Science.gov

Sample records for fine grain fraction

  1. Survival of refractory presolar grain analogs during Stardust-like impact into Al foils: Implications for Wild 2 presolar grain abundances and study of the cometary fine fraction

    NASA Astrophysics Data System (ADS)

    Croat, T. K.; Floss, C.; Haas, B. A.; Burchell, M. J.; Kearsley, A. T.

    2015-08-01

    We present results of FIB-TEM studies of 12 Stardust analog Al foil craters which were created by firing refractory Si and Ti carbide and nitride grains into Al foils at 6.05 km s-1 with a light-gas gun to simulate capture of cometary grains by the Stardust mission. These foils were prepared primarily to understand the low presolar grain abundances (both SiC and silicates) measured by SIMS in Stardust Al foil samples. Our results demonstrate the intact survival of submicron SiC, TiC, TiN, and less-refractory Si3N4 grains. In small (<2 μm) craters that are formed by single grain impacts, the entire impacting crystalline grain is often preserved intact with minimal modification. While they also survive in crystalline form, grains at the bottom of larger craters (>5 μm) are typically fragmented and are somewhat flattened in the direction of impact due to partial melting and/or plastic deformation. The low presolar grain abundance estimates derived from SIMS measurements of large craters (mostly >50 μm) likely result from greater modification of these impactors (i.e., melting and isotopic dilution), due to higher peak temperatures/pressures in these crater impacts. The better survivability of grains in smaller craters suggests that more accurate presolar grain estimates may be achievable through measurement of such craters. It also suggests small craters can provide a complementary method of study of the Wild 2 fine fraction, especially for refractory CAI-like minerals.

  2. Fine Grain Aluminum Superplasticity

    DTIC Science & Technology

    1980-02-01

    time at elevated temperature for 7475 aluminum alloy 5 2 Optical micrographs of 7075 aluminum alloy after exposure to 5160C (960oF) for times...applied to Al-Zn-Mg-Cu ( 7075 Al) alloy. Subsequent developments by Waldman et al. (refs. 8-11) resulted in the demonstration that 7000 series alloys...a number of aluminum alloys. With such a fine grain structure, high temperature deformation character- istics approaching superplastic behavior

  3. FINE GRAIN NUCLEAR EMULSION

    DOEpatents

    Oliver, A.J.

    1962-04-24

    A method of preparing nuclear track emulsions having mean grain sizes less than 0.1 microns is described. The method comprises adding silver nitrate to potassium bromide at a rate at which there is always a constant, critical excess of silver ions. For minimum size grains, the silver ion concentration is maintained at the critical level of about pAg 2.0 to 5.0 during prectpitation, pAg being defined as the negative logarithm of the silver ion concentration. It is preferred to eliminate the excess silver at the conclusion of the precipitation steps. The emulsion is processed by methods in all other respects generally similar to the methods of the prior art. (AEC)

  4. Fine-grained clay fraction (,0.2 {mu}m): An interesting tool to approach the present thermal and permeability state in active geothermal systems

    SciTech Connect

    Patrier, P.; Papapanagiotou, P.; Beaufort, D.; Traineau, H.; Bril, H.

    1992-01-01

    We have investigated by X-ray diffraction the very fine grained secondary minerals (< 0.2 {micro}m) developed in geothermal systems, in relation with their present thermal and permeability state. Because the smallest particles are the most reactive part of a rock, they are the youngest mineral phases of the geothermal fields. This study has been performed on two active geothermal fields: Milos field, Greece (130 < T < 320 C) and Chipilapa field, Salvador (90 < T < 215 C). In the Milos field, the mineralogical composition of the < 0.2 {micro}m clay fraction observed in the reservoir strongly differs from the overlying altered metamorphic schists in the presence of abundant quantities of saponite and talc/saponite interstratified minerals at unusually high temperature. These phases are considered to be kinetically control-led ''metastable'' minerals which rapidly evolve towards actinolite and talc for present temperatures higher than 300 C. Their occurrence is a good indicator of discharge in highly permeable zones. In the geothermal field of Chipilapa, the mineralogical composition of the < 0.2 {micro}m clay fractions fairly agrees with the temperatures presently measured in the wells, whereas several discrepancies may be pointed out from the compositions of coarser clay fractions (< 5 {micro}m) which contain minerals inherited from higher temperature stages. Permeable zones may be evidenced from an increase of expandable components in the interstratified minerals and a decrease of the coherent domain of the unexpandable clay particles (chlorite).

  5. Grain size evolution and fractionation trends in an experimental regolith

    NASA Technical Reports Server (NTRS)

    Horz, F.; Cintala, M. J.; See, T. H.; Cardenas, F.; Thompson, T. D.

    1984-01-01

    The communication of blocky planetary surfaces into fine-grained regoliths was simulated by impacting a fragmental gabbro target 200 times with stainless steel projectiles. It is found that the comminution efficiency of the surfaces changes with time, being highest in the early stages of regolith formation and decreasing gradually. The relationship between mean grain size and cumulative energy is not linear. Individual, fine-grained regolith components can be generated very early from relatively large progenitor fragments without going through intermediate-size fractions. Impact comminution is capable of producing fractionated fines as postulated by Papike et al. (1982). The role of grain-size selective, lateral transport to explain the fractionated nature of lunar regolith fines may have been overestimated in the past.

  6. Making Pure Fine-Grained Inorganic Powder

    NASA Technical Reports Server (NTRS)

    Wood, C.

    1985-01-01

    Sustained arc plasma chemical reactor fabricates very-fine-grained inorganic solids having low thermal conductivity. Powder fabrication method, based on plasma tube technique produces pure solids without contamination commonly produced by grinding.

  7. Texture measurements in fine grained polyphase aggregates

    NASA Astrophysics Data System (ADS)

    Kilian, R.; Heilbronner, R.; Stünitz, H.

    2009-04-01

    When analyzing natural and experimental microstructures, we routinely use the two methods for orientation imaging and texture measurements: (a) the computer-integrated polarization microscopy (CIP, Panozzo Heilbronner & Pauli, 1993) and (b) the electron back scatter diffractometry (EBSD, e.g. Kunze et al., 1994). The CIP method yields orientation maps and pole figures of c-axes (of uni-axial materials), while the EBSD method yields complete textural data for all crystallographic orientations. In order to compare the orientation images the Euler maps (obtained from EBSD) are recalculated and presented with the more intuitive colour look-up tables (CLUTs) of the CIP method. In this contribution we compare and contrast the results achieved by these two methods using two different samples taken from a metagranodiorite (Kilian et al., 2009): (1) a coarse grained mylonitic rock with polycrystalline quartz aggregates and (2) a very fine grained ultramylonitic rock with single quartz grains dispersed in a polymineralic matrix. For the coarse grained sample (1) both methods yield the same (strong) c-axis pole figure: the geometry of the c-axis polefigure as well as the texture intensity (maximum of polefigure) are identical. The texture of sample (2) - where small quartz grains are dispersed in the polymineralic matrix - is very weak to random. The CIP and EBSD c-axis pole figures are different and - as noted previously - these differences arise from a machine specific bias of the EBSD (Schmocker 2002). In addition to texture analysis, both methods are capable of image segmentation (identification and separation of individual grains in the orientation image) as well as shape and grain size analysis. However due to the entirely different approach taken, the results may differ significantly. For example, when deriving the grain size distribution for sample (2) EBSD (combined with with the OIM® analysis software) yields a positively skewed histogram (with the mode occurring

  8. Fine-Grained Auditory Discrimination: Factor Structures.

    ERIC Educational Resources Information Center

    Elliott, Lois L.; Hammer, Michael A.

    1993-01-01

    This study, with 161 children with and without language learning problems, tested the hypothesis that as children's language development matures, factor-analytic structural changes occur that are associated with measurements of fine-grained auditory discrimination, receptive vocabulary, receptive language, speech production, and 3 performance…

  9. Synthesis of fine-grained TATB

    DOEpatents

    Lee, Kien-Yin; Kennedy, James E.

    2003-04-15

    A method for producing fine-grained triamino-trinitrobenzene (TATB) powders having improved detonation-spreading performance and hence increased shock sensitivity when compared with that for ultrafine TATB is described. A single-step, sonochemical amination of trichloro-trinitrobenzene using ammonium hydroxide solution in a sealed vessel yields TATB having approximately 6 .mu.m median particle diameter and increased shock sensitivity.

  10. Communication Optimizations for Fine-Grained UPCApplications

    SciTech Connect

    Chen, Wei-Yu; Iancu, Costin; Yelick, Katherine

    2005-07-08

    Global address space languages like UPC exhibit high performance and portability on a broad class of shared and distributed memory parallel architectures. The most scalable applications use bulk memory copies rather than individual reads and writes to the shared space, but finer-grained sharing can be useful for scenarios such as dynamic load balancing, event signaling, and distributed hash tables. In this paper we present three optimization techniques for global address space programs with fine-grained communication: redundancy elimination, use of split-phase communication, and communication coalescing. Parallel UPC programs are analyzed using static single assignment form and a data flow graph, which are extended to handle the various shared and private pointer types that are available in UPC. The optimizations also take advantage of UPC's relaxed memory consistency model, which reduces the need for cross thread analysis. We demonstrate the effectiveness of the analysis and optimizations using several benchmarks, which were chosen to reflect the kinds of fine-grained, communication-intensive phases that exist in some larger applications. The optimizations show speedups of up to 70 percent on three parallel systems, which represent three different types of cluster network technologies.

  11. Method of making fine-grained triaminotrinitrobenzene

    DOEpatents

    Benziger, Theodore M.

    1984-01-01

    A method of forming a fine-grained species of the insensitive high explosive sym-triaminotrinitrobenzene (TATB) without grinding. In accordance with the method, 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) is aminated by reaction with gaseous ammonia in an emulsion of toluene in water. The ratio of water to toluene in the emulsion is selected so that toluene is the dispersed phase in the emulsion. The size of the dispersed TCTNB-containing toluene droplets determines the particle size of the resulting TATB. The emulsion is preferably formed with an emulsifier such as ammonium oleate, which may be generated in situ from oleic acid, and stabilized with a protective colloid such as polyvinyl alcohol.

  12. Method of making fine-grained triaminotrinitrobenzene

    DOEpatents

    Benziger, T.M.

    1983-07-26

    A method is given for forming a fine-grained species of the insensitive high explosive sym-triaminotrinitrobenzene (TATB) without grinding. In accordance with the method, 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) is aminated by reaction with gaseous ammonia in an emulsion of toluene in water. The ratio of water to toluene in the emulsion is selected so that toluene is the dispersed phase in the emulsion. The size of the dispersed TCTNB-containing toluene droplets determines the particle size of the resulting TATB. The emulsion is preferably formed with an emulsifier such as ammonium oleate, which may be generated in situ from oleic acid, and stabilized with a protective colloid such as polyvinyl alcohol.

  13. Insights into the fine-grained fraction of serpentine mud from the Southern Chamorro seamount (ODP Leg 195): A combined XRD, RFA and TEM-EDS study

    NASA Astrophysics Data System (ADS)

    Lischka, M.; Meschede, M.; Warr, L. N.

    2009-12-01

    Serpentine mud volcanoes in the outer forearc of the Izu-Bonin-Mariana subduction system occur in a restricted zone, 50km - 120 km away from the trench axis [Fryer et al., 1985]. The morphotectonic elements of the forearc are dominated by horst and graben structures, caused by extensional movements and normal fault systems related to seamount subduction [Fryer et al., 2000; Stern and Smooth, 1998]. These faults may provide conduits for the diapiric uprising of low density serpentine, extruding at the seafloor in stratovolcanic like structures. Released fluids from the subducted slab at estimated depths of approximately 30km are considered to hydrate the forearc mantle wedge along those fractures [Benton et al., 2001; Mottl et al., 2003; Rübke et al., 2004]. During the formation of the fault gouge, serpentine-bodies entrained xenoliths and xenocrysts from the surrounding rocks and are exhumed towards the surface [Fryer et al., 1990]. In our investigation we focus on the silty to clay-sized particle fraction of the serpentine mud matrix, drilled during ODP Leg 195 at site 1200E. We analysed the bulk mineral composition with X-ray diffraction methods on random powder samples, supplemented by X-ray fluorescence measurements on 25 samples. To obtain more insights into the mineralogy fabric and microstructure of the samples, electron microscopy and electron dispersive spectroscopy were used to determine the crystal-chemistry and alteration textures. Particular emphasis was given on determining serpentine polymorphs and the nature of other phyllosilicates and their geochemical composition and constraints. Geochemical observation of the secondary mineral phases should allow us to reconstruct the processes linked with the migration of fluids and volatile components during subduction related metamorphism affecting the mantle wedge. Based on the new data we characterize the conditions of alteration products within a subduction factory, related to the diapiric deposition of

  14. Fine-grained representation learning in convolutional autoencoders

    NASA Astrophysics Data System (ADS)

    Luo, Chang; Wang, Jie

    2016-03-01

    Convolutional autoencoders (CAEs) have been widely used as unsupervised feature extractors for high-resolution images. As a key component in CAEs, pooling is a biologically inspired operation to achieve scale and shift invariances, and the pooled representation directly affects the CAEs' performance. Fine-grained pooling, which uses small and dense pooling regions, encodes fine-grained visual cues and enhances local characteristics. However, it tends to be sensitive to spatial rearrangements. In most previous works, pooled features were obtained by empirically modulating parameters in CAEs. We see the CAE as a whole and propose a fine-grained representation learning law to extract better fine-grained features. This representation learning law suggests two directions for improvement. First, we probabilistically evaluate the discrimination-invariance tradeoff with fine-grained granularity in the pooled feature maps, and suggest the proper filter scale in the convolutional layer and appropriate whitening parameters in preprocessing step. Second, pooling approaches are combined with the sparsity degree in pooling regions, and we propose the preferable pooling approach. Experimental results on two independent benchmark datasets demonstrate that our representation learning law could guide CAEs to extract better fine-grained features and performs better in multiclass classification task. This paper also provides guidance for selecting appropriate parameters to obtain better fine-grained representation in other convolutional neural networks.

  15. Process for preparing fine grain silicon carbide powder

    DOEpatents

    Wei, G.C.

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

  16. Selective Convolutional Descriptor Aggregation for Fine-Grained Image Retrieval.

    PubMed

    Wei, Xiu-Shen; Luo, Jian-Hao; Wu, Jianxin; Zhou, Zhi-Hua

    2017-03-27

    Deep convolutional neural network models pretrained for the ImageNet classification task have been successfully adopted to tasks in other domains, such as texture description and object proposal generation, but these tasks require annotations for images in the new domain. In this paper, we focus on a novel and challenging task in the pure unsupervised setting: fine-grained image retrieval. Even with image labels, fine-grained images are difficult to classify, let alone the unsupervised retrieval task. We propose the Selective Convolutional Descriptor Aggregation (SCDA) method. SCDA firstly localizes the main object in fine-grained images, a step that discards the noisy background and keeps useful deep descriptors. The selected descriptors are then aggregated and dimensionality reduced into a short feature vector using the best practices we found. SCDA is unsupervised, using no image label or bounding box annotation. Experiments on six fine-grained datasets confirm the effectiveness of SCDA for fine-grained image retrieval. Besides, visualization of the SCDA features shows that they correspond to visual attributes (even subtle ones), which might explain SCDA's high mean average precision in fine-grained retrieval. Moreover, on general image retrieval datasets, SCDA achieves comparable retrieval results with state-of-the-art general image retrieval approaches.

  17. Fine-grained zirconium-base material

    DOEpatents

    Van Houten, G.R.

    1974-01-01

    A method is described for making zirconium with inhibited grain growth characteristics, by the process of vacuum melting the zirconium, adding 0.3 to 0.5% carbon, stirring, homogenizing, and cooling. (Official Gazette)

  18. Creep of Fine-grained Gabbro in dry Condition

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Rybacki, E.; Dresen, G.; He, C.

    2008-12-01

    Natural fine-grained gabbro were deformed at 300MPa confining pressure in a paterson-type deformation apparatus in GFZ. Creep tests were performed at temperatures ranging from 950-1150'C, stresses from 25-500 MPa, and strain rates between2.3x10-4 to 6.7x10-8s-1. The fine-grained gabbro is composed of 60 vol percent plagioclase, 30 vol percent pyroxene, 10 vol percent magnetite and ilmenite. The samples were dried at 1000`C for 167 hours before experiments. FTIR measurements show a water content of 0.008 wt percent H2O for starting samples, and 0.03 wt percent H2O for deformed samples. We performed three kinds of tests: stress step creep tests, temperature step creep test and constant stress creep with a long creep time. The data of stress-stepping creep tests and the constant stress creep test with long creep time show that the strain rates under the same stress level were increasing with cumulated creep time beyond a threshold time, which is 24 hours for temperature up to 1050 `C and 5 hours for temperature of 1100 `C, and a linear relation with slope of 1.0 was found between logarithm of strain rate and logarithm of accumulated time, suggesting time-proportional strain-rate enhancement, or equivalently, time-weakening effect of flow strength. Microstructural observations of deformed samples show that melt films occurred between grain boundaries of samples, and the melt contents increase with the creep time, indicating the mechanism of the weakening behavior. The strain rate enhancement related to melt fraction agrees to the data of Dimanov et al. [2000], and is fitted well with the model of Paterson [2000]. In order to determine a steady-state flow law with the effect of melt film excluded, the original steady-state strain rates are converted to the case with t=24 hours for experiments with temperatures up to 1050 `C, and data for temperature of 1100 `C are converted to the case with t=5 hours. The time-corrected creep data were fitted to the most commonly used

  19. Effect of grain moisture content during milling on pasting profile and functional properties of amaranth fractions.

    PubMed

    Kumar, K Vishnuswamy Preetham; Dharmaraj, Usha; Sakhare, Suresh D; Inamdar, Aashitosh A

    2016-05-01

    Evaluation of functional properties of milled fractions of grain amaranth may be useful to decide the end uses of the grain. Hence, pasting profiles of amaranth fractions obtained by milling the grains at different moisture contents were studied in relation with their starch profile and also with their swelling power and solubility indices. It was observed that, for flour fraction, the viscosity parameters were lowest at 14-16 % moisture content. Swelling power and solubility indices of the samples varied as a function of grain moisture content. The middling fraction also showed similar pasting pattern with the variation of grain moisture content. The seed coat fractions showed higher gelatinization temperature compared to that of fine flour and middling fractions. However, starch content of the fine seed coat fraction was comparable with that of the flour and middling fractions. The coarse seed coat fraction showed lower viscosity parameters than the other samples. Viscosity parameters correlated well among themselves while, they did not show significant correlation with the starch content. However, the viscosity parameters showed negative correlation with the soluble amylose content. The study revealed that, the fractions obtained by milling the grains at different moisture content show differential pasting profiles and functional properties.

  20. Characterization of Martian Soil Fines Fraction in SNC Meteorites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, D. S.

    2003-01-01

    Some impact-melt glasses in shergottite meteorites contain large abundances of martian atmospheric noble gases with high (129)Xe/(132)Xe ratios, accompanied by varying (87)Sr/(86)Sr (initial) ratios. These glasses contain Martian Soil Fines (MSF) probably from young volcanic terrains such as Tharsis or Elysium Mons. The composition of the MSF bearing samples is different from the average bulk composition of the host rock. These samples show the following charecteristics: a) simultaeneous enrichment of the felsic component and depletion of the mafic component relative to the host phase and b) significant secondary sulfur/sulfate excesses over the host material. The degree of enrichment and associated depletion varies from one sample to another. Earlier, we found large enrichments of felsic (Al, Ca, Na and K) component and depletion of mafic (Fe, Mg, Mn and Ti) component in several impact melt glass veins and pods of samples ,77 ,78 , 18, and ,20A in EET79001 accompanied by large sulfur/sulfate excesses. Based on these results, we proposed a model where the comminution of basaltic rocks takes place by meteoroid bombardment on the martian surface, leading to the generation of fine-grained soil near the impact sites. This fine-grained soil material is subsequently mobilized by saltation and deflation processes on Mars surface due to pervasive aeolian activity. This movement results in mechanical fractionation leading to the felsic enrichment and mafic depletion in the martian dust. We report, here, new data on an impact-melt inclusion ,507 (PAPA) from EET79001, Lith B and ,506 (ALPHA) from EET79001, Lith A and compare the results with those obtained on Shergotty impact melt glass (DBS).

  1. Fine-grained sediment dispersal along the California coast

    USGS Publications Warehouse

    Warrick, Jonathan A.; Storlazzi, Curt D.

    2013-01-01

    Fine-grained sediment (silt and clay) enters coastal waters from rivers, eroding coastal bluffs, resuspension of seabed sediment, and human activities such as dredging and beach nourishment. The amount of sediment in coastal waters is an important factor in ocean ecosystem health, but little information exists on both the natural and human-driven magnitudes of fine-grained sediment delivery to the coastal zone, its residence time there, and its transport out of the system—information upon which to base environmental assessments. To help fill these information gaps, the U.S. Geological Survey has partnered with Federal, State, and local agencies to monitor fine-grained sediment dispersal patterns and fate in the coastal regions of California. Results of these studies suggest that the waves and currents of many of the nearshore coastal settings of California are adequately energetic to transport fine-grained sediment quickly through coastal systems. These findings will help with the management and regulation of fine-grained sediment along the U.S. west coast.

  2. Fine-grained aggregates in L3 chondrites

    NASA Astrophysics Data System (ADS)

    Watanabe, S.; Kitamura, M.; Morimoto, N.

    1987-12-01

    The textures and chemical compositions of the constituent minerals of the fine-grained aggregates (FGAs) of L3 chondrites were studied by the backscattered electron image technique, electron probe microanalysis, and transmission electron microscopy. Plagioclase and glass in the interstices between fine grains of olivine and pyroxene indicate that the FGAs once partly melted. Compositional zoning and decomposition texture of pyroxenes are similar to those observed in chondrules, indicating a common cooling history of the FGAs and chondrules. Therefore, the mechanism that caused melting of the FGAs is considered to be the same as for chondrules. Bulk compositions of the FGAs are within the range of those of chondrules, so some chondrules probably were produced by complete melting of the same precursor materials as those of the FGAs. The precursor materials must have included fine olivine and other grains that probably are condensates.

  3. Process development for producing fine-grain casting in space

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Malik, R. K.

    1975-01-01

    Assessment of grain growth kinetics at temperatures near the melting point and investigation into the use of potential nucleating agents in combination with the naturally occurring BeO led to the definition of critical low-g experiments which would help to determine whether one or both of these possibilities are valid and whether space processing would be able to yield fine grain ingot beryllium.

  4. Fullerene fine particles adhere to pollen grains and affect their autofluorescence and germination.

    PubMed

    Aoyagi, Hideki; Ugwu, Charles U

    2011-01-01

    Adhesion of commercially produced fullerene fine particles to Cryptomeria japonica, Chamaecyparis obtusa and Camellia japonica pollen grains was investigated. The autofluorescence of pollen grains was affected by the adhesion of fullerene fine particles to the pollen grains. The degree of adhesion of fullerene fine particles to the pollen grains varied depending on the type of fullerene. Furthermore, germination of Camellia japonica pollen grains was inhibited by the adhesion of fullerene fine particles.

  5. Luminescence dating of glacial deposits near the eastern Himalayan syntaxis using different grain-size fractions

    NASA Astrophysics Data System (ADS)

    Hu, Gang; Yi, Chao-Lu; Zhang, Jia-Fu; Liu, Jin-Hua; Jiang, Tao

    2015-09-01

    Numerical dating of glacial deposits is important for understanding Quaternary glacial evolution. Optically stimulated luminescence (OSL) dating is one of the techniques widely used on such sediments. Owing to the short distances traveled before deposition, the incomplete bleaching of luminescence signals in glacial sediments may introduce serious dating problems vis-à-vis glacial and any associated sediments. Here, we report a comparison of OSL ages obtained from the fine (4-11 μm) and medium (38-63 μm) grain size fractions of quartz extracted from glaciofluvial sediments and from glacial tills in the Basongcuo catchment near the eastern Himalayan syntaxis. Initially, four glacial stages were identified based on field observations of moraine distribution and geomorpho-stratigraphic relations. A total of 39 OSL samples were then collected from glaciofluvial sand layers or lenses and from till. Quartz grains in the fine (4-11 μm) and medium (38-63 μm) size fractions were extracted from each sample, and dated using the single-aliquot regeneration (SAR) protocol. The modern supraglacial sediment sample was dated to ˜0.2 (fine grain) to ˜0.7 (medium grain) ka, suggesting that the sediment was not completely bleached on deposition. Contrary to previous experience suggesting that coarse grains are usually better bleached than fine grains prior to deposition, our results show that estimated OSL ages for fine grains are generally younger than those for medium grains. This suggests that the two fractions may have come from different sources and thus have different bleaching histories, and that fine-grained quartz may be more suitable for OSL dating of these materials. Applying the minimum age model to data from medium-grained quartz yields ages close to those obtained from fine-grained quartz, suggesting that both can be used for dating glacial advances. The OSL dates suggest that glaciers in the studied area advanced at 0.1-1.3 ka, ˜7.5 ka and 11-13 ka, and were

  6. Resonance interaction in LBNE fine-grained-tracker near detector

    SciTech Connect

    Duyang, Hongyue; Tian, Xinchun; Mishra, Sanjib R.

    2015-10-15

    This talk is devoted to resonance interaction (RES) in the proposed fine-grained tracker detector (FGT) for LBNE experiment. We use fast MC to study the sensitivity of FGT to RES, and use this measurement as a handle to constrain nuclear effects. Similar analysis is performed on NOMAD data for validation and better understanding. Preliminary RES measurement result using NOMAD data will be reported.

  7. Process for preparing fine-grain metal carbide powder

    DOEpatents

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

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

  8. Authentic Attributes with Fine-Grained Anonymity Protection

    DTIC Science & Technology

    2000-01-01

    on-line advertising rm DoubleClick and consumer data company Abacus Direct was \\the most danger- ous assault against anonymity on the Internet since...registrations and ecommerce trans- Preprint - 2 Stuart G. Stubblebine, and Paul F. Syverson. Authentic Attributes with Fine-Grained Anonymity Protection...Brother, Big `Fun’ at Amazon", Wired News, Aug. 25, 1999. www.wired.com/news/news/ business /story/21417.html [18] David Mazieres and M. Frans Kaashoek. \\The

  9. Critical Technology Assessment: Fine Grain, High Density Graphite

    DTIC Science & Technology

    2010-04-01

    Control Classification Number ( ECCN ) 1C107.a on the Commerce Control List (CCL). The parameters of 1C107.a stem from controls established by the Missile...Technology Control Regime (MTCR). In this assessment, BIS specifically examined: • The application of ECCN 1C107.a and related licensing...export licensing process for fine grain, high density graphite controlled by ECCN 1C107.a, especially to China, requires more license conditions and

  10. Grain Boundary Sliding in Ultra-fine Grained 5083 Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Sung, Ming-Je

    Quantitative measurement and analysis of grain boundary sliding in Ultra-fine grained 5083 Aluminium by AFM was conducted at 623K. The grain size of as received cryomilled Ultra-fine Grained Aluminium was characterized by AFM and TEM, and the average was founded to be about 300nm. Ion beam polishing / etching technology was used to reveal grain boundaries for AFM characterization. The vertical offset of grain boundary sliding was measured by comparing pre-defoemation and post-deformation AFM images. By analyzing these measurements, the contribution of grain boundary sliding to the total strain was estimated as 22% - 52% at a strain rate of 10 -4 /sec -5x10-2/sec. It was demonstrated that the relatively low value of the contribution of grain boundary sliding to the total strain is most likely the result of testing under experimental condition that favor the dominance of region I ( low stress) of the sigmoidal behavior characterizing high strain rate superplasticity, which was previously reported.

  11. Decoding the neural representation of fine-grained conceptual categories.

    PubMed

    Ghio, Marta; Vaghi, Matilde Maria Serena; Perani, Daniela; Tettamanti, Marco

    2016-05-15

    Neuroscientific research on conceptual knowledge based on the grounded cognition framework has shed light on the organization of concrete concepts into semantic categories that rely on different types of experiential information. Abstract concepts have traditionally been investigated as an undifferentiated whole, and have only recently been addressed in a grounded cognition perspective. The present fMRI study investigated the involvement of brain systems coding for experiential information in the conceptual processing of fine-grained semantic categories along the abstract-concrete continuum. These categories consisted of mental state-, emotion-, mathematics-, mouth action-, hand action-, and leg action-related meanings. Thirty-five sentences for each category were used as stimuli in a 1-back task performed by 36 healthy participants. A univariate analysis failed to reveal category-specific activations. Multivariate pattern analyses, in turn, revealed that fMRI data contained sufficient information to disentangle all six fine-grained semantic categories across participants. However, the category-specific activity patterns showed no overlap with the regions coding for experiential information. These findings demonstrate the possibility of detecting specific patterns of neural representation associated with the processing of fine-grained conceptual categories, crucially including abstract ones, though bearing no anatomical correspondence with regions coding for experiential information as predicted by the grounded cognition hypothesis.

  12. Fine-Grained Turbidites: Facies, Attributes and Process Implications

    NASA Astrophysics Data System (ADS)

    Stow, Dorrik; Omoniyi, Bayonle

    2016-04-01

    Within turbidite systems, fine-grained sediments are still the poor relation and sport several contrasting facies models linked to process of deposition. These are volumetrically the dominant facies in deepwater and, from a resource perspective, they form important marginal and tight reservoirs, and have great potential for unconventional shale gas, source rocks and seals. They are also significant hosts of metals and rare earth elements. Based on a large number of studies of modern, ancient and subsurface systems, including 1000s of metres of section logging, we define the principal genetic elements of fine-grained deepwater facies, present a new synthesis of facies models and their sedimentary attributes. The principal architectural elements include: non-channelised slope-aprons, channel-fill, channel levee and overbank, turbidite lobes, mass-transport deposits, contourite drifts, basin sheets and drapes. These comprise a variable intercalation of fine-grained facies - thin-bedded and very thin-bedded turbidites, contourites, hemipelagites and pelagites - and associated coarse-grained facies. Characteristic attributes used to discriminate between these different elements are: facies and facies associations; sand-shale ratio, sand and shale geometry and dimensions, sand connectivity; sediment texture and small-scale sedimentary structures; sediment fabric and microfabric; and small-scale vertical sequences of bed thickness. To some extent, we can relate facies and attribute characteristics to different depositional environments. We identify four distinct facies models: (a) silt-laminated mud turbidites, (b) siliciclastic mud turbidites, (c) carbonate mud turbidites, (d) disorganized silty-mud turbidites, and (e) hemiturbidites. Within the grainsize-velocity matrix turbidite plot, these all fall within the region of mean size < 0.063mm, maximum grainsize (one percentile) <0.2mm, and depositional velocity 0.1-0.5 m/s. Silt-laminated turbidites and many mud

  13. Importance of Pore Size Distribution of Fine-grained Sediments on Gas Hydrate Equilibrium

    NASA Astrophysics Data System (ADS)

    Kwon, T. H.; Kim, H. S.; Cho, G. C.; Park, T. H.

    2015-12-01

    Gas hydrates have been considered as a new source of natural gases. For the gas hydrate production, the gas hydrate reservoir should be depressurized below the equilibrium pressure of gas hydrates. Therefore, it is important to predict the equilibrium of gas hydrates in the reservoir conditions because it can be affected by the pore size of the host sediments due to the capillary effect. In this study, gas hydrates were synthesized in fine-grained sediment samples including a pure silt sample and a natural clayey silt sample cored from a hydrate occurrence region in Ulleung Basin, East Sea, offshore Korea. Pore size distributions of the samples were obtained by the nitrogen adsorption and desorption test and the mercury intrusion porosimetry. The equilibrium curve of gas hydrates in the fine-grained sediments were found to be significantly influenced by the clay fraction and the corresponding small pores (>50 nm in diameter). For the clayey silt sample, the equilibrium pressure was higher by ~1.4 MPa than the bulk equilibrium pressure. In most cases of oceanic gas hydrate reservoirs, sandy layers are found interbedded with fine-grained sediment layers while gas hydrates are intensively accumulated in the sandy layers. Our experiment results reveal the inhibition effect of fine-grained sediments against gas hydrate formation, in which greater driving forces (e.g., higher pressure or lower temperature) are required during natural gas migration. Therefore, gas hydrate distribution in interbedded layers of sandy and fine-grained sediments can be explained by such capillary effect induced by the pore size distribution of host sediments.

  14. Fine-grained hodoscopes based on scintillating optical fibers

    NASA Astrophysics Data System (ADS)

    Borenstein, S. R.; Strand, R. C.

    In order to exploit the high event rates at ISABELLE, it will be necessary to have fast detection with fine spatial resolution. The authors are currently constructing a prototype fine grained hodoscope, the elements of which are scintillating optical fibers. The fibers have been drawn from commercially available plastic scintillator which has been clad with a thin layer of silicone. So far it has been demonstrated with one mm diameter fibers, that with a photodetector at each end, the fibers are more than 99% efficient for lengths of about 60 cm. The readout will be accomplished either with small diameter photomultiplier tubes or avalanche photodiodes used either in the linear or Geiger mode. The program of fiber development and evaluation will be described. The status of the APD as a readout element will be discussed. Finally, an optical encoding readout scheme will be described for events of low multiplicity.

  15. Fine-grained hodoscopes based on scintillating optical fibers

    NASA Astrophysics Data System (ADS)

    Borenstein, S. R.; Strand, R. C.

    In order to exploit the high event rates at ISABELLE, it is necessary to have fast detection with fine spatial resolution. A prototype fine-grained hodoscope, the elements of which are scintillating optical fibers, is currently being constructed. The fibers were drawn from commercially available plastic scintillator which has been clad with a thin layer of silicone. It was demonstrated with one mm diameter fibers that with a photo-detector at each end, the fibers are more than 99% efficient for lengths of about 60 cm. The readout will be accomplished either with small diameter photomultiplier tubes or avalanche photodiodes (APD) used either in the linear or Geiger mode. The program of fiber development and evaluation is described. The status of the APD as a readout element is discussed, and an optical encoding readout scheme is described for events of low multiplicity.

  16. Physics sensitivity studies of Fine-Grained Tracker

    SciTech Connect

    Tian, Xinchun; Mishra, Sanjib R.; Petti, Roberto; Hongyue, Duyang

    2015-10-15

    The reference design of the near detector for the LBNE experiment is a high-resolution Fine-Grained Tracker (FGT). We performed sensitivity studies – critical to constraining the systematics in oscillation searches – of measurements of (1) the absolute neutrino flux, (2) neutrino-nucleon quasi-elastic (QE) and (3) resonance (Res) interactions. In QE and Res emphasis is laid in identifying in situ measurables that help constrain nuclear effects such as initial state pair wise correlations and final state interactions.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  18. Primitive Fine-Grained Matrix in the Unequilbrated Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Weisberg, M. K.; Zolensky, M. E.; Kimura, M.; Ebel, D. S.

    2014-01-01

    Enstatite chondrites (EC) have important implications for constraining conditions in the early solar system and for understanding the evolution of the Earth and other inner planets. They are among the most reduced solar system materials as reflected in their mineral compositions and assemblage. They are the only chondrites with oxygen as well as Cr, Ti, Ni and Zn stable isotope compositions similar to the earth and moon and most are completely dry, lacking any evidence of hydrous alteration; the only exception are EC clasts in the Kaidun breccia which have hydrous minerals. Thus, ECs likely formed within the snow line and are good candidates to be building blocks of the inner planets. Our goals are to provide a more detailed characterization the fine-grained matrix in E3 chondrites, understand its origin and relationship to chondrules, decipher the relationship between EH and EL chondrites and compare E3 matrix to matrices in C and O chondrites as well as other fine-grained solar system materials. Is E3 matrix the dust remaining from chondrule formation or a product of parent body processing or both?

  19. PRAM C:a new programming environment for fine-grain and coarse-grain parallelism.

    SciTech Connect

    Brown, Jonathan Leighton; Wen, Zhaofang.

    2004-11-01

    In the search for ''good'' parallel programming environments for Sandia's current and future parallel architectures, they revisit a long-standing open question. Can the PRAM parallel algorithms designed by theoretical computer scientists over the last two decades be implemented efficiently? This open question has co-existed with ongoing efforts in the HPC community to develop practical parallel programming models that can simultaneously provide ease of use, expressiveness, performance, and scalability. Unfortunately, no single model has met all these competing requirements. Here they propose a parallel programming environment, PRAM C, to bridge the gap between theory and practice. This is an attempt to provide an affirmative answer to the PRAM question, and to satisfy these competing practical requirements. This environment consists of a new thin runtime layer and an ANSI C extension. The C extension has two control constructs and one additional data type concept, ''shared''. This C extension should enable easy translation from PRAM algorithms to real parallel programs, much like the translation from sequential algorithms to C programs. The thin runtime layer bundles fine-grained communication requests into coarse-grained communication to be served by message-passing. Although the PRAM represents SIMD-style fine-grained parallelism, a stand-alone PRAM C environment can support both fine-grained and coarse-grained parallel programming in either a MIMD or SPMD style, interoperate with existing MPI libraries, and use existing hardware. The PRAM C model can also be integrated easily with existing models. Unlike related efforts proposing innovative hardware with the goal to realize the PRAM, ours can be a pure software solution with the purpose to provide a practical programming environment for existing parallel machines; it also has the potential to perform well on future parallel architectures.

  20. Fine grained recognition of masonry walls for built heritage assessment

    NASA Astrophysics Data System (ADS)

    Oses, N.; Dornaika, F.; Moujahid, A.

    2015-01-01

    This paper presents the ground work carried out to achieve automatic fine grained recognition of stone masonry. This is a necessary first step in the development of the analysis tool. The built heritage that will be assessed consists of stone masonry constructions and many of the features analysed can be characterized according to the geometry and arrangement of the stones. Much of the assessment is carried out through visual inspection. Thus, we apply image processing on digital images of the elements under inspection. The main contribution of the paper is the performance evaluation of the automatic categorization of masonry walls from a set of extracted straight line segments. The element chosen to perform this evaluation is the stone arrangement of masonry walls. The validity of the proposed framework is assessed on real images of masonry walls using machine learning paradigms. These include classifiers as well as automatic feature selection.

  1. Fine grain separation for the production of biomass fuel from mixed municipal solid waste.

    PubMed

    Giani, H; Borchers, B; Kaufeld, S; Feil, A; Pretz, T

    2016-01-01

    The main goal of the project MARSS (Material Advanced Sustainable Systems) is to build a demonstration plant in order to recover a renewable biomass fuel suitable for the use in biomass power plants out of mixed municipal solid waste (MMSW). The demonstration plant was constructed in Mertesdorf (Germany), working alongside an existing mechanical-biological treatment plant, where the MMSW is biological dried under aerobe conditions in rotting boxes. The focus of the presented sorting campaign was set on the processing of fine grain particles minor than 11.5mm which have the highest mass content and biogenic energy potential of the utilized grain size fractions. The objective was to produce a biomass fuel with a high calorific value and a low content of fossil (plastic, synthetic) materials while maximizing the mass recovery. Therefore, the biogenic components of the dried MMSW are separated from inert and fossil components through various classification and sifting processes. In three experimental process setups of different processing depths, the grain size fraction 4-11.5mm was sifted by the use of air sifters and air tables.

  2. Characterisation of Fine Ash Fractions from the AD 1314 Kaharoa Eruption

    NASA Astrophysics Data System (ADS)

    Weaver, S. J.; Rust, A.; Carey, R. J.; Houghton, B. F.

    2012-12-01

    The AD 1314±12 yr Kaharoa eruption of Tarawera volcano, New Zealand, produced deposits exhibiting both plinian and subplinian characteristics (Nairn et al., 2001; 2004, Leonard et al., 2002, Hogg et al., 2003). Their widespread dispersal yielded volumes, column heights, and mass discharge rates of plinian magnitude and intensity (Sahetapy-Engel, 2002); however, vertical shifts in grain size suggest waxing and waning within single phases and time-breaks on the order of hours between phases. These grain size shifts were quantified using sieve, laser diffraction, and image analysis of the fine ash fractions (<1 mm in diameter) of some of the most explosive phases of the eruption. These analyses served two purposes: 1) to characterise the change in eruption intensity over time, and 2) to compare the three methods of grain size analysis. Additional analyses of the proportions of components and particle shape were also conducted to aid in the interpretation of the eruption and transport dynamics. 110 samples from a single location about 6 km from source were sieved at half phi intervals between -4φ to 4φ (16 mm - 63 μm). A single sample was then chosen to test the range of grain sizes to run through the Mastersizer 2000. Three aliquots were tested; the first consisted of each sieve size fraction ranging between 0φ (1000 μm) and <4φ (<63 μm, i.e. the pan). For example, 0, 0.5, 1, …, 4φ, and the pan were ran through the Mastersizer and then their results, weighted according to their sieve weight percents, were summed together to produce a total distribution. The second aliquot included 3 samples ranging between 0-2φ (1000-250 μm), 2.5-4φ (249-63 μm), and the pan. A single sample consisting of the total range of grain sizes between 0φ and the pan was used for the final aliquot. Their results were compared and it was determined that the single sample consisting of the broadest range of grain sizes yielded an accurate grain size distribution. This data was

  3. Fine-Grained Access Control for Electronic Health Record Systems

    NASA Astrophysics Data System (ADS)

    Hue, Pham Thi Bach; Wohlgemuth, Sven; Echizen, Isao; Thuy, Dong Thi Bich; Thuc, Nguyen Dinh

    There needs to be a strategy for securing the privacy of patients when exchanging health records between various entities over the Internet. Despite the fact that health care providers such as Google Health and Microsoft Corp.'s Health Vault comply with the U.S Health Insurance Portability and Accountability Act (HIPAA), the privacy of patients is still at risk. Several encryption schemes and access control mechanisms have been suggested to protect the disclosure of a patient's health record especially from unauthorized entities. However, by implementing these approaches, data owners are not capable of controlling and protecting the disclosure of the individual sensitive attributes of their health records. This raises the need to adopt a secure mechanism to protect personal information against unauthorized disclosure. Therefore, we propose a new Fine-grained Access Control (FGAC) mechanism that is based on subkeys, which would allow a data owner to further control the access to his data at the column-level. We also propose a new mechanism to efficiently reduce the number of keys maintained by a data owner in cases when the users have different access privileges to different columns of the data being shared.

  4. Superplastic forming characteristics of fine-grained 5083 aluminum

    NASA Astrophysics Data System (ADS)

    Verma, R.; Friedman, P. A.; Ghosh, A. K.; Kim, C.; Kim, S.

    1995-10-01

    Superplastic forming characteristics of a fine-grained 5083 aluminum sheet have been investigated by means of gas-pressure forming of a rectangular pan. This part geometry lends itself to a simple representation in terms of nearly one-dimensional sheet stretching and permits reasonably rigorous control of strain rate throughout the forming cycle. This study followed a study of the uniaxial tensile properties carried out on this alloy. A two-stage forming cycle, which comprised a short, rapid prestraining stage followed by a stage of slower rate of superplastic straining, was used because the uniaxial tensile work showed enhancement of superplastic response of this alloy under this condition. The study examined the effect of process parameters such as initial gas pressurization rate, level of hydrostatic pressure, and lubricants on the thinning characteristics of the sheet, especially along the die entry radii. The gas pressure/time cycle was suitably modified to avoid premature sheet failure due to excessive sheet thinning or cavitation. Cavitation under the biaxial forming condition and the effect of hydrostatic pressure on cavitation suppression were evaluated. A defect-free pan with sharp corners was formed.

  5. Electro-Osmotic Remediation of Fine-Grained Sediments

    SciTech Connect

    Cherepy, N.J.; McNab, W.W.; Wildenschild, D.; Ruiz, R.; Elsholz, A.

    1999-11-22

    The coupled-flow phenomenon, electro-osmosis, whereby water flow results from an applied electrical potential gradient, is being used at Lawrence Livermore National Laboratory to induce water flow through deep (25-40 meters below surface) fine-grained sediments. The scoping work described here lays the groundwork for implementation of this technology to remediate solvent-contaminated clayey zones at the LLNL site. The electro-osmotic conductivity (k{sub e}) measured in-situ between two 37 m deep wells, 3 m apart of 2.3 x 10{sup -9} m{sup 2}/s-V is in good agreement with the value determined from bench-top studies on the core extracted from one of the wells of 0.94 {+-} 0.29 x 10{sup -9} m{sup 2}/s-V. Hydraulic conductivity (k{sub h}) of the same core is measured to be 2.03 {+-} 0.36 x 10{sup -10} m/s. Thus, a voltage gradient of 1 V/cm produces an effective hydraulic conductivity of {approx}1 x 10{sup -7} m/s; an increase in conductivity of nearly three orders of magnitude.

  6. Recombination of hydrogen atoms on fine-grain graphite

    NASA Astrophysics Data System (ADS)

    Drenik, Aleksander; Vesel, Alenka; Kreter, Arkadi; Mozetič, Miran

    2011-04-01

    The probability of recombination of hydrogen atoms on surfaces of fine-grain graphite EK98 was investigated as a function of surface roughness. The source of hydrogen atoms used in this experiment was weakly ionised plasma created with an inductively coupled radiofrequency generator at pressures from 30 Pa to 175 Pa in hydrogen. Hydrogen atom density was measured by means of fibre optic catalytic probes. The recombination coefficient of the graphite samples was determined by observing their impact on the spatial distribution of the atom density in a closed side-arm of the reactor. Smith's diffusion model was used to calculate the values of the recombination coefficient. The measured recombination coefficient was found to increase much faster than the measured effective surface. This discrepancy is explained by the fact that on a surface which is not perfectly flat, there is a finite probability for multiple collisions. Impinging atoms collide more than once with the surface before they are reflected into the surface, which results in a larger probability of recombination.

  7. Benzene and MTBE Sorption in Fine Grain Sediments

    NASA Astrophysics Data System (ADS)

    Leal-Bautista, R. M.; Lenczewski, M. E.

    2003-12-01

    The practice of adding methyl tert-butyl ether (MTBE) to gasoline started in the late 1970s and increased dramatically in the 1990s. MTBE first was added as a substitute for tetra-ethyl lead then later as a fuel oxygenate. Although the use of MTBE has resulted in significant reduction in air pollution, it has become a significant groundwater contaminant due to its high solubility in water, high environmental mobility, and low potential for biodegradation. A recent report (1999-2001) by the Metropolitan Water District of Southern California in collaboration with United State Geological Survey and the Oregon Health and Science University found that MTBE was the second most frequent detected volatile organic compound in groundwater. In Illinois, MTBE has been found in 26 of the 1,800 public water supplies. MTBE has also been blended in Mexico into two types of gasoline sold in the country by the state oil company (PEMEX) but is not monitored in groundwater at this time. Early research on MTBE considered it unable to adsorb to soils and sediments, however, by increasing the organic matter and decreasing the size of the grains (silts or clays) this may increase sorption. The objective of this study is to determine if fine grained materials have the potential for sorption of MTBE due to its high specific surface area (10-700 m 2/g) and potentially high organic matter (0.5-3.8%). The experiment consisted of sorption isotherms to glacial tills from DeKalb, Illinois and lacustrine clays from Chalco, Mexico. Experiments were performed with various concentrations of MTBE and benzene (10, 50, 100, 500 and 1000 ug/L) at 10° C and 25° C. Results showed a range of values for the distribution coefficient (Kd, linear model). At 10° C the Kd value for MTBE was 0.187 mL/g for lacustrine clay while the glacial loess had a value of 0.009 mL/g. The highest Kd values with MTBE were 0.2859 mL/g for organic rich lacustrine clays and 0.014 mL/g for glacial loess at 25° C. The highest

  8. Advanced SEM-EDX and Isotope Mapping of a Refractory Grain in a Fine-Grained IDP

    NASA Astrophysics Data System (ADS)

    Starkey, N. A.; Franchi, I. A.; Salge, T.; Brearley, A. J.

    2015-07-01

    We present high spatial resolution SEM-EDX and O isotope mapping to reveal the presence of a melilite-olivine refractory grain in a fine-grained IDP. We use this to discuss transport of material from the inner solar system and formation of comets.

  9. A unique, (almost) unaltered spinel-rich fine-grained inclusion in Kainsaz

    NASA Technical Reports Server (NTRS)

    Holmberg, B. B.; Hashimoto, A.

    1992-01-01

    A unique, spinel-rich, extremely porous fine-grained inclusion in the Kainsaz (CO3) meteorite is reported. This inclusion is the least altered fine-grained inclusion yet discovered, having escaped almost entirely the secondary alterations experienced by Allende fine-grained inclusions. The inclusion is comprised of loosely packed 5-30 microns spinel grains mantled by thin layers of melilite, anorthite, and diopsidic pyroxene. The inclusion, which has over 30 vol pct void space, is one of the most spinel-rich, most porous fine-grained inclusions seen to date. The mineralogy of the inclusion matches that which has been predicted for a precursor of the altered mineral assemblages of Allende fine-grained inclusions, though a lack of interstitial material in the Kainsaz inclusion reduces the likelihood of a direct genetic relationship between the two (Allende fine-grained inclusions contain abundant interstitial material). Its mineralogical composition confirms that the precursors of other, more altered, fine-grained inclusions were assemblages of refractory minerals exclusively.

  10. Provenance of KREEP and the exotic component - Elemental and isotopic studies of grain size fractions in lunar soils

    NASA Technical Reports Server (NTRS)

    Evensen, N. M.; Murthy, V. R.; Coscio, M. R., Jr.

    1974-01-01

    Sieve fraction analyses of lunar soils reveal the presence of a fine-grained exotic component enriched in K, Rb, Sr, Ba, and in radiogenic Sr in all soils. The probable source of this exotic component is the areas of high-surficial radioactivity observed by orbital gamma ray spectrometry, such as those at Fra Mauro and Archimedes. If the exotic component is fine-grained KREEP, the origin and distribution of KREEP fragments in the soils are identified. It is suggested that the exotic component represents trace element enriched material located at some depth in the Imbrium area which was surficially deposited during Imbrium excavation.

  11. Study of a Fine Grained Threaded Framework Design

    NASA Astrophysics Data System (ADS)

    Jones, C. D.

    2012-12-01

    Traditionally, HEP experiments exploit the multiple cores in a CPU by having each core process one event. However, future PC designs are expected to use CPUs which double the number of processing cores at the same rate as the cost of memory falls by a factor of two. This effectively means the amount of memory per processing core will remain constant. This is a major challenge for LHC processing frameworks since the LHC is expected to deliver more complex events (e.g. greater pileup events) in the coming years while the LHC experiment's frameworks are already memory constrained. Therefore in the not so distant future we may need to be able to efficiently use multiple cores to process one event. In this presentation we will discuss a design for an HEP processing framework which can allow very fine grained parallelization within one event as well as supporting processing multiple events simultaneously while minimizing the memory footprint of the job. The design is built around the libdispatch framework created by Apple Inc. (a port for Linux is available) whose central concept is the use of task queues. This design also accommodates the reality that not all code will be thread safe and therefore allows one to easily mark modules or sub parts of modules as being thread unsafe. In addition, the design efficiently handles the requirement that events in one run must all be processed before starting to process events from a different run. After explaining the design we will provide measurements from simulating different processing scenarios where the processing times used for the simulation are drawn from processing times measured from actual CMS event processing.

  12. Geochemistry of Fine-grained Sediments and Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Sageman, B. B.; Lyons, T. W.

    2003-12-01

    paleosalinity). Authors of a single chapter can hope, at best, to present a cursory glance at the many biogeochemical proxies currently used and under development in sedimentary studies. Our goal, instead, is to focus on a selected suite of tools of particular value in the reconstruction of paleo-environments preserved in fine-grained siliciclastic sedimentary rocks.Fine-grained, mixed siliciclastic-biogenic sedimentary facies - commonly termed hemipelagic (mainly calcareous or siliceous mudrocks containing preserved organic matter (OM)) - are ideal for unraveling the geological past and are thus the focus of this chapter. These strata accumulate in predominantly low-energy basinal environments where the magnitude (and frequency) of lacunae is diminished, resulting in relatively continuous, though generally condensed sequences. Fortunately, condensation tends to benefit geochemical analysis as it helps to amplify some subtle environmental signals. Because hemipelagic facies include contributions from both terrigenous detrital and pelagic biogenic systems, as well as from authigenic components reflecting the burial environment (Figure 1), they are rich archives of geochemical information. In this chapter we present a conceptual model linking the major processes of detrital, biogenic, and authigenic accumulation in fine-grained hemipelagic settings. This model is intended to be a fresh synthesis of decades of prior research on the geochemistry of modern and ancient mudrocks, including our own work.

  13. Creep of partially molten fine-grained gabbro under dry conditions

    NASA Astrophysics Data System (ADS)

    Zhou, Yongsheng; Rybacki, Erik; Wirth, Richard; He, Changrong; Dresen, Georg

    2012-05-01

    Natural fine-grained gabbro was deformed in a Paterson deformation apparatus to evaluate the flow strength of lower crustal rocks containing partial melt. We performed 94 creep stepping tests on seven samples at 300 MPa confining pressure, temperatures between 950°C and 1150°C, and axial stresses of 25-510 MPa, resulting in strain rates between 2.3 × 10-4 and 6.7 × 10-8 s-1. Water content of samples predried at 1000°C at 1 atm was about 0.035 wt % H2O. The drying process induced partial melting of the starting material of ˜1 vol % Si-poor and Fe-rich melt at grain boundaries, which increased further up to ˜2 vol % during creep tests. Creep tests reveal strain rates increasing with duration of the tests related to increasing melt content present in the samples. Microstructural observations of deformed samples show melt in triple junctions and melt films contained in grain boundaries. The observed microstructures indicate that the samples were deformed in the dislocation creep regime. Dislocation walls are present in pyroxene and plagioclase grains. Very fine grained (about 10 μm) pyroxene and olivine were produced by mineral reactions and dynamic recrystallization at temperatures >1000°C. Melt fraction ϕ of creep test samples and annealed samples increases linearly with logarithm of time (log(t)), suggesting that strain rate enhancement by partial melting can be described by an exponential function of melt fraction with an exponent coefficient of 128. After applying a correction for the time-dependent increase of melt content the data were fitted to a power law creep equation, resulting in a stress exponent of n = 4.0 ± 0.3, an activation energy of Q = 644 ± 75 kJ mol-1, and a preexponential factor of A = 1010.3 ± 0.4 MPan s-1 for dry gabbro that contains ˜1 vol % melt. The flow law for gabbro from this study is compared to published flow law parameters of basaltic composition rocks.

  14. Characterization of fine fraction mined from two Finnish landfills.

    PubMed

    Mönkäre, Tiina J; Palmroth, Marja R T; Rintala, Jukka A

    2016-01-01

    A fine fraction (FF) was mined from two Finnish municipal solid waste (MSW) landfills in Kuopio (1- to 10-year-old, referred as new landfill) and Lohja (24- to 40-year-old, referred as old landfill) in order to characterize FF. In Kuopio the FF (<20mm) was on average 45±7% of the content of landfill and in Lohja 58±11%. Sieving showed that 86.5±5.7% of the FF was smaller than 11.2mm and the fraction resembled soil. The total solids (TS) content was 46-82%, being lower in the bottom layers compared to the middle layers. The organic matter content (measured as volatile solids, VS) and the biochemical methane potential (BMP) of FF were lower in the old landfill (VS/TS 12.8±7.1% and BMP 5.8±3.4 m(3)CH4/t TS) than in the new landfill (VS/TS 21.3±4.3% and BMP 14.4±9.9 m(3)CH4/t TS), and both were lower compared with fresh MSW. In the Kuopio landfill materials were also mechanically sieved in the full scale plant in two size fraction <30 mm (VS/TS 31.1% and 32.9 m(3)CH4/t TS) and 30-70 mm (VS/TS 50.8% and BMP 78.5m(3)CH4/t TS). The nitrogen (3.5±2.0 g/kg TS), phosphorus (<1.0-1.5 g/kg TS) and soluble chemical oxygen demand (COD) (2.77±1.77 kg/t TS) contents were low in all samples. Since FF is major fraction of the content of landfill, the characterization of FF is important to find possible methods for using or disposing FF mined from landfills.

  15. An EBSD study of texture development and hybrid deformation mechanisms in fine grained calcite aggregates deformed in direct shear

    NASA Astrophysics Data System (ADS)

    Maeder, X.; Trullenque, G.; Drury, M. R.; de Bresser, J.

    2007-12-01

    rotation, along with the fact that the larger grain fraction shows a slightly stronger LPO than the fine grain fraction, suggest a component of dislocation creep in the coarser grains. We suggest therefore that the GSS regime in the fine grain aggregates may be a transient stage evolving into hybrid deformation (GSI and GSS mechanisms) at high strain. The next steps in this study will be to quantify the contribution of the GSI and GSS mechanisms through the EBSD study and develop a new flow law for the hybrid deformation of the Solnhofen limestone.

  16. Periodic Viscous Shear Heating Instability in Fine-Grained Shear Zones: Mechanism for Intermediate Depth Earthquakes

    NASA Astrophysics Data System (ADS)

    Coon, E.; Kelemen, P.; Hirth, G.; Spiegelman, M.

    2005-12-01

    initial T of 600 to 850 C, this produced periodic viscous shear heating events with periods of 100's to 1000's of years. Strain rates during these events approach 1 per second as temperatures reach 1400. Cooling between events returns the shear zone almost to its initial temperature, though ultimately shear zone temperature between events exceeds 850 C resulting in stable viscous creep. Analysis shows that our system of equations jumps from one steady state to another, depending on a non-dimensional number relating the rate of shear heating to the rate of diffusive cooling. This year, Kelemen and Hirth show that the rate of stress drop during shear heating events is greater than the rate of elastic stress relaxation, so that shear heating events are a runaway instability. Rather than capping the temperature at 1400 C, we parameterize melt fraction as a function of T, and shear viscosity as a function of melt fraction. A problem with our 1D model is that predicted displacements are too large (1 to 20 m) during shear heating events, essentially because there is no resistance at shear zone ends. To address this, Coon and Spiegelman have embarked on a 3D model, incorporating a pre-existing fine-grained, tabular shear zone of finite extent, with a visco-elastic rheology for both shear zone and wall rocks. Preliminary 1D models using this approach show that the more complicated rheology yields the same result as the simpler model. We will present preliminary results, and determine the Maxwell time for this problem, since low strain rates could produce viscous relaxation in both shear zone and wall rocks with negligible shear heating.

  17. Fine grained event processing on HPCs with the ATLAS Yoda system

    NASA Astrophysics Data System (ADS)

    Calafiura, Paolo; De, Kaushik; Guan, Wen; Maeno, Tadashi; Nilsson, Paul; Oleynik, Danila; Panitkin, Sergey; Tsulaia, Vakhtang; Van Gemmeren, Peter; Wenaus, Torre

    2015-12-01

    High performance computing facilities present unique challenges and opportunities for HEP event processing. The massive scale of many HPC systems means that fractionally small utilization can yield large returns in processing throughput. Parallel applications which can dynamically and efficiently fill any scheduling opportunities the resource presents benefit both the facility (maximal utilization) and the (compute-limited) science. The ATLAS Yoda system provides this capability to HEP-like event processing applications by implementing event-level processing in an MPI-based master-client model that integrates seamlessly with the more broadly scoped ATLAS Event Service. Fine grained, event level work assignments are intelligently dispatched to parallel workers to sustain full utilization on all cores, with outputs streamed off to destination object stores in near real time with similarly fine granularity, such that processing can proceed until termination with full utilization. The system offers the efficiency and scheduling flexibility of preemption without requiring the application actually support or employ check-pointing. We will present the new Yoda system, its motivations, architecture, implementation, and applications in ATLAS data processing at several US HPC centers.

  18. The protein fraction from wheat-based dried distiller's grain with solubles (DDGS): extraction and valorization

    PubMed Central

    Villegas-Torres, M.F.; Ward, J.M.; Lye, G.J.

    2015-01-01

    Nowadays there is worldwide interest in developing a sustainable economy where biobased chemicals are the lead actors. Various potential feedstocks are available including glycerol, rapeseed meal and municipal solid waste (MSW). For biorefinery applications the byproduct streams from distilleries and bioethanol plants, such as wheat-based dried distiller's grain with solubles (DDGS), are particularly attractive, as they do not compete for land use. Wheat DDGS is rich in polymeric sugars, proteins and oils, making it ideal as a current animal feed, but also a future substrate for the synthesis of fine and commodity chemicals. This review focuses on the extraction and valorization of the protein fraction of wheat DDGS as this has received comparatively little attention to date. Since wheat DDGS production is expected to increase greatly in the near future, as a consequence of expansion of the bioethanol industry in the UK, strategies to valorize the component fractions of DDGS are urgently needed. PMID:25644639

  19. Chemical weathering trends in fine-grained ephemeral stream sediments of the McMurdo Dry Valleys, Antarctica

    NASA Astrophysics Data System (ADS)

    Marra, Kristen R.; Elwood Madden, Megan E.; Soreghan, Gerilyn S.; Hall, Brenda L.

    2017-03-01

    We investigated chemical weathering trends within the fine-grained (< 63 μm; silt and clay) fraction of sediments collected from meltwater streams emanating from glaciers in the McMurdo Dry Valleys (MDV; Wright and Taylor Valleys) by integrating grain size, BET surface area, and whole-rock geochemistry. While both valleys currently host cold-based glaciers, the sediment underlying the ephemeral glacial streams was deposited under differing glacial conditions. In Wright Valley (Clark Glacier stream), Brownworth and Trilogy drifts were deposited via cold-based glaciation, whereas the Ross Sea drift that underlies Delta Stream in Taylor Valley likely reflects contributions from wet-based ice. Wright Valley stream sediments are typically coarser grained and have a higher silt content as compared to Taylor Valley sediments. These sediments consist primarily of pyroxenes, quartz, and feldspars, with the percentages of pyroxenes and quartz systematically increasing downstream. The percentage of phyllosilicates ranges from 4 to 18% and decreases with downstream distance. In contrast, Taylor Valley sediments (Delta Stream) are finer-grained and exhibit lower percentages of both pyroxene and quartz and a significantly higher percentage of phyllosilicates (30-43%). Concentrations of all mineral phases remain relatively consistent in abundance with downstream transport in the Delta Stream transect as compared to Clark Glacier stream sediments. Standard chemical weathering indices, such as the Chemical Index of Alteration (CIA), indicate that chemical weathering is occurring within the silt and clay fractions of Antarctic stream sediments and is particularly pronounced in Delta Stream sediments that have BET surface area measurements > 40 m2/g. Utilization of MFW (mafic-felsic-weathered) and A-CN-K (Al2O3-CaO + Na2O-K2O) plots, however, are more effective in discerning the extent and nature of chemical weathering in these stream systems. Ca and Na depletion observed within the

  20. Space Weathering in the Fine Size Fractions of Lunar Soils: Soil Maturity Effects

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Wentworth, S. J.; McKay, D. S.; Taylor, L. A.; Pieters, C.; Morris, R. V.

    1999-01-01

    The effects of space weathering on the optical properties of lunar materials have been well documented. These effects include a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. However, the regolith processes that cause these effects are not well known, nor is the petrographic setting of the products of these processes fully understood. A Lunar Soil Characterization Consortium has been formed with the purpose of systematically integrating chemical and mineralogical data with the optical properties of lunar soils. Understanding space-weathering effects is critical in order to fully integrate the lunar sample collection with remotely-sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, and Galileo) We have shown that depositional processes (condensation of impact-derived vapors, sputter deposits, accreted impact material, e.g., splash glass, spherules, etc.) are a major factor in the modification of the optical surfaces of lunar regolith materials. In mature soils, it is the size and distribution of the nanophase metal in the soil grains that has the major effect on optical properties. In this report, we compare and contrast the space-weathering effects in an immature and a mature soil with similar elemental compositions. For this study, we analyzed <10 micron sieve fractions of two Apollo 17 soils, 79221 (mature, Is/FeO = 81) and 71061 (immature, Is/FeO = 14). Details of the sieving procedures and allocation scheme are given else where. The results of other detailed chemical, mineralogical, and spectroscopic analyses of these soil samples are reported elsewhere. A representative sample of each soil was embedded in low-viscosity epoxy, and thin sections (about 70nm thick) were obtained through ultra microtomy. The thin sections used for these analyses typically contained cross sections of up to 500 individual

  1. Friction stir weld tools having fine grain structure

    DOEpatents

    Grant, Glenn J.; Frye, John G.; Kim, Jin Yong; Lavender, Curt A.; Weil, Kenneth Scott

    2016-03-15

    Tools for friction stir welding can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes by utilizing improved compositions and processes of fabrication. Furthermore, the tools resulting from the improved compositions and processes of fabrication can exhibit better distribution and homogeneity of chemical constituents, greater strength, and/or increased durability. In one example, a friction stir weld tool includes tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter.

  2. A TEM Investigation of the Fine-Grained Matrix of the Martian Basaltic Breccia NWA 7034

    NASA Technical Reports Server (NTRS)

    Muttik, N.; Keller, L. P.; Agee, C. B.; McCubbin, F. M.; Santos, A. R.; Rahman, Z.

    2014-01-01

    The martian basaltic breccia NWA 7034 is characterized by fine-grained groundmass containing several different types of mineral grains and lithologic clasts. The matrix composition closely resembles Martian crustal rock and soil composition measured by recent rover and orbiter missions. The first results of NWA 7034 suggest that the brecciation of this martian meteorite may have formed due to eruptive volcanic processes; however, impact related brecciation processes have been proposed for paired meteorites NWA 7533 and NWA 7475]. Due to the very fine grain size of matrix, its textural details are difficult to resolve by optical and microprobe observations. In order to examine the potential nature of brecciation, transmission electron microscopy (TEM) studies combined with focused ion-beam technique (FIB) has been undertaken. Here we present the preliminary observations of fine-grained groundmass of NWA 7034 from different matrix areas by describing its textural and mineralogical variations and micro-structural characteristics.

  3. Mineralogy of fine-grained material in the Krymka (LL3.1) chondrite

    NASA Astrophysics Data System (ADS)

    Semenenko, V. P.; Bischoff, A.; Weber, I.; Perron, C.; Girich, A. L.

    2001-08-01

    Two dark lithic fragments and matrix of the Krymka LL3.1 chondrite were mineralogically and chemically studied in detail. These objects are characterised by the following chemical and mineralogical characteristics, which distinguish them from the host chondrite Krymka: (1) bulk chemical analyses revealed low totals (systematically lower than 94 wt%) due to high porosity; (2) enrichment in FeO and depletion in S, MgO and SiO2 due to a high abundance of Fe-rich silicates and low sulfide abundance; (3) fine-grained, almost chondrule-free texture with predominance of a porous, cryptocrystalline groundmass and fine grains; (4) occurrence of a small amount of once-molten material (microchondrules) enclosed in fine-grained materials; (5) occurrence of accretionary features, especially unique accretionary spherules; (6) high abundance of small calcium- aluminium-rich inclusions (CAIs) in one of the fine-grained fragments. It is suggested that the abundance of CAIs in this fragment is one of the highest ever found in an ordinary chondrite. Accretionary, fine-grained spherules within one of the fragments bear fundamental information about the initial stages of accretion as well as on the evolution of the clast, its incorporation, and history within the bulk rock of Krymka. The differences in porosity, bulk composition, and mineralogy of cores and rims of the fine-grained spherulitic objects allow us to speculate on the following processes: (1) Low velocity accretion of tiny silicate grains onto the surface of coarse metal or silicate grains in a dusty region of the nebula is the beginning of the formation of accretionary, porous (fluffy) silicate spherules. (2) Within a dusty environment with decreasing silicate/(metal + sulfide) ratio the porous spherules collected abundant metal and sulfide particles together with silicate dust, which formed an accretionary rim. Variations of the silicate/(sulfide + metal) ratio in the dusty nebular environment result in the formation of

  4. Dry fractionation creates fractions of wheat distillers dried grains and solubles with highly digestible nutrient content for grower pigs.

    PubMed

    Yáñez, J L; Beltranena, E; Zijlstra, R T

    2014-08-01

    Nutrient digestibility in distillers dried grains with solubles (DDGS) is limited by constraints such as particle size and fiber. Wheat DDGS contains more fiber than corn DDGS that may reduce its nutritional value in swine feeds. Dry fractionation may create DDGS fractions with low and high fiber content; therefore, wheat DDGS was processed sequentially using a vibratory sifter and gravity table. Sufficient material was obtained from 3 wheat DDGS fractions that differed in particle size from fine to coarse (Fraction A [FA], Fraction C [FC], and Fraction D [FD]). Five cornstarch-based diets were mixed that contained either 40% wheat DDGS, 30% FA, 30% FC plus 10% soybean meal (SBM), 30% FD plus 15% SBM, or 35% SBM. A sixth, N-free diet served to subtract basal endogenous AA losses and as control for energy digestibility calculations. Six ileal-cannulated barrows (29 kg BW) were fed 6 diets at 2.8 times maintenance for DE in six 9-d periods as a 6 × 6 Latin square. Feces and ileal digesta were collected sequentially for 2 d each. Wheat DDGS FA, FC, and FD were 258, 530, and 723 μm in mean particle size and contained 44.8, 39.3, and 33.8% CP and 29.1, 35.1, and 37.5% in NDF, respectively. The apparent total tract digestibility (ATTD) of GE was greater (P < 0.05) for SBM than wheat DDGS, was greater (P < 0.05) for FA than wheat DDGS, and did not differ between FC, FD, and wheat DDGS. The standardized ileal digestibility (SID) did not differ between SBM and wheat DDGS (P > 0.05) for most AA. The SID of Arg, Lys, Trp, and available Lys was greater (P < 0.05) for FD than wheat DDGS but was similar for FA, FC, and wheat DDGS and was greater (P < 0.05) for FD than SBM. The DE and NE value was greater (P < 0.05) for SBM, FA, and FC than wheat DDGS and did not differ between FD and wheat DDGS. The SID content of indispensable AA and available Lys was greater (P < 0.05) for SBM than wheat DDGS. The SID content of Ile, Leu, Met, Phe, and Val was greater (P < 0.05) for FA than

  5. Liquefaction Susceptibility of Fine-Grained Soils Preliminary Study Report

    DTIC Science & Technology

    1987-09-01

    while the ground to its south, peneplain and coastal plain areas, con- tinues to subside. Because of this heave-subside process, the Ruan river has been...10 percent of minus 0.074 mn particles, as shown in Figure 25. Mean grain sizes of lique- fied soils from Tangshan and its vicinity ( peneplain ), the...particles increases from the peneplain and inclined plain to the coastal plain. Some statistics on soils liquefied during the Tangshan earthquake are

  6. I/O Router Placement and Fine-Grained Routing on Titan to Support Spider II

    SciTech Connect

    Ezell, Matthew A; Dillow, David; Oral, H Sarp; Wang, Feiyi; Tiwari, Devesh; Maxwell, Don E; Leverman, Dustin B; Hill, Jason J

    2014-01-01

    The Oak Ridge Leadership Computing Facility (OLCF) introduced the concept of Fine-Grained Routing in 2008 to improve I/O performance between the Jaguar supercomputer and Spider, OLCF s center-wide Lustre file system. Fine-grained routing organizes I/O paths to minimize congestion. Jaguar has since been upgraded to Titan, providing more than a ten-fold improvement in peak performance. To support the center s increased computational capacity and I/O demand, the Spider file system has been replaced with Spider II. Building on the lessons learned from Spider, an improved method for placing LNET routers was developed and implemented for Spider II. The fine-grained routing scripts and configuration have been updated to provide additional optimizations and better match the system setup. This paper presents a brief history of fine-grained routing at OLCF, an introduction to the architectures of Titan and Spider II, methods for placing routers in Titan, and details about the fine-grained routing configuration.

  7. [Protein fraction distribution in milling and screened physical fractions of grain amaranth].

    PubMed

    Búcaro Segura, María Ester; Bressani, Ricardo

    2002-06-01

    The purpose of the study was to establish the protein distribution based on solubility in physical fractions of amaranth flour, in particular between the flour from the germ and that from the perisperm. The protein distribution was obtained applying a series of solvents sequentially utilized in the classical methodology of Osborne & Mendel. The sample of A. cruentus weighing 2000 g was divided into 4 subsamples of 500 g each. One was left as the control while the other 3 were ground individually with a mill. Each flour was screened through 18, 20, 30 and 40 mesh screens, so that 5 fractions were obtained from each of the whole grain flours. Samples of each screened fractions were observed by stereoscopy and analyzed for moisture, fat and protein. This characterization suggested that the fraction above the 30 mesh screen and the flour which passed the 40 mesh screen probably were the perisperm and germ respectively. The 30 mesh sample contained 2.34 fat and 9.05% protein while the 40 mesh contained 16.18% fat and 26.46% protein. The extraction and partitioning of the proteins indicated that the most important fractions in germ and perisperm were the water soluble and glutelins measured by Kjeldahl. The relationship of the water soluble + globulin to glutelins ratio was 2.1 to 1 in the whole grain, 1.9 to 1 in the perisperm and 1.7 to 1 in the germ. The distribution of proteins was very much alike between germ and perisperm. The levels of prolamines were quite low. The protein extraction of the perisperm proteins retained on the 30 mesh screen was low (71.1%) measured by Kjeldahl and 47.4% with the Bradford method to measure protein.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Ice is one of the most abundant materials in our solar system. It is the principal constituent of most of the moons of the outer solar system. Thus, the flow behavior of ice is of great interest when studying geodynamic processes on icy moons. Grain growth is an elementary process that is assumed to be important in the ice sheet layering of planetary moons, where temperatures 100-273 K exist. We concentrate on the questions to what extent grain growth may influence the evolution of strength of deforming ice and if the grain growth process is independent or dependent of deformation. The answers to these questions will help us to quantitatively test the hypothesis that the progressive evolution of the grain (crystal) size distribution of deforming and recrystallizing ice directly affects its rheological behaviour in terms of composite grain-size-sensitive (GSS) and grain-size-insensitive (GSI) creep, and that this might, after time, result in a steady state balance between mechanisms of GSS and GSI creep. We performed static grain growth experiments at different temperatures and a pressure (P) of 1 atm, and deformation experiments at P = 30-100 MPa starting in the GSS-creep field. The starting material ice Ih has a grain size < 2 μm and was generated by a special pressure-release technique described by Stern et al. (1997) resulting in dense ice aggregates. The ice grains of the polycrystalline starting samples were randomly oriented and the material has a porosity of < 0.5%. For the grain growth tests a Hart Scientific temperature bath was filled with d-Limonene as cooling medium. The ice specimens were put into sealed alumina cylinders. For the grain growth tests, temperatures (T) between 213 K and 268 K were chosen. The durations of these tests varied between one day and two weeks. For the deformation experiments, temperatures of > 170 K and strain rates between 10-8 s-1 and 10-4 s-1 were chosen. Grain sizes, grain size distributions and grain topologies were

  9. Process for preparing fine grain silicon carbide powder

    DOEpatents

    Wei, G.C.

    Finely divided silicon carbide powder is obtained by mixing colloidal silica and unreacted phenolic resin in either acetone or methanol, evaporating solvent from the obtained solution to form a gel, drying and calcining the gel to polymerize the phenolic resin therein, pyrolyzing the dried and calcined gel at a temperature in the range of 500 to 1000/sup 0/C, and reacting silicon and carbon in the pyrolyzed gel at a temperature in the range of 1550 to 1700/sup 0/C to form the powder.

  10. Process for preparing fine grain titanium carbide powder

    DOEpatents

    Janney, M.A.

    1985-03-12

    A method for preparing finely divided titanium carbide powder in which an organotitanate is reacted with a carbon precursor polymer to provide an admixture of the titanium and the polymer at a molecular level due to a crosslinking reaction between the organotitanate and the polymer. The resulting gel is dried, pyrolyzed to drive off volatile components and provide carbon. The resulting solids are then heated at an elevated temperature to convert the titanium and carbon to high-purity titanium carbide powder in a submicron size range.

  11. Process for preparing fine grain titanium carbide powder

    DOEpatents

    Janey, Mark A.

    1986-01-01

    A method for preparing finely divided titanium carbide powder in which an organotitanate is reacted with a carbon precursor polymer to provide an admixture of the titanium and the polymer at a molecular-level due to a crosslinking reaction between the organotitanate and the polymer. The resulting gel is dried, pyrolyzed to drive off volatile components and provide carbon. The resulting solids are then heated at an elevated temperature to convert the titanium and carbon to high-purity titanium carbide powder in a submicron size range.

  12. An Action-Based Fine-Grained Access Control Mechanism for Structured Documents and Its Application

    PubMed Central

    Su, Mang; Li, Fenghua; Tang, Zhi; Yu, Yinyan; Zhou, Bo

    2014-01-01

    This paper presents an action-based fine-grained access control mechanism for structured documents. Firstly, we define a describing model for structured documents and analyze the application scenarios. The describing model could support the permission management on chapters, pages, sections, words, and pictures of structured documents. Secondly, based on the action-based access control (ABAC) model, we propose a fine-grained control protocol for structured documents by introducing temporal state and environmental state. The protocol covering different stages from document creation, to permission specification and usage control are given by using the Z-notation. Finally, we give the implementation of our mechanism and make the comparisons between the existing methods and our mechanism. The result shows that our mechanism could provide the better solution of fine-grained access control for structured documents in complicated networks. Moreover, it is more flexible and practical. PMID:25136651

  13. Structural evolution and the Hall-Petch relationship in an Al-Mg-Li-Zr alloy with ultra-fine grain size

    SciTech Connect

    Furukawa, Minoru; Iwahashi, Yoshinori; Horita, Zenji; Nemoto, Minoru; Tsenev, N.K.; Valiev, R.Z.; Langdon, T.G.

    1997-11-01

    Experiments were conducted on an Al-5.5% Mg-2.2% Li-0.12% Zr alloy to investigate the feasibility of introducing an ultra-fine grain size using equal-channel angular (ECA) pressing and of retaining an ultra-fine grain size at elevated temperatures. It is shown that ECA pressing is capable of reducing the grain size from an initial value of {approximately}400 {micro}m to a value of {approximately}1.2 {micro}m. However, the microstructure after ECA pressing is heterogeneous, with many areas of equiaxed grains having high angle grain boundaries and some regions of subgrains with boundaries having low angles of misorientation. Unlike earlier experiments on Al-Mg binary alloys, it is demonstrated that the grain size of the Al-Mg-Li-Zr alloy is reasonably stable up to temperatures as high as {approximately}700 K because of the presence in the matrix of a fine dispersion of {beta}{prime}-Al{sub 3}Zr precipitates. Microhardness data confirm the Hall-Petch relationship for grain sizes above {approximately}2 {micro}m produced by annealing at temperatures above {approximately}673 K, but the Hall-Petch relationship breaks down at smaller grain sizes because of variations in the volume fraction of the {delta}{prime}-Al{sub 3}Li precipitates.

  14. Pre-fermentation fining effects on the aroma chemistry of Marlborough Sauvignon blanc press fractions.

    PubMed

    Parish, Katie J; Herbst-Johnstone, Mandy; Bouda, Flo; Klaere, Steffen; Fedrizzi, Bruno

    2016-10-01

    In the wine industry, fining agents are commonly used with many choices now commercially available. Here the influence of pre-fermentation fining on wine aroma chemistry has been explored. Free run and press fraction Sauvignon blanc juices from two vineyards were fined using gelatin, activated carbon, polyvinylpolypyrrolidone (PVPP) and a combination agent which included bentonite, PVPP and isinglass. Over thirty aroma compounds were quantified in the experimental wines. Results showed that activated carbon fining led to a significant (p<0.05) concentration decrease of hexan-1-ol and linalool in the experimental wines when compared to a control, consistent across all vineyard and fraction combinations. Other aroma compounds were also influenced by fining agent, even if vineyards and press fractions played a crucial role. This study confirmed that fining agents used pre-fermentation can influence wine aroma profiles and therefore needs specific tailoring addressing style and origin of grape.

  15. Fine-grain authorization policies in the GRID : design and implementation.

    SciTech Connect

    Keahey, K.; Welch, V.; Lang, S.; Liu, B.; Meder, S.; Mathematics and Computer Science; Univ. of Chicago; Univ. of Houston

    2004-04-25

    In this paper, we describe our work on enabling fine-grained authorization for resource usage and management. We address the need of virtual organizations to enforce their own polices in addition to those of the resource owners, with regards to both resource consumption and job management. To implement this design, we propose changes and extensions to the Globus Toolkit's version 2 resource management mechanism. We describe the prototype and policy language that we have designed to express fine-grained policies and present an analysis of our solution.

  16. Fine-grained authorization for job execution in the Grid : design and implementation.

    SciTech Connect

    Keahey, K.; Welch, V.; Lang, S.; Liu, B.; Meder, S.; Mathematics and Computer Science; Univ. of Chicago; Univ. of Houston

    2004-04-25

    In this paper, we describe our work on enabling fine-grained authorization for resource usage and management. We address the need of virtual organizations to enforce their own polices in addition to those of the resource owners, with regards to both resource consumption and job management. To implement this design, we propose changes and extensions to the Globus Toolkit's version 2 resource management mechanism. We describe the prototype and policy language that we have designed to express fine-grained policies and present an analysis of our solution.

  17. Frontiers in Sedimentary Geology: Microstructure of Fine-Grained Sediments from Mud to Shale

    DTIC Science & Technology

    1990-01-01

    time for reviewing Instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection...compilation of peer- reviewed technical papers, most of which were presented at an international symposium-workshop entitled "The Clay Microstructure of Fine...and sedimentology of fine-grained sediments. Review of the book reveals that new breakthroughs in highly specialized disciplines and the advancement of

  18. Ultra Fine-Grained Metals Prepared by Severe Plastic Deformation: A Positron Annihilation Study

    NASA Astrophysics Data System (ADS)

    Čížek, J.; Procházka, I.; Kužel, R.; Matĕj, Z.; Cherkaska, V.; Cieslar, M.; Smola, B.; Stulíková, I.; Brauer, G.; Anwand, W.; Islamgaliev, R. K.; Kulyasova, O.

    2005-05-01

    Recent investigations of ultra fine-grained metals (Cu, Fe, Ni) performed within a Prague-Rossendorf-Ufa collaboration will be reviewed. The specimens were prepared by severe plastic deformation: the high-pressure torsion and equal channel angular pressing. Positron annihilation spectroscopy was used as the main method including (i) the conventional lifetime and the Doppler broadening measurements with 22Na and (ii) the slow-positron implantation spectroscopy with the Doppler broadening measurement. Other methods were also involved: transmission electron microscopy, X-ray diffraction, and microhardness. First, the mean grain size was determined and defects were identified in the as-deformed materials. Defects concentration and spatial distribution were studied in detail. Dislocations situated in distorted regions along grain boundaries, and a few-vacancy clusters distributed homogeneously inside dislocations-free grains, were observed in the ultra fine-grained Cu, Fe, and Ni. Subsequently, the thermal evolution of the ultra fine-grained structures during isochronal annealing was studied.

  19. High-Temperature Creep of Fine-Grained Anorthite Aggregate

    NASA Astrophysics Data System (ADS)

    Yabe, K.; Koizumi, S.; Hiraga, T.

    2014-12-01

    Rheology of the lower crust has often been compared to the creep properties of polycrystalline anorthite. Samples that have been used in previous studies (Dimanov et al., 1999; Rybacki and Dresen, 2000) were prepared through crystallization of anorthite glass which can remain in the experiment and also contain some impurities such as absorbed water, TiO2, MgO and Fe2O3. In this study, we synthesized genuinely pure polycrystalline anorthite using the technique that does not allow the contamination of water and glass phase. Also, we prepared anorthite aggregates with glass phase and/or a small amount (1wt%) of MgO to investigate the creep properties of pure and impure anorthite aggregates. Pure anorthite powders were prepared through high temperature reaction of highly pure and nano-sized powders of CaCO3, Al2O3 and SiO2 and then they were vacuum sintered (Koizumi et al., 2010). For MgO doping, we added Mg(OH)2powders at the synthesis of anorthite powders. Glass phase was introduced to the samples by sintering above melting temperature and subsequent quenching. Constant load tests under 1 atmosphere were performed at temperatures ranging from 1150 to 1380˚C and stresses of 10 to 120 MPa. We measured Arithmetic mean grain size of specimens by microstructural observations using scanning electron microscopy (SEM) before and after creep tests. Grain sizes of all the specimens were around 1 μm before and after the creep test. Log stress versus log strain rate showed a linear relationship where its slope gave a stress exponent, n of 1, indicating that all the samples were deformed under diffusion creep. Anorthite containing MgO and glass phase were more than two and one orders of magnitude weaker than genuinely pure anorthite aggregates, respectively. Further, our pure aggregate exhibited three orders of magnitude lager strength compared to the "pure" aggregate used in previous studies. These results indicate that a small amount of glass and/or impurities including water

  20. Fine-grained debris flows and extraordinary vertebrate burials in the Late Cretaceous of Madagascar

    NASA Astrophysics Data System (ADS)

    Rogers, Raymond R.

    2005-04-01

    Vertebrate fossils are remarkably abundant and exceptionally well preserved within the Upper Cretaceous Maevarano Formation of northwestern Madagascar. The vast majority of these fossils, including all of the currently known bone beds, are entombed within deposits of fine-grained cohesive debris flows. These deposits are typically massive and are characterized by very poor sorting and a significant montmorillonite-dominated silt-clay (mud) fraction ranging from 17% to 46% by weight. Deposition is attributed to recurrent exceptional rainfall events that prompted erosion and flooded ancient channel belts with sediment-laden flows. These extraordinary burial events shielded vertebrate remains from destructive surface processes and also afforded protection for soft tissues. Taphonomic attributes of associated bone concentrations suggest that debris flows had limited transport potential and generally entombed subaerially exposed bone assemblages. The remarkable and recurrent association of bone beds and debris-flow deposits likely reflects marked seasonality in this Late Cretaceous terrestrial ecosystem, with prolonged dry spells prompting mortality and subsequent rains setting debris flows in motion.

  1. The influence of grain size, grain color, and suspended-sediment concentration on light attenuation: Why fine-grained terrestrial sediment is bad for coral reef ecosystems

    NASA Astrophysics Data System (ADS)

    Storlazzi, Curt D.; Norris, Ben K.; Rosenberger, Kurt J.

    2015-09-01

    Sediment has been shown to be a major stressor to coral reefs globally. Although many researchers have tested the impact of sedimentation on coral reef ecosystems in both the laboratory and the field and some have measured the impact of suspended sediment on the photosynthetic response of corals, there has yet to be a detailed investigation on how properties of the sediment itself can affect light availability for photosynthesis. We show that finer-grained and darker-colored sediment at higher suspended-sediment concentrations attenuates photosynthetically active radiation (PAR) significantly more than coarser, lighter-colored sediment at lower concentrations and provide PAR attenuation coefficients for various grain sizes, colors, and suspended-sediment concentrations that are needed for biophysical modeling. Because finer-grained sediment particles settle more slowly and are more susceptible to resuspension, they remain in the water column longer, thus causing greater net impact by reducing light essential for photosynthesis over a greater duration. This indicates that coral reef monitoring studies investigating sediment impacts should concentrate on measuring fine-grained lateritic and volcanic soils, as opposed to coarser-grained siliceous and carbonate sediment. Similarly, coastal restoration efforts and engineering solutions addressing long-term coral reef ecosystem health should focus on preferentially retaining those fine-grained soils rather than coarse silt and sand particles.

  2. The influence of grain size, grain color, and suspended-sediment concentration on light attenuation: why fine-grained terrestrial sediment is bad for coral reef ecosystems

    USGS Publications Warehouse

    Storlazzi, Curt; Norris, Benjamin; Rosenberger, Kurt

    2015-01-01

    Sediment has been shown to be a major stressor to coral reefs globally. Although many researchers have tested the impact of sedimentation on coral reef ecosystems in both the laboratory and the field and some have measured the impact of suspended sediment on the photosynthetic response of corals, there has yet to be a detailed investigation on how properties of the sediment itself can affect light availability for photosynthesis. We show that finer-grained and darker-colored sediment at higher suspended-sediment concentrations attenuates photosynthetically active radiation (PAR) significantly more than coarser, lighter-colored sediment at lower concentrations and provide PAR attenuation coefficients for various grain sizes, colors, and suspended-sediment concentrations that are needed for biophysical modeling. Because finer-grained sediment particles settle more slowly and are more susceptible to resuspension, they remain in the water column longer, thus causing greater net impact by reducing light essential for photosynthesis over a greater duration. This indicates that coral reef monitoring studies investigating sediment impacts should concentrate on measuring fine-grained lateritic and volcanic soils, as opposed to coarser-grained siliceous and carbonate sediment. Similarly, coastal restoration efforts and engineering solutions addressing long-term coral reef ecosystem health should focus on preferentially retaining those fine-grained soils rather than coarse silt and sand particles.

  3. Homotypic and Heterotypic Continuity of Fine-Grained Temperament during Infancy, Toddlerhood, and Early Childhood

    ERIC Educational Resources Information Center

    Putnam, Samuel P.; Rothbart, Mary K.; Gartstein, Maria A.

    2008-01-01

    Longitudinal continuity was investigated for fine-grained and factor-level aspects of temperament measured with the Infant Behaviour Questionnaire-Revised (IBQ-R), Early Childhood Behaviour Questionnaire (ECBQ), and Children's Behaviour Questionnaire (CBQ). Considerable homotypic continuity was found. Convergent and discriminant validity of the…

  4. Hall Petch Behavior in Ultra-Fine-Grained AISI 301LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Rajasekhara, S.; Ferreira, P. J.; Karjalainen, L. P.; Kyröläinen, A.

    2007-06-01

    An ultra-fine-grained AISI 301LN austenitic stainless steel has been achieved by heavy cold rolling, to induce the formation of martensite, and subsequent annealing at 800 °C, 900 °C, and 1000 °C, from 1 to 100 seconds. The microstructural evolution was analyzed using transmission electron microscopy and the yield strength determined by tension testing. Ultra-fine austenite grains, as small as ˜0.54 μm, were obtained in samples annealed at 800 °C for 1 second. For these samples, tensile tests revealed a very high yield strength of ˜700 MPa, which is twice the typical yield strength of conventional fully annealed AISI 301LN stainless steels. An analysis of the relationship between yield strength and grain size in these submicron-grained stainless steels indicates a classical Hall Petch behavior. Furthermore, when the yield dependence on annealing temperature is considered, the results show that the Hall Petch relation is due to an interplay between fine-grained austenite, solid solution strengthening, precipitate hardening, and strain hardening.

  5. Effect of the hull fraction on the beta-glucan contents of barley and oat grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The hull fraction of barley and oat grains affects the beta-glucan (BG) content in whole grains. To evaluate the impact of the hull fraction on BG content in various genetic backgrounds and growth conditions, BG contents were analyzed in five hulled barley lines, seven hulled oat lines, and one F2 ...

  6. Elevated Temperature Strength of Fine-Grained INCONEL Alloy MA754

    SciTech Connect

    T.C. Totemeier; T.M. Lillo; J.A. Simpson

    2005-09-01

    Elevated temperature tensile and creep-rupture tests were performed on INCONEL alloy MA754 in an as-rolled, fine-grained condition. Tensile tests were performed at 25, 800, 900, and 1000°C; creep-rupture tests were performed at 800, 900, and 1000°C. The elevated temperature strength in the fine-grained condition was approximately 25% of the standard, coarse-grained annealed condition. While good ductility was observed in tensile tests at a nominal strain rate of 1×10-3 sec-1, ductility in creep-rupture tests was very low, with failure elongations less than 5% and no reduction in area. Creep deformation appeared to occur solely by cavity formation and growth.

  7. Generation and emplacement of fine-grained ejecta in planetary impacts

    USGS Publications Warehouse

    Ghent, R.R.; Gupta, V.; Campbell, B.A.; Ferguson, S.A.; Brown, J.C.W.; Fergason, R.L.; Carter, L.M.

    2010-01-01

    We report here on a survey of distal fine-grained ejecta deposits on the Moon, Mars, and Venus. On all three planets, fine-grained ejecta form circular haloes that extend beyond the continuous ejecta and other types of distal deposits such as run-out lobes or ramparts. Using Earth-based radar images, we find that lunar fine-grained ejecta haloes represent meters-thick deposits with abrupt margins, and are depleted in rocks 1cm in diameter. Martian haloes show low nighttime thermal IR temperatures and thermal inertia, indicating the presence of fine particles estimated to range from ???10??m to 10mm. Using the large sample sizes afforded by global datasets for Venus and Mars, and a complete nearside radar map for the Moon, we establish statistically robust scaling relationships between crater radius R and fine-grained ejecta run-out r for all three planets. On the Moon, ???R-0.18 for craters 5-640km in diameter. For Venus, radar-dark haloes are larger than those on the Moon, but scale as ???R-0.49, consistent with ejecta entrainment in Venus' dense atmosphere. On Mars, fine-ejecta haloes are larger than lunar haloes for a given crater size, indicating entrainment of ejecta by the atmosphere or vaporized subsurface volatiles, but scale as R-0.13, similar to the ballistic lunar scaling. Ejecta suspension in vortices generated by passage of the ejecta curtain is predicted to result in ejecta run-out that scales with crater size as R1/2, and the wind speeds so generated may be insufficient to transport particles at the larger end of the calculated range. The observed scaling and morphology of the low-temperature haloes leads us rather to favor winds generated by early-stage vapor plume expansion as the emplacement mechanism for low-temperature halo materials. ?? 2010 Elsevier Inc.

  8. Generation and emplacement of fine-grained ejecta in planetary impacts

    NASA Astrophysics Data System (ADS)

    Ghent, Rebecca R.; Gupta, V.; Campbell, B. A.; Ferguson, S. A.; Brown, J. C. W.; Fergason, R. L.; Carter, L. M.

    2010-10-01

    We report here on a survey of distal fine-grained ejecta deposits on the Moon, Mars, and Venus. On all three planets, fine-grained ejecta form circular haloes that extend beyond the continuous ejecta and other types of distal deposits such as run-out lobes or ramparts. Using Earth-based radar images, we find that lunar fine-grained ejecta haloes represent meters-thick deposits with abrupt margins, and are depleted in rocks ⩾1 cm in diameter. Martian haloes show low nighttime thermal IR temperatures and thermal inertia, indicating the presence of fine particles estimated to range from ˜10 μm to 10 mm. Using the large sample sizes afforded by global datasets for Venus and Mars, and a complete nearside radar map for the Moon, we establish statistically robust scaling relationships between crater radius R and fine-grained ejecta run-out r* for all three planets. On the Moon, r* ˜ R-0.18 for craters 5-640 km in diameter. For Venus, radar-dark haloes are larger than those on the Moon, but scale as r* ˜ R-0.49, consistent with ejecta entrainment in Venus' dense atmosphere. On Mars, fine-ejecta haloes are larger than lunar haloes for a given crater size, indicating entrainment of ejecta by the atmosphere or vaporized subsurface volatiles, but scale as R-0.13, similar to the ballistic lunar scaling. Ejecta suspension in vortices generated by passage of the ejecta curtain is predicted to result in ejecta run-out that scales with crater size as R1/2, and the wind speeds so generated may be insufficient to transport particles at the larger end of the calculated range. The observed scaling and morphology of the low-temperature haloes leads us rather to favor winds generated by early-stage vapor plume expansion as the emplacement mechanism for low-temperature halo materials.

  9. Fabrication of ultra-fine grained aluminium tubes by RTES technique

    SciTech Connect

    Jafarzadeh, H. Abrinia, K.

    2015-04-15

    Recently, repetitive tube expansion and shrinking have been exploited as a means for producing ultra-fine grained and nano-crystalline microstructures for magnesium alloy tubes. This method includes two different half-cycles and was based on pressing a tubular part through an angular channel die with two shear zones. Since the aluminium alloys are the most widely used materials in industries, in this study, repetitive tube expansion and shrinking as a new severe plastic deformation technique was applied to commercially pure aluminium for fabricating ultra-fine grained aluminium tubes for the first time and the ability of this process in significant grain refinement is determined even after single cycle. Transmission electron microscopy and X-ray diffraction were used to evaluate the microstructure of the repetitive tube expansion and shrinking processed materials and the examinations showed ultra-fine grains with the average grain size of 320 nm after one cycle of repetitive tube expansion and shrinking. The yield strength, ultimate tensile strength increased notably by the factor of 2.17 and 1.27 respectively, after one cycle of repetitive tube expansion and shrinking, whereas the elongation to failure as well as the uniform elongation decreased. Furthermore, micro-hardness distribution through the part's section proposed the hardness increasing to ~ 55 HV from the initial value of ~ 28 HV after one cycle of repetitive tube expansion and shrinking. - Highlights: • RTES was introduced for fabricating the UFGed AA1050 tubes for the first time. • Nano-grained AA1050 tube was obtained by RTES process. • Grain size of ~ 320 nm was obtained after two half-cycles of RTES process. • Yield and ultimate strength increased by the factor of 2.17 and 1.27 respectively. • The microhardness increased to ~ 55 HV from the initial value of ~ 28 HV.

  10. A grain-fluid mixture model to characterize the dynamics of active landslides in fine-grained soils

    NASA Astrophysics Data System (ADS)

    Spickermann, Anke; Toussaint, Renaud; Travelletti, Julien; Malet, Jean-Philippe; van Asch, Theo

    2013-04-01

    Dynamic continuum modeling of slow-moving landslides in fine-grained material is generally performed by means of visco-plastic models applying the approach of one-phase material. Shortcomings of this approach are the uncertainty of using physical realistic material parameters and that solid and fluid stresses are not considered separately. The objective of this work is to overcome the problems of the one-phase material approach by adopting the theory of grain-fluid mixture. Applying a two-phase model approach enables to distinguish explicitly between 25 e.g. solid friction stress, fluid shear stress (viscous stress), buoyancy and momentum exchange between solid and fluid (seepage). The model is implemented in a GIS (Geographic Information System) scripting language, which facilitate the use of complex three-dimensional (3D) topographies. The model is applied to and tested on the well-documented Super-Sauze landslide developed in reworked clay-shales. It is shown that the temporal and spatial varying moving pattern of the landslide can be reproduced. The numerical analysis reveals that viscous stresses produced by the fluid are irrelevant. Movements are mainly controlled by buoyancy, related to the evolution of the ground water level within the landslide that comes from water infiltration, and is introduced as a boundary condition. It is concluded that a two-phase, grain-fluid mixture model is convenient when landslide motion in fine-grained material is mainly controlled by the hydrological conditions (i.e. changes in pore water pressures), as in this example. The material parameters, as viscosity, calibrated to reproduce such landslide motion in models using the one-phase material approach, would take unrealistic values.

  11. Coarse-grained and fine-grained parallel optimization for real-time en-face OCT imaging

    NASA Astrophysics Data System (ADS)

    Kapinchev, Konstantin; Bradu, Adrian; Barnes, Frederick; Podoleanu, Adrian

    2016-03-01

    This paper presents parallel optimizations in the en-face (C-scan) optical coherence tomography (OCT) display. Compared with the cross-sectional (B-scan) imagery, the production of en-face images is more computationally demanding, due to the increased size of the data handled by the digital signal processing (DSP) algorithms. A sequential implementation of the DSP leads to a limited number of real-time generated en-face images. There are OCT applications, where simultaneous production of large number of en-face images from multiple depths is required, such as real-time diagnostics and monitoring of surgery and ablation. In sequential computing, this requirement leads to a significant increase of the time to process the data and to generate the images. As a result, the processing time exceeds the acquisition time and the image generation is not in real-time. In these cases, not producing en-face images in real-time makes the OCT system ineffective. Parallel optimization of the DSP algorithms provides a solution to this problem. Coarse-grained central processing unit (CPU) based and fine-grained graphics processing unit (GPU) based parallel implementations of the conventional Fourier domain (CFD) OCT method and the Master-Slave Interferometry (MSI) OCT method are studied. In the coarse-grained CPU implementation, each parallel thread processes the whole OCT frame and generates a single en-face image. The corresponding fine-grained GPU implementation launches one parallel thread for every data point from the OCT frame and thus achieves maximum parallelism. The performance and scalability of the CPU-based and GPU-based parallel approaches are analyzed and compared. The quality and the resolution of the images generated by the CFD method and the MSI method are also discussed and compared.

  12. Characterisation of excavated fine fraction and waste composition from a Swedish landfill.

    PubMed

    Jani, Yahya; Kaczala, Fabio; Marchand, Charlotte; Hogland, Marika; Kriipsalu, Mait; Hogland, William; Kihl, Anders

    2016-12-01

    The present research studies the characterisation and the physico-chemical properties of an excavated fine fraction (<10 mm) from a Swedish landfill, the Högbytorp. The results showed that the fine fraction represents 38% by mass of the total excavated wastes and it contains mainly soil-type materials and minerals. Higher concentrations of zinc, copper, barium and chromium were found with concentrations higher than the Swedish Environmental Protection Agency (EPA) for contaminated soil. The found moisture and organic contents of the fine fraction were 23.5% and 16.6%, respectively. The analysed calorific value (1.7 MJ kg(-1)), the potential of CH4 (4.74 m(3) t(-1) dry matter) and Total Organic Carbon (TOC) (5.6%) were low and offer low potential of energy. Sieving the fine fraction further showed that 80% was smaller than 2 mm. The fine represents a major fraction at any landfill (40%-70%), therefore, characterising the properties of this fraction is essential to find the potential of reusing/recycling or safely redisposing.

  13. Supercooled interfacial water in fine grained soils probed by dielectric spectroscopy

    NASA Astrophysics Data System (ADS)

    Lorek, A.; Wagner, N.

    2013-04-01

    Water as thermodynamic state parameter affects nearly all physical, chemical and biological processes on the earth. Recent Mars observations as well as laboratory investigations suggest that water is also a key factor of current physical and chemical processes on the martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid like state of water on martian analog soils in the temperature range below 0 °C. In this context, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine grained soils in the frequency range from 10 Hz to 1.1 MHz at martian like temperatures down to -70 °C. Two martian analogue soils have been investigated: a Ca-Bentonite (specific surface of 237 m2 g-1, up to 9.4% w/w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g-1, up to 7.4% w/w). Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak high frequency processes (bound or hydrated water as well as ice) and a strong low frequency process due to counter ion relaxation and the Maxwell-Wagner effect. To characterize the dielectric relaxation behavior, a generalized fractional dielectric relaxation model is applied assuming three active relaxation processes with relaxation time of the ith process according to an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid like water content by means of the Birchak or CRIM equation. There are evidence that Bentonite down to -70 °C has a liquid like water content of 1.17 monolayers and JSC Mars 1 a liquid like water content of 1.96 mono layers.

  14. Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy

    NASA Astrophysics Data System (ADS)

    Lorek, A.; Wagner, N.

    2013-12-01

    Water substantially affects nearly all physical, chemical and biological processes on the Earth. Recent Mars observations as well as laboratory investigations suggest that water is a key factor of current physical and chemical processes on the Martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid-like state of water on Martian analogue soils for temperatures below 0 °C. To this end, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine-grained soils in the frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to -70 °C. Two Martian analogue soils have been investigated: a Ca-bentonite (specific surface of 237 m2 g-1, up to 9.4% w / w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g-1, up to 7.4% w / w). Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak high-frequency processes (bound or hydrated water as well as ice) and a strong low-frequency process due to counter-ion relaxation and the Maxwell-Wagner effect. To characterize the dielectric relaxation behaviour, a generalized fractional dielectric relaxation model was applied assuming three active relaxation processes with relaxation time of the ith process modelled with an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid-like water content by means of the Birchak or CRIM equation. There are evidence that bentonite down to -70 °C has a liquid-like water content of 1.17 monolayers and JSC Mars 1 a liquid-like water content of 1.96 monolayers.

  15. Fine mapping of qGW1, a major QTL for grain weight in sorghum.

    PubMed

    Han, Lijie; Chen, Jun; Mace, Emma S; Liu, Yishan; Zhu, Mengjiao; Yuyama, Nana; Jordan, David R; Cai, Hongwei

    2015-09-01

    We detected seven QTLs for 100-grain weight in sorghum using an F 2 population, and delimited qGW1 to a 101-kb region on the short arm of chromosome 1, which contained 13 putative genes. Sorghum is one of the most important cereal crops. Breeding high-yielding sorghum varieties will have a profound impact on global food security. Grain weight is an important component of grain yield. It is a quantitative trait controlled by multiple quantitative trait loci (QTLs); however, the genetic basis of grain weight in sorghum is not well understood. In the present study, using an F2 population derived from a cross between the grain sorghum variety SA2313 (Sorghum bicolor) and the Sudan-grass variety Hiro-1 (S. bicolor), we detected seven QTLs for 100-grain weight. One of them, qGW1, was detected consistently over 2 years and contributed between 20 and 40 % of the phenotypic variation across multiple genetic backgrounds. Using extreme recombinants from a fine-mapping F3 population, we delimited qGW1 to a 101-kb region on the short arm of chromosome 1, containing 13 predicted gene models, one of which was found to be under purifying selection during domestication. However, none of the grain size candidate genes shared sequence similarity with previously cloned grain weight-related genes from rice. This study will facilitate isolation of the gene underlying qGW1 and advance our understanding of the regulatory mechanisms of grain weight. SSR markers linked to the qGW1 locus can be used for improving sorghum grain yield through marker-assisted selection.

  16. Evaluation of the Parameters Affecting the Cohesion of Fine Grained Soil

    NASA Astrophysics Data System (ADS)

    Vondráčková, Terezie; Kmec, Ján; Čejka, Jiří; Bartuška, Ladislav; Stopka, Ondrej

    2016-10-01

    Cohesion of the soils is one of the most important parameters which soil is evaluated in terms of its suitability for building foundations. Safety of construction is in fact dependent on the strength of soil, respectively shear strength. Fine-grained soil represents very specific group, in which is distinguished an effective and total cohesion of soils. The water in the soil thus drastically affects its cohesion contrary to gravel and sandy soils. The publication compares the tabular values of the effective and total cohesion and define the influence of water, grain size and consistency of her behaviour.

  17. Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

    PubMed Central

    Lu, Man; Wang, Xingxing; Sun, Guowei; Qin, Bing; Xiao, Jinzhou; Yan, Shuling; Pan, Yingjie; Wang, Yongjie

    2014-01-01

    Tibetan kefir grains (TKGs), a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i) yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii) the diversity of yeasts is relatively low on genus level with three dominant species – Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii) S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic associations between S

  18. The dynamics of fine-grain sediment dredged from Santa Cruz Harbor

    USGS Publications Warehouse

    Storlazzi, Curt D.; Conaway, Christopher H.; Presto, M. Katherine; Logan, Joshua B.; Cronin, Katherine; van Ormondt, Maarten; Lescinski, Jamie; Harden, E. Lynne; Lacy, Jessica R.; Tonnon, Pieter K.

    2011-01-01

    In the fall and early winter of 2009, a demonstration project was done at Santa Cruz Harbor, California, to determine if 450 m3/day of predominantly (71 percent) mud-sized sediment could be dredged from the inner portion of the harbor and discharged to the coastal ocean without significant impacts to the beach and inner shelf. During the project, more than 7600 m3 of sediment (~5400 m3 of fine-grain material) was dredged during 17 days and discharged approximately 60 m offshore of the harbor at a depth of 2 m on the inner shelf. The U.S. Geological Survey's Pacific Coastal and Marine Science Center was funded by the U.S. Army Corps of Engineers and the Santa Cruz Port District to do an integrated mapping and process study to investigate the fate of the mud-sized sediment dredged from the inner portion of Santa Cruz Harbor and to determine if any of the fine-grain material settled out on the shoreline and/or inner shelf during the fall and early winter of 2009. This was done by collecting highresolution oceanographic and sediment geochemical measurements along the shoreline and on the continental shelf of northern Monterey Bay to monitor the fine-grain sediment dredged from Santa Cruz Harbor and discharged onto the inner shelf. These in place measurements, in conjunction with beach, water column, and seabed surveys, were used as boundary and calibration information for a three-dimensional numerical circulation and sediment dynamics model to better understand the fate of the fine-grain sediment dredged from Santa Cruz Harbor and the potential consequences of disposing this type of material on the beach and on the northern Monterey Bay continental shelf.

  19. Detecting Densely Distributed Graph Patterns for Fine-Grained Image Categorization.

    PubMed

    Zhang, Luming; Yang, Yang; Wang, Meng; Hong, Richang; Nie, Liqiang; Li, Xuelong

    2016-02-01

    Fine-grained image categorization is a challenging task aiming at distinguishing objects belonging to the same basic-level category, e.g., leaf or mushroom. It is a useful technique that can be applied for species recognition, face verification, and so on. Most of the existing methods either have difficulties to detect discriminative object components automatically, or suffer from the limited amount of training data in each sub-category. To solve these problems, this paper proposes a new fine-grained image categorization model. The key is a dense graph mining algorithm that hierarchically localizes discriminative object parts in each image. More specifically, to mimic the human hierarchical perception mechanism, a superpixel pyramid is generated for each image. Thereby, graphlets from each layer are constructed to seamlessly capture object components. Intuitively, graphlets representative to each super-/sub-category is densely distributed in their feature space. Thus, a dense graph mining algorithm is developed to discover graphlets representative to each super-/sub-category. Finally, the discovered graphlets from pairwise images are integrated into an image kernel for fine-grained recognition. Theoretically, the learned kernel can generalize several state-of-the-art image kernels. Experiments on nine image sets demonstrate the advantage of our method. Moreover, the discovered graphlets from each sub-category accurately capture those tiny discriminative object components, e.g., bird claws, heads, and bodies.

  20. The Onset of Anelastic Behaviour in Fine-Grained Olivine at High Temperature

    NASA Astrophysics Data System (ADS)

    Jackson, I.; David, E.; Faul, U.

    2013-12-01

    With increasing temperature, fine-grained polycrystalline materials undergo a transition from elastic to anelastic behaviour, involving grain-boundary sliding recoverably accommodated by elastic distortion of adjacent grains - according to the classic theory of Raj and Ashby. This model, recently revisited by Morris and his colleagues, predicts shear-mode dissipation localised in temperature-period space as a 1/Q peak with height of order 0.01. Experimental data for fine-grained polycrystalline olivine are yet to provide unequivocal evidence of the expected dissipation peak and associated dispersion of the shear modulus. Accordingly, we have embarked on a new series of measurements on synthetic olivine polycrystals in which the specimens are enclosed within copper, rather than the usual steel, jackets for the forced-oscillation experiments at high temperature and pressure. In this way, we avoid the complicating effects of uncertainties in the mechanical behaviour of the jacket arising from the sluggish ferrite-austenite phase transition in mild steel. An exploratory torsional forced-oscillation experiment has already yielded a tantalising glimpse of a possible dissipation peak. The results of follow-up torsional-oscillation tests on more nearly optimal specimens, tested over a wider range of temperature, will be described. We will also report constraints on the recoverability of the inelastic strain from complementary microcreep tests, and the outcomes of exploratory flexural-oscillation measurements.

  1. Source discrimination of fine-grained deposits occurring on marine beaches: The Calvados beaches (eastern Bay of the Seine, France)

    NASA Astrophysics Data System (ADS)

    Dubrulle, C.; Lesueur, P.; Boust, D.; Dugué, O.; Poupinet, N.; Lafite, R.

    2007-03-01

    In tide-dominated systems, fine-grained deposits occur in intertidal areas of inner estuaries as loci of convergence of fluvial and marine material. Even in the vicinity of estuaries, mud deposits are rare on open sandy beaches. This study focuses on temporary occurrences of muddy sediments on marine beaches along the Calvados coastline in Normandy, adjacent to the macrotidal Seine estuary (France). Clay mineralogy, major-minor-trace elements and radionuclides were used as particulate markers to determine the provenance of the mud deposits. The fine fraction, defined here as particles <50 μm, was analysed, in surficial muddy sediments on seven beaches between the Seine estuary and the Orne river mouth, sampled between February 2002 and June 2003. The deposits were compared to earlier Holocene relict deposits, which crop out on some beaches and on the shoreface, and to Mesozoic marls and limestones, which have detached from the coastal cliffs. The use of the three types of particulate markers revealed no significant seasonal or geographical variations between the beaches. The muddy deposits were made up of the same sedimentary pool of particles. The clay mineralogical and geochemical characteristics of these mud deposits enabled modern (i.e. present-day and earlier Holocene fine silts and clays) to be distinguished from ancient (i.e. Mesozoic) sediments. The use of radionuclides ( 60Co and 137Cs) confirmed the marine influence in the modern deposits, with a decreasing gradient along the Calvados beaches towards the east. The presence of several specific major-minor-trace elements (e.g. Ti, P) revealed that some of the fine material originated in the Seine estuary. Despite the occurrence of easily erodable rocks (i.e. clays, marls and limestones) in the coastal cliffs, this source represented a limited supply, which is only of local significance. Small rivers, such as the Orne, Dives and Touques which discharge in the study area act as secondary suppliers of fine-grained

  2. Temperature Dependence of the Strength of Fine- and Ultrafine-Grained Materials

    SciTech Connect

    Schneibel, J H; Heilmaier, M.; Blum, W; Hasemann, G; Shanmugasundaram, T

    2011-01-01

    The yield stress of oxide dispersion-strengthened (ODS) PM2000 steel and nanocluster-strengthened (NCS) 14YWT steel was measured as a function of temperature for grain sizes from 0.2 {micro}m to {infinity}. In combination with data from the literature, it was found that the indirect strengthening (i.e., the Hall-Petch strengthening) for small grain sizes was often greater than the direct strengthening (i.e., the Orowan strengthening due to the dispersoids). The yield stress dropped significantly at a transition temperature near 500 C even though the grain size remained constant. For small grain sizes, a large fraction of this drop was attributed to a decrease in grain size strengthening. Three published models describing this effect were compared with the experimental data. The observed transition temperatures were consistent with two of them. The strength-temperature curves for PM2000 with different grain sizes tended to intersect, whereas those for 14YWT did not. Because of this feature, the description of the strength-temperature dependence of 14YWT could be narrowed down to a single model. It is concluded that ODS and NCS materials are well suited to examining the temperature dependence of grain size strengthening.

  3. Formation of a fine-grained microstructure in Al-Mg-Mn-Zr alloy by the conventional method

    NASA Astrophysics Data System (ADS)

    Kulitskiy, V.; Mogucheva, A.; Kaibyshev, R.

    2016-11-01

    The material is rolled at ambient temperature with the total reduction 80%, and then recrystallization annealing is carried out in the temperature interval 300-400°C for 2 hours. A partial recrystallization occurred after annealing at temperatures below 320°C. The annealing temperature increase from 320 to 400°C leads to the formation of a recrystallized equiaxed microstructure with the grain size of about 6-12 µm. Based on detailed microstructural examinations, a comparison of microstructure-strength relationships is carried out. The investigation of the fine microstructure reveals a low dislocation density and low fraction of low-angle boundaries (LABs). The analysis of transmission electron microscopy (TEM) micrographs shows a uniform distribution of Al6Mn particles and retention of the dispersoid size and morphology throughout the process. The increase in the recrystallization annealing temperature above 320°C has a slight effect on the alloy microhardness.

  4. Data Quality Objectives Summary Report for Characterization of Fine Grained Sediments at Area C

    SciTech Connect

    PETERSEN, S.W.

    2003-09-04

    Approximately 200 surface barriers will be required to cover waste sites on the Central Plateau. These barriers will serve to limit or eliminate recharge through the waste sites, effectively isolating contamination from the underlying groundwater. Barrier design will begin in fiscal year (FY) 2004 in support of U Plant waste site closure; construction of these barriers is scheduled to begin in FY 2005. A vital part of barrier design is the evapotranspiration (ET) layer. This is the top layer, which retains precipitation during the rainy season and allows it to evaporate and/or be transpired by plants in the dry season. This layer will consist of fine-grained silt/loam, which only occurs in a few areas on and near the Hanford Site. A large volume of this type of soil is needed to meet the needs of waste site barrier construction at the U Plant waste sites, the BIC Cribs areas, and other 200 Area waste sites. A previous study (BHI-01551, ''Alternative Fine-Grained Soil Borrow Source Study Find Report'') that investigated four borrow source areas on or near the Hanford Site concluded that Area C, located south of the Rattlesnake Barricade and Highway 240, is the only site with the potential to meet the needs of the numerous 200 Area waste sites. The data indicate that Area C has substantial reserves, and that it occurs as a continuous body suitable for exploitation. The amount of suitable material identified in BHI-01551 carried a large uncertainty, with volume estimates ranging from 1.9 to 6.6 million m3. This data quality objective (DQO) is being performed to reduce the uncertainties associated with the fine-grained borrow soils in Area C suitable for use as an ET barrier. This DQO summary report focuses on identifying the types and amount of data that must be collected to confirm that enough suitable and exploitable fine-grained soils are available in Area C to meet construction requirements for 200 Area surface barriers. This effort directly supports remediation

  5. Dunes versus ripples in deep-water, fine-grained sediments

    NASA Astrophysics Data System (ADS)

    Masalimova, L.; Lowe, D. R.

    2012-12-01

    The Lower Mount Messenger Formation (LMMF) is characterized by fine- to very fine-grained sediments. While the grain size doesn't change much within the formation, the sedimentary structures do. Perhaps the most striking difference between the channels in the upper part of the LMMF and the lobes in the lower part of the LMMF is the abundance of large-scale, climbing-dune cross-stratification in the lobes and of small-scale, climbing-ripple cross-lamination within channels. The sole presence of climbing dunes in fine-grained sandstones in deep-water lobe complex is surprising. Firstly, dunes are characteristic features largely in fluvial environments. Cross-stratification is not a widespread sedimentary structure in deep-water, part of the reason might be the difficulty in recognizing subtle stratification in weathered outcrop. The absence can be also explained by the fact that the flows might be insufficiently deep or there is never sufficient time for dune formation. Secondly, the hydraulics of the cross-stratification requires sand coarser than 0.2 mm (middle fine sand) to form dunes based on flume experiments. The cross-stratification mostly was documented in deep-water in coarse-grained sediments such as pebbles and gravels in southern Chile and in Quebec, medium to granule-grade sands in Oceanographer Canyon, and medium to coarse-grained sands in the Eocene Hecho Group, etc. Nevertheless, the dunes are documented in fine-grained systems such as Brushy Canyon Formation (the authors use "plow-and-fill" term instead of "dunes"). Thirdly, the cross-stratification is generally documented in confined setting such as channels and scours. But this study shows that the cross-stratification can be present in largely unconfined depositional setting of the LMMF. We postulate that the dunes found in the LMMF can be unusually high ripples from the hydrodynamic point of view. Considering the facts that (1) ripples are different from dunes in outcrop by size and the size of

  6. Flood-related variations in provenance of fine-grained palaeochannel sediments in the Rhine river basin

    NASA Astrophysics Data System (ADS)

    van der Perk, Marcel; Toonen, Willem H. J.; Ypma, Jochem; Brewer, Paul A.; Prins, Maarten A.; Macklin, Mark G.; Middelkoop, Hans

    2014-05-01

    In this study, we examine flood-related variations in provenance of fine-grained palaeochannel sediments from the Bienener Altrhein (Germany), an abandoned river channel close to the apex of the Rhine river delta. Geochemical and grain size analyses were conducted on channel-fill sediments from multiple core sections, ranging from 1.15 m to 8.48 m depth, which represents pre-industrial sediment deposited from approximately 1550 AD to 1850 AD. In addition, four sediment cores of ~ 1 m length were retrieved from channel-fills or overbank deposits along the Upper Rhine and the three main tributaries of the Rhine in Germany (Neckar River, Main River and Moselle River). Sediment geochemistry was analysed using an Itrax X-Ray Fluorescence (XRF) core scanner. Four elements (Ti, Co, Rb, W) were selected for further analysis based on the following a priori criteria: (1) The elements must be associated with minerals in the fine particle size fractions; 2) they must not be susceptible to precipitation-dissolution reactions during early diagenenis of the sediment; 3) the elements must be detected in the vast majority of the measurements; 4) the difference between the minimum and maximum number of the XRF counts for the upstream cores must be greater than 50% of the average number of counts. The XRF counts for these elements were standardised to z-scores and were subsequently corrected for the variation clay content (< 2 μm) within the core and between the upstream cores by means of linear regression. The Mahalanobis distance was adopted as a measure of dissimilarity between the Bienener Altrhein sediment increments and the sediment from the upstream tributaries. The logtransformed Mahalanobis distances to the mean sediment composition of the upstream sediments were correlated to the medium to coarse sand particle size fraction (> 150 μm), which was primarily deposited during historical flood events. The results show the Mahalanobis distances are larger than 1 for most

  7. Spatial distribution of defects in ultra fine grained copper prepared by high pressure torsion

    NASA Astrophysics Data System (ADS)

    Čížek, J.; Melikhova, O.; Procházka, I.; Janeček, M.; Hruška, P.; Dobatkin, S.

    2016-01-01

    Bulk materials with ultra fine grain structure can be fabricated by severe plastic deformation. Among variety of techniques based on severe plastic deformation high pressure torsion is the most efficient method for grain refinement down to nano-scale. In torsion deformation the strain distribution across the sample is non-uniform and increases with increasing radial distance from the centre of the sample corresponding to the axis of torsional straining. Due to this reason it is very important to examine homogeneity of ultra fine grained structure of samples prepared by high pressure torsion. In the present work positron annihilation spectroscopy was employed for mapping of spatial distribution of defects in ultra fine grained copper prepared by high pressure torsion. Spatial distribution of defects was examined by means of (i) Doppler broadening using S parameter for mapping of defect density and (ii) positron lifetime spectroscopy. Spatially resolved positron annihilation studies were combined with mapping by microhardness testing. Hardness is sensitive to dislocation density due to work hardening but is practically not affected by vacancies while positron annihilation is sensitive both to dislocations and vacancies. Our investigations revealed that ultra fine grained copper contains dislocations and vacancy clusters created by agglomeration of deformation-induced vacancies. Average size of vacancy clusters increases with increasing radial distance from the centre of the sample due to higher production rate of vacancies resulting in larger clusters. During high pressure torsion deformation microhardness increases firstly at the periphery of the sample due to the highest imposed strain. With increasing number of high pressure torsion revolutions the hardness increases also in the centre and finally becomes practically uniform across the whole sample indicating the homogeneous distribution of dislocations. Doppler broadening mapping revealed a remarkable increase of

  8. Fine grained Ba(1-x)Sr(x)TiO3 ceramics by spark plasma sintering.

    PubMed

    Tian, Huyong; Chen, Wanpin; Buckley, C E; Chan, H L W

    2008-11-01

    Fine grained Ba(0.75)Sr(0.25)TiO3 (BST) ceramics were prepared via spark plasma sintering technique. BST nano-powders freshly prepared by a low-temperature direct solution synthesis technique were used as starting materials. X-ray diffraction measurements indicated that the ceramics had a pure perovskite phase and the observation under scanning electron microscope revealed that the ceramic had a grain size in the range of 50 to 300 nm. The dielectric properties of the fine-grained BST ceramics were determined at different temperatures and frequencies. At room temperature, the ceramics exhibited a moderate dielectric constant (3962 +/- 10), a good dielectric tunability (53.84% under a dc bias of 19.72 kV/cm). The highest tunability and figure of merit (FOM) values are 83.27% at 50.2 degrees C and 289.28 at 62.3 degrees C, respectively. These results suggested that the BST ceramics are suitable for use in tunable microwave devices.

  9. HIGH-STRAIN RATE RESPONSE OF ULTRA-FINE GRAINED COPPER: EXPERIMENTS AND ANALYSIS

    SciTech Connect

    Mishra, Anuj; Kad, Bimal; Martin, Morgana; Thadhani, Naresh; Kenik, Edward A; Myers, Marc A.

    2008-07-01

    The high-strain rate response of ultra-fine grained (UFG) copper processed by Equal Channel Angular Pressing (ECAP) was characterized by reverse Taylor impact and Hopkinson-bar experiments. Two types of copper samples are tested using Hopkinson bar: (a) cylindrical samples to investigate the response at high strain-rates,(b) hat shaped samples to compare the shear band characteristics in UFG copper with the ones that have been studied in coarse grained samples. This can be attributed to the high strain-rate sensitivity of the fine grained FCC metals. Upon impact, the samples were found to undergo heat induced static recrystallization at a calculated temperature of 360K, indicating that the UFG copper is thermally unstable. Reverse Taylor tests were conducted on as-received OFHC Cu rod and ECAP specimens with sequential ECAP passes (2 and 8). The dynamic deformations of the samples are modeled using AUTODYN-2D and a modified Johnson-Cook constitutive equation was found to capture the dynamic response. Similar to the compression test results, the impacted front of the samples were found to recrystallize extensively and preferentially.

  10. Fabrication of fine-grain tantalum diffusion barrier tube for Nb{sub 3}Sn conductors

    SciTech Connect

    Hartwig, K. T.; Balachandran, S.; Mezyenski, R.; Seymour, N.; Robinson, J.; Barber, R. E.

    2014-01-27

    Diffusion barriers used in Nb{sub 3}Sn wire are often fabricated by wrapping Ta sheet into a tube with an overlap seam. A common result of such practice is non-uniform deformation in the Ta sheet as it thins by wire drawing because of non-uniform grain size and texture in the original Ta sheet. Seamless Ta tube with a fine-grain and uniform microstructure would be much better for the diffusion barrier application, but such material is expensive and difficult to manufacture. This report presents results on a new fabrication strategy for Ta tube that shows promise for manufacture of less costly tube with an improved microstructure. The fabrication method begins with seam-welded tube but gives a fine-grain uniform microstructure with little difference between the longitudinal seam weld region and the parent metal after post-weld processing. Severe plastic deformation processing (SPD) applied by area reduction extrusion and tube equal channel angular extrusion (tECAE) are used to refine and homogenize the microstructure. Microstructure and mechanical property results are presented for Ta tubes fabricated by this new processing strategy.

  11. Friction and Wear of Ion-Beam-Deposited Diamondlike Carbon on Chemical-Vapor-Deposited, Fine-Grain Diamond

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.; Lanter, William C.

    1996-01-01

    Friction and wear behavior of ion-beam-deposited diamondlike carbon (DLC) films coated on chemical-vapor-deposited (CVD), fine-grain diamond coatings were examined in ultrahigh vacuum, dry nitrogen, and humid air environments. The DLC films were produced by the direct impact of an ion beam (composed of a 3:17 mixture of Ar and CH4) at ion energies of 1500 and 700 eV and an RF power of 99 W. Sliding friction experiments were conducted with hemispherical CVD diamond pins sliding on four different carbon-base coating systems: DLC films on CVD diamond; DLC films on silicon; as-deposited, fine-grain CVD diamond; and carbon-ion-implanted, fine-grain CVD diamond on silicon. Results indicate that in ultrahigh vacuum the ion-beam-deposited DLC films on fine-grain CVD diamond (similar to the ion-implanted CVD diamond) greatly decrease both the friction and wear of fine-grain CVD diamond films and provide solid lubrication. In dry nitrogen and in humid air, ion-beam-deposited DLC films on fine-grain CVD diamond films also had a low steady-state coefficient of friction and a low wear rate. These tribological performance benefits, coupled with a wider range of coating thicknesses, led to longer endurance life and improved wear resistance for the DLC deposited on fine-grain CVD diamond in comparison to the ion-implanted diamond films. Thus, DLC deposited on fine-grain CVD diamond films can be an effective wear-resistant, lubricating coating regardless of environment.

  12. Nontoxic chemical process for in situ permeability enhancement and accelerated decontamination of fine-grain subsurface sediments

    DOEpatents

    Kansa, Edward J.; Wijesinghe, Ananda M.; Viani, Brian E.

    1997-01-01

    The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments. The invention uses cationic flocculents and organic solvents to collapse the swelling negative double layer surrounding water saturated clay particles, causing a flocculated, cracked clay structure. The modification of the clay fabric in fine-grained sediments dramatically increases the hydraulic conductivity of previously very tight clays many orders of magnitude.

  13. Nontoxic chemical process for in situ permeability enhancement and accelerated decontamination of fine-grain subsurface sediments

    DOEpatents

    Kansa, E.J.; Wijesinghe, A.M.; Viani, B.E.

    1997-01-14

    The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments. The invention uses cationic flocculants and organic solvents to collapse the swelling negative double layer surrounding water saturated clay particles, causing a flocculated, cracked clay structure. The modification of the clay fabric in fine-grained sediments dramatically increases the hydraulic conductivity of previously very tight clays many orders of magnitude. 8 figs.

  14. Fine Grained Silicon-Tungsten Calorimetry for a Linear Collider Detector

    SciTech Connect

    Strom, D.; Frey, R.; Breidenbach, M.; Freytag, D.; Graf, N.; Haller, G.; Milgrome, O.; Radeka, V.; /Brookhaven

    2006-02-08

    A fine grained silicon-tungsten calorimeter is ideal for use as the electromagnetic calorimeter in a linear collider detector optimized for particle-flow reconstruction. We are designing a calorimeter that is based on readout chips which are bump bonded to the silicon wafers that serve as the active medium in the calorimeter. By using integrated electronics we plan to demonstrate that fine granularity can be achieved at a reasonable price. Our design minimizes the gap between tungsten layers leading to a small Moliere radius, an important figure of merit for particle-flow detectors. Tests of the silicon detectors to be used in a test beam prototype as well as timing measurements based on similar silicon detectors are discussed.

  15. Plasma Processed Nanosized-Powders of Refractory Compounds for Obtaining Fine-Grained Advanced Ceramics

    NASA Astrophysics Data System (ADS)

    I, Zalite; J, Grabis; E, Palcevskis; M, Herrmann

    2011-10-01

    One of the ways for the production of ceramic materials with a fine-grained structure is the use of nanopowders. Different methods are used for the production of nanopowders. One of them is the method of plasmachemical synthesis. Different nanopowders of refractory materials can be obtained by this method. The preparation of nanosized powders of nitrides and oxides and their composites by the method of plasmachemical synthesis, the possibilities to receive nanopowders with different particle size and the potential advantages of nanopowders were investigated.

  16. Thermal and microstructural properties of fine-grained material at the Viking Lander 1 site

    NASA Astrophysics Data System (ADS)

    Paton, M. D.; Harri, A.-M.; Savijärvi, H.; Mäkinen, T.; Hagermann, A.; Kemppinen, O.; Johnston, A.

    2016-06-01

    As Viking Lander 1 touched down on Mars one of its footpads fully penetrated a patch of loose fine-grained drift material. The surrounding landing site, as observed by VL-1, was found to exhibit a complex terrain consisting of a crusted surface with an assortment of rocks, large dune-like drifts and smaller patches of drift material. We use a temperature sensor attached to the buried footpad and covered in fine-grained material to determine the thermal properties of drift material at the VL-1 site. The thermal properties are used to investigate the microstructure of the drift material and understand its relevance to surface-atmosphere interactions. We obtained a thermal inertia value of 103 ± 22 tiu. This value is in the upper range of previous thermal inertia estimates of martian dust as measured from orbit and is significantly lower than the regional thermal inertia of the VL-1 site, of around 283 tiu, obtained from orbit. We estimate a thermal inertia of around 263 ± 29 tiu for the duricrust at the VL-1 site. It was noted the patch of fine-grained regolith around the footpad was about 20-30 K warmer compared to similar material beyond the thermal influence of the lander. An effective diameter of 8 ± 5 μm was calculated for the particles in the drift material. This is larger than atmospheric dust and large compared to previous estimates of the drift material particle diameter. We interpret our results as the presence of a range of particle sizes, <8 μm, in the drift material with the thermal properties being controlled by a small amount of large particles (∼8 μm) and its cohesion being controlled by a large amount of smaller particles. The bulk of the particles in the drift material are therefore likely comparable in size to that of atmospheric dust. The possibility of larger particles being locked into a fine-grained material has implications for understanding the mobilisation of wind blown materials on Mars.

  17. Near-Threshold Fatigue Crack Growth Behavior of Fine-Grain Nickel-Based Alloys

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Piascik, Robert S.

    2003-01-01

    Constant-Kmax fatigue crack growth tests were performed on two finegrain nickel-base alloys Inconel 718 (DA) and Ren 95 to determine if these alloys exhibit near-threshold time-dependent crack growth behavior observed for fine-grain aluminum alloys in room-temperature laboratory air. Test results showed that increases in K(sub max) values resulted in increased crack growth rates, but no evidence of time-dependent crack growth was observed for either nickel-base alloy at room temperature.

  18. Fine-Grained Rims in the Allan Hills 81002 and Lewis Cliff 90500 CM2 Meteorites: Their Origin and Modification

    NASA Technical Reports Server (NTRS)

    Hua, X.; Wang, J.; Buseck, P. R.

    2002-01-01

    Antarctic CM meteorites Allan Hills (ALH) 8 1002 and Lewis Cliff (LEW) 90500 contain abundant fine-grained rims (FGRs) that surround a variety of coarse-grained objects. FGRs from both meteorites have similar compositions and petrographic features, independent of their enclosed objects. The FGRs are chemically homogeneous at the 10 m scale for major and minor elements and at the 25 m scale for trace elements. They display accretionary features and contain large amounts of volatiles, presumably water. They are depleted in Ca, Mn, and S but enriched in P. All FGRs show a slightly fractionated rare earth element (REE) pattern, with enrichments of Gd and Yb and depletion of Er. Gd is twice as abundant as Er. Our results indicate that those FGRs are not genetically related to their enclosed cores. They were sampled from a reservoir of homogeneously mixed dust, prior to accretion to their parent body. The rim materials subsequently experienced aqueous alteration under identical conditions. Based on their mineral, textural, and especially chemical similarities, we conclude that ALH 8 1002 and LEW 90500 likely have a similar or identical source.

  19. K/Ar Dating of Fine Grained Sediments Near Prydz Bay, Antarctica: East Antarctic Ice Sheet Behavior During the Middle-Miocene Climate Transition

    NASA Astrophysics Data System (ADS)

    Duchesne, A. E.; Pierce, E. L.; Williams, T.; Hemming, S. R.; Johnson, D. L.; May, T.; Gombiner, J.; Torfstein, A.

    2012-12-01

    ¶ The Middle Miocene Climate Transition (MMCT) (~14 Ma) represents a time of major East Antarctic Ice-Sheet (EAIS) expansion, with research suggesting major global sea level fall on the order of ~60 meters (John et al., 2011, EPSL). Ocean Drilling Program (ODP) core data from Site 1165B near Prydz Bay shows an influx of cobbles deposited ~13.8-13.5 Ma, representing a sudden burst of ice-rafted detritus (IRD) during the MMCT. Based on 40Ar/39Ar dating of hornblendes and/or biotite grains, 5 of 6 dated pebbles from a companion study show Wilkes Land origins, indicating transport from over 1500 kilometers away. However, samples throughout this time interval have an anomalously low abundance of sand, thus we seek to understand the sedimentary processes that led to the deposition of these isolated dropstones in a fine matrix through provenance studies of the core's terrigenous fine fraction. Geochemical provenance studies of the terrigenous fraction of marine sediments can aid in identifying past dynamic EAIS behavior; the few outcrops available on the continent provide specific rock characterizations and age constraints from which cored marine sediments can then be matched to using established radiogenic isotope techniques. Here we apply the K/Ar dating method as a provenance tool for identifying the source area(s) of fine-grained terrigenous sediments (<63 μm) deposited during the MMCT. ¶ After source area characterization, we find that the fine-grained sediments from the mid-Miocene show a mixture of both local Prydz Bay sourcing (~400 Ma signature) and Wilkes Land provenance (~900 Ma signature). While locally-derived Prydz Bay sediments are likely to have been delivered via meltwater from ice and deposited as hemipelagic sediments (with some possible bottom current modification, as this is a drift site), sediments sourced from Wilkes Land required transport via large icebergs. Future work will involve further provenance determination on both the fine-grained

  20. Optimizing Fine-grained Communication in a Biomolecular Simulation Application on Cray XK6

    SciTech Connect

    Sun, Yanhua; Zheng, Gengbin; Mei, Chao; Phillips, James C.; Kale, Laxmikant V; Jones, Terry R

    2012-01-01

    Achieving good scaling for fine-grained communication intensive applications on modern supercomputers remains challenging. In our previous work, we have shown that such an application NAMD scales well on the full Jaguar XT5 without long-range interactions; Yet, with them, the speedup falters beyond 64K cores. Although the new Gemini interconnect on Cray XK6 has improved network performance, the challenges remain, and are likely to remain for other such networks as well. We analyze communication bottlenecks in NAMD and its CHARM++ runtime, using the Projections performance analysis tool. Based on the analysis, we optimize the runtime, built on the uGNI library for Gemini. We present several techniques to improve the fine-grained communication. Consequently, the performance of running 92224-atom Apoa1 with GPUs on TitanDev is improved by 36%. For 100-million-atom STMV, we improve upon the prior Jaguar XT5 result of 26 ms/step to 13 ms/step using 298,992 cores on Jaguar XK6.

  1. Webly-supervised Fine-grained Visual Categorization via Deep Domain Adaptation.

    PubMed

    Xu, Zhe; Huang, Shaoli; Zhang, Ya; Tao, Dacheng

    2016-12-08

    Learning visual representations from web data has recently attracted attention for object recognition. Previous studies have mainly focused on overcoming label noise and data bias and have shown promising results by learning directly from web data. However, we argue that it might be better to transfer knowledge from existing human labeling resources to improve performance at nearly no additional cost. In this paper, we propose a new semi-supervised method for learning via web data. Our method has the unique design of exploiting strong supervision, i.e., in addition to standard image-level labels, our method also utilizes detailed annotations including object bounding boxes and part landmarks. By transferring as much knowledge as possible from existing strongly supervised datasets to weakly supervised web images, our method can benefit from sophisticated object recognition algorithms and overcome several typical problems found in webly-supervised learning. We consider the problem of fine-grained visual categorization, in which existing training resources are scarce, as our main research objective. Comprehensive experimentation and extensive analysis demonstrate encouraging performance of the proposed approach, which, at the same time, delivers a new pipeline for fine-grained visual categorization that is likely to be highly effective for real-world applications.

  2. Visual classification of very fine-grained sediments: Evaluation through univariate and multivariate statistics

    USGS Publications Warehouse

    Hohn, M. Ed; Nuhfer, E.B.; Vinopal, R.J.; Klanderman, D.S.

    1980-01-01

    Classifying very fine-grained rocks through fabric elements provides information about depositional environments, but is subject to the biases of visual taxonomy. To evaluate the statistical significance of an empirical classification of very fine-grained rocks, samples from Devonian shales in four cored wells in West Virginia and Virginia were measured for 15 variables: quartz, illite, pyrite and expandable clays determined by X-ray diffraction; total sulfur, organic content, inorganic carbon, matrix density, bulk density, porosity, silt, as well as density, sonic travel time, resistivity, and ??-ray response measured from well logs. The four lithologic types comprised: (1) sharply banded shale, (2) thinly laminated shale, (3) lenticularly laminated shale, and (4) nonbanded shale. Univariate and multivariate analyses of variance showed that the lithologic classification reflects significant differences for the variables measured, difference that can be detected independently of stratigraphic effects. Little-known statistical methods found useful in this work included: the multivariate analysis of variance with more than one effect, simultaneous plotting of samples and variables on canonical variates, and the use of parametric ANOVA and MANOVA on ranked data. ?? 1980 Plenum Publishing Corporation.

  3. Mechanical, hydric and thermal properties of fine-grained high performance concrete

    NASA Astrophysics Data System (ADS)

    KoÅáková, D.; Čáchová, M.; Doleželová, M.; Kočí, V.; Vejmelková, E.; Černý, R.

    2017-02-01

    The experimental analysis of several types of fine-grained high performance concretes is presented in this paper. Besides mechanical parameters, presented analysis aims also at determination of basic physical and heat and moisture transport and storage parameters. Within the frame of this paper, three different mixtures of fine-grained high performance concrete were designed, distinguished by the type of binder (unitary-, binary- or ternary-based) and their properties were compared with two types common concretes. Experimental results show that the compressive and bending strength, static modulus of elasticity of high performance concretes are significantly better than for other two concrete mixtures, regardless of the type of binder. Thermal conductivity of high performance concretes was higher in dry state, but due to lower open porosity and lower values of moisture diffusivity these concretes are more resistance to liquid moisture intake, therefore they evince better thermal properties in fully saturated state. Since the ternary-based high performance concrete contains also secondary raw materials as partial cement replacement and its properties were mostly better than other investigated concretes, it can be considered as an environmental friendly solution.

  4. Method for manufacturing metal from fine-grain metal-oxide material

    SciTech Connect

    Edstrom, J.O.; Gorling, K.G.

    1984-02-28

    A method for producing fine-grain iron-containing metal oxide material, the method comprising a first reduction stage wherein the oxide material is at least partially reduced in a fluidized state at a temperature of approximately 1025/sup 0/-1275/sup 0/ K. by a reducing gas which is carbon monoxide or carbon monoxide mixed with hydrogen, followed by a smelting and final reduction stage to form a metal melt, the reducing gas used for the first reduction stage obtained from the smelting and final reduction stage. Prior to the first reduction stage, relatively large cakes or shaped pieces are formed from the fine-grain metal-oxide material in the presence of moisture and a hydraulic binder and the cakes or pieces caused to harden. The hardened oxide material is disintegrated and classified to form the starting material for the first reduction stage and is given a particle size distribution such that the material forms a fluidized bed which is substantially stationary at the considerable gas velocity required to carrying out the reduction process without bogging at the temperature selected for the first reduction stage.

  5. Fine-grained bird recognition by using contour-based pose transfer

    NASA Astrophysics Data System (ADS)

    Zhu, Leqing; Lv, Yaoyao; Zhang, Daxing; Zhou, Yadong; Yan, Guoli; Wang, Huiyan; Wang, Xun

    2015-10-01

    We propose a pose transfer method for fine-grained classifications of birds that have wide variations in appearance due to different poses and subcategories. Specifically, bird pose is transferred by using Radon-transform-based contour descriptor, k-means clustering, and K nearest neighbors (KNN) classifier. During training, we clustered annotated image samples into certain poses based on their normalized part locations and used the cluster centers as their consistent part constellations for a particular pose. At the testing stage, Radon-transform-based contour descriptor is used to find the pose a sample belongs to with a KNN classifier by using cosine similarity, and normalized part constellations are transferred to the unannotated image according to the pose type. Bag-of-visual words with OpponentSIFT and color names extracted from each part and from the global image are concatenated as feature vector, which is input to support vector machine for classification. Experimental results demonstrate significant performance gains from our method on the Caltech-UCSD Birds-2011 dataset for the fine-grained bird classification task.

  6. Identification of Highly Fractionated 18O-Rich Silicate Grains in the Queen Alexandra Range 99177 CR3 Chondrite

    NASA Astrophysics Data System (ADS)

    Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.

    2015-07-01

    Silicate grains with ~5% 18O enrichment are found in the QUE 99177 meteorite. TEM analysis of one grain indicates an aggregate of pyroxene grains and olivine. The grains could have formed from a fractionated 16O-poor gas reservoir.

  7. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia.

    PubMed

    Theuring, Philipp; Collins, Adrian L; Rode, Michael

    2015-09-01

    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (<10 μm) sediment in the 15 000 km(2) Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal-Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (>0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments.

  8. The role of temporally varying erodibility in hysteresis in fine-grained coastal systems

    NASA Astrophysics Data System (ADS)

    Wiberg, P.; Carr, J. A.

    2013-12-01

    Sediment transport rates are typically expressed as some function of excess shear stress, the difference between the fluid shear stress at the sediment surface and the shear stress needed to initiate transport of the sediment comprising the surface. While a great deal of research has addressed questions related to temporal and spatial variations in the fluid stresses driving transport and deposition, considerably less has focused on temporal and spatial variations in sediment erodibility. Most sediment transport relationships involved a critical shear stress that is at most a function of grain size and density for non-cohesive sediment or a function of depth for cohesive sediment. Such simple characterizations of erodibility are frequently inadequate for representing sediment dynamics in fine-grained coastal and shallow marine environments where a wide range of processes, including consolidation, biofilm production and bioturbation can cause dramatic temporal and spatial (horizontal and vertical) variations in erodibility. For example, flood deposits of mud on the continental shelf can initially be highly erodible, facilitating the formation of wave-supported gravity flows, but quickly (days-weeks) consolidate to the point where they can become relatively resistant to resuspension by large storm waves - well above traditional notions of 'storm wave base'. On the other hand, loss of protection by primary producers - such as a die off of seagrasses or biofilms - can release large quantities of previously stable sediment into a coastal system. In this talk we explore the importance of temporal variations in erodibility on coastal and shallow marine systems in producing path-dependence and hysteresis in fine-grained coastal systems.

  9. Fine-grained sediment storage conditioned by Large Woody Debris in a gravel-bed river

    NASA Astrophysics Data System (ADS)

    Skalak, K. J.; Narinesingh, P.; Pizzuto, J. E.

    2006-05-01

    The purposes of this study are 1) to determine the quantity of mud and sand stored in the channel margins and near-bank regions of South River, a steep gravel-bedded stream in western Virginia, and 2) to understand the geomorphic and hydrologic processes that control the erosion and deposition of these fine-grained deposits. The volume of storage in these deposits is equivalent to about 5-10 percent of the river's annual suspended sediment load. Sediment storage in the near-bank regions is a result of reduced velocity caused by the bank obstructions. Storage occurs in four different geomorphic settings: 1) long pooled sections caused by bedrock or old mill dams, 2) regions downstream of riffles in channel margins with LWD accumulations, 3) bank obstructions usually caused by trees, 4) side channel backwaters where flow separates around islands. Most storage occurs in regions downstream of riffles (approximately 44 percent of the total). Long pooled sections account for roughly 37 percent of the total storage, bank obstructions account for 13 percent, and backwaters account for roughly 6 percent. In approximately 17 km of river, there are 38 separate fine-grained deposits (total volume more than 1600 m3). On average, these deposits are about 35 cm deep, 20 m long, and 4 m wide. They average 30 percent mud, 68 percent sand, and 2 percent gravel. These deposits have been cored and analyzed for Hg, grain size, loss-on-ignition, and bomb radiocarbon. High Hg concentrations in fish tissue are an ongoing problem along South River, further motivating detailed study of these deposits.

  10. Murchison presolar carbon grains of different density fractions: A Raman spectroscopic perspective

    NASA Astrophysics Data System (ADS)

    Wopenka, B.; Xu, Y. C.; Zinner, E.; Amari, S.

    2013-04-01

    Raman analyses are reported of μm-sized areas of 103 individual carbonaceous presolar grains ("graphite grains") from three different density fractions of the Murchison meteorite. Few of the grains (2 or 3 of each density fraction) have Raman spectra typical for non-crystalline sp2-bonded carbon (i.e., "organic carbon") with extremely wide 1st-order and no (or very subdued) 2nd-order peaks, similar to the ones found for terrestrial kerogens. Based on depth profiles of isotopic ratios measured with the NanoSIMS, it is unlikely that such kerogen-type Raman signatures are caused by contamination of the presolar grains with insoluble organic material from the Murchison matrix that stuck to the surfaces of the grains. Rather, the kerogen-type grains are considered to be a new type of presolar carbon grains, which are made up of organic (PAH-like) sp2-bonded carbon. However, most of the other studied presolar carbon grains (95 of 103) have spectra with very narrow 1st-order peaks (called D and G peaks) and very strong 2nd-order peaks typical for inorganic sp2-bonded carbon. Based on their D/G intensity ratios, those grains were grouped into the following Raman types: (fairly well ordered) "graphite" (D/G < 0.5), "disordered graphite" (0.5 < D/G < 1.1), "glassy carbon" (D/G > 1.1), and "unusual sp2-bonded graphitic carbon" (with extremely intense 2nd-order peaks relative to the 1st-order peaks). Grains from the low-density fraction KFA1 (2.05-2.10 g/cm3) have predominantly "cauliflower" morphology and Raman spectra characteristic of either very disordered graphite or "glassy carbon" (i.e., the latter is amorphous from the Raman spectroscopic perspective), whereas most grains from the high-density fraction KFC1 (2.15-2.20 g/cm3) have "onion" morphology and Raman spectra characteristic of well-crystalline graphite. The KFB1 grains with intermediate density (2.10-2.15 g/cm3) are mixed, both in terms of their morphology and their Raman spectra but are closer to KFC1 than to

  11. OSL dating of fine-grained quartz from Holocene Yangtze delta sediments

    NASA Astrophysics Data System (ADS)

    Sugisaki, S.; Buylaert, J. P.; Murray, A. S.; Tada, R.; Zheng, H.; Ke, W.; Saito, K.; Irino, T.; Chao, L.; Shiyi, L.; Uchida, M.

    2014-12-01

    Flood events in the Yangtze River are associated with variation in East Asian Summer Monsoon (EASM) precipitation. Understanding the frequency and scale of the EASM precipitation during the Holocene is a key to understanding the mechanism and cyclicity of floods and droughts. Because about 70% of the annual discharge occurs during the flood season, the Yangtze delta sediments provide a good archive of EASM precipitation. In this study, we investigate the possibility of applying OSL dating to establishing high-resolution chronologies for the Yangtze delta sediment cores YD13-1H and G3. The objectives of this study are: (1) test whether fine grained quartz in present day suspended particle matter (SPM) is fully bleached or reset before deposition, (2) where possible, test quartz fine- and coarse-grain OSL dating against radiocarbon shell ages, (3) interpret the sediment transport processes through the differential bleaching of quartz and feldspar OSL signals. We show that the SPM collected from the surface water column of the Yangtze River during the flood season is well-bleached (offset ~60 years). Fine-grained pro-delta sediments are thus potentially a good dosimeter for OSL dating. OSL ages sediment cores indicate a pronounced change in sedimentation rate at ~6 ka and ~2ka. These events are consistent with what is known of the evolution of the Yangtze catchment and delta. The delta began to build at ~6 ka (Zhao et al., 1979), and human activities increased significantly in the catchment at ~2ka (Chen et al., 1985). It is however surprising that the entire top 9 m of sediment only records these two events. The question of whether significant deposition was limited to 2 ka and 6 ka, or whether the record has been disturbed by erosion/reworking remains. These issues are discussed in terms of the reliability of the quartz OSL ages, the degree of bleaching by comparison with polymineral OSL signals, and the relationship of the OSL ages to the sedimentary record.

  12. Evaluation of an abbreviated impactor for fine particle fraction (FPF) determination of metered dose inhalers (MDI).

    PubMed

    Guo, Changning; Ngo, Diem; Ahadi, Shafiq; Doub, William H

    2013-09-01

    Abbreviated impactors have been developed recently to allow more rapid evaluation of inhalation products as alternates to the eight-stage Andersen Cascade Impactor (ACI) which has been widely used in the pharmaceutical industry for assessing aerodynamic particle size distribution. In this paper, a two-stage abbreviated impactor, Westech Fine Particle Dose Impactor (WFPD), was used to characterize the aerodynamic particle size of metered dose inhaler (MDI) products, and the results were compared with those obtained using the standard eight-stage ACI. Seven commercial MDI products, with different propellants (chlorofluorocarbon/hydrofluoroalkane) and formulation types (suspension/solution, dry/normal/wet), were tested in this study by both WFPD and ACI. Substantially equivalent measures of fine particle fraction were obtained for most of the tested MDI products, but larger coarse particle fraction and extra-fine particle fraction values were measured from WFPD relative to those measured using the ACI. Use of the WFPD also produced more wall loss than the ACI. Therefore, it is recommended that the system suitability be evaluated on a product-by-product basis to establish substantial equivalency before implementing an abbreviated impactor measurement methodology for routine use in inhaler product characterization.

  13. Geochemistry of grain-size fractions of soils from the Taurus-Littrow valley floor

    NASA Technical Reports Server (NTRS)

    Korotev, R. L.

    1976-01-01

    Results are presented for a study in which high-precision instrumental neutron activation analysis was applied to determine the abundances of seven rare-earth and nine other elements in two grain-size fractions (90 to 150 microns and less than 20 microns) of eight soils from the Taurus-Littrow Valley floor and one Apollo 11 bulk-soil fraction with grain sizes of less than 1 mm. Compositional differences between the two size fractions of two valley-floor soils are examined, and mixing of soil components is investigated. It is found that a five-component mixing model describes very adequately the chemical composition of bulk soils with grain sizes of less than 1 mm as mixtures of local Apollo 17 rock types (basalt, anorthositic gabbro, noritic breccia), orange glass, and meteorites, but does not describe well the chemical compositions of the other two size fractions. A ten-component model is used to show that the compositions of those two size fractions can be well represented as mixtures of the five components if the mineralogy and chemical composition of the basalt component are allowed to vary in the size fractions.

  14. Identification of Highly Fractionated (18)O-Rich Silicate Grains in the Queen Alexandra Range 99177 CR3 Chondrite

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.

    2015-01-01

    Carbonaceous chondrites contain a mixture of solar system condensates, presolar grains, and primitive organic matter. The CR3 chondrite QUE 99177 has undergone minimal al-teration [1], exemplified by abundant presolar silicates [2, 3] and anomalous organic matter [4]. Oxygen isotopic imaging studies of this meteorite have focused on finding submicrometer anomalous grains in fine-grained regions of thin sections. Here we present re-sults of an O isotopic survey of larger matrix grains.

  15. Nearshore disposal of fine-grained sediment in a high-energy environment: Santa Cruz Harbor case study

    USGS Publications Warehouse

    Cronin, Katherine; van Ormondt, Maarten; Storlazzi, Curt D.; Presto, Katherine; Tonnon, Pieter K.; Rosati, Julie D.; Wang, Ping; Roberts, Tiffany M.

    2011-01-01

    Current regulations in California prohibit the disposal of more than 20% fine-grained sediment in the coastal zone; this threshold is currently being investigated to determine if this environmental regulation can be improved upon. A field monitoring and numerical modeling experiment took place late 2 009 to determine the fate of fine-grained dredge disposal material from Santa Cruz Harbor, California, U.S.A. A multi-nested, hydrodynamic-sediment transport modeling approach was used to simulate the direction and dispersal of the dredge plume. Result s show that the direction and dispersal of the plume was influenced by the wave  climate, a large proportion of which moved in a easterly direction during wave events. Therefore it is vitally important to accurately simulate the tides, waves, currents, temperature and salinity when modeling the dispersal of the fine-grained dredge plume. 

  16. Age hardening and the potential for superplasticity in a fine-grained Al-Mg-Li-Zr alloys

    SciTech Connect

    Furukawa, Minoru; Berbon, P.B.; Langdon, T.G.; Horita, Zenji; Nemoto, Minoru; Tsenev, N.K.; Valiev, R.Z.

    1998-01-01

    Experiments were conducted to determine the age-hardening characteristics and the mechanical properties of an Al-5.5 pct Mg-2.2 pct Li-0.12 pct Zr alloy processed by equal-channel angular (ECA) pressing to give a very fine grain size of {approximately} 1.2 {micro}m. The results show that peak aging occurs more rapidly when the grain size is very fine, and this effect is interpreted in terms of the higher volume of precipitate-free zones in the fine-grained material. Mechanical testing demonstrates that the ECA-pressed material exhibits high strength and good ductility at room temperature compared to conventional Al alloys containing Li. Elongations of up to {approximately} 550 pct may be achieved at an elevated temperature of 603 K in the ECA-pressed condition, thereby confirming that, in this condition, the alloy may be a suitable candidate material for use in superplastic forming operations.

  17. Memory for pitch in congenital amusia: beyond a fine-grained pitch discrimination problem.

    PubMed

    Williamson, Victoria Jane; Stewart, Lauren

    2010-08-01

    Congenital amusia is a disorder that affects the perception and production of music. While amusia has been associated with deficits in pitch discrimination, several reports suggest that memory deficits also play a role. The present study investigated short-term memory span for pitch-based and verbal information in 14 individuals with amusia and matched controls. Analogous adaptive-tracking procedures were used to generate tone and digit spans using stimuli that exceeded psychophysically measured pitch perception thresholds. Individuals with amusia had significantly smaller tone spans, whereas their digits spans were a similar size to those of controls. An automated operation span task was used to determine working memory capacity. Working memory deficits were seen in only a small subgroup of individuals with amusia. These findings support the existence of a pitch-specific component within short-term memory and suggest that congenital amusia is more than a disorder of fine-grained pitch discrimination.

  18. Enhance the Quality of Crowdsensing for Fine-Grained Urban Environment Monitoring via Data Correlation

    PubMed Central

    Kang, Xu; Liu, Liang; Ma, Huadong

    2017-01-01

    Monitoring the status of urban environments, which provides fundamental information for a city, yields crucial insights into various fields of urban research. Recently, with the popularity of smartphones and vehicles equipped with onboard sensors, a people-centric scheme, namely “crowdsensing”, for city-scale environment monitoring is emerging. This paper proposes a data correlation based crowdsensing approach for fine-grained urban environment monitoring. To demonstrate urban status, we generate sensing images via crowdsensing network, and then enhance the quality of sensing images via data correlation. Specifically, to achieve a higher quality of sensing images, we not only utilize temporal correlation of mobile sensing nodes but also fuse the sensory data with correlated environment data by introducing a collective tensor decomposition approach. Finally, we conduct a series of numerical simulations and a real dataset based case study. The results validate that our approach outperforms the traditional spatial interpolation-based method. PMID:28054968

  19. Products of hydratation in fine grained mixtures MgO - SiO2

    NASA Astrophysics Data System (ADS)

    Szczerba, J.; Prorok, R.; Madej, D.; Sniezek, E.

    2013-12-01

    The aim of this study was to evaluate the influence of time of ageing on phase evolution of paste from MgO-SiO2-H2O phase system. The paste was composed of fine grained sintered magnesia and microsilica in 1:2 molar ratio and water, with water to solid ratio equal 0,5. After preparation the paste was ageing during specified time up to 180 days in temperature 20° C. Phase composition of mixture of MgO and SiO2 with water was studied by XRD, DTA-TGA. The analysis revealed that product of reaction in mixture of MgO, SiO2 and water was a probably poorly crystalline magnesium silicate.

  20. FINE-GRAINED PITCH ACCENT AND BOUNDARY TONE LABELING WITH PARAMETRIC F0 FEATURES

    PubMed Central

    Ananthakrishnan, Sankaranarayanan; Narayanan, Shrikanth

    2009-01-01

    Motivated by linguistic theories of prosodic categoricity, symbolic representations of prosody have recently attracted the attention of speech technologists. Categorical representations such as ToBI not only bear linguistic relevance, but also have the advantage that they can be easily modeled and integrated within applications. Since manual labeling of these categories is time-consuming and expensive, there has been significant interest in automatic prosody labeling. This paper presents a fine-grained ToBI-style prosody labeling system that makes use of features derived from RFC and TILT parameterization of F0 together with a n-gram prosodic language model for 4-way pitch accent labeling and 2-way boundary tone labeling. For this task, our system achieves pitch accent labeling accuracy of 56.4% and boundary tone labeling accuracy of 67.7% on the Boston University Radio News Corpus. PMID:19180228

  1. Ultrasonic-promoted rapid TLP bonding of fine-grained 7034 high strength aluminum alloys.

    PubMed

    Guo, Weibing; Leng, Xuesong; Luan, Tianmin; Yan, Jiuchun; He, Jingshan

    2017-05-01

    High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400°C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60s and holding time of only 3min at 400°C, and the shear strength of joints could reach 223MPa. The joint formation mechanism and effects of ultrasounds were discussed in details.

  2. Fine-grained lower limit of entropic uncertainty in the presence of quantum memory.

    PubMed

    Pramanik, T; Chowdhury, P; Majumdar, A S

    2013-01-11

    The limitation on obtaining precise outcomes of measurements performed on two noncommuting observables of a particle as set by the uncertainty principle in its entropic form can be reduced in the presence of quantum memory. We derive a new entropic uncertainty relation based on fine graining, which leads to an ultimate limit on the precision achievable in measurements performed on two incompatible observables in the presence of quantum memory. We show that our derived uncertainty relation tightens the lower bound set by entropic uncertainty for members of the class of two-qubit states with maximally mixed marginals, while accounting for the recent experimental results using maximally entangled pure states and mixed Bell-diagonal states. An implication of our uncertainty relation on the security of quantum key generation protocols is pointed out.

  3. A Microanalytical (TEM) Study of Fine-grained Chondrule Rims in NWA 5717

    NASA Technical Reports Server (NTRS)

    Bigolski, J. N.; Frank, D. R.; Zolensky, Michael E.; Weisberg, M. K.; Ebel, D. S.; Rahman, Z.

    2013-01-01

    Northwest Africa (NWA) 5717 is a highly primitive ordinary chondrite of petrologic type 3.05 with ubiquitous fine-grained chondrule rims [1, 2]. Rims appear around approximately 60% of chondrules and are comprised of micron-sized mineral and lithic fragments and microchondrules that are embdedded in an FeO-rich submicron groundmass that compositionally resembles fayalitic olivine. Some rim clasts appear overprinted with FeO-rich material, suggesting secondary alteration that postdates rim formation. Here we present a microanalytical (TEM) study of the submicron component (i.e. the groundmass) of the rims in order to determine the crystal structures and compositions of their constituent phases and decipher the accretion and alteration history recorded in rims.

  4. Breakthrough adsorption study of migratory nickel in fine-grained soil.

    PubMed

    Ghosh, S; Mukherjee, S N; Kumar, Sunil; Chakraborty, P; Fan, Maohong

    2007-09-01

    The present study was conducted to evaluate the breakthrough curve for nickel adsorption in fine-grained soil from a nearby ash pond site of a thermal power plant. Nickel was found to be the major polluting solute in the ash sluicing wastewater. The adsorption of nickel by vertical soil column batch test and horizontal migration test was carried out in the laboratory. Field investigation was conducted also, by installing test wells around the ash pond site. Experimental results showed a good adsorptive capacity of soil for nickel ions. The breakthrough curves showed a reasonable fitting with a one-dimensional mathematical model. The breakthrough curves yielded from field test results showed good agreement with a two-dimensional mathematical model.

  5. A unique Critical State two-surface hyperplasticity model for fine-grained particulate media

    NASA Astrophysics Data System (ADS)

    Coombs, W. M.; Crouch, R. S.; Augarde, C. E.

    2013-01-01

    Even mild compression can cause re-arrangement of the internal structure of clay-like geomaterials, whereby clusters of particles rotate and collapse as face-to-face contacts between the constituent mineral platelets increase at the expense of edge-to-face (or edge-to-edge) contacts. The collective action of local particle re-orientation ultimately leads to path-independent isochoric macroscopic deformation under continuous shearing. This asymptotic condition is the governing feature of Critical State elasto-plasticity models. Unlike earlier formulations, the two-surface anisotropic model proposed herein is able to reproduce a unique isotropic Critical State stress envelope which agrees well with test data. Material point predictions are compared against triaxial experimental results and five other existing constitutive models. The hyperplastic formulation is seen to offer a significantly improved descriptor of the anisotropic behaviour of fine-grained particulate materials.

  6. Experimental research on the behavior of the pneumatic transport of fine-grained iron

    NASA Astrophysics Data System (ADS)

    Andrei, V.; Hritac, M.; Constantin, N.; Dobrescu, C.

    2017-01-01

    Mixed injection of fine-grained iron ore and pulverized coal in the furnace, involves determining the behavior of these materials during pneumatic transport in a dense state through the pipe and setting possibilities for adjusting the flow rate of material transported with the corresponding values of the process. Parameters of the pneumatic transport were determined for the main types of iron ore and chalk used in Arcelor Mittal Galati. Outside the intended purpose of injecting iron ore and flux, it was considered also the experimental check of the possibility for injecting ilmenite in the furnace for crucible protection purpose. The possibility of injecting cinder mill into the furnace was also considered. Injecting cinder could be taken into account for the recycling of ferrous waste in the furnace, also as additive for intensifying the combustion process around the tuyeres.

  7. Enhance the Quality of Crowdsensing for Fine-Grained Urban Environment Monitoring via Data Correlation.

    PubMed

    Kang, Xu; Liu, Liang; Ma, Huadong

    2017-01-04

    Monitoring the status of urban environments, which provides fundamental information for a city, yields crucial insights into various fields of urban research. Recently, with the popularity of smartphones and vehicles equipped with onboard sensors, a people-centric scheme, namely "crowdsensing", for city-scale environment monitoring is emerging. This paper proposes a data correlation based crowdsensing approach for fine-grained urban environment monitoring. To demonstrate urban status, we generate sensing images via crowdsensing network, and then enhance the quality of sensing images via data correlation. Specifically, to achieve a higher quality of sensing images, we not only utilize temporal correlation of mobile sensing nodes but also fuse the sensory data with correlated environment data by introducing a collective tensor decomposition approach. Finally, we conduct a series of numerical simulations and a real dataset based case study. The results validate that our approach outperforms the traditional spatial interpolation-based method.

  8. Skeleton versus fine earth: what information is stored in the mobile extracellular soil DNA fraction?

    NASA Astrophysics Data System (ADS)

    Ascher, Judith; Ceccherini, Maria Teresa; Agnelli, Alberto; Corti, Guiseppe; Pietramellara, Giacomo

    2010-05-01

    The soil genome consists of an intracellular and an extracellular fraction. Recently, soil extracellular DNA (eDNA) has been shown to be quantitatively relevant, with a high survival capacity and mobility, playing a crucial role in the gene transfer by transformation, in the formation of bacterial biofilm and as a source of nutrients for soil microorganisms. The eDNA fraction can be discriminated and classified by its interaction with clay minerals, humic acids and Al/Fe oxihydroxides, resulting in differently mobile components. The eDNA extractable in water, classified as DNA free in the extracellular soil environment or adsorbed on soil colloids (eDNAfree/adsorbed), is hypothesized to be the most mobile DNA in soil. Challenging to assess the information stored in this DNA fraction, eDNAfree/adsorbed was recovered from fine earth (< 4 mm) and highly altered rock fragments or skeleton (4-10 mm) of six consecutive horizons (A1-BCb2) of a forest soil profile by washing the two soil fractions with H2O. Quantitative analysis have been conducted in terms of DNA yields (fluorimeter and spectrophotometer), molecular weight and fragment length distribution (gel electrophoresis), and qualitative analysis in terms of the composition and distribution of fungal and bacterial communities (Denaturing Gradient Gel Electrophoresis- fingerprinting). The mobile soil eDNA, extracted from each horizon, was characterised by low molecular weight (< 2 kb) and amounts ranging from 3.96 (±0.179) to 0.17 (±0.023) µg g-1 for the fine earth and from 1.42 (±0.111) to 0.11 (±0.007) µg g-1 for the skeleton. Genetic fingerprinting of eDNA recovered from fine earth and skeleton revealed characteristic fungal and bacterial communities of each horizon, but also similarities among the microbial communities of both soil fractions and horizons. This could be interpreted also as a result of the movement of eDNA along the soil profile and from fine earth to skeleton. The molecular characterization

  9. Effects of grain size distribution on the packing fraction and shear strength of frictionless disk packings.

    PubMed

    Estrada, Nicolas

    2016-12-01

    Using discrete element methods, the effects of the grain size distribution on the density and the shear strength of frictionless disk packings are analyzed. Specifically, two recent findings on the relationship between the system's grain size distribution and its rheology are revisited, and their validity is tested across a broader range of distributions than what has been used in previous studies. First, the effects of the distribution on the solid fraction are explored. It is found that the distribution that produces the densest packing is not the uniform distribution by volume fractions as suggested in a recent publication. In fact, the maximal packing fraction is obtained when the grading curve follows a power law with an exponent close to 0.5 as suggested by Fuller and Thompson in 1907 and 1919 [Trans Am. Soc. Civ. Eng. 59, 1 (1907) and A Treatise on Concrete, Plain and Reinforced (1919), respectively] while studying mixtures of cement and stone aggregates. Second, the effects of the distribution on the shear strength are analyzed. It is confirmed that these systems exhibit a small shear strength, even if composed of frictionless particles as has been shown recently in several works. It is also found that this shear strength is independent of the grain size distribution. This counterintuitive result has previously been shown for the uniform distribution by volume fractions. In this paper, it is shown that this observation keeps true for different shapes of the grain size distribution.

  10. Effects of grain size distribution on the packing fraction and shear strength of frictionless disk packings

    NASA Astrophysics Data System (ADS)

    Estrada, Nicolas

    2016-12-01

    Using discrete element methods, the effects of the grain size distribution on the density and the shear strength of frictionless disk packings are analyzed. Specifically, two recent findings on the relationship between the system's grain size distribution and its rheology are revisited, and their validity is tested across a broader range of distributions than what has been used in previous studies. First, the effects of the distribution on the solid fraction are explored. It is found that the distribution that produces the densest packing is not the uniform distribution by volume fractions as suggested in a recent publication. In fact, the maximal packing fraction is obtained when the grading curve follows a power law with an exponent close to 0.5 as suggested by Fuller and Thompson in 1907 and 1919 [Trans Am. Soc. Civ. Eng. 59, 1 (1907) and A Treatise on Concrete, Plain and Reinforced (1919), respectively] while studying mixtures of cement and stone aggregates. Second, the effects of the distribution on the shear strength are analyzed. It is confirmed that these systems exhibit a small shear strength, even if composed of frictionless particles as has been shown recently in several works. It is also found that this shear strength is independent of the grain size distribution. This counterintuitive result has previously been shown for the uniform distribution by volume fractions. In this paper, it is shown that this observation keeps true for different shapes of the grain size distribution.

  11. Heating during solar nebula formation and Mg isotopic fractionation in precursor grains of CAIs and chondrules

    NASA Technical Reports Server (NTRS)

    Sasaki, S.; Nagahara, H.; Kitagami, K.; Nakagawa, Y.

    1994-01-01

    In some Ca-Al-rich inclusion (CAI) grains, mass-dependent isotopic fractionations of Mg, Si, and O are observed and large Mg isotopic fractionation is interpreted to have been produced by cosmochemical processes such as evaporation and condensation. Mass-dependent Mg isotopic fractionation was found in olivine chondrules of Allende meteorites. Presented is an approximate formula for the temperature of the solar nebula that depends on heliocentric distance and the initial gas distribution. Shock heating during solar nebula formation can cause evaporative fractionation within interstellar grains involved in a gas at the inner zone (a less than 3 AU) of the disk. Alternatively collision of late-accreting gas blobs might cause similar heating if Sigma(sub s) and Sigma are large enough. Since the grain size is small, the solid/gas mass ratio is low and solar (low P(sub O2)), and the ambient gas pressure is low, this heating event could not produce chondrules themselves. Chondrule formation should proceed around the disk midplane after dust grains would grow and sediment to increase the solid/gas ratio there. The heating source there is uncertain, but transient rapid accretion through the disk could release a large amount of heat, which would be observed as FU Orionis events.

  12. Friction and wear performance of boron doped, undoped microcrystalline and fine grained composite diamond films

    NASA Astrophysics Data System (ADS)

    Wang, Xinchang; Wang, Liang; Shen, Bin; Sun, Fanghong

    2015-01-01

    Chemical vapor deposition (CVD) diamond films have attracted more attentions due to their excellent mechanical properties. Whereas as-fabricated traditional diamond films in the previous studies don't have enough adhesion or surface smoothness, which seriously impact their friction and wear performance, and thus limit their applications under extremely harsh conditions. A boron doped, undoped microcrystalline and fine grained composite diamond (BD-UM-FGCD) film is fabricated by a three-step method adopting hot filament CVD (HFCVD) method in the present study, presenting outstanding comprehensive performance, including the good adhesion between the substrate and the underlying boron doped diamond (BDD) layer, the extremely high hardness of the middle undoped microcrystalline diamond (UMCD) layer, as well as the low surface roughness and favorable polished convenience of the surface fine grained diamond (FGD) layer. The friction and wear behavior of this composite film sliding against low-carbon steel and silicon nitride balls are studied on a ball-on-plate rotational friction tester. Besides, its wear rate is further evaluated under a severer condition using an inner-hole polishing apparatus, with low-carbon steel wire as the counterpart. The test results show that the BD-UM-FGCD film performs very small friction coefficient and great friction behavior owing to its high surface smoothness, and meanwhile it also has excellent wear resistance because of the relatively high hardness of the surface FGD film and the extremely high hardness of the middle UMCD film. Moreover, under the industrial conditions for producing low-carbon steel wires, this composite film can sufficiently prolong the working lifetime of the drawing dies and improve their application effects. This research develops a novel composite diamond films owning great comprehensive properties, which have great potentials as protecting coatings on working surfaces of the wear-resistant and anti

  13. Fine-Grained Semantic Categorization across the Abstract and Concrete Domains

    PubMed Central

    Tettamanti, Marco

    2013-01-01

    A consolidated approach to the study of the mental representation of word meanings has consisted in contrasting different domains of knowledge, broadly reflecting the abstract-concrete dichotomy. More fine-grained semantic distinctions have emerged in neuropsychological and cognitive neuroscience work, reflecting semantic category specificity, but almost exclusively within the concrete domain. Theoretical advances, particularly within the area of embodied cognition, have more recently put forward the idea that distributed neural representations tied to the kinds of experience maintained with the concepts' referents might distinguish conceptual meanings with a high degree of specificity, including those within the abstract domain. Here we report the results of two psycholinguistic rating studies incorporating such theoretical advances with two main objectives: first, to provide empirical evidence of fine-grained distinctions within both the abstract and the concrete semantic domains with respect to relevant psycholinguistic dimensions; second, to develop a carefully controlled linguistic stimulus set that may be used for auditory as well as visual neuroimaging studies focusing on the parametrization of the semantic space beyond the abstract-concrete dichotomy. Ninety-six participants rated a set of 210 sentences across pre-selected concrete (mouth, hand, or leg action-related) and abstract (mental state-, emotion-, mathematics-related) categories, with respect either to different semantic domain-related scales (rating study 1), or to concreteness, familiarity, and context availability (rating study 2). Inferential statistics and correspondence analyses highlighted distinguishing semantic and psycholinguistic traits for each of the pre-selected categories, indicating that a simple abstract-concrete dichotomy is not sufficient to account for the entire semantic variability within either domains. PMID:23825625

  14. Fine-grained semantic categorization across the abstract and concrete domains.

    PubMed

    Ghio, Marta; Vaghi, Matilde Maria Serena; Tettamanti, Marco

    2013-01-01

    A consolidated approach to the study of the mental representation of word meanings has consisted in contrasting different domains of knowledge, broadly reflecting the abstract-concrete dichotomy. More fine-grained semantic distinctions have emerged in neuropsychological and cognitive neuroscience work, reflecting semantic category specificity, but almost exclusively within the concrete domain. Theoretical advances, particularly within the area of embodied cognition, have more recently put forward the idea that distributed neural representations tied to the kinds of experience maintained with the concepts' referents might distinguish conceptual meanings with a high degree of specificity, including those within the abstract domain. Here we report the results of two psycholinguistic rating studies incorporating such theoretical advances with two main objectives: first, to provide empirical evidence of fine-grained distinctions within both the abstract and the concrete semantic domains with respect to relevant psycholinguistic dimensions; second, to develop a carefully controlled linguistic stimulus set that may be used for auditory as well as visual neuroimaging studies focusing on the parametrization of the semantic space beyond the abstract-concrete dichotomy. Ninety-six participants rated a set of 210 sentences across pre-selected concrete (mouth, hand, or leg action-related) and abstract (mental state-, emotion-, mathematics-related) categories, with respect either to different semantic domain-related scales (rating study 1), or to concreteness, familiarity, and context availability (rating study 2). Inferential statistics and correspondence analyses highlighted distinguishing semantic and psycholinguistic traits for each of the pre-selected categories, indicating that a simple abstract-concrete dichotomy is not sufficient to account for the entire semantic variability within either domains.

  15. Resistance spot welding of ultra-fine grained steel sheets produced by constrained groove pressing: Optimization and characterization

    SciTech Connect

    Khodabakhshi, F.; Kazeminezhad, M. Kokabi, A.H.

    2012-07-15

    Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel sheets. The ultra-fine grained sheets are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the sheets with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained sheet spot welds have been investigated in the present paper and the welding current and time of resistance spot welding process according to these subjects are optimized. Failure mode and failure load obtained in tensile-shear test, microhardness, X-ray diffraction, transmission electron microscope and scanning electron microscope images have been used to describe the performance of spot welds. The region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. The results show that optimum welding parameters (welding current and welding time) for ultra-fine grained sheets are shifted to lower values with respect to those for as-received specimens. In ultra-fine grained sheets, one new region is formed named recrystallized zone in addition to fusion zone, heat affected zone and base metal. It is shown that microstructures of different zones in ultra-fine grained sheets are finer than those of as-received sheets. - Highlights: Black-Right-Pointing-Pointer Resistance spot welding process is optimized for joining of UFG steel sheets. Black-Right-Pointing-Pointer Optimum welding current and time are decreased with increasing the CGP pass number. Black-Right-Pointing-Pointer Microhardness at BM, HAZ, FZ and recrystallized zone is enhanced due to CGP.

  16. The influence of nano-scale second-phase particles on deformation of fine grained calcite mylonites

    NASA Astrophysics Data System (ADS)

    Herwegh, Marco; Kunze, Karsten

    2002-09-01

    Grey and white carbonate mylonites were collected along thrust planes of the Helvetic Alps. They are characterised by very small grain sizes and non-random grain shape (SPO) and crystallographic preferred orientation (CPO). Presumably they deformed in the field of grain size sensitive flow by recrystallisation accommodated intracrystalline deformation in combination with granular flow. Both mylonites show a similar mean grain size, but in the grey mylonites the grain size range is larger, the grain shapes are more elongate and the dynamically recrystallised calcite grains are more often twinned. Grey mylonites have an oblique CPO, while the CPO in white mylonites is symmetric with respect to the shear plane. Combustion analysis and TEM investigations revealed that grey mylonites contain a higher amount of highly structured kerogens with particle sizes of a few tens of nanometers, which are finely dispersed at the grain boundaries. During deformation of the rock, nano-scale particles reduced the migration velocity of grain boundaries by Zener drag resulting in slower recrystallisation rates of the calcite aggregate. In the grey mylonites, more strain increments were accommodated by individual grains before they became refreshed by dynamic recrystallisation than in white mylonites, where grain boundary migration was less hindered and recrystallisation cycles were faster. Consequently, grey mylonites represent 'deformation' microfabrics while white mylonites are characterised by 'recrystallisation' microfabrics. Field geologists must utilise this different deformation behavior when applying the obliquity in CPO and SPO of the respective mylonites as reliable shear sense indicators.

  17. cuBLASTP: Fine-Grained Parallelization of Protein Sequence Search on CPU+GPU.

    PubMed

    Zhang, Jing; Wang, Hao; Feng, Wu-Chun

    2015-10-12

    BLAST, short for Basic Local Alignment Search Tool, is a ubiquitous tool used in the life sciences for pairwise sequence search. However, with the advent of next-generation sequencing (NGS), whether at the outset or downstream from NGS, the exponential growth of sequence databases is outstripping our ability to analyze the data. While recent studies have utilized the graphics processing unit (GPU) to speedup the BLAST algorithm for searching protein sequences (i.e., BLASTP), these studies use coarse-grained parallelism, where one sequence alignment is mapped to only one thread. Such an approach does not efficiently utilize the capabilities of a GPU, particularly due to the irregularity of BLASTP in both execution paths and memory-access patterns. To address the above shortcomings, we present a fine-grained approach to parallelize BLASTP, where each individual phase of sequence search is mapped to many threads on a GPU. This approach, which we refer to as cuBLASTP, reorders data-access patterns and reduces divergent branches of the most time-consuming phases (i.e., hit detection and ungapped extension). In addition, cuBLASTP optimizes the remaining phases (i.e., gapped extension and alignment with trace back) on a multicore CPU and overlaps their execution with the phases running on the GPU.

  18. Fabrication and thermoelectric properties of fine-grained TiNiSn compounds

    SciTech Connect

    Zou Minmin; Li Jingfeng; Du Bing; Liu Dawei; Kita, Takuji

    2009-11-15

    Nearly single-phased TiNiSn half-Heusler compound thermoelectric materials were synthesized by combining mechanical alloying (MA) and spark plasma sintering (SPS) in order to reduce its thermal conductivity by refining the grain sizes. Although TiNiSn compound powders were not synthesized directly via MA, dense bulk samples of TiNiSn compound were obtained by the subsequent SPS treatment. It was found that an excessive Ti addition relative to the TiNiSn stoichiometry is effective in increasing the phase purity of TiNiSn half-Heusler phase in the bulk samples, by compensating for the Ti loss caused by the oxidation of Ti powders and MA processing. The maximum power factor value obtained in the Ti-compensated sample is 1720 muW m{sup -1} K{sup -2} at 685 K. A relatively high ZT value of 0.32 is achieved at 785 K for the present undoped TiNiSn compound polycrystals. - Graphical abstract: Nearly single-phased TiNiSn-based half-Heusler compound polycrystalline materials with fine grains were fabricated by combining mechanical alloying (MA) and spark plasma sintering (SPS). A high ZT value for undoped TiNiSn was obtained because of the reduced thermal conductivity.

  19. A Shocked Presolar Crystalline Olivine Within the Fine Grained Rim of an Allan Hills A77307 Chondrule: A Tracer for Parent Body Processes?

    NASA Astrophysics Data System (ADS)

    Stojic, A. N.; Leitner, J.; Hoppe, P.; Brenker, F. E.

    2016-08-01

    We report on a presolar crystalline olivine grain characterised by ATEM in its hosting fine grained rim, a large surrounding electron transparent area enables insights into alteration processes linked to parent body and terrestrial processing.

  20. Fine-grained policy control in U.S. Army Research Laboratory (ARL) multimodal signatures database

    NASA Astrophysics Data System (ADS)

    Bennett, Kelly; Grueneberg, Keith; Wood, David; Calo, Seraphin

    2014-06-01

    The U.S. Army Research Laboratory (ARL) Multimodal Signatures Database (MMSDB) consists of a number of colocated relational databases representing a collection of data from various sensors. Role-based access to this data is granted to external organizations such as DoD contractors and other government agencies through a client Web portal. In the current MMSDB system, access control is only at the database and firewall level. In order to offer finer grained security, changes to existing user profile schemas and authentication mechanisms are usually needed. In this paper, we describe a software middleware architecture and implementation that allows fine-grained access control to the MMSDB at a dataset, table, and row level. Result sets from MMSDB queries issued in the client portal are filtered with the use of a policy enforcement proxy, with minimal changes to the existing client software and database. Before resulting data is returned to the client, policies are evaluated to determine if the user or role is authorized to access the data. Policies can be authored to filter data at the row, table or column level of a result set. The system uses various technologies developed in the International Technology Alliance in Network and Information Science (ITA) for policy-controlled information sharing and dissemination1. Use of the Policy Management Library provides a mechanism for the management and evaluation of policies to support finer grained access to the data in the MMSDB system. The GaianDB is a policy-enabled, federated database that acts as a proxy between the client application and the MMSDB system.

  1. Characterisation of fine-grained tailings from a marble processing plant and their acute effects on the copepod Calanus finmarchicus.

    PubMed

    Farkas, Julia; Altin, Dag; Hammer, Karen M; Hellstrøm, Kaja C; Booth, Andy M; Hansen, Bjørn Henrik

    2017-02-01

    Submarine tailing disposal (STD) of mining waste is practiced as an alternative to land fill disposal in several countries. Knowledge regarding the environmental implications of STD on fjord and other marine ecosystems, including the pelagic environment, is scarce. In this study, we characterised the particle shape, size and metal content of the fine-grained fraction of tailings (FGT) from a Norwegian marble processing plant and investigated their acute toxicity and impact on feeding rate in adult Calanus finmarchicus. Initial tailing dispersions with a concentration of 1 mg mL(-1) contained approximately 72 million particles, with 62% of particles between 0.6 and 1 μm in size. After a sedimentation time of 1 h, 69% of the particles between 0.6 and 5 μm remained dispersed, decreasing to 22% after 6 h. When subjected to low energy turbulence in exposure experiments, the formation of fragile agglomerates was observed. The FGT contained Al, Mn, Fe and Ni, with no detectable dissolution occurring during the 48 h exposure period. Acute exposure (up to 5 g L(-1)) to FGT caused no mortality in C. finmarchicus. Similarly, feeding rates determined during a 40 h depuration period, were not significantly impacted. However, surface attachment and uptake of FGT into the digestive tract of the copepods was observed. This indicates that, whilst marble FGT are not acutely toxic to copepods, chronic effects such as impacts on organism's energy budgets could occur, highlighting the need for further research on potential sublethal effects in organisms exposed to fine inorganic particles.

  2. Fine-grained channel margin (FGCM) deposits conditioned by Large Woody Debris (LWD) in a gravel-bed river

    NASA Astrophysics Data System (ADS)

    Skalak, K. J.; Pizzuto, J. E.

    2006-12-01

    The purpose of this research is to examine the origin, occurrence, persistence, residence time and general significance of fine-grained channel margin storage in South River, a steep gravel-bedded stream in western Virginia. Fine-grained channel margin (FGCM) deposits in this study refers to specific in-channel deposits of mud and sand. These deposits occur primarily in the margins and near-banks regions of the channel. Fine- grained sediment storage in the near-bank regions is a result of reduced velocity caused by the bank obstructions. Nearly all of these obstructions consist of LWD accumulations in the channel. Storage occurs in four different geomorphic settings: 1) long pooled sections caused by bedrock or old mill dams, 2) the upstream ends of pools in channel margins with LWD accumulations, 3) bank obstructions usually caused by trees, 4) side channel backwaters where flow separates around islands. In approximately 38 km of river, there is 3000 m3 of fine-grained sediment stored in these features. The channel stores approximately 15 percent its total annual suspended load as fine-grained channel margin deposits. Consequently, these features represent a significant component of an annual sediment budget for this river. On average, the FGCM deposits are about 35 cm deep, 20 m long, and 4 m wide. They average 30 percent mud, 68 percent sand, and 2 percent gravel. These deposits have been cored and analyzed for Hg, grain size, loss-on-ignition, and bomb radiocarbon. Results from bomb radiocarbon analysis indicate that these features have an average age of 13 years. High Hg concentrations in fish tissue are an ongoing problem along South River, further motivating detailed study of these deposits.

  3. Fine-grained sediment spatial distribution on the basis of a geostatistical analysis: Example of the eastern Bay of the Seine (France)

    NASA Astrophysics Data System (ADS)

    Méar, Y.; Poizot, E.; Murat, A.; Lesueur, P.; Thomas, M.

    2006-12-01

    The eastern Bay of the Seine (English Channel) was the subject in 1991 of a sampling survey of superficial sediments. Geostatistic tools were used to examine the complexity of the spatial distribution of the fine-grained fraction (<50 μm). A central depocentre of fine sediments (i.e. content up to 50%) oriented in a NW-SE direction in a muddy coastal strip, in a very high energy hydrodynamical situation due to storm swells and its megatidal setting, is for the first time recognised and discussed. Within this sedimentary unit, the distribution of the fine fraction is very heterogeneous, with mud patches of less than 4000 m diameter; the boundary between these mud patches and their substratum is very sharp. The distribution of this fine fraction appears to be controlled by an anticyclonic eddy located off the Pays de Caux. Under the influence of this, the suspended material expelled from the Seine estuary moves along the coast and swings off Antifer harbour, towards the NW. It is trapped within this eddy because of the settling of suspended particulate matter. Both at a general scale and a local scale the morphology (whether inherited or due to modern processes) has a strong influence on the spatial distribution of the fine fraction. At the general scale, the basin-like shape of the area facilitates the silting, and the presence of the submarine dunes, called "Ridins d'Antifer", clearly determines the northern limit of the muddy zone. At a local scale, the same influence is obvious: paleovalleys trap the fine sediments, whereas isolated sand dunes and ripples limit the silting. This duality of role of the morphology is therefore one of the reasons why the muddy surface is extremely heterogeneous spatially. The presence of an important population of suspension feeding echinoderm, the brittle-star Ophiothrix fragilis Abildgaard, has led to a local increase in the silting, and to the modification of the physicochemical and sedimentological parameters. A complex

  4. Testing the MODIS Satellite Retrieval of Aerosol Fine-Mode Fraction

    NASA Technical Reports Server (NTRS)

    Anderson, Theodore L.; Wu, Yonghua; Chu, D. Allen; Schmid, Beat; Redemann, Jens; Dubovik, Oleg

    2005-01-01

    Satellite retrievals of the fine-mode fraction (FMF) of midvisible aerosol optical depth, tau, are potentially valuable for constraining chemical transport models and for assessing the global distribution of anthropogenic aerosols. Here we compare satellite retrievals of FMF from the Moderate Resolution Imaging Spectroradiometer (MODIS) to suborbital data on the submicrometer fraction (SMF) of tau. SMF is a closely related parameter that is directly measurable by in situ techniques. The primary suborbital method uses in situ profiling of SMF combined with airborne Sun photometry both to validate the in situ estimate of ambient extinction and to take into account the aerosol above the highest flight level. This method is independent of the satellite retrieval and has well-known accuracy but entails considerable logistical and technical difficulties. An alternate method uses Sun photometer measurements near the surface and an empirical relation between SMF and the Angstrom exponent, A, a measure of the wavelength dependence of optical depth or extinction. Eleven primary and fifteen alternate comparisons are examined involving varying mixtures of dust, sea salt, and pollution in the vicinity of Korea and Japan. MODIS ocean retrievals of FMF are shown to be systematically higher than suborbital estimates of SMF by about 0.2. The most significant cause of this discrepancy involves the relationship between 5 and fine-mode partitioning; in situ measurements indicate a systematically different relationship from what is assumed in the satellite retrievals. Based on these findings, we recommend: (1) satellite programs should concentrate on retrieving and validating since an excellent validation program is in place for doing this, and (2) suborbital measurements should be used to derive relationships between A and fine-mode partitioning to allow interpretation of the satellite data in terms of fine-mode aerosol optical depth.

  5. The role of fine material and grain size distribution on excess pore pressure dissipation and particle support mechanisms in granular deposits based in large-scale physical experiments

    NASA Astrophysics Data System (ADS)

    Palucis, M. C.; Kaitna, R.; Tewoldebrhan, B.; Hill, K. M.; Dietrich, W. E.

    2011-12-01

    The dominant mechanisms behind sustained mobilization in granular debris flows are poorly understood, and experiments are needed to determine the conditions under which the fluid can fully support the coarse fraction. However, field-scale studies are difficult to instrument and constrain and laboratory studies suffer from scaling issues. A 4-m rotating drum located at UC Berkeley's Richmond Field Station allowed us to perform reproducible experiments with materials similar to those in the field to explore mechanisms relevant to slow pore fluid pressure dissipation. Specifically, we performed a series of experiments to assess the role of fines and grain size distribution on the rate of pore fluid pressure dissipation upon deposition of a granular mass. For each experiment we kept the total mass of the gravel particles constant and varied the amount of fines (from no fines to amounts found in an actual debris flow deposit) and the gravel particle size distribution (from a single grain size to a range found in natural flows). We first rotated each mixture in the drum, during which we monitored fluid pressures at the base of the flows (near the wall of the drum and at the center). Then we stopped the drum and continued to monitor the fluid pressures. Immediately upon stopping, the pore fluid pressure was nearly hydrostatic for the gravel-water flows, and any elevated pore pressure quickly dissipated. On the other hand, the mixtures with fines contents close to those found in actual debris flows had elevated pore pressures indicating they were almost fully liquefied. Furthermore, the rate of pore pressure dissipation was an order of magnitude slower than when no fines were present; the grain size distribution of the coarse fraction did not strongly influence the dissipation rates in either case. We also placed a cobble upon a fines-rich mixture after cessation of motion above the center pressure sensor, and observed that the pore fluid pressure rose instantly, bearing

  6. Fine Grain Assessment of Students' Mathematical Understanding: Participatory and Anticipatory Stages in Learning a New Mathematical Conception

    ERIC Educational Resources Information Center

    Tzur, Ron

    2007-01-01

    This study addressed a twofold problem--the soundness of a theoretical stage-distinction regarding the process of constructing a new (to the learner) mathematical conception and how such distinction contributes to fine grain assessment of students' mathematical understandings. As a context for the study served the difficult-to-grasp concept of…

  7. Incorporation of Fine-Grained Sediment Erodibility Measurements into Sediment Transport Modeling, Capitol Lake, Washington

    USGS Publications Warehouse

    Stevens, Andrew W.; Gelfenbaum, Guy; Elias, Edwin; Jones, Craig

    2008-01-01

    Capitol Lake was created in 1951 with the construction of a concrete dam and control gate that prevented salt-water intrusion into the newly formed lake and regulated flow of the Deschutes River into southern Puget Sound. Physical processes associated with the former tidally dominated estuary were altered, and the dam structure itself likely caused an increase in retention of sediment flowing into the lake from the Deschutes River. Several efforts to manage sediment accumulation in the lake, including dredging and the construction of sediment traps upriver, failed to stop the lake from filling with sediment. The Deschutes Estuary Feasibility Study (DEFS) was carried out to evaluate the possibility of removing the dam and restoring estuarine processes as an alternative ongoing lake management. An important component of DEFS was the creation of a hydrodynamic and sediment transport model of the restored Deschutes Estuary. Results from model simulations indicated that estuarine processes would be restored under each of four restoration alternatives, and that over time, the restored estuary would have morphological features similar to the predam estuary. The model also predicted that after dam-removal, a large portion of the sediment eroded from the lake bottom would be deposited near the Port of Olympia and a marina located in lower Budd Inlet seaward of the present dam. The volume of sediment transported downstream was a critical piece of information that managers needed to estimate the total cost of the proposed restoration project. However, the ability of the model to predict the magnitude of sediment transport in general and, in particular, the volume of sediment deposition in the port and marina was limited by a lack of information on the erodibility of fine-grained sediments in Capitol Lake. Cores at several sites throughout Capitol Lake were collected between October 31 and November 1, 2007. The erodibility of sediments in the cores was later determined in the

  8. Jupiter's Satellite Europa: Evidence for an Extremely Fine-Grained, High Porosity Surface

    NASA Astrophysics Data System (ADS)

    Nelson, Robert M.; Boryta, Mark D.; Hapke, Bruce W.; Manatt, Ken S.; Nebedum, Adaeze; Kroner, Desiree; Shkuratov, Yuriy; Psarev, Vladimir; Smythe, William D.

    2015-11-01

    We have measured the polarization phase curves of highly reflective, fine-grained, particulate materials that simulate Europa’s predominately water ice regolith. Our laboratory measurements exhibit polarization phase curves that are remarkably similar to results reported by experienced astronomers (Rosenbush et al., 1997, 2015). Our previous reflectance phase curve measurements of the same materials were in agreement with the same astronomical observers. In addition, we found that these materials exhibit an increase in circular polarization ratio with decreasing phase angle. This is consistent with coherent backscattering (CB) of photons in the regolith (Nelson et al., 2000, 2002). Shkuratov et al. (2002) report that the polarization properties of these particulate media are also consistent with the CB enhancement process (Shkuratov, 1989; Muinonen, 1990).We have reconfigured a goniometric photopolarimeter (Nelson et al., 2000, 2002) to undertake measurements of the polarization phase curves of these particulate materials. Our reconfiguration applies the Helmholtz Reciprocity Principle (Hapke, 2012, p264) - i.e. we present our samples with linearly polarized light and measure the intensity of the reflected component. These laboratory measurements are physically equivalent to the astronomical polarization measurements. We report here the polarization phase curves of high albedo Aluminium Oxide particulates of size 0.1fine-grained, with remarkably high porosity

  9. SWeRF--A method for estimating the relevant fine particle fraction in bulk materials for classification and labelling purposes.

    PubMed

    Pensis, Ingeborg; Luetzenkirchen, Frank; Friede, Bernd

    2014-05-01

    In accordance with the European regulation for classification, labelling and packaging of substances and mixtures (CLP) as well as the criteria as set out in the Globally Harmonized System (GHS), fine fraction of crystalline silica (CS) has been classified as a specific target organ toxicity, the specific organ in this case being the lung. Generic cut-off values for products containing a fine fraction of CS trigger the need for a method for the quantification of the fine fraction of CS in bulk materials. This article describes the so-called SWeRF method, the size-weighted relevant fine fraction. The SWeRF method combines the particle size distribution of a powder with probability factors from the EN 481 standard and allows the relevant fine fraction of a material to be calculated. The SWeRF method has been validated with a number of industrial minerals. This will enable manufacturers and blenders to apply the CLP and GHS criteria for the classification of mineral products containing RCS a fine fraction of CS.

  10. SWeRF—A Method for Estimating the Relevant Fine Particle Fraction in Bulk Materials for Classification and Labelling Purposes

    PubMed Central

    2014-01-01

    In accordance with the European regulation for classification, labelling and packaging of substances and mixtures (CLP) as well as the criteria as set out in the Globally Harmonized System (GHS), fine fraction of crystalline silica (CS) has been classified as a specific target organ toxicity, the specific organ in this case being the lung. Generic cut-off values for products containing a fine fraction of CS trigger the need for a method for the quantification of the fine fraction of CS in bulk materials. This article describes the so-called SWeRF method, the size-weighted relevant fine fraction. The SWeRF method combines the particle size distribution of a powder with probability factors from the EN 481 standard and allows the relevant fine fraction of a material to be calculated. The SWeRF method has been validated with a number of industrial minerals. This will enable manufacturers and blenders to apply the CLP and GHS criteria for the classification of mineral products containing RCS a fine fraction of CS. PMID:24389081

  11. Fine-grained rutile in the Gulf of Maine - diagenetic origin, source rocks, and sedimentary environment of deposition

    USGS Publications Warehouse

    Valentine, P.C.; Commeau, J.A.

    1990-01-01

    The Gulf of Maine, an embayment of the New England margin, is floored by shallow, glacially scoured basins that are partly filled with late Pleistocene and Holocene silt and clay containing 0.7 to 1.0 wt percent TiO2 chiefly in the form of silt-size rutile. Much of the rutile in the Gulf of Maine mud probably formed diagenetically in poorly cemented Carboniferous and Triassic coarse-grained sedimentary rocks of Nova Scotia and New Brunswick after the dissolution of titanium-rich detrital minerals (ilmenite, ilmenomagnetite). The diagenesis of rutile in coarse sedimentary rocks (especially arkose and graywacke) followed by erosion, segregation, and deposition (and including recycling of fine-grained rutile from shales) can serve as a model for predicting and prospecting for unconsolidated deposits of fine-grained TiO2. -from Authors

  12. Groundwater flow, velocity, and age in a thick, fine-grained till unit in southeastern Wisconsin

    NASA Astrophysics Data System (ADS)

    Simpkins, W. W.; Bradbury, K. R.

    1992-03-01

    Piezometer nests were installed at study sites in each of five north-south-trending end moraines of the late Pleistocene Oak Creek Formation in southeastern Wisconsin. The formation is composed primarily of a fine-grained glacial diamicton (till) and laterally continuous and discontinuous, coarse-grained lake and meltwater stream sediment. It overlies the Silurian dolomite aquifer, which is a source of drinking water to rural areas. The average vertical linear velocity and age of ground water in the Oak Creek Formation were estimated by three methods: Darcy's Law, environmental isotopes including 3H, δ2H, δ18O, and 14C (dissolved inorganic carbon), and solute transport modeling of 18O. The F-1 and Metro sites in the Tinley moraine showed excellent agreement among the three estimates of vertical velocity and showed the lowest velocity values (0.3-0.5 cm year -1 downward), which suggests that diffusion controls vertical mass transport at these sites. Although the extrapolated maximum age of ground water is 35 000 years, ground water below 75 m at these sites is probably not older than 15 000 years, which is the maximum age of the formation. Estimates of velocity showed less agreement at study sites in the Lake Border moraine system to the east and ranged from about 0.2 to 20.7 cm year -1; maximum groundwater age could range from 213 to 6000 years. Higher and more variable velocities, perhaps owing to thinner and more heterogeneous sediment in these areas, suggest that diffusion may not dominate vertical mass transport. Heterogeneity and fractures may also promote the development of groundwater flow systems dominated by lateral flow. Because of the uncertainty about the nature of groundwater flow, velocity, and age in the formation east of the Tinley moraine, future waste-disposal activity in southeastern Wisconsin should be confined to the thickest parts of the Tinley moraine near the present F-1 and Metro sites.

  13. Groundwater flow, velocity, and age in a thick, fine-grained till unit in southeastern Wisconsin

    USGS Publications Warehouse

    Simpkins, W.W.; Bradbury, K.R.

    1992-01-01

    Piezometer nests were installed at study sites in each of five north-south-trending end moraines of the late Pleistocene Oak Creek Formation in southeastern Wisconsin. The formation is composed primarily of a fine-grained glacial diamicton (till) and laterally continuous and discontinuous, coarse-grained lake and meltwater stream sediment. It overlies the Silurian dolomite aquifer, which is a source of drinking water to rural areas. The average vertical linear velocity and age of ground water in the Oak Creek Formation were estimated by three methods: Darcy's Law, environmental isotopes including 3H, ??2H, ??18O, and 14C (dissolved inorganic carbon), and solute transport modeling of 18O. The F-1 and Metro sites in the Tinley moraine showed excellent agreement among the three estimates of vertical velocity and showed the lowest velocity values (0.3-0.5 cm year-1 downward), which suggests that diffusion controls vertical mass transport at these sites. Although the extrapolated maximum age of ground water is 35 000 years, ground water below 75 m at these sites is probably not older than 15 000 years, which is the maximum age of the formation. Estimates of velocity showed less agreement at study sites in the Lake Border moraine system to the east and ranged from about 0.2 to 20.7 cm year-1; maximum groundwater age could range from 213 to 6000 years. Higher and more variable velocities, perhaps owing to thinner and more heterogeneous sediment in these areas, suggest that diffusion may not dominate vertical mass transport. Heterogeneity and fractures may also promote the development of groundwater flow systems dominated by lateral flow. Because of the uncertainty about the nature of groundwater flow, velocity, and age in the formation east of the Tinley moraine, future waste-disposal activity in southeastern Wisconsin should be confined to the thickest parts of the Tinley moraine near the present F-1 and Metro sites. ?? 1992.

  14. Geochemical and petrographical characterization of fine-grained carbonate particles along proximal to distal transects

    NASA Astrophysics Data System (ADS)

    Turpin, Mélanie; Emmanuel, Laurent; Immenhauser, Adrian; Renard, Maurice

    2012-12-01

    The origin of carbonate ooze particles is often poorly understood. This is due to their polygenic origin and potential post-depositional alteration. Here, the outcome of a physical separation study with regard to different component classes of micritic carbonates is shown. The focus is on grain size and morphology, mineralogy and isotope signatures. Two contrasting proximal-to-distal transects were investigated: (1) the Miocene leeward margin of Great Bahama Bank (ODP Leg 166) and (2) the transition between the Maiella platform and the Umbria-Marche basin in central Italy near the Cenomanian-Turonian boundary. In both case settings, carbonate particles of biogenic origin include at least three groups of organisms: (i) planktonic foraminifera, (ii) calcareous nannofossils and (iii) fragments of unspecified neritic skeletal material. Two further particle types lack diagnostic structures, and based on particle size and mineralogy, are here referred to as (iv) macroparticles (5-20 μm, mainly xenomorphic) and (v) microparticles (< 12 μm, mainly automorphic to sub-automorphic). Macro- and microparticles represent 50 to 80% of the carbonate phase in slope and toe-of-slope domains and share characteristic carbon and oxygen isotope signatures. Macro- and microparticles are considered shallow-water precipitation products subsequently exported into the slope and toe-of-slope domains. Macroparticles are probably related to the fragmentation of neritic skeletal components while microparticles point to inorganic and/or bioinduced precipitation in the water column. In some cases, macro- and microparticles may have an early diagenetic origin. The identification of the origin of fine-grained particles allows for a quantitative assessment of exported, in situ and diagenetic carbonate materials in periplatform environments. The data shown here represent an important step towards a more complete characterization of carbonate ooze and micrite.

  15. Sorption of organic carbon compounds to the fine fraction of surface and Subsurface Soils

    SciTech Connect

    Jagadamma, Sindhu; Mayes, Melanie; Zinn, Yuri; Gisladottir, Gudrun; Ann, Russell

    2014-01-01

    Dissolved organic carbon (DOC) transported from the soil surface is stabilized in deeper soil profiles by physicochemical sorption processes. However, it is unclear how different forms of organic carbon (OC) compounds common in soil organic matter interact with soil minerals in the surface (A) and subsurface (B) horizons. We added four compounds (glucose, starch, cinnamic acid and stearic acid) to the silt- and clay-sized fraction (fine fraction) of A and B horizons of eight soils from varying climates (3 temperate, 3 tropical, 1 arctic and 1 sub-arctic). Equilibriumbatch experiments were conducted using 0 to 100 mg C L 1 of 14C-labeled compounds for 8 h. Sorption parameters (maximum sorption capacity, Qmax and binding coefficient, k) calculated by fitting sorption data to the Langmuir equation showed that Qmax of A and B horizons was very similar for all compounds. Both Qmax and k values were related to sorbate properties, with Qmax being lowest for glucose (20 500 mg kg 1), highest for stearic acid (20,000 200,000 mg kg 1), and intermediate for both cinnamic acid (200 4000 mg kg 1) and starch (400 6000 mg kg 1). Simple linear regression analysis revealed that physicochemical properties of the sorbents influenced the Qmax of cinnamic acid and stearic acid, but not glucose and starch. The sorbent properties did not show predictive ability for binding coefficient k. By using the fine fraction as sorbent, we found that the mineral fractions of A horizons are equally reactive as the B horizons irrespective of soil organic carbon content.

  16. Determination of degradation rates of organic substances in the unsaturated soil zone depending on the grain size fractions of various soil types

    NASA Astrophysics Data System (ADS)

    Fichtner, Thomas; Stefan, Catalin; Goersmeyer, Nora

    2015-04-01

    Rate and extent of the biological degradation of organic substances during transport through the unsaturated soil zone is decisively influenced by the chemical and physical properties of the pollutants such as water solubility, toxicity and molecular structure. Furthermore microbial degradation processes are also influenced by soil-specific properties. An important parameter is the soil grain size distribution on which the pore volume and the pore size depends. Changes lead to changes in air and water circulation as well as preferred flow paths. Transport capacity of water inclusive nutrients is lower in existing bad-drainable fine pores in soils with small grain size fractions than in well-drainable coarse pores in a soil with bigger grain size fractions. Because fine pores are saturated with water for a longer time than the coarse pores and oxygen diffusion in water is ten thousand times slower than in air, oxygen is replenished much slower in soils with small grain size fractions. As a result life and growth conditions of the microorganisms are negatively affected. This leads to less biological activity, restricted degradation/mineralization of pollutants or altered microbial processes. The aim of conducted laboratory column experiments was to study the correlation between the grain size fractions respectively pore sizes, the oxygen content and the biodegradation rate of infiltrated organic substances. Therefore two columns (active + sterile control) were filled with different grain size fractions (0,063-0,125 mm, 0,2-0,63 mm and 1-2 mm) of soils. The sterile soil was inoculated with a defined amount of a special bacteria culture (sphingobium yanoikuae). A solution with organic substances glucose, oxalic acid, sinaphylic alcohol and nutrients was infiltrated from the top in intervals. The degradation of organic substances was controlled by the measurement of dissolved organic carbon in the in- and outflow of the column. The control of different pore volumes

  17. Shock-induced fine-grained recrystallization of olivine - Evidence against subsolidus reduction of Fe/2+/

    NASA Technical Reports Server (NTRS)

    Ahrens, T. J.; Tsay, F.-D.; Live, D. H.

    1976-01-01

    Electron spin resonance (ESR) studies have been carried out on three single grains of terrestrial olivine (Fo90) shock loaded along the 010 line to peak pressures of 280, 330, and 440 kbar. The results indicate that neither metallic Fe similar to that observed in returned lunar soils nor paramagnetic Fe(3+) caused by oxidation of Fe(2+) has been produced in these shock experiments. Trace amounts of Mn (2+) have been detected in both shocked and unshocked olivine. The ESR signals of Mn(2+) show spectral features which are found to correlate with the degree of shock-induced recrystallization observed petrographically. The increasing mass fraction of recrystallized olivine correlates with increasing shock pressures. This phenomenon is modelled assuming it results from the progressive effect of the shock-induced transformation of the olivine to a yet unknown high-pressure phase and its subsequent reversion to the low-pressure olivine phase. The mass fraction of recrystallized material is predicted to be nearly linear with shock pressure.

  18. Aluminium recovery vs. hydrogen production as resource recovery options for fine MSWI bottom ash fraction.

    PubMed

    Biganzoli, Laura; Ilyas, Aamir; Praagh, Martijn van; Persson, Kenneth M; Grosso, Mario

    2013-05-01

    Waste incineration bottom ash fine fraction contains a significant amount of aluminium, but previous works have shown that current recovery options based on standard on-step Eddy Current Separation (ECS) have limited efficiency. In this paper, we evaluated the improvement in the efficiency of ECS by using an additional step of crushing and sieving. The efficiency of metallic Al recovery was quantified by measuring hydrogen gas production. The ash samples were also tested for total aluminium content with X-ray fluorescence spectroscopy (XRF). As an alternative to material recovery, we also investigated the possibility to convert residual metallic Al into useful energy, promoting H2 gas production by reacting metallic Al with water at high pH. The results show that the total aluminium concentration in the <4 mm bottom ash fraction is on average 8% of the weight of the dry ash, with less than 15% of it being present in the metallic form. Of this latter, only 21% can be potentially recovered with ECS combined with crushing and sieving stages and subsequently recycled. For hydrogen production, using 10MNaOH at 1L/S ratio results in the release of 6-11l of H2 gas for each kilogram of fine dry ash, equivalent to an energy potential of 118 kJ.

  19. Production of pyroxene ceramics from the fine fraction of incinerator bottom ash.

    PubMed

    Bourtsalas, A; Vandeperre, L J; Grimes, S M; Themelis, N; Cheeseman, C R

    2015-11-01

    Incinerator bottom ash (IBA) is normally processed to extract metals and the coarse mineral fraction is used as secondary aggregate. This leaves significant quantities of fine material, typically less than 4mm, that is problematic as reuse options are limited. This work demonstrates that fine IBA can be mixed with glass and transformed by milling, calcining, pressing and sintering into high density ceramics. The addition of glass aids liquid phase sintering, milling increases sintering reactivity and calcining reduces volatile loss during firing. Calcining also changes the crystalline phases present from quartz (SiO2), calcite (CaCO3), gehlenite (Ca2Al2SiO7) and hematite (Fe2O3) to diopside (CaMgSi2O6), clinoenstatite (MgSiO3) and andradite (Ca3Fe2Si3O12). Calcined powders fired at 1080°C have high green density, low shrinkage (<7%) and produce dense (2.78 g/cm(3)) ceramics that have negligible water absorption. The transformation of the problematic fraction of IBA into a raw material suitable for the manufacture of ceramic tiles for use in urban paving and other applications is demonstrated.

  20. Effect of pressure on rheology of fine-grained forsterite aggregate

    NASA Astrophysics Data System (ADS)

    Nishihara, Y.; Ohuchi, T.; Kawazoe, T.; Spengler, D.; Tasaka, M.; Hiraga, T.; Kikegawa, T.; Suzuki, A.; Ohtani, E.

    2011-12-01

    Under the conditions of the Earth's mantle, both diffusion creep and dislocation creep can be the dominant deformation mechanism depending on physical and chemical environments. These two mechanisms are quite different in terms of stress dependence of viscosity and development of lattice-preferred orientation. Thus it is important to understand the dominant deformation mechanism in the mantle. Previous studies on rheology of olivine under high-pressure (>3 GPa) mostly focused on dislocation creep (e.g. Kawazoe et al., 2009; Durham et al., 2009). Knowledge of diffusion creep (and other grain-size sensitive creep, e.g. grain-boundary-sliding related creep) of olivine under deep upper mantle condition (>100 km) has been quite limited. In order to clarify the dominant deformation mechanism in the upper mantle, we have conducted deformation experiments at high-pressure and high-temperature using fine-grained forsterite aggregate. Experiments were carried out using a D-DIA apparatus "D-CAP (deformation cubic-anvil press)" installed at NE7 beamline, PF-AR, High Energy Accelerator Research Institute, Tsukuba, Japan (Shiraishi et al., 2011). The samples are sintered aggregate of 90%forsterite + 10%enstatite with average grain size of ~1 μm. High-pressure was generated by MA6-6 assembly using cubic (Mg,Co)O pressure medium and WC anvils with 5 mm truncation edge length (e.g. Kawazoe et al., 2010). High-temperature was generated using graphite furnace and was monitored by WRe thermocouple. Deformation experiments were conducted at pressure of 3.0-5.3 GPa, temperature of 1473-1573 K, and uniaxial strain rate of 9 × 10-6-2 × 10-4 s-1. Sample stress was measured by two-dimensional X-ray diffraction using monochromatized synchrotron X-ray (~50 keV) and imaging plate detector. Sample strain was measured by X-ray radiography. H2O concentration in starting material and recovered samples was determined based on FTIR analyses (Paterson, 1982). Steady state flow stress was

  1. In vitro and in vivo studies of biodegradable fine grained AZ31 magnesium alloy produced by equal channel angular pressing.

    PubMed

    Ratna Sunil, B; Sampath Kumar, T S; Chakkingal, Uday; Nandakumar, V; Doble, Mukesh; Devi Prasad, V; Raghunath, M

    2016-02-01

    The objective of the present work is to investigate the role of different grain sizes produced by equal channel angular pressing (ECAP) on the degradation behavior of magnesium alloy using in vitro and in vivo studies. Commercially available AZ31 magnesium alloy was selected and processed by ECAP at 300°C for up to four passes using route Bc. Grain refinement from a starting size of 46μm to a grain size distribution of 1-5μm was successfully achieved after the 4th pass. Wettability of ECAPed samples assessed by contact angle measurements was found to increase due to the fine grain structure. In vitro degradation and bioactivity of the samples studied by immersing in super saturated simulated body fluid (SBF 5×) showed rapid mineralization within 24h due to the increased wettability in fine grained AZ31 Mg alloy. Corrosion behavior of the samples assessed by weight loss and electrochemical tests conducted in SBF 5× clearly showed the prominent role of enhanced mineral deposition on ECAPed AZ31 Mg in controlling the abnormal degradation. Cytotoxicity studies by MTT colorimetric assay showed that all the samples are viable. Additionally, cell adhesion was excellent for ECAPed samples particularly for the 3rd and 4th pass samples. In vivo experiments conducted using New Zealand White rabbits clearly showed lower degradation rate for ECAPed sample compared with annealed AZ31 Mg alloy and all the samples showed biocompatibility and no health abnormalities were noticed in the animals after 60days of in vivo studies. These results suggest that the grain size plays an important role in degradation management of magnesium alloys and ECAP technique can be adopted to achieve fine grain structures for developing degradable magnesium alloys for biomedical applications.

  2. FMOE-MR: content-driven multiresolution MPEG-4 fine grained scalable layered video encoding

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Luo, X.; Bhandarkar, S. M.; Li, K.

    2007-01-01

    The MPEG-4 Fine Grained Scalability (FGS) profile aims at scalable layered video encoding, in order to ensure efficient video streaming in networks with fluctuating bandwidths. In this paper, we propose a novel technique, termed as FMOEMR, which delivers significantly improved rate distortion performance compared to existing MPEG-4 Base Layer encoding techniques. The video frames are re-encoded at high resolution at semantically and visually important regions of the video (termed as Features, Motion and Objects) that are defined using a mask (FMO-Mask) and at low resolution in the remaining regions. The multiple-resolution re-rendering step is implemented such that further MPEG-4 compression leads to low bit rate Base Layer video encoding. The Features, Motion and Objects Encoded-Multi- Resolution (FMOE-MR) scheme is an integrated approach that requires only encoder-side modifications, and is transparent to the decoder. Further, since the FMOE-MR scheme incorporates "smart" video preprocessing, it requires no change in existing MPEG-4 codecs. As a result, it is straightforward to use the proposed FMOE-MR scheme with any existing MPEG codec, thus allowing great flexibility in implementation. In this paper, we have described, and implemented, unsupervised and semi-supervised algorithms to create the FMO-Mask from a given video sequence, using state-of-the-art computer vision algorithms.

  3. Modeling methane bubble growth in fine-grained muddy aquatic sediments: correlation with sediment properties

    NASA Astrophysics Data System (ADS)

    Katsman, Regina

    2015-04-01

    Gassy sediments contribute to destabilization of aquatic infrastructure, air pollution, and global warming. In the current study a precise shape and size of the buoyant mature methane bubble in fine-grained muddy aquatic sediment is defined by numerical and analytical modeling, their results are in a good agreement. A closed-form analytical solution defining the bubble parameters is developed. It is found that the buoyant mature bubble is elliptical in its front view and resembles an inverted tear drop in its cross-section. The size and shape of the mature bubble strongly correlate with sediment fracture toughness. Bubbles formed in the weaker sediments are smaller and characterized by a larger surface-to volume ratio that induces their faster growth and may lead to their faster dissolution below the sediment-water interface. This may prevent their release to the water column and to the atmosphere. Shapes of the bubbles in the weaker sediments deviate further from the spherical configuration, than those in the stronger sediments. Modeled bubble characteristics, important for the acoustic applications, are in a good agreement with field observations and lab experiments.

  4. MROrchestrator: A Fine-Grained Resource Orchestration Framework for MapReduce Clusters

    SciTech Connect

    Sharma, Bikash; Prabhakar, Ramya; Kandemir, Mahmut; Das, Chita; Lim, Seung-Hwan

    2012-01-01

    Efficient resource management in data centers and clouds running large distributed data processing frameworks like MapReduce is crucial for enhancing the performance of hosted applications and boosting resource utilization. However, existing resource scheduling schemes in Hadoop MapReduce allocate resources at the granularity of fixed-size, static portions of nodes, called slots. In this work, we show that MapReduce jobs have widely varying demands for multiple resources, making the static and fixed-size slot-level resource allocation a poor choice both from the performance and resource utilization standpoints. Furthermore, lack of co-ordination in the management of mul- tiple resources across nodes prevents dynamic slot reconfigura- tion, and leads to resource contention. Motivated by this, we propose MROrchestrator, a MapReduce resource Orchestrator framework, which can dynamically identify resource bottlenecks, and resolve them through fine-grained, co-ordinated, and on- demand resource allocations. We have implemented MROrches- trator on two 24-node native and virtualized Hadoop clusters. Experimental results with a suite of representative MapReduce benchmarks demonstrate up to 38% reduction in job completion times, and up to 25% increase in resource utilization. We further show how popular resource managers like NGM and Mesos when augmented with MROrchestrator can hike up their performance.

  5. Fine-Grained Emotion Detection in Suicide Notes: A Thresholding Approach to Multi-Label Classification

    PubMed Central

    Luyckx, Kim; Vaassen, Frederik; Peersman, Claudia; Daelemans, Walter

    2012-01-01

    We present a system to automatically identify emotion-carrying sentences in suicide notes and to detect the specific fine-grained emotion conveyed. With this system, we competed in Track 2 of the 2011 Medical NLP Challenge,14 where the task was to distinguish between fifteen emotion labels, from guilt, sorrow, and hopelessness to hopefulness and happiness. Since a sentence can be annotated with multiple emotions, we designed a thresholding approach that enables assigning multiple labels to a single instance. We rely on the probability estimates returned by an SVM classifier and experimentally set thresholds on these probabilities. Emotion labels are assigned only if their probability exceeds a certain threshold and if the probability of the sentence being emotion-free is low enough. We show the advantages of this thresholding approach by comparing it to a naïve system that assigns only the most probable label to each test sentence, and to a system trained on emotion-carrying sentences only. PMID:22879761

  6. Fine-grained parallelism accelerating for RNA secondary structure prediction with pseudoknots based on FPGA.

    PubMed

    Xia, Fei; Jin, Guoqing

    2014-06-01

    PKNOTS is a most famous benchmark program and has been widely used to predict RNA secondary structure including pseudoknots. It adopts the standard four-dimensional (4D) dynamic programming (DP) method and is the basis of many variants and improved algorithms. Unfortunately, the O(N(6)) computing requirements and complicated data dependency greatly limits the usefulness of PKNOTS package with the explosion in gene database size. In this paper, we present a fine-grained parallel PKNOTS package and prototype system for accelerating RNA folding application based on FPGA chip. We adopted a series of storage optimization strategies to resolve the "Memory Wall" problem. We aggressively exploit parallel computing strategies to improve computational efficiency. We also propose several methods that collectively reduce the storage requirements for FPGA on-chip memory. To the best of our knowledge, our design is the first FPGA implementation for accelerating 4D DP problem for RNA folding application including pseudoknots. The experimental results show a factor of more than 50x average speedup over the PKNOTS-1.08 software running on a PC platform with Intel Core2 Q9400 Quad CPU for input RNA sequences. However, the power consumption of our FPGA accelerator is only about 50% of the general-purpose micro-processors.

  7. The Temperature Influence On The Properties Of The Fine - Grained Suspension Used In Underground Workings

    NASA Astrophysics Data System (ADS)

    Pomykała, Radosław; Kępys, Waldemar; Piotrowski, Zbigniew; Łyko, Paulina; Grzywa, Aleksandra

    2015-12-01

    Underground hard coal exploitation is often done under conditions of spontaneous fire hazard. The primary way to combat this threat is advanced, active or passive fire prevention. An important activity is the isolation of gobs using aqueous suspensions of fly ash as well as mineral binders. Therefore, the fine-grained suspension are often used in conditions of elevated temperature. The paper presents results of research on the effect of temperature (up to 80°C) on the properties of suspensions in a liquid state, including their rheological parameters and setting time. Suspensions prepared using the ashes from the hard coal combustion in fluidized bed boilers, and with the addition of Portland cement CEM I 42.5. During the research it was noted that the increased temperature significantly affect the acceleration of solidification processes of suspensions. In the case of rheological properties, the effect of temperature is ambiguous, among others, due to the phenomenon of sedimentation. However, in most cases, particularly for suspensions of higher solids content a marked increase in shear stress and viscosity of the suspensions with increasing temperature were observed.

  8. Biochronology and paleoecology of fine-grained sediments belonging to Esmeralda Formatino in Stewart Valley, Nevada

    SciTech Connect

    Starratt, S.W.

    1987-05-01

    Fine-grained rocks belonging to the middle Miocene Esmeralda Formation in Stewart Valley, Nevada, are rich in diatoms and ostracods as well as domal and subpherical stromatolites. In addition to their use as paleoecological indicators, the diatoms have also been used to date the rocks. The diatom flora, collected from a 45-m section consisting of thinly bedded to laminated siliceous shales, is dominated by Fragilaria construens (Ehrenberg) Grunow and Melosira granulata (Ehrenberg) Ralfs. This indicates that during the time represented, the waters in the deeper part of the lake were alkaline, clean, and low in salinity (0-5 per thousand). The lake was eutrophic and probably possessed a seasonal thermocline which was responsible for low-oxygen bottom waters at least part of the year. Varved rocks from another section in the valley tend to support this conclusion. The presence of the diatoms Coscinodiscus miocaenicus Krasske and Coscinodiscus grobunovii Scheschukova-Poretskaya in the deeper water deposits suggests an age of 12-15 Ma. This age is in agreement with that indicated by mammalian fossils present in closely associated rocks. The ostracod fauna suggests that the shallow waters of the lake may have been more saline. The domal and subspherical stromatolites indicate that the shallow-water environment was alkaline enough to exclude algae-grazing gastropods. Such gastropods appear in other parts of the lake.

  9. Storage media pipelining: Making good use of fine-grained media

    NASA Technical Reports Server (NTRS)

    Vanmeter, Rodney

    1993-01-01

    This paper proposes a new high-performance paradigm for accessing removable media such as tapes and especially magneto-optical disks. In high-performance computing the striping of data across multiple devices is a common means of improving data transfer rates. Striping has been used very successfully for fixed magnetic disks improving overall system reliability as well as throughput. It has also been proposed as a solution for providing improved bandwidth for tape and magneto-optical subsystems. However, striping of removable media has shortcomings, particularly in the areas of latency to data and restricted system configurations, and is suitable primarily for very large I/Os. We propose that for fine-grained media, an alternative access method, media pipelining, may be used to provide high bandwidth for large requests while retaining the flexibility to support concurrent small requests and different system configurations. Its principal drawback is high buffering requirements in the host computer or file server. This paper discusses the possible organization of such a system including the hardware conditions under which it may be effective, and the flexibility of configuration. Its expected performance is discussed under varying workloads including large single I/O's and numerous smaller ones. Finally, a specific system incorporating a high-transfer-rate magneto-optical disk drive and autochanger is discussed.

  10. Estimating suspended sediment using acoustics in a fine-grained riverine system, Kickapoo Creek at Bloomington, Illinois

    USGS Publications Warehouse

    Manaster, Amanda D.; Domanski, Marian M.; Straub, Timothy D.; Boldt, Justin A.

    2016-08-18

    Acoustic technologies have the potential to be used as a surrogate for measuring suspended-sediment concentration (SSC). This potential was examined in a fine-grained (97-100 percent fines) riverine system in central Illinois by way of installation of an acoustic instrument. Acoustic data were collected continuously over the span of 5.5 years. Acoustic parameters were regressed against SSC data to determine the accuracy of using acoustic technology as a surrogate for measuring SSC in a fine-grained riverine system. The resulting regressions for SSC and sediment acoustic parameters had coefficients of determination ranging from 0.75 to 0.97 for various events and configurations. The overall Nash-Sutcliffe model-fit efficiency was 0.95 for the 132 observed and predicted SSC values determined using the sediment acoustic parameter regressions. The study of using acoustic technologies as a surrogate for measuring SSC in fine-grained riverine systems is ongoing. The results at this site are promising in the realm of surrogate technology.

  11. Selenium extractability from a contaminated fine soil fraction: implication on soil cleanup.

    PubMed

    Lim, Teik-Thye; Goh, Kok-Hui

    2005-01-01

    Two batches of fine soil fraction of an acidic soil were deliberately contaminated with selenite (Se(IV)) and selenate (Se(VI)), respectively, and aged for more than 220 days. Speciation analysis using continuous flow-through hydride generation atomic absorption spectrometry (HGAAS) indicated that the species were predominant in their respective aged soils. A selective sequential extraction scheme was employed to fractionate the Se retained in the soils into six fractions of varying retentions. Abilities of various chemical reagents in extracting the Se in the two soil batches were then evaluated. The reagents investigated were sodium salts such as sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium carbonate (Na2CO3), and sodium phosphate (Na3PO4), and two oxidants, namely, hydrogen peroxide (H2O2) and potassium permanganate (KMnO4). It was found that NaCl, Na2SO4, and Na2CO3 could only extract the exchangeable fraction of Se, while Na3PO4 could extract the exchangeable and strongly-bound fractions. Selenate was extracted more than Se(IV) by the salts. The kinetics of Se(IV) extraction by Na3PO4 could be best described by the Elovich model, while the Ritchie second-order model was the most appropriate to describe Se(VI) extraction. Efficiencies of the oxidants in Se(IV) extraction highly depended on their applied dosages. Both H2O2 and KMnO4 were able to extract greater than 93% of total Se, and therefore were significantly more effective than the salts in Se(IV) extraction.

  12. Microstructure, Chemistry, and Origin of Grain Rims on ilmenite from the Lunar Soil Finest Fraction

    NASA Technical Reports Server (NTRS)

    Christoffersen, Roy; Keller, Lindsay P.; McKay, David S.

    1996-01-01

    Analytical transmission electron microscope (TEM) observations reveal that ilmenite grains sampled from the sub-10 micron size fraction of Apollo 11 (10084) and Apollo 16 (61221, 67701) soils have rims 10-300 nm thick that are chemically and microstructurally distinct from the host ilmenite. The rims have a thin outer sublayer 10-50 nm thick that contains the ilmenite-incompatible elements Si, Al, Ca and S. This overlies a relatively thicker (50-250 nm) inner sublayer of nanocrystalline Ti-oxide precipitates in a matrix of single-crystal ilmenite that is structurally continuous with the underlying host grain. Microstructural information, as well as data from x-ray spectrometry (EDS) and electron energy loss spectrometry (EELS) analysis of the inner sublayer, suggest that both the inner and outer sublayer assemblages are reduced and that the inner layer is depleted in Fe relative to the underlying ilmenite. The chemistry of the outer sublayer suggests that it is a surface deposit of sputtered or impact-vaporized components from the bulk lunar soil. The inner sublayer is part of the original host grain that has been physically and chemically processed, but not amorphized, by solar ion irradiation and possibly some subsolidus heating. The fact that the deposited outer sublayer is consistently much thinner than the radiation-altered inner sublayer indicates that only a minor fraction of the total rim volume is a product of vapor or sputter deposition. This finding is in contrast to recent descriptions of thick deposited layers on one-third of regolith silicate grains and indicates that ilmenite and silicate rims as a group are different in the fraction of deposited material that they contain.

  13. Morphology and processes associated with the accumulation of the fine-grained sediment deposit on the southern New England shelf

    USGS Publications Warehouse

    Twichell, David C.; McClennen, Charles E.; Butman, Bradford

    1981-01-01

    A 13,000 km2 area of the southern New England Continental Shelf which is covered by anomalously fine-grained sediment has been surveyed by means of high-resolution, seismic-reflection and side-scan sonar techniques to map its morphology and structure, and a near-bottom instrument system contributed to understanding present activity of the deposit. Seismic-reflection profiles show that the fine-grained deposit, which is as much as 13 m thick, has accumulated during the last transgression because it rests on a reflector that is geomorphically similar to and continuous with the Holocene transgressive sand sheet still exposed on the shelf to the west. The ridge and swale topography comprising the sand sheet on the shelf off New Jersey and Long Island are relict in origin as these same features are found buried under the fine sediment deposit. Southwestward migrating megaripples observed on the sonographs in the eastern part of the deposit are evidence that sediment is still actively accumulating in this area. In the western part of the deposit, where surface sediment is composed of silt plus clay, evidence of present sediment mobility consists of changes in the near-bottom, suspended-matter concentrations primarily associated with storms. Nantucket Shoals and Georges Bank are thought to be the sources for the fine-textured sediment. Storms and strong tidal currents in these shoal areas may still erode available fine-grained material, which then is transported westward by the mean drift to the southern New England Shelf, where a comparatively tranquil environment permits deposition of the fine material.

  14. Microstructure and Mechanical Properties of Ultra-Fine Grain Al-Zr Alloy Fabricated by Mechanical Alloying Process.

    PubMed

    Kim, Chung Seok; Kim, Il-Ho

    2015-08-01

    The ultra-fine grain Al-4Zr alloy has been successfully fabricated by a mechanical alloying process. The intermetallic Al3Zr phases strongly enhance the mechanical properties of Al-based alloy and prevent grain growth of alloy. The phase stability and transformation during mechanical alloying process have been investigated. The ultra-fine grain alloy has been successfully obtained. The thin film of Al-4Zr alloy has been observed by a transmission electron microscope. The equivalent grain size of as-milling specimen is 55 nm. After milling process, the specimens were heat treated at 350 °C to 650 °C. The equivalent grain size of heat treated specimens were 80 nm at 350 °C and 130 nm at 650 °C. Some of Zr atoms were dissolved into the Al matrix and most of them reacted with hydrogen produced by decomposition of PCA to form ZrH2 during mechanical alloying process. These ZrH2 hydrides decomposed gradually after the heat treatment. Stable A13Zr with a D023 structure was formed by heat treatment at temperature of 550 °C.

  15. High-flux plasma exposure of ultra-fine grain tungsten

    SciTech Connect

    Kolasinski, R. D.; Buchenauer, D. A.; Doerner, R. P.; Fang, Z. Z.; Ren, C.; Oya, Y.; Michibayashi, K.; Friddle, R. W.; Mills, B. E.

    2016-05-12

    Here we examine the response of an ultra-fine grained (UFG) tungsten material to high-flux deuterium plasma exposure. UFG tungsten has received considerable interest as a possible plasma-facing material in magnetic confinement fusion devices, in large part because of its improved resistance to neutron damage. However, optimization of the material in this manner may lead to trade-offs in other properties. Moreover, we address two aspects of the problem in this work: (a) how high-flux plasmas modify the structure of the exposed surface, and (b) how hydrogen isotopes become trapped within the material. The specific UFG tungsten considered here contains 100 nm-width Ti dispersoids (1 wt%) that limit the growth of the W grains to a median size of 960 nm. Metal impurities (Fe, Cr) as well as O were identified within the dispersoids; these species were absent from the W matrix. To simulate relevant particle bombardment conditions, we exposed specimens of the W-Ti material to low energy (100 eV), high-flux (> 1022 m-2 s-1) deuterium plasmas in the PISCES-A facility at the University of California, San Diego. To explore different temperature-dependent trapping mechanisms, we considered a range of exposure temperatures between 200 °C and 500 °C. For comparison, we also exposed reference specimens of conventional powder metallurgy warm-rolled and ITER-grade tungsten at 300 °C. Post-mortem focused ion beam profiling and atomic force microscopy of the UFG tungsten revealed no evidence of near-surface bubbles containing high pressure D2 gas, a common surface degradation mechanism associated with plasma exposure. Thermal desorption spectrometry indicated moderately higher trapping of D in the material compared with the reference specimens, though still within the spread of values for different tungsten grades found in the literature database. Finally, for the criteria considered here, these results do not indicate any significant obstacles to

  16. The Stability of Fine-grained Sediments from the Fraser River Delta

    NASA Astrophysics Data System (ADS)

    Amos, C. L.; Feeney, T.; Sutherland, T. F.; Luternauer, J. L.

    1997-10-01

    The stability and erodibility of benthic fine-grained sediments on the foreshore and upper foreslope of the Fraser River delta were measured using the in situbenthic flume—Sea Carousel. The erosion threshold [τ c(0)], which varied between 0·11 and 0·50 Pa, was inversely related to erosion rate. It was also proportional to sediment wet bulk density (ρ b) in the form: τ c(0)=7×10 -4 ρ b-0·47. This trend agreed with those obtained from four other sites across Canada that encompassed a wide range in sediment densities: 1000<ρ b<2000 kg m -3. Erosion threshold Shields parameter (θ c) was positively related to grain Reynolds number over the silt-clay size range (0·01< Re<5): θ c=2·86 Re0·58. This was similar to earlier findings for water-saturated sediment. This trend is also in continuity with published threshold values measured in biostabilized sand (5< Re<50). Copyright 1997 Academic Press Limited Three erosion types were observed: Type IA erosion was a surface phenomenon caused by the presence of a thin organic ' fluff ' layer. It occurred at current speeds less than 0·3 m s -1. Type 1B erosion (asymptotically decaying with time) characterized the mid-portions of each erosion time series, and occurred at current speeds of 0·3-0·9 m s -1. Type I/II erosion (transitional) was largely found on the foreslope, and occurred at current speeds in excess of 0·8 m s -1. The erosion process began in all cases under turbulent transitional flows. The change from Type I to Type II erosion corresponded to the onset of turbulent rough flows (60< Re<70). This is supported by video observations, which showed Type I erosion to be largely the result of entrainment of small aggregates and flocs, whereas Type II erosion was the result of enlargement of surface irregularities, and subsequent undercutting and release of large aggregates. Mean erosion rate ( Em) was independent of either azimuthal current speed or bed shear stress. It was largely constant throughout each

  17. High-flux plasma exposure of ultra-fine grain tungsten

    DOE PAGES

    Kolasinski, R. D.; Buchenauer, D. A.; Doerner, R. P.; ...

    2016-05-12

    Here we examine the response of an ultra-fine grained (UFG) tungsten material to high-flux deuterium plasma exposure. UFG tungsten has received considerable interest as a possible plasma-facing material in magnetic confinement fusion devices, in large part because of its improved resistance to neutron damage. However, optimization of the material in this manner may lead to trade-offs in other properties. Moreover, we address two aspects of the problem in this work: (a) how high-flux plasmas modify the structure of the exposed surface, and (b) how hydrogen isotopes become trapped within the material. The specific UFG tungsten considered here contains 100 nm-widthmore » Ti dispersoids (1 wt%) that limit the growth of the W grains to a median size of 960 nm. Metal impurities (Fe, Cr) as well as O were identified within the dispersoids; these species were absent from the W matrix. To simulate relevant particle bombardment conditions, we exposed specimens of the W-Ti material to low energy (100 eV), high-flux (> 1022 m-2 s-1) deuterium plasmas in the PISCES-A facility at the University of California, San Diego. To explore different temperature-dependent trapping mechanisms, we considered a range of exposure temperatures between 200 °C and 500 °C. For comparison, we also exposed reference specimens of conventional powder metallurgy warm-rolled and ITER-grade tungsten at 300 °C. Post-mortem focused ion beam profiling and atomic force microscopy of the UFG tungsten revealed no evidence of near-surface bubbles containing high pressure D2 gas, a common surface degradation mechanism associated with plasma exposure. Thermal desorption spectrometry indicated moderately higher trapping of D in the material compared with the reference specimens, though still within the spread of values for different tungsten grades found in the literature database. Finally, for the criteria considered here, these results do not indicate any significant obstacles to the potential use of UFG

  18. Amino acid composition of some Amaranthus sp. grain proteins and of its fractions.

    PubMed

    Correa, A D; Jokl, L; Carlsson, R

    1986-09-01

    This study was carried out to determine the protein content of several Amaranthus sp. grains. Findings revealed this has a high lysine (5.3 to 6.3 of the protein) and sulphur amino acids content (3.4-4.0%), while leucine could well be limiting when those seeds are used as a sole protein source in food. Using the correction for in vitro protein digestibility, the chemical score varied from 50 to 67. The calculated protein efficiency ratios and biological values ranged from 1.39 to 1.80 and 53 to 68, respectively. Considering that amaranth grain is a good supplement to cereal grain, the protein of A. hypochondriacus HH5 (yellow seeds) and A. anclancalius (black seeds) was fractionated into albumin, globulin, prolamin and glutelin. The average proportions between those soluble proteins were 65:17:11:7, respectively. Albumin had the highest lysine content (7.3-8.2%), and globulin the highest methionine (4.1-5.3%) and phenylalanine (6.0-6.1%) content. Prolamin had the highest threonine (4.6-5.4%) and leucine (6.8-6.9%) content, while glutelin had a very low methionine content (0.6-1.0%). Based on the above-mentioned findings, the authors conclude the variation in the amino acid composition of the protein fractions can be used for genetic protein improvement.

  19. Permeability Enhancement in Fine-Grained Sediments by Chemically Induced Clay Fabric Shrinkage

    SciTech Connect

    Wijesinghe, A M; Kansa, E J; Viani, B E; Blake, R G; Roberts, J J; Huber, R D

    2004-02-26

    The National Research Council [1] identified the entrapment of contaminants in fine-grained clay-bearing soils as a major impediment to the timely and cost-effective remediation of groundwater to regulatory standards. Contaminants trapped in low-permeability, low-diffusivity, high-sorptivity clays are not accessible to advective flushing by treatment fluids from permeable zones, and slowly diffuse out to recontaminate previously cleaned permeable strata. We propose to overcome this barrier to effective remediation by exploiting the ability of certain nontoxic EPA-approved chemicals (e.g., ethanol) to shrink and alter the fabric of clays, and thereby create macro-porosity and crack networks in fine-grained sediments. This would significantly reduce the distance and time scales of diffusive mass transport to advectively flushed boundaries, to yield orders of magnitude reduction in the time required to complete remediation. Given that effective solutions to this central problem of subsurface remediation do not yet exist, the cost and time benefits of successful deployment of this novel concept, both as a stand-alone technology and as an enabling pre-treatment for other remedial technologies that rely on advective delivery, is likely to be very large. This project, funded as a 1-year feasibility study by LLNL's LDRD Program, is a multi-directorate, multi-disciplinary effort that leverages expertise from the Energy & Environment Directorate, the Environmental Restoration Division, and the Manufacturing & Materials Evaluation Division of Mechanical Engineering. In this feasibility study, a ''proof-of-principle'' experiment was performed to answer the central question: ''Can clay shrinkage induced by ethanol in clay-bearing sediments overcome realistic confining stresses, crack clay, and increase its effective permeability by orders of magnitude within a time that is much smaller than the time required for diffusive mass transport of ethanol in the unaltered sediment

  20. Fine-grained Database Field Search Using Attribute-Based Encryption for E-Healthcare Clouds.

    PubMed

    Guo, Cheng; Zhuang, Ruhan; Jie, Yingmo; Ren, Yizhi; Wu, Ting; Choo, Kim-Kwang Raymond

    2016-11-01

    An effectively designed e-healthcare system can significantly enhance the quality of access and experience of healthcare users, including facilitating medical and healthcare providers in ensuring a smooth delivery of services. Ensuring the security of patients' electronic health records (EHRs) in the e-healthcare system is an active research area. EHRs may be outsourced to a third-party, such as a community healthcare cloud service provider for storage due to cost-saving measures. Generally, encrypting the EHRs when they are stored in the system (i.e. data-at-rest) or prior to outsourcing the data is used to ensure data confidentiality. Searchable encryption (SE) scheme is a promising technique that can ensure the protection of private information without compromising on performance. In this paper, we propose a novel framework for controlling access to EHRs stored in semi-trusted cloud servers (e.g. a private cloud or a community cloud). To achieve fine-grained access control for EHRs, we leverage the ciphertext-policy attribute-based encryption (CP-ABE) technique to encrypt tables published by hospitals, including patients' EHRs, and the table is stored in the database with the primary key being the patient's unique identity. Our framework can enable different users with different privileges to search on different database fields. Differ from previous attempts to secure outsourcing of data, we emphasize the control of the searches of the fields within the database. We demonstrate the utility of the scheme by evaluating the scheme using datasets from the University of California, Irvine.

  1. Laboratory Investigation of Electro-Osmotic Remediation of Fine-Grained Sediments

    SciTech Connect

    Cherepy, N.; Wildenschild, D.; Elsholz, A.

    2000-02-23

    Electro-osmosis, a coupled-flow phenomenon in which an applied electrical potential gradient drives water flow, may be used to induce water flow through fine-grained sediments. We plan to use this technology to remediate chlorinated solvent-contaminated clayey zones at the LLNL site. The electro-osmotic conductivity (k{sub e}) determined from bench-top studies for a core extracted from a sediment zone 36.4-36.6 m below surface was initially 7.37 x 10{sup -10} m{sup 2}/s-V, decreasing to 3.44 x 10{sup -10} m{sup 2}/s-V, after electro-osmotically transporting 0.70 pore volumes of water through it (195 ml). Hydraulic conductivity (k{sub h}) of the same core was initially measured to be 5.00 x 10{sup -10} m/s, decreasing to 4.08 x 10{sup -10} m/s at the end of processing. This decline in permeability is likely due to formation of a chemical precipitation zone within the core. Water splitting products and ions electromigrate and precipitate within the core; H{sup +} and metal cations migrate toward the cathode, and OH{sup -} from the cathode moves toward the anode. We are now exploring how to minimize this effect using pH control. The significance of this technology is that for this core, a 3 V/cm voltage gradient produced an initial effective hydraulic conductivity of 2.21 x 10{sup -7} m/s, >400x greater than the initial hydraulic conductivity.

  2. Fine-Grained, Local Maps and Coarse, Global Representations Support Human Spatial Working Memory

    PubMed Central

    Katshu, Mohammad Zia Ul Haq; d'Avossa, Giovanni

    2014-01-01

    While sensory processes are tuned to particular features, such as an object's specific location, color or orientation, visual working memory (vWM) is assumed to store information using representations, which generalize over a feature dimension. Additionally, current vWM models presume that different features or objects are stored independently. On the other hand, configurational effects, when observed, are supposed to mainly reflect encoding strategies. We show that the location of the target, relative to the display center and boundaries, and overall memory load influenced recall precision, indicating that, like sensory processes, capacity limited vWM resources are spatially tuned. When recalling one of three memory items the target distance from the display center was overestimated, similar to the error when only one item was memorized, but its distance from the memory items' average position was underestimated, showing that not only individual memory items' position, but also the global configuration of the memory array may be stored. Finally, presenting the non-target items at recall, consequently providing landmarks and configurational information, improved precision and accuracy of target recall. Similarly, when the non-target items were translated at recall, relative to their position in the initial display, a parallel displacement of the recalled target was observed. These findings suggest that fine-grained spatial information in vWM is represented in local maps whose resolution varies with distance from landmarks, such as the display center, while coarse representations are used to store the memory array configuration. Both these representations are updated at the time of recall. PMID:25259601

  3. Development of manufacturing systems for nanocrystalline and ultra-fine grain materials employing indexing equal channel angular pressing

    NASA Astrophysics Data System (ADS)

    Hester, Michael Wayne

    Nanotechnology offers significant opportunities in providing solutions to existing engineering problems as well as breakthroughs in new fields of science and technology. In order to fully realize benefits from such initiatives, nanomanufacturing methods must be developed to integrate enabling constructs into commercial mainstream. Even though significant advances have been made, widespread industrialization in many areas remains limited. Manufacturing methods, therefore, must continually be developed to bridge gaps between nanoscience discovery and commercialization. A promising technology for integration of top-down nanomanufacturing yet to receive full industrialization is equal channel angular pressing, a process transforming metallic materials into nanostructured or ultra-fine grained materials with significantly improved performance characteristics. To bridge the gap between process potential and actual manufacturing output, a prototype top-down nanomanufacturing system identified as indexing equal channel angular pressing (IX-ECAP) was developed. The unit was designed to capitalize on opportunities of transforming spent or scrap engineering elements into key engineering commodities. A manufacturing system was constructed to impose severe plastic deformation via simple shear in an equal channel angular pressing die on 1100 and 4043 aluminum welding rods. 1/4 fraction factorial split-plot experiments assessed significance of five predictors on the response, microhardness, for the 4043 alloy. Predictor variables included temperature, number of passes, pressing speed, back pressure, and vibration. Main effects were studied employing a resolution III design. Multiple linear regression was used for model development. Initial studies were performed using continuous processing followed by contingency designs involving discrete variable length work pieces. IX-ECAP offered a viable solution in severe plastic deformation processing. Discrete variable length work piece

  4. Evolution of Fine-Grained Channel Margin Deposits behind Large Woody Debris in an Experimental Gravel-Bed Flume

    NASA Astrophysics Data System (ADS)

    ONeill, B.; Marks, S.; Skalak, K.; Puleo, J. A.; Wilcock, P. R.; Pizzuto, J. E.

    2014-12-01

    Fine grained channel margin (FGCM) deposits of the South River, Virginia sequester a substantial volume of fine-grained sediment behind large woody debris (LWD). FGCM deposits were created in a laboratory setting meant to simulate the South River environment using a recirculating flume (15m long by 0.6m wide) with a fixed gravel bed and adjustable slope (set to 0.0067) to determine how fine sediment is transported and deposited behind LWD. Two model LWD structures were placed 3.7 m apart on opposite sides of the flume. A wire mesh screen with attached wooden dowels simulated LWD with an upstream facing rootwad. Six experiments with three different discharge rates, each with low and high sediment concentrations, were run. Suspended sediment was very fine grained (median grain size of 3 phi) and well sorted (0.45 phi) sand. Upstream of the wood, water depths averaged about 0.08m, velocities averaged about 0.3 m/s, and Froude numbers averaged around 0.3. Downstream of the first LWD structure, velocities were reduced tenfold. Small amounts of sediment passed through the rootwad and fell out of suspension in the area of reduced flow behind LWD, but most of the sediment was carried around the LWD by the main flow and then behind the LWD by a recirculating eddy current. Upstream migrating dunes formed behind LWD due to recirculating flow, similar to reattachment bars documented in bedrock canyon rivers partially obstructed by debouching debris fans. These upstream migrating dunes began at the reattachment point and merged with deposits formed from sediment transported through the rootwad. Downstream migrating dunes formed along the channel margin behind the LWD, downstream of the reattachment point. FGCM deposits were about 3 m long, with average widths of about 0.8 m. Greater sediment concentration created thicker FGCM deposits, and higher flows eroded the sides of the deposits, reducing their widths.

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

    DTIC Science & Technology

    2010-01-01

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

  6. Mineralogy and petrology of Stardust particles encased in the bulb of track 80: TEM investigation of the Wild 2 fine-grained material

    NASA Astrophysics Data System (ADS)

    Stodolna, Julien; Jacob, Damien; Leroux, Hugues

    2012-06-01

    We have characterized by transmission electron microscopy the mineralogy of samples extracted from the walls of the Stardust track 80. More than 500 fragments were studied using conventional imaging, electron diffraction and EDX microanalysis. Two categories of particles are distinguishable in equal proportions (wt%). The first one is comprised of relatively large crystalline grains (≈1 μm on average), dominated by silicates (olivine and pyroxene). They display a wide range of compositions and microstructures comparable to those found in terminal particles. Minor phases including magnetite and apatite are also present. Their occurrence suggests that the Wild 2 material underwent aqueous alteration to some extent. The second type of particle, called GEMS-like material, is made of silica-rich glassy clumps embedding iron sulfide beads and vesicles. Their microstructure is characteristic of thermally modified particles that have suffered strong interaction with the silica aerogel during the hypervelocity impact. This melted material may form by shedding of melted and vaporized material, but given the shape of the impact track and high diversity of surviving mineral compositions, much of it originated from fine-grained aggregates that disaggregated during the collection. Chemical mapping at the nano-scale allowed the localization of individual components within the silica-rich glass. They are dominated by Mg-rich components with a size less than 300 nm. The average composition of this thermally modified material is close to the solar abundance for the major elements Fe, Mg and S. The fine-grained material has probably not been chemically fractionated in the protoplanetary disk before its incorporation in comet Wild 2 unlike the sulfur depleted matrix of chondrites. From these two categories of particles, we deduce that Wild 2 is likely made of an assemblage of relatively large evolved grains (first category) cemented by a fine-grained material with primitive

  7. An improved snow hydrology for GCMS. Part 1: Snow cover fraction, albedo, grain size, and age

    SciTech Connect

    Marshall, S.; Oglesby, R.J.

    1994-07-01

    A new, physically-based snow hydrology has been implemented into the NCAR CCM1. The snow albedo is based on snow depth, solar zenith angle, snow cover pollutants, cloudiness, and a new parameter, the snow grain size. Snow grain size in turn depends on temperature and snow age. An improved expression is used for fractional snow cover which relates it to surface roughness and to snow depth. Each component of the new snow hydrology was implemented separately and then combined to make a new control run integrated for ten seasonal cycles. With the new snow hydrology, springtime snow melt occurs more rapidly, leading to a more reasonable late spring and summer distribution of snow cover. Little impact is seen on winter snow cover, since the new hydrology affects snow melt directly, but snowfall only indirectly, if at all. The influence of the variable grain size appears more important when snow packs are relatively deep while variable fractional snow cover becomes increasingly important as the snow pack thins. Variable surface roughness affects the snow cover fraction directly, but shows little effect on the seasonal cycle of the snow line. As an application of the new snow hydrology, we have rerun simulations involving Antarctic and Northern Hemisphere glaciation. Relatively little difference is seen for Antarctica, but a profound difference occurs for the Northern Hemisphere. In particular, ice sheets computed using new snow accumulations from the GCM are more numerous and larger in extent with the new snow hydrology. The new snow hydrology leads to a better simulation of the seasonal cycle of snow cover, however, our primary goal in implementing it into the GCM is to improve the predictive capabilities of the model. Since the snow hydrology is based on fundamental physical processes, and has well-defined parameters. it should enable model simulations of climatic change in which we have increased confidence. 37 refs., 15 figs., 2 tabs.

  8. Effect of the Fine-Grained Structure on the Fatigue Properties of the Heat-Resistant Nickel-Iron Alloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Mukhtarov, Sh. Kh.; Shakhov, R. V.

    2015-10-01

    It is well known that ultrafine-grained nickel alloys with average grain sizes d = 0.1-1 μm possess improved hot workability and can be used for superplastic forming or rolling. However, microstructure refinement can worsen some performance characteristics of the alloy, for example, heat-resistant or fatigue properties. In the present work, fatigue characteristics of the fine-grained alloy Inconel 718 are investigated. Ultrafine-grained alloys with average grain sizes d = 0.1-1 μm were manufactured by multiple forging with stage-by-stage deformation temperature decrease. During standard heat treatment of the alloy performed to obtain the desired properties, the γ-grain size was controlled by precipitations of δ-phase particles along the boundaries. Results of low-cycle fatigue tests of the fine-grained alloy at room and elevated temperatures are compared with the properties of the coarse-grained alloy.

  9. Influence of a reduced gravity on the volume fraction of a monolayer of spherical grains.

    PubMed

    Dorbolo, S; Scheller, T; Ludewig, F; Lumay, G; Vandewalle, N

    2011-10-01

    Centrifuge force is used to study granular materials in low gravity conditions. We consider a monolayer of noncohesive spherical grains placed on a plate. Reduced gravity conditions can be simulated in the plane by tilting or by rotating the plate. We compare both approaches experimentally. The volume fraction is found to increase with the apparent gravity and saturates. A model based on the exponential distribution of the Voronoi cell areas has been built and is in excellent agreement with the experimental data by extrapolating the fits of the data. Moreover, numerical simulations exhibit that more arches can be maintained at low apparent gravities than at high.

  10. The distribution of fine fraction of lunar soil obtained by remote sensing.

    NASA Astrophysics Data System (ADS)

    Shevchenko, V. V.; Skobeleva, T. P.

    1995-02-01

    With a given model for granulometric composition of soil, the estimation of a mean (or effective) size of particles can be made from the measured values of A and Pmax for each of the objects under observation. In the paper the previously derived relationship was used: log D = 5.552 log A + 3.410 log Pmax -7.092, where D is an effective size of particles in μm, A is albedo in %, and Pmax is the maximum degree of polarization measured by percentage. As a basis for the calculations of effective sizes of particles, the values of albedo and maximum degree of polarization were used on 190 sites (λ = 0.440 μm) from the Kvaratskheliya catalog [1988], on 21 sites (λ = 0.420 μm) from the Shkuratov et al. catalog [1993], and on 142 sites (λ = 0.600 μm) from the Dollfus and Deschamps catalog [1986]. These data show, that younger objects predominate by virtue of a coarser fraction of lunar soil in the surface layer (new craters, bright rays of new craters). However, the floor of the old crater Grimaldi, which is covered by maturer regolith, contains soil with a substantial predominance of a fine powdered fraction.

  11. Temperature dependence of magnetic behaviour in very fine grained, spark plasma sintered NiCuZn ferrites

    SciTech Connect

    Ahmadi, Behzad; Zehani, Karim; LoBue, Martino; Loyau, Vincent; Mazaleyrat, Frederic

    2012-04-01

    Recently, using spark plasma sintering technique, a family of very fine grained, fully dense NiCuZn ferrites have been produced, which show constant permeability up to several 10 MHz. These ferrites can be used for filtering purposes in high frequency applications where a wide frequency band is required. In this paper, we study the magnetization processes taking place in these nano grained materials, in the frequency interval of 100 kHz to 5 MHz. Using a fluxmetric hysteresis graph, permeability, loss, and BH loops are measured at different temperatures, from -5 deg. C to 110 deg. C. Results are compared to the behavior of micrometric grain size ferrites, which are commonly used for power electronic and high frequency applications.

  12. Matrix and fine-grained rims in the unequilibrated CO3 chondrite, ALHA77307 - Origins and evidence for diverse, primitive nebular dust components

    NASA Astrophysics Data System (ADS)

    Brearley, A. J.

    1993-04-01

    SEM, TEM, and electron microprobe analysis were used to investigate in detail the mineralogical and chemical characteristics of dark matrix and fine-grained rims in the unequilibrated CO3 chondrite ALHA77307. Data obtained revealed that there was a remarkable diversity of distinct mineralogical components, which can be identified using their chemical and textural characteristics. The matrix and rim components in ALHA77307 formed by disequilibrium condensation process as fine-grained amorphous dust that is represented by the abundant amorphous component in the matrix. Subsequent thermal processing of this condensate material, in a variety of environments in the nebula, caused partial or complete recrystallization of the fine-grained dust.

  13. Ti distribution in grain-size fractions of Apollo soils 10084 and 71501

    NASA Astrophysics Data System (ADS)

    Kong, W. G.; Jolliff, B. L.; Wang, Alian

    2013-09-01

    Much work has been devoted to the correlation between the remotely sensed UV-VIS slope and the TiO2 concentration of the lunar surface, and this correlation has been used to map the lunar surface TiO2 distributions using data obtained from various missions. However, additional work is needed to fully evaluate the UV-VIS-TiO2 correlation. Such work would help ongoing efforts to improve TiO2 mapping (e.g., as currently underway with LROC Wide Angle Camera (WAC) data). To evaluate the UV-VIS-TiO2 correlation, we are investigating soil petrographic factors (e.g., modal abundances of Ti bearing minerals, lithic, and glass hosts, ilmenite morphology, grain size, and maturity) that may influence the spectra. This “ground truth” approach will be useful in comparing between sample information and laboratory spectra to investigate the influence of petrographic factors on the spectra. In this work, we report the quantitative results of a systematic laboratory investigation of three size fractions (210-100 μm, 100-48 μm, 48-20 μm) of two high Ti lunar soils 10084 and 71501 using a combined digital imaging (backscattered electron image and X-ray maps) method. For each size fraction, the results include: (1) the modal abundances for single phase minerals and lithologic components; (2) the Ti distributions among Ti host components; and (3) the shape of ilmenite grains. We compile and compare the data together for the three size fractions of the two high Ti soils with different maturities as well as data from previous studies. Future work will include the investigation of finer size fractions (<20 μm) and more samples (Apollo 12, Apollo 15) covering a larger range of Ti concentration and maturity, and comparison with their spectra.

  14. A method for the concentration of fine-grained rutile (TiO2) from sediment and sedimentary rocks by chemical leaching

    USGS Publications Warehouse

    Commeau, Judith A.; Valentine, Page C.

    1991-01-01

    Most of the sample analyzed by the method described were marine muds collected from the Gulf of Maine (Valentine and Commeau, 1990). The silt and clay fraction (up to 99 wt% of the sediment) is composed of clay minerals (chiefly illite-mica and chlorite), silt-size quartz and feldspar, and small crystals (2-12 um) of rutile and hematite. The bulk sediment samples contained an average of 2 to 3 wt percent CaCO3. Tiher samples analyzed include red and gray Carboniferous and Triassic sandstones and siltstones exposed around the Bay of Fundy region and Paleozoic sandstones, siltstones, and shales from northern Maine and New Brunswick. These rocks are probable sources for the fine-grained rutile found in the Gulf of Maine.

  15. Enhancing of chemical compound and drug name recognition using representative tag scheme and fine-grained tokenization

    PubMed Central

    2015-01-01

    Background The functions of chemical compounds and drugs that affect biological processes and their particular effect on the onset and treatment of diseases have attracted increasing interest with the advancement of research in the life sciences. To extract knowledge from the extensive literatures on such compounds and drugs, the organizers of BioCreative IV administered the CHEMical Compound and Drug Named Entity Recognition (CHEMDNER) task to establish a standard dataset for evaluating state-of-the-art chemical entity recognition methods. Methods This study introduces the approach of our CHEMDNER system. Instead of emphasizing the development of novel feature sets for machine learning, this study investigates the effect of various tag schemes on the recognition of the names of chemicals and drugs by using conditional random fields. Experiments were conducted using combinations of different tokenization strategies and tag schemes to investigate the effects of tag set selection and tokenization method on the CHEMDNER task. Results This study presents the performance of CHEMDNER of three more representative tag schemes-IOBE, IOBES, and IOB12E-when applied to a widely utilized IOB tag set and combined with the coarse-/fine-grained tokenization methods. The experimental results thus reveal that the fine-grained tokenization strategy performance best in terms of precision, recall and F-scores when the IOBES tag set was utilized. The IOBES model with fine-grained tokenization yielded the best-F-scores in the six chemical entity categories other than the "Multiple" entity category. Nonetheless, no significant improvement was observed when a more representative tag schemes was used with the coarse or fine-grained tokenization rules. The best F-scores that were achieved using the developed system on the test dataset of the CHEMDNER task were 0.833 and 0.815 for the chemical documents indexing and the chemical entity mention recognition tasks, respectively. Conclusions The

  16. Si-bearing metal and niningerite in Almahata Sitta fine-grained ureilites and insights into the diversity of metal on the ureilite parent body

    NASA Astrophysics Data System (ADS)

    Horstmann, Marian; Humayun, Munir; Fischer-Gödde, Mario; Bischoff, Addi; Weyrauch, Mona

    2014-10-01

    A detailed mineralogical and chemical study of Almahata Sitta fine-grained ureilites (MS-20, MS-165, MS-168) was performed to shed light on the origin of these lithologies and their sulfide and metal. The Almahata Sitta fine-grained ureilites (silicates <30 μm grain size) show textural and chemical evidence for severe impact smelting as described for other fine-grained ureilites. Highly reduced areas in Almahata Sitta fine-grained ureilites show large (up to ˜1 mm) Si-bearing metal grains (up to ˜4.5 wt% Si) and niningerite [Mg>0.5,(Mn,Fe)<0.5S] with some similarities to the mineralogy of enstatite (E) chondrites. Overall, metal grains show a large compositional variability in Ni and Si concentrations. Niningerite grains probably formed as a by-product of smelting via sulfidation. The large Si-Ni variation in fine-grained ureilite metal could be the result of variable degrees of reduction during impact smelting, inherited from coarse-grained ureilite precursors, or a combination of both. Large Si-bearing metal grains probably formed via coalescence of existing and newly formed metal during impact smelting. Bulk and in situ siderophile trace element abundances indicate three distinct populations of (1) metal crystallized from partial melts in MS-20, (2) metal resembling bulk chondritic compositions in MS-165, and (3) residual metal in MS-168. Almahata Sitta fine-grained ureilites developed their distinctive mineralogy due to severe reduction during smelting. Despite the presence of E chondrite and ureilite stones in the Almahata Sitta fall, a mixing relation of E chondrites or their constituents and ureilite material in Almahata Sitta can be ruled out based on isotopic, textural, and mineral-chemical reasons.

  17. Rheology of fine-grained forsterite aggregate under deep upper mantle conditions

    NASA Astrophysics Data System (ADS)

    Nishihara, Y.; Ohuchi, T.; Kawazoe, T.; Spengler, D.; Tasaka, M.; Hiraga, T.; Kikegawa, T.; Suzuki, A.; Ohtani, E.

    2010-12-01

    Under the conditions of the Earth’s mantle, both diffusion creep and dislocation creep can be the dominant deformation mechanism depending on physical and chemical environments. These two mechanisms are quite different in terms of stress dependence of viscosity and development of lattice-preferred orientation. Thus it is important to understand the dominant deformation mechanism in the mantle. Previous studies on rheology of olivine under high-pressure (>3 GPa) mostly focused on dislocation creep (e.g. Kawazoe et al., 2009; Durham et al., 2009). Knowledge of diffusion creep of olivine under deep upper mantle condition (>100 km) has been quite limited. In order to clarify the dominant deformation mechanism in the upper mantle, we have conducted deformation experiments at high-pressure and high-temperature using fine-grained forsterite aggregate. Experiments were carried out using a D-DIA apparatus “D-CAP (deformation cubic-anvil press)” installed at NE7 beamline, PF-AR, High Energy Accelerator Research Institute, Tsukuba, Japan. The samples are sintered aggregate of 90%forsterite + 10%enstatite with average grain size of ~1 μm. High-pressure was generated by MA6-6 assembly (e.g. Kawazoe et al., 2010) using cubic (Mg,Co)O pressure medium and WC anvils with 5 mm truncation edge length. High-temperature was generated using graphite furnace and was monitored by WRe thermocouple. Deformation experiments were conducted at pressure of 3-5.5 GPa, temperature of 1573 K, and uniaxial strain rate of 7 x 10-6-2 x 10-4 s-1. Sample stress was measured by two-dimensional X-ray diffraction using monochromatized synchrotron X-ray (50 keV) and imaging plate detector (e.g. Nishihara et al., 2009). Sample strain was measured by X-ray radiography. H2O concentration in starting material and recovered samples was determined based on FTIR analyses (Paterson, 1982). Steady state flow stress was determined at each deformation condition. The stress-strain rate data taken at

  18. From bird to sparrow: Learning-induced modulations in fine-grained semantic discrimination.

    PubMed

    De Meo, Rosanna; Bourquin, Nathalie M-P; Knebel, Jean-François; Murray, Micah M; Clarke, Stephanie

    2015-09-01

    Recognition of environmental sounds is believed to proceed through discrimination steps from broad to more narrow categories. Very little is known about the neural processes that underlie fine-grained discrimination within narrow categories or about their plasticity in relation to newly acquired expertise. We investigated how the cortical representation of birdsongs is modulated by brief training to recognize individual species. During a 60-minute session, participants learned to recognize a set of birdsongs; they improved significantly their performance for trained (T) but not control species (C), which were counterbalanced across participants. Auditory evoked potentials (AEPs) were recorded during pre- and post-training sessions. Pre vs. post changes in AEPs were significantly different between T and C i) at 206-232ms post stimulus onset within a cluster on the anterior part of the left superior temporal gyrus; ii) at 246-291ms in the left middle frontal gyrus; and iii) 512-545ms in the left middle temporal gyrus as well as bilaterally in the cingulate cortex. All effects were driven by weaker activity for T than C species. Thus, expertise in discriminating T species modulated early stages of semantic processing, during and immediately after the time window that sustains the discrimination between human vs. animal vocalizations. Moreover, the training-induced plasticity is reflected by the sharpening of a left lateralized semantic network, including the anterior part of the temporal convexity and the frontal cortex. Training to identify birdsongs influenced, however, also the processing of C species, but at a much later stage. Correct discrimination of untrained sounds seems to require an additional step which results from lower-level features analysis such as apperception. We therefore suggest that the access to objects within an auditory semantic category is different and depends on subject's level of expertise. More specifically, correct intra

  19. Comparative analysis of dose rates in bricks determined by neutron activation analysis, alpha counting and X-ray fluorescence analysis for the thermoluminescence fine grain dating method

    NASA Astrophysics Data System (ADS)

    Bártová, H.; Kučera, J.; Musílek, L.; Trojek, T.

    2014-11-01

    In order to evaluate the age from the equivalent dose and to obtain an optimized and efficient procedure for thermoluminescence (TL) dating, it is necessary to obtain the values of both the internal and the external dose rates from dated samples and from their environment. The measurements described and compared in this paper refer to bricks from historic buildings and a fine-grain dating method. The external doses are therefore negligible, if the samples are taken from a sufficient depth in the wall. However, both the alpha dose rate and the beta and gamma dose rates must be taken into account in the internal dose. The internal dose rate to fine-grain samples is caused by the concentrations of natural radionuclides 238U, 235U, 232Th and members of their decay chains, and by 40K concentrations. Various methods can be used for determining trace concentrations of these natural radionuclides and their contributions to the dose rate. The dose rate fraction from 238U and 232Th can be calculated, e.g., from the alpha count rate, or from the concentrations of 238U and 232Th, measured by neutron activation analysis (NAA). The dose rate fraction from 40K can be calculated from the concentration of potassium measured, e.g., by X-ray fluorescence analysis (XRF) or by NAA. Alpha counting and XRF are relatively simple and are accessible for an ordinary laboratory. NAA can be considered as a more accurate method, but it is more demanding regarding time and costs, since it needs a nuclear reactor as a neutron source. A comparison of these methods allows us to decide whether the time- and cost-saving simpler techniques introduce uncertainty that is still acceptable.

  20. Dynamics of deposited fly-ash and fine grained magnetite in sandy material of different porosity (column experiments)

    NASA Astrophysics Data System (ADS)

    Kapicka, Ales; Kodesova, Radka; Petrovsky, Eduard; Grison, Hana

    2010-05-01

    Several studies confirm that soil magnetometry can serve as proxy of industrial immisions as well as heavy-metal contamination. The important assumption for magnetic mapping of contaminated soils is that atmospherically deposited particulate matter, including the ferrimagnetic phase, accumulates in the top soil horizons and remains there over long period. Only if this is true, large areas can be reliably mapped using soil magnetometry, and, moreover, this method can be used also for long-term monitoring. However, in soil types such as sandy soils with different porosity or soils with substantial variability of water regime, translocation of the deposited anthropogenic particles may result in biased (underestimated) values of the measured topsoil magnetic susceptibility. From the physical point of view, this process may be considered as colloid transport through porous medium. In our column experiments in laboratory we used three technical sands with different particle sizes (0,63 - 1.25mm, 0,315-0,80mm, 0,10-0,63mm). Sands in cylinders were contaminated on the surface by fly-ashes from coal-burning power plant (mean grain size 10μm) and fine grained Fe3O4 (grain size < 20 μm). Soil moisture sensors were used to monitor water regime within the sand columns after controlled rain simulation and temperature distribution in sand column was measured as well. Vertical migration of ferrimagnetic particles-tracers presented in the fly-ash was measured by SM 400 Kappameter. By means of magnetic susceptibility distribution we studied two parameters: gradual shift of peak concentration of contaminants (relative to surface layer) and maximum penetration depth. Results indicated that after rain simulation (pulls infiltration of defined water volume) the positions of peak values moved downwards compared to the initial state and gradual decrease of susceptibility peak values were detected in all studied sand formations. Fly-ash migrated more or less freely in coarse sand

  1. Doping Effect on High-Temperature Plastic Flow in Fine-grained Alumina (Invited)

    NASA Astrophysics Data System (ADS)

    Yoshida, H.; Ikuhara, Y.; Sakuma, T.

    2010-12-01

    High-temperature plastic flow controlled by matter transport in the grain boundaries of Al2O3 is briefly introduced with a special interest in the effect of cation doping. According to the deformation mechanism map compiled for polycrystalline Al2O3, the predominant deformation mechanism in Al2O3 with a grain size of less than 10μm is grain boundary diffusional creep at temperatures of 1100-1400°C and an applied stress of less than 100MPa. The grain boundary sliding becomes important in the deformation mechanism when the grain size is smaller than several microns. Our group has found that the high-temperature creep rate in Al2O3 with an average grain size of less than 5μm is sensitively influenced by the doping of a small amount of cations at the doping level of 0.1mol%. For instance, the high-temperature creep rate in Al2O3 with a grain size of 1μm is retarded by a factor of 200 at 1250°C by the doping of 0.1mol% Y3+ or Lu3+. We performed high-resolution transmission electron microscopy observations and chemical analysis by an energy dispersive X-ray spectrometer using an electron probe size of 1nm on samples of various kinds of cation-doped Al2O3s. The microstructure investigation revealed that the doped cations tend to segregate in the vicinity of the grain boundaries of the Al2O3; grain boundaries in the cation-doped Al2O3s are clean without any second phase particles or amorphous layer, and are essentially solid/solid boundaries. The segregation of the Y or Lu cations in the grain boundaries probably suppresses the grain boundary diffusion of Al2O3 and accordingly reduces the creep rate at high temperatures.

  2. Modelling the fine and coarse fraction of heavy metals in Spain

    NASA Astrophysics Data System (ADS)

    García Vivanco, Marta; González, M. Angeles

    2014-05-01

    Heavy metals, such as cadmium, lead, nickel, arsenic, copper, chrome, zinc and selenium, are present in the air due to natural and anthropogenic emissions, normally joined to particles. These metals can affect life organisms via inhalation or ingestion, causing damages in human health and ecosystems. Small particles are inhaled and embebed in lungs and alveolus more easily than coarse particles. The CHIMERE model is a eulerian air quality model extensively used in air quality modelling. Metals have been recently included in this model in a special version developed in the CIEMAT (Madrid, Spain) modelling group. Vivanco et al. (2011) and González et al. (2012) showed the model performance for some metals in Spain and Europe. However, in these studies, metals were considered as fine particles. Some studies based on observed heavy metals air concentration indicate the presence of metals also in the coarse fraction, in special for Cu and Zn. For this reason, a new attempt of modelling metals considering a fine (<2.5 micrometres) and coarse (2.5-10 micrometres) fraction has been done. Measurements of metal concentration in PM10, PM2.5 and PM1 recorded in Spain (Fernández-Camacho et al., 2012; Querol et al., 2008) were used to obtain the new metal particle distribution size. Results and the evaluation of the model performance at some minoring sites in Spain is presented. References: - Vivanco, M. G., M.A: González, I. Palomino, J. L. Garrido, X. Querol, B. Bessagnet, J.de la Rosa, A.M. Sánchez de la Campa, 2011. Modelling Arsenic, Lead, Cadmium and Nickel Ambient Air Concentrations in Spain, 2011. Proceedings of the 11 th International Conference on Computational Science and Its Applications (ICCSA 11) 243-246 - González, Ma Vivanco, Marta; Palomino, Inmaculada; Garrido, Juan; Santiago, Manuel; Bessagnet, Bertrand Modelling Some Heavy Metals Air Concentration in Europe. // Water, Air & Soil Pollution;Sep2012, Vol. 223 Issue 8, p5227

  3. Fine Mapping of a Grain-Weight Quantitative Trait Locus in the Pericentromeric Region of Rice Chromosome 3

    PubMed Central

    Li, Jiming; Thomson, Michael; McCouch, Susan R.

    2004-01-01

    As the basis for fine mapping of a grain-weight QTL, gw3.1, a set of near isogenic lines (NILs), was developed from an Oryza sativa, cv. Jefferson × O. rufipogon (IRGC105491) population based on five generations of backcrossing and seven generations of selfing. Despite the use of an interspecific cross for mapping and the pericentromeric location of the QTL, we observed no suppression of recombination and have been able to narrow down the location of the gene underlying this QTL to a 93.8-kb region. The locus was associated with transgressive variation for grain size and grain weight in this population and features prominently in many other inter- and intraspecific crosses of rice. The phenotype was difficult to evaluate due to the large amount of variance in size and weight among grains on a panicle and between grains on primary and secondary panicles, underscoring the value of using multiple approaches to phenotyping, including extreme sampling and NIL group-mean comparisons. The fact that a QTL for kernel size has also been identified in a homeologous region of maize chromosome 1 suggests that this locus, in which the dominant O. rufipogon allele confers small seed size, may be associated with domestication in cereals. PMID:15611185

  4. Shear Localization and its Related Microstructure Mechanism in a Fine-Grain-Sized Near-Beta Ti Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Bingfeng; Sun, Jieying; Hahn, Eric Nicholas; Wang, Xiaoyan

    2015-01-01

    Shear localization is an important deformation and failure mechanism for the high strength near beta fine-grain-sized titanium alloy used in aircraft's gear at high rate deformation. Hat-shaped specimens are used to induce the formation of an adiabatic shear band under controlled shock-loading tests. Unstable shear deformation of the alloy emerges after the true flow stress reaches 1147 MPa, the first vibration peak during the split Hopkinson pressure bar testing, and the whole process lasts about 68 μs. The microstructures within the shear band in the alloy are investigated by means of light microscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the grains in the boundary of the shear band are highly elongated along the shear direction, and the core of the shear band consists of ultrafine-equiaxed grains with diameters 0.1-0.3 μm, low dislocation density, and no observed phase transformation. The rotational dynamic recrystallization is used to explain the microstructural evolution mechanism in the shear band. Kinetic calculations indicate that the recrystallized ultrafine grains are formed during the deformation and do not undergo significant growth by grain boundary migration after deformation.

  5. Fluid distribution in grain boundaries of natural fine-grained rock salt deformed at low shear stress: implications for rheology and transport properties

    NASA Astrophysics Data System (ADS)

    Desbois, G.; Urai, J. L.; De Bresser, J. H. P.

    2012-04-01

    We used a combination of broad ion beam (BIB) cross-sectioning and high resolution (cryogenic) SEM to image polished surfaces and corresponding pairs of fractured grain boundaries in an investigation of grain boundary (GB) microstructures and fluid distribution in naturally deformed halite from a salt glacier (Kum Quh, central Iran). At the scale of observations, four types of fluid or gas filled grain boundaries can be distinguished: (1) straight boundaries with thick (up to 10 µm) GB tubes (2) straight boundaries with narrow (about 50 nm) GB tubes (3) wavy (tens of µm wavelength) GB with isolated inclusions of a few µm, and (4) wavy (µm wavelength) GB with small (µm) isolated inclusions. Grain boundary fluid inclusions can have three types of morphologies: the inclusion of Type 1 is intruded completely in one grain, inclusion of Type 2 has its major part included in one grain with a minor part in the second grain and the inclusion of Type 3 is located in both grains. Solid second phases in GB are mainly euhedral anhydrite crystals. The mobility of the brine is shown after cutting the inclusions by BIB in vacuum and fine-grained halite forms efflorescence and precipitates on internal walls of inclusions. At cryogenic temperature, in-situ brine is seen as continuous film in GB of type (1) and (2), and in isolated inclusions in GB of type (3) and (4). The structure of halite-halite contact between isolated fluid inclusions in GB of type (3) and (4) is below the resolution of SEM. GB of type (3) and (4) are interpreted to have formed by healing of mobile fluid films. First results of deformation experiments on the same samples under shear stress corresponding to conditions of natural salt glacier, show very low strain rates (7.43x10-10 s-1 and 1x10-9 s-1), up to one order of magnitude below of expected strain rates by solution precipitation creep. Both microstructures and deformation experiments suggest interfacial energy-driven GB healing, in agreement with the

  6. Grain-shape parameters for high-temperature creep resistance in powder metallurgy tungsten fine wires

    SciTech Connect

    Tanoue, K.

    1998-02-01

    Three grain-shape parameters, f{sub 1}, f{sub 2}, and f{sub 3}, are defined to clarify the morphological effect of grains on the high-temperature creep resistance under the condition that no grain boundary cavitation occurs. The parameter f{sub 1} is characteristic of complicated grain shapes, suggesting that it can be a measure of the interlocking grain structure. The parameter f{sub 2} is an important parameter when torsional stresses are imposed on coiled wires, and f{sub 3} is characteristic of the short-range roughness of grain boundaries only when f{sub 1} is not greatly changed. The minimum creep rate decreases as the grain aspect ratio, R, increases for R < 30, and the creep rate increases as R increases for R > 30. The parameter f{sub 1}, as well as Raj and Ashby`s model, gives a satisfactory explanation for the former behavior. On the other hand, it is proven that their model must be modified using f{sub 3} to explain the latter behavior because of the highly elongated grain configuration that is associated with R > 30.

  7. Distribution of Lipids in the Grain of Wheat (cv. Hereward) Determined by Lipidomic Analysis of Milling and Pearling Fractions.

    PubMed

    González-Thuillier, Irene; Salt, Louise; Chope, Gemma; Penson, Simon; Skeggs, Peter; Tosi, Paola; Powers, Stephen J; Ward, Jane L; Wilde, Peter; Shewry, Peter R; Haslam, Richard P

    2015-12-16

    Lipidomic analyses of milling and pearling fractions from wheat grain were carried out to determine differences in composition that could relate to the spatial distribution of lipids in the grain. Free fatty acids and triacylglycerols were major components in all fractions, but the relative contents of polar lipids varied, particularly those of lysophosphatidylcholine and digalactosyldiglyceride, which were enriched in flour fractions. By contrast, minor phospholipids were enriched in bran and offal fractions. The most abundant fatty acids in the analyzed acyl lipids were C16:0 and C18:2 and their combinations, including C36:4 and C34:2. Phospholipids and galactolipids have been reported to have beneficial properties for breadmaking, whereas free fatty acids and triacylglycerols are considered detrimental. The subtle differences in the compositions of fractions determined in the present study could therefore underpin the production of flour fractions with optimized compositions for different end uses.

  8. Fossil and Contemporary Fine Carbon Fractions at 12 Rural and Urban Sites in the United States

    SciTech Connect

    Schichtel, B; Malm, W; Bench, G; Fallon, S; McDade, C; Chow, J

    2007-03-01

    Fine particulate matter collected at two urban, four near-urban, and six remote sites throughout the United States were analyzed for total carbon (TC) and radiocarbon ({sup 14}C). Samples were collected at most sites for both a summer and winter season. The radiocarbon was used to partition the TC into fossil and contemporary fractions. On average, contemporary carbon composed about half of the carbon at the urban, {approx}70-97% at near-urban, and 82-100% at remote sites. At Phoenix, Arizona, and Seattle, Washington, one monitor was located within the urban center and one outside to assess the urban excess over background concentrations. During the summer the urban and rural sites had similar contemporary carbon concentrations. However, during the winter the urban sites had more than twice the contemporary carbon measured at the neighboring sites, indicating anthropogenic contributions to the contemporary carbon. The urban fossil carbon was 4-20 times larger than the neighboring rural sites for both seasons. Organic (OC) and elemental carbon (EC) from TOR analysis were available. These and the radiocarbon data were used to estimate characteristic fossil and contemporary EC/TC ratios for the winter and summer seasons. These ratios were applied to carbon data from the Interagency Monitoring of Protected Visual Environments network to estimate the fraction of contemporary carbon at mostly rural sites throughout the United States. In addition, the ratios were used to develop a semiquantitative, lower bound estimate of secondary organic carbon (SOC) contribution to fossil and contemporary carbon. SOC accounted for more than one-third of the fossil and contemporary carbon.

  9. Aerosol fine fraction in the Venice Lagoon: Particle composition and sources

    NASA Astrophysics Data System (ADS)

    Prodi, F.; Belosi, F.; Contini, D.; Santachiara, G.; Di Matteo, L.; Gambaro, A.; Donateo, A.; Cesari, D.

    2009-04-01

    The work presents a characterisation of aerosol sampled during three campaigns conducted in the Venice Lagoon from 30 June to 21 July 2004, from 15 February to 10 March 2005 and from 8 May to 25 May 2006. The results yield information about the physical-chemical characteristics of fine aerosol, the possible sources and its fate. Sulphate (SO 42-), nitrate (NO 3-) and ammonium (NH 4+) are identified as the main water soluble components. The sum of these ions in the spring campaign 2006 varies from 51% to nearly 100% of PM2.5 fraction aerosol. NH 4+ is found to be significantly correlated to non-sea-salt sulphate (nss-SO 42-) and NO 3-, thus indicating the prevalent presence of ammonium nitrate and sulphate. The overall lack of a clear diurnal and seasonal cycle of sulphate suggests a transport from the Po Valley, while the diurnal and seasonal profile of nitrate concentrations suggests a prevalence of local generation. Sulphates from sea water through oxidation of dimethylsulfide (DMS) are not negligible (about 10% of the anthropogenic sulphate). The marine aerosol contribution to PM1 and PM2.5 fractions, calculated using Na + as a tracer of sea-salts, is low (range 1-6%). In some cases chlorine depletion is observed. The content of chlorine in the aerosol particle is mostly higher than expected for marine environments (considered on the basis of Cl -/Na + ratio). Therefore, specific sources for the element have been suggested. Oxalic acid anion, which accounts for 55% of the organic compounds examined, presents mean values 180 ng m - 3 and 161 ng m - 3 in the winter and spring campaigns, comparable with reported values in low polluted urban areas. In the winter campaign there is a high correlation between formate and acetate ( R2 = 0.93), suggesting that a common source makes a high contribution to the measured concentrations.

  10. Hot deformation behavior of uniform fine-grained GH4720Li alloy based on its processing map

    NASA Astrophysics Data System (ADS)

    Yu, Qiu-ying; Yao, Zhi-hao; Dong, Jian-xin

    2016-01-01

    The hot deformation behavior of uniform fine-grained GH4720Li alloy was studied in the temperature range from 1040 to 1130°C and the strain-rate range from 0.005 to 0.5 s-1 using hot compression testing. Processing maps were constructed on the basis of compression data and a dynamic materials model. Considerable flow softening associated with superplasticity was observed at strain rates of 0.01 s-1 or lower. According to the processing map and observations of the microstructure, the uniform fine-grained microstructure remains intact at 1100°C or lower because of easily activated dynamic recrystallization (DRX), whereas obvious grain growth is observed at 1130°C. Metallurgical instabilities in the form of non-uniform microstructures under higher and lower Zener-Hollomon parameters are induced by local plastic flow and primary γ' local faster dissolution, respectively. The optimum processing conditions at all of the investigated strains are proposed as 1090-1130°C with 0.08-0.5 s-1 and 0.005-0.008 s-1 and 1040-1085°C with 0.005-0.06 s-1.

  11. Predicting the Fine Particle Fraction of Dry Powder Inhalers Using Artificial Neural Networks.

    PubMed

    Muddle, Joanna; Kirton, Stewart B; Parisini, Irene; Muddle, Andrew; Murnane, Darragh; Ali, Jogoth; Brown, Marc; Page, Clive; Forbes, Ben

    2017-01-01

    Dry powder inhalers are increasingly popular for delivering drugs to the lungs for the treatment of respiratory diseases, but are complex products with multivariate performance determinants. Heuristic product development guided by in vitro aerosol performance testing is a costly and time-consuming process. This study investigated the feasibility of using artificial neural networks (ANNs) to predict fine particle fraction (FPF) based on formulation device variables. Thirty-one ANN architectures were evaluated for their ability to predict experimentally determined FPF for a self-consistent dataset containing salmeterol xinafoate and salbutamol sulfate dry powder inhalers (237 experimental observations). Principal component analysis was used to identify inputs that significantly affected FPF. Orthogonal arrays (OAs) were used to design ANN architectures, optimized using the Taguchi method. The primary OA ANN r(2) values ranged between 0.46 and 0.90 and the secondary OA increased the r(2) values (0.53-0.93). The optimum ANN (9-4-1 architecture, average r(2) 0.92 ± 0.02) included active pharmaceutical ingredient, formulation, and device inputs identified by principal component analysis, which reflected the recognized importance and interdependency of these factors for orally inhaled product performance. The Taguchi method was effective at identifying successful architecture with the potential for development as a useful generic inhaler ANN model, although this would require much larger datasets and more variable inputs.

  12. Evidence of sealing and brine distribution at grain boundaries in natural fine-grained Halite (Qum Kuh salt fountain, Central Iran): implications for rheology of salt extrusions

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Urai, Janos L.; de Bresser, J. H. P.

    2010-05-01

    are expected for similar grain size ([5]). Other samples, which were loaded to 1 MPa before reducing the stress to 0.5 MPa deformed at much higher but variable rates, up to 10-8 s-1, in good agreement with activated PS creep. If, at first look, our pilot deformation experiments seem to reflect a kind of "yield stress" for activation PS creep ([7]); the experimental stress does not reach the theoritical condition to enable activation of PS. Thus, we interpret that the apparent "yielding stress" may not reflect strictu senso the "yielding stress" as described in [7] but rather to a "yielding stress" corresponding to the elastic reassessment of the grain system before the initiation of PS at privileged seal-brine-grain contacts. In salt fountain conditions, mylonitic samples are expected to be in the healing domain, but "jumps" in active stress required to activate PS creep is hardly probable. Thus, we suggest that rainwater influx plays a fundamental role in activation of PS. Rainwater should enable the marginal dissolution of healed contacts and then decreases in the area fraction of grain boundary occupied by solid island contact causing an increase in island stress. Therefore, this points to cyclic deformation of salt fountain: (1) during rainy periods the fountain will deformed at relative high strain rate by dominant PS; while (2) during dry seasons, it will not significantly flow because the grain boundary healing will prevent PS and lead to dominant dislocation creep. This interpretation is in good agreement with recent structural studies ([1], [4]), which gives evidence for both dynamic dislocation and pressure-solution creeps, and measurement of rapid flow after rainy periods with flow rates compatible with fully activated PS ([3]). [1] Desbois G., Zavada P., Schleder Z. and Urai J.L. (In review). Deformation and recrystallization mechanisms in naturally deformed salt fountain: microstructural evidence for a switch in deformation mechanisms with increased

  13. Kaempferol Identified by Zebrafish Assay and Fine Fractionations Strategy from Dysosma versipellis Inhibits Angiogenesis through VEGF and FGF Pathways.

    PubMed

    Liang, Fang; Han, Yuxiang; Gao, Hao; Xin, Shengchang; Chen, Shaodan; Wang, Nan; Qin, Wei; Zhong, Hanbing; Lin, Shuo; Yao, Xinsheng; Li, Song

    2015-10-08

    Natural products are a rich resource for the discovery of therapeutic substances. By directly using 504 fine fractions from isolated traditional Chinese medicine plants, we performed a transgenic zebrafish based screen for anti-angiogenesis substances. One fraction, DYVE-D3, was found to inhibit the growth of intersegmental vessels in the zebrafish vasculature. Bioassay-guided isolation of DYVE-D3 indicates that the flavonoid kaempferol was the active substance. Kaempferol also inhibited the proliferation and migration of HUVECs in vitro. Furthermore, we found that kaempferol suppressed angiogenesis through inhibiting VEGFR2 expression, which can be enhanced by FGF inhibition. In summary, this study shows that the construction of fine fraction libraries allows efficient identification of active substances from natural products.

  14. Dressing of fine grained diamond grinding wheels for ultra precision grinding of structured molds in brittle hard materials

    NASA Astrophysics Data System (ADS)

    Bletek, Thomas; Klocke, Fritz; Hünten, Martin; Dambon, Olaf

    2013-09-01

    The manufacturing of structured molds calls for alternatives in terms of grinding wheel geometry and dressing. To manufacture geometric features in the micron range on molds, sharp edged fine grained grinding wheels can be used. A dressing procedure with metal alloy blocks is used to create sharp edged grinding wheels. This paper presents results and achieved tip radii of dressed resin bonded and metal bonded grinding wheels. Furthermore, a grinding test on a tungsten carbide mold is carried out to create a diffractive structure and the achieved form accuracy and surface roughness are presented.

  15. Pore-Scale Controls on Permeability, Fluid Flow, and Methane Hydrate Distribution in Fine-Grained Sediments

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh Callahan

    2011-12-01

    Permeability in fine-grained sediments is governed by the surface area exposed to fluid flow and tortuosity of the pore network. I modify an existing technique of computing permeability from nuclear magnetic resonance (NMR) data to extend its applicability beyond reservoir-quality rocks to the fine-grained sediments that comprise the majority of the sedimentary column. This modification involves correcting the NMR data to account for the large surface areas and disparate mineralogies typically exhibited by fine-grained sediments. Through measurements on resedimented samples composed of controlled mineralogies, I show that this modified NMR permeability algorithm accurately predicts permeability over 5 orders of magnitude. This work highlights the importance of pore system surface area and geometry in determining transport properties of porous media. I use these insights to probe the pore-scale controls on methane hydrate distribution and hydraulic fracturing behavior, both of which are controlled by flux and permeability. To do this I employ coupled poromechanical models of hydrate formation in marine sediments. Fracture-hosted methane hydrate deposits are found at many sites worldwide, and I investigate whether pore occlusion and permeability reduction due to hydrate formation can drive port fluid pressures to the point at which the sediments fracture hydraulically. I find that hydraulic fractures may form in systems with high flux and/or low permeability; that low-permeability layers can influence the location of fracture initiation if they are thicker than a critical value that is a function of flux and layer permeability; that capillary-driven depression of the triple point of methane in fine-gained sediments causes hydrate to form preferentially in coarse-grained layers; that the relative fluxes of gas and water in multiphase systems controls hydrate distribution and the location of fracture initiation; and that methane hydrate systems are dynamic systems in

  16. Distribution and leaching ability of some heavy metals in products of flotation processing of fine-grained coal slurries

    SciTech Connect

    Klika, Z.; Weiss, Z.; Lach, K.

    1994-12-31

    Coal from the Ostrava-Karvina mines is processed in 19 coal preparation plants, 6 of which are not equipped with flotation technology. Generally, all fine-grained coal is transported into sedimentary coal slurry ponds. Depending on processing technology, coal slurries contain from 5 to 95% coal matter. Sedimentary coal slurry ponds occupy large areas, deteriorate the landscape, and ar great sources of dust in a dry summer. Moreover, some components from coal slurries scan be leached and can penetrate into underground water. This research project sampled 13 coal slurry ponds to determine the composition of coal slurries, the distribution of some heavy metals in the flotation process, and leaching behavior.

  17. The enigma of fine-grained alluvial basin fills: the Permo-Triassic (Cumbrian Coastal and Sherwood Sandstone Groups) of the Solway Basin, NW England and SW Scotland)

    NASA Astrophysics Data System (ADS)

    Brookfield, Michael E.

    The late Permian to Triassic sediments of the Solway Basin consist of a layer-cake succession of mature, predominantly fine-grained red clastics laid down in semi-arid alluvial plain to arid sabkha and saline marginal marine or lacustrine environments. The Cumbrian Coastal Group consists of Basal Clastics and Eden Shales. The Basal Clastics are thin regolith deposits resting unconformably on all-underlying units and are composed of mixtures of angular local gravel and far-transported fine to very fine-grained sands deposited as basal lag. The Eden Shales are predominantly gypsiferous red silty mudstones, with thin very fine-grained sandstone beds, and with thick marine gypsum beds at the base, deposited at a saline lake margin. The overlying Triassic Sherwood Sandstone Group consists of the Annan and Kirklinton Sandstones. The Annan Sandstones are predominantly thick-bedded, multi-storied, fine-grained mature red quartz sandstones in which coarse sand is practically absent despite channels with clay pebbles up to 30 cm in diameter. The overlying, predominantly aeolian, Kirklinton Sandstones consist of festoon cross-bedded and parallel-laminated fine-grained sandstones, almost identical to the Annan Sandstones except that mica and clay are absent. The Stanwix Shales, located above, consist of interbedded red, blue and green mudstones, siltstones, and thin very fine-grained sandstones, with gypsum layers. Although the entire succession can plausibly be interpreted as deposited in a large desert basin opening into a hypersaline marine or lacustrine embayment to the southwest, the uniformly fine-grained nature of the succession is unusual, as is the absence of paleosols, and body and trace fossils. There is almost no coarse sand even in the river channel units, and it seems likely that the basin was not only extremely arid but supplied predominantly by wind rather than water.

  18. Rare earth and major element geochemistry of Eocene fine-grained sediments in oil shale- and coal-bearing layers of the Meihe Basin, Northeast China

    NASA Astrophysics Data System (ADS)

    Bai, Yueyue; Liu, Zhaojun; Sun, Pingchang; Liu, Rong; Hu, Xiaofeng; Zhao, Hanqing; Xu, Yinbo

    2015-01-01

    rather than by organic matter. In both layers, REEs have no relationship with fine-grained phosphates, and during the weathering process, the REEs were not very mobile and were resistant to fractionation.

  19. Characterization of ultra-fine grained aluminum produced by accumulative back extrusion (ABE)

    SciTech Connect

    Alihosseini, H.; Faraji, G.; Dizaji, A.F.; Dehghani, K.

    2012-06-15

    In the present work, the microstructural evolutions and microhardness of AA1050 subjected to one, two and three passes of accumulative back extrusion (ABE) were investigated. The microstructural evolutions were characterized using transmission electron microscopy. The results revealed that applying three passes of accumulative back extrusion led to significant grain refinement. The initial grain size of 47 {mu}m was refined to the grains of 500 nm after three passes of ABE. Increasing the number of passes resulted in more decrease in grain size, better microstructure homogeneity and increase in the microhardness. The cross-section of ABEed specimen consisted of two different zones: (i) shear deformation zone, and (ii) normal deformation zone. The microhardness measurements indicated that the hardness increased from the initial value of 31 Hv to 67 Hv, verifying the significant microstructural refinement via accumulative back extrusion. - Highlights: Black-Right-Pointing-Pointer A significant grain refinement can be achieved in AA1050, Al alloy by applying ABE. Black-Right-Pointing-Pointer Microstructural homogeneity of ABEed samples increased by increasing the number of ABE cycles. Black-Right-Pointing-Pointer A substantial increase in the hardness, from 31 Hv to 67 Hv, was recorded.

  20. Effect of partial recrystallization on the grain size and grain boundary structure of austenitic steel

    SciTech Connect

    Szabo, Peter J.

    2012-04-15

    Cyclic thermomechanical treatment combined with caliber rolling was applied in order to obtain very fine grain structure with high fraction of special grain boundaries in austenitic stainless steel. Partial recrystallization was observed. Recrystallized fraction was assessed from misorientation data measured by electron back scattering diffraction. Due to the partial recrystallization, elastic energy was stored in the deformed parts, and helped grain boundary movement. As a consequence, very fine grained material with high fraction of special boundaries was formed. - Highlights: Black-Right-Pointing-Pointer I combined the advantage of severe plastic deformation and thermomechanical treatment. Black-Right-Pointing-Pointer A very fine grained steel with high fraction of special boundaries was formed. Black-Right-Pointing-Pointer Stored elastic energy hepled the movement of grain boundaries. Black-Right-Pointing-Pointer The amount of recrystallized part was determined by EBSD.

  1. Interactions between fine-grained sediment delivery, river bed deposition and salmonid spawning success

    NASA Astrophysics Data System (ADS)

    Pattison, I.; Sear, D. A.; Collins, A. L.; Jones, J. I.; Naden, P. S.

    2015-03-01

    Salmonids clean river bed gravels to lay their eggs. However, during the incubation period fine sediment infiltrates the bed. This has been found to limit the success of salmonid spawning, as fine sediment reduces gravel permeability resulting in intra-gravel flow velocities and O2 concentrations decreasing. The success of salmonid spawning is therefore a function of the coincidence of fine sediment delivery and the development of the salmonid eggs. The presence of fine sediment also exerts sub-lethal effects on the rate of egg development with a negative feedback slowing and extending the incubation process meaning the eggs are in the gravels for longer and susceptible to more potential sediment delivery events. The SIDO (Sediment Intrusion and Dissolved Oxygen)-UK model is a physically-based numerical model which simulates the effect of fine sediment deposition on the abiotic characteristics of the salmonid redd, along with the consequences for egg development and survival. This model is used to investigate the interactions and feedbacks between the timing and concentrations of suspended sediment delivery events, and the deposition of fine sediment within the gravel bed, and the consequences of this on the rate of egg development and survival. The model simulations suggest that egg survival is highly sensitive to suspended sediment concentrations, particularly to changes in the supply rate of sand particles. The magnitude, frequency and specific timing of sediment delivery events effects egg survival rates. The modelling framework is also used to investigate the impact of the rate of gravel infilling by sediment. The hypotheses of continual, discrete event and non-linear decline in the rate of infilling are investigated.

  2. Concentrations and Distribution of Slag-Related Trace Elements and Mercury in Fine-Grained Beach and Bed Sediments of Lake Roosevelt, Washington, April-May 2001

    USGS Publications Warehouse

    Majewski, Michael S.; Kahle, Sue C.; Ebbert, James C.; Josberger, Edward G.

    2003-01-01

    A series of studies have documented elevated concentrations of trace elements such as arsenic, cadmium, copper, lead, mercury, and zinc in the water, bed sediment, or fish of Lake Roosevelt and the upstream reach of the Columbia River. Elevated concentrations of some trace elements in this region are largely attributable to the transport of slag and metallurgical waste discharged into the Columbia River from a smelter in Canada. Although most recent studies have focused on contamination levels in water, bed sediment, and fish, there is growing concern in the region over the potential threat of airborne contaminants to human health. In response to these concerns, the U.S. Geological Survey conducted an assessment of trace-element concentrations in the relatively shallow fine-grained sediment along the shore of Lake Roosevelt that is exposed annually during periods of reservoir drawdown. During each winter and spring, the water level of Lake Roosevelt is lowered as much as about 80 feet to provide space to capture high river flows from spring runoff, exposing vast expanses of lake-bottom sediment for a period of several months. Upon drying, these exposed areas provide an extremely large source for wind-blown dust. This study concluded that trace elements associated with slag and metallurgical waste are present in the fine-grained fraction (less than 63 micrometers) of bed sediments along the length of Lake Roosevelt, and as such, could be components of the airborne dust resulting from exposure, drying, and wind mobilization of the sediments exposed during the annual drawdowns of the reservoir. Trace-element concentrations in the surficial bed sediment varied, but the major components in slag?arsenic, cadmium, copper, lead, and zinc?showed generally pronounced gradients of decreasing concentrations from near the International Border to the Grand Coulee Dam. The results of this study provide base-line information needed to plan and conduct air monitoring of trace

  3. Evaluation of a Non-Nuclear Soil Density Gauge on Fine-Grained Soils

    DTIC Science & Technology

    2013-05-01

    U.S. STANDARD SIEVE NUMBERS HYDROMETER fY, in o/. in. 318 in #140 6 in. 3 in. 2 in. 1 in. ’A in #4 ’" #20 #30 #40 ឬ #100 #200 100 J I ’ I I I I I...1 3-20 31 C L-2 U.S. SIEVE OPENING IN INCHES U.S. STANDARD SIEVE NUMBERS HYDROMETER 1Y,in. ’/.in Un~/8 in #140 6 in 3 in. 2 in. 1in. " #4...Particle Size Distribution Reoort Fine PL 14 HYDROMETER %Fines Silt -------,---- PI Project Non-Nuclear Gau_ge Proiect 27 Area Boring No. 3 Date

  4. Composite fermions and the first-Landau-level fine structure of the fractional quantum Hall effect

    NASA Astrophysics Data System (ADS)

    Haxton, W. C.; Haxton, Daniel J.

    2016-04-01

    A set of scalar operators, originally introduced in connection with an analytic first-Landau-level (FLL) construction of fractional quantum Hall (FQHE) wave functions for the sphere, are employed in a somewhat different way to generate explicit representations of both hierarchy states (e.g., the series of fillings ν =1 /3 , 2/5, 3/7,⋯) and their conjugates (ν =1 , 2/3, 3/5,⋯) as noninteracting quasielectrons filling fine-structure subshells within the FLL. This yields, for planar and spherical geometries, a quasielectron representation of the incompressible FLL state of filling p /(2 p +1 ) in a magnetic field of strength B that is algebraically identical to the IQHE state of filling ν =p in a magnetic field of strength B /(2 p +1 ) . The construction provides a precise definition of the quasielectron/composite fermion that differs in some respects from common descriptions: they are eigenstates of L ,Lz ; they and the FLL subshells they occupy carry a third index I that is associated with breaking of scalar pairs; they absorb in their internal wave functions one, not two, units of magnetic flux; and they share a common, simple structure as vector products of a spinor creating an electron and one creating magnetic flux. We argue that these properties are a consequence of the breaking of the degeneracy of noninteracting electrons within the FLL by the scale-invariant Coulomb potential. We discuss the sense in which the wave function construction supports basic ideas of both composite fermion and hierarchical descriptions of the FQHE. We describe symmetries of the quasielectrons in the ν =1 /2 limit, where a deep Fermi sea of quasielectrons forms, and the quasielectrons take on Majorana and pseudo-Dirac characters. Finally, we show that the wave functions can be viewed as fermionic excitations of the bosonic half-filled shell, producing at ν =1 /2 an operator that differs from but plays the same role as the Pfaffian.

  5. Petrology of a fine-grained igneous rock from the sea of tranquillity.

    PubMed

    Weill, D F; McCallum, I S; Bottinga, Y; Drake, M J; McKay, G A

    1970-01-30

    All phases in a thin section of sample 10022 have been analyzed by electron microprobe. Augite grains show strong iron enrichment in the outer 15 to 20 microns. Pigeonite cores occur within augite grains. The plagioclase has an anorthite content of between 73 and 81 mole percent and is high in Si and low in Al compared to stoichiometric feldspar. Residual phases include microcrystalline Fe-rich "pyroxene," plagioclase, K-rich alkali feldspar, silica, and rare areas rich in P and Zr with concentrations of Ba, Y, and rare earth elements. The density, viscosity, and crystallization history of the lava of sample 10022 are discussed.

  6. A high-speed multiplexer-based fine-grain pipelined architecture for digital fuzzy logic controllers

    NASA Astrophysics Data System (ADS)

    Rashidi, Bahram; Masoud Sayedi, Sayed

    2015-12-01

    Design and implementation of a high-speed multiplexer-based fine-grain pipelined architecture for a general digital fuzzy logic controller has been presented. All the operators have been designed at gate level. For the multiplication, a multiplexer-based modified Wallace tree multiplier has been designed, and for the division and addition multiplexer-based non-restoring parallel divider and multiplexer-based Manchester adder have been used, respectively. To further increase the processing speed, fine-grain pipelining technique has been employed. By using this technique, the critical path of the circuit is broken into finer pieces. Based on the proposed architecture, and by using Quartus II 9.1, a sample two-input, one-output digital fuzzy logic controller with eight rules has been successfully synthesised and implemented on Stratix II field programmable gate array. Simulations were carried out using DSP Builder in the MATLAB/Simulink tool at a maximum clock rate of 301.84 MHz.

  7. Ultra-Fine Grain Structures Of Model Al-Mg-Si Alloys Produced By Hydrostatic Extrusion

    NASA Astrophysics Data System (ADS)

    Adamczyk-Cieślak, Bogusława; Mizera, Jarosław

    2011-01-01

    Microstructure and mechanical properties were studied in model Al-Mg-Si alloys (Al-1 % Mg-0.8% Si and Al-0.5% Mg-0.3% Si-wt %) deformed by hydrostatic extrusion (HE) to strains of 1.4 and 3.8. In these alloys the different percentage of two hardening second-phase precipitates (Mg2Si and Si) were observed. The microstructure was characterized by transmission electron microscopy and optical microscopy. The microstructure of the alloys in the initial state was built of coarse grains of an average diameter of ˜30 rim. The refined microstructure was examined qualitatively and quantitatively using the stereological method and a computer image analysis. The deformation-processed structures evolved very rapidly, forming ultrafine grained (UFG) materials with grains of about 0.4 μm. In addition, the grain refinement in the HE-treated materials has a substantial effect on their properties, such as the mechanical strength and micro-hardness which increase significantly. It has been found that, after ɛ = 3.8 in the Al-1% Mg-0.8% Si alloy, the micro-hardness increases approximately twofold. The yield stress is more than four times higher in the UFG alloys, in comparison to the initial state. Similar results were identified in the Al-0.5% Mg-0.3% Si. This is due to the very rapid refinement of the microstructure during the deformation and presence of second-phase particles.

  8. Ultra-Fine Grain Structures Of Model Al-Mg-Si Alloys Produced By Hydrostatic Extrusion

    SciTech Connect

    Adamczyk-Cieslak, Boguslawa; Mizera, Jaroslaw

    2011-01-17

    Microstructure and mechanical properties were studied in model Al-Mg-Si alloys (Al-1 % Mg-0.8% Si and Al-0.5% Mg-0.3% Si-wt %) deformed by hydrostatic extrusion (HE) to strains of 1.4 and 3.8. In these alloys the different percentage of two hardening second-phase precipitates (Mg{sub 2}Si and Si) were observed. The microstructure was characterized by transmission electron microscopy and optical microscopy. The microstructure of the alloys in the initial state was built of coarse grains of an average diameter of {approx}30 rim. The refined microstructure was examined qualitatively and quantitatively using the stereological method and a computer image analysis. The deformation-processed structures evolved very rapidly, forming ultrafine grained (UFG) materials with grains of about 0.4 {mu}m. In addition, the grain refinement in the HE-treated materials has a substantial effect on their properties, such as the mechanical strength and micro-hardness which increase significantly. It has been found that, after {epsilon} = 3.8 in the Al-1% Mg-0.8% Si alloy, the micro-hardness increases approximately twofold. The yield stress is more than four times higher in the UFG alloys, in comparison to the initial state. Similar results were identified in the Al-0.5% Mg-0.3% Si. This is due to the very rapid refinement of the microstructure during the deformation and presence of second-phase particles.

  9. Effects of coarse grain size distribution and fine particle content on pore fluid pressure and shear behavior in experimental debris flows

    NASA Astrophysics Data System (ADS)

    Kaitna, Roland; Palucis, Marisa C.; Yohannes, Bereket; Hill, Kimberly M.; Dietrich, William E.

    2016-02-01

    Debris flows are typically a saturated mixture of poorly sorted particles and interstitial fluid, whose density and flow properties depend strongly on the presence of suspended fine sediment. Recent research suggests that grain size distribution (GSD) influences excess pore pressures (i.e., pressure in excess of predicted hydrostatic pressure), which in turn plays a governing role in debris flow behaviors. We report a series of controlled laboratory experiments in a 4 m diameter vertically rotating drum where the coarse particle size distribution and the content of fine particles were varied independently. We measured basal pore fluid pressures, pore fluid pressure profiles (using novel sensor probes), velocity profiles, and longitudinal profiles of the flow height. Excess pore fluid pressure was significant for mixtures with high fines fraction. Such flows exhibited lower values for their bulk flow resistance (as measured by surface slope of the flow), had damped fluctuations of normalized fluid pressure and normal stress, and had velocity profiles where the shear was concentrated at the base of the flow. These effects were most pronounced in flows with a wide coarse GSD distribution. Sustained excess fluid pressure occurred during flow and after cessation of motion. Various mechanisms may cause dilation and contraction of the flows, and we propose that the sustained excess fluid pressures during flow and once the flow has stopped may arise from hindered particle settling and yield strength of the fluid, resulting in transfer of particle weight to the fluid. Thus, debris flow behavior may be strongly influenced by sustained excess fluid pressures controlled by particle settling rates.

  10. XRD-based 40Ar/39Ar age correction for fine-grained illite, with application to folded carbonates in the Monterrey Salient (northern Mexico)

    NASA Astrophysics Data System (ADS)

    Fitz-Díaz, Elisa; Hall, Chris M.; van der Pluijm, Ben A.

    2016-05-01

    Due to their minute size, 40Ar/39Ar analysis of illite faces significant analytical challenges, including mineral characterization and, especially, effects of grain size and crystallography on 39Ar recoil. Quantifying the effects of 39Ar recoil requires the use of sample vacuum encapsulation during irradiation, which permits the measurement of the fraction of recoiled 39Ar as well as the 39Ar and 40Ar∗ retained within illite crystals that are released during step heating. Total-Gas Ages (TGA) are calculated by using both recoiled and retained argon, which is functionally equivalent to K-Ar ages, while Retention Ages (RA) only involve retained Ar in the crystal. Natural applications have shown that TGA fits stratigraphic constraints of geological processes when the average illite crystallite thickness (ICT) is smaller than 10 nm, and that RA matches these constraints for ICTs larger than 50 nm. We propose a new age correction method that takes into account the average ICT and corresponding recoiled 39Ar for a sample, with X-ray Corrected Ages (XCA) lying between Total-Gas and Retention Ages depending on ICT. This correction is particularly useful in samples containing authigenic illite formed in the anchizone, with typical ICT values between 10 and 50 nm. In three samples containing authigenic illite from Cretaceous carbonates in the Monterrey Salient in northern Mexico, there is a range in TGAs among the different size-fractions of 46-49, 36-43 and 40-52 Ma, while RAs range from 54-64, 47-52 and 53-54 Ma, respectively. XCA calculations produce tighter age ranges for these samples of 52.5-56, 45.5-48.5 and 49-52.5 Ma, respectively. In an apparent age vs ICT or %2M 1illite plot, authigenic illite grains show a slope that is in general slightly positive for TGA, slightly negative for RA, but close to zero for XCA, with thinner crystallites showing more dispersion than thicker ones. In order to test if dispersion is due to a different formation history or the result

  11. Evaluation of Rock Powdering Methods to Obtain Fine-grained Samples for CHEMIN, a Combined XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Chipera, S. J.; Vaniman, D. T.; Bish, D. L.; Sarrazin, P.; Feldman, S.; Blake, D. F.; Bearman, G.; Bar-Cohen, Y.

    2004-01-01

    A miniature XRD/XRF (X-ray diffraction / X-ray fluorescence) instrument, CHEMIN, is currently being developed for definitive mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed to enable remote XRD analysis is how best to obtain a representative sample powder for analysis. For powder XRD analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a two-dimensional detector as used in the CHEMIN instrument will produce good results even with poorly prepared powder, the quality of the data will improve and the time required for data collection will be reduced if the sample is fine-grained and randomly oriented. A variety of methods have been proposed for XRD sample preparation. Chipera et al. presented grain size distributions and XRD results from powders generated with an Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL. The USDC was shown to be an effective instrument for sampling rock to produce powder suitable for XRD. In this paper, we compare powder prepared using the USDC with powder obtained with a miniaturized rock crusher developed at JPL and with powder obtained with a rotary tungsten carbide bit to powders obtained from a laboratory bench-scale Retsch mill (provides benchmark mineralogical data). These comparisons will allow assessment of the suitability of these methods for analysis by an XRD/XRF instrument such as CHEMIN.

  12. Evaluation of rock powdering methods to obtain fine-grained samples for CHEMIN, a combined XRD/XRF instrument

    SciTech Connect

    Chipera, S. J.; Vaniman, D. T.; Bish, D. L.; Sarrazin, P.; Feldman, S.; Blake, D.; Bearman, G. H.; Bar-Cohen, Yoseph

    2004-01-01

    A miniature XRD/XRD (X-ray diffraction/X-ray fluorescence) instrument, CHEMIN, is currently being developed for definite mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed to enable remote XRD analysis is how best to obtain a representative sample powder for analysis. For powder XRD analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a two-dimensional detector as used in the CHEMIN instrument produces good results even with poorly prepared powder, the quality of the data improves and the time required for data collection is reduced if the sample is fine-grained and randomly oriented. A variety of methods have been proposed for XRD sample preparation. Chipera et al. presented grain size distributions and XRD reuslts from powders generated with an Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL. The USDC was shown to be an effective instrument for sampling rock to produce powder suitable for XRD. In this paper, they compare powder prepared using the USDC with powder obtained with a miniaturized rock crusher developed at JPL and with powder obtained with a rotary tungsten carbide bit to powders obtained from a laboratory bench-scale Retsch mill (provides benchmark mineralogical data). These comparisons will allow assessment of the suitability of these methods for analysis by an XRD/XRD instrument such as CHEMIN.

  13. Surface morphology changes and deuterium retention in Toughened, Fine-grained Recrystallized Tungsten under high-flux irradiation conditions

    NASA Astrophysics Data System (ADS)

    Oya, M.; Lee, H. T.; Ueda, Y.; Kurishita, H.; Oyaidzu, M.; Hayashi, T.; Yoshida, N.; Morgan, T. W.; De Temmerman, G.

    2015-08-01

    Surface morphology changes and deuterium (D) retention in Toughened, Fine-Grained Recrystallized Tungsten (TFGR W) with TaC dispersoids (W-TaC) and pure tungsten exposed to D plasmas to a fluence of 1026 D/m2 s were studied as a function of the D ion flux (1022-1024 D/m2 s). As the flux increased from 1022 D/m2 s to 1024 D/m2 s, the numbers of blisters increased for both materials. However, smaller blisters were observed on W-TaC compared to pure W. In W-TaC, cracks beneath the surface along grain boundaries were observed, which were comparable to the blister sizes. The reason for the smaller blister sizes may arise from smaller grain sizes of W-TaC. In addition, reduction of the D retention in W-TaC was observed for higher flux exposures. D depth profiles indicate this reduction arises due to decrease in trapping in the bulk.

  14. Possible Gems and Ultra-Fine Grained Polyphase Units in Comet Wild 2.

    NASA Technical Reports Server (NTRS)

    Gainsforth, Z.; Butterworth, A. L.; Jilly-Rehak, C. E.; Westphal, A. J.; Brownlee, D. E.; Joswiak, D.; Ogliore, R. C.; Zolensky, M. E.; Bechtel, H. A.; Ebel, D. S.; Huss, G. R.; Sandford, S. A.; White, A. J.

    2016-01-01

    GEMS and ultrafine grained polyphase units (UFG-PU) in anhydrous IDPs are probably some of the most primitive materials in the solar system. UFG-PUs contain nanocrystalline silicates, oxides, metals and sulfides. GEMS are rounded approximately 100 nm across amorphous silicates containing embedded iron-nickel metal grains and sulfides. GEMS are one of the most abundant constituents in some anhydrous CPIDPs, often accounting for half the material or more. When NASA's Stardust mission returned with samples from comet Wild 2 in 2006, it was thought that UFG-PUs and GEMS would be among the most abundant materials found. However, possibly because of heating during the capture process in aerogel, neither GEMS nor UFG-PUs have been clearly found.

  15. Stabilization of fine fraction from landfill mining in anaerobic and aerobic laboratory leach bed reactors.

    PubMed

    Mönkäre, Tiina J; Palmroth, Marja R T; Rintala, Jukka A

    2015-11-01

    Fine fraction (FF, <20 mm) from mined landfill was stabilized in four laboratory-scale leach bed reactors (LBR) over 180 days. The aim was to study feasibility of biotechnological methods to treat FF and if further stabilization of FF is possible. Four different stabilization methods were compared and their effects upon quality of FF were evaluated. Also during the stabilization experiment, leachate quality as well as gas composition and quantity were analyzed. The methods studied included three anaerobic LBRs (one without water addition, one with water addition, and one with leachate recirculation) and one aerobic LBR (with water addition). During the experiment, the most methane was produced in anaerobic LBR without water addition (18.0 L CH4/kg VS), while water addition and leachate recirculation depressed methane production slightly, to 16.1 and 16.4 L CH4/kg VS, respectively. Organic matter was also removed via the leachate and was measured as chemical oxygen demand (COD). Calculated removal of organic matter in gas and leachate was highest in LBR with water addition (59 g COD/kg VS), compared with LBR without water addition or with leachate recirculation (51 g COD/kg VS). Concentrations of COD, ammonium nitrogen and anions in leachate decreased during the experiment, indicating washout mechanism caused by water additions. Aeration increased sulfate and nitrate concentrations in leachate due to oxidized sulfide and ammonium. Molecular weight distributions of leachates showed that all the size categories decreased, especially low molecular weight compounds, which were reduced the most. Aerobic stabilization resulted in the lowest final VS/TS (13.1%), lowest respiration activity (0.9-1.2 mg O2/g TS), and lowest methane production after treatment (0.0-0.8 L CH4/kg VS), with 29% of VS being removed from FF. Anaerobic stabilization methods also reduced organic matter by 9-20% compared with the initial amount. Stabilization reduced the quantity of soluble nitrogen

  16. Screening biological methods for laboratory scale stabilization of fine fraction from landfill mining.

    PubMed

    Mönkäre, Tiina J; Palmroth, Marja R T; Rintala, Jukka A

    2017-02-01

    Increasing interest for the landfill mining and the amount of fine fraction (FF) in landfills (40-70% (w/w) of landfill content) mean that sustainable treatment and utilization methods for FF are needed. For this study FF (<20mm) was mined from a municipal solid waste (MSW) landfill operated from 1967 to 1989. FF, which resembles soil, was stabilized in laboratory scale reactors in two phases: first, anaerobically for 101days and second, for 72days using four different methods: anaerobic with the addition of moisture (water) or inoculum (sewage sludge) and aerobic with continuous water washing, with, or without, bulking material. The aim was to evaluate the effect on the stability of mined FF, which has been rarely reported, and to study the quality and quantity of gas and leachate produced during the stabilization experiment. The study showed that aerobic treatment reduced respiration activity (final values 0.9-1.1mgO2/gTS) and residual methane potential (1.1LCH4/kgTS) better than anaerobic methods (1.8-2.3mg O2/g TS and 1.3-2.4L CH4/kg TS, respectively). Bulking material mixed in FF in one aerobic reactor had no effect on the stability of FF. The benefit of anaerobic treatment was the production of methane, which could be utilized as energy. Even though the inoculum addition increased methane production from FF about 30%, but the methane production was still relatively low (in total 1.5-1.7L CH4/kg TS). Continuous water washing was essential to remove leachable organic matter and soluble nutrients from FF, while increasing the volume of leachate collected. In the aerobic treatment, nitrogen was oxidized into nitrite and nitrate and then washed out in the leachate. Both anaerobic and aerobic methods could be used for FF stabilization. The use of FF, in landscaping for example, is possible because its nutrient content (4gN/kg TS and 1g P/kg TS) can increase the nutrient content of soil, but this may have limitations due to the possible presence of heavy metal and

  17. A reanalysis of MODIS fine mode fraction over ocean using OMI and daily GOCART simulations

    NASA Astrophysics Data System (ADS)

    Jones, T. A.; Christopher, S. A.

    2011-06-01

    Using daily Goddard Chemistry Aerosol Radiation and Transport (GOCART) model simulations and columnar retrievals of 0.55 μm aerosol optical thickness (AOT) and fine mode fraction (FMF) from the Moderate Resolution Imaging Spectroradiometer (MODIS), we estimate the satellite-derived aerosol properties over the global oceans between June 2006 and May 2007 due to black carbon (BC), organic carbon (OC), dust (DU), sea-salt (SS), and sulfate (SU) components. Using Aqua-MODIS aerosol properties embedded in the CERES-SSF product, we find that the mean MODIS FMF values for each aerosol type are SS: 0.31 ± 0.09, DU: 0.49 ± 0.13, SU: 0.77 ± 0.16, and (BC + OC): 0.80 ± 0.16. We further combine information from the ultraviolet spectrum using the Ozone Monitoring Instrument (OMI) onboard the Aura satellite to improve the classification process, since dust and carbonate aerosols have positive Aerosol Index (AI) values >0.5 while other aerosol types have near zero values. By combining MODIS and OMI datasets, we were able to identify and remove data in the SU, OC, and BC regions that were not associated with those aerosol types. The same methods used to estimate aerosol size characteristics from MODIS data within the CERES-SSF product were applied to Level 2 (L2) MODIS aerosol data from both Terra and Aqua satellites for the same time period. As expected, FMF estimates from L2 Aqua data agreed well with the CERES-SSF dataset from Aqua. However, the FMF estimate for DU from Terra data was significantly lower (0.37 vs. 0.49) indicating that sensor calibration, sampling differences, and/or diurnal changes in DU aerosol size characteristics were occurring. Differences for other aerosol types were generally smaller. Sensitivity studies show that a difference of 0.1 in the estimate of the anthropogenic component of FMF produces a corresponding change of 0.2 in the anthropogenic component of AOT (assuming a unit value of AOT). This uncertainty would then be passed along to any

  18. A reanalysis of MODIS fine mode fraction over ocean using OMI and daily GOCART simulations

    NASA Astrophysics Data System (ADS)

    Jones, T. A.; Christopher, S. A.

    2010-12-01

    Using daily Goddard Chemistry Aerosol Radiation and Transport (GOCART) model simulations and columnar retrievals of 0.55 μm aerosol optical thickness (AOT) and fine mode fraction (FMF) from the Moderate Resolution Imaging Spectroradiometer (MODIS), we estimate the aerosol concentration and particle size over the global oceans between June 2006 and May 2007 due to black carbon (BC), organic carbon (OC), dust (DU), sea-salt (SS), and sulfate (SU) components. Using Aqua-MODIS aerosol properties embedded in the CERES-SSF product, we find that the mean MODIS FMF values are SS: 0.31±0.09, DU: 0.49±0.13, SU: 0.77±0.16, and (BC+OC):0.80±0.16. We further combine information from the ultraviolet spectrum using the Ozone Monitoring Instrument (OMI) onboard the Aura satellite to improve the classification process, since dust and carbonaceous aerosols have positive Aerosol Index (AI) values >0.5 while other aerosol types have near zero values. By combining MODIS and OMI datasets, we were able to identify and remove data in the SU and CC regions that were not associated with those aerosol types. The same methods used to estimate aerosol size characteristics from MODIS data within the CERES-SSF product were also applied to Level 2 (L2) MODIS aerosol data from both Terra and Aqua satellites for the same time period. As expected, FMF estimates from L2 Aqua data agreed well with the CERES-SSF dataset, also from Aqua. However, the FMF estimate for DU from Terra data was significantly lower (0.37 vs. 0.49) indicating that sensor calibration, sampling differences and/or diurnal changes in DU aerosol size characteristics were occurring. Differences for other aerosol types were generally smaller. Sensitivity studies show that a difference of 0.1 in the estimate of the anthropogenic component of FMF produces a corresponding change of 0.2 in the anthropogenic component of AOT (assuming a unit value of AOT). This uncertainty would then be passed along to any satellite-derived estimates

  19. Fractionation of distillers dried grains with solubles (DDGS) through a narrowing of particle size distribution followed by aspiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distillers dried grains with solubles (DDGS) may have more value and utility if they can be separated into high protein and high fiber fractions. A variety of such separation processes have been proposed; two of the most promising processes involve 3 screening and 3 air classification unit operatio...

  20. Inert gases in a terra sample - Measurements in six grain-size fractions and two single particles from Lunar 20.

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Lakatos, S.; Walton, J. R.

    1973-01-01

    Review of the results of inert gas measurements performed on six grain-size fractions and two single particles from four samples of Luna 20 material. Presented and discussed data include the inert gas contents, element and isotope systematics, radiation ages, and Ar-36/Ar-40 systematics.

  1. Biological activity of ethanolic extract fractions of Dracaena arborea against infestation of stored grains by two storage insect pests.

    PubMed

    Epidi, T T; Udo, I O

    2009-07-01

    As part of on-going efforts to use eco-friendly alternatives to chemical pesticides, ethanolic extract of dried leaves of Dracaena arborea (Willd.) Link (Dragon tree; Dracaenaceae) dissolved in distilled water and partitioned between equal volumes of n-hexane, chloroform, ethyl acetate and butanol was assessed in the laboratory against infestation by Sitophillus zeamais Motsch. and Callosobruchus maculatus Walp. in stored maize and cowpea, respectively. One hundred grams each of maize grains and cowpea seeds were treated with 400 mg kg(-1) of each extract fraction to evaluate contact toxicity, damage assessment, effect on eggs and immature stages and progeny production in both insect species. Contact toxicity by topical application, toxicity upon filter paper application and repellency using area preference method were carried out on the two insect species. Results showed that the extract fraction caused significant (p < or = 0.05) mortality of both insect pests with a high residual contact activity against S. zeamais. Grain damage was significantly (p < or = 0.01) reduced, while progeny production and development of eggs within grains were inhibited. The extract fractions evoked a strong repellent action against S. zeamais but moderate action against C. maculatus. The full potentials of using extract fractions of D. arborea as grain protectant against infestation by insect pests is discussed.

  2. Increasing density leads to generalization in both coarse-grained habitat selection and fine-grained resource selection in a large mammal.

    PubMed

    van Beest, Floris M; Uzal, Antonio; Vander Wal, Eric; Laforge, Michel P; Contasti, Adrienne L; Colville, David; McLoughlin, Philip D

    2014-01-01

    Density is a fundamental driver of many ecological processes including habitat selection. Theory on density-dependent habitat selection predicts that animals should be distributed relative to profitability of habitat, resulting in reduced specialization in selection (i.e. generalization) as density increases and competition intensifies. Despite mounting empirical support for density-dependent habitat selection using isodars to describe coarse-grained (interhabitat) animal movements, we know little of how density affects fine-grained resource selection of animals within habitats [e.g. using resource selection functions (RSFs)]. Using isodars and RSFs, we tested whether density simultaneously modified habitat selection and within-habitat resource selection in a rapidly growing population of feral horses (Equus ferus caballus Linnaeus; Sable Island, Nova Scotia, Canada; 42% increase in population size from 2008 to 2012). Among three heterogeneous habitat zones on Sable Island describing population clusters distributed along a west-east resource gradient (west-central-east), isodars revealed that horses used available habitat in a density-dependent manner. Intercepts and slopes of isodars demonstrated a pattern of habitat selection that first favoured the west, which generalized to include central and east habitats with increasing population size consistent with our understanding of habitat quality on Sable Island. Resource selection functions revealed that horses selected for vegetation associations similarly at two scales of extent (total island and within-habitat zone). When densities were locally low, horses were able to select for sites of the most productive forage (grasslands) relative to those of poorer quality. However, as local carrying capacity was approached, selection for the best of available forage types weakened while selection for lower-quality vegetation increased (and eventually exceeded that of grasslands). Isodars can effectively describe coarse-grained

  3. Autonomous Information Unit for Fine-Grain Data Access Control and Information Protection in a Net-Centric System

    NASA Technical Reports Server (NTRS)

    Chow, Edward T.; Woo, Simon S.; James, Mark; Paloulian, George K.

    2012-01-01

    As communication and networking technologies advance, networks will become highly complex and heterogeneous, interconnecting different network domains. There is a need to provide user authentication and data protection in order to further facilitate critical mission operations, especially in the tactical and mission-critical net-centric networking environment. The Autonomous Information Unit (AIU) technology was designed to provide the fine-grain data access and user control in a net-centric system-testing environment to meet these objectives. The AIU is a fundamental capability designed to enable fine-grain data access and user control in the cross-domain networking environments, where an AIU is composed of the mission data, metadata, and policy. An AIU provides a mechanism to establish trust among deployed AIUs based on recombining shared secrets, authentication and verify users with a username, X.509 certificate, enclave information, and classification level. AIU achieves data protection through (1) splitting data into multiple information pieces using the Shamir's secret sharing algorithm, (2) encrypting each individual information piece using military-grade AES-256 encryption, and (3) randomizing the position of the encrypted data based on the unbiased and memory efficient in-place Fisher-Yates shuffle method. Therefore, it becomes virtually impossible for attackers to compromise data since attackers need to obtain all distributed information as well as the encryption key and the random seeds to properly arrange the data. In addition, since policy can be associated with data in the AIU, different user access and data control strategies can be included. The AIU technology can greatly enhance information assurance and security management in the bandwidth-limited and ad hoc net-centric environments. In addition, AIU technology can be applicable to general complex network domains and applications where distributed user authentication and data protection are

  4. Explanation of Europa's Unusual Polarization Properties: The Regolith is Sub-micron, Fine-Grained, High Porosity Material

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.; Boryta, M. D.; Hapke, B. W.; Manatt, K. S.; Nebedum, A.; Kroner, D. O.; Shkuratov, Y.; Psarev, V.; Vanderoort, K.; Smythe, W. D.

    2015-12-01

    For several decades, unusual reflectance and polarization phase curves have been reported on Europa by experienced ground based astronomers (Rosenbush et al., 1997, 2015). The observed reflectance phase curve is consistent with the phase curves reported in the laboratory in fine grained particulate media (Nelson et al., 2000, 2002, Shkuratov et al., 2002). Shkuratov et al. (2002) also measured polarization properties of fine grained media showing that they relate to the coherent backscatter enhancement phenomenon and are consistent with the astronomical data. We have reconfigured a goniometric photopolarimeter (GPP) (Nelson et al., 2000, 2002) to measure in the laboratory the polarization phase curves of highly reflective particulate materials that simulate the Europa's predominately water ice regolith. We apply the Helmholtz Reciprocity Principle - we present our samples with linearly polarized light and measure the change in the intensity of the reflected component with phase angle from 0.05 to 15 degrees. This is physically equivalent to the astronomical polarization measurements. We report here the polarization phase curves for a suite of high albedo particulates of size 0.1fine grained and with very high porosity, perhaps with void space exceeding 90%. If a reflectance phase curve and a polarization phase curve of solar system object can be obtained (even at a very small range of phase angles), it will soon be possible to determine (or at least constrain) important regolith properties. Future missions to the Jovian

  5. OSL dating as a possible tool for provenance study of fine grained quartz/polymineral from Lake Suigetsu sediments

    NASA Astrophysics Data System (ADS)

    Sugisaki, S.; Murray, A. S.; Buylaert, J.; Tada, R.; Suzuki, Y.; Nagashima, K.; Schwenninger, J.; Haraguchi, T.; Gotanda, K.; Nakagawa, T.

    2013-12-01

    m fraction was extracted from the sediments, and equivalent doses were measured using a double SAR (infrared (IR) and blue light) and post-IR IR (pIRIR 180) respectively. The results show that quartz and polyminerals from type 1 lithology give relatively low and similar equivalent doses throughout each section, whilst quartz and polyminerals in layers of type 2 and 3 give up to 6 times higher equivalent dose than those of adjacent type 1 sediments. We discuss the possible source of quartz in each type of lithology based on fine-grained quartz and polymineral OSL and identify the most suitable lithology for OSL dating for future study.

  6. Low magnification EBSD mapping of texture distribution in a fine-grained matrix

    NASA Astrophysics Data System (ADS)

    Gardner, Joseph; Mariani, Elisabetta; Wheeler, John

    2016-04-01

    The study of texture (CPO) in rocks is often restricted to individual phases within a given sample or specific area of said sample. Large scale EBSD mapping of the matrix of a greenschist facies albite mylonite has shown that an overall significant CPO within albite grains is strongly domainal, and each domain has a unique CPO that is independent of both common slip systems in plagioclase and the specimen geometry (i.e. foliation and lineation). Observational evidence suggests the metamorphic breakdown of plagioclase to albite (Ab) plus a Ca-bearing phase (clinozoisite, Cz) has produced a two phase mixture in which each phase has a contrasting solubility. New grains of albite are thought to nucleate epitaxially from original plagioclase as a reaction front passes through parent grains. A pseudomorphic region of Ab plus Cz after an original plagioclase crystal, protected from intense deformation by enclosure in a cm-scale augite clast, gives insight into pre-deformation daughter grain distributions. The albite in the region inherits a strong CPO and 180° misorientation peak from a relict twin pattern due to epitaxial growth while clinozoisite is randomly distributed and oriented (despite some grains nucleating from the plagioclase parent twin boundary). In the deformed matrix, daughter Ab is seen to be the more mobile phase, having undergone obvious dissolution, transport and reprecipitation into fractures and pressure shadows, whereas Cz grains are relatively insoluble and rotate into parallelism with the foliation, forming bands that anastamose around Cpx porphyroclasts. Despite this modification, albite in the matrix retains significant CPOs that comprise distinct domains with sharp boundaries. A 180° misorientation peak thought to be a signature of twinning inherited from parent plagioclase is also observed in each domain. Why a CPO should be preserved under these conditions (contrary to our traditional understanding that CPOs are a signature of dislocation

  7. Stabilization of Fine-Grained Soil for Road and Airfield Construction.

    DTIC Science & Technology

    1986-07-01

    The admixture of different soil types (i.e., mixing a clay binder with a coarse-grained material). These techniques are usually combined for better...This causes the organic material to remain inactive or less active , %-11- % % -1 00 C _ Cement 80 - 0.5 Sodium Sulphate P1.0 Sodium Sulphate 2.0 Sodium...alkaline condition to be effective. , Eades and Grim (1966) found that, for a pozzolanic reaction to occur, the soil-lime mixture must have a pH of 12.4 one

  8. Determination of fractionation of oxygen isotopes between rice grain and environmental water

    NASA Astrophysics Data System (ADS)

    Kaushal, R.; Ghosh, P.

    2013-12-01

    Oxygen isotopic composition (δ18O) of plant organic matter (POM) serves as a valuable proxy for paleoclimatic studies [1].The δ18O of POM emulates the isotopic composition of the source water [2]. Rice crop cultivation goes back to 12,000 years, when rice was first domesticated in China and the earliest cultivation of rice observed in India was during 3000- 2500 BC. Presently rice is cultivated in many countries around the world including India where the prerequisite of saturated soil water condition for optimum growth of rice crop is provided by the South west monsoons. Earlier studies on δ18O of rice have been limited to its geographic characterization [3]. However, detailed investigations to determine fractionation of oxygen isotopes in water, in different parts of a rice plant, with rice seed organic matter is the primary objective of this work. This is important for understanding the mechanism responsible for the transfer of source water signature to the seed organics and can facilitate understanding of past monsoonal regime using well preserved rice grain remains from archaeological sites. Water from the leaves and culms was extracted by means of heating and cryogenic distillation in a vacuum extraction system [4]. The source water and the water extracted from plant parts were analysed by CO2 equilibration method using Gas Bench peripheral. Rice seed powder, after removal of husk, is composed primarily of starch and were analysed using High Temperature Conversion-Elemental Analyser. Both these peripherals were coupled to an Isotope Ratio Mass spectrometer- MAT253 (Thermo Finnigan). Experimental results discussed here were based on greenhouse and field based studies of water and seed organic composition. The water fed to the plant in the green house showed an average δ18O value of -0.50‰ whereas the field water from irrigation covering the time of grain filling ranges between -1.03‰ and -3.08‰. Figure 1 displays the extent of enrichment recorded in

  9. Microbial colonization and degradation of polyethylene and biodegradable plastic bags in temperate fine-grained organic-rich marine sediments.

    PubMed

    Nauendorf, Alice; Krause, Stefan; Bigalke, Nikolaus K; Gorb, Elena V; Gorb, Stanislav N; Haeckel, Matthias; Wahl, Martin; Treude, Tina

    2016-02-15

    To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material.

  10. Anomalous D-Log E curve with high contrast developer Kodak D8 on ultra fine grain emulsion BB640.

    PubMed

    Ulibarrena, M; Mendez, M; Blaya, S; Fimia, A

    2001-12-03

    D-Log E curves, also known as H-D curves, are used since the XIX century as a tool for describing the characteristics of silver halide emulsions. This curve has a very standard shape, with a linear region, a toe, a shoulder and a solarization region. In this work we present a distortion of the usual curve due to the action of a high contrast developer, Kodak D8, on an ultra fine grain emulsion, BB640\\cite{ov04}. The solarization effect is replaced by a linear zone where developed densities increase with increasing exposures, until all silver halide present in the emulsion is reduced by developer D8 to metallic silver. Densities higher than 11 have been obtained.

  11. Measurement of saturated hydraulic conductivity in fine-grained glacial tills in Iowa: Comparison of in situ and laboratory methods

    USGS Publications Warehouse

    Bruner, D. Roger; Lutenegger, Alan J.

    1994-01-01

    Nested-standpipe and vibrating-wire piezometers were installed in Pre-Illinoian Wolf Creek and Albernett formations at the Eastern Iowa Till Hydrology Site located in Linn County, Iowa. These surficial deposits are composed of fine-grained glacial diamicton (till) with occasional discontinuous lenses of sand and silt. They overlie the Silurian (dolomite) aquifer which provides private, public, and municipal drinking water supplies in the region. The saturated hydraulic conductivity of the Wolf Creek Formation was investigated in a sub-area of the Eastern Iowa Till Hydrology Site. Calculations of saturated hydraulic conductivity were based on laboratoryflexible-wall permeameter tests, bailer tests, and pumping test data. Results show that bulk hydraulic conductivity increases by several orders of magnitude as the tested volume of till increases. Increasing values of saturated hydraulic conductivity at larger spatial scales conceptually support a double-porosity flow model for this till.

  12. Sources of fine-grained sediment in the Linganore Creek watershed, Frederick and Carroll Counties, Maryland, 2008-10

    USGS Publications Warehouse

    Gellis, Allen C.; Noe, Gregory B.; Clune, John W.; Myers, Michael K.; Hupp, Cliff R.; Schenk, Edward R.; Schwarz, Gregory E.

    2015-01-01

    Management implications of this study indicate that both agriculture and streambanks are important sources of sediment in Linganore Creek where the delivery of agriculture sediment was 4 percent and the delivery of streambank sediment was 44 percent. Fourth order streambanks, on average, had the highest rates of bank erosion. Combining the sediment fingerprinting and sediment budget results indicates that 96 percent of the eroded fine-grained sediment from agriculture went into storage. Flood plains and ponds are effective storage sites of sediment in the Linganore Creek watershed. Flood plains stored 8 percent of all eroded sediment with 4th and 5th order flood plains, on average, storing the most sediment. Small ponds in the Linganore Creek watershed, which drained 16 percent of the total watershed area, stored 15 percent of all eroded sediment. Channel beds were relatively stable with the greatest erosion generally occurring in 4th and 5th order streams.

  13. Thermal shock behavior of fine grained W-Y2O3 materials fabricated via two different manufacturing technologies

    NASA Astrophysics Data System (ADS)

    Zhao, Mingyue; Zhou, Zhangjian; Zhong, Ming; Tan, Jun; Lian, Youyun; Liu, Xiang

    2016-03-01

    Thermal shock resistance of fine grained W-Y2O3 materials fabricated by two different manufacturing technologies (i.e. spark plasma sintering and high temperature sintering in combination with hot rolling deformation) was examined under transient high heat loads below and slightly above the melting threshold of pure tungsten. The tests were performed with the electron beam test facility EMS-60 at Southwestern Institute of Physics, China. The comparison of the thermal shock response in this work showed that the deformed W-Y2O3 performed a superior behavior to spark plasma sintered W-Y2O3 in suppressing the crack formation, melting resistance and recrystallization resistance. The thermo-physical properties and mechanical characterizations necessary for understanding the thermal shock response of these materials were also presented and discussed.

  14. Large, high-intensity fire events in Southern California shrublands: Debunking the fine-grain age patch model

    USGS Publications Warehouse

    Keeley, J.E.; Zedler, P.H.

    2009-01-01

    We evaluate the fine-grain age patch model of fire regimes in southern California shrublands. Proponents contend that the historical condition was characterized by frequent small to moderate size, slow-moving smoldering fires, and that this regime has been disrupted by fire suppression activities that have caused unnatural fuel accumulation and anomalously large and catastrophic wildfires. A review of more than 100 19th-century newspaper reports reveals that large, high-intensity wildfires predate modern fire suppression policy, and extensive newspaper coverage plus first-hand accounts support the conclusion that the 1889 Santiago Canyon Fire was the largest fire in California history. Proponents of the fine-grain age patch model contend that even the very earliest 20th-century fires were the result of fire suppression disrupting natural fuel structure. We tested that hypothesis and found that, within the fire perimeters of two of the largest early fire events in 1919 and 1932, prior fire suppression activities were insufficient to have altered the natural fuel structure. Over the last 130 years there has been no significant change in the incidence of large fires greater than 10000 ha, consistent with the conclusion that fire suppression activities are not the cause of these fire events. Eight megafires (???50 000 ha) are recorded for the region, and half have occurred in the last five years. These burned through a mosaic of age classes, which raises doubts that accumulation of old age classes explains these events. Extreme drought is a plausible explanation for this recent rash of such events, and it is hypothesized that these are due to droughts that led to increased dead fine fuels that promoted the incidence of firebrands and spot fires. A major shortcoming of the fine-grain age patch model is that it requires age-dependent flammability of shrubland fuels, but seral stage chaparral is dominated by short-lived species that create a dense surface layer of fine

  15. Large, high-intensity fire events in southern California shrublands: debunking the fine-grain age patch model.

    PubMed

    Keeley, Jon E; Zedler, Paul H

    2009-01-01

    We evaluate the fine-grain age patch model of fire regimes in southern California shrublands. Proponents contend that the historical condition was characterized by frequent small to moderate size, slow-moving smoldering fires, and that this regime has been disrupted by fire suppression activities that have caused unnatural fuel accumulation and anomalously large and catastrophic wildfires. A review of more than 100 19th-century newspaper reports reveals that large, high-intensity wildfires predate modern fire suppression policy, and extensive newspaper coverage plus first-hand accounts support the conclusion that the 1889 Santiago Canyon Fire was the largest fire in California history. Proponents of the fine-grain age patch model contend that even the very earliest 20th-century fires were the result of fire suppression disrupting natural fuel structure. We tested that hypothesis and found that, within the fire perimeters of two of the largest early fire events in 1919 and 1932, prior fire suppression activities were insufficient to have altered the natural fuel structure. Over the last 130 years there has been no significant change in the incidence of large fires greater than 10,000 ha, consistent with the conclusion that fire suppression activities are not the cause of these fire events. Eight megafires (> or = 50,000 ha) are recorded for the region, and half have occurred in the last five years. These burned through a mosaic of age classes, which raises doubts that accumulation of old age classes explains these events. Extreme drought is a plausible explanation for this recent rash of such events, and it is hypothesized that these are due to droughts that led to increased dead fine fuels that promoted the incidence of firebrands and spot fires. A major shortcoming of the fine-grain age patch model is that it requires age-dependent flammability of shrubland fuels, but seral stage chaparral is dominated by short-lived species that create a dense surface layer of

  16. Distribution, thickness, and volume of fine-grained sediment from precipitation of metals from acid-mine waters in Keswick Reservoir, Shasta County, California

    USGS Publications Warehouse

    Bruns, Terry R.; Alpers, Charles N.; Carlson, Paul

    2006-01-01

    In February 1993, the U.S. Geological Survey (USGS) acquired high-resolution seismic-reflection data to map the distribution and thickness of fine-grained sediments associated with acid-mine drainage in Keswick Reservoir on the Sacramento River, near Redding, California. In the Spring Creek Arm of Keswick Reservoir, the sediments occurred in three distinct accumulations; thicknesses are greater than 2 meters (m) in the western accumulation, greater than 5 m in the central accumulation, and up to 8 m in the eastern accumulation. In Keswick Reservoir, fine-grained sediments related to acid-mine drainage were present from slightly north of the Spring Creek Arm downstream to the Keswick Dam. Sediment thickness varies from about 3 m opposite the mouth of the Spring Creek Arm to less than 1 m near Keswick Dam. Our estimate for the total volume of fine-grained sediments in the Spring Creek Arm at the time of the geophysical survey in February 1993 is about 152,000 cubic meters in three sediment accumulations, with about 14,000, 32,000, and 105,000 cubic meters respectively in the western, central, and eastern accumulations. We interpreted that an additional 110, 000 cubic meters of material was present in the main part of Keswick Reservoir. At the time of data collection, we therefore estimate that the total volume of fine-grained sediment was 260,000 cubic meters. In the main part of Keswick Reservoir, 42% to 50% of the reservoir area contiguous to Spring Creek Arm had mappable fine-grained sediments. Decreasing sediment supply down-reservoir meant that mappable sediment covered only about 35% of the reservoir in the area to the south, decreasing to about 12% near Keswick Dam. Much of the reservoir bottom below the Spring Creek Arm could have had a thin (less than 20-30 cm) cover of fine-grained sediment that was not mappable using the seismic-reflection data.

  17. Free Enthalpy Differences between α-, π-, and 310-Helices of an Atomic Level Fine-Grained Alanine Deca-Peptide Solvated in Supramolecular Coarse-Grained Water.

    PubMed

    Lin, Zhixiong; Riniker, Sereina; van Gunsteren, Wilfred F

    2013-03-12

    Atomistic molecular dynamics simulations of peptides or proteins in aqueous solution are still limited to the multi-nanosecond time scale and multi-nanometer range by computational cost. Combining atomic solutes with a supramolecular solvent model in hybrid fine-grained/coarse-grained (FG/CG) simulations allows atomic detail in the region of interest while being computationally more efficient. We used enveloping distribution sampling (EDS) to calculate the free enthalpy differences between different helical conformations, i.e., α-, π-, and 310-helices, of an atomic level FG alanine deca-peptide solvated in a supramolecular CG water solvent. The free enthalpy differences obtained show that by replacing the FG solvent by the CG solvent, the π-helix is destabilized with respect to the α-helix by about 2.5 kJ mol(-1), and the 310-helix is stabilized with respect to the α-helix by about 9 kJ mol(-1). In addition, the dynamics of the peptide becomes faster. By introducing a FG water layer of 0.8 nm around the peptide, both thermodynamic and dynamic properties are recovered, while the hybrid FG/CG simulations are still four times more efficient than the atomistic simulations, even when the cutoff radius for the nonbonded interactions is increased from 1.4 to 2.0 nm. Hence, the hybrid FG/CG model, which yields an appropriate balance between reduced accuracy and enhanced computational speed, is very suitable for molecular dynamics simulation investigations of biomolecules.

  18. Erosion of fine-grained sediment in the Hudson Shelf Valley, offshore of New York

    NASA Astrophysics Data System (ADS)

    Traykovski, P.; Harris, C. K.; Butman, B.; ten Brink, M. R.

    2001-05-01

    The Hudson Shelf Valley, the submerged ancestral drainage channel of the Hudson River, is a major topographic feature on the continental shelf of the New York Bight. The area near the head of the valley has been used for disposal of a wide variety of material, including dredged material (since the late 1800's) and sewage sludge (between 1972 and 1987). While the shelf is covered by primarily sandy sediments, finer sediments are found in the valley; these fine sediments have elevated concentrations of heavy metals and other contaminants. In order to understand the fate of these contaminated sediments in the winter of 1999-2000 an array of six tripods (four along the valley axis and 2 on the adjacent shelf) was deployed in the Valley and in the New York Bight to measure the regional pattern of sediment transport. At two sites (one at the head of the valley and one in the axis of the upper valley) where the surficial sediments are silty sand or sandy silt, erosion of up to 15 cm of sediment was observed under the tripods using an acoustic altimeter. The erosion took place over the first two months of the deployment in steps of 1 to 3 cm during 2 to 5 day periods of high wave energy and/or strong mean currents. The critical stress for resuspension/erosion increased as the bed eroded, thus ultimately limiting the amount of erosion. Since this large erosion rate is unlikely to be sustainable over large areas and over longer time scales, the observed erosion suggests that there may be mobile pools of fine sediment over more consolidated sediments that are easily erodable and transported during high energy events.

  19. Thin-sectioning and analysis of fine-grained meteoritic materials

    NASA Astrophysics Data System (ADS)

    Brooks, Donald A.; Bradley, John P.

    1992-06-01

    The overall theme of the work was the identification of the sources and formation/aggregation mechanisms of the various classes of interplanetary dust particles (IDP's) and to clarify the relationship between IDP's and conventional meteorites. IDP's are believed to be derived from a much broader range of parent bodies than conventional meteorites. Some of these parent bodies (e.g., comets) have escaped that post accretional processing that has affected the parent bodies of meteorites. Therefore, IDP's are likely to preserve a record of early solar system and possibly presolar grain forming reactions. Using analytical electron microscopy (AEM) and more recently micro-infrared (IR) microspectroscopy to examine ultramicrotomed thin sections, we have addressed the questions of IDP formation mechanisms, sources, and their relationship to conventional meteorites. The following sections describe specific findings resulting from these studies.

  20. Thin-sectioning and analysis of fine-grained meteoritic materials

    NASA Technical Reports Server (NTRS)

    Brooks, Donald A. (Editor); Bradley, John P.

    1992-01-01

    The overall theme of the work was the identification of the sources and formation/aggregation mechanisms of the various classes of interplanetary dust particles (IDP's) and to clarify the relationship between IDP's and conventional meteorites. IDP's are believed to be derived from a much broader range of parent bodies than conventional meteorites. Some of these parent bodies (e.g., comets) have escaped that post accretional processing that has affected the parent bodies of meteorites. Therefore, IDP's are likely to preserve a record of early solar system and possibly presolar grain forming reactions. Using analytical electron microscopy (AEM) and more recently micro-infrared (IR) microspectroscopy to examine ultramicrotomed thin sections, we have addressed the questions of IDP formation mechanisms, sources, and their relationship to conventional meteorites. The following sections describe specific findings resulting from these studies.

  1. Surface modifications on toughened, fine-grained, recrystallized tungsten with repetitive ELM-like pulsed plasma irradiation

    NASA Astrophysics Data System (ADS)

    Kikuchi, Y.; Sakuma, I.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M.; Ueda, Y.; Kurishita, H.

    2015-08-01

    Surface modifications of toughened, fine-grained, recrystallized tungsten (TFGR W) materials with 1.1 wt.% TiC and 3.3 wt.% TaC dispersoids due to repetitive ELM-like pulsed (∼0.15 ms) helium plasma irradiation have been investigated by using a magnetized coaxial plasma gun. No surface cracking at the center part of the TFGR W samples exposed to 20 plasma pulses of ∼0.3 MJ m-2 was observed. The suppression of surface crack formation due to the increase of the grain boundary strength by addition of TiC and TaC dispersoids was confirmed in comparison with a pure W material. On the other hand, surface cracks and small pits appeared at the edge part of the TFGR W sample after the pulsed plasma irradiation. Erosion of the TiC and TaC dispersoids due to the pulsed plasma irradiation could cause the small pits on the surface, resulting in the surface crack formation.

  2. Step heating of 40Ar/ 39Ar standard mineral mixtures: Investigation of a fine-grained bulk sediment provenance tool

    NASA Astrophysics Data System (ADS)

    VanLaningham, Sam; Mark, Darren F.

    2011-05-01

    Quantitative techniques that link sediments to their sources are needed to understand a range of tectonic, climate, and anthropogenic driven Earth surface processes. Many provenance techniques exist for sand-sized material but fewer are available for fine-grained sediment archives. In this respect, bulk 40Ar/ 39Ar ages from silt-sized sediment show potential, but many questions remain about the significance of a bulk sediment 40Ar/ 39Ar age. We interrogate bulk sediment 40Ar/ 39Ar ages by step heating mixtures of well-constrained 40Ar/ 39Ar mineral standards crushed to silt-sized. Silt-sized end member components Alder Creek Sanidine, Taylor Creek Sanidine and Heidelberg Biotite all yield plateau ages within uncertainty of their coarse-grained counterparts. High-resolution step heating (as many as 43 steps) of the mineral mixtures shows that biotite degasses first at lower temperatures compared to the two sanidines that degas generally in concert. Concordant age steps develop at both low and high temperatures and the transition from the isotope signal being dominated by one mineral phase to another is clearly observed. We show that age spectra for the mineral standard mixtures can be modeled and predicted for all mixtures by assuming a (simplistic) Gaussian distributed release of Ar, and by using the degassing maxima, variance, K concentration, and 40Ar/ 39Ar age of each monitor mineral. Thus, bulk sediment 40Ar/ 39Ar ages can be robust indicators of the average cooling/crystallization age of all contributing K-bearing minerals to a depositional center. Furthermore, we discuss the potential to deconvolve individual mineral age populations by model inversion. The application of this bulk sediment provenance technique should not be considered a replacement for single grain analyses. It should be applied to environments that do not provide sand-sized sediment archives (e.g., distal terrigenous sedimentary archives) when information about source changes through time

  3. The Ar-Nd Isotopic Fingerprinting Technique: Provenance Applications to Fine-Grained Fluvial and Marine Sediment

    NASA Astrophysics Data System (ADS)

    Vanlaningham, S.; Duncan, R. A.; Pisias, N. G.; Graham, D. W.

    2006-12-01

    Establishing new techniques that can trace terrigenous sediment to its continental source remains an important area of study for understanding Earth's climatic and tectonic history. Marine sedimentary sequences capture particularly complete records of oceanic and terrestrial processes, yet the fine-grained nature of material deposited in the ocean hinders the usage of single-grain provenance techniques. We show initial results of a new Ar-Nd "fingerprinting" method applied to bulk fine-grained river sediments from the Pacific Northwest and bulk terrigenous sediments from core EW9504-17PC, offshore the California-Oregon margin. We resolve likely sediment sources to the core site into four major domains in bulk sediment ^{40}Ar- 39Ar ages and Nd isotopic compositions (ɛNd ). North of the core site, the fluvial material from the Umpqua River has a ^{40}Ar-39Ar bulk sediment age of 92±7 Ma while ɛNd = -5±1. Along the same latitude of the core site, the Rogue River has a ^{40}Ar-39Ar bulk sediment age of 129±3 Ma while ɛNd = -1±1. The Klamath River, which drains similar lithologies to the Rogue River, shows a somewhat distinct Ar-Nd fingerprint (^{40}Ar-39Ar = 151±4 Ma, ɛNd = 0±1). The Eel River, to the south of the core site, has a similar bulk sediment age to the Rogue River (^{40}Ar-39Ar = 128±5 Ma) but a different ɛNd of -3±1. The contrast in these Ar-Nd fingerprints allows us to examine whether sediment provenance has changed at the core site on glacial-interglacial timescales. Preliminary downcore ^{40}Ar-39Ar bulk sediment analyses suggest a change in provenance from a source presently dominated by the Eel River, to a source during the Last Glacial Maximum (LGM) that is characterized by younger bulk sediment ages. Downcore ɛNd helps resolve whether this change is due to a shift in ocean circulation (and sediment transport pathways) or spatial patterns of continental weathering and erosion within the Umpqua, Rogue and Klamath Rivers (e.g., the

  4. Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report

    SciTech Connect

    Roy Crooks, Ph.D., P.E.

    2009-10-31

    The positron and electron linacs of the International Linear Collider (ILC) will require over 14,000, nine-cell, one meter length, superconducting radio frequency (SRF) cavities [ILC Reference Design Report, 2007]. Manufacturing on this scale will benefit from more efficient fabrication methods. The current methods of fabricating SRF cavities involve deep drawing of the halves of each of the elliptical cells and joining them by high-vacuum, electron beam welding, with at least 19 circumferential welds per cavity. The welding is costly and has undesirable effects on the cavity surfaces, including grain-scale surface roughening at the weld seams. Hydroforming of seamless tubes avoids welding, but hydroforming of coarse-grained seamless tubes results in strain-induced surface roughening. Surface roughness limits accelerating fields, because asperities prematurely exceed the critical magnetic field and become normal conducting. This project explored the technical and economic feasibility of an improved processing method for seamless tubes for hydroforming. Severe deformation of bulk material was first used to produce a fine structure, followed by extrusion and flow-forming methods of tube making. Extrusion of the randomly oriented, fine-grained bulk material proceeded under largely steady-state conditions, and resulted in a uniform structure, which was found to be finer and more crystallographically random than standard (high purity) RRR niobium sheet metal. A 165 mm diameter billet of RRR grade niobium was processed into five, 150 mm I.D. tubes, each over 1.8 m in length, to meet the dimensions used by the DESY ILC hydroforming machine. Mechanical properties met specifications. Costs of prototype tube production were approximately twice the price of RRR niobium sheet, and are expected to be comparable with economies of scale. Hydroforming and superconducting testing will be pursued in subsequent collaborations with DESY and Fermilab. SRF Cavities are used to construct

  5. Fine-grained Goethite as a Precursor for Martian Gray Hematite

    NASA Technical Reports Server (NTRS)

    Glotch, T. D.; Morris, R. V.; Sharp, T. G.; Christensen, P. R.

    2003-01-01

    Several isolated deposits of gray, crystalline hematite on Mars were discovered using data returned from the Thermal Emission Spectrometer (TES) instrument aboard the Mars Global Surveyor spacecraft. Christensen et al. provided five testable hypotheses regarding the formation of crystalline hematite on Mars: 1) low-temperature precipitation of Fe oxides/hydroxides from standing, oxygenated, Fe-rich water, followed by subsequent alteration to gray hematite, 2) low-temperature leaching of iron-bearing silicates and other materials leaving a Fe-rich residue laterite-style weathering) which is subsequently altered to gray hematite, 3) direct precipitation of gray hematite from Fe-rich circulating fluids of hydrothermal or other origin, 4) formation of gray hematitic surface coatings during weathering, and 5) thermal oxidation of magnetite-rich lavas. Since this initial work, several authors have examined the hematite deposits to determine their formation mechanism. Lane et al. cited the absence of a 390/ cm absorption in the martian hematite spectrum as evidence for platy hematite grains. Their model for the formation of the deposits includes deposition of any of a variety of iron oxides or oxyhydroxides by aqueous or hydrothermal fluids, burial and metamorphosis to gray platy hematite grains, and exhumation in recent times. Based on a detailed geomorphic examination of the Sinus Meridiani region, Hynek et al. conclude that the most likely method of hematite formation was either emplacement by a hydrothermal fluid or oxidation of a magnetite-rich pyroclastic deposit. Similarly, Arvidson et al., favor a model involving the alteration of pyroclastic deposits by aqueous or hydrothermal fluids. Finally, based on geochemical modeling and an examination of Aram Chaos, Catling and Moore favor emplacement by hydrothermal fluids with a minimum temperature of 100 C. Comparison of the average martian hematite spectrum measured by TES to hematite emissivity spectra for a variety

  6. Measurement of Fine-Grained Aspects of Toddler Temperament: The Early Childhood Behavior Questionnaire

    PubMed Central

    Putnam, Samuel P.; Gartstein, Maria A.; Rothbart, Mary K.

    2015-01-01

    This article describes the development, reliability, and factor structure of a finely differentiated (18 dimensions) parent-report measure of temperament in 1.5 to 3-year-old children, using a cross-sectional sample (N = 317) and a longitudinal sample of primary (N = 104) and secondary (N = 61) caregivers. Adequate internal consistency was demonstrated for all scales and moderate inter-rater reliability was evident for most scales. Longitudinal stability correlations were primarily large over 6- and 12-month spans and moderate to large from 18 to 36 months. Factor analysis revealed a three-factor structure of Surgency/Extraversion, Negative Affectivity, and Effortful Control. In both samples and for both primary and secondary caregivers, older children received higher scores for Attention Focusing, Discomfort, Inhibitory Control, and Positive Anticipation. Primary caregivers rated females higher in Fear, and lower in High-intensity Pleasure, than males; secondary caregivers rated females higher than males in several aspects of Effortful Control. PMID:17138293

  7. Analytical electron microscopy of fine-grained phases in primitive interplanetary dust particles and carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    MacKinnon, Ian D. R.; Rietmeijer, Frans J. M.; McKay, David S.

    1987-05-01

    In order to describe the total mineralogical diversity within primitive extraterrestrial materials, individual interplanetary dust particles (IDPs) collected from the stratosphere as part of the JSC Cosmic Dust Curatorial Program were analyzed using a variety of AEM techniques. Identification of over 250 individual grains within one chondritic porous (CP) IDP shows that most phases could be formed by low temperature processes and that heating of the IDP during atmospheric entry is minimal and less than 600 C. In a review of the mineralogy of IDPs, it was suggested that the occurrence of other silicates such as enstatite whiskers is consistent with the formation in an early turbulent period of the solar nebula. Experimental confirmation of fundamental chemical and physical processes in a stellar environment, such as vapor phase condensation, nucleation, and growth by annealing, is an important aspect of astrophysical models for the evolution of the Solar System. A detailed comparison of chondritic IDP and carbonaceous chondrite mineralogies shows significant differences between the types of silicate minerals as well as the predominant oxides.

  8. Preparation of thin, fine-grained, tantalum metal replicas for freeze-fracture electron microscopy.

    PubMed

    Costello, M J; Escaig, J

    1989-01-01

    Two critical factors in the preparation of metal films on biological specimens are the type of metal used and the potentially damaging effects of radiant energy from the hot metal source. The excessive heating of surfaces is a major limitation to the replication of heat-sensitive aqueous specimens with refractory metals such as tungsten and tantalum, although these metals are known to form smaller grains and thinner films than the more commonly used platinum/carbon deposited under similar conditions. We describe here an electron gun designed for the evaporation of pure tantalum; surface heating is reduced through intermittent deposition controlled by varying the open/closed intervals of a fast shutter that operates in ultra-high vacuum. The effectiveness of the shutter was evaluated with a thin thermocouple in place of the specimen. The composition of the replicas was determined by x-ray microanalysis and by direct observation of the initial melting and subsequent evaporation of the tantalum bead supported on a tungsten rod that remained unchanged during the evaporation. The quality of the tantalum replicas was demonstrated with freeze-fracture replicas of reconstituted proteoliposomes and native membrane vesicles. With shutter intervals of 0.5 sec open and 1.0 sec closed, the surface heating was reduced enough to prevent unintentional etching and to preserve small pits complementary to protein particles in hydrophobic membrane surfaces and in ice.

  9. Analytical electron microscopy of fine-grained phases in primitive interplanetary dust particles and carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Mackinnon, Ian D. R.; Rietmeijer, Frans J. M.; Mckay, David S.

    1987-01-01

    In order to describe the total mineralogical diversity within primitive extraterrestrial materials, individual interplanetary dust particles (IDPs) collected from the stratosphere as part of the JSC Cosmic Dust Curatorial Program were analyzed using a variety of AEM techniques. Identification of over 250 individual grains within one chondritic porous (CP) IDP shows that most phases could be formed by low temperature processes and that heating of the IDP during atmospheric entry is minimal and less than 600 C. In a review of the mineralogy of IDPs, it was suggested that the occurrence of other silicates such as enstatite whiskers is consistent with the formation in an early turbulent period of the solar nebula. Experimental confirmation of fundamental chemical and physical processes in a stellar environment, such as vapor phase condensation, nucleation, and growth by annealing, is an important aspect of astrophysical models for the evolution of the Solar System. A detailed comparison of chondritic IDP and carbonaceous chondrite mineralogies shows significant differences between the types of silicate minerals as well as the predominant oxides.

  10. Fine coal fractionation using a magnetohydrostatic separation process CRADA 91-003. Final report

    SciTech Connect

    Cho, Heechan; Killmeyer, R. P.

    1992-10-31

    The magnetohydrostatic separation (MHS) process uses a magnetic fluid which has the ability to float a submerged particle in a magnetic field. The objective of this project was to develop a technique for laboratory gravity fractionation of coal using MHS.

  11. On the microstructural and magnetic properties of fine-grained CoFe2O4 ceramics produced by combining polyol process and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Gaudisson, T.; Artus, M.; Acevedo, U.; Herbst, F.; Nowak, S.; Valenzuela, R.; Ammar, S.

    2014-12-01

    Starting from polyol-made CoFe2O4 ferrite nanoparticles of different aggregation states, high-density fine-grained ceramics were produced using Spark Plasma Sintering technique at 600 and 500 °C, under vacuum and applying a uniaxial pressure of more than 80 MPa. The grain growth of thus produced ceramics appears to be proportional to the temperature plateau and inversely proportional to the aggregation state of the initial powders. Average grain sizes ranging between about 50 and 350 nm were obtained. In all the cases, magnetic measurements evidenced a ferrimagnetic behavior at room temperature with non-zero coercivity, while their starting powders exhibited superparamagnetic features.

  12. Investigation of biological activity of fine fraction of lunar surface material returned to earth by the Luna 16 automatic station

    NASA Technical Reports Server (NTRS)

    Kustov, V. V.; Ostapenko, O. F.; Petrukhin, V. G.

    1974-01-01

    The biological action of a sample of lunar surface material returned to earth by the Luna 16 automatic station from a new region of the mare surface on male white mice was studied. The condition and behavior of the animals were observed; the intensity of their oxygen consumption was recorded, and motor activity of the muscles, leucocyte and erythrocytes counts in the peripheral blood, and the activity of whole blood chloinesterase were determined. Experimental results showed that the tested doses of the fine fraction of the lunar surface material from the Sea of Fertility were virtually innocuous for white mice.

  13. A heat treatment procedure to produce fine-grained lamellar microstructures in a P/M titanium aluminide alloy

    NASA Astrophysics Data System (ADS)

    Au, Peter

    A process for fabricating advanced aerospace titanium aluminide alloys starting from metal powders (the hot isostatically consolidated P/M process) is presented in this thesis. This process does not suffer the difficulties of chemical inhomogeneities and coarse grain structure of castings. In addition heat treatments which take advantage of the refined structure of HIP processed materials are developed to achieve microstructure control and subsequent mechanical property control. It is shown that a better "property balance" is possible after the heat treatment of HIP consolidated materials than it is with alternative processing. It is well understood that the standard microstructures (near-gamma, duplex, nearly lamellar, and fully lamellar) do not have the balanced mechanical properties (tensile, yield, creep and fatigue strength, ductility and fracture toughness) necessary for optimal performance in aero engine and automotive applications. In this work a fine-grained fully lamellar (FGFL) microstructure is developed for property control and in particular for achieving a much improved property balance. A heat treatment procedure for this purpose which consists of cyclic processing in the alpha transus temperature region to achieve an FGFL structure with grain sizes in the range of 50 mum to 150 mum is presented. Compared with conventional duplex structured materials, the minimum creep rate is an order of magnitude lower with only a 10% loss in tensile yield strength. Moreover, a three-fold increase in tensile elongation is possible by converting to an FGFL structure with only a 30% loss in minimum creep rate. These are attractive trade-offs when considering the use of these alloys for aerospace purposes. A thorough literature review of the mechanisms of formation of standard microstructures and their deformation under mechanical loading is contained in the thesis. In addition, conventional techniques to produce FGFL microstructures in wrought and cast materials are

  14. Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP)

    SciTech Connect

    Stráská, Jitka; Janeček, Miloš; Čížek, Jakub; Stráský, Josef; Hadzima, Branislav

    2014-08-15

    Thermal stability of the ultra-fine grained (UFG) microstructure of magnesium AZ31 alloy was investigated. UFG microstructure was achieved by a combined two-step severe plastic deformation process: the extrusion (EX) and subsequent equal-channel angular pressing (ECAP). This combined process leads to refined microstructure and enhanced microhardness. Specimens with UFG microstructure were annealed isochronally at temperatures 150–500 °C for 1 h. The evolution of microstructure, mechanical properties and dislocation density was studied by electron backscatter diffraction (EBSD), microhardness measurements and positron annihilation spectroscopy (PAS). The coarsening of the fine-grained structure at higher temperatures was accompanied by a gradual decrease of the microhardness and decrease of dislocation density. Mechanism of grain growth was studied by general equation for grain growth and Arrhenius equation. Activation energies for grain growth were calculated to be 115, 33 and 164 kJ/mol in temperature ranges of 170–210 °C, 210–400 °C and 400–500 °C (443–483 K, 483–673 K and 673–773 K), respectively. - Highlights: • Microhardness of UFG AZ31 alloy decreases with increasing annealing temperature. • This fact has two reasons: dislocation annihilations and/or grain growth. • The activation energies for grain growth were calculated for all temperature ranges.

  15. Cryogenic fractionator gas as stripping gas of fines slurry in a coking and gasification process

    DOEpatents

    DeGeorge, Charles W.

    1981-01-01

    In an integrated coking and gasification process wherein a stream of fluidized solids is passed from a fluidized bed coking zone to a second fluidized bed and wherein entrained solid fines are recovered by a scrubbing process and wherein the resulting solids-liquid slurry is stripped with a stripping gas to remove acidic gases, at least a portion of the stripping gas comprises a gas comprising hydrogen, nitrogen and methane separated from the coker products.

  16. Determination of the effects of fine-grained sediment and other limiting variables on trout habitat for selected streams in Wisconsin

    USGS Publications Warehouse

    Scudder, Barbara C.; Selbig, J.W.; Waschbusch, R.J.

    2000-01-01

    Two Habitat Suitability Index (HSI) models, developed by the U.S. Fish and Wildlife Service, were used to evaluate the effects of fine-grained (less than 2 millimeters) sediment on brook trout (Salvelinusfontinalis, Mitchill) and brown trout (Salmo trutta, Linnaeus) in 11 streams in west-central and southwestern Wisconsin. Our results indicated that fine-grained sediment limited brook trout habitat in 8 of 11 streams and brown trout habitat in only one stream. Lack of winter and escape cover for fry was the primary limiting variable for brown trout at 61 percent of the sites, and this factor also limited brook trout at several stations. Pool area or quality, in stream cover, streambank vegetation for erosion control, minimum flow, thalweg depth maximum, water temperature, spawning substrate, riffle dominant substrate, and dissolved oxygen also were limiting to trout in the study streams. Brook trout appeared to be more sensitive to the effects of fine-grained sediment than brown trout. The models for brook trout and brown trout appeared to be useful and objective screening tools for identifying variables limiting trout habitat in these streams. The models predicted that reduction in the amount of fine-grained sediment would improve brook trout habitat. These models may be valuable for establishing instream sediment-reduction goals; however, the decrease in sediment delivery needed to meet these goals cannot be estimated without quantitative data on land use practices and their effects on sediment delivery and retention by streams.

  17. A Comprehensive Study of Pristine, Fine-grained, Spinel-rich Inclusions from the Leoville and Efremovka CV3 Chondrites. 1; Petrology

    NASA Technical Reports Server (NTRS)

    MacPherson, G. J.; Krot, A. N.; Ulyanov, A. A.; Hicks, T.

    2002-01-01

    Fine-grained spinel-rich CAI from Efremovka and Leoville lack the overprint of Na and Fe metasomatism seen in Allende. They contain spinel, pyroxene, anorthite, and melilite; most have a zoned structure with spinel-rich cores, melilite-rich mantles. Additional information is contained in the original extended abstract.

  18. Fine-Grained Distribution of a Non-Native Resource Can Alter the Population Dynamics of a Native Consumer

    PubMed Central

    2015-01-01

    New interactions with non-native species can alter selection pressures on native species. Here, we examined the effect of the spatial distribution of a non-native species, a factor that determines ecological and evolutionary outcomes but that is poorly understood, particularly on a fine scale. Specifically, we explored a native butterfly population and a non-native plant on which the butterfly oviposits despite the plant’s toxicity to larvae. We developed an individual-based model to describe movement and oviposition behaviors of each butterfly, which were determined by plant distribution and the butterfly's host preference genotype. We estimated the parameter values of the model from rich field data. We simulated various patterns of plant distributions and compared the rates of butterfly population growth and changes in the allele frequency of oviposition preference. Neither the number nor mean area of patches of non-native species affected the butterfly population, whereas plant abundance, patch shape, and distance to the nearest native and non-native patches altered both the population dynamics and genetics. Furthermore, we found a dramatic decrease in population growth rates when we reduced the distance to the nearest native patch from 147 m to 136 m. Thus changes in the non-native resource distribution that are critical to the fate of the native herbivore could only be detected at a fine-grained scale that matched the scale of a female butterfly’s movement. In addition, we found that the native butterfly population was unlikely to be rescued by the exclusion of the allele for acceptance of the non-native plant as a host. This study thus highlights the importance of including both ecological and evolutionary dynamics in analyses of the outcome of species interactions and provides insights into habitat management for non-native species. PMID:26575843

  19. Fluid movement and diagenesis in fine-grained geopressured sediments of Frio Formation (Oligocene), Kaplan field, southwestern Louisiana

    SciTech Connect

    Davis, B.A.; Ferrell, R.E.

    1983-03-01

    Investigation of structure, temperature, pressure, salinity, and core samples at Kaplan field yields information on diagenesis of fine-grained sandstones deposited in an outer shelf/upper slope depositional environment The shallow occurrence of geopressure is related to structure and a high shale/sand ratio. Low isothermal surfaces in the down fault blocks accompanied by anomalous high temperatures in the upthrown blocks indicate vertical leakage of fluids along growth faults from underlying geopressured aquifers. The Frio Formation core samples from 16,700 to 19,600 ft (5090 to 5974 m) of depth, representing channel and channel-edge turbidite sandstones, were examined petrographically and by SEM. The arkosic composition of late stage diagenesis sandstones at Kaplan field suggests an original arkose or lithic arkose composition (classification of McBride). Nonferroan calcite cementation, chlorite rims and cement, and quartz overgrowths characterize early diagenesis. At a middle stage of diagenesis secondary porosity is developed by dissolution of unstable grains and calcite cement. Samples flushed by geopressured waters from greater depth show kaolinite pore-fill and quartz over-growths, chlorite (polytype IIb) and illite cement, and feldspar overgrowths in the late diagenetic stage. The low permeability of sandstones with extensive early chlorite cement (channel-edge sandstones) precludes development of extensive secondary porosity. In contrast, sandstones with little early chlorite cement develop and maintain secondary porosity through the late diagenetic stage. Restriction of fluid movement by early chlorite cement has ramifications for migration of hydrocarbons or geothermal waters, and for gas production at Kaplan field.

  20. Micro-Raman spectroscopic study of fine-grained, shock-metamorphosed rock fragments from the Australasian microtektite layer

    NASA Astrophysics Data System (ADS)

    Glass, B. P.; Fries, M.

    2008-11-01

    Shock-metamorphosed rock fragments have been found in the Australasian microtektite layer from the South China Sea. Previous X-ray diffraction (XRD) studies indicate that the most abundant crystalline phases in the rock fragments are coesite, quartz, and a 10 Å phase (mica/clay?). In addition, the presence of numerous other phases was suggested by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. In the present research, ten of the rock fragments, which had previously been studied using SEM/EDX, were studied by micro-Raman spectroscopy. The presence of K-feldspar, plagioclase, rutile, ilmenite, titanite, magnetite, calcite, and dolomite were confirmed. In addition, the high-pressure TiO2 polymorph with an α-PbO2 structure (i.e., TiO2II) was found in several rock fragments. Two grains previously thought to have been zircon, based on their compositions, were found to have Raman spectra that do not match the Raman spectra of zircon, reidite, or any of the possible decomposition products of zircon or their high-pressure polymorphs. We speculate that the ZrSiO4 phase might be a previously unknown high-pressure polymorph of zircon or one of its decomposition products (i.e., ZrO2 or SiO2). The presence of coesite and TiO2 II, and partial melting and vesiculation suggest that the rock fragments containing the unknown ZrSiO4 phase must have experienced shock pressures between 45 and 60 GPa. We conclude that micro-Raman spectroscopy, in combination with XRD and SEM/EDX, is a powerful tool for the study of small, fine-grained impact ejecta.

  1. 3D Arrangement of Slip Systems in Non-Plane Strain: Experimental Plastic Deformation of Fine-Grained Limestone

    NASA Astrophysics Data System (ADS)

    Llana-Funez, S.; Rutter, E. H.

    2006-12-01

    The condition of simultaneous operation of five slip systems to produce homogeneous deformation by intracrystalline plasticity in polycrystalline aggregates is frequently simplified when applied to studying deformation in nature by considering other deformation mechanisms that relax the strict geometric condition. Insufficient knowledge of how these complementary mechanisms interact and accommodate geometrically non-plane strain situations obscure somehow subsequent interpretation of slip patterns in relation to principal strain axes. We ran an experimental program isolating intracrystalline plasticity from other deformation mechanisms with the aim of testing the effect of non-plane strain geometries in the 3D arrangement of crystallographic elements from which we inferred the orientation of active slip systems. We use a fine grained polycrystalline aggregate (Solnhofen Limestone), naturally doped at grain boundaries with organic matter preventing grain growth, that deforms plastically at the experimental conditions used (600 °C, 200 MPa confining pressure and 10^{- 4}s-1 strain rates). To maximize the number of strain geometries we used different experimental configurations (axi-symmetric shortening and extension, and direct shear) and also study in detail volumes where deformation is heterogeneous but still relatively simple. The aim of the work is to relate strain geometry and the development of crystallographic fabrics in different strain paths. We produced constrictional, flattening, and nearly plane strain deformations. We were also able to obtain strain geometries where the vorticity axis in a non-coaxial deformation was either perpendicular to the extension direction (as in simple and sub-simple shear) or parallel to it. We measured the crystallographic preferred orientation (CPO) of calcite in deformed specimens by electron back-scattered diffraction techniques (EBSD), which allowed us to scan relatively small areas within already small specimens

  2. Effect of β volume fraction on the dynamic grain growth during superplastic deformation of Ti3Al-based alloys

    NASA Astrophysics Data System (ADS)

    Kim, Ji Sik; Nam, Won Jong; Lee, Chong Soo

    1998-10-01

    The superplastic deformation behavior of Ti3Al based (α 2+β alloy was studied with respect to the volume fraction of α2/β. Three alloys containing 21, 50 and 77% in volume fractions of β exhibited large tensile elongations of over 500% at 970°C with a strain rate of 2.5x10-4 sec-1. The largest elongation was observed in the alloy with 21% of β. As the volume fraction of β phase increased, the flow stress and correspondingly, the strain-rate sensitivity values decreased. Due to the higher diffusivity of Ti in,β phase than in α2 phase, the increase in β volume fraction from 21 % to 77% accelerated the dynamic grain growth, and degraded the superplasticity of the Ti3Al-based alloys. The strain-based grain growth behavior was quantitatively analyzed and incorporated into a constitutive equation. The calculated flow curves are in agreement with the experimental ones in the stable deformation region.

  3. Development of bulk density, total C distribution and OC saturation in fine mineral fractions during paddy soil evolution

    NASA Astrophysics Data System (ADS)

    Wissing, Livia; Kölbl, Angelika; Cao, Zhi-Hong; Kögel-Knabner, Ingrid

    2010-05-01

    Paddy soils are described as important accumulator for OM (Zhang and He, 2004). In southeast China, paddy soils have the second highest OM stocks (Zhao et al, 1997) and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. The paddy soil management is believed to be favorable for accumulation of organic matter, as its content in paddy soils is statistically higher than that of non-paddy soils (Cai, 1996). However, the mechanism of OM storage and the development of OM distribution during paddy soil evolution is largely unknown. The aim of the project is to identify the role of organo-mineral complexes for the stabilization of organic carbon during management-induced paddy soil formation in a chronosequence ranging from 50 to 2000 years of paddy soil use. The soil samples were analysed for bulk density, total organic carbon (TOC) and total inorganic carbon (TIC) concentrations of bulk soils and the concentration of organic carbon as well as the organic carbon stocks of physical soil fractions. First results indicate distinctly different depth distributions between paddy and non-paddy (control) sites. The paddy soils are characterized by relatively low bulk densities in the puddled layer (between 0.9 and 1.3 g cm-3) and high values in the plough pan (1.4 to 1.6 g cm-3) and the non-paddy soils by relatively homogeneous values throughout the profiles (1.3 to 1.4 g cm-3). In contrast to the carbonate-rich non-paddy sites, we found a significant loss of carbonates during paddy soil formation, resulting in decalcification of the upper 20 cm after 100 yr of paddy soil use, and decalcification of the total soil profile in 700, 1000 and 2000 yr old paddy soils. The calculation of the organic carbon stocks of each horizon indicate that paddy sites always have higher values in topsoils compared to non-paddy sites, and show increasing values with increasing soil age. The capacity of fine mineral fractions to preserve OC was calculated according to

  4. Optical dating of Holocene tidal deposits from the southwestern coast of the South Yellow Sea using different grain-size quartz fractions

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Long, Hao; Shen, Ji; Yu, Ge; Liao, Mengna; Yin, Yong

    2017-03-01

    The tidal flat deposit provides ideal sedimentary records for paleoenvironmental studies. Reliable chronology is crucial to utilize this archive for deciphering the history of environmental changes. In this study, we applied optically stimulated luminescence (OSL) dating method to a Holocene tidal flat sequence using both coarse-grained (CG, 90-200 μm) and fine-grained (FG, 4-11 μm) quartz extracts from a sedimentary core (YZ07) in western coast of the South Yellow Sea. The luminescence characteristics of the two grain-size fractions were investigated and then their resulting OSL ages were systematically compared. The results suggested that most tidal flat deposits are well bleached and their FG quartz ages are generally consistent with CG quartz ages, while some samples have CG ages underestimated compared with FG, likely resulted from the K-feldspar contamination for CG quartz. Hence, we applied post-IR OSL dating and pulsed OSL dating techniques; they could overcome the problems caused by feldspar contamination, and yielded identical dates as FG OSL ages. All OSL ages are generally in stratigraphic order; in contrast, the 14C ages are much more disorder and characterized with severe inversions. Finally, the age framework of the tidal flat sequence under this study was constructed based on the 30 OSL ages and one acceptable radiocarbon age. According to the age-depth model, three main periods of sedimentation-rate (SR) variation were identified. These SR changes are probably associated with sea-level rise/fall history, and the depocenter landward/seaward movement as well as the transition of depositional process within the Holocene delta initiation. The depositional environment changes were also reflected in sedimentological features of the tidal flat deposits in our study area.

  5. The role of fine-grained annotations in supervised recognition of risk factors for heart disease from EHRs.

    PubMed

    Roberts, Kirk; Shooshan, Sonya E; Rodriguez, Laritza; Abhyankar, Swapna; Kilicoglu, Halil; Demner-Fushman, Dina

    2015-12-01

    This paper describes a supervised machine learning approach for identifying heart disease risk factors in clinical text, and assessing the impact of annotation granularity and quality on the system's ability to recognize these risk factors. We utilize a series of support vector machine models in conjunction with manually built lexicons to classify triggers specific to each risk factor. The features used for classification were quite simple, utilizing only lexical information and ignoring higher-level linguistic information such as syntax and semantics. Instead, we incorporated high-quality data to train the models by annotating additional information on top of a standard corpus. Despite the relative simplicity of the system, it achieves the highest scores (micro- and macro-F1, and micro- and macro-recall) out of the 20 participants in the 2014 i2b2/UTHealth Shared Task. This system obtains a micro- (macro-) precision of 0.8951 (0.8965), recall of 0.9625 (0.9611), and F1-measure of 0.9276 (0.9277). Additionally, we perform a series of experiments to assess the value of the annotated data we created. These experiments show how manually-labeled negative annotations can improve information extraction performance, demonstrating the importance of high-quality, fine-grained natural language annotations.

  6. Correlation of shape and size of methane bubbles in fine-grained muddy aquatic sediments with sediment fracture toughness

    NASA Astrophysics Data System (ADS)

    Katsman, Regina

    2015-01-01

    Gassy sediments contribute to destabilization of aquatic infrastructure, air pollution, and global warming. In the current study a precise shape and size of the buoyant mature methane bubble in fine-grained muddy aquatic sediment is defined by numerical and analytical modeling, their results are in a good agreement. A closed-form analytical solution defining the bubble parameters is developed. It is found that the buoyant mature bubble is elliptical in its front view and resembles an inverted tear drop in its cross-section. The size and shape of the mature bubble strongly correlate with sediment fracture toughness. Bubbles formed in the weaker sediments are smaller and characterized by a larger surface-to-volume ratio that induces their faster growth and may lead to their faster dissolution below the sediment-water interface. This may prevent their release to the water column and to the atmosphere. Shapes of the bubbles in the weaker sediments deviate further from the spherical configuration, than those in the stronger sediments. Modeled bubble characteristics, important for the acoustic applications, are in a good agreement with field observations and lab experiments.

  7. Polycrystalline silicon films with nanometer-sized dense fine grains formed by flash-lamp-induced crystallization.

    PubMed

    Ohdaira, Keisuke; Ishii, Shohei; Tomura, Naohito; Matsumura, Hideki

    2012-01-01

    Flash lamp annealing (FLA) with millisecond-order pulse duration can crystallize microm-order-thick a-Si films on glass substrates through explosive crystallization (EC), and flash-lamp-crystallized (FLC) poly-Si films consist of densely-packed nanometer-sized fine grains. We investigate the impact of the hydrogen concentration and the defect density of precursor a-Si films on crystallization mechanism and the microstructures of FLC poly-Si films, by comparing chemical-vapor-deposited (CVD) and sputtered precursor a-Si films. Transmission electron microscopy (TEM) observation reveals that FLC poly-Si films with similar periodic microstructures are formed by the FLA of the two kinds of precursor films, meaning no significant influence of hydrogen atoms and defect density on crystallization mechanism. This high flexibility of the properties of precursor a-Si films would contribute to a wide process window to reproducibly form FLC poly-Si films with the particular periodic microstructures.

  8. Microstructural and mechanical effects of strong fine-grained muscovite in soft halite matrix: Shear strain localization in torsion

    NASA Astrophysics Data System (ADS)

    Marques, F. O.; Burlini, L.; Burg, J.-P.

    2011-08-01

    Torsion experiments were performed on polymer jacketed samples of 80% halite + 20% fine mica at 373, 473, and 573 K; a confining pressure of 250 MPa; and a shear strain rate of 3 × 10-4 s-1. The strength of the aggregate depended on temperature, strain rate, mica distribution produced by cold pressing, and mica orientation emerging during experiments. Comparison with synthetic aggregates of pure halite shows that halite-mica mixtures were stronger in all cases. From strain rate stepping tests, we deduced stress exponents of 12 and 10 at 373 and 473 K, respectively, in contrast to values of approximately 4 and 3 for halite at the same temperatures. Strain localized only at 573 K, except for one run at 373 K, and high-strain shear bands formed parallel to the applied shear plane at 573 K. We infer that the strength contrast between halite and mica increased with temperature and promoted strain localization, which occurred where the local mica content was low, while unstrained domains persisted where the locally high mica content formed a strong framework. Mica reorientation and strain softening at 573 K increased with strain, from which we deduce that mica alignment promoted softening. We conclude that small amounts of a strong mineral phase can significantly increase the strength and stress dependence of a rock and that the heterogeneous connectivity between strong grains can trigger shear strain localization.

  9. Seismic characterization of hydrates in faulted, fine-grained sediments of Krishna-Godavari basin: Unified imaging

    NASA Astrophysics Data System (ADS)

    Jaiswal, P.; Dewangan, P.; Ramprasad, T.; Zelt, C. A.

    2012-04-01

    A combination of diffusion and advection in fine grained sediments can create a patchy Bottom Simulating Reflector (BSR) which has little to no apparent correlation with the overlying hydrate distribution. Using 2D seismic data from faulted, clay-rich sediments in the Krishna-Godavari (KG) basin, we show both the hydrate distribution and the BSR structure are fault controlled. Our demonstration hinges upon a kinematically accurate P wave velocity (VP) model which is estimated using a composite traveltime-inversion, depth-migration method in an iterative manner. The flexibility of the method allows simultaneous usage of traveltimes from multiple, discontinuous reflectors. The application begins with a simple VP model from time processing which is reflective of a diffusive, continuous, hydrate- and free gas-bearing system. The application converges in three iterations yielding a final VPmodel which is suggestive of a patchy distribution of hydrates and free gas possibly developing through a combined diffusive-advective system. The depth image corresponding to the final VP model can be interpreted for faults that suggest ongoing tectonism. The BSR appears to be truncated at active faults zones. Both the final VP model and the corresponding depth image can be reconciled with the hydrate distribution and BSR depth at logging/coring sites located ˜250 m away from the line by projecting the sites along the strike direction of the regional faults.

  10. Ichnology of fine-grained mixed carbonate-siliciclastic turbidites, Wood River Formation, Pennsylvanian-Permian south-central Idaho

    SciTech Connect

    Burton, B.R. ); Link, P.K. )

    1991-06-01

    In south-central Idaho, the Wood River Formation (Pennsylvanian-Permian) contains a stratigraphic megacycle over 2,000 m thick that is composed of fine-grained mixed carbonate-siliciclastic turbidites. Complete and partial (Bouma) turbidite structural sequences in these rocks are arranged in upward thinning cycles 15 to 30 m thick in which top-cut-out (Ta-c) turbidite facies in the lower part grade vertically into base-cut-out (Td-f) turbidites in the upper part. These cycles are interpreted to represent the autocyclic lateral migration of turbidite lobes. A mixed trace fossil assemblage of pascichnia and fordinichnia are present in these rocks and can be separated into pre-depositional and post-turbidite ichnocoenoses. Quiet-water, pre-turbidite deposits are dark-colored, laminated, and carbonaceous, and represent anoxic to dysoxic inter-turbidite basinal conditions; they contain only Chondrites traces. Turbidity currents introduced oxygenated bottom water which fostered the temporary development of a post-turbidite ichnocoenose of pascichnia which is best developed in the medial portion of turbidite beds and lobes. Trace fossil tiering shows that a post-turbidite ichnocoenose of fodinichnia also developed, and persisted after the disappearance of pascichnia. Animals that produced the fodinichnial traces probably were part of an autochthonous benthic fauna rather than a short-lived allochthonous fauna. They may have migrated with the slowly avulsing turbidite lobes and exploited allochthonous oxygen and the carbonaceous food supply.

  11. Intelligibility of normal speech I: Global and fine-grained acoustic-phonetic talker characteristics1,2

    PubMed Central

    Bradlow, Ann R.; Torretta, Gina M.; Pisoni, David B.

    2011-01-01

    This study used a multi-talker database containing intelligibility scores for 2000 sentences (20 talkers, 100 sentences), to identify talker-related correlates of speech intelligibility. We first investigated “global” talker characteristics (e.g., gender, F0 and speaking rate). Findings showed female talkers to be more intelligible as a group than male talkers. Additionally, we found a tendency for F0 range to correlate positively with higher speech intelligibility scores. However, F0 mean and speaking rate did not correlate with intelligibility. We then examined several fine-grained acoustic-phonetic talker-characteristics as correlates of overall intelligibility. We found that talkers with larger vowel spaces were generally more intelligible than talkers with reduced spaces. In investigating two cases of consistent listener errors (segment deletion and syllable affiliation), we found that these perceptual errors could be traced directly to detailed timing characteristics in the speech signal. Results suggest that a substantial portion of variability in normal speech intelligibility is traceable to specific acoustic-phonetic characteristics of the talker. Knowledge about these factors may be valuable for improving speech synthesis and recognition strategies, and for special populations (e.g., the hearing-impaired and second-language learners) who are particularly sensitive to intelligibility differences among talkers. PMID:21461127

  12. Microstructure Development and Lateral Distribution of Defects in Ultra-fine Grained Copper Prepared by High-pressure Torsion

    NASA Astrophysics Data System (ADS)

    Procházka, Ivan; Čížek, Jakub; Melikhova, Oksana; Barnovská, Zuzana; Janeček, Miloš; Srba, Ondřej; Kužel, Radomír; Dobatkin, Sergej V.

    A defect study of ultra-fine grained (UFG) Cu prepared by high-pressure torsion (HPT) will be reported. Conventional positron annihilation spectroscopy (PAS) including positron lifetime (PLT) and Doppler broadening (DB) techniques was employed as the main experimental tool. PAS was combined with transmission electron microscopy, X-ray diffraction and Vickers microhardness (HV) measurements. First, lattice defects introduced by HPT were characterized. A very high concentration of defects created during HPT deformation was observed and the two kinds of defects could be identified: dislocations and small vacancy clusters (microvoids). Further investigations were focused on (i) the radial distributions of defects and (ii) the evolution of microstructure during HPT processing. The results of the present study are consistent with an increase of shear strain from the sample centre toward its periphery. Extended lateral mapping of microstructure was performed using HV and DB techniques. The latter one reveals a significant non-uniformity of defect distribution which was less pronounced in the HV measurements.

  13. Quantitative analysis and reduction of the eco-toxicity risk of heavy metals for the fine fraction of automobile shredder residue (ASR) using H2O2.

    PubMed

    Singh, Jiwan; Yang, Jae-Kyu; Chang, Yoon-Young

    2016-02-01

    Automobile shredder residue (ASR) fraction (size <0.25mm) can be considered as hazardous due to presence of high concentrations of heavy metals. Hydrogen peroxide combined with nitric acid has been used for the recovery of heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd and Cr) from the fine fraction of ASR. A sequential extraction procedure has also been used to determine the heavy metal speciation in the fine fraction of ASR before and after treatment. A risk analysis of the fine fraction of ASR before and after treatment was conducted to assess the bioavailability and eco-toxicity of heavy metals. These results showed that the recovery of heavy metals from ASR increased with an increase in the hydrogen peroxide concentration. A high concentration of heavy metals was found to be present in Cbio fractions (the sum of the exchangeable and carbonate fractions) in the fine fraction of ASR, indicating high toxicity risk. The Cbio rate of all selected heavy metals was found to range from 8.6% to 33.4% of the total metal content in the fine fraction of ASR. After treatment, Cbio was reduced to 0.3-3.3% of total metal upon a treatment with 2.0% hydrogen peroxide. On the basis of the risk assessment code (RAC), the environmental risk values for heavy metals in the fine fraction of ASR reflect high risk/medium risk. However, after treatment, the heavy metals would be categorized as low risk/no risk. The present study concludes that hydrogen peroxide combined with nitric acid is a promising treatment for the recovery and reduction of the eco-toxicity risk of heavy metals in ASR.

  14. Connecting the grain-shearing mechanism of wave propagation in marine sediments to fractional order wave equations.

    PubMed

    Pandey, Vikash; Holm, Sverre

    2016-12-01

    The characteristic time-dependent viscosity of the intergranular pore-fluid in Buckingham's grain-shearing (GS) model [Buckingham, J. Acoust. Soc. Am. 108, 2796-2815 (2000)] is identified as the property of rheopecty. The property corresponds to a rare type of a non-Newtonian fluid in rheology which has largely remained unexplored. The material impulse response function from the GS model is found to be similar to the power-law memory kernel which is inherent in the framework of fractional calculus. The compressional wave equation and the shear wave equation derived from the GS model are shown to take the form of the Kelvin-Voigt fractional-derivative wave equation and the fractional diffusion-wave equation, respectively. Therefore, an analogy is drawn between the dispersion relations obtained from the fractional framework and those from the GS model to establish the equivalence of the respective wave equations. Further, a physical interpretation of the characteristic fractional order present in the wave equations is inferred from the GS model. The overall goal is to show that fractional calculus is not just a mathematical framework which can be used to curve-fit the complex behavior of materials. Rather, it can also be derived from real physical processes as illustrated in this work by the example of GS.

  15. Accumulation of arsenic in tissues of rice plant (Oryza sativa L.) and its distribution in fractions of rice grain.

    PubMed

    Rahman, M Azizur; Hasegawa, H; Rahman, M Mahfuzur; Rahman, M Arifur; Miah, M A M

    2007-10-01

    A study was conducted to investigate the accumulation and distribution of arsenic in different fractions of rice grain (Oryza sativa L.) collected from arsenic affected area of Bangladesh. The agricultural soil of study area has become highly contaminated with arsenic due to the excessive use of arsenic-rich underground water (0.070+/-0.006 mg l(-1), n=6) for irrigation. Arsenic content in tissues of rice plant and in fractions of rice grain of two widely cultivated rice varieties, namely BRRI dhan28 and BRRI hybrid dhan1, were determined. Regardless of rice varieties, arsenic content was about 28- and 75-folds higher in root than that of shoot and raw rice grain, respectively. In fractions of parboiled and non-parboiled rice grain of both varieties, the order of arsenic concentrations was; rice hull>bran-polish>brown rice>raw rice>polish rice. Arsenic content was higher in non-parboiled rice grain than that of parboiled rice. Arsenic concentrations in parboiled and non-parboiled brown rice of BRRI dhan28 were 0.8+/-0.1 and 0.5+/-0.0 mg kg(-1) dry weight, respectively while those of BRRI hybrid dhan1 were 0.8+/-0.2 and 0.6+/-0.2 mg kg(-1) dry weight, respectively. However, parboiled and non-parboiled polish rice grain of BRRI dhan28 contained 0.4+/-0.0 and 0.3+/-0.1 mg kg(-1) dry weight of arsenic, respectively while those of BRRI hybrid dhan1 contained 0.43+/-0.01 and 0.5+/-0.0 mg kg(-1) dry weight, respectively. Both polish and brown rice are readily cooked for human consumption. The concentration of arsenic found in the present study is much lower than the permissible limit in rice (1.0 mg kg(-1)) according to WHO recommendation. Thus, rice grown in soils of Bangladesh contaminated with arsenic of 14.5+/-0.1 mg kg(-1) could be considered safe for human consumption.

  16. Tidal River Elbe - a sediment budget for the grain size fraction of medium sand

    NASA Astrophysics Data System (ADS)

    Winterscheid, Axel

    2016-04-01

    Human interventions have a historic and ongoing impact on estuarine sediment budgets across many estuaries worldwide. An early inference was the construction of embankments resulting in a constant loss of intertidal flats. Additionally, settlement activities and large scale land use changes in the upstream catchment areas had also an effect on sediment inflow rates. Today, the navigation channels in estuaries have been deepened for larger and more efficient vessels to reach a well-developed infrastructure of harbors and industrial areas often located far inland. In the past few years and just within the North-East Atlantic, the total annual amount of dredged sediments dumped at sea varied from 80 to 130 million tons (OSPAR Commission). In most estuaries across Europe the resulting human impact on the sediment fluxes and morphodynamics is significant. A good understanding of estuarine processes is essential for determining useful and meaningful measures to mitigate negative effects and to improve the current situation. Maintenance dredging and its environmental effects are therefore in the focus of public attention. Against this background, it is the aim of the presentation to identify and therefore to separate the particular effect that maintenance dredging has on sediment fluxes and budgets in the estuarine environment. Case study is the Tidal River Elbe in Germany, and here we set the focus on the grain size fraction of medium sand. In the past, river engineering measures forced the natural dynamics to form a concentrated stream flow along a fixed channel, except at a number of locations where side channels still exist. In addition to that, the main channel was deepened several times. The last deepening was in 1999/2000. The most significant deepening, however, took place from 1957 to 1962. Until then, an erosion-stable layer of marine clay (in German called "Klei") formed a flat bottom along most sections of the main channel. After removal of this layer of

  17. A long duration of the 16O-rich reservoir in the solar nebula, as recorded in fine-grained refractory inclusions from the least metamorphosed carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Ushikubo, Takayuki; Tenner, Travis J.; Hiyagon, Hajime; Kita, Noriko T.

    2017-03-01

    Oxygen isotope ratios and corresponding 26Al-26Mg isotope systematics of refractory inclusions from the least metamorphosed carbonaceous chondrites, Acfer 094 (C-ungrouped 3.00) and Yamato 81020 (CO3.05), were measured with an ion microprobe. Most of the samples are fine-grained refractory inclusions which are considered as condensates from high temperature solar nebular gas. The refractory inclusions consistently exhibit 16O-enriched signatures among their interior phases (spinel, melilite, and high-Ca pyroxene), as well as phases within their rim structures (spinel, high-Ca pyroxene, and adjacent anorthite). This observation indicates that aggregated refractory condensates and the formation of rim structures occurred in the same 16O-rich environment. Evidence for mass-dependent isotopic fractionation in oxygen and magnesium, which would indicate a later flash heating process, was not observed in rims. All oxygen isotope data from fine-grained CAIs are distributed between the Carbonaceous Chondrite Anhydrous Mineral (CCAM) line and the Primitive Chondrule Mineral (PCM) regression line based on oxygen isotope data from the Acfer 094 chondrules. The inferred initial 26Al/27Al ratios, (26Al/27Al)0, of spinel-melilite-rich CAIs are (4.08 ± 0.75) × 10-5 to (5.05 ± 0.18) × 10-5 (errors are 2σ), which are slightly lower than the canonical value of 5.25 × 10-5. As there is no petrologic evidence for re-melting after condensation, the lower (26Al/27Al)0 values of these CAIs indicate either they formed up to ∼0.3 Ma after canonical CAIs or they formed before 26Al was homogeneously distributed in the solar nebula. A pyroxene-anorthite-rich CAI, G92, has an 16O-rich signature like other CAIs but also has an order-of-magnitude less 26Mg-excess in anorthite, corresponding to a (26Al/27Al)0 of (5.21 ± 0.54) × 10-6. As there is no evidence for a later Mg isotopic disturbance, G92 anorthite is interpreted to have formed by interaction with 16O-rich nebular gas at 2-3 Ma

  18. An assessment of geochemical preparation methods prior to organic carbon concentration and carbon isotope ratio analyses of fine-grained sedimentary rocks

    NASA Astrophysics Data System (ADS)

    KöNitzer, Sven F.; Leng, Melanie J.; Davies, Sarah J.; Stephenson, Michael H.

    2012-09-01

    This study summarizes organic carbon isotope (δ13C) and total organic carbon (TOC) data from a series of tests undertaken to provide an appropriate methodology for pre-analysis treatment of mudstones from an Upper Carboniferous sedimentary succession, in order to develop a consistent preparation procedure. The main treatments involved removing both inorganic carbonate and hydrocarbons (which might be extraneous) before δ13C and TOC analysis. The results show that decarbonating using hydrochloric acid causes significant reduction in δ13C and total carbon (TC) of the bulk material due to the removal of inorganic carbonate. These changes are most pronounced where soluble calcium carbonate (rather than Ca-Mg-Fe carbonate) is present. Deoiled samples show only slightly higher mean δ13C where visible bitumen was extracted from the bulk sample. Moreover, the isotopic signatures of the extracts are closely correlated to those of their respective bulk samples, suggesting that small yields of hydrocarbons were generated in situ with no isotopic fractionation. In addition, further δ13C and TC analyses were performed on samples where mixing of oil-based drilling mud with brecciated core material had been undertaken. Brecciated mudstone material did not display distinct isotopic signals compared to the surrounding fine-grained material. Overall we show that the most accurate assessment of bulk organic carbon isotopes and concentration in these samples can be achieved through decarbonating the material prior to measurement via the `rinse method'. However, our results support recent findings that pre-analysis acid treatments can cause variable and unpredictable errors in δ13C and TOC values. We believe that, despite these uncertainties, the findings presented here can be applied to paleoenvironmental studies on organic matter contained within sedimentary rocks over a range of geological ages and compositions.

  19. Comparisons of Remote Sensing Retrievals and in situ Measurements of Aerosol Fine Mode Fraction during ACE-Asia

    NASA Technical Reports Server (NTRS)

    Gasso, Santiago; O'Neill, Norm

    2006-01-01

    We present sunphotometer-retrieved and in situ fine mode fractions (FMF) measured onboard the same aircraft during the ACE-Asia experiment. Comparisons indicate that the latter can be used to identify whether the aerosol under observation is dominated by a mixture of modes or a single mode. Differences between retrieved and in situ FMF range from 5-20%. When profiles contained multiple layers of aerosols, the retrieved and measured FMF were segregated by layers. The comparison of layered and total FMF from the same profile indicates that columnar values are intermediate to those derived from layers. As a result, a remotely sensed FMF cannot be used to distinguish whether the aerosol under observation is composed of layers each with distinctive modal features or all layers with the same modal features. Thus, the use of FMF in multiple layer environments does not provide unique information on the aerosol under observation.

  20. Transition in magnetic fabric types in progressively deformed, fine-grained sedimentary rocks of Central Armorica (Brittany, France)

    NASA Astrophysics Data System (ADS)

    Haerinck, Tom; Hirt, Ann M.; Debacker, Timothy N.; Sintubin, Manuel

    2014-05-01

    The anisotropy of magnetic susceptibility (AMS) of progressively deformed, fine-grained sedimentary rocks is determined for different tectonometamorphic settings in Central Armorica (Brittany, France). Low-temperature AMS and high-field torque magnetometry on a representative selection of samples indicate that the magnetic fabric is dominantly paramagnetic and the ferromagnetic (s.l.) contribution can be neglected. The AMS documents a progressive transition of intermediate fabrics to tectonic fabrics and increasingly stronger developed tectonic fabrics. An integrated magnetic-mineralogical approach is performed in order to assess whether we can use this evolution as a quantitative indicator for the intensity of cleavage development in Central Armorica. During the magnetic fabric transition, the maximum susceptibility axis (K1) remains stationary oriented parallel to the bedding - cleavage intersection, whereas the minimum susceptibility axis (K3) orientation distribution changes from a moderate girdle distribution in the intermediate fabric types, to a strongly clustered distribution parallel to the cleavage pole for the tectonic fabric types. A Woodcock two-axis ratio plot is used to evaluate this change in K3 distribution. This shows a regional pattern with intermediate fabrics in the southern part of Central Armorica and tectonic fabrics in the northern part of Central Armorica. Quantitative analysis of the observed magnetic fabrics shows that the fabric transition described above is accompanied by an evolution from prolate susceptibility ellipsoids with a relatively low degree of anisotropy to oblate ellipsoid with an increasingly higher degree of anisotropy. In a graph of the shape parameter T against the corrected degree of anisotropy PJ, this evolution has a hockey-stick shaped pattern with the vertical branch reflecting the actual transition from intermediate to tectonic fabric type and the horizontal branch reflecting progressively stronger developed

  1. Morphobathymetric analysis of the large fine-grained sediment waves over the Gulf of Valencia continental slope (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Ribó, Marta; Puig, Pere; Muñoz, Araceli; Lo Iacono, Claudio; Masqué, Pere; Palanques, Albert; Acosta, Juan; Guillén, Jorge; Gómez Ballesteros, María

    2016-01-01

    Detailed analysis of recently acquired swath bathymetry, together with high-resolution seismic profiles and bottom sediment samples, revealed the presence of large-scale fine-grained sediment waves over the Gulf of Valencia continental slope. As many other deep-water sediment waves, these features were previously attributed to gravitational slope failure, related to creep-like deformation, and are here reinterpreted as sediment wave fields extending from 250 m depth to the continental rise, at 850 m depth. Geometric parameters were computed from the high-resolution multibeam dataset. Sediment wave lengths range between 500 and 1000 m, and maximum wave heights of up to 50 m are found on the upper slope, decreasing downslope to minimum values of 2 m high. Sediment waves on the lower part of the slope are quasi-stationary vertically accreting, whereas they show an upslope migrating pattern from the mid-slope to the upper part of the continental slope. High-resolution seismic profiles show continuous internal reflectors, with sediment waves merging down-section and sediment wave packages decreasing in thickness downslope. These sediment packages are thicker on the crest of each individual sediment wave and thinner on the downslope flank. 210Pb analyses conducted on sediment cores collected over the sediment wave fields also indicate slightly higher sediment accumulation rates on the wave crests. Sediment wave formation processes have been inferred from contemporary hydrodynamic observations, which reveal the presence of near-inertial internal waves interacting with the Gulf of Valencia continental slope. Internal wave activity is suggested to be the preferential mechanism for the transport and deposition of sediment, and the maintenance of the observed sediment wave fields.

  2. Removal of contaminants from fine grained soils using electrokinetic (EK) flushing. Final report, September 30, 1987--June 30, 1993

    SciTech Connect

    Reed, B.E.; Berg, M.T.

    1993-10-01

    Recently, attention has focused on developing cost effective techniques to remove inorganic contaminants from soils in-situ. For most in-situ techniques hydraulic pressure is used to disperse the chemical additives and collect the contaminated groundwater. In-situ treatment technologies have had success at sites containing sandy soils but have not shown much promise for soils with large amounts of clay and silt. This is due primarily to difficulty in transporting groundwater, contaminants, and chemical additives through the subsurface. Unfortunately, soils high in clay and silt are known to sequester large quantities of inorganic and organic contaminants. Thus, soils having low hydraulic conductivity`s are generally efficient in sequestering pollutants but are resistant to standard in-situ remediation techniques because of the difficulty in transporting groundwater and contaminants. A candidate technology for the in-situ remediation of low permeability soils is electrokinetic (EK) soil flushing. In EK soil flushing, groundwater and contaminants are transported under an a plied voltage. The transport of groundwater electroosmotically does not depend directly on the soil`s hydraulic conductivity. Thus, soils that would otherwise require excavation and treatment can be remediated in-situ if electrokinetics is used as the driving force for liquid and contaminant transport. This report details the results from work conducted on the use of EK soil flushing to remediate a fine grained soil contaminated with lead. The first portion of the experimental work entailed soil collection and characterization, soil adsorption and desorption of lead, and EK reactor construction and testing. The second phase of the research consisted of investigating the efficacy of using EK soil flushing on an actual soil using bench-scale EK reactors. For the second phase of the research the affect of initial conditions on the efficiency of EK soil flushing was studied.

  3. Sources and ages of fine-grained sediment to streams using fallout radionuclides in the Midwestern United States.

    PubMed

    Gellis, Allen C; Fuller, Christopher C; Van Metre, Peter C

    2017-06-01

    Fallout radionuclides, (7)Be and (210)Pbex, sampled in bed sediment for 99 watersheds in the Midwestern region of the United States and in 15 samples of suspended sediment from 3 of these watersheds were used to partition upland from channel sources and to estimate the age or the time since the surface-derived portion of sediment was on the land surface (0-∼1 year). Channel sources dominate: 78 of the 99 bed material sites (79%) have >50% channel-derived sediment, and 9 of the 15 suspended-sediment samples (60%) have >50% channel-derived sediment. (7)Be was detected in 82 bed sediment samples and all 15 suspended-sediment samples. The surface-derived portion of 54 of the 80 (68%) streams with detectable (7)Be and (210)Pbex were ≤ 100 days old and the surface-derived portion of all suspended-sediment samples were ≤ 100 days old, indicating that surface-derived fine-grained sediment moves rapidly though these systems. The concentrations of two hydrophobic pesticides-DDE and bifenthrin-are correlated with the proportion of surface-derived sediment, indicating a link between geomorphic processes and particle-associated contaminants in streams. Urban areas had the highest pesticide concentrations and the largest percentage of surface-derived sediment. Although the percentage of surface-derived sediment is less than channel sources at most of the study sites, the relatively young age of the surface-derived sediment might indicate that management actions to reduce sediment contamination where the land surface is an important source could have noticeable effects.

  4. Geochemical imprint of depositional conditions on organic matter in laminated-Bioturbated interbeds from fine-grained marine sequences

    USGS Publications Warehouse

    Pratt, L.M.; Claypool, G.E.; King, J.D.

    1986-01-01

    Laminated organic-rich shales are interbedded at a scale of centimeters to a few meters with bioturbated organic-poor mudstones or limestones in some fine-grained marine sequences. We have analyzed the organic matter in pairs of laminated/bioturbated interbeds from Cretaceous and Devonian rocks deposited in epicontinental and oceanic settings for the purpose of studying the influence of depositional and early diagenetic environment on the organic geochemical properties of marine shales. Results of these analyses indicate that for rocks that are still in a diagenetic stage of thermal alteration, the relative abundance of biomarker compounds and specific biomarker indices can be useful indicators of depositional and early diagenetic conditions. Pristane/phytane ratios are generally highest for laminated rocks from epicontinental basins and appear to reflect the input of isoprenoid precursors more than oxygenated versus anoxic depositional conditions. The thermally immature laminated rocks are characterized by relatively high contents of 17??(H), 21??(H)-hopanes, hopenes, sterenes and diasterenes, and by strong predominance of the 22R over 22S homohopane isomers. Thermally immature bioturbated samples are characterized by absence of the ??,??-hopanes, by low contents of both saturated and unsaturated polycyclic hydrocarbons, and by slight or no predominance of the 22R over 22S homohopane isomers. There are less obvious compositional differences between the saturated hydrocarbons in the laminated and bioturbated units from the thermally mature sequences. For both the thermally mature and immature laminated samples, the degree of isomerization at the 22C position for hopanes and at the 20C position for steranes is generally consistent with the degree of thermal maturity interpreted from other properties of the organic matter. The bioturbated samples, however, exhibit inconsistent and anomalously high degrees of isomerization for the homohopanes, resulting either from

  5. Monitoring Fine-Grained Sediment in the Colorado River Ecosystem, Arizona - Control Network and Conventional Survey Techniques

    USGS Publications Warehouse

    Hazel, Joseph E.; Kaplinski, Matt; Parnell, Roderic A.; Kohl, Keith; Schmidt, John C.

    2008-01-01

    In 2002, fine-grained sediment (sand, silt, and clay) monitoring in the Colorado River downstream from Glen Canyon Dam was initiated to survey channel topography at scales previously unobtainable in this canyon setting. This report presents the methods used to establish the high-resolution global positioning system (GPS) control network required for this effort as well as the conventional surveying techniques used in the study. Using simultaneous, dual-frequency GPS vector-based methods, the network points were determined to have positioning accuracies of less than 0.03 meters (m) and ellipsoidal height accuracies of between 0.01 and 0.10 m at a 95-percent degree of confidence. We also assessed network point quality with repeated, electronic (optical) total-station observations at 39 points for a total of 362 measurements; the mean range was 0.022 m in horizontal and 0.13 in vertical at a 95-percent confidence interval. These results indicate that the control network is of sufficient spatial and vertical accuracy for collection of airborne and subaerial remote-sensing technologies and integration of these data in a geographic information system on a repeatable basis without anomalies. The monitoring methods were employed in up to 11 discrete reaches over various time intervals. The reaches varied from 1.3 to 6.4 kilometers in length. Field results from surveys in 2000, 2002, and 2004 are described, during which conventional surveying was used to collect more than 3000 points per day. Ground points were used as checkpoints and to supplement areas just below or above the water surface, where remote-sensing data are not collected or are subject to greater error. An accuracy of +or- 0.05 m was identified as the minimum precision of individual ground points. These results are important for assessing digital elevation model (DEM) quality and identifying detection limits of significant change among surfaces generated from remote-sensing technologies.

  6. Numerical simulation of a fine-grained denitrification layer for removing septic system nitrate from shallow groundwater

    NASA Astrophysics Data System (ADS)

    MacQuarrie, Kerry T. B.; Sudicky, Edward A.; Robertson, William D.

    2001-11-01

    One of the most common methods to dispose of domestic wastewater involves the release of septic effluent from drains located in the unsaturated zone. Nitrogen from such systems is currently of concern because of nitrate contamination of drinking water supplies and eutrophication of coastal waters. It has been proposed that adding labile carbon sources to septic distribution fields could enhance heterotrophic denitrification and thus reduce nitrate concentrations in shallow groundwater. In this study, a numerical model which solves for variably saturated flow and reactive transport of multiple species is employed to investigate the performance of a drain field design that incorporates a fine-grained denitrification layer. The hydrogeological scenario simulated is an unconfined sand aquifer. The model results suggest that the denitrification layer, supplemented with labile organic carbon, may be an effective means to eliminate nitrogen loading to shallow groundwater. It is also shown that in noncalcareous aquifers, the denitrification reaction may provide sufficient buffering capacity to maintain near neutral pH conditions beneath and down gradient of the drain field. Leaching of excess dissolved organic carbon (DOC) from the denitrification layer is problematic, and causes an anaerobic plume to develop in simulations where the water table is less than 5-6 m below ground surface; this anaerobic plume may lead to other down gradient changes in groundwater quality. A drain field and denitrification layer of smaller dimensions is shown to be just as effective for reducing nitrate, but has the benefit of reducing the excess DOC leached from the layer. This configuration will minimize the impact of wastewater disposal in areas where the water table is as shallow as 3.5 m.

  7. TEM/AEM characterization of fine-grained clay minerals in very-low-grade rocks: Evaluation of contamination by EMPA involving celadonite family minerals

    SciTech Connect

    Li, Gejing; Peacor, D.R.; Coombs, D.S.; Kawachi, Y.

    1996-12-31

    Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very fine-grained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.

  8. Analysis of Organic Anionic Surfactants in Fine and Coarse Fractions of Freshly Emitted Sea Spray Aerosol

    SciTech Connect

    Cochran, Richard E.; Laskina, Olga; Jayarathne, Thilina; Laskin, Alexander; Laskin, Julia; Lin, Peng; Sultana, Camile M.; Lee, Christopher; Moore, Kathryn A.; Cappa, Christopher; Bertram, Timothy; Prather, Kimberly; Grassian, Vicki H.; Stone, Elizabeth

    2016-02-01

    The inclusion of organic compounds in freshly emitted sea spray aerosol (SSA) has been shown to be size-dependent, with an increasing organic fraction in smaller particles. Defining the molecular composition of sea spray aerosol has proven challenging, due to the mix of continental and background particles even in remote marine environments. Here we have used electrospray ionization-high resolution mass spectrometry in negative ion mode to identify organic compounds in nascent sea spray collected throughout a 25-day mesocosm experiment. Over 280 organic compounds from ten major homologous series were identified. These compounds were operationally defined as molecules containing a hydrophobic alkyl chain with a hydrophilic head group making them surface active. The most abundant class of molecules detected were saturated (C8–C24) and unsaturated (C12–C22) fatty acids. Fatty acid derivatives (including saturated oxo-fatty acids (C5–C18) and saturated hydroxy-fatty acids (C5–C18) were also identified. Interestingly, anthropogenic influences on SSA from the seawater were observed in the form of sulfate (C2–C7, C12–C17) and sulfonate (C16–C22) species. During the mesocosm, the distributions of molecules within each homologous series were observed to respond to variations among the levels of phytoplankton and bacteria in the seawater, indicating an important role of biological processes in determining the composition of SSA.

  9. K0-Behavior of Normally Consolidated Fine-Grained Soils during One-Dimensional Secondary Compression Aging and the Quantitative Prediction of the Quasi-Preconsolidation Effect.

    DTIC Science & Technology

    1986-01-01

    Plastic Kaolinite and three Agsco novaculite, were allowed to age a minimum of 14 days under 2 tsf vertical stress while the Ko-condition was maintained and...16 3.1 Introduction ................................ 16 3.2 Edgar Plastic Kaolinite ....................... 17 3.3 Novaculite...system are provided. "’Six normally consolidated fine-grained specimens, three Edjar Plastic Kaolinite and three Agsco novaculite, were allowed to

  10. Chemical diversity among fine-grained soils at Gale (Mars): a chemical transition as the rover is approaching the Bagnold Dunes?

    NASA Astrophysics Data System (ADS)

    Cousin, Agnès; Forni, Olivier; Meslin, Pierre-Yves; Schroeder, Susanne; Gasnault, Olivier; Bridges, Nathan; Ehlmann, Bethany; Maurice, Sylvestre; Wiens, Roger

    2016-04-01

    The ChemCam instrument has the capability to study the chemical composition of soils at a sub-millimeter scale, thus providing an unpreceedented spatial resolution for their study. More than 300 soils have been sampled so far with ChemCam and these targets are analyzed frequently in order to monitor any change in composition along the traverse. Detailed chemical analysis as a function of grain size is of great importance in order to better constrain soils formation. Curiosity is approaching the Bagnold Dunes, the first active dune field accessible for in-situ analyses. One of the main goals is to determine or constrain the dune material chemistry as well as its provenance. This study is focusing on recent soils analyzed when ap-proaching the dunes, for a comparison with previous soil targets, and with dunes specifically. Chemical composition of fine-grained soils as we approach the Bagnold Dunes has been compared with previous fine-grained soils analyzed along the traverse. These new soils have an average sum of oxides that is significantly higher than what has been previously analyzed. This would suggest that these soils are less hydrated and probably less altered than previous ones.An enrichment in SiO2, FeO and alkali is also observed in these new fine-grained soils, which could be related to a contamination by local rocks due to erosion. Some coarser grains could correspond to an olivine component. This analysis is on-going and will be detailed as the dedicated Bagnold Dunes campaign starts. We will also report in the hydratation level of the dunes.

  11. Vertical migration of fine-grained sediments from interior to surface of seabed driven by seepage flows-`sub-bottom sediment pump action'

    NASA Astrophysics Data System (ADS)

    Zhang, Shaotong; Jia, Yonggang; Wen, Mingzheng; Wang, Zhenhao; Zhang, Yaqi; Zhu, Chaoqi; Li, Bowen; Liu, Xiaolei

    2017-02-01

    A scientific hypothesis is proposed and preliminarily verified in this paper: under the driving of seepage flows, there might be a vertical migration of fine-grained soil particles from interior to surface of seabed, which is defined as `sub-bottom sediment pump action' in this paper. Field experiments were performed twice on the intertidal flat of the Yellow River delta to study this process via both trapping the pumped materials and recording the pore pressures in the substrate. Experimental results are quite interesting as we did observe yellow slurry which is mainly composed of fine-grained soil particles appearing on the seabed surface; seepage gradients were also detected in the intertidal flat, under the action of tides and small wind waves. Preliminary conclusions are that `sediment pump' occurs when seepage force exceeds a certain threshold: firstly, it is big enough to disconnect the soil particles from the soil skeleton; secondly, the degree of seabed fluidization or bioturbation is big enough to provide preferred paths for the detached materials to migrate upwards. Then they would be firstly pumped from interior to the surface of seabed and then easily re-suspended into overlying water column. Influential factors of `sediment pump' are determined as hydrodynamics (wave energy), degree of consolidation, index of bioturbation (permeability) and content of fine-grained materials (sedimentary age). This new perspective of `sediment pump' may provide some implications for the mechanism interpretation of several unclear geological phenomena in the Yellow River delta area.

  12. Dating loess with high temperature IRSL signals from polymineral fine grains: luminescence characteristics and comparison with conventional techniques

    NASA Astrophysics Data System (ADS)

    Thiel, C.; Buylaert, J.-P.; Murray, A. S.; Tsukamoto, S.; Jain, M.; Frechen, M.

    2009-04-01

    It is well known that loess deposits contain detailed terrestrial archives of palaeoenvironmental changes. Unfortunately, loess sequences often lack a reliable absolute chronology, and thus these changes are difficult to constrain in time. Luminescence dating is the technique of choice to address this issue. Quartz and feldspar are the most commonly used dosimeters in luminescence dating. The age range of standard quartz OSL is usually limited by the saturation level of ~200 Gy (corresponding to ~50 ka). In contrast, the age range of feldspar IRSL signals - which usually have a more extended growth curve (up to ~2000 Gy) - is hampered by anomalous fading for which a reliable correction is still not available. Recently, Thomsen et al. (2008) identified several laboratory-induced feldspar signals which show less anomalous fading than the standard IRSL signal stimulated at 50°C. Based on this work, Buylaert et al. (accepted) tested a post-IR IR signal, i.e. IR bleach at 50°C and subsequent IRSL measurement at 225°C, and observed significantly lower fading rates in nature for a number of coarse-grained K-feldspar samples. In this study we explore the possibility of using such a post-IR IR signal from polymineral fine grains extracted from loess. Murray et al. (accepted) showed that a more stringent preheat treatment (320°C for 60 s) can be safely used for feldspar; as a result, we have been able to use a post-IR IR measurement temperature of 290°C, higher than that in the study of Buylaert et al. (accepted), with the expectation that this might further reduce the observed fading rate. The results of the elevated temperature IRSL signal fading measurements clearly indicate a significantly lower fading rate (g2days values typically 1-1.5 %/decade) than the standard IRSL measured at 50°C (g2days values typically 3 %/decade). Results of the performance in the SAR protocol (recycling ratios, recuperation and dose recovery) are very encouraging (measured dose within 15

  13. Algal blooms and "Marine snow": Mechanisms that enhance preservation of organic carbon in ancient fine-grained sediments

    USGS Publications Warehouse

    Macquaker, J.H.S.; Keller, M.A.; Davies, S.J.

    2010-01-01

    Combined petographic and geochemical methods are used to investigate the microfabrics present in thin sections prepared from representative organic carbon-rich mudstones collected from three successions (the Kimmeridge Clay Formation, the Jet Rock Member of the Whitby Mudstone Formation, and the pebble shale and Hue Shale). This study was initiated to determine how organic carbon-rich materials were being delivered to the sediment-water interface, and what happened to them after deposition, prior to deep burial. Analyses of the fabrics present shows that they exhibit many common attributes. In particular they are all: (1) highly heterogeneous on the scale of a thin section, (2) organized into thin beds (< 10 mm thick) composed mainly of mineral mixtures of fine-grained siliciclastic detritus and carbonate materials, and (3) contain significant concentrations of organic carbon, much of which is organized into laminasets that contain abundant organomineralic aggregates and pellets. In addition, framboidal pyrite (range of sizes from < 20 urn to < 1 ??m) and abundant agglutinated foraminifers are present in some units. The individual beds are commonly sharp-based and overlain by thin, silt lags. The tops of many of the beds have been homogenized and some regions of the pelleted laminasets contain small horizontal burrows. The organomineralic aggregates present in these mudstones are interpreted to be ancient examples of marine snow. This marine snow likely formed in the water column, particularly during phytoplankton blooms, and was then transported rapidly to the seafloor. The existence of the thin beds with homogenized tops and an in-situ infauna indicates that between blooms there was sufficient oxygen and time for a mixed layer to develop as a result of sediment colonization by diminutive organisms using either aerobic or dysaerobic metabolic pathways. These textures suggest that the constituents of these mudstones were delivered neither as a continuous rain of

  14. Key parameters for low-grade fine-grained iron ore valorization: lower environmental impact through reduced waste.

    NASA Astrophysics Data System (ADS)

    Wagner, Christiane; Orberger, Beate; Tudryn, Alina; Baptiste, Benoît; Wirth, Richard; Morgan, Rachel; Miska, Serge

    2016-04-01

    In low-grade banded iron formations (BIFs), a large part of the iron is related to micro- and nano- metric iron-bearing inclusions within quartz and/or carbonates, mainly dolomite (~ 20 to 50 μm). Low-grade fine grained iron ore present two types of environmental risks: a) they are often stocked as tailings. For example, the recent disaster (5th of November 2015) in the Minas Gerais district, Brazil, was caused by the collapse of the Fundão tailings dam at an open cast mine; b) during beneficiation significant amounts of dust are generated also leading to metal loss. A laminated BIF studied from a drill core at Àguas Claras Mine, Quadrilátero Ferrífero, Brazil, contains 26.71 wt. % total iron, 0.2 wt. % SiO2, 0.32 wt.% MnO, 15.46 wt. % MgO, 22.32 wt.% CaO, 0.09 wt. % P2O5, < 0.05 wt. % Al2O3, 0.15 wt. % H2O and 34.08 wt. % CO2. Environmental hazardous elements are present as traces (As: 3-20 ppm, Cd: 0-0.7 ppm; Cr: 0.05-60 ppm, Pb: up to 55 ppm; U: up to 8 ppm). Dolomite and quartz bands alternate with hematite bands. Raman spectroscopy, X-ray diffraction and FIB-TEM analyses reveal that the micro- and nano- metric inclusions in dolomite are hematite and minor goethite, partly occurring as clusters in voids. Curie Balance analyses were carried out at different heating steps and temperatures on whole rock samples and a synthetic mix of decarbonated sample and pure dolomite. X-ray diffraction on the products of the heating experiments shows that that hematite is stable and new phases: magnesioferrite (MgFe2O4), lime (CaO), periclase (MgO), portlandite (Ca(OH)2) and srebrodoskite (Ca2Fe2O5) were formed between 680 °C and 920 °C. These findings promote the economic use of low grade ores rather than their stockpiling as tailings. The presence of OH-bearing goethite reduces the sintering temperature. After having separated coarse hematite from barren dolomite and quartz, a low temperature sintering of the inclusion-bearing dolomite/quartz leads to transformations

  15. Effects of grain size and humidity on fretting wear in fine-grained alumina, Al{sub 2}O{sub 3}/TiC, and zirconia

    SciTech Connect

    Krell, A.; Klaffke, D.

    1996-05-01

    Friction and wear of sintered alumina with grain sizes between 0.4 and 3 {micro}m were measured in comparison with Al{sub 2}O{sub 3}/TiC composites and with tetragonal ZrO{sub 2} (3 mol% Y{sub 2}O{sub 3}). The dependence on the grain boundary toughness and residual microstresses is investigated, and a hierarchical order of influencing parameters is observed. In air, reduced alumina grain sizes improve the micromechanical stability of the grain boundaries and the hardness, and reduced wear is governed by microplastic deformation, with few pullout events. Humidity and water slightly reduce the friction of all of the investigated ceramics. In water, this effect reduces the wear of coarser alumina microstructures. The wear of aluminas and of the Al{sub 2}O{sub 3}/TiC composite is similar; it is lower than observed in zirconia, where extended surface cracking occurs at grain sizes as small as 0.3 {micro}m.

  16. Determining the turnover time of mercury-contaminated fine-grained sediment in the gravel bed of the South River, Virginia using Pb-210, Be-7 and Cs-137

    NASA Astrophysics Data System (ADS)

    Pomraning, S. N.; Pizzuto, J. E.; Jurk, D.

    2010-12-01

    Fine-grained sediment and associated contaminants mediate important geochemical cycles in the hyporheic zone of gravel-bed rivers, but the turnover time of fine particles in these environments has rarely been measured. We analyzed the activities of Pb-210, Cs-137 and Be-7 in samples from four cores obtained on November 2, 2009 from a representative section of the bed composed of a mixture of sand, pebbles, and cobbles. The median grain size is 25.5 mm, the 84th percentile grain diameter is 57.8 mm, and 5.7% of the bed is composed of sediment smaller than 2 mm (sand sized or smaller sediment). The cores were sampled at five centimeter depth increments and each sample was sieved to extract the silt- and clay-sized particles. After freeze-drying the samples, equivalent depth intervals from all the cores were combined to yield a spatially averaged sample with depth intervals of 0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm and 20-25 cm. Radionuclide activities were measured using a Canberra low energy germanium detector (model GL2020R). Activities of Pb-210 at the time of deposition were estimated from suspended sediment samples collected during a high flow event (recurrence interval 0.24 years) that occurred on November 13, 2009. At a depth of 2.5 cm, the Pb-210 dating indicates that the silt-clay fine fraction of the hyporheic zone is 21.3 years old; fine sediment at a depth of 17.5 cm is 29.3 years old. Assuming that the time-averaged bed elevation has not changed over time, and that sediment at depth is periodically removed by scour and subsequently replaced by fill, methods of reservoir theory suggest that the turnover time of silt- and clay-sized particles in the hyporheic zone is about two years. Because deep scour events are apparently relatively rare, approximately 21 years are required to rework 90% of the bed. These results have important implications for contaminant remediation. Even if all ongoing sources of mercury to the South River are removed, several decades

  17. Uranium resources in fine-grained carbonaceous rocks of the Great Divide Basin, south-central Wyoming. National Uranium Resource Evaluation

    SciTech Connect

    Burger, J.A.; Roe, L.M. II; Hacke, C.M.; Mosher, M.M.

    1982-11-01

    The uranium resources of the fine-grained carbonaceous rocks of the Great Divide Basin in southern Wyoming were assessed. The assessment was based primarily on data from some 600 boreholes. The data included information from geophysical logs, lithologic logs and cores, and drill cuttings. The cores and cuttings were analyzed for chemical U/sub 3/O/sub 8/, radiometric U, Th and trace elements. Selected samples were examined by thin section, sieve analysis, x-ray, SEM, ion probe, and alpha track methods. The uranium is associated with fine-grained carbonaceous shales, siltstones, mudstones, and coals in radioactive zones 5 to 50 ft thick that are continuous over broad areas. These rocks have a limited stratigraphic range between the Red Desert tongue of the Wasatch Formation and the lower part of the Tipton tongue of the Green River Formation. Most of this uranium is syngenetic in origin, in part from the chelation of the uranium by organic material in lake-side swamps and in part as uranium in very fine detrital heavy minerals. The uraniferous fine-grained carbonaceous rocks that exceed a cutoff grade of 100 ppM eU/sub 3/O/sub 8/ extend over an area of 542 mi/sup 2/ and locally to a depth of approximately 2000 ft. The uraniferous area is roughly ellipical and embraces the zone of change between the piedmont and alluvial-fan facies and the lacustrine facies of the intertonguing Battle Spring, Wasatch, and Green River Formations. About 1.05 x 10/sup 6/ tons U/sub 3/O/sub 8/, based on gross-gamma logs not corrected for thorium, are assigned to the area in the first 500 ft; an estimated 3.49 x 10/sup 6/ tons are assigned to a depth of 1000 ft. These units also contain a substantial thorium resource that is also associated with fine-grained rocks. The thorium-to-uranium ratio generally ranges between 1 and 4. A thorium resource of 3.43 x 10/sup 6/ tons to a depth of 500 ft is estimated for the assessment area. 5 figures, 3 tables.

  18. A Bi-Modal Distribution of ALHA77307 Matrix Olivine: Evidence for Fine-Grained Mixing from Multiple Reservoirs in the CO Formation Zone

    NASA Technical Reports Server (NTRS)

    Frank, D.; Zolensky, Michael E.; Brearley, A.; Le, L.

    2011-01-01

    The CO 3.0 chondrite ALHA77307 is thought to be the least metamorphosed of all the CO chondrites [1]. As such, the fine-grained (<30 m) olivine found in its matrix is a valuable resource for investigating the CO formation environment since its compositions should be primary. In the CO matrix, we indeed find a wide range of major element compositions (Fa(0.5-71)). However, more importantly, we find that the olivines make up two compositionally distinct populations (Fa(0.5-5) and Fa(21-71)). Grains from both populations are found within an extremely close proximity and we see no obvious evidence of two distinct lithologies within our samples. Therefore, we conclude that the olivine grains found in the ALHA77307 matrix must have crystallized within two unique formation conditions and were later mixed at a very fine scale during the accretion epoch. Here, we propose a possible explanation based on Cr and Mn concentrations in the olivine.

  19. Optimization of the thermoelectric figure of merit of fine-grained semiconductor materials based upon lead telluride

    NASA Astrophysics Data System (ADS)

    Rowe, D. M.

    1986-02-01

    Lead telluride type semiconductors are used in the fabrication of thermoelectric modules. This report covers the programme to produce materials based upon lead telluride with improved figures of merit and hence greater thermoelectric conversion efficiency. One way of improving the figure of merit is by reducing the lattice thermal conductivity of the material. This can be achieved by increasing phonon grain boundary scattering. A realistic theoretical model has been developed for lead telluride and used to investigate the lattice thermal conductivity as a function of grain size and level of doping. In optimally doped material with a grain size of 1 micrometer, the reduction in lattice thermal conductivity was predicted to be 4-6 percent compared with equivalent single crystal. Thermal diffusivity measurements on small grained compacts supported this prediction. Phonon grain boundary scattering is enhanced in semiconductor alloys because of the presence of disorder scattering and the theoretical model was extended to take this factor into account. PbSnTe and PbGeTe were identified as alloys whose lattice thermal conductivity could be significantly decreased by a reduction in grain size and in optimally doped compacted material with a grain size of 0.5 micrometer the reduction compared to equivalent single crystal material was estimated to be 11 and 14 percent respectively.

  20. Determination of mineralogy and grain size of the magnetic fraction from outdoor and indoor urban dust from several Bulgarian cities

    NASA Astrophysics Data System (ADS)

    Petrov, Petar; Jordanova, Neli; Jordanova, Diana

    2014-05-01

    Dust is the most important factor determining urban air quality. The identification of magnetic minerals, carriers of magnetic signal of dust samples, is important for a correct interpretation of concentration, domain state and grain-size indicative parameters. The aim of the present study is to characterize magnetically indoor and outdoor dusts from six big cities in Bulgaria and to link them to degree of pollution of the environment. The aim is also to propose the most effective methods for characterization: thermomagnetic analysis of magnetic susceptibility, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM), hysteresis loops. Dust material was collected monthly during the period May 2009- November 2010. The main magnetic mineral in outdoor and indoor dust, identified by thermomagnetic analysis of magnetic susceptibility, is magnetite (Fe3O4). The dominant role of magnetite in determination of magnetic signal of the studied dusts allows the use of hysteresis parameters as proxies for the effective magnetic grain size of ferrimagnetic grains. The calculated ratios Mrs/Ms and Bcr/Bc vary in the intervals (0.055 - 0.1) and (3.08 - 5.14), respectively. The coercivity of magnetic fraction in indoor dust is lower compared to that of outdoor dust. This dependence probably shows that the main source of dust is the outside pollution with PM10. Higher values typical for outdoor dust in comparison with respective sample from indoor dust show that quantity of the paramagnetic minerals is higher in outdoor dust. Probable source of such particles is dust from erosion of soils in the area.

  1. Erosion characteristics of fine-grained, beach-building sediment along the Colorado River in Grand Canyon

    NASA Astrophysics Data System (ADS)

    Akahori, R.; Schmeeckle, M. W.; Topping, D. J.

    2004-12-01

    In the Grand Canyon segment of the Colorado River, eddy sandbars, which form in lateral recirculation eddies, are important for endangered fish habitat, riparian habitat, protection of archeological sites, and recreation. By virtue of the 1963 closure of Glen Canyon Dam, sediment (i.e., sand, silt, and clay) supply to the Colorado River at the upstream boundary of Grand Canyon National Park has been reduced to about 5% of the pre-dam supply. This has caused substantial reduction in the size of eddy sandbars. The major supplier of sediment in the first 123 km downstream from Glen Canyon Dam is the Paria River, and its sediment consists mainly of clay, silt, and finer sand. During large floods on the Paria River, about 50% of the load is silt and clay, and the median size of the sand is about 0.11-0.12 mm. In order to restore the eroded eddy sandbars in the upper portion of Grand Canyon, an experimental controlled flood, i.e., Beach Habitat Building Flow (BHBF), has been proposed following enrichment of the sediment supply by flooding on the Paria River. Deposits produced by this BHBF should be fine-grained and cohesive. Understanding the sediment-transport behavior of this cohesive sediment is essential for the prediction and evaluation of the influence of the BHBF on rebuilding bars and increasing turbidity in the main channel. In this study, cohesive sediment samples of beach bars were collected from bars in the Colorado River in the Lake Mead delta. Laboratory experiments have tested the bulk density, erosion rate, and critical shear stress of these collected samples. The erosion rate of each sample was tested several times at different boundary shear stresses in a laboratory flume, allowing for estimation of the critical shear stress. Samples were placed in a 10-cm diameter cylinder below the flume. The sample was pushed out of the cylinder as it was eroded, such that the sample surface remained at the same height as the flume floor. Boundary shear stresses were

  2. Estimating concentrations of fine-grained and total suspended sediment from close-range remote sensing imagery

    USGS Publications Warehouse

    Mosbrucker, Adam; Spicer, Kurt R.; Christianson, Tami; Uhrich, Mark A.

    2015-01-01

    data range among sensors. Of greatest interest to many programs is a hysteresis in the relationship between turbidity and SSC, attributed to temporal variation of particle size distribution (Landers and Sturm, 2013; Uhrich et al., 2014). This phenomenon causes increased uncertainty in regression-estimated values of SSC, due to changes in nephelometric reflectance off the varying grain sizes in suspension (Uhrich et al., 2014). Here, we assess the feasibility and application of close-range remote sensing to quantify SSC and particle size distribution of a disturbed, and highly-turbid, river system. We use a consumer-grade digital camera to acquire imagery of the river surface and a depth-integrating sampler to collect concurrent suspended-sediment samples. We then develop two empirical linear regression models to relate image spectral information to concentrations of fine sediment (clay to silt) and total suspended sediment. Before presenting our regression model development, we briefly summarize each data-acquisition method.

  3. Krypton and xenon in lunar fines

    NASA Technical Reports Server (NTRS)

    Basford, J. R.; Dragon, J. C.; Pepin, R. O.; Coscio, M. R., Jr.; Murthy, V. R.

    1973-01-01

    Data from grain-size separates, stepwise-heated fractions, and bulk analyses of 20 samples of fines and breccias from five lunar sites are used to define three-isotope and ordinate intercept correlations in an attempt to resolve the lunar heavy rare gas system in a statistically valid approach. Tables of concentrations and isotope compositions are given.

  4. Carbon Isotopic Fractionation During Formation of Macromolecular Organic Grain Coatings via FTT Reactions

    NASA Technical Reports Server (NTRS)

    Nuth, J. A.; Johnson, N. M.; Elsila-Cook, J.; Kopstein, M.

    2011-01-01

    Observations of carbon isotopic fractionation of various organic compounds found in meteorites may provide useful diagnostic information concerning the environments and mechanisms that were responsible for their formation. Unfortunately, carbon has only two stable isotopes, making interpretation of such observations quite problematic. Chemical reactions can increase or decrease the C-13/C-12 ratio by various amounts, but the final ratio will depend on the total reaction pathway followed from the source carbon to the final product, a path not readily discernable after 4.5 billion years. In 1970 Libby showed that the C-13/C-12 ratios of terrestrial and meteoritic carbon were similar by comparing carbon from the Murchison meteorite to that of terrestrial sediments. More recent studies have shown that the C-13/C-12 ratio of the Earth and meteorites may be considerably enriched in C-13 compared to the ratio observed in the solar wind [2], possibly suggesting that carbon produced via ion-molecule reactions in cold dark clouds could be an important source of terrestrial and meteoritic carbon. However, meteoritic carbon has been subjected to parent body processing that could have resulted in significant changes to the C-13/C-12 ratio originally present while significant variation has been observed in the C-13/C-12 ratio of the same molecule extracted from different terrestrial sources. Again we must conclude that understanding the ratio found in meteorites may be difficult.

  5. High temperature anelastic and viscoplastic deformation of fine-grained MgO-doped Al{sub 2}O{sub 3}

    SciTech Connect

    Lakki, A.; Schaller, R.; Benoit, W.; Carry, C.

    1998-01-05

    Mechanical loss and dynamic shear modulus measurements at high temperature (1,200--1,550 K) were performed on fine-grained (0.8 {micro}m) MgO-doped alumina in the low frequency range (10{sup {minus}4}--10 Hz), by using a differential inverted torsion pendulum working with forced vibrations. Anelastic and viscoplastic relaxation phenomena were observed, characterized by an activation enthalpy of 840 kJ/mol. These appear as a mechanical loss peak and a viscoplastic damping background. Moreover, a stress-dependent component, activated above a threshold-stress amplitude of 2--4 MPa was found. The mechanical loss spectrum was analyzed using classical and modified approaches and the possible mechanisms discussed in terms of a simple model invoking grain boundary dislocations.

  6. High temperature plastic deformation at very low stresses of fine-grained Y{sub 2}O{sub 3}-partially stabilized ZrO{sub 2}

    SciTech Connect

    Bravo-Leon, A.; Jimenez-Melendo, M.; Dominguez-Rodriguez, A.

    1996-08-15

    Plastic deformation at elevated temperatures (1300--1450C) of 3 and 4 mol% Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} polycrystals with fine grain size (d < 1 {micro}m) has been studied at very low stresses (<10 MPa). Extensive internal cavitation has been found for a few percent of strain, instead of the superplastic behavior exhibited by these materials at intermediate and high stresses, along with a change of the stress exponent. These features are explained on the basis of a gradual inhibition of the grain boundary sliding to accommodate the macroscopic strain when decreasing the stress, supporting the existence of a threshold stress for this mechanism.

  7. Vertical distribution of heavy metals in grain size fractions in sedimentary rocks: Mosina-Krajkowo water well field, Poland.

    PubMed

    Frankowski, M; Siepak, M; Zioła, A; Novotný, K; Vaculovic, T; Siepak, J

    2009-08-01

    The paper presents the results of heavy metals determination in samples of sedimentary rocks from the Mosina-Krajkowo water well field (Poland). The concentration of heavy metals was analysed by type of rock (sand, gravel, warp, silt, till, and clay). Variation of heavy metal concentrations with depth was studied taking into account the age series of the rocks (fluvial sediments of the modern Warta River valley, sediments of the Baltic Glaciation, tills of the Middle-Polish Glaciation, sediments of the Masovian Interglacial (Holstein), tills of the Poznań series) and granulometric fractions. The grain sizes considered included: >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.25, 0.25-0.1, 0.1-0.063, and <0.063 mm. The concentrations of the heavy metals studied were found to change with the type of rock, age series, and granulometric fraction. The levels of the metals were determined by the technique of atomic absorption spectrometry with flame atomisation (F-AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES).

  8. Characterization of the fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge generated by the stainless steelmaking industry.

    PubMed

    Majuste, Daniel; Mansur, Marcelo Borges

    2008-05-01

    The argon oxygen decarburization with lance (AOD-L) sludge generated by the stainless steelmaking industry is a hazardous waste due to the presence of chromium. While its coarse fraction is usually recycled into the own industrial process, the fine fraction is normally disposed in landfills. Techniques such as briquetting or magnetic separation were found to be inadequate to treat it for reuse purposes. So, in this work, the fine fraction of the AOD-L sludge was characterized aiming to find alternative methods to treat it. This sludge consists of a fine powder (mean diameter of 1 microm) containing 34 +/- 2% (w/w) of iron, 10.2 +/- 0.9% (w/w) of chromium and 1.4 +/- 0.1% (w/w) of nickel. The main crystalline phases identified in this study were chromite (FeCr(2)O(4)), magnetite (Fe(3)O(4)), hematite (Fe(2)O(3)) and calcite (CaCO(3)). In the digestion tests, the addition of HClO(4) has favored the dissolution of chromite which is a very stable oxide in aqueous media. Nickel was found in very fine particles, probably in the metallic form or associated with iron and oxygen. The sludge was classified as hazardous waste, so its disposal in landfills should be avoided.

  9. Prospects for Improving the Critical Current Density of Superconducting Nb3Sn Strands via Optimization of Nb3Sn Fraction, Stoichiometry, and Grain Size

    NASA Astrophysics Data System (ADS)

    Xu, Xingchen

    determined by three factors: the fraction of current-carrying Nb3Sn phase in a subelement, the irreversibility field Birr which mainly depends on the Nb3Sn phase composition (i.e., Sn content), doping, and strain state, and the flux-line pinning characteristics (including the maximum pinning force Fp,max and the pinning force peak field) which mainly depend on grain size. Then these three factors will be addressed in three chapters. In chapter 3, the question "how to improve Nb 3Sn fraction in a subelement" is investigated. A model is developed to predict the phase fractions in reacted strands based on the starting amounts of precursors. In chapter 4, a model is developed to find out what essentially determines the composition of non-stoichiometric compounds formed by diffusion reactions. It can be used as a guide for controlling the Sn content of the Nb3Sn phase formed in Sn source/Nb3Sn/Nb diffusion reaction couples. Finally, chapter 5 demonstrates that the subelement structures can be carefully modified to enable the internal oxidation of Nb-Zr alloy, so that fine ZrO2 precipitates are formed in Nb3Sn; these ZrO2 particles can significantly refine Nb3Sn grain size and improve the high-field Jc.

  10. What does the fine-scale petrography of IDPs reveal about grain formation and evolution in the early solar system?

    NASA Technical Reports Server (NTRS)

    Bradley, John

    1994-01-01

    The 'pyroxene' interplanetary dust particles (IDP's) may be the best samples for investigation of primordial grain-forming reactions because they appear to have experienced negligible post-accretional alteration. They are likely to continue to yield information about gas-to-solid condensation and other grain-forming reactions that may have occurred either in the solar nebular or presolar interstellar environments. An immediate challenge lies in understanding the nanometer-scale petrography of the ultrafine-grained aggregates in 'pyroxene' IDP's. Whether these aggregates contain components from diverse grain-forming environments may ultimately be answered by systematic petrographic studies using electron microscopes capable of high spatial resolution microanalysis. It may be more difficult to decipher evidence of grain formation and evolution in 'olivine' and 'layer silicate' IDP's because they appear to have experienced post-accretional alteration. Most of the studied 'olivine' IDPs have been subjected to heating and equilibration, perhaps during atmospheric entry, while the 'layer silicate' IDP's have experienced aqueous alteration.

  11. Tree cover at fine and coarse spatial grains interacts with shade tolerance to shape plant species distributions across the Alps

    PubMed Central

    Nieto-Lugilde, Diego; Lenoir, Jonathan; Abdulhak, Sylvain; Aeschimann, David; Dullinger, Stefan; Gégout, Jean-Claude; Guisan, Antoine; Pauli, Harald; Renaud, Julien; Theurillat, Jean-Paul; Thuiller, Wilfried; Van Es, Jérémie; Vittoz, Pascal; Willner, Wolfgang; Wohlgemuth, Thomas; Zimmermann, Niklaus E.; Svenning, Jens-Christian

    2015-01-01

    The role of competition for light among plants has long been recognised at local scales, but its importance for plant species distributions at larger spatial scales has generally been ignored. Tree cover modifies the local abiotic conditions below the canopy, notably by reducing light availability, and thus, also the performance of species that are not adapted to low-light conditions. However, this local effect may propagate to coarser spatial grains, by affecting colonisation probabilities and local extinction risks of herbs and shrubs. To assess the effect of tree cover at both the plot- and landscape-grain sizes (approximately 10-m and 1-km), we fit Generalised Linear Models (GLMs) for the plot-level distributions of 960 species of herbs and shrubs using 6,935 vegetation plots across the European Alps. We ran four models with different combinations of variables (climate, soil and tree cover) at both spatial grains for each species. We used partial regressions to evaluate the independent effects of plot- and landscape-grain tree cover on plot-level plant communities. Finally, the effects on species-specific elevational range limits were assessed by simulating a removal experiment comparing the species distributions under high and low tree cover. Accounting for tree cover improved the model performance, with the probability of the presence of shade-tolerant species increasing with increasing tree cover, whereas shade-intolerant species showed the opposite pattern. The tree cover effect occurred consistently at both the plot and landscape spatial grains, albeit most strongly at the former. Importantly, tree cover at the two grain sizes had partially independent effects on plot-level plant communities. With high tree cover, shade-intolerant species exhibited narrower elevational ranges than with low tree cover whereas shade-tolerant species showed wider elevational ranges at both limits. These findings suggest that forecasts of climate-related range shifts for herb

  12. The respective effects of soil heavy metal fractions by sequential extraction procedure and soil properties on the accumulation of heavy metals in rice grains and brassicas.

    PubMed

    Xiao, Ling; Guan, Dongsheng; Peart, M R; Chen, Yujuan; Li, Qiqi

    2017-01-01

    This study was carried out to examine heavy metal accumulation in rice grains and brassicas and to identify the different controls, such as soil properties and soil heavy metal fractions obtained by the Community Bureau of Reference (BCR) sequential extraction, in their accumulation. In Guangdong Province, South China, rice grain and brassica samples, along with their rhizospheric soil, were collected from fields on the basis of distance downstream from electroplating factories, whose wastewater was used for irrigation. The results showed that long-term irrigation using the electroplating effluent has not only enriched the rhizospheric soil with Cd, Cr, Cu, and Zn but has also increased their mobility and bioavailability. The average concentrations of Cd and Cr in rice grains and brassicas from closest to the electroplating factories were significantly higher than those from the control areas. Results from hybrid redundancy analysis (hRDA) and redundancy analysis (RDA) showed that the BCR fractions of soil heavy metals could explain 29.0 and 46.5 % of total eigenvalue for heavy metal concentrations in rice grains and brassicas, respectively, while soil properties could only explain 11.1 and 33.4 %, respectively. This indicated that heavy metal fractions exerted more control upon their concentrations in rice grains and brassicas than soil properties. In terms of metal interaction, an increase of residual Zn in paddy soil or a decrease of acid soluble Cd in the brassica soil could enhance the accumulation of Cd, Cu, Cr, and Pb in both rice grains and brassicas, respectively, while the reducible or oxidizable Cd in soil could enhance the plants' accumulation of Cr and Pb. The RDA showed an inhibition effect of sand content and CFO on the accumulation of heavy metals in rice grains and brassicas. Moreover, multiple stepwise linear regression could offer prediction for Cd, Cu, Cr, and Zn concentrations in the two crops by soil heavy metal fractions and soil properties.

  13. Processing and properties of high-purity, fine-grain-size depleted-uranium, deep-drawn shapes

    SciTech Connect

    Jackson, R J; Lundberg, M R; Bruchey, W L

    1980-10-01

    Unalloyed uranium is a candidate material for shaped charge liners used in conventional ordinance applications. For test purposes, it was decided that a high-grade uranium material with good toughness should be used. This report describes a process for producing a high-purity (less than 500 ppM total impurities) wrought material consisting of a recrystallized, equiaxed grain structure with a 10 micron (ASTM-8) average grain size. The fabrication process is discussed in detail. In all, six material conditions having a wide range of mechanical and structural properties were investigated. The tensile, hardness, and microstructural properties of these six material conditions are reported in detail.

  14. Effects of salinity and particle concentration on sediment hydrodynamics and critical bed-shear-stress for erosion of fine grained sediments used in wetland restoration projects

    NASA Astrophysics Data System (ADS)

    Ghose-Hajra, M.; McCorquodale, A.; Mattson, G.; Jerolleman, D.; Filostrat, J.

    2015-03-01

    Sea-level rise, the increasing number and intensity of storms, oil and groundwater extraction, and coastal land subsidence are putting people and property at risk along Louisiana's coast, with major implications for human safety and economic health of coastal areas. A major goal towards re-establishing a healthy and sustainable coastal ecosystem has been to rebuild Louisiana's disappearing wetlands with fine grained sediments that are dredged or diverted from nearby rivers, channels and lakes to build land in open water areas. A thorough geo-hydrodynamic characterization of the deposited sediments is important in the correct design and a more realistic outcome assessment of the long-term performance measures for ongoing coastal restoration projects. This paper evaluates the effects of salinity and solid particle concentration on the re-suspension characteristics of fine-grained dredged sediments obtained from multiple geographic locations along the Gulf coast. The critical bed-shear-stress for erosion has been evaluated as a function of sedimentation time. The sediment hydrodynamic properties obtained from the laboratory testing were used in a numerical coastal sediment distribution model to aid in evaluating sediment diversions from the Mississippi River into Breton Sound and Barataria Bay.

  15. Toxicological investigations on the respirable fraction of silicon carbide grain products by the in vitro vector model.

    PubMed

    Bruch, Joachim; Rehn, Bernd; Duval-Arnould, Guy; Efskind, John; Röderer, Gerhard; Sébastian, Patrick

    2014-04-01

    Increased lung cancer incidence with workers at the production site of crude silicon carbide (SiC) using the Acheson process has been reported. Several agents derived from the process were discussed as causative factors. Recently concern had been expressed about the presence of cleavage fragments (CFs) in commercial products fulfilling the WHO criteria for fibers. This study has focused on the toxicological significance of such CFs. The test samples were respirable fractions of five different commercial samples of SiC grains. The CF content (scanning electron microscopy) was in the range 17-493 fibers/µg. Crystalline silica and whiskers could not be detected. Quartz DQ12, cristobalite, SiC whisker, UICC crocidolite and electrocorundum were used as control reference samples. Biological activity was assessed with the in vitro vector model (VM) on ex vivo rat and guinea pig alveolar macrophages (AMs). The dose range of the VM is derived from calculated AM loads from intratracheal instillation experiments and confirmed by measured AM loads from inhalation studies on alumina monohydrate particles with low biological activity: ≤120 pg/AM. The response of the references was clearly different from that of the SiC grains which yielded low toxicity overall. However, the parameter reactive oxygen species secreted by AMs was elevated at the higher SiC doses, but not related to the CF content of these samples. Our data showed that CFs seem to have no biological relevance. This is in agreement with results from recent studies in which no carcinogenic activity had been demonstrated for CFs.

  16. The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust.

    PubMed

    Zhang, Haibo; Luo, Yongming; Makino, Tomoyuki; Wu, Longhua; Nanzyo, Masami

    2013-03-15

    The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessibility of the metals as well as the mobility of the fine particles in soil.

  17. Periodic Viscous Shear Heating Instability in Fine-Grained Shear Zones: Possible Mechanism for Intermediate Depth Earthquakes and Slow Earthquakes?

    NASA Astrophysics Data System (ADS)

    Kelemen, P. B.; Hirth, G.

    2004-12-01

    Localized ductile shear zones with widths of cm to m are observed in exposures of Earth's shallow mantle (e.g., Kelemen & Dick JGR 95; Vissers et al. Tectonophys 95) and dredged from oceanic fracture zones (e.g., Jaroslow et al. Tectonophys 96). These are mylonitic (grain size 10 to 100 microns) and record mineral cooling temperatures from 1100 to 600 C. Pseudotachylites in a mantle shear zone show that shear heating temperatures can exceed the mantle solidus (e.g., Obata & Karato Tectonophys 95). Simple shear, recrystallization, and grain boundary sliding all decrease the spacing between pyroxenes, so olivine grain growth at lower stress is inhibited; thus, once formed, these shear zones do not "heal" on geological time scales. Reasoning that grain-size sensitive creep will be localized within these shear zones, rather than host rocks (grain size 1 to 10 mm), and inspired by the work of Whitehead & Gans (GJRAS 74), we thought these might undergo repeated shear heating instabilities. In this view, as elastic stress increases, the shear zone weakens via shear heating; rapid deformation of the weak shear zone releases most stored elastic stress; lower stress and strain rate coupled with diffusion of heat into host rocks leads to cooling and strengthening, after which the cycle repeats. We constructed a simple numerical model incorporating olivine flow laws for dislocation creep, diffusion creep, grain boundary sliding, and low T plasticity. We assumed that viscous deformation remains localized in shear zones, surrounded by host rocks undergoing elastic deformation. We fixed the velocity along one side of an elastic half space, and calculated stress due to elastic strain. This stress drives viscous deformation in a shear zone of specified width. Shear heating and thermal diffusion control temperature evolution in the shear zone and host rocks. A maximum of 1400 C (where substantial melting of peridotite would occur) is imposed. Grain size evolves during dislocation

  18. High hardness BaCb-(BxOy/BN) composites with 3D mesh-like fine grain-boundary structure by reactive spark plasma sintering.

    PubMed

    Vasylkiv, Oleg; Borodianska, Hanna; Badica, Petre; Grasso, Salvatore; Sakka, Yoshio; Tok, Alfred; Su, Liap Tat; Bosman, Michael; Ma, Jan

    2012-02-01

    Boron carbide B4C powders were subject to reactive spark plasma sintering (also known as field assisted sintering, pulsed current sintering or plasma assisted sintering) under nitrogen atmosphere. For an optimum hexagonal BN (h-BN) content estimated from X-ray diffraction measurements at approximately 0.4 wt%, the as-prepared BaCb-(BxOy/BN) ceramic shows values of Berkovich and Vickers hardness of 56.7 +/- 3.1 GPa and 39.3 +/- 7.6 GPa, respectively. These values are higher than for the vacuum SPS processed B4C pristine sample and the h-BN -mechanically-added samples. XRD and electronic microscopy data suggest that in the samples produced by reactive SPS in N2 atmosphere, and containing an estimated amount of 0.3-1.5% h-BN, the crystallite size of the boron carbide grains is decreasing with the increasing amount of N2, while for the newly formed lamellar h-BN the crystallite size is almost constant (approximately 30-50 nm). BN is located at the grain boundaries between the boron carbide grains and it is wrapped and intercalated by a thin layer of boron oxide. BxOy/BN forms a fine and continuous 3D mesh-like structure that is a possible reason for good mechanical properties.

  19. Methane production from the soluble fraction of distillers' dried grains with solubles in anaerobic sequencing batch reactors.

    PubMed

    Cassidy, D P; Hirl, P J; Belia, E

    2008-06-01

    Methane production from the soluble fraction of distillers' dried grains with solubles, a co-product of ethanol production, was studied in 2-L anaerobic sequencing batch reactors (ASBRs) under 10 different operating conditions. Methane production and chemical oxygen demand (COD) removal were quantified for a wide range of operating parameters. Chemical oxygen demand removals of 64 to 95% were achieved at organic loading rates ranging from 1.5 to 22.2 g COD/L x d, solids retention times from 8 to 40 days, and food-to-microorganism ratios ranging from 0.4 to 1.9 g COD/g volatile suspended solids (VSS) x d. Biogas methane content varied from 61 to 74%, with 0.29 L CH4 produced/g COD removed. Roughly 56% of the influent COD and 84% of the COD removed in the ASBRs was converted to methane. Microbial yield (Y) and decay (b) constants were determined to be Y = 0.126 g VSS/g COD removed and b = 0.032 day(-1), respectively. Methane produced from co-products can reduce the costs and fossil-fuel consumption of ethanol manufacture.

  20. Mineralogy of fine-grained alluvium from borehole U11g, expl. 1, northern Frenchman Flat area, Nevada Test Site

    USGS Publications Warehouse

    Jones, B.F.

    1982-01-01

    The mineralogy of matrix fines in alluvium from borehole Ullg, expl. 1, north of Frenchman Flat, Nevada Test Site, has been examined for evidence of past variations in water table elevation. Although greater abundance of zeolite and slightly more expanded basal spacings in smectite clays suggest effects of increased hydration of material up to 50 m above the present water table, these differences might also be related to provenance of environment of deposition. The relative uniformity of clay hydration properties in the 50 meters above the current water table suggest long-term stability near the present level. (USGS)

  1. Mechanical response and microcrack formation in a fine-grained duplex TiAl at different strain rates and temperatures

    SciTech Connect

    Jin, Z.; Cady, C.; Gray, G.T. III; Kim, Y.-W.

    1996-10-01

    Compressive behavior of this alloy was studied at strain rates of 0. 001 and 2000 sec{sup -1} and temperatures from -196 C to 1200 C. Temperature dependence of yield stress was found to depend on strain rate: At the quasi-static strain rate, 0.001 sec{sup -1}, the yield stress decreases with temperature with a plateau between 200 and 800 C. At the high strain rate, 2000 sec{sup -1}, the yield stress exhibits a positive temperature dependence above 600 C. Strain hardening rate decreases dramatically with temperature in the very low and high temperature regions with a plateau at intermediate temperatures for both strain rates. As the strain rate increases, the strain hardening rate plateaus extended to higher temperatures. The strain rate sensitivity increases slightly with temperature (but less than 0.1) for strain rates above 0.001 sec{sup -1}. However, at a strain rate of 0.001 sec{sup -1}, there is a dramatic increase in the strain rate sensitivity with temperature; above 1100 C, the rate sensitivity becomes much larger. Microcracks occurring in grain interiors and at grain boundaries were observed at all strain rates and temperatures. Formation and distribution of microcracks were found to vary depending on strain rate and deformation temperature.

  2. Nearly full-dense and fine-grained AZO:Y ceramics sintered from the corresponding nanoparticles

    PubMed Central

    2012-01-01

    Aluminum-doped zinc oxide ceramics with yttria doping (AZO:Y) ranging from 0 to 0.2 wt.% were fabricated by pressureless sintering yttria-modified nanoparticles in air at 1,300°C. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, a physical property measurement system, and a densimeter were employed to characterize the precursor nanoparticles and the sintered AZO ceramics. It was shown that a small amount of yttria doping can remarkably retard the growth of the as-received precursor nanoparticles, further improve the microstructure, refine the grain size, and enhance the density for the sintered ceramic. Increasing the yttria doping to 0.2 wt.%, the AZO:Y nanoparticles synthetized by a coprecipitation process have a nearly sphere-shaped morphology and a mean particle diameter of 15.1 nm. Using the same amount of yttria, a fully dense AZO ceramic (99.98% of theoretical density) with a grain size of 2.2 μm and a bulk resistivity of 4.6 × 10−3 Ω·cm can be achieved. This kind of AZO:Y ceramic has a potential to be used as a high-quality sputtering target to deposit ZnO-based transparent conductive films with better optical and electrical properties. PMID:22929049

  3. Nearly full-dense and fine-grained AZO:Y ceramics sintered from the corresponding nanoparticles.

    PubMed

    Yang, Ye; Lan, Pinjun; Wang, Muqin; Wei, Tiefeng; Tan, Ruiqin; Song, Weijie

    2012-08-29

    Aluminum-doped zinc oxide ceramics with yttria doping (AZO:Y) ranging from 0 to 0.2 wt.% were fabricated by pressureless sintering yttria-modified nanoparticles in air at 1,300°C. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, a physical property measurement system, and a densimeter were employed to characterize the precursor nanoparticles and the sintered AZO ceramics. It was shown that a small amount of yttria doping can remarkably retard the growth of the as-received precursor nanoparticles, further improve the microstructure, refine the grain size, and enhance the density for the sintered ceramic. Increasing the yttria doping to 0.2 wt.%, the AZO:Y nanoparticles synthetized by a coprecipitation process have a nearly sphere-shaped morphology and a mean particle diameter of 15.1 nm. Using the same amount of yttria, a fully dense AZO ceramic (99.98% of theoretical density) with a grain size of 2.2 μm and a bulk resistivity of 4.6 × 10-3 Ω·cm can be achieved. This kind of AZO:Y ceramic has a potential to be used as a high-quality sputtering target to deposit ZnO-based transparent conductive films with better optical and electrical properties.

  4. Upwelling-driven reworking of a MTD's fine-grained plume: an example at the Cariaco Basin/Cariaco Gulf connection.

    NASA Astrophysics Data System (ADS)

    Aguilar, Iliana; Beck, Christian; Audemard, Franck; Crouzet, Christian; Sabatier, Pierre; Develle, Anne-Lise; Boussafir, Mohammed; Campos, Corina

    2016-04-01

    The Cariaco Basin is a 1400 m-deep and 90 km-wide pull-apart basin, in the south-eastern corner of the Caribbean Sea. To the East, it is connected to the Cariaco Gulf, a 60 km-long, 15 km-wide, and 90 m-deep appendix. Both are E-W elongated and developed upon the south-eastern transform boundary of the Caribbean Plate, an active limit here mainly represented by the El Pilar Fault. The Gulf of Cariaco entrance is a 55 m-deep, and 5 km-wide sill mainly controlled by the large Manzanares River delta, which western foreset slope is facing the Basin's eastern edge. Within this connection area, two particular sedimentary processes have been previously documented: 1) strong seasonal upwelling responsible for the transfer of deep particulate organic matter from the Basin into the Gulf; 2) the recent occurrence, in the Basin, of a fine-grained suspension related to a submarine landslide; this event was detected after the 1997 Cariaco earthquake (Thunell et al., 1999; Lorenzoni et al., 2012) and was related to a slope failure of the Manzanares delta western foreset. From short gravity cores retrieved in the Gulf, we analysed the last millennium of sedimentation (components, transport and settling processes) using classical proxies and physical properties. All parameters led to underline: - a permanent mixed provenance of particulate Organic Matter in the main part of the Gulf: i) in situ and ii) allochtonous; - the occurrence of coarse siliciclastic layers related to flooding from the southern edge of the Gulf; - the occurrence of one peculiar fine-grained siliciclastic layer with a widespread distribution, dated around 1850 AD; - an abrupt increase of open marine influence just after the above-mentioned layer. Concerning the "background" permanent sedimentation, these results confirm the importance of upwelling through the connection between the Gulf and the Basin (transfer of the "allochtonous" O.M.). For the fine-grained silicilastic "event", we could discard a

  5. Thermoelectric properties of fine-grained FeVSb half-Heusler alloys tuned to p-type by substituting vanadium with titanium

    SciTech Connect

    Zou, Minmin; Li, Jing-Feng; Kita, Takuji

    2013-02-15

    Fine-grained Ti-doped FeVSb half-Heusler alloys were synthesized by combining mechanical alloying and spark plasma sintering and their thermoelectric properties were investigated with an emphasis on the influences of Ti doping and phase purity. It was found that substituting V with Ti can change the electrical transport behavior from n-type to p-type due to one less valence electron of Ti than V, and the sample with nominal composition FeV{sub 0.8}Ti{sub 0.4}Sb exhibits the largest Seebeck coefficient and the maximum power factor. By optimizing the sintering temperature and applying annealing treatment, the power factor is significantly improved and the thermal conductivity is reduced simultaneously, resulting in a ZT value of 0.43 at 500 Degree-Sign C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements. - Graphical abstract: Fine-grained Ti-doped FeVSb alloys were prepared by the MA-SPS method. The maximum ZT value reaches 0.43 at 500 Degree-Sign C, which is relatively high for p-type half-Heusler alloys. Highlights: Black-Right-Pointing-Pointer Ti-doped FeVSb half-Heusler alloys were synthesized by combining MA and SPS. Black-Right-Pointing-Pointer Substituting V with Ti changes the electrical behavior from n-type to p-type. Black-Right-Pointing-Pointer Thermoelectric properties are improved by optimizing sintering temperature. Black-Right-Pointing-Pointer Thermoelectric properties are further improved by applying annealing treatment. Black-Right-Pointing-Pointer A high ZT value of 0.43 is obtained at 500 Degree-Sign C for p-type Ti-doped FeVSb alloys.

  6. The impact of disposal of fine-grained sediments from maintenance dredging works on SPM concentration and fluid mud in and outside the harbor of Zeebrugge

    NASA Astrophysics Data System (ADS)

    Fettweis, Michael; Baeye, Matthias; Cardoso, Claudio; Dujardin, Arvid; Lauwaert, Brigitte; Van den Eynde, Dries; Van Hoestenberghe, Thomas; Vanlede, Joris; Van Poucke, Luc; Velez, Carlos; Martens, Chantal

    2016-11-01

    The amount of sediments to be dredged and disposed depends to a large part on the suspended particulate matter (SPM) concentration. Tidal, meteorological, climatological, and seasonal forcings have an influence on the horizontal and vertical distribution of the SPM in the water column and on the bed and control the inflow of fine-grained sediments towards harbors and navigation channels. About 3 million tons (dry matter) per year of mainly fine-grained sediments is dredged in the port of Zeebrugge and is disposed on a nearby disposal site. The disposed sediments are quickly resuspended and transported away from the site. The hypothesis is that a significant part of the disposed sediments recirculates back to the dredging places and that a relocation of the disposal site to another location at equal distance to the dredging area would reduce this recirculation. In order to validate the hypothesis, a 1-year field study was set up in 2013-2014. During 1 month, the dredged material was disposed at a new site. Variations in SPM concentration were related to tides, storms, seasonal changes, and human impacts. In the high-turbidity Belgian near-shore area, the natural forcings are responsible for the major variability in the SPM concentration signal, while disposal has only a smaller influence. The conclusion from the measurements is that the SPM concentration decreases after relocation of the disposal site but indicate stronger (first half of field experiment) or weaker (second half of field experiment) effects that are, however, supported by the environmental conditions. The results of the field study may have consequences on the management of disposal operations as the effectiveness of the disposal site depends on environmental conditions, which are inherently associated with chaotic behavior.

  7. The Smallest Lunar Grains: Analytical TEM Characterization of the Sub-micron Size Fraction of a Mare Soil

    NASA Technical Reports Server (NTRS)

    Thompson, M.; Christoffersen, R.

    2010-01-01

    The chemical composition, mineralogical type, and morphology of lunar regolith grains changes considerably with decreasing size, and below the approx.25 m size range the correlation between these parameters and remotely-sensed lunar surface properties connected to space weathering increases significantly. Although trends for these parameters across grain size intervals greater than 20 m are now well established, the 0 to 20 m size interval remains relatively un-subdivided with respect to variations in grain modal composition, chemistry and microstructure. Of particular interest in this size range are grains in the approximate < 1 m diameter class, whose fundamental properties are now the focus of lunar research pertaining to electrostatic grain transport, dusty plasmas, and lunar dust effects on crew health and exploration systems. In this study we have used analytical transmission electron microscopy (TEM) to characterize the mineralogy, microstructure and major element composition of grains below the 1 m size threshold in lunar soil 10084.

  8. Mineralogy and Textural Characteristics of Fine-grained Rims in the Yamato 791198 CM2 Carbonaceous Chondrite: Constraints on the Location of Aqueous Alteration

    NASA Technical Reports Server (NTRS)

    Chizmadia, Lysa J.; Brearley, Adrian J.

    2003-01-01

    Carbonaceous chondrites provide important clues into the nature of physical and chemical processes in the early solar system. A question of key importance concerns the role of water in solar nebular and asteroidal processes. The effects of water on primary mineral assemblages have been widely recognized in chondritic meteorites, especially the CI and CM carbonaceous chondrites. These meteorites have undergone extensive aqueous alteration that occurred prior to their arrival on Earth. In the case of the CM chondrites, this alteration has resulted in the partial to complete replacement of the primary nebular phases with secondary alteration phases. Considerable controversy exists as to the exact location where the alteration of the CM chondrites occurred. Several textural lines of evidence have been cited in support of aqueous alteration prior to the accretion of the final parent asteroid. An important line of evidence to support this hypothesis is the dis-equilibrium nature of fine-grained rims and matrix materials. [2] also noted the juxtaposition of micron-sized Fe-Ni metal grains and apparently unaltered chondrule glass against hydrated rim silicates. Conversely, there is a large body of evidence in favor of parent body alteration such as the occurrence of undisturbed Fe-rich aureoles and the systematic redistribution of elemental components over millimeters, e.g., Mg(+2) into the matrix and Fe(+2) into chondrules etc.

  9. Influence of fine-grain and solid-solution strengthening on mechanical properties and in vitro degradation of WE43 alloy.

    PubMed

    Liu, Dexue; Ding, Yutian; Guo, Tingbiao; Qin, Xiaoqiong; Guo, Chenggong; Yu, Shankun; Lin, Shengling

    2014-02-01

    As one of the most important potential candidate alloys for vascular stent application, Mg-Y-Zr based Mg-4.2wt%Y-2.4wt%Nd-0.6wt%Ce(La)-0.5wt%Zr (WE43) alloys were investigated in combination with the forming processes of micro-tubes with 2.0 mm diameter and 0.1 mm wall thickness. Orthogonal experimental design for alloy composition, vacuum melting ingot, heat treatment, integrated plastic deformation and micro-tube forward extrusion are included in the processing procedures. Significant improvements in both the mechanical properties and corrosion resistance in phosphate buffered saline solution for WE43 alloys were achieved through this processing sequence. The influence of the heat treatment and hot extrusion on in vitro degradation and plasticity was found to be associated with grain size reduction and the redistribution of intermetallic particles within the microstructure. As a result, the mechanical properties and the corrosion resistance of Mg alloys can be improved through fine-grain strengthening and solid-solution strengthening to some extent.

  10. Effective inhibition of the early copper ion burst release with ultra-fine grained copper and single crystal copper for intrauterine device application.

    PubMed

    Xu, X X; Nie, F L; Wang, Y B; Zhang, J X; Zheng, W; Li, L; Zheng, Y F

    2012-02-01

    To solve the main problems of existing coarse grained copper (CG Cu) intrauterine devices (IUD)-namely burst release and a low transfer efficiency of the cupric ions during usage-ultra-fine grained copper (UFG Cu) and single crystal copper (SC Cu) have been investigated as potential substitutes. Their corrosion properties with CG Cu as a control have been studied in simulated uterine fluid (SUF) under different conditions using electrochemical measurement methods. Long-term immersion of UFG Cu, SC Cu and CG Cu samples in SUF at 37 °C have been studied for 300 days. A lower copper ion burst release and a higher efficiency release of cupric ions were observed for UFG Cu and SC Cu compared with CG Cu in the first month of immersion and 2 months later. The respective corrosion mechanisms for UFG Cu, SC Cu and CG Cu in SUF are proposed. In vitro biocompatibility tests show a better cellular response to UFG Cu and SC Cu than CG Cu. In terms of instantaneous corrosion behavior, long-term corrosion performance and in vitro biocompatibility, the three pure copper materials follow the order: UFG Cu>SC Cu>CG Cu, which indicates that UFG Cu could be the most suitable candidate material for intrauterine devices.

  11. Use of a post-production fractionation process improves the nutritional value of wheat distillers grains with solubles for young broiler chicks

    PubMed Central

    2013-01-01

    Background Post-production fractionation of wheat distillers grains with solubles (DDGS) increases their crude protein content and reduces their fiber content. This experiment was conducted to determine the effects of fractionation of wheat DDGS on apparent total tract digestibility (ATTD) and performance when fed to broiler chicks (0–21 d). Methods A total of 150, day-old, male broiler chicks (Ross-308 line; Lilydale Hatchery, Wynyard, Saskatchewan) weighing an average of 49.6 ± 0.8 g were assigned to one of five dietary treatments in a completely randomized design. The control diet was based on wheat and soybean meal and contained 20% regular wheat DDGS. The experimental diets contained 5, 10, 15 or 20% fractionated wheat DDGS added at the expense of regular wheat DDGS. Results The ATTD of dry matter and gross energy were linearly increased (P < 0.01) as the level of fractionated wheat DDGS in the diet increased. Nitrogen retention was unaffected by level of fractionated wheat DDGS (P > 0.05). Weight gain increased linearly (P = 0.05) as the level of fractionated wheat DDGS in the diet increased. Feed intake, feed conversion and mortality were unaffected by level of fractionated wheat DDGS in the diet (P > 0.05). Conclusions Post-production fractionation of wheat DDGS improves their nutritional value by lowering their fiber content and increasing their content of crude protein and energy. These changes in chemical composition supported increased weight gain of broilers fed wheat DDGS. PMID:23607764

  12. Diverse Anhydrous Silicates in a Fine-Grained Rim in the Weakly Altered CM2 Chondrite Queen Elizabeth Range 97990: Evidence for the Localized Preservation of Pristine Nebular Dust in CM Chondrites.

    NASA Astrophysics Data System (ADS)

    Brearley, A. J.

    2016-08-01

    A fine-grained rim the QUE 97990 CM2 chondrite contains diverse submicron crystalline anhydrous silicates, including olivines, low-Ca and high Ca pyroxenes and represents a more pristine sample of nebular dust than is present in most CM chondrites.

  13. Chemical fractionation of arsenic and heavy metals in fine particle matter and its implications for risk assessment: A case study in Nanjing, China

    NASA Astrophysics Data System (ADS)

    Li, Huiming; Wang, Jinhua; Wang, Qin'geng; Qian, Xin; Qian, Yu; Yang, Meng; Li, Fengying; Lu, Hao; Wang, Cheng

    2015-02-01

    A four-step sequential extraction procedure was used to study the chemical fractionation of As and heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in fine particulate matter (PM2.5) collected from Nanjing, China. The mass concentrations of most PM2.5 samples exceeded the 24 h standard (75 μg/m3) recommended by the new national ambient air quality standard of China. The most abundant elements were Fe, Zn and Pb, while As and Cd were present at the lowest concentrations. As, Cd, Cu, Mn, Pb and Zn were mostly present in the two mobile fractions, including the soluble and exchangeable fraction (F1), and carbonates, oxides and reducible fraction (F2). Fe had the highest proportion present in the residual fraction (F4). Relatively high proportions of the metals Ni and Cr were present in the oxidizable and sulfidic fraction (F3). High proportions of Zn, As and Cu and lower proportions of Cd, Cr and Fe were present in the potentially mobile phases. The enrichment factor, contamination factor and risk assessment code were calculated to analyze the main sources and assess the environmental risks of the metals in PM2.5. The carcinogenic risks of As, Cd, Ni and Pb were all lower than the accepted criterion of 10-6, whereas the carcinogenic risks of Cr for children and As and Cr for adults were higher than 10-6. The non-carcinogenic health risk of As and heavy metals because of PM2.5 exposure for children and adults were lower than but close to the safe level of 1.

  14. Fine-grained sediment gravity flow deposits induced by flood and lake slope failure events: examples of lacustrine varved sediments in Japan

    NASA Astrophysics Data System (ADS)

    Ishihara, Yoshiro; Sasaki, Yasunori; Sasaki, Hana; Onishi, Yuri

    2016-04-01

    Fine-grained sediment gravity flow deposits induced by flood and lake slope failure events are frequently intercalated in lacustrine successions. When sediment gravity flow deposits are present in varved sediments, it is suggested that they provide valuable information about sediment gravity flows, because they can easily trace laterally and can give the magnitude of erosion and recurrence interval of events. In addition, because large sedimentary bodies of stacked sediment gravity flow deposits in varved sediments of a calm lake are not suggested, a relatively simple depositional environment is expected. In the present study, we analysed sedimentary facies of sediment gravity flow deposits in varved lacustrine diatomites in the Middle Pleistocene Hiruzenbara and Miyajima formations in Japan, and concluded a depositional model of the lacustrine sediment gravity flow deposits. Varved diatomites: The Hiruzenbara Fm., a dammed lake fill as foots of Hiruzen Volcanos, is deposited during an interglacial period during MIS12 to 15. Varves of ca. 8000 yr were measured in a 20 m intercalating flood and lake slope failure-induced sediment gravity flow deposits. The Miyajima Fm., distributed in a paleo-caldera lake in NE Japan, includes many sediment gravity flow deposits possibly originated from fandeltas around the lake. These formations have differences in their depositional setting; the Hiruzebara Fm. was deposited in a large lake basin, whereas the Miyajima Fm. was deposited in a relatively small basin. Because of the depositional setting, intercalation of volcaniclastics is dominant in the Miyajima Fm. Lacustrine sediment gravity flow deposits: Sediment gravity flow deposits in both formations can be classified into flood- and lake slope failure-induced types based on the sedimentary facies. Composites of the both types are also found. Flood-induced types comprise fine-grained silts dominated by carbonaceous fragments, whereas lake slope failure-induced types are

  15. Meltwater history inferred from authigenic carbonates and fine grained glaciomarine sediments from the Mendeleev Ridge in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Nam, Seung-Il; Woo, Kyung Sik; Ji, Hyo Seon; Stein, Ruediger; Mackensen, Andreas; Matthiessen, Jens

    2015-04-01

    Authigenic carbonates and mud fractions of the glaciomarine sediments were investigated texturally and geochemically. The sediment core (PS72/410-1) was retrieved using a giant box corer from the central Mendeleev Ridge of the western Arctic Ocean (Station location= Lat. 80°30.37"N, Long. 175°44.38"W) during the Polarstern Arctic expedition (PS72) in 2008. The core is 39 cm long with age of ca. 76 ka BP and was collected from the water depth of 1,802 meters. The sediments show various colours from grey to brown as previously reported in other Arctic deep sea sediments, reflecting glacial-interglacial and/or stadial-interstadial cycles. Authigenic carbonate minerals are present through the whole sequence except for a few centimetres. These authigenic carbonates are composed of high Mg-calcite, low Mg-calcite and aragonite. Various crystal shapes of aragonite and calcite together with clear growth shapes of the crystals suggest that they are inorganic in origin. Highly enriched carbon isotope compositions (δ13C = 0 ~ +5‰ vs. PDB) strongly indicate that they formed in methanogenic zone below sediment/water interface by the reaction between anoxic pore fluids and host sediments induced by methanogenic bacteria. However, a wide range of oxygen isotope values (δ18O = -5 ~ +5‰ vs. PDB) may indicate that porewater has been changed due to reaction between residual seawater and volcanic sediments. Relatively higher contents of K, Al, Fe and Be values from muddy sediments as well as low δ18O compositions of authigenic carbonates may imply strong input of meltwater from volcanic region (Eastern Arctic region) whereas higher oxygen isotope compositions of authigenic carbonates and higher Sr and K contents of mud sediments may reflect stronger influence from carbonate-rich region (Canadian Arctic region). Mineralogical changes form low to high Mg-calcite together with decrease in Mg, Sr and Fe contents strongly support less freshwater input from glacial mode to

  16. Fine-grained parallelization of the Car-Parrinello ab initio molecular dynamics method on the IBM Blue Gene/L supercomputer

    SciTech Connect

    E. Bohm A. Bhatele L. V. Kale M. E. Tuckerman S. Kumar J. A. Gunnels G. J. Martyna; Bohm, E.; Bhatele, A.; Kale, L. V.; Tuckerman, M. E.; Kumar, S.; Gunnels, J. A.; Martyna, G. J.

    2008-01-01

    Important scientific problems can be treated via ab initio-based molecular modeling approaches, wherein atomic forces are derived from an energy Junction that explicitly considers the electrons. The Car-Parrinello ab initio molecular dynamics (CPAIMD) method is widely used to study small systems containing on the order of 10 to 103 atoms. However, the impact of CPAIMD has been limited until recently because of difficulties inherent to scaling the technique beyond processor numbers about equal to the number of electronic states. CPAIMD computations involve a large number of interdependent phases with high interprocessor communication overhead. These phases require the evaluation of various transforms and non-square matrix multiplications that require large interprocessor data movement when efficiently parallelized. Using the Charm++ parallel programming language and runtime system, the phases are discretized into a large number of virtual processors, which are, in turn, mapped flexibly onto physical processors, thereby allowing interleaving of work. Algorithmic and IBM Blue Gene/L(tm) system-specific optimizations are employed to scale the CPAIMD method to at least 30 times the number of electronic states in small systems consisting of 24 to 768 atoms (32 to 1,024 electronic states) in order to demonstrate fine-grained parallelism. The largest systems studied scaled well across the entire machine (20,480 nodes).

  17. A fine grained parallel smooth particle mesh Ewald algorithm for biophysical simulation studies: Application to the 6-D torus QCDOC supercomputer

    NASA Astrophysics Data System (ADS)

    Fang, Bin; Martyna, Glenn; Deng, Yuefan

    2007-08-01

    In order to model complex heterogeneous biophysical macrostructures with non-trivial charge distributions such as globular proteins in water, it is important to evaluate the long range forces present in these systems accurately and efficiently. The Smooth Particle Mesh Ewald summation technique (SPME) is commonly used to determine the long range part of electrostatic energy in large scale molecular simulations. While the SPME technique does not give rise to a performance bottleneck on a single processor, current implementations of SPME on massively parallel, supercomputers become problematic at large processor numbers, limiting the time and length scales that can be reached. Here, a synergistic investigation involving method improvement, parallel programming and novel architectures is employed to address this difficulty. A relatively simple modification of the SPME technique is described which gives rise to both improved accuracy and efficiency on both massively parallel and scalar computing platforms. Our fine grained parallel implementation of the modified SPME method for the novel QCDOC supercomputer with its 6D-torus architecture is then given. Numerical tests of algorithm performance on up to 1024 processors of the QCDOC machine at BNL are presented for two systems of interest, a β-hairpin solvated in explicit water, a system which consists of 1142 water molecules and a 20 residue protein for a total of 3579 atoms, and the HIV-1 protease solvated in explicit water, a system which consists of 9331 water molecules and a 198 residue protein for a total of 29508 atoms.

  18. Tectonic and climatic controls on provenance changes of fine-grained dust on the Chinese Loess Plateau since the late Oligocene

    NASA Astrophysics Data System (ADS)

    Yan, Yan; Ma, Long; Sun, Youbin

    2017-03-01

    Provenance variations of Late Cenozoic aeolian deposits on the Chinese Loess Plateau (CLP) were closely associated with regional tectonic activity and climatic change. Previous studies, however, have not reached a consensus regarding the nature and origin of past variations in source. This study presents the results of oxygen isotope (δ18O) analyses of fine-grained quartz (<16 μm) extracted from aeolian deposits on the CLP since the late Oligocene. The quartz δ18O variations exhibit distinct trends and patterns of variation over six time intervals (i.e. 25-20, 20-12, 12-7, 7-2.6, 2.6-1.2, and 1.2-0 Ma). In comparison with quartz δ18O results from East Asian dust sources and previous provenance studies of the same aeolian sequences, we identify three significant composition changes of the dust source system at around 20, 12, and 2.6 Ma. The dust source system was also rather unstable at 25-20, 12-7 and 1.2-0 Ma, while three stable stages occurred at 20-12, 7-2.6, and 2.6-1.2 Ma. The correlation between the provenance changes and paleoclimatic and tectonic evidence suggests that both tectonic and climatic factors were important in driving the observed stepwise provenance changes. However, the changes were mainly constrained by Tibetan Plateau uplift prior to the Quaternary, and by global climate change thereafter.

  19. Development of Fine-Grained, Low-Carbon Bainitic Steels with High Strength and Toughness Produced Through the Conventional Hot-Rolling and Air-Cooling

    NASA Astrophysics Data System (ADS)

    Dhua, Sanjay Kumar; Sarkar, Partha Pratim; Saxena, Atul; Jha, Bimal Kumar

    2016-12-01

    Low-carbon bainitic steels have created enormous interest among scientists across the world in the past few decades because of their high strength, toughness, and weldability replacing the conventional quenched and tempered medium-carbon steels. Three experimental steels with varying alloy additions were made in a 100-kg laboratory induction furnace and cast into 100-mm-diameter cylindrical ingots. These ingots were hot-rolled and air-cooled to 6-mm plates in an experimental rolling mill with selected thermomechanical parameters. Steels processed through this process provided an ultrafine low-carbon bainitic microstructure with maximum yield strength (YS) and ultimate tensile strength (UTS) 575 and 705 MPa, respectively. The Charpy impact toughness of the experimental steels was excellent, and at 253 K (-20 °C), it varied from 114 to 170 Joules. Cu-B-added steel was found to give an optimum combination of strength, YS-575 MPa, and toughness, 114 J at 253 K (-20 °C). Thus, fine-grained, low-carbon bainitic steels could be developed with a proper combination of alloying elements and thermomechanical parameters even by air-cooling.

  20. Sorption of Fe (Hydr)Oxides to the Surface of Shewanella putrefaciens: Cell-Bound Fine-Grained Minerals Are Not Always Formed De Novo

    PubMed Central

    Glasauer, S.; Langley, S.; Beveridge, T. J.

    2001-01-01

    Shewanella putrefaciens, a gram-negative, facultative anaerobe, is active in the cycling of iron through its interaction with Fe (hydr)oxides in natural environments. Fine-grained Fe precipitates that are attached to the outer membranes of many gram-negative bacteria have most often been attributed to precipitation and growth of the mineral at the cell surface. Our study of the sorption of nonbiogenic Fe (hydr)oxides revealed, however, that large quantities of nanometer-scale ferrihydrite (hydrous ferric oxide), goethite (α-FeOOH), and hematite (α-Fe2O3) adhered to the cell surface. Attempts to separate suspensions of cells and minerals with an 80% glycerin cushion proved that the sorbed minerals were tightly attached to the bacteria. The interaction between minerals and cells resulted in the formation of mineral-cell aggregates, which increased biomass density and provided better sedimentation of mineral Fe compared to suspensions of minerals alone. Transmission electron microscopy observations of cells prepared by whole-mount, conventional embedding, and freeze-substitution methods confirmed the close association between cells and minerals and suggested that in some instances, the mineral crystals had even penetrated the outer membrane and peptidoglycan layers. Given the abundance of these mineral types in natural environments, the data suggest that not all naturally occurring cell surface-associated minerals are necessarily formed de novo on the cell wall. PMID:11722905

  1. A fine fraction of soil used as an aerosol analogue during the DUNE experiment: sequential solubility in water, decreasing pH step-by-step

    NASA Astrophysics Data System (ADS)

    Aghnatios, C.; Losno, R.; Dulac, F.

    2014-09-01

    A soil sample collected in a desert aerosol source area near Douz (southern Tunisia) was dry-sieved at 20 μm in order to extract the fraction similar to a wind-generated aerosol, and was used to seed mesocosms during the DUNE experiment (a DUst experiment in a low Nutrient, low chlorophyll Ecosystem). In this work, said "aerosol-like" fine dust was sequentially leached by short contacts with water at initial pHs, decreasing from seven to one, representing various wet environmental conditions. For each step, the solubility of a given element is calculated as the amount of its dissolved fraction, relative to its total amount. The evolution of this fractional solubility from the highest to lowest pHs provides information on the chemical strength needed to solubilise a given element and its lability. The behaviour of the elemental solubility was sorted into two groups: (1) Ca, Sr, Ba, Mn, and P, with a solubility between 23% and 70%, and a maximum sequential solubility at pH 3; (2) Al and Fe, with a solubility of less than 2% and the highest release at pH 1. Similar solubility patterns in group 1 for Ca, P, and Mn suggest a possible association of the elements in the same minerals, most probably carbonates.

  2. Significance of fine-grained microfabrics from a Cretaceous stromatolite bed (Muñecas Fm, late Turonian, Northern Iberian Ranges, Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Martínez, Marta; Reitner, Joachim; Gil, Javier; García-Hidalgo, José; Segura, Manolo

    2010-05-01

    A fine-grained stromatolite bed of great lateral continuity (km scale) and small synoptic relief (from 15 cm up to 40 cm) is registered in the Muñecas Formation (Floquet et al., 1982), of the Northern Iberian Ranges. Muñecas Fm is mainly composed of thin-bedded limestones and marls deposited during the late Turonian. At this time, the Iberian microplate was located in subtropical palaeolatitudes (20°N-30°N according Dercourt et al., 2000) and shallow-water carbonate platform facies were deposited in a wide and shallow seaway, along a NW-SE trending, intracratonic basin (Upper Cretaceous Iberian basin), between the emergent areas of the Hesperian massif to the W and the Ebro massif to the NE (Segura et al 2002). The stromatolite bed (facies 2.1) overlies heterolithic facies (facies 1.1) composed of marls and thin-bedded, massive mudstones with micritic intraclasts, ostracods and reworked sponges, and bearing quartz-silt and bioclastic-rich wavy bands. The coeval facies, laterally equivalent to the stromatolite bed, consist of an oolite-rich, sheet-like deposit (facies 2.2). Packstone and grainstone of radial-fibrous oolites overlie burrowed bioclastic mudstone-wackestones (facies 1.2) with bivalve fragments, gastropods, foraminifers, and sponges. The stromatolite bed is capped by ostracod-rich limestones (facies 3) and marls. The stromatolite posses a stratiform to LLH macrostructure, and in some places domed bioherms up to 1 m width occur. Internally, mesostructure is composed by planar, wavy to hemispherical stromatoids. They display a broad spectrum of microestructures: dense micrite, peloids (microbial as well as bahamite peloids), clotted microfabrics, irregular micritic-wall tubes and dendroid-arborescent microframeworks (filamentous cyanobacteria?). The microfacial study of the vertical arrangement of the stromatolite laminae reveals different growth stages probably related with environmental changes. In fact, the whole fine-grained stromatolite accretion

  3. Estimations of soil fertility in physically degraded agricultural soils through selective accounting of fine earth and gravel fractions

    NASA Astrophysics Data System (ADS)

    Nagaraja, Mavinakoppa S.; Bhardwaj, Ajay Kumar; Prabhakara Reddy, G. V.; Srinivasamurthy, Chilakunda A.; Kumar, Sandeep

    2016-06-01

    Soil fertility and organic carbon (C) stock estimations are crucial to soil management, especially that of degraded soils, for productive agricultural use and in soil C sequestration studies. Currently, estimations based on generalized soil mass (hectare furrow basis) or bulk density are used which may be suitable for normal agricultural soils, but not for degraded soils. In this study, soil organic C, available nitrogen (N), available phosphorus (P2O5) and available potassium (K2O), and their stocks were estimated using three methods: (i) generalized soil mass (GSM, 2 million kg ha-1 furrow soil), (ii) bulk-density-based soil mass (BDSM) and (iii) the proportion of fine earth volume (FEV) method, for soils sampled from physically degraded lands in the eastern dry zone of Karnataka State in India. Comparative analyses using these methods revealed that the soil organic C, N, P2O and K2O stocks determined by using BDSM were higher than those determined by the GSM method. The soil organic C values were the lowest in the FEV method. The GSM method overestimated soil organic C, N, P2O and K2O by 9.3-72.1, 9.5-72.3, 7.1-66.6 and 9.2-72.3 %, respectively, compared to FEV-based estimations for physically degraded soils. The differences among the three methods of estimation were lower in soils with low gravel content and increased with an increase in gravel volume. There was overestimation of soil organic C and soil fertility with GSM and BDSM methods. A reassessment of methods of estimation was, therefore, attempted to provide fair estimates for land development projects in degraded lands.

  4. Numerical modelling of fine-grained sediments remobilization in heavily polluted streams. Case study: Elbe and Bílina River, Czech Republic.

    NASA Astrophysics Data System (ADS)

    Kaiglová, Jana; Langhammer, Jakub; Jiřinec, Petr; Janský, Bohumír; Chalupová, Dagmar

    2014-05-01

    river and the riparian sediment evaluation the 2D schematization (MIKE 21 C) was selected. It enabled to distinguish flow characteristics in the zone with complicated hydrodynamic conditions. The risk of remobilization of fine-grained sediments was evaluated in order to define a threshold discharge value after that the spreading of pollution can be expected. The major contribution of the study, realized in the framework of international iniciative ELSA was the identification of threshold values for potential remobilization of sediment burdened by old loads in different environments. These threshold values are important information for identification and mitigation of risks related with old loads and hydrological extremes. From methodological point of view the study verified validity of applied distinct approaches for fine-grained sediment remobilization assessment and identified limits for their application. Key words: sediment, remobilization, old loads, modelling, hydrodynamics, Elbe river

  5. On 10 to 30 m-scale fracture networks in Gale Crater: Contraction of fine-grained sediments due to drying or of frozen sediments due to cooling?

    NASA Astrophysics Data System (ADS)

    Sletten, Ronald; Hallet, Bernard

    2014-05-01

    The area in Gale Crater north of the Curiosity landing site has been identified as an alluvial fan [1] and features diverse geological units [2], some with abundant contraction cracks that delineate polygons on the order of 10-30 meters across. These polygons are much larger than the < 1m flagstones seen in Yellowknife by Curiosity [3] and are more suggestive of polygonal patterned ground seen at higher latitudes on Mars [4] and Earth; however, current conditions indicate that ground ice is not stable in Gale Crater [4]. Nevertheless, past conditions, e.g. obliquity changes, may have allowed permafrost to develop and ground ice to form. The domains between the larger polygons are several meters wide, which is consistent with cyclic ratcheting of ice-cemented permafrost (thermal contraction with fractures opening, debris infilling the fractures, and the fractures not closing fully when the ground warms and expands). On the other hand, the large-scale crack networks often seem to be associated with certain lithologic units, including the thinly-bedded, lightly-colored mudstones exposed at Yellowknife. This suggests that the contraction cracks defining these 10 to 30-m polygons, as well as those defining the < 1m flagstones, formed in moist fine-grained sediments that contracted upon desiccation. If the fractures were due to contraction of ice-cemented permafrost, they would be insensitive to the type of sediments they formed in because the mechanical properties would be dominated by ice. The interpretation of the larger-scale crack network is limited to satellite images since Curiosity did not visit this area, and to evidence about surface materials elsewhere in the vicinity of the rover. This evidence points to the former presence of flowing water in Gale Crater and existence of shallow lakes of relatively low salinity and near-neutral pH at Yellowknife [5]. The large amount of contraction in Yellowknife deposits is consistent with a desiccation origin in these

  6. Surface-water-quality assessment of the Yakima River basin in Washington; analysis of major and minor elements in fine-grained streambed sediment, 1987

    USGS Publications Warehouse

    Fuhrer, G.J.; McKenzie, S.W.; Rinella, J.F.; Sanzolone, R.F.; Skach, K.A.

    1993-01-01

    Fine-grained streambed sediment from the Yakima River Basin was sampled from 448 locations and analyzed for 45 elements. Anomalous major- and minor-element concentrations were based on baseline values established from element concentrations in streambed sediment in the basin. The largest number of anomalies occurred for antimony, arsenic, cerium, copper, and zinc; at least 10 percent of these element concentrations exceeded the threshold values of 0.7 mg/g (micrograms per gram), 8.5 mg/g, 57 mg/g, 40 mg/g, and 120 mg/g, respectively. Concentrations of arsenic as large as 31 and 61 mg/g occurred in streambed sediment formed from the pre-Tertiary metamorphic and intrusive rocks geologic unit and from the nonmarine sedimentary rocks geologic unit, respectively. These geologic units were probable sources of arsenic to smaller headwater streams; however, arsenic concentrations from these geologic sources rapidly attenuated downstream in the Yakima River. Geologic sources of arsenic were generally small in agricultural land-use areas; however, concentrations as large as 140 mg/g were found in samples of soils that were historically treated with the lead-arsenate pesticide. In addition, concentrations of lead, as large as 890 mg/g, occurred in these pesticide- treated soils. Streambed sediment formed from the pre-Tertiary metamorphic and intrusive rocks geologic unit also contained concentrations as large as 1,700 mg/g for chromium, 140 mg/g for cobalt, and 1,900 mg/g for nickel. Like arsenic, concentrations of chromium (in addition to mercury and nickel) were attenuated in the Yakima River. The application of zinc sulphate to orchards was probably responsible for concentrations of zinc as large as 150 mg/g in soils of and 180 mg/g in streambed sediment from the agricultural land-use area.

  7. The importance of fine-grained channel margin (FGCM) deposits in assessing the multiple residence times of suspended sediment and contaminants in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Skalak, K. J.; Pizzuto, J. E.

    2008-12-01

    We have found that fine-grained channel margin (FGCM) deposits conditioned by large woody debris (LWD) are a significant component of sediment budgets in agricultural watersheds. By volume, the deposits store about 28 percent of the annual suspended sediment load. Radiocarbon, Pb-210, and Cs-137 analyses indicate a range of sediment ages (1 year to several decades). Reservoir theory analysis indicates an average turnover time of 1.5 years and an annual mass flux equivalent to 5 percent of the annual sediment load. The power function that best fits the transit time distribution suggests that there are multiple transit times and that most sediment in the deposits is reworked on short timescales, but a portion remains in place for several decades or more. The presence of a long tail in the distribution suggests anomalous transport, which indicates a well-developed framework for subsurface contaminant transport, continuous time random walks (CTRW), could be utilized for suspended sediment transport and contaminants associated with suspended sediment. South River has a history of mercury (Hg) contamination from an industrial release that occurred 1930-1950. The distribution of ages and Hg concentrations suggest that approximately 10 percent of the sediment and 75 percent of the Hg in the deposits dates from the release period. If the sediment in FGCM deposits has been transported primarily in suspension then we can reconstruct the loading history of Hg from the plant and predict that centuries will be required to remove this material. Our approach can be generalized to assess storage of sediments and contaminants in other gravel-bed rivers.

  8. High volume methane gas hydrate deposits in fine grained sediments from the Krishna-Godavari Basin: Analysis from Micro CT scanning

    NASA Astrophysics Data System (ADS)

    Rees, E. V.; Clayton, C.; Priest, J.; Schultheiss, P. J.

    2009-12-01

    The Indian National Gas Hydrate Program (NGHP) Expedition 1, of 2006, investigated several methane gas hydrate deposits on the continental shelf around the coast of India. Using pressure coring techniques (HYACINTH and PCS), intact gas-hydrate bearing, fine-grained sediment cores were recovered during the expedition. Once recovered, these cores were rapidly depressurized and submerged in liquid nitrogen, therefore preserving the structure and form of the hydrate within the host sediment. High resolution X-Ray CT scanning was later employed to image the internal structure of the gas hydrate, analyze the trends in vein orientation, and collect volumetric data. A scanning resolution of 0.08mm allowed for a detailed view of the three-dimensional distribution of the hydrate within the sediment from which detailed analysis of vein orientation could be made. Two distinct directions of vein growth were identified in each core section studied, which suggested the presence of a specific stress regime in the Krishna-Godavari basin during hydrate formation. In addition, image segmentation of gas hydrate from the sediment allowed for volumetric analysis of the hydrate content within each core section. Results from this analysis showed that high volumes of gas hydrate, up to approximately 70% of the pore space, were present. This high volume of methane gas hydrate can have a significant impact on the stability of the host sediment if dissociation of the hydrate were to occur in-situ, through the development of excess pore pressure, increase in water content and change in salinity of the host sediment.

  9. A~fine fraction of soil used as an aerosol analogue during the DUNE experiment: sequential solubility in water with step-by-step decreasing pH

    NASA Astrophysics Data System (ADS)

    Aghnatios, C.; Losno, R.; Dulac, F.

    2014-02-01

    A soil sample collected in a desert aerosol source area near Douz (South Tunisia) was sieved at 20 μm in order to extract the fraction similar to an aerosol generated by wind and used to seed mesocosms during the DUNE experiment. In the present work, this "aerosol-like" fine dust was sequentially leached by short contacts with water at pHs decreasing from 7 to 1. These pHs are representative of various environmental wet conditions, the lowest of which could be reached during cloud conditions. The evolution of the solubility from the highest to the lowest pHs provides information on the necessary strength for the solubilisation of a given element and its lability. The behaviour of the elemental fractional solubility is sorted into two groups: (i) Ca, Sr, Ba, Mn, P constitute group 1, with a solubility between 23% and 70% and with a maximum solubility at pH 3; (ii) whereas in group 2 (Al, Fe), the solubility is less than 2% with the highest release at pH 1. Similar solubility patterns in group 1 for Ca, P and Mn suggest a~possible association of the elements in the same minerals, most probably carbonates, which gives phosphorus an unexpected high lability.

  10. Grain- and Pore-level Analysis of Drainage in Fractionally-wet Granular Media using Synchrotron X-ray Computed Microtomography

    NASA Astrophysics Data System (ADS)

    Willson, C. S.; Bradley, S.; Thompson, K. E.

    2011-12-01

    Numerous lab- and field-scale experimental studies have shown the strong impact of wettability on multiphase flow constitutive relations and how increased water repellency can lead to preferential flow paths and a heterogeneous water distribution. In conjunction, theoretical and pore-scale modeling work has been performed seeking to improve our understanding of the impact of grain-level wettability properties. Advances in high-resolution X-ray computed tomography (XCT) techniques now make it possible to nondestructively image opaque materials providing previously hard-to-observe qualitative and quantitative data and information. Furthermore, the characteristics of synchrotron X-rays make it possible to monochromatize the incident energy allowing for both k-edge absorption differencing and segmentation of fluids and materials that have even slightly different chemical composition. Concurrent with these advances has been the development of methods to extract granular packing and pore network structure data from XCT images. In this talk, we will present results from a series of experiments designed to obtain grain-, pore- and fluid-scale details during the drainage of water in fractionally-wet glass bead systems. Here, two sets of glass beads were used each having slightly different chemical compositions and thus, different X-ray absorption properties. One set was treated so that the bead surface was water neutral while the other set remained hydrophilic. Three sets of drainage experiments were conducted on three fractionally-wet systems: 100, 90, and 75% hydrophilic by weight. First, traditional lab-scale drainage experiments were performed to obtain a baseline set of characteristic drainage curves for the three systms. Next, a set of tomography-scale (i.e., 5.5 mm inner diameter column) drainage experiments were conducted in the lab to ensure that the drainage curves in the smaller columns were consistent with the lab-scale curves. Finally, tomography-scale drainage

  11. Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China.

    PubMed

    Cai, Andong; Feng, Wenting; Zhang, Wenju; Xu, Minggang

    2016-05-01

    Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, <53 μm), is important for soil organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale.

  12. Quasiclassical coarse graining and thermodynamic entropy

    SciTech Connect

    Gell-Mann, Murray; Hartle, James B.

    2007-08-15

    Our everyday descriptions of the universe are highly coarse grained, following only a tiny fraction of the variables necessary for a perfectly fine-grained description. Coarse graining in classical physics is made natural by our limited powers of observation and computation. But in the modern quantum mechanics of closed systems, some measure of coarse graining is inescapable because there are no nontrivial, probabilistic, fine-grained descriptions. This essay explores the consequences of that fact. Quantum theory allows for various coarse-grained descriptions, some of which are mutually incompatible. For most purposes, however, we are interested in the small subset of 'quasiclassical descriptions' defined by ranges of values of averages over small volumes of densities of conserved quantities such as energy and momentum and approximately conserved quantities such as baryon number. The near-conservation of these quasiclassical quantities results in approximate decoherence, predictability, and local equilibrium, leading to closed sets of equations of motion. In any description, information is sacrificed through the coarse graining that yields decoherence and gives rise to probabilities for histories. In quasiclassical descriptions, further information is sacrificed in exhibiting the emergent regularities summarized by classical equations of motion. An appropriate entropy measures the loss of information. For a 'quasiclassical realm' this is connected with the usual thermodynamic entropy as obtained from statistical mechanics. It was low for the initial state of our universe and has been increasing since.

  13. Identifying Glacio-Eustatic Forcing of Unconformities In The Canterbury Basin (IODP Exp 317) Based on Oxygen Isotope Analysis Of The Fine Fraction

    NASA Astrophysics Data System (ADS)

    Huck, C.; John, C. M.; Shevenell, A.; Shipboard Scientific Party, E.

    2010-12-01

    Sea-level rise is one of the major threats associated with anthropogenic greenhouse warming. Studies of past sea-level change are required to predict the future dynamics of ice sheets. Reconstructing past sea-levels often involves deciphering the stratigraphic record of continental margins. In marginal settings, glacials are reflected by regional unconformities in the geological record, while interglacials are represented by sedimentary deposition. However, local tectonic and oceanographic changes can also result in regional scale unconformities, which complicate stratigraphic interpretations of sea level change. The first step in any study of past sea levels is to distinguish between unconformities forced by eustasy and those forced by other mechanisms (e.g. large-scale oceanographic current changes). IODP Expedition 317 recovered Eocene to Recent sediments along a shelf-to-slope transect in the Canterbury Basin, New Zealand. The expedition sought to investigate the interplay between eustasy, local tectonics, and sedimentary transport as controls on the stratigraphic architecture of a current-dominated margin. The expedition recognized nineteen unconformities across three seismic units (late Eocene to Oligocene, early Miocene to mid-Pliocene, and mid-Pliocene to Holocene). We utilise the sediment fine fraction (<63μm) an as effective way to gain an overview of the oxygen isotopic record of the Canterbury Basin. The oxygen isotopic record of the fine fraction (δ18OFF) enables us to determine which of the nineteen Canterbury Basin unconformities were controlled by glacio-eustasy. Sequence boundaries (unconformities) controlled by glacio-eustasy are associated with a positive excursion in δ18OFF, and those related to tectonic adjustments or large-scale oceanographic changes show no association with δ18OFF. We focus on Plio-Pleistocene sediments recovered from the most distal Canterbury Basin site (IODP Site U1352), where high sedimentation rates (22-26 cm

  14. Multi-Scale Transport Properties of Fine-Grained Rocks: A Case Study of the Kirtland Formation, San Juan Basin, USA

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Dewers, T. A.; McPherson, B. J.; Wilson, T. H.; Flach, T.

    2009-12-01

    Understanding and characterizing transport properties of fine-grained rocks is critical in development of shale gas plays or assessing retention of CO2 at geologic storage sites. Difficulties arise in that both small scale (i.e., ~ nm) properties of the rock matrix and much larger scale fractures, faults, and sedimentological architecture govern migration of multiphase fluids. We present a multi-scale investigation of sealing and transport properties of the Kirtland Formation, which is a regional aquitard and reservoir seal in the San Juan Basin, USA. Sub-micron dual FIB/SEM imaging and reconstruction of 3D pore networks in core samples reveal a variety of pore types, including slit-shaped pores that are co-located with sedimentary structures and variations in mineralogy. Micron-scale chemical analysis and XRD reveal a mixture of mixed-layer smectite/illite, chlorite, quartz, and feldspar with little organic matter. Analysis of sub-micron digital reconstructions, mercury capillary injection pressure, and gas breakthrough measurements indicate a high quality sealing matrix. Natural full and partially mineralized fractures observed in core and in FMI logs include those formed from early soil-forming processes, differential compaction, and tectonic events. The potential impact of both fracture and matrix properties on large-scale transport is investigated through an analysis of natural helium from core samples, 3D seismic data and poro-elastic modeling. While seismic interpretations suggest considerable fracturing of the Kirtland, large continuous fracture zones and faults extending through the seal to the surface cannot be inferred from the data. Observed Kirtland Formation multi-scale transport properties are included as part of a risk assessment methodology for CO2 storage. Acknowledgements: The authors gratefully acknowledge the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory for sponsoring this project. The DOE’s Basic Energy Science

  15. Detecting rare, abnormally large grains by x-ray diffraction

    DOE PAGES

    Boyce, Brad L.; Furnish, Timothy Allen; Padilla, H. A.; ...

    2015-07-16

    Bimodal grain structures are common in many alloys, arising from a number of different causes including incomplete recrystallization and abnormal grain growth. These bimodal grain structures have important technological implications, such as the well-known Goss texture which is now a cornerstone for electrical steels. Yet our ability to detect bimodal grain distributions is largely confined to brute force cross-sectional metallography. The present study presents a new method for rapid detection of unusually large grains embedded in a sea of much finer grains. Traditional X-ray diffraction-based grain size measurement techniques such as Scherrer, Williamson–Hall, or Warren–Averbach rely on peak breadth andmore » shape to extract information regarding the average crystallite size. However, these line broadening techniques are not well suited to identify a very small fraction of abnormally large grains. The present method utilizes statistically anomalous intensity spikes in the Bragg peak to identify regions where abnormally large grains are contributing to diffraction. This needle-in-a-haystack technique is demonstrated on a nanocrystalline Ni–Fe alloy which has undergone fatigue-induced abnormal grain growth. In this demonstration, the technique readily identifies a few large grains that occupy <0.00001 % of the interrogation volume. Finally, while the technique is demonstrated in the current study on nanocrystalline metal, it would likely apply to any bimodal polycrystal including ultrafine grained and fine microcrystalline materials with sufficiently distinct bimodal grain statistics.« less

  16. Detecting rare, abnormally large grains by x-ray diffraction

    SciTech Connect

    Boyce, Brad L.; Furnish, Timothy Allen; Padilla, H. A.; Van Campen, Douglas; Mehta, Apurva

    2015-07-16

    Bimodal grain structures are common in many alloys, arising from a number of different causes including incomplete recrystallization and abnormal grain growth. These bimodal grain structures have important technological implications, such as the well-known Goss texture which is now a cornerstone for electrical steels. Yet our ability to detect bimodal grain distributions is largely confined to brute force cross-sectional metallography. The present study presents a new method for rapid detection of unusually large grains embedded in a sea of much finer grains. Traditional X-ray diffraction-based grain size measurement techniques such as Scherrer, Williamson–Hall, or Warren–Averbach rely on peak breadth and shape to extract information regarding the average crystallite size. However, these line broadening techniques are not well suited to identify a very small fraction of abnormally large grains. The present method utilizes statistically anomalous intensity spikes in the Bragg peak to identify regions where abnormally large grains are contributing to diffraction. This needle-in-a-haystack technique is demonstrated on a nanocrystalline Ni–Fe alloy which has undergone fatigue-induced abnormal grain growth. In this demonstration, the technique readily identifies a few large grains that occupy <0.00001 % of the interrogation volume. Finally, while the technique is demonstrated in the current study on nanocrystalline metal, it would likely apply to any bimodal polycrystal including ultrafine grained and fine microcrystalline materials with sufficiently distinct bimodal grain statistics.

  17. The relation of stream sediment surface area, grain size and composition to trace element chemistry

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.

    1987-01-01

    Intensive studies of 17 geographically and hydrologically diverse stream bed sediments provide information on the relation between grain size, surface area, and operationally defined geochemical phases (e.g. Mn oxides, amorphous Fe oxides) to trace element concentrations. Of the size fractions investigated ( 125 ??m), each of the various phases contribute to overall sample surface area. For material having mean grain sizes in the very fine sand range and finer (<125 ??m), the same phases act as surface-area inhibitors by cementing fine grains together to form aggregates. This increases the mean grain size of the sample and reduces the surface area. The presence of these aggregates may explain why the <63 ??m or <125 ??m size fractions are more important to sediment-trace element levels and surface area than other finer fractions. ?? 1987.

  18. Leaching of the fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge for the preferential removal of iron.

    PubMed

    Majuste, Daniel; Mansur, Marcelo Borges

    2009-02-15

    The fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge is a hazardous waste generated by the stainless steel industry which is normally disposed in landfills. Due to the relative high content of Fe, Cr and Ni as well as its low granulometry, a hydrometallurgical route based on sequential leaching steps is being investigated to treat it. In this paper, an attempt made to remove Fe from the sludge and concentrate Cr and Ni in the solid is highlighted. Leaching was carried out at atmospheric pressure using H(2)SO(4) and HCl at varying temperature (25, 40, 55 and 70 degrees C) and acid concentration (3, 6 and 12%, v/v). For both acids, leaching rate increased with temperature and acid concentration, and higher dissolutions of Fe and Ni were obtained in comparison with that of Cr. HCl was found more selective for Fe over Ni and Cr. The content of Fe was reduced nearly 50% (w/w) at 70 degrees C and HCl 12% (v/v), while Cr remained mostly in the solid; however, around 40% (w/w) of Ni was dissolved and it may hinder such leaching step in the studied route. The study points out that total metal leaching of sludge under high temperature and pressure conditions must be considered.

  19. The tectonic significance of K/Ar illite fine-fraction ages from the San Luis Formation (Eastern Sierras Pampeanas, Argentina)

    NASA Astrophysics Data System (ADS)

    Wemmer, Klaus; Steenken, André; Müller, Stefan; de Luchi, Mónica G. López; Siegesmund, Siegfried

    2011-04-01

    The Sierra de San Luis forms the southern tip of the Eastern Sierras Pampeanas in central Argentina. Two narrow belts of low-grade phyllites and quartz arenites, i.e. the San Luis Formation, have accommodated part of the strain-related differential exhumation of the medium- to high-grade metamorphic domains that constitute to the basement complex of the sierra. Eleven phyllite samples were subjected to the K/Ar fine-fraction dating technique. Results are interpreted in relation to the Kübler index of the illites, which indicate epimetamorphic conditions for the majority of the samples. Obtained ages between 330 and 290 Ma cover a period of compressional tectonics in the late Mississippian (Visean/Serpukhovian boundary) followed by the subsidence during the formation of the Paganzo Basin in the provinces of La Rioja and San Luis. These tectonic movements are coincident with the Toco orogeny in northern Chile and southern Bolivia. This suggests that the older K/Ar ages document the compressional stage and that younger ages record the cooling of the basement during the subsequent extensional uplift of the basement.

  20. Variability of Marine Aerosol Fine-Mode Fraction and Estimates of Anthropogenic Aerosol Component Over Cloud-Free Oceans from the Moderate Resolution Imaging Spectroradiometer (MODIS)

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Remer, Lorraine A.; Kleidman, Richard G.; Bellouin, Nicolas; Bian, Huisheng; Diehl, Thomas

    2009-01-01

    In this study, we examine seasonal and geographical variability of marine aerosol fine-mode fraction (f(sub m)) and its impacts on deriving the anthropogenic component of aerosol optical depth (tau(sub a)) and direct radiative forcing from multispectral satellite measurements. A proxy of f(sub m), empirically derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 data, shows large seasonal and geographical variations that are consistent with the Goddard Chemistry Aerosol Radiation Transport (GOCART) and Global Modeling Initiative (GMI) model simulations. The so-derived seasonally and spatially varying f(sub m) is then implemented into a method of estimating tau(sub a) and direct radiative forcing from the MODIS measurements. It is found that the use of a constant value for fm as in previous studies would have overestimated Ta by about 20% over global ocean, with the overestimation up to 45% in some regions and seasons. The 7-year (2001-2007) global ocean average tau(sub a) is 0.035, with yearly average ranging from 0.031 to 0.039. Future improvement in measurements is needed to better separate anthropogenic aerosol from natural ones and to narrow down the wide range of aerosol direct radiative forcing.

  1. Pilot Demonstration of Technology for the Production of High Value Materials from the Ultra-Fine (PM2.5) Fraction of Coal Combustion Ash

    SciTech Connect

    T. L. Robl; J. G. Groppo; R. Rathbone; B. Marrs; R. Jewell

    2008-07-18

    The overall objective of this research was to determine the feasibility of recovering a very fine fraction of fly ash, that is 5 microns in diameter or less and examining the characteristics of these materials in new or at least less traditional applications. These applications included as a polymer filler or as a 'super' pozzolanic concrete additive. As part of the effort the ash from 6 power plants was investigated and characterized. This work included collection from ESP Hoppers and ponds. The ash was thoroughly characterized chemically and physically. Froth flotation was used to reduce the carbon and testing showed that flotation could effectively reduce carbon to acceptable levels (i.e. 0.5% LOI) for most of the substrates tested. in order to enable eventual use as fillers. Hydraulic classification was used in the separation of the fine ash from the coarse ash. Hydraulic classification requires the ash to be dispersed to be effective and a range of dispersants were tested for adsorption as well as sedimentation rate. A wide range of dosages were required (0.3 to 10 g/kg). In general the ponded ash required less dispersant. A model was developed for hydraulic classification. A pilot-scale hydraulic classifier was also designed and operated for the project. Product yields of up to 21% of feed solids were achieved with recoveries of <5 {micro}m particles as high as 64%. Mean particle sizes (D{sub 50}) of the ultra fine ash (UFA) products varied from 3.7 to 10 {micro}m. A patent was filed on the classifier design. A conceptual design of a Process Demonstration Unit (PDU) with a feed rate of 2 tons of raw ash feed per hour was also completed. Pozzolanic activity was determined for the UFA ashes in mortars. In general the overall strength index was excellent with values of 90% achieved in 3 days and {approx}100% in 7 days. Three types of thermoplastic polymers were evaluated with the UFA as a filler: high density polyethylene, thermoplastic elastomer and

  2. Characterization of Grain Quality and Starch Fine Structure of Two Japonica Rice (Oryza Sativa) Cultivars with Good Sensory Properties at Different Temperatures during the Filling Stage.

    PubMed

    Zhang, Changquan; Zhou, Lihui; Zhu, Zhengbin; Lu, Huwen; Zhou, Xingzhong; Qian, Yiting; Li, Qianfeng; Lu, Yan; Gu, Minghong; Liu, Qiaoquan

    2016-05-25

    Temperature during the growing season is a critical factor affecting grain quality. High temperatures at grain filling affect kernel development, resulting in reduced yield, increased chalkiness, reduced amylose content, and poor milling quality. Here, we investigated the grain quality and starch structure of two japonica rice cultivars with good sensory properties grown at different temperatures during the filling stage under natural field conditions. Compared to those grown under normal conditions, rice grains grown under hot conditions showed significantly reduced eating and cooking qualities, including a higher percentage of grains with chalkiness, lower protein and amylose contents, and higher pasting properties. Under hot conditions, rice starch contained reduced long-chain amylose (MW 10(7.1) to 10(7.4)) and significantly fewer short-chain amylopectin (DP 5-12) but more intermediate- (DP 13-34) and long- (DP 45-60) chain amylopectin than under normal conditions, as well as higher crystallinity and gelatinization properties.

  3. The role of grain-size ratio in the mobility of mixed granular beds

    NASA Astrophysics Data System (ADS)

    Staudt, Franziska; Mullarney, Julia C.; Pilditch, Conrad A.; Huhn, Katrin

    2017-02-01

    The main goal of the study was to understand the effects of grain-size distribution on the stability of beds in the sand-silt range, which is a critical subject for the understanding of geomorphological processes in aquatic environments. Although theoretical models can explain the mobilization of a mixed bed, there is a clear lack in knowledge regarding the stabilizing effect of non-cohesive fine material. To connect existing findings, we analysed bed stability in relation to grain-size distribution in laboratory experiments. Erosion experiments in an annular flume were conducted using beds of different size compositions of spherical glass beads, i.e. a) the grain-size ratio RD = D50,coarse/D50,fine (the relative size of coarse and fine grains; D50 = 39-367 μm) and b) the amount of fines. Several glass-bead combinations with unimodal and bimodal grain-size distributions (RD = 3.9, 5.8, and 9.4) and varying fine fractions (10-40% dry weight) were subjected to increasing flow speeds (0.01-0.19 m s-1). Using acoustic Doppler velocimetry (ADV) and optical backscatter, the flow profile in the vicinity of the bed surface, the changes in bed morphology, and the suspended sediment concentration (SSC) were measured. A new method was developed to evaluate the bed-level changes detected by the ADV as a proxy for the bed mobility. We found different modes of bed mobility depending on the grain-size ratio. For low grain-size ratios, an increase in the fine fraction (to 40%) led to increased bed-level changes during the experiment and the mobilization of the mixed bed at the highest flow speed. For high ratios an increase in fine fraction (to 40%) led to a decrease of bed-level changes and the beds remained stable, i.e. no bed forms developed even at the highest flow speed. Therefore, increasing the amount of fine particles can lead to different modes of behaviour depending on the grain-size ratio. For a bimodal sediment bed with spherical grains under unidirectional flow

  4. Air classification: Potential treatment method for optimized recycling or utilization of fine-grained air pollution control residues obtained from dry off-gas cleaning high-temperature processing systems.

    PubMed

    Lanzerstorfer, Christof

    2015-11-01

    In the dust collected from the off-gas of high-temperature processes, usually components that are volatile at the process temperature are enriched. In the recycling of the dust, the concentration of these volatile components is frequently limited to avoid operation problems. Also, for external utilization the concentration of such volatile components, especially heavy metals, is often restricted. The concentration of the volatile components is usually higher in the fine fractions of the collected dust. Therefore, air classification is a potential treatment method to deplete the coarse material from these volatile components by splitting off a fines fraction with an increased concentration of those volatile components. In this work, the procedure of a sequential classification using a laboratory air classifier and the calculations required for the evaluation of air classification for a certain application were demonstrated by taking the example of a fly ash sample from a biomass combustion plant. In the investigated example, the Pb content in the coarse fraction could be reduced to 60% by separation of 20% fines. For the non-volatile Mg the content was almost constant. It can be concluded that air classification is an appropriate method for the treatment of off-gas cleaning residues.

  5. Investigating selective transport and abrasion on an alluvial fan using quantitative grain size and shape analysis

    NASA Astrophysics Data System (ADS)

    Litwin, K. L.; Jerolmack, D. J.

    2011-12-01

    Selective sorting and abrasion are the two major fluvial processes that are attributed to the downstream fining of sediments in rivers and alluvial fans. Selective transport is the process by which smaller grains are preferentially transported downstream while larger grains are deposited closer to the source. Abrasion is defined by the production of fine sediments and sand that occurs by saltation of gravel, where particle-to-particle collisions supply the energy required to break apart grains. We hypothesize that abrasion results in the gradual fining of large grains and the production of fine sands and silts, while sorting accounts for the differences in transport of these two grain-size fractions produced from abrasion, thereby creating the abrupt gravel-sand transition observed in many channel systems. In this research, we explore both selective transport and abrasion processes on the Dog Canyon alluvial fan near Alamogordo, New Mexico. We complete an extensive grain size analysis down the main channel of the fan employing an image-based technique that utilizes an autocorrelation process. We also characterize changes in grain shape using standard shape parameters, as well as Fourier analysis, which allows the study of contributions of grain roughness on a variety of length scales. Sorting appears to dominate the upper portion of the fan; the grain-size distribution narrows moving downstream until reaching a point of equal mobility, at which point sorting ceases. Abrasion exerts a subtle but persistent effect on grains during transport down the fan. Shape analysis reveals that particles become more rounded by the removal of small-scale textural features, a process that is expected to only modestly influence grain size of gravel, but should produce significant quantities of sand. This study provides a better understanding of the importance of grain abrasion and sorting on the downstream fining of channel grains in an alluvial fan, as well as an improved knowledge

  6. Impedance and AC conductivity study of nano crystalline, fine grained multiferroic bismuth ferrite (BiFeO3), synthesized by microwave sintering

    NASA Astrophysics Data System (ADS)

    Kolte, Jayant; Salame, Paresh H.; Daryapurkar, A. S.; Gopalan, P.

    2015-09-01

    In this paper, major reduction in sintering time,temperautre and significant improvement over final density of sitnered sample is reported for the microwave sintered nanocrystalline BiFeO3 (BFO) ceramic. Also, different sintering time and temperatures have been used to tailor the grain size and the final density of the resulting BFO ceramics synthesized from phase pure BFO nanoparticles ( d ¯ ≈ 10 n m ). Microwave sintering resulted in reducing the sintering time substantially (by 1h), and has resulted in submicron sized grains and high resistivity ˜1.8 GΩ-cm. The AC conductivity is seen to follow the Jonscher's power law behavior, suggesting correlated barrier hopping (CBH) mechanism in the sample. The role of oxygen vacancies at high temperature, due to volatility of bismuth, in dielectric and conductivity behavior is also discussed. Further, the sample displayed dielectric anomaly near magnetic transition temperature (˜180 °C) indicating bearing of magnetic moments on the dielectric properties. Using Impedance Spectroscopy (IS) we have established, the electrical heterogeneity of the ceramic BFO reavealing semiconducting nature of grains and insulating nature of grain boundary. This, formation of network of insulating grain boundaries and semiconducting grains could lead to formation of internal barrier layer capacitance (IBLC) leading to high dielectric constant in microwave sintered BFO.

  7. Lunar regolith fines - A source of hydrogen

    NASA Technical Reports Server (NTRS)

    Carter, J. L.

    1985-01-01

    The theoretical evaluation of the lunar regolith fines as a primary source of hydrogen reveals that a minimum order of magnitude increase in hydrogen content is possible in beneficiated fines because both particle size and particle shape play a significant role in the relationship of volume percent of surface coating to grain size. The lunar regolith fines meet the basic requirement for beneficiation because a major portion (minimum two-thirds) of the hydrogen occurs in the less than 20-micron-size fraction, a relatively small part of the fines. Beneficiation should be accomplished by a combination of vibratory screening followed by cyclone and/or possibly electrostatic separation. Early exploitation of the lunar regolith fines for hydrogen probably will be limited to hydrogen obtained as a by-product or co-product from the mining and processing for other elements or materials because a minimum of about 13,600 tons to about 19,600 tons of 100 ppm hydrogen-bearing lunar regolith fines will have to be processed with about 3,100 tons to about 4,500 tons, respectively, of concentrate heated to supply 1 ton of hydrogen, yielding a recovery of about 74 percent to about 51 percent respectively, of the hydrogen.

  8. Swash mark and grain flow

    USGS Publications Warehouse

    Sallenger,, Asbury H.

    1981-01-01

    Swash marks composed entirely of coarse sand are commonly found on coarse-sand beaches. These swash marks are 10 to 30 centimeters in width and a few millimeters to one centimeter in height. Previous observations, mostly on finer-sand beaches, indicate swash marks are seldom over a few millimeters in height and are commonly composed of material readily floated by surface tension (e.g., mica flakes and shell fragments). Swash marks composed of coarse sand have both fining seaward and fining with depth trends in grain size. Apparently, the leading margin of a wave upwash drives a highly concentrated flow of grains in which both grain size and grain velocity decrease with depth. Therefore, large grains are transported at greater velocities than are smaller grains. Thus, at the maximum advance of an upwash, a swash mark is deposited which has the observed fining seaward and fining with depth trends in grain size.

  9. Analysis of β-glucan molar mass from barley malt and brewer's spent grain with asymmetric flow field-flow fractionation (AF4) and their association to proteins.

    PubMed

    Zielke, Claudia; Teixeira, Cristina; Ding, Huihuang; Cui, Steve; Nyman, Margareta; Nilsson, Lars

    2017-02-10

    β-Glucan benefits are related with its molar mass and it would be of interest to better understand how this parameter can be changed by processing and variety for design of food with specific health effects. For this purpose, extracts from barley malts and brewers' spent grain, processed at different conditions, were analysed regarding β-glucan content, molar mass, and protein content. Molar mass distribution was assessed using asymmetric flow field-flow fractionation (AF4) with multiangle light scattering (MALS), differential refractive index (dRI) and fluorescence (FL) detection. β-Glucan was detected in a wide molar mass range, <2000 to approximately 6.7×10(6)g/mol. Differences in molar masses were more noticeable between barley varieties and steeping malting conditions than by mashing of malt. Barley products processed to preserve β-glucan contained more β-glucan of high molar mass with potential to shift the fermentation site to the distal colon. Enzymatic degradation of proteins indicated presence of aggregates containing β-glucan and protein.

  10. Corn distillers grains with solubles derived from a traditional or partial fractionation process: Growth performance and carcass characteristics of finishing feedlot heifers.

    PubMed

    Depenbusch, B E; Loe, E R; Quinn, M J; Corrigan, M E; Gibson, M L; Karges, K K; Drouillard, J S

    2008-09-01

    Six hundred ten crossbred-yearling heifers (347 +/- 5 kg of initial BW) were obtained and used in a randomized complete-block design finishing study. Finishing diets were based on steam-flaked corn and ground alfalfa hay. The control (CONT) treatment contained no distillers grains with solubles (DGS), the second diet was formulated to contained 13% (DM basis) dried corn DGS derived from a traditional dry-grind ethanol process (TRAD), and the third diet was formulated to contained 13% (DM basis) dried corn DGS derived from a partial fractionation dry-grind process (FRAC). Dry matter intake, ADG, and gain efficiency were not different (P >/= 0.48) for yearling heifers fed CONT when compared with heifers fed DGS. Heifers fed TRAD consumed more (P = 0.01) feed than heifers fed FRAC. However, ADG and feed efficiency were not different (P >/= 0.07) for heifers fed DGS. Moderate inclusion levels of DGS in finishing flaked corn diets yielded satisfactory performance. Growth performance was not different for heifers fed DGS originating from either ethanol processing method.

  11. Microstructure, Texture, and Superplasticity of a Fine-Grained Mg-Gd-Zr Alloy Processed by Equal-Channel Angular Pressing

    NASA Astrophysics Data System (ADS)

    Alizadeh, R.; Mahmudi, R.; Ngan, A. H. W.; Pereira, P. H. R.; Huang, Y.; Langdon, T. G.

    2016-12-01

    There are limited reports to date on the microstructure and superplasticity of the Mg-Gd alloys after processing by equal-channel angular pressing (ECAP). Accordingly, the effects of ECAP temperature from 473 K to 723 K (200 °C to 450 °C) and number of passes (2, 4, and 8) on the microstructure and texture of an extruded Mg-5Gd-0.4Zr (GW50) alloy were investigated by scanning electron microscope, transmission electron microscope, and electron backscattered diffraction. The results show that the optimum ECAP temperature is 623 K (350 °C). Higher temperatures give extensive grain growth and the material has insufficient formability at lower temperatures. The results show also that the alloy exhibits no further grain refinement after four ECAP passes and there is slight grain growth at 8 ECAP passes. Samples were processed by four passes at 623 K (350 °C) and then subjected to shear punch testing. The results confirm the occurrence of superplastic behavior at 723 K (450 °C) with a maximum strain rate sensitivity index of 0.47 and an activation energy of 110 kJ mol-1. The results are consistent with the occurrence of flow by grain boundary sliding in the superplastic region.

  12. A combined sol-gel and spark plasma sintering route to produce highly dense and fine-grained La0.65Ca0.20Na0.15MnO3 ceramics for magnetocaloric applications

    NASA Astrophysics Data System (ADS)

    Abdallah-Ben Ammar, Amal; Ayadi, Firas; Nowak, Sophie; Lecoq, Hélène; Cheikrouhou-Koubaa, Wissem; Cheikhrouhou, Abdelwaheb; Ammar, Souad; Sicard, Lorette

    2014-03-01

    Sol-gel chemistry and spark plasma sintering were coupled to produce fine-grained and dense La0.65Ca0.20Na0.15MnO3 ceramics and their magnetic properties were explored in order to evaluate their efficiency for domestic magnetocaloric applications. The obtained manganites crystallize in the rhombohedral symmetry (R-3c). They present grain size in the sub-micrometer range. Their density and their average grain size increase when the sintering temperature increases from 600 to 800 °C. This entails an increase of the Curie temperature (T C) and of the maximum of the magnetic entropy change, even if these values remain smaller than those measured on their bulk counterparts prepared by a conventional solid state route. However, the magnetic transition occurs on a broad temperature range, resulting in a relative cooling power reaching about 265 J Kg-1 for an applied magnetic field of 5 T. This value is very close to that previously measured on bulk La0.65Ca0.20Na0.15MnO3 ceramics and represents about 64% of that measured on the standard Gd. The ceramics produced here by a low-energy and time-consuming method can thus be considered as technically and economically valuable for the desired applications.

  13. Growth performance, feeding behavior, and selected blood metabolites of Holstein dairy calves fed restricted amounts of milk: No interactions between sources of finely ground grain and forage provision.

    PubMed

    Mirzaei, M; Khorvash, M; Ghorbani, G R; Kazemi-Bonchenari, M; Ghaffari, M H

    2017-02-01

    The objective of this study was to investigate the effects of grain sources and forage provision on growth performance, blood metabolites, and feeding behaviors of dairy calves. Sixty 3-d-old Holstein dairy calves (42.2 ± 2.5 kg of body weight) were used in a 2 × 3 factorial arrangement with the factors being grain sources (barley and corn) and forage provision (no forage, alfalfa hay, and corn silage). Individually housed calves were randomly assigned (n = 10 calves per treatment: 5 males and 5 females) to 6 treatments: (1) barley grain (BG) without forage supplement, (2) BG with alfalfa hay (AH) supplementation, (3) BG with corn silage (CS) supplementation, (4) corn grain (CG) without forage supplement, (5) CG with AH supplementation, and (6) CG with CS supplementation. All calves had ad libitum access to water and starter feed throughout the experiment. All calves were weaned on d 49 and remained in the study until d 63. Starter feed intake and average daily gain (ADG) was greater for calves fed barley than those fed corn during the preweaning and overall periods. Calves supplemented with CS had greater final body weight and postweaning as well as overall starter feed intake than AH and non-forage-supplemented calves. During the preweaning and overall periods, feeding of CS was found to increase ADG compared with feeding AH and nonforage diets. However, feed efficiency was not affected by dietary treatments. Calves supplemented with CS spent more time ruminating compared with AH and control groups; nonnutritive oral behaviors were the greatest in non-forage-supplemented calves. Regardless of the grain sources, the rumen pH value was greater for AH calves compared with CS and non-forage-supplemented calves. Blood concentration of BHB was greater for CS-supplemented calves compared with AH and non-forage-supplemented calves. Furthermore, body length and heart girth were greater for calves fed barley compared with those fed corn, and also in forage

  14. Low-Temperature Superplasticity of Ultra-Fine-Grained Ti-6Al-2Sn-4Zr-2Mo-0.1Si Alloy

    DTIC Science & Technology

    2009-03-31

    superplasticity of Ti-6Al-4V alloy utilizing dynamic globularization, i.e., the conversion of the transformed beta microstructure to a fine equiaxed...such as plasticity, creep, crack propagation and phase transformations among others. The remaining integral defined in Eq. (13) is referred to as the...quenched in water to obtain martensite microstructure with approximately 0.2-μm-thick laths (Fig. 4b). Finally, the material was cross-rolled at a

  15. SEM and TEM Observation of the Surfaces of the Fine-Grained Particles Retrieved from the Muses-C Regio on the Asteroid 25413 Itokawa

    NASA Technical Reports Server (NTRS)

    Noguchi, T.; Nakamura, T.; Zolensky, Michael E.; Tanaka, M.; Hashimoto, T.; Konno, M.; Nakato, A.; Ogami, T.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

    2011-01-01

    Surface materials on airless solar system bodies exposed to interplanetary space are gradually changed their visible to near-infrared reflectance spectra by the process called "space weathering", which makes the spectra darker and redder. Hapke et al. proposed a model of space weathering: vapor deposition of nanophase reduced iron (npFe(sup 0)) on the surfaces of the grains within the very surface of lunar regolith. This model has been proved by detailed observation of the surfaces of the lunar soil grains by transmission electron microscope (TEM). They demonstrated that npFe(sup 0) was formed by a combination of vapor deposition and irradiation effects. In other words, both micrometeorite impacts and irradiation by solar wind and galactic cosmic ray play roles on the space weathering on the Moon. Because there is a continuum of reflectance spectra from those of Q-type asteroids (almost the same as those of ordinary chondrites) to those of S-type asteroids, it is strongly suggested that reflectance spectra of asteroids composed of ordinary chondrite-like materials were modified over time to those of S-type asteroids due to space weathering. It is predicted that a small amount of npFe(sup 0) on the surface of grains in the asteroidal regolith composed of ordinary chondrite-like materials is the main agent of asteroidal space weathering.

  16. U-Th-Ra variations in Himalayan river sediments (Gandak river, India): Weathering fractionation and/or grain-size sorting?

    NASA Astrophysics Data System (ADS)

    Bosia, Clio; Chabaux, François; Pelt, Eric; France-Lanord, Christian; Morin, Guillaume; Lavé, Jérôme; Stille, Peter

    2016-11-01

    Understanding the origin of U-Th-Ra variations in the Ganga river sediments is a prerequisite for correctly using U-series nuclides to constrain the sediment transport times in Himalayan rivers. For this purpose, U, Th, and Ra concentrations, along with 238U-234U-230Th-226Ra radioactive disequilibria, were analyzed in bank, bedload and suspended sediments from the Gandak river, one of the main tributaries of the Ganga river. The data confirm that U and Th budgets of the Himalayan sediments are significantly influenced by minor resistant minerals, such as zircon, garnet and Ti-bearing minerals, the dissolution of which required the use of a high-pressure acid digestion process. Most importantly, the results indicate that the variations in (238U/232Th) and (230Th/232Th) activity ratios and 238U-234U-230Th-226Ra disequilibria in sediments along the river alluvial plain mainly reflect modifications in the mineralogical and grain-size compositions rather than the degree of weathering during transport. The (238U/232Th) and (230Th/232Th) activity ratios in the bank and bed sediments are related to variations in the minor primary minerals strongly enriched in U and Th (i.e., zircon, REE-bearing minerals and Ti-bearing minerals), whereas the activity ratios in the suspended load are related to variations in the proportions of clay, Fe-oxyhydroxides and the silt-sand fraction, which contains U- and Th-bearing minor minerals. The data also indicate that 238U-234U-230Th-226Ra disequilibria are strongly influenced by secondary mineral phases: the 230Th budget is likely mainly controlled by Fe-oxyhydroxides, and the 226Ra budget is likely mainly controlled by clay minerals. Therefore, the variations in the 238U-234U-230Th-232Th system in the sediments of the Gandak river cannot simply be interpreted as the result of fractionation due to chemical transformation of the bulk sediment during its transport within the alluvial plain and/or the result of radioactive decay. Consequently

  17. Stratification of carbon fractions and carbon management index in deep soil affected by the Grain-to-Green Program in China.

    PubMed

    Zhao, Fazhu; Yang, Gaihe; Han, Xinhui; Feng, Yongzhong; Ren, Guangxin

    2014-01-01

    Conversion of slope cropland to perennial vegetation has a significant impact on soil organic carbon (SOC) stock in A horizon. However, the impact on SOC and its fraction stratification is still poorly understood in deep soil in Loess Hilly Region (LHR) of China. Samples were collected from three typical conversion lands, Robinia psendoacacia (RP), Caragana Korshinskii Kom (CK), and abandoned land (AB), which have been converted from slope croplands (SC) for 30 years in LHR. Contents of SOC, total nitrogen (TN), particulate organic carbon (POC), and labile organic carbon (LOC), and their stratification ratios (SR) and carbon management indexes (CMI) were determined on soil profiles from 0 to 200 cm. Results showed that the SOC, TN, POC and LOC stocks of RP were significantly higher than that of SC in soil layers of 0-10, 10-40, 40-100 and 100-200 cm (P<0.05). Soil layer of 100-200 cm accounted for 27.38-36.62%, 25.10-32.91%, 21.59-31.69% and 21.08-26.83% to SOC, TN, POC and LOC stocks in lands of RP, CK and AB. SR values were >2.0 in most cases of RP, CK and AB. Moreover, CMI values of RP, CK, and AB increased by 11.61-61.53% in soil layer of 100-200 cm compared with SC. Significant positive correlations between SOC stocks and CMI or SR values of both surface soil and deep soil layers indicated that they were suitable indicators for soil quality and carbon changes evaluation. The Grain-to-Green Program (GTGP) had strong influence on improving quantity and activity of SOC pool through all soil layers of converted lands, and deep soil organic carbon should be considered in C cycle induced by GTGP. It was concluded that converting slope croplands to RP forestlands was the most efficient way for sequestering C in LHR soils.

  18. Synergistic Use of Passive Microwave and Visible to Near Infrared Data Improves Fine Scale Dynamics in Major Grain Production Areas of Russia, Ukraine, and Kazakhstan

    NASA Astrophysics Data System (ADS)

    Alemu, W. G.; Henebry, G. M.

    2014-12-01

    Many studies have used vegetation indices (VIs) and land surface temperature data derived from visible and near infrared (VNIR) sensors to study land surface phenology (LSP) and land surface seasonality (LSS). Here, we describe the synergistic use of passive microwave and VNIR data to characterize LSP and LSS in croplands. We combined passive microwave air temperature from AMSR-E with two VIs—NDVI and EVI—from MODIS to study cropland dynamics from 2003-2010 in the major grain production areas of Northern Eurasia. Using MODIS IGBP 0.05o land cover type 1 percentage data, we selected a total of 49 AMSR-E pixels at 25km spatial resolution in Ukraine (UA=14), Southern Russia (RU=24) and Northern Kazakhstan (KZ=11). Convex quadratic (CxQ) models fitted by site to growing degree-day (GDD) as a function of accumulated growing degree-days (AGDD) yielded high coefficients of determination (0.88≤ r2 ≤0.98). Deviations of GDD from the average CxQ model by site corresponded to peak VI for negative residuals and low VI at beginning and end of growing season. These patterns are understandable in terms of changes in the surface energy balance: higher latent heat flux during times of actively growing vegetation and higher sensible heat flux during periods of lower canopy evapotranspiration. Modeled thermal time to peak, i.e., AGDD at peak GDD, showed a strong inverse linear trend with respect to latitude with r2 of 0.92 for RU and KZ and 0.81 for UA. Lower latitude sites (≤48° N) that grow winter grains show either a longer unimodal growing season or a bimodal growing season; whereas, higher latitude sites (>48° N) where spring grains are cultivated show shorter, unimodal growing seasons. All sites show distinct seasonality in both GDD and VIs. Over the 8 year study period, some exhibit shifts between unimodal and bimodal LSP patterns. Regional heatwaves that devastated grain production in 2007 in UA and 2010 in RU and KZ appear anomalous from average models of GDD and

  19. Individual and cumulative effects of agriculture, forestry and metal mining activities on the metal and phosphorus content of fluvial fine-grained sediment; Quesnel River Basin, British Columbia, Canada.

    PubMed

    Smith, Tyler B; Owens, Philip N

    2014-10-15

    The impact of agriculture, forestry and metal mining on the quality of fine-grained sediment (<63 μm) was investigated in the Quesnel River Basin (QRB) (~11,500 km(2)) in British Columbia, Canada. Samples of fine-grained sediment were collected monthly during the snow-free season in 2008 using time-integrated samplers at replicate sites representative of agriculture, forestry and mining activities in the basin (i.e. "impacted" sites). Samples were also collected from replicate reference sites and also from the main stem of the Quesnel River at the downstream confluence with the Fraser River. Generally, metal(loid) and phosphorus (P) concentrations for "impacted" sites were greater than for reference sites. Furthermore, concentrations of copper (forestry and mining sites), manganese (agriculture and forestry sites) and selenium (agriculture, forestry and mining sites) exceeded upper sediment quality guideline (SQG) thresholds. These results suggest that agriculture, forestry and metal mining activities are having an influence on the concentrations of sediment-associated metal(loid)s and P in the Quesnel basin. Metal(loid) and P concentrations of sediment collected from the downstream site were not significantly greater than values for the reference sites, and were typically lower than the values for the impacted sites. This suggests that the cumulative effects of agriculture, forestry and mining activities in the QRB are presently not having a measureable effect at the river basin-scale. The lack of a cumulative effect at the basin-scale is thought to reflect: (i) the relatively recent occurrence of land use disturbances in this basin; (ii) the dominance of sediment contributions from natural forest and agriculture; and (iii) the potential for storage of contaminants on floodplains and other storage elements between the locations of disturbance activities and the downstream sampling site, which may be attenuating the disturbance signal.

  20. The Strength-Grain Size Relationship in Ultrafine-Grained Metals

    NASA Astrophysics Data System (ADS)

    Balasubramanian, N.; Langdon, Terence G.

    2016-12-01

    Metals processed by severe plastic deformation (SPD) techniques, such as equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the Hall-Petch (H-P) relationship. Examples of this behavior are discussed using experimental data for Ti, Al, and Ni. These materials typically have grain sizes greater than 50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. However, both high strength and high ductility may be achieved simultaneously by imposing high strain to obtain ultrafine-grain sizes and high fractions of high-angle grain boundaries. This facilitates grain boundary sliding, and an example is presented for a cast Al-7 pct Si alloy processed by HPT. In some materials, SPD may result in a weakening even with a very fine grain size, and this is due to microstructural changes during processing. Examples are presented for an Al-7034 alloy processed by ECAP and a Zn-22 pct Al alloy processed by HPT. In some SPD-processed materials, it is possible that grain boundary segregation and other features are present leading to higher strengths than predicted by the H-P relationship.

  1. Sand as a relevant fraction in geochemical studies in intertidal environments.

    PubMed

    Otero, X L; Huerta-Díaz, M A; De La Peña, S; Ferreira, T O

    2013-10-01

    Soil and sediment samples from several intertidal environment exposed to different types of contamination were studied to investigate the importance of grain size in relation to the capacity of the substrates to retain trace metals. The unfractionated samples (referred to as bulk samples) were separated into the following grain/size fractions: fine-coarse sand (2-0.100 mm), very fine sand (0.100-0.050 mm), silt (0.050-0.002 mm), and clay (0.002 mm). The sample into its fractions was carried out was in a glove box under high-purity N2 atmosphere in order to minimize any alterations to the samples. The bulk samples were characterized in terms of physicochemical properties such as pH, redox potential, and grain size. The total organic carbon (TOC), total sulfur (S), iron (Fe) pyrite, Fe, and manganese (Mn), and trace metals lead (Pb), mercury (Hg), chromium (Cr), and nickel (Ni) were analyzed in the bulk samples and in each fraction. The sand fractions were also examined by scanning electron microscopy (SEM). Comparisons of the above parameters were made between fractions and between each fraction and the corresponding bulk sample. The fine-coarse sand fraction contained high levels of the primary elements of the geochemical processes that occur in marine sedimentary environments such as TOC, total Fe, Mn, and S. The net concentrations of these four elements were higher in the fine-coarse sand fraction than in the very fine sand fraction and were similar to the net concentrations in the silt and clay fractions. Detailed SEM analysis of the sand coarse fraction revealed the presence of Fe and aluminum oxyhydroxide coatings in the oxic layers, whereas the framboidal pyrites and coatings observed in the anoxic layers were Fe sulfides. The presence of the various coatings explains why the trace metal concentrations in the sand fine-coarse fraction were similar to those in the clay fraction and higher than those in the very fine sand fraction. The present results

  2. Study of the Peculiarities of the Zn-Mn Phase Diagram and Their Effect on the Superplastic Behavior of Fine-Grained Zn-Mn Alloys

    NASA Astrophysics Data System (ADS)

    Lolov, Martin; Djulgerov, Nikolai; Gyurov, Stoyko

    2016-09-01

    The part of binary manganese-zinc phase diagram (alloys containing up to 2% manganese) is analyzed and the expected compositions with increased plasticity are determined in this paper. A special attention is paid to the relation between the composition, microstructure, strain rate, and plasticity of the studied alloys. The mechanical behavior during plastic deformation is analyzed and the domains of strain rate are determined, where a superplastic deformation is expected. Superplastic deformation activation energy of the studied alloys is determined on the basis of the Arrhenius theory equation. It was found that the creep deformation of Zn-0.7% Mn alloy follows the power law, or is controlled by diffusion in grain boundaries, i.e., mechanism of deformation is Coble creep, while the deformation of Zn-1.2% Mn alloy is very low and does not correspond to any of diffusion processes in Zinc.

  3. Field assisted sintering of fine-grained Li7-3xLa3Zr2AlxO12 solid electrolyte and the influence of the microstructure on the electrochemical performance

    NASA Astrophysics Data System (ADS)

    Botros, Miriam; Djenadic, Ruzica; Clemens, Oliver; Möller, Matthias; Hahn, Horst

    2016-03-01

    The synthesis and processing of fine-grained Li7-3xLa3Zr2AlxO12 (x = 0.15, 0.17, 0.20) solid electrolyte (LLZO) is performed for the first time using a combination of nebulized spray pyrolysis (NSP) and field assisted sintering technique (FAST). Using FAST, the grain growth is suppressed and highly dense ceramics with 93% of the theoretical density are obtained. A tetragonal lattice distortion is observed after the sintering process. Although this structural modification has been reported to have lower Li-ion mobility compared to the cubic modification, the total conductivity of the sample at room temperature is found to be 0.33 mS cm-1, i.e. comparable to phase-pure cubic LLZO. The activation energy of 0.38 eV is also comparable to the literature values. Galvanostatic cycling of a symmetrical cell Li|LLZO|Li shows a good cycling stability over 100 h. The interfacial resistance in contact with Li-metal is determined using alternating current impedance spectroscopy to be 76 Ω cm2 and 69 Ω cm2 before and after cycling at different current densities, respectively.

  4. Effects of Carbides on the Microstructural Evolution in Sub-micron Grain 9310 Steel During Isothermal Heat Treatment

    NASA Astrophysics Data System (ADS)

    Kozmel, Thomas; Tin, Sammy

    2015-07-01

    Recent interest in bulk ultra-fine-grained microstructures has given rise for the necessity to quantify their behavior during heat treatment should any subsequent thermal processing of the material be necessary after forming. The present study showed that the microstructure of 9310 steel forgings containing varying fractions of sub-micron grains retained some degree of stability after 4 hours of heat treatment between the temperatures of 522 K and 866 K (249 °C and 593 °C, respectively). The behavior of the microstructure during heat treatment was largely influenced by both the carbide volume fraction and distribution, which affected the level of Zener Drag present. This in effect controlled the type of growth behavior exhibited by the ferrite grains and the ability to retain the fine-grained structure.

  5. Size and modal analyses of fines and ultrafines from some Apollo 17 samples

    NASA Technical Reports Server (NTRS)

    Greene, G. M.; King, D. T., Jr.; Banholzer, G. S., Jr.; King, E. A.

    1975-01-01

    Scanning electron and optical microscopy techniques have been used to determine the grain-size frequency distributions and morphology-based modal analyses of fine and ultrafine fractions of some Apollo 17 regolith samples. There are significant and large differences between the grain-size frequency distributions of the less than 10-micron size fraction of Apollo 17 samples, but there are no clear relations to the local geologic setting from which individual samples have been collected. This may be due to effective lateral mixing of regolith particles in this size range by micrometeoroid impacts. None of the properties of the frequency distributions support the idea of selective transport of any fine grain-size fraction, as has been proposed by other workers. All of the particle types found in the coarser size fractions also occur in the less than 10-micron particles. In the size range from 105 to 10 microns there is a strong tendency for the percentage of regularly shaped glass to increase as the graphic mean grain size of the less than 1-mm size fraction decreases, both probably being controlled by exposure age.

  6. Fabric anisotropy induced by primary depositional variations in the silt: clay ratio in two fine-grained slope fan complexes: Texas Gulf Coast and northern North Sea

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, Ruarri J.; Dutton, Shirley P.; Milliken, Kitty L.; Loucks, Robert G.; Aplin, Andrew C.; Hillier, Stephen; van der Pluijm, Ben A.

    2010-04-01

    High-resolution X-ray texture goniometry (HRXTG) has been used to quantify the alignment (anisotropy) of phyllosilicate minerals in a series of diagenetically altered mudstone samples from the deep subsurface of the Texas Gulf Coast and the northern North Sea. The sampled formations have undergone a simple burial history with no overprint of tectonic deformation that may have influenced the phyllosilicate orientation. Observations have been made in two constrained temperature windows 148-150 °C (North Sea data) and 169-210 °C (Texas Gulf Coast) wherein less than 20% smectite remains in the mixed layer phase illite-smectite. Quantitative X-ray powder diffraction (XRPD) shows quartz (which is dominantly detrital) and phyllosilicate content having an inverse relationship. Quantified illite-smectite fabric intensity (phyllosilicate alignments) ranges from low alignment values of 2.42 m.r.d. (multiples of a random distribution) to high alignment values 6.75 m.r.d. and chlorite + kaolinite ranges from 1.80 to 6.46 m.r.d. We propose that the broad range of phyllosilicate fabric intensity observed reflects the range of quartz/phyllosilicate ratios that are the imprint of depositional setting, bedform truncation, and initial grain size. Detrital quartz acts to disrupt fabric intensity by being non-platy, producing areas sheltered from effective stress ('pressure shadows'), and acting as a matrix support. There is no evidence that bioturbation is a significant control on phyllosilicate alignment in these quartz/phyllosilicate mixtures. These findings have important implications for the role of grain-scale alignment on seismic anisotropy in mudstone systems. Fabric intensity in post-diagenetic samples can be predicted from (1) quartz content and (2) total clay content where: y=-7.4x+64.8 x is fabric intensity (in m.r.d.) and y is total (wt.%) quartz a=4.2b+33.7 and a is total (wt.%) clay content and b is fabric intensity (in m.r.d.).

  7. Does mycorrhizal inoculation improve plant survival, aggregate stability, and fine root development on a coarse-grained soil in an alpine eco-engineering field experiment?

    NASA Astrophysics Data System (ADS)

    Bast, A.; Wilcke, W.; Graf, F.; Lüscher, P.; Gärtner, H.

    2016-08-01

    Steep vegetation-free talus slopes in high mountain environments are prone to superficial slope failures and surface erosion. Eco-engineering measures can reduce slope instabilities and thus contribute to risk mitigation. In a field experiment, we established mycorrhizal and nonmycorrhizal research plots and determined their biophysical contribution to small-scale soil fixation. Mycorrhizal inoculation impact on plant survival, aggregate stability, and fine root development was analyzed. Here we present plant survival (ntotal = 1248) and soil core (ntotal = 108) analyses of three consecutive years in the Swiss Alps. Soil cores were assayed for their aggregate stability coefficient (ASC), root length density (RLD), and mean root diameter (MRD). Inoculation improved plant survival significantly, but it delayed aggregate stabilization relative to the noninoculated site. Higher aggregate stability occurred only after three growing seasons. Then also RLD tended to be higher and MRD increased significantly at the mycorrhizal treated site. There was a positive correlation between RLD, ASC, and roots <0.5 mm, which had the strongest impact on soil aggregation. Our results revealed a temporal offset between inoculation effects tested in laboratory and field experiments. Consequently, we recommend to establish an intermediate to long-term field experimental monitoring before transferring laboratory results to the field.

  8. Thermomagnetic Stability in Pseudo Single Domain Grains

    NASA Astrophysics Data System (ADS)

    Nagy, Lesleis; Williams, Wyn; Muxworthy, Adrian; Fabian, Karl; Conbhuí, Pádraig Ó.

    2016-04-01

    The reliability of paleomagnetic remanences are well understood for fine grains of magnetite that are single-domain (SD, uniformly magnetized). In particular Néel's theory [1] outlined the thermal energies required to block and unblock magnetic remanences. This lead to determination of thermal stability for magnetization in fine grains as outlined in Pullaiah et. al. [2] and a comprehensive understanding of SD paleomagnetic recordings. It has been known for some time that single domain magnetite is possible only in the grain size range 30 - 80nm, which may only account for a small fraction of the grain size distribution in any rock sample. Indeed rocks are often dominated by grains in the pseudo single domain (PSD) size range, at approximately 80 - 1000nm. Toward the top end of this range multi-domain features begin to dominate. In order to determine thermomagnetic stability in PSD grains we need to identify the energy barriers between all possible pairs of local energy minima (LEM) domain states as a function of both temperature and grain size. We have attempted to do this using the nudged elastic band (NEB) method [3] which searches for minimum energy paths between any given pair of LEM states. Using this technique we have determined, for the first time, complete thermomagnetic stability curves for PSD magnetite. The work presented is at a preliminary stage. However it can be shown that PSD grains of magnetite with simple geometries (e.g. cubes or cuboctahedra) have very few low energy transition paths and the stability is likely to be similar to that observed for SD grains (as expected form experimental observations). The results will provide a basis for a much more rigorous understanding of the fidelity of paleomagnetic signals in assemblages of PSD grains and their ability to retain ancient recordings of the geomagnetic field. References: [1] Néel, Louis. "Théorie du traînage magnétique des ferromagnétiques en grains fins avec applications aux terres

  9. Using an Integrated, Remote-Sensing Methodology to Evaluate the Effects of Dam Operations on Fine-Grained Sediment Storage and Sand Bar Restoration in Marble Canyon

    NASA Astrophysics Data System (ADS)

    Breedlove, M. J.; Hazel, J. E.; Kaplinski, M. A.; Schmidt, J. C.; Topping, D. J.; Rubin, D. M.; Fuller, A. E.; Tusso, R.; Gonzales, F. M.

    2005-12-01

    Eddy sand bars and other sandy deposits in and along the Colorado River in Grand Canyon National Park (GCNP) were an integral part of the pre-dam riverscape, and are still important for habitat, protection of archeological sites, and recreation. These deposits began eroding following the 1963 closure of Glen Canyon Dam that reduced the supply of sand at the upstream boundary of GCNP by about 94 % and are still eroding today. In the 1990s, resource managers and scientists began a long series of experiments and monitoring aimed at answering one primary science question. Given existing sand inputs to the ecosystem, can any set of dam operations actually restore and maintain sand bars within the Canyon? In order to test this question, a reach-based approach was developed to examine temporal and longitudinal trends in sediment storage and composition in six, 3 to 6-km reaches of the channel in Eastern GCNP. The reach-based approach integrates various remote-sensing technologies to supplement historical survey techniques. These include: LiDAR and multi-beam sonar for measuring the elevations of subaerial and subaqueous surfaces; an underwater microscope (the flying eyeball) and its subaerial sister, the beachball, for measuring the composition of sediment surfaces; and traditional surveys to provide fine-level control. Between 2000-2005, 7 distinct measurements were made for all reaches. These bracketed two high-flow experiments (controlled floods) and intermediate periods characterized by normal Dam operations. Sediment-surface changes will allow scientists to quantify system responses to specific Dam operations in attempting to address the primary science question.

  10. A precise 232Th-208Pb chronology of fine-grained monazite: Age of the Bayan Obo REE-Fe-Nb ore deposit, China

    USGS Publications Warehouse

    Wang, Jingyuan; Tatsumoto, M.; Li, X.; Premo, W.R.; Chao, E.C.T.

    1994-01-01

    We have obtained precise Th-Pb internal isochron ages on monazite and bastnaesite for the world's largest known rare earth elements (REE)-Fe-Nb ore deposit, the Bayan Obo of Inner Mongolia, China. The monazite samples, collected from the carbonate-hosted ore zone, contain extremely small amounts of uranium (less than 10 ppm) but up to 0.7% ThO2. Previous estimates of the age of mineralization ranged from 1.8 to 0.255 Ga. Magnetic fractions of monazite and bastnaesite samples (<60-??m size) showed large ranges in 232Th 204Pb values (900-400,000) and provided precise Th-Pb internal isochron ages for paragenetic monazite mineralization ranging from 555 to 398 Ma within a few percent error (0.8% for two samples). These results are the first indication that REE mineralization within the giant Bayan Obo ore deposit occurred over a long period of time. The initial lead isotopic compositions (low 206Pb 204Pb and high 208Pb 204Pb) and large negative ??{lunate}Nd values for Bayan Obo ore minerals indicate that the main source(s) for the ores was the lower crust which was depleted in uranium, but enriched in thorium and light rare earth elements for a long period of time. Zircon from a quartz monzonite, located 50 km south of the ore complex and thought to be related to Caledonian subduction, gave an age of 451 Ma, within the range of monazite ages. Textural relations together with the mineral ages favor an epigenetic rather than a syngenetic origin for the orebodies. REE mineralization started around 555 Ma (disseminated monazite in the West, the Main, and south of the East Orebody), but the main mineralization (banded ores) was related to the Caledonian subduction event ca. 474-400 Ma. ?? 1994.

  11. The influence of fine ferrite formation on the γ/α interface, fine bainite and retained austenite in a thermomechanically-processed transformation induced plasticity steel

    DOE PAGES

    Timokhina, Ilana B.; Miller, Michael K.; Beladi, Hossein; ...

    2016-03-03

    We subjected a Fe–0.26C–1.96Si–2Mn with 0.31Mo (wt%) steel to a novel thermomechanical processing route to produce fine ferrite with different volume fractions, bainite, and retained austenite. In two types of fine ferrites were found to be: (i) formed along prior austenite grain boundaries, and (ii) formed intragranularly in the interior of austenite grains. An increase in the volume fraction of fine ferrite led to the preferential formation of blocky retained austenite with low stability, and to a decrease in the volume fraction of bainite with stable layers of retained austenite. Moreover, the difference in the morphology of the bainitic ferritemore » and the retained austenite after different isothermal ferrite times was found to be responsible for the deterioration of the mechanical properties. The segregation of Mn, Mo, and C at distances of 2–2.5 nm from the ferrite and retained austenite/martensite interface on the retained austenite/martensite site was observed after 2700 s of isothermal hold. Finally, it was suggested that the segregation occurred during the austenite-to-ferrite transformation, and that this would decrease the interface mobility, which affects the austenite-to-ferrite transformation and ferrite grain size.« less

  12. Hydraulic Models for the Accumulation of Mercury-Contaminated Fine-Grained Sediment in Forested and Non-Forested Near-Bank Regions of the South River, Virginia, 1930-2007

    NASA Astrophysics Data System (ADS)

    Pizzuto, J. E.; Skalak, K.

    2010-12-01

    Mercury was released into the South River from a textile manufacturing facility in Waynesboro, Virginia, beginning in 1930. Because mercury strongly adsorbs to fine particles, it is a useful tracer for fine-grained sediment transport processes. Mercury concentrations were measured on sediment samples from 29 cores taken from near-bank environments up to 14 km downstream from the textile plant. Mercury concentrations average around 20 ppm, with a maximum of 839 ppm and a minimum of <1 ppm. The total inventory of mercury in each core ranged from 0.0008 to 0.2 kg/m^2. These data were used to calibrate simple hydraulic models of mercury accumulation at each coring site since 1930. Previous studies document the concentration of mercury on suspended sediment through time, allowing our models to estimate the history of mercury accumulation and to infer rates of sedimentation. Rating curves for each coring site were computed based on Total Station surveys of channel morphology and flow records interpolated between 3 U.S. Geological Survey gauging stations. Hydraulic roughness parameters were obtained from a HEC-RAS model calibrated to measured stage-discharge relationships. The calibrated mercury accumulation model explains 69% of the variability in the observed mercury inventories. At forested sites, each inundation event deposited an average of 0.00065 kg of mercury, while deposition at non-forested sites (mostly in pasture), averaged 0.00009 kg of mercury per event, lower by a factor of 7. At 6 sites where lateral migration increased accommodation space, mercury deposition was increased by an order of magnitude. If particle-associated mercury accumulation is assumed to result only from reduced basal shear stresses, critical shear stresses for deposition are unreasonably low, which suggests that a significant amount of the observed inventory of mercury-contaminated sediment accumulates on plant stems and leaves, rather than only being deposited on the ground. 58% of the

  13. Demonstration of Technology for the Production of High Value Materials from the Ultra-Fine (PM 2.5) Fraction of Coal Combustion Ash

    SciTech Connect

    R. S. Perrone; J. G. Groppo; T. L. Robl

    2006-07-20

    Three types of chemically and functionally different thermoplastic polymers have been chosen for evaluation with the fly ash derived filler: high density polyethylene (HDPE), thermoplastic elastomer (TPE) and polyethylene terephthalate (PET). The selections were based on volumes consumed in commercial and recycled products. The reference filler selected for comparison was 3 {micro}m calcium carbonate, a material which is commonly used with all three types of polymers. A procedure to prepare filled polymers has been developed and the polymer/filler blends have been prepared. Selected samples of filled polymers were subjected to SEM analysis to verify that the fly ash derived filler and the calcium carbonate were well dispersed. Material taken from a utility ash pond was classified using a novel combination of hydraulic and lamellar classifiers to produce an ultra-fine ash product. This product was dried and used in a series of tests to determine its potential as a filler in plastics. The general properties of the ultra-fine ash from several runs are as follows: D{sub 50}: 3-5 {micro}m; Specific gravity: {approx}2.41; Loss on ignition: 2-3%; Carbon content: 1-2%; Color: dark grey on content: 1-2%; and Morphology: spherical. The addition of fillers increased the modulus of the HDPE composite, but decreased both the offset yield stress and offset yield strain, showing that the fillers essentially made the composite stiffer but the transition to plastic deformation occurred earlier in filled HDPE as stress was applied. Similar results were obtained with TPE, however, the decrease in either stress or strain at offset yield were not as significant. Dynamic mechanical analyses (DMA) were also completed and showed that although there were some alterations in the properties of the HDPE and TPE, with the addition of CaCO{sub 3} and fly ash, the alterations are small, and more importantly, transition temperatures are not altered. A utility patent on the design of the hydraulic

  14. RESEARCH INTO A METHOD FOR IMPROVING THE QUALITY OF RECYCLED FINE AGGREGATE BY SELECTIVELY REMOVING THE BRITTLE DEFECTS

    NASA Astrophysics Data System (ADS)

    Ogawa, Hideo; Nawa, Toyoharu; Ohya, Kazu; Yamamoto, Kazuo

    Recycled aggregates have brittle defects such as cracks, pores, and voids, which comes from the residue of paste in original concrete. This report presents a method of improving the quality of recycled fine aggregate by a producing method of selectively removing the defects. Fourteen different kinds of recycled fine aggregates were manufactured by three different griding machines: joe crusher, ball mill and granulator. The influences of the characters on the recycled fine aggregates on the flowability and strength of the recycled mortar was evaluated using multiple linear regression analysis. From the results obtained in this study, it is clear that the flowability was mainly affected by both the filling fraction of recycled fine aggregate and the amount of fine powder, whereas both the compressive strength and bending strength of mortars were affected not by the filling fraction, but by the fraction of defects and the surface smoothness of the aggregates. Compareing the properties of mortar with grinding machine, it is evident that the polishing action, which is such as the ball mill or the granulator is effective both to increase the filling fraction of recycled fine aggregate and to reduce the fraction of defects in the aggregate. It was also found that the surface of grain was more irregular when the granulator was used compared with the ball mill, and hence the strength of the recycled mortar was increased.

  15. Optimization of wet shaking table process using response surface methodology applied to the separation of copper and aluminum from the fine fraction of shredder ELVs.

    PubMed

    Jordão, Helga; Sousa, António Jorge; Carvalho, M Teresa

    2016-02-01

    With the purpose of reducing the waste generated by end-of-life vehicles (ELVs) by enhancing the recovery and recycling of nonferrous metals, an experimental study was conducted with the finest size fraction of nonferrous stream produced at an ELV shredder plant. The aim of this work was to characterize the nonferrous stream and to evaluate the efficiency of a gravity concentration process in separating light and heavy nonferrous metal particles that could be easily integrated in a ELV shredder plant (in this case study the separation explicitly addressed copper and aluminum separation). The characterization of a sample of the 0-10mm particle size fraction showed a mixture of nonferrous metals with a certain degree of impurity due to the present of contaminants such as plastics. The majority of the particles exhibited a wire shape, preventing an efficient separation of materials without prior fragmentation. The gravity concentration process selected for this study was the wet shaking table and three operating parameters of the equipment were manipulated. A full factorial design in combination with a central composite design was employed to model metals recovery. Two second order polynomial equations were successfully fitted to describe the process and predict the recovery of copper and aluminum in Cu concentrate under the conditions of the present study. The optimum conditions were determined to be 11.1° of inclination, 2.8L/min of feed water flow and 4.9L/min of wash water flow. All three final products of the wet shaking table had a content higher than 90% in relation to one of the metals, wherein a Cu concentrate product was obtained with a Cu content of 96%, and 78% of Cu recovery and 2% of Al recovery.

  16. Particle-size fractionation of aeolian sand along a climatic and geomorphic gradient of the Sinai-Negev erg

    NASA Astrophysics Data System (ADS)

    Roskin, Joel; Katra, Itzhak; Blumberg, Dan G.

    2015-04-01

    This study examines changes in the aeolian sand fractions along the west-east aeolian transport path of the northern Sinai Peninsula - northwestern (NW) Negev erg of Egypt and Israel. This erg originates from the Nile Delta and is composed of currently active linear (seif) dunes in northern Sinai (its western part), and currently stabilized vegetated linear dunes (VLDs) in the NW Negev dunefield (its eastern part). Sand samples from the Nile Delta, northern Sinai and NW Negev were analyzed for particle-size distribution and sand grain morphology in accordance to their Eastern Mediterranean INQUA Dunes Atlas luminescence and radiocarbon chronologies. Linear seif dunes differ from VLDs in their vegetation cover, linearity, and dynamics. Although both are continuous landforms with similar orientations and sand-grain roundness values, the linear dunes of Sinai are coarser-grained than the Negev VLDs. The VLDs have a significantly higher proportion of very fine sand (125-50 μm) content and a varying but lower sand fining ratio defined as the ratio of fine sand percentage to very fine sand percentage. Very fine sands are suggested to have been winnowed by saltation and low suspension from source deposits and sand sheets. Detailed semi-quantitative examinations of sand grains by a SEM of a Negev VLD shows that most grains do not exhibit features that can be attributed to aeolian abrasion by sand grain-grain collisions. From these observations we infer that fractionation of sand was a major process leading to downwind fining along the studied aeolian transport path. We suggest that the very fine sand fraction of Nile Delta and Sinai sands has been transported downwind since the late middle Pleistocene. In the late Pleistocene, sand reached the NW Negev in the form of VLDs due to last-glacial period windiness of intensities unprecedented today and probably larger sediment supply. Generally current and inferred past decreasing wind velocities and increasing precipitation

  17. Pilot Demonstration of Technology for the Production of High Value Materials from the Ultra-Fine (PM 2.5) Fraction of Coal Combustion Ash

    SciTech Connect

    T.L. Robl; J.G. Groppo; Robert Rathebone

    2005-12-14

    Work on the project focused on the determination of the hydraulic classification characteristics of the Coleman and Mill Creek ashes. The work utilized the hydraulic classifier developed earlier in the project. Testing included total yield, recovery of <5 {micro}m ash diameter particles and LOI partitioning as functions of dispersant dosage and type, retention time and superficial velocity. Yields as high as 21% with recoveries of up to 2/3 of the <5 {micro}m ash fractions were achieved. Mean particle size (D{sub 50}) of varied from 3.7 to 10 {micro}m. The ashes were tested for there pozzolanic activity in mortars as measured by strength activity index using ASTM criteria. Additional testing included air entrainment reagent demand and water requirements. The classified products all performed well, demonstrating excellent early strength development in the mortars. Some increased air entrainment demand was noted. The conceptual design of a process demonstration unit PDU was also completed. A flexible, trailer-mounted field unit is envisioned.

  18. Protective barrier materials analysis: Fine soil site characterization: A research report for Westinghouse Hanford Company

    SciTech Connect

    Last, G.V.; Glennon, M.A.; Young, M.A.; Gee, G.W.

    1987-11-01

    We collected soil samples for the physical characterization of a potential fine-soil quarry site at the McGee Ranch, which is located approximately 1 km northwest of the Hanford Site's Yakima Barricade. Forty test borings were made using a hollow-stem auger. Field moisture content and grain-size distribution were determined. The samples were classified into one of 19 sediment classes based on their grain-size distributions. Maps and cross sections were constructed from both the field and laboratory data to delineate the distributions of the various sediment classes. Statistical evaluations were made to determine the variations within the fine-soil fraction of the various sediment classes. Volume estimates were then made of the amounts of soil meeting the preliminary grain-size criteria. The physical characterization of the fine soils sampled near the McGee Ranch site indicated that approximately 3.4 million cubic meters of soil met or exceeded the minimum grain-size criteria for the fine soils needed for the protective barriers program. 11 refs., 14 figs., 6 tabs.

  19. Effect of Grain Size Distribution on Processing Maps for Isothermal Compression of Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Wang, Jianguo; Liu, Dong; Hu, Yang; Yang, Yanhui; Zhu, Xinglin

    2016-02-01

    Cylindrical specimens of Inconel 718 alloys with three types of grain size distribution were used in the compression tests and processing maps were developed in 940-1040 °C and 0.001-10 s-1. The equiaxed fine grain is more effective on the dynamic softening behavior. For partial recrystallized microstructure, the peak efficiency of power dissipation occurs at the strain rate of 0.001 s-1, and the temperature range of 1000-1020 °C. In order to obtain homogeneous microstructure with fine grains, the partial recrystallized microstructure should be deformed at the low temperature and slow strain rates. The area fraction of instability domains decreases with strain increasing. The peak efficiency of power dissipation increases with average grain size decreasing. The efficiency of power dissipation will be stimulated by the precipitation of δ phase at slow strain rate of 0.001-0.01 s-1, and the initial deformed substructure at the strain rate of 0.1-1 s-1. Equiaxed fine grain is the optimum state for forging process and dynamic recrystallization. The grain size distribution has slight influence on the microstructure evolution at high temperatures.

  20. "Fine grain Nb tube for SRF cavities"

    SciTech Connect

    Robert E. Barber

    2012-07-08

    Superconducting radio frequency (SRF) cavities used in charged particle linear accelerators, are currently fabricated by deep drawing niobium sheets and welding the drawn dishes together. The Nb sheet has a non-uniform microstructure, which leads to unpredictable cavity shape and surface roughness, and inconsistent "spring-back" during forming. In addition, weld zones cause hot spots during cavity operation. These factors limit linear accelerator performance and increase cavity manufacturing cost. Equal channel angular extrusion (ECAE) can be used to refine and homogenize the microstructure of Nb tube for subsequent hydroforming into SRF cavities. Careful selection of deformation and heat treatment conditions during the processing steps can give a uniform and consistent microstructure in the tube, leading to improved deformability and lower manufacturing costs. Favorable microstructures were achieved in short test samples of RRR Nb tube, which may be particularly suitable for hydroforming into SRF cavity strings. The approach demonstrated could be applicable to microstructure engineering of other tube materials including tantalum, titanium, and zirconium.

  1. Plasticity in Ultra Fine Grained Materials

    SciTech Connect

    Koslowski, Marisol

    2015-04-15

    Understanding the mechanisms of deformation of nanocrystalline (nc) materials is critical to the design of micro and nano devices and to develop materials with superior fracture strength and wear resistance for applications in new energy technologies. In this project we focused on understanding the following plastic deformation processes described in detail in the following sections: 1. Plastic strain recovery (Section 1). 2. Effect of microstructural variability on the yield stress of nc metals (Section 2). 3. The role of partial and extended full dislocations in plastic deformation of nc metals (Section 3).

  2. Evaporation of nebular fines during chondrule formation

    NASA Astrophysics Data System (ADS)

    Wasson, John T.

    2008-06-01

    Studies of matrix in primitive chondrites provide our only detailed information about the fine fraction (diameter <2 μm) of solids in the solar nebula. A minor fraction of the fines, the presolar grains, offers information about the kinds of materials present in the molecular cloud that spawned the Solar System. Although some researchers have argued that chondritic matrix is relatively unaltered presolar matter, meteoritic chondrules bear witness to multiple high-temperature events each of which would have evaporated those fines that were inside the high-temperature fluid. Because heat is mainly transferred into the interior of chondrules by conduction, the surface temperatures of chondrules were probably at or above 2000 K. In contrast, the evaporation of mafic silicates in a canonical solar nebula occurs at around 1300 K and FeO-rich, amorphous, fine matrix evaporates at still lower temperatures, perhaps near 1200 K. Thus, during chondrule formation, the temperature of the placental bath was probably >700 K higher than the evaporation temperatures of nebular fines. The scale of chondrule forming events is not known. The currently popular shock models have typical scales of about 10 km. The scale of nebular lightning is less well defined, but is certainly much smaller, perhaps in the range 1 to 1000 m. In both cases the temperature pulses were long enough to evaporate submicrometer nebular fines. This interpretation disagrees with common views that meteoritic matrix is largely presolar in character and CI-chondrite-like in composition. It is inevitable that presolar grains (both those recognized by their anomalous isotopic compositions and those having solar-like compositions) that were within the hot fluid would also have evaporated. Chondrule formation appears to have continued down to the temperatures at which planetesimals formed, possibly around 250 K. At temperatures >600 K, the main form of C is gaseous CO. Although the conversion of CO to CH 4 at lower

  3. Fractionation of mineral species by electrophoresis

    NASA Technical Reports Server (NTRS)

    Dunning, J. D.; Herren, B. J.; Tipps, R. W.; Snyder, R. S.

    1982-01-01

    The fractionation of fine-grained aggregates into their major components is a problem in many scientific areas including earth and planetary science. Electrophoresis, the transport of electrically charged particles, immersed in a suspension medium, by a direct current field (Bier, 1959), was employed in this study as a means of separating simulated lunar soil into its constituent minerals. In these tests, conducted in a static analytical cylindrical microelectrophoresis apparatus, samples of simulated lunar soil and samples of pure mineral constituents were placed in the chamber; the electrophoretic mobilities of the lunar soil and the individual mineral constituents were measured. In most of the suspension buffers employed separability was indicated, on the basis of differences in mobility, for all the constituent mineral species except ilmenite and pyroxene, which were not efficiently separable in any of the buffers. Although only a few suspension media were employed, the success of this initial study suggests that electrophoresis may be an important mineral fractionation option in fine-grained aggregate processing.

  4. Evolution of isotopic signatures in lunar-regolith nitrogen - Noble gases and nitrogen in grain-size fractions from regolith breccia 79035

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Kim, J. S.; Kim, Y.; Marti, K.

    1992-01-01

    Ilmenite and pyroxene grain-size separates from 79035 were analyzed for trapped N; the ilmenite was also analyzed for trapped Xe. Ilmenite N contains two or more isotopically distinct trapped components differing in release temperature and therefore plausibly in implantation energy. The isotopically light, higher-temperature (higher-energy?) component has a delta N-15 value equal to -180 percent, significantly above the minimum value observed in bulk 79035, suggesting that parts of 79035 were exposed on the lunar surface earlier than the ilmenite. Using trapped Ar-40/Ar-36 and cosmogenic Ne-21 (Benkert, 1989) a compaction age of about 1 Ga was derived for the ilmenite. This implies a considerably more recent exposure than previously thought, and suggests that the long-term change in delta N-15 of regolith N was more rapid than generally believed. Comparison of these results with those for black/orange glass from 74001/74002 (compaction age 3.7 Ga; delta N-15 in the range -36 to +18 percent (Kerridge et al., 1991) indicates that the long-term trend may have followed a complex evolutionary path. Data for 79035 pyroxenes are consistent with the ilmenite compaction age but suggest a more complex exposure history.

  5. Physical and chemical effects of grain aggregates on the Palos Verdes margin, southern California

    USGS Publications Warehouse

    Drake, D.E.; Eganhouse, R.; McArthur, W.

    2002-01-01

    Large discharges of wastewater and particulate matter from the outfalls of the Los Angeles County Sanitation Districts onto the Palos Verdes shelf since 1937 have produced an effluent-affected sediment deposit characterized by low bulk density, elevated organic matter content, and a high percentage of fine silt and clay particles relative to underlying native sands and sandy silts. Comparison of the results of grain-size analyses using a gentle wet-sieving technique that preserves certain grain aggregates to the results of standard size analyses of disaggregated particles shows that high percentages (up to 50%) of the silt and clay fractions of the effluent-affected mud are incorporated in aggregates having intermediate diameters in the fine-to-medium sand size range (63-500 ??m), Scanning electron microscope images of the aggregates show that they are predominantly oval fecal pellets or irregularly shaped fragments of pellets. Deposit-feeding polychaete worms such as Capitella sp. and Mediomastus sp., abundant in the mud-rich effluent-affected sediment on Palos Verdes shelf, are probably responsible for most of the grain aggregates through fecal pellet production. Particle settling rates and densities, and the concentrations of organic carbon and p,p???-DDE, a metabolite of the hydrophobic pesticide DDT, were determined for seven grain-size fractions in the effluent-affected sediment. Fecal pellet grain densities ranged from about 1.2 to 1.5 g/cc, and their average settling rates were reduced to the equivalent of about one phi size relative to spherical quartz grains of the same diameter. However, repackaging of fine silt and clay grains into the sand-sized fecal pellets causes an effective settling rate increase of up to 3 orders of magnitude for the smallest particles incorporated in the pellets. Moreover, organic carbon and p,p???-DDE exhibit a bimodal distribution with relatively high concentrations in the finest size fraction (0-20 ??m), as expected, and a

  6. Physical and chemical effects of grain aggregates on the Palos Verdes margin, southern California

    NASA Astrophysics Data System (ADS)

    Drake, David E.; Eganhouse, Robert; McArthur, William

    2002-05-01

    Large discharges of wastewater and particulate matter from the outfalls of the Los Angeles County Sanitation Districts onto the Palos Verdes shelf since 1937 have produced an effluent-affected sediment deposit characterized by low bulk density, elevated organic matter content, and a high percentage of fine silt and clay particles relative to underlying native sands and sandy silts. Comparison of the results of grain-size analyses using a gentle wet-sieving technique that preserves certain grain aggregates to the results of standard size analyses of disaggregated particles shows that high percentages (up to 50%) of the silt and clay fractions of the effluent-affected mud are incorporated in aggregates having intermediate diameters in the fine-to-medium sand size range (63-500 μm). Scanning electron microscope images of the aggregates show that they are predominantly oval fecal pellets or irregularly shaped fragments of pellets. Deposit-feeding polychaete worms such as Capitella sp . and Mediomastus sp ., abundant in the mud-rich effluent-affected sediment on Palos Verdes shelf, are probably responsible for most of the grain aggregates through fecal pellet production. Particle settling rates and densities, and the concentrations of organic carbon and p, p'-DDE, a metabolite of the hydrophobic pesticide DDT, were determined for seven grain-size fractions in the effluent-affected sediment. Fecal pellet grain densities ranged from about 1.2 to 1.5 g/cc, and their average settling rates were reduced to the equivalent of about one phi size relative to spherical quartz grains of the same diameter. However, repackaging of fine silt and clay grains into the sand-sized fecal pellets causes an effective settling rate increase of up to 3 orders of magnitude for the smallest particles incorporated in the pellets. Moreover, organic carbon and p, p'-DDE exhibit a bimodal distribution with relatively high concentrations in the finest size fraction (0-20 μm), as expected, and a

  7. Predictive coarse-graining

    NASA Astrophysics Data System (ADS)

    Schöberl, Markus; Zabaras, Nicholas; Koutsourelakis, Phaedon-Stelios

    2017-03-01

    We propose a data-driven, coarse-graining formulation in the context of equilibrium statistical mechanics. In contrast to existing techniques which are based on a fine-to-coarse map, we adopt the opposite strategy by prescribing a probabilistic coarse-to-fine map. This corresponds to a directed probabilistic model where the coarse variables play the role of latent generators of the fine scale (all-atom) data. From an information-theoretic perspective, the framework proposed provides an improvement upon the relative entropy method [1] and is capable of quantifying the uncertainty due to the information loss that unavoidably takes place during the coarse-graining process. Furthermore, it can be readily extended to a fully Bayesian model where various sources of uncertainties are reflected in the posterior of the model parameters. The latter can be used to produce not only point estimates of fine-scale reconstructions or macroscopic observables, but more importantly, predictive posterior distributions on these quantities. Predictive posterior distributions reflect the confidence of the model as a function of the amount of data and the level of coarse-graining. The issues of model complexity and model selection are seamlessly addressed by employing a hierarchical prior that favors the discovery of sparse solutions, revealing the most prominent features in the coarse-grained model. A flexible and parallelizable Monte Carlo - Expectation-Maximization (MC-EM) scheme is proposed for carrying out inference and learning tasks. A comparative assessment of the proposed methodology is presented for a lattice spin system and the SPC/E water model.

  8. Fine-Sediment Loadings to Lake Tahoe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine-grained sediments emanating from upland and channel sources. The overall objective of the research reported here was to determine the amount of fine sediment de...

  9. Composition of grain, forage, and processed fractions from second-generation glyphosate-tolerant soybean, MON 89788, is equivalent to that of conventional soybean (Glycine max L.).

    PubMed

    Lundry, Denise R; Ridley, William P; Meyer, Jiaying J; Riordan, Susan G; Nemeth, Margaret A; Trujillo, William A; Breeze, Matthew L; Sorbet, Roy

    2008-06-25

    Developments in biotechnology and molecular-assisted breeding have led to the development of a second-generation glyphosate-tolerant soybean product, MON 89788. The MON 89788 event was produced by direct transformation of a cp4 epsps (5-enolpyruvylshikimate-3-phosphate synthase) gene cassette derived from Agrobacterium sp. strain CP4 into an elite soybean germplasm known for its superior agronomic characteristics and high yielding property. The purpose of this work was to assess whether the nutrient and antinutrient levels in seed and forage tissues of MON 89788 are comparable to those in the conventional soybean variety, A3244, which has background genetics similar to MON 89788 but does not contain the cp4 epsps gene cassette. Additional conventional soybean varieties currently in the marketplace were also included in the analysis to establish a range of natural variability for each analyte, where the range of variability is defined by a 99% tolerance interval for that particular analyte. Compositional analyses were conducted on forage, seed and four processed fractions from soybeans grown in ten sites across both the United States and Argentina during the 2004-2005 growing seasons. Forage samples were analyzed for levels of proximates (ash, fat, moisture, and protein) and fiber. Seed samples were analyzed for proximates, fiber, antinutrients, and vitamin E. Defatted, toasted (DT) meal was analyzed for proximates, fiber, amino acids, and antinutrients. Refined, bleached, and deodorized (RBD) oil was analyzed for fatty acids and vitamin E. Protein isolate was analyzed for amino acids and moisture. Crude Lecithin was analyzed for phosphatides. Results of the comparisons indicate that MON 89788 is compositionally and nutritionally equivalent to conventional soybean varieties currently in commerce.

  10. Multiple age components in individual molybdenite grains

    USGS Publications Warehouse

    Aleinikoff, John N.; Creaser, Robert A.; Lowers, Heather; Magee, Charles W.; Grauch, Richard I.

    2012-01-01

    Re–Os geochronology of fractions composed of unsized, coarse, and fine molybdenite from a pod of unusual monazite–xenotime gneiss within a granulite facies paragneiss, Hudson Highlands, NY, yielded dates of 950.5 ± 2.5, 953.8 ± 2.6, and 941.2 ± 2.6 Ma, respectively. These dates are not recorded by co-existing zircon, monazite, or xenotime. SEM–BSE imagery of thin sections and separated grains reveals that most molybdenite grains are composed of core and rim plates that are approximately perpendicular. Rim material invaded cores, forming irregular contacts, probably reflecting dissolution/reprecipitation. EPMA and LA-ICP-MS analyses show that cores and rims have different trace element concentrations (for example, cores are relatively enriched in W). On the basis of inclusions of zircon with metamorphic overgrowths, we conclude that molybdenite cores and rims formed after high-grade regional metamorphism. The discovery of cores and rims in individual molybdenite grains is analogous to multi-component U-Pb geochronometers such as zircon, monazite, and titanite; thus, molybdenite should be carefully examined before dating to ensure that the requirement of age homogeneity is fulfilled.

  11. Grain boundary wetness of partially molten dunite

    NASA Astrophysics Data System (ADS)

    Mu, S.; Faul, U.

    2013-12-01

    The grain scale melt distribution plays a key role for physical properties of partially molten regions in Earth's upper mantle, but our current understanding of the distribution of basaltic melt at the grain scale is still incomplete. A recent experimental study shows that wetted two-grain boundaries are a common feature of partially molten dunite at small melt fractions (Garapic et al., G3, 2013). In early ideal models which assume isotropic surface energy, the grain scale melt distribution is uniquely determined by knowing the melt fraction and the dihedral angle between two crystalline grains and the melt (von Bargen and Waff, JGR, 1986). Olivine is anisotropic in surface energy, hence the grain scale melt distribution at given melt fraction cannot be characterized by the dihedral angle alone. The grain boundary wetness, which is defined as the ratio of solid-liquid boundary area over the total interfacial area (Takei, JGR, 1998), is a more objective measure of the grain scale melt distribution. The aim of this study is to quantify the relationship between grain size, melt fraction, temperature and grain boundary wetness of partially molten dunite under dry conditions. We annealed olivine-basalt aggregates with melt fractions from 0.03% to 6% at a range of temperatures and 1 GPa in a piston cylinder for 1 to 336 hours, with resulting mean grain sizes of 10 to 60 μm. The samples were sectioned, polished and imaged at high resolution by using a field emission SEM. Each image had a size of 2048 x 1536 pixels with a resolution of 0.014 to 0.029 μm/pixel, depending on magnification. For each sample, depending on grain sizes, we made mosaics of 3 x 3 or 6 x 6 overlapping images. Measurements of melt fraction, grain boundary wetness and grain size were carried out on these high resolution mosaics by using ImageJ software. Analyses of mosaics show that grain boundary wetness increases with increasing melt fraction at constant grain size to values well above those

  12. Fine Arts.

    ERIC Educational Resources Information Center

    Danzer, Gerald A.; Newman, Mark

    1992-01-01

    Discusses the use of fine arts as sources to enrich the study of history. Suggests that such works will serve as barometers of change, examples of cross-cultural influences, and political messages. Includes suggestions of works and artists from different historic periods. (DK)

  13. Direct soil contact values for ecological receptors exposed to weathered petroleum hydrocarbon (PHC) fraction 2.

    PubMed

    Angell, Robin A; Kullman, Steve; Shrive, Emma; Stephenson, Gladys L; Tindal, Miles

    2012-11-01

    Ecological tier 1 Canada-wide standards (CWS) for petroleum hydrocarbon (PHC) fraction 2 (F2; >nC10-C16) in soil were derived using ecotoxicological assessment endpoints (effective concentrations [ECs]/lethal concentrations [LCs]/inhibitory concentrations, 25% [IC25s]) with freshly spiked (fresh) fine- and coarse-grained soils. These soil standards might be needlessly conservative when applied to field samples with weathered hydrocarbons. The purpose of the present study was to assess the degradation and toxicity of weathered PHC F2 in a fine-grained soil and to derive direct soil contact values for ecological receptors. Fine-grained reference soils were spiked with distilled F2 and weathered for 183 d. Toxicity tests using plants and invertebrates were conducted with the weathered F2-spiked soils. Endpoint EC/IC25s were calculated and used to derive soil standards for weathered F2 in fine-grained soil protective of ecological receptors exposed via direct soil contact. The values derived for weathered F2 were less restrictive than current ecological tier 1 CWS for F2 in soil.

  14. Three dimensional analysis of the pore space in fine-grained Boom Clay, using BIB-SEM (broad-ion beam scanning electron microscopy), combined with FIB (focused ion-beam) serial cross-sectioning, pore network modeling and Wood's metal injection

    NASA Astrophysics Data System (ADS)

    Hemes, Susanne; Klaver, Jop; Desbois, Guillaume; Urai, Janos

    2014-05-01

    The Boom Clay is, besides the Ypresian clays, one of the potential host rock materials for radioactive waste disposal in Belgium (Gens et al., 2003; Van Marcke & Laenen, 2005; Verhoef et al., 2011). To access parameters, which are relevant for the diffusion controlled transport of radionuclides in the material, such as porosity, pore connectivity and permeability, it is crucial to characterize the pore space at high resolution (nm-scale) and in 3D. Focused-ion-beam (FIB) serial cross-sectioning in combination with high resolution scanning electron microscopy (SEM), pore network modeling, Wood's metal injection and broad-ion-beam (BIB) milling, constitute a superior set of methods to characterize the 3D pore space in fine-grained, clayey materials, down to the nm-scale resolution. In the present study, we identified characteristic 3D pore space morphologies, determined the 3D volume porosity of the material and applied pore network extraction modeling (Dong and Blunt, 2009), to access the connectivity of the pore space and to discriminate between pore bodies and pore throats. Moreover, we used Wood's metal injection (WMI) in combination with BIB-SEM imaging to assess the pore connectivity at a larger scale and even higher resolution. The FIB-SEM results show a highly (~ 90 %) interconnected pore space in Boom Clay, down to the resolution of ~ 3E+03 nm³ (voxel-size), with a total volume porosity of ~ 20 %. Pore morphologies of large (> 5E+08 nm³), highly interconnected pores are complex, with high surface area to volume ratios (shape factors G ~ 0.01), whereas small (< 1E+06 nm³), often isolated pores are much more compact and show higher shape factors (G) up to 0.03. WMI in combination with BIB-SEM, down to a resolution of ~ 50 nm² pixel-size, indicates an interconnected porosity fraction of ~ 80 %, of a total measured 2D porosity of ~ 20 %. Determining and distinguishing between pore bodies and pore throats enables us to compare 3D FIB-SEM pore

  15. Submicrometer Organic Grains: Widespread Constituents of the Early Solar System

    NASA Technical Reports Server (NTRS)

    Messenger, Scott; Nakamuri-Messenger, Keiko; Keller, Lindsay; Matrajt, Graciela; Clemett, Simon; Ito, Motoo

    2007-01-01

    Primitive meteorites and interplanetary dust particles (IDPs) contain remants of interstellar organic matter, marked by anomalous H and N isotopic ratios. These isotopic anomalies are attributed to mass fractionation during chemical reactions at cryogenic temperatures (10-100K) in a cold molecular cloud. Significant variations in the chemistry and isotopic compositions of organic compounds within and between these samples suggest varying histories of alteration and dilution of the presolar components. Recent studies have reported large H and N isotopic anomalies preserved in sub-m organic inclusions in both meteorites and IDPs. In the Tagish Lake meteorite, the largest H and N isotopic anomalies are associated with sub-m, hollow organic globules. The common physical, chemical, and isotopic characteristics of these globules suggest that they formed before being incorporated into their parent meteorite. These organic globules probably originated as organic ice coatings that formed on preexisting ice or mineral grains in a cold molecular cloud. Radiation driven photochemistry may have processed them into refractory organic grains. This model implies that submicrometer organic grains were widely distributed throughout the solar nebula during the epoch of planet formation. Submicrometer organic particles were detected by the Giotto and Vega encounters with comet Halley, termed CHON particles based on their major element chemistry. The first direct samples of cometary dust (comet Wild-2) were returned by the Stardust spacecraft in January 2006. These samples exhibit widely varying, fine grained mineralogy similar to anhydrous IDPs, including submicrometer carbonaceous grains. The submicrometer organic grains from comet Wild-2 exhibit H and N isotopic anomalies of similar magnitude to those commonly observed in primitive meteorites and IDPs. Isotopically anomalous, submicrometer organic grains have now been observed in meteorites, IDPs, the Oort-cloud comet Halley, and

  16. Grain boundary character distribution in nanocrystalline metals produced by different processing routes

    SciTech Connect

    Bober, David B.; Kumar, Mukal; Rupert, Timothy J.; Khalajhedayati, Amirhossein

    2015-12-28

    Nanocrystalline materials are defined by their fine grain size, but details of the grain boundary character distribution should also be important. Grain boundary character distributions are reported for ball-milled, sputter-deposited, and electrodeposited Ni and Ni-based alloys, all with average grain sizes of ~20 nm, to study the influence of processing route. The two deposited materials had nearly identical grain boundary character distributions, both marked by a Σ3 length percentage of 23 to 25 pct. In contrast, the ball-milled material had only 3 pct Σ3-type grain boundaries and a large fraction of low-angle boundaries (16 pct), with the remainder being predominantly random high angle (73 pct). Furthermore, these grain boundary character measurements are connected to the physical events that control their respective processing routes. Consequences for material properties are also discussed with a focus on nanocrystalline corrosion. As a whole, the results presented here show that grain boundary character distribution, which has often been overlooked in nanocrystalline metals, can vary significantly and influence material properties in profound ways.

  17. Grain boundary character distribution in nanocrystalline metals produced by different processing routes

    DOE PAGES

    Bober, David B.; Kumar, Mukal; Rupert, Timothy J.; ...

    2015-12-28

    Nanocrystalline materials are defined by their fine grain size, but details of the grain boundary character distribution should also be important. Grain boundary character distributions are reported for ball-milled, sputter-deposited, and electrodeposited Ni and Ni-based alloys, all with average grain sizes of ~20 nm, to study the influence of processing route. The two deposited materials had nearly identical grain boundary character distributions, both marked by a Σ3 length percentage of 23 to 25 pct. In contrast, the ball-milled material had only 3 pct Σ3-type grain boundaries and a large fraction of low-angle boundaries (16 pct), with the remainder being predominantlymore » random high angle (73 pct). Furthermore, these grain boundary character measurements are connected to the physical events that control their respective processing routes. Consequences for material properties are also discussed with a focus on nanocrystalline corrosion. As a whole, the results presented here show that grain boundary character distribution, which has often been overlooked in nanocrystalline metals, can vary significantly and influence material properties in profound ways.« less

  18. New grain formation during warm deformation of ferritic stainless steel

    SciTech Connect

    Belyakov, A.; Sakai, Taku; Kaibyshev, R.

    1998-01-01

    Microstructural evolution accompanied by localization of plastic flow was studied in compression of a ferritic stainless steel with high stacking fault energy (SFE) at 873 K ({approx} 0.5 Tm). The structure evolution is characterized by the formation of dense dislocation walls at low strains and subsequently of microbands and their clusters at moderate strains, followed by the evolution of fragmented structure inside the clusters of microbands at high strains. The misorientations of the fragmented boundaries and the fraction of high-angle grain boundaries increase substantially with increasing strain. Finally, further straining leads to the formation of new fine grains with high-angle boundaries, which become more equiaxed than the previous fragmented structure. The mechanisms operating during such structure changes are discussed in detail.

  19. Fines classification based on sensitivity to pore-fluid chemistry

    USGS Publications Warehouse

    Jang, Junbong; Santamarina, J. Carlos

    2016-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil “electrical sensitivity.” Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.

  20. Grain size trends reveal alluvial fan sensitivity to late Pleistocene climate change

    NASA Astrophysics Data System (ADS)

    Whittaker, A. C.; D'Arcy, M. K.; Roda Boluda, D. C.

    2015-12-01

    The effects of climate change on eroding landscapes and the sedimentary record remain poorly understood. The measurement of grain size fining rates in stream-flow dominated deposits provides one way to address this issue because, in principle, these trends embed important information about the dynamics of sediment routing systems and their sensitivities to external forcing. At a fundamental level, downstream fining is often driven by selective deposition of sediment. The relative efficiency of this process is determined by the physical characteristics of the input sediment supply and the spatial distribution of subsidence rate, which generates the accommodation necessary for mass extraction. Here, we measure grain size fining rates from apex to toe on two alluvial fan systems in northern Death Valley, California, which have well-exposed modern and 70 ka surfaces, where the long-term tectonic boundary conditions are known and where climatic variation over this time period is well-constrained. We integrate a self-similar gravel fraction fining model, based on selective sediment extraction, with cosmogenically-derived catchment erosion rates and gravel fining data, to estimate the change in sediment flux that occurred between 70 ka and the present day. Our results show that a 30 % decrease in average precipitation rate led to a 20 % decrease in sediment flux and a clear increase in the down-fan rate of fining. This supports existing landscape evolution models that relate a decrease in precipitation rate to a decrease in sediment flux, but implies that this relationship may be sub-linear. This study offers a new approach to applying grain size fining models to mountain catchments and their alluvial fan systems, and shows fan stratigraphy can be highly sensitive to climate changes over <105 years. However we also observe that this sensitivity is lost when sediment is remobilised and recycled over a time period longer than the duration of the climatic perturbation.

  1. Can Wet Rocky Granular Flows Become Debris Flows Due to Fine Sediment Production by Abrasion?

    NASA Astrophysics Data System (ADS)

    Arabnia, O.; Sklar, L. S.; Bianchi, G.; Mclaughlin, M. K.

    2015-12-01

    Debris flows are rapid mass movements in which elevated pore pressures are sustained by a viscous fluid matrix with high concentrations of fine sediments. Debris flows may form from coarse-grained wet granular flows as fine sediments are entrained from hillslope and channel material. Here we investigate whether abrasion of the rocks within a granular flow can produce sufficient fine sediments to create debris flows. To test this hypothesis experimentally, we used a set of 4 rotating drums ranging from 0.2 to 4.0 m diameter. Each drum has vanes along the boundary ensure shearing within the flow. Shear rate was varied by changing drum rotational velocity to maintain a constant Froude Number across drums. Initial runs used angular clasts of granodiorite with a tensile strength of 7.6 MPa, with well-sorted coarse particle size distributions linearly scaled with drum radius. The fluid was initially clear water, which rapidly acquired fine-grained wear products. After each 250 m tangential distance, we measured the particle size distributions, and then returned all water and sediment to the drums for subsequent runs. We calculate particle wear rates using statistics of size and mass distributions, and by fitting the Sternberg equation to the rate of mass loss from the size fraction > 2mm. Abundant fine sediments were produced in the experiments, but very little change in the median grain size was detected. This appears to be due to clast rounding, as evidenced by a decrease in the number of stable equilibrium resting points. We find that the growth in the fine sediment concentration in the fluid scales with unit drum power. This relationship can be used to estimate fine sediment production rates in the field. We explore this approach at Inyo Creek, a steep catchment in the Sierra Nevada, California. There, a significant debris flow occurred in July 2013, which originated as a coarse-grained wet granular flow. We use surveys to estimate flow depth and velocity where super

  2. Concepts on Low Temperature Mechanical Grain Growth

    SciTech Connect

    Sharon, John Anthony; Boyce, Brad Lee

    2013-11-01

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

  3. New Technology/Old Technology: Comparing Lunar Grain Size Distribution Data and Methods

    NASA Technical Reports Server (NTRS)

    Fruland, R. M.; Cooper, Bonnie L.; Gonzalexz, C. P.; McKay, David S.

    2011-01-01

    Laser diffraction technology generates reproducible grain size distributions and reveals new structures not apparent in old sieve data. The comparison of specific sieve fractions with the Microtrac distribution curve generated for those specific fractions shows a reasonable match for the mean of each fraction between the two techniques, giving us confidence that the large existing body of sieve data can be cross-correlated with new data based on laser diffraction. It is well-suited for lunar soils, which have as much as 25% of the material in the less than 20 micrometer fraction. The fines in this range are of particular interest because they may contain a record of important space weathering processes.

  4. ChemCam analysis of Martian fine dust

    NASA Astrophysics Data System (ADS)

    Lasue, Jeremie; Mangold, Nicolas; Cousin, Agnes; Meslin, Pierre-Yves; Wiens, Roger; Gasnault, Olivier; Rapin, William; Schroder, Susanne; Ollila, Ann; Fabre, Cécile; Berger, Gilles; Le Mouélic, Stéphane; Dehouck, Erwin; Forni, Olivier; Maurice, Sylvestre; Anderson, Ryan; Bridges, Nathan; Clark, Benton; Clegg, Samuel; d'Uston, Claude; Goetz, Walter; Johnson, Jeffrey R.; Lanza, Nina; Madsen, Morten; Melikechi, Noureddine; Newsom, Horton; Sautter, Violaine; Martin-Torres, Javier; Zorzano, Maria-Paz; MSL Science Team

    2016-10-01

    In this work, we examine the chemical composition of dust observed by the Chemistry Camera (ChemCam) instrument onboard the Mars Science Laboratory (MSL) rover at Gale Crater. The Laser Induced Breakdown Spectroscopy technique analyses samples without preparation, which allows detection of the elemental composition of surface deposits. Mars aeolian fine dust (<2-3 microns) composition is analyzed on the first shot of each Mars target. It is reproducible over time and present a composition characteristic of the global martian fine dust, which covers the entire planet and contributes to the local geology analyzed by MSL. Its composition can also be retrieved on the ChemCam Calibration Targets (CCCT) by subtraction of the well characterized CCCT spectra. The CCCT include eight glasses and ceramics that have been generated to simulate Martian rocks of interest and two targets of a single element (graphite for carbon and an alloy of titanium). ChemCam passive spectroscopy also indicates varying deposition of the dust cover on the CCCT.Major elements are quantified and shown to be very similar to the fine soils encountered at Gale crater. The composition is also similar to the soils and fine dust measured by APXS for the elements common to both instruments. The minor elements quantified by ChemCam (Ba, Sr, Rb, Li, Mn, Cr) are within the range of soil surveys, but we see a higher concentration of Li than in other types of remotely characterized targets. Sulfur is possibly detected at the ChemCam limit of detection. Hydrogen is clearly identified, indicating that this fine dust is a contributor to the H content of the martian soils, as also detected by the SAM and CheMin instruments, and provides constraints as to which fraction of the Martian surface is hydrated and altered. In conclusion, the finest fraction of dust particles on the surface of Mars contains hydrated components mixed intimately within the fine aeolian dust fraction, suggesting that this dust likely

  5. Composite circumstellar dust grains

    NASA Astrophysics Data System (ADS)

    Gupta, Ranjan; Vaidya, Dipak B.; Dutta, Rajeshwari

    2016-10-01

    We calculate the absorption efficiencies of composite silicate grains with inclusions of graphite and silicon carbide in the spectral range 5-25 μm. We study the variation in absorption profiles with volume fractions of inclusions. In particular we study the variation in the wavelength of peak absorption at 10 and 18 μm. We also study the variation of the absorption of porous silicate grains. We use the absorption efficiencies to calculate the infrared flux at various dust temperatures and compare with the observed infrared emission flux from the circumstellar dust around some M-type and asymptotic giant branch stars obtained from IRAS and a few stars from Spitzer satellite. We interpret the observed data in terms of the circumstellar dust grain sizes, shape, composition and dust temperature.

  6. Grain size control of rhenium strip

    NASA Technical Reports Server (NTRS)

    Schuster, Gary B.

    1991-01-01

    Ensuring the desired grain size in the pure Re strip employed by the SP-100 space nuclear reactor design entails the establishment of an initial grain size in the as-received strip and the avoidance of excessive grain growth during subsequent fabrication. Pure Re tapered tensile specimens have been fabricated and tested in order to quantify the effects of grain-boundary migration. Grain size could be rendered fine and uniform by means of a rolling procedure that uses rather large reductions between short intermediate anneals. The critical strain regime varies inversely with annealing temperature.

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

    NASA Astrophysics Data System (ADS)

    Sha, Qingyun; Li, Guiyan; Li, Dahang

    2013-12-01

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

  8. Visualization of post-sedimentary grain size reduction in loess sequences by calculation of laser diffraction patterns with two different optical models

    NASA Astrophysics Data System (ADS)

    Schulte, Philipp; Lehmkuhl, Frank

    2016-04-01

    Loess is predominantly accumulated during glacial periods. During interglacial and interstadial periods soils are developed. Soil formation usually results in a reduction of the particle grain size. In Loess sediments the post-depositional grain size variation is due to a reduction of the dominating coarse silt fraction in favor of an increasing of the clay fraction. The fine and medium silt fractions also increase in most cases. Generally there are two post depositional fractionation processes which are responsible for this grain size shift: (1) the chemical weathering of silt sized minerals like mica and feldspar as a result of Hydration and Hydrolysis, (2) the physical weathering of all containing minerals by cryogenic processes. There are many widely used proxies to estimate the vertical variation and the different intensities of the post-depositional weathering. However, there are uncertainties related to aeolian sorting effects, the distance to the source regions and carbonate dynamics, which reduces the sensitivity of common proxies to the chemical weathering. In this study we present a simple and quick method using laser diffraction calculations obtained by two different optical models to highlight the enrichment of fine grained material by the transformation and neoformation of pedogenic minerals.

  9. The physics of grain-grain collisions and gas-grain sputtering in interstellar shocks

    NASA Technical Reports Server (NTRS)

    Tielens, A. G. G. M.; Mckee, C. F.; Seab, C. G.; Hollenbach, D. J.

    1994-01-01

    Grain-grain collisions and ion sputtering destroy dust grains in interstellar shocks. An analytical theory is developed for the propagation of shock waves in solids driven by grain-grain collisions, which compares very favorably with detailed numerical calculations. This theory is used to determine the fraction of grain vaporized by a grain-grain collision. Our results predict much less vaporization of colliding grains in interstellar shocks than previous estimates. This theory can also be used to determine the fraction of a colliding grain that melts, shatter, or undergoes a phase transformation to a higher density phase. In particular, the latter two processes can be much more important in interstellar shocks than vaporization. The sputtering of grains by impacting gas ions is reanalyzed based upon extensive laboratory studies and a theoretically derived 'universal'sputtering relation. The analytical results are compared to available experimental studies of sputtering of graphite/amorphous carbon, SiO2, SiC, Fe, and H2O. Sputtering yields for astrophysically relevant materials as a function of impact energy and ion mass are derived. These yields are also averaged over thermal impact spectrum and simple polynomial fits to the resulting yields as a function of temperature are presented. The derived sputtering yields are similar to those adopted in previous studies, except for graphite near threshold where the new yields are much larger due to a lower adopted binding energy. The ion bombardment will amorphitize the surface layers of interstellar grains. It will also convert graphite into hydrogenated amorphous carbon (HAC) to a depth of 10-20 A. It is suggested that these HAC surfaces are the carriers of the 3.4 micrometer absorption feature in the interstellar medium.

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

    NASA Astrophysics Data System (ADS)

    DeCost, Brian L.; Holm, Elizabeth A.

    2016-07-01

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

  11. Grain refinement control in TIG arc welding

    NASA Technical Reports Server (NTRS)

    Iceland, W. F.; Whiffen, E. L. (Inventor)

    1975-01-01

    A method for controlling grain size and weld puddle agitation in a tungsten electrode inert gas welding system to produce fine, even grain size and distribution is disclosed. In the method the frequency of dc welding voltage pulses supplied to the welding electrode is varied over a preselected frequency range and the arc gas voltage is monitored. At some frequency in the preselected range the arc gas voltage will pass through a maximum. By maintaining the operating frequency of the system at this value, maximum weld puddle agitation and fine grain structure are produced.

  12. Method for synthesizing fine-grained phosphor powders of the type (RE.sub.1- Ln.sub.x)(P.sub.1-y V.sub.y)O.sub.4

    DOEpatents

    Phillips, Mark L. F.

    1998-01-01

    A method for generating well-crystallized photo- and cathodoluminescent oxide phosphor powders. The method of this invention uses hydrothermal synthesis and annealing to produce nearly monosized (RE.sub.1-x Ln.sub.x)(P.sub.1-y V.sub.y)O.sub.4 (Ln.dbd.Ce.fwdarw.Lu) phosphor grains with crystallite sizes from 0.04 to 5 .mu.m. Such phosphors find application in cathode-ray tube, flat-panel, and projection displays.

  13. Only pick the right grains: Modelling the bias due to subjective grain-size interval selection for chronometric and fingerprinting approaches.

    NASA Astrophysics Data System (ADS)

    Dietze, Michael; Fuchs, Margret; Kreutzer, Sebastian

    2016-04-01

    Many modern approaches of radiometric dating or geochemical fingerprinting rely on sampling sedimentary deposits. A key assumption of most concepts is that the extracted grain-size fraction of the sampled sediment adequately represents the actual process to be dated or the source area to be fingerprinted. However, these assumptions are not always well constrained. Rather, they have to align with arbitrary, method-determined size intervals, such as "coarse grain" or "fine grain" with partly even different definitions. Such arbitrary intervals violate principal process-based concepts of sediment transport and can thus introduce significant bias to the analysis outcome (i.e., a deviation of the measured from the true value). We present a flexible numerical framework (numOlum) for the statistical programming language R that allows quantifying the bias due to any given analysis size interval for different types of sediment deposits. This framework is applied to synthetic samples from the realms of luminescence dating and geochemical fingerprinting, i.e. a virtual reworked loess section. We show independent validation data from artificially dosed and subsequently mixed grain-size proportions and we present a statistical approach (end-member modelling analysis, EMMA) that allows accounting for the effect of measuring the compound dosimetric history or geochemical composition of a sample. EMMA separates polymodal grain-size distributions into the underlying transport process-related distributions and their contribution to each sample. These underlying distributions can then be used to adjust grain-size preparation intervals to minimise the incorporation of "undesired" grain-size fractions.

  14. Grain Size Variability and Sea Ice in Middle to Late Quaternary Sediments along the Lomonosov Ridge, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gyllencreutz, R.; O'Regan, M.; Lowemark, L. A.; Jakobsson, M.

    2014-12-01

    The main transport mechanisms for coarse grained sediments to the central Arctic Ocean are entrainment in sea ice and ice bergs. However, grain size distributions in the fine fraction have not been studied in sufficient detail to understand different transport and sedimentation patterns. Here we present analysis of fine fraction grain size spectrums in middle and late Quaternary sediments recovered from a suite of cores collected from the Lomonosov Ridge in the central Arctic Ocean that span a large range of water depths (>3000 to <1000 m). The grain size data are plotted in 3D, resembling a topographic map, which greatly facilitates interpretation. Glacial periods are characterized as distinct coarsening events with larger variability, down to the marine isotope stage 6/7 boundary. Below this level, glacial and interglacial periods are marked by more distinct changes in the silt and clay fractions. Throughout the record, the coarser intervals are distinct in all studied grain sizes, i.e. when the >63 um increases, clay and silt also show coarsening, which has been described previously, but is more clearly visible in our 3D-visualization of the particle size distributions. This supports previous studies showing that this pattern is consistent with grain size distributions in modern sea-ice. The results strengthen the evidence that a large portion of the silt in the central Arctic Ocean is transported by sea ice. Similar results are found in stratigraphically aligned intervals from cores recovered from widely differing water depths, possibly providing a means to differentiate influences of sea ice rafting from current controlled sorting.

  15. Method for synthesizing fine-grained phosphor powders of the type (RE{sub 1{minus}x}Ln{sub x})(P{sub 1{minus}y}V{sub y})O{sub 4}

    DOEpatents

    Phillips, M.L.F.

    1998-04-28

    A method for generating well-crystallized photo- and cathodoluminescent oxide phosphor powders is disclosed. The method of this invention uses hydrothermal synthesis and annealing to produce nearly monosized (RE{sub 1{minus}x}Ln{sub x})(P{sub 1{minus}y}V{sub y}O{sub 4}) (Ln{double_bond}Ce{yields}Lu) phosphor grains with crystallite sizes from 0.04 to 5 {micro}m. Such phosphors find application in cathode-ray tube, flat-panel, and projection displays. 4 figs.

  16. Luna 24 regolith breccias: A possible source of the fine size material of the Luna 24 regolith

    NASA Technical Reports Server (NTRS)

    Rode, O. D.; Lindstrom, M. M.

    1994-01-01

    The regolith breccias from the Luna 24 core were analyzed. The Luna 24 regolith is a mixture of fine and coarse grain materials. The comparable analysis of the grain size distributions, the modal and chemical compositions of the breccias, and the regolith from the same levels show that the friable slightly litificated breccia with a friable fine grain matrix may be a source of fine grain material of the Luna 24 present day regolith.

  17. The workability of 'XD' titanium aluminide alloys with low volume fractions of TiB2

    SciTech Connect

    Szaruga, A.; Rothenflue, L.; Srinivasan, R.; Lipsitt, H.A. )

    1992-05-01

    A determination is made of the effect of lowering the volume fraction of titanium diboride on the workability of the Ti-48Al-2Mn-2Nb titanium aluminide alloy. It is found that the workability of the low-TiB2 alloys is similar to that of alloys containing 7.5 TiB2; the improved workability of these alloys is accordingly considered to be due to the control of grain size that is achieved by the dispersion of a hard stable phase. While a volume fraction of 0.5 percent was insufficient for consistent retention of fine grain size, alloys with 1-2 vol pct TiB2 deformed uniformly at high temperatures. 6 refs.

  18. Short- and medium-term grain size changes in deltaic beaches (Ebro Delta, NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Guillén, Jorge; Palanques, Albert

    1996-01-01

    The beach sediment of the Ebro Delta shows significant temporal grain size changes unrelated with seasonal processes. The evolution of the grain size during the 1988-1991 period shows coarsening and fining variations, with a general coarsening trend which ranges from 2.10 to 1.96 phi (about 8 · 10 -3 mm/year). This low-magnitude grain size change is considered significant because it is indicated by both mean values from the data set (textural zones) and individualized sampling points. The coarsening trend of the beach sediment in the Ebro Delta is mainly caused by the sedimentary deficit affecting the Ebro coast. The finer sand fractions of the sediment are progressively winnowed from the initial beach deposit without being replaced by new river sediment supplies. Superimposed on the general coarsening trend there exist grain size variations that may be related with processes of a shorter period such as changes in the sediment supplied from the river into the nearshore zone, variations in the wave energy affecting the beach, and man-induced actions, such as beach nourishment. The mean grain size of beach sediment sampled 20 years ago indicates that the coarsening gradient measured during the study period cannot be extrapolated to longer periods of time (decades). This work shows that processes of a different temporal scale but a similar magnitude must be integrated in order to explain the evolution of sediment grain size in deltaic beaches.