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field flow fractionation

Xiao-Ping Yi, Ya-Li Zhang, He-Sheng Yao, Ji-Mei Han, Wah Soon Chow, Da-Yong Fan, Wang-Feng Zhang
To clarify the influence of water deficit on the functionality of the photosynthetic apparatus of cotton plants, leaf gas exchange, chlorophyll a fluorescence, and P700 redox state were examined in field-grown cotton Gossypium hirsutum L. cv. Xinluzao 45. In addition, we measured changes in the P515 signal and analyzed the activity of ATP synthase and the trans-thylakoid proton gradient (ΔpH). With increasing water deficit, the net CO2 assimilation rate (AN) and stomatal conductance (gs) significantly decreased, but the maximum quantum efficiency of PSII photochemistry (Fv/Fm) did not change...
November 10, 2017: Journal of Plant Physiology
Pravesh Kumar Bundhun, Chakshu Gupta, Feng Huang
BACKGROUND: Nowadays, fraction flow reserve (FFR) is being discussed in every percutaneous coronary intervention (PCI) capable hospitals. Owing to recent development in the medical field, FFR-guided PCI should be able to find a place in Interventional Cardiology. At present, the importance of FFR to stratify patients who require PCI has seldom systematically been investigated. In this analysis, we aimed to compare the major adverse cardiac events (MACEs) mainly in patients with stable coronary artery disease (CAD) to whom PCI was recommended and deferred respectively based on the FFR value...
November 2017: Medicine (Baltimore)
Kyunil Rah, Sujeong Han, Jaeyeong Choi, Chul Hun Eum, Seungho Lee
We investigate an explicit role of the ionic strength in the retention behaviors of polystyrene (PS) latex particles in sedimentation field-flow fractionation (SdFFF) by hinging upon the retention theory recently developed [1] asR=(Ro+vb(*))/(1+vb(*)). Here R is an experimental retention ratio, and Ro is the analytical expression of the standard retention theory based on the parabolic flow velocity. The reduced boundary velocityvb(*) is expressed in terms of the ionic strength I of the carrier liquid as vb(*)=vb,o(*)/(1+εI), where vb,o(*)=0...
November 7, 2017: Journal of Chromatography. A
Mengxi Wu, Zhangming Mao, Kejie Chen, Hunter Bachman, Yuchao Chen, Joseph Rufo, Liqiang Ren, Peng Li, Lin Wang, Tony Jun Huang
The separation of nanoscale particles based on their differences in size is an essential technique to the nanoscience and nanotechnology community. Here, nanoparticles are successfully separated in a continuous flow by using tilted-angle standing surface acoustic waves. The acoustic field deflects nanoparticles based on volume, and the fractionation of nanoparticles is optimized by tuning the cutoff parameters. The continuous separation of nanoparticlesis demonstrated with a ≈90% recovery rate. The acoustic nanoparticle separation method is versatile, non-invasive, and simple...
April 11, 2017: Advanced Functional Materials
Colm A Ryan, Blake R Johnson, Diego Ristè, Brian Donovan, Thomas A Ohki
We describe the hardware, gateware, and software developed at Raytheon BBN Technologies for dynamic quantum information processing experiments on superconducting qubits. In dynamic experiments, real-time qubit state information is fed back or fed forward within a fraction of the qubits' coherence time to dynamically change the implemented sequence. The hardware presented here covers both control and readout of superconducting qubits. For readout, we created a custom signal processing gateware and software stack on commercial hardware to convert pulses in a heterodyne receiver into qubit state assignments with minimal latency, alongside data taking capability...
October 2017: Review of Scientific Instruments
Pedro Novo, Margherita Dell'Aica, Matthias Jender, Stefan Höving, René P Zahedi, Dirk Janasek
A general difficulty in the miniaturization of free-flow electrophoresis relates to the need to separate electrodes and separation bed compartments. This is usually performed by using membranes, which are either difficult to fabricate and integrate into microfluidic channels, or not stable over time. Here, we propose the use of track-etched polycarbonate membranes. Fabrication of the miniaturized device and integration of the membrane was simple, reproducible and allows for long shelf times. Furthermore, the membranes were resistant to high pressure values (up to 10(5) Pa), and contributed negligible electrical resistance, allowing setting of electric fields at the separation bed with high efficiency...
October 30, 2017: Analyst
Ali Imanparast, Nasser Fatouraee, Farhad Sharif
BACKGROUND: Understanding the effects of cardiac diseases on the heart's functionality which is the purpose of many biomedical researches, directly affects the diagnostic and therapeutic methods. Myocardial infarction (MI) is a common complication of cardiac ischemia, however, the impact of MI on the left ventricle (LV) flow patterns has not been widely considered by computational fluid dynamics studies thus far. METHODS: In this study, we present an insightful numerical method that creates an artificial MI on an image-based fluid-structure interactional model of normal LV to investigate its influence on the flow in comparison with the normal case...
October 26, 2017: Mathematical Biosciences
X Y Xu, S J Ni, M Fu, X Zheng, N Luo, W G Weng
Inhalation injury from exposure to fire smoke is one of the causes of burn-related death. In this study, a realistic three-dimensional human upper airway model was built from magnetic resonance imaging (MRI) scanned images, including the nasal, oral, pharynx, larynx, trachea and part of the first generation of the tracheobronchial tree, as well as a tissue region from the pharynx to the upper bronchi. The Transition Shear Stress Transport (SST-transition) turbulence model, Pennes bioheat transfer equation, convective boundary conditions and a Lagrangian frame were applied and verified with experimental measurements to simulate the airflow fields, temperature distributions and particle deposition in the human airway model...
December 2017: Journal of Thermal Biology
Sakir Akin, Dinis Dos Reis Miranda, Kadir Caliskan, Osama I Soliman, Goksel Guven, Ard Struijs, Robert J van Thiel, Lucia S Jewbali, Alexandre Lima, Diederik Gommers, Felix Zijlstra, Can Ince
BACKGROUND: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly adopted for the treatment of cardiogenic shock (CS). However, a marker of successful weaning remains largely unknown. Our hypothesis was that successful weaning is associated with sustained microcirculatory function during ECMO flow reduction. Therefore, we sought to test the usefulness of microcirculatory imaging in the same sublingual spot, using incident dark field (IDF) imaging in assessing successful weaning from VA-ECMO and compare IDF imaging with echocardiographic parameters...
October 26, 2017: Critical Care: the Official Journal of the Critical Care Forum
Gustavo Moreno-Martin, Micaela Pescuma, Teresa Pérez-Corona, Fernanda Mozzi, Yolanda Madrid
Selenium nanoparticles (SeNPs) were synthesized by a green technology using lactic acid bacteria (LAB, Lactobacillus acidophilus, L. delbrueckii subsp. bulgaricus and L. reuteri). The exposure of aqueous sodium selenite to LAB led to the synthesis of SeNPs. Characterization of SeNPs by transmission electron microscopy with energy dispersive X-ray spectrum (EDXS) analysis revealed the presence of stable, predominantly monodispersed and spherical SeNPs of an average size of 146 ± 71 nm. Additionally, SeNPs hydrodynamic size was determined by dispersive light scattering (DLS) and nanoparticle tracking analysis (NTA)...
November 1, 2017: Analytica Chimica Acta
Steven Kinio, James K Mills
This paper presents the design and experimental performance of a microelectrode-based device to selectively lyse cells in a flow in a microfluidic channel. Localized cell lysis is achieved by utilizing "irreversible electroporation", in which cells are exposed to high magnitude electric pulses. Localized cell lysis in a flow has research applications and may allow for removal of harmful cells such as circulating tumor cells from blood. Due to the dependence of this technique on the magnitude of the applied electric field, lethal electric field regions can be localized in the channel by calibration of the applied voltage...
October 17, 2017: IEEE Transactions on Nanobioscience
Lindsey A Crowe, Gibran Manasseh, Aneta Chmielewski, Anne-Lise Hachulla, Daniel Speicher, Andreas Greiser, Hajo Muller, Thomas De Perrot, Jean-Paul Vallee, Rares Salomir
OBJECTIVES: We demonstrate the use of a Magnetic-Resonance (MR)-compatible ultrasound (US) imaging probe using spatially-resolved Doppler for diagnostic quality cardiovascular MR imaging as an initial step towards hybrid US/MR fetal imaging. METHODS: A newly developed technology for a dedicated MR-compatible phased array ultrasound-imaging probe acquired pulsed color Doppler carotid images, which were converted in near-real time to a trigger signal for cardiac cine and flow quantification MRI...
October 17, 2017: IEEE Transactions on Bio-medical Engineering
Qihui Liang, Di Wu, Bailing Qiu, Nanyin Han
Field-flow fractionation (FFF) is a kind of mature separation technologies in the field of bioanalysis, feasible of separating analytes with the differences of certain physical and chemical properties by the combination effects of two orthogonal force fields (flow field and external force field). Asymmetrical flow field-flow fractionation (AF4) is a vital subvariant of FFF, which applying a vertical flow field as the second dimension force field. The separation in AF4 opening channel is carried out by any composition carrier fluid, universally and effectively used in separation of bioparticles and biopolymers due to the non-invasivity feature...
September 8, 2017: Se Pu, Chinese Journal of Chromatography
Wenhui Zhang, Chunxue Cai, Jing Wang, Zhen Mao, Yueqiu Li, Liang Ding, Shigang Shen, Haiyang Dou
Home-made asymmetrical flow field-flow fractionation (AF4) system, online coupled with ultraviolet/visible (UV/Vis) detector was employed for the separation and size characterization of low density lipoprotein (LDL) in egg yolk plasma. At close to natural condition of egg yolk, the effects of cross flow rate, sample loading, and type of membrane on the size distribution of LDL were investigated. Under the optimal operation conditions, AF4-UV/Vis provides the size distribution of LDL. Moreover, the precision of AF4-UV/Vis method proposed in this work for the analysis of LDL in egg yolk plasma was evaluated...
August 8, 2017: Se Pu, Chinese Journal of Chromatography
Zhi-Qiang Tan, Yong-Guang Yin, Xiao-Ru Guo, Meseret Amde, Myeong Hee Moon, Jing-Fu Liu, Gui-Bin Jiang
It is a great challenge to monitor the physical and chemical transformation of nanoparticles at environmentally relevant concentration levels, mainly because the commonly used techniques like dynamic light scattering and transmission electron microscopy are unable to characterize and quantify trace level nanoparticles in complex matrices. Herein, we demonstrate the on-line coupled system of hollow fiber flow field-flow fractionation (HF5), minicolumn concentration, and inductively coupled plasma mass spectrometry (ICPMS) detection as an efficient approach to study the aggregation and chemical transformation of silver nanoparticles (AgNPs) and ionic Ag species in the aqueous environment at ng/mL levels...
November 7, 2017: Environmental Science & Technology
Katri Eskelin, Mirka Lampi, Florian Meier, Evelin Moldenhauer, Dennis H Bamford, Hanna M Oksanen
Viruses come in various shapes and sizes, and a number of viruses originate from extremities, e.g. high salinity or elevated temperature. One challenge for studying extreme viruses is to find efficient purification conditions where viruses maintain their infectivity. Asymmetrical flow field-flow fractionation (AF4) is a gentle native chromatography-like technique for size-based separation. It does not have solid stationary phase and the mobile phase composition is readily adjustable according to the sample needs...
November 2017: Extremophiles: Life Under Extreme Conditions
Roberto Donno, Arianna Gennari, Enrique Lallana, Julio M Rios De La Rosa, Richard d'Arcy, Kevin Treacher, Kathryn Hill, Marianne Ashford, Nicola Tirelli
We have employed microfluidics (cross-shaped chip) for the preparation of drug-loaded poly(lactic acid-co-glycolic acid) (PLGA) nanoparticles. The polymer precipitates from an acetone solution upon its controlled laminar mixing (flow focusing) with an aqueous solution of a surfactant, allowing for an operator-independent, up-scalable and reproducible preparative process of nanoformulations. Firstly, using PEGylated surfactants we have compared batch and microfluidic processes, and showed the superior reproducibility of the latter and its strong dependency on the acetone/water ratio (flow rate ratio)...
October 7, 2017: International Journal of Pharmaceutics
Huacheng Xu, Erin M Houghton, Christopher J Houghton, Laodong Guo
Dynamic variations in chemical composition and size distribution of dissolved organic matter (DOM) along the river-lake interface in the Fox River plume were investigated using ultrafiltration, flow field-flow fractionation, UV-Vis and fluorescence spectroscopy and parallel factor analysis. On average, ~67% of bulk dissolved organic carbon (DOC) were partitioned in the <1kDa (actual cutoff 2.5kDa) low molecular weight fraction, and the other 33% were in the 1kDa-0.7μm colloidal phase. Concentrations of DOC and chromophoric DOM in the bulk and size-fractionated samples decreased monotonously with decreasing conductivity from river to bay waters, demonstrating a dominant terrestrial source and quasi conservative mixing behavior...
February 15, 2018: Science of the Total Environment
Vladimir A Andryushchenko, Sergei F Chekmarev
Owing to its small size and very fast folding rate, the Trp-cage miniprotein has become a benchmark system to study protein folding. Two folding pathways were found to be characteristic of this protein: pathway I, in which the hydrophobic collapse precedes the formation of α-helix, and pathway II, in which the events occur in the reverse order. At the same time, the relative contribution of these pathways at different temperatures as well as the nature of transition from one pathway to the other remain unclear...
October 5, 2017: Journal of Biological Physics
Simona Sitar, Valerija Vezočnik, Peter Maček, Ksenija Kogej, David Pahovnik, Ema Žagar
An asymmetrical flow field-flow fractionation (AF4) technique coupled to a multiangle light scattering (MALS) detector with an embedded dynamic light scattering (DLS) module was introduced to study the size characteristics and shape of soft particles of various size and type: polystyrene nanosphere size standards, lipid droplets (LDs), and large unilamellar vesicles (LUVs). A range of flow velocities through the LS detector, at which accurate hydrodynamic size can be extracted from the DLS in flow mode, was studied since the particles subjected to a longitudinal flow exhibit not only the Brownian motion due to diffusion but also the translational movement...
November 7, 2017: Analytical Chemistry
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