1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

Vascular endothelial cells (ECs) are exposed to hemodynamic forces, which modulate EC functions and vascular biology/pathobiology in health and disease. The flow patterns and hemodynamic forces are not uniform in the vascular system. In straight parts of the arterial tree, blood flow is generally laminar and wall shear stress is high and directed; in branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress. Sustained laminar flow with high shear stress upregulates expressions of EC genes and proteins that are protective against atherosclerosis, whereas disturbed flow with associated reciprocating, low shear stress generally upregulates the EC genes and proteins that promote atherogenesis. These findings have led to the concept that the disturbed flow pattern in branch points and curvatures causes the preferential localization of atherosclerotic lesions. Disturbed flow also results in postsurgical neointimal hyperplasia and contributes to pathophysiology of clinical conditions such as in-stent restenosis, vein bypass graft failure, and transplant vasculopathy, as well as aortic valve calcification. In the venous system, disturbed flow resulting from reflux, outflow obstruction, and/or stasis leads to venous inflammation and thrombosis, and hence the development of chronic venous diseases. Understanding of the effects of disturbed flow on ECs can provide mechanistic insights into the role of complex flow patterns in pathogenesis of vascular diseases and can help to elucidate the phenotypic and functional differences between quiescent (nonatherogenic/nonthrombogenic) and activated (atherogenic/thrombogenic) ECs. This review summarizes the current knowledge on the role of disturbed flow in EC physiology and pathophysiology, as well as its clinical implications. Such information can contribute to our understanding of the etiology of lesion development in vascular niches with disturbed flow and help to generate new approaches for therapeutic interventions.

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Effects of Disturbed Flow on Vascular Endothelium: Pathophysiological Basis and Clinical Perspectives

Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems.

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Nonlinear dynamics and breakup of free-surface flows

Jets, ie collimated streams of matter, occur from the microscale up to the large-scale structure of the universe Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology They also arise from the last but one topology change of liquid masses bursting into sprays Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects

Physics of liquid jets

Discrete particle simulation of particulate systems: Theoretical developments

THIS CASE is presented to suggest a possible beneficial adjunct in the therapy of acute hemorrhagic pancreatitis. REPORT OF CASE J. S. (48600-51 Bellevue Hospital), a 25-year-old white woman, was admitted to the Fourth Surgical Division on July 31, 1951. For the past three years she had been troubled with recurrent attacks of right upper quadrant pain; the last attack occurred one month prior to admission, shortly before a Caesarean section was performed. Her postpartum course was uneventful. Five days before admission she noted the onset of a similar episode associated with nausea, vomiting, and pain radiating to her back. She was seen twice during this interval in the outpatient clinic, where she was given medication and sent home. On admission the patient appeared acutely ill. The temperature was 103.8 F. The blood pressure was 120/70, and the pulse was 128. She was perspiring profusely and appeared to be bordering

Acute hemorrhagic pancreatitis; report of a case with cortisone treatment.

Mixing of nano-particles by rapid expansion of high-pressure suspensions

Surface-treated hydrophobic aerogel (Nanogel) granules of sizes between 500 and 850 μm, 1.7 and 2.3 mm, and 0.5 and 2.3 mm are fluidized by a downward flow of oil-contaminated water in an inverse fluidization mode. Aerogel particles are nanostructured, extremely light and porous, have a very large surface area per unit mass, and are sufficiently robust to be fluidized. Their hydrophobic surface gives them a strong affinity for oil and other organic compounds, with the exclusion of water. These desirable properties make them an ideal sorbent or filter media for the removal of oil from wastewater. The hydrodynamic characteristics of inverse fluidized beds of aerogel granules of different size ranges were studied by measuring the pressure drop and bed expansion as a function of superficial velocity. The oil removal efficiency and capacity of the aerogel granules in the inverse fluidized bed were found to depend mainly on the size of the granules, the initial height of the bed (amount of powder used), the voi...

Removal of Oil from Water by Inverse Fluidization of Aerogels

Unsteady multiparticle creeping motions are complicated by the appearance of Basset, virtual mass and acceleration forces and by the difficulty of calculating fluid-particle interactions for three or more closely spaced particles. The present theoretical and experimental investigation explores the importance of each of these complicating features by examining in detail the gravitational-hydrodynamical interaction between three or more spheres falling along a common axis. The strong interaction theory developed to describe this motion accurately satisfies the viscous boundary conditions along the surface of each sphere and includes all the unsteady force terms in the equations of motion for the spheres. The experimental measurements for the three-sphere chain are in excellent agreement with theoretical predictions provided the Basset force is retained in the dynamic force balance. These results indicate, in general, that the Basset force is the most important unsteady force in gravitational flows at low Reynolds numbers in which the flow configuration is slowly changing due to fluid-particle interactions. The unsteady theory for small but finite Reynolds numbers shows that the departures in particle spacings, due to the integrated effect of the Basset force, from those predicted by quasi-steady zero Reynolds number theory grow as $ for large times and are of the order of the particle dimensions if the duration of the interaction is of 0(Re«1a/C/t). Here Rero is based on the terminal settling velocity U t and radius a of the sphere. This condition is satisfied in most sedimentation problems of interest. Virtual mass and particle acceleration forces on the other hand, are of negligible importance except during a short-lived initial transient period. An intriguing new feature of the three-sphere motion for large times was discovered. One finds that there is a critical initial spacing criterion which determines whether the two leading spheres in the chain will asymptotically approach a zero or a finite fluid gap as time goes to infinity. Numerical solutions for longer chains show that there is a tendency for the leading third of the chain to break up into doublets and triplets whereas the spheres in the latter third of the chain tend to space out separately.

A study of unsteady forces at low Reynolds number: a strong interaction theory for the coaxial settling of three or more spheres

https://hal.archives-ouvertes.fr/hal-01668427/document

Robert Pfeffer

Papers

Acute hemorrhagic pancreatitis; report of a case with cortisone treatment.

Mixing of nano-particles by rapid expansion of high-pressure suspensions

Removal of Oil from Water by Inverse Fluidization of Aerogels

A study of unsteady forces at low Reynolds number: a strong interaction theory for the coaxial settling of three or more spheres

Extraction and precipitation particle coating using supercritical CO2