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fluid structure interaction

Steffen Vojacek, Katja Beese, Zayan Alhalabi, Sören Swyter, Anja Bodtke, Carola Schulzke, Manfred Jung, Wolfgang Sippl, Andreas Link
Nonpolar derivatives of heterocyclic aromatic screening hits like the non-selective sirtuin inhibitor splitomicin tend to be poorly soluble in biological fluids. Unlike sp(3) -rich natural products, flat aromatic compounds are prone to stacking and often difficult to optimize into leads with activity in cellular systems. The aim of this work was to identify anchor points for the introduction of sp(3) -rich fragments with polar functional groups into the newly discovered active (IC50  = 5 μM) but nonpolar scaffold 1,2-dihydro-3H-naphth[1,2-e][1,3]oxazine-3-thione by a molecular modeling approach...
May 26, 2017: Archiv der Pharmazie
Qinglin Hu, Xuan Bai, Guoqing Hu, Yi Y Zuo
The growing risk of human exposure to airborne nanoparticles (NPs) causes a general concern on the biosafety of nanotechnology. Inhaled NPs can deposit in the deep lung at which interacting with the pulmonary surfactant (PS). Despite the increasing study of nano-bio interactions, detailed molecular mechanisms by which inhaled NPs interact with the natural PS system remain unclear. Using coarse-grained molecular dynamics simulation, we studied the interaction between NPs and the PS system in the alveolar fluid...
May 25, 2017: ACS Nano
Michael F Brown
Membrane lipids and cellular water (soft matter) are becoming increasingly recognized as key determinants of protein structure and function. Their influences can be ascribed to modulation of the bilayer properties or to specific binding and allosteric regulation of protein activity. In this review, we first consider hydrophobic matching of the intramembranous proteolipid boundary to explain the conformational changes and oligomeric states of proteins within the bilayer. Alternatively, membranes can be viewed as complex fluids, whose properties are linked to key biological functions...
May 22, 2017: Annual Review of Biophysics
Erik A B Hughes, Liam M Grover
BACKGROUND: Calcium sulphate (CS) has been used in bone grafting since the 1800s. It has not replaced autograft as the gold standard, however, since its dissolution occurs rapidly in bodily fluids, meaning that the material cannot support long-term bone growth. Here, the polymer poly (ether ether ketone) (PEEK) was used to slow dissolution in in vitro physiological environments and augment the mechanical properties of the material. METHODS: PEEK/CS specimens were fabricated by combining powders of PEEK and CS with water, resulting in a hardening paste...
2017: Biomaterials Research
Alistair Revell, Joseph O'Connor, Abhishek Sarkar, Cuicui Li, Julien Favier, Laura Kamps, Christoph Brücker
The fluid-structure interaction mechanisms of a coating composed of flexible flaps immersed in a periodically oscillating channel flow is here studied by means of numerical simulation, employing the Euler-Bernoulli equations to account for the flexibility of the structures. A set of passively actuated flaps have previously been demonstrated to deliver favourable aerodynamic impact when attached to a bluff body undergoing periodic vortex shedding. As such, the present configuration is identified to provide a useful test-bed to better understand this mechanism, thought to be linked to experimentally observed travelling waves...
2017: Meccanica
Ishtiaq A Chaudhry, Tipu Sultan, Farrukh A Siddiqui, M Farhan, M Asim
ABSTRACT: A series of experiments involving the particle image velocimetry technique are carried out to analyse the quantitative effectiveness of the synthesized vortical structures towards actual flow separation control. The streamwise vortices are synthesized from the synthetic jet actuator and introduced into the attached and separating boundary layer developed on the flat plate surface. Two types of actuators with different geometrical set-ups are used to analyse the evolution of vortical structures in the near wall region and their impact towards achieving separation delay in the boundary layer...
2017: Journal of Visualization
Peet Cremer, Marco Heinen, Andreas Menzel, Hartmut Lowen
Ferrogels consist of magnetic colloidal particles embedded in an elastic polymer matrix. As a consequence, their structural and rheological properties are governed by a competition between magnetic particle-particle interactions and mechanical matrix elasticity. Typically the particles are permanently fixed within the matrix, which makes them distinguishable by their positions. Over time, particle neighbors do not change due to the fixation by the matrix. Here we present a classical density functional approach for such ferrogels...
May 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Péter Gurin, Gerardo Odriozola, Szabolcs Varga
We examine the phase behavior of a quasi-one-dimensional system of hard squares with side-length σ, where the particles are confined between two parallel walls and only nearest-neighbor interactions occur. As in our previous work [Gurin, Varga, and Odriozola, Phys. Rev. E 94, 050603 (2016)]2470-004510.1103/PhysRevE.94.050603, the transfer operator method is used, but here we impose a restricted orientation and position approximation to yield an analytic description of the physical properties. This allows us to study the parallel fluid-like to zigzag solid-like structural transition, where the compressibility and heat capacity peaks sharpen and get higher as H→H_{c}=2sqrt[2]-1≈1...
April 2017: Physical Review. E
Hanae Kataoka, Akira Ushiyama, Yoshihiro Akimoto, Sachie Matsubara, Hayato Kawakami, Takehiko Iijima
BACKGROUND: The endothelial surface layer (ESL) regulates vascular permeability to maintain fluid homeostasis. The glycocalyx (GCX), which has a complex and fragile ultrastructure, is an important component of the ESL. Abnormalities of the GCX have been hypothesized to trigger pathological hyperpermeability. Here, we report an integrated in vivo analysis of the morphological and functional properties of the GCX in a vital organ. METHODS: We examined the behavior of the ESL and GCX, using both electron microscopy (EM) and intravital microscopy (IVM)...
May 11, 2017: Anesthesia and Analgesia
Yuanji Xu, Min Liu, Ping Zheng, Xiangrong Chen, Jin-Guang Cheng, Jianlin Luo, Wenhui Xie, Yi-Feng Yang
Manganese monophosphide (MnP) shows complicated magnetic states varying with both temperature and pressure. We calculate the magnetic and electronic structures of MnP at different pressures using first-principles methods and obtain spiral ground states whose propagation vector changes from the c-axis at low pressure to the b-axis at high pressure. In between, we find a ferromagnetic state, as observed in the experimental phase diagram. The propagation vector of the spiral states is found to vary nonmonotonically with pressure, consistent with neutron measurements...
June 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Tyler J Perlenfein, Jacob D Mehlhoff, Regina M Murphy
Cystatin C (CysC) is a versatile and ubiquitously-expressed member of the cysteine protease inhibitor family that is present at notably high concentration in cerebrospinal fluid. Under mildly denaturing conditions, CysC forms inactive domain-swapped dimers. A destabilizing mutation, L68Q, increases the rate of domain-swapping and causes a fatal amyloid disease, Hereditary Cystatin C Amyloid Angiopathy. Wild-type (wt) CysC will also aggregate into amyloid fibrils under some conditions. Propagated domain swapping has been proposed as the mechanism by which CysC fibrils grow...
May 9, 2017: Journal of Biological Chemistry
Claudio Ronco
The low water permeability feature of original cellulosic membranes was considered an advantage in the absence of dialysis equipment that are capable of controlling water removal. The advent of ultrafiltration control systems led to the development and use of high-flux (HF) membranes that allowed improved middle molecule removal including β-2 microglobulin. Further advances in technology allowed better control over the structure and permeability of membranes. Different polymers and improved spinning modalities led to significant advances in solute removal and hemocompatibility...
May 10, 2017: Blood Purification
Hanlin Liu, Oscar Curet
Many aquatic animals propelled by elongated undulatory fins can perform complex maneuvers and swim with high efficiency at low speeds. In this type of swimming, one or multiple waves travel along the flexible fin that is composed of fin rays (for bony fish) interconnected with an elastic membrane. In this work, we explore the potential benefits or disadvantages of using passive fin motion based on the coupling of fluid-structure interaction and the elasto-mechanical responses of the undulatory fin. The motivation of this work is to understand how an under-actuated undulating fin can modify its active and passive fin motion to effectively control the hydrodynamic forces and propulsive efficiency...
May 8, 2017: Bioinspiration & Biomimetics
Brittany E Givens, Nina D Diklich, Jennifer Fiegel, Vicki H Grassian
Bovine serum albumin (BSA) adsorbed on amorphous silicon dioxide (SiO2) nanoparticles was studied as a function of pH across the range of 2 to 8. Aggregation, surface charge, surface coverage, and protein structure were investigated over this entire pH range. SiO2 nanoparticle aggregation is found to depend upon pH and differs in the presence of adsorbed BSA. For SiO2 nanoparticles truncated with hydroxyl groups, the largest aggregates were observed at pH 3, close to the isoelectric point of SiO2 nanoparticles, whereas for SiO2 nanoparticles with adsorbed BSA, the aggregate size was the greatest at pH 3...
May 3, 2017: Biointerphases
Yonny Mauricio Muñoz-Muñoz, Chieh-Ming Hsieh, Jadran Vrabec
The three binary mixtures cyclohexane + benzene, cyclohexanol + phenol and cyclohexylamine + aniline exhibit qualitatively different vapor-liquid phase behavior, i.e. azeotropic with pressure maximum, azeotropic with pressure minimum and zeotropic, respectively. Employing molecular modeling and simulation, the COSMO-SAC model and a cubic equation of state, the root of these effects is studied on the basis of phase equilibria, excess properties for volume, enthalpy and Gibbs energy as well as microscopic structure...
May 2, 2017: Journal of Physical Chemistry. B
Artee Bansal, Arjun Valiya Parambathu, D Asthagiri, Kenneth R Cox, Walter G Chapman
We present a theory to predict the structure and thermodynamics of mixtures of colloids of different diameters, building on our earlier work [A. Bansal et al., J. Chem. Phys. 145, 074904 (2016)] that considered mixtures with all particles constrained to have the same size. The patchy, solvent particles have short-range directional interactions, while the solute particles have short-range isotropic interactions. The hard-sphere mixture without any association site forms the reference fluid. An important ingredient within the multi-body association theory is the description of clustering of the reference solvent around the reference solute...
April 28, 2017: Journal of Chemical Physics
Giulia Luraghi, Wei Wu, Francesco De Gaetano, Josè Felix Rodriguez Matas, Geoff D Moggridge, Marta Serrani, Joanna Stasiak, Maria Laura Costantino, Francesco Migliavacca
Bio-inspired polymeric heart valves (PHVs) are excellent candidates to mimic the structural and the fluid dynamic features of the native valve. PHVs can be implanted as prosthetic alternative to currently clinically used mechanical and biological valves or as potential candidate for a minimally invasive treatment, like the transcatheter aortic valve implantation. Nevertheless, PHVs are not currently used for clinical applications due to their lack of reliability. In order to investigate the main features of this new class of prostheses, pulsatile tests in an in-house pulse duplicator were carried out and reproduced in silico with both structural Finite-Element (FE) and Fluid-Structure interaction (FSI) analyses...
April 19, 2017: Journal of Biomechanics
Y H Boon, M Raoov, N N M Zain, S Mohamad, H Osman
The growth in driving force and popularity of cyclodextrin (CDs) and ionic liquids (ILs) as promising materials in the field of analytical chemistry has resulted in an exponentially increase of their exploitation and production in analytical chemistry field. Cyclodextrins belong to the family of cyclic oligosaccharides composing of α-(1,4) linked glucopyranose subunits and possess a cage-like supramolecular structure. This structure enables chemical reactions to proceed between interacting ions, radical or molecules in the absence of covalent bonds...
April 28, 2017: Critical Reviews in Analytical Chemistry
Cameron L C Smith, Anil H Thilsted, Jonas N Pedersen, Tomas H Youngman, Julia C Dyrnum, Nicolai A Michaelsen, Rodolphe Marie, Anders Kristensen
The ability to handle single, free molecules in lab-on-a-chip systems is key to the development of advanced biotechnologies. Entropic confinement offers passive control of polymers in nanofluidic systems by locally asserting a molecule's number of available conformation states through structured landscapes. Separately, a range of plasmonic configurations have demonstrated active manipulation of nano-objects by harnessing concentrated electric fields. The integration of these two independent techniques promises a range of sophisticated and complementary functions to handle, for example, DNA, but numerous difficulties, in particular, conflicting requirements of channel size, have prevented progress...
April 28, 2017: ACS Nano
Christopher Ness, Zhongyang Xing, Erika Eiser
The viscosity of a dense suspension has contributions from hydrodynamics and particle interactions, both of which depend upon the flow-induced arrangement of particles into fragile structures. Here, we study the response of nearly hard sphere suspensions to oscillatory shear using simulations and experiments in the athermal, non-inertial limit. Three distinct regimes are observed as a function of the strain amplitude γ0. For γ0 < 10(-1), initially non-contacting particles remain separated and the suspension behaves similarly to a Newtonian fluid, with the shear stress proportional to the strain rate, and the normal stresses close to zero...
April 28, 2017: Soft Matter
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