The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Fereshteh Mirahmadi - One of the best experts on this subject based on the ideXlab platform.
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diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar induced collagen crosslinking
Journal of The Mechanical Behavior of Biomedical Materials, 2019Co-Authors: Fereshteh Mirahmadi, J H Koolstra, S Fazaeli, Frank Lobbezoo, Harry G Van Lenthe, Jessica Snabel, Reinout Stoop, Vincent EvertsAbstract:Nutrition of articular cartilage relies mainly on diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their diffusion. Normalized Concentration of contrast agents in the cartilage and contrast agent diffusion flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the Normalized Concentration and diffusion flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the diffusion properties.Nutrition of articular cartilage relies mainly on diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their diffusion. Normalized Concentration of contrast agents in the cartilage and contrast agent diffusion flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the Normalized Concentration and diffusion flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the diffusion properties.
Vincent Everts - One of the best experts on this subject based on the ideXlab platform.
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diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar induced collagen crosslinking
Journal of The Mechanical Behavior of Biomedical Materials, 2019Co-Authors: Fereshteh Mirahmadi, J H Koolstra, S Fazaeli, Frank Lobbezoo, Harry G Van Lenthe, Jessica Snabel, Reinout Stoop, Vincent EvertsAbstract:Nutrition of articular cartilage relies mainly on diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their diffusion. Normalized Concentration of contrast agents in the cartilage and contrast agent diffusion flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the Normalized Concentration and diffusion flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the diffusion properties.Nutrition of articular cartilage relies mainly on diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their diffusion. Normalized Concentration of contrast agents in the cartilage and contrast agent diffusion flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the Normalized Concentration and diffusion flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the diffusion properties.
Frederic Pignon - One of the best experts on this subject based on the ideXlab platform.
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layered organization of anisometric cellulose nanocrystals and beidellite clay particles accumulated near the membrane surface during cross flow ultrafiltration in situ saxs and ex situ sem waxd characterization
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020Co-Authors: Enrico Federico Semeraro, Nicolas Hengl, Mohamed Karrouch, Laurent J Michot, Erwan Paineau, Bruno Jean, Jeanluc Putaux, Christine Lancelonpin, Lewis Sharpnack, Frederic PignonAbstract:Abstract The structural organization of the Concentration polarization layer (CPL) during the cross-flow membrane separation process of anisometric aqueous suspensions of colloidal cellulose nanocrystals and beidellite clay particles has been characterized by in situ time-resolved small-angle X-ray scattering (SAXS). Dedicated cross-flow filtration cells were implemented on the ID02 TRUSAXS beamline at the European Synchrotron Radiation Facility (Grenoble, France). From the analysis of the scattered intensities and structure factors of particles in the CPL, both the Concentration profiles ɸ(Δz,Δt) and anisotropic structural organization have been characterized as a function of filtration time (Δt) and distance from the membrane surface (Δz). Remarkably, a coupling between Concentration and anisotropy was revealed and modeled using either a simple or stretched exponential trend for rod- or disk-like systems, respectively. Using a simple filtration model, the time evolution of the deposit thickness, membrane resistance and specific resistance of the deposit, deduced from an analysis of the Normalized Concentration profiles, allowed directly predicting the rapid decay of permeate flux associated to the exponential growth of Concentration and anisotropic organization inside the CPL. Ex situ scanning electron microscopy (SEM) observations and wide-angle X-ray diffraction (WAXD) analyses performed on dried deposits parallel and perpendicular to the membrane surface revealed well-defined layered structures from nanometer to micrometer length scales.
Christopher P Niewoehner - One of the best experts on this subject based on the ideXlab platform.
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soil and hydrologic effects on fate and horizontal transport in the capillary fringe of surface applied nitrate
Geoderma, 2012Co-Authors: Sergio M Abit, Aziz Amoozegar, Michael J Vepraskas, Christopher P NiewoehnerAbstract:Substantial horizontal solute transport has been demonstrated to occur in the capillary fringe (CF) above a flowing ground water, yet the importance of the CF for solute movement has generally been ignored. This study was conducted to evaluate the fate and horizontal transport of surface-applied nitrate (NO3−) in the CF under simulated hydrologic conditions that varied flow rates. Two soils of different organic carbon content were packed in separate 240-cm long, 60-cm high and 25-cm thick flow cells. A simulated water table (WT) was established at 20 cm above the bottom of each flow cell and different pore-water velocities across the flow cell were simulated while a solution containing NO3− and bromide (Br−) was continuously applied over a small area on the surface of the soil in the flow cell. Soil solution samples were collected from two depths below the WT and two depths within the CF above the WT at four locations along the flow cell. Subsurface horizontal transport of surface-applied NO3− tended to occur exclusively in the CF as the pore-water velocity was increased. In the flow cell with soil having a small amount of organic carbon (0.3 g kg− 1), Normalized Concentration of NO3− and Br− remained very comparable at all monitoring locations above and below the WT. Nitrate loss via denitrification in this case was not observed as conditions were oxidizing. In flow cells with soils having an organic carbon content of 35 g kg− 1, some Br− was detected below the WT while NO3− was essentially absent. Conditions below the WT favored NO3− loss via denitrification as reflected by very low redox potentials (< 250 mV). These results suggest that collection of samples from the CF should be considered when monitoring subsurface fate and transport of surface-applied NO3− in locations with laterally moving shallow ground water.
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fate of nitrate in the capillary fringe and shallow groundwater in a drained sandy soil
Geoderma, 2008Co-Authors: Sergio M Abit, Aziz Amoozegar, Michael J Vepraskas, Christopher P NiewoehnerAbstract:Abstract It is commonly assumed that nitrate (NO 3 − ) and other anions entering the soil move downward through the vadose zone, and then move horizontally in the groundwater. Recent laboratory studies, however, indicate that water movement and transport of pollutants can also take place in the capillary fringe (CF) above the water table (WT). This field study evaluated the fate of NO 3 − in the CF and shallow groundwater (SGW) for a sandy soil (Aeric Alaquod) with shallow water table. Ten L of a solution containing approximately 18 mmol L − 1 nitrate [2.66 g L − 1 Mg(NO 3 ) 2 ] and 77 mmol L − 1 bromide (9.12 g L − 1 KBr) were applied to the soil above the CF. The movement of both NO 3 − and Br − was monitored for 84 days by using tension lysimeters installed at depths between 45 and 105 cm at radial distances of 20, 60, 120, 220 and 320 cm from the application point. Nitrate and Br − plumes that entered the CF from the unsaturated zone moved horizontally in the CF until both species were partially carried into the groundwater by the fluctuating WT following rain events. Normalized Concentrations of NO 3 − N and Br − remained comparable as they moved horizontally in the CF up to 320 cm from the tracer application spot. However, below the WT the detected Normalized Concentration of Br − was higher than that for NO 3 − indicating nitrate loss, perhaps due to denitrification. When monitoring subsurface NO 3 − , solely relying on collection of groundwater samples may lead to an underestimation of the extent of NO 3 − contamination and transport in the subsurface.
Timothy E Long - One of the best experts on this subject based on the ideXlab platform.
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synthesis and solution rheology of adenine containing polyelectrolytes for electrospinning
Polymer, 2012Co-Authors: Sean T Hemp, Matthew T Hunley, Shijing Cheng, Kerry C Demella, Timothy E LongAbstract:Abstract Conventional free radical copolymerization of 9-vinylbenzyladenine (VBA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) with subsequent protonation afforded the synthesis of adenine-containing polyelectrolytes. All adenine-containing polyelectrolytes exhibited classical polyelectrolyte solution rheological behavior with scaling factors near 0.6 and 1.6 in the semidilute unentangled and semidilute entangled regimes, respectively. However, the adenine-containing polyelectrolytes deviated from polyelectrolyte behavior in the concentrated regime with increasing scaling factors as adenine-incorporation increased due to intermolecular association. The electrospinning behavior exhibited a strong dependence on adenine incorporation. Higher adenine-incorporation decreased the Normalized Concentration for fiber formation from 4.5C e for PDMAEMA•HCl to 2.9C e for 35 mol% VBA. The required zero-shear viscosities for electrospinning were 312 cP for PDMAEMA•HCl and 116 cP for the 35 mol% VBA copolymer. Increasing the adenine Concentration also increased the fiber diameters presumably due to adenine–adenine interactions. These adenine-decorated electrospun mats exhibit potential in a variety of applications including filtration, purification, and tissue scaffolding.
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correlations of solution rheology with electrospun fiber formation of linear and branched polyesters
Macromolecules, 2004Co-Authors: Matthew G Mckee, Garth L Wilkes, Ralph H Colby, Timothy E LongAbstract:The implications of the entanglement Concentration (Ce) on the electrospinning process for a series of linear and branched poly(ethylene terephthalate-co-ethylene isophthalate) (PET-co-PEI) copolymers with weight-average molecular weights (Mw) ranging from 11 700 to 106 000 g/mol and branching index values (g‘) from 1.0 to 0.43 were investigated. Analyzing the dependence of specific viscosity (ηsp) on Concentration enabled the determination of the semidilute unentangled, semidilute entangled, and concentrated regimes for the PET-co-PEI solutions. Linear and branched copolymers were electrospun from semidilute unentangled, semidilute entangled, and concentrated solutions under identical conditions to determine the effects of Concentration regime and molecular topology on electrospun fiber morphology. The dependence of the fiber diameter and morphology on the zero shear rate viscosity (η0) and Normalized Concentration (C/Ce) was determined. For copolyesters with molecular weights well above the entanglement...
