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field flow fractionation

Isaac Ojea-Jiménez, Robin Capomaccio, Inês Osório, Dora Mehn, Giacomo Ceccone, Rohanah Hussain, Giuliano Siligardi, Pascal Colpo, François Rossi, Douglas Gilliland, Luigi Calzolai
Multi-functionalized nanoparticles are of great interest in biotechnology and biomedicine, especially for diagnostic and therapeutic purposes. However, at the moment the characterization of complex, multi-functional nanoparticles is still challenging and this hampers the development of advanced nanomaterials for biological applications. In this work, we have designed a model system consisting of gold nanoparticles functionalized with two differentially-terminated poly(ethylene oxide) ligands, providing both "stealth" properties and protein-binding capabilities to the nanoparticles...
May 22, 2018: Nanoscale
Jomy J Varghese, Isaac L Schmale, Mollie Eva Hansen, Shawn D Newlands, Danielle S W Benoit, Catherine E Ovitt
Hyposalivation is commonly observed in the autoimmune reaction of Sjögren's syndrome or following radiation injury to the major salivary glands. In these cases, questions remain regarding disease pathogenesis and effective interventions. An optimized technique that allows functional assessment of the salivary glands is invaluable for investigating exocrine gland biology, dysfunction, and therapeutics. Here, we present a step by step approach to performing pilocarpine stimulated saliva secretion, including tracheostomy and the dissection of the three major murine salivary glands...
May 4, 2018: Journal of Visualized Experiments: JoVE
M C Ortiz-Tafoya, Agnès Rolland-Sabaté, Catherine Garnier, Josefina Valadez-García, Alberto Tecante
Polysaccharide-surfactant blends are widely used in foods. However, their possible mutual interactions have not been extensively studied. The purpose of this work was to examine how the anionic surfactant sodium stearoyl lactylate (SSL) affects different properties of κ-carrageenan solutions and gels. Rheometry, differential scanning calorimetry, asymmetrical flow field-flow fractionation coupled with multiangle laser light scattering, among others, were used to determine the flow and viscoelastic behavior, thermal transitions, and conformation changes, respectively...
August 1, 2018: Carbohydrate Polymers
Markus Islinger, Robert Wildgruber, Alfred Völkl
Free-flow electrophoresis (FFE) exploits differences in the overall charge of bio-particles separating cells, organelles, macromolecules, ions etc. according to their distinct electrophoretic mobility and isoelectric point (pI) values. Indeed, around a neutral pH organelles usually exhibit a negative surface charge, migrating in an electric field from the cathode towards the anode. Since its introduction more than five decades ago by Barrollier et al. (1958) and Hannig (1961), FFE has become an established analytical and preparative separation method for the isolation of a variety of organelles...
May 15, 2018: Electrophoresis
Qiang Tang, Adrian L Collins, Anbang Wen, Xiubin He, Yuhai Bao, Dongchun Yan, Yi Long, Yusheng Zhang
The Three Gorges Dam has significantly interrupted fluvial continuity and modified the mass transfer regime along river continuums. Flow regulation following regular dam operations drives dramatic hydrological regime shifts, which facilitates sediment dispersal in the water-level fluctuation zone over episodic inundation periods. How flow regulation modulates sediment redistribution, however, remains unclear. In this study, we depict absolute particle size composition of suspended sediment and sink sediment in the water-level fluctuation zone, and these are interpreted in the context of flow regulation controls on sediment sorting...
August 15, 2018: Science of the Total Environment
Jianping Xu, Guancheng Jiang
Brine reaction and precipitation in porous media sometimes occur in the presence of a strong fluid flowing field, which induces the mobilization of the precipitated salts and distorts their spatial distribution. It is interesting to investigate how the distribution responds to such mobilization. We view these precipitates as random walkers in the complex inner space of the porous media, where they make stochastic jumps among locations and possibly wait between successive transitions. In consideration of related experimental results, the waiting time of the precipitates at a particular position is allowed to range widely from short sojourn to permanent residence...
April 2018: Physical Review. E
Ryan R Manning, Glenn A Wilson, Ryan E Holcomb, Nathaniel J Zbacnik, Auria A Tellechea, Chelsey L Gilley-Dunn, Ryan J Krammes, Nathan S Krammes, Gabriel J Evans, Charles S Henry, Mark Cornell Manning, Brian M Murphy, Robert W Payne, Derrick S Katayama
PURPOSE: To evaluate the different degrees of residual structure in the unfolded state of interferon-τ using chemical denaturation as a function of temperature by both urea and guanidinium hydrochloride. METHODS: Asymmetrical flow field-flow fractionation (AF4) using both UV and multi-angle laser light scattering (MALLS). Flow Microscopy. All subvisible particle imaging measurements were made using a FlowCAM flow imaging system. RESULTS: The two different denaturants provided different estimates of the conformational stability of the protein when extrapolated back to zero denaturant concentration...
May 9, 2018: Pharmaceutical Research
Kayeong Shin, Jaeyeong Choi, Yeoju Kim, Yoonjeong Lee, Joohoon Kim, Seungho Lee, Hoeil Chung
We propose a new analytical scheme in which field-flow fractionation (FFF)-based separation of target-specific polystyrene (PS) particle probes of different sizes are incorporated with amplified surface-enhanced Raman scattering (SERS) tagging for the simultaneous and sensitive detection of multiple microRNAs (miRNAs). For multiplexed detection, PS particles of three different diameters (15, 10, 5 μm) were used for the size-coding, and a probe single stranded DNA (ssDNA) complementary to a target miRNA was conjugated on an intended PS particle...
April 27, 2018: Journal of Chromatography. A
Alexander Patronis, Robin A Richardson, Sebastian Schmieschek, Brian J N Wylie, Rupert W Nash, Peter V Coveney
Drug targeting promises to substantially enhance future therapies, for example through the focussing of chemotherapeutic drugs at the site of a tumor, thus reducing the exposure of healthy tissue to unwanted damage. Promising work on the steering of medication in the human body employs magnetic fields acting on nanoparticles made of paramagnetic materials. We develop a computational tool to aid in the optimization of the physical parameters of these particles and the magnetic configuration, estimating the fraction of particles reaching a given target site in a large patient-specific vascular system for different physiological states (heart rate, cardiac output, etc...
2018: Frontiers in Physiology
Fabian Jan Schwarzendahl, Marco G Mazza
Suspensions of unicellular microswimmers such as flagellated bacteria or motile algae can exhibit spontaneous density heterogeneities at large enough concentrations. We introduce a novel model for biological microswimmers that creates the flow field of the corresponding microswimmers, and takes into account the shape anisotropy of the swimmer's body and stroke-averaged flagella. By employing multiparticle collision dynamics, we directly couple the swimmer's dynamics to the fluid's. We characterize the nonequilibrium phase diagram, as the filling fraction and Péclet number are varied, and find density heterogeneities in the distribution of both pullers and pushers, due to hydrodynamic instabilities...
May 2, 2018: Soft Matter
Björn Boll, Lena Josse, Anja Heubach, Sophie Hochenauer, Christof Finkler, Jörg Huwyler, Atanas V Koulov
Asymmetric flow field-flow fractionation is a valuable tool for the characterization of protein aggregates in biotechnology owing to its broad size range and unique separation principle. However, in practice asymmetric flow field-flow fractionation is non-trivial to use due to the major deviations from theory and the influence on separation by various factors that are not fully understood. Here we report methods to assess the non-ideal effects that influence asymmetric flow field-flow fractionation separation and for the first time identify experimentally the main factors that impact it...
April 25, 2018: Journal of Separation Science
Marie Lémery Magnin, Victor Fitoussi, Nathalie Siauve, Laetitia Pidial, Daniel Balvay, Gwennhael Autret, Charles André Cuenod, Olivier Clément, Laurent Julien Salomon
PURPOSE: To evaluate placental function and perfusion in a rat model of preeclampsia infused with L-nitro-arginine methyl ester (L-NAME) by dynamic contrast-enhanced (DCE) MRI using gadolinium chelates. METHODS: Pregnant female Sprague-Dawley rats were fitted on embryonic day 16 (E16) with subcutaneous osmotic minipumps loaded to deliver, continuously, L-NAME (50 mg/day per rat; case group) or saline solution (control group). DCE MRI was performed on E19 using gadolinium chelates and a 4...
April 24, 2018: Fetal Diagnosis and Therapy
Robert W Vanderpool, Jonathan D Krug, Surender Kaushik, Jerome Gilberry, Andrew Dart, Carlton L Witherspoon
Several low-volume inlets (flow rates ≤16.7 liters per minute (Lpm)) are commercially available as components of low-cost, portable ambient particulate matter samplers. Because the inlets themselves do not contain internal fractionators, they are often assumed to representatively sample "total" mass concentrations from the ambient air, independent of aerodynamic particle size and wind speed. To date, none of these so-called "TSP" inlets have been rigorously tested under controlled conditions...
2018: Aerosol Science and Technology: the Journal of the American Association for Aerosol Research
S J Payne, W K El-Bouri
The cerebral microvasculature plays a key role in the transport of blood and the delivery of nutrients to the cells that perform brain function. Although recent advances in experimental imaging techniques mean that its structure and function can be interrogated to very small length scales, allowing individual vessels to be mapped to a fraction of 1 μm, these techniques currently remain confined to animal models. In-vivo human data can only be obtained at a much coarser length scale, of order 1 mm, meaning that mathematical models of the microvasculature play a key role in interpreting flow and metabolism data...
April 19, 2018: NeuroImage
Faris Durmo, Jimmy Lätt, Anna Rydelius, Silke Engelholm, Sara Kinhult, Krister Askaner, Elisabet Englund, Johan Bengzon, Markus Nilsson, Isabella M Björkman-Burtscher, Thomas Chenevert, Linda Knutsson, Pia C Sundgren
The aim was to evaluate volume, diffusion, and perfusion metrics for better presurgical differentiation between high-grade gliomas (HGG), low-grade gliomas (LGG), and metastases (MET). For this retrospective study, 43 patients with histologically verified intracranial HGG (n = 18), LGG (n = 10), and MET (n = 15) were chosen. Preoperative magnetic resonance data included pre- and post-gadolinium contrast-enhanced T1-weighted fluid-attenuated inversion recover, cerebral blood flow (CBF), cerebral blood volume (CBV), fractional anisotropy, and apparent diffusion coefficient maps used for quantification of magnetic resonance biometrics by manual delineation of regions of interest...
March 2018: Tomography: a Journal for Imaging Research
Catalina Fuentes, Joel Castillo, Jose Vila, Lars Nilsson
The use of polymers for the delivery of drugs has increased dramatically in the last decade. To ensure the desired properties and functionality of such substances, adequate characterization in terms of the molar mass (M) and size is essential. The aim of this study was to evaluate the changes in the M and size of PVP-b-PAMPS when the amounts of the synthesis reactants in the two-step radical reaction were varied. The determination of the M and size distributions was performed by an asymmetric flow field-flow fractionation (AF4) system connected to multiangle light scattering (MALS) and differential refractive index (dRI) detectors...
April 16, 2018: Analytical and Bioanalytical Chemistry
Miguel Ángel Lominchar, María José Sierra, María Jiménez-Moreno, María Guirado, Rosa Carmen Rodríguez Martín-Doimeadios, Rocío Millán
Monomethylmercury (MeHg) is one of the most toxic and the most commonly occurring organomercury compound and the wetlands are one of the main areas of generation of this Hg form. Concretely, it is in the macrophyte root system where better conditions are given for its generation. However, the knowledge of absorption and subsequent distribution of mercury (Hg) and monomethylmercury in aquatic plants is still limited. Mercury mining district such as Almadén (Ciudad Real, Spain) is a natural laboratory where different rivers flow and the species Typha domingensis Pers...
April 11, 2018: Environmental Science and Pollution Research International
Anna Missong, Stefan Holzmann, Roland Bol, Volker Nischwitz, Heike Puhlmann, Klaus V Wilpert, Jan Siemens, Erwin Klumpp
The leaching of P from the upper 20cm of forest topsoils influences nutrient (re-)cycling and the redistribution of available phosphate and organic P forms. However, the effective leaching of colloids and associated P forms from forest topsoils was so far sparsely investigated. We demonstrated through irrigation experiments with undisturbed mesocosm soil columns, that significant proportions of P leached from acidic forest topsoils were associated with natural colloids. These colloids had a maximum size of 400nm...
April 5, 2018: Science of the Total Environment
Viorica Railean-Plugaru, Pawel Pomastowski, Tomasz Kowalkowski, Myroslav Sprynskyy, Boguslaw Buszewski
Asymmetric flow field-flow fractionation coupled with use of ultraviolet-visible, multiangle light scattering (MALLS), and dynamic light scattering (DLS) detectors was used for separation and characterization of biologically synthesized silver composites in two liquid compositions. Moreover, to supplement the DLS/MALLS information, various complementary techniques such as transmission electron spectroscopy, Fourier transform infrared spectroscopy, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used...
April 3, 2018: Analytical and Bioanalytical Chemistry
Amelia Geraldine Peregrina-Chávez, María Del Rayo Ramírez-Galindo, Rolando Chávez-Martínez, Cesar Anuar Delahanty-Delgado, Fernando Vazquez-Alaniz
Background: The biological behaviour and clinical significance of mercury toxicity vary according to its chemical structure. Mercury differs in its degree of toxicity and in its effects on the nervous, digestive and immune systems as well as on organs such as the lungs, kidneys, skin, eyes and heart. Human exposure occurs mainly through inhalation of elemental mercury vapours during industrial and artisanal processes such as artisanal and small-scale gold mining. Case presentation: A 52-years-old female, housewife, with a body mass index of 25...
April 2, 2018: International Journal of Environmental Research and Public Health
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