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Fluid kinetics

Mauro Ursino, Gabriele Donati
Potassium balance is a difficult task in hemodialysis: low potassium in the dialysate is associated with a high risk of sudden cardiac death, whereas excessive dialysate potassium may provoke insufficient removal and hyperkalemia. A better understanding of the problem can be achieved with the use of mathematical models of solute kinetics. This study is aimed at presenting an improved model of solute kinetics and fluid shifts during hemodialysis. It comprises a 2-compartment (intracellular and extracellular) description of sodium, potassium, and urea, including volume fluid shifts induced by osmotic forces...
2017: Contributions to Nephrology
Marcello Sega, Balázs Fábián, Pal Jedlovszky
Surface tension, the tendency of fluid interfaces to behave elastically and minimize their surface, is routinely calculated as the difference between the lateral and normal components of the pressure or, invoking isotropy in momentum space, of the virial tensor. Here we show that the anisotropy of the kinetic energy tensor close to a liquid/vapour interface can be responsible for a large part of its surface tension (about 15 % for water, independently on temperature).
May 23, 2017: Journal of Physical Chemistry Letters
Muhammad Shoaib, Aamer Saeed, Muhammad Saif Ur Rahman, Muhammad Moazzam Naseer
For treating bone cancer, controlled drug delivery is an important strategy. Bioactive scaffolds are widely used biomaterials due to their usefulness in localized drug delivery. The aim of this study was to develop mesoporous bioglass (MBG) with improved bioactivity and controllable drug delivery rate. By using pluronic 123 (P123) as a template, a facile sol-gel route was employed for the synthesis of MBG nanoparticles (NPs). The composition of the prepared sample was estimated by using energy dispersive X-ray spectroscopy (EDX)...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Razina Z Seeni, Xiaojun Yu, Hao Chang, Peng Chen, Linbo Liu, Chenjie Xu
In recent years, polymeric microneedles (MNs) have attracted keen interests among researchers for their applicability in transdermal drug delivery and interstitial skin fluid (ISF) extraction. When design and characterize such devices, it is critical to monitor their real-time in vitro and in vivo performances to optimize the desired effects, yet most of the existing methods are incapable of such functions. To address this unmet need, we develop a real-time non-invasive imaging methodology by integrating iron oxide (Fe3O4) nanoparticles into polymeric MNs to enhance image contrast for micro-optical coherence tomography (µOCT) imaging...
May 22, 2017: ACS Applied Materials & Interfaces
Volker Strenger, Fedja Farowski, Carsten Müller, Nora Hofer, Hans Jürgen Dornbusch, Daniela Sperl, Herwig Lackner, Martin Benesch, Christian Urban
The kinetics of caspofungin (CAS) in cerebrospinal fluid (CSF) following intravenous (i.v.) administration has been studied exclusively in animal models. However, human data are missing so far. In this study, 13 CSF samples were obtained at different time points following i.v. infusion of CAS in ten paediatric haemato-/oncological patients (age range 1.0-14.2 years, median 8.6 years) without signs of central nervous system (CNS) infection (n = 10 samples) or with infectious meningitis (n = 3 samples). Serum samples were obtained concurrently...
May 17, 2017: International Journal of Antimicrobial Agents
Deboki Naskar, Ananta K Ghosh, Mahitosh Mandal, Piyali Das, Samit K Nandi, Subhas C Kundu
In recent years the potential application of nanocomposite biomaterials in tissue engineering field is gaining importance because of the combined features of all the individual components. A bottom-up approach is acquired in this study to recreate the bone microenvironment. The regenerated silk protein fibroin obtained from nonmulberry tropical tasar Antheraea mylitta species is reinforced with functionalized carbon nano fiber (CNF) and the composite sponges are fabricated using facile green aqueous based method...
May 10, 2017: Biomaterials
I L Semenov
A one-dimensional fluid model for ions in weakly ionized plasma is proposed. The model differs from the existing ones in two aspects. First, a more accurate approximation of the collision terms in the fluid equations is suggested. For this purpose, the results obtained using the Monte Carlo kinetic model of the ion swarm experiments are considered. Second, the ion energy equation is taken into account. The fluid equations are closed using a simple model of the ion velocity distribution function. The accuracy of the fluid model is examined by comparing with the results of particle-in-cell Monte Carlo simulations...
April 2017: Physical Review. E
Peng Wen, Kun Feng, Huan Yang, Xiao Huang, Min-Hua Zong, Wen-Yong Lou, Ning Li, Hong Wu
A novel core-shell structured nanofilm for the delivery of protein to the colon was developed by coaxial electrospinning using bovine serum albumin (BSA) as protein model. Firstly, the BSA-loaded chitosan nanoparticle was prepared by ionic gelation, and then the coaxial nanofilm was fabricated using alginate as shell layer and the BSA-loaded chitosan nanoparticle as core layer. Scanning electron microscopy analysis showed that the obtained nanofilm exhibited a smooth surface, and the core-shell structure was evidenced by the aid of transmission electron microscopy...
August 1, 2017: Carbohydrate Polymers
Pedro Lopes, Rita F Carvalho, Jorge Leandro
Numerical studies regarding the influence of entrapped air on the hydraulic performance of gullies are nonexistent. This is due to the lack of a model that simulates the air-entrainment phenomena and consequently the entrapped air. In this work, we used experimental data to validate an air-entrainment model that uses a Volume-of-Fluid based method to detect the interface and the Shear-stress transport k-ω turbulence model. The air is detected in a sub-grid scale, generated by a source term and transported using a slip velocity formulation...
May 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
David C Florian, Michael A Melia, Fritz W Steuer, Bruce F Briglia, Michael K Purzycki, John R Scully, James M Fitz-Gerald
As a lightweight metal with mechanical properties similar to natural bone, Mg and its alloys are great prospects for biodegradable, load bearing implants. However, rapid degradation and H2 gas production in physiological media has prevented widespread use of Mg alloys. Surface heterogeneities in the form of intermetallic particles dominate the corrosion response. This research shows that surface homogenization significantly improved the biological corrosion response observed during immersion in simulated body fluid (SBF)...
May 11, 2017: Biointerphases
Garima Shukla, Diego Del Olmo Diaz, Vigneshwaran Thangavel, Alejandro A Franco
We report a comprehensive modeling-based study of electroactive suspensions in slurry redox flow batteries undergoing discharge. A three-dimensional kinetic Monte Carlo model based on the variable step size method is used to describe the electrochemical discharge of a silicon/carbon slurry electrode in static mode (i.e., no fluid flow conditions). The model accounts for Brownian motion of particles, volume expansion of silicon upon lithium insertion, and formation and destruction of conducting carbon networks...
May 19, 2017: ACS Applied Materials & Interfaces
Mahesh Ganesan, Michael J Solomon
We use direct current (DC) electric fields in conjunction with ultraviolet light to self-assemble highly dense structures of colloidal ellipsoids with three-dimensional order and volume fraction as large as 67%. Ellipsoidal phases of colloids are of fundamental interest because novel packing structures are predicted to occur at high volume fractions; the symmetries of these crystal unit cells can also contribute to a variety of applications, including structural color materials. Previously, the very high volume fraction range of ellipsoidal phases has been inaccessible because of limitations such as vitrification and kinetic trapping...
May 24, 2017: Soft Matter
Monica Moroni, Emanuela Lupo, Floriana La Marca
The separation of plastic wastes in mechanical recycling plants is the process that ensures high-quality secondary raw materials. An innovative device employing a wet technology for particle separation is presented in this work. Due to the combination of the characteristic flow pattern developing within the apparatus and density, shape and size differences among two or more polymers, it allows their separation into two products, one collected within the instrument and the other one expelled through its outlet ducts...
May 4, 2017: Waste Management
Jeffrey Comer, Klaus J Schulten, Christophe Chipot
Computational prediction of membrane permeability to small molecules requires accurate description of both the thermodynamics and kinetics underlying translocation across the lipid bilayer. In this contribution, well-converged, μs-long free-energy calculations are combined with a recently developed subdiffusive kinetics framework to describe the membrane permeation of a homologous series of short-tail alcohols, from methanol to 1-butanol, with unprecedented fidelity to the underlying molecular models. While the free-energy profiles exhibit barriers for passage through the center of the bilayer in all cases, the height of these barriers decreases with the length of the aliphatic chain of the alcohol, in quantitative agreement with experimentally determined differential solvation free energies in water and oil...
May 5, 2017: Journal of Chemical Theory and Computation
Huimin Zhou, Qiaoling Xiao, Wen Tan, Yiyi Zhan, Marco Pistolozzi
Several molecules containing carbamate groups are metabolized by cholinesterases. This metabolism includes a time-dependent catalytic step which temporary inhibits the enzymes. In this paper we demonstrate that the analysis of the area under the inhibition versus time curve (AUIC) can be used to obtain a quantitative estimation of the amount of carbamate metabolized by the enzyme. (R)-bambuterol monocarbamate and plasma butyrylcholinesterase were used as model carbamate-cholinesterase system. The inhibition of different concentrations of the enzyme was monitored for 5h upon incubation with different concentrations of carbamate and the resulting AUICs were analyzed...
April 9, 2017: Journal of Pharmaceutical and Biomedical Analysis
Constantine A Simintiras, Roger G Sturmey
The dietary derived isoflavone and oestrogen analogue, genistein, is known to perturb fundamental reproductive events such as implantation and embryo cleavage. However the question of whether genistein is able to traverse the oviduct epithelial monolayer and impact oviduct fluid secretion remains unclear. This study tests these research questions using a bioartificial oviduct to show that genistein permeates the oviduct lumen in vitro with a biphasic (burst and plateau) kinetic profile, faster than spontaneous diffusion, and alters the amino acid composition of in vitro derived oviduct fluid (ivDOF) but not as an oestrogen analogue...
April 28, 2017: Reproductive Toxicology
D R Hanson, I Bier, B Panta, C N Jen, P H McMurry
Computational fluid dynamics simulations of a flow reactor provided 3D spatial distributions of its temperature and flow profiles and abundances of sulfuric acid, nitrogeneous base, and the acid-base clusters formed from them. Clusters were simulated via their kinetic formation and decomposition involving sulfuric acid and base molecules. Temperature and flow profiles and the base and sulfuric acid distributions are characterized and the latter is compared to mass spectrometer measurements. Concentrations of simulated clusters of sulfuric acid with either NH3 or dimethylamine were compared to experimentally measured particle concentrations...
May 10, 2017: Journal of Physical Chemistry. A
Robert G Hahn
Excretion of crystalloid fluid is slow during general anesthesia. The distribution and elimination of buffered Ringer's solution were analyzed to determine whether the rate of elimination correlates with a hemodynamic factor, consciousness, patient posture, or the type of general anesthesia. Data were derived from 4 separately published studies in which 30 volunteers and 48 anesthetized patients had received 0.833 (1 series 0.667) mL/kg/min of lactated or acetated Ringer's solution over 30 minutes. Frequent measurements of the blood hemoglobin and mean urinary excretion were used as input in a kinetic analysis according to a 2-volume model and covariates, using microconstants and mixed-effects modeling software...
June 2017: Anesthesia and Analgesia
Zhen Zheng, Peiyao Chen, Gongyu Li, Yunxia Zhu, Zhonghua Shi, Yufeng Luo, Chun Zhao, Ziyi Fu, Xianwei Cui, Chenbo Ji, Fuqiang Wang, Guangming Huang, Gaolin Liang
CBT-Cys click condensation reaction has a high second-order reaction rate constant and has found wide applicability in recent years. However, its reaction mechanism has not been experimentally validated and its application for identifying bioactive N-terminal Cys peptides in real clinical samples has not been reported. Herein, firstly, by employing induced nanoelectrospray ionization-mass spectrometry (InESI-MS) and a home-built micro-reactor, we successfully intercepted and structurally characterized the crucial intermediate in this click reaction for the first time...
January 1, 2017: Chemical Science
Yangguang Ou, Stephen G Weber
Many sampling methods have been developed to measure the extracellular concentrations of solutes in the extracellular space of mammalian tissue, e.g., brain. However, few have been used to quantitatively study the various processes, such as enzymatic degradation, that determines the fate of these solutes. For a method to be useful in this pursuit, it must be able to (1) perfuse tissue and collect the perfusate for quantitative analysis of the solutes introduced and reaction products produced, (2) control the average residence time of the active solutes, and (3) have the appropriate spatial resolution for the process of interest...
May 11, 2017: Analytical Chemistry
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