisms (IMO preparations on the growth of onion (Allium cepa L., variety Texas Early Grano. Five treatments were studied (control, a 2 mL.m2 treatment before transplantion, a 4 mL.m2 treatment before transplantation, and both 2 and 4 mL.m2 treatments 20 days after transplantion. The experiment was conducted in a randomized block design. The professional statistical pack STATISTICA, version 6.0 for WINDOWS was used for data processing. The results were statistically processed using simple analysis of variance and the Duncan´s multiple comparison Test for media with a level of significance of pd”0.05. The native microorganisms in the preparations were characterized. 60 days after transplantation, the parameters height of plant, number of leaves and diameter of the false stem were evaluated; and at harvest time, the total yield (t.ha-1 and the number of bulbs in diameter category were determined. The best results concerning the height of the plant (cm, diameter of false stem (mm and total yield (t.ha-1.were obtained with the preparation of 2 mL.m2 at the moment of transplantion, and 20 days after the application.

  3. Study of calendula and Gaillardia growth in two composts prepared from agroindustrial wastes.

    Science.gov (United States)

    Roudsari, O Nouri; Akbari, B

    2007-05-01

    Two composts prepared from agroindustrial wastes were assayed as substrates: C1 from brewing waste (yeast and malt) plus lemon tree pruning and C2 from the solid fraction of olive mill wastewater plus olive leaves. Sixteen substrates were prepared by combining each compost with Sphagnum peat or a Commercial Substrate (CS) in different proportions. The nutrients (N and K) provided by the composts, which acted as slow-release fertilizers, influenced especially the development of calendula, although the physical and physicochemical properties such as total pore space and Electrical Conductivity (EC) were also relevant. On the other hand, in the salt-sensitive Gaillardia hybrid, EC and chloride concentration were the main factors influencing growth. The best results were found in substrates prepared by mixing C1 at up to 75% with peat, or at up to 50% with CS, or by mixing C2 at up to 50% with peat or CS, for calendula. For salt-sensitive species such as Gaillardia, adequate substrates for plant development were found for C1 at up to 50% with peat or CS, but the use of C2 should be limited to 25% in mixtures with peat or CS. Therefore, composts of agroindustrial origin such as these can be used as an alternative to peat and CSs for growing ornamental plants, provided the mixture contains at least 25% peat or CS.

  4. Nanocrystal grain growth and device architectures for high-efficiency CdTe ink-based photovoltaics.

    Science.gov (United States)

    Crisp, Ryan W; Panthani, Matthew G; Rance, William L; Duenow, Joel N; Parilla, Philip A; Callahan, Rebecca; Dabney, Matthew S; Berry, Joseph J; Talapin, Dmitri V; Luther, Joseph M

    2014-09-23

    We study the use of cadmium telluride (CdTe) nanocrystal colloids as a solution-processable "ink" for large-grain CdTe absorber layers in solar cells. The resulting grain structure and solar cell performance depend on the initial nanocrystal size, shape, and crystal structure. We find that inks of predominantly wurtzite tetrapod-shaped nanocrystals with arms ∼5.6 nm in diameter exhibit better device performance compared to inks composed of smaller tetrapods, irregular faceted nanocrystals, or spherical zincblende nanocrystals despite the fact that the final sintered film has a zincblende crystal structure. Five different working device architectures were investigated. The indium tin oxide (ITO)/CdTe/zinc oxide structure leads to our best performing device architecture (with efficiency >11%) compared to others including two structures with a cadmium sulfide (CdS) n-type layer typically used in high efficiency sublimation-grown CdTe solar cells. Moreover, devices without CdS have improved response at short wavelengths.

  5. 激光熔注中增强相颗粒对晶粒生长影响的CA模拟∗%Simulation of effect of reinforcement particles on grain growth during laser melt inj ection based on CA

    Institute of Scientific and Technical Information of China (English)

    赵明娟; 邓志成; 赵龙志

    2015-01-01

    基于元胞自动机法,结合 Moore 型邻居定义和晶粒生长理论,建立了增强相颗粒 SiC 对镁合金激光熔注中表层316L不锈钢晶粒生长的影响模型,模型考虑了晶界迁移率和晶界能等因素,实现了不同增强相颗粒体积分数和颗粒尺寸对晶粒生长影响的计算机模拟.结果表明,所建立的模型能较好的模拟晶粒生长过程,所得晶粒生长指数为0.42;增强相颗粒体积分数含量越高,晶粒生长越慢,晶粒尺寸越小;增强相颗粒尺寸越小,晶粒生长的越慢,晶粒尺寸越小,组织越均匀.%Based on the cellular automaton method,the definition of Moore neighbor type and the grain growth theory,a model of simulation for the grain growth process was established,which simulated the influence of the SiC reinforcement particles and 316L stainless steel reinforced the surface of magnesium alloy by laser melt inj ection.Many factors such as grain boundary mobility and grain boundary energy were considered in the mod-el.Simulated the influence of different volume fraction and size of reinforcement particles on the grain growth process were obtained.The results show that:the grain growth process can be simulated very well by the meth-od,the grain growth index can be obtained as 0.42;the higher volume fraction of the particles,the slower the speed of the grain growth,the smaller grain size;the smaller the particles size is,the slower the grain grows, the smaller grain size and the microstructure is more uniform.

  6. Preparation of briquettes on the basis of desintegrated phyto-materials and the admixture of fine-grained coal and coke

    Directory of Open Access Journals (Sweden)

    Jakabský Štefan

    2002-03-01

    Full Text Available The contribution deals with the preparation of small-diameter briquettes on the basis of desintegrated phyto-materials and the admixture of coal and coke. The phyto-materials are classified as a dry biomass that can be, on the one hand, the wastes from wood-working industry,(sawdust, chips, bark, etc. or dried mass from the plant production and, on the other hand, the mass of quick-growing plants cultivated on special plantations. In present time this renewable energy resource attracts attention by its heating value ranging from 10 to 16 MJ.kg-1 (EkoWATT, 2001, a low ash content of 0.5 – 6.5 % and by a low sulphur content in a water free sample of 0.05 –0.12 %.As a phyto-material the spruce sawdusts having a grain size of –2 mm were used. The admixture of brown coal, hard coal and coke with a grain size of 0.040 mm was added to the sawdust and in such way prepared mixtures were subjected to briquetting with the aim to obtain small-diameter briquettes. The influence of admixtures amount on the density, and the suitable briquetting press have been studied. A saleability of briquettes on the basis of phyto-materials is conditioned by their density that must be higher than 1,000 kg.m-3. Thus, an adding of denser material with a relatively high calorific value would enable to attain the required density as well as to retain and/or to improve the main utility properties, i.e. calorific value and ash content.The adding evinces itself in an enhancement of briquetting press, but also density of obtained briquettes is often much higher that required by the market. It was showed that in the case of clear spruce sawdust the density of 1,059 kg.m-3 under the briquetting press of 250 MPa can be attained. According to other results, an admixture of brown coal is not very favourable because briquetting press exceeds the value of 300 MPa. As to hard coal adding, the presses under 250 MPa were achieved at the content of 25 – 30 %. The density of these

  7. Effect of catalyst preparation on the yield of carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, Mariano, E-mail: mescobar@df.uba.a [Dep. Quimica Inorganica, Analitica y Quimica Fisica, FCEyN, UBA, Ciudad Universitaria (1428), Bs As (Argentina); LP and MC, Dep. Fisica, FCEyN, UBA (Argentina); Rubiolo, Gerardo [Unidad de Actividad Materiales, CNEA, Av Gral Paz 1499, San Martin (1650), Bs As (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Candal, Roberto [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Instituto de Fisico-quimica de Materiales, Ambiente y Energia (INQUIMAE), CONICET - UBA (Argentina); Goyanes, Silvia [LP and MC, Dep. Fisica, FCEyN, UBA (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)

    2009-10-01

    Multi-wall carbon nanotubes (MWCNTs) were synthesized by catalytic chemical vapor deposition (CVD) on catalytic iron nanoparticles dispersed in a silica matrix, prepared by sol gel method. In this contribution, variation of gelation condition on catalyst structure and its influence on the yield of carbon nanotubes growth was studied. The precursor utilized were tetraethyl-orthosilicate and iron nitrate. The sols were dried at two different temperatures in air (25 or 80 deg. C) and then treated at 450 deg. C for 10 h. The xerogels were introduced into the chamber and reduced in a hydrogen/nitrogen (10%v/v) atmosphere at 600 deg. C. MWCNTs were formed by deposition of carbon atoms from decomposition of acetylene at 700 deg. C. The system gelled at RT shows a yield of 100% respect to initial catalyst mass whereas the yield of that gelled at 80 deg. C was lower than 10%. Different crystalline phases are observed for both catalysts in each step of the process. Moreover, TPR analysis shows that iron oxide can be efficiently reduced to metallic iron only in the system gelled at room temperature. Carbon nanotubes display a diameter of about 25-40 nm and several micron lengths. The growth mechanism of MWCNTs is base growth mode for both catalysts.

  8. Improvement in skin wrinkles using a preparation containing human growth factors and hyaluronic acid serum.

    Science.gov (United States)

    Lee, Do Hyun; Oh, In Young; Koo, Kyo Tan; Suk, Jang Mi; Jung, Sang Wook; Park, Jin Oh; Kim, Beom Joon; Choi, Yoo Mi

    2015-02-01

    Skin aging is accompanied by wrinkle formation. At some sites, such as the periorbital skin, this is a relatively early phenomenon. We evaluated the anti-wrinkle effect of a preparation containing human growth factor and hyaluronic acid serum on periorbital wrinkles (crow's feet). In total, 23 Korean women (age range: 39-59 years), who were not pregnant, nursing, or undergoing any concurrent therapy, were enrolled in this study. All the patients completed an 8-week trial of twice-daily application of human growth factor and hyaluronic acid serum on the entire face. Efficacy was based on a global photodamage score, photographs, and image analysis using replicas and visiometer analysis every 4 weeks. The standard wrinkle and roughness parameters used in assessing skin by visiometer were calculated and statistically analyzed. Periorbital wrinkles were significantly improved after treatment, with improvements noted both by physician's assessment and visiometer analysis. Topical application of human growth factor and hyaluronic acid was beneficial in reducing periorbital wrinkles.

  9. An assessment of geochemical preparation methods prior to organic carbon concentration and carbon isotope ratio analyses of fine-grained sedimentary rocks

    Science.gov (United States)

    KöNitzer, Sven F.; Leng, Melanie J.; Davies, Sarah J.; Stephenson, Michael H.

    2012-09-01

    This study summarizes organic carbon isotope (δ13C) and total organic carbon (TOC) data from a series of tests undertaken to provide an appropriate methodology for pre-analysis treatment of mudstones from an Upper Carboniferous sedimentary succession, in order to develop a consistent preparation procedure. The main treatments involved removing both inorganic carbonate and hydrocarbons (which might be extraneous) before δ13C and TOC analysis. The results show that decarbonating using hydrochloric acid causes significant reduction in δ13C and total carbon (TC) of the bulk material due to the removal of inorganic carbonate. These changes are most pronounced where soluble calcium carbonate (rather than Ca-Mg-Fe carbonate) is present. Deoiled samples show only slightly higher mean δ13C where visible bitumen was extracted from the bulk sample. Moreover, the isotopic signatures of the extracts are closely correlated to those of their respective bulk samples, suggesting that small yields of hydrocarbons were generated in situ with no isotopic fractionation. In addition, further δ13C and TC analyses were performed on samples where mixing of oil-based drilling mud with brecciated core material had been undertaken. Brecciated mudstone material did not display distinct isotopic signals compared to the surrounding fine-grained material. Overall we show that the most accurate assessment of bulk organic carbon isotopes and concentration in these samples can be achieved through decarbonating the material prior to measurement via the `rinse method'. However, our results support recent findings that pre-analysis acid treatments can cause variable and unpredictable errors in δ13C and TOC values. We believe that, despite these uncertainties, the findings presented here can be applied to paleoenvironmental studies on organic matter contained within sedimentary rocks over a range of geological ages and compositions.

  10. Austenite nucleation and growth observed on the level of individual grains by three-dimensional X-ray diffraction microscopy

    OpenAIRE

    Savran, V.I.; Offerman, S. E.; Sietsma, J.

    2010-01-01

    Austenite nucleation and growth is studied during continuous heating using three-dimensional X-ray diffraction (3-D XRD) microscopy at the European Synchrotron Radiation Facility (ESRF) (Grenoble, France). Unique in-situ observations of austenite nucleation and growth kinetics were made for two commercial medium-carbon low-alloy steels (0.21 and 0.35 wt pct carbon with an initial microstructure of ferrite and pearlite). The measured austenite volume fraction as a function of temperature shows...

  11. The effects of whole grains on nutrient digestibilities, growth performance, and cecal short-chain fatty acid concentrations in young chicks fed ground corn-soybean meal diets.

    Science.gov (United States)

    Biggs, P; Parsons, C M

    2009-09-01

    Five experiments were conducted to evaluate the effects of whole wheat, whole sorghum, or whole barley on nutrient digestibility, growth performance, and cecal short-chain fatty acid concentrations when supplemented primarily at the expense of corn in ground corn-soybean meal control diets. The first 4 experiments utilized New Hampshire x Columbian male chicks. In the first 2 experiments, feeding 5, 10, 15, or 20% whole wheat had no effect on growth performance at 21 d when compared with chicks fed the control diet. The third experiment tested 20, 35, and 50% whole wheat fed from 0 to 21 d of age and showed that a 50% whole wheat diet decreased (Pwhole sorghum reduced (Pwhole barley had similar weight gains to chicks fed a ground corn-soybean meal diet. The fifth experiment with commercial Ross x Ross male broiler chicks evaluated 10 and 20% whole sorghum or whole barley and 20 and 35% whole wheat. Growth at 21 d was unaffected by any dietary treatment. Feed efficiency was decreased (Pwhole wheat and improved (Pwhole barley. Feeding whole grains to chicks resulted in an increase in gizzard weight, even as early as 7 d, in all experiments. Chicks fed diets containing 10 to 20% whole wheat generally had increased MEn values at 3 to 4, 7, 14, and 21 d and also had increased amino acid digestibility at 21 d in one experiment. At 21 d, cecal pH and short-chain fatty acid concentrations in all experiments were unaffected by feeding whole grains to chicks. The results of this study indicated that feeding whole wheat, sorghum, or barley increased gizzard weight, and feeding 10 to 20% whole wheat may increase ME and amino acid digestibility.

  12. Interplay of dust alignment, grain growth, and magnetic fields in polarization: lessons from the emission-to-extinction ratio

    Science.gov (United States)

    Fanciullo, L.; Guillet, V.; Boulanger, F.; Jones, A. P.

    2017-06-01

    Context. Polarized extinction and emission from dust in the interstellar medium (ISM) are hard to interpret, as their dependence on dust optical properties, grain alignment, and magnetic field orientation is complex. This is particularly true in molecular clouds. The aforementioned phenomena are usually considered independently in polarization studies, while it is likely that they all contribute and their effects have yet to be disentangled. Aims: The data available today are not yet used to their full potential. The combination of emission and extinction, in particular, provides information not available from either of them alone. We combine data from the scientific literature on polarized dust extinction with Planck data on polarized emission, and we use them to constrain the possible variations in dust and environmental conditions inside molecular clouds, and especially translucent lines of sight, taking the magnetic field orientation into account. Methods: We focused on the dependence between λmax (the wavelength of maximum polarization in extinction) and other observables such as the extinction polarization, the emission polarization, and the ratio between the two. We set out to reproduce these correlations using Monte Carlo simulations in which we varied the relevant quantities in a dust model, which are grain alignment, size distribution, and magnetic field orientation, to mimic the diverse conditions that are expected inside molecular clouds. Results: None of the quantities we chose can explain the observational data on their own: the best results are obtained when all quantities vary significantly across and within clouds. However, some of the data, most notably the stars with a low ratio of polarization in emission to polarization in extinction, are not reproduced by our simulation. Conclusions: Our results suggest not only that dust evolution is necessary to explain polarization in molecular clouds, but that a simple change in size distribution is not

  13. Comparative effect of salinity on ion accumulation, grain yield and stability salt tolerance degree of barley (Hordeum vulgare L. in different growth stage

    Directory of Open Access Journals (Sweden)

    Abdennaceur Ben Khaled

    2016-12-01

    Full Text Available In arid and semi-arid regions of the world, excess salts in agricultural land can limit crop production. Barley (Hordeum vulgare L. is one of the most salt tolerant crop species. This study was conducted to determine the effects of salinity on seed germination, mineral content and yield production of 14 barley accessions from two regions in the Southern Tunisia. First experiment was conducted in laboratory to test the effect of nine levels of NaCl concentrations in different germination parameter. Second experiments were conducted in a greenhouse. The accessions were grown in soil and exposed to three salinity levels. Salinity decreased significantly the germination rate and the germination rate index for all accessions. Na+ content, total dry matter and grain yield vary significantly with increasing salinity levels. The degree of tolerance varies between accessions in the different growth stage. A significant correlation were observed between ranking using grain yield and multivariate parameter. The tolerance degree based in germination rate and Na+ content don’t present significant correlation with yield ranking. Therefore, ranking using multivariate parameter can be the appropriate method to analysis the tolerance degree of barley under saline conditions. The differences response between accessions of local population of barley “Ardhaoui” reflected an important internal genetic variability against the salinity. This variability could be more explored and used for the barley breeding program. The accessions Ettalah, Chneni Tatouine and Elhezma showed more salt tolerance at 13 dS/m as indicated by the multivariate ranking using germination rate, Na+ content and grain yield.

  14. Potassium Management for Improving Growth and Grain Yield of Maize (Zea mays L.) under Moisture Stress Condition.

    Science.gov (United States)

    Amanullah; Iqbal, Asif; Irfanullah; Hidayat, Zeeshan

    2016-10-03

    Potassium (K) fertilizer management is beneficial for improving growth, yield and yield components of field crops under moisture stress condition in semiarid climates. Field experiments were conducted to study the response of maize (Zea mays L., cv. Azam) to foliar and soil applied K during summer 2013 and 2014. The experiments were carried out at the Agronomy Research Farm of The University of Agriculture Peshawar, Northwest Pakistan under limited irrigation (moisture stress) condition. It was concluded from the results that application of foliar K at the rate of 1-3% and foliar Zn at the rate of 0.1-0.2% was more beneficial in terms of better growth, higher yield and yield components of maize under moisture stress condition. Early spray (vegetative stage) resulted in better growth and higher yield than late spray (reproductive stage). Soil K treated plots (rest) plots performed better than control (K not applied) in terms of improved growth, higher yield and yield components of maize crop. The results further demonstrated that increasing the rate of soil applied K up to 90 kg P ha(-1) in two equal splits (50% each at sowing and knee height) improve growth and maize productivity under semiarid climates.

  15. Potassium Management for Improving Growth and Grain Yield of Maize (Zea mays L.) under Moisture Stress Condition

    Science.gov (United States)

    Amanullah; Iqbal, Asif; Irfanullah; Hidayat, Zeeshan

    2016-01-01

    Potassium (K) fertilizer management is beneficial for improving growth, yield and yield components of field crops under moisture stress condition in semiarid climates. Field experiments were conducted to study the response of maize (Zea mays L., cv. Azam) to foliar and soil applied K during summer 2013 and 2014. The experiments were carried out at the Agronomy Research Farm of The University of Agriculture Peshawar, Northwest Pakistan under limited irrigation (moisture stress) condition. It was concluded from the results that application of foliar K at the rate of 1–3% and foliar Zn at the rate of 0.1–0.2% was more beneficial in terms of better growth, higher yield and yield components of maize under moisture stress condition. Early spray (vegetative stage) resulted in better growth and higher yield than late spray (reproductive stage). Soil K treated plots (rest) plots performed better than control (K not applied) in terms of improved growth, higher yield and yield components of maize crop. The results further demonstrated that increasing the rate of soil applied K up to 90 kg P ha−1 in two equal splits (50% each at sowing and knee height) improve growth and maize productivity under semiarid climates. PMID:27694964

  16. Y_2SiO_5:Ce~(3+) particle growth during sol-gel preparation

    Institute of Scientific and Technical Information of China (English)

    李秀娟; 焦桓; 王晓明; 曾正志; 荆西平

    2010-01-01

    The phosphor Y2SiO5:Ce3+ was prepared by a sol-gel method and the particle growth process was investigated by XRD, SEM and TEM. After heating at 400 °C, the as-dried gel became a powder composed of mixed phases of polycrystalline Y2O3 and amorphous SiO2. With an increase in temperature, the crystallinity of Y2O3 improved. The sample quickly changed to the pure Y2SiO5 phase when it was heated at 1400 °C for 10 min. SEM indicated that the as-dried gel consisted of large porous particles. At an annealing tempe...

  17. Preparation and features of polycaprolactone vascular grafts with the incorporated vascular endothelial growth factor

    Energy Technology Data Exchange (ETDEWEB)

    Sevostyanova, V. V., E-mail: sevostyanova.victoria@gmail.com; Khodyrevskaya, Y. I.; Glushkova, T. V.; Antonova, L. V.; Kudryavtseva, Y. A.; Barbarash, O. L.; Barbarash, L. S. [Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo (Russian Federation)

    2015-10-27

    The development of tissue-engineered small-diameter vascular grafts is an urgent issue in cardiovascular surgery. In this study, we assessed how the incorporation of the vascular endothelial growth factor (VEGF) affects morphological and mechanical properties of polycaprolactone (PCL) vascular grafts along with its release kinetics. Vascular grafts were prepared using two-phase electrospinning. In pursuing our aims, we performed scanning electron microscopy, mechanical testing, and enzyme-linked immunosorbent assay. Our results demonstrated the preservation of a highly porous structure and improvement of PCL/VEGF scaffold mechanical properties as compared to PCL grafts. A prolonged VEGF release testifies the use of this construct as a scaffold for tissue-engineered vascular grafts.

  18. 3D physical modeling of anisotropic grain growth at high temperature in local strong magnetic force field

    Directory of Open Access Journals (Sweden)

    Eric Beaugnon

    2008-01-01

    Full Text Available A new mechanism based on the effect of local magnetic forces on diffusing ions around a growing ferromagnetic precipitate is proposed. A 3D simulation based only on physical parameters is undertaken in which main assumption is of interface limited growth controlled by the effect of both curvature and local magnetic field distortion. Although usually neglected in magnetic field effect mechanisms, it is shown that these local magnetic forces acting on a single paramagnetic ion can change markedly affect the growth process and induce strong shape anisotropy.

  19. Fall growth, nutritive value, and estimation of total digestible nutrients for cereal-grain forages in the north-central United States.

    Science.gov (United States)

    Coblentz, W K; Walgenbach, R P

    2010-01-01

    Throughout the Southern Great Plains, wheat is managed frequently as a dual-purpose crop, but this production paradigm is not necessarily applicable throughout other regions of the United States, and a wider array of management options can be considered for forage-only uses of cereal grains. Our objectives were to assess the fall-growth potential of wheat (Triticum aestivum L.), triticale (X Triticosecale Wittmack), and oat (Avena sativa L.) cultivars in Wisconsin, and then to further evaluate and compare the fiber composition and TDN of these fall-grown forages. For 2006, yields of DM for all cultivars increased quadratically (P or = 0.072), including forage-type oat. Although TDN estimates generally were relatively static across harvest dates, the concentrations of truly digestible components constituting the total TDN pool were quite fluid. Generally, reductions of truly digestible CP were offset by increases in truly digestible nonfiber carbohydrate, truly digestible fiber, or both. The relatively stable energy densities for cereal-grain cultivars observed across harvest dates suggest that a broad window of opportunity exists for usage, including a single harvest as silage.

  20. Preparation, Characterization, and Bioactivity of Chitosan Microspheres Containing Basic Fibroblast Growth Factor

    Directory of Open Access Journals (Sweden)

    Bo Lv

    2014-01-01

    Full Text Available The aim of this study is to evaluate, prepare, and characterize bioactivity of chitosan microspheres loaded with bFGF for providing sustained release of bFGF. Porous chitosan microspheres were prepared by freeze-drying process based on the interaction between chitosan and tripolyphosphate (TPP. The bFGF-loaded chitosan microspheres were well interconnected and have a narrow size distribution, spherical shape, and positive surface charges. The bFGF-loading capacity and encapsulation efficiency were 7.57 mg/g and 95.1%, respectively. Results of in vitro release showed that the extent of release was 82.1% at Day 25. Schwann cells were used as an in vitro model for cell response to bFGF and bFGF-loaded chitosan microspheres. Results indicated that the number, cell viability, and percentage of cells G2/M+S phase in the bFGF groups are higher than those in the bFGF-loaded chitosan microspheres groups before culturing for 2 days. However, the number, cell viability, and percent of cells G2/M+S phase in the bFGF-loaded chitosan microspheres groups are significantly higher than those in the bFGF groups after culture for 4 and 8 days. These findings indicated that bFGF-loaded chitosan microspheres may help to decrease the release of bFGF and provide a suitable three-dimensional environment for cell growth and proliferation.

  1. [Preparation and Determination of Insulin-like Growth Factor I in Deer Antler, Heart and Blood].

    Science.gov (United States)

    Chen, Fan-bo; Yin, Jian-yuan; Liu, Jing-yan; Yang, Yu-xia; Sun, Dan-dan; Liu, Ji-hua

    2014-12-01

    To optimize the method for preparation of the insulin-like growth factor I (IGF-I ) in deer antler, and to determine the IGF-I in deer antler, heart and blood. Ultrasonic extraction was used to extract IGF-I from different tissues of deer with ammonia-ammonium acetate buffer, followed by ultrafiltration and solid phase extraction to concentrate and purify the samples. At the same time, ethanol precipitation method was carried out in the purification of IGF-I ultrafiltratein deer antler, a parallel test proceeded and radio immune assay (RIA) was set to determine the IGF-I in deer antler, heart and blood. The IGF-I (60.8 ng/g) in deer antler by solid phase extraction was only existed in 30% methanol aqueous solution which was much higher than that (46.1 ng/g) by ethanol precipitation method. The quantities of IGF-I in deer antler, heart and blood were significantly different, it was 61.9 ng/g in antler and 21.9 ng/mL in blood, while there was no IGF-I tested in deer heart. Solid phase extraction is superior to ethanol precipitation method in preparing IGF-I in deer antler and it is clear that the IGF-I contained in deer antler is significantly higher than that in deer heart and blood, so it is the best choice to take IGF-I from deer antler.

  2. Discarded oranges and brewer's spent grains as promoting ingredients for microbial growth by submerged and solid state fermentation of agro-industrial waste mixtures.

    Science.gov (United States)

    Aggelopoulos, Theodoros; Bekatorou, Argyro; Pandey, Ashok; Kanellaki, Maria; Koutinas, Athanasios A

    2013-08-01

    The exploitation of various agro-industrial wastes for microbial cell mass production of Kluyveromyces marxianus, kefir, and Saccharomyces cerevisiae is reported in the present investigation. Specifically, the promotional effect of whole orange pulp on cell growth in mixtures consisting of cheese whey, molasses, and potato pulp in submerged fermentation processes was examined. A 2- to 3-fold increase of cell mass was observed in the presence of orange pulp. Likewise, the promotional effect of brewer's spent grains on cell growth in solid state fermentation of mixtures of whey, molasses, potato pulp, malt spent rootlets, and orange pulp was examined. The cell mass was increased by 3-fold for K. marxianus and 2-fold for S. cerevisiae in the presence of these substrates, proving their suitability for single-cell protein production without the need for extra nutrients. Cell growth kinetics were also studied by measurements of cell counts at various time intervals at different concentrations of added orange pulp. The protein content of the fermented substrates was increased substantially, indicating potential use of mixed agro-industrial wastes of negligible cost, as protein-enriched livestock feed, achieving at the same time creation of added value and waste minimization.

  3. Enhancement of trapped field in single grain Y-Ba-Cu-O bulk superconductors by a modified top-seeded melt-textured growth

    Science.gov (United States)

    Tang, Tian-wei; Wu, Dong-jie; Xu, Ke-Xi

    2016-08-01

    The modified top-seeded melt-textured growth technique for fabricating single grain Y-Ba-Cu-O (YBCO) bulk superconductors with high field-trapping ability by using modified precursor pellets was reported. The modified precursor pellets are composed of different precursor powders YBa2Cu3O{}7-δ (Y123) + x mol% Y2BaCuO5 (Y211) + 1 wt% CeO2 without any further chemical doping. The modified YBCO bulks up to 25 and 34 mm in diameter were successfully fabricated from the modified precursor pellets. Microstructural observation results showed that the modified YBCO bulk exhibited a homogeneous distribution of Y211 phase particles, which was qualitatively explained by the solute diffusion growth model in combination with the trapping/pushing theory. As a result, it is notable that the peak trapped field values of 0.91 T (maximum 0.96 T) and 1.2 T (maximum 1.28 T) at 77 K were achieved for 25 and 34 mm modified YBCO bulks, respectively. In a word, the results from present work are very helpful to understand the melt growth mechanism and to further improve the properties of YBCO bulk superconductors for practical applications.

  4. Infrared Spectroscopic Survey of the Quiescent Medium of Nearby Clouds: I. Ice Formation and Grain Growth in Lupus

    CERN Document Server

    Boogert, A C A; Knez, C; Öberg, K I; Mundy, L G; Pendleton, Y J; Tielens, A G G M; van Dishoeck, E F

    2013-01-01

    Infrared photometry and spectroscopy (1-25 um) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of the grains and the composition of the ices before they are incorporated into circumstellar envelopes and disks. H2O ices form at extinctions of Ak=0.25+/-0.07 mag (Av=2.1+/-0.6). Such a low ice formation threshold is consistent with the absence of nearby hot stars. Overall, the Lupus clouds are in an early chemical phase. The abundance of H2O ice (2.3+/-0.1*10^-5 relative to Nh) is typical for quiescent regions, but lower by a factor of 3-4 compared to dense envelopes of YSOs. The low solid CH3OH abundance (5 um) continuum extinction relative to Ak increases as a function of Ak. Most Lupus lines of sight are well fitted with empirically derived extinction curves corresponding to Rv~ 3.5 (Ak=0.71) and Rv~5.0 (Ak=1.47). For lines of sight with Ak>1.0 mag, the tau9.7/Ak ratio is a factor of 2 lower compared to the diffuse medium. Below 1.0 mag, values scatter be...

  5. Grain charging in protoplanetary discs

    CERN Document Server

    Ilgner, Martin

    2011-01-01

    Recent work identified a growth barrier for dust coagulation that originates in the electric repulsion between colliding particles. Depending on its charge state, dust material may have the potential to control key processes towards planet formation such as MHD (magnetohydrodynamic) turbulence and grain growth which are coupled in a two-way process. We quantify the grain charging at different stages of disc evolution and differentiate between two very extreme cases: compact spherical grains and aggregates with fractal dimension D_f = 2. Applying a simple chemical network that accounts for collisional charging of grains, we provide a semi-analytical solution. This allowed us to calculate the equilibrium population of grain charges and the ionisation fraction efficiently. The grain charging was evaluated for different dynamical environments ranging from static to non-stationary disc configurations. The results show that the adsorption/desorption of neutral gas-phase heavy metals, such as magnesium, effects the ...

  6. 五氧化二铌与二氧化硅作用下氧化铝晶粒的各向异性生长%ANISOTROPIC GRAIN GROWTH OF ALUMINA BY SYNERGISTIC EFFECTS OF NIOBIUM PENTOXIDE AND SILICON DIOXIDE

    Institute of Scientific and Technical Information of China (English)

    尹贻彬; 刘于昌; 蒲锡鹏; 邵鑫; 李文智; 赵利民

    2009-01-01

    研究了少量SiO2和Nb2O5掺杂对α-氧化铝晶粒生长的影响.单一掺杂1 500℃煅烧2h的样品均表现为晶粒的等轴状,且铌掺杂明显促进了氧化铝晶粒的生长.SiO2与Nb2O5的共掺杂则导致晶粒各向异性优势生长.高分辨透射电镜照片表明:在一些晶粒晶界出现0.8~4nm的无定形层,晶界处的液相同样影响晶界能,从而诱导各向异性生长.结果表明:在固定铌含量的基础上,少量二氧化硅使材料的断裂韧度提高42%,抗弯强度提高约80%.%Grain growth caused by doping alpha-alumina with small amounts of silicon dioxide and niobium penroxide added singly or together was investigated in contrast to undoped alumina. When they were sintered at 1500 ℃ for 2 h, the alumina grain for singly doped specimen is equiaxed, and the niobium promotes excessive the grain growth of alumina. But the codoped specimen exhibited anisotropic grain growth and the volume is very large. High resolution transmission electron microscope photograph reveals that a thin amorphous layer (0.8-4 nm) is presented at some grain boundaries. Liquid phase may affect the energy of the grain boundary and induces anisotropic grain growth. The research results also show that when the niobium content is constant, the fracture toughness is enhanced by 42% and the bending strength is increased by 80% via adjusting the silicon contents.

  7. GRAIN GROWTH IN THE CIRCUMSTELLAR DISKS OF THE YOUNG STARS CY Tau AND DoAr 25

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, Laura M.; Chandler, Claire J. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Isella, Andrea [Rice University, 6100 Main Street, Houston, TX 77005 (United States); Carpenter, John M.; Sargent, Anneila I. [California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 (United States); Andrews, Sean M.; Ricci, Luca [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Calvet, Nuria [University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Corder, Stuartt A. [Joint ALMA Observatory, Av. Alonso de Córdova 3107, Vitacura, Santiago (Chile); Deller, Adam T. [The Netherlands Institute for Radio Astronomy (ASTRON), 7990-AA Dwingeloo (Netherlands); Dullemond, Cornelis P. [Heidelberg University, Center for Astronomy, Albert Ueberle Str 2, Heidelberg (Germany); Greaves, Jane S. [University of St. Andrews, Physics and Astronomy, North Haugh, St. Andrews KY16 9SS (United Kingdom); Harris, Robert J. [University of Illinois, 1002 West Green St., Urbana, IL 61801 (United States); Henning, Thomas; Linz, Hendrik [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Kwon, Woojin [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Lazio, Joseph [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91106 (United States); Mundy, Lee G.; Storm, Shaye [University of Maryland, College Park, MD 20742 (United States); Tazzari, Marco [European Southern Observatory, Karl Schwarzschild str. 2, D-85748 Garching (Germany); and others

    2015-11-01

    We present new results from the Disks@EVLA program for two young stars: CY Tau and DoAr 25. We trace continuum emission arising from their circusmtellar disks from spatially resolved observations, down to tens of AU scales, at λ = 0.9, 2.8, 8.0, 9.8 mm for DoAr 25 and at λ = 1.3, 2.8, 7.1 mm for CY Tau. Additionally, we constrain the amount of emission whose origin is different from thermal dust emission from 5 cm observations. Directly from interferometric data, we find that observations at 7 mm and 1 cm trace emission from a compact disk while millimeter-wave observations trace an extended disk structure. From a physical disk model, where we characterize the disk structure of CY Tau and DoAr 25 at wavelengths shorter than 5 cm, we find that (1) dust continuum emission is optically thin at the observed wavelengths and over the spatial scales studied, (2) a constant value of the dust opacity is not warranted by our observations, and (3) a high-significance radial gradient of the dust opacity spectral index, β, is consistent with the observed dust emission in both disks, with low-β in the inner disk and high-β in the outer disk. Assuming that changes in dust properties arise solely due to changes in the maximum particle size (a{sub max}), we constrain radial variations of a{sub max} in both disks, from cm-sized particles in the inner disk (R < 40 AU) to millimeter sizes in the outer disk (R > 80 AU). These observational constraints agree with theoretical predictions of the radial-drift barrier, however, fragmentation of dust grains could explain our a{sub max}(R) constraints if these disks have lower turbulence and/or if dust can survive high-velocity collisions.

  8. Route and Regulation of Zinc, Cadmium, and Iron Transport in Rice Plants (Oryza sativa L. during Vegetative Growth and Grain Filling: Metal Transporters, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification

    Directory of Open Access Journals (Sweden)

    Tadakatsu Yoneyama

    2015-08-01

    Full Text Available Zinc (Zn and iron (Fe are essential but are sometimes deficient in humans, while cadmium (Cd is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal transport and accumulation in rice plants by examining metal speciation, metal transporters, and the xylem-to-phloem transport system. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem transport system operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2′-deoxymugineic acid are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake transporter and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot transport, respectively, resulting in a reduction of grain Cd accumulation.

  9. Route and Regulation of Zinc, Cadmium, and Iron Transport in Rice Plants (Oryza sativa L.) during Vegetative Growth and Grain Filling: Metal Transporters, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification.

    Science.gov (United States)

    Yoneyama, Tadakatsu; Ishikawa, Satoru; Fujimaki, Shu

    2015-08-13

    Zinc (Zn) and iron (Fe) are essential but are sometimes deficient in humans, while cadmium (Cd) is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal transport and accumulation in rice plants by examining metal speciation, metal transporters, and the xylem-to-phloem transport system. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem transport system operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2'-deoxymugineic acid) are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake transporter and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot transport, respectively, resulting in a reduction of grain Cd accumulation.

  10. Effects of using ground redberry juniper and dried distillers grains with solubles in lamb feedlot diets: growth, blood serum, fecal, and wool characteristics.

    Science.gov (United States)

    Whitney, T R; Lupton, C J; Muir, J P; Adams, R P; Stewart, W C

    2014-03-01

    Effects of using ground redberry juniper and dried distillers grains with solubles (DDGS) in Rambouillet lamb (n = 45) feedlot diets on growth, blood serum, fecal, and wool characteristics were evaluated. In a randomized design study with 2 feeding periods (Period 1 = 64% concentrate diet, 35 d; Period 2 = 85% concentrate diet, 56 d), lambs were individually fed 5 isonitrogenous diets: a control diet (CNTL) that contained oat hay but not DDGS or juniper or DDGS-based diets in which 0 (0JUN), 33 (33JUN), 66 (66JUN), or 100% (100JUN) of the oat hay was replaced by juniper. During Period 1, lambs fed CNTL had greater (P diets. Lamb DMI, ADG, and G:F quadratically increased (P diets. During Period 2, lambs fed CNTL had greater (P diets, but ADG was similar (P > 0.41). Compared to 0JUN, lambs fed CNTL had similar (P = 0.12) G:F and tended to have less G:F (P = 0.07) than lambs fed DDGS-based diets. Among lambs fed DDGS-based diets, DMI was similar (P > 0.19), ADG increased linearly (P = 0.03), and G:F tended to decrease quadratically (P = 0.06) as juniper increased in the diet. Serum IGF-1, serum urea N (SUN), and fecal N were greater (P 0.13) for lambs fed CNTL vs. lambs fed DDGS-based diets (CNTL). Within lambs fed DDGS-based diets, SUN increased quadratically (P = 0.01) and fecal N increased linearly (P = 0.004), which can partially be attributed to increased dietary urea and condensed tannin intake. Most wool characteristics were not affected, but wool growth per kilogram of BW decreased quadratically (P = 0.04) as percentage of juniper increased in the DDGS-based diets. When evaluating the entire 91-d feeding trial, results indicated that replacing all of the ground oat hay with ground juniper leaves and stems in lamb growing and finishing diets is not detrimental to animal performance and that DDGS-based diets can reduce total feedlot costs, as compared to sorghum grain and cottonseed meal-based diets. However, compared to using juniper or oat hay as the sole

  11. The influence of slow cooling on Y211 size and content in single-grain YBCO bulk superconductor through the infiltration-growth process

    Science.gov (United States)

    Ouerghi, A.; Moutalbi, N.; Noudem, J. G.; M'chirgui, A.

    2017-03-01

    Highly textured YBa2Cu3O7-δ (Y123) superconductors were produced using modified Textured Top Seeded Infiltration Growth (TSIG) process. The liquid source is made of only Y123 powder whereas the solid source is composed of Y2BaCuO5 (Y211) powder. We aim to control the amount of liquid that infiltrates the solid pellet, which in turn controls the final amount of Y2BaCuO5 particles in Y123 matrix. The effect of the slow cooling kinetics on sample morphology, on grain growth and on final microstructure was too investigated. It is shown that appropriate slow cooling time may also contribute to the control of the amount of Y211 inclusions in the final structure of Y123 bulk. We report herein the Y211 particle size and density distribution in the whole Y123 matrix. The present work proves that finest Y211 particles locate under the seed and that their size and density increase with distance from the seed.

  12. The effect of resolidification on preform optimized infiltration growth processed (Y, Nd, Sm, Gd)BCO, multi-grain bulk superconductor

    Science.gov (United States)

    Pavan Kumar Naik, S.; Seshu Bai, V.

    2017-01-01

    Controlling the microstructure of superconductors by incorporating the flux pinning centers and reducing the macro-defects to improve high field performance is the topic of recent research. In continuation, the preform optimized infiltration growth (POIG) processed YBa2Cu3O7-δ (YBCO) system, Y-site substituted with three mixed RE (Nd, Sm, Gd) elements is investigated. 20 wt.% of (Nd, Sm, Gd)2BaCuO5 were mixed with Y2BaCuO5 and POIG processed in reduced oxygen atmosphere to obtain YNSG superconductor. No seed is employed for crystal growth; hence the processed samples are multi-grained. Microstructural and compositional investigations on YNSG revealed the presence of different phases in the matrix as well as in precipitates which are of the order of submicron to 4 μm. A large fraction of macro-defects (∼6% of porosity) was observed in the YNSG sample. For reducing the unwanted macro-defects and refine the non-superconducting precipitates, processed YNSG sample is pressed and resolidified (by infiltrating the liquid phases once again) in an argon atmosphere and the structural, microstructural, elemental and superconducting properties are compared with YNSG and undoped samples. Due to spatial scatter in superconducting critical temperatures, caused by the distribution of different REBCO unit cells in YBCO, superconducting transition curve is sharp in YNSG, whereas the resolidified sample showed the broad transition due to solidified liquid phases.

  13. Texture control and growth mechanism of WSe2 film prepared by rapid selenization of W film

    Science.gov (United States)

    Li, Hongchao; Gao, Di; Li, Kun; Pang, Mengde; Xie, Senlin; Liu, Rutie; Zou, Jianpeng

    2017-02-01

    The tungsten diselenide (WSe2) films with different orientation present unique properties suitable for specific applications, such as WSe2 with a C-axis⊥substrate for optoelectronics and WSe2 with a C-axis // substrate for electrocatalysts. Orientation control of WSe2 is essential for realizing the practical applications. In this letter, a WSe2 film has been prepared via rapid selenization of a magnetron-sputtered tungsten (W) film. The influence of the magnetron-sputtered W film on WSe2 film growth was studied systematically. Scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy were used to evaluate the morphology, microstructure and phase composition of the W and WSe2 films. The substrate temperature has a significant effect on the W film phase composition, but little effect on the WSe2 film orientation. The WSe2 orientation can be controlled by changing the W film microstructure. A dense W film that is deposited at low pressure is conducive to the formation of WSe2 with a C-axis⊥substrate, whereas a porous W film deposited at high pressure favors the formation of WSe2 with a C-axis // substrate. A growth model for the WSe2 film with different texture has been proposed based on the experimental results. The direction of selenium (Se) vapor diffusion differs at the top and side surfaces. This is a key factor for the preparation of anisotropic WSe2 films. Highly oriented WSe2 films with a C-axis⊥substrate grow from the dense W film deposited at low pressure because Se vapor can only diffuse into the W film from the top surface where it is converted into selenide. Highly oriented WSe2 with a C-axis // substrate can be achieved for the porous W film that is deposited at high pressure because the nanopores provide a fast transmission tunnel for Se vapor diffusion. These findings will contribute to the controlled fabrication of WSe2 film and provide a theoretical basis for its application.

  14. Oxide Particle Growth During Friction Stir Welding of Fine Grain MA956 Oxide Dispersion-Strengthened Steel

    Science.gov (United States)

    Baker, Brad W.; Knipling, Keith E.; Brewer, Luke N.

    2017-03-01

    Friction stir welding of an aluminum-containing oxide dispersion-strengthened steel causes significant oxide particle growth visible at both the nano- and microscales. Quantitative stereology of scanning electron images, small-angle X-ray scattering, energy-dispersive X-ray spectroscopy, and atom-probe tomography is used to quantify the degree of particle coarsening as a function of welding parameters. Results show the dispersed oxides are significantly coarsened in the stir zone due to a proposed combination of agglomeration, Ostwald ripening, and phase transformation within the Al2O3-Y2O3 system. This oxide particle coarsening effectively removes all strengthening contribution of the original oxide particles, as confirmed by uniaxial tensile tests and microhardness measurements.

  15. Oxide Particle Growth During Friction Stir Welding of Fine Grain MA956 Oxide Dispersion-Strengthened Steel

    Science.gov (United States)

    Baker, Brad W.; Knipling, Keith E.; Brewer, Luke N.

    2017-01-01

    Friction stir welding of an aluminum-containing oxide dispersion-strengthened steel causes significant oxide particle growth visible at both the nano- and microscales. Quantitative stereology of scanning electron images, small-angle X-ray scattering, energy-dispersive X-ray spectroscopy, and atom-probe tomography is used to quantify the degree of particle coarsening as a function of welding parameters. Results show the dispersed oxides are significantly coarsened in the stir zone due to a proposed combination of agglomeration, Ostwald ripening, and phase transformation within the Al2O3-Y2O3 system. This oxide particle coarsening effectively removes all strengthening contribution of the original oxide particles, as confirmed by uniaxial tensile tests and microhardness measurements.

  16. Preparation of soluble isotopically labeled human growth hormone produced in Escherichia coli.

    Science.gov (United States)

    Lee, Jin-Hee; Jeong, Ji-Seon; Kim, Sook-Kyung; Song, Jimyeong; Lee, Ji Youn; Baek, Soyun; Choi, Jun-Hyuk

    2016-11-01

    Isotopically labeled proteins have been used as internal standards for mass spectrometry (MS)-based absolute protein quantification. Although this approach can provide highly accurate analyses of proteins of interest within a complex mixture, one of the major limitations of this method is the difficulty in preparing uniformly labeled standards. Human growth hormone (hGH) is one of the most important hormones that circulate throughout the body, and its measurement is primarily of interest in the diagnosis and treatment of growth disorders. In order to provide a useful internal standard for MS-based hGH measurement, we describe an efficient strategy to produce a potentially valuable, stable isotope-labeled hGH with high purity and yield. The strategy involves the following steps: solubilization of hGH under labeling conditions, detection of stable isotope incorporation, large-scale purification, analysis of the labeled protein, and assessment of the labeling efficiency. We show that the yield of soluble hGH under selective isotopic labeling conditions can be greatly increased by optimizing protein expression and extraction. Our efficient method for generating isotopically labeled hGH does not influence the structural integrity of hGH. Finally, we assessed the efficiency of stable isotope labeling at the intact protein level, and the result was further verified by amino acid analysis. These results clearly indicate that our labeling approach allows an almost complete incorporation of (13)C6(15)N4-arginine into the hGH expressed in E.coli without detectable isotope scrambling.

  17. Influence of grain growth on the high-frequency behaviour of ferromagnetic Fe-Co-(M)-N (M=Ta, Hf) nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, K. [Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut fuer Material for schung I, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)], E-mail: klaus.seemann@imf.fzk.de; Leiste, H. [Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut fuer Material for schung I, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

    2009-04-15

    The CMOS compatible ferromagnetic Fe-Co-(M)-N (M=Ta, Hf) films were investigated with regard to their grain size-dependent frequency behaviour. Predominantly Fe{sub 33}Co{sub 40}Ta{sub 10}N{sub 17} films were deposited by reactive r.f. magnetron sputtering. These films were compared to Fe{sub 36}Co{sub 44}Hf{sub 9}N{sub 11} films. In order to induce an in-plane uniaxial anisotropy H{sub u} as well as to investigate the grain growth behaviour, the films were annealed in a static magnetic field. The in-plane uniaxial anisotropy field of around 4 mT as well as a good soft magnetic behaviour with a saturation polarisation of approximately 1.2-1.4 T could be observed after heat treatment. Ferromagnetic resonance frequencies (FMR) of approximately up to 2.4 GHz could be achieved according to the Kittel theory. Depending on the heat treatment, high-frequency losses through energy dissipation was made conspicuous by means of the full-width at half-maximum (FWHM) {delta}f{sub eff} of the imaginary part of the frequency-dependent permeability which was between 0.4 and 1 GHz. This FWHM was basically discussed in terms of two-magnon scattering theories, in combination with the Herzer random anisotropy model. In order to correlate the resonance line broadening with a phenomenological damping parameter {alpha}{sub eff}, which ranged from about 0.0125 to 0.028, the modified Landau-Lifschitz-Gilbert equation was used to fit and describe the permeability spectra of the ferromagnetic films.

  18. Platelet-rich plasma preparation using three devices : Implications for platelet activation and platelet growth factor release

    NARCIS (Netherlands)

    Everts, Peter A. M.; Mahoney, Christine Brown; Hoffmann, Johannes J. M. L.; Schonberger, Jacques P. A. M.; Box, Henk A. M.; Van Zundert, Andre; Knape, Johannes T. A.

    2006-01-01

    Background: In this study, three commercial systems for the preparation of platelet-rich plasma (PRP) were compared and platelet growth factors release was measured. Methods: Ten healthy volunteers donated whole blood that was fractionated by a blood cell separator, and a table-top centrifuge to pre

  19. Absorption kinetics of two highly concentrated preparations of growth hormone: 12 IU/ml compared to 56 IU/ml

    DEFF Research Database (Denmark)

    Laursen, Torben; Susgaard, Søren; Jensen, Flemming Steen;

    1994-01-01

    in the interval 0.8-1.25, implying that the two preparations are bioequivalent. Neither AUC (P = 0.90), Cmax (p = 0.47) or Tmax (P = 0.86) for the two formulations of growth hormone were significantly different. Similar levels of serum IGF-I, IGFBP-3, insulin and blood glucose were obtained.(ABSTRACT TRUNCATED...

  20. Growth characteristics of MoS2 coatings prepared by unbalanced bipolar DC magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    WANG Ji-hui; XIA Yang; E.Wieers; L.M.Stals; J.P.Celis

    2005-01-01

    MoS2 coatings were prepared by unbalanced bipolar DC magnetron sputtering under different argon pressures and for different deposition times, and the structure and morphology of MoS2 coatings were determined and observed respectively by X-ray diffractometry and scanning electron microscopy. The results show that at lower argon pressures of 0.15Pa and 0.40Pa, MoS2 coatings are formed with the (002) basal plane parallel to the surface, whereas the coating deposited at the argon pressure above 0.60Pa has the (002) basal plane perpendicular to the surface. Two stages can be classified for the formation of MoS2 coating. At the initial stage of coating formation, the (002) basal plane with S-Mo-S layer structure grows on the substrate whatever the argon pressure is. And then the coating under 0.40Pa argon pressure still grows with (002) laminate structure, but the coatings under 0.88Pa and 1.60Pa argon pressures turn to grow with the mixed basal and edge orientations. The morphology and structure of MoS2 coatings are highly related to their growth rate and the energy of sputtered particles.

  1. Evaluation of commercially available enzymes, probiotics, or yeast on apparent total-tract nutrient digestion and growth in nursery and finishing pigs fed diets containing corn dried distillers grains with solubles

    Science.gov (United States)

    The ability of enzymes, direct fed microbials, or yeast to enhance nutrient utilization or growth performance in nursery or finishing pigs fed diets containing increased levels of corn fiber from dried distillers grains with solubles (DDGS) is largely unknown. Ten commercially available feed additiv...

  2. Spark Plasma Sintering of high-strength ultrafine-grained tungsten carbide

    Science.gov (United States)

    Nokhrin, A. V.; Chuvil'deev, V. N.; Blagoveshchenskiy, Yu V.; Boldin, M. S.; Sakharov, N. V.; Isaeva, N. V.; Popov, A. A.; Lantcev, E. A.; Belkin, O. A.; Smirnova, E. S.

    2017-07-01

    The paper dwells on the research conducted into high-rate consolidation of pure tungsten carbide nanopowders using the Spark Plasma Sintering. Studies included the effect that the original size of WC nanoparticles and their preparation modes have on density, structure parameters, and mechanical properties of tungsten carbide. It has been found that materials that show abnormal grain growth during sintering have lower values of sintering activation energy as compared to materials the structure of which is more stable during high-rate heating. A qualitative model is proposed that explains this effect through the dependence of the grain boundary diffusion coefficient on the grain boundary migration rate.

  3. Products deriving from microbial fermentation are linked to insulinaemic response in pigs fed breads prepared from whole-wheat grain and wheat and rye ingredients

    DEFF Research Database (Denmark)

    Theil, Peter Kappel; Jørgensen, Henry Johs. Høgh; Serena, Anja;

    2011-01-01

    The effects of wheat and rye breads made from whole-wheat grain (WWG), wheat aleurone flour (WAF) or rye aleurone flour (RAF) on net portal absorption of carbohydrate-derived nutrients (glucose, SCFA and lactate) and apparent insulin secretion were studied in a model experiment with catheterised...

  4. Frequency of wet brewers grains supplementation during late gestation of beef cows and its effects on offspring postnatal growth and immunity.

    Science.gov (United States)

    Moriel, P; Artioli, L F A; Piccolo, M B; Marques, R S; Poore, M H; Cooke, R F

    2016-06-01

    Our objectives were to evaluate postnatal growth and measurements of innate and humoral immunity of beef calves born to dams fed wet brewers grains (WBG) daily or 3 times weekly during late gestation. On d 0 (approximately 60 d before calving), 28 multiparous, spring-calving Angus cows (BW = 578 ± 19 kg; age = 4.7 ± 0.65 yr; BCS = 7.0 ± 0.18) were stratified by sire, age, BW, and BCS and then randomly allocated into 1 of 14 drylot pens (2 cows/pen; 18 by 3 m; 27 m/cow). Cows were offered ground tall fescue hay ad libitum and received similar weekly WBG supplementation (DMI = 0.5% of BW multiplied by 7 d). Treatments were randomly assigned to pens (7 pens/treatment) and consisted of cows receiving WBG supplementation daily (S7; weekly DMI of WBG divided by 7 d) or 3 times weekly (S3; weekly DMI of WBG divided by 3 d; Mondays, Wednesdays, and Fridays) from d 0 until calving. Cow-calf pairs were managed as a single group on tall fescue pastures from calving to weaning (d 226). Calves were immediately submitted to a preconditioning period from d 226 to 266 and vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea virus, , and on d 231 and 245. Decreasing the frequency of WBG supplementation did not impact ( ≥ 0.21) precalving intake of total DM, CP, and TDN; BW and BCS change; overall plasma cortisol concentrations; and postcalving growth and pregnancy rate of cows. Overall plasma concentrations of glucose and insulin did not differ ( ≥ 0.28) between S3 and S7 cows, whereas S3 cows had greater ( = 0.002) plasma glucose concentrations and tended ( = 0.06) to have greater plasma insulin concentrations on days they were not fed WBG vs. days of WBG supplementation. Calf plasma concentrations of haptoglobin and cortisol at birth but not serum IgG ( = 0.63) tended ( = 0.10) to be greater for S3 vs. S7 calves. However, additional calf growth and immunity variables obtained during pre- and postweaning phases did not differ between S3 and S7 calves

  5. Preparation of Graphene Oxide and Its Mechanism in Promoting Tomato Roots Growth.

    Science.gov (United States)

    Jiao, Jingzhi; Cheng, Fan; Zhang, Xuekun; Xie, Lingli; Li, Zhiyang; Yuan, Chengfei; Xu, Benbo; Zhang, Liming

    2016-04-01

    Graphene oxide is a new kind of nanomaterial. The graphene oxide was prepared and its quality detected by atomic force microscopy (AFM) and transmission electron microscopy (TEM), for better understanding of effects of the nanomaterial on plants. Wild type. (WT) tomato (Solanum lycopersicum) germplasm 'New Yorker' and corresponding transgenic plants (Prd29A::LeNCED1) were treated with prepared graphene oxide. 9-cis-epoxycarotenoid dioxygenase (NCED) is a key gene for ABA biosynthesis and overexpression of the NCED resulted in ABA accumulation and higher drought tolerance. Seminal root length in the WT tomato was longer than that in the control samples when the seedlings were treated with 20 mg/L graphene oxide for 15 days. In contrast, the same treatment resulted in shorter seminal root length in the transgenic plants compared with control samples. The graphene oxide treatments led to lower Superoxide Dismutase (SOD), Peroxidase (POD), Catalase (CAT) activity and Malondialdehyde (MDA) content in the WT and transgenic plants. 20 mg/L graphene oxide treatment also affected the transcript levels of IAA7, IAA4 and IAA10 but the effect on the wild type and corresponding transgenic plants was different. IAA4 transcription level decreased both in the WT and Prd29A::LeNCED1 transgenic plants while the IAA7 transcription level decreased in the transgenic plants and increased in the WT tomato. The IAA10 transcription level decreased in the WT tomato and increased in the Prd29A::LeNCED1 transgenic plants. Graphene oxide treatments resulted in higher transcription level of ABCG25 and ABCG40 in the WT plants but had no significant effect on transgenic plants. The transcription level of NCED in the WT and Prd29A::LeNCED1 transgenic plants treated with graphene oxide increased significantly, however, it was higher in the transgenic plants than in the WT tomato after 15 d treatment, indicating that the graphene oxide activated the rd29A promoter as does drought and salt. The HD

  6. Role of specific components from commercial inactive dry yeast winemaking preparations on the growth of wine lactic acid bacteria.

    Science.gov (United States)

    Andújar-Ortiz, Inmaculada; Pozo-Bayón, Maria Angeles; García-Ruiz, Almudena; Moreno-Arribas, M Victoria

    2010-07-28

    The role of specific components from inactive dry yeast preparations widely used in winemaking on the growth of three representative wine lactic acid bacteria (Oenococcus oeni, Lactobacillus hilgardii and Pediococcus pentosaceus) has been studied. A pressure liquid extraction technique using solvents of different polarity was employed to obtain extracts with different chemical composition from the inactive dry yeast preparations. Each of the extracts was assayed against the three lactic acid bacteria. Important differences in the effect of the extracts on the growth of the bacteria were observed, which depended on the solvent employed during the extraction, on the type of commercial preparations and on the lactic acid bacteria species. The extracts that exhibited the most different activity were chemically characterized in amino acids, free monosaccharides, monosaccharides from polysaccharides, fatty acids and volatile compounds. In general, specific amino acids and monosaccharides were related to a stimulating effect whereas fatty acid composition and likely some volatile compounds seemed to show an inhibitory effect on the growth of the lactic acid bacteria. These results may provide novel and useful information in trying to obtain better and more specific formulations of winemaking inactive dry yeast preparations.

  7. Growth and yield of two grain crops on sites former covered with euca-lypt plantations in Koga Watershed, northwestern Ethiopia

    Institute of Scientific and Technical Information of China (English)

    Desalegn Tadele; Demel Teketay

    2014-01-01

    Farmers in the highlands of Ethiopia often plant Eucalyptus on their farmlands. However, growing Eucalyptus, especially on farm-lands suitable for crop production has become a great concern due to its alleged long-term site effects. Our study was conducted at Koga water-shed, Mecha District, northwestern Ethiopia to investigate whether crop-lands afforested with Eucalyptus camaldulensis Dehnh. can be restored for annual crop production after tree harvest. We compared growth and yield of two agricultural crops, barley (Hordeum vulgare L.) and finger millet (Eleusine coracana (L.) Gaertn.), grown in clear-felled stands of E. camaldulensis and continuously cultivated croplands at twelve paired farmlands under a conventional farming system. Plant height and dry matter production were evaluated as indices of crop growth, while grain weight was evaluated as an index of crop yield. Crop growth and yield measurements averaged over all farmlands differed between land-use types. For both crops, plants grown on clear-felled stands were taller than on croplands. Dry matter production and yield were also significantly greater in crops cultivated on clear-felled stands. Cropland aboveground and belowground dry matter productions were lower by 31.8 and 25.4%for barley and 32.8%and 37%for finger millet, respectively. Clear-felled stands gave an average yield of 2.91 t⋅ha-1 for barley and 3.27 t⋅ha-1 for finger millet while cropland gave a yield of 1.97 and 2.31 t⋅ha-1 for barley and finger millet, respectively. Farmers also responded that farm plots on former eucalypt plantations showed greater crop growth and yield than did continuously cultivated croplands. Farmers perceived that Eucalyptus plantations improved soil fertility and they preferred clear-felled stands for crop production and wished to plant Eucalyptus on their farmlands. Our results suggest that conversion of agricultural lands to Eucalyptus plantations can increase post-felling yields of cereal crops.

  8. Effects of local structure on helium bubble growth in bulk and at grain boundaries of bcc iron: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Li [Univ. of Electronic Science and Technology of China, Chengdu (China); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gao, Fei [Univ. of Michigan, Ann Arbor, MI (United States); Kurtz, Richard J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zu, Xiaotao [Univ. of Electronic Science and Technology of China, Chengdu (China); Peng, S. M. [China Academy of Engineering Physics, Mianyang (China); Long, X. G. [China Academy of Engineering Physics, Mianyang (China); Zhou, X. S. [China Academy of Engineering Physics, Mianyang (China)

    2015-07-15

    The nucleation and growth of helium (He) bubbles in the bulk and at Σ3 <110> {112} and Σ73b <110> {661} grain boundaries (GBs) in bcc iron have been investigated using molecular dynamics simulations. The results show that a 1/2 <111> {111} dislocation loop is formed with the sequential collection of <111> interstitial crowdions at the periphery of the He cluster and is eventually emitted from the He cluster. Insertion of 45 He atoms into a He cluster leads to the formation of a 1/2 <111> dislocation loop in Σ3 GB. It is of interest to notice that the transition of a dislocation segment through the GB leads to the formation of a step at the GB plane following the loop formation, accounting for the formation of a residual GB defect. A 1/2 <111> loop, with a {110} habit plane, is emitted with further increase of the He bubble size in the Σ3 GB. In contrast, the sequential insertion of He atoms in Σ73b GB continuously emits self-interstitial atoms (SIAs), but these SIAs rearrange at the core of the inherent GB dislocation, instead of forming a dislocation loop, which leads the GB dislocation to propagate along the [1¯1¯ 1 2] direction. In the bulk and Σ3 GB, the He bubble exhibits three-dimensionally spherical shape, but it forms longitudinal shape along the dislocation line in the Σ73 GB, a shape commonly observed at GBs in experiments.

  9. Indications for Grain Growth and Mass Decrease in Cold Dust Disks around Classical T Tauri Stars in the MBM 12 Young Association

    Science.gov (United States)

    Hogerheijde, Michiel R.; Johnstone, Doug; Matsuyama, Isamu; Jayawardhana, Ray; Muzerolle, James

    2003-08-01

    We report the detection of continuum emission at λ=850 and 450 μm from disks around four classical T Tauri stars in the MBM 12 (L1457) young association. Using a simple model, we infer masses of 0.0014-0.012 Msolar for the disk of LkHα 263 ABC, 0.005-0.021 Msolar for S18 ABab, 0.03-0.18 Msolar for LkHα 264 A, and 0.023-0.23 Msolar for LkHα 262. The disk mass found for LkHα 263 ABC is consistent with the 0.0018 Msolar inferred from the scattered-light image of the edge-on disk around component C. Comparison to earlier 13CO line observations indicates CO depletion by up to a factor of 300 with respect to dark-cloud values. The spectral energy distributions (SEDs) suggest grain growth, possibly to sizes of a few hundred microns, but our spatially unresolved data cannot rule out opacity as an explanation for the SED shape. Our observations show that these T Tauri stars are still surrounded by significant reservoirs of cold material at an age of 1-5 Myr. We conclude that the observed differences in disk mass are likely explained by binary separation affecting the initial value. With available accretion rate estimates we find that our data are consistent with theoretical expectations for viscously evolving disks having decreased their masses by ~30%.

  10. Indications for grain growth and mass decrease in cold dust disks around Classical T Tauri stars in the MBM 12 young association

    CERN Document Server

    Hogerheijde, M R; Matsuyama, I; Jayawardhana, R; Muzerolle, J; Hogerheijde, Michiel R.; Johnstone, Doug; Matsuyama, Isamu; Jayawardhana, Ray; Muzerolle, James

    2003-01-01

    We report detection of continuum emission at 850 and 450 micron from disks around four Classical T Tauri stars in the MBM 12 (L1457) young association. Using a simple model we infer masses of 0.0014-0.012 M_sun for the disk of LkHa 263 ABC, 0.005-0.021 M_sun for S18 ABab, 0.03-0.18 M_sun for LkHa 264 A, and 0.023-0.23 M_sun for LkHa 262. The disk mass found for LkHa 263 ABC is consistent with the 0.0018 M_sun inferred from the scattered light image of the edge-on disk around component C. Comparison to earlier 13CO line observations indicates CO depletion by up to a factor 300 with respect to dark-cloud values. The spectral energy distributions (SED) suggest grain growth, possibly to sizes of a few hundred micron, but our spatially unresolved data cannot rule out opacity as an explanation for the SED shape. Our observations show that these T Tauri stars are still surrounded by significant reservoirs of cold material at an age of 1-5 Myr. We conclude that the observed differences in disk mass are likely explain...

  11. WO{sub 3} nanorods prepared by low-temperature seeded growth hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Chai Yan [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Abdul Razak, Khairunisak, E-mail: khairunisak@eng.usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lockman, Zainovia, E-mail: zainovia@eng.usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2014-03-05

    Highlights: • WO{sub 3} nanorods with 5–10 nm diameter were grown directly on seeded tungsten foil. • WO{sub 3} nanorods were successfully grown at low temperature of 80 °C. • WO{sub 3} nanorods were grown on the entire surface of the seed layer after 24 h. • Annealed nanorods showed better electrochromic properties than as-made nanorods. -- Abstract: This work describes the first tungsten oxide (WO{sub 3}) nanorods hydrothermally grown on W foil. WO{sub 3} nanorods were successfully grown at low hydrothermal temperature of 80 °C by seeded growth hydrothermal reaction. The seed layer was prepared by thermally oxidized the W foil at 400 °C for 0.5 h. This work discusses the effect of hydrothermal reaction and annealing period on the morphological, structural, and electrochromic properties of WO{sub 3} nanorods. Various hydrothermal reaction periods (8–24 h) were studied. Monoclinic WO{sub 3} nanorods with 5–10 nm diameter were obtained after hydrothermal reaction for 24 h. These 24 h WO{sub 3} nanorods were also annealed at 400 °C with varying dwelling periods (0.5–4 h). Electrochromic properties of WO{sub 3} nanorods in an acidic electrolyte were analyzed using cyclic voltammetry and UV–vis spectrophotometry. WO{sub 3} nanorods annealed at 400 °C for 1 h showed the highest charge capacity and the largest optical contrast among the 24 h WO{sub 3} films. The sample also showed good cycling stability without significant degradation. Based on the results, the reaction mechanism of WO{sub 3} nanorod formation on W foil was proposed.

  12. Decreasing the frequency and rate of wet brewers grains supplementation did not impact growth but reduced humoral immune response of preconditioning beef heifers.

    Science.gov (United States)

    Moriel, P; Piccolo, M B; Artioli, L F A; Poore, M H; Marques, R S; Cooke, R F

    2016-07-01

    This study evaluated growth and measurements of innate and humoral immunity of preconditioning beef heifers supplemented with wet brewers grains (WBG) at 2 supplementation rates and frequencies. At 14 d after weaning (d 0), Angus heifers ( = 36; 213 ± 2 kg BW and 254 ± 7 d of age) were stratified by BW and age and randomly assigned to 1 of 12 drylot pens (3 heifers/pen). Treatments were randomly assigned to pens, in a 2 × 2 factorial design, and consisted of heifers provided ground tall fescue hay ad libitum (55% TDN and 12% CP of DM) and supplemented with WBG (75% TDN and 36% CP of DM) either daily (7X) or 3 times weekly (3X; Monday, Wednesday, and Friday) at 0.5 or 1.0% of BW (DM basis) for 42 d. Heifers were vaccinated against infectious bovine rhinotracheitis (IBR), bovine viral diarrhea virus (BVDV), Mannheimia haemolytica, and Clostridium on d 14 and 28. Individual BW was measured before feeding on d 0 and 42 following 12 h of feed and water withdrawal. Blood samples were collected via jugular venipuncture 4 h after WBG supplementation on d 14, 15, 16, 17, 21, 28, 29, 30, 31, 35, and 42. Heifers fed WBG 3X had less hay DMI (2.6 ± 0.16 vs. 3.2 ± 0.16 kg/d; against BVDV-2 and IBR were greater for heifers fed WBG at 1.0% of BW vs. heifers fed WBG at 0.5% of BW (7.6 vs. 6.7 and 3.3 vs. 2.8 ± 0.19 log, respectively). In summary, decreasing WBG supplementation frequency (7 vs. 3 times weekly) or rate (1.0 vs. 0.5% of BW) for recently weaned beef heifers did not affect growth but decreased vaccine-induced antibody production against pathogens associated with bovine respiratory disease during a 42-d preconditioning period.

  13. Effect of yeast-derived products and distillers dried grains with solubles (DDGS) on growth performance and local innate immune response of broiler chickens challenged with Clostridium perfringens.

    Science.gov (United States)

    Alizadeh, M; Rogiewicz, A; McMillan, E; Rodriguez-Lecompte, J C; Patterson, R; Slominski, B A

    2016-06-01

    This study evaluated the effect of yeast-derived products on growth performance, gut lesion score, intestinal population of Clostridium perfringens, and local innate immunity of broiler chickens challenged with C. perfringens. One-day-old broiler chickens were randomly assigned to eight dietary treatments providing six replicate pens of 55 birds each per treatment. Dietary treatments consisted of Control diets without and with C. perfringens challenge, and diets containing bacitracin methylene disalicylate (BMD, 55 g/tonne), nucleotides (150 g/tonne), yeast cell wall (YCW, 300 g/tonne), and a commercial product Maxi-Gen Plus (1 kg/tonne) fed to chickens challenged with C. perfringens. Diets containing 10% distillers dried grains with solubles without and with C. perfringens challenge were also used. Birds were orally challenged with C. perfringens (10(8) colony-forming units (cfu)/bird) on day 14. On day 21, intestinal samples were collected for gene expression analysis. Pathogen challenge significantly (P intestinal lesion scores were observed for challenged birds except the BMD-containing diet. Over the entire trial (1-35 days), no difference in growth performance was observed except the BMD diet which improved FCR over the Control, challenged group. Birds receiving nucleotides showed increased expression of toll-like receptors and cytokines interleukin (IL)-4 and IL-18 compared to the Control, challenged group. Expression of macrophage mannose receptor and IL-18 was upregulated in birds receiving YCW. Increased expression of cytokines and receptors involved in innate immunity in broilers receiving nucleotides and YCW suggests the immunomodulatory properties of these products under pathogen challenge conditions.

  14. Effect of growth time on Ti-doped ZnO nanorods prepared by low-temperature chemical bath deposition

    Science.gov (United States)

    Bidier, Shaker A.; Hashim, M. R.; Al-Diabat, Ahmad M.; Bououdina, M.

    2017-04-01

    Ti-doped ZnO nanorod arrays were grown onto Si substrate using chemical bath deposition (CBD) method at 93 °C. To investigate the effect of time deposition on the morphological, and structural properties, four Ti-doped ZnO samples were prepared at various deposition periods of time (2, 3.5, 5, and 6.5 h). FESEM images displayed high-quality and uniform nanorods with a mean length strongly dependent upon deposition time; i.e. it increases for prolonged growth time. Additionally, EFTEM images reveal a strong erosion on the lateral side for the sample prepared for 6.5 h as compared to 5 h. This might be attributed to the dissolution reaction of ZnO with for prolonged growth time. XRD analysis confirms the formation of a hexagonal wurtzite-type structure for all samples with a preferred growth orientation along the c-axis direction. The (100) peak intensity was enhanced and then quenched, which might be the result of an erosion on the lateral side of nanorods as seen in EFTEM. This study confirms the important role of growth time on the morphological features of Ti-doped ZnO nanorods prepared using CBD.

  15. Contracts for Grain Biosecurity and Grain Quality

    OpenAIRE

    Abougamos, Hoda; White, Benedict; Sadler,Rohan

    2012-01-01

    The export of grain from Western Australia depends upon a grain supply network that takes grain from farm to port through Cooperative Bulk Handling receival and storage sites. The ability of the network to deliver pest free grain to the port and onto ship depends upon the quality of grain delivered by farmers and the efficacy of phosphine based fumigation in controlling stored grain pests. Phosphine fumigation is critical to the grain supply network because it is the cheapest effective fumiga...

  16. Prediction of HAZ grain size in welding of ultra fine grained steel with different parameters

    Institute of Scientific and Technical Information of China (English)

    Zhao Hongyun; Zhang Hongtao; Li Dongqing; Wang Guodong

    2010-01-01

    The temperature field and thermal cycling curve in the heat-affected zone during welding 400 MPa ultra fine grained steel by plasma arc were simulated using finite element method.The principle of grain growth kinetics was used to predict the grain size in the heat-affected zone under different welding parameters.The simulation results show that the growing tendency of HAZ grain could be controlled by adjusting the welding parameters,but the growth of HAZ grain could not be eliminated at all.The HAZ grain size became small with increasing of the cooling rate and added with increasing of welding current,arc voltage and welding speed.

  17. An ideal preparation for dermal regeneration: skin renewal growth factors, the growth factor composites from porcine platelets.

    Science.gov (United States)

    Wang, Kuo-Hsien; Wu, Yo-Ping Greg; Lo, Wen-Cheng

    2012-12-01

    The use of growth factor composites from platelets has been introduced to many areas of clinical applications and studies. With the richest source of growth factors (GFs), beneficial effects have been shown on tissue regeneration and wound healing. However, animal and clinical studies have revealed inconsistent outcomes with the use of platelet-derived growth factors (PDGFs), which were likely due to variations in the presence and concentrations of GFs between various sources. Autologous PDGFs are considered to be safer, but they are limited by the feasibility of large-scale production to be used extensively in the acute phase, greater surface area, or general cosmetic applications. This study employed a simple process to obtain growth factor composites from activated platelets of porcine origin, namely skin renewal growth factors (SRGF). The functions of SRGF were subsequently evaluated on cultured human fibroblasts, keratinocytes, and melanocytes. Our data revealed that SRGF significantly promoted the proliferation of fibroblasts, accompanied by increased expression of collagens (types I, III, IV, and VIII) and proteoglycans. Diminished proliferation and arrested differentiation of keratinocytes were evidenced by the attenuated expression of laminin V and keratin 10. In addition, SRGF also suppressed the growth of melanocytes and reduced the expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and paired box 3 (PAX3), which mediates melanogensis. Our results suggest that SRGF possesses beneficial properties and is a promising and cost-effective composition for the development of a safe cosmetic agent or topical products for skin regeneration. The development of SRGF may also provide an alternative strategy for tissue engineering.

  18. Effects of dietary wheat middlings, distillers dried grains with solubles, and choice white grease on growth performance, carcass characteristics, and carcass fat quality of finishing pigs.

    Science.gov (United States)

    Salyer, J A; DeRouchey, J M; Tokach, M D; Dritz, S S; Goodband, R D; Nelssen, J L; Petry, D B

    2012-08-01

    Two experiments were conducted to evaluate the effects of adding combinations of wheat middlings (midds), distillers dried grains with solubles (DDGS), and choice white grease (CWG) to growing-finishing pig diets on growth, carcass traits, and carcass fat quality. In Exp. 1, 288 pigs (average initial BW = 46.6 kg) were used in an 84-d experiment with pens of pigs randomly allotted to 1 of 4 treatments with 8 pigs per pen and 9 pens per treatment. Treatments included a corn-soybean meal-based control, the control with 30% DDGS, the DDGS diet with 10% midds, or the DDGS diet with 20% midds. Diets were fed in 4 phases and formulated to constant standardized ileal digestible (SID) Lys:ME ratios within each phase. Overall (d 0 to 84), pigs fed diets containing increasing midds had decreased (linear, P ≤ 0.02) ADG and G:F, but ADFI was not affected. Feeding 30% DDGS did not influence growth. For carcass traits, increasing midds decreased (linear, P pigs (initial BW = 42.3 kg) were used in an 87-d experiment with pens of pigs randomly allotted to 1 of 6 dietary treatments with 8 pigs per pen and 6 pens per treatment. Treatments were arranged in a 2 × 3 factorial with 2 amounts of midds (0 or 20%) and 3 amounts of CWG (0, 2.5, or 5.0%). All diets contained 15% DDGS. Diets were fed in 4 phases and formulated to constant SID Lys:ME ratios in each phase. No CWG × midds interactions were observed. Overall (d 0 to 87), feeding 20% midds decreased (P Pigs increasing CWG had improved ADG (quadratic, P = 0.03) and G:F (linear, P Dietary midds or CWG did not affect ADFI. For carcass traits, feeding 20% midds decreased (P Pigs fed CWG had decreased (linear, P pig growth performance, carcass yield, and increased jowl fat iodine value. Although increasing diet energy with CWG can help mitigate negative effects on live performance, CWG did not eliminate negative impacts of midds on carcass yield, HCW, and jowl fat iodine value.

  19. Grain Spectroscopy

    Science.gov (United States)

    Allamandola, L. J.

    1992-01-01

    Our fundamental knowledge of interstellar grain composition has grown substantially during the past two decades thanks to significant advances in two areas: astronomical infrared spectroscopy and laboratory astrophysics. The opening of the mid-infrared, the spectral range from 4000-400 cm(sup -1) (2.5-25 microns), to spectroscopic study has been critical to this progress because spectroscopy in this region reveals more about a materials molecular composition and structure than any other physical property. Infrared spectra which are diagnostic of interstellar grain composition fall into two categories: absorption spectra of the dense and diffuse interstellar media, and emission spectra from UV-Vis rich dusty regions. The former will be presented in some detail, with the latter only very briefly mentioned. This paper summarized what we have learned from these spectra and presents 'doorway' references into the literature. Detailed reviews of many aspects of interstellar dust are given.

  20. Grain size effect on the giant dielectric constant of CaCu{sub 3}Ti{sub 4}O{sub 12} nanoceramics prepared by mechanosynthesis and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Mohamad M., E-mail: mmohamad@kfu.edu.sa [Department of Physics, College of Science, King Faisal University, Al-Ahsaa 31982 (Saudi Arabia); Department of Physics, Faculty of Science, Assiut University in the New Valley, El-Kharga 72511 (Egypt); Yamada, Koji [Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Narashino, Chiba 275-8575 (Japan)

    2014-04-21

    In the present work, CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) nanoceramics with different grain sizes were prepared by spark plasma sintering (SPS) at different temperatures (SPS-800, SPS-900, SPS-975, and SPS-1050) of the mechanosynthesized nano-powder. Structural and microstructural properties were studied by XRD and field-emission scanning electron microscope measurements. The grain size of CCTO nanoceramics increases from 80 nm to ∼200 nm for the ceramics sintered at 800 °C and 975 °C, respectively. Further increase of SPS temperature to 1050 °C leads to micro-sized ceramics of 2–3 μm. The electrical and dielectric properties of the investigated ceramics were studied by impedance spectroscopy. Giant dielectric constant was observed in CCTO nanoceramics. The dielectric constant increases with increasing the grain size of the nanoceramics with values of 8.3 × 10{sup 3}, 2.4 × 10{sup 4}, and 3.2 × 10{sup 4} for SPS-800, SPS-900, and SPS-975, respectively. For the micro-sized SPS-1050 ceramics, the dielectric constant dropped to 2.14 × 10{sup 4}. The dielectric behavior is interpreted within the internal barrier layer capacitance picture due to the electrical inhomogeneity of the ceramics. Besides the resistive grain boundaries that are usually observed in CCTO ceramics, domain boundaries appear as a second source of internal layers in the current nanoceramics.

  1. Biofuel feedstock and blended coproducts compared with deoiled corn distillers grains in feedlot diets: Effects on cattle growth performance, apparent total tract nutrient digestibility, and carcass characteristics.

    Science.gov (United States)

    Opheim, T L; Campanili, P R B; Lemos, B J M; Ovinge, L A; Baggerman, J O; McCuistion, K C; Galyean, M L; Sarturi, J O; Trojan, S J

    2016-01-01

    Crossbred steers (British × Continental; = 192; initial BW 391 ± 28 kg) were used to evaluate the effects of feeding ethanol coproducts on feedlot cattle growth performance, apparent nutrient digestibility, and carcass characteristics. Steers were blocked by initial BW and assigned randomly to 1 of 6 dietary treatments within block. Treatments (replicated in 8 pens with 4 steers/pen) included 1) control, steam-flaked corn-based diet (CTL), 2) corn dried distillers grains with solubles (DGS; DRY-C), 3) deoiled corn dried DGS (DRY-CLF), 4) blended 50/50 corn/sorghum dried DGS (DRY-C/S), 5) sorghum dried DGS (DRY-S), and 6) sorghum wet DGS (WET-S). Inclusion of DGS was 25% (DM basis). The DGS diets were isonitrogenous, CTL was formulated for 13.5% CP, and all diets were balanced for ether extract. Final shrunk BW, ADG, and DMI did not differ among CTL and DGS treatments ( ≥ 0.19). Overall G:F did not differ from CTL for DRY-C, DRY-CLF, or WET-S ( ≥ 0.12); however, G:F was 9.6% less for DRY-S compared with CTL ( < 0.01) and tended ( = 0.09) to be less for DRY-C/S than CTL. For grain source, ADG and G:F were less for DRY-S vs. DRY-C ( < 0.05), but blending DRY-C/S tended ( = 0.07) to increase ADG and increased ( = 0.05) carcass-adjusted G:F vs. DRY-S. For WET-S, final BW and ADG were greater ( < 0.05), and G:F tended ( = 0.06) to be greater than for DRY-S. There was no difference in ADG, DMI, or G:F of steers fed DRY-C vs. DRY-CLF ( ≥ 0.35). Apparent DM and OM digestibility did not differ for CTL, DRY-C, DRY-CLF, and WET-S ( ≥ 0.30) but were lower for DRY-C/S and DRY-S ( < 0.05). Nutrient digestibility was lower for DRY-S vs. DRY-C ( < 0.01), but apparent digestibility of OM, DM, NDF, ADF, CP, ether extract, and starch were increased ( < 0.01) for DRY-C/S vs. DRY-S. Although starch digestibility did not differ between DRY-S and WET-S ( 0.18), digestibility of other measured nutrients was greater for WET-S vs. DRY-S ( < 0.01). Ether extract digestibility was

  2. 不同谷物培养基上白灵1号与白灵801号菌丝生长情况研究%The Study on the Mycelium Growth of the Pleurotus nerbrodensis No.1 and No.801 in the Grain Medium

    Institute of Scientific and Technical Information of China (English)

    柴美清; 李青; 韩鹏远; 赵毅

    2015-01-01

    为找出适合白灵菇菌丝生长的谷物颗粒培养基,给白灵菇菌丝体的培养、提取与白灵菇栽培料的制备提供一定依据.在微生物实验室内采用随机区组试验,以白灵1号与白灵801为供试菌株,通过对菌丝萌发时间、颜色、密度、均匀度、平均生长速率和生长指数进行比较,探讨7种不同谷物(脱壳与不脱壳)对白灵菇菌丝生长的影响.结果表明,无论脱壳与否,白灵1号与白灵801在供试的7种谷物培养基上均能生长,但生长情况各不相同,其中最适合供试白灵1号菌株菌丝生长的是脱壳高粱培养基,其次为不脱壳的小麦和高粱培养基,最适白灵801生长的是不脱壳大麦培养基,其次为不脱壳小麦、荞麦、高粱米培养基.通过对比,在脱壳谷物培养基上(除荞麦外)白灵1号菌丝生长指数较高,在不脱壳谷物培养基上(除大黄米外)白灵801菌丝生长指数较高.综合各项因素,不论脱壳与否,高粱、小麦、大麦培养基相对适合白灵菇菌丝的生长.%In order to find out the grain medium that appropriate mycelium growth of Pleurotus for providing evidence of Pleurotus mycelium cultivate and extract, preparation planting material. The study carrying out in experiment on microbiology using randomized block design. The tested materials of this experiment ware Pleurotus nebrodensis No.1 and Pleurotus nebrodensis No.801. The affection on the growth of Pleurotus nebrodensis from 7 kinds of grain medium (shelling and no shelling) were explored through comparing mycelium germination time, color, density, uniformity, the average growth rate and growth index. The results showed that whether shelling or not, both Pleurotus nebrodensis No.1 and No.801 can grow in the 7 kinds of grain medium, but the growth situation was different. Shelling sorghum culture medium was the most suitable for Pleurotus nebrodensis mycelium growth. The followed medium was no shelling wheat, buckwheat and

  3. Effects of PVP on the preparation and growth mechanism of monodispersed Ni nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Monodispersed Ni nanoparticles were successfully prepared by chemical reduction with hydrazine hydrate in ethylene glycol.The effect of the amount of polyvinylpyrrolidone (PVP-K30) on the preparation of Ni nanoparticles was investigated.X-ray diffraction (XRD),transmission electron microscopy (TEM),and high resolution transmission electron microscopy (HRTEM) were employed to characterize the nickel particles are spherical in shape and are not agglomerated.A possible extensive mechanism of nickel nanoparticle formation has been suggested.

  4. Three-dimensional Numerical Simulation and Experimental Analysis of Austenite Grain Growth Behavior in Hot Forging Processes of 300M Steel Large Components

    Institute of Scientific and Technical Information of China (English)

    Jiao LUO; Ying-gang LIU; Miao-quan LI

    2016-01-01

    The microstructure models were integrated into finite element (FE)code,and a three-dimensional (3D) FE analysis on the entire hot forging processes of 300M steel large components was performed to predict the distri-butions of effective strain,temperature field and austenite grain size.The simulated results show that the finest grains distribute in the maximum effective strain region because large strain induces the occurrence of dynamic re-crystallization.However,coarse macro-grains appear in the minimum effective strain region.Then,300M steel forg-ing test was performed to validate the results of FE simulation,and microstructure observations and quantitative analysis were implemented.The average relative difference between the calculated and experimental austenite grain size is 7.5 6%,implying that the present microstructure models are reasonable and can be used to analyze the hot forging processes of 300M steel.

  5. Lag phase is a distinct growth phase that prepares bacteria for exponential growth and involves transient metal accumulation.

    Science.gov (United States)

    Rolfe, Matthew D; Rice, Christopher J; Lucchini, Sacha; Pin, Carmen; Thompson, Arthur; Cameron, Andrew D S; Alston, Mark; Stringer, Michael F; Betts, Roy P; Baranyi, József; Peck, Michael W; Hinton, Jay C D

    2012-02-01

    Lag phase represents the earliest and most poorly understood stage of the bacterial growth cycle. We developed a reproducible experimental system and conducted functional genomic and physiological analyses of a 2-h lag phase in Salmonella enterica serovar Typhimurium. Adaptation began within 4 min of inoculation into fresh LB medium with the transient expression of genes involved in phosphate uptake. The main lag-phase transcriptional program initiated at 20 min with the upregulation of 945 genes encoding processes such as transcription, translation, iron-sulfur protein assembly, nucleotide metabolism, LPS biosynthesis, and aerobic respiration. ChIP-chip revealed that RNA polymerase was not "poised" upstream of the bacterial genes that are rapidly induced at the beginning of lag phase, suggesting a mechanism that involves de novo partitioning of RNA polymerase to transcribe 522 bacterial genes within 4 min of leaving stationary phase. We used inductively coupled plasma mass spectrometry (ICP-MS) to discover that iron, calcium, and manganese are accumulated by S. Typhimurium during lag phase, while levels of cobalt, nickel, and sodium showed distinct growth-phase-specific patterns. The high concentration of iron during lag phase was associated with transient sensitivity to oxidative stress. The study of lag phase promises to identify the physiological and regulatory processes responsible for adaptation to new environments.

  6. Sistemas de manejo de plantas daninhas no desenvolvimento e na produtividade da soja Burndown systems on growth and grain yield in soybeans in Paraná State, Brazil

    Directory of Open Access Journals (Sweden)

    Jamil Constantin

    2009-01-01

    glyphosate occurred within 48 hours prior to sowing. The trials were developed in 2003/2004 growing season, in six localities in Paraná State: Sertãozinho, Campo Mourão, Iretama, Pitanga, Boa Esperança, and Mamborê, in areas with high density of weeds preceding no-till soybean sowing. Evaluations related to weed control and soybean development and grain yield were performed. MA burndown systems provided improved control of weeds after crop emergence. Soybean plants from AP areas were shorter, in comparison to ME, evidencing a delay in the shoot growth. Reduction of grain yield was verified for all localities when AP burndown system was adopted, with reductions between 15% and 50%.

  7. Antioxidant activity and growth inhibition of human colon cancer cells by crude and purified fucoidan preparations extracted from Sargassum cristaefolium

    Directory of Open Access Journals (Sweden)

    Cheng-Yuan Wang

    2015-12-01

    Full Text Available Fucose-containing sulfated polysaccharides, also termed “fucoidans”, which are known to possess antioxidant, anticoagulant, anticancer, antiviral, and immunomodulating properties, are normally isolated from brown algae via various extraction techniques. In the present study, two methods (SC1 and SC2 for isolation of fucoidan from Sargassum cristaefolium were compared, with regard to the extraction yields, antioxidant activity, and inhibition of growth of human colon cancer cells exhibited by the respective extracts. SC1 and SC2 differ in the number of extraction steps and concentration of ethanol used, as well as the obtained sulfated polysaccharide extracts, namely, crude fucoidan preparation (CFP and purified fucoidan preparation (PFP, respectively. Thin layer chromatography, Fourier transform infrared analysis, and measurements of fucose and sulfate contents revealed that the extracts were fucoidan. There was a higher extraction yield for CFP, which contained less fucose and sulfate but more uronic acid, and had weaker antioxidant activity and inhibition of growth in human colon cancer cells. In contrast, there was a lower extraction yield for PFP, which contained more fucose and sulfate but less uronic acid, and had stronger antioxidant activity and inhibition of growth in human colon cancer cells. Thus, since the difference in bioactive activities between CFP and PFP was not remarkable, the high extraction yield of SC1 might be favored as a method in industrial usage for extracting fucoidan.

  8. Impact of Industrialization on Grain Consumption and Countermeasures

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    This paper analyzes the impact of industrialization on grain consumption from growth of residents’ income and change of diet structure,expansion of size of population,and development of new biomass energy industry.The economic growth in the course of industrialization promotes growth of residents’ income,changes residents’ diet structure;industrialization leads to rural urbanization and rise of urban residents;industrial development brings about grain demand of biomass energy.All of these greatly increase demand of grain consumption.On the basis of these situations,it presents following countermeasures to guarantee grain consumption demand in the course of industrialization:heighten awareness to fully realize the significance of rapid development of industrialization to grain security;control population growth and improve grain conversion ratio;strengthen grain-saving construction and advocate moderate consumption;develop non-grain biomass energy in many channels to guarantee grain security.

  9. EFFECT OF TREATMENT WITH MOLD INHIBITORS ON PLANT GROWTH OF CORN AND SOME NUTRITIONAL COMPONENTS OF STORED GRAINS, INFECTED WITH A. FLAVUS AND F. VERTICILLOIDES

    Directory of Open Access Journals (Sweden)

    Mervat S. Youssef

    2012-12-01

    Full Text Available Planting sterilized corn grains in soil, treated with the mold inhibitors Fix-a-tox (FAT or Antitox Plus (AP resulted, in cases, in dwarfed and malformed corn plants and in the development of deformed, bone-shaped and grain-free corn cobs. Moreover, treating corn grains with the mold inhibitors before storage for one month caused significant changes in some nutritional components of corn grains, i.e. proteins, aminoacids, crude fibers, moisture, fats, ash and carbohydrates. Insignificant differences in protein percetage were detected between control inoculated with Aspergillus flavus and those treated with butyl hydroxyanisole (BHA antioxidant or FAT treatments, whereas ground clove significantly reduced protein content. In corn grains inoculated with Fusariumverticillioides, previous treatment with FAT resulted in significant reduction in the content of proline, aspartic acid, cysteine, valine, isoleucine and leucine, whereas treatment with BHA significantly reduced the content of threonine, serine, glutamic, glycine, alanine, phenylalanine and tyrosine. In Aspergillus flavus treatments, FAT significantly increased the content of methionine and threonine, whereas, aspartic acid showed 26 percentage decreases, compared to the control. Pronounced reductions in threonine, isoleucine and leucine were also detected in corn grains treated with BHA. Significant increases in fiber content were detected in inoculated corn grains treated with BHA, attaining 1.34 to 2.05-fold over that of control, respectively. Treatment with FAT and BHA led to pronounced reductions in moisture content in corn inoculated with both F. verticilloides and A. flavus trials. However, treatment with ground clove significantly increased the moisture content in A. flavus treatment. FAT treatment led to significant increase in ash and fat contents in both A. flavus and F. verticilloides treatments, whereas the other tested treatments of F. verticilloides significantly

  10. 粉末冶金法制备超细晶AZ31镁合金及超塑性变形研究%Powder Metallurgy Prepared Ultra-fine Grain AZ31 Alloy and Its Superplastic Deformation

    Institute of Scientific and Technical Information of China (English)

    林莺莺; 胡杰仁

    2013-01-01

    采用粉末冶金法制备超细晶AZ31镁合金材料,并对其微观组织形貌及相成分进行研究;利用单向拉伸试验研究了该材料在不同条件下超塑性变形.结果表明,采用球磨、冷压制坯和热挤压法可获得晶粒尺寸在1微米以下的超细晶组织,该材料在250℃,1×10-3s-1的应变速率条件下获得了最大伸长率,基本达到超塑性状态.%Ultra-fine grain AZ31 alloy bars were fabricated by power metallurgy process,and the microstructure and phase composition were also researched.The superplastic deformation was studied by simple tension test.According to the results,AZ31 alloy with the grain size under 1 μm was prepared by the process of high energy ball milling,cold compacting and hot extrusion.The superplastic deformation was achieved under the temperature of 250 ℃ and strain rate of 1 × 10-3 s-1.

  11. Deformation Behaviour of Coarse Grain Alumina under Shock Loading

    Science.gov (United States)

    Gupta, Satish

    2013-06-01

    To develop better understanding of the shock wave induced deformation behavior of coarse grain alumina ceramics, and for measurement of its Hugoniot Elastic Limit (HEL), in-situ and recovery gas gun experiments have been carried out on coarse grain alumina (grain size ~ 10 μm), prepared in the form of discs (>99.9% TMD) by pressure-less sintering of alpha alumina powder at 1583 K. The HEL value of 1.9 GPa has been determined from the kink in the pressure history recorded using piezoresistance gauge and also from the free surface velocity history of the sample shocked to 9 GPa. The nano-indentation measurements on the alumina samples shocked to 6.5 GPa showed hardness value 15% lower than 21.3 GPa for unshocked alumina, and strong Indentation Size Effect (ISE); the hardness value was still lower and the ISE was stronger for the sample shocked to 12 GPa. The XRD measurements showed reduced particle size and increased microstrains in the shocked alumina fragments. SEM, FESEM and TEM measurements on shock treated samples showed presence of grain localized micro- and nano-scale deformations, micro-cleavages, grain-boundary microcracks, extensive shear induced deformations, and localized micro-fractures, etc. These observations led to the development of a qualitative model for the damage initiation and its subsequent growth mechanisms in shocked alumina. The work performed in collaboration with K.D. Joshi of BARC and A.K. Mukhopadhyay of CGCRI.

  12. 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.

  13. Effects of adding supplemental tallow to diets containing 30% distillers dried grains with solubles on growth performance, carcass characteristics, and pork fat quality in growing-finishing pigs.

    Science.gov (United States)

    Davis, J M; Urriola, P E; Shurson, G C; Baidoo, S K; Johnston, L J

    2015-01-01

    Crossbred pigs (n = 315) were blocked by initial BW (6.8 ± 1.1 kg) and randomly assigned to 1 of 4 dietary treatments to evaluate the effects of dietary inclusion of tallow and corn distillers dried grains with solubles (DDGS) on pig growth, carcass traits, and pork fat quality. Diets consisted of a corn-soybean meal control diet (CON) and another 3 corn-soybean meal diets containing 5% tallow (T), 30% DDGS (D), or 5% tallow plus 30% DDGS (TD) in a 2 × 2 factorial arrangement of treatments. Diets were formulated to contain similar levels of available P and standardized ileal digestible Lys:ME among treatments. Pigs were housed in 40 pens, with 7 to 8 pigs per pen, to provide 10 replicates per treatment. Overall ADG did not differ among treatments. Compared with CON (2.76 kg/d) and T (2.59 kg/d), feeding 30% DDGS reduced the ADFI (interaction, P > 0.05) of pigs when fed with 5% tallow (2.45 kg/d for TD) but not when fed alone (2.76 kg/d for D). There was no effect of DDGS on overall G:F, but pigs fed diets with tallow had greater (P tallow (0.37). Feeding tallow increased (P tallow (D = 71.8° and TD = 57.7° vs. CON = 134.0° and T = 113.4°) and tallow also tended to reduce belly firmness (P tallow reduced the concentration of SFA in belly fat, while the concentration of MUFA were increased (P tallow but not DDGS. Conversely, feeding DDGS increased (P tallow. An interaction (P = 0.03) between DDGS and tallow for iodine value (IV) of belly fat was observed, in which addition of tallow or DDGS increased the IV of belly fat (64.22 for T and 71.22 for D vs. 59.01 for CON) but addition of both reduced IV (67.88 for TD). The IV of belly fat and backfat were correlated (P tallow to 30% DDGS diets improved G:F and carcass yield while reducing the IV of belly fat. However, pork fat firmness as measured by belly flop angle was not improved.

  14. Effect of feeding peroxidized dried distillers grains with solubles to sows and progeny on growth performance and metabolic oxidative status of nursery pigs.

    Science.gov (United States)

    Hanson, A R; Wang, L; Johnston, L J; Baidoo, S K; Torrison, J L; Chen, C; Shurson, G C

    2015-01-01

    This experiment evaluated the effects of including peroxidized corn dried distillers grains with solubles (DDGS) in diets for sows and nursery pigs on growth performance, vitamin E (VE), and Se status, and the incidence of mulberry heart disease (MHD) of nursery pigs. Sows (n = 12) were fed corn-soybean meal diets (C-SBM) or C-SBM diets with DDGS (40% and 20% in gestation and lactation, respectively) for 3 parities. In the third parity, 108 weaned pigs (BW = 6.6 ± 0.36 kg) were blocked by BW within litter, assigned to pens (2 pigs/pen; 5 and 4 pens per litter for groups 1 and 2, respectively), and pens were assigned 1 of 3 nursery diets: 1) corn-soybean meal (CON), 2) 30% peroxidized DDGS (Ox-D), and 3) 30% Ox-D with 5 × NRC (1998) level of VE (Ox-D+5VE) for 7 wk, in a 2 × 3 factorial arrangement of sow and nursery diets (n = 9 pens/treatment). The peroxidized DDGS source in nursery diets contained concentrations of thiobarbituric acid reactive substances (TBARS) and peroxide values that were 25 and 27 times greater than a reference corn sample. Sow colostrum, milk, and serum, as well as pig serum and liver samples, were analyzed for α-tocopherol and Se concentrations. Pig serum was analyzed for glutathione peroxidase activity (GPx), TBARS, and sulfur-containing AA (SAA). Pig hearts were evaluated for gross and histopathological lesions indicative of MHD, but none were detected. Pigs from sows fed DDGS tended to have reduced (P = 0.07) VE in serum during lactation and reduced VE at weaning (P pigs from sows fed C-SBM. Inclusion of DDGS in sow diets reduced the VE status of pigs during lactation, but not in the nursery when MHD can be a concern. Pigs fed Ox-D+5VE (P = 0.08) tended to have, and those fed Ox-D (P = 0.04) had greater ADFI than pigs fed CON, but ADG was not affected (P > 0.1) by nursery diet. Feeding Ox-D or Ox-D+5VE increased (P pigs fed Ox-D or Ox-D+5VE compared with those fed C-SBM, which was likely due to greater (P pigs fed Ox-D. The

  15. Effects of late gestation distillers grains supplementation on fall-calving beef cow performance and steer calf growth and carcass characteristics.

    Science.gov (United States)

    Wilson, T B; Schroeder, A R; Ireland, F A; Faulkner, D B; Shike, D W

    2015-10-01

    Fall-calving, mature Angus and Simmental × Angus cows ( = 251 total) and their progeny were used to evaluate the effects of late gestation dried distillers grains plus solubles (DDGS) supplementation on cow performance and progeny growth and carcass characteristics. Cows were blocked by breed and allotted to 12 tall fescue pastures (6.8 ha average). Pastures were randomly assigned to 1 of 2 treatments: cows were offered 2.1 kg DM DDGS·cow·d (SUP; CP = 23%, fat = 7%; = 6 pastures) or were not offered a supplement (CON; = 6 pastures) 69 ± 9 d before expected calving date. Cows remained on treatments until calving. Once weekly, cows that had calved were removed from treatment pastures and were moved to new tall fescue pastures (21.6 ha average) where cows from both treatments were comingled without further supplementation. Cows ( = 74) were removed from study for calving more than 30 d after expected calving date, calf loss and injury, or euthanasia. Cow BW and BCS were recorded at the beginning of the supplementation period, after calving, and at breeding. Calf BW was taken at birth and early weaning (82 ± 14 d of age). After weaning, 71 steer progeny (representative of dam breed and treatment pastures) were transitioned to a common feedlot diet with individual feed intake monitored using the GrowSafe feeding system. Steers were slaughtered at 47 ± 4 d after a minimum 12th rib fat thickness (back fat) estimation of 0.6 cm, with cattle being shipped in 3 groups. Forage availability was not different between treatments ( = 0.69). Cows offered SUP gained more BW and BCS ( ≤ 0.02) during the supplementation period. There were no differences ( ≥ 0.12) in calving date, calf birth or weaning BW, or preweaning ADG. Cow BW at breeding was not different ( = 0.19); however, BCS at breeding was greater ( feed were not different ( ≥ 0.35); no difference ( = 0.77) in feedlot ADG was detected. Feedlot DMI and G:F were not different ( ≥ 0.52) across treatments. No

  16. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    H Ramanarayan; T A Abinandanan

    2003-01-01

    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 ($\\lambda_{SD}$). In the spirit of phase field models, each grain () in our model has an order parameter ($\\eta_i$) associated with it; $\\eta_i$ has a value of unity inside the th grain, decreases smoothly through the grain boundary region to zero outside the grain. For a symmetric alloy of composition, = 0.5, our results show that microstructural evolution depends largely on the difference in the grain boundary energies, $\\gamma_{gb}$, of A-rich () and B-rich () phases. If $\\gamma^{\\alpha}_{gb}$ is lower, we find that the decomposition process is initiated with an layer being formed at the grain boundary. If the grain size is sufficiently small (about the same as $\\lambda_{SD}$), the interior of the grain is filled with the phase. If the grain size is large (say, about 10 $\\lambda_{SD}$ or greater), the early stage microstructure exhibits an A-rich grain boundary layer followed by a B-rich layer; the grain interior exhibits a spinodally decomposed microstructure, evolving slowly. Further, grain growth is suppressed completely during the decomposition process.

  17. Ordered mesoporous silica prepared by quiescent interfacial growth method - effects of reaction chemistry

    Science.gov (United States)

    Alsyouri, Hatem M.; Abu-Daabes, Malyuba A.; Alassali, Ayah; Lin, Jerry YS

    2013-11-01

    Acidic interfacial growth can provide a number of industrially important mesoporous silica morphologies including fibers, spheres, and other rich shapes. Studying the reaction chemistry under quiescent (no mixing) conditions is important for understanding and for the production of the desired shapes. The focus of this work is to understand the effect of a number of previously untested conditions: acid type (HCl, HNO3, and H2SO4), acid content, silica precursor type (TBOS and TEOS), and surfactant type (CTAB, Tween 20, and Tween 80) on the shape and structure of products formed under quiescent two-phase interfacial configuration. Results show that the quiescent growth is typically slow due to the absence of mixing. The whole process of product formation and pore structuring becomes limited by the slow interfacial diffusion of silica source. TBOS-CTAB-HCl was the typical combination to produce fibers with high order in the interfacial region. The use of other acids (HNO3 and H2SO4), a less hydrophobic silica source (TEOS), and/or a neutral surfactant (Tweens) facilitate diffusion and homogenous supply of silica source into the bulk phase and give spheres and gyroids with low mesoporous order. The results suggest two distinct regions for silica growth (interfacial region and bulk region) in which the rate of solvent evaporation and local concentration affect the speed and dimension of growth. A combined mechanism for the interfacial bulk growth of mesoporous silica under quiescent conditions is proposed.

  18. GRAIN GROWTH MODEL OF INCONEL 718 ALLOY FORGED SLAB IN REHEATING PROCESS PRIOR TO ROUGH ROLLING%Inconel 718合金方坯粗轧加热过程晶粒长大模型

    Institute of Scientific and Technical Information of China (English)

    陈礼清; 隋凤利; 刘相华

    2009-01-01

    The Inconel 718 superalloy is extensively used to manufacture critical parts in aero-nautical, astronautical, oil and chemical industries due to its excellent mechanical, physical and anti-corrosion behavior. Usually, these parts are shaped by hot forging or rolling in open-train mills. Recently, the tandem hot rolling has been applied to form superalloy bar products. In some cases, it can replace the traditional rolling, since it has higher productivity and product quality. In order to obtain the most favorable microstructure and the best mechanical properties of Inconel 718 alloy in tandem hot rolling, it is necessary to control its microstructural evolution in every step of the whole rolling process. With the aid of computer modeling, it is possible to make such a controlling process possible. As the first step in tandem hot rolling, reheating process of a forged slab prior to rough rolling plays a predominant role in predicting the grain size change or even the microstructural evo-lution. Thus, in this study, an Inconel 718 alloy forged slab was used as the experimental material and the effects of reheating temperature and holding time on its grain growth were investigated. A universal model was developed and verified for the grain growth of Inconel 718 alloy forged slab in reheating process prior to rough rolling. With the increase of holding time, the grain size shows no remarkable change up to 1173 K. The grain growth presents a linear trend in the range from 1173 to 1323 K. A parabolic trend of grain growth can be observed when reheating temperature is higher than 1323 K. The established grain growth model of Inconel 718 alloy would be suitable to calculate the