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field flow fractionation

S Dutz, M E Hayden, U O Häfeli
Magnetic forces and curvature-induced hydrodynamic drag have both been studied and employed in continuous microfluidic particle separation and enrichment schemes. Here we combine the two. We investigate consequences of applying an outwardly directed magnetic force to a dilute suspension of magnetic microspheres circulating in a spiral microfluidic channel. This force is realized with an array of permanent magnets arranged to produce a magnetic field with octupolar symmetry about the spiral axis. At low flow rates particles cluster around an apparent streamline of the flow near the outer wall of the turn...
2017: PloS One
Pierre-Antoine Faye, Olivier Roualdes, Fabrice Rossignol, Daniel Jean Hartmann, Alexis Desmoulière
Despite many studies, the impact of ceramic particles on cell behavior remains still unclear. The aim of the present study was to investigate the effects of ceramic nano-sized particles on fibroblastic cells. Fibroblasts (dermal fibroblasts freshly isolated from skin samples and WI26 fibroblastic cells) were cultured in monolayer in the presence of alumina or cerium-zirconia particles (��� 50 nm diameter) at two concentrations (100 or 500 ��g.mL-1). Fluorescent alumina particles were also used. Cell morphology, cytoplasmic ceramic incorporation using confocal and transmission electron microscopy, and migration using silicon insert, were analyzed...
January 19, 2017: Biomedical Materials
Eugenio Picano, Quirino Ciampi, Rodolfo Citro, Antonello D'Andrea, Maria Chiara Scali, Lauro Cortigiani, Iacopo Olivotto, Fabio Mori, Maurizio Galderisi, Marco Fabio Costantino, Lorenza Pratali, Giovanni Di Salvo, Eduardo Bossone, Francesco Ferrara, Luna Gargani, Fausto Rigo, Nicola Gaibazzi, Giuseppe Limongelli, Giuseppe Pacileo, Maria Grazia Andreassi, Bruno Pinamonti, Laura Massa, Marco A R Torres, Marcelo H Miglioranza, Clarissa Borguezan Daros, José Luis de Castro E Silva Pretto, Branko Beleslin, Ana Djordjevic-Dikic, Albert Varga, Attila Palinkas, Gergely Agoston, Dario Gregori, Paolo Trambaiolo, Sergio Severino, Ayana Arystan, Marco Paterni, Clara Carpeggiani, Paolo Colonna
BACKGROUND: Stress echocardiography (SE) has an established role in evidence-based guidelines, but recently its breadth and variety of applications have extended well beyond coronary artery disease (CAD). We lack a prospective research study of SE applications, in and beyond CAD, also considering a variety of signs in addition to regional wall motion abnormalities. METHODS: In a prospective, multicenter, international, observational study design, > 100 certified high-volume SE labs (initially from Italy, Brazil, Hungary, and Serbia) will be networked with an organized system of clinical, laboratory and imaging data collection at the time of physical or pharmacological SE, with structured follow-up information...
January 18, 2017: Cardiovascular Ultrasound
Thilak K Mudalige, Haiou Qu, Sean W Linder
Asymmetric flow field flow fractionation (AF4) is an efficient size based separation technique for the characterization of submicron size particulates. In AF4, membranes having various molecular weight cut-off sizes are used as a barrier to retain particles while allowing carrier fluid containing electrolytes to permeate. Here, we hypothesized that electrolyte rejection by the barrier membrane lead to the accumulation of the electrolytes in the channel during operation. Electrolyte accumulation can cause various adverse effects which can lead to membrane fouling...
January 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Alejandra Castro, Francisco Vilaplana, Lars Nilsson
Yacon (Smallanthus sonchifolius Poepp. & Endl.) roots are largely grown in Andean countries and have attracted recent interest due to their antioxidant and prebiotic effects. Yacon is typically consumed as a fruit due to its sweet taste and juiciness. The macromolecular properties of an aqueous extract of yacon are investigated using asymmetric flow field-flow fractionation (AF4) coupled to UV, multiangle light scattering (MALS) and differential refractive index (dRI) detection. The method allows for determination of molar mass and size over the size distribution...
May 15, 2017: Food Chemistry
Pooja Bansal, Abhijit P Deshpande, Madivala G Basavaraj
Hetero-aggregation refers to aggregation of particles that are not identical i.e. particles of different physical-chemical properties. The investigation of this phenomenon is important because of the fascinating structures that can be formed and their application in several fields including the synthesis of porous materials and particle stabilized emulsions. We report an experimental study of hetero-aggregation behaviour of oppositely charged nanoparticles of similar size. In this study, the hetero-aggregation phenomenon is investigated using a combination of visual observation, zeta potential measurements, dynamic light scattering, scanning electron microscopy and rheology measurements...
December 28, 2016: Journal of Colloid and Interface Science
S Lee, A Rimner, S Hayes, M Hunt, J Deasy, M Zauderer, V Rusch, N Tyagi
PURPOSE: To use dual-input tracer kinetic modeling of the lung for mapping spatial heterogeneity of various kinetic parameters in malignant MPM METHODS: Six MPM patients received DCE-MRI as part of their radiation therapy simulation scan. 5 patients had the epitheloid subtype of MPM, while one was biphasic. A 3D fast-field echo sequence with TR/TE/Flip angle of 3.62ms/1.69ms/15° was used for DCE-MRI acquisition. The scan was collected for 5 minutes with a temporal resolution of 5ߝ9 seconds depending on the spatial extent of the tumor...
June 2016: Medical Physics
F Hamza, A Abd El-Latief, W Khatan
In this work, the fractional mathematical model of an unsteady rotational flow of Xanthan gum (XG) between two cylinders in the presence of a transverse magnetic field has been studied. This model consists of two fractional parameters α and β representing thermomechanical effects. The Laplace transform is used to obtain the numerical solutions. The fractional parameter influence has been discussed graphically for the functions field distribution (temperature, velocity, stress and electric current distributions)...
2017: PloS One
Guozhi Xu, Wei Hong, Weixiang Sun, Tao Wang, Zhen Tong
The motions of the particles on the substrate of a drying sessile colloidal droplet of water were measured using multiparticle tracking. Droplets with different concentrations (0-250 mM) of sodium chloride (NaCl) were compared. Several statistical quantities were proposed to characterize the heterogeneous behaviors of the particles and distinguish the effects of the flow field and the substrate interaction. For the salt-free droplet, most of the particles were nonadsorbed and mobile without friction. With the presence of salt, the fraction of the adsorbed particles increases with increasing evaporation time and the initial salt concentration, which was explained by Derjaguin-Landau-Verwey-Overbeek interaction...
January 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
G Rigaux, C V Gheran, M Callewaert, C Cadiou, S N Voicu, A Dinischiotu, M C Andry, L Vander Elst, S Laurent, R N Muller, A Berquand, M Molinari, S Huclier-Markai, F Chuburu
Chitosan CS-tripolyphosphate TPP/hyaluronic acid HA nanohydrogels loaded with gadolinium chelates (GdDOTA ⊂ CS-TPP/HA NGs) synthesized by ionic gelation were designed for lymph node (LN) MRI. In order to be efficiently drained to LNs, nanogels (NGs) needed to exhibit a diameter ϕ < 100 nm. For that, formulation parameters were tuned, using (i) CS of two different molecular weights (51 and 37 kDa) and (ii) variable CS/TPP ratio (2 < CS/TPP < 8). Characterization of NG size distribution by dynamic light scattering (DLS) and asymetrical flow-field-flow-fractionation (AF4) showed discrepancies since DLS diameters were consistently above 200 nm while AF4 showed individual nano-objects with ϕ < 100 nm...
February 3, 2017: Nanotechnology
Ugo Till, Mireille Gaucher, Baptiste Amouroux, Stéphane Gineste, Barbara Lonetti, Jean-Daniel Marty, Christophe Mingotaud, Carmen R M Bria, S Kim Ratanathanawongs Williams, Frédéric Violleau, Anne-Françoise Mingotaud
Polymer self-assemblies joining oppositely charged chains, known as polyion complexes (PICs), have been formed using poly(ethyleneoxide - b - acrylic acid)/poly(l-lysine), poly(ethyleneoxide-b-acrylic acid)/dendrigraft poly(l-lysine) and poly[(3-acrylamidopropyl) trimethylammonium chloride - b - N - isopropyl acrylamide]/poly(acrylic acid). The self-assemblies have been first characterized in batch by Dynamic Light Scattering. In a second step, their analysis by Flow Field-Flow Fractionation techniques (FlFFF) was examined...
December 19, 2016: Journal of Chromatography. A
Kathryn J Tindale, Pritesh J Patel, Dirk Wallschläger
Asymmetric flow-field flow fractionation-inductively-coupled plasma-mass spectrometry was used to determine whether colloidal arsenic (As) exists in soil pore water and soil extract samples at two arsenic-contaminated abandoned gold mines (Montague and Goldenville, Nova Scotia). Colloidal arsenic was found in 12 out of the 80 collected samples (=15%), and was primarily associated with iron (Fe) in the encountered colloids. The molar Fe/As ratios indicate that the colloids in some samples appeared to be discrete iron-arsenic minerals, whereas in other samples, they were more consistent with As-rich iron (oxy)hydroxides...
November 2016: Journal of Environmental Sciences (China)
Shinichi Sakamoto, Hidetoshi Ikeda, Naohiro Tsuyuguchi, Takehiro Uda, Eiichi Okumura, Takashi Asakawa, Yasuhiro Haruta, Hideki Nishiyama, Toyoji Okada, Hajime Kamada, Kenji Ohata, Yukio Miki
PURPOSE: Quantitative imaging of neuromagnetic fields based on automated region of interest (ROI) setting was analyzed to determine the characteristics of cerebral neural activity in ischemic areas. METHODS: Magnetoencephalography (MEG) was used to evaluate spontaneous neuromagnetic fields in the ischemic areas of 37 patients with unilateral internal carotid artery (ICA) occlusive disease. Voxel-based time-averaged intensity of slow waves was obtained in two frequency bands (0...
2016: PloS One
Claudia Zielke, Cristina Teixeira, Huihuang Ding, Steve Cui, Margareta Nyman, Lars Nilsson
β-Glucan benefits are related with its molar mass and it would be of interest to better understand how this parameter can be changed by processing and variety for design of food with specific health effects. For this purpose, extracts from barley malts and brewers' spent grain, processed at different conditions, were analysed regarding β-glucan content, molar mass, and protein content. Molar mass distribution was assessed using asymmetric flow field-flow fractionation (AF4) with multiangle light scattering (MALS), differential refractive index (dRI) and fluorescence (FL) detection...
February 10, 2017: Carbohydrate Polymers
Diana C António, Claudia Cascio, Douglas Gilliland, António J A Nogueira, François Rossi, Luigi Calzolai
The detection and quantification of nanoparticles is a complex issue due to the need to combine "classical" identification and quantification of the constituent material, with the accurate determination of the size of submicrometer objects, usually well below the optical diffraction limit. In this work, the authors show that one of the most used analytical methods for silver nanoparticles, asymmetric flow field-flow fractionation, can be strongly influenced by the presence of dissolved organic matter (such as alginate) and lead to potentially misleading results...
December 16, 2016: Biointerphases
Petra Krupičková, Michal Huptych, Zuzana Mormanová, Tomáš Bouček, Tomáš Belza, Ondřej Šmíd, Aleš Král, Hana Skalická, Aleš Linhart, Jan Bělohlávek
The effect of pulsatile blood flow on microcirculation during extracorporeal cardiopulmonary resuscitation (ECPR) is not elucidated, therefore we designed an observational study comparing sublingual microcirculation in refractory cardiac arrest patients with spontaneously pulsatile or low/non-pulsatile blood flow following treatment with ECPR. Microcirculation was assessed with Sidestream Dark Field technology in 12 cardiac arrest patients treated with ECPR and 12 healthy controls. Microcirculatory images were analyzed offline in a blinded fashion and consensual parameters were determined for the vessels ≤ 20 μm...
December 13, 2016: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
Paul Vernon Jones, Gabriel L Salmon, Alexandra Ros
Separation of nucleic acids has long served as a central goal of analytical research. Innovations in this field may soon enable the development of rapid, on-site sequencing devices that significantly improve both the availability and accuracy of detailed bioinformatics. However, achieving efficient continuous-flow operation and size-based fractionation of DNA still presents considerable challenges. Current methods have not yet satisfied the need for rapid fractionation of size-heterogeneous nucleic acid samples into specific and narrow size distributions...
December 12, 2016: Analytical Chemistry
M F Campbell, G A Bohlin, P E Schrader, R P Bambha, C J Kliewer, K O Johansson, H A Michelsen
We have designed and constructed a Hencken-type burner that produces a 38-mm-long linear laminar partially premixed co-flow diffusion flame. This burner was designed to produce a linear flame for studies of soot chemistry, combining the benefit of the conventional Hencken burner's laminar flames with the advantage of the slot burner's geometry for optical measurements requiring a long interaction distance. It is suitable for measurements using optical imaging diagnostics, line-of-sight optical techniques, or off-axis optical-scattering methods requiring either a long or short path length through the flame...
November 2016: Review of Scientific Instruments
Irina V Safenkova, Elvira S Slutskaya, Vasily G Panferov, Anatoly V Zherdev, Boris B Dzantiev
Conjugates of gold nanoparticles (GNPs) with antibodies are powerful analytical tools. It is crucial to know the conjugates' state in both the concentrated and mixed solutions used in analytical systems. Herein, we have applied asymmetrical flow field-flow fractionation (AF4) to identify the conjugates' state. The influence of a conjugate's composition and concentration on aggregation was studied in a true analytical solution (a concentrated mixture with stabilizing components). GNPs with an average diameter of 15...
December 16, 2016: Journal of Chromatography. A
A M Bavo, A M Pouch, J Degroote, J Vierendeels, J H Gorman, R C Gorman, P Segers
BACKGROUND: As the intracardiac flow field is affected by changes in shape and motility of the heart, intraventricular flow features can provide diagnostic indications. Ventricular flow patterns differ depending on the cardiac condition and the exploration of different clinical cases can provide insights into how flow fields alter in different pathologies. METHODS: In this study, we applied a patient-specific computational fluid dynamics model of the left ventricle and mitral valve, with prescribed moving boundaries based on transesophageal ultrasound images for three cardiac pathologies, to verify the abnormal flow patterns in impaired hearts...
January 4, 2017: Journal of Biomechanics
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