High Performance Ultrasonic Inspection of Tubes

Eddy current examination was selected as the industrial method to be used for the inspection of PWR steam generator tubes because of both physical and operational advantages

Impact of pNIPAM Microgel Size on Its Ability To Stabilize Pickering Emulsions

We study the influence of the particle size on the ability of poly(N-isoprolylacrylamide) microgels to stabilize direct oil-in-water Pickering emulsions. The microgel size is varied from 250 to 760 nm, the cross-linking density being kept constant. The emulsion properties strongly depend on the stabilizer size: increasing the particle size induces an evolution from dispersed drops and fluid emulsions toward strongly adhesive drops and flocculated emulsions. In order to get insight into this dependency, we study how particles adsorb at the interface and we determine the extent of their deformation. We propose a correlation between microgel ability to deform and emulsion macroscopic behavior. Indeed, as the microgels size increases, their internal structure becomes more heterogeneous and so does the polymeric interfacial layer they form. The loss of a uniform dense layer favors bridging between neighboring drops, leading to flocculated and therefore less handleable emulsions

Pickering emulsion as template for porous bioceramics in the perspective of bone regeneration

International audienceCalcium phosphate (CaP) based bioceramics are widely used as bone substitutes. The most encountered CaP ceramics are obtained from high temperature phases. However, their bioactivity and their association with biomolecules are limited, as well as their bioresorption in-vivo. The aim of this work is to develop biomimetic low temperature apatites ceramics with tunable porosity via biocompatible high internal phase Pickering emulsions. The biocompatible emulsions developed were stabilized by stoichiometric hydroxyapatite (HA) particles. Several parameters (mass of HA particles, oil/water weight ratio, electrolytes concentration in the aqueous phase) were investigated to define the optimized formulation conditions leading to a kinetically stable monodisperse emulsion with a minimum drop diameter of 200 µm and drops enough percolated to induce interconnected porosity. Two types of porous bioceramics were produced by low temperature processes with controlled composition and porosity, evidenced by X-ray microtomography: calcium phosphate monoliths from an apatitic gel, and silica-HA monoliths via a sol-gel process. These low temperature processes should provide bioceramics able to perform bioactivity and bio-resorption in-vivo, and could prefigure a drug or other therapeutic ions-delivery disposals for filling bone defects in maxillofacial or orthopedic surgery

Fundamental study of emulsions stabilized by soft and rigid particles

Two distinct uniform hybrid particles, with similar hydrodynamic diams. and comparable zeta potentials, were prepd. by copolymg. N-iso-Pr acrylamide (NIPAM) and styrene. These particles differed in their styrene to NIPAM (S/N) ratios of 1 and 8, and were referred to as S/N 1 and S/N 8. Particle S/N 1 exhibited typical behavior of soft particles, i.e., the particles shrank in bulk aq. solns. when the temp. was increased. As a result, S/N 1 particles were interfacially active. In contrast, particle S/N 8 appeared to be rigid in response to temp. changes. In this case, the particles showed negligible interfacial activity. Interfacial shear rheol. tests revealed the increased rigidity of the particle-stabilized film formed at the heptane-water interface by S/N 1 than S/N 8 particles. As a result, S/N 1 particles were shown to be better emulsion stabilizers and emulsify a larger amt. of heptane compared to S/N 8 particles. The current investigation confirmed a better performance of emulsion stabilization by soft particles (S/N 1) than by rigid particles (S/N 8), reinforcing the importance of controlling softness or deformability of particles for the purpose of stabilizing emulsions. [on SciFinder(R)