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Complex Fluids (complex + fluid)
Selected AbstractsApproximation of magnetic behavior of complex nanomagnetic materials, using the "P " curves for structural characterization of magnetic suspensionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008N. C. Popa Abstract The "P " curves for the structural characterization of magnetic nanoparticles suspensions (complex fluids, complex powders, complex composite materials, or living biological materials having magnetic properties) are the graphical representation of the first derivative (relative to the magnetic field strength H) of the magnetization curve relative to its saturation magnetization. In the case of the above materials, the magnetic properties are conferred to various carrier liquids by artificially integrating in their structure ferromagnetic particles of different sizes. The magnetic properties are usually shown by the hysteresis curve. The structure can be seen by (electronic) micrography. The P curves offer another possibility to determine the structure of the magnetic component of a complex fluid by numerical analysis of the magnetization curve experimentally obtained. Starting from these P curves, the paper presents the possibility to approximate the magnetic behavior of these complex nanomagnetic materials. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] In Pursuit of Zero: Polymer Brushes that Resist the Adsorption of ProteinsADVANCED MATERIALS, Issue 23 2009Angus Hucknall Abstract Protein resistant or "non-fouling" surfaces are of great interest for a variety of biomedical and biotechnology applications. This article briefly reviews the development of protein resistant surfaces, followed by recent research on a new methodology to fabricate non-fouling surfaces by surface-initiated polymerization. We show that polymer brushes synthesized by surface-initiated polymerization that present short oligo(ethylene glycol) side chains are exceptionally resistant to protein adsorption and cell adhesion. The importance of the protein and cell resistance conferred by these polymer brushes is illustrated by their use as substrates for the fabrication of antibody microarrays that exhibit femtomolar limits of detection in complex fluids such as serum and blood with relaxed requirements for intermediate wash steps. This example highlights the important point that the reduction in background noise afforded by protein-resistant surfaces can greatly simplify the development of ultrasensitive heterogeneous, surface-based clinical and proteomic assays with increased sensitivity and utility. [source] The effect of water-soluble polymers on rheology of microfibrillar cellulose suspension and dynamic mechanical properties of paper sheetJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Arja-Helena Vesterinen Abstract Rheological properties of fiber/polymer suspensions and dynamic mechanical analysis (DMA) of paper sheets containing the same polymers were measured. Correlations between viscoelastic properties of suspensions and strength of paper sheet are presented. Rheological properties of suspensions of microfibrillar cellulose (MFC) and a set of water soluble polymers were measured. Rheological properties of these complex fluids vary considerably depending on the added polymer. A suspension of fiber and carboxymethyl cellulose (CMC) exhibits a viscosity higher than the sum of the viscosity of the individual components in the suspension. In contrast, when cationic starch (CS) is used together with the fiber, the yielding behavior rather than the viscosity is characteristic of the suspension. Dynamic mechanical properties of paper sheets containing CMC or CS as additives were studied at different humidity levels. Different yielding behavior observed in oscillatory rheology can be correlated with straining behavior in dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Techniques for visualization of cavern boundaries in opaque industrial mixing systemsAICHE JOURNAL, Issue 11 2009M. J. H. Simmons Abstract In the agitation of complex fluids, the avoidance of caverns is essential for successful blending. Electrical resistance tomography (ERT) and positron emission projection imaging, which can both image within opaque fluids, have been assessed for visualization of cavern boundaries. A vessel of diameter, T = 154 mm, equipped with a single 57 mm diameter six bladed 45° down pumping pitched blade disc turbine formed the test system. The fluid used was aqueous solution of carbopol 940. Both techniques were used to detect and image caverns at Re from 20,86.6 and compared with optical images. Reasonable agreement on the maximum cavern heights and widths were obtained, with the taller and narrower caverns obtained via 3D ERT measurements being attributed to artifacts of the method and interactions between the polymer and tracer. Caverns were also detectable using a robust linear ERT array, which has potential for use within industrial systems. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Block Copolymers Under Shear FlowMACROMOLECULAR THEORY AND SIMULATIONS, Issue 4 2005Igor Rychkov Abstract Summary: Microphase separation transition in block copolymer melts and solutions in equilibrium and under shear flow is reviewed. The non-equilibrium molecular dynamics (NEMD) computer simulation methodology is presented in detail including the derivation of the SLLOD equations of motion, Gaussian thermostat, and operator-splitting symplectic integrators. Results of our recent NEMD computer simulation studies of diblock copolymers in a selective solvent under shear flow are presented. Shear-dependent structural, rheological, and microscopical properties are described. New phase transitions are discovered. The parallel-perpendicular orientational transition in a weak-strong flow is revealed. Theoretical approaches are reviewed including the Edwards Hamiltonian, Landau-Ginzburg model, self-consistent mean field theory, field-theoretic simulation, as well as the time-dependent Landau-Ginzburg framework and its application to the studies of complex fluids. [source] Approximation of magnetic behavior of complex nanomagnetic materials, using the "P " curves for structural characterization of magnetic suspensionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008N. C. Popa Abstract The "P " curves for the structural characterization of magnetic nanoparticles suspensions (complex fluids, complex powders, complex composite materials, or living biological materials having magnetic properties) are the graphical representation of the first derivative (relative to the magnetic field strength H) of the magnetization curve relative to its saturation magnetization. In the case of the above materials, the magnetic properties are conferred to various carrier liquids by artificially integrating in their structure ferromagnetic particles of different sizes. The magnetic properties are usually shown by the hysteresis curve. The structure can be seen by (electronic) micrography. The P curves offer another possibility to determine the structure of the magnetic component of a complex fluid by numerical analysis of the magnetization curve experimentally obtained. Starting from these P curves, the paper presents the possibility to approximate the magnetic behavior of these complex nanomagnetic materials. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] LDA Velocity Measurements of High-Viscosity Fluids in Mixing Vessel with Vane Geometry ImpellerTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2007Lidija Slemenik Perse Abstract The object of this work was to measure the velocity field in non-Newtonian fluids inside mixing vessel. The six-bladed vane rotor used for mixing was designed from rotating vane geometry of a sensor system, commonly used for rheometrical measurements of complex fluids (Barnes and Nguyen, J. Non-Newtonian Fluid Mech. 98, 1-14 (2001); Schramm, 1994). During mixing, the viscosity was determined by measuring the torque at different impeller speeds, and compared to rheologically obtained shear dependent viscosity. The velocity field was determined by LDA measurements at twelve places inside mixing vessel. It was observed that axial and radial component of the velocity were insignificant at all measurement points. On the other hand, the results showed the periodic nature of tangential component of the velocity, which was confirmed with computer-aided visualization method. Ce travail avait pour objectif de mesurer le champ de vitesse dans des fluides non newtoniens dans un réservoir de mélange. Le rotor à six pales utilisé pour le mélange a été conçu d'après la géométrie des ailettes rotatives d'un système de senseurs, communément utilisés dans les mesures rhéométriques de fluides complexes (Barnes and Nguyen, J. Non-Newtonian Fluid Mech. 98, 1-14 (2001); Schramm, 1994). Lors du mélange, on a déterminé la viscosité en mesurant le couple à différentes vitesses de turbine, puis on l'a comparée à la viscosité de cisaillement obtenue rhéologiquement. Le champ de vitesse a été déterminé par des mesures LDA à douze positions dans le réservoir de mélange. On a observé que la composante axiale et radiale de la vitesse était négligeable pour tous les points de mesure. Par ailleurs, les résultats montrent la nature périodique de la composante tangentielle de la vitesse, ce qui est confirmé par une méthode de visualisation assistée par ordinateur. [source] |