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Sample records for ball-milling multiscale characterizations

  1. Characterization of ball-milled B/CaCrO/sub 4/

    SciTech Connect

    Love, C.M.; Glaub, J.E.

    1985-10-18

    Ball-milling of B/CaCrO/sub 4/ is being incorporated as a step in the production procedure of this pyrotechnic material. In order to understand the effects of this operation, two series of ball-milled B/CaCrO/sub 4/ samples were prepared and characterized as a function of ball-milling time. Analytical examinations included optical and scanning electron microscopy, thermal analysis, calorific output determinations, infrared analyses, x-ray diffraction, x-ray photoelectron spectroscopy, three particle morphology methods, emission spectroscopy, and electrostatic sensitivity measurements. The results of these examinations indicate that a short ball-milling time should be used because this will eliminate material inhomogeneity and increase ignition sensitivity. Furthermore, the results indicate that long-term ball-milling should not be employed in order to avoid reduced calorific output, increased impurities, and dangerous electrostatic discharge sensitivity. A Coulter Counter particle size method appears to give a good index for comparing the effectiveness of different B/CaCrO/sub 4/ ball-milling times and procedures. 2 refs., 10 figs., 3 tabs.

  2. Selective ensemble modeling load parameters of ball mill based on multi-scale frequency spectral features and sphere criterion

    NASA Astrophysics Data System (ADS)

    Tang, Jian; Yu, Wen; Chai, Tianyou; Liu, Zhuo; Zhou, Xiaojie

    2016-01-01

    It is difficult to model multi-frequency signal, such as mechanical vibration and acoustic signals of wet ball mill in the mineral grinding process. In this paper, these signals are decomposed into multi-scale intrinsic mode functions (IMFs) by the empirical mode decomposition (EMD) technique. A new adaptive multi-scale spectral features selection approach based on sphere criterion (SC) is applied to these IMFs frequency spectra. The candidate sub-models are constructed by the partial least squares (PLS) with the selected features. Finally, the branch and bound based selective ensemble (BBSEN) algorithm is applied to select and combine these ensemble sub-models. This method can be easily extended to regression and classification problems with multi-time scale signal. We successfully apply this approach to a laboratory-scale ball mill. The shell vibration and acoustic signals are used to model mill load parameters. The experimental results demonstrate that this novel approach is more effective than the other modeling methods based on multi-scale frequency spectral features.

  3. Characterization of ball-milled carbon nanotube dispersed aluminum mixed powders

    NASA Astrophysics Data System (ADS)

    Maleque, M. A.; Abdullah, U.; Yaacob, I.; Ali, Y.

    2016-04-01

    Currently, carbon nanotube (CNT) is attracting much interest as fibrous materials for reinforcing aluminum matrix composites due to unique properties, such as high strength, elastic modulus, flexibility and high aspect ratios. However, the quality of the dispersion is the major concerning factor which determines the homogeneity of the enhanced mechanical and tribological properties of the composite. This work study and characterized carbon nanotube dispersion in ballmilled CNT-aluminum mixed powders with four different formulations such as 1, 1.5, 2 and 2.5 wt% CNT under high energy planetary ball milling operations. The ball milling was performed for two hours at constant milling speed of 250 rpm under controlled atmosphere. The characterization is performed using FESEM and EDX analyzer for mapping, elemental and line analysis. The experimental results showed homogeneous dispersion of CNTs in aluminum matrix. The composite mixture showed similar pattern from mapping, elemental and line analysis. Identification of only two peaks proved that controlled atmosphere during milling prevented the formation of inter metallic compounds such as aluminum carbide in the composite mixture. Therefore, this CNT-A1 composite powder mixture can be used for new nano-composite development without any agglomeration problem.

  4. Preparation, characterization and optoelectronic properties of nanodiamonds doped zinc oxide nanomaterials by a ball milling technique

    NASA Astrophysics Data System (ADS)

    Ullah, Hameed; Sohail, Muhammad; Malik, Uzma; Ali, Naveed; Bangash, Masroor Ahmad; Nawaz, Mohsan

    2016-07-01

    Zinc oxide (ZnO) is one of the very important metal oxides (MOs) for applications in optoelectronic devices which work in the blue and UV regions. However, to meet the challenges of obtaining ZnO nanomaterials suitable for practical applications, various modifications in physico-chemical properties are highly desirable. One of the ways adopted for altering the properties is to synthesize composite(s) of ZnO with various reinforcements. Here we report on the tuning of optoelectronic properties of ZnO upon doping by nanodiamonds (NDs) using the ball milling technique. A varying weight percent (wt.%) of NDs were ball milled for 2 h with ZnO nanoparticles prepared by a simple precipitation method. The effects of different parameters, the calcination temperature of ZnO, wt.% of NDs and mechanical milling upon the optoelectronic properties of the resulting ZnO–NDs nanocomposites have been investigated. The ZnO–NDs nanocomposites were characterized by IR spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The UV-vis spectroscopy revealed the alteration in the bandgap energy (Eg ) of ZnO as a function of the calcination temperature of ZnO, changing the concentration of NDs, and mechanical milling of the resulting nanocomposites. The photoluminescence (PL) spectroscopy showed a decrease in the deep level emission (DLE) peaks and an increase in near-band-edge transition peaks as a result of the increasing concentration of NDs. The decrease in DLE and increase in band to band transition peaks were due to the strong interaction between the NDs and the Zn+; consequently, the Zn+ concentration decreased on the interstitial sites.

  5. Characterization of cationic starch flocculants synthesized by dry process with ball milling activating method.

    PubMed

    Su, Yuting; Du, Hongying; Huo, Yinqiang; Xu, Yongliang; Wang, Jie; Wang, Liying; Zhao, Siming; Xiong, Shanbai

    2016-06-01

    The cationic starch flocculants were synthesized by the reaction of maize starch which was activated by a ball-milling treatment with 2,3-epoxypropyl trimethyl ammonium chlorides (ETMAC) using the dry method. The cationic starches were characterized by several approaches including scanning electron microscope (SEM), degree of substitution (DS), infrared spectrum (IR), X-ray diffraction (XRD), flocculating activity, electron spin resonance (ESR), and solid-state nuclear magnetic resonance (NMR). The effect of mechanical activation on starch etherifying modification was investigated. The mechanical activation cracked starch granules and destructed their crystal structures. This resulted in enhancements to the reaction activity and reaction efficiency, which was approved by ESR and solid state NMR. The starch flocculants, synthesized by the reaction of mechanically activated starches at 90°C for 2.5h with ETMAC at molar ratio of 0.40:1.00, showed good flocculation activity. The substitution degree (0.300) and reaction efficiency (75.06%) of starch flocculants synthesized with mechanically activated starches were significantly greater than those of starch flocculants with native starches (P<0.05). PMID:26905465

  6. Microstructural characterization of amorphous and nanocrystalline boron nitride prepared by high-energy ball milling

    SciTech Connect

    Ghosh, J. Mazumdar, S.; Das, M.; Ghatak, S.; Basu, A.K.

    2008-04-01

    Microstructural parameters like crystallite size, lattice strain, stacking faults and dislocation density were evaluated from the X-ray diffraction data of boron nitride (BN) powder milled in a high-energy vibrational ball mill for different length of time (2-120 h), using different model based approaches like Scherrer analysis, integral breadth method, Williamson-Hall technique and modified Rietveld technique. From diffraction line-broadening analysis of the successive patterns of BN with varying milling time, it was observed that overall line broadening was an operative cause for crystallite size reduction at lower milling time ({approx}5 h), whereas lattice strains were the prominent cause of line broadening at higher milling times (>19 h). For intermediate milling time (7-19 h), both crystallite size and lattice strain influence the profile broadening although their relative contribution vary with milling time. Microstructural information showed that after long time milling (>19 h) BN becomes mixture of nanocrystalline and amorphous BN. The accumulations of defects cause this crystalline to amorphous transition. It has been found that twin fault ({beta}') and deformation fault ({alpha}) significantly contributed to BN powder as synthesized by a high-energy ball-milling technique. Present study consider only three ball-milled (0, 2 and 3 h) BN powder for faults calculation because fault effected reflections (1 0 1, 1 0 2, 1 0 3) disappear with milling time (>3 h). The morphology and particle size of the BN powders before and after ball milling were also observed in a field emission scanning electron microscope (FESEM)

  7. Preparation and Characterization of Nano structured Materials from Fly Ash: A Waste from Thermal Power Stations, by High Energy Ball Milling

    PubMed Central

    2007-01-01

    The Class F fly ash has been subjected to high energy ball milling and has been converted into nanostructured material. The nano structured fly ash has been characterized for its particle size by using particle size analyzer, specific surface area with the help of BET surface area apparatus, structure by X-ray diffraction studies and FTIR, SEM and TEM have been used to study particle aggregation and shape of the particles. On ball milling, the particle size got reduced from 60 μm to 148 nm by 405 times and the surface area increased from 0.249 m2/gm to 25.53 m2/gm i.e. by more than 100%. Measurement of surface free energy as well as work of adhesion found that it increased with increased duration of ball milling. The crystallite was reduced from 36.22 nm to 23.01 nm for quartz and from 33.72 nm to 16.38 nm for mullite during ball milling to 60 h. % crystallinity reduced from 35% to 16% during 60 h of ball milling because of destruction of quartz and hematite crystals and the nano structured fly ash is found to be more amorphous. Surface of the nano structured fly ash has become more active as is evident from the FTIR studies. Morphological studies revealed that the surface of the nano structured fly ash is more uneven and rough and shape is irregular, as compared to fresh fly ash which are mostly spherical in shape.

  8. Highly Al-doped TiO{sub 2} nanoparticles produced by Ball Mill Method: structural and electronic characterization

    SciTech Connect

    Santos, Desireé M. de los Navas, Javier Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

    2015-10-15

    Highlights: • Highly Al-doped TiO{sub 2} nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO{sub 2} nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti{sup 4+} ions by Al{sup 3+} in the TiO{sub 2} lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature.

  9. Preparation and characterization of planetary ball milled Si-based clathrates and their spark plasma sintered materials

    NASA Astrophysics Data System (ADS)

    Shirataki, R.; Hokazono, M.; Nakabayashi, T.; Anno, H.

    2011-05-01

    Ba8Ga16Si30 clathrate particles ranging in size from several tens nanometers to submicron have been prepared by a planetary ball milling technique, and their sintered materials with microstructures have been prepared by a spark plasma sintering (SPS) technique. Relatively low temperature, short time and high pressure conditions of SPS are needed for the densification without the decomposition and/or the oxidation of clathrate phase. In comparison with Ba8Ga16Si30 prepared by SPS of micro powders, Ba8Ga16Si30 prepared by SPS of pulverized powders shows relatively large Seebeck coefficient about -100 μV/K at middle temperature range, low thermal diffusivity as low as 0.6 mm2/s (RT) and extremely low electrical conductivity of the orders of 0.1 - 1 S/cm (RT), due probably to the increased scattering at the interfaces and pores in the microstructures.

  10. Preparation and Characterization of MgB2 Bulk Samples Using High-Energy Ball Milling and Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Rodrigues, D.; Senkowicz, B. J.; Hanson, J. M.; Larbalestier, D. C.; Hellstrom, E. E.

    2008-03-01

    MgB2 bulk samples were prepared using high-energy ball milling in nitrogen atmosphere followed by cold isostatic pressing and hot isostatic pressing to increase densification and grain connectivity. Higher values of critical current densities Jc at high magnetic fields could be obtained after milling than those obtained with unmilled bulk samples. Jc values around 20,000 A/cm2 at 7 T, 4.2 K were found for the MgB2 sample milled for 300 minutes compared to 1000 A/cm2 for the unmilled material. The milling increased electron scattering and resistivity, increasing the irreversibility field μ0Hirr of the samples. The milled samples showed higher values of μ0Hirr than the unmilled sample. However, the milled samples showed lower pinning strength than the unmilled sample as a result of their larger average grain size after HIP, in spite of their higher μ0Hirr.

  11. Preparation of bismuth telluride based thermoelectric nanomaterials via low-energy ball milling and their property characterizations

    NASA Astrophysics Data System (ADS)

    Robinson, Christopher A.

    Thermoelectric materials are able to convert energy between heat and electricity with no moving parts, making them very appealing for power generation purposes. This is particularly appealing since many forms of energy generation lose energy to waste heat. The Livermore National Laboratory estimates that up to 55% of the energy created in traditional power plants is lost through heat generation [1]. As greenhouse gas emissions become a more important issue, large sources of waste like this will need to be harnessed. Adoption of these materials has been limited due to the cost and efficiency of current technology. Bismuth telluride based alloys have a dimensionless figure of merit, a measure of efficiency, near one at room temperature, which makes it the best current material. In order to compete with other forms of energy generation, this needs to be increased to three or higher [2]. Recently, improvements in performance have come in the form of random nanostructured materials [3]. Bulk bismuth telluride is subjected to particle size reduction via high-energy ball milling in order to scatter phonons between grains. This reduces the lattice thermal conductivity which in turn increases the performance of the material. In this work, we investigate the use of low-energy ball milling as a method of creating nanoparticles of n-type and p-type Bi2Te3 alloys for thermoelectric applications. Optimization of parameters such as milling containers, milling media, contamination and milling time has resulted in creating 15nm particles of bismuth telluride alloys. After creating solid pellets of the resulting powders via hot pressing, the material's thermal and electrical conductivities as well as Seebeck coefficients were measured. The ZT of n-type Bi2Te2.7Se3 created using this method is 0.32, while the p-type Bi0.5Sb1.5Te3 exhibits a higher ZT of 1.24, both at room temperature.

  12. Structural and magnetic characterization of the ball-milled α-Fe 2O 3-Mn 2O 3 and α-Fe-Mn 2O 3 systems

    NASA Astrophysics Data System (ADS)

    de Medeiros, S. N.; Luciano, A.; Cótica, L. F.; Santos, I. A.; Paesano, A.; da Cunha, J. B. M.

    2004-10-01

    In this work, the (Fe2O3)x(Mn2O3)1-x and Fey(Mn2O3)1-y systems were mechanically processed in a high-energy ball-mill. The as-milled powders were structurally and magnetically characterized by X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. Under similar milling settings and conditions, dissimilar behaviors were observed in the studied systems. In the oxide-oxide system, only the bixbyite (Mn,Fe)2O3 phase was obtained in all the analysed samples, whereas in the metal-oxide system, a sharp compositional dependence for the final milling products was observed. For y⩽0.40, the FeMn2O4 spinel phase was detected and, for y>0.40, a wustite-like phase of the (Fe, Mn)1-yO type was formed. It was observed that magnetization in both systems increased with the nominal concentration, x or y, of the magnetic precursors, up to half of the concentration maximum and then it decreased as a result of structural phase transformations.

  13. Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Bobzin, Kirsten; Zhao, Lidong; Schlaefer, Thomas; Warda, Thomas

    2011-06-01

    High-energy ball milling is an effective method to produce nanocrystalline oxides. In this study, a conventional ZrO2-7%Y2O3 spray powder was ball-milled to produce nanocrystalline powders with high levels of crystalline disorders for deposition of thermal barrier coatings. The powder was milled both with 100Cr6 steel balls and with ZrO2-3%Y2O3 ceramic balls as grinding media. The milling time was varied in order to investigate the effect of the milling time on the crystallite size. The powders were investigated in terms of their crystallite sizes and morphologies by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that under given milling conditions the powder was already nanostructured after 40 min milling. The crystallite size decreased significantly with increasing milling time within first 120 min. After that, a further increase of milling time did not lead to a significant reduction of the crystallite size. Ball-milling led to lattice microstrains. Milling with the steel balls resulted in finer nano-sized crystal grains, but caused the contamination of the powder. The nano-sized crystal grains coarsened during the heat-treatment at 1250°C.

  14. Multifractal properties of ball milling dynamics

    SciTech Connect

    Budroni, M. A. Pilosu, V.; Rustici, M.; Delogu, F.

    2014-06-15

    This work focuses on the dynamics of a ball inside the reactor of a ball mill. We show that the distribution of collisions at the reactor walls exhibits multifractal properties in a wide region of the parameter space defining the geometrical characteristics of the reactor and the collision elasticity. This feature points to the presence of restricted self-organized zones of the reactor walls where the ball preferentially collides and the mechanical energy is mainly dissipated.

  15. DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, ...

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

    DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, AND ORE BIN CHUTE, LOOKING EAST NORTHEAST. CRUSHED ORE FROM THE SECONDARY ORE BIN WAS INTRODUCED INTO THE FEED TROUGH VIA A CHUTE. AS THE BALL MILL TURNED, THE ROUND SCOOP ALSO TURNED IN THE TROUGH TO CHANNEL ORE INTO THE BALL MILL. SEE CA-292-14 FOR IDENTICAL B&W NEGATIVE. - Gold Hill Mill, Warm Spring Canyon Road, Death Valley Junction, Inyo County, CA

  16. DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, ...

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

    DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, AND ORE BIN CHUTE, LOOKING EAST NORTHEAST. CRUSHED ORE FROM THE SECONDARY ORE BIN WAS INTRODUCED INTO THE FEED TROUGH VIA A CHUTE. AS THE BALL MILL TURNED, THE ROUND SCOOP ALSO TURNED IN THE TROUGH TO CHANNEL ORE INTO THE BALL MILL. SEE CA-292-20 (CT) FOR IDENTICAL COLOR TRANSPARENCY. - Gold Hill Mill, Warm Spring Canyon Road, Death Valley Junction, Inyo County, CA

  17. Synthesis of aluminum nitride powders from a plasma-assisted ball milled precursor through carbothermal reaction

    SciTech Connect

    Liu, Zhi-jie; Dai, Le-yang; Yang, De-zheng; Wang, Sen; Zhang, Bao-jian; Wang, Wen-chun; Cheng, Tie-han

    2015-01-15

    Highlights: • A novel and high efficiency synthesizing AlN powders method combining mechanical ball milling and DBDP has been developed. • The particle size, the crystallite size, the lattice distortion, the morphology of Al{sub 2}O{sub 3} powders, and the AlN conversion rate are investigated and compared under the ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP. • The ball milled Al{sub 2}O{sub 3} powders with DBDP have small spherical structure morphology with very fine particles size and high specific surface area, which result in a higher chemical efficiency and a higher AlN conversion rate at lower thermal temperature. - Abstract: In this paper, aluminum nitride (AlN) powers have been produced with a novel and high efficiency method by thermal annealing at 1100–1600 °C of alumina (Al{sub 2}O{sub 3}) powders which were previously ball milled for various time up to 40 h with and without the assistant of dielectric barrier discharge plasma (DBDP). The ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP and the corresponding synthesized AlN powers are characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. From the characteristics of the ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP, it can be seen that the ball milled Al{sub 2}O{sub 3} powders with DBDP have small spherical structure morphology with very fine particles size and high specific surface area, which result in a higher chemical efficiency and a higher AlN conversion rate at lower thermal temperature. Meanwhile, the synthesized AlN powders can be known as hexagonal AlN with fine crystal morphology and irregular lump-like structure, and have uniform distribution with the average particle size of about between 500 nm and 1000 nm. This provides an important method for fabricating ultra fine powders and synthesizing nitrogen compounds.

  18. DETAIL OF CYCLONE CLASSIFIER, WITH MARCY NO. 86 BALL MILL ...

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

    DETAIL OF CYCLONE CLASSIFIER, WITH MARCY NO. 86 BALL MILL BELOW AND BEHIND IT. STRAIGHT HORIZONTAL PIPE IS SLIME FEED FROM ROD MILL. PIPE OUT TOP OF CYCLONE AND CURVING AT LOWER RIGHT CARRIED FINELY GROUND SLIME TO FLOTATION CONDITIONER TANK. PIPE NOT VISIBLE OUT BOTTOM OF CYCLONE CONVEYED COARSER SLIME TO BALL MILL. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  19. Magnetic and Magnetocaloric Properties of High-Energy Ball-Milled Nanocrystalline CeMn2Ge2 Compound

    NASA Astrophysics Data System (ADS)

    Kaya, Melike; Dincer, Ilker; Akturk, Selcuk; Elerman, Yalcin

    2016-07-01

    CeMn2Ge2 nanopowders have been obtained by high-energy ball milling for 5 and 10 hours from bulk compound to investigate the effect of milling time on magnetic and magnetocaloric properties. CeMn2Ge2 nanopowders have been characterized by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, and magnetization measurements. The average grain size of the nanoparticles from XRD measurements is about 12.2 and 8 nm for 5-hour and 10-hour ball-milled samples, respectively. The investigations reveal that magnetic entropy change (∆S m) can be altered by changing the particle size of the compound. Maximum ∆S m is -2.45 and -1.30 J kg-1 K-1 for the 5- and 10-hour ball-milled nanopowders, respectively.

  20. Nano-subgrain Strengthening in Ball-milled Iron

    SciTech Connect

    Lesuer, D R; Syn, C K; Sherby, O D

    2006-03-23

    The strength and deformation behavior of ball-milled, iron-base materials containing nano-scale subgrains have been evaluated. As reported by several authors, nanosubgrains form during the early stages of ball milling as a result of severe plastic deformation inherent in the ball milling process. The strength for these nano-scale subgrains are compared with the strength of larger-scale subgrains in iron and iron-base alloys produced by traditional mechanical working. The data covers over 2 orders of magnitude in subgrain size (from 30 nm to 6 {micro}m) and shows a continuous pattern of behavior. For all materials studied, the strength varied as {lambda}{sup -1}, where {lambda} is the subgrain size. Strengthening from subgrains was found to breakdown at a much smaller subgrain size than strengthening from grains. In addition, the ball-milled materials showed significant strengthening contributions from nano-scale oxide particles. Shear bands are developed during testing of ball-milled materials containing ultra-fine subgrains. A model for shear band development in nano-scale subgrains during deformation has also been developed. The model predicts a strain state of uniaxial compression in the shear band with a strain of -1.24. Subgrains are shown to offer the opportunity for high strength and good work hardening with the absence of yield point behavior.

  1. Powder properties of hydrogenated ball-milled graphite

    SciTech Connect

    Zhang, Y.; Wedderburn, J.; Harris, R.; Book, D.

    2014-12-15

    Ball milling is an effective way of producing defective and nanostructured graphite. In this work, the hydrogen storage properties of graphite, ball-milled in a tungsten carbide milling pot under 3 bar hydrogen for various times (0–40 h), were investigated by TGA-Mass Spectrometry, XRD, SEM and laser diffraction particle size analysis. For the conditions used in this study, 10 h is the optimum milling time resulting in desorption of 5.5 wt% hydrogen upon heating under argon to 990 °C. After milling for 40 h, the graphite became significantly more disordered, and the amount of desorbed hydrogen decreased. After milling up to 10 h, the BET surface area increased while particle size decreased; however, there is no apparent correlation between these parameters, and the hydrogen storage properties of the hydrogenated ball-milled graphite.

  2. 6. FF coal pulverizer (ball mill inside). GG building in ...

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

    6. FF coal pulverizer (ball mill inside). GG building in background did preliminary crushing; pulverizer to left, coal conveyor and air cleaning towers to right; conveyor on left brought crushed coal to FF. Looking north/northeast - Rouge Steel Company, 3001 Miller Road, Dearborn, MI

  3. Generation of drugs coated iron nanoparticles through high energy ball milling

    NASA Astrophysics Data System (ADS)

    Radhika Devi, A.; Chelvane, J. A.; Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh; Murty, B. S.

    2014-03-01

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  4. Generation of drugs coated iron nanoparticles through high energy ball milling

    SciTech Connect

    Radhika Devi, A.; Murty, B. S.; Chelvane, J. A.; Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh

    2014-03-28

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  5. Ball-milled sulfur-doped graphene materials contain metallic impurities originating from ball-milling apparatus: their influence on the catalytic properties.

    PubMed

    Chua, Chun Kiang; Sofer, Zdeněk; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2016-07-21

    Graphene materials have found applications in a wide range of devices over the past decade. In order to meet the demand for graphene materials, various synthesis methods are constantly being improved or invented. Ball-milling of graphite to obtain graphene materials is one of the many versatile methods to easily obtain bulk quantities. In this work, we show that the graphene materials produced by ball-milling are spontaneously contaminated with metallic impurities originating from the grinding bowls and balls. Ball-milled sulfur-doped graphene materials obtained from two types of ball-milling apparatus, specifically made up of stainless steel and zirconium dioxide, were investigated. Zirconium dioxide-based ball-milled sulfur-doped graphene materials contain a drastically lower amount of metallic impurities than stainless steel-based ball-milled sulfur-doped graphene materials. The presence of metallic impurities is demonstrated by their catalytic effects toward the electrochemical catalysis of hydrazine and cumene hydroperoxide. The general impression toward ball-milling of graphite as a versatile method for the bulk production of 'metal-free' graphene materials without the need for post-processing and the selection of ball-milling tools should be cautioned. These findings would have wide-reaching implications for graphene research. PMID:27314607

  6. Mechanochemical destruction of mirex co-ground with iron and quartz in a planetary ball mill.

    PubMed

    Yu, Yunfei; Huang, Jun; Zhang, Wang; Zhang, Kunlun; Deng, Shubo; Yu, Gang

    2013-02-01

    Mechanochemical destruction (MCD) has been recognized as a promising non-combustion technology for the disposal of obsolete pesticides belonging to the persistent organic pollutants (POPs). Mirex, a termiticide ever used for many years in China, was ball milled in the presence of various reagent(s) in a planetary ball mill at room temperature to investigate the destruction efficiency. The ground samples were characterized and analyzed by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, gas chromatography (GC), and ion chromatography (Martins, Bicego et al.). Under the same conditions of mill rotary rate and charge ratio, the mixture of iron powder and quartz sand (Fe/SiO(2)) was found best in promoting the mirex destruction. Mirex was completed destroyed after 2 h grinding at a charge ratio of 36:1 (reagent/mirex, m/m) and a mill rotation speed of 550 rpm. No organic compound was detected by GC/μECD screening. The yield of water-soluble chlorine determined by ion chromatography (Martins, Bicego et al.) in the final residue accounted for 90.7% of chlorine in the original mirex, which indicated a nearly complete dechlorination. Signals of both graphite and amorphous carbon were found in the Raman spectra of the co-ground powder samples. With the main final degradation products of water soluble Cl and carbon, the mechanism of the mechanochemical destruction approach should be dechlorination followed by the carbonization. PMID:23186893

  7. Effects and mechanism of ball milling on torrefaction of pine sawdust.

    PubMed

    Gong, Chunxiao; Huang, Jing; Feng, Chen; Wang, Guanghui; Tabil, Lope; Wang, Decheng

    2016-08-01

    The effects and mechanism of ball milling on the torrefaction process were studied. Ball- and hammer-milled (screen size 1mm) pine sawdust samples were torrefied at three temperatures (230, 260, and 290°C) and two durations (30 and 60min) to investigate into their torrefaction behavior and physicochemical properties. The results showed that, under identical torrefaction conditions, torrefied ball-milled pine sawdust had a higher carbon content and fixed carbon, and lower hydrogen and oxygen contents than torrefied hammer-milled pine sawdust. Torrefied ball-milled pine sawdust produced lower mass and energy yields, but higher heating values than torrefied hammer-milled pine sawdust. Ball milling destroyed the crystalline structure of cellulose and thus reduced the thermal stability of hemicellulose, cellulose, and lignin, causing them to degrade at relatively lower temperatures. In conclusion, biomass pretreated with a combination of ball milling and torrefaction has the potential to produce an alternative fuel to coal. PMID:27136611

  8. Ball-milled CuPc/TiO{sub 2} hybrid nanocomposite and its photocatalytic degradation of aqueous Rhodamine B

    SciTech Connect

    Mekprasart, W.; Vittayakorn, N.; Pecharapa, W.

    2012-11-15

    Graphical abstract: This work reports on the synthesis of hybrid composites of titanium dioxide and copper phthalocyanine via ball-milling assisted process in combination with mechanical mixing process. Their structural properties and photocatalytic degradation of aqueous RhB were investigated. The significant enhancement of the photocatalytic performance of the composite may be related to the charge recombination suppression guiding to the increase of free functional radicals participated in degradation process. Highlights: ► CuPc/TiO{sub 2} nanocomposite was synthesized by ball-milling assisted process and mechanical mixing method. ► Ball milling process can reduce CuPc size and assist the formation of well-dispersed composite. ► Loaded CuPc has inconsiderable influence on basic crystal structure of TiO{sub 2} matrix. ► The optical absorption properties of TiO{sub 2} in UV and visible light is improved with the existence of CuPc. ► CuPc/TiO{sub 2} nanocomposite can efficiently heighten the catalytic performance of TiO{sub 2} in the photodegradation of RhB. -- Abstract: Hybrid composites of titanium dioxide and copper phthalocyanine were synthesized by ball-milling assisted process in combination with mechanically stirring method. Structural properties of as-synthesized composites were characterized by X-ray diffraction (XRD), X-ray absorption fine structure (XANES) and scanning electron microscope (SEM). The optical absorbance of as-prepared composites and their photocatalytic activities were investigated by UV–vis spectroscopy. XRD and XANES results confirm that CuPc/TiO{sub 2} nanocomposite is still in the same structure of TiO{sub 2} and CuPc. SEM result reveals that the decreasing particle size of ball-milled CuPc has good dispersion on the surface of TiO{sub 2}. Absorptivity in UV region of the composites is heightened and shifted to visible light due to strong absorbance in blue-green spectrum of CuPc. The photocatalytic degradation of Rhodamine

  9. ELECTROMAGNETIC MICROWAVE PROPERTIES OF Fe82B17Cu1 BALL MILLED ALLOY

    NASA Astrophysics Data System (ADS)

    Tian, N.; Fan, X. D.; Wang, J. W.; You, C. Y.; Lu, Z. X.; Ge, L. L.

    2013-07-01

    High saturation magnetization and magnetic anisotropy are helpful for getting a high frequency electromagnetic microwave absorption performance. The α-Fe possesses a high saturation magnetization. Fe-B phases exhibit a relatively higher magnetic anisotropy and higher resistivity than α-Fe simultaneously. In this work, we made nanocrystalline powders of Fe82B17Cu1, mainly consisting of α-Fe and Fe2B phases, by ball milling and post-annealing. Electromagnetic microwave characterization shows that Fe82B17Cu1 powders possess a relative high permeability and considerable permittivity. Due to a good electromagnetic impedance matching, a good electromagnetic microwave absorption property (RL < -35 dB) has been achieved at 3.6 GHz. The experimental frequency and the matching thickness are coincident with the quarter wavelength matching condition.

  10. Influence of milling time on fineness of Centella Asiatica particle size produced using planetary ball mill

    NASA Astrophysics Data System (ADS)

    Borhan, M. Z.; Ahmad, R.; Rusop, M.; Abdullah, S.

    2012-11-01

    Centella Asiatica (C. Asiatica)contains asiaticoside as bioactive constituent which can be potentially used in skin healing process. Unfortunately, the normal powders are difficult to be absorbed by the body effectively. In order to improve the value of use, nano C. Asiatica powder was prepared. The influence of milling time was carried out at 0.5, 2, 4, 6, 8 hours and 10 hours. The effect of ball milling at different times was characterized using particles size analysis and FTIR Spectroscopy. The fineness of ground product was evaluated by recording the z-Average (nm), undersize distribution and polydispersity index (PdI). The results show that the smallest size particles by mean is 233 nm while FTIR spectra shows that there is no changing in the major component in the C. Asiatica powders with milling time.

  11. Athermal character of the solid state amorphization of lactose induced by ball milling

    NASA Astrophysics Data System (ADS)

    Willart, J. F.; Caron, V.; Lefort, R.; Danède, F.; Prévost, D.; Descamps, M.

    2004-12-01

    In this paper, we report the possibility to reach pure glassy amorphous lactose by ball milling of crystalline α lactose under a dry nitrogen atmosphere. This route to the glassy state is found to be free of mutarotation towards the anomer β while this mutarotation is unavoidable using the usual thermal route, i.e. the quench of the liquid. This result definitely makes the 'local quench melting' hypothesis unsuitable to account for amorphization by ball milling.

  12. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Burkhart, L.; Tampy, G.; Pollard, J.

    1988-06-01

    Techniques were studied to alter and control the surface chemistry of ultrafine coal and mineral particles during comminution in a stirred ball mill to enhance liberation and subsequent physical separation. Three-phase (kerosene-liquid-solid) contact angle measurements were taken with kerosene as the oil phase; with acidic, basic, neutral, and sodium dithionite solutions constituting the aqueous phase, and organic-rich and mineral-rich fractions of Upper Freeport coal constituting the solid phase. The hydrophobic/hydrophilic effect of the aqueous solutions on the organic-rich and mineral-rich fractions was compared to the results of microbubble froth flotation. Continuous microbubble column flotation experiments were also conducted and the effect of several variables investigated. In general, slow feed rates, high frother concentration and high frit pressure yielded better results. The use of oxone, a peroxygen triple salt, as a chemical reagent during grinding and pretreatment prior to beneficiation, was explored. The acidic surface functional oxygen groups were studied to more fully understand the changes on coal samples affected by chemical pretreatment. 6 refs., 3 figs., 7 tabs.

  13. Raman spectroscopy of ball-milled TiO 2

    NASA Astrophysics Data System (ADS)

    Gajović, A.; Stubičar, M.; Ivanda, M.; Furić, K.

    2001-05-01

    Raman spectroscopy was applied to study structural and dimensional changes during high-energy ball milling of TiO 2 anatase. Milling was performed for up to 10 h using two different sets of grinding tools (wolfram carbide (WC) and agate). The diminution of the TiO 2 particle to nanometric size was monitoring by low-frequency Raman spectroscopy. The nanometric sizes were confirmed by transmission electron microscopy (TEM). After short milling time by WC the bands of high-pressure TiO 2 II phase (α-PbO 2 structure) were detected in Raman spectrum. Prolonged milling time was needed for transformation to rutil. When milling was performed by agate, the time necessary for both phase transitions was longer, presumably because of lower ball-to-powder weight ratio. The low-frequency Raman band of the prolonged milled samples was broad, which suggests the wide dispersion in nano-particle dimensions. The position of the low-frequency band in longer-milled samples indicated dimensions smaller than 20 nm, since the diameter of the particle is inversely proportional to the low-frequency mode of the spherical particles. These results were in agreement with the TEM results.

  14. Response to Thermal Exposure of Ball-Milled Aluminum-Borax Powder Blends

    NASA Astrophysics Data System (ADS)

    Birol, Yucel

    2013-04-01

    Aluminum-borax powder mixtures were ball milled and heated above 873 K (600 °C) to produce Al-B master alloys. Ball-milled powder blends reveal interpenetrating layers of deformed aluminum and borax grains that are increasingly refined with increasing milling time. Thermal exposure of the ball-milled powder blends facilitates a series of thermite reactions between these layers. Borax, dehydrated during heating, is reduced by Al, and B thus generated reacts with excess Al to produce AlB2 particles dispersed across the aluminum grains starting at 873 K (600 °C). AlB2 particles start to form along the interface of the aluminum and borax layers. Once nucleated, these particles grow readily to become hexagonal-shaped crystals that traverse the aluminum grains with increasing temperatures as evidenced by the increase in the size as well as in the number of the AlB2 particles. Ball milling for 1 hour suffices to achieve a thermite reaction between borax and aluminum. Ball milling further does not impact the response of the powder blend to thermal exposure. The nucleation-reaction sites are multiplied, however, with increasing milling time and thus insure a higher number of smaller AlB2 particles. The size of the AlB2 platelets may be adjusted with the ball milling time.

  15. Crystal structure of ball-milled mixture of sodium chloride and magnesium chloride-ethanol adduct

    SciTech Connect

    Jiang Xue; Tian Xiuzhi; Fan Zhiqiang

    2008-02-05

    NaCl doped MgCl{sub 2}.nEtOH adducts were prepared by ball-milling MgCl{sub 2}.2.5EtOH with NaCl. Both the ball-milled MgCl{sub 2}.nEtOH/NaCl mixture and pure MgCl{sub 2}.2.5EtOH adducts were analyzed by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetry (TG) and differencial scanning calorimetry (DSC). A simple MgCl{sub 2}.nEtOH/NaCl mixture without ball-milling treatment was also studied for comparison. Two kinds of mixed crystals, Na{sub 2}MgCl{sub 4} and NaMgCl{sub 3}, were found to be formed in a ball-milled mixture that contained 16 mol.% NaCl. TG and DSC analysis of the samples also provided indirect evidences supporting the presence of the mixed crystals in the ball-milled mixture. Adding certain amounts of NaCl in MgCl{sub 2}.2.5EtOH adduct, either by co-milling or by simple mixing, greatly increased the thermal stability of the adduct, but thermal decomposition behaviour of the ball-milled mixture was still different from that of a simple mixture.

  16. On the amorphization behavior and hydrogenation performance of high-energy ball-milled Mg{sub 2}Ni alloys

    SciTech Connect

    Kou, Hongchao; Hou, Xiaojiang; Zhang, Tiebang Hu, Rui; Li, Jinshan; Xue, Xiangyi

    2013-06-15

    Amorphous Mg{sub 2}Ni alloy was prepared by high energy ball-milling starting with polycrystalline Mg{sub 2}Ni which was prepared with the help of a metallurgy method by using a SPEX 8000D mill. The microstructural and phase structure characterization of the prepared materials was performed via scanning electron microscopy, transition electron microscope and X-ray diffraction. The thermal stabilities were investigated by differential scanning calorimetry. The apparent activation energies were determined by means of the Kissinger method. The first and second crystallization reactions take place at ∼ 255 °C and ∼ 410 °C, and the corresponding activation energy of crystallization is E{sub a1} = 276.9 and E{sub a2} = 382.4 kJ/mol, respectively. At 3 MPa hydrogen pressure and 250 °C, the hydrogen absorption capacities of crystalline, partially and fully amorphous Mg{sub 2}Ni alloy are 2.0 wt.%, 3.2 wt.% and 3.5 wt.% within 30 min, respectively. - Graphical Abstract: We mainly focus on the amorphization behavior of crystalline Mg{sub 2}Ni alloy in the high energy ball-milling process and the crystallization behavior of the amorphous Mg{sub 2}Ni alloy in a follow-up heating process. The relationship of milling, microstructure and hydrogenation properties is established and explained by models. - Highlights: • Amorphous Mg{sub 2}Ni has been obtained by high energy ball milling the as-cast alloy. • The amorphization behavior of polycrystalline Mg{sub 2}Ni is presented. • The crystallization behavior of the amorphous Mg{sub 2}Ni alloy is illustrated. • Establish the relationship of milling, microstructure and hydrogenation properties.

  17. Impact of high energy ball milling on the nanostructure of magnetite–graphite and magnetite–graphite–molybdenum disulphide blends

    SciTech Connect

    Österle, W.; Orts-Gil, G.; Gross, T.; Deutsch, C.; Hinrichs, R.; Vasconcellos, M.A.Z.; Zoz, H.; Yigit, D.; Sun, X.

    2013-12-15

    Different, partly complementary and partly redundant characterization methods were applied to study the transition of magnetite, graphite and MoS{sub 2} powders to mechanically alloyed nanostructures. The applied methods were: Transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), Raman spectroscopy (RS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The main objective was to prepare a model material providing the essential features of a typical tribofilm forming during automotive braking, and to assess the impact of different constituents on sliding behaviour and friction level. Irrespective of the initial grain size, the raw materials were transferred to a nanocrystalline structure and mixed on a nanoscopic scale during high energy ball milling. Whereas magnetite remained almost unchanged, graphite and molybdenum disulphide were transformed to a nanocrystalline and highly disordered structure. The observed increase of the coefficient of friction was attributed to a loss of lubricity of the latter ingredient due to this transformation and subsequent oxidation. - Highlights: • Characterization of microstructural changes induced by high energy ball milling • Assessment of the potential of different characterization methods • Impact of mechanical alloying on tribological performance revealed by tests • Preparation of an artificial third body resembling the one formed during braking.

  18. Effects of ball milling and sintering on alumina and alumina-boron compounds

    NASA Astrophysics Data System (ADS)

    Cross, Thomas

    Alumina has a wide variety of applications, but the processing of alumina based materials can be costly. Mechanically milling alumina has been shown to enhance the sintering properties while decreasing the sintering temperature. Additions of boron have also proven to increase sintering properties of alumina. These two processes, mechanical milling and boron additions, will be combined to test the sintering properties and determine if they are improved upon even further compared to the individual processes. Multiple samples of pure alumina, 0.2 weight percent boron, and 1.0 weight percent boron are batched and processed in a ball mill for different time intervals. These samples are then characterized to observe the structure and properties of the samples after milling but before sintering. Pellets are dry pressed from the milled powders, sintered at 1200°C for one to 10 hours, and characterized to determine the impact of processing. X-ray diffractometry (XRD) was used on each sample to determine crystallite size and lattice parameters at different stages throughout the experiment. XRD was also used to identify any samples with an aluminum borate phase. Scanning electron microscopy (SEM) was used to observe the powder and pellet morphology and to measure bulk chemical composition. Samples were sputter coated with an Au-Pd coating observed in the SEM to characterize the topography as a function of variables such as milling time, boron composition, and sintering time. Additionally, porosity and change in diameter were measured to track the sintering process. Milling sample for longer periods of time would be unnecessary due to the crystallite size leveling off between 10 and 12 hours of milling time. Samples of alumina with 0.2 weight percent boron prove to have very little effect on the sintering properties. At 1.0 weight percent boron, there are changes in diffraction patterns and topography after being sintered for one hour. The porosities of all of the sintered

  19. Synthesis of Nano-Size AlN Powders by Carbothermal Reduction from Plasma-Assisted Ball Milling Precursor

    NASA Astrophysics Data System (ADS)

    Liu, Zhijie; Wang, Wenchun; Yang, Dezheng; Wang, Sen; Dai, Leyang

    2016-07-01

    Nano-size aluminum nitride (AlN) powders have been successfully synthesized with a high efficiency method through annealing from milling assisted by discharge plasma (p-milling) alumina (Al2O3) precursors. The characterization of the p-milling Al2O3 powders and the synthesized AlN are investigated. Compared to conventional ball milling (c-milling), it can be found that the precursors by p-milling have a finer grain size with a higher specific surface area, which lead to a faster reaction efficiency and higher conversion to AlN at lower temperatures. The activation energy of p-milling Al2O3 is found to be 371.5 kJ/mol, a value that is much less than the reported value of the unmilled and the conventional milled Al2O3. Meanwhile, the synthesized AlN powders have unique features, such as an irregular lamp-like morphology with uniform particle distribution and fine average particle size. The results are attributed to the unique synergistic effect of p-milling, which is the effect of deformation, fracture, and cold welding of Al2O3 powders resulting from ball milling, that will be enhanced due to the introduction of discharge plasma. supported by National Natural Science Foundation of China (No. 51177008)

  20. The effects of attrition and ball milling on the properties of magnesium diboride

    NASA Astrophysics Data System (ADS)

    Dancer, C. E. J.; Prabhakaran, D.; Crossley, A.; Todd, R. I.; Grovenor, C. R. M.

    2010-06-01

    Commercially produced magnesium diboride powder was modified by attrition milling and ball milling in propan-2-ol for various durations. These powders were characterized by means of particle size distribution measurements using laser diffraction, impurity analysis using x-ray diffraction, energy dispersive spectroscopy and x-ray photoelectron spectroscopy, and scanning electron microscopy, and were then used to produce magnesium diboride samples through pressureless heat treatment at peak temperatures up to 1100 °C. X-ray diffraction, scanning electron microscopy, Vickers hardness measurements, and density measurements using the Archimedes method were used to characterize the properties of the samples, and a determination of their superconducting properties using the magnetization method was carried out. Magnesium diboride produced from powder milled under certain conditions had a higher Jc, mag than samples produced from as-purchased powder, but the relationship between the milling duration or energy and the superconducting performance is a complex one, affected by both the particle size and the impurity content of the starting powder.

  1. Preparation of magnesium ferrite nanoparticles by ultrasonic wave-assisted aqueous solution ball milling.

    PubMed

    Chen, Ding; Li, Dian-yi; Zhang, Ying-zhe; Kang, Zhi-tao

    2013-11-01

    Magnesium ferrite, MgFe2O4 nanoparticles with high saturation magnetization were successfully synthesized using ultrasonic wave-assisted ball milling. In this study, the raw materials were 4MgCO3·Mg(OH)2·5H2O and Fe2O3 powders and the grinding media was stainless steel ball. The average particle diameter of the product MgFe2O4 powders was 20 nm and the saturation magnetization of them reached 54.8 emu/g. The different results of aqueous solution ball milling with and without ultrasonic wave revealed that it was the coupling effect of ultrasonic wave and mechanical force that played an important role during the synthesis of MgFe2O4. In addition, the effect of the frequency of the ultrasonic wave on the ball milling process was investigated. PMID:23622867

  2. Structural and magnetic stability of high energy ball milled Co2MnSi

    NASA Astrophysics Data System (ADS)

    Vinesh, A.; Sudheesh, V. D.; Sebastian, Varkey; Lakshmi, N.; Venugopalan, K.

    2015-07-01

    Structural and magnetic properties of ball milled Co2MnSi have been studied and compared with that of ordered bulk sample. The milled sample (with average size determined using the Williamson-Hall method) shows that the chemical ordering for this sample is very stable and is little effected by high energy ball milling. However, the reduction in the saturation magnetic moment of the milled sample shows that there is spin disordering induced on ball milling - attributable to the formation of a magnetically dead layer at the surface of the nano-sized samples. The ordered sample (unmilled) has a saturation moment value of 4.4 μB per formula unit at room temperature and is in agreement with the prediction of Slater Pauling curve. On milling it reduces to ~3 μB per formula unit at room temperature with an accompanying increase in the coercivity, retentivity and squareness factor.

  3. Effective high-energy ball milling in air of Fe65Co35 alloys

    NASA Astrophysics Data System (ADS)

    Sirvent, P.; Berganza, E.; Aragón, A. M.; Bollero, A.; Moure, A.; García-Hernández, M.; Marín, P.; Fernández, J. F.; Quesada, A.

    2014-05-01

    Fe65Co35 alloys are technologically relevant, especially in magnetic storage and composite permanent magnets, due to the fact that they present higher saturation magnetization per volume than any other material. Out of the various approaches undertaken for its production, mechanical ball milling remains the most common and efficient method, especially considering the large industrial scale of the applications. With the development of cost-efficient processing in mind, the influence of performing the synthesis of the FeCo alloys in air instead of the standard argon atmosphere is studied. The structural and magnetic characterization, along with the study of the oxygen content of the samples, proves that synthesizing FeCo alloys in air produce materials with nearly identical magnetic performance as their argon-milled counterpart, with the oxidation extent of the materials consisting almost exclusively of the oxide passivating layer located at the surface. In addition, no aging effect was observed in the saturation magnetization up to 6 months. It is concluded that the use of argon atmospheres, desiccators and/or glove boxes may be entirely removed from the process without affecting the magnetic properties.

  4. Phase Transformation and Magnetic Property of Ni-Mn-Ga Powders Prepared by Dry Ball Milling

    NASA Astrophysics Data System (ADS)

    Tian, B.; Chen, F.; Tong, Y. X.; Li, L.; Zheng, Y. F.

    2012-12-01

    This study investigated the phase transformations and magnetic properties of Ni-Mn-Ga alloy powders prepared by dry ball milling in argon atmosphere. The Fe and Cr elements were found to be introduced in the alloy after ball milling, which should result from the severe collision and friction among the particles, balls, and vial. The x-ray diffraction result indicated that the Fe and Cr elements should have alloyed with the Ni-Mn-Ga matrix. The martensitic transformation temperature and Curie temperature of the 800 °C annealed powders decreased by ~33 °C and increased by ~28 °C, respectively, as compared to that of the bulk alloy. The comprehensive effect of the changing of valence electron concentration of the alloy due to the introduction of Fe and Cr and the grain refinement of the alloy caused by ball milling should be responsible for the reduction of martensitic transformation temperature. The saturation magnetization of the 800 °C annealed powders became larger (~5 emu/g) than that of the bulk alloy. The enhancement of magnetic properties, such as the increase of Curie temperature and enhancement of saturation magnetization of the annealed Ni-Mn-Ga powders, should be attributed to the increase of magnetic exchange caused by introduction of Fe in the alloy. The contaminations of Fe and Cr elements emerging from the dry ball milling process changed the phase transformation and magnetic properties of the Ni-Mn-Ga alloy. Therefore, the dry ball milling process is difficult to control the contamination from the milling medium and not suitable to prepare Ni-Mn-Ga powders. On the contrary, the wet ball milling method under liquid medium should be a better method to prevent the contamination and fabricate pure Ni-Mn-Ga ferromagnetic shape memory alloy powders.

  5. Effects of ball-milling on PLGA polymer and its implication on lansoprazole-loaded nanoparticles

    PubMed Central

    Shabir, Anjumn; Alhusban, Farhan; Perrie, Yvonne; Mohammed, Afzal R.

    2011-01-01

    PLGA is a biodegradable polymer utilised widely in pharmaceutical research for the encapsulation of a wide range of drugs as nano particulate systems. This study investigates the impact of rotary ball milling on the physical properties of PLGA and its influence on nanoparticle formation prepared using the solvent displacement technique. By applying mechanical stress to the polymer and altering its physical appearance and molecular weight, the loading of lansoprazole within the nanoparticles was increased to 96%, with a reduction in particle size. The results indicate that rotary ball milling significantly reduces particle size, increases lansoprazole loading and improves the release profile for lansoprazole loaded PLGA nanoparticles PMID:24826005

  6. Nitrogen-doped graphene by ball-milling graphite with melamine for energy conversion and storage

    NASA Astrophysics Data System (ADS)

    Xue, Yuhua; Chen, Hao; Qu, Jia; Dai, Liming

    2015-12-01

    N-doped graphene was prepared by ball milling of graphite with melamine. It was found that ball-milling reduced the size of graphite particles from 30 to 1 μm and facilitated the exfoliation of the resultant small particles into few-layer N-doped graphene nanosheets under ultrasonication. The as-prepared N-doped graphene nanoplatelets (NGnPs) exhibited a nitrogen content as high as 11.4 at.%, making them attractive as efficient electrode materials in supercapacitors for energy storage and as highly-active metal-free catalysts for oxygen reduction in fuel cells for energy conversion.

  7. Deformation mechanisms at Different grain sizes in a cryogenically ball-milled Al-Mg alloy.

    SciTech Connect

    Liao, Xiaozhou; Huang, J.; Zhu, Y. T.; Zhou, F.; Lavernia, Enrique J.

    2001-01-01

    An Al-7.5 wt. % Mg alloy was ball-milled in liquid N2 for eight hours and its microstructures were investigated using transmission electron microscopy. Electron diffraction confirmed that the resulting powder is a supersaturated Al-Mg solid solution with a face-centered cubic structure. Three nanostructures with different grain size ranges and shapes were observed and the deformation mechanisms in these structures were found to be different. The reasons for the different deformation mechanisms were discussed. Keywords: Aluminum alloy; Cryogenic ball milling; Transmission electron microscopy; Microstructure.

  8. Factors influencing the ball milling of Si3N4 in water

    NASA Technical Reports Server (NTRS)

    Freedman, M. R.; Kiser, J. D.; Herbell, T. P.

    1985-01-01

    A statistical study of the ball milling of Si3N4 powder in Si3N4 hardware was undertaken to understand how the resulting increase in specific surface area is related to solids loading and mill speed. An attempt was made to optimize milling conditions. The degree of communication was more dependent upon solids loading than mill speed. A practical grinding limit between 0.5 and 0.75 microns was achieved in 144 hr independent of solids loading. Ball mill wear and media wear were independent of both solids loading and mill speed.

  9. Structural and microstructural changes in monoclinic ZrO{sub 2} during the ball-milling with stainless steel assembly

    SciTech Connect

    Stefanic, G. . E-mail: stefanic@irb.hr; Music, S.; Gajovic, A.

    2006-04-13

    High-energy ball-milling of monoclinic ZrO{sub 2} was performed in air using the planetary ball mill with a stainless steel milling assembly. Structural and microstructural changes during the ball-milling were monitored using X-ray powder diffraction, Raman spectroscopy, Moessbauer spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectrometry. The results of line broadening analysis indicated a decrease in the crystallite size and an increase in the microstrains with the ball-milling time increased up to {approx}150 min. The results of quantitative phase analysis indicated the presence of a very small amount of tetragonal ZrO{sub 2} phase in this early stage of ball-milling. The onset of m-ZrO{sub 2} {sup {yields}} t-ZrO{sub 2} transition occurred between 10 and 15 h of ball-milling, which resulted in a complete transition after 20 h of ball-milling. Further ball-milling caused a decrease of the t-ZrO{sub 2} lattice parameters followed by a probable transition into c-ZrO{sub 2}. It was concluded that the stabilization of t- and c-ZrO{sub 2} polymorphs at RT can be attributed to the incorporation of aliovalent cations (Fe{sup 2+}, Fe{sup 3+} and Cr{sup 3+}) introduced into the sample due to the wear and oxidation of the milling media.

  10. The effect of ball milling and rehydration on powdered mixtures of hydrocolloids.

    PubMed

    Abbaszadeh, A; MacNaughtan, W; Foster, T J

    2014-02-15

    In many applications, particularly in food related work, it is assumed that ball milling merely serves as a means of reducing crystallinity by the steady attrition of crystals. In this work mixtures of cellulose with other biopolymers have been co-ball milled in the dry state typically at moisture contents of <12% (w/w) and the effects of recrystallizing these mixtures studied. We have found that recystallizing the mixtures under a humid (97%RH) atmosphere increases the crystallinity of the cellulose fraction in a fashion governed by the other hydrocolloid present in the mixture. Some of the measured effects occur during ball milling of the dry powders. A relative method of fitting mixtures of type I and type II cellulose is described. Progressive transition between these forms with time was discovered for eucalyptus and microcrystalline cellulose at 97%RH. Locust bean gum (LBG) appeared to exert a protective effect on both eucalyptus and microcrystalline cellulose against the destruction of crystallinity by ball milling. For eucalyptus cellulose high levels of type I were produced during recrystallization with LBG under humid conditions. Both cellulose samples crystallized in the type I form in the presence of LBG whereas type II was produced in the presence of other hydrocolloids. Possible mechanisms for these unusual observations are proposed. PMID:24507372

  11. Ball milling pretreatment of oil palm biomass for enhancing enzymatic hydrolysis.

    PubMed

    Zakaria, Mohd Rafein; Fujimoto, Shinji; Hirata, Satoshi; Hassan, Mohd Ali

    2014-08-01

    Oil palm biomass, namely empty fruit bunch and frond fiber, were pretreated using a planetary ball mill. Particle sizes and crystallinity index values of the oil palm biomass were significantly reduced with extended ball mill processing time. The treatment efficiency was evaluated by the generation of glucose, xylose, and total sugar conversion yields from the pretreatment process compared to the amount of sugars from raw materials. Glucose and xylose contents were determined using high-performance liquid chromatography. An increasing trend in glucose and xylose yield as well as total sugar conversion yield was observed with decreasing particle size and crystallinity index. Oil palm frond fiber exhibited the best material yields using ball milling pretreatment with generated glucose, xylose, and total sugar conversion yields of 87.0, 81.6, and 85.4%, respectively. In contrast, oil palm empty fruit bunch afforded glucose and xylose of 70.0 and 82.3%, respectively. The results obtained in this study showed that ball mill-treated oil palm biomass is a suitable pretreatment method for high conversion of glucose and xylose. PMID:24908052

  12. Development report: ball milling of boron/calcium chromate pyrotechnic blends

    SciTech Connect

    Rogers, J.W. Jr.

    1986-07-01

    The development of an automated blending procedure for the production of 20/80 weight percent boron/calcium chromate (B/CaCrO/sub 4/) pyrotechnic is summarized chronologically in this report. The development included: (1) a blending study to assess the physical and chemical effects that various steps from previous and new blending procedures had on boron and CaCrO/sub 4/; (2) ball milling small quantities of older blends to improve firing performance and subsequent scale up to kilogram-size batches; (3) optimization of drying conditions; and, (4) blending B/CaCrO/sub 4/ from its individual constituents in a ball mill followed by drying in a Ross mixer. Extensive high and low current all-fire sensitivity testing along with electrostatic sensitivity testing indicate that compositions which are blended in a ball mill have equal or superior performance to compositions produced by previous methods; in addition, the blended compositions can be produced in a more reliable manner. These results have led to a new specification for B/CaCrO/sub 4/ production based upon the ball milling procedure. 28 refs., 9 tabs.

  13. Spectroscopic studies on the formation kinetics of SnO2 nanoparticles synthesized in a planetary ball mill

    NASA Astrophysics Data System (ADS)

    Kozma, G.; Kukovecz, Á.; Kónya, Z.

    2007-05-01

    SnO2 nanoparticles with an average diameter of 9 nm were synthesized by the mechanochemical reaction between SnCl2 and Na2CO3 in a planetary ball mill. The pressure and the temperature were continuously monitored in the milling drum and the reaction products were characterized by TEM, SEM, FT-Raman, mid-IR and far-IR spectroscopy. The pressure in the drum was found to be a highly nonlinear function of the milling time. This finding could be adequately explained on the basis of the spectroscopic evidence collected. We suggest that the speed of the mechanochemical reaction is given by a fast-slow-fast(-slow) series which is caused by the variation of the wetness of the reaction mixture during milling. The measured pressure nonlinearity is thus a direct consequence of the kinetics of the mechanochemical reaction.

  14. Magnetic and mechanical properties of Cu (75 wt%) - 316L grade stainless steels synthesized by ball milling and annealing

    NASA Astrophysics Data System (ADS)

    Mondal, Bholanath; Chabri, Sumit; Sardar, Gargi; Bhowmik, Nandagopal; Sinha, Arijit; Chattopadhyay, Partha Protim

    2015-05-01

    Elemental powders of Cu (75 wt%) and 316-stainless steel (25 wt%) has been subjected to ball milling upto 70 h followed by isothermal annealing at the temperature range of 350-750 °C for 1 h to investigate the microstructural evolution along with magnetic and mechanical properties. After 40 h of milling, the bcc Fe is almost dissolved in the solid solution of Cu but no significant change has been observed in the XRD pattern after 70 h of milling, Annealing of the alloy has resulted in precipitation of nanocrystalline bcc-Fe in Cu which triggers the soft ferromagnetic properties. The extensive mechanical characterization has been done at the microstructural scale by nanoindentation technique which demonstrates a hardening behavior of the compacted and annealed alloys due to possible precipitation of nanocrystalline bcc-Fe in Cu.

  15. Electric modulus formalism and electrical transport property of ball mill synthesized nanocrystalline Mn doped ZrO2 solid solution

    NASA Astrophysics Data System (ADS)

    Saha, S.; Nandy, A.; Meikap, A. K.; Pradhan, S. K.

    2015-12-01

    Here we report the formation of Mn doped nanocrystalline ZrO2 solid solution synthesized by high energy ball-milling method and the transport mechanism in the temperature range 298 Kcharacterization of different phases and relative phase abundances using XRD patterns. The electrical study shows the dc conductivity enhances as the doping percentage increases. Complex electric modulus study shows low frequency region approaches to ideal Debye type behaviour while the high frequency side deviates. Alternating current conductivity is found to follow the power law σ'(f,T)∝fsTn. A transformation from small polaron hopping to correlated barrier hopping has been observed from the temperature dependence frequency exponent study. The contribution of grain boundary resistance is found to be dominating over the grain resistance in the ac conduction process.

  16. Remarkable performance improvement of inexpensive ball-milled Si nanoparticles by carbon-coating for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Kasukabe, Takatoshi; Nishihara, Hirotomo; Iwamura, Shinichiroh; Kyotani, Takashi

    2016-07-01

    Si nanoparticles prepared by ball-milling (BM-Si) are expected as practical negative-electrode materials for lithium-ion batteries, but their performance is much lower than those of more expensive Si nanomaterials, such as chemical-vapor-deposition derived Si nanoparticles (CVD-Si) having a tight network structure. It is found that carbon-coating of aggregations of BM-Si forms a quasi-network structure, thereby making the performance comparable to that of CVD-Si under capacity restriction (to 1500 mAh g-1). In this case, the structural transition of BM-Si during charge/discharge cycling is characterized by the formation of a specific 'wrinkled structure', which is very similar to that formed in CVD-Si.

  17. Ball milling improves extractability and affects molecular properties of psyllium (Plantago ovata Forsk) seed husk arabinoxylan.

    PubMed

    Van Craeyveld, Valerie; Delcour, Jan A; Courtin, Christophe M

    2008-12-10

    Psyllium (Plantago ovata Forsk) seed husk (PSH) is very rich in arabinoxylan (AX). However, its high gelling capacity and the complex nature of the AX make it difficult to process. In this study, ball milling was investigated as a tool for enhancing PSH AX water extractability and molecular mass (MM). A 48 h laboratory-scale ball mill treatment under standardized optimal conditions reduced the PSH average particle size from 161 microm for the untreated sample to 6 microm. Concurrently, it increased the water-extractable AX (WE-AX) level from 13 (untreated PSH) to 90% of the total PSH AX. While the WE-AX of the untreated PSH had a peak MM of 216 kDa and an arabinose to xylose (A/X) ratio of 0.20, WE-AX fragments from ball mill-pretreated PSH had a peak MM of 22 kDa and an A/X ratio of 0.31. Ball milling further drastically reduced the intrinsic viscosity of PSH extracts and their water-holding capacity. Prolonged treatment brought almost all AX (98%) in solution and yielded WE-AX fragments with an even higher A/X ratio (0.42) and a lower peak MM (11 kDa). While impact and jet milling of PSH equally led to significant reductions in particle size, these technologies only marginally affected the water extractability of PSH AX. This implies that ball milling affects PSH particles and their constituent molecules differently than impact and jet milling. PMID:19007123

  18. Magnetic property and microstructure of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR powders

    SciTech Connect

    Li, WF; Hu, XC; Cui, BZ; Yang, JB; Han, JZ; Hadjipanayis, GC

    2013-08-01

    In this work we report the microstructure and magnetic property of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR Nd-Fe-B alloys. The average size of the particles is 283 nm, and TEM observation reveals that these particles are single crystalline. The coercivity of these particles is 6.0 kOe, which is much higher than that of the particles ball milled from sintered and hot pressed Nd-Fe-B magnets. Micromagnetic analysis shows that the coercivity degradation is caused by surface damage during ball milling. (C) 2013 Elsevier B.V. All rights reserved.

  19. Microstructural evolution of nanostructured Ti{sub 0.7}Ni{sub 0.3}N prepared by reactive ball-milling

    SciTech Connect

    Bhaskar, Ujjwal Kumar; Pradhan, S.K.

    2013-09-01

    Graphical abstract: - Highlights: • α-Ti to β-Ti phase conversion is observed during 1 h of milling. • Ti{sub 0.7}Ni{sub 0.3}N (fcc) phase is noticed to form after 1 h of milling. • Formation time of Ti(Ni,N) phase is same as TiN phase. • Both X-ray and HRTEM microstructure characterization revealed similar results. - Abstract: Nanocrystalline stoichiometric Ti{sub 0.7}Ni{sub 0.3}N powder has been synthesized by ball-milling the α-Ti (hcp) and Ni (fcc) powders under N{sub 2} gas at room temperature. The α-Ti phase partially transforms to the transient (-Ti phase after 1 h of milling. After 5.5 h of milling, very broad reflections of Ti{sub 0.7}Ni{sub 0.3}N phase is noticed. Complete formation of Ti{sub 0.7}Ni{sub 0.3}N phase is observed after 9 h of milling. Microstructure in terms of lattice imperfections of unmilled and all ball-milled powder mixtures are primarily characterized by analyzing the X-ray powder diffraction patterns employing the Rietveld structure refinement procedure. It clearly reveals the presence of Ti{sub 0.7}Ni{sub 0.3}N phase and inclusion of nitrogen atoms into the α-Ti–Ni matrix on the way to formation of nitride phase. Microstructure of the ball milled nitride powders is also characterized by HRTEM. Particle size of Ti{sub 0.7}Ni{sub 0.3}N phase obtained from XRD method of characterization is ∼5 nm which is very close to that obtained from HRTEM.

  20. Magnetic properties of ball-milled SrFe12O19 particles consolidated by Spark-Plasma Sintering.

    PubMed

    Stingaciu, Marian; Topole, Martin; McGuiness, Paul; Christensen, Mogens

    2015-01-01

    The room-temperature magnetic properties of ball-milled strontium hexaferrite particles consolidated by spark-plasma sintering are strongly influenced by the milling time. Scanning electron microscopy revealed the ball-milled SrFe12O19 particles to have sizes varying over several hundred nanometers. X-Ray powder-diffraction studies performed on the ball-milled particles before sintering clearly demonstrate the occurrence of a pronounced amorphization process. During sintering at 950 °C, re-crystallization takes place, even for short sintering times of only 2 minutes and transformation of the amorphous phase into a secondary phase is unavoidable. The concentration of this secondary phase increases with increasing ball-milling time. The remanence and maximum magnetization values at 1T are weakly influenced, while the coercivity drops dramatically from 2340 Oe to 1100 Oe for the consolidated sample containing the largest amount of secondary phase. PMID:26369360

  1. Magnetic properties of ball-milled SrFe12O19 particles consolidated by Spark-Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Stingaciu, Marian; Topole, Martin; McGuiness, Paul; Christensen, Mogens

    2015-09-01

    The room-temperature magnetic properties of ball-milled strontium hexaferrite particles consolidated by spark-plasma sintering are strongly influenced by the milling time. Scanning electron microscopy revealed the ball-milled SrFe12O19 particles to have sizes varying over several hundred nanometers. X-Ray powder-diffraction studies performed on the ball-milled particles before sintering clearly demonstrate the occurrence of a pronounced amorphization process. During sintering at 950 oC, re-crystallization takes place, even for short sintering times of only 2 minutes and transformation of the amorphous phase into a secondary phase is unavoidable. The concentration of this secondary phase increases with increasing ball-milling time. The remanence and maximum magnetization values at 1T are weakly influenced, while the coercivity drops dramatically from 2340 Oe to 1100 Oe for the consolidated sample containing the largest amount of secondary phase.

  2. Magnetic properties of ball-milled SrFe12O19 particles consolidated by Spark-Plasma Sintering

    PubMed Central

    Stingaciu, Marian; Topole, Martin; McGuiness, Paul; Christensen, Mogens

    2015-01-01

    The room-temperature magnetic properties of ball-milled strontium hexaferrite particles consolidated by spark-plasma sintering are strongly influenced by the milling time. Scanning electron microscopy revealed the ball-milled SrFe12O19 particles to have sizes varying over several hundred nanometers. X-Ray powder-diffraction studies performed on the ball-milled particles before sintering clearly demonstrate the occurrence of a pronounced amorphization process. During sintering at 950 oC, re-crystallization takes place, even for short sintering times of only 2 minutes and transformation of the amorphous phase into a secondary phase is unavoidable. The concentration of this secondary phase increases with increasing ball-milling time. The remanence and maximum magnetization values at 1T are weakly influenced, while the coercivity drops dramatically from 2340 Oe to 1100 Oe for the consolidated sample containing the largest amount of secondary phase. PMID:26369360

  3. Formation of budesonide/α-lactose glass solutions by ball-milling

    NASA Astrophysics Data System (ADS)

    Dudognon, E.; Willart, J. F.; Caron, V.; Capet, F.; Larsson, T.; Descamps, M.

    2006-04-01

    The possibility to obtain amorphous budesonide stabilised by blending with an excipient characterised by a higher glass transition temperature, namely α-lactose, has been studied. We carried out the mixing of the two compounds at room temperature by ball-milling. The four obtained blends (containing, respectively, 10, 30, 50 and 70% w of budesonide) are X-ray amorphous and exhibit a single glass transition located between the ones of pure milled crystalline compounds. This revealed that the two amorphous phases are miscible whatever the composition and sufficiently mixed to relax as a whole. Ball-milling thus appears as a powerful tool to form amorphous molecular alloys with enhanced stability properties.

  4. High energy ball milling study of Fe{sub 2}MnSn Heusler alloy

    SciTech Connect

    Jain, Vivek Kumar Lakshmi, N.; Jain, Vishal; Sijo, A. K.; Venugopalan, K.

    2015-06-24

    The structural and magnetic properties of as-melted and high energy ball milled alloy samples have been studied by X-ray diffraction, DC magnetization and electronic structure calculations by means of density functional theory. The observed properties are compared to that of the bulk sample. There is a very good enhancement of saturation magnetization and coercivity in the nano-sized samples as compared to bulk which is explained in terms of structural disordering and size effect.

  5. High-energy ball milling of saquinavir increases permeability across the buccal mucosa.

    PubMed

    Rambharose, Sanjeev; Ojewole, Elizabeth; Branham, Michael; Kalhapure, Rahul; Govender, Thirumala

    2014-05-01

    Saquinavir (SQV), a candidate for buccal drug delivery, is limited by poor solubility. This study identified the effects of high-energy ball milling on the buccal permeability of SQV and compared it to the effects of chemical enhancers, i.e. ethylenediaminetetraacetic acid (EDTA), sodium lauryl sulfate (SLS), polyethylene glycol (PEG) and beta cyclodextrin (β-cyclodextrin). SQV was ball milled using a high energy planetary mill (1, 3, 15 and 30 h) and permeation studies across porcine buccal mucosa were performed using franz diffusion cells. Drug was quantified by UV spectrophotometry. Both unmilled and milled SQV samples were able to permeate the buccal mucosa. Milled samples of 15 h displayed the greatest flux of 10.40 ± 1.24 µg/cm(2 )h and an enhancement ratio of 2.61. All enhancers were able to increase the buccal permeability of unmilled SQV, with SLS achieving the greatest flux (6.99 ± 0.7 µg/cm(2)) and an enhancement ratio of 1.75. However, all the milled SQV samples displayed greater permeability than SLS, the best chemical enhancer for unmilled SQV. Enhanced permeability by ball milling was attributed to reduction in particle size, formation of solid dispersions and an increase in solubility of milled samples. Microscopical evaluation revealed no significant loss in mucosal cellular integrity treated with either unmilled or milled SQV. Histological studies suggest that SQV uses both the paracellular and transcellular route of transport across the mucosa, with drug treatment having no permanent affects. High-energy ball milling was superior to the chemical enhancers studied for enhancement of SQV buccal permeation. PMID:24499179

  6. Microstructure and martensitic transformation in Si-coated TiNi powders prepared by ball milling

    SciTech Connect

    Kim, Jae-hyun; Cho, Gyu-bong; Im, Yeon-min; Chun, Byong-sun; Kim, Yeon-wook; Nam, Tae-hyun

    2013-12-15

    Graphical abstract: - Highlights: • Amorphous Si-coated TiNi powders were prepared successfully by ball milling. • Ti{sub 4}Ni{sub 4}Si{sub 7} was formed at the interface between Si and TiNi after annealing. • Si-coated Ti–Ni powders displayed the R phase after annealing. - Abstract: Si was coated on the surface of Ti–49Ni (at%) alloy powders by ball milling in order to improve the electrochemical properties of the Si electrodes of secondary Li ion batteries and then the microstructure and martensitic transformation behavior were investigated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Ti–Ni powders coated with Si were fabricated successfully by ball milling. As-milled powders consisted of highly deformed Ti–Ni powders with the B2 phase and amorphous Si layers. The thickness of the Si layer coated on the surface of the Ti–Ni powders increased from 3–5 μm to 10–15 μm by extending the milling time from 3 h to 48 h. However, severe contamination from the grinding media, ZrO{sub 2} occurred when the ball milling time was as long as 48 h. By heating as-milled powders to various temperatures in the range of 673–873 K, the highly deformed Ti–Ni powders were recovered and Ti{sub 4}Ni{sub 4}Si{sub 7} was formed. Two-stage B2–R–B19′ transformation occurred when as-milled Si-coated Ti–49Ni alloy powders were heated to temperatures below 873 K, above this temperature one-stage B2–B19′ transformation occurred.

  7. Efficient dehalogenation of automobile shredder residue in NaOH/ethylene glycol using a ball mill.

    PubMed

    Kameda, Tomohito; Fukuda, Yuuzou; Park, Kye-Sung; Grause, Guido; Yoshioka, Toshiaki

    2009-01-01

    We investigated the effectiveness of sodium hydroxide/ethylene glycol (NaOH/EG) for dehalogenation of automobile shredder residue (ASR) using a ball mill. Efficient dehalogenation was achieved at atmospheric pressure by combining the use of EG (196 degrees C b.p.) as a replacement solvent for NaOH with ball milling, which improved contact between ASR and OH(-) in solution. Moderate NaOH concentrations and increased ball mill rotation speeds produced high dechlorination that was not significantly affected by the weight ratio of ASR to EG. NaOH/EG dechlorination increased with temperature with an apparent activation energy of 50 kJ mol(-1) confirming that the reaction proceeded under chemical reaction control. The modified shrinking-core model was appropriate to explain the dechlorination process. Low chloro levels in our NaOH/EG-treated ASR suggested that this material could be used for feedstock recycling and the wet process may be applicable for dehalogenation of other important waste streams. PMID:18929394

  8. Microstructure and Physical Properties of Tb2TiO5 Neutron Absorber Synthesized by Ball Milling and Sintering

    NASA Astrophysics Data System (ADS)

    Huang, Jinghua; Ran, Guang; Liu, Tengjiao; Shen, Qiang; Li, Ning

    2016-08-01

    Tb2TiO5 neutron absorber was synthesized by ball milling and sintering. Microstructure character of ball-milled Tb4O7-17.605%TiO2 (mass fraction, %) powders and sintered bulks was analyzed using XRD, SEM and TEM. The microhardness, coefficient of thermal expansion and thermal conductivity of sintered bulks were measured. The experiment results showed that the nanocrystalline solid solution was obtained during ball milling. After 96 h of ball milling, TiO2 was completely solved in Tb4O7 and the crystal size of Tb4O7 was up to 37 nm. The bulk materials prepared by cold isostatic pressing were sintered at 1300 °C. Tb2TiO5 bulks with an orthorhombic structure were obtained. The microhardness of sintered bulks, as well as the thermal conductivity, increased firstly with increasing ball milling time and then decreased. The coefficient of thermal expansion decreased initially and then increased with increasing ball milling time. For the sintered bulk with powder milled for 48 h, the highest values of both microhardness and thermal conductivity were observed, whereas the lowest coefficient of thermal expansion was exhibited. In addition, with increasing testing temperature, the thermal conductivity of sintered bulks initially fell and then rebounded while an opposite trend was found in the coefficient of thermal expansion.

  9. Ball milling: a green mechanochemical approach for synthesis of nitrogen doped carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Xing, Tan; Sunarso, Jaka; Yang, Wenrong; Yin, Yongbai; Glushenkov, Alexey M.; Li, Lu Hua; Howlett, Patrick C.; Chen, Ying

    2013-08-01

    Technological and scientific challenges coupled with environmental considerations have attracted a search for robust, green and energy-efficient synthesis and processing routes for advanced functional nanomaterials. In this article, we demonstrate a high-energy ball milling technique for large-scale synthesis of nitrogen doped carbon nanoparticles, which can be used as an electro-catalyst for oxygen reduction reactions after a structural refinement with controlled thermal annealing. The resulting carbon nanoparticles exhibited competitive catalytic activity (5.2 mA cm-2 kinetic-limiting current density compared with 7.6 mA cm-2 on Pt/C reference) and excellent methanol tolerance compared to a commercial Pt/C catalyst. The proposed synthesis route by ball milling and annealing is an effective process for carbon nanoparticle production and efficient nitrogen doping, providing a large-scale production method for the development of highly efficient and practical electrocatalysts.Technological and scientific challenges coupled with environmental considerations have attracted a search for robust, green and energy-efficient synthesis and processing routes for advanced functional nanomaterials. In this article, we demonstrate a high-energy ball milling technique for large-scale synthesis of nitrogen doped carbon nanoparticles, which can be used as an electro-catalyst for oxygen reduction reactions after a structural refinement with controlled thermal annealing. The resulting carbon nanoparticles exhibited competitive catalytic activity (5.2 mA cm-2 kinetic-limiting current density compared with 7.6 mA cm-2 on Pt/C reference) and excellent methanol tolerance compared to a commercial Pt/C catalyst. The proposed synthesis route by ball milling and annealing is an effective process for carbon nanoparticle production and efficient nitrogen doping, providing a large-scale production method for the development of highly efficient and practical electrocatalysts. Electronic

  10. Effect of adding ball-milled achenes to must on bioactive compounds and antioxidant activities in fruit wine.

    PubMed

    Lee, Pao-Ju; Chen, Shaun

    2016-03-01

    This study reports the utilization of ball-milled achenes in fermentation to increase the levels of ellagic acid and total phenol content, as well as to enhance the antioxidant capacity of strawberry wine. Achenes were micronized using ball-milling process, and then added to strawberry must prior to fermentation. The effects of the addition of ball-milled achenes on the ellagic acid and total phenol content in strawberry wine were determined, and the free radical scavenging and iron chelation activities were also analyzed. Quality attributes and acceptance were studied in comparison with a leading commercial strawberry wine for market application. The particle sizes of achenes were reduced from 1.1 mm to 400 nm after 30 min of ball-milling, and this led to an increase in the amount of extracted ellagic acid from 550.72 to 915.24 μg/g. The addition of ball-milled achenes to must led to a 19.72 % and 52.37 % increase in ellagic acid and total phenol content in strawberry wine, respectively. The increase in bioactive compounds resulted in increases of 54.09 %, 51.49 % and 56.97 % in ABTS and DPPH radical scavenging, and ferrous ion chelating activities, respectively. Although the commercial strawberry wine showed greater aroma intensity, no significant differences in overall quality and acceptance among the conventional process, added ball-milled achenes and the leading commercial strawberry wines were found. This study demonstrates that supplementation of ball-milled achenes in fermentation can be beneficial in increasing the levels of bioactive compounds and antioxidative capacity, indicating a good market potential. PMID:27570280

  11. Size effect on the melting temperature depression of Al12Mg17 complex metallic alloy nanoparticles prepared by planetary ball milling

    NASA Astrophysics Data System (ADS)

    Zolriasatein, Ashkan; Shokuhfar, Ali

    2015-11-01

    This research investigates the synthesis and size-dependent melting point depression of complex metallic alloy (CMA) nanoparticles. Al12Mg17 which belongs to this new category of intermetallic materials was initially produced as pre-alloyed ingot, then homogenized to achieve single phase compound and crushed into small size powder and finally, mechanically milled in a planetary ball mill to synthesize nanoparticles. Phase and microstructural characterizations of the as-crushed and milled powders were performed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Effects of the mechanical milling on thermal behavior of the Al12Mg17 nanoparticles in comparison with as-cast Al12Mg17 ingot has been investigated by differential scanning calorimetry (DSC) measurement. It was found that an average particle size of 24 nm with crystallite size of 16 nm was achieved after 20 h of ball milling process. The size- dependent melting point depression of the Al12Mg17 nanoparticles has been experimentally observed and also comparison of the obtained results with theoretical models was carried out.

  12. Synthesis of Fe/SiO{sub 2} and iron oxides/SiO{sub 2} nanocomposites by long-term ball milling

    SciTech Connect

    Pozo López, G.; Condó, A.M.; Urreta, S.E.; Silvetti, S.P.

    2014-01-01

    Graphical abstract: - Highlights: • Iron–iron oxides/silica composites are synthesized by long term dry ball-milling. • Bcc iron and α-quartz powders are used as precursors. • Surface effects enhance coercivity in iron/silica nanocomposites. • In spite of their small size, about 10 nm, iron particles are ferromagnetic. • Ferro and superparamagnetic particles are found in maghemite/silica composites. - Abstract: Iron oxide/SiO{sub 2} nanocomposites are synthesized by dry ball-milling a mixture of bcc Fe and α-quartz powders for prolonged times. A sequence of nanocomposites is obtained, with small magnetic particles dispersed in a non magnetic, amorphous matrix. The powders are characterized by X-ray diffraction and transmission electron microscopy. The magnetic hysteresis properties are investigated in the range 50–300 K. After 120 h milling, deformed, non-spherical, α-Fe nanocrystallites of about 10 nm in size and very few small (<10 nm) maghemite particles are found. At room temperature, iron particles are ferromagnetic and a large effective magnetic anisotropy is estimated, which is mainly attributed to surface effects. Between 160 and 200 h milling, maghemite nanoparticles are observed while after 220 h grinding, hematite phase appears; after 340 h milling, the sample consists of ferromagnetic hematite particles with a broad size distribution (5–50 nm) embedded in an amorphous matrix.

  13. Following mechanical activation of salbutamol sulphate during ball-milling with isothermal calorimetry.

    PubMed

    Gaisford, Simon; Dennison, Mansa; Tawfik, Mahmoud; Jones, Matthew D

    2010-06-30

    Formulation of actives for pulmonary delivery with dry powder inhaler devices frequently requires a particle size reduction step. The high-energy forces imparted to a material during milling, as well as reducing particle size, can cause a significant change in physicochemical properties, in particular mechanical activation of the surface (manifested as generation of amorphous regions) which can affect formulated product performance. It is not clear whether particle size reduction occurs prior to, or concomitantly with, generation of amorphous content. In this study the formation of amorphous content with time in crystalline salbutamol sulphate was quantified with isothermal gas perfusion calorimetry as the sample was ball-milled. The data showed that the most particle size reduction occurred initially (d(0.5) dropping from 12.83+/-0.4 to 4.2+/-0.4 within 5 min). During this time period, no detectable amorphous content was observed. Between 5 and 15 min milling time the particle size distribution remained relatively constant but the amorphous content increased non-linearly with time. After 20 min milling time the particle size increased slightly. The data suggest that particle size reduction occurs initially upon application of a force to the crystal. Once maximum particle size reduction has occurred the crystal absorbs the force being applied and the crystal lattice becomes disordered. After extended milling the conditions in the ball mill (heat and/or humidity) may cause crystallisation of some of the amorphous material resulting in particle-particle fusion. It would appear that the ball-milling process could be optimised to achieve the desired particle size distribution but without any loss of crystalline structure. PMID:20385222

  14. A study of the mechanism of microwave-assisted ball milling preparing ZnFe2O4

    NASA Astrophysics Data System (ADS)

    Zhang, Yingzhe; Wu, Yujiao; Qin, Qingdong; Wang, Fuchun; Chen, Ding

    2016-07-01

    In this paper, well dispersed ZnFe2O4 nano-particles with high magnetization saturation of 82.23 emu/g were first synthesized by microwave assisted ball milling and then the influences of pre-treatments and microwave powers to the progress were studied. It was found that under the both function of crack effect induced by ball milling and rotary motion induced by microwave the synthesized ferrtie nano-particles were well dispersed that is much different from the powders synthesized by normal high energy ball milling. The pre-treatment of ball milling can only enhance the reaction rate in the first several hours but the pre-irradiation of microwave can enhance the hole reaction rate. Further more, it was also been found that with increasing the microwave power, the more raw materials will converted into zinc ferrite in the first 5 h. 5 h latter the microwave power of 720 W is high enough for the coupling effect of microwave and ball milling with stirrer rotation speed of 256 rpm.

  15. Efficient production of ZnO nanowires by a ball milling and annealing method

    NASA Astrophysics Data System (ADS)

    Glushenkov, A. M.; Zhang, H. Z.; Zou, J.; Lu, G. Q.; Chen, Y.

    2007-05-01

    ZnO powder was mechanically milled in a ball mill. This procedure was found to greatly increase its evaporation ability. The anomalous evaporation behaviour was caused by the disordered structure of the milled material and was not related to the increase in its surface area after milling. ZnO nanowires were synthesized by evaporation of this milled precursor. Nanowires with smooth and rough surfaces were present in the sample; the latter morphology was dominant. A green emission band centred at 510 nm was dominant in the cathodoluminescence spectrum of the nanowires.

  16. Ball Milling Assisted Solvent and Catalyst Free Synthesis of Benzimidazoles and Their Derivatives.

    PubMed

    El-Sayed, Taghreed H; Aboelnaga, Asmaa; Hagar, Mohamed

    2016-01-01

    Benzoic acid and o-phenylenediamine efficiently reacted under the green solvent-free Ball Milling method. Several reaction parameters were investigated such as rotation frequency; milling balls weight and milling time. The optimum reaction condition was milling with 56.6 g weight of balls at 20 Hz frequency for one hour milling time. The study was extended for synthesis of a series of benzimidazol-2-one or benzimidazol-2-thione using different aldehydes; carboxylic acids; urea; thiourea or ammonium thiocyanate with o-phenylenediamine. Moreover; the alkylation of benzimidazolone or benzimidazolthione using ethyl chloroacetate was also studied. PMID:27563861

  17. Energy efficiency of cement finish grinding in a dry batch ball mill

    SciTech Connect

    Touil, D.; Belaadi, S.; Frances, C. . E-mail: Christine.Frances@ensiacet.fr

    2006-03-15

    Dry grinding experiments on cement clinker were carried out using a laboratory batch ball mill equipped with torque measurement. The specific energy was found to be dependent on operating parameters and clinker environment. Additional compounds such as gypsum and pozzolanic tuff improve energy efficiency. The optimal parameters allowing maximising the energy efficiency factor were determined. Energy efficiency factors were obtained both on the crude material (size minus 2.8 mm) and on a sieved fraction (1-0.71 mm). They demonstrate that a low initial rate of breakage implies higher energy efficiency. On the contrary, conditions ensuring an initial maximal rate of breakage lead to an increase of the energy consumption.

  18. Parametric evaluation of ball milling of SiC in water

    NASA Technical Reports Server (NTRS)

    Kiser, J. D.; Herbell, T. P.; Freedman, M. R.

    1985-01-01

    A statistically designed experiment was conducted to determine optimum conditions for ball milling alpha-SiC in water. The influence of pH adjustment, volume percent solids loading, and mill rotational speed on grinding effectiveness was examined. An equation defining the effect of those milling variables on specific surface area was obtained. The volume percent solids loading of the slurry had the greatest influence on the grinding effectiveness in terms of increase in specific surface area. As grinding effectiveness improved, mill and media wear also increased. Contamination was minimized by use of sintered alpha-SiC milling hardware.

  19. Strong textured SmCo5 nanoflakes with ultrahigh coercivity prepared by multistep (three steps) surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhao, Xin; Xiong, Jie-Fu; Zhang, Ming; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-08-01

    The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity. In addition, the mechanism of coercivity are also studied by the temperature dependence of demagnetization curves for aligned SmCo5 nanoflakes/resin composite, the result indicates that the magnetization reversal could be controlled by co-existed mechanisms of pinning and nucleation.

  20. Strong textured SmCo5 nanoflakes with ultrahigh coercivity prepared by multistep (three steps) surfactant-assisted ball milling

    PubMed Central

    Zuo, Wen-Liang; Zhao, Xin; Xiong, Jie-Fu; Zhang, Ming; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-01-01

    The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity. In addition, the mechanism of coercivity are also studied by the temperature dependence of demagnetization curves for aligned SmCo5 nanoflakes/resin composite, the result indicates that the magnetization reversal could be controlled by co-existed mechanisms of pinning and nucleation. PMID:26272186

  1. Melting process of nanometer-sized in particles embedded in an Al matrix synthesized by ball milling

    SciTech Connect

    Sheng, H.W.; Xu, J.; Yu, L.G.; Sun, X.K.; Hu, Z.Q.; Lu, K.

    1996-11-01

    Dispersions of nanometer-sized In particles embedded in an Al matrix (10 wt.{percent} In) have been synthesized by ball milling of a mixture of Al and In powders. The as-milled product was characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HREM), respectively. It was found that In and Al are pure components immiscible with each other, with nanometer-sized In particles dispersively embedded in the Al matrix. The melting behavior of In particles was investigated by means of differential scanning calorimeter (DSC). The calorimetric measurements indicate that both the melting point and the melting enthalpy of the In nanoparticles decrease with increasing milling time, or refinement of the In particles. Compared to its bulk melting temperature, a melting point depression of 13.4 K was observed when the mean grain size of In is 15 nm, and the melting point depression of In nanoparticles is proportional to the reciprocal of the mean grain size. The melting enthalpy depression was interpreted according to the two-state concept for the nanoparticles. Melting of the interface was deduced to be an exothermal process due to its large excess energy/volume. {copyright} {ital 1996 Materials Research Society.}

  2. Removal of fluoride from drinking water using modified ultrafine tea powder processed using a ball-mill

    NASA Astrophysics Data System (ADS)

    Cai, Huimei; Xu, Lingyun; Chen, Guijie; Peng, Chuanyi; Ke, Fei; Liu, Zhengquan; Li, Daxiang; Zhang, Zhengzhu; Wan, Xiaochun

    2016-07-01

    A low-cost and highly efficient biosorbent was prepared by loading zirconium(IV) onto ball-milled, ultrafine tea powder (UTP-Zr) for removal of fluoride from drinking water. To evaluate the fluoride adsorption capacity of UTP-Zr over a wide range of conditions, the biosorbent dosage, contact time, initial pH, initial fluoride concentration and presence of other ions were varied. UTP-Zr performed well over the considerably wide pH range of 3-10. The residual concentration of Zr in the treated water was below the limit of detection (0.01 mg/L). Fluoride adsorption by the UTP-Zr biosorbent followed the Langmuir model, with a maximum adsorption capacity of 12.43 mgF/g at room temperature. The fluoride adsorption kinetics fit the pseudo-second-order kinetic model. The synthesized biosorbent was characterized by BET, SEM, EDS, XRD and XPS to reveal how UTP-Zr interacts with fluoride. Results from this study demonstrated that UTP-based biosorbents will be useful and safe for the removal of fluoride from drinking water.

  3. Effect of ball milling and dynamic compaction on magnetic properties of Al2O3/Co(P) composite particles

    NASA Astrophysics Data System (ADS)

    Denisova, E. A.; Kuzovnikova, L. A.; Iskhakov, R. S.; Bukaemskiy, A. A.; Eremin, E. V.; Nemtsev, I. V.

    2014-05-01

    The evolution of the magnetic properties of composite Al2O3/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al2O3 granules were coated with a Co95P5 shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al2O3 powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics—saturation magnetization and coercive field—remained unchanged.

  4. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    SciTech Connect

    Hussain, Zuhailawati; Nur Hawadah, M. S.

    2012-09-06

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900 Degree-Sign C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W{sub 2}C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  5. The crystallization of the nanometersized amorphous ceramic powders by ball milling

    SciTech Connect

    Fan, G.J.; Song, X.P.; Li, Y.L.

    1995-12-31

    The nanometersized amorphous Si{sub 3}N{sub 4} and Si-N-C powders are subjected by high-energy ball milling in order to induce a crystallization process. It was found that after initial 4 seconds of milling a-Si{sub 3}N{sub 4} may rapidly crystallize into a mixture of {alpha}-Si{sub 3}N{sub 4} and {beta}-Si{sub 3}N{sub 4} whereas amorphous Si-N-C powders remain in the amorphous state. These results cannot be interpreted with the local effective temperature rise at the collision sites and the increase of the impurity levels which drive the crystallization. The observed structural changes occurring in a-Si{sub 3}N{sub 4} can be attributed to the mechanical deformation which alters the bonding nature of a-Si{sub 3}N{sub 4}. It was concluded that ball milling is an effective tool to induce the crystallization of some amorphous metallic systems.

  6. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Hussain, Zuhailawati; Nur Hawadah, M. S.

    2012-09-01

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900°C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W2C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  7. Dissipation mechanisms in polycrystalline YBCO prepared by sintering of ball-milled precursor powder

    NASA Astrophysics Data System (ADS)

    Hannachi, E.; Ben Salem, M. K.; Slimani, Y.; Hamrita, A.; Zouaoui, M.; Ben Azzouz, F.; Ben Salem, M.

    2013-12-01

    Magnetoresistivity (ρ(T,H)) measurements of polycrystalline YBa2Cu3Oy (Y-123) and YBa2Cu3Oy embedded with nanoparticles of Y-deficient Y-123, generated by the planetary ball milling, have been compared and analyzed by the Ambegaokar and Halperin phase slip model (AH) and thermally activated flux creep (TAFC). Phase analysis by X-ray diffraction (XRD), granular structure examination by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS), were carried out. SEM analyses show that nanoparticles of Y-deficient Y-123, generated by ball milling, are embedded in the superconducting matrix. The broadening of the resistive transition under magnetic field is found to possess two distinct regions, which suggests that dissipation phenomenon in milled and unmilled samples is caused by two mechanisms: the order parameter fluctuations and the vortex-dynamics separated by a crossover temperature T. The critical current Jc(0) at zero temperature in the grain boundaries decreases as a power law, H, which is an indication of the sensitivity of a single junction between the superconducting grains to the applied magnetic field. Jc(0) of the milled material is higher than the one of the unmilled and the activation energies of vortex flux motion U(H) behavior in the applied magnetic field is enhanced by the presence of the nanoparticles embedded in the matrix.

  8. High-energy ball milling technique for ZnO nanoparticles as antibacterial material

    PubMed Central

    Salah, Numan; Habib, Sami S; Khan, Zishan H; Memic, Adnan; Azam, Ameer; Alarfaj, Esam; Zahed, Nabeel; Al-Hamedi, Salim

    2011-01-01

    Nanoparticles of zinc oxide (ZnO) are increasingly recognized for their utility in biological applications. In this study, the high-energy ball milling (HEBM) technique was used to produce nanoparticles of ZnO from its microcrystalline powder. Four samples were ball milled for 2, 10, 20, and 50 hours, respectively. The structural and optical modifications induced in the ‘as synthesized’ nanomaterials were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and photoluminescence emission spectra (PL). SEM and TEM results show a gradual decrease in particle size from around 600 to ∼30 nm, with increased milling time. The initial microstructures had random shapes, while the final shape became quite spherical. XRD analysis showed ZnO in a hexagonal structure, broadening in the diffracted peaks and going from larger to smaller particles along with a relaxation in the lattice constant c. The value of c was found to increase from 5.204 to 5.217 Å with a decrease in particle size (600 to ∼30 nm). PL result showed a new band at around 365 nm, whose intensity is found to increase as the particles size decreases. These remarkable structural and optical modifications induced in ZnO nanoparticles might prove useful for various applications. The increase in c value is an important factor for increasing the antibacterial effects of ZnO, suggesting that the HEBM technique is quite suitable for producing these nanoparticles for this purpose. PMID:21720499

  9. Stabilizing conditions of metal mercury in mercury sulfurization using a planetary ball mill.

    PubMed

    Fukuda, Naomichi; Takaoka, Masaki; Oshita, Kazuyuki; Mizuno, Tadao

    2014-07-15

    This study used a non-heating process to stabilize mercury by mercury sulfurization. Elemental mercury and sulfur were mixed using planetary ball milling under various experimental conditions and the optimal conditions were determined. The labile intermediate, mercury sulfide, was observed in the early stages of milling, and the intermediates were then pulverized into mercury sulfide powder. These phenomena were significantly influenced by the diameter of the planetary ball. A larger diameter enhanced mercury stabilization. For a ball with a 19.04-mm diameter, the toxicity characteristic leaching procedure (TCLP) and the Japanese leaching test (JLT) values were 0.263μg/L and 0.0586μg/L, respectively, suggesting that mercury leachability was strictly controlled. When the molar ratio of sulfur to mercury was 1.05, the mercury concentration in the headspace was <1μg/Nm(3) at 20°C, which was equivalent to the level in pure reagent. The stability of the planetary ball milling product at optimum conditions was either comparable or superior to that in other stabilization techniques. The running cost of this technology was estimated to be 15,360Yen (154USD)/ton-Hg. This stabilization technology is cost-effective and environmentally sound for the long-term and safe management of mercury. PMID:24929784

  10. Ball mill assisted rapid mechanochemical extraction method for natural products from plants.

    PubMed

    Wang, Man; Bi, Wentao; Huang, Xiaohua; Chen, David Da Yong

    2016-06-01

    A ball mill assisted mechanochemical extraction method was developed to extract compounds of natural product (NP) from plant using ionic liquid (IL). A small volume ball mill, also known as PastPrep(®) Homogenizer, which is often used for high-speed lysis of biological samples and for other applications, was used to dramatically increase the speed, completeness and reproducibility of the extraction process at room temperature to preserve the chemical integrity of the extracted compounds. In this study, tanshinones were selected as target compounds to evaluate the performance of this extraction method. Factors affecting the extraction efficiency, such as the duration, IL concentration and solid/liquid ratio were systematically optimized using the response surface methodology. Under the optimized conditions, the described method was more efficient and much faster than the conventional extraction methods such as methanol based ultrasound assisted extraction (UAE) and heat reflux extraction (HRE) that consumes a lot more organic solvent. In addition, the natural products of interest were enriched by anion metathesis of ionic liquids, combining extraction and preconcentration in the same process. The extractant was analyzed by HPLC and LC-MS. The reproducibility (RSD, n=5), correlation coefficient (r(2)) of the calibration curve, and the limit of detection, were determined to be in the range of 4.7-5.2%, 0.9992-0.9995, and 20-51ng/mL, respectively. PMID:27157426

  11. Effect of ball milling energy on rheological and thermal properties of amaranth flour.

    PubMed

    Roa, Diego F; Baeza, Rosa I; Tolaba, Marcela P

    2015-12-01

    Pearled amaranth grains obtained by abrasive milling were processed by planetary ball milling to produce amaranth flours. The influence of milling energy on rheological and thermal behavior of amaranth flour dispersions and stability during 24 h storage at 4 °C were investigated based on a factorial design. The rheological behavior of flour dispersions (4 % and 8 % w/v) was determined using a rotational viscometer, while gelatinization degree was determined by differential scanning calorimetry as a measure of structural changes.The power law model was found to be suitable in expressing the relationship between shear stress and shear rate. Flour dispersions showed a pseudoplastic behavior. However this character decreased with the storage being dependent on flour concentration and milling energy. A decrease of the consistency index and an increase of the flow behavior index were observed as a result of the increasing milling energy. Gelatinization enthalpy decrease showed the loss of crystalline structure due to ball milling. Amaranth flour dispersions presented increasing stability during storage. It was observed, that the stability changed with the concentration of amaranth flours.Thus, more stable dispersions were obtained as the flour concentration increased. The highly milled sample was the most stable sample during the storage. PMID:26604420

  12. Structural and magnetic properties of the low temperature phase MnBi with ball milling

    NASA Astrophysics Data System (ADS)

    Kavita, S.; Ramakrishna, V. V.; Srinivasan, A.; Gopalan, R.

    2016-05-01

    MnBi has been prepared by arc-melting method and subjected to low energy ball milling after homogenization heat treatment. X-ray diffraction data shows that the weight percentage of the low temperature MnBi (LTP MnBi) phase increases with milling. Microstructural and x-ray peak profile analysis show that milling leads to a reduction in average crystallite size and an increase in microstrain respectively. Magnetic hysteresis loops recorded for an applied field of ±20 kOe show that the alloy milled for 5 h exhibits a coercivity of 11.3 kOe. Although ball milling results in the growth of the LTP MnBi phase, the saturation magnetization (M s) decreases from 47 emu g‑1 (arc melted and homogenized) to 15 emu g‑1 upon milling for 5 h. It is also found that the Curie temperature (T c) of the system decreases with milling. The decrease in magnetization is discussed in terms of variation of Mn–Mn distance and the strain induced during milling. On the other hand, it has been found that the coercivity increases with temperature and reaches a value of 17.5 kOe at 500 K for the 5 h milled sample.

  13. Investigation of phase composition and nanoscale microstructure of high-energy ball-milled MgCu sample.

    PubMed

    Ma, Zongqing; Liu, Yongchang; Yu, Liming; Cai, Qi

    2012-01-01

    The ball milling technique has been successfully applied to the synthesis of various materials such as equilibrium intermetallic phases, amorphous compounds, nanocrystalline materials, or metastable crystalline phases. However, how the phase composition and nanoscale microstructure evolute during ball milling in various materials is still controversial due to the complex mechanism of ball milling, especially in the field of solid-state amorphization caused by ball milling. In the present work, the phase evolution during the high-energy ball milling process of the Mg and Cu (atomic ratio is 1:1) mixed powder was investigated. It was found that Mg firstly reacts with Cu, forming the Mg2Cu alloy in the primary stage of ball milling. As the milling time increases, the diffracted peaks of Mg2Cu and Cu gradually disappear, and only a broad halo peak can be observed in the X-ray diffraction pattern of the final 18-h milled sample. As for this halo peak, lots of previous studies suggested that it originated from the amorphous phase formed during the ball milling. Here, a different opinion that this halo peak results from the very small size of crystals is proposed: As the ball milling time increases, the sizes of Mg2Cu and Cu crystals become smaller and smaller, so the diffracted peaks of Mg2Cu and Cu become broader and broader and result in their overlap between 39° and 45°, at last forming the amorphous-like halo peak. In order to determine the origin of this halo peak, microstructure observation and annealing experiment on the milled sample were carried out. In the transmission electron microscopy dark-field image of the milled sample, lots of very small nanocrystals (below 20 nm) identified as Mg2Cu and Cu were found. Moreover, in the differential scanning calorimetry curve of the milled sample during the annealing process, no obvious exothermic peak corresponding to the crystallization of amorphous phase is observed. All the above results confirm that the broad

  14. Effect of ball-milling surfactants on the interface chemistry in hot-compacted SmCo5 magnets

    SciTech Connect

    Li, WF; Sepehri-Amin, H; Zheng, LY; Cui, BZ; Gabay, AM; Hono, K; Huang, WJ; Ni, C; Hadjipanayis, GC

    2012-11-01

    Anisotropic SmCo5 nanoflakes prepared by high-energy ball-milling with surfactants have great potential in applications for high-performance nanocomposite magnets. For such "nanocomposite" applications, the surface structure and chemistry of nanoflakes are crucial for achieving high coercivity. In this study, hot-pressed samples from anisotropic SmCo5 nanoflakes, ball-milled with different surfactants, oleic acid (OA) and oleylamine (OY), were investigated. Interface layers between the SmCo5 nanoflakes were found to consist of samarium oxides and a soft magnetic Co phase. These surface layers contribute to the degradation of hard magnetic performance, which is confirmed by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy analysis of the cross-section of a single flake ball-milled with OA. Samples milled with OY show a much thinner interface layer in compacted samples, which means that the surface degradation during ball-milling with OY is much less than that with OA. The results show clearly that the choice of proper surfactant and the control of processing parameters are the key factors for improving the surface condition of the nanoflakes and the resulting hard magnetic properties. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Application of planetary ball mill for manufacturing of shielding composite coatings based on polyester powder paints and carbon fillers

    NASA Astrophysics Data System (ADS)

    Panin, S. V.; Yazykov, S. Yu; Suslyaev, V. I.; Dorozhkin, K. V.

    2015-10-01

    Blend polyester powder paint and particulate carbon filler in the form of colloidal graphite and the carbon black product were investigated. Powder paint and carbon materials were treated together in a planetary ball mill. The data of the structural analysis and transmission coefficients of electromagnetic waves of terahertz range through the flat shape samples are presented.

  16. Mössbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    NASA Astrophysics Data System (ADS)

    Pandey, Brajesh; Rao, M. Ananda; Verma, H. C.; Bhargava, S.

    2006-04-01

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Mössbauer spectroscopic studies. In both cases, there is almost no diffusion of Fe in Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Mössbauer spectra showing atomic level mixing. But the two compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  17. Mössbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    NASA Astrophysics Data System (ADS)

    Pandey, Brajesh; Ananda Rao, M.; Verma, H. C.; Bhargava, S.

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Mössbauer spectroscopic studies. In both cases, there is almost no diffusion of Fein Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Mössbauer spectra showing atomic level mixing. But the two. compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  18. Cross-Coupling Biarylation of Nitroaryl Chlorides Through High Speed Ball Milling

    PubMed Central

    Lam, Solita; Puplampu-Dove, Yvonne; Morris, Adrienne; Epps, Ayunna; Mandouma, Ghislain

    2016-01-01

    Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction. Cross-coupling biarylation of several nitroaryl chlorides was achieved in good yields when performed in custom-made copper vials through continuous shaking without additional copper or solvent. Cross-coupling products were obtained almost pure and NMR-ready. These reactions were cleaner than solution phase coupling which require longer reaction time in high boiling solvents, and added catalysts as well as lengthy extraction and purification steps. Gram quantities of cross biaryl compounds have been synthesized with larger copper vials, a proof that this method can be used to reduce industrial waste and for sustainability. PMID:27294205

  19. Hydration of anhydrite of gypsum (CaSO{sub 4}.II) in a ball mill

    SciTech Connect

    Sievert, T.; Wolter, A.; Singh, N.B

    2005-04-01

    The hydration of an anhydrite of gypsum (CaSO{sub 4}.II) in a ball mill was studied as a function of time and temperature. The amount of gypsum formed at different intervals of time was determined by weight loss method and powder X-ray diffraction technique. Specific surface area at different time intervals was determined by LASER granulometric method. The results showed that the maximum rate of formation of gypsum was at a longer time than the time for the development of maximum specific surface area. In the presence of activators, the time for maximum rate of gypsum formation and maximum specific surface area shifted towards lower hydration time. Morphological changes during the course of hydration have been studied by the scanning electron microscopic (SEM) technique. A mechanism of hydration has been proposed.

  20. PrCo5 nanoflakes prepared by surfactant-assisted ball milling at low temperature

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Wei, Hao; Liu, Lidong; Yang, Haitao; Zhang, Jian; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping

    2015-05-01

    Rare-earth permanent magnetic nanoflakes and nanoparticles have drawn great attention due to their potential applications in fabricating permanent magnets with high performance. In this work, the anisotropic PrCo5 nanoflakes were fabricated via surfactant-assisted ball milling at low temperature and room temperature, and the morphology, microstructure, and magnetic properties were investigated systematically. It is found that, compared with the sample milled at room temperature, the PrCo5 nanoflakes prepared at low temperature have a better crystallinity, stronger [001] out-of-plane texture, more regular shape with smaller thickness, and excellent magnetic properties, especially a higher degree of grain alignment and larger remanence ratio (Mr/Ms).

  1. Production of chromium base alloys by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol% ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1540 C. Hot pressed Cr + ThO2 had a DBTT of 500 C as compared with -8 to 24 C for the hot rolled Cr + ThO2 and with 140 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  2. Solid acid-catalyzed depolymerization of barley straw driven by ball milling.

    PubMed

    Schneider, Laura; Haverinen, Jasmiina; Jaakkola, Mari; Lassi, Ulla

    2016-04-01

    This study describes a time and energy saving, solvent-free procedure for the conversion of lignocellulosic barley straw into reducing sugars by mechanocatalytical pretreatment. The catalytic conversion efficiency of several solid acids was tested which revealed oxalic acid dihydrate as a potential catalyst with high conversion rate. Samples were mechanically treated by ball milling and subsequently hydrolyzed at different temperatures. The parameters of the mechanical treatment were optimized in order to obtain sufficient amount of total reducing sugar (TRS) which was determined following the DNS assay. Additionally, capillary electrophoresis (CE) and Fourier transform infrared spectrometry (FT-IR) were carried out. Under optimal conditions TRS 42% was released using oxalic acid dihydrate as a catalyst. This study revealed that the acid strength plays an important role in the depolymerization of barley straw and in addition, showed, that the oxalic acid-catalyzed reaction generates low level of the degradation product 5-hydroxymethylfurfural (HMF). PMID:26859328

  3. Microwave Absorption Properties of Iron Nanoparticles Prepared by Ball-Milling

    NASA Astrophysics Data System (ADS)

    Chu, Xuan T. A.; Ta, Bach N.; Ngo, Le T. H.; Do, Manh H.; Nguyen, Phuc X.; Nam, Dao N. H.

    2016-05-01

    A nanopowder of iron was prepared using a high-energy ball milling method, which is capable of producing nanoparticles at a reasonably larger scale compared to conventional chemical methods. Analyses using x-ray diffraction and magnetic measurements indicate that the iron nanoparticles are a single phase of a body-centered cubic structure and have quite stable magnetic characteristics in the air. The iron nanoparticles were then mixed with paraffin and pressed into flat square plates for free-space microwave transmission and reflection measurements in the 4-8 GHz range. Without an Al backing plate, the Fe nanoparticles seem to only weakly absorb microwave radiation. The reflected signal S 11 drops to zero and a very large negative value of reflection loss ( RL) are observed for Al-backed samples, suggesting the existence of a phase matching resonance near frequency f ˜ 6 GHz.

  4. Effects of crystallinity on dilute acid hydrolysis of cellulose by cellulose ball-milling study

    SciTech Connect

    Zhao, Haibo; Kwak, Ja Hun; Wang, Yong; Franz, James A.; White, John M.; Holladay, Johnathan E.

    2005-12-23

    The dilute acid (0.05 M H2SO4) hydrolysis at 175°C of samples comprising varying fractions of crystalline (α-form) and amorphous cellulose was studied. The amorphous content, based on XRD and NMR, and then the product (glucose) yield, based on HPLC, increased by as much as a factor of three upon ball milling. These results are interpreted in terms of a model involving mechanical disruption of crystallinity by breaking hydrogen bonds in α-cellulose, opening up the structure and making more β-1,4 glycosidic bonds readily accessible to the dilute acid. In parallel with hydrolysis to form liquid phase products, there are reactions of amorphous cellulose that form solid degradation products.

  5. Hydrophobic cellulose films with excellent strength and toughness via ball milling activated acylation of microfibrillated cellulose.

    PubMed

    Deng, Sha; Huang, Rui; Zhou, Mi; Chen, Feng; Fu, Qiang

    2016-12-10

    Cellulose films with excellent mechanical strength are of interest to many researchers, but unfortunately they often lack the ductility and water resistance. This work demonstrates an efficient and easily industrialized method for hydrophobic cellulose films made of modified microfibrillated cellulose (MFC). Prior to film fabrication, the simultaneous exfoliation and acylation of MFC was achieved through the synergetic effect of mechanical and chemical actions generated from ball milling in the presence of hexanoyl chloride. Largely enhanced tensile strength and elongation at break have been achieved (4.98MPa, 4.37% for original MFC films, 140MPa, 21.3% for modified ones). Due to hydrophobicity and compact structure, modified films show excellent water resistance and decreased water vapor permeability. Moreover, optical performance of modified films is also improved compared with the original MFC films. Our work can largely expand the application of this biodegradable resource and ultimately reduce the need for petroleum-based plastics. PMID:27577904

  6. Response to Thermal Exposure of Ball-Milled Cu-Mg/B2O3 Powder Blends

    NASA Astrophysics Data System (ADS)

    Birol, Yucel

    2013-08-01

    The response to thermal exposure of ball-milled Cu-Mg/B2O3 powder blends was investigated in the current study to explore the potential of powder metallurgy route to produce Cu-B alloys. Cu-20Mg alloy powder was mixed with B2O3 and subsequently ball milled for 1 hour. Ball milling alone failed to establish a reaction between Cu-Mg compounds and B2O3. When the ball-milled powder blend was heated, however, B2O3 was reduced by CuMg2 <773 K (500 °C). The Cu2Mg intermetallic phase, which has survived until 773 K (500 °C), was involved in the reduction of the remaining B2O3 at still higher temperatures, while excess Mg reacted with B to produce MgB2 and MgB6 compounds. Cu-Mg alloy with predominantly the CuMg2 phase must be utilized to take advantage of the capacity of the CuMg2 (Cu-43 wt pct Mg) compound to reduce B2O3 at temperatures as low as 773 K (500 °C). Once the Cu-43Mg alloy powder is mixed with B2O3 and the powder blend thus obtained is ball milled and subsequently heated at 500 °C, B2O3 is readily reduced by CuMg2 to yield Cu, B, and MgO. The latter can be easily removed from the powder blend by acid leaching.

  7. Studies of superspin glass state and AC-losses in La0.7Sr0.3MnO3 nanoparticles obtained by high-energy ball-milling

    NASA Astrophysics Data System (ADS)

    Phong, P. T.; Manh, D. H.; Nguyen, L. H.; Tung, D. K.; Phuc, N. X.; Lee, I.-J.

    2014-11-01

    Single-phase perovskite compound La0.7Sr0.3MnO3 was synthesized by a high-energy ball milling method. Nanoparticle nature of this manganite with the average particle diameter of 11 nm was revealed from structure and morphology characterizations. The results of ac magnetic susceptibility measurements show that the system can be described as an ensemble of interacting magnetic nanoparticles, which indicates that the dipole-dipole interactions are strong enough to create superspin glass state in the sample. Furthermore, the specific loss power which is exhausted on the irradiation of an ensemble of particles with a magnetic field has been calculated and measured experimentally.

  8. Synthesis of stoichiometric Ca2Fe2O5 nanoparticles by high-energy ball milling and thermal annealing

    NASA Astrophysics Data System (ADS)

    Amorim, B. F.; Morales, M. A.; Bohn, F.; Carriço, A. S.; de Medeiros, S. N.; Dantas, A. L.

    2016-05-01

    We report the synthesis of Ca2Fe2O5 nanoparticles by high-energy ball milling and thermal annealing from α-Fe2O3 and CaCO3. Magnetization measurements, Mössbauer and X-ray spectra reveal that annealing at high temperatures leads to better quality samples. Our results indicate nanoparticles produced by 10 h high-energy ball milling and thermal annealing for 2 h at 1100 °C achieve improved stoichiometry and the full weak ferromagnetic signal of Ca2Fe2O5. Samples annealed at lower temperatures show departure from stoichiometry, with a higher occupancy of Fe3+ in octahedral sites, and a reduced magnetization. Thermal relaxation for temperatures in the 700-1100 °C range is well represented by a Néel model, assuming a random orientation of the weak ferromagnetic moment of the Ca2Fe2O5 nanoparticles.

  9. ZnO nanoparticles obtained by ball milling technique: Structural, micro-structure, optical and photo-catalytic properties

    NASA Astrophysics Data System (ADS)

    Balamurugan, S.; Joy, Josny; Godwin, M. Anto; Selvamani, S.; Raja, T. S. Gokul

    2016-05-01

    The ZnO nanoparticles were obtained by ball milling of commercial grade ZnO powder at 250 rpm for 20 h and studied their structural, micro-structure, optical and photo-catalytic properties. Due to ball milling significant decrease in lattice parameters and average crystalline size is noticed for the as-milled ZnO nano powder. The HRSEM images of the as-milled powder consist of agglomerated fine spherical nanoparticles in the range of ~10-20 nm. The room temperature PL spectrum of as-milled ZnO nano powder excited under 320 nm reveals two emission bands at ~406 nm (violet emission) and ~639 nm (green emission). Interestingly about 98 % of photo degradation of methylene (MB) by the ZnO catalyst is achieved at 100 minutes of solar light irradiation.

  10. Combined pretreatment using alkaline hydrothermal and ball milling to enhance enzymatic hydrolysis of oil palm mesocarp fiber.

    PubMed

    Zakaria, Mohd Rafein; Hirata, Satoshi; Hassan, Mohd Ali

    2014-10-01

    Hydrothermal pretreatment of oil palm mesocarp fiber was conducted in tube reactor at treatment severity ranges of log Ro = 3.66-4.83 and partial removal of hemicellulose with migration of lignin was obtained. Concerning maximal recovery of glucose and xylose, 1.5% NaOH was impregnated in the system and subsequent ball milling treatment was employed to improve the conversion yield. The effects of combined hydrothermal and ball milling pretreatments were evaluated by chemical composition changes by using FT-IR, WAXD and morphological alterations by SEM. The successful of pretreatments were assessed by the degree of enzymatic digestibility of treated samples. The highest xylose and glucose yields obtained were 63.2% and 97.3% respectively at cellulase loadings of 10 FPU/g-substrate which is the highest conversion from OPMF ever reported. PMID:25058299

  11. Acid-Assisted Ball Milling of Cellulose as an Efficient Pretreatment Process for the Production of Butyl Glycosides.

    PubMed

    Boissou, Florent; Sayoud, Nassim; De Oliveira Vigier, Karine; Barakat, Abdellatif; Marinkovic, Sinisa; Estrine, Boris; Jérôme, François

    2015-10-12

    Ball milling of cellulose in the presence of a catalytic amount of H2SO4 was found to be a promising pre-treatment process to produce butyl glycosides in high yields. Conversely to the case of water, n-butanol has only a slight effect on the recrystallization of ball-milled cellulose. As a result, thorough depolymerization of cellulose prior the glycosylation step is no longer required, which is a pivotal aspect with respect to energy consumption. This process was successfully transposed to wheat straw from which butyl glycosides and xylosides were produced in good yields. Butyl glycosides and xylosides are important chemicals as they can be used as hydrotropes but also as intermediates in the production of valuable amphiphilic alkyl glycosides. PMID:26346950

  12. Characterization and Optimization Multiscale and Multicomponent Nanosystems

    NASA Astrophysics Data System (ADS)

    Nash, Kelly

    2012-10-01

    Materials with new combinations of properties are increasingly needed to meet the requirements of energy, transportation, and medical applications. The use of multi-component systems, with potentially complementary properties, represent a unique path to improve materials properties for a variety of applications. Among the most interesting applications of these materials is in the development of contrast agents in biological imaging and dynamic sensing applications. Although a variety of techniques to characterize these materials exist, noninvasive characterization methods, such as optical-based techniques, are ideal for studying these materials in their native states and for monitoring dynamic changes. The proposition becomes even more attractive when at least one of the components carries an optical signature.The use of optoacoustic (OA) is an emerging technology based on studying optically absorbing nano and microstructures in the sample by recording transit pressure waves generated from laser-induced thermal expansion. More recently OA has been developed as a vibrant technology for medical applications and some growing applications is for material characterization in research and industrial applications. Specifically, OA can assist in the characterization and optimization of composite materials containing nanoparticles when paired with other characterization techniques. The present work illustrates an overview of select hybrid nanomaterials, including their unique optoacoustic signatures utilizing an all optical OA technique. The results of this work show that optical based techniques such as OA, provide a noninvasive, nondestructive means to study multi-material, multi-scale, multi-functional materials are important in the development of novel multi-component nanomaterial schemes and elucidating the structure-function relationship in these materials.

  13. Self-sintering-assisted high intergranular connectivity in ball-milled ex situ MgB2 bulks

    NASA Astrophysics Data System (ADS)

    Mizutani, Shunsuke; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Ogino, Hiraku; Kishio, Kohji

    2014-11-01

    To understand the mechanisms leading to higher intergranular connectivity in polycrystalline ex situ MgB2 prepared using a pressure-less self-sintering technique, the influence of the initial particle size of the MgB2 powder was investigated. MgB2 bulks sintered at 900 °C for 24 h using ball-milled powders exhibited a network structure with both qualitatively and quantitatively improved intergranular couplings. The connectivity calculated using normal-state transport measurements reached a high value of ˜40%, which is comparable to that of MgB2 bulks fabricated via Mg diffusion or high-pressure-assisted processes. Moreover, the sintering time required to achieve a reasonably high connectivity of 25-30% was less than 1 h. Notably, microstructural analyses confirmed the formation of intergranular necks and grain boundaries during the early stage of sintering. These results suggested self-sintering of the ball-milled MgB2 bulks proceeded much more rapidly than those sintered using an MgB2 powder without ball-milling. Increased intergranular contact points and decreased gap length between grains in green compact are assumed to be the origins for the stimulated self-sintering and corresponding increase in the electrical connectivity.

  14. Study on preparation of the core-nanoshell composite absorbers by high-energy ball milling at room temperature.

    PubMed

    Che, Ruxin; Gao, Hong; Yu, Bing; Wang, Shuo; Wang, Chunxia

    2012-02-01

    Electromagnetic (EM) wave pollution has become the chief physical pollution for environment. In recent years, some researches have been focused on the preparation of nano-composite absorbers at low temperatures or even at room temperature. In this letter, preparation of nanocomposite by using high-energy ball milling at room temperature is reported. The core-nanoshell composite absorbers with magnetic fly-ash hollow cenosphere (MFHC) as nuclear and nanocrystalline magnetic material as shell were prepared by high-energy ball milling and vacuum-sintering in this paper. The pre-treatment of MFHC, the sintering process and the mol ratio of starting chemicals had a significant impact for property of composite absorbers. The results of X-ray diffraction analysis (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) analysis indicated that perfect-crystalline nanomagnetic material coating was gotten with a particle size of 12 nm after ball milling. The results show the MFHC is dielectric loss and magnetic loss too; the exchange-coupling interaction happened between ferrite of the MFHC and nanocrystalline magnetic material coating. The exchange-coupling interaction enhances magnetic loss of composite absorbers. They have a perfect EM parameters at low microwave frequency. The core-nanoshell composite absorbers have a higher magnetic loss at low frequencies, and it is consistent with requirements of the microwave absorbing material at the low-frequency absorption. The microwave absorptivity of the core-nanoshell composite absorbers is better than single material. PMID:22630008

  15. Crystallization and microstructure of 8YSZ nanopowders synthesized by ball-mill assisted constant pH route

    NASA Astrophysics Data System (ADS)

    Mohanty, Subrat K.; Nayak, Bibhuti B.

    2013-06-01

    8 mol% Y2O3 stabilized ZrO2 (8YSZ) nanopowders were prepared by two ways of precipitation technique namely conventional precipitation (i.e. stepwise increase of pH) and constant pH precipitation (i.e. precipitation at constant pH). The crystallization, microstructure and density of both the powders were studied with and without ball milling. The ball milled powders prepared in conventional method were found to be sintered upto 92% of the theoretical density, whereas the powders prepared in constant pH precipitation method after ball milling showed 97% of the theoretical density, at 1600°C. The presence of fine and uniformly distributed pores were observed, for the 8YSZ pellets synthesized via conventional precipitation method, whereas a relatively dense microstructure was observed for that synthesized via constant pH precipitation method, from the SEM micrographs. Constant pH route shows better results as compared to conventional route and seems to be effective way of synthesis to prepare 8YSZ for electrolyte in solid oxide fuel cell (SOFC) application.

  16. Structure and microwave characteristics of Co/TiO2 nanocomposites prepared by ball milling.

    PubMed

    Ni, Xia; Ma, Ji; Li, Jiangong; Huang, Juanjuan; Jiao, Dongmao; Lu, Zhibin

    2008-09-01

    Co/TiO2 nanocomposites were fabricated via direct ball milling. The structure and microwave characteristics of the Co/TiO2 nanocomposites were investigated. The results show that the hcp and fcc Co phases coexist in the nanocomposites for a long milling duration. The accumulation of the stacking faults in Co and the increase of the Co/TiO2 interfaces were detected by nuclear magnetic resonance. The measured relative complex permittivity of the ComTiO2 nanocomposite-paraffin wax mixture indicates that a high electrical resistivity and a dielectric loss exist in the Co/TiO2 nanocomposites. The dielectric loss mainly results from the polarisation of the metal/insulator interfaces. The imaginary part of the relative complex permeability of the mixture exhibits a broad resonance peak at 5.1 GHz which originates from the natural resonance in Co. The broadening of the resonance peak can be attributed to the fluctuating magnetocrystalline anisotropy at the stacking faults and interfaces regions. The calculated reflection loss curves show that the minimal reflection loss value of the Co/TiO2 nanocomposite-paraffin wax mixture can reach -32 dB at 4.0 GHz with a 3 mm sample thickness. The improved microwave absorption properties may result from the high electrical resistivity, dielectric loss and natural resonance. PMID:19049042

  17. Room temperature dual ferroic behaviour of ball mill synthesized NdFeO3 orthoferrite

    NASA Astrophysics Data System (ADS)

    Aparnadevi, N.; Saravana Kumar, K.; Manikandan, M.; Paul Joseph, D.; Venkateswaran, C.

    2016-07-01

    Phase pure NdFeO3 has been achieved using high energy ball milling of oxide precursors with subsequent sintering. It is established that structural arrangement of NdFeO3 regulates the multifunctional feature of the material. Rietveld refinement of the room temperature X-ray diffraction pattern shows that the Fe-O-Fe bond angle significantly favors the super exchange interaction, which is predominantly antiferromagnetic in nature. Magnetization measurement illustrates antiferromagnetic behaviour with a weak ferromagnetic component caused by the canted nature of the Fe3+ spins at room temperature. Absorption bands in the visible ambit, apparent from the UV-Vis diffuse reflectance studies, is found due to the crystal ligand field of octahedral oxygen environment of Fe3+ ions. The direct band gap is estimated to be 2.39 eV from the diffuse reflectance spectrum. The lossy natured ferroelectric loop having a maximum polarization of 0.23 μC/cm2 at room temperature is found to be driven by the non-collinear magnetic structure with reverse Dzyaloshinskii-Moriya effect. Magnetic field has influence on the dielectric constant as evident from the impedance spectroscopy, indicating the strong coupling between ferroelectric and the magnetic structure of NdFeO3.

  18. Dioxins reformation and destruction in secondary copper smelting fly ash under ball milling

    NASA Astrophysics Data System (ADS)

    Cagnetta, Giovanni; Hassan, Mohammed Mansour; Huang, Jun; Yu, Gang; Weber, Roland

    2016-03-01

    Secondary copper recovery is attracting increasing interest because of the growth of copper containing waste including e-waste. The pyrometallurgical treatment in smelters is widely utilized, but it is known to produce waste fluxes containing a number of toxic pollutants due to the large amount of copper involved, which catalyses the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (“dioxins”). Dioxins are generated in secondary copper smelters on fly ash as their major source, resulting in highly contaminated residues. In order to assess the toxicity of this waste, an analysis of dioxin-like compounds was carried out. High levels were detected (79,090 ng TEQ kg‑1) in the ash, above the Basel Convention low POPs content (15,000 ng TEQ kg‑1) highlighting the hazardousness of this waste. Experimental tests of high energy ball milling with calcium oxide and silica were executed to assess its effectiveness to detoxify such fly ash. Mechanochemical treatment obtained 76% dioxins reduction in 4 h, but longer milling time induced a partial de novo formation of dioxins catalysed by copper. Nevertheless, after 12 h treatment the dioxin content was substantially decreased (85% reduction) and the copper, thanks to the phenomena of incorporation and amorphization that occur during milling, was almost inactivated.

  19. Dioxins reformation and destruction in secondary copper smelting fly ash under ball milling.

    PubMed

    Cagnetta, Giovanni; Hassan, Mohammed Mansour; Huang, Jun; Yu, Gang; Weber, Roland

    2016-01-01

    Secondary copper recovery is attracting increasing interest because of the growth of copper containing waste including e-waste. The pyrometallurgical treatment in smelters is widely utilized, but it is known to produce waste fluxes containing a number of toxic pollutants due to the large amount of copper involved, which catalyses the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans ("dioxins"). Dioxins are generated in secondary copper smelters on fly ash as their major source, resulting in highly contaminated residues. In order to assess the toxicity of this waste, an analysis of dioxin-like compounds was carried out. High levels were detected (79,090 ng TEQ kg(-1)) in the ash, above the Basel Convention low POPs content (15,000 ng TEQ kg(-1)) highlighting the hazardousness of this waste. Experimental tests of high energy ball milling with calcium oxide and silica were executed to assess its effectiveness to detoxify such fly ash. Mechanochemical treatment obtained 76% dioxins reduction in 4 h, but longer milling time induced a partial de novo formation of dioxins catalysed by copper. Nevertheless, after 12 h treatment the dioxin content was substantially decreased (85% reduction) and the copper, thanks to the phenomena of incorporation and amorphization that occur during milling, was almost inactivated. PMID:26975802

  20. Insertion compounds and composites made by ball milling for advanced sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M.; Tarascon, Jean-Marie

    2016-01-01

    Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P'2-Na1[Fe0.5Mn0.5]O2 and C/`Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology.

  1. Iron Nanoparticles Fabricated by High-Energy Ball Milling for Magnetic Hyperthermia

    NASA Astrophysics Data System (ADS)

    Tung, D. K.; Manh, D. H.; Phong, L. T. H.; Nam, P. H.; Nam, D. N. H.; Anh, N. T. N.; Nong, H. T. T.; Phan, M. H.; Phuc, N. X.

    2016-05-01

    Iron nanoparticles (FeNPs) have been successfully prepared by high-energy ball milling in air for various milling times from 1 h to 32 h. Their structure, particle size, elemental composition, magnetic, and inductive heating properties were investigated by means of x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, energy-dispersive x-ray (EDX) spectroscopy, vibrating-sample magnetometry, and magnetic induction heating, respectively. XRD analysis showed that the average crystallite size decreased to 11 nm after 10 h of milling, then remained almost unchanged for longer milling times. Coexistence of iron (Fe) and iron oxide (FeO) phases was detected after 12 h of milling. EDX analysis also confirmed the occurrence of oxidation, which can be reconciled with the corresponding decrease and increase in saturation magnetization ( M s) with milling time when exposed to oxygen and when annealed under H2 ambient due to oxygen reduction. The time-dependent magnetic and inductive heating responses of the FeNPs were investigated for prospective application in magnetic hyperthermia. The effect of varying the alternating-current (AC) magnetic field strength on the saturation heating temperature and specific loss power of FeNP-containing ferrofluid with concentration of 4 mg/mL was also studied and is discussed.

  2. Analysis of the Magnetocaloric Effect in Powder Samples Obtained by Ball Milling

    NASA Astrophysics Data System (ADS)

    Blázquez, J. S.; Ipus, J. J.; Moreno-Ramírez, L. M.; Borrego, J. M.; Lozano-Pérez, S.; Franco, V.; Conde, C. F.; Conde, A.

    2015-06-01

    Since the discovery of the giant magnetocaloric effect (MCE) close to room temperature in FeRh and particularly in Gd5Si2Ge2 compounds, the study of this phenomenon has experienced an exponential growth. Among the different techniques used to produce magnetocaloric materials, ball milling has been shown as a very versatile one and presents several advantages over other preparation techniques ( e.g., easy scale-up to industrial production). Although a general decrease of the peak value of the magnetic entropy change is observed for milled samples, it can be compensated by the large broadening of the MCE peak, leading to an increase of the refrigeration capacity. In this short review, several aspects inherent to powder samples affecting MCE will be discussed, such as the relevant effect of the demagnetizing field, the possible multiphase character, and the presence of Curie temperature distributions. In mechanically alloyed samples, the two latter factors are typically affected by the degree of integration of the different starting constituents.

  3. Fluid mechanics of slurry flow through the grinding media in ball mills

    SciTech Connect

    Songfack, P.K.; Rajamani, R.K.

    1995-12-31

    The slurry transport within the ball mill greatly influences the mill holdup, residence time, breakage rate, and hence the power draw and the particle size distribution of the mill product. However, residence-time distribution and holdup in industrial mills could not be predicted a priori. Indeed, it is impossible to determine the slurry loading in continuously operating mills by direct measurement, especially in industrial mills. In this paper, the slurry transport problem is solved using the principles of fluid mechanics. First, the motion of the ball charge and its expansion are predicted by a technique called discrete element method. Then the slurry flow through the porous ball charge is tackled with a fluid-flow technique called the marker and cell method. This may be the only numerical technique capable of tracking the slurry free surface as it fluctuates with the motion of the ball charge. The result is a prediction of the slurry profile in both the radial and axial directions. Hence, it leads to the detailed description of slurry mass and ball charge within the mill. The model predictions are verified with pilot-scale experimental work. This novel approach based on the physics of fluid flow is devoid of any empiricism. It is shown that the holdup of industrial mills at a given feed percent solids can be predicted successfully.

  4. Catalytic hydrodechlorination of monochloroacetic acid in wastewater using Ni-Fe bimetal prepared by ball milling.

    PubMed

    Zhu, Hong; Xu, Fuyuan; Zhao, Jianzhuang; Jia, Linfang; Wu, Kunming

    2015-09-01

    Monochloroacetic acid (MCA) is a chemically stable and biologically toxic pollutant. It is often generated during the production of the pesticide dimethoate. Conventional wastewater treatment processes have difficulty degrading it. In this work, the dechlorination effects of Ni-Fe bimetal prepared using ball milling (BM) technology for the high concentrations of MCA in wastewater were examined. The MCA in aqueous solution was found to be degraded efficiently by the Ni-Fe bimetal. However, S-(methoxycarbonyl) methyl O, O-dimethyl phosphorodithioate (SMOPD) in wastewater, a by-product of the dimethoate production process, significantly inhibited the reductive dechlorination activity of Ni-Fe bimetal. Increasing the reaction temperature in the MCA wastewater enhanced the reduction activity of the Ni-Fe bimetal effectively. Oxygen was found to be unfavorable to dechlorination. Sealing the reaction to prevent oxidation was found to render the degradation process more efficient. The process retained over 88% efficiency after 10 treatment cycles with 50 g/L of Ni-Fe bimetal under field conditions. PMID:25976331

  5. Dioxins reformation and destruction in secondary copper smelting fly ash under ball milling

    PubMed Central

    Cagnetta, Giovanni; Hassan, Mohammed Mansour; Huang, Jun; Yu, Gang; Weber, Roland

    2016-01-01

    Secondary copper recovery is attracting increasing interest because of the growth of copper containing waste including e-waste. The pyrometallurgical treatment in smelters is widely utilized, but it is known to produce waste fluxes containing a number of toxic pollutants due to the large amount of copper involved, which catalyses the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (“dioxins”). Dioxins are generated in secondary copper smelters on fly ash as their major source, resulting in highly contaminated residues. In order to assess the toxicity of this waste, an analysis of dioxin-like compounds was carried out. High levels were detected (79,090 ng TEQ kg−1) in the ash, above the Basel Convention low POPs content (15,000 ng TEQ kg−1) highlighting the hazardousness of this waste. Experimental tests of high energy ball milling with calcium oxide and silica were executed to assess its effectiveness to detoxify such fly ash. Mechanochemical treatment obtained 76% dioxins reduction in 4 h, but longer milling time induced a partial de novo formation of dioxins catalysed by copper. Nevertheless, after 12 h treatment the dioxin content was substantially decreased (85% reduction) and the copper, thanks to the phenomena of incorporation and amorphization that occur during milling, was almost inactivated. PMID:26975802

  6. Effects of ball-milling and cryomilling on sulfamerazine polymorphs: a quantitative study.

    PubMed

    Macfhionnghaile, Pól; Hu, Yun; Gniado, Katarzyna; Curran, Sinead; Mcardle, Patrick; Erxleben, Andrea

    2014-06-01

    The effects of ball-milling and cryomilling on sulfamerazine forms I and II (SMZ FI, FII) were investigated using X-ray powder diffraction, infrared and near-infrared (NIR) spectroscopy. Cryomilling resulted in a complete amorphization of both polymorphs. Milling at room temperature gave mixtures of amorphous SMZ (FA) and FII. Calibration models were developed for the quantitative analysis of binary (FI/FII, FI/FA, and FII/FA) and ternary (FI/FII/FA) mixtures using NIR spectroscopy combined with partial least-squares (PLS) regression. The PLS models for binary (0%-100%), ternary (0%-100%), and low-level (0%-10%) binary mixtures had root-mean-square errors of prediction of ≤1.8%, ≤5.1%, and ≤0.80%, respectively. The calibration models were used to obtain a detailed quantitative picture of solid-state transformations during milling and any subsequent recrystallizations. FA prepared by cryomilling FI for less than 60 min recrystallized to mixtures of FI and FII, whereas samples milled for more than 60 min crystallized to pure FII. The effect of comilling SMZ with stoichiometric amounts of additives was investigated. SMZ formed amorphous materials with oxalic, dl-tartaric, and citric acids that were more stable toward recrystallization than FA. Amorphous SMZ/oxalic acid was found to recrystallize to a 2:1 cocrystal during storage. PMID:24756899

  7. Insertion compounds and composites made by ball milling for advanced sodium-ion batteries

    PubMed Central

    Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M.; Tarascon, Jean-Marie

    2016-01-01

    Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P′2-Na1[Fe0.5Mn0.5]O2 and C/‘Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology. PMID:26777573

  8. The effect of high energy ball milling on the crystal structure of GDNi 5

    NASA Astrophysics Data System (ADS)

    Stubičar, M.; Blažina, Ž.; Tonejc, A.; Stubičar, N.; Krumes, D.

    2001-09-01

    X-ray powder diffraction was used to determine the effect of, dry, in air performed high energy ball milling, on the intermetallic compound GdNi 5. It was found that the crystal structure of GdNi 5 is not stable. At the early stage of milling (up to after 10 h of milling) the gadolinium component oxidises causing thus the decomposition of GdNi 5 into monoclinic Gd 2O 3 and metallic nickel. Both, the crystallite (grain) size and the particle size of powder decrease during the early stage of milling. At the later stage of milling (up to 50 h) the nickel phase from the mixture of Gd 2O 3 and nanocrystalline nickel oxidises into nanocrystalline NiO. Therefore, the final product after 150 h of milling of GdNi 5 is a mixture of oxides of the constituent metals, i.e., amorphous Gd 2O 3 and nanocrystalline NiO. Traces of contamination by α-SiO 2 have been observed in the milled powder, being more pronounced as the milling process proceeds. This is ascribed to the wear effect of agate milling assembly.

  9. Effect of ball milling materials and methods on powder processing of Bi2223 superconductors

    NASA Astrophysics Data System (ADS)

    Yavuz, M.; Maeda, H.; Vance, L.; Liu, H. K.; Dou, S. X.

    1998-10-01

    Various milling systems consisting of agate and polypropylene grinding containers, agate and YSZ balls, and dry and wet milling were used in planetary ball-milling and YSZ balls and YSZ container were used in wet and dry attrition milling. The differently milled powders were then evaluated by measurements of particle size, surface area, porosity, size distribution and chemical analysis of the Si, Zr and C contents. The results show that dry milling is much more efficient for particle size reduction in planetary milling than wet milling, whereas wet milling and dry milling gave quite similar results in attrition milling. Meanwhile 0953-2048/11/10/056/img6 contamination was found in powder milled with an agate container with agate balls. Some C contamination from the polypropylene container was detected after milling, but negligible Zr from YSZ balls and C from the grinding carrier (hexane). It was found that after 1 h milling in the planetary mill fracture mechanisms transform from the elastic to the plastic region. Therefore, further milling is not very effective. It was also shown that the Bi2212 phase decomposes into several non-superconducting oxides such as 0953-2048/11/10/056/img7, CuO and a main amorphous phase after extensive dry milling.

  10. Curie temperature and magnetic properties of aluminum doped barium ferrite particles prepared by ball mill method

    NASA Astrophysics Data System (ADS)

    Chen, Daming; Harward, Ian; Baptist, Joshua; Goldman, Sara; Celinski, Zbigniew

    2015-12-01

    Barium ferrite has attracted considerable interest in the fields of permanent magnets and perpendicular magnetic recording due to its strong uniaxial anisotropy and high Curie temperature (Tc). We prepared aluminum doped barium ferrite ceramics (BaAlxFe12-xO19, 0≤x≤6) by the ball mill method. The powder was milled for 96 h, and after forming pellets, annealed for 48 h in air at 1000 °C. The X-ray diffraction (XRD) data show that there are only single hexagonal phases in the samples without any impurity phase. The crystal lattice constants, a and c, were calculated by Cohen's method. Both a and c decrease with increasing x, ranging from 0.588 nm and 2.318 nm to 0.573 nm and 2.294 nm, respectively. A Vibrating Sample Magnetometer (VSM) and Superconducting Quantum Interference Device (SQUID) were used to investigate Tc and magnetic properties of BaFe12-xAlxO19. It is found that Tc decreases with increasing x, from 425 °C to 298 °C. It is also found that the saturated magnetization (4πMs) decreases with increasing x, while the coercivity (Hc) increases with the increase in x. The anisotropy field was also determined from the SQUID measurement.

  11. Experimental study of residence time distributions of ball-mill circuits grinding coal-water mixtures

    SciTech Connect

    Shoji, K.; Takahashi, Y.; Ohtake, A.; Austin, L.G.

    2008-08-15

    Residence time distributions (RTDs) were estimated by water tracing in a number of wet overflow ball mills (diameters 0.38 to 4.65 m) producing dense, coal-water slurries. In open-circuit mills of 0.38 m diameter and various length-diameter (LID) ratios, the mean residence times of solid were also determined from measured mill holdups. Holdup increased with increased mill feed rate, but the mean residence times of coal and water were still equal to each other. The experimental residence time distributions were fitted to the Mori-Jimbo-Yamazaki semi-infinite, axial mixing model, and the dimensionless mixing coefficient was determined for each of 25 tests in single- and two-compartment mills. This coefficient was found to be independent to the feed rate but linearly proportional to the D/L ratio. The mixing coefficient was smaller for two-compartment mills than for single-compartment mills, showing that there was reduced mixing introduced by the diaphragm separating the compartments. Equations are given to scale residence time distributions for changes in mill diameter and length.

  12. The coercivity mechanism of Pr-Fe-B nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhang, Ming; Niu, E.; Shao, Xiao-Ping; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-09-01

    The strong (00l) textured Pr12+xFe82-xB6 (x=0, 1, 2, 3, 4) nanoflakes with high coercivity were prepared by surfactant-assisted ball milling (SABM). The thickness and length of the flakes are mainly in the range of 50-200 nm and 0.5-2 μm, respectively. A coercivity of 4.16 kOe for Pr15Fe79B6 nanoflakes was obtained, which is the maximum coercivity of R2Fe14B (R=Pr, Nd) nanoflakes or nanoparticles reported up to now. The results of XRD and SEM for the aligned Pr15Fe79B6 nanoflakes indicate that a strong (00l) texture is obtained and the easy magnetization direction is parallel to the surface of the flakes. The angular dependence of coercivity for aligned sample indicates that the coercivity mechanism of the as-milled nanoflakes is mainly dominated by domain wall pinning. Meanwhile, the field dependence of coercivity, isothermal (IRM) and dc demagnetizing (DCD) remanence curves also indicate that the coercivity is mainly determined by domain wall pinning, and nucleation also has an important effect. In addition, the mainly interaction of flakes is dipolar coupling. The research of coercivity mechanism for Pr15Fe79B6 nanoflakes is important for guidance the further increase its value, and is useful for the future development of the high performance nanocomposite magnets and soft/hard exchange spring magnets.

  13. Magnetic properties of iron nitride-silica nanocomposite materials prepared by high-energy ball milling.

    PubMed

    Mishra, S R; Viano, A; Roy, S; Ali, N; Losby, J

    2003-06-01

    Powder mixtures of (FexN)y and (SiO2)1-y, with x between 3 and 4 and y equal to 0.2 or 0.6, were ball-milled for 4, 8, 16, 32, and 64 h. X-ray diffraction, thermal analysis, and magnetization measurements allowed an investigation of structural and magnetic properties to be carried out. The samples consist of nanostructured Fe3N and Fe4N particles in a SiO2 matrix. As the milling time increases, the Fe4N phase is eliminated from the particles in favor of Fe3N. Coercive fields as high as 270 and 84 Oe are obtained for (FexN)0.2(SiO2)0.8 at 5 and 300 K, respectively. This higher coercive field, upon cooling, indicates the presence of small superparamagnetic particles. The coercive field also increases with milling time, which is due to the reduced particle size and induced stain. The saturation magnetization decreases with increased milling time as a consequence of an increase in the superparamagnetic fraction and increased strain. Hard and soft magnetic properties are observed for y = 0.2 and y = 0.6 samples, respectively. PMID:14503406

  14. Anisotropic SmCo{sub 5} nanoflakes by surfactant-assisted high energy ball milling

    SciTech Connect

    Cui, B. Z.; Gabay, A. M.; Li, W. F.; Hadjipanayis, G. C.; Marinescu, M.; Liu, J. F.

    2010-05-15

    Crystallographically anisotropic SmCo{sub 5} nanoflakes were fabricated directly by one-step surfactant-assisted high energy ball milling (HEBM) of Sm{sub 17}Co{sub 83} ingot powders for 5 h in heptane and oleic acid (OA) without preprocessing or further annealing. The SmCo{sub 5} nanoflakes have a strong [001] out-of-plane texture. The thickness of nanoflakes is in the range of 8-80 nm while their length is 0.5-8 {mu}m. The surfactant OA plays an important role in the formation of SmCo{sub 5} nanoflakes. HEBM of SmCo{sub 5} ingots in heptane without OA resulted in the formation of magnetically isotropic more or less equiaxed SmCo{sub 5} particles with a size of 2-30 {mu}m. Closely packed 'kebablike' SmCo{sub 5} nanoflakes were formed by HEBM in heptane with 15 wt % OA. HEBM in 150 wt % OA led to well-separated nanoflakes instead of the closely packed kebablike nanostructure. This resulted in the enhanced [001] out-of-plane texture. In-plane transmission electron microscope examination showed that the SmCo{sub 5} nanoflakes were composed of grains with sizes in the range of 4-8 nm. Coercivities of about 18.0 kOe were obtained for the anisotropic SmCo{sub 5} nanoflakes.

  15. Structural and phase transformations during ball milling of titanium in medium of liquid hydrocarbons

    NASA Astrophysics Data System (ADS)

    Dorofeev, G. A.; Lubnin, A. N.; Lad'yanov, V. I.; Mukhgalin, V. V.; Puskkarev, B. E.

    2014-02-01

    It has been shown using X-ray diffraction, scanning electron microscopy, and chemical analysis that, upon ball milling of α-titanium in liquid organic media (toluene and n-heptane), a nanocrystalline fcc phase is formed that is a metastable carbohydride Ti(C,H) deficient in hydrogen and carbon compared to stable carbohydrides. The dimensions of powder particles after milling in toluene and n-heptane differ substantially (are 5-10 and 20-30 μm, respectively. It has been shown that the kinetics of the formation of Ti(C,H) is independent of the milling medium. The atomic ratios H/C in the products of mechanosynthesis agree well with those corresponding to the employed organic media, i.e., H/C = 1.1 for toluene and 2.3 for n-heptane. A solid-liquid mechanism of mechanosynthesis is suggested, which includes repeated processes of particle fracturing with the formation of fresh surfaces, adsorption of liquid hydrocarbons on these surfaces, and subsequent cold welding of the newly formed particles. It is assumed that the formation of the fcc phase in the process of milling is connected with the generation of stacking faults in α-Ti. Upon annealing at 550°C, the fcc phase decomposes with the formation of stable titanium carbide TiC (annealing in a vacuum) or stable titanium carbohydride and a β-Ti(H) solid solution (annealing in argon) with a partial reverse transformation Ti(C,H) → α-Ti in both cases.

  16. Analysis of magnetic and structural properties in La0.6Sr0.4MnO3 ferromagnetic particles under the influence of mechanical ball milling effect

    NASA Astrophysics Data System (ADS)

    Campillo, G.; Gil, A.; Arnache, O.; Beltrán, J. J.; Osorio, J.; Sierra, G.

    2013-11-01

    We have investigated the magnetic, structural and morphological properties of La0.6Sr0.4MnO3 (LSMO-40) manganite particles, synthesized by solid state reaction method. The resulting LSMO-40 powders were milled in air atmosphere during 3, 6 and 12 hours, by using a planetary ball milling. Samples obtained were characterized by X-ray diffraction, scanning electron microscopy - SEM and magnetization measurements as a function of temperature and magnetic field. A Rietveld analysis was carried on each XRD pattern, and was observed a reduction in crystallite average size (Dv) with increased ball milling time, tM. This is associated with a decrease in particle size. A characteristic rhombohedral crystal structure for the LSMO-40 phase was identified (space group R3C), independent of the milling time of the powders. However, from SEM microstructure was observed more homogeneity in the grain distribution by milling process. The results of magnetic characterization, showed that samples with higher tM (smaller grain size), presented the lowest value of the saturation magnetization, which is attributed to surface effects that induce magnetically disordered states with decreasing particle sizes. This magnetic anisotropy surface is evidenced also on the changes of coercive fields, HC, measured at low temperatures, which increased with increasing tM.

  17. Study of morphology and magnetic properties of the HoNi{sub 3} crystalline and ball-milled compound

    SciTech Connect

    Bajorek, Anna; Skornia, Paweł; Prusik, Krystian; Wojtyniak, Marcin; Chełkowska, Grażyna

    2015-03-15

    The morphology and magnetic properties of the HoNi{sub 3} crystalline and ball-milled intermetallic compounds are presented. The polycrystalline HoNi{sub 3} bulk compound crystallizes in the rhombohedral PuNi{sub 3} — type of crystal structure and indicates ferrimagnetic arrangement with the Curie temperature of T{sub C} = 57 ± 2 K, the helimagnetic temperature T{sub h} = 23 ± 2 K with the total saturation magnetic moment of 6.84 μ{sub B}/f.u. at 2 K. The use of the ball-milling method leads to the formation of HoNi{sub 3} nanoflakes with typical thickness of less than 100 nm prone to agglomeration upon milling. The increase of grinding duration leads to the reduction in crystallite size, which was confirmed by various complementary microscopical and diffraction studies. Moreover, the increase in milling duration results in the emergence of the relatively small coercivity (H{sub C}), remanence (M{sub r}) and a variation of the saturation magnetization (M{sub S}). - Graphical abstract: Display Omitted - Highlights: • The ball-milling method exhibits significant potential for producing RT{sub 3} nanopowders. • The AFM method was used for the first time in analysis of R–T nanoflakes morphology. • HoNi{sub 3} compound forms polycrystalline and textured nanoflakes evolving upon milling. • The decrease in crystallite size via grinding is confirmed by XRD, TEM and AFM. • The magnetic parameters were sensitive to the extension of pulverization b.

  18. Development and evaluation of optimized sucrose ester stabilized oleanolic acid nanosuspensions prepared by wet ball milling with design of experiments.

    PubMed

    Li, Wenji; Ng, Ka-yun; Heng, Paul Wan Sia

    2014-01-01

    The aim of this study was to develop optimized sucrose ester (SE) stabilized oleanolic acid (OA) nanosuspensions (NS) for enhanced delivery via wet ball milling by design of experiments (DOE). In this study, SEOA NS batches were prepared by wet ball milling method. Mean particle sizes and polydispersity indices were determined using a nanosizer. The percent encapsulation efficiency, saturation solubility and in vitro dissolution rate were obtained with analyses using HPLC. Preparation methods were optimized by DOE using the Minitab software. The in vitro bioefficacy was obtained by methyl thiazolyl tetrazolium (MTT) measurements in A549 human non small cell lung cancer cell line. The in vivo pharmacokinetics profile was determined using LC-electrospray ionization (ESI)-MS/MS. The study produced spherical SEOA NS particles (ca. 100 nm in diameter) which were found to be able to increase OA saturation solubility considerably. Optimized SEOA-GBD NS (milled at 600 rpm for 3 h, sucrose monolaurate (SEL) : sucrose monopalmitate (SEP) at 9 : 1, w/w; SE : OA at 1 : 1, w/w) was found to be physically stable over 14 d at 4°C. The NS showed much higher dissolution rate, cytotoxicity and bioavailability when compared with the free drug. Thus, the prepared OA as SE stabilized NS particles by wet ball milling enhanced the saturation solubility, in vitro dissolution rate, bioefficacy and in vivo bioavailability of OA. The use of sugar esters may also be potentially applied to other hydrophobic drugs. PMID:24882406

  19. Bismuth-ceramic nanocomposites through ball milling and liquid crystal synthetic methods

    NASA Astrophysics Data System (ADS)

    Dellinger, Timothy Michael

    Three methods were developed for the synthesis of bismuth-ceramic nanocomposites, which are of interest due to possible use as thermoelectric materials. In the first synthetic method, high energy ball milling of bismuth metal with either MgO or SiO2 was found to produce nanostructured bismuth dispersed on a ceramic material. The morphology of the resulting bismuth depended on its wetting behavior with respect to the ceramic: the metal wet the MgO, but did not wet on the SiO2. Differential Scanning Calorimetry measurements on these composites revealed unusual thermal stability, with nanostructure retained after multiple cycles of heating and cooling through the metal's melting point. The second synthesis methodology was based on the use of lyotropic liquid crystals. These mixtures of water and amphiphilic molecules self-assemble to form periodic structures with nanometer-scale hydrophilic and hydrophobic domains. A novel shear mixing methodology was developed for bringing together reactants which were added to the liquid crystals as dissolved salts. The liquid crystals served to mediate synthesis by acting as nanoreactors to confine chemical reactions within the nanoscale domains of the mesophase, and resulted in the production of nanoparticles. By synthesizing lead sulfide (PbS) and bismuth (Bi) particles as proof-of-concept, it was shown that nanoparticle size could be controlled by controlling the dimensionality of the nanoreactors through control of the liquid crystalline phase. Particle size was shown to decrease upon going from three-dimensionally percolating nanoreactors, to two dimensional sheet-like nanoreactors, to one dimensional rod-like nanoreactors. Additionally, particle size could be controlled by varying the precursor salt concentration. Since the nanoparticles did not agglomerate in the liquid crystal immediately after synthesis, bismuth-ceramic nanocomposites could be prepared by synthesizing Bi nanoparticles and mixing in SiO2 particles which

  20. Micromorphological changes and mechanism associated with wet ball milling of Pinus radiata substrate and consequences for saccharification at low enzyme loading.

    PubMed

    Vaidya, Alankar A; Donaldson, Lloyd A; Newman, Roger H; Suckling, Ian D; Campion, Sylke H; Lloyd, John A; Murton, Karl D

    2016-08-01

    In this work, substrates prepared from thermo-mechanical treatment of Pinus radiata chips were vibratory ball milled for different times. In subsequent enzymatic hydrolysis, percent glucan conversion passed through a maximum value at a milling time of around 120min and then declined. Scanning electron microscopy revealed breakage of fibers to porous fragments in which lamellae and fibrils were exposed during ball milling. Over-milling caused compression of the porous fragments to compact globular particles with a granular texture, decreasing accessibility to enzymes. Carbon-13 NMR spectroscopy showed partial loss of interior cellulose in crystallites, leveling off once fiber breakage was complete. A mathematical model based on observed micromorphological changes supports ball milling mechanism. At a low enzyme loading of 2FPU/g of substrate and milling time of 120min gave a total monomeric sugar yield of 306g/kg of pulp which is higher than conventional pretreatment method such as steam exploded wood. PMID:27131293

  1. Textured Pr{sub 2}Fe{sub 14}B flakes with submicron or nanosize thickness prepared by surfactant-assisted ball milling

    SciTech Connect

    Zuo, Wen-Liang E-mail: shenbg@aphy.iphy.ac.cn; Liu, Rong-Ming; Zheng, Xin-Qi; Wu, Rong-Rong; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen E-mail: shenbg@aphy.iphy.ac.cn

    2014-05-07

    The textured Pr{sub 2}Fe{sub 14}B nanoflakes were produced by surfactant-assisted ball milling (SABM). Single phase tetragonal structure was characterized for the samples before and after SABM by X-ray diffraction (XRD). The thickness and length of the as-milled flakes are mainly in the range of 50–150 nm and 0.5–2 μm, respectively. For the field-aligned Pr{sub 2}Fe{sub 14}B nanoflakes, the out-of-plane texture (the easy magnetization direction (EMD) along the c-axis) is indicated from the increasing (00l) peaks in the XRD patterns. SEM image demonstrates that the EMD is parallel to flaky surface, which is different from the RCo{sub 5} (R = rare earth) system with EMD perpendicular to the surface. We propose a hypothesis that the easy glide planes are related with the area of crystal planes. In addition, a large coercivity H{sub c} = 3.9 kOe is observed in the Pr{sub 2}Fe{sub 14}B flakes with strong texture.

  2. Effect of ball milling and dynamic compaction on magnetic properties of Al{sub 2}O{sub 3}/Co(P) composite particles

    SciTech Connect

    Denisova, E. A.; Kuzovnikova, L. A.; Iskhakov, R. S. Eremin, E. V.; Bukaemskiy, A. A.; Nemtsev, I. V.

    2014-05-07

    The evolution of the magnetic properties of composite Al{sub 2}O{sub 3}/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al{sub 2}O{sub 3} granules were coated with a Co{sub 95}P{sub 5} shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al{sub 2}O{sub 3} powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics—saturation magnetization and coercive field—remained unchanged.

  3. In situ synthesis and cell performance of a Si/C core-shell/ball-milled graphite composite for lithium ion batteries.

    PubMed

    Jung, Dong-Won; Kim, Kwang-Hyun; Lee, Jungkyoo; Kong, Byung-Seon; Oh, Eun-Suok

    2013-12-01

    A high-capacity silicon-carbon core-shell (Si/C) supported by ball-milled graphite (BMG) was synthesized in situ using a hydrosilylation reaction and tested as an anode material for lithium ion batteries (LIBs) in the investigation of the effects of dual buffer layers of carbon shell and BMG. The Si/C/BMG sample effectively absorbed high volumetric expansion/contraction generated during charge/discharge process due to the assistance of dual elastic buffers of carbon shell and BMG. As a result, after 50 charge/discharge cycles, the Si/C/BMG electrodes still had a very high capacity of 1615 mAh/g, whereas raw Si, Si/C, and a mechanical mixture of Si/C and BMG were less than 500 mAh/g. The results of various electrochemical characterization techniques revealed that the dual buffer layers were favorable in decreasing electron and ion transfer resistance. It was also shown from ex situ TEM results that the carbon layers behaved as anti-amorphization layers decreasing the amorphization rate of crystalline Si during the alloying/dealloying of Li with Si. PMID:24266152

  4. Fast environment-friendly ball mill-assisted deep eutectic solvent-based extraction of natural products.

    PubMed

    Wang, Man; Wang, Jiaqin; Zhang, Yue; Xia, Qian; Bi, Wentao; Yang, Xiaodi; Chen, David Da Yong

    2016-04-22

    A fast environment-friendly extraction method, ball mill-assisted deep eutectic solvent-based extraction, was used for the extraction of natural products from plants. In this study, tanshinones were selected as target compounds to evaluate the efficiency of the developed extraction method. Under the optimized experimental conditions, cryptotanshinone (0.176 mg/g), tanshinone I (0.181 mg/g), and tanshinone II A (0.421 mg/g) were extracted from Salvia miltiorrhiza Bunge, and the developed method was found to be greener, more efficient, and faster than conventional, environmentally harmful extraction methods such as methanol-based ultrasound-assisted extraction and heat reflux extraction. The analytical performances including recovery, reproducibility (RSD, n=5), correlation of determination (r(2)), and the limit of detection, with the ranges of 96.1-103.9%, 1.6-1.9%, 0.9973-0.9984, and 5-8 ng/mL, were respectively obtained. Application of ball mill-assisted deep eutectic solvent-based extraction may fundamentally shape the future development of extraction methods. PMID:27033981

  5. New Highly Mixed Phases in Ball-Milled Cu/ZnO Catalysts as Established by EXAFS and XANES

    SciTech Connect

    Grandjean, Didier; Weckhuysen, Bert M.; Castricum, Hessel L.; Heuvel, Johannes C. van den

    2007-02-02

    AnXAFS investigation at both the Cu and Zn K-edge has allowed to unravel new highly mixed phases in Cu/ZnO catalysts prepared by ball-milling mixtures of Cu2O and ZnO under 3 different atmospheres of synthetic air (SA), SA+CO2 and CO2. The system milled in CO2 shows the disproportionation of Cu2O into Cu0, Cu1+ (cuprite Cu2O-type phase) and Cu2+ (tenorite CuO-type phase), while most of the Zn2+ is transformed into a nanocrystalline / amorphous ZnO-type zincite that forms a superficial mixture of oxide and carbonate phases. When synthetic air is added to the CO2 atmosphere, ball-milling results in the oxidation of part of the Cu1+ into Cu2+ with no Cu metal formed. In SA, a significant amount of Cu2+- and Zn2+-based phases react to form a nanocrystalline / amorphous Cu1-xZnxO solid solution that was never reported before. This distorted rock salt-like solid solution, in which Zn and Cu feature different octahedral environments, is formed by incorporation of Zn2+ in the Cu2O matrix and the concomitant oxidation of Cu1+ into Cu2+ and results from strong Cu/Zn interactions in the Cu/ZnO system.

  6. Preparation of natural pyrite nanoparticles by high energy planetary ball milling as a nanocatalyst for heterogeneous Fenton process

    NASA Astrophysics Data System (ADS)

    Fathinia, Siavash; Fathinia, Mehrangiz; Rahmani, Ali Akbar; Khataee, Alireza

    2015-02-01

    In the present study pyrite nanoparticles were prepared by high energy mechanical ball milling utilizing a planetary ball mill. Various pyrite samples were produced by changing the milling time from 2 h to 6 h, in the constant milling speed of 320 rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) linked with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer-Emmett-Teller (BET) were performed to explain the characteristics of primary (unmilled) and milled pyrite samples. The average particle size distribution of the produced pyrite during 6 h milling was found to be between 20 nm and 100 nm. The catalytic performance of the different pyrite samples was examined in the heterogeneous Fenton process for degradation of C.I. Acid Orange 7 (AO7) solution. Results showed that the decolorization efficiency of AO7 in the presence of 6 h-milled pyrite sample was the highest. The impact of key parameters on the degradation efficiency of AO7 by pyrite nanoparticles catalyzed Fenton process was modeled using central composite design (CCD). Accordingly, the maximum removal efficiency of 96.30% was achieved at initial AO7 concentration of 16 mg/L, H2O2 concentration of 5 mmol/L, catalyst amount of 0.5 g/L and reaction time of 25 min.

  7. A comparison of cellulose nanocrystals and cellulose nanofibres extracted from bagasse using acid and ball milling methods

    NASA Astrophysics Data System (ADS)

    Rahimi Kord Sofla, M.; Brown, R. J.; Tsuzuki, T.; Rainey, T. J.

    2016-09-01

    This study compared the fundamental properties of cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) extracted from sugarcane bagasse. Conventional hydrolysis was used to extract CNC while ball milling was used to extract CNF. Images generated by scanning electron microscope and transmission electron microscope showed CNC was needle-like with relatively lower aspect ratio and CNF was rope-like in structure with higher aspect ratio. Fourier-transformed infrared spectra showed that the chemical composition of nanocellulose and extracted cellulose were identical and quite different from bagasse. Dynamic light scattering studies showed that CNC had uniform particle size distribution with a median size of 148 nm while CNF had a bimodal size distribution with median size 240 ± 12 nm and 10 μm. X-ray diffraction showed that the amorphous portion was removed during hydrolysis; this resulted in an increase in the crystalline portion of CNC compared to CNF. Thermal degradation of cellulose initiated at a much lower temperature, in the case of the nanocrystals while the CNF prepared by ball milling were not affected, indicating higher thermal stability.

  8. Enhanced lithium storage in ZnFe2O4-C nanocomposite produced by a low-energy ball milling

    NASA Astrophysics Data System (ADS)

    Thankachan, Rahul Mundiyaniyil; Rahman, Md Mokhlesur; Sultana, Irin; Glushenkov, Alexey M.; Thomas, Sabu; Kalarikkal, Nandakumar; Chen, Ying

    2015-05-01

    Preparation of novel nanocomposite structure of ZnFe2O4-C is achieved by combining a sol-gel and a low energy ball milling method. The crucial feature of the composite's structure is that sol-gel synthesised ZnFe2O4 nanoparticles are dispersed and attached uniformly along the chains of Super P Li™ carbon black matrix by adopting a low energy ball milling. The composite ZnFe2O4-C electrodes are capable of delivering a very stable reversible capacity of 681 mAh g-1 (96% retention of the calculated theoretical capacity of ∼710 mAh g-1) at 0.1 C after 100 cycles with a remarkable Coulombic efficiency (82%) improvement in the first cycle. The rate capability of the composite is significantly improved and obtained capacity was as high as 702 at 0.1, 648 at 0.5, 582 at 1, 547 at 2 and 469 mAh g-1 at 4 C (2.85 A g-1), respectively. When cell is returned to 0.1 C, the capacity recovery was still ∼98%. Overall, the electrochemical performance (in terms of cycling stability, high rate capability, and capacity retention) is outstanding and much better than those of the related reported works. Therefore, our smart electrode design enables ZnFe2O4-C sample to be a high quality anode material for lithium-ion batteries.

  9. Effects of process control agent on the synthesis of AIN-carbon nanotube by ball-milling.

    PubMed

    Nam, Hye Rim; Kim, Young Jin; Ahn, Jung-Ho

    2013-09-01

    Aluminum and its alloy are of importance due to high specific strength. In particular, aluminum matrix composites have good corrosion resistance and mechanical property at high temperatures. However, enhanced mechanical strength and wear resistance via proper heat treatments are strongly required for many structural applications. For this purpose, we synthesized carbon nanotube (CNT)-reinforced aluminum matrix composites by employing a new method. We employed controlled ball-milling and sintering: the use of some specific process control agents (PCAs) for ball-milling and sintering in a specific atmosphere. The use of our PCAs was beneficial both for homogeneous mixing and for the formation of hard dispersoids. Hardened layers was formed at the surface of the present aluminum-CNT composites as a result of reaction of aluminum with PCAs and nitrogen in the processing atmosphere. The resulting materials after sintering showed interesting mechanical properties, combined with surface hardening. The hardening mainly stems from the formation of Al-N-O phase at the surface of specimens. PMID:24205586

  10. Mechanical alloying of Si and Ge in a planetary ball mill: Milling parameters and microscopic evolution of alloy formation

    SciTech Connect

    Schilz, J.; Pixius, K.; Amend, W.; Plate, M.; Meyer, H.

    1994-08-10

    The external parameters geometry and frequency of a planetary ball mill were adjusted in order to minimize the duration of mechanically induced Si-Ge alloy formation. Experimental results were compared with theoretical calculations on impact energies and milling power. It was found that a planetary ball mill with a ratio of the planetary to the system wheel`s frequency of {minus}3 delivers the best milling performance for vial sizes between 0.2 and 0.33 that of the system wheel size. Microstructural investigations on powder compacts revealed that a solid state diffusion mechanism of Ge into the harder Si seems to be the responsible process for realizing a homogeneous Si-Ge alloy. Crystallite sizes of the processed powders were 30 nm. The knowledge of the influence of external milling parameters on the comminution and alloying behavior of substances and the resulting internal structure of the processed ingots may help in a future correlation between thermoelectrical properties and microstructure. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  11. Multiscale characterization and analysis of shapes

    DOEpatents

    Prasad, Lakshman; Rao, Ramana

    2002-01-01

    An adaptive multiscale method approximates shapes with continuous or uniformly and densely sampled contours, with the purpose of sparsely and nonuniformly discretizing the boundaries of shapes at any prescribed resolution, while at the same time retaining the salient shape features at that resolution. In another aspect, a fundamental geometric filtering scheme using the Constrained Delaunay Triangulation (CDT) of polygonized shapes creates an efficient parsing of shapes into components that have semantic significance dependent only on the shapes' structure and not on their representations per se. A shape skeletonization process generalizes to sparsely discretized shapes, with the additional benefit of prunability to filter out irrelevant and morphologically insignificant features. The skeletal representation of characters of varying thickness and the elimination of insignificant and noisy spurs and branches from the skeleton greatly increases the robustness, reliability and recognition rates of character recognition algorithms.

  12. GEL-STATE NMR OF BALL-MILLED WHOLE CELL WALLS IN DMSO-d6 USING 2D SOLUTION-STATE NMR SPECTROSCOPY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant cell walls were used for obtaining 2D solution-state NMR spectra without actual solubilization or structural modification. Ball-milled whole cell walls were swelled directly in the NMR tube with DMSO-d6 where they formed a gel. There are relatively few gel-state NMR studies. Most have involved...

  13. High performance amorphous-Si@SiOx/C composite anode materials for Li-ion batteries derived from ball-milling and in situ carbonization

    NASA Astrophysics Data System (ADS)

    Wang, Dingsheng; Gao, Mingxia; Pan, Hongge; Wang, Junhua; Liu, Yongfeng

    2014-06-01

    Amorphous-Si@SiOx/C composites with amorphous Si particles as core and coated with a double layer of SiOx and carbon are prepared by ball-milling crystal micron-sized silicon powders and carbonization of the citric acid intruded in the ball-milled Si. Different ratios of Si to citric acid are used in order to optimize the electrochemical performance. It is found that SiOx exists naturally at the surfaces of raw Si particles and its content increases to ca. 24 wt.% after ball-milling. With an optimized Si to citric acid weight ratio of 1/2.5, corresponding to 8.4 wt.% C in the composite, a thin carbon layer is coated on the surfaces of a-Si@SiOx particles, moreover, floc-like carbon also forms and connects the carbon coated a-Si@SiOx particles. The composite provides a capacity of 1450 mA h g-1 after 100 cycles at a current density of 100 mA g1, and a capacity of 1230 mA h g-1 after 100 cycles at 500 mA g1 as anode material for lithium-ion batteries. Effects of ball-milling and the addition of citric acid on the microstructure and electrochemical properties of the composites are revealed and the mechanism of the improvement in electrochemical properties is discussed.

  14. Manganese(III) Acetate-Promoted Cross-Coupling Reaction of Benzothiazole/Thiazole Derivatives with Organophosphorus Compounds under Ball-Milling Conditions.

    PubMed

    Li, Liang; Wang, Jun-Jie; Wang, Guan-Wu

    2016-07-01

    The first solvent-free manganese(III) acetate-promoted reaction of benzothiazole/thiazole derivatives with organophosphorus compounds including phosphine oxides, phosphinate ester, and phosphonate diester has been efficiently developed under ball-milling conditions, providing a highly efficient and green protocol to structurally diverse C2-phosphonylated benzothiazole/thiazole derivatives with remarkable functional group tolerance and excellent yields. PMID:27248000

  15. HRTEM and TEM studies of amorphous structures in ZrNiTiCu base alloys obtained by rapid solidification or ball milling.

    PubMed

    Dutkiewicz, J; Lityńska, L; Maziarz, W; Kocisko, R; Molnarová, M; Kovácová, A

    2009-01-01

    Amorphous structure of Ti(25)Zr(17)Ni(29)Cu(29) composition was studied. Alloys were prepared either by rapid solidification using melt spinning or by high-energy ball milling. The composition of multi-component eutectic in slowly cooled samples of ZrNiTiCu alloy was determined using EDS measurements in scanning microscope of slowly cooled cast samples. The alloys of eutectic composition were melt-spun or ball-milled. Transmission electron microscopy (TEM) studies of melt-spun ribbons from alloys near eutectic composition did not show presence of nanocrystals within the amorphous structure. TEM studies of ball-milled powders showed presence of nanocrystallites of size 2-5 nm. The electron diffraction pattern showed intense diffused ring due to the presence of the amorphous phase and a weak spot due to crystalline phases which were difficult to identify. The high temperature high-pressure compaction in vacuum of amorphous ball-milled powders resulted in a similar structure like in the powders showing nanocrystals embedded in the amorphous matrix. The crystallites were imaged using HREM. Interplanar distances were measured in pictures obtained by inverse fast Fourier transform (IFFT) of atomic planes to obtain better contrast. Analysis of the IFFT from high-resolution micrographs allowed to identify Cu(10)Zr(7) phase. Point analysis and elemental mapping performed using nondispersive X-ray energy spectroscopy showed uniform elements distribution indicating that chemical segregation to nanocrystals is within measurement error. PMID:18614372

  16. Superthermostability of nanoscale TIC-reinforced copper alloys manufactured by a two-step ball-milling process

    NASA Astrophysics Data System (ADS)

    Wang, Fenglin; Li, Yunping; Xu, Xiandong; Koizumi, Yuichiro; Yamanaka, Kenta; Bian, Huakang; Chiba, Akihiko

    2015-12-01

    A Cu-TiC alloy, with nanoscale TiC particles highly dispersed in the submicron-grained Cu matrix, was manufactured by a self-developed two-step ball-milling process on Cu, Ti and C powders. The thermostability of the composite was evaluated by high-temperature isothermal annealing treatments, with temperatures ranging from 727 to 1273 K. The semicoherent nanoscale TiC particles with Cu matrix, mainly located along the grain boundaries, were found to exhibit the promising trait of blocking grain boundary migrations, which leads to a super-stabilized microstructures up to approximately the melting point of copper (1223 K). Furthermore, the Cu-TiC alloys after annealing at 1323 K showed a slight decrease in Vickers hardness as well as the duplex microstructure due to selective grain growth, which were discussed in terms of hardness contributions from various mechanisms.

  17. Nucleoside azide-alkyne cycloaddition reactions under solvothermal conditions or using copper vials in a ball mill.

    PubMed

    Cummings, Andrew J; Ravalico, Francesco; McColgan-Bannon, Kegan I S; Eguaogie, Olga; Elliott, P Alain; Shannon, Matthew R; Bermejo, Iris A; Dwyer, Angus; Maginty, Amanda B; Mack, James; Vyle, Joseph S

    2015-01-01

    Novel nucleoside analogues containing photoswitchable moieties were prepared using 'click' cycloaddition reactions between 5'-azido-5'-deoxythymidine and mono- or bis-N-propargylamide-substituted azobenzenes. In solution, high to quantitative yields were achieved using 5 mol% Cu(I) in the presence of a stabilizing ligand. 'Click' reactions using the monopropargylamides were also effected in the absence of added cuprous salts by the application of liquid assisted grinding (LAG) in metallic copper reaction vials. Specifically, high speed vibration ball milling (HSVBM) using a 3/32″ (2.38 mm) diameter copper ball (62 mg) at 60 Hz overnight in the presence of ethyl acetate lead to complete consumption of the 5'-azido nucleoside with clean conversion to the corresponding 1,3-triazole. PMID:25874944

  18. Investigations on electron beam evaporation of a ball-milled Cu(In1- x Ga x )Se2 powder

    NASA Astrophysics Data System (ADS)

    Alamri, S. N.; Alsadi, H. F.

    2015-07-01

    CuIn1- x Ga x Se (CIGS) powder was synthesized via the direct reaction of elemental copper, indium, gallium and selenium using ball milling. CIGS thin films were deposited onto glass substrates by using electron beam deposition at different substrate temperatures ranging from 200 ℃ to 500 ℃. The effect of substrate temperature on the structure, surface morphology and optical properties of the films were investigated by using X-ray diffraction, energy dispersive X-ray analysis, atomic force microscopy and optical spectroscopy. Increasing the substrate temperature improved the crystallinity of the films; in addition, the (112) preferred orientation became stronger, the grain size increased from 222 Å to 414 Å and the unit cell volume increased from 350.4 Å3 to 384.1 Å3. The stoichiometry of the films varied with the substrate temperature. The optical properties, band gap and refractive index were reduced as the substrate temperature was increased.

  19. Properties of dispersion-strengthened chromium - 4-volume-percent-thoria alloys produced by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1974-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol. %ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1537 C. Hot pressed Cr + ThO2 had a DBTT of 501 C as compared with minus 8 to 24 C for the hot rolled Cr + ThO2 and with 139 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  20. The structure and magnetic properties of Sm-Fe-N powders prepared by ball milling at low temperature

    NASA Astrophysics Data System (ADS)

    Fang, Qiuli; An, Xiaoxin; Wang, Fang; Li, Ying; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

    2016-07-01

    Sm-Fe-N powders have great potential to be used for preparing high-performance bonded permanent magnets because of their high anisotropy field and large saturation magnetization. In this work, we report the morphology, structure, oxygen content and magnetic properties of the Sm-Fe-N powders prepared by high energy ball milling at low temperature. Compared with the samples milled at room temperature, the Sm-Fe-N powders prepared at low temperature display more homogeneous morphology, less decomposition, lower oxygen content, and therefore enhanced magnetic performance. Our experimental results indicate that the low temperature milling will be a promising method for fabricating Sm-Fe-N bonded magnets with high-performance.

  1. Significantly improved dehydrogenation of ball-milled MgH2 doped with CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Shan, Jiawei; Li, Ping; Wan, Qi; Zhai, Fuqiang; Zhang, Jun; Li, Ziliang; Liu, Zhaojiang; Volinsky, Alex A.; Qu, Xuanhui

    2014-12-01

    CoFe2O4 nanoparticles are added to magnesium hydride (MgH2) by high-energy ball milling in order to improve its hydriding properties. The hydrogen storage properties and catalytic mechanism are investigated by pressure-composition-temperature (PCT), differential thermal analysis (DTA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nonisothermal desorption results show that the onset desorption temperature of the MgH2 + 7 mol% CoFe2O4 is 160 °C, which is 200 °C lower than of the as-received MgH2. The dehydrogenation process of the MgH2 doped with the CoFe2O4 nanoparticles includes two steps. DTA curves and XRD patterns reveal that a chemical reaction happens between MgH2 and CoFe2O4, forming the final products of the ternary combination, corresponding to Co3Fe7, MgO and Co. The onset desorption temperature of the ball-milled MgH2 doped with Co3Fe7, MgO and Co is about 260 °C, approximately 100 °C lower than the un-doped MgH2, demonstrating that the ternary combination (Co3Fe7, MgO, and Co) also has a great catalytic effect on the MgH2 hydrogen storage properties. It is also confirmed that the various methods of adding the ternary combination have different effects on the MgH2 hydriding-dehydriding process.

  2. Dielectric and photocatalytic properties of sulfur doped TiO{sub 2} nanoparticles prepared by ball milling

    SciTech Connect

    Jalalah, Mohammed; Faisal, M.; Bouzid, Houcine; Ismail, Adel A.; Al-Sayari, Saleh A.

    2013-09-01

    Graphical abstract: - Highlights: • Designing of visible light responsive photocatalyst utilizing ball milling. • Sulphur used as dopant in commercial TiO{sub 2} P25 at different atomic percentage. • S doping resulted in an intense increase in absorption in the visible light region. • Newly design photocatalyst exhibited excellent photocatalytic performance. • 0.11 at.% S-doped TiO{sub 2} shows 3-times higher activity than that of TiO{sub 2} P25. - Abstract: Sulfur (S) doped commercial TiO{sub 2} P-25 has been achieved by changing the amount of thiourea using ball milling technique. The results of XRD clearly reveal biphasial anatase and rutile mixtures for all prepared samples and doping of S does not change the morphology of the TiO{sub 2}. The optical absorption edge of S-doped TiO{sub 2} was red shifted with indirect bandgap energy of 2.8 eV. The dielectric studies confirm that the dielectric constant of TiO{sub 2} increases after doping, however it becomes more conductive. Newly designed S-doped TiO{sub 2} photocatalysts exhibited excellent photocatalytic performance for the degradation of methylene blue (MB) under visible light. The overall photocatalytic activity of 0.11 at.% S-doped TiO{sub 2} was significantly 3-times higher than that of commercial TiO{sub 2} P-25 and complete degradation of MB has taken place after 90 min of irradiation under visible light while only 35% dye degraded when the reaction has been carried out in the presence of undoped TiO{sub 2}.

  3. Preparation of ultrafine magnetic biochar and activated carbon for pharmaceutical adsorption and subsequent degradation by ball milling.

    PubMed

    Shan, Danna; Deng, Shubo; Zhao, Tianning; Wang, Bin; Wang, Yujue; Huang, Jun; Yu, Gang; Winglee, Judy; Wiesner, Mark R

    2016-03-15

    Ball milling was used to prepare two ultrafine magnetic biochar/Fe3O4 and activated carbon (AC)/Fe3O4 hybrid materials targeted for use in pharmaceutical removal by adsorption and mechanochemical degradation of pharmaceutical compounds. Both hybrid adsorbents prepared after 2h milling exhibited high removal of carbamazepine (CBZ), and were easily separated magnetically. These adsorbents exhibited fast adsorption of CBZ and tetracycline (TC) in the initial 1h. The biochar/Fe3O4 had a maximum adsorption capacity of 62.7mg/g for CBZ and 94.2mg/g for TC, while values obtained for AC/Fe3O4 were 135.1mg/g for CBZ and 45.3mg/g for TC respectively when data were fitted using the Langmuir expression. Solution pH values slightly affected the sorption of TC on the adsorbents, while CBZ sorption was almost pH-independent. The spent adsorbents with adsorbed CBZ and TC were milled to degrade the adsorbed pollutants. The adsorbed TC itself was over 97% degraded after 3h of milling, while about half of adsorbed CBZ were remained. The addition of quartz sand was found to improve the mechanochemical degradation of CBZ on biochar/Fe3O4, and its degradation percent was up to 98.4% at the dose of 0.3g quarts sand/g adsorbent. This research provided an easy method to prepare ultrafine magnetic adsorbents for the effective removal of typical pharmaceuticals from water or wastewater and degrade them using ball milling. PMID:26685062

  4. Inkjet-printed flexible organic thin-film thermoelectric devices based on p- and n-type poly(metal 1,1,2,2-ethenetetrathiolate)s/polymer composites through ball-milling

    PubMed Central

    Jiao, Fei; Di, Chong-an; Sun, Yimeng; Sheng, Peng; Xu, Wei; Zhu, Daoben

    2014-01-01

    In this article, we put forward a simple method for the synthesis of thermoelectric (TE) composite materials. Both n- and p-type composites were obtained by ball-milling the insoluble and infusible metal coordination polymers with other polymer solutions. The particle size, film morphology and composition were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The TE properties of the drop-cast composite film were measured at different temperatures. An inkjet-printed flexible device was fabricated and the output voltage and short-circuit current at various hot-side temperatures (Thot) and temperature gradients (ΔT) were tested. The composite material not only highly maintained the TE properties of the pristine material but also greatly improved its processability. This method can be extended to other insoluble and infusible TE materials for solution-processed flexible TE devices. PMID:24615147

  5. Multi-scale characterization of topographic anisotropy

    NASA Astrophysics Data System (ADS)

    Roy, S. G.; Koons, P. O.; Osti, B.; Upton, P.; Tucker, G. E.

    2016-05-01

    We present the every-direction variogram analysis (EVA) method for quantifying orientation and scale dependence of topographic anisotropy to aid in differentiation of the fluvial and tectonic contributions to surface evolution. Using multi-directional variogram statistics to track the spatial persistence of elevation values across a landscape, we calculate anisotropy as a multiscale, direction-sensitive variance in elevation between two points on a surface. Tectonically derived topographic anisotropy is associated with the three-dimensional kinematic field, which contributes (1) differential surface displacement and (2) crustal weakening along fault structures, both of which amplify processes of surface erosion. Based on our analysis, tectonic displacements dominate the topographic field at the orogenic scale, while a combination of the local displacement and strength fields are well represented at the ridge and valley scale. Drainage network patterns tend to reflect the geometry of underlying active or inactive tectonic structures due to the rapid erosion of faults and differential uplift associated with fault motion. Regions that have uniform environmental conditions and have been largely devoid of tectonic strain, such as passive coastal margins, have predominantly isotropic topography with typically dendritic drainage network patterns. Isolated features, such as stratovolcanoes, are nearly isotropic at their peaks but exhibit a concentric pattern of anisotropy along their flanks. The methods we provide can be used to successfully infer the settings of past or present tectonic regimes, and can be particularly useful in predicting the location and orientation of structural features that would otherwise be impossible to elude interpretation in the field. Though we limit the scope of this paper to elevation, EVA can be used to quantify the anisotropy of any spatially variable property.

  6. Phase development during high-energy ball-milling of zinc oxide and iron - the impact of grain size on the source and the degree of contamination.

    PubMed

    Štefanić, G; Krehula, S; Štefanić, I

    2015-11-21

    High-energy ball-milling of powder mixtures of zincite (ZnO) and iron (α-Fe) at different weight ratios was performed in air using a planetary ball mill with a stainless steel milling assembly. Structural and microstructural changes during the ball-milling (up to 30 h) were monitored using X-ray powder diffraction, field emission scanning electron microscopy (FE-SEM) and UV-Vis diffuse reflectance spectroscopy. The mechanism of iron oxidation was determined from the results of Mössbauer spectroscopy. It was found that an early phase of ball-milling caused the oxidation of iron from Fe(0) to Fe(2+) followed by the formation of a solid solution structurally similar to wüstite. The wüstite-type phase rapidly disappeared upon prolonged milling, which was accompanied by further oxidation of iron from Fe(2+) to Fe(3+) and the formation of spinel-type ferrite structurally similar to franklinite (ZnFe2O4) in the products with a high zinc content, or magnetite (Fe3O4) in the products with a high iron content. Further milling or annealing had a low impact on the franklinite-type phase, but caused the transition of the magnetite-type phase to the phase structurally similar to hematite (α-Fe2O3). The results of energy dispersive X-ray spectrometry (EDS) showed a dramatic increase in the degree of contamination with the increase in the proportion of the starting iron (∼9 times higher contamination during the milling of pure iron compared with pure zincite). It was shown that the source of contamination (balls or vial) strongly depends on the type of milled sample. Ball-milling of relatively big and heavy grains (starting iron) caused preferential contamination from the vial whereas ball-milling of smaller and lighter grains (products obtained after prolonged milling) caused preferential contamination from the balls. After prolonged milling the contamination due to wear of the balls was dominant in all the products. An explanation for the observed impact of grain size on

  7. Multiscale Approach to Characterize Mechanical Properties of Tissue Engineered Skin.

    PubMed

    Tupin, S; Molimard, J; Cenizo, V; Hoc, T; Sohm, B; Zahouani, H

    2016-09-01

    Tissue engineered skin usually consist of a multi-layered visco-elastic material composed of a fibrillar matrix and cells. The complete mechanical characterization of these tissues has not yet been accomplished. The purpose of this study was to develop a multiscale approach to perform this characterization in order to link the development process of a cultured skin to the mechanical properties. As a proof-of-concept, tissue engineered skin samples were characterized at different stages of manufacturing (acellular matrix, reconstructed dermis and reconstructed skin) for two different aging models (using cells from an 18- and a 61-year-old man). To assess structural variations, bi-photonic confocal microscopy was used. To characterize mechanical properties at a macroscopic scale, a light-load micro-mechanical device that performs indentation and relaxation tests was designed. Finally, images of the internal network of the samples under stretching were acquired by combining confocal microscopy with a tensile device. Mechanical properties at microscopic scale were assessed. Results revealed that adding cells during manufacturing induced structural changes, which provided higher elastic modulus and viscosity. Moreover, senescence models exhibited lower elastic modulus and viscosity. This multiscale approach was efficient to characterize and compare skin equivalent samples and permitted the first experimental assessment of the Poisson's ratio for such tissues. PMID:26942585

  8. Solvent-free cross-dehydrogenative coupling reactions under high speed ball-milling conditions applied to the synthesis of functionalized tetrahydroisoquinolines.

    PubMed

    Su, Weike; Yu, Jingbo; Li, Zhenhua; Jiang, Zhijiang

    2011-11-01

    Solvent-free reaction using a high-speed ball milling technique has been first applied to cross-dehydrogenative coupling (CDC) reactions between tetrahydroisoquinolines and three types of pronucleophiles such as nitroalkanes, alkynes, and indoles. All coupling products were obtained in good yields at short reaction times (no more than 40 min). When alkynes and indoles were used as pronucleophile, the reactions can be catalyzed efficiently by recoverable copper balls without any additional metal catalyst. PMID:21961457

  9. Sinterability and ionic conductivity of coprecipitated Ce 0.8Gd 0.2O 2- δ powders treated via a high-energy ball-milling process

    NASA Astrophysics Data System (ADS)

    Zhang, T. S.; Ma, J.; Kong, L. B.; Hing, P.; Leng, Y. J.; Chan, S. H.; Kilner, J. A.

    Ceria-based solid solutions are promising electrolytes for intermediate-temperature, solid oxide fuel cells. The effect of a dry, high-energy, ball-milling process on the sintering and densification behaviour of coprecipitated ceria-based powders is investigated by means of X-ray diffraction, Brunauer-Emmett-Teller (BET) surface-area measurements, density measurements, and electron microscopy. The dry ball-milling process leads to (i) a larger specific surface-area with weak agglomeration; (ii) rearrangement of grains into dense granules; (iii) a higher green density. These effects significantly reduce sintering temperatures and promote densification of ceria-based ceramics. Moreover, a comparison is made of the sintering behaviour and ionic conductivity of the milled samples with and without cobalt oxide doping. Cobalt oxide is a very effective sintering aid, but usually results in an enlarged grain-boundary effect for Si-containing samples. Thus, since SiO 2 is a ubiquitous background impurity in both raw materials and ceramic processing, the dry ball-milling process is a more feasible method for improving the sinterability of coprecipitated ceria-based powders.

  10. Solid-state synthesis of Mg{sub 2}Si via short-duration ball-milling and low-temperature annealing

    SciTech Connect

    Ioannou, M.; Chrissafis, K.; Pavlidou, E.; Gascoin, F.; Kyratsi, Th.

    2013-01-15

    In this work, a short duration ball-milling of elemental Mg and Si followed by a thermal treatment is suggested in order to synthesize magnesium silicide via solid-state reaction. The formation of magnesium silicide was studied in terms of its structure and thermal characteristics by powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and differential scanning calorimetry. Pure Mg{sub 2}Si was formed after short milling and heating at temperatures as low as 280 Degree-Sign C. Differential scanning calorimetry analysis was performed to study the kinetics of the reaction. The activation energy of the reaction was calculated using the Ozawa-Flynn-Wall and Friedman methods. The thermoelectric properties suggested semiconducting behavior whereas thermal conductivity values of highly dense hot-pressed pellets are consistent with the literature. - Graphical abstract: Thermographs of ball-milled Mg and Si powders (1 and 2) show exothermic areas suggesting Mg{sub 2}Si formation at low temperatures. Unmilled Mg and Si mixture (3) forms Mg{sub 2}Si at higher temperatures. Highlights: Black-Right-Pointing-Pointer Ball-milling process is crucial for the formation of pure Mg{sub 2}Si at low temperatures. Black-Right-Pointing-Pointer Synthesis profiles based on different temperature settings and duration are suggested. Black-Right-Pointing-Pointer Thermal analysis confirms the shift of the Mg{sub 2}Si formation at low temperatures.

  11. Synthesis of Nd2Fe14C compound by high-energy ball-milling Nd–Fe alloy in heptane and annealing under vacuum

    NASA Astrophysics Data System (ADS)

    Geng, H. M.; Ji, Y.; Feng, X. Y.; Zhang, J. J.; Ran, Z.; Yan, Y.; Wang, W. Q.; Su, F.; Du, X. B.

    2016-06-01

    A simple synthesis route for the Nd2Fe14C compound with good permanent magnetic properties is presented. Being high-energy ball-milled in heptane (C7H16) for 8 h, the NdFe3.5 alloy consisting of Nd2Fe17 and Nd phases disproportionates into NdH2+δ and α-Fe. Subsequently, NdH2+δ decomposes when annealed from room temperature to 900 °C under vacuum, and H2 is released. Meanwhile Nd2Fe14C, NdC and little α-Fe phases are formed in the final product. H and C atoms come from the decomposition of heptane. Coercivity of 1.39 T and maximum magnetic energy product of 62.7 kJ m‑3 have been achieved. Too short a ball-milling time results in the insufficient disproportionation of NdFe3.5 alloy and the residue of Nd2Fe17 phase in the final product. Too long a ball-milling time results in the appearance of NdC2 and more α-Fe phases besides Nd2Fe14C and NdC phases. Hexane (C6H14), octane (C8H18) and nonane (C9H20) have been proved to have a similar effect to heptane.

  12. Crystallographic alignment evolution and magnetic properties of anisotropic Sm0.6Pr0.4Co5 nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Xu, M. L.; Wu, Q.; Li, Y. Q.; Liu, W. Q.; Lu, Q. M.; Yue, M.

    2015-08-01

    The microstructure, crystal structure and magnetic properties were studied for Sm0.6Pr0.4Co5 nanoflakes prepared by surfactant-assisted high-energy ball milling (SAHEBM). Effect of ball-milling time on the c-axis crystallographic alignment, morphology and magnetic properties of Sm0.6Pr0.4Co5 nanoflakes was systematically investigated. With increasing milling time from 1 h to 7 h, the intensity ratio between (002) and (111) reflection peaks indicating degree of c-axis crystal texture of the (Sm, Pr)Co5 phase increases first, peaks at 3 h, then drops again, revealing that the strongest c-axis crystal texture was obtained in the nanoflakes milled for 3 h. On the other hand, the coercivity (Hci) of the flakes increases gradually from 1.71 to 14.65 kOe with the increase of ball milling time. As a result, an optimal magnetic properties of Mr of 10.23 kGs, Hci of 11.45 kOe and (BH)max of 24.40 MGOe was obtained in Sm0.6Pr0.4Co5 nanoflakes milled for 3 h, which also displayed a high aspect ratio, small in-plane size, pronounced (001) out-of-plane texture.

  13. Magnetically enhanced hard-soft SmCo5-FeNi composites obtained via high energy ball milling and heat treatment

    NASA Astrophysics Data System (ADS)

    Rai, B. K.; Mishra, S. R.

    2013-10-01

    The effect of high energy ball milling on the structure and magnetic properties of SmCo5-x%FeNi (x: 5,15), magnetically hard-soft phase composites, has been investigated as a function of composition ratio, ball milling time, and annealing temperature using x-ray diffraction and room temperature magnetometry. The milling resulted in decomposition of SmCo5 and FeNi phases. Heat treatment of ball-milled composites resulted in a secondary soft magnetic phase FeCo. High remanence and coercivity values are obtained at a low annealing temperature of ˜650 °C and short annealing time (20 min). Magnetic measurements of annealed composite sample, SmCo5-5%FeNi, show enhancement in magnetization (178%), remanence (127%), and coercivity (67%) as compared to that of pure SmCo5. The enhancement in coercivity and remanence is attributed to the effective exchange coupling between hard SmCo5 and soft FeCo/FeNi phases. Overall better magnetic properties were presented by composites with low FeNi content. The facile synthesis process represents a general process toward SmCo5 based exchange-spring nanocomposites for high performance bulk permanent magnet.

  14. Quantification of residual crystallinity in ball milled commercially sourced lactose monohydrate by thermo-analytical techniques and terahertz spectroscopy.

    PubMed

    Smith, Geoff; Hussain, Amjad; Bukhari, Nadeem Irfan; Ermolina, Irina

    2015-05-01

    The quantification of crystallinity is necessary in order to be able to control the milling process. The use of thermal analysis for this assessment presents certain challenges, particularly in the case of crystal hydrates. In this study, the residual crystallinity on ball milling of lactose monohydrate (LMH), for periods up to 90min, was evaluated by thermo-analytical techniques (TGA, DSC) and terahertz spectroscopy (THz). In general, the results from one of the DSC analysis and the THz measurements agree showing a monotonous decrease in relative residual crystallinity with milling time (∼80% reduction after 60min milling) and a slight increase at the 90min time point. However, the estimates from TGA and two other methods of analyzing DSC curve do not agree with the former techniques and show variability with significantly higher estimates for crystallinity. It was concluded that, the thermal techniques require more complex treatment of the data in the evaluation of changes in crystallinity of a milled material (in particular to account for the de-vitrification and mutarotation of the material that inevitably occurs during the measurement cycle) while the analysis of THz data is more straightforward, with the measurement having no impact on the native state of the material. PMID:25784570

  15. Textured PrCo{sub 5} nanoflakes with large coercivity prepared by low power surfactant-assisted ball milling

    SciTech Connect

    Zuo, Wen-Liang Liu, Rong-Ming; Zheng, Xin-Qi; Wu, Rong-Rong; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2014-05-07

    The effect of the milling time on the structure, morphology, coercivity, and remanence ratio of textured PrCo{sub 5} nanoflakes produced by low power surfactant-assisted ball milling (SABM) was investigated. The X-ray powder diffraction (XRD) patterns indicate that the SABM PrCo{sub 5} samples are all CaCu{sub 5}-type hexagonal structure. The average grain size is smaller than 10 nm when the SABM time is equal to or longer than 5.5 h. The thickness of nanoflakes is mainly in the range of 50−100 nm while the length is 0.5−5 μm when the SABM time reaches 8 h. For the field-aligned PrCo{sub 5} nanoflakes, the out-of-plane texture is indicated from the increasing (0 0 l) peaks in the XRD patterns, and the easy magnetization direction is perpendicular to the flake surface. The strong texture of PrCo{sub 5} nanoflakes leads to a large coercivity H{sub c} (7.8 kOe) and obvious anisotropic magnetic behaviors for the aligned samples.

  16. Photocatalytic enhancement of hybrid C3N4/TiO2 prepared via ball milling method.

    PubMed

    Zhou, Jianwei; Zhang, Mo; Zhu, Yongfa

    2015-02-01

    C3N4/TiO2 hybrid photocatalysts with highly enhanced photocatalytic performance were prepared by a facile ball milling method. A layered structure of g-C3N4 was formed on the surface of TiO2. The mechanochemical process can promote the dispersion of C3N4 on the surface of TiO2 particles, to form a single layer hybrid structure and a multi-layer core-shell structure. The photocatalytic activities of C3N4/TiO2 under visible and UV light irradiation were 3.0 and 1.3 times those of pure g-C3N4 and TiO2, respectively. Under visible light and UV irradiation, the photocurrent response was up to 2.5 times and 1.5 times as high as that of the pure TiO2 and C3N4, respectively. The evident performance enhancement of g-C3N4-TiO2 was mainly attributed to high separation and migration efficiency of electron-hole pairs. PMID:25553728

  17. A novel combined pretreatment of ball milling and microwave irradiation for enhancing enzymatic hydrolysis of microcrystalline cellulose.

    PubMed

    Peng, Huadong; Li, Hongqiang; Luo, Hao; Xu, Jian

    2013-02-01

    Microcrystalline cellulose (MCC) was performed as a mode substrate to investigate its potential ability of bioconversion in a novel combined pretreatment of ball milling (BM) and/or microwave irradiation (MWI). The variation of structure characteristics of MCC before/after pretreatment were investigated, including crystallinity index (CrI), size of crystal (S(C)), specific surface area (SSA) and degree of polymerization (DP). Their correlation with the rate of enzymatic hydrolysis was differentiated by an optimized equation which indicated the rate of hydrolysis was much more sensitive to CrI than SSA and DP. To achieve the same or higher glucose yield of BM for 3h and 6h, BM for 1h with MWI for 20min could save 54.8% and 77.40% energy consumption, respectively. Moreover, chemicals were not required in this process. It is concluded that the combination of BM and short time MWI is an environment-friendly, economical and effective approach to treat biomass. PMID:23306114

  18. Effects of high-energy ball-milling on injectability and strength of β-tricalcium-phosphate cement.

    PubMed

    Bae, Jiyoung; Ida, Yumika; Sekine, Kazumitsu; Kawano, Fumiaki; Hamada, Kenichi

    2015-07-01

    Calcium phosphate cement (CPC) offers many advantages as a bone-substitution material. The objective of this study is to develop a new CPC that simultaneously exhibits fine injectability, a short setting time, and high strength. β-tricalcium phosphate (β-TCP, control) powder was ball-milled for 24h to produce a new cement powder. The modified β-TCP after 24h milling (mβ-TCP-24h) exhibited excellent injectability even 1h after mixing. The mechanical properties of the set cement (compact) were evaluated using compressive strength (CS) and diametral tensile strength (DTS) testing. The CS and DTS values of the mβ-TCP-24h compacts were 8.02MPa and 2.62MPa, respectively, at 5h after mixing, and were 49.6MPa and 7.9MPa, respectively, at 2 weeks after mixing. All the CS and DTS values of the mβ-TCP-24h compacts were significantly higher than those of the control for the same duration after mixing. These results suggest that the mechano-chemically modified β-TCP powder dissolves rapidly and accelerates hydroxyapatite precipitation, which successfully shortens the cement setting time and enhances the strength. This study supports that mβ-TCP-24h is a promising candidate for use in injectable CPCs with improved strength. PMID:25855467

  19. DEM modeling of ball mills with experimental validation: influence of contact parameters on charge motion and power draw

    NASA Astrophysics Data System (ADS)

    Boemer, Dominik; Ponthot, Jean-Philippe

    2016-07-01

    Discrete element method simulations of a 1:5-scale laboratory ball mill are presented in this paper to study the influence of the contact parameters on the charge motion and the power draw. The position density limit is introduced as an efficient mathematical tool to describe and to compare the macroscopic charge motion in different scenarios, i.a. with different values of the contact parameters. While the charge motion and the power draw are relatively insensitive to the stiffness and the damping coefficient of the linear spring-slider-damper contact law, the coefficient of friction has a strong influence since it controls the sliding propensity of the charge. Based on the experimental calibration and validation by charge motion photographs and power draw measurements, the descriptive and predictive capabilities of the position density limit and the discrete element method are demonstrated, i.e. the real position of the charge is precisely delimited by the respective position density limit and the power draw can be predicted with an accuracy of about 5 %.

  20. Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling.

    PubMed

    Hashishin, Takeshi; Tan, Zhenquan; Yamamoto, Kazuhiro; Qiu, Nan; Kim, Jungeum; Numako, Chiya; Naka, Takashi; Valmalette, Jean Christophe; Ohara, Satoshi

    2014-01-01

    The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase. PMID:24763088

  1. High-Efficient Production of Boron Nitride Nanosheets via an Optimized Ball Milling Process for Lubrication in Oil

    NASA Astrophysics Data System (ADS)

    Deepika; Li, Lu Hua; Glushenkov, Alexey M.; Hait, Samik K.; Hodgson, Peter; Chen, Ying

    2014-12-01

    Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

  2. Grinding Wear Behaviour of Stepped Austempered Ductile Iron as Media Material During Comminution of Iron Ore in Ball Mills

    SciTech Connect

    Raghavendra, H.; Bhat, K. L.; Udupa, K. Rajendra; Hegde, M. M. Rajath

    2011-01-17

    An attempt has been made to evaluate the suitability of austempered ductile iron (ADI) as media material for grinding iron ore in a ball mill. Spheroidal graphite (S.G) iron balls are austenitised at 900 deg. C for 60 minutes and given stepped austempering treatment at 280 deg. C for 30 minutes and 60 minutes followed by 380 deg. C for 60 minutes in each case. These materials are characterised by measuring hardness, analysing X-ray diffraction (X-RD), studying microstructure using optical and scanning electron microscope (SEM). Grinding wear behaviour of these materials was assessed for wear loss in wet condition at different pH value of the mineral slurry and found that the wear rate of grinding media material decreases with increase in pH of the slurry. The wear resistance of ADI balls were compared with forged En31 steel balls and found that the stepped austempered ductile iron is superior to forged En31 steel balls.

  3. Preparation of CNT/AlSi10Mg composite powders by high-energy ball milling and their physical properties

    NASA Astrophysics Data System (ADS)

    Wang, Lin-zhi; Liu, Ying; Wei, Wen-hou; An, Xu-guang; Zhang, Tao; Pu, Ya-yun

    2016-03-01

    This study investigated the effects of carbon nanotube (CNT) concentration on the micro-morphologies and laser absorption properties of CNT/AlSi10Mg composite powders produced by high-energy ball milling. A scanning electron microscope, X-ray diffractometer, laser particle size analyzer, high-temperature synchronous thermal analyzer, and UV/VIS/NIR spectrophotometer were used for the analysis of micrographs, phases, granulometric parameters, thermal properties, and laser absorption properties of the composite powders, respectively. The results showed that the powders gradually changed from flake- to granule-like morphology and the average particle size sharply decreased with increases in milling rotational speed and milling time. Moreover, a uniform dispersion of CNTs in AlSi10Mg powders was achieved only for a CNT content of 1.5wt%. Laser absorption values of the composite powders were also observed to gradually increase with the increase of CNT concentration, and different spectra displayed characteristic absorption peaks at a wavelength of approximately 826 nm.

  4. Multiscale geophysical characterization of an unstable rock mass

    NASA Astrophysics Data System (ADS)

    Colombero, Chiara; Comina, Cesare; Umili, Gessica; Vinciguerra, Sergio

    2016-04-01

    Hazard mitigation from rockfalls and landslides is a priority in densely populated areas. A proper characterization of the inner structure of the rock mass is key to the comprehension of the mechanisms enhancing the slope instabilities. To this aim multi-scale geophysical methods can provide a novel and valuable tool for a high-resolution imaging of the internal structure of the rock mass and unique constraints on the physical state of the medium. We present here a cross-hole seismic tomography survey coupled with laboratory ultrasonic velocity measurements and physical properties determination on rock samples to characterize the damaged and potentially unstable granitic cliff of Madonna del Sasso (NW Italy). Results allowed to obtain: i) a lithological interpretation of the velocity field obtained at the site, ii) a systematic correlation of the measured velocities with physical properties (density and porosity) and macroscopic features of the granite (weathering and anisotropy) of the cliff. The multi-scale approach adopted within this study revealed to be crucial for the imaging at depth of the main fractures affecting the cliff (site-scale seismic tests) and for the understanding of the variations in the seismic velocity between altered and intact rock (laboratory-scale tests); similar approaches can be potentially used in further microseismic monitoring studies.

  5. Multiscale characterization and representation of composite materials during processing.

    PubMed

    Zobeiry, Navid; Forghani, Alireza; Li, Chao; Gordnian, Kamyar; Thorpe, Ryan; Vaziri, Reza; Fernlund, Goran; Poursartip, Anoush

    2016-07-13

    Given the importance of residual stresses and dimensional changes in composites manufacturing, process simulation has been the focus of many studies in recent years. Consequently, various constitutive models and simulation approaches have been developed and implemented for composites process simulation. In this paper, various constitutive models, ranging from elastic to nonlinear viscoelastic; and simulation approaches ranging from separated flow/solid phases to multiscale integrated phases are presented and their applicability for process simulation is discussed. Attention has been paid to practical aspects of the problem where the complexity of the model coupled with the complexity and size scaling of the structure increases the characterization and simulation costs. Two specific approaches and their application are presented in detail: the pseudo-viscoelastic cure hardening instantaneously linear elastic (CHILE) and linear viscoelastic (VE). It is shown that CHILE can predict the residual stress formation in simple cure cycles such as the one-hold cycle for HEXCEL AS4/8552 where the material does not devitrify during processing. It is also shown that using this simple approach, the cure cycle can be modified to lower the residual stress level and therefore increase the mechanical performance of the composite laminate. For a more complex cure cycle where the material is devitrified during a post-cure, it is shown that a more complex model such as VE is required. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242297

  6. Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability.

    PubMed

    Bao, Di; Gao, Peng; Shen, Xiande; Chang, Cheng; Wang, Longqiang; Wang, Ying; Chen, Yujin; Zhou, Xiaoming; Sun, Shuchao; Li, Guobao; Yang, Piaoping

    2014-02-26

    The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process. PMID:24498904

  7. A comparison of the amorphization of zeolitic imidazolate frameworks (ZIFs) and aluminosilicate zeolites by ball-milling.

    PubMed

    Baxter, Emma F; Bennett, Thomas D; Cairns, Andrew B; Brownbill, Nick J; Goodwin, Andrew L; Keen, David A; Chater, Philip A; Blanc, Frédéric; Cheetham, Anthony K

    2016-03-14

    X-ray diffraction has been used to investigate the kinetics of amorphization through ball-milling at 20 Hz, for five zeolitic imidazolate frameworks (ZIFs) - ZIF-8, ZIF-4, ZIF-zni, BIF-1-Li and CdIF-1. We find that the rates of amorphization for the zinc-containing ZIFs increase with increasing solvent accessible volume (SAV) in the sequence ZIF-8 > ZIF-4 > ZIF-zni. The Li-B analogue of the dense ZIF-zni amorphizes more slowly than the corresponding zinc phase, with the behaviour showing a correlation with their relative bulk moduli and SAVs. The cadmium analogue of ZIF-8 (CdIF-1) amorphizes more rapidly than the zinc counterpart, which we ascribe primarily to its relatively weak M-N bonds as well as the higher SAV. The results for the ZIFs are compared to three classical zeolites - Na-X, Na-Y and ZSM-5 - with these taking up to four times longer to amorphize. The presence of adsorbed solvent in the pores is found to render both ZIF and zeolite frameworks more resistant to amorphization. X-ray total scattering measurements show that amorphous ZIF-zni is structurally indistinguishable from amorphous ZIF-4 with both structures retaining the same short-range order that is present in their crystalline precursors. By contrast, both X-ray total scattering measurements and (113)Cd NMR measurements point to changes in the local environment of amorphous CdIF-1 compared with its crystalline CdIF-1 precursor. PMID:26575842

  8. Multiscale characterization of dislocation processes in Al 5754

    NASA Astrophysics Data System (ADS)

    Kacher, Josh; Mishra, Raja K.; Minor, Andrew M.

    2015-07-01

    Multiscale characterization was performed on an Al-Mg alloy, Al 5754 O-temper, including in situ mechanical deformation in both the scanning electron microscope and the transmission electron microscope. Scanning electron microscopy characterization showed corresponding inhomogeneity in the dislocation and Mg distribution, with higher levels of Mg correlating with elevated levels of dislocation density. At the nanoscale, in situ transmission electron microscopy straining experiments showed that dislocation propagation through the Al matrix is characterized by frequent interactions with obstacles smaller than the imaging resolution that resulted in the formation of dislocation debris in the form of dislocation loops. Post-mortem chemical characterization and comparison to dislocation loop behaviour in an Al-Cr alloy suggests that these obstacles are small Mg clusters. Previous theoretical work and indirect experimental evidence have suggested that these Mg nanoclusters are important factors contributing to strain instabilities in Al-Mg alloys. This study provides direct experimental characterization of the interaction of glissile dislocations with these nanoclusters and the stress needed for dislocations to overcome them.

  9. Hyperchaotic qualities of the ball motion in a ball milling device

    NASA Astrophysics Data System (ADS)

    Caravati, C.; Delogu, F.; Cocco, G.; Rustici, M.

    1999-03-01

    Ball collisions in milling devices are governed by complex dynamics ruled by impredictable impulsive forces. In this paper, nonlinear dynamics techniques are employed to analyze the time series describing the trajectory of a milling ball in an empty container obtained from a numerical model. The attractor underlying the system dynamics was reconstructed by the time delay method. In order to characterize the system dynamics the calculation of the spectrum of Lyapunov exponents was performed. Six Lyapunov exponents, divided into two terns with opposite sign, were obtained. The detection of the positive tern demonstrates the occurrence of the hyperchaotic qualities of the ball motion. A fractal Lyapunov dimension, equal to 5.62, was also obtained confirming the strange features of the attractor.

  10. Hyperchaotic qualities of the ball motion in a ball milling device.

    PubMed

    Caravati, C.; Delogu, F.; Cocco, G.; Rustici, M.

    1999-03-01

    Ball collisions in milling devices are governed by complex dynamics ruled by impredictable impulsive forces. In this paper, nonlinear dynamics techniques are employed to analyze the time series describing the trajectory of a milling ball in an empty container obtained from a numerical model. The attractor underlying the system dynamics was reconstructed by the time delay method. In order to characterize the system dynamics the calculation of the spectrum of Lyapunov exponents was performed. Six Lyapunov exponents, divided into two terns with opposite sign, were obtained. The detection of the positive tern demonstrates the occurrence of the hyperchaotic qualities of the ball motion. A fractal Lyapunov dimension, equal to 5.62, was also obtained confirming the strange features of the attractor. (c) 1999 American Institute of Physics. PMID:12779817

  11. Degradation of trichloroethene with a noval ball milled Fe-C nanocomposite

    SciTech Connect

    Gao, Jie; Wang, Wei; Rondinone, Adam Justin; He, Feng; Liang, Liyuan

    2015-07-18

    Nanoscale zero-valent iron (NZVI) is effective in reductively degrading dense non-aqueous phase liquids (DNAPLs), such as trichloroethene (TCE), in groundwater (i.e., dechlorination) although the NZVI technology itself still suffers from high material costs and inability to target hydrophobic contaminants in source zones. To address these problems, we developed a novel, inexpensive iron-carbon (Fe-C) nanocomposite material by simultaneously milling micron-size iron and activated carbon powder. Microscopic and X-ray diffraction (XRD) characterization of the composite material revealed that nanoparticles of Fe were dispersed in activated carbon and a new iron carbide phase was formed. Bench-scale studies showed that this material instantaneously sorbed >90% of TCE from aqueous solutions and subsequently decomposed TCE into non-chlorinated products. Compared to milled Fe, Fe-C nanocomposite dechlorinated TCE at a slightly slower rate and favored the production of ethene over other TCE degradation products such as C3-C6 compounds. When placed in hexane-water mixture, the Fe-C nanocomposite materials are preferentially partitioned into the organic phase, indicating the ability of the composite materials to target DNAPL during remediation.

  12. Degradation of trichloroethene with a noval ball milled Fe-C nanocomposite

    DOE PAGESBeta

    Gao, Jie; Wang, Wei; Rondinone, Adam Justin; He, Feng; Liang, Liyuan

    2015-07-18

    Nanoscale zero-valent iron (NZVI) is effective in reductively degrading dense non-aqueous phase liquids (DNAPLs), such as trichloroethene (TCE), in groundwater (i.e., dechlorination) although the NZVI technology itself still suffers from high material costs and inability to target hydrophobic contaminants in source zones. To address these problems, we developed a novel, inexpensive iron-carbon (Fe-C) nanocomposite material by simultaneously milling micron-size iron and activated carbon powder. Microscopic and X-ray diffraction (XRD) characterization of the composite material revealed that nanoparticles of Fe were dispersed in activated carbon and a new iron carbide phase was formed. Bench-scale studies showed that this material instantaneously sorbedmore » >90% of TCE from aqueous solutions and subsequently decomposed TCE into non-chlorinated products. Compared to milled Fe, Fe-C nanocomposite dechlorinated TCE at a slightly slower rate and favored the production of ethene over other TCE degradation products such as C3-C6 compounds. When placed in hexane-water mixture, the Fe-C nanocomposite materials are preferentially partitioned into the organic phase, indicating the ability of the composite materials to target DNAPL during remediation.« less

  13. Multiscale study for stochastic characterization of shale samples

    NASA Astrophysics Data System (ADS)

    Tahmasebi, Pejman; Javadpour, Farzam; Sahimi, Muhammad; Piri, Mohammad

    2016-03-01

    Characterization of shale reservoirs, which are typically of low permeability, is very difficult because of the presence of multiscale structures. While three-dimensional (3D) imaging can be an ultimate solution for revealing important complexities of such reservoirs, acquiring such images is costly and time consuming. On the other hand, high-quality 2D images, which are widely available, also reveal useful information about shales' pore connectivity and size. Most of the current modeling methods that are based on 2D images use limited and insufficient extracted information. One remedy to the shortcoming is direct use of qualitative images, a concept that we introduce in this paper. We demonstrate that higher-order statistics (as opposed to the traditional two-point statistics, such as variograms) are necessary for developing an accurate model of shales, and describe an efficient method for using 2D images that is capable of utilizing qualitative and physical information within an image and generating stochastic realizations of shales. We then further refine the model by describing and utilizing several techniques, including an iterative framework, for removing some possible artifacts and better pattern reproduction. Next, we introduce a new histogram-matching algorithm that accounts for concealed nanostructures in shale samples. We also present two new multiresolution and multiscale approaches for dealing with distinct pore structures that are common in shale reservoirs. In the multiresolution method, the original high-quality image is upscaled in a pyramid-like manner in order to achieve more accurate global and long-range structures. The multiscale approach integrates two images, each containing diverse pore networks - the nano- and microscale pores - using a high-resolution image representing small-scale pores and, at the same time, reconstructing large pores using a low-quality image. Eventually, the results are integrated to generate a 3D model. The methods

  14. Multiscale characterization of porous media properties for hydrocarbon reservoir simulation

    NASA Astrophysics Data System (ADS)

    Neeman, Henry; Lao, Hio-Wai; Simpson, Dale; Papavassiliou, Dimitrios V.

    2001-07-01

    Fluid flow through porous materials is critical for understanding and predicting the behavior of systems as diverse in function and scale as hydrocarbon reservoirs, aquifers, filters, membrane separators and even catalytic converters. Recently, there have been calls to incorporate more physics in oil reservoir simulations, as well as to enhance computational capability through the use of High Performance Computing (HPC), in order to improve reservoir management. Accurate prediction of reservoir behavior depends on the physical properties of not only the fluid but also the underlying rock formation. Contemporary approaches to solving these flows involve simulation of only a single physical scale. We are currently developing HiMuST (Hierarchical Multiscale Simulator Technology), an integrated multiscale simulation system for flow through heterogeneous porous materials. HiMuST uses a hierarchy of simulation codes to address the issue of rock property characterization at the pore scale and can self-adjust according to available input data. At the microscopic scale, HiMuST employs the Lattice Boltzmann Method, based on magnetic resonance digitizations of actual rock samples. At the mesoscopic scale, a stochastic model represents a pore network as a randomly generated skeleton of cylindrical pipes, based on physical characteristics determined by the microscopic simulation. We present computational and computer science issues involved in the HPC implementation of the codes and in integrating them into a seamless simulation system. Issues such as portability, scalability, efficiency and extensibility of the final product are also discussed, as well as the numerical methods implemented at each scale. Example simulation results are presented.

  15. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon

    2015-04-01

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na2CO3, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na2CO3, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4M HCl, 100°C and pulp density of 20g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. PMID:25769129

  16. Physical and electrochemical properties of LiFePO 4 nanoparticles synthesized by a combination of spray pyrolysis with wet ball-milling

    NASA Astrophysics Data System (ADS)

    Konarova, Muxina; Taniguchi, Izumi

    A novel preparation technique was developed to synthesize LiFePO 4 nanoparticles through a combination of spray pyrolysis (SP) with wet ball-milling (WBM). Using this technique, the preparation of LiFePO 4 nanoparticles was investigated for a wide range of process parameters such as ball-milling time and sintering temperature. The effect of process parameters on the physical and electrochemical properties of LiFePO 4 was then discussed through analysis using by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), the Brunauer-Emmet-Teller (BET) method, Raman spectroscopy and using an electrochemical cell of Li|1 M LiClO 4 in EC:DEC = 1:1|LiFePO 4. LiFePO 4 nanoparticles with a geometric mean diameter of 58 nm were prepared at a rotating speed of 800 rpm and a ball-milling time of 12 h in an Ar atmosphere followed by heat treatment at 500 °C for 4 h in a N 2 + 3% H 2 atmosphere. The sample delivered first discharge capacities of 164 and 100 mAh g -1 at charge-discharge rates of 0.1 and 10 C in the test cells, respectively. The electrochemical properties of LiFePO 4 nanoparticles were strongly affected by the formation of Fe 2P, Fe 3P and α-Fe 2O 3 at higher charge-discharge rates.

  17. Coercivity and superparamagnetic evolution of high energy ball milled (HEBM) bulk CoFe{sub 2}O{sub 4} material

    SciTech Connect

    Moyet, Richard Perez; Cardona, Yenny; Vargas, Pedro; Silva, Josue; Uwakweh, Oswald N.C.

    2010-12-15

    Ball milling (BM) of bulk CoFe{sub 2}O{sub 4} powder material carried out in order to study its structural stability and attendant property changes with respect to coercivity enhancements and superparamagnetic behaviors, showed that drastic crystallite size reduction occurred within the first 1 h of ball milling. Crystallite size dropped from 74 nm for the as-received material to a value of 11.6 nm for 600 min of ball milling. Combined X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed crystallite size reduction with corresponding increase in interparticle agglomeration/pores with increasing milling time. The maximum coercivity of 0.46 T and the crystallite size of 15.6 nm were recorded with 20 min, while peak residual strain of 0.0066 mm/mm was for 180 min of BM. Material with peak coercivity value did not have peak residual strain, or minimum crystallite size, thereby suggesting that other structural defects contributed to coercivity enhancement. The saturation magnetization (M{sub s}) value decreased continuously with increasing milling time, while remanence magnetization (M{sub r}) and coercivity decreased with increasing BM time, after an initial increase. Moessbauer spectroscopy (MS) measurements confirmed both particle size distribution and decomposition/disordering of the material together with superparamagnetism as BM time increased. The degree of inversion ranged from 41% to 71.7% at different milled states from Moessbauer spectroscopy. The internal magnetic fields of the Fe sites associated with the tetrahedral and octahedral sites were 507.4 kOe and 492 kOe respectively in the unmilled state, while 484 kOe and 468.5 kOe in the 600 min milled state correspondingly.

  18. Influence of ball milling on atomic structure and magnetic properties of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy alloy

    SciTech Connect

    Taghvaei, Amir Hossein; Stoica, Mihai; Bednarčik, Jozef; Kaban, Ivan; Shahabi, Hamed Shakur; Khoshkhoo, Mohsen Samadi; Janghorban, Kamal; Eckert, Jürgen

    2014-06-01

    The influence of ball milling on the atomic structure and magnetic properties of the Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} metallic glass with a high thermal stability and excellent soft magnetic properties has been investigated. After 14 h of milling, the obtained powders were found to consist mainly of an amorphous phase and a small fraction of the (Co,Fe){sub 21}Ta{sub 2}B{sub 6} nanocrystals. The changes in the reduced pair correlation functions suggest noticeable changes in the atomic structure of the amorphous upon ball milling. Furthermore, it has been shown that milling is accompanied by introduction of compressive and dilatational sites in the glassy phase and increasing the fluctuation of the atomic-level hydrostatic stress without affecting the coordination number of the nearest neighbors. Ball milling has decreased the thermal stability and significantly affected the magnetic properties through increasing the saturation magnetization, Curie temperature of the amorphous phase and coercivity. - Highlights: • Ball milling affected the atomic structure of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} metallic glass. • Mechanically-induced crystallization started after 4 h milling. • Milling increased the fluctuation of the atomic-level hydrostatic stress in glass. • Ball milling influenced the thermal stability and magnetic properties.

  19. Structural; magnetic and catalytic properties of nanocrystalline Cu0.5Zn0.5Fe2O4 synthesized by microwave combustion and ball milling methods

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. H.; Hassan, Azza M.; Said, Abd El-Aziz A.; Hamdeh, H. H.

    2016-06-01

    Effects of high energy ball-milling on nanosized Cu0.5Zn0.5Fe2O4 powders were studied at 30 and 330 min of milling. The powders were initially synthesized from its stoichiometric metal nitrates and urea mixtures, using a microwave assisted combustion method. Ball-milling induced electromechanical reaction was examined by XRD, TEM, Mössbauer spectroscopy, magnetization, and catalytic performance by exploring potential changes in size, phases and chemical structure. Before Milling, the as-prepared powders were comprised of small grains of poor spinel crystallinity and very small crystallite size, and a minor α-Fe2O3 phase. Progressive milling significantly reduced the grain size, increased chemical disorder, and reduced the hematite phase. These changes are also manifested in the magnetization measurements. The Catalytic activity performance was carried out using dehydrogenation of isopropyl alcohol. The observed activity was correlated to the presence of Cu2+ and Fe3+ catalysts at octahedral sites before and after milling.

  20. Multiscale characterization of a heterogeneous aquifer using an ASR operation.

    PubMed

    Pavelic, Paul; Dillon, Peter J; Simmons, Craig T

    2006-01-01

    Heterogeneity in the physical properties of an aquifer can significantly affect the viability of aquifer storage and recovery (ASR) by reducing the recoverable proportion of low-salinity water where the ambient ground water is brackish or saline. This study investigated the relationship between knowledge of heterogeneity and predictions of solute transport and recovery efficiency by combining permeability and ASR-based tracer testing with modeling. Multiscale permeability testing of a sandy limestone aquifer at an ASR trial site showed that small-scale core data give lower-bound estimates of aquifer hydraulic conductivity (K), intermediate-scale downhole flowmeter data offer valuable information on variations in K with depth, and large-scale pumping test data provide an integrated measure of the effective K that is useful to constrain ground water models. Chloride breakthrough and thermal profiling data measured during two cycles of ASR showed that the movement of injected water is predominantly within two stratigraphic layers identified from the flowmeter data. The behavior of the injectant was reasonably well simulated with a four-layer numerical model that required minimal calibration. Verification in the second cycle achieved acceptable results given the model's simplicity. Without accounting for the aquifer's layered structure, high precision could be achieved on either piezometer breakthrough or recovered water quality, but not both. This study demonstrates the merit of an integrated approach to characterizing aquifers targeted for ASR. PMID:16556198

  1. Multiscale characterization of partially demineralized superficial and deep dentin surfaces.

    PubMed

    Pelin, Irina M; Trunfio-Sfarghiu, Ana-Maria; Farge, Pierre; Piednoir, Agnes; Pirat, Christophe; Ramos, Stella M M

    2013-08-01

    The objective of this study was to address the following question: 'Which properties are modified in partially demineralized surfaces, compared with non-demineralized dentin surfaces, following orthophosphoric acid-etching as performed in clinical procedures?'. For this purpose, the complementary techniques atomic force microscopy/spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements were used to provide a multiscale characterization of the dentin substrate undergoing the acidic preconditioning designed to enhance wetting. Special attention was given to the influence of the etching pretreatment on the nanomechanical properties at different levels of dentin surfaces, in both dry and hydrated conditions. The four-sided pyramid model (extended Hertz contact model) proved to be accurate for calculating the apparent Young's modulus, offering new information on the elasticity of dentin. The modulus value notably decreased following etching and surface hydration. This study underlines that after the acid etching pretreatment the contribution of the nanomechanical, morphological, and physicochemical modifications has a strong influence on the dentin adhesion properties and thus plays a significant role in the coupling of the adhesive-resin composite build-up material at the dentin surface. PMID:23841786

  2. Multi-scale characterization of nanostructured sodium aluminum hydride

    NASA Astrophysics Data System (ADS)

    NaraseGowda, Shathabish

    Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to improve in performance and reversibility. This area of research has garnered immense interest lately and there is active research being pursued to address various aspects of nanostructured complex hydrides. The research effort documented here is focused on a detailed investigation of the effects of nano-confinement on aspects such as the long range atomic hydrogen diffusivities, localized hydrogen dynamics, microstructure, and dehydrogenation mechanism of sodium alanate. A wide variety of microporous and mesoporous materials (metal organic frameworks, porous silica and alumina) were investigated as scaffolds and the synthesis routes to achieve maximum pore-loading are discussed. Wet solution infiltration technique was adopted using tetrahydrofuran as the medium and the precursor concentrations were found to have a major role in achieving maximum pore loading. These concentrations were optimized for each scaffold with varying pore sizes and confinement was quantitatively characterized by measuring the loss in specific surface area. This work is also aimed at utilizing neutron and synchrotron x-ray characterization techniques to study and correlate multi-scale material properties and phenomena. Some of the most advanced

  3. Multiscale Hydrogeophysical Data Assimilation for Plume-Scale Subsurface Characterization

    NASA Astrophysics Data System (ADS)

    Wainwright, H. M.; Sassen, D. S.; Chen, J.; Hubbard, S. S.

    2011-12-01

    Predictions of subsurface contaminant plume evolution and natural attenuation capacity often fail due to the difficulty to tractably characterize heterogeneity of flow-and-transport properties at the plume-relevant scales. This study presents a stochastic-estimation framework for assimilating multiscale datasets and characterizing a plume-scale subsurface domain. We utilize the concept of reactive facies, which is based on the hypothesis that we can identify packages of sediments that have distinct distributions of properties influencing reactive transport, such as effective surface area, mineralogy and permeability. Because geophysical attributes are often sensitive to some of those properties, this concept allows us to take advantage of both geophysical and lithological datasets, to characterize the spatial distribution of reactive transport parameters. Previous research has illustrated that crosshole geophysical methods can be used to identify and spatially distribute reactive facies at the local scale. To map the spatial distribution of reactive facies at the plume-scale, we must (1) honor the large-scale trend without smoothing out the detail structure of facies, and (2) assimilate multi-source, multiscale datasets in a consistent manner, including wellbore data and crosshole and surface geophysical data. To tackle these challenges, we have developed a hierarchical Bayesian framework, which consists of three statistical sub-models: a data model, a process model, and a prior model. The data model - developed according to the stochastic feature of measurement errors - provides the linkage between the multiple geophysical datasets and the spatially distributed geophysical attributes through linear/nonlinear forward models. The process model describes the spatial distribution of reactive facies and geophysical attributes as spatial random processes controlled by geostatistical and petrophysical parameters. We use an indicator random field with a trend function for

  4. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching

    SciTech Connect

    Swain, Basudev Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo Lee, Chan Gi; Hong, Hyun Seon

    2015-04-15

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na{sub 2}CO{sub 3}, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na{sub 2}CO{sub 3}, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4 M HCl, 100 °C and pulp density of 20 g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. - Highlights: • Simplest process for treatment of GaN an LED industry waste developed. • The process developed recovers gallium from waste LED waste dust. • Thermal analysis and phase properties of GaN to Ga{sub 2}O{sub 3} and GaN to NaGaO{sub 2} revealed. • Solid-state chemistry involved in this process reported. • Quantitative leaching of the GaN was achieved.

  5. Structure, magnetic and magnetoresistance properties of Pr0.67Sr0.33MnO3 manganite oxide prepared by ball milling method

    NASA Astrophysics Data System (ADS)

    Chérif, W.; Ellouze, M.; Lehlooh, A.-F.; Elhalouani, F.; Mahmood, S. H.

    2012-07-01

    A sample of Pr0.67Sr0.33MnO3 nanoparticles was synthesized by the ball milling method. X-ray diffraction pattern of the sample showed orthorhombic system with Pnma space group. The average crystallite size of 110 nm was obtained by both Scanning Electron Microscopy and X-ray diffraction. Magnetic measurements showed para-to-ferromagnetic transition with a Curie temperature of TC=269 K. Electrical investigations showed that all our samples exhibit a semi-conducting behavior above TC and a metallic-like one at lower temperatures. The sample exhibited a large magnetoresistance of 30% at room temperature in an applied magnetic field of 2 T. The transport and the magnetic properties were interpreted in terms of the existence of magnetic polarons in the sample.

  6. Ultrathin SmCo5 nanoflakes with high-coercivity prepared by solid particle (NaCl) and surfactant co-assisted ball milling.

    PubMed

    Zuo, Wen-Liang; Zhao, Xin; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2016-01-01

    The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10-50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed. Temperature dependence of demagnetization curves indicate that the magnetization reversal may be controlled by both nucleation and pinning. The results of X-ray powder diffraction and magnetic measurement for aligned SmCo5 nanoflakes resin composite indicate that the nanoflakes have a high texture degree. The ultrathin thickness and high coercivity are beneficial for preparing the high performance soft/hard coupling magnets and nanocomposite magnets. PMID:27174410

  7. Ultrathin SmCo5 nanoflakes with high-coercivity prepared by solid particle (NaCl) and surfactant co-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhao, Xin; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2016-05-01

    The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10–50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed. Temperature dependence of demagnetization curves indicate that the magnetization reversal may be controlled by both nucleation and pinning. The results of X-ray powder diffraction and magnetic measurement for aligned SmCo5 nanoflakes resin composite indicate that the nanoflakes have a high texture degree. The ultrathin thickness and high coercivity are beneficial for preparing the high performance soft/hard coupling magnets and nanocomposite magnets.

  8. Effect of ball milling and thermal treatment on exchange bias and magnetocaloric properties of Ni48Mn39.5Sn10.5Al2 ribbons

    NASA Astrophysics Data System (ADS)

    Czaja, P.; Przewoźnik, J.; Fitta, M.; Bałanda, M.; Chrobak, A.; Kania, B.; Zackiewicz, P.; Wójcik, A.; Szlezynger, M.; Maziarz, W.

    2016-03-01

    The combined effect of ball milling and subsequent heat treatment on microstructure, magnetic, magnetocaloric and exchange bias properties of Ni48Mn39.5Sn10.5Al2 ribbons is reported. The annealing treatment results in the increase of the critical martensitic transformation temperature. The magnetic entropy change ΔSM of the order of 7.9 and -2.3 J kg K-1 for the annealed 50-32 μm powder fraction is determined. This is less than in the as melt spun ribbon but appears at a considerably higher temperature. At the same time EB is decreased due to annealing treatment. This decrease is attributed to the strengthened ferromagnetic exchange coupling due heat induced stress and structural relaxation.

  9. Structure-Property Correlation in Fe-Al2O3 In Situ Nanocomposite Synthesized by High-Energy Ball Milling and Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Udhayabanu, V.; Ravi, K. R.; Murty, B. S.

    2016-07-01

    In the present study, Fe-10 vol pct Al2O3 in situ nanocomposite has been derived by high-energy ball milling of Fe2O3-Fe-Al powder mixture followed by the consolidation using spark plasma sintering (SPS). The consolidated nanocomposite has bimodal-grained structure consisting of nanometer- and submicron-sized Fe grains along with nanometer-sized Al2O3, and Fe3O4 particles. The mechanical property analysis reveals that compressive yield strength of Fe-10 vol pct Al2O3 nanocomposite is 2100 MPa which is nearly two times higher than that of monolithic Fe processed by Mechanical Milling and SPS. The strengthening contributions obtained from matrix, grain size, and particles in the synthesized nanocomposite have been calculated theoretically, and are found to be matching well with the experimental strength levels.

  10. Ultrathin SmCo5 nanoflakes with high-coercivity prepared by solid particle (NaCl) and surfactant co-assisted ball milling

    PubMed Central

    Zuo, Wen-Liang; Zhao, Xin; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2016-01-01

    The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10–50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed. Temperature dependence of demagnetization curves indicate that the magnetization reversal may be controlled by both nucleation and pinning. The results of X-ray powder diffraction and magnetic measurement for aligned SmCo5 nanoflakes resin composite indicate that the nanoflakes have a high texture degree. The ultrathin thickness and high coercivity are beneficial for preparing the high performance soft/hard coupling magnets and nanocomposite magnets. PMID:27174410

  11. Morphology and magnetic properties of CeCo5 submicron flakes prepared by surfactant-assisted high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Zhang, J. J.; Gao, H. M.; Yan, Y.; Bai, X.; Su, F.; Wang, W. Q.; Du, X. B.

    2012-10-01

    CeCo5 permanent magnetic alloy has been processed by surfactant assisted high energy ball milling. Heptane and oleic acid were used as the solvent and surfactant, respectively. The amount of surfactant used was 50% by weight of the starting powder. The produced particles were deposited on a piece of copper (4 mm in length and width) under a magnetic field of 27 kOe applied along the copper surface and immobilized by ethyl α-cyanoacrylate. Scanning electron microscope pictures show that the particles are flakes, several μm in length and width and tens of nm in thickness. X-ray diffraction patterns and magnetic measurements prove that the flakes are crystalline with c-axes magnetic anisotropy. The easy magnetization axis is oriented perpendicular to the surface of the flake. A maximum coercivity of 3.3 kOe was obtained for the sample milled for 40 min.

  12. Layered-Layered-Spinel Cathode Materials Prepared by a High-Energy Ball-Milling Process for Lithium-ion Batteries.

    PubMed

    Kim, Soo; Noh, Jae-Kyo; Aykol, Muratahan; Lu, Zhi; Kim, Haesik; Choi, Wonchang; Kim, Chunjoong; Chung, Kyung Yoon; Wolverton, Chris; Cho, Byung-Won

    2016-01-13

    In this work, we report the electrochemical properties of 0.5Li2MnO3·0.25LiNi0.5Co0.2Mn0.3O2·0.25LiNi0.5Mn1.5O4 and 0.333Li2MnO3·0.333LiNi0.5Co0.2Mn0.3O2·0.333LiNi0.5Mn1.5O4 layered-layered-spinel (L*LS) cathode materials prepared by a high-energy ball-milling process. Our L*LS cathode materials can deliver a large and stable capacity of ∼200 mAh g(-1) at high voltages up to 4.9 V, and do not show the anomalous capacity increase upon cycling observed in previously reported three-component cathode materials synthesized with different routes. Furthermore, we have performed synchrotron-based in situ X-ray diffraction measurements and found that there are no significant structural distortions during charge/discharge runs. Lastly, we carry out (opt-type) van der Waals-corrected density functional theory (DFT) calculations to explain the enhanced cycle characteristics and reduced phase transformations in our ball-milled L*LS cathode materials. Our simple synthesis method brings a new perspective on the use of the high-power L*LS cathodes in practical devices. PMID:26645115

  13. Study of magnetic behavior in ball-milled nanocrystalline Fe-50 at.%Al alloy as a function of milling time

    NASA Astrophysics Data System (ADS)

    Rajan, S.; Shukla, R.; Kumar, A.; Vyas, A.; Brajpuriya, R.

    2015-04-01

    Ball milling technique has been extensively used to prepare different metastable states with nanocrystalline microstructures from intermetallic compounds. The present study was made on the identification of the changes in magnetic and electronic properties as a result of high-energy ball milling of Fe-50 at.%Al alloy samples. The phase formation and physical properties of the alloys were determined as a function of milling time by means of Mössbauer and X-ray photoelectron spectroscopy (XPS). The Mössbauer results show the formation of nanostructured body-centered cubic (BCC) FeAl alloy only after 5 h of mechanical milling and the same is also confirmed by Scanning electron microscope (SEM) and Transmission electron microscopy (TEM) studies. Mössbauer studies further confirm that there is magnetic behavior retention in the FeAl alloy samples even after 5 h of milling but magnetization decreases as the milling time increases. The reason for the same is due to the shocks and fracturing of the Al atoms embedded in the sites of Fe and as a result of which Fe-Fe nearest neighbors decreases. Secondly, with the increase in milling time, the particle size and the number density of equiatomic BCC Fe50Al50 grains decrease while the volume of grain boundary containing a solid solution of BCC FeAl and concentration of Al in a solid solution of BCC FeAl at the grain boundary increases as a result of which magnetization decreases. The shift in the binding energy of Fe2p and Al2p core level towards higher binding energy also supports the alloy formation after milling.

  14. Magnetic properties of Co1-xZnxFe2O4 spinel ferrite nanoparticles synthesized by starch-assisted sol-gel autocombustion method and its ball milling

    NASA Astrophysics Data System (ADS)

    Yadav, Raghvendra Singh; Havlica, Jaromir; Hnatko, Miroslav; Šajgalík, Pavol; Alexander, Cigáň; Palou, Martin; Bartoníčková, Eva; Boháč, Martin; Frajkorová, Františka; Masilko, Jiri; Zmrzlý, Martin; Kalina, Lukas; Hajdúchová, Miroslava; Enev, Vojtěch

    2015-03-01

    In this article, Co1-xZnxFe2O4 (x=0.0 and 0.5) spinel ferrite nanoparticles were achieved at 800 °C by starch-assisted sol-gel autocombustion method. To further reduce the particle size, these synthesized ferrite nanoparticles were ball-milled for 2 h. X-ray diffraction patterns demonstrated single phase formation of Co1-xZnxFe2O4 (x=0.0 and 0.5) spinel ferrite nanoparticles. FE-SEM analysis indicated the nanosized spherical particles formation with spherical morphology. The change in Raman modes and relative intensity were observed due to ball milling and consequently decrease of particle size and cationic redistribution. An X-ray Photoelectron Spectroscopy (XPS) result indicated that Co2+, Zn2+ and Fe3+ exist in octahedral and tetrahedral sites. The cationic redistribution of Zn2+ and consequently Fe3+ occurred between octahedral and tetrahedral sites after ball-milling. The change in saturation magnetization (Ms) and coercivity (Hc) with decrease of nanocrystalline size and distribution of cations in spinel ferrite were observed.

  15. A structural and Mössbauer study of Y3Fe5O12 nanoparticles prepared with high energy ball milling and subsequent sintering

    NASA Astrophysics Data System (ADS)

    Widatallah, H. M.; Johnson, C.; Al-Harthi, S. H.; Gismelseed, A. M.; Al-Rawas, A. D.; Stewart, S. J.; Elzain, M. E.; Al-Omari, I. A.; Yousif, A. A.

    2008-04-01

    The influence of ball milling and subsequent sintering of a 3:5 molar mixture of Y2O3 and α-Fe2O3 on the formation of nanocrystalline Y3Fe5O12 (YIG) particles is studied. Pre-milling the mixture for 100 h lowers the onset temperature at which the material forms to 900°C which is 200°C lower than that reported when a similar mixture of reactants was premilled for shorter times. A single-phased nanocrystalline Y3Fe5O12 phase develops as a sole product when the pre-milled mixture is heated at 1,000°C (12 h). This temperature is ~300-400°C lower than those used to prepare the material conventionally. The bulk and surface crystal structure of the nanoparticles is studied with X-ray diffraction, Mössbauer spectroscopy, Atomic Force Microscope (AFM) and X-ray photoelectron spectroscopy.

  16. Effects of zero-valent metals together with quartz sand on the mechanochemical destruction of dechlorane plus coground in a planetary ball mill.

    PubMed

    Wang, Haizhu; Huang, Jun; Zhang, Kunlun; Yu, Yunfei; Liu, Kai; Yu, Gang; Deng, Shubo; Wang, Bin

    2014-01-15

    Mechanochemical destruction by grinding with additives in high energy ball milling has been identified as a good alternative to traditional incineration for the disposal of wastes containing halogenated organic pollutants. Despite CaO normally used as an additive, recently Fe+SiO2 has been used to replace CaO for a faster destruction. In the present study, zero-valent metals (Al, Zn, besides Fe) together with SiO2 were investigated for their efficiencies of prompting the destruction of dechlorane plus (DP). Aluminum was found of be the best with a destruction percentage of nearly 99% for either syn- or anti-DP after 2.5h milling. In comparison, only 88/85% and 37/32% of syn-/anti-DP were destroyed when using zinc and iron after the same time, respectively. The detected water soluble chloride was lower than the stoichiometric amount containing in the original DP samples, due to the Si-Cl bond formed during the process. The potential fate of C and Cl present in DP is in the form of inorganic carbon, inorganic Cl and formation of Si-Cl bonds, respectively. The results suggested that Al+SiO2 is promising in the mechanochemical destruction of chlorinated organic pollutants like DP. PMID:24295775

  17. Magneto-optical properties of α-Fe2O3@ZnO nanocomposites prepared by the high energy ball-milling technique

    NASA Astrophysics Data System (ADS)

    Chaudhury, Chandana Roy; Roychowdhury, Anirban; Das, Anusree; Das, Dipankar

    2016-05-01

    Magnetic-fluorescent nanocomposites (NCs) with 10 wt% of α-Fe2O3 in ZnO have been prepared by the high energy ball-milling. The crystallite sizes of α-Fe2O3 and ZnO in the NCs are found to vary from 65 nm to 20 nm and 47 nm to 15 nm respectively as milling time is increased from 2 to 30 h. XRD analysis confirms presence of α-Fe2O3 and ZnO in pure form in all the NCs. UV-vis study of the NCs shows a continuous blue-shift of the absorption peak and a steady increase of band gap of ZnO with increasing milling duration that are assigned to decreasing particle size of ZnO in the NCs. Photoluminescence (PL) spectra of the NCs reveal three weak emission bands in the visible region at 421, 445 and 485 nm along with the strong near band edge emission at 391 nm. These weak emission bands are attributed to different defect - related energy levels e.g. Zn-vacancy, Zn interstitial and oxygen vacancy. Dc and ac magnetization measurements show presence of weakly interacting superparamagnetic (SPM) α-Fe2O3 particles in the NCs. 57Fe-Mössbauer study confirms presence of SPM hematite in the sample milled for 30 h. Positron annihilation lifetime measurements indicate presence of cation vacancies in ZnO nanostructures confirming results of PL studies.

  18. Nanoscale grains, high irreversibility field and large critical current density as a function of high-energy ball milling time in C-doped magnesium diboride

    NASA Astrophysics Data System (ADS)

    Senkowicz, B. J.; Mungall, R. J.; Zhu, Y.; Jiang, J.; Voyles, P. M.; Hellstrom, E. E.; Larbalestier, D. C.

    2008-03-01

    Magnesium diboride (MgB2) powder was mechanically alloyed by high-energy ball milling with C to a composition of Mg(B0.95C0.05)2 and then sintered at 1000 °C in a hot isostatic press. Milling times varied from 1 to 3000 min. Full C incorporation required only 30-60 min of milling. The grain size of sintered samples decreased with increased milling time to <30 nm for 20-50 h of milling. Milling had a weak detrimental effect on the connectivity. A strong irreversibility field (H*) increase (from 13.3 to 17.2 T at 4.2 K) due to increased milling time was observed and correlated linearly with inverse grain size (1/d). As a result, the high-field Jc benefited greatly from lengthy powder milling. Jc (8 T, 4.2 K) peaked at>80 000 A cm-2 with 1200 min of milling compared with only ~26 000 A cm-2 for 60 min of milling. This non-compositional performance increase is attributed to grain refinement of the unsintered powder by milling, and to the probable suppression of grain growth by milling-induced MgO nanodispersions.

  19. Structural, spectral and DFT studies of N-ethyl-2-(4-(phenylamino)-4-thioxobutan-2-ylidene)hydrazinecarbothioamide complexes synthesized by ball milling

    NASA Astrophysics Data System (ADS)

    Zaky, Rania; Fekri, Ahmed

    2015-01-01

    Thiosemicarbazone complexes of Ni(II), Co(II), Cu(II) and VO(II) with the N-ethyl-2-(4-(phenylamino)-4-thioxobutan-2-ylidene)hydrazinecarbothioamide (H2L) containing hard-soft NS donor sites were prepared by two different methods, the first was by ball milling as a green strategy and the second was by refluxing as the traditional method. The isolated solid compounds were elucidated by elemental analysis, spectroscopy (1H NMR, IR, UV-visible, ESR, MS spectra), and physical measurements (magnetic susceptibility and molar conductance). IR spectra suggested that the H2L behaved as a neutral or mononegative bidentate ligand depending on the method used. The room temperature solid state ESR spectra of the Cu(II) complex showed dx2-y2 as a ground state, suggesting tetragonally distorted octahedral geometry around Cu(II) center. The DFT was evaluated to confirm the geometry of the investigated compounds. Also, the antimicrobial activity of all compounds was studied using a wide spectrum of bacterial and fungal strains.

  20. Influence of ball milling and annealing conditions on the properties of L10 FePt nanoparticles fabricated by a new green chemical synthesis method

    NASA Astrophysics Data System (ADS)

    Hu, X. C.; Capobianchi, A.; Gallagher, R.; Hadjipanayis, G. C.

    2014-05-01

    In this work, a new green chemical strategy for the synthesis of L10 FePt alloy nanoparticles is reported. The precursor is a polycrystalline molecular complex (Fe(H2O)6PtCl6), in which Fe and Pt atoms are arranged on alternating planes and milled with NaCl to form nanocrystals. Then the mixture was annealed under reducing atmosphere (5% H2 and 95% Ar) at temperatures varying from 350 °C to 500 °C for 2 h with a heating rate of 5 °C/min. After the reduction, the mixture was washed with water to remove the NaCl and L10 FePt nanoparticles were obtained. The X-Ray Diffraction pattern showed the presence of the characteristic peaks of the fct phase of FePt nanoparticles. Influence of precursor/NaCl ratio and ball milling time on particle size was investigated. Transmission electron microscopy images revealed that smaller precursor/NaCl ratio (10 mg/20 g) and longer milling time (15 h) lead to smaller particle size and narrower size distribution. Milling time does not influence the coercivity much but the decrease of the amount of precursor leads to a decrease of coercivity from 10.8 kOe to 4.8 kOe.

  1. Magnetic properties and coercivity mechanism of Sm1-xPrxCo5 (x=0-0.6) nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Xu, M. L.; Yue, M.; Wu, Q.; Li, Y. Q.; Lu, Q. M.

    2016-05-01

    Sm1-xPrxCo5 (x=0-0.6) nanoflakes with CaCu5 structure were successfully prepared by surfactant-assisted high-energy ball milling (SAHEBM). The crystal structure and magnetic properties of Sm1-xPrxCo5 (x=0-0.6) nanoflakes were studied by X-ray diffraction and vibrating sample magnetometer. Effects of Pr addition on the structure, magnetic properties and coercivity mechanism of Sm1-xPrxCo5 nanoflakes were systematically investigated. XRD results show that all the nanoflakes have a hexagonal CaCu5-type (Sm, Pr)1Co5 main phase and the (Sm, Pr)2Co7 impurity phase, and all of the samples exhibit a strong (00l) texture after magnetic alignment. As the Pr content increases, remanence firstly increases, then slightly reduced, while anisotropy field (HA) and Hci of decrease monotonically. Maximum energy product [(BH)max] of the flakes increases first, peaks at 24.4 MGOe with Pr content of x = 0.4, then drops again. Magnetization behavior analysis indicate that the coercivity mechanism is mainly controlled by inhomogeneous domain wall pinning, and the pinning strength weakens with the increased Pr content, suggesting the great influence of HA on the coercivity of flakes.

  2. Facile solid state ball milling as a green strategy to prepare 2-(2,4-dichlorophenoxy)-N‧-(2-hydroxybenzylidene)acetohydrazide complexes

    NASA Astrophysics Data System (ADS)

    Fekri, Ahmed; Zaky, Rania

    2014-11-01

    2-(2,4-Dichlorophenoxy)-N‧-(2-hydroxybenzylidene)acetohydrazide (H2L) complexes were prepared by ball milling involving the reaction of ligand with Ni(II), Co(II), Cu(II) and VO(II) salts (mechanochemical syntheses). The compounds were elucidated by elemental analysis, spectroscopy (1H NMR, IR, UV-visible, MS spectra), and physical measurements (magnetic susceptibility and molar conductance). IR spectra suggested that the H2L behaved as a monodentate and/or bidentate ligand coordinating via azomethine nitrogen and/or deprotonated enolized carbonyl oxygen. The electronic spectra of the complexes and their magnetic moments provided information about geometries. The antimicrobial activities of the ligand and its complexes were studied against gram positive bacteria; Staphylococcus aureus, gram-negative bacteria; Escherichia coli and pathogenic fungi; Candida albicans by using minimum inhibition concentrations method (MIC). Also, the antioxidant (ABTS-derived free radical method) and cytotoxic (in vitro Ehrlich Ascites) activities of the isolated compounds were evaluated.

  3. Binding of carbon coated nano-silicon in graphene sheets by wet ball-milling and pyrolysis as high performance anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Hu, Renzong; Zhang, Miao; Liu, Jiangwen; Zhu, Min

    2016-06-01

    A novel approach has been developed to prepare silicon@carbon/graphene sheets (Si@C/G) composite with a unique structure, in which carbon coated Si nanoparticles are uniformly dispersed in a matrix of graphene sheets, to enhance the cycleability and electronic conductivity of Si-based anodes for Li-ion batteries. In this study, Si nanoparticles and expanded graphite (EG) are treated by combining high-energy wet ball-milling in sucrose solution with subsequent pyrolysis treatment to produce this Si@C/G composite. To achieve better overall electrochemical performance, the carbon content of the composites is also studied systematically. The as-designed Si30@C40/G30 (Si:C:G = 30:40:30, by weight) composite exhibits a high Li-storage capacity of 1259 mAh g-1 at a current density of 0.2 A g-1 in the first cycle. Further, a stable cycleability with 99.1/88.2% capacity retention from initial reversible charge capacity can be achieved over 100/300 cycles, showing great promise for batteries applications. This good electrochemical performance can be attributed to the uniform coating and binding effect of pyrolytic carbon as well as the network of graphene sheets, which increase the electronic conductivity and Li+ diffusion in the composite, and effectively accommodated the volume change of Si nanoparticles during the Li+ alloying and dealloying processes.

  4. Magnetization reversal behavior of SmCo6.6Nb0.4 nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Li, Y. Q.; Yue, M.; Wu, Q.; Liu, W. Q.; Zhang, D. T.; Lu, Q. M.

    2016-05-01

    In this paper, the recoil loops of SmCo6.6Nb0.4 nanoflakes prepared by the surfactant-assisted high energy ball milling (SA-HEBM) were systematically studied. The recoil loop openness was observed in both the aligned and non-aligned samples. Reversible and irreversible portions of the demagnetization process derived from the recoil loop were also investigated. For both the aligned and non-aligned samples, reversible portion (▵mrev) is too small to determine the coercivity. Irreversible portion (▵mirrev) shows similar tendency, i.e. increasing slowly at low reverse field and then growing up rapidly after a critical field (nucleation field Hno). The demagnetization process can be described as following: the reversible demagnetization is dominant when the applied reverse field is lower than 8 kOe, under which the irreversible nucleation also occurs. The reverse domain walls are pinned by the grain boundaries until the reverse field is larger than 8 kOe. With increasing field, the pinning effects are weakened and the rapid reversible demagnetization starts. Finally, the demagnetization process is accomplished. The values of ΔM in the Henkel plots are totally opposite for the aligned and non-aligned SmCo6.6Nb0.4 nanoflakes.

  5. Influence of ball milling and annealing conditions on the properties of L1{sub 0} FePt nanoparticles fabricated by a new green chemical synthesis method

    SciTech Connect

    Hu, X. C.; Capobianchi, A.; Gallagher, R.; Hadjipanayis, G. C.

    2014-05-07

    In this work, a new green chemical strategy for the synthesis of L1{sub 0} FePt alloy nanoparticles is reported. The precursor is a polycrystalline molecular complex (Fe(H{sub 2}O){sub 6}PtCl{sub 6}), in which Fe and Pt atoms are arranged on alternating planes and milled with NaCl to form nanocrystals. Then the mixture was annealed under reducing atmosphere (5% H{sub 2} and 95% Ar) at temperatures varying from 350 °C to 500 °C for 2 h with a heating rate of 5 °C/min. After the reduction, the mixture was washed with water to remove the NaCl and L1{sub 0} FePt nanoparticles were obtained. The X-Ray Diffraction pattern showed the presence of the characteristic peaks of the fct phase of FePt nanoparticles. Influence of precursor/NaCl ratio and ball milling time on particle size was investigated. Transmission electron microscopy images revealed that smaller precursor/NaCl ratio (10 mg/20 g) and longer milling time (15 h) lead to smaller particle size and narrower size distribution. Milling time does not influence the coercivity much but the decrease of the amount of precursor leads to a decrease of coercivity from 10.8 kOe to 4.8 kOe.

  6. Novel fabrication of solid-state NaBH 4/Ru-based catalyst composites for hydrogen evolution using a high-energy ball-milling process

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Hong; Chen, Bing-Hung; Hsueh, Chan-Li; Ku, Jie-Ren; Tsau, Fanghei

    Solid-state NaBH 4/Ru-based catalyst composites have been fabricated for hydrogen generation through a high-energy ball-milling process, providing uniform dispersion of resin-supported Ru 3+ catalysts among pulverized NaBH 4 (SBH) particles, so as to increase the contacts of SBH with active catalytic sites. Consequently, the gravimetric hydrogen storage capacity as high as 7.3 wt% could be achieved by utilizing water as a limiting reagent to overcome the issue of deactivated catalysts whose active sites are often blocked by precipitates caused by limited NaBO 2 solubility occurring in conventional aqueous SBH systems for hydrogen productions. Products of hydrolyzed SBH that greatly influence the gravimetric H 2 storage capacity are found to be most likely NaBO 2·2H 2O and NaBO 2·4H 2O from SBH/H 2O reacting systems with initial weight ratios, SBH/H 2O = 1/2 and 1/10, respectively, according to the TGA and XRD analyses.

  7. Enhanced coercivity and remanence of PrCo5 nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhao, Xin; Xiong, Jie-Fu; Shang, Rong-Xiang; Zhang, Ming; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-07-01

    PrCo5 nanoflakes with strong texture and high coercivity of 8.15 kOe were prepared by surfactant-assisted ball milling with heat-treated starting powder. The thickness and length of the as-milled nanoflakes are mainly in the ranges of 50-100 nm and 0.5-3 μm, respectively. The x-ray diffraction patterns demonstrate that the heat treatment can increase the single phase and crystallinity of the PrCo5 compound, and combined with the demagnetization curves, indicate that the single phase and crystallinity are important for preparing high-coercivity and strong-textured rare earth permanent magnetic nanoflakes. In addition, the coercivity mechanism of the as-milled PrCo5 nanoflakes is studied by the angle dependence of coercivity for an aligned sample and the field dependence of coercivity, isothermal (IRM) and dc demagnetizing (DCD) remanence curves for an unaligned sample. The results indicate that the coercivity is dominated by co-existing mechanisms of pinning and nucleation. Furthermore, exchange coupling and dipolar coupling also co-exist in the sample. Project supported by the National Basic Research Program of China (Grant No. 2014CB643702), the National Natural Science Foundation of China (Grant No. 51401235), and Beijing Natural Science Foundation, China (Grant No. 2152034).

  8. The grinding behavior of ground copper powder for Cu/CNT nanocomposite fabrication by using the dry grinding process with a high-speed planetary ball mill

    NASA Astrophysics Data System (ADS)

    Choi, Heekyu; Bor, Amgalan; Sakuragi, Shiori; Lee, Jehyun; Lim, Hyung-Tae

    2016-01-01

    The behavior of ground copper powder for copper-carbon nanotube (copper-CNT) nanocomposite fabrication during high-speed planetary ball milling was investigated because the study of the behavior characteristics of copper powder has recently gained scientific interest. Also, studies of Cu/CNT composites have widely been done due to their useful applications to enhanced, advanced nano materials and components, which would significantly improve the properties of new mechatronics-integrated materials and components. This study varied experimental conditions such as the rotation speed and the grinding time with and without CNTs, and the particle size distribution, median diameter, crystal structure and size, and particle morphology were monitored for a given grinding time. We observed that pure copper powders agglomerated and that the morphology changed with changing rotation speed. The particle agglomerations were observed with maximum experiment conditions (700 rpm, 60 min) in this study of the grinding process for mechanical alloys in the case of pure copper powders because the grinding behavior of Cu/CNT agglomerations was affected by the addition of CNTs. Indeed, the powder morphology and the crystal size of the composite powder could be changed by increasing the grinding time and the rotation speed.

  9. Covalent modification of glassy carbon spheres through ball milling under solvent free conditions: A novel electrochemical interface for mercury(II) quantification.

    PubMed

    Kempegowda, Raghu G; Malingappa, Pandurangappa

    2014-08-01

    A simple and green chemistry protocol has been proposed based on the covalent anchoring of benzamide molecule on glassy carbon spheres through ball milling under solvent free condition. The modification proceeds through the formation of an amide bond between carboxylic group of glassy carbon spheres and the amino group of modifier molecule. The formation of covalent bond was ascertained using X-ray photoelectron spectroscopy. Scanning electron microscopy was used to study the surface morphology of milled glassy carbon spheres. The aqueous colloidal solution of modified glassy carbon spheres was used in the preparation of thin film electrodes and subsequently used as a novel electrochemical interface in the quantification of mercury at trace level using a differential pulse anodic stripping voltammetric technique. The modified electrode showed good sensitivity and selectivity towards mercury with a detection limit of 1nM with least interference from most of the ions. The analytical utility of the proposed electrode has been validated by determining the mercury levels in number of sample matrices. PMID:24881534

  10. M{umlt o}ssbauer investigation of intermixing during ball milling of Fe{sub 0.3}Cr{sub 0.7} and Fe{sub 0.5}W{sub 0.5} powder mixtures

    SciTech Connect

    Le Caeer, G.; Delcroix, P.; Shen, T.D.; Malaman, B.

    1996-11-01

    Intermixing of Fe and T (T=Cr,W) during ball milling of elemental powder mixtures Fe{sub 1{minus}x}T{sub x}, with x=0.70 for T=Cr and x=0.50 for T=W, has been followed by {sup 57}Fe M{umlt o}ssbauer spectroscopy at room temperature (RT) and by magnetization measurements for T=W. The chemical compositions have been chosen to yield final alloys or compounds which are nonmagnetic at RT to better follow the evolution of magnetic phases with milling times. For a long period of milling time t{sub m} before reaching the final stationary state, the hyperfine magnetic field distributions remain stationary in shape for both T=Cr and T=W. Only the relative weight of the magnetic contribution decreases with t{sub m}. For T=W, the average moment of magnetic Fe atoms is further shown to remain constant with t{sub m}. Stationary hyperfine field distribution shapes are found to be similar not only for {ital T}=Cr and W but also for T=Si (x=0.50) while published spectra suggest to add T=Al, Ti, V, Ta, Re to the latter nonexhaustive list. The stationary shape is characterized by a narrow peak located at a field close to the field of alpha iron at RT (330 kG) and by a broad, almost featureless, band from 50-100 kG to 300-320 kG. The broad band represents about 2/3 of the normalized field distribution. We deduce that the interpretation which consists in attributing the x-ray diffraction peaks of Fe-based bcc solid solutions to a single Fe-rich homogeneous solid solution must be done with care for intermediate milling times. We cannot infer from such hyperfine measurements a detailed description of the regions of the powders which are responsible for such magnetic features. We argue however that irregular interfaces between nanometer-sized Fe-rich zones and {ital T}-rich zones may play a role to explain the observed shape of the hyperfine field distributions.

  11. Morphological, Thermal, and Magnetic Analysis of Ball-Milled γ-Fe2O3 and Fe3O4 Nanoparticles for Biomedical Application

    NASA Astrophysics Data System (ADS)

    Burnham, Philip; Papaefthymiou, Georgia C.; Viescas, Arthur; Li, Calvin; Dollahon, Norman

    2013-03-01

    Superparamagnetic iron oxide nanoparticles are promising agents for hyperthermia cancer treatment, because, when exposed to an alternating magnetic field, they impart heat to surrounding tissue. A comparison of γ-Fe2O3 and Fe3O4 nanoparticles for such application is presented. The particles were obtained via surfactant-assisted high energy ball-milling in a hexane/oleic acid carrier-fluid environment. Particles with diameters of 5 to 16 nm were prepared with mass ratios (oleic acid):(γ-Fe2O3) of 0:1, 1:5, 1:10 and 1:20, with milling times of 3, 6, 9, and 12 hours. TEM micrographs revealed spherical morphology and the effect of oleic acid shells. Optimal size distributions were obtained for high oleic acid contents. At room temperature, a reduced internal magnetic field ~480 kOe) was recorded via Mössbauer spectroscopy compared to bulk γ-Fe2O3 ~500 kOe), due to magnetic relaxation; Fe3O4 particles produced similar results. For the γ-Fe2O3 and Fe3O4 nanoparticles with 20% oleic acid by mass, comparative ZFC/FC magnetization (Happ = 200 Oe in temperature range from 2 to 400 K) and hysteresis loops (T = 2 K and 300 K up to Happ = 6 kOe) were obtained. Thermal transport characteristics were verified by Specific Absorption Rate (SAR) measurements using an AC magnetic field (f = 282 kHz). Differences and similarities in behavior will be discussed.

  12. Cathode performance of LiMnPO 4/C nanocomposites prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment

    NASA Astrophysics Data System (ADS)

    Doan, The Nam Long; Taniguchi, Izumi

    LiMnPO 4/C nanocomposites could be prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment in the range of spray pyrolysis temperature from 200 to 500 °C. The ordered LiMnPO 4 olivine structure without any impurity phase could be identified by X-ray diffraction analysis for all samples. It could be also confirmed from scanning electron microscopy and transmission electron microscopy observations that the final samples were the LiMnPO 4/C nanocomposites with approximately 100 nm in primary particles size. The LiMnPO 4/C nanocomposite samples were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1 M LiPF 6 in EC:DMC = 1:1|LiMnPO 4/C at various charge/discharge rates in three charge modes. As a result, the final sample which was synthesized at 300 °C by spray pyrolysis showed the best electrochemical performance due to the largest specific surface area, the smallest primary particle size and a well distribution of carbon. At galvanostatic charge/discharge rates of 0.05 C, the cell delivered first discharge capacities of 123 and 165 mAh g -1 in correspondence to charge cutoff voltages of 4.4 and 5.0 V, respectively. Furthermore, in a constant current-constant voltage charge mode at 4.4 V, the cells also exhibited initial discharge capacities of 147 mAh g -1 at 0.05 C, 145 mAh g -1 at 0.1 C, 123 mAh g -1 at 1 C and 65 mAh g -1 at 10 C. Moreover, the cells showed fair good cycleability over 100 cycles.

  13. EXAFS Studies and Microwave Magnetic Properties of FeGaB Thin Films and FeCuZr Ball-Milled Alloys

    NASA Astrophysics Data System (ADS)

    Gao, Jinsheng

    X-ray absorption fine structure (XAFS) is a spectroscopic technique which can investigate the physical and chemical structure of materials at the atomic scale. X-rays are applied in this technique to be near and above the binding energy of a particular core electronic level of a particular atomic species. Over the last decades, XAFS has emerged as a highly informative probe of the local structure around selected atomic species in solids, liquids, and molecular gases. It offers both element specificity and local structure sensitivity. Foremost among its strengths are its ability to probe the local atomic environments of different elements in the sample by selecting the corresponding incident X-ray energy. In the first part of this thesis, FeGaB alloys, which are of value as soft magnetic materials having relatively large magnetostriction coefficient, were fabricated in which varying amounts of boron were added to the host FeGa alloy to investigate its impact upon local atomic structure and magnetic and microwave properties. The impact of B upon the local atomic structure in FeGaB films were investigated by extended X-ray absorption fine structure (EXAFS) analysis. EXAFS fitting results revealed a contraction of lattice parameters with the introduction of B. The Debye-Waller factor determined from EXAFS fitting gradually increases as a function of boron addition and abruptly increases during the structural evolution from crystalline to amorphous. Upon the onset of this transition the static and microwave magnetic properties became exceptionally softer, with values of coercivity and ferromagnetic linewidth reducing dramatically. In the second part of this thesis, metastable alloys of the composition FeCuZr were synthesized by high energy ball milling and measured by EXAFS . The fitting results demonstrate that nanocrystalline or amorphous alloys have been obtained depending on the Zr content.

  14. CHARACTERIZING COUPLED CHARGE TRANSPORT WITH MULTISCALE MOLECULAR DYNAMICS

    SciTech Connect

    Swanson, Jessica

    2011-08-31

    This is the final progress report for Award DE-SC0004920, entitled 'Characterizing coupled charge transport with multi scale molecular dynamics'. The technical abstract will be provided in the uploaded report.

  15. Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

    NASA Astrophysics Data System (ADS)

    Nosbi, Norlin; Akil, Hazizan Md

    2015-06-01

    This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5-15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time.

  16. Multi-scale Characterization of Cellulose TEMPO-Nanofiber Suspension

    NASA Astrophysics Data System (ADS)

    Mao, Yimin; Liu, Kai; Hsiao, Benjamin

    Cellulose nanofiber (CNF) suspensions were characterized at multiple length scales. CNF suspension was prepared by applying 2,2,6,6-tetramethyl-1- piperidinyloxy (TEMPO) oxidation method to dry wood pulp. TEMPO method was able to produce fine fibers with a cross section dimension being in the order of magnitude of several nanometers, and length being several hundred nanometers. The surface was negatively charged. Charge density was characterized by Zeta-potential measurement. Both small-angle X-ray (SAXS) and small-angle neutron (SANS) methods were employed to examine fiber dimensions in solution. Data fitting indicated that newly-developed ribbon model was able to capture the essence of CNF's geometry, which is also computationally economic. The rectangular-shaped cross section was consistent to cellulose's crystal structure; and was able to provide insights into how cellulose crystals were biologically synthesized and packed in nature. Multi-angle dynamic light scattering (DLS) was used to study CNF's diffusion properties. A strong scattering-angle dependence of auto-correlation function was observed. The characterization is useful to understanding suspension quality of CNF, and can provide guideline for follow-up research aimed for a variety of applications.

  17. [Formula: see text]-mediated amination/cyclization of ketones with 2-aminopyridines under high-speed ball milling: solvent- and metal-free synthesis of 2,3-substituted imidazo[1,2-a]pyridines and zolimidine.

    PubMed

    Wang, Fang-Jian; Xu, Hui; Xin, Ming; Zhang, Ze

    2016-08-01

    Under solvent-free high-speed ball milling, an I[Formula: see text]-promoted condensation/cyclization of easily available methyl ketones or 1,3-dicarbonyl compounds with 2-aminopyridines has been developed, which allows the quick assembly of 2,3-substituted imidazo[1,2-a]pyridines (IPs) with broad molecular diversity, including the antiulcer drug zolimidine. The advantages of high yields, good functional group compatibility, short reaction time (within 90 min), free use of heating, solvent and metal, employment of cheap starting materials, and simple work-up procedure make this protocol a very efficient alternative to traditional synthesis of IPs. PMID:26975201

  18. Multiscale Characterization of Geological Properties of Oil Shale

    NASA Astrophysics Data System (ADS)

    Mehmani, Y.; Burnham, A. K.; Vanden Berg, M. D.; Tchelepi, H.

    2015-12-01

    Detailed characterization of geologic properties of oil shale is important for predictive modeling of geomechanics as well as heat and mass transfer in these geomaterials. Specifically, quantitative knowledge of the spatial distribution of thermal, hydraulic, and mechanical properties is requisite. The primary parameter upon which these properties strongly depend is kerogen content. We have developed a simple but accurate method for quantifying the spatial distribution of kerogen content, spanning scales from a few microns to a hundred feet. Our approach is based on analyzing raw optical images. Promising results regarding the viability of this approach, based on comparison with lab measurements, are presented for the well-known Mahogany Zone of the Green River Formation, Utah. A combination of Scanning Electron Microscopy (SEM) and appropriately chosen mixing rules allows for the quantification of thermal, hydraulic, and mechanical properties with micron-scale resolution. Numerical upscaling can subsequently produce averaged properties at the scale of individual grid blocks in field-scale simulators.

  19. Solution-state 2D NMR of ball-milled plant cell wall gels in DMSO-d6/pyridine-d5†

    PubMed Central

    Ralph, John

    2014-01-01

    NMR fingerprinting of the components of finely divided plant cell walls swelled in DMSO has been recently described. Cell wall gels, produced directly in the NMR tube with perdeutero-dimethylsulfoxide, allowed the acquisition of well resolved/dispersed 2D 13C–1H correlated solution-state NMR spectra of the entire array of wall polymers, without the need for component fractionation. That is, without actual solubilization, and without apparent structural modification beyond that inflicted by the ball milling and ultrasonication steps, satisfactorily interpretable spectra can be acquired that reveal compositional and structural details regarding the polysaccharide and lignin components in the wall. Here, the profiling method has been improved by using a mixture of perdeuterated DMSO and pyridine (4:1, v/v). Adding pyridine provided not only easier sample handling because of the better mobility compared to the DMSO-d6-only system but also considerably elevated intensities and improved resolution of the NMR spectra due to the enhanced swelling of the cell walls. This modification therefore provides a more rapid method for comparative structural evaluation of plant cell walls than is currently available. We examined loblolly pine (Pinus taeda, a gymnosperm), aspen (Populus tremuloides, an angiosperm), kenaf (Hibiscus cannabinus, an herbaceous plant), and corn (Zea mays L., a grass, i.e., from the Poaceae family). In principle, lignin composition (notably, the syringyl : guaiacyl : p-hydroxyphenyl ratio) can be quantified without the need for lignin isolation. Correlations for p-coumarate units in the corn sample are readily seen, and a variety of the ferulate correlations are also well resolved; ferulates are important components responsible for cell wall cross-linking in grasses. Polysaccharide anomeric correlations were tentatively assigned for each plant sample based on standard samples and various literature data. With the new potential for chemometric analysis

  20. Multiscale seismic characterization of marine sediments by using a wavelet-based approach

    NASA Astrophysics Data System (ADS)

    Ker, Stephan; Le Gonidec, Yves; Gibert, Dominique

    2015-04-01

    We propose a wavelet-based method to characterize acoustic impedance discontinuities from a multiscale analysis of reflected seismic waves. This method is developed in the framework of the wavelet response (WR) where dilated wavelets are used to sound a complex seismic reflector defined by a multiscale impedance structure. In the context of seismic imaging, we use the WR as a multiscale seismic attributes, in particular ridge functions which contain most of the information that quantifies the complex geometry of the reflector. We extend this approach by considering its application to analyse seismic data acquired with broadband but frequency limited source signals. The band-pass filter related to such actual sources distort the WR: in order to remove these effects, we develop an original processing based on fractional derivatives of Lévy alpha-stable distributions in the formalism of the continuous wavelet transform (CWT). We demonstrate that the CWT of a seismic trace involving such a finite frequency bandwidth can be made equivalent to the CWT of the impulse response of the subsurface and is defined for a reduced range of dilations, controlled by the seismic source signal. In this dilation range, the multiscale seismic attributes are corrected from distortions and we can thus merge multiresolution seismic sources to increase the frequency range of the mutliscale analysis. As a first demonstration, we perform the source-correction with the high and very high resolution seismic sources of the SYSIF deep-towed seismic device and we show that both can now be perfectly merged into an equivalent seismic source with an improved frequency bandwidth (220-2200 Hz). Such multiresolution seismic data fusion allows reconstructing the acoustic impedance of the subseabed based on the inverse wavelet transform properties extended to the source-corrected WR. We illustrate the potential of this approach with deep-water seismic data acquired during the ERIG3D cruise and we compare

  1. Synthesis and characterization of Al-Zn/Al2O3 nano-powder composites.

    PubMed

    Durai, T G; Das, Karabi; Das, Siddhartha

    2007-06-01

    Composites consisting of Al-Zn/Al2O3 have been synthesized using high energy mechanical milling. High energy ball milling increases the sintering rate of the composite powder due to increased diffusion rate. Owing to the finer microstructure, the hardness of the sintered composite produced by using the mechanically milled nanocomposite powder is significantly higher than that of the sintered composite produced by using the as-mixed powder. The mean crystallite size of the matrix has been determined to be 27 nm by Scherrer equation using X-ray diffraction data. The powders have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and differential thermal analysis (DTA). The effect of high-energy ball milling and subsequent annealing on a mixture of Al and ZnO has also been investigated. DTA result show that the reaction temperature of Al-ZnO decreases with the increase in the ball milling time. PMID:17654976

  2. Towards Characterization, Modeling, and Uncertainty Quantification in Multi-scale Mechanics of Oragnic-rich Shales

    NASA Astrophysics Data System (ADS)

    Abedi, S.; Mashhadian, M.; Noshadravan, A.

    2015-12-01

    Increasing the efficiency and sustainability in operation of hydrocarbon recovery from organic-rich shales requires a fundamental understanding of chemomechanical properties of organic-rich shales. This understanding is manifested in form of physics-bases predictive models capable of capturing highly heterogeneous and multi-scale structure of organic-rich shale materials. In this work we present a framework of experimental characterization, micromechanical modeling, and uncertainty quantification that spans from nanoscale to macroscale. Application of experiments such as coupled grid nano-indentation and energy dispersive x-ray spectroscopy and micromechanical modeling attributing the role of organic maturity to the texture of the material, allow us to identify unique clay mechanical properties among different samples that are independent of maturity of shale formations and total organic content. The results can then be used to inform the physically-based multiscale model for organic rich shales consisting of three levels that spans from the scale of elementary building blocks (e.g. clay minerals in clay-dominated formations) of organic rich shales to the scale of the macroscopic inorganic/organic hard/soft inclusion composite. Although this approach is powerful in capturing the effective properties of organic-rich shale in an average sense, it does not account for the uncertainty in compositional and mechanical model parameters. Thus, we take this model one step forward by systematically incorporating the main sources of uncertainty in modeling multiscale behavior of organic-rich shales. In particular we account for the uncertainty in main model parameters at different scales such as porosity, elastic properties and mineralogy mass percent. To that end, we use Maximum Entropy Principle and random matrix theory to construct probabilistic descriptions of model inputs based on available information. The Monte Carlo simulation is then carried out to propagate the

  3. Effects of Processing Parameters on the Synthesis of (K0.5Na0.5)NbO3 Nanopowders by Reactive High-Energy Ball Milling Method

    PubMed Central

    Duc Van, Nguyen

    2014-01-01

    The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C. PMID:24592146

  4. Characterization of mechanical nanocrystallization process of amorphous Fe{endash}Mo{endash}Si{endash}B alloy by transmission Moessbauer spectroscopy

    SciTech Connect

    Liu, X.D.; Lu, K.; Umemoto, M.

    1997-03-01

    The nanocrystallization process of the amorphous Fe{endash}Mo{endash}Si{endash}B alloy under ball milling is characterization by means of transmission M{umlt o}ssbauer spectroscopy in the present paper. It was found that a single {alpha}-Fe phase with the bcc structure is formed under ball-milling the amorphous Fe{endash}Mo{endash}Si{endash}B alloy. A significant increase in the relative area of the subspectra of 8 Fenn and 7 Fenn and a remarkable decrease in isomer shift and half linewidth of the subspectra of various Fe configurations, especially in the case of 6 Fenn, were observed during the ball milling process. The diffusion of metalloid atoms from the bcc {alpha}-Fe phase to the remaining amorphous phase and {alpha}-Fe/{alpha}-Fe grain boundaries is suggested to occur during the mechanical crystallization of the current amorphous alloy based on the above TMES investigations. {copyright} {ital 1997 Materials Research Society.}

  5. Multi-scale mechanical characterization of scaffolds for heart valve tissue engineering.

    PubMed

    Argento, G; Simonet, M; Oomens, C W J; Baaijens, F P T

    2012-11-15

    Electrospinning is a promising technology to produce scaffolds for cardiovascular tissue engineering. Each electrospun scaffold is characterized by a complex micro-scale structure that is responsible for its macroscopic mechanical behavior. In this study, we focus on the development and the validation of a computational micro-scale model that takes into account the structural features of the electrospun material, and is suitable for studying the multi-scale scaffold mechanics. We show that the computational tool developed is able to describe and predict the mechanical behavior of electrospun scaffolds characterized by different microstructures. Moreover, we explore the global mechanical properties of valve-shaped scaffolds with different microstructural features, and compare the deformation of these scaffolds when submitted to diastolic pressures with a tissue engineered and a native valve. It is shown that a pronounced degree of anisotropy is necessary to reproduce the deformation patterns observed in the native heart valve. PMID:22999107

  6. Direct three-dimensional characterization and multiscale visualization of wheat straw deconstruction by white rot fungus.

    PubMed

    Liu, Li; Qian, Chen; Jiang, Lei; Yu, Han-Qing

    2014-08-19

    Microbial degradation of lignocellulose for resource and energy recovery has received increasing interest. Despite its obvious importance, the mechanism behind the biodegradation, especially the changes of morphological structure and surface characteristics, has not been fully understood. Here, we used three-dimensional (3D) characterization and multiscale visualization methods, in combination with chemical compositional analyses, to elucidate the degradation process of wheat straw by a white rot fungus, Phanerochaete chrysosporium. It was found that the fungal attack initiated from stomata. Lignin of the straw decayed in both size and quantity, and heterogeneity in the biodegradation was observed. After treatment with the fungus, the straw surface turned from hydrophobic to hydrophilic, and the adhesion of the straw surface increased in the fungal degradation. The morphology of the straw outer layer became heterogeneous and loose with the formation of many holes with various sizes. The wasp-tunnels-like structure of the collenchyma and parenchyma of the straw as well as the fungal hyphae interspersed inside the straw structure were clearly visualized in the 3D reconstruction structure. This work offers a new insight into the mechanism of lignocellulose biodegradation and demonstrates that multiscale visualization methods could be a useful tool to explore such complex processes. PMID:25072830

  7. Multiscale characterization method for line edge roughness based on redundant second generation wavelet transform

    SciTech Connect

    Wang Fei; Zhao Xuezeng; Li Ning

    2010-10-15

    We introduce a multiscale characterization method for line edge roughness (LER) based on redundant second generation wavelet transform. This method involves decomposing LER characteristics into independent bands with different spatial frequency components at different scales, and analyzing the reconstructed signals to work out the roughness exponent, the spatial frequency distribution characteristics, as well as the rms value. The effect of noise can be predicted using detailed signals in the minimum space of scale. This method was applied to numerical profiles for validation. Results show that according to the line edge profiles with similar amplitudes, the roughness exponent R can effectively reflect the degree of irregularity of LER and intuitively provide information on LER spatial frequency distribution.

  8. Size Distributions and Characterization of Native and Ground Samples for Toxicology Studies

    NASA Technical Reports Server (NTRS)

    McKay, David S.; Cooper, Bonnie L.; Taylor, Larry A.

    2010-01-01

    This slide presentation shows charts and graphs that review the particle size distribution and characterization of natural and ground samples for toxicology studies. There are graphs which show the volume distribution versus the number distribution for natural occurring dust, jet mill ground dust, and ball mill ground dust.

  9. Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography.

    PubMed

    Schneider, Simon; Eppler, Florian; Weber, Marco; Olowojoba, Ganiu; Weiss, Patrick; Hübner, Christof; Mikonsaari, Irma; Freude, Wolfgang; Koos, Christian

    2016-01-01

    Nanocomposite materials represent a success story of nanotechnology. However, development of nanomaterial fabrication still suffers from the lack of adequate analysis tools. In particular, achieving and maintaining well-dispersed particle distributions is a key challenge, both in material development and industrial production. Conventional methods like optical or electron microscopy need laborious, costly sample preparation and do not permit fast extraction of nanoscale structural information from statistically relevant sample volumes. Here we show that optical coherence tomography (OCT) represents a versatile tool for nanomaterial characterization, both in a laboratory and in a production environment. The technique does not require sample preparation and is applicable to a wide range of solid and liquid material systems. Large particle agglomerates can be directly found by OCT imaging, whereas dispersed nanoparticles are detected by model-based analysis of depth-dependent backscattering. Using a model system of polystyrene nanoparticles, we demonstrate nanoparticle sizing with high accuracy. We further prove the viability of the approach by characterizing highly relevant material systems based on nanoclays or carbon nanotubes. The technique is perfectly suited for in-line metrology in a production environment, which is demonstrated using a state-of-the-art compounding extruder. These experiments represent the first demonstration of multiscale nanomaterial characterization using OCT. PMID:27557544

  10. Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography

    PubMed Central

    Schneider, Simon; Eppler, Florian; Weber, Marco; Olowojoba, Ganiu; Weiss, Patrick; Hübner, Christof; Mikonsaari, Irma; Freude, Wolfgang; Koos, Christian

    2016-01-01

    Nanocomposite materials represent a success story of nanotechnology. However, development of nanomaterial fabrication still suffers from the lack of adequate analysis tools. In particular, achieving and maintaining well-dispersed particle distributions is a key challenge, both in material development and industrial production. Conventional methods like optical or electron microscopy need laborious, costly sample preparation and do not permit fast extraction of nanoscale structural information from statistically relevant sample volumes. Here we show that optical coherence tomography (OCT) represents a versatile tool for nanomaterial characterization, both in a laboratory and in a production environment. The technique does not require sample preparation and is applicable to a wide range of solid and liquid material systems. Large particle agglomerates can be directly found by OCT imaging, whereas dispersed nanoparticles are detected by model-based analysis of depth-dependent backscattering. Using a model system of polystyrene nanoparticles, we demonstrate nanoparticle sizing with high accuracy. We further prove the viability of the approach by characterizing highly relevant material systems based on nanoclays or carbon nanotubes. The technique is perfectly suited for in-line metrology in a production environment, which is demonstrated using a state-of-the-art compounding extruder. These experiments represent the first demonstration of multiscale nanomaterial characterization using OCT. PMID:27557544

  11. Multiscale Characterization of Deformation Mechanisms in the Weld Joint of a Nickel-based Superalloy

    SciTech Connect

    Barabash, Oleg M.; Horton, Joe; Babu, Suresh; Vitek, John; David, Stan; Ice, Gene; Barabash, Rozaliya

    2007-12-19

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the {gamma} - phase particles during heating and secondary precipitation of {gamma} - phase during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, {gamma} - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (50-70nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the ? matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with typical Burgers vector b=[110]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  12. Multiscale Characterization of Deformation Mechanisms in the Weld Joint of a Nickel-based Superalloy

    SciTech Connect

    Barabash, Oleg M

    2005-01-01

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the {gamma}{prime} - phase particles during heating and secondary precipitation of {gamma}{prime} - phase during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, {gamma}{prime} - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (50-70nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the {gamma} matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with typical Burgers vector b=[110]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  13. Multiscale characterization of deformation mechanisms in the weld joint of a nickel-based superalloy

    SciTech Connect

    Barabash, Oleg M; Horton Jr, Joe A; Babu, Sudarsanam S; Vitek, John Michael; David, Stan A; Ice, Gene E; Barabash, Rozaliya

    2005-01-01

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the gamma' - phase particles during heating and secondary precipitation of gamma' during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, gamma' - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (10-20nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the gamma matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with Burgers vector b=[110] and dislocation lines [1-12] and [1-1-2] ; or b=[-110], dislocation lines [112] and [11-2] . Each of these two dislocation groups forms two Z-shaped dislocation lines fluctuating around two cubic directions [100] and [010]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  14. A Multiscale Vibrational Spectroscopic Approach for Identification and Biochemical Characterization of Pollen

    PubMed Central

    Bağcıoğlu, Murat; Zimmermann, Boris; Kohler, Achim

    2015-01-01

    Background Analysis of pollen grains reveals valuable information on biology, ecology, forensics, climate change, insect migration, food sources and aeroallergens. Vibrational (infrared and Raman) spectroscopies offer chemical characterization of pollen via identifiable spectral features without any sample pretreatment. We have compared the level of chemical information that can be obtained by different multiscale vibrational spectroscopic techniques. Methodology Pollen from 15 different species of Pinales (conifers) were measured by seven infrared and Raman methodologies. In order to obtain infrared spectra, both reflectance and transmission measurements were performed on ground and intact pollen grains (bulk measurements), in addition, infrared spectra were obtained by microspectroscopy of multigrain and single pollen grain measurements. For Raman microspectroscopy measurements, spectra were obtained from the same pollen grains by focusing two different substructures of pollen grain. The spectral data from the seven methodologies were integrated into one data model by the Consensus Principal Component Analysis, in order to obtain the relations between the molecular signatures traced by different techniques. Results The vibrational spectroscopy enabled biochemical characterization of pollen and detection of phylogenetic variation. The spectral differences were clearly connected to specific chemical constituents, such as lipids, carbohydrates, carotenoids and sporopollenins. The extensive differences between pollen of Cedrus and the rest of Pinaceae family were unambiguously connected with molecular composition of sporopollenins in pollen grain wall, while pollen of Picea has apparently higher concentration of carotenoids than the rest of the family. It is shown that vibrational methodologies have great potential for systematic collection of data on ecosystems and that the obtained phylogenetic variation can be well explained by the biochemical composition of

  15. Multi-scale characterization by FIB-SEM/TEM/3DAP.

    PubMed

    Ohkubo, T; Sepehri-Amin, H; Sasaki, T T; Hono, K

    2014-11-01

    In order to improve properties of functional materials, it is important to understand the relation between the structure and the properties since the structure has large effect to the properties. This can be done by using multi-scale microstructure analysis from macro-scale to nano and atomic scale. Scanning electron microscope (SEM) equipped with focused ion beam (FIB), transmission electron microscope (TEM) and 3D atom probe (3DAP) are complementary analysis tools making it possible to know the structure and the chemistry from micron to atomic resolution. SEM gives us overall microstructural and chemical information by various kinds of detectors such as secondary electron, backscattered electron, EDS and EBSD detectors. Also, it is possible to analyze 3D structure and chemistry via FIB serial sectioning. In addition, using TEM we can focus on desired region to get more complementary information from HRTEM/STEM/Lorentz images, SAED/NBD patterns and EDS/EELS to see the detail micro or nano-structure and chemistry. Especially, combination of probe Cs corrector and split EDS detectors with large detector size enable us to analyze the atomic scale elemental distribution. Furthermore, if the specimen has a complicated 3D nanostructure, or we need to analyze light elements such as hydrogen, lithium or boron, 3DAP can be used as the only technique which can visualize and analyze distribution of all constituent atoms of our materials within a few hundreds nm area. Hence, site-specific sample preparation using FIB/SEM is necessary to get desired information from region of interest. Therefore, this complementary analysis combination works very well to understand the detail of materials.In this presentation, we will show the analysis results obtained from some of functional materials by Carl Zeiss CrossBeam 1540EsB FIB/SEM, FEI Tecnai G(2) F30, Titan G2 80-200 TEMs and locally build laser assisted 3DAP. As the one of the example, result of multi-scale characterization for

  16. Multi-scale characterization of surface blistering morphology of helium irradiated W thin films

    NASA Astrophysics Data System (ADS)

    Yang, J. J.; Zhu, H. L.; Wan, Q.; Peng, M. J.; Ran, G.; Tang, J.; Yang, Y. Y.; Liao, J. L.; Liu, N.

    2015-09-01

    Surface blistering morphologies of W thin films irradiated by 30 keV He ion beam were studied quantitatively. It was found that the blistering morphology strongly depends on He fluence. For lower He fluence, the accumulation and growth of He bubbles induce the intrinsic surface blisters with mono-modal size distribution feature. When the He fluence is higher, the film surface morphology exhibits a multi-scale property, including two kinds of surface blisters with different characteristic sizes. In addition to the intrinsic He blisters, film/substrate interface delamination also induces large-sized surface blisters. A strategy based on wavelet transform approach was proposed to distinguish and extract the multi-scale surface blistering morphologies. Then the density, the lateral size and the height of these different blisters were estimated quantitatively, and the effect of He fluence on these geometrical parameters was investigated. Our method could provide a potential tool to describe the irradiation induced surface damage morphology with a multi-scale property.

  17. Synthesis and characterization of xTiO{sub 2}{center_dot}(1 - x){alpha}-Fe{sub 2}O{sub 3} magnetic ceramic nanostructure system

    SciTech Connect

    Sorescu, Monica; Xu, Tianhong; Diamandescu, Lucian

    2010-11-15

    Rutile-doped hematite xTiO{sub 2}{center_dot}(1 - x){alpha}-Fe{sub 2}O{sub 3} (x = 0.0-1.0) nanostructures were synthesized using mechanochemical activation by ball milling. Their complex structural, magnetic and thermal properties were characterized by X-ray diffraction, Moessbauer spectroscopy and simultaneous DSC-TGA. XRD patterns yielded the dependence of lattice parameters and grain size as a function of ball milling time. For the molar concentrations x = 0.1 and 0.3, the Moessbauer spectra were fitted with one, two, three or four sextets, corresponding to the degree of Ti ion substitution of Fe ions in hematite lattice. After 12 h of ball milling, the completion of Ti ion substitution of Fe ions in hematite lattice occurs for x = 0.1 and 0.3. For x = 0.5 and 0.7, Moessbauer spectra fitting required sextets and a quadrupole-split doublet, representing Fe ions substituting Ti ions in the rutile lattice. The completion of Fe ion substitution of Ti ions in rutile lattice was not observed, as indicated by XRD patterns and Moessbauer spectra for these two molar concentrations. Simultaneous DSC-TGA measurements revealed that the mechanochemical activation by ball milling has a strong effect on the thermal behavior of this nanostructure system. The enthalpy dropped dramatically after 2 h of milling time, indicating the strong solid-solid interactions between TiO{sub 2} and {alpha}-Fe{sub 2}O{sub 3} after ball milling. The change in weight loss of hematite was caused by the decrease of grain size and ion substitutions between Fe and Ti after mechanochemical activation.

  18. Multiscale multimodal fusion of histological and MRI volumes for characterization of lung inflammation

    NASA Astrophysics Data System (ADS)

    Rusu, Mirabela; Wang, Haibo; Golden, Thea; Gow, Andrew; Madabhushi, Anant

    2013-03-01

    Mouse lung models facilitate the investigation of conditions such as chronic inflammation which are associated with common lung diseases. The multi-scale manifestation of lung inflammation prompted us to use multi-scale imaging - both in vivo, ex vivo MRI along with ex vivo histology, for its study in a new quantitative way. Some imaging modalities, such as MRI, are non-invasive and capture macroscopic features of the pathology, while others, e.g. ex vivo histology, depict detailed structures. Registering such multi-modal data to the same spatial coordinates will allow the construction of a comprehensive 3D model to enable the multi-scale study of diseases. Moreover, it may facilitate the identification and definition of quantitative of in vivo imaging signatures for diseases and pathologic processes. We introduce a quantitative, image analytic framework to integrate in vivo MR images of the entire mouse with ex vivo histology of the lung alone, using lung ex vivo MRI as conduit to facilitate their co-registration. In our framework, we first align the MR images by registering the in vivo and ex vivo MRI of the lung using an interactive rigid registration approach. Then we reconstruct the 3D volume of the ex vivo histological specimen by efficient group wise registration of the 2D slices. The resulting 3D histologic volume is subsequently registered to the MRI volumes by interactive rigid registration, directly to the ex vivo MRI, and implicitly to in vivo MRI. Qualitative evaluation of the registration framework was performed by comparing airway tree structures in ex vivo MRI and ex vivo histology where airways are visible and may be annotated. We present a use case for evaluation of our co-registration framework in the context of studying chronic inammation in a diseased mouse.

  19. Metal powder reactions in ball milling

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1976-01-01

    On milling chromium powder in three metal chlorides and either chromium or nickel powders in ten organic liquids representative of nine different functional groups, the powders always reacted with the liquids and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 wt%. In most milling runs, compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid, and in most runs with organic liquids H2, CH4, and CO2 were generated.

  20. Multi-scale analysis and characterization of the ITER pre-compression rings

    NASA Astrophysics Data System (ADS)

    Foussat, A.; Park, B.; Rajainmaki, H.

    2014-01-01

    The toroidal field (TF) system of ITER Tokamak composed of 18 "D" shaped Toroidal Field (TF) coils during an operating scenario experiences out-of-plane forces caused by the interaction between the 68kA operating TF current and the poloidal magnetic fields. In order to keep the induced static and cyclic stress range in the intercoil shear keys between coils cases within the ITER allowable limits [1], centripetal preload is introduced by means of S2 fiber-glass/epoxy composite pre-compression rings (PCRs). Those PCRs consist in two sets of three rings, each 5 m in diameter and 337 × 288 mm in cross-section, and are installed at the top and bottom regions to apply a total resultant preload of 70 MN per TF coil equivalent to about 400 MPa hoop stress. Recent developments of composites in the aerospace industry have accelerated the use of advanced composites as primary structural materials. The PCRs represent one of the most challenging composite applications of large dimensions and highly stressed structures operating at 4 K over a long term life. Efficient design of those pre-compression composite structures requires a detailed understanding of both the failure behavior of the structure and the fracture behavior of the material. Due to the inherent difficulties to carry out real scale testing campaign, there is a need to develop simulation tools to predict the multiple complex failure mechanisms in pre-compression rings. A framework contract was placed by ITER Organization with SENER Ingenieria y Sistemas SA to develop multi-scale models representative of the composite structure of the Pre-compression rings based on experimental material data. The predictive modeling based on ABAQUS FEM provides the opportunity both to understand better how PCR composites behave in operating conditions and to support the development of materials by the supplier with enhanced performance to withstand the machine design lifetime of 30,000 cycles. The multi-scale stress analysis has

  1. Microstructural Characterization of Aluminum-Carbon Nanotube Nanocomposites Produced Using Different Dispersion Methods.

    PubMed

    Simões, Sónia; Viana, Filomena; Reis, Marcos A L; Vieira, Manuel F

    2016-06-01

    This research focuses on characterization of the impact of dispersion methods on aluminum-carbon nanotubes (Al-CNTs) nanocomposite structure. Nanocomposites were produced by a conventional powder metallurgy process after the dispersion of the CNTs on the Al powders, using two approaches: (1) the dispersion of CNTs and mixture with Al powders were performed in a single step by ultrasonication; and (2) the CNTs were previously untangled by ultrasonication and then mixed with Al powders by ball milling. Microstructural characterization of Al-CNT nanocomposites was performed by optical microscopy, scanning and transmission electron microscopy, electron backscatter diffraction, and high-resolution transmission electron microscopy (HRTEM). Microstructural characterization revealed that the use of ball milling for mixing CNTs with Al powders promoted the formation of CNT clusters of reduced size, more uniformly dispersed in the matrix, and a nanocomposite of smaller grain size. However, the results of HRTEM and Raman spectroscopy show that ball milling causes higher damage to the CNT structure. The strengthening effect of the CNT is attested by the increase in hardness and tensile strength of the nanocomposites. PMID:26954879

  2. Multi-scale mechanical characterization of highly swollen photo-activated collagen hydrogels.

    PubMed

    Tronci, Giuseppe; Grant, Colin A; Thomson, Neil H; Russell, Stephen J; Wood, David J

    2015-01-01

    Biological hydrogels have been increasingly sought after as wound dressings or scaffolds for regenerative medicine, owing to their inherent biofunctionality in biological environments. Especially in moist wound healing, the ideal material should absorb large amounts of wound exudate while remaining mechanically competent in situ. Despite their large hydration, however, current biological hydrogels still leave much to be desired in terms of mechanical properties in physiological conditions. To address this challenge, a multi-scale approach is presented for the synthetic design of cyto-compatible collagen hydrogels with tunable mechanical properties (from the nano- up to the macro-scale), uniquely high swelling ratios and retained (more than 70%) triple helical features. Type I collagen was covalently functionalized with three different monomers, i.e. 4-vinylbenzyl chloride, glycidyl methacrylate and methacrylic anhydride, respectively. Backbone rigidity, hydrogen-bonding capability and degree of functionalization (F: 16 ± 12-91 ± 7 mol%) of introduced moieties governed the structure-property relationships in resulting collagen networks, so that the swelling ratio (SR: 707 ± 51-1996 ± 182 wt%), bulk compressive modulus (Ec: 30 ± 7-168 ± 40 kPa) and atomic force microscopy elastic modulus (EAFM: 16 ± 2-387 ± 66 kPa) were readily adjusted. Because of their remarkably high swelling and mechanical properties, these tunable collagen hydrogels may be further exploited for the design of advanced dressings for chronic wound care. PMID:25411409

  3. Development and Characterization of Embedded Sensory Particles Using Multi-Scale 3D Digital Image Correlation

    NASA Technical Reports Server (NTRS)

    Cornell, Stephen R.; Leser, William P.; Hochhalter, Jacob D.; Newman, John A.; Hartl, Darren J.

    2014-01-01

    A method for detecting fatigue cracks has been explored at NASA Langley Research Center. Microscopic NiTi shape memory alloy (sensory) particles were embedded in a 7050 aluminum alloy matrix to detect the presence of fatigue cracks. Cracks exhibit an elevated stress field near their tip inducing a martensitic phase transformation in nearby sensory particles. Detectable levels of acoustic energy are emitted upon particle phase transformation such that the existence and location of fatigue cracks can be detected. To test this concept, a fatigue crack was grown in a mode-I single-edge notch fatigue crack growth specimen containing sensory particles. As the crack approached the sensory particles, measurements of particle strain, matrix-particle debonding, and phase transformation behavior of the sensory particles were performed. Full-field deformation measurements were performed using a novel multi-scale optical 3D digital image correlation (DIC) system. This information will be used in a finite element-based study to determine optimal sensory material behavior and density.

  4. Dark-field X-ray microscopy for multiscale structural characterization

    PubMed Central

    Simons, H.; King, A.; Ludwig, W.; Detlefs, C.; Pantleon, W.; Schmidt, S.; Snigireva, I.; Snigirev, A.; Poulsen, H. F.

    2015-01-01

    Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales. Here we present dark-field X-ray microscopy; a non-destructive microscopy technique for the three-dimensional mapping of orientations and stresses on lengths scales from 100 nm to 1 mm within embedded sampling volumes. The technique, which allows ‘zooming’ in and out in both direct and angular space, is demonstrated by an annealing study of plastically deformed aluminium. Facilitating the direct study of the interactions between crystalline elements is a key step towards the formulation and validation of multiscale models that account for the entire heterogeneity of a material. Furthermore, dark-field X-ray microscopy is well suited to applied topics, where the structural evolution of internal nanoscale elements (for example, positioned at interfaces) is crucial to the performance and lifetime of macro-scale devices and components thereof. PMID:25586429

  5. Multi-scale mechanical characterization of highly swollen photo-activated collagen hydrogels

    PubMed Central

    Tronci, Giuseppe; Grant, Colin A.; Thomson, Neil H.; Russell, Stephen J.; Wood, David J.

    2015-01-01

    Biological hydrogels have been increasingly sought after as wound dressings or scaffolds for regenerative medicine, owing to their inherent biofunctionality in biological environments. Especially in moist wound healing, the ideal material should absorb large amounts of wound exudate while remaining mechanically competent in situ. Despite their large hydration, however, current biological hydrogels still leave much to be desired in terms of mechanical properties in physiological conditions. To address this challenge, a multi-scale approach is presented for the synthetic design of cyto-compatible collagen hydrogels with tunable mechanical properties (from the nano- up to the macro-scale), uniquely high swelling ratios and retained (more than 70%) triple helical features. Type I collagen was covalently functionalized with three different monomers, i.e. 4-vinylbenzyl chloride, glycidyl methacrylate and methacrylic anhydride, respectively. Backbone rigidity, hydrogen-bonding capability and degree of functionalization (F: 16 ± 12–91 ± 7 mol%) of introduced moieties governed the structure–property relationships in resulting collagen networks, so that the swelling ratio (SR: 707 ± 51–1996 ± 182 wt%), bulk compressive modulus (Ec: 30 ± 7–168 ± 40 kPa) and atomic force microscopy elastic modulus (EAFM: 16 ± 2–387 ± 66 kPa) were readily adjusted. Because of their remarkably high swelling and mechanical properties, these tunable collagen hydrogels may be further exploited for the design of advanced dressings for chronic wound care. PMID:25411409

  6. Multiscale fracture network characterization and impact on flow: A case study on the Latemar carbonate platform

    NASA Astrophysics Data System (ADS)

    Hardebol, N. J.; Maier, C.; Nick, H.; Geiger, S.; Bertotti, G.; Boro, H.

    2015-12-01

    A fracture network arrangement is quantified across an isolated carbonate platform from outcrop and aerial imagery to address its impact on fluid flow. The network is described in terms of fracture density, orientation, and length distribution parameters. Of particular interest is the role of fracture cross connections and abutments on the effective permeability. Hence, the flow simulations explicitly account for network topology by adopting Discrete-Fracture-and-Matrix description. The interior of the Latemar carbonate platform (Dolomites, Italy) is taken as outcrop analogue for subsurface reservoirs of isolated carbonate build-ups that exhibit a fracture-dominated permeability. New is our dual strategy to describe the fracture network both as deterministic- and stochastic-based inputs for flow simulations. The fracture geometries are captured explicitly and form a multiscale data set by integration of interpretations from outcrops, airborne imagery, and lidar. The deterministic network descriptions form the basis for descriptive rules that are diagnostic of the complex natural fracture arrangement. The fracture networks exhibit a variable degree of multitier hierarchies with smaller-sized fractures abutting against larger fractures under both right and oblique angles. The influence of network topology on connectivity is quantified using Discrete-Fracture-Single phase fluid flow simulations. The simulation results show that the effective permeability for the fracture and matrix ensemble can be 50 to 400 times higher than the matrix permeability of 1.0 · 10-14 m2. The permeability enhancement is strongly controlled by the connectivity of the fracture network. Therefore, the degree of intersecting and abutting fractures should be captured from outcrops with accuracy to be of value as analogue.

  7. Reconstruction and Quantitative Characterization of Multiphase, Multiscale Three-Dimensional Microstructure of a Cast Al-Si Base Alloy

    NASA Astrophysics Data System (ADS)

    Singh, H.; Gokhale, A. M.; Mao, Y.; Tewari, A.; Sachdev, A. K.

    2009-12-01

    The serial sectioning technique is well known for the reconstruction of three-dimensional (3D) microstructures of opaque materials. In recent years, techniques also have been developed for the reconstruction of high-fidelity, large-volume segments of 3D microstructures that use montage serial sections and robot-assisted automated acquisitions of montage serial sections. This article reports the reconstruction of the multiphase, multiscale 3D microstructure of a permanent mold cast unmodified Al-12 wt pct Si-1 wt pct Ni base alloy that contains eutectic Si platelets, coarse primary polyhedral Si particles, Fe-rich script intermetallic particles, and pores. These constituents are segmented, reconstructed, rendered, and characterized in three dimensions. The estimated 3D microstrucutral attributes include the distribution of eutectic platelet thickness; the mean volume, mean surface area, and mean thickness of the eutectic Si platelets; the mean volume and the mean surface area of the polyhedral primary Si particles; and the mean number of faces, edges, and corners on the polyhedral primary Si particles.

  8. Formation mechanism of calcified roots in terrestrial sediments: insights from a multitechnique and multiscale characterization strategy

    NASA Astrophysics Data System (ADS)

    El Khatib, Rime; Huguet, Arnaud; Bernard, Sylvain; Gocke, Martina; Wiesenberg, Guido; Derenne, Sylvie

    2015-04-01

    Root remains encrusted by secondary carbonates, e.g. carbonated rhizoliths, are common in many soils and terrestrial sediments from various environmental settings. Rhizoliths usually exhibit a cylindrical shape and may have different sizes (from a few µm up to several cm). These objects have been known for ages and intensively used as proxies for paleoenvironmental reconstruction. It is generally assumed that such encrustation is controlled or induced by complex organic-mineral interactions at the plant tissue scale, even though this has never been investigated in detail. The aim of this work was to better constrain the mechanisms of rhizolith formation, which remain unclear so far. Rhizoliths at different stages of encrustation and surrounding sediment were sampled at different depths from a loess-paleosol sequence (Nussloch, SW Germany). They were characterised using a multi-scale and multi-technique approach. The use of SEM and TEM to investigate rhizolith samples has offered a unique combination of chemical and structural information with submicrometer spatial resolution, while solid-state 13C NMR of decarbonated rhizoliths along with liquid and gas chromatography analyses of organic extracts have provided information at a molecular level. SEM and TEM reveal that the precipitation of secondary carbonates does not only occur around, but also within the plant root cells and evidence the close relationship existing between organic and inorganic phases within these complex systems. The fine-scale preservation of root cellular ultrastructure with remarkable integrity observed for samples at all stages of encrustation has likely been promoted by this intra-cellular carbonate precipitation. In parallel, gas and liquid chromatography analyses showed that microbial biomarkers were predominant in the former roots, in contrast with the surrounding sediment, dominated by plant biomarkers. This suggests that the molecular signatures of the organic matter differ between

  9. Microstructure and optical characterizations of mechanosynthesized nanocrystalline semiconducting ZrTiO4 compound

    NASA Astrophysics Data System (ADS)

    Dutta, Hema; Nandy, Anshuman; Pradhan, S. K.

    2016-08-01

    A ZrO2-TiO2 solid solution is obtained by high energy ball milling of equimolar mixture of monoclinic (m) ZrO2 and anatase (a) TiO2. Nanocrystalline orthorhombic ZrTiO4 compound is initiated from the nucleation of TiO2-ZrO2 solid solution with isostructural s-TiO2 (srilankite) base after 30 min of milling. After 12 h of milling, 95 mol% non-stoichiometric ZrTiO4 phase is formed. Post-annealing of 12 h ball-milled powder mixture at 1073 K for 1 h in open air results in complete formation of stoichiometric ZrTiO4 compound. Microstructures of all powder mixtures milled for different durations have been characterized by Rietveld's structure and microstructure refinement method using X-ray powder diffraction data. HRTEM images of 12 h milled and annealed samples provide direct evidence of the results obtained from the Rietveld analysis. Optical bandgaps of ball milled and annealed ZrTiO4 compounds lie within the semiconducting region (~2.0 eV) and increases with increase in milling time.

  10. Multi-scale Characterization and Modeling of Surface Slope Probability Distribution for ~20-km Diameter Lunar Craters

    NASA Astrophysics Data System (ADS)

    Mahanti, P.; Robinson, M. S.; Boyd, A. K.

    2013-12-01

    Craters ~20-km diameter and above significantly shaped the lunar landscape. The statistical nature of the slope distribution on their walls and floors dominate the overall slope distribution statistics for the lunar surface. Slope statistics are inherently useful for characterizing the current topography of the surface, determining accurate photometric and surface scattering properties, and in defining lunar surface trafficability [1-4]. Earlier experimental studies on the statistical nature of lunar surface slopes were restricted either by resolution limits (Apollo era photogrammetric studies) or by model error considerations (photoclinometric and radar scattering studies) where the true nature of slope probability distribution was not discernible at baselines smaller than a kilometer[2,3,5]. Accordingly, historical modeling of lunar surface slopes probability distributions for applications such as in scattering theory development or rover traversability assessment is more general in nature (use of simple statistical models such as the Gaussian distribution[1,2,5,6]). With the advent of high resolution, high precision topographic models of the Moon[7,8], slopes in lunar craters can now be obtained at baselines as low as 6-meters allowing unprecedented multi-scale (multiple baselines) modeling possibilities for slope probability distributions. Topographic analysis (Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) 2-m digital elevation models (DEM)) of ~20-km diameter Copernican lunar craters revealed generally steep slopes on interior walls (30° to 36°, locally exceeding 40°) over 15-meter baselines[9]. In this work, we extend the analysis from a probability distribution modeling point-of-view with NAC DEMs to characterize the slope statistics for the floors and walls for the same ~20-km Copernican lunar craters. The difference in slope standard deviations between the Gaussian approximation and the actual distribution (2-meter sampling) was

  11. A Comprehensive Specimen-Specific Multiscale Data Set for Anatomical and Mechanical Characterization of the Tibiofemoral Joint

    PubMed Central

    Chokhandre, Snehal; Colbrunn, Robb; Bennetts, Craig; Erdemir, Ahmet

    2015-01-01

    Understanding of tibiofemoral joint mechanics at multiple spatial scales is essential for developing effective preventive measures and treatments for both pathology and injury management. Currently, there is a distinct lack of specimen-specific biomechanical data at multiple spatial scales, e.g., joint, tissue, and cell scales. Comprehensive multiscale data may improve the understanding of the relationship between biomechanical and anatomical markers across various scales. Furthermore, specimen-specific multiscale data for the tibiofemoral joint may assist development and validation of specimen-specific computational models that may be useful for more thorough analyses of the biomechanical behavior of the joint. This study describes an aggregation of procedures for acquisition of multiscale anatomical and biomechanical data for the tibiofemoral joint. Magnetic resonance imaging was used to acquire anatomical morphology at the joint scale. A robotic testing system was used to quantify joint level biomechanical response under various loading scenarios. Tissue level material properties were obtained from the same specimen for the femoral and tibial articular cartilage, medial and lateral menisci, anterior and posterior cruciate ligaments, and medial and lateral collateral ligaments. Histology data were also obtained for all tissue types to measure specimen-specific cell scale information, e.g., cellular distribution. This study is the first of its kind to establish a comprehensive multiscale data set for a musculoskeletal joint and the presented data collection approach can be used as a general template to guide acquisition of specimen-specific comprehensive multiscale data for musculoskeletal joints. PMID:26381404

  12. Multi-scale simulation flow and multi-scale materials characterization for stress management in 3D through-silicon-via integration technologies - Effect of stress on 3D IC interconnect reliability

    NASA Astrophysics Data System (ADS)

    Sukharev, Valeriy; Zschech, Ehrenfried

    2014-06-01

    The paper addresses the growing need in a simulation-based design verification flow capable to analyze any design of 3D IC stacks and to determine across-layers implications in 3D IC reliability caused by through-silicon-via (TSV) and chip-package interaction (CPI) induced mechanical stresses. The limited characterization/measurement capabilities of 3D IC stacks and a strict "good die" requirement make this type of analysis really critical for the achievement of an acceptable level of functional and parametric yield and reliability. The paper focuses on the development of a design-for-manufacturability (DFM) type of methodology for managing mechanical stresses during a sequence of designs of 3D TSV-based dies, stacks and packages. A set of physics-based compact models for a multi-scale simulation, to assess the mechanical stress across the dies stacked and packaged with the 3D TSV technology, is proposed. As an example the effect of CPI/TSV induced stresses on stress migration (SM) and electromigration (EM) in the back-end-of-line (BEoL) and backside-redistribution-layer (BRDL) interconnect lines is considered. A strategy for a simulation feeding data generation and a respective materials characterization approach are proposed, with the goal to generate a database for multi-scale material parameters of wafer-level and package-level structures. A calibration technique based on fitting the simulation results to measured stress components and electrical characteristics of the test-chip devices is discussed.

  13. Multiscale microstructural characterization of Sn-rich alloys by three dimensional (3D) X-ray synchrotron tomography and focused ion beam (FIB) tomography

    SciTech Connect

    Yazzie, K.E.; Williams, J.J.; Phillips, N.C.; De Carlo, F.; Chawla, N.

    2012-08-15

    Sn-rich (Pb-free) alloys serve as electrical and mechanical interconnects in electronic packaging. It is critical to quantify the microstructures of Sn-rich alloys to obtain a fundamental understanding of their properties. In this work, the intermetallic precipitates in Sn-3.5Ag and Sn-0.7Cu, and globular lamellae in Sn-37Pb solder joints were visualized and quantified using 3D X-ray synchrotron tomography and focused ion beam (FIB) tomography. 3D reconstructions were analyzed to extract statistics on particle size and spatial distribution. In the Sn-Pb alloy the interconnectivity of Sn-rich and Pb-rich constituents was quantified. It will be shown that multiscale characterization using 3D X-ray and FIB tomography enabled the characterization of the complex morphology, distribution, and statistics of precipitates and contiguous phases over a range of length scales. - Highlights: Black-Right-Pointing-Pointer Multiscale characterization by X-ray synchrotron and focused ion beam tomography. Black-Right-Pointing-Pointer Characterized microstructural features in several Sn-based alloys. Black-Right-Pointing-Pointer Quantified size, fraction, and clustering of microstructural features.

  14. A multi-scale morphological characterization of extended TeV survey sources

    NASA Astrophysics Data System (ADS)

    Schwarzburg, S.; Pühlhofer, G.; Santangelo, A.

    2012-12-01

    A recurrent topic in very high energy γ-ray astronomy is the morphological characterization of extended sources, which are lacking a clear counterpart in other wavelengths. Whithout a counterpart, the shape of such a source is not known a priori. Therefore blind/unbiased approaches are required to describe such a newly detected source in terms of detached emission regions (``features'') or eventually even separate objects. Ideally, the search takes into account the observation statistic and the instrument response (e.g. the exposure and the point spread function). And finally, a detection significance for the features needs to be provided.

  15. Solid-state characterization and dissolution properties of meloxicam-moringa coagulant-PVP ternary solid dispersions.

    PubMed

    Noolkar, Suhail B; Jadhav, Namdeo R; Bhende, Santosh A; Killedar, Suresh G

    2013-06-01

    The effect of ternary solid dispersions of poor water-soluble NSAID meloxicam with moringa coagulant (obtained by salt extraction of moringa seeds) and polyvinylpyrrolidone on the in vitro dissolution properties has been investigated. Binary (meloxicam-moringa and meloxicam-polyvinylpyrrolidone (PVP)) and ternary (meloxicam-moringa-PVP) systems were prepared by physical kneading and ball milling and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffractometry. The in vitro dissolution behavior of meloxicam from the different products was evaluated by means of United States Pharmacopeia type II dissolution apparatus. The results of solid-state studies indicated the presence of strong interactions between meloxicam, moringa, and PVP which were of totally amorphous nature. All ternary combinations were significantly more effective than the corresponding binary systems in improving the dissolution rate of meloxicam. The best performance in this respect was given by the ternary combination employing meloxicam-moringa-PVP ratio of [1:(3:1)] prepared by ball milling, with about six times increase in percent dissolution rate, whereas meloxicam-moringa (1:3) and meloxicam-PVP (1:4) prepared by ball milling improved dissolution of meloxicam by almost 3- and 2.5-folds, respectively. The achieved excellent dissolution enhancement of meloxicam in the ternary systems was attributed to the combined effects of impartation of hydrophilic characteristic by PVP, as well as to the synergistic interaction between moringa and PVP. PMID:23483432

  16. Multiscale characterization of chemical–mechanical interactions between polymer fibers and cementitious matrix

    SciTech Connect

    Hernández-Cruz, Daniel; Hargis, Craig W.; Bae, Sungchul; Itty, Pierre A.; Meral, Cagla; Dominowski, Jolee; Radler, Michael J.; Kilcoyne, David A.; Monteiro, Paulo J. M.

    2014-04-01

    Together with a series of mechanical tests, the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (lCT). Experimental results showed that these techniques have great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber the polypropylene core and the ethylene acrylic acid copolymer sheath. Similarly, chemical interactions between the hybrid fiber and the cement hydration products were observed, indicating the chemical bonding between the sheath and the hardened cement paste matrix. Microtomography allowed visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars.

  17. Characterization of Piezoelectric PDMS-Nanoparticle Composites

    NASA Astrophysics Data System (ADS)

    Borsa, C. J.; Mionic Ebersold, M.; Bowen, P.; Farine, P.-A.; Briand, D.

    2015-12-01

    In this work, the novel fabrication and characterization of elastomeric piezoelectric nanocomposites are explored. Fabrication methods explored herein utilize ball milled barium titanate powder dispersions, along with double walled carbon nanotubes which are dispersed in toluene though the use of an ultrasonic probe. Test devices are then constructed with electrodes made from evaporated gold on polyimide foils and protective dielectrics of pristine PDMS. Two different device construction methods are explored utilizing both direct contact bonding and plasma bonding of the active composite layers to the dielectric/electrode. Test samples are evaluated through the use of a dedicated Berlincourt type piezoelectric d33 meter.

  18. Multiscale modeling and characterization for performance and safety of lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Pannala, S.; Turner, J. A.; Allu, S.; Elwasif, W. R.; Kalnaus, S.; Simunovic, S.; Kumar, A.; Billings, J. J.; Wang, H.; Nanda, J.

    2015-08-01

    Lithium-ion batteries are highly complex electrochemical systems whose performance and safety are governed by coupled nonlinear electrochemical-electrical-thermal-mechanical processes over a range of spatiotemporal scales. Gaining an understanding of the role of these processes as well as development of predictive capabilities for design of better performing batteries requires synergy between theory, modeling, and simulation, and fundamental experimental work to support the models. This paper presents the overview of the work performed by the authors aligned with both experimental and computational efforts. In this paper, we describe a new, open source computational environment for battery simulations with an initial focus on lithium-ion systems but designed to support a variety of model types and formulations. This system has been used to create a three-dimensional cell and battery pack models that explicitly simulate all the battery components (current collectors, electrodes, and separator). The models are used to predict battery performance under normal operations and to study thermal and mechanical safety aspects under adverse conditions. This paper also provides an overview of the experimental techniques to obtain crucial validation data to benchmark the simulations at various scales for performance as well as abuse. We detail some initial validation using characterization experiments such as infrared and neutron imaging and micro-Raman mapping. In addition, we identify opportunities for future integration of theory, modeling, and experiments.

  19. Multiscale modeling and characterization for performance and safety of lithium-ion batteries

    SciTech Connect

    Pannala, S. Turner, J. A.; Allu, S.; Elwasif, W. R.; Kalnaus, S.; Simunovic, S.; Kumar, A.; Billings, J. J.; Wang, H.; Nanda, J.

    2015-08-21

    Lithium-ion batteries are highly complex electrochemical systems whose performance and safety are governed by coupled nonlinear electrochemical-electrical-thermal-mechanical processes over a range of spatiotemporal scales. Gaining an understanding of the role of these processes as well as development of predictive capabilities for design of better performing batteries requires synergy between theory, modeling, and simulation, and fundamental experimental work to support the models. This paper presents the overview of the work performed by the authors aligned with both experimental and computational efforts. In this paper, we describe a new, open source computational environment for battery simulations with an initial focus on lithium-ion systems but designed to support a variety of model types and formulations. This system has been used to create a three-dimensional cell and battery pack models that explicitly simulate all the battery components (current collectors, electrodes, and separator). The models are used to predict battery performance under normal operations and to study thermal and mechanical safety aspects under adverse conditions. This paper also provides an overview of the experimental techniques to obtain crucial validation data to benchmark the simulations at various scales for performance as well as abuse. We detail some initial validation using characterization experiments such as infrared and neutron imaging and micro-Raman mapping. In addition, we identify opportunities for future integration of theory, modeling, and experiments.

  20. Multiscale characterization of pore size distributions using mercury porosimetry and nitrogen adsorption

    NASA Astrophysics Data System (ADS)

    Paz-Ferreiro, J.; Tarquis, A. M.; Miranda, J. G. V.; Vidal Vázquez, E.

    2009-04-01

    The soil pore space is a continuum extremely variable in size, including structures smaller than nanometres and as large as macropores or cracks with millimetres or even centimetres size. Pore size distributions (PSDs) affects important soil functions, such as those related with transmission and storage of water, and root growth. Direct and indirect measurements of PSDs are becoming increasingly used to characterize soil structure. Mercury injection porosimetry and nitrogen adsorption isotherms are techniques commonly employed for assessing equivalent pore size diameters in the range from about 50 nm to 100 m and 2 to 500 nm, respectively. The multifractal formalism was used to describe Hg injection curves and N2 adsorption isotherms from two series of a Mollisol cultivated under no tillage and minimum tillage. Soil samples were taken from 0-10, 10-20 and 20-30 cm depths in two experimental fields located in the north of Buenos Aires and South of Santa Fe provinces, Argentina. All the data sets analyzed from the two studied soil attributes showed remarkably good scaling trends as assessed by singularity spectrum and generalized dimension spectrum. Both, experimental Hg injection curves and N2 adsorption isotherms could be fitted reasonably well with multifractal models. A wide variety of singularity and generalized dimension spectra was found for the variables. The capacity dimensions, D0, for both Hg injection and N2 adsorption data were not significantly different from the Euclidean dimension. However, the entropy dimension, D1, and correlation dimension, D2, obtained from mercury injection and nitrogen adsorption data showed significant differences. So, D1 values were on average 0.868 and varied from 0.787 to 0.925 for Hg intrusion curves. Entropy dimension, D1, values for N2 adsorption isotherms were on average 0.582 significantly lower than those obtained when using the former technique. Twenty-three out of twenty-four N2 isotherms had D1 values in a

  1. Multi-physics and multi-scale characterization of shale anisotropy

    NASA Astrophysics Data System (ADS)

    Sarout, J.; Nadri, D.; Delle Piane, C.; Esteban, L.; Dewhurst, D.; Clennell, M. B.

    2012-12-01

    Shales are the most abundant sedimentary rock type in the Earth's shallow crust. In the past decade or so, they have attracted increased attention from the petroleum industry as reservoirs, as well as more traditionally for their sealing capacity for hydrocarbon/CO2 traps or underground waste repositories. The effectiveness of both fundamental and applied shale research is currently limited by (i) the extreme variability of physical, mechanical and chemical properties observed for these rocks, and by (ii) the scarce data currently available. The variability in observed properties is poorly understood due to many factors that are often irrelevant for other sedimentary rocks. The relationships between these properties and the petrophysical measurements performed at the field and laboratory scales are not straightforward, translating to a scale dependency typical of shale behaviour. In addition, the complex and often anisotropic micro-/meso-structures of shales give rise to a directional dependency of some of the measured physical properties that are tensorial by nature such as permeability or elastic stiffness. Currently, fundamental understanding of the parameters controlling the directional and scale dependency of shale properties is far from complete. Selected results of a multi-physics laboratory investigation of the directional and scale dependency of some critical shale properties are reported. In particular, anisotropic features of shale micro-/meso-structures are related to the directional-dependency of elastic and fluid transport properties: - Micro-/meso-structure (μm to cm scale) characterization by electron microscopy and X-ray tomography; - Estimation of elastic anisotropy parameters on a single specimen using elastic wave propagation (cm scale); - Estimation of the permeability tensor using the steady-state method on orthogonal specimens (cm scale); - Estimation of the low-frequency diffusivity tensor using NMR method on orthogonal specimens (<

  2. Multi-scale lidar-based approaches to characterizing stream networks, surface roughness and landforms of forest watersheds

    NASA Astrophysics Data System (ADS)

    Brubaker, Kristen M.

    these formations, there was a difference in both vegetation community and structure based on formation. Similar formations were calculated for a broader region of the Ridge and Valley Province and vegetation communities on formations were identified. There was association between the identified vegetation community and the delineated formation. Overall, methodologies were developed to explore properties of forested ecosystems in the Ridge and Valley Province. Using lidar elevation data, delineation of the stream network and characterization of terrain and micro-topography were all improved, and curvature was utilized to help classify the landforms in watershed. Further research should attempt to validate these results across a broader area, as well as work to develop techniques to use together to create a multi-scale, hierarchical classification system incorporating hydrologic data, surface roughness, and landscape level terrain data.

  3. Multiscale structural characterizations of mixed U(iv)-An(iii) oxalates (An(iii) = Pu or Am) combining XAS and XRD measurements.

    PubMed

    Arab-Chapelet, B; Martin, P M; Costenoble, S; Delahaye, T; Scheinost, A C; Grandjean, S; Abraham, F

    2016-04-28

    Mixed actinide(III,IV) oxalates of the general formula M2.2UAn(C2O4)5·nH2O (An = Pu or Am and M = H3O(+) and N2H5(+)) have been quantitatively precipitated by oxalic precipitation in nitric acid medium (yield >99%). Thorough multiscale structural characterization using XRD and XAS measurements confirmed the existence of mixed actinide oxalate solid solutions. The XANES analysis confirmed that the oxidation states of the metallic cations, tetravalent for uranium and trivalent for plutonium and americium, are maintained during the precipitation step. EXAFS measurements show that the local environments around U(+IV), Pu(+III) and Am(+III) are comparable, and the actinides are surrounded by ten oxygen atoms from five bidentate oxalate anions. The mean metal-oxygen distances obtained by XAS measurements are in agreement with those calculated from XRD lattice parameters. PMID:26979820

  4. Isolation and characterization of lignins from Eucalyptus tereticornis (12ABL).

    PubMed

    Zhang, Aiping; Lu, Fachuang; Liu, Chuanfu; Sun, Run-Cang

    2010-11-10

    A three-step sequential extraction-precipitation method was used to isolate lignin from Eucalyptus tereticornis. The ball-milled eucalyptus was extracted with 96% dioxane, 50% dioxane, and 80% dioxane containing 1% NaOH at boiling temperature, consecutively resulting in solubilization of lignin and hemicelluloses. By precipitating such solutions into 70% aqueous ethanol, the hemicelluloses were removed substantially although there were still some carbohydrates left over, especially for lignin fraction extracted by 50% dioxane. Lignins dissolved in the 70% ethanol solutions were recovered via concentration and precipitation into acidified water. About 37% of the original lignin was released following such procedure whereas only 13.5% can be isolated by traditional milled wood lignin (MWL) method. The obtained lignin fractions were analyzed by high performance anion exchange chromatography (HPAEC) following acid hydrolysis for sugar composition of the contaminating carbohydrates and characterized by quantitative (31)P NMR as well as two-dimensional heteronuclear single-quantum coherence ((13)C-(1)H) NMR. The results showed that 96% aqueous dioxane extraction of ball-milled wood under conditions used in this study resulted in lignin preparation with very similar structures and sugar composition as traditional MWL. Therefore extracting ball-milled wood with 96% aqueous dioxane produced lignin in 33.6% yield, which makes it very attractive as an alternative to the traditional MWL method. However further extraction with 50% aqueous dioxane or 80% aqueous dioxane containing 1% NaOH gave just a little more lignins with different carbohydrate compositions from those in MWL. The eucalyptus lignins obtained were syringyl and guaiacyl type units. Lignin fraction obtained from 96% dioxane extraction was found to have more phenolic hydroxyl and less aliphatic hydroxyl than the other two preparations. PMID:20954709

  5. MULTISCALE PHENOMENA IN MATERIALS

    SciTech Connect

    A. BISHOP

    2000-09-01

    This project developed and supported a technology base in nonequilibrium phenomena underpinning fundamental issues in condensed matter and materials science, and applied this technology to selected problems. In this way the increasingly sophisticated synthesis and characterization available for classes of complex electronic and structural materials provided a testbed for nonlinear science, while nonlinear and nonequilibrium techniques helped advance our understanding of the scientific principles underlying the control of material microstructure, their evolution, fundamental to macroscopic functionalities. The project focused on overlapping areas of emerging thrusts and programs in the Los Alamos materials community for which nonlinear and nonequilibrium approaches will have decisive roles and where productive teamwork among elements of modeling, simulations, synthesis, characterization and applications could be anticipated--particularly multiscale and nonequilibrium phenomena, and complex matter in and between fields of soft, hard and biomimetic materials. Principal topics were: (i) Complex organic and inorganic electronic materials, including hard, soft and biomimetic materials, self-assembly processes and photophysics; (ii) Microstructure and evolution in multiscale and hierarchical materials, including dynamic fracture and friction, dislocation and large-scale deformation, metastability, and inhomogeneity; and (iii) Equilibrium and nonequilibrium phases and phase transformations, emphasizing competing interactions, frustration, landscapes, glassy and stochastic dynamics, and energy focusing.

  6. The multiscale analysis between stock market time series

    NASA Astrophysics Data System (ADS)

    Shi, Wenbin; Shang, Pengjian

    2015-11-01

    This paper is devoted to multiscale cross-correlation analysis on stock market time series, where multiscale DCCA cross-correlation coefficient as well as multiscale cross-sample entropy (MSCE) is applied. Multiscale DCCA cross-correlation coefficient is a realization of DCCA cross-correlation coefficient on multiple scales. The results of this method present a good scaling characterization. More significantly, this method is able to group stock markets by areas. Compared to multiscale DCCA cross-correlation coefficient, MSCE presents a more remarkable scaling characterization and the value of each log return of financial time series decreases with the increasing of scale factor. But the results of grouping is not as good as multiscale DCCA cross-correlation coefficient.

  7. Dispersion of halloysite loaded with natural antimicrobials into pectins: Characterization and controlled release analysis.

    PubMed

    Gorrasi, Giuliana

    2015-01-01

    This paper reports the preparation and characterization of green composites based on pectins and nano-hybrids composed of halloysite nanotubes (HNTs) loaded with rosemary essential oil. Different hybrid percentages were mixed into a pectin matrix, by ball milling in the presence of water. Cast films were obtained and analyzed. Structural organization and physical properties (thermal, mechanical, barrier to water vapor) were correlated to the nano-hybrid content. A preliminary study on the kinetics of release of the rosmarinic acid, chosen as a model molecule, was also performed. This work showed the potential of these systems in the active packaging field where controlled release of active species is required. PMID:25965455

  8. An Integrated Multi-Scale Approach to the Study of Evapotranspiration on the Alaskan North Slope: Preliminary Characterization of Fluxes and Turbulence in the Imnavait Creek Basin

    NASA Astrophysics Data System (ADS)

    Wyatt, C.; Mumm, J.; Trochim, E.; Fochesatto, G. J.; Prakash, A.; Anderson, M. C.; Kane, D. L.

    2009-12-01

    Evapotranspiration (ET) plays a significant role in the hydrologic cycle of Arctic basins. Surface-atmosphere exchanges due to ET in the Imnaviat Creek Basin are estimated from water balance computations to be about 74% of summer precipitation or 50% of annual precipitation. Even though ET is a significant component of the hydrologic cycle in this region, the bulk estimates don't accurately account for spatial and temporal variability due to vegetation type, topography, etc. A preliminary experiment was carried out in the summer of 2009 to characterize the turbulent fluxes (i.e. buoyancy fluxes) at two levels of 1 and 3 m AGL and the heat fluxes in an integrated horizontal path covering about 80% of the basin. We present the preliminary analysis and characterization of the turbulent fluxes in the basin and we discuss the design of a multi-scale experimental and modeling approach to the study of ET that integrates point, spatial and volumetric in situ measurements, up to satellite scale observations. This ultimate focus of this exercise is to develop a consistent satellite-based ET retrieval approach.

  9. A multi-scale approach to characterize pure CH4, CF4, and CH4/CF4 mixtures

    NASA Astrophysics Data System (ADS)

    Chattoraj, Joyjit; Risthaus, Tobias; Rubner, Oliver; Heuer, Andreas; Grimme, Stefan

    2015-04-01

    In this study, we develop three intermolecular potentials for methane (CH4), tetrafluoromethane (CF4), and CH4/CF4 dimers using a novel ab initio method. The ultimate goal is to understand microscopically the phase-separation in CH4/CF4 systems, which takes place in the liquid states near their freezing points. Monte-Carlo (MC) simulations of the pure CH4 system are performed using the ab initio energies to verify the potential. The simulations reproduce quite well the experimentally known liquid densities, the internal energies, the second virial coefficients, and the radial distribution function. The essentially six-dimensional (6D) ab initio potential is then reduced to a one-dimensional (1D) effective potential using the inverse Monte-Carlo technique. This potential, too, successfully reproduces the experimental results. Interestingly, the MC study cannot be extended to the pure CF4 system and the CH4/CF4 mixed system because the two respective ab initio potentials present very rough potential landscapes. This renders the interpolation of energies for the MC simulations and thus the multi-scale approach unreliable. It suggests, however, a possible driving force for the experimentally observed phase separation of the CH4/CF4 system at low temperatures. Furthermore, we carefully study the determination of 1D effective potentials via inverse MC techniques. We argue that to a good approximation the temperature dependence of the 1D potentials can be estimated via reweighting techniques for a fixed temperature.

  10. Multi-scale Characterization of the Energy Landscape of Proteins with Application to the C3d/Efb-C Complex

    PubMed Central

    Haspel, Nurit; Geisbrecht, Brian V.; Lambris, John; Kavraki, Lydia

    2009-01-01

    We present a novel multi-level methodology to explore and characterize the low energy landscape and the thermodynamics of proteins. Traditional conformational search methods typically explore only a small portion of the conformational space of proteins and are hard to apply to large proteins due to the large amount of calculations required. In our multi-scale approach, we first provide an initial characterization of the equilibrium state ensemble of a protein using an efficient computational conformational sampling method. We then enrich the obtained ensemble by performing short Molecular Dynamics (MD) simulations on selected conformations from the ensembles as starting points. To facilitate the analysis of the results we project the resulting conformations on a low-dimensional landscape to efficiently focus on important interactions and examine low energy regions. This methodology provides a more extensive sampling of the low energy landscape than an MD simulation starting from a single crystal structure as it explores multiple trajectories of the protein. This enables us to obtain a broader view of the dynamics of proteins and it can help in understanding complex binding, improving docking results and more. In this work we apply the methodology to provide an extensive characterization of the bound complexes of the C3d fragment of human Complement component C3 and one of its powerful bacterial inhibitors, the inhibitory domain of Staphylococcus aureus extra-cellular fibrinogen-binding domain (Efb-C) and two of its mutants. We characterize several important interactions along the binding interface and define low free energy regions in the three complexes. PMID:19899169

  11. Enhancing the high-rate performance of Li4Ti5O12 anode material for lithium-ion battery by a wet ball milling assisted solid-state reaction and ultra-high speed nano-pulverization

    NASA Astrophysics Data System (ADS)

    Huang, Zhao; Wang, Dan; Lin, Ye; Wu, Xiaoyan; Yan, Peng; Zhang, Chunming; He, Dannong

    2014-11-01

    Li4Ti5O12 was successfully synthesized by a modified solid-state reaction method with an in situ coating process. The powders were characterized by X-ray diffraction, BET surface area and scanning electron microscopy. Sub-micron Li4Ti5O12 oxides, with a high phase purity and accurate stoichiometry, were obtained after calcination at 800 °C for 7 h. The pure Li4Ti5O12 electrode material showed a much higher surface area and specific capacity than the one without the ultra-high speed nano-pulverization pretreatment process. Excellent reversible high-rate capability was achieved as 137 mAh g-1 at 10C, 107 mAh g-1 at 20C, 76 mAh g-1 at 40C. The result of the cycling performance showed high capacity retention of about 100% for all charge/discharge rates after 10 cycles. Electrochemical impedance spectra tests demonstrated that the lithium-ion diffusivity in Li4Ti5O12 was improved significantly after the pretreatment, which indicated that the ultra-high speed nano-pulverization treated Li4Ti5O12 with high dispersion and smooth particle surface would be a promising high-rate anode material for lithium-ion battery.

  12. Magnetospheric Multiscale (MMS) Orbit

    NASA Video Gallery

    This animation shows the orbits of Magnetospheric Multiscale (MMS) mission, a Solar-Terrestrial Probe mission comprising of four identically instrumented spacecraft that will study the Earth's magn...

  13. Multi-scale remote sensing sagebrush characterization with regression trees over Wyoming, USA: laying a foundation for monitoring

    USGS Publications Warehouse

    Homer, Collin G.; Aldridge, Cameron L.; Meyer, Debra K.; Schell, Spencer J.

    2012-01-01

    agebrush ecosystems in North America have experienced extensive degradation since European settlement. Further degradation continues from exotic invasive plants, altered fire frequency, intensive grazing practices, oil and gas development, and climate change – adding urgency to the need for ecosystem-wide understanding. Remote sensing is often identified as a key information source to facilitate ecosystem-wide characterization, monitoring, and analysis; however, approaches that characterize sagebrush with sufficient and accurate local detail across large enough areas to support this paradigm are unavailable. We describe the development of a new remote sensing sagebrush characterization approach for the state of Wyoming, U.S.A. This approach integrates 2.4 m QuickBird, 30 m Landsat TM, and 56 m AWiFS imagery into the characterization of four primary continuous field components including percent bare ground, percent herbaceous cover, percent litter, and percent shrub, and four secondary components including percent sagebrush (Artemisia spp.), percent big sagebrush (Artemisia tridentata), percent Wyoming sagebrush (Artemisia tridentata Wyomingensis), and shrub height using a regression tree. According to an independent accuracy assessment, primary component root mean square error (RMSE) values ranged from 4.90 to 10.16 for 2.4 m QuickBird, 6.01 to 15.54 for 30 m Landsat, and 6.97 to 16.14 for 56 m AWiFS. Shrub and herbaceous components outperformed the current data standard called LANDFIRE, with a shrub RMSE value of 6.04 versus 12.64 and a herbaceous component RMSE value of 12.89 versus 14.63. This approach offers new advancements in sagebrush characterization from remote sensing and provides a foundation to quantitatively monitor these components into the future.

  14. Multi-scale remote sensing sagebrush characterization with regression trees over Wyoming, USA: Laying a foundation for monitoring

    NASA Astrophysics Data System (ADS)

    Homer, Collin G.; Aldridge, Cameron L.; Meyer, Debra K.; Schell, Spencer J.

    2012-02-01

    Sagebrush ecosystems in North America have experienced extensive degradation since European settlement. Further degradation continues from exotic invasive plants, altered fire frequency, intensive grazing practices, oil and gas development, and climate change - adding urgency to the need for ecosystem-wide understanding. Remote sensing is often identified as a key information source to facilitate ecosystem-wide characterization, monitoring, and analysis; however, approaches that characterize sagebrush with sufficient and accurate local detail across large enough areas to support this paradigm are unavailable. We describe the development of a new remote sensing sagebrush characterization approach for the state of Wyoming, U.S.A. This approach integrates 2.4 m QuickBird, 30 m Landsat TM, and 56 m AWiFS imagery into the characterization of four primary continuous field components including percent bare ground, percent herbaceous cover, percent litter, and percent shrub, and four secondary components including percent sagebrush ( Artemisia spp.), percent big sagebrush ( Artemisia tridentata), percent Wyoming sagebrush ( Artemisia tridentata Wyomingensis), and shrub height using a regression tree. According to an independent accuracy assessment, primary component root mean square error (RMSE) values ranged from 4.90 to 10.16 for 2.4 m QuickBird, 6.01 to 15.54 for 30 m Landsat, and 6.97 to 16.14 for 56 m AWiFS. Shrub and herbaceous components outperformed the current data standard called LANDFIRE, with a shrub RMSE value of 6.04 versus 12.64 and a herbaceous component RMSE value of 12.89 versus 14.63. This approach offers new advancements in sagebrush characterization from remote sensing and provides a foundation to quantitatively monitor these components into the future.

  15. Synthesis and characterization of actinide nitrides

    SciTech Connect

    Jaques, Brian; Butt, Darryl P.; Marx, Brian M.; Hamdy, A.S.; Osterberg, Daniel; Balfour, Gordon

    2007-07-01

    A carbothermic reduction of the metal oxides in a hydrogen/nitrogen mixed gas stream prior to nitriding in a nitrogen gas stream was used to synthesize uranium nitride at 1500 deg. C, cerium nitride at 1400 deg. C, and dysprosium nitride at 1500 deg. C. Cerium nitride and dysprosium nitride were also synthesized via hydriding and nitriding the metal shavings at 900 deg. C and 1500 deg. C, respectively. Also, a novel ball-milling synthesis route was used to produce cerium nitride and dysprosium nitride from the metal shavings at room temperature. Dysprosium nitride was also produced by reacting the metal shavings in a high purity nitrogen gas stream at 1300 deg. C. All materials were characterized by phase analysis via X-ray diffraction. Only the high purity materials were further analyzed via chemical analysis to characterize the trace oxygen concentration. (authors)

  16. Gas-water two-phase flow characterization with Electrical Resistance Tomography and Multivariate Multiscale Entropy analysis.

    PubMed

    Tan, Chao; Zhao, Jia; Dong, Feng

    2015-03-01

    Flow behavior characterization is important to understand gas-liquid two-phase flow mechanics and further establish its description model. An Electrical Resistance Tomography (ERT) provides information regarding flow conditions at different directions where the sensing electrodes implemented. We extracted the multivariate sample entropy (MSampEn) by treating ERT data as a multivariate time series. The dynamic experimental results indicate that the MSampEn is sensitive to complexity change of flow patterns including bubbly flow, stratified flow, plug flow and slug flow. MSampEn can characterize the flow behavior at different direction of two-phase flow, and reveal the transition between flow patterns when flow velocity changes. The proposed method is effective to analyze two-phase flow pattern transition by incorporating information of different scales and different spatial directions. PMID:25304040

  17. Integrated, Multi-Scale Characterization of Imbibition and Wettability Phenomena Using Magnetic Resonance and Wide-Band Dielectric Measurements

    SciTech Connect

    Mukul M. Sharma; Steven L. Bryant; Carlos Torres-Verdin; George Hirasaki

    2007-09-30

    The petrophysical properties of rocks, particularly their relative permeability and wettability, strongly influence the efficiency and the time-scale of all hydrocarbon recovery processes. However, the quantitative relationships needed to account for the influence of wettability and pore structure on multi-phase flow are not yet available, largely due to the complexity of the phenomena controlling wettability and the difficulty of characterizing rock properties at the relevant length scales. This project brings together several advanced technologies to characterize pore structure and wettability. Grain-scale models are developed that help to better interpret the electric and dielectric response of rocks. These studies allow the computation of realistic configurations of two immiscible fluids as a function of wettability and geologic characteristics. These fluid configurations form a basis for predicting and explaining macroscopic behavior, including the relationship between relative permeability, wettability and laboratory and wireline log measurements of NMR and dielectric response. Dielectric and NMR measurements have been made show that the response of the rocks depends on the wetting and flow properties of the rock. The theoretical models can be used for a better interpretation and inversion of standard well logs to obtain accurate and reliable estimates of fluid saturation and of their producibility. The ultimate benefit of this combined theoretical/empirical approach for reservoir characterization is that rather than reproducing the behavior of any particular sample or set of samples, it can explain and predict trends in behavior that can be applied at a range of length scales, including correlation with wireline logs, seismic, and geologic units and strata. This approach can substantially enhance wireline log interpretation for reservoir characterization and provide better descriptions, at several scales, of crucial reservoir flow properties that govern oil

  18. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Chmielewski, T.; Pollard, J.

    1989-10-01

    Present studies on the electrochemical aspects of pyrite flotation in the presence of reducing agents were conducted to explain the effects observed during flotation of the separated organic and mineral-rich fractions of coal independently when sodium dithionite was used as an additive during and after grinding. In addition, the electrochemical phenomena occurring on the surface of pyrites of different origin was studied to aid in explaining the differences observed in the flotation of various coal-derived pyrite samples. Potentiometric and voltametric measurements have been conducted on electrodes prepared from natural pyrite samples of mineral and coal origin. Voltametric curves recorded on FeS{sub 2} electrodes indicate the presence of elemental sulfur, iron-oxy, and iron-hydroxy compounds, even on the freshly prepared surfaces. Comparison of voltametric curves with results of potentiometric measurements show that in the presence of dithionite several electrochemical processes are expected to take place on the pyrite surface. Voltametric curves recorded in solutions of different pH with and without sodium dithionite demonstrate that pyrite is a very good electrocatalyst in the anodic oxidation of dithionite. 13 refs., 12 figs.

  19. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Burkhart, L.; Tampy, G.; Chmielewski, T.; Pollard, J.

    1989-10-01

    In order to assess the effect of pretreatment with sodium dithionite on physical cleaning of coal, flotation tests were conducted on organic-rich and mineral-rich fractions of Upper Freeport, Lower Kittanning, and Illinois No. 6 run-of-mine coals. The organic- and mineral-rich fractions were previously obtained by gravity separation. Flotation rate constants (which are one measure of the floatability of particles) were determined from collectorless flotation of the organic-rich fraction of Illinois No. 6 coal and compared to the concentration of sodium dithionite (a reducing agent) in the flotation medium. The rate constants were also evaluated for tests conducted with solutions of sodium dithionite that were completely oxidized by exposure to atmospheric oxygen. Additional flotation tests were also conducted with the same fractions of the coals using kerosene as a collector. The responses of the different coals varied but followed a similar pattern. Preliminary flotation tests were also conducted with pyrite samples from coal and from ore sources. The results showed that flotation behavior can vary significantly for pyrites from different sources. 7 refs., 4 figs.

  20. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Burkhart, L.; Tampy, G.; Pollard, J.

    1989-07-01

    The results of using a reducing agent (sodium dithionite) as an additive during the grinding and beneficiation of an Illinois No. 6 run-of-mine coal are shown. Earlier work had indicated that with use of the additive improved sulfur removal from Upper Freeport and Lower Kittanning run-of-mine coals could be achieved using physical beneficiation techniques such as oil agglomeration and microbubble flotation. For the best results with the earlier coal samples, it was seen that the additive had to be present both during grinding and separation for Upper Freeport coal, and during grinding only for Lower Kittanning coal. For the Illinois No. 6 coal used in this study, the results are sensitive not only to the stage in which the additive is added, but also to the type of separation technique used. It is evident that the additive does cause a depression of sulfide minerals, and thus improves sulfur removal, both during microbubble flotation and oil agglomeration. However, although the additive has no detrimental effects on the recovery of clean coal or ash reduction during oil agglomeration, significant decreases in coal recovery and ash reduction are observed if the additive is used in microbubble flotation. The possible reasons for this difference are discussed. 7 refs., 3 figs., 2 tabs.

  1. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Burkhart, L.; Tampy, G.; Pollard, J.; Xu, Y.

    1989-01-01

    Beneficiation tests were conducted with Lower Kittanning run-of-mine coal using sodium dithionite, a reducing agent, as an additive during grinding and subsequent beneficiation to assess the effect on sulfur reduction. It was found that the sulfur reductions obtained by using the reducing agent as an additive were significantly better than sulfur reductions with no additive. It was also found that for the best results, the additive had to be added during the grinding stage. However, for this coal, the best results were not obtained when the reducing agent was present both during grinding and beneficiation, as was found in earlier tests with Upper Freeport coal. For the Lower Kittanning coal, the best results were obtained when the additive was added during grinding only. The increased depression of sulfur was not accompanied by a decreased recovery of the organic fraction of the coal. This demonstrates that the most appropriate treatment to maximize sulfur reduction can vary from coal to coal. Flotation rate constants, which give an indication of the floatability of particles, were also measured for this coal as a function of additive concentration. As in the case of Upper Freeport coal, the floatability of the organic fractions of Lower Kittanning coal were found to sharply increase when the additive concentration was increased beyond a critical concentration of about 0.06M. 3 refs., 3 figs., 2 tabs.

  2. Increasing biochar surface area: Optimization of ball milling parameters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar produced from corn stover is a renewable, plentiful source of carbon that is a potential substitute for carbon black as rubber composite filler and also as binder/filter media for water or beverage purification applications. However, to be successful in these applications, the surface area o...

  3. Multi-Scale Characterization of Lyotropic Liquid Crystals Using 2H and Diffusion MRI with Spatial Resolution in Three Dimensions

    PubMed Central

    Bernin, Diana; Koch, Vanessa; Nydén, Magnus; Topgaard, Daniel

    2014-01-01

    The ability of lyotropic liquid crystals to form intricate structures on a range of length scales can be utilized for the synthesis of structurally complex inorganic materials, as well as in devices for controlled drug delivery. Here we employ magnetic resonance imaging (MRI) for non-invasive characterization of nano-, micro-, and millimeter scale structures in liquid crystals. The structure is mirrored in the translational and rotational motion of the water, which we assess by measuring spatially resolved self-diffusion tensors and spectra. Our approach differs from previous works in that the MRI parameters are mapped with spatial resolution in all three dimensions, thus allowing for detailed studies of liquid crystals with complex millimeter-scale morphologies that are stable on the measurement time-scale of 10 hours. The data conveys information on the nanometer-scale structure of the liquid crystalline phase, while the combination of diffusion and data permits an estimate of the orientational distribution of micrometer-scale anisotropic domains. We study lamellar phases consisting of the nonionic surfactant C10E3 in O, and follow their structural equilibration after a temperature jump and the cessation of shear. Our experimental approach may be useful for detailed characterization of liquid crystalline materials with structures on multiple length scales, as well as for studying the mechanisms of phase transitions. PMID:24905818

  4. Environmental Assessment and Monitoring with ICAMS (Image Characterization and Modeling System) Using Multiscale Remote-Sensing Data

    NASA Technical Reports Server (NTRS)

    Lam, N.; Qiu, H.-I.; Quattrochi, Dale A.; Zhao, Wei

    1997-01-01

    With the rapid increase in spatial data, especially in the NASA-EOS (Earth Observing System) era, it is necessary to develop efficient and innovative tools to handle and analyze these data so that environmental conditions can be assessed and monitored. A main difficulty facing geographers and environmental scientists in environmental assessment and measurement is that spatial analytical tools are not easily accessible. We have recently developed a remote sensing/GIS software module called Image Characterization and Modeling System (ICAMS) to provide specialized spatial analytical tools for the measurement and characterization of satellite and other forms of spatial data. ICAMS runs on both the Intergraph-MGE and Arc/info UNIX and Windows-NT platforms. The main techniques in ICAMS include fractal measurement methods, variogram analysis, spatial autocorrelation statistics, textural measures, aggregation techniques, normalized difference vegetation index (NDVI), and delineation of land/water and vegetated/non-vegetated boundaries. In this paper, we demonstrate the main applications of ICAMS on the Intergraph-MGE platform using Landsat Thematic Mapper images from the city of Lake Charles, Louisiana. While the utilities of ICAMS' spatial measurement methods (e.g., fractal indices) in assessing environmental conditions remain to be researched, making the software available to a wider scientific community can permit the techniques in ICAMS to be evaluated and used for a diversity of applications. The findings from these various studies should lead to improved algorithms and more reliable models for environmental assessment and monitoring.

  5. Corrosion chemistry closing comments: opportunities in corrosion science facilitated by operando experimental characterization combined with multi-scale computational modelling.

    PubMed

    Scully, John R

    2015-01-01

    Recent advances in characterization tools, computational capabilities, and theories have created opportunities for advancement in understanding of solid-fluid interfaces at the nanoscale in corroding metallic systems. The Faraday Discussion on Corrosion Chemistry in 2015 highlighted some of the current needs, gaps and opportunities in corrosion science. Themes were organized into several hierarchical categories that provide an organizational framework for corrosion. Opportunities to develop fundamental physical and chemical data which will enable further progress in thermodynamic and kinetic modelling of corrosion were discussed. These will enable new and better understanding of unit processes that govern corrosion at the nanoscale. Additional topics discussed included scales, films and oxides, fluid-surface and molecular-surface interactions, selected topics in corrosion science and engineering as well as corrosion control. Corrosion science and engineering topics included complex alloy dissolution, local corrosion, and modelling of specific corrosion processes that are made up of collections of temporally and spatially varying unit processes such as oxidation, ion transport, and competitive adsorption. Corrosion control and mitigation topics covered some new insights on coatings and inhibitors. Further advances in operando or in situ experimental characterization strategies at the nanoscale combined with computational modelling will enhance progress in the field, especially if coupling across length and time scales can be achieved incorporating the various phenomena encountered in corrosion. Readers are encouraged to not only to use this ad hoc organizational scheme to guide their immersion into the current opportunities in corrosion chemistry, but also to find value in the information presented in their own ways. PMID:26114392

  6. Multi-scale field characterization, data assimilation, and 2-D model development for a complex river confluence

    NASA Astrophysics Data System (ADS)

    Pai, H.; Fisher, J. C.; Villamizar, S. R.; Butler, C. A.; Kaiser, W.; Harmon, T. C.

    2009-12-01

    Questions pertaining to stream restoration ecology, environmental flows, and hydrology may require higher resolution observation and simulation capabilities than are typical of hydrologic investigations. Multi-dimensional models can provide more insight into the coupled biogeochemical processes needed to fully understand these systems. Of course, such models require a large amount of data relative to more simplistic models to accurately represent real conditions. This work summarizes an end-to-end exercise spanning from data collection to model calibration at the shallow confluence of the San Joaquin River (SJR) and Merced River in Central California. A raster pattern of point velocity measurements was collected using an automated device known as Rapidly Deployable Networked Infomechanical System (NIMSRD) transporting an acoustic Doppler velocimeter (ADV) over river cross sections, and flow was then calculated using the midsection method. Flow estimates were within 12% of those from a nearby USGS gaging station. Bathymetric data were collected by surveying depths for shallow stretches and by echosounding for deeper stretches, and then smoothed using multilevel B-spline interpolation (MBI). The resulting flow, bathymetry, and water surface elevation (WSE) datasets were used as boundary conditions in a commercially available modeling software package, Surface water Modeling Systems (SMS), comparing two different finite element modeling modules: FESWMS and RMA2. Modeled flow and WSEs were compared to observed values to determine model performance and evaluated for three cases with differing mesh element sizes, model type, and bathymetry interpolation method (MBI or inverse distance). Simulations indicated that for similar numerical discretization, FESWMS outperformed RMA2, with finer mesh size and interpolated bathymetry leading to better model performance in both cases. Overall, the integrated field characterization and modeling approach demonstrates the feasibility

  7. Experimental characterization of multiscale and multifield turbulence as a critical gradient threshold is surpassed in the DIII-D tokamaka)

    NASA Astrophysics Data System (ADS)

    Hillesheim, J. C.; DeBoo, J. C.; Peebles, W. A.; Carter, T. A.; Wang, G.; Rhodes, T. L.; Schmitz, L.; McKee, G. R.; Yan, Z.; Staebler, G. M.; Burrell, K. H.; Doyle, E. J.; Holland, C.; Petty, C. C.; Smith, S. P.; White, A. E.; Zeng, L.

    2013-05-01

    A critical gradient for long wavelength (kθρs≲0.4) electron temperature fluctuations has been observed in an experiment in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)], where below a threshold value of LTe-1=|∇Te|/Te electron temperature fluctuations are constant and above they steadily increase. Above the critical gradient, the electron heat flux inferred by power balance also increases rapidly. Critical gradients are a predicted attribute of turbulence arising from linear instabilities and are thought to be related to transport stiffness. The presented results are the first direct, systematic demonstration of critical gradient behavior in turbulence measurements in a tokamak. The experiment was performed by changing the deposition location of electron cyclotron heating shot-to-shot to locally scan LTe-1 at r/a = 0.6 in L-mode plasmas; rotation was also varied by changing the momentum input from neutral beam injection. Temperature fluctuations were measured with a correlation electron cyclotron emission (CECE) radiometry system. In addition to the CECE measurements, an array of turbulence measurements were acquired to characterize fluctuations in multiple fields and at multiple scales as LTe-1 and rotation were modified: long wavelength (kθρs≲0.5) density fluctuations were acquired with beam emission spectroscopy, the phase angle between electron temperature and density fluctuations was measured by coupling the CECE system and a reflectometer, intermediate scale (kθρs˜0.8) density fluctuations were measured with a Doppler backscattering (DBS) system, and low frequency flows were also measured with DBS. The accumulated measurements and trends constrain identification of the instability responsible for the observed critical gradient to the ∇Te-driven trapped electron mode.

  8. Characterization of Multi-Scale Atmospheric Conditions Associated with Extreme Precipitation in the Transverse Ranges of Southern California

    NASA Astrophysics Data System (ADS)

    Oakley, N.; Kaplan, M.; Ralph, F. M.

    2015-12-01

    The east-west oriented Transverse Ranges of Southern California have historically experienced shallow landslides and debris flows that threaten life and property. Steep topography, soil composition, and frequent wildfires make this area susceptible to mass wasting. Extreme rainfall often acts as a trigger for these events. This work characterizes atmospheric conditions at multiple scales during extreme (>99th percentile) 1-day precipitation events in the major sub-ranges of the Transverse Ranges. Totals from these 1-day events generally exceed the established sub-daily intensity-duration thresholds for shallow landslides and debris flows in this region. Daily extreme precipitation values are derived from both gridded and station-based datasets over the period 1958-2014. For each major sub-range, extreme events are clustered by atmospheric feature and direction of moisture transport. A composite analysis of synoptic conditions is produced for each cluster to create a conceptual model of atmospheric conditions favoring extreme precipitation. The vertical structure of the atmosphere during these extreme events is also examined using observed and modeled soundings. Preliminary results show two atmospheric features to be of importance: 1) closed and cutoff low-pressure systems, areas of counter-clockwise circulation that can produce southerly flow orthogonal to the Transverse Range ridge axes; and 2) atmospheric rivers that transport large quantities of water vapor into the region. In some cases, the closed lows and atmospheric rivers work in concert with each other to produce extreme precipitation. Additionally, there is a notable east-west dipole of precipitation totals during some extreme events between the San Gabriel and Santa Ynez Mountains where extreme values are observed in one range and not the other. The cause of this relationship is explored. The results of this work can help forecasters and emergency responders determine the likelihood that an event will

  9. Development of a multi-scale and multi-modality imaging system to characterize tumours and their microenvironment in vivo

    NASA Astrophysics Data System (ADS)

    Rouffiac, Valérie; Ser-Leroux, Karine; Dugon, Emilie; Leguerney, Ingrid; Polrot, Mélanie; Robin, Sandra; Salomé-Desnoulez, Sophie; Ginefri, Jean-Christophe; Sebrié, Catherine; Laplace-Builhé, Corinne

    2015-03-01

    In vivo high-resolution imaging of tumor development is possible through dorsal skinfold chamber implantable on mice model. However, current intravital imaging systems are weakly tolerated along time by mice and do not allow multimodality imaging. Our project aims to develop a new chamber for: 1- long-term micro/macroscopic visualization of tumor (vascular and cellular compartments) and tissue microenvironment; and 2- multimodality imaging (photonic, MRI and sonography). Our new experimental device was patented in March 2014 and was primarily assessed on 75 mouse engrafted with 4T1-Luc tumor cell line, and validated in confocal and multiphoton imaging after staining the mice vasculature using Dextran 155KDa-TRITC or Dextran 2000kDa-FITC. Simultaneously, a universal stage was designed for optimal removal of respiratory and cardiac artifacts during microscopy assays. Experimental results from optical, ultrasound (Bmode and pulse subtraction mode) and MRI imaging (anatomic sequences) showed that our patented design, unlike commercial devices, improves longitudinal monitoring over several weeks (35 days on average against 12 for the commercial chamber) and allows for a better characterization of the early and late tissue alterations due to tumour development. We also demonstrated the compatibility for multimodality imaging and the increase of mice survival was by a factor of 2.9, with our new skinfold chamber. Current developments include: 1- defining new procedures for multi-labelling of cells and tissue (screening of fluorescent molecules and imaging protocols); 2- developing ultrasound and MRI imaging procedures with specific probes; 3- correlating optical/ultrasound/MRI data for a complete mapping of tumour development and microenvironment.

  10. Multi-scale analysis in carbonates by X-ray microtomography: Characterization of the porosity and pore size distribution

    NASA Astrophysics Data System (ADS)

    Fernandes, Jaquiel S.; Nagata, Rodrigo; Moreira, Anderson C.; Fernandes, Celso P.; Appoloni, Carlos R.

    2013-05-01

    The porous systems of reservoir rocks present a complex geometry, involving aspects of shape of pores (morphology) and connectivity between the pores (topology). The macroscopic physical properties of these materials are strongly dependent of their microstructures. Based on these aspects, the present study has as main objective the characterization of the porous system geometry and computational determination of petrophysics properties of carbonate reservoir rocks through the X-ray microtomography methodology. Samples were microtomographed with the microtomographs Skyscan model 1172, installed at the PETROBRAS Research and Development Center (CENPES), Rio de Janeiro-RJ, Brazil and model 1173, installed at Sedimentary Geology Laboratory (LAGESD) in the Federal University of Rio de Janeiro (UFRJ). Two samples of carbonates were measured, Travertine and Dolomite, with spatial resolutions of 7 μm and 9.8 μm and 1.3 μm, 7 μm and 17 μm, respectively for the travertine and dolomite. With the data collected in the acquisitions, 900 transversal sections were reconstructed for each one of the referred resolutions. For the sample of dolomite, the average porosity found was 21.64%, 20.92% and 15.97% for resolutions of 1.3 μm, 7 μm and 17 μm, respectively. For the sample of travertine, the average porosity was 7.80 % and 7.52 % for resolutions of 7 μm and 9.8 μm, respectively. For the sample of dolomite, the pore size distribution showed that 50 % of the porous phase has pores with radius up to 37.6 μm, 84.6 μm and 84.4 μm, for the spatial resolutions of 1.3 μm, 7 μm and 17 μm, respectively. For the sample of travertine, 50 % of the pores have radius up to 148.1 μm and 158.1 μm, for the spatial resolutions of 7 μm and 9.8 μm.

  11. Experimental characterization of multiscale and multifield turbulence as a critical gradient threshold is surpassed in the DIII-D tokamak

    SciTech Connect

    Hillesheim, J. C.; Peebles, W. A.; Carter, T. A.; Wang, G.; Rhodes, T. L.; Schmitz, L.; Doyle, E. J.; Zeng, L.; DeBoo, J. C.; Staebler, G. M.; Burrell, K. H.; Petty, C. C.; Smith, S. P.; McKee, G. R.; Yan, Z.; Holland, C.; White, A. E.

    2013-05-15

    A critical gradient for long wavelength (k{sub θ}ρ{sub s}≲0.4) electron temperature fluctuations has been observed in an experiment in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)], where below a threshold value of L{sub T{sub e}{sup −1}}=|∇T{sub e}|/T{sub e} electron temperature fluctuations are constant and above they steadily increase. Above the critical gradient, the electron heat flux inferred by power balance also increases rapidly. Critical gradients are a predicted attribute of turbulence arising from linear instabilities and are thought to be related to transport stiffness. The presented results are the first direct, systematic demonstration of critical gradient behavior in turbulence measurements in a tokamak. The experiment was performed by changing the deposition location of electron cyclotron heating shot-to-shot to locally scan L{sub T{sub e}{sup −1}} at r/a = 0.6 in L-mode plasmas; rotation was also varied by changing the momentum input from neutral beam injection. Temperature fluctuations were measured with a correlation electron cyclotron emission (CECE) radiometry system. In addition to the CECE measurements, an array of turbulence measurements were acquired to characterize fluctuations in multiple fields and at multiple scales as L{sub T{sub e}{sup −1}} and rotation were modified: long wavelength (k{sub θ}ρ{sub s}≲0.5) density fluctuations were acquired with beam emission spectroscopy, the phase angle between electron temperature and density fluctuations was measured by coupling the CECE system and a reflectometer, intermediate scale (k{sub θ}ρ{sub s}∼0.8) density fluctuations were measured with a Doppler backscattering (DBS) system, and low frequency flows were also measured with DBS. The accumulated measurements and trends constrain identification of the instability responsible for the observed critical gradient to the ∇T{sub e}-driven trapped electron mode.

  12. Fabrication and characterization of hexagonal boron nitride powder by spray drying and calcining-nitriding technology

    SciTech Connect

    Shi Xiaoliang Wang Sheng; Yang Hua; Duan Xinglong; Dong Xuebin

    2008-09-15

    Hexagonal boron nitride (hBN) powder was fabricated prepared by the spray drying and calcining-nitriding technology. The effects of nitrided temperature on the phases, morphology and particle size distribution of hBN powder, were investigated. The synthesized powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transformed infrared spectrum, ultraviolet-visible (UV-vis) spectrum and photoluminescence (PL) spectrum. UV-vis spectrum revealed that the product had one obvious band gap (4.7 eV) and PL spectrum showed that it had a visible emission at 457 nm ({lambda}{sub ex}=230 nm). FESEM image indicated that the particle size of the synthesized hBN was mainly in the range of 0.5-1.5 {mu}m in diameter, and 50-150 nm in thickness. The high-energy ball-milling process following 900 deg. C calcining process was very helpful to obtain fully crystallized hBN at lower temperature. - Graphical abstract: hBN powder was fabricated prepared by spray drying and calcining-nitriding technology. The results indicated that spray drying and calcining-nitriding technology assisted with high-energy ball-milling process following calcined process was a hopeful way to manufacture hBN powder with high crystallinity in industrial scale.

  13. Facile synthesis and characterization of hexagonal NbSe{sub 2} nanoplates

    SciTech Connect

    Zhang, Xianghua; Zhang, Du; Tang, Hua; Ji, Xiaorui; Zhang, Yi; Tang, Guogang; Li, Changsheng

    2014-05-01

    Graphical abstract: - Highlights: • Uniform hexagonal NbSe{sub 2} nanoplates were prepared by a simple solid state reaction. • The possible formation mechanism of the NbSe{sub 2} nanoplates was discussed. • The formation of NbSe{sub 2} nanoplates undergoes a series of phase transition. - Abstract: The NbSe{sub 2} nanoplates with hexagonal morphology have been successfully prepared by a facile, environmentally friendly reaction in closed reactor at moderate temperature. The thermal (750 °C) solid-state reaction between the ball-milled mixture of micro-sized Nb and Se yielded a high yield of NbSe{sub 2} nanoplates. The as-prepared products were characterized by XRD, EDS, and SEM. The results showed that the as-prepared products were hexagonal phase NbSe{sub 2} nanoplates with uniform sizes and the formation of NbSe{sub 2} nanoplates underwent a series of phase transition. On the basis of experimental results obtained at different temperatures, a reasonable reaction process and a formation mechanism were proposed. Moreover, the ball milling time played a crucial role in acquiring the homogeneous distribution nanoplates.

  14. Modeling folding related multi-scale deformation of sedimentary rock using ALSM and fracture characterization at Raplee Ridge, UT

    NASA Astrophysics Data System (ADS)

    Mynatt, I.; Hilley, G. E.; Pollard, D. D.

    2006-12-01

    Understanding and predicting the characteristics of folding induced fracturing is an important and intriguing structural problem. Folded sequences of sedimentary rock at depth are common traps for hydrocarbons and water and fractures can strongly effect (both positively and negatively) this trapping capability. For these reasons fold-fracture relationships are well studied, but due to the complex interactions between the remote tectonic stress, rheologic properties, underlying fault geometry and slip, and pre-existing fractures, fracture characteristics can vary greatly from fold to fold. Additionally, examination of the relationships between fundamental characteristics such as fold geometry and fracture density are difficult even in thoroughly studied producing fields as measurements of fold shape are hampered by the low resolution of seismic surveying and measurements of fractures are limited to sparse well-bore locations. Due to the complexity of the system, the limitations of available data and small number of detailed case studies, prediction of fracture characteristics, e.g. the distribution of fracture density, are often difficult to make for a particular fold. We suggest a combination of mechanical and numerical modeling and analysis combined with detailed field mapping can lead to important insights into fold-fracture relationships. We develop methods to quantify both fold geometry and fracture characteristics, and summarize their relationships for an exhumed analogue reservoir case study. The field area is Raplee Monocline, a Laramide aged, N-S oriented, ~14-km long fold exposed in the Monument Upwarp of south-eastern Utah and part of the larger Colorado Plateau geologic province. The investigation involves three distinct parts: 1) Field based characterization and mapping of the fractures on and near the fold; 2) Development of accurate models of the fold geometry using high resolution data including ~3.5x107 x, y, z topographic points collected using

  15. Multiscale Cancer Modeling

    PubMed Central

    Macklin, Paul; Cristini, Vittorio

    2013-01-01

    Simulating cancer behavior across multiple biological scales in space and time, i.e., multiscale cancer modeling, is increasingly being recognized as a powerful tool to refine hypotheses, focus experiments, and enable more accurate predictions. A growing number of examples illustrate the value of this approach in providing quantitative insight on the initiation, progression, and treatment of cancer. In this review, we introduce the most recent and important multiscale cancer modeling works that have successfully established a mechanistic link between different biological scales. Biophysical, biochemical, and biomechanical factors are considered in these models. We also discuss innovative, cutting-edge modeling methods that are moving predictive multiscale cancer modeling toward clinical application. Furthermore, because the development of multiscale cancer models requires a new level of collaboration among scientists from a variety of fields such as biology, medicine, physics, mathematics, engineering, and computer science, an innovative Web-based infrastructure is needed to support this growing community. PMID:21529163

  16. An Analysis Platform for Multiscale Hydrogeologic Modeling with Emphasis on Hybrid Multiscale Methods

    SciTech Connect

    Scheibe, Timothy D.; Murphy, Ellyn M.; Chen, Xingyuan; Rice, Amy K.; Carroll, Kenneth C.; Palmer, Bruce J.; Tartakovsky, Alexandre M.; Battiato, Ilenia; Wood, Brian D.

    2015-01-01

    One of the most significant challenges facing hydrogeologic modelers is the disparity between those spatial and temporal scales at which fundamental flow, transport and reaction processes can best be understood and quantified (e.g., microscopic to pore scales, seconds to days) and those at which practical model predictions are needed (e.g., plume to aquifer scales, years to centuries). While the multiscale nature of hydrogeologic problems is widely recognized, technological limitations in computational and characterization restrict most practical modeling efforts to fairly coarse representations of heterogeneous properties and processes. For some modern problems, the necessary level of simplification is such that model parameters may lose physical meaning and model predictive ability is questionable for any conditions other than those to which the model was calibrated. Recently, there has been broad interest across a wide range of scientific and engineering disciplines in simulation approaches that more rigorously account for the multiscale nature of systems of interest. In this paper, we review a number of such approaches and propose a classification scheme for defining different types of multiscale simulation methods and those classes of problems to which they are most applicable. Our classification scheme is presented in terms of a flow chart (Multiscale Analysis Platform or MAP), and defines several different motifs of multiscale simulation. Within each motif, the member methods are reviewed and example applications are discussed. We focus attention on hybrid multiscale methods, in which two or more models with different physics described at fundamentally different scales are directly coupled within a single simulation. Very recently these methods have begun to be applied to groundwater flow and transport simulations, and we discuss these applications in the context of our classification scheme. As computational and characterization capabilities continue to

  17. Community Multiscale Air Quality Model

    EPA Science Inventory

    The U.S. EPA developed the Community Multiscale Air Quality (CMAQ) system to apply a “one atmosphere” multiscale and multi-pollutant modeling approach based mainly on the “first principles” description of the atmosphere. The multiscale capability is supported by the governing di...

  18. Adaptive multiscale model reduction with Generalized Multiscale Finite Element Methods

    NASA Astrophysics Data System (ADS)

    Chung, Eric; Efendiev, Yalchin; Hou, Thomas Y.

    2016-09-01

    In this paper, we discuss a general multiscale model reduction framework based on multiscale finite element methods. We give a brief overview of related multiscale methods. Due to page limitations, the overview focuses on a few related methods and is not intended to be comprehensive. We present a general adaptive multiscale model reduction framework, the Generalized Multiscale Finite Element Method. Besides the method's basic outline, we discuss some important ingredients needed for the method's success. We also discuss several applications. The proposed method allows performing local model reduction in the presence of high contrast and no scale separation.

  19. A mathematical framework for multiscale science and engineering : the variational multiscale method and interscale transfer operators.

    SciTech Connect

    Shadid, John Nicolas; Lehoucq, Richard B.; Christon, Mark Allen; Slepoy, Alexander; Bochev, Pavel Blagoveston; Collis, Samuel Scott; Wagner, Gregory John

    2004-05-01

    Existing approaches in multiscale science and engineering have evolved from a range of ideas and solutions that are reflective of their original problem domains. As a result, research in multiscale science has followed widely diverse and disjoint paths, which presents a barrier to cross pollination of ideas and application of methods outside their application domains. The status of the research environment calls for an abstract mathematical framework that can provide a common language to formulate and analyze multiscale problems across a range of scientific and engineering disciplines. In such a framework, critical common issues arising in multiscale problems can be identified, explored and characterized in an abstract setting. This type of overarching approach would allow categorization and clarification of existing models and approximations in a landscape of seemingly disjoint, mutually exclusive and ad hoc methods. More importantly, such an approach can provide context for both the development of new techniques and their critical examination. As with any new mathematical framework, it is necessary to demonstrate its viability on problems of practical importance. At Sandia, lab-centric, prototype application problems in fluid mechanics, reacting flows, magnetohydrodynamics (MHD), shock hydrodynamics and materials science span an important subset of DOE Office of Science applications and form an ideal proving ground for new approaches in multiscale science.

  20. Engineering Digestion: Multiscale Processes of Food Digestion.

    PubMed

    Bornhorst, Gail M; Gouseti, Ourania; Wickham, Martin S J; Bakalis, Serafim

    2016-03-01

    Food digestion is a complex, multiscale process that has recently become of interest to the food industry due to the developing links between food and health or disease. Food digestion can be studied by using either in vitro or in vivo models, each having certain advantages or disadvantages. The recent interest in food digestion has resulted in a large number of studies in this area, yet few have provided an in-depth, quantitative description of digestion processes. To provide a framework to develop these quantitative comparisons, a summary is given here between digestion processes and parallel unit operations in the food and chemical industry. Characterization parameters and phenomena are suggested for each step of digestion. In addition to the quantitative characterization of digestion processes, the multiscale aspect of digestion must also be considered. In both food systems and the gastrointestinal tract, multiple length scales are involved in food breakdown, mixing, absorption. These different length scales influence digestion processes independently as well as through interrelated mechanisms. To facilitate optimized development of functional food products, a multiscale, engineering approach may be taken to describe food digestion processes. A framework for this approach is described in this review, as well as examples that demonstrate the importance of process characterization as well as the multiple, interrelated length scales in the digestion process. PMID:26799793

  1. Multiscale Representation of Genomic Signals

    PubMed Central

    Knijnenburg, Theo A.; Ramsey, Stephen A.; Berman, Benjamin P.; Kennedy, Kathleen A.; Smit, Arian F.A.; Wessels, Lodewyk F.A.; Laird, Peter W.; Aderem, Alan; Shmulevich, Ilya

    2014-01-01

    Genomic information is encoded on a wide range of distance scales, ranging from tens of base pairs to megabases. We developed a multiscale framework to analyze and visualize the information content of genomic signals. Different types of signals, such as GC content or DNA methylation, are characterized by distinct patterns of signal enrichment or depletion across scales spanning several orders of magnitude. These patterns are associated with a variety of genomic annotations, including genes, nuclear lamina associated domains, and repeat elements. By integrating the information across all scales, as compared to using any single scale, we demonstrate improved prediction of gene expression from Polymerase II chromatin immunoprecipitation sequencing (ChIP-seq) measurements and we observed that gene expression differences in colorectal cancer are not most strongly related to gene body methylation, but rather to methylation patterns that extend beyond the single-gene scale. PMID:24727652

  2. Multisensor and multiscale survey and characterization for radiometric spatial uniformity and temporal stability of Railroad Valley Playa (Nevada) test site used for optical sensor calibration

    NASA Astrophysics Data System (ADS)

    Bannari, Abdou A.; Omari, K.; Teillet, Phillipe M.; Fedosejevs, Gunar

    2004-02-01

    In this study, we analyzed for the first time the potential of Getis statistics compared to the coefficient of variation for the study of the radiometric spatial uniformity and temporal stability of the Railroad Valley Playa, Nevada (RVPN) test site. We evaluated multi-sensor and multi-scale image data acquired for the RVPN, including four SPOT HRV images acquired in 1997 and 1998, five NOAA AVHRR images acquired in 1999, and one Landsat TM image acquired in 1998. The results show the potential and the importance of the synergy generated by these two methods for analyzing the radiometric spatial uniformity and temporal stability of the RVPN site. Getis statistics provide an excellent spatial analysis of the site while the coefficient of variation provides complementary information on the temporal evolution of the site.

  3. Sample preparation for thermo-gravimetric determination and thermo-gravimetric characterization of refuse derived fuel.

    PubMed

    Robinson, T; Bronson, B; Gogolek, P; Mehrani, P

    2016-02-01

    Thermo-gravimetric analysis (TGA) is a useful method for characterizing fuels. In the past it has been applied to the study of refuse derived fuel (RDF) and related materials. However, the heterogeneity of RDF makes the preparation of small representative samples very difficult and this difficulty has limited the effectiveness of TGA for characterization of RDF. A TGA method was applied to a variety of materials prepared from a commercially available RDF using a variety of procedures. Applicability of TGA method to the determination of the renewable content of RDF was considered. Cryogenic ball milling was found to be an effective means of preparing RDF samples for TGA. When combined with an effective sample preparation, TGA could be used as an alternative method for assessing the renewable content of RDF. PMID:26611398

  4. Synthesis and characterization of barium ferrite–silica nanocomposites

    SciTech Connect

    Aguilar-González, M.A.; Mendoza-Suárez, G.; Padmasree, K.P.

    2013-10-15

    In this work, we prepared barium ferrite-silica (BaM-SiO{sub 2}) nanocomposites of different molar ratios by high-energy ball milling, followed by heat-treatment at different temperatures. The microstructure, morphology and magnetic properties were characterized for different synthesis conditions by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results indicate that 15 h of milling was enough to avoid the generation of hematite phase and to get a good dispersion of barium ferrite particles in the ceramic matrix. For milling periods beyond 15 h and heat treatment above 900 °C, the XRD patterns showed the presence of hematite phase caused by the decomposition of BaM. The agglomerate size observed through SEM analysis was around 150 nm with a good BaM dispersion into the SiO{sub 2} matrix. The highest saturation magnetization (Ms) value obtained was 43 emu/g and the corresponding coercivity (Hc) value of 3.4 kOe for the composition 60BaM-40SiO{sub 2} milled for 15 h and heat treated at 900 °C. This coercivity value is acceptable for the application in magnetic recording media. Highlights: • Barium ferrite–silica nanocomposites were prepared by high energy ball milling. • Optimal processing time is 15 h milling and heat treatment at 900 °C. • This is enough to avoid the generation of hematite phase. • Obtain good dispersion of barium ferrite particles in the ceramic matrix • Above this processing time shows the presence of increased amount of hematite.

  5. Multiscale Fluctuation Analysis Revisited

    NASA Astrophysics Data System (ADS)

    Struzik, Zbigniew R.; Kiyono, Ken; Yamamoto, Yoshiharu

    2007-07-01

    Ubiquitous non-Gaussianity of the probability density of (time-series) fluctuations in many real world phenomena has been known and modelled extensively in recent years. Similarly, the analysis of (multi)scaling properties of (fluctuations in) complex systems has become a standard way of addressing unknown complexity. Yet the combined analysis and modelling of multiscale behaviour of probability density — multiscale PDF analysis — has only recently been proposed for the analysis of time series arising in complex systems, such as the cardiac neuro-regulatory system, financial markets or hydrodynamic turbulence. This relatively new technique has helped significantly to expand the previously obtained insights into the phenomena addressed. In particular, it has helped to identify a novel class of scale invariant behaviour of the multiscale PDF in healthy heart rate regulation during daily activity and in a market system undergoing crash dynamics. This kind of invariance reflects invariance of the system under renormalisation and resembles behaviour at criticality of a system undergoing continuous phase transition — indeed in both phenomena, such phase transition behaviour has been revealed. While the precise mechanism underlying invariance of the PDF under system renormalisation of both systems discussed is not to date understood, there is an intimate link between the non-Gaussian PDF characteristics and the persistent invariant correlation structure emerging between fluctuations across scale and time.

  6. Multiscale Biomechanics of Tomato Fruits: A Review.

    PubMed

    Li, Zhiguo; Thomas, Colin

    2016-05-18

    Bruising and other mechanical damage to fruit caused by external forces during and postharvesting is manifested at the macroscale but is ultimately the result of failure of cells at the microscale. However, fruits have internal structures and cells from different tissue types react differently to application of an external force. Not much is known about the effects of such forces on single cells within tissues and one reason for this is the lack of multiscale models linking macro- (organ or whole fruit), meso- (tissue), and micro- (cell) mechanics. This review concerns tomato fruits specifically as this is an important crop and is an excellent exemplar of past and proposed research in this field. The first consideration is the multiscale anatomy of tomato fruits that provides the basis for mechanical modeling. The literature on experimental methods for studying multiscale mechanics of fruit is then reviewed, as are recent results from using those methods. Finally, future research directions are discussed, in particular the combination of work over all scales. It is clear that a bottom-up approach incorporating single-cell mechanics in finite element models of whole fruit assumed to have internal structures is a promising way forward for tomato fruits but further method developments may be needed for these and other fruits and vegetables, in particular recovery of representative single cells from tissues for mechanical characterization. PMID:25674836

  7. Multiscale Macromolecular Simulation: Role of Evolving Ensembles

    PubMed Central

    Singharoy, A.; Joshi, H.; Ortoleva, P.J.

    2013-01-01

    Multiscale analysis provides an algorithm for the efficient simulation of macromolecular assemblies. This algorithm involves the coevolution of a quasiequilibrium probability density of atomic configurations and the Langevin dynamics of spatial coarse-grained variables denoted order parameters (OPs) characterizing nanoscale system features. In practice, implementation of the probability density involves the generation of constant OP ensembles of atomic configurations. Such ensembles are used to construct thermal forces and diffusion factors that mediate the stochastic OP dynamics. Generation of all-atom ensembles at every Langevin timestep is computationally expensive. Here, multiscale computation for macromolecular systems is made more efficient by a method that self-consistently folds in ensembles of all-atom configurations constructed in an earlier step, history, of the Langevin evolution. This procedure accounts for the temporal evolution of these ensembles, accurately providing thermal forces and diffusions. It is shown that efficiency and accuracy of the OP-based simulations is increased via the integration of this historical information. Accuracy improves with the square root of the number of historical timesteps included in the calculation. As a result, CPU usage can be decreased by a factor of 3-8 without loss of accuracy. The algorithm is implemented into our existing force-field based multiscale simulation platform and demonstrated via the structural dynamics of viral capsomers. PMID:22978601

  8. Multiscale macromolecular simulation: role of evolving ensembles.

    PubMed

    Singharoy, A; Joshi, H; Ortoleva, P J

    2012-10-22

    Multiscale analysis provides an algorithm for the efficient simulation of macromolecular assemblies. This algorithm involves the coevolution of a quasiequilibrium probability density of atomic configurations and the Langevin dynamics of spatial coarse-grained variables denoted order parameters (OPs) characterizing nanoscale system features. In practice, implementation of the probability density involves the generation of constant OP ensembles of atomic configurations. Such ensembles are used to construct thermal forces and diffusion factors that mediate the stochastic OP dynamics. Generation of all-atom ensembles at every Langevin time step is computationally expensive. Here, multiscale computation for macromolecular systems is made more efficient by a method that self-consistently folds in ensembles of all-atom configurations constructed in an earlier step, history, of the Langevin evolution. This procedure accounts for the temporal evolution of these ensembles, accurately providing thermal forces and diffusions. It is shown that efficiency and accuracy of the OP-based simulations is increased via the integration of this historical information. Accuracy improves with the square root of the number of historical timesteps included in the calculation. As a result, CPU usage can be decreased by a factor of 3-8 without loss of accuracy. The algorithm is implemented into our existing force-field based multiscale simulation platform and demonstrated via the structural dynamics of viral capsomers. PMID:22978601

  9. Multiscale modeling with smoothed dissipative particle dynamics.

    PubMed

    Kulkarni, Pandurang M; Fu, Chia-Chun; Shell, M Scott; Leal, L Gary

    2013-06-21

    In this work, we consider two issues related to the use of Smoothed Dissipative Particle Dynamics (SDPD) as an intermediate mesoscale model in a multiscale scheme for solution of flow problems when there are local parts of a macroscopic domain that require molecular resolution. The first is to demonstrate that SDPD with different levels of resolution can accurately represent the fluid properties from the continuum scale all the way to the molecular scale. Specifically, while the thermodynamic quantities such as temperature, pressure, and average density remain scale-invariant, we demonstrate that the dynamic properties are quantitatively consistent with an all-atom Lennard-Jones reference system when the SDPD resolution approaches the atomistic scale. This supports the idea that SDPD can serve as a natural bridge between molecular and continuum descriptions. In the second part, a simple multiscale methodology is proposed within the SDPD framework that allows several levels of resolution within a single domain. Each particle is characterized by a unique physical length scale called the smoothing length, which is inversely related to the local number density and can change on-the-fly. This multiscale methodology is shown to accurately reproduce fluid properties for the simple problem of steady and transient shear flow. PMID:23802949

  10. Microwave assisted synthesis and characterization of barium titanate nanoparticles for multi layered ceramic capacitor applications.

    PubMed

    Thirumalai, Sundararajan; Shanmugavel, Balasivanandha Prabu

    2011-01-01

    Barium titanate is a common ferroelectric electro-ceramic material having high dielectric constant, with photorefractive effect and piezoelectric properties. In this research work, nano-scale barium titanate powders were synthesized by microwave assisted mechano-chemical route. Suitable precursors were ball milled for 20 hours. TGA studies were performed to study the thermal stability of the powders. The powders were characterized by XRD, SEM and EDX Analysis. Microwave and Conventional heating were performed at 1000 degrees C. The overall heating schedule was reduced by 8 hours in microwave heating thereby reducing the energy and time requirement. The nano-scale, impurity-free and defect-free microstructure was clearly evident from the SEM micrograph and EDX patterns. LCR meter was used to measure the dielectric constant and dielectric loss values at various frequencies. Microwave heated powders showed superior dielectric constant value with low dielectric loss which is highly essential for the fabrication of Multi Layered Ceramic Capacitors. PMID:24427875

  11. Multiscale Simulation of Microbe Structure and Dynamics

    PubMed Central

    Joshi, Harshad; Singharoy, Abhishek; Sereda, Yuriy V.; Cheluvaraja, Srinath C.; Ortoleva, Peter J.

    2012-01-01

    A multiscale mathematical and computational approach is developed that captures the hierarchical organization of a microbe. It is found that a natural perspective for understanding a microbe is in terms of a hierarchy of variables at various levels of resolution. This hierarchy starts with the N -atom description and terminates with order parameters characterizing a whole microbe. This conceptual framework is used to guide the analysis of the Liouville equation for the probability density of the positions and momenta of the N atoms constituting the microbe and its environment. Using multiscale mathematical techniques, we derive equations for the co-evolution of the order parameters and the probability density of the N-atom state. This approach yields a rigorous way to transfer information between variables on different space-time scales. It elucidates the interplay between equilibrium and far-from-equilibrium processes underlying microbial behavior. It also provides framework for using coarse-grained nanocharacterization data to guide microbial simulation. It enables a methodical search for free-energy minimizing structures, many of which are typically supported by the set of macromolecules and membranes constituting a given microbe. This suite of capabilities provides a natural framework for arriving at a fundamental understanding of microbial behavior, the analysis of nanocharacterization data, and the computer-aided design of nanostructures for biotechnical and medical purposes. Selected features of the methodology are demonstrated using our multiscale bionanosystem simulator DeductiveMultiscaleSimulator. Systems used to demonstrate the approach are structural transitions in the cowpea chlorotic mosaic virus, RNA of satellite tobacco mosaic virus, virus-like particles related to human papillomavirus, and iron-binding protein lactoferrin. PMID:21802438

  12. Multi-scale petrophysical and geomechanical characterization of full core from the Groningen Field to understand mechanical stratigraphy and compaction behavior

    NASA Astrophysics Data System (ADS)

    van Eijs, Rob; Hol, Sander; Marcelis, Fons; Ishmukhametova, Gulfiia; van der Linden, Arjan; Zuiderwijk, Pedro; Makurat, Axel

    2016-04-01

    The Groningen gas field in The Netherlands is one of the largest onshore gas reserves known. Advancing production from the field has resulted in field-scale deformation with surface subsidence and accompanied local seismicity. Part of the deformation is associated with compaction of the Permian reservoir. While depletion-induced reservoir compaction is expected to be controlled locally by grain-scale physical mechanisms such as sub-critical cracking or particle re-arrangement and intergranular pressure solution creep, understanding of the intra-reservoir variability of these mechanisms is still limited, though crucial for predicting the coupling between production, rock deformation, and surface effects. To aid an improved understanding of fundamental processes and scaling effects, approximately 200 meters of core over the reservoir section was taken from a well in the Groningen Field, drilled in July 2015 close to the village of Zeerijp. Using this material, we have performed detailed laboratory investigations and will continue to do so in significant numbers, to compare the results obtained with well- and field-scale observations. In this contribution, we present several exemplary mechanical data sets for the reservoir and caprock, and compare these data with well-scale petrophysical and mechanical information, notably sonic, scratch and visual geological details with the aim to arrive at a multi-scale description of petrophysical and geomechanical rock properties. Our first comparison reveals a strong contrast in compressibility and strength between the reservoir and caprock, as well as a contribution of inelastic strain to the total strain response of the tested rock samples. We will discuss the observed mechanical stratigraphy in considering regional and field scale deformation patterns.

  13. Perfectly matched multiscale simulations

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohu

    In this dissertation, the Perfectly Matched Multiscale Simulations (PMMS), a method of discrete-to-continuum multiscale scale computation is studied, revised and extended. In particular, the role of the Perfectly Matched Layer (PML) in PMMS is carefully studied. We show that instead of following the PML theory of continuum, the PML equations of motion in PMMS can be derived by stretching the inter-atomic equilibrium distance. As a result, the displacement solution in the PML region has the desired spatial damping property. It is also shown that the dispersion relationship in the PML region is different from the one in the original lattice. And a reflection coefficient is computed. We also incorporate the local Quasicontinuum (QC) theory with the cohesive Finite Element (FE) method to form a cohesive QC scheme which can deal with arbitrary discontinuities. This idea is built into the PMMS method to simulate a moving screw dislocation. The second part of the dissertation is to extend PMMS to finite temperature. A multiscale thermodynamics is proposed based on the idea of distributed coarse scale thermostats. Each coarse scale node is viewed as a thermostat and has part of atoms associated with it. The atomic motion at the fine scale level is governed by the Nose-Hoover dynamics. At the coarse scale, the expression of a coarse-grained Helmholtz free energy is derived and coupled thermo-mechanical equations are formulated based on it. With the proposed framework, the finite-temperature PMMS method is capable of simulating problems with drastic temperature change. Several numerical examples are computed to validate the method.

  14. Multiscale methods for nanoengineering

    NASA Astrophysics Data System (ADS)

    Jolley, Kenny

    This project is presented in two sections. Two different multiscale models are developed in order to increase the computational speed of two well known atomistic algorithms, Molecular Dynamics (MD) and Kinetic Monte Carlo (KMC). In Section I, the MD method is introduced. Following this, a multiscale method of linking an MD simulation of heat conduction to a finite element (FE) simulation is presented. The method is simple to implement into a conventional MD code and is independent of the atomistic model employed. This bridge between the FE and MD simulations works by ensuring that energy is conserved across the FE/MD boundary. The multiscale simulation allows for the investigation of large systems which are beyond the range of MD. The method is tested extensively in the steady state and transient regimes, and is shown to agree with well with large scale MD and FE simulations. Furthermore, the method removes the artificial boundary effects due to the thermostats and hence allows exact temperatures and temperature gradients to be imposed on to an MD simulation. This allows for better study of temperature gradients on crystal defects etc.. In Section II, the KMC method is introduced. A continuum model for the KMC method is presented and compared to the standard KMC model of surface diffusion. This method replaces the many discrete back and forth atom jumps performed by a standard KMC algorithm with a single flux that can evolve in time. Elastic strain is then incorporated into both algorithms and used to simulate atom deposition upon a substrate by Molecular Beam Epitaxy. Quantum dot formation due to a mismatch in the lattice spacing between a substrate and a deposited film is readily observed in both models. Furthermore, by depositing alternating layers of substrate and deposit, self-organised quantum dot super-lattices are observed in both models..

  15. Structural and statistical characterization of joints and multi-scale faults in an alternating sandstone and shale turbidite sequence at the Santa Susana Field Laboratory: Implications for their effects on groundwater flow and contaminant transport

    NASA Astrophysics Data System (ADS)

    Cilona, Antonino; Aydin, Atilla; Likerman, Jeremias; Parker, Beth; Cherry, John

    2016-04-01

    This paper describes the properties of faults and fractures in the Upper Cretaceous Chatsworth Formation exposed at Santa Susana Field Laboratory and its surroundings (Simi Hills, California), where groundwater flow and contamination have been studied for over three decades. The complex depositional architecture of this turbidite consisting of alternating sandstones and shales, interacting with formative stress conditions are responsible for multi-scale fault hierarchies and permeable fractures in which nearly all groundwater flow occurs. Intensity and distribution of background fractures and their relation to bedding thickness are established for sandstones, the dominant lithology. The architecture of faults with increasing displacement is described, and relationships among fault dimensional parameters captured. Data from ∼400 boreholes and piezometers reveal the effect of faults and fractures on groundwater flow. Large hydraulic head differences, observed across fault zones with shale-rich cores, indicate these structures as cross-flow barriers. Moreover, hydraulic head profiles under ambient conditions, and pumping tests suggest strong hydraulic connectivity in all directions to depth of hundreds of meters. This outcrop-based structural characterization relates the horizontal hydraulic conductivity to the observed well-connected fracture network, and explains the strong vertical connectivity across low-hydraulic conductivity shales as faults and sheared fractures provide flow pathways.

  16. Multiscale modeling of chalcogenides

    NASA Astrophysics Data System (ADS)

    Mauro, John C.

    Chalcogenide glasses exhibit unique properties applicable to a wide range of fields, including electrical and optical switching and the transmission of infrared radiation. In this thesis, we adopt a hierarchical multiscale modeling approach to investigate the fundamental physics of chalcogenide systems. Our multiscale modeling begins in Part I at the quantum mechanical level, where we use the highly accurate Moller-Plesset perturbation technique to derive interaction potentials for elemental and heterogeneous chalcogenide systems. The resulting potentials consist of two-, three-, and effective four-body terms. In Part II, we use these ab initio potentials in classical Monte Carlo simulations to investigate the structure of chalcogenide glasses. We discuss our simulation results in relation to the Phillips model of topological constraints, which predicts critical behavior in chalcogenide systems as a function of average coordination number. Finally, in Part III we address the issue of glass transition range behavior. After reviewing previous models of the glass transition, we derive a new model based on nonequilibrium statistical mechanics and an energy landscape formalism. The new model requires as input a description of inherent structure energies and the transition energies between these structures. To address this issue, we derive an eigenvector-following technique for mapping a multidimensional potential energy landscape. This technique is then extended for application to enthalpy landscapes. Our model will enable the first-ever calculation of glass transition behavior based on only ab initio physics.

  17. Multiscale Cloud System Modeling

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Moncrieff, Mitchell W.

    2009-01-01

    The central theme of this paper is to describe how cloud system resolving models (CRMs) of grid spacing approximately 1 km have been applied to various important problems in atmospheric science across a wide range of spatial and temporal scales and how these applications relate to other modeling approaches. A long-standing problem concerns the representation of organized precipitating convective cloud systems in weather and climate models. Since CRMs resolve the mesoscale to large scales of motion (i.e., 10 km to global) they explicitly address the cloud system problem. By explicitly representing organized convection, CRMs bypass restrictive assumptions associated with convective parameterization such as the scale gap between cumulus and large-scale motion. Dynamical models provide insight into the physical mechanisms involved with scale interaction and convective organization. Multiscale CRMs simulate convective cloud systems in computational domains up to global and have been applied in place of contemporary convective parameterizations in global models. Multiscale CRMs pose a new challenge for model validation, which is met in an integrated approach involving CRMs, operational prediction systems, observational measurements, and dynamical models in a new international project: the Year of Tropical Convection, which has an emphasis on organized tropical convection and its global effects.

  18. Multiscale reactive molecular dynamics

    NASA Astrophysics Data System (ADS)

    Knight, Chris; Lindberg, Gerrick E.; Voth, Gregory A.

    2012-12-01

    Many processes important to chemistry, materials science, and biology cannot be described without considering electronic and nuclear-level dynamics and their coupling to slower, cooperative motions of the system. These inherently multiscale problems require computationally efficient and accurate methods to converge statistical properties. In this paper, a method is presented that uses data directly from condensed phase ab initio simulations to develop reactive molecular dynamics models that do not require predefined empirical functions. Instead, the interactions used in the reactive model are expressed as linear combinations of interpolating functions that are optimized by using a linear least-squares algorithm. One notable benefit of the procedure outlined here is the capability to minimize the number of parameters requiring nonlinear optimization. The method presented can be generally applied to multiscale problems and is demonstrated by generating reactive models for the hydrated excess proton and hydroxide ion based directly on condensed phase ab initio molecular dynamics simulations. The resulting models faithfully reproduce the water-ion structural properties and diffusion constants from the ab initio simulations. Additionally, the free energy profiles for proton transfer, which is sensitive to the structural diffusion of both ions in water, are reproduced. The high fidelity of these models to ab initio simulations will permit accurate modeling of general chemical reactions in condensed phase systems with computational efficiency orders of magnitudes greater than currently possible with ab initio simulation methods, thus facilitating a proper statistical sampling of the coupling to slow, large-scale motions of the system.

  19. Multiscale reactive molecular dynamics

    PubMed Central

    Knight, Chris; Lindberg, Gerrick E.; Voth, Gregory A.

    2012-01-01

    Many processes important to chemistry, materials science, and biology cannot be described without considering electronic and nuclear-level dynamics and their coupling to slower, cooperative motions of the system. These inherently multiscale problems require computationally efficient and accurate methods to converge statistical properties. In this paper, a method is presented that uses data directly from condensed phase ab initio simulations to develop reactive molecular dynamics models that do not require predefined empirical functions. Instead, the interactions used in the reactive model are expressed as linear combinations of interpolating functions that are optimized by using a linear least-squares algorithm. One notable benefit of the procedure outlined here is the capability to minimize the number of parameters requiring nonlinear optimization. The method presented can be generally applied to multiscale problems and is demonstrated by generating reactive models for the hydrated excess proton and hydroxide ion based directly on condensed phase ab initio molecular dynamics simulations. The resulting models faithfully reproduce the water-ion structural properties and diffusion constants from the ab initio simulations. Additionally, the free energy profiles for proton transfer, which is sensitive to the structural diffusion of both ions in water, are reproduced. The high fidelity of these models to ab initio simulations will permit accurate modeling of general chemical reactions in condensed phase systems with computational efficiency orders of magnitudes greater than currently possible with ab initio simulation methods, thus facilitating a proper statistical sampling of the coupling to slow, large-scale motions of the system. PMID:23249062

  20. Multiscale entropy to distinguish physiologic and synthetic RR time series.

    PubMed

    Costa, M; Goldberger, A L; Peng, C-K

    2002-01-01

    We address the challenge of distinguishing physiologic interbeat interval time series from those generated by synthetic algorithms via a newly developed multiscale entropy method. Traditional measures of time series complexity only quantify the degree of regularity on a single time scale. However, many physiologic variables, such as heart rate, fluctuate in a very complex manner and present correlations over multiple time scales. We have proposed a new method to calculate multiscale entropy from complex signals. In order to distinguish between physiologic and synthetic time series, we first applied the method to a learning set of RR time series derived from healthy subjects. We empirically established selected criteria characterizing the entropy dependence on scale factor for these datasets. We then applied this algorithm to the CinC 2002 test datasets. Using only the multiscale entropy method, we correctly classified 48 of 50 (96%) time series. In combination with Fourier spectral analysis, we correctly classified all time series. PMID:14686448

  1. Performance of distributed multiscale simulations

    PubMed Central

    Borgdorff, J.; Ben Belgacem, M.; Bona-Casas, C.; Fazendeiro, L.; Groen, D.; Hoenen, O.; Mizeranschi, A.; Suter, J. L.; Coster, D.; Coveney, P. V.; Dubitzky, W.; Hoekstra, A. G.; Strand, P.; Chopard, B.

    2014-01-01

    Multiscale simulations model phenomena across natural scales using monolithic or component-based code, running on local or distributed resources. In this work, we investigate the performance of distributed multiscale computing of component-based models, guided by six multiscale applications with different characteristics and from several disciplines. Three modes of distributed multiscale computing are identified: supplementing local dependencies with large-scale resources, load distribution over multiple resources, and load balancing of small- and large-scale resources. We find that the first mode has the apparent benefit of increasing simulation speed, and the second mode can increase simulation speed if local resources are limited. Depending on resource reservation and model coupling topology, the third mode may result in a reduction of resource consumption. PMID:24982258

  2. The Magnetospheric Multiscale Constellation

    NASA Astrophysics Data System (ADS)

    Tooley, C. R.; Black, R. K.; Robertson, B. P.; Stone, J. M.; Pope, S. E.; Davis, G. T.

    2016-03-01

    The Magnetospheric Multiscale (MMS) mission is the fourth mission of the Solar Terrestrial Probe (STP) program of the National Aeronautics and Space Administration (NASA). The MMS mission was launched on March 12, 2015. The MMS mission consists of four identically instrumented spin-stabilized observatories which are flown in formation to perform the first definitive study of magnetic reconnection in space. The MMS mission was presented with numerous technical challenges, including the simultaneous construction and launch of four identical large spacecraft with 100 instruments total, stringent electromagnetic cleanliness requirements, closed-loop precision maneuvering and pointing of spinning flexible spacecraft, on-board GPS based orbit determination far above the GPS constellation, and a flight dynamics design that enables formation flying with separation distances as small as 10 km. This paper describes the overall mission design and presents an overview of the design, testing, and early on-orbit operation of the spacecraft systems and instrument suite.

  3. MULTISCALE THERMOHYDROLOGIC MODEL

    SciTech Connect

    T.A. Buscheck

    2001-12-21

    The purpose of the Multiscale Thermohydrologic Model (MSTHM) is to describe the thermohydrologic evolution of the near-field environment (NFE) and engineered barrier system (EBS) throughout the potential high-level nuclear waste repository at Yucca Mountain for a particular engineering design (CRWMS M&O 2000c). The process-level model will provide thermohydrologic (TH) information and data (such as in-drift temperature, relative humidity, liquid saturation, etc.) for use in other technical products. This data is provided throughout the entire repository area as a function of time. The MSTHM couples the Smeared-heat-source Drift-scale Thermal-conduction (SDT), Line-average-heat-source Drift-scale Thermohydrologic (LDTH), Discrete-heat-source Drift-scale Thermal-conduction (DDT), and Smeared-heat-source Mountain-scale Thermal-conduction (SMT) submodels such that the flow of water and water vapor through partially-saturated fractured rock is considered. The MSTHM accounts for 3-D drift-scale and mountain-scale heat flow, repository-scale variability of stratigraphy and infiltration flux, and waste package (WP)-to-WP variability in heat output from WPs. All submodels use the nonisothermal unsaturated-saturated flow and transport (NUFT) simulation code. The MSTHM is implemented in several data-processing steps. The four major steps are: (1) submodel input-file preparation, (2) execution of the four submodel families with the use of the NUFT code, (3) execution of the multiscale thermohydrologic abstraction code (MSTHAC), and (4) binning and post-processing (i.e., graphics preparation) of the output from MSTHAC. Section 6 describes the MSTHM in detail. The objectives of this Analyses and Model Report (AMR) are to investigate near field (NF) and EBS thermohydrologic environments throughout the repository area at various evolution periods, and to provide TH data that may be used in other process model reports.

  4. Demonstration of a Novel, Integrated, Multi-Scale Procedure for High-Resolution 3D Reservoir Characterization and Improved CO2-EOR/Sequestration Management, SACROC Unit

    SciTech Connect

    Scott R. Reeves

    2007-09-30

    The primary goal of this project was to demonstrate a new and novel approach for high resolution, 3D reservoir characterization that can enable better management of CO{sub 2} enhanced oil recovery (EOR) projects and, looking to the future, carbon sequestration projects. The approach adopted has been the subject of previous research by the DOE and others, and relies primarily upon data-mining and advanced pattern recognition approaches. This approach honors all reservoir characterization data collected, but accepts that our understanding of how these measurements relate to the information of most interest, such as how porosity and permeability vary over a reservoir volume, is imperfect. Ideally the data needed for such an approach includes surface seismic to provide the greatest amount of data over the entire reservoir volume of interest, crosswell seismic to fill the resolution gap between surface seismic and wellbore-scale measurements, geophysical well logs to provide the vertical resolution sought, and core data to provide the tie to the information of most interest. These data are combined via a series of one or more relational models to enable, in its most successful application, the prediction of porosity and permeability on a vertical resolution similar to logs at each surface seismic trace location. In this project, the procedure was applied to the giant (and highly complex) SACROC unit of the Permian basin in West Texas, one of the world's largest CO{sub 2}-EOR projects and a potentially world-class geologic sequestration site. Due to operational scheduling considerations on the part of the operator of the field, the crosswell data was not obtained during the period of project performance (it is currently being collected however as part of another DOE project). This compromised the utility of the surface seismic data for the project due to the resolution gap between it and the geophysical well logs. An alternative approach was adopted that utilized a

  5. Multiscale full waveform inversion

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas; Trampert, Jeannot; Cupillard, Paul; Saygin, Erdinc; Taymaz, Tuncay; Capdeville, Yann; Villaseñor, Antonio

    2013-07-01

    We develop and apply a full waveform inversion method that incorporates seismic data on a wide range of spatio-temporal scales, thereby constraining the details of both crustal and upper-mantle structure. This is intended to further our understanding of crust-mantle interactions that shape the nature of plate tectonics, and to be a step towards improved tomographic models of strongly scale-dependent earth properties, such as attenuation and anisotropy. The inversion for detailed regional earth structure consistently embedded within a large-scale model requires locally refined numerical meshes that allow us to (1) model regional wave propagation at high frequencies, and (2) capture the inferred fine-scale heterogeneities. The smallest local grid spacing sets the upper bound of the largest possible time step used to iteratively advance the seismic wave field. This limitation leads to extreme computational costs in the presence of fine-scale structure, and it inhibits the construction of full waveform tomographic models that describe earth structure on multiple scales. To reduce computational requirements to a feasible level, we design a multigrid approach based on the decomposition of a multiscale earth model with widely varying grid spacings into a family of single-scale models where the grid spacing is approximately uniform. Each of the single-scale models contains a tractable number of grid points, which ensures computational efficiency. The multi-to-single-scale decomposition is the foundation of iterative, gradient-based optimization schemes that simultaneously and consistently invert data on all scales for one multi-scale model. We demonstrate the applicability of our method in a full waveform inversion for Eurasia, with a special focus on Anatolia where coverage is particularly dense. Continental-scale structure is constrained by complete seismic waveforms in the 30-200 s period range. In addition to the well-known structural elements of the Eurasian mantle

  6. The Magnetospheric Multiscale Magnetometers

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Anderson, B. J.; Baumjohann, W.; Bromund, K. R.; Dearborn, D.; Fischer, D.; Le, G.; Leinweber, H. K.; Leneman, D.; Magnes, W.; Means, J. D.; Moldwin, M. B.; Nakamura, R.; Pierce, D.; Plaschke, F.; Rowe, K. M.; Slavin, J. A.; Strangeway, R. J.; Torbert, R.; Hagen, C.; Jernej, I.; Valavanoglou, A.; Richter, I.

    2016-03-01

    The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University's Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored on board so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.

  7. Multiscale coherent structures in tokamak plasma turbulence

    SciTech Connect

    Xu, G. S.; Wan, B. N.; Zhang, W.; Yang, Q. W.; Wang, L.; Wen, Y. Z.

    2006-10-15

    A 12-tip poloidal probe array is used on the HT-7 superconducting tokamak [Li, Wan, and Mao, Plasma Phys. Controlled Fusion 42, 135 (2000)] to measure plasma turbulence in the edge region. Some statistical analysis techniques are used to characterize the turbulence structures. It is found that the plasma turbulence is composed of multiscale coherent structures, i.e., turbulent eddies and there is self-similarity in a relative short scale range. The presence of the self-similarity is found due to the structural similarity of these eddies between different scales. These turbulent eddies constitute the basic convection cells, so the self-similar range is just the dominant scale range relevant to transport. The experimental results also indicate that the plasma turbulence is dominated by low-frequency and long-wavelength fluctuation components and its dispersion relation shows typical electron-drift-wave characteristics. Some large-scale coherent structures intermittently burst out and exhibit a very long poloidal extent, even longer than 6 cm. It is found that these large-scale coherent structures are mainly contributed by the low-frequency and long-wavelength fluctuating components and their presence is responsible for the observations of long-range correlations, i.e., the correlation in the scale range much longer than the turbulence decorrelation scale. These experimental observations suggest that the coexistence of multiscale coherent structures results in the self-similar turbulent state.

  8. Characterization of multi-scale porous structure of fly ash/phosphate geopolymer hollow sphere structures: from submillimeter to nano-scale.

    PubMed

    Li, Ruifeng; Wu, Gaohui; Jiang, Longtao; Sun, Dongli

    2015-01-01

    In the present work, the porous structure of fly ash/phosphate geopolymer hollow sphere structures (FPGHSS), prepared by pre-bonding and curing technology, has been characterized by multi-resolution methods from sub-millimeter to nano-scale. Micro-CT and confocal microscopy could provide the macroscopic distribution of porous structure on sub-millimeter scale, and hollow fly ashes with sphere shape and several sub-millimeter open cells with irregular shape were identified. SEM is more suitable to illustrate the distribution of micro-sized open and closed cells, and it was found that the open cells of FPGHSS were mainly formed in the interstitial porosity between fly ashes. Mercury porosimeter measurement showed that the micro-sized open cell of FPGHSS demonstrated a normal/bimodal distribution, and the peaks of pore size distribution were mainly around 100 and 10 μm. TEM observation revealed that the phosphate geopolymer was mainly composed of the porous area with nano-pores and dense areas, which were amorphous Al-O-P phase and α-Al2O3 respectively. The pore size of nano-pores demonstrated a quasi-normal distribution from about 10 to 100 nm. Therefore, detailed information of the porous structure of FPGHSS could be revealed using multiple methods. PMID:25282522

  9. Multi-scale characterization of pore evolution in a combustion metamorphic complex, Hatrurim basin, Israel: Combining (ultra) small-angle neutron scattering and image analysis

    NASA Astrophysics Data System (ADS)

    Wang, Hsiu-Wen; Anovitz, Lawrence M.; Burg, Avihu; Cole, David R.; Allard, Lawrence F.; Jackson, Andrew J.; Stack, Andrew G.; Rother, Gernot

    2013-11-01

    Backscattered scanning electron micrograph and ultra small- and small-angle neutron scattering data have been combined to provide statistically meaningful data on the pore/grain structure and pore evolution of combustion metamorphic complexes from the Hatrurim basin, Israel. Three processes, anti-sintering roughening, alteration of protolith (dehydration, decarbonation, and oxidation) and crystallization of high-temperature minerals, occurred simultaneously, leading to significant changes in observed pore/grain structures. Pore structures in the protoliths, and in low- and high-grade metamorphic rocks show surface (Ds) and mass (Dm) pore fractal geometries with gradual increases in both Ds and Dm values as a function of metamorphic grade. This suggests that increases in pore volume and formation of less branching pore networks are accompanied by a roughening of pore/grain interfaces. Additionally, pore evolution during combustion metamorphism is also characterized by reduced contributions from small-scale pores to the cumulative porosity in the high-grade rocks. At high temperatures, small-scale pores may be preferentially closed by the formation of high-temperature minerals, producing a rougher morphology with increasing temperature. Alternatively, large-scale pores may develop at the expense of small-scale pores. These observations (pore fractal geometry and cumulative porosity) indicate that the evolution of pore/grain structures is correlated with the growth of high-temperature phases and is a consequence of the energy balance between pore/grain surface energy and energy arising from heterogeneous phase contacts. The apparent pore volume density further suggests that the localized time/temperature development of the high-grade Hatrurim rocks is not simply an extension of that of the low-grade rocks. The former likely represents the "hot spots (burning foci)" in the overall metamorphic terrain while the latter may represent contact aureoles.

  10. Multi-scale characterization of pore evolution in a combustion metamorphic complex, Hatrurim basin, Israel: Combining (ultra) small-angle neutron scattering and image analysis

    SciTech Connect

    Wang, Hsiu-Wen; Anovitz, Lawrence {Larry} M; Burg, Avihu; Cole, David; Allard Jr, Lawrence Frederick; Jackson, Andrew J; Stack, Andrew G; Rother, Gernot; Ciarlette, Diane D

    2013-01-01

    Backscattered scanning electron micrograph and ultra small- and small-angle neutron scattering data have been combined to provide statistically meaningful data on the pore/grain structure and pore evolution of combustion metamorphic complexes from the Hatrurim basin, Israel. Three processes, anti-sintering roughening, alteration of protolith (dehydration, decarbonation, and oxidation) and crystallization of high-temperature minerals, occurred simultaneously, leading to significant changes in observed pore/grain structures. Pore structures in the protoliths, and in lowand high-grade metamorphic rocks show surface (Ds) and mass (Dm) pore fractal geometries with gradual increases in both Ds and Dm values as a function of metamorphic grade. This suggests that increases in pore volume and formation of less branching pore networks are accompanied by a roughening of pore/grain interfaces. Additionally, pore evolution during combustion metamorphism is also characterized by reduced contributions from small-scale pores to the cumulative porosity in the high-grade rocks. At high temperatures, small-scale pores may be preferentially closed by the formation of high-temperature minerals, producing a rougher morphology with increasing temperature. Alternatively, large-scale pores may develop at the expense of small-scale pores. These observations (pore fractal geometry and cumulative porosity) indicate that the evolution of pore/grain structures is correlated with the growth of high-temperature phases and is a consequence of the energy balance between pore/grain surface energy and energy arising from heterogeneous phase contacts. The apparent pore volume density further suggests that the localized time/temperature development of the high-grade Hatrurim rocks is not simply an extension of that of the low-grade rocks. The former likely represents the "hot spots (burning foci)" in the overall metamorphic terrain while the latter may represent contact aureoles.

  11. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Delozier, Donavon M.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multi-functionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to approx. 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were fabricated by injecting the mixtures at 260-280 C into a stainless steel tool followed by curing for 1 h at 371 C. The tool was designed to impart high shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy and Raman spectroscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites,

  12. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multifunctionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were made by injecting the mixtures at 260-280 C into an Invar tool followed by curing for 1 h at 371 C. The tool was designed to impart shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites, moldings

  13. Multiscale Thermohydrologic Model

    SciTech Connect

    T. Buscheck

    2004-10-12

    The purpose of the multiscale thermohydrologic model (MSTHM) is to predict the possible range of thermal-hydrologic conditions, resulting from uncertainty and variability, in the repository emplacement drifts, including the invert, and in the adjoining host rock for the repository at Yucca Mountain. Thus, the goal is to predict the range of possible thermal-hydrologic conditions across the repository; this is quite different from predicting a single expected thermal-hydrologic response. The MSTHM calculates the following thermal-hydrologic parameters: temperature, relative humidity, liquid-phase saturation, evaporation rate, air-mass fraction, gas-phase pressure, capillary pressure, and liquid- and gas-phase fluxes (Table 1-1). These thermal-hydrologic parameters are required to support ''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504]). The thermal-hydrologic parameters are determined as a function of position along each of the emplacement drifts and as a function of waste package type. These parameters are determined at various reference locations within the emplacement drifts, including the waste package and drip-shield surfaces and in the invert. The parameters are also determined at various defined locations in the adjoining host rock. The MSTHM uses data obtained from the data tracking numbers (DTNs) listed in Table 4.1-1. The majority of those DTNs were generated from the following analyses and model reports: (1) ''UZ Flow Model and Submodels'' (BSC 2004 [DIRS 169861]); (2) ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2004); (3) ''Calibrated Properties Model'' (BSC 2004 [DIRS 169857]); (4) ''Thermal Conductivity of the Potential Repository Horizon'' (BSC 2004 [DIRS 169854]); (5) ''Thermal Conductivity of the Non-Repository Lithostratigraphic Layers'' (BSC 2004 [DIRS 170033]); (6) ''Ventilation Model and Analysis Report'' (BSC 2004 [DIRS 169862]); (7) ''Heat Capacity

  14. Multi-scale characterization of a Contourite Depositional System from Gamma Ray data analysis. Insights from IODP Expedition 339 in the Gulf of Cadiz

    NASA Astrophysics Data System (ADS)

    Lofi, Johanna; Ducassou, Emmanuelle; Galvani, Aurélie; Rodríguez-Tovar, Francisco Javier; Williams, Trevor; Hernández-Molina, Francisco Javier; Stow, Dorrik; Pardo-Igúzquiza, Eulogio

    2014-05-01

    Contourite Depositional Systems (CDS) generated by bottom current activity have been described in most oceanic basins, especially on the continental slope, rises and abyssal plains. Beside an economic light due to the continuous expansion of hydrocarbon exploration towards deeper water, CDS form sedimentary archives that can be crucial for paleoceanographic reconstructions. Recently, IODP Expedition 339 was conducted in the Gulf of Cadiz in order to investigate the CDS under the influence of the Mediterranean Outflow Water (MOW). Five sites were successfully drilled, cored and logged, making this area an ideal ground for testing the contourite paradigm over a 5 Ma long record. Following opening of the Gibraltar Gateway, preliminary results show that contourite deposition started from 4.2-4.5 Ma, increasing in the Quaternary. Significant widespread unconformities, present in all sites but with hiatuses of variable duration, are interpreted as a signal of intensified MOW, coupled with flow confinement. Expedition 339 data allows characterization of CDS from both seismic, core and well log data. Downhole logging measurements acquired during the expedition provided continuous in situ Natural and Spectral Gamma Ray (GR) records of the drilled formation, allowing for the analysis of the interaction between bottom circulation and sedimentary deposits at several scales: - At small scale, the good core recovery allows core/log integration. Grain size analysis performed on cores from Site U1386 have been combined with Gamma ray data, primarily tracking clay content, measured on cores and in open hole. The correlation confirm that high GR values correlate well with muddy intervals while low GR values reflect coarse-grained intervals; - At an intermediate scale, spectral analysis performed on GR logs at 3 sites (U1386C, U1389E and U1387C) confirm the record of orbital-scale variations in the sediment properties of contourites over the last 1.6 Ma; - At a larger scale, site to

  15. Electrochemical characterization of monoclinic and orthorhombic Li3CrF6 as positive electrodes in lithium-ion batteries synthesized by a sol-gel process with environmentally benign chemicals

    NASA Astrophysics Data System (ADS)

    Lieser, Georg; Winkler, Volker; Geßwein, Holger; de Biasi, Lea; Glatthaar, Sven; Hoffmann, M. J.; Ehrenberg, Helmut; Binder, Joachim R.

    2015-10-01

    Lithium transition metal fluorides (Li3MF6; M = Fe, V) with cryolite structure are investigated as positive electrode materials for lithium-ion batteries. A novel sol-gel process with trifluoroacetic acid as fluorine source was used to synthesize monoclinic and orthorhombic Li3CrF6. A ball milling process with Li3CrF6, binder, and conductive agent was applied to form a Li3CrF6 composite, which was electrochemically characterized against lithium metal for the first time. The electrochemical properties of two different modifications are quite similar, with a reversible specific capacity of 111 mAhg-1 for monoclinic Li3CrF6 and 106 mAhg-1 for orthorhombic Li3CrF6 (1 eq. Li ≙ 143 mAhg-1). The electrochemically active redox couple CrIII/CrII was confirmed by X-ray photoelectron spectroscopy.

  16. Multi-Scale Infrastructure Assessment

    EPA Science Inventory

    The U.S. Environmental Protection Agency’s (EPA) multi-scale infrastructure assessment project supports both water resource adaptation to climate change and the rehabilitation of the nation’s aging water infrastructure by providing tools, scientific data and information to progra...

  17. Multiscale Model Describing Bacterial Adhesion and Detachment.

    PubMed

    Ostvar, Sassan; Wood, Brian D

    2016-05-24

    Bacterial surfaces are complex structures with nontrivial adhesive properties. The physics of bacterial adhesion deviates from that of ideal colloids as a result of cell-surface roughness and because of the mechanical properties of the polymers covering the cell surface. In the present study, we develop a simple multiscale model for the interplay between the potential energy functions that characterize the cell surface biopolymers and their interaction with the extracellular environment. We then use the model to study a discrete network of bonds in the presence of significant length heterogeneities in cell-surface polymers. The model we present is able to generate force curves (both approach and retraction) that closely resemble those measured experimentally. Our results show that even small-length-scale heterogeneities can lead to macroscopically nonlinear behavior that is qualitatively and quantitatively different from the homogeneous case. We also report on the energetic consequences of such structural heterogeneity. PMID:27129780

  18. Multiscale decomposition for heterogeneous land-atmosphere systems

    NASA Astrophysics Data System (ADS)

    Liu, Shaofeng; Shao, Yaping; Hintz, Michael; Lennartz-Sassinek, Sabine

    2015-02-01

    The land-atmosphere system is characterized by pronounced land surface heterogeneity and vigorous atmospheric turbulence both covering a wide range of scales. The multiscale surface heterogeneities and multiscale turbulent eddies interact nonlinearly with each other. Understanding these multiscale processes quantitatively is essential to the subgrid parameterizations for weather and climate models. In this paper, we propose a method for surface heterogeneity quantification and turbulence structure identification. The first part of the method is an orthogonal transform in the probability density function (PDF) domain, in contrast to the orthogonal wavelet transforms which are performed in the physical space. As the basis of the whole method, the orthogonal PDF transform (OPT) is used to asymptotically reconstruct the original signals by representing the signal values with multilevel approximations. The "patch" idea is then applied to these reconstructed fields in order to recognize areas at the land surface or in turbulent flows that are of the same characteristics. A patch here is a connected area with the same approximation. For each recognized patch, a length scale is then defined to build the energy spectrum. The OPT and related energy spectrum analysis, as a whole referred to as the orthogonal PDF decomposition (OPD), is applied to two-dimensional heterogeneous land surfaces and atmospheric turbulence fields for test. The results show that compared to the wavelet transforms, the OPD can reconstruct the original signal more effectively, and accordingly, its energy spectrum represents the signal's multiscale variation more accurately. The method we propose in this paper is of general nature and therefore can be of interest for problems of multiscale process description in other geophysical disciplines.

  19. MULTISCALE THERMOHYDROLOGIC MODEL

    SciTech Connect

    T. Buscheck

    2005-07-07

    The intended purpose of the multiscale thermohydrologic model (MSTHM) is to predict the possible range of thermal-hydrologic conditions, resulting from uncertainty and variability, in the repository emplacement drifts, including the invert, and in the adjoining host rock for the repository at Yucca Mountain. The goal of the MSTHM is to predict a reasonable range of possible thermal-hydrologic conditions within the emplacement drift. To be reasonable, this range includes the influence of waste-package-to-waste-package heat output variability relevant to the license application design, as well as the influence of uncertainty and variability in the geologic and hydrologic conditions relevant to predicting the thermal-hydrologic response in emplacement drifts. This goal is quite different from the goal of a model to predict a single expected thermal-hydrologic response. As a result, the development and validation of the MSTHM and the associated analyses using this model are focused on the goal of predicting a reasonable range of thermal-hydrologic conditions resulting from parametric uncertainty and waste-package-to-waste-package heat-output variability. Thermal-hydrologic conditions within emplacement drifts depend primarily on thermal-hydrologic conditions in the host rock at the drift wall and on the temperature difference between the drift wall and the drip-shield and waste-package surfaces. Thus, the ability to predict a reasonable range of relevant in-drift MSTHM output parameters (e.g., temperature and relative humidity) is based on valid predictions of thermal-hydrologic processes in the host rock, as well as valid predictions of heat-transfer processes between the drift wall and the drip-shield and waste-package surfaces. Because the invert contains crushed gravel derived from the host rock, the invert is, in effect, an extension of the host rock, with thermal and hydrologic properties that have been modified by virtue of the crushing (and the resulting

  20. The Magnetospheric Multiscale Mission

    NASA Astrophysics Data System (ADS)

    Burch, James

    Magnetospheric Multiscale (MMS), a NASA four-spacecraft mission scheduled for launch in November 2014, will investigate magnetic reconnection in the boundary regions of the Earth’s magnetosphere, particularly along its dayside boundary with the solar wind and the neutral sheet in the magnetic tail. Among the important questions about reconnection that will be addressed are the following: Under what conditions can magnetic-field energy be converted to plasma energy by the annihilation of magnetic field through reconnection? How does reconnection vary with time, and what factors influence its temporal behavior? What microscale processes are responsible for reconnection? What determines the rate of reconnection?
In order to accomplish its goals the MMS spacecraft must probe both those regions in which the magnetic fields are very nearly antiparallel and regions where a significant guide field exists. From previous missions we know the approximate speeds with which reconnection layers move through space to be from tens to hundreds of km/s. For electron skin depths of 5 to 10 km, the full 3D electron population (10 eV to above 20 keV) has to be sampled at rates greater than 10/s. The MMS Fast-Plasma Instrument (FPI) will sample electrons at greater than 30/s. Because the ion skin depth is larger, FPI will make full ion measurements at rates of greater than 6/s. 3D E-field measurements will be made by MMS once every ms. MMS will use an Active Spacecraft Potential Control device (ASPOC), which emits indium ions to neutralize the photoelectron current and keep the spacecraft from charging to more than +4 V. Because ion dynamics in Hall reconnection depend sensitively on ion mass, MMS includes a new-generation Hot Plasma Composition Analyzer (HPCA) that corrects problems with high proton fluxes that have prevented accurate ion-composition measurements near the dayside magnetospheric boundary. Finally, Energetic Particle Detector (EPD) measurements of electrons and

  1. A heterogeneous multiscale method for poroelasticity

    NASA Astrophysics Data System (ADS)

    Delgado, Paul M.

    In this thesis, we develop and analyze a heterogeneous multiscale model for coupled fluid flow and solid deformation in porous media based on operator splitting and finite volume method. The splitting method results in two elliptic multiscale PDE's in the form of a reaction diffusion equation and a linear elasticity equation. We extend our previous multiscale method from 1D to higher dimensions and develop new approaches for the inclusion of mixed boundary conditions and source terms. We derive an error estimate for our multiscale method and analyze the stability of our splitting method. We also test the effectiveness of our method in the case of steady state linear poroelasticity.

  2. Simulating and mapping spatial complexity using multi-scale techniques

    USGS Publications Warehouse

    De Cola, L.

    1994-01-01

    A central problem in spatial analysis is the mapping of data for complex spatial fields using relatively simple data structures, such as those of a conventional GIS. This complexity can be measured using such indices as multi-scale variance, which reflects spatial autocorrelation, and multi-fractal dimension, which characterizes the values of fields. These indices are computed for three spatial processes: Gaussian noise, a simple mathematical function, and data for a random walk. Fractal analysis is then used to produce a vegetation map of the central region of California based on a satellite image. This analysis suggests that real world data lie on a continuum between the simple and the random, and that a major GIS challenge is the scientific representation and understanding of rapidly changing multi-scale fields. -Author

  3. Multiscale effect of paint pulverization orientation on appearance after painting

    NASA Astrophysics Data System (ADS)

    Mezghani, S.; Zahouani, H.; Piezanowski, J.

    2011-08-01

    The perceived quality of a vehicle is strongly affected by paint appearance that shares major part of the outer car body panels. The painting process modifies the surface topography in a wide range of roughness and waviness scales, and consequently modifies the functionality of the surface in terms of appearance. Since painting process is a multistage process leading to stratified surfaces, a multiscale surface topography characterization approach is suited. In this paper, 2D multiscale signature of the painting process was introduced and applied to track the effect of the painting process working variable on painted surface topography in a wide range of wavelength. To this aim, experimental painting tests were performed using three painting orientation modes (horizontal, oblique and vertical) on random and deterministic metal sheet surface textures. Results show that the painting orientation mode affect only the wavelength band greater than 500 μm and optimal painting orientation depends strongly on the texture of the initial sheet surface.

  4. Multiscale Dynamics of Solar Magnetic Structures

    NASA Technical Reports Server (NTRS)

    Uritsky, Vadim M.; Davila, Joseph M.

    2012-01-01

    Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries.We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

  5. MULTISCALE DYNAMICS OF SOLAR MAGNETIC STRUCTURES

    SciTech Connect

    Uritsky, Vadim M.; Davila, Joseph M.

    2012-03-20

    Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

  6. Differential Geometry Based Multiscale Models

    PubMed Central

    Wei, Guo-Wei

    2010-01-01

    Large chemical and biological systems such as fuel cells, ion channels, molecular motors, and viruses are of great importance to the scientific community and public health. Typically, these complex systems in conjunction with their aquatic environment pose a fabulous challenge to theoretical description, simulation, and prediction. In this work, we propose a differential geometry based multiscale paradigm to model complex macromolecular systems, and to put macroscopic and microscopic descriptions on an equal footing. In our approach, the differential geometry theory of surfaces and geometric measure theory are employed as a natural means to couple the macroscopic continuum mechanical description of the aquatic environment with the microscopic discrete atom-istic description of the macromolecule. Multiscale free energy functionals, or multiscale action functionals are constructed as a unified framework to derive the governing equations for the dynamics of different scales and different descriptions. Two types of aqueous macromolecular complexes, ones that are near equilibrium and others that are far from equilibrium, are considered in our formulations. We show that generalized Navier–Stokes equations for the fluid dynamics, generalized Poisson equations or generalized Poisson–Boltzmann equations for electrostatic interactions, and Newton's equation for the molecular dynamics can be derived by the least action principle. These equations are coupled through the continuum-discrete interface whose dynamics is governed by potential driven geometric flows. Comparison is given to classical descriptions of the fluid and electrostatic interactions without geometric flow based micro-macro interfaces. The detailed balance of forces is emphasized in the present work. We further extend the proposed multiscale paradigm to micro-macro analysis of electrohydrodynamics, electrophoresis, fuel cells, and ion channels. We derive generalized Poisson–Nernst–Planck equations that

  7. Drug silica nanocomposite: preparation, characterization and skin permeation studies.

    PubMed

    Pilloni, Martina; Ennas, Guido; Casu, Mariano; Fadda, Anna Maria; Frongia, Francesca; Marongiu, Francesca; Sanna, Roberta; Scano, Alessandra; Valenti, Donatella; Sinico, Chiara

    2013-01-01

    The aim of this work was to evaluate silica nanocomposites as topical drug delivery systems for the model drug, caffeine. Preparation, characterization, and skin permeation properties of caffeine-silica nanocomposites are described. Caffeine was loaded into the nanocomposites by grinding the drug with mesoporous silica in a ball mill up to 10 h and the efficiency of the process was studied by XRPD. Formulations were characterized by several methods that include FTIR, XRPD, SEM and TEM. The successful loading of caffeine was demonstrated by XRPD and FTIR. Morphology was studied by SEM that showed particle size reduction while TEM demonstrated formation of both core-shell and multilayered caffeine-silica structures. Solid-state NMR spectra excluded chemical interactions between caffeine and silica matrix, thus confirming that no solid state reactions occurred during the grinding process. Influence of drug inclusion in silica nanocomposite on the in vitro caffeine diffusion into and through the skin was investigated in comparison with a caffeine gel formulation (reference), using newborn pig skin and vertical Franz diffusion cells. Results from the in vitro skin permeation experiments showed that inclusion into the nanocomposite reduced and delayed caffeine permeation from the silica nanocomposite in comparison with the reference, independently from the amount of the tested formulation. PMID:22324371

  8. Mathematical and Numerical Analyses of Peridynamics for Multiscale Materials Modeling

    SciTech Connect

    Du, Qiang

    2014-11-12

    generation atomistic-to-continuum multiscale simulations. In addition, a rigorous studyof nite element discretizations of peridynamics will be considered. Using the fact that peridynamics is spatially derivative free, we will also characterize the space of admissible peridynamic solutions and carry out systematic analyses of the models, in particular rigorously showing how peridynamics encompasses fracture and other failure phenomena. Additional aspects of the project include the mathematical and numerical analysis of peridynamics applied to stochastic peridynamics models. In summary, the project will make feasible mathematically consistent multiscale models for the analysis and design of advanced materials.

  9. The Adaptive Multi-scale Simulation Infrastructure

    SciTech Connect

    Tobin, William R.

    2015-09-01

    The Adaptive Multi-scale Simulation Infrastructure (AMSI) is a set of libraries and tools developed to support the development, implementation, and execution of general multimodel simulations. Using a minimal set of simulation meta-data AMSI allows for minimally intrusive work to adapt existent single-scale simulations for use in multi-scale simulations. Support for dynamic runtime operations such as single- and multi-scale adaptive properties is a key focus of AMSI. Particular focus has been spent on the development on scale-sensitive load balancing operations to allow single-scale simulations incorporated into a multi-scale simulation using AMSI to use standard load-balancing operations without affecting the integrity of the overall multi-scale simulation.

  10. Multiscale geometric modeling of macromolecules II: Lagrangian representation

    PubMed Central

    Feng, Xin; Xia, Kelin; Chen, Zhan; Tong, Yiying; Wei, Guo-Wei

    2013-01-01

    Geometric modeling of biomolecules plays an essential role in the conceptualization of biolmolecular structure, function, dynamics and transport. Qualitatively, geometric modeling offers a basis for molecular visualization, which is crucial for the understanding of molecular structure and interactions. Quantitatively, geometric modeling bridges the gap between molecular information, such as that from X-ray, NMR and cryo-EM, and theoretical/mathematical models, such as molecular dynamics, the Poisson-Boltzmann equation and the Nernst-Planck equation. In this work, we present a family of variational multiscale geometric models for macromolecular systems. Our models are able to combine multiresolution geometric modeling with multiscale electrostatic modeling in a unified variational framework. We discuss a suite of techniques for molecular surface generation, molecular surface meshing, molecular volumetric meshing, and the estimation of Hadwiger’s functionals. Emphasis is given to the multiresolution representations of biomolecules and the associated multiscale electrostatic analyses as well as multiresolution curvature characterizations. The resulting fine resolution representations of a biomolecular system enable the detailed analysis of solvent-solute interaction, and ion channel dynamics, while our coarse resolution representations highlight the compatibility of protein-ligand bindings and possibility of protein-protein interactions. PMID:23813599

  11. Multiscale geometric modeling of macromolecules II: Lagrangian representation.

    PubMed

    Feng, Xin; Xia, Kelin; Chen, Zhan; Tong, Yiying; Wei, Guo-Wei

    2013-09-15

    Geometric modeling of biomolecules plays an essential role in the conceptualization of biolmolecular structure, function, dynamics, and transport. Qualitatively, geometric modeling offers a basis for molecular visualization, which is crucial for the understanding of molecular structure and interactions. Quantitatively, geometric modeling bridges the gap between molecular information, such as that from X-ray, NMR, and cryo-electron microscopy, and theoretical/mathematical models, such as molecular dynamics, the Poisson-Boltzmann equation, and the Nernst-Planck equation. In this work, we present a family of variational multiscale geometric models for macromolecular systems. Our models are able to combine multiresolution geometric modeling with multiscale electrostatic modeling in a unified variational framework. We discuss a suite of techniques for molecular surface generation, molecular surface meshing, molecular volumetric meshing, and the estimation of Hadwiger's functionals. Emphasis is given to the multiresolution representations of biomolecules and the associated multiscale electrostatic analyses as well as multiresolution curvature characterizations. The resulting fine resolution representations of a biomolecular system enable the detailed analysis of solvent-solute interaction, and ion channel dynamics, whereas our coarse resolution representations highlight the compatibility of protein-ligand bindings and possibility of protein-protein interactions. PMID:23813599

  12. Peridynamic Multiscale Finite Element Methods

    SciTech Connect

    Costa, Timothy; Bond, Stephen D.; Littlewood, David John; Moore, Stan Gerald

    2015-12-01

    The problem of computing quantum-accurate design-scale solutions to mechanics problems is rich with applications and serves as the background to modern multiscale science research. The prob- lem can be broken into component problems comprised of communicating across adjacent scales, which when strung together create a pipeline for information to travel from quantum scales to design scales. Traditionally, this involves connections between a) quantum electronic structure calculations and molecular dynamics and between b) molecular dynamics and local partial differ- ential equation models at the design scale. The second step, b), is particularly challenging since the appropriate scales of molecular dynamic and local partial differential equation models do not overlap. The peridynamic model for continuum mechanics provides an advantage in this endeavor, as the basic equations of peridynamics are valid at a wide range of scales limiting from the classical partial differential equation models valid at the design scale to the scale of molecular dynamics. In this work we focus on the development of multiscale finite element methods for the peridynamic model, in an effort to create a mathematically consistent channel for microscale information to travel from the upper limits of the molecular dynamics scale to the design scale. In particular, we first develop a Nonlocal Multiscale Finite Element Method which solves the peridynamic model at multiple scales to include microscale information at the coarse-scale. We then consider a method that solves a fine-scale peridynamic model to build element-support basis functions for a coarse- scale local partial differential equation model, called the Mixed Locality Multiscale Finite Element Method. Given decades of research and development into finite element codes for the local partial differential equation models of continuum mechanics there is a strong desire to couple local and nonlocal models to leverage the speed and state of the

  13. Study of magnetic properties in ball-milled MnFeCo

    NASA Astrophysics Data System (ADS)

    Cornejo, D. R.; Padrón Hernández, E.; Rechenberg, H. R.; Azevedo, A.; Rezende, S. M.

    2004-05-01

    A study of the magnetic properties in mechanical alloyed nanocrystalline MnO+FeCo was carried out. As-milled and annealed samples show a noticeable improvement of the coercivity, even at room temperature. A strong effect over the spin wave stiffness constant of the ferromagnetic α -FeCo, probably induced by the antiferromagnetic ordering of the MnO around to 120K (the Néel temperature of MnO) was observed.

  14. Varistors prepared from nanocrystalline powders obtained by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Darvishi Alamdari, Houshang

    2001-12-01

    ZnO based varistors, which protect electrical equipment against overvoltages, have been used for several years. They are electrical devices whose resistance varies non-linearly with the applied voltage. The material in these devices has two main components: conducting ZnO grains surrounded by non-conducting Bi2O3-rich grain boundaries. At low voltages, the electrons are trapped in the conducting parts and the material acts as an insulator. When the voltage crosses the so-called breakdown voltage, the electrons overcome the potential barriers and the material becomes a good conductor. The current can then be conducted to the earth instead of damaging the electrical equipment. Typical commercial varistors use conventional micron size ZnO particles as starting material and the final grain size, after sintering at around 1200°C for 2--5 hours, is of the order of 10 mum. The corresponding breakdown voltage is between 1 and 2 kV/cm. The smaller the grain size, the higher the breakdown voltage. Our main contribution in this work is to use nanocrystalline starting powders to fabricate varistors with very high breakdown voltages. The nanocrystalline powders, with very fine grains, have a very large sintering potential which allows to consolidate these materials at lower temperatures and to avoid grain growth. We studied the consolidation phenomenon of these powders in order to produce solids with high density, the consolidation of nanocrystalline powders being not the same as that of conventional powders. In this phase, the effect of milling time and media, green density, heating rate, sintering time and temperature, hot pressing, etc. was studied. Based on the results, a consolidation mechanism was proposed. We also investigated systematically the effect of different additives, such as Bi2O3, Sb 2O3, MnO2, SiO2, Al2O 3, Nb2O5, etc., on the electrical properties and performance of the nanovaristors. Using optimized composition and fabrication parameters, devices with breakdown voltage (>15 kV/cm) larger by one order of magnitude than that of conventional varistors, were made. These devices have a very fine and homogeneous microstructure with a mean grain size smaller than 2 mum. The time and temperature of sintering was reduced to 1000°C and 1 min., respectively, and the density of sintered parts was slightly higher than that of commercial varistors.

  15. Survival of the Fittest: Competitive Co-crystal Reactions in the Ball Mill.

    PubMed

    Fischer, Franziska; Joester, Maike; Rademann, Klaus; Emmerling, Franziska

    2015-10-12

    The driving forces triggering the formation of co-crystals under milling conditions were investigated by using a set of multicomponent competitive milling reactions. In these reactions, different active pharmaceutical ingredients were ground together with a further compound acting as coformer. The study was based on new co-crystals including the coformer anthranilic acid. The results of the competitive milling reactions indicate that the formation of co-crystals driven by intermolecular recognition are influenced and inhibited by kinetic aspects including the formation of intermediates and the stability of the reactants. PMID:26332316

  16. Chemical reactions of metal powders with organic and inorganic liquids during ball milling

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    Chromium and/or nickel powders were milled in metal chlorides and in organic liquids representative of various functional groups. The powders always reacted with the liquid and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 weight percent. Compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid.

  17. A Mössbauer effect study of ball-milled strontium ferrite

    NASA Astrophysics Data System (ADS)

    Wu, E.; Campbell, S. J.; Kaczmarek, W. A.

    1998-01-01

    The effects of milling SrFe 12O 19 in air and vacuum for 800 h have been investigated by X-ray diffraction and Mössbauer effect spectroscopy measurements. Different levels of structural disorder along with partial decomposition of SrFe 12O 19 to nanocrystalline grains of haematite, α-Fe 2O 3, and magnetite, Fe 3O 4, are obtained for the air and vacuum milling. Superparamagnetic relaxation effects due to the fine particles produced on milling are observed for a significant fraction ( ˜ 10% air milled, ˜ 30% vacuum milled) of the milled samples.

  18. HPMC as a potential enhancer of nimodipine biopharmaceutical properties via ball-milled solid dispersions.

    PubMed

    Riekes, Manoela Klüppel; Kuminek, Gislaine; Rauber, Gabriela Schneider; de Campos, Carlos Eduardo Maduro; Bortoluzzi, Adailton João; Stulzer, Hellen Karine

    2014-01-01

    The poor solubility of drugs remains one of the most challenging aspects of formulation development. Aiming at improving the biopharmaceutical limitations of the calcium channel blocker nimodipine, the development of solid dispersions is proposed herein. Three different proportions of nimodipine:HPMC were tested and all of them generated amorphous solid dispersions. Improvements of up 318% in the solubility and a 4-fold increase in the dissolution rate of nimodipine were achieved. Stability studies conducted over 90 days in a desiccator indicated that the initial characteristic of the formulations were maintained. However, at 40 °C/75% RH recrystallization was observed for solid dispersions with 70 and 80% of HPMC, whilst the formulation composed of 90% of the carrier remained amorphous. The increase in the stability observed when the HPMC concentration was increased from 70 to 90% in the solid dispersions was attributed to the dilution mechanism. PMID:24274533

  19. Polymorphic form of piroxicam influences the performance of amorphous material prepared by ball-milling.

    PubMed

    Naelapää, Kaisa; Boetker, Johan Peter; Veski, Peep; Rantanen, Jukka; Rades, Thomas; Kogermann, Karin

    2012-06-15

    The objective of this study was to investigate the influence of the starting solid state form of piroxicam (anhydrate form I: PRXAH I vs form II: PRXAH II) on the properties of the resulting amorphous material. The second objective was to obtain further insight into the impact of critical factors like thermal stress, dissolution medium and storage conditions on the thermal behavior, solid state transformations and physical stability of amorphous materials. For analysis differential scanning calorimetry (DSC), Raman spectroscopy and X-ray powder diffractometry (XRPD) were used. Pair-wise distribution function (PDF) analysis of the XRPD data was performed. PDF analysis indicated that the recrystallization behavior of amorphous samples was influenced by the amount of residual order in the samples. The recrystallization behavior of amorphous samples prepared from PRXAH I showed similarity to the starting material, whereas the recrystallization behavior of amorphous samples prepared from PRXAH II resembled to that of the PRX form III (PRXAH III). Multivariate data analysis (MVDA) helped to identify that the influence of storage time and temperature was more pronounced in the case of amorphous PRX prepared from PRXAH I. Furthermore, the wet slurry experiments with amorphous materials revealed the recrystallization of amorphous material as PRXMH in the biorelevant medium. PMID:22433471

  20. Optimizing particle size reduction of biochar using a planetary ball mill

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With world demand for fossil fuels consistently growing, reducing our dependence on petroleum products is a necessary strategy. Our research group is currently studying the feasibility of biochar as rubber composite filler. If biochar can be used as a partial or complete substitute for carbon black ...

  1. Dependence of rates of breakage on fines content in wet ball mill grinding

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Anirban

    The following research fundamentally deals with the cause and implications of nonlinearities in breakage rates of materials in wet grinding systems. The innate dependence of such nonlinearities on fines content and the milling environment during wet grinding operations is also tested and observed. Preferential breakage of coarser size fractions as compared to the finer size fractions in a particle population were observed and discussed. The classification action of the pulp was deemed to be the probable cause for such a peculiarity. Ores with varying degrees of hardness and brittleness were used for wet grinding experiments, primarily to test the variations in specific breakage rates as a function of varying hardness. For this research, limestone, quartzite, and gold ore were used. The degree of hardness is of the order of: limestone, quartzite, gold ore. Selection and breakage function parameters were determined in the course of this research. Functional forms of these expressions were used to compare experimentally derived parameter estimates. Force-fitting of parameters was not done in order to examine the realtime behavior of particle populations in wet grinding systems. Breakage functions were established as being invariant with respect to such operating variables like ball load, mill speed, particle load, and particle size distribution of the mill. It was also determined that specific selection functions were inherently dependent on the particle size distribution in wet grinding systems. Also, they were consistent with inputs of specific energy, according to grind time. Nonlinearity trends were observed for 1st order specific selection functions which illustrated variations in breakage rates with incremental inputs of grind time and specific energy. A mean particle size called the fulcrum was noted below which the nonlinearities in the breakage trends were observed. This magnitude of the fulcrum value varied with percent solids and slurry filling, indicating that breakage rates were being influenced by the milling environment as a whole. Primarily, there was always an increase in the breakage rates of coarser fractions with an increase in the amount of fines in the particle population. Consequently, the breakage rates of the finer size fractions were observed to decrease with an increase in grind time. Similar trends were noticed for 2nd order specific selection functions, where incremental inputs of specific energy were provided to observe realtime trends in the nonlinearity of breakage rates closely. Although the breakage rates for coarser size fractions increase with an increase in the amount of fines, the nature of nonlinearities varied with extended grind times. 1st order and 2nd order energy-specific breakage rates were observed to notice the variation in trends with extended grind times. Implications of such nonlinearities in specific breakage rates of various materials were tested on predictive simulation techniques, using the normalized linear population balance model and compared with an incremental methodology of specific energy input.

  2. Implementing Multiscale Fluid Simulations using Multiscale Universal Interface

    NASA Astrophysics Data System (ADS)

    Tang, Yu-Hang; Kudo, Shuhei; Bian, Xin; Li, Zhen; Karniadakis, George; Crunch Team

    2015-11-01

    The power of multiscale fluid simulations lies in its ability to recover a hierarchical levels of details by choreographing multiple solvers, thus extending the length and time scale accessible given a fixed amount of computing power. However, practical difficulties frequently arise when stitching together solvers which were not designed to be coupled, and would often result in tedious and unsustainable coding effort. The Multiscale Universal Interface (MUI) aims to solve this problem by exposing a small set of generalized programming interfaces that can be dropped into existing solvers with minimal intrusion. Three deployment cases will be given for demonstrating real-world applications of MUI. In the first case we used MUI to implement simulations of polymer-grafted surface in flow using Smoothed Particle Hydrodynamics/Dissipative Particle Dynamics (SPH/DPD) and state variable coupling. In the second case we constructed coupled DPD/Finite Element Method (FEM) simulation of conjugate heat transfer in heterogeneous coolant. In the third case we built hybrid DPD/molecular dynamics (MD) simulations by blending the forces on atoms at interface regions. Supported by the DOE Collaboratory on Mathematics for Mesoscopic Modeling of Materials (CM4) and AFOSR FA9550-12-1-0463. Computer hours at ORNL allocated through INCITE BIP118 and DD102.

  3. Multiscale hierarchical support vector clustering

    NASA Astrophysics Data System (ADS)

    Hansen, Michael Saas; Holm, David Alberg; Sjöstrand, Karl; Ley, Carsten Dan; Rowland, Ian John; Larsen, Rasmus

    2008-03-01

    Clustering is the preferred choice of method in many applications, and support vector clustering (SVC) has proven efficient for clustering noisy and high-dimensional data sets. A method for multiscale support vector clustering is demonstrated, using the recently emerged method for fast calculation of the entire regularization path of the support vector domain description. The method is illustrated on artificially generated examples, and applied for detecting blood vessels from high resolution time series of magnetic resonance imaging data. The obtained results are robust while the need for parameter estimation is reduced, compared to support vector clustering.

  4. Multi-scale Shock Technique

    Energy Science and Technology Software Center (ESTSC)

    2009-08-01

    The code to be released is a new addition to the LAMMPS molecular dynamics code. LAMMPS is developed and maintained by Sandia, is publicly available, and is used widely by both natioanl laboratories and academics. The new addition to be released enables LAMMPS to perform molecular dynamics simulations of shock waves using the Multi-scale Shock Simulation Technique (MSST) which we have developed and has been previously published. This technique enables molecular dynamics simulations of shockmore » waves in materials for orders of magnitude longer timescales than the direct, commonly employed approach.« less

  5. Nanosized copper ferrite materials: Mechanochemical synthesis and characterization

    SciTech Connect

    Manova, Elina; Tsoncheva, Tanya; Paneva, Daniela; Popova, Margarita; Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan

    2011-05-15

    Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Moessbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe{sub 2}O{sub 3}. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium. -- Graphical abstract: It is demonstrated that the catalytic behavior of the obtained copper ferrites depends not only on their initial phase composition, but on the concomitant phase transformations by the influence of the reaction medium. Display Omitted Highlights: {yields} Two-step co-precipitation-ball-milling procedure for copper ferrites preparation. {yields} The phase composition of ferrites depends on the milling duration. {yields} Ferrites transforms under the reaction medium, which affects their catalytic behavior. {yields} Ferrites decompose to magnetite and carbides during methanol decomposition. {yields} Agglomeration and further crystallization of ferrite occur during toluene oxidation.

  6. Towards a Multiscale Approach to Cybersecurity Modeling

    SciTech Connect

    Hogan, Emilie A.; Hui, Peter SY; Choudhury, Sutanay; Halappanavar, Mahantesh; Oler, Kiri J.; Joslyn, Cliff A.

    2013-11-12

    We propose a multiscale approach to modeling cyber networks, with the goal of capturing a view of the network and overall situational awareness with respect to a few key properties--- connectivity, distance, and centrality--- for a system under an active attack. We focus on theoretical and algorithmic foundations of multiscale graphs, coming from an algorithmic perspective, with the goal of modeling cyber system defense as a specific use case scenario. We first define a notion of \\emph{multiscale} graphs, in contrast with their well-studied single-scale counterparts. We develop multiscale analogs of paths and distance metrics. As a simple, motivating example of a common metric, we present a multiscale analog of the all-pairs shortest-path problem, along with a multiscale analog of a well-known algorithm which solves it. From a cyber defense perspective, this metric might be used to model the distance from an attacker's position in the network to a sensitive machine. In addition, we investigate probabilistic models of connectivity. These models exploit the hierarchy to quantify the likelihood that sensitive targets might be reachable from compromised nodes. We believe that our novel multiscale approach to modeling cyber-physical systems will advance several aspects of cyber defense, specifically allowing for a more efficient and agile approach to defending these systems.

  7. Multiscale analysis of neural spike trains.

    PubMed

    Ramezan, Reza; Marriott, Paul; Chenouri, Shojaeddin

    2014-01-30

    This paper studies the multiscale analysis of neural spike trains, through both graphical and Poisson process approaches. We introduce the interspike interval plot, which simultaneously visualizes characteristics of neural spiking activity at different time scales. Using an inhomogeneous Poisson process framework, we discuss multiscale estimates of the intensity functions of spike trains. We also introduce the windowing effect for two multiscale methods. Using quasi-likelihood, we develop bootstrap confidence intervals for the multiscale intensity function. We provide a cross-validation scheme, to choose the tuning parameters, and study its unbiasedness. Studying the relationship between the spike rate and the stimulus signal, we observe that adjusting for the first spike latency is important in cross-validation. We show, through examples, that the correlation between spike trains and spike count variability can be multiscale phenomena. Furthermore, we address the modeling of the periodicity of the spike trains caused by a stimulus signal or by brain rhythms. Within the multiscale framework, we introduce intensity functions for spike trains with multiplicative and additive periodic components. Analyzing a dataset from the retinogeniculate synapse, we compare the fit of these models with the Bayesian adaptive regression splines method and discuss the limitations of the methodology. Computational efficiency, which is usually a challenge in the analysis of spike trains, is one of the highlights of these new models. In an example, we show that the reconstruction quality of a complex intensity function demonstrates the ability of the multiscale methodology to crack the neural code. PMID:23996238

  8. Analysis of the effects of different machining processes on sealing using multiscale topography

    NASA Astrophysics Data System (ADS)

    Deltombe, Raphael; Bigerelle, Maxence; Jourani, Abdeljalil

    2016-03-01

    This study characterizes seal performance using a multiscale analysis of surface topography. The performance of two surface morphologies is compared: the first one is obtained with machining only and leads to leakage while the second one is obtained with machining and superfinishing and prevents leakage. It is shown that conventional roughness analysis does not enable to identify the differences between both surfaces. Only the use of a new parameter, the order parameter, and the use of a multiscale analysis of surfaces enable to distinguish the studied surfaces and to identify leakage causes. These causes are checked using a numerical contact simulation. It is shown that microroughness plays a major role in leakage.

  9. Initial characterization of a highly contaminated high explosives outfall in preparation for in situ bioremediation

    SciTech Connect

    Betty A. Strietelmeier; Patrick J. Coyne; Patricia A. Leonard; W. Lamar Miller; Jerry R. Brian

    1999-12-01

    In situ bioremediation is a viable, cost-effective treatment for environmental contamination of many kinds. The feasibility of using biological techniques to remediate soils contaminated with high explosives (HE) requires laboratory evaluation before proceeding to a larger scale field operation. Laboratory investigations have been conducted at pilot scale which indicate that an anaerobic process could be successful at reducing levels of HE, primarily HMX, RDX and TNT, in contaminated soils. A field demonstration project has been designed to create an anaerobic environment for the degradation of HE materials. The first step in this project, initial characterization of the test area, was conducted and is the subject of this report. The levels of HE compounds found in the samples from the test area were higher than the EPA Method 8330 was able to extract without subsequent re-precipitation; therefore, a new method was developed using a superior extractant system. The test area sampling design was relatively simple as one might expect in an initial characterization. A total of 60 samples were each removed to a depth of 4 inches using a 1 inch diameter corer. The samples were spaced at relatively even intervals across a 20 foot cross-section through the middle of four 7-foot-long adjacent plots which are designed to be a part of an in situ bioremediation experiment. Duplicate cores were taken from each location for HE extraction and analysis in order to demonstrate and measure the heterogeneity of the contamination. Each soil sample was air dried and ball-milled to provide a homogeneous solid for extraction and analysis. Several samples had large consolidated pieces of what appeared to be solid HE. These were not ball-milled due to safety concerns, but were dissolved and the solutions were analyzed. The new extraction method was superior in that results obtained for several of the contaminants were up to 20 times those obtained with the EPA extraction method. The

  10. Synthesis and characterization of Bi-doped Mg{sub 2}Si thermoelectric materials

    SciTech Connect

    Fiameni, S.; Battiston, S.; Boldrini, S.; Famengo, A.; Agresti, F.; Barison, S.; Fabrizio, M.

    2012-09-15

    The Mg{sub 2}Si-based alloys are promising candidates for thermoelectric energy conversion for the middle high range of temperature. They are very attractive as they could replace lead-based compounds due to their low cost and non toxicity. They could also result in thermoelectric generator weight reduction (a key feature for the automotive application field). The high value of thermal conductivity of the silicide-based materials could be reduced by increasing the phonon scattering in the presence of nanosized crystalline grains without heavily interfering with the electrical conductivity of the thermoelectric material. Nanostructured materials were obtained under inert atmosphere through ball milling, thermal treatment and spark plasma sintering processes. In particular, the role of several bismuth doping amounts in Mg{sub 2}Si were investigated (Mg{sub 2}Si:Bi=1:x for x=0.01, 0.02 and 0.04 M ratio). The morphology, the composition and the structure of the samples were characterized by FE-SEM, EDS and XRD analyses after each process step. Moreover, the Seebeck coefficient analyses at high temperature and the electrical and thermal conductivity of the samples are presented in this work. The nanostructuring processes were affect by the MgO amount increase which influenced the thermoelectric properties of the samples mainly by reducing the electrical conductivity. With the aim of further increasing the scattering phenomena by interface or boundary effect, carbon nanostructures named Single Wall Carbon Nanohorns were added to the Mg{sub 2}Si in order to produce a nanocomposite material. The influence of the nanostructured filler on the thermoelectric material properties is also discussed. - Graphical abstract: Figure of merit (ZT) of Bi-doped samples and undoped Mg{sub 2}Si. A maximum ZT value of 0.39 at 600 Degree-Sign C was obtained for the nanocomposite material obtained adding Single Wall Carbon Nanohorns to the Bi 0.02 at% doped silicide. Highlights: Black

  11. Expected Navigation Flight Performance for the Magnetospheric Multiscale (MMS) Mission

    NASA Technical Reports Server (NTRS)

    Olson, Corwin; Wright, Cinnamon; Long, Anne

    2012-01-01

    The Magnetospheric Multiscale (MMS) mission consists of four formation-flying spacecraft placed in highly eccentric elliptical orbits about the Earth. The primary scientific mission objective is to study magnetic reconnection within the Earth s magnetosphere. The baseline navigation concept is the independent estimation of each spacecraft state using GPS pseudorange measurements (referenced to an onboard Ultra Stable Oscillator) and accelerometer measurements during maneuvers. State estimation for the MMS spacecraft is performed onboard each vehicle using the Goddard Enhanced Onboard Navigation System, which is embedded in the Navigator GPS receiver. This paper describes the latest efforts to characterize expected navigation flight performance using upgraded simulation models derived from recent analyses.

  12. Multi-scale statistical analysis of coronal solar activity

    DOE PAGESBeta

    Gamborino, Diana; del-Castillo-Negrete, Diego; Martinell, Julio J.

    2016-07-08

    Multi-filter images from the solar corona are used to obtain temperature maps that are analyzed using techniques based on proper orthogonal decomposition (POD) in order to extract dynamical and structural information at various scales. Exploring active regions before and after a solar flare and comparing them with quiet regions, we show that the multi-scale behavior presents distinct statistical properties for each case that can be used to characterize the level of activity in a region. Information about the nature of heat transport is also to be extracted from the analysis.

  13. Multi-scale statistical analysis of coronal solar activity

    NASA Astrophysics Data System (ADS)

    Gamborino, Diana; del-Castillo-Negrete, Diego; Martinell, Julio J.

    2016-07-01

    Multi-filter images from the solar corona are used to obtain temperature maps that are analyzed using techniques based on proper orthogonal decomposition (POD) in order to extract dynamical and structural information at various scales. Exploring active regions before and after a solar flare and comparing them with quiet regions, we show that the multi-scale behavior presents distinct statistical properties for each case that can be used to characterize the level of activity in a region. Information about the nature of heat transport is also to be extracted from the analysis.

  14. A stochastic multiscale framework for modeling flow through random heterogeneous porous media

    SciTech Connect

    Ganapathysubramanian, B.; Zabaras, N.

    2009-02-01

    Flow through porous media is ubiquitous, occurring from large geological scales down to the microscopic scales. Several critical engineering phenomena like contaminant spread, nuclear waste disposal and oil recovery rely on accurate analysis and prediction of these multiscale phenomena. Such analysis is complicated by inherent uncertainties as well as the limited information available to characterize the system. Any realistic modeling of these transport phenomena has to resolve two key issues: (i) the multi-length scale variations in permeability that these systems exhibit, and (ii) the inherently limited information available to quantify these property variations that necessitates posing these phenomena as stochastic processes. A stochastic variational multiscale formulation is developed to incorporate uncertain multiscale features. A stochastic analogue to a mixed multiscale finite element framework is used to formulate the physical stochastic multiscale process. Recent developments in linear and non-linear model reduction techniques are used to convert the limited information available about the permeability variation into a viable stochastic input model. An adaptive sparse grid collocation strategy is used to efficiently solve the resulting stochastic partial differential equations (SPDEs). The framework is applied to analyze flow through random heterogeneous media when only limited statistics about the permeability variation are given.

  15. Multiscale and cross entropy analysis of auroral and polar cap indices during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Gopinath, Sumesh; Prince, P. R.

    2016-01-01

    In order to improve general monoscale information entropy methods like permutation and sample entropy in characterizing the irregularity of complex magnetospheric system, it is necessary to extend these entropy metrics to a multiscale paradigm. We propose novel multiscale and cross entropy method for the analysis of magnetospheric proxies such as auroral and polar cap indices during geomagnetic disturbance times. Such modified entropy metrics are certainly advantageous in classifying subsystems such as individual contributions of auroral electrojets and field aligned currents to high latitude magnetic perturbations during magnetic storm and polar substorm periods. We show that the multiscale entropy/cross entropy of geomagnetic indices vary with scale factor. These variations can be attributed to changes in multiscale dynamical complexity of non-equilibrium states present in the magnetospheric system. These types of features arise due to imbalance in injection and dissipation rates of energy with variations in magnetospheric response to solar wind. We also show that the multiscale entropy values of time series decrease during geomagnetic storm times which reveals an increase in temporal correlations as the system gradually shifts to a more orderly state. Such variations in entropy values can be interpreted as the signature of dynamical phase transitions which arise at the periods of geomagnetic storms and substorms that confirms several previously found results regarding emergence of cooperative dynamics, self-organization and non-Markovian nature of magnetosphere during disturbed periods.

  16. A Posteriori Analysis of Adaptive Multiscale Operator Decomposition Methods for Multiphysics Problems

    SciTech Connect

    Donald Estep; Michael Holst; Simon Tavener

    2010-02-08

    This project was concerned with the accurate computational error estimation for numerical solutions of multiphysics, multiscale systems that couple different physical processes acting across a large range of scales relevant to the interests of the DOE. Multiscale, multiphysics models are characterized by intimate interactions between different physics across a wide range of scales. This poses significant computational challenges addressed by the proposal, including: (1) Accurate and efficient computation; (2) Complex stability; and (3) Linking different physics. The research in this project focused on Multiscale Operator Decomposition methods for solving multiphysics problems. The general approach is to decompose a multiphysics problem into components involving simpler physics over a relatively limited range of scales, and then to seek the solution of the entire system through some sort of iterative procedure involving solutions of the individual components. MOD is a very widely used technique for solving multiphysics, multiscale problems; it is heavily used throughout the DOE computational landscape. This project made a major advance in the analysis of the solution of multiscale, multiphysics problems.

  17. Multi-scale surface texture to improve blue response of nanoporous black silicon solar cells

    NASA Astrophysics Data System (ADS)

    Toor, Fatima; Branz, Howard M.; Page, Matthew R.; Jones, Kim M.; Yuan, Hao-Chih

    2011-09-01

    We characterize the optical and carrier-collection physics of multi-scale textured p-type black Si solar cells with conversion efficiency of 17.1%. The multi-scale texture is achieved by combining density-graded nanoporous layer made by metal-assisted etching with micron-scale pyramid texture. We found that (1) reducing the thickness of nanostructured Si layer improves the short-wavelength spectral response and (2) multi-scale texture permits thinning of the nanostructured layer while maintaining low surface reflection. We have reduced the nanostructured layer thickness by 60% while retaining a solar-spectrum-averaged black Si reflectance of less than 2%. Spectral response at 450 nm has improved from 57% to 71%.

  18. Irreversible thermodynamics in multiscale stochastic dynamical systems

    NASA Astrophysics Data System (ADS)

    Santillán, Moisés; Qian, Hong

    2011-04-01

    This work extends the results of a recently developed theory of a rather complete thermodynamic formalism for discrete-state, continuous-time Markov processes with and without detailed balance. We investigate whether and in what way the thermodynamic structure is invariant in a multiscale stochastic system, that is, whether the relations between thermodynamic functions of state and process variables remain unchanged when the system is viewed at different time scales and resolutions. Our results show that the dynamics on a fast time scale contribute an entropic term to the internal energy function uS(x) for the slow dynamics. Based on the conditional free energy uS(x), we can then treat the slow dynamics as if the fast dynamics is nonexistent. Furthermore, we show that the free energy, which characterizes the spontaneous organization in a system without detailed balance, is invariant with or without the fast dynamics: The fast dynamics is assumed to reach stationarity instantaneously on the slow time scale; it has no effect on the system’s free energy. The same cannot be said for the entropy and the internal energy, both of which contain the same contribution from the fast dynamics. We also investigate the consequences of time-scale separation in connection to the concepts of quasi-stationarity and steady adiabaticity introduced in the phenomenological steady-state thermodynamics.

  19. Magnetotellurics as a multiscale geophysical exploration method

    NASA Astrophysics Data System (ADS)

    Carbonari, Rolando; D'Auria, Luca; Di Maio, Rosa; Petrillo, Zaccaria

    2016-04-01

    Magnetotellurics (MT) is a geophysical method based on the use of natural electromagnetic signals to define subsurface electrical resistivity structure through electromagnetic induction. MT waves are generated in the Earth's atmosphere and magnetosphere by a range of physical processes, such as magnetic storms, micropulsations, lightning activity. Since the underground MT wave propagation is of diffusive type, the longer is the wavelength (i.e. the lower the wave frequency) the deeper will be the propagation depth. Considering the frequency band commonly used in MT prospecting (10-4 Hz to 104 Hz), the investigation depth ranges from few hundred meters to hundreds of kilometers. This means that magnetotellurics is inherently a multiscale method and, thus, appropriate for applications at different scale ranging from aquifer system characterization to petroleum and geothermal research. In this perspective, the application of the Wavelet transform to the MT data analysis could represent an excellent tool to emphasize characteristics of the MT signal at different scales. In this note, the potentiality of such an approach is studied. In particular, we show that the use of a Discrete Wavelet (DW) decomposition of measured MT time-series data allows to retrieve robust information about the subsoil resistivity over a wide range of spatial (depth) scales, spanning up to 5 orders of magnitude. Furthermore, the application of DWs to MT data analysis has proven to be a flexible tool for advanced data processing (e.g. non-linear filtering, denoising and clustering).

  20. Irreversible thermodynamics in multiscale stochastic dynamical systems.

    PubMed

    Santillán, Moisés; Qian, Hong

    2011-04-01

    This work extends the results of a recently developed theory of a rather complete thermodynamic formalism for discrete-state, continuous-time Markov processes with and without detailed balance. We investigate whether and in what way the thermodynamic structure is invariant in a multiscale stochastic system, that is, whether the relations between thermodynamic functions of state and process variables remain unchanged when the system is viewed at different time scales and resolutions. Our results show that the dynamics on a fast time scale contribute an entropic term to the internal energy function u(S)(x) for the slow dynamics. Based on the conditional free energy u(S)(x), we can then treat the slow dynamics as if the fast dynamics is nonexistent. Furthermore, we show that the free energy, which characterizes the spontaneous organization in a system without detailed balance, is invariant with or without the fast dynamics: The fast dynamics is assumed to reach stationarity instantaneously on the slow time scale; it has no effect on the system's free energy. The same cannot be said for the entropy and the internal energy, both of which contain the same contribution from the fast dynamics. We also investigate the consequences of time-scale separation in connection to the concepts of quasi-stationarity and steady adiabaticity introduced in the phenomenological steady-state thermodynamics. PMID:21599138

  1. Microfluidic assembly of multiscale soft materials

    NASA Astrophysics Data System (ADS)

    Leng, Lian; Guenther, Axel

    2010-11-01

    The vast majority of materials found in nature are characterized by length scales that span several orders of magnitude. Material properties such as porosity, permeability and elasticity are therefore locally and directionally tuned to their (biological) function and adapted to local environmental conditions. We use a massively scaled microfluidic approach to synthetically define multiscale complex fluids and soft materials with precisely tunable, non-isentropic bulk properties. Two or more fluids are separately introduced to the device that consists of fifteen vertically bonded and fluidically connected substrate layers, and guided to an exit section that either consists of 23 equidistantly spaced channels or a 23 x 15 channel array. The flow rates through individual channels are computer-controlled. Upon entering a reservoir in a flow-focusing configuration, a spatially organized fluid with characteristic length scales of 250 microns and 10 mm was defined, and retained via a chemical reaction. To illustrate different soft material morphologies in one, two or three directions, we demonstrate the formation of isolated fibers (1D); planar graded and barcoded materials (2D); graded bulk materials and perfusable matrices (3D).

  2. Sublimation-Condensation of Multiscale Tellurium Structures

    SciTech Connect

    Riley, Brian J.; Johnson, Bradley R.; Schaef, Herbert T.; Sundaram, S. K.

    2013-03-11

    This paper presents a simple technique for making tellurium (Te) nano and microtubes of widely varying dimensions with Multi-Scale Processing (MSP). In this process, the Te metal is placed in a reaction vessel (e.g., borosilicate or fused quartz), the vessel is evacuated, and then sealed under vacuum with a torch. The vessel is heat-treated in a temperature gradient where a portion of the tube that can also contain an additional substrate, is under a decreasing temperature gradient. Scanning and transmission electron microscopies have shown that multifaceted crystalline tubes have been formed extending from nano- up to micron-scale with diameters ranging from 51.2 ± 5.9 to 1042 ± 134 nm between temperatures of 157 and 224 °C, respectively. One-dimensional tubular features are seen at lower temperatures, while three-dimensional features, at the higher temperatures. These features have been characterized with X-ray diffraction and found to be trigonal Te with space group P3121. Our results show that the MSP can adequately be described using a simple Arrhenius equation.

  3. Multiscale modeling of polyisoprene on graphite

    SciTech Connect

    Pandey, Yogendra Narayan; Brayton, Alexander; Doxastakis, Manolis; Burkhart, Craig; Papakonstantopoulos, George J.

    2014-02-07

    The local dynamics and the conformational properties of polyisoprene next to a smooth graphite surface constructed by graphene layers are studied by a multiscale methodology. First, fully atomistic molecular dynamics simulations of oligomers next to the surface are performed. Subsequently, Monte Carlo simulations of a systematically derived coarse-grained model generate numerous uncorrelated structures for polymer systems. A new reverse backmapping strategy is presented that reintroduces atomistic detail. Finally, multiple extensive fully atomistic simulations with large systems of long macromolecules are employed to examine local dynamics in proximity to graphite. Polyisoprene repeat units arrange close to a parallel configuration with chains exhibiting a distribution of contact lengths. Efficient Monte Carlo algorithms with the coarse-grain model are capable of sampling these distributions for any molecular weight in quantitative agreement with predictions from atomistic models. Furthermore, molecular dynamics simulations with well-equilibrated systems at all length-scales support an increased dynamic heterogeneity that is emerging from both intermolecular interactions with the flat surface and intramolecular cooperativity. This study provides a detailed comprehensive picture of polyisoprene on a flat surface and consists of an effort to characterize such systems in atomistic detail.

  4. Toward a Multiscale Approach for Geodynamo Models

    NASA Astrophysics Data System (ADS)

    Marcotte, F.; Dormy, E.

    2014-12-01

    The generation of the Earth's magnetic field by dynamo action in the liquid iron core is modeled by a large set of coupled, non-linear partial differential equations. Numerical models presently involve direct discretization of the geodynamo equations and allow to produce axial dipolar magnetic fields that are qualitatively comparable to the Earth's one, but whose dynamics remain considerably remote from the geophysical regime. Indeed, due to the extreme values of the dimensionless numbers characterizing the Earth's core dynamics, the relevant regime remains far beyond the reach of direct numerical simulation - so far that one cannot simply rely on the increase in computational power. Simplification of the governing equations is not straightforward. In particular, the importance of return flow from the thin Ekman layers located at the inner core and core-mantle boundaries into the main flow prevents one from purely suppressing the viscous dissipation term in Navier-Stokes equation even in the limiting case where inertia is neglected. Therefore more advanced models are needed, which require prior mathematical treatment of the equations of magnetohydrodynamics. The one-dimensional structure of most viscous and magnetic layers demonstrates the possibility of huge computational savings by means of multiscale techniques. In our approach, asymptotic matching is applied on simplified problems such as the Proudman-Stewartson flow to solve for the viscous shear layers while keeping the mainstream resolved on a coarse grid.

  5. Multiscale Modeling of UHTC: Thermal Conductivity

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Murry, Daw; Squire, Thomas; Bauschlicher, Charles W.

    2012-01-01

    We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network.

  6. NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANOPARTICLE MIXED ALCOHOL CATALYSTS

    SciTech Connect

    Seetala V. Naidu; Upali Siriwardane

    2005-05-24

    We have developed and streamlined the experimental systems: (a) Laser-induced solution deposition (LISD) photosynthesis, ball-milling, and chemical synthesis of Fe, Co, and Cu nanoparticle catalysts; (b) Sol-gel method for mesoporous {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, hybrid alumina/silica granular supports; (c) Three sol-gel/oil-drop catalyst preparation methods to incorporate metal nanoparticles into mesoporous 1 mm granular supports; (d) Low-cost GC-TCD system with hydrogen as carrier gas for the determination of wide spectrum of alkanes produced during the F-T reactions; and (e) Gas-flow reactor and microchannel reactor for fast screening of catalysts. The LISD method could produce Co, Cu, and Fe (5 nm) nanoparticles, but in milligram quantities. We could produce nanoparticles in gram quantities using high-energy ball milling and chemical synthesis methods. Ball milling gave wide particle size distribution compared to the chemical synthesis method that gave almost uniform size ({approx}5 nm) particles. Metal nanoparticles Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe were loaded (2-12 wt%) uniformly into {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, or alumina/silica hybrid supports by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, prior to syngas FT reaction studies. The properties of metal loaded {gamma}-Al{sub 2}O{sub 3} granules were compared for the two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). The effect of solgel supports alumina, silica, and alumina/silica hybrid were examined on catalytic properties. Metal loading efficiencies for pure metal catalysts increased in the order Co, Cu and Fe in agreement with solubility of metal hydroxides. In case of mixed metals, Co and Cu seams to interfere and reduce Fe metal loading when metal nitrate solutions are used. The solubility differences of metal hydroxides would not allow precise control of metal loading. We have overcome this problem by

  7. A framework for multi-scale modelling

    PubMed Central

    Chopard, B.; Borgdorff, Joris; Hoekstra, A. G.

    2014-01-01

    We review a methodology to design, implement and execute multi-scale and multi-science numerical simulations. We identify important ingredients of multi-scale modelling and give a precise definition of them. Our framework assumes that a multi-scale model can be formulated in terms of a collection of coupled single-scale submodels. With concepts such as the scale separation map, the generic submodel execution loop (SEL) and the coupling templates, one can define a multi-scale modelling language which is a bridge between the application design and the computer implementation. Our approach has been successfully applied to an increasing number of applications from different fields of science and technology. PMID:24982249

  8. On multiscale entropy analysis for physiological data

    NASA Astrophysics Data System (ADS)

    Thuraisingham, Ranjit A.; Gottwald, Georg A.

    2006-07-01

    We perform an analysis of cardiac data using multiscale entropy as proposed in Costa et al. [Multiscale entropy analysis of complex physiological time series, Phys. Rev. Lett. 89 (2002) 068102]. We reproduce the signatures of the multiscale entropy for the three cases of young healthy hearts, atrial fibrillation and congestive heart failure. We show that one has to be cautious how to interpret these signatures in terms of the underlying dynamics. In particular, we show that different dynamical systems can exhibit the same signatures depending on the sampling time, and that similar systems may have different signatures depending on the time scales involved. Besides the total amount of data we identify the sampling time, the correlation time and the period of possible nonlinear oscillations as important time scales which have to be involved in a detailed analysis of the signatures of multiscale entropies. We illustrate our ideas with the Lorenz equation as a simple deterministic chaotic system.

  9. Collaborating for Multi-Scale Chemical Science

    SciTech Connect

    William H. Green

    2006-07-14

    Advanced model reduction methods were developed and integrated into the CMCS multiscale chemical science simulation software. The new technologies were used to simulate HCCI engines and burner flames with exceptional fidelity.

  10. Multiscale modelling in immunology: a review.

    PubMed

    Cappuccio, Antonio; Tieri, Paolo; Castiglione, Filippo

    2016-05-01

    One of the greatest challenges in biomedicine is to get a unified view of observations made from the molecular up to the organism scale. Towards this goal, multiscale models have been highly instrumental in contexts such as the cardiovascular field, angiogenesis, neurosciences and tumour biology. More recently, such models are becoming an increasingly important resource to address immunological questions as well. Systematic mining of the literature in multiscale modelling led us to identify three main fields of immunological applications: host-virus interactions, inflammatory diseases and their treatment and development of multiscale simulation platforms for immunological research and for educational purposes. Here, we review the current developments in these directions, which illustrate that multiscale models can consistently integrate immunological data generated at several scales, and can be used to describe and optimize therapeutic treatments of complex immune diseases. PMID:25810307

  11. Multiscale model for pulmonary oxygen uptake and its application to quantify hypoxemia in hepatopulmonary syndrome.

    PubMed

    Chakraborty, Saikat; Balakotaiah, Vemuri; Bidani, Akhil

    2007-01-21

    This paper presents a novel multiscale methodology for quantitative analysis of pulmonary gas exchange. The process of oxygen uptake in the lungs is a complex multiscale process, characterized by multiple time and length scales which are coupled nonlinearly through the processes of diffusion, convection and reaction, and the overall oxygen uptake is significantly influenced by the transport and reaction rate processes at the small-scales. Based on the separation of length scales, we characterize these disparate scales by three representative ones, namely micro (red blood cell), meso (capillary and alveolus) and macro (lung). We start with the fundamental convection-diffusion-reaction (CDR) equation that quantifies transport and reaction rates at each scale and apply spatial averaging techniques to reduce the dimensionality of these models. The resultant low-dimensional models embed each scale hierarchically within the other while retaining the important parameters of the small-scales in the averaged equations, and drastically reduce the computational efforts involved in solving them. We use our multiscale model for pulmonary gas exchange to quantify the oxygen uptake abnormalities in patients with hepatopulmonary syndrome (HPS), a disease which is characterized by coupled abnormalities in multiple length scales. Based on our multiscale modeling, we suggest a strategy to stratify patients with HPS into two categories--those who are oxygen-responsive and those who are oxygen non-responsive with intractable hypoxemia. PMID:16973178

  12. Sliding Wear Properties of HVOF Thermally Sprayed Nylon-11 and Nylon-11/Ceramic Composites on Steel

    NASA Astrophysics Data System (ADS)

    Jackson, L.; Ivosevic, M.; Knight, R.; Cairncross, R. A.

    2007-12-01

    Polymer and polymer/ceramic composite coatings were produced by ball-milling 60 μm Nylon-11 together with nominal 10 vol.% of nano and multiscale ceramic reinforcements and by HVOF spraying these composite feedstocks onto steel substrates to produce semicrystalline micron and nanoscale reinforced polymer matrix composites. Room temperature dry sliding wear performance of pure Nylon-11, Nylon-11 reinforced with 7 nm silica, and multiscale Nylon-11/silica composite coatings incorporating 7-40 nm and 10 μm ceramic particles were characterized using a pin-on-disk tribometer. Coefficient of friction and wear rate were determined as a function of applied load and coating composition. Surface profilometry and scanning electron microscopy were used to characterize and analyze the coatings and wear scars. The pure Nylon-11 coating experienced less wear than the composites due to the occurrence of two additional wear mechanisms: abrasive and fatigue wear.

  13. Multiscale Theory of Dislocation Climb

    NASA Astrophysics Data System (ADS)

    Geslin, Pierre-Antoine; Appolaire, Benoît; Finel, Alphonse

    2015-12-01

    Dislocation climb is a ubiquitous mechanism playing a major role in the plastic deformation of crystals at high temperature. We propose a multiscale approach to model quantitatively this mechanism at mesoscopic length and time scales. First, we analyze climb at a nanoscopic scale and derive an analytical expression of the climb rate of a jogged dislocation. Next, we deduce from this expression the activation energy of the process, bringing valuable insights to experimental studies. Finally, we show how to rigorously upscale the climb rate to a mesoscopic phase-field model of dislocation climb. This upscaling procedure opens the way to large scale simulations where climb processes are quantitatively reproduced even though the mesoscopic length scale of the simulation is orders of magnitude larger than the atomic one.

  14. Multiscale Theory of Dislocation Climb.

    PubMed

    Geslin, Pierre-Antoine; Appolaire, Benoît; Finel, Alphonse

    2015-12-31

    Dislocation climb is a ubiquitous mechanism playing a major role in the plastic deformation of crystals at high temperature. We propose a multiscale approach to model quantitatively this mechanism at mesoscopic length and time scales. First, we analyze climb at a nanoscopic scale and derive an analytical expression of the climb rate of a jogged dislocation. Next, we deduce from this expression the activation energy of the process, bringing valuable insights to experimental studies. Finally, we show how to rigorously upscale the climb rate to a mesoscopic phase-field model of dislocation climb. This upscaling procedure opens the way to large scale simulations where climb processes are quantitatively reproduced even though the mesoscopic length scale of the simulation is orders of magnitude larger than the atomic one. PMID:26765003

  15. Multiscale dynamics in relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Toulouse, Jean; Cai, L.; Pattnaik, R. K.; Boatner, L. A.

    2014-01-01

    The multiscale dynamics of complex oxides is illustrated by pairs of mechanical resonances that are excited in the relaxor ferroelectric K1-xLixTaO3 (KLT). These macroscopic resonances are shown to originate in the collective dynamics of piezoelectric polar nanodomains (PNDs) interacting with the surrounding lattice. Their characteristic Fano lineshapes and rapid evolution with temperature reveal the coherent interplay between the piezoelectric oscillations and orientational relaxations of the PNDs at higher temperature and the contribution of heterophase oscillations near the phase transition. A theoretical model is presented, that describes the evolution of the resonances over the entire temperature range. Similar resonances are observed in other relaxors and must therefore be a common characteristics of these systems.

  16. [Multiscale entropy analysis of electrocardiogram].

    PubMed

    Wang, Jun; Ning, Xinbao; Li, Jin; Ma, Qianli; Xu, Yinlin; Bian, Chunhua

    2007-10-01

    Using the algorithm proposed by Costa M, et al., we studied the multiscale entropy (MSE) of electrocardiogram. The sample entropy (SampEn) of the healthy subjects was found to be higher than that of the subjects with coronary heart disease or myocardial infarction. The healthy subjects' complexity was found to be the highest. The SampEn of the subjects with coronary heart disease was noted to be only slightly higher than that of the subjects with myocardial infarction. These findings show that the complexity of the subjects with coronary heart disease or myocardial infarction is distinctly lower than the complexity of the healthy ones, and the subjects suffereing from coronary heart disease are liable to the onset of myocardial infarction. PMID:18027679

  17. MULTISCALE MODELING OF POLYMER NANOCOMPOSITES

    SciTech Connect

    Maiti, A

    2007-07-16

    Polymer Nanocomposites are an important class of nanomaterials with potential applications including but not limited to structural and cushion materials, electromagnetic and heat shields, conducting plastics, sensors, and catalysts for various chemical and bio processes. Success in most such applications hinges on molecular-level control of structure and assembly, and a deep understanding of how the overall morphology of various components and the interfaces between them affect the composite properties at the macroscale. The length and time-scales associated with such assemblies are prohibitively large for a full atomistic modeling. Instead we adopt a multiscale methodology in which atomic-level interactions between different components of a composite are incorporated into a coarse-grained simulation of the mesoscale morphology, which is then represented on a numerical grid and the macroscopic properties computed using a finite-elements method.

  18. Propagation in multiscale random media

    NASA Astrophysics Data System (ADS)

    Balk, Alexander M.

    2003-10-01

    Many studies consider media with microstructure, which has variations on some microscale, while the macroproperties are under investigation. Sometimes the medium has several microscales, all of them being much smaller than the macroscale. Sometimes the variations on the macroscale are also included, which are taken into account by some procedures, like WKB or geometric optics. What if the medium has variations on all scales from microscale to macroscale? This situation occurs in several practical problems. The talk is about such situations, in particular, passive tracer in a random velocity field, wave propagation in a random medium, Schrödinger equation with random potential. To treat such problems we have developed the statistical near-identity transformation. We find anomalous attenuation of the pulse propagating in a multiscale medium.

  19. A concurrent multiscale micromorphic molecular dynamics

    SciTech Connect

    Li, Shaofan Tong, Qi

    2015-04-21

    In this work, we have derived a multiscale micromorphic molecular dynamics (MMMD) from first principle to extend the (Andersen)-Parrinello-Rahman molecular dynamics to mesoscale and continuum scale. The multiscale micromorphic molecular dynamics is a con-current three-scale dynamics that couples a fine scale molecular dynamics, a mesoscale micromorphic dynamics, and a macroscale nonlocal particle dynamics together. By choosing proper statistical closure conditions, we have shown that the original Andersen-Parrinello-Rahman molecular dynamics is the homogeneous and equilibrium case of the proposed multiscale micromorphic molecular dynamics. In specific, we have shown that the Andersen-Parrinello-Rahman molecular dynamics can be rigorously formulated and justified from first principle, and its general inhomogeneous case, i.e., the three scale con-current multiscale micromorphic molecular dynamics can take into account of macroscale continuum mechanics boundary condition without the limitation of atomistic boundary condition or periodic boundary conditions. The discovered multiscale scale structure and the corresponding multiscale dynamics reveal a seamless transition from atomistic scale to continuum scale and the intrinsic coupling mechanism among them based on first principle formulation.

  20. Nanomechanics and Multiscale Modeling of Sustainable Concretes

    NASA Astrophysics Data System (ADS)

    Zanjani Zadeh, Vahid

    The work presented in this dissertation is aimed to implement and further develop the recent advances in material characterization for porous and heterogeneous materials and apply these advances to sustainable concretes. The studied sustainable concretes were concrete containing fly ash and slag, Kenaf fiber reinforced concrete, and lightweight aggregate concrete. All these cement-based materials can be categorized as sustainable concrete, by achieving concrete with high strength while reducing cement consumption. The nanoindentation technique was used to infer the nanomechanical properties of the active hydration phases in bulk cement paste. Moreover, the interfacial transition zone (ITZ) of lightweight aggregate, normal aggregate, and Kenaf fibers were investigated using nanoindentation and imagine techniques, despite difficulties regarding characterizing this region. Samples were also tested after exposure to high temperature to evaluate the damage mechanics of sustainable concretes. It has been shown that there is a direct correlation between the nature of the nanoscale structure of a cement-based material with its macroscopic properties. This was addressed in two steps in this dissertation: (i) Nanoscale characterization of sustainable cementitious materials to understand the different role of fly ash, slag, lightweight aggregate, and Kenaf fibers on nanoscale (ii) Link the nanoscale mechanical properties to macroscale ones with multiscale modeling. The grid indentation technique originally developed for normal concrete was extended to sustainable concretes with more complex microstructure. The relation between morphology of cement paste materials and submicron mechanical properties, indentation modulus, hardness, and dissipated energy is explained in detail. Extensive experimental and analytical approaches were focused on description of the materials' heterogeneous microstructure as function of their composition and physical phenomenon. Quantitative

  1. A mathematical framework for multiscale science and engineering : the variational multiscale method and interscale transfer operators.

    SciTech Connect

    Wagner, Gregory John; Collis, Samuel Scott; Templeton, Jeremy Alan; Lehoucq, Richard B.; Parks, Michael L.; Jones, Reese E.; Silling, Stewart Andrew; Scovazzi, Guglielmo; Bochev, Pavel B.

    2007-10-01

    This report is a collection of documents written as part of the Laboratory Directed Research and Development (LDRD) project A Mathematical Framework for Multiscale Science and Engineering: The Variational Multiscale Method and Interscale Transfer Operators. We present developments in two categories of multiscale mathematics and analysis. The first, continuum-to-continuum (CtC) multiscale, includes problems that allow application of the same continuum model at all scales with the primary barrier to simulation being computing resources. The second, atomistic-to-continuum (AtC) multiscale, represents applications where detailed physics at the atomistic or molecular level must be simulated to resolve the small scales, but the effect on and coupling to the continuum level is frequently unclear.

  2. Laser ultrasound technique applied in material characterization of thermally sprayed nickel aluminum coatings

    NASA Astrophysics Data System (ADS)

    Yeh, C. H.; Yang, C. H.; Hsiao, W. T.; Su, C.-Y.

    2012-05-01

    Thermal spraying processing usually uses a nickel-aluminum alloy system as the major powder due to its strong adhesion to substrates. The contents of powder material and the processing parameters used in the spraying process cause material properties of coatings exhibiting a wide variation. This research aims at nondestructive characterization of thermal spraying coatings. A laser-generation/laser-detection laser ultrasound technique (LUT) is used for the measurements of dispersion spectra of surface waves propagating along the coated surfaces. Theoretical model for surface waves propagating along a multi-layered structure with coating and substrate is used to model the sprayed coatings. An inversion algorithm based on Shuffled Complex Evolution (SCE-UA) is used to extract mechanical properties from the measured dispersion spectra cooperating with theoretical model. Three coatings with different sprayed powders and powder processing are investigated. Results indicate that substantial linear scatterings are observed for the inverted properties due to the measured dispersion spectra with limited bandwidth inherited from the relatively high attenuations. The slope of linear scattering can be used to distinguish the coating properties. The ANiBNb sample with ball-milled coating has the best properties based on its highest velocity and least attenuation. This method is potentially useful to characterize the mechanical properties of thermally spraying coating in a nondestructive way.

  3. Characterization of natural nanostructured hydroxyapatite obtained from the bones of Brazilian river fish

    NASA Astrophysics Data System (ADS)

    Coelho, T. M.; Nogueira, E. S.; Steimacher, A.; Medina, A. N.; Weinand, W. R.; Lima, W. M.; Baesso, M. L.; Bento, A. C.

    2006-11-01

    In this study, the characterization of the optical properties of natural hydroxyapatite (HAp) [Ca10(PO4)6(OH)2] is discussed. In the first stage of the experiment, natural HAp was processed from the bones of Brazilian river fish such as pintado (Pseudoplatystoma corruscans), jaú (Paulicea lutkeni), and cachara (Pseudoplatystoma fasciatum). The bones were calcined at 900°C for different amounts of time (4-12h) and reduced to powder using two different milling times (2 and 4h) in a high-energy ball mill, in order to determine the best procedure for obtaining natural nanostructured HAp powder for the study. In the second stage, material calcined for 8h was milled for 2, 4, 8, and 16h. The techniques of photoacoustic spectroscopy, scanning electron microscopy, and flame atomic absorption spectrometry were applied to characterize these samples. The O-H stretching shown by photoacoustic spectroscopy was correlated to the HAp nanostructure. Structural analysis indicated a Ca /P ratio close to 1.67 (˜1.64±0.04) and the presence of morphology and particle phase structure in the nanostructured HAp powder.

  4. Multi-element least square HDMR methods and their applications for stochastic multiscale model reduction

    SciTech Connect

    Jiang, Lijian Li, Xinping

    2015-08-01

    Stochastic multiscale modeling has become a necessary approach to quantify uncertainty and characterize multiscale phenomena for many practical problems such as flows in stochastic porous media. The numerical treatment of the stochastic multiscale models can be very challengeable as the existence of complex uncertainty and multiple physical scales in the models. To efficiently take care of the difficulty, we construct a computational reduced model. To this end, we propose a multi-element least square high-dimensional model representation (HDMR) method, through which the random domain is adaptively decomposed into a few subdomains, and a local least square HDMR is constructed in each subdomain. These local HDMRs are represented by a finite number of orthogonal basis functions defined in low-dimensional random spaces. The coefficients in the local HDMRs are determined using least square methods. We paste all the local HDMR approximations together to form a global HDMR approximation. To further reduce computational cost, we present a multi-element reduced least-square HDMR, which improves both efficiency and approximation accuracy in certain conditions. To effectively treat heterogeneity properties and multiscale features in the models, we integrate multiscale finite element methods with multi-element least-square HDMR for stochastic multiscale model reduction. This approach significantly reduces the original model's complexity in both the resolution of the physical space and the high-dimensional stochastic space. We analyze the proposed approach, and provide a set of numerical experiments to demonstrate the performance of the presented model reduction techniques. - Highlights: • Multi-element least square HDMR is proposed to treat stochastic models. • Random domain is adaptively decomposed into some subdomains to obtain adaptive multi-element HDMR. • Least-square reduced HDMR is proposed to enhance computation efficiency and approximation accuracy in certain

  5. Simulated shift work in rats perturbs multiscale regulation of locomotor activity.

    PubMed

    Hsieh, Wan-Hsin; Escobar, Carolina; Yugay, Tatiana; Lo, Men-Tzung; Pittman-Polletta, Benjamin; Salgado-Delgado, Roberto; Scheer, Frank A J L; Shea, Steven A; Buijs, Ruud M; Hu, Kun

    2014-07-01

    Motor activity possesses a multiscale regulation that is characterized by fractal activity fluctuations with similar structure across a wide range of timescales spanning minutes to hours. Fractal activity patterns are disturbed in animals after ablating the master circadian pacemaker (suprachiasmatic nucleus, SCN) and in humans with SCN dysfunction as occurs with aging and in dementia, suggesting the crucial role of the circadian system in the multiscale activity regulation. We hypothesized that the normal synchronization between behavioural cycles and the SCN-generated circadian rhythms is required for multiscale activity regulation. To test the hypothesis, we studied activity fluctuations of rats in a simulated shift work protocol that was designed to force animals to be active during the habitual resting phase of the circadian/daily cycle. We found that these animals had gradually decreased mean activity level and reduced 24-h activity rhythm amplitude, indicating disturbed circadian and behavioural cycles. Moreover, these animals had disrupted fractal activity patterns as characterized by more random activity fluctuations at multiple timescales from 4 to 12 h. Intriguingly, these activity disturbances exacerbated when the shift work schedule lasted longer and persisted even in the normal days (without forced activity) following the shift work. The disrupted circadian and fractal patterns resemble those of SCN-lesioned animals and of human patients with dementia, suggesting a detrimental impact of shift work on multiscale activity regulation. PMID:24829282

  6. Simulated shift work in rats perturbs multiscale regulation of locomotor activity

    PubMed Central

    Hsieh, Wan-Hsin; Escobar, Carolina; Yugay, Tatiana; Lo, Men-Tzung; Pittman-Polletta, Benjamin; Salgado-Delgado, Roberto; Scheer, Frank A. J. L.; Shea, Steven A.; Buijs, Ruud M.; Hu, Kun

    2014-01-01

    Motor activity possesses a multiscale regulation that is characterized by fractal activity fluctuations with similar structure across a wide range of timescales spanning minutes to hours. Fractal activity patterns are disturbed in animals after ablating the master circadian pacemaker (suprachiasmatic nucleus, SCN) and in humans with SCN dysfunction as occurs with aging and in dementia, suggesting the crucial role of the circadian system in the multiscale activity regulation. We hypothesized that the normal synchronization between behavioural cycles and the SCN-generated circadian rhythms is required for multiscale activity regulation. To test the hypothesis, we studied activity fluctuations of rats in a simulated shift work protocol that was designed to force animals to be active during the habitual resting phase of the circadian/daily cycle. We found that these animals had gradually decreased mean activity level and reduced 24-h activity rhythm amplitude, indicating disturbed circadian and behavioural cycles. Moreover, these animals had disrupted fractal activity patterns as characterized by more random activity fluctuations at multiple timescales from 4 to 12 h. Intriguingly, these activity disturbances exacerbated when the shift work schedule lasted longer and persisted even in the normal days (without forced activity) following the shift work. The disrupted circadian and fractal patterns resemble those of SCN-lesioned animals and of human patients with dementia, suggesting a detrimental impact of shift work on multiscale activity regulation. PMID:24829282

  7. Local variance for multi-scale analysis in geomorphometry

    PubMed Central

    Drăguţ, Lucian; Eisank, Clemens; Strasser, Thomas

    2011-01-01

    Increasing availability of high resolution Digital Elevation Models (DEMs) is leading to a paradigm shift regarding scale issues in geomorphometry, prompting new solutions to cope with multi-scale analysis and detection of characteristic scales. We tested the suitability of the local variance (LV) method, originally developed for image analysis, for multi-scale analysis in geomorphometry. The method consists of: 1) up-scaling land-surface parameters derived from a DEM; 2) calculating LV as the average standard deviation (SD) within a 3 × 3 moving window for each scale level; 3) calculating the rate of change of LV (ROC-LV) from one level to another, and 4) plotting values so obtained against scale levels. We interpreted peaks in the ROC-LV graphs as markers of scale levels where cells or segments match types of pattern elements characterized by (relatively) equal degrees of homogeneity. The proposed method has been applied to LiDAR DEMs in two test areas different in terms of roughness: low relief and mountainous, respectively. For each test area, scale levels for slope gradient, plan, and profile curvatures were produced at constant increments with either resampling (cell-based) or image segmentation (object-based). Visual assessment revealed homogeneous areas that convincingly associate into patterns of land-surface parameters well differentiated across scales. We found that the LV method performed better on scale levels generated through segmentation as compared to up-scaling through resampling. The results indicate that coupling multi-scale pattern analysis with delineation of morphometric primitives is possible. This approach could be further used for developing hierarchical classifications of landform elements. PMID:21779138

  8. Multiscale geometric modeling of macromolecules I: Cartesian representation

    NASA Astrophysics Data System (ADS)

    Xia, Kelin; Feng, Xin; Chen, Zhan; Tong, Yiying; Wei, Guo-Wei

    2014-01-01

    This paper focuses on the geometric modeling and computational algorithm development of biomolecular structures from two data sources: Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB) in the Eulerian (or Cartesian) representation. Molecular surface (MS) contains non-smooth geometric singularities, such as cusps, tips and self-intersecting facets, which often lead to computational instabilities in molecular simulations, and violate the physical principle of surface free energy minimization. Variational multiscale surface definitions are proposed based on geometric flows and solvation analysis of biomolecular systems. Our approach leads to geometric and potential driven Laplace-Beltrami flows for biomolecular surface evolution and formation. The resulting surfaces are free of geometric singularities and minimize the total free energy of the biomolecular system. High order partial differential equation (PDE)-based nonlinear filters are employed for EMDB data processing. We show the efficacy of this approach in feature-preserving noise reduction. After the construction of protein multiresolution surfaces, we explore the analysis and characterization of surface morphology by using a variety of curvature definitions. Apart from the classical Gaussian curvature and mean curvature, maximum curvature, minimum curvature, shape index, and curvedness are also applied to macromolecular surface analysis for the first time. Our curvature analysis is uniquely coupled to the analysis of electrostatic surface potential, which is a by-product of our variational multiscale solvation models. As an expository investigation, we particularly emphasize the numerical algorithms and computational protocols for practical applications of the above multiscale geometric models. Such information may otherwise be scattered over the vast literature on this topic. Based on the curvature and electrostatic analysis from our multiresolution surfaces, we introduce a new concept, the

  9. Multiscale geometric modeling of macromolecules I: Cartesian representation

    SciTech Connect

    Xia, Kelin; Feng, Xin; Chen, Zhan; Tong, Yiying; Wei, Guo-Wei

    2014-01-15

    This paper focuses on the geometric modeling and computational algorithm development of biomolecular structures from two data sources: Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB) in the Eulerian (or Cartesian) representation. Molecular surface (MS) contains non-smooth geometric singularities, such as cusps, tips and self-intersecting facets, which often lead to computational instabilities in molecular simulations, and violate the physical principle of surface free energy minimization. Variational multiscale surface definitions are proposed based on geometric flows and solvation analysis of biomolecular systems. Our approach leads to geometric and potential driven Laplace–Beltrami flows for biomolecular surface evolution and formation. The resulting surfaces are free of geometric singularities and minimize the total free energy of the biomolecular system. High order partial differential equation (PDE)-based nonlinear filters are employed for EMDB data processing. We show the efficacy of this approach in feature-preserving noise reduction. After the construction of protein multiresolution surfaces, we explore the analysis and characterization of surface morphology by using a variety of curvature definitions. Apart from the classical Gaussian curvature and mean curvature, maximum curvature, minimum curvature, shape index, and curvedness are also applied to macromolecular surface analysis for the first time. Our curvature analysis is uniquely coupled to the analysis of electrostatic surface potential, which is a by-product of our variational multiscale solvation models. As an expository investigation, we particularly emphasize the numerical algorithms and computational protocols for practical applications of the above multiscale geometric models. Such information may otherwise be scattered over the vast literature on this topic. Based on the curvature and electrostatic analysis from our multiresolution surfaces, we introduce a new concept, the

  10. Multiscale geometric modeling of macromolecules I: Cartesian representation

    PubMed Central

    Xia, Kelin; Feng, Xin; Chen, Zhan; Tong, Yiying; Wei, Guo Wei

    2013-01-01

    This paper focuses on the geometric modeling and computational algorithm development of biomolecular structures from two data sources: Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB) in the Eulerian (or Cartesian) representation. Molecular surface (MS) contains non-smooth geometric singularities, such as cusps, tips and self-intersecting facets, which often lead to computational instabilities in molecular simulations, and violate the physical principle of surface free energy minimization. Variational multiscale surface definitions are proposed based on geometric flows and solvation analysis of biomolecular systems. Our approach leads to geometric and potential driven Laplace-Beltrami flows for biomolecular surface evolution and formation. The resulting surfaces are free of geometric singularities and minimize the total free energy of the biomolecular system. High order partial differential equation (PDE)-based nonlinear filters are employed for EMDB data processing. We show the efficacy of this approach in feature-preserving noise reduction. After the construction of protein multiresolution surfaces, we explore the analysis and characterization of surface morphology by using a variety of curvature definitions. Apart from the classical Gaussian curvature and mean curvature, maximum curvature, minimum curvature, shape index, and curvedness are also applied to macromolecular surface analysis for the first time. Our curvature analysis is uniquely coupled to the analysis of electrostatic surface potential, which is a by-product of our variational multiscale solvation models. As an expository investigation, we particularly emphasize the numerical algorithms and computational protocols for practical applications of the above multiscale geometric models. Such information may otherwise be scattered over the vast literature on this topic. Based on the curvature and electrostatic analysis from our multiresolution surfaces, we introduce a new concept, the

  11. Multiscale geometric modeling of macromolecules I: Cartesian representation.

    PubMed

    Xia, Kelin; Feng, Xin; Chen, Zhan; Tong, Yiying; Wei, Guo Wei

    2014-01-01

    This paper focuses on the geometric modeling and computational algorithm development of biomolecular structures from two data sources: Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB) in the Eulerian (or Cartesian) representation. Molecular surface (MS) contains non-smooth geometric singularities, such as cusps, tips and self-intersecting facets, which often lead to computational instabilities in molecular simulations, and violate the physical principle of surface free energy minimization. Variational multiscale surface definitions are proposed based on geometric flows and solvation analysis of biomolecular systems. Our approach leads to geometric and potential driven Laplace-Beltrami flows for biomolecular surface evolution and formation. The resulting surfaces are free of geometric singularities and minimize the total free energy of the biomolecular system. High order partial differential equation (PDE)-based nonlinear filters are employed for EMDB data processing. We show the efficacy of this approach in feature-preserving noise reduction. After the construction of protein multiresolution surfaces, we explore the analysis and characterization of surface morphology by using a variety of curvature definitions. Apart from the classical Gaussian curvature and mean curvature, maximum curvature, minimum curvature, shape index, and curvedness are also applied to macromolecular surface analysis for the first time. Our curvature analysis is uniquely coupled to the analysis of electrostatic surface potential, which is a by-product of our variational multiscale solvation models. As an expository investigation, we particularly emphasize the numerical algorithms and computational protocols for practical applications of the above multiscale geometric models. Such information may otherwise be scattered over the vast literature on this topic. Based on the curvature and electrostatic analysis from our multiresolution surfaces, we introduce a new concept, the

  12. The wavelet response as a multiscale NDT method.

    PubMed

    Le Gonidec, Y; Conil, F; Gibert, D

    2003-08-01

    We analyze interfaces by using reflected waves in the framework of the wavelet transform. First, we introduce the wavelet transform as an efficient method to detect and characterize a discontinuity in the acoustical impedance profile of a material. Synthetic examples are shown for both an isolated reflector and multiscale clusters of nearby defects. In the second part of the paper we present the wavelet response method as a natural extension of the wavelet transform when the velocity profile to be analyzed can only be remotely probed by propagating wavelets through the medium (instead of being directly convolved as in the wavelet transform). The wavelet response is constituted by the reflections of the incident wavelets on the discontinuities and we show that both transforms are equivalent when multiple scattering is neglected. We end this paper by experimentally applying the wavelet response in an acoustic tank to characterize planar reflectors with finite thicknesses. PMID:12853084

  13. Multiscale Modeling of Hematologic Disorders

    SciTech Connect

    Fedosov, Dmitry A.; Pivkin, Igor; Pan, Wenxiao; Dao, Ming; Caswell, Bruce; Karniadakis, George E.

    2012-01-28

    Parasitic infectious diseases and other hereditary hematologic disorders are often associated with major changes in the shape and viscoelastic properties of red blood cells (RBCs). Such changes can disrupt blood flow and even brain perfusion, as in the case of cerebral malaria. Modeling of these hematologic disorders requires a seamless multiscale approach, where blood cells and blood flow in the entire arterial tree are represented accurately using physiologically consistent parameters. In this chapter, we present a computational methodology based on dissipative particle dynamics (DPD) which models RBCs as well as whole blood in health and disease. DPD is a Lagrangian method that can be derived from systematic coarse-graining of molecular dynamics but can scale efficiently up to small arteries and can also be used to model RBCs down to spectrin level. To this end, we present two complementary mathematical models for RBCs and describe a systematic procedure on extracting the relevant input parameters from optical tweezers and microfluidic experiments for single RBCs. We then use these validated RBC models to predict the behavior of whole healthy blood and compare with experimental results. The same procedure is applied to modeling malaria, and results for infected single RBCs and whole blood are presented.

  14. A Multiscale Bidirectional Coupling Framework

    SciTech Connect

    Kabilan, Senthil; Kuprat, Andrew P.; Hlastala, Michael P.; Corley, Richard A.; Einstein, Daniel R.

    2011-12-01

    The lung is geometrically articulated across multiple scales from the trachea to the alveoli. A major computational challenge is to tightly link ODEs that describe lower scales to 3D finite element or finite volume models of airway mechanics using iterative communication between scales. In this study, we developed a novel multiscale computational framework for bidirectionally coupling 3D CFD models and systems of lower order ODEs. To validate the coupling framework, a four and eight generation Weibel lung model was constructed. For the coupled CFD-ODE simulations, the lung models were truncated at different generations and a RL circuit represented the truncated portion. The flow characteristics from the coupled models were compared to untruncated full 3D CFD models at peak inhalation and peak exhalation. Results showed that at no time or simulation was the difference in mass flux and/or pressure at a given location between uncoupled and coupled models was greater than 2.43%. The flow characteristics at prime locations for the coupled models showed good agreement to uncoupled models. Remarkably, due to reuse of the Krylov subspace, the cost of the ODE coupling is not much greater than uncoupled full 3D-CFD computations with simple prescribed pressure values at the outlets.

  15. MULTISCALE DISCRETIZATION OF SHAPE CONTOURS

    SciTech Connect

    Prasad, L.; Rao, R.

    2000-09-01

    We present an efficient multi-scale scheme to adaptively approximate the continuous (or densely sampled) contour of a planar shape at varying resolutions. The notion of shape is intimately related to the notion of contour, and the efficient representation of the contour of a shape is vital to a computational understanding of the shape. Any polygonal approximation of a planar smooth curve is equivalent to a piecewise constant approximation of the parameterized X and Y coordinate functions of a discrete point set obtained by densely sampling the curve. Using the Haar wavelet transform for the piecewise approximation yields a hierarchical scheme in which the size of the approximating point set is traded off against the morphological accuracy of the approximation. Our algorithm compresses the representation of the initial shape contour to a sparse sequence of points in the plane defining the vertices of the shape's polygonal approximation. Furthermore, it is possible to control the overall resolution of the approximation by a single, scale-independent parameter.

  16. Multiscale structure of sheet nacre.

    PubMed

    Rousseau, Marthe; Lopez, Evelyne; Stempflé, Philippe; Brendlé, Marcel; Franke, Loïc; Guette, Alain; Naslain, Roger; Bourrat, Xavier

    2005-11-01

    This work was conducted on Pinctada maxima nacre (mother of pearl) in order to understand its multiscale ordering and the role of the organic matrix in its structure. Intermittent-contact atomic force microscopy with phase detection imaging reveals a nanostructure within the tablet. A continuous organic framework divides each tablet into nanograins. Their shape is supposed to be flat with a mean extension of 45nm. TEM performed in the darkfield mode evidences that at least part of the intracrystalline matrix is crystallized and responds like a 'single crystal'. The tablet is a 'hybrid composite'. The organic matrix is continuous. The mineral phase is thus finely divided still behaving as a single crystal. It is proposed that each tablet results from the coherent aggregation of nanograins keeping strictly the same crystallographic orientation thanks to a hetero-epitaxy mechanism. Finally, high-resolution TEM performed on bridges from one tablet to the next, in the overlying row, did not permit to evidence a mineral lattice but crystallized organic bridges. The same organic bridges were evidenced by SEM in the interlaminar sequence. PMID:15907339

  17. Multiscale modelling of evolving foams

    NASA Astrophysics Data System (ADS)

    Saye, R. I.; Sethian, J. A.

    2016-06-01

    We present a set of multi-scale interlinked algorithms to model the dynamics of evolving foams. These algorithms couple the key effects of macroscopic bubble rearrangement, thin film drainage, and membrane rupture. For each of the mechanisms, we construct consistent and accurate algorithms, and couple them together to work across the wide range of space and time scales that occur in foam dynamics. These algorithms include second order finite difference projection methods for computing incompressible fluid flow on the macroscale, second order finite element methods to solve thin film drainage equations in the lamellae and Plateau borders, multiphase Voronoi Implicit Interface Methods to track interconnected membrane boundaries and capture topological changes, and Lagrangian particle methods for conservative liquid redistribution during rearrangement and rupture. We derive a full set of numerical approximations that are coupled via interface jump conditions and flux boundary conditions, and show convergence for the individual mechanisms. We demonstrate our approach by computing a variety of foam dynamics, including coupled evolution of three-dimensional bubble clusters attached to an anchored membrane and collapse of a foam cluster.

  18. Multiscale simulation of erythrocyte membranes

    NASA Astrophysics Data System (ADS)

    Peng, Zhangli; Asaro, Robert J.; Zhu, Qiang

    2010-03-01

    To quantitatively predict the mechanical response and mechanically induced remodeling of red blood cells, we developed a multiscale method to correlate distributions of internal stress with overall cell deformation. This method consists of three models at different length scales: in the complete cell level the membrane is modeled as two distinct layers of continuum shells using finite element method (Level III), in which the skeleton-bilayer interactions are depicted as a slide in the lateral (i.e., in-plane) direction (caused by the mobility of the skeleton-bilayer pinning points) and a normal contact force; the constitutive laws of the inner layer (the protein skeleton) are obtained from a molecular-based model (Level II); the mechanical properties of the spectrin (Sp, a key component of the skeleton), including its folding/unfolding reactions, are obtained with a stress-strain model (Level I). Model verification is achieved through comparisons with existing numerical and experimental studies in terms of the resting shape of the cell as well as cell deformations induced by micropipettes and optical tweezers. Detailed distributions of the interaction force between the lipid bilayer and the skeleton that may cause their dissociation and lead to phenomena such as vesiculation are predicted. Specifically, our model predicts correlation between the occurrence of Sp unfolding and increase in the mechanical load upon individual skeleton-bilayer pinning points. Finally a simulation of the necking process after skeleton-bilayer dissociation, a precursor of vesiculation, is conducted.

  19. Stochastic multiscale modeling of polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Wen, Bin

    Mechanical properties of engineering materials are sensitive to the underlying random microstructure. Quantification of mechanical property variability induced by microstructure variation is essential for the prediction of extreme properties and microstructure-sensitive design of materials. Recent advances in high throughput characterization of polycrystalline microstructures have resulted in huge data sets of microstructural descriptors and image snapshots. To utilize these large scale experimental data for computing the resulting variability of macroscopic properties, appropriate mathematical representation of microstructures is needed. By exploring the space containing all admissible microstructures that are statistically similar to the available data, one can estimate the distribution/envelope of possible properties by employing efficient stochastic simulation methodologies along with robust physics-based deterministic simulators. The focus of this thesis is on the construction of low-dimensional representations of random microstructures and the development of efficient physics-based simulators for polycrystalline materials. By adopting appropriate stochastic methods, such as Monte Carlo and Adaptive Sparse Grid Collocation methods, the variability of microstructure-sensitive properties of polycrystalline materials is investigated. The primary outcomes of this thesis include: (1) Development of data-driven reduced-order representations of microstructure variations to construct the admissible space of random polycrystalline microstructures. (2) Development of accurate and efficient physics-based simulators for the estimation of material properties based on mesoscale microstructures. (3) Investigating property variability of polycrystalline materials using efficient stochastic simulation methods in combination with the above two developments. The uncertainty quantification framework developed in this work integrates information science and materials science, and

  20. Prediction of hydraulic and electrical transport properties of sandstone with multiscale lattice Boltzmann/finite element simulation on microtomographic images

    NASA Astrophysics Data System (ADS)

    Wong, T.; Sun, W.

    2012-12-01

    Microcomputed tomography can be used to characterize the geometry of the pore space of a sedimentary rock, with resolution that is sufficiently refined for the realistic simulation of physical properties based on the 3D image. Significant advances have been made on the characterization of pore size distribution and connectivity, development of techniques such as lattice Boltzmann method to simulate permeability, and its upscaling. Sun, Andrade and Rudnicki (2011) recently introduced a multiscale method that dynamically links these three aspects, which were often treated separately in previous computational schemes. In this study, we improve the efficiency of this multiscale method by introducing a flood-fill algorithm to determine connectivity of the pores, followed by a multiscale lattice Boltzmann/finite element calculation to obtain homogenized effective anisotropic permeability. The improved multiscale method also includes new capacity to consistently determine electrical conductivity and formation factor from CT images. Furthermore, we also introduce a level set based method that transforms pore geometry to finite element mesh and thus enables direct simulation of pore-scale flow with finite element method. When applied to the microCT data acquired by Lindquist et al. (2000) for four Fontainebleau sandstone samples with porosities ranging from 7.5% to 22%, this multiscale method has proved to be computationally efficient and our simulations has provided new insights into the relation among permeability, pore geometry and connectivity.

  1. A Hybrid Multiscale Framework for Subsurface Flow and Transport Simulations

    SciTech Connect

    Scheibe, Timothy D.; Yang, Xiaofan; Chen, Xingyuan; Hammond, Glenn E.

    2015-06-01

    Extensive research efforts have been invested in reducing model errors to improve the predictive ability of biogeochemical earth and environmental system simulators, with applications ranging from contaminant transport and remediation to impacts of biogeochemical elemental cycling (e.g., carbon and nitrogen) on local ecosystems and regional to global climate. While the bulk of this research has focused on improving model parameterizations in the face of observational limitations, the more challenging type of model error/uncertainty to identify and quantify is model structural error which arises from incorrect mathematical representations of (or failure to consider) important physical, chemical, or biological processes, properties, or system states in model formulations. While improved process understanding can be achieved through scientific study, such understanding is usually developed at small scales. Process-based numerical models are typically designed for a particular characteristic length and time scale. For application-relevant scales, it is generally necessary to introduce approximations and empirical parameterizations to describe complex systems or processes. This single-scale approach has been the best available to date because of limited understanding of process coupling combined with practical limitations on system characterization and computation. While computational power is increasing significantly and our understanding of biological and environmental processes at fundamental scales is accelerating, using this information to advance our knowledge of the larger system behavior requires the development of multiscale simulators. Accordingly there has been much recent interest in novel multiscale methods in which microscale and macroscale models are explicitly coupled in a single hybrid multiscale simulation. A limited number of hybrid multiscale simulations have been developed for biogeochemical earth systems, but they mostly utilize application

  2. A Hybrid Multiscale Framework for Subsurface Flow and Transport Simulations

    DOE PAGESBeta

    Scheibe, Timothy D.; Yang, Xiaofan; Chen, Xingyuan; Hammond, Glenn E.

    2015-06-01

    Extensive research efforts have been invested in reducing model errors to improve the predictive ability of biogeochemical earth and environmental system simulators, with applications ranging from contaminant transport and remediation to impacts of biogeochemical elemental cycling (e.g., carbon and nitrogen) on local ecosystems and regional to global climate. While the bulk of this research has focused on improving model parameterizations in the face of observational limitations, the more challenging type of model error/uncertainty to identify and quantify is model structural error which arises from incorrect mathematical representations of (or failure to consider) important physical, chemical, or biological processes, properties, ormore » system states in model formulations. While improved process understanding can be achieved through scientific study, such understanding is usually developed at small scales. Process-based numerical models are typically designed for a particular characteristic length and time scale. For application-relevant scales, it is generally necessary to introduce approximations and empirical parameterizations to describe complex systems or processes. This single-scale approach has been the best available to date because of limited understanding of process coupling combined with practical limitations on system characterization and computation. While computational power is increasing significantly and our understanding of biological and environmental processes at fundamental scales is accelerating, using this information to advance our knowledge of the larger system behavior requires the development of multiscale simulators. Accordingly there has been much recent interest in novel multiscale methods in which microscale and macroscale models are explicitly coupled in a single hybrid multiscale simulation. A limited number of hybrid multiscale simulations have been developed for biogeochemical earth systems, but they mostly utilize application

  3. Multiscale Modeling of Plastic Bonded Explosives

    NASA Astrophysics Data System (ADS)

    Smith, Grant; Bedrov, Dmitry; Borodin, Oleg

    2007-06-01

    We have developed a multiscale modeling paradigm for the prediction of the viscoelastic properties, equation of state and yielding behavior of plastic bonded explosives (PBXs). In our multiscale modeling approach the components of the explosive (e.g., energetic material, metal and binder) are explicitly resolved and the material point method (MPM) is utilized to predict the response of the composite material to loading (isentropic, shock, etc.). This data are then utilized to develop equation-of-state and constitutive models for the PBX. The properties of the components are determined either from atomistic simulations or are taken from the literature. Force fields for the atomistic simulations in turn have been developed based upon high-level electronic structure calculations of model compounds and molecular complexes. Hence, our multiscale simulation approach systematically bridges length scales from atomistic to macroscopic. Applications of this approach to PBX-9501 and other PBXs will be considered.

  4. Multiscale Computational Models of Complex Biological Systems

    PubMed Central

    Walpole, Joseph; Papin, Jason A.; Peirce, Shayn M.

    2014-01-01

    Integration of data across spatial, temporal, and functional scales is a primary focus of biomedical engineering efforts. The advent of powerful computing platforms, coupled with quantitative data from high-throughput experimental platforms, has allowed multiscale modeling to expand as a means to more comprehensively investigate biological phenomena in experimentally relevant ways. This review aims to highlight recently published multiscale models of biological systems while using their successes to propose the best practices for future model development. We demonstrate that coupling continuous and discrete systems best captures biological information across spatial scales by selecting modeling techniques that are suited to the task. Further, we suggest how to best leverage these multiscale models to gain insight into biological systems using quantitative, biomedical engineering methods to analyze data in non-intuitive ways. These topics are discussed with a focus on the future of the field, the current challenges encountered, and opportunities yet to be realized. PMID:23642247

  5. Multiscale stochastic approach for phase screens synthesis.

    PubMed

    Beghi, Alessandro; Cenedese, Angelo; Masiero, Andrea

    2011-07-20

    Simulating the turbulence effect on ground telescope observations is of fundamental importance for the design and test of suitable control algorithms for adaptive optics systems. In this paper we propose a multiscale approach for efficiently synthesizing turbulent phases at very high resolution. First, the turbulence is simulated at low resolution, taking advantage of a previously developed method for generating phase screens [J. Opt. Soc. Am. A 25, 515 (2008)]. Then, high-resolution phase screens are obtained as the output of a multiscale linear stochastic system. The multiscale approach significantly improves the computational efficiency of turbulence simulation with respect to recently developed methods [Opt. Express 14, 988 (2006)] [J. Opt. Soc. Am. A 25, 515 (2008)] [J. Opt. Soc. Am. A 25, 463 (2008)]. Furthermore, the proposed procedure ensures good accuracy in reproducing the statistical characteristics of the turbulent phase. PMID:21772400

  6. The Center for Multiscale Plasma Dynamics

    SciTech Connect

    Kevrekidis, Yannis G

    2015-01-20

    This final report describes research performed in Princeton University, led by Professor Yannis G. Kevrekidis, over a period of six years (August 1, 2014 to July 31, 2010, including a one-year, no-cost extension) as part of the Center for Multiscale Plasma Dynamics led by the University of Maryland. The work resulted in the development and implementation of several multiscale algorithms based on the equation-free approach pioneered by the PI, including its applications in plasma dynamics problems. These algoriithms include coarse projective integration and coarse stability/bifurcation computations. In the later stages of the work, new links were made between this multiscale, coarse-graining approach and advances in data mining/machine learning algorithms.

  7. A multiscale modeling approach to adhesive contact

    NASA Astrophysics Data System (ADS)

    Fan, KangQi; Wang, WeiDong; Zhu, YingMin; Zhang, XiuYan

    2011-09-01

    In order to model the adhesive contact across different length scales, a multiscale approach is developed and used to study the adhesive contact behaviors between a rigid cylinder and an elastic face-centered cubic (FCC) substrate. The approach combines an atomistic treatment of the interfacial region with an elastic mechanics method description of the continuum region. The two regions are connected by a coupling region where nodes of the continuum region are refined to atoms of the atomistic region. Moreover, the elastic constants of FCC crystals are obtained directly from the Lennard-Jones potential to describe the elastic response characteristics of the continuum region, which ensures the consistency of material proprieties between atomistic and continuum regions. The multiscale approach is examined by comparing it with the pure MD simulation, and the results indicate that the multiscale modeling approach agrees well with the MD method in studying the adhesive contact behaviors.

  8. Preparation and characterization of physically modified glass beads used as model carriers in dry powder inhalers.

    PubMed

    Zellnitz, Sarah; Redlinger-Pohn, Jakob Dominik; Kappl, Michael; Schroettner, Hartmuth; Urbanetz, Nora Anne

    2013-04-15

    The aim of this work is the physical modification and characterization of the surface topography of glass beads used as model carriers in dry powder inhalers (DPIs). By surface modification the contact area between drug and carrier and thereby interparticle forces may be modified. Thus the performance of DPIs that relies on interparticle interactions may be improved. Glass beads were chosen as model carriers because various prospects of physical surface modification may be applied without affecting other factors also impacting interparticle interactions like particle size and shape. To generate rough surfaces glass beads were processed mechanically by friction and impaction in a ball mill with different grinding materials that were smaller and harder with respect to the glass beads. By varying the grinding time (4 h, 8 h) and by using different grinding media (tungsten carbide, quartz) surfaces with different shades of roughness were generated. Depending on the hardness of the grinding material and the grinding time the surface roughness was more or less pronounced. Surface roughness parameters and specific surface area were determined via several complementary techniques in order to get an enhanced understanding of the impact of the modifying procedure on the surface properties of the glass beads. PMID:23470233

  9. Synthesis and Characterization of Al-Doped Mg2Si Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Battiston, S.; Fiameni, S.; Saleemi, M.; Boldrini, S.; Famengo, A.; Agresti, F.; Stingaciu, M.; Toprak, M. S.; Fabrizio, M.; Barison, S.

    2013-07-01

    Magnesium silicide (Mg2Si)-based alloys are promising candidates for thermoelectric (TE) energy conversion for the middle to high range of temperature. These materials are very attractive for TE research because of the abundance of their constituent elements in the Earth's crust. Mg2Si could replace lead-based TE materials, due to its low cost, nontoxicity, and low density. In this work, the role of aluminum doping (Mg2Si:Al = 1: x for x = 0.005, 0.01, 0.02, and 0.04 molar ratio) in dense Mg2Si materials was investigated. The synthesis process was performed by planetary milling under inert atmosphere starting from commercial Mg2Si pieces and Al powder. After ball milling, the samples were sintered by means of spark plasma sintering to density >95%. The morphology, composition, and crystal structure of the samples were characterized by field-emission scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction analyses. Moreover, Seebeck coefficient analyses, as well as electrical and thermal conductivity measurements were performed for all samples up to 600°C. The resultant estimated ZT values are comparable to those reported in the literature for these materials. In particular, the maximum ZT achieved was 0.50 for the x = 0.01 Al-doped sample at 600°C.

  10. Preparation and Characterization of Bi2Te3/Graphite/Polythiophene Thermoelectric Composites

    NASA Astrophysics Data System (ADS)

    Lai, Chunhua; Li, Junjie; Pan, Chengjun; Wang, Lei; Bai, Xiaojun

    2016-06-01

    The Bi2Te3/graphite/polythiophene composites were prepared by solution mixing, mechanical ball milling, cold pressing and spark plasma sintering (SPS) in order to utilize and integrate the high Seebeck coefficient of Bi2Te3, high electrical conductivity of graphite (G) and low thermal conductivity of polythiophene (PTh). The structures and properties of the composites were characterized by scanning electron microscope, thermo gravimetric analyzer, x-ray diffraction and ULVAC ZEM-2 Seebeck coefficient measurement. The results showed that the related components were uniformly dispersed in the composites, and the electrical conductivity of the composites increased significantly with increasing G content. A small addition of Bi2Te3 to the matrix contributed to an increase in Seebeck coefficient and the thermal conductivity of the composites stayed at a low level owing to the low thermal conductivity of PTh. These composites prepared by SPS show an increase in Seebeck coefficient but a decrease in electrical conductivity as compared to corresponding composites prepared by cold pressing.

  11. Fabrication and characterization of hexagonal boron nitride powder by spray drying and calcining nitriding technology

    NASA Astrophysics Data System (ADS)

    Shi, Xiaoliang; Wang, Sheng; Yang, Hua; Duan, Xinglong; Dong, Xuebin

    2008-09-01

    Hexagonal boron nitride (hBN) powder was fabricated prepared by the spray drying and calcining-nitriding technology. The effects of nitrided temperature on the phases, morphology and particle size distribution of hBN powder, were investigated. The synthesized powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transformed infrared spectrum, ultraviolet-visible (UV-vis) spectrum and photoluminescence (PL) spectrum. UV-vis spectrum revealed that the product had one obvious band gap (4.7 eV) and PL spectrum showed that it had a visible emission at 457 nm ( λex=230 nm). FESEM image indicated that the particle size of the synthesized hBN was mainly in the range of 0.5-1.5 μm in diameter, and 50-150 nm in thickness. The high-energy ball-milling process following 900 °C calcining process was very helpful to obtain fully crystallized hBN at lower temperature.

  12. Investigation of Al2O3-MWCNTs hybrid dispersion in water and their thermal characterization.

    PubMed

    Nine, M J; Batmunkh, Munkhbayar; Kim, Jun-Hyo; Chung, Han-Shik; Jeong, Hyo-Min

    2012-06-01

    Synthesis of water based Al2O3-MWCNTs hybrid nanofluids have been investigated and characterized. Al2O3-MWCNTs nanoparticles in weight proportion of 97.5:2.5 to 90:10 have been studied over 1% to 6% weight concentration. Dispersion quality of nanofluids is assured by additional synthesis process like acids treatment and grinding of MWCNTs by planetary ball mill. The effects of ground and non-ground MWCNTs over dispersion quality and thermal conductivity have been investigated. Sedimentation effect of hybrid nanofluids with time length has been studied by sample visualization and TEM micrographs. The augmentative absorbance and thermal conductivity of hybrid nanofluids have been compared with pure Al2O3/water nanofluids. The overall result shows that the enhancement in normalized thermal conductivity of hybrid nanofluids is still not so sharp though the absorbance and other qualities show much better comparing mono type nanofluids. Hybrid nanofluids with spherical particles show a smaller increase in thermal conductivity comparing cylindrical shape particles. PMID:22905499

  13. Formulation and characterization of a plasma sterilized, pharmaceutical grade chitosan powder.

    PubMed

    Crofton, Andrew R; Hudson, Samuel M; Howard, Kristy; Pender, Tyler; Abdelgawad, Abdelrahman; Wolski, Daniel; Kirsch, Wolff M

    2016-08-01

    Chitosan has great potential as a pharmaceutical excipient. In this study, chitosan flake was micronized using cryo-ball and cryo-jet milling and subsequently sterilized with nitrogen plasma. Micronized chitosan was characterized by laser diffraction, scanning electron microscopy (SEM), conductometric titration, viscometry, loss on drying, FTIR, and limulus amebocyte lysate (LAL) assays. Cryo-jet milling produced mean particle size of 16.05μm, 44% smaller than cryo-ball milling. Cryomilled chitosan demonstrated increased hygroscopicity, but reduced molecular weight and degree of deacetylation (DD). SEM imaging showed highly irregular shapes. FTIR showed changes consistent with reduced DD and an unexplained shift at 1100cm(-1). Plasma treated chitosan was sterile with <2.5EU/g after low-pressure plasma and <1.3EU/g after atmospheric pressure plasma treatment. Plasma treatment decreased the reduced viscosity of chitosan flake and powder, with a greater effect on powder. In conclusion, pharmaceutical grade, sterile chitosan powder was produced with cryo-jet milling and plasma sterilization. PMID:27112892

  14. Dynamics of a neural system with a multiscale architecture

    PubMed Central

    Breakspear, Michael; Stam, Cornelis J

    2005-01-01

    The architecture of the brain is characterized by a modular organization repeated across a hierarchy of spatial scales—neurons, minicolumns, cortical columns, functional brain regions, and so on. It is important to consider that the processes governing neural dynamics at any given scale are not only determined by the behaviour of other neural structures at that scale, but also by the emergent behaviour of smaller scales, and the constraining influence of activity at larger scales. In this paper, we introduce a theoretical framework for neural systems in which the dynamics are nested within a multiscale architecture. In essence, the dynamics at each scale are determined by a coupled ensemble of nonlinear oscillators, which embody the principle scale-specific neurobiological processes. The dynamics at larger scales are ‘slaved’ to the emergent behaviour of smaller scales through a coupling function that depends on a multiscale wavelet decomposition. The approach is first explicated mathematically. Numerical examples are then given to illustrate phenomena such as between-scale bifurcations, and how synchronization in small-scale structures influences the dynamics in larger structures in an intuitive manner that cannot be captured by existing modelling approaches. A framework for relating the dynamical behaviour of the system to measured observables is presented and further extensions to capture wave phenomena and mode coupling are suggested. PMID:16087448

  15. Liquid crystal lens focusing in monocentric multiscale imagers

    NASA Astrophysics Data System (ADS)

    Stamenov, Igor; Tremblay, Eric; Baker, Katherine A.; McLaughlin, Paul; Ford, Joseph E.

    2012-10-01

    In multiscale imagers a single objective lens is shared by multiple secondary optical systems, so that a high-resolution wide-angle image is acquired in overlapping fields sensed by multiple conventional focal planes. In the "AWARE2" 2 Gigapixel imager, F/2.4 optics cover a 120 degree field of view using a monocentric glass primary lens shared by 221 molded plastic subimagers, each with a 14 Megapixel focal plane. Such imagers can independently focus parts of the image field, allowing wide-angle imaging over relatively close and deep image fields. However, providing hundreds of independent mechanical focus adjustments has a significant system impact in terms of complexity, bulk, and cost. In this paper we explore the use of an electronically controlled liquid crystal lens for focus of multiscale imagers in general, and demonstrate use with the AWARE2 imager optics. The Lens Vector Auto Focus (LVAF) liquid crystal lens provides up to 5 diopters of optical power over a 2.2mm aperture diameter, the maximum currently available aperture. However, a custom lens using the same materials and basic structure can provide the 5 diopters power and 6.4 mm aperture required to obtain full resolution overlapping image fields in the AWARE2 imager. We characterize the LVAF lens and the optical performance of the LVAF lens in the current AWARE2 prototype, comparing the measured and optically modeled resolution, and demonstrating software control of focus from infinity to an 2m object distance.

  16. Multiscale Modeling of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Mital, Subodh K.; Pineda, Evan J.; Arnold, Steven M.

    2015-01-01

    Results of multiscale modeling simulations of the nonlinear response of SiC/SiC ceramic matrix composites are reported, wherein the microstructure of the ceramic matrix is captured. This micro scale architecture, which contains free Si material as well as the SiC ceramic, is responsible for residual stresses that play an important role in the subsequent thermo-mechanical behavior of the SiC/SiC composite. Using the novel Multiscale Generalized Method of Cells recursive micromechanics theory, the microstructure of the matrix, as well as the microstructure of the composite (fiber and matrix) can be captured.

  17. Multiscale Modeling of Cortical Neural Networks

    NASA Astrophysics Data System (ADS)

    Torben-Nielsen, Benjamin; Stiefel, Klaus M.

    2009-09-01

    In this study, we describe efforts at modeling the electrophysiological dynamics of cortical networks in a multi-scale manner. Specifically, we describe the implementation of a network model composed of simple single-compartmental neuron models, in which a single complex multi-compartmental model of a pyramidal neuron is embedded. The network is capable of generating Δ (2 Hz, observed during deep sleep states) and γ (40 Hz, observed during wakefulness) oscillations, which are then imposed onto the multi-compartmental model, thus providing realistic, dynamic boundary conditions. We furthermore discuss the challenges and chances involved in multi-scale modeling of neural function.

  18. Multiscale Methods for Nuclear Reactor Analysis

    NASA Astrophysics Data System (ADS)

    Collins, Benjamin S.

    The ability to accurately predict local pin powers in nuclear reactors is necessary to understand the mechanisms that cause fuel pin failure during steady state and transient operation. In the research presented here, methods are developed to improve the local solution using high order methods with boundary conditions from a low order global solution. Several different core configurations were tested to determine the improvement in the local pin powers compared to the standard techniques, that use diffusion theory and pin power reconstruction (PPR). Two different multiscale methods were developed and analyzed; the post-refinement multiscale method and the embedded multiscale method. The post-refinement multiscale methods use the global solution to determine boundary conditions for the local solution. The local solution is solved using either a fixed boundary source or an albedo boundary condition; this solution is "post-refinement" and thus has no impact on the global solution. The embedded multiscale method allows the local solver to change the global solution to provide an improved global and local solution. The post-refinement multiscale method is assessed using three core designs. When the local solution has more energy groups, the fixed source method has some difficulties near the interface: however the albedo method works well for all cases. In order to remedy the issue with boundary condition errors for the fixed source method, a buffer region is used to act as a filter, which decreases the sensitivity of the solution to the boundary condition. Both the albedo and fixed source methods benefit from the use of a buffer region. Unlike the post-refinement method, the embedded multiscale method alters the global solution. The ability to change the global solution allows for refinement in areas where the errors in the few group nodal diffusion are typically large. The embedded method is shown to improve the global solution when it is applied to a MOX/LEU assembly

  19. Preparation and characterization of a novel bioactive restorative composite based on covalently coupled polyurethane-nanohydroxyapatite fibres.

    PubMed

    Khan, A S; Ahmed, Z; Edirisinghe, M J; Wong, F S L; Rehman, I U

    2008-09-01

    Nanohydroxyapatite (n-HAp) was prepared using a sol-gel method. n-HAp powder was obtained from the gel form by heat treatment followed by grinding using ball milling. A novel polyurethane composite material was prepared by chemically binding the hydroxyapatite to the diisocyanate component in the polyurethane backbone through solvent polymerization. The procedure involved the stepwise addition of monomeric units of the polyurethane and optimizing the reagent concentrations. The resultant composite material was electrospun to form fibre mats. The fibres were less than 1mum in thickness and contained no beads or irregularities. Chemical structural characterization of both the ceramics and the novel polymers were carried out by Fourier transform infrared and Raman spectroscopy. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy and Brunauer-Emmett-Teller surface area analysis were also employed to observe the crystal lattice and size and surface area of the n-HAp. Further characterization (by energy-dispersive X-ray analysis and SEM) of the spun fibres revealed the presence of elements associated with hydroxyapatite and polyurethane without the presence of any loose particles of hydroxyapatite, indicating the formation of the covalent bond between the ceramics and the polymer backbone. PMID:18522875

  20. Multi-scale study of soil structure from different genetic horizons: from meter to nanometer

    NASA Astrophysics Data System (ADS)

    Karsanina, Marina; Skvortsova, Elena; Abrosimov, Konstantin; Sizonenko, Timofey; Romanenko, Konstantin; Belokhin, Vasily; Yudina, Anna; Gilyazetdinova, Dina; Korost, Dmitry; Gerke, Kirill

    2016-04-01

    Soil structure is extremely diverse, has numerous relevant scales, e.g., important pore hierarchical levels, such as intra and inter aggregate porosity, cracks and others. None of the existing imaging techniques is capable of catching all scales within one single image due to sample size/resolution limitations. The only way to experimentally obtain soil structural information from all important scales is to utilize multi-scale scanning using different imaging approaches. In this study we use macro X-ray tomography (with resolution of 100 um), micro X-ray tomography (with resolution range of 3-16 um) and SEM with nanoscale resolutions to obtain a vast multi-scale structural data from meter to nanometer. Two one meter long undisturbed soil columns extracted from soddy-podzolic and grey forest soils were used as objects of our multi-scale study. At first macrotomography was used to make the coarsest 3D image of the whole column. Afterwards, the column was carefully sliced to obtain smaller undisturbed samples for microtomography scanning. Some undisturbed soil pieces were also imaged using SEM to obtain sub-micron images of the soil structure. All resulting 2/3D images were segmented using up-to-date image processing and segmentation techniques to obtain solid material and pore space binary phases. Directional correlation functions were utilized to characterize multi-scale soil structures and compare/differentiate them from each other. We extensively show how such powerful structural descriptors as correlation functions can results in better soil structure characterization and classification. Combined with multi-scale image fusion and/or pore-scale modelling techniques 3D multi-scale images can used to assess scale dependant flow and transport properties. This work was partially supported by RFBR grant 15-34-20989 (field studies, X-ray tomography and SEM imaging) and RSF grant 14-17-00658 (directional correlation functions). References: 1. Karsanina, M.V., Gerke, K

  1. Multiscale mapping: Physical concepts and mathematical techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This is an introductory summary for papers either invited or a part of a symposium at the 18th World Congress of Soil Science, July 2006 in Philadelphia. The symposium, titled "Multiscale Mapping of Soil Properties for Environmental Studies, Agriculture, and Decision Making," focused on techniques u...

  2. Multiscale Simulation of Protein Mediated Membrane Remodeling

    PubMed Central

    Ayton, Gary S.; Voth, Gregory A.

    2009-01-01

    Proteins interacting with membranes can result in substantial membrane deformations and curvatures. This effect is known in its broadest terms as membrane remodeling. This review article will survey current multiscale simulation methodologies that have been employed to examine protein-mediated membrane remodeling. PMID:19922811

  3. Multiscale information modelling for heart morphogenesis

    NASA Astrophysics Data System (ADS)

    Abdulla, T.; Imms, R.; Schleich, J. M.; Summers, R.

    2010-07-01

    Science is made feasible by the adoption of common systems of units. As research has become more data intensive, especially in the biomedical domain, it requires the adoption of a common system of information models, to make explicit the relationship between one set of data and another, regardless of format. This is being realised through the OBO Foundry to develop a suite of reference ontologies, and NCBO Bioportal to provide services to integrate biomedical resources and functionality to visualise and create mappings between ontology terms. Biomedical experts tend to be focused at one level of spatial scale, be it biochemistry, cell biology, or anatomy. Likewise, the ontologies they use tend to be focused at a particular level of scale. There is increasing interest in a multiscale systems approach, which attempts to integrate between different levels of scale to gain understanding of emergent effects. This is a return to physiological medicine with a computational emphasis, exemplified by the worldwide Physiome initiative, and the European Union funded Network of Excellence in the Virtual Physiological Human. However, little work has been done on how information modelling itself may be tailored to a multiscale systems approach. We demonstrate how this can be done for the complex process of heart morphogenesis, which requires multiscale understanding in both time and spatial domains. Such an effort enables the integration of multiscale metrology.

  4. Single image defogging by multiscale depth fusion.

    PubMed

    Wang, Yuan-Kai; Fan, Ching-Tang

    2014-11-01

    Restoration of fog images is important for the deweathering issue in computer vision. The problem is ill-posed and can be regularized within a Bayesian context using a probabilistic fusion model. This paper presents a multiscale depth fusion (MDF) method for defog from a single image. A linear model representing the stochastic residual of nonlinear filtering is first proposed. Multiscale filtering results are probabilistically blended into a fused depth map based on the model. The fusion is formulated as an energy minimization problem that incorporates spatial Markov dependence. An inhomogeneous Laplacian-Markov random field for the multiscale fusion regularized with smoothing and edge-preserving constraints is developed. A nonconvex potential, adaptive truncated Laplacian, is devised to account for spatially variant characteristics such as edge and depth discontinuity. Defog is solved by an alternate optimization algorithm searching for solutions of depth map by minimizing the nonconvex potential in the random field. The MDF method is experimentally verified by real-world fog images including cluttered-depth scene that is challenging for defogging at finer details. The fog-free images are restored with improving contrast and vivid colors but without over-saturation. Quantitative assessment of image quality is applied to compare various defog methods. Experimental results demonstrate that the accurate estimation of depth map by the proposed edge-preserved multiscale fusion should recover high-quality images with sharp details. PMID:25248180

  5. Collaboratory for Multiscale Chemical Science (CMCS)

    SciTech Connect

    Allison, Thomas C

    2012-07-03

    This document provides details of the contributions made by NIST to the Collaboratory for Multiscale Chemical Science (CMCS) project. In particular, efforts related to the provision of data (and software in support of that data) relevant to the combustion pilot project are described.

  6. Multiscale likelihood analysis and image reconstruction

    NASA Astrophysics Data System (ADS)

    Willett, Rebecca M.; Nowak, Robert D.

    2003-11-01

    The nonparametric multiscale polynomial and platelet methods presented here are powerful new tools for signal and image denoising and reconstruction. Unlike traditional wavelet-based multiscale methods, these methods are both well suited to processing Poisson or multinomial data and capable of preserving image edges. At the heart of these new methods lie multiscale signal decompositions based on polynomials in one dimension and multiscale image decompositions based on what the authors call platelets in two dimensions. Platelets are localized functions at various positions, scales and orientations that can produce highly accurate, piecewise linear approximations to images consisting of smooth regions separated by smooth boundaries. Polynomial and platelet-based maximum penalized likelihood methods for signal and image analysis are both tractable and computationally efficient. Polynomial methods offer near minimax convergence rates for broad classes of functions including Besov spaces. Upper bounds on the estimation error are derived using an information-theoretic risk bound based on squared Hellinger loss. Simulations establish the practical effectiveness of these methods in applications such as density estimation, medical imaging, and astronomy.

  7. Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media

    NASA Astrophysics Data System (ADS)

    Gao, Kai; Fu, Shubin; Gibson, Richard L.; Chung, Eric T.; Efendiev, Yalchin

    2015-08-01

    It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale medium property variations, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for wave equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic wave propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.

  8. Generalized multiscale finite-element method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media

    SciTech Connect

    Gao, Kai; Fu, Shubin; Gibson, Richard L.; Chung, Eric T.; Efendiev, Yalchin

    2015-04-14

    It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale medium property variations, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for wave equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic wave propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.

  9. Generalized multiscale finite-element method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media

    DOE PAGESBeta

    Gao, Kai; Fu, Shubin; Gibson, Richard L.; Chung, Eric T.; Efendiev, Yalchin

    2015-04-14

    It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale mediummore » property variations, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for wave equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic wave propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.« less

  10. Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media

    SciTech Connect

    Gao, Kai; Fu, Shubin; Gibson, Richard L.; Chung, Eric T.; Efendiev, Yalchin

    2015-08-15

    It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale medium property variations, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for wave equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic wave propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.

  11. Multivariate multiscale complex network analysis of vertical upward oil-water two-phase flow in a small diameter pipe

    NASA Astrophysics Data System (ADS)

    Gao, Zhong-Ke; Yang, Yu-Xuan; Zhai, Lu-Sheng; Dang, Wei-Dong; Yu, Jia-Liang; Jin, Ning-De

    2016-02-01

    High water cut and low velocity vertical upward oil-water two-phase flow is a typical complex system with the features of multiscale, unstable and non-homogenous. We first measure local flow information by using distributed conductance sensor and then develop a multivariate multiscale complex network (MMCN) to reveal the dispersed oil-in-water local flow behavior. Specifically, we infer complex networks at different scales from multi-channel measurements for three typical vertical oil-in-water flow patterns. Then we characterize the generated multiscale complex networks in terms of network clustering measure. The results suggest that the clustering coefficient entropy from the MMCN not only allows indicating the oil-in-water flow pattern transition but also enables to probe the dynamical flow behavior governing the transitions of vertical oil-water two-phase flow.

  12. Multivariate multiscale complex network analysis of vertical upward oil-water two-phase flow in a small diameter pipe.

    PubMed

    Gao, Zhong-Ke; Yang, Yu-Xuan; Zhai, Lu-Sheng; Dang, Wei-Dong; Yu, Jia-Liang; Jin, Ning-De

    2016-01-01

    High water cut and low velocity vertical upward oil-water two-phase flow is a typical complex system with the features of multiscale, unstable and non-homogenous. We first measure local flow information by using distributed conductance sensor and then develop a multivariate multiscale complex network (MMCN) to reveal the dispersed oil-in-water local flow behavior. Specifically, we infer complex networks at different scales from multi-channel measurements for three typical vertical oil-in-water flow patterns. Then we characterize the generated multiscale complex networks in terms of network clustering measure. The results suggest that the clustering coefficient entropy from the MMCN not only allows indicating the oil-in-water flow pattern transition but also enables to probe the dynamical flow behavior governing the transitions of vertical oil-water two-phase flow. PMID:26833427

  13. Multivariate multiscale complex network analysis of vertical upward oil-water two-phase flow in a small diameter pipe

    PubMed Central

    Gao, Zhong-Ke; Yang, Yu-Xuan; Zhai, Lu-Sheng; Dang, Wei-Dong; Yu, Jia-Liang; Jin, Ning-De

    2016-01-01

    High water cut and low velocity vertical upward oil-water two-phase flow is a typical complex system with the features of multiscale, unstable and non-homogenous. We first measure local flow information by using distributed conductance sensor and then develop a multivariate multiscale complex network (MMCN) to reveal the dispersed oil-in-water local flow behavior. Specifically, we infer complex networks at different scales from multi-channel measurements for three typical vertical oil-in-water flow patterns. Then we characterize the generated multiscale complex networks in terms of network clustering measure. The results suggest that the clustering coefficient entropy from the MMCN not only allows indicating the oil-in-water flow pattern transition but also enables to probe the dynamical flow behavior governing the transitions of vertical oil-water two-phase flow. PMID:26833427

  14. Multiscale entanglement in ring polymers under spherical confinement.

    PubMed

    Tubiana, Luca; Orlandini, Enzo; Micheletti, Cristian

    2011-10-28

    The interplay of geometrical and topological entanglement in semiflexible knotted polymer rings confined inside a spherical cavity is investigated by using advanced numerical methods. By using stringent and robust algorithms for locating knots, we characterize how the knot length l(k) depends on the ring contour length L(c) and the radius of the confining sphere R(c). In the no- and strong-confinement cases, we observe weak knot localization and complete knot delocalization, respectively. We show that the complex interplay of l(k), L(c), and R(c) that seamlessly bridges these two limits can be encompassed by a simple scaling argument based on deflection theory. The same argument is used to rationalize the multiscale character of the entanglement that emerges with increasing confinement. PMID:22107680

  15. Multiscale approach to modeling intrinsic dissipation in solids

    NASA Astrophysics Data System (ADS)

    Kunal, K.; Aluru, N. R.

    2016-08-01

    In this paper, we develop a multiscale approach to model intrinsic dissipation under high frequency of vibrations in solids. For vibrations with a timescale comparable to the phonon relaxation time, the local phonon distribution deviates from the equilibrium distribution. We extend the quasiharmonic (QHM) method to describe the dynamics under such a condition. The local deviation from the equilibrium state is characterized using a nonequilibrium stress tensor. A constitutive relation for the time evolution of the stress component is obtained. We then parametrize the evolution equation using the QHM method and a stochastic sampling approach. The stress relaxation dynamics is obtained using mode Langevin dynamics. Methods to obtain the input variables for the Langevin dynamics are discussed. The proposed methodology is used to obtain the dissipation rate Edissip for different cases. Frequency and size effect on Edissip are studied. The results are compared with those obtained using nonequilibrium molecular dynamics (MD).

  16. Multiscale Topographical Analysis of Biogeochemically Reduced Hematite Surfaces

    NASA Astrophysics Data System (ADS)

    Rustad, J.; Rosso, K. M.; Dubuffet, F.; Yuen, D. A.

    2001-12-01

    Establishing the mechanisms and magnitudes of nano-mesoscale influences on interfacial chemical reactivity requires a multiscale description of the structure of the interfacial region. The identification of scaling relationships characterizing mineral surface structure in low-temperature environments is a first step in the construction structure-activity relationships that are potentially applicable over multiple length scales. Using wavelet image processing techniques and scaling relationships such as the evaluation of Hurst exponents and fractal dimension, we systematize and quantify mineral surface topography of a sample of hematite undergoing biochemically induced reductive dissolution. Image mosaicking methods commonly applied in remote sensing and medical imaging contexts are applied to AFM images to obtain large scale images for the evalution of scaling exponents. Gaussian wavelet methods are used to enhance and quantify structural features associated with the biogeochemically reduced surfaces.

  17. Effect of Clay Amounts on Morphology and Mechanical Performances in Multiscale PET Composites

    NASA Astrophysics Data System (ADS)

    Barbosa, C. N.; Chabert, F.; Nassiet, V.; Viana, J. C.; Pereira, P.

    2011-05-01

    This work presents an investigation of the properties of poly(ethylene terephthalate)/glass fibres/nanoclay multiscale composites. The aim is to demonstrate the effect of adding various clay amounts on the morphology and mechanical performance of multiscale PET composites. Multiscale composites were prepared by adding 0.5, 1.0, 3.0, and 5.0 wt% of Cloisite15A montmorillonite: Initially, a masterbatch of pure PET blended with 10 wt% of Cloisite15A was obtained in a co-rotating twin screw extruder. The multiscale composites were then blended, via mechanical mixing, and injection moulded by adding the masterbatch to the glass fibre reinforced matrix. The morphological and mechanical characterizations of all compounds are discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the characteristic (001) peak of the nanocomposite obtained by extrusion (masterbatch) shifted to the lower angle region stating an intercalated structure. However, the subsequent injection moulding process changed the morphological structure of the multiscale nanocomposites reducing the basal distance mostly for small loadings of nanoclay. The addition of nanoclay to PET matrices increases the degree of crystallinity, the clay platelets possibly playing the role of nucleating agent, as revealed by DSC and FTIR. The time relaxation spectra broaden as seen by DMA, as the ratio of clay/polymer interfaces increases. The yield stress of composites with 0.5 and 1 wt% of C15A content are enhanced. For more than 3% of nanoclay, the yield stress decreases. The Young's modulus is increased when adding C15 nanoclay. Indeed, clay exfoliation was not attained, but the intercalated particle dispersion improved the stiffness properties of PET/glass fibres/nanoclay composites.

  18. Physicochemical characterizations of nano-palm oil fuel ash

    NASA Astrophysics Data System (ADS)

    Rajak, Mohd Azrul Abdul; Majid, Zaiton Abdul; Ismail, Mohammad

    2015-07-01

    Palm Oil Fuel Ash (POFA) is known as a good supplementary cementing material due to its siliceous-rich content. The application of nanotechnology in the pozzolanic materials could invent new functions in the efficiency of physical and chemical properties of materials. Thus, the present study aims to generate nano-sized POFA and characterize the physicochemical properties of nano-palm oil fuel ash (nPOFA). The nPOFA was prepared by mechanically grinding micro POFA using a high intensity ball milling for 6 hours. The physicochemical properties of nPOFA were characterized via X-Ray Fluoresence (XRF), Scanning Emission microscopy- Energy Dispersive X-Ray (SEM-EDX), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The particle size of nPOFA acquired from TEM analysis was in the range of 20 nm to 90 nm, while the average crystallite size calculated from XRD diffractogram was 61.5 nm. The resulting nPOFA has a BET surface area of 145.35 m2/g, which is more than 85% increment in surface area compared to micro-sized POFA. The morphology and elemental studies showed the presence of spherical as well as irregularly shaped and fine nPOFA particles contains with high silicon content. The presence of α-quartz as the major phase of the nPOFA was identified through XRD analysis. The study concludes that nPOFA has the potential as a supplementary cementing material due to the high silica content, high surface area and the unique behaviors of nano-structured particles.

  19. Physicochemical characterizations of nano-palm oil fuel ash

    SciTech Connect

    Rajak, Mohd Azrul Abdul; Majid, Zaiton Abdul; Ismail, Mohammad

    2015-07-22

    Palm Oil Fuel Ash (POFA) is known as a good supplementary cementing material due to its siliceous-rich content. The application of nanotechnology in the pozzolanic materials could invent new functions in the efficiency of physical and chemical properties of materials. Thus, the present study aims to generate nano-sized POFA and characterize the physicochemical properties of nano-palm oil fuel ash (nPOFA). The nPOFA was prepared by mechanically grinding micro POFA using a high intensity ball milling for 6 hours. The physicochemical properties of nPOFA were characterized via X-Ray Fluoresence (XRF), Scanning Emission microscopy- Energy Dispersive X-Ray (SEM-EDX), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The particle size of nPOFA acquired from TEM analysis was in the range of 20 nm to 90 nm, while the average crystallite size calculated from XRD diffractogram was 61.5 nm. The resulting nPOFA has a BET surface area of 145.35 m{sup 2}/g, which is more than 85% increment in surface area compared to micro-sized POFA. The morphology and elemental studies showed the presence of spherical as well as irregularly shaped and fine nPOFA particles contains with high silicon content. The presence of α-quartz as the major phase of the nPOFA was identified through XRD analysis. The study concludes that nPOFA has the potential as a supplementary cementing material due to the high silica content, high surface area and the unique behaviors of nano-structured particles.

  20. Effect of milling conditions on solid-state amorphization of glipizide, and characterization and stability of solid forms.

    PubMed

    Xu, Kailin; Xiong, Xinnuo; Zhai, Yuanming; Wang, Lili; Li, Shanshan; Yan, Jin; Wu, Di; Ma, Xiaoli; Li, Hui

    2016-09-10

    In this study, the amorphization of glipizide was systematically investigated through high-energy ball milling at different temperatures. The results of solid-state amorphization through milling indicated that glipizide underwent direct crystal-to-glass transformation at 15 and 25°C and crystal-to-glass-to-crystal conversion at 35°C; hence, milling time and temperature had significant effects on the amorphization of glipizide, which should be effectively controlled to obtain totally amorphous glipizide. Solid forms of glipizide were detailedly characterized through analyses of X-ray powder diffraction, morphology, thermal curves, vibrational spectra, and solid-state nuclear magnetic resonance. The physical stability of solid forms was investigated under different levels of relative humidity (RH) at 25°C. Forms I and III are kinetically stable and do not form any new solid-state forms at various RH levels. By contrast, Form II is kinetically unstable, undergoing direct glass-to-crystal transformation when RH levels higher than 32.8%. Therefore, stability investigation indicated that Form II should be stored under relatively dry conditions to prevent rapid crystallization. High temperatures can also induce the solid-state transformation of Form II; the conversion rate increased with increasing temperature. PMID:27454088

  1. Preparation and characterization of rare earth modified nanocrystalline Al2O3/13 wt%TiO2 feedstock for plasma spraying.

    PubMed

    Wang, Y; Tian, W; Yang, Y

    2009-02-01

    The preparation and characterization of RE modified nanocrystalline Al2O3/13 wt%TiO2 feedstock for plasma spraying are described in this paper. Taking individual nano particles as starting materials, by wet ball milling, spray drying, sintering and plasma treating, nanocrystalline plasma sprayable feedstock is prepared. The as-prepared feedstocks were analyzed by XRD, SEM, EDS, TEM and HRTEM methods. As shown from analyses results, the reconstituted agglomerate feedstock possesses spherical geometry, proper particle size, homogeneous composition distribution and nano scaled grains. There are three dimensional net structures in the prepared feedstock, which could be retained in coatings if the feedstock does not melt or partially melts during the plasma spray process. The three dimensional net structures could play an important role in improving crack propagation resistance and wear resistance of coatings. The reconstitution process and characterization methods discussed in this paper can also be applied to prepare intraclass nanocrystalline feedstock such as ZrO2/Y2O3 and Cr2O3 et al. PMID:19441543

  2. Multiscale modeling of polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Sheidaei, Azadeh

    In recent years, polymer nano-composites (PNCs) have increasingly gained more attention due to their improved mechanical, barrier, thermal, optical, electrical and biodegradable properties in comparison with the conventional micro-composites or pristine polymer. With a modest addition of nanoparticles (usually less than 5wt. %), PNCs offer a wide range of improvements in moduli, strength, heat resistance, biodegradability, as well as decrease in gas permeability and flammability. Although PNCs offer enormous opportunities to design novel material systems, development of an effective numerical modeling approach to predict their properties based on their complex multi-phase and multiscale structure is still at an early stage. Developing a computational framework to predict the mechanical properties of PNC is the focus of this dissertation. A computational framework has been developed to predict mechanical properties of polymer nano-composites. In chapter 1, a microstructure inspired material model has been developed based on statistical technique and this technique has been used to reconstruct the microstructure of Halloysite nanotube (HNT) polypropylene composite. This technique also has been used to reconstruct exfoliated Graphene nanoplatelet (xGnP) polymer composite. The model was able to successfully predict the material behavior obtained from experiment. Chapter 2 is the summary of the experimental work to support the numerical work. First, different processing techniques to make the polymer nanocomposites have been reviewed. Among them, melt extrusion followed by injection molding was used to manufacture high density polyethylene (HDPE)---xGnP nanocomposties. Scanning electron microscopy (SEM) also was performed to determine particle size and distribution and to examine fracture surfaces. Particle size was measured from these images and has been used for calculating the probability density function for GNPs in chapter 1. A series of nanoindentation tests have

  3. International Conference on Multiscale Methods and Partial Differential Equations.

    SciTech Connect

    Thomas Hou

    2006-12-12

    The International Conference on Multiscale Methods and Partial Differential Equations (ICMMPDE for short) was held at IPAM, UCLA on August 26-27, 2005. The conference brought together researchers, students and practitioners with interest in the theoretical, computational and practical aspects of multiscale problems and related partial differential equations. The conference provided a forum to exchange and stimulate new ideas from different disciplines, and to formulate new challenging multiscale problems that will have impact in applications.

  4. Multiscale 3D bioimaging: from cell, tissue to whole organism

    NASA Astrophysics Data System (ADS)

    Lau, S. H.; Wang, Ge; Chandrasekeran, Margam; Fan, Victor; Nazrul, Mohd; Chang, Hauyee; Fong, Tiffany; Gelb, Jeff; Feser, Michael; Yun, Wenbing

    2009-05-01

    While electron microscopes and AFMs are capable of high resolution imaging to molecular levels, there is an ongoing problem in integrating these results into the larger scale structure and functions of tissue and organs within a complex organism. Imaging biological samples with optical microscopy is predominantly done with histology and immunohistochemistry, which can take up to a several weeks to prepare, are artifact prone and only available as individual 2D images. At the nano resolution scale, the higher resolution electron microscopy and AFM are used, but again these require destructive sample preparation and data are in 2D. To bridge this gap, we describe a rapid non invasive hierarchical bioimaging technique using a novel lab based x-ray computed tomography to characterize complex biological organism in multiscale- from whole organ (mesoscale) to calcified and soft tissue (microscale), to subcellular structures, nanomaterials and cellular-scaffold interaction (nanoscale). While MicroCT (micro x-ray computed tomography) is gaining in popularity for non invasive bones and tissue imaging, contrast and resolution are still vastly inadequate compared to histology. In this study we will present multiscale results from a novel microCT and nanoCT (nano x-ray tomography system). The novel MicroCT can image large specimen and tissue sample at histology resolution of submicron voxel resolution, often without contrast agents, while the nanoCT using x-ray optics similar to those used in synchrotron radiation facilities, has 20nm voxel resolution, suitable for studying cellular, subcellular morphology and nanomaterials. Multiscale examples involving both calcified and soft tissue will be illustrated, which include imaging a rat tibia to the individual channels of osteocyte canaliculli and lacunae and an unstained whole murine lung to its alveoli. The role of the novel CT will also be discussed as a possible means for rapid virtual histology using a biopsy of a human

  5. Multiscale Cues Drive Collective Cell Migration

    PubMed Central

    Nam, Ki-Hwan; Kim, Peter; Wood, David K.; Kwon, Sunghoon; Provenzano, Paolo P.; Kim, Deok-Ho

    2016-01-01

    To investigate complex biophysical relationships driving directed cell migration, we developed a biomimetic platform that allows perturbation of microscale geometric constraints with concomitant nanoscale contact guidance architectures. This permits us to elucidate the influence, and parse out the relative contribution, of multiscale features, and define how these physical inputs are jointly processed with oncogenic signaling. We demonstrate that collective cell migration is profoundly enhanced by the addition of contract guidance cues when not otherwise constrained. However, while nanoscale cues promoted migration in all cases, microscale directed migration cues are dominant as the geometric constraint narrows, a behavior that is well explained by stochastic diffusion anisotropy modeling. Further, oncogene activation (i.e. mutant PIK3CA) resulted in profoundly increased migration where extracellular multiscale directed migration cues and intrinsic signaling synergistically conspire to greatly outperform normal cells or any extracellular guidance cues in isolation. PMID:27460294

  6. Multiscale simulation of red blood cell aggregation

    NASA Astrophysics Data System (ADS)

    Bagchi, P.; Popel, A. S.

    2004-11-01

    In humans and other mammals, aggregation of red blood cells (RBC) is a major determinant to blood viscosity in microcirculation under physiological and pathological conditions. Elevated levels of aggregation are often related to cardiovascular diseases, bacterial infection, diabetes, and obesity. Aggregation is a multiscale phenomenon that is governed by the molecular bond formation between adjacent cells, morphological and rheological properties of the cells, and the motion of the extra-cellular fluid in which the cells circulate. We have developed a simulation technique using front tracking methods for multiple fluids that includes the multiscale characteristics of aggregation. We will report the first-ever direct computer simulation of aggregation of deformable cells in shear flows. We will present results on the effect of shear rate, strength of the cross-bridging bonds, and the cell rheological properties on the rolling motion, deformation and subsequent breakage of an aggregate.

  7. Multiscale Community Blockmodel for Network Exploration

    PubMed Central

    Ho, Qirong; Parikh, Ankur P.; Xing, Eric P.

    2013-01-01

    Real world networks exhibit a complex set of phenomena such as underlying hierarchical organization, multiscale interaction, and varying topologies of communities. Most existing methods do not adequately capture the intrinsic interplay among such phenomena. We propose a nonparametric Multiscale Community Blockmodel (MSCB) to model the generation of hierarchies in social communities, selective membership of actors to subsets of these communities, and the resultant networks due to within- and cross-community interactions. By using the nested Chinese Restaurant Process, our model automatically infers the hierarchy structure from the data. We develop a collapsed Gibbs sampling algorithm for posterior inference, conduct extensive validation using synthetic networks, and demonstrate the utility of our model in real-world datasets such as predator-prey networks and citation networks. PMID:24288419

  8. Stochastic multiscale model for carbonate rocks.

    PubMed

    Biswal, B; Oren, P-E; Held, R J; Bakke, S; Hilfer, R

    2007-06-01

    A multiscale model for the diagenesis of carbonate rocks is proposed. It captures important pore scale characteristics of carbonate rocks: wide range of length scales in the pore diameters; large variability in the permeability; and strong dependence of the geometrical and transport parameters on the resolution. A pore scale microstructure of an oolithic dolostone with generic diagenetic features is successfully generated. The continuum representation of a reconstructed cubic sample of side length 2mm contains roughly 42 x 10{6} crystallites and pore diameters varying over many decades. Petrophysical parameters are computed on discretized samples of sizes up to 1000{3}. The model can be easily adapted to represent the multiscale microstructure of a wide variety of carbonate rocks. PMID:17677251

  9. Multiscale perspectives of virus entry via endocytosis

    PubMed Central

    2013-01-01

    Most viruses take advantage of endocytic pathways to gain entry into host cells and initiate infections. Understanding of virus entry via endocytosis is critically important for the design of antiviral strategies. Virus entry via endocytosis is a complex process involving hundreds of cellular proteins. The entire process is dictated by events occurring at multiple time and length scales. In this review, we discuss and evaluate the available means to investigate virus endocytic entry, from both experimental and theoretical/numerical modeling fronts, and highlight the importance of multiscale features. The complexity of the process requires investigations at a systems biology level, which involves the combination of different experimental approaches, the collaboration of experimentalists and theorists across different disciplines, and the development of novel multiscale models. PMID:23734580

  10. Concurrent Multiscale Modeling of Embedded Nanomechanics

    SciTech Connect

    Rudd, R E

    2001-04-13

    We discuss concurrent multiscale simulations of dynamic and temperature-dependent processes found in nanomechanical systems coupled to larger scale surroundings. We focus on the behavior of sub-micron Micro-Electro-Mechanical Systems (MEMS), especially micro-resonators. The coupling of length scales methodology we have developed for MEMS employs an atomistic description of small but key regions of the system, consisting of millions of atoms, coupled concurrently to a finite element model of the periphery. The result is a model that accurately describes the behavior of the mechanical components of MEMS down to the atomic scale. This paper reviews some of the general issues involved in concurrent multiscale simulation, extends the methodology to metallic systems and describes how it has been used to identify atomistic effects in sub-micron resonators.

  11. Multiscale tissue engineering for liver reconstruction

    PubMed Central

    Sudo, Ryo

    2014-01-01

    The liver is a target of in vitro tissue engineering despite its capability to regenerate in vivo. The construction of liver tissues in vitro remains challenging. In this review, conventional 3D cultures of hepatocytes are first discussed. Recent advances in the 3D culturing of liver cells are then summarized in the context of in vitro liver tissue reconstruction at the micro- and macroscales. The application of microfluidics technology to liver tissue engineering has been introduced as a bottom-up approach performed at the microscale, whereas whole-organ bioengineering technology was introduced as a top-down approach performed at the macroscale. Mesoscale approaches are also discussed in considering the integration of micro- and macroscale approaches. Multiple parallel multiscale liver tissue engineering studies are ongoing; however, no tissue-engineered liver that is appropriate for clinical use has yet been realized. The integration of multiscale tissue engineering studies is essential for further understanding of liver reconstruction strategies. PMID:24500493

  12. Multiscale Cues Drive Collective Cell Migration

    NASA Astrophysics Data System (ADS)

    Nam, Ki-Hwan; Kim, Peter; Wood, David K.; Kwon, Sunghoon; Provenzano, Paolo P.; Kim, Deok-Ho

    2016-07-01

    To investigate complex biophysical relationships driving directed cell migration, we developed a biomimetic platform that allows perturbation of microscale geometric constraints with concomitant nanoscale contact guidance architectures. This permits us to elucidate the influence, and parse out the relative contribution, of multiscale features, and define how these physical inputs are jointly processed with oncogenic signaling. We demonstrate that collective cell migration is profoundly enhanced by the addition of contract guidance cues when not otherwise constrained. However, while nanoscale cues promoted migration in all cases, microscale directed migration cues are dominant as the geometric constraint narrows, a behavior that is well explained by stochastic diffusion anisotropy modeling. Further, oncogene activation (i.e. mutant PIK3CA) resulted in profoundly increased migration where extracellular multiscale directed migration cues and intrinsic signaling synergistically conspire to greatly outperform normal cells or any extracellular guidance cues in isolation.

  13. Quantum Mechanics Based Multiscale Modeling of Materials

    NASA Astrophysics Data System (ADS)

    Lu, Gang

    2013-03-01

    We present two quantum mechanics based multiscale approaches that can simulate extended defects in metals accurately and efficiently. The first approach (QCDFT) can treat multimillion atoms effectively via density functional theory (DFT). The method is an extension of the original quasicontinuum approach with DFT as its sole energetic formulation. The second method (QM/MM) has to do with quantum mechanics/molecular mechanics coupling based on the constrained density functional theory, which provides an exact framework for a self-consistent quantum mechanical embedding. Several important materials problems will be addressed using the multiscale modeling approaches, including hydrogen-assisted cracking in Al, magnetism-controlled dislocation properties in Fe and Si pipe diffusion along Al dislocation core. We acknowledge the support from the Office of Navel Research and the Army Research Office.

  14. Multiscale Cues Drive Collective Cell Migration.

    PubMed

    Nam, Ki-Hwan; Kim, Peter; Wood, David K; Kwon, Sunghoon; Provenzano, Paolo P; Kim, Deok-Ho

    2016-01-01

    To investigate complex biophysical relationships driving directed cell migration, we developed a biomimetic platform that allows perturbation of microscale geometric constraints with concomitant nanoscale contact guidance architectures. This permits us to elucidate the influence, and parse out the relative contribution, of multiscale features, and define how these physical inputs are jointly processed with oncogenic signaling. We demonstrate that collective cell migration is profoundly enhanced by the addition of contract guidance cues when not otherwise constrained. However, while nanoscale cues promoted migration in all cases, microscale directed migration cues are dominant as the geometric constraint narrows, a behavior that is well explained by stochastic diffusion anisotropy modeling. Further, oncogene activation (i.e. mutant PIK3CA) resulted in profoundly increased migration where extracellular multiscale directed migration cues and intrinsic signaling synergistically conspire to greatly outperform normal cells or any extracellular guidance cues in isolation. PMID:27460294

  15. Towards multiscale modeling of influenza infection

    PubMed Central

    Murillo, Lisa N.; Murillo, Michael S.; Perelson, Alan S.

    2013-01-01

    Aided by recent advances in computational power, algorithms, and higher fidelity data, increasingly detailed theoretical models of infection with influenza A virus are being developed. We review single scale models as they describe influenza infection from intracellular to global scales, and, in particular, we consider those models that capture details specific to influenza and can be used to link different scales. We discuss the few multiscale models of influenza infection that have been developed in this emerging field. In addition to discussing modeling approaches, we also survey biological data on influenza infection and transmission that is relevant for constructing influenza infection models. We envision that, in the future, multiscale models that capitalize on technical advances in experimental biology and high performance computing could be used to describe the large spatial scale epidemiology of influenza infection, evolution of the virus, and transmission between hosts more accurately. PMID:23608630

  16. Use of QM/DMD as a Multiscale Approach to Modeling Metalloenzymes.

    PubMed

    Gallup, N M; Alexandrova, A N

    2016-01-01

    Enzymes are complex biomolecules capable of performing unique catalysis under physiological conditions at neutral temperature and pH. However, the architecture of enzymatic catalysis is often a combination of the quantum influence of the immediate active site, as well as the electrostatic and configurational influences of amino acids surrounding the active site. As a result of this cooperation between baseline chemical reactivity and electrostatic assistance, it has become important to model enzymes using multiscale methods that take advantage of treating the active site with quantum mechanical methods, while approximately treating the surrounding protein using cheaper, classically driven force-field molecular mechanics methods. Here we describe the use of a multiscale engine which utilizes a combination of density functional theory with discrete molecular dynamics (dubbed QM/DMD) to aid in the characterization of metalloenzymes. PMID:27498643

  17. Multiscale Modeling, Simulation and Visualization and Their Potential for Future Aerospace Systems

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K. (Compiler)

    2002-01-01

    This document contains the proceedings of the Training Workshop on Multiscale Modeling, Simulation and Visualization and Their Potential for Future Aerospace Systems held at NASA Langley Research Center, Hampton, Virginia, March 5 - 6, 2002. The workshop was jointly sponsored by Old Dominion University's Center for Advanced Engineering Environments and NASA. Workshop attendees were from NASA, other government agencies, industry, and universities. The objectives of the workshop were to give overviews of the diverse activities in hierarchical approach to material modeling from continuum to atomistics; applications of multiscale modeling to advanced and improved material synthesis; defects, dislocations, and material deformation; fracture and friction; thin-film growth; characterization at nano and micro scales; and, verification and validation of numerical simulations, and to identify their potential for future aerospace systems.

  18. Multiscale flow in an electro-hydrodynamically driven oil-in-oil emulsion.

    PubMed

    Varshney, Atul; Gohil, Smita; Sathe, Mayur; R V, Seshagiri Rao; Joshi, J B; Bhattacharya, S; Yethiraj, Anand; Ghosh, Shankar

    2016-02-14

    Efficient mixing strategies in a fluid involve generation of multi-scale flows which are strongly suppressed in highly viscous systems. In this work, we report a novel form of multi-scale flow, driven by an external electric field, in a highly viscous (η∼ 1 Pa s) oil-in-oil emulsion system consisting of micron-size droplets. This electro-hydrodynamic flow leads to dynamical organization at spatial scales much larger than that of the individual droplets. We characterize the dynamics associated with these structures by measuring the time variation of the bulk Reynolds stress in a rheometer, as well as through a micro-scale rheometric measurement by probing the spectrum of fluctuations of a thin fiber cantilever driven by these flows. The results display scale invariance in the energy spectra over three decades with a power law reminiscent of turbulent convection. We also demonstrate the mixing efficiency in such micro-scale systems. PMID:26693675

  19. Computational design and multiscale modeling of a nanoactuator using DNA actuation.

    PubMed

    Hamdi, Mustapha

    2009-12-01

    Developments in the field of nanobiodevices coupling nanostructures and biological components are of great interest in medical nanorobotics. As the fundamentals of bio/non-bio interaction processes are still poorly understood in the design of these devices, design tools and multiscale dynamics modeling approaches are necessary at the fabrication pre-project stage. This paper proposes a new concept of optimized carbon nanotube based servomotor design for drug delivery and biomolecular transport applications. The design of an encapsulated DNA-multi-walled carbon nanotube actuator is prototyped using multiscale modeling. The system is parametrized by using a quantum level approach and characterized by using a molecular dynamics simulation. Based on the analysis of the simulation results, a servo nanoactuator using ionic current feedback is simulated and analyzed for application as a drug delivery carrier. PMID:19880974

  20. Multiscale power analysis for heart rate variability

    NASA Astrophysics Data System (ADS)

    Zeng, Peng; Liu, Hongxing; Ni, Huangjing; Zhou, Jing; Xia, Lan; Ning, Xinbao

    2015-06-01

    We first introduce multiscale power (MSP) method to assess the power distribution of physiological signals on multiple time scales. Simulation on synthetic data and experiments on heart rate variability (HRV) are tested to support the approach. Results show that both physical and psychological changes influence power distribution significantly. A quantitative parameter, termed power difference (PD), is introduced to evaluate the degree of power distribution alteration. We find that dynamical correlation of HRV will be destroyed completely when PD>0.7.