Analytical Solutions to the Problem of the Grain Groove Profile

During the last sixty years, the problem of the formation of grain boundary grooving in polycrystalline thin films, was largely studied, analyzed and commented. The thermal effect on the properties of the grain boundary grooving was first studied by Mullins in his famous paper published in 1957 and then by other authors. This paper constitutes a new contribution on the correction of Mullins problem in the case of the evaporation-condensation and proposes a more accurate solution of the partial differential equation governing the geometric profile of the grain boundary grooving. The Mullins hypothesis neglecting the first derivative (|y'|< < 1) in the main equation was defeated by our new solution. In this paper, we proved that the new proposed mathematical solution giving the solution y(x, t) is valid for all x values without any approximation on the first derivative y'

New solution of the partial differential equation of the grain groove profile problem in the case of evaporation/condensation

This paper constitutes a new contribution on the resolution of Mullins problem in the case of the evaporation-condensation and gives an exact and explicit solution of the second partial differential equation relative to the geometric profile of the grain boundary grooving

Thermal Fatigue Effect on the Grain Groove Profile in the Case of Diffusion in Thin Polycrystalline Films of Power Electronic Devices

In a previous paper, we solved the partial differential equation of Mullins’ problem in the case of the evaporation–condensation in electronic devices and gave an exact solution relative to the geometric profile of the grain boundary grooving when materials are submitted to thermal and mechanical solicitation and fatigue effect. In this new research, new modelling of the grain groove profile was proposed and new analytical expressions of the groove profile, the derivative and the groove depth were obtained in the case of diffusion in thin polycrystalline films by the resolution of the fourth differential equation formulated by Mullins that supposed y′2≪1. The obtained analytical solution gave more accurate information on the geometric characteristics of the groove that were necessary to study the depth and the width of the groove. These new findings will open a new way to study with more accuracy the problem of the evaporation–condensation combined to the diffusion phenomenon on the material surfaces with the help of the analytical solutions

Instrumentation of hollow fiber flow field flow fractionation for selective cell elution

International audienceHollow fiber flow field flow fractionation (HF5) columns can be built with minimized cost and instrumental skills by incorporation of commercial hollow fibers into holders made of classical chromatographic tubing and connectors. The proposed design leads to differential elution of human cells of different origin. Suspensions of red blood cells (RBC) and adherent human colorectal cancer (CRC) cell lines were used. These CRC nucleated population have been linked to cell-to-cell and cell to instrument interactions that are limiting factors in terms of recovery and viability. These interactions can be limited depending on injection/elution conditions. By using RBC we observed that the focalization/relaxation step played a major role in the elution process. However, HF5 opens a large potential, which completes the diversity shown by SdFFF in cell sorting methodologies and technologies

Instrumentation of hollow fiber flow field flow fractionation for selective cell elution.

International audienceHollow fiber flow field flow fractionation (HF5) columns can be built with minimized cost and instrumental skills by incorporation of commercial hollow fibers into holders made of classical chromatographic tubing and connectors. The proposed design leads to differential elution of human cells of different origin. Suspensions of red blood cells (RBC) and adherent human colorectal cancer (CRC) cell lines were used. These CRC nucleated population have been linked to cell-to-cell and cell to instrument interactions that are limiting factors in terms of recovery and viability. These interactions can be limited depending on injection/elution conditions. By using RBC we observed that the focalization/relaxation step played a major role in the elution process. However, HF5 opens a large potential, which completes the diversity shown by SdFFF in cell sorting methodologies and technologies

Flow and stop flow elution of proteins in hollow fiber flow field flow fractionation (HF5) systems

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Physicochemical-microstructural approach for modeling the crack passage at topside metallic parts in IGBT semiconductor power electronics

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Dye-free determination of the focalization position for the hollow fiber flow field flow fractionation (HF5) of proteins

International audienceProteins are separated in field flow fractionation (FFF) according to a well-established mechanism described as the “Normal or Brownian” mode. In the case of the sub-technique using a hollow fiber, the focalization/relaxation position can be observed visually only with a transparent holder and using dyes as samples. Whatever the choice of instrumentation, a dye-free method is proposed to determine the center of the zone from experimental fractograms by means of only two sample elutions. It is also possible to determine and model the kinematics of the sample toward the equilibrium focalization/relaxation position as well as the real dimensions of the fiber during the separation process

Naphthyl-Naphthalimides as High-Performance Visible Light Photoinitiators for 3D Printing and Photocomposites Synthesis

International audienceIn this article, five new organic dyes based on the naphthalimide scaffold (Napht-1-Napht-5) were synthesized and tested as high-performance photoinitiators for both the Free Radical Photopolymerization (FRP) of acrylates and the Cationic Polymerization (CP) of epoxides using blue Light-Emitting Diodes (LEDs) as a safe irradiation source (LED @405 nm and 455). In fact, very good photopolymerization profiles (high final conversions and high polymerization rates) were obtained once these photoinitiators were combined with an Iodonium salt (Iod) or Iod/amine NPG and NVK). Remarkably, these dyes were able to generate interpenetrating polymer networks (IPN) by polymerization of a blend of monomers. These experiments were carried out to improve the polymerization profiles as well as the mechanical properties of the obtained materials. Due to their high photoinitiation abilities, these compounds were used in some applications such as photocomposite synthesis, direct laser write, and 3D printing experiments. To determine the chemical mechanisms, the photochemical/photophysical properties of these compounds were studied using different characterization techniques such as U

Europium labeled lactosylated albumin as a model workflow for the development of biotherapeutics

International audienceLactosylated albumin is currently used as a radiopharmaceutical agent to image the liver asialoglycoprotein receptors and quantify hepatic liver function in various diseases. A lactosylated protein (LACTAL) conjugate showed excellent liver uptake compared to non-lactosylated protein and a high signal to noise ratio, based on the biodistribution in mice using 99mTc-scintigraphy. However, in the laboratory, it is useful to have a method that can be used in daily practice to quantify cellular targeting or biodistribution. We propose a methodology from synthesis validation to pre-clinical demonstration and introduce a new practical detector (LACTAL.Eu) of the LACTAL molecule in biological media. We confirmed the purity and colloidal stability of the sample through physical analytical techniques, then showed the absence of in vitro toxicity of the agent and demonstrated in vitro targeting. Taking advantage of the fluorescence decay of the lanthanide, we performed measurements directly on the cell media without any further treatment. Finally, biodistribution in mice was confirmed by ex vivo measurements