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Showing 1 to 20 of 37 for “"macropore"”.
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Preferential movement of solutes through soils
… in heterogeneous soils with naturally occurring macropores were developed and evaluated. Field experiments, aimed at monitoring the occurrence of preferential flow and solute transport, were conducted in a conventionally-tilled and a no-till soybean field in the Coastal Plain of Virginia. A …
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AN INVESTIGATION OF SOIL WATER MOVEMENT ON DRAINED AND UNDRAINED CLAY GRASSLAND IN SOUTH WEST ENGLAND
… At the field and plot scale, the significance of macropore flow was noted. To investigate this in more detail, a tracer experiment was performed on an isolated soil block which had been mole drained and so had enhanced macroporosity. Macropore flow was generated under unsaturated conditions …
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Measurement and Simulation of Preferential Flow in Frozen Soils
… of cold regions. Preferential flow in macropores may enhance infiltration into frozen soil, but flow dynamics are complicated by coupled water and heat transfer processes. Field studies were conducted in the Canadian Prairies to evaluate the dominant mechanisms controlling preferential …
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Abundance, Distribution, and Geometry of Naturally Occurring Macropores in Stream Banks
… higher permeability than surrounding media. Macropores and soil pipes are a type of preferential flow path where conduit-like voids in the subsurface are typically greater than three millimeters in diameter. They are known to occur in agricultural and forest soils, often as a result of …
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Evaluation of flow models and pollutant retention isotherms for their application to rain garden bioretention
… affecting their retention were found to be macropore flow, pore water velocity, soil moisture content and soil characteristics and the primary method of modelling capture was identified as a sorption isotherm. Thus a dual-permeability heavy metal sorption model was developed; this was based …
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Comparative in vitro study of the proliferation and growth behavior of human osteoblast-like cells on various 2D-biomaterials
… biomaterials were synthetic biodegradable (MacroPore®, Ethisorb®, PDS®, Beriplast® P) and nonbiodegradable polymers (Palacos®) as well as calcium phosphate cement (BoneSource®) and titanium. Titanium and its alloys have been used worldwide in reconstructive surgery and dental implantation. …
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Preferential flow mechanisms : their interaction and effect on dye movement in till and glaciolacustrine sediment
… of the Northern Great Plains. Preferential flow (macropore, finger, and funnel) allows such chemicals to move relatively rapidly through materials considered to be aquitards. Preferential flow mechanisms at two sites in North Dakota, one in till, the other in glaciolacustrine sediments were …
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Macro- and micro-structural features direct bone regeneration in patterned biphasic calcium phosphate scaffolds
… calcium phosphate (BCP) scaffolds with both macropores and micropores (MP) show enhanced bone healing compared to those with macropores and no micropores (NMP), but the role of micropores is unclear. In this work, we assess the influence of scaffold macro- (> 300 μm) and microporosity (< 50 …
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Modeling transport of agricultural chemicals in a dual porosity system resulting from macropores
… transport in both the soil matrix and the macropore region. Flow of water in both regions is governed by Richards' equation and chemical transport is based upon convective-dispersive mechanisms with linear kinetic sorption and first-order decay. The pressure-water content and the …
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INVESTIGATIONS OF PREFERENTIAL AND MATRIX FLOW IN A MOLE DRAINED SOIL BLOCK
… a poorly structured relatively impermeable soil. Macropore channels were added by a mole plough in order to investigate soil water pathways and chemical transport in a soil in which preferential flow was guaranteed. The investigation focused on water and solute movement through specific flowpaths, …
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Integrated Numerical Modeling of Spatial and Time-Variant Hydrologic Response in Subsurface Drained Watersheds
… recessions. Drain flow simulations that included macropore flow resulted in higher magnitudes of response and better agreement with observed data, compared to simulations that considered sorptive flow alone. Simulations also showed that drain responses were in better agreement with observed flows …
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Impacts of biota on bioretention cell function during establishment in the Midwest
… in improving water quality, indicating that macropore flow in the earthworm treatments did not induce a higher rate of pollutant transport.
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The catalytic conversion of low chain length hydrocarbons to liquid fuels using ion exchange resin
… rate and selectively produces mainly dimers. Macropore diffusion resistance strongly influences the overall rate of the reaction. An increase in liquid production rate is obtained with increasing macroporosity, increasing degree of functionalization and decreasing catalyst bead size. A minimum …
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2-D and 3-D Temporal Modeling of Solute Migration through Low Permeable Media using Electrical Resistivity, Nacogdoches County, Texas
… of solute diffusion, but clearly identified macropore heterogeneity that increased advection transport; 3-D inversion modeling proved relatively ineffective. This study demonstrates the effectiveness of electrical resistivity characterization for delineating heterogenic and anisotropic …
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Recharge dynamics of a perched phreatic aquifer
… day as precipitation. They also showed that both macropore and matrix processes are at work in this system.
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Modification and Evaluation of a Water Balance Model to Simulate Corn Yields in Drained Waterways
… to include a variable hydraulic gradient and a macropore flow component.<br /> The water balance model was run for 17 years of climatic data (1986-1989, 1992-2000, and 2002-2005) collected at Brookings, South Dakota. The simulations were run for two conditions, one condition containing …
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Observation scale effects on fluid transport behavior of soil
… 60X100 mm; and 'large' cores were 100x150 mm. Macropore effects on solute transport were evaluated using monocontinuum and bicontinuum models. Bicontinuum-predicted solute breakthrough curves (BTC) closely agreed with observed BTC data with mean errors of reduced concentrations </- 0.05 for 97% …
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3D-printed adsorbents for gas separations: A material development, kinetic assessment, and process performance investigation
… loading method (Papers II-III, V-VI) and macropore space (Paper IV-VI) to determine how these properties relate to printed monoliths’ mass transfer rates. Objective three was addressed by varying the process conditions in a PSA system over a 3D-printed MOF-74 (Ni) monolith for …
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The Influence of Trees on Soil Hydraulic Properties : Species Effects and the Provision of Ecosystem Services.
… with significantly higher soil macroporosity and macropore flow. A mesocosm experiment, undertaken to investigate the influence of tree roots and associated soil macrofauna on Ks, was found to be of insufficient duration for significant changes to occur; however non-significant higher Ks observed …
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Adsorption of Pollutants on Charcoal Cloth in Simulated Guard Filters
… be represented by the Langmuir isotherm for the macropore region of the cloth. The micropore region is highly dependent on the manufacturing process due to variations in the quality of the cloth. This variation obstructs close correlation. The adsorbate-adsorbent mass ratio was obtained at …
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