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fluid structure interaction

Bo Yang, Zi-Xiang Hu, Ching Hua Lee, Z Papić
We generalize the notion of Haldane pseudopotentials to anisotropic fractional quantum Hall (FQH) systems that are physically realized, e.g., in tilted magnetic field experiments or anisotropic band structures. This formalism allows us to expand any translation-invariant interaction over a complete basis, and directly reveals the intrinsic metric of incompressible FQH fluids. We show that purely anisotropic pseudopotentials give rise to new types of bound states for small particle clusters in the infinite plane, and can be used as a diagnostic of FQH nematic order...
April 7, 2017: Physical Review Letters
Boyce E Griffith, Xiaoyu Luo
The immersed boundary method is an approach to fluid-structure interaction that uses a Lagrangian description of the structural deformations, stresses, and forces along with an Eulerian description of the momentum, viscosity, and incompressibility of the fluid-structure system. The original immersed boundary methods described immersed elastic structures using systems of flexible fibers, and even now, most immersed boundary methods still require Lagrangian meshes that are finer than the Eulerian grid. This work introduces a coupling scheme for the immersed boundary method to link the Lagrangian and Eulerian variables that facilitates independent spatial discretizations for the structure and background grid...
April 20, 2017: International Journal for Numerical Methods in Biomedical Engineering
Michele Pozzoli, Daniela Traini, Paul M Young, Maria B Sukkar, Fabio Sonvico
OBJECTIVE: The aim of this work was to develop an amorphous solid dispersions/solutions (ASD) of a poorly soluble drug, Budesonide (BUD) with a novel polymer Soluplus(®) (BASF, Germany) using a freeze-drying technique, in order to improve dissolution and absorption through the nasal route. SIGNIFICANCE: The small volume of fluid present in the nasal cavity limits the absorption of a poorly soluble drug. Budesonide is a corticosteroid, practically insoluble, and normally administered as a suspension-based nasal spray...
April 20, 2017: Drug Development and Industrial Pharmacy
Gabriella Ortore, Adriano Martinelli
Transthyretin (TTR) is the primary carrier for thyroxine (T4) in cerebrospinal fluid and a secondary carrier in blood. TTR is a stable homotetramer, but certain factors, genetic or environmental, could promote its degradation to form amyloid fibrils. A docking study in the wild-type TTR crystal structures was planned; our aim was to design new ligands able to inhibit TTR fibril formation. The computational protocol was thought to overcome the multiple binding modes of the ligands induced by the specularity of the TTR binding site and by the pseudosymmetry of the site pockets, which generally weaken such structure-based studies...
April 19, 2017: ChemMedChem
Atul S Bharadwaj, Yashwant Singh
We develop a theory to describe solid-solid phase transitions. The density functional formalism of classical statistical mechanics is used to find an exact expression for the difference in the grand thermodynamic potentials of the two coexisting phases. The expression involves both the symmetry conserving and the symmetry broken parts of the direct pair correlation function. The theory is used to calculate phase diagram of systems of soft spheres interacting via inverse power potentials u(r)=ε(σ/r)^{n}, where parameter n measures softness of the potential...
March 2017: Physical Review. E
Maciej Studzian, Aleksandra Szulc, Anna Janaszewska, Dietmar Appelhans, Łukasz Pułaski, Barbara Klajnert-Maculewicz
Poly(propylene imine) dendrimers of 4th generation partially modified with maltose (open shell structure, PPI-m OS) have been proposed as carriers for nucleotide anticancer drugs. The aim of this work was to provide basic insight into interactions between fluorescently labeled PPI-m dendrimer and two distinct leukemia cell models: CCRF-1301 lymphoid cell line and HL-60 myeloid cell line. We applied qualitative confocal imaging and quantitative flow cytometry, as well as trypan blue quenching and pharmacological inhibition, to investigate the course, kinetics and molecular mechanisms of internalization of nanoparticles...
April 17, 2017: Biomacromolecules
William D Piñeros, Thomas M Truskett
Using a recently introduced formulation of the ground-state inverse design problem for a targeted lattice [W. Piñeros et al., J. Chem. Phys. 144, 084502 (2016)], we discover purely repulsive and isotropic pair interactions that stabilize low-density truncated square and truncated hexagonal crystals, as well as promote their assembly in Monte Carlo simulations upon isochoric cooling from a high-temperature fluid phase. The results illustrate that the primary challenge to stabilizing very open two-dimensional lattices is to design interactions that can favor the target structure over competing stripe microphases...
April 14, 2017: Journal of Chemical Physics
C Ruscher, A N Semenov, J Baschnagel, J Farago
The physics of simple fluids in the hydrodynamic limit and notably the connection between the proper microscopic scales and the macroscopic hydrodynamical description are nowadays well understood. In particular, the three peak shape of the dynamical structure factor S(k,ω) is a universal feature, as well as the k-dependence of the peak position (∝k) and width ∝k(2), the latter accounting for the sound attenuation rate. In this paper, we present a theoretical model of monodisperse fluid, whose interactions are defined via the Voronoi tessellations of the configurations [called the Voronoi liquid and first studied in Ruscher et al...
April 14, 2017: Journal of Chemical Physics
Thomas Gibaud, C Nadir Kaplan, Prerna Sharma, Mark J Zakhary, Andrew Ward, Rudolf Oldenbourg, Robert B Meyer, Randall D Kamien, Thomas R Powers, Zvonimir Dogic
In the presence of a nonadsorbing polymer, monodisperse rod-like particles assemble into colloidal membranes, which are one-rod-length-thick liquid-like monolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal monolayer membranes form open structures with an exposed edge, thus presenting an opportunity to study elasticity of fluid sheets. Membranes assembled from single-component chiral rods form flat disks with uniform edge twist. In comparison, membranes composed of a mixture of rods with opposite chiralities can have the edge twist of either handedness...
April 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
David M Rutkowski, Orlin D Velev, Sabine H L Klapp, Carol K Hall
A major research theme in materials science is determining how the self-assembly of new generations of colloidal particles of complex shape and surface charge is guided by their interparticle interactions. In this paper, we describe results from quasi-2D Monte Carlo simulations of systems of colloidal particles with offset transversely-oriented extended dipole-like charge distributions interacting via an intermediate-ranged Yukawa potential. The systems are cooled slowly through an annealing procedure during which the temperature is lowered in discrete steps, allowing the system to equilibrate...
April 11, 2017: Soft Matter
Gergő Gyulai, Éva Kiss
HYPOTHESIS: Adsorption and localization of nanoparticles at fluid interfaces are key factors in processes like transport through membranes or emulsion stabilization. Adsorption of poly(lactic-co-glycolic acid) (PLGA) and Pluronic coated PLGA nanoparticles (NPs) were studied at three different fluid interfaces. The effect of particle surface modification and type of interface was investigated with the aim of fine tuning interfacial interaction of the nanoparticles. EXPERIMENTS: Surface tension measurements were carried out to determine the surface activity and adsorption kinetics of the particles...
March 31, 2017: Journal of Colloid and Interface Science
Yu Su, James W Swan, Roseanna N Zia
Accurate modeling of particle interactions arising from hydrodynamic, entropic, and other microscopic forces is essential to understanding and predicting particle motion and suspension behavior in complex and biological fluids. The long-range nature of hydrodynamic interactions can be particularly challenging to capture. In dilute dispersions, pair-level interactions are sufficient and can be modeled in detail by analytical relations derived by Jeffrey and Onishi [J. Fluid Mech. 139, 261-290 (1984)] and Jeffrey [Phys...
March 28, 2017: Journal of Chemical Physics
Le Wang, Amin Haghmoradi, Jinlu Liu, Shun Xi, George J Hirasaki, Clarence A Miller, Walter G Chapman
Surfactants reduce the interfacial tension between phases, making them an important additive in a number of industrial and commercial applications from enhanced oil recovery to personal care products (e.g., shampoo and detergents). To help obtain a better understanding of the dependence of surfactantproperties on molecular structure, a classical density functional theory, also known as interfacial statistical associating fluid theory, has been applied to study the effects of surfactant architecture on micelle formation and interfacial properties for model nonionic surfactant/water/oil systems...
March 28, 2017: Journal of Chemical Physics
Rajendra P Giri, Abhijit Chakrabarti, Mrinmay K Mukhopadhyay
Lateral and out-of-plane organization of cholesterol and its effect on regulating the physicochemical properties of zwitterionic phospholipid model membranes have been investigated by a pressure-area isotherm study from the Langmuir monolayer, atomic force microscopy (AFM), and X-ray reflectivity (XRR) measurements from supported binary monolayer films. The systematic isotherm studies on the Langmuir monolayer of phospholipids and the subsequent extraction of excess Gibbs free energy (ΔGexc) revealed the mechanism of cholesterol interaction and the molecular cooperativeness for different arrangements in the phospholipid model membranes...
April 17, 2017: Journal of Physical Chemistry. B
Yann Lelièvre, Pierre Legendre, Marjolaine Matabos, Steve Mihály, Raymond W Lee, Pierre-Marie Sarradin, Claudia P Arango, Jozée Sarrazin
Ocean tides and winter surface storms are among the main factors driving the dynamics and spatial structure of marine coastal species, but the understanding of their impact on deep-sea and hydrothermal vent communities is still limited. Multidisciplinary deep-sea observatories offer an essential tool to study behavioural rhythms and interactions between hydrothermal community dynamics and environmental fluctuations. Here, we investigated whether species associated with a Ridgeia piscesae tubeworm vent assemblage respond to local ocean dynamics...
April 12, 2017: Proceedings. Biological Sciences
Richard K Zimmer, Graham A Ferrier, Steven J Kim, Rachel R Ogorzalek Loo, Cheryl Ann Zimmer, Joseph A Loo
Keystone species structure ecological communities and are major determinants of biodiversity. A synthesis of research on keystone species is nonetheless missing a critical component -NDASH- the sensory mechanisms for behavioral interactions that determine population- and community-wide attributes. Here, we establish the chemosensory basis for keystone predation by sea stars (Pisaster ochraceus) on mussels. This consumer-resource interaction is prototypic of top-down driven trophic cascades. Each mussel species (Mytilus californianus and M...
April 4, 2017: Ecology
S A Flowers, S Kalamajski, L Ali, L I Björkman, J R Raj, A Aspberg, N G Karlsson, C Jin
OBJECTIVE: Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. DESIGN: Synovial fluid (SF) from arthritic patients was used to detect possible COMP-lubricin complexes by immunological methods...
April 1, 2017: Osteoarthritis and Cartilage
Joanna Szafraniec, Agata Antosik, Justyna Knapik-Kowalczuk, Mateusz Kurek, Karolina Syrek, Krzysztof Chmiel, Marian Paluch, Renata Jachowicz
Dissolution of bicalutamide processed with polyvinylpyrrolidone by either supercritical carbon dioxide or ball milling has been investigated. Various compositions as well as process parameters were used to obtain binary systems of the drug with the carrier. Thermal analysis and powder X-ray diffractometry confirmed amorphization of bicalutamide mechanically activated by ball milling and the decrease in crystallinity of the supercritical carbon dioxide-treated drug. Both methods led to reduction of particles size what was confirmed by scanning electron microscopy and laser diffraction measurements...
March 28, 2017: International Journal of Pharmaceutics
Catherine Noiriel, Damien Daval
The reactivity of carbonate and silicate minerals is at the heart of porosity and pore geometry changes in rocks injected with CO2, which ultimately control the evolution of flow and transport properties of fluids in porous and/or fractured geological reservoirs. Modeling the dynamics of CO2-water-rock interactions is challenging because of the resulting large geochemical disequilibrium, the reservoir heterogeneities, and the large space and time scales involved in the processes. In particular, there is a lack of information about how the macroscopic properties of a reservoir, e...
March 31, 2017: Accounts of Chemical Research
Anju Toor, Brett A Helms, Thomas P Russell
Structured liquids, whose 3-D morphology can adapt and respond to external stimuli, represent a revolutionary materials platform for next-generation energy technologies, such as batteries, photovoltaics, and thermoelectrics. Structured liquids can be crafted by the jamming of interfacial assemblies of nanoparticle (NP) surfactants. Due to the interactions between functional groups on nanoparticles dispersed in one liquid and polymers having complementary end-functionality dissolved in a second immiscible fluid, the anchoring of a well-defined number of polymer chains onto the NPs leads to the formation of NP-surfactants that assemble at the interface and reduce the interfacial energy...
March 30, 2017: Nano Letters
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