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field flow fractionation

Apostolos Kiaos, Ioannis Tziatzios, Stavros Hadjimiltiades, Charalambos Karvounis, Theodoros D Karamitsos
Stress perfusion cardiac magnetic resonance (CMR) has been proposed as an important gatekeeper for invasive coronary angiography (ICA) and percutaneous coronary interventions (PCI) in patients evaluated for possible coronary artery disease (CAD) (Fihn et al., 2012; Montalescot et al., 2013) [1], [2]. Several meta-analyses have evaluated the accuracy of stress perfusion CMR to diagnose CAD at the vessel level (Danad et al., 2017; Dai et al., 2016; Jiang et al., 2016; Takx et al., 2015; Li et al., 2015; Desai and Jha, 2013; Jaarsma et al...
February 2018: Data in Brief
Lurong Yang, Xinyu Wang, Itza Mendoza-Sanchez, Linda M Abriola
Sequestered mass in low permeability zones has been increasingly recognized as an important source of organic chemical contamination that acts to sustain downgradient plume concentrations above regulated levels. However, few modeling studies have investigated the influence of this sequestered mass and associated (coupled) mass transfer processes on plume persistence in complex dense nonaqueous phase liquid (DNAPL) source zones. This paper employs a multiphase flow and transport simulator (a modified version of the modular transport simulator MT3DMS) to explore the two- and three-dimensional evolution of source zone mass distribution and near-source plume persistence for two ensembles of highly heterogeneous DNAPL source zone realizations...
March 8, 2018: Journal of Contaminant Hydrology
Melanie E Fields, Kristin P Guilliams, Dustin K Ragan, Michael M Binkley, Cihat Eldeniz, Yasheng Chen, Monica L Hulbert, Robert C McKinstry, Joshua S Shimony, Katie D Vo, Allan Doctor, Hongyu An, Andria L Ford, Jin-Moo Lee
OBJECTIVE: To determine mechanisms underlying regional vulnerability to infarction in sickle cell disease (SCD) by measuring voxel-wise cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen utilization (CMRO2 ) in children with SCD. METHODS: Participants underwent brain MRIs to measure voxel-based CBF, OEF, and CMRO2 . An infarct heat map was created from an independent pediatric SCD cohort with silent infarcts and compared to prospectively obtained OEF maps...
March 2, 2018: Neurology
Beatrice Bocca, Stefano Caimi, Oreste Senofonte, Alessandro Alimonti, Francesco Petrucci
This study sought to develop analytical methods to characterize titanium dioxide (TiO2 ) and zinc oxide (ZnO) nanoparticles (NPs), including the particle size distribution and concentration, in cream and spray sunscreens with different sun protection factor (SPF). The Single Particle Inductively Coupled Plasma-Mass Spectrometry (SP ICP-MS) was used as screening and fast method to determine particles size and number. The Asymmetric Flow-Field Flow Fractionation (AF4-FFF) as a pre-separation technique was on-line coupled to the Multi-Angle Light Scattering (MALS) and ICP-MS to determine particle size distributions and size dependent multi-elemental concentration...
February 27, 2018: Science of the Total Environment
Lee R Moore, Daichi Mizutani, Tomoya Tanaka, Amy Buck, Mark Yazer, Maciej Zborowski, Jeffrey J Chalmers
The ability to separate RBCs from the other components of whole blood has a number of useful clinical and research applications ranging from removing RBCs from typical clinical blood draw, bone marrow transplants to transfusions of these RBCs to patients after significant blood loss. Viewed from a mechanistic/process perspective, there are three routine methodologies to remove RBCs: 1) RBCs lysis, 2) separation of the RBCs from the nucleated cells (i.e., stem cells) based on density differences typically facilitated through centrifugation or sedimentation agents, and 3) antibody based separation in which a targeted RBC is bound with an affinity ligand that facilitates its removal...
February 24, 2018: Biotechnology and Bioengineering
Lindsay A McMillan, Michael O Rivett, Gary P Wealthall, Peter Zeeb, Peter Dumble
Groundwater-quality assessment at contaminated sites often involves the use of short-screen (1.5 to 3 m) monitoring wells. However, even over these intervals considerable variation may occur in contaminant concentrations in groundwater adjacent to the well screen. This is especially true in heterogeneous dense non-aqueous phase liquid (DNAPL) source zones, where cm-scale contamination variability may call into question the effectiveness of monitoring wells to deliver representative data. The utility of monitoring wells in such settings is evaluated by reference to high-resolution multilevel sampler (MLS) wells located proximally to short-screen wells, together with sampling capture-zone modelling to explore controls upon well sample provenance and sensitivity to monitoring protocols...
February 9, 2018: Journal of Contaminant Hydrology
Huacheng Xu, Laodong Guo
Dissolved organic matter (DOM) is ubiquitous and plays an important role in regulating water quality, ecological function, and the fate and transport of trace elements and pollutants in aquatic environments. Both the colloidal precursors (i.e. <1 kDa) and bulk DOM collected from a freshwater estuary were incubated in the dark for 21 days to examine dynamic changes in molecular size and composition induced by microbial degradation and self-assembly. Results showed that the concentrations of total organic carbon, carbohydrates, and protein-like substances decreased by 11-30% during incubation, while those of humic- and fulvic-like substances remained relatively constant, indicating humic substances are more resistant to microbial utilization compared to carbohydrates and protein-like DOM...
February 7, 2018: Water Research
Haiying Zhang, Daniela Freitas, Han Sang Kim, Kristina Fabijanic, Zhong Li, Haiyan Chen, Milica Tesic Mark, Henrik Molina, Alberto Benito Martin, Linda Bojmar, Justin Fang, Sham Rampersaud, Ayuko Hoshino, Irina Matei, Candia M Kenific, Miho Nakajima, Anders Peter Mutvei, Pasquale Sansone, Weston Buehring, Huajuan Wang, Juan Pablo Jimenez, Leona Cohen-Gould, Navid Paknejad, Matthew Brendel, Katia Manova-Todorova, Ana Magalhães, José Alexandre Ferreira, Hugo Osório, André M Silva, Ashish Massey, Juan R Cubillos-Ruiz, Giuseppe Galletti, Paraskevi Giannakakou, Ana Maria Cuervo, John Blenis, Robert Schwartz, Mary Sue Brady, Héctor Peinado, Jacqueline Bromberg, Hiroshi Matsui, Celso A Reis, David Lyden
The heterogeneity of exosomal populations has hindered our understanding of their biogenesis, molecular composition, biodistribution and functions. By employing asymmetric flow field-flow fractionation (AF4), we identified two exosome subpopulations (large exosome vesicles, Exo-L, 90-120 nm; small exosome vesicles, Exo-S, 60-80 nm) and discovered an abundant population of non-membranous nanoparticles termed 'exomeres' (~35 nm). Exomere proteomic profiling revealed an enrichment in metabolic enzymes and hypoxia, microtubule and coagulation proteins as well as specific pathways, such as glycolysis and mTOR signalling...
March 2018: Nature Cell Biology
Joanna Makselon, Nina Siebers, Florian Meier, Harry Vereecken, Erwin Klumpp
Undisturbed outdoor lysimeters containing arable loamy sand soil were used to examine the influence of either heavy rain events (high frequency of high rain intensity), steady rain (continuous rainfall of low rain intensity), and natural rainfall on the transport and retention of surfactant-stabilized silver nanoparticles (AgNP). In addition, the AgNP-soil associations within the A p horizon were analyzed by means of particle-size fractionation, asymmetrical flow field-flow fractionation coupled with UV/Vis-detection and inductively coupled plasma mass spectrometer (AF4-UV/Vis-ICP-MS), and transmission electron microscopy coupled to an energy-dispersive X-ray (TEM-EDX) analyzer...
February 12, 2018: Environmental Pollution
Marion E Fraunhofer, Frank Jakob, Rudi F Vogel
We wanted to identify key factors influencing the extent of β-glucan production by Lactobacillus brevis TMW 1.2112, which has been isolated from viscous, spoiled beer and which could contribute to viscosity increases of spoiled beverages via exopolysaccharide (EPS) production. In this way, we analyzed the influence of different initial pH values and carbohydrate sources on growth of and slime/β-glucan formation by this strain. In a screening of 48 carbohydrates, 14 fermentable sugars which enabled growth were identified...
February 13, 2018: Current Microbiology
Andrew J Chetwynd, Emily J Guggenheim, Sophie M Briffa, James A Thorn, Iseult Lynch, Eugenia Valsami-Jones
Due to the increasing use and production of nanomaterials (NMs), the ability to characterise their physical/chemical properties quickly and reliably has never been so important. Proper characterisation allows a thorough understanding of the material and its stability, and is critical to establishing dose-response curves to ascertain risks to human and environmental health. Traditionally, methods such as Transmission Electron Microscopy (TEM), Field Flow Fractionation (FFF) and Dynamic Light Scattering (DLS) have been favoured for size characterisation, due to their wide-availability and well-established protocols...
February 10, 2018: Nanomaterials
Jochen Bandelin, Thomas Lippert, Jörg E Drewes, Konrad Koch
The generation of cavitation fields for the pre-treatment of anaerobic sludge was studied by means of a novel acoustic measuring system. The influence of different reactor dimensions (i.e., choosing reaction chamber widths of 40, 60 and 80 mm) on the cavitation intensity was determined at various solid contents, flow rates and static pressures. Results suggest that the cavitation intensity is significantly reduced by the sonication of liquids with a high solid content. By increasing the pressure to 1 bar, the intensity of bubble implosions can be enhanced and the sound attenuation in the solid fraction is partly compensated compared to ambient pressure...
April 2018: Ultrasonics Sonochemistry
David Müller, Margarida Nogueira, Stefano Cattaneo, Florian Meier, Roland Drexel, Catia Contado, Antonella Pagnoni, Tjerk de Vries, Dror Cohen, Meital Portugal-Cohen, Andrew J deMello
We report the use of inverse Supercritical Fluid Extraction (inverse SFE) and miniaturized Asymmetrical Flow Field-Flow Fractionation (mAF4) for the preparation and subsequent analysis of titanium dioxide nanoparticles in model and commercial sunscreens. The approach allows for the fast and reliable fractionation and sizing of TiO2-nanoparticles and their quantitation in commercial products. This new method represents a powerful and efficient tool for the verification of nanoparticle-content in a wide range of matrices, as demanded by recently introduced regu-latory requirements...
February 7, 2018: Analytical Chemistry
Manuel Correia, Katrin Loeschner
We tested the suitability of asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) for detection of nanoplastics in fish. A homogenized fish sample was spiked with 100 nm polystyrene nanoparticles (PSNPs) (1.3 mg/g fish). Two sample preparation strategies were tested: acid digestion and enzymatic digestion with proteinase K. Both procedures were found suitable for degradation of the organic matrix. However, acid digestion resulted in large PSNPs aggregates/agglomerates (> 1 μm)...
February 6, 2018: Analytical and Bioanalytical Chemistry
Emel Kaya Aumann, Sadik Server, Bedriye Koyuncu Sokmen, Aysegul Oz, Esat Namal, Nagihan Inan Gurcan, Numan Cem Balci, Yaman Tokat
PURPOSE: To evaluate the diagnostic accuracy of intravoxel incoherent motion (IVIM) and diffusion-weighted imaging (DWI) parameters in the differential diagnosis of portal vein thrombus (PVT). METHODOLOGY: Thirty-five patients with PVT were enrolled in this retrospective study. Precontrast axial in-phase and out-of-phase T1-weighted (W) turbo field echo (TFE), axial and coronal T2-W single-shot turbo spin echo, IVIM with b values between 0 and 1300 s/mm2 and conventional DWI with b factors of 50, 400, and 800 s/mm2 with single-shot echo-planar imaging, and postcontrast dynamic T1-W volumetric interpolated breath-hold examination images obtained with 1...
February 7, 2018: Abdominal Radiology
Valentina Marassi, Luisana Di Cristo, Stephen G J Smith, Simona Ortelli, Magda Blosi, Anna L Costa, Pierluigi Reschiglian, Yuri Volkov, Adriele Prina-Mello
Silver nanoparticle-based antimicrobials can promote a long lasting bactericidal effect without detrimental toxic side effects. However, there is not a clear and complete protocol to define and relate the properties of the particles (size, shape, surface charge, ionic content) with their specific activity. In this paper, we propose an effective multi-step approach for the identification of a 'purpose-specific active applicability window' to maximize the antimicrobial activity of medical devices containing silver nanoparticles (Ag NPs) (such as surface coaters), minimizing any consequent risk for human health (safety by design strategy)...
January 2018: Royal Society Open Science
Filippo Bianchi, Marcel Thielmann, Lucilla de Arcangelis, Hans Jürgen Herrmann
Particle detachment bursts during the flow of suspensions through porous media are a phenomenon that can severely affect the efficiency of deep bed filters. Despite the relevance in several industrial fields, little is known about the statistical properties and the temporal organization of these events. We present experiments of suspensions of deionized water carrying quartz particles pushed with a peristaltic pump through a filter of glass beads measuring simultaneously the pressure drop, flux, and suspension solid fraction...
January 19, 2018: Physical Review Letters
Soheyl Tadjiki, Ronald Beckett
The commonly used theory to describe the normal Brownian mode of field-flow fractionation (FFF) assumes the particles to be point masses and hence the shape is ignored. Beckett and Giddings extended this theory to include the effect of thin rods and discs being forced very close to the accumulation wall. By including the decrease in the entropy this causes, they derived new expressions for the retention of such nonspherical particles in FFF. The steric-entropic theory predicts that when the sample cloud thickness is less than the major dimension of the rods or discs then particles elute earlier than predicted by the Brownian mode theory...
February 2, 2018: Journal of Chromatography. A
Christoph Neukum
Silver nanoparticles (Ag-NP) are used in various consumer products and are one of the most prevalent metallic nanoparticle in commodities and are released into the environment. Transport behavior of Ag-NP in groundwater is one important aspect for the assessment of environmental impact and protection of drinking water resources in particular. Ag-NP transport processes in saturated single-fractured sandstones using triaxial flow cell experiments with different kind of sandstones is investigated. Ag-NP concentration and size are analyzed using flow field-flow fractionation and coupled SEM-EDX analysis...
January 30, 2018: Journal of Contaminant Hydrology
James L Harden, Hongyu Guo, Martine Bertrand, Tyler N Shendruk, Subramanian Ramakrishnan, Robert L Leheny
Colloidal suspensions transform between fluid and disordered solid states as parameters such as the colloid volume fraction and the strength and nature of the colloidal interactions are varied. Seemingly subtle changes in the characteristics of the colloids can markedly alter the mechanical rigidity and flow behavior of these soft composite materials. This sensitivity creates both a scientific challenge and an opportunity for designing suspensions for specific applications. In this paper, we report a novel mechanism of gel formation in mixtures of weakly attractive nanocolloids with modest size ratio...
January 28, 2018: Journal of Chemical Physics
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