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Fluid kinetic

Tsutomu Nomura, Munetaka Ushio, Kenji Kondo, Shigeru Kikuchi
OBJECTIVE: The purpose of this research is to examine the changes in nasal airflow dynamics before and after the nasal perforation repair. METHODS: Three dimensional (3D) models of the nasal cavity before and after septal perforation repair was reconstructed using preoperative and postoperative computed tomography (CT) images of a patient. The numerical simulation was carried out using ANSYS CFX V15.0. Pre- and post-operative models were compared by their velocity, pressure (P), pressure gradient (PG), wall shear (WS), shear strain rate (SSR) and turbulence kinetic energy (TKE) in three plains...
March 13, 2018: Auris, Nasus, Larynx
Alexandre P Solon, Joakim Stenhammar, Michael E Cates, Yariv Kafri, Julien Tailleur
Motility-induced phase separation (MIPS) arises generically in fluids of self-propelled particles when interactions lead to a kinetic slowdown at high densities. Starting from a continuum description of scalar active matter akin to a generalized Cahn-Hilliard equation, we give a general prescription for the mean densities of coexisting phases in flux-free steady states that amounts, at a hydrodynamics scale, to extremizing an effective free energy. We illustrate our approach on two well-known models: self-propelled particles interacting either through a density-dependent propulsion speed or via direct pairwise forces...
February 2018: Physical Review. E
Supratik Banerjee, Alexei G Kritsuk
Three-dimensional, compressible, magnetohydrodynamic turbulence of an isothermal, self-gravitating fluid is analyzed using two-point statistics in the asymptotic limit of large Reynolds numbers (both kinetic and magnetic). Following an alternative formulation proposed by Banerjee and Galtier [Phys. Rev. E 93, 033120 (2016)2470-004510.1103/PhysRevE.93.033120; J. Phys. A: Math. Theor. 50, 015501 (2017)1751-811310.1088/1751-8113/50/1/015501], an exact relation has been derived for the total energy transfer. This approach results in a simpler relation expressed entirely in terms of mixed second-order structure functions...
February 2018: Physical Review. E
E Lázaro-Lázaro, J A Moreno-Razo, M Medina-Noyola
Upon compression, the equilibrium hard-sphere liquid [pair potential uHS (r)] freezes at a packing fraction ϕf = 0.494 or, if crystallization is prevented, becomes metastable up to its glass transition at ϕg ≈ 0.58. Throughout the fluid regime (ϕ < ϕg ), we are, thus, certain that this model liquid does not exhibit any form of kinetic arrest. If, however, a small portion of these spheres (packing fraction ϕ2 ≪ ϕ) happen to ignore each other [u22 (r) = 0] but do not ignore the remaining "normal" hard spheres [u12 (r) = u21 (r) = u11 (r) = uHS (r)], whose packing fraction is thus ϕ1 = ϕ - ϕ2 , they run the risk of becoming dynamically arrested before they demix from the "normal" particles...
March 14, 2018: Journal of Chemical Physics
Pouyan Ebrahimi, Javier Vilcáez
This research aimed to elucidate the effect of brine salinity and guar gum on the sorption and transport of Ba in dolomite rocks collected from the Arbuckle formation in Oklahoma, USA. Guar gum represents the most important organic additive used in viscosified fracturing fluids, and Ba constitutes the most common and abundant heavy metal found in unconventional oil and gas (UOG) wastewater. Batch experiments conducted using powdered dolomite rocks (500-600 μm particle size) revealed that at brine salinities of UOG wastewater, chloro-complexation reactions between Ba and Cl ions and pH changes that results from dolomite dissolution are the controlling factors of Ba sorption on dolomite...
March 12, 2018: Journal of Environmental Management
Ilsong Lee, Sung-Hyun Kim, Muruganantham Rethinasabapathy, Yuvaraj Haldorai, Go-Woon Lee, Sang Rak Choe, Sung-Chan Jang, Sung-Min Kang, Young-Kyu Han, Changhyun Roh, Wan-Seob Cho, Yun Suk Huh
In the present study, we successfully synthesized a porous three-dimensional Prussian blue-cellulose aerogel (PB-CA) composite and used it as a decorporation agent for the selective removal of ingested cesium ions (Cs+ ) from the gastrointestinal (GI) tract. The safety of the PB-CA composite was evaluated through an in vitro cytotoxicity study using macrophage-like THP-1 cells and Caco-2 intestinal epithelial cells. The results revealed that the PB-CA composite was not cytotoxic. An adsorption study to examine the efficiency of the decorporation agent was conducted using a simulated intestinal fluid (SIF)...
March 14, 2018: Scientific Reports
Elio Emilio Gonzo, Stefan Wuertz, Veronica B Rajal
Biofilm systems can be modeled using a variety of analytical and numerical approaches, usually by making simplifying assumptions regarding biofilm heterogeneity and activity as well as effective diffusivity. Inhibition kinetics, albeit common in experimental systems, are rarely considered and analytical approaches are either lacking or consider effective diffusivity of the substrate and the biofilm density to remain constant. To address this obvious knowledge gap an analytical procedure to estimate the effectiveness factor (dimensionless substrate mass flux at the biofilm-fluid interface) was developed for a continuum heterogeneous biofilm with multiple limiting-substrate Monod kinetics to different types of inhibition kinetics...
2018: NPJ Biofilms and Microbiomes
Zhiyuan Sun, Dmitry N Basov, Michael M Fogler
A general relation is derived between the linear and second-order nonlinear ac conductivities of an electron system in the hydrodynamic regime of frequencies below the interparticle scattering rate. The magnitude and tensorial structure of the hydrodynamic nonlinear conductivity are shown to differ from their counterparts in the more familiar kinetic regime of higher frequencies. Due to universality of the hydrodynamic equations, the obtained formulas are valid for systems with an arbitrary Dirac-like dispersion, ranging from solid-state electron gases to free-space plasmas, either massive or massless, at any temperature, chemical potential, or space dimension...
March 12, 2018: Proceedings of the National Academy of Sciences of the United States of America
Panneerselvam Ranganathan, Sivaraman Savithri
Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal liquefaction of Nannochloropsis sp. microalgae in a lab-scale continuous plug-flow reactor to understand the fluid dynamics, heat transfer, and reaction kinetics in a HTL reactor under hydrothermal condition. The temperature profile in the reactor and the yield of HTL products from the present simulation are obtained and they are validated with the experimental data available in the literature. Furthermore, the parametric study is carried out to study the effect of slurry flow rate, reactor temperature, and external heat transfer coefficient on the yield of products...
February 21, 2018: Bioresource Technology
Timotheus K T Wolterbeek, Amir Raoof
Defects along wellbore interfaces constitute potential pathways for CO2 to leak from geological storage systems. In previous experimental work, we demonstrated that CO2 -induced reaction over length-scales of several meters can lead to self-sealing of such defects. In the present work, we develop a reactive transport model that, on the one hand, enables μm-mm scale exploration of reactions along debonding defects and, on the other hand, allows simulation of the large, 6 m-long samples used in our experiments...
March 8, 2018: Environmental Science & Technology
Federico Canè, Benedict Verhegghe, Matthieu De Beule, Philippe B Bertrand, Rob J Van der Geest, Patrick Segers, Gianluca De Santis
With cardiovascular disease (CVD) remaining the primary cause of death worldwide, early detection of CVDs becomes essential. The intracardiac flow is an important component of ventricular function, motion kinetics, wash-out of ventricular chambers, and ventricular energetics. Coupling between Computational Fluid Dynamics (CFD) simulations and medical images can play a fundamental role in terms of patient-specific diagnostic tools. From a technical perspective, CFD simulations with moving boundaries could easily lead to negative volumes errors and the sudden failure of the simulation...
2018: BioMed Research International
Anna Eichinger, Marta K Danecka, Tamara Möglich, Julia Borsch, Mathias Woidy, Lars Büttner, Ania C Muntau, Søren W Gersting
Metabolic control of phenylalanine concentrations in body fluids is essential for cognitive development and executive function. The hepatic phenylalanine hydroxylating system is regulated by the ratio of l-phenylalanine, which is substrate of phenylalanine hydroxylase (PAH), to the PAH cofactor tetrahydrobiopterin (BH4). Physiologically, phenylalanine availability is governed by nutrient intake, whereas liver BH4 is kept at constant level. In phenylketonuria, PAH deficiency leads to elevated blood phenylalanine and is often caused by PAH protein misfolding with loss of function...
March 5, 2018: Human Molecular Genetics
Giuseppe Scherillo, Valerio Loianno, Davide Pierleoni, Rosario Esposito, Antonio Brasiello, Matteo Minelli, Ferruccio Doghieri, Giuseppe Mensitieri
Atactic polystyrene, as reported in a recent contribution by our group, displays a marked change in glass transition when exposed to toluene vapor due to plasticization associated to vapor sorption within the polymer. The dependence of glass transition temperature of the polymer-penetrant mixture on the pressure of toluene vapor is characterized by the so called 'retrograde vitrification' phenomenon, in that, at a constant pressure, a rubber to glass transition occurs by increasing the temperature. In this contribution, we have used a theoretical approach, based on non-random lattice fluid thermodynamic model for the polymer-toluene mixture, to predict the state of this system, i...
March 2, 2018: Journal of Physical Chemistry. B
Kanchan Garai, Ammon E Posey, Xinyi Li, Joel N Buxbaum, Rohit V Pappu
Transthyretin (TTR) is a homotetrameric protein that is found in the plasma and cerebrospinal fluid. Dissociation of TTR tetramers sets off a downhill cascade of amyloid formation through polymerization of monomeric TTR. Interestingly, TTR has an additional, biologically relevant activity, which pertains to its ability to slow the progression of amyloid beta (Aβ) associated pathology in transgenic mice. In vitro, both TTR and a kinetically stable variant of monomeric TTR (M-TTR) inhibit the fibril formation of Aβ1-40/42 molecules...
March 2, 2018: Protein Science: a Publication of the Protein Society
Ira Katz, Jacqueline Murdock, Marc Palgen, Géraldine Farjot
Under normal conditions we continuously breathe 78% nitrogen (N2 ) such that the body tissues and fluids are saturated with dissolved N2 . For normobaric medical gas administration at high concentrations, the N2 concentration must be less than that in the ambient atmosphere; therefore, nitrogen will begin to be released by the body tissues. There is a need to estimate the time needed for denitrogenation in the planning of surgical procedures. In this paper we will describe the application of a physiologically based pharmacokinetic model to denitrogenation kinetics...
October 2017: Medical Gas Research
Teresa Marggraf, Petra Ganas, Sebastian Paris, Falk Schwendicke
Sealing can arrest caries lesions. We aimed to evaluate if sealing effects and kinetics are bacterial-strain and sealing-material specific. Human dentin discs were mounted in a dual-chamber device. Caries lesions were induced chemically and contaminated with either Lactobacillus rhamnosus (LR) or Streptococcus sobrinus (SS). For (1) kinetics assessment, the initial bacterial load and the sealing period were varied, and lesions sealed using a self-etch adhesive and composite. For (2) comparing materials, six sealing protocols (#1-#6) were evaluated: 1# Self-etch adhesive plus composite placed without a liner, or #2 calcium hydroxide, or #3 mineral trioxide aggregate, or #4 Biodentine liners; #5 antibacterial adhesive plus composite; #6 glass ionomer cement...
February 28, 2018: Scientific Reports
Masanori Tachikawa, Reiji Yokoyama, Shin-Ichi Akanuma, Ken-Ichi Hosoya
Regulating γ-aminobutyric acid (GABA) uptake transport on the plasma membranes is required for its efficient clearance from the brain interstitial fluid. The purpose of this study was to clarify the assembly of taurine transporter (TauT/Slc6a6) and PSD-95/Disc-large/Zo-1 (PDZ) domain of Na+ -H+ exchanger regulatory factor 1 (NHERF1) as a regulatory mechanism of TauT-mediated GABA transport activity. In vitro glutathione S-transferase (GST)-pull down assay and immunoblotting with anti-NHERF1 antibody revealed that NHERF1 protein was present in rat brain lysates as the binding protein of the GST-fusion TauT C-terminal protein with the PDZ-binding ETMM motif but not its corresponding deletion mutant lacking the motif...
2018: Biological & Pharmaceutical Bulletin
Kate E Hawkins, Michelangelo Corcelli, Kate Dowding, Anna M Ranzoni, Filipa Vlahova, Kwan-Leong Hau, Avina Hunjan, Donald Peebles, Pierre Gressens, Henrik Hagberg, Paolo de Coppi, Mariya Hristova, Pascale V Guillot
Human mesenchymal stem cells (MSCs) have huge potential for regenerative medicine. In particular, the use of pluripotent stem cell-derived mesenchymal stem cells (PSC-MSCs) overcomes the hurdle of replicative senescence associated with the in vitro expansion of primary cells and has increased therapeutic benefits in comparison to the use of various adult sources of MSCs in a wide range of animal disease models. On the other hand, fetal MSCs exhibit faster growth kinetics and possess longer telomeres and a wider differentiation potential than adult MSCs...
February 28, 2018: Stem Cells Translational Medicine
Alon Nissan, Brian Berkowitz
We investigate the effects of high fluid velocities on flow and tracer transport in heterogeneous porous media. We simulate fluid flow and advective transport through two-dimensional pore-scale matrices with varying structural complexity. As the Reynolds number increases, the flow regime transitions from linear to nonlinear; this behavior is controlled by the medium structure, where higher complexity amplifies inertial effects. The result is, nonintuitively, increased homogenization of the flow field, which leads in the context of conservative chemical transport to less anomalous behavior...
February 2, 2018: Physical Review Letters
Yu-Chiao Yang, Ming-Chi Wei
This study compared the use of ultrasound-assisted supercritical CO2 (USC-CO2 ) extraction to obtain apigenin-rich extracts from Scutellaria barbata D. Don with that of conventional supercritical CO2 (SC-CO2 ) extraction and heat-reflux extraction (HRE), conducted in parallel. This green procedure yielded 20.1% and 31.6% more apigenin than conventional SC-CO2 extraction and HRE, respectively. Moreover, the extraction time required by the USC-CO2 procedure, which used milder conditions, was approximately 1.9 times and 2...
June 30, 2018: Food Chemistry
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