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field flow fractionation

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...
November 22, 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...
November 11, 2016: Journal of Biomechanics
Kenneth Flack, Luis A Jimenez, Wenwan Zhong
MicroRNAs (miRNAs) are stably present in circulatory systems. They are bound to various carriers like proteins, lipoprotein particles, and exosomes. Investigating the process of miRNA distribution among these carriers will help improve our understanding of their functions in the extracellular environment and their potential relationship with diseases. Here, we describe how to obtain the distribution profiles of circulating miRNAs by separation of different miRNA carriers in human serum with asymmetrical flow field flow fractionation (AF4), and detection of the miRNAs in the eluted fractions that enrich particular types of carriers with RT-qPCR...
2017: Methods in Molecular Biology
Mohamad Reza Soltanian, Mohammad Amin Amooie, Zhenxue Dai, David Cole, Joachim Moortgat
When CO2 is injected in saline aquifers, dissolution causes a local increase in brine density that can cause Rayleigh-Taylor-type gravitational instabilities. Depending on the Rayleigh number, density-driven flow may mix dissolved CO2 throughout the aquifer at fast advective time-scales through convective mixing. Heterogeneity can impact density-driven flow to different degrees. Zones with low effective vertical permeability may suppress fingering and reduce vertical spreading, while potentially increasing transverse mixing...
November 3, 2016: Scientific Reports
Anne A Galyean, James J Filliben, R David Holbrook, Wyatt N Vreeland, Howard S Weinberg
Asymmetric flow field flow fractionation (AF(4)) has several instrumental factors that may have a direct effect on separation performance. A sensitivity analysis was applied to ascertain the relative importance of AF(4) primary instrument factor settings for the separation of a complex environmental sample. The analysis evaluated the impact of instrumental factors namely, cross flow, ramp time, focus flow, injection volume, and run buffer concentration on the multi-angle light scattering measurement of natural organic matter (NOM) molar mass (MM)...
October 27, 2016: Journal of Chromatography. A
Wei Z Wang
: Both adipose-derived stem cells (ASCs) and stromal vascular fraction (SVF) have been demonstrated to have regenerative properties with therapeutic potential for numerous diseases through local or topical applications. However, it is unclear whether ASC or SVF can be delivered systemically through an intra-arterial infusion. The purpose of this study was to examine the microcirculatory response in vivo on local intraarterial infusion of autogenic ASCs or SVF in a vascular pedicle isolated rat cremaster microcirculation model...
September 2016: Plastic and Reconstructive Surgery. Global Open
Catia Contado, Roberto Argazzi, Vincenzo Amendola
Many advanced industrial and biomedical applications that use silver nanoparticles (AgNPs), require that particles are not only nano-sized, but also well dispersed, not aggregated and not agglomerated. This study presents two methods able to give rapidly sizes of monodispersed AgNPs suspensions in the dimensional range of 20-100nm. The first method, based on the application of Mie's theory, determines the particle sizes from the values of the surface plasmon resonance wavelength (SPRMAX), read from the optical absorption spectra, recorded between 190nm and 800nm...
October 13, 2016: Journal of Chromatography. A
Stephan Holzschuh, Kathrin KaeƟ, Guilherme Volpe Bossa, Christiane Decker, Alfred Fahr, Sylvio May
Liposomal delivery constitutes a promising approach for i.v. administration of mTHPC because lipid membranes can host these drug molecules. This study investigates the transfer and release of temoporfin (mTHPC) to plasma proteins and stability of various liposomal formulations. To this end, we employed traces of radioactive markers and studied the effects of fatty acid chain length and the degree of saturation in the lipophilic tail, addition of cholesterol, and PEGylation of the membrane surface and different drug-to-lipid ratios...
October 18, 2016: Journal of Liposome Research
Alexander K Andrianov, Alexander Marin, Thomas R Fuerst
Two macromolecular immunoadjuvants - poly[di(carboxylatophenoxy)phosphazene], PCPP and poly[di(carboxylatoethylphenoxy)phosphazene], PCEP have been investigated for their molecular interactions with model and bio-pharmaceutically important proteins in solutions, as well as for their TLR stimulatory effects and pH-dependent membrane disruptive activity in cellular assays. Solution interactions between polyphosphazenes and proteins, including antigens and soluble immune receptor proteins, have been studied using Asymmetric Flow Field Flow Fractionation (AF4) and Dynamic Light Scattering (DLS) at near physiological conditions - phosphate buffered saline, pH 7...
October 17, 2016: Biomacromolecules
Xiaojing Fu, Luis Cueto-Felgueroso, Ruben Juanes
We study the evolution of binary mixtures far from equilibrium, and show that the interplay between phase separation and hydrodynamic instability can arrest the Ostwald ripening process characteristic of nonflowing mixtures. We describe a model binary system in a Hele-Shaw cell using a phase-field approach with explicit dependence of both phase fraction and mass concentration. When the viscosity contrast between phases is large (as is the case for gas and liquid phases), an imposed background flow leads to viscous fingering, phase branching, and pinch off...
September 2016: Physical Review. E
Wei Li, Yingpeng Guo, Aixiang Zhang, Huaigu Chen
Sharp eyespot on wheat is caused by Rhizoctonia cerealis anastomosis group D subgroup I (AG-DI) and is an economically important stem-base disease of wheat in temperate regions worldwide. However, the understanding about the field population structure of R. cerealis is limited. In this study, the genetic structure of four wheat-infecting populations in China was investigated using six microsatellite markers characterized from the transcriptome data of R. cerealis AG-DI. A total of 173 unique genotypes were identified among 235 fungal isolates...
October 11, 2016: Phytopathology
Dalila Vescovi, Stefan Luding
Simple homogeneous shear flows of frictionless, deformable particles are studied by particle simulations at large shear rates and for differently soft, deformable particles. Particle stiffness sets a time-scale that can be used to scale the physical quantities; thus the dimensionless shear rate, i.e. the inertial number I (inversely proportional to pressure), can alternatively be expressed as inversely proportional to the square root of particle stiffness. Asymptotic scaling relations for the field variables pressure, shear stress and granular temperature are inferred from simulations in both fluid and solid regimes, corresponding to unjammed and jammed conditions...
September 26, 2016: Soft Matter
Monica Mattarozzi, Michele Suman, Claudia Cascio, Davide Calestani, Stefan Weigel, Anna Undas, Ruud Peters
Estimating consumer exposure to nanomaterials (NMs) in food products and predicting their toxicological properties are necessary steps in the assessment of the risks of this technology. To this end, analytical methods have to be available to detect, characterize and quantify NMs in food and materials related to food, e.g. food packaging and biological samples following metabolization of food. The challenge for the analytical sciences is that the characterization of NMs requires chemical as well as physical information...
October 3, 2016: Analytical and Bioanalytical Chemistry
Katri Eskelin, Mirka Lampi, Florian Meier, Evelin Moldenhauer, Dennis H Bamford, Hanna M Oksanen
Detailed biochemical and biophysical characterization of viruses requires viral preparations of high quantity and purity. The optimization of virus production and purification is an essential, but laborious and time-consuming process. Asymmetric flow field flow fractionation (AF4) is an attractive alternative method for virus purification because it is a rapid and gentle separation method that should preserve viral infectivity. Here we optimized the AF4 conditions to be used for purification of a model virus, bacteriophage PRD1, from various types of starting materials...
October 21, 2016: Journal of Chromatography. A
Kelvin J Richards
Viruses are known to impact blooms of phytoplankton in the ocean, in some cases causing the bloom to crash. Here, using a population model that includes viral infection, we investigate the conditions under which the presence of a virus significantly impacts the population dynamics. A major focus is how spatial variability influences the spread of an epidemic in a stirring and mixing field. The combination of viral infection and diffusion can cause waves of the epidemic to sweep through the domain, with the epidemic lasting much longer than in the homogeneous case...
September 27, 2016: Journal of Theoretical Biology
Richard d'Arcy, Arianna Gennari, Roberto Donno, Nicola Tirelli
Families of amphiphilic oxidation-responsive polymers (poly(ethylene glycol)-polysulfides) with different architectures (linear, 4, 6, and 8-armed stars and 10, 15, and 20-armed combs) and compositions (variable ethylene sulfide/propylene sulfide ratio) are prepared. In water, all the polymers assemble in spherical micelles, with critical micellar concentrations <0.01 mg mL(-1) for all the branched polymers. Triple-detection gel permeation chromatography (GPC) and asymmetric field flow fractionation (AFFF) with dynamic and static light scattering detection, respectively, show an increasing compaction of the polymeric coil and a strong reduction of the aggregation number with increasing degree of branching...
December 2016: Macromolecular Rapid Communications
Aljosha-Rakim Jochem, Genesis Ngwa Ankah, Lars-Arne Meyer, Stephan Elsenberg, Christoph Johann, Tobias Kraus
Flow field-flow fractionation is a powerful method for the analysis of nanoparticle size distributions, but its widespread use has been hampered by large analyte losses, especially of metal nanoparticles. Here, we report on the colloidal mechanisms underlying the losses. We systematically studied gold nanoparticles (AuNPs) during asymmetrical flow field-flow fractionation (AF4) by systematic variation of the particle properties and the eluent composition. Recoveries of AuNPs (core diameter 12 nm) stabilized by citrate or polyethylene glycol (PEG) at different ionic strengths were determined...
October 7, 2016: Analytical Chemistry
Raluca G Chelu, Kevin W Wanambiro, Albert Hsiao, Laurens E Swart, Teun Voogd, Allard T van den Hoven, Matthijs van Kranenburg, Adriaan Coenen, Sara Boccalini, Piotr A Wielopolski, Mika W Vogel, Gabriel P Krestin, Shreyas S Vasanawala, Ricardo P J Budde, Jolien W Roos-Hesselink, Koen Nieman
OBJECTIVES: In this study, we evaluated a cloud-based platform for cardiac magnetic resonance (CMR) four-dimensional (4D) flow imaging, with fully integrated correction for eddy currents, Maxwell phase effects, and gradient field non-linearity, to quantify forward flow, regurgitation, and peak systolic velocity over the pulmonary artery. METHODS: We prospectively recruited 52 adult patients during one-year period from July 2014. The 4D flow and planar (2D) phase-contrast (PC) were acquired during same scanning session, but 4D flow was scanned after injection of a gadolinium-based contrast agent...
October 2016: European Journal of Radiology
J Omar, A Boix, G Kerckhove, C von Holst
Titanium dioxide (TiO2) has various applications in consumer products and is also used as an additive in food and feeding stuffs. For the characterisation of this product, including the determination of nanoparticles, there is a strong need for the availability of corresponding methods of analysis. This paper presents an optimisation process for the characterisation of polydisperse-coated TiO2 nanoparticles. As a first step, probe ultrasonication was optimised using a central composite design in which the amplitude and time were the selected variables to disperse, i...
December 2016: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
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