The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
James E. Blair - One of the best experts on this subject based on the ideXlab platform.
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Sedimentation velocity determinations of molecular weight distributions
Journal of Polymer Science Part C: Polymer Symposia, 2007Co-Authors: James E. BlairAbstract:In the sedimentation velocity experiment, the ultracentrifuge fractionates the molecules according to molecular weight, along the radial axis in the rotating cell. The boundary Gradient Curve measured during the experiment can be transformed into an apparent distribution of sedimentation coefficients, which can twined to determine the true sediment at ion coefficient distribution by the introduction of a number of corrections. This true distribution can often be converted into the weight distribution of molecular weights. This paper discusses the current views of each of these corrections, which account for the effects of diffusion, hydrostatic pressure, concentration, and the time needed to attain operating speed. The sensitivity of the resultant molecular weight distribution to several parameters is indicated for a polystyrene sample.
Masashi Nojima - One of the best experts on this subject based on the ideXlab platform.
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Shave-Off Profiling for TEM Specimens
The Transmission Electron Microscope - Theory and Applications, 2015Co-Authors: Masashi NojimaAbstract:This work aims to compare the results from the same specimens between shave-off profiling and TEM image. For the cross-check analysis, a specimen was picked up from a part was failed integrated chip (IC) package that may have suffered electro‐ chemical migration. Critical disagreement between the results was found in the Gradient Curve of the shave-off profiling from the anode to the cathode. In each package, shave-off profiling revealed a faint Gradient Curve on migrated ions that could not be revealed from TEM image.
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Shave-off vector profiling for TEM samples
Applied Surface Science, 2008Co-Authors: Masashi Nojima, M. Fujii, Y. Ishizaki, Masanori Owari, Yoshimasa NiheiAbstract:Abstract This study aims to cross-check the same sample, the same part and the same piece by shave-off profiling and scanning transmission electron microscope (STEM) imaging. For cross-check analysis, a piece was picked up from a failed IC package which might cause electrochemical migration. Critical disagreement on each result was Gradient Curve on shave-off depth profiling from anode to cathode. In the same piece, shave-off profiling visualized a faint Gradient of migrated ions which could not be observed by STEM imaging.
Yoshimasa Nihei - One of the best experts on this subject based on the ideXlab platform.
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Shave-off vector profiling for TEM samples
Applied Surface Science, 2008Co-Authors: Masashi Nojima, M. Fujii, Y. Ishizaki, Masanori Owari, Yoshimasa NiheiAbstract:Abstract This study aims to cross-check the same sample, the same part and the same piece by shave-off profiling and scanning transmission electron microscope (STEM) imaging. For cross-check analysis, a piece was picked up from a failed IC package which might cause electrochemical migration. Critical disagreement on each result was Gradient Curve on shave-off depth profiling from anode to cathode. In the same piece, shave-off profiling visualized a faint Gradient of migrated ions which could not be observed by STEM imaging.
David A Sabatini - One of the best experts on this subject based on the ideXlab platform.
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Improving the extraction of tetrachloroethylene from soil columns using surfactant Gradient systems.
Journal of contaminant hydrology, 2004Co-Authors: Jeffrey D Childs, Edgar Acosta, Robert Knox, Jeffrey H Harwell, David A SabatiniAbstract:In this work, we extend the recently developed Gradient approach for surfactant-enhanced remediation of dense non-aqueous phase liquid (DNAPL)-impacted sites. The goal of the Gradient approach is to maximize the DNAPL solubilization capacity in swollen micelles (Type I aqueous microemulsions) while at the same time minimizing the potential for DNAPL mobilization. In this work, we introduce a modified version of the capillary/trapping Curve that we refer to as the Gradient Curve to help interpret and/or design the Gradient approach. The Gradient Curve presents the residual DNAPL saturation as a function of interfacial tension and microemulsion viscosity. This approach demonstrates that keeping a low viscosity of the microemulsion phase is not only important for keeping a low head loss during surfactant flooding but also to prevent oil mobilization. Eight microemulsion systems were evaluated in this research; these systems were evaluated based on their tetrachloroethylene (PCE) solubilization capacity, interfacial tension (IFT), viscosity, density, and coalescence kinetics. Two of these systems were chosen for evaluation in site-specific column tests using an increasing electrolyte Gradient to produce a decreasing IFT/increasing solubilization Gradient system. The column studies were conducted with media from Dover Air Force Base in Dover, DE. Both solubilized and mobilized DNAPL were quantified. During the column studies, we observed that substantial PCE was mobilized when the residual level of PCE in the column was significantly higher than the steady-state residual saturation level being approach (as predicted from the Gradient Curve). Four column studies were performed, three of which were used to asses the validity of the Gradient Curve in predicting the residual saturation after each Gradient step. From these tests we observed that starting IFTs of less than 1 mN/m all produced the same mobilization potential. In the last column, we used an additional Gradient step with an initial IFT above 1 mN/m to dramatically reduce the amount of PCE mobilize. Based on the good agreement between column results and projections based on the Gradient Curve, we propose this as a preferred method for designing Gradient surfactant flushing systems.
Francoise Sage - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamic processes velocity structure and stratification in natural turbidity currents results inferred from field data in the var turbidite system
Sedimentary Geology, 2012Co-Authors: Sébastien Migeon, Bruno Savoye, Thierry Mulder, Francoise SageAbstract:Abstract The Var Turbidite System (NW Mediterranean Sea) is fed during the present-day highstand sea level by large earthquake-induced ignitive turbidity currents, low-density turbidity currents resulting from retrogressive failures triggered on the upper continental slope, and hyperpycnal flows related to the Var River floods. Using a large dataset including bathymetric data, side-scan sonar images, seismic-reflection profiles, cores and photographs of the seafloor, this paper attempts to better constrain the hydrodynamic behaviour of debris flows and turbidity currents along the Upper and Middle Valley of the Var Turbidite System. The drastic change of the seafloor morphology between the Upper and the Middle Valley suggests that gravity flows undergo rapid transformation from cohesive to fully turbulent behaviour. This transformation is related to a hydraulic jump caused by an abrupt decrease in slope angle at the transition between the Upper and the Middle Valley and is associated with en masse deposition and elevation of the seafloor. Strong seafloor erosion prevails in the Middle Valley, suggesting that, for a low and constant slope angle, turbulent flows must regain a balance between concentration and flow thickness rapidly after they experience hydraulic jump. The internal stratification and vertical grain-size distribution within turbulent flows are inferred from the distribution of fine- to coarse-grained turbidites found in cores located along the crest of the Var Sedimentary Ridge with a decreasing elevation above the floor of the Middle Valley. The theoretical vertical velocity profile deduced from the vertical grain-size distribution exhibits a general trend and an inflection of the Gradient Curve different from those of the velocity profiles classically obtained using numerical modelling.
