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Sample records for clay particle orientation

  1. Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

    NASA Astrophysics Data System (ADS)

    Lim, A. J. M. S.; Syazwani, R. N.; Wijeyesekera, D. C.

    2016-07-01

    Understanding the engineering properties of the mineralogy and microfabic of clayey soils is very complex and thus very difficult for soil characterization. Micromechanics of soils recognize that the micro structure and mineralogy of clay have a significant influence on its engineering behaviour. To achieve a more reliable quantitative evaluation of clay mineralogy, a proper sample preparation technique for quantitative clay mineral analysis is necessary. This paper presents the quantitative evaluation of elemental analysis and chemical characterization of oriented and random oriented clay particles using X-ray spectroscopy. Three different types of clays namely marine clay, bentonite and kaolin clay were studied. The oriented samples were prepared by placing the dispersed clay in water and left to settle on porous ceramic tiles by applying a relatively weak suction through a vacuum pump. Images form a Scanning Electron Microscope (SEM) was also used to show the comparison between the orientation patterns of both the sample preparation techniques. From the quantitative analysis of the X-ray spectroscopy, oriented sampling method showed more accuracy in identifying mineral deposits, because it produced better peak intensity on the spectrum and more mineral content can be identified compared to randomly oriented samples.

  2. A Study on the Effect of Clay Particle Orientation on Diffusion in Compacted Bentonite

    SciTech Connect

    Sato, H.

    2002-02-26

    In this study, the effect of the orientation of clay particles on diffusion in compacted bentonite, which is regarded to be quite important as a candidate buffer material in safety assessment for a geological disposal of high-level radioactive waste, was experimentally discussed by investigating effective diffusion coefficients (De) for tritiated water (HTO), which is non-sorptive onto bentonite. The diffusion experiments were carried out for 2 kinds of smectite contents of Na-bentonites, Kunigel-V1{reg_sign} (content of Na-smectite, 46-49wt%) and Kunipia-F{reg_sign} (content of Na-smectite, > 99wt%) at dry densities of 1.0 and 1.5 Mg/m3 by a through-diffusion method. The through-diffusion experiments were carried out for the same direction as compacted direction of bentonite and perpendicular direction to compacted direction. Scanning electron microscopic (SEM) observations for the cross section of bentonite in the axial and perpendicular directions to compacted direction of bentonite were also carried out at dry densities of 1.0, 1.6, and 2.0 Mg/m3. Although De values for Kunigel-V1{reg_sign} were approximately the same for both diffusion directions to compacted direction over the densities, and no anisotropy in De was found, De values in the perpendicular direction to compacted direction for Kunipia-F{reg_sign} were clearly higher than those in the same direction as compacted direction. In the SEM observations, no significant orientation of clay particles was found for Kunigel-V1{reg_sign} over the densities, while the orientation of clay particles was clearly found for Kunipia-F{reg_sign}, and the degree of the orientation of clay particles became significant with an increase in dry density of bentonite. This tendency is in good agreement with that for De values obtained, indicating that smectite content in bentonite affects the orientation property of clay particles, and that the orientated clay particles affect diffusion pathway.

  3. X-ray Scattering Measurements of Particle Orientation in a Sheared Polymer/Clay Dispersion

    SciTech Connect

    Pujari, Saswati; Dougherty, Leah; Mobuchon, Christoph; Carreau, Pierre J.; Heuzey, Marie-Claude; Burghardt, Wesley R.

    2012-01-20

    We report steady and transient measurements of particle orientation in a clay dispersion subjected to shear flow. An organically modified clay is dispersed in a Newtonian polymer matrix at a volume fraction of 0.02, using methods previously reported by Mobuchon et al. (Rheol Acta 46: 1045, 2007). In accord with prior studies, mechanical rheometry shows yield stress-like behavior in steady shear, while time dependent growth of modulus is observed following flow cessation. Measurements of flow-induced orientation in the flow-gradient plane of simple shear flow using small-angle and wide-angle X-ray scattering (SAXS and WAXS) are reported. Both SAXS and WAXS reveal increasing particle orientation as shear rate is increased. Partial relaxation of nanoparticle orientation upon flow cessation is well correlated with time-dependent changes in complex modulus. SAXS and WAXS data provide qualitatively similar results; however, some quantitative differences are attributed to differences in the length scales probed by these techniques.

  4. Clay Mineral Preferred Orientation

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, R. J.

    2014-12-01

    Anisotropy of the orientation of clay minerals, often referred to as texture, may be unique to sediments' deposition, composition, deformation or diagenetic history. The literature is rich with studies that include preferred orientation generation in fault gouge, low-grade metamorphic rocks, sediments with variable clay content and during the smectite-to-illite transformation. Untangling the interplay between many competing factors in any one geologic situation has proven a significant challenge over many years. Understanding how, where and when clay minerals develop a preferred orientation has significant implications for permeability anisotropy in shallow burial, the way mechanical properties are projected from shallower to deeper settings in basin modeling packages and the way velocity anisotropy is accounted for in seismic data processing. The assessment of the anisotropic properties of fine-grained siliciclastic rocks is gaining significant momentum in rock physics research. Therefore, a fundamental understanding of how clay minerals develop a preferred orientation in space and time is crucial to the understanding of anisotropy of physical properties. The current study brings together a wealth of data that may be used in a predictive sense to account for fabric anisotropy that may impact any number of rock properties.

  5. Fine particle clay catalysts for coal liquefaction

    SciTech Connect

    Olson, E.S.

    1991-01-01

    The efficient production of environmentally acceptable distillate fuels requires catalysts for hydrogenation and cleavage of the coal macromolecules and removal of oxygen, nitrogen, and sulfur heteroatoms. The goal of the proposed research is to develop new catalysts for the direct liquefaction of coal. This type of catalyst consists of fine clay particles that have been treated with reagents which form pillaring structures between the aluminosilicate layers of the clay. The pillars not only hold the layers apart but also constitute the active catalytic sites for hydrogenation of the coal and the solvent used in the liquefaction. The pillaring catalytic sites are composed of pyrrhotite, which has been previously demonstrated to be active for coal liquefaction. The pyrrhotite sites are generated in situ by sulfiding the corresponding oxyiron species. The size of the catalyst will be less than 40 nm in order to promote intimate contact with the coal material. Since the clays and reagents for pillaring and activating the clays are inexpensive, the catalysts can be discarded after use, rather than regenerated by a costly process. The proposed work will evaluate methods for preparing the fine particle iron-pillared clay dispersions and for activating the particles to generate the catalysts. Characterization studies of the pillared clays and activated catalysts will be performed. The effectiveness of the pillared clay dispersion for hydrogenation and coal liquefaction will be determined in several types of testing.

  6. Fine particle clay catalysts for coal liquefaction

    SciTech Connect

    Olson, E.S.

    1991-01-01

    The efficient production of environmentally acceptable distillate fuels requires catalysts for hydrogenation and cleavage of the coal macromolecules and removal of oxygen, nitrogen, and sulfur heteroatoms. The goal of the proposed research is to develop new catalysts for the direct liquefaction of coal. This type of catalyst consists of fine clay particles that have been treated with reagents which form pillaring structures between the aluminosilicate layers of the clay. The pillars not only hold the layers apart but also constitute the active catalytic sites for hydrogenation of the coal and solvent used in the liquefaction. The pillaring catalytic sites are composed of pyrrhotite, which has been previously demonstrated to be active for coal liquefaction. The pyrrhotite sites are generated in situ by sulfiding the corresponding oxyiron species. The size of the catalyst will be less than 40 nm in order to promote intimate contact with the coal material. Since the clays and reagents for pillaring and activating the clays are inexpensive, the catalysts can be discarded after use, rather than regenerated by a costly process. The proposed work will evaluate methods for preparing the fine particle iron-pillared clay dispersions and for activating the particles to generate the catalysts. Characterization studies of the pillared clays and activated catalysts will performed. The effectiveness of the pillared clay dispersion for hydrogenation and coal liquefaction will be determined in several types of testing. 5 refs., 1 tab.

  7. Shear-Induced Orientation in Well-Exfoliated Polystyrene/Clay Nanocomposites

    SciTech Connect

    Dykes, Laura M.C.; Torkelson, John M.; Burghardt, Wesley R.

    2012-03-26

    We report measurements of shear-induced particle orientation in highly exfoliated polystyrene/clay nanocomposites. Samples were prepared using an in situ polymerization technique, in which native clay is organically modified with a cationic surfactant that incorporates a polymerizable vinylbenzyl moiety. Controlled radical polymerization was used during the synthesis to limit the molecular weight and polydispersity of the nanocomposite polymer matrix. Flow-induced orientation was measured in the flow-gradient plane of shear flow using synchrotron-based small-angle X-ray scattering. Despite the small rotational diffusivity expected for the clay particles, significant particle orientation was only observed at relatively high rates in steady shear or at high frequencies in large-amplitude oscillatory shear. Measurements of orientation upon flow cessation provided direct evidence of a structural relaxation process that was orders of magnitude faster than estimates of rotational Brownian motion. It is suggested that this fast relaxation arises from either relaxation of shear-induced distortion of partially flexible exfoliated clay sheets in a highly entangled nanoparticle network or coupling of particle and polymer dynamics.

  8. Sedimentation of athermal particles in clay suspensions

    NASA Astrophysics Data System (ADS)

    Clotet, Xavier; Kudrolli, Arshad

    2015-03-01

    We discuss sedimentation of athermal particles in dense clay suspensions which appear liquid-like to glass-like. These studies are motivated by the physics important to a diverse range of problems including remediation of oil sands after the extraction of hydrocarbons, and formation of filter cakes in bore wells. We approach this problem by first considering collective sedimentation of athermal spherical particles in a viscous liquid in quasi-two dimensional and three dimensional containers. We examine the system using optical and x-ray tomography techniques which gives particle level information besides global information on the evolution of the volume fraction. Unlike sediments in the dilute limit - which can be modeled as isolated particles that sediment with a constant velocity and slow down exponentially as they approach the bottom of the container - we find interaction between the particles through the viscous fluids leads to qualitatively differences. We find significant avalanching behavior and cooperative motion as the grains collectively settle, and non-exponential increase in settling time. We discuss the effect of stirring caused by the sedimenting particles on their viscosity and consequently the sedimentation rates as a function of particle concentration. Supported by Petroleum Research Fund Grant PRF # 54045-ND9.

  9. Effect of sonication on the particle size of montmorillonite clays.

    PubMed

    Poli, Alessandra L; Batista, Tatiana; Schmitt, Carla C; Gessner, Fergus; Neumann, Miguel G

    2008-09-15

    This paper reports on the effect of sonication on SAz-1 and SWy-1 montmorillonite suspensions. Changes in the size of the particles of these materials and modifications of their properties have been investigated. The variation of the particle size has been analyzed by DLS (dynamic light scattering). In all cases the clay particles show a bimodal distribution. Sonication resulted in a decrease of the larger modal diameter, as well as a reduction of its volume percentage. Simultaneously, the proportion of the smallest particles increases. After 60 min of sonication, SAz-1 presented a very broad particle size distribution with a modal diameter of 283 nm. On the other hand, the SWy-1 sonicated for 60 min presents a bimodal distribution of particles at 140 and 454 nm. Changes in the properties of the clay suspensions due to sonication were evaluated spectroscopically from dye-clay interactions, using Methylene Blue. The acidic sites present in the interlamellar region, which are responsible for dye protonation, disappeared after sonication of the clay. The changes in the size of the scattering particles and the lack of acidic sites after sonication suggest that sonication induces delamination of the clay particles. PMID:18572177

  10. Interaction of polymer with discotic clay particles.

    SciTech Connect

    Auvray, L.; Lal, J.

    1999-08-04

    Normally synthetic well defined monodisperse discotic laponite clays are known to form a gel phase at mass concentrations as low as a few percent in distilled water. Hydrosoluble polymer polyethylene oxide was added to this intriguing clay system, it was observed that it either prevents gelation or slows it down extremely depending on the polymer weight, concentration or the laponite concentration. Small Angle Neutron scattering (SANS) was used to study these systems because only by isotopic labeling can the structure of the adsorbed polymer layers be determined. The contrast variation technique is specifically used to determine separately the different partial structure factors of the clay and polymer. In this way the signal of the adsorbed chains is separated from the signal of the free chains in the dilute regime. Attempts have also been made to characterize the structure in the concentrated regime of laponite with polymer.

  11. Fractal dimensions of flocs between clay particles and HAB organisms

    NASA Astrophysics Data System (ADS)

    Wang, Hongliang; Yu, Zhiming; Cao, Xihua; Song, Xiuxian

    2011-05-01

    The impact of harmful algal blooms (HABs) on public health and related economics have been increasing in many coastal regions of the world. Sedimentation of algal cells through flocculation with clay particles is a promising strategy for controlling HABs. Previous studies found that removal efficiency (RE) was influenced by many factors, including clay type and concentration, algal growth stage, and physiological aspects of HAB cells. To estimate the effect of morphological characteristics of the aggregates on HAB cell removal, fractal dimensions were measured and the RE of three species of HAB organism, Heterosigma akashiwo, Alexandrium tamarense, and Skeletonema costatum, by original clay and modified clay, was determined. For all HAB species, the modified clay had a higher RE than original clay. For the original clay, the two-dimensional fractal dimension ( D 2) was 1.92 and three-dimensional fractal dimension ( D 3) 2.81, while for the modified clay, D 2 was 1.84 and D 3 was 2.50. The addition of polyaluminum chloride (PACl) lead to a decrease of the repulsive barrier between clay particles, and resulted in lower D 2 and D 3. Due to the decrease of D 3, and the increase of the effective sticking coefficient, the flocculation rate between modified clay particles and HAB organisms increased, and thus resulted in a high RE. The fractal dimensions of flocs differed in HAB species with different cell morphologies. For example, Alexandrium tamarense cells are ellipsoidal, and the D 3 and D 2 of flocs were the highest, while for Skeletonema costatum, which has filamentous cells, the D 3 and D 2 of flocs were the lowest.

  12. Orientation of charged clay nanotubes in evaporating droplet meniscus.

    PubMed

    Zhao, Yafei; Cavallaro, Giuseppe; Lvov, Yuri

    2015-02-15

    During drying, an aqueous suspension of strongly charged halloysite clay nanotubes concentrates at the edge of the droplet ("coffee-ring" effect) which provides alignment of the tubes along the liquid-substrate contact line. First, the surface charge of the nanotubes was enhanced by polyanion adsorption inside of the lumen to compensate for the internal positive charges. This increased the magnitude of the ξ-potential of the tubes from -36 to -81 mV and stabilized the colloids. Then, colloidal halloysite was dropped onto the substrate, dried at 65 °C and after a concentration of ∼0.05 mg mL(-1) was reached, the alignment of nanotubes occurred starting from the droplet edges. The process was described with Onsager's theory, in which longer nanorods, which have higher surface charge, give better ordering after a critical concentration is reached. This study indicates a new application of halloysite clay nanotubes in polymeric composites with anisotropic properties, microchannel orientation, and production of coatings with aligned nanotubes. PMID:25460691

  13. Acoustic measurements of clay-size particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of sediment concentration is important in the study of streams and rivers. The work presented explores using high frequency (20 MHz) acoustic signal attenuation to measure the concentration of fine sediment particles (0.2-5.0 microns) in a fluvial environment. A small laboratory tank with...

  14. Magnetorheological behavior of magnetite covered clay particles in aqueous suspensions

    NASA Astrophysics Data System (ADS)

    Galindo-Gonzalez, C.; Lopez-Lopez, M. T.; Duran, J. D. G.

    2012-08-01

    Montmorillonite clay particles coated with magnetite nanoparticles suspended in aqueous media behave as magnetorheological fluids with enhanced stability as compared to conventional ones. In this work, the study of the magnetorheological behavior of these suspensions of magnetite-clay composite particles has been carried out. For this purpose, both steady and dynamic rheological measurements were carried out in the absence and in the presence of external magnetic fields. In the first kind of experiments, the rheograms of the suspensions (shear stress versus shear rate plot) are analyzed as a function of the strength of the magnetic field applied. In the second one, oscillatory stresses are applied to the system, and the storage modulus is studied as a function of the external magnetic field. In the absence of magnetic field, the suspensions develop a weak yield stress due to the aggregation of the magnetite covered clay particles. In the presence of magnetic field, the yield stress is strongly dependent on the magnetic field strength inside the samples, demonstrating that the suspensions experience a magnetorheological effect, moderate when the magnetic field strength is weak and stronger for values of magnetic field higher than 150-200 kA/m. Actually, the most intriguing result is the change of the trend in the dependence of the yield stress with the field. This dependence is approximately linear with the field for strength values smaller than 150-200 kA/m. On the other hand, for higher values, the yield stress increases with magnetic field following a power law with exponent 4.5.The results are interpreted by means of a model that relates the structure of the particles in the suspensions to the magnetic field applied and using the interaction energy between particles calculated by the extended DLVO theory to include magnetic interaction.

  15. Nano sized clay detected on chalk particle surfaces

    NASA Astrophysics Data System (ADS)

    Skovbjerg, L. L.; Hassenkam, T.; Makovicky, E.; Hem, C. P.; Yang, M.; Bovet, N.; Stipp, S. L. S.

    2012-12-01

    Chalk is a sedimentary rock consisting mostly of micrometer sized particles of biogenic calcite (CaCO3). It forms the reservoirs for oil in the Danish part of the North Sea and important drinking water aquifers in northern Europe. The interaction between organic molecules and the particle surfaces has a strong influence on the migration of oil in the reservoirs. Adhesion of oil components to chalk particle surfaces is thought to significantly reduce production and efforts are being made to determine the mechanisms behind enhanced/improved oil recovery (EOR/IOR) during water flooding. Aquifers beneath industrial areas can be heavily polluted with organic compounds and similar adsorption mechanisms could influence the geographical extent of the contaminant plume. Chalk, as a sedimentary rock, has been studied extensively for many years but the properties of the particle surfaces, where adsorption takes place, are largely unknown. In this study, we have used atomic force microscopy (AFM) to show that the grain surfaces in offshore and onshore chalk are more heterogeneous than previously assumed. The particles are not simply calcite surfaces but are partially covered by clay that is only 1-4 nm thick. With chemical force mapping (CFM), we have probed the surface using a tip coated with organic molecules to represent a tiny, mono-functionalized oil droplet. The functional groups of the self assembled monolayer on the tip were either -CH3 or -COO-. From maps of adhesion, it is evident that in calcite saturated water, both the polar and the nonpolar functional groups adhere to the nano sized clay particles but not to calcite. This is fundamentally important information for the development of conceptual and chemical models to explain wettability alterations in chalk reservoirs.

  16. Orientation specific deposition of mesoporous particles

    NASA Astrophysics Data System (ADS)

    Kjellman, Tomas; Bodén, Niklas; Wennerström, Hâkan; Edler, Karen J.; Alfredsson, Viveka

    2014-11-01

    We present a protocol for a facile orientation specific deposition of plate-like mesoporous SBA-15 silica particles onto a surface (mesopores oriented normal to surface). A drop of an aqueous dispersion of particles is placed on the surface and water vaporizes under controlled relative humidity. Three requirements are essential for uniform coverage: particle dispersion should not contain aggregates, a weak attraction between particles and surface is needed, and evaporation rate should be low. Aggregates are removed by stirring/sonication. Weak attraction is realized by introducing cationic groups to the surface. Insight into the mechanisms of the so-called coffee stain effect is also provided.

  17. Light scattering by randomly oriented spheroidal particles

    NASA Technical Reports Server (NTRS)

    Asano, S.; Sato, M.

    1980-01-01

    A study of the light scattering properties of randomly oriented, identical spheroidal particles is presented. A computation method was developed to integrate the Asano and Yamomoto solution (1975) for scattering from a homogeneous spheroid over all particle orientations; the extinction and scattering cross-sections, the asymmetry factor, and scattering matrix elements are calculated for randomly oriented prolate and oblate spheroids and compared with the calculations for spheres and laboratory measurements. The angular scattering behavior of spheroids is found to be different from that of the spheres for side scattering to backscattering directions, and prolate and oblate spheroids of the same shape parameter have similar angular scattering patterns.

  18. Modeling the arrangement of particles in natural swelling-clay porous media using three-dimensional packing of elliptic disks

    NASA Astrophysics Data System (ADS)

    Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J.; Levitz, Pierre

    2015-06-01

    Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997), 10.1103/PhysRevE.55.1959]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓa/ℓb less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.

  19. Pickering emulsions stabilized by paraffin wax and Laponite clay particles.

    PubMed

    Li, Caifu; Liu, Qian; Mei, Zhen; Wang, Jun; Xu, Jian; Sun, Dejun

    2009-08-01

    Emulsions containing wax in dispersed droplets stabilized by disc-like Laponite clay particles are prepared. Properties of the emulsions prepared at different temperatures are examined using stability, microscopy and droplet-size analysis. At low temperature, the wax crystals in the oil droplets can protrude through the interface, leading to droplet coalescence. But at higher temperatures, the droplet size decreases with wax concentration. Considering the viscosity of the oil phase and the interfacial tension, we conclude that the wax is liquid-like during the high temperature emulsification process, but during cooling wax crystals appear around the oil/water interface and stabilize the droplets. The oil/water ratio has minimal effect on the emulsions between ratios of 3:7 and 7:3. The Laponite is believed to stabilize the emulsions by increasing the viscosity of the continuous phase and also by adsorbing at the oil/water interface, thus providing a physical barrier to coalescence. PMID:19428022

  20. Freeze-agglomeration: An alternative mechanism for clay film formation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oriented clay coatings (argillans, clay cutans, clay films, lamellae) are often interpreted to be caused by illuviation (pervection, lessivage) of fine clay particles. In montane meadow soils (Typic Humaquepts) of the northern Sierra Nevada Range, prominent clay cutans occur on ped faces of a paleos...

  1. Probing the interface of microscopic clay particles in aqueous solution by second harmonic generation

    SciTech Connect

    Yan, E.C.Y.; Eisenthal, K.B.

    1999-07-22

    The abundance in nature and the unique adsorptive and catalytic properties of clay particles make them a subject of fundamental and technological interest. Clay particles have long been recognized as important catalysts in petroleum-forming reactions and in the chemical evolution of certain organic compounds related to the origin of life. The large surface area make them excellent adsorbents and is the basis for their increasing use to remove organic and inorganic environmental pollutants. Industries also use them in a number of applications, e.g., decolorizing agents, carriers for insecticides, and detergent formulation. Second harmonic generation (SHG) is applied for the first time to study the surfaces of clay particles. An SHG signal was detected from an aqueous suspension of disk-shaped montmorillonite clay particles of 0.5 {micro}m diameter and 0.01 {micro}m thickness. The origin of the SHG signal is the polarization of water molecules by surface charges located in the edge region of the clay particles. On addition of the organic molecule 4-(2-pyridylazo)resorcinol (PR) to the clay aqueous suspension, a strong SHG signal originating from the PR molecules adsorbed onto the edge surfaces of the clay particles was obtained. The PR adsorbed on the basal planes do not contribute to the SHG signal because of cancellation effects. These experimental results demonstrate the applicability of the SHG method for studying molecular adsorption and the electrostatic properties of clay particles.

  2. Cotransport of clay colloids and viruses through water-saturated vertically oriented columns packed with glass beads: Gravity effects.

    PubMed

    Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

    2016-03-01

    The cotransport of clay colloids and viruses in vertically oriented laboratory columns packed with glass beads was investigated. Bacteriophages MS2 and ΦX174 were used as model viruses, and kaolinite (ΚGa-1b) and montmorillonite (STx-1b) as model clay colloids. A steady flow rate of Q=1.5 mL/min was applied in both vertical up (VU) and vertical down (VD) flow directions. In the presence of KGa-1b, estimated mass recovery values for both viruses were higher for VD than VU flow direction, while in the presence of STx-1b the opposite was observed. However, for all cases examined, the produced mass of viruses attached onto suspended clay particles were higher for VD than VU flow direction, suggesting that the flow direction significantly influences virus attachment onto clays, as well as packed column retention of viruses attached onto suspended clays. KGa-1b hindered the transport of ΦX174 under VD flow, while STx-1b facilitated the transport of ΦX174 under both VU and VD flow directions. Moreover, KGa-1b and STx-1b facilitated the transport of MS2 in most of the cases examined except of the case where KGa-1b was present under VD flow. Also, the experimental data were used for the estimation of virus surface-coverages and virus surface concentrations generated by virus diffusion-limited attachment, as well as virus attachment due to sedimentation. Both sedimentation and diffusion limited virus attachment were higher for VD than VU flow, except the case of MS2 and STx-1b cotransport. The diffusion-limited attachment was higher for MS2 than ΦΧ174 for all cases examined. PMID:26747984

  3. The surface modification of clay particles by RF plasma technique

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Keol

    In this study, the surface coatings of ball clay, organoclay and exfoliated clay prepared by sol-gel process were done by RF plasma polymerization to improve the surface activity of the clay filler. Characterization of the above plasma-treated clays has been carried out by various techniques. The effects of plasma-treated clays as substitute of carbon black in styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer (EPDM) on the curing and mechanical properties were investigated. After plasma treatment, the tensile properties of organo and exfoliated clay were not unsatisfactory to that of carbon black filler system. Moreover, only 10 phr filler loading of plasma-treated organoclay in EPDM vulcanizates showed better results than 40 phr filler loading of carbon black in EPDM vulcanizates. The main objective of this study was to verify the applicability of the plasma technique for modifying clay surfaces for their use in the tire manufacturing industry. Another purpose was to reveal the advantage of the plasma technique used to obtain modified-clay and improved properties that those materials can display.

  4. Preferred Orientations and Anisotropy in Shales: Callovo-Oxfordian Shale (France) and Opalinus Clay (Switzerland)

    SciTech Connect

    Wenk, H.-R.; Voltolini, M.; Mazurek, M.; Van Loon, L.R.; Vinsot, A.

    2009-06-30

    Anisotropy in clay-rich sedimentary rocks is receiving increasing attention. Seismic anisotropy is essential in the prospecting for petroleum deposits. Anisotropy of diffusion has become relevant for environmental contaminants, including nuclear waste. In both cases, the orientation of component minerals is a critical ingredient and, largely because of small grain size and poor crystallinity, the orientation distribution of clay minerals has been difficult to quantify. A method is demonstrated that relies on hard synchrotron X-rays to obtain diffraction images of shales and applies the crystallographic Rietveld method to deconvolute the images and extract quantitative information about phase fractions and preferred orientation that can then be used to model macroscopic physical properties. The method is applied to shales from European studies which investigate the suitability of shales as potential nuclear waste repositories (Meuse/Haute-Marne Underground Research Laboratory near Bure, France, and Benken borehole and Mont Terri Rock Laboratory, Switzerland). A Callovo-Oxfordian shale from Meuse/Haute-Marne shows a relatively weak alignment of clay minerals and a random distribution for calcite. Opalinus shales from Benken and Mont Terri show strong alignment of illite-smectite, kaolinite, chlorite, and calcite. This intrinsic contribution to anisotropy is consistent with macroscopic physical properties where anisotropy is caused both by the orientation distribution of crystallites and high-aspect-ratio pores. Polycrystal elastic properties are obtained by averaging single crystal properties over the orientation distribution and polyphase properties by averaging over all phases. From elastic properties we obtain anisotropies for p waves ranging from 7 to 22%.

  5. Role of food and clay particles in toxicity of copper and diazinon using Daphnia magna.

    PubMed

    Jeon, Junho; Sung Ra, Jin; Lee, Sun Hong; Lee, Myun J; Yu, Seung H; Kim, Sang Don

    2010-03-01

    Toxicity changes in copper and diazinon were investigated in the presence of food, clay, and their mixture by using Daphnia magna. In sorption equilibrium experiments, copper was significantly attracted (>34% sorbed) to food, clay, and food-clay mixture due to their negative zeta potential, while diazinon was less sorbed (<11%). In the exposure test with food and clay particles, it was revealed that copper was remarkably reduced in the presence of clay particles indicating the change in bioavailability of copper by sorption to clay. This was considered as the primary mechanism for toxicity reduction whereas diazinon toxicity was food dependent in the analysis of toxicity using toxicity change index (TCI). It was also shown that certain foods could not only act as a sorbent to copper and diazinon, but also as a material of energy source to alleviate the toxic damage. Meanwhile, clay can be considered as a prominent sorbent to copper but not to diazinon and can inhibit the sorption interaction between foodstuffs and toxicants through the aggregation and sedimentation processes. Furthermore, clay particles, as shown in TCI analysis, may be a potentially risky material as a physiological stressor or a toxicant carrier in contaminated environments. PMID:19942290

  6. Orientation and Relaxation of Polymer-clay Solutions Studied by Rheology and Small-angle Neutron Scattering

    SciTech Connect

    Malwitz, M. M.; Butler, Paul D; Porcar, L.; Angelette, D. P.; Schmidt, G.

    2004-01-01

    The influence of shear on viscoelastic solutions of poly(ethylene oxide) (PEO) and clay [montmorillonite, i.e., Cloisite NA+ (CNA)] was investigated with rheology and small-angle neutron scattering (SANS). The steady-state viscosity and SANS were used to measure the shear-induced orientation and relaxation of the polymer and clay platelets. Anisotropic scattering patterns developed at much lower shear rates than in pure clay solutions. The scattering anisotropy saturated at low shear rates, and the CNA clay platelets aligned with the flow, with the surface normal parallel to the gradient direction. The cessation of shear led to partial and slow randomization of the CNA platelets, whereas extremely fast relaxation was observed for laponite (LRD) platelets. These PEO-CNA networklike solutions were compared with previously reported PEO-LRD networks, and the differences and similarities, with respect to the shear orientation, relaxation, and polymer-clay interactions, were examined.

  7. Fine particle clay catalysts for coal liquefaction. Quarterly technical report, May 9, 1991--August 8, 1991

    SciTech Connect

    Olson, E.S.

    1991-12-31

    The efficient production of environmentally acceptable distillate fuels requires catalysts for hydrogenation and cleavage of the coal macromolecules and removal of oxygen, nitrogen, and sulfur heteroatoms. The goal of the proposed research is to develop new catalysts for the direct liquefaction of coal. This type of catalyst consists of fine clay particles that have been treated with reagents which form pillaring structures between the aluminosilicate layers of the clay. The pillars not only hold the layers apart but also constitute the active catalytic sites for hydrogenation of the coal and the solvent used in the liquefaction. The pillaring catalytic sites are composed of pyrrhotite, which has been previously demonstrated to be active for coal liquefaction. The pyrrhotite sites are generated in situ by sulfiding the corresponding oxyiron species. The size of the catalyst will be less than 40 nm in order to promote intimate contact with the coal material. Since the clays and reagents for pillaring and activating the clays are inexpensive, the catalysts can be discarded after use, rather than regenerated by a costly process. The proposed work will evaluate methods for preparing the fine particle iron-pillared clay dispersions and for activating the particles to generate the catalysts. Characterization studies of the pillared clays and activated catalysts will be performed. The effectiveness of the pillared clay dispersion for hydrogenation and coal liquefaction will be determined in several types of testing.

  8. Fine particle clay catalysts for coal liquefaction. Final technical report

    SciTech Connect

    Olson, E.S.

    1995-08-01

    In an effort to develop new disposable catalysts for direct coal liquefaction, several types of clay-supported pyrrhotite catalysts were prepared and tested. These included iron-pillared montmorillonite, mixed iron/alumina-pillared montmorillonite, iron-impregnated montmorillonite, and iron oxometallate-impregnated montmorillonite.

  9. Influence of clay particles on the transport and retention of titanium dioxide nanoparticles in quartz sand.

    PubMed

    Cai, Li; Tong, Meiping; Wang, Xueting; Kim, Hyunjung

    2014-07-01

    This study investigated the influence of two representative suspended clay particles, bentonite and kaolinite, on the transport of titanium dioxide nanoparticles (nTiO2) in saturated quartz sand in both NaCl (1 and 10 mM ionic strength) and CaCl2 solutions (0.1 and 1 mM ionic strength) at pH 7. The breakthrough curves of nTiO2 with bentonite or kaolinite were higher than those without the presence of clay particles in NaCl solutions, indicating that both types of clay particles increased nTiO2 transport in NaCl solutions. Moreover, the enhancement of nTiO2 transport was more significant when bentonite was present in nTiO2 suspensions relative to kaolinite. Similar to NaCl solutions, in CaCl2 solutions, the breakthrough curves of nTiO2 with bentonite were also higher than those without clay particles, while the breakthrough curves of nTiO2 with kaolinite were lower than those without clay particles. Clearly, in CaCl2 solutions, the presence of bentonite in suspensions increased nTiO2 transport, whereas, kaolinite decreased nTiO2 transport in quartz sand. The attachment of nTiO2 onto clay particles (both bentonite and kaolinite) were observed under all experimental conditions. The increased transport of nTiO2 in most experimental conditions (except for kaolinite in CaCl2 solutions) was attributed mainly to the clay-facilitated nTiO2 transport. The straining of larger nTiO2-kaolinite clusters yet contributed to the decreased transport (enhanced retention) of nTiO2 in divalent CaCl2 solutions when kaolinite particles were copresent in suspensions. PMID:24911544

  10. Phase diagrams of Wyoming Na-montmorillonite clay. Influence of particle anisotropy.

    PubMed

    Michot, Laurent J; Bihannic, Isabelle; Porsch, Katharina; Maddi, Solange; Baravian, Christophe; Mougel, Julien; Levitz, Pierre

    2004-12-01

    Natural Na-Wyoming montmorillonite was size fractionated by successive centrifugation. Polydisperse particles with average sizes of 400, 290, and 75 nm were then obtained. As the structural charge of the particles belonging to three fractions (determined by cationic exchange capacity measurements) is the same, such a procedure allows studying the effect of particle anisotropy on the colloidal phase behavior of swelling clay particles. Osmotic stress experiments were carried out at different ionic strengths. The osmotic pressure curves display a plateau whose beginning systematically coincides with the sol/gel transition determined by oscillatory stress measurements. The concentration corresponding to the sol/gel transition increases linearly with particle anisotropy, which shows that the sol/gel transition is not directly related to an isotropic/nematic transition of individual clay particles. Indeed, a reverse evolution should be observed for an I/N transition involving the individual clay particles. Still, when observed between crossed polarizer and analyzer, the gel samples exhibit permanent birefringent textures, whereas in the "sol" region, transient birefringence is observed when the samples are sheared. This suggests that interacting clay particles are amenable to generate, at rest and/or under shear, large anisotropic particle associations. PMID:15568830

  11. Cotransport of viruses and clay particles in water saturated and unsaturated porous media

    NASA Astrophysics Data System (ADS)

    Chrysikopoulos, C. V.; Syngouna, V. I.

    2014-12-01

    This experimental study examines the effects of clay colloids on the transport of viruses in variably saturated porous media. All cotransport experiments were conducted in both saturated and partially saturated columns packed with glass beads, using bacteriophages MS2 and ΦΧ174 as model viruses, and kaolinite (KGa-1b) and montmorillonite (STx-1b) as model clay colloids. The various experimental collision efficiencies were determined using the classical colloid filtration theory. The experimental data indicated that the mass recovery of viruses and clay colloids decreased as the water saturation decreased. Temporal moments of the various breakthrough concentrations collected, suggested that the presence of clays significantly influenced virus transport and irreversible deposition onto glass beads. The mass recovery of both viruses, based on total effluent virus concentrations, was shown to reduce in the presence of suspended clay particles. Furthermore, the transport of suspended virus and clay-virus particles was retarded, compared to the conservative tracer. Under unsaturated conditions both clay particles hindered the transport of the two viruses considered in this work. Moreover, the surface properties of viruses, clays and glass beads were employed for the construction of classical DLVO and capillary potential energy profiles, and the results suggested that capillary forces play a significant role on colloid retention. It was estimated that the capillary potential energy of MS2 is lower than that of ΦΧ174, and the capillary potential energy ofKGa-1b is lower than that of STx-1b, assuming that the protrusion distance through the water filmis the same for each pair of particles. Moreover, the capillary potential energy is several orders of magnitude greater than the DLVO energy potential. Figure 1Schematic illustration of the various concentrations involved in the cotransport experiments for: (a) saturated and (b) unsaturated porous media.

  12. Synthesis of polymer latex particles decorated with organically-modified laponite clay platelets via emulsion polymerization.

    PubMed

    Herrera, Norma Negrete; Persoz, Stéphanie; Putaux, Jean-Luc; David, Laurent; Bourgeat-Lami, Elodie

    2006-02-01

    We report a new route to colloidal nanocomposites consisting of polymer latex particles covered with Laponite clay nanoplatelets. These composite particles are prepared by seeded emulsion (co)polymerization of styrene and butyl acrylate from Laponite clay suspensions previously functionalized by ion exchange using either a free radical initiator: 2,2-azobis (2-methylpropionamidine) hydrochloride (AIBA) or a cationic vinyl monomer: 2-(methacryloyloxy) ethyl trimethyl ammonium chloride (MADQUAT). The successful intercalation of the cationic reactive molecules was confirmed by elemental analysis, FTIR, 13C solid-state NMR and WAXD. The organically-modified clays were dispersed into water with the help of tetrasodium pyrophosphate and an anionic surfactant. stable latexes, produced under different experimental conditions, were successfully obtained from the clay suspensions. Cryo-TEM images of the resulting latexes showed spherical composite particles with diameters in the 50-250 nm range with clay sheets located on their surface. This paper reports on the effect of the processing conditions on the particle morphology and latex stability, and describes the mechanism of formation of the nanocomposite particles. PMID:16573041

  13. Desorption of intrinsic cesium from smectite: inhibitive effects of clay particle organization on cesium desorption.

    PubMed

    Fukushi, Keisuke; Sakai, Haruka; Itono, Taeko; Tamura, Akihiro; Arai, Shoji

    2014-09-16

    Fine clay particles have functioned as transport media for radiocesium in terrestrial environments after nuclear accidents. Because radiocesium is expected to be retained in clay minerals by a cation-exchange reaction, ascertaining trace cesium desorption behavior in response to changing solution conditions is crucially important. This study systematically investigated the desorption behavior of intrinsic Cs (13 nmol/g) in well-characterized Na-montmorillonite in electrolyte solutions (NaCl, KCl, CaCl2, and MgCl2) under widely differing cation concentrations (0.2 mM to 0.2 M). Batch desorption experiments demonstrated that Cs(+) desorption was inhibited significantly in the presence of the environmental relevant concentrations of Ca(2+) and Mg(2+) (>0.5 mM) and high concentrations of K(+). The order of ability for Cs desorption was Na(+) = K(+) > Ca(2+) = Mg(2+) at the highest cation concentration (0.2 M), which is opposite to the theoretical prediction based on the cation-exchange selectivity. Laser diffraction grain-size analyses revealed that the inhibition of Cs(+) desorption coincided with the increase of the clay tactoid size. Results suggest that radiocesium in the dispersed fine clay particles adheres on the solid phase when the organization of swelling clay particles occurs because of changes in solution conditions caused by both natural processes and artificial treatments. PMID:25144123

  14. Surface characteristics and photoactivity of silver-modified palygorskite clays coated with nanosized titanium dioxide particles

    SciTech Connect

    Zhao Difang . E-mail: zdf6910@163.com; Zhou Jie; Liu Ning

    2007-03-15

    This paper presents the results of a study in which nanosized titanium dioxide (TiO{sub 2}) crystal particles were coated onto the surface of palygorskite fibrous clay which had been modified by silver ions using titanium tetrachloride as a precursor. Coated TiO{sub 2} particles with the anatase structure were formed after calcining at 400 deg. C for 2 h in air. Various analytical techniques were used to characterize the surface properties of titanium dioxide particles on the palygorskite. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that TiO{sub 2} particles were supported on the surface of the palygorskite clays and their size was in the range of 3-6 nm. The titanium oxide coatings were found to be very active for the photocatalytic decomposition of methylene blue.

  15. Improved dewatering behavior of clay minerals dispersions via interfacial chemistry and particle interactions optimization.

    PubMed

    McFarlane, Angus; Bremmell, Kristen; Addai-Mensah, Jonas

    2006-01-01

    Orthokinetic flocculation of clay dispersions at pH 7.5 and 22 degrees C has been investigated to determine the influence of interfacial chemistry and shear on dewatering and particle interactions behavior. Modification of pulp chemistry and behavior was achieved by using kaolinite and Na-exchanged (swelling) smectite clay minerals, divalent metal ions (Ca(II), Mn(II)) as coagulants and anionic polyacrylamide copolymer (PAM A) and non-ionic polyacrylamide homopolymer (PAM N) as flocculants. The pivotal role of shear, provided by a two-blade paddle impeller, was probed as a function of agitation rate (100-500 rpm) and time (15/60 s). Particle zeta potential and adsorption isotherms were measured to quantify the interfacial chemistry, whilst rheology and cryogenic SEM were used to investigate particle interactions and floc structure and aggregate network, respectively. Osmotic swelling, accompanied by the formation of "honeycomb" particle network structure and high yield stress, was produced by the Na-exchanged smectite, but not kaolinite, dispersions. Dispersion of the clay particles in 0.05 M Ca(II) or Mn(II) solution led to a marked reduction in particle zeta potential, complete suppression of swelling, honeycomb network structure collapse and a concomitant reduction in shear yield stress of smectite pulps. Optimum conditions for improved, orthokinetic flocculation performance of negatively charged clay particles, reflecting faster settling flocs comprised (i) coagulation, (ii) moderate agitation rate, (iii) shorter agitation time, and (iv) anionic rather than non-ionic PAM. The optimum dewatering rates were significantly higher than those produced by standard, manual-mixing flocculation techniques (plunging and cylinder inversion) commonly used in industry for flocculant trials. The optimum flocculation conditions did not, however, have a significant impact on the final sediment solid content of 20-22 wt%. Further application of shear to pre-sedimented pulps

  16. Influence of clay particles on microfluidic-based preparation of hydrogel composite microsphere

    NASA Astrophysics Data System (ADS)

    Hong, Joung Sook

    2016-05-01

    For the successful fabrication of a hydrogel composite microsphere, this study aimed to investigate the influence of clay particles on microsphere formation in a microfluidic device which has flow focusing and a 4.5:1 contraction channel. A poly alginic acid solution (2.0 wt.%) with clay particles was used as the dispersed phase to generate drops in an oil medium, which then merged with drops of a CaCl2 solution for gelation. Drop generations were observed with different flow rates and particles types. When the flow rate increased, drop generation was enhanced and drop size decreased by the build-up of more favorable hydrodynamic flow conditions to detach the droplets. The addition of a small amount of particles insignificantly changed the drop generation behavior even though it reduced interfacial tension and increased the viscosity of the solution. Instead, clays particles significantly affected hydro-gelation depending on the hydrophobicity of particles, which produced further heterogeneity in the shape and size of microsphere.

  17. Influence of the layer charge and clay particle size on the interactions between the cationic dye methylene blue and clays in an aqueous suspension.

    PubMed

    Neumann, Miguel G; Gessner, Fergus; Schmitt, Carla C; Sartori, Rogerio

    2002-11-15

    The spectroscopic behavior of the dye MB in suspensions of different clays have been used for evaluating layer charge density influence on the adsorption properties of the particles. The clays with higher charge density, like SAz-1 and SCa-3, promote a higher aggregation and do not show deaggregation at longer times, so that practically only the aggregate peak at approximately 570 nm is observed, without any change with time. This is due to, on one side, the larger particle size that decreases the surface area available for adsorption. Additionally, the clay layers will be held together more tightly, avoiding the migration of the dye to the interlamellar region. On the other hand, SWy-1, having a lower charge density, shows a completely different behavior. The dye molecules, initially adsorbed as aggregates on the outer surface of the clay, deaggregate to form monomers that migrate to the interlamellar spaces, giving rise to absorption bands at 670 and 760 nm. Experiments using Ca-exchanged SWy-1, variation of the ionic strength by addition of salt, and the use of different size fractions of the clays confirm the finding that the main factor ruling the adsorption behavior of the probe is the size of the clay particles. PMID:12505071

  18. Calcination of kaolinite clay particles for cement production: A modeling study

    SciTech Connect

    Teklay, Abraham; Yin, Chungen; Rosendahl, Lasse; Bøjer, Martin

    2014-07-01

    Kaolinite rich clay particles calcined under certain conditions can attain favorable pozzolanic properties and can be used to substitute part of the CO{sub 2} intensive clinker in cement production. To better guide calcination of a clay material, a transient one-dimensional single particle model is developed, which fully addresses the conversion process of raw kaolinite particles suspended in hot gas. Particles are discretized into a number of spherical cells, on each of which mass, momentum, energy and species conservation equations are numerically solved by using the finite volume method. Reactions considered in the model include dehydration, dehydroxylation and various phase transformations. Thermogravimetric analysis is used to determine reaction kinetic data required as inputs in the model and to validate the model. Finally, model-based sensitivity analysis is performed, from which quantitative guidelines for calcination condition optimization are derived. - Highlights: • A general 1D mathematical model for single clay particle calcination is developed. • The model fully addresses momentum, heat and mass transfer and all the reactions. • Experiments are performed to determine kinetic data of the key reactions. • The model is verified by different means, including experimental results. • Sensitivity study is done to address key assumptions and derive useful guidelines.

  19. Crystallography of decahedral and icosahedral particles. II - High symmetry orientations

    NASA Technical Reports Server (NTRS)

    Yang, C. Y.; Yacaman, M. J.; Heinemann, K.

    1979-01-01

    Based on the exact crystal structure of decahedral and icosahedral particles, high energy electron diffraction patterns and image profiles have been derived for various high symmetry orientations of the particles with respect to the incident beam. These results form a basis for the identification of small metal particle structures with advanced methods of transmission electron microscopy.

  20. Flocculation and particle size analysis of expansive clay sediments affected by biological, chemical, and hydrodynamic factors

    NASA Astrophysics Data System (ADS)

    Tan, Xiaoling; Hu, Liming; Reed, Allen H.; Furukawa, Yoko; Zhang, Guoping

    2014-01-01

    Expansive clay sediments are abundant in riverine and estuarine waters and bottom beds, and their particle size distributions (PSD) are important for the analysis of sediment transport. This paper presents an experimental study to evaluate, using a laser particle size analyzer under varying flow conditions, the intrinsic PSD of two expansive clays, a Ca- and a Na-montmorillonite and the influence of biological, chemical, and hydrodynamic factors on their flocculation and PSD. The considered biological factor consists of three extracellular polymeric substances of varying polarity, including xanthan gum, guar gum, and chitosan; the chemical factor is the salinity; and the hydrodynamic factor is the types of flow indicated by the Reynolds number and shear rate. The intrinsic PSD of both clays show a multimodal lognormal distribution with sizes ranging from 0.2 to 50 μm. All three biopolymers, xanthan gum, guar gum, and chitosan, can facilitate flocculation through long-range polymer bridging and short-range ion-dipole interaction, hydrogen bonding, and Coulomb force. The influence of salinity is different for the two clays: the particle size of the Na-montmorillonite increases with salinity, which is caused by flocculation resulting from the suppressed electrical double layer, while that of the Ca-montmorillonite is slightly reduced owing to the decreased basal spacing and cation exchange. For different hydrodynamic conditions, higher shear rate promotes the flocculation of Ca-montmorillonite, but breaks the Na-montmorillonite flocs. The significance of understanding the flocculation and PSD of expansive clays is also discussed in terms of sediment transport under different aquatic environments.

  1. A recommended procedure for the preparation of oriented clay-mineral specimens for X-ray diffraction analysis; modifications to Drever's filter-membrane peel technique

    USGS Publications Warehouse

    Pollastro, R.M.

    1982-01-01

    Extremely well-oriented clay mineral mounts for X-ray diffraction analysis can be prepared quickly and without introducing segregation using the filter-membrane peel technique. Mounting problems encountered with smectite-rich samples can be resolved by using minimal sample and partial air-drying of the clay film before transfer to a glass slide. Samples containing small quantities of clay can produce useful oriented specimens if Teflon masks having more restrictive areas are inserted above the membrane filter during clay deposition. War]page and thermal shock of glass slides can be controlled by using a flat, porous, ceramic plate as a holding surface during heat treatments.

  2. Spatial confinement governs orientational order in patchy particles

    NASA Astrophysics Data System (ADS)

    Iwashita, Yasutaka; Kimura, Yasuyuki

    2016-06-01

    Orientational order in condensed matter plays a key role in determining material properties such as ferromagnetism, viscoelasticity or birefringence. We studied purely orientational ordering in closely-packed one-patch colloidal particles confined between flat substrates, where the particles can only rotate and are ordered via the sticky interaction between the patches. For the first time, we experimentally realized a rich variety of mesoscopic patterns through orientational ordering of colloids by controlling patch size and confinement thickness. The combination of experiment and numerical simulation reveals the decisive role of confinement: An ordered state(s) is selected from the (meta)stable options in bulk when it is commensurate with the system geometry and boundary conditions; otherwise, frustration induces a unique order. Our study offers a new means of systematic control over mesoscopic structures via orientational ordering in patchy particles. The system would also possess unique functionalities through the rotational response of the particles to external stimuli.

  3. Spatial confinement governs orientational order in patchy particles

    PubMed Central

    Iwashita, Yasutaka; Kimura, Yasuyuki

    2016-01-01

    Orientational order in condensed matter plays a key role in determining material properties such as ferromagnetism, viscoelasticity or birefringence. We studied purely orientational ordering in closely-packed one-patch colloidal particles confined between flat substrates, where the particles can only rotate and are ordered via the sticky interaction between the patches. For the first time, we experimentally realized a rich variety of mesoscopic patterns through orientational ordering of colloids by controlling patch size and confinement thickness. The combination of experiment and numerical simulation reveals the decisive role of confinement: An ordered state(s) is selected from the (meta)stable options in bulk when it is commensurate with the system geometry and boundary conditions; otherwise, frustration induces a unique order. Our study offers a new means of systematic control over mesoscopic structures via orientational ordering in patchy particles. The system would also possess unique functionalities through the rotational response of the particles to external stimuli. PMID:27264521

  4. Zeta potential of clay-size particles in urban rainfall runoff during hydrologic transport

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Yeop; Sansalone, John J.

    2008-07-01

    SummaryUrban rainfall-runoff transports a wide spectrum of anthropogenic aqueous complexes and particulate matter (PM). Zeta potential (ξ) as an electrostatic parameter provides an index of destabilization for clay-size particles (<2 μm) transported during hydrologic processes including passage of the runoff hydrograph. However, ξ of PM in urban rainfall-runoff has rarely been studied due to the dynamic and complex hydrologic, physical and chemical nature of rainfall-runoff systems. This study examined a series of rainfall-runoff events captured from a paved source area catchment in Baton Rouge, LA to characterize ξ of clay-size particles. The ξ of clay-size particles was also examined as a function of hydrologic transport with coupled water chemistry variables. Study results indicated that ξ varied from approximately -15 to -30 mV across the hydrograph of each event and generally mimicked the runoff intensity during hydrologic transport. Hydrologic transport results indicate while ξ was inversely correlated to the hydrograph flow rate, this inverse correlation was a function of variations in water chemistry parameters (pH and ionic strength); parameters that were driven by hydrologic flow rate. For each event ξ exhibited hysteretic trends as a function of rainfall-runoff ionic strength and pH during the passage of the hydrograph. Results demonstrate that hydrologic transport played an important role driving both water chemistry and ξ trends for clay-size particles; as well as treatment behavior of rainfall-runoff unit operations and processes.

  5. Orientational energy of anisometric particles in liquid-crystalline suspensions

    NASA Astrophysics Data System (ADS)

    Burylov, S. V.; Zakhlevnykh, A. N.

    2013-07-01

    We obtain a general expression for the orientational energy of an individual anisometric particle suspended in uniform nematic liquid crystals when the main axis of the particle rotates with respect to the nematic director. We show that there is a qualitative and quantitative analogy between the internal and external problems for cylindrical volumes of nematic liquid crystals, and on this basis we obtain an estimate of the orientational energy of a particle of cylindrical (rodlike, needlelike, or ellipsoidal) shape. For an ensemble of such particles we propose a modified form of their orientational energy in the nematic matrix. This orientational energy has the usual second-order term, and additional fourth-order term in the scalar product of the nematic director and the vector which characterizes an average direction of the main axes of the particles. As an example we obtain the expression for the free energy density of ferronematics, i.e., colloidal suspensions of needlelike magnetic particles in nematic liquid crystals. Unlike previous models, the free energy density includes the proposed modified form of the particle orientational energy, and also a contribution describing the surface saddle-splay deformations of the liquid crystal matrix.

  6. Benthic biofilm structure controls the deposition-resuspension dynamics of fine clay particles

    NASA Astrophysics Data System (ADS)

    Hunter, W. R.; Roche, K. R.; Drummond, J. D.; Boano, F.; Packman, A. I.; Battin, T. J.

    2015-12-01

    In fluvial ecosystems the alternation of deposition and resuspension of particles represents an important pathway for the downstream translocation of microbes and organic matter. Such particles can originate from algae and microbes, the spontaneous auto-aggregation of organic macromolecules (e.g., "river sown"), terrestrial detritus (traditionally classified as "particulate organic matter"), and erosive mineral and organo-mineral particles. The transport and retention of particles in headwater streams is associated with biofilms, which are surface-attached microbial communities. Whilst biofilm-particle interactions have been studied in bulk, a mechanistic understanding of these processes is lacking. Parallel macroscale/microscale observations are required to unravel the complex feedbacks between biofilm structure, coverage and the dynamics of deposition and resuspension. We used recirculating flume mesocosms to test how changes in biofilm structure affected the deposition and resuspension of clay-sized (< 10 μm) particles. Biofilms were grown in replicate 3-m-long recirculating flumes over variable lengths of time (0, 14, 21, 28, and 35) days. Fixed doses of fluorescent clay-sized particles were introduced to each flume and their deposition was traced over 30 minutes. A flood event was then simulated via a step increase in flowrate to quantify particle resuspension. 3D Optical Coherence Tomography was used to determine roughness, areal coverage and height of biofilms in each flume. From these measurements we characterised particle deposition and resuspension rates, using continuous time random walk modelling techniques, which we then tested as responses to changes in biofilm coverage and structure under both base-flow and flood-flow scenarios. Our results suggest that biofilm structural complexity is a primary control upon the retention and downstream transport of fine particles in stream mesocosms.

  7. Orientation and optical properties of methylene blue crystal for better understanding of interactions with clay mineral surface

    NASA Astrophysics Data System (ADS)

    Milošević, Maja; Logar, Mihovil

    2013-04-01

    The properties of cationic dye Methylene blue (MB) adsorbed on diferent surfaces have been investigated intensively over the years and various models for the orientation of its cations have been proposed (Hang and Brindley, 1970; Bujdak et al., 2003; Li and Zare, 2004; Marr III et al., 1973; Bujdak, 2006).The main objective of this work is to investigate and determine orientation and optical properties of metylene blue crystal upon its crystallization on a glass slate and to use those findings in better understanding of interactions with clay minerals. Cationic dyes have very high affinity for clay surfaces and those interactions are easily detected, therefore these dyes are used to determine several properties of clay surfaces (morphology, layer charge, CEC). For this study, we have selected a group of MB crystal and carried out XRD analysis, polarized absorption spectra measurement (400 - 900 nm) and determination of optical properties (pleochroism, determination of twining and extinction angle) using polarizing microscope. Methylene blue crystals are exhibiting mostly needle like habitus with huge difference in width - length ratio. According to X-ray diffraction it is quite obvious that the y (b) axis is perpendicular to the crystal surface. The x (a) and z (c) axis lie in the crystal plane (010). Crystals exhibit prominent dichroism: from blue (E || elong.) to colorless. In accordance with current interpretation of MB spectra peaks at 647 and 570 nm can be assigned as dimer aggregation and peaks at 475 and 406 nm as higher level of aggregation. All of them exhibit pronounced polarization dependence. The group of peaks at lower energy (700 to 900 nm) do not show significant polarization dependence and they correspond to the J - aggregates. Peak at around 800 nm have been noticed as fluorescence active. In dependence with thickness of the crystals and vibration direction we have observed presence of polysynthetic twinning which can be compared with polysynthetic

  8. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

    PubMed

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

    2009-09-28

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which

  9. Orientational defects near colloidal particles in a nematic liquid crystal.

    PubMed

    Feng, James J; Zhou, Chixing

    2004-01-01

    We study the interaction between a surface-anchoring colloidal particle and a liquid-crystalline host, and in particular the formation of orientational defects near the particle. A mean-field theory based on the nonlocal Marrucci-Greco nematic potential is used to represent molecular interactions in an inhomogeneous orientational field. An evolution equation for the molecular configuration tensor is solved numerically whose steady state minimizes the total free energy of the system. With strong homeotropic anchoring on the particle surface, three types of solutions may appear depending on initial conditions and particle size: Saturn rings, satellite point defects, and polar rings. The Saturn ring remains stable on micrometer-sized particles, contrary to previous calculations but consistent with experiments. A phase diagram is constructed for the three regimes. Based on the free energy, the most stable state is the Saturn ring for smaller particles and the satellite defect for larger ones. PMID:14651897

  10. Clay Chemistry's Influence on the Average Carbon Content and Particle Size at the Ninety-Six Historical Site, South Carolina

    NASA Astrophysics Data System (ADS)

    Lintz, L.; Werts, S. P.

    2014-12-01

    The Ninety-Six National Historic Site is located in Greenwood County, SC. Recent geologic mapping of this area has revealed differences in soil properties over short distances within the park. We studied the chemistry of the clay minerals found within the soils to see if there was a correlation between the amounts of soil organic carbon contained in the soil and particle size in individual soil horizons. Three different vegetation areas, including an old field, a deciduous forest, and a pine forest were selected to see what influence vegetation type had on the clay chemistry and carbon levels as well. Four samples containing the O, A, and B horizons were taken from each location and we studied the carbon and nitrogen content using an elemental analyzer, particle size using a Laser Diffraction Particle Size Analyzer, and clay mineralogy with powder X-ray diffraction of each soil sample. Samples from the old field and pine forest gave an overall negative correlation between carbon content and clay percentage, which is against the normal trend for Southern Piedmont Ultisols. The deciduous forest samples gave no correlation at all between its carbon content and clay percentage. Together, all three locations show the same negative relationship, while once separated into vegetation type and A and B horizons it shows even more abnormal relationships of negative while several show no correlation (R2= 0.007403- 0.56268). Using powder XRD, we ran clay samples from each A and B horizon for the clay mineralogy. All three vegetation areas had the same results of containing quartz, kaolinite, and Fe oxides, therefore, clay chemistry is not a reason behind the abnormal trend of a negative correlation between average carbon content and clay percentage. Considering that all three locations have the same climate, topography, and parent material of metagranite, it could be reasonable to assume these results are a factor of environmental and biological influences rather than clay type.

  11. Deciphering the science behind electrocoagulation to remove suspended clay particles from water.

    PubMed

    Holt, P K; Barton, G W; Mitchell, C A

    2004-01-01

    Electrocoagulation removes pollutant material from water by a combination of coagulant delivered from a sacrificial aluminium anode and hydrogen bubbles evolved at an inert cathode. Rates of clay particle flotation and settling were experimentally determined in a 7 L batch reactor over a range of currents (0.25-2.0 A) and pollutant loadings (0.1-1.7 g/L). Sedimentation and flotation are the dominant removal mechanism at low and high currents, respectively. This shift in separation mode can be explained by analysing the reactor in terms of a published dissolved air flotation model. PMID:15686019

  12. DNA-labeled clay: A sensitive new method for tracing particle transport

    USGS Publications Warehouse

    Mahler, B.J.; Winkler, M.; Bennett, P.; Hillis, D.M.

    1998-01-01

    The behavior of mobile colloids and sediment in most natural environments remains poorly understood, in part because characteristics of existing sediment tracers limit their wide-spread use. Here we describe the development of a new approach that uses a DNA-labeled montmorillonite clay as a highly sensitive and selective sediment tracer that can potentially characterize sediment and colloid transport in a wide variety of environments, including marine, wetland, ground-water, and atmospheric systems. Characteristics of DNA in natural systems render it unsuitable as an aqueous tracer but admirably suited as a label for tracing particulates. The DNA-labeled-clay approach, using techniques developed from molecular biology, has extremely low detection limits, very specific detection, and a virtually infinite number of tracer signatures. Furthermore, DNA-labeled clay has the same physical characteristics as the particles it is designed to trace, it is environmentally benign, and it can be relatively inexpensively produced and detected. Our initial results show that short (500 base pair) strands of synthetically produced DNA reversibly adsorb to both Na-montmorillonite and powdered silica surfaces via a magnesium bridge. The DNA-montmorillonite surface complexes are stable in calcium-bicarbonate spring waters for periods of up to 18 days and only slowly desorb to the aqueous phase, whereas the silica surface complex is stable only in distilled water. Both materials readily release the adsorbed DNA in dilute EDTA solutions for amplification by the polymerase chain reaction (PCR) and quantification. The stability of the DNA-labeled clay complex suggests that this material would be appropriate for use as an extremely sensitive sediment tracer for flow periods of as long as 2 weeks, and possibly longer.

  13. Janus-Particles in a rarefied gas: thermophoresis and orientation

    NASA Astrophysics Data System (ADS)

    Baier, Tobias; Shrestha, Samir; Tiwari, Sudarshan; Hardt, Steffen; Klar, Axel

    2015-11-01

    Thermophoresis, the motion of a particle along a thermal gradient, has been used both for preventing and inducing the deposition of aerosols on heated or cooled surfaces. In the latter case it may be advantageous to induce the deposition with a preferred orientation of the particle, for example by utilizing non-uniform reflective properties on the particle surface. As a model system we investigate a spherical Janus particle on which gas molecules are reflected diffusively from one hemisphere and specularly from the other. In the limit of large Knudsen number this is studied analytically, focusing on the interplay between thermophoretic motion and alignment of the particle. Without motion, a torque orients the particle with its diffuse side towards the colder gas. However, any motion of the particle relative to the gas results in a preferred alignment with the specular side in direction of the particle velocity. Thus the thermophoretic motion, which is towards the colder side, results in a weakening of the particle alignment. The results are supported by Monte-Carlo simulations to extend the range of validity towards finite Knudsen numbers. These findings shed light on the efficiency of aligned deposition of nanoparticles from a gas stream on a cooled surface.

  14. Electron paramagnetic resonance study of partially oriented clay platelets intercalated with copper(II) 1,4,8,11-tetraazacyclotetradecane.

    PubMed

    So, Hyunsoo; Jung, Hyun; Choy, Jin-Ho; Belford, R Linn

    2005-03-01

    Electron paramagnetic resonance (EPR) spectra of powder and oriented films of montmorillonite, hectorite, and saponite intercalated with [Cu(cyclam)](2+) (cyclam = 1,4,8,11-tetraazacyclotetradecane) exhibit three components: an orientation-dependent component without hyperfine features, an orientation-dependent component with hyperfine features, and an orientation-independent component without hyperfine feature. EPR spectra of [Cu(cyclam)](2+)-saponite, which exhibit only two components and the best resolved hyperfine features, were simulated. The spectra indicate that a large portion of the saponite platelets are inclined to the glass surface, although they tend to align with their basal planes parallel to the glass surface. The orientation-dependent spectra could be simulated by introducing a Gaussian distribution with a standard deviation of 20 degrees for the inclination angle. The standard deviation may be used as a disorder parameter for the microcrystals assembled on glass plates. Spectral simulation also shows that the CuN(4) plane of [Cu(cyclam)](2+) is parallel to the clay layers. EPR spectra of some other partially oriented systems are also discussed. PMID:16851360

  15. Single Particle Orientation and Rotational Tracking (SPORT) in biopysical studies

    SciTech Connect

    Gu, Yan; Ha, Ji Won; Augspurger, Ashley E.; Chen, Kuangcai; Zhu, Shaobin; Fang, Ning

    2013-08-02

    The single particle orientation and rotational tracking (SPORT) techniques have seen rapid development in the past 5 years. Recent technical advances have greatly expanded the applicability of SPORT in biophysical studies. In this feature article, we survey the current development of SPORT and discuss its potential applications in biophysics, including cellular membrane processes and intracellular transport.

  16. Characterization and Safety of Uniform Particle Size NovaSil Clay as a Potential Aflatoxin Enterosorbent

    PubMed Central

    Marroquín-Cardona, A.; Deng, Y.; Garcia-Mazcorro, J.; Johnson, N.M.; Mitchell, N.; Tang, L.; Robinson, A.; Taylor, J.; Wang, J.-S.; Phillips, T.D.

    2011-01-01

    NovaSil (NS) clay, a common anti-caking agent in animal feeds, has been shown to adsorb aflatoxins and diminish their bioavailability in multiple animal models. The safety of long-term dietary exposure to NS has also been demonstrated in a 6-month sub-chronic study in rats and in a 3-month intervention in humans highly exposed to aflatoxins. Uniform particle size NovaSil (UPSN) is a refined material derived from parent NS; it contains lower levels of dioxins/furans, and has been selected for a more consistent uniform particle size. Nevertheless, the efficacy and potential safety/toxicity of UPSN for long term-use has not yet been determined. In this research, 4-week-old male and female Sprague Dawley rats were fed rations free of clay (control) and containing UPSN at low dose (0.25%) and high dose (2%) for 13 weeks. AFB1 sorption characteristics remained the same for both clays. When compared to the control, total body weight gain was unaffected in either sex at the doses tested. No UPSN-dependent differences in relative organ weights or gross appearance were observed. Isolated differences between UPSN groups and the control were observed for some biochemical parameters and selected vitamins and minerals. None of these differences were dose-dependent, and all parameters fell between ranges reported as normal for rats less than 6 month old. The Na/K ratio, Na and vitamin E concentrations were the only parameters that were increased in both males and females in the low dose and high dose UPSN groups. Serum Zn levels in males from the 2% UPSN treatment were lower compared to the control. Serum K levels were lower in the males of UPSN groups than in the control. However, neither Na/K ratio, K, nor Zn values were dose dependent and fell outside ranges reported as normal. These results suggest that dietary inclusion of UPSN at levels as high as 2% (w/w) does not result in overt toxicity. Nevertheless, further research on the effects of clays on Na, Zn, K and vitamin E is

  17. Preparation of Anisotropic and Oriented Particles on a Flexible Substrate.

    PubMed

    Chekini, Mahshid; Cataldi, Ugo; Maroni, Plinio; Guénée, Laure; Černý, Radovan; Bürgi, Thomas

    2015-12-01

    Elongated plasmonic nanoparticles show superior optical properties when compared to spherical ones. Facile, versatile and cost-effective bottom-up approaches for fabrication of anisotropic nanoparticles in solution have been developed. However, fabrication of 2-D plasmonic templates from elongated nanoparticles with spatial arrangement at the surface is still a challenge. We used controlled seed-mediated growth in the presence of porous and functionalized surface of flexible polydimethylsiloxane (PDMS) templates to provide directional growth and formation of elongated gold nanoparticles (AuNPs). Atomic force microscopy (AFM) and spectroscopy revealed embedding of the particles within the functionalized porous surface of PDMS. Nanoparticles shapes were observed with transmission electron microscope (TEM), UV-Vis spectroscopy, and X-ray powder diffraction (XRPD) measurements, which revealed an overall orientation of particles at the surface. Anisotropic and oriented particles on a flexible substrate are of interest for sensing applications. PMID:26575589

  18. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions

    SciTech Connect

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, E.; Lohmann, U.; Baltensperger, Urs; Cziczo, Daniel J.

    2009-11-01

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of particular interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation with respect to liquid water similar to atmospheric conditions. In this study the sub-saturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols was determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were used. Aerosols were generated both with a wet and a dry disperser and the water uptake was parameterized via the hygroscopicity parameter, κ. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived κ values between 0.00 and 0.02. The latter value can be idealized as a particle consisting of 96.7% (by volume) insoluble material and ~3.3% ammonium sulfate. Pure clay aerosols were found to be generally less hygroscopic than real desert dust particles. All illite and montmorillonite samples had κ~0.003, kaolinites were least hygroscopic and had κ=0.001. SD (κ=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (κ=0.007) and ATD (κ=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles while immersed in an aqueous medium during atomization, thus indicating that specification of the generation method is critically important when presenting such data. Any atmospheric processing of

  19. Multisensor on-the-go mapping of readily dispersible clay, particle size and soil organic matter

    NASA Astrophysics Data System (ADS)

    Debaene, Guillaume; Niedźwiecki, Jacek; Papierowska, Ewa

    2016-04-01

    Particle size fractions affect strongly the physical and chemical properties of soil. Readily dispersible clay (RDC) is the part of the clay fraction in soils that is easily or potentially dispersible in water when small amounts of mechanical energy are applied to soil. The amount of RDC in the soil is of significant importance for agriculture and environment because clay dispersion is a cause of poor soil stability in water which in turn contributes to soil erodibility, mud flows, and cementation. To obtain a detailed map of soil texture, many samples are needed. Moreover, RDC determination is time consuming. The use of a mobile visible and near-infrared (VIS-NIR) platform is proposed here to map those soil properties and obtain the first detailed map of RDC at field level. Soil properties prediction was based on calibration model developed with 10 representative samples selected by a fuzzy logic algorithm. Calibration samples were analysed for soil texture (clay, silt and sand), RDC and soil organic carbon (SOC) using conventional wet chemistry analysis. Moreover, the Veris mobile sensor platform is also collecting electrical conductivity (EC) data (deep and shallow), and soil temperature. These auxiliary data were combined with VIS-NIR measurement (data fusion) to improve prediction results. EC maps were also produced to help understanding RDC data. The resulting maps were visually compared with an orthophotography of the field taken at the beginning of the plant growing season. Models were developed with partial least square regression (PLSR) and support vector machine regression (SVMR). There were no significant differences between calibration using PLSR or SVMR. Nevertheless, the best models were obtained with PLSR and standard normal variate (SNV) pretreatment and the fusion with deep EC data (e.g. for RDC and clay content: RMSECV = 0,35% and R2 = 0,71; RMSECV = 0,32% and R2 = 0,73 respectively). The best models were used to predict soil properties from the

  20. Hysteretic dynamics of active particles in a periodic orienting field

    PubMed Central

    Romensky, Maksym; Scholz, Dimitri; Lobaskin, Vladimir

    2015-01-01

    Active motion of living organisms and artificial self-propelling particles has been an area of intense research at the interface of biology, chemistry and physics. Significant progress in understanding these phenomena has been related to the observation that dynamic self-organization in active systems has much in common with ordering in equilibrium condensed matter such as spontaneous magnetization in ferromagnets. The velocities of active particles may behave similar to magnetic dipoles and develop global alignment, although interactions between the individuals might be completely different. In this work, we show that the dynamics of active particles in external fields can also be described in a way that resembles equilibrium condensed matter. It follows simple general laws, which are independent of the microscopic details of the system. The dynamics is revealed through hysteresis of the mean velocity of active particles subjected to a periodic orienting field. The hysteresis is measured in computer simulations and experiments on unicellular organisms. We find that the ability of the particles to follow the field scales with the ratio of the field variation period to the particles' orientational relaxation time, which, in turn, is related to the particle self-propulsion power and the energy dissipation rate. The collective behaviour of the particles due to aligning interactions manifests itself at low frequencies via increased persistence of the swarm motion when compared with motion of an individual. By contrast, at high field frequencies, the active group fails to develop the alignment and tends to behave like a set of independent individuals even in the presence of interactions. We also report on asymptotic laws for the hysteretic dynamics of active particles, which resemble those in magnetic systems. The generality of the assumptions in the underlying model suggests that the observed laws might apply to a variety of dynamic phenomena from the motion of

  1. Hysteretic dynamics of active particles in a periodic orienting field.

    PubMed

    Romensky, Maksym; Scholz, Dimitri; Lobaskin, Vladimir

    2015-07-01

    Active motion of living organisms and artificial self-propelling particles has been an area of intense research at the interface of biology, chemistry and physics. Significant progress in understanding these phenomena has been related to the observation that dynamic self-organization in active systems has much in common with ordering in equilibrium condensed matter such as spontaneous magnetization in ferromagnets. The velocities of active particles may behave similar to magnetic dipoles and develop global alignment, although interactions between the individuals might be completely different. In this work, we show that the dynamics of active particles in external fields can also be described in a way that resembles equilibrium condensed matter. It follows simple general laws, which are independent of the microscopic details of the system. The dynamics is revealed through hysteresis of the mean velocity of active particles subjected to a periodic orienting field. The hysteresis is measured in computer simulations and experiments on unicellular organisms. We find that the ability of the particles to follow the field scales with the ratio of the field variation period to the particles' orientational relaxation time, which, in turn, is related to the particle self-propulsion power and the energy dissipation rate. The collective behaviour of the particles due to aligning interactions manifests itself at low frequencies via increased persistence of the swarm motion when compared with motion of an individual. By contrast, at high field frequencies, the active group fails to develop the alignment and tends to behave like a set of independent individuals even in the presence of interactions. We also report on asymptotic laws for the hysteretic dynamics of active particles, which resemble those in magnetic systems. The generality of the assumptions in the underlying model suggests that the observed laws might apply to a variety of dynamic phenomena from the motion of

  2. Radiological characteristics of charged particle interactions in the first clay-nanoparticle dichromate gel dosimeter

    NASA Astrophysics Data System (ADS)

    Taylor, M. L.; Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Fukasaku, K.; Furuta, T.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2013-06-01

    The incorporation of clay nanoparticles into gel dosimeters shows promise for significant diffusion reduction - but to what extent does the presence of the nano-clay influence charged particle interactions and, in particular, what is the impact on water equivalence? In this work, we quantify the radiological characteristics of electron, proton and carbon ion interactions in the RIKEN dichromate nanoclay gel and specifically evaluate the water equivalence over a broad energy range. Results indicate that the radiological properties are sufficiently representative of tissues that this low-diffusion gel could readily be used for validation of complex dose distributions. Electron and proton ranges are within 1 % of those in water. Mean effective atomic numbers for electron interactions in the range 10 keV - 10 GeV are within 1 % of those of water which, coupled with the similar mass density, ultimately means the overall impact on dose distributions is not great. The range of C6+ ions in the nanoclay gel is closer to that of water (< 4 %) than a common polymer gel dosimeter (< 7 %), though experimentally measured R1 values indicate an over-response at low doses.

  3. Oriented clay nanopaper from biobased components--mechanisms for superior fire protection properties.

    PubMed

    Carosio, F; Kochumalayil, J; Cuttica, F; Camino, G; Berglund, L

    2015-03-18

    The toxicity of the most efficient fire retardant additives is a major problem for polymeric materials. Cellulose nanofiber (CNF)/clay nanocomposites, with unique brick-and-mortar structure and prepared by simple filtration, are characterized from the morphological point of view by scanning electron microscopy and X-ray diffraction. These nanocomposites have superior fire protection properties to other clay nanocomposites and fiber composites. The corresponding mechanisms are evaluated in terms of flammability (reaction to a flame) and cone calorimetry (exposure to heat flux). These two tests provide a wide spectrum characterization of fire protection properties in CNF/montmorrilonite (MTM) materials. The morphology of the collected residues after flammability testing is investigated. In addition, thermal and thermo-oxidative stability are evaluated by thermogravimetric analyses performed in inert (nitrogen) and oxidative (air) atmospheres. Physical and chemical mechanisms are identified and related to the unique nanostructure and its low thermal conductivity, high gas barrier properties and CNF/MTM interactions for char formation. PMID:25723913

  4. MD Simulation of Particle Orientation in Magnetic Inks

    NASA Astrophysics Data System (ADS)

    Visscher; Günal

    1997-03-01

    We have done molecular-dynamics type simulations of particle re-orientation in a magnetic colloid, by a magnetic field during tape and disk manufacture. The model takes into account switching (in a Stoner- Wohlfarth model) as well as particle translation and rotation in response to magnetic, steric, Brownian, and hydrodynamic drag forces and torques. Magnetic interactions are fully included; hysteresis loops with and without magnetic interaction will be displayed, with corresponding Δ M curves. Images of the network structure at various points of the hysteresis loop will be shown. Further information is available at http:// www.mint.ua.edu/colloids/march.html.

  5. Measuring the isoelectric point of the edges of clay mineral particles: the case of montmorillonite.

    PubMed

    Pecini, Eliana M; Avena, Marcelo J

    2013-12-01

    The isoelectric point (IEP) of the edge surface of a montmorillonite sample was determined by using electrophoretic mobility measurements. This parameter, which is fundamental for the understanding of the charging behavior of clay mineral surfaces, was never measured so far because of the presence of permanent negative charges within the montmorillonite structure, charges that mask the electrokinetic behavior of the edges. The strategy was to block or neutralize the structural charges with two different cations, methylene blue (MB(+)) and tetraethylenepentaminecopper(II) ([Cu(tetren)](2+)), so that the charging behavior of the particles becomes that of the edge surfaces. Adsorption isotherms of MB(+) and [Cu(tetren)](2+) at different ionic strengths (NaCl) were performed to establish the uptakes that neutralize the cation exchange capacity (CEC, 0.96 meq g(-1)) of the sample. At high adsorptive concentrations, there was a superequivalent adsorption of MB(+) (adsorption exceeding the CEC) and an equivalent adsorption of [Cu(tetren)](2+) (adsorption reaching the CEC). In both cases, structural charges were neutralized at uptakes very close to the CEC. Zeta potential (ζ) vs pH data at different ionic strengths of montmorillonite with adsorbed MB(+) allowed to estimate an upper limit of the edge's IEP, 5.3 ± 0.2. The same kind of data obtained with adsorbed [Cu(tetren)](2+) provided a lower limit of the IEP, 4.0 ± 0.2. These values are in agreement with previously informed IEP and point of zero charge of pyrophyllite, which is structurally analogous to montmorillonite but carries no permanent charges. The importance of knowing the IEP of the edge surface of clay minerals is discussed. This value characterizes the intrinsic reactivity of edges, that is, the protonating capacity of edge groups in absence of any electric field generated by structural charges. It also allows us to correct relative edge charge vs pH curves obtained by potentiometric titrations and to

  6. Object Oriented Design and the Standard Model of particle physics

    NASA Astrophysics Data System (ADS)

    Lipovaca, Samir

    2007-04-01

    Inspired by the computer as both tool and metaphor, a new path emerges toward understanding life, physics, and existence. The path leads throughout all of nature, from the interior of cells to inside black holes. This view of science is based on the idea that information is the ultimate ``substance'' from which all things are made. Exploring this view, we will focus on Object - Oriented (OO) design as one of the most important designs in software development. The OO design views the world as composed of objects with well defined properties. The dynamics is pictured as interactions among objects. Interactions are mediated by messages that objects exchange with each other. This description closely resembles the view of the elementary particles world created by the Standard Model of particle physics. The object model (OM) provides a theoretical foundation upon which the OO design is built. The OM is based on the principles of abstraction, encapsulation, modularity and hierarchy. We will show that the Standard Model of particle physics follows the OM principles.

  7. The effect of clay particles on the activity of suspended autotrophic nitrifying bacteria and on the performance of an air-lift reactor.

    PubMed

    Vieira, M J; Pacheco, A P; Pinho, I A; Melo, L F

    2001-02-01

    Clay minerals have some properties, namely a high surface area and the ability of ion exchange that may exert some effects on microbial systems. It is often difficult to know the way the clay is exerting its influence and whether its presence improves a given metabolic process. The present work concerns the study of the effect of the addition of powdered kaolin to autotrophic nitrification systems, and includes the study of the effects of the particles on the activity of a suspended nitrifying bacteria consortium and on the performance of an air-lift biofilm reactor used for tertiary nitrification. Concerning the suspended culture, kaolin particles produced stimulation on the specific endogenous and exogenous respiration rates of the bacteria, probably due to a nutritional effect supplied by the clay. This effect was more pronounced for the ammonia oxidation rates, although nitrite oxidation was also enhanced but to a lesser extent. In respect to the presence of kaolin particles in the air-lift reactor, the results obtained indicate that the clay particles become incorporated in the biofilm pellets, but do not change significantly their thickness or their shape. However, nitrate production decreased when the concentration of particles increased. The low adsorption of ammonia by the kaolin indicated that the clay particles embedded in the biofilm did not probably retain the ions. Although it was not proved, precipitation of salts may have occurred. PMID:11349371

  8. Clay Minerals

    SciTech Connect

    Mueller, Karl T.; Sanders, Rebecca L.; Washton, Nancy M.

    2014-03-14

    Clay minerals are important components of the environment and are involved or implicated in processes such as the uptake of pollutants and the release of nutrients and as potential platforms for a number of chemical reactions. Owing to their small particle sizes (typically, on the order of microns or smaller) and mixing with a variety of other minerals and soil components, advanced characterization methods are needed to study their structures, dynamics, and reactivities. In this article, we describe the use of solid-state NMR methods to characterize the structures and chemistries of clay minerals. Early one-pulse magic-angle spinning (MAS) NMR studies of 27Al and 29Si have now been enhanced and extended with new studies utilizing advanced methodologies (such as Multiple Quantum MAS) as well as studies of less-sensitive nuclei. In additional work, the issue of reactivity of clay minerals has been addressed, including studies of reactive surface area in the environment. Utilizations of NMR-sensitive nuclides within the clay minerals themselves, and in molecules that react with specific sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.

  9. Investigating particle orientation in cirrus clouds by measuring backscattering phase matrices with lidar.

    PubMed

    Kaul, Bruno V; Samokhvalov, Ignatii V; Volkov, Sergei N

    2004-12-20

    The relation between the orientation of particles in ice-crystal clouds and backscattering phase matrices (BSPMs) is considered. Parameters characterizing the predominant orientation of particles in the azimuthal direction and in the horizontal position are presented. The parameters are expressed through BSPM elements. A technique for measuring BSPM elements with lidar is described. Examples of some measurements are presented along with a statistical generalization of the results from more than 400 BSPM measurements. It is found that the orientation of coarse particles with large diameters in an azimuthal direction and in a horizontal position is more probable than in a random direction. However, the orientation of large particles is often masked by small particles that are not subject to the effect of orienting factors. Thus the mean parameters characterizing the state of orientation of particles in clouds as a whole correspond to weak orientation. It is supposed that the orientation of particles in the azimuthal direction is caused by wind-velocity pulsations. PMID:15646781

  10. Measuring the orientation and rotation rate of 3D printed particles in turbulent flow

    NASA Astrophysics Data System (ADS)

    Voth, Greg; Marcus, Guy G.; Parsa, Shima; Kramel, Stefan; Ni, Rui; Cole, Brendan

    2014-11-01

    The orientation distribution and rotations of anisotropic particles plays a key role in many applications ranging from icy clouds to papermaking and drag reduction in pipe flow. Experimental access to time resolved orientations of anisotropic particles has not been easy to achieve. We have found that 3D printing technology can be used to fabricate a wide range of particle shapes with smallest dimension down to 300 μm. So far we have studied rods, crosses, jacks, tetrads, and helical shapes. We extract the particle orientations from stereoscopic video images using a method of least squares optimization in Euler angle space. We find that in turbulence the orientation and rotation rate of many particles can be understood using a simple picture of alignment of both the vorticity and a long axis of the particle with the Lagrangian stretching direction of the flow. This research is supported by NSF Grant DMR-1208990.

  11. Measuring the orientation and rotation rate of 3D printed particles in turbulent flow

    NASA Astrophysics Data System (ADS)

    Voth, Greg; Kramel, Stefan; Cole, Brendan

    2015-03-01

    The orientation distribution and rotations of anisotropic particles plays a key role in many applications ranging from icy clouds to papermaking and drag reduction in pipe flow. Experimental access to time resolved orientations of anisotropic particles has not been easy to achieve. We have found that 3D printing technology can be used to fabricate a wide range of particle shapes with smallest dimension down to 300 ?m. So far we have studied rods, crosses, jacks, tetrads, and helical shapes. We extract the particle orientations from stereoscopic video images using a method of least squares optimization in Euler angle space. We find that in turbulence the orientation and rotation rate of many particles can be understood using a simple picture of alignment of both the vorticity and a long axis of the particle with the Lagrangian stretching direction of the flow.

  12. Stereological estimation of particle shape and orientation from volume tensors.

    PubMed

    Rafati, A H; Ziegel, J F; Nyengaard, J R; Jensen, E B Vedel

    2016-09-01

    In the present paper, we describe new robust methods of estimating cell shape and orientation in 3D from sections. The descriptors of 3D cell shape and orientation are based on volume tensors which are used to construct an ellipsoid, the Miles ellipsoid, approximating the average cell shape and orientation in 3D. The estimators of volume tensors are based on observations in several optical planes through sampled cells. This type of geometric sampling design is known as the optical rotator. The statistical behaviour of the estimator of the Miles ellipsoid is studied under a flexible model for 3D cell shape and orientation. In a simulation study, the lengths of the axes of the Miles ellipsoid can be estimated with coefficients of variation of about 2% if 100 cells are sampled. Finally, we illustrate the use of the developed methods in an example, involving neurons in the medial prefrontal cortex of rat. PMID:26823192

  13. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles

    PubMed Central

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B.; Chen, Wenli

    2015-01-01

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of −3.0 ± 0.4 nN and −330 ± 43 aJ (10−18 J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions. PMID:26585552

  14. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles.

    PubMed

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B; Chen, Wenli

    2015-01-01

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of -3.0 ± 0.4 nN and -330 ± 43 aJ (10(-18) J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions. PMID:26585552

  15. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles

    NASA Astrophysics Data System (ADS)

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B.; Chen, Wenli

    2015-11-01

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of -3.0 ± 0.4 nN and -330 ± 43 aJ (10-18 J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions.

  16. Geoscientific Applications of Particle Detection and Imaging Techniques withSpecial Focus on the Monitoring Clay Mineral Reactions

    NASA Astrophysics Data System (ADS)

    Warr, Laurence N.; Grathoff, Georg H.

    The combined use of focused X-ray, electron, and ion beams offers a diverse range of analytical capabilities for characterizing nanoscale mineral reactions that occur in hydrous environments. Improved image and microanalytical techniques (e.g., electron diffraction and energy-dispersive X-ray spectroscopy), in combination with controlled sample environments, are currently leading to new advances in the understanding of fluid-mineral reactions in the Earth Sciences. One group of minerals playing a key role in the containment of radioactive waste and the underground storage of CO2 is the clay minerals: these small, expandable, and highly adsorbent hydrous phyllosilicates form important low-permeable geological barriers by which waste can be safely deposited. In this article we summarize some of the state-of-the-art particle and imaging techniques employed to predict the behavior of both engineered and natural clay mineral seals in proposed storage sites. Particular attention is given to two types of low-permeability geomaterials: engineered bentonite backfill and natural shale in the subsurface. These materials have contrasting swelling properties and degrees of chemical stability that require detailed analytical study for developing suitable disposal or storage solutions.

  17. The Use of Small-Particle Sized TiO2 Supported on Clays as Photocatalytic Materials: A Low- Cost Alternative Technology for the Degradation of Air Pollutants

    NASA Astrophysics Data System (ADS)

    Kibanova, D.; Trejo, M.; Destaillats, H.; Cervini-Silva, J.

    2007-05-01

    Assisted photocatalysis by TiO2 is an advanced oxidation process that has been employed for air and water remediation. Clays are natural porous materials bearing high surface areas and interlayer spacing that allows entrapment of small-sized particles. Pillared clays exchanged with small-sized TiO2 can constitute materials with interesting photocatalytic properties because high surface area values and large contents of mesospores, which enables analyte trapping. Furthermore, intercalation at the clay interlayer enables TiO2 to become more resistant to aggregation when in solution. Just recently it has been reported that clays can lead to increases in the photocatalytic activity of TiO2 when the mesopores size is adequate to host organic solutes and ensure their effective interaction with the TiO2 particles. In this paper we study the photocatalytic properties of small-sized TiO2 supported on the following clay samples: Montmorillonite [SWy-2, Na0.2Ca0.1Al2Si4O10(OH)2(H2O)10 ] from Crook Country, Wyoming, USA; Hectorite [SHCa-1, Na0.4Mg2.7Li0.3Si4O10(OH)2 ] from San Bernardino. Country, California, USA; Kaolinite [KGa-1b, Al2Si2O5(OH)4 ] from Washington Country, Georgia, USA. Deposition of TiO2 on the clay surface was conducted by using a sol-gel synthetic method. Anatase TiO2 particles transformation at the clay interlayer was achieved by thermic treatment at 180 °C. Material characterization was conducted using FTIR microspectroscopy, Scanning Electron Microscopy (SEM), and XRD analysis. The organic compound used as probe was ethanol

  18. Orientation of particles in an electrorheological fluid under an electric field

    NASA Astrophysics Data System (ADS)

    Lan, Yucheng; Xu, Xiaoyu; Men, Shouqiang; Lu, Kunquan

    1999-10-01

    The orientation of the particles in an electrorheological fluid under an electric field has been studied. Triglycine sulfate (TGS)-wax mixtures were applied in this study. Here the TGS particles are in the ferroelectric phase with spontaneous polarization ps in the <010> direction at below the Curie temperature TC and become paraelectric without a permanent electric moment at above TC. By measuring x-ray-diffraction intensities of TGS/wax samples under an electric field at below and above TC, respectively, it is found that the particles with spontaneous polarization turn their ps vectors to the direction of the external electric field in addition to forming chains or columns. However, the particles without permanent moment only form chains or columns, in which no preferred orientation of the particles can be observed. The preferred orientation degree is determined by comparing the diffraction intensity in these two cases.

  19. Modified clay sorbents

    DOEpatents

    Fogler, H. Scott; Srinivasan, Keeran R.

    1990-01-01

    A novel modified clay sorbent and method of treating industrial effluents to remove trace pollutants, such as dioxins, biphenyls, and polyaromatics such as benzo(a)pyrene and pentachlorophenol. The novel clay sorbent has a composite structure in which the interlayer space of an expandable clay, such as smectite, is filled with polyvalent or multivalent inorganic cations which forces weaker surfactant cations to locate on the surface of the clay in such an orientation that the resulting composite is hydrophilic in nature. A specific example is cetylpyridinium-hydroxy aluminum-montmorillonite. In certain embodiments, a non-expanding clay, such as kaolinite, is used and surfactant cations are necessarily located on an external surface of the clay. A specific example is cetylpyridinium-kaolinite.

  20. EFFECT OF AQUEOUS PHASE PROPERTIES ON CLAY PARTICLE ZETA POTENTIAL AND ELECTRO-OSMOTIC PERMEABILITY: IMPLICATIONS FOR ELECTRO-KINETIC SOIL REMEDIATION PROCESSES

    EPA Science Inventory

    The influence of aqueous phase properties (pH, ionic strength and divalent metal ion concentration) on clay particle zeta potential and packed-bed electro-osmotic permeability was quantified. Although pH strongly altered the zeta potential of a Georgia kaolinite, it did not signi...

  1. Ball clay

    USGS Publications Warehouse

    Virta, Robert L.

    2010-01-01

    The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

  2. Intensity and polarization of light scattered by size distributions of randomly oriented nonspherical particles

    NASA Technical Reports Server (NTRS)

    Mishchenko, M. I.; Travis, L. D.

    1993-01-01

    Calculations of light scattering by small particles are important in many diverse fields of science and engineering. In many cases of practical interest, scattering particles are nonspherical and are distributed over sizes and orientations. However, accurate light scattering computations for ensembles of nonspherical particles are difficult and time-consuming, and the literature in which such calculations are reported is rather scarce. In this paper, the T-matrix approach, as extended recently to randomly oriented particles, is used to calculate rigorously light scattering by size distributions of randomly oriented axially symmetric particles. To model the variation of particle sizes in real ensembles, we use a power law distribution typical of some terrestrial aerosols. Contour plots of intensity and degree of linear polarization for polydisperse prolate and oblate spheroids of different aspect ratios and effective equivalent-sphere size parameters from 0 to 10 are calculated and compared with calculations for equivalent spheres. The angular scattering behavior of nonspherical polydispersions is found to be greatly different from that of spheres, while the scattering properties of oblate and prolate spheroids of the same aspect ratio are similar. With increasing particle size, both intensity and polarization become more shape-dependent. In general, nonspherical particles are stronger side scatterers and weaker backscatterers than equivalent spheres. With increasing aspect ratio of nonspherical particles polarization tends to be predominantly positive. Possible effects of particle nonsphericity on optical remote sensing of atmospheric aerosols are discussed.

  3. Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence.

    PubMed

    Cole, Brendan C; Marcus, Guy G; Parsa, Shima; Kramel, Stefan; Ni, Rui; Voth, Greg A

    2016-01-01

    Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with Rλ = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates. PMID:27404898

  4. Orientational glass in mixtures of elliptic and circular particles: structural heterogeneities, rotational dynamics, and rheology.

    PubMed

    Takae, Kyohei; Onuki, Akira

    2014-02-01

    Using molecular dynamics simulation with an angle-dependent Lennard-Jones potential, we study orientational glass with quadrupolar symmetry in mixtures of elliptic particles and circular impurities in two dimensions. With a mild aspect ratio (= 1.23) and a mild size ratio (= 1.2), we realize a plastic crystal at relatively high temperature T. With further lowering T, we find a structural phase transition for very small impurity concentration c and pinned disordered orientations for not small c. The ellipses are anchored by the impurities in the planar alignment. With increasing c, the orientation domains composed of isosceles triangles gradually become smaller, resulting in orientational glass with crystal order. In our simulation, the impurity distribution becomes heterogeneous during quenching from liquid, which then produces rotational dynamic heterogeneities. We also examine rheology in orientational glass to predict a shape memory effect and a superelasticity effect, where a large fraction of the strain is due to collective orientation changes. PMID:25353473

  5. Clays, specialty

    USGS Publications Warehouse

    Virta, R.L.

    1998-01-01

    Part of a special section on the state of industrial minerals in 1997. The state of the specialty clay industry worldwide for 1997 is discussed. The specialty clays mined in the U.S. are ball clay, fuller's earth, bentonite, fire clay, and kaolin. Sales of specialty clays in the U.S. were around 17 Mt in 1997. Approximately 53 kt of specialty clays were imported.

  6. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    In 2005, four companies including H.C. Spinks Clay, Kentucky-Tennessee Clay, Old Hickory Clay and Unimin mined ball clay in four states. Based on a preliminary survey of the ball clay industry, production reached 1.32 Mt valued at $53.3 million. Tennessee was the leading ball clay producer state with 61% of domestic production, followed by Texas, Mississippi and Kentucky.

  7. Composition and orientation relationships of constituent particles in 3xxx aluminum alloys

    NASA Astrophysics Data System (ADS)

    Muggerud, Astrid Marie F.; Li, Yanjun; Holmestad, Randi

    2014-02-01

    Constituent and dispersoid phases in two Direct Chill-cast 3xxx aluminum alloys after low-temperature annealing, with different silicon content have been studied. The lattice parameters, chemical composition, morphology and orientations relationships of constituent particles with regard to Al matrix have been addressed. Al?(Fe,Mn) is found to be the most prominent constituent phase in the alloy with a low Si content. The orientation relationship between aluminum matrix and this phase is determined as ?, ?, which is consistent with the orientation relationships of Al?(Fe,Mn) dispersoids. ?-Al(Fe,Mn)Si constituent particles in the Si rich alloy have been found to have various possible orientations. A gradient of Fe content is found in the ?-Al(Fe,Mn)Si dispersoids due to slow diffusion of Fe into dispersoids during annealing.

  8. Single particle and collective orientational relaxation in an anisotropic liquid near the isotropic-nematic transition

    NASA Astrophysics Data System (ADS)

    Perera, A.; Ravichandran, S.; Moreau, M.; Bagchi, B.

    1997-01-01

    We report molecular dynamics simulation results for the single particle and collective orientational correlations for Gay-Berne fluid of anisotropy parameters κ=3 and κ=5. The following significant results are reported. (i) The decay of collective orientational relaxation of rank two is found to slow down appreciably while approaching the isotropic-nematic (I-N) transition. It eventually becomes even slower than the single particle orientational relaxation of rank one. Surprisingly, even the latter shows a marked slowing down near the I-N transition. (ii) Analysis of the long-time behavior shows a breakdown of the rank dependence predicted by the Debye law in the same region. (iii) An analysis of the memory functions of the orientational time-correlation functions shows that for the collective relaxation surprisingly approaches a Markovian behavior near the I-N transition.

  9. Modeling the Elastic Modulus of Polymer/clay Nanocomposites with the Effective Particle Approach

    NASA Astrophysics Data System (ADS)

    Anthoulis, George I.; Kontou, Evagelia; Kalkanis, Konstantinos

    2008-08-01

    The enhancement in mechanical properties of nanocomposites in terms of Young's modulus has been modeled with a number of micromechanical models. Application of the `effective particle' approach to models previously developed for the calculation of the stiffness of nanocomposites such as the Chen-Cheng and Odegard models, improves the agreement between theory and experiment only to a modest extent, because in these models only one kind of inhomogeneity is considered. On the contrary, Taya and Chou model initially proposed for conventional composites with two separate kinds of inclusions was proven to effectively describe the nanocomposite behaviour. The two types of inhomogeneities were considered to be the exfoliated layers and the intercalated particles, respectively. Four nanocomposite systems were examined, prepared and characterized elsewhere, and parameters required for the analysis such as the number of silicate layers in a stack, the length of the platelets and interlayer spacing were estimated from quantitative digital image analysis performed on transmission electron microscopy photomicrographs and wide angle X-ray scattering studies. The present approach reveals a method for quantification of both the degree of exfoliation as well as degree of reinforcement through micromechanical modeling, which is often formidable with available characterization techniques.

  10. Clay Play

    ERIC Educational Resources Information Center

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  11. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

  12. Clay-oil droplet suspensions in electric fields

    NASA Astrophysics Data System (ADS)

    Rozynek, Zbigniew; Fossum, Jon Otto; Kjerstad, Knut; Mikkelsen, Alexander; Castberg, Rene

    2012-02-01

    Silicone oil droplets containing synthetic smectite clay submerged in immiscible organic oil have been studied by observing clay particle movement and oil circulation when an electric field is applied. Results show how electric field strength, dielectric and electrorheological properties as well as electrohydrodynamics determine the fluid flow and clay particle formation. In a presence of the DC electric fields the clay particles formed a ribbon-like structure onto the inner surface of the droplet. The structure consists of short chain-like clay elements orienting parallel to the electric field direction. It is suggested that a combination of two phenomena, namely the induced viscous flow (electrohydrodynamic effect) and the polarization of the clay particles (dielectric effect), contribute to the ribbon-like structure formation. -/abstract- References [1] G. Taylor, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences 291 (1966) 159--166. [2] J. R. Melcher and G. I. Taylor, Annual Review of Fluid Mechanics 1 (1969) 111--146. [3] H. Sato, N. Kaji, T. Mochizuki, and Y. H. Mori, Physics of Fluids 18 (2006) 127101. [4] D. A. Saville, Annual Review of Fluid Mechanics 29 (1997) 27--64. [5] J. O. Fossum, Y. M'eheust, K. P. S. Parmar, K. D. Knudsen, K. J. Måløy, and D. M. Fonseca Europhysics Letters 74

  13. Prediction of particle orientation in simple upsetting process of NdFeB magnets

    SciTech Connect

    Chang, Chao-Cheng; Hsiao, Po-Jen; You, Jr-Shiang; Chen, Yen-Ju; Chang, Can-Xun

    2013-12-16

    The magnetic properties of NdFeB magnets are strongly affected by crystallographic texture which is highly associated with particle orientation. This study proposed a method for predicting the particle orientation in the simple upsetting process of NdFeB magnets. The method is based on finite element simulation with flow net analysis. The magnets in a cylindrical form were compressed by two flat dies in a chamber filled with argon at 750°C. Three forming speeds were taken into account in order to obtain flow stress curves used in simulations. The micrographs of the cross sections of the deformed magnets show that the particle deformation significantly increases with the compression. The phenomenon was also predicted by the proposed method. Both simulated and experimental results show that the inhomogeneity of the texture of the NdFeB magnets can be increased by the simple upsetting process. The predicted particle orientations were in a good agreement with those examined in the deformed magnets. The proposed method for predicting particle orientations can also be used in other forming processes of NdFeB magnets.

  14. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2007-01-01

    The article offers information on ball clay. Among the companies that mine ball clay in the U.S. are H.C. Spinks Clay, Kentucky-Tennessee Clay and Old Hickory Clay. In 2006, an estimated 1.2 million tons of the mineral was sold or used domestically and exported. Forty-percent of the total sales is accounted for ceramic floor and wall tile followed by sanitaryware and miscellaneous ceramics. Its average value was $ 45 per ton in 2006.

  15. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global ball clay mining industry, particularly in the U.S., as of June 2011. It cites several firms that are involved in ball clay mining in the U.S., including HC Spins Clay Co. Inc., the Imerys Group and Old Hickory Clay Co. Among the products made from ball clay are ceramic tiles, sanitaryware, as well as fillers, extenders and binders.

  16. Orientational order and translational dynamics of magnetic particle assemblies in liquid crystals.

    PubMed

    Peroukidis, Stavros D; Klapp, Sabine H L

    2016-08-10

    Implementing extensive molecular dynamics simulations we explore the organization of magnetic particle assemblies (clusters) in a uniaxial liquid crystalline matrix comprised of rodlike particles. The magnetic particles are modelled as soft dipolar spheres with diameter significantly smaller than the width of the rods. Depending on the dipolar strength coupling the magnetic particles arrange into head-to-tail configurations forming various types of clusters including rings (closed loops) and chains. In turn, the liquid crystalline matrix induces long range orientational ordering to these structures and promotes their diffusion along the director of the phase. Different translational dynamics are exhibited as the liquid crystalline matrix transforms either from isotropic to nematic or from nematic to smectic state. This is caused due to different collective motion of the magnetic particles into various clusters in the anisotropic environments. Our results offer a physical insight for understanding both the structure and dynamics of magnetic particle assemblies in liquid crystalline matrices. PMID:27460190

  17. Modeling emissivity of low-emissivity coating containing horizontally oriented metallic flake particles

    NASA Astrophysics Data System (ADS)

    Chen, Shuai; Yuan, Le; Weng, Xiaolong; Deng, Longjiang

    2014-11-01

    The scattering and absorption cross sections of horizontally oriented metallic flake particles are estimated by extended geometric optics that includes diffraction and edge effects. Emissivity of the coating containing those particles is calculated using Kubelka-Munk theory. The dependence of emissivity of the coating on the radius, thickness, content of metallic flake particles and coating thickness is discussed. Finally, theoretical results are compared with the experimental measurements with Al/acrylic resin coating system and the results show that simulation values are in good agreement with experimental ones.

  18. Application of randomly oriented spheroids for retrieval of dust particle parameters from multiwavelength lidar measurements

    NASA Astrophysics Data System (ADS)

    Veselovskii, I.; Dubovik, O.; Kolgotin, A.; Lapyonok, T.; di Girolamo, P.; Summa, D.; Whiteman, D. N.; Mishchenko, M.; Tanré, D.

    2010-11-01

    Multiwavelength (MW) Raman lidars have demonstrated their potential to profile particle parameters; however, until now, the physical models used in retrieval algorithms for processing MW lidar data have been predominantly based on the Mie theory. This approach is applicable to the modeling of light scattering by spherically symmetric particles only and does not adequately reproduce the scattering by generally nonspherical desert dust particles. Here we present an algorithm based on a model of randomly oriented spheroids for the inversion of multiwavelength lidar data. The aerosols are modeled as a mixture of two aerosol components: one composed only of spherical and the second composed of nonspherical particles. The nonspherical component is an ensemble of randomly oriented spheroids with size-independent shape distribution. This approach has been integrated into an algorithm retrieving aerosol properties from the observations with a Raman lidar based on a tripled Nd:YAG laser. Such a lidar provides three backscattering coefficients, two extinction coefficients, and the particle depolarization ratio at a single or multiple wavelengths. Simulations were performed for a bimodal particle size distribution typical of desert dust particles. The uncertainty of the retrieved particle surface, volume concentration, and effective radius for 10% measurement errors is estimated to be below 30%. We show that if the effect of particle nonsphericity is not accounted for, the errors in the retrieved aerosol parameters increase notably. The algorithm was tested with experimental data from a Saharan dust outbreak episode, measured with the BASIL multiwavelength Raman lidar in August 2007. The vertical profiles of particle parameters as well as the particle size distributions at different heights were retrieved. It was shown that the algorithm developed provided substantially reasonable results consistent with the available independent information about the observed aerosol event.

  19. A comparison of the closed-face cassette at different orientations while measuring total particles.

    PubMed

    Cook, David M; Sleeth, Darrah K; Thiese, Matthew S; Larson, Rodney R

    2015-01-01

    The current method for sampling aerosols using the 37-mm closed-face cassette (CFC) sampler is based on the orientation of the cassette at ∼45° from horizontal. There is some concern as to whether this method is appropriate and may be underestimating exposures. An alternative orientation at ∼0° (horizontal) has been discussed. This research compared the CFC's orientation at 45° from horizontal to the proposed orientation at horizontal, 0° in a controlled laboratory setting. The particles used in this study were fused alumina oxide in four sizes, approximately 9.5 μm, 12.8 μm, 18 μm, and 44.3 μm in aerodynamic diameter. For each test, one aerosol was dispersed in a wind tunnel operating at 0.2 m/s with samplers mounted in the breathing zone of a rotating mannequin. A sampling event consisted of four pairs of samplers, placed side by side (one pair at 45° and another at 0° cassette orientation), and exposed for a period of 45 minutes. A total of 12 sampling events, 3 sample events per particle size, were conducted with a total of 94 samples collected. Mass concentration measurements were compared to assess the relationship between the sampler orientations of the cassettes. In addition, the relationship between the mass collected on the cassette filter and on the interior walls of the cassette was also assessed. The results indicated that there was no significant difference between the measured concentrations based on the orientation of the CFCs. The amount of mass collected on the interior walls of the cassettes was relatively low (<5%) compared to expected (up to 100%) wall losses for both orientations. PMID:25337937

  20. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, November 9, 1991--February 8, 1992

    SciTech Connect

    Olson, E.S.

    1995-10-01

    The investigation of methods for the production and testing of iron-pillared clay catalysts was continued in this quarter. The surface area of the mixed alumina/iron pillared clay catalyst decreased to 51 m{sup 2}/g on sulfidation. Thus the stability of the alumina pillars during the sulfidation and thermal treatments prevented the total collapse that occurred in the case of the iron-pillared clays. Previously the mixed alumina/iron pillared clays were tested for hydrocracking activities with bibenzyl. This testing was extended to a determination of activity with a second model compound substrate (pyrene), representative of the polynuclear aromatic systems present in coal. Testing of the mixed alumina/iron-pillared catalysts with 1-methylnaphthalene gave interesting results that demonstrate shape selectivity. The clay-supported iron hydroxyoxide catalysts prepared by impregnation of iron species on acidic clays were further investigated. Sulfidation of these catalysts using the carbon disulfide in situ method gave hydrocracking activities with bibenzyl that were somewhat less than those obtained by presulfidation with H{sub 2}/H{sub 2}S mixtures. Liquefaction of Wyodak subbituminous coal was very successful with the iron impregnated clay catalyst, giving a highly soluble product. High conversions were also obtained with the mixed alumina/iron-pillared clay catalyst, but the yield of oil-solubles was considerably lower. Several new catalysts were synthesized with the idea of decreasing the pillar density and thereby increasing the micropore volume. These catalysts were prepared by first pillaring with an organic ammonium pillaring agent, then introducing a lower number of silica or alumina pillars. Finally the iron component was added either before or after thermal removal of organic pillars.

  1. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, February 9, 1992--May 8, 1992

    SciTech Connect

    Olson, E.S.

    1995-10-01

    An investigation of new methods for the production of iron-pillared clay catalysts and clay-supported iron hydroxyoxide catalysts and the determination of their catalytic activities was continued in this quarter. Previous work in this project showed that a catalyst prepared by adding ferric nitrate and ammonia to an acid-washed clay gave an active catalyst following sulfidation. Further testing of this catalyst with a model compound showed that its hydrocracking activity was considerably lower when used in 10% concentration rather than 50%. In contrast, the mixed iron/alumina pillared clay catalysts were still highly effective at 10% concentration and gave good conversions at one and two hour reaction times. An investigation of preparation methods demonstrated that calcination of both the iron hydroxyoxide-impregnated clay and the mixed iron/alumina pillared clays is essential for activity. High activity was obtained for these catalysts only when they were removed from the aqueous media rapidly, dried, and calcined. The use of ferric sulfate to prepare a clay-supported sulfated iron catalyst was attempted, the resulting catalyst was relatively inactive for hydrocracking. Several new catalysts were synthesized with the idea of decreasing the pillar density and thereby increasing the micropore volume. A zirconia-pillared clay with low pillar density was prepared and intercalated with triiron complex. The hydrocracking activity of this catalyst was somewhat lower than that of the mixed alumina/iron-pillared catalyst. Other new catalysts, that were prepared by first pillaring with an organic ammonium pillaring agent, then introducing a lower number of silica or alumina pillars, and finally the iron component, were also tested. The mixed alumina/iron-pillared catalysts was further tested at low concentration for pyrene hydrogenating and hydrocracking activities.

  2. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Four companies — H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co. and Unimin Corp. — mined ball clay in five U.S. states in 2012. Production, on the basis of preliminary data, was 900 kt (992,000 st), with an estimated value of $42.3 million. This was a slight increase in tonnage from 886 kt (977,000 st), with a value of $40.9 million in 2011. Tennessee was the leading ball clay producing state, with 63 percent of domestic production, followed by Texas, Mississippi, Kentucky and Indiana. Reported ball clay production from Indiana probably was fire clay rather than ball clay. About 69 percent of total ball clay production was airfloat, 20 percent was crude and 11 percent was water-slurried.

  3. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the fire clay industry, particularly in the U.S., as of June 2011. It claims that the leading fire clay producer in the U.S. is the state of Missouri. The other major producers include California, Texas and Washington. It reports that the use of heavy clay products made of fire clay like brick, cement and lightweight aggregate has increased slightly in 2010.

  4. Clays, common

    USGS Publications Warehouse

    Virta, R.L.

    1998-01-01

    Part of a special section on the state of industrial minerals in 1997. The state of the common clay industry worldwide for 1997 is discussed. Sales of common clay in the U.S. increased from 26.2 Mt in 1996 to an estimated 26.5 Mt in 1997. The amount of common clay and shale used to produce structural clay products in 1997 was estimated at 13.8 Mt.

  5. Clay Houses

    ERIC Educational Resources Information Center

    Pedro, Cathy

    2011-01-01

    In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

  6. A theoretical study on the advantage of core-shell particles with radially-oriented mesopores.

    PubMed

    Deridder, Sander; Catani, Martina; Cavazzini, Alberto; Desmet, Gert

    2016-07-22

    We report on a first-principles numerical study explaining the potential advantage of core-shell particles with strictly radially-oriented mesopores. Comparing the efficiency of these particles with fully porous and core-shell particles with a conventional (i.e., randomly oriented) mesopore network, the present numerical study shows a similar strong reduction in minimal reduced plate height (hmin) as was very recently observed in an experimental study by Wei et al. (respectively a hmin-reduction on the order of about 1 and 0.5 reduced plate height-units). As such, the present work provides a theoretical basis to understand and confirm their experimental findings and quantifies the general advantage of "radial-diffusion-only" particles. Determining the effective longitudinal diffusion (B-term contribution) in a series of dedicated, independent simulations, it was found that this contribution can be described by a very simple, yet fully exact mathematical expression for the case of "radial- diffusion-only" particles. Using this expression, the significant increase in efficiency of these particles can be fully attributed to their much smaller B-term band broadening, while their C-term band broadening (representing the mass transfer resistance) remains unaffected. PMID:27317003

  7. Deformation and orientation effects in heavy-particle radioactivity of Z=115

    NASA Astrophysics Data System (ADS)

    Sawhney, Gudveen; Sandhu, Kirandeep; Sharma, Manoj K.; Gupta, Raj K.

    2015-01-01

    The possibility of heavy particle radioactivity (heavier clusters) in ground state decays of 287-289115 parent nuclei, resulting in a doubly magic daughter around 208Pb is analyzed using Preformed Cluster Model (PCM) with choices of spherical and quadrupole deformation (β2) having "optimum" orientations of decay products. The behavior of fragmentation potential and preformation probability is investigated in order to extract better picture of the dynamics involved. Interestingly, the potential energy surfaces obtained via the fragmentation process get modified significantly with the inclusion of deformation and orientation effects, which in turn influence the preformation factor.

  8. Green Synthesis of Silver Nano-particles by Macrococcus bovicus and Its Immobilization onto Montmorillonite Clay for Antimicrobial Functionality.

    PubMed

    Abdel-Aziz, Mohamed S; Abou-El-Sherbini, Khaled S; Hamzawy, Esmat M A; Amr, Mohey H A; El-Dafrawy, Shady

    2015-08-01

    Macrococcus bovicus was locally isolated from soil and used in the green synthesis of nano-scaling silver (NSAg). It was immobilized on a sodic-montmorillonite clay (MMT1) and cetyltrimethylammonium bromide-modified montmorillonite (MMT2) which was also calcined at 300 °C (MMT3). The NSAg clays were characterized by X-ray fluorescence, Fourier transform infrared spectra, X-ray diffractometry, surface area measurement, UV-Vis spectrometry, scanning electron microscope, transmission electron microscope and thermogravimetric analysis. NSAg was confirmed to be included in the interparticular cavities of the clay sheets and its mechanical stability was evidenced. The antimicrobial activity of the NSAg-modified clays was investigated against Staphylococcus aureus, Escherichia coli and Candida albicans using the cup plate and the plate count techniques. The antimicrobial activity of the NSAg clays was confirmed and attributed to the caging of NSAg in MMT cavities. MMT3 was found to inhibit the microbial growth to as high as 65 % as observed from the plate count method. Graphical Abstract Scheme of the biosynthesis of nano-scaling Ag and its immobilization and antimicrobial application. PMID:26100387

  9. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Four companies mined fire clay in three states in 2012. Production, based on a preliminary survey of the fire clay industry, was estimated to be 230 kt (254,000 st) valued at $6.98 million, an increase from 215 kt (237,000 st) valued at $6.15 million in 2011. Missouri was the leading producing state, followed by Colorado and Texas, in decreasing order by quantity. The number of companies mining fire clay declined in 2012 because several common clay producers that occasionally mine fire clay indicated that they did not do so in 2012.

  10. Object-Oriented Parallel Particle-in-Cell Code for Beam Dynamics Simulation in Linear Accelerators

    SciTech Connect

    Qiang, J.; Ryne, R.D.; Habib, S.; Decky, V.

    1999-11-13

    In this paper, we present an object-oriented three-dimensional parallel particle-in-cell code for beam dynamics simulation in linear accelerators. A two-dimensional parallel domain decomposition approach is employed within a message passing programming paradigm along with a dynamic load balancing. Implementing object-oriented software design provides the code with better maintainability, reusability, and extensibility compared with conventional structure based code. This also helps to encapsulate the details of communications syntax. Performance tests on SGI/Cray T3E-900 and SGI Origin 2000 machines show good scalability of the object-oriented code. Some important features of this code also include employing symplectic integration with linear maps of external focusing elements and using z as the independent variable, typical in accelerators. A successful application was done to simulate beam transport through three superconducting sections in the APT linac design.

  11. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, May 9, 1992--August 8, 1992

    SciTech Connect

    Olson, E.S.

    1995-10-01

    An investigation of new methods for the production of mixed pillared clay catalysts and clay-supported catalysts and determination of their catalytic activities were continued in this quarter. To demonstrate the reproducibility of the preparative method for high activity iron/alumina-pillared montmorillonite catalysts, a new batch of the catalyst was prepared and tested for hydrocracking activity with bibenzyl. This preparation gave conversion and product distribution similar to that reported previously. The mixed iron/alumina-pillared clay was also prepared using a pillaring solution that was aged for longer period of time. To determine the importance of the type of pillaring support in hydrocracking activity, iron/zirconia-pillared montmorillonite was prepared using the same technique as that for iron/alumina-pillared montmorillonite. The reaction of bibenzyl with the sulfided iron/zirconia-pillared catalyst gave a lower hydrocracking conversion than the iron/alumina-pillared catalyst. Addition of a second catalytic metal to the clay support was attempted to determine if a synergistic effect could improve liquefaction. Ferric nitrate and stannous chloride were added to the clay, but the resulting catalyst was relatively poor for hydrocracking and hydrogenation compared with ferric nitrate supported on the clay. New disposable iron catalysts with high acidity and surface area are desired for coal liquefaction. Synthetic iron aluminosilicates were prepared by methods similar to those used for the nickel-substituted synthetic mica montmorillonite (NiSMM) catalysts, which are very effective for hydrogenation and reforming of hydrocarbons. The iron aluminosilicate catalysts were tested for hydrocracking and hydrogenation of bibenzyl, naphthalene and pyrene. Pyrene hydrogenation was effectively catalyzed by the sulfided synthetic iron catalyst.

  12. Stereological unfolding of the trivariate size-shape-orientation distribution of spheroidal particles with application

    SciTech Connect

    Benes, V.; Jiruse, M.; Slamova, M.

    1997-03-01

    A new stereological method is presented which enables the unfolding of joint size-shape-orientation distribution of spheroidal particles in opaque materials. It is shown that this trivariate problem can be decomposed into a series of two simpler problems. The sampling is based on a vertical uniform random planar section. Besides the theoretical integral equations between distributions of planar and spatial parameters, a numerical solution is also described in detail. The method is applied to the study of damage initiation in Al-Si metal matrix composites. Weibull modeling of particle cracking is briefly discussed.

  13. Orientation control of liquid crystals using carbon-nanotube-magnetic particle hybrid materials.

    PubMed

    Jeong, Hyeon Su; Youn, Sang Cheon; Kim, Yun Ho; Jung, Hee-Tae

    2013-06-28

    We have developed a simple yet versatile method for aligning liquid crystals (LCs) by using magnetic-field oriented single-walled carbon nanotubes (SWNTs) that were modified with magnetic particles. A high degree of homeotropic/planar LC alignment was achieved by SWNTs being exposed to a very low strength magnetic field, combined with strong π-π interactions between the biphenyl group in the LCs and the wall of the SWNTs. PMID:23676827

  14. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    In 2005, six companies mined fire clay in Missouri, Ohio and South Carolina. Production was estimate to be 300 kt with a value of $8.3 million. Missouri was the leading producer state followed by Ohio and South Carolina. For the third consecutive year, sales and use of fire clays have been relatively unchanged. For the next few years, sales of fire clay is forecasted to remain around 300 kt/a.

  15. Bayesian algorithms for recovering structure from single-particle diffraction snapshots of unknown orientation: a comparison

    SciTech Connect

    Moths, Brian; Ourmazd, Abbas

    2011-09-01

    X-ray free-electron lasers are being used to determine the three-dimensional structure of objects from random snapshots. The two apparently very different Bayesian algorithms capable of performing this at ultra-low signal are fundamentally the same. The advent of X-ray free-electron lasers promises the possibility to determine the structure of individual particles such as microcrystallites, viruses and biomolecules from single-shot diffraction snapshots obtained before the particle is destroyed by the intense femtosecond pulse. This program requires the ability to determine the orientation of the particle giving rise to each snapshot at signal levels as low as ~10{sup −2} photons per pixel. Two apparently different approaches have recently demonstrated this capability. Here we show they represent different implementations of the same fundamental approach, and identify the primary factors limiting their performance.

  16. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The state of the ball clay industry in 1999 is presented. Record highs in the sales and use of ball clay were attained in 1999 due to the continued strength of the U.S. economy. U.S. production was estimated at 1.25 million st for the year, with more than half of that amount mined in Tennessee. Details of the consumption, price, imports, and exports of ball clay in 1999 and the outlook for ball clay over the next few years are provided.

  17. Electro-phoretic rotation and orientation of polarizable spheroidal particles in AC fields

    NASA Astrophysics Data System (ADS)

    Miloh, Touvia; Goldstein, Ben Weis

    2015-02-01

    A theoretical study is provided for determining the angular rotation rate of an ideally polarized (metallic) spheroidal particle freely suspended in a symmetric electrolyte under general alternating current ambient electric excitations. In particular, we discuss cases of electro-rotation (ROT) and electro-orientation (EOR) of such nano/micro particles incited by two orthogonal electric field components which may be out of phase. The analysis is carried under the Poisson-Nernst-Planck approximation and the "weak" field model. The analytic expressions thus obtained are valid for a conducting prolate spheroid with arbitrary eccentricity including the limiting cases of isotropic spheres and infinitely long cylindrical rods. The total dipolophoretic (DIP) angular velocity is decomposed from contributions due to dielectrophoresis (DEP) induced by the dipole-moment within the particle and by the induced-charge electrophoresis (ICEP) mechanism near the conducting surface. It is demonstrated that the explicit expressions for the DIP angular velocities reduce to the well-known ROT solution for the sphere as well as to the recently found expressions (based on slender-body approximation) for both ROT and EOR of metal nanowires [Arcenegui et al., "Electro-orientation and electrorotation of metal nanowires," Phys. Rev. E 88(6), 063018 (2013)]. Some comparisons with available experimental data are also provided for slender spheroidal geometries including a detailed discussion of DEP and ICEP effects and their relative contributions to the overall DIP rotational velocity.

  18. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, November 9, 1992--February 8, 1993

    SciTech Connect

    Olson, E.S.

    1995-10-01

    The mixed iron/alumina pillared clay catalysts and clay-supported iron catalysts have been shown in previous reports of this project to significantly improve yields of heptane-soluble products obtained in the liquefaction of both as received and acid-exchanged Wyodak subbituminous coal and Blind Canyon bituminous coal. In this quarter, the soluble product (LSW) obtained from the noncatalytic low-severity liquefaction of Wyodak coal was used as a feed to determine the activity of iron based catalysts for the hydrogenation and depolymerization steps. Comparison data for liquefaction of the soluble LSW with other catalysts were desired, and these data were obtained for a dispersed form of iron sulfide, prepared via iron hydroxyoxide (PETC method). The iron oxyhydroxide catalyst was directly precipitated on LSW product using either water or ethanol as the solvent. An insight into the functioning of the mixed iron/alumina pillared clay in coal liquefaction was investigated by preparing and studying an iron oxoaluminate structure. An investigation of new methods for the production of tetralin soluble iron oxometallate catalysts and the determination of their catalytic activities was continued in this quarter. The hydrogenation activity of iron oxoaluminate was investigated using pyrene and 1-methylnaphthalene as the test compounds, and results were compared with thermal reactions. In order to determine the loss of activity, recovered catalyst was recycled a second time for the hydrotreating of pyrene. Reaction of 1-methylnaphthalene with iron oxoaluminate also gave very high conversion to 1- and 5-methyltetralins and small amount of 2- and 6-methyltetralins. Liquefaction of Wyodak subbituminous and Blind Canyon bituminous coal was investigated using an in situ sulfided soluble iron oxoaluminate catalyst.

  19. Detection of preferential particle orientation in the atmosphere. Development of an alternative polarization lidar system

    SciTech Connect

    Geier, Manfred; Arienti, Marco

    2014-07-19

    Increasing interest in polarimetric characterization of atmospheric aerosols has led to the development of complete sample-measuring (Mueller) polarimeters that are capable of measuring the entire backscattering phase matrix of a probed volume. The Mueller polarimeters consist of several moving parts, which limit measurement rates and complicate data analysis. In this paper, we present the concept of a less complex polarization lidar setup for detection of preferential orientation of atmospheric particulates. On the basis of theoretical considerations of data inversion stability and propagation of measurement uncertainties, an optimum optical configuration is established for two modes of operation (with either a linear or a circular polarized incident laser beam). We discovered that the conceptualized setup falls in the category of incomplete sample-measuring polarimeters and uses four detection channels for simultaneous measurement of the backscattered light. Likewise, the expected performance characteristics are discussed through an example of a typical aerosol with a small fraction of particles oriented in a preferred direction. As a result, the theoretical analysis suggests that achievable accuracies in backscatter cross-sections and depolarization ratios are similar to those with conventional two-channel configurations, while in addition preferential orientation can be detected with the proposed four-channel system for a wide range of conditions.

  20. Detection of preferential particle orientation in the atmosphere. Development of an alternative polarization lidar system

    DOE PAGESBeta

    Geier, Manfred; Arienti, Marco

    2014-07-19

    Increasing interest in polarimetric characterization of atmospheric aerosols has led to the development of complete sample-measuring (Mueller) polarimeters that are capable of measuring the entire backscattering phase matrix of a probed volume. The Mueller polarimeters consist of several moving parts, which limit measurement rates and complicate data analysis. In this paper, we present the concept of a less complex polarization lidar setup for detection of preferential orientation of atmospheric particulates. On the basis of theoretical considerations of data inversion stability and propagation of measurement uncertainties, an optimum optical configuration is established for two modes of operation (with either a linearmore » or a circular polarized incident laser beam). We discovered that the conceptualized setup falls in the category of incomplete sample-measuring polarimeters and uses four detection channels for simultaneous measurement of the backscattered light. Likewise, the expected performance characteristics are discussed through an example of a typical aerosol with a small fraction of particles oriented in a preferred direction. As a result, the theoretical analysis suggests that achievable accuracies in backscatter cross-sections and depolarization ratios are similar to those with conventional two-channel configurations, while in addition preferential orientation can be detected with the proposed four-channel system for a wide range of conditions.« less

  1. Defects, Entropy, and the Stabilization of Alternative Phase Boundary Orientations in Battery Electrode Particles

    DOE PAGESBeta

    Heo, Tae Wook; Tang, Ming; Chen, Long-Qing; Wood, Brandon C.

    2016-01-04

    Using a novel statistical approach that efficiently explores the space of possible defect configurations, our present study investigates the chemomechanical coupling between interfacial structural defects and phase boundary alignments within phase-separating electrode particles. Applied to the battery cathode material LiXFePO4 as an example, the theoretical analysis reveals that small, defect-induced deviations from an ideal interface can lead to dramatic shifts in the orientations of phase boundaries between Li-rich and Li-lean phases, stabilizing otherwise unfavorable orientations. Significantly, this stabilization arises predominantly from configurational entropic factors associated with the presence of the interfacial defects rather than from absolute energetic considerations. The specificmore » entropic factors pertain to the diversity of defect configurations and their contributions to rotational/orientational rigidity of phase boundaries. Comparison of the predictions with experimental observations indicates that the additional entropy contributions indeed play a dominant role under actual cycling conditions, leading to the conclusion that interfacial defects must be considered when analyzing the stability and evolution kinetics of the internal phase microstructure of strongly phase-separating systems. Possible implications for tuning the kinetics of (de)lithiation based on selective defect incorporation are discussed. Ultimately, this understanding can be generalized to the chemomechanics of other defective solid phase boundaries.« less

  2. Orientational kinetics of dipolar particles in a Maxwell fluid matrix: inertialess limit for the rotary microrheology.

    PubMed

    Raikher, Yu L; Rusakov, V V

    2005-12-01

    We study magnetic response of an assembly of ferroparticles suspended in a viscoelastic matrix which is modeled by a Maxwell fluid with a unique stress relaxation time. The problem refers to the magnetic microrheology approach where deformational properties of a complex fluid are tested with the aid of embedded nanoparticle probes set to motion by an external ac magnetic field. A possibility is considered to simplify the description of the orientational kinetics of the system at the expense of neglecting inertia effects in particle rotary motion. It is shown that in this aspect a Maxwell matrix differs essentially from the Newtonian one. In the latter the inertialess approximation for the particles of the approximately 10nm size is valid practically unboundedly. For a viscoelastic matrix the inertialess approximation means an important restriction on the value of the stress relaxation time. Assuming weak nonequilibrium, the magneto-orientational relaxation times are found and low-frequency magnetic spectra of a viscoelastic suspension are determined in the presence of a constant (magnetizing) field. PMID:16485946

  3. Angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei

    SciTech Connect

    Severijns, N.; Golovko, V.V.; Kraev, I.S.; Phalet, T.; Belyaev, A.A.; Lukhanin, A.A.; Noga, V.I.; Erzinkyan, A.L.; Parfenova, V.P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V.T.; Toporov, Yu.G.; Zotov, E.; Gurevich, G.M.; Rusakov, A.V.; Vyachin, V.N.; Zakoucky, D.

    2005-04-01

    The anisotropy in the angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei, which are among the strongest deformed {alpha} emitters, was measured. Large {alpha} anisotropies have been observed for all three nuclei. The results are compared with calculations based on {alpha}-particle tunneling through a deformed Coulomb barrier.

  4. Mechanisms behind injecting the combination of nano-clay particles and polymer solution for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Khalili Nezhad, Seyyed Shahram; Cheraghian, Goshtasp

    2015-09-01

    Laboratory investigations and field applications have proved injection of polymer solution to be an effective means to improve oil recovery for reservoirs of medium oil viscosity. The incremental oil produced in this case is the result of an increase in areal and vertical sweep efficiencies. Biopolymers and synthetic polymers are the major categories used in the petroleum industry for specific reasons. Biopolymers like xanthan are limited in their application as they are more susceptible to biodegradation. Synthetic polymers like Hydrolyzed PolyAcrylaMide (HPAM) have a much wider application as they are less susceptible to biodegradation. Furthermore, development of nanotechnology has successfully provided technical and economical viable alternatives for present materials. The objective of this study is to investigate the effect of combining clay nanoparticles with polymer solution on oil recovery. This paper includes a history match of both one-dimensional and two-dimensional polymer floods using a three-dimensional numerical model for fluid flow and mass transport. Results indicated that the amount of polymer adsorption decreased when clay nanoparticles were added to the PolyAcrylaMide solution; however, mobility ratio improvement is believed to be the main contributor for the proposed method in order to enhance much oil recovery compared to xanthan flood and HPAM flood.

  5. Mechanisms behind injecting the combination of nano-clay particles and polymer solution for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Khalili Nezhad, Seyyed Shahram; Cheraghian, Goshtasp

    2016-08-01

    Laboratory investigations and field applications have proved injection of polymer solution to be an effective means to improve oil recovery for reservoirs of medium oil viscosity. The incremental oil produced in this case is the result of an increase in areal and vertical sweep efficiencies. Biopolymers and synthetic polymers are the major categories used in the petroleum industry for specific reasons. Biopolymers like xanthan are limited in their application as they are more susceptible to biodegradation. Synthetic polymers like Hydrolyzed PolyAcrylaMide (HPAM) have a much wider application as they are less susceptible to biodegradation. Furthermore, development of nanotechnology has successfully provided technical and economical viable alternatives for present materials. The objective of this study is to investigate the effect of combining clay nanoparticles with polymer solution on oil recovery. This paper includes a history match of both one-dimensional and two-dimensional polymer floods using a three-dimensional numerical model for fluid flow and mass transport. Results indicated that the amount of polymer adsorption decreased when clay nanoparticles were added to the PolyAcrylaMide solution; however, mobility ratio improvement is believed to be the main contributor for the proposed method in order to enhance much oil recovery compared to xanthan flood and HPAM flood.

  6. Preferred orientation of phyllosilicates: Effects of composition and stress on resedimented mudstone microfabrics

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, Ruarri J.; Schleicher, Anja M.; Schneider, Julia; Flemings, Peter B.; Germaine, John T.; van der Pluijm, Ben A.

    2011-09-01

    Development of a preferred orientation of clay minerals is investigated in response to changes in vertical effective stress and composition in resedimented material (Boston Blue Clay). Boston Blue Clay (BBC), an illitic glacio-marine clay composed of 57% clay-sized particles (<2 μm) was resedimented and step-loaded to a vertical effective stress of 0.1 MPa, 1 MPa, 6 MPa, and 10 MPa. These four samples show a small increase in preferred orientation of mica and chlorite with increasing vertical effective stress. Furthermore, pure BBC powder was admixed with silica (silt-sized quartz) in five different ratios of BBC:silica to form sediments with 57%, 52%, 48%, 44%, and 36% < 2 μm particles and were loaded to a maximum vertical effective stress of 2.4 MPa. Mica preferred orientation decreases significantly with decreasing clay content at one stress state. We used and compared three different techniques to characterize and quantify the preferred orientation of phyllosilicates: transmission-mode X-ray texture goniometry, reflection-mode X-ray texture goniometry, and grain and pore networks imaged using secondary and backscattered electron micrographs gathered on argon-ion-milled surfaces. Preferred orientation of the clay minerals shows good agreement between transmission-mode X-ray texture goniometry and reflection-mode X-ray texture goniometry. Mercury porosimetry further illuminates vertical effective stress and compositional controls on microfabric.

  7. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Five companies mined fire clay in four states in 2011. Production, based on a preliminary survey of the fire clay industry, was estimated to be 240 kt (265,000 st), valued at $7.68 million, an increase from 216 kt (238,000 st), valued at $6.12 million in 2010. Missouri was the leading producing state, followed by Texas, Washington and Ohio, in decreasing order by quantity.

  8. UV/visible and surface-enhanced infrared studies of polyethylene/oriented gold nanoparticle composite films: The effects of gold particle size, shape, and orientation

    NASA Astrophysics Data System (ADS)

    Al-Rawashdeh, Nathir A. F.

    We have succeeded in preparing gold rods of high aspect ratio (>6) and diameter ca. ≈32 nm, using anodically grown alumina films as host templates. To evaluate the sample quality, the plasmon resonance spectra of alumina/gold nanoparticle composite films were measured. In general, we found that the plasmon resonance maxima and intensity are dependent on the size, shape, and orientation of the gold nanoparticle. Furthermore, we have succeeded in orienting such nanoparticles in polyethylene matrices, and confirmed the net orientation via polarization studies in the UV/Visible/Near-IR region of the spectrum. In the polarization studies, we found that the extent of red-shift and damping of the plasmon resonance band are dependent on the size, shape, and orientation of the gold nanoparticle. The effects of gold particle size, shape, and orientation on the plasmon resonance spectra of polyethylene/oriented gold particle composite films have been compared to the predictions of Rayleigh scattering theory and effective medium theories (Maxwell-Garnett (MG) and Bruggeman (BRG)). From the comparison of the experimental plasmon resonance spectra with the calculated spectra using the above theories, we found that the best model for predicting the experimental plasmon resonance band shape and intensity is the BRG treatment. That finding has implications for what the sample is like. After we confirmed the net orientation of the nanoparticles in polyethylene matrices, we examined the infrared-transmittance spectra of 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) chemically bonded on such composite films via polarization studies. In general, we found that the IR-transmittance spectra of MPA and MUA show a polarization angle dependence. We discuss the effects of the gold particle shape, and orientation in the incident field on electromagnetic (EM) enhancements as seen in our oriented gold rod composite studies, in the context of the effective medium type

  9. A self-adaptive oriented particles Level-Set method for tracking interfaces

    NASA Astrophysics Data System (ADS)

    Ianniello, S.; Di Mascio, A.

    2010-02-01

    A new method for tracking evolving interfaces by lagrangian particles in conjunction with a Level-Set approach is introduced. This numerical technique is based on the use of time evolution equations for fundamental vector and tensor quantities defined on the front and represents a new and convenient way to couple the advantages of the Eulerian description given by a Level-Set function ϕ to the use of Lagrangian massless particles. The term oriented points out that the information advected by the particles not only concern the spatial location, but also the local (outward) normal vector n to the interface Γ and the second fundamental tensor (the shape operator) ∇n. The particles are exactly located upon Γ and provide all the requested information for tracking the interface on their own. In addition, a self-adaptive mechanism suitably modifies, at each time step, the markers distribution in the numerical domain: each particle behaves both as a potential seeder of new markers on Γ (so as to guarantee an accurate reconstruction of the interface) and a de-seeder (to avoid any useless gathering of markers and to limit the computational effort). The algorithm is conceived to avoid any transport equation for ϕ and to confine the Level-Set function to the role of a mere post-processing tool; thus, all the numerical diffusion problems usually affecting the Level-Set methodology are removed. The method has been tested both on 2D and 3D configurations; it carries out a fast reconstruction of the interface and its accuracy is only limited by the spatial resolution of the mesh.

  10. Turbulent coagulation of particles smaller than the length scales of turbulence and equilibrium sorption of phenanthrene to clay: Implications for pollutant transport in the estuarine water column

    NASA Astrophysics Data System (ADS)

    Brunk, Brett Kenneth

    1997-11-01

    Pollutant and particle transport in estuaries is affected by a multitude of physical, chemical and biological processes. In this research the importance of equilibrium sorption and turbulent coagulation were studied. Sorption in estuaries was modeled using phenanthrene, bacterial extracellular polymer and kaolinite clay as surrogates for a hydrophobic organic pollutant, dissolved organic matter and inorganic suspended sediment, respectively. Experiments over a range of estuarine salinities showed that ionic strength had the largest effect on the extent of sorption, while the effect of extracellular polymer coatings on the mineral surfaces was insignificant. Further calculations using typical estuarine suspended sediment concentrations indicated that equilibrium sorption could not fully account for the solid/solution phase distribution of hydrophobic organic compounds in the estuarine water column. For particles that are small compared to the length scales of turbulence, the rate of coagulation is related to the dynamics of the smallest turbulent eddies since they have the highest shear rate. Experimental and theoretical effort focused on determining the coagulation rate of spherical particles in isotropic turbulence. A pair diffusion approximation valid for rapidly fluctuating flows was used to calculate the rate of coagulation in a randomly varying isotropic linear flow field. Dynamic simulations of particle coagulation in Gaussian turbulence were computed over a range of representative values of particle-particle interactions (i.e, hydrodynamic interactions and van der Waals attraction) and total strain (i.e., the product of the strain rate and its time scale). The computed coagulation rates for isotropic turbulence differed from analytical approximations valid at large and small total strain. As expected, particle interactions were found to be significant. Experimental measurements of coagulation in grid-generated turbulence were obtained by measuring the loss

  11. Obtaining Approximate Values of Exterior Orientation Elements of Multi-Intersection Images Using Particle Swarm Optimization

    NASA Astrophysics Data System (ADS)

    Li, X.; Li, S. W.

    2012-07-01

    In this paper, an efficient global optimization algorithm in the field of artificial intelligence, named Particle Swarm Optimization (PSO), is introduced into close range photogrammetric data processing. PSO can be applied to obtain the approximate values of exterior orientation elements under the condition that multi-intersection photography and a small portable plane control frame are used. PSO, put forward by an American social psychologist J. Kennedy and an electrical engineer R.C. Eberhart, is a stochastic global optimization method based on swarm intelligence, which was inspired by social behavior of bird flocking or fish schooling. The strategy of obtaining the approximate values of exterior orientation elements using PSO is as follows: in terms of image coordinate observed values and space coordinates of few control points, the equations of calculating the image coordinate residual errors can be given. The sum of absolute value of each image coordinate is minimized to be the objective function. The difference between image coordinate observed value and the image coordinate computed through collinear condition equation is defined as the image coordinate residual error. Firstly a gross area of exterior orientation elements is given, and then the adjustment of other parameters is made to get the particles fly in the gross area. After iterative computation for certain times, the satisfied approximate values of exterior orientation elements are obtained. By doing so, the procedures like positioning and measuring space control points in close range photogrammetry can be avoided. Obviously, this method can improve the surveying efficiency greatly and at the same time can decrease the surveying cost. And during such a process, only one small portable control frame with a couple of control points is employed, and there are no strict requirements for the space distribution of control points. In order to verify the effectiveness of this algorithm, two experiments are

  12. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, February 9, 1993--May 8, 1993

    SciTech Connect

    Olson, E.S.

    1995-10-01

    An investigation of new methods for the production and utilization of tetralin-soluble iron oxometallate precursors for coal liquefaction catalysts was continued in this quarter. Further descriptions of the catalytic activities of the sulfided forms were obtained. The hydrogenation activities of catalysts derived from iron oxotitanate and cobalt oxoaluminate were investigated using pyrene as a the test compound, and results were compared with thermal reactions. The hydrogenation activity of iron oxotitanate was superior to other catalysts including iron oxoaluminate. The hydrogenation activity of cobalt oxoaluminate was similar to that of iron oxoaluminate reported in previous quarterly report. The liquefaction of Wyodak subbituminous coal was investigated using in situ sulfided iron oxotitanate catalyst. In order to improve the usefulness of iron oxoaluminate as a liquefaction catalyst, iron oxoaluminate was supported on acid-treated montmorillonite (K-10). Supporting the iron oxoaluminate on an acidic support significantly improved the hydrogenation activity of iron oxoaluminate. The hydrocracking activity was increased by a large factor. Thus the aluminate and titanate structures surrounding the pyrrhotite that forms during sulfidation have a beneficial effect in preventing deactivation of the iron sites, and the presence of the acidic sites in the clay results in effective catalytic synergism between catalyst and support. These clay-supported iron oxometallates are highly promising catalysts for coal liquefaction. Iron oxyhydroxide and triiron supported on acid-treated montmorillonite (K-10) were tested for the liquefaction of ion-exchanged Wyodak (IEW) to minimize effects of the coal mineral matter. Both sulfided catalysts gave very high conversions of coal to THF-soluble and heptane-soluble (oils) products.

  13. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Four companies — H.C. Spinks Clay Co., Inc., Imerys Group, Old Hickory Clay Co., and Unimin Corp. — mined ball clay in four states in 2011. Production, on the basis of preliminary data, was 940 kt (1.04 million st) with an estimated value of $44.2 million. This is a 3-percent increase in tonnage from 912 kt (1.01 million st) with a value of $41.3 million that was produced in 2010. Tennessee was the leading producing state with 63 percent of domestic production, followed by Texas, Mississippi and Kentucky. About 69 percent of production was airfloat, 20 percent was crude and 11 percent was water-slurried.

  14. Rheological behavior of clay-nanoparticle hybrid-added bentonite suspensions: specific role of hybrid additives on the gelation of clay-based fluids.

    PubMed

    Jung, Youngsoo; Son, You-Hwan; Lee, Jung-Kun; Phuoc, Tran X; Soong, Yee; Chyu, Minking K

    2011-09-01

    Two different types of clay nanoparticle hybrid, iron oxide nanoparticle clay hybrid (ICH) and Al(2)O(3)-SiO(2) nanoparticle clay hybrid (ASCH), were synthesized and their effects on the rheological properties of aqueous bentonite fluids in steady state and dynamic state were explored. When ICH particles were added, bentonite particles in the fluid cross-link to form relatively well-oriented porous structure. This is attributed to the development of positively charged edge surfaces in ICH that leads to strengthening of the gel structure of the bentonite susensions. The role of ASCH particles on the interparticle association of the bentonite fluids is different from that of ICH and sensitive to pH. As pH of ASCH-added bentonite suspensions increased, the viscosity, yield stress, storage modulus, and flow stress decreased. In contrast, at low pH, the clay suspensions containing ASCH additives were coagulated and their rheological properties become close to those of ICH added bentonite fluids. A correlation between the net surface charge of the hybrid additives and the rheological properties of the fluids indicates that the embedded nanoparticles within the interlayer space control the variable charge of the edge surfaces of the platelets and determine the particles association behavior of the clay fluids. PMID:21888313

  15. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, May 8, 1993--August 8, 1993

    SciTech Connect

    Olson, E.S.

    1995-10-01

    High hydrocracking and liquefaction activity can be achieved with 10 wt.% of sulfided clay-supported iron catalysts. Further tests and demonstrations of this activity were required. Iron hydroxyoxide was generated on acid-treated montmorillonite. The new batch of catalyst exhibited high hydrocracking activity, Three hour tests with the solubilized intermediate from low-severity treatment of Wyodak coal (LSW) gave a high conversion (45%) of the heptane-insoluble LSW intermediate to heptane-soluble products. An investigation of new methods for the production of catalysts from tetralin-soluble iron oxometallates and the determination of their catalytic activities was continued in this quarter. Iron oxotitanate and iron oxoaluminate gave very high conversions of LSW to heptane solubles (61% and 54%, respectively). The high yields of heptane soluble products obtained with these catalysts offers a potential for use in liquefaction stages with solubilized coal, or at least serve as a model for producing active catalysts via mixed metal oxides. Methods for successfully testing dispersed iron catalysts with the low-severity intermediate were also devised. Catalyst recovered from the dispersed iron hydroxyoxide-catalyzed reaction of ion-exchanged Wyodak gave a high conversion (47%) of LSW to heptane solubles.

  16. Acoustic metafluid with anisotropic mass density and tunable sound speed: An approach based on suspensions of orientable anisotropic particles

    NASA Astrophysics Data System (ADS)

    Seitel, Mark; Tse, Stephen; Shan, Jerry

    2011-11-01

    We investigate liquid suspensions of micron-scale, anisotropic particles as potential acoustic metafluids having anisotropic and actively controllable acoustic properties. The effective mass density (and hence the sound propagation speed) of these metafluids can vary because the added mass of an anisotropic particle suspended in the fluid changes with the particle's orientation relative to the direction of the wave propagation. A suspension with disc-like particles oriented broadside to the direction of wave propagation is thus expected to have higher effective inertia and lower sound speed than a suspension with particles with end-on alignment. To test these predictions, sound speed is measured with a time-of-flight method in suspensions of micron-size nickel flakes suspended in oil, with and without magnetic-field-induced alignment of the particles. The sound speed, relative to the unaligned case, is found to decrease for particles oriented broadside to the sound wave, and increase for edgewise alignment. We also investigate the frequency dependence of the effective sound speed, since the added mass effect is expected to diminish as the flow becomes steady at low frequencies. The experimental results are compared to the predictions of a model proposed by Ahuja & Hardee (J. Acoust. Soc. Am 1978) for the acoustic properties of aligned oblate-spheroid suspensions.

  17. Coherent diffraction of a single virus particle: The impact of a water layer on the available orientational information

    SciTech Connect

    Wang, F.; Weckert, E.; Ziaja, B.; Larsson, D. S. D.; Spoel, D. van der

    2011-03-15

    Coherent diffractive imaging using x-ray free-electron lasers (XFELs) may provide a unique opportunity for high-resolution structural analysis of single particles sprayed from an aqueous solution into the laser beam. As a result, diffraction images are measured from randomly oriented objects covered by a water layer. We analyze theoretically how the thickness of the covering water layer influences the structural and orientational information contained in the recorded diffraction images. This study has implications for planned experiments on single-particle imaging with XFELs.

  18. Electric alignment of plate shaped clay aggregates in oils

    NASA Astrophysics Data System (ADS)

    Castberg, Rene; Rozynek, Zbigniew; Måløy, Knut Jørgen; Flekkøy, Eirik

    2016-01-01

    We experimentally investigate the rotation of plate shaped aggregates of clay mineral particles immersed in silicone oil. The rotation is induced by an external electric field. The rotation time is measured as a function of the following parameters: electric field strength, the plate geometry (length and width) and the dielectric properties of the plates. We find that the plates always align with their longest axis parallel to the direction of the electric field (E), independently of the arrangement of individual clay ‑2 mineral particles within the plate. The rotation time is found to scale as E and is proportional to the viscosity (μ), which coincides well with a model that describes orientation of dipoles in electric fields. As the length of the plate is increased we quantify a difference between the longitudinal and transverse polarisability. Finally, we show that moist plates align faster. We attribute this to the change of the dielectric properties of the plate due to the presence of water.

  19. Platelet-like hexagonal SrFe12O19 particles: Hydrothermal synthesis and their orientation in a magnetic field

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Peng, Xiaoling; Li, Jing; Yang, Yanting; Xu, Jingcai; Wang, Panfeng; Jin, Dingfeng; Jin, Hongxiao; Hong, Bo; Wang, Xinqing; Ge, Hongliang

    2016-08-01

    Platelet-like hexagonal SrFe12O19 particles were prepared by hydrothermal synthesis, and the effects of molar ratio of Fe/Sr (RFe/Sr) on the phase compositions, morphologies and magnetic properties of as-prepared samples were investigated. The optimum RFe/Sr is identified as 8:1. The hexagonal platelet-like particles are nano-scale in thickness and micro-scale in diameter. The low coercivity is a consequence of the large shape anisotropy of the as-synthesized particles. The platelet-like hexagonal SrFe12O19 particles were then dispersed in epoxy resin and formed ordered arrangement structure which took root in the curing epoxy matrix under an external magnetic field of 8000 Oe. The microstructures, morphologies and magnetic properties of the bulk samples orientated and nonaligned were studied. The platelet-like particles arrange with the platelet perpendicular to the magnetic field direction in the orientated samples. This demonstrates that the easy axis of the particle is perpendicular to the platelet, and that the magnetocrystalline anisotropy still plays a leading role in the changing effective anisotropy with the rapidly growing shape anisotropy. The remanence (Mr) of the bulk samples is changed obviously after orientation, while the coercivity nearly remains constant. That is, the maximum energy products (BH)max can be effectively adjusted by given a suitable magnetic field.

  20. Clay-based Nanocomposites Possibilities and Limitations

    NASA Astrophysics Data System (ADS)

    Papoulis, Dimitris

    2011-09-01

    In the last decades, clay mineral based nanocomposites and polymer-clay nanocomposites (PCNC) have been proposed as very useful materials for many uses including photocatalysis, medicinal uses as tissue engineering or modified drug delivery systems. Clay minerals and especially montmorillonite, kaolinite, halloysite palygorskite and sepiolite are the most used clay minerals because of their high surface areas, colloidal dimensions of their particles and other properties. This lecture aims at reporting on very recent developments in the use of clay minerals and PCNC as materials with photocatalytic and medical interest.

  1. Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sevilla, Paloma; Labrador-Páez, Lucía; Wawrzyńczyk, Dominika; Nyk, Marcin; Samoć, Marek; Kar, Ajoy Kumar; MacKenzie, Mark D.; Paterson, Lynn; Jaque, Daniel; Haro-González, Patricia

    2015-12-01

    An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er3+,Yb3+ upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as the relative orientation between optical traps. All these results show the possibility of real time three-dimensional manipulation and tracking of anisotropic nanoparticles with wide potential application in modern nanobiophotonics.An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er3+,Yb3+ upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as

  2. Clay Swelling and Particle Redistribution in a Saw-Cut Fracture in the Paintbrush Nonwelded Unit of the Topopah Spring Tuff

    NASA Astrophysics Data System (ADS)

    Kneafsey, T. J.; Oldenburg, C. M.; Salve, R.

    2001-12-01

    Flow through the altered nonwelded tuffs of the Paintbrush unit (PTn) at Yucca Mountain, Nevada, is thought to be primarily through the highly porous rock matrix. Due to matrix flow and the sloping structure of the unit, the PTn is thought to divert downward-flowing water laterally. However, large fractures and faults in the PTn may also provide pathways for flow through the unit and these may prevent or interrupt lateral flow through the unit. In field tests where water was released directly into a fault in the altered PTn, flow rates declined over time. To evaluate processes such as matrix swelling and particle redistribution that might explain this decline, we performed a laboratory experiment using a 12 cm diameter x 21.6 cm long core with an axial saw-cut fracture. The core was extracted from the argillic Tpbt2C layer. We monitored permeability, inlet and outlet flow rate, and the volume change of the rock core (contained in a pressure vessel) while flow occurred through the fracture and matrix. Water containing various sodium chloride concentrations (1 M, 0.5 M, 0 M, and 1M) was flowed through the fracture to observe the effect of salt concentration on fracture permeability in the smectite-rich rock core. The sample swelled initially, despite the high salt concentration (1 M) of the inlet water. The permeability of the fracture decreased with declining salt concentration and increased with increasing salt concentration indicating that clay swelling decreased fracture aperture and reduced the flow rate. Particle redistribution (dispersion and flocculation) was indicated by particles in the effluent. Particles from lower salinity flows remained suspended in the effluent container, while those from higher salinity flows settled more easily, were larger, and more compact. If particle redistribution were controlling the flow, the permeability should have increased during low salinity water flow because of particle erosion. This work was supported by the Director

  3. Clay for Little Fingers.

    ERIC Educational Resources Information Center

    Koster, Joan Bouza

    1999-01-01

    Discusses the renewed interest in clay as a modeling compound in early childhood programs; describes the nature of clay and presents a working vocabulary. Suggests methods of working with clay, including introducing clay to children, discovering its uses, clean up, firing clay, and finishing baked clay. Includes activity suggestions and…

  4. Potassium hydroxide clay stabilization process

    SciTech Connect

    Sydansk, R.

    1981-07-28

    An aqueous solution having potassium hydroxide dissolved therein is injected into a subterranean sandstone formation containing water-sensitive fine particles, including clays. Potassium hydroxide stabilizes the fine particles for a substantial period of time thereby substantially preventing formation permeability damage caused by encroachment of aqueous solutions having a distinct ionic makeup into the treated formation.

  5. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Seven companies mined fire clay in four states during 2003. From 1984 to 1992, production declined to 383 kt (422,000 st) from a high of 1.04 Mt (1.14 million st) as markets for clay-based refractories declined. Since 1992, production levels have been erratic, ranging from 383 kt (422,000 st) in 1992 and 2001 to 583 kt (642,000 st) in 1995. Production in 2003, based on preliminary data, was estimated to be around 450 kt (496,000 st) with a value of about $10.5 million. This was about the same as in 2002. Missouri remained the leading producer state, followed by South Carolina, Ohio and California.

  6. Modelling of the physico-chemical behaviour of clay minerals with a thermo-kinetic model taking into account particles morphology in compacted material.

    NASA Astrophysics Data System (ADS)

    Sali, D.; Fritz, B.; Clément, C.; Michau, N.

    2003-04-01

    Modelling of fluid-mineral interactions is largely used in Earth Sciences studies to better understand the involved physicochemical processes and their long-term effect on the materials behaviour. Numerical models simplify the processes but try to preserve their main characteristics. Therefore the modelling results strongly depend on the data quality describing initial physicochemical conditions for rock materials, fluids and gases, and on the realistic way of processes representations. The current geo-chemical models do not well take into account rock porosity and permeability and the particle morphology of clay minerals. In compacted materials like those considered as barriers in waste repositories, low permeability rocks like mudstones or compacted powders will be used : they contain mainly fine particles and the geochemical models used for predicting their interactions with fluids tend to misjudge their surface areas, which are fundamental parameters in kinetic modelling. The purpose of this study was to improve how to take into account the particles morphology in the thermo-kinetic code KINDIS and the reactive transport code KIRMAT. A new function was integrated in these codes, considering the reaction surface area as a volume depending parameter and the calculated evolution of the mass balance in the system was coupled with the evolution of reactive surface areas. We made application exercises for numerical validation of these new versions of the codes and the results were compared with those of the pre-existing thermo-kinetic code KINDIS. Several points are highlighted. Taking into account reactive surface area evolution during simulation modifies the predicted mass transfers related to fluid-minerals interactions. Different secondary mineral phases are also observed during modelling. The evolution of the reactive surface parameter helps to solve the competition effects between different phases present in the system which are all able to fix the chemical

  7. Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy.

    PubMed

    Rodríguez-Sevilla, Paloma; Labrador-Páez, Lucía; Wawrzyńczyk, Dominika; Nyk, Marcin; Samoć, Marek; Kar, Ajoy Kumar; Mackenzie, Mark D; Paterson, Lynn; Jaque, Daniel; Haro-González, Patricia

    2016-01-01

    An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er(3+),Yb(3+) upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as the relative orientation between optical traps. All these results show the possibility of real time three-dimensional manipulation and tracking of anisotropic nanoparticles with wide potential application in modern nanobiophotonics. PMID:26607763

  8. Tensile and burning properties of clay/phenolic/GF composite and its application

    NASA Astrophysics Data System (ADS)

    Diharjo, Kuncoro; Armunanto, V. Bram; Kristiawan, S. Adi

    2016-03-01

    Composite material has been widely used in automotive due to its properties can be improved by combining with reinforcement, like fiber and particle to enhance mechanical properties and burning resistance. This study aims to investigate the tensile and burning properties of hybrid composite combining glass fiber and clay in phenolic resin. The clay was produced from roof tile rejected by tile industries in Sokka, Kebumen, Indonesia. The composite was made using a press mold method for different number of laminates and orientation of woven-roving-glass-fiber/ WRGF (0/90 and ±45), and the total volume fraction of fiber and clay is constant 40%. The specimens were tested using universal testing machine for tensile properties and burning tests apparatus for burning resistance (time to ignite/ TTI and burning rate/ BR). The enhancing of the Clay/Penolic/GF composite can be performed by the increasing of GF laminates, and the composite with 0/90 orientation of WRGF has higher tensile strength and modulus compared to that with ±45 orientation of WRGF. Both composite with 0/90 and ±45 orientation of WRGF have similar burning resistance (TTI and BR) and the composite containing 13 laminates of WR-GF shows the best burning resistance. According to these properties, this composite has good opportunity to be applied as car body panels or other structure in industries due to save weight and high burning resistance.

  9. Optical constants using two particle size distributions: On-going laboratory efforts to quantitatively address clay abundance on Mars

    NASA Astrophysics Data System (ADS)

    Roush, T. L.; Bishop, J. L.; Brown, A. J.; Blake, D.; Bristow, T.

    2013-12-01

    Data obtained at visible and near-infrared wavelengths by OMEGA on MarsExpress and CRISM on MRO provide definitive evidence for the presence of phyllosilicates and other hydrated phases on Mars. A diverse range of both Fe/Mg-OH and Al-OH-bearing phyllosilicates were identified including the smectites, nontronite, saponite, and montmorillonite. In order to constrain the abundances of these phyllosilicates spectral analyses of mixtures of pure end-members are needed. We report on the final stages of our on-going effort to enable the quantitative evaluation of the abundance of hydrated-hydroxylated silicates when they are contained in mixtures. We include several two component mixtures of hydrated/hydroxylated silicates with each other and with two analogs for other martian materials: pyroxene (enstatite) and palagonitic soil (an alteration product of basaltic glass). For the hydrated-hydroxylated silicates we include saponite and montmorillonite (Mg- and Al- rich smectites). We prepared three size separates of each end-member for study: 20-45, 63-90, and 125-150 μm. We used scanning electron microscope images to characterize the grain size distribution, of each sample. Using the grain size distribution, we have derived initial estimates of the optical constants of these materials and compare them to values estimated for the same samples, but using the mean particle size of the sieve fraction. We discuss the results of our calculations for these materials and their implications for modeling the physical mixtures and eventual comparison to Martian spectra.

  10. Water sites at a clay interface

    SciTech Connect

    Grandjean, J.

    1997-01-15

    Aqueous suspensions of swelling clays (smectites) find uses in many industrial applications including drilling fluids, suspending agents and water treatment. {sup 2}H NMR quadrupolar splittings of clay suspensions monitor the orientation of water molecules near the solid surface. Two limiting water interfacial sites explain the results on montmorillonite, hectorite, and saponite suspensions. The location of cation isomorphous substitution and the Ca{sup 2+}/Na{sup +} molar ratio of exchangeable cations modulate their relative importance. With beidellite suspensions, water orientation at the clay surface cannot be described within the above scheme.

  11. Large-scale coherent orientations of quasar polarisation vectors: interpretation in terms of axion-like particles

    SciTech Connect

    Payez, A.; Hutsemekers, D.; Cudell, J. R.

    2010-08-30

    The observation of redshift-dependent coherent orientations of quasar polarisation vectors over cosmological distances in some regions of the sky is reviewed. Based on a good-quality sample of 355 measured quasars, this observation seems to infer the existence of a new effect acting on light propagation on such huge distances.A solution in terms of nearly massless axion-like particles has been proposed in the literature and its current status is discussed.

  12. Contact micromechanics in granular media with clay

    SciTech Connect

    Ita, S.L.

    1994-08-01

    Many granular materials, including sedimentary rocks and soils, contain clay particles in the pores, grain contacts, or matrix. The amount and location of the clays and fluids can influence the mechanical and hydraulic properties of the granular material. This research investigated the mechanical effects of clay at grain-to-grain contacts in the presence of different fluids. Laboratory seismic wave propagation tests were conducted at ultrasonic frequencies using spherical glass beads coated with Montmorillonite clay (SWy-1) onto which different fluids were adsorbed. For all bead samples, seismic velocity increased and attenuation decreased as the contact stiffnesses increased with increasing stress demonstrating that grain contacts control seismic transmission in poorly consolidated and unconsolidated granular material. Coating the beads with clay added stiffness and introduced viscosity to the mechanical contact properties that increased the velocity and attenuation of the propagating seismic wave. Clay-fluid interactions were studied by allowing the clay coating to absorb water, ethyl alcohol, and hexadecane. Increasing water amounts initially increased seismic attenuation due to clay swelling at the contacts. Attenuation decreased for higher water amounts where the clay exceeded the plastic limit and was forced from the contact areas into the surrounding open pore space during sample consolidation. This work investigates how clay located at grain contacts affects the micromechanical, particularly seismic, behavior of granular materials. The need for this work is shown by a review of the effects of clays on seismic wave propagation, laboratory measurements of attenuation in granular media, and proposed mechanisms for attenuation in granular media.

  13. How clays weaken faults.

    NASA Astrophysics Data System (ADS)

    van der Pluijm, Ben A.; Schleicher, Anja M.; Warr, Laurence N.

    2010-05-01

    The weakness of upper crustal faults has been variably attributed to (i) low values of normal stress, (ii) elevated pore-fluid pressure, and (iii) low frictional strength. Direct observations on natural faults rocks provide new evidence for the role of frictional properties on fault strength, as illustrated by our recent work on samples from the San Andreas Fault Observatory at Depth (SAFOD) drillhole at Parkfield, California. Mudrock samples from fault zones at ~3066 m and ~3296 m measured depth show variably spaced and interconnected networks of displacement surfaces that consist of host rock particles that are abundantly coated by polished films with occasional striations. Transmission electron microscopy and X-ray diffraction study of the surfaces reveal the occurrence of neocrystallized thin-film clay coatings containing illite-smectite (I-S) and chlorite-smectite (C-S) phases. X-ray texture goniometry shows that the crystallographic fabric of these faults rocks is characteristically low, in spite of an abundance of clay phases. 40Ar/39Ar dating of the illitic mix-layered coatings demonstrate recent crystallization and reveal the initiation of an "older" fault strand (~8 Ma) at 3066 m measured depth, and a "younger" fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, reflecting continued activation of these clay-weakened zones. We propose that the majority of slow fault creep is controlled by the high density of thin (< 100nm thick) nano-coatings on fracture surfaces, which become sufficiently smectite-rich and interconnected at low angles to allow slip with minimal breakage of stronger matrix clasts. Displacements are accommodated by localized frictional slip along coated particle surfaces and hydrated smectitic phases, in combination with intracrystalline deformation of the clay lattice, associated with extensive mineral dissolution, mass transfer and continued growth of expandable layers. The

  14. Killer clays! Natural antibacterial clay minerals

    USGS Publications Warehouse

    Williams, L.B.; Holland, M.; Eberl, D.D.; Brunet, T.; De Courrsou, L. B.

    2004-01-01

    The clay chemical properties that may be important in medicine were investigated. It was found that natural clay minerals can have striking and very specific effects on microbial populations. The effects can range from potentially enhanced microbial growth to complete sterilization. This paper presents evidence that natural clay minerals can be effective antimicrobial agents.

  15. 3D Joint Speaker Position and Orientation Tracking with Particle Filters

    PubMed Central

    Segura, Carlos; Hernando, Javier

    2014-01-01

    This paper addresses the problem of three-dimensional speaker orientation estimation in a smart-room environment equipped with microphone arrays. A Bayesian approach is proposed to jointly track the location and orientation of an active speaker. The main motivation is that the knowledge of the speaker orientation may yield an increased localization performance and vice versa. Assuming that the sound produced by the speaker is originated from his mouth, the center of the head is deduced based on the estimated head orientation. Moreover, the elevation angle of the head of the speaker can be partly inferred from the fast vertical movements of the computed mouth location. In order to test the performance of the proposed algorithm, a new multimodal dataset has been recorded for this purpose, where the corresponding 3D orientation angles are acquired by an inertial measurement unit (IMU) provided by accelerometers, magnetometers and gyroscopes in the three-axes. The proposed joint algorithm outperforms a two-step approach in terms of localization and orientation angle precision assessing the superiority of the joint approach. PMID:24481230

  16. 3D joint speaker position and orientation tracking with particle filters.

    PubMed

    Segura, Carlos; Hernando, Javier

    2014-01-01

    This paper addresses the problem of three-dimensional speaker orientation estimation in a smart-room environment equipped with microphone arrays. A Bayesian approach is proposed to jointly track the location and orientation of an active speaker. The main motivation is that the knowledge of the speaker orientation may yield an increased localization performance and vice versa. Assuming that the sound produced by the speaker is originated from his mouth, the center of the head is deduced based on the estimated head orientation. Moreover, the elevation angle of the head of the speaker can be partly inferred from the fast vertical movements of the computed mouth location. In order to test the performance of the proposed algorithm, a new multimodal dataset has been recorded for this purpose, where the corresponding 3D orientation angles are acquired by an inertial measurement unit (IMU) provided by accelerometers, magnetometers and gyroscopes in the three-axes. The proposed joint algorithm outperforms a two-step approach in terms of localization and orientation angle precision assessing the superiority of the joint approach. PMID:24481230

  17. Vector Radiative Transfer Equation for Arbitrarily Shaped and Arbitrarily Oriented Particles: A Microphysical Derivation from Statistical Electromagnetics

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.

    2003-01-01

    We use the concepts of statistical electromagnetics to derive the general radiative transfer equation (RTE) describing multiple scattering of polarized light by sparse discrete random media consisting of arbitrarily shaped and arbitrarily oriented particles. The derivation starts from the volume integral and Lippmann-Schwinger equations for the electric field scattered by a fixed N-particle system and proceeds to the vector form of the Foldy-Lax equations and their approximate far-field version. We then assume that particle positions are completely random and derive the vector RTE by applying the Twersky approximation to the coherent electric field and the Twersky and ladder approximations to the coherency dyad of the diffuse field in the limit N -> infinity. The concluding section discusses the physical meaning of the quantities entering the general vector RTE and the assumptions made in its derivation.

  18. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES

    EPA Science Inventory

    CLAY AND CLAY-SUPPORTED REAGENTS HAVE BEEN USED EXTENSIVELY FOR SYNTHETIC ORGANIC TRANSFORMATIONS. THIS OVERVIEW DESCRIBES THE SALIENT STRUCTURAL PROPERTIES OF VARIOUS CLAY MATERIALS AND EXTENDS THE DISCUSSION TO PILLARED CLAYS AND REAGENTS SUPPORTED ON CLAY MATERIALS. A VARIET...

  19. Structure and orientation of small particles of platinum deposited on NaCl and mica

    NASA Technical Reports Server (NTRS)

    Renou, A.; Gillet, M.

    1979-01-01

    The structure of small platinum particles condensed in vacuum onto NaCl (001), NaCl (111) and mica substrates was studied by electron diffraction and electron microscopy. Results show that above a certain substrate temperature decahedral or icosahedral particles are formed. These particles are practically absent with substrates cleaved in high vacuum. They are always much less numerous than in gold films prepared under the same conditions. Assumptions made to explain this phenomenon are: (1) the initial growth of an abnormal structure of the nuclei as opposed by the substrate; (2) the particles disappear before they attain a size which corresponds to the observations; and (3) the particles result from a coalescence mechanism leading to multiple twinned particles.

  20. Orientational dynamics of ferrofluids with finite magnetic anisotropy of the particles: relaxation of magneto-birefringence in crossed fields.

    PubMed

    Raikher, Yu L; Stepanov, V I; Bacri, J-C; Perzynski, R

    2002-08-01

    Dynamic birefringence in a ferrofluid subjected to crossed bias (constant) and probing (pulse or ac) fields is considered, assuming that the nanoparticles have finite magnetic anisotropy. This is done on the basis of the general Fokker-Planck equation that takes into account both internal magnetic and external mechanical degrees of freedom of the particle. We describe the orientation dynamics in terms of the integral relaxation time of the macroscopic orientation order parameter. To account for an arbitrary relation between the bias (external) and anisotropy (internal) fields, an interpolation expression for the integral relaxation time is proposed and justified. A developed description is used to interpret the measurements of birefringence relaxation in magnetic fluids with nanoparticles of high (cobalt ferrite) and low (maghemite) anisotropy. The proposed theory appears to be in full qualitative agreement with all the experimental data available. PMID:12241160

  1. Hybrid Effect on Whisker Orientation Dependence of Composite Strength of Aluminum Cast Alloy Reinforced by Al2O3 Whiskers and SiC Particles

    NASA Astrophysics Data System (ADS)

    Md, Rafiquzzaman; Arai, Yoshio

    The hybrid effect on the orientation dependence of the composite strength of an aluminum cast alloy reinforced by Al2O3 whiskers and SiC particles is studied experimentally and numerically. Two types of specimens are prepared for monotonic bending tests. The longitudinal specimen orientation (maximum stress direction) is parallel to or normal to randomly oriented whiskers in plane. The monotonic strength is 18% higher when the hybrid metal matrix composite (MMC) is subjected to an external load parallel to the random whisker orientation in plane than when the load is perpendicular to the whisker orientation. The whisker orientation dependence of composite strength in hybrid composite is weaker than that in whisker-reinforced composite. On the fracture surface of the specimen loaded along the direction parallel to the random whisker orientation in plane, most whiskers are broken while many de-bonded interfaces between the whiskers and matrix are observed on the fracture surface of the specimen loaded along the direction perpendicular to the whisker orientation. To characterize the hybrid effect on the whisker orientation dependence of composite strength, a three-dimensional hybrid composite unit cell model including one whisker and a few particles under a periodic boundary condition is developed using the finite element method. The hybrid composites have higher whisker stress than whisker-reinforced composite when subjected to an external load parallel to the whisker orientation if these composites have the same total volume fraction of reinforcement and the particles are distributed randomly. Under an external load perpendicular to the whisker orientation, the interface stress of hybrid composites is lower than that of whisker-reinforced composite. As a result, the strength difference for parallel and perpendicular loading conditions of the hybrid composites is smaller than that of whisker-reinforced composite. Thus, the weak whisker orientation effect in the

  2. Imprinted Clay Coil Vessels

    ERIC Educational Resources Information Center

    Lohr, Tresa Rae

    2006-01-01

    The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

  3. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global common clay and shale industry, particularly in the U.S. It claims that common clay and shale is mainly used in the manufacture of heavy clay products like brick, flue tile and sewer pipe. The main producing states in the U.S. include North Carolina, New York and Oklahoma. Among the firms that manufacture clay and shale-based products are Mid America Brick & Structural Clay Products LLC and Boral USA.

  4. Formation of oriented particles in an amorphous host: ZnS nanocrystals in silicon

    SciTech Connect

    Meldrum, A.; Zuhr, R.A.; Sonder, E.; Budai, J.D.; White, C.W.; Boatner, L.A.; Ewing, R.C.; Henderson, D.O.

    1999-02-01

    Processes for incorporating randomly oriented crystalline precipitates in an amorphous host can be traced back to the 17th century when Cassius produced {open_quotes}gold ruby{close_quotes} glass. In this glass, octahedral colloidal precipitates of gold scatter light by the Mie process to produce a deep red color. In contrast to gold ruby glass, we describe a type of material in which the crystalline precipitates are crystallographically aligned in a coherent manner{emdash}even though they are dispersed in an amorphous matrix. Ion implantation and thermal processing are first used to form zinc sulfide nanocrystals that are coherently oriented with respect to a crystalline Si host. The Si is then amorphized by ion irradiation leaving the highly radiation-resistant ZnS precipitates in an aligned crystalline state. The process is anticipated to find applications in the creation of surfaces with unique optoelectronic properties. {copyright} {ital 1999 American Institute of Physics.}

  5. Iodide uptake by negatively charged clay interlayers?

    PubMed

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-09-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. PMID:26057987

  6. Membrane behavior of clay liner materials

    NASA Astrophysics Data System (ADS)

    Kang, Jong Beom

    Membrane behavior represents the ability of porous media to restrict the migration of solutes, leading to the existence of chemico-osmosis, or the flow of liquid in response to a chemical concentration gradient. Membrane behavior is an important consideration with respect to clay soils with small pores and interactive electric diffuse double layers associated with individual particles, such as bentonite. The results of recent studies indicate the existence of membrane behavior in bentonite-based hydraulic barriers used in waste containment applications. Thus, measurement of the existence and magnitude of membrane behavior in such clay soils is becoming increasingly important. Accordingly, this research focused on evaluating the existence and magnitude of membrane behavior for three clay-based materials that typically are considered for use as liners for waste containment applications, such as landfills. The three clay-based liner materials included a commercially available geosynthetic clay liner (GCL) consisting of sodium bentonite sandwiched between two geotextiles, a compacted natural clay known locally as Nelson Farm Clay, and compacted NFC amended with 5% (dry wt.) of a sodium bentonite. The study also included the development and evaluation of a new flexible-wall cell for clay membrane testing that was used subsequently to measure the membrane behaviors of the three clay liner materials. The consolidation behavior of the GCL under isotropic states of stress also was evaluated as a preliminary step in the determination of the membrane behavior of the GCL under different effective consolidation stresses.

  7. Multishell Au/Ag/SiO2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

    DOE PAGESBeta

    Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier; Fang, Ning

    2015-04-07

    In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of the hybridmore » nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.« less

  8. Ostwald ripening of clays and metamorphic minerals

    USGS Publications Warehouse

    Eberl, D.D.; Srodon, J.; Kralik, M.; Taylor, B.E.; Peterman, Z.E.

    1990-01-01

    Analyses of particle size distributions indicate that clay minerals and other diagenetic and metamorphic minerals commonly undergo recrystallization by Ostwald ripening. The shapes of their particle size distributions can yield the rate law for this process. One consequence of Ostwald ripening is that a record of the recrystallization process is preserved in the various particle sizes. Therefore, one can determine the detailed geologic history of clays and other recrystallized minerals by separating, from a single sample, the various particle sizes for independent chemical, structural, and isotopic analyses.

  9. Magnetic properties in oriented platelet Fe3O4 particles prepared by the polyol method using α-FeOOH as precursors

    NASA Astrophysics Data System (ADS)

    Kishimoto, Mikio; Isaka, Daiki; Horiuchi, Akari; Yanagihara, Hideto; Kita, Eiji

    2014-02-01

    Magnetic properties of platelet Fe3O4 particles were studied to apply them to magnetic hyperthermia or thermoablation using hysteresis-loss heating. As precursor materials, platelet α-FeOOH particles were synthesized by a hydrothermal treatment of the precipitated Fe3+ ions in an alkaline solution of ethanolamine. Spinel-structured iron oxide particles were obtained from the platelet α-FeOOH particles by a liquid-phase reduction process using tetra-ethylene glycol as the reducing agent and were recognized as platelet particles with size 30-100 nm by transmission electron microscopy. Their chemical composition and crystal structure were confirmed to be that of Fe3O4 by X-ray diffraction and Mössbauer analyses. The coercive force and saturation magnetization of the Fe3O4 particles were 11.9 kA/m and 77.9 Am2/kg, respectively. A tape was prepared by orientating the platelet Fe3O4 particles in such a way that the particle planes were parallel to the tape plane. The calculated magnetic anisotropy field of the Fe3O4 particles was about two times larger than the in-plane coercive force of 12.6 kA/m of the oriented tape. The saturation field in direction perpendicular to the oriented tape was 390 kA/m, which is close to the demagnetizing field in the platelet Fe3O4 particles.

  10. Effect of aging on rheology of ball clay suspensions

    NASA Astrophysics Data System (ADS)

    Tonthai, Tienchai

    2002-01-01

    The behaviors of clay-water suspensions such as deflocculation or rheological properties are not constant but change with time. Aging has been recognized for changing the rheological properties of clay suspensions. This work provided information about the effects of the moisture contents in ball clay lumps and clay air exposure time on their processability. Dynamic oscillatory rheometry using a vane-in-cup geometry was used to characterize the rheological behavior of ball clay suspensions in terms of elastic modulus, viscous modulus and yield stress as a function of aging time. A light scattering size analyzer was used to examine the agglomerate size distribution of ball clay suspensions which affected the rheological behavior. Soluble ion release (both cations and anions) in the filtrate of suspensions was measured by ion chromatography. Low and high lignitic ball clay suspensions were dispersed with sodium silicate (Na2SiO3) or sodium polyacrylate at specific gravity 1.3 and 1.6 in two dispersion states: fully deflocculated (minimum viscosity) and under deflocculated. Suspensions prepared using freshly mined ball clays required more dispersant than suspensions prepared using dry ball clays to achieve minimum viscosity due to a difference in agglomerate size distribution. The agglomerate size distribution of suspensions prepared using dry clays was broader than that of suspensions prepared using freshly mined clays. In suspensions prepared using freshly mined clays, there were many uniformly small agglomerates having loose water inside, while in suspensions prepared using dry clays, the capillary effect and bonding between clay particles resulting from drying broke clay aggregates apart into agglomerate structures composed of a few to many clay particles. For suspensions prepared using dry clays after one day suspension aging, the elastic modulus and yield stress decreased due to the change in agglomerate size distribution of suspensions but increased for

  11. Clays and other minerals in prebiotic processes

    NASA Technical Reports Server (NTRS)

    Paecht-Horowitz, M.

    1984-01-01

    Clays and other minerals have been investigated in context with prebiotic processes, mainly in polymerization of amino acids. It was found that peptides adsorbed on the clay, prior to polymerization, influence the reaction. The ratio between the amount of the peptides adsorbed and that of the clay is important for the yield as well as for the degrees of polymerization obtained. Adsorption prior to reaction produces a certain order in the aggregates of the clay particles which might induce better reaction results. Excess of added peptides disturbs this order and causes lesser degrees of polymerization. In addition to adsorption, clays are also able to occlude between their layers substances out of the environment, up to very high concentrations.

  12. Rheo-SAXS investigation of shear-thinning behaviour of very anisometric repulsive disc-like clay suspensions.

    PubMed

    Philippe, A M; Baravian, C; Imperor-Clerc, M; De Silva, J; Paineau, E; Bihannic, I; Davidson, P; Meneau, F; Levitz, P; Michot, L J

    2011-05-18

    Aqueous suspensions of swelling clay minerals exhibit a rich and complex rheological behaviour. In particular, these repulsive systems display strong shear-thinning at very low volume fractions in both the isotropic and gel states. In this paper, we investigate the evolution with shear of the orientational distribution of aqueous clay suspensions by synchrotron-based rheo-SAXS experiments using a Couette device. Measurements in radial and tangential configurations were carried out for two swelling clay minerals of similar morphology and size, Wyoming montmorillonite and Idaho beidellite. The shear evolution of the small angle x-ray scattering (SAXS) patterns displays significantly different features for these two minerals. The detailed analysis of the angular dependence of the SAXS patterns in both directions provides the average Euler angles of the statistical effective particle in the shear plane. We show that for both samples, the average orientation is fully controlled by the local shear stress around the particle. We then apply an effective approach to take into account multiple hydrodynamic interactions in the system. Using such an approach, it is possible to calculate the evolution of viscosity as a function of shear rate from the knowledge of the average orientation of the particles. The viscosity thus recalculated almost perfectly matches the measured values as long as collective effects are not too important in the system. PMID:21525562

  13. Communicating with Clay.

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2000-01-01

    Presents a unit on clay that is centered around sign language in which students explore the slab method of working with clay. States that each student picks a letter of the sign language alphabet and fashions a clay hand to depict the letter. (CMK)

  14. Source apportionment of fine particles in Tennessee using a source-oriented model.

    PubMed

    Doraiswamy, Prakash; Davis, Wayne T; Miller, Terry L; Fu, Joshua S

    2007-04-01

    Source apportionment of fine particles (PM2.5, particulate matter < 2 microm in aerodynamic diameter) is important to identify the source categories that are responsible for the concentrations observed at a particular receptor. Although receptor models have been used to do source apportionment, they do not fully take into account the chemical reactions (including photochemical reactions) involved in the formation of secondary fine particles. Secondary fine particles are formed from photochemical and other reactions involving precursor gases, such as sulfur dioxide, oxides of nitrogen, ammonia, and volatile organic compounds. This paper presents the results of modeling work aimed at developing a source apportionment of primary and secondary PM2.5. On-road mobile source and point source inventories for the state of Tennessee were estimated and compiled. The national emissions inventory for the year 1999 was used for the other states. U.S. Environmental Protection Agency Models3/Community Multi-Scale Air Quality modeling system was used for the photochemical/secondary particulate matter modeling. The modeling domain consisted of a nested 36-12-4-km domain. The 4-km domain covered the entire state of Tennessee. The episode chosen for the modeling runs was August 29 to September 9, 1999. This paper presents the approach used and the results from the modeling and attempts to quantify the contribution of major source categories, such as the on-road mobile sources (including the fugitive dust component) and coal-fired power plants, to observed PM2.5 concentrations in Tennessee. The results of this work will be helpful in policy issues targeted at designing control strategies to meet the PM2.5 National Ambient Air Quality Standards in Tennessee. PMID:17458460

  15. Magnetic characterization of noninteracting, randomly oriented, nanometer-scale ferrimagnetic particles

    NASA Astrophysics Data System (ADS)

    Cao, Changqian; Tian, Lanxiang; Liu, Qingsong; Liu, Weifeng; Chen, Guanjun; Pan, Yongxin

    2010-07-01

    Studying the magnetic properties of ultrafine nanometer-scale ferrimagnetic particles (<10 nm) is vital to our understanding of superparamagnetism and its applications to environmental magnetism, biogeomagnetism, iron biomineralization, and biomedical technology. However, magnetic properties of the ultrafine nanometer-sized ferrimagnetic grains are very poorly constrained because of ambiguities caused by particle magnetostatic interactions and unknown size distributions. To resolve these problems, we synthesized magnetoferritins using the recombinant human H chain ferritin (HFn). These ferrimagnetic HFn were further purified through size exclusion chromatography to obtain monodispersed ferrimagnetic HFn. Transmission electron microscopy revealed that the purified ferrimagnetic HFn are monodispersed and each consists of an iron oxide core (magnetite or maghemite) with an average core diameter of 3.9 ± 1.1 nm imbedded in an intact protein shell. The R value of the Wohlfarth-Cisowski test measured at 5 K is 0.5, indicating no magnetostatic interactions. The saturation isothermal remanent magnetization acquired at 5 K decreased rapidly with increasing temperature with a median unblocking temperature of 8.2 K. The preexponential frequency factor f0 determined by AC susceptibility is (9.2 ± 7.9) × 1010 Hz. The extrapolated Mrs/Ms and Bcr/Bc at 0 K are 0.5 and 1.12, respectively, suggesting that the ferrimagnetic HFn cores are dominated by uniaxial anisotropy. The calculated effective magnetic anisotropy energy constant Keff = 1.2 × 105 J/m3, which is larger than previously reported values for bulk magnetite and/or maghemite or magnetoferritin and is attributed to the effect of surface anisotropy. These data provide useful insights into superparamagnetism as well as biomineralization of ultrafine ferrimagnetic particles.

  16. Direct simulations of orientational dispersion of platelet particles in a viscoelastic fluid subjected to a partial drag flow for effective coloring of polymers

    NASA Astrophysics Data System (ADS)

    Hwang, Wook Ryol; Kim, Worl-Yong; Lee, Eon-Seok; Park, Chung-Hae

    2011-09-01

    In this study, we performed three dimensional viscoelastic flow simulations with freely suspended platelet particles for the application of effective coloring of polymers. The model problem with a partial drag surface mimics a recently proposed design to remove typical platelet particle orientation near the weld line. A standard combination for the particulate viscoelastic flow simulation techniques is employed: (i) the discrete viscous elastic stress splitting (DEVSS) scheme for the stable solution of the viscoelastic flow; (ii) the discontinuous Galerkin (DG) method to deal with the convection term in the viscoelastic stress evolution equation; (iii) a fictitious domain method (the rigid-shell description) for implicit treatment of the hydrodynamic interaction between particles and fluid. Through example problems with a single, two and many platelet particles, we report that the angular rotation of platelet particles is significantly reduced in a viscoelastic (Giesekus) fluid compared with that in a Newtonian fluid and that non-uniform angular rotation of particles can be generated by the spatial distribution of particles, which facilitates enhanced orientational dispersion by randomizing the platelet particle orientation.

  17. Orientational Coherent Effects of High-Energy Particles in a LiNbO3 Crystal

    NASA Astrophysics Data System (ADS)

    Bagli, E.; Guidi, V.; Mazzolari, A.; Bandiera, L.; Germogli, G.; Sytov, A. I.; De Salvador, D.; Argiolas, A.; Bazzan, M.; Carnera, A.; Berra, A.; Bolognini, D.; Lietti, D.; Prest, M.; Vallazza, E.

    2015-07-01

    A bent lithium niobate strip was exposed to a 400 -GeV /c proton beam at the external lines of CERN Super Proton Synchrotron to probe its capabilities versus coherent interactions of the particles with the crystal such as channeling and volume reflection. Lithium niobate (LiNbO3 ) exhibits an interplanar electric field comparable to that of Silicon (Si) and remarkable piezoelectric properties, which could be exploited for the realization of piezo-actuated devices for the control of high-energy particle beams. In contrast to Si and germanium (Ge), LiNbO3 shows an intriguing effect; in spite of a low channeling efficiency (3%), the volume reflection maintains a high deflection efficiency (83%). Such discrepancy was ascribed to the high concentration (1 04 per cm2 ) of dislocations in our sample, which was obtained from a commercial wafer. Indeed, it has been theoretically shown that a channeling efficiency comparable with that of Si or Ge would be attained with a crystal at low defect concentration (less than ten per cm2 ). To better understand the role of dislocations on volume reflection, we have worked out computer simulation via dynecharm++ Monte Carlo code to study the effect of dislocations on volume reflection. The results of the simulations agree with experimental records, demonstrating that volume reflection is more robust than channeling in the presence of dislocations.

  18. Orientational Coherent Effects of High-Energy Particles in a LiNbO3 Crystal.

    PubMed

    Bagli, E; Guidi, V; Mazzolari, A; Bandiera, L; Germogli, G; Sytov, A I; De Salvador, D; Argiolas, A; Bazzan, M; Carnera, A; Berra, A; Bolognini, D; Lietti, D; Prest, M; Vallazza, E

    2015-07-01

    A bent lithium niobate strip was exposed to a 400-GeV/c proton beam at the external lines of CERN Super Proton Synchrotron to probe its capabilities versus coherent interactions of the particles with the crystal such as channeling and volume reflection. Lithium niobate (LiNbO3) exhibits an interplanar electric field comparable to that of Silicon (Si) and remarkable piezoelectric properties, which could be exploited for the realization of piezo-actuated devices for the control of high-energy particle beams. In contrast to Si and germanium (Ge), LiNbO3 shows an intriguing effect; in spite of a low channeling efficiency (3%), the volume reflection maintains a high deflection efficiency (83%). Such discrepancy was ascribed to the high concentration (10(4) per cm2) of dislocations in our sample, which was obtained from a commercial wafer. Indeed, it has been theoretically shown that a channeling efficiency comparable with that of Si or Ge would be attained with a crystal at low defect concentration (less than ten per cm2). To better understand the role of dislocations on volume reflection, we have worked out computer simulation via dynecharm++ Monte Carlo code to study the effect of dislocations on volume reflection. The results of the simulations agree with experimental records, demonstrating that volume reflection is more robust than channeling in the presence of dislocations. PMID:26182106

  19. Clays in prebiological chemistry

    NASA Technical Reports Server (NTRS)

    Rao, M.; Oro, J.; Odom, D. G.

    1980-01-01

    The ways in which clays have been utilized in studies of prebiological chemistry are reviewed, and an assessment is given of the possible role of clays in prebiological systems. The adsorption of organic molecules on clays has been demonstrated, as has the synthesis of bioorganic monomers in the presence of clays. For instance, amino acids, purines and pyrimidines have been obtained from carbon monoxide and nitric acid in the presence of clays at relatively high temperatures (250-325 C). The oligomerization of biochemical monomers, mediated by clays, has also been shown to result in the formation of polymer molecules basic to life. Clays have also been found to affect the condensation of mononucleotides to oligonucleotides.

  20. A Chaotic Particle Swarm Optimization-Based Heuristic for Market-Oriented Task-Level Scheduling in Cloud Workflow Systems

    PubMed Central

    Li, Xuejun; Xu, Jia; Yang, Yun

    2015-01-01

    Cloud workflow system is a kind of platform service based on cloud computing. It facilitates the automation of workflow applications. Between cloud workflow system and its counterparts, market-oriented business model is one of the most prominent factors. The optimization of task-level scheduling in cloud workflow system is a hot topic. As the scheduling is a NP problem, Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO) have been proposed to optimize the cost. However, they have the characteristic of premature convergence in optimization process and therefore cannot effectively reduce the cost. To solve these problems, Chaotic Particle Swarm Optimization (CPSO) algorithm with chaotic sequence and adaptive inertia weight factor is applied to present the task-level scheduling. Chaotic sequence with high randomness improves the diversity of solutions, and its regularity assures a good global convergence. Adaptive inertia weight factor depends on the estimate value of cost. It makes the scheduling avoid premature convergence by properly balancing between global and local exploration. The experimental simulation shows that the cost obtained by our scheduling is always lower than the other two representative counterparts. PMID:26357510

  1. A Chaotic Particle Swarm Optimization-Based Heuristic for Market-Oriented Task-Level Scheduling in Cloud Workflow Systems.

    PubMed

    Li, Xuejun; Xu, Jia; Yang, Yun

    2015-01-01

    Cloud workflow system is a kind of platform service based on cloud computing. It facilitates the automation of workflow applications. Between cloud workflow system and its counterparts, market-oriented business model is one of the most prominent factors. The optimization of task-level scheduling in cloud workflow system is a hot topic. As the scheduling is a NP problem, Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO) have been proposed to optimize the cost. However, they have the characteristic of premature convergence in optimization process and therefore cannot effectively reduce the cost. To solve these problems, Chaotic Particle Swarm Optimization (CPSO) algorithm with chaotic sequence and adaptive inertia weight factor is applied to present the task-level scheduling. Chaotic sequence with high randomness improves the diversity of solutions, and its regularity assures a good global convergence. Adaptive inertia weight factor depends on the estimate value of cost. It makes the scheduling avoid premature convergence by properly balancing between global and local exploration. The experimental simulation shows that the cost obtained by our scheduling is always lower than the other two representative counterparts. PMID:26357510

  2. A fast object-oriented Matlab implementation of the Reproducing Kernel Particle Method

    NASA Astrophysics Data System (ADS)

    Barbieri, Ettore; Meo, Michele

    2012-05-01

    Novel numerical methods, known as Meshless Methods or Meshfree Methods and, in a wider perspective, Partition of Unity Methods, promise to overcome most of disadvantages of the traditional finite element techniques. The absence of a mesh makes meshfree methods very attractive for those problems involving large deformations, moving boundaries and crack propagation. However, meshfree methods still have significant limitations that prevent their acceptance among researchers and engineers, namely the computational costs. This paper presents an in-depth analysis of computational techniques to speed-up the computation of the shape functions in the Reproducing Kernel Particle Method and Moving Least Squares, with particular focus on their bottlenecks, like the neighbour search, the inversion of the moment matrix and the assembly of the stiffness matrix. The paper presents numerous computational solutions aimed at a considerable reduction of the computational times: the use of kd-trees for the neighbour search, sparse indexing of the nodes-points connectivity and, most importantly, the explicit and vectorized inversion of the moment matrix without using loops and numerical routines.

  3. Synthetic clay-magnetite aggregates designed for controlled deposition experiments

    NASA Astrophysics Data System (ADS)

    Feinberg, J. M.; Galindo-Gonzalez, C.; Kasama, T.; Cervera, L.; Posfai, M.; Harrison, R. J.; Dunin-Borkowski, R. E.

    2007-12-01

    The behavior of magnetic particles in fluid environments is key to the acquisition of detrital remanence magnetization and is essential to a multitude of industrial applications. This study introduces a series of synthetic clay-magnetite aggregates whose physical attributes can be tailored for controlled depositional experiments. We describe the mineralogical structure and magnetic behavior of montmorillonite platelets coated with nanometer-scale magnetite crystals using both electron microscopy and rock magnetism techniques. Selected area electron diffraction of the magnetite and the montmorillonite host shows no evidence of preferred orientation or oriented aggregation. Grain size distributions of magnetite in three different clay-magnetite assemblages were directly measured using conventional bright-field transmission electron microscopy. The spacing of the magnetite grains and their three-dimensional distribution around individual clay platelets was imaged using a tomographic reconstruction generated from high-angle annular dark-field (HAADF) images. The grain size distributions determined from the bright-field images and the tomographic reconstruction agree within error with estimates derived from magnetic granulometry techniques based on magnetic hysteresis and low-field susceptibility measurements. All three samples behave superparamagnetically at room temperature, and display increasing levels of single domain behavior as the samples are cooled to liquid nitrogen temperatures (- 195°C). Off-axis electron holography images show that superparamagnetic grains are also stabilized into flux closure structures at -195°C. The average spacing between adjacent magnetite crystals and the overall platelet shape of the aggregates creates an anisotropy of magnetic susceptibility that allows assemblages to align with external magnetic fields at room temperature. By adjusting the dimensions and concentrations of the magnetite grains in these aggregates, we can create

  4. Silt-clay aggregates on Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1979-01-01

    Viking observations suggest abundant silt and clay particles on Mars. It is proposed that some of these particles agglomerate to form sand size aggregates that are redeposited as sandlike features such as drifts and dunes. Although the binding for the aggregates could include salt cementation or other mechanisms, electrostatic bonding is considered to be a primary force holding the aggregates together. Various laboratory experiments conducted since the 19th century, and as reported here for simulated Martian conditions, show that both the magnitude and sign of electrical charges on windblown particles are functions of particle velocity, shape and composition, atmospheric pressure, atmospheric composition and other factors. Electrical charges have been measured for saltating particles in the wind tunnel and in the field, on the surfaces of sand dunes, and within dust clouds on earth. Similar, and perhaps even greater, charges are proposed to occur on Mars, which could form aggregates of silt and clay size particles

  5. Preferred orientation and elastic anisotropy in shales.

    SciTech Connect

    Lonardelli, I.; Wenk, H.-R.; Ren, Y.; Univ. of California at Berkeley

    2007-03-01

    Anisotropy in shales is becoming an important issue in exploration and reservoir geophysics. In this study, the crystallographic preferred orientation of clay platelets that contributes to elastic anisotropy was determined quantitatively by hard monochromatic X-ray synchrotron diffraction in two different shales from drillholes off the coast of Nigeria. To analyze complicated diffraction images with five different phases (illite/smectite, kaolinite, quartz, siderite, feldspar) and many overlapping peaks, we applied a methodology based on the crystallographic Rietveld method. The goal was to describe the intrinsic physical properties of the sample (phase composition, crystallographic preferred orientation, crystal structure, and microstructure) and compute macroscopic elastic properties by averaging single crystal properties over the orientation distribution for each phase. Our results show that elastic anisotropy resulting from crystallographic preferred orientation of the clay particles can be determined quantitatively. This provides a possible way to compare measured seismic anisotropy and texture-derived anisotropy and to estimate the contribution of the low-aspect ratio pores aligned with bedding.

  6. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  7. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

  8. Silver as Seed-Particle Material for GaAs Nanowires—Dictating Crystal Phase and Growth Direction by Substrate Orientation

    PubMed Central

    2016-01-01

    Here we investigate the feasibility of silver as seed-particle material to synthesize GaAs nanowires and show that both crystal phase and growth direction can be controlled by choice of substrate orientation. A (111)B substrate orientation can be used to form vertically aligned wurtzite GaAs nanowires and a (100) substrate orientation to form vertically aligned zinc blende GaAs nanowires. A 45–50% yield of vertical nanowire growth is achieved on the (100) substrate orientation without employing any type of surface modification or nucleation strategy to promote a vertical growth direction. In addition, photoluminescence measurements reveal that the photon emission from the silver seeded wurtzite GaAs nanowires is characterized by a single and narrow emission peak at 1.52 eV. PMID:26998550

  9. Silver as Seed-Particle Material for GaAs Nanowires--Dictating Crystal Phase and Growth Direction by Substrate Orientation.

    PubMed

    Lindberg, Caroline; Whiticar, Alexander; Dick, Kimberly A; Sköld, Niklas; Nygård, Jesper; Bolinsson, Jessica

    2016-04-13

    Here we investigate the feasibility of silver as seed-particle material to synthesize GaAs nanowires and show that both crystal phase and growth direction can be controlled by choice of substrate orientation. A (111)B substrate orientation can be used to form vertically aligned wurtzite GaAs nanowires and a (100) substrate orientation to form vertically aligned zinc blende GaAs nanowires. A 45-50% yield of vertical nanowire growth is achieved on the (100) substrate orientation without employing any type of surface modification or nucleation strategy to promote a vertical growth direction. In addition, photoluminescence measurements reveal that the photon emission from the silver seeded wurtzite GaAs nanowires is characterized by a single and narrow emission peak at 1.52 eV. PMID:26998550

  10. Clay Mineral: Radiological Characterization

    NASA Astrophysics Data System (ADS)

    Cotomácio, J. G.; Silva, P. S. C.; Mazzilli, B. P.

    2008-08-01

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and 40K in these clay minerals. The objective of this work is to determine the concentrations of 238U, 232Th, 226Ra, 228Ra, 210Pb and 40K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of 238U and 232Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for 226Ra, 228Ra, 210Pb and 40K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906±340 Bq kg-1 for 40K, 40±9 Bq kg-1 for 226Ra, 75±9 Bq kg-1 for 228Ra, 197±38 Bq kg-1 for 210Pb, 51±26 Bq kg-1 for 238U and 55±24 Bq kg-1 for 232Th, considering both kinds of clay.

  11. The Science of Clay

    ERIC Educational Resources Information Center

    Warwick, Sharon

    2005-01-01

    Students' natural curiosity provides a rich opportunity for teachers to make meaningful scientific connections between art and ceramics that will enhance the understanding of both natural forces and scientific aspects at work in the creation of clay artworks. This article discusses the scientific areas of study related to clay, which include…

  12. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2003-01-01

    Part of the 2002 industrial minerals review. The production, consumption, and price of shale and common clay in the U.S. during 2002 are discussed. The impact of EPA regulations on brick and structural clay product manufacturers is also outlined.

  13. Finicky clay divers

    NASA Astrophysics Data System (ADS)

    Cordry, Sean M.

    1998-02-01

    Clay spheres dropped into a dilute vinegar/baking-soda solution accumulate CO2 bubbles on their surfaces. Spheres below a certain size will then float, otherwise they remain sunken. Students must determine the maximum size that will float by considering the net density of the clay/bubble system.

  14. Clay Portrait Boxes

    ERIC Educational Resources Information Center

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  15. Columns in Clay

    ERIC Educational Resources Information Center

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  16. Use of organo-clays in the removal of toxic organics from industrial wastewaters

    SciTech Connect

    Srinivasan, K.R.; Fogler, H.S.

    1987-01-01

    This study describes the development of organo-clays as cost-effective adsorbents for the removal of nonionic, toxic organics from wastewaters. Cetyl pyridinium montmorillonite (CPC-CLAY; an interlayer organo-clay) and Cetyl pyridinium hydroxy aluminum montmorillonite (CPC(HYDAL-CLAY; a predominantly external layer organo-clay) were prepared as model sorbents. Using pentachlorophenol (PCP) as the target organic molecule, our studies show that CPC-HYDAL-CLAY containing 12.0% by weight surface organic carbon is significantly more effective (about 10 times) than CPC-CLAY with 19.2% by weight surface organic carbon. Similar results were obtained with La-CPC-CLAY (12% organic carbon) and CPC-kaolinite (3.0% organic carbon), both of which exhibit surface orientation of organic carbon similar to that of CPC-HYDAL-CLAY. Specifically, the effectiveness of CPC-kaolinite establishes the idea that orientation of surface organic carbon may be as significant as the actual amount. All the three external surface oriented organo-clays studied here are comparable to activated carbon in their sorption potential for PCP. Electrokinetic and adsorption/desorption measurements reveal that in the cases of CPC-HYDAL-CLAY and La-CPC-CLAY, binding of CPC ion to the respective surfaces is of the high affinity and irreversible type and that the endpoint of adsorption may be in the form of a bidimensional aggregate or a ''hemimicelle''.

  17. Equilibrium orientations of non-spherical and chemically anisotropic particles at liquid-liquid interfaces and the effect on emulsion stability.

    PubMed

    Ballard, Nicholas; Bon, Stefan A F

    2015-06-15

    The effective stabilization of emulsions by solid particles, a phenomenon known as Pickering stabilization, is well known to be highly dependent on the wettability and the adhesion energy of the stabilizer employed at the liquid-liquid interface. We present a user-friendly computational model that can be used to determine equilibrium orientations and the adhesion energy of colloidal particles at interfaces. The model determines the free energy profile of particle adsorption at liquid-liquid interfaces using a triangular tessellation scheme. We demonstrate the use of the model, using a variety of anisotropic particles and demonstrate its ability to predict and explain experimental observations of particle behaviour at interfaces. In particular, we show that the concept of hydrophilic lipophilic balance commonly applied to molecular surfactants is insufficient to explain the complexity of the activity of colloidal particles at interfaces. In addition, we show the importance of the knowledge of the free energy adsorption profile of single particles at interfaces and the impact on overall free energy of emulsification of packed ensembles of particles. The delicate balance between optimization of adhesion energy, adsorption dynamics and particle packing is shown to be of great importance in the formation of thermodynamically stable emulsions. In order to use the model, the code is implemented by freely available software that can be readily deployed on personal computers. PMID:25792476

  18. Effect of Melt Convection at Various Gravity Levels and Orientations on the Forces Acting on a Large Spherical Particle in the Vicinity of a Solidification Interface

    NASA Technical Reports Server (NTRS)

    Bune, Andris V.; Sen, Subhayu; Mukherjee, Sundeep; Catalina, Adrian; Stefanescu, Doru M.

    2000-01-01

    Numerical modeling was Undertaken to analyze the influence of both radial and axial thermal gradients on convection patterns and velocities claiming solidification of pure Al and an Al-4 wt% Cu alloy. The objective of the numerical task was to predict the influence of convective velocity on an insoluble particle near a solid/liquid (s/l) interface. These predictions were then be used to define the minimum gravity level (q) required to investigate the fundamental physics of interactions between a particle and a s/l interface. This is an ongoing NASA founded flight experiment entitled "particle engulfment and pushing by solidifying interfaces (PEP)". Steady-state calculations were performed for different gravity levels and orientations with respect to the gravity vector The furnace configuration used in this analysis is the quench module insert (QMI-1) proposed for the Material Science Research Facility (MSRF) on board the International Space Station (ISS). The general model of binary alloy solidification was based on the finite element code FIDAP. At a low g level of 10(exp -4) g(sub o) (g(sub o) = 9.8 m/square s) maximum melt convection was obtained for an orientation of 90 deg. Calculations showed that even for this worst case orientation the dominant forces acting on the particle are the fundamental drag and interfacial forces.

  19. Stress induced permeability anisotropy of Resedimented Boston Blue Clay

    NASA Astrophysics Data System (ADS)

    Adams, Amy L.; Germaine, John T.; Flemings, Peter B.; Day-Stirrat, Ruarri J.

    2013-10-01

    In Resedimented Boston Blue Clay (RBBC), a low-plasticity glacio-marine illitic mudrock, the ratio of the horizontal to vertical permeability (the permeability anisotropy, rk) increases from 1.2 to 1.9 as the porosity decreases from 0.5 to 0.37 and the permeability decreases by more than 1 order of magnitude. Backscattered Scanning Electron Microscope (BSEM) images taken at formation stress levels reveal that particles rotate perpendicular to the axial loading direction by ˜22°, with larger particles rotating more significantly and achieving more uniform alignment than smaller particles. We show experimentally that preferred platy particle orientation can explain our permeability anisotropy measurements. The permeability anisotropy of mechanically compressed mudrocks is minimal, <2.5. We use a novel approach (cubic specimens) to measure the evolution of permeability anisotropy in different directions on the same specimen, unlike most other methods. Modified analytic techniques allow calculation of the permeability anisotropy for a specimen using directional constant head permeability methods. A better understanding of the evolution of permeability anisotropy during sediment burial is important for modeling subsurface transport processes, including hydrocarbon migration and contaminant transport, as well as estimating in situ conditions such as pore pressure, overpressure, and effective stress.

  20. Soil clay content underlies prion infection odds

    USGS Publications Warehouse

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  1. Particle size distribution of typical ceramic raw materials by laser granulometry

    NASA Technical Reports Server (NTRS)

    Wojnarovitsne, I. H.; Lenkel, M.

    1984-01-01

    The principles of the method are explained and the working of the CILAS 715 laser granulometer is described. The particle size distributions of milled glazes, quartz, feldspar and china clay were determined by this instrument and by Andreasen sedimentation. The agreement was good for isometric particles, but the china clay appears finer by sedimentation, because the platelets arrange themselves horizontally during sedimentation, while in the laser granulometer preferred orientation is prevented by circulation between the sample holder and the vibrated and stirred reservoir of the slip.

  2. Black Carbon, The Pyrogenic Clay Mineral?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most soils contain significant amounts of black carbon, much of which is present as discrete particles admixed with the coarse clay fraction (0.2–2.0 µm e.s.d.) and can be physically separated from the more abundant diffuse biogenic humic materials. Recent evidence has shown that naturally occurring...

  3. Molecular interactions alter clay and polymer structure in polymer clay nanocomposites.

    PubMed

    Sikdar, Debashis; Katti, Kalpana S; Katti, Dinesh R

    2008-04-01

    In this work, using photoacoustic Fourier transform infrared spectroscopy (FTIR) we have studied the structural distortion of clay crystal structure in organically modified montmorillonite (OMMT) and polymer clay nanocomposites (PCN). To study the effect of organic modifiers on the distortion of crystal structure of clay, we have synthesized OMMTs and PCNs containing same polymer and clay but with three different organic modifiers (12-aminolauric acid, n-dodecylamine, and 1,12-diaminododecane), and conducted the FTIR study on these PCNs. Our previous molecular dynamics (MD) study on these PCNs reveals that significant nonbonded interactions (van der Waals, electrostatic interactions) exist between the different constituents (polymer, organic modifier, and clay) of nanocomposites. Previous work based on X-ray diffraction (XRD) and differential scanning calorimetry (DSC) on the same set of PCNs shows that crystallinity of polymer in PCNs have changed significantly in comparison to those in pristine polymer; and, the nonbonded interactions between different constituents of PCN are responsible for the change in crystal structure of polymer in PCN. In this work to evaluate the structural distortion of crystal structure of clay in OMMTs and PCNs, the positions of bands corresponding to different modes of vibration of Si-O bonds are determined from the deconvolution of broad Si-O bands in OMMTs and PCNs obtained from FTIR spectra. Intensity and area under the Si-O bands are indicative of orientation of clay crystal structures in OMMTs and PCNs. Significant changes in the Si-O bands are observed from each vibration mode in OMMTs and PCNs containing three different organic modifiers indicating that organic modifiers influence the structural orientation of silica tetrahedra in OMMTs and PCNs. Deconvolution of Si-O bands in OMMTs indicate a band at approximately 1200 cm(-1) that is orientation-dependent Si-O band. The specific changes in intensity and area under this band for

  4. Clays as prebiotic photocatalysts

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lawless, J.; Lahav, N.; Sutton, S.; Sweeney, M.

    1981-01-01

    Clay minerals catalyze peptide bond formation in fluctuating environments. A number of plausible mechanisms have been proposed and tested. The possibility that clays may actually be energizing the reaction by means of electronic excitation, creating mobile or trapped holes and electrons in the lattice, is explored. It has been discovered that clays emit light upon dehydration. The correlation between dehydration-induced, or thermoluminescent, processes and the yield of glycine oligomers after treatments known to affect the luminescent yields is being tested, in an effort to understand the catalytic mechanism

  5. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    PubMed

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-04-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. PMID:24718363

  6. Clay-catalyzed reactions of coagulant polymers during water chlorination

    USGS Publications Warehouse

    Lee, J.-F.; Liao, P.-M.; Lee, C.-K.; Chao, H.-P.; Peng, C.-L.; Chiou, C.T.

    2004-01-01

    The influence of suspended clay/solid particles on organic-coagulant reactions during water chlorination was investigated by analyses of total product formation potential (TPFP) and disinfection by-product (DBP) distribution as a function of exchanged clay cation, coagulant organic polymer, and reaction time. Montmorillonite clays appeared to act as a catalytic center where the reaction between adsorbed polymer and disinfectant (chlorine) was mediated closely by the exchanged clay cation. The transition-metal cations in clays catalyzed more effectively than other cations the reactions between a coagulant polymer and chlorine, forming a large number of volatile DBPs. The relative catalytic effects of clays/solids followed the order Ti-Mont > Fe-Mont > Cu-Mont > Mn-Mont > Ca-Mont > Na-Mont > quartz > talc. The effects of coagulant polymers on TPFP follow the order nonionic polymer > anionic polymer > cationic polymer. The catalytic role of the clay cation was further confirmed by the observed inhibition in DBP formation when strong chelating agents (o-phenanthroline and ethylenediamine) were added to the clay suspension. Moreover, in the presence of clays, total DBPs increased appreciably when either the reaction time or the amount of the added clay or coagulant polymer increased. For volatile DBPs, the formation of halogenated methanes was usually time-dependent, with chloroform and dichloromethane showing the greatest dependence. ?? 2003 Elsevier Inc. All rights reserved.

  7. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Part of the 2003 industrial minerals review. The legislation, production, and consumption of common clay and shale are discussed. The average prices of the material and outlook for the market are provided.

  8. Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

    NASA Technical Reports Server (NTRS)

    Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

    2003-01-01

    A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

  9. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    At present, 150 companies produce common clay and shale in 41 US states. According to the United States Geological Survey (USGS), domestic production in 2005 reached 24.8 Mt valued at $176 million. In decreasing order by tonnage, the leading producer states include North Carolina, Texas, Alabama, Georgia and Ohio. For the whole year, residential and commercial building construction remained the major market for common clay and shale products such as brick, drain tile, lightweight aggregate, quarry tile and structural tile.

  10. Clay Mineral: Radiological Characterization

    SciTech Connect

    Cotomacio, J. G.; Silva, P. S. C.; Mazzilli, B. P

    2008-08-07

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and {sup 40}K in these clay minerals.The objective of this work is to determine the concentrations of {sup 238}U, {sup 232}Th, {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 40}K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay.Measurement for the determination of {sup 238}U and {sup 232}Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 40}K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906{+-}340 Bq kg{sup -1} for {sup 40}K, 40{+-}9 Bq kg{sup -1} for {sup 226}Ra, 75{+-}9 Bq kg{sup -1} for {sup 228}Ra, 197{+-}38 Bq kg{sup -1} for {sup 210}Pb, 51{+-}26 Bq kg{sup -1} for {sup 238}U and 55{+-}24 Bq kg{sup -1} for {sup 232}Th, considering both kinds of clay.

  11. Designing in Clay

    ERIC Educational Resources Information Center

    Nigrosh, Leon I.

    1977-01-01

    What can be done to transform a lump of wet clay into something more than a lump of glaze-fired clay? It is at this point when forming techniques have been mastered that good design becomes most important. Discusses six criteria involved in the search for good design so that students can discover what good design is and how important it is.…

  12. Clay minerals in Alpine Fault gouge: First results from the DFDP-1B pilot hole

    NASA Astrophysics Data System (ADS)

    van der Pluijm, B. A.; Schleicher, A. M.

    2012-12-01

    fabrics in fault gouge support the interpretation that clay fabric development in shallow fault rocks is a function of authigenic mineral growth and not stress-induced particle orientation. The unique localization of smectite in fault gouge indicates that swelling clay minerals may dominate fault behavior at shallow depth, and that temporal and fluid histories may be obtained from study of these fault rocks and samples from planned, deeper drilling.

  13. Investigation of Four Different Laponite Clays as Stabilizers in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chniguir, Mehdi; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-06-21

    Clay-armored polymer particles were prepared by emulsion polymerization in the presence of Laponite platelets that adsorb at the surface of latex particles and act as stabilizers during the course of the polymerization. While Laponite RDS clay platelets are most often used, the choice of the type of clay still remains an open issue that is addressed in the present article. Four different grades of Laponite were investigated as stabilizers in the emulsion polymerization of styrene. First, the adsorption isotherms of the clays, on preformed polystyrene particles, were determined by ICP-AES analysis of the residual clay in the aqueous phase. Adsorption of clay depended on the type of clay at low concentrations corresponding to adsorption as a monolayer. Adsorption of clay particles as multilayers was observed for all the grades above a certain concentration under the considered ionic strength (mainly due to the initiator ionic species). The stabilization efficiency of these clays was investigated during the polymerization reaction (free of any other stabilizer). The clays did not have the same effect on stabilization, which was related to differences in their compositions and in their adsorption isotherms. The different grades led to different polymer particles sizes and therefore to different polymerization reaction rates. Laponite RDS and S482 gave similar results, ensuring the best stabilization efficiency and the fastest reaction rate; the number of particles increased as the clay concentration increased. Stabilization with Laponite XLS gave the same particles size and number as the latter two clays at low clay concentrations, but it reached an upper limit in the number of nucleated polymer particles at higher concentrations indicating a decrease of stabilization efficiency at high concentrations. Laponite JS did not ensure a sufficient stability of the polymer particles, as the polymerization results were comparable to a stabilizer-free polymerization system

  14. Partitioning of Laponite Clay Platelets in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-01-12

    Partitioning of laponite disklike clay platelets between polymer particles and bulk aqueous phase was investigated in Pickering surfactant-free emulsion polymerization of styrene. Adsorption of laponite clay platelets plays an important role in the stabilization of this system, influencing the particle size and the number of particles, and, hence, the reaction rate. Adsorption isotherms show that, while the laponite clay platelets are almost fully exfoliated in water, they form multilayers on the surface of the polymer particles by the end of polymerization, as confirmed by transmission electron microscopy (TEM). This observation is supported by quartz crystal microbalance, conductivity, and TEM measurements, which reveal interactions between the clay and polystyrene, as a function of the ionic strength. The strong adsorption of clay platelets leaves a low residual concentration in the aqueous phase that cannot cause further nucleation of polymer particles, as demonstrated during seeded emulsion polymerization experiments in the presence of a high excess of clay. A Brunauer-Emmett-Teller (BET)-type model for laponite adsorption on polystyrene particles matches the adsorption isotherms. PMID:26653971

  15. Particle Size and Structural Arrangement of Suspended Cohesive Sediments

    NASA Astrophysics Data System (ADS)

    Tan, X.; Zhang, G.; Reed, A. H.; Furukawa, Y.

    2012-12-01

    -montmorillonite flocs; it rarely influences illite flocs. The microstructure of selected clay flocs and clay-EPS flocs was studied via free settling test and electron microscopy (e.g., SEM, TEM) to estimate their physical properties, including settling velocity, density, fractal dimension, porosity, and solids volume fraction. The free settling velocity ranges from 0.05-1 mm/s and their fractal dimension is from ~1.3-2, which indicates their high porosity. One interesting finding is that clay-EPS flocs usually settle slower than pure clay flocs, apparently due to the lower density of EPS molecules. As such, a larger clay-EPS floc may settle slower than a smaller pure clay floc. This contradicts with previous understanding that a larger floc always settle faster than a smaller one. SEM and TEM were conducted on carefully selected individual flocs to characterize the microstructure. Surface features of different types of flocs (e.g., the presence of EPS, particle compactness, porosity, and clay particle orientation) were obtained from SEM. TEM imaging on chemically fixed, stained and sliced floc samples illustrates more detailed features of flocs' interior structure. In addition, a complete series of thin section TEM images were used to reconstruct the 3D image of individual flocs.

  16. Morphology and thermal properties of clay/PMMA nanocomposites obtained by miniemulsion polymerization.

    PubMed

    García-Chávez, Karla I; Hernández-Escobar, Claudia A; Flores-Gallardo, Sergio G; Soriano-Corral, Florentino; Saucedo-Salazar, Esmeralda; Zaragoza-Contreras, E Armando

    2013-06-01

    Miniemulsion polymerization was used as the synthetic method to produce clay/poly(methyl methacrylate) nanocomposites. Two kinds of interfacial interactions clay-polymer particle were observed by electron microscopy, one where the polymer particles are adhered on the surface of the larger fragments of clay, and another where nanometric fragments of clay are encapsulated by polymer particles. Variations in the glass transition temperature (T(g)) and thermomechanical properties of the matrix, as function of clay content, were observed. In particular, at the highest clay loading (1.0 wt%) depression of T(g) and thermomechanical properties were observed. The increased clay-polymer matrix interfacial area appears to be the conditioning factor that determines such behavior. PMID:23541871

  17. NMR imaging and cryoporometry of swelling clays

    NASA Astrophysics Data System (ADS)

    Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

    2010-05-01

    Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic

  18. Inter-layered clay stacks in Jurassic shales

    NASA Technical Reports Server (NTRS)

    Pye, K.; Krinsley, D. H.

    1983-01-01

    Scanning electron microscopy in the backscattered electron mode is used together with energy-dispersive X-ray microanalysis to show that Lower Jurassic shales from the North Sea Basin contain large numbers of clay mineral stacks up to 150 microns in size. Polished shale sections are examined to determine the size, shape orientation, textural relationships, and internal compositional variations of the clays. Preliminary evidence that the clay stacks are authigenic, and may have formed at shallow burial depths during early diagenesis, is presented.

  19. Spectromicroscopy of Fe distributions in clay microcrystals

    SciTech Connect

    Grundl, T.; Cerasari, S.; Garcia, A.

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  20. TEM analysis of the internal structures and mineralogy of Asian dust particles and the implications for optical modeling

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Nousiainen, T.

    2014-07-01

    Mineral dust interacts with incoming/outgoing electromagnetic radiation in the atmosphere. This interaction depends on the microphysical properties of the dust particles, including size, mineral composition, external morphology, and internal structure. Ideally all of these properties should be accounted for in the remote sensing of dust, the modeling of single-scattering properties, and radiative effect assessment. There have been many reports on the microphysical characterizations of mineral dust, but no investigations of the internal structures of individual dust particles. We explored the interiors of Asian dust particles using the combined application of focused ion beam thin-slice preparation and high-resolution transmission electron microscopy. The results showed that individual dust particles consisted of numerous mineral grains, which were organized into several types of internal structure: single and polycrystalline cores of quartz, feldspars, calcite, and amphibole often with oriented clay coatings; individual clay agglomerates of nano-thin clay platelets showing preferred to random orientations common with coarser mineral inclusions; and platy coarse phyllosilicates (muscovite, biotite, and chlorite). Micron to submicron pores were scattered throughout the interior of particles. Clays in the coatings and agglomerates were dominated by nano-thin platelets of the clay minerals of illite-smectite series including illite, smectite, and their mixed layers with subordinate kaolinite and clay-sized chlorite. Submicron iron oxide grains, dominantly goethite, were distributed throughout the clay agglomerates and coatings. Unlike the common assumptions and simplifications, we found that the analyzed dust particles were irregularly shaped with birefringent, polycrystalline, and polymineralic heterogeneous compositions. Accounting for this structural and mineralogical makeup may improve the remote sensing retrieval of dust and the evaluation of radiation effects

  1. TEM analysis of the internal structures and mineralogy of Asian dust particles and the implications for optical modeling

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Nousiainen, T.

    2014-03-01

    Mineral dust interacts with incoming/outgoing electromagnetic radiation in the atmosphere. This interaction depends on the microphysical properties of the dust particles, including size, mineral composition, external morphology, and internal structure. Ideally all these properties should be accounted for in dust remote sensing, the modeling of single-scattering properties, and radiative effect assessment. There have been many reports on the microphysical characterizations of mineral dust, but no investigations of the internal structures or mineral composition of individual dust particles. We explored the interiors of Asian dust particles using the combined application of focused ion beam thin-slice preparation and high-resolution transmission electron microscopy. The results showed that individual dust particles consisted of numerous mineral grains, which were organized into several types of internal structure: single and polycrystalline cores of quartz, feldspars, calcite, and amphibole often with oriented clay coatings; individual clay agglomerates of nano-thin clay platelets showing preferred to random orientations commonly with coarser mineral inclusions; and platy coarse phyllosilicates (muscovite, biotite, and chlorite). Micron to submicron pores were scattered throughout the interior of particles. Clays in the coatings and agglomerates were dominated by nano-thin platelets of the clay minerals of illite-smectite series including illite, smectite, and their mixed layers with subordinate kaolinite and clay-size chlorite. Submicron iron oxide grains, dominantly goethite, were distributed throughout the clay agglomerates and coatings. Unlike the common assumptions and simplifications, we found that the analyzed dust particles were irregularly shaped with birefringent, polycrystalline, and polymineralic heterogeneous compositions. Accounting for this structural and mineralogical makeup may improve the remote sensing retrieval of dust and the evaluation of

  2. Glowing clay: Real time tracing using a suite of novel clay based fluorescent tracers

    NASA Astrophysics Data System (ADS)

    Hardy, Robert; Quinton, John; Pates, Jackie; Coogan, Mike

    2015-04-01

    Clay is one of the most mobile fractions of soil due to its small particle size. It is also known to sorb many chemicals, such as nutrients (notably phosphorus), agrochemicals and heavy metals. The movement of clay is therefore linked with the transport and fate of these substances. A novel fluorescent clay tracing suite has been produced, together with an imaging technique. This suite consists of qualitative clay tracers, using rhodamine based fluorophores, and quantitative clay tracers, using metal based fluorophores. Efforts have also been made to allow integration of commercially available tracers, which are silt and sand sized. The clay tracers exploit the high affinity that montmorillonite has for Rhodamine B and Ru(bpy)3. This allows for an extremely thin layer of the fluorophore to be sorbed onto the clay's surface, in much that same way as materials in the natural environment will bind to clay. The tracer that is produced retains key chemical and physical properties of clay, such as size, shape and density. The retention of these micro-properties results in the retention of macro-properties, such as tendency to aggregate and cracking on drying. Imaging techniques have been developed to analyse these tracers. The imaging system uses diffused laser light to excite the tracer and a modified DSLR camera to image the soil surface. The images have been compiled into a time lapse video showing the movement of clay over the course of a rainfall event. This is the first time that the quantitative movement of clay has been recorded over a soil surface in real time. 4D data can be extracted from the images allowing the spatial location and intensity of tracer to be monitored over time, with mm precision and on the timescale of seconds. As the system can also work with a commercial tracer it is possible to investigate the movement of particles of almost any size and over a range of scales from soil box to hillside. This allows users to access this technique without

  3. Strategies for modulating the luminescence properties of pyronin Y dye-clay films: an experimental and theoretical study.

    PubMed

    Epelde-Elezcano, Nerea; Martínez-Martínez, Virginia; Duque-Redondo, Eduardo; Temiño, Inés; Manzano, Hegoi; López-Arbeloa, Iñigo

    2016-03-28

    The aggregation process, particularly the type and extent of pyronin Y (PY) laser dye intercalated into supported thin films of two different trioctahedral clay minerals, LAPONITE® (Lap) and saponite (Sap), at different dye loadings is studied: (i) experimentally by means of electronic absorption and fluorescence spectroscopy and (ii) theoretically by modeling the distribution of the dye into the interlayer space of these layered silicates. According to the results, H-type aggregates of the PY dye are favoured in Lap even at very low dye loading while a much lower molecular aggregation tendency in J-type geometry is found in Sap films. The aggregation state of PY in each clay mineral is likely attributed to different strengths of the electrostatic interactions between the dye and the layered silicate in the interlayer space due to their distinctive charge localization on the TOT clay layer (i.e. net negative charge in octahedral layers for Lap vs. in tetrahedral layers for Sap), as well as the interlaminar water distribution in each clay mineral, although other factors such as their CEC and particle size cannot be discarded. To reduce the huge aggregation processes of PY dye into Lap films, surfactant molecules (DDTAB) are co-adsorbed in the interlayer space of the clay. At an optimized surfactant concentration, the aggregation tendency of PY dye in Lap is considerably reduced enormously improving the fluorescence efficiency of the PY/Lap films. Finally, by means of anisotropic response from the hybrid films to the plane of the polarized light, the orientation of the PY molecules with respect to the normal axis of the clay layer is determined for all films (with and without surfactant) at different dye loadings. PMID:26954470

  4. Mapping and Quantifying Surface Charges on Clay Nanoparticles.

    PubMed

    Liu, Jun; Gaikwad, Ravi; Hande, Aharnish; Das, Siddhartha; Thundat, Thomas

    2015-09-29

    Understanding the electrical properties of clay nanoparticles is very important since they play a crucial role in every aspect of oil sands processing, from bitumen extraction to sedimentation in mature fine tailings (MFT). Here, we report the direct mapping and quantification of surface charges on clay nanoparticles using Kelvin probe force microscopy (KPFM) and electrostatic force microscopy (EFM). The morphology of clean kaolinite clay nanoparticles shows a layered structure, while the corresponding surface potential map shows a layer-dependent charge distribution. More importantly, a surface charge density of 25 nC/cm(2) was estimated for clean kaolinite layers by using EFM measurements. On the other hand, the EFM measurements show that the clay particles obtained from the tailings demonstrate a reduced surface charge density of 7 nC/cm(2), which may be possibly attributed to the presence of various bituminous compounds residing on the clay surfaces. PMID:26352908

  5. Rattles of Clay.

    ERIC Educational Resources Information Center

    Banning, Donna

    1983-01-01

    Using the rattles of Native American cultures as inspiration, students used pinching, coiling, and slab and molding techniques to form the bodies of rattles and clay pellets for sound. Surface decoration included glazed and unglazed areas as well as added handles, feathers, and leather. (IS)

  6. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the common clay and shale industry is provided. In 2000, U.S. production increased by 5 percent, while sales or use declined to 23.6 Mt. Despite the slowdown in the economy, no major changes are expected for the market.

  7. Clay Animals and Their Habitats

    ERIC Educational Resources Information Center

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  8. Adsorption coefficients for TNT on soil and clay minerals

    NASA Astrophysics Data System (ADS)

    Rivera, Rosángela; Pabón, Julissa; Pérez, Omarie; Muñoz, Miguel A.; Mina, Nairmen

    2007-04-01

    To understand the fate and transport mechanisms of TNT from buried landmines is it essential to determine the adsorption process of TNT on soil and clay minerals. In this research, soil samples from horizons Ap and A from Jobos Series at Isabela, Puerto Rico were studied. The clay fractions were separated from the other soil components by centrifugation. Using the hydrometer method the particle size distribution for the soil horizons was obtained. Physical and chemical characterization studies such as cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed for the soil and clay samples. A complete mineralogical characterization of clay fractions using X-ray diffraction analysis reveals the presence of kaolinite, goethite, hematite, gibbsite and quartz. In order to obtain adsorption coefficients (K d values) for the TNT-soil and TNT-clay interactions high performance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil was described by the Langmuir model. A higher adsorption was observed in the Ap horizon. The Freundlich model described the adsorption process for TNT-clay interactions. The affinity and relative adsorption capacity of the clay for TNT were higher in the A horizon. These results suggest that adsorption by soil organic matter predominates over adsorption on clay minerals when significant soil organic matter content is present. It was found that, properties like cation exchange capacity and surface area are important factors in the adsorption of clayey soils.

  9. SAXS Study of Reversibly Crosslinked Isotactic Polypropylene/clay Nanocomposites

    SciTech Connect

    Bouhelal, S.; Cagiao, M; Benachour, D; Djellouli, B; Rong, L; Hsiao, B; Baltá-Calleja, F

    2010-01-01

    A new route based on reversibly crosslinking reactive extrusion is applied for the development of iPP/clay nanocomposites. Analysis of small-angle X-ray scattering (SAXS) reflections of isotactic polypropylene (iPP)/clay nanocomposites, prepared by two different mixing and chemical crosslinking methods (i.e., conventional and in situ), is presented and results are compared with preceding wide-angle X-ray diffraction (WAXD) results. It is shown that the presence of clay significantly affects the value of long spacing in iPP, as well as the coherence length of lamellar stacks. Results show that the size of the coherently diffracting nanodomains decreases in two stages, first rapidly and then slowly as a function of increasing clay content. This can be attributed to the influence of confined iPP lamellae under the effect of rising number of clay particles. The appearance of the {gamma}-crystalline form in the crosslinked iPP/clay nanocomposites is related with the difficulty in chain folding of iPP chains introduced by the chemical crosslinking process, as well as by the presence of clay particles.

  10. Multishell Au/Ag/SiO2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

    SciTech Connect

    Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier; Fang, Ning

    2015-04-07

    In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of the hybrid nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.

  11. Impact of Ni(OH)(2) platelike particles on lamellar surfactant mesophases and the orientation of their mixtures under elongational flow.

    PubMed

    Qazi, S Junaid S; Rennie, Adrian R; Tucker, Ian; Penfold, Jeff; Grillo, Isabelle

    2011-09-01

    This article describes the behavior under elongational flow of mixtures of lamellar fragments and platelike colloidal particles. Mixtures of a dialkyl chain cationic surfactant, DHTAC (15 wt %), and the nonionic surfactant Brij 97 (0.5 wt %) form dispersions of lamellar phase fragments, and these were studied in the presence of smaller platelike colloidal particles of Ni(OH)(2) stabilized with sodium polyacrylate. Small-angle neutron scattering was used to follow the changes in the lamellar phase fragments in the mixture under elongational flow. The addition of a small fraction of the Ni(OH)(2) dispersion resulted in significantly increased viscosity and reduced the structure and size of the lamellar fragments, and this effect was further enhanced because of the flow induced alignment. The behavior of the mixture under elongational flow is described, and the induced orientation is discussed in terms of order parameters at the different positions using spatially resolved small-angle scattering. The effect of flow rate on the orientational alignment in the mixture is also described. PMID:21780741

  12. Weak Polyelectrolyte-Clay Assemblies: Physical Mechanisms of Biological Response

    NASA Astrophysics Data System (ADS)

    Sukhishvili, Svetlana; Pavlukhina, Svetlana; Zhuk, Iryna

    2014-03-01

    We report on a highly efficient, non-leachable antibacterial coating, consisting of an ultrathin nanocomposite hydrogel capable of hosting, protecting and delivering antibiofilm agents in response to bacterial infection. Constructed using layer-by-layer (LbL) deposition of clay nanoplatelets and a weak polyelectrolyte and loaded with an antimicrobial agent (AmA), the coatings was highly resistant to colonization by Staphylococcus aureus. The high antibiofilm activity of the coating results from a combination of highly localized, bacteria-triggered AmA release and hydrogel swelling, as well as retention of AmA by clay nanoplatelets. We discuss the dependence of rheological and swelling properties of weak polyelectrolyte-clay assemblies on film thickness, clay platelet orientation and environmental pH.

  13. Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

    PubMed

    Moran, Anthony R; Hettiarachchi, Hiroshan

    2011-07-01

    Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

  14. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    within the host rock and the undeformed sample shows that the sample underwent compaction prior shearing that results in a change of power law exponent of the pore size distribution within the clay matrix and a slight reorientation of clastic grains' long axis perpendicular to σ1. Microstructures in the shear zone indicate ductile behavior before the specimen's failure. Deformation mechanisms are bending of clay plates and sliding along clay-clay contacts. Strain is strongly localised in thin, anastomosing zones of strong preferred orientation, producing slickensided shear surfaces common in shallow clays. There is no evidence for intragranular cracking.We propose that the deformation localizes in regions without hard quartz grains.

  15. Clay at Nili Fossae

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This image of the Nili Fossae region of Mars was compiled from separate images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the High-Resolution Imaging Science Experiment (HiRISE), two instruments on NASA's Mars Reconnaissance Orbiter. The images were taken at 0730 UTC (2:30 a.m. EDT) on Oct. 4, 2006, near 20.4 degrees north latitude, 78.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36 to 3.92 micrometers, and shows features as small as 18 meters (60 feet) across. HiRISE's image was taken in three colors, but its much higher resolution shows features as small as 30 centimeters (1 foot) across.

    CRISM's sister instrument on the Mars Express spacecraft, OMEGA, discovered that some of the most ancient regions of Mars are rich in clay minerals, formed when water altered the planet's volcanic rocks. From the OMEGA data it was unclear whether the clays formed at the surface during Mars' earliest history of if they formed at depth and were later exposed by impact craters or erosion of the overlying rocks. Clays are an indicator of wet, benign environments possibly suitable for biological processes, making Nili Fossae and comparable regions important targets for both CRISM and HiRISE.

    In this visualization of the combined data from the two instruments, the CRISM data were used to calculate the strengths of spectral absorption bands due to minerals present in the scene. The two major minerals detected by the instrument are olivine, a mineral characteristic of primitive igneous rocks, and clay. Areas rich in olivine are shown in red, and minerals rich in clay are shown in green. The derived colors were then overlayed on the HiRISE image.

    The area where the CRISM and HiRISE data overlap is shown at the upper left, and is about 5 kilometers (3 miles) across. The three boxes outlined in blue are enlarged to show how the different minerals in the scene match up with different landforms. In the image

  16. Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

    SciTech Connect

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng

    2012-07-01

    Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

  17. Mechanical dispersion of clay from soil into water: readily-dispersed and spontaneously-dispersed clay

    NASA Astrophysics Data System (ADS)

    Czyż, Ewa A.; Dexter, Anthony R.

    2015-01-01

    A method for the experimental determination of the amount of clay dispersed from soil into water is described. The method was evaluated using soil samples from agricultural fields in 18 locations in Poland. Soil particle size distributions, contents of organic matter and exchangeable cations were measured by standard methods. Sub-samples were placed in distilled water and were subjected to four different energy inputs obtained by different numbers of inversions (end-over-end movements). The amounts of clay that dispersed into suspension were measured by light scattering (turbidimetry). An empirical equation was developed that provided an approximate fit to the experimental data for turbidity as a function of number of inversions. It is suggested that extrapolation of the fitted equation to zero inversions enables the amount of spontaneously-dispersed clay to be estimated. This method introduces the possibility of replacing the existing subjective, qualitative method of determining spontaneously-dispersed clay with a quantitative, objective method. Even though the dispersed clay is measured under saturated conditions, soil samples retain a `memory' of the water contents at which they have been stored.

  18. Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Niknezhad, Setareh

    The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted

  19. Quantitative mineralogical analysis of small samples of china clay using x ray diffractometry.

    PubMed

    Salt, P D

    1985-09-01

    The quantitative mineralogical analysis of small samples (less than 20 mg) of china clay has been investigated using x ray diffractometry to determine kaolinite, mica, quartz, and feldspar. A method has been developed and applied to the quantitative analysis of airborne dust samples and of other small discrete samples. Determinations were made either on samples after collection on a membrane filter or on samples after deposition from aqueous suspension on to a silver substrate. Quantitative analysis was hindered by preferred orientation of the kaolinite and of the mica particles that occurs when using these methods of specimen preparation. Quartz and feldspar were determined direct from prepared calibration graphs. Preferred orientation of the mica particles leads to serious interference with the most sensitive quartz x ray diffraction peak which, if not recognised, will result in an overestimation of the quartz content. Kaolinite and mica were determined from the ratio of their most intense x ray diffraction peak areas to overcome the preferred orientation effects observed for these two minerals. During the investigation, the opportunity arose for comparative measurements of quartz contents of airborne dust samples with the Occupational Medicine and Hygiene Laboratories of the Health and Safety Executive. The mass of specimen examined varied between 0.8 mg and 20 mg and the quartz contents varied between 0.1% and 1.2%. The comparative results were in good agreement. PMID:4041392

  20. Elastic Properties of Clay Minerals

    NASA Astrophysics Data System (ADS)

    Vanorio, T.; Prasad, M.; Nur, A.

    2001-12-01

    We present ultrasonic P- and S-waves velocity measurements on pure clay samples using three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain density values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was increased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (μ ) moduli for kaolinite, montmorillonite, and smectite; the values range between 6-12 GPa for K and 4-6 GPa for μ , respectively. Using these clay moduli values in effective medium and granular porous media models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstones fairly well. Experimental results also showed that water interlayers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.

  1. Green Clay Minerals

    NASA Astrophysics Data System (ADS)

    Velde, B.

    2003-12-01

    Color is a problem for scientific study. One aspect is the vocabulary one used to describe color. Mint green, bottle green, and Kelly green are nice names but not of great utility in that people's physical perception of color is not always the same. In some industries, such as colored fabric manufacture, current use is to send a set of standard colors which are matched by the producer. This is similar to the use of the Munsell color charts in geology. None of these processes makes use of physical optical spectral studies. The reason is that they are difficult to obtain and interpret. For a geologist, color is very important but we rarely have the possibility to standardize the method of our color perception. One reason is that color is both a reflective and transmission phenomenon. The thickness of the sample is critical to any transmission characteristics. Hence, a field color determination is different from one made by using a petrographic microscope. Green glauconite in a hand specimen is not the same color in 30 μm thick thin section seen with a microscope using transmitted light.A second problem is that color in a spectral identification is the result of several absorption emissions,with overlapping signal, forming a complicated spectrum. Interpretation depends very greatly on the spectrum of the light source and the conditions of transmission-reflection of the sample. As a result, for this text, we will not attempt to analyze the physical aspect of green in green clays. In the discussion which follows, reference is made concerning color, to thin section microscopic perception.Very briefly, green clay minerals are green, because they contain iron. This is perhaps not a great revelation to mineralogists, but it is the key to understanding the origin and stability of green clay minerals. In fact, iron can color minerals either red or green or in various shades of orange and brown. The color most likely depends upon the relative abundance of the iron ion valence

  2. Electric birefringence anomaly of solutions of ionically charged anisometric particles.

    PubMed

    Hoffmann, H; Gräbner, Dieter

    2015-02-01

    The term "electric birefringence anomaly" is known as the electric birefringence (EB) signal that occurs in solutions of ionically charged anisometric particles in a narrow concentration region. The signal is of opposite sign to the normal birefringence that occurs below and above this narrow concentration region. The normal electric birefringence signals in the dilute and more concentrated regions are due to the orientation of the particles in the direction of the applied electric field. The origin for the anomalous signal was not completely understood until now. The article summarises previous results in which the anomalous results had been observed but not well understood. It shows that the birefringence anomaly occurs in systems as diverse as micellar solutions, polyelectrolytes, solutions of clays, viruses and fibres. In all these systems the anomaly signals are present at the concentration when the length of the colloidal particles including the thickness of the electric double layer are about the same as the mean distance between the colloidal particles. Under these conditions the electric double layers of the particles overlap along the main axis of the particles but not in the direction across the particles. As a consequence of this situation a dipole is built up across the particles by the migration of the counter-ions of the particles in the electric field and this dipole leads to an orientation of the particles perpendicular to the electric field. The anomalous signal can usually be observed simultaneously with the normal signal. The amplitude of the anomalous signal can be larger than the amplitude of the normal signal. As a consequence the total birefringence changes its sign in the anomalous concentration region. The anomaly signal of the clays can also be explained by a fluctuating dipole around the particles, which is due to the fact that the centre of the ionic charges of the particles does not fall on the centre of the ionic charge of the counter

  3. Novel convergence-oriented approach for evaluation and optimization of workflow in single-particle two-dimensional averaging of electron microscope images.

    PubMed

    Moriya, Toshio; Mio, Kazuhiro; Sato, Chikara

    2013-01-01

    Three-dimensional (3D) protein structures facilitate the understanding of their biological functions and provide valuable information for developing medicines. Single-particle analysis (SPA) from electron microscopy (EM) is a structure determination method suitable for macromolecules. To achieve a high resolution using combinations of several SPA software packages, 'workflow' optimization and comparative evaluation by scoring results are essential. Two-dimensional (2D) averaging is a key step for 3D reconstruction. The integrated convergence-evaluation oriented system (IC-EOS) proposed here provides an effective tool for customizing 2D averaging. This assesses the behavior and characteristics of workflows and evaluates the convergence of iteration steps without human intervention. We chose five base measurements for quantifying convergence: resolution, variance, similarity, shift-distance and rotation-angle. Curve fitting to history graphs scored their stability. We call this score 'fluctuation'. The number of particle images discarded from the library and the number of classification groups were examined to see their effects on optimization levels and fluctuation of measurements, allowing the IC-EOS to select the most appropriate workflow for the target. A case study using a bacterial sodium channel and a simulation study using GroEL showed that resolution of 2D averaging improved with relatively stricter particle selection. With fewer groups, resolutions of class averages improved, but similarities between class-averages and their constituent particle images degraded. Fluctuation was useful for selecting adequate conditions, even when achieved values alone were not conclusive. The vote method, using fluctuation, was robust against noise and enabled a decision without exhaustive search trials. Thus, the IC-EOS is a step toward full automation of SPA. PMID:23625506

  4. Heteroaggregation of Silver Nanoparticles with Clay Minerals in Aqueous System

    NASA Astrophysics Data System (ADS)

    Liu, J.; Burrow, E.; Hwang, Y.; Lenhart, J.

    2013-12-01

    Nanoparticles are increasingly being used in industrial processes and consumer products that exploit their beneficial properties and improve our daily lives. Nevertheless, they also attract attention when released into natural environment due to their potential for causing adverse effects. The fate and transport of nanoparticles in aqueous systems have been the focus of intense study. However, their interactions with other natural particles have received only limited attention. Clay minerals are ubiquitous in most aquatic systems and their variably charged surfaces can act as deposition sites that can alter the fate and transport of nanoparticles in natural aqueous environments. In this study, we investigated the homoaggregation of silver nanoparticles with different coating layers and their heteroaggregation behavior with clay minerals (illite, kaolinite, montmorillonite) in neutral pH solutions. Silver nanoparticles with a nominal diameter of 80 nm were synthesized with three different surface coating layers: uncoated, citrate-coated and Tween-coated. Illite (IMt-2), kaolinite (KGa-2), and montmorillonite (SWy-2) were purchased from the Clay Mineral Society (Indiana) and pretreated to obtain monocationic (Na-clay) and dicationic (Ca-clay) suspensions before the experiments. The change in hydrodynamic diameter as a function of time was monitored using dynamic light scattering (DLS) measurements in order to evaluate early stage aggregation as a function of electrolyte concentration in both the homo- and heteroaggregation scenarios. A shift in the critical coagulation concentration (CCC) values to lower electrolyte concentrations was observed in binary systems, compared to single silver nanoparticle and clay systems. The results also suggest more rapid aggregation in binary system during the early aggregation stage when compared to the single-particle systems. The behavior of citrate-coated silver nanoparticles was similar to that of the bare particles, while the

  5. Studies on structural properties of clay magnesium ferrite nano composite

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Singh, Mandeep; Jeet, Kiran; Kaur, Rajdeep

    2015-08-01

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m2/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  6. Studies on structural properties of clay magnesium ferrite nano composite

    SciTech Connect

    Kaur, Manpreet Singh, Mandeep; Jeet, Kiran Kaur, Rajdeep

    2015-08-28

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m{sup 2}/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  7. Microbe-Clay Mineral Reactions and Characterization Techniques

    NASA Astrophysics Data System (ADS)

    Dong, H.; Zhang, G.; Ji, S.; Jaisi, D.; Kim, J.

    2008-12-01

    Clays and clay minerals are ubiquitous in soils, sediments, and sedimentary rocks. They play an important role in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. The changes in the oxidation state of the structural iron in clay minerals, in part, control their physical and chemical properties in natural environments, such as clay particle flocculation, dispersion, swelling, hydraulic conductivity, surface area, cation and anion exchange capacity, and reactivity towards organic and inorganic contaminants. The structural ferric iron [Fe(III)] in clay minerals can be reduced either chemically or biologically. Many different chemical reductants have been tried, but the most commonly used agent is dithionite. Biological reductants are bacteria, including dissimilatory iron reducing prokaryotes (DIRP) and sulfate-reducing bacteria (SRB). A wide variety of DIRP have been used to reduce ferric iron in clay minerals, including mesophilic, thermophilic, and hyperthermophilic prokaryotes. Multiple clay minerals have been used for microbial reduction studies, including smectite, nontronite (iron-rich smectite variety), illite, illite/smectite, chlorite, and their various mixtures. All these clay minerals are reducible by microorganisms under various conditions with smectite (nontronite) being the most reducible. The reduction extent and rate of ferric iron in clay minerals are measured by wet chemistry, and the reduced clay mineral products are typically characterized with chemical methods, X-ray diffraction, scanning and transmission electron microscopy, Mössbauer spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), UV-vis spectroscopy, and synchrotron-based techniques (such as EXAFS). Microbially reduced smectites (nontronites) have been found to be reactive in reducing a variety of organic and inorganic contaminants. Degradable organic contaminants include pesticides

  8. Porous networks derived from synthetic polymer-clay complexes

    SciTech Connect

    Carrado, K.A.; Thiyagarajan, P.; Elder, D.L.

    1995-05-12

    Synthetic hectorites were hydrothermally crystallized with direct incorporation of a cationic polymer poly(dimethyl diallyl ammonium chloride) (PDDA), and two neutral cellulosic polymers hydroxypropyl methylcellulose (HPMC) and hydroxyethyl cellulose (HEC). Synthetic PDDA-hectorite displays the lowest d-spacing at 15.8 {Angstrom} along with less polymer incorporation (7.8 wt % organic) than the neutral polymers (18--22 wt % organic). Thermal analysis and small angle neutron scattering were used to further examine the polymer-clay systems. Clay platelets of the largest size and best stacking order occur when cationic PDDA polymer is used. PDDA also enhances these properties over the crystallites prepared for a control mineral, where no polymer is used. HEC acts to aggregate the silica, leaving less to react to form clay. The clay platelets which result from HEC are small, not stacked to a large degree, and oriented randomly. Neutral HPMC acts more like cationic PDDA in that larger clay platelets are allowed to form. The extended microstructure of the clay network remains undisturbed after polymer is removed by calcination. When no polymer is used, the synthetic hectorite has a N{sub 2} BET surface area of 200 M{sup 2}/gm, even after calcination. This increases by 20--50% for the synthetic polymer-hectorites after the polymer is removed by calcination.

  9. Experimental study of Human Adenoviruses interactions with clays

    NASA Astrophysics Data System (ADS)

    Bellou, Maria; Syngouna, Vasiliki; Paparrodopoulos, Spyros; Vantarakis, Apostolos; Chrysikopoulos, Constantinos

    2014-05-01

    Clays are used to establish low permeability liners in landfills, sewage lagoons, water retention ponds, golf course ponds, and hazardous waste sites. Human adenoviruses (HAdVs) are waterborne viruses which have been used as viral indicators of fecal pollution. The objective of this study was to investigate the survival of HAdV in static and dynamic clay systems. The clays used as a model were crystalline aluminosilicates: kaolinite and bentonite. The adsorption and survival of HAdVs onto these clays were characterized at two different controlled temperatures (4 and 25o C) under static and dynamic batch conditions. Control tubes, in the absence of clay, were used to monitor virus inactivation due to factors other than adsorption to clays (e.g. inactivation or sorption onto the tubes walls). For both static and dynamic batch experiments, samples were collected for a maximum period of seven days. This seven day time - period was determined to be sufficient for the virus-clay systems to reach equilibrium. To infer the presence of infectious HAdV particles, all samples were treated with Dnase and the extraction of viral nucleid acid was performed using a commercial viral RNA kit. All samples were analyzed by Real - Time PCR which was used to quantify viral particles in clays. Samples were also tested for virus infectivity by A549 cell cultures. Exposure time intervals in the range of seven days (0.50-144 hours) resulted in a load reduction of 0.74 to 2.96 logs for kaolinite and a reduction of 0.89 to 2.92 for bentonite. Furthermore, virus survival was higher onto bentonite than kaolinite (p

  10. Synchrotron X-ray Scattering from Self-organized Soft Nanostructures in Clays

    NASA Astrophysics Data System (ADS)

    Fossum, J. O.

    2009-04-01

    . Gog, C. Venkataraman, Observations of orientational ordering in aqueous suspensions of a nano-layered silicate, ENERGY The International Journal 30, 873 (2005). 2. D. M. Fonseca, Y. Méheust, J. O. Fossum, K. D. Knudsen, K. J. Måløy and K. P. S. Parmar, Phase behavior of platelet-shaped nanosilicate colloids in saline solutions: A small-angle X-ray scattering study J. Appl. Cryst. 40 292 (2007) 3. E. N. de Azevedo, M. Engelsberg, J. O. Fossum, R. E. de Souza, Anisotropic water diffusion in nematic self-assemblies of clay nano-platelets suspended in water, Langmuir 23, 5100 (2007) 4. Nils Ivar Ringdal, Master thesis, Department of Physics, NTNU (2008) 5. J.O. Fossum, Y. Meheust, K.P.S. Parmar, K.D. Knudsen, K.J. Maloy, D.d.M. Fonseca, Intercalation-enhanced electric polarization and chain formation of nano-layered particles, Europhys. Lett., 74, 438 (2006), and in the Scientific Highlights 2006 of the European Synchrotron Radiation Facility - ESRF (2007) 6. K.P.S. Parmar, Y. Meheust, B. Schelderupsen and J.O. Fossum, Electrorheological suspensions of laponite in oil: rheometry studies, Langmuir 24,1814 (2008) 7. F. Bergaya, B. K. G. Theng, and G. Lagaly, editors. Handbook of Clay Science. Elsevier (2006)

  11. Enhanced photodegradation of organic dyes adsorbed on a clay.

    PubMed

    Tani, Seiji; Yamaki, Hiroshi; Sumiyoshi, Azumi; Suzuki, Yasutaka; Hasegawa, Shinya; Yamazaki, Suzuko; Kawamata, Jun

    2009-01-01

    The interaction of three photoactive organic dyes, Rhodamine B, Rhodamine 6G and a stilbazolium derivative 4'-dimethylamino-N-methyl-4-stilbazolium with synthetic sodium-saponite has been examined by UV-visible absorption spectroscopy. In all cases, bathochromic shifts and the reduction of peak absorbance for the dyes were observed in the absorption spectra at a low dye concentration (25% adsorption of the cation exchange capacity (CEC) of the clay), although the shape and the width of their absorption bands were similar to those in aqueous solution. This absorption behavior indicates that the organic dye molecules adsorbed onto the surface of the negatively charged clay particles and the adsorbed molecules were well dispersed. The photodegradation of the organic dyes in aqueous solution and in the clay suspension has been also examined by the irradiation of a laser beam at a wavelength of 532 nm. We have found that the hybridization of the organic dyes with the exfoliated clay particles largely enhanced a photodegradation. The clay particles acted as a catalyst even at a high concentration such as approximately 300% of CEC. PMID:19441365

  12. Using the Complete Nano Engineering Geological Spectrum to Assess the Performance of Clay Barriers

    NASA Astrophysics Data System (ADS)

    Schmitz, Robrecht M.; Schroeder, Christian; Thorez, Jacques; Charlier, Robert

    Clays are geomaterials used in various (over 100) applications in our society. The more common geotechnical applications are clay barriers to contain waste, slurry walls etc. But even if clays are not used as construction material, the engineering geologist encounters them frequently during construction of e.g. foundations and tunnels. As clays are end products of the weathering of silicate geomaterials they are stable as such, but within this group of clay minerals, geotechnical properties vary enormously. Some of these variations are due to chemo-plasticity e.g. reflected in the effect of the composition of the pore fluid on the mechanical properties of clay. One approach to deal with these chemo plastic effects is to separate them according to the scale or level on which they are acting. In clays one can discern the level of the clay silicate sheets (TOT or TO), the clay interlayer level and the clay particles level. This contribution aims to show how an analysis of the processes on these three levels can help to assess the geotechnical properties of clays in contact with various fluids.

  13. Mineral resource of the Month: Clay

    USGS Publications Warehouse

    Virta, Robert L.

    2010-01-01

    Clays were one of the first mineral commodities used by people. Clay pottery has been found in archeological sites that are 12,000 years old, and clay figurines have been found in sites that are even older.

  14. Elastic Properties of Clay Minerals

    NASA Astrophysics Data System (ADS)

    Vanorio, T.; Prasad, M.; Nur, A.

    We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain den- sity values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was in- creased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (µ) moduli for kaolinite, montmorillonite, and smec- tite; the values range between 6-12 GPa for K and 4-6 GPa for µ, respectively. Using these clay moduli values in effective medium and granular porous media (theories) models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstone fairly well. Experimental results also showed that water interlay- ers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.

  15. Clay energetics in chemical evolution

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.

    1986-01-01

    Clays have been implicated in the origin of terrestrial life since the 1950's. Originally they were considered agents which aid in selecting, concentrating and promoting oligomerization of the organic monomeric substituents of cellular life forms. However, more recently, it has been suggested that minerals, with particular emphasis on clays, may have played a yet more fundamental role. It has been suggested that clays are prototypic life forms in themselves and that they served as a template which directed the self-assembly of cellular life. If the clay-life theory is to have other than conceptual credibility, clays must be shown by experiment to execute the operations of cellular life, not only individually, but also in a sufficiently concerted manner as to produce some semblance of the functional attributes of living cells. Current studies are focussed on the ability of clays to absorb, store and transfer energy under plausible prebiotic conditions and to use this energy to drive chemistry of prebiotic relevance. Conclusions of the work are applicable to the role of clays either as substrates for organic chemistry, or in fueling their own life-mimetic processes.

  16. Preparation and Properties of Clay/SEBS Intercalated Composites

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tomohiro; Yamada, Eisuke

    Clay/polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymer (SEBS) intercalated composites were prepared by melt-blending. The clays were a pristine montmorillonite (Mt) and three organically modified montmorillonites (organo-Mts) with different amounts of distearyldimethylammonium (D18) cation. The amounts of D18 were 50, 70 and 100% of the cation exchange capacity (denoted as D18Mt(50), D18Mt(70) and D18Mt(100), respectively). The clay/SEBS composites were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD). The dynamic mechanical analysis (DMA) and the tensile properties were also examined. The size of agglomerated clay particles decreased with the increasing amount of D18. The FE-SEM image of D18Mt(100)/SEBS revealed that the clay particles were dispersed at the sub-μm level (100-500 nm). The XRD patterns suggested that the SEBS chains were inserted into the interlayers of the organo-Mts. The DMA curves indicated that the addition of the organo-Mts produced an increase in the storage modulus in the rubbery plateau region, but a slight decrease in the glass transition temperature of the polystyrene domains. The tensile properties of the organo-Mt/SEBS composites were higher than those of the unmodified Mt/SEBS. D18Mt(100)/SEBS displayed an improved tensile modulus, tear strength and hardness compared to pure SEBS, without sacrificing the tensile strength and elongation at break.

  17. Influence of Clay Content, Mineralogy and Fabric On Radar Frequency Response of Aquifer Materials

    NASA Astrophysics Data System (ADS)

    West, L. J.; Handley, K.

    High frequency electromagnetic methods such as ground penetrating radar (GPR) and time domain reflectometry (TDR) are widely employed to measure water saturation in the vadose zone and water filled porosity in the saturated zone. However, previous work has shown that radar frequency dielectric properties are strongly influenced by clay as well as by water content. They have also shown that that the dielectric response of clay minerals is strongly frequency dependent, and that even a small proportion of clay such as that present in many sandstone aquifers can have a large effect at typi- cal GPR frequencies (around 100MHz). Hence accurate water content/porosity deter- mination requires clay type and content to be taken into account. Reported here are dielectric measurements on clay-sand mixtures, aimed at investigating the influence of clay mineralogy, particle shape, and the geometrical arrangement of the mixture constituents on GPR and TDR response. Dielectric permittivity (at 50-1000MHz) was measured for mixtures of Ottawa Sand and various clay minerals or clay size quartz rock flour, using a specially constructed dielectric cell. Both homogeneous and layered mixtures were tested. The influence of pore water salinity, clay type, and particle arrangement on the dielectric response is interpreted in terms of dielectric dispersion mechanisms. The appropriateness of var- ious dielectric mixing rules such as the Complex Refractive Index Method (CRIM) for determination of water content or porosity from field GPR and TDR data are dis- cussed.

  18. Treatment with coated layer double hydroxide clays decreases the toxicity of copper-contaminated water.

    PubMed

    Blake, Deanne; Nar, Mangesh; D'Souza, Nandika Anne; Glenn, J Brad; Klaine, Stephen J; Roberts, Aaron P

    2014-05-01

    Copper is a common pollutant found in watersheds that exerts toxic effects on both invertebrates and vertebrates. Layer double hydroxide (LDH) clays are able to adsorb a wide range of contaminants through ion-exchange mechanisms. Coating LDH clays with various materials alters the aggregation of clay particles into the nano-size range, thus increasing relative surface area and offering great potential for contaminant remediation. The goal of this study was to determine if treatment with coated LDH clays decreases the toxicity of copper-containing solutions to Daphnia magna. Four LDH clays with different coatings used to alter hydrophobicity were as follows: used: Na(+) montmorillonite, Zn-Al LDH-nitrate, Zn-Al LDH-stearate, and Zn-Al LDH-carbonate. It was determined that coated LDH clays decreased copper toxicity by decreasing bioavailability and that smaller aggregate sizes decreased bioavailability the most. 96 h LC50 values increased by as much as 4.2 times with the treatment of the solutions with 100 mg/L LDH clay. Copper analysis of the clay and solutions indicated that the clays work by decreasing copper bioavailability by way of a binding mechanism. Coated LDH clays hold promise as a small-scale remediation tool or as an innovative tool for toxicity identification and evaluation characterization of metals. PMID:24442186

  19. Processes and controls in swelling anhydritic clay rocks

    NASA Astrophysics Data System (ADS)

    Mutschler, Thomas; Blum, Philipp; Butscher, Christoph

    2015-04-01

    Referring to the swelling of anhydritic clay rocks in tunneling, Leopold Müller-Salzburg noted in the third volume on tunneling of his fundamental text book on rock engineering that "a truly coherent explanation of these phenomena is still owing" (Müller-Salzburg 1978, p. 306). This valuation is still true after more than three decades of research in the field of swelling anhydritic clay rocks. One of the reasons is our limited knowledge of the processes involved in the swelling of such rocks, and of the geological, mineralogical, hydraulic, chemical and mechanical controls of the swelling. In this contribution, a review of processes in swelling anhydritic clay rocks and of associated controls is presented. Also numerical models that aim at simulating the swelling processes and controls are included in this review, and some of the remaining open questions are pointed out. By focusing on process-oriented work in this review, the presentation intends to stimulate further research across disciplines in the field of swelling anhydritic clay rocks to finally get a step further in managing the swelling problem in geotechnical engineering projects. Keywords: swelling; anhydritic clay rocks; review

  20. Orientation of FePt nanoparticles on top of a-SiO2/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size.

    PubMed

    Schilling, Martin; Ziemann, Paul; Zhang, Zaoli; Biskupek, Johannes; Kaiser, Ute; Wiedwald, Ulf

    2016-01-01

    particle orientation was found to be strongest. From a random orientation in the as-prepared state observed for both, small and large FePt NPs, annealing at 650 °C for 30 min reorients the small particles towards a cube-on-cube epitaxial orientation with a minor fraction of (111)-oriented particles. In contrast, large FePt NPs keep their as-prepared random orientation even after doubling the annealing period at 650 °C to 60 min. PMID:27335749

  1. Tool for Taking Clay Impressions

    NASA Technical Reports Server (NTRS)

    Duncan, R. S.

    1984-01-01

    Clay impression of small parts taken with tool consisting of hollow tube closed at one end. Slots at other end admit part short distance into tube. Impression used to make silicone rubber mold for examination.

  2. Prions, Radionuclides and Clays: Impact of clay interlayer "acidity" on toxic compound speciation

    NASA Astrophysics Data System (ADS)

    Charlet, L.; Hureau, C.; Sobolev, O.; Cuello, G.; Chapron, Y.

    2007-05-01

    . The speciation of the Cu-ligand complex was found to be different, in bulk water (Hureau et al., 2006) and in clay suspensions, where n increases. This new speciation of the copper metal ions, used as a molecular probe, allows to "measure" the pH of interlayer water which is shown to be significantly lower than in bulk water pH. Molecular models for PrP attachment to the clay basal plane and Sm location within the clay interlayer were obtained by MD computations. Implications on PrP pathogenicity, following carcase burial and particle ingestions, and on radionuclide mobility, following nuclear waste burial in clay rich repository sites, will be discussed.

  3. Magnetic fabric from red clay sediments in the Chinese Loess Plateau.

    PubMed

    Gong, Hujun; Zhang, Rui; Yue, Leping; Zhang, Yunxiang; Li, Jianxing

    2015-01-01

    Well-distributed eolian red clay in a wide area of northern China is believed to imply the onset of an ancient East Asian monsoon system since Late Miocene. Two continuous red clay sequences spanning the time interval 7-2.6 Ma and 11-2.6 Ma in the Chinese Loess Plateau was investigated to determine the magnetic orientation and grain alignment in the primary fabric of eolian sediments. The north-westerly orientation of the AMS of the eolian red clay sequences parallels the material transportation direction, which differs from the model that suggests that airborne dust from overlying loess-paleosol sequences were transported by the East Asian winter monsoon and fixed by the East Asian summer monsoon. Our results further reveal that present-day climate and air circulation patterns differ from those of the pre-Quaternary, and may provide evidence of a prevailing wind during deposition of the red clay. PMID:25913292

  4. Characterization of Clay Minerals and Kerogen in Alberta Oil Sands Geological End Members

    NASA Astrophysics Data System (ADS)

    Zheng, Limin

    The high degree of variability of oil sands ores can be attributed to a mixture of different geological end members, i.e., estuarine sand, estuarine clay, marine sand and marine clay. This study focused on the mineralogy, especially of clay minerals, and toluene insoluble organic matter, referred to as kerogen, in different oil sands end members. Clays and kerogens will likely have a significant impact on solvent recovery from the gangue following non-aqueous bitumen extraction. The bitumen-free solids were subjected to mineralogical and geochemical analysis. Kerogens were isolated and analyzed by various characterization methods. The types of clays were identified in oriented samples by X-ray diffraction analysis. The nitrogen to carbon ratio in the isolated kerogens is found to be higher than in bitumen. There are more type III kerogens in estuarine samples and more type II kerogens in marine samples.

  5. New magnetic organic inorganic composites based on hydrotalcite-like anionic clays for drug delivery

    NASA Astrophysics Data System (ADS)

    Carja, Gabriela; Chiriac, Horia; Lupu, Nicoleta

    2007-04-01

    The structural "memory effect" of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin-hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments.

  6. Release of surfactant cargo from interfacially-active halloysite clay nanotubes for oil spill remediation.

    PubMed

    Owoseni, Olasehinde; Nyankson, Emmanuel; Zhang, Yueheng; Adams, Samantha J; He, Jibao; McPherson, Gary L; Bose, Arijit; Gupta, Ram B; John, Vijay T

    2014-11-18

    Naturally occurring halloysite clay nanotubes are effective in stabilizing oil-in-water emulsions and can serve as interfacially-active vehicles for delivering oil spill treating agents. Halloysite nanotubes adsorb at the oil-water interface and stabilize oil-in-water emulsions that are stable for months. Cryo-scanning electron microscopy (Cryo-SEM) imaging of the oil-in-water emulsions shows that these nanotubes assemble in a side-on orientation at the oil-water interface and form networks on the interface through end-to-end linkages. For application in the treatment of marine oil spills, halloysite nanotubes were successfully loaded with surfactants and utilized as an interfacially-active vehicle for the delivery of surfactant cargo. The adsorption of surfactant molecules at the interface serves to lower the interfacial tension while the adsorption of particles provides a steric barrier to drop coalescence. Pendant drop tensiometry was used to characterize the dynamic reduction in interfacial tension resulting from the release of dioctyl sulfosuccinate sodium salt (DOSS) from halloysite nanotubes. At appropriate surfactant compositions and loadings in halloysite nanotubes, the crude oil-saline water interfacial tension is effectively lowered to levels appropriate for the dispersion of oil. This work indicates a novel concept of integrating particle stabilization of emulsions together with the release of chemical surfactants from the particles for the development of an alternative, cheaper, and environmentally-benign technology for oil spill remediation. PMID:25346266

  7. Polyimide-Clay Composite Materials for Space Application

    NASA Technical Reports Server (NTRS)

    Orwoll, Robert A.; Connell, John W. (Technical Monitor)

    2005-01-01

    The introduction of nanometer-sized clay particles into a polyimide matrix has been shown to enhance the physical properties of specific polymer systems. The clay comprises large stacked platelets of the oxides of aluminum and silicon. These sheets have long dimensions on the order of tenths of a micrometer and thicknesses of several nanometers. Homogeneous dispersion of the clay platelets in the polymer matrix is necessary to achieve those enhancements in polymer properties. Natural montmorillonite with the empirical formula Na0.33Mg0.33Al1.67(OH)2(Si4O10) contains exchangeable inorganic cations. The clay lamellae stack together with the positive sodium ions situated between the surfaces of the individual sheets to balance negatively charged oxygen atoms that are on the surfaces of the sheets. These surface charges contribute to strong electrostatic forces which hold the sheets together tightly. Exfoliation can be accomplished only with unusual measures. In preparing clay nanocomposites, we have taken two steps to try to reduce these interlamellar forces in order to promote the separation (exfoliation) of the sheets and the dispersion of the individual clay particles throughout the organic polymer matrix. In the first step, some of the surface Na(+) ions are replaced with Li(+) ions. Unlike sodium cations, the lithium cations migrate into the interior of the lamellae when the system is heated. Their departure from the surface reduces the surface charge and therefore the attractive forces between the sheets. The loss of alkali metal cations from the surface can be measured as the cation exchange capacity (CEC) of the clay. For example, we found that the CEC of montmorillonite clay was reduced by almost two thirds by treating it with lithium ions and heating to 250 C for 24 hr. Lesser heating has a smaller effect on the CEC. X-ray diffraction measurements show that the d-spacing decreased from ca. 1.34 to 0.97 nm, apparently a consequence of a collapse of the clay

  8. Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility

    NASA Astrophysics Data System (ADS)

    Ambers, R. K.; Stine, M. B.

    2005-12-01

    Soil scientists concerned with erosion of agricultural fields and geotechnical engineers concerned with the mechanical behavior of soils under different conditions have both examined the role of clay mineralogy in controlling soil/sediment properties. Fluvial geomorphologists studying stream channel erosion and stability have focused more on the effects of particle-size distribution, vegetation and rooting. The clay mineralogy of bed and bank sediment has the potential to influence cohesiveness and erodibility, however. The goal of this study is to determine the influence of clay mineralogy on the erodibility of natural stream bank sediment, utilizing techniques drawn from pedology and soil mechanics. Bank samples were collected from eleven sites in small watersheds in central and western Virginia. To obtain sediment containing a range of different clay minerals, watersheds with different types of bedrock were chosen for sampling. Rock types included mafic to felsic metamorphic and igneous rocks, shale, sandstone, and limestone. Where stream bank materials were clearly stratified, different layers were sampled separately. X-ray diffraction of the clay-fraction of the sediment indicates the presence of kaolinite, illite, vermiculite, and mixed-layer clay minerals in various abundances in the different samples. Clay content is 9-46%, as determined by the hydrometer method, and textures range from silty clay and silt loam to clay loam and sandy loam. Organic mater contents range from 1-5% by the loss-on-ignition method. Bulk density of intact sediment samples averages 1.5 g/cc. Liquid limits range from 23-41 with one sample having a value of 65; plasticity indices range from 15-22. While these tests predict that the samples would show a range of mechanical behaviors, the channel morphology at the sampling sites was not strikingly different, all having steep cut banks eroded primarily by scour with no evidence of mass movement and most having a width/depth ratio around

  9. Potential bioavailability of mercury in humus-coated clay minerals.

    PubMed

    Zhu, Daiwen; Zhong, Huan

    2015-10-01

    It is well-known that both clay and organic matter in soils play a key role in mercury biogeochemistry, while their combined effect is less studied. In this study, kaolinite, vermiculite, and montmorillonite were coated or not with humus, and spiked with inorganic mercury (IHg) or methylmercury (MeHg). The potential bioavailability of mercury to plants or deposit-feeders was assessed by CaCl2 or bovine serum albumin (BSA) extraction. For uncoated clay, IHg or MeHg extraction was generally lower in montmorillonite, due to its greater number of functional groups. Humus coating increased partitioning of IHg (0.5%-13.7%) and MeHg (0.8%-52.9%) in clay, because clay-sorbed humus provided more strong binding sites for mercury. Furthermore, humus coating led to a decrease in IHg (3.0%-59.8% for CaCl2 and 2.1%-5.0% for BSA) and MeHg (8.9%-74.6% for CaCl2 and 0.5%-8.2% for BSA) extraction, due to strong binding between mercury and clay-sorbed humus. Among various humus-coated clay particles, mercury extraction by CaCl2 (mainly through cation exchange) was lowest in humus-coated vermiculite, explained by the strong binding between humus and vermiculite. The inhibitory effect of humus on mercury bioavailability was also evidenced by the negative relationship between mercury extraction by CaCl2 and mercury in the organo-complexed fraction. In contrast, extraction of mercury by BSA (principally through complexation) was lowest in humus-coated montmorillonite. This was because BSA itself could be extensively sorbed onto montmorillonite. Results suggested that humus-coated clay could substantially decrease the potential bioavailability of mercury in soils, which should be considered when assessing risk in mercury-contaminated soils. PMID:26456605

  10. Biodegradable pectin/clay aerogels.

    PubMed

    Chen, Hong-Bing; Chiou, Bor-Sen; Wang, Yu-Zhong; Schiraldi, David A

    2013-03-13

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. The addition of multivalent cations (Ca(2+) and Al(3+)) resulted in apparent cross-linking of the polymer and enhancement of aerogel properties. The compressive properties increased as the solid contents (both pectin and clay) increased; moduli in the range of 0.04-114 MPa were obtained for materials with bulk densities ranging from 0.03 g/cm(3) to 0.19 g/cm(3), accompanied by microstructural changes from a lamellar structure to a cellular structure. Biodegradability of the aerogels was investigated by detecting CO2 release for 4 weeks in compost media. The results revealed that pectin aerogels possess higher biodegradation rates than wheat starch, which is often used as a standard for effective biodegradation. The addition of clay and multivalent cations surprisingly increased the biodegradation rates. PMID:23406325

  11. Boron Enrichment in Martian Clay

    PubMed Central

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  12. Boron enrichment in martian clay.

    PubMed

    Stephenson, James D; Hallis, Lydia J; Nagashima, Kazuhide; Freeland, Stephen J

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  13. Clay Mineralogy: The clay mineral composition of soils and clays is providing an understanding of their properties.

    PubMed

    Grim, R E

    1962-03-16

    The structures of the clay minerals are reasonably well known, but greater detail and more precision are needed if the properties of clays and soils are to be fully understood. For example, the selective adsorptive and catalytic properties and the reaction with organic materials vary with the character of the clay mineral, but the structural factors that control such properties are not well understood. Research is urgently needed on the structure of pure clay minerals and on the reactions of pure clay minerals with organic and inorganic materials. Much past research on clay-mineral reactions has little fundamental value because the clay that was used was composed of a mixture of minerals which were not well characterized. It is not a simple matter to find pure samples of many of the clay minerals, and to a considerable extent progress depends on finding such pure minerals or preparing them in the laboratory. PMID:17816101

  14. A Novel Prime and Boost Regimen of HIV Virus-Like Particles with TLR4 Adjuvant MPLA Induces Th1 Oriented Immune Responses against HIV.

    PubMed

    Poteet, Ethan; Lewis, Phoebe; Li, Feng; Zhang, Sheng; Gu, Jianhua; Chen, Changyi; Ho, Sam On; Do, Thai; Chiang, SuMing; Fujii, Gary; Yao, Qizhi

    2015-01-01

    HIV virus-like particles (VLPs) present the HIV envelope protein in its native conformation, providing an ideal vaccine antigen. To enhance the immunogenicity of the VLP vaccine, we sought to improve upon two components; the route of administration and the additional adjuvant. Using HIV VLPs, we evaluated sub-cheek as a novel route of vaccine administration when combined with other conventional routes of immunization. Of five combinations of distinct prime and boost sequences, which included sub-cheek, intranasal, and intradermal routes of administration, intranasal prime and sub-cheek boost (IN+SC) resulted in the highest HIV-specific IgG titers among the groups tested. Using the IN+SC regimen we tested the adjuvant VesiVax Conjugatable Adjuvant Lipid Vesicles (CALV) + monophosphoryl lipid A (MPLA) at MPLA concentrations of 0, 7.5, 12.5, and 25 μg/dose in combination with our VLPs. Mice that received 12.5 or 25 μg/dose MPLA had the highest concentrations of Env-specific IgG2c (20.7 and 18.4 μg/ml respectively), which represents a Th1 type of immune response in C57BL/6 mice. This was in sharp contrast to mice which received 0 or 7.5 μg MPLA adjuvant (6.05 and 5.68 μg/ml of IgG2c respectively). In contrast to IgG2c, MPLA had minor effects on Env-specific IgG1; therefore, 12.5 and 25 μg/dose of MPLA induced the optimal IgG1/IgG2c ratio of 1.3. Additionally, the percentage of germinal center B cells increased significantly from 15.4% in the control group to 31.9% in the CALV + 25 μg MPLA group. These mice also had significantly more IL-2 and less IL-4 Env-specific CD8+ T cells than controls, correlating with an increased percentage of Env-specific central memory CD4+ and CD8+ T cells. Our study shows the strong potential of IN+SC as an efficacious route of administration and the effectiveness of VLPs combined with MPLA adjuvant to induce Env specific Th1-oriented HIV-specific immune responses. PMID:26312747

  15. Crystal chemistry and Mössbauer spectroscopic analysis of clays around Riyadh for brick industry

    NASA Astrophysics Data System (ADS)

    Khalil, Mutasim I.

    2013-04-01

    A total of 30 clay samples were collected from the area around Riyadh city, Saudi Arabia. A complete chemical analysis was carried out using different techniques. X-ray diffraction studies showed that the clay samples were mainly of the smectite group with traces of the kaolinite one. The samples studied were classified as nontronite clay minerals. One of the clay fraction has been studied by Mössbauer spectroscopy as raw clay fraction and after being fired at 950-1,000 °C. The Mössbauer spectra showed accessory iron compounds in the form of hematite and goethite. The structural iron contents disintegrate on firing transforming into magnetic iron oxide and a paramagnetic small particles iron oxide.

  16. Rheological properties of purified illite clays in glycerol/water suspensions

    NASA Astrophysics Data System (ADS)

    Dusenkova, I.; Malers, J.; Berzina-Cimdina, L.

    2015-04-01

    There are many studies about rheological properties of clay-water suspensions, but no published investigations about clay-glycerol suspensions. In this work apparent viscosity of previously purified illite containing clay fraction < 2 μm and glycerol/water suspensions were investigated. Carbonates were removed by dissolution in hydrochloric and citric acids and other non-clay minerals were almost totally removed by centrifugation. All obtained suspensions behaved as shear-thinning fluids with multiple times higher viscosity than pure glycerol/water solutions. Reduction of clay fraction concentration by 5% decreased the apparent viscosity of 50% glycerol/water suspensions approximately 5 times. There was basically no difference in apparent viscosity between all four 50% glycerol/water suspensions, but in 90% glycerol/water suspensions samples from Iecava deposit showed slightly higher apparent viscosity, which could be affected by the particle size distribution.

  17. Radiation-induced defects in clay minerals: A review

    NASA Astrophysics Data System (ADS)

    Allard, Th.; Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S.

    2012-04-01

    Extensive information has been collected on radiation effects on clay minerals over the last 35 years, providing a wealth of information on environmental and geological processes. The fields of applications include the reconstruction of past radioelement migrations, the dating of clay minerals or the evolution of the physico-chemical properties under irradiation. The investigation of several clay minerals, namely kaolinite, dickite, montmorillonite, illite and sudoite, by Electron Paramagnetic Resonance Spectroscopy has shown the presence of defects produced by natural or artificial radiations. These defects consist mostly of electron holes located on oxygen atoms of the structure. The various radiation-induced defects are differentiated through their nature and their thermal stability. Most of them are associated with a π orbital on a Si-O bond. The most abundant defect in clay minerals is oriented perpendicular to the silicate layer. Thermal annealing indicates this defect in kaolinite (A-center) to be stable over geological periods at ambient temperature. Besides, electron or heavy ion irradiation easily leads to an amorphization in smectites, depending on the type of interlayer cation. The amorphization dose exhibits a bell-shaped variation as a function of temperature, with a decreasing part that indicates the influence of thermal dehydroxylation. Two main applications of the knowledge of radiation-induced defects in clay minerals are derived: (i) The use of defects as tracers of past radioactivity. In geological systems where the age of the clay can be constrained, ancient migrations of radioelements can be reconstructed in natural analogues of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to fault gouges or laterites of the Amazon basin. (ii) The influence of irradiation over physico-chemical properties of clay minerals. An environmental

  18. [Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

    PubMed

    Zhang, Zhi-Dan; Luo, Xiang-Li; Jiang, Hai-Chao; Li, Qiao; Shen, Cong-Ying; Liu, Hang; Zhou, Ya-Juan; Zhao, Lan-Po; Wang, Ji-Hong

    2014-07-01

    The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study. PMID:25269317

  19. Picasso Masks: Cubism in Clay

    ERIC Educational Resources Information Center

    Daddino, Michelle

    2010-01-01

    This article describes an art project developed by the author which provides a way to further the children's understanding of Picasso's Cubism style in 3-D. Through this project, upper-elementary students learn a bit about the life and art of Picasso as they gain a firm understanding of the style of art known as Cubism, and apply clay techniques…

  20. Biodegradable Pectin/clay Aerogels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  1. Amitriptyline removal using palygorskite clay.

    PubMed

    Tsai, Yo-Lin; Chang, Po-Hsiang; Gao, Zong-You; Xu, Xiao-Yuan; Chen, Yan-Hsin; Wang, Zheng-Hong; Chen, Xin-Yu; Yang, Zheng-Ying; Wang, Tzu-Hao; Jean, Jiin-Shuh; Li, Zhaohui; Jiang, Wei-Teh

    2016-07-01

    With the increased detections of commonly used pharmaceuticals in surface water and wastewater, extensive attentions were paid recently to the fate and transport of these pharmaceuticals in the environment. Amitriptyline (AMI) is a tricyclic antidepressant widely applied to treat patients with anxiety and depression. In this study, the removal of AMI with palygorskite clay (PFl-1) was investigated under different physico-chemical conditions and supplemented by instrumental analyses. The uptake of AMI on PFl-1 was well fitted by the Langmuir isotherm with an adsorption capacity of 0.168 mmol g(-1) at pH 6-7. The AMI uptake was fast and reached equilibrium in 15 min. The X-ray diffraction patterns showed no shift of the (110) peak position of palygorskite after AMI uptake. However, the (001) peak position of the minor component smectite (about 10%) shifted to lower angle as the amounts of AMI input increased. These results suggested surface uptake of AMI on palygorskite and interlayer uptake of AMI in smectite. As smectite is a common component of palygorskite clays, its role in assessing the properties and performances of palygorskite clays for the uptake and removal of contaminants should not be neglected. Overall, the high affinity of AMI for PFl-1 and strong retention of AMI on PFl-1 suggested that it could be a good adsorbent to remove AMI from wastewater. Palygorskite clays can also be a sink for many cationic pharmaceuticals in the environmental of the arid regions. PMID:27131449

  2. ADSORPTION OF SURFACTANT ON CLAYS

    EPA Science Inventory

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  3. Stools - pale or clay-colored

    MedlinePlus

    ... gov/ency/article/003129.htm Stools - pale or clay-colored To use the sharing features on this page, please enable JavaScript. Stools that are pale, clay, or putty-colored may be due to problems ...

  4. Multifunctional epoxy composites with natural Moroccan clays

    NASA Astrophysics Data System (ADS)

    Monsif, M.; Zerouale, A.; Kandri, N. Idrissi; Allali, F.; Sgarbossa, P.; Bartolozzi, A.; Tamburini, S.; Bertani, R.

    2016-05-01

    Two natural Moroccan clays, here firstly completely characterized, have been used as fillers without modification in epoxy composites. Mechanical properties resulted to be improved and a significant antibacterial activity is exhibited by the epoxy composite containing the C2 clay.

  5. Adsorption of RDX on clay

    NASA Astrophysics Data System (ADS)

    Colon, Yleana M.; Alzate, Liliana F.; Ramos, Carmen M.; Santana, Alberto; Hernandez-Rivera, Samuel P.; Castro, Miguel E.; Munoz, Miguel; Mina, Nairmen

    2004-09-01

    The chemical spectroscopic signature of the RDX-clay mineral complex has been investigated by means of reflectance FT-IR micro spectroscopy. The mechanical analysis method was used to separate the clay from the other soil components. The soil was obtained from the University of Puerto Rico at Mayag'ez (UPRM) campus backyard. B3LYP/6-311G** calculations performed on RDX helped to determine the most stable conformations, their symmetry, and vibrational spectra. The FTIR technique confirmed the existence of two different RDX solid phases, known as the α-RDX and β-RDX, which have different symmetries and revealed significant differences in their spectra. The IR microspectroscopic study showed that the RDX-clay mineral complex and its interactions can be detected using the FTIR technique at a low concentration of 1000 part-per-millions. The results also suggest that the vibrational modes presenting changes in the different vibrational spectra correspond to the C-N and NO2 groups. In comparison with α-RDX spectrum, the complex exhibits three bands at 740, 754 and 792 cm-1. A 12 cm-1 red shift is observed in this last band assign to the C-N stretching and NO2 scissoring vibrations in the equatorial position. Differences in the spectra were also seen in the shifted bands at 942 and 953 cm-1. These vibrational modes are assigned to the ring breathing and N-N stretching vibration in the axial position for the -phase. Comparison of the spectra of the α-RDX, the β-RDX and the RDX mixed with clay in the range from 1190 to 1700 cm-1 clearly indicated that the FTIR technique can be used to study the interaction between RDX and clay. The results also indicate that the interaction between the RDX and the clay minerals affects mainly the NO2 groups of the explosive molecules. It is suggested that the electron donor nitrogen atoms from RDX are interacting with the electron acceptor oxygen atoms of the siloxane surface that is present in the majority of clays.

  6. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  7. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and....1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain varying quantities of alkalies...

  8. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  9. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  10. Mineral resource of the month: clays

    USGS Publications Warehouse

    Virta, Robert

    2004-01-01

    Clays represent one of the largest mineral commodities in the world in terms of mineral and rock production and use. Many people, however, do not recognize that clays are used in an amazingly wide variety of applications. Use continues to increase worldwide as populations and their associated needs increase. Robert Virta, clay and shale commodity specialist for the U.S. Geological Survey, has prepared the following information about clays.

  11. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  12. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-0866 Varma*, R.S. Clay and Clay-Supported Reagents in Organic Syntheses. Tetrahedron (Sir J.E. Baldwin (Ed.), Elsevier Science Ltd) 58 (7):1235-1255 (2002). EPA/600/J-02/032. 10/28/1999 CLAY AND CLAY-SUPPORTED REAGENTS HAVE BEEN USED EXTENSIVELY FOR SYNTHETIC ORGA...

  13. Electrokinetics of natural and mechanically modified ripidolite and beidellite clays

    SciTech Connect

    Sondi, I.; Pravdic, V.

    1996-08-10

    Particles of clay minerals were studied due to their importance in geochemical processes in natural waters, such as adsorption and transfer of ionic contaminants, stabilization by organics, and flocculation and sedimentation phenomena. Information on the behavior of clays was sought by experiments with model systems. Measurements of electrophoretic mobilities in relation to pH, at varying concentrations of well-characterized fulvic acid (FA), were performed on two structurally well defined, representative clay minerals prepared with clean surfaces: ripidolite (a well-known trioctahedral nonswelling chlorite) and beidellite (a typical dioctahedral smectite). Natural ripidolite and beidellite show high negative electrokinetic potentials in the range pH 2 ({minus}10 and {minus}20 mV, respectively) to pH 10 ({minus}60 and {minus}50 mV, respectively). Experiments utilizing mechanical particle disintegration (dry milling), mimicking natural wear and physical weathering, resulted in increases of specific surface area (12.3 and 1.5 times, respectively) and of cation exchange capacity (3.2 and 1.2 times, respectively). Such small-sized particles, shown by SEM figures, retain their crystal structure (X ray) and the nature of their structural bonds (FTIR), exhibiting an IEP (at pH 6.0 and 3.0, respectively). This was interpreted to be the creation of positively charged edge surfaces. Exposed to fulvic acid in solutions of 10{sup {minus}3} NaCl at pH = 6.5, these new surfaces showed an increase in negative {zeta}-potential for ripidolite, and, to a smaller extent, for beidellite. In the interaction of clay mineral particles with aqueous medium, it is concluded that the degree of mechanical wear is more decisive than the type of the mineral.

  14. Clay & Children: More than Making Pots.

    ERIC Educational Resources Information Center

    Kolbe, Ursula

    1997-01-01

    Working with clay enables young children to express, explore, and communicate their feelings and ideas. This resource booklet for early childhood practitioners and it promotes the clay table as a special place for shared discoveries, social interaction, and discussion. The booklet provides a glossary of terms used in clay work, as well as reasons…

  15. GEOSYNTHETIC CLAY LINERS (GCLS) IN LANDFILL COVERS

    EPA Science Inventory

    Low permeability, compacted clay linters are commonly required as a barrier to water infiltration in landfill covers. elatively new material, known as geosynthetic clay liner (GCL), has been proposed as an alternative to a compacted clay liner. CL has the practical advantages of ...

  16. Clay Cuffman: A Cool, Calm, Relaxed Guy

    ERIC Educational Resources Information Center

    Booth, Gina

    2010-01-01

    This article describes Clay Cuffman, a simple clay-sculpture project that requires two or three sessions, and works for students from the upper-elementary level through high school. It takes about 1.5 pounds of clay per student--about the size of a small grapefruit. The Cuffman project is a great way for upper-elementary through high-school…

  17. Brownian dynamics simulation of orientational behavior, flow-induced structure, and rheological properties of a suspension of oblate spheroid particles under simple shear

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takehiro; Suga, Takanori; Mori, Noriyasu

    2005-08-01

    Brownian dynamics (BD) simulations were carried out for suspensions of oblate spheroid particles interacting via the Gay-Berne (GB) potential. The oblate spheroid particles were applied as a model of disc-like particles and the system of suspension of the particles was considered. Numerically analyzed were both the change in phase with the number density of the particles at equilibrium state and the behavior of the particles in simple shear flows. The system changed from isotropic phase to nematic one with increasing the particle concentration. In the simulation of shear flows, the shear was imposed upon the systems in nematic phase at equilibrium. The systems exhibited various motions of the director depending on the shear rate, e.g. the continuous rotation of director at low shear rates, the wagging at moderate shear rates, and the flow aligning at high shear rates. Temporal change in inner structure of suspensions was also analyzed and collapse of initial particle configurations due to shear was found. Moreover, rheological properties of the suspension were investigated. The numerical simulation predicted the shear-thinning in viscosity, negative first normal stress difference, and positive second normal stress difference, and these results qualitatively agreed with the predictions using a constitutive equation for discotic nematics. The present study proved that the BD simulation using spheroid particles interacting via the GB potential is an effective approach for investigating the flow behavior and flow-induced structure of suspensions of disklike particles at a particulate level.

  18. Brownian dynamics simulation of orientational behavior, flow-induced structure, and rheological properties of a suspension of oblate spheroid particles under simple shear.

    PubMed

    Yamamoto, Takehiro; Suga, Takanori; Mori, Noriyasu

    2005-08-01

    Brownian dynamics (BD) simulations were carried out for suspensions of oblate spheroid particles interacting via the Gay-Berne (GB) potential. The oblate spheroid particles were applied as a model of disc-like particles and the system of suspension of the particles was considered. Numerically analyzed were both the change in phase with the number density of the particles at equilibrium state and the behavior of the particles in simple shear flows. The system changed from isotropic phase to nematic one with increasing the particle concentration. In the simulation of shear flows, the shear was imposed upon the systems in nematic phase at equilibrium. The systems exhibited various motions of the director depending on the shear rate, e.g. the continuous rotation of director at low shear rates, the wagging at moderate shear rates, and the flow aligning at high shear rates. Temporal change in inner structure of suspensions was also analyzed and collapse of initial particle configurations due to shear was found. Moreover, rheological properties of the suspension were investigated. The numerical simulation predicted the shear-thinning in viscosity, negative first normal stress difference, and positive second normal stress difference, and these results qualitatively agreed with the predictions using a constitutive equation for discotic nematics. The present study proved that the BD simulation using spheroid particles interacting via the GB potential is an effective approach for investigating the flow behavior and flow-induced structure of suspensions of disklike particles at a particulate level. PMID:16196575

  19. Recycling of sugarcane bagasse ash waste in the production of clay bricks.

    PubMed

    Faria, K C P; Gurgel, R F; Holanda, J N F

    2012-06-30

    This work investigates the recycling of sugarcane bagasse ash waste as a method to provide raw material for clay brick bodies, through replacement of natural clay by up 20 wt.%. Initially, the waste sample was characterized by its chemical composition, X-ray diffraction, differential thermal analysis, particle size, morphology and pollution potential. Clay bricks pieces were prepared, and then tested, so as to determine their technological properties (e.g., linear shrinkage, water absorption, apparent density, and tensile strength). The sintered microstructure was evaluated by scanning electron microscopy (SEM). It was found that the sugarcane bagasse ash waste is mainly composed by crystalline silica particles. The test results indicate that the sugarcane bagasse ash waste could be used as a filler in clay bricks, thus enhancing the possibility of its reuse in a safe and sustainable way. PMID:22387325

  20. Effects of clay dispersion on aquifer storage and recovery in coastal aquifers

    USGS Publications Warehouse

    Konikow, L.F.; August, L.L.; Voss, C.I.

    2001-01-01

    Cyclic injection, storage, and withdrawal of freshwater in brackish aquifers is a form of aquifer storage and recovery (ASR) that can beneficially supplement water supplies in coastal areas. A 1970s field experiment in Norfolk, Virginia, showed that clay dispersion in the unconsolidated sedimentary aquifer occurred because of cation exchange on clay minerals as freshwater displaced brackish formation water. Migration of interstitial clay particles clogged pores, reduced permeability, and decreased recovery efficiency, but a calcium preflush was found to reduce clay dispersion and lead to a higher recovery efficiency. Column experiments were performed in this study to quantify the relations between permeability changes and clay mineralogy, clay content, and initial water salinity. The results of these experiments indicate that dispersion of montmorillonite clay is a primary contributor to formation damage. The reduction in permeability by clay dispersion may be expressed as a linear function of chloride content. Incorporating these simple functions into a radial, cross-sectional, variable-density, ground-water flow and transport model yielded a satisfactory simulation of the Norfolk field test - and represented an improvement over the model that ignored changes in permeability. This type of model offers a useful planning and design tool for ASR operations in coastal clastic aquifer systems.

  1. Clay flocculation improved by cationic poly(vinyl alcohol)/anionic polymer dual-component system.

    PubMed

    Sang, Yizhou; Xiao, Huining

    2008-10-15

    The synthesis of cationically modified poly(vinyl alcohol), CPVA, by copolymerization of vinyl acetate and diallyldimethyl ammonium chloride (DADMAC), followed by alkaline hydrolysis was systematically studied. The application of the resulting polymer to the fine clay flocculation was also reported. The charge density and the structure of the resulting CPVA were characterized by polyelectrolyte titration and NMR. A photometric dispersion analyzer was used to conduct the dynamic flocculation experiments. Under fine clay experimental conditions, the CPVA alone contributed little to inducing clay flocculation. However, in conjunction with anionic polyacrylamide-based polymer with high molecular weight and low charge density, significant improvement in the flocculation of fine clay particles was achieved. The influence of factors such as pH and shear force on clay flocculation was also investigated to identify optimum application conditions for clay flocculation. The electrostatic interactions between the clay and CPVA, as well as those between the CPVA pre-treated clay and anionic polymer, were studied to explore the flocculation mechanism. PMID:18657822

  2. Evaluation of the healing activity of therapeutic clay in rat skin wounds.

    PubMed

    Dário, Giordana Maciel; da Silva, Geovana Gomes; Gonçalves, Davi Ludvig; Silveira, Paulo; Junior, Adilson Teixeira; Angioletto, Elidio; Bernardin, Adriano Michael

    2014-10-01

    The use of clays for therapeutic practice is widespread in almost all regions of the world. In this study the physicochemical and microbiological healing characteristics of a clay from Ocara, Brazil, popularly used for therapeutic uses, were analyzed. The presence of Ca, Mg, Al, Fe, and Si was observed, which initially indicated that the clay had potential for therapeutic use. The average particle size of the clay (26.3 μm) can induce the microcirculation of the skin and the XRD analysis shows that the clay is formed by kaolinite and illite, a swelling clay. During the microbiological evaluation there was the need to sterilize the clay for later incorporation into the pharmaceutical formula. The accelerated stability test at 50°C for 3 months has showed that the pharmaceutical formula remained stable with a shelf life of two years. After the stability test the wound-healing capacity of the formulation in rats was evaluated. It was observed that the treatment made with the formulation containing the Ocara clay showed the best results since the formula allowed greater formation of collagen fibers and consequent regeneration of the deep dermis after seven days of treatment and reepithelialization and continuous formation of granulation tissue at the 14th day. PMID:25175195

  3. Orientation of FePt nanoparticles on top of a-SiO2/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size

    PubMed Central

    Schilling, Martin; Ziemann, Paul; Zhang, Zaoli; Biskupek, Johannes; Kaiser, Ute

    2016-01-01

    effect of annealing on particle orientation was found to be strongest. From a random orientation in the as-prepared state observed for both, small and large FePt NPs, annealing at 650 °C for 30 min reorients the small particles towards a cube-on-cube epitaxial orientation with a minor fraction of (111)-oriented particles. In contrast, large FePt NPs keep their as-prepared random orientation even after doubling the annealing period at 650 °C to 60 min. PMID:27335749

  4. The Use of Clay-Polymer Nanocomposites in Wastewater Pretreatment

    PubMed Central

    Rytwo, Giora

    2012-01-01

    Some agricultural effluents are unsuitable for discharge into standard sewage-treatment plants: their pretreatment is necessary to avoid clogging of the filtering devices by colloidal matter. The colloidal stability of the effluents is mainly due to mutual repulsive forces that keep charged particles in suspension. Pretreatment processes are based on two separate stages: (a) neutralization of the charges (“coagulation”) and (b) bridging between several small particles to form larger aggregates that sink, leaving clarified effluent (“flocculation”). The consequent destabilization of the colloidal suspension lowers total suspended solids (TSSs), turbidity, and other environmental quality parameters, making the treatments that follow more efficient. Clay-based materials have been widely used for effluent pretreatment and pollutant removal. This study presents the use of nanocomposites, comprised of an anchoring particle and a polymer, as “coagoflocculants” for the efficient and rapid reduction of TSS and turbidity in wastewater with a high organic load. The use of such particles combines the advantages of coagulant and flocculant by neutralizing the charge of the suspended particles while bridging between them and anchoring them to a denser particle (the clay mineral), enhancing their precipitation. Very rapid and efficient pretreatment is achieved in one single treatment step. PMID:22454607

  5. Mathematical modeling of bacteria and clay co-transport in porous media

    NASA Astrophysics Data System (ADS)

    Vasiliadou, Ioanna A.; Chrysikopoulos, Constantinos V.

    2010-05-01

    The present study focuses on Pseudomonas putida bacteria transport in porous media in the presence of suspended kaolinite clay particles. Experiments were performed with bacteria and kaolinite particles separately to determine their individual transport characteristics in water saturated columns packed with glass beads. The results indicate that the mass recovery of bacteria and clay particles decreased as the pore water velocity decreased. Batch experiments were carried out to investigate the adsorption of Pseudomonas putida onto kaolinite particles. The adsorption process is adequately described by a Langmuir isotherm. Finally, bacteria and kaolinite particles were injected simultaneously into a packed column in order to investigate their co-transport behavior. The experimental data suggest that the presence of clay particles significantly inhibit the transport of bacteria in water saturated porous media. The observed reduction of Pseudomonas putida recovery at the column exit is attributed to bacteria attachment onto kaolinite particles, which are retained onto the solid matrix of the column. A mathematical model was developed to describe the transport of bacteria in the presence of suspended clay particles in one-dimensional water saturated porous media. Model simulations are in good agreement with the experimental results.

  6. ESEM study of the humidity-induced swelling of clay film.

    PubMed

    Carrier, Benoit; Wang, Linlin; Vandamme, Matthieu; Pellenq, Roland J-M; Bornert, Michel; Tanguy, Alexandre; Van Damme, Henri

    2013-10-15

    We measured the humidity-induced swelling of thin self-standing films of montmorillonite clay by a combination of environmental scanning electron microscopy (ESEM) and digital image correlation (DIC). The films were about 40 μm thick. They were prepared by depositing and evaporating a suspension of clay and peeling off the highly oriented deposits. The rationale for creating such original samples was to obtain mesoscopic samples that could be used to bridge experimentally the gap between the scale of the clay layer and the engineering scale of a macroscopic clay sample. Several montmorillonite samples were used: the reference clay Swy-2, the same clay homoionized with sodium or calcium ions, and a sodium-exchanged Cloisite. The edges of the clay films were observed by ESEM at various relative humidity values between 14% and 95%. The ESEM images were then analyzed by DIC to measure the swelling or the shrinkage of the films. We also measured the adsorption/desorption isotherms by weighing the film samples in a humidity-controlled environment. In order to analyze our results, we compared our swelling/shrinkage and adsorption/desorption data with previously published data on the interlayer spacing obtained by X-ray diffraction and with numerical estimates of the interlayer water obtained by molecular dynamics simulation. The swelling and the hysteresis of this swelling were found to be comparable for the overall macroscopic films and for the interlayer space. The same correspondence between film and interlayer space was observed for the amount of adsorbed water. This suggests that, in the range of relative humidities values explored, the films behave like freely swelling oriented stacks of clay layers, without any significant contribution from the mesoporosity. The relevance of this result for the behavior of clayey sedimentary rocks and the differences with the behavior of nonoriented samples (powders or compacted powders) are briefly discussed. PMID:24044513

  7. Fundamental investigations of clay/polymer nanocomposites and applications in co-extruded microlayered systems

    NASA Astrophysics Data System (ADS)

    Decker, Jeremy John

    The second and fourth generations of hydroxylated dendritic polyesters (HBP2, HBP4) were combined with unmodified sodium montmorillonite clay (Na +MMT) in water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacings were independent of generation number and changed over the composition range from 0.5 nm to 3.5 nm in 0.5 nm increments that corresponded to a flattened HBP conformation within the clay tactoids. The HBP4/Na+MMT systems were investigated to study the vitrified Rigid Amorphous Fraction (RAF) induced by the clay surfaces. Differential Scanning Calorimetry (DSC) showed changes in heat capacity, Delta Cp, at Tg, that decreased with clay content, until completely suppressed at 80 wt% Na+MMT due to confinement. RAF was quantified from these changes in heat capacity and verified by the analysis of orthopositronium lifetime temperature scans utilizing positron annihilation lifetime spectroscopy (PALS): verifying the glassy nature of the RAF at elevated temperatures. Mathematical relationships allowed for correlation of the interlayer spacings with DeltaC p. RAF formation correlated to intercalated HBP4, and external surfaces of the clay tactoids. The interdiffusion of a polymer pair in microlayers was exploited to increase the concentration of nanoclay particles. When microlayers of a nanocomposite composed of organically modified montmorillonite (M2(HT)2 ) inside maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MA) and low-density polyethylene (LDPE) were taken into the melt, the greater mobility of the linear LLDPE-g-MA chains compared to the branched LDPE chains caused shrinkage of the nanocomposite microlayers, concentrating the M 2(HT)2 contained within. Analysis of the clay morphology within these layers demonstrated an increase in clay

  8. Modernity and putty-clay

    NASA Astrophysics Data System (ADS)

    Ganesh, Trichur Kailas

    This dissertation addresses issues arising out of the problems of capital accumulation, productivity growth and 'putty-clay' technology. The concept of economic modernity occupies a central place in the subject-matter studied here in that it expresses both the incessant drive for newness that characterizes economic reality and the persistence of dated techniques that successfully resist replacement. This study examines the way in which an expansive development-theoretic 'putty-clay' framework may be employed to explain the historical processes behind both the avalanche of newness (innovations) and the conservatism of technology in the U.S. economy. The guiding link is the fixity of investments in physical capital equipment over time and space. The dilemma of fixed capital is studied in the context of the constant entrepreneurial search for flexibility and liquidity. The thesis advanced is that a development (Entwicklung)-theoretic 'putty-clay' conceptualization of the economic system adequately addresses the recurring problems of fixity, flexibility, and liquidity, and thereby permits important insights into the enigma surrounding the persistent productivity growth slowdown and 'stagflation' of the late sixties and seventies and the related phenomena of physical 'capital obsolescence' and the financial or 'speculative explosions' of our times. The notion of 'putty-clay' used here is an innovative one in that it departs from the growth-theoretic literature to re-appear as a Schumpeterian theory of modernity modified by a Veblenite view of an economic system directed by the exigencies of the 'machine-process'. The empirical aptitude of a macroeconomic 'putty-clay' model to explain capital obsolescence mediated by the energy 'crises' (supply shocks) of the seventies and eighties is examined in a separate chapter with results that differ markedly from the standard (Berndt and Wood) conclusions for the U.S. economy. The final chapter in the dissertation reverts to the

  9. Effect of iron diagenesis on the transport of colloidal clay in an unconfined sand aquifer

    SciTech Connect

    Ryan, J.N.; Gschwend, P.M. )

    1992-04-01

    The role of Fe diagenesis in the transport of clay colloids was investigated in the Cohansey Sand, an Fe(III) oxide-coated quartz arenite that covers most of the New Jersey Coastal Plain. Based on the authors' past work, they hypothesized that clay had been transported into the sediments, that the clay distribution was controlled by attachment to surface Fe(III) oxides, and that anoxic water infiltrating from a swamp had dissolved Fe(III) oxides and released clay colloids into flowing groundwater. Sediment cores were collected from upland and swamp terrains, and the composition and distribution of the clay-sized and heavy mineral fractions were examined by X-ray diffraction, optical and electron microscopy, separations, and elemental analyses. The clay-sized content of the oxidized sediments was roughly double that of the reduced sediments. Electron microscopy revealed that coatings on the quartz grains had the appearance of infiltrated clay particles. The relationship between clay and surface Fe content indicated that the onset of reducing conditions below the swamp remobilized clay colloids by dissolving Fe(III) oxide cement. Surface Fe(III) oxides were derived from weathering of ilmenite and pseudorutile, Fe-Ti oxides found in the heavy mineral fraction. In the oxidized sediments, Fe was transported from the Fe-Ti oxide grains to quartz surfaces, where it was deposited as surface Fe(III) oxides mixed with kaolinite. Thus, the weathering of Fe-bearing minerals and the formation and dissolution of secondary Fe(III) oxides influenced the mobility of colloidal clay in the Cohansey Sand.

  10. Radar frequency dielectric dispersion in sandstone: Implications for determination of moisture and clay content

    NASA Astrophysics Data System (ADS)

    West, L. Jared; Handley, Kirk; Huang, Yi; Pokar, Magdeline

    2003-02-01

    The relationship between dielectric permittivity, water saturation, and clay content for the Sherwood Sandstone from NE England was characterized as part of a wider study of the vadose zone moisture dynamics and pollution vulnerability of this aquifer. Dielectric permittivity was measured over the full range of saturation levels, for various lithologies ranging from clean medium-grained sandstone to fine-grained sandstone containing up to 5% clay, using a specially constructed dielectric cell. Dielectric constant, Kr, is largely independent of frequency between 350 MHz and 1000 MHz. Below 350 MHz, Kr of fine-grained, clay-rich sandstone shows frequency dispersion. Tests on physical models of the sandstone consisting of a fine fraction of Ottawa Sand and montmorillonite clay indicate that the clay minerals within the sandstone are responsible for its frequency dispersive behavior. These tests also show that increasing pore fluid salinity increases dielectric dispersion at the lower end of the frequency range, which indicates that this arises from the interfacial Maxwell-Wagner mechanism associated with platy clay particles. Water saturated sand:clay mixtures show very low dielectric constants at high frequencies (over 650 MHz). This effect is independent of salinity and probably results from the layered geometric arrangement of solids, bound and free water within the swelling clay. The complex refractive index method (CRIM) with a mineral dielectric constant of about 5 provides a good match to the water saturation versus dielectric constant data for all Sherwood Sandstone lithologies at frequencies between 350 and 1000 MHz and for clay-poor sandstone at lower frequencies. Below 350 MHz the presence of a few percent of clay in some Sherwood Sandstone lithologies raises their CRIM best fit mineral dielectric constant substantially.

  11. Orientations of faults determined by premonitory shear zones

    NASA Astrophysics Data System (ADS)

    Johnson, Arvid M.

    1995-07-01

    The postulate of premonitory shear zones that the orientations of many faults are controlled by previously formed shear zones is a combination of theoretical analysis and the concept that faulting is the result of a group of hereditary processes. The hereditary nature of faulting processes is evinced by detailed observations of faulting in several, quite different materials in which the faults are end products of irreversible, localized deformation sequences such as pressure solution, particle rearrangement, layer reorientation, plastic flow or grain fracturing. The localized deformation is concentrated within shear zones that premonish the formation of faults. Thus, the problem of determining the orientations of faults becomes one of determining the preferred orientations of shear zones, which is the focus of the postulate of premonitory shear zones. The postulate is based on one definition and two assumptions: by definition, deformation becomes localized within a shear zone (the reason need not be specified); by assumption, the virtual shearing and dilation within the shear zone are coupled and the orientation that develops corresponds to the preferred orientation. The preferred orientation of the shear zone is defined as that which satisfies the mechanical and kinematical boundary conditions and maximizes, in some sense, the virtual work accomplished by the shearing and dilation. With the exception of coupling of the shearing and dilation through a coefficient of dilation, the analysis is only implicitly dependent on rheology; the only rheological requirement is that the properties allow localization. Although the postulate is based on very simple assumptions, and so its predictions are necessarily simple, it has a power that belies its simplicity. The preferred orientations of premonitory shear zones are consistent with orientations of shear zones and faults in laboratory specimens of Chelmsford granite. The coefficient of dilatancy in granite specimens about

  12. Physicochemical interaction of Escherichia coli cell envelopes and Bacillus subtilis cell walls with two clays and ability of the composite to immobilize heavy metals from solution.

    PubMed Central

    Walker, S G; Flemming, C A; Ferris, F G; Beveridge, T J; Bailey, G W

    1989-01-01

    Isolated Escherichia coli K-12 cell envelopes or Bacillus subtilis 168 cell walls were reacted with smectite or kaolinite clay in distilled deionized water (pH 6.0); unbound envelopes or walls were separated by sucrose density gradient centrifugation, and the extent of adsorption was calculated. At saturation, both clays adsorbed approximately 1.0 mg (dry weight) of envelopes or walls per mg (dry weight) of clay. Clays showed a preference for edge-on orientation with both walls and envelopes, which was indicative of an aluminum polynuclear bridging mechanism between the wall or envelope surface and the clay edge. The addition of heavy metals increased the incidence of planar surface orientations, which suggested that multivalent metal cation bridging was coming into play and was of increasing importance. The metal-binding capacity of isolated envelopes, walls, clays, and envelope-clay or wall-clay mixtures was determined by atomic absorption spectroscopy after exposure to aqueous 5.0 mM Ag+, Cu2+, Cd2+, Ni2+, Pb2+, Zn2+, and Cr3+ nitrate salt solutions at pHs determined by the buffering capacity of wall, envelope, clay, or composite system. The order of metal uptake was walls greater than envelopes greater than smectite clay greater than kaolinite clay for the individual components, and walls plus smectite greater than walls plus kaolinite greater than envelopes plus smectite greater than envelopes plus kaolinite for the mixtures. On a dry-weight basis, the envelope-clay and wall-clay mixtures bound 20 to 90% less metal than equal amounts of the individual components did.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:2516433

  13. Performance evaluation of indirect evaporative cooler using clay pot

    NASA Astrophysics Data System (ADS)

    Ramkumar, R.; Ragupathy, A.

    2016-05-01

    The aim of the experimental study is to investigate the performance of indirect evaporator cooler in hot and humid regions. A novel approach is implemented in the cooler using clay pot with different position (single, double and three pots) and different orientation as aligned and staggered position for potential and feasibility study. The clay pot is the ceramic material where the water filled inside the pot and due to the property of porosity, the water comes outer surface of the pot and contact with the air passing over the pot surface and air get cooled. A test rig was designed and fabricated to collect experimental data. The clay pots were arranged in aligned and staggered position. In our study heat transfer was analysed with various air velocity of 1m/s to 5m/s. The air temperature, relative humidity, pressure drop and effectiveness were measured and the performance of the evaporative cooler was evaluated. The analysis of the data indicated that cooling effectiveness improve with decrease of air velocity at staggered position. It was shown that staggered position has the higher performance (57%) at 1 m/s air velocity comparison with aligned position values at three pots position.

  14. Stabilization of montmorillonite clay in porous media by high-molecular-weight polymers

    SciTech Connect

    Zaitoun, A.; Berton, N. )

    1992-05-01

    In this paper a dynamic method is proposed for checking the stability of clay in porous media for different brine conditions and the stabilizing effect provided by several anionic and nonionic high-molecular-weight polymers. The method consists of injecting brine at decreasing salinity levels into clayey sandpacks until unstabilized permeability reduction is reached from the dislodging of clay particles that become trapped in pore restrictions. The last stable state before clay destablization is characterized by a critical salinity concentration (CSC). As expected, montmorillonite clay 5% dispersed in a sandpack is more stable in the presence of KCl than NaCl brines, giving CSC values of 5,000 and 27,500 ppm, respectively. Polyacrylamides are much better clay stabilizers than carboxymethyl cellulose (CMC) or xanthan gum (XG), lowering the CSC of KCl to 1,000 to 2,000 ppm and the CSC of NaCl to 6,000 to 7,000 ppm. A low-molecular-weight shear-degraded polyacrylamide is shown to keep good stabilizing power without inducing the high permeability reduction values obtained after adsorption of high-molecular-weight products. In addition to preventing clay migration, polyacrylamides are also shown to inhibit clay swelling.

  15. Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites

    PubMed Central

    Hamim, Salah U.; Singh, Raman P.

    2014-01-01

    Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface. PMID:27379285

  16. Characterization of Interlayer Cs+ in Clay Samples Using Secondary Ion Mass Spectrometry with Laser Sample Modification

    SciTech Connect

    G. S. Groenewold; R. Avci; C. Karahan; K. Lefebre; R. V. Fox; M. M. Cortez; A. K. Gianotto; J. Sunner; W. L. Manner

    2004-04-01

    Ultraviolet laser irradiation was used to greatly enhance the secondary ion mass spectrometry (SIMS) detection of Cs+ adsorbed to soil consisting of clay and quartz. Imaging SIMS showed that the enhancement of the Cs+ signal was spatially heterogeneous: the intensity of the Cs+ peak was increased by factors up to 100 for some particles but not at all for others. Analysis of standard clay samples exposed to Cs+ showed a variable response to laser irradiation depending on the type of clay analyzed. The Cs+ abundance was significantly enhanced when Cs+-exposed montmorillonite was irradiated and then analyzed using SIMS, which contrasted with the behavior of Cs+-exposed kaolinite, which displayed no Cs+ enhancement. Exposed illitic clays displayed modest enhancement of Cs+ upon laser irradiation, intermediate between that of kaolinite and montmorillonite. The results for Cs+ were rationalized in terms of adsorption to interlayer sites within the montmorillonite, which is an expandable phyllosilicate. In these locations, Cs+ was not initially detectable using SIMS. Upon irradiation, Cs+ was thermally redistributed, which enabled detection using SIMS. Since neither the illite nor the kaolinite is an expandable clay, adsorption to inner-layer sites does not occur, and either modest or no laser enhancement of the Cs+ signal is observed. Laser irradiation also produced unexpected enhancement of Ti+ from illite and kaolinite clays that contained small quantities of Ti, which indicates the presence of microscopic titanium oxide phases in the clay materials.

  17. Whose Orientations?

    ERIC Educational Resources Information Center

    Gutoff, Joshua

    2010-01-01

    This article presents the author's response to Jon A. Levisohn's article entitled "A Menu of Orientations in the Teaching of Rabbinic Literature." While the "menu" Levisohn describes in his groundbreaking work on orientations to the teaching of rabbinic texts will almost certainly be refined over time, even as it stands this article should be of…

  18. Orienteering injuries

    PubMed Central

    Folan, Jean M.

    1982-01-01

    At the Irish National Orienteering Championships in 1981 a survey of the injuries occurring over the two days of competition was carried out. Of 285 individual competitors there was a percentage injury rate of 5.26%. The article discusses the injuries and aspects of safety in orienteering. Imagesp236-ap237-ap237-bp238-ap239-ap240-a PMID:7159815

  19. Clarification of olive mill and winery wastewater by means of clay-polymer nanocomposites.

    PubMed

    Rytwo, Giora; Lavi, Roy; Rytwo, Yuval; Monchase, Hila; Dultz, Stefan; König, Tom N

    2013-01-01

    Highly polluted effluents from olive mills and wineries, among others, are unsuitable for discharge into standard sewage-treatment plants due to the large amounts of organic and suspended matter. Efficiency of all management practices for such effluents depends on an effective pretreatment that lowers the amount of suspended solids. Such pretreatments are usually based on three separate stages, taking a total of 2 to 6h: coagulation-neutralizing the colloids, flocculation-aggregating the colloids into larger particles, and separation via filtration or decanting. Previous studies have presented the concept of coagoflocculation based on the use of clay-polymer nanocomposites. This process adds a higher density clay particle to the flocs, accelerating the process to between 15 and 60 min. This study examined suitable nanocomposites based on different clays and polymers. The charge of the compounds increased proportionally to the polymer-to-clay ratio. X-ray diffraction (XRD) measurements indicated that in sepiolite-based nanocomposites there is no change in the structure of the mineral, whereas in smectite-based nanocomposites, the polymer intercalates between the clay layers and increases the spacing depending on the polymer-to-clay ratio. Efficiency of the coagoflocculation process was studied with a dispersion analyzer. Sequential addition of olive mill or winery effluents with a boosting dose of nanocomposites may yield a very efficient and rapid clarification pretreatment. PMID:23178773

  20. Soil-Water Characteristic Curves of Red Clay treated by Ionic Soil Stabilizer

    NASA Astrophysics Data System (ADS)

    Cui, D.; Xiang, W.

    2009-12-01

    The relationship of red clay particle with water is an important factor to produce geological disaster and environmental damage. In order to reduce the role of adsorbed water of red clay in WuHan, Ionic Soil Stabilizer (ISS) was used to treat the red clay. Soil Moisture Equipment made in U.S.A was used to measure soil-water characteristic curve of red clay both in natural and stabilized conditions in the suction range of 0-500kPa. The SWCC results were used to interpret the red clay behavior due to stabilizer treatment. In addition, relationship were compared between the basic soil and stabilizer properties such as water content, dry density, liquid limit, plastic limit, moisture absorption rate and stabilizer dosages. The analysis showed that the particle density and specific surface area increase, the dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. After treatment with the ISS, the geological disasters caused by the adsorbed water of red clay can be effectively inhibited.

  1. Mars, clays and the origins of life

    NASA Technical Reports Server (NTRS)

    Hartman, Hyman

    1989-01-01

    To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

  2. Morphological Evolution of High-Voltage Spinel LiNi(0.5)Mn(1.5)O4 Cathode Materials for Lithium-Ion Batteries: The Critical Effects of Surface Orientations and Particle Size.

    PubMed

    Liu, Haidong; Wang, Jun; Zhang, Xiaofei; Zhou, Dong; Qi, Xin; Qiu, Bao; Fang, Jianhui; Kloepsch, Richard; Schumacher, Gerhard; Liu, Zhaoping; Li, Jie

    2016-02-01

    An evolution panorama of morphology and surface orientation of high-voltage spinel LiNi(0.5)Mn(1.5)O4 cathode materials synthesized by the combination of the microwave-assisted hydrothermal technique and a postcalcination process is presented. Nanoparticles, octahedral and truncated octahedral particles with different preferential growth of surface orientations are obtained. The structures of different materials are studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy (TEM). The influence of various morphologies (including surface orientations and particle size) on kinetic parameters, such as electronic conductivity and Li(+) diffusion coefficients, are investigated as well. Moreover, electrochemical measurements indicate that the morphological differences result in divergent rate capabilities and cycling performances. They reveal that appropriate surface-tailoring can satisfy simultaneously the compatibility of power capability and long cycle life. The morphology design for optimizing Li(+) transport and interfacial stability is very important for high-voltage spinel material. Overall, the crystal chemistry, kinetics and electrochemical performance of the present study on various morphologies of LiNi(0.5)Mn(1.5)O4 spinel materials have implications for understanding the complex impacts of electrode interface and electrolyte and rational design of rechargeable electrode materials for lithium-ion batteries. The outstanding performance of our truncated octahedral LiNi(0.5)Mn(1.5)O4 materials makes them promising as cathode materials to develop long-life, high energy and high power lithium-ion batteries. PMID:26824793

  3. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G (Inventor)

    2013-01-01

    A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

  4. Evaluation of Biological and Physical Protection against Nuclease Degradation of Clay-Bound Plasmid DNA

    PubMed Central

    Demanèche, Sandrine; Jocteur-Monrozier, Lucile; Quiquampoix, Hervé; Simonet, Pascal

    2001-01-01

    In order to determine the mechanisms involved in the persistence of extracellular DNA in soils and to monitor whether bacterial transformation could occur in such an environment, we developed artificial models composed of plasmid DNA adsorbed on clay particles. We determined that clay-bound DNA submitted to an increasing range of nuclease concentrations was physically protected. The protection mechanism was mainly related to the adsorption of the nuclease on the clay mineral. The biological potential of the resulting DNA was monitored by transforming the naturally competent proteobacterium Acinetobacter sp. strain BD413, allowing us to demonstrate that adsorbed DNA was only partially available for transformation. This part of the clay-bound DNA which was available for bacteria, was also accessible to nucleases, while the remaining fraction escaped both transformation and degradation. Finally, transformation efficiency was related to the perpetuation mechanism, with homologous recombination being less sensitive to nucleases than autonomous replication, which requires intact molecules. PMID:11133458

  5. Interaction between viruses and clays in static and dynamic batch systems

    NASA Astrophysics Data System (ADS)

    Syngouna, V. I.; Chrysikopoulos, C. V.

    2009-04-01

    The transport and fate of viruses in subsurface formations are mainly governed by virus attachment onto the solid matrix and inactivation. Furthermore, virus attachment onto clay colloids is primarily controlled by electrostatic interactions between surfaces. Consequently, bacteriophage MS2 and ΦX174 were used as surrogates for human viruses in order to investigate the interaction between viruses and clay particles. The selected phyllosilicate clays were kaolinite and bentonite. Numerous reactor vessels were filled with 0.5 g of clay and 50 mL of sterile phosphate buffered saline solution (1.2 mM sodium chloride, 0.027 mM potassium chloride, and 0.1 mM phosphate buffer salts) and adjusted to a pH of 7. A series of static and dynamic experiments for various bacteriophage concentrations were conducted at two different temperatures. Half of the reactor vessels were placed in a refrigerator at 4

  6. Influence of clay swelling on the mechanical behaviour of Egyptian Helwan limestone

    NASA Astrophysics Data System (ADS)

    Aly, Nevin

    2016-04-01

    Clay minerals exist naturally in the majority of different Egyptian limestones types. Changes in the dimensions of clays during swelling / shrinking process induced by changes in the environmental conditions can result in acceleration the deterioration of the hosting stone. Petrographic investigation by scanning - electron microscope (SEM) of Helwan limestone (biomicritic limestone) revealed distribution of a typical smectite morphology (curled - leaf shape) beside abundance of glauconite pellets within the stone material. The clay frication extracted from Helwan reached 10% and oriented aggregates samples were analyzed by X- ray diffraction (XRD) and confirmed the identification of smectite as the main mineral in the clay frication. To study the effect of the clay content on the mechanical behavior of Helwan limestone, hygric swelling test was performed at first by using displacement sensor and then the effect of multiple wetting/ drying cycles on the stone strength was determined using unconfined compressive strength (UCS). Results revealed that there was a significant correlation between degree of swelling of the clay and strength of the limestone.

  7. Incorporation of phthalocyanines by cationic and anionic clays via ion exchange and direct synthesis

    SciTech Connect

    Carrado, K.A.; Botto, R.E.; Winans, R.E. ); Forman, J.E. )

    1993-04-01

    Phthalocyanines (Pc) and metallophthalocyanines were incorporated into the galleries of anionic and cationic clays via ion exchange and in situ crystallization of the synthetic clay layers. Intercalation compounds between the layered magnesium silicate clay hectorite and cationic phthalocyanines were directly prepared by refluxing for 2 days aqueous solutions of silica sol, magnesium hydroxide, lithium flouride, and either alcian blue dyes (Cu(II)Pc) or 15-crown-5 tetra-substituted phthalocyanine (15C5Pc). The CuPc dyes are tetrapositively charged through peripheral quaternary ammonium groups, whereas the 15C5Pc is electrically neutral. Anionic clays prepared by hydrolysis of mixed solutions of aluminum nitrate, magnesium nitrate, and copper(II) phthalocyaninetetrasulfonic acid, tetrasodium salt (CuPcTs) in sodium hydroxide resulted in crystallization of an intercalation compound between a layered double hydroxide (LDH) and this anionic Pc. The material prepared by ion exchange of CuPcTs into a wet, freshly prepared LDH was superior in crystallinity. The phthalocyanines are oriented parallel to cationic hectorite clay layers (gallery heights 4.5-6.5[angstrom]) and perpendicular to anionic layered double hydroxide clay layers (gallery height 18,2[angstrom]) in correlation with their hosts' respective layer charge densities. 32 refs., 4 figs., 2 tabs.

  8. Analysis of Oligonucleotide DNA Binding and Sedimentation Properties of Montmorillonite Clay Using Ultraviolet Light Spectroscopy

    PubMed Central

    Beall, Gary W.; Sowersby, Drew S.; Roberts, Rachel D.; Robson, Michael H.; Lewis, L. Kevin

    2009-01-01

    Smectite clays such as montmorillonite form complexes with a variety of biomolecules, including the nucleic acids DNA and RNA. Most previous studies of DNA adsorption onto clay have relied upon spectrophotometric analysis after separation of free nucleic acids from bound complexes by centrifugation. In the current work we demonstrate that such studies produce a consistent error due to (a) incomplete sedimentation of montmorillonite and (b) strong absorbance of the remaining clay at 260 nm. Clay sedimentation efficiency was strongly dependent upon cation concentration (Na+ or Mg2+) and on the level of dispersion of the original suspension. An improved clay:DNA adsorption assay was developed and utilized to assess the impact of metal counterions on binding of single-stranded DNA to montmorillonite. X-ray diffraction demonstrated, for the first time, formation of intercalated structures consistent with orientation of the DNA strands parallel to the clay surface. Observed gallery spacings were found to closely match values calculated utilizing atomistic modeling techniques. PMID:19061334

  9. Microtectonic analysis of an incipient thrust fault in Opalinus Clay.

    NASA Astrophysics Data System (ADS)

    Laurich, B.; Urai, J. L.; Desbois, G.; Vollmer, C.; Nussbaum, C.

    2014-12-01

    The microfabric of a fault rock controls the fault's mechanical and hydrological properties. Knowing the fabric is thus essential for estimating seismic behavior and potential fluid flow. We studied well-preserved core and outcrop samples from the Main Fault, an up to 3 m wide zone of approximately 10 m offset in the Mont Terri Underground Research Laboratory (CH), a site to evaluate long-term safety of radioactive waste disposal. We found four main structural elements: (1) slickensided shear surfaces, (2) veins, (3) fine-grained gouge, and (4) scaly clay fabric. We investigated each element by ultra-thin section microscopy, by broad-ion-beam scanning electron microscopy (BIB-SEM) and focused-ion-beam transmission electron microscopy (FIB-TEM), by X-ray diffraction crystallography (XRD) and by naked-eye analysis. We found extremely thin shear zones (<4μm) along which several samples broke, revealing slickensides. BIB-SEM and FIB-TEM showed that these thin shear zones comprise strongly aligned nano-sized clay particles. The porosity of the shear zones is dramatically reduced compared to the protolith. The strong alignment of clay particles, which wrap larger grains as quartz, calcite fossils and feldspar, yields a shiny, smooth surface morphology of the slickensides. Occasionally, calcite and celestite veins are associated to releasing sections such as risers of the slickenside. Gouge comprises much finer particles, a higher fabric intensity and a strong reduction in porosity and calcite content compared to the protolith. These findings suggest that gouge evolved by a cataclastic deformation mechanism aided by pressure solution of calcite. Scaly clay occurs in varying intensity and comprises thin shear zones, which sometimes act as flexural-slip faults of microfolds and C'-type shear bands. We propose that next to cataclastic processes, pressure solution and precipitation are important micro-scale mechanisms in faulting in Opalinus Clay and thus need to be

  10. Unique solvatochromism of a membrane composed of a cationic porphyrin-clay complex.

    PubMed

    Takagi, Shinsuke; Shimada, Tetsuya; Masui, Dai; Tachibana, Hiroshi; Ishida, Yohei; Tryk, Donald A; Inoue, Haruo

    2010-04-01

    A novel optically transparent membrane composed of porphyrin-clay mineral complexes was developed. Reversible solvatochromism behavior of the membrane was successfully observed, due to an orientation change of porphyrin in the clay interlayer space. The lambda(max) value of porphyrin was 423 nm in acetone, while it was 464 nm in hexane. The color of the membrane changed from pink to green through to brown, when Sn porphyrin was used. The mechanism for solvatochromism in the present system is very unique compared to those for conventionally reported materials. PMID:20229990

  11. Maya blue: a clay-organic pigment?

    PubMed

    Van Olphen, H

    1966-11-01

    Maya Blue, a pigment used by the Mayas in Yucatan, is remarkably stable: the color is not destroyed by hot concentrated mineral acids or by heating to about 250 degrees C. The principal constituent is the colorless mineral attapulgite. It is proposed that the pigment is an adsorption complex of attapulgite and natural indigo; a synthetic equivalent may be prepared from attapulgite and either indoxylester or indigo, or by applying the vat-dyeing technique, with reduced indigo.The low dye content of the pigment (less than 0.5 percent) indicates that the dye is absorbed only on the external surfaces of the attapulgite particles and not throughout the channels in their structures. The complex as such is not stable to acids, but the stability displayed by Maya Blue is achieved simply by heating the complex to from 75 degrees to 150 degrees C for several days. An analogous stable pigment can be prepared from sepiolite and indigo. No stable pigments could be prepared from clays with platelike structures or from zeolites. PMID:17778806

  12. Analyzing Orientations

    NASA Astrophysics Data System (ADS)

    Ruggles, Clive L. N.

    Archaeoastronomical field survey typically involves the measurement of structural orientations (i.e., orientations along and between built structures) in relation to the visible landscape and particularly the surrounding horizon. This chapter focuses on the process of analyzing the astronomical potential of oriented structures, whether in the field or as a desktop appraisal, with the aim of establishing the archaeoastronomical "facts". It does not address questions of data selection (see instead Chap. 25, "Best Practice for Evaluating the Astronomical Significance of Archaeological Sites", 10.1007/978-1-4614-6141-8_25) or interpretation (see Chap. 24, "Nature and Analysis of Material Evidence Relevant to Archaeoastronomy", 10.1007/978-1-4614-6141-8_22). The main necessity is to determine the azimuth, horizon altitude, and declination in the direction "indicated" by any structural orientation. Normally, there are a range of possibilities, reflecting the various errors and uncertainties in estimating the intended (or, at least, the constructed) orientation, and in more formal approaches an attempt is made to assign a probability distribution extending over a spread of declinations. These probability distributions can then be cumulated in order to visualize and analyze the combined data from several orientations, so as to identify any consistent astronomical associations that can then be correlated with the declinations of particular astronomical objects or phenomena at any era in the past. The whole process raises various procedural and methodological issues and does not proceed in isolation from the consideration of corroborative data, which is essential in order to develop viable cultural interpretations.

  13. On Techniques to Characterize and Correlate Grain Size, Grain Boundary Orientation and the Strength of the SiC Layer of TRISO Coated Particles: A Preliminary Study

    SciTech Connect

    I.J.van Rooyen; J.L. Dunzik Gougar; T. Trowbridge; Philip M van Rooyen

    2012-10-01

    The mechanical properties of the silicon carbide (SiC) layer of the TRi-ISOtropic (TRISO) coated particle (CP) for high temperature gas reactors (HTGR) are performance parameters that have not yet been standardized by the international HTR community. Presented in this paper are the results of characterizing coated particles to reveal the effect of annealing temperature (1000 to 2100°C) on the strength and grain size of unirradiated coated particles. This work was further expanded to include possible relationships between the grain size and strength values. The comparative results of two strength measurement techniques and grain size measured by the Lineal intercept method are included. Preliminary grain boundary characterization results determined by electron backscatter diffraction (EBSD) are included. These results are also important for future fission product transport studies, as grain boundary diffusion is identified as a possible mechanism by which 110mAg, one of the fission activation products, might be released through intact SiC layers. Temperature is a parameter known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. Recommendations and future work will also be briefly discussed.

  14. Origin, Behavior and Texture of Clay Minerals in Mongolian Active Fault of Bogd and Comparison with SAFOD Fault Gouge

    NASA Astrophysics Data System (ADS)

    Wenk, H.; Buatier, M.; Chauvet, A.; Kanitpanyacharoen, W.

    2010-12-01

    Fault gouges are generally considered as the highly deformed zone corresponding to the localization of shear during seismic events. Clays are ubiquitous minerals in fault gouges but the origin is unclear. They can form as a result of break up of inherited phyllosilicates during faulting, or during co- or post- deformation events or even during interseismic creeping. In this study, we aim to characterize the origin and nature of the clay minerals, to observe the microtexture and preferred orientation of clay at various scales in order to understand the behavior of clay mineral in seismic faults. The investigation relied on x-ray powder patterns, SEM, TEM and high energy synchrotron x-ray diffraction. The major clay components are smectite, illite-smectite, illite-mica and kaolinite. Our observations suggest that the protolith and the fault rock of the Bogd and paleo-Bogd faults in Mongolia were highly altered by fluids. The fluid-rock interactions allows clay minerals to form and to precipitate kaolinite and smectite. Thus, newly formed clay minerals are heterogeneously distributed in the fault zone. The decrease of smectite component of the highly deformed samples suggests a dehydration process during deformation, leading to illite precipitation. From synchrotron diffraction images, volume fractions and preferred orientation were analyzed. Our analysis shows that texture strength of constituent clays is very weak ranging from 1.05 to 2.59 m.r.d., which is consistent with similar data from SAFOD fault gouge. The clays minerals of the Bogd fault favors the slip weakening behavior of the fault.

  15. Clay Corner: Light up a Turkey.

    ERIC Educational Resources Information Center

    Hiller, Peter

    1998-01-01

    Presents two activities that enable students to work with clay: a tile project and turkey candle-holders. Explains that before students actually create their own projects, they get an opportunity to experience the clay itself. Asserts that the new vocabulary, unusual equipment, and intriguing techniques make ceramics a motivating activity. (CMK)

  16. Clay smear: Review of mechanisms and applications

    NASA Astrophysics Data System (ADS)

    Vrolijk, Peter J.; Urai, Janos L.; Kettermann, Michael

    2016-05-01

    Clay smear is a collection of fault processes and resulting fault structures that form when normal faults deform layered sedimentary sections. These elusive structures have attracted deep interest from researchers interested in subsurface fluid flow, particularly in the oil and gas industry. In the four decades since the association between clay-smear structures and oil and gas accumulations was introduced, there has been extensive research into the fault processes that create clay smear and the resulting effects of that clay smear on fluid flow. We undertake a critical review of the literature associated with outcrop studies, laboratory and numerical modeling, and subsurface field studies of clay smear and propose a comprehensive summary that encompasses all of these elements. Important fault processes that contribute to clay smear are defined in the context of the ratio of rock strength and in situ effective stresses, the geometric evolution of fault systems, and the composition of the faulted section. We find that although there has been progress in all avenues pursued, progress has been uneven, and the processes that disrupt clay smears are mostly overlooked. We highlight those research areas that we think will yield the greatest benefit and suggest that taking these emerging results within a more process-based framework presented here will lead to a new generation of clay smear models.

  17. Dehydration-induced luminescence in clay minerals

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  18. Desert varnish: the importance of clay minerals.

    PubMed

    Potter, R M; Rossman, G R

    1977-06-24

    Desert varnish has been characterized by infrared spectroscopy, x-ray diffraction, and electron microscopy. It is a distinct morphological entity having an abrupt boundary with the underlying rock. Clay minerals comprise more than 70 percent of the varnish. Iron and manganese oxides constitute the bulk of the remainder and are dispersed throughout the clay layer. PMID:17776923

  19. Sectioning Clay Models Makes Anatomy & Development Tangible

    ERIC Educational Resources Information Center

    Howell, Carina Endres; Howell, James Endres

    2010-01-01

    Clay models have proved to be useful teaching aids for many topics in biology that depend on three-dimensional reasoning. Students studying embryonic development struggle to mentally reconstruct the three-dimensional structure of embryos and larvae by observing prepared slides of cross-sectional slices. Students who build clay models of embryos…

  20. The colloidal chemistry of ceramic clays

    NASA Technical Reports Server (NTRS)

    Phelps, G. W.

    1984-01-01

    The colloidal chemistry and mineralogy of two argil minerals were studied. Deposits of kaolin and of ceramic clays in the United States and England are discussed for the probable mechanism of formation. The structural modifications of the bed, original material associated with the clays and the proper use of flocculants are discussed.

  1. Preparation and characterization of 'green' hybrid clay-dye nanopigments

    NASA Astrophysics Data System (ADS)

    Kaya, Mehmet; Onganer, Yavuz; Tabak, Ahmet

    2015-03-01

    We obtained a low cost and abundant nanopigment material composed of Rhodamine B (Rh-B) organic dye compound and Unye bentonite (UB) clay from Turkey. The characterization of the nanopigment was investigated using scanning electron microscopy (SEM), particle size distribution, powder X-ray diffraction (PXRD), Fourier transformed infra-red spectroscopy (FT-IR) and thermal analysis techniques. According to the result of texture analyses, we showed that the particle size distribution (d: 0.5-mean distribution) of Rh-B/UB nanopigment material was around 100 nm diameter. It was also demonstrated that the samples had a particle size around nm diameter in SEM images. As seen in the PXRD and thermal analysis, there is a difference in basal spacing by 1.46° (2θ) and a higher mass loss by 7.80% in the temperature range 200-500 °C compared to the raw bentonite.

  2. Assessing the interactions of a natural antibacterial clay with model Gram-positive and Gram-negative human pathogens

    NASA Astrophysics Data System (ADS)

    Londono, S. C.; Williams, L. B.

    2013-12-01

    The emergence of antibiotic resistant bacteria and increasing accumulations of antibiotics in reclaimed water, drive the quest for new natural antimicrobials. We are studying the antibacterial mechanism(s) of clays that have shown an ability to destroy bacteria or significantly inhibit their growth. One possible mode of action is from soluble transition metal species, particularly reduced Fe, capable of generating deleterious oxygen radical species. Yet another possibility is related to membrane damage as a consequence of physical or electrostatic interaction between clay and bacteria. Both mechanisms could combine to produce cell death. This study addresses a natural antibacterial clay from the NW Amazon basin, South America (AMZ clay). Clay mineralogy is composed of disordered kaolinite (28.9%), halloysite (17.8%) illite (12%) and smectite (16.7%). Mean particle size is 1.6μm and total and specific surface area 278.82 and 51.23 m2/g respectively. The pH of a suspension (200mg/ml) is 4.1 and its Eh is 361mV after 24h of equilibration. The ionic strength of the water in equilibrium with the clay after 24 h. is 6 x10-4M. These conditions, affect the element solubility, speciation, and interactions between clay and bacteria. Standard microbiological methods were used to assess the viability of two model bacteria (Escherichia coli and Bacillus subtilis) after incubation with clay at 37 degC for 24 hrs. A threefold reduction in bacterial viability was observed upon treatment with AMZ clay. We separated the cells from the clay using Nycodenz gradient media and observed the mounts under the TEM and SEM. Results showed several membrane anomalies and structural changes that were not observed in the control cells. Additionally, clay minerals appeared in some places attached to cell walls. Experiments showed that exchanging AMZ clay with KCl caused loss of antibacterial property. Among the exchangeable -and potentially toxic- ions we measured Al+3, Cu+2, Zn+2, Ba+2 and Co+2

  3. Active containment systems incorporating modified pillared clays

    SciTech Connect

    Lundie, P. |; McLeod, N.

    1997-12-31

    The application of treatment technologies in active containment systems provides a more advanced and effective method for the remediation of contaminated sites. These treatment technologies can be applied in permeable reactive walls and/or funnel and gate systems. The application of modified pillared clays in active containment systems provides a mechanism for producing permeable reactive walls with versatile properties. These pillared clays are suitably modified to incorporate reactive intercalatants capable of reacting with both a broad range of organic pollutants of varying molecular size, polarity and reactivity. Heavy metals can be removed from contaminated water by conventional ion-exchange and other reactive processes within the clay structure. Complex contamination problems can be addressed by the application of more than one modified clay on a site specific basis. This paper briefly describes the active containment system and the structure/chemistry of the modified pillared clay technology, illustrating potential applications of the in-situ treatment process for contaminated site remediation.

  4. Preconsolidation versus aging behavior of kaolinite clay

    SciTech Connect

    Athanasopoulos, G.A. )

    1993-06-01

    Results of resonant column tests were used to determine the effects of overconsolidation ratio (OCR) and of aging on the normalized rate of secondary increase N[sub G] of low-amplitude shear modulus G[sub 0] of a remolded kaolinite clay. The value of N[sub G] decreased approximately linearly with the logarithm of OCR and with the logarithm of duration of aging of the clay. The similarity of behavior provided a basis for establishing an equivalency between age-and-stress-induced equivalent overconsolidation for the clay in question. It was concluded that up to a certain limiting duration of aging the age-induced OCR increases linearly with elapsed time, whereas the effect starts diminishing for longer durations of aging. It is suggested that the results of similar studies on natural clay soils be used for predicting the long-term behavior of clays from the results of short-duration tests.

  5. Electrokinetic potentials of clay surfaces modified by polymers

    SciTech Connect

    Sondi, I.; Pravdic, V.; Milat, O.

    1997-05-01

    This paper describes the influence of two polymers, fulvic acid (FA) and polyacrylic acids (PAAs) of comparable molecular mass, on the electrokinetic potential of model surfaces encountered in clay minerals: silica (SiO{sub 2}), aluminum oxide ({gamma}-Al{sub 2}O{sub 3}), and gibbsite [{gamma}-Al(OH){sub 3}]. Measurements at pH 6.5 {+-} 0.2 show that FA and PAAs modify the potentials of aluminum oxide and gibbsite, but leave the silica surface unchanged. A chlorite clay mineral (ripidolite), milled to increase the numbers of oxy-hydroxy groups at newly created surfaces, was exposed to FA and PAAs, carriers of carboxylic groups, to study their influence on electrokinetic potential. The key to the interaction is that polymers hold metal ions (Al, Mg, Fe) in the edge surfaces, while siloxane groups show limited interaction or none at all. The results offer an explanation of why clay mineral particles are always negatively charged in natural waters.

  6. Crystallization and textural porosity of synthetic clay minerals.

    SciTech Connect

    Carrado, K. A.; Csencsits, R.; Thiyagarajan, P.; Seifert, S.; Macha, S. M.; Harwood, J.; Univ. of Illinois at Chicago; IIT

    2002-12-01

    The crystallization of synthetic layered magnesium silicate hectorite clays from both silica sol and organosilane sources is compared. For the silica sol-derived clays, a templating method is employed wherein organic or polymeric molecules are included during clay crystallization that are then removed from the composites via calcination. The mechanism of silane-derived hectorite formation is followed by XRD, TGA, 29Si MAS NMR, and small angle X-ray scattering (SAXS), and results are compared to those obtained for the sol-derived hectorite. The mechanism appears to be similar but the rate is approximately doubled when the silane is used rather than silica sol. Analytical transmission electron microscopy (TEM) is exploited to glean structural morphology information towards resolving the nature of the resulting pore network structures. Results are compared with nitrogen adsorption-desorption isotherm behavior; dominant hysteresis loops are present in the type IV isotherms. Pore size distributions based on both the adsorption and desorption isotherms are compared. Small angle neutron scattering (SANS) experiments reveal that the average particle size increases as synthetic laponite < sol-derived hectorite < silane-derived hectorite < natural hectorite. Contrast matching SANS studies in aqueous and organic solvents are carried out to extract information about pore accessibility.

  7. Pozzolan Obtained by Mechanochemical Treatment of Kaolinite Clay

    NASA Astrophysics Data System (ADS)

    Mitrović, Aleksandra A.

    2011-12-01

    Pozzolans are supplementary materials added to Portland cement in order to increase the mechanical strength and durability of concrete structures. A number of thermal, mechanical and chemical methods have been used to activate the reactive potential of pozzolanic materials. The aim of the study is to obtain pozzolana, from Serbian kaolinite clay by mechanochemical treatment. Kaolinite clay Garaši was subjected to mechanical treatment during different times of milling. The changes were monitored using particle size distribution (PSD) analyses, thermal methods [thermogravimetric analysis (TGA), and differential thermal analysis (DTA)] and X-ray diffraction methods (XRD). The pozzolanic activity was determined using Chapelle method. Milling withing 20 min influences particle size decrease and after that time continuous increase. XDR analysis indicates gradual decrease of cristallinity with prolonged milling time. The higher values for pozzolanic activitie, expressed through consumption of gCa(OH)2 per gPozzolana are 0.78 and 0.77, and they were obtained for milling times 20 and 40 min, respectively. The values are comparable with commercial pozzolan—metakaolin. The results indicates that milling has caused the disintegration of particles and the consequent formation of new active surfaces in addition to changes in its physico-chemical properties that decrease its crystallinity (through amorphization) and increase it reactivity.

  8. Color measurement of methylene blue dye/clay mixtures and its application using economical methods

    NASA Astrophysics Data System (ADS)

    Milosevic, Maja; Kaludjerovic, Lazar; Logar, Mihovil

    2016-04-01

    Identifying the clay mineral components of clay materials by staining tests is rapid and simple, but their applicability is restricted because of the mutual interference of the common components of clay materials and difficulties in color determination. The change of color with concentration of the dye is related to the use of colorants as a field test for identifying clay minerals and has been improved over the years to assure the accuracy of the tests (Faust G. T., 1940). The problem of measurement and standardization of color may be solved by combination of colors observed in staining tests with prepared charts of color chips available in the Munsell Book of Color, published by Munsell Color Co. Under a particular set of illumination conditions, a human eye can achieve an approximate match between the color of the dyed clay sample and that of a standard color chip, even though they do have different spectral reflectance characteristics. Experiments were carried out with diffuse reflectance spectroscopy on selected clay samples (three montmorillonite, three kaolinite and one mix-layer clay samples) saturated with different concentration of methylene blue dye solution. Dominant wavelength and purity of the color was obtained on oriented dry samples and calculated by use of the I. C. I. (x, y) - diagram in the region of 400-700 nm (reflectance spectra) without MB and after saturation with different concentrations of MB solutions. Samples were carefully photographed in the natural light environment and processed with user friendly and easily accessible applications (Adobe color CC and ColorHexa encyclopedia) available for android phones or tablets. Obtained colors were compared with Munsell standard color chips, RGB and Hexa color standards. Changes in the color of clay samples in their interaction with different concentration of the applied dye together with application of economical methods can still be used as a rapid fieldwork test. Different types of clay

  9. Effect of wet grinding on structural properties of ball clay

    SciTech Connect

    Purohit, A. Chander, S.; Dhaka, M. S.; Hameed, A.; Singh, P.; Nehra, S. P.

    2015-05-15

    In this paper, the effect of wet grinding on structural properties of ball clay is undertaken. The wet grinding treatment was performed employing ball and vibro mills for different time spells of 2, 4, 8 and 16 hours. The structural properties were carried out using X-ray diffraction (XRD). The structure of ground samples is found to be simple cubic. The crystallographic parameters are calculated and slight change in lattice constant, inter planner spacing and particle size is observed with grinding treatment. The results are in agreement with the available literature.

  10. Sorption of high explosives to water-dispersible clay: influence of organic carbon, aluminosilicate clay, and extractable iron.

    PubMed

    Dontsova, Katerina M; Hayes, Charolett; Pennington, Judith C; Porter, Beth

    2009-01-01

    Explosives in soils can present environmental problems for military installations. Fine, mobile particles represent the most reactive fraction of the soil and, therefore, are expected to adsorb explosives and potentially facilitate their transport. The objective of this study was to determine the relative significance of phyllosilicate clay, organic matter, and two forms of extractable iron in adsorption of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by the colloidal water-dispersible clay (WDC) fraction of the soil. The WDC fraction of two mineral and one organic soil was separated and then treated to remove organic carbon (OC) and several forms of iron (Fe(o), oxalate extractable, and Fe(d), dithionite-citrate extractable). Adsorption coefficients were determined for whole soils, untreated, and treated WDC. For mineral soils, adsorption of TNT and RDX on the WDC was greater than on the whole soil. The presence of OC increased explosives sorption by WDC. When OC was removed, iron interfered with TNT sorption. In the presence of OC, removal of Fe(o) decreased RDX adsorption and increased TNT adsorption indicating different adsorption mechanisms. Organic carbon was a more significant indicator of explosives adsorption by WDC than clays or iron oxides and hydroxides. Therefore, OC is the most likely medium for facilitated transport of TNT and RDX. PMID:19465721

  11. Phosphates in some missouri refractory clays

    USGS Publications Warehouse

    Hall, R.B.; Foord, E.E.; Keller, D.J.; Keller, W.D.

    1997-01-01

    This paper describes in detail phosphate minerals occurring in refractory clays of Missouri and their effect on the refractory degree of the clays. The minerals identified include carbonate-fluorapatite (francolite), crandallite, goyazite, wavellite, variscite and strengite. It is emphasized that these phosphates occur only in local isolated concentrations, and not generally in Missouri refractory clays. The Missouri fireclay region comprises 2 districts, northern and southern, separated by the Missouri River In this region, clay constitutes a major part of the Lower Pennsylvanian Cheltenham Formation. The original Cheltenham mud was an argillic residue derived from leaching and dissolution of pre-Pennsylvanian carbonates. The mud accumulated on a karstic erosion surface truncating the pre-Cheltenham rocks. Fireclays of the northern district consist mainly of poorly ordered kaolinite, with variable but minor amounts of illite, chlorite and fine-grained detrital quartz. Clays of the southern district were subjected to extreme leaching that produced well-ordered kaolinite flint clays. Local desilication formed pockets of diaspora, or more commonly, kaolinite, with oolite-like nubs or burls of diaspore ("burley" clay). The phosphate-bearing materials have been studied by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectral analysis (SEM-EDS) and chemical analysis. Calcian goyazite was identified in a sample of diaspore, and francolite in a sample of flint clay. A veinlet of wavellite occurs in flint clay at one locality, and a veinlet of variscite-strengite at another locality. The Missouri flint-clay-hosted francolite could not have formed in the same manner as marine francolite The evidence suggests that the Cheltenham francolite precipitated from ion complexes in pore water nearly simultaneously with crystallization of kaolinite flint clay from an alumina-silica gel. Calcian goyazite is an early diagenetic addition to its diaspore host

  12. Particle size and X-ray analysis of Feldspar, Calvert, Ball, and Jordan soils

    NASA Technical Reports Server (NTRS)

    Chapman, R. S.

    1977-01-01

    Pipette analysis and X-ray diffraction techniques were employed to characterize the particle size distribution and clay mineral content of the feldspar, calvert, ball, and jordan soils. In general, the ball, calvert, and jordan soils were primarily clay size particles composed of kaolinite and illite whereas the feldspar soil was primarily silt-size particles composed of quartz and feldspar minerals.

  13. A minimalistic microbial food web in an excavated deep subsurface clay rock.

    PubMed

    Bagnoud, Alexandre; de Bruijn, Ino; Andersson, Anders F; Diomidis, Nikitas; Leupin, Olivier X; Schwyn, Bernhard; Bernier-Latmani, Rizlan

    2016-01-01

    Clay rocks are being considered for radioactive waste disposal, but relatively little is known about the impact of microbes on the long-term safety of geological repositories. Thus, a more complete understanding of microbial community structure and function in these environments would provide further detail for the evaluation of the safety of geological disposal of radioactive waste in clay rocks. It would also provide a unique glimpse into a poorly studied deep subsurface microbial ecosystem. Previous studies concluded that microorganisms were present in pristine Opalinus Clay, but inactive. In this work, we describe the microbial community and assess the metabolic activities taking place within borehole water. Metagenomic sequencing and genome-binning of a porewater sample containing suspended clay particles revealed a remarkably simple heterotrophic microbial community, fueled by sedimentary organic carbon, mainly composed of two organisms: a Pseudomonas sp. fermenting bacterium growing on organic macromolecules and releasing organic acids and H2, and a sulfate-reducing Peptococcaceae able to oxidize organic molecules to CO(2). In Opalinus Clay, this microbial system likely thrives where pore space allows it. In a repository, this may occur where the clay rock has been locally damaged by excavation or in engineered backfills. PMID:26542073

  14. Chemistry and mineralogy of clay minerals in Asian and Saharan dusts and the implications for iron availability

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Achterberg, E. P.

    2014-06-01

    Mineral dust supplied to remote ocean regions stimulates phytoplankton growth through delivery of micronutrients, notably iron (Fe). Although attention is usually paid to Fe (hydr)oxides as major sources of available Fe, Fe-bearing clay minerals are typically the dominant phase in mineral dust. The mineralogy and chemistry of clay minerals in dust particles, however, are largely unknown. We conducted microscopic identification and chemical analysis of the clay minerals in Asian and Saharan dust particles. Cross-sectional slices of dust particles were prepared by focused ion beam (FIB) techniques and analyzed by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS). TEM images of FIB slices revealed that clay minerals occurred as either nano-thin platelets or relatively thick plates. The nano-thin platelets included illite, smectite, illite-smectite mixed layers and their nanoscale mixtures (illite-smectite series clay minerals, ISCMs) which could not be resolved with an electron microbeam. EDXS chemical analysis of the clay mineral grains revealed that the average Fe content was 5.8% in nano-thin ISCM platelets assuming 14% H2O, while the Fe content of illite and chlorite was 2.8 and 14.8%, respectively. In addition, TEM and EDXS analyses were performed on clay mineral grains dispersed and loaded on microgrids. The average Fe content of clay mineral grains was 6.7 and 5.4% in Asian and Saharan dusts, respectively. A comparative X-ray diffraction analysis of bulk dusts showed that Saharan dust was more enriched in clay minerals than in Asian dust, while Asian dust was more enriched in chlorite. The average Fe / Si, Al / Si and Fe / Al molar ratios of the clay minerals, compared to previously reported chemistries of mineral dusts and leached solutions, indicated that dissolved Fe originated from clay minerals. Clay minerals, in particular nanocrystalline ISCMs and Fe-rich chlorite are important sources of available Fe in

  15. Natural Ferrihydrite as an Agent for Reducing Turbidity Caused by Suspended Clays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The turbidity of water can be reduced by the addition of positively charged compounds which coagulate negatively charged clay particles in suspension causing them to flocculate. This research was conducted to determine the effectiveness of the Fe oxide mineral ferrihydrite as a flocculating agent fo...

  16. Soil aggregate stability as affected by clay mineralogy and polyacrylamide addition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The addition of polyacrylamide (PAM) to soil leads to stabilization of existing aggregates and improved bonding between, and aggregation of adjacent soil particles However, the dependence of PAM efficacy as an aggregate stabilizing agent on soil-clay mineralogy has not been studied. Sixteen soil sam...

  17. Polyacrylamide effects on aggregate and structure stability of soils with different clay mineralogy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adding anionic polyacrylamide (PAM) to soils stabilizes existing aggregates and improves bonding between and aggregation of soil particles. However, the dependence of PAM efficacy as an aggregate stabilizing agent with soils having different clay mineralogy has not been studied. Sixteen soil samples...

  18. Chromate adsorption on acid-treated and amines-modified clay

    NASA Astrophysics Data System (ADS)

    Hajjaji, M.; Beraa, A.

    2015-03-01

    Acid-treated montmorillonite-rich clay and amines (methylamine, morpholine, and aniline)-modified clay adsorbents were investigated and their abilities to remove chromate from aqueous solution were studied. For the later purpose, kinetic studies were carried out under different operating conditions (chromate concentration, adsorbent content, and temperature), and adsorption isotherm measurements were performed. It was found that the kinetic of adsorption was fast and the data followed the pseudo-second rate equation. The rate of adsorption was controlled by the intra-particle diffusion and mass transfer through the liquid film, and the relative importance of these limiting steps depended on the operating conditions. Chromate adsorption was an endothermic process and took place spontaneously by physisorption. The free energy at 25 ≤ T ≤ 40 °C varied from -1.5 to -46 kJ/mol. Adsorption isotherms of Na+-saturated clay (AN), acid-treated clay (AA), and methylamine-clay and morpholine-clay (A-Me, A-Mo) were type V, whereas those of aniline-clay (A-An) were type III. The estimated maximum uptakes were 105, 29, 15, 11, and 10 mmol/kg for A-An, AN, A-Mo, AA, and A-Me, respectively. The mechanism of chromate adsorption was discussed based on the shape of the isotherms. Considering for instance the most efficient absorbent (A-An), the isotherm followed the Freundlich equation and hydrogen chromate (the main stable form at working pH) adsorbed to solid particles once aniline species were entirely desorbed.

  19. Wave-induced ripple development in mixed clay-sand substrates

    NASA Astrophysics Data System (ADS)

    Wu, Xuxu; Parsons, Daniel; Baas, Jaco H.; Mouazé, Dominique; McLelland, Stuart; Amoudry, Laurent; Eggenhuisen, Jorris; Cartigny, Matthieu; Ruessink, Gerben

    2016-04-01

    This paper reports on a series of experiments that aim to provide a fuller understanding of ripple development within clay-sand mixture substrates under oscillatory flow conditions. The work was conducted in the Total Environment Simulator at the University of Hull and constituted 6 separate runs, in which 5 runs were conducted under identical sets of regular waves (an additional run was conducted under irregular waves, but is not discussed in present paper). The bed content was systematically varied in its composition ranging from a pure sand bed through to a bed comprising 7.4% clay. A series of state-of-the-art measurements were employed to quantify interactions of near-bed hydrodynamics, sediment transport, and turbulence over rippled beds formed by wave action, during and after, each run. The experimental results demonstrate the significant influence of the amount of cohesive clay materials in the substrate on ripple evolution under waves. Most importantly, addition of clay in the bed dramatically slowed down the rate of ripple development and evolution. The equilibrium time of each run increased exponentially from 30 minutes under the control conditions of a pure sand bed, rising to ~350 minutes for the bed with the highest fraction of clay. The paper discusses the slower ripple growth rates with higher cohesive fractions, via an influence on critical shear, but highlights that the end equilibrium size of ripples is found to be independent of increasing substrate clay fraction. The suspended particles mass (SPM) concentration indicates that clay particles were suspended and winnowed by wave action. Additionally, laser granulometry of the final substrates verified that ripple crests were composed of pure sand layers that were absent at ripple troughs, reflecting a relatively higher winnowing efficiency at wave ripples crest. The winnowing process and its efficiency is inexorably linked to wave ripple development and evolution. The implications of the results

  20. Release of nanoclay and surfactant from polymer-clay nanocomposites into a food simulant.

    PubMed

    Xia, Yining; Rubino, Maria; Auras, Rafael

    2014-12-01

    Release assessment of organo-modified montmorillonite (O-MMT) nanoclay and the organo-modifiers (surfactants) was performed on two types of polymer–clay nanocomposites: polypropylene (PP) and polyamide 6 (PA6) with O-MMT. In accordance with ASTM D4754-11, nanocomposite films were exposed to ethanol as a fatty-food simulant at 70 °C. The release of O-MMT, with Si and Al used as the nanoclay markers, was evaluated by graphite furnace atomic absorption spectrometry. The nanoclay particles released in ethanol were visualized by transmission electron microscopy (TEM). More nanoclay particles were released from PP–clay films (0.15 mg L(–1)) than from PA6–clay films (0.10 mg L(–1)), possibly due to the lack of interaction between the nanoclay and PP as indicated by the structure and morphology in the TEM images. The surfactant release was quantified by a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. A substantial amount of surfactant was released into ethanol (3.5 mg L(–1) from PP–clay films and 16.2 mg L(–1) from PA6–clay films), indicating changes in the nanoclay structure within the nanocomposite while it was exposed to ethanol. This research has provided information for the determination of exposure doses of nanoclay and surfactant in biosystems and the environment, which enabled the risk assessment. PMID:25369541

  1. Discrete Analysis of Clay Layer Tensile Strength

    NASA Astrophysics Data System (ADS)

    Lê, T. N. H.; Plé, O.; Villard, P.; Gotteland, P.; Gourc, J. P.

    2009-06-01

    The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover.

  2. Industrial Orientation.

    ERIC Educational Resources Information Center

    Rasor, Leslie; Brooks, Valerie

    These eight modules for an industrial orientation class were developed by a project to design an interdisciplinary program of basic skills training for disadvantaged students in a Construction Technology Program (see Note). The Drafting module overviews drafting career opportunities, job markets, salaries, educational requirements, and basic…

  3. Stereo soft x-ray microscopy and elemental mapping of hematite and clay suspensions

    SciTech Connect

    Gleber, S.-C.; Thieme, J.; Chao, W.; Fischer, P.

    2008-09-01

    The spatial arrangements of hematite particles within aqueous soil and clay samples are investigated with soft X-ray microscopy, taking advantage of the elemental contrast at the Fe-L edge around E = 707 eV. In combination with stereo microscopy, information about spatial arrangements are revealed and correlated to electrostatic interactions of the different mixtures. Manipulation of a sample mounted to the microscope is possible and particles added while imaging can be detected.

  4. Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

    USGS Publications Warehouse

    Solum, J.G.; van der Pluijm, B.A.; Peacor, D.R.

    2005-01-01

    Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ???40% in 1Md illite relative to protolith, whereas altered protolith in the damage zone is enriched ???40% in illite-smectite relative to gouge and up to ???50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1Md) gouge illite (63??2 Ma) and illite-smectite in the damage zone (60??2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone. ?? 2005 Elsevier Ltd. All rights reserved.

  5. Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

    NASA Astrophysics Data System (ADS)

    Solum, John G.; van der Pluijm, Ben A.; Peacor, Donald R.

    2005-09-01

    Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ˜40% in 1M d illite relative to protolith, whereas altered protolith in the damage zone is enriched ˜40% in illite-smectite relative to gouge and up to ˜50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/ 39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1M d) gouge illite (63±2 Ma) and illite-smectite in the damage zone (60±2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone.

  6. Thermomechanical model of hydration swelling in smectitic clays: II three-scale inter-phase mass transfer: homogenization and computational validation

    NASA Astrophysics Data System (ADS)

    Murad, Márcio A.

    1999-06-01

    In Part I a two-scale thermomechanical theory of expansive compacted clays composed of adsorbed water and clay platelets was derived using a mixture-theoretic approach and the Coleman and Noll method of exploitation of the entropy inequality. This approach led to a two-scale model which describes the interaction between thermal and hydration effects between the adsorbed water and clay minerals. The purpose of this paper is twofold. Firstly, partial results toward a three-scale model are derived by homogenizing the two-scale model for the clay particles (clusters of clay platelets and adsorbed water) with the bulk water (water next to the swelling particles). The three-scale model is of dual porosity type wherein the clay particles act as sources/sinks of water to the macroscale bulk phase flow. One of the notable consequences of the homogenization procedure is the natural derivation of a generalized inter-phase mass transfer equation between adsorbed and bulk water. Further, variational principles and finite element approximations based on the Galerkin method are proposed to discretize the two-scale model. Numerical simulations of a bentonitic clay used for engineered barrier of nuclear waste repository are performed and numerical results are presented showing the influence of physico-chemical effects on the performance of the clay buffer.

  7. Ion Exchange Resin and Clay Vitrification by Plasma Discharges

    NASA Astrophysics Data System (ADS)

    Díaz A., Laura V.; Pacheco S., Joel O.; Pacheco P., Marquidia; Monroy G., Fabiola; Emeterio H., Miguel; Ramos F., Fidel

    2006-12-01

    The lack of treatment of a low and intermediate level radioactive waste (LILRW) lead us to propose a vitrification process based on a plasma discharge; this technique incorporates LILRW into a matrix glass composed of ceramic clays material. The Mexican Institute of Nuclear Research (ININ), uses an ion exchange resin IRN 150 (styrene-divinilbence copolymer) in the TRIGA MARK III nuclear reactor. The principal objective of this resin is to absorb particles containing heavy metals and low-level radioactive particles. Once the IRN 150 resin filter capacity has been exceeded, it should be replaced and treated as LILRW. In this work, a transferred plasma system was realized to vitrify this resin taking advantage of its high power density, enthalpy and chemical reactivity as well as its rapid quenching and high operation temperatures. In order to characterize the morphological structure of these clay samples, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) techniques were applied before and after the plasma treatment.

  8. Ion Exchange Resin and Clay Vitrification by Plasma Discharges

    SciTech Connect

    Diaz A, Laura V.

    2006-12-04

    The lack of treatment of a low and intermediate level radioactive waste (LILRW) lead us to propose a vitrification process based on a plasma discharge; this technique incorporates LILRW into a matrix glass composed of ceramic clays material. The Mexican Institute of Nuclear Research (ININ), uses an ion exchange resin IRN 150 (styrene-divinilbence copolymer) in the TRIGA MARK III nuclear reactor. The principal objective of this resin is to absorb particles containing heavy metals and low-level radioactive particles. Once the IRN 150 resin filter capacity has been exceeded, it should be replaced and treated as LILRW. In this work, a transferred plasma system was realized to vitrify this resin taking advantage of its high power density, enthalpy and chemical reactivity as well as its rapid quenching and high operation temperatures. In order to characterize the morphological structure of these clay samples, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) techniques were applied before and after the plasma treatment.

  9. In situ generation of palladium nanoparticles in smectite clays

    SciTech Connect

    Kiraly, Z.; Dekany, I.; Mastalir, A.

    1996-06-01

    A novel synthetic route has been developed for the preparation of clay intercalated palladium catalysts. Liquid sorption and X-ray diffraction measurements on ethanol(1)-toluene(2)/hexadecylammonium montmorillonite dispersions indicated that a toluene-rich bulk liquid phase was equilibrated with a swollen, ethanol-rich interlamellar phase having a volume of about 0.9 cm{sup 3}/g organoclay. Introduction of palladium(II) acetate into the organoclay suspension led to the generation and deposition of a metallic palladium dispersion in the interlamellar space. This system behaved as a versatile nanophase reactor, wherein the ethanol functioned as both solvent and reducing agent. The progress of the Pd{sup 2+} {r_arrow} Pd{sup 0} reaction was monitored spectrophotometrically. The ethanolic reduction afforded Pd particles 2 to 14 nm in diameter, depending on the experimental conditions, deposited on clay particle defect sites. Organoclays loaded up to 10 mass % Pd were synthesized and characterized by BET surface area analysis, transmission electron microscopy, low-shear rheology, X-ray diffraction, and small-angle X-ray scattering measurements. The Pd-organoclay samples proved to be catalytically active in olefin hydrogenation in the liquid phase. 30 refs., 8 figs., 1 tab.

  10. Natural Radioactivity of Boron Added Clay Samples

    NASA Astrophysics Data System (ADS)

    Akkurt, I.; ćanakciı, H.; Mavi, B.; Günoǧlu, K.

    2011-12-01

    Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of diferent fields especially in dermatology application. Using clay such a field it is important to measure its natural radioacitivty. Thus the purpose of this study is to measure 226Ra, 232Th and 40K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3″×3″ NaI(Tl) detector. From the measured activity the radium equivalent activities (Raeq), external hazard index (Hex), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

  11. Stools - pale or clay-colored

    MedlinePlus

    Possible causes for clay-colored stools include: Alcoholic hepatitis Biliary cirrhosis Cancer or noncancerous (benign) tumors of the liver, biliary system, or pancreas Cysts of the bile ducts Gallstones Medications Narrowings (strictures) of the ...

  12. Polarographic reduction behaviour of clay minerals.

    PubMed

    Malik, W U; Gupta, G C

    1968-01-01

    Suspensions of the clay minerals bentonite, kaolinite illite and chlorite have been examined polarographically and reduction waves found. The differences in their behaviour, with and without the addition of surface active reagents, are reported. PMID:18960257

  13. Natural Radioactivity of Boron Added Clay Samples

    SciTech Connect

    Akkurt, I.; Guenoglu, K.; Canakcii, H.; Mavi, B.

    2011-12-26

    Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazard index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

  14. Clay-Bacteria Systems and Biofilm Production

    NASA Astrophysics Data System (ADS)

    Steiner, J.; Alimova, A.; Katz, A.; Steiner, N.; Rudolph, E.; Gottlieb, P.

    2007-12-01

    Soil clots and the aerosol transport of bacteria and spores are promoted by the formation of biofilms (bacteria cells in an extracellular polymeric matrix). Biofilms protect microorganisms by promoting adhesion to both organic and inorganic surfaces. Time series experiments on bacteria-clay suspensions demonstrate that biofilm growth is catalyzed by the presence of hectorite in minimal growth media for the studied species: Gram negatives (Pseudomonas syringae and Escherichia coli,) and Gram positives (Staphylococcus aureus and Bacillus subtilis). Soil organisms (P. syringae, B. subtilis) and organisms found in the human population (E. coli, S. aureus) are both used to demonstrate the general applicability of clay involvement. Fluorescent images of the biofilms are acquired by staining with propidium iodide, a component of the BacLightTM Live/Dead bacterial viability staining kit (Molecular Probes, Eugene, OR). The evolving polysaccharide-rich biofilm reacts with the clay interlayer site causing a complex substitution of the two-water hectorite interlayer with polysaccharide. The result is often a three-peak composite of the (001) x-ray diffraction maxima resulting from polysaccharide-expanded clays and an organic-driven contraction of a subset of the clays in the reaction medium. X-ray diffractograms reveal that the expanded set creates a broad maximum with clay subsets at 1.84 nm and 1.41 nm interlayer spacings as approximated by a least squares double Lorentzian fit, and a smaller shoulder at larger 2q, deriving from a contraction of the interlayer spacing. Washing with chlorox removes organic material from the contracted clay and creates a 1-water hectorite single peak in place of the double peak. The clay response can be used as an indirect indicator of biofilm in an environmental system.

  15. Clay-mediated reactions of HCN oligomers - The effect of the oxidation state of the clay

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Alwis, K. W.; Edelson, E. H.; Mount, N.; Hagan, W. J., Jr.

    1981-01-01

    Montmorillonite clays which contain Fe(III) inhibit the oligomerization of aqueous solutions of HCN. The inhibitory effect is due to the rapid oxidation of diaminomaleonitrile, a key intermediate in HCN oligomerization, by the Fe(III) incorporated into the aluminosilicate lattice of the clay. The Fe(III) oxidizes diaminomaleonitrile to diiminosuccinonitrile, a compound which is rapidly hydrolyzed to HCN and oxalic acid derivatives. Diaminomaleonitrile is not oxidized when Fe(III) in the montmorillonite is reduced with hydrazine. The oxidation state of the clay is an important variable in experiments designed to simulate clay catalysis on the primitive earth.

  16. Magnetic theoretical and experimental study of clays for petroleum reservoir clay typing

    NASA Astrophysics Data System (ADS)

    Ivakhnenko, Aleksandr; Makarova, Maria; Telman, Meruert

    2013-04-01

    This study describes theoretical and experimental magnetic analysis of different clay types for petroleum reservoir characterisation by using low and high field magnetic susceptibility. Most clays for example, saponite, clay loam and bentonite are paramagnetic, whereas some clays (kaolinite) and matrix minerals such as quartz and calcite are diamagnetic. Model magnetic susceptibility and magnetic hysteresis plots for various concentrations of different clays in quartz matrix were initially calculated. Experimental magnetic measurements were undertaken for comparison on a series of synthetic reservoir samples comprising various concentrations of dispersed clays in a quartz matrix. The experimental magnetic measurements showed substantial agreement with the model magnetic values, and with estimates of the magnetic susceptibility based on low and high field magnetic susceptibility for derived mineral contents. Importantly different magnetic parameters, including IRM (isothermal remnant magnetisation) were determined for the different clay types and their mixtures with the sandstone rock matrix, together with given permeability variations in the samples. Results demonstrate that these magnetic measurements potentially provide a sensitive, rapid, quantitative technique which can be used for petrophysical analysis of clay-rich rocks and clay typing.

  17. Role of clay minerals in the formation of atmospheric aggregates of Saharan dust

    NASA Astrophysics Data System (ADS)

    Cuadros, Javier; Diaz-Hernandez, José L.; Sanchez-Navas, Antonio; Garcia-Casco, Antonio

    2015-11-01

    Saharan dust can travel long distances in different directions across the Atlantic and Europe, sometimes in episodes of high dust concentration. In recent years it has been discovered that Saharan dust aerosols can aggregate into large, approximately spherical particles of up to 100 μm generated within raindrops that then evaporate, so that the aggregate deposition takes place most times in dry conditions. These aerosol aggregates are an interesting phenomenon resulting from the interaction of mineral aerosols and atmospheric conditions. They have been termed "iberulites" due to their discovery and description from aerosol deposits in the Iberian Peninsula. Here, these aggregates are further investigated, in particular the role of the clay minerals in the aggregation process of aerosol particles. Iberulites, and common aerosol particles for reference, were studied from the following periods or single dust events and locations: June 1998 in Tenerife, Canary Islands; June 2001 to August 2002, Granada, Spain; 13-20 August 2012, Granada; and 1-6 June 2014, Granada. Their mineralogy, chemistry and texture were analysed using X-ray diffraction, electron microprobe analysis, SEM and TEM. The mineral composition and structure of the iberulites consists of quartz, carbonate and feldspar grains surrounded by a matrix of clay minerals (illite, smectite and kaolinite) that also surrounds the entire aggregate. Minor phases, also distributed homogenously within the iberulites, are sulfates and Fe oxides. Clays are apparently more abundant in the iberulites than in the total aerosol deposit, suggesting that iberulite formation concentrates clays. Details of the structure and composition of iberulites differ from descriptions of previous samples, which indicates dependence on dust sources and atmospheric conditions, possibly including anthropic activity. Iberulites are formed by coalescence of aerosol mineral particles captured by precursor water droplets. The concentration of

  18. What Makes a Natural Clay Antibacterial?

    PubMed Central

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-Peterson, Amisha T.

    2011-01-01

    Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (<200 nm), illite-smectite and reduced iron phases. The role of clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals. PMID:21413758

  19. Relationship between heavy metal contents and clay mineral properties in surface sediments: Implications for metal pollution assessment

    NASA Astrophysics Data System (ADS)

    Chen, Yueh-Min; Gao, Jin-bo; Yuan, Yong-Qiang; Ma, Jun; Yu, Shen

    2016-08-01

    Clay minerals in surface sediments can affect the adsorption of heavy metals. However, few historical studies have focused on the influence of fine clay mineral characteristics on metal sorption. Since the reactions between heavy metals and fine clay minerals in sediments remain obscure, this study investigates the influence of fine clay mineral characteristics on metal sorption in a typical urbanizing small watershed. Clay minerals, including nanoparticles with various size fractions ranging from 1000 to 2000 (clay), 450-1000 (fine clay), and 220-450 (very fine clay) nm were used to demonstrate their transformation from well crystalline to poorly crystalline. The nanoparticles were collected and evaluated by determination of their surface area, X-ray diffraction, scanning electron microscopy (SEM) and chemical analyses. The relationship between metal content and properties of the surface sediments was also revealed by canonical correlation analysis. With smaller particle sizes, nanoparticles (very fine clay) were observed to be poorly crystalline, possibly indicating few repetitions of unit cells as a result of preferential structural disruption of other crystal planes caused by pressure-induced phase transition in the fine-size fractions. The first canonical matrix (M) variables of metal contents can be predicted by both surface area and pore volume, followed by kaolinite and illite contents. On the other hand, the category of metal, i.e., Cu, Cr, Zn, or Pb, was significantly correlated with the first 'M' canonical variables. The data obtained in the present study are of fundamental significance in advancing our understanding of the reactions between heavy metals and fine clay minerals in the terrestrial ecosystem.

  20. Stress-Induced Permeability Anisotropy of Resedimented Boston Blue Clay

    NASA Astrophysics Data System (ADS)

    Adams, A. L.; Germaine, J. T.; Flemings, P. B.

    2011-12-01

    Significant permeability anisotropy, defined as the ratio of horizontal to vertical permeability, can develop in a homogenous material due to one dimensional compression. In Resedimented Boston Blue Clay (RBBC), a low plasticity glacio-marine illitic clay, the permeability anisotropy increases from 1.22 to 1.85 as the porosity decreases from 0.5 to 0.37. The permeability decreases by greater than one order of magnitude over this porosity range, ranging from 7.5 x 10-17 m2 to 3.9 x 10-18 m2 vertically and from 9.1 x 10-17 m2 to 7.2 x 10-18 m2 horizontally. SEM images, taken at different orientations and stress levels, reveal that pores become increasingly elongate perpendicular to the maximum (vertical) loading direction as stress is increased. We interpret that rotation of platy materials creates this fabric. To make these measurements, a new method to measure the permeability anisotropy using cubic specimens was developed. In addition, we correct for test sequence bias and minimize scatter in the data set to produce a well defined permeability anisotropy vs. porosity trend. A better understanding of the evolution of permeability anisotropy during sediment burial is important for understanding a range of transport processes in the subsurface.

  1. A clay grouting technique for granitic rock adjacent to clay bulkhead

    NASA Astrophysics Data System (ADS)

    Masumoto, K.; Sugita, Y.; Fujita, T.; Martino, J. B.; Kozak, E. T.; Dixon, D. A.

    Excavation and re-distribution of the stress around the tunnel lead to the development of an excavation damage zone (EDZ). While the bulkheads are keyed into the rock wall of the tunnel to act as cut-offs for the EDZ of the tunnel, clay grouting was conducted around the clay bulkhead as an additional measure to interrupt the connectivity of EDZ at the bulkhead. Clay grouting is being tested to determine if it is an effective method to reduce the permeability of fractured rock. The grouting into the EDZ is difficult because many of the fractures in the EDZ are connected with the excavation surface and cannot be filled efficiently by pressurizing the grout slurry. Therefore, the in situ injection tests of the clay grouting technique for the EDZ adjacent to the clay bulkhead were conducted to demonstrate the clay grouting technique and to estimate the ability of clay grouting to reduce permeability in the EDZ. This paper presents the results of these tests. Three in situ tests of clay grouting were performed during the Tunnel Sealing Experiment (TSX), conducted at Canada’s Underground Research Laboratory (URL) in the granitic rock to demonstrate technologies for tunnel sealing at full-scale. First, a clay grouting trial was conducted at a trial key in the tunnel about 25 m above the TSX tunnel. Secondly, the two series of clay grouting were performed in the TSX tunnel, on the upstream face of the key prior to the installation of the seal material of the clay key and later on the downstream side of the bulkhead. The results of these tests indicated a reduction in the permeability of granitic rock around the holes after grouting.

  2. Electrically Insulative Performances of Ceramic and Clay Films Deposited via Supersonic Spraying

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Gun; Kim, Do-Yeon; Joshi, Bhavana N.; Lee, Jong-Hyuk; Lee, Tae-Kyu; Kim, Jang-soo; Yang, Dae-ho; Kim, Woo-Young; Al-Deyab, Salem S.; Yoon, Sam S.

    2016-04-01

    Supersonic spray coating techniques were applied to deposit ceramic and clay particles as films for use in electrical insulation. TiO2 and Al2O3 ceramics were aerosol-deposited under vacuum while kaolinite, montmorillonite, and bentonite clays were deposited by cold spraying in open air. The electrical resistivity of Al2O3 and TiO2 were ~109 and ~108 Ω cm, respectively. The resistivity of kaolinite and montmorillonite were ~1012 Ω cm. Bentonite showed the lowest electrical resistivity of ~109 Ω cm among the clays because of the high cation exchange capacity of the material. The film surface morphologies and mechanical properties in the form of hardness and scratchability were also investigated.

  3. Parametric studies on effective elastic modulus of nano-clay/polymer composites

    NASA Astrophysics Data System (ADS)

    Thakur, Arvind Kumar; Srinivas, J.

    2016-04-01

    This paper proposes a methodology of finding effective elastic properties of nanoclay-reinforced polymer composites with aligned clay particles. When interphase regions exist between nanoclay platelets and polymer, numerical homogenization is initially required to identify the properties of effective particle consisting of both clay and interface regions. Once the elastic properties of equivalent particle are obtained, Mori-Tanaka approach is employed to identify all the effective properties of resultant composite. The methodology is implemented with a modular based computer program developed in MATLAB and the variation of longitudinal modulus as a function of weight fraction of nanoclay, aspect ratio of fibers, number of stacks, nanoclay volume fraction etc is reported. The empirical results are validated with a numerical model developed in ANSYS using a representative volume element for prediction of the elastic modulus. Results are illustrated with two cases of exfoliated morphology.

  4. Distinguishing black carbon from biogenic humic substances in soil clay fractions

    USGS Publications Warehouse

    Laird, D.A.; Chappell, M.A.; Martens, D.A.; Wershaw, R. L.; Thompson, M.

    2008-01-01

    Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2-2.0????m e.s.d.), medium (0.02-0.2????m e.s.d.), and fine (> 0.02????m e.s.d.) clay subfractions from three Midwestern soils and characterized the organic material associated with these subfractions using 13C-CPMAS-NMR, DTG, SEM-EDX, incubations, and radiocarbon age. Most of the C in the coarse clay subfraction was present as discrete particles (0.2-5????m as seen in SEM images) of black carbon (BC) and consisted of approximately 60% aromatic C, with the remainder being a mixture of aliphatic, anomeric and carboxylic C. We hypothesize that BC particles were originally charcoal formed during prairie fires. As the BC particles aged in soil their surfaces were oxidized to form carboxylic groups and anomeric and aliphatic C accumulated in the BC particles either by adsorption of dissolved biogenic compounds from the soil solution or by direct deposition of biogenic materials from microbes living within the BC particles. The biogenic soil organic matter was physically separated with the medium and fine clay subfractions and was dominated by aliphatic, anomeric, and carboxylic C. The results indicate that the biogenic humic materials in our soils have little aromatic C, which is inconsistent with the traditional heteropolymer model of humic substances.

  5. Structure-Property Correlation in Iron Oxide Nanoparticle-Clay Hybrid Materials

    SciTech Connect

    Son, You-Hwan; Lee, Jung-Kun; Soong, Yee; Martello, Donald; Chyu, Minking

    2010-03-16

    Heterostructures between montmorillonite and embedded alpha-Fe2O3 nanoparticles are explored to create new hybrid particles with high magnetic response and magnetic-field induced tunability. α-Fe2O3 nanoparticles are hybridized to montmorillonite clays by using an intercalation technique. Also, stable aqueous fluids consisting of the heterostructured particles are prepared and the rheology of the fluids under external magnetic field is examined. When α-Fe2O3 a nanoparticles are embedded in the interlayer space of montmorillonite clays, the magnetization per Fe atom increases at most 60 times. This unique combination of the magnetization and the coercivity is traced to the suppressed growth of embedded α-Fe2O3 nanoparticles by the aluminosilicate layers, leading to the size control, anisotropic magnetic interaction, and uniaxial stress of two-dimensionally distributed α-Fe2O3 nanoparticles. Furthermore, high magnetization of heterostructured particles leads to strong dependence of fluids' viscosity on the external magnetic field. The present study indicates that the new heterostructured particles have unique magnetic fielddependent properties that are not attainable in individual clay or iron oxide particles.

  6. Natural ferrihydrite as an agent for reducing turbidity caused by suspended clays.

    PubMed

    Rhoton, F E; Bigham, J M

    2009-01-01

    Biologically impaired waters are often caused by the turbidity associated with elevated suspended sediment concentrations. Turbidity can be reduced by the addition of positively charged compounds that coagulate negatively charged particles in suspension, causing them to flocculate. This research was conducted to determine the effectiveness of ferrihydrite, a poorly crystalline Fe oxide, as a flocculating agent for suspended clays similar to those found in high-turbidity waters of the Mississippi delta. Clay concentrations of 100 mg L(-1) from a Dubbs silt loam (fine silty, mixed, active, thermic Typic Hapludalfs), a Forestdale silty clay loam (fine, smectitic, thermic Typic Hapludalfs), and a Sharkey clay (very fine, smectitic, thermic Chromic Epiaquerts) were suspended in 0.0005 mol L(-1) CaCl(2) solutions at pH 5, 6, 7, or 8. Natural ferrihydrite with a zero point of charge at pH 5.8 was acquired from a drinking water treatment facility and mixed with the suspension at concentrations of 0, 10, 25, and 50 mg L(-1). After settling periods of 24 and 48 h, percent transmittance was measured at a wavelength of 420 nm using a 3-mL sample collected at a depth of 2 cm. The greatest reductions in turbidity after 24-h equilibration were recorded for the pH 5 suspensions of the Dubbs (31%) and Forestdale (37%) clays at a ferrihydrite concentration of 10 mg L(-1) and for the Sharkey clay at a ferrihydrite concentration of 25 mg L(-1) (relative to the 0 ferrihydrite treatment). Water clarity for all samples further increased after 48 h. These results indicate that the effectiveness of ferrihydrite, as a means of reducing turbidity associated with suspended clays, is greatest at pH values below its zero point of charge. PMID:19643754

  7. HDS and deep HDS activity of Co/Mo/S-mesostructured synthetic clays.

    SciTech Connect

    Carrado, K. A.; Song, C.; Kim, J. H.; Castagnola, N.; Fernandez-Saavedra, R.; Marshall, C. L.; Schwartz, M. M.; Penn State Univ.; ICMM-CSIC

    2006-01-01

    The goal of this work is to identify more promising supports from synthetic clay materials to advance hydrotreating catalyst development. Silica sol can be used as the silicon-containing starting material when creating nanoporous layered silicate catalysts with a certain portion of unreacted sol particles incorporated into the final matrix. The resulting structure then has mesoporosity and a unique morphology. Hectorite-based clays have been prepared using different silica sols in order to ascertain the importance of sol characteristics on the final matrix. Several techniques have been applied to characterize the materials, including XRD, TGA, N2 porosimetry, and TEM. For hydrodesulfurization (HDS), the conversion of dibenzothiophene (DBT) to biphenyl was examined at 400 degrees C using CoMoS-loaded mesostructured clay supports. No hydrogenation or hydrocracking was observed with any of the clay supports. The most active clay was derived from Ludox silica sol AS-30 with an activity of 65% DBT conversion and 100% selectivity to biphenyl (BP). For comparison, a reference commercial catalyst displayed 94% BP selectivity. For deep HDS, the conversion of 4,6-dimethyldibenzothiophene was tested at 325 and 350 degrees C. At 325 degrees C, conversions are 92% of commercial catalysts for a CoMoS-loaded mesostructured clay derived from Ludox AM-30 silica sol. A commercially available synthetic hectorite called laponite has very low activity, indicating that the unique morphology of the mesostructured clays is important. Hydrogenolysis vs. hydrogenation pathways are compared for the deep HDS reaction. HR-TEM of the most active deep HDS catalyst revealed a multilayered MoS2 morphology.

  8. Aggregation and stability of anisotropic charged clay colloids in aqueous medium in the presence of salt.

    PubMed

    Ali, Samim; Bandyopadhyay, Ranjini

    2016-01-01

    Na-montmorillonite nanoclay is a colloid of layered mineral silicate. When dispersed in water, this mineral swells on absorption of water and exfoliates into platelets with electric double layers on their surfaces. Even at low particle concentration, the aqueous dispersion can exhibit a spontaneous ergodicity breaking phase transition from a free flowing liquid to nonequilibrium, kinetically arrested and disordered states such as gels and glasses. In an earlier publication [Applied Clay Science, 2015, 114, 8592], we showed that the stability of clay gels can be enhanced by adding a salt later to the clay dispersion prepared in deionized water, rather than by adding the clay mineral to a previously mixed salt solution. Here, we directly track the collapsing interface of sedimenting clay gels using an optical method and show that adding salt after dispersing the clay mineral does indeed result in more stable gels even in very dilute dispersions. These weak gels are seen to exhibit a transient collapse after a finite delay time, a phenomenon observed previously in depletion gels. The velocity of the collapse oscillates with the age of the sample. However, the average velocity of collapse increases with sample age up to a peak value before decreasing at higher ages. With increasing salt concentration, the delay time for transient collapse decreases, while the peak value of the collapsing velocity increases. Using ultrasound attenuation spectroscopy, rheometry and cryogenic scanning electron microscopy, we confirm that morphological changes of the gel network assembly, facilitated by thermal fluctuations, lead to the observed collapse phenomenon. Since clay minerals are used extensively in polymer nanocomposites, as rheological modifiers, stabilizers and gas absorbents, we believe that the results reported in this work are extremely useful for several practical applications and also for understanding geophysical phenomena such as the formation and stability of quicksand

  9. Modeling near-infrared reflectance spectra of clay and sulfate mixtures and implications for Mars

    NASA Astrophysics Data System (ADS)

    Stack, K. M.; Milliken, R. E.

    2015-04-01

    High-resolution mapping by visible and near-infrared orbital spectrometers has revealed a diversity of hydrated mineral deposits on the surface of Mars. Quantitative analysis of mineral abundances within these deposits has the potential to distinguish depositional and diagenetic processes. Such analysis can also provide important constraints on the nature of putative global and local-scale mineralogical transitions on Mars. However, the ability of models to extract quantitative mineral abundances from spectra of mixtures relevant to sedimentary rocks remains largely untested. This is particularly true for clay and sulfate minerals, which often occur as fine-grained components of terrestrial sedimentary rocks and are known to occur in a number of sedimentary deposits on Mars. This study examines the spectral properties of a suite of mixtures containing the Mg-sulfate epsomite mixed with varying proportions of smectitic clay (saponite, nontronite, and montmorrilonite). The goal of this work is to test the ability of checkerboard (linear) and intimate (non-linear) mixing models to obtain accurate estimates of mineral abundances under ideal and controlled laboratory conditions. The results of this work suggest that: (1) spectra of clay-sulfate mixtures can be reproduced by checkerboard and intimate mixing models to within 2% absolute reflectance or single scattering albedo, (2) clay and epsomite abundance can be modeled to within 5 wt.% when particle diameter is optimized, and (3) the lower threshold for modeling clay in spectra of clay-epsomite mixtures is approximately 10 wt.%, below which the models often fail to recognize the presence of clay.

  10. Clay Minerals are controlled by the environment - Clay Minerals control the environment

    NASA Astrophysics Data System (ADS)

    Stahr, K.; Zarei, M.

    2012-04-01

    Where clay minerals are analyzed in soils, often there is some confusion, because in the widespread loess-affected and moraine landscapes of Europe quite a variety of clay minerals is found. The sources of these minerals are inherited from the local solid rock, transported through different processes, transformed through mineral changes and inherited from paleo-environments. Very often a miserable assemblage in the clay fraction is found with mica clay, smectite, kaolinite, chlorite and also some quartz. In order to understand the current dynamic of clay mineral formation, very detailed and quantitative analysis in comparison of horizons and landscape are necessary. It is much easier to through light on the development, if conditions are looked for where a single specific mineral can be formed like short range order minerals from volcanic ashes or smectites from basaltic parent material. Old leaching land surfaces will form kaolinitic and in tropical areas gibbsitic clay fractions. In arid environments of deserts and desert fringes, palygorskite and sepiolite can dominate. In general, clay minerals buffer the environment. This is mainly due to the extraordinary large interfaces between mineral surface and pore systems. In the last years mainly the processes of buffering through charging soil solution and of buffering through mineral organic compounds have been analyzed. Development of new microscopic and spectromethods have brought great progress in understanding the role of clays in soil environments.

  11. Clay mineralogy of weathering rinds and possible implications concerning the sources of clay minerals in soils.

    USGS Publications Warehouse

    Colman, Steven M.

    1982-01-01

    Weathering rinds on volcanic clasts in Quaternary deposits in the western US contain only very fine-grained and poorly crystalline clay minerals. Rinds were sampled from soils containing well-developed argillic B horizons in deposits approx 105 yr old or more. The clay-size fraction of the rinds is dominated by allophane and iron hydroxy-oxides, whereas the B horizons contain abundant well-crystallized clay minerals. The contrast between the clay mineralogy of the weathering rinds, in which weathering is isolated from other soil processes, and that of the associated soil matrices suggests a need to reassess assumptions concerning the rates at which clay minerals form and the sources of clay minerals in argillic B horizons. It seems that crystalline clay minerals form more slowly in weathering rinds than is generally assumed for soil environments and that the weathering of primary minerals may not be the dominant source of crystalline clay minerals in Middle to Late Pleistocene soil.-A.P.

  12. Magnetic anisotropy, scanning electron microscopy, and X ray pole figure goniometry study of inclination shallowing in a compacting clay-rich sediment

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.

    1992-12-01

    Anisotropy of anhysteretic remanence (AAR), scanning electron microscopy (SEM), and X ray pole figure goniometry studies of clay-rich sediments were conducted to delineate the interactions between magnetite and clay particles which cause inclination shallowing during compaction. These studies used synthetic sediments composed of kaolinite or illite and two grain sizes of mgnetite, 0.45 μm and 2-3 μm. Natural marine sediments which contained 40-50% clay were also used. The sediments were compacted by pressures as high as 0.157 MPa. The sediments' porosity decrease suggests that the compaction experiments model burial depths up to 400-500 m. The main result of this study is that inclination shallowing and void ratio versus pressure curves show two points where behavior changes. A rapid decrease in inclination and void ratio occurs up to a pressure of 0.02 MPa. This is accompanied by a magnetic intensity decrease of 20-30%. Compaction at pressures between 0.02 MPa and 0.05 MPa causes a further decrease in these parameters at moderate rates, while compaction at pressures above 0.05 MPa causes very little change. Percent magnetic anisotropy and X ray pole figure intensity ratio versus pressure curves show only one point where behavior changes at 0.05 MPa with a rapid increase at lower pressures and little change at higher pressures. A model to explain this behavior, based on the SEM obsevations as well as the magnetic anisotropy, pole figure, and inclination data, suggests that compaction up to 0.02 MPa causes a decrease in pore volume with little reorientation of clay particles. Some magnetic particles are firmly attached to clay particles, whereas other loosely attached particles are either randomized or subvertical ones are preferentially disturbed causing inclination shallowing and an intensity decrease. At pressures between 0.02 MPa and 0.05 MPa, magnetite particles have become firmly attached to clay particles and start to follow the reorientation of clay

  13. Comparison of Floc Growth and Stability in Four Estuarine Clay Simulations

    NASA Astrophysics Data System (ADS)

    Reed, A. H.; Smith, J. P.; Gurzynski, W.; Zhang, G.

    2014-12-01

    Flocculated sediment transport is a primary determinant of hydrodynamics and geomorphology in many muddy nearshore environments which contain significant amounts of clay. In these nearshore and estuarine environments, as in most oceanic environments, the clay mineral occurrence is dominated by the following: montmorillonite (2:1 expandable), illite (2:1 non-expandable) and kaolinite (1:1 non-expandable). However, the percentages of clay minerals within these environments vary significantly. This work addresses the importance of clay mineral percentages on floc growth rates and stability. A series of analyses used four different ratios of montmorillonite, illite and kaolinite; these ratios serve to simulate the clay mineral assemblage in four different rivers. The clay minerals were mixed into saline water within which guar, a nonionic biopolymer, had previously been dissolved. Upon addition, the mixture was shaken vigorously for several minutes and then the system was allowed to settle into a quiescent environment. Flocs were maintained in a quiescent, no-flow environment until analyzed. The analyses consisted of subjecting the flocs to three flow rates within a flow through particle size analyzer, CILAS1190. For each flow rate, floc sizes were quantified and stability was inferred from changes in floc size. The flocs were analyzed during a two month period; assessments were made after 1d, 2d, 7d, 14d, 1m and 2m from the initial mixing. Results indicate that while floc size increased significantly over time, total floc stability changed less significantly. This work suggests that floc growth and stability may be achieved in a relatively short duration of time within quiescent environments. The importance of hydrodynamic stress on floc size and stability will be an important aspect for future research; subjecting flocs to hydrodynamic stress will address the importance of particle collisions and fluid-induced stress on floc size and stability.

  14. Clay mineralogy of surface sediments as a tool for deciphering river contributions to the Cariaco Basin (Venezuela)

    NASA Astrophysics Data System (ADS)

    Bout-Roumazeilles, V.; Riboulleau, A.; ChâTelet, E. Armynot; Lorenzoni, L.; Tribovillard, N.; Murray, R. W.; Müller-Karger, F.; Astor, Y. M.

    2013-02-01

    The mineralogical composition of 95 surface sediment samples from the Cariaco Basin continental shelf and Orinoco delta was investigated in order to constrain the clay-mineral main provenance and distribution within the Cariaco Basin. The spatial variability of the data set was studied using a geo-statistical approach that allows drawing representative clay-mineral distribution maps. These maps are used to identify present-day dominant sources for each clay-mineral species in agreement with the geological characteristics of the main river watersheds emptying into the basin. This approach allows (1) identifying the most distinctive clay-mineral species/ratios that determine particle provenance, (2) evaluating the respective contribution of local rivers, and (3) confirming the minimal present-day influence of the Orinoco plume on the Cariaco Basin sedimentation. The Tuy, Unare, and Neveri Rivers are the main sources of clay particles to the Cariaco Basin sedimentation. At present, the Tuy River is the main contributor of illite to the western part of the southern Cariaco Basin continental shelf. The Unare River plume, carrying smectite and kaolinite, has a wide westward propagation, whereas the Neveri River contribution is less extended, providing kaolinite and illite toward the eastern Cariaco Basin. The Manzanares, Araya, Tortuga, and Margarita areas are secondary sources of local influence. These insights shed light on the origin of present-day terrigenous sediments of the Cariaco Basin and help to propose alternative explanations for the temporal variability of clay mineralogy observed in previously published studies.

  15. Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

    SciTech Connect

    Randall T. Cygan

    2007-06-01

    “Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

  16. Biodegradation of pyrene in sand, silt and clay fractions of sediment.

    PubMed

    Cui, Xinyi; Hunter, Wesley; Yang, Yu; Chen, Yingxu; Gan, Jay

    2011-04-01

    Microbial degradation is the dominant pathway for natural attenuation of PAHs in environmental compartments such as sediments, which in turn depends on the bioavailability of PAHs. The bioavailability of PAHs has seldom been studied at the sediment particle size scale. We evaluated biodegradation of pyrene by Mycobacterium vanbaalenii PYR-1 as a function of sediment particle sizes, and investigated the relationship between the rate of degradation on sand, silt and clay particles with their individual desorption kinetics measured with the Tenax extraction method. Regression analysis showed that the total organic carbon (TOC), black carbon (BC), and specific surface area (SSA) of the specific particle size fractions, instead of the particle size scale itself, were closely related (P<0.01) with the mineralization rate. While the fraction in the rapid desorption pool (F (rapid)) ranged from 0.11 to 0.38 for the whole sediments and different size groups, the fractions mineralized after 336-h incubation (0.52 to 0.72) greatly surpassed the F (rapid) values, suggesting utilization of pyrene in the slow desorption pool (F (slow)). A biodegradation model was modified by imbedding a two-phase desorption relationship describing sequential Tenax extractions. Model analysis showed that pyrene sorbed on silt and clay aggregates was directly utilized by the degrading bacteria. The enhanced bioavailability may be attributed to the higher chemical concentration, higher TOC or larger SSA in the silt and clay fractions, which appeared to overcome the reduced bioavailability of pyrene due to sorption, making pyrene on the silt and clay particles readily available to degrading microbes. This conjecture merits further investigation. PMID:20714921

  17. Effect of the solvent on the size of clay nanoparticles in solution as determined using an ultraviolet-visible (UV-Vis) spectroscopy methodology.

    PubMed

    Alin, Jonas; Rubino, Maria; Auras, Rafael

    2015-06-01

    Ultraviolet-visible (UV-Vis) spectroscopy methodology was developed and utilized for the in situ nanoscale measurement of the size of mineral clay agglomerates in various liquid suspensions. The clays studied were organomodified and unmodified montmorillonite clays (I.44p, Cloisite 93a, and PGN). The methodology was compared and validated against dynamic light scattering (DLS) analysis. The method was able to measure clay agglomerates in solvents in situations where DLS analysis was unsuccessful due to the shapes, polydispersity, and high aspect ratios of the clay particles and the complexity of the aggregates, or dispersion medium. The measured clay agglomerates in suspension were found to be in the nanometer range in the more compatible solvents, and their sizes correlated with the Hansen solubility parameter space distance between the clay modifiers and the solvents. Mass detection limits for size determination were in the range from 1 to 9 mg/L. The methodology thus provides simple, rapid, and inexpensive characterization of clays or particles in the nano- or microsize range in low concentrations in various liquid media, including complex mixtures or highly viscous fluids that are difficult to analyze with DLS. In addition, by combining UV-VIS spectroscopy with DLS it was possible to discern flocculation behavior in liquids, which otherwise could result in false size measurements by DLS alone. PMID:25955412

  18. Chemistry and mineralogy of clay minerals in Asian and Saharan dusts and the implications for iron supply to the oceans

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Achterberg, E. P.

    2014-11-01

    Mineral dust supplied to remote ocean regions stimulates phytoplankton growth through delivery of micronutrients, notably iron (Fe). Although attention is usually paid to Fe (hydr)oxides as major sources of available Fe, Fe-bearing clay minerals are typically the dominant phase in mineral dust. The mineralogy and chemistry of clay minerals in dust particles, however, are largely unknown. We conducted microscopic identification and chemical analysis of the clay minerals in Asian and Saharan dust particles. Cross-sectional slices of dust particles were prepared by focused ion beam (FIB) techniques and analyzed by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS). TEM images of FIB slices revealed that clay minerals occurred as either nano-thin platelets or relatively thick plates. Chemical compositions and lattice fringes of the nano-thin platelets suggested that they included illite, smectite, illite-smectite mixed layers, and their nanoscale mixtures (illite-smectite series clay minerals, ISCMs) which could not be resolved with an electron microbeam. EDXS chemical analysis of the clay mineral grains revealed that the average Fe content was 5.8% in nano-thin ISCM platelets assuming 14% H2O, while the Fe content of illite and chlorite was 2.8 and 14.8%, respectively. In addition, TEM and EDXS analyses were performed on clay mineral grains dispersed and loaded on micro-grids. The average Fe content of clay mineral grains was 6.7 and 5.4% in Asian and Saharan dusts, respectively. A comparative X-ray diffraction analysis of bulk dusts showed that Saharan dust was more enriched in clay minerals than Asian dust, while Asian dust was more enriched in chlorite. Clay minerals, in particular nanocrystalline ISCMs and Fe-rich chlorite, are probably important sources of Fe to remote marine ecosystems. Further detailed analyses of the mineralogy and chemistry of clay minerals in global mineral dusts are required to evaluate the

  19. Organic or organometallic template mediated clay synthesis

    SciTech Connect

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1992-12-31

    A method is given for incorporating diverse varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and LiF for 2 days with an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by US patent No. 3,887,454 issued to Hickson, June 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have water-solubility, positive charge, and thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  20. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1994-05-03

    A method is described for incorporating diverse varieties of intercalates or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalate or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalates or templates may be introduced. The intercalates or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays. 22 figures.

  1. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

    1994-01-01

    A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  2. Strong orientational coordinates and orientational order parameters for symmetric objects

    NASA Astrophysics Data System (ADS)

    Haji-Akbari, Amir; Glotzer, Sharon C.

    2015-12-01

    Recent advancements in the synthesis of anisotropic macromolecules and nanoparticles have spurred an immense interest in theoretical and computational studies of self-assembly. The cornerstone of such studies is the role of shape in self-assembly and in inducing complex order. The problem of identifying different types of order that can emerge in such systems can, however, be challenging. Here, we revisit the problem of quantifying orientational order in systems of building blocks with non-trivial rotational symmetries. We first propose a systematic way of constructing orientational coordinates for such symmetric building blocks. We call the arising tensorial coordinates strong orientational coordinates (SOCs) as they fully and exclusively specify the orientation of a symmetric object. We then use SOCs to describe and quantify local and global orientational order, and spatiotemporal orientational correlations in systems of symmetric building blocks. The SOCs and the orientational order parameters developed in this work are not only useful in performing and analyzing computer simulations of symmetric molecules or particles, but can also be utilized for the efficient storage of rotational information in long trajectories of evolving many-body systems.

  3. Effect of Water on Elastic and Creep Properties of Self-Standing Clay Films.

    PubMed

    Carrier, Benoit; Vandamme, Matthieu; Pellenq, Roland J-M; Bornert, Michel; Ferrage, Eric; Hubert, Fabien; Van Damme, Henri

    2016-02-01

    We characterized experimentally the elastic and creep properties of thin self-standing clay films, and how their mechanical properties evolved with relative humidity and water content. The films were made of clay montmorillonite SWy-2, obtained by evaporation of a clay suspension. Three types of films were manufactured, which differed by their interlayer cation: sodium, calcium, or a mixture of sodium with calcium. The orientational order of the films was characterized by X-ray diffractometry. The films were mechanically solicited in tension, the resulting strains being measured by digital image correlation. We measured the Young's modulus and the creep over a variety of relative humidities, on a full cycle of adsorption-desorption for what concerns the Young's modulus. Increasing relative humidity made the films less stiff and made them creep more. Both the elastic and creep properties depended significantly on the interlayer cation. For the Young's modulus, this dependence must originate from a scale greater than the scale of the clay layer. Also, hysteresis disappeared when plotting the Young's modulus versus water content instead of relative humidity. Independent of interlayer cation and of relative humidity greater than 60%, after a transient period, the creep of the films was always a logarithmic function of time. The experimental data gathered on these mesoscale systems can be of value for modelers who aim at predicting the mechanical behavior of clay-based materials (e.g., shales) at the engineering macroscopic scale from the one at the atomistic scale, for them to validate the first steps of their upscaling scheme. They provide also valuable reference data for bioinspired clay-based hybrid materials. PMID:26752345

  4. Genesis of clay mineral assemblages and micropaleoclimatic implications in the Tertiary Powder River Basin, Wyoming

    SciTech Connect

    Flores, R.M.; Weaver, J.N. ); Bossiroy, D.; Thorez, J. )

    1990-05-01

    An x-ray diffraction (XRD) study was undertaken on the clay mineralogy of the early Tertiary coal-bearing sequences of the Powder River basin. The vertical and lateral distribution of alternating fluvial conglomerates, sandstones, mudstones, shales, coals, and paleosols reveals a transition from alluvial fans along the basin margin to an alluvial plain and peat bogs basinward. Samples included unweathered shales and mudstones from a borehole and a variety of corresponding surface outcrop samples of Cambrian to Eocene age. Samples older than Tertiary were collected along the basin margin specifically to determine the potential source of parent material during Tertiary sedimentation. XRD analyses were performed on the <2-{mu}m fraction prepared as oriented aggregates. To investigate the materials in their natural state, no chemical pre-treatments the authors applied before the analysis. A series of specific post-treatments, consisting of catonic saturation (Li+, K+), a solution with polyalcohols, heating, acid attack and hydrazine saturation was selectively applied. These post-treatments permit a good discrimination between the mimetic clay minerals such as smectite and illite-smectite mixed layers that constitute the bulk of the clay fraction in the Tertiary rocks. When analyzed only using routine XRD, these swelling minerals are apparently uniformly distributed in the fluvial sedimentary rocks and are better interpreted as a single smectitic population. However, the post-treatments clearly differentiate both qualitatively and quantitatively this smectitic stock. Other clays include illite and kaolinite, which have different degrees of crystallinity, and minor interstratified clays (i.e., illite-chlorite, chlorite-smectite). The clay minerals in pre-Tertiary (and pedogenic) materials are different from those in the Tertiary rocks.

  5. Mineral Acquisition from Clay by Budongo Forest Chimpanzees

    PubMed Central

    Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms. PMID:26218593

  6. Decomposition of organochlorine compounds in flue gas from municipal solid waste incinerators using natural and activated acid clays.

    PubMed

    Hwang, In-Hee; Takahashi, Shigetoshi; Matsuo, Takayuki; Matsuto, Toshihiko

    2014-09-01

    High-temperature particle control (HTPC) using a ceramic filter is a dust collection method without inefficient cooling and reheating of flue gas treatment; thus, its use is expected to improve the energy recovery efficiency of municipal solid waste incinerators (MSWIs). However there are concerns regarding de novo synthesis and a decrease in the adsorptive removal efficiency of dioxins (DXNs) at approximately 300 degrees C. In this study, the effect of natural and activated acid clays on the decomposition of monochlorobenzene (MCB), one of the organochlorine compounds in MSW flue gas, was investigated. From the results of MCB removal tests at 30-300 degrees C, the clays were classified as adsorption, decomposition, and low removal types. More than half of the clays (four kinds of natural acid clays and two kinds of activated acid clays) were of the decomposition type. In addition, the presence of Cl atoms detached from MCB was confirmed by washing the clay used in the MCB removal test at 300 degrees C. Activated acid clay was expected to have high dechlorination performance because of its proton-rich-composition, but only two clays were classed as decomposition type. Conversely, all the natural acid clays used in this work were of the decomposition type, which contained relatively higher di- and trivalent metal oxides such as Al2O3, Fe2O3, MgO, and CaO. These metal oxides might contribute to the catalytic dechlorination of MCB at 300 degrees C. Therefore, natural and activated acid clays can be used as alternatives for activated carbon at 300 degrees C to remove organochloride compounds such as DXNs. Their utilization is expected to mitigate the latent risks related to the adoption of HTPC, and also to contribute to the improvement of energy recovery efficiency of MSWI. Implications: The effect of natural and activated acid clays on MCB decomposition was investigated to evaluate their suitability as materials for the removal of organochlorine compounds, such as

  7. Development of laboratory and process sensors to monitor particle size distribution of industrial slurries (including shape characterization). Final technical report

    SciTech Connect

    Pendse, H.P.; Goetz, P.J.; Sharma, A.; Han, W; Bliss, T.C.

    1996-10-01

    The overall goal of the Particle Size Distribution (PSD) sensor projects was to develop and commercialize a sensor system capable of particle analysis, in terms of size distributions, using concentrated suspensions at high solids concentrations. The early research was focused on application of ultrasonic spectroscopy of inorganic pigment slurries (e.g. titanium dioxide) commonly encountered on paper industry. During the project prototypes were tested in both academic and industrial laboratories. Work also involved successful field tests of the on-line prototype at a pigment manufacturing facility. Pen Kem continued the work at its cost beyond the initial funded period from March `92 to September `94. The first project (DE- FC05-88CE40684), which began in September 1988, culminated in a commercial laboratory instrument, Pen Kem AcoustoPhor {trademark} 8000, put on the market in June 1993. The follow-on project was aimed at investigation of shape and orientation effects on ultrasonic spectroscopy. A new cooperative agreement was awarded in September 1994 (DE-FC05-94CE40005) to develop shape characterization capabilities deemed critical by the clay industry. This follow-on project achieved following successes: A theoretical model was developed to account for the effects of size-dependent aspect ratios of spheroid particles under different orientations on ultrasound attenuation spectra of concentrated slurries. The theoretical model was confirmed by laboratory tests on kaolin slurries. An algorithm was developed to simulate evolution of particle orientation fields in simple squeezing flows.

  8. Polymer based nanocomposites with nanofibers and exfoliated clay

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.; Reneker, Darrell H.

    2005-01-01

    Polymer solutions, containing clay sheets, were electrospun into nanofibers and microfibers that contained clay sheets inside. Controllable removal of polymer by plasma etching from the surface of fibers revealed the arrangement of clay. The shape, flexibility, size distribution and arrangement of clay sheets were observed by transmission and scanning electron microscopy. The clay sheets were partially aligned in big fibers with normal direction of clay sheets perpendicular to fiber axis. Crumpling of clay sheets inside fibers was observed when the fiber diameter was comparable to the lateral size of clay sheets. Single sheets of clay were observed both by catching clay sheets dispersed in water with electrospun nanofiber mats and by the deliberate removal of most of the polymer in the fibers. Thin, flexible gas barrier films, that are reasonably strong, were assembled from clay sheets and polymer nanofibers. Structure of composite films was characterized with scanning electron microscopy. Continuous film of clay sheets were physically attached to the surface of fiber mats. Spincoating film of polymer and clay sheets was reinforced by electrospun fiber scaffold. Certain alignment of clay sheets was observed in the vicinity of fibers.

  9. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    PubMed Central

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange complex. Adsorption to the clays was essentially immediate and was correlated with the cation-exchange capacity of the clays, indicating that adsorption was primarily to negatively charged sites on the clays. Adsorption was greater with low concentrations of clays in estuarine water than in distilled water, as the higher ionic strength of the estuarine water reduced the electrokinetic potential of both clay and virus particles. The addition of cations (as chloride salts) to distilled water enhanced adsorption, with divalent cations being more effective than monovalent cations and 10(-2) M resulting in more adsorption than 10(-3) M. Potassium ions suppressed reovirus adsorption to montmorillonite, probably by collapsing the clay lattices and preventing the expression of the interlayer-derived cation-exchange capacity. More virus was adsorbed by montmorillonite made homoionic to various mono-, di-, and trivalent cations (except by montmorillonite homoionic to potassium) than by comparable concentrations of kaolinite homoionic to the same cations. The sequence of the amount of adsorption to homoionic montmorillonite was Al greater than Ca greater than Mg greater than Na greater than K; the sequence of adsorption to kaolinite was Na greater than Al greater than Ca greater than Mg greater than K. The constant partition-type adsorption isotherms obtained when the clay concentration was maintained constant and the virus concentration was varied indicated that a fixed proportion of the

  10. Orienting hypnosis.

    PubMed

    Hope, Anna E; Sugarman, Laurence I

    2015-01-01

    This article presents a new frame for understanding hypnosis and its clinical applications. Despite great potential to transform health and care, hypnosis research and clinical integration is impaired in part by centuries of misrepresentation and ignorance about its demonstrated efficacy. The authors contend that advances in the field are primarily encumbered by the lack of distinct boundaries and definitions. Here, hypnosis, trance, and mind are all redefined and grounded in biological, neurological, and psychological phenomena. Solutions are proposed for boundary and language problems associated with hypnosis. The biological role of novelty stimulating an orienting response that, in turn, potentiates systemic plasticity forms the basis for trance. Hypnosis is merely the skill set that perpetuates and influences trance. This formulation meshes with many aspects of Milton Erickson's legacy and Ernest Rossi's recent theory of mind and health. Implications of this hypothesis for clinical skills, professional training, and research are discussed. PMID:25928677

  11. Heteroaggregation of engineered nanoparticles and kaolin clays in aqueous environments.

    PubMed

    Wang, Hongtao; Dong, Ya-nan; Zhu, Miao; Li, Xiang; Keller, Arturo A; Wang, Tao; Li, Fengting

    2015-09-01

    The increasing and wide use of nanoparticles (NPs), including TiO2 and Ag NPs, have raised concerns due to their potential toxicity and environmental impacts. Kaolin is a very common mineral in aquatic systems, and there is a very high probability that nanoparticles (NPs) will interact with these clay minerals. We studied the effect of kaolin particles on the aggregation of NPs under different conditions, including the role of pH, ionic strength (IS), and humic acid (HA). We show that kaolin reduces the energy barrier and the Critical Coagulation Concentration (CCC) at pH 4. At pH 8, even though the energy barrier of the system without kaolin increases, kaolin promotes NP aggregation via heteroaggregation. When IS is equal to or greater than the CCC, on the one hand HA promotes aggregation of TiO2 NPs, but on the other hand HA decreases the rate of Ag NP aggregation because the existence of a surface coating may limit the adsorption of HA on these Ag NPs. In addition, the presence of HA increases the energy barrier and the CCC of the binary system (kaolin + NPs). Thus, the complex interactions of clay, NPs, IS, pH, and HA concentration determine the colloidal stability of the NPs. We find that kaolin is a potential coagulant for removal of NPs that behave like Ag and TiO2. PMID:26001279

  12. Flocculation of Clay and Organic Matter in Turbid Salt Water

    NASA Astrophysics Data System (ADS)

    Reed, A. H.; Yin, H.; Zhang, G.; Tan, X.; Furukawa, Y.

    2010-12-01

    Sediment transport and deposition in estuaries and tidal flats are often dominated by the aggregation of clay and organic matter into composite particles or “flocs”. The stability of the flocs is important in determining the distance over which the sediment is transported and the areas to which the sediment is deposited. During floc transport from riverine to oceanic environments, stability is determined by suspended sediment concentrations, sediment types, organic matter type, fluid flow rates and small scale turbulence. In a series of laboratory experiments, interactions between clay sediments and organic matter were evaluated within a flow column that was filled with saline water. The focus of this investigation was on changes in floc size, density and strength as flow velocities and turbulent stresses were altered. Significant changes in the floc shape, consolidation, density and behavior were determined for flow rates and Reynolds numbers that are common to riverine environments. The variability in floc composition was also shown to influence bulk sediment properties: heat transport, acoustic propagation and shear strength, while sediments were entrained in high-density suspensions and low-density deposits.

  13. Quantitative characterization of non-classic polarization of cations on clay aggregate stability.

    PubMed

    Hu, Feinan; Li, Hang; Liu, Xinmin; Li, Song; Ding, Wuquan; Xu, Chenyang; Li, Yue; Zhu, Longhui

    2015-01-01

    Soil particle interactions are strongly influenced by the concentration, valence and ion species and the pH of the bulk solution, which will also affect aggregate stability and particle transport. In this study, we investigated clay aggregate stability in the presence of different alkali ions (Li+, Na+, K+, and Cs+) at concentrations from10-5 to 10-1 mol L-1. Strong specific ion effects on clay aggregate stability were observed, and showed the order Cs+>K+>Na+>Li+. We found that it was not the effects of ion size, hydration, and dispersion forces in the cation-surface interactions but strong non-classic polarization of adsorbed cations that resulted in these specific effects. In this study, the non-classic dipole moments of each cation species resulting from the non-classic polarization were estimated. By comparing non-classic dipole moments with classic values, the observed dipole moments of adsorbed cations were up to 104 times larger than the classic values for the same cation. The observed non-classic dipole moments sharply increased with decreasing electrolyte concentration. We conclude that strong non-classic polarization could significantly suppress the thickness of the diffuse layer, thereby weakening the electric field near the clay surface and resulting in improved clay aggregate stability. Even though we only demonstrated specific ion effects on aggregate stability with several alkali ions, our results indicate that these effects could be universally important in soil aggregate stability. PMID:25874864

  14. Study of Adsorption and Flocculation Properties of Natural Clays to Remove Prorocentrum lima.

    PubMed

    Louzao, Maria Carmen; Abal, Paula; Fernández, Diego A; Vieytes, Mercedes R; Legido, José Luis; Gómez, Carmen P; Pais, Jesus; Botana, Luis M

    2015-10-01

    High accumulations of phytoplankton species that produce toxins are referred to as harmful algal blooms (HABs). HABs represent one of the most important sources of contamination in marine environments, as well as a serious threat to public health, fisheries, aquaculture-based industries, and tourism. Therefore, methods effectively controlling HABs with minimal impact on marine ecology are required. Marine dinoflagellates of the genera Dinophysis and Prorocentrum are representative producers of okadaic acid (OA) and dinophysistoxins responsible for the diarrhetic shellfish poisoning (DSP) which is a human intoxication caused by the consumption of shellfish that bioaccumulate those toxins. In this work we explore the use of natural clay for removing Prorocentrum lima. We evaluate the adsorption properties of clays in seawater containing the dinoflagellates. The experimental results confirmed the cell removal through the flocculation of algal and mineral particles leading to the formation of aggregates, which rapidly settle and further entrain cells during their descent. Moreover, the microscopy images of the samples enable one to observe the clays in aggregates of two or more cells where the mineral particles were bound to the outer membranes of the dinoflagellates. Therefore, this preliminary data offers promising results to use these clays for the mitigation of HABs. PMID:26426051

  15. Study of Adsorption and Flocculation Properties of Natural Clays to Remove Prorocentrum lima

    PubMed Central

    Louzao, Maria Carmen; Abal, Paula; Fernández, Diego A.; Vieytes, Mercedes R.; Legido, José Luis; Gómez, Carmen P.; Pais, Jesus; Botana, Luis M.

    2015-01-01

    High accumulations of phytoplankton species that produce toxins are referred to as harmful algal blooms (HABs). HABs represent one of the most important sources of contamination in marine environments, as well as a serious threat to public health, fisheries, aquaculture-based industries, and tourism. Therefore, methods effectively controlling HABs with minimal impact on marine ecology are required. Marine dinoflagellates of the genera Dinophysis and Prorocentrum are representative producers of okadaic acid (OA) and dinophysistoxins responsible for the diarrhetic shellfish poisoning (DSP) which is a human intoxication caused by the consumption of shellfish that bioaccumulate those toxins. In this work we explore the use of natural clay for removing Prorocentrum lima. We evaluate the adsorption properties of clays in seawater containing the dinoflagellates. The experimental results confirmed the cell removal through the flocculation of algal and mineral particles leading to the formation of aggregates, which rapidly settle and further entrain cells during their descent. Moreover, the microscopy images of the samples enable one to observe the clays in aggregates of two or more cells where the mineral particles were bound to the outer membranes of the dinoflagellates. Therefore, this preliminary data offers promising results to use these clays for the mitigation of HABs. PMID:26426051

  16. Quantitative Characterization of Non-Classic Polarization of Cations on Clay Aggregate Stability

    PubMed Central

    Hu, Feinan; Li, Hang; Liu, Xinmin; Li, Song; Ding, Wuquan; Xu, Chenyang; Li, Yue; Zhu, Longhui

    2015-01-01

    Soil particle interactions are strongly influenced by the concentration, valence and ion species and the pH of the bulk solution, which will also affect aggregate stability and particle transport. In this study, we investigated clay aggregate stability in the presence of different alkali ions (Li+, Na+, K+, and Cs+) at concentrations from10−5 to 10−1 mol L−1. Strong specific ion effects on clay aggregate stability were observed, and showed the order Cs+>K+>Na+>Li+. We found that it was not the effects of ion size, hydration, and dispersion forces in the cation–surface interactions but strong non-classic polarization of adsorbed cations that resulted in these specific effects. In this study, the non-classic dipole moments of each cation species resulting from the non-classic polarization were estimated. By comparing non-classic dipole moments with classic values, the observed dipole moments of adsorbed cations were up to 104 times larger than the classic values for the same cation. The observed non-classic dipole moments sharply increased with decreasing electrolyte concentration. We conclude that strong non-classic polarization could significantly suppress the thickness of the diffuse layer, thereby weakening the electric field near the clay surface and resulting in improved clay aggregate stability. Even though we only demonstrated specific ion effects on aggregate stability with several alkali ions, our results indicate that these effects could be universally important in soil aggregate stability. PMID:25874864

  17. Radiocarbon Ages of Postglacial Lake Clays near Michigan City, Indiana.

    PubMed

    Winkler, E M

    1962-08-17

    Two radiocarbon dates were obtained for postglacial clays. One sample, 6350 years old, was taken from a bed of compacted and carbonized wood just above a bed of pebbly clay. Overlying the woody bed is 5(1/2) feet of organic bluish clays and beach sands near the present lake level. The upper clay layer contained a younger wood sample, 5475 years old. The blue clays are of shallow swamp origin and were deposited during the late low-water stage of Lake Chippewa; the pebbly clay is assumed to be of Glenwood age (about 11,000 years) or older. PMID:17749630

  18. EDITORIAL: Optical orientation Optical orientation

    NASA Astrophysics Data System (ADS)

    SAME ADDRESS *, Yuri; Landwehr, Gottfried

    2008-11-01

    priority of the discovery in the literature, which was partly caused by the existence of the Iron Curtain. I had already enjoyed contact with Boris in the 1980s when the two volumes of Landau Level Spectroscopy were being prepared [2]. He was one of the pioneers of magneto-optics in semiconductors. In the 1950s the band structure of germanium and silicon was investigated by magneto-optical methods, mainly in the United States. No excitonic effects were observed and the band structure parameters were determined without taking account of excitons. However, working with cuprous oxide, which is a direct semiconductor with a relative large energy gap, Zakharchenya and his co-worker Seysan showed that in order to obtain correct band structure parameters, it is necessary to take excitons into account [3]. About 1970 Boris started work on optical orientation. Early work by Hanle in Germany in the 1920s on the depolarization of luminescence in mercury vapour by a transverse magnetic field was not appreciated for a long time. Only in the late 1940s did Kastler and co-workers in Paris begin a systematic study of optical pumping, which led to the award of a Nobel prize. The ideas of optical pumping were first applied by Georges Lampel to solid state physics in 1968. He demonstrated optical orientation of free carriers in silicon. The detection method was nuclear magnetic resonance; optically oriented free electrons dynamically polarized the 29Si nuclei of the host lattice. The first optical detection of spin orientation was demonstrated by with the III-V semiconductor GaSb by Parsons. Due to the various interaction mechanisms of spins with their environment, the effects occurring in semiconductors are naturally more complex than those in atoms. Optical detection is now the preferred method to detect spin alignment in semiconductors. The orientation of spins in crystals pumped with circularly polarized light is deduced from the degree of circular polarization of the recombination

  19. Chlorination of alumina in kaolinitic clay

    NASA Astrophysics Data System (ADS)

    Grob, B.; Richarz, W.

    1984-09-01

    The chlorination of alumina in kaolinitic clay with Cl2 and CO gas mixtures was studied gravimetrically. The effects of the calcination method and of NaCl addition on the reactivity of the clay were examined. Fast reaction rates were achieved only with samples previously exposed to a sulfating treatment. Optimum conditions, with maximum yield and selectivity to A1C13 and minimum SiO2 conversion, were found between 770 and 970 K. At higher temperatures the SiCl4 formed poisons the reactive alumina surface by selective chemisorption with a marked decrease of the reaction rate.

  20. Numerical Modelling of Embankment on Soft Clay

    NASA Astrophysics Data System (ADS)

    Nujid, M. M.; Taha, M. R.

    2016-07-01

    This paper aims to predict deformation of embankment on soft clay of Muar. The prediction performance focusing on displacement at critical fill height of 5.5 m. The study was based on reported result in 1992. With the aid of computer intelligence, the advanced constitutive soil models could be adopted to analyze the soft clay behavior. The COMSOL Multiphysics (v4.4) has been used to simulate the problem with coupled physics available in the software. The vertical displacements are in good agreement close to published result.

  1. Reducing the Cation Exchange Capacity of Lithium Clay to Form Better Dispersed Polymer-Clay Nanocomposites

    NASA Technical Reports Server (NTRS)

    Liang, Maggie

    2004-01-01

    Polymer-clay nanocomposites have exhibited superior strength and thermo- oxidative properties as compared to pure polymers for use in air and space craft; however, there has often been difficulty completely dispersing the clay within the matrices of the polymer. In order to improve this process, the cation exchange capacity of lithium clay is first lowered using twenty-four hour heat treatments of no heat, 130 C, 150 C, or 170 C to fixate the lithium ions within the clay layers so that they are unexchangeable. Generally, higher temperatures have generated lower cation exchange capacities. An ion exchange involving dodecylamine, octadecylamine, or dimethyl benzidine (DMBZ) is then employed to actually expand the clay galleries. X-ray diffraction and transmission electron microscopy can be used to determine whether the clay has been successfully exfoliated. Finally, resins of DMBZ with clay are then pressed into disks for characterization using dynamic mechanical analyzer and oven- aging techniques in order to evaluate their glass transition, modulus strength, and thermal-oxidative stability in comparison to neat DMBZ. In the future, they may also be tested as composites for flexural and laminar shear strength.

  2. Synthesis and characterization of a PbO{sub 2}-clay nanocomposite: Removal of lead from water using montmorillonite

    SciTech Connect

    Aroui, L.; Zerroual, L.; Boutahala, M.

    2012-02-15

    Graphical abstract: The replacement of Na by Pb in the interlayer space of the smectite leads to a decrease in the intensity of the the (0 0 1) reflection as the concentration of lead nitrate increases. A significant restructuring at the particle scale is observed leading probably to the exfoliation of the caly. In addition, the thermal behaviour of the montmorillonite samples with regard to their dehydration and dehydroxilation capacities is significantly influenced. This leads to a lowering of the water content and a decrease in the ionic conductivity of the clay. Highlights: Black-Right-Pointing-Pointer In the clay, Pb replaces Na ions and a significant restructuring at the particle scale is observed. Black-Right-Pointing-Pointer Pb influenced significantly the thermal behaviour of the clay with regard to its dehydration. Black-Right-Pointing-Pointer In the interlayer space, the exchange of Na by Pb leads to a decrease in the protonic conductivity. Black-Right-Pointing-Pointer A PbO{sub 2}-clay nanocomposite material with good conductivity is synthesized. -- Abstract: The aim of this paper is to present the results obtained with Pb(II) sorption on an Algerian Clay. The experiments were carried out using a batch process. Powder X-rays diffraction patterns (PXRD) prove that in the montmorillonite Pb replaces Na ions. A significant restructuring at the particle scale is observed leading to the disappearance of the d{sub 001} reflection of the clay at high concentrations of lead. The replacement of hydrated Na with Pb ions influenced significantly the thermal behaviour of the montmorillonite samples with regard to their dehydration and dehydroxilation capacities with a lowering of the water content. A PbO{sub 2}-clay composite material with good electrical conductivity is synthesized.

  3. How clays affect fault strength and slip behavior: Lessons from SAFOD

    NASA Astrophysics Data System (ADS)

    van der Pluijm, B. A.; Schleicher, A. M.; Warr, L.

    2010-12-01

    The strength and slip behavior of upper crustal faults has been attributed to (i) values of normal stress, (ii) pore-fluid pressure, and (iii) frictional properties. Direct observations on natural fault rocks provide compelling evidence for the role of localized neomineralization, as demonstrated by our work on samples from the San Andreas Fault Observatory at Depth (SAFOD) drillhole at Parkfield, California. Mudrock samples from fault zones at ~3066 m and ~3296 m measured depth (MD) show variably spaced and interconnected networks of displacement surfaces that consist of host rock particles that are abundantly coated by polished films with occasional striations. Transmission electron microscopy and X-ray diffraction study of the surfaces reveal the occurrence of neocrystallized thin-film clay coatings containing illite-smectite (I-S) and chlorite-smectite (C-S) phases. X-ray texture goniometry shows that the clay crystallographic fabric of these faults rocks is characteristically low, in spite of an abundance of clay phases. 40Ar/39Ar dating of the illitic coatings demonstrate recent crystallization and reveals the initiation of an “older” fault strand (~8 Ma) at 3066 m MD, and a “younger” fault strand (~4 Ma) at 3296 m MD. Today, the younger strand is the site of active creep behavior, reflecting continued activation of clay-weakened zones. We propose that fault creep is controlled by the localization of thin (< 100nm thick) nanocoatings on fracture surfaces that are sufficiently smectite-rich and interconnected to allow slip with minimal breakage of stronger matrix clasts. Displacements are accommodated by frictional slip along coated particle surfaces, in combination with intracrystalline deformation of the mineral lattice, resulting from crystal dissolution, mass transfer and growth of expandable clays. The highly localized concentration of both I-S and C-S minerals does not require volumetrically large mass transfer. A scenario is proposed where

  4. Xenon-129 NMR study of the microporous structure of clays and pillared clays

    SciTech Connect

    Tsiao, C.; Carrado, K.A.

    1990-01-01

    {sup 129}Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diameter of montmorillonite increases, for example, from 5.4 {Angstrom} to 8.0 {Angstrom} after pillaring cheto-montmorillonite with aluminum polyoxohydroxy Keggin cations. The data are consistent with X-ray powder diffraction results, which show a corresponding increase in the interlamellar gallery height from 5.6 {Angstrom} to 8.4 {Angstrom}.

  5. EDITORIAL: Optical orientation Optical orientation

    NASA Astrophysics Data System (ADS)

    SAME ADDRESS *, Yuri; Landwehr, Gottfried

    2008-11-01

    priority of the discovery in the literature, which was partly caused by the existence of the Iron Curtain. I had already enjoyed contact with Boris in the 1980s when the two volumes of Landau Level Spectroscopy were being prepared [2]. He was one of the pioneers of magneto-optics in semiconductors. In the 1950s the band structure of germanium and silicon was investigated by magneto-optical methods, mainly in the United States. No excitonic effects were observed and the band structure parameters were determined without taking account of excitons. However, working with cuprous oxide, which is a direct semiconductor with a relative large energy gap, Zakharchenya and his co-worker Seysan showed that in order to obtain correct band structure parameters, it is necessary to take excitons into account [3]. About 1970 Boris started work on optical orientation. Early work by Hanle in Germany in the 1920s on the depolarization of luminescence in mercury vapour by a transverse magnetic field was not appreciated for a long time. Only in the late 1940s did Kastler and co-workers in Paris begin a systematic study of optical pumping, which led to the award of a Nobel prize. The ideas of optical pumping were first applied by Georges Lampel to solid state physics in 1968. He demonstrated optical orientation of free carriers in silicon. The detection method was nuclear magnetic resonance; optically oriented free electrons dynamically polarized the 29Si nuclei of the host lattice. The first optical detection of spin orientation was demonstrated by with the III-V semiconductor GaSb by Parsons. Due to the various interaction mechanisms of spins with their environment, the effects occurring in semiconductors are naturally more complex than those in atoms. Optical detection is now the preferred method to detect spin alignment in semiconductors. The orientation of spins in crystals pumped with circularly polarized light is deduced from the degree of circular polarization of the recombination

  6. Oriental noodles.

    PubMed

    Hou, G

    2001-01-01

    Oriental noodles have been consumed for thousands of years and remain an important part in the diet of many Asians. There is a wide variety of noodles in Asia with many local variations as result of differences in culture, climate, region and a host of other factors. In this article noodle classification, formulation, processing and evaluation are reviewed, with emphasis on eight major types. Wheat quality requirements, basic flour specifications, ingredient functions, and production variables are identified for different noodles. In the evaluation of flour for noodle making, three key quality attributes are considered: processability, noodle color and texture. Noodle process behavior is particularly important in the modern industrial production. Each noodle type has its own unique color and texture characteristics. Flour color, protein content, ash content, yellow pigment and polyphenol oxidase activity are important factors responsible for noodle color. Starch characteristics, protein content and quality play major roles in governing the texture of cooked noodles. However, the relative importance of starch and proteins varies considerably with noodle type. Starch pasting quality is the primary trait determining the eating quality of Japanese and Korean noodles that are characterized by soft and elastic texture, while protein quantity and strength are very important to Chinese-type noodles that require firm bite and chewy texture. Other factors such as ingredients added in the noodle formula and processing variables used during noodle preparation also affect the cooked noodle texture as well. PMID:11285682

  7. Sub-THz complex dielectric constants of smectite clay thin samples with Na+/Ca++ ions

    NASA Astrophysics Data System (ADS)

    Rahman, Rezwanur; McCarty, Douglas K.; Prasad, Manika

    2015-09-01

    We implement a technique to characterize the electromagnetic properties at frequencies 100 to 165 GHz (3 cm-1 to 4.95 cm-1) of oriented smectite samples using an open cavity resonator connected to a submillimeter wave VNA (Vector Network Analyzer). We measured dielectric constants perpendicular to the bedding plane on oriented Na+ ion and Ca++ ion stabilized smectite samples deposited on a glass slide at ambient laboratory conditions (room temperature and room light). The clay layer is much thinner (˜30 μm) than the glass substrate (˜2.18 mm). The real part of dielectric constant, ɛre, is essentially constant over this frequency range but is larger in Na+ ion than in Ca++ ion infused clay. The total electrical conductivity (associated with the imaginary part of dielectric constant, ɛim) of both samples increases monotonically at lower frequencies (<110 GHz) but shows rapid increase for Na+ ions in the regime > 110 GHz. The dispersion of the samples display a dependence on the ionic strength in the clay interlayers, i.e., ζ potential in the Stern layers.

  8. Classroom Instruction: The Influences of Marie Clay

    ERIC Educational Resources Information Center

    McNaughton, Stuart

    2014-01-01

    Marie Clay's body of work has influenced classroom instruction in direct and indirect ways, through large overarching themes in our pedagogical content knowledge as well as specific smart practices. This paper focuses on her the contributions to our thinking about instruction which come from two broad theoretical concepts; emergent literacy…

  9. REPORT OF WORKSHOP ON GEOSYNTHETIC CLAY LINERS

    EPA Science Inventory

    The purpose of the report is to summarize the information presented at the Geosynthetic Clay Liner (GCL) workshop held on July 9-10, 1992. The report does not represent the full extent of the information available on geosynthetic liners. Readers are directed to the summary of th...

  10. Diffusion in Clay Layers and Groundwater Remediation

    EPA Science Inventory

    In a collaborative SERDP-funded study, researchers from the Air Force Institute of Technology, the U.S. Environmental Protection Agency, and the University of Michigan developed a numerical model that simulates the enhanced transport of CAHs into and out of low permeability clay ...

  11. Palaeoceanographic approach to the Kimmeridge Clay Formation

    SciTech Connect

    Miller, R.G. )

    1988-08-01

    The Upper Jurassic/Lower Cretaceous Kimmeridge Clay Formation (KCF) is northern Europe's premier source rock and can be understood using a new but relatively simple oceanographic model. This explains or accommodates most current observations about the KCF and its depositional environment and draws upon paleogeographic, paleoclimatic, geochemical, sedimentological, and paleontological evidence.

  12. HYDRAULIC CONDUCTIVITY OF THREE GEOSYNTHETIC CLAY LINERS

    EPA Science Inventory

    The hydraulic conductivity of three 2.9 m2 (32 sq ft) geosynthetic clay liners (GCLs) was measured. Tests were performed on individual sheets of the GCLs, on overlapped pieces of GCLs, and on composite liners consisting of a punctured geomembrane overlying a GCL. Hyd...

  13. Calm, Cool, and Comfortable in Clay

    ERIC Educational Resources Information Center

    Stylianou, Xanthippi Cynthia

    2010-01-01

    The author's fourth-grade students had just finished a drawing unit that focused on the human figure. Projects included charcoal gesture drawings and chalk manikin drawings in chiaroscuro. She wanted to integrate a new medium for students to continue their study of the human figure. Since students are always excited to work with clay, making clay…

  14. Bauxite washing for the removal of clay

    NASA Astrophysics Data System (ADS)

    Ahmad, Ishaq; Hartge, Ernst-Ulrich; Werther, Joachim; Wischnewski, Reiner

    2014-11-01

    Clay impurities associated with bauxite negatively affect the Bayer process for alumina production. These impurities should be removed as far as possible by a beneficiation technique before the ore is used as feed for the Bayer process. In this current investigation, bauxite washing was conducted in the laboratory. Bauxite washing is a physical process that causes the disintegration and deagglomeration of the clay matrix, and bauxite is liberated from the clay (mainly rich in silica). Subsequently, separation occurs with the assistance of wet screening at a predetermined cut size. Three techniques were investigated in the laboratory: drum washing, water-jet washing, and ultrasonic washing. Various operating parameters were investigated for drum washing and water-jet washing, including materials retention time, drum rotation speed, solid concentration, water-jet spray duration, pressure, and height. We concluded that the retention time of bauxite inside the drum at a solid concentration of 55wt% and a drum rotation speed of 31 r/min is the dominant parameter for the removal of clay from the bauxite surface.

  15. Transport of Organic Solutes in Clay Formations

    EPA Science Inventory

    The research is a pilot investigation for the SERDP (Strategic Environmental Research and Development Program, DoD) founded project, Impact of Clay-DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones, from 2010-2012. The report tries to s...

  16. Clay Corner: Recreating Chinese Bronze Vessels.

    ERIC Educational Resources Information Center

    Gamble, Harriet

    1998-01-01

    Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

  17. INTERIOR VIEW ON SEVENTH FLOOR AT CORNER OF CLAY AND ...

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

    INTERIOR VIEW ON SEVENTH FLOOR AT CORNER OF CLAY AND 15TH STREETS. LARGE SECTIONS OF DEMOLISHED SHEET METAL CORNICE FROM BUILDING EXTERIOR VISIBLE FOREGROUND - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  18. INTERIOR VIEW ON MEZZANINE ALONG EAST (CLAY STREET) FRONT FACING ...

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

    INTERIOR VIEW ON MEZZANINE ALONG EAST (CLAY STREET) FRONT FACING OAKLAND CITY HALL. TYPICAL INTERIOR CONDITIONS OF PARTIAL DEMOLITION; WINDOWS, WINDOW FRAMES, SUSPENDED CEILING, AND MOVABLE PARTITION WALLS REMOVED - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  19. The impact of long-term irrigation on the degree of aggregation and the mineralogical composition of the clay fraction in dark chestnut soils of the Transvolga region

    NASA Astrophysics Data System (ADS)

    Chizhikova, N. P.; Baranovskaya, V. A.; Khitrov, N. B.

    2011-08-01

    Dark chestnut soils of the Ershov Experimental Station in the Transvolga region are characterized by the even distribution and aggregation of clay minerals in the profile. Hydromica, chlorite, kaolinite, and smectitic minerals predominate in the clay (<1 μm) fraction. The smectitic phase consists of randomly ordered mixed-layered minerals of the following types: mica-smectite with a low (<50%) content of smectite layers, mica-smectite with a high (>50%) content of smectite layers, and chlorite-smectite. In some horizons, the smectitic phase occurs in the superdispersed state. The long-term irrigation of these soils with fresh water of the Volga River has led to certain changes in the composition and properties of the clay particles. The weakening of bonds between them has taken place. As a result, the content of water-peptizable clay has increased by two times, and the content of aggregated clay of the first category (AC1) has increased by 1.5 times at the expense of a decrease in the contents of tightly bound clay (TBC) and aggregated clay of the second category (AC2). Also, the redistribution of organic matter bound with clay particles has taken place: its content in the AC1 fraction has decreased, whereas its content in the AC2 and TBC fractions has increased. In the topsoil horizon, the amount of the smectitic phase has lowered, whereas the contents of hydromica, kaolinite, and fine-dispersed quartz in the clay fraction have increased. In general, some amorphization of the clay material has occurred. The periodic alkalization of the soil solutions upon irrigation has led to the conversion of the smectitic phase into the superdispersed state in the entire soil profile.

  20. Mineralogical variables that control the antibacterial effectiveness of a natural clay deposit.

    PubMed

    Morrison, Keith D; Underwood, Jennifer C; Metge, David W; Eberl, Dennis D; Williams, Lynda B

    2014-08-01

    As antibiotic-resistant bacterial strains emerge and pose increased global health risks, new antibacterial agents are needed as alternatives to conventional antimicrobials. Naturally occurring antibacterial clays have been identified which are effective in killing antibiotic-resistant bacteria. This study examines a hydrothermally formed antibacterial clay deposit near Crater Lake, OR (USA). Our hypothesis is that antibacterial clays buffer pH and Eh conditions to dissolve unstable mineral phases containing transition metals (primarily Fe(2+)), while smectite interlayers serve as reservoirs for time release of bactericidal components. Model pathogens (Escherichia coli ATCC 25922 and Staphylococcus epidermidis ATCC 14990) were incubated with clays from different alteration zones of the hydrothermal deposit. In vitro antibacterial susceptibility testing showed that reduced mineral zones were bactericidal, while more oxidized zones had variable antibacterial effect. TEM images showed no indication of cell lysis. Cytoplasmic condensation and cell wall accumulations of <100 nm particles were seen within both bacterial populations. Electron energy loss analysis indicates precipitation of intracellular Fe(3+)-oxide nanoparticles (<10 nm) in E. coli after 24 h. Clay minerals and pyrite buffer aqueous solutions to pH 2.5-3.1, Eh > 630 mV and contain elevated level (mM) of soluble Fe (Fe(2+) and Fe(3+)) and Al(3+). Our interpretation is that rapid uptake of Fe(2+) impairs bacterial metabolism by flooding the cell with excess Fe(2+) and overwhelming iron storage proteins. As the intracellular Fe(2+) oxidizes, it produces reactive oxygen species that damage biomolecules and precipitates Fe-oxides. The ability of antibacterial clays to buffer pH and Eh in chronic non-healing wounds to conditions of healthy skin appears key to their healing potential and viability as an alternative to conventional antibiotics. PMID:24258612

  1. Dynamics of confined reactive water in Smectic clay-zeolite composites.

    SciTech Connect

    Pitman, Michael C.; Van Duin, Adri C. T.

    2012-01-01

    The dynamics of water confined to mesoporous regions in minerals such as swelling clays and zeolites is fundamental to a wide range of resource management issues impacting many processes on a global scale, including radioactive waste containment, desalination, and enhanced oil recovery. Large-scale atomic models of freely diffusing multilayer smectite particles at low hydration confined in a silicalite cage are used to investigate water dynamics in the composite environment with the ReaxFF reactive force field over a temperature range of 300 647 K. The reactive capability of the force field enabled a range of relevant surface chemistry to emerge, including acid/base equilibria in the interlayer calcium hydrates and silanol formation on the edges of the clay and inner surface of the zeolite housing. After annealing, the resulting clay models exhibit both mono- and bilayer hydration structures. Clay surface hydration redistributed markedly and yielded to silicalite water loading. We find that the absolute rates and temperature dependence of water dynamics compare well to neutron scattering data and pulse field gradient measures from relevant samples of Ca-montmorillonite and silicalite, respectively. Within an atomistic, reactive context, our results distinguish water dynamics in the interlayer Ca(OH)2 nH2O environment from water flowing over the clay surface, and from water diffusing within silicalite. We find that the diffusion of water when complexed to Ca hydrates is considerably slower than freely diffusing water over the clay surface, and the reduced mobility is well described by a difference in the Arrhenius pre-exponential factor rather than a change in activation energy.

  2. Dynamics of confined reactive water in smectite clay-zeolite composites

    SciTech Connect

    Pitman, Michael C.; Van Duin, Adri C. T.

    2012-01-01

    The dynamics of water confined to mesoporous regions in minerals such as swelling clays and zeolites is fundamental to a wide range of resource management issues impacting many processes on a global scale, including radioactive waste containment, desalination, and enhanced oil recovery. Large-scale atomic models of freely diffusing multilayer smectite particles at low hydration confined in a silicalite cage are used to investigate water dynamics in the composite environment with the ReaxFF reactive force field over a temperature range of 300 647 K. The reactive capability of the force field enabled a range of relevant surface chemistry to emerge, including acid/base equilibria in the interlayer calcium hydrates and silanol formation on the edges of the clay and inner surface of the zeolite housing. After annealing, the resulting clay models exhibit both mono- and bilayer hydration structures. Clay surface hydration redistributed markedly and yielded to silicalite water loading. We find that the absolute rates and temperature dependence of water dynamics compare well to neutron scattering data and pulse field gradient measures from relevant samples of Ca-montmorillonite and silicalite, respectively. Within an atomistic, reactive context, our results distinguish water dynamics in the interlayer Ca(OH)2 nH2O environment from water flowing over the clay surface, and from water diffusing within silicalite. We find that the diffusion of water when complexed to Ca hydrates is considerably slower than freely diffusing water over the clay surface, and the reduced mobility is well described by a difference in the Arrhenius pre-exponential factor rather than a change in activation energy.

  3. Orientational ordering of Janus colloids in cholesteric liquid crystals.

    PubMed

    Rudyak, Vladimir Yu; Emelyanenko, Alexander V

    2015-10-01

    In this paper we show that Janus colloids, which are spherical particles with hybrid anchoring conditions, have preferable orientations in cholesteric media depending on the cholesteric wave vector. Simulations reveal that the tilt angle of a particle varies greatly with variation of the particle diameter to the cholesteric pitch ratio, which makes it possible to stabilize the appropriate particle orientation and to control it by variation of the cholesteric pitch. PMID:26291514

  4. Zeta potential measurements on three clays from Turkey and effects of clays on coal flotation

    SciTech Connect

    Hussain, S.A.; Demirici, S.; Oezbayoglu, G.

    1996-12-25

    There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation.

  5. Zeta Potential Measurements on Three Clays from Turkey and Effects of Clays on Coal Flotation

    PubMed

    Hussain; Dem&idot;rc&idot;; özbayoğlu

    1996-12-25

    There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation. PMID:8978557

  6. Clays and clay minerals in Bikaner: Sources, environment pollution and management

    NASA Astrophysics Data System (ADS)

    Gayatri, Sharma; Anu, Sharma

    2016-05-01

    Environmental pollution can also be caused by minerals which include natural as well as human activities. Rapid urbanization, consumerist life style, anthropogenic deeds are increasing environmental pollution day by day. Fluctuation in our ecosystem or polluted environment leads to many diseases and shows adverse effects on living organisms. The main aim of this paper is to highlight the environmental pollution from clays and clay minerals and their mitigation..

  7. Soft X-ray spectromicroscopy study of mineral-organic matter associations in pasture soil clay fractions.

    PubMed

    Chen, Chunmei; Dynes, James J; Wang, Jian; Karunakaran, Chithra; Sparks, Donald L

    2014-06-17

    There is a growing acceptance that associations with soil minerals may be the most important overarching stabilization mechanism for soil organic matter. However, direct investigation of organo-mineral associations has been hampered by a lack of methods that can simultaneously characterize organic matter (OM) and soil minerals. In this study, STXM-NEXAFS spectroscopy at the C 1s, Ca 2p, Fe 2p, Al 1s, and Si 1s edges was used to investigate C associations with Ca, Fe, Al, and Si species in soil clay fractions from an upland pasture hillslope. Bulk techniques including C and N NEXAFS, Fe K-edge EXAFS spectroscopy, and XRD were applied to provide additional information. Results demonstrated that C was associated with Ca, Fe, Al, and Si with no separate phase in soil clay particles. In soil clay particles, the pervasive C forms were aromatic C, carboxyl C, and polysaccharides with the relative abundance of carboxyl C and polysaccharides varying spatially at the submicrometer scale. Only limited regions in the soil clay particles had aliphatic C. Good C-Ca spatial correlations were found for soil clay particles with no CaCO3, suggesting a strong role of Ca in organo-mineral assemblage formation. Fe EXAFS showed that about 50% of the total Fe in soils was contained in Fe oxides, whereas Fe-bearing aluminosilicates (vermiculite and Illite) accounted for another 50%. Fe oxides in the soil were mainly crystalline goethite and hematite, with lesser amounts of poorly crystalline ferrihydrite. XRD revealed that soil clay aluminosilicates were hydroxy-interlayered vermiculite, Illite, and kaolinite. C showed similar correlation with Fe to Al and Si, implying a similar association of Fe oxides and aluminosilicates with organic matter in organo-mineral associations. These direct microscopic determinations can help improve understanding of organo-mineral interactions in soils. PMID:24837340

  8. FACING NORTH ALONG CLAY STREET, SHOWING BUILDINGS ON THE WEST ...

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

    FACING NORTH ALONG CLAY STREET, SHOWING BUILDINGS ON THE WEST SIDE OF CLAY STREET, FROM LEFT TO RIGHT: JOHN BREUNER AND COMPANY BUILDING (FOREGROUND), HOTEL TOURAINE (MIDDLE), AND THE PACIFIC GAS AND ELECTRIC CO. BUILDING - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  9. Clay Menagerie: An Interview with Patricia Uchill Simons.

    ERIC Educational Resources Information Center

    Gamble, Harriet

    2001-01-01

    Presents an interview with artist Patricia Uchill Simons, focusing on her history as a clay artist, why she uses clay, when she started making her menagerie of animals, her process for creating her artwork, her teaching experience, and why she believes clay is a good medium for students. (CMK)

  10. Enrichment and activation of smectite-poor clay

    NASA Astrophysics Data System (ADS)

    Sarceviča, Inese; Kostjukovs, Juris; Actiņš, Andris

    2011-06-01

    A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

  11. Anisotropy in Experimentally Compressed Kaolinite-Illite-Quartz Aggregates: Microstructure, Preferred Orientation and Acoustic Velocities

    NASA Astrophysics Data System (ADS)

    Voltolini, M.; Wenk, H.; Mondol, N. H.; Bjørlykke, K.; Jahren, J.

    2007-12-01

    Shales and mudstones composed of clay minerals and quartz are important sedimentary rocks that frequently display anisotropy of physical properties. This study investigates anisotropy in experimentally compressed kaolinite-illite-quartz aggregates by determining preferred orientation (texture) of component phases and comparing results with acoustic anisotropy. Sample were prepared compressing clay (81% kaolinite, 14% illite and 4% K-feldspar)-silt (~99% quartz) mixtures (0 to 100% clay) at 5 and 50 MPa vertical effective stress to explore the role of clay content and compaction stress on the elastic properties. Optical and scanning electron microscopy have been used to characterize microstructures. Texture patterns are quantified based on synchrotron X-ray diffraction patterns analyzed with the Rietveld method. Preferred orientation of quartz is more or less random. Clay minerals are strongly oriented. Pole figures display axisymmetric (001) maxima parallel to the compression direction, ranging in strength from 1.6 to 8 multiples of a random distribution. Texture strength strongly increases with compaction pressure and clay content. Both microstructure and preferred orientation are essential contributions to aggregate elastic properties that have been calculated by averaging single crystal properties over the orientation distributions. Calculated P-wave velocity anisotropies range from 0% (100% quartz) to 44% (100% clay, 50 MPa). Anisotropy roughly doubles by increasing the vertical effective stress from 5 to 50 MPa. In experiments only P- and S-wave velocities parallel to the compression direction were measured and values (2-3 km/s) are much lower than those predicted by single crystal averaging (5-7 km/s) which we attribute mainly to the influence of porosity that was not considered in the model. With these experimental compaction data we are currently refining a model to determine macroscopic properties of mudstones and shales based on detailed information of

  12. Molecular Modeling of the Binding Structures in the Interlayer Adsorption of a Tetracycline Antibiotic by Smectite Clays

    NASA Astrophysics Data System (ADS)

    Aristilde, L.

    2009-12-01

    A controlling factor in the fate of antibiotics in the environment is their sequestration in soil particles including clay minerals. Of special interest is the interlayer adsorption by smectite clays, which has been shown to influence both the bioavailability and persistence of antibiotics in the soil environment. However, the interlayer structures of the bound antibiotics, essential to an accurate understanding of the adsorption mechanisms, are not well understood. Molecular simulations of oxytetracycline (OTC) with a model montmorillonite (MONT) clay were performed to gain insights into these structures for tetracycline antibiotics. Monte Carlo simulations were used for explorations of the clay layer spacing required for the adsorption of the antibiotic under different hydration states of the clay interlayer; these preliminary results were validated with previous X-ray diffraction patterns obtained following sorption experiments of OTC with MONT. Molecular dynamics relaxation simulations were performed subsequently in order to obtain geometry-optimized structures of the binding conformations of the intercalated antibiotic in the model MONT layers. This study contributes to a mechanistic understanding of the factors controlling the interlayer adsorption of the tetracycline antibiotics by the expandable smectite clay minerals. Figure 1. Optimized Monte Carlo simulation cell of OTC in the interlayer of MONT: perspective side view (top) and bottom view (bottom).

  13. Microwave-assisted synthesis, characterization and antibacterial activity of Ag/ZnO nanoparticles supported bentonite clay.

    PubMed

    Motshekga, Sarah C; Ray, Suprakas S; Onyango, Maurice S; Momba, Maggie N B

    2013-11-15

    Composites of silver-zinc oxide nanoparticles supported on bentonite clay were synthesized by the microwave-assisted synthesis method for use as an antibacterial material. Silver nitrate was used as the precursor of silver nanoparticles while zinc oxide nanoparticles were commercially sourced. The composites were characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared (FTIR) and BET surface area measurements. XRD spectra showed peaks of silver confirming the formation of the silver and not of the silver nitrate or any other impurity of the metal. Meanwhile TEM confirmed the formation of silver and zinc oxide nanoparticles on the clay layers, with particle sizes ranging from 9-30 nm and 15-70 nm, respectively. The antibacterial activities of the composites were evaluated against Gram negative Escherichia coli bacteria and Gram positive Enterococcus faecalis bacteria by the disc diffusion method. Whereas both composites of Ag-clay and ZnO-clay showed good antibacterial activity against bacteria, a better antibacterial activity was observed with Ag/ZnO-clay composite. The results therefore reveal that Ag/ZnO-clay composite is a promising bactericide that can be used for deactivating microbes in water. PMID:24076479

  14. [Effect of treatments of hydrogen peroxide and sodium dithionite-citrate-bicarbonate on clay minerals of red earth sediments].

    PubMed

    Li, Rong-Biao; Hong, Han-Lie; Yin, Ke; Wang, Chao-Wen; Gao, Wen-Peng; Han, Wen; Wu, Qing-Feng

    2013-04-01

    As classical procedures for pretreatment of soil sediments, hydrogen peroxide (H2O2) and sodium dithionite-citrate-bicarbonate (DCB) treatment methods are very important in removing the organic matter and iron oxides acting as cementing agents in the soils. However, both of these methods have less been focused on the effect on the clay minerals when separating. Here, we report the comparable methods between H2O2 and DCB to reveal their effect on clay minerals in red earth sediments using X-ray diffraction (XRD). The XRD results suggested that mineral particles can be totally decentralized by either H2O2 or DCB method in the soils and high purity clay minerals can be obtained by separating quartz and other impurities from clay minerals effectively. However, the XRD data were distorted by the DCB treatment owning to the cation exchange between Na+ and interlayer cation. On the contrary, the authentic data can be obtained by H2O2 treatment. Therefore, the H2O2 treatment seems to be a more appropriate method to obtain authentic information of clay mineralogy when separating of clay minerals from red earth sediments. PMID:23841441

  15. Synthesis of ZnO nanoparticles on a clay mineral surface in dimethyl sulfoxide medium.

    PubMed

    Németh, József; Rodríguez-Gattorno, Geonel; Díaz, David; Vázquez-Olmos, América R; Dékány, Imre

    2004-03-30

    Nanocrystalline ZnO particles have been prepared with different methods using zinc cyclohexanebutyrate as precursor in dimethyl sulfoxide (DMSO) medium via alkaline hydrolysis. A series of preparations were carried out in the presence of layered silicates (kaolinite and montmorillonite). It was revealed by different measurement techniques that the presence of the clay minerals has a stabilization influence on the size of the ZnO nanocrystals. UV-vis absorption spectra show a blue shift when the nanoparticles are prepared in the presence of the clay minerals. The average particle diameters calculated from the Brus equation ranged from 2.6 to 13.0 nm. The UV-vis spectra of the synthesized nanoparticles did not show any red shift after 2-3 days, demonstrating that stable ZnO nanocrystals are present in the dispersions. The presence of the ZnO nanoparticles was also proven by fluorescence measurements. A number of the nanoparticles are incorporated into the interlamellar space of the clays, and an intercalated structure is formed as proven by X-ray diffraction (XRD) measurements. The size of the nanoparticles in the interlamellar space is in the range of 1-2 nm according to the XRD patterns. Transmission electron microscopy and high-resolution transmission electron microscopy investigations were applied to determine directly the particle size and the size distribution of the nanoparticles. PMID:15835163

  16. The origin and early genesis of clay bands in youthful sandy soils along lake Michigan, U.S.A.

    USGS Publications Warehouse

    Berg, R.C.

    1984-01-01

    A beach ridge and dune complex with good radiocarbon control sampling the last 3500 radiocarbon years B.P. provides new insights on the early genesis of clay bands in sandy soils. Soil profiles were sampled by age groups, described in the field, and then subjected to laboratory analyses for particle-size distribution, pH, organic carbon, carbonate minerals, and extractable iron and manganese. This study suggests that small increases in pH, brought about by small increases in carbonate content within the soil profile, are responsible for flocculating small amounts of illuviated clay. This process, along with a transition to a greater hydraulic conductivity with soil depth due to coarser textures in any given profile, partly explains the existence and possible reason for the initiation of illuvial zones and eventually for clay-band horizons. A pronounced increase in the thickness of incipient clay-band horizons in soils older than 2300 years appears due to finer textures in the parent materials than are present in younger soils. Because of slightly reduced porosity and lower permeability, carbonates and a high pH are retained in both illuvial and eluvial horizons of some of these older soils. In addition, only in those profiles older than 2300 years do clay and iron oxide concentrations coincide and is there some suggestion of greater amounts of extractable manganese in horizons of minimum iron and clay. A pronounced segregation of clay-iron bands is not apparent at the study area but should occur in future years as additional amounts of iron and clay are deposited. ?? 1984.

  17. Interfacial reactions between humic-like substances and lateritic clay: application to the preparation of "geomimetic" materials.

    PubMed

    Goure-Doubi, Herve; Martias, Céline; Lecomte-Nana, Gisèle Laure; Nait-Ali, Benoît; Smith, Agnès; Thune, Elsa; Villandier, Nicolas; Gloaguen, Vincent; Soubrand, Marilyne; Konan, Léon koffi

    2014-11-15

    The aim of this study was to understand the mechanisms responsible for the strengthening of "geomimetic" materials, especially the chemical bonding between clay and humic substances. The mineral matter is lateritic clay which mainly consists in kaolinite, goethite, hematite and quartz. The other starting products are fulvic acid (FA) and lime. The preparation of these geomimetic materials is inspired from the natural stabilization of soils by humic substances occurring over thousands of years. The present process involves acidic and alkaline reactions followed by a curing period of 18days at 60°C under a water saturated atmosphere. The acceleration of the strengthening process usually observed in soils makes this an original process for treatment of soils. The consolidation of the "geomimetic" materials could result from two major phenomena: (i) chemical bonding at the interface between the clay particles and iron compounds and the functional groups of the fulvic acid, (ii) a partial dissolution of the clay grains followed by the precipitation of the cementitious phases, namely calcium silicate hydrates, calcium aluminate hydrates and mixed calcium silicum and aluminum hydrates. Indeed, the decrease of the BET specific area of the lateritic clay after 24 h of reaction with FA added to the structural reorganization observed between 900 and 1000°C in the "geomimetic" material, and to the results of adsorption measurements, confirm the formation of organo-ferric complexes. The presence of iron oxides in clay, in the form of goethite, appears to be another parameter in favor of a ligand exchange process and the creation of binding bridges between FA and the mineral matter. Indeed all faces of goethite are likely to be involved in complexation reactions whereas in lateritic clay only lateral faces could be involved. The results of the adsorption experiments realized at a local scale will improve our understandings about the process of adsorption of FA on lateritic

  18. Speciation of uranium in surface-modified, hydrothermally treated, (UO{sub 2}){sup 2+}-exchanged smectite clays

    SciTech Connect

    Giaquinta, D.M.; Soderholm, L.; Yuchs, S.E.; Wasserman, S.R.

    1997-08-01

    A successful solution to the problem of disposal and permanent storage of water soluble radioactive species must address two issues: exclusion of the radionuclides from the environment and the prevention of leaching from the storage media into the environment. Immobilization of radionuclides in clay minerals has been studied. In addition to the use of clays as potential waste forms, information about the interactions of radionuclides with clays and how such interactions affect their speciations is crucial for successful modeling of actinide-migration. X-ray absorption spectroscopy (XAS) is used to determine the uranium speciation in exchanged and surface-modified clays. The XAS data from uranyl-loaded bentonite clay are compared with those obtained after the particle surfaces have been coated with alkylsilanes. These silane films, which render the surface of the clay hydrophobic, are added in order to minimize the ability of external water to exchange with the water in the clay interlayer, thereby decreasing the release rate of the exchanged-uranium species. Mild hydrothermal conditions are used in an effort to mimic potential geologic conditions that may occur during long-term radioactive waste storage. The XAS spectra indicate that the uranyl monomer species remain unchanged in most samples, except in those samples that were both coated with an alkylsilane and hydrothermally treated. When the clay was coated with an organic film, formed by the acidic deposition of octadecyltrimethoxysilane, hydrothermal treatment results in the formation of aggregated uranium species in which the uranium is reduced from U{sup VI} to U{sup IV}.

  19. Clays causing adhesion with tool surfaces during mechanical tunnel driving

    NASA Astrophysics Data System (ADS)

    Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

    2009-04-01

    During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

  20. Spectral Inspections on Molecular Configurations of Nile Blue A Adsorbed on the Elementary Clay Sheets.

    PubMed

    Huang, Mei; He, Shuai; Liu, Wenhong; Yao, Yunjin; Miao, Shiding

    2015-10-22

    Studies on the configuration of dye molecules are of great importance in revealing origins of the electronic bands as well as understanding their transitions. In this work, we utilized dye molecules named Nile blue A, which are a type of oxazine dyes, to study the molecular configurations when they are transferred from solutions to a solid surface. The Langmuir-Blodgett (LB) technique was employed to construct such an interface where the interaction between the dye molecules and solid supports can be pursued. Hybrid films were prepared via the LB depositions, and the dye molecules were assembled on the elementary clay sheets (laponite, saponite). The configuration of Nb reflected by the molecular orientation, packing density, phase behavior, and variances of the surface tension has been derived. The ex situ spectroscopy characterizations such as UV-vis absorption, fluorescence emission, and excitation spectra were carried out on these LB films to reveal the fact that the adsorbed Nb molecules are mainly assembled in two types of configurations. Adsorbed state I was found to be achieved at high concentrations (1-10 ppm) of clay dispersions and low surface pressure (∼5 mN/m). In this state the anionic oxazine rings of Nb are adsorbed on clay sheets sharing a large lift-off area. This configuration gives allowable fluorescence (λ = 550 nm). Lower clay concentration (<1 ppm) and high surface pressure (10-30 mN/m) yield the adsorbed state II in which the oxazine chromophores were arranged in a side-by-side style, and the dye molecules stand perpendicularly to the clay sheets. This conformation exhibits no photoluminescence. PMID:26436823

  1. Coatings and films derived from clay/wax nanocomposites

    DOEpatents

    Chaiko, David J.; Leyva, Argentina A.

    2006-11-14

    The invention provides methods for making clay/wax nanocomposites and coatings and films of same with improved chemical resistance and gas barrier properties. The invention further provides methods for making and using emulsions of such clay/wax nanocomposites. Typically, an organophillic clay is combined with a wax or wax/polymer blend such that the cohesion energy of the clay matches that of the wax or wax/polymer blend. Suitable organophilic clays include mica and phyllosilicates that have been surface-treated with edge or edge and surface modifying agents. The resulting nanocomposites have applications as industrial coatings and in protective packaging.

  2. Chemical disaggregation of kaolinitic claystones (tonsteins and flint clays)

    USGS Publications Warehouse

    Triplehorn, D.M.; Bohor, B.F.; Betterton, W.J.

    2002-01-01

    The coarse, non-clay fraction of many flint-like kaolinitic claystones often contains mineral grains diagnostic of the claystone's origin and, in the case of tonsteins (altered volcanic ashes), may also provide minerals suitable for radiometric dating. Separation of the non-clay mineral fraction is often difficult because flint clays and flint-like clays resist slaking in water and thus are difficult to disaggregate. Chemical disaggregation of resistant kaolinitic claystones may be achieved by immersion in either hydrazine monohydrate or DMSO for periods ranging from one day to several weeks. Generally, hydrazine monohydrate works more quickly and efficiently than DMSO to disaggregate most kaolinitic claystones and flint clays.

  3. Load Dependence of Ultrasonic Velocities for Sand and Sand/Clay Mixtures

    NASA Astrophysics Data System (ADS)

    Toffelmier, D. A.; Dufrane, W. L.; Aracne-Ruddle, C. M.; Bonner, B. P.; Berge, P. A.; Viani, B. E.; Knauss, K. G.

    2001-12-01

    Ultrasonic velocities increase rapidly when a load is first applied to a granular material, as contact area and coordination number of grain contacts increase. Porosity, grain size, grain shape, and mineralogy all play a role in determining this nonlinear response. We adapted the ultrasonic pulse transmission method to measure compressional (P) and shear (S) wave velocities at ultrasonic frequencies (100-500 kHz) for lightly loaded artificial soils (to 0.1 MPa maximum). Samples were fabricated from Ottawa sand mixed with a swelling clay (Gonzales County, Texas, Ca-montmorillonite). The clay was equilibrated with 100% RH air to control water content. The clay made up 1, 3, 5, 10% of the samples by mass. Clay particles were examined using the Atomic Force Microscope (AFM) in order to determine grain size and morphology. AFM images showed platy morphology and a broad distribution of grain size. Our measurements show that the sample of pure sand (Ottawa F-50) shows a cubic relationship between stress and compressional wave velocity. Pure sand follows the Hertz contact theory incorporating grain roughness. The samples with Ca-montmorillonite had properties that were very different and unexpected. The compressional wave velocities for these samples are nearly independent of pressure below 0.1 MPa. Even the sample with 1% clay does not have the strong nonlinear behavior shown by the Hertz contact theory. The compressional wave velocity was highest in the 1% clay sample (708 m/s at 0.07MPa), the 10% clay sample had a slightly lower velocity (700 m/s at 0.07MPa), and the 3% clay sample had a much lower velocity (478 m/s at 0.07MPa). This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48 and supported specifically by the Environmental Management Science Program of the Office of Environmental Management and the Office of Science. >http://www.llnl.gov/ees/esd/expgeoph/Berge/EMSP/

  4. Advanced clay nanocomposites based on in situ photopolymerization utilizing novel polymerizable organoclays

    NASA Astrophysics Data System (ADS)

    Kim, Soon Ki

    Polymer nanocomposite technology has had significant impact on material design. With the environmental advantages of photopolymerization, a research has recently focused on producing nanocomposites utilizing inexpensive clay particles based on in situ photopolymerization. In this research, novel polymerizable organoclays and thiol-ene photopolymerization have been utilized to develop advanced photopolymer clay nanocomposites and to overcome several limitations in conventional free radical photopolymers. To this end, factors important in nanocomposite processes such as monomer composition, clay dispersion, and photopolymerization behavior in combination with the evolution of ultimate nanocomposite properties have been investigated. For monomer-organoclay compositions, higher chemical compatibility of components induces enhanced clay exfoliation, resulting in photopolymerization rate increases due to an amplified clay template effect. Additionally, by affecting the stoichiometric ratio between thiol and acrylate double bond in the clay gallery, thiolated organoclays enhance thiol-ene copolymerization with increased final thiol conversion while acrylated organoclays encourage acrylate homopolymerization. In accordance with the reaction behavior, incorporation of thiolated organoclays makes polymer chains more flexible with decreased glass transition temperature due to higher formation of thio-ether linkages while adding acrylated organoclays significantly increases the modulus. Photopolymer nanocomposites also help overcome two major drawbacks in conventional free radical photopolymerization, namely severe polymerization shrinkage and oxygen inhibition during polymerization. With addition of a low level of thiol monomers, the oxygen inhibition in various acrylate systems can be overcome by addition of only 5wt% thiolated organoclay. The same amount of polymerizable organoclay also induces up to 90% decreases in the shrinkage stress for acrylate or thiol

  5. Photochemical Deposition of Silver Nanoparticles on Clays and Exploring Their Antibacterial Activity.

    PubMed

    Lombardo, Patrícia C; Poli, Alessandra L; Castro, Lucas F; Perussi, Janice R; Schmitt, Carla C

    2016-08-24

    Photochemical method was used to synthesize silver nanoparticles (AgNPs) in the presence of citrate or clay (SWy-1, SYn-1, and Laponite B) as stabilizers and Lucirin TPO as photoinitiator. During the photochemical synthesis, an appearance of the plasmon absorption band was seen around 400 nm, indicating the formation of AgNPs. X-ray diffraction results suggested that AgNPs prepared in SWy-1 were adsorbed into interlamellar space, and moreover, showed some clay exfoliation. In the case of SYn-1, AgNPs was not intercalated. For the AgNP/Lap B sample, the formation of an exfoliated structure occurred. Transmission electron microscopy revealed the spherical shape of AgNPs for all samples. The particle sizes obtained for AgNP/SWy-1, AgNP/SYn-1, and AgNP/Lap B were 2.6, 5.1, and 3.8 nm, respectively. AgNPs adsorbed on SYn-1 reveal nonuniform size and aggregation of some particles. However, AgNP/SWy-1 and AgNP/Lap B samples are more uniform and have diameters smaller than those prepared with SYn-1. This behavior is due to the ability to exfoliate these clays. The antibacterial activities of pure clays, AgNP/citrate, and AgNP/clays were investigated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). AgNPs in the presence of clays (AgNPs/SYn-1 and AgNPs/SWy-1) showed a lower survival index percentage compared to those obtained for pure clays and AgNPs. The AgNP/SWy-1 sample showed good antibacterial activity against both tested species and the lowest survival index of 3.9 and 4.3 against E. coli and S. aureus, respectively. AgNPs are located in the interlayer region of the SWy-1, which has acid sites. These acidic sites may contribute to the release of Ag(+) ions from the surface of AgNPs. On the other hand, Laponite B and AgNP/Lap B samples did not demonstrate any bactericidal activity. PMID:27487246

  6. Relevance of magnetic properties for the characterisation of burnt clays and archaeological tiles

    NASA Astrophysics Data System (ADS)

    Beatrice, C.; Coïsson, M.; Ferrara, E.; Olivetti, E. S.

    The archaeomagnetism of pottery, bricks and tiles is typically employed for dating inferences, yet the magnetic properties of ancient ceramics can also be convenient for their characterisation, to evaluate the technological conditions applied for their production (temperature, atmosphere, and duration of firing), as well as to distinguish groups of sherds having different provenance. In this work, the measurement of hysteresis loops has been applied and combined with colour survey to characterise the magnetic properties of burnt clays and archaeological tiles. Four calcareous and non-calcareous clays, along with seventeen tile fragments excavated from the sites of the ancient Roman towns of Pompeii and Gravina di Puglia, in Southern Italy, are examined. The ferrimagnetic character of the clays, in general, enhances with increasing firing temperatures until vitrification processes occur (900-1000 °C) dissolving iron oxides and dispersing the colour and magnetic properties they provide. High values of saturation magnetization are observed in clays with relevant calcareous content after firing above 900 °C, which results in the formation of Ca-silicates able to delay the onset of the vitrification processes. Magnetic properties of the tiles have been evaluated in terms of the high coercivity (i.e. mainly ferrimagnetic) or low coercivity behaviour (i.e. including relevant paramagnetic and superparamagnetic contributions). Enhanced ferrimagnetic character, mostly depending on the growth in number and volume of iron oxide particles, is associated with the development of an intense reddish hue.

  7. Clay Mineralogy of Shallow Core Sediments of Lake Acigöl, Denizli, Turkey

    NASA Astrophysics Data System (ADS)

    Budakoglu, Murat; Karaman, Muhittin; Geredeli, Serpil; Unal, Hatice; Abdelnasser, Amr; Kiran Yildirim, Demet

    2014-05-01

    Lake Acıgöl is a hypersaline and active industrial salt production lake located in Denizli, Turkey. Lake Acıgöl has been investigated to elucidate the distribution clay minerals under the saline conditions of the lake and carbonate and ophiolitic rocks controlled lake basin. The lake is very shallow and generally characterized by an un-stratified and whole oxygenated water table. Determination clay minerals in the bulk samples via XRD method was not possible due to the their small amount. Therefore, the sequential clay enrichment procedure applied to the bulk samples such as sample dispersion, removal of soluble salts and ions, and particle-size fractionation. The XRD analyses of normal, glycolated and heat-treated shallow core samples show that the dominant clay minerals in the samples to be illite, including the swelling montmorillonite and kaolinite minerals are encountered less frequently. Glauberite, Blodite, Dansite and Nickelblodite have been also identified as soda minerals by XRD studies.

  8. Effect of electrolytes on the microstructure and yielding of aqueous dispersions of colloidal clay.

    PubMed

    Ali, Samim; Bandyopadhyay, Ranjini

    2016-01-14

    Na-montmorillonite is a natural clay mineral and is available in abundance in nature. The aqueous dispersions of charged and anisotropic platelets of this mineral exhibit non-ergodic kinetically arrested states ranging from soft glassy phases dominated by interparticle repulsions to colloidal gels stabilized by salt induced attractive interactions. When the salt concentration in the dispersing medium is varied systematically, viscoelasticity and yield stress of the dispersion show non-monotonic behavior at a critical salt concentration, thus signifying a morphological change in the dispersion microstructures. We directly visualize the microscopic structures of these kinetically arrested phases using cryogenic scanning electron microscopy. We observe the existence of honeycomb-like network morphologies for a wide range of salt concentrations. The transition of the gel morphology, dominated by overlapping coin (OC) and house of cards (HoC) associations of clay particles at low salt concentrations to a new network structure dominated by face-face coagulation of platelets, is observed across the critical salt concentration. We further assess the stability of these gels under gravity using electroacoustics. This study, performed for concentrated clay dispersions for a wide concentration range of externally added salt, is useful in our understanding of many geophysical phenomena that involve the salt induced aggregation of natural clay minerals. PMID:26477340

  9. Nonspecific Compatibilization of Polymer Blends Using Functionalized Clays

    NASA Astrophysics Data System (ADS)

    Fisher, Robert; Goldman, Michael; Rubinstein, Michael; Si, Mayu; Sokolov, Jonathan; Rafailovich, Miriam; Ruderman, Gregory

    2003-03-01

    Binary and tertiary blends of polystyrene (PS), polymethylmethacrylate (PMMA) , and poletheylene terephthalate (PET) were produced by melt mixing in a Brabender twin screw extruder at 100RPM, 180C . Ten weight percent Cloisite 20A clay (Southern Clay Corp) was then added to some of the mixtures after ten minutes. In one case the clay was fist melt mixed with all three polymer components separately and then the three polymer/clay composites were melt mixed together. The samples were examined with transmission electron microscopy which revealed that the addition of clay during melt mixing produced a material that was much more homogenous than the material without clay or where the clay was first mixed individually into the components. This was confirmed by DMA analysis where the melt mixed sample with clay exhibited only one glass transition for both binary and tertiary blends, whereas the sample without clay, or where clay was first mixed into the individual components showed two glass transitions. These results were interpreted in terms of an in situ grafting model where the large surface to volume ration of the clay platelets was able to drastically reduce interfacial tension and hence domain size in the blends.

  10. Dioxins in primary kaolin and secondary kaolinitic clays.

    PubMed

    Schmitz, Martin; Scheeder, Georg; Bernau, Sarah; Dohrmann, Reiner; Germann, Klaus

    2011-01-15

    Since 1996 dioxins have been repeatedly detected worldwide in Tertiary ball clays used as anticaking agent in the production of animal feed and a variety of other applications. The dioxins of these natural clays are very unlikely of anthropogenic source, but no model of dioxin enrichment has been established. A hypothetical model is presented which explains the highly variable dioxin loadings of the Tertiary kaolinitic clays by natural addition during clay-sedimentation. To prove this hypothesis, Tertiary primary nonsedimentary kaolin and sedimentary kaolinitic clays were collected at three profiles in Europe and analyzed for mineralogy, chemistry, organic carbon, and polychlorinated dibenzo-p-dioxins/-furans (PCDD/F). Primary kaolin, kaolinitic, and lignitic clays contained almost no PCDFs. PCDD concentration differed markedly between primary kaolin (3-91 pg/g) and secondary kaolinitic clay (711-45935 pg/g), respectively, lignitic clays (13513-1191120 pg/g). The dioxin loading of secondary kaolinitic and lignitic clays is approximately 10 to a few thousand times higher than in the primary kaolin or recent environmental settings. The dioxin concentrations decrease from octachlorodibenzo-p-dioxin to the tetrachlorodibenzo-p-dioxins and exhibit the "natural formation pattern". No correlation between PCDD/F concentration and bulk composition of clays was found. These findings support the hypothesis of the enrichment of dioxin in clays during sedimentation. PMID:21126071

  11. Characterization and adsorptive properties of pharmaceutical grade clays.

    PubMed

    Browne, J E; Feldkamp, J R; White, J L; Hem, S L

    1980-07-01

    The adsorption of tetracycline by clays commonly used in pharmacy can be predicted if the identity and character of the commerical clay sample are established. X-ray diffraction. IR spectroscopy, and chemical analysis were used to identify the clay component and any nonclay diluents present in a series of commerical pharmaceutical grade clays. The major clay components were montmorillonite, hectorite, attapulgite, saponite, and kaolinite. The clay structure, the nature of the exchangeable cation, and the presence of nonclay components are important factors affecting the tetracycline-clay interaction. In general, clay structures with a high surface charge lead to a greater interaction with the protonated form of tetracycline, while interaction with the zwitterionic form of tetracycline occurs in clay structures with minimal surface charge. The presence of multivalent, exchangeable cations on the clay surface diminishes interaction with the protonated form of tetracycline. Nonclay components such as calcite and dolomite increase the interactions of the zwitterionic and anionic forms of tetracycline with the clay. PMID:7391947

  12. Synchrotron texture analysis of clay-rich sediments from the Nankai trench and accretionary prism

    NASA Astrophysics Data System (ADS)

    Schumann, Kai; Stipp, Michael; Leiss, Bernd; Behrmann, Jan-Hinrich

    2013-04-01

    Synchrotron diffraction is the most suitable tool for fast multi-mineral phase texture analysis of water-containing clay rich sediment samples due to short wavelengths (in the range of 0.12 Å), high energy radiation and a resulting mm- to cm-scale sample penetration. We carried out synchrotron texture analysis on a sample set from the Nankai trench and accretionary prism offshore Japan. Samples were encountered by IODP Expeditions 315, 316 and 333 of the NanTroSEIZE project from a depth range between 25 mbsf (meters below seafloor) and 522 mbsf. The accretionary prism sediments have a relatively uniform composition of approximately 40% clay minerals, 25% quartz, 25% feldspar, and up to 10% calcite. A first sample set analyzed was taken as recovered from drilling; a second sample set was additionally experimentally deformed in a triaxial deformation apparatus up to axial strains of 60%. Measurements were carried out at DESY (German Electron Synchrotron source) in Hamburg. In order to measure complete pole figures sample cylinders of 2 cm in diameter and 2 cm in length were measured in a phi angle-range from -90 to +90° in 5° steps. Rietveld refinement results using the MAUD program package show that the composition of the IODP Expedition 333 samples from the incoming plate differs slightly from the relatively uniform IODP Expedition 315 and 316 samples of the accretionary prism. They contain ~35% clay minerals, ~30% quartz and ~35% feldspar. For IODP Expedition 315 and 316 samples the Rietveld refinement results correspond to the standard XRD data. The synchrotron texture results of the recovered samples without experimental deformation show an increasingly strong preferred orientation of the clay minerals with increasing sediment depth for the incoming plate. Interestingly, also feldspar shows a significant texture, which is likely due to a shape fabric of the grains. The sediment texture can be explained by compaction and porosity reduction with increasing

  13. Clay mineral type effect on bacterial enteropathogen survival in soil.

    PubMed

    Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific. PMID:24035982

  14. Clay mineral formation and transformation in rocks and soils

    USGS Publications Warehouse

    Eberl, D.D.

    1983-01-01

    Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favoring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again. Refs.

  15. Sonochemical intercalation of preformed gold nanoparticles into multilayered clays.

    PubMed

    Belova, Valentina; Möhwald, Helmuth; Shchukin, Dmitry G

    2008-09-01

    Multilayered Na (+)-montmorillonite clays intercalated with Au nanoparticles were synthesized by direct ultrasonic impregnation of preformed gold colloid into the clay matrix. The sonicated composite product then consists of Au nanoparticles homogeneously dispersed in the clay. The resulting clay/nano-Au composite was calcined at 800 degrees C and characterized by BET surface area analysis, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared measurements. Nearly spherical-shaped gold nanoparticles, with a size of 6 +/- 0.5 nm, are located in the pores of clay calcined at 800 degrees C. Their nanocomposites are thermally stable as was shown by thermogravimetric analysis. No aggregation of the gold nanoparticles was observed during calcination. The proposed ultrasonic intercalation approach is an universal one and can be employed for synthesis of catalytically active metal-clay nanocomposites stable at high temperatures with high dispersability of the metal nanoparticles in the clay matrix. PMID:18652497

  16. CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.

    USGS Publications Warehouse

    Bodine, Marc W., Jr.

    1985-01-01

    Insoluble residues from three sequences of Paleozoic marine evaporites (Retsof salt bed in western New York, Salado Formation in south-eastern New Mexico, and Paradox Member of the Hermosa Formation in southeastern Utah) are rich in trioctahedral clays. Chlorite (clinochlore), corrensite (mixed-layer chlorite-trioctahedral smectite), talc, and illite (the only dioctahedral clay) are the dominant clay minerals; serpentine, discrete trioctahedral smectite (saponite), and interstratified talc-trioctahedral smectite are sporadically abundant. These clay-mineral assemblages differ chemically and mineralogically from those observed in most continental and normal marine rocks, which commonly contain kaolinite, dioctahedral smectite (beidellite-montmorillonite), illite, mixed-layer illite-dioctahedral smectite, and, in most cases, no more than minor quantities of trioctahedral clay minerals. The distinctive clay mineralogy in these evaporite sequences suggests a largely authigenic origin. These clay minerals are thought to have formed during deposition and early diagenesis through interaction between argillaceous detritus and Mg-rich marine evaporite brines.

  17. Feasibility of classification of clay minerals by using PAS

    NASA Astrophysics Data System (ADS)

    Honda, Y.; Yoshida, Y.; Akiyama, Y.; Nishijima, S.

    2015-06-01

    After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found.

  18. Selecting brines and clay stabilizers to prevent formation damage

    SciTech Connect

    Evans, B.; Ali, S.

    1997-05-01

    Although many technical reports have been written about formation damage caused by brine/formation interactions, this article discusses the effects brines and chemical clay stabilizers have on pure samples of kaolinite, smectite, illite and chlorite clays. Analytical chemistry and geochemical models were not employed in this study; instead, capillary suction time tests were used to empirically compare clay migration and swelling characteristics when samples were exposed to certain brine/clay stabilizer combinations. Objective of the study was to determine which type of clay was most damaging in reservoir rocks, and whether one brine or chemical stabilizer could meet the needs of stabilizing all clay types. This information is provided with well completion operations in mind, especially when fluid cost/performance is a major concern. This article compares the unique brine/chemical stabilizer reaction characteristics of each clay type common to oil and gas reservoirs.

  19. Freezing D2O clay gels.

    PubMed

    Letellier, M

    1998-01-01

    To obtain the T1 surface value in smectites/D2O diluted suspensions or gels, as was obtained on a monolayer deuterated clay, we freeze them. The broad Pake's doublets similar to ice doublets and with the same T1 show that we can separate frozen from unfrozen D2O. The latter exhibits a narrower line and a single T1 and is attributed to the liquid surface water layer in rapid exchange with the nearby supercooled water, the quantity of which diminishes with the lowering of the temperature depending on the gel porosity. It is possible to measure the supercooled water quantity and to correct the T1 measured values to extract the T1 surface. The value extrapolated at room temperature allows the complete clay surface area measurement. The example of a montmorillonite is given and a comparison with laponite is made. PMID:9803898

  20. Clay-based geothermal drilling fluids

    SciTech Connect

    Guven, N.; Carney, L.L.; Lee, L.J.; Bernhard, R.P.

    1982-11-01

    The rheological properties of fluids based on fibrous clays such as sepiolite and attapulgite have been systematically examined under conditions similar to those of geothermal wells, i.e. at elevated temperatures and pressures in environments with concentrated brines. Attapulgite- and sepiolite-based fluids have been autoclaved at temperatures in the range from 70 to 800/sup 0/F with the addition of chlorides and hydroxides of Na, K, Ca, and Mg. The rheological properties (apparent and plastic viscosity, fluid loss, gel strength, yield point, and cake thickness) of the autoclaved fluids have been studied and correlated with the chemical and physical changes that occur in the clay minerals during the autoclaving process.

  1. Organically modified clay removes oil from water

    SciTech Connect

    Alther, G.R.

    1995-12-31

    When bentonite or other clays and zeolites are modified with quaternary amines, they become organophilic. Such modified bentonites are used to remove mechanically emulsified oil and grease, and other sparingly soluble organics. If the organoclay is granulated, it is placed into a liquid phase carbon filter vessel to remove FOG`s and chlorinated hydrocarbons. In this application the clay is mixed with anthrazite to prevent early plugging of the filter by oil or grease droplets. In batch systems a powered organoclay is employed. Types of oil found in water can include fats, lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oil, diesel oils; and light hydrocarbons such as kerosene, jet fuel, and gasoline.

  2. Humidity Dependent Extinction of Clay Aerosols

    NASA Astrophysics Data System (ADS)

    Greenslade, M. E.; Attwood, A. R.

    2010-12-01

    Aerosols play an important role in the Earth’s radiative balance by directly scattering and absorbing radiation. The magnitude of aerosol forcing can be altered by changes in relative humidity which cause aerosol size, shape and refractive index to vary. To quantify these effects, a custom cavity ring down instrument operated at 532 nm with two sample channels measures aerosols extinction under dry conditions and at elevated humidity. The optical growth, fRH(ext), is determined as a ratio of the extinction cross section at high relative humidity to that under dry conditions. Three key clay components of mineral dust and mixtures of clay components with ammonium sulfate are investigated using this method. Experimentally obtained optical growth is compared with physical growth factors from the literature and our work determined using several different techniques. Further, Mie theory calculations based on published optical constants are compared with experimental results. Differences between theory and experiment will be discussed.

  3. Nuclear Orientation of IRON-59.

    NASA Astrophysics Data System (ADS)

    Kravitz, Philip Scott

    A nuclear orientation study of Fe('59) has been performed utilizing a He('3)/He('4) dilution refrigerator. Extensive studies of the directional distribution of beta particles and gamma rays has yielded a measurement of the Fermi to Gamow-Teller mixing ratio, y = (C(,V)M(,F))/(C(,A)M(,GT)), for the isospin-hindered 475 keV (beta) decay and an upper limit on the nuclear magnetic moment of Fe('59). The iron nuclei were oriented in a thin permendur foil at ultralow temperatures (10('-2)(DEGREES)K). The nuclear orientation system employed has excellent long term temperature stability and allowed for the measurement of the beta particles at two angles with respect to the nuclear orientation axis, through the application of magnetizing fields, with minimal deflections from their original trajectories. After all corrections, the experimental beta-particle asymmetry was found to be in agreement with the theoretical expectations over a sizable energy range. Including all estimated systemmatic errors, the beta-particle asymmetry parameter for the 475 keV (,(beta))-decay of Fe('59), A(,(beta)), was determined to be A(,(beta)) = -0.259 (+OR-) 0.061 yielding a corresponding value of y = -0.090 (+OR-) 0.039 which is in agreement with previous measurements. Analysis of the 192 kev, 1099 kev, and 1292 kev (gamma)-ray photopeaks of Fe('59) impose an upper limit of (VBAR)(mu)(Fe('59))(VBAR) < 0.36(mu)(,N) for the nuclear magnetic moment of Fe('59) also in substantial agreement with the most recent measurement.

  4. Application of modulus degradation model of clays.

    USGS Publications Warehouse

    Chen, A.T.F.

    1982-01-01

    A degradation model is applied in conjunction with different soil models and stress-strain relations to site response analyses during earthquakes. To evaluate the effects of degradation, computations on two clay deposits subjected to both high and low-level input excitations are conducted. Where surface response differs, the use of degradation with strength reduction is less conservative when compared to the use of degradation without strength reduction.- from ASCE Publications Abstracts

  5. Electrically induced reduction of trichloroethene in clay.

    PubMed

    Jin, Song; Fallgren, Paul H

    2010-01-15

    Chlorinated compounds such as trichloroethene (TCE) are recalcitrant contaminants commonly detected in soil and groundwater. Contemporary remedies such as electron donor amendment tend to be less or ineffective in treating chlorinated compounds in matrix of lower permeability, such as clay. In this study, electrically induced reduction (EIR) was tested by inserting electrodes in saturated clay containing 122.49-125.43 mg TCE kg(-1). Weak electric potentials (E) of 6, 9, and 12 V m(-1) were applied, and up to 97% of TCE were depleted during the study period. Corresponding increases in chloride concentrations was observed during TCE depletion, indicating a reductive dechlorination pathway. No migration of TCE was observed between the two electrodes, neither were intermediate compounds such as dichloroethene (DCE) or vinyl chloride (VC). Results were also tested against a mathematical equation we previously established for field applications. Electrically induced reduction may offer a novel method for in situ degradation of chlorinated contaminants, especially in low-permeable media such as clay. PMID:19729244

  6. Electrokinetics of pure clay minerals revisited

    SciTech Connect

    Sondi, I.; Biscan, J.; Pravdic, V.

    1996-03-25

    Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advance in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater. Three of the most important clay minerals encountered in suspended matter in natural waters, montmorillonite, illite, and chlorite, were prepared in a very pure state. Electrokinetic experiments were done in pure aqueous single and complex electrolyte solutions and in solutions in which natural organic matter was simulated using a humic substance, fulvic acid, of defined provenance and properties, typical of riverine waters. An isoelectric point was found at pH 5.0 {+-} 0.2 for chlorite; none were found for illite and montmorillonite. Only Ca{sup 2+} showed a charging effect on chlorite, indeed a reversal of sign from negative to positive at 1 {times} 10{sup {minus}3} mol dm{sup {minus}3}. Addition of fulvic acid affected only chlorite, illite less, and Na montmorillonite not at all.

  7. Role of bentonite clays on cell growth.

    PubMed

    Cervini-Silva, Javiera; Ramírez-Apan, María Teresa; Kaufhold, Stephan; Ufer, Kristian; Palacios, Eduardo; Montoya, Ascención

    2016-04-01

    Bentonites, naturally occurring clays, are produced industrially because of their adsorbent capacity but little is known about their effects on human health. This manuscript reports on the effect of bentonites on cell growth behaviour. Bentonites collected from India (Bent-India), Hungary (Bent-Hungary), Argentina (Bent-Argentina), and Indonesia (Bent-Indonesia) were studied. All four bentonites were screened in-vitro against two human cancer cell lines [U251 (central nervous system, glioblastoma) and SKLU-1 (lung adenocarcinoma)] supplied by the National Cancer Institute (USA). Bentonites induced growth inhibition in the presence of U251 cells, and growth increment in the presence of SKLU-1 cells, showing that interactions between bentonite and cell surfaces were highly specific. The proliferation response for U251 cells was explained because clay surfaces controlled the levels of metabolic growth components, thereby inhibiting the development of high-grade gliomas, particularly primary glioblastomas. On the other hand, the proliferation response for SKLU-1 was explained by an exacerbated growth favoured by swelling, and concomitant accumulation of solutes, and their hydration and transformation via clay-surface mediated reactions. PMID:26849195

  8. Anaerobic degradation of DCM diffusing through clay

    SciTech Connect

    Rowe, R.K.; Hrapovic, L.; Kosaric, N.; Cullimore, D.R.

    1997-12-01

    Two series of diffusion tests were performed to examine the degradation of dichloromethane (DCM) as it diffuses through clay. The first series showed the use of a synthetic leachate with no significant initial bacterial population diffusing through a plug of intact clay; there was an induction period of 95--135 d, during which diffusion was as expected in the absence of degradation, followed by a second stage, where degradation occurred with an apparent half-life of less than 55 d at a temperature of 24 C. The second series of tests examined the diffusion of an actual leachate from the Keele Valley Landfill (KVL) (which provided both nutrients and a source of bacteria), through a compacted clay. In these tests, the induction period was reduced to 40--60 d, after which the apparent half-life was 20 d or less at 27 C. The diffusion coefficient for DCM was approximately 8 {times} 10{sup {minus}10} m{sup 2}/s, with partitioning coefficient K{sub d} = 1.5 cm{sup 3}/g. Biological activity was confirmed by evaluating the change in the concentration of adenosine-5-triphosphate and the biological activity reaction test (BART). The degradation of DCM did not produce any detectable levels of chloromethane.

  9. Clay mineralogy of Atokan Formation from the north western shelf basin, Eddy County, New Mexico

    SciTech Connect

    Sivalingam, S. )

    1993-03-01

    The typical clay minerals in the Atokan shales consists of randomly mixed illite/smectite (I/S) layers with minor amounts of kaolinite, chlorite and illite. However, in the sandstones authigenic kaolinite and Fe-rich chlorites are the predominant clay type. The illite/smectite mixed layers are composed of a mixture of R0 and R1 types with about 40% to 65% illite. The majority of the negative charges in the I/S particles are due to Al substitution for Si in the tetrahedra. The octahedral population is dominated by Al, ranging from 1.76 to 1.71 ions, the remainder of the octahedra is filled by Mg and Fe. Interlayer K ranges from 0.32 to 0.42 ions. The cation exchange capacity (CEC) of shales ranges from 30 to 50 meq/100 gm. Shales with the highest amount of total clays showed the highest CEC. Under transmission electron microscopy, the clay particles occur as surrounded lamellar aggregates with some early stages of discrete domain formation and overgrowths. High resolution lattice images of the I/S mixed layers appear as wavy, anastomising layers. Edge dislocations are common and lattice thickness ranges from 10.08[angstrom] to 30[angstrom], indicating the existence of a wide range of mixed layering. Some discrete packets of illite are observed within the stacks of I/S layers. Electron diffraction patterns observed from the I/S particles showed a combination of continuous and semi-continuous rings, spots and arced patterns, indicating turbostratic stacking sequence.

  10. Cracking dynamics and morphology of desiccating clay overlying a granular substrate

    NASA Astrophysics Data System (ADS)

    DeCarlo, K.; Shokri, N.

    2012-12-01

    Desiccation cracks are a common phenomenon present in many environmental, hydrological and engineering applications, including soil physics, where they act as preferential pathways for transport processes; and geotechnical engineering, where they compromise the structural stability of buildings and waste containment facilities. Thus better understanding of its physics and dynamics has many applications. We conducted a comprehensive investigation to delineate the effects of a discrete and discontinuous substrate on the cracking dynamics, patterns and morphology of an overlying thin layer of clay. Square glass containers (40x40x2.5 cm3) packed with a thin layer of kaolinite clay overlying seven types of a silica sand substrate differing in particle size distribution were used in our laboratory experiments. Both layers were saturated with water. The container was mounted on a digital balance to record the evaporation rate, and an automatic imaging system was used to record the general dynamics and patterns of cracking on the evaporating surface with a 5 second time interval. Images were then used to quantify crack dynamics, propagation velocities and patterns as a function of substrate texture. Results indicate an increasing crack density and smaller characteristic crack length with decreasing substrate particle size, attributed to the decreased coefficient of friction of the underlying wet sand with increasing particle size. Additionally, our results suggest that the onset and propagation of the earliest cracks are closely related to the saturation and stress gradients of the desiccating clay surface, with initially high velocities that decay to small but non-zero values as they approach the saturated zones of the clay. The majority of macroscale cracking in all cases occurred within the early stages of the evaporation process. Obtained results also show that cracking duration is inversely related to the standard deviation of the particle size of each substrate, with

  11. Mechanical properties of sand, silt, and clay containing tetrahydrofuran hydrate

    USGS Publications Warehouse

    Yun, T.S.; Santamarina, C.J.; Ruppel, C.

    2007-01-01

    The mechanical behavior of hydrate-bearing sediments subjected to large strains has relevance for the stability of the seafloor and submarine slopes, drilling and coring operations, and the analysis of certain small-strain properties of these sediments (for example, seismic velocities). This study reports on the results of comprehensive axial compression triaxial tests conducted at up to 1 MPa confining pressure on sand, crushed silt, precipitated silt, and clay specimens with closely controlled concentrations of synthetic hydrate. The results show that the stress-strain behavior of hydrate-bearing sediments is a complex function of particle size, confining pressure, and hydrate concentration. The mechanical properties of hydrate-bearing sediments at low hydrate concentration (probably 50% of pore space), the behavior becomes more independent of stress because the hydrates control both stiffness and strength and possibly the dilative tendency of sediments by effectively increasing interparticle coordination, cementing particles together, and filling the pore space. The cementation contribution to the shear strength of hydrate-bearing sediments decreases with increasing specific surface of soil minerals. The lower the effective confining stress, the greater the impact of hydrate formation on normalized strength.

  12. Optimal orientation field to manufacture magnetostrictive composites with high magnetostrictive performance

    NASA Astrophysics Data System (ADS)

    Dong, Xufeng; Ou, Jinping; Guan, Xinchun; Qi, Min

    2010-11-01

    Magnetostrictive properties have relationship with the applied orientation field during the preparation of giant magnetostrictive composites. To understand the dependence of the optimal orientation field on particle volume fraction, composites with 20%, 30% and 50% particles by volume were fabricated by distributing Terfenol-D particles in an unsaturated polyester resin under various orientation fields. Their magnetostrictive properties were tested without pre-stress at room temperature. The results indicate that as the particle volume fraction increases, the optimal orientation field increases. The main reason for this phenomenon is the packing density for the composites with higher particle volume fraction is larger than that for those with lower particle content.

  13. The direct synthesis of organic-containing clays and thermal analysis of porphyrin-clay complexes

    SciTech Connect

    Carrado, K.A.; Anderson, K.B.; Grutkoski, P.S.

    1991-01-01

    Synthetic TMA-montmorillonites have now been made in conjunction with synthetic porphyrin-hectorites reported earlier. In order to help progress towards preparation of porphyrin-containing aluminosilicate clays, the thermal stability of porphyrin-clay systems has been examined in detail. Results from TGA and Py-GC-MS indicate that the porphyrin nucleus is extremely stable in the present of clay minerals. Substituents on the nucleus such as pyridinium or anilinium are, on the other hand, slightly destabilized. In addition, the presence of transition metals like Fe(III) in metalloporphyrins appears to catalyze decomposition of the porphyrin nucleus to some degree. The use of Py-GC-MS in conjunction with TGA results greatly clarified the assignment of weight loss peaks. 18 refs., 3 figs.

  14. Effects of shock metamorphism on clay mineralogy: Implications for remote sensing of martian clays

    NASA Astrophysics Data System (ADS)

    Michalski, J. R.; Glotch, T. D.; Friedlander, L.; Bish, D. L.; Sharp, T. G.; Dyar, M. D.

    2012-12-01

    One of the most important discoveries in recent exploration of Mars has been the detection of clay minerals within materials exhumed by meteor impact, which point to ancient subsurface alteration and possible habitable conditions at depth. These "crustal clays" occur within central peaks, ejecta, and uplifted rims of many large craters (Ehlmann et al., Nature 2011). The geologic context of phyllosilicates in these settings suggests that most of these deposits represent clays that formed in the subsurface and were later exhumed by impact, rather than clays that formed as a consequence of impact. Therefore, crustal clays exposed at the surface are likely to have experienced some effects of shock metamorphism and/or thermal alteration related to meteor impact. We are investigating the effects of shock metamorphism on the mineralogy of phyllosilicates in the laboratory. Purified, size-separated clay mineral samples were pressed into pellets to decrease internal porosity and were subsequently shocked using the Flat Plate Accelerator at NASA Johnson Space Center. Five minerals (nontronite, saponite, serpentine, chlorite, and kaolinite) were shocked to six pressure steps (10, 20, 25, 30, 35, and 40 GPa). The recovered, shocked samples are being analyzed by thermal infrared emission, visible/near-infrared reflectance, X-ray diffraction (XRD), Mossbauer spectroscopy, and transmission electron microscopy (TEM). Results thus far suggest that shock metamorphism has little effect on the structure or infrared signature of the clay minerals at pressures <20 GPa. One exception is the decrease in 3-D ordering in chlorite at 10 GPa, which steadily decreases until it is essentially lost at 30 GPa. At shock pressures of 20 GPa and higher, all minerals show evidence for broadening of the basal 001 reflection, indicative of progressive decrease in crystallite size. Above 30 GPa, the structures are intensely altered and by 40 GPa, most structural order is lost, based on both XRD and TEM

  15. Effective Removal of Heavy Metals from Wastewater Using Modified Clay.

    PubMed

    Song, Mun-Seon; Vijayarangamuthu, K; Han, EunJi; Jeon, Ki-Joon

    2016-05-01

    We report an economical and eco-friendly way to remove the heavy metal pollutant using modified clay. The modification of clay was done by calcining the natural clay from Kyushu region in Japan. Further, the removal efficiency for various pH and contact time was evaluated. The morphology of the clays was studied using the scanning electron microscopy (SEM). The structural and chemical analyses of modified clay were done by using X-ray diffraction (XRD), Raman spectroscopy, and Energy dispersion analysis (EDAX) to understand the properties related to the removal of heavy metal pollutant. Further, we studied the absorption efficiency of clay for various pH and contacting time using Ni polluted water. The modified clays show better removal efficiency for all pH with different saturation time. The adsorption follows pseudo-second order kinetics and the adsorption capacity of modified clay is 1.5 times larger than that of natural clay. The increase in the adsorption efficiency of modified clay was correlated to the increase in hematite phase along with increase in surface area due to surface morphological changes. PMID:27483775

  16. Adsorption of dyes using different types of clay: a review

    NASA Astrophysics Data System (ADS)

    Adeyemo, Aderonke Ajibola; Adeoye, Idowu Olatunbosun; Bello, Olugbenga Solomon

    2015-09-01

    Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.

  17. Material characterization of the clay bonded silicon carbide candle filters and ash formations in the W-APF system after 500 hours of hot gas filtration at AEP. Appendix to Advanced Particle Filter: Technical progress report No. 11, January--March 1993

    SciTech Connect

    Alvin, M.A.

    1993-04-05

    (1) After 500 hours of operation in the pressurized fluidized-bed combustion gas environment, the fibrous outer membrane along the clay bonded silicon carbide Schumacher Dia Schumalith candles remained intact. The fibrous outer membrane did not permit penetration of fines through the filter wall. (2) An approximate 10-15% loss of material strength occurred within the intact candle clay bonded silicon carbide matrix after 500 hours of exposure to the PFBC gas environment. A relatively uniform strength change resulted within the intact candles throughout the vessel (i.e., top to bottom plenums), as well as within the various cluster ring positions (i.e., outer versus inner ring candle filters). A somewhat higher loss of material strength, i.e., 25% was detected in fractured candle segments removed from the W-APF ash hopper. (3) Sulfur which is present in the pressurized fluidized-bed combustion gas system induced phase changes along the surface of the binder which coats the silicon carbide grains in the Schumacher Dia Schumalith candle filter matrix.

  18. Laboratory reflectance spectra of clay minerals mixed with Mars analog materials: Toward enabling quantitative clay abundances from Mars spectra

    NASA Astrophysics Data System (ADS)

    Roush, Ted L.; Bishop, Janice L.; Brown, Adrian J.; Blake, David F.; Bristow, Thomas F.

    2015-09-01

    Quantitative estimates of clay minerals on the martian surface, via remote sensing observations, provide constraints on activity, timing, duration, and extent of aqueous processes and the geochemical environment in martian history. We describe an analytical study to begin enabling quantitative estimates of phyllosilicates when mixed with martian analog materials. We characterize the chemistry, mineralogy, particle size distribution, and reflectance spectra of the end-member materials: saponite, montmorillonite, pyroxene, and palagonitic soil. Reflectance spectra were obtained for physical mixtures of saponite and montmorillonite with pyroxene, and saponite with palagonitic soil. We analyzed the diagnostic phyllosilicate spectral signatures in the 2.2-2.4 μm wavelength region in detail for the mixtures. This involved fitting the observed ∼2.3 or ∼2.2 μm band depth, associated with the presence of saponite and montmorillonite, respectively, as a function of the abundance of these materials in the mixtures. Based upon the band depth of the spectral features we find that 3-5 wt.% of the clay minerals in the mixture with pyroxene can be recognized and at 25 wt.% their presence is indisputable in the mixtures. When the saponite is mixed with the lower albedo palagonitic soil, its presence is clearly distinguishable via the 1.4 and 2.3 μm features at 25 wt.% abundance. These relationships, between abundance and band depth, provide an ability to quantitatively address the amount of these materials in mixtures. The trends described here provide guidance for estimating the presence of phyllosilicates in matrices on the martian surface.

  19. The impact of hazardous waste leachate on performance of clay liners.

    PubMed

    Mosavat, Nasim; Nalbantoglu, Zalihe

    2013-02-01

    Penetration of hazardous liquids through waste containment barriers exerts contamination and considerable alterations in geotechnical properties of clay liners. In general, these changes are attributed to the variation of the dielectric constant and the chemistry of the pore fluids which cause changes in soil structure. In the present study, a series of laboratory tests were performed on natural and contaminated clay soil permeated with different hazardous liquids: ethylene glycol and toluene which are generally found in petroleum-contaminated sites, possessing intermediate and low dielectric constants. Toluene was used in its pure form and ethylene glycol was used at various percentages of 0, 20, 40 and 60% by the volume of distilled water. In addition, natural sea water was also utilized as an inorganic fluid for permeation and salinization of the clay soil. The overall test results indicated that plasticity, sedimentation time, unconfined compressive strength, swell and compressibility generally decreased with increasing organic fluid/water concentration, while a slight increase in the permeability values was observed. Pure toluene resulted in diminution of plasticity and considerable flocculation of the particles which caused the soil to become granular. Sea water also caused particle flocculation and reduction in plasticity, swell potential and unconfined compressive strength, although it was noted that compressibility properties remained unchanged compared to distilled water. Finally, the correlation between the electrical resistivity and plasticity index values suggested that the electrical resistivity measurements can be used as a detecting technique for subsurface soil and waste barrier contamination. PMID:23188711

  20. Natural Iraqi palygorskite clay as low cost adsorbent for the treatment of dye containing industrial wastewater.

    PubMed

    Nassir Taha, Dakhil; Sadi Samaka, Isra'a

    2012-01-01

    In this study, natural Iraqi low- cost locally available clay (palygorskite) was studied for its potential use as an adsorbent for removal Congo red from aqueous solutions. Batch type experiments were conducted to study the effect of contact time, initial pH of the dye solution, initial dye concentration, adsorbent dosage, and particle size of adsorbent on adsorption capacity of Congo red. The adsorption occurred very fast initially and attains equilibrium within 60 min. When the effect of pH of solution dye on the yield adsorption has been carried in a range of 2-10, the adsorption obtained was nearly the same with very slightly effect of pH and it was reported that above 49.07 mg/g of Cong red by palygorskite clay occurred in the pH range 2 to 10. It was observed that the removal of Congo red increase with increasing initial dye concentration and adsorbent dose, but, adsorption capacity decrease with increasing adsorbent dose. The adsorption capacity increase with decreasing particle size of adsorbent. The equilibrium adsorption data were interpreted using Langmuir and Freundlich isotherm models. The obtained results revealed that the equilibrium data closely followed both models, but the Langmuir isotherm fitted the data better. The maximum adsorption capacity was found to be 99 mg/g at ambient temperature. Results indicate that Iraqi palygorskite clay could be employed as a low cost alternative to commercial activated carbon in wastewater treatment for the removal of colour and dyes. PMID:23196874