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Martinus Th Van Genuchten - One of the best experts on this subject based on the ideXlab platform.
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determination of specific lnapl volumes in soils having a multimodal Pore Size distribution
Journal of Environmental Management, 2019Co-Authors: Miguel Angel Alfaro Soto, R J Lenhard, Hung K Chang, Martinus Th Van GenuchtenAbstract:Abstract In this paper we present modifications to previously published models for determining the specific volume of non-aqueous phase liquids (LNAPLs) in the subsurface at and near the groundwater table following a spill or leak from the soil surface. The modifications account for porous media having multimodal Pore-Size distributions as is often the case with tropical soils. Data from the literature are used to show that the use of multimodal Pore-Size distributions can lead to significantly different subsurface LNAPL specific volume predictions and possible LNAPL recovery rates, compared to when only unimodal Pore-Size distributions are considered. Differences of up to 200% are possible when the dual-porosity nature of the Pore system is ignored, which can yield erroneous estimates of the time needed to remediate LNAPLs from contaminated areas when conventional systems are employed.
Yury Gogotsi - One of the best experts on this subject based on the ideXlab platform.
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Effect of Pore Size and its dispersity on the energy storage in nanoporous supercapacitors
Energy & Environmental Science, 2012Co-Authors: Svyatoslav Kondrat, Carlos R. Perez, Volker Presser, Yury Gogotsi, Alexei A. KornyshevAbstract:This paper focuses on the choice of the optimal Pore Size and the effect of Pore Size dispersion, which is important for the rational design of nanoporous supercapacitors. Optimization of the Pore Size of nanoporous carbon electrodes is discussed in terms of the maximal stored energy density. By applying a previously developed theory, and supporting it by newly performed experiments, we find that the energy density is a non-monotonic function of the Pore Size of monodisperse porous electrodes. The ‘optimal’ Pore Size that provides the maximal energy density increases with increasing operating voltage and saturates at high voltages. We also analyse how the Pore Size distribution affects the voltage dependent capacitance and the stored energy density, and show that the latter is maximized for monodisperse electrodes.
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importance of Pore Size in high pressure hydrogen storage by porous carbons
International Journal of Hydrogen Energy, 2009Co-Authors: Yury Gogotsi, Cristelle Portet, Sebastian Osswald, Jason M Simmons, Taner Yildirim, Giovanna Laudisio, John E FischerAbstract:Abstract Development of high-capacity hydrogen-storage systems utilizing physisorption at high pressure and low temperature is hindered by poor understanding of the Pore Size/shape requirements for achieving the maximum hydrogen uptake. Tuning the carbon structure and Pore Size of carbide-derived carbons (CDCs) with high accuracy by using different starting carbides, chlorination temperatures and activation temperatures allows rational design of carbon materials with increased hydrogen-storage capacity. Systematic experimental investigation of a large number of CDCs with controlled Pore Size distributions and specific surface area (SSA) shows that Pores larger than ∼1.5 nm contribute little to hydrogen storage. It has been experimentally demonstrated that, just as at ambient pressure, Pores of 0.6–0.7 nm in diameter provide the largest H 2 uptake per unit SSA at elevated pressures and liquid nitrogen temperatures. The effect of Pore Size was stronger than the effect of surface chemistry on the hydrogen uptake.
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effect of Pore Size and surface area of carbide derived carbons on specific capacitance
Journal of Power Sources, 2006Co-Authors: John Chmiola, Gleb Yushin, Ranjan Dash, Yury GogotsiAbstract:Abstract This work presents a systematic study on how Pore Size and specific surface area (SSA) of carbon effect specific capacitance and frequency response behavior. Carbide derived carbons (CDC) produced by leaching metals from TiC and ZrC at temperatures from 600 to 1200 °C have highly tailorable microstructure and porosity, allowing them to serve as excellent model systems for porous carbons in general. BET SSA and average Pore Size increased with synthesis temperature and was 600–2000 m 2 g −1 and 0.7–1.85 nm, respectively. Maximum specific capacitance in 1 M H 2 SO 4 was found to occur at an intermediate synthesis temperature, 800 °C, for both ZrC and TiC derived carbons and was 190 and 150 F g −1 , respectively. Volumetric capacitance for TiC and ZrC derived carbons was maximum at 140 and 110 F cm −3 . These results contradict an oft-reported axiom that increasing Pore Size and SSA, all other things being held constant, increases specific capacitance. A correlation between specific capacitance and SSA of microPores (less than 2 nm in diameter) has been shown. As expected, increasing Pore Size was found to improve the frequency response. However, CDCs with similar Pore Size distributions but obtained from different starting materials showed noticeable differences in impedance behavior. This highlights the importance of not only the Pore Size and specific surface area measured using gas sorption techniques, but also the Pore shape or tortuousity, which is non-trivial to characterize, on energy storage.
Il Kyu Park - One of the best experts on this subject based on the ideXlab platform.
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in vitro and in vivo characteristics of pcl scaffolds with Pore Size gradient fabricated by a centrifugation method
Biomaterials, 2007Co-Authors: Se Heang Oh, Il Kyu ParkAbstract:Abstract Polycaprolactone (PCL) cylindrical scaffolds with gradually increasing Pore Size along the longitudinal direction were fabricated by a novel centrifugation method to investigate Pore Size effect on cell and tissue interactions. The scaffold was fabricated by the centrifugation of a cylindrical mold containing fibril-like PCL and the following fibril bonding by heat treatment. The scaffold showed gradually increasing Pore Size (from ∼88 to ∼405 μm) and porosity (from ∼80% to ∼94%) along the cylindrical axis by applying the centrifugal speed, 3000 rpm. The scaffold sections were examined for their in vitro cell interactions using different kinds of cells (chondrocytes, osteoblasts, and fibroblasts) and in vivo tissue interactions using a rabbit model (skull bone defects) in terms of scaffold Pore Sizes. It was observed that different kinds of cells and bone tissue were shown to have different Pore Size ranges in the scaffold for effective cell growth and tissue regeneration. The scaffold section with 380–405 μm Pore Size showed better cell growth for chondrocytes and osteoblasts, while the scaffold section with 186–200 μm Pore Size was better for fibroblasts growth. Also the scaffold section with 290–310 μm Pore Size showed faster new bone formation than those of other Pore Sizes. The Pore Size gradient scaffolds fabricated by the centrifugation method can be a good tool for the systematic studies of the interactions between cells or tissues and scaffolds with different Pore Size.
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in vitro and in vivo characteristics of pcl scaffolds with Pore Size gradient fabricated by a centrifugation method
Biomaterials, 2007Co-Authors: Il Kyu Park, Jin Man Kim, Jin Ho LeeAbstract:Polycaprolactone (PCL) cylindrical scaffolds with gradually increasing Pore Size along the longitudinal direction were fabricated by a novel centrifugation method to investigate Pore Size effect on cell and tissue interactions. The scaffold was fabricated by the centrifugation of a cylindrical mold containing fibril-like PCL and the following fibril bonding by heat treatment. The scaffold showed gradually increasing Pore Size (from approximately 88 to approximately 405 microm) and porosity (from approximately 80% to approximately 94%) along the cylindrical axis by applying the centrifugal speed, 3000 rpm. The scaffold sections were examined for their in vitro cell interactions using different kinds of cells (chondrocytes, osteoblasts, and fibroblasts) and in vivo tissue interactions using a rabbit model (skull bone defects) in terms of scaffold Pore Sizes. It was observed that different kinds of cells and bone tissue were shown to have different Pore Size ranges in the scaffold for effective cell growth and tissue regeneration. The scaffold section with 380-405 microm Pore Size showed better cell growth for chondrocytes and osteoblasts, while the scaffold section with 186-200 microm Pore Size was better for fibroblasts growth. Also the scaffold section with 290-310 microm Pore Size showed faster new bone formation than those of other Pore Sizes. The Pore Size gradient scaffolds fabricated by the centrifugation method can be a good tool for the systematic studies of the interactions between cells or tissues and scaffolds with different Pore Size.
Kaoru Fujimoto - One of the best experts on this subject based on the ideXlab platform.
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supercritical phase fischer tropsch synthesis catalyst Pore Size effect
Aiche Journal, 1992Co-Authors: Li Fan, Kohshiroh Yokota, Kaoru FujimotoAbstract:The Fischer-Tropsch synthesis reaction was conducted in a supercritical fluid medium using a fixed-bed reactor. Tailor-made catalyst supports which had sharp Pore diameter distributions were prepared by the pH swing method. The relationships between the catalyst Pore structure and the catalytic activity or the product distribution were studied. The influence of the catalyst Pore Size on the mass transfer of reactants and products was also characterized. The catalyst Pore Size affected not only catalytic activity but also product selectivity. The diffusion of reactants inside the catalyst pellets in the supercritical fluid media was simulated and the effects of catalyst Pore Size and catalyst particle Size on catalytic performances were consistent with simulation results.
Dechen Song - One of the best experts on this subject based on the ideXlab platform.
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effect of catalyst Pore Size on the catalytic performance of silica supported cobalt fischer tropsch catalysts
Journal of Molecular Catalysis A-chemical, 2006Co-Authors: Dechen SongAbstract:Abstract A series of cobalt catalysts supported on silica with different Pore Size were prepared by incipient wetness impregnation method. N 2 physisorption, XRD, H 2 -TPR, H 2 -TPD, DRIFTS and O 2 pulse reoxidation were used to characterize the catalysts. The results showed that the Pore Size of the support had a significant influence on the Co 3 O 4 crystallite diameter, catalyst reducibility and Fischer–Tropsch activity. The larger Pore could cause the Co/SiO 2 to form larger Co 3 O 4 crystallite and decreased its dispersion. Catalysts with different Pore Size showed different CO adsorption property. The catalysts with Pore Size of 6–10 nm displayed higher Fischer–Tropsch activity and higher C 5+ selectivity, due to the moderate particle Size and moderate CO adsorption on the catalysts.
